How Does Poly(hydroxyalkanoate) Affect Methane Production from the Anaerobic Digestion of Waste-Activated Sludge?

PubMed

Wang, Dongbo; Zhao, Jianwei; Zeng, Guangming; Chen, Yinguang; Bond, Philip L; Li, Xiaoming

2015-10-20

Recent studies demonstrate that, besides being used for production of biodegradable plastics, poly(hydroxyalkanoate) (PHA) that is accumulated in heterotrophic microorganisms during wastewater treatment has another novel application direction, i.e., being utilized for enhancing methane yield during the anaerobic digestion of waste-activated sludge (WAS). To date, however, the underlying mechanism of how PHA affects methane production remains largely unknown, and this limits optimization and application of the strategy. This study therefore aims to fill this knowledge gap. Experimental results showed that with the increase of sludge PHA levels from 21 to 184 mg/g of volatile suspended solids (VSS) the methane yield linearly increased from 168.0 to 246.1 mL/g of VSS (R(2) = 0.9834). Compared with protein and carbohydrate (the main components of a cell), PHA exhibited a higher biochemical methane potential on a unit VSS basis. It was also found that the increased PHA not only enhanced cell disruption of PHA cells but also benefited the soluble protein conversion of both PHA- and non-PHA cells. Moreover, the reactor fed with higher PHA sludge showed greater sludge hydrolysis and acidification than those fed with the lower PHA sludges. Further investigations using fluorescence in situ hybridization and enzyme analysis revealed that the increased PHA enhanced the abundance of methanogenic Archaea and increased the activities of protease, acetate kinase, and coenzyme F420, which were consistent with the observed methane yield. This work provides insights into PHA-involved WAS digestion systems and may have important implications for future operation of wastewater treatment plants.

Ultrasound pretreatment for enhanced biogas production from olive mill wastewater.

PubMed

Oz, Nilgun Ayman; Uzun, Alev Cagla

2015-01-01

This study investigates applicability of low frequency ultrasound technology to olive mill wastewaters (OMWs) as a pretreatment step prior to anaerobic batch reactors to improve biogas production and methane yield. OMWs originating from three phase processes are characterized with high organic content and complex nature. The treatment of the wastewater is problematic and alternative treatment options should be investigated. In the first part of the study, OMW samples were subjected to ultrasound at a frequency of 20kHz with applied powers varying between 50 and 100W under temperature controlled conditions for different time periods in order to determine the most effective sonication conditions. The level of organic matter solubilization at ultrasound experiments was assessed by calculating the ratio of soluble chemical oxygen demand/total chemical oxygen demand (SCOD/TCOD). The results revealed that the optimum ultrasonic condition for diluted OMW is 20kHz, 0.4W/mL for 10min. The application of ultrasound to OMW increased SCOD/TCOD ratio from 0.59 to 0.79. Statistical analysis (Friedman's tests) show that ultrasound was significantly effective on diluted OMW (p<0.05) in terms of SCOD parameter, but not for raw OMW (p>0.05). For raw OMW, this increase has been found to be limited due to high concentration of suspended solids (SS). In the second part of the study, biogas and methane production rates of anaerobic batch reactor fed with the ultrasound pretreated OMW samples were compared with the results of control reactor fed with untreated OMW in order to determine the effect of sonication. A nonparametric statistical procedure, Mann-Whitney U test, was used to compare biogas and methane production from anaerobic batch reactors for control and ultrasound pretreated samples. Results showed that application of low frequency ultrasound to OMW significantly improved both biogas and methane production in anaerobic batch reactor fed with the wastewater (p<0.05). Anaerobic batch reactor fed with ultrasound pretreated diluted OMW produced approximately 20% more biogas and methane compared with the untreated one (control reactor). The overall results indicated that low frequency ultrasound pretreatment increased soluble COD in OMW and subsequently biogas production. Copyright © 2014 Elsevier B.V. All rights reserved.

Changes in methane emission, rumen fermentation, and methanogenic community in response to silage and dry cornstalk diets.

PubMed

Chong, Liu; Zhuping, Zhu; Tongjun, Guo; Yongming, Luo; Hongmin, Dong

2014-06-01

This study aimed to investigate the effect of silage or dry cornstalk diets on methane emission, rumen fermentation, and methanogenic community, and reveal whether the change of methanogenic compositions was related to the methane production. A total of 39 sheep were divided into four groups, fed diets of different concentrate level based on silage or dry cornstalk roughage for 40 days. It was found that, at 20% concentrate level, the sheep fed silage could suppress methanogenesis significantly in contrast with the silage diet (p < 0.05). The ruminal acetate:propionate ratio was 3.17 in the silage-fed sheep significantly lower than 3.78 in the dry cornstalk-fed sheep (p < 0.05), reflecting the effect of fermentation on methane output was related to roughage types. Furthermore, the methanogens was found to be significantly lower abundance (p < 0.05), and showed a different pattern using multivariate statistical analysis in silage-fed sheep. Compared with dry cornstalk diet, silage diet of 20% concentrate reduced methane production, decreased methanogenic abundance, and induced change of Methanobrevibacter composition at strain levels. This study showed variation of methanogenic compositions at strain level and its probable relationship with methane production, and provided microbial information to explain the low methane output when the animals were fed silage. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Food Waste Co-Digestion on Digestion, Dewatering, and Cake Quality.

PubMed

Higgins, Matthew; Rajagopalan, Ganesh; Miller, Andre; Brown, Jeffrey; Beightol, Steven

2017-01-01

  The objective of this study was to evaluate the effect of food waste addition on anaerobic digestion performance as well as downstream parameters including dewatering, cake quality, and filtrate quality. Laboratory-scale digesters were fed processed food waste at rates of 25%, 45%, and 65% increased chemical oxygen demand (COD) loading rates compared to a control fed only primary and secondary solids. The specific methane yield increased from 370 L CH4/kg VSadded for the control to 410, 440, and 470 L CH4/kg VSadded for the 25, 45, and 65% food waste addition, respectively. The cake solids after dewatering were all higher for the food waste digesters compared to the control, with the highest cake solids being measured for the 45% food-waste loading. Compared to the control digester, the biosolids odorant concentration increased for the lowest dose of food waste. Odorant concentrations were below detection for the highest food waste loading.

Fed-batch anaerobic valorization of slaughterhouse by-products with mesophilic microbial consortia without methane production.

PubMed

Pessiot, J; Nouaille, R; Jobard, M; Singhania, R R; Bournilhas, A; Christophe, G; Fontanille, P; Peyret, P; Fonty, G; Larroche, C

2012-07-01

This work aimed at setting up a fully instrumented, laboratory-scale bioreactor enabling anaerobic valorization of solid substrates through hydrogen and/or volatile fatty acid (VFA) production using mixed microbial populations (consortia). The substrate used was made of meat-based wastes, especially from slaughterhouses, which are becoming available in large amounts as a consequence of the growing constraints for waste disposal from meat industry. A reconstituted microbial mesophilic consortium without Archaebacteria (methanogens), named PBr, was cultivated in a 5-L anaerobic bioreactor on slaughterhouse wastes. The experiments were carried out with sequential fed-batch operations, including liquid medium removal from the bioreactor and addition of fresh substrate. VFAs and nitrogen were the main metabolites observed, while hydrogen accumulation was very low and no methane production was evidenced. After 1,300 h of culture, yields obtained for VFAs reached 0.38 g/g dry matter. Strain composition of the microbial consortium was also characterized using molecular tools (temporal temperature gradient gel electrophoresis and gene sequencing).

Performance of a novel two-phase continuously fed leach bed reactor for demand-based biogas production from maize silage.

PubMed

Linke, Bernd; Rodríguez-Abalde, Ángela; Jost, Carsten; Krieg, Andreas

2015-02-01

This study investigated the potential of producing biogas on demand from maize silage using a novel two-phase continuously fed leach bed reactor (LBR) which is connected to an anaerobic filter (AF). Six different feeding patterns, each for 1week, were studied at a weekly average of a volatile solids (VS) loading rate of 4.5 g L(-1) d(-1) and a temperature of 38°C. Methane production from the LBR and AF responded directly proportional to the VS load from the different daily feeding and resulted in an increase up to 50-60% per day, compared to constant feeding each day. The feeding patterns had no impact on VS methane yield which corresponded on average to 330 L kg(-1). In spite of some daily shock loadings, carried out during the different feeding patterns study, the reactor performance was not affected. A robust and reliable biogas production from stalky biomass was demonstrated. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lambs Fed Fresh Winter Forage Rape (Brassica napus L.) Emit Less Methane than Those Fed Perennial Ryegrass (Lolium perenne L.), and Possible Mechanisms behind the Difference

PubMed Central

Sun, Xuezhao; Henderson, Gemma; Cox, Faith; Molano, German; Harrison, Scott J.; Luo, Dongwen; Janssen, Peter H.; Pacheco, David

2015-01-01

The objectives of this study were to examine long-term effects of feeding forage rape (Brassica napus L.) on methane yields (g methane per kg of feed dry matter intake), and to propose mechanisms that may be responsible for lower emissions from lambs fed forage rape compared to perennial ryegrass (Lolium perenne L.). The lambs were fed fresh winter forage rape or ryegrass as their sole diet for 15 weeks. Methane yields were measured using open circuit respiration chambers, and were 22-30% smaller from forage rape than from ryegrass (averages of 13.6 g versus 19.5 g after 7 weeks, and 17.8 g versus 22.9 g after 15 weeks). The difference therefore persisted consistently for at least 3 months. The smaller methane yields from forage rape were not related to nitrate or sulfate in the feed, which might act as alternative electron acceptors, or to the levels of the potential inhibitors glucosinolates and S-methyl L-cysteine sulfoxide. Ruminal microbial communities in forage rape-fed lambs were different from those in ryegrass-fed lambs, with greater proportions of potentially propionate-forming bacteria, and were consistent with less hydrogen and hence less methane being produced during fermentation. The molar proportions of ruminal acetate were smaller and those of propionate were greater in forage rape-fed lambs, consistent with the larger propionate-forming populations and less hydrogen production. Forage rape contained more readily fermentable carbohydrates and less structural carbohydrates than ryegrass, and was more rapidly degraded in the rumen, which might favour this fermentation profile. The ruminal pH was lower in forage rape-fed lambs, which might inhibit methanogenic activity, shifting the rumen fermentation to more propionate and less hydrogen and methane. The significance of these two mechanisms remains to be investigated. The results suggest that forage rape is a potential methane mitigation tool in pastoral-based sheep production systems. PMID:25803688

Importance of storage time in mesophilic anaerobic digestion of food waste.

PubMed

Lü, Fan; Xu, Xian; Shao, Liming; He, Pinjing

2016-07-01

Storage was used as a pretreatment to enhance the methanization performance of mesophilic anaerobic digestion of food waste. Food wastes were separately stored for 0, 1, 2, 3, 4, 5, 7, and 12days, and then fed into a methanogenic reactor for a biochemical methane potential (BMP) test lasting up to 60days. Relative to the methane production of food waste stored for 0-1day (285-308mL/g-added volatile solids (VSadded)), that after 2-4days and after 5-12days of storage increased to 418-530 and 618-696mL/g-VSadded, respectively. The efficiency of hydrolysis and acidification of pre-stored food waste in the methanization reactors increased with storage time. The characteristics of stored waste suggest that methane production was not correlated with the total hydrolysis efficiency of organics in pre-stored food waste but was positively correlated with the storage time and acidification level of the waste. From the results, we recommend 5-7days of storage of food waste in anaerobic digestion treatment plants. Copyright © 2016. Published by Elsevier B.V.

New insights into the enhanced performance of high solid anaerobic digestion with dewatered sludge by thermal hydrolysis: Organic matter degradation and methanogenic pathways.

PubMed

Chen, Sisi; Li, Ning; Dong, Bin; Zhao, Wentao; Dai, Lingling; Dai, Xiaohu

2018-01-15

Two lab-scale high solid anaerobic digesters fed with untreated sludge (R1) and thermally hydrolyzed sludge (R2) were operated to investigate the influence of thermal hydrolysis pretreatment (THP) on the degradation of individual macromolecular organic components (MOCs), as well as the functional and metabolic responses of microbes during anaerobic digestion (AD). The degradation of MOCs was improved by THP at different rates, in which improved degradation of proteins (by 49.0%) and hemicelluloses (by 25.0%) were the main factors contributing to the increase in volatile solids (VS) reduction. However, no enhancement of final degradation extent of MOCs was observed. With a more densified microbial population, R2 was also enriched in genes involved in amino acid and carbohydrate metabolism, reflected in the enhanced degradation of proteins and carbohydrates. After THP, the methanogenic pathway shifted from strict acetoclastic methanogenesis to acetoclastic/hydrogenotrophic methanogenesis, consistent with the enhanced methane production and the increase of methane content. Copyright © 2017 Elsevier B.V. All rights reserved.

Samaria-doped Ceria Modified Ni/YSZ Anode for Direct Methane Fuel in Tubular Solid Oxide Fuel Cells by Impregnation Method

NASA Astrophysics Data System (ADS)

Zhang, Long-shan; Gao, Jian-feng; Tian, Rui-fen; Xia, Chang-rong

2009-08-01

A porous NiO/yttria-stabilized zirconia anode substrate for tubular solid oxide fuel cells was prepared by gel casting technique. Nano-scale samaria-doped ceria (SDC) particles were formed onto the anode substrate to modify the anode microstructure by the impregnation of solution of Sm(NO3)3 and Ce(NO3)3. Electrochemical impedance spectroscopy, current-voltage and current-powder curves of the cells were measured using an electrochemical workstation. Scanning electron microcopy was used to observe the microstructure. The results indicate that the stability of the performance of the cell operated on humidified methane can be significantly improved by incorporating the nano-structured SDC particles, compared with the unmodified cell. This verifies that the coated SDC electrodes are very effective in suppressing catalytic carbon formation by blocking methane from approaching the Ni, which is catalytically active towards methane pyrolysis. In addition, it was found that a small amount of deposited carbon is beneficial to the performance of the anode. The cell showed a peak power density of 225 mW/cm2 when it was fed with H2 fuel at 700 °C, but the power density increased to 400 mW/cm2 when the fuel was switched from hydrogen to methane at the same flow rate. Methane conversion achieved about 90%, measured by gas chromatogram with a 10.0 mL/min flow rate of fuel at 700 °C. Although the carbon deposition was not suppressed absolutely, some deposited carbon was beneficial for performance improvement.

Effect of the addition of fatty by-products from the refining of vegetable oil on methane production in co-digestion.

PubMed

Torrijos, M; Sousbie, P; Badey, L; Bosque, F; Steyer, J P

2012-01-01

The purpose of this work was to investigate the effects of the addition of by-products from the refining of vegetable oil on the behavior of co-digestion reactors treating a mixture of grass, cow dung and fruit and vegetable waste. Three by-products were used: one soapstock, one used winterization earth and one skimming of aeroflotation of the effluents. Three 15 l reactors were run in parallel and fed five times a week. In a first phase of 4 weeks, the three reactors were fed with the co-digestion substrates alone (grass, cow dung and fruit and vegetable waste) at an organic loading rate (OLR) of 1.5 g VS/kg d (VS: volatile solids). Then, a different by-product from the refining of oil was added to the feed of each reactor at an OLR of 0.5 g VS/kg d, generating a 33% increase in the OLR. The results show that the addition of by-products from the refining of oil is an efficient way of increasing the methane production of co-digestion reactors thanks to high methane yield of such by-products (0.69-0.77 l CH(4)/g VS loaded). In fact, in this work, it was possible to raise the methane production of the reactors by about 60% through a 33% increase in the OLR thanks to the addition of the by-products from the refining of vegetable oil.

High solids co-digestion of food and landscape waste and the potential for ammonia toxicity.

PubMed

Drennan, Margaret F; DiStefano, Thomas D

2014-07-01

A pilot-scale study was completed to determine the feasibility of high-solids anaerobic digestion (HSAD) of a mixture of food and landscape wastes at a university in central Pennsylvania (USA). HSAD was stable at low loadings (2g COD/L-day), but developed inhibitory ammonia concentrations at high loadings (15 g COD/L-day). At low loadings, methane yields were 232 L CH4/kg COD fed and 229 L CH4/kg VS fed, and at high loadings yields were 211 L CH4/kg COD fed and 272 L CH4/kg VS fed. Based on characterization and biodegradability studies, food waste appears to be a good candidate for HSAD at low organic loading rates; however, the development of ammonia inhibition at high loading rates suggests that the C:N ratio is too low for use as a single substrate. The relatively low biodegradability of landscape waste as reported herein made it an unsuitable substrate to increase the C:N ratio. Codigestion of food waste with a substrate high in bioavailable carbon is recommended to increase the C:N ratio sufficiently to allow HSAD at loading rates of 15 g COD/L-day. Copyright © 2014 Elsevier Ltd. All rights reserved.

Anaerobic co-digestion of sugarcane press mud with vinasse on methane yield.

PubMed

López González, Lisbet Mailin; Pereda Reyes, Ileana; Romero Romero, Osvaldo

2017-10-01

The conversion efficiency of high solids waste digestion as sugarcane press mud (P) may be limited due to hydrolysis step. The option of co-digestion with vinasse, main liquid waste generated from ethanol production, was investigated under batch regime at mesophilic conditions (37.5±1°C) and the best mixture was evaluated under semicontinuous regime in stirred-tank reactors. The maximum values for methane yield in batch tests were for V 75 /P 25 and V 50 /P 50 mixtures (on basis of the chemical oxygen demand (COD) percentage added in the mixture), with an average value of 246NmL CH 4 g -1 COD fed , which was 13% higher than that of press mud alone. A highest methane production rate of 69.6NmL CH 4 g -1 COD fed -1 d -1 was obtained for the mixtureV 75 /P 25 . During the experiment carried out in CSTR reactors, the organic loading rate (OLR) was increased from 0.5 up to 2.2gVSL -1 d -1 . Methane yields of 365L CH 4 kg -1 VS and biogas productivities of 1.6LL -1 were obtained in co-digestion, which was 64% higher in comparison to mono-digestion. The performance of the process in mono-digestion was less stable than in co-digestion, with a significant fall of methane yield to 1.8kgVSm -3 d -1 , and a partial inhibition of the methanogenic archaeas when the OLR was increased up to 2.2kgVSm -3 d -1 . The co-digestion of vinasse with press mud is a good option for the treatment of streams at the alcohol-sugar industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bayr, S., E-mail: suvi.bayr@jyu.fi; Ojanperä, M.; Kaparaju, P.

Highlights: • Rendering wastes’ mono-digestion and co-digestion with potato pulp were studied. • CSTR process with OLR of 1.5 kg VS/m{sup 3} d, HRT of 50 d was unstable in mono-digestion. • Free NH{sub 3} inhibited mono-digestion of rendering wastes. • CSTR process with OLR of 1.5 kg VS/m{sup 3} d, HRT of 50 d was stable in co-digestion. • Co-digestion increased methane yield somewhat compared to mono-digestion. - Abstract: In this study, mono-digestion of rendering wastes and co-digestion of rendering wastes with potato pulp were studied for the first time in continuous stirred tank reactor (CSTR) experiments at 55more » °C. Rendering wastes have high protein and lipid contents and are considered good substrates for methane production. However, accumulation of digestion intermediate products viz., volatile fatty acids (VFAs), long chain fatty acids (LCFAs) and ammonia nitrogen (NH{sub 4}-N and/or free NH{sub 3}) can cause process imbalance during the digestion. Mono-digestion of rendering wastes at an organic loading rate (OLR) of 1.5 kg volatile solids (VS)/m{sup 3} d and hydraulic retention time (HRT) of 50 d was unstable and resulted in methane yields of 450 dm{sup 3}/kg VS{sub fed}. On the other hand, co-digestion of rendering wastes with potato pulp (60% wet weight, WW) at the same OLR and HRT improved the process stability and increased methane yields (500–680 dm{sup 3}/kg VS{sub fed}). Thus, it can be concluded that co-digestion of rendering wastes with potato pulp could improve the process stability and methane yields from these difficult to treat industrial waste materials.« less

Fate of LCFA in the co-digestion of cow manure, food waste and discontinuous addition of oil.

PubMed

Neves, L; Oliveira, R; Alves, M M

2009-12-01

Different concentrations of oily waste were added in a discontinuous mode and recurrently to anaerobic continuous stirred tank reactors fed with cow manure and food waste. Four continuous stirred tank reactors were run in parallel. A control reactor (R1) received no additional oil and R2, R3 and R4 received increasing concentrations of oil in two different experimental approaches. First, the lipids composition was forced to change suddenly, in three moments, without changing the total chemical oxygen demand (COD) fed to the reactors. The only long chain fatty acid (LCFA) detected onto the R1 solid matrix was palmitic acid (C16:0). Nevertheless in the solid matrix of R2, R3 and R4C16:0 and stearic acid were detected. For occasional increase in the oil concentration up to 7.7gCOD(oil)/L(reactor) (55% Oil(COD)/Total(COD)) no statistical differences were detected between the reactors, in terms of methane production, effluent soluble COD, effluent volatile fatty acids and total and volatile solids removal. Therefore this experiment allowed to conclude that cow manure-food waste co-digestion presents sufficient buffer capacity to endure solid-associated LCFA concentration up to 20-25gCOD-LCFA/kgTS. In a second experiment higher concentrations of oil were added, raising occasionally the concentration in the reactors to 9, 12, 15 and 18gCOD(oil)/L(reactor). All pulses had a positive effect in methane production, with the exception of the highest oil pulse concentration, that persistently impaired the reactor performance. This experiment demonstrates that threshold values for LCFA and C16:0 accumulation onto the solid matrix, of about 180-220gCOD-LCFA/kgTS and 120-150gCOD-C16:0/kgTS, should not be surpassed in order to prevent persistent reactor failure, as occurs in some full scale co-digestion plants.

Anaerobic co-digestion of food waste and dairy manure: effects of food waste particle size and organic loading rate.

PubMed

Agyeman, Fred O; Tao, Wendong

2014-01-15

This study was to comprehensively evaluate the effects of food waste particle size on co-digestion of food waste and dairy manure at organic loading rates increased stepwise from 0.67 to 3 g/L/d of volatile solids (VS). Three anaerobic digesters were fed semi-continuously with equal VS amounts of food waste and dairy manure. Food waste was ground to 2.5 mm (fine), 4 mm (medium), and 8 mm (coarse) for the three digesters, respectively. Methane production rate and specific methane yield were significantly higher in the digester with fine food waste. Digestate dewaterability was improved significantly by reducing food waste particle size. Specific methane yield was highest at the organic loading rate of 2g VS/L/d, being 0.63, 0.56, and 0.47 L CH4/g VS with fine, medium, and coarse food waste, respectively. Methane production rate was highest (1.40-1.53 L CH4/L/d) at the organic loading rate of 3 g VS/L/d. The energy used to grind food waste was minor compared with the heating value of the methane produced. Copyright © 2013 Elsevier Ltd. All rights reserved.

The effect of organic loading rate and retention time on hydrogen production from a methanogenic CSTR.

PubMed

Pakarinen, O; Kaparaju, P; Rintala, J

2011-10-01

The possibility of shifting a methanogenic process for hydrogen production by changing the process parameters viz., organic loading rate (OLR) and hydraulic retention time (HRT) was evaluated. At first, two parallel semi-continuously fed continuously stirred tank reactors (CSTR) were operated as methanogenic reactors (M1 and M2) for 78 days. Results showed that a methane yield of 198-218 L/kg volatile solids fed (VS(fed)) was obtained when fed with grass silage at an OLR of 2 kgVS/m³/d and HRT of 30 days. After 78 days of operation, hydrogen production was induced in M2 by increasing the OLR from 2 to 10 kgVS/m³/d and shortening the HRT from 30 to 6 days. The highest H₂ yield of 42 L/kgVS(fed) was obtained with a maximum H₂ content of 24%. The present results thus demonstrate that methanogenic process can be shifted towards hydrogen production by increasing the OLR and decreasing HRT. Copyright © 2011 Elsevier Ltd. All rights reserved.

Semi-continuous anaerobic digestion of solid poultry slaughterhouse waste: effect of hydraulic retention time and loading.

PubMed

Salminen, Esa A; Rintala, Jukka A

2002-07-01

We studied the effect of hydraulic retention time (HRT) and loading on anaerobic digestion of poultry slaughterhouse wastes, using semi-continuously fed, laboratory-scale digesters at 31 degrees C. The effect on process performance was highly significant: Anaerobic digestion appeared feasible with a loading of up to 0.8 kg volatile solids (VS)/m3 d and an HRT of 50-100 days. The specific methane yield was high, from 0.52 to 0.55 m3/kg VS(added). On the other hand, at a higher loading, in the range from 1.0 to 2.1 kg VS/m3 d, and a shorter HRT, in the range from 25 to 13 days, the process appeared inhibited and/or overloaded, as indicated by the accumulation of volatile fatty acids and long-chain fatty acids and the decline in the methane yield. However, the inhibition was reversible. The nitrogen in the feed, ca. 7.8% of total solids (TS), was organic nitrogen with little ammonia present, whereas in the digested material ammonia accounted for 52-67% (up to 3.8 g/l) of total nitrogen. The TS and VS removals amounted to 76% and 64%, respectively. Our results show that on a continuous basis under the studied conditions and with a loading of up to 0.8 kg VS/m3 d metric ton (wet weight) of the studied waste mixture could yield up to 140 m3 of methane.

Comparison of semi-batch vs. continuously fed anaerobic bioreactors for the treatment of a high-strength, solids-rich pumpkin-processing wastewater.

PubMed

del Agua, Isabel; Usack, Joseph G; Angenent, Largus T

2015-01-01

The objective of this work was to compare two different high-rate anaerobic bioreactor configurations--the anaerobic sequencing batch reactor (ASBR) and the upflow anaerobic solid removal (UASR) reactor--for the treatment of a solid-rich organic wastewater with a high strength. The two, 4.5-L reactors were operated in parallel for close to 100 days under mesophilic conditions (37°C) with non-granular biomass by feeding a pumpkin wastewater with ∼4% solids. The organic loading rate of pumpkin wastewater was increased periodically to a maximum of 8 g COD L(-1) d(-1) by shortening the hydraulic retention time to 5.3 days. Compositional analysis of pumpkin wastewater revealed deficiencies in the trace metal cobalt and alkalinity. With supplementation, the ASBR outperformed the UASR reactor with total chemical oxygen demand (COD) removal efficiencies of 64% and 53%, respectively, achieving a methane yield of 0.27 and 0.20 L CH4 g(-1) COD fed to the ASBR and UASR, respectively. The better performance realized with the ASBR and this specific wastewater was attributed to its semi-batch, dynamic operating conditions rather than the continuous operating conditions of the UASR reactor.

Wheat is more potent than corn or barley for dietary mitigation of enteric methane emissions from dairy cows.

PubMed

Moate, P J; Williams, S R O; Jacobs, J L; Hannah, M C; Beauchemin, K A; Eckard, R J; Wales, W J

2017-09-01

Wheat is the most common concentrate fed to dairy cows in Australia, but few studies have examined the effects of wheat feeding on enteric methane emissions, and no studies have compared the relative potencies of wheat, corn, and barley for their effects on enteric methane production. In this 35-d experiment, 32 Holstein dairy cows were offered 1 of 4 diets: a corn diet (CRN) of 10.0 kg of dry matter (DM)/d of single-rolled corn grain, 1.8 kg of DM/d of canola meal, 0.2 kg of DM/d of minerals, and 11.0 kg of DM/d of chopped alfalfa hay; a wheat diet (WHT) similar to the CRN diet but with the corn replaced by single-rolled wheat; a barley diet (SRB) similar to the CRN diet but with the corn replaced by single-rolled barley; and a barley diet (DRB) similar to the CRN diet but with the corn replaced by double-rolled barley. Individual cow feed intakes, milk yields, and milk compositions were measured daily but reported for the last 5 d of the experiment. During the last 5 d of the experiment, individual cow methane emissions were measured using the SF 6 tracer technique for all cows, and ruminal fluid pH was continuously measured by intraruminal sensors for 3 cows in each treatment group. The average DM intake of cows offered the CRN, WHT, SRB, and DRB diets was 22.2, 21.1, 22.6, and 22.6 kg/d. The mean energy-corrected milk of cows fed the WHT diet was less than that of cows fed the other diets. This occurred because the milk fat percentage of cows fed the WHT diet was significantly less than that of cows fed the other diets. The mean methane emissions and methane yields of cows fed the WHT diet were also significantly less than those of cows fed the other diets. Indeed, the CRN, SRB, and DRB diets were associated with 49, 73, and 78% greater methane emissions, respectively, compared with the emissions from the WHT diet. Methane yield was found to be most strongly related to the minimum daily ruminal fluid pH. This study showed that although the inclusion of wheat in the diet of dairy cows could be an effective strategy for substantially reducing their methane emissions, it also reduced their milk fat percentage and production of milk fat and energy-corrected milk. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Psychrophilic dry anaerobic digestion of dairy cow feces: Long-term operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Massé, Daniel I., E-mail: Daniel.masse@agr.gc.ca; Cata Saady, Noori M.

2015-02-15

Highlights: • Psychrophilic dry anaerobic digestion (PDAD) of cow feces (CF) is feasible. • PDAD of CF is as efficient as mesophilic and thermophilic AD at TCL 21 days. • CF (13–16% TS at OLR 5.0 g TCOD{sub fed} kg{sup −1} inoculum d{sup −1}) yielded 222 ± 27 {sub N}L CH{sub 4} kg{sup −1} VS fed. - Abstract: This paper reports experimental results which demonstrate psychrophilic dry anaerobic digestion of cow feces during long-term operation in sequence batch reactor. Cow feces (13–16% total solids) has been anaerobically digested in 12 successive cycles (252 days) at 21 days treatment cycle lengthmore » (TCL) and temperature of 20 °C using psychrotrophic anaerobic mixed culture. An average specific methane yield (SMY) of 184.9 ± 24.0, 189.9 ± 27.3, and 222 ± 27.7 {sub N}L CH{sub 4} kg{sup −1} of VS fed has been achieved at an organic loading rate of 3.0, 4.0, and 5.0 g TCOD kg{sup −1} inoculum d{sup −1} and TCL of 21 days, respectively. The corresponding substrate to inoculum ratio (SIR) was 0.39 ± 0.06, 0.48 ± .02, 0.53 ± 0.05, respectively. Average methane production rate of 10 ± 1.4 {sub N}L CH{sub 4} kg{sup −1} VS fed d{sup −1} has been obtained. The low concentration of volatile fatty acids indicated that hydrolysis was the reaction limiting step.« less

Enteric methane production and ruminal fermentation from forage brassica diets fed in continuous culture

USDA-ARS?s Scientific Manuscript database

Brassicas provide forage for livestock during the late fall when traditional perennial cool-season forages are not productive. However, little research exists on ruminal fermentation and methane(CH4) production of brassicas fed as forage. A continuous culture fermentor system was used to assess nutr...

Correlating methane production to microbiota in anaerobic digesters fed synthetic wastewater.

PubMed

Venkiteshwaran, K; Milferstedt, K; Hamelin, J; Fujimoto, M; Johnson, M; Zitomer, D H

2017-03-01

A quantitative structure activity relationship (QSAR) between relative abundance values and digester methane production rate was developed. For this, 50 triplicate anaerobic digester sets (150 total digesters) were each seeded with different methanogenic biomass samples obtained from full-scale, engineered methanogenic systems. Although all digesters were operated identically for at least 5 solids retention times (SRTs), their quasi steady-state function varied significantly, with average daily methane production rates ranging from 0.09 ± 0.004 to 1 ± 0.05 L-CH 4 /L R -day (L R  = Liter of reactor volume) (average ± standard deviation). Digester microbial community structure was analyzed using more than 4.1 million partial 16S rRNA gene sequences of Archaea and Bacteria. At the genus level, 1300 operational taxonomic units (OTUs) were observed across all digesters, whereas each digester contained 158 ± 27 OTUs. Digester function did not correlate with typical biomass descriptors such as volatile suspended solids (VSS) concentration, microbial richness, diversity or evenness indices. However, methane production rate did correlate notably with relative abundances of one Archaeal and nine Bacterial OTUs. These relative abundances were used as descriptors to develop a multiple linear regression (MLR) QSAR equation to predict methane production rates solely based on microbial community data. The model explained over 66% of the variance in the experimental data set based on 149 anaerobic digesters with a standard error of 0.12 L-CH 4 /L R -day. This study provides a framework to relate engineered process function and microbial community composition which can be further expanded to include different feed stocks and digester operating conditions in order to develop a more robust QSAR model. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of different liquid anaerobic digestion effluents as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover.

PubMed

Xu, Fuqing; Shi, Jian; Lv, Wen; Yu, Zhongtang; Li, Yebo

2013-01-01

Effluents from three liquid anaerobic digesters, fed with municipal sewage sludge, food waste, or dairy waste, were evaluated as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover in mesophilic reactors. Three feedstock-to-effluent (F/E) ratios (i.e., 2, 4, and 6) were tested for each effluent. At an F/E ratio of 2, the reactor inoculated by dairy waste effluent achieved the highest methane yield of 238.5L/kg VS(feed), while at an F/E ratio of 4, the reactor inoculated by food waste effluent achieved the highest methane yield of 199.6L/kg VS(feed). The microbial population and chemical composition of the three effluents were substantially different. Food waste effluent had the largest population of acetoclastic methanogens, while dairy waste effluent had the largest populations of cellulolytic and xylanolytic bacteria. Dairy waste also had the highest C/N ratio of 8.5 and the highest alkalinity of 19.3g CaCO(3)/kg. The performance of solid-state batch anaerobic digestion reactors was closely related to the microbial status in the liquid anaerobic digestion effluents. Copyright © 2012 Elsevier Ltd. All rights reserved.

The feasibility of trace element supplementation for stable operation of wheat stillage-fed biogas tank reactors.

PubMed

Gustavsson, J; Svensson, B H; Karlsson, A

2011-01-01

The aim of this study was to investigate the effect of trace element supplementation on operation of wheat stillage-fed biogas tank reactors. The stillage used was a residue from bio-ethanol production, containing high levels of sulfate. In biogas production, high sulfate content has been associated with poor process stability in terms of low methane production and accumulation of process intermediates. However, the results of the present study show that this problem can be overcome by trace element supplementations. Four lab-scale wheat stillage-fed biogas tank reactors were operated for 345 days at a hydraulic retention time of 20 days (37 degrees C). It was concluded that daily supplementation with Co (0.5 mg L(-1)), Ni (0.2 mg L(-1)) and Fe (0.5 g L(-1)) were required for maintaining process stability at the organic loading rate of 4.0 g volatile solids L(-1) day(-1).

Quantification of the methane concentration using anaerobic oxidation of methane coupled to extracellular electron transfer

EPA Science Inventory

A biofilm anode acclimated with acetate, acetate+methane, and methane growth media for over three years produced a steady current density of 1.6-2.3 mA/m^2 in a microbial electrochemical cell (MxC) fed with methane as the sole electron donor. Geobacter was the dominant genus for...

Hourly methane production in finishing steers fed at different levels of dry matter intake

USDA-ARS?s Scientific Manuscript database

Methane (CH4) loss from finishing cattle is important as it represents an energy loss that could be used for maintenance and growth, and CH4 is a greenhouse gas with a global warming potential 21 to 25 times that of CO2. Our objectives were to determine hourly CH4 production from growing cattle fed...

Effects of forage source and extruded linseed supplementation on methane emissions from growing dairy cattle of differing body weights.

PubMed

Hammond, K J; Humphries, D J; Crompton, L A; Kirton, P; Reynolds, C K

2015-11-01

Changes in diet carbohydrate amount and type (i.e., starch vs. fiber) and dietary oil supplements can affect ruminant methane emissions. Our objectives were to measure methane emissions, whole-tract digestibility, and energy and nitrogen utilization from growing dairy cattle at 2 body weight (BW) ranges, fed diets containing either high maize silage (MS) or high grass silage (GS), without or with supplemental oil from extruded linseed (ELS). Four Holstein-Friesian heifers aged 13 mo (BW range from start to finish of 382 to 526 kg) were used in experiment 1, whereas 4 lighter heifers aged 12 mo (BW range from start to finish of 292 to 419 kg) were used in experiment 2. Diets were fed as total mixed rations with forage dry matter (DM) containing high MS or high GS and concentrates in proportions (forage:concentrate, DM basis) of either 75:25 (experiment 1) or 60:40 (experiment 2), respectively. Diets were supplemented without or with ELS (Lintec, BOCM Pauls Ltd., Wherstead, UK; 260 g of oil/kg of DM) at 6% of ration DM. Each experiment was a 4 × 4 Latin square design with 33-d periods, with measurements during d 29 to 33 while animals were housed in respiration chambers. Heifers fed MS at a heavier BW (experiment 1) emitted 20% less methane per unit of DM intake (yield) compared with GS (21.4 vs. 26.6, respectively). However, when repeated with heifers of a lower BW (experiment 2), methane yield did not differ between the 2 diets (26.6g/kg of DM intake). Differences in heifer BW had no overall effect on methane emissions, except when expressed as grams per kilogram of digestible organic matter (OMD) intake (32.4 vs. 36.6, heavy vs. light heifers). Heavier heifers fed MS in experiment 1 had a greater DM intake (9.4kg/d) and lower OMD (755 g/kg), but no difference in N utilization (31% of N intake) compared with heifers fed GS (7.9 kg/d and 799 g/kg, respectively). Tissue energy retention was nearly double for heifers fed MS compared with GS in experiment 1 (15 vs. 8% of energy intake, respectively). Heifers fed MS in experiment 2 had similar DM intake (7.2 kg/d) and retention of energy (5% of intake energy) and N (28% of N intake), compared with GS-fed heifers, but OMD was lower (741 vs. 765 g/kg, respectively). No effect of ELS was noted on any of the variables measured, irrespective of animal BW, and this was likely due to the relatively low amount of supplemental oil provided. Differences in heifer BW did not markedly influence dietary effects on methane emissions. Differences in methane yield were attributable to differences in dietary starch and fiber composition associated with forage type and source. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Effects of soybean meal or canola meal on milk production and methane emissions in lactating dairy cows fed grass silage-based diets.

PubMed

Gidlund, H; Hetta, M; Krizsan, S J; Lemosquet, S; Huhtanen, P

2015-11-01

This study evaluated the effects of soybean meal (SBM) and heat-moisture-treated canola meal (TCM) on milk production and methane emissions in dairy cows fed grass silage-based diets. Twenty-eight Swedish Red cows were used in a cyclic change-over experiment with 4 periods of 21 d and with treatments in 2 × 4 factorial arrangement (however, the control diet without supplementary protein was not fed in replicate). The diets were fed ad libitum as a total mixed ration containing 600 g/kg of grass silage and 400 g/kg of concentrates on a dry matter (DM) basis. The concentrate without supplementary protein consisted of crimped barley and premix (312 and 88 g/kg of DM), providing 130 g of dietary crude protein (CP)/kg of DM. The other 6 concentrates were formulated to provide 170, 210, or 250 g of CP/kg of DM by replacing crimped barley with incremental amounts of SBM (50, 100, or 150 g/kg of diet DM) or TCM (70, 140, or 210 g/kg of diet DM). Feed intake was not influenced by dietary CP concentration, but tended to be greater in cows fed TCM diets compared with SBM diets. Milk and milk protein yield increased linearly with dietary CP concentration, with greater responses in cows fed TCM diets compared with SBM diets. Apparent N efficiency (milk N/N intake) decreased linearly with increasing dietary CP concentration and was lower for cows fed SBM diets than cows fed TCM diets. Milk urea concentration increased linearly with increased dietary CP concentration, with greater effects in cows fed SBM diets than in cows fed TCM diets. Plasma concentrations of total AA and essential AA increased with increasing dietary CP concentration, but no differences were observed between the 2 protein sources. Plasma concentrations of Lys, Met, and His were similar for both dietary protein sources. Total methane emissions were not influenced by diet, but emissions per kilogram of DM intake decreased quadratically, with the lowest value observed in cows fed intermediate levels of protein supplementation. Methane emissions per kilogram of energy-corrected milk decreased more when dietary CP concentration increased in TCM diets compared with SBM diets. Overall, replacing SBM with TCM in total mixed rations based on grass silage had beneficial effects on milk production, N efficiency, and methane emissions across a wide range of dietary CP concentrations. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A laboratory investigation of interactions between denitrifying anaerobic methane oxidation (DAMO) and anammox processes in anoxic environments

PubMed Central

Hu, Shihu; Zeng, Raymond J.; Haroon, Mohamed F.; Keller, Jurg; Lant, Paul A.; Tyson, Gene W.; Yuan, Zhiguo

2015-01-01

This study investigates interactions between recently identified denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (anammox) processes in controlled anoxic laboratory reactors. Two reactors were seeded with the same inocula containing DAMO organisms Candidatus Methanoperedens nitroreducens and Candidatus Methylomirabilis oxyfera, and anammox organism Candidatus Kuenenia stuttgartiensis. Both were fed with ammonium and methane, but one was also fed with nitrate and the other with nitrite, providing anoxic environments with different electron acceptors. After steady state reached in several months, the DAMO process became solely/primarily responsible for nitrate reduction while the anammox process became solely responsible for nitrite reduction in both reactors. 16S rRNA gene amplicon sequencing showed that the nitrate-driven DAMO organism M. nitroreducens dominated both the nitrate-fed (~70%) and the nitrite-fed (~26%) reactors, while the nitrite-driven DAMO organism M. oxyfera disappeared in both communities. The elimination of M. oxyfera from both reactors was likely the results of this organism being outcompeted by anammox bacteria for nitrite. K. stuttgartiensis was detected at relatively low levels (1–3%) in both reactors. PMID:25732131

Biomethanation of Harmful Macroalgal Biomass in Leach-Bed Reactor Coupled to Anaerobic Filter: Effect of Water Regime and Filter Media

PubMed Central

Jung, Heejung; Kim, Jaai; Lee, Changsoo

2018-01-01

Ulva is a marine macroalgal genus which causes serious green tides in coastal areas worldwide. This study investigated anaerobic digestion as a way to manage Ulva waste in a leach-bed reactor coupled to an anaerobic filter (LBR-AF). Two LBR-AF systems with different filter media, blast furnace slag grains for R1, and polyvinyl chloride rings for R2, were run at increasing water replacement rates (WRRs). Both achieved efficient volatile solids reduction (68.4–87.1%) and methane yield (148–309 mL/g VS fed) at all WRRs, with the optimal WRR for maximum methane production being 100 mL/d. R1 maintained more stable methanation performance than R2, possibly due to the different surface properties (i.e., biomass retention capacity) of the filter media. Such an effect was also noted in the different behaviors of the LBR and AF between R1 and R2. The molecular analysis results revealed that the development of the microbial community structure in the reactors was primarily determined by the fermentation type, i.e., dry (LBR) or wet (AF). PMID:29701670

Methane production by anaerobic digestion of water hyacinth (Eichhornia crassipes)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klass, D.L.; Ghosh, S.

1980-01-01

Water hyacinth under conventional high-rate digestion conditions exhibited higher CH4 yields and energy recovery efficiencies when grown in sewage-fed lagoons than when grown in a fresh water pond. Mesophilic digestion provided the highest recovery of feed energy in the product gas as CH4, while thermophilic digestion, when operated at sufficiently high loading rates and reduced detention times, gave the highest specific CH4 production rates. CH4 yields, volatile solids reduction, and energy recovery as CH4 from the sewage-grown water hyacinth were in the same range as those observed for other biomass substrates when digested under similar conditions.

Recombination of radiation defects in solid methane: neutron sources and cryo-volcanism on celestial bodies

NASA Astrophysics Data System (ADS)

Kirichek, O.; Savchenko, E. V.; Lawson, C. R.; Khyzhniy, I. V.; Jenkins, D. M.; Uyutnov, S. A.; Bludov, M. A.; Haynes, D. J.

2018-03-01

Physicochemical properties of solid methane exposed to ionizing radiation have attracted significant interest in recent years. Here we present new trends in the study of radiation effects in solid methane. We particularly focus on relaxation phenomena in solid methane pre-irradiated by energetic neutrons and electron beam. We compare experimental results obtained in the temperature range from 10K to 100K with a model based on the assumption that radiolysis defect recombinations happen in two stages, at two different temperatures. In the case of slow heating up of the solid methane sample, irradiated at 10K, the first wave of recombination occurs around 20K with a further second wave taking place between 50 and 60K. We also discuss the role of the recombination mechanisms in “burp” phenomenon discovered by J. Carpenter in the late 1980s. An understanding of these mechanisms is vital for the designing and operation of solid methane moderators used in advanced neutron sources and could also be a possible explanation for the driving forces behind cryo-volcanism on celestial bodies.

Anaerobic digestion of autoclaved and untreated food waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tampio, Elina, E-mail: elina.tampio@mtt.fi; Ervasti, Satu; Paavola, Teija

2014-02-15

Highlights: • Autoclaving decreased the formation of NH4-N and H{sub 2}S during food waste digestion. • Stable digestion was achieved with untreated and autoclaved FW at OLR 6 kg VS/m{sup 3}day. • Use of acclimated inoculum allowed very rapid increases in OLR. • Highest CH{sub 4} yields were observed at OLR 3 kg VS/m{sup 3}day with untreated FW. • Autoclaved FW produced highest CH{sub 4} yields during OLR 4 kgVS/m{sup 3}day. - Abstract: Anaerobic digestion of autoclaved (160 °C, 6.2 bar) and untreated source segregated food waste (FW) was compared over 473 days in semi-continuously fed mesophilic reactors with tracemore » elements supplementation, at organic loading rates (OLRs) of 2, 3, 4 and 6 kg volatile solids (VS)/m{sup 3} d. Methane yields at all OLR were 5–10% higher for untreated FW (maximum 0.483 ± 0.013 m{sup 3} CH{sub 4}/kg VS at 3 kg VS/m{sup 3} d) than autoclaved FW (maximum 0.439 ± 0.020 m{sup 3} CH{sub 4}/kg VS at 4 kg VS/m{sup 3} d). The residual methane potential of both digestates at all OLRs was less than 0.110 m{sup 3} CH{sub 4}/kg VS, indicating efficient methanation in all cases. Use of acclimated inoculum allowed very rapid increases in OLR. Reactors fed on autoclaved FW showed lower ammonium and hydrogen sulphide concentrations, probably due to reduced protein hydrolysis as a result of formation of Maillard compounds. In the current study this reduced biodegradability appears to outweigh any benefit due to thermal hydrolysis of ligno-cellulosic components.« less

Effect of sludge age on methanogenic and glycogen accumulating organisms in an aerobic granular sludge process fed with methanol and acetate

PubMed Central

Pronk, M; Abbas, B; Kleerebezem, R; van Loosdrecht, M C M

2015-01-01

The influence of sludge age on granular sludge formation and microbial population dynamics in a methanol- and acetate-fed aerobic granular sludge system operated at 35°C was investigated. During anaerobic feeding of the reactor, methanol was initially converted to methane by methylotrophic methanogens. These methanogens were able to withstand the relatively long aeration periods. Lowering the anaerobic solid retention time (SRT) from 17 to 8 days enabled selective removal of the methanogens and prevented unwanted methane formation. In absence of methanogens, methanol was converted aerobically, while granule formation remained stable. At high SRT values (51 days), γ-Proteobacteria were responsible for acetate removal through anaerobic uptake and subsequent aerobic growth on storage polymers formed [so called metabolism of glycogen-accumulating organisms (GAO)]. When lowering the SRT (24 days), Defluviicoccus-related organisms (cluster II) belonging to the α-Proteobacteria outcompeted acetate consuming γ-Proteobacteria at 35°C. DNA from the Defluviicoccus-related organisms in cluster II was not extracted by the standard DNA extraction method but with liquid nitrogen, which showed to be more effective. Remarkably, the two GAO types of organisms grew separately in two clearly different types of granules. This work further highlights the potential of aerobic granular sludge systems to effectively influence the microbial communities through sludge age control in order to optimize the wastewater treatment processes. PMID:26059251

Effect of the co-spun anode functional layer on the performance of the direct-methane microtubular solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Meng, Xiuxia; Gong, Xun; Yin, Yimei; Yang, Naitao; Tan, Xiaoyao; Ma, Zi-Feng

2014-02-01

NiO-YSZ/porous YSZ (NiO-YSZ/p-YSZ) dual-layer hollow fibers have been fabricated by a co-spinning-sintering method, on which a dense YSZ films has been formed by a dip-coating and sintering process. A LSM-YSZ ink has been dip-coated on the dense YSZ films as cathode, while the Cu-CeO2 carbon-resistant catalyst has been impregnated in the p-YSZ layer to form double-anode supported micro tubular fuel cells (MT-SOFCs). The thickness of the Ni-YSZ layer, so called anode functional layer (AFL), is controlled from 74 μm to 13 μm by varying the spinning rates of the NiO-YSZ dopes. The maximum power density of an MT-SOFC, which is fabricated based on a thin co-spun AFL, reaches 566 mW cm-2 operated at 850 °C fed with dry methane, and is stably operated for 85 h without power declination.

Optical constants of liquid and solid methane

NASA Technical Reports Server (NTRS)

Martonchik, John V.; Orton, Glenn S.

1994-01-01

The optical constants n(sub r) + in(sub i) of liquid methane and phase 1 solid methane were determined over the entire spectral range by the use of various data sources published in the literature. Kramers-Kronig analyses were performed on the absorption spectra of liquid methane at the boiling point (111 K) and the melting point (90 K) and on the absorption spectra of phase 1 solid methane at the melting point and at 30 K. Measurements of the static dielectric constant at these temperatures and refractive indices determined over limited spectral ranges were used as constraints in the analyses. Applications of methane optical properties to studies of outer solar system bodies are described.

Influence of feeding supplements of almond hulls and ensiled citrus pulp on the milk production, milk composition, and methane emissions of dairy cows.

PubMed

Williams, S R O; Chaves, A V; Deighton, M H; Jacobs, J L; Hannah, M C; Ribaux, B E; Morris, G L; Wales, W J; Moate, P J

2018-03-01

Almond hulls and citrus pulp have been fed to dairy cows with variable responses for milk production, but no information exists on their effect on enteric methane emissions. This experiment examined the effects of dietary supplementation with either almond hulls or ensiled citrus pulp on the milk yield, milk composition, and enteric methane emissions of dairy cows. Thirty-two Holstein dairy cows in mid lactation were offered 1 of 3 diets over a 28-d experiment. Twelve cows received a control (CON) diet, 10 cows a diet containing almond hulls (ALH), and 10 cows a diet containing ensiled citrus pulp (CIT). All cows were offered 6.0 kg of dry matter (DM)/d of crushed corn, 2.0 kg of DM/d of cold-pressed canola, and 0.2 kg of DM/d of a mineral mix. In addition, cows fed the CON diet were offered 14.5 kg of DM/d of alfalfa cubes; cows fed the ALH diet were offered 10.5 kg of DM/d of alfalfa cubes and 4.0 kg of DM/d of almond hulls; and cows on the CIT diet were offered 11.5 kg of DM/d of alfalfa cubes and 3.0 kg of DM/d of ensiled citrus pulp. Milk yield was measured daily and milk composition was measured on 4 d of each week. Individual cow methane emissions were measured by a sulfur hexafluoride tracer technique on d 24 to 28 of the experiment. The mean milk yield of cows fed the CON diet (27.4 kg/d) was greater than the mean milk yield of cows fed the ALH diet (24.6 kg/cow per day), whereas the mean milk yield of cows fed the CIT diet (26.2 kg/cow per day) was not different from the mean milk yield from cows fed the other 2 diets. Dietary treatment did not influence the concentrations of milk fat, protein, and lactose or fat yields, but the mean protein yield from cows fed the CON diet (0.87 kg/d) was greater than that from cows fed the ALH diet (0.78 kg/d) but not different to those fed the CIT diet (0.85 kg/d). In general, we found no differences in the proportion of individual fatty acids in milk. The mean pH of ruminal fluid from cows offered the CON diet was not different to the pH in the ruminal fluids of cows offered the ALH or the CIT diets. The mean methane emissions (g/d) and yields (g/kg of DM intake) were not influenced by dietary treatment. These findings indicate that, although almond hulls and ensiled citrus pulp can be used as a low-cost feed supplement, almond hulls did negatively affect milk production and neither inhibited enteric methane emissions. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Performance of temperature-phased anaerobic digestion (TPAD) system treating dairy cattle wastes.

PubMed

Sung, Shihwu; Santha, Harikishan

2003-04-01

The performance of temperature-phased anaerobic digestion (TPAD) system in the stabilization of dairy cattle wastes at high solids concentrations has never been evaluated, though the process has been established as a feasible alternative to conventional mesophilic processes for the treatment of municipal wastewater sludges. In this study, the TPAD system operating at a retention time of 14 days was subjected to varying total solids (TS) concentrations (3.46-14.54%) of dairy cattle wastes. At TS concentrations lower than 12.20%, corresponding to system volatile solids (VS) loadings in the range of 1.87-5.82 g VS/L/day, the system achieved an average VS removal of 40.2%. The maximum VS destruction of 42.6% was achieved at a TS concentration of 10.35%. Methane recovery from the wastes was consistently within 0.21-0.22 L/g VS fed. There was a drop in the system performance with respect to VS removal and methane recovery at TS concentrations higher than 10.35%. volatile fatty acid/alkalinity ratios less than 0.35 in the thermophilic reactor and 0.10 in the mesophilic reactor were found favorable for stable operation of the system. For the entire range of TS concentrations, the indicator organism counts in the biosolids were within the limits specified by USEPA in 40 CFR Part 503 regulations for Class A designation. After digestion, nearly 80-85% of total phosphorus was associated with the biosolids. Copyright 2002 Elsevier Science Ltd.

High solids co-digestion of food and landscape waste and the potential for ammonia toxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drennan, Margaret F.; DiStefano, Thomas D., E-mail: thomas.distefano@bucknell.edu

Highlights: • We evaluated co-digestion of food and landscape waste with a pilot-scale anaerobic dry digester. • We evaluated reactor performance at 35 °C under low and high organic loading rates. • Performance was stable under low organic loading rate, but declined under high organic loading rate. • Respirometry was employed to investigate potential inhibition due to ammonia. • Landscape waste was unsuitable in increasing the C:N ratio during codigestion. - Abstract: A pilot-scale study was completed to determine the feasibility of high-solids anaerobic digestion (HSAD) of a mixture of food and landscape wastes at a university in central Pennsylvaniamore » (USA). HSAD was stable at low loadings (2 g COD/L-day), but developed inhibitory ammonia concentrations at high loadings (15 g COD/L-day). At low loadings, methane yields were 232 L CH{sub 4}/kg COD fed and 229 L CH{sub 4}/kg VS fed, and at high loadings yields were 211 L CH{sub 4}/kg COD fed and 272 L CH{sub 4}/kg VS fed. Based on characterization and biodegradability studies, food waste appears to be a good candidate for HSAD at low organic loading rates; however, the development of ammonia inhibition at high loading rates suggests that the C:N ratio is too low for use as a single substrate. The relatively low biodegradability of landscape waste as reported herein made it an unsuitable substrate to increase the C:N ratio. Codigestion of food waste with a substrate high in bioavailable carbon is recommended to increase the C:N ratio sufficiently to allow HSAD at loading rates of 15 g COD/L-day.« less

Extraction of soluble substances from organic solid municipal waste to increase methane production.

PubMed

Campuzano, Rosalinda; González-Martínez, Simón

2015-02-01

This work deals with the analysis of the methane production from Mexico City's urban organic wastes after separating soluble from suspended substances. Water was used to extract soluble substances under three different water to waste ratios and after three extraction procedures. Methane production was measured at 35 °C during 21 days using a commercial methane potential testing device. Results indicate that volatile solids extraction increases with dilution rate to a maximum of 40% at 20 °C and to 43% at 93 °C. The extracts methane production increases with the dilution rate as a result of enhanced dissolved solids extraction. The combined (extract and bagasse) methane production reached, in 6 days, 66% of the total methane produced in 21 days. The highest methane production rates were measured during the first six days. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microbial diversity and dynamics during methane production from municipal solid waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bareither, Christopher A., E-mail: christopher.bareither@colostate.edu; Geological Engineering, University of Wisconsin-Madison, Madison, WI 53706; Wolfe, Georgia L., E-mail: gwolfe@wisc.edu

2013-10-15

Highlights: ► Similar bacterial communities developed following different start-up operation. ► Total methanogens in leachate during the decelerated methane phase reflected overall methane yield. ► Created correlations between methanogens, methane yield, and available substrate. ► Predominant bacteria identified with syntrophic polysaccharide degraders. ► Hydrogenotrophic methanogens were dominant in the methane generation process. - Abstract: The objectives of this study were to characterize development of bacterial and archaeal populations during biodegradation of municipal solid waste (MSW) and to link specific methanogens to methane generation. Experiments were conducted in three 0.61-m-diameter by 0.90-m-tall laboratory reactors to simulate MSW bioreactor landfills. Pyrosequencing ofmore » 16S rRNA genes was used to characterize microbial communities in both leachate and solid waste. Microbial assemblages in effluent leachate were similar between reactors during peak methane generation. Specific groups within the Bacteroidetes and Thermatogae phyla were present in all samples and were particularly abundant during peak methane generation. Microbial communities were not similar in leachate and solid fractions assayed at the end of reactor operation; solid waste contained a more abundant bacterial community of cellulose-degrading organisms (e.g., Firmicutes). Specific methanogen populations were assessed using quantitative polymerase chain reaction. Methanomicrobiales, Methanosarcinaceae, and Methanobacteriales were the predominant methanogens in all reactors, with Methanomicrobiales consistently the most abundant. Methanogen growth phases coincided with accelerated methane production, and cumulative methane yield increased with increasing total methanogen abundance. The difference in methanogen populations and corresponding methane yield is attributed to different initial cellulose and hemicellulose contents of the MSW. Higher initial cellulose and hemicellulose contents supported growth of larger methanogen populations that resulted in higher methane yield.« less

Pretreatment of a primary and secondary sludge blend at different thermal hydrolysis temperatures: Impacts on anaerobic digestion, dewatering and filtrate characteristics.

PubMed

Higgins, Matthew J; Beightol, Steven; Mandahar, Ushma; Suzuki, Ryu; Xiao, Steven; Lu, Hung-Wei; Le, Trung; Mah, Joshua; Pathak, Bipin; DeClippeleir, Haydee; Novak, John T; Al-Omari, Ahmed; Murthy, Sudhir N

2017-10-01

A study was performed to evaluate the effect of thermal hydrolysis pretreatment (THP) temperature on subsequent digestion performance and operation, as well as downstream parameters such as dewatering and cake quality. A blend of primary and secondary solids from the Blue Plains treatment plant in Washington, DC was dewatered to about 16% total solids (TS), and thermally hydrolyzed at five different temperatures 130, 140, 150, 160, 170 °C. The thermally hydrolyzed solids were then fed to five separate, 10 L laboratory digesters using the same feed concentration, 10.5% TS and a solids retention time (SRT) of 15 days. The digesters were operated over a six month period to achieve steady state conditions. The higher thermal hydrolysis temperatures generally improved the solids reduction and methane yields by about 5-6% over the temperature range. The increased temperature reduced viscosity of the solids and increased the cake solids after dewatering. The dissolved organic nitrogen and UV absorbance generally increased at the higher THP temperatures. Overall, operating at a higher temperature improved performance with a tradeoff of higher dissolved organic nitrogen and UV adsorbing materials in the return liquor. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modeling of simultaneous anaerobic methane and ammonium oxidation in a membrane biofilm reactor.

PubMed

Chen, Xueming; Guo, Jianhua; Shi, Ying; Hu, Shihu; Yuan, Zhiguo; Ni, Bing-Jie

2014-08-19

Nitrogen removal by using the synergy of denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (Anammox) microorganisms in a membrane biofilm reactor (MBfR) has previously been demonstrated experimentally. In this work, a mathematical model is developed to describe the simultaneous anaerobic methane and ammonium oxidation by DAMO and Anammox microorganisms in an MBfR for the first time. In this model, DAMO archaea convert nitrate, both externally fed and/or produced by Anammox, to nitrite, with methane as the electron donor. Anammox and DAMO bacteria jointly remove the nitrite fed/produced, with ammonium and methane as the electron donor, respectively. The model is successfully calibrated and validated using the long-term (over 400 days) dynamic experimental data from the MBfR, as well as two independent batch tests at different operational stages of the MBfR. The model satisfactorily describes the methane oxidation and nitrogen conversion data from the system. Modeling results show the concentration gradients of methane and nitrogen would cause stratification of the biofilm, where Anammox bacteria mainly grow in the biofilm layer close to the bulk liquid and DAMO organisms attach close to the membrane surface. The low surface methane loadings result in a low fraction of DAMO microorganisms, but the high surface methane loadings would lead to overgrowth of DAMO bacteria, which would compete with Anammox for nitrite and decrease the fraction of Anammox bacteria. The results suggest an optimal methane supply under the given condition should be applied not only to benefit the nitrogen removal but also to avoid potential methane emissions.

Increasing the concentration of linolenic acid in diets fed to Jersey cows in late lactation does not affect methane production

USDA-ARS?s Scientific Manuscript database

Oil and fat products has shown to reduce methane, however, limited research compares different fat sources effects on methane production. A study using 8 multiparous (325 ± 17 DIM) (mean ± SD) lactating dairy cows, was conducted to determine effects of feeding canola/tallow vs. extruded byproduct co...

Co-digestion of solid waste: Towards a simple model to predict methane production.

PubMed

Kouas, Mokhles; Torrijos, Michel; Schmitz, Sabine; Sousbie, Philippe; Sayadi, Sami; Harmand, Jérôme

2018-04-01

Modeling methane production is a key issue for solid waste co-digestion. Here, the effect of a step-wise increase in the organic loading rate (OLR) on reactor performance was investigated, and four new models were evaluated to predict methane yields using data acquired in batch mode. Four co-digestion experiments of mixtures of 2 solid substrates were conducted in semi-continuous mode. Experimental methane yields were always higher than the BMP values of mixtures calculated from the BMP of each substrate, highlighting the importance of endogenous production (methane produced from auto-degradation of microbial community and generated solids). The experimental methane productions under increasing OLRs corresponded well to the modeled data using the model with constant endogenous production and kinetics identified at 80% from total batch time. This model provides a simple and useful tool for technical design consultancies and plant operators to optimize the co-digestion and the choice of the OLRs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Integrated Pressure-Fed Liquid Oxygen / Methane Propulsion Systems - Morpheus Experience, MARE, and Future Applications

NASA Technical Reports Server (NTRS)

Hurlbert, Eric; Morehead, Robert; Melcher, John C.; Atwell, Matt

2016-01-01

An integrated liquid oxygen (LOx) and methane propulsion system where common propellants are fed to the reaction control system and main engines offers advantages in performance, simplicity, reliability, and reusability. LOx/Methane provides new capabilities to use propellants that are manufactured on the Mars surface for ascent return and to integrate with power and life support systems. The clean burning, non-toxic, high vapor pressure propellants provide significant advantages for reliable ignition in a space vacuum, and for reliable safing or purging of a space-based vehicle. The NASA Advanced Exploration Systems (AES) Morpheus lander demonstrated many of these key attributes as it completed over 65 tests including 15 flights through 2014. Morpheus is a prototype of LOx/Methane propellant lander vehicle with a fully integrated propulsion system. The Morpheus lander flight demonstrations led to the proposal to use LOx/Methane for a Discovery class mission, named Moon Aging Regolith Experiment (MARE) to land an in-situ science payload for Southwest Research Institute on the Lunar surface. Lox/Methane is extensible to human spacecraft for many transportation elements of a Mars architecture. This paper discusses LOx/Methane propulsion systems in regards to trade studies, the Morpheus project experience, the MARE NAVIS (NASA Autonomous Vehicle for In-situ Science) lander, and future possible applications. The paper also discusses technology research and development needs for Lox/Methane propulsion systems.

Solid methane in neutron radiation: Cryogenic moderators and cometary cryo volcanism

NASA Astrophysics Data System (ADS)

Kirichek, O.; Lawson, C. R.; Jenkins, D. M.; Ridley, C. J. T.; Haynes, D. J.

2017-12-01

The effect of ionizing radiation on solid methane has previously been an area of interest in the astrophysics community. In the late 1980s this interest was further boosted by the possibility of using solid methane as a moderating medium in spallation neutron sources. Here we present test results of solid methane moderators commissioned at the ISIS neutron source, and compare them with a model based on the theory of thermal explosion. Good agreement between the moderator test data and our model suggests that the process of radiolysis defect recombination happens at two different temperature ranges: the ;lower temperature; recombination process occurs at around 20 K, with the ;higher temperature; process taking place between 50 and 60 K. We discuss consequences of this mechanism for the designing and operation of solid methane moderators used in advanced neutron sources. We also discuss the possible role of radiolysis defect recombination processes in cryo-volcanism on comets, and suggest an application based on this phenomenon.

Methane generation from waste materials

DOEpatents

Samani, Zohrab A.; Hanson, Adrian T.; Macias-Corral, Maritza

2010-03-23

An organic solid waste digester for producing methane from solid waste, the digester comprising a reactor vessel for holding solid waste, a sprinkler system for distributing water, bacteria, and nutrients over and through the solid waste, and a drainage system for capturing leachate that is then recirculated through the sprinkler system.

Simultaneous hydrogen utilization and in situ biogas upgrading in an anaerobic reactor.

PubMed

Luo, Gang; Johansson, Sara; Boe, Kanokwan; Xie, Li; Zhou, Qi; Angelidaki, Irini

2012-04-01

The possibility of converting hydrogen to methane and simultaneous upgrading of biogas was investigated in both batch tests and fully mixed biogas reactor, simultaneously fed with manure and hydrogen. Batch experiments showed that hydrogen could be converted to methane by hydrogenotrophic methanogenesis with conversion of more than 90% of the consumed hydrogen to methane. The hydrogen consumption rates were affected by both P(H₂) (hydrogen partial pressure) and mixing intensity. Inhibition of propionate and butyrate degradation by hydrogen (1 atm) was only observed under high mixing intensity (shaking speed 300 rpm). Continuous addition of hydrogen (flow rate of 28.6 mL/(L/h)) to an anaerobic reactor fed with manure, showed that more than 80% of the hydrogen was utilized. The propionate and butyrate level in the reactor was not significantly affected by the hydrogen addition. The methane production rate of the reactor with H₂ addition was 22% higher, compared to the control reactor only fed with manure. The CO₂ content in the produced biogas was only 15%, while it was 38% in the control reactor. However, the addition of hydrogen resulted in increase of pH (from 8.0 to 8.3) due to the consumption of bicarbonate, which subsequently caused slight inhibition of methanogenesis. Copyright © 2011 Wiley Periodicals, Inc.

Enhancing ethanol production from thermophilic and mesophilic solid digestate using ozone combined with aqueous ammonia pretreatment.

PubMed

Wang, Dianlong; Xi, Jiang; Ai, Ping; Yu, Liang; Zhai, Hong; Yan, Shuiping; Zhang, Yanlin

2016-05-01

Pretreatment with ozone combined with aqueous ammonia was used to recover residual organic carbon from recalcitrant solid digestate for ethanol production after anaerobic digestion (AD) of rice straw. Methane yield of AD at mesophilic and thermophilic conditions, and ethanol production of solid digestate were investigated. The results showed that the methane yield at thermophilic temperature was 72.2% higher than that at mesophilic temperature under the same conditions of 24days and 17% solid concentration. And also the ethanol production efficiency of solid digestate after thermophilic process was 24.3% higher than that of solid digestate after mesophilic process. In this study, the optimal conditions for integrated methane and ethanol processes were determined as 55°C, 17% solid concentration and 24days. 58.6% of glucose conversion, 142.8g/kg of methane yield and 65.2g/kg of ethanol yield were achieved, and the highest net energy balance was calculated as 6416kJ/kg. Copyright © 2016 Elsevier Ltd. All rights reserved.

High-Temperature Quantum-Classical Transition in Solid Methane

NASA Astrophysics Data System (ADS)

Zakharov, A. Yu.; Leont'eva, A. V.; Prokhorov, A. Yu.; Erenburg, A. I.

2017-04-01

Some experimental studies have reported that physical properties of solid methane exhibit a number of anomalies in the temperature interval between 0.5 T _tr and T _tr (T _tr is triple point of methane). This paper contains an attempt of systematization and theoretical interpretation of the observed anomalies.

Exploitation of olive mill wastewater and liquid cow manure for biogas production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dareioti, Margarita A.; Dokianakis, Spyros N.; Stamatelatou, Katerina

2010-10-15

Co-digestion of organic waste streams is an innovative technology for the reduction of methane/greenhouse gas emissions. Different organic substrates are combined to generate a homogeneous mixture as input to the anaerobic reactor in order to increase process performance, realize a more efficient use of equipment and cost-sharing by processing multiple waste streams in a single facility. In this study, the potential of anaerobic digestion for the treatment of a mixture containing olive mill wastewater (OMW) and liquid cow manure (LCM) using a two-stage process has been evaluated by using two continuously stirred tank reactors (CSTRs) under mesophilic conditions (35 {supmore » o}C) in order to separately monitor and control the processes of acidogenesis and methanogenesis. The overall process was studied with a hydraulic retention time (HRT) of 19 days. The digester was continuously fed with an influent composed (v/v) of 20% OMW and 80% LCM. The average removal of dissolved and total COD was 63.2% and 50%, respectively. The volatile solids (VS) removal was 34.2% for the examined mixture of feedstocks operating the system at an overall OLR of 3.63 g CODL{sub reactor}{sup -1}d{sup -1}. Methane production rate at the steady state reached 0.91 L CH{sub 4}L{sub reactor}{sup -1}d{sup -1} or 250.9 L CH{sub 4} at standard temperature and pressure conditions (STP) per kg COD fed to the system.« less

In-situ study of the gas-phase composition and temperature of an intermediate-temperature solid oxide fuel cell anode surface fed by reformate natural gas

NASA Astrophysics Data System (ADS)

Santoni, F.; Silva Mosqueda, D. M.; Pumiglia, D.; Viceconti, E.; Conti, B.; Boigues Muñoz, C.; Bosio, B.; Ulgiati, S.; McPhail, S. J.

2017-12-01

An innovative experimental setup is used for in-depth and in-operando characterization of solid oxide fuel cell anodic processes. This work focuses on the heterogeneous reactions taking place on a 121 cm2 anode-supported cell (ASC) running with a H2, CH4, CO2, CO and steam gas mixture as a fuel, using an operating temperature of 923 K. The results have been obtained by analyzing the gas composition and temperature profiles along the anode surface in different conditions: open circuit voltage (OCV) and under two different current densities, 165 mA cm-2 and 330 mA cm-2, corresponding to 27% and 54% of fuel utilization, respectively. The gas composition and temperature analysis results are consistent, allowing to monitor the evolution of the principal chemical and electrochemical reactions along the anode surface. A possible competition between CO2 and H2O in methane internal reforming is shown under OCV condition and low current density values, leading to two different types of methane reforming: Steam Reforming and Dry Reforming. Under a current load of 40 A, the dominance of exothermic reactions leads to a more marked increase of temperature in the portion of the cell close to the inlet revealing that current density is not uniform along the anode surface.

Passive landfill gas emission - Influence of atmospheric pressure and implications for the operation of methane-oxidising biofilters.

PubMed

Gebert, Julia; Groengroeft, Alexander

2006-01-01

A passively vented landfill site in Northern Germany was monitored for gas emission dynamics through high resolution measurements of landfill gas pressure, flow rate and composition as well as atmospheric pressure and temperature. Landfill gas emission could be directly related to atmospheric pressure changes on all scales as induced by the autooscillation of air, diurnal variations and the passage of pressure highs and lows. Gas flux reversed every 20 h on average, with 50% of emission phases lasting only 10h or less. During gas emission phases, methane loads fed to a connected methane oxidising biofiltration unit varied between near zero and 247 g CH4 h(-1)m(-3) filter material. Emission dynamics not only influenced the amount of methane fed to the biofilter but also the establishment of gas composition profiles within the biofilter, thus being of high relevance for biofilter operation. The duration of the gas emission phase emerged as most significant variable for the distribution of landfill gas components within the biofilter.

In situ Raman and X-ray diffraction studies on the high pressure and temperature stability of methane hydrate up to 55 GPa.

PubMed

Kadobayashi, Hirokazu; Hirai, Hisako; Ohfuji, Hiroaki; Ohtake, Michika; Yamamoto, Yoshitaka

2018-04-28

High-temperature and high-pressure experiments were performed under 2-55 GPa and 298-653 K using in situ Raman spectroscopy and X-ray diffraction combined with externally heated diamond anvil cells to investigate the stability of methane hydrate. Prior to in situ experiments, the typical C-H vibration modes of methane hydrate and their pressure dependence were measured at room temperature using Raman spectroscopy to make a clear discrimination between methane hydrate and solid methane which forms through the decomposition of methane hydrate at high temperature. The sequential in situ Raman spectroscopy and X-ray diffraction revealed that methane hydrate survives up to 633 K and 40.3 GPa and then decomposes into solid methane and ice VII above the conditions. The decomposition curve of methane hydrate estimated by the present experiments is >200 K lower than the melting curves of solid methane and ice VII, and moderately increases with increasing pressure. Our result suggests that although methane hydrate may be an important candidate for major constituents of cool exoplanets and other icy bodies, it is unlikely to be present in the ice mantle of Neptune and Uranus, where the temperature is expected to be far beyond the decomposition temperatures.

In situ Raman and X-ray diffraction studies on the high pressure and temperature stability of methane hydrate up to 55 GPa

NASA Astrophysics Data System (ADS)

Kadobayashi, Hirokazu; Hirai, Hisako; Ohfuji, Hiroaki; Ohtake, Michika; Yamamoto, Yoshitaka

2018-04-01

High-temperature and high-pressure experiments were performed under 2-55 GPa and 298-653 K using in situ Raman spectroscopy and X-ray diffraction combined with externally heated diamond anvil cells to investigate the stability of methane hydrate. Prior to in situ experiments, the typical C-H vibration modes of methane hydrate and their pressure dependence were measured at room temperature using Raman spectroscopy to make a clear discrimination between methane hydrate and solid methane which forms through the decomposition of methane hydrate at high temperature. The sequential in situ Raman spectroscopy and X-ray diffraction revealed that methane hydrate survives up to 633 K and 40.3 GPa and then decomposes into solid methane and ice VII above the conditions. The decomposition curve of methane hydrate estimated by the present experiments is >200 K lower than the melting curves of solid methane and ice VII, and moderately increases with increasing pressure. Our result suggests that although methane hydrate may be an important candidate for major constituents of cool exoplanets and other icy bodies, it is unlikely to be present in the ice mantle of Neptune and Uranus, where the temperature is expected to be far beyond the decomposition temperatures.

Evaluation of anaerobic co-digestion of dairy manure with food wastes via bio-methane potential assay and CSTR reactor.

PubMed

Ye, Yulin; Zamalloa, Carlos; Lin, Hongjian; Yan, Mi; Schmidt, David; Hu, Bo

2015-01-01

The introduction of food wastes into anaerobic digestion (AD) brings a promising scenario of increasing feedstock availability and overall energy production from AD. This study evaluated the biodegradability and methane potential from co-digestion of two typical food wastes, kitchen waste and chicken fat, with dairy manure. For single substrate, the bio-methane potential assays showed that kitchen waste had the highest methane yield of 352 L-CH4 kg(-1)-VS added, 92% more than dairy manure alone. Chicken fat at the same Volatile Solid (VS) level (2 g L(-1)) inhibited bio-methane production. Addition of kitchen waste and chicken fat to a VS percentage of up to 40% improved overall methane yield by 44% and 34%, respectively. Synergistic effect was observed when either combining two or three substrates as AD feedstock, possibly as a result of increased biodegradability of organic materials in chicken fat and kitchen waste compared with dairy manure. Addition of chicken fat improved methane yield more than kitchen waste. However, addition of chicken fat VS over 0.8 g L(-1) should be cautiously done because it may cause reactor failure due to decrease in pH. The maximum methane yield was 425 L-CH4 kg(-1)-VS, achieved at a VS ratio of 2:2:1 for kitchen waste, chicken fat, and dairy manure. Results from batch AD experiment demonstrated that supplementing dairy manure to chicken fat and/or kitchen waste improved alkalinity of substrate due to the inclusion of more titratable bases in dairy manure, and therefore stabilized the methanogenesis and substantially improved biogas yield. A mixture of substrates of kitchen waste, chicken fat, and dairy manure at a ratio of 1:1:3 was fed to a continuously stirred tank reactor operated at organic loading rates of 3.28, 6.55, and 2.18 g-COD L(-1)-day (hydraulic retention time of 20, 10, and 30 days, respectively) under mesophilic condition, and methane production rate reached 0.65, 0.95, and 0.34 L-CH4 L(-1)-reactor-day.

Potential of tannin-rich plants for modulating ruminal microbes and ruminal fermentation in sheep.

PubMed

Rira, M; Morgavi, D P; Archimède, H; Marie-Magdeleine, C; Popova, M; Bousseboua, H; Doreau, M

2015-01-01

The objective of this work was to study nutritional strategies for decreasing methane production by ruminants fed tropical diets, combining in vitro and in vivo methods. The in vitro approach was used to evaluate the dose effect of condensed tannins (CT) contained in leaves of Gliricidia sepium, Leucaena leucocephala, and Manihot esculenta (39, 75, and 92 g CT/kg DM, respectively) on methane production and ruminal fermentation characteristics. Tannin-rich plants (TRP) were incubated for 24 h alone or mixed with a natural grassland hay based on Dichanthium spp. (control plant), so that proportions of TRP were 0, 0.25, 0.5, 0.75, and 1.0. Methane production, VFA concentration, and fermented OM decreased with increased proportions of TRP. Numerical differences on methane production and VFA concentration among TRP sources may be due to differences in their CT content, with greater effects for L. leucocephala and M. esculenta than for G. sepium. Independently of TRP, the response to increasing doses of CT was linear for methane production but quadratic for VFA concentration. As a result, at moderate tannin dose, methane decreased more than VFA. The in vivo trial was conducted to investigate the effect of TRP on different ruminal microbial populations. To this end, 8 rumen-cannulated sheep from 2 breeds (Texel and Blackbelly) were used in two 4 × 4 Latin square designs. Diets were fed ad libitum and were composed of the same feeds used for the in vitro trial: control plant alone or combined with pellets made from TRP leaves at 44% of the diet DM. Compared to TRP, concentration of Ruminococcus flavefaciens was greater for the control diet and concentration of Ruminococcus albus was least for the control diet. The methanogen population was greater for Texel than for Blackbelly. By contrast, TRP-containing diets did not affect protozoa or Fibrobacter succinogenes numbers. Hence, TRP showed potential for mitigating methane production by ruminants. These findings suggest that TRP fed as pellets could be used to decrease methane production.

Dry anaerobic digestion of high solids content dairy manure at high organic loading rates in psychrophilic sequence batch reactor.

PubMed

Massé, Daniel I; Saady, Noori M Cata

2015-05-01

Cow manure with bedding is renewable organic biomass available around the year on dairy farms. Developing efficient and cost-effective psychrophilic dry anaerobic digestion (PDAD) processes could contribute to solving farm-related environmental, energy, and manure management problems in cold-climate regions. This study was to increase the organic loading rate (OLR), fed to a novel psychrophilic (20 °C) dry anaerobic digestion of 27% total solid dairy manure (cow feces and wheat straw) in sequence batch reactor (PDAD-SBR), by 133 to 160%. The PDAD-SBR process operated at treatment cycle length of 21 days and OLR of 7.0 and 8.0 g total chemical oxygen demand (TCOD) kg(-1) inoculum day(-1) (5.2 ± 0.1 and 5.8 ± 0.0 g volatile solids (VS) kg(-1) inoculum day(-1)) for four successive cycles (84 days) produced average specific methane yields (SMYs) of 147.1 ± 17.2 and 143.2 ± 11.7 normalized liters (NL) CH4 kg(-1) VS fed, respectively. PDAD of cow feces and wheat straw is possible with VS-based inoculum-to-substrate ratio of 1.45 at OLR of 8.0 g TCOD kg(-1) inoculum day(-1). Hydrolysis was the limiting step reaction. The VS removal averaged around 57.4 ± 0.5 and 60.5 ± 5.7% at OLR 7.0 and 8.0 g TCOD kg(-1) inoculum day(-1), respectively.

