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Sample records for anaerobic process effects

  1. Anaerobic Process.

    PubMed

    Yang, Qian; Ju, Mei-Ting; Li, Wei-Zun; Liu, Le; Wang, Yan-Nan; Chang, Chein-Chi

    2016-10-01

    A review of the literature published in 2015 on the focus of Anaerobic Process. It is divided into the following sections. Pretreatment Organic waste Multiple-stage co-digestion Process Methodology and Technology. PMID:27620085

  2. Dynamics of the anaerobic process: effects of volatile fatty acids.

    PubMed

    Pind, Peter F; Angelidaki, Irini; Ahring, Birgitte K

    2003-06-30

    A complex and fast dynamic response of the anaerobic biogas system was observed when the system was subjected to pulses of volatile fatty acids (VFAs). It was shown that a pulse of specific VFAs into a well-functioning continuous stirred tank reactor (CSTR) system operating on cow manure affected both CH(4) yield, pH, and gas production and that a unique reaction pattern was seen for the higher VFAs as a result of these pulses. In this study, two thermophilic laboratory reactors were equipped with a novel VFA-sensor for monitoring specific VFAs online. Pulses of VFAs were shown to have a positive effect on process yield and the levels of all VFA were shown to stabilize at a lower level after the biomass had been subjected to several pulses. The response to pulses of propionate or acetate was different from the response to butyrate, iso-butyrate, valerate, or iso-valerate. High concentrations of propionate affected the degradation of all VFAs, while a pulse of acetate affected primarily the degradation of iso-valerate or 2-methylbutyrate. Pulses of n-butyrate, iso-butyrate, and iso-valerate yielded only acetate, while degradation of n-valerate gave both propionate and acetate. Product sensitivity or inhibition was shown for the degradation of all VFAs tested. Based on the results, it was concluded that measurements of all specific VFAs are important for control purposes and increase and decrease in a specific VFA should always be evaluated in close relationship to the conversion of other VFAs and the history of the reactor process. It should be pointed out that the observed dynamics of VFA responses were based on hourly measurements, meaning that the response duration was much lower than the hydraulic retention time, which exceeds several days in anaerobic CSTR systems.

  3. The anaerobic digestion process

    SciTech Connect

    Rivard, C.J.; Boone, D.R.

    1996-01-01

    The microbial process of converting organic matter into methane and carbon dioxide is so complex that anaerobic digesters have long been treated as {open_quotes}black boxes.{close_quotes} Research into this process during the past few decades has gradually unraveled this complexity, but many questions remain. The major biochemical reactions for forming methane by methanogens are largely understood, and evolutionary studies indicate that these microbes are as different from bacteria as they are from plants and animals. In anaerobic digesters, methanogens are at the terminus of a metabolic web, in which the reactions of myriads of other microbes produce a very limited range of compounds - mainly acetate, hydrogen, and formate - on which the methanogens grow and from which they form methane. {open_quotes}Interspecies hydrogen-transfer{close_quotes} and {open_quotes}interspecies formate-transfer{close_quotes} are major mechanisms by which methanogens obtain their substrates and by which volatile fatty acids are degraded. Present understanding of these reactions and other complex interactions among the bacteria involved in anaerobic digestion is only now to the point where anaerobic digesters need no longer be treated as black boxes.

  4. Alkaline and acid hydrolytic processes in aerobic and anaerobic sludges: effect on total EPS and fractions.

    PubMed

    Cassini, S T; Andrade, M C E; Abreu, T A; Keller, R; Gonçalves, R F

    2006-01-01

    Sludge samples from an upflow anaerobic sludge blanket (UASB) reactor and four submerged aerated biofilters (BFs) of a wastewater treatment plant (1,000 inhab.) were processed at bench scale by alkaline and acid hydrolysis with the objective to evaluate the organic matter solubilization, volatile solids (VS) destruction and the effect of hydrolytic processes on the extracellular polymeric substances (EPS) fraction of the sludge samples. The results showed that alkaline hydrolysis of sludge samples treatment with 1.0% total solids (TS) using NaOH 20 meq L(-1) was more efficient on organic matter solubilization and VS destruction than acid hydrolysis. The EPS sludge content was also affected by the alkaline treatment of anaerobic sludge samples. The EPS concentrations (mg EPS/gVSS) on the anaerobic sludge after the alkaline treatment were significantly lowered according to sample height in the UASB reactor. Data indicated that the EPS sludge fraction is the main component affected by the alkaline hydrolytic process of anaerobic sludge samples. PMID:16784189

  5. Aerobic and anaerobic metabolism of bovine ciliary process: effects of metabolic and transport inhibitors.

    PubMed

    Braunagel, S C; Yorio, T

    1987-01-01

    In the present study we have measured the oxygen consumption and lactic acid production, under aerobic and anaerobic conditions, in the bovine ciliary process epithelium (CPE) in the presence and absence of transport modifiers. Basal oxygen consumption was 8-15 microliters O2 consumed/mg protein/hr and decreased by 35% when sodium was removed or ouabain was added to the media. Anaerobic metabolism as measured by lactate production was also attenuated by sodium-free or ouabain treatment. When O2 consumption was severely limited by cyanide, lactic acid production increased significantly ("Pasteur effect"), whereas 2-deoxyglucose reduced lactate formation. Both chloride-free and acetazolamide treated CPE increased their dependency on aerobic glycolysis, and this response was also observed under anaerobic conditions, suggesting the presence of an anion transport mechanism. A net lactate production was also found to occur across the aqueous epithelium under aerobic and anaerobic conditions. These results are consistent with the presence of a bicarbonate-sensitive anion transport system located in the ciliary process epithelium.

  6. Effects of anaerobic processing of soybean seeds on the properties of tofu.

    PubMed

    Matsui, Kenji; Takaki, Saki; Shimada, Kazuko; Hajika, Makita

    2011-01-01

    Oxygenation of lipids during the processing soybeans affects the flavor properties of soy products. We prepared tofu under anaerobic conditions and then evaluated its sensory properties and the compositions of volatiles and oxidized lipids. Anaerobic processing resulted in tofu with less intense richness (kokumi) concomitant with reductions in the amounts of oxidized lipids and volatile compounds.

  7. Evaluation of COD effect on anammox process and microbial communities in the anaerobic baffled reactor (ABR).

    PubMed

    Chen, Chongjun; Sun, Faqian; Zhang, Haiqing; Wang, Jianfang; Shen, Yaoliang; Liang, Xinqiang

    2016-09-01

    Nitrogen removal with different organic carbon effect was investigated using anaerobic baffled reactor (ABR) anammox reactor. Results indicated that organic carbon exert an important effect on nitrogen removal through anammox process. When the feeding COD concentration was lower than 99.7mgL(-1), nitrogen removal could be enhanced via the coexistence of denitrification and anammox. Elevated COD could further deteriorate the anammox activity with almost complete inhibition at the COD concentration of 284.1mgL(-1). The nitrogen removal contribution rate of anammox was varied from 92.7% to 6.9%. However, the anammox activity was recovered when the COD/TN was decreased from 2.33 to 1.25 with influent nitrite addition. And, the anammox process was again intensified from 27.0 to 51.2%. High-throughput Miseq sequencing analyses revealed that the predominant phylum changed from Chloroflexi to Proteobacteria with the elevated COD addition, which indicated COD concentration was the most important factor regulating the bacterial community structure.

  8. Evaluation of COD effect on anammox process and microbial communities in the anaerobic baffled reactor (ABR).

    PubMed

    Chen, Chongjun; Sun, Faqian; Zhang, Haiqing; Wang, Jianfang; Shen, Yaoliang; Liang, Xinqiang

    2016-09-01

    Nitrogen removal with different organic carbon effect was investigated using anaerobic baffled reactor (ABR) anammox reactor. Results indicated that organic carbon exert an important effect on nitrogen removal through anammox process. When the feeding COD concentration was lower than 99.7mgL(-1), nitrogen removal could be enhanced via the coexistence of denitrification and anammox. Elevated COD could further deteriorate the anammox activity with almost complete inhibition at the COD concentration of 284.1mgL(-1). The nitrogen removal contribution rate of anammox was varied from 92.7% to 6.9%. However, the anammox activity was recovered when the COD/TN was decreased from 2.33 to 1.25 with influent nitrite addition. And, the anammox process was again intensified from 27.0 to 51.2%. High-throughput Miseq sequencing analyses revealed that the predominant phylum changed from Chloroflexi to Proteobacteria with the elevated COD addition, which indicated COD concentration was the most important factor regulating the bacterial community structure. PMID:27285572

  9. The effect of free nitrous acid on key anaerobic processes in enhanced biological phosphorus removal systems.

    PubMed

    Ye, Liu; Pijuan, Maite; Yuan, Zhiguo

    2013-02-01

    In this study, the effect of nitrite/FNA on the anaerobic metabolism of polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) is investigated. The results clearly show that FNA has a detrimental effect on the acetate uptake rate by both PAOs and GAOs, but this adverse effect is much stronger on PAOs than on GAOs. Also, when FNA was increased, phosphate release to acetate uptake ratio by PAOs increased substantially (250-300% compared to control), which was accompanied by decreases (40-60%) in glycogen degradation and PHA production to VFA uptake. In contrast, these ratios for GAOs remained constant or increased slightly towards the highest FNA concentration applied. These results indicate that the anaerobic metabolism of PAOs is more adversely affected than that of GAOs when FNA is present. This might provide a competitive advantage to GAOs over PAOs in enhanced biological phosphorus removal systems when nitrite is present.

  10. Effects of multiple inhibitory components on anaerobic treatment processes in municipal solid waste incineration leachate.

    PubMed

    Lei, Yuqing; Dang, Yan; Lan, Zhangheng; Sun, Dezhi

    2016-06-01

    This study served to investigate the comparative and combined effects of calcium, ammonia nitrogen, and aquatic humic substances (AHS) on specific methanogenic activity (SMA) in municipal solid waste leachate at mesophilic conditions. Using orthogonal experiments, anaerobic granular sludge was cultured with different concentrations combinations of the three added components for 13 days. The combination of 6000 mg/L calcium, 400 mg/L ammonia nitrogen, and 4000 mg/L AHS was the most inhibitory combination on the SMA of granular sludge, with a calculated 4.49 mL (standard temperature and atmospheric pressure) (STP) CH4/(gVSS·d) of SMA. The SMA with the addition of the inhibitory components was much lower than the control group's (1000 mg/L calcium, 200 mg/L ammonia nitrogen and 2000 mg/L AHS) with a calculated 12.97 mL (STP) CH4/(gVSS·d) of SMA. Calcium was the major inhibitor among the three components followed by AHS. High concentrations of calcium significantly inhibited the utilization of propionate and butyrate in the substrate and further affected the methanogenic process.

  11. Modelling inhibitory effects of long chain fatty acids in the anaerobic digestion process.

    PubMed

    Zonta, Z; Alves, M M; Flotats, X; Palatsi, J

    2013-03-01

    Mathematical modelling of anaerobic digestion process has been used to give new insights regarding dynamics of the long chain fatty acids (LCFA) inhibition. Previously published experimental data, including batch tests with clay mineral bentonite additions, were used for parameter identification. New kinetics were considered to describe the bio-physics of the inhibitory process, including: i) adsorption of LCFA over granular biomass and ii) specific LCFA substrate (saturated/unsaturated) and LCFA-degrading populations. Furthermore, iii) a new variable was introduced to describe the state of damage of the acetoclastic methanogens in order to account for the loss of cell-functionality (inhibition) induced by the adsorbed LCFAs. The proposed model modifications are state compatible and easy to be integrated into the International Water Association's Anaerobic Digestion Model N°1 (ADM1) framework. Practical identifiability of model parameters was assessed with a global sensitivity analysis, while calibration and model structure validation were performed on independent data sets. A reliable simulation of the LCFA-inhibition process can be achieved, if the model includes the description of the adsorptive nature of the LCFAs and the LCFA-damage over specific biomass. The importance of microbial population structure (saturated/unsaturated LCFA-degraders) and the high sensitivity of acetoclastic population to LCFA are evidenced, providing a plausible explanation of experimental based hypothesis. PMID:23276428

  12. Combined thermophilic aerobic process and conventional anaerobic digestion: effect on sludge biodegradation and methane production.

    PubMed

    Dumas, C; Perez, S; Paul, E; Lefebvre, X

    2010-04-01

    The efficiency of hyper-thermophilic (65 degrees Celsius) aerobic process coupled with a mesophilic (35 degrees Celsius) digester was evaluated for the activated sludge degradation and was compared to a conventional mesophilic digester. For two Sludge Retention Time (SRT), 21 and 42 days, the Chemical Oxygen Demand (COD) solubilisation and biodegradation processes, the methanisation yield and the aerobic oxidation were investigated during 180 days. The best results were obtained at SRT of 44 days; the COD removal yield was 30% higher with the Mesophilic Anaerobic Digestion/Thermophilic Aerobic Reactor (MAD-TAR) co-treatment. An increase of the sludge intrinsic biodegradability is also observed (20-40%), showing that the unbiodegradable COD in mesophilic conditions becomes bioavailable. However, the methanisation yield was quite similar for both processes at a same SRT. Finally, such a process enables to divide by two the volume of digester with an equivalent efficiency.

  13. [Effect of natural and hydrothermal synthetic goethite on the release of methane in the anaerobic decomposition process of organic matter].

    PubMed

    Yao, Dun-Fan; Chen, Tian-Hu; Wang, Jin; Zhou, Yue-Fei; Yue, Zheng-Bo

    2013-02-01

    The effects of natural goethite (NGt) and synthetic goethite (SGt) on the release of methane in the anaerobic biochemical system consisted of dissimilatory iron-reducing bacteria (DIRB) and methane-producing bacteria (MPB) were investigated through batch tests with sodium acetate as the carbon source. To explore the effects and mechanisms of both mineral materials on the release of methane in the anaerobic decomposition process of organic matter in the presence of DIRB, the main gas components and total organic carbon (TOC) , total inorganic carbon (TIC), and Fe2+ in the aqueous phase of the experimental process were determined and XRD analyses were conducted for the solid-phase product. Moreover, the minerals were analyzed by specific surface area (BET), X-ray diffraction (XRD), X-ray fluorescence (XRF). Modified Gompertz equation was used to fit the cumulative methane and carbon dioxide. Results showed that the maximum cumulative production of methane was brought forward by 60-78 days by the addition of goethite and CO2 was effectively reduced by 30% - 67% compared with the control samples. SGt was more effective than NGt in promoting the release of CH4 and reducing the CO, emission. Furthermore, the analysis of the solid product showed that the addition of goethite can fix part of CO2 by the formation of siderite.

  14. Processing anaerobic sludge for extended storage as anaerobic digester inoculum.

    PubMed

    Li, Jiajia; Zicari, Steven M; Cui, Zongjun; Zhang, Ruihong

    2014-08-01

    Thermophilic anaerobic sludge was processed to reduce the volume and moisture content in order to reduce costs for storing and transporting the sludge as microbial inoculum for anaerobic digester startup. The moisture content of the sludge was reduced from 98.7% to 82.0% via centrifugation and further to 71.5% via vacuum evaporation. The processed sludge was stored for 2 and 4 months and compared with the fresh sludge for the biogas and methane production using food waste and non-fat dry milk as substrates. It was found that fresh unprocessed sludge had the highest methane yield and the yields of both unprocessed and processed sludges decreased during storage by 1-34%, however processed sludges seemed to regain some activity after 4 months of storage as compared to samples stored for only 2 months. Maximum methane production rates obtained from modified Gompertz model application also increased between the 2-month and 4-month processed samples.

  15. Electron beam/biological processing of anaerobic and aerobic sludge

    NASA Astrophysics Data System (ADS)

    Čuba, V.; Pospíšil, M.; Múčka, V.; Jeníček, P.; Dohányos, M.; Zábranská, J.

    2003-01-01

    Besides common chemical and biological methods, the radiation technology is a promising way of sludge treatment. The paper describes possibilities of combined accelerated electrons/biological processing of both anaerobic and aerobic sludge. Besides one-shot experiments, experimental reactors for the simulation of anaerobic processes have been used. Main effort has been aimed to decrease organic compounds concentration and overall volume of solids, to improve some physico-chemical parameters of sludge, to validate hygienisation effects of the ionising radiation, and in the case of anaerobic sludge, to increase the volume of the produced biogas. Positive effects of the electron beam processing have been observed on all previously named parameters.

  16. Development of a treatment system for molasses wastewater: the effects of cation inhibition on the anaerobic degradation process.

    PubMed

    Onodera, Takashi; Sase, Shinya; Choeisai, Pairaya; Yoochatchaval, Wilasinee; Sumino, Haruhiko; Yamaguchi, Takashi; Ebie, Yoshitaka; Xu, Kaiqin; Tomioka, Noriko; Mizuochi, Motoyuki; Syutsubo, Kazuaki

    2013-03-01

    This study evaluated the process performance of a novel treatment system consisting of an acidification reactor, an upflow staged sludge bed (USSB) reactor, an upflow anaerobic sludge blanket reactor, and an aerobic trickling filter for the treatment of a high-strength molasses wastewater with a chemical oxygen demand (COD) of up to 120,000mg/L. The USSB operating at 35°C was capable of achieving an organic loading rate of 11kgCOD/m(3) day with a methane recovery of 62.4% at an influent COD of 120,000mg/L. The final effluent COD was 4520mg/L. The system was effective with regard to nitrification and sulfur removal. Fifty percent inhibition of the bacterial activity of the retained sludge by the cations was determined at 8gK/L for sucrose degradation, 16gK/L for sulfate reduction, and 12gK/L or 9gNa/L for acetoclastic methane production. Cation inhibition of anaerobic degradation reduced the process performance of the USSB.

  17. Inhibition of anaerobic digestion process: a review.

    PubMed

    Chen, Ye; Cheng, Jay J; Creamer, Kurt S

    2008-07-01

    Anaerobic digestion is an attractive waste treatment practice in which both pollution control and energy recovery can be achieved. Many agricultural and industrial wastes are ideal candidates for anaerobic digestion because they contain high levels of easily biodegradable materials. Problems such as low methane yield and process instability are often encountered in anaerobic digestion, preventing this technique from being widely applied. A wide variety of inhibitory substances are the primary cause of anaerobic digester upset or failure since they are present in substantial concentrations in wastes. Considerable research efforts have been made to identify the mechanism and the controlling factors of inhibition. This review provides a detailed summary of the research conducted on the inhibition of anaerobic processes. The inhibitors commonly present in anaerobic digesters include ammonia, sulfide, light metal ions, heavy metals, and organics. Due to the difference in anaerobic inocula, waste composition, and experimental methods and conditions, literature results on inhibition caused by specific toxicants vary widely. Co-digestion with other waste, adaptation of microorganisms to inhibitory substances, and incorporation of methods to remove or counteract toxicants before anaerobic digestion can significantly improve the waste treatment efficiency.

  18. POLISHING THE EFFLUENT FROM AN ANAEROBIC BIOLOGICAL PERCHLORATE TREATMENT PROCESS

    EPA Science Inventory

    Anaerobic biological processes effectively reduce perchlorate to chloride. However, the effluent can be biologically unstable, high in particulates and high in disinfection by-product precursor compounds. Such an effluent would be unsuitable for transmission into a drinking water...

  19. [Effect of different volume loading of aerobic/anaerobic zone on nitrogen and phosphorus removal by biofilm and granular sludge coupling process].

    PubMed

    Yin, Hang; Liu, Chang; Gao, Hui; Gao, Da-Wen

    2014-05-01

    The effect of different aerobic/anaerobic zone volume loading on nitrogen and phosphorus removal by biological film and granular coupling process was investigated using a self-designed Biofilm/Granular sludge coupling reactor. Three operating modes were conducted in the experiment. In operating mode I ,the volume of aerobic zone was 9. 66 L, and the volume of anaerobic zone was 15. 34 L. In operating mode II , the volume of aerobic zone was 12. 56 L, and the volume of anaerobic zone was 12. 44 L. In operating mode III , the volume of aerobic zone was 15.42 L, and the volume of anaerobic zone was 9.58 L. Three operating modes expressed different volume loading of the reactor because of different aerobic/anaerobic zone. The results showed that the performance of ammonia nitrogen and phosphorus removal was a bit poor in operating mode I , the effluent nitrate nitrogen was higher in operating mode III compared with other modes, which brought the total nitrogen removal efficiency lower. The operating mode II was optimal for nitrogen and phosphorus removal. In operating mode II , the ammonia nitrogen removal efficiency was about 80. 63% , the volume loading rate of nitrogen removal was about 150. 27 g(m3 d)-1, and the COD removal efficiency was higher than 83.24%; the amounts of phosphorus release and uptake under anaerobic conditions were 7. 23 mg L-1 and 11. 93 mg L-1.

  20. Effects of volatile fatty acids on a thermophilic anaerobic hydrogen fermentation process degrading peptone.

    PubMed

    Cheng, S S; Chang, S M; Chen, S T

    2002-01-01

    Hydrogen fermentation using glucose as a single substrate caused abrupt pH drops and the gradual losses of hydrogen producers, which in turn led to system failure. In this study the use of a proteinaceous substrate, peptone, avoided the abrupt pH drops in the reactive system and allowed for further exploration of volatile fatty acids (VFAs) and pH effects on the hydrogen fermentation process. Our results showed that: (1) during the hydrogen fermentation tests, the abrupt pH drops were avoided thus system stability increased due to the production of ammonia from the peptone fermented, (2) pH control was not necessary and the addition of acetate to the process had little effect on the hydrogen fermentation process, (3) at the extreme pHs the addition of acetate either lengthened the lag phase (pH < or = 6) or slowed the hydrogen production rate (pH > or = 8), and both situations were not desired, and (4) high VFA content in the system sped up the consumption of hydrogen gas. Results of this study suggested that the hydrogen fermentation using the protein-containing substances as substrate was beneficial in maintaining the system pH. As long as the pH was maintained around 6-8, system inhibition due to VFAs accumulation was minimized. Thus, the optimal operation of a hydrogen fermentation process would be achievable via the control of substrate composition at a certain carbohydrate-to-protein ratio.

  1. Effects of stabilization and sludge properties in a combined process of anaerobic digestion and thermophilic aerobic digestion.

    PubMed

    Cheng, Jiehong; Kong, Feng; Zhu, Jun; Wu, Xiao

    2015-01-01

    A novel process of combining mesophilic (<35°C) anaerobic digestion with the thermophilic (55°C) aerobic digestion process (AN-TAD) was designed to stabilize sludge and economize aeration energy. Effects of stabilization and sludge properties for AN-TAD process were evaluated by batch experiments during a 25 d digestion period. The sludges digested by AN-TAD process achieved the requirements for Class-A sludge standard. The sludge at total solid (TS) 5.4% had the highest value of decay coefficient K(d(55)) at 0.1851 d(-1) among the three TS contents according to the first-order kinetics equation. Oxidation reduction potential at below 0 mV remained for sludges at TSs of 6.5%, 5.4%, and 4.6% for at least 15 d because of initial hydrolytic-acidification. Concentrations of nitrogen and phosphorus in sludges at TSs of 6.5%, 5.4%, and 4.6% gradually increased up to the highest values in the supernatant during the initial 13 d, causing low utilized value in land application as a fertilizer. Prolonging the retention time for more than 15 d was considered because soluble phosphorus precipitated in the solid phase. High content of soluble organic matters of the soluble chemical oxygen demand, protein, and polysaccharide in the supernatant caused deterioration in sludge dewaterability rates. PMID:25950189

  2. Process configuration role in anaerobic biotransformations

    SciTech Connect

    Speece, R.E.

    1998-07-01

    Defining the environmental conditions which would enable anaerobic processes to consistently produce effluents containing only non-detectable concentrations of degradable organics would remove one of the main drawbacks to wider application of this important treatment technology. Recently specific metabolic intermediates formed in the anaerobic biotransformation of complex organics have been found to enhance or curtail process performance. Using acrylate and acrolein as representative hazardous chemicals, modifications in staging and reactor operation procedures have been observed in the author's laboratory to profoundly impact the rate and completeness of the biotransformation process. Specific metabolic intermediates formed in the biotransformation of complex substrates to a large extent will control a given process performance and process configuration greatly impacts the metabolic pathway, thus impacting the intermediates formed as well. There is a growing body of literature to indicate that process performance in anaerobic biotransformation is greatly impacted by reactor configuration. There is also some evidence that metabolic precursors impact the subsequent efficiency of conversion of volatile fatty acids (VFA) ultimately to CH{sub 4}. But although profound differences in the performance of anaerobic biotransformation are reported for various process configurations, there are no published criteria to guide the rational design of stages/phased processes. Clarification of the relative merits of single stage, two stage, two phase, granules and biofilms as well as CSTR and plug flow modes in the biotransformation of hazardous pollutants would be foundational for future research and development.

  3. Inhibitory Effects of Silver Nanoparticles on Removal of Organic Pollutants and Sulfate in an Anaerobic Biological Wastewater Treatment Process.

    PubMed

    Rasool, Kashif; Lee, Dae Sung

    2016-05-01

    The increasing use of silver nanoparticles (AgNPs) in commercial products and industrial processes raises issues regarding the toxicity of sludge biomass in biological wastewater treatment plants, due to potential antimicrobial properties. This study investigated the effects of AgNPs on removal of organic pollutants and sulfate in an anaerobic biological sulfate reduction process. At AgNPs concentrations of up to 10 mg/L, no significant inhibition of sulfate and COD removal was observed. However, at higher concentrations (50-200 mg/L) sulfate and COD removal efficiencies were significantly decreased to 51.8% and 33.6%, respectively. Sulfate and COD reduction followed first-order kinetics at AgNPs concentrations of up to 10 mg/L and second-order kinetics at AgNPs concentrations of 50-200 mg/L. Lactate dehydrogenase release profiles showed increases in cytotoxicity at AgNPs concentrations greater than 50 mg/L suggesting cell membrane disruption. Analysis of extracellular polymeric substances (EPS) from sulfidogenic sludge biomass and of Fourier transform infrared (FT-IR) spectra showed a decrease in concentrations of carbohydrates, proteins, humic substances, and lipids in the presence of AgNPs. Moreover, the interaction of AgNPs with sludge biomass and the damage caused to cell walls were confirmed through scanning electron microscopy with energy dispersive X-ray spectroscopy. PMID:27483773

  4. Anammox for nitrogen removal from anaerobically pre-treated municipal wastewater: Effect of COD/N ratios on process performance and bacterial community structure.

    PubMed

    Leal, Cíntia Dutra; Pereira, Alyne Duarte; Nunes, Fernando Terra; Ferreira, Luísa Ornelas; Coelho, Aline Carolina Cirilo; Bicalho, Sarah Kinaip; Mac Conell, Erika F Abreu; Ribeiro, Thiago Bressani; de Lemos Chernicharo, Carlos Augusto; de Araújo, Juliana Calábria

    2016-07-01

    Long-term effects of COD/N ratios on the nitrogen removal performance and bacterial community of an anammox reactor were evaluated by adding a synthetic medium (with glucose) and real anaerobic effluent to a SBR. At a COD/N ratio of 2.8 (COD, 390mg·L(-1)) ammonium removal efficiency was 66%, while nitrite removal remained high (99%). However, at a COD/N ratio of 5.0 (COD, 300mg·L(-1)), ammonium and nitrite removal efficiencies were high (84% and 99%, respectively). High COD, nitrite, and ammonium removal efficiencies (80%, 90% and 95%, respectively) were obtained on adding anaerobically pre-treated municipal wastewater (with nitrite) to the reactor. DGGE revealed that the addition of anaerobic effluent changed the bacterial community structure and selected for DNA sequences related to Brocadia sinica and Chloroflexi. Adding glucose and anaerobic effluent increased denitrifiers concentration threefold. Thus, the possibility of using the anammox process to remove nitrogen from anaerobically pre-treated municipal wastewater was demonstrated.

  5. Anammox for nitrogen removal from anaerobically pre-treated municipal wastewater: Effect of COD/N ratios on process performance and bacterial community structure.

    PubMed

    Leal, Cíntia Dutra; Pereira, Alyne Duarte; Nunes, Fernando Terra; Ferreira, Luísa Ornelas; Coelho, Aline Carolina Cirilo; Bicalho, Sarah Kinaip; Mac Conell, Erika F Abreu; Ribeiro, Thiago Bressani; de Lemos Chernicharo, Carlos Augusto; de Araújo, Juliana Calábria

    2016-07-01

    Long-term effects of COD/N ratios on the nitrogen removal performance and bacterial community of an anammox reactor were evaluated by adding a synthetic medium (with glucose) and real anaerobic effluent to a SBR. At a COD/N ratio of 2.8 (COD, 390mg·L(-1)) ammonium removal efficiency was 66%, while nitrite removal remained high (99%). However, at a COD/N ratio of 5.0 (COD, 300mg·L(-1)), ammonium and nitrite removal efficiencies were high (84% and 99%, respectively). High COD, nitrite, and ammonium removal efficiencies (80%, 90% and 95%, respectively) were obtained on adding anaerobically pre-treated municipal wastewater (with nitrite) to the reactor. DGGE revealed that the addition of anaerobic effluent changed the bacterial community structure and selected for DNA sequences related to Brocadia sinica and Chloroflexi. Adding glucose and anaerobic effluent increased denitrifiers concentration threefold. Thus, the possibility of using the anammox process to remove nitrogen from anaerobically pre-treated municipal wastewater was demonstrated. PMID:27023380

  6. Effects of freeze-thaw cycles on anaerobic microbial processes in an Arctic intertidal mud flat.

    PubMed

    Sawicka, Joanna E; Robador, Alberto; Hubert, Casey; Jørgensen, Bo Barker; Brüchert, Volker

    2010-04-01

    Insight into the effects of repeated freezing and thawing on microbial processes in sediments and soils is important for understanding sediment carbon cycling at high latitudes acutely affected by global warming. Microbial responses to repeated freeze-thaw conditions were studied in three complementary experiments using arctic sediment collected from an intertidal flat that is exposed to seasonal freeze-thaw conditions (Ymerbukta, Svalbard, Arctic Ocean). The sediment was subjected to oscillating freeze-thaw incubations, either gradual, from -5 to 4 degrees C, or abrupt, from -20 to 10 degrees C. Concentrations of low-molecular weight carboxylic acids (volatile fatty acids) were measured and sulfate reduction was assessed by measuring (35)S sulfate reduction rates (SRRs). Gradual freeze-thaw incubation decreased microbial activity in the frozen state to 0.25 % of initial levels at 4 degrees C, but activity resumed rapidly reaching >60 % of initial activity in the thawed state. Exposure of sediments to successive large temperature changes (-20 versus 10 degrees C) decreased SRR by 80% of the initial activity, suggesting that a fraction of the bacterial community recovered rapidly from extreme temperature fluctuations. This is supported by 16S rRNA gene-based denaturing gradient gel electrophoresis profiles that revealed persistence of the dominant microbial taxa under repeated freeze-thaw cycles. The fast recovery of the SRRs suggests that carbon mineralization in thawing arctic sediment can resume without delay or substantial growth of microbial populations.

  7. Modelling sodium inhibition on the anaerobic digestion process.

    PubMed

    Hierholtzer, A; Akunna, J C

    2012-01-01

    Sodium is a known process inhibitor in anaerobic systems and impacts on methanogens through an increase of osmotic pressure or complete dehydration of microorganisms. In this study, a combination of experimental and modelling approaches has been employed to determine and simulate sodium inhibition on the anaerobic digestion process. The ADM1, which has been successfully used in modelling anaerobic processes, has been modified to include an extra inhibition function that considers the effect of sodium on acetoclastic methanogens and the impact on biogas production and composition. A non-competitive inhibition function was added to the rate of acetate uptake for the model to take into account sodium toxicity. Experimental studies consisted of both batch and reactor tests to obtain parameters for model calibration and validation. The calibrated model was used to predict the effect of ammonia nitrogen on sodium toxicity. It was found that relatively low sodium levels can bring about significant levels of process inhibition in the presence of high levels of ammonia. On the other hand, where the concentration of ammonia is relatively low, the tolerance threshold for sodium ions increases. Hence, care must be taken in the use of sodium hydroxide for pH adjustment during anaerobic digestion of protein-rich substrates.

  8. Anaerobic Mesophilic Codigestion of Rice Straw and Chicken Manure: Effects of Organic Loading Rate on Process Stability and Performance.

    PubMed

    Mei, Zili; Liu, Xiaofeng; Huang, Xianbo; Li, Dong; Yan, Zhiying; Yuan, Yuexiang; Huang, Yajun

    2016-07-01

    To investigate the effects of organic loading rate (OLR) on performance and stability of mesophilic co-digestion of rice straw (RS) and chicken manure (CM), benchtop experiments (40 L) were carried out at OLRs of 3.0, 3.6, 4.2, 4.8, 6.0, 8.0, and 12.0 kg volatile solid (VS)/(m(3)·day) with volatile solid (VS) ratio of 1:1 (RS/CM) which was based on batch tests. Anaerobic co-digestion was slightly and severely inhibited by the accumulation of ammonia when the digester was overloaded at an OLR of 6 and 12 kg VS/(m(3)·day), respectively. The recommended OLR for co-digestion is 4.8 kg VS/(m(3)·day), which corresponds to average specific biogas production (SBP) of 380 L/kg VS and volumetric biogas production rate (VBPR) of 1.8 m(3)/(m(3)·day). An OLR of 6-8 kg VS/(m(3)·d) with SBP of 360-440 L/kg VS and VBPR of 2.1-3.5 m(3)/(m(3)·day) could be considered, if an Anaerobic digestion (AD) system assisted by in situ removal of ammonia was adopted. PMID:26940572

  9. Anaerobic Digestion. Student Manual. Biological Treatment Process Control.

    ERIC Educational Resources Information Center

    Carnegie, John W., Ed.

    This student manual contains the textual material for a four-lesson unit on anaerobic digestion control. Areas addressed include: (1) anaerobic sludge digestion (considering the nature of raw sludge, purposes of anaerobic digestion, the results of digestion, types of equipment, and other topics); (2) digester process control (considering feeding…

  10. [Sulfa-drug wastewater treatment with anaerobic/aerobic process].

    PubMed

    Wu, L; Zhang, H; Zhu, H; Zhang, Z; Zhuang, Y; Dai, S

    2001-09-01

    Sulfa drug wastewater was treated with anaerobic/aerobic process. The removal ratios of TOC reached about 50% in anaerobic phase and about 70% in aerobic phase respectively, while volume loading rate of TOC was about 1.2 kg/(m3.d) in anaerobic phase and about 0.6 kg/(m3.d) in aerobic phase. Removal of TOC in anaerobic phase was attributed to the reduction of sulfate.

  11. Effect of the Organic Loading Rate Increase and the Presence of Zeolite on Microbial Community Composition and Process Stability During Anaerobic Digestion of Chicken Wastes.

    PubMed

    Ziganshina, Elvira E; Belostotskiy, Dmitry E; Ilinskaya, Olga N; Boulygina, Eugenia A; Grigoryeva, Tatiana V; Ziganshin, Ayrat M

    2015-11-01

    This study investigates the effect of the organic loading rate (OLR) increase from 1.0 to 3.5 g VS L(-1) day(-1) at constant hydraulic retention time (HRT) of 35 days on anaerobic reactors' performance and microbial diversity during mesophilic anaerobic digestion of ammonium-rich chicken wastes in the absence/presence of zeolite. The effects of anaerobic process parameters on microbial community structure and dynamics were evaluated using a 16S ribosomal RNA gene-based pyrosequencing approach. Maximum 12 % of the total ammonia nitrogen (TAN) was efficiently removed by zeolite in the fixed zeolite reactor (day 87). In addition, volatile fatty acids (VFA) in the fixed zeolite reactor accumulated in lower concentrations at high OLR of 3.2-3.5 g VS L(-1) day(-1). Microbial communities in the fixed zeolite reactor and reactor without zeolite were dominated by various members of Bacteroidales and Methanobacterium sp. at moderate TAN and VFA levels. The increase of the OLR accompanied by TAN and VFA accumulation and increase in pH led to the predominance of representatives of the family Erysipelotrichaceae and genera Clostridium and Methanosarcina. Methanosarcina sp. reached relative abundances of 94 and 57 % in the fixed zeolite reactor and reactor without zeolite at the end of the experimental period, respectively. In addition, the diminution of Synergistaceae and Crenarchaeota and increase in the abundance of Acholeplasmataceae in parallel with the increase of TAN, VFA, and pH values were observed.

  12. Pulse power enhancement of the anaerobic digester process

    SciTech Connect

    Greene, H.W.

    1996-12-31

    A pilot study of the effects of Pulse Power Processing on an anaerobic digester system was completed at the Decatur Utilities Dry Creek Wastewater Treatment Plant, in Decatur Alabama, in September, 1995. This patented method generates several significant effects when all biosolids material is treated as it enters the anaerobic system. Intense, high peak-power plasma arcs are created, one at each end of the parabolic processing chamber, to produce an amplified synergy of alterations to the digester sludge flowing between them. The millisecond electric discharges generate localized temperatures as high as 30,000 K{degrees}, followed by a rapid cooling of the flowing liquid, which produces acoustic shock waves with pressures approaching 5,000 atmospheres. This destructive force: ruptures many of the cell walls of the bacteria and other single-cell organisms, releasing their vacuole fluids; breaks carbon bonds to form smaller organic compounds; and pulverizes large particle conglomerates, increasing the overall surface area of the solids. These beneficial results serve to boost the nutrient source for the anaerobes in the digester. In conjunction with LTV radiation, the formation of excited chemical radicals (including OH{sup -}), and the changes in ionic charge through alteration of the zeta potential, the bioreactor system is turbocharged to enhance the conversion of volatile biosolids to methane gas, which is the natural respiratory by-product of anaerobic digestion.

  13. Effects of metal salt addition on odor and process stability during the anaerobic digestion of municipal waste sludge.

    PubMed

    Abbott, Timothy; Eskicioglu, Cigdem

    2015-12-01

    Anaerobic digestion (AD) is an effective way to recover energy and nutrients from organic waste; however, several issues including the solubilization of bound nutrients and the production of corrosive, highly odorous and toxic volatile sulfur compounds (VSCs) in AD biogas can limit its wider adoption. This study explored the effects of adding two different doses of ferric chloride, aluminum sulfate and magnesium hydroxide directly to the feed of complete mix semi-continuously fed mesophilic ADs on eight of the most odorous VSCs in AD biogas at three different organic loading rates (OLR). Ferric chloride was shown to be extremely effective in reducing VSCs by up to 87%, aluminum sulfate had the opposite effect and increased VSC levels by up to 920%, while magnesium hydroxide was not shown to have any significant impact. Ferric chloride, aluminum sulfate and magnesium hydroxide were effective in reducing the concentration of orthophosphate in AD effluent although both levels of alum addition caused digester failure at elevated OLRs. Extensive foaming was observed within the magnesium hydroxide dosed digesters, particularly at higher doses and high OLRs. Certain metal salt additions may be a valuable tool in overcoming barriers to AD and to meet regulatory targets. PMID:26260964

  14. Cellulase production by the anaerobic digestion process

    SciTech Connect

    Khan, A.W.; van den Berg, L.

    1981-01-01

    An anaerobic digestion process is described for the production of cellulolytic enzymes using a methanogenic cellulose-enrichment culture. After a heat treatment designed to destroy all but spore-forming bacteria, this culture produced cellulase from a variety of cellulosic materials as well as from cellobiose. The enzyme system contained endo- and exoglucanase, acted on filter paper, and showed cellobiase and xylanase activities. It was stable at 2/sup 0/C under aerobic conditions and showed a pH optimum at 5 and a temperature optimum at 50/sup 0/C. Endoglucanase and filter paper activities were mostly exogenic, whereas cellobiase and xylanase activities were cell associated. The cellulolytic activity produced by this mixed culture was comparable to that of commercially available fungal preparations, and the process could be useful as an alternate source for these enzymes.

  15. Effect of music on anaerobic exercise performance.

    PubMed

    Atan, T

    2013-03-01

    For years, mostly the effects of music on cardiorespiratory exercise performance have been studied, but a few studies have examined the effect of music on anaerobic exercise. The purpose of this study was to assess the effect of listening to music and its rhythm on anaerobic exercise: on power output, heart rate and the concentration of blood lactate. 28 male subjects were required to visit the laboratory on 6 occasions, each separated by 48 hours. Firstly, each subject performed the Running-based Anaerobic Sprint Test (RAST) under 3 conditions on separate days: while listening to "slow rhythm music", "fast rhythm music" or "no music". 48 hours after the subjects completed RAST under 3 conditions, Wingate Anaerobic Power (WAN) tests were performed under 3 music conditions. The order of the 3 conditions (slow music, fast music and no music) was selected randomly to prevent an order effect. Results showed no significant differences between 3 conditions in anaerobic power assessments, heart rate or blood lactate (p > 0.05). On the basis of these results it can be said that music cannot improve anaerobic performance. The type of music had no impact on power outputs during RAST and WAN exercise. As a conclusion, listening to music and its rhythm cannot enhance anaerobic performance and cannot change the physiological response to supramaximal exercise. PMID:24744463

  16. A novel application of an anaerobic membrane process in wastewater treatment.

    PubMed

    You, H S; Tseng, C C; Peng, M J; Chang, S H; Chen, Y C; Peng, S H

    2005-01-01

    The applications of membrane processes in anaerobic biological wastewater treatment still have some limitations due to severe membrane scaling and fouling, although they have been proven to achieve superior COD removal and biomass retention. An innovative anaerobic membrane process for wastewater treatment was conducted to control the membrane scaling problems. The process comprises an anaerobic reactor, an aerobic reactor, and a membrane separation tank. Anaerobic sludge from a full-scale UASB reactor treating food wastewater was inoculated to anaerobic and aerobic reactor to purify synthetic wastewater consisting of glucose and sodium acetate. The anaerobic reactor was operated in a sludge bed type without three-phase separator. The aerobic reactor can eliminate residual organics from the anaerobic reactor effluent using facultative microorganisms. To provide solid-liquid separation, hollow fiber ultrafiltration module was submerged in the separation tank. The results clearly show that the anaerobic membrane process combined methanogenic and aerobic COD reduction is a stable system. No fatal scaling was found after two months of operation even without chemical cleaning for the membrane. It was also found that inorganic precipitates formed in the aerobic reactor were reduced due to CO2 stripping in aerobic reactor. Another important finding was that the inorganic precipitates were entrapped into facultative aerobes floc. The ash/SS ratio of aerobes floc increased from 0.17 to 0.55 after 50 days of operation, which confirms this phenomenon. Based on our investigation, the new process can control scaling effectively to extend the membrane application in anaerobic treatment.

  17. The Pasteur effect in facultative anaerobic metazoa.

    PubMed

    Schmidt, H; Kamp, G

    1996-05-15

    The existence and the regulatory mechanisms of the Pasteur effect in facultative anaerobic metazoa are discussed. There are three reasons for the controversy surrounding this phenomenon. 1) The different definitions of the Pasteur effect, 2) the antagonistic effect of metabolic depression and its species specific response to hypoxia, as well as 3) the laboratory-specific differences in the experimental procedures for analyzing the Pasteur effect and its regulation. This review aims to clarify the confusion about the existence of the Pasteur effect in facultative anaerobic metazoa and to offer possible molecular mechanisms.

  18. POLISHING THE EFFLUENT FROM AN ANAEROBIC BIOLOGICAL PERCHLORATE TREATMENT PROCESS - SLIDES

    EPA Science Inventory

    Anaerobic biological processes effectively reduce perchlorate to chloride. However, the effluent can be biologically unstable, high in particulates and high in disinfection by-product precursor compounds. Such an effluent would be unsuitable for transmission into a drinking water...

  19. Effect of different pH-values on process parameters in two-phase anaerobic digestion of high-solid substrates.

    PubMed

    Lindner, Jonas; Zielonka, Simon; Oechsner, Hans; Lemmer, Andreas

    2015-01-01

    In many publications, primary fermentation is described as a limiting step in the anaerobic digestion of fibre-rich biomass [Eastman JA, Ferguson JF. Solubilization of particulacte carbon during the anaerobic digeston. J WPCF. 1981;53:352-366; Noike T, Endo G, Chang J, Yaguchi J, Matsumoto J. Characteristics of carbohydrate degradation and the rate-limiting step in anaerobic digestion. Biotechnol Bioeng. 1985;27:1482-1489; Arntz HJ, Stoppok E, Buchholz K. Anaerobic hydroysis of beet pulp-discontiniuous experiments. Biotechnol Lett. 1985;7:113-118]. The microorganisms of the primary fermentation process differ widely from the methanogenic microorganisms [Pohland FG, Ghosh S. Developments in anaerobic stabilization of organic wastes-the two-phase concept. Environ Lett. 1971;1:255-266]. To optimize the biogas process, a separation in two phases is suggested by many authors [Fox P, Pohland GK. Anaerobic treatment applications and fundamentals: substrate specificity during phase separation. Water Environ Res. 1994;66:716-724; Cohen A, Zoetemeyer RJ, van Deursen A, van Andel JG. Anaerobic digestion of glucose with separated acid production and methane formation. Water Res. 1979;13:571-580]. To carry out the examination, a two-phase laboratory-scale biogas plant was established, with a physical phase separation. In previous studies, the regulation of the pH-value during the acid formation was usually carried out by the addition of sodium hydroxide [Cohen A, Zoetemeyer RJ, van Deursen A, van Andel JG. Anaerobic digestion of glucose with separated acid production and methane formation. Water Res. 1979;13:571-580; Ueno Y, Tatara M, Fukui H, Makiuchi T, Goto M, Sode K. Production of hydrogen and methane from organic solid wastes by phase separation of anaerobic process. Bioresour Technol. 2007;98:1861-1865; Zoetemeyer RJ, van den Heuvel JC, Cohen A. pH influence on acidogenic dissimilation of glucose in an anaerobic digestor. Water Res. 1982;16:303-311]. A new technology

  20. Effect of different pH-values on process parameters in two-phase anaerobic digestion of high-solid substrates.

    PubMed

    Lindner, Jonas; Zielonka, Simon; Oechsner, Hans; Lemmer, Andreas

    2015-01-01

    In many publications, primary fermentation is described as a limiting step in the anaerobic digestion of fibre-rich biomass [Eastman JA, Ferguson JF. Solubilization of particulacte carbon during the anaerobic digeston. J WPCF. 1981;53:352-366; Noike T, Endo G, Chang J, Yaguchi J, Matsumoto J. Characteristics of carbohydrate degradation and the rate-limiting step in anaerobic digestion. Biotechnol Bioeng. 1985;27:1482-1489; Arntz HJ, Stoppok E, Buchholz K. Anaerobic hydroysis of beet pulp-discontiniuous experiments. Biotechnol Lett. 1985;7:113-118]. The microorganisms of the primary fermentation process differ widely from the methanogenic microorganisms [Pohland FG, Ghosh S. Developments in anaerobic stabilization of organic wastes-the two-phase concept. Environ Lett. 1971;1:255-266]. To optimize the biogas process, a separation in two phases is suggested by many authors [Fox P, Pohland GK. Anaerobic treatment applications and fundamentals: substrate specificity during phase separation. Water Environ Res. 1994;66:716-724; Cohen A, Zoetemeyer RJ, van Deursen A, van Andel JG. Anaerobic digestion of glucose with separated acid production and methane formation. Water Res. 1979;13:571-580]. To carry out the examination, a two-phase laboratory-scale biogas plant was established, with a physical phase separation. In previous studies, the regulation of the pH-value during the acid formation was usually carried out by the addition of sodium hydroxide [Cohen A, Zoetemeyer RJ, van Deursen A, van Andel JG. Anaerobic digestion of glucose with separated acid production and methane formation. Water Res. 1979;13:571-580; Ueno Y, Tatara M, Fukui H, Makiuchi T, Goto M, Sode K. Production of hydrogen and methane from organic solid wastes by phase separation of anaerobic process. Bioresour Technol. 2007;98:1861-1865; Zoetemeyer RJ, van den Heuvel JC, Cohen A. pH influence on acidogenic dissimilation of glucose in an anaerobic digestor. Water Res. 1982;16:303-311]. A new technology

  1. Characteristics, Process Parameters, and Inner Components of Anaerobic Bioreactors

    PubMed Central

    Abdelgadir, Awad; Chen, Xiaoguang; Liu, Jianshe; Xie, Xuehui; Zhang, Jian; Zhang, Kai; Wang, Heng; Liu, Na

    2014-01-01

    The anaerobic bioreactor applies the principles of biotechnology and microbiology, and nowadays it has been used widely in the wastewater treatment plants due to their high efficiency, low energy use, and green energy generation. Advantages and disadvantages of anaerobic process were shown, and three main characteristics of anaerobic bioreactor (AB), namely, inhomogeneous system, time instability, and space instability were also discussed in this work. For high efficiency of wastewater treatment, the process parameters of anaerobic digestion, such as temperature, pH, Hydraulic retention time (HRT), Organic Loading Rate (OLR), and sludge retention time (SRT) were introduced to take into account the optimum conditions for living, growth, and multiplication of bacteria. The inner components, which can improve SRT, and even enhance mass transfer, were also explained and have been divided into transverse inner components, longitudinal inner components, and biofilm-packing material. At last, the newly developed special inner components were discussed and found more efficient and productive. PMID:24672798

  2. Anaerobic oxidation of methane: progress with an unknown process.

    PubMed

    Knittel, Katrin; Boetius, Antje

    2009-01-01

    Methane is the most abundant hydrocarbon in the atmosphere, and it is an important greenhouse gas, which has so far contributed an estimated 20% of postindustrial global warming. A great deal of biogeochemical research has focused on the causes and effects of the variation in global fluxes of methane throughout earth's history, but the underlying microbial processes and their key agents remain poorly understood. This is a disturbing knowledge gap because 85% of the annual global methane production and about 60% of its consumption are based on microbial processes. Only three key functional groups of microorganisms of limited diversity regulate the fluxes of methane on earth, namely the aerobic methanotrophic bacteria, the methanogenic archaea, and their close relatives, the anaerobic methanotrophic archaea (ANME). The ANME represent special lines of descent within the Euryarchaeota and appear to gain energy exclusively from the anaerobic oxidation of methane (AOM), with sulfate as the final electron acceptor according to the net reaction: CH(4) + SO(42-) ---> HCO(3-) + HS(-) + H(2)O. This review summarizes what is known and unknown about AOM on earth and its key catalysts, the ANME clades and their bacterial partners.