Effects of exogenous aerobic bacteria on methane production and biodegradation of municipal solid waste in bioreactors.

PubMed

Ge, Sai; Liu, Lei; Xue, Qiang; Yuan, Zhiming

2016-09-01

Landfill is the most common and efficient ways of municipal solid waste (MSW) disposal and the landfill biogas, mostly methane, is currently utilized to generate electricity and heat. The aim of this work is to study the effects and the role of exogenous aerobic bacteria mixture (EABM) on methane production and biodegradation of MSW in bioreactors. The results showed that the addition of EABM could effectively enhance hydrolysis and acidogenesis processes of MSW degradation, resulting in 63.95% reduction of volatile solid (VS), the highest methane production rate (89.83Lkg(-1) organic matter) ever recorded and a threefold increase in accumulative methane production (362.9L) than the control (127.1L). In addition, it is demonstrated that white-rot fungi (WRF) might further promote the methane production through highly decomposing lignin, but the lower pH value in leachate and longer acidogenesis duration may cause methane production reduced. The data demonstrated that methane production and biodegradation of MSW in bioreactors could be significantly enhanced by EABM via enhanced hydrolysis and acidogenesis processes, and the results are of great economic importance for the future design and management of landfill. Copyright © 2015 Elsevier Ltd. All rights reserved.

Dynamic effect of total solid content, low substrate/inoculum ratio and particle size on solid-state anaerobic digestion.

PubMed

Motte, J-C; Escudié, R; Bernet, N; Delgenes, J-P; Steyer, J-P; Dumas, C

2013-09-01

Among all the process parameters of solid-state anaerobic digestion (SS-AD), total solid content (TS), inoculation (S/X ratio) and size of the organic solid particles can be optimized to improve methane yield and process stability. To evaluate the effects of each parameter and their interactions on methane production, a three level Box-Behnken experimental design was implemented in SS-AD batch tests degrading wheat straw by adjusting: TS content from 15% to 25%, S/X ratio (in volatile solids) between 28 and 47 and particle size with a mean diameter ranging from 0.1 to 1.4mm. A dynamic analysis of the methane production indicates that the S/X ratio has only an effect during the start-up phase of the SS-AD. During the growing phase, TS content becomes the main parameter governing the methane production and its strong interaction with the particle size suggests the important role of water compartmentation on SS-AD. Copyright © 2013 Elsevier Ltd. All rights reserved.

Novel Anaerobic Wastewater Treatment System for Energy Generation at Forward Operating Bases

DTIC Science & Technology

2016-08-01

AnMBR) technology with clinoptilolite ion exchange and GreenBox™ ammonia electrolysis. The system generates both methane and hydrogen fuels...experimental setup. ................................................ 21 Figure 10. Methane phase semi batch experimental setup, a total of three reactors were...set up for PS + solid, Bioc and ADS methane phase reactors. .................... 21 Figure 11. Dried PS solid for the control, Bioc blend for the

Optimization of methane production in anaerobic co-digestion of poultry litter and wheat straw at different percentages of total solid and volatile solid using a developed response surface model.

PubMed

Shen, Jiacheng; Zhu, Jun

2016-01-01

Poultry litter (PL) can be good feedstock for biogas production using anaerobic digestion. In this study, methane production from batch co-digestion of PL and wheat straw (WS) was investigated for two factors, i.e., total solid (2%, 5%, and 10%) and volatile solid (0, 25, and 50% of WS), constituting a 3 × 3 experimental design. The results showed that the maximum specific methane volume [197 mL (g VS)(‑1)] was achieved at 50% VS from WS at 5% TS level. It was estimated that the inhibitory threshold of free ammonia was about 289 mg L(--1), beyond which reduction of methanogenic activity by at least 54% was observed. The specific methane volume and COD removal can be expressed using two response surface models (R(2) = 0.9570 and 0.9704, respectively). Analysis of variance of the experimental results indicated that the C/N ratio was the most significant factor influencing the specific methane volume and COD removal in the co-digestion of these two materials.

The methane production of poultry slaughtering residues and effects of pre-treatments on the methane production of poultry feather.

PubMed

Salminen, E; Einola, J; Rintala, J

2003-09-01

The biological methane production rate and yield of different poultry slaughtering residues were studied. Poultry offal, blood, and bonemeal were rich in proteins and lipids and showed high methane yields, 0.7-0.9, 0.5, and 0.6-0.7 m3 kg(-1) volatile solids(added), respectively (270-340, 100, and 150-170 m3 ton(-1) wet weight). Blood and bonemeal produced methane rapidly, whereas the methane production of offal was more delayed probably due to long-chain fatty acid inhibition. The length of delay depended on the source and concentration of inoculum and incubation temperature, sewage sludge at 35 degrees C having the shortest delay of a few days, while granular sludge did not produce methane within 94 days of incubation. Feather showed a somewhat lower methane yield, 0.21 m3 kg(-1) volatile solids(added) (50 m3 ton(-1) wet weight). Combined thermal (120 degrees C, 5 min) and enzymatic (commercial alkaline endopeptidase, 2-10 g l(-1)) pre-treatments increased its methane yield by 37 to 51%. Thermal (70-120 degrees C, 5-60 min), chemical (NaOH 2-10 g l(-1), 2-24 h), and enzymatic pre-treatments were less effective, with methane yield increasing by 5 to 32%. Based on the present results, anaerobic digestion of the studied poultry slaughtering residues appears a promising possibility because of the high methane yield and nitrogen content of these residues (8 to 14% N of total solids), whereas pre-treatments were shown to improve the methane production of feather.

Renewable Energy Production from DoD Installation Solid Wastes by Anaerobic Digestion

DTIC Science & Technology

2016-06-01

and purification of methane -rich biogas was conducted at the US Air Force Academy. Cost and performance of the technology with respect to renewable...SUBJECT TERMS Food waste, FOG, solid waste, anaerobic digestion, methane , biogas, biomethane, biogas purification, vehicle fuel, renewable energy...The project demonstrated the ability to digest these wastes in a controlled and predictable manner to maximize the generation of biogas, a methane

Partial oxidation of methane (POM) assisted solid oxide co-electrolysis

DOEpatents

Chen, Fanglin; Wang, Yao

2017-02-21

Methods for simultaneous syngas generation by opposite sides of a solid oxide co-electrolysis cell are provided. The method can comprise exposing a cathode side of the solid oxide co-electrolysis cell to a cathode-side feed stream; supplying electricity to the solid oxide co-electrolysis cell such that the cathode side produces a product stream comprising hydrogen gas and carbon monoxide gas while supplying oxygen ions to an anode side of the solid oxide co-electrolysis cell; and exposing the anode side of the solid oxide co-electrolysis cell to an anode-side feed stream. The cathode-side feed stream comprises water and carbon dioxide, and the anode-side feed stream comprises methane gas such that the methane gas reacts with the oxygen ions to produce hydrogen and carbon monoxide. The cathode-side feed stream can further comprise nitrogen, hydrogen, or a mixture thereof.

An afterburner-powered methane/steam reformer for a solid oxide fuel cells application

NASA Astrophysics Data System (ADS)

Mozdzierz, Marcin; Chalusiak, Maciej; Kimijima, Shinji; Szmyd, Janusz S.; Brus, Grzegorz

2018-04-01

Solid oxide fuel cell (SOFC) systems can be fueled by natural gas when the reforming reaction is conducted in a stack. Due to its maturity and safety, indirect internal reforming is usually used. A strong endothermic methane/steam reforming process needs a large amount of heat, and it is convenient to provide thermal energy by burning the remainders of fuel from a cell. In this work, the mathematical model of afterburner-powered methane/steam reformer is proposed. To analyze the effect of a fuel composition on SOFC performance, the zero-dimensional model of a fuel cell connected with a reformer is formulated. It is shown that the highest efficiency of a solid oxide fuel cell is achieved when the steam-to-methane ratio at the reforming reactor inlet is high.

Nutritive value of methane fermentation residue in diets fed to feedlot steers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, J.M.; Shirley, R.L.; Palmer, A.Z.

1982-12-01

Nutritive value of the methane fermentation residue (MFR) from the effluent of a large scale thermophilic methane generator was determined in diets fed to feedlot steers. The MFR contained 22.2% dry matter and 21.9% crude protein (dry basis). Two diets containing 10.6% (dry basis) MFR were formulated using the Urea Fermentation Potential (UFP) system such that in one diet N was in excess (-1.6 UFP) while in the other diet energy was in excess (+2.6 UFP). These two diets were compared in a California Net Energy trial with a feedlot diet (-.3 UFP) containing the same ingredients except the MFR.more » Six steers were fed in a replicated 3(2) Latin square metabolism trial and 70 steers were fed in a 118-d comparative-slaughter, feedlot trial. Digestibilities of dry matter, organic matter, crude protein, acid detergent fiber, ash, total digestible nutrients (TDN) and metabolizable energy were depressed (all P less than .05) in the MFR-containing diets. Steers fed the MFR-containing diets had lower (P less than .05) rates of gain and increased (P less than .05) feed requirements per unit gain. Net energies for maintenance and gain were slightly lower for the MFR-containing diets than the control diet. Crude protein digestibility for the MFR calculated by difference, for the -UFP and the +UFP diets were 37.8 and 50.7%, while corresponding values for TDN were 28.8 and 12.8%, respectively. Concentrations of potentially toxic elements in kidney, liver and muscle as well as flavor and tenderness of steaks were not affected by feeding MFR.« less

Effect of dietary fiber on microbial activity and microbial gas production in various regions of the gastrointestinal tract of pigs.

PubMed Central

Jensen, B B; Jørgensen, H

1994-01-01

The microbial activity, composition of the gas phase, and gas production rates in the gastrointestinal tract of pigs fed either a low- or a high-fiber diet were investigated. Dense populations of culturable anaerobic bacteria, high ATP concentrations, and high adenylate energy charges were found for the last third of the small intestine, indicating that substantial microbial activity takes place in that portion of the gut. The highest microbial activity (highest bacterium counts, highest ATP concentration, high adenylate energy charge, and low pH) was found in the cecum and proximal colon. Greater microbial activity was found in the stomach and all segments of the hindgut in the pigs fed the high-fiber diet than in the pigs fed the low-fiber diet. Considerable amounts of O2 were found in the stomach (around 5%), while the content of O2 in gas samples taken from all other parts of the gastrointestinal tract was < 1%. The highest concentrations and highest production rates for H2 were found in the last third of the small intestine. No methane could be detected in the stomach or the small intestine. The rate of production and concentration of methane in the cecum and the proximal colon were low, followed by a steady increase in the successive segments of the hindgut. A very good correlation between in vivo and in vitro measurements of methane production was found. The amount of CH4 produced by pigs fed the low-fiber diet was 1.4 liters/day per animal. Substantially larger amounts of CH4 were produced by pigs fed the high-fiber diet (12.5 liters/day)(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8031085

Enteric methane production and ruminal fermentation of forage brassica diets fed in continuous culture

USDA-ARS?s Scientific Manuscript database

The aim of the current study was to determine nutrient digestibility, VFA production, N metabolism, and CH4 production of canola (Brassica napus L.), rapeseed (B. napus L.), turnip (B. rapa L.), and annual ryegrass (Lolium multiflorum Lam.) fed with orchardgrass (Dactylis glomerata L.) in continuous...

Valorisation of biodiesel production wastes: Anaerobic digestion of residual Tetraselmis suecica biomass and co-digestion with glycerol.

PubMed

Santos-Ballardo, David U; Font-Segura, Xavier; Ferrer, Antoni Sánchez; Barrena, Raquel; Rossi, Sergio; Valdez-Ortiz, Angel

2015-03-01

One of the principal opportunity areas in the development of the microalgal biodiesel industry is the energy recovery from the solid microalgal biomass residues to optimise the fuel production. This work reports the cumulative methane yields reached from the anaerobic digestion of the solid microalgal biomass residues using different types of inocula, reporting also the improvement of biogas production using the co-digestion of microalgal biomass with glycerol. Results demonstrate that the solid microalgal biomass residues showed better biogas production using a mesophilic inoculum, reaching almost two-fold higher methane production than under thermophilic conditions. Furthermore, the solid microalgal biomass residues methane production rate showed an increase from 173.78 ± 9.57 to 438.46 ± 40.50 mL of methane per gram of volatile solids, when the co-digestion with glycerol was performed. These results are crucial to improve the energy balance of the biodiesel production from Tetraselmis suecica, as well as proposing an alternative way to treat the wastes derived from the microalgae biodiesel production. © The Author(s) 2015.

Slaughterhouse by-products treatment using anaerobic digestion.

PubMed

Moukazis, Ioannis; Pellera, Frantseska-Maria; Gidarakos, Evangelos

2018-01-01

The objective of the present study is to evaluate the use of animal by-products (ABP) as substrates for anaerobic digestion, aiming at methane production. Specifically, four ABP of Category 2 and 3, namely (i) stomach and rumen, (ii) stomach contents, (iii) breasts and reproductive organs and (iv) bladders and intestines with their contents, were selected. The methane potential of each ABP was initially determined, while the feasibility of anaerobic co-digestion of ABP with two agroindustrial waste, i.e. orange peels and olive leaves was also studied. To this purpose, Biochemical Methane Potential (BMP), as well as semi-continuous assays were respectively conducted. In the latter, the effect of the variation in the organic loading rate (OLR) on methane production was investigated. Results obtained from BMP assays showed that the samples containing breasts and reproductive organs, bladders and intestine, and stomach and rumen, had higher methane potentials of 815, 787 and 759 mLCH 4,STP /gVS, respectively. Moreover, according to the results of the semi-continuous assays, maximum methane yields between 253 and 727mLCH 4 /gVS fed were obtained at an OLR of 0.8gVS/L/d. The only case in which methanogenesis inhibition phenomena, due to increased ammonia concentrations, were observed, was the assay being fed with a mixture of breasts and reproductive organs and orange peels, at the highest OLR. This inhibition phenomenon was attributed to an inappropriate C/N ratio. Copyright © 2017 Elsevier Ltd. All rights reserved.

The hydrolytic stage in high solids temperature phased anaerobic digestion improves the downstream methane production rate.

PubMed

Buffière, P; Dooms, M; Hattou, S; Benbelkacem, H

2018-07-01

The role of the hydrolytic stage in high solids temperature phased anaerobic digestion was investigated with a mixture of cattle slurry and maize silage with variable ratios (100, 70 and 30% volatile solids coming from cattle slurry). It was incubated for 48 h at 37, 55, 65 and 72 °C. Soluble chemical oxygen demand and biochemical methane potential were measured at 0, 24 and 48 h. Higher temperatures improved the amount of solubilized COD, which confirmed previously reported results. Nevertheless, solubilization mostly took place during the first 24 h. The rate of methane production in post-hydrolysis BMPs increased after 48 h hydrolysis time, but not after 24 h. The first order kinetic constant rose by 40% on average. No correlation was observed between soluble COD and downstream methane production rate, indicating a possible modification of the physical structure of the particulate solids during the hydrolytic stage. Copyright © 2018 Elsevier Ltd. All rights reserved.

Optimization and microbial community analysis for production of biogas from solid waste residues of palm oil mill industry by solid-state anaerobic digestion.

PubMed

Suksong, Wantanasak; Kongjan, Prawit; Prasertsan, Poonsuk; Imai, Tsuyoshi; O-Thong, Sompong

2016-08-01

This study investigated the improvement of biogas production from solid-state anaerobic digestion (SS-AD) of oil palm biomass by optimizing of total solids (TS) contents, feedstock to inoculum (F:I) ratios and carbon to nitrogen (C:N) ratios. Highest methane yield from EFB, OPF and OPT of 358, 280 and 324m(3)CH4ton(-1)VS, respectively, was achieved at TS content of 16%, C:N ratio of 30:1 and F:I ratio of 2:1. The main contribution to methane from biomass was the degradation of cellulose and hemicellulose. The highest methane production of 72m(3)CH4ton(-1) biomass was achieved from EFB. Bacteria community structure in SS-AD process of oil palm biomass was dominated by Ruminococcus sp. and Clostridium sp., while archaea community was dominated by Methanoculleus sp. Oil palm biomass has great potential for methane production via SS-AD. Copyright © 2016 Elsevier Ltd. All rights reserved.

Transition mechanism of sH to filled-ice Ih structure of methane hydrate under fixed pressure condition

NASA Astrophysics Data System (ADS)

Kadobayashi, H.; Hirai, H.; Ohfuji, H.; Kojima, Y.; Ohishi, Y.; Hirao, N.; Ohtake, M.; Yamamoto, Y.

2017-10-01

The phase transition mechanism of methane hydrate from sH to filled-ice Ih structure was examined using a combination of time-resolved X-ray diffractometry (XRD) and Raman spectroscopy in conjunction with charge-coupled device (CCD) camera observation under fixed pressure conditions. Prior to time-resolved Raman experiments, the typical C-H vibration modes and their pressure dependence of three methane hydrate structures, fluid methane and solid methane were measured using Raman spectroscopy to distinguish the phase transitions of methane hydrates from decomposition to solid methane and ice VI or VII. Experimental results by XRD, Raman spectroscopy and CCD camera observation revealed that the structural transition of sH to filled-ice Ih occurs through a collapse of the sH framework followed by the release of fluid methane that is then gradually incorporated into the filled-ice Ih to reconstruct its structure. These observations suggest that the phase transition of sH to filled-ice Ih takes place by a typical reconstructive mechanism.

Effects of ensiling treatments on lactic acid production and supplementary methane formation of maize and amaranth--an advanced green biorefining approach.

PubMed

Haag, Nicola Leonard; Nägele, Hans-Joachim; Fritz, Thomas; Oechsner, Hans

2015-02-01

A green biorefinery enables the material and energetic use of biomass via lactic acid and methane production. Different ensiling techniques were applied to maize and amaranth with the aim to increase the amount of lactic acid in the silage. In addition the methane formation potential of the ensiled samples and the remaining solid residues after separating the organic juice were assessed. Treating maize with homofermentative lactic acid bacteria in combination with carbonated lime increased the amount of lactic acid about 91.9%. For amaranth no additional lactic acid production was obtained by treating the raw material. Specific methane yields for the solid residues of amaranth were significantly lower in comparison to the corresponding silages. The most promising treatment resulted in a production of 127.9±4.1 g kg(-1) DM lactic acid and a specific methane yield for the solid residue of 349.5±6.6 lN kg(-1) ODM. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of diet forage source and neutral detergent fiber content on milk production of dairy cattle and methane emissions determined using GreenFeed and respiration chamber techniques.

PubMed

Hammond, K J; Jones, A K; Humphries, D J; Crompton, L A; Reynolds, C K

2016-10-01

Strategies to mitigate greenhouse gas emissions from dairy cattle are unlikely to be adopted if production or profitability is reduced. The primary objective of this study was to examine the effects of high maize silage (MS) versus high grass silage (GS) diets, without or with added neutral detergent fiber (NDF) on milk production and methane emission of dairy cattle, using GreenFeed (GF) or respiration chamber (RC) techniques for methane emission measurements. Experiment 1 was 12wk in duration with a randomized block continuous design and 40 Holstein cows (74d in milk) in free-stall housing, assigned to 1 of 4 dietary treatments (n=10 per treatment), according to calving date, parity, and milk yield. Milk production and dry matter intake (DMI) were measured daily, and milk composition measured weekly, with methane yield (g/kg of DMI) estimated using a GF unit (wk 10 to 12). Experiment 2 was a 4×4 Latin square design with 5-wk periods and 4 dairy cows (114d in milk) fed the same 4 dietary treatments as in experiment 1. Measurements of DMI, milk production, and milk composition occurred in wk 4, and DMI, milk production, and methane yield were measured for 2d in RC during wk 5. Dietary treatments for both experiments were fed as total mixed rations offered ad libitum and containing 500g of silage/kg of dry matter composed (DM basis) of either 75:25 MS:GS (MS) or 25:75 MS:GS (GS), without or with added NDF from chopped straw and soy hulls (+47g of NDF/kg of dry matter). In both experiments, compared with high GS, cows fed high MS had a higher DMI, greater milk production, and lower methane yield (24% lower in experiment 1 using GF and 8% lower in experiment 2 using RC). Added NDF increased (or tended to increase) methane yield for high MS, but not high GS diets. In the separate experiments, the GF and RC methods detected similar dietary treatment effects on methane emission (expressed as g/d and g/kg of DMI), although the magnitude of the differences varied between experiments. Overall methane emission and yield were 448g/d and 20.9g/kg of DMI for experiment 1 using GF and 458g/d and 23.8g/kg of DMI for experiment 2 using RC, respectively. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Effect of sole or combined administration of nitrate and 3-nitro-1-propionic acid on fermentation and Salmonella survivability in alfalfa-fed rumen cultures in vitro

USDA-ARS?s Scientific Manuscript database

Ruminal methanogenesis is a digestive inefficiency resulting in the loss of dietary energy consumed by the host and contributing to environmental methane emission. Nitrate is being investigated as a feed supplement to reduce rumen methane emissions, but safety and efficacy concerns persist. To ass...

Quantifying Methane Abatement Efficiency at Three Municipal Solid Waste Landfills; Final Report

EPA Science Inventory

Measurements were conducted at three municipal solid waste landfills to compare fugitive methane emissions from the landfill cells to the quantity of collected gas (i.e., gas collection efficiency). The measurements were conducted over a multi-week sampling campaign using EPA Oth...

Low-temperature superacid catalysis: Reactions of n - butane and propane catalyzed by iron- and manganese-promoted sulfated zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsz-Keung, Cheung; d`Itri, J.L.; Lange, F.C.

1995-12-31

The primary goal of this project is to evaluate the potential value of solid superacid catalysts of the sulfated zirconia type for light hydrocarbon conversion. The key experiments catalytic testing of the performance of such catalysts in a flow reactor fed with streams containing, for example, n-butane or propane. Fe- and Mn-promoted sulfated zirconia was used to catalyze the conversion of n-butane at atmospheric pressure, 225-450{degrees}C, and n-butane partial pressures in the range of 0.0025-0.01 atm. At temperatures <225{degrees}C, these reactions were accompanied by cracking; at temperatures >350{degrees}C, cracking and isomerization occurred. Catalyst deactivation, resulting at least in part frommore » coke formation, was rapid. The primary cracking products were methane, ethane, ethylene, and propylene. The observation of these products along with an ethane/ethylene molar ratio of nearly 1 at 450{degrees}C is consistent with cracking occurring, at least in part, by the Haag-Dessau mechanism, whereby the strongly acidic catalyst protonates n-butane to give carbonium ions. The rate of methane formation from n-butane cracking catalyzed by Fe- and Mn-promoted sulfated zirconia at 450{degrees}C was about 3 x 10{sup -8} mol/(g of catalyst {center_dot}s). The observation of butanes, pentanes, and methane as products is consistent with Olah superacid chemistry, whereby propane is first protonated by a very strong acid to form a carbonium ion. The carbonium ion then decomposes into methane and an ethyl cation which undergoes oligocondensation reactions with propane to form higher molecular weight alkanes. The results are consistent with the identification of iron- and manganese-promoted sulfated zirconia as a superacid.« less

Optimisation of sewage sludge anaerobic digestion through co-digestion with OFMSW: Effect of collection system and particle size

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silvestre, Gracia; Ainia, Departamento de Medio Ambiente, Bioenergía e Higiene Industrial, Paterna, Valencia; Bonmatí, August

2015-09-15

Highlights: • Methane production rate increased between 56% and 208% during OFMSW–SS codigestion. • The OFMSW particle size reduction from 20 to 8 mm did not affect the methane yield. • OFMSW–SS codigestion promoted β-oxidation and acetoclastic methanogenic activity. • The evolution of specific activity was a feasible tool to control the process. - Abstract: The effect of organic fraction of municipal solid waste (OFMSW) loading rate and particulate size on the sewage sludge (SS) mesophilic anaerobic co-digestion was assessed in continuous stirred tank reactor at hydraulic retention time of 20 days. The SS–OFMSW mixture composed by 54% of themore » volatile solids fed (inlet-VS), at OLR of 3.1 kg{sub COD} m{sup −3} d{sup −1} (1.9 kg{sub VS} m{sup −3} d{sup −1}), showed the highest increment on the volumetric methane production and yield of +200% and +59% respectively, under stable conditions. The effect of particulate size was assessed with the same mixture and same operational conditions but reducing the OFMSW particulate size from 20 mm to 8 mm with the aim to improve the hydrolysis step, but the results showed any influence in the OFMSW particulate size range analysed. In addition, specific biomass activity was assessed at the end of each co-digestion period. Results showed that OFMSW promoted β-oxidation syntrophic acetogens and the acetoclastic methanogens activity; although the last increase of the OFMSW percentage (from 47% to 54% inlet-VS) affected negatively the specific substrate activity, but not inhibitory effect was observed. Therefore, the results obtained in the continuous experiment could be related with some inhibitory or toxic effect and not due to hydrolysis limitation. The specific biomass activity test was demonstrated to be an interesting tool to evaluate and control the co-digestion process, especially when conventional parameters did not explain the behaviour of the biological system.« less

Internal reforming characteristics of cermet supported solid oxide fuel cell using yttria stabilized zirconia fed with partially reformed methane

NASA Astrophysics Data System (ADS)

Momma, Akihiko; Takano, Kiyonami; Tanaka, Yohei; Negishi, Akira; Kato, Ken; Nozaki, Ken; Kato, Tohru; Ichigi, Takenori; Matsuda, Kazuyuki; Ryu, Takashi

In order to investigate the internal reforming characteristics in a cermet supported solid oxide fuel cell (SOFC) using YSZ as the electrolyte, the concentration profiles of the gaseous species along the gas flow direction in the anode were measured. Partially reformed methane using a pre-reformer kept at a constant temperature is supplied to the center of the cell which is operated with a seal-less structure at the gas outlet. The anode gas is sucked in via silica capillaries to the initially evacuated gas tanks. The process is simultaneously carried out using five sampling ports. The sampled gas is analyzed by a gas chromatograph. Most of the measurements are made at the cell temperature (T cell) of 750 °C and at various temperatures of the pre-reformer (T ref) with various fuel utilizations (U f) of the cell. The composition of the fuel at the inlet of the anode was confirmed to be almost the same as that theoretically calculated assuming equilibrium at the temperature of the pre-reformer. The effect of internal reforming in the anode is clearly observed as a steady decrease in the methane concentration along the flow axis. The effect of the water-gas shift reaction is also observed as a decrease in the CO 2 concentration and an increase of CO concentration around the gas inlet region, as the water-gas shift reaction inversely proceeds when T cell is higher than T ref. The diffusion of nitrogen from the seal-less outermost edge is observed, and the diffusion is confirmed to be more significant as U f decreases. The observations are compared with the results obtained by the SOFC supported by lanthanum gallate electrolyte. With respect to the internal reforming performance, the cell investigated here is found to be more effective when compared to the previously reported electrolyte supported cell.

Methane potential of sterilized solid slaughterhouse wastes.

PubMed

Pitk, Peep; Kaparaju, Prasad; Vilu, Raivo

2012-07-01

The aim of the current study was to determine chemical composition and methane potential of Category 2 and 3 solid slaughterhouse wastes rendering products (SSHWRP) viz. melt, decanter sludge, meat and bone meal (MBM), technical fat and flotation sludge from wastewater treatment. Chemical analyses showed that SSHWRP were high in protein and lipids with total solids (TS) content of 96-99%. Methane yields of the SSHWRP were between 390 and 978 m(3) CH(4)/t volatile solids (VS)(added). Based on batch experiments, anaerobic digestion of SSHWRP from the dry rendering process could recover 4.6 times more primary energy than the energy required for the rendering process. Estonia has technological capacity to sterilize all the produced Category 2 and 3 solid slaughterhouse wastes (SSHW) and if separated from Category 1 animal by-products (ABP), it could be further utilized as energy rich input material for anaerobic digestion. Copyright © 2012 Elsevier Ltd. All rights reserved.

Enteric methane emissions and lactational performance of Holstein cows fed different concentrations of coconut oil.

PubMed

Hollmann, M; Powers, W J; Fogiel, A C; Liesman, J S; Bello, N M; Beede, D K

2012-05-01

To determine if dietary medium-chain fatty acids (FA; C(8) to C(14)) may mitigate enteric methane emissions, 24 cows were blocked by body size (n=2) and randomly assigned to 1 sequence of dietary treatments. Diets were fed for 35 d each in 2 consecutive periods. Diets differed in concentrations of coconut oil (CNO; ~75% medium-chain FA): 0.0 (control) or 1.3, 2.7, or 3.3% CNO, dry matter basis. The control diet contained 50% forage (74% from corn silage), 16.5% crude protein (60% from rumen-degradable protein), 34% neutral detergent fiber (NDF; 71% from forage), and 28% starch, dry matter basis. Data and sample collections were from d 29 to 35 in environmentally controlled rooms to measure methane (CH(4)) production. Methane emitted was computed from the difference in concentrations of inlet and outlet air and flux as measured 8 times per day. Control cows emitted 464 g of CH(4)/d, consumed 22.9 kg of DM/d, and produced 34.8 kg of solids-corrected milk/d and 1.3 kg of milk fat/d. Treatment with 1.3, 2.7, or 3.3% dietary CNO reduced CH(4) (449, 291, and 253 g/d, respectively), but concomitantly depressed dry matter intake (21.4, 17.9, and 16.2 kg/d, respectively), solids-corrected milk yield (36.3, 28.4, and 26.8 kg/d, respectively), and milk fat yield (1.4, 0.9, and 0.9 kg/d, respectively). The amount of NDF digested in the total tract decreased with increased dietary CNO concentrations; thus, CH(4) emitted per unit of NDF digested rose from 118 to 128, 153, and 166 g/kg across CNO treatments. Dietary CNO did not significantly affect apparent digestibility of CP but increased apparent starch digestibility from 92 to 95%. No FA C(10) or shorter were detected in feces, and apparent digestibility decreased with increasing FA chain length. Coconut oil concentrations of 2.7 or 3.3% decreased yields of milk FA C(14). The highest milk fat concentration (3.69%; 1.3% CNO) was due to the greatest yields of C(12) to C(16) milk FA. Milk FA concentrations of C(18:2 trans-10,cis-12) were related to increased dietary CNO concentrations and presumably to depressed ruminal NDF digestion. Moderate dietary CNO concentrations (e.g., 1.3%) may benefit lactational performance; however, CNO concentrations greater than or equal to 2.7% depressed dry matter intake, milk yield, milk fat yield, and NDF utilization. If mitigation of enteric CH(4) emissions is due to decreased digestion of dietary NDF, then this will lessen a major advantage of ruminants compared with nonruminants in food-production systems. Thus, CNO has limited use for enteric CH(4) mitigation in lactating dairy cows. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Co-Aromatization of Methane with Olefins: The Role of Inner Pore and External Surface Catalytic Sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yung, Matthew M; He, Peng; Jarvis, Jack

The co-aromatization of methane with olefins is investigated using Ag-Ga/HZSM-5 as the catalyst at 400 degrees C. The presence of methane has a pronounced effect on the product distribution in terms of increased average carbon number and substitution index and decreased aromatic carbon fraction compared with its N2 environment counterpart. The participation of methane during the co-aromatization over the Ag-Ga/HZSM-5 catalyst diminishes as the co-fed olefin feedstock molecule becomes larger, from 1-hexene to 1-octene and 1-decene, in diameter. The effect of suppressed methane participation with larger olefinic molecules is not as significant when Ag-Ga/HY is employed as the catalyst, whichmore » might be attributed to the larger pore size of HY that gives more room to hold olefin and methane molecules within the inner pores and reduces the diffusion limitation of olefin molecules. The effect of olefin feedstock on the methane participation during the co-aromatization over Ag-Ga/HZSM-5 is experimentally evidenced by 13C and 2D NMR. The incorporation of the methane carbon atoms into the phenyl ring of product molecules is reduced significantly with larger co-fed olefins, whereas its incorporation into the substitution groups of the formed aromatic molecules is not notably affected, suggesting that the methane participation in the phenyl ring formation might preferably occur within inner pores, while its incorporation into substitution groups may mainly take place on external catalytic sites. This hypothesis is well supported by the product selectivity obtained over Ag-Ga/HZSM-5 catalysts prepared using conventional ZSM-5, ZSM-5 with the external catalytic sites deactivated, nanosize ZSM-5, ZSM-5 with a micro/meso pore structure and ZSM-5 with the inner pores blocked, and further confirmed by the isotopic labeling studies.« less

Peculiarities of methane clathrate hydrate formation and solid-state deformation, including possible superheating of water ice

USGS Publications Warehouse

Stern, L.A.; Kirby, S.H.; Durham, W.B.

1996-01-01

Slow, constant-volume heating of water ice plus methane gas mixtures forms methane clathrate hydrate by a progressive reaction that occurs at the nascent ice/liquid water interface. As this reaction proceeds, the rate of melting of metastable water ice may be suppressed to allow short-lived superheating of ice to at least 276 kelvin. Plastic flow properties measured on clathrate test specimens are significantly different from those of water ice; under nonhydrostatic stress, methane clathrate undergoes extensive strain hardening and a process of solid-state disproportionation or exsolution at conditions well within its conventional hydrostatic stability field.

Effect of shear on performance and microbial ecology of continuously stirred anaerobic digesters treating animal manure.

PubMed

Hoffmann, Rebecca A; Garcia, Marcelo L; Veskivar, Mehul; Karim, Khursheed; Al-Dahhan, Muthanna H; Angenent, Largus T

2008-05-01

We determined the effect of different mixing intensities on the performance, methanogenic population dynamics, and juxtaposition of syntrophic microbes in anaerobic digesters treating cow manure from a dairy farm. Computer automated radioactive particle tracking in conjunction with computational fluid dynamics was performed to quantify the shear levels locally. Four continuously stirred anaerobic digesters were operated at different mixing intensities of 1,500, 500, 250, and 50 revolutions per min (RPM) over a 260-day period at a temperature of 34 +/- 1 degrees C. Animal manure at a volatile solids (VS) concentration of 50 g/L was fed into the digesters daily at five different organic loading rates between 0.6 and 3.5 g VS/L day. The different mixing intensities had no effect on the biogas production rates and yields at steady-state conditions. A methane yield of 0.241 +/- 0.007 L CH(4)/g VS fed was obtained by pooling the data of all four digesters during steady-state periods. However, digester performance was affected negatively by mixing intensity during startup of the digesters, with lower biogas production rates and higher volatile fatty acids concentrations observed for the 1,500-RPM digester. Despite similar methane production yields and rates, the acetoclastic methanogenic populations were different for the high- and low-intensity mixed digesters with Methanosarcina spp. and Methanosaeta concilii as the predominant methanogens, respectively. For all four digesters, epifluorescence microscopy revealed decreasing microbial floc sizes beginning at week 4 and continuing through week 26 after which no microbial flocs remained. This decrease in size, and subsequent loss of microbial flocs did not, however, produce any long-term upsets in digester performance. Copyright 2007 Wiley Periodicals, Inc.

Solid methane on Triton and Pluto - 3- to 4-micron spectrophotometry

NASA Technical Reports Server (NTRS)

Spencer, John R.; Buie, Marc W.; Bjoraker, Gordon L.

1990-01-01

Methane has been identified in the Pluto/Charon system on the basis of absorption features in the reflectance spectrum at 1.5 and 2.3 microns; attention is presently given to observations of a 3.25 micron-centered deep absorption feature in Triton and Pluto/Charon system reflectance spectra. This absorption may indicate the presence of solid methane, constituting either the dominant surface species or a mixture with a highly transparent substance, such as N2 frost.

Quantification of the methane concentration using anaerobic oxidation of methane coupled to extracellular electron transfer.

PubMed

Gao, Yaohuan; Ryu, Hodon; Rittmann, Bruce E; Hussain, Abid; Lee, Hyung-Sool

2017-10-01

A biofilm anode acclimated with growth media containing acetate, then acetate+methane, and finally methane alone produced electrical current in a microbial electrochemical cell (MxC) fed with methane as the sole electron donor. Geobacter was the dominant genus for the bacterial domain (93%) in the biofilm anode, while methanogens (Methanocorpusculum labreanum and Methanosaeta concilii) accounted for 82% of the total archaeal clones in the biofilm. Fluorescence in situ hybridization (FISH) imaging clearly showed a biofilm of mixed bacteria and archaea, suggesting a syntrophic interaction between them for performing anaerobic oxidation of methane (AOM) in the biofilm anode. Measured cumulative coulombs were linearly correlated to the methane-gas concentration in the range of 10-99.97% (R 2 ≥0.99) when the measurement was sustained for at least 50min Thus, cumulative coulombs over 50min could be used to quantify the methane concentration in gas samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cellulose accessibility and microbial community in solid state anaerobic digestion of rape straw.

PubMed

Tian, Jiang-Hao; Pourcher, Anne-Marie; Bureau, Chrystelle; Peu, Pascal

2017-01-01

Solid state anaerobic digestion (SSAD) with leachate recirculation is an appropriate method for the valorization of agriculture residues. Rape straw is a massively produced residue with considerable biochemical methane potential, but its degradation in SSAD remains poorly understood. A thorough study was conducted to understand the performance of rape straw as feedstock for laboratory solid state anaerobic digesters. We investigated the methane production kinetics of rape straw in relation to cellulose accessibility to cellulase and the microbial community. Improving cellulose accessibility through milling had a positive influence on both the methane production rate and methane yield. The SSAD of rape straw reached 60% of its BMP in a 40-day pilot-scale test. Distinct bacterial communities were observed in digested rape straw and leachate, with Bacteroidales and Sphingobacteriales as the most abundant orders, respectively. Archaeal populations showed no phase preference and increased chronologically. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimization of high solids fed-batch saccharification of sugarcane bagasse based on system viscosity changes.

PubMed

Liu, Yunyun; Xu, Jingliang; Zhang, Yu; Yuan, Zhenhong; Xie, Jun

2015-10-10

Viscosity trends in alkali-pretreated sugarcane bagasse (SCB) slurries undergoing high solids fed-batch enzymatic hydrolysis were measured for a range of solids loading from 15% to 36%. Solids liquefaction times were related to system viscosity changes. The viscosity decreased quickly for low solids loading, and increased with increasing solids content. Fed-batch hydrolysis was initiated with 15% solids loading, and an additional 8%, 7% and 6% were successively added after the system viscosity decreased to stable values to achieve a final solids content of 36%. Two enzyme-adding modes with 8.5FPU/g solid were investigated. The batch mode with all enzyme being added at the beginning of the reaction produced the highest yields, with approximately 231.7g/L total sugars and 134.9g/L glucose being obtained after 96h with nearly 60% of the final glucan conversion rate. This finding indicates that under the right conditions, the fed-batch strategy might be a plausible way to produce high sugars under high solids. Copyright © 2015 Elsevier B.V. All rights reserved.

METHOD FOR PRODUCING ISOTOPIC METHANES FROM LITHIUM CARBONATE AND LITHIUM HYDRIDE

DOEpatents

Frazer, J.W.

1959-10-27

A process is descrlbed for the production of methane and for the production of methane containing isotopes of hydrogen and/or carbon. Finely divided lithium hydrlde and litldum carbonate reactants are mixed in intimate contact and subsequently compacted under pressures of from 5000 to 60,000 psl. The compacted lithium hydride and lithium carbenate reactunts are dispised in a gas collecting apparatus. Subsequently, the compact is heated to a temperature in the range 350 to 400 deg C whereupon a solid-solid reaction takes place and gaseous methane is evolved. The evolved methane is contaminated with gaseous hydrogen and a very small amount of CO/sub 2/; however, the desired methane product is separated from sald impurities by well known chemical processes, e.g., condensation in a cold trap. The product methane contalns isotopes of carbon and hydrogen, the Isotopic composition being determined by the carbon isotopes originally present In the lithium carbonate and the hydrogen isotopes originally present in the lithium hydride.

Impact of dietary starch concentration formulated with two types of corn silage on methane and ammonia emissions in dairy cows

USDA-ARS?s Scientific Manuscript database

The objective of this study was to evaluate methane (CH4) and ammonia (NH3) emissions of lactating dairy cows fed different starch level and corn silage type. After the completion of an 8-wk production study, 48 Holstein cows were allocated to 1 of 4 air-flow controlled chambers (2 cows/chamber) for...

Anaerobic digestion of water hyacinth and sludge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biljetina, R.; Srivastava, V.J.; Chynoweth, D.P.

1986-01-01

The Institute of Gas Technology (IGT) has been operating an experimental test unit (ETU) at the Walt Disney World (WDW) wastewater treatment plant to demonstrate the conversion of water hyacinth and sludge to methane in a solids concentrating (SOLCON) digester. Results from 2 years to operation have confirmed earlier laboratory observations that this digester achieves higher methane yields and solids conversion than those observed in continuous stirred tank reactors. Methane yields as high as 0.49 m/sup 3/ kg/sup -1/ (7.9 SCF/lb) volatile solids added have been obtained during steady-state operation on a blend of water hyacinth and sludge. 9 refs.,more » 5 figs., 5 tabs.« less

Tuneable diode laser gas analyser for methane measurements on a large scale solid oxide fuel cell

NASA Astrophysics Data System (ADS)

Lengden, Michael; Cunningham, Robert; Johnstone, Walter

2011-10-01

A new in-line, real time gas analyser is described that uses tuneable diode laser spectroscopy (TDLS) for the measurement of methane in solid oxide fuel cells. The sensor has been tested on an operating solid oxide fuel cell (SOFC) in order to prove the fast response and accuracy of the technology as compared to a gas chromatograph. The advantages of using a TDLS system for process control in a large-scale, distributed power SOFC unit are described. In future work, the addition of new laser sources and wavelength modulation will allow the simultaneous measurement of methane, water vapour, carbon-dioxide and carbon-monoxide concentrations.

Biomethanization of mixtures of fruits and vegetables solid wastes and sludge from a municipal wastewater treatment plant.

PubMed

Gomez-Lahoz, C; Fernández-Giménez, B; Garcia-Herruzo, F; Rodriguez-Maroto, J M; Vereda-Alonso, C

2007-03-01

The possible management of Fruit and Vegetable Solid Wastes (FVSWs) through their simultaneous digestion with the primary sludge of Municipal Wastewater Treatment plants is investigated. This alternative allows the recovery of energy and a solid product that can be used as an amendment for soils that generated the residue, while is not expensive. Results indicate that the ratio of FVSWs to sludge and the pH control are the main variables determining the methane production and concentration. NaHCO3 was selected to achieve the pH control. The results for a ratio of 50% sludge together with 10 g NaHCO3/kg of residue are among the best obtained, with a methane yield of about 90 L per kg of volatile solids, and a methane concentration of 40% (v/v) of the biogas. A 50% reduction of the total solids; 21% reduction of the volatile solids (in terms of total solids); and a pH value of the sludge, which is 6.9 indicate that the digested sludge can be a good material for soil amendment.

Determination of methane concentrations in shallow ground water and soil gas near Price, Utah

USGS Publications Warehouse

Naftz, David L.; Hadley, Heidi K.; Hunt, Gilbert L.

1998-01-01

Methane gas, commonly referred to as "natural gas," is being produced from coal beds in central Utah (fig. 1) at an increasing rate since the early 1990s. The methane was generated over millions of years during the formation of coal in the area. Coal originates as plant matter that has been deposited in a swamp-like environment and then decays as it is buried and compressed over geologic time. Giant fossilized footprints in the coal provide evidence that dinosaurs roamed and fed among the plentiful plants in these swamps (Hintze, 1979). Methane and carbon dioxide gas and water are produced in the coal as byproducts of coal formation (Sommer and Gloyn, 1993).

Influence of trace substances on methanation catalysts used in dynamic biogas upgrading.

PubMed

Jürgensen, Lars; Ehimen, Ehiaze Augustine; Born, Jens; Holm-Nielsen, Jens Bo; Rooney, David

2015-02-01

The aim of this work was to study the possible deactivation effects of biogas trace ammonia concentrations on methanation catalysts. It was found that small amounts of ammonia led to a slight decrease in the catalyst activity. A decrease in the catalyst deactivation by carbon formation was also observed, with ammonia absorbed on the active catalyst sites. This was via a suppression of the carbon formation and deposition on the catalyst, since it requires a higher number of active sites than for the methanation of carbon oxides. From the paper findings, no special pretreatment for ammonia removal from the biogas fed to a methanation process is required. Copyright © 2014 Elsevier Ltd. All rights reserved.

Anaerobic co-digestion of sewage sludge and food waste.

PubMed

Prabhu, Meghanath S; Mutnuri, Srikanth

2016-04-01

Anaerobic co-digestion of organic matter improves digester operating characteristics and its performance. In the present work, food waste was collected from the institute cafeteria. Two types of sludge (before centrifuge and after centrifuge) were collected from the fluidised bed reactor of the institute treating sewage wastewater. Food waste and sludge were studied for their physico-chemical characteristics, such as pH, chemical oxygen demand, total solids, volatile solids, ammoniacal nitrogen, and total nitrogen. A biomethane potential assay was carried out to find out the optimum mixing ratio of food waste and sludge for anaerobic co-digestion. Results indicated that food waste mixed with sludge in the ratio of 1:2 produced the maximum biogas of 823 ml gVS(-1)(21 days) with an average methane content of 60%. Batch studies were conducted in 5 L lab-glass reactors at a mesophilic temperature. The effect of different substrate loading rates on biogas production was investigated. The mixing ratio of food waste and sludge was 1:2. A loading rate of 1 gVS L d(-1)gave the maximum biogas production of 742 ml g(-1)VS L d(-1)with a methane content of 50%, followed by 2 gVS L d(-1)with biogas of 539 ml g(-1)VS L d(-1) Microbial diversity of the reactor during fed batch studies was investigated by terminal restriction fragment length polymorphism. A pilot-scale co-digestion of food waste and sludge (before centrifuge) indicated the process stability of anaerobic digestion. © The Author(s) 2016.

Elimination of methane in exhaust gas from biogas upgrading process by immobilized methane-oxidizing bacteria.

PubMed

Wu, Ya-Min; Yang, Jing; Fan, Xiao-Lei; Fu, Shan-Fei; Sun, Meng-Ting; Guo, Rong-Bo

2017-05-01

Biogas upgrading is essential for the comprehensive utilization of biogas as substitute of natural gas. However, the methane in the biogas can be fully recovered during the upgrading process of biogas, and the exhaust gas produced during biogas upgrading may contain a very low concentration of methane. If the exhaust gas with low concentration methane releases to atmosphere, it will be harmful to environment. In addition, the utilization of large amounts of digestate produced from biogas plant is another important issue for the development of biogas industry. In this study, solid digestate was used to produce active carbon, which was subsequently used as immobilized material for methane-oxidizing bacteria (MOB) in biofilter. Biofilter with MOB immobilized on active carbon was used to eliminate the methane in exhaust gas from biogas upgrading process. Results showed porous active carbon was successfully made from solid digestate. The final methane elimination capacity of immobilized MOB reached about 13molh -1 m -3 , which was more 4 times higher than that of MOB without immobilization. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of Corn Dried Distiller Grains with Solubles (DDGS) in Dairy Cow Diets on Manure Bioenergy Production Potential

PubMed Central

Massé, Daniel I.; Jarret, Guillaume; Benchaar, Chaouki; Saady, Noori M. Cata

2014-01-01

Simple Summary Among the measures proposed to reduce environmental pollution from the livestock sector, animal nutrition has a strong potential to reduce enteric and manure storages methane emissions. Changes in diet composition also affect the bioenergy potential of dairy manures. Corn dried distillers grains with solubles (DDGS), which are rich in fat, can be included in animal diets to reduce enteric methane (CH4) emissions, while increasing the bioenergy potential of the animal manure during anaerobic digestion. The inclusion of 30% DDGS in the cow diet caused a significant increase of 14% in daily bioenergy production (NL methane day−1·cow−1). abstract The main objective of this study was to obtain scientifically sound data on the bioenergy potential of dairy manures from cows fed different levels of corn dried distillers grains with solubles (DDGS). Three diets differing in corn DDGS content were formulated: 0% corn DDGS (DDGS0; control diet), 10% corn DDGS (DDGS10) and 30% corn DDGS (DDGS30). Bioenergy production was determined in psychrophilic (25 ± 1 °C) sequencing batch reactors (SBRs) fed 3 g COD L−1·day−1 during a two-week feeding period followed by a two-week react period. Compared to the control diet, adding DDGS10 and DDGS30 to the dairy cow diet increased the daily amount of fat excreted in slurry by 29% and 70%, respectively. The addition of DDGS30 increased the cows’ daily production of fresh feces and slurry by 15% and 11%, respectively. Furthermore, the incorporation of DDGS30 in the diet increased the daily amounts of dry matter (DM), volatile solids (VS), neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose by 18%, 18%, 30%, 15% and 53%, respectively, compared to the control diet. While the addition of DDGS did not significantly affect the specific CH4 production per kg VS compared to the control diet, DDGS30 increased the per cow daily CH4 production by 14% compared to the control diet. PMID:26479885

Continuous catalytic decomposition of methane

NASA Technical Reports Server (NTRS)

Clifford, J. E.; Hillenbrand, L. J.; Kim, B. C.; Kolic, E. S.; Zupan, J.

1973-01-01

Water is conserved by employing sequence of reactions whereby 75 percent of methane from Sabatier reaction is decomposed to solid carbon and hydrogen; hydrogen is then separated from residual methane and utilized in usual Sabatier reaction to reduce remaining metabolic carbon dioxide.

Effect of total solids content on methane and volatile fatty acid production in anaerobic digestion of food waste.

PubMed

Liotta, Flavia; d'Antonio, Giuseppe; Esposito, Giovanni; Fabbricino, Massimiliano; van Hullebusch, Eric D; Lens, Piet N L; Pirozzi, Francesco; Pontoni, Ludovico

2014-10-01

This work investigates the role of the moisture content on anaerobic digestion of food waste, as representative of rapidly biodegradable substrates, analysing the role of volatile fatty acid production on process kinetics. A range of total solids from 4.5% to 19.2% is considered in order to compare methane yields and kinetics of reactors operated under wet to dry conditions. The experimental results show a reduction of the specific final methane yield of 4.3% and 40.8% in semi-dry and dry conditions compared with wet conditions. A decreasing trend of the specific initial methane production rate is observed when increasing the total solids concentration. Because of lack of water, volatile fatty acids accumulation occurs during the first step of the process at semi-dry and dry conditions, which is considered to be responsible for the reduction of process kinetic rates. The total volatile fatty acids concentration and speciation are proposed as indicators of process development at different total solids content. © The Author(s) 2014.

Enhancing the solid-state anaerobic digestion of fallen leaves through simultaneous alkaline treatment.

PubMed

Liew, Lo Niee; Shi, Jian; Li, Yebo

2011-10-01

Previous studies have shown that alkali pretreatment prior to anaerobic digestion (AD) can increase the digestibility of lignocellulosic biomass and methane yield. In order to simplify the process and reduce the capital cost, simultaneous alkali treatment and anaerobic digestion was evaluated for methane production from fallen leaves. The highest methane yield of 82 L/kg volatile solids (VS) was obtained at NaOH loading of 3.5% and substrate-to-inoculum (S/I) ratio of 4.1. The greatest enhancement in methane yield was achieved at S/I ratio of 6.2 with NaOH loading of 3.5% which was 24-fold higher than that of the control (without NaOH addition). Reactors at S/I ratio of 8.2 resulted in failure of the AD process. In addition, increasing the total solid (TS) content from 20% to 26% reduced biogas yield by 35% at S/I ratio of 6.2 and NaOH loading of 3.5%. Cellulose and hemicellulose degradation and methane yields are highly related. Copyright © 2011 Elsevier Ltd. All rights reserved.

Using the properties of soil to speed up the start-up process, enhance process stability, and improve the methane content and yield of solid-state anaerobic digestion of alkaline-pretreated poplar processing residues.

PubMed

Yao, Yiqing; Luo, Yang; Li, Tian; Yang, Yingxue; Sheng, Hongmei; Virgo, Nolan; Xiang, Yun; Song, Yuan; Zhang, Hua; An, Lizhe

2014-01-01

Solid-state anaerobic digestion (SS-AD) was initially adopted for the treatment of municipal solid waste. Recently, SS-AD has been increasingly applied to treat lignocellulosic biomass, such as agricultural and forestry residues. However, studies on the SS-AD process are few. In this study, the process performance and methane yield from SS-AD of alkaline-pretreated poplar processing residues (PPRs) were investigated using the properties of soil, such as buffering capacity and nutritional requirements. The results showed that the lignocellulosic structures of the poplar sample were effectively changed by NaOH pretreatment, as indicated by scanning electron microscopy and Fourier transform infrared spectra analysis. The start-up was markedly hastened, and the process stability was enhanced. After NaOH pretreatment, the maximum methane yield (96.1 L/kg volatile solids (VS)) was obtained under a poplar processing residues-to-soil sample (P-to-S) ratio of 2.5:1, which was 29.9% and 36.1% higher than that of PPRs (74.0 L/kg VS) and that of experiments without NaOH pretreatment (70.6 L/kg VS), respectively. During steady state, the increase in the methane content of the experiment with a P-to-S ratio of 2.5:1 was 4.4 to 50.9% higher than that of the PPRs. Degradation of total solids and volatile solids ranged from 19.3 to 33.0% and from 34.9 to 45.9%, respectively. The maximum reductions of cellulose and hemicellulose were 52.6% and 42.9%, respectively, which were in accordance with the maximal methane yield. T 80 for the maximum methane yield for the experiments with NaOH pretreatment was 11.1% shorter than that for the PPRs. Pretreatment with NaOH and addition of soil led to a significant improvement in the process performance and the methane yield of SS-AD of PPRs. The changes in lignocellulosic structures induced by NaOH pretreatment led to an increase in methane yield. For the purpose of practical applications, SS-AD with soil addition is a convenient, economical, and practical technique.

Model development and evaluation of methane potential from anaerobic co-digestion of municipal wastewater sludge and un-dewatered grease trap waste.

PubMed

Yalcinkaya, Sedat; Malina, Joseph F

2015-06-01

The performance of anaerobic co-digestion of municipal wastewater sludge with un-dewatered grease trap waste was assessed using modified biochemical methane potential tests under mesophilic conditions (35°C). Methane potentials, process inhibition and chemical behavior of the process were analyzed at different grease trap waste feed ratios on volatile solids basis. Nonlinear regression analyses of first order reaction and modified Gompertz equations were performed to assist in interpretation of the experimental results. Methane potential of un-dewatered grease trap waste was measured as 606 mL CH4/g VS(added), while methane potential of municipal wastewater sludge was only 223 mL CH4/g VS(added). The results indicated that anaerobic digestion of grease trap waste without dewatering yields less methane potential than concentrated/dewatered grease trap waste because of high wastewater content of un-dewatered grease trap waste. However, anaerobic co-digestion of municipal wastewater sludge and grease trap waste still yields over two times more methane potential and approximately 10% more volatile solids reduction than digestion of municipal wastewater sludge alone. The anaerobic co-digestion process inhibitions were reported at 70% and greater concentrated/dewatered grease trap waste additions on volatile solids basis in previous studies; however, no inhibition was observed at 100% un-dewatered grease trap waste digestion in the present study. These results indicate that anaerobic co-digestion of un-dewatered grease trap waste may reduce the inhibition risk compared to anaerobic co-digestion of concentrated/dewatered grease trap waste. In addition, a mathematical model was developed in this study for the first time to describe the relationship between grease trap waste feed ratio on volatile solids basis and resulting methane potential. Experimental data from the current study as well as previous biochemical methane potential studies were successfully fit to this relationship and allowed estimation of key performance parameters that provide additional insight into the factors affecting biochemical methane potential. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thermophilic methane production from cattle waste.

PubMed Central

Varel, V H; Isaacson, H R; Bryant, M P

1977-01-01

Methane production from waste of cattle fed a finishing diet was investigated, using four 3-liter-working volume anaerobic digestors at 60 degrees C. At 55 degrees C a start-up culture, in which waste was the only source of bacteria, was generated within 8 days and readily adapted to 60 degrees C, where efficiency of methanogenesis was greater. Increasing the temperature from 60 to 65 degrees C tended to drastically lower efficiency. When feed concentrations of volatile solids (VS, organic matter) were increased in steps of 2% after holding for 1 months at a given concentration, the maximum concentrations for efficient fermentation were 8.2, 10.0, 11.6, and 11.6% for the retention times (RT) of 3, 6, 9, and 12 days, respectively. The VS destructions for these and lower feed concentrations were 31 to 37, 36 to 40, 47 to 49 and 51 to 53% for the 3-, 6-, 9-, and 12-day RT digestors, respectively, and the corresponding methane production rates were about 0.16, 0.18, 0.20, and 0.22 liters/day per g of VS in the feed. Gas contained 52 to 57% methane. At the above RT and feed concentrations, alkalinity rose to 5,000 to 7,700 mg of CaCo3 per liter (pH to 7.5 to 7.8), NH3 plus NH4+ to 64 to 90 mM, and total volatile acids to 850 to 2,050 mg/liter as acetate. The 3-day RT digestor was quite stable up to 8.2% feed VS and at this feed concentration produced methane at the very high rate of 4.5 liters/day per liter of digestor. Increasing the percentage of feed VS beyond those values indicated above resulted in greatly decreased organic matter destruction and methane production, variable decrease in pH, and increased alkalinity, ammonia, and total volatile acid concentrations, with propionate being the first to accumulate in large amounts. In a second experiment with another lot of waste, the results were similar. These studies indicate that loading rates can be much higher than those previously thought useful for maximizing methanogenesis from cattle waste. PMID:557954

Seasonal multiphase equilibria in the atmospheres of Titan and Pluto

NASA Astrophysics Data System (ADS)

Tan, S. P.; Kargel, J. S.

2017-12-01

At the extremely low temperatures in Titan's upper troposphere and on Pluto's surface, the atmospheres as a whole are subject to freeze into solid solutions, not pure ices. The presence of the solid phases introduces conditions with rich phase equilibria upon seasonal changes, even if the temperature undergoes only small changes. For the first time, the profile of atmospheric methane in Titan's troposphere will be reproduced complete with the solid solutions. This means that the freezing point, i.e. the altitude where the first solid phase appears, is determined. The seasonal change will also be evaluated both at the equator and the northern polar region. For Pluto, also for the first time, the seasonal solid-vapor equilibria will be evaluated. The fate of the two solid phases, the methane-rich and carbon-monoxide-rich solid solutions, will be analyzed upon temperature and pressure changes. Such investigations are enabled by the development of a molecular-based thermodynamic model for cryogenic chemical systems, referred to as CRYOCHEM, which includes solid solutions in its phase-equilibria calculations. The atmospheres of Titan and Pluto are modeled as ternary gas mixtures: nitrogen-methane-ethane and nitrogen-methane-carbon monoxide, respectively. Calculations using CRYOCHEM can provide us with compositions not only in two-phase equilibria, but also that in three-phase equilibria. Densities of all phases involved will also be calculated. For Titan, density inversion between liquid and solid phases will be identified and presented. In the inversion, the density of solid phase is less than that in the liquid phase. The method and results of this work will be useful for further investigations and modeling on the atmospheres of Titan, Pluto, and other bodies with similar conditions in the Solar System and beyond.

Methane yield in source-sorted organic fraction of municipal solid waste.

PubMed

Davidsson, Asa; Gruvberger, Christopher; Christensen, Thomas H; Hansen, Trine Lund; Jansen, Jes la Cour

2007-01-01

Treating the source-separated organic fraction of municipal solid waste (SS-OFMSW) by anaerobic digestion is considered by many municipalities in Europe as an environmentally friendly means of treating organic waste and simultaneously producing methane gas. Methane yield can be used as a parameter for evaluation of the many different systems that exist for sorting and pre-treating waste. Methane yield from the thermophilic pilot scale digestion of 17 types of domestically SS-OFMSW originating from seven full-scale sorting systems was found. The samples were collected during 1 year using worked-out procedures tested statistically to ensure representative samples. Each waste type was identified by its origin and by pre-sorting, collection and pre-treatment methods. In addition to the pilot scale digestion, all samples were examined by chemical analyses and methane potential measurements. A VS-degradation rate of around 80% and a methane yield of 300-400Nm(3) CH(4)/ton VS(in) were achieved with a retention time of 15 days, corresponding to approximately 70% of the methane potential. The different waste samples gave minor variation in chemical composition and thus also in methane yield and methane potential. This indicates that sorting and collection systems in the present study do not significantly affect the amount of methane produced per VS treated.

Methane mitigation with corn oil and calcium sulfate, responses on whole animal energy and nitrogen balance in dairy cattle consuming reduced-fat distillers grains plus solubles

USDA-ARS?s Scientific Manuscript database

Addition of fat and calcium sulfate to diets fed to ruminants has been shown to reduce methane production, but these factors have not shown effects on energy balance. A study using 16 multiparous (8 Holstein and 8 Jersey) (78 ± 15 DIM) (mean ± SD) lactating dairy cows was conducted to determine how ...

Effects of different fresh-cut forages and their hays on feed intake, digestibility, heat production, and ruminal methane emission by Boer x Spanish goats

USDA-ARS?s Scientific Manuscript database

Twenty-four yearling Boer (87.5%) × Spanish wethers (32.5 ± 0.36 kg body weight) were used in a 32-day experiment to assess effects of frequency of feeding condensed tannin (CT)-containing Sericea lespedeza (SL; Lespedeza cuneata) on ruminal methane emission. Fresh SL (15.3% CT) was fed at 1.3 time...

Mass-radius relationships and constraints on the composition of Pluto

NASA Technical Reports Server (NTRS)

Lupo, M. J.; Lewis, J. S.

1980-01-01

With the new upper limit of Pluto's mass, an upper limit for Pluto's density of 1.74 g/cu cm has been found. Assuming Pluto to be 100% methane, available methane density data can be used to set a lower limit of 0.53 g/cu cm on Pluto's density, thus placing an absolute upper limit of 1909 km on the radius and a lower limit of 0.32 on the albedo. The results of 280 computer models covering a wide range of composition ratios of rock, water ice, and methane ice are reported. Limits are placed on Pluto's silicate content, and a simple spacecraft method for determining Pluto's water content from its density and moment of inertia is given. The low thermal conductivity and strength of solid methane suggest rapid solid-state convection in Pluto's methane layer.

Continuously-stirred anaerobic digester to convert organic wastes into biogas: system setup and basic operation.

PubMed

Usack, Joseph G; Spirito, Catherine M; Angenent, Largus T

2012-07-13

Anaerobic digestion (AD) is a bioprocess that is commonly used to convert complex organic wastes into a useful biogas with methane as the energy carrier. Increasingly, AD is being used in industrial, agricultural, and municipal waste(water) treatment applications. The use of AD technology allows plant operators to reduce waste disposal costs and offset energy utility expenses. In addition to treating organic wastes, energy crops are being converted into the energy carrier methane. As the application of AD technology broadens for the treatment of new substrates and co-substrate mixtures, so does the demand for a reliable testing methodology at the pilot- and laboratory-scale. Anaerobic digestion systems have a variety of configurations, including the continuously stirred tank reactor (CSTR), plug flow (PF), and anaerobic sequencing batch reactor (ASBR) configurations. The CSTR is frequently used in research due to its simplicity in design and operation, but also for its advantages in experimentation. Compared to other configurations, the CSTR provides greater uniformity of system parameters, such as temperature, mixing, chemical concentration, and substrate concentration. Ultimately, when designing a full-scale reactor, the optimum reactor configuration will depend on the character of a given substrate among many other nontechnical considerations. However, all configurations share fundamental design features and operating parameters that render the CSTR appropriate for most preliminary assessments. If researchers and engineers use an influent stream with relatively high concentrations of solids, then lab-scale bioreactor configurations cannot be fed continuously due to plugging problems of lab-scale pumps with solids or settling of solids in tubing. For that scenario with continuous mixing requirements, lab-scale bioreactors are fed periodically and we refer to such configurations as continuously stirred anaerobic digesters (CSADs). This article presents a general methodology for constructing, inoculating, operating, and monitoring a CSAD system for the purpose of testing the suitability of a given organic substrate for long-term anaerobic digestion. The construction section of this article will cover building the lab-scale reactor system. The inoculation section will explain how to create an anaerobic environment suitable for seeding with an active methanogenic inoculum. The operating section will cover operation, maintenance, and troubleshooting. The monitoring section will introduce testing protocols using standard analyses. The use of these measures is necessary for reliable experimental assessments of substrate suitability for AD. This protocol should provide greater protection against a common mistake made in AD studies, which is to conclude that reactor failure was caused by the substrate in use, when really it was improper user operation.

A mass diffusion-based interpretation of the effect of total solids content on solid-state anaerobic digestion of cellulosic biomass.

PubMed

Xu, Fuqing; Wang, Zhi-Wu; Tang, Li; Li, Yebo

2014-09-01

In solid-state anaerobic digestion (SS-AD) of cellulosic biomass, the volumetric methane production rate has often been found to increase with the increase in total solids (TS) content until a threshold is reached, and then to decrease. This phenomenon cannot be explained by conventional understanding derived from liquid anaerobic digestion. This study proposed that the high TS content-caused mass diffusion limitation may be responsible for the observed methane production deterioration. Based on this hypothesis, a new SS-AD model was developed by taking into account the mass diffusion limitation and hydrolysis inhibition. The good agreement between model simulation and the experimental as well as literature data verified that the observed reduction in volumetric methane production rate could be ascribed to hydrolysis inhibition as a result of the mass diffusion limitation in SS-AD. Copyright © 2014 Elsevier Ltd. All rights reserved.

Stable isotope probing of acetate fed anaerobic batch incubations shows a partial resistance of acetoclastic methanogenesis catalyzed by Methanosarcina to sudden increase of ammonia level.

PubMed

Hao, Liping; Lü, Fan; Mazéas, Laurent; Desmond-Le Quéméner, Elie; Madigou, Céline; Guenne, Angéline; Shao, Liming; Bouchez, Théodore; He, Pinjing

2015-02-01

Ammonia inhibition represents a major operational issue for anaerobic digestion. In order to refine our understanding of the terminal catabolic steps in thermophilic anaerobic digestion under ammonia stress, we studied batch thermophilic acetate fed experiments at low (0.26 g L(-1)) and high (7.00 g L(-1)) Total Ammonia Nitrogen concentrations (TAN). Although methane production started immediately for all incubations and resulted in methane yields close to stoichiometric expectations, a 62-72% decrease of methanogenic rate was observed throughout the incubation at 7.00 g L(-1) of TAN compared to 0.26 g L(-1). Stable Isotope Probing analysis of active microbial communities in (13)C-acetate fed experiments coupled to automated ribosomal intergenic spacer analysis and 16S rDNA pyrotag sequencing confirmed that microbial communities were similar for both TAN conditions. At both TAN levels, the (13)C-labeled bacterial community was mainly affiliated to Clostridia-relatives, with OPB54 bacteria being the most abundant sequence in the heavy DNA 16S rDNA pyrotag library. Sequences closely related to Methanosarcina thermophila were also abundantly retrieved in the heavy DNA fractions, showing that this methanogen was still actively assimilating labeled carbon from acetate at free ammonia nitrogen concentrations up to 916 mg L(-1). Stable isotopic signature analysis of biogas, measured in unlabeled acetate fed experiments that were conducted in parallel, confirmed that acetoclastic methanogenic pathway was dominant at both ammonia concentrations. Our work demonstrates that, besides the syntrophic acetate oxidation pathway, acetoclastic methanogenesis catalyzed by Methanosarcina can also play a major role in methane production at high ammonia levels. Copyright © 2014 Elsevier Ltd. All rights reserved.

Thermal Modeling and Management of Solid Oxide Fuel Cells Operating with Internally Reformed Methane

NASA Astrophysics Data System (ADS)

Wu, Yiyang; Shi, Yixiang; Cai, Ningsheng; Ni, Meng

2018-06-01

A detailed three-dimensional mechanistic model of a large-scale solid oxide fuel cell (SOFC) unit running on partially pre-reformed methane is developed. The model considers the coupling effects of chemical and electrochemical reactions, mass transport, momentum and heat transfer in the SOFC unit. After model validation, parametric simulations are conducted to investigate how the methane pre-reforming ratio affects the transport and electrochemistry of the SOFC unit. It is found that the methane steam reforming reaction has a "smoothing effect", which can achieve more uniform distributions of gas compositions, current density and temperature among the cell plane. In the case of 1500 W/m2 power density output, adding 20% methane absorbs 50% of internal heat production inside the cell, reduces the maximum temperature difference inside the cell from 70 K to 22 K and reduces the cathode air supply by 75%, compared to the condition of completely pre-reforming of methane. Under specific operating conditions, the pre-reforming ratio of methane has an optimal range for obtaining a good temperature distribution and good cell performance.

Thermodynamic analysis of biofuels as fuels for high temperature fuel cells

NASA Astrophysics Data System (ADS)

Milewski, Jarosław; Bujalski, Wojciech; Lewandowski, Janusz

2011-11-01

Based on mathematical modeling and numerical simulations, applicativity of various biofuels on high temperature fuel cell performance are presented. Governing equations of high temperature fuel cell modeling are given. Adequate simulators of both solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC) have been done and described. Performance of these fuel cells with different biofuels is shown. Some characteristics are given and described. Advantages and disadvantages of various biofuels from the system performance point of view are pointed out. An analysis of various biofuels as potential fuels for SOFC and MCFC is presented. The results are compared with both methane and hydrogen as the reference fuels. The biofuels are characterized by both lower efficiency and lower fuel utilization factors compared with methane. The presented results are based on a 0D mathematical model in the design point calculation. The governing equations of the model are also presented. Technical and financial analysis of high temperature fuel cells (SOFC and MCFC) are shown. High temperature fuel cells can be fed by biofuels like: biogas, bioethanol, and biomethanol. Operational costs and possible incomes of those installation types were estimated and analyzed. A comparison against classic power generation units is shown. A basic indicator net present value (NPV) for projects was estimated and commented.

Thermodynamic analysis of biofuels as fuels for high temperature fuel cells

NASA Astrophysics Data System (ADS)

Milewski, Jarosław; Bujalski, Wojciech; Lewandowski, Janusz

2013-02-01

Based on mathematical modeling and numerical simulations, applicativity of various biofuels on high temperature fuel cell performance are presented. Governing equations of high temperature fuel cell modeling are given. Adequate simulators of both solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC) have been done and described. Performance of these fuel cells with different biofuels is shown. Some characteristics are given and described. Advantages and disadvantages of various biofuels from the system performance point of view are pointed out. An analysis of various biofuels as potential fuels for SOFC and MCFC is presented. The results are compared with both methane and hydrogen as the reference fuels. The biofuels are characterized by both lower efficiency and lower fuel utilization factors compared with methane. The presented results are based on a 0D mathematical model in the design point calculation. The governing equations of the model are also presented. Technical and financial analysis of high temperature fuel cells (SOFC and MCFC) are shown. High temperature fuel cells can be fed by biofuels like: biogas, bioethanol, and biomethanol. Operational costs and possible incomes of those installation types were estimated and analyzed. A comparison against classic power generation units is shown. A basic indicator net present value (NPV) for projects was estimated and commented.

An integrated microbial electrolysis-anaerobic digestion process combined with pretreatment of wastewater solids to improve hydrogen production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beegle, Jeff R.; Borole, Abhijeet P.

A combined anaerobic digestion (AD) and microbial electrolysis cell (MEC) system, named here as ADMEC, was investigated in this paper to evaluate the energy recovery from pretreated wastewater solids. Alkaline and thermal hydrolysis pretreatment methods increased the solubility of organic compounds present in the raw solids by 25% and 20%, respectively. The soluble phase from pretreatment was separated and used for microbial electrolysis, whereas the insoluble fraction was fed into semi-continuous digesters. The digester effluent was later utilized as a second MEC substrate. The pretreatment had variable effects on AD and MEC performance. The methane content in AD biogas wasmore » higher in pretreated groups, 78.29 ± 2.89% and 73.2 ± 1.79%, for alkaline and thermal, than the control, 50.26 ± 0.53%, but the overall biogas production rates were lower than the control, 20 and 30 mL CH 4 gCOD -1 d -1 for alkaline and thermal compared to 80 mL CH 4 gCOD -1 d -1. The effluent streams from thermally pretreated digesters were the best substrate for microbial electrolysis, in terms of hydrogen production and efficiency. The MECs produced 1.7 ± 0.2 L-H 2 per L per day, 0.3 ± 0.1 L-H 2 per L per day, and 0.29 ± 0.1 L-H 2 per L per day, for thermal, alkaline, and control reactors. The productivity was lower compared to acetate and propionate controls, which yielded 5.79 ± 0.03 L-H 2 per L per day and 3.49 ± 0.10 L-H 2 per L per day, respectively. The pretreatment solubilized fractions were not ideal substrates for microbial electrolysis. Finally, a chemical oxygen demand (COD) mass balance showed that pretreatment shifts the electron flux away from methane and biomass sinks towards hydrogen production.« less

An integrated microbial electrolysis-anaerobic digestion process combined with pretreatment of wastewater solids to improve hydrogen production

DOE PAGES

Beegle, Jeff R.; Borole, Abhijeet P.

2017-08-17

A combined anaerobic digestion (AD) and microbial electrolysis cell (MEC) system, named here as ADMEC, was investigated in this paper to evaluate the energy recovery from pretreated wastewater solids. Alkaline and thermal hydrolysis pretreatment methods increased the solubility of organic compounds present in the raw solids by 25% and 20%, respectively. The soluble phase from pretreatment was separated and used for microbial electrolysis, whereas the insoluble fraction was fed into semi-continuous digesters. The digester effluent was later utilized as a second MEC substrate. The pretreatment had variable effects on AD and MEC performance. The methane content in AD biogas wasmore » higher in pretreated groups, 78.29 ± 2.89% and 73.2 ± 1.79%, for alkaline and thermal, than the control, 50.26 ± 0.53%, but the overall biogas production rates were lower than the control, 20 and 30 mL CH 4 gCOD -1 d -1 for alkaline and thermal compared to 80 mL CH 4 gCOD -1 d -1. The effluent streams from thermally pretreated digesters were the best substrate for microbial electrolysis, in terms of hydrogen production and efficiency. The MECs produced 1.7 ± 0.2 L-H 2 per L per day, 0.3 ± 0.1 L-H 2 per L per day, and 0.29 ± 0.1 L-H 2 per L per day, for thermal, alkaline, and control reactors. The productivity was lower compared to acetate and propionate controls, which yielded 5.79 ± 0.03 L-H 2 per L per day and 3.49 ± 0.10 L-H 2 per L per day, respectively. The pretreatment solubilized fractions were not ideal substrates for microbial electrolysis. Finally, a chemical oxygen demand (COD) mass balance showed that pretreatment shifts the electron flux away from methane and biomass sinks towards hydrogen production.« less

Optimization of fed-batch enzymatic hydrolysis from alkali-pretreated sugarcane bagasse for high-concentration sugar production.

PubMed

Gao, Yueshu; Xu, Jingliang; Yuan, Zhenhong; Zhang, Yu; Liu, Yunyun; Liang, Cuiyi

2014-09-01

Fed-batch enzymatic hydrolysis process from alkali-pretreated sugarcane bagasse was investigated to increase solids loading, produce high-concentration fermentable sugar and finally to reduce the cost of the production process. The optimal initial solids loading, feeding time and quantities were examined. The hydrolysis system was initiated with 12% (w/v) solids loading in flasks, where 7% fresh solids were fed consecutively at 6h, 12h, 24h to get a final solids loading of 33%. All the requested cellulase loading (10 FPU/g substrate) was added completely at the beginning of hydrolysis reaction. After 120 h of hydrolysis, the maximal concentrations of cellobiose, glucose and xylose obtained were 9.376 g/L, 129.50 g/L, 56.03 g/L, respectively. The final total glucan conversion rate attained to 60% from this fed-batch process. Copyright © 2014. Published by Elsevier Ltd.

The conversion of community-derived wastes to methane in a high-rate digester. La conversion des dechets solides municipaux en methane dans un digesteur a rendement eleve

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biljetina, R.; Srivastava, V.J.; Punwani, D.V.

1988-01-01

The Institute of Gas Technology (IGT) has been operating a 4.5-m/sup 3/, anaerobic solids-concentrating digester at the Walt Disney World Resort Complex in Lake Buena Vista, Florida, since January 1984. This digester development work is part of a larger effort that provides effective community waste treatment and disposal options while recovering a valuable methane resources from these wastes. Excellent conversions to methane have been obtained in the digester during 4 years of uninterrupted operation. Data were collected on wastes from experimental municipal wastewater treatment applications, that is, water hyacinths were harvested from secondary wastewater treatment channels and combined with sludgemore » from primary clarifiers to maximize potential methane recoveries in the digester; wastes from agricultural operations, that is, sorghum was selected as a candidate because it represents both a potential energy crop, as well as a waste resource if only portions of the plant are converted after grain production; and wastes from municipal waste collection. Municipal solids waste (MSW) from a commercial resource recovery center was selected. 3 refs., 4 figs., 5 tabs.« less

Maintenance energy requirement of llamas.

PubMed

Carmean, B R; Johnson, K A; Johnson, D E; Johnson, L W

1992-09-01

Five castrated male llamas (mean body weight, 94 kg) were studied in an energy balance trial to determine maintenance energy requirement of llamas. Llamas were fed a 50% oat hay-50% pelleted concentrate diet (2.43 Mcal of metabolizable energy/kg of diet dry matter) at approximately 1.6% of body weight (BW). An 8-day total collection digestion trial was used to determine fecal and urine energy losses. Heat production and methane emissions were determined via indirect respiration calorimetry measurements on each llama fed at the same level of intake as during the digestion trial and subsequently on days 3 and 4 of a period of nonfeeding. Fecal, urine, and methane energy losses of the llamas fed near-maintenance intake were 32.5, 3.5, and 7.1% of gross energy intake, respectively. The postabsorptive metabolic rate, commonly called nonfed (fasting) heat production, was 59.3 kcal/BW0.75. Using a linear relation between postabsorptive and maintenance energy requirement and efficiency of energy use below maintenance of 0.702, metabolizable energy requirement at maintenance was determined to be 84.5 kcal/BW0.75.

Binding of methane to activated mineral surfaces - a methane sink on Mars?

NASA Astrophysics Data System (ADS)

Nørnberg, P.; Knak Jensen, S. J.; Skibsted, J.; Jakobsen, H. J.; ten Kate, I. L.; Gunnlaugsson, H. P.; Merrison, J. P.; Finster, K.; Bak, Ebbe; Iversen, J. J.; Kondrup, J. C.

2015-10-01

Tumbling experiments that simulate the wind erosion of quartz grains in an atmosphere of 13 C-enriched methane are reported. The eroded grains are analyzed by 13C and 29 Si solid-state NMR techniques after several months of tumbling. The analysis shows that methane has reacted with the eroded surface to form covalent Si-CH3 bonds, which stay intact for temperatures up to at least 250oC. These findings offer a model for a methane sink that might explain the fast disappearance of methane on Mars.