  3. Cost-effectiveness analysis of TOC removal from slaughterhouse wastewater using combined anaerobic-aerobic and UV/H2O2 processes.

    PubMed

    Bustillo-Lecompte, Ciro Fernando; Mehrvar, Mehrab; Quiñones-Bolaños, Edgar

    2014-02-15

    The objective of this study is to evaluate the operating costs of treating slaughterhouse wastewater (SWW) using combined biological and advanced oxidation processes (AOPs). This study compares the performance and the treatment capability of an anaerobic baffled reactor (ABR), an aerated completely mixed activated sludge reactor (AS), and a UV/H2O2 process, as well as their combination for the removal of the total organic carbon (TOC). Overall efficiencies are found to be up to 75.22, 89.47, 94.53, 96.10, 96.36, and 99.98% for the UV/H2O2, ABR, AS, combined AS-ABR, combined ABR-AS, and combined ABR-AS-UV/H2O2 processes, respectively. Due to the consumption of electrical energy and reagents, operating costs are calculated at optimal conditions of each process. A cost-effectiveness analysis (CEA) is performed at optimal conditions for the SWW treatment by optimizing the total electricity cost, H2O2 consumption, and hydraulic retention time (HRT). The combined ABR-AS-UV/H2O2 processes have an optimal TOC removal of 92.46% at an HRT of 41 h, a cost of $1.25/kg of TOC removed, and $11.60/m(3) of treated SWW. This process reaches a maximum TOC removal of 99% in 76.5 h with an estimated cost of $2.19/kg TOC removal and $21.65/m(3) treated SWW, equivalent to $6.79/m(3) day.

  4. Cost-effectiveness analysis of TOC removal from slaughterhouse wastewater using combined anaerobic-aerobic and UV/H2O2 processes.

    PubMed

    Bustillo-Lecompte, Ciro Fernando; Mehrvar, Mehrab; Quiñones-Bolaños, Edgar

    2014-02-15

    The objective of this study is to evaluate the operating costs of treating slaughterhouse wastewater (SWW) using combined biological and advanced oxidation processes (AOPs). This study compares the performance and the treatment capability of an anaerobic baffled reactor (ABR), an aerated completely mixed activated sludge reactor (AS), and a UV/H2O2 process, as well as their combination for the removal of the total organic carbon (TOC). Overall efficiencies are found to be up to 75.22, 89.47, 94.53, 96.10, 96.36, and 99.98% for the UV/H2O2, ABR, AS, combined AS-ABR, combined ABR-AS, and combined ABR-AS-UV/H2O2 processes, respectively. Due to the consumption of electrical energy and reagents, operating costs are calculated at optimal conditions of each process. A cost-effectiveness analysis (CEA) is performed at optimal conditions for the SWW treatment by optimizing the total electricity cost, H2O2 consumption, and hydraulic retention time (HRT). The combined ABR-AS-UV/H2O2 processes have an optimal TOC removal of 92.46% at an HRT of 41 h, a cost of $1.25/kg of TOC removed, and $11.60/m(3) of treated SWW. This process reaches a maximum TOC removal of 99% in 76.5 h with an estimated cost of $2.19/kg TOC removal and $21.65/m(3) treated SWW, equivalent to $6.79/m(3) day. PMID:24486468

  5. Effects of oxidation reduction potential in the bypass micro-aerobic sludge zone on sludge reduction for a modified oxic-settling-anaerobic process.

    PubMed

    Li, Kexun; Wang, Yi; Zhang, Zhongpin; Liu, Dongfang

    2014-01-01

    Batch experiments were conducted to determine the effect of oxidation reduction potential (ORP) on sludge reduction in a bypass micro-aerobic sludge reduction system. The system was composed of a modified oxic-settling-anaerobic process with a sludge holding tank in the sludge recycle loop. The ORPs in the micro-aerobic tanks were set at approximately +350, -90, -150, -200 and -250 mV, by varying the length of aeration time for the tanks. The results show that lower ORP result in greater sludge volume reduction, and the sludge production was reduced by 60% at the lowest ORP. In addition, low ORP caused extracellular polymer substances dissociation and slightly reduced sludge activity. Comparing the sludge backflow characteristics of the micro-aerobic tank's ORP controlled at -250 mV with that of +350 mV, the average soluble chemical oxygen (SCOD), TN and TP increased by 7, 0.4 and 2 times, median particle diameter decreased by 8.5 μm and the specific oxygen uptake rate (SOUR) decreased by 0.0043 milligram O2 per gram suspended solids per minute. For the effluent, SCOD and TN and TP fluctuated around 30, 8.7 and 0.66 mg/L, respectively. Therefore, the effective assignment of ORP in the micro-aerobic tank can remarkably reduce sludge volume and does not affect final effluent quality.

  6. Effects of trace element addition on process stability during anaerobic co-digestion of OFMSW and slaughterhouse waste.

    PubMed

    Moestedt, J; Nordell, E; Shakeri Yekta, S; Lundgren, J; Martí, M; Sundberg, C; Ejlertsson, J; Svensson, B H; Björn, A

    2016-01-01

    This study used semi-continuous laboratory scale biogas reactors to simulate the effects of trace-element addition in different combinations, while degrading the organic fraction of municipal solid waste and slaughterhouse waste. The results show that the combined addition of Fe, Co and Ni was superior to the addition of only Fe, Fe and Co or Fe and Ni. However, the addition of only Fe resulted in a more stable process than the combined addition of Fe and Co, perhaps indicating a too efficient acidogenesis and/or homoacetogenesis in relation to a Ni-deprived methanogenic population. The results were observed in terms of higher biogas production (+9%), biogas production rates (+35%) and reduced VFA concentration for combined addition compared to only Fe and Ni. The higher stability was supported by observations of differences in viscosity, intraday VFA- and biogas kinetics as well as by the 16S rRNA gene and 16S rRNA of the methanogens.

  7. Effective ethanol production by reutilizing waste distillage anaerobic digestion effluent in an integrated fermentation process coupled with both ethanol and methane fermentations.

    PubMed

    Zhang, Cheng Ming; Mao, Zhong Gui; Wang, Xin; Zhang, Jian Hua; Sun, Fu Bao; Tang, Lei; Zhang, Hong Jian

    2010-11-01

    An integrated ethanol-methane fermentation coupled system characterized with full wastewater reutilization was proposed. The waste distillage originated from ethanol distillation was treated with anaerobic digestion and then recycled for medium preparation in the next ethanol fermentation run. This process could enhance wastewater reutilization, save fresh water and reduce energy consumption in the cassava-based ethanol production. The results indicated that, when using anaerobic effluents from the digestion process with only one tank, an ethanol concentration of 10.5% (v/v) compatible with that of conventional one could be achieved, but ethanol fermentation was partially inhibited and operation time gradually prolonged from 48 to 105 h. Using anaerobic effluents from the digestion process with two subsequently connected tanks, ethanol fermentation performance could be largely improved, and the fermentation lag could be completely eliminated. The performance enhancement was due to the concentrations reduction in organic acids, such as acetic and propionic acids in the digestion effluents using two digestion tanks in-series.

  8. Carbon balance of anaerobic granulation process: carbon credit.

    PubMed

    Wong, Biing-Teo; Show, K Y; Lee, D J; Lai, J Y

    2009-03-01

    The concept of carbon credit arose out of increasing awareness of the need to reduce emissions of greenhouse gases to combat global warming which was formalized in the Kyoto protocol. In addition to contribution to sustainable development with energy recovery in the form of methane, carbon credits can be claimed by application of advanced anaerobic processes in wastewater treatment for reducing emissions of greenhouse gases. As anaerobic granular systems are capable of handling high organic loadings concomitant with high strength wastewater and short hydraulic retention time, they could render much more carbon credits than other conventional anaerobic systems. This study investigated the potential carbon credit derived from laboratory-scale upflow anaerobic sludge blanket (UASB) reactors based on a carbon balance analysis. Methane emission reduction could be calculated by calculating the difference of UASB reactors and open lagoon treatment systems. Based on the 2.5l bench-scale reactor, the total CH(4) emissions reduction was calculated as 29 kg CO(2)/year. On scaling up to a typical full-scale anaerobic digester, the total CH(4) emissions reduction could achieve 46,420 tons CO(2) reduction/year. The estimated carbon credits would amount to 278,500 US$ per year by assuming a carbon price of 6 US$ per metric ton CO(2) reduction. The analysis postulated that it is financially viable to invest in advanced anaerobic granular treatment system from the revenue generated from carbon credits.

  9. Anaerobic oxidation of methane: an "active" microbial process.

    PubMed

    Cui, Mengmeng; Ma, Anzhou; Qi, Hongyan; Zhuang, Xuliang; Zhuang, Guoqiang

    2015-02-01

    The anaerobic oxidation of methane (AOM) is an important sink of methane that plays a significant role in global warming. AOM was first found to be coupled with sulfate reduction and mediated by anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB). ANME, often forming consortia with SRB, are phylogenetically related to methanogenic archaea. ANME-1 is even able to produce methane. Subsequently, it has been found that AOM can also be coupled with denitrification. The known microbes responsible for this process are Candidatus Methylomirabilis oxyfera (M. oxyfera) and Candidatus Methanoperedens nitroreducens (M. nitroreducens). Candidatus Methylomirabilis oxyfera belongs to the NC10 bacteria, can catalyze nitrite reduction through an "intra-aerobic" pathway, and may catalyze AOM through an aerobic methane oxidation pathway. However, M. nitroreducens, which is affiliated with ANME-2d archaea, may be able to catalyze AOM through the reverse methanogenesis pathway. Moreover, manganese (Mn(4+) ) and iron (Fe(3+) ) can also be used as electron acceptors of AOM. This review summarizes the mechanisms and associated microbes of AOM. It also discusses recent progress in some unclear key issues about AOM, including ANME-1 in hypersaline environments, the effect of oxygen on M. oxyfera, and the relationship of M. nitroreducens with ANME. PMID:25530008

  10. Anaerobic oxidation of methane: an “active” microbial process

    PubMed Central

    Cui, Mengmeng; Ma, Anzhou; Qi, Hongyan; Zhuang, Xuliang; Zhuang, Guoqiang

    2015-01-01

    The anaerobic oxidation of methane (AOM) is an important sink of methane that plays a significant role in global warming. AOM was first found to be coupled with sulfate reduction and mediated by anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB). ANME, often forming consortia with SRB, are phylogenetically related to methanogenic archaea. ANME-1 is even able to produce methane. Subsequently, it has been found that AOM can also be coupled with denitrification. The known microbes responsible for this process are Candidatus Methylomirabilis oxyfera (M. oxyfera) and Candidatus Methanoperedens nitroreducens (M. nitroreducens). Candidatus Methylomirabilis oxyfera belongs to the NC10 bacteria, can catalyze nitrite reduction through an “intra-aerobic” pathway, and may catalyze AOM through an aerobic methane oxidation pathway. However, M. nitroreducens, which is affiliated with ANME-2d archaea, may be able to catalyze AOM through the reverse methanogenesis pathway. Moreover, manganese (Mn4+) and iron (Fe3+) can also be used as electron acceptors of AOM. This review summarizes the mechanisms and associated microbes of AOM. It also discusses recent progress in some unclear key issues about AOM, including ANME-1 in hypersaline environments, the effect of oxygen on M. oxyfera, and the relationship of M. nitroreducens with ANME. PMID:25530008

  11. Simultaneous C and N removal from saline salmon effluents in filter reactors comprising anoxic-anaerobic-aerobic processes: effect of recycle ratio.

    PubMed

    Giustinianovich, Elisa A; Aspé, Estrella R; Huiliñir, César E; Roeckel, Marlene D

    2014-01-01

    Salmon processing generates saline effluents with high protein load. To treat these effluents, three compact tubular filter reactors were installed and an integrated anoxic/anaerobic/aerobic process was developed with recycling flow from the reactor's exit to the inlet stream in order to save organic matter (OM) for denitrification. The reactors were aerated in the upper section with recycle ratios (RR) of 0, 2, and 10, respectively, at 30°C. A tubular reactor behave as a plug flow reactor when RR = 0, and as a mixed flow reactor when recycle increases, thus, different RR values were used to evaluate how it affects the product distribution and the global performance. Diluted salmon process effluent was prepared as substrate. Using loads of 1.0 kg COD m(-3)d(-1) and 0.15 kg total Kjeldahl nitrogen (TKN) m(-3)d(-1) at HRT of 2 d, 100% removal efficiencies for nitrite and nitrate were achieved in the anoxic-denitrifying section without effect of the dissolved oxygen in the recycled flow on denitrification. Removals >98% for total organic carbon (TOC) was achieved in the three reactors. The RR had no effect on the TOC removal; nevertheless a higher efficiency in total nitrogen removal in the reactor with the highest recycle ratio was observed: 94.3% for RR = 10 and 46.6% for RR = 2. Results showed that the proposed layout with an alternative distribution in a compact reactor can efficiently treat high organic carbon and nitrogen concentrations from a saline fish effluent with OM savings in denitrification.

  12. The effect of acidic pH and presence of metals as parameters in establishing a sulfidogenic process in anaerobic reactor.

    PubMed

    Vieira, Bárbara F; Couto, Pâmela T; Sancinetti, Giselle P; Klein, Bernhard; van Zyl, Dirk; Rodriguez, Renata P

    2016-08-23

    The successful use of anaerobic reactors for bioremediation of acid mine drainage has been shown in systems with neutral pH. However, the choice of an efficient and suitable process for such wastewater must consider the capability of operating at acidic pH and in the presence of metals. This work studies the performance of an anaerobic batch reactor, under conditions of varying initial pH for its efficiencies in sulfate removal and metal precipitation from synthetic acid mine drainage. The chemical oxygen demand/sulfate (COD/SO4(2-)) ratio used was 1.00, with ethanol chosen as the only energy and carbon source. The initial pH of the synthetic drainage was progressively set from 7.0 to 4.0 to make it as close as possible to that of real acid mine drainage. Metals were also added starting with iron, zinc, and finally copper. The effectiveness of sulfate and COD removal from the synthetic acid mine drainage increased as the initial pH was reduced. The sulfate removal increased from 38.5 ± 3.7% to 52.2 ± 3%, while the removal of organic matter started at 91.7 ± 2.4% and ended at 99 ± 1%. These results indicate that the sulfate reducing bacteria (SRB) community adapted to lower pH values. The metal removal observed was 88 ± 7% for iron, 98.0 ± 0.5% for zinc and 99 ± 1% for copper. At this stage, an increase in the sulfate removal was observed, which reaches up to 82.2 ± 5.8%. The kinetic parameters for sulfate removal were 0.22 ± 0.04 h(-1) with Fe, 0.26 ± 0.04 h(-1) with Fe and Zn and 0.44 ± 0.04 h(-1) with Fe, Zn, and Cu. PMID:27222283

  13. A novel process for anaerobic composting of municipal solid waste

    SciTech Connect

    Chynoweth, D.P.; Bosch, G.; Earle, J.F.K.

    1991-12-31

    A novel process has been developed and evaluated in a pilot-scale program for conversion of the biodegradable fraction of municipal solid waste (MSW) to methane via anaerobic composting. The sequential batch anaerobic composting (SEBAC) process employs leachate management to provide organisms, moisture, and nutrients required for rapid conversion of MSW and removal of inhibitory fermentation products during start-up. The biodegradable organic materials are converted to methane and carbon dioxide in 21-42 d, rather than the years required in landfills.

  14. Biochemical reaction engineering and process development in anaerobic wastewater treatment.

    PubMed

    Aivasidis, Alexander; Diamantis, Vasileios

    2005-01-01

    Developments in production technology have frequently resulted in the concentrated local accumulation of highly organic-laden wastewaters. Anaerobic wastewater treatment, in industrial applications, constitutes an advanced method of synthesis by which inexpensive substrates are converted into valuable disproportionate products. A critical discussion of certain fundamental principles of biochemical reaction engineering relevant to the anaerobic mode of operation is made here, with special emphasis on the roles of thermodynamics, kinetics, mass and heat transfer, reactor design, biomass retention and recycling. The applications of the anaerobic processes are discussed, introducing the principles of an upflow anaerobic sludge bed reactor and a fixed-bed loop reactor. The merits of staging reactor systems are presented using selected examples based on two decades of research in the field of anaerobic fermentation and wastewater treatment at the Forschungszentrum Julich (Julich Research Center, Germany). Wastewater treatment is an industrial process associated with one of the largest levels of mass throughput known, and for this reason it provides a major impetus to further developments in bioprocess technology in general.

  15. The effect of anaerobic fermentation processing of cattle waste for biogas as a renewable energy resources on the number of contaminant microorganism

    NASA Astrophysics Data System (ADS)

    Kurnani, Tb. Benito A.; Hidayati, Yuli Astuti; Marlina, Eulis Tanti; Harlia, Ellin

    2016-02-01

    Beef cattle waste has a positive potential that can be exploited, as well as a negative potential that must be controlled so as not to pollute the environment. Beef cattle waste can be processed into an alternative energy, namely biogas. Anaerobic treatment of livestock waste to produce gas can be a solution in providing optional energy, while the resulted sludge as the fermentation residue can be used as organic fertilizer for crops. However, this sludge may containt patogenic microorganism that will damage human and environmet healt. Therefor, this study was aimed to know the potency of beef cattle waste to produce biogas and the decrease of the microorganism's number by using fixed dome digester. Beef cattle waste was processed into biogas using fixed dome digester with a capacity of 12 m3. Biogas composition was measured using Gas Cromatografi, will microorganism species was identified using Total plate Count Methode. The result of this study shows that the produced biogas contains of 75.77% Mol (CH4), 13.28% Mol (N), and 6.96% Mol (CO2). Furthermor, this study show that the anaerobic fermrntation process is capable of reducing microorganisms that could potentially pollute the environment. The number of Escherichia coli and Samonella sp. were <30 MPN/ml respectively save for environment. This process can reduce 84.70% the amount of molds. The only molds still existed after fermentation was A.fumigatus. The number of protozoa can be reduced in order of 94.73%. Protozoa that can be identified in cattle waste before, and after anaerobic fermentation was merely Eimeria sp.. The process also reduced the yeast of 86.11%. The remaining yeast after fermentation was Candida sp. Finally, about 93.7% of endoparasites was reduced by this process. In this case, every trematode and cestoda were 100% reduced, while the nematode only 75%. Reducing some microorganisms that have the potential to pollute the environment signifies sludge anaerobic fermentation residue is safe to

  16. Atmospheric vs. anaerobic processing of metabolome samples for the metabolite profiling of a strict anaerobic bacterium, Clostridium acetobutylicum.

    PubMed

    Lee, Sang-Hyun; Kim, Sooah; Kwon, Min-A; Jung, Young Hoon; Shin, Yong-An; Kim, Kyoung Heon

    2014-12-01

    Well-established metabolome sample preparation is a prerequisite for reliable metabolomic data. For metabolome sampling of a Gram-positive strict anaerobe, Clostridium acetobutylicum, fast filtration and metabolite extraction with acetonitrile/methanol/water (2:2:1, v/v) at -20°C under anaerobic conditions has been commonly used. This anaerobic metabolite processing method is laborious and time-consuming since it is conducted in an anaerobic chamber. Also, there have not been any systematic method evaluation and development of metabolome sample preparation for strict anaerobes and Gram-positive bacteria. In this study, metabolome sampling and extraction methods were rigorously evaluated and optimized for C. acetobutylicum by using gas chromatography/time-of-flight mass spectrometry-based metabolomics, in which a total of 116 metabolites were identified. When comparing the atmospheric (i.e., in air) and anaerobic (i.e., in an anaerobic chamber) processing of metabolome sample preparation, there was no significant difference in the quality and quantity of the metabolomic data. For metabolite extraction, pure methanol at -20°C was a better solvent than acetonitrile/methanol/water (2:2:1, v/v/v) at -20°C that is frequently used for C. acetobutylicum, and metabolite profiles were significantly different depending on extraction solvents. This is the first evaluation of metabolite sample preparation under aerobic processing conditions for an anaerobe. This method could be applied conveniently, efficiently, and reliably to metabolome analysis for strict anaerobes in air.

  17. Anaerobic Metabolism: Linkages to Trace Gases and Aerobic Processes

    NASA Astrophysics Data System (ADS)

    Megonigal, J. P.; Hines, M. E.; Visscher, P. T.