Assessment of anaerobic biodegradability of five different solid organic wastes

NASA Astrophysics Data System (ADS)

Kristanto, Gabriel Andari; Asaloei, Huinny

2017-03-01

The concept of waste to energy emerges as an alternative solution to increasing waste generation and energy crisis. In the waste to energy concept, waste will be used to produce renewable energy through thermochemical, biochemical, and physiochemical processes. In an anaerobic digester, organic matter brake-down due to anaerobic bacteria produces methane gas as energy source. The organic waste break-down is affected by various characteristics of waste components, such as organic matter content (C, N, O, H, P), solid contents (TS and VS), nutrients ratio (C/N), and pH. This research aims to analyze biodegradability and potential methane production (CH4) from organic waste largely available in Indonesia. Five solid wastes comprised of fecal sludge, cow rumen, goat farm waste, traditional market waste, and tofu dregs were analyzed which showed tofu dregs as waste with the highest rate of biodegradability compared to others since the tofu dregs do not contain any inhibitor which is lignin, have 2.7%VS, 14 C/N ratios and 97.3% organic matter. The highest cumulative methane production known as Biochemical Methane Potential was achieved by tofu dregs with volume of 77 ml during 30-day experiment which then followed by cow rumen, goat farm waste, and traditional market waste. Subsequently, methane productions were calculated through percentage of COD reduction, which showed the efficiency of 99.1% that indicates complete conversion of the high organic matter into methane.

Anaerobic oxidation of methane coupled to thiosulfate reduction in a biotrickling filter.

PubMed

Cassarini, Chiara; Rene, Eldon R; Bhattarai, Susma; Esposito, Giovanni; Lens, Piet N L

2017-09-01

Microorganisms from an anaerobic methane oxidizing sediment were enriched with methane gas as the substrate in a biotrickling filter (BTF) using thiosulfate as electron acceptor for 213days. Thiosulfate disproportionation to sulfate and sulfide were the dominating sulfur conversion process in the BTF and the sulfide production rate was 0.5mmoll -1 day -1 . A specific group of sulfate reducing bacteria (SRB), belonging to the Desulforsarcina/Desulfococcus group, was enriched in the BTF. The BTF biomass showed maximum sulfate reduction rate (0.38mmoll -1 day -1 ) with methane as sole electron donor, measured in the absence of thiosulfate in the BTF. Therefore, a BTF fed with thiosulfate as electron acceptor can be used to enrich SRB of the DSS group and activate the inoculum for anaerobic oxidation of methane coupled to sulfate reduction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Todd Vander Wall | NREL

Science.gov Websites

and implemented methanogenesis systems for the growth and collection of biogenic methane from municipal solid waste. Following that, he performed in-situ investigations on thermogenic methane from

Effect of starch-based supplementation level combined with oil on intake, performance, and methane emissions of growing Nellore bulls on pasture.

PubMed

Neto, A Jose; Messana, J D; Ribeiro, A F; Vito, E S; Rossi, L G; Berchielli, T T

2015-05-01

Intake of tropical grass forages alone is generally insufficient to avoid nutrition imbalances and reduced animal performance; therefore, supplementation is often recommended. The hypothesis of the present study is that when combined with fat, soybean hulls (SH) could replace corn as a source of energy, reducing methane production without affecting animal performance. This study evaluated the effects of starch-based supplementation level combined with oil on intake, digestibility, performance, and methane emissions of growing Nellore bulls (P = 44; initial BW = 250.69 ± 27 kg) fed cv. Xaraés during the rainy season. There were no interactions between starch level and oil supplementation with regard to intake of DM (P = 0.67), forage DM (P = 0.55), supplement DM (P = 0.14), OM (P = 0.66), CP (P = 0.74), NDF (P = 0.50), ether extract (EE; = 0.47), and GE ( P= 0.68). The intake of EE was greater for animals supplemented with oil than those fed supplements without oil (P < 0.01). There were no interactions between starch level and oil supplementation on digestibility of DM (P= 0.18), OM (P = 0.11), NDF (P= 0.42), and EE (P = 0.14). Moreover, there was interaction between starch and oil supplementation on GE (P < 0.01). Independent of starch level used, the addition of oil decreased the digestibility of OM (P = 0.04) and NDF (P = 0.03). There were no main effects of starch level, oil, or interaction between starch and oil for initial BW (P = 0.10), final BW (P = 0.94), ADG (P = 0.40), feed efficiency (P= 0.37), and carcass gain (P = 0.38). There was no interaction between starch-based supplementation level and oil on methane emissions when expressed in grams per day (P = 0.77), kilograms per year (P = 0.77), grams per kilogram DMI (P = 0.53), and grams per kilogram carcass gain (P= 0.31). There was, however, an interaction (P = 0.04) between starch level and oil on methane emissions when corrected for NDF intake. Additionally, oil decreased enteric methane emission for intake of GE (P = 0.04) and EE (P < 0.01) of animals fed with starch level. Soybean hulls have an estimated feeding value similar to that of corn. The use of oil supplementation may be effective to reduce enteric methane emission of Nellore bulls raised on pasture.

Significance of dissolved methane in effluents of anaerobically treated low strength wastewater and potential for recovery as an energy product: A review.

PubMed

Crone, Brian C; Garland, Jay L; Sorial, George A; Vane, Leland M

2016-11-01

The need for energy efficient Domestic Wastewater (DWW) treatment is increasing annually with population growth and expanding global energy demand. Anaerobic treatment of low strength DWW produces methane which can be used to as an energy product. Temperature sensitivity, low removal efficiencies (Chemical Oxygen Demand (COD), Suspended Solids (SS), and Nutrients), alkalinity demand, and potential greenhouse gas (GHG) emissions have limited its application to warmer climates. Although well designed anaerobic Membrane Bioreactors (AnMBRs) are able to effectively treat DWW at psychrophilic temperatures (10-30 °C), lower temperatures increase methane solubility leading to increased energy losses in the form of dissolved methane in the effluent. Estimates of dissolved methane losses are typically based on concentrations calculated using Henry's Law but advection limitations can lead to supersaturation of methane between 1.34 and 6.9 times equilibrium concentrations and 11-100% of generated methane being lost in the effluent. In well mixed systems such as AnMBRs which use biogas sparging to control membrane fouling, actual concentrations approach equilibrium values. Non-porous membranes have been used to recover up to 92.6% of dissolved methane and well suited for degassing effluents of Upflow Anaerobic Sludge Blanket (UASB) reactors which have considerable solids and organic contents and can cause pore wetting and clogging in microporous membrane modules. Microporous membranes can recover up to 98.9% of dissolved methane in AnMBR effluents which have low COD and SS concentrations. Sequential Down-flow Hanging Sponge (DHS) reactors have been used to recover between 57 and 88% of dissolved methane from Upflow Anaerobic Sludge Blanket (UASB) reactor effluent at concentrations of greater than 30% and oxidize the rest for a 99% removal of total dissolved methane. They can also remove 90% of suspended solids and COD in UASB effluents and produce a high quality effluent. In situ degassing can increase process stability, COD removal, biomass retention, and headspace methane concentrations. A model for estimating energy consumption associated with membrane-based dissolved methane recovery predicts that recovered dissolved and headspace methane may provide all the energy required for operation of an anaerobic system treating DWW at psychrophilic temperatures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Pretreatment of food waste with high voltage pulse discharge towards methane production enhancement.

PubMed

Zou, Lianpei; Ma, Chaonan; Liu, Jianyong; Li, Mingfei; Ye, Min; Qian, Guangren

2016-12-01

Anaerobic batch tests were performed to investigate the methane production enhancement and solid transformation rates from food waste (FW) by high voltage pulse discharge (HVPD) pretreatment. The total cumulative methane production with HVPD pretreatment was 134% higher than that of the control. The final volatile solids transformation rates of FW with and without HVPD pretreatment were 54.3% and 32.3%, respectively. Comparison study on HVPD pretreatment with acid, alkali and ultrasonic pretreatments showed that the methane production and COD removal rates of FW pretreated with HVPD were more than 100% higher than the control, but only about 50% higher can be obtained with other pretreatments. HVPD pretreatment could be a promising pretreatment method in the application of energy recovery from FW. Copyright © 2016 Elsevier Ltd. All rights reserved.

High-solid Anaerobic Co-digestion of Sewage Sludge and Cattle Manure: The Effects of Volatile Solid Ratio and pH

PubMed Central

Dai, Xiaohu; Chen, Yang; Zhang, Dong; Yi, Jing

2016-01-01

High-solid anaerobic digestion is an attractive solution to the problem of sewage sludge disposal. One method that can be used to enhance the production of volatile fatty acids (VFAs) and the generation of methane from anaerobic digestion involves combining an alkaline pretreatment step with the synergistic effects of sewage sludge and cattle manure co-digestion, which improves the activity of key enzymes and microorganisms in the anaerobic co-digestion system to promote the digestion of organic waste. In this study, we describe an efficient strategy that involves adjusting the volatile solid (VS) ratio (sewage sludge/cattle manure: 3/7) and initial pH (9.0) to improve VFA production and methane generation from the co-digestion of sludge and manure. The experimental results indicate that the maximum VFA production was 98.33 g/kg-TS (total solid) at the optimal conditions. Furthermore, methane generation in a long-term semi-continuously operated reactor (at a VS ratio of 3/7 and pH of 9.0) was greater than 120.0 L/kg-TS. PMID:27725704

High-solid Anaerobic Co-digestion of Sewage Sludge and Cattle Manure: The Effects of Volatile Solid Ratio and pH

NASA Astrophysics Data System (ADS)

Dai, Xiaohu; Chen, Yang; Zhang, Dong; Yi, Jing

2016-10-01

High-solid anaerobic digestion is an attractive solution to the problem of sewage sludge disposal. One method that can be used to enhance the production of volatile fatty acids (VFAs) and the generation of methane from anaerobic digestion involves combining an alkaline pretreatment step with the synergistic effects of sewage sludge and cattle manure co-digestion, which improves the activity of key enzymes and microorganisms in the anaerobic co-digestion system to promote the digestion of organic waste. In this study, we describe an efficient strategy that involves adjusting the volatile solid (VS) ratio (sewage sludge/cattle manure: 3/7) and initial pH (9.0) to improve VFA production and methane generation from the co-digestion of sludge and manure. The experimental results indicate that the maximum VFA production was 98.33 g/kg-TS (total solid) at the optimal conditions. Furthermore, methane generation in a long-term semi-continuously operated reactor (at a VS ratio of 3/7 and pH of 9.0) was greater than 120.0 L/kg-TS.

Green plants as solar energy converters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1976-06-01

A survey covers the potential of energy production from biomass and solid wastes; various processes for the combustion of wastes, such as the co-combustion of solid waste and sewage sludge at the St. Paul/Seneca Treatment Plant Sludge Incinerator; various biological processes for the conversion of solid wastes to fuel such as the Institute of Gas Technology 400 l. digestor for the biogasification of municipal solid waste and sewage solids to a methane-rich product gas; the use of industrial wastes for fuel, such as slash and mill residues used as fuel in lumber mills; the biogasification of animal wastes by usingmore » small-scale on-site digesters to produce methane gas for cooking and lighting; energy farming methods, such as growing giant California kelp, sargassum, and plankton as suitable feedstock for the production of methane, fertilizers, and food; problems, such as the possible alteration of the reflectivity of large areas of the earth's surface by rapidly growing plants raised for biomass; and benefits such as the reduction in air, water, and land pollution associated with the use of wastes and biomass grown especially for energy.« less

Kinetics of (reversible) internal reforming of methane in solid oxide fuel cells under stationary and APU conditions

NASA Astrophysics Data System (ADS)

Timmermann, H.; Sawady, W.; Reimert, R.; Ivers-Tiffée, E.

The internal reforming of methane in a solid oxide fuel cell (SOFC) is investigated and modeled for flow conditions relevant to operation. To this end, measurements are performed on anode-supported cells (ASC), thereby varying gas composition (y CO = 4-15%, yH2 = 5 - 17 % , yCO2 = 6 - 18 % , yH2O = 2 - 30 % , yCH4 = 0.1 - 20 %) and temperature (600-850 °C). In this way, operating conditions for both stationary applications (methane-rich pre-reformate) as well as for auxiliary power unit (APU) applications (diesel-POX reformate) are represented. The reforming reaction is monitored in five different positions alongside the anodic gas channel by means of gas chromatography. It is shown that methane is converted in the flow field for methane-rich gas compositions, whereas under operation with diesel reformate the direction of the reaction is reversed for temperatures below 675 °C, i.e. (exothermic) methanation occurs along the anode. Using a reaction model, a rate equation for reforming could be derived which is also valid in the case of methanation. By introducing this equation into the reaction model the methane conversion along a catalytically active Ni-YSZ cermet SOFC anode can be simulated for the operating conditions specified above.

Steam Methane Reformation Testing for Air-Independent Solid Oxide Fuel Cell Systems

NASA Technical Reports Server (NTRS)

Mwara, Kamwana N.

2015-01-01

Recently, NASA has been looking into utilizing landers that can be propelled by LOX-CH (sub 4), to be used for long duration missions. Using landers that utilize such propellants, also provides the opportunity to use solid oxide fuel cells as a power option, especially since they are able to process methane into a reactant through fuel reformation. One type of reformation, called steam methane reformation, is a process to reform methane into a hydrogen-rich product by reacting methane and steam (fuel cell exhaust) over a catalyst. A steam methane reformation system could potentially use the fuel cell's own exhaust to create a reactant stream that is hydrogen-rich, and requires less internal reforming of the incoming methane. Also, steam reformation may hold some advantages over other types of reforming, such as partial oxidation (PROX) reformation. Steam reformation does not require oxygen, while up to 25 percent can be lost in PROX reformation due to unusable CO (sub 2) reformation. NASA's Johnson Space Center has conducted various phases of steam methane reformation testing, as a viable solution for in-space reformation. This has included using two different types of catalysts, developing a custom reformer, and optimizing the test system to find the optimal performance parameters and operating conditions.

Significance of dissolved methane in effluents of anaerobically ...

EPA Pesticide Factsheets

The need for energy efficient Domestic Wastewater (DWW) treatment is increasing annually with population growth and expanding global energy demand. Anaerobic treatment of low strength DWW produces methane which can be used to as an energy product. Temperature sensitivity, low removal efficiencies (Chemical Oxygen Demand (COD), Suspended Solids (SS), and Nutrients), alkalinity demand, and potential greenhouse gas (GHG) emissions have limited its application to warmer climates. Although well designed anaerobic Membrane Bioreactors (AnMBRs) are able to effectively treat DWW at psychrophilic temperatures (10–30 °C), lower temperatures increase methane solubility leading to increased energy losses in the form of dissolved methane in the effluent. Estimates of dissolved methane losses are typically based on concentrations calculated using Henry's Law but advection limitations can lead to supersaturation of methane between 1.34 and 6.9 times equilibrium concentrations and 11–100% of generated methane being lost in the effluent. In well mixed systems such as AnMBRs which use biogas sparging to control membrane fouling, actual concentrations approach equilibrium values. Non-porous membranes have been used to recover up to 92.6% of dissolved methane and well suited for degassing effluents of Upflow Anaerobic Sludge Blanket (UASB) reactors which have considerable solids and organic contents and can cause pore wetting and clogging in microporous membrane modules. Micro

Total solids content drives high solid anaerobic digestion via mass transfer limitation.

PubMed

Abbassi-Guendouz, Amel; Brockmann, Doris; Trably, Eric; Dumas, Claire; Delgenès, Jean-Philippe; Steyer, Jean-Philippe; Escudié, Renaud

2012-05-01

The role of the total solids (TS) content on anaerobic digestion was investigated in batch reactors. A range of TS contents from 10% to 35% was evaluated, four replicates were performed. The total methane production slightly decreased with TS concentrations increasing from 10% to 25% TS. Two behaviors were observed at 30% TS: two replicates had similar performances to that at 25% TS; for the two other replicates, the methane production was inhibited as observed at 35% TS. This difference suggested that 30% TS content corresponded to a threshold of the solids content, above which methanogenesis was strongly inhibited. The Anaerobic Digestion Model No. 1 (ADM1) was used to describe the experimental data. The effects of hydrolysis step and liquid/gas mass transfer were particularly investigated. The simulations showed that mass transfer limitation could explain the low methane production at high TS, and that hydrolysis rate constants slightly decreased with increasing TS. Copyright © 2012 Elsevier Ltd. All rights reserved.

An examination of the treatment of iron-dosed waste activated sludge by anaerobic digestion.

PubMed

Johnson, D K; Carliell-Marquet, C M; Forster, C F

2003-08-01

Anaerobic digestion is an important sludge treatment process enabling stabilisation of the organic fraction of sewage sludge prior to land application. Any practice which might retard the anaerobic digestion process will jeopardize the stability of the resulting digested sludge. This paper reports on an investigation into the relative digestibility of iron-dosed waste activated sludge (WAS) from a sewage treatment works (STW) with chemical phosphorus removal (CPR), in comparison to WAS from a works without phosphorus removal. Two laboratory scale anaerobic digesters (51) were fed initially with non iron-dosed WAS (Works M) at a solids retention time of 19 days. After 2 months the iron-dosed CPR sludge (Works R) was introduced into the second digester, resulting in a 32% decrease in biogas production and an increase in the methane content of the biogas from an average of 74% to 81%. Pre-treatment of the CPR sludge with sodium sulphide and shear, both alone and in combination, caused the gas production to deteriorate further. Pre-acidification and pre-treatment with EDTA did result in an enhanced gas production but it was still not comparable with that of the digester being fed with non-iron-dosed sludge. The daily gas production was found to be linearly related to the amount of bound iron in the sludge.

Low-temperature anaerobic digestion of swine manure in a plug-flow reactor.

PubMed

Massé, Daniel I; Gilbert, Yan; Saady, N M C; Liu, Charle

2013-01-01

A low-temperature (25 degrees C) anaerobic eight-compartment (PF01 to PF08) cascade reactor simulating a plug-flow reactor (PFR) treating pig manure was monitored for a year. The bioreactor was fed at an average loading rate of 2.4 +/- 0.2 g of total chemical oxygen demand (TCOD) per litre of reactor per day for a theoretical hydraulic retention time (HRT) of 67 +/- 7 d. An average of 79% of TCOD was removed from pig manure (converted into biogas and in sediments), whereas specific methane yields ranging from 397 to 482 NL CH4 kg(-1) VS (148.6 to 171.4 NL CH4 kg(-1) TCOD) were obtained. After 150 d, fluctuating performances of the process were observed, associated with solids accumulation in the upstream compartments, preventing the complete anaerobic digestion of swine manure in the compartments PF01 to PF04. Low-temperature anaerobic PFR represents an interesting alternative for the treatment of pig manure and recovery of green energy. Further investigations regarding a modified design, with better accumulating solids management, are needed to optimize the performance of this low-temperature PFR treating pig manure.

High-concentration sugars production from corn stover based on combined pretreatments and fed-batch process.

PubMed

Yang, Maohua; Li, Wangliang; Liu, Binbin; Li, Qiang; Xing, Jianmin

2010-07-01

In this paper, high-concentration sugars were produced from pretreated corn stover. The raw corn stover was pretreated in a process combining steam explosion and alkaline hydrogen-peroxide. The hemicellulose and lignin were removed greatly. The cellulose content increased to 73.2%. Fed-batch enzymatic hydrolysis was initiated with 12% (w/v) solids loading and 20 FPU/g solids. Then, 6% solids were fed consecutively at 12, 36 and 60 h. After 144 h, the final concentrations of reducing sugar, glucose, cellobiose and xylose reached 220, 175, 22 and 20 g/L, respectively. The final total biomass conversion was 60% in fed-batch process. Copyright 2009 Elsevier Ltd. All rights reserved.

Biogas and methane yield in response to co- and separate digestion of biomass wastes.

PubMed

Adelard, Laetitia; Poulsen, Tjalfe G; Rakotoniaina, Volana

2015-01-01

The impact of co-digestion as opposed to separate digestion, on biogas and methane yield (apparent synergetic effects) was investigated for three biomass materials (pig manure, cow manure and food waste) under mesophilic conditions over a 36 day period. In addition to the three biomass materials (digested separately), 13 biomass mixtures (co-digested) were used. Two approaches for modelling biogas and methane yield during co-digestion, based on volatile solids concentration and ultimate gas and methane potentials, were evaluated. The dependency of apparent synergetic effects on digestion time and biomass mixture composition was further assessed using measured cumulative biogas and methane yields and specific biogas and methane generation rates. Results indicated that it is possible, based on known volatile solids concentration and ultimate biogas or methane yields for a set of biomass materials digested separately, to accurately estimate gas yields for biomass mixtures made from these materials using calibrated models. For the biomass materials considered here, modelling indicated that the addition of pig manure is the main cause of synergetic effects. Co-digestion generally resulted in improved ultimate biogas and methane yields compared to separate digestion. Biogas and methane production was furthermore significantly higher early (0-7 days) and to some degree also late (above 20 days) in the digestion process during co-digestion. © The Author(s) 2014.

Methane generation from cattle residue at a dirt feedlot. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lizdas, D.J.; Coe, W.B.; Turk, M.

1980-08-01

In order to investigate the feasibility of producing fuel gas and an energy-intensive refeed product from dirt feedlot residues by anaerobic fermentation, the Department of Energy awarded Hamilton Standard a contract to operate the Hamilton Standard mobile processing unit at the Monfort of Colorado Kuner feedlot. During the test program a stable fermentation was achieved utilizing aged feedlot pen residue after a sufficient adaption period was provided. Methane yields varied considerably as a function of feedstock source; as low as 1.3 cubic feet per pound of volatile solids from the feedlot stockpile, and as high as 3.5 cubic feet frommore » one of the feedlot pens. Average yield from all pens was 2.5 cubic feed of methane per pound of volatile solids processed. The fermentor liquid effluent and dewatered effluent were acceptable to cattle as a feed ingredient and were used to provide one-half the daily supplemental protein for two groups of twenty steers each. Weight gains and feed conversion were nearly the same as for cattle fed the normal ration. Data from the test program were used to evaluate the economics of producing fuel gas at a large dirt feedlot. A preliminary design for a full scale system to produce unscrubbed fuel gas for the Monfort Kuner feedlot was developed, from which capital and operating costs were estimated. The production cost of fuel gas was then established as a function of byproduct credit given to the fermentor residue as a refeed product. With zero credit, gas can be produced at $6.30 per million Btu. When a credit is assigned to the refeed product based on the cost of urea as a protein source, the production cost falls to $2.70 per million Btu. When a credit is assigned to the refeed product based on the cost of cottonseed meal as a protein source, the production cost is -$21, indicating that the system produces a net income from the value of the refeed product.« less

Conversion of MSW (municipal solids waste) to methane in the SOLCON (solids-concentrating) digester

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biljetina, R.; Srivastava, V.J.; Isaacson, H.R.

1988-01-01

The Institute of Gas Technology (IGT) has been operating a 1200- gallon, anaerobic solids-concentrating (SOLCON) digester at the Walt Disney World Resort Complex in Lake Buena Vista, Florida since January of 1984. This digester development work is part of a larger effort, sponsored by the Gas Research Institute (GRI) Southern California Edison, that provides effective community waste treatment and disposal options while recovering a valuable methane resource from these wastes. Excellent conversions to methane have been obtained in the SOLCON digester during 4 years of uninterrupted operation. Data were collected on: (1) Wastes from experimental municipal wastewater treatment applications. Watermore » hyacinths were harvested from secondary wastewater treatment channels and combined with sludge from primary clarifiers to maximize potential methane recoveries in the digester. (2) Wastes from agricultural operations. Sorghum was selected as a candidate because it represents both a potential energy crop, as well as, a waste resource if only portions of the plant are converted after grain production. (3) Wastes from municipal waste collection.« less

Comparison of high-solids to liquid anaerobic co-digestion of food waste and green waste.

PubMed

Chen, Xiang; Yan, Wei; Sheng, Kuichuan; Sanati, Mehri

2014-02-01

Co-digestion of food waste and green waste was conducted with six feedstock mixing ratios to evaluate biogas production. Increasing the food waste percentage in the feedstock resulted in an increased methane yield, while shorter retention time was achieved by increasing the green waste percentage. Food waste/green waste ratio of 40:60 was determined as preferred ratio for optimal biogas production. About 90% of methane yield was obtained after 24.5 days of digestion, with total methane yield of 272.1 mL/g VS. Based the preferred ratio, effect of total solids (TS) content on co-digestion of food waste and green waste was evaluated over a TS range of 5-25%. Results showed that methane yields from high-solids anaerobic digestion (15-20% TS) were higher than the output of liquid anaerobic digestion (5-10% TS), while methanogenesis was inhibited by further increasing the TS content to 25%. The inhibition may be caused by organic overloading and excess ammonia. Copyright © 2013 Elsevier Ltd. All rights reserved.

Retooling the ethanol industry: thermophilic anaerobic digestion of thin stillage for methane production and pollution prevention.

PubMed

Schaefer, Scott H; Sung, Shihwu

2008-02-01

Anaerobic digestion of corn ethanol thin stillage was tested at thermophilic temperature (55 degrees C) with two completely stirred tank reactors. The thin stillage wastestream was organically concentrated with 100 g/L total chemical oxygen demand and 60 g/L volatiles solids and a low pH of approximately 4.0. Steady-state was achieved at 30-, 20-, and 15-day hydraulic retention times (HRTs) and digester failure at a 12-day HRT. Significant reduction of volatile solids was achieved, with a maximum reduction (89.8%) at the 20-day HRT. Methane yield ranged from 0.6 to 0.7 L methane/g volatile solids removed during steady-state operation. Effluent volatile fatty acids below 200 mg/L as acetic acid were achieved at 20- and 30-day HRTs. Ultrasonic pretreatment was used for one digester, although no significant improvement was observed. Ethanol plant natural gas consumption could be reduced 43 to 59% with the methane produced, while saving an estimated $7 to $17 million ($10 million likely) for a facility producing 360 million L ethanol/y.

High-solid anaerobic digestion of corn straw for methane production and pretreatment of bio-briquette.

PubMed

Li, Yeqing; Yan, Fang; Li, Tao; Zhou, Ying; Jiang, Hao; Qian, Mingyu; Xu, Quan

2018-02-01

In this study, an integrated process was developed to produce methane and high-quality bio-briquette (BB) using corn straw (CS) through high-solid anaerobic digestion (HS-AD). CS was anaerobic digested by using a leach bed reactor at four leachate recirculation strategies. After digesting for 28 days, highest methane yield of 179.6 mL/g-VS, which was corresponded to energy production of 5.55 MJ/kg-CS, was obtained at a higher initial recirculation rate of 32 L-leachate per day. Compared with bio-briquette manufactured from raw CS and lignite, the compressive, immersion and falling strength properties of bio-briquette made from AD-treated CS (solid digestate) and lignite were significantly improved. A preferred BB can be obtained with side compressive strength of 863.8 ± 10.8 N and calorific value of 20.21 MJ/kg-BB. The finding of this study indicated that the integrated process could be an alternative way to produce methane and high-quality BB with CS. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Effect of moisture content on anaerobic methanization of municipal solid waste].

PubMed

Qu, Xian; He, Pin-Jing; Shao, Li-Ming; Bouchez, Théodore

2009-03-15

Biogas production, gas and liquid characteristics were investigated for comparing the effect of moisture content on methanization process of MSW with different compositions of food waste and cellulosic waste. Batch reactors were used to study the anaerobic methanization of typical Chinese and French municipal solid waste (MSW) and cellulosic waste with different moisture content, as 35%, field capacity (65%-70%), 80%, and saturated state (> 95%). The results showed that for the typical Chinese and French waste, which contained putrescible waste, the intermediate product, VFA, was diluted by high content of water, which helped to release the VFA inhibition on hydrolysis and methanization. Mass amount of methane was produced only when the moisture content of typical French waste was higher than 80%, while higher content of moisture was needed when the content of putrescible waste was higher in MSW, as > 95% for typical Chinese waste. Meanwhile the methane production rate and the ultimate cumulated methane production were increased when moisture content was leveled up. The ultimate cumulated methane production of the typical French waste with saturated state was 0.6 times higher than that of the waste with moisture content of 80%. For cellulosic waste, high moisture content of cellulosic materials contributed to increase the attachment area of microbes and enzyme on the surface of the materials, which enhance the waste hydrolysis and methanization. When the moisture content of the cellulosic materials increased from field capacity (65%) to saturated state (> 95%), the ultimate cumulated methane production increased for 3.8 times.

Animal health and greenhouse gas intensity: the paradox of periparturient parasitism.

PubMed

Houdijk, J G M; Tolkamp, B J; Rooke, J A; Hutchings, M R

2017-09-01

Here we provide the first known direct measurements of pathogen challenge impacts on greenhouse gas production, yield and intensity. Twin-rearing ewes were ad libitum fed pelleted lucerne from day -32 to 36 (day 0 is parturition), and repeatedly infected with 10,000 Teladorsagia circumcincta infective larvae (n=16), or sham-dosed with water (n=16). A third group of 16 ewes were fed at 80% of uninfected ewes' feed intake during lactation. Methane emissions were measured in respiration chambers (day 30-36) whilst total tract apparent nutrient digestibility around day 28 informed calculated manure methane and nitrous oxide emissions estimates. Periparturient parasitism reduced feed intake (-9%) and litter weight gain (-7%) and doubled maternal body weight loss. Parasitism reduced daily enteric methane production by 10%, did not affect the methane yield per unit of dry matter intake but increased the yield per unit of digestible organic matter intake by 14%. Parasitism did not affect the daily calculated manure methane and nitrous oxide production, but increased the manure methane and nitrous oxide yields per unit of dry matter intake by 16% and 4%, respectively, and per unit of digestible organic matter intake by 46% and 31%, respectively. Accounting for increased lucerne input for delayed weaning and maternal body weight loss compensation, parasitism increased the calculated greenhouse gas intensity per kg of lamb weight gain for enteric methane (+11%), manure methane (+32%) and nitrous oxide (+30%). Supplemented with the global warming potential associated with production of pelleted lucerne, we demonstrated that parasitism increased calculated global warming potential per kg of lamb weight gain by 16%, which was similar to the measured impact of parasitism on the feed conversion ratio. Thus, arising from a pathogen-induced feed efficiency reduction and modified greenhouse gas emissions, we demonstrated that ovine periparturient parasitism increases greenhouse gas intensity. This implies that ewe worm control can not only improve production efficiency but also reduce the environmental footprint of sheep production systems. Copyright © 2017 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

Replacing alfalfa silage with corn silage in dairy cow diets: Effects on enteric methane production, ruminal fermentation, digestion, N balance, and milk production.

PubMed

Hassanat, F; Gervais, R; Julien, C; Massé, D I; Lettat, A; Chouinard, P Y; Petit, H V; Benchaar, C

2013-07-01

The objective of this study was to determine the effects of replacing alfalfa silage (AS) with corn silage (CS) in dairy cow total mixed rations (TMR) on enteric CH4 emissions, ruminal fermentation characteristics, apparent total-tract digestibility, N balance, and milk production. Nine ruminally cannulated lactating cows were used in a replicated 3×3 Latin square design (32-d period) and fed (ad libitum) a TMR [forage:concentrate ratio of 60:40; dry matter (DM) basis], with the forage portion consisting of either alfalfa silage (0% CS; 56.4% AS in the TMR), a 50:50 mixture of both silages (50% CS; 28.2% AS and 28.2% CS in the TMR), or corn silage (100% CS; 56.4% CS in the TMR). Increasing the CS proportion (i.e., at the expense of AS) in the diet was achieved by decreasing the corn grain proportion and increasing that of soybean meal. Intake of DM and milk yield increased quadratically, whereas DM digestibility increased linearly as the proportion of CS increased in the diet. Increasing the dietary CS proportion resulted in changes (i.e., lower ruminal pH and acetate:propionate ratio, reduced fiber digestibility, decreased protozoa numbers, and lower milk fat and higher milk protein contents) typical of those observed when cows are fed high-starch diets. A quadratic response in daily CH4 emissions was observed in response to increasing the proportion of CS in the diet (440, 483, and 434 g/d for 0% CS, 50% CS, and 100% CS, respectively). Methane production adjusted for intake of DM, and gross or digestible energy was unaffected in cows fed the 50% CS diet, but decreased in cows fed the 100% CS diet (i.e., quadratic effect). Increasing the CS proportion in the diet at the expense of AS improved N utilization, as reflected by the decreases in ruminal NH3 concentration and manure N excretion, suggesting low potential NH3 and N2O emissions. Results from this study, suggest that total replacement of AS with CS in dairy cow diets offers a means of decreasing CH4 output and N losses. However, the reduction in fiber degradation and the resulting increase in volatile solids content of the manure may lead to increased CH4 emissions from manure storage. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Biomethanation potential of macroalgae Ulva spp. and Gracilaria spp. and in co-digestion with waste activated sludge.

PubMed

Costa, J C; Gonçalves, P R; Nobre, A; Alves, M M

2012-06-01

Biochemical methane potential of four species of Ulva and Gracilaria genus was assessed in batch assays at mesophilic temperature. The results indicate a higher specific methane production (per volatile solids) for one of the Ulva sp. compared with other macroalgae and for tests running with 2.5% of total solids (196±9 L CH(4) kg(-1)VS). Considering that macroalgae can potentially be a post treatment of municipal wastewater for nutrients removal, co-digestion of macroalgae with waste activated sludge (WAS) was assessed. The co-digestion of macroalgae (15%) with WAS (85%) is feasible at a rate of methane production 26% higher than WAS alone without decreasing the overall biodegradability of the substrate (42-45% methane yield). The use of anoxic marine sediment as inoculum had no positive effect on the methane production in batch assays. The limiting step of the overall anaerobic digestion process was the hydrolysis. Copyright © 2012 Elsevier Ltd. All rights reserved.

Characteristics of the organic fraction of municipal solid waste and methane production: A review.

PubMed

Campuzano, Rosalinda; González-Martínez, Simón

2016-08-01

Anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) is a viable alternative for waste stabilization and energy recovery. Biogas production mainly depends on the type and amount of organic macromolecules. Based on results from different authors analysing OFMSW from different cities, this paper presents the importance of knowing the OFMSW composition to understand how anaerobic digestion can be used to produce methane. This analysis describes and discusses physical, chemical and bromatological characteristics of OFMSW reported by several authors from different countries and cities and their relationship to methane production. The main conclusion is that the differences are country and not city dependant. Cultural habits and OFMSW management systems do not allow a generalisation but the individual analysis for specific cities allow understanding the general characteristics for a better methane production. Not only are the OFMSW characteristics important but also the conditions under which the methane production tests were performed. Copyright © 2016. Published by Elsevier Ltd.

Enhanced Solid-State Biogas Production from Lignocellulosic Biomass by Organosolv Pretreatment

PubMed Central

Mirmohamadsadeghi, Safoora; Zamani, Akram; Horváth, Ilona Sárvári

2014-01-01

Organosolv pretreatment was used to improve solid-state anaerobic digestion (SSAD) for methane production from three different lignocellulosic substrates (hardwood elm, softwood pine, and agricultural waste rice straw). Pretreatments were conducted at 150 and 180°C for 30 and 60 min using 75% ethanol solution as an organic solvent with addition of sulfuric acid as a catalyst. The statistical analyses showed that pretreatment temperature was the significant factor affecting methane production. Optimum temperature was 180°C for elmwood while it was 150°C for both pinewood and rice straw. Maximum methane production was 152.7, 93.7, and 71.4 liter per kg carbohydrates (CH), which showed up to 32, 73, and 84% enhancement for rice straw, elmwood, and pinewood, respectively, compared to those from the untreated substrates. An inverse relationship between the total methane yield and the lignin content of the substrates was observed. Kinetic analysis of the methane production showed that the process followed a first-order model for all untreated and pretreated lignocelluloses. PMID:25243134

Effect of thermal, acid, alkaline and alkaline-peroxide pretreatments on the biochemical methane potential and kinetics of the anaerobic digestion of wheat straw and sugarcane bagasse.

PubMed

Bolado-Rodríguez, Silvia; Toquero, Cristina; Martín-Juárez, Judit; Travaini, Rodolfo; García-Encina, Pedro Antonio

2016-02-01

The effect of thermal, acid, alkaline and alkaline-peroxide pretreatments on the methane produced by the anaerobic digestion of wheat straw (WS) and sugarcane bagasse (SCB) was studied, using whole slurry and solid fraction. All the pretreatments released formic and acetic acids and phenolic compounds, while 5-hydroxymetilfurfural (HMF) and furfural were generated only by acid pretreatment. A remarkable inhibition was found in most of the whole slurry experiments, except in thermal pretreatment which improved methane production compared to the raw materials (29% for WS and 11% for SCB). The alkaline pretreatment increased biodegradability (around 30%) and methane production rate of the solid fraction of both pretreated substrates. Methane production results were fitted using first order or modified Gompertz equations, or a novel model combining both equations. The model parameters provided information about substrate availability, controlling step and inhibitory effect of compounds generated by each pretreatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Liquid Oxygen/Liquid Methane Propulsion and Cryogenic Advanced Development

NASA Technical Reports Server (NTRS)

Klem, Mark D.; Smith, Timothy D.; Wadel, Mary F.; Meyer, Michael L.; Free, James M.; Cikanek, Harry A., III

2011-01-01

Exploration Systems Architecture Study conducted by NASA in 2005 identified the liquid oxygen (LOx)/liquid methane (LCH4) propellant combination as a prime candidate for the Crew Exploration Vehicle Service Module propulsion and for later use for ascent stage propulsion of the lunar lander. Both the Crew Exploration Vehicle and Lunar Lander were part the Constellation architecture, which had the objective to provide global sustained lunar human exploration capability. From late 2005 through the end of 2010, NASA and industry matured advanced development designs for many components that could be employed in relatively high thrust, high delta velocity, pressure fed propulsion systems for these two applications. The major investments were in main engines, reaction control engines, and the devices needed for cryogenic fluid management such as screens, propellant management devices, thermodynamic vents, and mass gauges. Engine and thruster developments also included advanced high reliability low mass igniters. Extensive tests were successfully conducted for all of these elements. For the thrusters and engines, testing included sea level and altitude conditions. This advanced development provides a mature technology base for future liquid oxygen/liquid methane pressure fed space propulsion systems. This paper documents the design and test efforts along with resulting hardware and test results.

Assessment of microbial viability in municipal sludge following ultrasound and microwave pretreatments and resulting impacts on the efficiency of anaerobic sludge digestion.

PubMed

Cella, Monica Angela; Akgul, Deniz; Eskicioglu, Cigdem

2016-03-01

A range of ultrasonication (US) and microwave irradiation (MW) sludge pretreatments were compared to determine the extent of cellular destruction in micro-organisms within secondary sludge and how this cellular destruction translated to anaerobic digestion (AD). Cellular lysis/inactivation was measured using two microbial viability assays, (1) Syto 16® Green and Sytox® Orange counter-assay to discern the integrity of cellular membranes and (2) a fluorescein diacetate assay to understand relative enzymatic activity. A range of MW intensities (2.17-6.48 kJ/g total solids or TS, coinciding temperatures of 60-160 °C) were selected for comparison via viability assays; a range of corresponding US intensities (2.37-27.71 kJ/g TS, coinciding sonication times of 10-60 min at different amplitudes) were also compared to this MW range. The MW pretreatment of thickened waste activated sludge (tWAS) caused fourfold to fivefold greater cell death than non-pretreated and US-pretreated tWAS. The greatest microbial destruction occurred at MW intensities greater than 2.62 kJ/g TS of sludge, after which increased energy input via MW did not appear to cause greater microbial death. In addition, the optimal MW pretreatment (80 °C, 2.62 kJ/g TS) and corresponding US pretreatment (10 min, 60 % amplitude, 2.37 kJ/g TS) were administered to the tWAS of a mixed sludge and fed to anaerobic digesters over sludge retention times (SRTs) of 20, 14, and 7 days to compare effects of feed pretreatment on AD efficiency. The digester utilizing MW-pretreated tWAS (80 °C, 2.62 kJ/g TS) had the greatest fecal coliform removal (73.4 and 69.8 % reduction, respectively), greatest solids removal (44.2 % TS reduction), and highest overall methane production (248.2 L CH4/kg volatile solids) at 14- and 7-day SRTs. However, despite the fourfold to fivefold increases in cell death upon pretreatment, improvements from the digester fed MW-pretreated sludge were marginal (i.e., increases in efficiency of less than 3-10 %) and likely due to a smaller proportion of cells (10-20 %) in the polymeric network and mixed sludge fed to digesters.

Effects of dietary methyl sulfonyl methane (MSM) supplementation on growth performance, nutrient digestibility, meat quality, excreta microbiota, excreta gas emission, and blood profiles in broilers.

PubMed

Jiao, Y; Park, J H; Kim, Y M; Kim, I H

2017-07-01

A 29-d trial was conducted to evaluate the effects of dietary methyl sulfonyl methane (MSM) supplementation on growth performance, meat quality, nutrient digestibility, excreta microbiota, excreta gas emission, and blood profiles in broilers. A total of 816 1-day-old male Ross 308 broilers (44 ± 0.44 g) were assigned to 4 dietary treatments, composed of 12 replicates with 17 birds per replicate. The 4 treatments were: 1) CON, basal diet; 2) S1, CON + 0.05% MSM; 3) S2, CON + 0.10% MSM; 4) S3, CON + 0.20% MSM. In the current study, body weight (BW) on d 14 and 29 showed significant improvement as dietary MSM increased from 0.05% to 0.20% (P < 0.05). During d 1 to 14 and overall, higher (P < 0.05) body weight gain (BWG) and lower feed conversion ratio (FCR) were observed in broilers fed MSM diets. Between d 15 and 29, higher (P < 0.05) BWG was observed in broilers fed MSM diets. Redness (a*) was increased linearly (P < 0.05) in broilers fed MSM diets. On d 3, 5, and 7, drip loss was decreased linearly (P < 0.05) in broilers fed MSM diets. Lactobacillus and E. coli were effected linearly (P < 0.05) in broilers fed MSM diets. Alanine aminotransferase (ALT), white blood cells (WBC) and lymphocytes were improved linearly (P < 0.05) in broilers fed MSM diets. In conclusion, dietary supplementation MSM has positive effects on growth performance, meat quality, excreta microbiota, and blood profiles in broilers. © 2017 Poultry Science Association Inc.

Fumaric Acid Production from Alkali-Pretreated Corncob by Fed-Batch Simultaneous Saccharification and Fermentation Combined with Separated Hydrolysis and Fermentation at High Solids Loading.

PubMed

Li, Xin; Zhou, Jin; Ouyang, Shuiping; Ouyang, Jia; Yong, Qiang

2017-02-01

Production of fumaric acid from alkali-pretreated corncob (APC) at high solids loading was investigated using a combination of separated hydrolysis and fermentation (SHF) and fed-batch simultaneous saccharification and fermentation (SSF) by Rhizopus oryzae. Four different fermentation modes were tested to maximize fumaric acid concentration at high solids loading. The highest concentration of 41.32 g/L fumaric acid was obtained from 20 % (w/v) APC at 38 °C in the combined SHF and fed-batch SSF process, compared with 19.13 g/L fumaric acid in batch SSF alone. The results indicated that a combination of SHF and fed-batch SSF significantly improved production of fumaric acid from lignocellulose by R. oryzae than that achieved with batch SSF at high solids loading.

A start-up of psychrophilic anaerobic sequence batch reactor digesting a 35 % total solids feed of dairy manure and wheat straw.

PubMed

Saady, Noori M Cata; Massé, Daniel I

2015-12-01

Zero liquid discharge is currently an objective in livestock manure management to minimize water pollution. This paper reports the start-up phase of a novel psychrophilic (20 °C) dry anaerobic digestion of dairy manure with bedding fed at 35 % total solids and an organic loading rate of 3.0 g total chemical oxygen demand kg(-1) inoculum day(-1) in anaerobic sequence batch reactors. The specific methane (CH4) yield ranged from 165.4 ± 9.8 to 213.9 ± 13.6 NL CH4 kg(-1) volatile solids (VS) with an overall average of 188 ± 17 NL CH4 kg(-1) VS during 11 successive start-up cycles (231 days) and a maximum CH4 production rate of 10.2 ± 0.6 NL CH4 kg(-1) VS day(-1). The inoculum-to-substrate (VS-based) ratio ranged from 4.06 to 4.47. Although methanogenesis proceeded fairly well the hydrolysis seemed to be the rate limiting step. It is possible start up psychrophilic dry anaerobic digestion of cow feces and wheat straw at feed TS of 35 % within 7-10 successive cycles (147-210 days).

Transport Mechanism of Guest Methane in Water-Filled Nanopores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bui, Tai; Phan, Anh; Cole, David R.

We computed the transport of methane through 1 nm wide slit-shaped pores carved out of selected solid substrates using classical molecular dynamics simulations. The transport mechanism was elucidated via the implementation of the well-tempered metadynamics algorithm, which allowed for the quantification and visualization of the free energy landscape sampled by the guest molecule. Models for silica, magnesium oxide, alumina, muscovite, and calcite were used as solid substrates. Slit-shaped pores of width 1 nm were carved out of these materials and filled with liquid water. Methane was then inserted at low concentration. The results show that the diffusion of methane throughmore » the hydrated pores is strongly dependent on the solid substrate. While methane molecules diffuse isotropically along the directions parallel to the pore surfaces in most of the pores considered, anisotropic diffusion was observed in the hydrated calcite pore. The differences observed in the various pores are due to local molecular properties of confined water, including molecular structure and solvation free energy. The transport mechanism and the diffusion coefficients are dependent on the free energy barriers encountered by one methane molecule as it migrates from one preferential adsorption site to a neighboring one. It was found that the heterogeneous water distribution in different hydration layers and the low free energy pathways in the plane parallel to the pore surfaces yield the anisotropic diffusion of methane molecules in the hydrated calcite pore. Our observations contribute to an ongoing debate on the relation between local free energy profiles and diffusion coefficients and could have important practical consequences in various applications, ranging from the design of selective membranes for gas separations to the sustainable deployment of shale gas.« less

Transport Mechanism of Guest Methane in Water-Filled Nanopores

DOE PAGES

Bui, Tai; Phan, Anh; Cole, David R.; ...

2017-05-11

We computed the transport of methane through 1 nm wide slit-shaped pores carved out of selected solid substrates using classical molecular dynamics simulations. The transport mechanism was elucidated via the implementation of the well-tempered metadynamics algorithm, which allowed for the quantification and visualization of the free energy landscape sampled by the guest molecule. Models for silica, magnesium oxide, alumina, muscovite, and calcite were used as solid substrates. Slit-shaped pores of width 1 nm were carved out of these materials and filled with liquid water. Methane was then inserted at low concentration. The results show that the diffusion of methane throughmore » the hydrated pores is strongly dependent on the solid substrate. While methane molecules diffuse isotropically along the directions parallel to the pore surfaces in most of the pores considered, anisotropic diffusion was observed in the hydrated calcite pore. The differences observed in the various pores are due to local molecular properties of confined water, including molecular structure and solvation free energy. The transport mechanism and the diffusion coefficients are dependent on the free energy barriers encountered by one methane molecule as it migrates from one preferential adsorption site to a neighboring one. It was found that the heterogeneous water distribution in different hydration layers and the low free energy pathways in the plane parallel to the pore surfaces yield the anisotropic diffusion of methane molecules in the hydrated calcite pore. Our observations contribute to an ongoing debate on the relation between local free energy profiles and diffusion coefficients and could have important practical consequences in various applications, ranging from the design of selective membranes for gas separations to the sustainable deployment of shale gas.« less

Treatment and Energy Valorisation of an Agro-Industrial Effluent in Upflow Anaerobic Sludge Reactor (UASB)

NASA Astrophysics Data System (ADS)

Martins, Ramiro; Boaventura, Rui; Paulista, Larissa

2017-12-01

The accelerated growth of the population brings with it an increase in the generation of agro-industrial effluents. The inadequate discharge of these effluents significantly affects the quality of water resources. In this way, it becomes important to invest in treatment processes for agro-industrial effluents, particularly low-cost ones. In this context, the present study includes the design and construction of an UASB reactor and optimization of the anaerobic digestion treatment of the raw effluent from sweet chestnut production in the agro-industrial company Sortegel. The efficiency of the system was evaluated through the determination / monitoring of oxygen chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total suspended solids (TSS), biogas production rate and quality (% methane). The reactor was fed for 25 weeks and operated under mesophilic conditions (temperature 30-40 °C). Different values were tested for the hydraulic retention time (HRT) and volumetric flow rate (VF): 0.66 days (VF=1509 L.m-3.d-1); 1.33 days (VF=755 L.m-3.d-1); 2.41 d days (VF=415 L.m-3.d-1). The average COD removal efficiency reached values of 69%, 82% and 75%, respectively, and simultaneously the associated BOD5 removal efficiency was 84%, 91% and 70%. As regards TSS, removal values were 78%, 94% and 63%. In addition, high methane production rates were obtained, between 2500 and 4800 L CH4.kg-1 COD removed d-1. For all the hydraulic retention times tested, high concentrations of methane in the biogas were recorded: 66-75%, 70% and 75% for HRT of 0.66, 1.33 and 2.41 days, respectively.

[Agroindustrial wastes methanization and bacterial composition in anaerobic digestion].

PubMed

González-Sánchez, María E; Pérez-Fabiel, Sergio; Wong-Villarreal, Arnoldo; Bello-Mendoza, Ricardo; Yañez-Ocampo, Gustavo

2015-01-01

The tons of organic waste that are annually generated by agro-industry, can be used as raw material for methane production. For this reason, it is important to previously perform biodegradability tests to organic wastes for their full scale methanization. This paper addresses biodegradability, methane production and the behavior of populations of eubacteria and archaeabacteria during anaerobic digestion of banana, mango and papaya agroindustrial wastes. Mango and banana wastes had higher organic matter content than papaya in terms of their volatile solids and total solid rate (94 and 75% respectively). After 63 days of treatment, the highest methane production was observed in banana waste anaerobic digestion: 63.89ml CH4/per gram of chemical oxygen demand of the waste. In the PCR-DGGE molecular analysis, different genomic footprints with oligonucleotides for eubacteria and archeobacteria were found. Biochemical methane potential results proved that banana wastes have the best potential to be used as raw material for methane production. The result of a PCR- DGGE analysis using specific oligonucleotides enabled to identify the behavior of populations of eubacteria and archaeabacteria present during the anaerobic digestion of agroindustrial wastes throughout the process. Copyright © 2015 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Dynamics of protozoa in the rumen of cattle.

PubMed

Ffoulkes, D; Leng, R A

1988-05-01

1. The dynamics of protozoa were studied in two groups of rumen-fistulated cattle fed on a basal diet of molasses ad lib., with oaten chaff given at 6 or 18 g/kg live weight. This diet resulted in different mixtures of protozoal species in the populations in the rumen. 2. The rumen protozoa were studied by intrarumen injections of protozoa labelled in vitro with [14CH3]choline. An indication of protozoal death and fermentation of protozoal cell residues was obtained by measuring 14C loss via the methane pool. 3. After a single injection of labelled protozoa, the decline in the specific radioactivity (microCi/g nitrogen) of the protozoal pool in the rumen indicated that first-order kinetic processes applied. Conversely the specific radioactivity of protozoa, incubated in rumen fluid, remained constant indicating no growth in vitro, presumably owing to a rapid exhaustion of essential nutrients. 4. The protozoal populations in the rumen of cattle fed on the diet with the low level of oaten chaff were mainly small ciliates; but on the higher level of chaff in the diet, the large ciliates were a higher proportion of the total protozoal population present. 5. The mean pool size of protozoa in the rumen was significantly larger and the protozoal half-life tended to be longer for cattle fed on the higher level of chaff in the diet. The apparent production rate of protozoa in cattle fed on each diet was not significantly different and there were no differences in the production rate of methane. The percentage losses of label from protozoa in the rumen via the methane pool were not significantly different on the two diets and indicated that 74% of the protozoa that were apparently irreversibly lost from the rumen could be accounted for by death and lysis in the rumen and therefore only 26% of protozoa apparently entered the lower digestive tract.

Feeding of tropical trees and shrub foliages as a strategy to reduce ruminal methanogenesis: studies conducted in Cuba.

PubMed

Delgado, Denia Caridad; Galindo, Juana; González, Rogelio; González, Niurca; Scull, Idania; Dihigo, Luís; Cairo, Juan; Aldama, Ana Irma; Moreira, Onidia

2012-06-01

The aim of this paper was to present the main results obtained in Cuba on the effects of feeding tropical trees and shrubs on rumen methanogenesis in animals fed with low quality fibrous diets. More than 20 tree and shrub foliages were screened for phytochemicals and analyzed for chemical constituents. From these samples, seven promising plants (Samanea saman, Albizia lebbeck, Tithonia diversifolia, Leucaena leucocephala, Trichantera gigantea, Sapindus saponaria, and Morus alba) were evaluated for methane reduction using an in vitro rumen fermentation system. Results indicated that the inclusion levels of 25% of Sapindo, Morus, or Trichantera foliages in the foliages/grass mixtures (grass being Pennisetum purpureum) reduced (P < 0.01) methane production in vitro when compared to Pennisetum alone (17.0, 19.1, and 18.0 versus 26.2 mL CH(4)/g fermented dry matter, respectively). It was demonstrated that S. saman, A. lebbeck, or T. diversifolia accession 23 foliages when mixed at the rate of 30% in Cynodon nlemfuensis grass produced lower methane compared to the grass alone. Inclusion levels of 15% and 25% of a ruminal activator supplement containing 29% of L. leucocehala foliage meal reduced methane by 37% and 42% when compared to the treatment without supplementation. In vivo experiment with sheep showed that inclusion of 27% of L. leucocephala in the diet increased the DM intake but did not show significant difference in methane production compared to control diet without this foliage. The results of these experiments suggest that the feeding of tropical tree and shrub foliages could be an attractive strategy for reduction of ruminal methanogenesis from animals fed with low-quality forage diets and for improving their productivity.

Effect of the anode feeding composition on the performance of a continuous-flow methane-producing microbial electrolysis cell.

PubMed

Zeppilli, Marco; Villano, Marianna; Aulenta, Federico; Lampis, Silvia; Vallini, Giovanni; Majone, Mauro

2015-05-01

A methane-producing microbial electrolysis cell (MEC) was continuously fed at the anode with a synthetic solution of soluble organic compounds simulating the composition of the soluble fraction of a municipal wastewater. The MEC performance was assessed at different anode potentials in terms of chemical oxygen demand (COD) removal efficiency, methane production, and energy efficiency. As a main result, about 72-80% of the removed substrate was converted into current at the anode, and about 84-86% of the current was converted into methane at the cathode. Moreover, even though both COD removed and methane production slightly decreased as the applied anode potential decreased, the energy efficiency (i.e., the energy recovered as methane with respect to the energy input into the system) increased from 54 to 63%. Denaturing gradient gel electrophoresis (DGGE) analyses revealed a high diversity in the anodic bacterial community with the presence of both fermentative (Proteiniphilum acetatigenes and Petrimonas sulphurifila) and aerobic (Rhodococcus qingshengii) microorganisms, whereas only two microorganisms (Methanobrevibacter arboriphilus and Methanosarcina mazei), both assignable to methanogens, were observed in the cathodic community.

Increase of methane formation by ethanol addition during continuous fermentation of biogas sludge.

PubMed

Refai, Sarah; Wassmann, Kati; van Helmont, Sebastian; Berger, Stefanie; Deppenmeier, Uwe

2014-12-01

Very recently, it was shown that the addition of acetate or ethanol led to enhanced biogas formation rates during an observation period of 24 h. To determine if increased methane production rates due to ethanol addition can be maintained over longer time periods, continuous reactors filled with biogas sludge were developed which were fed with the same substrates as the full-scale reactor from which the sludge was derived. These reactors are well reflected conditions of a full-scale biogas plant during a period of 14 days. When the fermenters were pulsed with 50-100 mM ethanol, biomethanation increased by 50-150 %, depending on the composition of the biogas sludge. It was also possible to increase methane formation significantly when 10-20 mM pure ethanol or ethanolic solutions (e.g. beer) were added daily. In summary, the experiments revealed that "normal" methane production continued to take place, but ethanol led to production of additional methane.

Design and operation of an anaerobic digester for waste management and fuel generation during long term lunar mission

NASA Astrophysics Data System (ADS)

Dhoble, Abhishek S.; Pullammanappallil, Pratap C.

2014-10-01

Waste treatment and management for manned long term exploratory missions to moon will be a challenge due to longer mission duration. The present study investigated appropriate digester technologies that could be used on the base. The effect of stirring, operation temperature, organic loading rate and reactor design on the methane production rate and methane yield was studied. For the same duration of digestion, the unmixed digester produced 20-50% more methane than mixed system. Two-stage design which separated the soluble components from the solids and treated them separately had more rapid kinetics than one stage system, producing the target methane potential in one-half the retention time than the one stage system. The two stage system degraded 6% more solids than the single stage system. The two stage design formed the basis of a prototype digester sized for a four-person crew during one year exploratory lunar mission.

Renewable Biochemical Methane Potential through Anaerobic Co-digestion from Selective Feed Stocks

NASA Astrophysics Data System (ADS)

Thara, K.; Navis Karthika, Ignatius; Dheenadayalan, M. S., Dr

2017-08-01

Biochemical Methane Potential (BMP) analysis provides a measure of the anaerobic biodegradability of a given substrate. BMP test is also used to evaluate the potential biogas (methane) production between various Co-digestion substrates. This test is also used to determine the amount of organic carbon in a given material that can be an aerobically converted to methane-Biogas. Studies were carried out for the production of biogas from the leather solid waste. Co-digestion (simultaneous digestion of two or more substrates) studies were carried out in batch reactor using the fleshing (a solid waste generated during the processing of raw hides or skins into finished leather) along with the fruit and vegetable waste at mesophilic condition 35° C). The anaerobic methanogenic seed sludge prepared separately followed by standard BMP test, which was used as the seed inoculums. Recent research on this topic is reviewed in this current paper.

Effects of rutin and buckwheat seeds on energy metabolism and methane production in dairy cows.

PubMed

Stoldt, Ann-Kathrin; Derno, Michael; Das, Gürbüz; Weitzel, Joachim M; Wolffram, Siegfried; Metges, Cornelia C

2016-03-01

Flavonoids are secondary plant metabolites with several health promoting effects. As dairy cows often suffer from metabolic imbalance and health problems, interest is growing in health improvements by plant substances such as flavonoids. Our group has recently shown that the flavonoids quercetin and rutin (a glucorhamnoside of quercetin) are bioavailable in cows when given via a duodenal fistula or orally, respectively, affect glucose metabolism, and have beneficial effects on liver health. Furthermore, flavonoids may reduce rumen methane production in vitro through their antibacterial properties. To test the hypothesis that rutin has effects on energy metabolism, methane production, and production performance in dairy cows, we fed rutin trihydrate at a dose of 100mg/kg of body weight to a group of 7 lactating dairy cows for 2 wk in a crossover design. In a second experiment, 2 cows were fed the same ration but were supplemented with buckwheat seeds (Fagopyrum tartaricum), providing rutin at a dose comparable to the first experiment. Two other cows receiving barley supplements were used as controls in a change-over mode. Blood samples were taken weekly and respiration measurements were performed at the end of each treatment. Supplementation of pure rutin, but not of rutin contained in buckwheat seeds, increased the plasma quercetin content. Methane production and milk yield and composition were not affected by rutin treatment in either form. Plasma glucose, β-hydroxybutyrate, and albumin were increased by pure rutin treatment, indicating a possible metabolic effect of rutin on energy metabolism of dairy cows. In addition, we did not show that in vivo ruminal methane production was reduced by rutin. In conclusion, we could not confirm earlier reports on in vitro methane reduction by rutin supplementation in dairy cows in established lactation. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

An efficient method to improve the production of methane from anaerobic digestion of waste activated sludge.

PubMed

Li, Xiaolan; Xu, Xueqin; Huang, Shansong; Zhou, Yun; Jia, Haijiang

2017-10-01

Methane production from waste activated sludge (WAS) anaerobic digestion is always low due to slow hydrolysis rate and inappropriate ratio of carbon to nitrogen (C/N). In this work, a novel approach, i.e., co-digestion of WAS and tobacco waste (TW) using ozone pretreatment, to greatly enhance the production of methane is reported. Experimental results showed the optimal C/N and ozone dosage for methane production was 24:1 and 90 mg/g suspended solids, and the corresponding methane production was 203.6 mL/g volatile suspended solids, which was 1.3-fold that in mono-WAS digestion. Further investigation showed the co-digestion of WAS and TW was beneficial to the consumptions of protein and cellulose; also, the presence of ozone enhanced the disruption of organic substrates and production of short chain fatty acids, which provided sufficient digestion substrates for methane generation. Analysis of microbial community structure suggested that members of the phyla Bacteroidetes and Firmicutes were the dominant species when ozone pretreatment was applied. The findings obtained in this work might be of great importance for the treatment of WAS and TW.

Biochemical methane potential tests of different autoclaved and microwaved lignocellulosic organic fractions of municipal solid waste.

PubMed

Pecorini, Isabella; Baldi, Francesco; Carnevale, Ennio Antonio; Corti, Andrea

2016-10-01

The aim of this research was to enhance the anaerobic biodegradability and methane production of two synthetic Organic Fractions of Municipal Solid Waste with different lignocellulosic contents by assessing microwave and autoclave pre-treatments. Biochemical Methane Potential assays were performed for 21days. Changes in the soluble fractions of the organic matter (measured by soluble chemical oxygen demand, carbohydrates and proteins), the first order hydrolysis constant kh and the cumulated methane production at 21days were used to evaluate the efficiency of microwaving and autoclaving pretreatments on substrates solubilization and anaerobic digestion. Microwave treatment led to a methane production increase of 8.5% for both the tested organic fractions while autoclave treatment had an increase ranging from 1.0% to 4.4%. Results showed an increase of the soluble fraction after pre-treatments for both the synthetic organic fractions. Soluble chemical oxygen demand observed significant increases for pretreated substrates (up to 219.8%). In this regard, the mediocre results of methane's production led to the conclusion that autoclaving and microwaving resulted in the hydrolysis of a significant fraction of non-biodegradable organic substances recalcitrant to anaerobic digestion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimization of solid content, carbon/nitrogen ratio and food/inoculum ratio for biogas production from food waste.

PubMed

Dadaser-Celik, Filiz; Azgin, Sukru Taner; Yildiz, Yalcin Sevki

2016-12-01

Biogas production from food waste has been used as an efficient waste treatment option for years. The methane yields from decomposition of waste are, however, highly variable under different operating conditions. In this study, a statistical experimental design method (Taguchi OA 9 ) was implemented to investigate the effects of simultaneous variations of three parameters on methane production. The parameters investigated were solid content (SC), carbon/nitrogen ratio (C/N) and food/inoculum ratio (F/I). Two sets of experiments were conducted with nine anaerobic reactors operating under different conditions. Optimum conditions were determined using statistical analysis, such as analysis of variance (ANOVA). A confirmation experiment was carried out at optimum conditions to investigate the validity of the results. Statistical analysis showed that SC was the most important parameter for methane production with a 45% contribution, followed by F/I ratio with a 35% contribution. The optimum methane yield of 151 l kg -1 volatile solids (VS) was achieved after 24 days of digestion when SC was 4%, C/N was 28 and F/I were 0.3. The confirmation experiment provided a methane yield of 167 l kg -1 VS after 24 days. The analysis showed biogas production from food waste may be increased by optimization of operating conditions. © The Author(s) 2016.

Influence of solid-liquid separation strategy on biogas yield from a stratified swine production system.

PubMed

Cestonaro do Amaral, André; Kunz, Airton; Radis Steinmetz, Ricardo Luis; Scussiato, Lucas Antunes; Tápparo, Deisi Cristina; Gaspareto, Taís Carla

2016-03-01

As the fourth largest swine producer and exporter, Brazil has increased its participation in the global swine production market. Generally, these units concentrate a large number of animals and generate effluents that must be correctly managed to prevent environmental impacts, being anaerobic digestion is an interesting alternative for treating these effluents. The low-volatile solid concentration in the manure suggests the need for solid-liquid separation as a tool to improve the biogas generation capacity. This study aimed to determine the influence of simplified and inexpensive solid-liquid separation strategies (screening and settling) and the different manures produced during each swine production phase (gestating and farrowing sow houses, nursery houses and finishing houses) on biogas and methane yield. We collected samples in two gestating sow houses (GSH-a and GSH-b), two farrowing sow houses (FSH-a and FSH-b), a nursery house (NH) and a finishing house (FH). Biochemical methane potential (BMP) tests were performed according to international standard procedures. The settled sludge fraction comprised 20-30% of the raw manure volume, which comprises 40-60% of the total methane yield. The methane potential of the settled sludge fraction was approximately two times higher than the methane potential of the supernatant fraction. The biogas yield differed among the raw manures from different swine production phases (GSH-a 326.4 and GSH-b 577.1; FSH-a 860.1 and FSH-b 479.2; NH -970.2; FH 474.5 NmLbiogas.gVS(-1)). The differences were relative to the production phase (feed type and feeding techniques) and the management of the effluent inside the facilities (water management). Brazilian swine production has increased his participation in the global market, been the fourth producer and the fourth exporter. The segregation of swine production in multiple sites has increased its importance, due to the possibilities to have more specialized units. Generally, these units concentrate a large number of animals and generate effluents that must be correctly managed to avoid environmental impact. Due to the biodegradability of manure, anaerobic digestion is an interesting alternative to treat these effluents. The low volatile solid concentration in the swine manure suggests the need for solid-liquid separation as a tool to improve biogas generation capacity. The present study aimed to determine the influence of simplified and cheap solid-liquid separation strategies (based on screening and settling) and different manure of each swine production phases (gestating and farrowing sows houses, nursery houses and finishing houses) on biogas and methane yield. We collected samples in two gestating sows house (GSH-a and GSH-b), two farrowing sows house (FSH-a and FSH-b), a nursery house (NH) and a finishing house (FH). The Biochemical Methane Production (BMP) tests were performed according to international standard procedure (VDI 4630). The settled sludge fraction responds for 20-30% of raw manure volume, producing 40-60% of the total methane yield. The methane potential of settled sludge fraction was about 2 times higher than the supernatant fraction. There are differences on biogas yield between the raw manure of different swine production phases (GSH-a 326.4 and GSH-b 577.1; FSH-a 860.1 and FSH-b 479.2; NH 970.2; FH 474.5 NmLbiogas.gVS(-1)). The differences are relative to production phase (feed type, feeding techniques, etc.), but also the management of the effluent inside the facilities (water management). Copyright © 2015 Elsevier Ltd. All rights reserved.

Modelling the Effect of Diet Composition on Enteric Methane Emissions across Sheep, Beef Cattle and Dairy Cows

PubMed Central

Bell, Matt; Eckard, Richard; Moate, Peter J.; Yan, Tianhai

2016-01-01

Simple Summary Enteric methane emissions produced by ruminant livestock has gained global interest due to methane being a potent greenhouse gas and ruminants being a significant source of emissions. In the absence of measurements, prediction models can facilitate the estimation of enteric methane emissions from ruminant livestock and aid investigation of mitigation options. This study developed a practical method using feed analysis information for predicting enteric methane emissions from sheep, beef cattle and dairy cows fed diets encompassing a wide range of nutrient concentrations. Abstract Enteric methane (CH4) is a by-product from fermentation of feed consumed by ruminants, which represents a nutritional loss and is also considered a contributor to climate change. The aim of this research was to use individual animal data from 17 published experiments that included sheep (n = 288), beef cattle (n = 71) and dairy cows (n = 284) to develop an empirical model to describe enteric CH4 emissions from both cattle and sheep, and then evaluate the model alongside equations from the literature. Data were obtained from studies in the United Kingdom (UK) and Australia, which measured enteric CH4 emissions from individual animals in calorimeters. Animals were either fed solely forage or a mixed ration of forage with a compound feed. The feed intake of sheep was restricted to a maintenance amount of 875 g of DM per day (maintenance level), whereas beef cattle and dairy cows were fed to meet their metabolizable energy (ME) requirement (i.e., production level). A linear mixed model approach was used to develop a multiple linear regression model to predict an individual animal’s CH4 yield (g CH4/kg dry matter intake) from the composition of its diet. The diet components that had significant effects on CH4 yield were digestible organic matter (DOMD), ether extract (EE) (both g/kg DM) and feeding level above maintenance intake: CH4 (g/kg DM intake) = 0.046 (±0.001) × DOMD − 0.113 (±0.023) × EE − 2.47 (±0.29) × (feeding level − 1), with concordance correlation coefficient (CCC) = 0.655 and RMSPE = 14.0%. The predictive ability of the model developed was as reliable as other models assessed from the literature. These components can be used to predict effects of diet composition on enteric CH4 yield from sheep, beef and dairy cattle from feed analysis information. PMID:27618107

Application of methane fermentation technology into organic wastes in closed agricultural system

NASA Astrophysics Data System (ADS)

Endo, Ryosuke; Kitaya, Yoshiaki

Sustainable and recycling-based systems are required in space agriculture which takes place in an enclosed environment. Methane fermentation is one of the most major biomass conversion technologies, because (1) it provides a renewable energy source as biogas including methane, suitable for energy production, (2) the nutrient-rich solids left after digestion can be used as compost for agriculture. In this study, the effect of the application of methane fermentation technology into space agriculture on the material and energy cycle was investigated.

Effect of temperature on continuous dry fermentation of swine manure.

PubMed

Deng, Liangwei; Chen, Chuang; Zheng, Dan; Yang, Hongnan; Liu, Yi; Chen, Ziai

2016-07-15

Laboratory-scale experiments were performed on the dry digestion of solid swine manure in a semi-continuous mode using 4.5 L down plug-flow anaerobic reactors with an organic loading rate of 3.46 kg volatile solids (VS) m(-3) d(-1) to evaluate the effects of temperature (15, 25 and 35 °C). At 15 °C, biogas production was the poorest due to organic overload and acidification, with a methane yield of 0.036 L CH4 g(-1) VS added and a volumetric methane production rate of 0.125 L CH4 L(-1) d(-1). The methane yield and volumetric methane production rate at 25 °C (0.226 L CH4 g(-1) VS added and 0.783 L CH4 L(-1) d(-1), respectively) were 6.24 times higher than those at 15 °C. However, the methane yield (0.237 L CH4 g(-1) VS added) and the volumetric methane production rate (0.821 L CH4 L(-1) d(-1)) at 35 °C were only 4.86% higher than those at 25 °C, which indicated similar results were obtained at 25 °C and 35 °C. The lower biogas production at 35 °C in dry digestion compared with that in wet digestion could be attributed to ammonia inhibition. For a single pig farm, digestion of solid manure is accomplished in small-scale domestic or small-farm bioreactors, for which operating temperatures of 35 °C are sometimes difficult to achieve. Considering biogas production, ammonia inhibition and net energy recovery, an optimum temperature for dry digestion of solid swine manure is 25 °C. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamic effect of leachate recirculation on batch mode solid state anaerobic digestion: Influence of recirculated volume, leachate to substrate ratio and recirculation periodicity.

PubMed

Degueurce, Axelle; Trémier, Anne; Peu, Pascal

2016-09-01

Performances of batch mode solid state anaerobic digestion (SSAD) were investigated through several leachate recirculation strategies. Three parameters were shown to particularly influence methane production rates (MPR) and methane yields: the length of the interval between two recirculation events, the leachate to substrate (L:S) ratio and the volume of leachate recirculated. A central composite factor design was used to determine the influence of each parameter on methane production. Results showed that lengthening the interval between two recirculation events reduced methane yield. This effect can be counteracted by recirculating a large volume of leachate at a low L:S ratio. Steady methane production can be obtained by recirculating small amounts of leachate, and by lengthening the interval between two recirculations, regardless of the L:S ratio. However, several combinations of these parameters led to similar performances meaning that leachate recirculation practices can be modified as required by the specific constraints SSAD plants configurations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems.

PubMed

Shin, Kyuchul; Kumar, Rajnish; Udachin, Konstantin A; Alavi, Saman; Ripmeester, John A

2012-09-11

There is interest in the role of ammonia on Saturn's moons Titan and Enceladus as the presence of water, methane, and ammonia under temperature and pressure conditions of the surface and interior make these moons rich environments for the study of phases formed by these materials. Ammonia is known to form solid hemi-, mono-, and dihydrate crystal phases under conditions consistent with the surface of Titan and Enceladus, but has also been assigned a role as water-ice antifreeze and methane hydrate inhibitor which is thought to contribute to the outgassing of methane clathrate hydrates into these moons' atmospheres. Here we show, through direct synthesis from solution and vapor deposition experiments under conditions consistent with extraterrestrial planetary atmospheres, that ammonia forms clathrate hydrates and participates synergistically in clathrate hydrate formation in the presence of methane gas at low temperatures. The binary structure II tetrahydrofuran + ammonia, structure I ammonia, and binary structure I ammonia + methane clathrate hydrate phases synthesized have been characterized by X-ray diffraction, molecular dynamics simulation, and Raman spectroscopy methods.

IR Studies of the Spin-Nuclear Conversion in the Vicinity of alpha α - beta β - Transition in Cryodeposited Methane Films

NASA Astrophysics Data System (ADS)

Drobyshev, A.; Aldiyarov, A.; Sokolov, D.; Shinbayeva, A.

2017-06-01

Solid methane belongs to a group of crystals containing hydrogen atoms, whose macroscopic properties are greatly influenced by the spin interaction of hydrogen nuclei. In particular, the methane molecule, which has four protons with spin I=1/2, has three total spin modifications: para-, ortho- and meta-states with three values of the total spin moments of 0, 1 and 2, respectively. Equilibrium concentrations of these modifications and relaxation times are dependent on the temperature, affecting the observed thermal properties of solid methane, such as thermal conductivity, specific heat, thermal expansion. In this paper, we attempt to explain the peculiarities of thin film growth of methane at cryogenic temperatures from the viewpoint of spin-nuclear transformations. Our observations of absorption intensity at a frequency corresponding to 1/2 of the absorption band amplitude of deformation vibrations record a step-like change in the position of the absorption band during the sample deposition process. The observed phenomenon, in our opinion, is the demonstration of spin transformations during deposition.

Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems

PubMed Central

Shin, Kyuchul; Kumar, Rajnish; Udachin, Konstantin A.; Alavi, Saman; Ripmeester, John A.

2012-01-01

There is interest in the role of ammonia on Saturn’s moons Titan and Enceladus as the presence of water, methane, and ammonia under temperature and pressure conditions of the surface and interior make these moons rich environments for the study of phases formed by these materials. Ammonia is known to form solid hemi-, mono-, and dihydrate crystal phases under conditions consistent with the surface of Titan and Enceladus, but has also been assigned a role as water-ice antifreeze and methane hydrate inhibitor which is thought to contribute to the outgassing of methane clathrate hydrates into these moons’ atmospheres. Here we show, through direct synthesis from solution and vapor deposition experiments under conditions consistent with extraterrestrial planetary atmospheres, that ammonia forms clathrate hydrates and participates synergistically in clathrate hydrate formation in the presence of methane gas at low temperatures. The binary structure II tetrahydrofuran + ammonia, structure I ammonia, and binary structure I ammonia + methane clathrate hydrate phases synthesized have been characterized by X-ray diffraction, molecular dynamics simulation, and Raman spectroscopy methods. PMID:22908239

Solid-phase extraction using bis(indolyl)methane-modified silica reinforced with multiwalled carbon nanotubes for the simultaneous determination of flavonoids and aromatic organic acid preservatives.

PubMed

Wang, Na; Liao, Yuan; Wang, Jiamin; Tang, Sheng; Shao, Shijun

2015-12-01

A novel bis(indolyl)methane-modified silica reinforced with multiwalled carbon nanotubes sorbent for solid-phase extraction was designed and synthesized by chemical immobilization of nitro-substituted 3,3'-bis(indolyl)methane on silica modified with multiwalled carbon nanotubes. Coupled with high-performance liquid chromatography analysis, the extraction properties of the sorbent were evaluated for flavonoids and aromatic organic acid compounds. Under optimum conditions, the sorbent can simultaneously extract five flavonoids and two aromatic organic acid preservatives in aqueous solutions in a single-step solid-phase extraction procedure. Wide linear ranges were obtained with correlation coefficients (R(2) ) ranging from 0.9843 to 0.9976, and the limits of detection were in the range of 0.5-5 μg/L for the compounds tested. Compared with the silica modified with multiwalled carbon nanotubes sorbent and the nitro-substituted 3,3'-bis(indolyl)methane-modified silica sorbent, the developed sorbent exhibited higher extraction efficiency toward the selected analytes. The synergistic effect of nitro-substituted 3,3'-bis(indolyl)methane and multiwalled carbon nanotubes not only improved the surface-to-volume ratio but also enhanced multiple intermolecular interactions, such as hydrogen bonds, π-π, and hydrophobic interactions, between the new sorbent and the selected analytes. The as-established solid-phase extraction with high-performance liquid chromatography and diode array detection method was successfully applied to the simultaneous determination of flavonoids and aromatic organic acid preservatives in grape juices with recoveries ranging from 83.9 to 112% for all the selected analytes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Batch and multi-step fed-batch enzymatic saccharification of Formiline-pretreated sugarcane bagasse at high solid loadings for high sugar and ethanol titers.

PubMed

Zhao, Xuebing; Dong, Lei; Chen, Liang; Liu, Dehua

2013-05-01

Formiline pretreatment pertains to a biomass fractionation process. In the present work, Formiline-pretreated sugarcane bagasse was hydrolyzed with cellulases by batch and multi-step fed-batch processes at 20% solid loading. For wet pulp, after 144 h incubation with cellulase loading of 10 FPU/g dry solid, fed-batch process obtained ~150 g/L glucose and ~80% glucan conversion, while batch process obtained ~130 g/L glucose with corresponding ~70% glucan conversion. Solid loading could be further increased to 30% for the acetone-dried pulp. By fed-batch hydrolysis of the dried pulp in pH 4.8 buffer solution, glucose concentration could be 247.3±1.6 g/L with corresponding 86.1±0.6% glucan conversion. The enzymatic hydrolyzates could be well converted to ethanol by a subsequent fermentation using Saccharomices cerevisiae with ethanol titer of 60-70 g/L. Batch and fed-batch SSF indicated that Formiline-pretreated substrate showed excellent fermentability. The final ethanol concentration was 80 g/L with corresponding 82.7% of theoretical yield. Copyright © 2012 Elsevier Ltd. All rights reserved.

Methane production potential of leachate generated from Korean food waste recycling facilities: a lab-scale study.

PubMed

Lee, Dae Hee; Behera, Shishir Kumar; Kim, Ji Won; Park, Hung-Suck

2009-02-01

This paper examines the applicability of food waste leachate (FWL) in bioreactor landfills or anaerobic digesters to produce methane as a sustainable solution to the persisting leachate management problem in Korea. Taking into account the climatic conditions in Korea and FWL characteristics, the effect of key parameters, viz., temperature, alkalinity and salinity on methane yield was investigated. The monthly average moisture content and the ratio of volatile solids to total solids of the FWL were found to be 84% and 91%, respectively. The biochemical methane potential experiment under standard digestion conditions showed the methane yield of FWL to be 358 and 478 ml/g VS after 10 and 28 days of digestion, respectively, with an average methane content of 70%. Elemental analysis showed the chemical composition of FWL to be C(13.02)H(23.01)O(5.93)N(1). The highest methane yield of 403 ml/g VS was obtained at 35 degrees C due to the adaptation of seed microorganisms to mesophilic atmosphere, while methane yields at 25, 45 and 55 degrees C were 370, 351 and 275 ml/g VS, respectively, at the end of 20 days. Addition of alkalinity had a favorable effect on the methane yield. Dilution of FWL with salinity of 2g/l NaCl resulted in 561 ml CH(4)/g VS at the end of 30 days. Considering its high biodegradability (82.6%) and methane production potential, anaerobic digestion of FWL in bioreactor landfills or anaerobic digesters with a preferred control of alkalinity and salinity can be considered as a sustainable solution to the present emergent problem.

Enrichment of denitrifying methane-oxidizing microorganisms using up-flow continuous reactors and batch cultures.

PubMed

Hatamoto, Masashi; Kimura, Masafumi; Sato, Takafumi; Koizumi, Masato; Takahashi, Masanobu; Kawakami, Shuji; Araki, Nobuo; Yamaguchi, Takashi

2014-01-01

Denitrifying anaerobic methane oxidizing (DAMO) microorganisms were enriched from paddy field soils using continuous-flow and batch cultures fed with nitrate or nitrite as a sole electron acceptor. After several months of cultivation, the continuous-flow cultures using nitrite showed remarkable simultaneous methane oxidation and nitrite reduction and DAMO bacteria belonging to phylum NC10 were enriched. A maximum volumetric nitrite consumption rate of 70.4±3.4 mg-N·L(-1)·day(-1) was achieved with very short hydraulic retention time of 2.1 hour. In the culture, about 68% of total microbial cells were bacteria and no archaeal cells were detected by fluorescence in situ hybridization. In the nitrate-fed continuous-flow cultures, 58% of total microbial cells were bacteria while archaeal cells accounted for 7% of total cell numbers. Phylogenetic analysis of pmoA gene sequence showed that enriched DAMO bacteria in the continuous-flow cultivation had over 98% sequence similarity to DAMO bacteria in the inoculum. In contrast, for batch culture, the enriched pmoA gene sequences had 89-91% sequence similarity to DAMO bacteria in the inoculum. These results indicate that electron acceptor and cultivation method strongly affect the microbial community structures of DAMO consortia.

Comparative Analysis of Performance and Microbial Characteristics Between High-Solid and Low-Solid Anaerobic Digestion of Sewage Sludge Under Mesophilic Conditions.

PubMed

Lu, Qin; Yi, Jing; Yang, Dianhai

2016-01-01

High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 high-throughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

Modeling of anaerobic degradation of solid slaughterhouse waste: inhibition effects of long-chain fatty acids or ammonia.

PubMed

Lokshina, L Y; Vavilin, V A; Salminen, E; Rintala, J

2003-01-01

The anaerobic bioconversion of solid poultry slaughterhouse wastes was kinetically investigated. The modified version of simulation model was applied for description of experimental data in mesophilic laboratory digester and assays. Additionally, stages of formation and consumption of long chain fatty acids (LCFA) were included in the model. Batch data on volatile solids, ammonium, acetate, butyrate, propionate, LCFA concentrations, pH level, cumulative volume, and methane partial pressure were used for model calibration. As a reference, the model was used to describe digestion of solid sorted household waste. Simulation results showed that an inhibition of polymer hydrolysis by volatile fatty acids and acetogenesis by NH3 or LCFA could be responsible for the complex system dynamics during degradation of lipid- and protein-rich wastes.

Natural gas hydrates; vast resource, uncertain future

USGS Publications Warehouse

Collett, T.S.

2001-01-01

Gas hydrates are naturally occurring icelike solids in which water molecules trap gas molecules in a cagelike structure known as a clathrate. Although many gases form hydrates in nature, methane hydrate is by far the most common; methane is the most abundant natural gas. The volume of carbon contained in methane hydrates worldwide is estimated to be twice the amount contained in all fossil fuels on Earth, including coal.

Microbiome analysis of dairy cows fed pasture or total mixed ration diets.

PubMed

de Menezes, Alexandre B; Lewis, Eva; O'Donovan, Michael; O'Neill, Brendan F; Clipson, Nicholas; Doyle, Evelyn M

2011-11-01

Understanding rumen microbial ecology is essential for the development of feed systems designed to improve livestock productivity, health and for methane mitigation strategies from cattle. Although rumen microbial communities have been studied previously, few studies have applied next-generation sequencing technologies to that ecosystem. The aim of this study was to characterize changes in microbial community structure arising from feeding dairy cows two widely used diets: pasture and total mixed ration (TMR). Bacterial, archaeal and protozoal communities were characterized by terminal restriction fragment length polymorphism of the amplified SSU rRNA gene and statistical analysis showed that bacterial and archaeal communities were significantly affected by diet, whereas no effect was observed for the protozoal community. Deep amplicon sequencing of the 16S rRNA gene revealed significant differences in the bacterial communities between the diets and between rumen solid and liquid content. At the family level, some important groups of rumen bacteria were clearly associated with specific diets, including the higher abundance of the Fibrobacteraceae in TMR solid samples and members of the propionate-producing Veillonelaceae in pasture samples. This study will be relevant to the study of rumen microbial ecology and livestock feed management. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

The cumulative methane production from dairy cattle slurry can be explained by its volatile solid, temperature and length of storage.

PubMed

Sawamoto, Takuji; Nakamura, Megumi; Nekomoto, Kenji; Hoshiba, Shinji; Minato, Keiko; Nakayama, Motoo; Osada, Takashi

2016-06-01

In order to refine the national estimate of methane emission from stored cattle slurry, it is important to comprehend the basic characteristics of methane production. Two dairy cattle slurries were obtained from livestock farms located in Hokkaido (a northern island) and Kyushu (a southern island). The slurries were diluted with water into three levels: undiluted, three times diluted, and 10 times diluted. Three hundred mL of the slurries were put into a bottle with a headspace volume of 2.0 L, which was filled with nitrogen gas and then sealed by butyl rubber. Four levels of temperature were used for incubation: 35, 25, 15 and 5 °C. The time course of the cumulative methane production per volatile solid (VS) was satisfactorily expressed by an asymptotic regression model. The effect of dilution on the methane production per VS was not distinctive, but that of temperature was of primary importance. In particular, higher temperature yields a higher potential production and a shorter time when the cumulative production reaches half of the potential production. The inclusive and simple models obtained in this study indicate that the cumulative methane production from stored cattle slurry can be explained by VS, temperature and length of storage. © 2015 Japanese Society of Animal Science.

Determination of biogas generation potential as a renewable energy source from supermarket wastes.

PubMed

Alkanok, Gizem; Demirel, Burak; Onay, Turgut T

2014-01-01

Fruit, vegetable, flower waste (FVFW), dairy products waste (DPW), meat waste (MW) and sugar waste (SW) obtained from a supermarket chain were anaerobically digested, in order to recover methane as a source of renewable energy. Batch mesophilic anaerobic reactors were run at total solids (TS) ratios of 5%, 8% and 10%. The highest methane yield of 0.44 L CH4/g VS(added) was obtained from anaerobic digestion of wastes (FVFW+DPW+MW+SW) at 10% TS, with 66.4% of methane (CH4) composition in biogas. Anaerobic digestion of mixed wastes at 5% and 8% TS provided slightly lower methane yields of 0.41 and 0.40 L CH4/g VS(added), respectively. When the wastes were digested alone without co-substrate addition, the highest methane yield of 0.40 L CH4/g VS(added) was obtained from FVFW at 5% TS. Generally, although the volatile solids (VS) conversion percentages seemed low during the experiments, higher methane yields could be obtained from anaerobic digestion of supermarket wastes. A suitable carbon/nitrogen (C/N) ratio, proper adjustment of the buffering capacity and the addition of essential trace nutrients (such as Ni) could improve VS conversion and biogas production yields significantly. Copyright © 2013 Elsevier Ltd. All rights reserved.

Cyclic-Voltammetry-Based Solid-State Gas Sensor for Methane and Other VOC Detection.

PubMed

Gross, Pierre-Alexandre; Jaramillo, Thomas; Pruitt, Beth

2018-05-15

We present the fabrication, characterization, and testing of an electrochemical volatile organic compound (VOC) sensor operating in gaseous conditions at room temperature. It is designed to be microfabricated and to prove the sensing principle based on cyclic voltammetry (CV). It is composed of a working electrode (WE), a counter electrode (CE), a reference electrode (RE), and a Nafion solid-state electrolyte. Nafion is a polymer that conducts protons (H + ) generated from redox reactions from the WE to the CE. The sensor needs to be activated prior to exposure to gases, which consists of hydrating the Nafion layer to enable its ion conduction properties. During testing, we have shown that our sensor is not only capable of detecting methane, but it can also quantify its concentration in the gas flow as well as differentiate its signal from carbon monoxide (CO). These results have been confirmed by exposing the sensor to two different concentrations of methane (50% and 10% of methane diluted in N 2 ), as well as pure CO. Although the signal is positioned in the H ads region of Pt, because of thermodynamic reasons it cannot be directly attributed to methane oxidation into CO 2 . However, its consistency suggests the presence of a methane-related oxidation process that can be used for detection, identification, and quantification purposes.

A sink for methane on Mars? The answer is blowing in the wind

NASA Astrophysics Data System (ADS)

Knak Jensen, Svend J.; Skibsted, Jørgen; Jakobsen, Hans J.; ten Kate, Inge L.; Gunnlaugsson, Haraldur P.; Merrison, Jonathan P.; Finster, Kai; Bak, Ebbe; Iversen, Jens J.; Kondrup, Jens C.; Nørnberg, Per

2014-07-01

Tumbling experiments that mimic the wind erosion of quartz grains in an atmosphere of 13C-enriched methane are reported. The eroded grains are analyzed by 13C and 29Si solid-state NMR techniques after several months of tumbling. The analysis shows that methane has reacted with the eroded surface to form covalent Si-CH3 bonds, which stay intact for temperatures up to at least 250 °C. The NMR findings offer an explanation for the fast disappearance of methane on Mars.

Synergistic co-digestion of solid-organic-waste and municipal-sewage-sludge: 1 plus 1 equals more than 2 in terms of biogas production and solids reduction.

PubMed

Aichinger, Peter; Wadhawan, Tanush; Kuprian, Martin; Higgins, Matthew; Ebner, Christian; Fimml, Christian; Murthy, Sudhir; Wett, Bernhard

2015-12-15

Making good use of existing water infrastructure by adding organic wastes to anaerobic digesters improves the energy balance of a wastewater treatment plant (WWTP) substantially. This paper explores co-digestion load limits targeting a good trade-off for boosting methane production, and limiting process-drawbacks on nitrogen-return loads, cake-production, solids-viscosity and polymer demand. Bio-methane potential tests using whey as a model co-substrate showed diversification and intensification of the anaerobic digestion process resulting in a synergistical enhancement in sewage sludge methanization. Full-scale case-studies demonstrate organic co-substrate addition of up to 94% of the organic sludge load resulted in tripling of the biogas production. At organic co-substrate addition of up to 25% no significant increase in cake production and only a minor increase in ammonia release of ca. 20% have been observed. Similar impacts were measured at a high-solids digester pilot with up-stream thermal hydrolyses where the organic loading rate was increased by 25% using co-substrate. Dynamic simulations were used to validate the synergistic impact of co-substrate addition on sludge methanization, and an increase in hydrolysis rate from 1.5 d(-1) to 2.5 d(-1) was identified for simulating measured gas production rate. This study demonstrates co-digestion for maximizing synergy as a step towards energy efficiency and ultimately towards carbon neutrality. Copyright © 2015 Elsevier Ltd. All rights reserved.

Methane emission by adult ostriches (Struthio camelus).

PubMed

Frei, Samuel; Dittmann, Marie T; Reutlinger, Christoph; Ortmann, Sylvia; Hatt, Jean-Michel; Kreuzer, Michael; Clauss, Marcus

2015-02-01

Ostriches (Struthio camelus) are herbivorous birds with a digestive physiology that shares several similarities with that of herbivorous mammals. Previous reports, however, claimed a very low methane emission from ostriches, which would be clearly different from mammals. If this could be confirmed, ostrich meat would represent a very attractive alternative to ruminant-and generally mammalian-meat by representing a particularly low-emission agricultural form of production. We individually measured, by chamber respirometry, the amount of oxygen consumed as well as carbon dioxide and methane emitted from six adult ostriches (body mass 108.3±8.3 kg) during a 24-hour period when fed a pelleted lucerne diet. While oxygen consumption was in the range of values previously reported for ostriches, supporting the validity of our experimental setup, methane production was, at 17.5±3.2 L d(-1), much higher than previously reported for this species, and was of the magnitude expected for similar-sized, nonruminant mammalian herbivores. These results suggest that methane emission is similar between ostriches and nonruminant mammalian herbivores and that the environmental burden of these animals is comparable. The findings furthermore indicate that it appears justified to use currently available scaling equations for methane production of nonruminant mammals in paleo-reconstructions of methane production of herbivorous dinosaurs. Copyright © 2014. Published by Elsevier Inc.

The performance and microbial diversity of temperature-phased hyperthermophilic and thermophilic anaerobic digestion system fed with organic waste.

PubMed

Lee, M Y; Cheon, J H; Hidaka, T; Tsuno, H

2008-01-01

The objective of this study was to evaluate the performances and microbial diversities for development of the effective hyperthermophilic digester system that consists of a hyperthermophilic reactor and hyperthermophilic or thermophilic reactor in series. Lab-scale reactors were operated continuously fed with artificial kitchen garbage. The effect of temperature on the acidification step was firstly investigated. Results indicated that 20.8% of COD solubilization was achieved at 70 degrees C, with 12.6% at 80 degrees C. The average protein solubilization reached 31% at 80 degrees C. Methane conversion efficiency following the acidification was around 85% on average at 55 degrees C, but decreased with increasing temperature and methane gas was not produced over 73 degrees C. As well, bacteria affiliated with the methanogens dominated the population below 65 degrees C, while those affiliated with acidogens were predominant over 73 degrees C. These results indicated that the hyperthermophilic process has considerable benefits to treat wastewater or waste containing high concentration of protein.

Optimization of solid state anaerobic digestion of the OFMSW by digestate recirculation: A new approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michele, Pognani, E-mail: michele.pognani@unimi.it; Giuliana, D’Imporzano, E-mail: giuliana.dimporzano@unimi.it; Gruppo Ricicla - DiSAA, Università degli Studi di Milano, Biomass and Bioenergy Lab., Parco Tecnologico Padano, Via Einstein, Loc. C.na Codazza, 26900 Lodi

2015-01-15

Highlights: • Solid State Anaerobic Digestion (SSAD) of OFMSW can be optimized by irrigation with digestate. • Digestate spreading allows keeping optimal process parameters and high hydrolysis rate. • The 18.4% of CH{sub 4} was produced in the reactor, leaving the 49.7% in the percolate. • Successive CSTR feed with percolate shows a biogas enriched in methane (more than 80%). • The proposed process allow producing the 68% of OFMSW potential CH{sub 4}, getting high quality organic amendment. - Abstract: Dry anaerobic digestion (AD) of OFMSW was optimized in order to produce biogas avoiding the use of solid inoculum. Doingmore » so the dry AD was performed irrigating the solid waste with liquid digestate (flow rate of 1:1.18–1:0.9 w/w waste/digestate; 21 d of hydraulic retention time – HRT) in order to remove fermentation products inhibiting AD process. Results indicated that a high hydrolysis rate of organic matter (OM) and partial biogas production were obtained directly during the dry AD. Hydrolysate OM was removed from digester by the percolate flow and it was subsequently used to feed a liquid anaerobic digester. During dry AD a total loss of 36.9% of total solids was recorded. Methane balance indicated that 18.4% of potential methane can be produced during dry AD and 49.7% by the percolate. Nevertheless results obtained for liquid AD digestion indicated that only 20.4% and 25.7% of potential producible methane was generated by adopting 15 and 20 days of HRT, probably due to the AD inhibition due to high presence of toxic ammonia forms in the liquid medium.« less

Study on biomethane production and biodegradability of different leafy vegetables in anaerobic digestion.

PubMed

Yan, Hu; Zhao, Chen; Zhang, Jiafu; Zhang, Ruihong; Xue, Chunyu; Liu, Guangqing; Chen, Chang

2017-12-01

Enormous amounts of vegetable residues are wasted annually, causing many environmental problems due to their high moisture and organic contents. In this study, the methane production potential of 20 kinds of typical leafy vegetable residues in China were explored using a unified method. A connection between the biochemical components and the methane yields of these vegetables was well established which could be used to predict biogas performance in practice. A high volatile solid/total solid (VS/TS) ratio and hemicellulose content exhibited a positive impact on the biogas yield while lignin had a negative impact. In addition, three kinetic models were used to describe the methane production process of these agro-wastes. The systematic comparison of the methane production potentials of these leafy vegetables shown in this study will not only serve as a reference for basic research on anaerobic digestion but also provide useful data and information for agro-industrial applications of vegetable residues in future work.

Impact of cell design and operating conditions on the performances of SOFC fuelled with methane

NASA Astrophysics Data System (ADS)

Laurencin, J.; Lefebvre-Joud, F.; Delette, G.

An in-house-model has been developed to study the thermal and electrochemical behaviour of a planar SOFC fed directly with methane and incorporated in a boiler. The usual Ni-YSZ cermet has been considered for the anode material. It has been found that methane reforming into hydrogen occurs only at the cell inlet in a limited depth within the anode. A sensitivity analysis has allowed establishing that anode thicknesses higher than ∼400-500 μm are required to achieve both the optimal methane conversion and electrochemical performances. The direct internal reforming (DIR) mechanisms and the impact of operating conditions on temperature gradients and SOFC electrical efficiencies have been investigated considering the anode supported cell configuration. It has been shown that the temperature gradient is minimised in the autothermal mode of cell operation. Thermal equilibrium in the stack has been found to be strongly dependent on radiative heat losses with the stack envelope. Electrochemical performance and cell temperature maps have been established as a function of methane flow rates and cell voltages.

Effects of forage type and extruded linseed supplementation on methane production and milk fatty acid composition of lactating dairy cows.

PubMed

Livingstone, K M; Humphries, D J; Kirton, P; Kliem, K E; Givens, D I; Reynolds, C K

2015-06-01

Replacing dietary grass silage (GS) with maize silage (MS) and dietary fat supplements may reduce milk concentration of specific saturated fatty acids (SFA) and can reduce methane production by dairy cows. The present study investigated the effect of feeding an extruded linseed supplement on milk fatty acid (FA) composition and methane production of lactating dairy cows, and whether basal forage type, in diets formulated for similar neutral detergent fiber and starch, altered the response to the extruded linseed supplement. Four mid-lactation Holstein-Friesian cows were fed diets as total mixed rations, containing either high proportions of MS or GS, both with or without extruded linseed supplement, in a 4×4 Latin square design experiment with 28-d periods. Diets contained 500 g of forage/kg of dry matter (DM) containing MS and GS in proportions (DM basis) of either 75:25 or 25:75 for high MS or high GS diets, respectively. Extruded linseed supplement (275 g/kg ether extract, DM basis) was included in treatment diets at 50 g/kg of DM. Milk yields, DM intake, milk composition, and methane production were measured at the end of each experimental period when cows were housed in respiration chambers. Whereas DM intake was higher for the MS-based diet, forage type and extruded linseed had no significant effect on milk yield, milk fat, protein, or lactose concentration, methane production, or methane per kilogram of DM intake or milk yield. Total milk fat SFA concentrations were lower with MS compared with GS-based diets (65.4 vs. 68.4 g/100 g of FA, respectively) and with extruded linseed compared with no extruded linseed (65.2 vs. 68.6 g/100 g of FA, respectively), and these effects were additive. Concentrations of total trans FA were higher with MS compared with GS-based diets (7.0 vs. 5.4 g/100 g of FA, respectively) and when extruded linseed was fed (6.8 vs. 5. 6g/100 g of FA, respectively). Total n-3 FA were higher when extruded linseed was fed compared with no extruded linseed (1.2 vs. 0.8 g/100 g of FA, respectively), whereas total n-6 polyunsaturated FA were higher when feeding MS compared with GS (2.5 vs. 2.1 g/100 g of FA, respectively). Feeding extruded linseed and MS both provided potentially beneficial decreases in SFA concentration of milk, and no significant interactions were found between extruded linseed supplementation and forage type. However, both MS and extruded linseed increased trans FA concentration in milk fat. Neither MS nor extruded linseed had significant effects on methane production or yield, but the amounts of supplemental lipid provided by extruded linseed were relatively small. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Municipal solid waste characterization and its assessment for potential methane generation: a case study.

PubMed

Mor, Suman; Ravindra, Khaiwal; De Visscher, Alex; Dahiya, R P; Chandra, A

2006-12-01

There has been a significant increase in municipal solid waste (MSW) generation in India during the last few decades and its management has become a major issue because the poor waste management practices affect the health and amenity of the cities. In the present study, various physico-chemical parameters of the MSW were analyzed to characterize the waste dumped at Gazipur landfill site in Delhi, India, which shows that it contains a high fraction of degradable organic components. The decomposition of organic components produces methane, a significant contributor to global warming. Based on the waste composition, waste age and the total amount dumped, a first-order decay model (FOD) was applied to estimate the methane generation potential of the Gazipur landfill site, which yields an estimate of 15.3 Gg/year. This value accounts to about 1-3% of existing Indian landfill methane emission estimates. Based on the investigation of Gazipur landfill, we estimate Indian landfill methane emissions at 1.25 Tg/year or 1.68 Tg/year of methane generation potential. These values are within the range of existing estimates. A comparison of FOD with a recently proposed triangular model was also performed and it shows that both models can be used for the estimation of methane generation. However, the decrease of the emission after closure is more gradual in the case of the first-order model, leading to larger gas production predictions after more than 10 years of closure. The regional and global implications of national landfill methane emission are also discussed.

Genome-Scale Metabolic Reconstructions and Theoretical Investigation of Methane Conversion in Methylomicrobium buryatense Strain 5G(B1)

DOE PAGES

de la Torre, Andrea; Metivier, Aisha; Chu, Frances; ...

2015-11-25

Methane-utilizing bacteria (methanotrophs) are capable of growth on methane and are attractive systems for bio-catalysis. However, the application of natural methanotrophic strains to large-scale production of value-added chemicals/biofuels requires a number of physiological and genetic alterations. An accurate metabolic model coupled with flux balance analysis can provide a solid interpretative framework for experimental data analyses and integration.

Development of Carbon and Sulphur Tolerant Anodes of Solid Oxide Fuel Cells

DTIC Science & Technology

2010-01-14

LSCM/YSZ) composite anode is investigated in detail for the direct utilization of ethanol and methane (the main component of natural gas) in SOFCs...Impregnation of Pd nanoparticles significantly promotes the electrocatalytic activity of LSCM/YSZ composite anodes for the ethanol and methane... electrooxidation reaction. At 800°C, the electrode polarization resistance for the methane oxidation is reduced by a factor of 3 after impregnation of 0.10

Thermochemical Pretreatment for Anaerobic Digestion of Sorted Waste

NASA Astrophysics Data System (ADS)

Hao, W.; Hongtao, W.

2008-02-01

The effect of alkaline hydrothermal pre-treatment for anaerobic digestion of mechanically-sorted municipal solid waste (MSW) and source-sorted waste was studied. Waste was hydrothermally pre-treated in dilute alkali solution. Hydrolysis product was incubated in 500 ml saline bottle to determine methane potential (MP) under mesospheric anaerobic conditions. Optimum reaction condition obtained in the study is 170 °C at the dose of 4 g NaOH/100 g solid for one hour. Soluble COD was 13936 mg/L and methane yield was 164 ml/g VS for 6 days incubation at optimum conditions. More than 50% biogas increase was achieved over the control, and methane conversion ratio on carbon basis was enhanced to 30.6%. The digestion period was less than 6 days when pre-treatment temperature was above 130 °C. The organic part of sorted waste is mainly constituted of kitchen garbage and leaf. Model kitchen garbage was completely liquidized at 130 °C for one hour and the methane yield was 276 ml/g VS. Addition of alkali enhance hydroxylation rate and methane yield slightly. The biogas potential of leaf could be observed by pre-treatment above 150 °C under alkaline condition.

Treatment of Produced Water From Coal-Bed Methane Production Using Capacitive Deionization Final Report CRADA No. TSV-1380-97

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tran, T. D.; Patton, C. C.

The production af Coal-Bed Methane (CBM) is always accompanied by the production of large amounts of water. The produced water is typically too high in dissolved solids and salinity to be suitable for surface disposal.

Effect of temperature on methane production from field-scale anaerobic digesters treating dairy manure.

PubMed

Arikan, Osman A; Mulbry, Walter; Lansing, Stephanie

2015-09-01

Temperature is a critical factor affecting anaerobic digestion because it influences both system heating requirements and methane production. Temperatures of 35-37°C are typically suggested for manure digestion. In temperate climates, digesters require a considerable amount of additional heat energy to maintain temperatures at these levels. In this study, the effects of lower digestion temperatures (22 and 28°C), on the methane production from dairy digesters were evaluated and compared with 35°C using duplicate replicates of field-scale (FS) digesters with a 17-day hydraulic retention time. After acclimation, the FS digesters were operated for 12weeks using solids-separated manure at an organic loading rate (OLR) of 1.4kgVSm(-3)d(-1) and then for 8weeks using separated manure amended with manure solids at an OLR of 2.6kgVSm(-3)d(-1). Methane production values of the FS digesters at 22 and 28°C were about 70% and 87%, respectively, of the values from FS digesters at 35°C. The results suggest that anaerobic digesters treating dairy manure at 28°C were nearly as efficient as digesters operated at 35°C, with 70% of total methane achievable at 22°C. These results are relevant to small farms interested in anaerobic digestion for methane reduction without heat recovery from generators or for methane recovery from covered lagoon digesters. Copyright © 2015 Elsevier Ltd. All rights reserved.

Copper enhances the activity and salt resistance of mixed methane-oxidizing communities.

PubMed

van der Ha, David; Hoefman, Sven; Boeckx, Pascal; Verstraete, Willy; Boon, Nico

2010-08-01

Effluents of anaerobic digesters are an underestimated source of greenhouse gases, as they are often saturated with methane. A post-treatment with methane-oxidizing bacterial consortia could mitigate diffuse emissions at such sites. Semi-continuously fed stirred reactors were used as model systems to characterize the influence of the key parameters on the activity of these mixed methanotrophic communities. The addition of 140 mg L(-1) NH (4) (+) -N had no significant influence on the activity nor did a temperature increase from 28 degrees C to 35 degrees C. On the other hand, addition of 0.64 mg L(-1) of copper(II) increased the methane removal rate by a factor of 1.5 to 1.7 since the activity of particulate methane monooxygenase was enhanced. The influence of different concentrations of NaCl was also tested, as effluents of anaerobic digesters often contain salt levels up to 10 g NaCl L(-1). At a concentration of 11 g NaCl L(-1), almost no methane-oxidizing activity was observed in the reactors without copper addition. Yet, reactors with copper addition exhibited a sustained activity in the presence of NaCl. A colorimetric test based on naphthalene oxidation showed that soluble methane monooxygenase was inhibited by copper, suggesting that the particulate methane monooxygenase was the active enzyme and thus more salt resistant. The results obtained demonstrate that the treatment of methane-saturated effluents, even those with increased ammonium (up to 140 mg L(-1) NH (4) (+) -N) and salt levels, can be mitigated by implementation of methane-oxidizing microbial consortia.

New roughage source of Pennisetum purpureum cv. Mahasarakham utilization for ruminants feeding under global climate change.

PubMed

Wanapat, Metha; Mapato, Chaowarit

2018-05-31

As the climate changes, it influences ruminant's feed intake, nutrient digestibility, rumen methane production and emission. This experiment aimed to evaluate the effect of feeding Sweet grass (Pennisetum purpureum cv. Mahasarakham) as a new source of good quality forage to improve feed utilization efficiency and to mitigate rumen methane production and emission. Four, growing crossbred of Holstein Friesian heifers, 14 months old, were arranged in a 4 x 4 Latin square design to receive four dietary treatments. Treatment 1 (T1) was rice straw (RS) fed on ad libitum with 1.0 % BW of concentrate (C) supplementation (RS/1.0C). Treatment 2 (T2) and treatment 3 (T3) were Sweet grass (SG), fed on ad libitum with 1.0 and 0.5 %BW of concentrate supplementation, respectively (SG/1.0C and SG/0.5C, respectively). Treatment 4 (T4) was total Sweet grass fed on ad libitum basis with non-concentrate supplementation (TSG). The results revealed that roughage and total feed intake were increased with SG when compared to RS (P<0.01) while TSG was similar to RS/1.0C treatment. Digestibility of nutrients, nutrients intake, total VFAs, rumen microorganisms were the highest and CH4 was the lowest in the heifers received SG/1.0C (P<0.01). Total DM feed intake, digestibility and intake of nutrients, total VFAs, NH3-N, bacterial and fungal population of animals receiving SG/0.5C were higher than those fed on RS/1.0C. Reducing of concentrate supplementation with SG as a roughage source increased NH3-N, acetic acid, and fungal populations, but it decreased propionic acid and protozoal populations (P<0.05). However, ruminal pH and blood urea nitrogen were not affected by the dietary treatments (P>0.05). As the results, Sweet grass could be a good forage to improve rumen fermentation, decrease methane production and reduced the level of concentrate supplementation for growing ruminants in the tropics especially under global climate change.

Improved design of anaerobic digesters for household biogas production in indonesia: one cow, one digester, and one hour of cooking per day.

PubMed

Usack, Joseph G; Wiratni, Wiratni; Angenent, Largus T

2014-01-01

A government-sponsored initiative in Indonesia to design and implement low-cost anaerobic digestion systems resulted in 21 full-scale systems with the aim to satisfy the cooking fuel demands of rural households owning at least one cow. The full-scale design consisted of a 0.3 m diameter PVC pipe, which was operated as a conventional plug-flow system. The system generated enough methane to power a cooking stove for ∼ 1 h. However, eventual clogging from solids accumulation inside the bioreactor proved to be a major drawback. Here, we improved the digester configuration to remedy clogging while maintaining system performance. Controlled experiments were performed using four 9-L laboratory-scale digesters operated at a temperature of 27 ± 1 °C, a volatile solids loading rate of 2.0 g VS · L(-1) · day(-1), and a 21-day hydraulic retention time. Two of the digesters were replicates of the original design (control digesters), while the other two digesters included internal mixing or effluent recycle (experimental digesters). The performance of each digester was compared based on methane yields, VS removal efficiencies, and steady-state solids concentrations during an operating period of 311 days. Statistical analyses revealed that internal mixing and effluent recycling resulted in reduced solids accumulation compared to the controls without diminishing methane yields or solids removal efficiencies.

Mitigation of methane production from cattle by feeding cashew nut shell liquid.

PubMed

Shinkai, T; Enishi, O; Mitsumori, M; Higuchi, K; Kobayashi, Y; Takenaka, A; Nagashima, K; Mochizuki, M; Kobayashi, Y

2012-09-01

The effects of cashew nut shell liquid (CNSL) feeding on methane production and rumen fermentation were investigated by repeatedly using 3 Holstein nonlactating cows with rumen fistulas. The cows were fed a concentrate and hay diet (6:4 ratio) for 4 wk (control period) followed by the same diet with a CNSL-containing pellet for the next 3 wk (CNSL period). Two trials were conducted using CNSL pellets blended with only silica (trial 1) or with several other ingredients (trial 2). Each pellet type was fed to cows to allow CNSL intake at 4 g/100 kg of body weight per day. Methane production was measured in a respiration chamber system, and energy balance, nutrient digestibility, and rumen microbial changes were monitored. Methane production per unit of dry matter intake decreased by 38.3 and 19.3% in CNSL feeding trials 1 and 2, respectively. Energy loss as methane emission decreased from 9.7 to 6.1% (trial 1) and from 8.4 to 7.0% (trial 2) with CNSL feeding, whereas the loss to feces (trial 1) and heat production (trial 2) increased. Retained energy did not differ between the control and CNSL periods. Digestibility of dry matter and gross energy decreased with CNSL feeding in trial 1, but did not differ in trial 2. Feeding CNSL caused a decrease in acetate and total short-chain fatty acid levels and an increase in propionate proportion in both trials. Relative copy number of methyl coenzyme-M reductase subunit A gene and its expression decreased with CNSL feeding. The relative abundance of fibrolytic or formate-producing species such as Ruminococcus flavefaciens, Butyrivibrio fibrisolvens, and Treponema bryantii decreased, but species related to propionate production, including Prevotella ruminicolla, Selenomonas ruminantium, Anaerovibrio lipolytica, and Succinivibrio dextrinosolvens, increased. If used in a suitable formulation, CNSL acts as a potent methane-inhibiting and propionate-enhancing agent through the alteration of rumen microbiota without adversely affecting feed digestibility. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Nitrate but not tea saponin feed additives decreased enteric methane emissions in nonlactating cows.

PubMed

Guyader, J; Eugène, M; Doreau, M; Morgavi, D P; Gérard, C; Loncke, C; Martin, C

2015-11-01

Tea saponin is considered a promising natural compound for reducing enteric methane emissions in ruminants. A trial was conducted to study the effect of this plant extract fed alone or in combination with nitrate on methane emissions, total tract digestive processes, and ruminal characteristics in cattle. The experiment was conducted as a 2 × 2 factorial design with 4 ruminally cannulated nonlactating dairy cows. Feed offer was restricted to 90% of voluntary intake and diets consisted of (DM basis): 1) control (CON; 50% hay and 50% pelleted concentrates), 2) CON with 0.5% tea saponin (TEA), 3) CON with 2.3% nitrate (NIT), and 4) CON with 0.5% tea saponin and 2.3% nitrate (TEA+NIT). Tea saponin and nitrate were included in pelleted concentrates. Diets contained similar amounts of CP (12.2%), starch (26.0%), and NDF (40.1%). Experimental periods lasted 5 wk including 2 wk of measurement (wk 4 and 5), during which intake was measured daily. In wk 4, daily methane emissions were quantified for 4 d using open circuit respiratory chambers. In wk 5, total tract digestibility, N balance, and urinary excretion of purine derivatives were determined from total feces and urine collected separately for 6 d. Ruminal fermentation products and protozoa concentration were analyzed from samples taken after morning feeding for 2 nonconsecutive days in wk 5. Tea saponin and nitrate supplementation decreased feed intake ( < 0.05), with an additive effect when fed in combination. Compared with CON, tea saponin did not modify methane emissions (g/kg DMI; > 0.05), whereas nitrate-containing diets (NIT and TEA+NIT) decreased methanogenesis by 28%, on average ( < 0.001). Total tract digestibility, N balance, and urinary excretion of purine derivatives were similar among diets. Ruminal fermentation products were not affected by tea saponin, whereas nitrate-containing diets increased acetate proportion and decreased butyrate proportion and ammonia concentration ( < 0.05). Under the experimental conditions tested, we confirmed the antimethanogenic effect of nitrate, whereas tea saponin alone included in pelleted concentrates failed to decrease enteric methane emissions in nonlactating dairy cows.

Feasibility of biogas production from anaerobic co-digestion of herbal-extraction residues with swine manure.

PubMed

Li, Yan; Yan, Xi-Luan; Fan, Jie-Ping; Zhu, Jian-Hang; Zhou, Wen-Bin

2011-06-01

The objective of this work was to examine the feasibility of biogas production from the anaerobic co-digestion of herbal-extraction residues with swine manure. Batch and semi-continuous experiments were carried out under mesophilic anaerobic conditions. Batch experiments revealed that the highest specific biogas yield was 294 mL CH(4) g(-1) volatile solids added, obtained at 50% of herbal-extraction residues and 3.50 g volatile solids g(-1) mixed liquor suspended solids. Specific methane yield from swine manure alone was 207 mL CH(4) g(-1) volatile solid added d(-1) at 3.50 g volatile solids g(-1) mixed liquor suspended solids. Furthermore, specific methane yields were 162, 180 and 220 mL CH(4) g (-1) volatile solids added d(-1) for the reactors co-digesting mixtures with 10%, 25% and 50% herbal-extraction residues, respectively. These results suggested that biogas production could be enhanced efficiently by the anaerobic co-digestion of herbal-extraction residues with swine manure. Copyright © 2011 Elsevier Ltd. All rights reserved.

Methane emissions measured at two California landfills by OTM-10 and an acetylene tracer method

EPA Science Inventory

Methane emissions were measured at two municipal solid waste landfills in California using static flux chambers, an optical remote sensing approach known as vertical radial plume mapping (VRPM) using a tunable diode laser (TDL) and a novel acetylene tracer method. The tracer meth...

Methane and Hydrogen Production from Anaerobic Fermentation of Municipal Solid Wastes

NASA Astrophysics Data System (ADS)

Kobayashi, Takuro; Lee, Dong-Yeol; Xu, Kaiqin; Li, Yu-You; Inamori, Yuhei

Methane and hydrogen production was investigated in batch experiments of thermophilic methane and hydrogen fermentation, using domestic garbage and food processing waste classified by fat/carbohydrate balance as a base material. Methane production per unit of VS added was significantly positively correlated with fat content and negatively correlated with carbohydrate content in the substrate, and the average value of the methane production per unit of VS added from fat-rich materials was twice as large as that from carbohydrate-rich materials. By contrast, hydrogen production per unit of VS added was significantly positively correlated with carbohydrate content and negatively correlated with fat content. Principal component analysis using the results obtained in this study enable an evaluation of substrates for methane and hydrogen fermentation based on nutrient composition.

Determination of as-discarded methane potential in residential and commercial municipal solid waste.

PubMed

Chickering, Giles W; Krause, Max J; Townsend, Timothy G

2018-06-01

Methane generation potential, L 0 , is a primary parameter of the first-order decay (FOD) model used for prediction and regulation of landfill gas (LFG) generation in municipal solid waste (MSW) landfills. The current US EPA AP-42 default value for L 0 , which has been in place for almost 20 years, is 100 m 3 CH 4 /Mg MSW as-discarded. Recent research suggests the yield of landfilled waste could be less than 60 m 3 CH 4 /Mg MSW. This study aimed to measure the L 0 of present-day residential and commercial as-discarded MSW. In doing so, 39 waste collection vehicles were sorted for composition before samples of each biodegradable fraction were analyzed for methane generation potential. Methane yields were determined for over 450 samples of 14 different biodegradable MSW fractions, later to be combined with moisture content and volatile solids data to calculate L 0 values for each waste load. An average value of 80 m 3 CH 4 /Mg MSW was determined for all samples with 95% of values in the interval 74-86 m 3 CH 4 /Mg MSW as-discarded. While no statistically significant difference was observed, commercial MSW yields (mean 85, median 88 m 3 CH 4 /Mg MSW) showed a higher average L 0 than residential MSW (mean 75, median 71 m 3 CH 4 /Mg MSW). Many methane potential values for individual fractions described in previous work were found within the range of values determined by BMP in this study. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thermophilic Dry Methane Fermentation of Distillation Residue Eluted from Ethanol Fermentation of Kitchen Waste and Dynamics of Microbial Communities.

PubMed

Huang, Yu-Lian; Tan, Li; Wang, Ting-Ting; Sun, Zhao-Yong; Tang, Yue-Qin; Kida, Kenji

2017-01-01

Thermophilic dry methane fermentation is advantageous for feedstock with high solid content. Distillation residue with 65.1 % moisture content was eluted from ethanol fermentation of kitchen waste and subjected to thermophilic dry methane fermentation, after adjusting the moisture content to 75 %. The effect of carbon to nitrogen (C/N) ratio on thermophilic dry methane fermentation was investigated. Results showed that thermophilic dry methane fermentation could not be stably performed for >10 weeks at a C/N ratio of 12.6 and a volatile total solid (VTS) loading rate of 1 g/kg sludge/d; however, it was stably performed at a C/N ratio of 19.8 and a VTS loading rate of 3 g/kg sludge/d with 83.4 % energy recovery efficiency. Quantitative PCR analysis revealed that the number of bacteria and archaea decreased by two orders of magnitude at a C/N ratio of 12.6, whereas they were not influenced at a C/N ratio of 19.8. Microbial community analysis revealed that the relative abundance of protein-degrading bacteria increased and that of organic acid-oxidizing bacteria and acetic acid-oxidizing bacteria decreased at a C/N ratio of 12.6. Therefore, there was accumulation of NH 4 + and acetic acid, which inhibited thermophilic dry methane fermentation.

Dietary fat sources affect feed intake, digestibility, rumen microbial populations, energy partition and methane emissions in different beef cattle genotypes.

PubMed

Kaewpila, C; Sommart, K; Mitsumori, M

2018-03-20

The mitigation of enteric methane emission in beef cattle production is important for reducing feed energy loss and increasing environmental sustainability. The main objective of this study was to evaluate the effect of different oilseeds included in fermented total mixed rations (whole soyabean seed (SBS, control), whole kapok seed (KPS) and cracked oil palm fruit (OPF)) on feed intake, digestibility, rumen microbial populations, energy partition and methane emissions in different cattle genotypes (Charolais crossbred v. Japanese Black crossbred). Three Charolais crossbred and three Japanese Black crossbred bulls were studied in a replicated 3×3 Latin square experimental design; genotypes were analysed in separate squares including three periods of 21 days each and three dietary oilseed treatments fed ad libitum. The cattle were placed in a metabolic cage equipped with a ventilated head box respiration system for evaluating digestibility and energy balance. As compared with Charolais crossbred individuals, Japanese Black crossbred bulls showed consistently lower dry matter intake (15.5%, P0.05) or diet (P>0.05) under the experimental conditions and ranged from 5.8% to 6.0% of gross energy intake. This value is lower than that reported by the Intergovernmental Panel on Climate Change (6.5%) for cattle fed with low-quality crop residues or by-products. Thus, our results imply that the Japanese Black crossbred cattle consume less feed and emits less enteric methane than the Charolais crossbred does, mainly owing to its lower ME requirement for maintenance. The OPF diet could be used to replace SBS for high beef production, although further studies are required to evaluate their application across a wide range of beef production systems.

Effects of quebracho tannin extract on intake, digestibility, rumen fermentation, and methane production in crossbred heifers fed low-quality tropical grass.

PubMed

Piñeiro-Vázquez, A T; Jiménez-Ferrer, G; Alayon-Gamboa, J A; Chay-Canul, A J; Ayala-Burgos, A J; Aguilar-Pérez, C F; Ku-Vera, J C

2018-01-01

The aim of this work was to evaluate the effect of quebracho tannins extract (QTE) on feed intake, dry matter (DM) digestibility, and methane (CH 4 ) emissions in cattle fed low-quality Pennisetum purpureum grass. Five heifers (Bos taurus × Bos indicus) with an average live weight (LW) of 295 ± 19 kg were allotted to five treatments (0, 1, 2, 3, and 4% QTE/kg DM) in a 5 × 5 Latin square design. Intake, digestibility, and total methane emissions (L/day) were recorded for periods of 23 h when cattle were housed in open-circuit respiration chambers. Dry matter intake (DMI), organic matter intake (OMI), dry matter digestibility (DMD), and organic matter digestibility (OMD) were different between treatments with 0 and 4% of QTE/kg DM (P < 0.05). Total volatile fatty acid and the molar proportion of acetate in the rumen was not affected (P < 0.05); however, the molar proportion of propionate increased linearly (P < 0.01) for treatments with 3 and 4% QTE. Total CH 4 production decreased linearly (P < 0.01) as QTE increased in the diet, particularly with 3 and 4% concentration. When expressed as DMI and OMI by CH 4 , production (L/kg) was different between treatments with 0 vs 3 and 4% QTE (P < 0.05). It is concluded that the addition of QTE at 2 or 3% of dry matter ration can decrease methane production up to 29 and 41%, respectively, without significantly compromising feed intake and nutrients digestibility.

Tea saponin reduced methanogenesis in vitro but increased methane yield in lactating dairy cows.

PubMed

Guyader, J; Eugène, M; Doreau, M; Morgavi, D P; Gérard, C; Martin, C

2017-03-01

The effect of tea saponin supplementation in the ruminant diet on methane emissions, rumen fermentation, and digestive processes is still under debate. The objective of this study was to assess the effect of this plant extract on methanogenesis, total-tract digestibility, and lactating performances of dairy cows. The work included 2 independent and successive experiments. First, the effect of 7 tea saponin doses (from 0 to 0.50 g/L) on methane emissions and protozoa concentrations was tested in 2 repeated in vitro batch culture incubations using bovine rumen contents as inoculum and a cereal mixture as substrate. After 18 h of incubation, total gas production and composition as well as rumen fermentation parameters and protozoa concentration were analyzed. Increasing dosage of the plant extract reduced methane production and protozoa concentration, with a maximum reduction of 29% for CH 4 (mL/g of substrate) and 51% for protozoa (10 5 /mL). Tea saponin did not affect volatile fatty acids concentration, but marginally decreased total gas production by 5% at the highest dose. Second, a 2-period crossover design experiment was carried out with 8 lactating dairy cows fed a basal diet (54% corn silage, 6% hay, and 40% pelleted concentrates on a dry matter basis) without (control) or with 0.52% tea saponin (TSP). Each experimental period lasted 5 wk. Animals were fed ad libitum during the first 3 wk of the period (wk 1, 2, and 3) and restricted (95% of ad libitum intake) during the last 2 wk (wk 4 and 5). Intake and milk production were recorded daily. Methane emissions were quantified using open chambers (2 d, wk 4). Total-tract digestibility and nitrogen balance were determined from total feces and urine collected separately (5 d, wk 5). Rumen fermentation parameters and protozoa concentration were analyzed from samples taken after morning feeding (1 d, wk 5). Milk production, dry matter intake, and feed efficiency were reduced with TSP (-18, -12, and -8%, respectively). As daily methane production (g/d) was not affected, methane emissions (g/kg of dry matter intake) increased by 14% with TSP. Total-tract digestibility and nitrogen balance were similar between diets, except for acid detergent fiber digestibility, which tended to be improved with TSP (+4 percentage units). Rumen fermentation parameters and protozoa concentration were relatively unchanged by diets. Under the conditions of this experiment, tea saponin is not efficient to reduce methane emissions from dairy cows. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Generating Aromatics From CO2 on Mars or Natural Gas on Earth

NASA Technical Reports Server (NTRS)

Muscatello, Anthony C.; Zubrin, Robert; Berggren, Mark

2006-01-01

Methane to aromatics on Mars ( METAMARS ) is the name of a process originally intended as a means of converting Martian atmospheric carbon dioxide to aromatic hydrocarbons and oxygen, which would be used as propellants for spacecraft to return to Earth. The process has been demonstrated on Earth on a laboratory scale. A truncated version of the process could be used on Earth to convert natural gas to aromatic hydrocarbon liquids. The greater (relative to natural gas) density of aromatic hydrocarbon liquids makes it more economically feasible to ship them to distant markets. Hence, this process makes it feasible to exploit some reserves of natural gas that, heretofore, have been considered as being "stranded" too far from markets to be of economic value. In the full version of METAMARS, carbon dioxide is frozen out of the atmosphere and fed to a Sabatier reactor along with hydrogen (which, on Mars, would have been brought from Earth). In the Sabatier reactor, these feedstocks are converted to methane and water. The water is condensed and electrolyzed to oxygen (which is liquefied) and hydrogen (which is recycled to the Sabatier reactor). The methane is sent to an aromatization reactor, wherein, over a molybdenum-on-zeolite catalyst at a temperature 700 C, it is partially converted into aromatic hydrocarbons (specifically, benzene, toluene, and naphthalene) along with hydrogen. The aromatics are collected by freezing, while unreacted methane and hydrogen are separated by a membrane. Most of the hydrogen is recycled to the Sabatier reactor, while the methane and a small portion of the hydrogen are recycled to the aromatization reactor. The partial recycle of hydrogen to the aromatization reactor greatly increases the catalyst lifetime and eases its regeneration by preventing the formation of graphitic carbon, which could damage the catalyst. (Moreover, if graphitic carbon were allowed to form, it would be necessary to use oxygen to remove it.) Because the aromatics contain only one hydrogen atom per carbon atom, METAMARS produces four times as much propellant from a given amount of hydrogen as does a related process that includes the Sabatier reaction and electrolysis but not aromatization. In the terrestrial version of METAMARS, the Sabatier reactor and electrolyzer would be omitted, while the hydrogen/ methane membrane-separating membrane, the aromatization reactor, and the unreacted-gas-recycling subsystem would be retained. Natural gas would be fed directly to the aromatization reactor. Because natural gas consists of higher hydrocarbons in addition to methane, the aromatization subprocess should be more efficient than it is for methane alone.

Methane digester for wastewater grown aquatic plants. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1976-01-01

The purpose of this project was to build and test a small-scale, prototype anaerobic digester using wastewater grown aquatic plants as feed stock. Two 150 gal. digesters of the horizontal ''bag'' shape were constructed and fed with water hyacinths and duckweed plants grown on wastewater. Bio-films were added to increase methane bacteria surface attachment area, and solar heating was used to increase operating temperatures. Repeated difficulties were encountered with the low cost materials and construction techniques used, causing leaks of liquids and methane gas, and in the solar heat exchanger. As a consequence, no reliable data were obtained on performance.more » Due to an inadequate budget, the project was terminated without making construction changes needed to properly operate the system for a long period of time. 15 refs., 7 figs.« less

Modelling global methane emissions from livestock: Biological and nutritional controls

NASA Technical Reports Server (NTRS)

Johnson, Donald E.

1992-01-01

The available observations of methane production from the literature have been compiled into a ruminant methane data base. This data base includes 400 treatment mean observations of methane losses from cattle and sheep, and minor numbers of measurements from other species. Methane loss varied from 2.0 to 11.6 percent of dietary gross energy. Measurements included describe the many different weights and physiological states of the animals fed and diets ranging from all forage to all concentrate diets or mixtures. An auxiliary spreadsheet lists approximately 1000 individual animal observations. Many important concepts have emerged from our query and analysis of this data set. The majority of the world's cattle, sheep, and goats under normal husbandry circumstances likely produce methane very close to 6 percent of their daily diets gross energy (2 percent of the diet by weight). Although individual animals or losses from specific dietary research circumstances can vary considerably, the average for the vast majority of groups of ruminant livestock are likely to fall between 5.5 to 6.5 percent. We must caution, however, that little experimental data is available for two-thirds of the world's ruminants in developing countries. Available evidence suggests similar percentage of emissions, but this supposition needs confirmation. More importantly, data is skimpy or unavailable to describe diet consumption, animal weight, and class distribution.

The phase transition of methane caused by pressure change during its seeping up from seepage, revealed by video observation and acoustic reflection data

NASA Astrophysics Data System (ADS)

Aoyama, C.

2017-12-01

Methane plumes often exist in the vicinity sea area where shallow type methane hydrates are extracted and they are observed as images displayed on monitors of multi-beam sonar and echo sounder onboard, where methane hydrates are expected at sea bottom on ROV observation data. The hydrates are generally considered to be generated in shallow depths below the sea floor. In this study, author examined annual amount of methane dissolving into seawater by measuring the amount of plume in order to make a quantification of dissolving methane from seafloor. Measurement procedure is plume exploration using multi-beam and quantitative echo sounder , submerge ROV to gushing point at seafloor , calculate the rising speed of methane plumes and examine the phases by monitoring seeping plumes from seafloor with high-definition camera. Components of seeping plumes were defined as methane hydrate particles based on the result by measuring water temperature. From this procedure, it can be concluded that the minimum rising speed of methane hydrate particles from gushing point is 1.6×10-1(m/s) and the maximum of 2.0×10-1(m/s) indicating a difference of more than ten times the gaseous theoretical value of 2.74(m/s). This speed is theoretically closer to the solid speed of the material with physical property similar to hydrates, which is 3.05×10-1 (m/s). Therefore, it can be determined that those particles are in the solid state, immediately above seafloor. To measure the amount of plumes seeping from gushing points funnel-shaped instruments with 20cm diameter opening were used to collect methane plumes in this sea area. This was performed in three different gushing points. As a result, 300ml of methane plume was collected in 643 seconds. Assuming that gushing points exist evenly in the sea area, the annual amount of methane gas seeping from these points will be 7.7×105m3 /per m2. Result shows a large quantity of methane seeping from seafloor into the water. This data is an important factor when considering carbon cycle and future development the shallow methane hydrate resources.

Effect of dietary fiber on the methanogen community in the hindgut of Lantang gilts.

PubMed

Cao, Z; Liang, J B; Liao, X D; Wright, A D G; Wu, Y B; Yu, B

2016-10-01

The primary objective of this study was to investigate the effect of dietary fiber on methanogenic diversity and community composition in the hindgut of indigenous Chinese Lantang gilts to explain the unexpected findings reported earlier that Lantang gilts fed low-fiber diet (LFD) produced more methane than those fed high-fiber diet (HFD). In total, 12 Lantang gilts (58.7±0.37 kg) were randomly divided into two dietary groups (six replicates (pigs) per group) and fed either LFD (NDF=201.46 g/kg) or HFD (NDF=329.70 g/kg). Wheat bran was the main source of fiber for the LFD, whereas ground rice hull (mixture of rice hull and rice bran) was used for the HFD. Results showed that the methanogens in the hindgut of Lantang gilts belonged to four known species (Methanobrevibacter ruminantium, Methanobrevibacter wolinii, Methanosphaera stadtmanae and Methanobrevibacter smithii), with about 89% of the methanogens belonging to the genus Methanobrevibacter. The 16S ribosomal RNA (rRNA) gene copies of Methanobrevibacter were more than three times higher (P0.05) was observed in 16S rRNA gene copies of Fibrobacter succinogenes between the two dietary groups, and 18S rRNA gene copies of anaerobic fungi in gilts fed LFD were lower than (P<0.05) those fed HFD. To better explain the effect of different fiber source on the methanogen community, a follow-up in vitro fermentation using a factorial design comprised of two inocula (prepared from hindgut content of gilts fed two diets differing in their dietary fiber)×four substrates (LFD, HFD, wheat bran, ground rice hull) was conducted. Results of the in vitro fermentation confirmed that the predominant methanogens belonged to the genus of Methanobrevibacter, and about 23% methanogens was found to be distantly related (90%) to Thermogymnomonas acidicola. In vitro fermentation also seems to suggest that fiber source did change the methanogens community. Although the density of Methanobrevibacter species was positively correlated with CH4 production in both in vivo (P<0.01, r=0.737) and in vitro trials (P<0.05, r=0.854), which could partly explain the higher methane production from gilts fed LFD compared with those in the HFD group. Further investigation is needed to explain how the rice hull affected the methanogens and inhibited CH4 emission from gilts fed HFD.

40 CFR Table Hh-4 to Subpart Hh of... - Landfill Methane Oxidation Fractions

Code of Federal Regulations, 2014 CFR

2014-07-01

... gas sent off-site). If a single monitoring location is used to monitor volumetric flow and CH4... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Landfill Methane Oxidation Fractions... (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Municipal Solid Waste Landfills Pt...

Co-digestion of sewage sludge and sterilized solid slaughterhouse waste: methane production efficiency and process limitations.

PubMed

Pitk, Peep; Kaparaju, Prasad; Palatsi, Jordi; Affes, Rim; Vilu, Raivo

2013-04-01

The rendering product of Category 2 and 3 Animal By-Products is known as sterilized mass (SM) and it is mainly composed of fat and proteins, making it interesting substrate for anaerobic digestion. Batch and semi-continuous laboratory experiments were carried out to investigate the effect of SM addition in co-digestion with sewage sludge on methane production and possible process limitations. Results showed that SM addition in the feed mixture up to 5% (w/w), corresponding to 68.1% of the organic loading, increased methane production 5.7 times, without any indication of process inhibition. Further increase of SM addition at 7.5% (w/w) caused methane production decrease and volatile solids removal reduction, that was mainly related to remarkably increased free ammonia concentration in the digester of 596.5±68.6 gNH3 L(-1). Sterilized mass addition of 10% (w/w) caused intensive foaming, LCFA accumulation of 9172±701.2 mgCOD-LCFA g(-1) sample and termination of the experiment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparison of solid-state to liquid anaerobic digestion of lignocellulosic feedstocks for biogas production.

PubMed

Brown, Dan; Shi, Jian; Li, Yebo

2012-11-01

Lignocellulosic biomass feedstocks (switchgrass, corn stover, wheat straw, yard waste, leaves, waste paper, maple, and pine) were evaluated for methane production under liquid anaerobic digestion (L-AD) and solid-state anaerobic digestion (SS-AD). No significant difference in methane yield between L-AD and SS-AD, except for waste paper and pine, were found. However, the volumetric productivity was 2- to 7-fold greater in the SS-AD system compared with the L-AD system, except for paper. Methane yields from corn stover, wheat straw, and switchgrass were 2-5 times higher than those from yard waste, maple, and pine biomass. Waste paper had a methane yield of only 15 L/kg VS caused by souring during SS-AD due to organic overloading. Pine also had very low biogas yield of 17 L/kg VS, indicating the need for pretreatment prior to SS-AD. The findings of this study can guide future studies to improve the efficiency and stability of SS-AD of lignocellulosic biomass. Copyright © 2012 Elsevier Ltd. All rights reserved.

CH4 emission and recovery from municipal solid waste in China.

PubMed

Xu, Xin-Hua; Yang, Yue-Ping; Wang, Da-Hui

2003-01-01

Methane ( CH4) is an important greenhouse gas and a major environmental pollutant, second only to carbon dioxide (CO2) in its contribution to potential global warming. In many cases, methane emission from landfills otherwise emitted to the atmosphere can be removed and utilized, or significantly reduced in quantity by using coat-effective management methods. The gas can also be used as a residential, commercial, or industrial fuel. Therefore, emission reduction strategies have the potential to become low cost, or even profitable. The annual growth rate of Municipal Solid Waste (MSW) output in China is 6.24%, with the highest levels found in South China, Southwest China and East China. Cities and towns are developing quickly in these regions. MSW output was only 76.36 Mt in 1991 and increased to 109.82 Mt in 1997, registering an average increase of 43.8% . In China, methane emission from landfills also increased from 5.88 Mt in 1991 to 8.46 Mt in 1997; so the recovery of methane from landfills is a profitable project.

Weak interactions between water and clathrate-forming gases at low pressures

DOE PAGES

Thürmer, Konrad; Yuan, Chunqing; Kimmel, Greg A.; ...

2015-07-17

Using scanning probe microscopy and temperature programed desorption we examined the interaction between water and two common clathrate-forming gases, methane and isobutane, at low temperature and low pressure. Water co-deposited with up to 10 –1 mbar methane or 10 –5 mbar isobutane at 140 K onto a Pt(111) substrate yielded pure crystalline ice, i.e., the exposure to up to ~ 10 7 gas molecules for each deposited water molecule did not have any detectable effect on the growing films. Exposing metastable, less than 2 molecular layers thick, water films to 10 –5 mbar methane does not alter their morphology, suggestingmore » that the presence of the Pt(111) surface is not a strong driver for hydrate formation. This weak water–gas interaction at low pressures is supported by our thermal desorption measurements from amorphous solid water and crystalline ice where 1 ML of methane desorbs near ~ 43 K and isobutane desorbs near ~ 100 K. As a result, similar desorption temperatures were observed for desorption from amorphous solid water.« less

Seasonal variation in methane emission from stored slurry and solid manures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husted, S.

1994-05-01

Methane (CH{sub 4}) is an important greenhouse gas and recent inventories have suggested that livestock manure makes a significant contribution to global CH{sub 4} emissions. The emission of CH{sub 4} from stored pig slurry, cattle slurry, pig solid manure, and cattle solid manure was followed during a 1-yr period. Methane emission was determined by dynamic chambers. Emission rates followed a ln-normal distribution for all four manures, Indicating large spatial and seasonal variation& Monthly geometric means for pig slurry, cattle slurry, pig solid manure, and cattle solid manure varied from 0.4 to 35.8, 0.0 to 34.5, 0.4 to 142.1, and 0.1more » to 42.7 g CH{sub 4} m{sup -3} d{sup -1}, respectively. For slurries CH{sub 4} emission rates increased significantly with storage temperatures, the Q{sub 10} value ranging from 14 to 5.7 depending on slurry type. The presence of a natural surface crust reduced CH{sub 4} emission from slurry by a factor of 11 to 12. Surface crust effects declined with increasing slurry temperature. Solid manures stored in dungheaps showed significant heat production. Pig solid manure temperatures were maintained at 30 to 60{degrees}C throughout most of the year, while cattle solid manure temperatures were close to ambient levels until late spring, when heat production was initiated. Methanogenesis in solid manure also increased with increasing temperatures. For pig solid manure, CH{sub 4} emission rates peaked at 35 to 45{degrees}C. No distinct temperature optimum could be detected for cattle solid manure, however, temperatures rarely exceeded 45{degrees}C. The Q{sub 10} values for dungheaps ranged from 2.7 to 10.3 depending on-manure type and Q{sub 10} temperature interval. Annual CH{sub 4} emissions from pig slurry, cattle slurry, pig solid manure, and cattle solid manure were estimated at 8.9, 15.5, 27.3, and 5.3 kg animal{sup -1} yr{sup -1}, respectively. 27 refs., 6 figs., 2 tabs.« less

Effects of bacterial direct-fed microbials on ruminal characteristics, methane emission, and milk fatty acid composition in cows fed high- or low-starch diets.

PubMed

Philippeau, C; Lettat, A; Martin, C; Silberberg, M; Morgavi, D P; Ferlay, A; Berger, C; Nozière, P

2017-04-01

This study investigated the effects of bacterial direct-fed microbials (DFM) on ruminal fermentation and microbial characteristics, methane (CH 4 ) emission, diet digestibility, and milk fatty acid (FA) composition in dairy cows fed diets formulated to induce different ruminal volatile fatty acid (VFA) profiles. Eight ruminally cannulated dairy cows were divided into 2 groups based on parity, days in milk, milk production, and body weight. Cows in each group were fed either a high-starch (38%, HS) or a low-starch (2%, LS) diet in a 55:45 forage-to-concentrate ratio on a dry matter (DM) basis. For each diet, cows were randomly assigned to 1 of 4 treatments in a Latin square design of (1) control (CON); (2) Propionibacterium P63 (P63); (3) P63 plus Lactobacillus plantarum 115 (P63+Lp); (4) P63 plus Lactobacillus rhamnosus 32 (P63+Lr). Strains of DFM were administered at 10 10 cfu/d. Methane emission (using the sulfur hexafluoride tracer technique), total-tract digestibility, dry matter intake, and milk production and composition were quantified in wk 3. Ruminal fermentation and microbial characteristics were measured in wk 4. Data were analyzed using the mixed procedure of SAS (SAS Institute Inc., Cary, NC). The 2 diets induced different ruminal VFA profiles, with a greater proportion of propionate at the expense of acetate and butyrate for the HS diet. Greater concentrations of total bacteria and selected bacterial species of methanogenic Archaea were reported for the HS diet, whereas the protozoa concentration in HS decreased. For both diets, bacterial DFM supplementation raised ruminal pH (+0.18 pH units, on average) compared with CON. Irrespective of diet, P63+Lp and P63+Lr increased ruminal cellulase activity (3.8-fold, on average) compared with CON, but this effect was not associated with variations in ruminal microbial numbers. Irrespective of diet, no effect of bacterial DFM on ruminal VFA was observed. For the LS diet, supplementing cows with P63+Lr tended to decrease CH 4 emission (26.5%, on average, when expressed per kilogram of milk or 4% fat-corrected milk). Only P63 supplementation to cows fed the HS diet affected the concentration of some milk FA, such as cis isomers of 18:1 and intermediates of ruminal biohydrogenation of polyunsaturated FA. Overall, bacterial DFM could be useful to stabilize ruminal pH. Their effects on CH 4 production mitigation and milk FA profile depended on DFM strain and diet and should be confirmed under a greater variation of dietary conditions. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

[In situ Raman spectroscopic observation of micro-processes of methane hydrate formation and dissociation].

PubMed

Liu, Chang-Ling; Ye, Yu-Guang; Meng, Qing-Guo; Lü, Wan-Jun; Wang, Fei-Fei

2011-06-01

Micro laser Raman spectroscopic technique was used for in situ observation of the micro-processes of methane hydrate formed and decomposed in a high pressure transparent capillary. The changes in clathrate structure of methane hydrate were investigated during these processes. The results show that, during hydrate formation, the Raman peak (2 917 cm(-1)) of methane gas gradually splits into two peaks (2 905 and 2 915 cm(-1)) representing large and small cages, respectively, suggesting that the dissolved methane molecules go into two different chemical environments. In the meantime, the hydrogen bonds interaction is strengthened because water is changing from liquid to solid state gradually. As a result, the O-H stretching vibrations of water shift to lower wavenumber. During the decomposition process of methane hydrates, the Raman peaks of the methane molecules both in the large and small cages gradually clear up, and finally turn into a single peak of methane gas. The experimental results show that laser Raman spectroscopy can accurately demonstrate some relevant information of hydrate crystal structure changes during the formation and dissociation processes of methane hydrate.

The effect of diet manipulation on nitrous oxide and methane emissions from manure application to incubated grassland soils

NASA Astrophysics Data System (ADS)

Cardenas, L. M.; Chadwick, D.; Scholefield, D.; Fychan, R.; Marley, C. L.; Jones, R.; Bol, R.; Well, R.; Vallejo, A.

Changes to agricultural management, particularly of the nitrogen (N) input to farms, have great potential for mitigating emissions of N containing gases, especially the greenhouse gas nitrous oxide (N 2O). Manipulating diets fed to livestock is a potential method for controlling N excretion and emissions of greenhouse gases (GHG's) to the atmosphere. We selected three slurries derived from sheep that had been fed, either ensiled ryegrass ( Lolium hybridicum), lucerne ( Medicago sativa) or kale ( Brassica oleracea) and applied them to a grassland soil from the UK in a laboratory experiment using a special He/O 2 atmosphere incubation facility. The resulting fluxes of N 2O, CH 4 and N 2 were measured, with the largest total N fluxes generated by the ryegrass slurry treatment (14.23 ryegrass, 10.84 lucerne, 13.88 kale and 4.40 kg N ha -1 from the control). Methane was emitted only from the ryegrass slurry treatment. The isotopomer signatures for N 2O in the control and lucerne slurry treatments indicated that denitrification was the main process responsible for N 2O emissions.

Thermophilic co-digestion feasibility of distillers grains and swine manure: effect of C/N ratio and organic loading rate during high solid anaerobic digestion (HSAD).

PubMed

Sensai, P; Thangamani, A; Visvanathan, C

2014-01-01

Anaerobic co-digestion of high solids containing distillers grains and swine manure (total solids, 27 +/- 2% and 18 +/- 2%, respectively) was evaluated in this study to assess the effect of C/N ratio and organic loading rate (OLR). Feed mixture was balanced to achieve a C/N ratio of 30/1 by mixing distillers grains and swine manure. Pilot-scale co-digestion of distillers grains and swine manure was carried out under thermophilic conditions in the continuous mode for seven different OLRs from R1 to R7 (3.5, 5, 6, 8, 10, 12 and 14 kg VS/m3 day) under high solid anaerobic digestion. The methane yield and volatile solid (VS) removal were consistent; ranging from 0.33 to 0.34 m3CH4/kg VS day and 50-53%, respectively, until OLR 8 kg VS/m3 day. After which methane yield and VS removal significantly decreased to 0.26 m3 CH4/kg VS day and 42%, respectively, when OLR was increased to 14 kg VS/m3 day. However, during operation, at OLR of 10 kg VS/m3 day, the methane yield and VS removal increased after the 19th day to 0.33 m3 CH4/kg VS day and 46%, respectively, indicating that a longer acclimatization period is required by methanogens at a higher loading rate.

Improved Design of Anaerobic Digesters for Household Biogas Production in Indonesia: One Cow, One Digester, and One Hour of Cooking per Day

PubMed Central

Usack, Joseph G.; Wiratni, Wiratni; Angenent, Largus T.

2014-01-01

A government-sponsored initiative in Indonesia to design and implement low-cost anaerobic digestion systems resulted in 21 full-scale systems with the aim to satisfy the cooking fuel demands of rural households owning at least one cow. The full-scale design consisted of a 0.3 m diameter PVC pipe, which was operated as a conventional plug-flow system. The system generated enough methane to power a cooking stove for ∼1 h. However, eventual clogging from solids accumulation inside the bioreactor proved to be a major drawback. Here, we improved the digester configuration to remedy clogging while maintaining system performance. Controlled experiments were performed using four 9-L laboratory-scale digesters operated at a temperature of 27 ± 1°C, a volatile solids loading rate of 2.0 g VS·L−1 ·day−1, and a 21-day hydraulic retention time. Two of the digesters were replicates of the original design (control digesters), while the other two digesters included internal mixing or effluent recycle (experimental digesters). The performance of each digester was compared based on methane yields, VS removal efficiencies, and steady-state solids concentrations during an operating period of 311 days. Statistical analyses revealed that internal mixing and effluent recycling resulted in reduced solids accumulation compared to the controls without diminishing methane yields or solids removal efficiencies. PMID:24715809

Body weight loss, effective satiation and absence of homeostatic neuropeptide compensation in male Sprague Dawley rats schedule fed a protein crosslinked diet.

PubMed

Cassie, Nikki; Anderson, Richard L; Wilson, Dana; Pawsey, Anne; Mercer, Julian G; Barrett, Perry

2017-10-01

Food structure contributes to the induction of satiation and the maintenance of satiety following intake of a meal. There is evidence from human studies that protein-crosslinking of a milk-protein based meal may enhance satiety, but the mechanism underpinning this effect is unknown. We investigated whether a rat model would respond in a similar manner and might provide mechanistic insight into enhanced satiety by structural modification of a food source. Rats were schedule fed a modified AIN-93M based diet in a liquid form or protein-crosslinked to produce a soft-solid form. This was compared to a modified AIN-93M solid diet. Average daily caloric intake was in the order solid > liquid > crosslinked. Body composition was unaltered in the solid group, but there was a loss of fat in the liquid group and a loss of lean and fat tissue in the crosslinked group. Compared to rats fed a solid diet, acute responses in circulating GLP-1, leptin and insulin were eliminated or attenuated in rats fed a liquid or crosslinked diet. Quantification of homeostatic neuropeptide expression in the hypothalamus showed elevated levels of Npy and Agrp in rats fed the liquid diet. Measurement of food intake after a scheduled meal indicated that reduced energy intake of liquid and crosslinked diets is not due to enhancement of satiety. When continuously available ad-libitum, rats fed a liquid diet showed reduced weight gain despite greater 24 h caloric intake. During the dark phase, caloric intake was reduced, but compensated for during the light phase. We conclude that structural modification from a liquid to a solidified state is beneficial for satiation, with less of a detrimental effect on metabolic parameters and homeostatic neuropeptides. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transport Reactor Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berry, D.A.; Shoemaker, S.A.

1996-12-31

The Morgantown Energy Technology Center (METC) is currently evaluating hot gas desulfurization (HGD)in its on-site transport reactor facility (TRF). This facility was originally constructed in the early 1980s to explore advanced gasification processes with an entrained reactor, and has recently been modified to incorporate a transport riser reactor. The TRF supports Integrated Gasification Combined Cycle (IGCC) power systems, one of METC`s advanced power generation systems. The HGD subsystem is a key developmental item in reducing the cost and increasing the efficiency of the IGCC concept. The TRF is a unique facility with high-temperature, high-pressure, and multiple reactant gas composition capability.more » The TRF can be configured for reacting a single flow pass of gas and solids using a variety of gases. The gas input system allows six different gas inputs to be mixed and heated before entering the reaction zones. Current configurations allow the use of air, carbon dioxide, carbon monoxide, hydrogen, hydrogen sulfide, methane, nitrogen, oxygen, steam, or any mixture of these gases. Construction plans include the addition of a coal gas input line. This line will bring hot coal gas from the existing Fluidized-Bed Gasifier (FBG) via the Modular Gas Cleanup Rig (MGCR) after filtering out particulates with ceramic candle filters. Solids can be fed either by a rotary pocket feeder or a screw feeder. Particle sizes may range from 70 to 150 micrometers. Both feeders have a hopper that can hold enough solid for fairly lengthy tests at the higher feed rates, thus eliminating the need for lockhopper transfers during operation.« less

Estimating national landfill methane emissions: an application of the 2006 Intergovernmental Panel on Climate Change Waste Model in Panama.

PubMed

Weitz, Melissa; Coburn, Jeffrey B; Salinas, Edgar

2008-05-01

This paper estimates national methane emissions from solid waste disposal sites in Panama over the time period 1990-2020 using both the 2006 Intergovernmental Panel on Climate Change (IPCC) Waste Model spreadsheet and the default emissions estimate approach presented in the 1996 IPCC Good Practice Guidelines. The IPCC Waste Model has the ability to calculate emissions from a variety of solid waste disposal site types, taking into account country- or region-specific waste composition and climate information, and can be used with a limited amount of data. Countries with detailed data can also run the model with country-specific values. The paper discusses methane emissions from solid waste disposal; explains the differences between the two methodologies in terms of data needs, assumptions, and results; describes solid waste disposal circumstances in Panama; and presents the results of this analysis. It also demonstrates the Waste Model's ability to incorporate landfill gas recovery data and to make projections. The former default method methane emissions estimates are 25 Gg in 1994, and range from 23.1 Gg in 1990 to a projected 37.5 Gg in 2020. The Waste Model estimates are 26.7 Gg in 1994, ranging from 24.6 Gg in 1990 to 41.6 Gg in 2020. Emissions estimates for Panama produced by the new model were, on average, 8% higher than estimates produced by the former default methodology. The increased estimate can be attributed to the inclusion of all solid waste disposal in Panama (as opposed to only disposal in managed landfills), but the increase was offset somewhat by the different default factors and regional waste values between the 1996 and 2006 IPCC guidelines, and the use of the first-order decay model with a time delay for waste degradation in the IPCC Waste Model.

The potential of biogas production from municipal solid waste in a tropical climate.

PubMed

Getahun, Tadesse; Gebrehiwot, Mulat; Ambelu, Argaw; Van Gerven, Tom; Van der Bruggen, Bart

2014-07-01

The objective of this study was to estimate the potential of organic municipal solid waste generated in an urban setting in a tropical climate to produce biogas. Five different categories of wastes were considered: fruit waste, food waste, yard waste, paper waste, and mixed waste. These fractions were assessed for their efficiency for biogas production in a laboratory-scale batch digester for a total period of 8 weeks at a temperature of 15-30 °C. During this period, fruit waste, food waste, yard waste, paper waste, and mixed waste were observed to produce 0.15, 0.17, 0.10, 0.08, and 0.15 m(3) of biogas per kilogram of volatile solids, respectively. The biogas produced and caloric value of each feedstock was in the range of 1.25 × 10(-3) m(3) (17 kWh)/cap/day (paper waste) to 15 × 10(-3) m(3) (170 kWh)/cap/day (mixed waste). Paper waste produced the least (<1×10(-3)(<17.8 kWh)/cap/day), and mixed waste produced the highest methane yield (10 × 10(-3) m(3) (178 kWh)/cap/day). Thus, mixed waste was found to be more efficient than other feedstocks for biogas and methane production; this was mainly related to the better C/N ratio in mixed waste. Taking the total waste production in Jimma into account, the total mixed organic solid waste could produce 865 × 10(3) m(3) (5.4 m(3)/capita) of biogas or 537 × 10(3) m(3) (3.4 m(3)/capita) of methane per year. The total caloric value of methane production potential from mixed organic municipal solid waste was many times higher than the total energy requirement of the area.

Kinetic study of dry anaerobic co-digestion of food waste and cardboard for methane production.

PubMed

Capson-Tojo, Gabriel; Rouez, Maxime; Crest, Marion; Trably, Eric; Steyer, Jean-Philippe; Bernet, Nicolas; Delgenès, Jean-Philippe; Escudié, Renaud

2017-11-01

Dry anaerobic digestion is a promising option for food waste treatment and valorization. However, accumulation of ammonia and volatile fatty acids often occurs, leading to inefficient processes and digestion failure. Co-digestion with cardboard may be a solution to overcome this problem. The effect of the initial substrate to inoculum ratio (0.25 to 1gVS·gVS -1 ) and the initial total solids contents (20-30%) on the kinetics and performance of dry food waste mono-digestion and co-digestion with cardboard was investigated in batch tests. All the conditions produced methane efficiently (71-93% of the biochemical methane potential). However, due to lack of methanogenic activity, volatile fatty acids accumulated at the beginning of the digestion and lag phases in the methane production were observed. At increasing substrate to inoculum ratios, the initial acid accumulation was more pronounced and lower cumulative methane yields were obtained. Higher amounts of soluble organic matter remained undegraded at higher substrate loads. Although causing slightly longer lag phases, high initial total solids contents did not jeopardize the methane yields. Cardboard addition reduced acid accumulation and the decline in the yields at increasing substrate loads. However, cardboard addition also caused higher concentrations of propionic acid, which appeared as the most last acid to be degraded. Nevertheless, dry co-digestion of food waste and cardboard in urban areas is demonstrated asan interesting feasible valorization option. Copyright © 2017 Elsevier Ltd. All rights reserved.

ELECTROCHEMISTRY AND ON-CELL REFORMATION MODELING FOR SOLID OXIDE FUEL CELL STACKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Recknagle, Kurtis P.; Jarboe, Daniel T.; Johnson, Kenneth I.

2007-01-16

ABSTRACT Providing adequate and efficient cooling schemes for solid-oxide-fuel-cell (SOFC) stacks continues to be a challenge coincident with the development of larger, more powerful stacks. The endothermic steam-methane reformation reaction can provide cooling and improved system efficiency when performed directly on the electrochemically active anode. Rapid kinetics of the endothermic reaction typically causes a localized temperature depression on the anode near the fuel inlet. It is desirable to extend the endothermic effect over more of the cell area and mitigate the associated differences in temperature on the cell to alleviate subsequent thermal stresses. In this study, modeling tools validated formore » the prediction of fuel use, on-cell methane reforming, and the distribution of temperature within SOFC stacks, are employed to provide direction for modifying the catalytic activity of anode materials to control the methane conversion rate. Improvements in thermal management that can be achieved through on-cell reforming is predicted and discussed. Two operating scenarios are considered: one in which the methane fuel is fully pre-reformed, and another in which a substantial percentage of the methane is reformed on-cell. For the latter, a range of catalytic activity is considered and the predicted thermal effects on the cell are presented. Simulations of the cell electrochemical and thermal performance with and without on-cell reforming, including structural analyses, show a substantial decrease in thermal stresses for an on-cell reforming case with slowed methane conversion.« less

Replacing corn silage with different forage millet silage cultivars: effects on milk yield, nutrient digestion, and ruminal fermentation of lactating dairy cows.

PubMed

Brunette, T; Baurhoo, B; Mustafa, A F

2014-10-01

This study investigated the effects of dietary replacement of corn silage (CS) with 2 cultivars of forage millet silages [i.e., regular millet (RM) and sweet millet (SM)] on milk production, apparent total-tract digestibility, and ruminal fermentation characteristics of dairy cows. Fifteen lactating Holstein cows were used in a replicated 3 × 3 Latin square experiment and fed (ad libitum) a high-forage total mixed ration (68:32 forage:concentrate ratio). Dietary treatments included CS (control), RM, and SM diets. Experimental silages constituted 37% of each diet DM. Three ruminally fistulated cows were used to determine the effect of dietary treatments on ruminal fermentation and total-tract nutrient utilization. Relative to CS, RM and SM silages contained 36% more crude protein, 66% more neutral detergent fiber (NDF), and 88% more acid detergent fiber. Cows fed CS consumed more dry matter (DM; 24.4 vs. 22.7 kg/d) and starch (5.7 vs. 3.7 kg/d), but less NDF (7.9 vs. 8.7 kg/d) than cows fed RM or SM. However, DM, starch and NDF intakes were not different between forage millet silage types. Feeding RM relative to CS reduced milk yield (32.7 vs. 35.2 kg/d), energy-corrected milk (35.8 vs. 38.0 kg/d) and SCM (32.7 vs. 35.3 kg/d). However, cows fed SM had similar milk, energy-corrected milk, and solids-corrected milk yields than cows fed CS or RM. Milk efficiency was not affected by dietary treatments. Milk protein concentration was greatest for cows fed CS, intermediate for cows fed SM, and lowest for cows fed RM. Milk concentration of solids-not-fat was lesser, whereas milk urea nitrogen was greater for cows fed RM than for those fed CS. However, millet silage type had no effect on milk solids-not-fat and milk urea nitrogen levels. Concentrations of milk fat, lactose and total solids were not affected by silage type. Ruminal pH and ruminal NH3-N were greater for cows fed RM and SM than for cows fed CS. Total-tract digestibility of DM (average=67.9%), NDF (average=53.9%), crude protein (average=63.3%), and gross energy (average=67.9%) were not influenced by dietary treatments. It was concluded that cows fed CS performed better than those fed RM or SM likely due to the higher starch and lower NDF intakes. However, no major differences were noted between the 2 forage millet silage cultivars. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Ultrasound pretreatment of filamentous algal biomass for enhanced biogas production.