    2003-12-01

    's surface area, they have a profound influence on the biogeochemistry of the planet. This is evident from the observation that the O2 and CH4 content of Earth's atmosphere are in extreme disequilibrium (Sagan et al., 1993). The combination of high aerobic primary production and anoxic sediments provided the large deposits of fossil fuels that have become vital and contentious sources of energy for modern industrialized societies. Anaerobic metabolism is responsible for the abundance of N2 in the atmosphere; otherwise N2-fixing bacteria would have consumed most of the N2 pool long ago (Schlesinger, 1997). Anaerobic microorganisms are common symbionts of termites, cattle, and many other animals, where they aid digestion. Nutrient and pollutant chemistry are strongly modified by the reduced conditions that prevail in wetland and aquatic ecosystems.This review of anaerobic metabolism emphasizes aerobic oxidation, because the two processes cannot be separated in a complete treatment of the topic. It is process oriented and highlights the fascinating microorganisms that mediate anaerobic biogeochemistry. We begin this review with a brief discussion of CO2 assimilation by autotrophs, the source of most of the reducing power on Earth, and then consider the biological processes that harness this potential energy. Energy liberation begins with the decomposition of organic macromolecules to relatively simple compounds, which are simplified further by fermentation. Methanogenesis is considered next because CH4 is a product of acetate fermentation, and thus completes the catabolism of organic matter, particularly in the absence of inorganic electron acceptors. Finally, the organisms that use nitrogen, manganese, iron, and sulfur for terminal electron acceptors are considered in order of decreasing free-energy yield of the reactions.

  18. Treatment of low strength domestic wastewater by using upflow anaerobic sludge blanket process

    SciTech Connect

    Tang, N.H.; Torres, C.L.; Speece, R.E.

    1996-11-01

    The tropical environment of Puerto Rico offers great potential for using anaerobic treatment in place of conventional, aerobic activated sludge processes in the treatment of its warm, dilute municipal wastewaters. It will minimize the troublesome problem of land disposal of municipal sludges, achieve secondary effluent standards and not be an energy intensive form of treatment. When the infrastructure of sewage treatment needs to be improved, anaerobic sewage treatment may serve as one of the better alternatives. Anaerobic sewage treatment is a totally enclosed process. It has very little environmental impact on the surrounding areas of the treatment site. However, sometimes its effluent may cause serious odor problems. There are many small communities in Puerto Rico where the anaerobic process can be an ideal form of treatment for their sewage. This study is focused on using the upflow anaerobic sludge blanket (UASB) process for treating raw domestic sewage. The objectives of this study were to evaluate the performance and stability of the UASB process for treating raw sewage and to ascertain the effect on efficiency of hydraulic detention time of the UASB reactor. A further key objective was to evaluate the impact on process performance of a packed bed solids removals device following the UASB reactor.

  19. A bio-hybrid anaerobic treatment of papaya processing wastes

    SciTech Connect

    Yang, P.Y.; Chou, C.Y.

    1987-01-01

    Hybrid anaerobic treatment of papaya processing wastes is technically feasible. At 30/sup 0/C, the optimal organic loading rates for maximizing organic removal efficiency and methane production are 1.3 and 4.8 g TCOD/1/day, respectively. Elimination of post-handling and treatment of digested effluent can also be achieved. The system is more suitable for those processing plants with a waste amount of more than 3,000 metric tons per year.

  20. A robust and cost-effective integrated process for nitrogen and bio-refractory organics removal from landfill leachate via short-cut nitrification, anaerobic ammonium oxidation in tandem with electrochemical oxidation.

    PubMed

    Wu, Li-Na; Liang, Da-Wei; Xu, Ying-Ying; Liu, Ting; Peng, Yong-Zhen; Zhang, Jie

    2016-07-01

    A cost-effective process, consisting of a denitrifying upflow anaerobic sludge blanket (UASB), an oxygen-limited anoxic/aerobic (A/O) process for short-cut nitrification, and an anaerobic reactor (ANR) for anaerobic ammonia oxidation (anammox), followed by an electrochemical oxidation process with a Ti-based SnO2-Sb2O5 anode, was developed to remove organics and nitrogen in a sewage diluted leachate. The final chemical oxygen demand (COD), ammonia nitrogen (NH4(+)-N) and total nitrogen (TN) of 70, 11.3 and 39 (all in mg/L), respectively, were obtained. TN removal in UASB, A/O and ANR were 24.6%, 49.6% and 16.1%, respectively. According to the water quality and molecular biology analysis, a high degree of anammox besides short-cut nitrification and denitrification occurred in A/O. Counting for 16.1% of TN removal in ANR, at least 43.2-49% of TN was removed via anammox. The anammox bacteria in A/O and ANR, were in respective titers of (2.5-5.9)×10(9) and 2.01×10(10)copy numbers/(gSS).

  1. A robust and cost-effective integrated process for nitrogen and bio-refractory organics removal from landfill leachate via short-cut nitrification, anaerobic ammonium oxidation in tandem with electrochemical oxidation.

    PubMed

    Wu, Li-Na; Liang, Da-Wei; Xu, Ying-Ying; Liu, Ting; Peng, Yong-Zhen; Zhang, Jie

    2016-07-01

    A cost-effective process, consisting of a denitrifying upflow anaerobic sludge blanket (UASB), an oxygen-limited anoxic/aerobic (A/O) process for short-cut nitrification, and an anaerobic reactor (ANR) for anaerobic ammonia oxidation (anammox), followed by an electrochemical oxidation process with a Ti-based SnO2-Sb2O5 anode, was developed to remove organics and nitrogen in a sewage diluted leachate. The final chemical oxygen demand (COD), ammonia nitrogen (NH4(+)-N) and total nitrogen (TN) of 70, 11.3 and 39 (all in mg/L), respectively, were obtained. TN removal in UASB, A/O and ANR were 24.6%, 49.6% and 16.1%, respectively. According to the water quality and molecular biology analysis, a high degree of anammox besides short-cut nitrification and denitrification occurred in A/O. Counting for 16.1% of TN removal in ANR, at least 43.2-49% of TN was removed via anammox. The anammox bacteria in A/O and ANR, were in respective titers of (2.5-5.9)×10(9) and 2.01×10(10)copy numbers/(gSS). PMID:27115616

  2. Dynamic simulator for anaerobic digestion processes.

    PubMed

    Kleinstreuer, C; Poweigha, T

    1982-09-01

    A transient, two-culture model simulating methane production from biomass has been developed. The simulator, based partially on the work by Andrews and McCarty, is capable of calculating the hydrolysis products of several common organic materials, accommodating various substrate feeding modes, and simulating the transient physico-biochemical transport and conversion processes occurring in the biological, liquid, and gaseous phases of a well-mixed reactor. The mathematical representation of this bioconversion system consists of a set of 11 coupled, nonlinear first-order rate equations based on the principles of mass conservation and biochemical reaction kinetics. The model can be used in conjunction with laboratory investigations and as a simulator for evaluating process control strategies and cost developments.

  3. Improved ADM1 model for anaerobic digestion process considering physico-chemical reactions.

    PubMed

    Zhang, Yang; Piccard, Sarah; Zhou, Wen

    2015-11-01

    The "Anaerobic Digestion Model No. 1" (ADM1) was modified in the study by improving the bio-chemical framework and integrating a more detailed physico-chemical framework. Inorganic carbon and nitrogen balance terms were introduced to resolve the discrepancies in the original bio-chemical framework between the carbon and nitrogen contents in the degraders and substrates. More inorganic components and solids precipitation processes were included in the physico-chemical framework of ADM1. The modified ADM1 was validated with the experimental data and used to investigate the effects of calcium ions, magnesium ions, inorganic phosphorus and inorganic nitrogen on anaerobic digestion in batch reactor. It was found that the entire anaerobic digestion process might exist an optimal initial concentration of inorganic nitrogen for methane gas production in the presence of calcium ions, magnesium ions and inorganic phosphorus. PMID:26253912

  4. Improved ADM1 model for anaerobic digestion process considering physico-chemical reactions.

    PubMed

    Zhang, Yang; Piccard, Sarah; Zhou, Wen

    2015-11-01

    The "Anaerobic Digestion Model No. 1" (ADM1) was modified in the study by improving the bio-chemical framework and integrating a more detailed physico-chemical framework. Inorganic carbon and nitrogen balance terms were introduced to resolve the discrepancies in the original bio-chemical framework between the carbon and nitrogen contents in the degraders and substrates. More inorganic components and solids precipitation processes were included in the physico-chemical framework of ADM1. The modified ADM1 was validated with the experimental data and used to investigate the effects of calcium ions, magnesium ions, inorganic phosphorus and inorganic nitrogen on anaerobic digestion in batch reactor. It was found that the entire anaerobic digestion process might exist an optimal initial concentration of inorganic nitrogen for methane gas production in the presence of calcium ions, magnesium ions and inorganic phosphorus.

  5. Effect of ultrasonication on anaerobic degradability of solid waste digestate.

    PubMed

    Boni, M R; D'Amato, E; Polettini, A; Pomi, R; Rossi, A

    2016-02-01

    This paper evaluates the effect of ultrasonication on anaerobic biodegradability of lignocellulosic residues. While ultrasonication has been commonly applied as a pre-treatment of the feed substrate, in the present study a non-conventional process configuration based on recirculation of sonicated digestate to the biological reactor was evaluated at the lab-scale. Sonication tests were carried out at different applied energies ranging between 500 and 50,000kJ/kg TS. Batch anaerobic digestion tests were performed on samples prepared by mixing sonicated and untreated substrate at two different ratios (25:75 and 75:25 w/w). The results showed that when applied as a post-treatment of digestate, ultrasonication can positively affect the yield of anaerobic digestion, mainly due to the dissolution effect of complex organic molecules that have not been hydrolyzed by biological degradation. A good correlation was found between the CH4 production yield and the amount of soluble organic matter at the start of digestion tests. The maximum gain in biogas production was 30% compared to that attained with the unsonicated substrate, which was tentatively related to the type and concentration of the metabolic products.

  6. Influent Fractionation for Modeling Continuous Anaerobic Digestion Processes.

    PubMed

    Lübken, Manfred; Kosse, Pascal; Koch, Konrad; Gehring, Tito; Wichern, Marc

    2015-01-01

    The first dynamic model developed to describe anaerobic digestion processes dates back to 1969. Since then, considerable improvements in identifying the underlying biochemical processes and associated microorganisms have been achieved. These have led to an increasing complexity of both model structure and the standard set of stoichiometric and kinetic parameters. Literature has always paid attention to kinetic parameter estimation, as this determines model accuracy with respect to predicting the dynamic behavior of biogas systems. As sufficient computing power is easily available nowadays, sophisticated linear and nonlinear parameter estimation techniques are applied to evaluate parameter uncertainty. However, the uncertainty of influent fractionation in these parameter optimization procedures is generally neglected. As anaerobic digestion systems are currently increasingly used to convert a broad variety of organic biomass to methane, the lack of generally accepted guidelines for input characterization adapted to the simulation model's characteristics is a considerable limitation of model application to these substrates. Directly after the introduction of the standardized Anaerobic Digestion Model No. 1 (ADM1), several publications pointed out that the model's requirement of a detailed influent characterization can hardly be fulfilled. The main shortcoming of the model application was addressed in the reliable and practical identification of the model's input state variables for particulate and soluble carbohydrates, proteins and lipids, as well as for the inerts. Several authors derived biomass characterization procedures, most of them dedicated to a particular substrate, and some of them being of general nature, but none of these approaches have resulted in a practical standard protocol so far. This review provides an overview of existing approaches that improve substrate influent characterization to be used for state of the art anaerobic digestion models. PMID

  7. Low temperature thermo-chemical pretreatment of dairy waste activated sludge for anaerobic digestion process.

    PubMed

    Rani, R Uma; Kumar, S Adish; Kaliappan, S; Yeom, Ick-Tae; Banu, J Rajesh

    2012-01-01

    An investigation into the influence of low temperature thermo-chemical pretreatment on sludge reduction in a semi-continuous anaerobic reactor was performed. Firstly, effect of sludge pretreatment was evaluated by COD solubilization, suspended solids reduction and biogas production. At optimized condition (60 °C with pH 12), COD solubilization, suspended solids, reduction and biogas production was 23%, 22% and 51% higher than the control, respectively. Secondly, semi-continuous process performance was studied in a lab-scale semi-continuous anaerobic reactor (5 L), with 4 L working volume. With three operated SRTs, the SRT of 15 days was found to be most appropriate for economic operation of the reactor. Combining pretreatment with anaerobic digestion led to 80.5%, 117% and 90.4% of TS, SS and VS reduction respectively, with an improvement of 103% in biogas production. Thus, low temperature thermo-chemical can play an important role in reducing sludge production.

  8. Process performance of anaerobic co-digestion of raw and acidified pig slurry.

    PubMed

    Moset, V; Cerisuelo, A; Sutaryo, S; Møller, H B

    2012-10-15

    The effect of incorporating different ratios of acidified pig slurry on methane yield was evaluated in two scales of anaerobic digesters: Thermophilic (50 °C) pilot scale digester (120 l), operating with an average hydraulic retention time of 20 days and thermophilic (52 °C) full-scale digesters (10 and 30 m(3)), operating with an average hydraulic retention time of 30 days. In the lab-scale digester, different inclusion levels of acidified slurry (0-60%) were tested each 15 days, to determine the maximum ratio of acidified to non-acidified slurry causing inhibition and to find process state indicators helping to prevent process failure. In the full-scale digesters, the level of inclusion of the acidified slurry was chosen from the ratio causing methane inhibition in the pilot scale experiment and was carried on in a long-term process of 100 days. The optimal inclusion level of acidified pig slurry in anaerobic co-digestion with conventional slurry was 10%, which promoted anaerobic methane yield by nearly 20%. Higher inclusion levels caused methane inhibition and volatile fatty acids accumulations in both experiments. In order to prevent process failure, the most important traits to monitor in the anaerobic digestion of acidified pig slurry were found to be: sulfate content of the slurry, alkalinity parameters (especially partial alkalinity and the ratio of alkalinity) and total volatile fatty acids (especially acetic and butyric acids).

  9. An assessment of ocean margin anaerobic processes on oceanic alkalinity budget

    NASA Astrophysics Data System (ADS)

    Hu, Xinping; Cai, Wei-Jun

    2011-09-01

    Recent interest in the ocean's capacity to absorb atmospheric CO2 and buffer the accompanying "ocean acidification" has prompted discussions on the magnitude of ocean margin alkalinity production via anaerobic processes. However, available estimates are largely based on gross reaction rates or misconceptions regarding reaction stoichiometry. In this paper, we argue that net alkalinity gain does not result from the internal cycling of nitrogen and sulfur species or from the reduction of metal oxides. Instead, only the processes that involve permanent loss of anaerobic remineralization products, i.e., nitrogen gas from net denitrification and reduced sulfur (i.e., pyrite burial) from net sulfate reduction, could contribute to this anaerobic alkalinity production. Our revised estimate of net alkalinity production from anaerobic processes is on the order of 4-5 Tmol yr-1 in global ocean margins that include both continental shelves and oxygen minimum zones, significantly smaller than the previously estimated rate of 16-31 Tmol yr-1. In addition, pyrite burial in coastal habitats (salt marshes, mangroves, and seagrass meadows) may contribute another 0.1-1.1 Tmol yr-1, although their long-term effect is not yet clear under current changing climate conditions and rising sea levels. Finally, we propose that these alkalinity production reactions can be viewed as "charge transfer" processes, in which negative charges of nitrate and sulfate ions are converted to those of bicarbonate along with a net loss of these oxidative anions.

  10. An assessment of continental shelf anaerobic processes on oceanic alkalinity budget

    NASA Astrophysics Data System (ADS)

    Hu, X.; Cai, W.

    2010-12-01

    Recent interest in the ocean’s capacity to absorb atmospheric CO2 and buffer the accompanying “ocean acidification” has prompted discussion on the magnitude of continental shelf alkalinity production via anaerobic processes (denitrification, sulfate and redox metal reduction). Recent studies have suggested that atmospheric CO2 could be sequestered along with these reactions. Unfortunately, available estimates are largely based on gross reaction rates or misconceptions regarding reaction stoichiometry. In fact, net alkalinity gain does not result from the internal cycling of nitrogen and sulfur species, or from the reduction of metal oxides. Instead, only the processes that involve permanent loss of anaerobic remineralization products, i.e., nitrogen gas from net denitrification and reduced sulfur (i.e., pyrite burial) from net sulfate reduction, could contribute to this anaerobic alkalinity production. Our revised estimate of net alkalinity production from anaerobic processes is on the order of 4-5 Tmol yr-1 in global continental shelf areas, significantly smaller than the previously estimated rates. In addition, pyrite burial in coastal habitats (salt marshes, mangroves, and seagrass meadows) may contribute another 0.1-1.1 Tmol yr-1 alkalinity although their long-term effect is not yet clear under current changing climate conditions and rising sea levels. Finally, we propose that these alkalinity production reactions can be viewed as “charge transfer” processes, in which negative charges of nitrate and sulfate ions are converted to those of bicarbonate along with a net loss of these oxidative anions.

  11. Automatic process control in anaerobic digestion technology: A critical review.

    PubMed

    Nguyen, Duc; Gadhamshetty, Venkataramana; Nitayavardhana, Saoharit; Khanal, Samir Kumar

    2015-10-01

    Anaerobic digestion (AD) is a mature technology that relies upon a synergistic effort of a diverse group of microbial communities for metabolizing diverse organic substrates. However, AD is highly sensitive to process disturbances, and thus it is advantageous to use online monitoring and process control techniques to efficiently operate AD process. A range of electrochemical, chromatographic and spectroscopic devices can be deployed for on-line monitoring and control of the AD process. While complexity of the control strategy ranges from a feedback control to advanced control systems, there are some debates on implementation of advanced instrumentations or advanced control strategies. Centralized AD plants could be the answer for the applications of progressive automatic control field. This article provides a critical overview of the available automatic control technologies that can be implemented in AD processes at different scales.

  12. The effects of operational and environmental variations on anaerobic wastewater treatment systems: a review.

    PubMed

    Leitão, Renato Carrhá; van Haandel, Adrianus Cornelius; Zeeman, Grietje; Lettinga, Gatze

    2006-06-01

    With the aim of improving knowledge about the stability and reliability of anaerobic wastewater treatment systems, several researchers have studied the effects of operational or environmental variations on the performance of such reactors. In general, anaerobic reactors are affected by changes in external factors, but the severity of the effect is dependent upon the type, magnitude, duration and frequency of the imposed changes. The typical responses include a decrease in performance, accumulation of volatile fatty acids, drop in pH and alkalinity, change in biogas production and composition, and sludge washout. This review summarises the causes, types and effects of operational and environmental variation on anaerobic wastewater treatment systems. However, there still remain some unclear technical and scientific aspects that are necessary for the improvement of the stability and reliability of anaerobic processes.

  13. Citrus essential oils and their influence on the anaerobic digestion process: an overview.

    PubMed

    Ruiz, B; Flotats, X

    2014-11-01

    Citrus waste accounts for more than half of the whole fruit when processed for juice extraction. Among valorisation possibilities, anaerobic digestion for methane generation appears to be the most technically feasible and environmentally friendly alternative. However, citrus essential oils can inhibit this biological process. In this paper, the characteristics of citrus essential oils, as well as the mechanisms of their antimicrobial effects and potential adaptation mechanisms are reviewed. Previous studies of anaerobic digestion of citrus waste under different conditions are presented; however, some controversy exists regarding the limiting dosage of limonene for a stable process (24-192 mg of citrus essential oil per liter of digester and day). Successful strategies to avoid process inhibition by citrus essential oils are based either on recovery or removal of the limonene, by extraction or fungal pre-treatment respectively. PMID:25081855

  14. Citrus essential oils and their influence on the anaerobic digestion process: an overview.

    PubMed

    Ruiz, B; Flotats, X

    2014-11-01

    Citrus waste accounts for more than half of the whole fruit when processed for juice extraction. Among valorisation possibilities, anaerobic digestion for methane generation appears to be the most technically feasible and environmentally friendly alternative. However, citrus essential oils can inhibit this biological process. In this paper, the characteristics of citrus essential oils, as well as the mechanisms of their antimicrobial effects and potential adaptation mechanisms are reviewed. Previous studies of anaerobic digestion of citrus waste under different conditions are presented; however, some controversy exists regarding the limiting dosage of limonene for a stable process (24-192 mg of citrus essential oil per liter of digester and day). Successful strategies to avoid process inhibition by citrus essential oils are based either on recovery or removal of the limonene, by extraction or fungal pre-treatment respectively.

  15. Anaerobic digestion and co-digestion processes of vegetable and fruit residues: process and microbial ecology.

    PubMed

    Garcia-Peña, E I; Parameswaran, P; Kang, D W; Canul-Chan, M; Krajmalnik-Brown, R

    2011-10-01

    This study evaluated the feasibility of methane production from fruit and vegetable waste (FVW) obtained from the central food distribution market in Mexico City using an anaerobic digestion (AD) process. Batch systems showed that pH control and nitrogen addition had significant effects on biogas production, methane yield, and volatile solids (VS) removal from the FVW (0.42 m(biogas)(3)/kg VS, 50%, and 80%, respectively). Co-digestion of the FVW with meat residues (MR) enhanced the process performance and was also evaluated in a 30 L AD system. When the system reached stable operation, its methane yield was 0.25 (m(3)/kg TS), and the removal of the organic matter measured as the total chemical demand (tCOD) was 65%. The microbial population (general Bacteria and Archaea) in the 30 L system was also determined and characterized and was closely correlated with its potential function in the AD system.

  16. Optimization of process parameters for production of volatile fatty acid, biohydrogen and methane from anaerobic digestion.

    PubMed

    Khan, M A; Ngo, H H; Guo, W S; Liu, Y; Nghiem, L D; Hai, F I; Deng, L J; Wang, J; Wu, Y

    2016-11-01

    The anaerobic digestion process has been primarily utilized for methane containing biogas production over the past few years. However, the digestion process could also be optimized for producing volatile fatty acids (VFAs) and biohydrogen. This is the first review article that combines the optimization approaches for all three possible products from the anaerobic digestion. In this review study, the types and configurations of the bioreactor are discussed for each type of product. This is followed by a review on optimization of common process parameters (e.g. temperature, pH, retention time and organic loading rate) separately for the production of VFA, biohydrogen and methane. This review also includes additional parameters, treatment methods or special additives that wield a significant and positive effect on production rate and these products' yield.

  17. Optimization of process parameters for production of volatile fatty acid, biohydrogen and methane from anaerobic digestion.

    PubMed

    Khan, M A; Ngo, H H; Guo, W S; Liu, Y; Nghiem, L D; Hai, F I; Deng, L J; Wang, J; Wu, Y

    2016-11-01

    The anaerobic digestion process has been primarily utilized for methane containing biogas production over the past few years. However, the digestion process could also be optimized for producing volatile fatty acids (VFAs) and biohydrogen. This is the first review article that combines the optimization approaches for all three possible products from the anaerobic digestion. In this review study, the types and configurations of the bioreactor are discussed for each type of product. This is followed by a review on optimization of common process parameters (e.g. temperature, pH, retention time and organic loading rate) separately for the production of VFA, biohydrogen and methane. This review also includes additional parameters, treatment methods or special additives that wield a significant and positive effect on production rate and these products' yield. PMID:27570139

  18. Bench-scale Analysis of Surrogates for Anaerobic Digestion Processes.

    PubMed

    Carroll, Zachary S; Long, Sharon C

    2016-05-01

    Frequent monitoring of anaerobic digestion processes for pathogen destruction is both cost and time prohibitive. The use of surrogates to supplement regulatory monitoring may be one solution. To evaluate surrogates, a semi-batch bench-scale anaerobic digester design was tested. Bench-scale reactors were operated under mesophilic (36 °C) and thermophilic (53-55 °C) conditions, with a 15 day solids retention time. Biosolids from different facilities and during different seasons were examined. USEPA regulated pathogens and surrogate organisms were enumerated at different times throughout each experiment. The surrogate organisms included fecal coliforms, E. coli, enterococci, male-specific and somatic coliphages, Clostridium perfringens, and bacterial spores. Male-specific coliphages tested well as a potential surrogate organism for virus inactivation. None of the tested surrogate organisms correlated well with helminth inactivation under the conditions studied. There were statistically significant differences in the inactivation rates between the facilities in this study, but not between seasons. PMID:27131309

  19. Treatment of artificial soybean wastewater anaerobic effluent in a continuous aerobic-anaerobic coupled (CAAC) process with excess sludge reduction.