PubMed

Lee, Kwanyong; Chantrasakdakul, Phrompol; Kim, Daegi; Kong, Mingeun; Park, Ki Young

2014-06-01

The filamentous alga Hydrodictyon reticulatum harvested from a bench-scale wastewater treatment pond was used to evaluate biogas production after ultrasound pretreatment. The effects of ultrasound pretreatment at a range of 10-5000 J/mL were tested with harvested H. reticulatum. Cell disruption by ultrasound was successful and showed a higher degree of disintegration at a higher applied energy. The range of 10-5000 J/mL ultrasound was able to disintegrated H. reticulatum and the soluble COD was increased from 250 mg/L to 1000 mg/L at 2500 J/mL. The disintegrated algal biomass was digested for biogas production in batch experiments. Both cumulative gas generation and volatile solids reduction data were obtained during the digestion. Cell disintegration due to ultrasound pretreatment increased the specific biogas production and degradation rates. Using the ultrasound approach, the specific methane production at a dose of 40 J/mL increased up to 384 mL/g-VS fed that was 2.3 times higher than the untreated sample. For disintegrated samples, the volatile solids reduction was greater with increased energy input, and the degradation increased slightly to 67% at a dose of 50 J/mL. The results also indicate that disintegration of the algal cells is the essential step for efficient anaerobic digestion of algal biomass. Copyright © 2013 Elsevier Ltd. All rights reserved.

Experimental Study on Properties of Methane Diffusion of Coal Block under Triaxial Compressive Stress

PubMed Central

Zhao, Hong-Bao

2014-01-01

Taking the standard size coal block samples defined by ISRM as research objects, both properties of methane diffusion of coal block under triaxial compressive stress and characteristic influences caused by methane pressure were systematically studied with thermo-fluid-solid coupling with triaxial servocontrolled seepage equipment of methane-containing coal. The result shows the methane diffusion property of coal block under triaxial compressive stress was shown in four-stage as follow, first is sharply reduce stage, second is hyperbolic reduce stage, third is close to a fixed value stage, fourth stage is 0. There is a special point making the reduced rate of characteristic curve of methane diffusion speed become sharply small; the influences of shape of methane diffusion speed characteristic curve caused by methane pressure are not obvious, which only is shown in numerical size of methane diffusion speed. Test time was extended required by appear of the special point makes the reduce rate of methane diffusion speed become sharply small. The fitting four-phase relation of methane diffusion of coal block under triaxial compressive stress was obtained, and the idea is proposed that influences of the fitting four-phase relation caused by methane pressure were only shown in value of fitting parameters. PMID:25531000

Effect of Increasing Total Solids Contents on Anaerobic Digestion of Food Waste under Mesophilic Conditions: Performance and Microbial Characteristics Analysis

PubMed Central

Jin, Jingwei; Dai, Xiaohu

2014-01-01

The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies. PMID:25051352

Effect of increasing total solids contents on anaerobic digestion of food waste under mesophilic conditions: performance and microbial characteristics analysis.

PubMed

Yi, Jing; Dong, Bin; Jin, Jingwei; Dai, Xiaohu

2014-01-01

The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies.

Combined anaerobic/aerobic digestion: effect of aerobic retention time on nitrogen and solids removal.

PubMed

Kim, Jongmin; Novak, John T

2011-09-01

A combined anaerobic/aerobic sludge digestion system was studied to determine the effect of aerobic solids retention time (SRT) on its solids and nitrogen removal efficiencies. After the anaerobic digester reached steady state, effluent from the anaerobic digester was fed to aerobic digesters that were operated at 2- to 5-day SRTs. The anaerobic system was fed with a mixture of primary and secondary sludge from a local municipal wastewater treatment plant. Both systems were fed once per a day. The aerobic reactor was continuously aerated with ambient air, maintaining dissolved oxygen level at 1.1 +/- 0.3 mg/L. At a 4-day or longer SRT, more than 11% additional volatile solids and 90% or greater ammonia were removed in the aerobic digester, while 32.8 mg-N/L or more nitrite/nitrate also was measured. Most total Kjeldahl nitrogen removal was via ammonia removal, while little organic nitrogen was removed in the aerobic digester.

The use of direct-fed microbials for mitigation of ruminant methane emissions: a review.

PubMed

Jeyanathan, J; Martin, C; Morgavi, D P

2014-02-01

Concerns about the environmental effect and the economic burden of methane (CH4) emissions from ruminants are driving the search for ways to mitigate rumen methanogenesis. The use of direct-fed microbials (DFM) is one possible option to decrease CH4 emission from ruminants. Direct-fed microbials are already used in ruminants mainly to increase productivity and to improve health, and are readily accepted by producers and consumers alike. However, studies on the use of DFM as rumen CH4 mitigants are scarce. A few studies using Saccharomyces cerevisiae have shown a CH4-decreasing effect but, to date, there has not been a systematic exploration of DFM as modulators of rumen methanogenesis. In this review, we explored biochemical pathways competing with methanogenesis that, potentially, could be modulated by the use of DFM. Pathways involving the redirection of H2 away from methanogenesis and pathways producing less H2 during feed fermentation are the preferred options. Propionate formation is an example of the latter option that in addition to decrease CH4 formation increases the retention of energy from the diet. Homoacetogenesis is a pathway using H2 to produce acetate, however up to now no acetogen has been shown to efficiently compete with methanogens in the rumen. Nitrate and sulphate reduction are pathways competing with methanogenesis, but the availability of these substances in the rumen is limited. Although there were studies using nitrate and sulphate as chemical additives, use of DFM for improving these processes and decrease the accumulation of toxic metabolites needs to be explored more. There are some other pathways such as methanotrophy and capnophily or modes of action such as inhibition of methanogens that theoretically could be provided by DFM and affect methanogenesis. We conclude that DFM is a promising alternative for rumen methane mitigation that should be further explored for their practical usage.

Methane yield enhancement via electroporation of organic waste.

PubMed

Safavi, Seyedeh Masoumeh; Unnthorsson, Runar

2017-08-01

An experimental study with pulsed electric field (PEF) pre-treatment was conducted to investigate its effect on methane production. PEF pre-treatment converts organic solids into soluble and colloidal forms, increasing bioavailability for anaerobic microorganisms participating in methane generation process. The substrates tested were landfill leachate and fruit/vegetable. Three treatment intensities of 15, 30, and 50kWh/m 3 were applied to investigate the influence of pre-treatment on methane production via biochemical methane potential test. Threshold treatment intensity was found to be around 30kWh/m 3 for landfill leachate beyond which the methane production enhanced linearly with increase in intensity. Methane production of the landfill leachate significantly increased up to 44% with the highest intensity. The result of pulsed electric field pre-treatment on fruit/vegetable showed that 15kWh/m 3 was the intensity by which the highest amount of methane (up to 7%) was achieved. Beyond this intensity, the methane production decreased. Chemical oxygen demand removals were increased up to 100% for landfill leachate and 17% for fruit/vegetable, compared to the untreated slurries. Results indicate that the treatment intensity has a significant effect on the methane production and biosolid removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

Methane Hydrate in Confined Spaces: An Alternative Storage System.

PubMed

Borchardt, Lars; Casco, Mirian Elizabeth; Silvestre-Albero, Joaquin

2018-06-05

Methane hydrate inheres the great potential to be a nature-inspired alternative for chemical energy storage, as it allows to store large amounts of methane in a dense solid phase. The embedment of methane hydrate in the confined environment of porous materials can be capitalized for potential applications as its physicochemical properties, such as the formation kinetics or pressure and temperature stability, are significantly changed compared to the bulk system. We review this topic from a materials scientific perspective by considering porous carbons, silica, clays, zeolites, and polymers as host structures for methane hydrate formation. We discuss the contribution of advanced characterization techniques and theoretical simulations towards the elucidation of the methane hydrate formation and dissociation process within the confined space. We outline the scientific challenges this system is currently facing and look on possible future applications for this technology. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of thermal loading on a methane injector at high pressure and temperature

NASA Technical Reports Server (NTRS)

Harvin, Stephen F.

1990-01-01

Experimental and numerical analyses are conducted to determine the surface temperature on a methane fuel injector used to produce a high enthalpy test stream for a combustion-fed subscale wind tunnel facility. It was found that the ratio of the methane fuel injection velocity to the air stream velocity is a significant factor in the production of high injector surface temperatures which lead to rapid deterioration of the fuel injector structure. The numerical code utilized for the computational analysis was found to be representative of the experimentally measured data since the experimental trends were reproduced by the numerical simulation. The quantitative accuracy of the numerical predictions could not be assessed from the data gathered because of the difficulty of making a noninterfering injector surface temperature measurement. The numerical code can be used for parametric evaluation of combustor parameters and thus will serve as an important tool in the design of such fuel injector systems.

Biomass adaptation over anaerobic co-digestion of sewage sludge and trapped grease waste.

PubMed

Silvestre, G; Rodríguez-Abalde, A; Fernández, B; Flotats, X; Bonmatí, A

2011-07-01

The feasibility of sewage sludge co-digestion using intermediate waste generated inside a wastewater treatment plant, i.e. trapped grease waste from the dissolved air flotation unit, has been assessed in a continuous stirred lab reactor operating at 35°C with a hydraulic retention time of 20 days. Three different periods of co-digestion were carried out as the grease waste dose was increased. When the grease waste addition was 23% of the volatile solids fed (organic loading rate 3.0 kg(COD)m(-3)d(-1)), an increase in methane yield of 138% was reported. Specific activity tests suggested that anaerobic biomass had adapted to the co-substrate. The adapted inoculum showed higher acetoclastic methanogenic and β-oxidation synthrophic acetogenic activities but lower hydrogenotrophic methanogenic activity. The results indicate that a slow increase in the grease waste dose could be a strategy that favours biomass acclimation to fat-rich co-substrate, increases long chain fatty acid degradation and reduces the latter's inhibitory effect. Copyright © 2011 Elsevier Ltd. All rights reserved.

[Impact of Thermal Treatment on Biogas Production by Anaerobic Digestion of High-solid-content Swine Manure].

PubMed

Hu, Yu-ying; Wu, Jing; Wang, Shi-feng; Cao, Zhi-ping; Wang, Kai-jun; Zuo, Jian-e

2015-08-01

Livestock manure is a kind of waste with high organic content and sanitation risk. In order to investigate the impact of thermal treatment on the anaerobic digestion of high-solid-content swine manure, 70 degrees C thermal treatment was conducted to treat raw manure (solid content 27.6%) without any dilution. The results indicated that thermal treatment could reduce the organic matters and improve the performance of anaerobic digestion. When the thermal treatment time was 1d, 2d, 3d, 4d, the VS removal rates were 15.1%, 15.5%, 17.8% and 20.0%, respectively. The methane production rates (CH4/VSadd) were 284.4, 296.3, 309.2 and 264.4 mL x g(-1), which was enhanced by 49.7%, 55.9%, 62.7% and 39.2%, respectively. The highest methane production rate occurred when the thermal treatment time was 3d. The thermal treatment had an efficient impact on promoting the performance of methane production rate with a suitable energy consumption. On the other hand, thermal treatment could act as pasteurization. This showed that thermal treatment would be of great practical importance.

Determination of biogas generation potential as a renewable energy source from supermarket wastes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alkanok, Gizem; Demirel, Burak, E-mail: burak.demirel@boun.edu.tr; Onay, Turgut T.

2014-01-15

Highlights: • Disposal of supermarket wastes in landfills may contribute to environmental pollution. • High methane yields can be obtained from supermarket wastes by anaerobic co-digestion. • Fruit and vegetable wastes or dairy products wastes could individually be handled by a two-stage anaerobic process. • Buffering capacity, trace metal and C/N ratio are essential for digestion of supermarket wastes. - Abstract: Fruit, vegetable, flower waste (FVFW), dairy products waste (DPW), meat waste (MW) and sugar waste (SW) obtained from a supermarket chain were anaerobically digested, in order to recover methane as a source of renewable energy. Batch mesophilic anaerobic reactorsmore » were run at total solids (TS) ratios of 5%, 8% and 10%. The highest methane yield of 0.44 L CH{sub 4}/g VS{sub added} was obtained from anaerobic digestion of wastes (FVFW + DPW + MW + SW) at 10% TS, with 66.4% of methane (CH{sub 4}) composition in biogas. Anaerobic digestion of mixed wastes at 5% and 8% TS provided slightly lower methane yields of 0.41 and 0.40 L CH{sub 4}/g VS{sub added}, respectively. When the wastes were digested alone without co-substrate addition, the highest methane yield of 0.40 L CH{sub 4}/g VS{sub added} was obtained from FVFW at 5% TS. Generally, although the volatile solids (VS) conversion percentages seemed low during the experiments, higher methane yields could be obtained from anaerobic digestion of supermarket wastes. A suitable carbon/nitrogen (C/N) ratio, proper adjustment of the buffering capacity and the addition of essential trace nutrients (such as Ni) could improve VS conversion and biogas production yields significantly.« less

Recovery of energy and nutrient resources from cattle paunch waste using temperature phased anaerobic digestion.

PubMed

Jensen, Paul D; Mehta, Chirag M; Carney, Chris; Batstone, D J

2016-05-01

Cattle paunch is comprised of partially digested cattle feed, containing mainly grass and grain and is a major waste produced at cattle slaughterhouses contributing 20-30% of organic matter and 40-50% of P waste produced on-site. In this work, Temperature Phased Anaerobic Digestion (TPAD) and struvite crystallization processes were developed at pilot-scale to recover methane energy and nutrients from paunch solid waste. The TPAD plant achieved a maximum sustainable organic loading rate of 1-1.5kgCODm(-3)day(-1) using a feed solids concentration of approximately 3%; this loading rate was limited by plant engineering and not the biology of the process. Organic solids destruction (60%) and methane production (230LCH4kg(-1) VSfed) achieved in the plant were similar to levels predicted from laboratory biochemical methane potential (BMP) testing. Model based analysis identified no significant difference in batch laboratory parameters vs pilot-scale continuous parameters, and no change in speed or extent of degradation. However the TPAD process did result in a degree of process intensification with a high level of solids destruction at an average treatment time of 21days. Results from the pilot plant show that an integrated process enabled resource recovery at 7.8GJ/dry tonne paunch, 1.8kgP/dry tonne paunch and 1.0kgN/dry tonne paunch. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of Ultrasonic Pretreatment on Biomethane Potential of Two-Phase Olive Mill Solid Waste: Kinetic Approach and Process Performance

PubMed Central

Rincón, B.; Bujalance, L.; Fermoso, F. G.; Martín, A.

2014-01-01

The effect of ultrasound (US) pretreatment on two-phase olive mil solid waste (OMSW) composition and subsequent anaerobic biodegradation was evaluated by chemical oxygen demand solubilization and biochemical methane potential (BMP) tests. OMSW was ultrasonically pretreated at a power of 200 W and frequency of 24 kHz for time periods of 20, 40, 60, 90, 120, and 180 minutes, corresponding to specific energies of 11367, 21121, 34072, 51284, 68557, and 106003 kJ/kg total solids, respectively. In order to evaluate the US pretreatment, a low, medium, and high exposure time, that is, 20, 90, and 180 min, were selected for BMP tests. Methane yields of 311 ± 15, 393 ± 14, and 370 ± 20 mL CH4/g VSadded (VS: volatile solids) were obtained for 20, 90, and 180 minutes, respectively, while the untreated OMSW gave 373 ± 4 mL CH4/g VSadded. From a kinetic point of view, the BMP tests showed a first exponential stage and a second sigmoidal stage. In the first stage, the kinetic constant obtained for US pretreated OMSW at 20 minutes was 46% higher than those achieved for the pretreated OMSW at 90 and 180 minutes and 48% higher than that for untreated OMSW. The maximum methane production rate achieved was 12% higher than that obtained for untreated OMSW. PMID:25197705

An advanced carbon reactor subsystem for carbon dioxide reduction

NASA Technical Reports Server (NTRS)

Noyes, Gary P.; Cusick, Robert J.

1986-01-01

An evaluation is presented of the development status of an advanced carbon-reactor subsystem (ACRS) for the production of water and dense, solid carbon from CO2 and hydrogen, as required in physiochemical air revitalization systems for long-duration manned space missions. The ACRS consists of a Sabatier Methanation Reactor (SMR) that reduces CO2 with hydrogen to form methane and water, a gas-liquid separator to remove product water from the methane, and a Carbon Formation Reactor (CFR) to pyrolize methane to carbon and hydrogen; the carbon is recycled to the SMR, while the produce carbon is periodically removed from the CFR. A preprototype ACRS under development for the NASA Space Station is described.

Analysis of Percent On-Cell Reformation of Methane in SOFC Stacks: Thermal, Electrical and Stress Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Recknagle, Kurtis P.; Yokuda, Satoru T.; Jarboe, Daniel T.

2006-04-07

This report summarizes a parametric analysis performed to determine the effect of varying the percent on-cell reformation (OCR) of methane on the thermal and electrical performance for a generic, planar solid oxide fuel cell (SOFC) stack design. OCR of methane can be beneficial to an SOFC stack because the reaction (steam-methane reformation) is endothermic and can remove excess heat generated by the electrochemical reactions directly from the cell. The heat removed is proportional to the amount of methane reformed on the cell. Methane can be partially pre-reformed externally, then supplied to the stack, where rapid reaction kinetics on the anodemore » ensures complete conversion. Thus, the thermal load varies with methane concentration entering the stack, as does the coupled scalar distributions, including the temperature and electrical current density. The endotherm due to the reformation reaction can cause a temperature depression on the anode near the fuel inlet, resulting in large thermal gradients. This effect depends on factors that include methane concentration, local temperature, and stack geometry.« less

Effects of mineral salt supplement on enteric methane emissions, ruminal fermentation and methanogen community of lactating cows.

PubMed

Li, Xiaohua; Liu, Chong; Chen, Yongxing; Shi, Rongguang; Cheng, Zhenhua; Dong, Hongmin

2017-08-01

We evaluated the effects of mineral salt supplement on enteric methane emissions, ruminal fermentation and methanogen community of dairy cows over a whole lactation period. Ten Holstein cows fed a total mixed ration (TMR) diet were randomly allocated into two groups, one supplied with mineral salts as the treatment group and the other as the control group. The methane measurement showed that the ingestion of mineral salts lowered enteric methane emissions significantly (P < 0.05), with an average of 10.5% reduction over the whole lactation period. Ruminal fermentation analysis showed the mineral salt intake could significantly decrease the acetate : propionate ratio (P < 0.05). Real-time PCR assay showed that rumen methanogen abundance significantly reduced in the treatment group (P < 0.05) but was not significantly influenced by mineral salt intake over the whole lactation period. Intergroup methanogen community composition was influenced slightly by mineral salt intake; however, significantly different intragroup profiles were apparent throughout the whole lactation period, according to denaturing gradient gel electrophoresis analysis. In conclusion, these results suggested that the effective mitigation of enteric methane emissions by mineral salt intake could be attributed to decreased density of methanogenic archaea and that fluctuations in methane emission over the lactation period might be related to Methanobrevibacter diversity. © 2016 Japanese Society of Animal Science.

The Optimation of Crude Fiber Content of Diet for Fattening Madura Beef Cattle to Achieve Good A:P Ratio and Low Methane Production

NASA Astrophysics Data System (ADS)

Luthfi, N.; Restitrisnani, V.; Umar, M.

2018-02-01

Abtract. Methane (CH4) is one of the major greenhouse gases being reducted. This study was carried out to determine the optimum of crude fiber needed for fattening Madura beef cattle to achieve low methane production. Twenty-four male madura beef cattles with an average body weight of 206.89 ± 7.82 kg were used in this study. Cattle were fed contained 47.65 - 70.23 % Total Digestible Nutrients (TDN), 9.22 - 13.20% Crude Protein (CP), and 10.25 - 28.53% Crude Fiber (CF). Correlation analysis was used to describe the correlations among crude fiber,Methane, and Acetate:Propionate acid ratio. The result showed that crude fiber (%) had medium possitive correlation with methane and the equation was y = 0.0936x + 5.4853 with determination as much as 33.98%. The Acetate: propionate acid had positive correlation withmethane and the equation was y = 1.1121x + 3.581 with determination as much as 61.64%. Crude fiber (%) had low possitive correlation with A/P ratio and the equation was y = 0.039x + 2.4437 with determination as much as 9.56%. According to the results, it can be concluded that the optimum ofcrude fiberof diet for Madura beef cattle should be 15.38% to obtain A:P ratio of 3 or less and methane production of 6.91 MJ/d.

Modelling global methane emissions from livestock: Biological and nutritional controls. Final Report, 1 July 1989-30 June 1992

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, D.E.

1992-10-01

The available observations of methane production from the literature have been compiled into a ruminant methane data base. This data base includes 400 treatment mean observations of methane losses from cattle and sheep, and minor numbers of measurements from other species. Methane loss varied from 2.0 to 11.6 percent of dietary gross energy. Measurements included describe the many different weights and physiological states of the animals fed and diets ranging from all forage to all concentrate diets or mixtures. An auxiliary spreadsheet lists approximately 1000 individual animal observations. Many important concepts have emerged from our query and analysis of thismore » data set. The majority of the world's cattle, sheep, and goats under normal husbandry circumstances likely produce methane very close to 6 percent of their daily diets gross energy (2 percent of the diet by weight). Although individual animals or losses from specific dietary research circumstances can vary considerably, the average for the vast majority of groups of ruminant livestock are likely to fall between 5.5 to 6.5 percent. We must caution, however, that little experimental data is available for two-thirds of the world's ruminants in developing countries. Available evidence suggests similar percentage of emissions, but this supposition needs confirmation. More importantly, data is skimpy or unavailable to describe diet consumption, animal weight, and class distribution.« less

Reactor performance and energy analysis of solid state anaerobic co-digestion of dairy manure with corn stover and tomato residues.

PubMed

Li, Yangyang; Xu, Fuqing; Li, Yu; Lu, Jiaxin; Li, Shuyan; Shah, Ajay; Zhang, Xuehua; Zhang, Hongyu; Gong, Xiaoyan; Li, Guoxue

2018-03-01

Anaerobic co-digestion is commonly believed to be benefical for biogas production. However, additional of co-substrates may require additional energy inputs and thus affect the overall energy efficiency of the system. In this study, reactor performance and energy analysis of solid state anaerobic digestion (SS-AD) of tomato residues with dairy manure and corn stover were investigated. Different fractions of tomato residues (0, 20, 40, 60, 80 and 100%, based on volatile solid weight (VS)) were co-digested with dairy manure and corn stover at 15% total solids. Energy analysis based on experimental data was conducted for three scenarios: SS-AD of 100% dairy manure, SS-AD of binary mixture (60% dairy manure and 40% corn stover, VS based), and SS-AD of ternary mixture (36% dairy manure, 24% corn stover, and 40% tomato residues, VS based). For each scenario, the energy requirements for individual process components, including feedstock collection and transportation, feedstock pretreatment, biogas plant operation, digestate processing and handling, and the energy production were examined. Results showed that the addition of 20 and 40% tomato residues increased methane yield compared to that of the dairy manure and corn stover mixture, indicating that the co-digestion could balance nutrients and improve the performance of solid-state anaerobic digestion. The energy required for heating substrates had the dominant effect on the total energy consumption. The highest volatile solids (VS) reduction (57.0%), methane yield (379.1 L/kg VS feed ), and net energy production were achieved with the mixture of 24% corn stover, 36% dairy manure, and 40% tomato residues. Thus, the extra energy input for adding tomato residues for co-digestion could be compensated by the increase of methane yield. Copyright © 2017 Elsevier Ltd. All rights reserved.

Title I preliminary engineering for: A. S. E. F. solid waste to methane gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1976-01-01

An assignment to provide preliminary engineering of an Advanced System Experimental Facility for production of methane gas from urban solid waste by anaerobic digestion is documented. The experimental facility will be constructed on a now-existing solid waste shredding and landfill facility in Pompano Beach, Florida. Information is included on: general description of the project; justification of basic need; process design; preliminary drawings; outline specifications; preliminary estimate of cost; and time schedules for design and construction of accomplishment of design and construction. The preliminary cost estimate for the design and construction phases of the experimental program is $2,960,000, based on Dec.more » 1975 and Jan. 1976 costs. A time schedule of eight months to complete the Detailed Design, Equipment Procurement and the Award of Subcontracts is given.« less

Effects of dietary tannin source on performance, feed efficiency, ruminal fermentation, and carcass and non-carcass traits in steers fed a high-grain diet

USDA-ARS?s Scientific Manuscript database

Tannins are polyphenolic secondary plant compounds that have been shown to affect microbial activity to impact fermentation, protein degradation, methane production, and potential to mitigate foodborne pathogens. This study was conducted to examine the effects of source of tannin (condensed, CT, vs....

Methane and carbon at equilibrium in source rocks

PubMed Central

2013-01-01

Methane in source rocks may not exist exclusively as free gas. It could exist in equilibrium with carbon and higher hydrocarbons: CH4 + C < = > Hydrocarbon. Three lines of evidence support this possibility. 1) Shales ingest gas in amounts and selectivities consistent with gas-carbon equilibrium. There is a 50% increase in solid hydrocarbon mass when Fayetteville Shale is exposed to methane (450 psi) under moderate conditions (100°C): Rock-Eval S2 (mg g-1) 8.5 = > 12.5. All light hydrocarbons are ingested, but with high selectivity, consistent with competitive addition to receptor sites in a growing polymer. Mowry Shale ingests butane vigorously from argon, for example, but not from methane under the same conditions. 2) Production data for a well producing from Fayetteville Shale declines along the theoretical curve for withdrawing gas from higher hydrocarbons in equilibrium with carbon. 3) A new general gas-solid equilibrium model accounts for natural gas at thermodynamic equilibrium, and C6-C7 hydrocarbons constrained to invariant compositions. The results make a strong case for methane in equilibrium with carbon and higher hydrocarbons. If correct, the higher hydrocarbons in source rocks are gas reservoirs, raising the possibility of substantially more gas in shales than analytically apparent, and far more gas in shale deposits than currently recognized. PMID:24330266

Kinetics of anaerobic degradation of screened dairy manure by upflow fixed bed digesters: effect of natural zeolite addition.

PubMed

Nikolaeva, S; Sánchez, E; Borja, R; Raposo, F; Colmenarejo, M F; Montalvo, S; Jiménez-Rodríguez, A M

2009-02-01

The effect of the hydraulic retention time (HRT) on the performance of two up-flow anaerobic fixed bed digesters (UFAFBDs) packed with waste tire rubber (D1) and waste tire rubber and zeolite (D2) as micro-organism immobilization supports was studied. It was found that a first-order kinetic model described well the experimental results obtained. The kinetic constants for COD, BOD5, total solids (TS) and volatile solids (VS) removal were determined to be higher in digester D2 than in digester D1 or control. Specifically, they were 0.28 +/- 0.01, 0.32 +/- 0.02, 0.16 +/- 0.01 and 0.24 +/- 0.01 d(- 1) respectively for D1 and 0.33 +/- 0.02, 0.40 +/- 0.02, 0.21 +/- 0.01 and 0.28 +/- 0.01 d(- 1) respectively for D2. This was significant at the 95% confidence level. In addition, the first-order model was also adequate for assessing the effect of the HRT on the removal efficiency and methane production. Maximum methane yield and the first-order constant for methane production were determined and the results obtained were comparable with those obtained by other authors but operating at higher HRTs. Maximum methane yields and the kinetic constant for methane production were 11.1% and 29.4% higher in digester D2 than in D1.

Nutrient utilization, ruminal fermentation, microbial abundances, and milk yield and composition in dairy goats fed diets including tomato and cucumber waste fruits.

PubMed

Romero-Huelva, M; Ramos-Morales, E; Molina-Alcaide, E

2012-10-01

The effects of replacing 35% of cereals-based concentrate with feed blocks (FB) containing waste fruits of tomato, cucumber, or barley grain in diets for lactating goats on nutrient utilization, ruminal fermentation, microbial N flow to the duodenum, milk yield and quality, methane emissions, and abundances of total bacteria and methanogens were studied. Eight Murciano-Granadina goats (39.4 ± 5.39 kg of body weight, mean ± SD) in the middle of the third lactation were used and 4 diets were studied in a replicated 4×4 Latin square experimental design. Diets consisted of alfalfa hay (A) plus concentrate (C) in a 1:1 ratio (diet AC) or diets in which 35% of the concentrate was replaced with FB including wastes of tomato fruit, cucumber, or barley. In each period, 2 goats were randomly assigned to 1 of the dietary treatments. Intakes of FB including tomato, cucumber, and barley were 208 ± 65, 222 ± 52, and 209 ± 83 g of dry matter per animal and day, respectively. The replacement of 35% of concentrate with FB did not compromise nutrient apparent digestibility, total purine derivative urinary excretion, milk yield and composition, and total bacteria and methanogen abundances. Digestible energy and that in methane and urine were higher for AC than for FB-containing diets, whereas the metabolizable energy value was not affected by diet. The inclusion of tomato and cucumber fruits in FB decreased N in urine and CH(4) emissions compared with AC, which is environmentally relevant. However, tomato-based FB decreased microbial N flow in the rumen, whereas goats fed cucumber-based FB had the highest values for this measurement. Moreover, FB containing barley or tomato and cucumber led to lower rumen volatile fatty acid and NH(3)-N concentrations, respectively. Milk from goats fed diets including tomato and cucumber-based FB had higher linoleic, linolenic, and total polyunsaturated fatty acid concentrations than that from goats fed AC. Overall, our study suggests that tomato and cucumber FB could replace 35% of the concentrate in the dairy goat diet, reducing animal feeding cost and methane production, leading to higher polyunsaturated fatty acid proportions in milk, and without compromising nutrient utilization or milk yield. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Anaerobic digestion of grass: the effect of temperature applied during the storage of substrate on the methane production.

PubMed

Míchal, Pavel; Švehla, Pavel; Plachý, Vladimír; Tlustoš, Pavel

2017-07-01

Within this research, biogas production, representation of methane in biogas and volatile solids (VSs) removal efficiency were compared using batch tests performed with the samples of intensively and extensively planted grasses originating from public areas. Before the batch tests, the samples were stored at different temperatures achievable on biogas plants applying trigeneration strategy (-18°C, +3°C, +18°C and +35°C). Specific methane production from intensively planted grasses was relatively high (0.33-0.41 m 3 /kg VS) compared to extensively planted grasses (0.20-0.33 m 3 /kg VS). VSs removal efficiency reached 59.8-68.8% for intensively planted grasses and 34.6-56.5% for extensively planted grasses. Freezing the intensively planted grasses at -18°C proved to be an effective thermal pretreatment leading to high biogas production (0.61 m 3 /kg total solid (TS)), high representation of methane (64.0%) in biogas and good VSs removal efficiency (68.8%). The results of this research suggest that public areas or sport parks seem to be available, cheap and at the same time very effective feedstock for biogas production.

An innovative sewage sludge reduction by using a combined mesophilic anaerobic and thermophilic aerobic process with thermal-alkaline treatment and sludge recirculation.

PubMed

Cho, Hyun Uk; Park, Sang Kyu; Ha, Jeong Hyub; Park, Jong Moon

2013-11-15

Lab-scale High Efficiency Digestion (HED) systems containing a Mesophilic Anaerobic Reactor (MAR), Thermophilic Aerobic Reactor (TAR), liquid/solid separation unit, and thermal-alkaline treatment were developed to evaluate the efficiencies of sludge reduction and methane production. The HED process was divided into three phases to examine the influence of sludge pretreatment and pretreated sludge recirculation using TCOD and VSS reduction, COD solubilization, and methane production. The VSS removal with a solid/liquid separation unit, sludge recirculation, and thermal-alkaline treatment drastically increased up to 95% compared to the feed concentration. In addition, the results of COD solubilization and VSS/TSS showed that the solubilization of cells and organic matters by the thermal-alkaline treatment was highly increased, which was also consistent with the SEM images. In particular, the methane production rate increased 24-fold when the feed sludge and recirculated sludge were pretreated together. Collectively, the HED experiments performed with sludge recirculation and thermal-alkaline treatment demonstrated that the HED systems can be successfully employed for highly efficient sewage sludge reduction and methane gas production. Copyright © 2013 Elsevier Ltd. All rights reserved.

Production waters associated with the Ferron coalbed methane fields, central Utah: Chemical and isotopic composition and volumes

USGS Publications Warehouse

Rice, C.A.

2003-01-01

This study investigated the composition of water co-produced with coalbed methane (CBM) from the Upper Cretaceous Ferron Sandstone Member of the Mancos Shale in east-central Utah to better understand coalbed methane reservoirs. The Ferron coalbed methane play currently has more than 600 wells producing an average of 240 bbl/day/well water. Water samples collected from 28 wellheads in three fields (Buzzards Bench, Drunkards Wash, and Helper State) of the northeast-southwest trending play were analyzed for chemical and stable isotopic composition.Water produced from coalbed methane wells is a Na-Cl-HCO3 type. Water from the Drunkards Wash field has the lowest total dissolved solids (TDS) (6300 mg/l) increasing in value to the southeast and northeast. In the Helper State field, about 6 miles northeast, water has the highest total dissolved solids (43,000 mg/l), and major ion abundance indicates the possible influence of evaporite dissolution or mixing with a saline brine. In the southern Buzzards Bench field, water has variable total dissolved solids that are not correlated with depth or spatial distance. Significant differences in the relative compositions are present between the three fields implying varying origins of solutes and/or different water-rock interactions along multiple flow paths.Stable isotopic values of water from the Ferron range from +0.9??? to -11.4??? ?? 18O and -32??? to -90??? ?? 2H and plot below the global meteoric water line (GMWL) on a line near, but above values of present-day meteoric water. Isotopic values of Ferron water are consistent with modification of meteoric water along a flow path by mixing with an evolved seawater brine and/or interaction with carbonate minerals. Analysis of isotopic values versus chloride (conservative element) and total dissolved solids concentrations indicates that recharge water in the Buzzards Bench area is distinct from recharge water in Drunkards Wash and is about 3 ??C warmer. These variations in isotopes along with compositional variations imply that the Ferron reservoir is heterogeneous and compartmentalized, and that multiple flow paths may exist. ?? 2003 Published by Elsevier B.V. All rights reserved.

BIODEGRADATIVE ANALYSIS OF MUNICIPAL SOLID WASTE IN LABORATORY-SCALE LANDFILLS

EPA Science Inventory

The report gives results of research to characterize the anaerobic biodegradability of the major biodegradable components of municipal solid waste (MSW). Tests were conducted in quadruplicate in 2-L reactors operated to obtain maximum yields. Measured methane (CH4) yields for gra...

High solids fermentation reactor

DOEpatents

Wyman, Charles E.; Grohmann, Karel; Himmel, Michael E.; Richard, Christopher J.

1993-03-02

A fermentation reactor and method for fermentation of materials having greater than about 10% solids. The reactor includes a rotatable shaft along the central axis, the shaft including rods extending outwardly to mix the materials. The reactor and method are useful for anaerobic digestion of municipal solid wastes to produce methane, for production of commodity chemicals from organic materials, and for microbial fermentation processes.

High solids fermentation reactor

DOEpatents

Wyman, Charles E.; Grohmann, Karel; Himmel, Michael E.; Richard, Christopher J.

1993-01-01

A fermentation reactor and method for fermentation of materials having greater than about 10% solids. The reactor includes a rotatable shaft along the central axis, the shaft including rods extending outwardly to mix the materials. The reactor and method are useful for anaerobic digestion of municipal solid wastes to produce methane, for production of commodity chemicals from organic materials, and for microbial fermentation processes.

Shifts in Rumen Fermentation and Microbiota Are Associated with Dissolved Ruminal Hydrogen Concentrations in Lactating Dairy Cows Fed Different Types of Carbohydrates.

PubMed

Wang, Min; Wang, Rong; Xie, Tian Yu; Janssen, Peter H; Sun, Xue Zhao; Beauchemin, Karen A; Tan, Zhi Liang; Gao, Min

2016-09-01

Different carbohydrates ingested greatly influence rumen fermentation and microbiota and gaseous methane emissions. Dissolved hydrogen concentration is related to rumen fermentation and methane production. We tested the hypothesis that carbohydrates ingested greatly alter the rumen environment in dairy cows, and that dissolved hydrogen concentration is associated with these changes in rumen fermentation and microbiota. Twenty-eight lactating Chinese Holstein dairy cows [aged 4-5 y, body weight 480 ± 37 kg (mean ± SD)] were used in a randomized complete block design to investigate effects of 4 diets differing in forage content (45% compared with 35%) and source (rice straw compared with a mixture of rice straw and corn silage) on feed intake, rumen fermentation, and microbial populations. Feed intake (10.7-12.6 kg/d) and fiber degradation (0.584-0.692) greatly differed (P ≤ 0.05) between cows fed the 4 diets, leading to large differences (P ≤ 0.05) in gaseous methane yield (27.2-37.3 g/kg organic matter digested), dissolved hydrogen (0.258-1.64 μmol/L), rumen fermentation products, and microbiota. Ruminal dissolved hydrogen was negatively correlated (r < -0.40; P < 0.05) with molar proportion of acetate, numbers of fungi, abundance of Fibrobacter succinogenes, and methane yield, but positively correlated (r > 0.40; P < 0.05) with molar proportions of propionate and n-butyrate, numbers of methanogens, and abundance of Selenomonas ruminantium and Prevotella spp. Ruminal dissolved hydrogen was positively correlated (r = 0.93; P < 0.001) with Gibbs free energy changes of reactions producing greater acetate and hydrogen, but not correlated with those reactions producing more propionate without hydrogen. Changes in fermentation pathways from acetate toward propionate production and in microbiota from fibrolytic toward amylolytic species were closely associated with ruminal dissolved hydrogen in lactating dairy cows. An unresolved paradox was that greater dissolved hydrogen was associated with greater numbers of methanogens but with lower gaseous methane emissions. © 2016 American Society for Nutrition.

Systematic metabolic engineering of Methylomicrobium alcaliphilum 20Z for 2,3-butanediol production from methane.

PubMed

Nguyen, Anh Duc; Hwang, In Yeub; Lee, Ok Kyung; Kim, Donghyuk; Kalyuzhnaya, Marina G; Mariyana, Rina; Hadiyati, Susila; Kim, Min Sik; Lee, Eun Yeol

2018-04-16

Methane is considered a next-generation feedstock, and methanotrophic cell-based biorefinery is attractive for production of a variety of high-value compounds from methane. In this work, we have metabolically engineered Methylomicrobium alcaliphilum 20Z for 2,3-butanediol (2,3-BDO) production from methane. The engineered strain 20Z/pBudK.p, harboring the 2,3-BDO synthesis gene cluster (budABC) from Klebsiella pneumoniae, accumulated 2,3-BDO in methane-fed shake flask cultures with a titer of 35.66 mg/L. Expression of the most efficient gene cluster was optimized using selection of promoters, translation initiation rates (TIR), and the combination of 2,3-BDO synthesis genes from different sources. A higher 2,3-BDO titer of 57.7 mg/L was measured in the 20Z/pNBM-Re strain with budA of K. pneumoniae and budB of Bacillus subtilis under the control of the Tac promoter. The genome-scale metabolic network reconstruction of M. alcaliphilum 20Z enabled in silico gene knockout predictions using an evolutionary programming method to couple growth and 2,3-BDO production. The ldh, ack, and mdh genes in M. alcaliphilum 20Z were identified as potential knockout targets. Pursuing these targets, a triple-mutant strain ∆ldh ∆ack ∆mdh was constructed, resulting in a further increase of the 2,3-BDO titer to 68.8 mg/L. The productivity of this optimized strain was then tested in a fed-batch stirred tank bioreactor, where final product concentrations of up to 86.2 mg/L with a yield of 0.0318 g-(2,3-BDO) /g-CH 4 were obtained under O 2 -limited conditions. This study first demonstrates the strategy of in silico simulation-guided metabolic engineering and represents a proof-of-concept for the production of value-added compounds using systematic approaches from engineered methanotrophs. Copyright © 2018 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Kinetics of Methane Production from Swine Manure and Buffalo Manure.

PubMed

Sun, Chen; Cao, Weixing; Liu, Ronghou

2015-10-01

The degradation kinetics of swine and buffalo manure for methane production was investigated. Six kinetic models were employed to describe the corresponding experimental data. These models were evaluated by two statistical measurements, which were root mean square prediction error (RMSPE) and Akaike's information criterion (AIC). The results showed that the logistic and Fitzhugh models could predict the experimental data very well for the digestion of swine and buffalo manure, respectively. The predicted methane yield potential for swine and buffalo manure was 487.9 and 340.4 mL CH4/g volatile solid (VS), respectively, which was close to experimental values, when the digestion temperature was 36 ± 1 °C in the biochemical methane potential assays. Besides, the rate constant revealed that swine manure had a much faster methane production rate than buffalo manure.

Microbial Methane Production Associated with Carbon Steel Corrosion in a Nigerian Oil Field

PubMed Central

Mand, Jaspreet; Park, Hyung S.; Okoro, Chuma; Lomans, Bart P.; Smith, Seun; Chiejina, Leo; Voordouw, Gerrit

2016-01-01

Microbially influenced corrosion (MIC) in oil field pipeline systems can be attributed to many different types of hydrogenotrophic microorganisms including sulfate reducers, methanogens and acetogens. Samples from a low temperature oil reservoir in Nigeria were analyzed using DNA pyrotag sequencing. The microbial community compositions of these samples revealed an abundance of anaerobic methanogenic archaea. Activity of methanogens was demonstrated by incubating samples anaerobically in a basal salts medium, in the presence of carbon steel and carbon dioxide. Methane formation was measured in all enrichments and correlated with metal weight loss. Methanogens were prominently represented in pipeline solids samples, scraped from the inside of a pipeline, comprising over 85% of all pyrosequencing reads. Methane production was only witnessed when carbon steel beads were added to these pipeline solids samples, indicating that no methane was formed as a result of degradation of the oil organics present in these samples. These results were compared to those obtained for samples taken from a low temperature oil field in Canada, which had been incubated with oil, either in the presence or in the absence of carbon steel. Again, methanogens present in these samples catalyzed methane production only when carbon steel was present. Moreover, acetate production was also found in these enrichments only in the presence of carbon steel. From these studies it appears that carbon steel, not oil organics, was the predominant electron donor for acetate production and methane formation in these low temperature oil fields, indicating that the methanogens and acetogens found may contribute significantly to MIC. PMID:26793176

Rumen protozoa and methanogenesis: not a simple cause-effect relationship.

PubMed

Morgavi, Diego P; Martin, Cécile; Jouany, Jean-Pierre; Ranilla, Maria José

2012-02-01

Understanding the interactions between hydrogen producers and consumers in the rumen ecosystem is important for ruminant production and methane mitigation. The present study explored the relationships between rumen protozoa, methanogens and fermentation characteristics. A total of six donor sheep harbouring (F, faunated) or not (D, defaunated) protozoa in their rumens (D animals were kept without protozoa for a period of a few months (D - ) or for more than 2 years (D+)) were used in in vitro and in vivo experiments. In vitro the absence of protozoa decreased NH3 and butyrate production and had no effect on methane. In contrast, the liquid-associated bacterial and methanogens fraction of D+ inocula produced more methane than D -  and F inoculum (P < 0·05). In vivo fermentation parameters of donor animals showed the same trend on NH3 and butyrate and showed that D+ animals were high methane emitters, while D -  were the lowest ( - 35 %). The concentration of dissolved dihydrogen measured after feeding followed the opposite trend. Methane emissions did not correlate with the relative abundance of methanogens in the rumen measured by quantitative PCR, but there was a trend for higher methanogens concentration in the solid-associated population of D+ animals compared with D -  animals. In contrast, PCR-denaturing gradient gel electrophoresis profiles of methanogens' methyl coenzyme-M reductase A gene showed a clear clustering in liquid-associated fractions for all three groups of donors but fewer differences in solid-associated fractions. These results show that the absence of protozoa may affect differently the methanogen community and methane emissions in wethers.

Combustion of Methane Hydrate

NASA Astrophysics Data System (ADS)

Roshandell, Melika

A significant methane storehouse is in the form of methane hydrates on the sea floor and in the arctic permafrost. Methane hydrates are ice-like structures composed of water cages housing a guest methane molecule. This caged methane represents a resource of energy and a potential source of strong greenhouse gas. Most research related to methane hydrates has been focused on their formation and dissociation because they can form solid plugs that complicate transport of oil and gas in pipelines. This dissertation explores the direct burning of these methane hydrates where heat from the combustion process dissociates the hydrate into water and methane, and the released methane fuels the methane/air diffusion flame heat source. In contrast to the pipeline applications, very little research has been done on the combustion and burning characteristics of methane hydrates. This is the first dissertation on this subject. In this study, energy release and combustion characteristics of methane hydrates were investigated both theoretically and experimentally. The experimental study involved collaboration with another research group, particularly in the creation of methane hydrate samples. The experiments were difficult because hydrates form at high pressure within a narrow temperature range. The process can be slow and the resulting hydrate can have somewhat variable properties (e.g., extent of clathration, shape, compactness). The experimental study examined broad characteristics of hydrate combustion, including flame appearance, burning time, conditions leading to flame extinguishment, the amount of hydrate water melted versus evaporated, and flame temperature. These properties were observed for samples of different physical size. Hydrate formation is a very slow process with pure water and methane. The addition of small amounts of surfactant increased substantially the hydrate formation rate. The effects of surfactant on burning characteristics were also studied. One finding from the experimental component of the research was that hydrates can burn completely, and that they burn most rapidly just after ignition and then burn steadily when some of the water in the dissociated zone is allowed to drain away. Excessive surfactant in the water creates a foam layer around the hydrate that acts as an insulator. The layer prevents sufficient heat flux from reaching the hydrate surface below the foam to release additional methane and the hydrate flame extinguishes. No self-healing or ice-freezing processes were observed in any of the combustion experiments. There is some variability, but a typical hydrate flame is receiving between one and two moles of water vapor from the liquid dissociated zone of the hydrate for each mole of methane it receives from the dissociating solid region. This limits the flame temperature to approximately 1800 K. In the theoretical portion of the study, a physical model using an energy balance from methane combustion was developed to understand the energy transfer between the three phases of gas, liquid and solid during the hydrate burn. Also this study provides an understanding of the different factors impacting the hydrate's continuous burn, such as the amount of water vapor in the flame. The theoretical study revealed how the water layer thickness on the hydrate surface, and its effect on the temperature gradient through the dissociated zone, plays a significant role in the hydrate dissociation rate and methane release rate. Motivated by the above mentioned observation from the theoretical analysis, a 1-D two-phase numerical simulation based on a moving front model for hydrate dissociation from a thermal source was developed. This model was focused on the dynamic growth of the dissociated zone and its effect on the dissociation rate. The model indicated that the rate of hydrate dissociation with a thermal source is a function of the dissociated zone thickness. It shows that in order for a continuous dissociation and methane release, some of the water from the dissociated zone needs to be drained. The results are consistent with the experimental observations. The understanding derived from the experiments and the numerical model permitted a brief exploration into the potential effects of pressure on the combustion of methane hydrates. The prediction is that combustion should improve under high pressure conditions because the evaporation of water is suppressed allowing more energy into the dissociation. Future experiments are needed to validate these initial findings.

Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate.

PubMed

Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

2016-01-21

Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d(-1)) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery.

Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate

PubMed Central

Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

2016-01-01

Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d−1) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery. PMID:26791952

Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate

NASA Astrophysics Data System (ADS)

Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

2016-01-01

Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d-1) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery.

A correction in the CDM methodological tool for estimating methane emissions from solid waste disposal sites.

PubMed

Santos, M M O; van Elk, A G P; Romanel, C

2015-12-01

Solid waste disposal sites (SWDS) - especially landfills - are a significant source of methane, a greenhouse gas. Although having the potential to be captured and used as a fuel, most of the methane formed in SWDS is emitted to the atmosphere, mainly in developing countries. Methane emissions have to be estimated in national inventories. To help this task the Intergovernmental Panel on Climate Change (IPCC) has published three sets of guidelines. In addition, the Kyoto Protocol established the Clean Development Mechanism (CDM) to assist the developed countries to offset their own greenhouse gas emissions by assisting other countries to achieve sustainable development while reducing emissions. Based on methodologies provided by the IPCC regarding SWDS, the CDM Executive Board has issued a tool to be used by project developers for estimating baseline methane emissions in their project activities - on burning biogas from landfills or on preventing biomass to be landfilled and so avoiding methane emissions. Some inconsistencies in the first two IPCC guidelines have already been pointed out in an Annex of IPCC latest edition, although with hidden details. The CDM tool uses a model for methane estimation that takes on board parameters, factors and assumptions provided in the latest IPCC guidelines, while using in its core equation the one of the second IPCC edition with its shortcoming as well as allowing a misunderstanding of the time variable. Consequences of wrong ex-ante estimation of baseline emissions regarding CDM project activities can be of economical or environmental type. Example of the first type is the overestimation of 18% in an actual project on biogas from landfill in Brazil that harms its developers; of the second type, the overestimation of 35% in a project preventing municipal solid waste from being landfilled in China, which harms the environment, not for the project per se but for the undue generated carbon credits. In a simulated landfill - the same amount of waste for 20 years -, the error would be an overestimation of 25% if the CDM project activity starts from the very first year or an underestimation of 15% if it starts just after the landfill closure. Therefore, a correction in the tool to calculate emissions from landfills as adopted by the CDM Executive Board is needed. Moreover, in countries not using the latest IPCC guidelines, which provides clear formulas to prevent misunderstandings, inventory compilers can also benefit from this paper by having more accurate results in national GHG inventories related to solid waste disposal, especially when increasing amounts of waste are landfilled, which is the case of the developing countries. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of organic loading rate on methane production in a CSTR from physicochemical sludge generated in a poultry slaughterhouse.

PubMed

López-Escobar, Luis A; Martínez-Hernández, Sergio; Corte-Cano, Grisel; Méndez-Contreras, Juan M

2014-01-01

The influence of the increase of the organic loading rate (OLR) on methane production in a continuous stirred-tank reactor (CSTR) from physicochemical sludge generated in a poultry slaughterhouse was evaluated. Total solid (TS) to obtain OLR of 1, 5, 10 and 15 g VS L(-1) day(-1), with hydraulic retention times of 29, 6, 6 and 4, respectively, were conditioned. The results showed a decrease in pH levels and an increase in the theoretical volatile fatty acids (VFA). While the yield of methane production decreased from 0.48 to 0.10 LCH4/g VSremoved, respectively, the OLR-10 managed on average 38% removal of volatile solids (VS) and a yield biogas production of 0.81 Lbiogas g(-1) VSremoved and 1.35 L day(-1). This suggests that the OLR increases in an anaerobic system from physicochemical sludge only inhibits the methanogenic metabolism, because there is still substrate consumption and biogas production.

Anaerobic biodegradability of Category 2 animal by-products: methane potential and inoculum source.

PubMed

Pozdniakova, Tatiana A; Costa, José C; Santos, Ricardo J; Alves, M M; Boaventura, Rui A R

2012-11-01

Category 2 animal by-products that need to be sterilized with steam pressure according Regulation (EC) 1774/2002 are studied. In this work, 2 sets of experiments were performed in mesophilic conditions: (i) biomethane potential determination testing 0.5%, 2.0% and 5.0% total solids (TS), using sludge from the anaerobic digester of a wastewater treatment plant as inoculum; (ii) biodegradability tests at a constant TS concentration of 2.0% and different inoculum sources (digested sludge from a wastewater treatment plant; granular sludge from an upflow anaerobic sludge blanket reactor; leachate from a municipal solid waste landfill; and sludge from the slaughterhouse wastewater treatment anaerobic lagoon) to select the more adapted inoculum to the substrate in study. The higher specific methane production was of 317 mL CH(4)g(-1) VS(substrate) for 2.0% TS. The digested sludge from the wastewater treatment plant led to the lowest lag-phase period and higher methane potential rate. Copyright © 2012 Elsevier Ltd. All rights reserved.

Influence of the ultrasound pretreatment on anaerobic digestion of cattle manure, food waste and crude glycerine.

PubMed

Ormaechea, Pedro; Castrillón, Leonor; Marañón, Elena; Fernández-Nava, Yolanda; Negral, Luis; Megido, Laura

2017-03-01

To increase the production of methane, when cattle manure (CM) is digested, pretreatments can be applied and/or the manure can be co-digested with other wastes. In this research work, a mixture of CM, food waste (FW) and raw glycerine (Gly) in a proportion in weight of 87% CM, 10% FW and 3% Gly was digested, (a) without pretreatment and (b) with pretreatment by ultrasound, applying a sonication energy of 1040 kJ/kg total solids. Specific methane production was 290 L CH 4 /kg volatile solids (VS) without pretreatment and 520 L CH 4 /kg VS with pretreatment. With respect to the volumetric methane production, 1.07 L CH 4 /L reactor .day was produced in the first case, and in the second case, 1.98 L CH 4 /L reactor .day. We can conclude that the application of ultrasound pretreatment significantly improved the production of biogas.

Economic and environmental sustainability of an AnMBR treating urban wastewater and organic fraction of municipal solid waste.

PubMed

Pretel, R; Moñino, P; Robles, A; Ruano, M V; Seco, A; Ferrer, J

2016-09-01

The objective of this study was to evaluate the economic and environmental sustainability of a submerged anaerobic membrane bioreactor (AnMBR) treating urban wastewater (UWW) and organic fraction of municipal solid waste (OFMSW) at ambient temperature in mild/hot climates. To this aim, power requirements, energy recovery from methane (biogas methane and methane dissolved in the effluent), consumption of reagents for membrane cleaning, and sludge handling (polyelectrolyte and energy consumption) and disposal (farmland, landfilling and incineration) were evaluated within different operating scenarios. Results showed that, for the operating conditions considered in this study, AnMBR technology is likely to be a net energy producer, resulting in considerable cost savings (up to €0.023 per m(3) of treated water) when treating low-sulphate influent. Life cycle analysis (LCA) results revealed that operating at high sludge retention times (70 days) and treating UWW jointly with OFMSW enhances the overall environmental performance of AnMBR technology. Copyright © 2016 Elsevier Ltd. All rights reserved.

Methane Emission by Camelids

PubMed Central

Dittmann, Marie T.; Runge, Ullrich; Lang, Richard A.; Moser, Dario; Galeffi, Cordula; Kreuzer, Michael; Clauss, Marcus

2014-01-01

Methane emissions from ruminant livestock have been intensively studied in order to reduce contribution to the greenhouse effect. Ruminants were found to produce more enteric methane than other mammalian herbivores. As camelids share some features of their digestive anatomy and physiology with ruminants, it has been proposed that they produce similar amounts of methane per unit of body mass. This is of special relevance for countrywide greenhouse gas budgets of countries that harbor large populations of camelids like Australia. However, hardly any quantitative methane emission measurements have been performed in camelids. In order to fill this gap, we carried out respiration chamber measurements with three camelid species (Vicugna pacos, Lama glama, Camelus bactrianus; n = 16 in total), all kept on a diet consisting of food produced from alfalfa only. The camelids produced less methane expressed on the basis of body mass (0.32±0.11 L kg−1 d−1) when compared to literature data on domestic ruminants fed on roughage diets (0.58±0.16 L kg−1 d−1). However, there was no significant difference between the two suborders when methane emission was expressed on the basis of digestible neutral detergent fiber intake (92.7±33.9 L kg−1 in camelids vs. 86.2±12.1 L kg−1 in ruminants). This implies that the pathways of methanogenesis forming part of the microbial digestion of fiber in the foregut are similar between the groups, and that the lower methane emission of camelids can be explained by their generally lower relative food intake. Our results suggest that the methane emission of Australia's feral camels corresponds only to 1 to 2% of the methane amount produced by the countries' domestic ruminants and that calculations of greenhouse gas budgets of countries with large camelid populations based on equations developed for ruminants are generally overestimating the actual levels. PMID:24718604

Sulfide and methane production in sewer sediments.

PubMed

Liu, Yiwen; Ni, Bing-Jie; Ganigué, Ramon; Werner, Ursula; Sharma, Keshab R; Yuan, Zhiguo

2015-03-01

Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m(2)·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH4/m(2)·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics. Copyright © 2014 Elsevier Ltd. All rights reserved.

Solid state anaerobic co-digestion of tomato residues with dairy manure and corn stover for biogas production.

PubMed

Li, Yangyang; Li, Yu; Zhang, Difang; Li, Guoxue; Lu, Jiaxin; Li, Shuyan

2016-10-01

Solid-state anaerobic co-digestion of tomato residues with dairy manure and corn stover was conducted at 20% total solids under 35°C for 45days. Results showed digestion of mixed tomato residues with dairy manure and corn stover improved methane yields. The highest VS reduction (46.2%) and methane yield (415.4L/kg VSfeed) were achieved with the ternary mixtures of 33% corn stover, 54% dairy manure, and 13% tomato residues, lead to a 0.5-10.2-fold higher than that of individual feedstocks. Inhibition of volatile fatty acids (VFAs) to biogas production occurred when more than 40% tomato residues were added. The results indicated that ternary mixtures diluted the inhibitors that would otherwise cause inhibition in the digestion of tomato residues as a mono-feedstock. Copyright © 2016. Published by Elsevier Ltd.

Stimulation of the anaerobic digestion of the dry organic fraction of municipal solid waste (OFMSW) with carbon-based conductive materials.

PubMed

Dang, Yan; Sun, Dezhi; Woodard, Trevor L; Wang, Li-Ying; Nevin, Kelly P; Holmes, Dawn E

2017-08-01

Growth of bacterial and archaeal species capable of interspecies electron exchange was stimulated by addition of conductive materials (carbon cloth or granular activated carbon (GAC)) to anaerobic digesters treating dog food (a substitute for the dry-organic fraction of municipal solid waste (OFMSW)). Methane production (772-1428mmol vs <80mmol), volatile solids removal (78%-81% vs 54%-64%) and COD removal efficiencies (∼80% vs 20%-30%) were all significantly higher in reactors amended with GAC or carbon cloth than controls. OFMSW degradation was also significantly accelerated and VFA concentrations were substantially lower in reactors amended with conductive materials. These results suggest that both conductive materials (carbon cloth and GAC) can promote conversion of OFMSW to methane even in the presence of extremely high VFA concentrations (∼500mM). Copyright © 2017 Elsevier Ltd. All rights reserved.

Dependence of Surface Contrast on Emission Angle in Cassini ISS 938-nm Images of Titan

NASA Technical Reports Server (NTRS)

Fussner, S.; McEwen, A.; Perry, J.; Turtle, E.; Dawson, D.; Porco, C.; West, R.

2005-01-01

Titan, the largest of Saturn s moons, is one of the most difficult solid surfaces in the Solar System to study. It is shrouded in a thick atmosphere with fine haze particles extending up to 500 km. [1] The atmosphere itself is rich in methane, which allows clear viewing of the surface only through narrow "windows" in the methane spectrum. Even in these methane windows, the haze absorbs and scatters light, blurring surface features and reducing the contrast of images. The haze optical depth is high at visible wavelengths, and decreases at longer (infrared) wavelengths. [2

Thermal conductivity measurements in porous mixtures of methane hydrate and quartz sand

USGS Publications Warehouse

Waite, W.F.; deMartin, B.J.; Kirby, S.H.; Pinkston, J.; Ruppel, C.D.

2002-01-01

Using von Herzen and Maxwell's needle probe method, we measured thermal conductivity in four porous mixtures of quartz sand and methane gas hydrate, with hydrate composing 0, 33, 67 and 100% of the solid volume. Thermal conductivities were measured at a constant methane pore pressure of 24.8 MPa between -20 and +15??C, and at a constant temperature of -10??C between 3.5 and 27.6 MPa methane pore pressure. Thermal conductivity decreased with increasing temperature and increased with increasing methane pore pressure. Both dependencies weakened with increasing hydrate content. Despite the high thermal conductivity of quartz relative to methane hydrate, the largest thermal conductivity was measured in the mixture containing 33% hydrate rather than in hydrate-free sand. This suggests gas hydrate enhanced grain-to-grain heat transfer, perhaps due to intergranular contact growth during hydrate synthesis. These results for gas-filled porous mixtures can help constrain thermal conductivity estimates in porous, gas hydrate-bearing systems.

Biodegradability and methane production from secondary paper and pulp sludge: effect of fly ash and modeling.

PubMed

Huiliñir, César; Montalvo, Silvio; Guerrero, Lorna

2015-01-01

The effect of fly ash on biodegradability and methane production from secondary paper and pulp sludge, including its modeling, was evaluated. Three tests with fly ash concentrations of 0, 10 and 20 mg/L were evaluated at 32 °C. Methane production was modeled using the modified Gompertz equation. The results show that the doses used produce a statistically significant increase of accumulated methane, giving values greater than 225 mL of CH4 per gram of volatile solids (VS) added, and 135% greater than that obtained in the control assay. Biodegradability of VS increased 143% with respect to the control assays, giving values around 43%. The modified Gompertz model can describe well methane generation from residual sludge of the paper industry water treatment, with parameter values between those reported in the literature. Thus, the addition of fly ash to the process causes a significant increase of accumulated methane and VS removal, improving the biodegradability of paper and pulp sludge.

Enhanced methane generation during theromophilic co-digestion of confectionary waste and grease-trap fats and oils with municipal wastewater sludge.

PubMed

Gough, Heidi L; Nelsen, Diane; Muller, Christopher; Ferguson, John

2013-02-01

Recent interest in carbon-neutral biofuels has revived interest in co-digestion for methane generation. At wastewater treatment facilities, organic wastes may be co-digested with sludge using established anaerobic digesters. However, changes to organic loadings may induce digester instability, particularly for thermophilic digesters. To examine this problem, thermophilic (55 degrees C) co-digestion was studied for two food-industry wastes in semi-continuous laboratory digesters; in addition, the wastes' biochemical methane potentials were tested. Wastes with high chemical oxygen demand (COD) content were selected as feedstocks allowing increased input of potential energy to reactors without substantially altering volumetric loadings. Methane generation increased while reactor pH and volatile solids remained stable. Lag periods observed prior to methane stimulation suggested that acclimation of the microbial community may be critical to performance during co-digestion. Chemical oxygen demand mass balances in the experimental and control reactors indicated that all of the food industry waste COD was converted to methane.

Effect of ensiling and silage additives on biogas production and microbial community dynamics during anaerobic digestion of switchgrass.

PubMed

Zhao, Xiaoling; Liu, Jinhuan; Liu, Jingjing; Yang, Fuyu; Zhu, Wanbin; Yuan, Xufeng; Hu, Yuegao; Cui, Zongjun; Wang, Xiaofen

2017-10-01

Silage processing has a crucial positive impact on the methane yield of anaerobic treated substrates. Changes in the characteristics of switchgrass after ensiling with different additives and their effects on methane production and microbial community changes during anaerobic digestion were investigated. After ensiling (CK), methane yield was increased by 33.59% relative to that of fresh switchgrass (FS). In comparison with the CK treatment, methane production was improved by 17.41%, 13.08% and 8.72% in response to ensiling with LBr+X, LBr and X, respectively. A modified Gompertz model predicted that the optimum treatment was LBr+X, with a potential cumulative methane yield of 178.31mL/g total solids (TS) and a maximum biogas production rate of 44.39mL/g TS·d. Firmicutes and Bacteroidetes were the predominant bacteria in FS and silage switchgrass; however, the switchgrass treated with LBr+X was rich in Synergistetes, which was crucial for methane production. Copyright © 2017. Published by Elsevier Ltd.

Semi-continuous anaerobic co-digestion of cow manure and steam-exploded Salix with recirculation of liquid digestate.

PubMed

Estevez, Maria M; Sapci, Zehra; Linjordet, Roar; Schnürer, Anna; Morken, John

2014-04-01

The effects of recirculating the liquid fraction of the digestate during mesophilic anaerobic co-digestion of steam-exploded Salix and cow manure were investigated in laboratory-scale continuously stirred tank reactors. An average organic loading rate of 2.6 g VS L(-1) d(-1) and a hydraulic retention time (HRT) of 30 days were employed. Co-digestion of Salix and manure gave better methane yields than digestion of manure alone. Also, a 16% increase in the methane yield was achieved when digestate was recirculated and used instead of water to dilute the feedstock (1:1 dilution ratio). The reactor in which the larger fraction of digestate was recirculated (1:3 dilution ratio) gave the highest methane yields. Ammonia and volatile fatty acids did not reach inhibitory levels, and some potentially inhibitory compounds released during steam explosion (i.e., furfural and 5-hydroxy methyl furfural) were only detected at trace levels throughout the entire study period. However, accumulation of solids, which was more pronounced in the recycling reactors, led to decreased methane yields in those systems after three HRTs. Refraining from the use of fresh water to dilute biomass with a high-solids content and obtaining a final digestate with increased dry matter content might offer important economic benefits in full-scale processes. To ensure long-term stability in such an approach, it would be necessary to optimize separation of the fraction of digestate to be recirculated and also perform proper monitoring to avoid accumulation of solids. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhancing methane production from waste activated sludge using a novel indigenous iron activated peroxidation pre-treatment process.

PubMed

Zhou, Xu; Wang, Qilin; Jiang, Guangming

2015-04-01

Methane production from anaerobic digestion of waste activated sludge (WAS) is limited by the slow hydrolysis rate and/or poor methane potential of WAS. This study presents a novel pre-treatment strategy based on indigenous iron (in WAS) activated peroxidation to enhance methane production from WAS. Pre-treatment of WAS for 30 min at 50mg H2O2/g total solids (dry weight) and pH 2.0 (iron concentration in WAS was 7 mg/g TS) substantially enhanced WAS solubilization. Biochemical methane potential tests demonstrated that methane production was improved by 10% at a digestion time of 16d after incorporating the indigenous iron activated peroxidation pre-treatment. Model-based analysis indicated that indigenous iron activated peroxidation pre-treatment improved the methane potential by 13%, whereas the hydrolysis rate was not significantly affected. The economic analysis showed that the proposed pre-treatment method can save the cost by $112,000 per year in a treatment plant with a population equivalent of 300,000. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of starchy or fibrous carbohydrate supplementation of orchardgrass on ruminal fermentation and methane output in continuous culture

USDA-ARS?s Scientific Manuscript database

A 4-unit dual-flow continuous culture fermentor system was used to assess the effect of supplementing an orchardgrass (Dactylis glomerata L.) herbage diet with 2 levels [5 and 10% of total dry matter (DM) fed] of starchy (barley grain; BAR) or fibrous (beet pulp; BP) carbohydrates on nutrient diges...

Performance, digestion, nitrogen balance, and emission of manure ammonia, enteric methane, and carbon dioxide in lactating cows fed diets with varying alfalfa silage-to-corn silage ratios

USDA-ARS?s Scientific Manuscript database

Two trials were conducted simultaneously to study the effect of alfalfa silage (AS) to corn silage (CS) ratio in the diet of lactating dairy cows on performance, digestibility, ruminal parameters, nitrogen (N) balance, manure production and composition, and gaseous emissions [carbon dioxide (CO2), ...

Effects of source and level of dietary energy supplementation on in vitro digestibility and methane production from tall fescue-based diets

USDA-ARS?s Scientific Manuscript database

There is a lack of information about the effect of different sources, levels, and the mixtures of energy supplements commonly fed to cattle grazing tall fescue. Therefore, the objective of this study was to evaluate different common energy sources for beef cattle grazing tall fescue using an in vitr...

Performance and kinetic evaluation of semi-continuously fed anaerobic digesters treating food waste: role of trace elements.

PubMed

Zhang, Wanqin; Wu, Shubiao; Guo, Jianbin; Zhou, Jie; Dong, Renjie

2015-02-01

This study investigated the effects of trace elements (TEs) on the anaerobic digestion (AD) of food waste (FW) in laboratory-scale semi-continuously fed anaerobic digesters. The duration of digesters operation was approximately 400 days. Organic loading rates (OLRs) ranged from 1.0 to 5.5 g VS L(-1) d(-1) at 37 °C. Results showed that methane production of the digester was severely inhibited at a volatile fatty acid (VFA) concentration of 30,000 mg L(-1) at OLR of 4.0 g VS L(-1) d(-1) in the absence of TEs. Contrary to the failed digesters, a stable performance was achieved in the TEs added digesters. High methane yield (approximately 465.4 mL CH4 g(-1)VSadded) was obtained, and no significant accumulation of VFA was observed in the TEs added digesters at OLR of 1.0-5.0 g VS L(-1) d(-1) and HRT of 40 days. These findings strongly indicated that the addition of TEs has an important impact on the operation stability of AD of FW. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of dried solids of nejayote on broiler growth.

PubMed

Velasco-Martinez, M; Angulo, O; Vazquez-Couturier, D L; Arroyo-Lara, A; Monroy-Rivera, J A

1997-11-01

The purpose of the present study was to test the suitability of the solids of nejayote (a waste product from the tortilla industry) in diets for broilers. The nejayote was obtained from two different tortilla-making factories and the solids were obtained by centrifuge then dried in a hot-air drier. Diets were formulated to be isocaloric and isonitrogenous according to the NRC dietary requirements (1994). Nejayote solids were supplemented at 2, 4, and 6% of the diet. Results show that the content of protein and calcium in the dried solids of nejayote were 5 and 13%, respectively. The performance of broilers fed diets supplemented with dried nejayote did not differ from that of those fed the control diet. Therefore, it is concluded that nejayote solids are suitable for broiler feed and do not affect growth performance. Utilization of nejayote solids at higher levels is a possibility provided that no adverse effects on body weight, feed utilization, and feed:gain ratios are observed.

Fungal pretreatment of albizia chips for enhanced biogas production by solid-state anaerobic digestion

USDA-ARS?s Scientific Manuscript database

Albizia biomass is a forestry waste, and holds a great potential in biogas production by solid-state anaerobic digestion (SS-AD). However, low methane yields from albizia chips were observed due to their recalcitrant structure. In this study, albizia chips were pretreated by Ceriporiopsis subvermisp...

Need for improvements in physical pretreatment of source-separated household food waste.

PubMed

Bernstad, A; Malmquist, L; Truedsson, C; la Cour Jansen, J

2013-03-01

The aim of the present study was to investigate the efficiency in physical pretreatment processes of source-separated solid organic household waste. The investigation of seventeen Swedish full-scale pretreatment facilities, currently receiving separately collected food waste from household for subsequent anaerobic digestion, shows that problems with the quality of produced biomass and high maintenance costs are common. Four full-scale physical pretreatment plants, three using screwpress technology and one using dispergation technology, were compared in relation to resource efficiency, losses of nitrogen and potential methane production from biodegradable matter as well as the ratio of unwanted materials in produced biomass intended for wet anaerobic digestion. Refuse generated in the processes represent 13-39% of TS in incoming wet waste. The methane yield from these fractions corresponds to 14-36Nm(3)/ton separately collected solid organic household waste. Also, 13-32% of N-tot in incoming food waste is found in refuse. Losses of both biodegradable material and nutrients were larger in the three facilities using screwpress technology compared to the facility using dispersion technology.(1) Thus, there are large potentials for increase of both the methane yield and nutrient recovery from separately collected solid organic household waste through increased efficiency in facilities for physical pretreatment. Improved pretreatment processes could thereby increase the overall environmental benefits from anaerobic digestion as a treatment alternative for solid organic household waste. Copyright © 2012 Elsevier Ltd. All rights reserved.

Supplementation of Flemingia macrophylla and cassava foliage as a rumen enhancer on fermentation efficiency and estimated methane production in dairy steers.

PubMed

Phesatcha, Burarat; Wanapat, Metha; Phesatcha, Kampanat; Ampapon, Thiwakorn; Kang, Sungchhang

2016-10-01

Four rumen-fistulated dairy steers, 3 years old with 180 ± 15 kg body weight (BW), were randomly assigned according to a 4 × 4 Latin square design to investigate on the effect of Flemingia macrophylla hay meal (FMH) and cassava hay meal (CH) supplementation on rumen fermentation efficiency and estimated methane production. The treatments were as follows: T1 = non-supplement, T2 = CH supplementation at 150 g/head/day, T3 = FMH supplementation at 150 g/head/day, and T4 = CH + FMH supplementation at 75 and 75 g/head/day. All steers were fed rice straw ad libitum and concentrate was offered at 0.5 % of BW. Results revealed that supplementation of CH and/or FMH did not affect on feed intake (P > 0.05) while digestibility of crude protein and neutral detergent fiber were increased especially in steers receiving FMH and CH+FMH (P < 0.05). Ruminal pH, temperature, and blood urea nitrogen were similar among treatments while ammonia nitrogen was increased in all supplemented groups (P < 0.05). Furthermore, propionic acid (C3) was increased while acetic acid (C2), C2:C3 ratio, and estimated methane production were decreased by dietary treatments. Protozoa and fungi population were not affected by dietary supplement while viable bacteria count increased in steers receiving FMH. Supplementation of FMH and/or FMH+CH increased microbial crude protein and efficiency of microbial nitrogen supply. This study concluded FMH (150 g/head/day) and/or CH+FMH (75 and 75 g/head/day) supplementation could be used as a rumen enhancer for increasing nutrient digestibility, rumen fermentation efficiency, and microbial protein synthesis while decreasing estimated methane production without adverse effect on voluntary feed intake of dairy steers fed rice straw.

Development of methane conversion factor models for Zebu beef cattle fed low-quality crop residues and by-products in tropical regions.

PubMed

Kaewpila, Chatchai; Sommart, Kritapon

2016-10-01

The enteric methane conversion factor ( Y m ) is an important country-specific value for the provision of precise enteric methane emissions inventory reports. The objectives of this meta-analysis were to develop and evaluate the empirical Y m models for the national level and the farm level for tropical developing countries according to the IPCC's categorization. We used datasets derived from 18 in vivo feeding experiments from 1999 to 2015 of Zebu beef cattle breeds fed low-quality crop residues and by-products. We found that the observed Y m value was 8.2% gross energy (GE) intake (~120 g methane emission head -1  day -1 ) and ranged from 4.8% to 13.7% GE intake. The IPCC default model (tier 2, Y m  = 6.5% ± 1.0% GE intake) underestimated the Y m values by up to 26.1% compared with its refinement of 8.4% ± 0.4% GE intake for the national-level estimate. Both the IPCC default model and the refined model performed worse in predicting Y m trends at the farm level (root mean square prediction error [MSPE] = 15.1%-23.1%, concordance correlation coefficient [CCC] = 0.16-0.18, R 2  = .32). Seven of the extant Y m models based on a linear regression approach also showed inaccurately estimated Y m values (root MSPE = 16.2%-36.0%, CCC = 0.02-0.27, R 2  < .37). However, one of the developed models, which related to the complexity of the energy use efficiencies of the diet consumed to Y m , showed adequate accuracy at the farm level (root MSPE = 9.1%, CCC = 0.75, R 2  = .67). Our results thus suggest a new Y m model and future challenges for estimating Zebu beef cattle production in tropical developing countries.

Nonequilibrium adiabatic molecular dynamics simulations of methane clathrate hydrate decomposition

NASA Astrophysics Data System (ADS)

Alavi, Saman; Ripmeester, J. A.

2010-04-01

Nonequilibrium, constant energy, constant volume (NVE) molecular dynamics simulations are used to study the decomposition of methane clathrate hydrate in contact with water. Under adiabatic conditions, the rate of methane clathrate decomposition is affected by heat and mass transfer arising from the breakup of the clathrate hydrate framework and release of the methane gas at the solid-liquid interface and diffusion of methane through water. We observe that temperature gradients are established between the clathrate and solution phases as a result of the endothermic clathrate decomposition process and this factor must be considered when modeling the decomposition process. Additionally we observe that clathrate decomposition does not occur gradually with breakup of individual cages, but rather in a concerted fashion with rows of structure I cages parallel to the interface decomposing simultaneously. Due to the concerted breakup of layers of the hydrate, large amounts of methane gas are released near the surface which can form bubbles that will greatly affect the rate of mass transfer near the surface of the clathrate phase. The effects of these phenomena on the rate of methane hydrate decomposition are determined and implications on hydrate dissociation in natural methane hydrate reservoirs are discussed.

Nonequilibrium adiabatic molecular dynamics simulations of methane clathrate hydrate decomposition.

PubMed

Alavi, Saman; Ripmeester, J A

2010-04-14

Nonequilibrium, constant energy, constant volume (NVE) molecular dynamics simulations are used to study the decomposition of methane clathrate hydrate in contact with water. Under adiabatic conditions, the rate of methane clathrate decomposition is affected by heat and mass transfer arising from the breakup of the clathrate hydrate framework and release of the methane gas at the solid-liquid interface and diffusion of methane through water. We observe that temperature gradients are established between the clathrate and solution phases as a result of the endothermic clathrate decomposition process and this factor must be considered when modeling the decomposition process. Additionally we observe that clathrate decomposition does not occur gradually with breakup of individual cages, but rather in a concerted fashion with rows of structure I cages parallel to the interface decomposing simultaneously. Due to the concerted breakup of layers of the hydrate, large amounts of methane gas are released near the surface which can form bubbles that will greatly affect the rate of mass transfer near the surface of the clathrate phase. The effects of these phenomena on the rate of methane hydrate decomposition are determined and implications on hydrate dissociation in natural methane hydrate reservoirs are discussed.

Ductile flow of methane hydrate

USGS Publications Warehouse

Durham, W.B.; Stern, L.A.; Kirby, S.H.

2003-01-01

Compressional creep tests (i.e., constant applied stress) conducted on pure, polycrystalline methane hydrate over the temperature range 260-287 K and confining pressures of 50-100 MPa show this material to be extraordinarily strong compared to other icy compounds. The contrast with hexagonal water ice, sometimes used as a proxy for gas hydrate properties, is impressive: over the thermal range where both are solid, methane hydrate is as much as 40 times stronger than ice at a given strain rate. The specific mechanical response of naturally occurring methane hydrate in sediments to environmental changes is expected to be dependent on the distribution of the hydrate phase within the formation - whether arranged structurally between and (or) cementing sediments grains versus passively in pore space within a sediment framework. If hydrate is in the former mode, the very high strength of methane hydrate implies a significantly greater strain-energy release upon decomposition and subsequent failure of hydrate-cemented formations than previously expected.

Continuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dong-Hoon; Oh, Sae-Eun, E-mail: saeun@hanbat.ac.kr

2011-09-15

Highlights: > High-solids (dry) anaerobic digestion is attracting a lot of attention these days. > One reactor was fed with food waste (FW) and paper waste. > Maximum biogas production rate of 5.0 m{sup 3}/m{sup 3}/d was achieved at HRT 40 d and 40% TS. > The other reactor was fed with FW and livestock waste (LW). > Until a 40% LW content increase, the reactor exhibited a stable performance. - Abstract: With increasing concerns over the limited capacity of landfills, conservation of resources, and reduction of CO{sub 2} emissions, high-solids (dry) anaerobic digestion of organic solid waste (OSW) ismore » attracting a great deal of attention these days. In the present work, two dry anaerobic co-digestion systems fed with different mixtures of OSW were continuously operated under mesophilic conditions. Dewatered sludge cake was used as a main seeding source. In reactor (I), which was fed with food waste (FW) and paper waste (PW), hydraulic retention time (HRT) and solid content were controlled to find the maximum treatability. At a fixed solid content of 30% total solids (TS), stable performance was maintained up to an HRT decrease to 40 d. However, the stable performance was not sustained at 30 d HRT, and hence, HRT was increased to 40 d again. In further operation, instead of decreasing HRT, solid content was increased to 40% TS, which was found to be a better option to increase the treatability. The biogas production rate (BPR), CH{sub 4} production yield (MPY) and VS reduction achieved in this condition were 5.0 m{sup 3}/m{sup 3}/d, 0.25 m{sup 3} CH{sub 4}/g COD{sub added}, and 80%, respectively. Reactor (II) was fed with FW and livestock waste (LW), and LW content was increased during the operation. Until a 40% LW content increase, reactor (II) exhibited a stable performance. A BPR of 1.7 m{sup 3}/m{sup 3}/d, MPY of 0.26 m{sup 3} CH{sub 4}/g COD{sub added}, and VS reduction of 72% was achieved at 40% LW content. However, when the LW content was increased to 60%, there was a significant performance drop, which was attributed to free ammonia inhibition. The performances in these two reactors were comparable to the ones achieved in the conventional wet digestion and thermophilic dry digestion processes.« less

Feasibility of thermophilic anaerobic processes for treating waste activated sludge under low HRT and intermittent mixing.

PubMed

Leite, Wanderli; Magnus, Bruna Scandolara; Guimarães, Lorena Bittencourt; Gottardo, Marco; Belli Filho, Paulo

2017-10-01

Thermophilic anaerobic digestion (AD) arises as an optimized solution for the waste activated sludge (WAS) management. However, there are few feasibility studies using low solids content typically found in the WAS, and that consider uncommon operational conditions such as intermittent mixing and low hydraulic retention time (HRT). In this investigation, a single-stage pilot reactor was used to treat WAS at low HRT (13, 9, 6 and 5 days) and intermittent mixing (withholding mixing 2 h prior feeding). Thermophilic anaerobic digestion (55 °C) was initiated from a mesophilic digester (35 °C) by the one-step startup strategy. Although instabilities on partial alkalinity (1245-3000 mgCaCO 3 /L), volatile fatty acids (1774-6421 mg/L acetic acid) and biogas production (0.21-0.09 m 3 /m 3 reactor .d) were observed, methanogenesis started to recover in 18 days. The thermophilic treatment of WAS at 13 and 9 days HRT efficiently converted VS into biogas (22 and 21%, respectively) and achieved high biogas yield (0.24 and 0.22 m 3 /kgVS fed , respectively). Intermittent mixing improved the retention of methanogens inside the reactor and reduced the washout effect even at low HRT (<9 days). The negative thermal balance found was influenced by the low solids content in the WAS (2.1% TS) and by the heat losses from the digester walls. The energy balance and economic analyses demonstrated the feasibility of thermophilic AD of WAS in a hypothetical full-scale system, when the heat energy could be recovered from methane in a scenario of higher solids concentration in the substrate (>5% TS). Copyright © 2017 Elsevier Ltd. All rights reserved.

Microbial communities of biomethanization digesters fed with raw and heat pre-treated microalgae biomasses.

PubMed

Sanz, Jose Luis; Rojas, Patricia; Morato, Ana; Mendez, Lara; Ballesteros, Mercedes; González-Fernández, Cristina

2017-02-01

Microalgae biomasses are considered promising feedstocks for biofuel and methane productions. Two Continuously Stirred Tank Reactors (CSTR), fed with fresh (CSTR-C) and heat pre-treated (CSTR-T) Chlorella biomass were run in parallel in order to determine methane productions. The methane yield was 1.5 times higher in CSTR-T with regard to CSTR-C. Aiming to understand the microorganism roles within of the reactors, the sludge used as an inoculum (I), plus raw (CSTR-C) and heat pre-treated (CSTR-T) samples were analyzed by high-throughput pyrosequencing. The bacterial communities were dominated by Proteobacteria, Bacteroidetes, Chloroflexi and Firmicutes. Spirochaetae and Actinobacteria were only detected in sample I. Proteobacteria, mainly Alfaproteobacteria, were by far the dominant phylum within of the CSTR-C bioreactor. Many of the sequences retrieved were related to bacteria present in activated sludge treatment plants and they were absent after thermal pre-treatment. Most of the sequences affiliated to the Bacteroidetes were related to uncultured groups. Anaerolineaceae was the sole family found of the Chloroflexi phylum. All of the genera identified of the Firmicutes phylum carried out macromolecule hydrolysis and by-product fermentation. The proteolytic bacteria were prevalent over the saccharolytic microbes. The percentage of the proteolytic genera increased from the inoculum to the CSTR-T sample in a parallel fashion with an available protein increase owing to the high protein content of Chlorella. To relate the taxa identified by high-throughput sequencing to their functional roles remains a future challenge. Copyright © 2016 Elsevier Ltd. All rights reserved.

Methane emissions from MBT landfills

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heyer, K.-U., E-mail: heyer@ifas-hamburg.de; Hupe, K.; Stegmann, R.

2013-09-15

Highlights: • Compilation of methane generation potential of mechanical biological treated (MBT) municipal solid waste. • Impacts and kinetics of landfill gas production of MBT landfills, approach with differentiated half-lives. • Methane oxidation in the waste itself and in soil covers. • Estimation of methane emissions from MBT landfills in Germany. - Abstract: Within the scope of an investigation for the German Federal Environment Agency (“Umweltbundesamt”), the basics for the estimation of the methane emissions from the landfilling of mechanically and biologically treated waste (MBT) were developed. For this purpose, topical research including monitoring results regarding the gas balance atmore » MBT landfills was evaluated. For waste treated to the required German standards, a methane formation potential of approximately 18–24 m{sup 3} CH{sub 4}/t of total dry solids may be expected. Monitoring results from MBT landfills show that a three-phase model with differentiated half-lives describes the degradation kinetics in the best way. This is due to the fact that during the first years of disposal, the anaerobic degradation processes still proceed relatively intensively. In addition in the long term (decades), a residual gas production at a low level is still to be expected. Most of the soils used in recultivation layer systems at German landfills show a relatively high methane oxidation capacity up to 5 l CH{sub 4}/(m{sup 2} h). However, measurements at MBT disposal sites indicate that the majority of the landfill gas (in particular at non-covered areas), leaves the landfill body via preferred gas emission zones (hot spots) without significant methane oxidation. Therefore, rather low methane oxidation factors are recommended for open and temporarily covered MBT landfills. Higher methane oxidation rates can be achieved when the soil/recultivation layer is adequately designed and operated. Based on the elaborated default values, the First Order Decay (FOD) model of the IPCC Guidelines for National Greenhouse Gas Inventories, 2006, was used to estimate the methane emissions from MBT landfills. Due to the calculation made by the authors emissions in the range of 60,000–135,000 t CO{sub 2-eq.}/a for all German MBT landfills can be expected. This wide range shows the uncertainties when the here used procedure and the limited available data are applied. It is therefore necessary to generate more data in the future in order to calculate more precise methane emission rates from MBT landfills. This is important for the overall calculation of the climate gas production in Germany which is required once a year by the German Government.« less

Trace Elements Induce Predominance among Methanogenic Activity in Anaerobic Digestion

PubMed Central

Wintsche, Babett; Glaser, Karin; Sträuber, Heike; Centler, Florian; Liebetrau, Jan; Harms, Hauke; Kleinsteuber, Sabine

2016-01-01

Trace elements (TE) play an essential role in all organisms due to their functions in enzyme complexes. In anaerobic digesters, control, and supplementation of TEs lead to stable and more efficient methane production processes while TE deficits cause process imbalances. However, the underlying metabolic mechanisms and the adaptation of the affected microbial communities to such deficits are not yet fully understood. Here, we investigated the microbial community dynamics and resulting process changes induced by TE deprivation. Two identical lab-scale continuous stirred tank reactors fed with distiller’s grains and supplemented with TEs (cobalt, molybdenum, nickel, tungsten) and a commercial iron additive were operated in parallel. After 72 weeks of identical operation, the feeding regime of one reactor was changed by omitting TE supplements and reducing the amount of iron additive. Both reactors were operated for further 21 weeks. Various process parameters (biogas production and composition, total solids and volatile solids, TE concentration, volatile fatty acids, total ammonium nitrogen, total organic acids/alkalinity ratio, and pH) and the composition and activity of the microbial communities were monitored over the total experimental time. While the methane yield remained stable, the concentrations of hydrogen sulfide, total ammonia nitrogen, and acetate increased in the TE-depleted reactor compared to the well-supplied control reactor. Methanosarcina and Methanoculleus dominated the methanogenic communities in both reactors. However, the activity ratio of these two genera was shown to depend on TE supplementation explainable by different TE requirements of their energy conservation systems. Methanosarcina dominated the well-supplied anaerobic digester, pointing to acetoclastic methanogenesis as the dominant methanogenic pathway. Under TE deprivation, Methanoculleus and thus hydrogenotrophic methanogenesis was favored although Methanosarcina was not overgrown by Methanoculleus. Multivariate statistics revealed that the decline of nickel, cobalt, molybdenum, tungsten, and manganese most strongly influenced the balance of mcrA transcripts from both genera. Hydrogenotrophic methanogens seem to be favored under nickel- and cobalt-deficient conditions as their metabolism requires less nickel-dependent enzymes and corrinoid cofactors than the acetoclastic and methylotrophic pathways. Thus, TE supply is critical to sustain the activity of the versatile high-performance methanogen Methanosarcina. PMID:28018337

An Effective Method to Detect Volatile Intermediates Generated in the Bioconversion of Coal to Methane by Gas Chromatography-Mass Spectrometry after In-Situ Extraction Using Headspace Solid-Phase Micro-Extraction under Strict Anaerobic Conditions.

PubMed

Liu, Jianmin; Wang, Baoyu; Tai, Chao; Wu, Li; Zhao, Han; Guan, Jiadong; Chen, Linyong

2016-01-01

Bioconversion of coal to methane has gained increased attention in recent decades because of its economic and environmental advantages. However, the mechanism of this process is difficult to study in depth, partly because of difficulties associated with the analysis of intermediates generated in coal bioconversion. In this investigation, we report on an effective method to analyze volatile intermediates generated in the bioconversion of coal under strict anaerobic conditions. We conduct in-situ extraction of intermediates using headspace solid-phase micro-extraction followed by detection by gas chromatography-mass spectrometry. Bioconversion simulation equipment was modified and combined with a solid-phase micro-extraction device. In-situ extraction could be achieved by using the combined units, to avoid a breakdown in anaerobic conditions and to maintain the experiment continuity. More than 30 intermediates were identified qualitatively in the conversion process, and the variation in trends of some typical intermediates has been discussed. Volatile organic acids (C2-C7) were chosen for a quantitative study of the intermediates because of their importance during coal bioconversion to methane. Fiber coating, extraction time, and solution acidity were optimized in the solid-phase micro-extraction procedure. The pressure was enhanced during the bioconversion process to investigate the influence of headspace pressure on analyte extraction. The detection limits of the method ranged from 0.0006 to 0.02 mmol/L for the volatile organic acids and the relative standard deviations were between 4.6% and 11.5%. The volatile organic acids (C2-C7) generated in the bioconversion process were 0.01-1.15 mmol/L with a recovery range from 80% to 105%. The developed method is useful for further in-depth research on the bioconversion of coal to methane.

An Effective Method to Detect Volatile Intermediates Generated in the Bioconversion of Coal to Methane by Gas Chromatography-Mass Spectrometry after In-Situ Extraction Using Headspace Solid-Phase Micro-Extraction under Strict Anaerobic Conditions

PubMed Central

Liu, Jianmin; Wang, Baoyu; Tai, Chao; Wu, Li; Zhao, Han; Guan, Jiadong; Chen, Linyong

2016-01-01

Bioconversion of coal to methane has gained increased attention in recent decades because of its economic and environmental advantages. However, the mechanism of this process is difficult to study in depth, partly because of difficulties associated with the analysis of intermediates generated in coal bioconversion. In this investigation, we report on an effective method to analyze volatile intermediates generated in the bioconversion of coal under strict anaerobic conditions. We conduct in-situ extraction of intermediates using headspace solid-phase micro-extraction followed by detection by gas chromatography-mass spectrometry. Bioconversion simulation equipment was modified and combined with a solid-phase micro-extraction device. In-situ extraction could be achieved by using the combined units, to avoid a breakdown in anaerobic conditions and to maintain the experiment continuity. More than 30 intermediates were identified qualitatively in the conversion process, and the variation in trends of some typical intermediates has been discussed. Volatile organic acids (C2–C7) were chosen for a quantitative study of the intermediates because of their importance during coal bioconversion to methane. Fiber coating, extraction time, and solution acidity were optimized in the solid-phase micro-extraction procedure. The pressure was enhanced during the bioconversion process to investigate the influence of headspace pressure on analyte extraction. The detection limits of the method ranged from 0.0006 to 0.02 mmol/L for the volatile organic acids and the relative standard deviations were between 4.6% and 11.5%. The volatile organic acids (C2–C7) generated in the bioconversion process were 0.01–1.15 mmol/L with a recovery range from 80% to 105%. The developed method is useful for further in-depth research on the bioconversion of coal to methane. PMID:27695055

Effect of dietary protein concentration on ammonia and greenhouse gas emitting potential of dairy manure.

PubMed

Lee, C; Hristov, A N; Dell, C J; Feyereisen, G W; Kaye, J; Beegle, D

2012-04-01

Two experiments were conducted to investigate the effect of dietary crude protein concentration on ammonia (NH(3)) and greenhouse gas (GHG; nitrous oxide, methane, and carbon dioxide) emissions from fresh dairy cow manure incubated in a controlled environment (experiment 1) and from manure-amended soil (experiment 2). Manure was prepared from feces and urine collected from lactating Holstein cows fed diets with 16.7% (DM basis; HCP) or 14.8% CP (LCP). High-CP manure had higher N content and proportion of NH(3)- and urea-N in total manure N than LCP manure (DM basis: 4.4 vs. 2.8% and 51.4 vs. 30.5%, respectively). In experiment 1, NH(3) emitting potential (EP) was greater for HCP compared with LCP manure (9.20 vs. 4.88 mg/m(2) per min, respectively). The 122-h cumulative NH(3) emission tended to be decreased 47% (P=0.09) using LCP compared with HCP manure. The EP and cumulative emissions of GHG were not different between HCP and LCP manure. In experiment 2, urine and feces from cows fed LCP or HCP diets were mixed and immediately applied to lysimeters (61×61×61 cm; Hagerstown silt loam; fine, mixed, mesic Typic Hapludalf) at 277 kg of N/ha application rate. The average NH(3) EP (1.53 vs. 1.03 mg/m(2) per min, respectively) and the area under the EP curve were greater for lysimeters amended with HCP than with LCP manure. The largest difference in the NH(3) EP occurred approximately 24 h after manure application (approximately 3.5 times greater for HCP than LCP manure). The 100-h cumulative NH(3) emission was 98% greater for HCP compared with LCP manure (7,415 vs. 3,745 mg/m(2), respectively). The EP of methane was increased and that of carbon dioxide tended to be increased by LCP compared with HCP manure. The cumulative methane emission was not different between treatments, whereas the cumulative carbon dioxide emission was increased with manure from the LCP diet. Nitrous oxide emissions were low in this experiment and did not differ between treatments. In the conditions of these experiments, fresh manure from dairy cows fed a LCP diet had substantially lower NH(3) EP, compared with manure from cows fed a HCP diet. The LCP manure increased soil methane EP due to a larger mass of manure added to meet plant N requirements compared with HCP manure. These results represent effects of dietary protein on NH(3) and GHG EP of manure in controlled laboratory conditions and do not account for environmental factors affecting gaseous emissions from manure on the farm. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Sublimation systems and associated methods

DOEpatents

Turner, Terry D.; McKellar, Michael G.; Wilding, Bruce M.

2016-02-09

A system for vaporizing and sublimating a slurry comprising a fluid including solid particles therein. The system includes a first heat exchanger configured to receive the fluid including solid particles and vaporize the fluid and a second heat exchanger configured to receive the vaporized fluid and solid particles and sublimate the solid particles. A method for vaporizing and sublimating a fluid including solid particles therein is also disclosed. The method includes feeding the fluid including solid particles to a first heat exchanger, vaporizing the fluid, feeding the vaporized fluid and solid particles to a second heat exchanger and sublimating the solid particles. In some embodiments the fluid including solid particles is liquid natural gas or methane including solid carbon dioxide particles.

Co-digestion of sewage sludge with crude or pretreated glycerol to increase biogas production.

PubMed

Dos Santos Ferreira, Janaína; Volschan, Isaac; Cammarota, Magali Christe

2018-05-23

Anaerobic co-digestion of sewage sludge and glycerol from the biodiesel industry was evaluated in three experimental stages. In the first step, the addition of higher proportions of crude glycerol (5-20% v/v) to the sludge was evaluated, and the results showed a marked decrease in pH and inhibition of methane production. In the second step, co-digestion of sludge with either a lower proportion (1% v/v) of crude glycerol or glycerol pretreated to remove salinity resulted in volatile acid accumulation and low methane production. The accumulation of volatile acids due to the rapid degradation of glycerol in the mixture was more detrimental to methanogenesis than the salinity of the crude glycerol. In the third step, much lower amounts of crude glycerol were added to the sludge (0.3, 0.5, 0.7% v/v), resulting in buffering of the reaction medium and higher methane production than in the control (pure sludge). The best condition for co-digestion was with the addition of 0.5% (v/v) crude glycerol to the sewage sludge, which equals 0.6 g glycerol/g volatile solids applied. Under this condition, the specific methane production (mL CH 4 /g volatile solids applied) was 1.7 times higher than in the control.

On direct internal methane steam reforming kinetics in operating solid oxide fuel cells with nickel-ceria anodes

NASA Astrophysics Data System (ADS)

Thallam Thattai, A.; van Biert, L.; Aravind, P. V.

2017-12-01

Major operating challenges remain to safely operate methane fuelled solid oxide fuel cells due to undesirable temperature gradients across the porous anode and carbon deposition. This article presents an experimental study on methane steam reforming (MSR) global kinetics for single operating SOFCs with Ni-GDC (gadolinium doped ceria) anodes for low steam to carbon (S/C) ratios and moderate current densities. The study points out the hitherto insufficient research on MSR global and intrinsic kinetics for operating SOFCs with complete Ni-ceria anodes. Further, it emphasizes the need to develop readily applicable global kinetic models as a subsequent step from previously reported state-of-art and complex intrinsic models. Two rate expressions of the Power law (PL) and Langmuir-Hinshelwood (LH) type have been compared and based on the analysis, limitations of using previously proposed rate expressions for Ni catalytic beds to study MSR kinetics for complete cermet anodes have been identified. Firstly, it has been shown that methane reforming on metallic (Ni) current collectors may not be always negligible, contrary to literature reports. Both PL and LH kinetic models predict significantly different local MSR reaction rate and species partial pressure distributions along the normalized reactor length, indicating a strong need for further experimental verifications.

Catalytic properties of new anode materials for solid oxide fuel cells operated under methane at intermediary temperature

NASA Astrophysics Data System (ADS)

Sauvet, A.-L.; Fouletier, J.

The recent trend in solid oxide fuel cell concerns the use of natural gas as fuel. Steam reforming of methane is a well-established process for producing hydrogen directly at the anode side. In order to develop new anode materials, the catalytic activities of several oxides for the steam reforming of methane were characterized by gas chromatography. We studied the catalytic activity as a function of steam/carbon ratios r. The methane and the steam content were varied between 5 and 30% and between 1.5 and 3.5%, respectively, corresponding to r-values between 0.07 and 0.7. Catalyst (ruthenium and vanadium)-doped lanthanum chromites substituted with strontium, gadolinium-doped ceria (Ce 0.9Gd 0.1O 2) referred as to CeGdO 2, praseodymium oxide, molybdenum oxide and copper oxide were tested. The working temperature was fixed at 850°C, except for 5% ruthenium-doped La 1- xSr xCrO 3 where the temperature was varied between 700 and 850°C. Two types of behavior were observed as a function of the activity of the catalyst. The higher steam reforming efficiency was observed with 5% of ruthenium above 750°C.

Enhancing Sulfur Tolerance of Ni-Based Cermet Anodes of Solid Oxide Fuel Cells by Ytterbium-Doped Barium Cerate Infiltration.

PubMed

Li, Meng; Hua, Bin; Luo, Jing-Li; Jiang, San Ping; Pu, Jian; Chi, Bo; Li, Jian

2016-04-27

Conventional anode materials for solid oxide fuel cells (SOFCs) are Ni-based cermets, which are highly susceptible to deactivation by contaminants in hydrocarbon fuels. Hydrogen sulfide is one of the commonly existed contaminants in readily available natural gas and gasification product gases of pyrolysis of biomasses. Development of sulfur tolerant anode materials is thus one of the critical challenges for commercial viability and practical application of SOFC technologies. Here we report a viable approach to enhance substantially the sulfur poisoning resistance of a Ni-gadolinia-doped ceria (Ni-GDC) anode through impregnation of proton conducting perovskite BaCe0.9Yb0.1O3-δ (BCYb). The impregnation of BCYb nanoparticles improves the electrochemical performance of the Ni-GDC anode in both H2 and H2S containing fuels. Moreover, more importantly, the enhanced stability is observed in 500 ppm of H2S/H2. The SEM and XPS analysis indicate that the infiltrated BCYb fine particles inhibit the adsorption of sulfur and facilitate sulfur removal from active sites, thus preventing the detrimental interaction between sulfur and Ni-GDC and the formation of cerium sulfide. The preliminary results of the cell with the BCYb+Ni-GDC anode in methane fuel containing 5000 ppm of H2S show the promising potential of the BCYb infiltration approach in the development of highly active and stable Ni-GDC-based anodes fed with hydrocarbon fuels containing a high concentration of sulfur compounds.

Dual-fuel production from restaurant grease trap waste: bio-fuel oil extraction and anaerobic methane production from the post-extracted residue.

PubMed

Kobayashi, Takuro; Kuramochi, Hidetoshi; Maeda, Kouji; Tsuji, Tomoya; Xu, Kaiqin

2014-10-01

An effective way for restaurant grease trap waste (GTW) treatment to generate fuel oil and methane by the combination of physiological and biological processes was investigated. The heat-driven extraction could provide a high purity oil equivalent to an A-grade fuel oil of Japanese industrial standard with 81-93 wt% of extraction efficiency. A post-extracted residue was treated as an anaerobic digestion feedstock, and however, an inhibitory effect of long chain fatty acid (LCFA) was still a barrier for high-rate digestion. From the semi-continuous experiment fed with the residual sludge as a single substrate, it can be concluded that the continuous addition of calcium into the reactor contributed to reducing LCFA inhibition, resulting in the long-term stable operation over one year. Furthermore, the anaerobic reactor performed well with 70-80% of COD reduction and methane productivity under an organic loading rate up to 5.3g-COD/L/d. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bioaugmentation with hydrolytic microbes to improve the anaerobic biodegradability of lignocellulosic agricultural residues.

PubMed

Tsapekos, P; Kougias, P G; Vasileiou, S A; Treu, L; Campanaro, S; Lyberatos, G; Angelidaki, I

2017-06-01

Bioaugmentation with hydrolytic microbes was applied to improve the methane yield of bioreactors fed with agricultural wastes. The efficiency of Clostridium thermocellum and Melioribacter roseus to degrade lignocellulosic matter was evaluated in batch and continuously stirred tank reactors (CSTRs). Results from batch assays showed that C. thermocellum enhanced the methane yield by 34%. A similar increase was recorded in CSTR during the bioaugmentation period; however, at steady-state the effect was noticeably lower (7.5%). In contrast, the bioaugmentation with M. roseus did not promote markedly the anaerobic biodegradability, as the methane yield was increased up to 10% in batch and no effect was shown in CSTR. High-throughput 16S rRNA amplicon sequencing was used to assess the effect of bioaugmentation strategies on bacterial and archaeal populations. The microbial analysis revealed that both strains were not markedly resided into biogas microbiome. Additionally, the applied strategies did not alter significantly the microbial communities. Copyright © 2017 Elsevier Ltd. All rights reserved.

An explanation of the methanogenic pathway for methane production in anaerobic digestion of nitrogen-rich materials under mesophilic and thermophilic conditions.

PubMed

Yin, Dong-Min; Westerholm, Maria; Qiao, Wei; Bi, Shao-Jie; Wandera, Simon M; Fan, Run; Jiang, Meng-Meng; Dong, Ren-Jie

2018-05-18

The impact of temperature on the anaerobic digestion of chicken manure was investigated by studying the process performance and pathway for continuously-fed digesters under mesophilic and thermophilic conditions. The mesophilic digester obtained a 15% higher methane yield compared with the thermophilic digester. Mesophilic and thermophilic digester had free ammonia of 31 and 145 mg/L, respectively. The stable carbon isotope analysis indicated that 41% and 50% of acetate was converted to methane through the syntrophic acetate oxidation and hydrogenotrophic methanogenesis (SAO-HM) pathway under mesophilic and thermophilic conditions, respectively. The genus Pseudomonas represented 10% and 16% under mesophilic and thermophilic conditions, respectively. A high abundance of the methanogens genus Methanoculleus (94% of total methanogens) in mesophilic and the genus Methanothermobacter (96%) in thermophilic digesters indicated they were the main hydrogenotrophic partners in SAO. The present study therefore illustrated that methanogenic pathway shifting, induced by free ammonia, closely correlated to the process performance. Copyright © 2018. Published by Elsevier Ltd.

Reversing methanogenesis to capture methane for liquid biofuel precursors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soo, Valerie W. C.; McAnulty, Michael J.; Tripathi, Arti

Energy from remote methane reserves is transformative; however, unintended release of this potent greenhouse gas makes it imperative to convert methane efficiently into more readily transported biofuels. No pure microbial culture that grows on methane anaerobically has been isolated, despite that methane capture through anaerobic processes is more efficient than aerobic ones. Here we engineered the archaeal methanogen Methanosarcina acetivorans to grow anaerobically on methane as a pure culture and to convert methane into the biofuel precursor acetate. To capture methane, we cloned the enzyme methyl-coenzyme M reductase (Mcr) from an unculturable organism, anaerobic methanotrophic archaeal population 1 (ANME-1) frommore » a Black Sea mat, into M. acetivorans to effectively run methanogenesis in reverse. Starting with low-density inocula, M. acetivorans cells producing ANME-1 Mcr consumed up to 9 ± 1 % of methane (corresponding to 109 ± 12 µmol of methane) after 6 weeks of anaerobic growth on methane and utilized 10 mM FeCl 3 as an electron acceptor. Accordingly, increases in cell density and total protein were observed as cells grew on methane in a biofilm on solid FeCl 3. When incubated on methane for 5 days, high-densities of ANME-1 Mcr-producing M. acetivorans cells consumed 15 ± 2 % methane (corresponding to 143 ± 16 µmol of methane), and produced 10.3 ± 0.8 mM acetate (corresponding to 52 ± 4 µmol of acetate). We further confirmed the growth on methane and acetate production using 13C isotopic labeling of methane and bicarbonate coupled with nuclear magnetic resonance and gas chromatography/mass spectroscopy, as well as RNA sequencing. Lastly, we anticipate that our metabolically-engineered strain will provide insights into how methane is cycled in the environment by Archaea as well as will possibly be utilized to convert remote sources of methane into more easily transported biofuels via acetate.« less

Reversing methanogenesis to capture methane for liquid biofuel precursors

DOE PAGES

Soo, Valerie W. C.; McAnulty, Michael J.; Tripathi, Arti; ...

2016-01-14

Energy from remote methane reserves is transformative; however, unintended release of this potent greenhouse gas makes it imperative to convert methane efficiently into more readily transported biofuels. No pure microbial culture that grows on methane anaerobically has been isolated, despite that methane capture through anaerobic processes is more efficient than aerobic ones. Here we engineered the archaeal methanogen Methanosarcina acetivorans to grow anaerobically on methane as a pure culture and to convert methane into the biofuel precursor acetate. To capture methane, we cloned the enzyme methyl-coenzyme M reductase (Mcr) from an unculturable organism, anaerobic methanotrophic archaeal population 1 (ANME-1) frommore » a Black Sea mat, into M. acetivorans to effectively run methanogenesis in reverse. Starting with low-density inocula, M. acetivorans cells producing ANME-1 Mcr consumed up to 9 ± 1 % of methane (corresponding to 109 ± 12 µmol of methane) after 6 weeks of anaerobic growth on methane and utilized 10 mM FeCl 3 as an electron acceptor. Accordingly, increases in cell density and total protein were observed as cells grew on methane in a biofilm on solid FeCl 3. When incubated on methane for 5 days, high-densities of ANME-1 Mcr-producing M. acetivorans cells consumed 15 ± 2 % methane (corresponding to 143 ± 16 µmol of methane), and produced 10.3 ± 0.8 mM acetate (corresponding to 52 ± 4 µmol of acetate). We further confirmed the growth on methane and acetate production using 13C isotopic labeling of methane and bicarbonate coupled with nuclear magnetic resonance and gas chromatography/mass spectroscopy, as well as RNA sequencing. Lastly, we anticipate that our metabolically-engineered strain will provide insights into how methane is cycled in the environment by Archaea as well as will possibly be utilized to convert remote sources of methane into more easily transported biofuels via acetate.« less

Understanding the impact of cationic polyacrylamide on anaerobic digestion of waste activated sludge.

PubMed

Wang, Dongbo; Liu, Xuran; Zeng, Guangming; Zhao, Jianwei; Liu, Yiwen; Wang, Qilin; Chen, Fei; Li, Xiaoming; Yang, Qi

2018-03-01

Previous investigations showed that cationic polyacrylamide (cPAM), a flocculant widely used in wastewater pretreatment and waste activated sludge dewatering, deteriorated methane production during anaerobic digestion of sludge. However, details of how cPAM affects methane production are poorly understood, hindering deep control of sludge anaerobic digestion systems. In this study, the mechanisms of cPAM affecting sludge anaerobic digestion were investigated in batch and long-term tests using either real sludge or synthetic wastewaters as the digestion substrates. Experimental results showed that the presence of cPAM not only slowed the process of anaerobic digestion but also decreased methane yield. The maximal methane yield decreased from 139.1 to 86.7 mL/g of volatile suspended solids (i.e., 1861.5 to 1187.0 mL/L) with the cPAM level increasing from 0 to 12 g/kg of total suspended solids (i.e., 0-236.7 mg/L), whereas the corresponding digestion time increased from 22 to 26 d. Mechanism explorations revealed that the addition of cPAM significantly restrained the sludge solubilization, hydrolysis, acidogenesis, and methanogenesis processes. It was found that ∼46% of cAPM was degraded in the anaerobic digestion, and the degradation products significantly affected methane production. Although the theoretically biochemical methane potential of cPAM is higher than that of protein and carbohydrate, only 6.7% of the degraded cPAM was transformed to the final product, methane. Acrylamide, acrylic acid, and polyacrylic acid were found to be the main degradation metabolites, and their amount accounted for ∼50% of the degraded cPAM. Further investigations showed that polyacrylic acid inhibited all the solubilization, hydrolysis, acidogenesis, and methanogenesis processes while acrylamide and acrylic acid inhibited the methanogenesis significantly. Copyright © 2017 Elsevier Ltd. All rights reserved.

Does the diurnal pattern of enteric methane emissions from dairy cows change over time?

PubMed

Bell, M J; Craigon, J; Saunders, N; Goodman, J R; Garnsworthy, P C

2018-02-22

Diet manipulation and genetic selection are two important mitigation strategies for reducing enteric methane (CH4) emissions from ruminant livestock. The aim of this study was to assess whether the diurnal pattern of CH4 emissions from individual dairy cows changes over time when cows are fed on diets varying in forage composition. Emissions of CH4 from 36 cows were measured during milking in an automatic (robotic) milking station in three consecutive feeding periods, for a total of 84 days. In Periods 1 and 2, the 36 cows were fed a high-forage partial mixed ration (PMR) containing 75% forage, with either a high grass silage or high maize silage content. In Period 3, cows were fed a commercial PMR containing 69% forage. Cows were offered PMR ad libitum plus concentrates during milking and CH4 emitted by individual cows was sampled during 8662 milkings. A linear mixed model was used to assess differences among cows, feeding periods and time of day. Considerable variation was observed among cows in daily mean and diurnal patterns of CH4 emissions. On average, cows produced less CH4 when fed on the commercial PMR in feeding Period 3 than when the same cows were fed on high-forage diets in feeding Periods 1 and 2. The average diurnal pattern for CH4 emissions did not significantly change between feeding periods and as lactation progressed. Emissions of CH4 were positively associated with dry matter (DM) intake and forage DM intake. It is concluded that if the management of feed allocation remains constant then the diurnal pattern of CH4 emissions from dairy cows will not necessarily alter over time. A change in diet composition may bring about an increase or decrease in absolute emissions over a 24-h period without significantly changing the diurnal pattern unless management of feed allocation changes. These findings are important for CH4 monitoring techniques that involve taking measurements over short periods within a day rather than complete 24-h observations.

Response profiles of enteric methane emissions and lactational performance during habituation to dietary coconut oil in dairy cows.

PubMed

Hollmann, M; Powers, W J; Fogiel, A C; Liesman, J S; Beede, D K

2013-03-01

Dietary coconut oil (CNO) can reduce dry matter intake (DMI), enteric methane (eCH(4)) emissions, and milk fat yield of lactating cows. The goals of this research were to examine responses to different CNO concentrations during the habituation period (34-d) and to evaluate temporal patterns of DMI, eCH(4), and milk fat yield. Treatment diets contained (dry basis): 0.0% (CNO0), 1.3% (CNO1.3), 2.7% (CNO2.7), 3.3% (CNO3.3), or 4.0% CNO (CNO4). In experiment 1, 12 primi- or small secundiparous cows were housed in individual, environmentally controlled rooms and fed CNO0, CNO1.3, CNO2.7, or CNO4. Measurements included DMI, eCH(4), and milk yield and composition. Due to a precipitous drop in DMI (26%), cows fed CNO4 were replaced with cows fed CNO3.3 following d 10. Dietary CNO of 2.7% or more reduced eCH(4) emissions. Reduction was greater with increased CNO and during the first than the second half of the day. Simultaneously, decline in DMI of cows fed CNO2.7, CNO3.3, or CNO4 was increasingly precipitous with increased CNO concentration. Total-tract neutral detergent fiber (NDF) digestibility during wk 5 was reduced in cows fed CNO2.7 or CNO3.3, which in part explained concomitantly reduced eCH(4)/DMI. In addition, milk fat yield was depressed at an increasing rate in cows fed CNO2.7, CNO3.3, and CNO4. In experiment 2, DMI was measured individually in 12 multiparous cows during habituation to CNO0, CNO1.3, CNO2.7, or CNO3.3 for 21 d before relocation to individual, environmentally controlled rooms. Dietary CNO2.7 or CNO3.3 reduced DMI by d 4 and total-tract NDF digestibility during wk 5. Relocation to individual rooms was associated with a 15% reduction in DMI, which was not affected by treatment. Results showed that 2.7% or more dietary CNO reduced eCH(4) and DMI, caused milk fat depression, and decreased NDF digestibility. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Methanogenic community shifts during the transition from sewage mono-digestion to co-digestion of grass biomass.

PubMed

Hardegen, Justus; Latorre-Pérez, Adriel; Vilanova, Cristina; Günther, Thomas; Porcar, Manuel; Luschnig, Olaf; Simeonov, Claudia; Abendroth, Christian

2018-06-06

In this work, liquid and solid fractions of grass biomass were used as co-substrates for anaerobic co-digestion of sewage sludge. The input of grass biomass was increased gradually, and the underlying methanogenic microbiome was assessed by means of microscopy-based cell counting and full-length 16S rRNA gene high-throughput sequencing, proving for the first time the suitability of nanopore-based portable sequencers as a monitoring tool for anaerobic digestion systems. In both cases co-fermentation resulted in an increased number of bacteria and methanogenic archaea. Interestingly, the microbial communities were highly different between solid and liquid-fed batches. Liquid-fed batches developed a more stable microbiome, enriched in Methanosarcina spp., and resulted in higher methanogenic yield. In contrast, solid-fed batches were highly unstable at higher substrate concentrations, and kept Methanosaeta spp. - typically associated to sewage sludge - as the majoritary methanogenic archaea. Copyright © 2018 Elsevier Ltd. All rights reserved.

Use of a portable, automated, open-circuit gas quantification system and the sulfur hexafluoride tracer technique for measuring enteric methane emissions in Holstein cows fed ad libitum or restricted

USDA-ARS?s Scientific Manuscript database

The sulfur hexafluoride tracer technique (SF**6) is a commonly used method for measuring CH**4 enteric emissions in ruminants. Studies using SF**6 have shown large variation in CH**4 emissions data, inconsistencies in CH**4 emissions across studies, and potential methodological errors. Therefore, th...

Rumen and Cecum Microbiomes in Reindeer (Rangifer tarandus tarandus) Are Changed in Response to a Lichen Diet and May Affect Enteric Methane Emissions

PubMed Central

Hagen, Live H.; Ishaq, Suzanne L.; Zamanzadeh, Mirzaman; Wright, André-Denis G.; Pope, Phillip B.; Sundset, Monica A.

2016-01-01

Reindeer (Rangifer tarandus tarandus) are large Holarctic herbivores whose heterogeneous diet has led to the development of a unique gastrointestinal microbiota, essential for the digestion of arctic flora, which may include a large proportion of lichens during winter. Lichens are rich in plant secondary metabolites, which may affect members of the gut microbial consortium, such as the methane-producing methanogenic archaea. Little is known about the effect of lichen consumption on the rumen and cecum microbiotas and how this may affect methanogenesis in reindeer. Here, we examined the effects of dietary lichens on the reindeer gut microbiota, especially methanogens. Samples from the rumen and cecum were collected from two groups of reindeer, fed either lichens (Ld: n = 4), or a standard pelleted feed (Pd: n = 3). Microbial densities (methanogens, bacteria and protozoa) were quantified using quantitative real-time PCR and methanogen and bacterial diversities were determined by 454 pyrosequencing of the 16S rRNA genes. In general, the density of methanogens were not significantly affected (p>0.05) by the intake of lichens. Methanobrevibacter constituted the main archaeal genus (>95% of reads), with Mbr. thaueri CW as the dominant species in both groups of reindeer. Bacteria belonging to the uncharacterized Ruminococcaceae and the genus Prevotella were the dominant phylotypes in the rumen and cecum, in both diets (ranging between 16–38% total sequences). Bacteria belonging to the genus Ruminococcus (3.5% to 0.6%; p = 0.001) and uncharacterized phylotypes within the order Bacteroidales (8.4% to 1.3%; p = 0.027), were significantly decreased in the rumen of lichen-fed reindeer, but not in the cecum (p = 0.2 and p = 0.087, respectively). UniFrac-based analyses showed archaeal and bacterial libraries were significantly different between diets, in both the cecum and the rumen (vegan::Adonis: pseudo-F<0.05). Based upon previous literature, we suggest that the altered methanogen and bacterial profiles may account for expected lower methane emissions from lichen-fed reindeer. PMID:27159387

Early Fattening Lamb Could Mitigate Methane Production-an Example of Climate Smart Livestock Farming System in Indonesia

NASA Astrophysics Data System (ADS)

Purnomoadi, A.

2018-02-01

Ruminants, with a presence of rumen in their digestive tract, will produce methane during his life. Therefore, shortening the rearing period to produce a meat or milk is an alternative to reduce methane emissions. In Indonesia, in the last decades the tendency to slaughter the sheep at young age (around 5 months old) is increasing. This tendency is due to the young sheep (lamb) provide a tender meat and low in fat, as well as a faster in economical return. This study was aimed to evaluate whether shortening (and early age) fattening can reduce methane emissions. Sixteen data from two experimental sheep, each 8 heads of young sheep (aged 3 months old; initial weight 14.32+/- 1.25 kg), and 8 mature sheep (aged 12 m.o.; initial weight 20.65 +/- 1.89 kg) were used in this study. They were fed the pelleted diet formulated to give at least CP 12% and TDN 60% ad libitum. The results showed that the dry matter intake of young sheep was higher than mature sheep (1.33 vs. 1.08 kg), as well as daily gain (156 vs. 83 g/d) and the methane production (41.4vs 36.0 L/d), or methane production per kg daily gain (269 vs 434 L/kg body weight gain), although the production of methane per DMI was similar (32.0 vs 33.5 L/kg DMI). With assumption that sheep commonly weaned at 2 months old at body weight of 10 kg, and was slaughter at 22 kg of body weight, it could be calculated that shortening (and early age) fattening could reduce totally 1,984 L per head and 10 months shortened.

Free nitrous acid pre-treatment of waste activated sludge enhances volatile solids destruction and improves sludge dewaterability in continuous anaerobic digestion.

PubMed

Wei, Wei; Wang, Qilin; Zhang, Liguo; Laloo, Andrew; Duan, Haoran; Batstone, Damien J; Yuan, Zhiguo

2018-03-01

Previous work has demonstrated that pre-treatment of waste activated sludge (WAS) with free nitrous acid (FNA i.e. HNO 2 ) enhances the biodegradability of WAS, identified by a 20-50% increase in specific methane production in biochemical methane potential (BMP) tests. This suggests that FNA pre-treatment would enhance the destruction of volatile solids (VS) in an anaerobic sludge digester, and reduce overall sludge disposal costs, provided that the dewaterability of the digested sludge is not negatively affected. This study experimentally evaluates the impact of FNA pre-treatment on the VS destruction in anaerobic sludge digestion and on the dewaterability of digested sludge, using continuously operated bench-scale anaerobic digesters. Pre-treatment of full-scale WAS for 24 h at an FNA concentration of 1.8 mg NN/L enhanced VS destruction by 17 ± 1% (from 29.2 ± 0.9% to 34.2 ± 1.1%) and increased dewaterability (centrifuge test) from 12.4 ± 0.4% to 14.1 ± 0.4%. Supporting the VS destruction data, methane production increased by 16 ± 1%. Biochemical methane potential tests indicated that the final digestate stability was also improved with a lower potential from FNA treated digestate. Further, a 2.1 ± 0.2 log improvement in pathogen reduction was also achieved. With inorganic solids representing 15-22% of the full-scale WAS used, FNA pre-treatment resulted in a 16-17% reduction in the volume of dewatered sludge for final disposal. This results in significantly reduced costs as assessed by economic analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gas hydrate decomposition recorded by authigenic barite at pockmark sites of the northern Congo Fan

NASA Astrophysics Data System (ADS)

Kasten, Sabine; Nöthen, Kerstin; Hensen, Christian; Spieß, Volkhard; Blumenberg, Martin; Schneider, Ralph R.

2012-12-01

The geochemical cycling of barium was investigated in sediments of pockmarks of the northern Congo Fan, characterized by surface and subsurface gas hydrates, chemosynthetic fauna, and authigenic carbonates. Two gravity cores retrieved from the so-called Hydrate Hole and Worm Hole pockmarks were examined using high-resolution pore-water and solid-phase analyses. The results indicate that, although gas hydrates in the study area are stable with respect to pressure and temperature, they are and have been subject to dissolution due to methane-undersaturated pore waters. The process significantly driving dissolution is the anaerobic oxidation of methane (AOM) above the shallowest hydrate-bearing sediment layer. It is suggested that episodic seep events temporarily increase the upward flux of methane, and induce hydrate formation close to the sediment surface. AOM establishes at a sediment depth where the upward flux of methane from the uppermost hydrate layer counterbalances the downward flux of seawater sulfate. After seepage ceases, AOM continues to consume methane at the sulfate/methane transition (SMT) above the hydrates, thereby driving the progressive dissolution of the hydrates "from above". As a result the SMT migrates downward, leaving behind enrichments of authigenic barite and carbonates that typically precipitate at this biogeochemical reaction front. Calculation of the time needed to produce the observed solid-phase barium enrichments above the present-day depths of the SMT served to track the net downward migration of the SMT and to estimate the total time of hydrate dissolution in the recovered sediments. Methane fluxes were higher, and the SMT was located closer to the sediment surface in the past at both sites. Active seepage and hydrate formation are inferred to have occurred only a few thousands of years ago at the Hydrate Hole site. By contrast, AOM-driven hydrate dissolution as a consequence of an overall net decrease in upward methane flux seems to have persisted for a considerably longer time at the Worm Hole site, amounting to a few tens of thousands of years.

The phase transformation of methane caused by pressure change during its rising from seepage, revealed by video　observation　and acoustic reflection data

NASA Astrophysics Data System (ADS)

Aoyama, D.; Aoyama, C.

2014-12-01

The plume comes out to the surface of the water, and methane is released for low water temperature and low temperature in the Arctic Ocean by the atmosphere. Methane released by the atmosphere is combined with oxygen and becomes carbon dioxide and the water, and the greenhouse effect is higher in 20 times than carbon dioxide. If quantity of the　methane　plume is quantified, I may estimate the quantity of existing methane underground and can estimate the scale of methane melting into it in seawater. The　methane　plume solved in seawater is one element of the carbon cycle. It is important that I elucidate this element in thinking about the carbon cycle of the wide sense.　However, there is not the report that I showed quantitatively how much methane melts into it in seawater a year from the methane plume. Therefore, in this article, I identified an aspect of gush methane as it by the sound data with the fishfinder and by a gush picture of the methane plume. With that in mind, I quantified the quantity of the methane plume. As a result, the following things became clear. The methane hydrate grain to gush out from a gush mouth is a solid at the bottom of the sea direct top. In this sea area, methane of 7.7*104m3 per unit area gushes out. In addition, the sea area where 6.3*106m3 gushed out existed.

An exploration of knowledge, attitudes and advice given by health professionals to parents in Ireland about the introduction of solid foods. A pilot study

PubMed Central

2010-01-01

Background For the purposes of this paper "weaning is defined as the introduction of the first solid foods to infants". Global recommendations by the World Health Organisation (WHO) recommend that all infants be exclusively breast-fed for the first six months of life. No global recommendations have been made for formula fed infants. In Europe it is recommended that weaning foods should be introduced between 18 weeks and 26 weeks regardless of whether infants are breast or formula fed. In the United Kingdom it is recommended that solids be introduced at around six-months for both breast and formula fed infants. In Ireland official guidelines recommend that breast fed infants should be introduced solids at 6 months of age while for formula fed infants the recommendation is for 4 months. The disparity between these global, European, UK and local recommendations may be a source of confusion for parents and health care professional based in Ireland. Emerging evidence suggests that babies in Ireland are given solid foods before the recommended age but there has been little investigation of the weaning advice provided by health professionals. Since community health professionals have routine parent interactions in the pre-weaning and early-weaning period and hence are in a unique position to positively influence parental weaning decisions, this study aimed to explore their knowledge, attitudes and advice practices about weaning. Methods A mixed-methods approach was used for the research, commencing with a multi-disciplinary focus group to guide and develop a questionnaire. Questionnaires were then distributed in a postal survey to General Practitioners (GPs) (n 179), Practice Nurses (PNs) (n 121), Public Health Nurses (PHNs) (n 107) and Community Dieticians (CDs) (n 8). Results The results indicate varying levels of knowledge of official weaning recommendations and a variety of advice practices. CDs and PHNs acknowledged a clear role in providing weaning advice while demonstrating high confidence levels in providing this advice. However, 19% of PNs and 7% of GP respondents did not acknowledge that they have a role in providing weaning advice to parents; even though Health Service Executive (HSE) written literature given to parents states that they should seek information from PNs and GPs. Conclusion Small pockets of misinformation about the introduction of solid foods persist amongst health professionals which may lead to inconsistent advice for parents. Further research is needed. PMID:20409309

Methane–oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification†

PubMed Central

Wang, Zhe; Guo, Min; Baker, Gary A.; Stetter, Joseph R.; Lin, Lu; Mason, Andrew J.

2017-01-01

Current sensor devices for the detection of methane or natural gas emission are either expensive and have high power requirements or fail to provide a rapid response. This report describes an electrochemical methane sensor utilizing a non-volatile and conductive pyrrolidinium-based ionic liquid (IL) electrolyte and an innovative internal standard method for methane and oxygen dual-gas detection with high sensitivity, selectivity, and stability. At a platinum electrode in bis(trifluoromethylsulfonyl)imide (NTf2)-based ILs, methane is electro-oxidized to produce CO2 and water when an oxygen reduction process is included. The in situ generated CO2 arising from methane oxidation was shown to provide an excellent internal standard for quantification of the electrochemical oxygen sensor signal. The simultaneous quantification of both methane and oxygen in real time strengthens the reliability of the measurements by cross-validation of two ambient gases occurring within a single sample matrix and allows for the elimination of several types of random and systematic errors in the detection. We have also validated this IL-based methane sensor employing both conventional solid macroelectrodes and flexible microfabricated electrodes using single- and double-potential step chronoamperometry. PMID:25093213

The impact of compaction and leachate recirculation on waste degradation in simulated landfills.

PubMed

Ko, Jae Hac; Yang, Fan; Xu, Qiyong

2016-07-01

This study investigated the impact of compaction and leachate recirculation on anaerobic degradation of municipal solid waste (MSW) at different methane formation phases. Two stainless steel lysimeters, C1 and C2, were constructed by equipping a hydraulic cylinder to apply pressure load (42kPs) on the MSW. When MSW started to produce methane, C1 was compacted, but C2 was compacted when the methane production rate declined from the peak generation rate. Methane production of C1was inhibited by the compaction and resulted in producing a total of 106L methane (44L/kgVS). However, the compaction in C2 promoted MSW degradation resulting in producing a total of 298L methane (125L/kgVS). The concentrations of volatile fatty acids and chemical oxygen demand showed temporary increases, when pressure load was applied. It was considered that the increased substrate accessibility within MSW by compaction could cause either the inhibition or the enhancement of methane production, depending the tolerability of methanogens on the acidic inhibition. Leachate recirculation also gave positive effects on methane generation from wet waste in the decelerated methanogenic phase by increasing mass transfer and the concentrations of volatile fatty acids. Copyright © 2016 Elsevier Ltd. All rights reserved.

Co-digestion performance of organic fraction of municipal solid waste with leachate: Preliminary studies.

PubMed

Guven, Huseyin; Akca, Mehmet Sadik; Iren, Erol; Keles, Fatih; Ozturk, Izzet; Altinbas, Mahmut

2018-01-01

The main aim of the study was to evaluate the co-digestion performance of OFMSW with different wastes. Leachate, reverse osmosis (RO) concentrate collected from a leachate treatment facility and dewatered sewage sludge taken from a wastewater treatment plant (WWTP) were used for co-digestion in this paper. An extra effort was made to observe the effect of leachate inclusion in the co-digestion. In the study, the mono-digestion of OFMSW, leachate, RO concentrate and sewage sludge as well as digestion of 7 different waste mixtures were carried out for this objective. The experiments were carried out for approximately 50days under mesophilic conditions. The highest methane yield was 785L CH 4 /kg VS added in the reactor, which had only OFMSW. While the methane yield derived from OFMSW was found higher than previous studies, methane yield of leachate was found to be 110L CH 4 /kg VS added , which was lower than findings in the literature. The mono-substrate of OFMSW was followed by the reactor of having waste mixture of leachate+sewage sludge+OFMSW+water (C7) with 391L CH 4 /kg VS added , which was the only combination included water. In order to understand the effect of leachate and water inclusions on co-digestion, two separate waste combinations; leachate+sewage sludge+OFMSW+water (C7) and leachate+sewage sludge+OFMSW (C1) were prepared that had different amounts of leachate but same amounts of other wastes. The methane yield of leachate+sewage sludge+OFMSW+water (C7) indicated that addition of some water instead of leachate could stimulate biogas production. Methane yield of this reactor was found to be 71% higher than the waste combination of leachate+sewage sludge+OFMSW (C1). It could be thought that the high amount of non-biodegradable matters in leachate could be responsible for lower methane yield in leachate+sewage sludge+OFMSW (C1) reactor. Methane yields of the reactors showed that co-digestion of OFMSW and leachate could be a solution not only for treatment of leachate and but also increasing the biogas potential of leachate. Leachate addition could also adjust optimum total solids (TS) content in anaerobic digestion. It was also understood that RO concentrate did not affect the methane yield in a negative way. The similar characterization of leachate and RO concentrate in this study could offer the utilization of RO concentrate instead of leachate. The findings showed that volatile solids (VS) removals were changed from 32% to 61% in the reactors. While the reactor of leachate+RO concentrate+OFMSW (C6) had the highest VS removal, the reactor of the sole substrate leachate had the lowest VS removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of Natural Mineral on Methane Production and Process Stability During Semi-Continuous Mono-Digestion of Maize Straw.

PubMed

González-Suárez, A; Pereda-Reyes, I; Pozzi, E; da Silva, A José; Oliva-Merencio, D; Zaiat, M

2016-04-01

The effect of natural mineral on the mono-digestion of maize straw was evaluated in continuously stirred tank reactors (CSTRs) at 38 °C. Different strategies of mineral addition were studied. The organic loading rate (OLR) was varied from 0.5 to 2.5 g volatile solid (VS) L(-1) d(-1). A daily addition of 1 g mineral L(-1) in reactor 2 (R2) diminished the methane production by about 11 % with respect to the initial phase. However, after a gradual addition of mineral, an average methane yield of 257 NmL CH4 g VS(-1) was reached and the methane production was enhanced by 30 % with regard to R1. An increase in the frequency of mineral addition did not enhance the methane production. The archaeal community was more sensitive to the mineral than the bacterial population whose similarity stayed high between R1 and R2. Significant difference in methane yield was found for both reactors throughout the operation.

Biochemical methane potential from sewage sludge: Effect of an aerobic pretreatment and fly ash addition as source of trace elements.

PubMed

Huiliñir, César; Pinto-Villegas, Paula; Castillo, Alejandra; Montalvo, Silvio; Guerrero, Lorna

2017-06-01

The effect of aerobic pretreatment and fly ash addition on the production of methane from mixed sludge is studied. Three assays with pretreated and not pretreated mixed sludge in the presence of fly ash (concentrations of 0, 10, 25, 50, 250 and 500mg/L) were run at mesophilic condition. It was found that the combined use of aerobic pretreatment and fly ash addition increases methane production up to 70% when the fly ash concentrations were lower than 50mg/L, while concentrations higher than 250mg/L cause up to 11% decrease of methane production. For the anaerobic treatment of mixed sludge without pretreatment, the fly ash improved methane generation at all the concentrations studied, with a maximum of 56%. The removal of volatile solids does not show an improvement compared to the separate use of an aerobic pre-treatment and fly ash addition. Therefore, the combined use of the aerobic pre-treatment and fly ash addition improves only the production of methane. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multiband infrared inversion for low-concentration methane monitoring in a confined dust-polluted atmosphere.

PubMed

Wang, Wenzheng; Wang, Yanming; Song, Wujun; Li, Xueqin

2017-03-20

A multiband infrared diagnostic (MBID) method for methane emission monitoring in limited underground environments was presented considering the strong optical background of gas/solid attenuation. Based on spatial distribution of aerosols and complex refractive index of dust particles, forward calculations were carried out with/without methane to obtain the spectral transmittance through the participating atmosphere in a mine roadway. Considering the concurrent attenuation and absorption behavior of dust and gases, four infrared wavebands were selected to retrieve the methane concentration combined with a stochastic particle swarm optimization (SPSO) algorithm. Inversion results prove that the presented MBID method is robust and effective in identifying methane at concentrations of 0.1% or even lower with inversed relative error within 10%. Further analyses illustrate that the four selected wavebands are indispensable, and the MBID method is still valid with transmission signal disturbance in a conventional dust-polluted atmosphere under mechanized mining condition. However, the effective detection distance should be limited within 50 m to ensure inversed relative error less than 5% at 1% methane concentration.

A Review: Using Pyrolysis and its Bioproducts to Help Close the Loop in Sustainable Life Support Systems

NASA Technical Reports Server (NTRS)

McCoy, LaShelle E.

2013-01-01

The next step in human exploration of space is beyond low Earth orbit and possibly to sites such as the Moon and Mars. Resupply of critical life support components for missions such as these are difficult or impossible. Life support processes for closing the loop of water, oxygen and carbon have to be identified. Currently, there are many technologies proposed for terrestrial missions for waste, water, air processing. and the creation of consumables. There are a variety of different approaches, but few address all of these issues simultaneously. One candidate is pyrolysis; a method where waste streams can be heated in the absence of oxygen to undergo a thermochemical conversion producing a series of bioproducts. Bioproducts like biochar made from non-edible biomass and human solid waste can possibly provide valuable benefits such as waste reduction, regolith fertilization for increased food production, and become a consumable for water processing and air revitalization systems. Syngas containing hydrogen, carbon monoxide and carbon dioxide, can be converted to methane and dimethyl ether to create propellants. Bio-oils can be utilized as a heating fuel or fed to bioreactors that utilize oil-eating microbes.

Effects of inoculum source and co-digestion strategies on anaerobic digestion of residues generated in the treatment of waste vegetable oils.

PubMed

Hidalgo, Dolores; Martín-Marroquín, Jesús M

2014-09-01

This work aims at selecting a suitable strategy to improve the performance of the anaerobic digestion of residues generated in the treatment of waste vegetable oils (WVO). Biochemical methane potential (BMP) assays were conducted at 35 °C to evaluate the effects of substrate mix ratio between a mixture of WVO residues (M) and pig manure (PM) co-digesting by using different inocula. Inoculum from an industrial digester fed with organic waste from hotels, restaurants and catering leftovers (HORECA) showed higher methanogenic activity (55.5 mLCH4 gVS(-1) d(-1)) than municipal wastewater treatment plant (mWWTP) inoculum (42.6 mL CH4 gVS(-1) d(-1)). Furthermore, the results showed that the resistance to WVO residues toxicity was higher for the HORECA sludge than for the mWWTP sludge. HORECA inoculum produced more biogas in all the assays. Moreover, the resulting biogas was of better quality, containing an average of 71.1% (SD = 1.6) methane compared to an average of 69.5% (SD = 1.2) methane for test with mWWTP sludge. The maximum degradation rate occurred at the higher PM mix ratio (M/PM:1/3), reaching 26.7 ± 4.3 mLCH4 gVS(-1) d(-1) for mWWTP inoculum, versus 42.0 ± 1,5 mLCH4 gVS(-1) d(-1) achieved for HORECA inoculum. A high reduction of volatile solids (between 70% and 81%) was obtained with both inocula at all M/PM ratios assayed (1/0, 1/3, 1/1 and 3/1 v/v) but, bearing in mind the operation of a full-scale anaerobic plant, the optimal scenario assayed corresponds to the ratio M/PM: 1/3 v/v where shorter lag periods will make it possible to operate at lower hydraulic retention times. Copyright © 2014 Elsevier Ltd. All rights reserved.

Improving methane yield from organic fraction of municipal solid waste (OFMSW) with magnetic rice-straw biochar.

PubMed

Qin, Yong; Wang, Haoshu; Li, Xiangru; Cheng, Jay Jiayang; Wu, Weixiang

2017-12-01

Magnetic biochar is a potential economical anaerobic digestion (AD) additive. To better understand the possible role of magnetic biochar for the improvement of biomethanization performance and the retention of methanogens, magnetic biochar fabricated under different precursor concentrations were introduced into organic fraction of municipal solid waste (OFMSW) slurry AD system. Results showed that methane production in AD treatment with magnetic biochar fabricated under 3.2g FeCl 3 :100g rice-straw ratio increased by 11.69% compared with control treatment without biochar addition, due to selective enrichment of microorganisms participating in anaerobic digestion on magnetic biochar. AD treatment with magnetic biochar fabricated under 32g FeCl 3 :100g rice-straw ratio resulted in 38.34% decreasement of methane production because of the competition of iron oxide for electron. Furthermore, 25% of total methanogens were absorbed on magnetic biochar and can be harvested with magnet, which can offer a potential solution for preventing the methanogens loss in the anaerobic digesters. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relationship between anaerobic digestion of biodegradable solid waste and spectral characteristics of the derived liquid digestate.

PubMed

Zheng, Wei; Lü, Fan; Phoungthong, Khamphe; He, Pinjing

2014-06-01

The evolution of spectral properties during anaerobic digestion (AD) of 29 types of biodegradable solid waste was investigated to determine if spectral characteristics could be used for assessment of biological stabilization during AD. Biochemical methane potential tests were conducted and spectral indicators (including the ratio of ultraviolet-visible absorbance at 254nm to dissolved organic carbon concentration (SUVA254), the ratio of ultraviolet-visible absorbance measured at 465nm and 665nm (E4/E6), and the abundance of fluorescence peaks) were measured at different AD phases. Inter-relationship between organic degradation and spectral indicators were analyzed by principle component analysis. The results shows that from methane production phase to the end of methane production phase, SUVA254 increased by 0.16-10.93 times, the abundance of fulvic acid-like compounds fluorescence peak increased by 0.01-0.54 times, the abundance of tyrosine fluorescence peak decreased by 0.03-0.64 times. Therefore, these indicators were useful to judge the course of mixed waste digestion. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhanced high-solids anaerobic digestion of waste activated sludge by the addition of scrap iron.

PubMed

Zhang, Yaobin; Feng, Yinghong; Yu, Qilin; Xu, Zibin; Quan, Xie

2014-05-01

Anaerobic digestion of waste activated sludge usually requires pretreatment procedure to improve the bioavailability of sludge, which involves considerable energy and high expenditures. This study proposes a cost-effective method for enhanced anaerobic digestion of sludge without a pretreatment by directly adding iron into the digester. The results showed that addition of Fe(0) powder could enhance 14.46% methane yield, and Fe scrap (clean scrap) could further enhance methane yield (improving rate 21.28%) because the scrap has better mass transfer efficiency with sludge and liquid than Fe(0) powder. The scrap of Fe with rust (rusty scrap) could induce microbial Fe(III) reduction, which resulted in achieving the highest methane yield (improving rate 29.51%), and the reduction rate of volatile suspended solids (VSS) was also highest (48.27%) among Fe powder, clean scrap and rusty scrap. PCR-DGGE proved that the addition of rusty scrap could enhance diversity of acetobacteria and enrich iron-reducing bacteria to enhance degradation of complex substrates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biochemical methane potential of two-phase olive mill solid waste: influence of thermal pretreatment on the process kinetics.

PubMed

Rincón, B; Bujalance, L; Fermoso, F G; Martín, A; Borja, R

2013-07-01

The effect of thermal pretreatment on two-phase olive mill solid waste was evaluated by chemical oxygen demand solubilisation and biochemical methane potential (BMP) tests. Temperatures of 100, 120, 160 and 180°C were applied during 60, 120 and 180 min for each temperature studied. The highest chemical oxygen demand solubilisation after pretreatment (42%) was found for 120 and 180°C during 180 min in both cases. These two conditions were selected for the BMP tests. BMP tests showed two different stages: a first exponential stage and a sigmoidal zone after a lag period. No influence of the pretreatment was observed on the kinetic constant of the first-stage. Clear difference was observed in the maximum methane production rate of the second stage, 76.8 mL CH4/(g VS day) was achieved after pretreatment at 180°C (180 min), value 22% and 40% higher than that obtained for the untreated and pretreated OMSW at 120°C, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Methane hydrate - A major reservoir of carbon in the shallow geosphere?

USGS Publications Warehouse

Kvenvolden, K.A.

1988-01-01

Methane hydrates are solids composed of rigid cages of water molecules that enclose methane. Sediment containing methane hydrates is found within specific pressure-temperature conditions that occur in regions of permafrost and beneath the sea in outer continental margins. Because methane hydrates are globally widespread and concentrate methane within the gas-hydrate structure, the potential amount of methane present in the shallow geosphere at subsurface depths of < ???2000 m is very large. However, estimates of the amount are speculative and range over about three orders of magnitude, from 2 ?? 103 to 4 ?? 106 Gt (gigatons = 1015 g) of carbon, depending on the assumptions made. The estimate I favor is ??? 1 ?? 104 Gt of carbon. The estimated amount of organic carbon in the methane-hydrate reservoir greatly exceeds that in many other reservoirs of the global carbon cycle - for example, the atmosphere (3.6 Gt); terrestrial biota (830 Gt); terrestrial soil, detritus and peat (1960 Gt); marine biota (3 Gt); and marine dissolved materials (980 Gt). In fact, the amount of carbon may exceed that in all fossil fuel deposits (5 ?? 103 Gt). Because methane hydrates contain so much methane and occur in the shallow geosphere, they are of interest as a potential resource of natural gas and as a possible source of atmospheric methane released by global warming. As a potential resource, methane hydrates pose both engineering and production problems. As a contributor to a changing global climate, destabilized methane hydrates, particularly those in shallow, nearshore regions of the Arctic Ocean, may have some effect, but this effect will probably be minimal, at least during the next 100 years. ?? 1988.

Anaerobic slurry co-digestion of poultry manure and straw: effect of organic loading and temperature

PubMed Central

2013-01-01

In order to obtain basic design criteria for anaerobic digestion of a mixture of poultry manure and wheat straw, the effects of different temperatures and organic loading rates on the biogas yield and methane contents were evaluated. Since poultry manure is a poor substrate, in term of the availability of the nutrients, external supplementation of carbon has to be regularly performed, in order to achieve a stable and efficient process. The complete-mix, pilot-scale digester with working volume of 70 L was used. The digestion operated at 25°C, 30°C and 35°C with organic loading rates of 1.0, 2.0, 2.5, 3.0, 3.5 and 4.0 kg Volatile solid/m3d and a HRT of 15 days. At a temperature of 35°C, the methane yield was increased by 43% compared to 25°C. Anaerobic co-digestion appeared feasible with a loading rate of 3.0 kg VS/m3d at 35°C. At this state, the specific methane yield was calculated about 0.12 m3/kg VS with a methane content of 53–70.2% in the biogas. The volatile solid (VS) removal was 72%. As a result of volatile fatty acid accumulation and decrease in pH, when the loading rate was less than 1 or greater than 4 kg VS/m3d, the process was inhibited or overloaded, respectively. Both the lower and higher loading rates resulted in a decline in the methane yield. PMID:24502409

Anaerobic co-digestion of the organic fraction of municipal solid waste with FOG waste from a sewage treatment plant: Recovering a wasted methane potential and enhancing the biogas yield

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin-Gonzalez, L., E-mail: lucia.martin@uab.ca; Colturato, L.F.; Font, X.

2010-10-15

Anaerobic digestion is applied widely to treat the source collected organic fraction of municipal solid wastes (SC-OFMSW). Lipid-rich wastes are a valuable substrate for anaerobic digestion due to their high theoretical methane potential. Nevertheless, although fat, oil and grease waste from sewage treatment plants (STP-FOGW) are commonly disposed of in landfill, European legislation is aimed at encouraging more effective forms of treatment. Co-digestion of the above wastes may enhance valorisation of STP-FOGW and lead to a higher biogas yield throughout the anaerobic digestion process. In the present study, STP-FOGW was evaluated as a co-substrate in wet anaerobic digestion of SC-OFMSWmore » under mesophilic conditions (37 {sup o}C). Batch experiments carried out at different co-digestion ratios showed an improvement in methane production related to STP-FOGW addition. A 1:7 (VS/VS) STP-FOGW:SC-OFMSW feed ratio was selected for use in performing further lab-scale studies in a 5 L continuous reactor. Biogas yield increased from 0.38 {+-} 0.02 L g VS{sub feed}{sup -1} to 0.55 {+-} 0.05 L g VS{sub feed}{sup -1} as a result of adding STP-FOGW to reactor feed. Both VS reduction values and biogas methane content were maintained and inhibition produced by long chain fatty acid (LCFA) accumulation was not observed. Recovery of a currently wasted methane potential from STP-FOGW was achieved in a co-digestion process with SC-OFMSW.« less

Anaerobic co-digestion of the organic fraction of municipal solid waste with FOG waste from a sewage treatment plant: recovering a wasted methane potential and enhancing the biogas yield.

PubMed

Martín-González, L; Colturato, L F; Font, X; Vicent, T

2010-10-01

Anaerobic digestion is applied widely to treat the source collected organic fraction of municipal solid wastes (SC-OFMSW). Lipid-rich wastes are a valuable substrate for anaerobic digestion due to their high theoretical methane potential. Nevertheless, although fat, oil and grease waste from sewage treatment plants (STP-FOGW) are commonly disposed of in landfill, European legislation is aimed at encouraging more effective forms of treatment. Co-digestion of the above wastes may enhance valorisation of STP-FOGW and lead to a higher biogas yield throughout the anaerobic digestion process. In the present study, STP-FOGW was evaluated as a co-substrate in wet anaerobic digestion of SC-OFMSW under mesophilic conditions (37 degrees C). Batch experiments carried out at different co-digestion ratios showed an improvement in methane production related to STP-FOGW addition. A 1:7 (VS/VS) STP-FOGW:SC-OFMSW feed ratio was selected for use in performing further lab-scale studies in a 5L continuous reactor. Biogas yield increased from 0.38+/-0.02 L g VS(feed)(-1) to 0.55+/-0.05 L g VS(feed)(-1) as a result of adding STP-FOGW to reactor feed. Both VS reduction values and biogas methane content were maintained and inhibition produced by long chain fatty acid (LCFA) accumulation was not observed. Recovery of a currently wasted methane potential from STP-FOGW was achieved in a co-digestion process with SC-OFMSW. (c) 2010 Elsevier Ltd. All rights reserved.

Combined mesophilic anaerobic and thermophilic aerobic digestion process for high-strength food wastewater to increase removal efficiency and reduce sludge discharge.

PubMed

Jang, H M; Park, S K; Ha, J H; Park, J M

2014-01-01

In this study, a process that combines the mesophilic anaerobic digestion (MAD) process with thermophilic aerobic digestion (TAD) for high-strength food wastewater (FWW) treatment was developed to examine the removal of organic matter and methane production. All effluent discharged from the MAD process was separated into solid and liquid portions. The liquid part was discarded and the sludge part was passed to the TAD process for further degradation. Then, the digested sludge from the TAD process was recycled back to the MAD unit to achieve low sludge discharge from the combined process. The reactor combination was operated in two phases: during Phase I, 40 d of total hydraulic retention time (HRT) was applied; during Phase II, 20 d was applied. HRT of the TAD process was fixed at 5 d. For a comparison, a control process (single-stage MAD) was operated with the same HRTs of the combined process. Our results indicated that the combined process showed over 90% total solids, volatile solids and chemical oxygen demand removal efficiencies. In addition, the combined process showed a significantly higher methane production rate than that of the control process. Consequently, the experimental data demonstrated that the combined MAD-TAD process was successfully employed for high-strength FWW treatment with highly efficient organic matter reduction and methane production.

Ni modified ceramic anodes for direct-methane solid oxide fuel cells

DOEpatents

Xiao, Guoliang; Chen, Fanglin

2016-01-19

In accordance with certain embodiments of the present disclosure, a method for fabricating a solid oxide fuel cell is described. The method includes synthesizing a composition having a perovskite present therein. The method further includes applying the composition on an electrolyte support to form an anode and applying Ni to the composition on the anode.

Direct use of methane in coal liquefaction

DOEpatents

Sundaram, Muthu S.; Steinberg, Meyer

1987-01-01

This invention relates to a process for converting solid carbonaceous material, such as coal, to liquid and gaseous hydrocarbons utilizing methane, generally at a residence time of about 20-120 minutes at a temperature of 250.degree.-750.degree. C., preferably 350.degree.-450.degree. C., pressurized up to 6000 psi, and preferably in the 1000-2500 psi range, preferably directly utilizing methane 50-100% by volume in a mix of methane and hydrogen. A hydrogen donor solvent or liquid vehicle such as tetralin, tetrahydroquinoline, piperidine, and pyrolidine may be used in a slurry mix where the solvent feed is 0-100% by weight of the coal or carbonaceous feed. Carbonaceous feed material can either be natural, such as coal, wood, oil shale, petroleum, tar sands, etc., or man-made residual oils, tars, and heavy hydrocarbon residues from other processing systems.

Shifting the balance of fermentation products between hydrogen and volatile fatty acids: microbial community structure and function.

PubMed

Miceli, Joseph F; Torres, César I; Krajmalnik-Brown, Rosa

2016-12-01

Fermentation is a key process in many anaerobic environments. Varying the concentration of electron donor fed to a fermenting community is known to shift the distribution of products between hydrogen, fatty acids and alcohols. Work to date has focused mainly on the fermentation of glucose, and how the microbial community structure is affected has not been explored. We fed ethanol, lactate, glucose, sucrose or molasses at 100 me- eq. L -1 , 200 me- eq. L -1 or 400 me- eq. L -1 to batch-fed cultures with fermenting, methanogenic communities. In communities fed high concentrations of electron donor, the fraction of electrons channeled to methane decreased, from 34% to 6%, while the fraction of electrons channeled to short chain fatty acids increased, from 52% to 82%, averaged across all electron donors. Ethanol-fed cultures did not produce propionate, but did show an increase in electrons directed to acetate as initial ethanol concentration increased. In glucose, sucrose, molasses and lactate-fed cultures, propionate accumulation co-occurred with known propionate producing organisms. Overall, microbial communities were determined by the substrate provided, rather than its initial concentration, indicating that a change in community function, rather than community structure, is responsible for shifts in the fermentation products produced. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Producing methane, methanol and electricity from organic waste of fermentation reaction using novel microbes.

PubMed

Dhiman, Saurabh Sudha; Shrestha, Namita; David, Aditi; Basotra, Neha; Johnson, Glenn R; Chadha, Bhupinder S; Gadhamshetty, Venkataramana; Sani, Rajesh K

2018-06-01

Residual solid and liquid streams from the one-pot CRUDE (Conversion of Raw and Untreated Disposal into Ethanol) process were treated with two separate biochemical routes for renewable energy transformation. The solid residual stream was subjected to thermophilic anaerobic digestion (TAD), which produced 95 ± 7 L methane kg -1 volatile solid with an overall energy efficiency of 12.9 ± 1.7%. A methanotroph, Methyloferula sp., was deployed for oxidation of mixed TAD biogas into methanol. The residual liquid stream from CRUDE process was used in a Microbial Fuel Cell (MFC) to produce electricity. Material balance calculations confirmed the integration of biochemical routes (i.e. CRUDE, TAD, and MFC) for developing a sustainable approach of energy regeneration. The current work demonstrates the utilization of different residual streams originated after food waste processing to release minimal organic load to the environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Press fluid pre-treatment optimisation of the integrated generation of solid fuel and biogas from biomass (IFBB) process approach.

PubMed

Corton, John; Toop, Trisha; Walker, Jonathan; Donnison, Iain S; Fraser, Mariecia D

2014-10-01

The integrated generation of solid fuel and biogas from biomass (IFBB) system is an innovative approach to maximising energy conversion from low input high diversity (LIHD) biomass. In this system water pre-treated and ensiled LIHD biomass is pressed. The press fluid is anaerobically digested to produce methane that is used to power the process. The fibrous fraction is densified and then sold as a combustion fuel. Two process options designed to concentrate the press fluid were assessed to ascertain their influence on productivity in an IFBB like system: sedimentation and the omission of pre-treatment water. By concentrating press fluid and not adding water during processing, energy production from methane was increased by 75% per unit time and solid fuel productivity increased by 80% per unit of fluid produced. The additional energy requirements for pressing more biomass in order to generate equal volumes of feedstock were accounted for in these calculations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biohydrogen and methane production via a two-step process using an acid pretreated native microalgae consortium.

PubMed

Carrillo-Reyes, Julian; Buitrón, Germán

2016-12-01

A native microalgae consortium treated under thermal-acidic hydrolysis was used to produce hydrogen and methane in a two-step sequential process. Different acid concentrations were tested, generating hydrogen and methane yields of up to 45mLH 2 gVS -1 and 432mLCH 4 gVS -1 , respectively. The hydrogen production step solubilized the particulate COD (chemical oxygen demand) up to 30%, creating considerable amounts of volatile fatty acids (up to 10gCODL -1 ). It was observed that lower acid concentration presented higher hydrogen and methane production potential. The results revealed that thermal acid hydrolysis of a native microalgae consortium is a simple but effective strategy for producing hydrogen and methane in the sequential process. In addition to COD removal (50-70%), this method resulted in an energy recovery of up to 15.9kJ per g of volatile solids of microalgae biomass, one of the highest reported. Copyright © 2016 Elsevier Ltd. All rights reserved.

Methane production from wheat straw with anaerobic sludge by heme supplementation.

PubMed

Xi, Yonglan; Chang, Zhizhou; Ye, Xiaomei; Xu, Rong; Du, Jing; Chen, Guangyin

2014-11-01

Wheat straw particles were directly used as substrate for batch anaerobic digestion with anaerobic sludge under 35°C to evaluate the effects of adding heme on methane production. When 1mg/l heme was added to the fermentation process with no agitated speed, a maximum cumulative methane production of 12227.8ml was obtained with cumulative methane yield of wheat straw was 257.4ml/g-TS (total solid), which was increased by 20.6% compared with 213.5ml/g-TS of no heme was added in the reactor. Meanwhile, oxido-reduction potential (ORP) level was decreased, the activity of coenzyme F420 was significantly improved and NADH/NAD(+) ratio were the highest than other experimental groups. These results suggest that heme-supplemented anaerobic sludge with no agitated speed may be providing a more reductive environment, which is a cost-effective method of anaerobic digestion from biomass waste to produce methane with less energy consuming. Copyright © 2014 Elsevier Ltd. All rights reserved.

Irradiation Products On Dwarf Planet Makemake

NASA Astrophysics Data System (ADS)

Brown, M. E.; Schaller, E. L.; Blake, G. A.

2015-03-01

The dark, reddish tinged surfaces of icy bodies in the outer solar system are usually attributed to the long term irradiation of simple hydrocarbons leading to the breaking of C-H bonds, loss of hydrogen, and the production of long carbon chains. While the simple hydrocarbon methane is stable and detected on the most massive bodies in the Kuiper Belt, evidence of active irradiation chemistry is scant except for the presence of ethane on methane-rich Makemake and the possible detections of ethane on more methane-poor Pluto and Quaoar. We have obtained deep high signal-to-noise spectra of Makemake from 1.4 to 2.5 μm in an attempt to trace the radiation chemistry in the outer solar system beyond the initial ethane formation. We present the first astrophysical detection of solid ethylene and evidence for acetylene and high-mass alkanes—all expected products of the continued irradiation of methane, and use these species to map the chemical pathway from methane to long-chain hydrocarbons.

A modeling study of methane hydrate decomposition in contact with the external surface of zeolites.

PubMed

Smirnov, Konstantin S

2017-08-30

The behavior of methane hydrate (MH) enclosed between the (010) surfaces of the silicalite-1 zeolite was studied by means of molecular dynamics simulations at temperatures of 150 and 250 K. Calculations reveal that the interaction with the hydrophilic surface OH groups destabilizes the clathrate structure of hydrate. While MH mostly conserves the structure in the simulation at the low temperature, thermal motion at the high temperature breaks the fragilized cages of H-bonded water molecules, thus leading to the release of methane. The dissociation proceeds in a layer-by-layer manner starting from the outer parts of the MH slab until complete hydrate decomposition. The released CH 4 molecules are absorbed by the microporous solid, whereas water is retained at the surfaces of hydrophobic silicalite and forms a meniscus in the interlayer space. Methane uptake reaches 70% of the silicalite sorption capacity. The energy necessary for the endothermic MH dissociation is supplied by the exothermic methane absorption by the zeolite.

Temperature- and pressure-dependent structural transformation of methane hydrates in salt environments

NASA Astrophysics Data System (ADS)

Shin, Donghoon; Cha, Minjun; Yang, Youjeong; Choi, Seunghyun; Woo, Yesol; Lee, Jong-Won; Ahn, Docheon; Im, Junhyuck; Lee, Yongjae; Han, Oc Hee; Yoon, Ji-Ho

2017-03-01

Understanding the stability of volatile species and their compounds under various surface and subsurface conditions is of great importance in gaining insights into the formation and evolution of planetary and satellite bodies. We report the experimental results of the temperature- and pressure-dependent structural transformation of methane hydrates in salt environments using in situ synchrotron X-ray powder diffraction, solid-state nuclear magnetic resonance, and Raman spectroscopy. We find that under pressurized and concentrated brine solutions methane hydrate forms a mixture of type I clathrate hydrate, ice, and hydrated salts. Under a low-pressure condition, however, the methane hydrates are decomposed through a rapid sublimation of water molecules from the surface of hydrate crystals, while NaCl · 2H2O undergoes a phase transition into a crystal growth of NaCl via the migration of salt ions. In ambient pressure conditions, the methane hydrate is fully decomposed in brine solutions at temperatures above 252 K, the eutectic point of NaCl · 2H2O.

More feed efficient sheep produce less methane and carbon dioxide when eating high-quality pellets.

PubMed

Paganoni, B; Rose, G; Macleay, C; Jones, C; Brown, D J; Kearney, G; Ferguson, M; Thompson, A N

2017-09-01

The Australian sheep industry aims to increase the efficiency of sheep production by decreasing the amount of feed eaten by sheep. Also, feed intake is related to methane production, and more efficient (low residual feed intake) animals eat less than expected. So we tested the hypothesis that more efficient sheep produce less methane by investigating the genetic correlations between feed intake, residual feed intake, methane, carbon dioxide, and oxygen. Feed intake, methane, oxygen, and carbon dioxide were measured on Merino ewes at postweaning (1,866 at 223 d old), hogget (1,010 sheep at 607 d old), and adult ages (444 sheep at 1,080 d old). Sheep were fed a high-energy grower pellet ad libitum for 35 d. Individual feed intake was measured using automated feeders. Methane was measured using portable accumulation chambers up to 3 times during this feed intake period. Heritabilities and phenotypic and genotypic correlations between traits were estimated using ASReml. Oxygen (range 0.10 to 0.20) and carbon dioxide (range 0.08 to 0.28) were generally more heritable than methane (range 0.11 to 0.14). Selecting to decrease feed intake or residual feed intake will decrease methane (genetic correlation [] range 0.76 to 0.90) and carbon dioxide ( range 0.65 to 0.96). Selecting to decrease intake ( range 0.64 to 0.78) and methane ( range 0.81 to 0.86) in sheep at postweaning age would also decrease intake and methane in hoggets and adults. Furthermore, selecting for lower residual feed intake ( = 0.75) and carbon dioxide ( = 0.90) in hoggets would also decrease these traits in adults. Similarly, selecting for higher oxygen ( = 0.69) in hoggets would also increase this trait in adults. Given these results, the hypothesis that making sheep more feed efficient will decrease their methane production can be accepted. In addition, carbon dioxide is a good indicator trait for feed intake because it has the highest heritability of the gas traits measured; is cheaper, faster, and easier to measure than feed intake and has strong phenotypic and genetic correlations with feed intake. Furthermore, selection for feed intake, feed efficiency, methane, and carbon dioxide can be done early in sheep at postweaning age or hoggets. This early selection reduces the generation interval for breeding, thereby increasing response to selection.

Assessment of methane generation, oxidation, and emission in a subtropical landfill test cell.

PubMed

Moreira, João M L; Candiani, Giovano

2016-08-01

This paper presents results of a methane balance assessment in a test cell built in a region with a subtropical climate near São Paulo, Brazil. Measurements and calculations were carried out to obtain the total methane emission to the atmosphere, the methane oxidation rate in the cover, and the total methane generation rate in the test cell. The oxidation rate was obtained through a calculation scheme based on a vertical one-dimensional methane transport in the cover region. The measured maximum and mean methane fluxes to the atmosphere were 124.4 and 15.87 g m(-2) d(-1), respectively. The total methane generation rate obtained for the test cell was 0.0380 ± 0.0075 mol s(-1). The results yielded that 69 % of the emitted methane occurred through the central well and 31 % through the cover interface with the atmosphere. The evaluations of the methane oxidation fraction for localized conditions in the lateral embankment of the test cell yielded 0.36 ± 0.11, while for the whole test cell yielded 0.15 ± 0.10. These results conciliate localized and overall evaluations reported in the literature. The specific methane generation rate obtained for the municipal solid waste with an age of 410 days was 317 ± 62 mol year(-1) ton(-1). This result from the subtropical São Paulo region is lower than reported figures for tropical climates and higher than reported figures for temperate climates.

A Combination of Stable Isotope Probing, Illumina Sequencing, and Co-occurrence Network to Investigate Thermophilic Acetate- and Lactate-Utilizing Bacteria.

PubMed

Sun, Weimin; Krumins, Valdis; Dong, Yiran; Gao, Pin; Ma, Chunyan; Hu, Min; Li, Baoqin; Xia, Bingqing; He, Zijun; Xiong, Shangling

2018-01-01

Anaerobic digestion is a complicated microbiological process that involves a wide diversity of microorganisms. Acetate is one of the most important intermediates, and interactions between acetate-oxidizing bacteria and archaea could play an important role in the formation of methane in anoxic environments. Anaerobic digestion at thermophilic temperatures is known to increase methane production, but the effects on the microbial community are largely unknown. In the current study, stable isotope probing was used to characterize acetate- and lactate-oxidizing bacteria in thermophilic anaerobic digestion. In microcosms fed 13 C-acetate, bacteria related to members of Clostridium, Hydrogenophaga, Fervidobacterium, Spirochaeta, Limnohabitans, and Rhodococcus demonstrated elevated abundances of 13 C-DNA fractions, suggesting their activities in acetate oxidation. In the treatments fed 13 C-lactate, Anaeromyxobacter, Desulfobulbus, Syntrophus, Cystobacterineae, and Azospira were found to be the potential thermophilic lactate utilizers. PICRUSt predicted that enzymes related to nitrate and nitrite reduction would be enriched in 13 C-DNA fractions, suggesting that the acetate and lactate oxidation may be coupled with nitrate and/or nitrite reduction. Co-occurrence network analysis indicated bacterial taxa not enriched in 13 C-DNA fractions that may also play a critical role in thermophilic anaerobic digestion.

Process and apparatus for the production of hydrogen by steam reforming of hydrocarbon

DOEpatents

Sircar, Shivaji; Hufton, Jeffrey Raymond; Nataraj, Shankar

2000-01-01

In the steam reforming of hydrocarbon, particularly methane, under elevated temperature and pressure to produce hydrogen, a feed of steam and hydrocarbon is fed into a first reaction volume containing essentially only reforming catalyst to partially reform the feed. The balance of the feed and the reaction products of carbon dioxide and hydrogen are then fed into a second reaction volume containing a mixture of catalyst and adsorbent which removes the carbon dioxide from the reaction zone as it is formed. The process is conducted in a cycle which includes these reactions followed by countercurrent depressurization and purge of the adsorbent to regenerate it and repressurization of the reaction volumes preparatory to repeating the reaction-sorption phase of the cycle.

Solid fossil-fuel recovery by electrical induction heating in situ - A proposal

NASA Astrophysics Data System (ADS)

Fisher, S.

1980-04-01

A technique, termed electrical induction heating, is proposed for in situ processes of energy production from solid fossil fuels, such as bitumen production from underground distillation of oil sand; oil by underground distillation of oil shale; petroleum from heavy oil by underground mobilization of heavy oil, from either residues of conventional liquid petroleum deposits or new deposits of viscous oil; methane and coal tar from lignite and coal deposits by underground distillation of coal; and generation of electricity by surface combustion of low calorific-value gas from underground coke gasification by combustion of the organic residue left from the underground distillation of coal by induction heating. A method of surface distillation of mined coking coal by induction heating to produce coke, methane, and coal tar is also proposed.

An Eco-Friendly Improved Protocol for the Synthesis of Bis(3-indolyl)methanes Using Poly(4-vinylpyridinium)hydrogen Sulfate as Efficient, Heterogeneous, and Recyclable Solid Acid Catalyst

PubMed Central

Banothu, Janardhan; Gali, Rajitha; Velpula, Ravibabu; Bavantula, Rajitha; Crooks, Peter A.

2013-01-01

Highly efficient and eco-friendly protocol for the synthesis of bis(3-indolyl)methanes by the electrophilic substitution reaction of indole with aldehydes catalyzed by poly(4-vinylpyridinium)hydrogen sulfate was described. Excellent yields, shorter reaction times, simple work-up procedure, avoiding hazardous organic solvents, and reusability of the catalyst are the most obvious advantages of this method. PMID:24052864

The construction and operation of a low-cost poultry waste digester.

PubMed

Steinsberger, S C; Shih, J C

1984-05-01

A simple and low-cost poultry waste digester (PWD) was constructed to treat the waste from 4000 caged laying hens on University Research Unit No. 2 at North Carolina State University. The system was built basically of a plastic lining with insulation, a heating system, a hot-water tank, and other metering equipment. It was operated at 50 degrees C and pH 7.5-8.0. The initiation of methane production was achieved using the indigenous microflora in the poultry waste. At an optimal loading rate (7.5 kg volatile solids/m(3) day), the PWD produced biogas (55% methane) at a rate of 4.0 m(3)/m(3) day. The PWD was biologically stable and able to tolerate temporary overloads and shutdowns. A higher loading rate failed to maintain a high gas production rate and caused drops in methane content and pH value. Under optimal conditions, a positive energy balance was demonstrated with a net surplus of 50.6% of the gross energy. For methane production, the PWD system was proved to be technically feasible. The simple design and inexpensive materials used for this model could significantly reduce the cost of digestion compared to more conventional systems. More studies are needed to determine the durability, the required maintenance of the system, and the most economical method of biogas and solid residue utilization.

Remote-Raman and Micro-Raman Studies of Solid CO2, CH4, Gas Hydrates and Ice

NASA Technical Reports Server (NTRS)

Sharma, S. K.; Misra, A. K.; Lucey, P. G.; Exarhos, G. J.; Windisch, C. F., Jr.

2004-01-01

It is well known that on Mars CO2 is the principal constituent of the thin atmosphere and on a seasonal basis CO2 snow and frost coats the polar caps. Also over 25% of the Martian atmosphere freezes out and sublimes again each year. The Mars Odyssey Emission Imaging system (THEMIS) has discovered water ice exposed near the edge of Mars southern perennials cap. In recent years, it has been suggested that in Martian subsurface CO2 may exist as gas hydrate (8CO2 + 44 H2O) with melting temperature of 10C. Since the crust of Mars has been stable for enough time there is also a possibility that methane formed by magmatic processes and/or as a byproduct of anaerobic deep biosphere activity to have raised toward the planet s surface. This methane would have been captured and stored as methane hydrate, which concentrates methane and water. Determination of abundance and distribution of these ices on the surface and in the near surface are of fundamental importance for understanding Martian atmosphere, and for future exploration of Mars. In this work, we have evaluated feasibility of using remote Raman and micro-Raman spectroscopy as potential nondestructive and non-contact techniques for detecting solid CO2, CH4 gas, and gas hydrates as well as water-ice on planetary surfaces.

Genifuel Hydrothermal Processing Bench Scale Technology ...

EPA Pesticide Factsheets

Hydrothermal Liquefaction (HTL) and Catalytic Hydrothermal Gasification (CHG) proof-of-concept bench-scale tests were performed to assess the potential of the Genifuel hydrothermal process technology for handling municipal wastewater sludge. HTL tests were conducted at 300-350◦C and 2900 psig on three different feeds: primary sludge (11.9 wt% solids), secondary sludge (9.7 wt% solids), and post-digester sludge (also referred to as digested solids) (16.0 wt% solids). Corresponding CHG tests were conducted at 350◦C and 2900 psig on the HTL aqueous phase product using a ruthenium based catalyst. A comprehensive analysis of all feed and effluent phases was also performed. Total mass and carbon balances closed to within ± 15% in all but one case. Biocrude yields from HTL tests were 37%, 25%, and 34% for primary sludge, secondary sludge, and digested solids feeds, respectively. The biocrude yields accounted for 59%, 39%, and 49% of the carbon in the feed for primary sludge, secondary sludge, and digested solids feeds, respectively. It should be noted that HTL test results for secondary sludge may have been affected by equipment problems. Biocrude composition and quality were comparable to that seen with biocrudes generated from algae feeds. CHG product gas consisted primarily of methane, with methane yields (relative to CHG input) on a carbon basis of 47%, 61%, and 64% for aqueous feeds that were the product of HTL tests with primary sludge, secondary sludge, and

Archaeal community structure in leachate and solid waste is correlated to methane generation and volume reduction during biodegradation of municipal solid waste.

PubMed

Fei, Xunchang; Zekkos, Dimitrios; Raskin, Lutgarde

2015-02-01

Duplicate carefully-characterized municipal solid waste (MSW) specimens were reconstituted with waste constituents obtained from a MSW landfill and biodegraded in large-scale landfill simulators for about a year. Repeatability and relationships between changes in physical, chemical, and microbial characteristics taking place during the biodegradation process were evaluated. Parameters such as rate of change of soluble chemical oxygen demand in the leachate (rsCOD), rate of methane generation (rCH4), rate of specimen volume reduction (rVt), DNA concentration in the leachate, and archaeal community structures in the leachate and solid waste were monitored during operation. The DNA concentration in the leachate was correlated to rCH4 and rVt. The rCH4 was related to rsCOD and rVt when waste biodegradation was intensive. The structures of archaeal communities in the leachate and solid waste of both simulators were very similar and Methanobacteriaceae were the dominant archaeal family throughout the testing period. Monitoring the chemical and microbial characteristics of the leachate was informative of the biodegradation process and volume reduction in the simulators, suggesting that leachate monitoring could be informative of the extent of biodegradation in a full-scale landfill. Copyright © 2014 Elsevier Ltd. All rights reserved.

Gene network analysis identifies rumen epithelial cell proliferation, differentiation and metabolic pathways perturbed by diet and correlated with methane production

PubMed Central

Xiang, Ruidong; McNally, Jody; Rowe, Suzanne; Jonker, Arjan; Pinares-Patino, Cesar S.; Oddy, V. Hutton; Vercoe, Phil E.; McEwan, John C.; Dalrymple, Brian P.

2016-01-01

Ruminants obtain nutrients from microbial fermentation of plant material, primarily in their rumen, a multilayered forestomach. How the different layers of the rumen wall respond to diet and influence microbial fermentation, and how these process are regulated, is not well understood. Gene expression correlation networks were constructed from full thickness rumen wall transcriptomes of 24 sheep fed two different amounts and qualities of a forage and measured for methane production. The network contained two major negatively correlated gene sub-networks predominantly representing the epithelial and muscle layers of the rumen wall. Within the epithelium sub-network gene clusters representing lipid/oxo-acid metabolism, general metabolism and proliferating and differentiating cells were identified. The expression of cell cycle and metabolic genes was positively correlated with dry matter intake, ruminal short chain fatty acid concentrations and methane production. A weak correlation between lipid/oxo-acid metabolism genes and methane yield was observed. Feed consumption level explained the majority of gene expression variation, particularly for the cell cycle genes. Many known stratified epithelium transcription factors had significantly enriched targets in the epithelial gene clusters. The expression patterns of the transcription factors and their targets in proliferating and differentiating skin is mirrored in the rumen, suggesting conservation of regulatory systems. PMID:27966600

Enhanced bioethanol production by fed-batch simultaneous saccharification and co-fermentation at high solid loading of Fenton reaction and sodium hydroxide sequentially pretreated sugarcane bagasse.

PubMed

Zhang, Teng; Zhu, Ming-Jun

2017-04-01

A study on the fed-batch simultaneous saccharification and co-fermentation (SSCF) of Fenton reaction combined with NaOH pretreated sugarcane bagasse (SCB) at a high solid loading of 10-30% (w/v) was investigated. Enzyme feeding mode, substrate feeding mode and combination of both were compared with the batch mode under respective solid loadings. Ethanol concentrations of above 80g/L were obtained in batch and enzyme feeding modes at a solid loading of 30% (w/v). Enzyme feeding mode was found to increase ethanol productivity and reduce enzyme loading to a value of 1.23g/L/h and 9FPU/g substrate, respectively. The present study provides an economically feasible process for high concentration bioethanol production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Emission factors from small scale appliances burning wood and pellets

NASA Astrophysics Data System (ADS)

Ozgen, Senem; Caserini, Stefano; Galante, Silvia; Giugliano, Michele; Angelino, Elisabetta; Marongiu, Alessandro; Hugony, Francesca; Migliavacca, Gabriele; Morreale, Carmen

2014-09-01

Four manually fed (6-11 kW) firewood burning and two automatic wood pellets (8.8-25 kW) residential heating appliances were tested under real-world operating conditions in order to determine emission factors (EFs) of macropollutants, i.e., carbon monoxide (CO), nitrogen oxides (NOx), non-methane hydrocarbons (NMHC), particulate matter (PM) and trace pollutants such as polycyclic aromatic hydrocarbons (PAH) and dioxins. The results were examined for the influence of different factors (i.e., type of wood, appliance and combustion cycle). The experimental EFs were also compared with the values proposed by the European emission inventory guidebook used in the local inventory in order to evaluate their representativeness of real world emissions. The composite macropollutant EFs for manually fed appliances were: for CO 5858 g GJ-1, for NOx 122 g GJ-1, NMHC 542 g GJ-1, PM 254 g GJ-1, whereas emissions were much lower for automatic pellets appliances: CO 219 g GJ-1, for NOx 66 g GJ-1, NMHC 5 g GJ-1, PM 85 g GJ-1. The highest emissions were generally observed for the open fireplace, however traditional and advanced stoves have the highest overall CO EFs. Especially for the advanced stove real-world emissions are far worse than those measured under cycles used for type testing of residential solid fuel appliances. No great difference is observed for different firewood types in batch working appliances, diversely the quality of the pellets is observed to influence directly the emission performance of the automatic appliances. Benzo(b)fluoranthene is the PAH with the highest contribution (110 mg GJ-1 for manual appliances and 2 mg GJ-1 for automatic devices) followed by benzo(a)pyrene (77 mg GJ-1 for manual appliances and 0.8 mg GJ-1 for automatic devices).

Strategies to achieve high-solids enzymatic hydrolysis of dilute-acid pretreated corn stover.

PubMed

Geng, Wenhui; Jin, Yongcan; Jameel, Hasan; Park, Sunkyu

2015-01-01

Three strategies were presented to achieve high solids loading while maximizing carbohydrate conversion, which are fed-batch, splitting/thickening, and clarifier processes. Enzymatic hydrolysis was performed at water insoluble solids (WIS) of 15% using washed dilute-acid pretreated corn stover. The carbohydrate concentration increased from 31.8 to 99.3g/L when the insoluble solids content increased from 5% to 15% WIS, while the final carbohydrate conversion was decreased from 78.4% to 73.2%. For the fed-batch process, a carbohydrate conversion efficiency of 76.8% was achieved when solid was split into 60:20:20 ratio, with all enzymes added first. For the splitting/thickening process, a carbohydrate conversion of 76.5% was realized when the filtrate was recycled to simulate a steady-state process. Lastly, the clarifier process was evaluated and the highest carbohydrate conversion of 81.4% was achieved. All of these results suggests the possibility of enzymatic hydrolysis at high solids to make the overall conversion cost-competitive. Copyright © 2015 Elsevier Ltd. All rights reserved.

Impact of narasin on manure composition, microbial ecology, and gas emissions from finishing pigs fed either a corn-soybean meal or a corn-soybean meal-dried distillers grains with solubles diets.

PubMed

Kerr, Brian J; Trabue, Steven L; van Weelden, Mark B; Andersen, Daniel S; Pepple, Laura M

2018-04-14

An experiment was conducted to determine the effect of feeding finishing pigs a corn-soybean (CSBM) diet or a CSBM diet supplemented with 30% dried distillers grains with solubles (DDGS), in combination with or without a growth-promoting ionophore (0 or 30 mg narasin/kg of diet), has on manure composition, microbial ecology, and gas emissions. Two separate groups of 24 gilts (initial BW = 145.1 kg, SD = 7.8 kg) were allotted to individual metabolism crates that allowed for total but separate collection of feces and urine during the 48-d collection period. After each of the twice-daily feedings, feces and urine from each crate was collected and added to its assigned enclosed manure storage tank. Each tank contained an individual fan system that pulled a constant stream of air over the manure surface for 2 wk prior to air (day 52) and manure sampling (day 53). After manure sampling, the manure in the tanks was dumped and the tanks cleaned for the second group of pigs. Except for total manure Ca and P output as a percent of intake and for manure methane product rate and biochemical methane potential (P ≤ 0.08), there were no interactions between diet composition and narasin supplementation. Narasin supplementation resulted in increased manure C (P = 0.05), increased manure DM, C, S, Ca, and phosphorus as a percent of animal intake (P ≤ 0.07), and increased manure volatile solids and foaming capacity (P ≤ 0.09). No effect of narasin supplementation was noted on manure VFA concentrations or any of the gas emission parameters measured (P ≥ 0.29). In contrast, feeding finishing pigs a diet containing DDGS dramatically affected manure composition as indicated by increased concentration of DM, C, ammonia, N, and total and volatile solids (P = 0.01), increased manure DM, N, and C as a percent of animal intake (P = 0.01), increased manure total VFA and phenols (P ≤ 0.05), decreased gas emissions of ammonia and volatile sulfur compounds (VSC; P = 0.01), increased emissions of phenols and indoles (P ≤ 0.06), decreased methane production rate (P = 0.01), and slight differences in microbial ecology (R ≤ 0.47). In conclusion, feeding a diet which contains an elevated level of indigestible fiber (i.e., DDGS) resulted in more fiber in the manure which therefore dramatically affected manure composition, gas emissions, and microbial ecology, while narasin supplementation to the diet did not exhibit a significant effect on any of these parameters in the resultant swine manure.

Influence of feedstock-to-inoculum ratio on performance and microbial community succession during solid-state thermophilic anaerobic co-digestion of pig urine and rice straw.

PubMed

Meng, Lingyu; Xie, Li; Kinh, Co Thi; Suenaga, Toshikazu; Hori, Tomoyuki; Riya, Shohei; Terada, Akihiko; Hosomi, Masaaki

2018-03-01

This study investigated the effect of the feedstock-to-inoculum (F/I) ratio on performance of the solid-state anaerobic co-digestion of pig urine and rice straw inoculated with a solid digestate, and clarified the microbial community succession. A 44-day biochemical methane potential test at F/I ratios of 0.5, 1, 2 and 3 at 55 °C and a 35-day large-scale batch test at F/I ratios of 0.5 and 3 at 55 °C were conducted to investigate the effects of F/I ratio on anaerobic digestibility and analyze microbial community succession, respectively. The highest cumulative methane yield was 353.7 m 3 /t VS in the large-scale batch test. Volatile fatty acids did not accumulate at any F/I ratios. The volatile solids reduction rate was highest at a F/I ratio of 0.5. Microbial community structures were similar between F/I ratios of 3 and 0.5, despite differences in digestion performance, suggesting that stable operation can be achieved at these ratios. Copyright © 2017 Elsevier Ltd. All rights reserved.

Different cultivation methods to acclimatise ammonia-tolerant methanogenic consortia.

PubMed

Tian, Hailin; Fotidis, Ioannis A; Mancini, Enrico; Angelidaki, Irini

2017-05-01

Bioaugmentation with ammonia tolerant-methanogenic consortia was proposed as a solution to overcome ammonia inhibition during anaerobic digestion process recently. However, appropriate technology to generate ammonia tolerant methanogenic consortia is still lacking. In this study, three basic reactors (i.e. batch, fed-batch and continuous stirred-tank reactors (CSTR)) operated at mesophilic (37°C) and thermophilic (55°C) conditions were assessed, based on methane production efficiency, incubation time, TAN/FAN (total ammonium nitrogen/free ammonia nitrogen) levels and maximum methanogenic activity. Overall, fed-batch cultivation was clearly the most efficient method compared to batch and CSTR. Specifically, by saving incubation time up to 150%, fed-batch reactors were acclimatised to nearly 2-fold higher FAN levels with a 37%-153% methanogenic activity improvement, compared to batch method. Meanwhile, CSTR reactors were inhibited at lower ammonia levels. Finally, specific methanogenic activity test showed that hydrogenotrophic methanogens were more active than aceticlastic methanogens in all FAN levels above 540mgNH 3 -NL -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

A Single-Culture Bioprocess of Methanothermobacter thermautotrophicus to Upgrade Digester Biogas by CO2-to-CH4 Conversion with H2

PubMed Central

Martin, Matthew R.; Fornero, Jeffrey J.; Angenent, Largus T.

2013-01-01

We optimized and tested a postbioprocessing step with a single-culture archaeon to upgrade biogas (i.e., increase methane content) from anaerobic digesters via conversion of CO2 into CH4 by feeding H2 gas. We optimized a culture of the thermophilic methanogen Methanothermobacter thermautotrophicus using: (1) a synthetic H2/CO2 mixture; (2) the same mixture with pressurization; (3) a synthetic biogas with different CH4 contents and H2; and (4) an industrial, untreated biogas and H2. A laboratory culture with a robust growth (dry weight of 6.4–7.4 g/L; OD600 of 13.6–15.4), a volumetric methane production rate of 21 L/L culture-day, and a H2 conversion efficiency of 89% was moved to an industrial anaerobic digester facility, where it was restarted and fed untreated biogas with a methane content of ~70% at a rate such that CO2 was in excess of the stoichiometric requirements in relation to H2. Over an 8-day operating period, the dry weight of the culture initially decreased slightly before stabilizing at an elevated level of ~8 g/L to achieve a volumetric methane production rate of 21 L/L culture-day and a H2 conversion efficiency of 62%. While some microbial contamination of the culture was observed via microscopy, it did not affect the methane production rate of the culture. PMID:24194675

Nitrate decreases ruminal methane production with slight changes to ruminal methanogen composition of nitrate-adapted steers.

PubMed

Zhao, Liping; Meng, Qingxiang; Li, Yan; Wu, Hao; Huo, Yunlong; Zhang, Xinzhuang; Zhou, Zhenming

2018-03-20

This study was conducted to examine effects of nitrate on ruminal methane production, methanogen abundance, and composition. Six rumen-fistulated Limousin×Jinnan steers were fed diets supplemented with either 0% (0NR), 1% (1NR), or 2% (2NR) nitrate (dry matter basis) regimens in succession. Rumen fluid was taken after two-week adaptation for evaluation of in vitro methane production, methanogen abundance, and composition measurements. Results showed that nitrate significantly decreased in vitro ruminal methane production at 6 h, 12 h, and 24 h (P < 0.01; P < 0.01; P = 0.01). The 1NR and 2NR regimens numerically reduced the methanogen population by 4.47% and 25.82% respectively. However, there was no significant difference observed between treatments. The alpha and beta diversity of the methanogen community was not significantly changed by nitrate either. However, the relative abundance of the methanogen genera was greatly changed. Methanosphaera (P L  = 0.0033) and Methanimicrococcus (P L  = 0.0113) abundance increased linearly commensurate with increasing nitration levels, while Methanoplanus abundance was significantly decreased (P L  = 0.0013). The population of Methanoculleus, the least frequently identified genus in this study, exhibited quadratic growth from 0% to 2% when nitrate was added (P Q  = 0.0140). Correlation analysis found that methane reduction was significantly related to Methanobrevibacter and Methanoplanus abundance, and negatively correlated with Methanosphaera and Methanimicrococcus abundance.

Enhanced activity and stability of La-doped CeO2 monolithic catalysts for lean-oxygen methane combustion.

PubMed

Zhu, Wenjun; Jin, Jianhui; Chen, Xiao; Li, Chuang; Wang, Tonghua; Tsang, Chi-Wing; Liang, Changhai

2018-02-01

Effective utilization of coal bed methane is very significant for energy utilization and environment protection. Catalytic combustion of methane is a promising way to eliminate trace amounts of oxygen in the coal bed methane and the key to this technology is the development of high-efficiency catalysts. Herein, we report a series of Ce 1-x La x O 2-δ (x = 0-0.8) monolithic catalysts for the catalytic combustion of methane, which are prepared by citric acid method. The structural characterization shows that the substitution of La enhance the oxygen vacancy concentration and reducibility of the supports and promote the migration of the surface oxygen, as a result improve the catalytic activity of CeO 2 . M-Ce 0.8 La 0.2 O 2-δ (monolithic catalyst, Ce 0.8 La 0.2 O 2-δ coated on cordierite honeycomb) exhibits outstanding activity for methane combustion, and the temperature for 10 and 90% methane conversion are 495 and 580 °C, respectively. Additionally, Ce 0.8 La 0.2 O 2-δ monolithic catalyst presents excellent stability at high temperature. These Ce 1-x La x O 2-δ monolithic materials with a small amount of La incorporation therefore show promises as highly efficient solid solution catalysts for lean-oxygen methane combustion. Graphical abstract ᅟ.

Geology beneath and beside the notorious Payatas open dump, Metro Manila, Philippines

NASA Astrophysics Data System (ADS)

Tomarong, C.; Arcilla, C.; de Sales, L.; Chua, S.; Garcia, E.; Pamintuan, G.

2003-04-01

With a minimum of 6000 tonnes/day municipal waste output, and with NO existing operational sanitary landfill and with incineration illegal, Metro Manila has a very serious solid waste disposal problem. Unsorted municipal waste are being piled in open dumps, the most notorious of which is the Payatas open dump. A recent, tragic garbage-slide in this open dump caused dozens of deaths, news of which were broadcast internationally. Political expediency laced with a lot of corruption, rather than sound science, was the main basis for selecting this site as an open dump. As an example, this dump is situated < 1 km from the Novaliches Watershed Reservation, one of the main sources of drinking water for Metro Manila’s 12 million population! Yet, after dumping operations that have lasted more than 10 years, only recently were the preliminary geologic studies begun. Payatas is not a designed landfill and its untreated leachate is openly polluting the headwaters of the Marikina and Pasig Rivers. In addition, during the summer months, there is always the constant threat of fire due to methane induced burning from the dump, aside from the aerial pollution from dioxins and furans derived from incomplete combustion of municipal solid waste. With limited funding from the Quezon City government, a feasibility study was conducted to assess the methane generation potential of Payatas. This interdisciplinary study comprised bedrock geological studies, topographic mapping of the dump, drilling of the dump to obtain stratigraphic solid waste samples for waste characterization, laying of horizontal methane and dewatering pipes, and preliminary methane flow studies. The waste characterization has highlighted the unusually high organic (especially yard waste) component of the solid waste dumped at Payatas. Waste characterization shows that a significant portion of the waste is plastics. Several cross-sections cut across the dump show that the side slopes of the dump are on the average steeper than the pre-dump slopes. The “bedrock” of the Payatas dump are conglomerate members of the Pleistocene volcaniclastic Guadualupe Formation. Studies are still to be done on the extent of pollution on surface and groundwater in the Payatas environs.

Advanced Development of a Compact 5-15 lbf Lox/Methane Thruster for an Integrated Reaction Control and Main Engine Propulsion System

NASA Technical Reports Server (NTRS)

Hurlbert, Eric A.; McManamen, John Patrick; Sooknanen, Josh; Studak, Joseph W.

2011-01-01

This paper describes the advanced development and testing of a compact 5 to 15 lbf LOX/LCH4 thruster for a pressure-fed integrated main engine and RCS propulsion system to be used on a spacecraft "vertical" test bed (VTB). The ability of the RCS thruster and the main engine to operate off the same propellant supply in zero-g reduces mass and improves mission flexibility. This compact RCS engine incorporates several features to dramatically reduce mass and parts count, to ease manufacturing, and to maintain acceptable performance given that specific impulse (Isp) is not the driver. For example, radial injection holes placed on the chamber body for easier drilling, and high temperature Haynes 230 were selected for the chamber over other more expensive options. The valve inlets are rotatable before welding allowing different orientations for vehicle integration. In addition, the engine design effort selected a coil-on-plug ignition system which integrates a relay and coil with the plug electrode, and moves some exciter electronics to avionics driver board. The engine injector design has small dribble volumes to target minimum pulse widths of 20 msec. and an efficient minimum impulse bit of less than 0.05 lbf-sec. The propellants, oxygen and methane, were chosen because together they are a non-toxic, Mars-forward, high density, space storable, and high performance propellant combination that is capable of pressure-fed and pump-fed configurations and integration with life support and power subsystems. This paper will present the results of the advanced development testing to date of the RCS thruster and the integration with a vehicle propulsion system.

Nutritional evaluation of structured lipid containing omega 6 fatty acid synthesized from coconut oil in rats.

PubMed

Rao, Reena; Lokesh, Belur R

2003-06-01

Coconut oil is rich in medium chain fatty acids, but deficient in polyunsaturated fatty acids (PUFA). Structured lipids (SL) enriched with omega 6 PUFA were synthesized from coconut oil triglycerides by employing enzymatic acidolysis with free fatty acids obtained from safflower oil. Rats were fed a diet containing coconut oil, coconut oil-safflower oil blend (1:0.7 w/ w) or structured lipid at 10% levels for a period of 60 days. The SL lowered serum cholesterol levels by 10.3 and 10.5% respectively in comparison with those fed coconut oil and blended oil. Similarly the liver cholesterol levels were also decreased by 35.9 and 26.6% respectively in animals fed structured lipids when compared to those fed on coconut oil or the blended oil. Most of the decrease observed in serum cholesterol levels of animals fed structured lipids was found in LDL fraction. The triglyceride levels in serum showed a decrease by 17.5 and 17.4% while in the liver it was reduced by 45.8 and 23.5% in the structured lipids fed animals as compared to those fed coconut oil or blended oil respectively. Differential scanning calorimetric studies indicated that structured lipids had lower melting points and solid fat content when compared to coconut oil or blended oils. These studies indicated that enrichment of coconut oil triglycerides with omega 6 fatty acids lowers its solid fat content. The omega 6 PUFA enriched structured lipids also exhibited hypolipidemic activity.

Effects of titanium dioxide and zinc oxide nanoparticles on methane production from anaerobic co-digestion of primary and excess sludge.

PubMed

Zheng, Xiong; Wu, Lijuan; Chen, Yinguang; Su, Yinglong; Wan, Rui; Liu, Kun; Huang, Haining

2015-01-01

Anaerobic co-digestion of primary and excess sludge is regarded as an efficient way to reuse sludge organic matter to produce methane. In this study, short-term and long-term exposure experiments were conducted to investigate the possible effects of titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) on methane production from anaerobic co-digestion of primary and excess sludge. The data showed that TiO2 NPs had no measurable impact on methane production, even at a high concentration (150 mg/g total suspended solids (TSS)). However, short-term (8 days) exposure to 30 or 150 mg/g-TSS of ZnO NPs significantly decreased methane production. More importantly, these negative effects of ZnO NPs on anaerobic sludge co-digestion were not alleviated by increasing the adaptation time to 105 days. Further studies indicated that the presence of ZnO NPs substantially decreased the abundance of methanogenic archaea, which reduced methane production. Meanwhile, the activities of some key enzymes involved in methane production, such as protease, acetate kinase, and coenzyme F420, were remarkably inhibited by the presence of ZnO NPs, which was also an important reason for the decreased methane production. These results provide a better understanding of the potential risks of TiO2 and ZnO NPs to methane production from anaerobic sludge co-digestion.

Pretreatment of Cottage Cheese to Enhance Biogas Production

PubMed Central

Salgaonkar, Bhakti; Mutnuri, Srikanth

2014-01-01

This study evaluated the possibility of pretreating selected solid fraction of an anaerobic digester treating food waste to lower the hydraulic retention time and increase the methane production. The study investigated the effect of different pretreatments (thermal, chemical, thermochemical and enzymatic) for enhanced methane production from cottage cheese. The most effective pretreatments were thermal and enzymatic. Highest solubilisation of COD was observed in thermal pretreatment, followed by thermochemical. In single enzyme systems, lipase at low concentration gave significantly higher methane yield than for the experiments without enzyme additions. The highest lipase dosages decreased methane yield from cottage cheese. However, in case of protease enzyme an increase in concentration of the enzyme showed higher methane yield. In the case of mixed enzyme systems, pretreatment at 1 : 2 ratio of lipase : protease showed higher methane production in comparison with 1 : 1 and 2 : 1 ratios. Methane production potentials for different pretreatments were as follows: thermal 357 mL/g VS, chemical 293 mL/g VS, and thermochemical 441 mL/g VS. The average methane yield from single enzyme systems was 335 mL/g VS for lipase and 328 mL/g VS for protease. Methane potentials for mixed enzyme ratios were 330, 360, and 339 mL/g VS for 1 : 1, 1 : 2, and 2 : 1 lipase : protease, respectively. PMID:24995288

Evidence of Sulfate-Dependent Anaerobic Methane Oxidation within an Area Impacted by Coalbed Methane-Related Gas Migration

NASA Astrophysics Data System (ADS)

Wolfe, A. L.; Wikin, R. T.

2017-12-01

We evaluated water quality characteristics in the northern Raton Basin of Colorado and documented the response of the Poison Canyon aquifer system several years after upward migration of methane gas occurred from the deeper Vermejo Formation coalbed production zone. Over a 17-month study period, water samples were obtained from domestic water wells and monitoring wells located within the impacted area, and analyzed for 245 constituents, including organic compounds, nutrients, major and trace elements, dissolved gases, and isotopic tracers for carbon, sulfur, oxygen, and hydrogen. Multiple lines of evidence suggest that sulfate-dependent methane biodegradation, which involves the oxidation of methane (CH4) to carbon dioxide (CO2) using sulfate (SO42-) as the terminal electron acceptor, is occurring: (i) consumption of methane and sulfate and production of sulfide and bicarbonate, (ii) methane loss coupled to production of higher molecular weight (C2+) gaseous hydrocarbons, (iii) patterns of 13C enrichment and depletion in methane and dissolved inorganic carbon, and (iv) a systematic shift in sulfur and oxygen isotope ratios of sulfate, indicative of microbial sulfate reduction. Groundwater-methane attenuation is linked to the production of dissolved sulfide, and elevated dissolved sulfide concentrations represent an undesirable secondary water quality impact. The biogeochemical response of the aquifer system has not mobilized naturally occurring trace metals, including arsenic, chromium, cobalt, nickel, and lead, likely due to the microbial production of hydrogen sulfide, which favors stabilization of metals in aquifer solids.

Ensiling of seaweed for a seaweed biofuel industry.

PubMed

Herrmann, Christiane; FitzGerald, Jamie; O'Shea, Richard; Xia, Ao; O'Kiely, Pádraig; Murphy, Jerry D

2015-11-01

Effective biogas production from seaweed necessitates harvest at times of peak quality of biomass and low-loss preservation for year-around supply. Ensiling of five seaweed species and storage up to 90days was investigated as a method to preserve the methane yield potential. Adequate acidification by natural lactic acid fermentation was difficult due to low rapidly fermentable carbohydrate contents, high buffering capacities and low initial numbers of lactic acid bacteria. Nevertheless, products of silage fermentation increased methane yields by up to 28% and compensated for volatile solid losses during ensiling. Preservation of the original methane yield potential was achieved for four of five seaweed species, provided that silage effluent is collected and utilised. 10-28% of the ensiled biomass was released as effluent with methane yields of 218-423LNkg(-1) VS. If further optimised, ensiling represents an effective method of preservation crucial for an efficient seaweed biofuel industry. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of an advanced anaerobic digester design and a kinetic model for biogasification of water hyacinth/sludge blends

DOE Office of Scientific and Technical Information (OSTI.GOV)

Srivastava, V.; Fannin, K.F.; Biljetina, R.

1986-07-01

The Institute of Gas Technology (IGT) conducted a comprehensive laboratory-scale research program to develop and optimize the anaerobic digestion process for producing methane from water hyacinth and sludge blends. This study focused on digester design and operating techniques, which gave improved methane yields and production rates over those observed using conventional digesters. The final digester concept and the operating experience was utilized to design and operate a large-scale experimentla test unit (ETU) at Walt Disney World, Florida. This paper describes the novel digester design, operating techniques, and the results obtained in the laboratory. The paper also discusses a kinetic modelmore » which predicts methane yield, methane production rate, and digester effluent solids as a function of retention time. This model was successfully utilized to predict the performance of the ETU. 15 refs., 6 figs., 6 tabs.« less

Direct use of methane in coal liquefaction

DOEpatents

Sundaram, M.S.; Steinberg, M.

1985-06-19

This invention relates to a process for converting solid carbonaceous material, such as coal, to liquid and gaseous hydrocarbons utilizing methane, generally at a residence time of about 20 to 120 minutes at a temperature of 250 to 750/sup 0/C, preferably 350 to 450/sup 0/C, pressurized up to 6000 psi, and preferably in the 1000 to 2500 psi range, preferably directly utilizing methane 50 to 100% by volume in a mix of methane and hydrogen. A hydrogen donor solvent or liquid vehicle such as tetralin, tetrahydroquinoline, piperidine, and pyrolidine may be used in a slurry mix where the solvent feed is 0 to 100% by weight of the coal or carbonaceous feed. Carbonaceous feed material can either be natural, such as coal, wood, oil shale, petroleum, tar sands, etc., or man-made residual oils, tars, and heavy hydrocarbon residues from other processing systems. 1 fig.

Microalgae to biofuels: life cycle impacts of methane production of anaerobically digested lipid extracted algae.

PubMed

Quinn, Jason C; Hanif, Asma; Sharvelle, Sybil; Bradley, Thomas H

2014-11-01

This study presents experimental measurements of the biochemical methane production for whole and lipid extracted Nannochloropsis salina. Results show whole microalgae produced 430 cm(3)-CH4 g-volatile solids(-1) (g-VS) (σ=60), 3 times more methane than was produced by the LEA, 140 cm(3)-CH4 g-VS(-1) (σ=30). Results illustrate current anaerobic modeling efforts in microalgae to biofuel assessments are not reflecting the impact of lipid removal. On a systems level, the overestimation of methane production is shown to positively skew the environmental impact of the microalgae to biofuels process. Discussion focuses on a comparison results to those of previous anaerobic digestion studies and quantifies the corresponding change in greenhouse gas emissions of the microalgae to biofuels process based on results from this study. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mechanical instability of monocrystalline and polycrystalline methane hydrates

PubMed Central

Wu, Jianyang; Ning, Fulong; Trinh, Thuat T.; Kjelstrup, Signe; Vlugt, Thijs J. H.; He, Jianying; Skallerud, Bjørn H.; Zhang, Zhiliang

2015-01-01

Despite observations of massive methane release and geohazards associated with gas hydrate instability in nature, as well as ductile flow accompanying hydrate dissociation in artificial polycrystalline methane hydrates in the laboratory, the destabilising mechanisms of gas hydrates under deformation and their grain-boundary structures have not yet been elucidated at the molecular level. Here we report direct molecular dynamics simulations of the material instability of monocrystalline and polycrystalline methane hydrates under mechanical loading. The results show dislocation-free brittle failure in monocrystalline hydrates and an unexpected crossover from strengthening to weakening in polycrystals. Upon uniaxial depressurisation, strain-induced hydrate dissociation accompanied by grain-boundary decohesion and sliding destabilises the polycrystals. In contrast, upon compression, appreciable solid-state structural transformation dominates the response. These findings provide molecular insight not only into the metastable structures of grain boundaries, but also into unusual ductile flow with hydrate dissociation as observed during macroscopic compression experiments. PMID:26522051

Methane production by anaerobic digestion of Bermuda grass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klass, D.L.; Ghosh, S.

1979-01-01

Bermuda grass (Cynodon dactylon) is one of the high-yield warm-season grasses that has been suggested as a promising raw material for conversion to methane. Experimental work performed with laboratory digesters to study the anaerobic digestion of Coastal Bermuda grass harvested in Louisiana and having a C/N ratio of 24 is described. Methane yields of about 1.9 SCF/lb of volatile solids( VS) added were observed under conventional mesophilic high-rate conditions. When supplemental nitrogen additions were made, the yields increased up to 3.5 SCF/lb of VS added indicating that the nitrogen content of the grass examined was insufficient to sustain high-rate digestionmore » at the higher yield level. Thermophilic digestion with supplemental nitrogen additions afforded methane yields of about 2.7 SCF/lb VS added. Carbon and energy balances were calculated and the relative biodegradabilities of the organics were estimated.« less

Development of a carbon formation reactor for carbon dioxide reduction

NASA Technical Reports Server (NTRS)

Noyes, G.

1985-01-01

Applied research, engineering development, and performance evaluation were conducted on a process for formation of dense carbon by pyrolysis of methane. Experimental research showed that dense (0.7 to 1.6 g/cc bulk density and 1.6 to 2.2 g/cc solid density) carbon can be produced by methane pyrolysis in quartzwool-packed quartz tubes at temperatrues of 1100 to 1300 C. This result supports the condensation theory of pyrolytic carbon formation from gaseous hydrocarbons. A full-scale Breadboard Carbon Formation Reactor (CFR) was designed, fabricated, and tested at 1100 to 1200 C with 380 to 2280 sccm input flows of methane. Single-pass conversion of methane to carbon ranged from 60 to 100 percent, with 89 percent average conversion. Performance was projected for an Advanced Carbon Reactor Subsystem (ACRS) which indicated that the ACRS is a viable option for management of metabolic carbon on long-duration space missions.

Effect of temperature on methanogenesis stage of two-stage anaerobic digestion of palm oil mill effluent (POME) into biogas

NASA Astrophysics Data System (ADS)

Trisakti, B.; Irvan, Mahdalena; Taslim; Turmuzi, M.

2017-06-01

This study aimed to determine the effect of temperature on methanogenesis stage of conversion of palm oil mill effluent into biogas. Methanogenesis is the second stage of methanogenic anaerobic digestion. Improved performance of the methanogenesis process was determined by measuring the growth of microorganisms, degradation of organic materials, biogas production and composition. Initially, the suitable loading up was determined by varying the HRT 100, 40, 6, and 4.0 days in the continuous stirred tank reactor (CSTR) with mixing rate 100 rpm, pH 6.7-7.5 at room temperature. Next, effect of temperature on the process was determined by varying temperature at mesophilic range (30-42°C) and thermophilic range (43-55°C). Analysis of total solids (TS), volatile solids (VS), total suspended solids (TSS), volatile suspended solids (VSS), and chemical oxygen demand (COD) were conducted in order to study the growth of microorganisms and their abilities in converting organic compound to produce biogas. Degradation of organic content i.e. VS decomposition and COD removal increased with the increasing of temperature. At mesophilic range, VS decomposition and COD removal were 51.56 ± 8.30 and 79.82 ± 6.03, respectively. Meanwhile at thermopilic range, VS decomposition and COD removal were 67.44 ± 3.59 and 79.16 ± 1.75, respectively. Biogas production and its methane content also increased with the increasing of temperature, but CO2 content also increased. Biogas production at mesophilic range was 31.77 ± 3.46 L/kg-ΔVS and methane content was 75 . Meanwhile, biogas production at thermopilic range was 37.03 ± 5.16 L/kg-ΔVS and methane content was 62.25 ± 5.50 .

Influence of pretreatment with Fenton's reagent on biogas production and methane yield from lignocellulosic biomass.

PubMed

Michalska, Karina; Miazek, Krystian; Krzystek, Liliana; Ledakowicz, Stanisław

2012-09-01

Biomass from Miscanthus giganteus, Sida hermaphrodita and Sorghum Moensch was treated with Fenton's reagent for 2 hours under optimal conditions (pH=3, mass ratio of [Fe(2+)]:[H(2)O(2)] equals 1:25 for Miscanthus and Sorghum and 1:15 for Sida). The degrees of delignification were 30.3%, 62.3% and 48.1% for the three plant species, respectively. The volatile fatty acids concentration after chemical pretreatment was high enough for production of biogas with a high methane content. Combined chemical oxidation and enzymatic hydrolysis with cellulase and cellobiase led to glucose contents of above 4 g/L. Among the tested plants, the highest biogas production (25.2 Ndm(3)/kg TS fed) with a 75% methane content was obtained with Sorghum Moensch. The results of the three-step process of biomass degradation show the necessity of applying a chemical pretreatment such as oxidation with Fenton's reagent. Moreover, the coagulation of residual Fe(3+) ions is not required for high biogas production. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of sole or combined administration of nitrate and 3-nitro-1-propionic acid on fermentation and Salmonella survivability in alfalfa-fed rumen cultures in vitro.

PubMed

Correa, Alejandro Castañeda; Trachsel, Julian; Allen, Heather K; Corral-Luna, Agustin; Gutierrez-Bañuelos, Hector; Ochoa-Garcia, Pedro Antonia; Ruiz-Barrera, Oscar; Hume, Michael E; Callaway, Todd R; Harvey, Roger B; Beier, Ross C; Anderson, Robin C; Nisbet, David J

2017-04-01

Ruminal methanogenesis is a digestive inefficiency resulting in the loss of dietary energy consumed by the host and contributing to environmental methane emission. Nitrate is being investigated as a feed supplement to reduce rumen methane emissions but safety and efficacy concerns persist. To assess potential synergies of co-administering sub-toxic amounts of nitrate and 3-nitro-1-propionate (NPA) on fermentation and Salmonella survivability with an alfalfa-based diet, ruminal microbes were cultured with additions of 8 or 16mM nitrate, 4 or 12mM NPA or their combinations. All treatments decreased methanogenesis compared to untreated controls but volatile fatty acid production and fermentation of hexose were also decreased. Nitrate was converted to nitrite, which accumulated to levels inhibitory to digestion. Salmonella populations were enriched in nitrate only-treated cultures but not in cultures co- or solely treated with NPA. These results reveal a need for dose optimization to safely reduce methane production with forage-based diets. Published by Elsevier Ltd.

Anaerobic digestion for treatment of stillage from cellulosic bioethanol production.

PubMed

Tian, Zhuoli; Mohan, Gayathri Ram; Ingram, Lonnie; Pullammanappallil, Pratap

2013-09-01

Thermophilic anaerobic digestion of stillage from a cellulosic ethanol process that uses sugarcane bagasse as feedstock was investigated. A biochemical methane potential (BMP) of 200 ml CH4 at STP (g VS)(-1) was obtained. The whole stillage was separated into two fractions: a fraction retained on 0.5 mm screen called residue and a fraction passing through 0.5 mm screen called filtrate. About 70% of total methane yield of stillage was produced from the filtrate. The filtrate was anaerobically digested in a 15 L semi-continuously fed digester operated for 91 days at HRTs of 21 and 14 days and organic loading rate (OLR) of 1.85 and 2.39 g COD L(-1) d(-1). The methane yield from the stillage from the digester was about 90% of the yield from the BMP assays. The influent soluble COD (sCOD) was reduced from between 35.4 and 38.8 g COD (L(-1)) to between 7.5 and 8 g COD (L(-1)). Copyright © 2013 Elsevier Ltd. All rights reserved.

Influence of AOM on iron-sulfur-carbon systematics in marine sediment: A study from Krishna-Godavari basin, Bay of Bengal

NASA Astrophysics Data System (ADS)

Carvalho, M. A.

2017-12-01

Sedimentary diagenetic processes play key role in global sulfur-iron-carbon cycle. Microbially driven organoclastic sulfate reduction and anaerobic oxidation of methane (AOM) pathways are responsible for sulfate reduction in marine sediments. Concomitant H2S production and iron sulfide precipitation lead to Fe-sulfide burial in the sediments. Intra/intermolecular organic bound sulfur is also another major sink of global sulfur burial. In the present study, we have investigated the sulfidisation process in a core from Krishna-Godavari (K-G) basin, Bay of Bengal. K-G basin is well known for gas hydrate deposits and methane enrichment within 100-120 mbsf. Previous work from K-G basin has shown tell-tale evidence of paleo episodic- methane expulsion events and formation of authigenic carbonate crust at or above the sea floor1. Our study was carried out on a core MD-161-15 (water depth of 983 m and Lat. =16° 00.5700' N;Long. = 82° 03.4502' E) recovered on board R/V Marion Dufrense). The pyrite content in the core (measured as chromium reducible sulfur: CRS) range from 0.003 to 1.1 wt%. The reactive content (FeTR = FeOx + FeD + FeCRS) range from 0.9 to 3.5 wt%, where FeOX, FeD and FeCRS represents oxalate extractable (magnetite), buffered dithionite extractable (ferrihydrite, lepidocrocite, goethite, hematite) and boiling CrCl2 (in 6N HCl) extractable (Pyrite: FeS2) iron respectively. The δ34SCRS range from -49 to +16.7 ‰ VCDT and show good positive correlation with FeTR. Presence of highly 13C depleted authigenic carbonate in the sediments within 1600-3000 mbsf indicate influence of AOM and possible methane seepage2. The δ34SCRS profile show marked 34S depletion trend within the top 1012 mbsf. Below this depth, δ34SCRS values show steadily increasing trend superimposed by zones of sharp enrichment/ depletion of 34S. The 34S enrichment trend may attributed to late diagenetic pyritization from 34S enriched H2S produced from residual pore water sulfate via AOM pathway.

Cryogenic fractionator gas as stripping gas of fines slurry in a coking and gasification process

DOEpatents

DeGeorge, Charles W.

1981-01-01

In an integrated coking and gasification process wherein a stream of fluidized solids is passed from a fluidized bed coking zone to a second fluidized bed and wherein entrained solid fines are recovered by a scrubbing process and wherein the resulting solids-liquid slurry is stripped with a stripping gas to remove acidic gases, at least a portion of the stripping gas comprises a gas comprising hydrogen, nitrogen and methane separated from the coker products.

Direct methane solid oxide fuel cells and their related applications

NASA Astrophysics Data System (ADS)

Lin, Yuanbo

Solid oxide fuel cells (SOFCs), renowned for their high electrical generation efficiency with low pollutant production, are promising for reducing global energy and environmental concerns. However, there are major barriers for SOFC commercialization. A primary challenge is reducing the capital cost of SOFC power plants to levels that can compete with other generation methods. While the focus of this thesis research was on operation of SOFCs directly with methane fuel, the underlying motivation was to make SOFCs more competitive by reducing their cost. This can be achieved by making SOFCs that reduce the size and complexity of the required "balance of plant". Firstly, direct operation of SOFCs on methane is desirable since it can eliminate the external reformer. However, effective means must be found to suppress deleterious anode coking in methane. In this thesis, the operating conditions under which SOFCs can operate stably and without anode coking were investigated in detail, and the underlying mechanisms of coking and degradation were determined. Furthermore, a novel design utilizing an inert anode barrier layer was developed and shown to substantially improve stability against coking. Secondly, the direct methane SOFCs were investigated for use as electrochemical partial oxidation (EPOx) reactors that can co-generate electricity and synthesis gas (CO+H2) from methane. The results indicated that conventional SOFCs work quite well as methane partial oxidation reactors, producing syngas at relatively high rates. While this approach would not decrease the cost of SOFC power plant, it would improve prospects for commercialization by increasing the value of the power plant, because two products, electricity and syngas, can be sold. Thirdly, SOFCs utilizing thin (La,Sr)(Ga,Mg)O3 electrolytes were demonstrated. This highly conductive material allows lower SOFC operation temperature, leading to the use of lower-cost materials for sealing, interconnection, and balance of plant. Deleterious electrolyte/electrode reactions and electrolyte La loss were avoided during high-temperature co-firing by using thin La-doped ceria barrier layers, allowing very high power densities at moderate operating temperatures. (La,Sr)(Ga,Mg)O3-(La,Sr)(Fe,Co)O3 composite cathodes were investigated and optimal processing parameters that yield low interfacial polarization resistance at intermediate temperature were determined.

Methane Decomposition and Carbon Growth on Y2O3, Yttria-Stabilized Zirconia, and ZrO2

PubMed Central

2014-01-01

Carbon deposition following thermal methane decomposition under dry and steam reforming conditions has been studied on yttria-stabilized zirconia (YSZ), Y2O3, and ZrO2 by a range of different chemical, structural, and spectroscopic characterization techniques, including aberration-corrected electron microscopy, Raman spectroscopy, electric impedance spectroscopy, and volumetric adsorption techniques. Concordantly, all experimental techniques reveal the formation of a conducting layer of disordered nanocrystalline graphite covering the individual grains of the respective pure oxides after treatment in dry methane at temperatures T ≥ 1000 K. In addition, treatment under moist methane conditions causes additional formation of carbon-nanotube-like architectures by partial detachment of the graphite layers. All experiments show that during carbon growth, no substantial reduction of any of the oxides takes place. Our results, therefore, indicate that these pure oxides can act as efficient nonmetallic substrates for methane-induced growth of different carbon species with potentially important implications regarding their use in solid oxide fuel cells. Moreover, by comparing the three oxides, we could elucidate differences in the methane reactivities of the respective SOFC-relevant purely oxidic surfaces under typical SOFC operation conditions without the presence of metallic constituents. PMID:24587591

Co-digestion of cattle manure with food waste and sludge to increase biogas production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maranon, E., E-mail: emara@uniovi.es; Castrillon, L.; Quiroga, G.

2012-10-15

Highlights: Black-Right-Pointing-Pointer Small increase in methane production was observed applying sonication pretreatment. Black-Right-Pointing-Pointer Biogas productions between 720 and 1100 mL/Lreactor day were achieved. Black-Right-Pointing-Pointer Volatile solids removal efficiencies ranged between 53% and 60%. Black-Right-Pointing-Pointer Lower methane yields were obtained when operating under thermophilic conditions. Black-Right-Pointing-Pointer Optimum OLR in lab-scale CSTR was 1.2-1.3 g VS/L day (HRT: 20 days). - Abstract: Anaerobic co-digestion strategies are needed to enhance biogas production, especially when treating certain residues such as cattle/pig manure. This paper presents a study of co-digestion of cattle manure with food waste and sewage sludge. With the aim of maximising biogasmore » yields, a series of experiments were carried out under mesophilic and thermophilic conditions using continuously stirred-tank reactors, operating at different hydraulic residence times. Pretreatment with ultrasound was also applied to compare the results with those obtained with non-pretreated waste. Specific methane production decreases when increasing the OLR and decreasing HRT. The maximum value obtained was 603 LCH{sub 4}/kg VS{sub feed} for the co-digestion of a mixture of 70% manure, 20% food waste and 10% sewage sludge (total solid concentration around 4%) at 36 Degree-Sign C, for an OLR of 1.2 g VS/L day. Increasing the OLR to 1.5 g VS/L day led to a decrease of around 20-28% in SMP. Lower methane yields were obtained when operating at 55 Degree-Sign C. The increase in methane production when applying ultrasound to the feed mixtures does not compensate for the energy spent in this pretreatment.« less

Batch co-digestion of multi-component agro-wastes.

PubMed

Misi, S N; Forster, C F

2001-10-01

In certain parts of the developing world conventional energy supplies such as electricity, gas, coal and petroleum by-products are either unavailable, too capital intensive to install, are unjustifiable due to low population densities in some semi-arid regions, or are simply unaffordable to the target population. In Zimbabwe, it has been assessed that only biomass energy can conveniently provide both lighting and space heating. Therefore, means of generating biogas from agricultural and other organic wastes, and to encourage their use is a policy which has been adopted by Zimbabwe's Department of Energy. In this study cattle slurry was mixed with a range of solid wastes and allowed to digest in 11 batch digesters. The mixtures which were used were selected on the basis of centroid design with the objective of determining whether there was either synergism or antagonism. Two trials were carried out, one based on cattle slurry, chicken manure (CM) and molasses (Mol), the other based on sheep and goat manure, chicken manure and surplus activated sludge. The criteria for judging the success of a co-digestion were volatile solids (VS) reduction, total methane production and methane yield. In the first trial, the analysis based on the methane yield showed that there was no antagonism and that the mixture of 30% cattle slurry/30% CM/40% Mol gave a synergistic effect. The analysis based on the VS destruction, however, did show that there was some very slight antagonism. In the second trial, the analysis based on the methane yield showed that there was both antagonism and synergism and that the synergism produced an extra 6.7% methane. The analysis based on the VS destruction also showed that there was both antagonism and synergism but that the effects were small.

Digester performance and microbial community changes in thermophilic and mesophilic sequencing batch reactors fed with the fine sieved fraction of municipal sewage.

PubMed

Ghasimi, Dara S M; Tao, Yu; de Kreuk, Merle; Abbas, Ben; Zandvoort, Marcel H; van Lier, Jules B

2015-12-15

This study investigates the start-up and operation of bench-scale mesophilic (35 °C) and thermophilic (55 °C) anaerobic sequencing batch reactor (SBR) digesters treating the fine sieved fraction (FSF) from raw municipal sewage. FSF was sequestered from raw municipal wastewater, in the Netherlands, using a rotating belt filter equipped with a 350 micron mesh. For the given wastewater, the major component of FSF was toilet paper, which is estimated to be 10-14 kg per year per average person in the western European countries. A seven months adaptation time was allowed for the thermophilic and mesophilic digesters in order to adapt to FSF as the sole substrate with varying dry solids content of 10-25%. Different SBR cycle durations (14, 9 and 2 days) were applied for both temperature conditions to study methane production rates, volatile fatty acids (VFAs) dynamics, lag phases, as well as changes in microbial communities. The prevailing sludge in the two digesters consisted of very different bacterial and archaeal communities, with OP9 lineage and Methanothermobacter being pre-dominant in the thermophilic digester and Bacteroides and Methanosaeta dominating the mesophilic one. Eventually, decreasing the SBR cycle period, thus increasing the FSF load, resulted in improved digester performances, particularly with regard to the thermophilic digester, i.e. shortened lag phases following the batch feedings, and reduced VFA peaks. Over time, the thermophilic digester outperformed the mesophilic one with 15% increased volatile solids (VS) destruction, irrespective to lower species diversity found at high temperature. Copyright © 2015 Elsevier Ltd. All rights reserved.

Optimisation of sewage sludge anaerobic digestion through co-digestion with OFMSW: Effect of collection system and particle size.

PubMed

Silvestre, Gracia; Bonmatí, August; Fernández, Belén

2015-09-01

The effect of organic fraction of municipal solid waste (OFMSW) loading rate and particulate size on the sewage sludge (SS) mesophilic anaerobic co-digestion was assessed in continuous stirred tank reactor at hydraulic retention time of 20days. The SS-OFMSW mixture composed by 54% of the volatile solids fed (inlet-VS), at OLR of 3.1kgCODm(-3)d(-1) (1.9kgVSm(-3)d(-1)), showed the highest increment on the volumetric methane production and yield of +200% and +59% respectively, under stable conditions. The effect of particulate size was assessed with the same mixture and same operational conditions but reducing the OFMSW particulate size from 20mm to 8mm with the aim to improve the hydrolysis step, but the results showed any influence in the OFMSW particulate size range analysed. In addition, specific biomass activity was assessed at the end of each co-digestion period. Results showed that OFMSW promoted β-oxidation syntrophic acetogens and the acetoclastic methanogens activity; although the last increase of the OFMSW percentage (from 47% to 54% inlet-VS) affected negatively the specific substrate activity, but not inhibitory effect was observed. Therefore, the results obtained in the continuous experiment could be related with some inhibitory or toxic effect and not due to hydrolysis limitation. The specific biomass activity test was demonstrated to be an interesting tool to evaluate and control the co-digestion process, especially when conventional parameters did not explain the behaviour of the biological system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Comparative Analysis of the Microbiota Between Sheep Rumen and Rabbit Cecum Provides New Insight Into Their Differential Methane Production

PubMed Central

Mi, Lan; Yang, Bin; Hu, Xialu; Luo, Yang; Liu, Jianxin; Yu, Zhongtang; Wang, Jiakun

2018-01-01

The rumen and the hindgut represent two different fermentation organs in herbivorous mammals, with the former producing much more methane than the latter. The objective of this study was to elucidate the microbial underpinning of such differential methane outputs between these two digestive organs. Methane production was measured from 5 adult sheep and 15 adult rabbits, both of which were placed in open-circuit respiratory chambers and fed the same diet (alfalfa hay). The sheep produced more methane than the rabbits per unit of metabolic body weight, digestible neutral detergent fiber, and acid detergent fiber. pH in the sheep rumen was more than 1 unit higher than that in the rabbit cecum. The acetate to propionate ratio in the rabbit cecum was more than threefold greater than that in the sheep rumen. Comparative analysis of 16S rRNA gene amplicon libraries revealed distinct microbiota between the rumen of sheep and the cecum of rabbits. Hydrogen-producing fibrolytic bacteria, especially Butyrivibrio, Succiniclastium, Mogibacterium, Prevotella, and Christensenellaceae, were more predominant in the sheep rumen, whereas non-hydrogen producing fibrolytic bacteria, such as Bacteroides, were more predominant in the rabbit cecum. The rabbit cecum had a greater predominance of acetogens, such as those in the genus Blautia, order Clostridiales, and family Ruminococcaceae. The differences in the occurrence of hydrogen-metabolizing bacteria probably explain much of the differential methane outputs from the rumen and the cecum. Future research using metatranscriptomics and metabolomics shall help confirm this premise and understand the factors that shape the differential microbiota between the two digestive organs. Furthermore, our present study strongly suggests the presence of new fibrolytic bacteria in the rabbit cecum, which may explain the stronger fibrolytic activities therein. PMID:29662480

Bioreactor Performance Parameters for an Industrially-Promising Methanotroph Methylomicrobium buryatense 5GB1

DOE PAGES

Gilman, Alexey; Laurens, Lieve M.; Puri, Aaron W.; ...

2015-11-16

Methane is a feedstock of interest for the future, both from natural gas and from renewable biogas sources. Methanotrophic bacteria have the potential to enable commercial methane bioconversion to value-added products such as fuels and chemicals. A strain of interest for such applications is Methylomicrobium buryatense 5GB1, due to its robust growth characteristics. But, to take advantage of the potential of this methanotroph, it is important to generate comprehensive bioreactor-based datasets for different growth conditions to compare bioprocess parameters. The datasets of growth parameters, gas utilization rates, and products (total biomass, extracted fatty acids, glycogen, excreted acids) were obtained formore » cultures of M. buryatense 5GB1 grown in continuous culture under methane limitation and O2 limitation conditions. Additionally, experiments were performed involving unrestricted batch growth conditions with both methane and methanol as substrate. All four growth conditions show significant differences. The most notable changes are the high glycogen content and high formate excretion for cells grown on methanol (batch), and high O2:CH4 utilization ratio for cells grown under methane limitation. The results presented here represent the most comprehensive published bioreactor datasets for a gamma-proteobacterial methanotroph. This information shows that metabolism by M. buryatense 5GB1 differs significantly for each of the four conditions tested. O2 limitation resulted in the lowest relative O2 demand and fed-batch growth on methane the highest. Future studies are needed to understand the metabolic basis of these differences. However, these results suggest that both batch and continuous culture conditions have specific advantages, depending on the product of interest.« less

Potential of tannin-rich plants, Leucaena leucocephala, Glyricidia sepium and Manihot esculenta, to reduce enteric methane emissions in sheep.

PubMed

Archimède, H; Rira, M; Barde, D J; Labirin, F; Marie-Magdeleine, C; Calif, B; Periacarpin, F; Fleury, J; Rochette, Y; Morgavi, D P; Doreau, M

2016-12-01

An in vivo trial was conducted in sheep to investigate the effect of three tropical tannin-rich plants (TRP) on methane emission, intake and digestibility. The TRP used were leaves of Glyricidia sepium, Leucaena leucocephala and Manihot esculenta that contained, respectively, 39, 75 and 92 g condensed tannins/kg DM. Methane was determined with the sulphur hexafluoride tracer technique. Eight rumen-cannulated sheep of two breeds (four Texel, four Blackbelly) were used in two 4 × 4 Latin square designs. Four experimental diets were tested. They consisted in a tropical natural grassland hay based on Dichanthium spp. fed alone (C) or in association with G. sepium (G), L. leucocephala (L) or M. esculenta (M) given as pellets at 44% of the daily ration. Daily organic matter intake was higher in TRP diets (686, 984, 1054 and 1186 g/day for C, G, L and M respectively; p < 0.05) while apparent organic matter total tract digestibility was not affected (69.9%, 62.8%, 65.3% and 64.7% for C, G, L and M respectively; p > 0.05). Methane emission was 47.1, 44.9, 33.3 and 33.5 g/kg digestible organic matter intake for C, G, L and M, respectively, and was significantly lower (p < 0.05) for L and M than for G and C. Our results confirm the potential of some TRP to reduce methane production. The strong decrease in methane and the increase in intake with TRPs may be due to their presentation as pellets. Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

First In Vivo Measurements of Methane Emissions from Ruminant Livestock Enteric Fermentation in Mexico Using Respiration Chambers

NASA Astrophysics Data System (ADS)

Castelan-Ortega, O. A.; Ku-Vera, J. C.; Molina, L. T.; Pedraza-Beltrán, P. E.; Canul-Solis, J. R.; Piñeiro-Vázquez, A.; Hernández-Pineda, G.; Benaouda, M.

2015-12-01

Until recently there were no facilities in Mexico to measure in vivo methane (CH4) emission by livestock. Inventories were calculated using emission factors from the IPCC, so the uncertainty in calculation is high. In 2014 the first laboratory equipped to measure CH4 started operations at the Universidad Autónoma de Yucatán. The second laboratory was built at the Universidad Autónoma del Estado de México and it began operations in June 2015. The first laboratory consists of two open-circuit respiration chambers, which are currently used to measure CH4 emissions by cattle in Mexico's tropical regions. Chamber dimensions are: 3.0 x 2.14 x 1.44 m (DxHxW). Air exiting the chambers is drawn by a mass flowmeter (Flowkit 500) at a rate of 500 L/min. The air sample is passed through a multiplexer and then through a chemical desiccant before entering the methane infrared analyzer (MA-10). All the instruments were fabricated by Sable Systems International, Las Vegas, USA. The average CH4 emission factor for Nelore bulls of 350 kg live weight fed with a tropical grass was 117.3 L/day and it increased to 198.6 L/day when 3 kg of concentrate feed were supplemented. For adult crossbred cows also fed with a tropical grass CH4 emission ranged from 92.7 to 137.3 L/day. The second laboratory consist of a respiration chamber of the head box type. It consists of a head box of 1.05 x 0.8 x 1.80 m (WxDxH) made of 3.5 x 3.5 cm stainless steel angle, and on the bottom, top, sides, back and front of the head box, 0.6 cm clear acrylic sheeting was used to provide comfortable vision to the animal, and a metabolic cage of 1.08 x 2.92 x 1.8 m (WxDxH) made of iron tubes with steel sheeting floor adapted for feces and urine collection. The methane analyzer and the mass flowmeter were of the same model as in the first laboratory. Once calibrated, in vivo measurements were performed using high yielding adult Holstein cows with an average live weight of 573 ±71 kg and milk yield of 30kg/day. The cows were fed maize silage, alfalfa hay and 4 kg concentrate feed. The average CH4 production was 484 ± 132 L/day. Emission factors obtained from both laboratories differed substantially from those used previously for inventories calculation in Mexico. IPCC factors are higher than those observed in our work particularly for cattle in the tropical regions of the country.

LMOP Special Session

EPA Pesticide Factsheets

The Landfill Methane Outreach Program (LMOP) is collaborating with the Solid Waste Association of North America (SWANA) to organize a panel in conjunction with their upcoming 41st Annual Landfill Gas and Biogas Symposium in Denver, Colorado.

Nuclear spin relaxation of methane in solid xenon

NASA Astrophysics Data System (ADS)

Sugimoto, Takeru; Arakawa, Ichiro; Yamakawa, Koichiro

2018-03-01

Nuclear spin relaxation of methane in solid xenon has been studied by infrared spectroscopy. From the analysis of the temporal changes of the rovibrational peaks, the rates of the nuclear spin relaxation of I = 2 ← 1 correlated to the rotational relaxation of J = 0 ← 1 were obtained at temperatures of 5.1-11.5 K. On the basis of the temperature dependence of the relaxation rate, the activation energy of the indirect two-phonon process was determined to be 50 ± 6 K, which is in good agreement with the rotational transition energies of J = 2 ← 1 and J = 3 ← 1. Taking into account this result and the spin degeneracy, we argue that the lowest J = 3 level in which the I = 1 and I = 2 states are degenerate acts as the intermediate point of the indirect process.

Use of solid residue from thermal power plant (fly ash) for enhancing sewage sludge anaerobic digestion: Influence of fly ash particle size.

PubMed

Montalvo, S; Cahn, I; Borja, R; Huiliñir, C; Guerrero, L

2017-11-01

The influence of fly ash particle size on methane production and anaerobic biodegradability was evaluated. Assays with different fly ash particle sizes (0.8-2.36mm) at a concentration of 50mg/L were ran under mesophilic conditions. In anaerobic processes operating with fly ash, greater removal of both volatile total and suspended solids, chemical oxygen demand (total and soluble) was achieved, with an increase of methane production between 28% and 96% compared to the control reactors. The highest increase occurred at ash particles sizes of 1.0-1.4mm. The metal concentrations in the digestates obtained after anaerobic digestion of sewage sludge are far below those considered as limiting for the use of sludge in soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of feeding dry or modified wet distillers grains with solubles with or without supplemental calcium oxide on ruminal metabolism and microbial enzymatic activity of beef cattle.

PubMed

Schroeder, A R; Iakiviak, M; Felix, T L

2014-09-01

The objectives of this study were to determine the interaction of feeding dry (DDGS) or modified wet (MDGS) distillers grains with solubles (DGS) with or without supplemental CaO on in situ DM and NDF disappearance; ruminal pH, VFA, and methane concentration; and cellulase and xylanase activity. Fistulated steers (n = 8; average initial BW = 540 ± 250 kg) were used in a replicated 4 × 4 Latin square design. Treatments were arranged in a 2 × 2 factorial, and steers were randomly allotted to 1 of 4 dietary treatments: 1) 50% DDGS with 0% CaO, 2) 48.8% DDGS supplemented with 1.2% CaO, 3) 50% MDGS with 0% CaO, or 4) 48.8% MDGS supplemented with 1.2% CaO (DM basis). The remainder of the diet was husklage, dry-rolled corn, and vitamin and mineral supplement. There were no interactions (P ≥ 0.12) of DGS type and CaO addition on any parameters measured. Steers fed DDGS had a 17% increase (P < 0.01) in DMI compared to steers fed MDGS; however, CaO supplementation reduced (P = 0.03) DMI by 12%, regardless of DGS type. As expected, addition of CaO increased the pH of the diet by 1.82 pH units. This caused a time by CaO interaction (P = 0.05) for ruminal pH. Regardless of DGS type, steers supplemented with CaO tended to have increased (P = 0.09) ruminal pH at 1.5 h and had increased (P = 0.03) ruminal pH at 3 h postfeeding; however, ruminal pH did not differ (P ≥ 0.24) for the remainder of the day. There was no difference (P = 0.46) in ruminal cellulase activity when comparing type of DGS fed. However, there was a time by CaO interaction (P < 0.01); cattle fed 1.2% CaO diets had 28% greater ruminal cellulase activity only at 0 h postfeeding when compared to cattle fed 0% CaO. Furthermore, feeding supplemental CaO increased (P = 0.04) acetate to propionate ratio (A:P) regardless of type of DGS fed. Increased initial ruminal pH and cellulase activity from supplemental CaO did not increase (P = 0.48) in situ NDF disappearance. No differences (P ≥ 0.48) in ruminal methane concentration were found when comparing DGS type or supplemental CaO. In conclusion, the type of DGS fed had little effect on ruminal metabolism. Even though CaO increased ruminal pH and cellulase activity at some times postfeeding, it was not enough to affect in situ fiber disappearance.

Co-digestion of dairy cattle slurry and industrial meat-processing by-products--effect of ultrasound and hygienization pre-treatments.

PubMed

Luste, Sami; Heinonen-Tanski, Helvi; Luostarinen, Sari

2012-01-01

Anaerobic co-digestion of a mixture of industrial animal by-products (ABP) from meat-processing in conjunction with dairy cattle slurry (mixed in a ratio of 1:3; w.w.) was evaluated at 35 °C focusing on methane production and stabilization. Three pre-treatments were applied (1) digestion with no pre-treatment (control), (2) ultrasound, and (3) thermal hygienization (70 °C, 60 min). Methane production potentials (MPP) of the untreated, ultrasound pre-treated and hygienized feed mixtures were 300, 340, and 360 m(3) CH(4)/t volatile solids (VS) added, as determined in the batch experiments. However, the specific methane productions (SMP) achieved in reactor experiments (hydraulic retention time HRT 21 d, organic loading rate OLR 3.0±0.1 kg VS/m(3) d) were 11±2% (untreated and ultrasound pre-treated) and 22±3% (hygienized) lower than the potentials. Ultrasound with the energy input of 1000 kJ/kg total solids (TS) and hygienization of the ready-made feed were the most suitable pre-treatment modes studied. Copyright © 2011 Elsevier Ltd. All rights reserved.

Life cycle assessment of four municipal solid waste management scenarios in China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong Jinglan, E-mail: hongjing@sdu.edu.c; Li Xiangzhi; Zhaojie Cui

2010-11-15

A life cycle assessment was carried out to estimate the environmental impact of municipal solid waste. Four scenarios mostly used in China were compared to assess the influence of various technologies on environment: (1) landfill, (2) incineration, (3) composting plus landfill, and (4) composting plus incineration. In all scenarios, the technologies significantly contribute to global warming and increase the adverse impact of non-carcinogens on the environment. The technologies played only a small role in the impact of carcinogens, respiratory inorganics, terrestrial ecotoxicity, and non-renewable energy. Similarly, the influence of the technologies on the way other elements affect the environment wasmore » ignorable. Specifically, the direct emissions from the operation processes involved played an important role in most scenarios except for incineration, while potential impact generated from transport, infrastructure and energy consumption were quite small. In addition, in the global warming category, highest potential impact was observed in landfill because of the direct methane gas emissions. Electricity recovery from methane gas was the key factor for reducing the potential impact of global warming. Therefore, increasing the use of methane gas to recover electricity is highly recommended to reduce the adverse impact of landfills on the environment.« less

Anaerobic co-digestion of livestock and vegetable processing wastes: fibre degradation and digestate stability.

PubMed

Molinuevo-Salces, Beatriz; Gómez, Xiomar; Morán, Antonio; García-González, Mari Cruz

2013-06-01

Anaerobic digestion of livestock wastes (swine manure (SM) and poultry litter (PL)) and vegetable processing wastes (VPW) mixtures was evaluated in terms of methane yield, volatile solids removal and lignocellulosic material degradation. Batch experiments were performed with 2% VS (volatile solids) to ensure complete conversion of TVFAs (total volatile fatty acids) and to avoid ammonia inhibition. Experimental methane yields obtained for the mixtures resulted in higher values than those obtained from the sum of the methane yields from the individual components. VPW addition to livestock wastes before anaerobic digestion also resulted in improved VS elimination. In SM-VPW co-digestions, CH4 yield increased from 111 to 244 mL CH4 g VS added(-1), and the percentage of VS removed increased from 50% to 86%. For PL-VPW co-digestions, the corresponding values were increased from 158 to 223 mL CH4 g VS added(-1) and from 70% to 92% VS removed. Hemicelluloses and more than 50% of cellulose were degraded during anaerobic digestion. Thermal analyses indicated that the stabilization of the wastes during anaerobic digestion resulted in significantly less energy being released by digestate samples than fresh samples. Copyright © 2013 Elsevier Ltd. All rights reserved.

Starch source evaluation in calf starter: I. Feed consumption, body weight gain, structural growth, and blood metabolites in Holstein calves.