    PubMed

    Wang, Jun; Li, Xiaoxia; Fu, Weichao; Wu, Shihan; Li, Chun

    2012-12-01

    In this study, treatment of artificial soybean wastewater anaerobic effluent was studied in a continuous aerobic-anaerobic coupled (CAAC) process. The focus was on COD and nitrogen removal as well as excess sludge reduction. During the continuous operation without reflux, the COD removal efficiency was 96.5% at the optimal hydraulic retention time (HRT) 1.3 days. When HRT was shortened to 1.0 day, reflux from anaerobic zone to moving bed biofilm reactor (MBBR) was introduced. The removal efficiencies of COD and TN were 94.4% and 76.0% at the optimal reflux ratio 30%, respectively. The sludge yield coefficient of CAAC was 0.1738, the simultaneous removal of COD and nitrogen with in situ sludge reduction could be achieved in this CAAC process. The sludge reduction mechanism was discussed by soluble components variation along the water flow. PMID:23073101

  20. Simulation of constituent processes of anaerobic degradation of organic matter by the "methane" model.

    PubMed

    Vavilin, V A; Vasiliev, V B; Rytov, S V

    1996-01-01

    The model of anaerobic digestion described earlier by the authors was used for analysis of the different phases of the process. It was shown that at the glucose conversion a coexistence of hydrogen-producing acidogenic bacteria and hydrogen-utilizing non-methanogenic bacteria causes a hydrogen partial pressure decrease at an increase of solids retention time (i), the intensity of the negative feed-back effect in sulfate-reduction through hydrogen sulfide formation is regulated by the pH level during an oscillation dynamics in acetate/sulfate system (ii), under the toxicity influence the processes of methanogenesis and acetogenesis together with hydrolysis may be rate-limiting steps in the anaerobic system with particulate substrate degradation (iii). PMID:8678475

  1. Impact of agricultural activities on anaerobic processes in stream sediments

    NASA Astrophysics Data System (ADS)

    Schade, J. D.; Ludwig, S.; Nelson, L. C.; Porterfield, J.; Sather, K. L.; Songpitak, M.; Spawn, S.; Weigel, B.

    2013-12-01

    Streams draining agriculture watersheds are subject to significant anthropogenic impacts, including sedimentation from soil erosion and high nitrate input from heavy fertilizer application. Sedimentation degrades habitat and can reduce hydrologic exchange between surface and subsurface waters. Disconnecting surface and subsurface flow reduces oxygen input to hyporheic water, increasing the extent of anoxic zones in stream sediments and creating hotspots for anaerobic processes like denitrification and methanogenesis that can be important sources of nitrous oxide and methane, both powerful greenhouse gases. Increased nitrate input may influence greenhouse gas fluxes from stream sediments by stimulating rates of denitrification and potentially reducing rates of methanogenesis, either through direct inhibition or by increasing competition for organic substrates from denitrifying bacteria. We hypothesized that accumulation of fine sediments in stream channels would result in high rates of methanogenesis in stream sediments, and that increased nitrate input from agricultural runoff would stimulate denitrification and reduce rates of methane production. Our work focused on streams in northern and central Minnesota, in particular on Rice Creek, a small stream draining an agricultural watershed. We used a variety of approaches to test our hypotheses, including surveys of methane concentrations in surface waters of streams ranging in sediment type and nitrate concentration, bottle incubations of sediment from several sites in Rice Creek, and the use of functional gene probes and RNA analyses to determine if genes for these processes are present and being expressed in stream sediments. We found higher methane concentrations in surface water from streams with large deposits of fine sediments, but significantly less methane in these streams when nitrate concentrations were high. We also found high potential for both methanogenesis and denitrification in sediment incubations

  2. Phenols in anaerobic digestion processes and inhibition of ammonia oxidising bacteria (AOB) in soil.

    PubMed

    Levén, Lotta; Nyberg, Karin; Korkea-Aho, Lena; Schnürer, Anna

    2006-07-01

    This study focuses on the presence of phenols in digestate from seven Swedish large-scale anaerobic digestion processes and their impact on the activity of ammonia oxidising bacteria (AOB) in soil. In addition, the importance of feedstock composition and phenol degradation capacity for the occurrence of phenols in the digestate was investigated in the same processes. The results revealed that the content of phenols in the digestate was related to the inhibition of the activity of AOB in soil (EC(50)=26 microg phenols g(-1) d.w. soil). In addition, five pure phenols (phenol, o-, p-, m-cresol and 4-ethylphenol) inhibited the AOB to a similar extent (EC(50)=43-110 microg g(-1) d.w. soil). The phenol content in the digestate was mainly dependent on the composition of the feedstock, but also to some extent by the degradation capacity in the anaerobic digestion process. Swine manure in the feedstock resulted in digestate containing higher amounts of phenols than digestate from reactors with less or no swine manure in the feedstock. The degradation capacity of phenol and p-cresol was studied in diluted small-scale batch cultures and revealed that anaerobic digestion at mesophilic temperatures generally exhibited a higher degradation capacity compared to digestion at thermophilic temperature. Although phenol, p-cresol and 4-ethylphenol were quickly degraded in soil, the phenols added with the digestate constitute an environmental risk according to the guideline values for contaminated soils set by the Swedish Environmental Protection Agency. In conclusion, the management of anaerobic digestion processes is of decisive importance for the production of digestate with low amounts of phenols, and thereby little risks for negative effects of the phenols on the soil ecosystem.

  3. A modified oxic-settling-anaerobic activated sludge process using gravity thickening for excess sludge reduction

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Li, Shi-Yu; Jiang, Feng; Wu, Ke; Liu, Guang-Li; Lu, Hui; Chen, Guang-Hao

    2015-09-01

    Oxic-settling-anaerobic process (OSA) was known as a cost-effective way to reduce the excess sludge production with simple upgrade of conventional activated sludge process (CAS). A low oxidation-reduction potential (ORP) level was the key factor to sludge decay and lysis in the sludge holding tank of the OSA process. However, the ORP control with nitrogen purge or chemical dosing in the OSA process would induce extra expense and complicate the operation. Hence, in this study, a sludge holding tank using gravity thickening was applied to OSA process to reduce the excess sludge production without any ORP control. Results showed that the modified OSA process not only reduced the excess sludge production effectively but also improved the sludge settleability without affected the treatment capacity. The reduction of the excess sludge production in the modified OSA process resulted from interactions among lots of factors. The key element of the process was the gravity thickening sludge holding tank.

  4. A modified oxic-settling-anaerobic activated sludge process using gravity thickening for excess sludge reduction

    PubMed Central

    Wang, Jun; Li, Shi-Yu; Jiang, Feng; Wu, Ke; Liu, Guang-Li; Lu, Hui; Chen, Guang-Hao

    2015-01-01

    Oxic-settling-anaerobic process (OSA) was known as a cost-effective way to reduce the excess sludge production with simple upgrade of conventional activated sludge process (CAS). A low oxidation-reduction potential (ORP) level was the key factor to sludge decay and lysis in the sludge holding tank of the OSA process. However, the ORP control with nitrogen purge or chemical dosing in the OSA process would induce extra expense and complicate the operation. Hence, in this study, a sludge holding tank using gravity thickening was applied to OSA process to reduce the excess sludge production without any ORP control. Results showed that the modified OSA process not only reduced the excess sludge production effectively but also improved the sludge settleability without affected the treatment capacity. The reduction of the excess sludge production in the modified OSA process resulted from interactions among lots of factors. The key element of the process was the gravity thickening sludge holding tank. PMID:26350761

  5. Early warning indicators for monitoring the process failure of anaerobic digestion system of food waste.

    PubMed

    Li, Lei; He, Qingming; Wei, Yunmei; He, Qin; Peng, Xuya

    2014-11-01

    To determine reliable state parameters which could be used as early warning indicators of process failure due to the acidification of anaerobic digestion of food waste, three mesophilic anaerobic digesters of food waste with different operation conditions were investigated. Such parameters as gas production, methane content, pH, concentrations of volatile fatty acid (VFA), alkalinity and their combined indicators were evaluated. Results revealed that operation conditions significantly affect the responses of parameters and thus the optimal early warning indicators of each reactor differ from each other. None of the single indicators was universally valid for all the systems. The universally valid indicators should combine several parameters to supply complementary information. A combination of total VFA, the ratio of VFA to total alkalinity (VFA/TA) and the ratio of bicarbonate alkalinity to total alkalinity (BA/TA) can reflect the metabolism of the digesting system and realize rapid and effective early warning.

  6. Effect of respiratory warm-up on anaerobic power.

    PubMed

    Özdal, Mustafa; Bostanci, Özgür; Dağlioğlu, Önder; Ağaoğlu, Seydi Ahmet; Kabadayi, Menderes

    2016-07-01

    [Purpose] The aim of the present study was to examine the effects of respiratory muscle warm-up on anaerobic power. [Subjects and Methods] Thirty male field hockey players (age, 20.5 ± 2.0 years) each participated in a control (CAN) trial and an experimental (EAN) trial. The EAN trial involved respiratory muscle warm-up, while the CAN trial did not. Anaerobic power was measured using the Wingate protocol. Paired sample t-tests were used to compare the EAN and CAN trials. [Results] There were significant increases in peak power and relative peak power, and decreases in the time to peak after the EAN trial by 8.9%, 9.6%, and 28.8% respectively. [Conclusion] Respiratory muscle warm-up may positively affect anaerobic power due to faster attainment of peak power. PMID:27512273

  7. Effect of respiratory warm-up on anaerobic power

    PubMed Central

    Özdal, Mustafa; Bostanci, Özgür; Dağlioğlu, Önder; Ağaoğlu, Seydi Ahmet; Kabadayi, Menderes

    2016-01-01

    [Purpose] The aim of the present study was to examine the effects of respiratory muscle warm-up on anaerobic power. [Subjects and Methods] Thirty male field hockey players (age, 20.5 ± 2.0 years) each participated in a control (CAN) trial and an experimental (EAN) trial. The EAN trial involved respiratory muscle warm-up, while the CAN trial did not. Anaerobic power was measured using the Wingate protocol. Paired sample t-tests were used to compare the EAN and CAN trials. [Results] There were significant increases in peak power and relative peak power, and decreases in the time to peak after the EAN trial by 8.9%, 9.6%, and 28.8% respectively. [Conclusion] Respiratory muscle warm-up may positively affect anaerobic power due to faster attainment of peak power. PMID:27512273

  8. In-Situ Anaerobic Biosurfactant Production Process For Remediation Of DNAPL Contamination In Subsurface Aquifers

    NASA Astrophysics Data System (ADS)

    Albino, J. D.; Nambi, I. M.

    2009-12-01

    Microbial Enhanced Oil Recovery (MEOR) and remediation of aquifers contaminated with hydrophobic contaminants require insitu production of biosurfactants for mobilization of entrapped hydrophobic liquids. Most of the biosurfactant producing microorganisms produce them under aerobic condition and hence surfactant production is limited in subsurface condition due to lack of oxygen. Currently bioremediation involves expensive air sparging or excavation followed by exsitu biodegradation. Use of microorganisms which can produce biosurfactants under anaerobic conditions can cost effectively expedite the process of insitu bioremediation or mobilization. In this work, the feasibility of anaerobic biosurfactant production in three mixed anaerobic cultures prepared from groundwater and soil contaminated with chlorinated compounds and municipal sewage sludge was investigated. The cultures were previously enriched under complete anaerobic conditions in the presence of Tetrachloroethylene (PCE) for more than a year before they were studied for biosurfactant production. Biosurfactant production under anaerobic conditions was simulated using two methods: i) induction of starvation in the microbial cultures and ii) addition of complex fermentable substrates. Positive result for biosurfactant production was not observed when the cultures were induced with starvation by adding PCE as blobs which served as the only terminal electron acceptor. However, slight reduction in interfacial tension was noticed which was caused by the adherence of microbes to water-PCE interface. Biosurfactant production was observed in all the three cultures when they were fed with complex fermentable substrates and surface tension of the liquid medium was lowered below 35 mN/m. Among the fermentable substrates tested, vegetable oil yielded highest amount of biosurfactant in all the cultures. Complete biodegradation of PCE to ethylene at a faster rate was also observed when vegetable oil was amended to the

  9. Supplementation of ammonium bicarbonates for the treatment of fruit cordial wastewater by anaerobic digestion process.

    PubMed

    Redzwan, Ghufran; Banks, Charles J

    2010-02-01

    Lack of nitrogenous substrate and buffering capacity have been identified as causing failure in previous work on the treatment of fruit cordial wastewater using anaerobic continuous stirred tank reactors. In this study, ammonium bicarbonate was proposed to be used as the substrate for nitrogenous and buffering resources. In order to determine the toxicity effect of the ammonium salts on the anaerobic system, a series of concentration from 0 to 40 mg L(-1) was tested. Biogas production was used as the indicator for NH4+ toxicity. The results showed no indication that methanogen was affected by the additional ammonium salt within the dosing regime. Application of the specific mathematical function (G=G(m)(k)(/t)) to describe the kinetic of biogas production, suggested that the optimal concentration of ammonium bicarbonate that can be used is 10 mg L(-1). This study also shows that the dosage regime up to 40 mg L(-1) can be used to supplement the lack of nitrogenous and buffering capacity for the anaerobic digestion process of the fruit cordial wastewater using CSTR. PMID:19450700

  10. Analysis of phosphorus removal and anaerobic selector performance in a full-scale activated sludge process in Singapore.

    PubMed

    Cao, Y S; Ang, C M; Raajeevan, K S; Kiran, A K; Lai, K C; Ng, S W; Zulkifli, I; Wah, Y L

    2006-01-01

    This paper analyses the performance of the anaerobic selector (A/O process) in a full-scale activated sludge process receiving mostly industrial sewage discharge (> 60%) in Singapore. In addition to the sludge settleability, enhanced biological phosphorus removal (EBPR) was studied. The sludge volume index (SVI) reduced from 200 to 80 ml g(-1) and foaming was suppressed significantly, indicating the effectiveness of the anaerobic selector in improving sludge settleability. The phosphorus removal efficiency was 66%, and 7.5 mg HAc-COD was consumed per mg PO4(3-) -P removed. In the anaerobic compartment, 31% of the SCOD and 73% of the acetic acid in the settled sewage were removed with PO4(3-) -P release of 14.1 mg PO4(3-)-P l(-1). The linear correlation between PO4(3-) -P release in the anaerobic compartment and PO4(3-) -P uptake in the aerobic compartment indicates that there is about 0.8 mg PO4(3-) -P release in the anaerobic compartment per mg PO34(3-) -P uptake in the aerobic compartment. The fates of volatile fatty acids (VFAs) and its short chain acids (SCAs) in the process were studied and discussed.

  11. Anaerobic methanotrophy in tidal wetland: Effects of electron acceptors

    NASA Astrophysics Data System (ADS)

    Lin, Li-Hung; Yu, Zih-Huei; Wang, Pei-Ling

    2016-04-01

    Wetlands have been considered to represent the largest natural source of methane emission, contributing substantially to intensify greenhouse effect. Despite in situ methanogenesis fueled by organic degradation, methanotrophy also plays a vital role in controlling the exact quantity of methane release across the air-sediment interface. As wetlands constantly experience various disturbances of anthropogenic activities, biological burrowing, tidal inundation, and plant development, rapid elemental turnover would enable various electron acceptors available for anaerobic methanotrophy. The effects of electron acceptors on stimulating anaerobic methanotrophy and the population compositions involved in carbon transformation in wetland sediments are poorly explored. In this study, sediments recovered from tidally influenced, mangrove covered wetland in northern Taiwan were incubated under the static conditions to investigate whether anaerobic methanotrophy could be stimulated by the presence of individual electron acceptors. Our results demonstrated that anaerobic methanotrophy was clearly stimulated in incubations amended with no electron acceptor, sulfate, or Fe-oxyhydroxide. No apparent methane consumption was observed in incubations with nitrate, citrate, fumarate or Mn-oxides. Anaerobic methanotrophy in incubations with no exogenous electron acceptor appears to proceed at the greatest rates, being sequentially followed by incubations with sulfate and Fe-oxyhydroxide. The presence of basal salt solution stimulated methane oxidation by a factor of 2 to 3. In addition to the direct impact of electron acceptor and basal salts, incubations with sediments retrieved from low tide period yielded a lower rate of methane oxidation than from high tide period. Overall, this study demonstrates that anaerobic methanotrophy in wetland sediments could proceed under various treatments of electron acceptors. Low sulfate content is not a critical factor in inhibiting methane

  12. Mechanisms of granular activated carbon anaerobic fluidized-bed process for treating phenols wastewater.

    PubMed

    Lao, Shan-gen

    2002-01-01

    Granular activated carbon (GAC) anaerobic fluidized-bed reactor was applied to treating phenols wastewater. When influent phenol concentration was 1000 mg/L, volume loadings of phenol and CODCr were 0.39 kg/(m3.d) and 0.98 kg/(m3.d), their removal rates were 99.9% and 96.4% respectively. From analyzing above results, the main mechanisms of the process are that through fluidizing GAC, its adsorption is combined with biodegradation, both activities are brought into full play, and phenol in wastewater is effectively decomposed. Meanwhile problems concerning gas-liquid separation and medium plugging are well solved. PMID:11887310

  13. Bioremediation of trichloroethylene contaminated groundwater using anaerobic process.

    PubMed

    Chomsurin, Cheema; Kajorntraidej, Juthathip; Luangmuang, Kongrit

    2008-01-01

    Anaerobic remediation of trichloroethylene (TCE) contaminated soil and groundwater was studied in laboratory setups. In this process fermentation of polymeric organic materials (POMS) produced volatile fatty acids (VFAs) that were electron donors in reductive dechlorination of TCE. Shredded peanut shell was selected as low cost POM and the experiments were set up in 500 ml Erlenmeyer flasks. In the setups, approximately 25 mg of leachate contaminated soil was used as the main source of microorganisms and about 5 g of shredded peanut shell (0.5-2.36 mm) was added to produce VFAs for dechlorination of TCE. In the first set of experiments, fermentation of soil and shredded peanut shell was studied and it was found that VFAs were produced continuously with increasing concentration (5.63 mM as CH3COOH from the first day to 17.17 in the 10th day of the experiment). During the fermentation, concentration of ammonia-nitrogen was 22-50 mg/L, the ratio of VFA to NH3 was 15.29-23.44 and pH was 5.24-6.00. These results show that the system was appropriate for microorganism activities. In the second set of experiments, TCE (approximately 48 mg/L) was added to the fermentation system and remediation of TCE by reductive dechlorination was studied. It was found that 0.04(+/-0.01) mg TCE adsorbed to a gram of soil and peanut shells at the beginning of the experiment and based on mass balance of the system, TCE concentration in water was linearly reduced at the rate of 0.0098 mg/hr.

  14. Effective distribution of emulsified edible oil for enhanced anaerobic bioremediation

    NASA Astrophysics Data System (ADS)

    Borden, Robert C.

    2007-10-01

    Recent laboratory and field studies have shown that injection of emulsified edible oils can provide an effective, low-cost alternative for stimulating anaerobic biodegradation processes. A pilot-scale permeable reactive bio-barrier (PRBB) was installed at a perchlorate and chlorinated solvent impacted site by injecting 380 L of commercially available emulsion (EOS ®) containing emulsified soybean oil, food-grade surfactants, lactate, and yeast extract through ten direct push injection wells over a two day period. Soil cores collected six months after emulsion injection indicate the oil was distributed up to 5 m downgradient of the injection wells. A previously developed emulsion transport model was used to simulate emulsion transport and retention using independently estimated model parameters. While there was considerable variability in the soil sampling results, the model simulations generally agreed with the observed oil distribution at the field site. Model sensitivity analyses indicate that increasing the injection flow rate or diluting the oil with more water will have little effect on final oil distribution in the aquifer. The only effective approach for enhancing the spread of emulsified oil away from the injection well appears to be injecting a greater mass of oil.

  15. Effective distribution of emulsified edible oil for enhanced anaerobic bioremediation.

    PubMed

    Borden, Robert C

    2007-10-30

    Recent laboratory and field studies have shown that injection of emulsified edible oils can provide an effective, low-cost alternative for stimulating anaerobic biodegradation processes. A pilot-scale permeable reactive bio-barrier (PRBB) was installed at a perchlorate and chlorinated solvent impacted site by injecting 380 L of commercially available emulsion (EOS) containing emulsified soybean oil, food-grade surfactants, lactate, and yeast extract through ten direct push injection wells over a two day period. Soil cores collected six months after emulsion injection indicate the oil was distributed up to 5 m downgradient of the injection wells. A previously developed emulsion transport model was used to simulate emulsion transport and retention using independently estimated model parameters. While there was considerable variability in the soil sampling results, the model simulations generally agreed with the observed oil distribution at the field site. Model sensitivity analyses indicate that increasing the injection flow rate or diluting the oil with more water will have little effect on final oil distribution in the aquifer. The only effective approach for enhancing the spread of emulsified oil away from the injection well appears to be injecting a greater mass of oil. PMID:17673332

  16. Anaerobic Digestion. Instructor's Guide. Biological Treatment Process Control.

    ERIC Educational Resources Information Center

    Carnegie, John W., Ed.

    This instructor's guide contains materials needed to teach a four-lesson unit on anaerobic digestion control. These materials include: (1) unit overview; (2) lesson plans; (3) lecture outlines; (4) student worksheets for each lesson (with answers); and (5) two copies of a final quiz (with and without answers). Lesson 1 is a review of the theory of…

  17. Aerobic and anaerobic nitrogen transformation processes in N2-fixing cyanobacterial aggregates

    PubMed Central

    Klawonn, Isabell; Bonaglia, Stefano; Brüchert, Volker; Ploug, Helle

    2015-01-01

    Colonies of N2-fixing cyanobacteria are key players in supplying new nitrogen to the ocean, but the biological fate of this fixed nitrogen remains poorly constrained. Here, we report on aerobic and anaerobic microbial nitrogen transformation processes that co-occur within millimetre-sized cyanobacterial aggregates (Nodularia spumigena) collected in aerated surface waters in the Baltic Sea. Microelectrode profiles showed steep oxygen gradients inside the aggregates and the potential for nitrous oxide production in the aggregates' anoxic centres. 15N-isotope labelling experiments and nutrient analyses revealed that N2 fixation, ammonification, nitrification, nitrate reduction to ammonium, denitrification and possibly anaerobic ammonium oxidation (anammox) can co-occur within these consortia. Thus, N. spumigena aggregates are potential sites of nitrogen gain, recycling and loss. Rates of nitrate reduction to ammonium and N2 were limited by low internal nitrification rates and low concentrations of nitrate in the ambient water. Presumably, patterns of N-transformation processes similar to those observed in this study arise also in other phytoplankton colonies, marine snow and fecal pellets. Anoxic microniches, as a pre-condition for anaerobic nitrogen transformations, may occur within large aggregates (⩾1 mm) even when suspended in fully oxygenated waters, whereas anoxia in small aggregates (<1 to ⩾0.1 mm) may only arise in low-oxygenated waters (⩽25 μM). We propose that the net effect of aggregates on nitrogen loss is negligible in NO3−-depleted, fully oxygenated (surface) waters. In NO3−-enriched (>1.5 μM), O2-depleted water layers, for example, in the chemocline of the Baltic Sea or the oceanic mesopelagic zone, aggregates may promote N-recycling and -loss processes. PMID:25575306

  18. Aerobic and anaerobic nitrogen transformation processes in N2-fixing cyanobacterial aggregates.

    PubMed

    Klawonn, Isabell; Bonaglia, Stefano; Brüchert, Volker; Ploug, Helle

    2015-06-01

    Colonies of N(2)-fixing cyanobacteria are key players in supplying new nitrogen to the ocean, but the biological fate of this fixed nitrogen remains poorly constrained. Here, we report on aerobic and anaerobic microbial nitrogen transformation processes that co-occur within millimetre-sized cyanobacterial aggregates (Nodularia spumigena) collected in aerated surface waters in the Baltic Sea. Microelectrode profiles showed steep oxygen gradients inside the aggregates and the potential for nitrous oxide production in the aggregates' anoxic centres. (15)N-isotope labelling experiments and nutrient analyses revealed that N(2) fixation, ammonification, nitrification, nitrate reduction to ammonium, denitrification and possibly anaerobic ammonium oxidation (anammox) can co-occur within these consortia. Thus, N. spumigena aggregates are potential sites of nitrogen gain, recycling and loss. Rates of nitrate reduction to ammonium and N(2) were limited by low internal nitrification rates and low concentrations of nitrate in the ambient water. Presumably, patterns of N-transformation processes similar to those observed in this study arise also in other phytoplankton colonies, marine snow and fecal pellets. Anoxic microniches, as a pre-condition for anaerobic nitrogen transformations, may occur within large aggregates (⩾1 mm) even when suspended in fully oxygenated waters, whereas anoxia in small aggregates (<1 to ⩾0.1 mm) may only arise in low-oxygenated waters (⩽25 μM). We propose that the net effect of aggregates on nitrogen loss is negligible in NO(3)(-)-depleted, fully oxygenated (surface) waters. In NO(3)(-)-enriched (>1.5 μM), O(2)-depleted water layers, for example, in the chemocline of the Baltic Sea or the oceanic mesopelagic zone, aggregates may promote N-recycling and -loss processes.

  19. Suitability of anaerobic digestion effluent as process water for corn fuel ethanol fermentation.

    PubMed

    Wang, Ke; Zhang, Jian-Hua; Liu, Pei; Mao, Zhong-Gui

    2014-01-01

    A corn fuel ethanol plant integrated with anaerobic digestion treatment of thin stillage increases the net energy balance. Furthermore, the anaerobic digestion effluent (ADE) can be reused as a potential substitute for process water in the ethanol fermentation. In this study, the suitability of ADE as process water for corn ethanol fermentation was investigated by analyzing the potential inhibitory components in the ADE. It was found that ammonium influenced the growth and metabolism of Saccharomyces cerevisiae. Maximum ethanol production was obtained when the concentration of ammonium nitrogen was 200 mg/L, and ammonium could replace urea as the nitrogen source for S. cerevisiae under this concentration. In the ethanol fermentation with a higher concentration of ammonium, more glycerol was produced, thereby resulting in the decrease of ethanol production. In addition, components except ammonium in the ADE caused no inhibition to ethanol production. These results suggest that ADE could be reused as process water for corn ethanol fermentation without negative effect when ammonium concentration is well controlled.

  20. Hydroponic potato production on nutrients derived from anaerobically-processed potato plant residues

    NASA Astrophysics Data System (ADS)

    Mackowiak, C. L.; Stutte, G. W.; Garland, J. L.; Finger, B. W.; Ruffe, L. M.

    1997-01-01

    Bioregenerative methods are being developed for recycling plant minerals from harvested inedible biomass as part of NASA's Advanced Life Support (ALS) research. Anaerobic processing produces secondary metabolites, a food source for yeast production, while providing a source of water soluble nutrients for plant growth. Since NH_4-N is the nitrogen product, processing the effluent through a nitrification reactor was used to convert this to NO_3-N, a more acceptable form for plants. Potato (Solanum tuberosum L.) cv. Norland plants were used to test the effects of anaerobically-produced effluent after processing through a yeast reactor or nitrification reactor. These treatments were compared to a mixed-N treatment (75:25, NO_3:NH_4) or a NO_3-N control, both containing only reagent-grade salts. Plant growth and tuber yields were greatest in the NO_3-N control and yeast reactor effluent treatments, which is noteworthy, considering the yeast reactor treatment had high organic loading in the nutrient solution and concomitant microbial activity.

  1. Anaerobic co-digestion of livestock wastes with vegetable processing wastes: a statistical analysis.

    PubMed

    Molinuevo-Salces, Beatriz; García-González, María Cruz; González-Fernández, Cristina; Cuetos, María José; Morán, Antonio; Gómez, Xiomar

    2010-12-01

    Anaerobic digestion of livestock wastes with carbon rich residues was studied. Swine manure and poultry litter were selected as livestock waste, and vegetable processing waste was selected as the rich carbon source. A Central Composite Design (CCD) and Response Surface Methodology (RSM) were employed in designing experiments and determine individual and interactive effects over methane production and removal of volatile solids. In the case of swine manure co-digestion, an increase in vegetable processing waste resulted in higher volatile solids removal. However, without a proper substrate/biomass ratio, buffer capacity of swine manure was not able to avoid inhibitory effects associated with TVFA accumulation. Regarding co-digestion with poultry litter, substrate concentration determined VS removal achieved, above 80 g VSL(-1), NH(3) inhibition was detected. Statistical analysis allowed us to set initial conditions and parameters to achieve best outputs for real-scale plant operation and/or co-digestion mixtures design.

  2. The alkaloid gramine in the anaerobic digestion process-inhibition and adaptation of the methanogenic community.

    PubMed

    Popp, Denny; Harms, Hauke; Sträuber, Heike

    2016-08-01

    As many plant secondary metabolites have antimicrobial activity, microorganisms of the anaerobic digestion process might be affected when plant material rich in these compounds is digested. Hitherto, the effects of plant secondary metabolites on the anaerobic digestion process are poorly investigated. In this study, the alkaloid gramine, a constituent of reed canary grass, was added daily to a continuous co-digestion of grass silage and cow manure. A transient decrease of the methane yield by 17 % and a subsequent recovery was observed, but no effect on other process parameters. When gramine was infrequently spiked in higher amounts, the observed inhibitory effect was even more pronounced including a 53 % decrease of the methane yield and an increase of acetic acid concentrations up to 96 mM. However, the process recovered and the process parameters were finally at initial values (methane yield around 255 LN CH4 per gram volatile solids of substrate and acetic acid concentration lower than 2 mM). The bacterial communities of the reactors remained stable upon gramine addition. In contrast, the methanogenic community changed from a well-balanced mixture of five phylotypes towards a strong dominance of Methanosarcina (more than two thirds of the methanogenic community) while Methanosaeta disappeared. Batch inhibition assays revealed that acetic acid was only converted to methane via acetoclastic methanogenesis which was more strongly affected by gramine than hydrogenotrophic methanogenesis and acetogenesis. Hence, when acetoclastic methanogenesis is the dominant pathway, a shift of the methanogenic community is necessary to digest gramine-rich plant material. PMID:27138201

  3. Anaerobic digestion of food waste stabilized by lime mud from papermaking process.

    PubMed

    Zhang, Jishi; Wang, Qinqing; Zheng, Pengwei; Wang, Yusong

    2014-10-01

    The effects of lime mud from papermaking process (LMP) addition as buffer agent and inorganic nutrient on the anaerobic digestion stability of food waste (FW) were investigated under mesophilic conditions with the aim of avoiding volatile fatty acids accumulation, and inorganic elements deficiency. When LMP concentration ranged from 6.0 to 10g/L, the FW anaerobic digestion could maintain efficient and stable state. These advantages are attributed to the existence of Ca, Na, Mg, K, Fe, and alkaline substances that favor the methanogenic process. The highest CH4 yield of 272.8mL/g-VS was obtained at LMP and VS concentrations of 10.0 and 19.8g/L, respectively, with the corresponding lag-phase time of 3.84d and final pH of 8.4. The methanogens from residue digestates mainly consisted of Methanobrevibacter, coccus-type and sarcina-type methanogens with LMP addition compared to Methanobacteria in control. However, higher concentration of LMP inhibited methanogenic activities and methane production. PMID:25151070

  4. Anaerobic digestion of food waste stabilized by lime mud from papermaking process.

    PubMed

    Zhang, Jishi; Wang, Qinqing; Zheng, Pengwei; Wang, Yusong

    2014-10-01

    The effects of lime mud from papermaking process (LMP) addition as buffer agent and inorganic nutrient on the anaerobic digestion stability of food waste (FW) were investigated under mesophilic conditions with the aim of avoiding volatile fatty acids accumulation, and inorganic elements deficiency. When LMP concentration ranged from 6.0 to 10g/L, the FW anaerobic digestion could maintain efficient and stable state. These advantages are attributed to the existence of Ca, Na, Mg, K, Fe, and alkaline substances that favor the methanogenic process. The highest CH4 yield of 272.8mL/g-VS was obtained at LMP and VS concentrations of 10.0 and 19.8g/L, respectively, with the corresponding lag-phase time of 3.84d and final pH of 8.4. The methanogens from residue digestates mainly consisted of Methanobrevibacter, coccus-type and sarcina-type methanogens with LMP addition compared to Methanobacteria in control. However, higher concentration of LMP inhibited methanogenic activities and methane production.

  5. [A novel quantitative approach to study dynamic anaerobic process at micro scale].

    PubMed

    Zhang, Zhong-Liang; Wu, Jing; Jiang, Jian-Kai; Jiang, Jie; Li, Huai-Zhi

    2012-11-01

    Anaerobic digestion is attracting more and more interests because of its advantages such as low cost and recovery of clean energy etc. In order to overcome the drawbacks of the existed methods to study the dynamic anaerobic process, a novel microscopical quantitative approach at the granule level was developed combining both the microdevice and the quantitative image analysis techniques. This experiment displayed the process and characteristics of the gas production at static state for the first time and the results indicated that the method was of satisfactory repeatability. The gas production process at static state could be divided into three stages including rapid linear increasing stage, decelerated increasing stage and slow linear increasing stage. The rapid linear increasing stage was long and the biogas rate was high under high initial organic loading rate. The results showed that it was feasible to make the anaerobic process to be carried out in the microdevice; furthermore this novel method was reliable and could clearly display the dynamic process of the anaerobic reaction at the micro scale. The results are helpful to understand the anaerobic process.

  6. [Effects of Nitrate and CH4 on Anaerobic Oxidation of BETX in Landfill Cover Soils].

    PubMed

    Liu, Rong; Long, Yan; Wang, Li-li; He, Ting; Ye, Jin-shao

    2015-05-01

    BETX is one of the important components of stink organic gases in landfills, which simultaneously release much of greenhouse CH4. The microorganisms in landfill cover soils are able to degrade CH4 and BETX. Therefore, improving the capacity of biological oxidation of microorganisms in landfill cover soils can effectively reduce and control pollution caused by landfill gases. Some electron acceptors can couple to anaerobic oxidation of methane and some organic pollutants, thus eliminating methane and organic substances. Based on the above theory, this research investigated the effect of nitrate (NO3-) and CH4 on anaerobic degradation of benzene series (toluene, xylene and isopropyl benzene) with coexistence of SO4(2-) in landfill cover soils through static incubation experiment. The results showed that BTEX inhibited the degradation of CH4 without adding nitrate, however, BTEX instead improved the removal of CH4 after nitrate addition. Although single addition of nitrate or CH4 could improve the removal of BTEX in landfill cover soils, adding both of them could improve the removal of BTEX better as the removal efficiencies for benzene, toluene and isopropyl benzene were respectively reached 65%, 88% and 82%, much higher than those of 53%, 76% and 31% when not adding nitrate and CH4. The process of anaerobic methane oxidation coupled to nitrate reduction was able to synchronously improve anaerobic oxidation of BETX.

  7. A critical review on inhibition of anaerobic digestion process by excess ammonia.

    PubMed

    Rajagopal, Rajinikanth; Massé, Daniel I; Singh, Gursharan

    2013-09-01

    Ammonia plays a vital role in the performance and stability of anaerobic digestion (AD) of N-rich organic-feedstock. Several research works were carried-out to study the effect of ammonia on the efficiency of AD of agro-food, industrial and livestock wastes/wastewater. However, excess ammonia remains a critical hitch in AD process. The mechanism of ammonia-inhibition has also been studied and there is no simple strategy available to mitigate ammonia-toxicity, when it exceeds threshold inhibition-level. For successful operation of AD systems at higher ammonia-level, adequate choice of temperature, control of pH and C/N ratio, and utilization of acclimatized-microflora to higher ammonia concentrations may ensure a stable and undisturbed digestion. This review provides a critical summary of earlier and recent research conducted on ammonia-inhibition during the anaerobic degradation of organic substrates, especially, at high ammonia concentrations. This article emphasizes that more profound knowledge on parameters influencing ammonia-inhibition is needed to apply appropriate control strategies.

  8. Combined treatment of olive mill wastewater by Fenton's reagent and anaerobic biological process.

    PubMed

    Amor, Carlos; Lucas, Marco S; García, Juan; Dominguez, Joaquín R; De Heredia, J Beltrán; Peres, José A

    2015-01-01

    This work presents the application of Fenton's reagent process combined with anaerobic digestion to treat an olive mill wastewater (OMW). Firstly, OMW was pre-treated by chemical oxidation in a batch reactor with Fenton's reagent, using a fixed H2O2/COD ratio of 0.20, pH = 3.5 and a H2O2/Fe(2+) molar ratio of 15:1. This advanced oxidation treatment allowed reaching reductions of 17.6 and 82.5% of chemical oxygen demand (COD) and total polyphenols (TP), respectively. Secondly, OMW treatment by anaerobic digestion was performed using previously adapted microorganisms immobilized in Sepiolite. These biological tests were carried out varying the substrate concentration supplied to the reactor and COD conversions from 52 to 74% were obtained. Afterwards, Fenton's reagent followed by anaerobic digestion was applied to OMW treatment. This combined process presented a significant improvement on organic load removal, reaching COD degradations from 64 to 88%. Beyond the pollutant load removal, it was also monitored the yield of methane generated throughout anaerobic experiments. The methane produced ranged from 281 cm(3) to 322 cm(3) of CH4/g COD removed. Additionally, a methane generation kinetic study was performed using the Monod Model. The application of this model allowed observing a kinetic constant increase of the combined process (kFN = 0.036 h(-1)) when compared to the single anaerobic process (kF = 0.017 h(-1)).

  9. Relating Anaerobic Digestion Microbial Community and Process Function

    PubMed Central

    Venkiteshwaran, Kaushik; Bocher, Benjamin; Maki, James; Zitomer, Daniel

    2015-01-01

    Anaerobic digestion (AD) involves a consortium of microorganisms that convert substrates into biogas containing methane for renewable energy. The technology has suffered from the perception of being periodically unstable due to limited understanding of the relationship between microbial community structure and function. The emphasis of this review is to describe microbial communities in digesters and quantitative and qualitative relationships between community structure and digester function. Progress has been made in the past few decades to identify key microorganisms influencing AD. Yet, more work is required to realize robust, quantitative relationships between microbial community structure and functions such as methane production rate and resilience after perturbations. Other promising areas of research for improved AD may include methods to increase/control (1) hydrolysis rate, (2) direct interspecies electron transfer to methanogens, (3) community structure–function relationships of methanogens, (4) methanogenesis via acetate oxidation, and (5) bioaugmentation to study community–activity relationships or improve engineered bioprocesses. PMID:27127410

  10. Resource recovery and epidemiology of anaerobic wastewater treatment process in a controlled ecological life support system

    NASA Technical Reports Server (NTRS)

    Li, Ku-Yen; Hunt, Madelyn D.

    1995-01-01

    The results of work accomplished under two different areas: (1) Resource Recovery of an Anaerobic Wastewater Treatment process, and (2) Epidemiological Study of an Anaerobic Wastewater Treatment Process are documented. The first part of the work was to set up and test three anaerobic digesters and then run these three digesters with a NASA-simulated wastewater. The second part of the work was to use a multi-drug resistant strain of Salmonella choleraesuis as the indicator bacteria for the epidemiological study. Details of these two parts can be found in two master's theses and are described in Sections 3 and 4 of this report. Several important results condensed from these two parts are summarized in Section 2.

  11. Anaerobic digestion of post-hydrothermal liquefaction wastewater for improved energy efficiency of hydrothermal bioenergy processes.

    PubMed

    Zhou, Yan; Schideman, Lance; Zheng, Mingxia; Martin-Ryals, Ana; Li, Peng; Tommaso, Giovana; Zhang, Yuanhui

    2015-01-01

    Hydrothermal liquefaction (HTL) is a promising process for converting wet biomass and organic wastes into bio-crude oil. It also produces an aqueous product referred to as post-hydrothermal liquefaction wastewater (PHWW) containing up to 40% of the original feedstock carbon, which reduces the overall energy efficiency of the HTL process. This study investigated the feasibility of using anaerobic digestion (AD) to treat PHWW, with the aid of activated carbon. Results showed that successful AD occurred at relatively low concentrations of PHWW (≤ 6.7%), producing a biogas yield of 0.5 ml/mg CODremoved, and ∼53% energy recovery efficiency. Higher concentrations of PHWW (≥13.3%) had an inhibitory effect on the AD process, as indicated by delayed, slower, or no biogas production. Activated carbon was shown to effectively mitigate this inhibitory effect by enhancing biogas production and allowing digestion to proceed at higher PHWW concentrations (up to 33.3%), likely due to sequestering toxic organic compounds. The addition of activated carbon also increased the net energy recovery efficiency of AD with a relatively high concentration of PHWW (33.3%), taking into account the energy for producing activated carbon. These results suggest that AD is a feasible approach to treat PHWW, and to improve the energy efficiency of the HTL processes. PMID:26676001

  12. Anaerobic digestion of post-hydrothermal liquefaction wastewater for improved energy efficiency of hydrothermal bioenergy processes.

    PubMed

    Zhou, Yan; Schideman, Lance; Zheng, Mingxia; Martin-Ryals, Ana; Li, Peng; Tommaso, Giovana; Zhang, Yuanhui

    2015-01-01

    Hydrothermal liquefaction (HTL) is a promising process for converting wet biomass and organic wastes into bio-crude oil. It also produces an aqueous product referred to as post-hydrothermal liquefaction wastewater (PHWW) containing up to 40% of the original feedstock carbon, which reduces the overall energy efficiency of the HTL process. This study investigated the feasibility of using anaerobic digestion (AD) to treat PHWW, with the aid of activated carbon. Results showed that successful AD occurred at relatively low concentrations of PHWW (≤ 6.7%), producing a biogas yield of 0.5 ml/mg CODremoved, and ∼53% energy recovery efficiency. Higher concentrations of PHWW (≥13.3%) had an inhibitory effect on the AD process, as indicated by delayed, slower, or no biogas production. Activated carbon was shown to effectively mitigate this inhibitory effect by enhancing biogas production and allowing digestion to proceed at higher PHWW concentrations (up to 33.3%), likely due to sequestering toxic organic compounds. The addition of activated carbon also increased the net energy recovery efficiency of AD with a relatively high concentration of PHWW (33.3%), taking into account the energy for producing activated carbon. These results suggest that AD is a feasible approach to treat PHWW, and to improve the energy efficiency of the HTL processes.

  13. Isotope effects associated with the anaerobic oxidation of sulfite and thiosulfate by the photosynthetic bacterium, Chromatium vinosum

    NASA Technical Reports Server (NTRS)

    Fry, B.; Gest, H.; Hayes, J. M.

    1985-01-01

    The purple photosynthetic bacterium Chromatium vinosum, strain D, catalyzes several oxidations of reduced sulfur compounds under anaerobic conditions in the light: e.g., sulfide --> sulfur --> sulfate, sulfite --> sulfate, and thiosulfate --> sulfur + sulfate. Here it is shown that no sulfur isotope effect is associated with the last of these processes; isotopic compositions of the sulfur and sulfate produced can differ, however, if the sulfane and sulfonate positions within the thiosulfate have different isotopic compositions. In the second process, an observed change from an inverse to a normal isotope effect during oxidation of sulfite may indicate the operation of 2 enzymatic pathways. In contrast to heterotrophic anaerobic reduction of oxidized sulfur compounds, anaerobic oxidations of inorganic sulfur compounds by photosynthetic bacteria are characterized by relatively small isotope effects.

  14. The effect of anaerobic biomass drying and exposure to air on their recovery and evolution.

    PubMed

    Massalha, Nedal; Brenner, Asher; Sheindorf, Chaim; Sabbah, Isam

    2014-10-15

    The main goal of this study was to test the effect of various drying methods of granular anaerobic biomass on biomass survival, potential and rate of methane re-production, and structure. This may facilitate the development of drying methods to preserve excess anaerobic biomass in dry form for re-inoculation of existing digesters after process failure or wash out or for the start-up of new digesters. To that end, anaerobic granular biomass was collected from an up-flow anaerobic sludge blanket (UASB) reactor. The biomass was dried using two alternative methods: oven with air circulation at 50 °C for 24 h (DAO), and vacuum rotary evaporator at anaerobic conditions (DAN). For comparison, the control was a biomass with no drying (WET). Biomass samples were tested for specific methanogenic activity using synthetic wastewater. The microbial communities were also tested for viability using the LIVE/DEAD kit, and total biomass was initially quantified by qPCR targeting 16S rRNA genes. In addition, the mcrA functional gene was used s a target for the detection of the most abundant methanogens. Basic bacterial morphology classification was done by VIT(®) gene probe technology using a fluorescence microscope. Dried DAN and DAO biomasses required approximately four operational runs to recover their initial methanogenic activity compared to WET biomass. LIVE/DEAD results showed clear increases in the proportions of the viable biomass of the total bacterial communities over time, especially for the DAN and DAO samples. A comparison of the qPCR results of both DAN and DAO to the WET biomass showed that the methanogenic mcrA gene fraction of the total biomass population of 16S rRNA gene concentrations decreased moderately by about 17.2% in the samples of DAO and by approximately 6.7% in the samples of DAN over all runs after Run1.

  15. The anaerobic SBR process: basic principles for design and automation.

    PubMed

    Ruiz, C; Torrijos, M; Sousbie, P; Lebrato Martinez, J; Moletta, R

    2001-01-01

    This study has determined the purification performance and the basic principles for the design of an anaerobic SBR (ASBR) to be used to treat wastewater generated in the food industries. Two ASBR's were set up and one fed with a slaughterhouse effluent at low concentration, the other with concentrated dairy wastewater. The maximum loading rate applied should not exceed 4.5 g of COD/L/day for the dilute effluent and 6 g of COD/L/day for the concentrated effluent. At higher loading rates, the reactors become difficult to operate, mainly because of sludge removal problems, and purification efficiency declines. A detailed study of the kinetics (TOC, VFA, rate of biogas production) throughout one treatment cycle led to the development of a simple control strategy based on the monitoring of the biogas production rate which was then applied to the reactor treating the dairy wastewater. After automation, the reactor worked free of problems at an average pollution load of 5.4 g of COD/L/day.