PubMed

Khan, M A; Lee, H J; Lee, W S; Kim, H S; Kim, S B; Ki, K S; Park, S J; Ha, J K; Choi, Y J

2007-11-01

Holstein calves were fed pelleted iso-starch (25% of starter dry matter) diets containing barley (n = 16), corn (n = 16), oat (n = 16), and wheat (n = 16) starch for 12 wk of age. Feed consumption, nutrient intake, body weight (BW) gain, skeletal growth, and selected blood metabolites in calves during preweaning (d 1 to 49) and postweaning (d 50 to 84) periods were measured. Average daily starter consumption during pre-weaning and postweaning periods was the greatest in calves fed corn died followed by those fed a wheat diet and then in those fed barley and oat diets. During the preweaning period, the calves provided corn and wheat diets consumed greater amount of mixed grass hay than those fed barley and oat diets. During the postweaning period, mixed grass hay intake was the greatest in calves provided corn diet followed by those fed a wheat diet and then in those fed barley and oat diets. Nutrients (dry matter, crude protein, starch, and neutral detergent fiber) intake followed the solid feed consumption pattern in calves. Body weight and body measurements (body length, body barrel, heart girth, wither height, and hip height) at birth and at weaning (d 49) in calves fed different starch sources were similar. Body weight and body measurements at postweaning (d 84) were the greatest in calves fed a corn diet followed by those fed a wheat diet and then in those fed barley and oat diets. Overall average BW gain and total dry matter intake were the greatest in calves fed a corn diet than in those fed wheat, barley, and oat diets. Feed efficiency was greater in calves fed corn and wheat diets than in those fed barley and oat diets. Blood glucose, blood urea N, triglycerides, cholesterol, and creatinine were reduced with the advancing age of calves. Lesser blood glucose and greater blood urea N concentrations at wk 8, 10, and 12 of age were noticed in calves fed corn diet than in those fed barley, oat, and wheat diets. Occurrence of diarrhea was more frequent in calves fed oat diet than in those provided barley, corn, and wheat diets. Starch sources did not influence respiratory score, rectal temperature, and general appearance score. In conclusion, the calves on corn diet consumed more solid feed and gained greater BW than those fed barley, oat, and wheat diets.

Supercritical/Solid Catalyst (SSC)

ScienceCinema

Ginosar, Daniel; Fox, Robert; Bright, Patricia

2018-05-23

INL's patented, continuous-flow Supercritical/Solid Catalyst (SSC) produces the highest ASTM-quality B-100 biodiesel from waste fats, oils, and greases at the site of waste generation. SSC delivers low-cost transportation fuel, avoids significant landfill costs for municipalities, and reduces potent methane and other emissions produced in landfills from these wastes. You can learn more about INL's energy research programs at http://www.facebook.com/idahonationallaboratory.

Supercritical/Solid Catalyst (SSC)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ginosar, Daniel; Fox, Robert; Bright, Patricia

2010-05-28

INL's patented, continuous-flow Supercritical/Solid Catalyst (SSC) produces the highest ASTM-quality B-100 biodiesel from waste fats, oils, and greases at the site of waste generation. SSC delivers low-cost transportation fuel, avoids significant landfill costs for municipalities, and reduces potent methane and other emissions produced in landfills from these wastes. You can learn more about INL's energy research programs at http://www.facebook.com/idahonationallaboratory.

A Multifaceted Study of Methane Adsorption in Metal-Organic Frameworks by Using Three Complementary Techniques.

PubMed

Zhang, Yue; Lucier, Bryan E G; Fischer, Michael; Gan, Zhehong; Boyle, Paul D; Desveaux, Bligh; Huang, Yining

2018-03-25

Methane is a promising clean and inexpensive energy alternative to traditional fossil fuels, however, its low volumetric energy density at ambient conditions has made devising viable, efficient methane storage systems very challenging. Metal-organic frameworks (MOFs) are promising candidates for methane storage. In order to improve the methane storage capacity of MOFs, a better understanding of the methane adsorption, mobility, and host-guest interactions within MOFs must be realized. In this study, methane adsorption within α-Mg 3 (HCO 2 ) 6 , α-Zn 3 (HCO 2 ) 6 , SIFSIX-3-Zn, and M-MOF-74 (M=Mg, Zn, Ni, Co) has been comprehensively examined. Single-crystal X-ray diffraction (SCXRD) experiments and DFT calculations of the methane adsorption locations were performed for α-Mg 3 (HCO 2 ) 6 , α-Zn 3 (HCO 2 ) 6 , and SIFSIX-3-Zn. The SCXRD thermal ellipsoids indicate that methane possesses significant mobility at the adsorption sites in each system. 2 H solid-state NMR (SSNMR) experiments targeting deuterated CH 3 D guests in α-Mg 3 (HCO 2 ) 6 , α-Zn 3 (HCO 2 ) 6 , SIFSIX-3-Zn, and MOF-74 yield an interesting finding: the 2 H SSNMR spectra of methane adsorbed in these MOFs are significantly influenced by the chemical shielding anisotropy in addition to the quadrupolar interaction. The chemical shielding anisotropy contribution is likely due mainly to the nuclear independent chemical shift effect on the MOF surfaces. In addition, the 2 H SSNMR results and DFT calculations strongly indicate that the methane adsorption strength is linked to the MOF pore size and that dispersive forces are responsible for the methane adsorption in these systems. This work lays a very promising foundation for future studies of methane adsorption locations and dynamics within adsorbent MOF materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal properties of methane gas hydrates

USGS Publications Warehouse

Waite, William F.

2007-01-01

Gas hydrates are crystalline solids in which molecules of a “guest” species occupy and stabilize cages formed by water molecules. Similar to ice in appearance (fig. 1), gas hydrates are stable at high pressures and temperatures above freezing (0°C). Methane is the most common naturally occurring hydrate guest species. Methane hydrates, also called simply “gas hydrates,” are extremely concentrated stores of methane and are found in shallow permafrost and continental margin sediments worldwide. Brought to sea-level conditions, methane hydrate breaks down and releases up to 160 times its own volume in methane gas. The methane stored in gas hydrates is of interest and concern to policy makers as a potential alternative energy resource and as a potent greenhouse gas that could be released from sediments to the atmosphere and ocean during global warming. In continental margin settings, methane release from gas hydrates also is a potential geohazard and could cause submarine landslides that endanger offshore infrastructure. Gas hydrate stability is sensitive to temperature changes. To understand methane release from gas hydrate, the U.S. Geological Survey (USGS) conducted a laboratory investigation of pure methane hydrate thermal properties at conditions relevant to accumulations of naturally occurring methane hydrate. Prior to this work, thermal properties for gas hydrates generally were measured on analog systems such as ice and non-methane hydrates or at temperatures below freezing; these conditions limit direct comparisons to methane hydrates in marine and permafrost sediment. Three thermal properties, defined succinctly by Briaud and Chaouch (1997), are estimated from the experiments described here: - Thermal conductivity, λ: if λ is high, heat travels easily through the material. - Thermal diffusivity, κ: if κ is high, it takes little time for the temperature to rise in the material. - Specific heat, cp: if cp is high, it takes a great deal of heat to raise the temperature of the material.

Biogasification of Walt Disney World biomass waste blend. Annual report, January-December 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biljetina, R.; Chynoweth, D.P.; Janulis, J.

1984-09-01

The objective of this research is to develop efficient processes for conversion of biomass-waste blends to methane and other resources. To evaluate the technical and economic feasibility, an experimental test unit (ETU) was designed and installed at the Reedy Creek Wastewater Treatment Plant at Walt Disney World in Lake Buena Vista, Florida. The facility integrates a biomethanogenic conversion process with a wastewater treatment process employing water hyacinth ponds for secondary and tertiary treatment of sewage. Harvested water hyacinth is subsequently combined with sludge from the primary wastewater clarifier and fed at 1-wet-ton per day to the ETU digester. This resultsmore » in the production of methane and other useful byproducts. Design, procurement of equipment, and installation has been completed. Start-up of the ETU is in progress.« less

Effects of co-digestion of cucumber residues to corn stover and pig manure ratio on methane production in solid state anaerobic digestion.

PubMed

Wang, Yaya; Li, Guoxue; Chi, Menghao; Sun, Yanbo; Zhang, Jiaxing; Jiang, Shixu; Cui, Zongjun

2018-02-01

This study investigated the performance of co-digesting cucumber residues, corn stover, and pig manure at different ratios. Microbial community structure was analyzed to elucidate functional microorganism contributing to methane production during co-digestion. Results show that mixing cucumber residues with pig manure and corn stover could significantly improved methane yields 1.27-3.46 times higher than mono-feedstock. The methane yields decreased with the cucumber residues increasing when the pig manure ratio was fixed at 4 and 3, and was opposite at ratio 5. The optimal mixture ratio was T2 with the highest methane yield (305.4 mL/g VS) and co-digestion performance index (1.97). The main microbiological community in T2 was bacteria of Firmicutes (44.6%), Bacteroidetes (32.5%), Synergistetes (3.8%) and archaea of Methanosaeta (37.1%), Methanospirillum (18.2%). The mixture ratios changed the microbial community structures. The adding proportion of cucumber residues changed the community composition of the archaea, especially the proportion of Methanosaeta. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimization of methane production by combining organic waste and cow manure as feedstock in anaerobic digestion

NASA Astrophysics Data System (ADS)

Theresia, Martha; Priadi, Cindy Rianti

2017-03-01

The anaerobic digestion (AD) process from organic waste is often unstable due to the high concentration of Volatile Fatty Acids (VFAs). The purpose of this research was to determine/evaluate the production of methane using biochemical methane potential (BMP) test with two substrate combinations, consisted of organic waste and cow manure as buffer. BMP test conducted for 35 days at a temperature of ± 35°C by measuring the volume and concentration of biogas every week and testing the sample characteristics before and after the test. The result of the sample variation showed there was no significantly difference of methane volume in the 5th week except the variation of organic waste/cow manure: 12/1 to 3/1, but the sample with a ratio of 3/1 yielded the highest methane potential of 0,58 ± 0.015 (n = 3) LCH4/gr Volatile Solid. The addition of cow manure stabilized the condition of all variations during BMP test with VFAs/alkalinity <0.3 although Carbon/Nitogen ratio of each variation is <20.

Formulation of steam-methane reforming rate in Ni-YSZ porous anode of solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Sugihara, Shinichi; Kawamura, Yusuke; Iwai, Hiroshi

2018-02-01

The steam-methane reforming reaction on a Ni-YSZ (yttria-stabilized zirconia) cermet was experimentally investigated under atmospheric pressure and in the temperature range from 650 to 750 °C. We examined the effects of the partial pressures of methane and steam in the supply gas on the reaction rate. The experiments were conducted with a low Ni contained Ni-YSZ cermet sheet of thickness 0.1 mm. Its porous microstructure and accompanied parameters were quantified using the FIB-SEM (focused ion beam scanning electron microscopy) technique. A power-law-type rate equation incorporating the reaction-rate-limiting conditions was obtained on the basis of the unit surface area of the Ni-pore contact surface in the cermet. The kinetics indicated a strong positive dependence on the methane partial pressure and a negative dependence on the steam partial pressure. The obtained rate equation successfully reproduced the experimental results for Ni-YSZ samples having different microstructures in the case of low methane consumption. The equation also reproduced the limiting-reaction behaviours at different temperatures.

Enhancement of methane production from co-digestion of chicken manure with agricultural wastes.

PubMed

Abouelenien, Fatma; Namba, Yuzaburo; Kosseva, Maria R; Nishio, Naomichi; Nakashimada, Yutaka

2014-05-01

The potential for methane production from semi-solid chicken manure (CM) and mixture of agricultural wastes (AWS) in a co-digestion process has been experimentally evaluated at thermophilic and mesophilic temperatures. To the best of author(')s knowledge, it is the first time that CM is co-digested with mixture of AWS consisting of coconut waste, cassava waste, and coffee grounds. Two types of anaerobic digestion processes (AD process) were used, process 1 (P1) using fresh CM (FCM) and process 2 (P2) using treated CM (TCM), ammonia stripped CM, were conducted. Methane production in P1 was increased by 93% and 50% compared to control (no AWS added) with maximum methane production of 502 and 506 mL g(-1)VS obtained at 55°C and 35°C, respectively. Additionally, 42% increase in methane production was observed with maximum volume of 695 mL g(-1)VS comparing P2 test with P2 control under 55°C. Ammonia accumulation was reduced by 39% and 32% in P1 and P2 tests. Copyright © 2014 Elsevier Ltd. All rights reserved.

Anaerobic co-digestion of steam-treated Quercus serrata chips and sewage sludge under mesophilic and thermophilic conditions.

PubMed

Wang, Feng; Hidaka, Taira; Sakurai, Kensuke; Tsumori, Jun

2014-08-01

The biodegradation of Quercus serrata chips was evaluated by anaerobic digestion under various steam explosion conditions. In continuous experiments, untreated chips (W₀) and chips steam-treated at less than 1.0 MPa (W₁) and 2.0 MPa (W₄) were co-digested with sewage sludge (S₁ and S₂) taken from two different wastewater treatment plants. The apparent methane yield of W₁ and W₄ co-digested with S₁ (thermophilic) was 261 dm(3)/kgVS (volatile solids) and 248 dm(3)/kgVS, respectively. The apparent methane yield of W₄ co-digested with S₂ was 258 dm(3)/kgVS (mesophilic) and 271 dm(3)/kgVS (thermophilic). Methane production was inhibited by W₀ due to components released during hydrolysis. The methane conversion ratio of pretreated chips obtained in batch experiments varied from 40.5% to 53.8% (mesophilic) and from 49.0% to 63.7% (thermophilic). The methane conversion ratio increased with decreasing acid-soluble lignin content in the chips. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhanced methane production from Taihu Lake blue algae by anaerobic co-digestion with corn straw in continuous feed digesters.

PubMed

Zhong, Weizhang; Chi, Lina; Luo, Yijing; Zhang, Zhongzhi; Zhang, Zhenjia; Wu, Wei-Min

2013-04-01

Anaerobic digestion of Taihu blue algae was tested in laboratory scale, continuous feed digesters (hydraulic retention time 10 days) at 35°C and various organic loading rates (OLR). The methane production and biomass digestion performed well at OLR below 4.00 gVSL(-1)d(-1) but deteriorated as OLR increased due to the increased ammonia concentration, causing inhibition mainly to acetate and propionate degradation. Supplementing corn straw as co-feedstock significantly improved the digestion performance. The optimal C/N ratio for the co-digestion was 20:1 at OLR of 6.00 gVSL(-1) d(-1). Methane yield of 234 mL CH4 gVS(-1) and methane productivity of 1404 mL CH4 L(-1) d(-1) were achieved with solid removal of 63%. Compared with the algae alone, the methane productivity was increased by 46% with less accumulation of ammonia and fatty acids. The reactor rate-limiting step was acetate and propionate degradation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Mixed fuel strategy for carbon deposition mitigation in solid oxide fuel cells at intermediate temperatures.

PubMed

Su, Chao; Chen, Yubo; Wang, Wei; Ran, Ran; Shao, Zongping; Diniz da Costa, João C; Liu, Shaomin

2014-06-17

In this study, we propose and experimentally verified that methane and formic acid mixed fuel can be employed to sustain solid oxide fuel cells (SOFCs) to deliver high power outputs at intermediate temperatures and simultaneously reduce the coke formation over the anode catalyst. In this SOFC system, methane itself was one part of the fuel, but it also played as the carrier gas to deliver the formic acid to reach the anode chamber. On the other hand, the products from the thermal decomposition of formic acid helped to reduce the carbon deposition from methane cracking. In order to clarify the reaction pathways for carbon formation and elimination occurring in the anode chamber during the SOFC operation, O2-TPO and SEM analysis were carried out together with the theoretical calculation. Electrochemical tests demonstrated that stable and high power output at an intermediate temperature range was well-maintained with a peak power density of 1061 mW cm(-2) at 750 °C. With the synergic functions provided by the mixed fuel, the SOFC was running for 3 days without any sign of cell performance decay. In sharp contrast, fuelled by pure methane and tested at similar conditions, the SOFC immediately failed after running for only 30 min due to significant carbon deposition. This work opens a new way for SOFC to conquer the annoying problem of carbon deposition just by properly selecting the fuel components to realize their synergic effects.

The combined effects of supplementing monensin and 3-nitrooxypropanol on methane emissions, growth rate, and feed conversion efficiency in beef cattle fed high forage and high grain diets.

PubMed

Vyas, Diwakar; Alemu, Aklilu W; McGinn, Sean M; Duval, Stephane M; Kindermann, Maik; Beauchemin, Karen A

2018-05-05

The study objective was to evaluate the combined effects of supplementing monensin (MON) and the methane (CH4) inhibitor 3-nitrooxypropanol (NOP) on enteric CH4 emissions, growth rate and feed conversion efficiency of backgrounding and finishing beef cattle. Two hundred and forty crossbred steers were used in a 238-d feeding study and fed a backgrounding diet for the first 105-d (backgrounding phase), transition diets for 28 d, followed by a finishing diet for 105-d (finishing phase). Treatments were: 1) Control (no additive); 2) MON (monensin supplemented at 33 mg/kg DM; 3) NOP (3-nitrooxypropanol supplemented at 200 mg/kg DM for backgrounding or 125 mg/kg DM for finishing phase); 4) MONOP (33 mg/kg DM MON supplemented with either 200 mg/kg DM or 125 mg/kg DM NOP). The experiment was a randomized complete block (weight: heavy and light) design with 2 (NOP) × 2 (MON) factorial arrangement of treatments using 24 pens (8 cattle/pen; 6 pens/treatment) at the main feedlot and 8 pens (6 cattle/pen; 2 pens/treatment) at the controlled environment building (CEB) feedlot. Five animals per treatment were moved to chambers for methane measurements during both phases. Data were analyzed using a Mixed procedure of SAS with pen as experimental unit (except CH4). Location (Main vs CEB) had no significant effect and was thus omitted from the final model. Overall, there were few interactions between MON and NOP indicating that the effects of the 2 compounds were independent. When cattle were fed the backgrounding diet, pen DMI was decreased by 7% while gain-to-feed ratio (G:F) was improved by 5% with NOP supplementation (P < 0.01). Similarly, MON improved G:F ratio by 4% (P < 0.01), but without affecting DMI. During the finishing phase, DMI tended (P = 0.06) to decrease by 5% with both MON (5%) and NOP (5%), while average daily gain tended (P = 0.08) to decrease by 3% with MON. Gain-to-feed ratio for finishing cattle was improved with NOP by 3% (P < 0.01); however, no effects were observed with MON. 3-Nitrooxypropanol decreased CH4 yield (g/kg DMI) by 42% and 37% with backgrounding and finishing diets (P ≤ 0.01), respectively, while MON did not lower CH4 yield. Overall, these results demonstrate efficacy of NOP in reducing enteric CH4 emissions and subsequently improving feed conversion efficiency in cattle fed high forage and high grain diets. Furthermore, effects of NOP did not depend upon whether MON was included in the diet.

Methane production in ruminants: Its effect on the doubly labeled water method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Midwood, A.J.; Haggarty, P.; McGaw, B.A.

1989-12-01

The doubly labeled water (DLW) technique for measuring CO2 production (rCO2) in free-living animals requires an assessment of the elimination of both 2H and 18O from the body over a long period of time. To calculate rCO2, it is necessary to calculate water turnover (rH2O) from the 2H flux rate. In ruminant animals, the accuracy of this calculation is affected by the loss of 2H in methane. We have quantified the effect of methane production (rCH4) on the 2H flux rate, determined in four sheep given 2H2O. The methane produced was depleted in 2H relative to the urine. A relationshipmore » between the enrichment of the methane and urine was established. The ratio of urine to methane enrichment was found on average to be 0.6536, and this value was unaffected by the level of rCH4 but showed some dependence on the absolute concentration of 2H in urine. For this reason, the ratio value obtained from four sheep not given 2H2O was different, a mean of 0.6886 was measured, this ratio was unaffected by changes in the diet supplied to the animals. Computer modeling was used to illustrate the dependence of the isotopically derived value for rCO2 on not only rCH4 but also the magnitude of rCO2 itself. The effect of rCH4 on the DLW method can be predicted from the observed ratio of rCO2 to rCH4 and the value of 0.6536 obtained for the ratio of methane to urine enrichment. With the use of data from several studies at this Institute, a limited range of 10 to 20 was found for rCO2/rCH4 in animals fed at or above maintenance.« less

Mitigation of methane emissions in a pilot-scale biocover system at the AV Miljø Landfill, Denmark: 1. System design and gas distribution.

PubMed

Cassini, Filippo; Scheutz, Charlotte; Skov, Bent H; Mou, Zishen; Kjeldsen, Peter

2017-05-01

Greenhouse gas mitigation at landfills by methane oxidation in engineered biocover systems is believed to be a cost effective technology, but so far a full quantitative evaluation of the efficiency of the technology in full scale has only been carried out in a few cases. A third generation semi-passive biocover system was constructed at the AV Miljø Landfill, Denmark. The biocover system was fed by landfill gas pumped out of three leachate collection wells. An innovative gas distribution system was used to overcome the commonly observed surface emission hot spot areas resulting from an uneven gas distribution to the active methane oxidation layer, leading to areas with methane overloading. Performed screening of methane and carbon dioxide surface concentrations, as well as flux measurement using a flux chamber at the surface of the biocover, showed homogenous distributions indicating an even gas distribution. This was supported by results from a tracer gas test where the compound HFC-134a was added to the gas inlet over an adequately long time period to obtain tracer gas stationarity in the whole biocover system. Studies of the tracer gas movement within the biocover system showed a very even gas distribution in gas probes installed in the gas distribution layer. Also the flux of tracer gas out of the biocover surface, as measured by flux chamber technique, showed a spatially even distribution. Installed probes logging the temperature and moisture content of the methane oxidation layer at different depths showed elevated temperatures in the layer with temperature differences to the ambient temperature in the range of 25-50°C at the deepest measuring point due to the microbial processes occurring in the layer. The moisture measurements showed that infiltrating precipitation was efficiently drained away from the methane oxidation layer. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modeling, simulation and optimization of a no-chamber solid oxide fuel cell operated with a flat-flame burner

NASA Astrophysics Data System (ADS)

Vogler, Marcel; Horiuchi, Michio; Bessler, Wolfgang G.

A detailed computational model of a direct-flame solid oxide fuel cell (DFFC) is presented. The DFFC is based on a fuel-rich methane-air flame stabilized on a flat-flame burner and coupled to a solid oxide fuel cell (SOFC). The model consists of an elementary kinetic description of the premixed methane-air flame, a stagnation-point flow description of the coupled heat and mass transport within the gas phase, an elementary kinetic description of the electrochemistry, as well as heat, mass and charge transport within the SOFC. Simulated current-voltage characteristics show excellent agreement with experimental data published earlier (Kronemayer et al., 2007 [10]). The model-based analysis of loss processes reveals that ohmic resistance in the current collection wires dominates polarization losses, while electronic loss currents in the mixed conducting electrolyte have only little influence on the polarized cell. The model was used to propose an optimized cell design. Based on this analysis, power densities of above 200 mW cm -2 can be expected.

Anaerobic digestion of municipal solid waste composed of food waste, wastepaper, and plastic in a single-stage system: performance and microbial community structure characterization.

PubMed

Wan, Shungang; Sun, Lei; Douieb, Yaniv; Sun, Jian; Luo, Wensui

2013-10-01

The performance of municipal organic solid waste anaerobic digestion was investigated using a single-stage bioreactor, and the microbial community structures were characterized during the digestion. The results showed that the biogas and methane production rates were 592.4 and 370.1L/kg with volatile solid added at the ratio of 2:1:1 for food waste, wastepaper, and plastic based on dry weight. The methane volume concentration fluctuated between 44.3% and 75.4% at steady stage. Acetic acid, propionic acid, and butyric acid were the major volatile fatty acids produced during the digestion process. The anaerobic process was not inhibited by the accumulation of ammonia and free ammonia. The bacterial community was found to consist of at least 21 bands of bacteria and 12 bands of archaea at the steady state. All of the results indicated that the mixture of food waste, wastepaper, and plastic could be efficiently co-digested using the anaerobic digestion system. Copyright © 2013 Elsevier Ltd. All rights reserved.

Scaling methane oxidation: From laboratory incubation experiments to landfill cover field conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abichou, Tarek, E-mail: abichou@eng.fsu.edu; Mahieu, Koenraad; Chanton, Jeff

2011-05-15

Evaluating field-scale methane oxidation in landfill cover soils using numerical models is gaining interest in the solid waste industry as research has made it clear that methane oxidation in the field is a complex function of climatic conditions, soil type, cover design, and incoming flux of landfill gas from the waste mass. Numerical models can account for these parameters as they change with time and space under field conditions. In this study, we developed temperature, and water content correction factors for methane oxidation parameters. We also introduced a possible correction to account for the different soil structure under field conditions.more » These parameters were defined in laboratory incubation experiments performed on homogenized soil specimens and were used to predict the actual methane oxidation rates to be expected under field conditions. Water content and temperature corrections factors were obtained for the methane oxidation rate parameter to be used when modeling methane oxidation in the field. To predict in situ measured rates of methane with the model it was necessary to set the half saturation constant of methane and oxygen, K{sub m}, to 5%, approximately five times larger than laboratory measured values. We hypothesize that this discrepancy reflects differences in soil structure between homogenized soil conditions in the lab and actual aggregated soil structure in the field. When all of these correction factors were re-introduced into the oxidation module of our model, it was able to reproduce surface emissions (as measured by static flux chambers) and percent oxidation (as measured by stable isotope techniques) within the range measured in the field.« less

Field test of methane fermentation system for treating swine wastes.

PubMed

Kataoka, N; Suzuki, T; Ishida, K; Yamada, N; Kurata, N; Katayose, M; Honda, K

2002-01-01

A methane fermentation system for treating swine wastes was developed and successfully demonstrated in a field test plant (0.5 m3/d). The system was composed of a screw-press dehydrator, a methanogenic digester, a sludge separator, an oxidation ditch (OD) and composting equipment. A performance evaluation was carried out regarding physical pre-treatment using the screw-press dehydrator, methane fermentation for pre-treated slurry, and post-treatment for digested effluent by OD. Total solids (TS) and chemical oxygen demand (CODCr) removal by the screw-press pre-treatment were 38% and 22%, respectively. Properties of the screenings were as follows: water content 57%, ignition loss 93%, specific gravity 0.33. The pretreated strong slurry was digested under mesophilic conditions. Digestion gas (biogas) production rate was 25 m3/m3-slurry (NTP) and methane content of the biogas was 67%. CODCr removal of 65% with methane fermentation treatment of the slurry operating at 35 degrees C was observed. No inhibition of methane fermentation reaction occurred at the NH4(+)-N concentration of 3,000 mg/l or less during methane fermentation by the system. Mass balance from the present pilot-scale study showed that 1 m3 of mixture of excrement and urine of swine waste (TS 90 kg/m3) was biologically converted to 25 m3/m3-slurry (NTP) of biogas (methane content 67%), 100 kg of compost (water content 40%, ignition loss 75%), and 0.80 m3 of treated water (SS 30-70 mg/l).

Community Composition and Ultrastructure of a Nitrate-Dependent Anaerobic Methane-Oxidizing Enrichment Culture.

PubMed

Gambelli, Lavinia; Guerrero-Cruz, Simon; Mesman, Rob J; Cremers, Geert; Jetten, Mike S M; Op den Camp, Huub J M; Kartal, Boran; Lueke, Claudia; van Niftrik, Laura

2018-02-01

Methane is a very potent greenhouse gas and can be oxidized aerobically or anaerobically through microbe-mediated processes, thus decreasing methane emissions in the atmosphere. Using a complementary array of methods, including phylogenetic analysis, physiological experiments, and light and electron microscopy techniques (including electron tomography), we investigated the community composition and ultrastructure of a continuous bioreactor enrichment culture, in which anaerobic oxidation of methane (AOM) was coupled to nitrate reduction. A membrane bioreactor was seeded with AOM biomass and continuously fed with excess methane. After 150 days, the bioreactor reached a daily consumption of 10 mmol nitrate · liter -1 · day -1 The biomass consisted of aggregates that were dominated by nitrate-dependent anaerobic methane-oxidizing " Candidatus Methanoperedens"-like archaea (40%) and nitrite-dependent anaerobic methane-oxidizing " Candidatus Methylomirabilis"-like bacteria (50%). The " Ca Methanoperedens" spp. were identified by fluorescence in situ hybridization and immunogold localization of the methyl-coenzyme M reductase (Mcr) enzyme, which was located in the cytoplasm. The " Ca Methanoperedens" sp. aggregates consisted of slightly irregular coccoid cells (∼1.5-μm diameter) which produced extruding tubular structures and putative cell-to-cell contacts among each other. " Ca Methylomirabilis" sp. bacteria exhibited the polygonal cell shape typical of this genus. In AOM archaea and bacteria, cytochrome c proteins were localized in the cytoplasm and periplasm, respectively, by cytochrome staining. Our results indicate that AOM bacteria and archaea might work closely together in the process of anaerobic methane oxidation, as the bacteria depend on the archaea for nitrite. Future studies will be aimed at elucidating the function of the cell-to-cell interactions in nitrate-dependent AOM. IMPORTANCE Microorganisms performing nitrate- and nitrite-dependent anaerobic methane oxidation are important in both natural and man-made ecosystems, such as wastewater treatment plants. In both systems, complex microbial interactions take place that are largely unknown. Revealing these microbial interactions would enable us to understand how the oxidation of the important greenhouse gas methane occurs in nature and pave the way for the application of these microbes in wastewater treatment plants. Here, we elucidated the microbial composition, ultrastructure, and physiology of a nitrate-dependent AOM community of archaea and bacteria and describe the cell plan of " Ca Methanoperedens"-like methanotrophic archaea. Copyright © 2018 American Society for Microbiology.

Methane - quick fix or tough target? New methods to reduce emissions.

NASA Astrophysics Data System (ADS)

Nisbet, E. G.; Lowry, D.; Fisher, R. E.; Brownlow, R.

2016-12-01

Methane is a cost-effective target for greenhouse gas reduction efforts. The UK's MOYA project is designed to improve understanding of the global methane budget and to point to new methods to reduce future emissions. Since 2007, methane has been increasing rapidly: in 2014 and 2015 growth was at rates last seen in the 1980s. Unlike 20thcentury growth, primarily driven by fossil fuel emissions in northern industrial nations, isotopic evidence implies present growth is driven by tropical biogenic sources such as wetlands and agriculture. Discovering why methane is rising is important. Schaefer et al. (Science, 2016) pointed out the potential clash between methane reduction efforts and food needs of a rising, better-fed (physically larger) human population. Our own work suggests tropical wetlands are major drivers of growth, responding to weather changes since 2007, but there is no acceptable way to reduce wetland emission. Just as sea ice decline indicates Arctic warming, methane may be the most obvious tracker of climate change in the wet tropics. Technical advances in instrumentation can do much in helping cut urban and industrial methane emissions. Mobile systems can be mounted on vehicles, while drone sampling can provide a 3D view to locate sources. Urban land planning often means large but different point sources are typically clustered (e.g. landfill or sewage plant near incinerator; gas wells next to cattle). High-precision grab-sample isotopic characterisation, using Keeling plots, can separate source signals, to identify specific emitters, even where they are closely juxtaposed. Our mobile campaigns in the UK, Kuwait, Hong Kong and E. Australia show the importance of major single sources, such as abandoned old wells, pipe leaks, or unregulated landfills. If such point sources can be individually identified, even when clustered, they will allow effective reduction efforts to occur: these can be profitable and/or improve industrial safety, for example in the case of gas leaks. Fossil fuels, landfills, waste, and biomass burning emit about 200 Tg/yr, or 35-40% of global methane emissions. Using inexpensive 3D mobile surveys coupled with high-precision isotopic measurement, it should be possible to cut emissions sharply, substantially reducing the methane burden even if tropical biogenic sources increase.

Greenhouse gas, animal performance, and bacterial population structure responses to dietary monensin fed to dairy cows.

PubMed

Hamilton, Scott W; DePeters, Edward J; McGarvey, Jeffery A; Lathrop, Jeremy; Mitloehner, Frank M

2010-01-01

The present study investigated the effects of a feed additive and rumen microbial modifier, monensin sodium (monensin), on selected variables in lactating dairy cows. Monensin fed cows (MON, 600 mg d(-1)) were compared with untreated control cows (CON, 0 mg d(-1)) with respect to the effects of monensin on the production of three greenhouse gases (GHG), methane (CH(4)), nitrous oxide (N(2)O), and carbon dioxide (CO(2)), along with animal performance (dry matter intake; DMI), milk production, milk components, plasma urea nitrogen (PUN), milk urea nitrogen (MUN), and the microbial population structure of fresh feces. Measurements of GHG were collected at Days 14 and 60 in an environmental chamber simulating commercial dairy freestall housing conditions. Milk production and DMI measurements were collected twice daily over the 60-d experimental period; milk components, PUN, and MUN were measured on Days 14 and 60. The microbial population structure of feces from 6 MON and 6 CON cows was examined on three different occasions (Days 14, 30, and 60). Monensin did not affect emissions of methane (CH(4)), nitrous oxide (N(2)O), and carbon dioxide (CO(2)). Over a 24-h period, emissions of CH(4), N(2)O, and CO(2) decreased in both MON and CON groups. Animal performance and the microbial population structure of the animal fresh waste were also unaffected for MON vs. CON cows.

Stable acetate production in extreme-thermophilic (70°C) mixed culture fermentation by selective enrichment of hydrogenotrophic methanogens

NASA Astrophysics Data System (ADS)

Zhang, Fang; Zhang, Yan; Ding, Jing; Dai, Kun; van Loosdrecht, Mark C. M.; Zeng, Raymond J.

2014-06-01

The control of metabolite production is difficult in mixed culture fermentation. This is particularly related to hydrogen inhibition. In this work, hydrogenotrophic methanogens were selectively enriched to reduce the hydrogen partial pressure and to realize efficient acetate production in extreme-thermophilic (70°C) mixed culture fermentation. The continuous stirred tank reactor (CSTR) was stable operated during 100 days, in which acetate accounted for more than 90% of metabolites in liquid solutions. The yields of acetate, methane and biomass in CSTR were 1.5 +/- 0.06, 1.0 +/- 0.13 and 0.4 +/- 0.05 mol/mol glucose, respectively, close to the theoretical expected values. The CSTR effluent was stable and no further conversion occurred when incubated for 14 days in a batch reactor. In fed-batch experiments, acetate could be produced up to 34.4 g/L, significantly higher than observed in common hydrogen producing fermentations. Acetate also accounted for more than 90% of soluble products formed in these fed-batch fermentations. The microbial community analysis revealed hydrogenotrophic methanogens (mainly Methanothermobacter thermautotrophicus and Methanobacterium thermoaggregans) as 98% of Archaea, confirming that high temperature will select hydrogenotrophic methanogens over aceticlastic methanogens effectively. This work demonstrated a potential application to effectively produce acetate as a value chemical and methane as an energy gas together via mixed culture fermentation.

Stable acetate production in extreme-thermophilic (70°C) mixed culture fermentation by selective enrichment of hydrogenotrophic methanogens

PubMed Central

Zhang, Fang; Zhang, Yan; Ding, Jing; Dai, Kun; van Loosdrecht, Mark C. M.; Zeng, Raymond J.

2014-01-01

The control of metabolite production is difficult in mixed culture fermentation. This is particularly related to hydrogen inhibition. In this work, hydrogenotrophic methanogens were selectively enriched to reduce the hydrogen partial pressure and to realize efficient acetate production in extreme-thermophilic (70°C) mixed culture fermentation. The continuous stirred tank reactor (CSTR) was stable operated during 100 days, in which acetate accounted for more than 90% of metabolites in liquid solutions. The yields of acetate, methane and biomass in CSTR were 1.5 ± 0.06, 1.0 ± 0.13 and 0.4 ± 0.05 mol/mol glucose, respectively, close to the theoretical expected values. The CSTR effluent was stable and no further conversion occurred when incubated for 14 days in a batch reactor. In fed-batch experiments, acetate could be produced up to 34.4 g/L, significantly higher than observed in common hydrogen producing fermentations. Acetate also accounted for more than 90% of soluble products formed in these fed-batch fermentations. The microbial community analysis revealed hydrogenotrophic methanogens (mainly Methanothermobacter thermautotrophicus and Methanobacterium thermoaggregans) as 98% of Archaea, confirming that high temperature will select hydrogenotrophic methanogens over aceticlastic methanogens effectively. This work demonstrated a potential application to effectively produce acetate as a value chemical and methane as an energy gas together via mixed culture fermentation. PMID:24920064

Archaea in metazoan diets: implications for food webs and biogeochemical cycling

PubMed Central

Thurber, Andrew R; Levin, Lisa A; Orphan, Victoria J; Marlow, Jeffrey J

2012-01-01

Although the importance of trophic linkages, including ‘top-down forcing', on energy flow and ecosystem productivity is recognized, the influence of metazoan grazing on Archaea and the biogeochemical processes that they mediate is unknown. Here, we test if: (1) Archaea provide a food source sufficient to allow metazoan fauna to complete their life cycle; (2) neutral lipid biomarkers (including crocetane) can be used to identify Archaea consumers; and (3) archaeal aggregates are a dietary source for methane seep metazoans. In the laboratory, we demonstrated that a dorvilleid polychaete, Ophryotrocha labronica, can complete its life cycle on two strains of Euryarchaeota with the same growth rate as when fed bacterial and eukaryotic food. Archaea were therefore confirmed as a digestible and nutritious food source sufficient to sustain metazoan populations. Both strains of Euryarchaeota used as food sources had unique lipids that were not incorporated into O. labronica tissues. At methane seeps, sulfate-reducing bacteria that form aggregations and live syntrophically with anaerobic-methane oxidizing Archaea contain isotopically and structurally unique fatty acids (FAs). These biomarkers were incorporated into tissues of an endolithofaunal dorvilleid polychaete species from Costa Rica (mean bulk δ13C=−92±4‰ polar lipids −116‰) documenting consumption of archaeal-bacterial aggregates. FA composition of additional soft-sediment methane seep species from Oregon and California provided evidence that consumption of archaeal-bacterial aggregates is widespread at methane seeps. This work is the first to show that Archaea are consumed by heterotrophic metazoans, a trophic process we coin as ‘archivory'. PMID:22402398

Archaea in metazoan diets: implications for food webs and biogeochemical cycling.

PubMed

Thurber, Andrew R; Levin, Lisa A; Orphan, Victoria J; Marlow, Jeffrey J

2012-08-01

Although the importance of trophic linkages, including 'top-down forcing', on energy flow and ecosystem productivity is recognized, the influence of metazoan grazing on Archaea and the biogeochemical processes that they mediate is unknown. Here, we test if: (1) Archaea provide a food source sufficient to allow metazoan fauna to complete their life cycle; (2) neutral lipid biomarkers (including crocetane) can be used to identify Archaea consumers; and (3) archaeal aggregates are a dietary source for methane seep metazoans. In the laboratory, we demonstrated that a dorvilleid polychaete, Ophryotrocha labronica, can complete its life cycle on two strains of Euryarchaeota with the same growth rate as when fed bacterial and eukaryotic food. Archaea were therefore confirmed as a digestible and nutritious food source sufficient to sustain metazoan populations. Both strains of Euryarchaeota used as food sources had unique lipids that were not incorporated into O. labronica tissues. At methane seeps, sulfate-reducing bacteria that form aggregations and live syntrophically with anaerobic-methane oxidizing Archaea contain isotopically and structurally unique fatty acids (FAs). These biomarkers were incorporated into tissues of an endolithofaunal dorvilleid polychaete species from Costa Rica (mean bulk δ(13)C=-92±4‰; polar lipids -116‰) documenting consumption of archaeal-bacterial aggregates. FA composition of additional soft-sediment methane seep species from Oregon and California provided evidence that consumption of archaeal-bacterial aggregates is widespread at methane seeps. This work is the first to show that Archaea are consumed by heterotrophic metazoans, a trophic process we coin as 'archivory'.

Effect of microalgae storage conditions on methane yields.

PubMed

Barreiro-Vescovo, Santiago; de Godos, Ignacio; Tomás-Pejó, Elia; Ballesteros, Mercedes; González-Fernández, Cristina

2018-05-01

During the last decade, a lot of research has been focused on identifying the methane yields achievable when using microalgae biomass (fresh and pretreated) as a substrate in anaerobic digestion. Encountered differences are frequently attributed to the different microalgae strains (cell walls and macromolecular profiles) or the different metabolic activities of anaerobic sludge used as inoculum. Nevertheless, under the hypothesis that the state of microalgae upon biomass storage may also play a significant role, this study was designed to evaluate the effect of biomass processing and storage on methane yields and hydrolysis kinetics in batch mode assays. Slight changes in the macromolecular profile distribution of the different tested biomass were observed. Regardless of the time that the biomass was stored, results revealed that frozen biomass doubled the hydrolysis constant and enhanced methane yield by 1.56-fold compared to fresh microalgae biomass (82.4 mL CH 4  g COD in -1 ). Similar enhancement was obtained with the freeze-dried biomass, and slightly lower values were obtained (1.34-fold) for the biomass kept at 4 °C longer than a week. Likewise, the semi-continuously operated reactor fed with microalgae biomass stored for 28 days at 4 °C did not show any effect in terms of methane production, although nitrogen mineralization was higher than expected. Remarkably, the initial stage of the biomass should be carefully considered for comparison purposes with the available literature on batch mode assays. This study highlights the importance of considering how the biomass is stored before the anaerobic digestion process to avoid misleading conclusions.

Efficient production of ethanol from waste paper and the biochemical methane potential of stillage eluted from ethanol fermentation.

PubMed

Nishimura, Hiroto; Tan, Li; Sun, Zhao-Yong; Tang, Yue-Qin; Kida, Kenji; Morimura, Shigeru

2016-02-01

Waste paper can serve as a feedstock for ethanol production due to being rich in cellulose and not requiring energy-intensive thermophysical pretreatment. In this study, an efficient process was developed to convert waste paper to ethanol. To accelerate enzymatic saccharification, pH of waste paper slurry was adjusted to 4.5-5.0 with H2SO4. Presaccharification and simultaneous saccharification and fermentation (PSSF) with enzyme loading of 40 FPU/g waste paper achieved an ethanol yield of 91.8% and productivity of 0.53g/(Lh) with an ethanol concentration of 32g/L. Fed-batch PSSF was used to decrease enzyme loading to 13 FPU/g waste paper by feeding two separate batches of waste paper slurry. Feeding with 20% w/w waste paper slurry increased ethanol concentration to 41.8g/L while ethanol yield decreased to 83.8%. To improve the ethanol yield, presaccharification was done prior to feeding and resulted in a higher ethanol concentration of 45.3g/L, a yield of 90.8%, and productivity of 0.54g/(Lh). Ethanol fermentation recovered 33.2% of the energy in waste paper as ethanol. The biochemical methane potential of the stillage eluted from ethanol fermentation was 270.5mL/g VTS and 73.0% of the energy in the stillage was recovered as methane. Integrating ethanol fermentation with methane fermentation, recovered a total of 80.4% of the energy in waste paper as ethanol and methane. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of a gradually increased load of fish waste silage in co-digestion with cow manure on methane production.

PubMed

Solli, Linn; Bergersen, Ove; Sørheim, Roald; Briseid, Tormod

2014-08-01

This study examined the effects of an increased load of nitrogen-rich organic material on anaerobic digestion and methane production. Co-digestion of fish waste silage (FWS) and cow manure (CM) was studied in two parallel laboratory-scale (8L effective volume) semi-continuous stirred tank reactors (designated R1 and R2). A reactor fed with CM only (R0) was used as control. The reactors were operated in the mesophilic range (37°C) with a hydraulic retention time of 30 days, and the entire experiment lasted for 450 days. The rate of organic loading was raised by increasing the content of FWS in the feed stock. During the experiment, the amount (volume%) of FWS was increased stepwise in the following order: 3% - 6% - 13% - 16%, and 19%. Measurements of methane production, and analysis of volatile fatty acids, ammonium and pH in the effluents were carried out. The highest methane production from co-digestion of FWS and CM was 0.400 L CH4 gVS(-1), obtained during the period with loading of 16% FWS in R2. Compared to anaerobic digestion of CM only, the methane production was increased by 100% at most, when FWS was added to the feed stock. The biogas processes failed in R1 and R2 during the periods, with loadings of 16% and 19% FWS, respectively. In both reactors, the biogas processes failed due to overloading and accumulation of ammonia and volatile fatty acids. Copyright © 2014 Elsevier Ltd. All rights reserved.

Trash-to-Gas: Using Waste Products to Minimize Logistical Mass During Long Duration Space Missions

NASA Technical Reports Server (NTRS)

Hintze, Paul E.; Caraccio, A. J.; Anthony, S. M.; Tsoras, A. N.; Devor, Robert; Captain, James G.; Nur, Mononita

2013-01-01

Just as waste-to-energy processes utilizing municipal landftll and biomass wastes are finding increased terrestrial uses, the Trash-to-Gas (TtG) project seeks to convert waste generated during spaceflight into high value commodities. These include methane for propulsion and water for life support in addition to a variety of other gasses. TtG is part of the Logistic Reduction and Repurposing (LRR) project under the NASA Advanced Exploration Systems Program. The LRR project will enable a largely mission-independent approach to minimize logistics contributions to total mission architecture mass. LRR includes technologies that reduce the amount of consumables that need to be sent to space, repurpose items sent to space, or convert wastes to commodities. Currently, waste generated on the International Space Station is stored inside a logistic module which is de-orbited into Earth's atmosphere for destruction. The waste consists of food packaging, food, clothing and other items. This paper will discuss current results on incineration as a waste processing method. Incineration is part of a two step process to produce methane from waste: first the waste is converted to carbon oxides; second, the carbon oxides are fed to a Sabatier reactor where they are converted to methane. The quantities of carbon dioxide, carbon monoxide, methane and water were measured under the different thermal degradation conditions. The overall carbon conversion efficiency and water recovery are discussed

Biotic Interactions in Microbial Communities as Modulators of Biogeochemical Processes: Methanotrophy as a Model System

PubMed Central

Ho, Adrian; Angel, Roey; Veraart, Annelies J.; Daebeler, Anne; Jia, Zhongjun; Kim, Sang Yoon; Kerckhof, Frederiek-Maarten; Boon, Nico; Bodelier, Paul L. E.

2016-01-01

Microbial interaction is an integral component of microbial ecology studies, yet the role, extent, and relevance of microbial interaction in community functioning remains unclear, particularly in the context of global biogeochemical cycles. While many studies have shed light on the physico-chemical cues affecting specific processes, (micro)biotic controls and interactions potentially steering microbial communities leading to altered functioning are less known. Yet, recent accumulating evidence suggests that the concerted actions of a community can be significantly different from the combined effects of individual microorganisms, giving rise to emergent properties. Here, we exemplify the importance of microbial interaction for ecosystem processes by analysis of a reasonably well-understood microbial guild, namely, aerobic methane-oxidizing bacteria (MOB). We reviewed the literature which provided compelling evidence for the relevance of microbial interaction in modulating methane oxidation. Support for microbial associations within methane-fed communities is sought by a re-analysis of literature data derived from stable isotope probing studies of various complex environmental settings. Putative positive interactions between active MOB and other microbes were assessed by a correlation network-based analysis with datasets covering diverse environments where closely interacting members of a consortium can potentially alter the methane oxidation activity. Although, methanotrophy is used as a model system, the fundamentals of our postulations may be applicable to other microbial guilds mediating other biogeochemical processes. PMID:27602021

Production of biogenic manganese oxides coupled with methane oxidation in a bioreactor for removing metals from wastewater.

PubMed

Matsushita, Shuji; Komizo, Daisuke; Cao, Linh Thi Thuy; Aoi, Yoshiteru; Kindaichi, Tomonori; Ozaki, Noriatsu; Imachi, Hiroyuki; Ohashi, Akiyoshi

2018-03-01

Biogenic manganese oxide (BioMnO x ) can efficiently adsorb various minor metals. The production of BioMnO x in reactors to remove metals during wastewater treatment processes is a promising biotechnological method. However, it is difficult to preferentially enrich manganese-oxidizing bacteria (MnOB) to produce BioMnO x during wastewater treatment processes. A unique method of cultivating MnOB using methane-oxidizing bacteria (MOB) to produce soluble microbial products is proposed here. MnOB were successfully enriched in a methane-fed reactor containing MOB. BioMnO x production during the wastewater treatment process was confirmed. Long-term continual operation of the reactor allowed simultaneous removal of Mn(II), Co(II), and Ni(II). The Co(II)/Mn(II) and Ni(II)/Mn(II) removal ratios were 53% and 19%, respectively. The degree to which Mn(II) was removed indicated that the enriched MnOB used utilization-associated products and/or biomass-associated products. Microbial community analysis revealed that methanol-oxidizing bacteria belonging to the Hyphomicrobiaceae family played important roles in the oxidation of Mn(II) by using utilization-associated products. Methane-oxidizing bacteria were found to be inhibited by MnO 2 , but the maximum Mn(II) removal rate was 0.49 kg m -3  d -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of pre-acclimation of granular activated carbon on microbial electrolysis cell startup and performance.

PubMed

LaBarge, Nicole; Yilmazel, Yasemin Dilsad; Hong, Pei-Ying; Logan, Bruce E

2017-02-01

Microbial electrolysis cells (MECs) can generate methane by fixing carbon dioxide without using expensive catalysts, but the impact of acclimation procedures on subsequent performance has not been investigated. Granular activated carbon (GAC) was used to pre-enrich electrotrophic methanogenic communities, as GAC has been shown to stimulate direct transfer of electrons between different microbial species. MEC startup times using pre-acclimated GAC were improved compared to controls (without pre-acclimation or without GAC), and after three fed batch cycles methane generation rates were similar (P>0.4) for GAC acclimated to hydrogen (22±9.3nmolcm -3 d -1 ), methanol (25±9.7nmolcm -3 d -1 ), and a volatile fatty acid (VFA) mix (22±11nmolcm -3 d -1 ). However, MECs started with GAC but no pre-acclimation had lower methane generation rates (13±4.1nmolcm -3 d -1 ), and MECs without GAC had the lowest rates (0.7±0.8nmolcm -3 d -1 after cycle 2). Microbes previously found in methanogenic MECs, or previously shown to be capable of exocellular electron transfer, were enriched on the GAC. Pre-acclimation using GAC is therefore a simple approach to enrich electroactive communities, improve methane generation rates, and decrease startup times in MECs. Copyright © 2016 Elsevier B.V. All rights reserved.

Trash-to-Gas: Using Waste Products to Minimize Logistical Mass During Long Duration Space Missions

NASA Technical Reports Server (NTRS)

Hintze, Paul. E.; Caraccio, Anne J.; Anthony, Stephen M.; Tsoras, Alexandra N.; Nur, Monoita; Devor, Robert; Captain, James G.

2013-01-01

Just as waste-to-energy processes utilizing municipal landftll and biomass wastes are finding increased terrestrial uses, the Trash-to-Gas (TtG) project seeks to convert waste generated during spaceflight into high value commodities. These include methane for propulsion and water for life support in addition to a variety of other gasses. TtG is part of the Logistic Reduction and Repurposing (LRR) project under the NASA Advanced Exploration Systems Program. The LRR project will enable a largely mission-independent approach to minimize logistics contributions to total mission architecture mass. LRR includes technologies that reduce the amount of consumables that need to be sent to space, repurpose items sent to space, or convert wastes to commodities. Currently, waste generated on the International Space Station is stored inside a logistic module which is de-orbited into Earth's atmosphere for destruction. The waste consists of food packaging, food, clothing and other items. This paper will discuss current results on incineration as a waste processing method. Incineration is part of a two step process to produce methane from waste: first the waste is converted to carbon oxides; second, the carbon oxides are fed to a Sabatier reactor where they are converted to methane. The quantities of carbon dioxide, carbon monoxide, methane and water were measured under the different thermal degradation conditions. The overall carbon conversion efficiency and water recovery are discussed.

High solid fed-batch butanol fermentation with simultaneous product recovery: part II - process integration.

USDA-ARS?s Scientific Manuscript database

In these studies liquid hot water (LHW) pretreated and enzymatically hydrolyzed Sweet Sorghum Bagasse (SSB) hydrolyzates were fermented in a fed-batch reactor. As reported in the preceding paper, the culture was not able to ferment the hydrolyzate I in a batch process due to presence of high level o...

All-solid-state Z-scheme system arrays of Fe2V4O13/RGO/CdS for visible light-driving photocatalytic CO2 reduction into renewable hydrocarbon fuel.

PubMed

Li, Ping; Zhou, Yong; Li, Haijin; Xu, Qinfeng; Meng, Xianguang; Meng, Xiangguang; Wang, Xiaoyong; Xiao, Min; Zou, Zhigang

2015-01-14

An all-solid-state Z-scheme system array consisting of an Fe2V4O13 nanoribbon (NR)/reduced graphene oxide (RGO)/CdS nanoparticle grown on the stainless-steel mesh was rationally designed for photoconversion of gaseous CO2 into renewable hydrocarbon fuels (methane: CH4).

U.S. Air Force Environmental Assessment, Add To and Alter Type III Hydrant Fueling System, Tinker Air Force Base, Oklahoma

DTIC Science & Technology

2011-12-01

burning of fossil fuels (e.g., oil , natural gas , coal), solid waste decay, and trees and wood products and also as a result of chemical reactions...to negative GHG effects. Methane. CH4 is a GHG that is emitted during the production and transport of coal, natural gas , and oil . Methane...the pump station (Facility 486); Control Room (Facility 487); and the oil -water separator (Facility 488). • Construction of a new Type III pump house

Investigation into the effects of sulfur on syngas reforming inside a solid oxide fuel cell

NASA Astrophysics Data System (ADS)

Li, Ting Shuai; Xu, Min; Gao, Chongxin; Wang, Baoqing; Liu, Xiyun; Li, Baihai; Wang, Wei Guo

2014-07-01

The electrochemical performance and long-term durability of a solid oxide fuel cell have been evaluated with a simulated coal syngas containing 2 ppm H2S as fuel. The resulting impedance spectra indicate that no observable power loss is caused by the addition of 2 ppm H2S, and the cell shows stability of nearly 500 h at 0.625 A cm-2. The composition of mixed gas is analyzed both at a current load of 0.625 A cm-2 and open circuit state. Hydrogen and carbon monoxide are directly consumed as fuels at the anode side, whereas methane stays unchanged during the operation. It seems the internal carbohydrate reforming and impurity poisoning interacts and weakens the poisoning effects. The oxidation of H2 and the water gas shift reaction take advantages over methane reforming at the cell operational conditions.

Effect of initial bulk density on high-solids anaerobic digestion of MSW: General mechanism.

PubMed

Caicedo, Luis M; Wang, Hongtao; Lu, Wenjing; De Clercq, Djavan; Liu, Yanjun; Xu, Sai; Ni, Zhe

2017-06-01

Initial bulk density (IBD) is an important variable in anaerobic digestion since it defines and optimizes the treatment capacity of a system. This study reveals the mechanism on how IBD might affect anaerobic digestion of waste. Four different IBD values: D 1 (500-700kgm -3 ), D 2 (900-1000kgm -3 ), D 3 (1100-1200kgm -3 ) and D 4 (1200-1400kgm -3 ) were set and tested over a period of 90days in simulated landfill reactors. The main variables affected by the IBD are the methane generation, saturation degree, extraction of organic matter, and the total population of methanogens. The study identified that IBD >1000kgm -3 may have significant effect on methane generation, either prolonging the lag time or completely inhibiting the process. This study provides a new understanding of the anaerobic digestion process in saturated high-solids systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimizing the performance of microbial fuel cells fed a combination of different synthetic organic fractions in municipal solid waste.

PubMed

Pendyala, Brahmaiah; Chaganti, Subba Rao; Lalman, Jerald A; Heath, Daniel D

2016-03-01

The objective of this study was to establish the impact of different steam exploded organic fractions in municipal solid waste (MSW) on electricity production using microbial fuel cells (MFCs). In particular, the influence of individual steam exploded liquefied waste components (food waste (FW), paper-cardboard waste (PCW) and garden waste (GW)) and their blends on chemical oxygen demand (COD) removal, columbic efficiency (CE) and microbial diversity was examined using a mixture design. Maximum power densities from 0.56 to 0.83 W m(-2) were observed for MFCs fed with different feedstocks. The maximum COD removed and minimum CE were observed for a GW feed. However, a reverse trend (minimum COD removed and maximum CE) was observed for the FW feed. A maximum COD removal (78%) accompanied with a maximum CE (24%) was observed for a combined feed of FW, PCW plus GW in a 1:1:1 ratio. Lactate, the major byproduct detected, was unutilized by the anodic biofilm community. The organic fraction of municipal solid waste (OFMSW) could serve as a potential feedstock for electricity generation in MFCs; however, elevated protein levels will lead to reduced COD removal. The microbial communities in cultures fed FW and PCW was highly diversified; however, the communities in cultures fed FW or a feed mixture containing high FW levels were similar and dominated by Bacteroidetes and β-proteobacteria. Copyright © 2016 Elsevier Ltd. All rights reserved.

Model calibration and validation for OFMSW and sewage sludge co-digestion reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esposito, G., E-mail: giovanni.esposito@unicas.it; Frunzo, L., E-mail: luigi.frunzo@unina.it; Panico, A., E-mail: anpanico@unina.it

2011-12-15

Highlights: > Disintegration is the limiting step of the anaerobic co-digestion process. > Disintegration kinetic constant does not depend on the waste particle size. > Disintegration kinetic constant depends only on the waste nature and composition. > The model calibration can be performed on organic waste of any particle size. - Abstract: A mathematical model has recently been proposed by the authors to simulate the biochemical processes that prevail in a co-digestion reactor fed with sewage sludge and the organic fraction of municipal solid waste. This model is based on the Anaerobic Digestion Model no. 1 of the International Watermore » Association, which has been extended to include the co-digestion processes, using surface-based kinetics to model the organic waste disintegration and conversion to carbohydrates, proteins and lipids. When organic waste solids are present in the reactor influent, the disintegration process is the rate-limiting step of the overall co-digestion process. The main advantage of the proposed modeling approach is that the kinetic constant of such a process does not depend on the waste particle size distribution (PSD) and rather depends only on the nature and composition of the waste particles. The model calibration aimed to assess the kinetic constant of the disintegration process can therefore be conducted using organic waste samples of any PSD, and the resulting value will be suitable for all the organic wastes of the same nature as the investigated samples, independently of their PSD. This assumption was proven in this study by biomethane potential experiments that were conducted on organic waste samples with different particle sizes. The results of these experiments were used to calibrate and validate the mathematical model, resulting in a good agreement between the simulated and observed data for any investigated particle size of the solid waste. This study confirms the strength of the proposed model and calibration procedure, which can thus be used to assess the treatment efficiency and predict the methane production of full-scale digesters.« less

Anaerobic digestion of sulfate-acidified cattle slurry: One-stage vs. two-stage.

PubMed

Moset, Veronica; Ottosen, Lars Ditlev Mørck; Xavier, Cristiane de Almeida Neves; Møller, Henrik Bjarne

2016-05-15

Two strategies to include acidified cattle manure (AcCM) in co-digestion with normal cattle manure (CM) are presented in this work. The strategies are a single thermophilic (50 °C) continuous stirred tank reactor (CSTR) anaerobic digestion and a two-step (65 °C + 50 °C) CSTR process. In both strategies, two different inclusion levels of H2SO4-acidified CM (10% and 20%) in co-digestion with normal CM were tested and compared with a control CSTR fed only CM. Important enhancement of methane (CH4) yield and solid reductions were observed in the thermophilic one-step CSTR working with 10% AcCM. However, a higher inclusion level of AcCM (20%) caused volatile fatty acid accumulation in the reactor and a more than 30% reduction in CH4 production. In terms of CH4 production, when 10% of AcCM was co-digested with 90% of CM, the two-step anaerobic co-digestion yielded less than the single step. During the first step of the two-step CSTR process, acidogenesis and a partial sulfate reduction were achieved. However, sulfide stripping between the first and the second step must be promoted in order to advance this technology. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhanced sludge reduction in septic tanks by increasing temperature.

PubMed

Pussayanavin, Tatchai; Koottatep, Thammarat; Eamrat, Rawintra; Polprasert, Chongrak

2015-01-01

Septic tanks in most developing countries are constructed without drainage trenches or leaching fields to treat toilet wastewater and /or grey water. Due to the short hydraulic retention time, effluents of these septic tanks are still highly polluted, and there is usually high accumulation of septic tank sludge or septage containing high levels of organics and pathogens that requires frequent desludging and subsequent treatment. This study aimed to reduce sludge accumulation in septic tanks by increasing temperatures of the septic tank content. An experimental study employing two laboratory-scale septic tanks fed with diluted septage and operating at temperatures of 40 and 30°C was conducted. At steady-state conditions, there were more methanogenic activities occurring in the sludge layer of the septic tank operating at the temperature of 40°C, resulting in less total volatile solids (TVS) or sludge accumulation and more methane (CH4) production than in the unit operating at 30°C. Molecular analysis found more abundance and diversity of methanogenic microorganisms in the septic tank sludge operating at 40°C than at 30°C. The reduced TVS accumulation in the 40°C septic tank would lengthen the period of septage removal, resulting in a cost-saving in desluging and septage treatment. Cost-benefit analysis of increasing temperatures in septic tanks was discussed.

Anaerobic digestion of macroalgae: methane potentials, pre-treatment, inhibition and co-digestion.

PubMed

Nielsen, H B; Heiske, S

2011-01-01

In the present study we tested four macroalgae species--harvested in Denmark--for their suitability of bioconversion to methane. In batch experiments (53 degrees C) methane yields varied from 132 ml g volatile solids(-1) (VS) for Gracillaria vermiculophylla, 152 mi gVS(-1) for Ulva lactuca, 166 ml g VS(-1) for Chaetomorpha linum and 340 ml g VS(-1) for Saccharina latissima following 34 days of incubation. With an organic content of 21.1% (1.5-2.8 times higher than the other algae) S. latissima seems very suitable for anaerobic digestion. However, the methane yields of U. lactuca, G. vermiculophylla and C. linum could be increased with 68%, 11% and 17%, respectively, by pretreatment with maceration. U. lactuca is often observed during 'green tides' in Europe and has a high cultivation potential at Nordic conditions. Therefore, U. lactuca was selected for further investigation and co-digested with cattle manure in a lab-scale continuously stirred tank reactor. A 48% increase in methane production rate of the reactor was observed when the concentration of U. lactuca in the feedstock was 40% (VS basis). Increasing the concentration to 50% had no further effect on the methane production, which limits the application of this algae at Danish centralized biogas plant.

Methane production and hydrolysis kinetics in the anaerobic degradation of wastewater screenings.

PubMed

Cadavid-Rodríguez, L S; Horan, N

2013-01-01

Anaerobic biodegradability and hydrolysis rates of wastewater screenings were determined using the biochemical methane potential test at 37 °C. The extent and rate of screenings conversion to methane of this complex and particulate substrate were investigated and since two stages of hydrolysis were identified, corresponding to the different types of materials in screenings, a linear and non-linear model was used. No accumulation of intermediary products was observed and so it was possible to use the methane production rate and a linear model to estimate the hydrolysis rate in the first phase of hydrolysis. The measured values of 0.061-0.127 d(-1) are in the range reported for other comparable organic wastes. It was also observed that the inoculum-to-substrate ratio has a large impact on methane production rate of screenings. The difference in biodegradation rates from the materials in screenings and the overall hydrolysis could be represented by the modified Gompertz non-linear model which was able to describe the methane production rate of screenings with a high confidence. Screenings were found to have 52% biodegradability on average and this shows the potential for volatile solids destruction. A two-stage process with an improved hydrolysis rate is proposed to ensure that the full potential of the material is exploited.

Simulation of municipal solid waste degradation in aerobic and anaerobic bioreactor landfills.

PubMed

Patil, Bhagwan Shamrao; C, Agnes Anto; Singh, Devendra Narain

2017-03-01

Municipal solid waste generation is huge in growing cities of developing nations such as India, owing to the rapid industrial and population growth. In addition to various methods for treatment and disposal of municipal solid waste (landfills, composting, bio-methanation, incineration and pyrolysis), aerobic/anaerobic bioreactor landfills are gaining popularity for economical and effective disposal of municipal solid waste. However, efficiency of municipal solid waste bioreactor landfills primarily depends on the municipal solid waste decomposition rate, which can be accelerated through monitoring moisture content and temperature by using the frequency domain reflectometry probe and thermocouples, respectively. The present study demonstrates that these landfill physical properties of the heterogeneous municipal solid waste mass can be monitored using these instruments, which facilitates proper scheduling of the leachate recirculation for accelerating the decomposition rate of municipal solid waste.

GM(1,N) method for the prediction of anaerobic digestion system and sensitivity analysis of influential factors.

PubMed

Ren, Jingzheng

2018-01-01

Anaerobic digestion process has been recognized as a promising way for waste treatment and energy recovery in a sustainable way. Modelling of anaerobic digestion system is significantly important for effectively and accurately controlling, adjusting, and predicting the system for higher methane yield. The GM(1,N) approach which does not need the mechanism or a large number of samples was employed to model the anaerobic digestion system to predict methane yield. In order to illustrate the proposed model, an illustrative case about anaerobic digestion of municipal solid waste for methane yield was studied, and the results demonstrate that GM(1,N) model can effectively simulate anaerobic digestion system at the cases of poor information with less computational expense. Copyright © 2017 Elsevier Ltd. All rights reserved.

Methane Post-Processing for Oxygen Loop Closure

NASA Technical Reports Server (NTRS)

Greenwood, Zachary W.; Abney, Morgan B.; Miller, Lee

2016-01-01

State-of-the-art United States Atmospheric Revitalization carbon dioxide (CO2) reduction is based on the Sabatier reaction process, which recovers approximately 50% of the oxygen (O2) from crew metabolic CO2. Oxygen recovery from carbon dioxide is constrained by the limited availability of reactant hydrogen. Post-processing of methane to recover hydrogen with the Umpqua Research Company Plasma Pyrolysis Assembly (PPA) has the potential to further close the Atmospheric Revitalization oxygen loop. The PPA decomposes methane into hydrogen and hydrocarbons, predominantly acetylene, and a small amount of solid carbon. The hydrogen must then be purified before it can be recycled for additional oxygen recovery. Long duration testing and evaluation of a four crew-member sized PPA and a discussion of hydrogen recycling system architectures are presented.

Dissociation behavior of methane--ethane mixed gas hydrate coexisting structures I and II.

PubMed

Kida, Masato; Jin, Yusuke; Takahashi, Nobuo; Nagao, Jiro; Narita, Hideo

2010-09-09

Dissociation behavior of methane-ethane mixed gas hydrate coexisting structures I and II at constant temperatures less than 223 K was studied with use of powder X-ray diffraction and solid-state (13)C NMR techniques. The diffraction patterns at temperatures less than 203 K showed both structures I and II simultaneously convert to Ih during the dissociation, but the diffraction pattern at temperatures greater than 208 K showed different dissociation behavior between structures I and II. Although the diffraction peaks from structure II decreased during measurement at constant temperatures greater than 208 K, those from structure I increased at the initial step of dissociation and then disappeared. This anomalous behavior of the methane-ethane mixed gas hydrate coexisting structures I and II was examined by using the (13)C NMR technique. The (13)C NMR spectra revealed that the anomalous behavior results from the formation of ethane-rich structure I. The structure I hydrate formation was associated with the dissociation rate of the initial methane-ethane mixed gas hydrate.

Effect of alkaline pretreatment on anaerobic digestion of olive mill solid waste.

PubMed

Pellera, Frantseska-Maria; Santori, Sofia; Pomi, Raffaella; Polettini, Alessandra; Gidarakos, Evangelos

2016-12-01

The present study evaluates the influence of alkaline (NaOH) pretreatment on anaerobic digestion of olive pomace. Batch hydrolysis experiments with different NaOH dosages, process durations and temperatures were conducted, in which the variation of olive pomace solubilization in the liquid phase was investigated. The effect of pretreatment on anaerobic digestion was studied through biochemical methane potential assays. The results demonstrated the effectiveness of the NaOH pretreatment in improving olive pomace solubilization as well as its biodegradability. Maximum specific methane yields were achieved at different NaOH dosages depending on the pretreatment temperature. Consequently, it was concluded that the two operating parameters of the pretreatment stage (NaOH dosage and temperature) may exert a joint effect on substrate biodegradability and methane yields. The highest methane yield (242NmLCH 4 /gVS) was obtained for the material pretreated at 90°C, at a dosage of 1mmol/gVS (4% of VS). Copyright © 2016 Elsevier Ltd. All rights reserved.

Microbial community structure in a thermophilic aerobic digester used as a sludge pretreatment process for the mesophilic anaerobic digestion and the enhancement of methane production.

PubMed

Jang, Hyun Min; Park, Sang Kyu; Ha, Jeong Hyub; Park, Jong Moon

2013-10-01

An effective two-stage sewage sludge digestion process, consisting of thermophilic aerobic digestion (TAD) followed by mesophilic anaerobic digestion (MAD), was developed for efficient sludge reduction and methane production. Using TAD as a biological pretreatment, the total volatile suspended solid reduction (VSSR) and methane production rate (MPR) in the MAD reactor were significantly improved. According to denaturing gradient gel electrophoresis (DGGE) analysis, the results indicated that the dominant bacteria species such as Ureibacillus thermophiles and Bacterium thermus in TAD were major routes for enhancing soluble organic matter. TAD pretreatment using a relatively short SRT of 1 day showed highly increased soluble organic products and positively affected an increment of bacteria populations which performed interrelated microbial metabolisms with methanogenic species in the MAD; consequently, a quantitative real-time PCR indicated greatly increased Methanosarcinales (acetate-utilizing methanogens) in the MAD, resulting in enhanced methane production. Copyright © 2013 Elsevier Ltd. All rights reserved.

Stabilization of Quinapril by Incorporating Hydrogen Bonding Interactions

PubMed Central

Roy, B. N.; Singh, G. P.; Godbole, H. M.; Nehate, S. P.

2009-01-01

In the present study stability of various known solvates of quinapril hydrochloride has been compared with nitromethane solvate. Nitromethane solvate was found to be more stable compared to other known solvates. Single crystal X-ray diffraction analysis of quinapril nitromethane solvate shows intermolecular hydrogen bonding between quinapril molecule and nitromethane. Stabilization of quinapril by forming strong hydrogen bonding network as in case of co-crystals was further studied by forming co-crystal with tris(hydroxymethyl)amino methane. Quinapril free base forms a stable salt with tris(hydroxymethyl)amino methane not reported earlier. Quinapril tris(hydroxymethyl)amino methane salt found to be stable even at 80° for 72 h i.e. hardly any formation of diketopiperazine and diacid impurity. As expected single crystal X-ray diffraction analysis reveals tris(hydroxymethyl)amino methane salt of quinapril shows complex hydrogen bonding network between the two entities along with ionic bond. The properties of this stable salt - stable in solid as well as solution phase, might lead to an alternate highly stable formulation. PMID:20502545

Optimizing the thermophilic hydrolysis of grass silage in a two-phase anaerobic digestion system.

PubMed

Orozco, A M; Nizami, A S; Murphy, J D; Groom, E

2013-09-01

Thermophilic hydrolysis of grass silage (GS) at 55 °C with organic loading rates (OLRs) of 6.5, 5, 2.5 and 1.0 kg VS m(-3) days(-1) and hydraulic retention times (HRT) of 10, 6, 4 and 2 days were evaluated in 12 glass bioreactors side by side. The hydrolytic process was measured by variation in pH, volatile solids (VS), VS destruction, soluble chemical oxygen demand (sCOD), hydrolysis and acidification yields. Biological methane potential (BMP) assays were carried out to measure the upper limit for methane production of grass silage with different hydrolytic pretreatments at mesophilic temperature (37 °C). The optimum methane yield of 368 LN CH4 kg(-1) VS was obtained at an OLR of 1 kg VS m(-3)days(-1) and a HRT of 4 days, showing an increase of 30% in the methane potential in comparison to non-hydrolysed GS. Copyright © 2013 Elsevier Ltd. All rights reserved.

Anaerobic digestion of pressed off leachate from the organic fraction of municipal solid waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nayono, Satoto E.; Institute of Biology for Engineers and Biotechnology of Wastewater, University of Karlsruhe, Am Fasanengarten, 76131 Karlsruhe; Winter, Josef, E-mail: josef.winter@iba.uka.d

2010-10-15

A highly polluted liquid ('press water') was obtained from the pressing facility for the organic fraction of municipal solid waste in a composting plant. Methane productivity of the squeezed-off leachate was investigated in batch assays. To assess the technical feasibility of 'press water' as a substrate for anaerobic digestion, a laboratory-scale glass column reactor was operated semi-continuously at 37 {sup o}C. A high methane productivity of 270 m{sup -3} CH{sub 4} ton{sup -1} COD{sub added} or 490 m{sup -3} CH{sub 4} ton{sup -1} VS{sub added} was achieved in the batch experiment. The semi-continuously run laboratory-scale reactor was initially operated atmore » an organic loading rate of 10.7 kg COD m{sup -3} d{sup -1}. The loading was increased to finally 27.7 kg COD m{sup -3} d{sup -1}, corresponding to a reduction of the hydraulic retention time from initially 20 to finally 7.7 days. During the digestion, a stable elimination of organic material (measured as COD elimination) of approximately 60% was achieved. Linearly with the increment of the OLR, the volumetric methane production of the reactor increased from 2.6 m{sup 3} m{sub reactor}{sup -3} d{sup -1} to 7.1 m{sup 3} m{sub reactor}{sup -3} d{sup -1}. The results indicated that 'press water' from the organic fraction of municipal solid waste was a suitable substrate for anaerobic digestion which gave a high biogas yield even at very high loading rates.« less

Effect of solid feed on energy and protein utilization in milk-fed veal calves.

PubMed

Labussiere, E; Dubois, S; van Milgen, J; Bertrand, G; Noblet, J

2009-03-01

Little knowledge on the digestive and metabolic utilization of solid feed in veal calves is available. The objectives of the study were to determine the effects of 2 solid feeds offered at 2 feeding levels (FL90 and FL105) in addition to a milk replacer on heat production (HP) and protein and fat deposition in veal calves. Sixteen calves (148.0 +/- 3.7 kg) received milk replacer (75% of a reference DE allowance) and solid feeds that consisted of corn grain and pelleted hydrolyzed wheat gluten without (CO) or with (CS) chopped wheat straw. The solid feed supply provided 15 or 30% of the reference DE allowance to achieve FL90 or FL105, resulting in 4 treatments: CO90, CS90, CO105, and CS105. A fifth treatment consisted of using the milk replacer alone at FL90 (treatment M90) and was measured in 4 other calves. All calves were kept individually for 7 d in a respiration chamber to estimate energy and N balances and fasting HP. The digestibility coefficients of DM, OM, GE, and major nutrients were at least 94% for M90 and decreased when solid feed was added (P < 0.05). Methane production was negligible in M90 calves and increased when solid feed was given (ranging 8 to 23 L/d between CO90 and CS105, P < 0.01), indicative of ruminal fermentation. The provision of increasing amounts of solid feed decreased urinary energy in connection with a tendency (P = 0.09) for a reduction of urinary glucose excretion. The metabolizability of DE was greater with the milk replacer (95.6%) and decreased when straw was added (P < 0.01). Neither CO90 or CS90 affected HP and total energy retention (P > 0.05). Dietary treatment had no effect (P > 0.05) on activity HP (53 kJ/kg of BW(0.85) daily) but did affect thermic effect of feeding; efficiency of utilizing ME for maintenance and growth was greatest for the M90 calves (84.5%, P = 0.02). Fasting HP tended (P = 0.09) to increase at the greatest FL (308 vs. 298 kJ/kg of BW(0.85) daily). Maintenance ME requirement increased (P = 0.04) from 364 to 382 kJ/kg of BW(0.85) daily when feeding level increased (P = 0.04) but was not affected by ingestion of solid feed. The provision of solid feed to veal calves was associated with a reduced efficiency of N retention (P = 0.04), and energy retained as protein tended to decrease (P = 0.08), probably as a result of an imbalanced AA supply of the solid feeds. The data were used to calculate the energy contents of solid feed. The utilization of energy from solid feed differed from that of milk replacer.

Emerging trends in breastfeeding practices in Singaporean Chinese women: findings from a population-based study.

PubMed

Hornbeak, Dana M; Dirani, Mohamed; Sham, Wai Kit; Li, Jialiang; Young, Terri L; Wong, Tien Yin; Chong, Yap Seng; Saw, Seang Mei

2010-02-01

This study records the prevalence and patterns of breastfeeding in Singaporean Chinese mothers who gave birth between 2000 and 2008. The Strabismus, Amblyopia and Refractive Error in Singaporean Children (STARS) study is a population-based survey conducted in South-Western Singapore. Disproportionate random sampling by 6-month age groups of Chinese children born from 2000 to 2008 was performed. The mothers (n = 3009) completed a standard questionnaire which recorded the initiation, content, method and duration of breastfeeding. World Health Organization (WHO) definitions for feeding content were used: Replacement (exclusive commercial formula or any liquid or solid/semi-solid food, excluding breast milk), Complementary (breast milk, solid/semi-solid foods, and any non-human liquid), and Exclusive (breast milk only, without additional food, drink or water). STARS-specific definitions for feeding method were used: Expressed (breast milk only fed via bottle, with no additional food or non-human liquid), Combination (breast milk and non-breast milk, fed via bottle and breast), and Direct (breast milk only fed via breast). Breastfeeding initiation (overall prevalence 77.0%) and duration increased over time, and were independently associated with higher maternal education: in 2000 and 2001, 68.6% of mothers initiated breastfeeding and 12.9% breast fed for or=6 months, vs 90.9% and 35.3%, respectively, of university-educated women (P <0.001). Expressed, Combination and Complementary feeding also increased, while Replacement feeding decreased (P <0.001). There was no difference in breastfeeding patterns by the child's gender. In a population-based sample of Singaporean Chinese mothers giving birth from 2000 to 2008, breastfeeding initiation and duration increased over time and were independently associated with higher maternal education. This increase was associated with increased milk expression and complementary feeding. Thus awareness of breastfeeding benefits is rising in Singapore, but future health policies may need to target less-educated mothers.

Associations of breast-feeding patterns and introduction of solid foods with childhood bone mass: The Generation R Study.

PubMed

van den Hooven, Edith H; Gharsalli, Mounira; Heppe, Denise H M; Raat, Hein; Hofman, Albert; Franco, Oscar H; Rivadeneira, Fernando; Jaddoe, Vincent W V

2016-03-28

Breast-feeding has been associated with later bone health, but results from previous studies are inconsistent. We examined the associations of breast-feeding patterns and timing of introduction of solids with bone mass at the age of 6 years in a prospective cohort study among 4919 children. We collected information about duration and exclusiveness of breast-feeding and timing of introduction of any solids with postnatal questionnaires. A total body dual-energy X-ray absorptiometry scan was performed at 6 years of age, and bone mineral density (BMD), bone mineral content (BMC), area-adjusted BMC (aBMC) and bone area (BA) were analysed. Compared with children who were ever breast-fed, those never breast-fed had lower BMD (-4·62 mg/cm2; 95 % CI -8·28, -0·97), BMC (-8·08 g; 95 % CI -12·45, -3·71) and BA (-7·03 cm2; 95 % CI -12·55, -1·52) at 6 years of age. Among all breast-fed children, those who were breast-fed non-exclusively in the first 4 months had higher BMD (2·91 mg/cm2; 95 % CI 0·41, 5·41) and aBMC (3·97 g; 95 % CI 1·30, 6·64) and lower BA (-4·45 cm2; 95 % CI -8·28, -0·61) compared with children breast-fed exclusively for at least 4 months. Compared with introduction of solids between 4 and 5 months, introduction <4 months was associated with higher BMD and aBMC, whereas introduction between 5 and 6 months was associated with lower aBMC and higher BA. Additional adjustment for infant vitamin D supplementation did not change the results. In conclusion, results from the present study suggest that ever breast-feeding compared with never breast-feeding is associated with higher bone mass in 6-year-old children, but exclusive breast-feeding for 4 months or longer was not positively associated with bone outcomes.