  16. Feasibility tests for treating shampoo and hair colorant wastewaters using anaerobic processes.

    PubMed

    Ahammad, Shaikh Z; Yakubu, A; Dolfing, J; Mota, C; Graham, D W

    2012-01-01

    Wastes from the personal care product (PCP) industry are often high in biodegradable carbon, which makes them amenable to aerobic biological treatment, although process costs are usually high due to aeration inefficiencies, high electricity demand and production of large amounts of sludge. As such, anaerobic treatment technologies are being considered to lower net energy costs by reducing air use and increasing methane production. To assess the amenability of PCP wastes to anaerobic treatment, methane yields and rates were quantified in different anaerobic reactors treating typical PCP wastes, including wastes from shampoo and hair colorant products. Overall, shampoo wastes were more amenable to methanogenesis with almost double the methane yields compared with colour wastes. To assess relevant microbial guilds, qPCR was performed on reactor biomass samples. Methanosaetaceae abundances were always significantly higher than Methanosarcinaceae and Methanomicrobiales abundances (P < 0.05), and did not differ significantly between waste types. Although colour wastes were less amenable to anaerobic treatment than shampoo wastes, differences cannot be explained by relative microbial abundances and probably result from the presence of inhibiting compounds in hair colorants (e.g., oxidants) at higher levels. Results showed that anaerobic technologies have great potential for treating PCP wastes, but additional work is needed to establish the basis of elevated methane yields and inhibition, especially when colorant wastes are present.

  17. Characteristics of hydrogen and methane production from cornstalks by an augmented two- or three-stage anaerobic fermentation process.

    PubMed

    Lu, Yuan; Lai, Qiheng; Zhang, Chong; Zhao, Hongxin; Ma, Kun; Zhao, Xuebing; Chen, Hongzhang; Liu, Dehua; Xing, Xin-Hui

    2009-06-01

    This paper presents the co-production of hydrogen and methane from cornstalks by a two- or three-stage anaerobic fermentation process augmented with effective artificial microbial community. Two-stage fermentation by using the anaerobic sludge and DGGE analysis showed that effective and stable strains should be introduced into the system. We introduced Enterobacter aerogens or Clostridium paraputrificum into the hydrogen stage, and C. paraputrificum was proven to be more effective. In the three-stage process consisting of the improved hydrolysis, hydrogen and methane production stages, the highest soluble sugars (0.482 kg/kg cornstalks) were obtained after the introduction of Clostridium thermocellum in the hydrolysis stage, under the thermophilic (55 degrees C) and acidic (pH 5.0) conditions. Hydrolysates from 1 kg of cornstalks could produce 2.61 mol (63.7 l) hydrogen by augmentation with C. paraputrificum and 4.69 mol (114.6 l) methane by anaerobic granular sludge, corresponding to 54.1% energy recovery.

  18. Effects of ionic strength and ion pairing on (plant-wide) modelling of anaerobic digestion.

    PubMed

    Solon, Kimberly; Flores-Alsina, Xavier; Mbamba, Christian Kazadi; Volcke, Eveline I P; Tait, Stephan; Batstone, Damien; Gernaey, Krist V; Jeppsson, Ulf

    2015-03-01

    Plant-wide models of wastewater treatment (such as the Benchmark Simulation Model No. 2 or BSM2) are gaining popularity for use in holistic virtual studies of treatment plant control and operations. The objective of this study is to show the influence of ionic strength (as activity corrections) and ion pairing on modelling of anaerobic digestion processes in such plant-wide models of wastewater treatment. Using the BSM2 as a case study with a number of model variants and cationic load scenarios, this paper presents the effects of an improved physico-chemical description on model predictions and overall plant performance indicators, namely effluent quality index (EQI) and operational cost index (OCI). The acid-base equilibria implemented in the Anaerobic Digestion Model No. 1 (ADM1) are modified to account for non-ideal aqueous-phase chemistry. The model corrects for ionic strength via the Davies approach to consider chemical activities instead of molar concentrations. A speciation sub-routine based on a multi-dimensional Newton-Raphson (NR) iteration method is developed to address algebraic interdependencies. The model also includes ion pairs that play an important role in wastewater treatment. The paper describes: 1) how the anaerobic digester performance is affected by physico-chemical corrections; 2) the effect on pH and the anaerobic digestion products (CO2, CH4 and H2); and, 3) how these variations are propagated from the sludge treatment to the water line. Results at high ionic strength demonstrate that corrections to account for non-ideal conditions lead to significant differences in predicted process performance (up to 18% for effluent quality and 7% for operational cost) but that for pH prediction, activity corrections are more important than ion pairing effects. Both are likely to be required when precipitation is to be modelled.

  19. 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.

  20. 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

  1. Anaerobic digestion of municipal solid waste: Utility of process residues as a soil amendment

    SciTech Connect

    Rivard, C.J.; Nagle, N.J.; Kay, B.D.

    1995-12-31

    Tuna processing wastes (sludges high in fat, oil, and grease [FOG]) and municipal solid waste (MSW) generated on Tutuila Island, American Samoa, represent an ongoing disposal challenge. The biological conversion of the organic fraction of these wastes to useful products, including methane and fertilizer-grade residue, through anaerobic high-solids digestion is currently in scale-up development. The suitability of the anaerobic digestion residues as a soil amendment was evaluated through extensive chemical analysis and greenhouse studies using corn as an indicator crop. Additionally, native Samoan soil was used to evaluate the specific application rates for the compost. Experiments established that anaerobic residues increase crop yields in direct proportion to increases in the application rate. Additionally, nutrient saturation was not demonstrated within the range of application rates evaluated for the Samoan soil. Beyond nutrient supplementation, organic residue amendment to Samoan soil imparts enhanced water and nutrient-binding capacities.

  2. 40 CFR Table II-2 to Subpart II - Collection Efficiencies of Anaerobic Processes

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Collection Efficiencies of Anaerobic Processes II Table II-2 to Subpart II Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Industrial Wastewater Treatment Pt....

  3. 40 CFR Table II-2 to Subpart II - Collection Efficiencies of Anaerobic Processes

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Collection Efficiencies of Anaerobic Processes II Table II-2 to Subpart II Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Industrial Wastewater Treatment Pt....

  4. Biohydrogen Production from Cheese Processing Wastewater by Anaerobic Fermentation Using Mixed Microbial Communities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hydrogen (H2) production from simulated cheese processing wastewater via anaerobic fermentation was conducted using mixed microbial communities under mesophilic conditions. In batch H2 fermentation experiments H2 yields of 8 and 10 mM/g-COD fed were achieved at food-to-microorganism (F/M) ratios of ...

  5. Effect of oxygen on the microbial activities of thermophilic anaerobic biomass.

    PubMed

    Pedizzi, C; Regueiro, L; Rodriguez-Verde, I; Lema, J M; Carballa, M

    2016-07-01

    Low oxygen levels (μgO2L(-1)) in anaerobic reactors are quite common and no relevant consequences are expected. On the contrary, higher concentrations could affect the process. This work aimed to study the influence of oxygen (4.3 and 8.8mgO2L(-1), respectively) on the different microbial activities (hydrolytic, acidogenic and methanogenic) of thermophilic anaerobic biomass and on the methanogenic community structure. Batch tests in presence of oxygen were conducted using specific substrates for each biological activity and a blank (with minimum oxygen) was included. No effect of oxygen was observed on the hydrolytic and acidogenic activities. In contrast, the methane production rate decreased by 40% in all oxygenated batches and the development of active archaeal community was slower in presence of 8.8mgO2L(-1). However, despite this sensitivity of methanogens to oxygen at saturation levels, the inhibition was reversible. PMID:27020398

  6. Effect of sodium salt on anaerobic digestion of kitchen waste.

    PubMed

    Anwar, Naveed; Wang, Wen; Zhang, Jie; Li, Yeqing; Chen, Chang; Liu, Guangqing; Zhang, Ruihong

    2016-01-01

    The effect of different sodium salt concentration on anaerobic digestion of kitchen waste was investigated. The methane production performance, the corresponding methane production model and sodium salt inhibition model were studied, and the degradation efficiency was analyzed. With the increase of sodium salt concentration, the methane yield and the maximal methane production rate decreased along with the increase of lag phase time. The highest methane yield of 594 mL/g-VSadded (VS: volatile solids) was found with no sodium salt addition while the lowest was obtained with addition of 16 g/L NaCl. The declines of the methane yield were negligible when the sodium salt concentration was below 8 g/L, which corresponded to <10% inhibiting efficiency. In contrast, a sharp decrease of methane yield was observed with addition of >8 g/L NaCl (causing 17-80% inhibition). Five kinds of regression models were developed to describe the sodium salt inhibition efficiency, and the cubic regression model of y = 0.508 + 2.401x - 0.369x(2) + 0.033x(3) showed the best fitting. The volatile fatty acids/ethanol gradually accumulated along with the increase of the sodium salt concentration, and the volatile solid removal efficiency represented a gradual decline accordingly. It is recommended that the sodium salt concentration in the anaerobic digesters should be controlled below 8 g/L in order to avoid intense methane inhibition. PMID:27120641

  7. Sludge exchange process on two serial CSTRs anaerobic digestions: process failure and recovery.

    PubMed

    Kafle, Gopi Krishna; Kim, Sang Hun

    2011-07-01

    The sludge exchange process using two anaerobic digesters (CSTRs) in series was investigated under the mesophilic condition (36-38°C). At first, the digesting sludge of the CSTRs in series with different TVFA/alkalinity ratios was tested in the laboratory by mixing the digesting sludge of two CSTRs from 6.5% to 50% based on volume. The sludge exchange test was then performed using the same CSTRs under batch and continuous processes. The change in the TVFA/alkalinity ratio was found to be linear with the digesting sludge exchange volume. The CSTR of TVFA/alkalinity ratio 1.970 recovered completely failed within 11 days for the batch process and the CSTR of TVFA/alkalinity ratio 1.514 within 3 weeks for the continuous feeding process at a sludge exchange volume of 13%. The reactor operation was stable when the TVFA/alkalinity ratio was less than 1.0 and when the TVFA concentration was lower than 10,000 mg L(-1).

  8. Comparison of methanogenic community structure and anaerobic process performance treating swine wastewater between pilot and optimized lab scale bioreactors.

    PubMed

    Kim, Woong; Cho, Kyungjin; Lee, Seungyong; Hwang, Seokhwan

    2013-10-01

    To investigate methanogenic community structure and process performance of anaerobic digestion treating swine wastewater at different scale, a pilot plant with 20 m(3) of effective working volume and lab scale methanogenic digester with 6L working volume were operated for 71 days and 6 turnover periods, respectively. During the steady state of anaerobic digestion, COD and VS removal efficiency in pilot plant were 65.3±3.2, 51.6±4.3%, respectively, which was similar to those in lab scale. However, calculated VFAs removal efficiency and methane yield were lower in pilot plant than in lab scale digester. Also, organics removal efficiencies, which consist of total carbohydrates, proteins, and lipids, were different between pilot and lab scale. These results were thought to be due to the ratio of carbohydrates to proteins in the raw swine wastewater. As a result of qualitative microbial analysis, Methanoculleus receptaculii, and Methanoculleus bourgensis, were commonly concerned with methane production.

  9. Start-up and inhibition analysis of the Anammox process seeded with anaerobic granular sludge.

    PubMed

    Tang, Chong-jian; Zheng, Ping; Mahmood, Qaisar; Chen, Jian-wei

    2009-08-01

    The longer start-up period of the Anammox process is due to the very low cellular yield and growth rates of Anammox bacteria. Nitrite inhibition is considered to be the key factor in the instability of the Anammox process during the operation. However, little attention was paid to the inhibitory effect of pH and free ammonia. This paper presents start-up and inhibition analysis of an Anammox biofilm reactor seeded with anaerobic granular sludge. Results showed that the start-up period could be divided into the sludge lysis phase, lag phase, propagation phase, stationary phase and inhibition phase. Optimization control could be implemented correspondingly to accelerate the start-up of Anammox bioreactors. Effluent pH increased to 8.7-9.1 when the nitrogen removal rate was higher than 1,200 mg l(-1) day(-1). The free ammonia concentration was accompanied with a higher level of 64-73 mg l(-1). Inhibitory effects of high pH and free ammonia on Anammox bacteria contributed to the destabilization of the Anammox bioreactor during the first 125 days with influent KHCO(3) of 0.5 g l(-1). Increasing the suffering capacity in the inlet by dosing 1.25 g KHCO(3) l(-1) effectively reduced the pH variation, and the nitrogen removal performance of the reactor was further developed.

  10. Treatment of olive oil mill wastewater by combined process electro-Fenton reaction and anaerobic digestion.

    PubMed

    Khoufi, Sonia; Aloui, Fathi; Sayadi, Sami

    2006-06-01

    In this work, we investigated an integrated technology for the treatment of the recalcitrant contaminants of olive mill wastewaters (OMW), allowing water recovery and reuse for agricultural purposes. The method involves an electrochemical pre-treatment step of the wastewater using the electro-Fenton reaction followed by an anaerobic bio-treatment. The electro-Fenton process removed 65.8% of the total polyphenolic compounds and subsequently decreased the OMW toxicity from 100% to 66.9%, which resulted in improving the performance of the anaerobic digestion. A continuous lab-scale methanogenic reactor was operated at a loading rate of 10 g chemical oxygen demand (COD)l(-1) d(-1) without any apparent toxicity. Furthermore, in the combined process, a high overall reduction in COD, suspended solids, polyphenols and lipid content was achieved by the two successive stages. This result opens promising perspectives since its conception as a fast and cheap pre-treatment prior to conventional anaerobic post-treatment. The use of electro-coagulation as post-treatment technology completely detoxified the anaerobic effluent and removed its toxic compounds. PMID:16678883

  11. Treatment of olive oil mill wastewater by combined process electro-Fenton reaction and anaerobic digestion.

    PubMed

    Khoufi, Sonia; Aloui, Fathi; Sayadi, Sami

    2006-06-01

    In this work, we investigated an integrated technology for the treatment of the recalcitrant contaminants of olive mill wastewaters (OMW), allowing water recovery and reuse for agricultural purposes. The method involves an electrochemical pre-treatment step of the wastewater using the electro-Fenton reaction followed by an anaerobic bio-treatment. The electro-Fenton process removed 65.8% of the total polyphenolic compounds and subsequently decreased the OMW toxicity from 100% to 66.9%, which resulted in improving the performance of the anaerobic digestion. A continuous lab-scale methanogenic reactor was operated at a loading rate of 10 g chemical oxygen demand (COD)l(-1) d(-1) without any apparent toxicity. Furthermore, in the combined process, a high overall reduction in COD, suspended solids, polyphenols and lipid content was achieved by the two successive stages. This result opens promising perspectives since its conception as a fast and cheap pre-treatment prior to conventional anaerobic post-treatment. The use of electro-coagulation as post-treatment technology completely detoxified the anaerobic effluent and removed its toxic compounds.

  12. Effect of anaerobic pretreatment on environmental and physicochemical characteristics of duckweed based stabilization ponds.

    PubMed

    Caicedo, J R; Espinosa, C; Andrade, M; Gijzen, H

    2002-01-01

    Duckweed based stabilization ponds, an alternative for wastewater treatment, are attracting a growing interest from researchers because they are basically a low cost technology, easy to built and operate, and produce tertiary quality effluents. Besides, this technology offers the possibility of resource recovery by producing high quality duckweed protein, which can be of further use. Since the technology is rather new, there are many aspects to be studied before its full-scale implementation. It is necessary to gain sound knowledge of the basic principles of the complex processes occurring in the system, as well as of the practical aspects of design and operation. The presence of a layer of duckweed on the surface is expected to produce different environmental and physicochemical conditions in the water from those found in conventional stabilization ponds. These environmental and physicochemical conditions affect both plant growth and biological treatment processes in the system, therefore it is important to determine their behavior in a duckweed system and how they can be affected by an anaerobic pretreatment. Continuous flow pilot plants composed of seven ponds in series were operated with artificial substrate under two different conditions: with anaerobic pretreatment and without anaerobic pretreatment. The flow was kept constant during the operation. Conditions such as pH, temperature, dissolved oxygen, alkalinity, conductivity, chemical oxygen demand, biochemical oxygen demand, total and ammonium nitrogen, nitrites and nitrates, and phosphorus were evaluated in the system under steady state conditions. The main conclusions from the study include the following: pH, temperature and oxygen profiles are more stable in duckweed ponds than in conventional stabilization ponds; anaerobic pretreatment has a significant effect on the oxygen concentration in the system and on the organic matter removal but not on the nutrient removal.

  13. Assessment of anaerobic bacterial diversity and its effects on anaerobic system stability and the occurrence of antibiotic resistance genes.

    PubMed

    Aydin, Sevcan; Ince, Bahar; Ince, Orhan

    2016-05-01

    This study evaluated the link between anaerobic bacterial diversity and, the biodegradation of antibiotic combinations and assessed how amending antibiotic combination and increasing concentration of antibiotics in a stepwise fashion influences the development of resistance genes in anaerobic reactors. The biodegradation, sorption and occurrence of the known antibiotic resistance genes (ARGs) of erythromycin and tetracycline were investigated using the processes of UV-HPLC and qPCR analysis respectively. Ion Torrent sequencing was used to detect microbial community changes in response to the addition of antibiotics. The overall results indicated that changes in the structure of a microbial community lead to changes in biodegradation capacity, sorption of antibiotics combinations and occurrence of ARGs. The enhanced biodegradation efficiency appeared to generate variations in the structure of the bacterial community. The results suggested that controlling the ultimate Gram-negative bacterial community, especially Acinetobacter-related populations, may promote the successful biodegradation of antibiotic combinations and reduce the occurrence of ARGs.

  14. Evaluation of granular anaerobic ammonium oxidation process for the disposal of pre-treated swine manure.

    PubMed

    Ni, Shou-Qing; Yang, Ning

    2014-01-01

    With rising environmental concerns on potable water safety and eutrophication, increased media attention and tighter environmental regulations, managing animal waste in an environmentally responsible and economically feasible way can be a challenge. In this study, the possibility of using granular anammox process for ammonia removal from swine waste treatment water was investigated. A rapid decrease of NO2 (-)-N and NH4 (+)-N was observed during incubation with wastewater from an activated sludge deodorization reactor and anaerobic digestion-partial oxidation treatment process treating swine manure and its corresponding control artificial wastewaters. Ammonium removal dropped from 98.0 ± 0.6% to 66.9 ± 2.7% and nearly absent when the organic load in the feeding increased from 232 mg COD/L to 1160 mg COD/L and 2320 mg COD/L. The presence of organic carbon had limited effect on nitrite and total nitrogen removal. At a COD to N ratio of 0.9, COD inhibitory organic load threshold concentration was 727 mg COD/L. Mass balance indicated that denitrifiers played an important role in nitrite, nitrate and organic carbon removal. These results demonstrated that anammox system had the potential to effectively treat swine manure that can achieve high nitrogen standards at reduced costs. PMID:24765570

  15. Evaluation of granular anaerobic ammonium oxidation process for the disposal of pre-treated swine manure

    PubMed Central

    Yang, Ning

    2014-01-01

    With rising environmental concerns on potable water safety and eutrophication, increased media attention and tighter environmental regulations, managing animal waste in an environmentally responsible and economically feasible way can be a challenge. In this study, the possibility of using granular anammox process for ammonia removal from swine waste treatment water was investigated. A rapid decrease of NO2−–N and NH4+–N was observed during incubation with wastewater from an activated sludge deodorization reactor and anaerobic digestion-partial oxidation treatment process treating swine manure and its corresponding control artificial wastewaters. Ammonium removal dropped from 98.0 ± 0.6% to 66.9 ± 2.7% and nearly absent when the organic load in the feeding increased from 232 mg COD/L to 1160 mg COD/L and 2320 mg COD/L. The presence of organic carbon had limited effect on nitrite and total nitrogen removal. At a COD to N ratio of 0.9, COD inhibitory organic load threshold concentration was 727 mg COD/L. Mass balance indicated that denitrifiers played an important role in nitrite, nitrate and organic carbon removal. These results demonstrated that anammox system had the potential to effectively treat swine manure that can achieve high nitrogen standards at reduced costs. PMID:24765570

  16. What are the differences between aerobic and anaerobic toxic effects of sulfonamides on Escherichia coli?

    PubMed

    Qin, Mengnan; Lin, Zhifen; Wang, Dali; Long, Xi; Zheng, Min; Qiu, Yanling

    2016-01-01

    Bacteria in the environment face the threat of antibiotics. However, most studies investigating the toxicity and toxicity mechanisms of antibiotics have been conducted on microorganisms in aerobic conditions, while studies examining the anaerobic toxicity and toxicity mechanisms of antibiotics are still limited. In this study, we determined the aerobic and anaerobic toxicities of sulfonamides (SAs) on Escherichia coli. Next, a comparison of the aerobic and anaerobic toxicities indicated that the SAs could be divided into three groups: Group I: log(1/EC50-anaerobic)>log(1/EC50-aerobic) (EC50-anaerobic/EC50-aerobic, the median effective concentration under anaerobic/aerobic conditions), Group II: log(1/EC50-anaerobic)≈log(1/EC50-aerobic), and Group III: log(1/EC50-anaerobic)anaerobic toxicities will benefit environmental science, and the results of this study will serve as a reference for the risk assessment of chemicals in the environment.

  17. [Anaerobic membrane bioreactors for treating agricultural and food processing wastewater at high strength].

    PubMed

    Wei, Yuan-Song; Yu, Da-Wei; Cao, Lei

    2014-04-01

    As the second largest amounts of COD discharged in 41 kinds of industrial wastewater, it is of great urgency for the agricultural and food processing industry to control water pollution and reduce pollutants. Generally the agricultural and food processing industrial wastewater with high strength COD of 8 000-30 000 mg x L(-1), is mainly treated with anaerobic and aerobic processes in series, but which exists some issues of long process, difficult maintenance and high operational costs. Through coupling anaerobic digestion and membrane separation together, anaerobic membrane bioreactor (AnMBR) has typical advantages of high COD removal efficiency (92%-99%), high COD organic loading rate [2.3-19.8 kg x (m3 x d)(-1)], little sludge discharged (SRT > 40 d) and low cost (HRT of 8-12 h). According to COD composition of high strength industrial wastewater, rate-limiting step of methanation could be either hydrolysis and acidification or methanogenesis. Compared with aerobic membrane bioreactor (MBR), membrane fouling of AnMBR is more complicated in characterization and more difficult in control. Measures for membrane fouling control of AnMBR are almost the same as those of MBR, including cross flow, air sparging and membrane relaxation. For meeting discharging standard of food processing wastewater with high strength, AnMBR is a promising technology with very short process, by enhancing COD removal efficiency, controlling membrane fouling and improving energy recovery.

  18. Enhanced Versus Conventional Sludge Anaerobic Processes: Performances and Techno-Economic Assessment.

    PubMed

    Gianico, Andrea; Bertanza, Giorgio; Braguglia, Camilla M; Canato, Matteo; Gallipoli, Agata; Laera, Giuseppe; Levantesi, Caterina; Mininni, Giuseppe

    2016-05-01

    Sewage sludge processing is a key issue in water resource recovery facilities due to the inefficacy of conventional treatments to produce high quality biosolids to be safely used in agriculture. Under this framework, the performances of several enhanced stabilization processes, namely ultrasound-pretreated Mesophilic Anaerobic Digestion (US+MAD), thermophilic anaerobic digestion (TAD), thermal-pretreated TAD (TH+TAD) and ultrasound-pretreated inverse Temperature Phased Anaerobic Digestion (US+iTPAD) have been investigated. Such enhanced processes resulted in higher biogas yields and higher destruction of pathogens with respect to conventional MAD process, thus suggesting their feasibility in full-scale implementation perspectives. A procedure for technical-economic comparison of new sludge processing lines against conventional ones (benchmarking) was developed, based on the definition of technical issues (e.g. reliability, complexity, etc.) which are rated for each situation. Moreover, capital and operating costs were estimated. The enhanced processes analyzed in this work showed some potentially critical items, mainly related to energy balance and reagent consumption. PMID:27131310

  19. Effect of ferrihydrite biomineralization on methanogenesis in an anaerobic incubation from paddy soil

    NASA Astrophysics Data System (ADS)

    Zhuang, Li; Xu, Jielong; Tang, Jia; Zhou, Shungui

    2015-05-01

    Microbial reduction of Fe(III) can be one of the major factors controlling methane production from anaerobic sedimentary environments, such as paddy soils and wetlands. Although secondary iron mineralization following Fe(III) reduction is a process that occurs naturally over time, it has not yet been considered in methanogenic systems. This study performed a long-term anaerobic incubation of a paddy soil and ferrihydrite-supplemented soil cultures to investigate methanogenesis during ferrihydrite biomineralization. The results revealed that the long-term effect of ferrihydrite on methanogenesis may be enhancement rather than suppression documented in previous studies. During initial microbial ferrihydrite reduction, methanogenesis was suppressed; however, the secondary minerals of magnetite formation was simultaneous with facilitated methanogenesis in terms of average methane production rate and acetate utilization rate. In the phase of magnetite formation, microbial community analysis revealed a strong stimulation of the bacterial Geobacter, Bacillus, and Sedimentibacter and the archaeal Methanosarcina in the ferrihydrite-supplemented cultures. Direct electric syntrophy between Geobacter and Methanosarcina via conductive magnetite is the plausible mechanism for methanogenesis acceleration along with magnetite formation. Our data suggested that a change in iron mineralogy might affect the conversion of anaerobic organic matter to methane and might provide a fresh perspective on the mitigation of methane emissions from paddy soils by ferric iron fertilization.

  20. Saponification pretreatment and solids recirculation as a new anaerobic process for the treatment of slaughterhouse waste.

    PubMed

    Affes, R; Palatsi, J; Flotats, X; Carrère, H; Steyer, J P; Battimelli, A

    2013-03-01

    Different configurations of anaerobic process, adapted to the treatment of solid slaughterhouse fatty waste, were proposed and evaluated in this study. The tested configurations are based on the combination of anaerobic digestion with/without waste saponification pretreatment (70 °C during 60 min) and with/without recirculation of the digestate solid fraction (ratio=20% w/w). After an acclimation period of substrate pulses-feeding cycles, the reactors were operated in a semi-continuous feeding mode, increasing organic loading rates along experimental time. The degradation of the raw substrate was shown to be the bottleneck of the whole process, obtaining the best performance and process yields in the reactor equipped with waste pretreatment and solids recirculation. Saponification promoted the emulsification and bioavailability of solid fatty residues, while recirculation of solids minimized the substrate/biomass wash-out and induced microbial adaptation to the treatment of fatty substrates.

  1. 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.

  2. Evaluation of an Anaerobic Digestion System for Processing CELSS Crop Residues for Resource Recovery

    NASA Technical Reports Server (NTRS)

    Strayer, R. F.; Finger, B. W.; Alazraki, M. P.

    1997-01-01

    Three bioreactors, connected in series, were used to process CELSS potato residues for recovery of resources. The first stage was an anaerobic digestor (8 L working volume; cow rumen contents inoculum; fed-batch; 8 day retention time; feed rate 25 gdw/day) that converted 33% of feed (dry weight loss) to CO2 and "volatile fatty acids" (vfa, 83:8:8 mmolar ratio acetic:propionic:butyric). High nitrate-N in the potato residue feed was absent in the anaerobic effluent, with a high portion converted to NH4(+)-N and the remainder unaccounted and probably lost to denitrification and NH4(+) volatilization. Liquid anaerobic effluent was fed to an aerobic, yeast biomass production vessel (2 L volume; Candida ingens inoculum; batch [pellicle] growth; 2 day retention time) where the VFAs and some NH4(+)-N were converted into yeast biomass. Yeast yields accounted for up to 8% of potato residue fed into the anaerobic bioreactor. The third bioreactor (0.5 L liquid working volume; commercial nitrifier inoculum; packed-bed biofilm; continuous yeast effluent feed; recirculating; constant volume; 2 day hydraulic retention time) was used to convert successfully the remaining NH4(+)-N into nitrate-N (preferred form of N for CELSS crop production) and to remove the remaining degradable soluble organic carbon. Effluents from the last two stages were used for partial replenishment of minerals for hydroponic potato production.

  3. Evaluation of an anaerobic digestion system for processing CELSS crop residues for resource recovery.

    PubMed

    Strayer, R F; Finger, B W; Alazraki, M P

    1997-01-01

    Three bioreactors, connected in series, were used to process CELSS potato residues for recovery of resources. The first stage was an anaerobic digestor (8 L working volume; cow rumen contents inoculum; fed-batch; 8 day retention time; feed rate 25 gdw day-1) that converted 33% of feed (dry weight loss) to CO2 and "volatile fatty acids" (vfa, 83:8:8 mmolar ratio acetic:propionic:butyric). High nitrate-N in the potato residue feed was absent in the anaerobic effluent, with a high portion converted to NH4(+)-N and the remainder unaccounted and probably lost to denitrification and NH4+ volatilization. Liquid anaerobic effluent was fed to an aerobic, yeast biomass production vessel (2 L volume; Candida ingens inoculum; batch [pellicle] growth; 2 day retention time) where the VFAs and some NH4(+)-N were converted into yeast biomass. Yeast yields accounted for up to 8% of potato residue fed into the anaerobic bioreactor. The third bioreactor (0.5 L liquid working volume; commercial nitrifier inoculum; packed-bed biofilm; continuous yeast effluent feed; recirculating; constant volume; 23 day hydraulic retention time) was used to convert successfully the remaining NH4(+)-N into nitrate-N (preferred form of N for CELSS crop production) and to remove the remaining degradable soluble organic carbon. Effluents from the last two stages were used for partial replenishment of minerals for hydroponic potato production.

  4. Evaluation of an anaerobic digestion system for processing CELSS crop residues for resource recovery

    NASA Astrophysics Data System (ADS)

    Strayer, R. F.; Finger, B. W.; Alazraki, M. P.

    1997-01-01

    Three bioreactors, connected in series, were used to process CELSS potato residues for recovery of resources. The first stage was an anaerobic digestor (8 L working volume; cow rumen contents inoculum; fed-batch; 8 day retention time; feed rate 25 gdw day^-1) that converted 33% of feed (dry weight loss) to CO_2 and ``volatile fatty acids'' (vfa, 83:8:8 mmolar ratio acetic:propionic:butyric). High nitrate-N in the potato residue feed was absent in the anaerobic effluent, with a high portion converted to NH_4^+-N and the remainder unaccounted and probably lost to denitrification and NH_4^+ volatilization. Liquid anaerobic effluent was fed to an aerobic, yeast biomass production vessel (2 L volume; Candida ingens inoculum; batch [pellicle] growth; 2 day retention time) where the VFAs and some NH_4^+-N were converted into yeast biomass. Yeast yields accounted for up to 8% of potato residue fed into the anaerobic bioreactor. The third bioreactor (0.5 L liquid working volume; commercial nitrifier inoculum; packed-bed biofilm; continuous yeast effluent feed; recirculating; constant volume; 2 day hydraulic retention time) was used to convert successfully the remaining NH_4^+-N into nitrate-N (preferred form of N for CELSS crop production) and to remove the remaining degradable soluble organic carbon. Effluents from the last two stages were used for partial replenishment of minerals for hydroponic potato production.

  5. Hybrid alkali-hydrodynamic disintegration of waste-activated sludge before two-stage anaerobic digestion process.

    PubMed

    Grübel, Klaudiusz; Suschka, Jan

    2015-05-01

    The first step of anaerobic digestion, the hydrolysis, is regarded as the rate-limiting step in the degradation of complex organic compounds, such as waste-activated sludge (WAS). The aim of lab-scale experiments was to pre-hydrolyze the sludge by means of low intensive alkaline sludge conditioning before applying hydrodynamic disintegration, as the pre-treatment procedure. Application of both processes as a hybrid disintegration sludge technology resulted in a higher organic matter release (soluble chemical oxygen demand (SCOD)) to the liquid sludge phase compared with the effects of processes conducted separately. The total SCOD after alkalization at 9 pH (pH in the range of 8.96-9.10, SCOD = 600 mg O2/L) and after hydrodynamic (SCOD = 1450 mg O2/L) disintegration equaled to 2050 mg/L. However, due to the synergistic effect, the obtained SCOD value amounted to 2800 mg/L, which constitutes an additional chemical oxygen demand (COD) dissolution of about 35 %. Similarly, the synergistic effect after alkalization at 10 pH was also obtained. The applied hybrid pre-hydrolysis technology resulted in a disintegration degree of 28-35%. The experiments aimed at selection of the most appropriate procedures in terms of optimal sludge digestion results, including high organic matter degradation (removal) and high biogas production. The analyzed soft hybrid technology influenced the effectiveness of mesophilic/thermophilic anaerobic digestion in a positive way and ensured the sludge minimization. The adopted pre-treatment technology (alkalization + hydrodynamic cavitation) resulted in 22-27% higher biogas production and 13-28% higher biogas yield. After two stages of anaerobic digestion (mesophilic conditions (MAD) + thermophilic anaerobic digestion (TAD)), the highest total solids (TS) reduction amounted to 45.6% and was received for the following sample at 7 days MAD + 17 days TAD. About 7% higher TS reduction was noticed compared with the sample after 9

  6. Hyperspectral imaging techniques applied to the monitoring of wine waste anaerobic digestion process

    NASA Astrophysics Data System (ADS)

    Serranti, Silvia; Fabbri, Andrea; Bonifazi, Giuseppe

    2012-11-01

    An anaerobic digestion process, finalized to biogas production, is characterized by different steps involving the variation of some chemical and physical parameters related to the presence of specific biomasses as: pH, chemical oxygen demand (COD), volatile solids, nitrate (NO3-) and phosphate (PO3-). A correct process characterization requires a periodical sampling of the organic mixture in the reactor and a further analysis of the samples by traditional chemical-physical methods. Such an approach is discontinuous, time-consuming and expensive. A new analytical approach based on hyperspectral imaging in the NIR field (1000 to 1700 nm) is investigated and critically evaluated, with reference to the monitoring of wine waste anaerobic digestion process. The application of the proposed technique was addressed to identify and demonstrate the correlation existing, in terms of quality and reliability of the results, between "classical" chemical-physical parameters and spectral features of the digestate samples. Good results were obtained, ranging from a R2=0.68 and a RMSECV=12.83 mg/l for nitrate to a R2=0.90 and a RMSECV=5495.16 mg O2/l for COD. The proposed approach seems very useful in setting up innovative control strategies allowing for full, continuous control of the anaerobic digestion process.

  7. Physicothermochemical pretreatments of food processing waste for enchancing anaerobic digestion and biogas generation

    SciTech Connect

    Azzam, A.M. Menoufia Univ., Sadat City ); Nasr, M.I. )

    1993-10-01

    This paper was conducted to evaluate the effect of milling and alkali lime cooking pretreatments on the rate and extent of methane generation from sugar Cane bagasse. The effect of pretreatment process variables (Particle size 8.0.003 mm, temperature between 100 and 250[degree]C and alkaline dosage between 0 and 8g CaO/kg VS) on the biogas generation from Sugar Cane bagasse has been investigated. Methane generation from the pretreated cane bagasse was studied using serum bottle technique and an upflow anaerobic filter bioreactor. The optimum condition involves alkali-cooking of cane bagasse (0.5 mm) with 4% CaO at 200[degree]C, dissolving most of the cellulose and converting it in a mixture of organic acids, including formic, acetic, lactic, and succinic acids. About 80% of the COD content of the cellulose was retained in the cooked liquor. A very rapid biogas were observed in the first three days of 70% methane content from the pretreated cane bagasse and the digestion was completed within 8 days. It has been concluded, that the lime-cooking of CB could produce methane as much as 70% of that from glucose. Inhibition did not seems to be serious problem in the biogas generation from the alkali-cooking cane bagasse. 29 refs., 3 figs., 5 tabs.

  8. Ammonia removal in food waste anaerobic digestion using a side-stream stripping process.

    PubMed

    Serna-Maza, A; Heaven, S; Banks, C J

    2014-01-01

    Three 35-L anaerobic digesters fed on source segregated food waste were coupled to side-stream ammonia stripping columns and operated semi-continuously over 300 days, with results in terms of performance and stability compared to those of a control digester without stripping. Biogas was used as the stripping medium, and the columns were operated under different conditions of temperature (55, 70, 85 °C), pH (unadjusted and pH 10), and RT (2-5 days). To reduce digester TAN concentrations to a useful level a high temperature (≥70 °C) and a pH of 10 were needed; under these conditions 48% of the TAN was removed over a 138-day period without any detrimental effects on digester performance. Other effects of the stripping process were an overall reduction in digestate organic nitrogen-containing fraction compared to the control and a recovery in the acetoclastic pathway when TAN concentration was 1770±20 mg kg(-1).

  9. Ammonia removal in food waste anaerobic digestion using a side-stream stripping process.

    PubMed

    Serna-Maza, A; Heaven, S; Banks, C J

    2014-01-01

    Three 35-L anaerobic digesters fed on source segregated food waste were coupled to side-stream ammonia stripping columns and operated semi-continuously over 300 days, with results in terms of performance and stability compared to those of a control digester without stripping. Biogas was used as the stripping medium, and the columns were operated under different conditions of temperature (55, 70, 85 °C), pH (unadjusted and pH 10), and RT (2-5 days). To reduce digester TAN concentrations to a useful level a high temperature (≥70 °C) and a pH of 10 were needed; under these conditions 48% of the TAN was removed over a 138-day period without any detrimental effects on digester performance. Other effects of the stripping process were an overall reduction in digestate organic nitrogen-containing fraction compared to the control and a recovery in the acetoclastic pathway when TAN concentration was 1770±20 mg kg(-1). PMID:24300847

  10. Kinetic evaluation and process performance of an upflow anaerobic filter reactor degrading terephthalic acid.

    PubMed

    Davutluoglu, Orkun I; Seckin, Galip

    2014-01-01

    The anaerobic degradation of terephthalic acid (TA) as the sole organic carbon source was studied in an upflow anaerobic filter (UAF) reactor. The reactor was seeded with biomass obtained from a full-scale upflow anaerobic sludge bed (UASB) reactor and was used to treat wastewater from a petrochemical facility producing dimethyl terephthalate. The UAF reactor was operated for 252 d with a constant hydraulic retention time of 24 h, and the organic loading rate (OLR) was gradually increased from 1 to 10 g-chemical oxygen demand (COD)/L d. After a lag period of approximately 40 d, the COD removal efficiency increased exponentially and high removal rate values (≈90%) were obtained, except for at highest OLR (10 g-COD/L d). The high removal rates and the robustness of the reactor performance could be attributed to the formation of biofilm as well as granular sludge. The methane production rates (0.22 to 2.15 L/d) correlated well with the removed OLRs (0.3 to 6.8 g-COD/L d) during the various phases of treatment, indicating that the main mechanism of TA degradation occurs via methanogenic reactions. The average methane content of the produced biogas was 70.3%. The modified Stover-Kincannon model was found to be applicable for the anaerobic degradation of TA in UAFs (Umax = 64.5, KB = 69.1 g-COD/L d and Ymax = 0.27 L-CH4/g-CODremoved). These results suggest that UAF reactors are among the most effective reactor configurations for the anaerobic degradation of TA.

  11. A novel process simulation model (PSM) for anaerobic digestion using Aspen Plus.

    PubMed

    Rajendran, Karthik; Kankanala, Harshavardhan R; Lundin, Magnus; Taherzadeh, Mohammad J

    2014-09-01

    A novel process simulation model (PSM) was developed for biogas production in anaerobic digesters using Aspen Plus®. The PSM is a library model of anaerobic digestion, which predicts the biogas production from any substrate at any given process condition. A total of 46 reactions were used in the model, which include inhibitions, rate-kinetics, pH, ammonia, volume, loading rate, and retention time. The hydrolysis reactions were based on the extent of the reaction, while the acidogenic, acetogenic, and methanogenic reactions were based on the kinetics. The PSM was validated against a variety of lab and industrial data on anaerobic digestion. The P-value after statistical analysis was found to be 0.701, which showed that there was no significant difference between discrete validations and processing conditions. The sensitivity analysis for a ±10% change in composition of substrate and extent of reaction results in 5.285% higher value than the experimental value. The model is available at http://hdl.handle.net/2320/12358 (Rajendran et al., 2013b).

  12. Research on Anaerobic Digestion: Optimization and Scalability of Mixed High-strength Food Processing Wastes for Renewable Biogas Energy

    SciTech Connect

    Yu, Zhongtang; Hitzhusen, Fredrick

    2012-12-27

    This research project developed and improved anaerobic digestion technologies, created a comprehensive Inventory of Ohio Biomass and a database of microorganisms of anaerobic digesters, and advanced knowledge and understanding of the underpinning microbiology of the anaerobic digestion process. The results and finding of this research project may be useful for future development and implementation of anaerobic digesters, especially at livestock farms. Policy makers and investors may also find the information on the biomass availability in Ohio and valuation of energy projects useful in policy making and making of investment decisions. The public may benefit from the information on biogas as an energy source and the potential impact of anaerobic digester projects on their neighborhoods.

  13. Effects of kinesio taping on anaerobic power recovery after eccentric exercise.

    PubMed

    Szymura, Jadwiga; Maciejczyk, Marcin; Wiecek, Magdalena; Maciejczyk, Grzegorz; Wiecha, Szczepan; Ochalek, Katarzyna; Kepinska, Magdalena; Szygula, Zbigniew

    2016-01-01

    The aim of the study was to evaluate the effectiveness of kinesio taping (KT) in anaerobic power recovery after eccentric exercise. The study was carried out on 10 healthy men. The participants performed two 60-min downhill runs with a constant intensity. Peak anaerobic power (PP) and mean power (MP) were measured before and five times after eccentric exercise. Anaerobic power was evaluated with the Maximal Cycling Sprint Test. After the downhill run, passive recovery (PR) and KT (lymphatic application) were applied in random order. A significant decrease in PP and MP was observed at least for 24 h after PR, compared to baseline. After the KT application 24 h after eccentric exercises, anaerobic power was already similar to the baseline measurement. The application of KT significantly improved anaerobic power recovery time after eccentric exercise compared to the period of passive rest immediately prior to testing. PMID:27362458

  14. The effect of cyclic anaerobic-aerobic conditions on biodegradation of azo dyes.

    PubMed

    Yaşar, Semra; Cirik, Kevser; Cinar, Ozer

    2012-03-01

    The effect of cyclic anaerobic-aerobic conditions on the biodegradative capability of the mixed microbial culture for the azo dye Remazol Brilliant Violet 5R (RBV-5R) was investigated in the sequencing batch reactor (SBR) fed with a synthetic textile wastewater. The SBR had a 12-h cycle time with anaerobic-aerobic periods of 3/9, 6/6 and 9/3 h. General SBR performance was assessed by measurement of catabolic enzymes (catechol 2,3-dioxygenase, azo reductase), chemical oxygen demand (COD), color and amount of aromatic amines. In this study, under steady-state conditions, the anaerobic period of the cyclic SBR was found to allow the reductive decolorization of azo dye. Longer anaerobic periods resulted in higher color removal efficiencies, approximately 71% for the 3-h, 87% for 6-h and 92% for the 9-h duration. Total COD removal efficiencies were over 84% under each of the cyclic conditions and increased as the length of the anaerobic period was increased; however, the highest color removal rate was attained for the cycle with the shortest anaerobic period of 3 h. During the decolorization of RBV-5R, two sulfonated aromatic amines (benzene based and naphthalene based) were formed. Additionally, anaerobic azo reductase enzyme was found to be positively affected with the increasing duration of the anaerobic period; however; it was vice versa for the aerobic catechol 2,3-dioxygenase (C23DO) enzyme.

  15. Start-up of an anaerobic/oxic process for phosphorus removal at the Northwest Quadrant Wastewater Treatment Plant

    SciTech Connect

    Not Available

    1992-08-01

    This study investigated the suitability and effectiveness of a proprietary anaerobic/oxic (A/0) process to facilitate the biological removal of phosphorus from domestic wastewater. The study took place at the Northwest Quadrant Wastewater Treatment Plant in Hilton, New York, and was conducted in conjunction with the New York State Energy Research Development Authority (the Energy Authority) and the Monroe County Department of Pure Waters. The NWQWWTP concentration limit for total effluent phosphorus is 1.0 mg/l. Influent phosphorus concentrations usually vary from 4 to 5 mg/l at the plant.

  16. Effect of alkaline pretreatment on anaerobic digestion of solid wastes.

    PubMed

    López Torres, M; Espinosa Lloréns, Ma del C

    2008-11-01

    The introduction of the anaerobic digestion for the treatment of the organic fraction of municipal solid waste (OFMSW) is currently of special interest. The main difficulty in the treatment of this waste fraction is its biotransformation, due to the complexity of organic material. Therefore, the first step must be its physical, chemical and biological pretreatment for breaking complex molecules into simple monomers, to increase solubilization of organic material and improve the efficiency of the anaerobic treatment in the second step. This paper describes chemical pretreatment based on lime addition (Ca(OH)2), in order to enhance chemical oxygen demand (COD) solubilization, followed by anaerobic digestion of the OFMSW. Laboratory-scale experiments were carried out in completely mixed reactors, 1 L capacity. Optimal conditions for COD solubilization in the first step of pretreatment were 62.0 mEq Ca(OH)2/L for 6.0 h. Under these conditions, 11.5% of the COD was solubilized. The anaerobic digestion efficiency of the OFMSW, with and without pretreatment, was evaluated. The highest methane yield under anaerobic digestion of the pretreated waste was 0.15 m3CH4/kg volatile solids (VS), 172.0% of the control. Under that condition the soluble COD and VS removal were 93.0% and 94.0%, respectively. The results have shown that chemical pretreatment with lime, followed by anaerobic digestion, provides the best results for stabilizing the OFMSW. PMID:18068345

  17. Effect of alkaline pretreatment on anaerobic digestion of solid wastes

    SciTech Connect

    Lopez Torres, M. Espinosa Llorens, Ma. del C.

    2008-11-15

    The introduction of the anaerobic digestion for the treatment of the organic fraction of municipal solid waste (OFMSW) is currently of special interest. The main difficulty in the treatment of this waste fraction is its biotransformation, due to the complexity of organic material. Therefore, the first step must be its physical, chemical and biological pretreatment for breaking complex molecules into simple monomers, to increase solubilization of organic material and improve the efficiency of the anaerobic treatment in the second step. This paper describes chemical pretreatment based on lime addition (Ca(OH){sub 2}), in order to enhance chemical oxygen demand (COD) solubilization, followed by anaerobic digestion of the OFMSW. Laboratory-scale experiments were carried out in completely mixed reactors, 1 L capacity. Optimal conditions for COD solubilization in the first step of pretreatment were 62.0 mEq Ca(OH){sub 2}/L for 6.0 h. Under these conditions, 11.5% of the COD was solubilized. The anaerobic digestion efficiency of the OFMSW, with and without pretreatment, was evaluated. The highest methane yield under anaerobic digestion of the pretreated waste was 0.15 m{sup 3} CH{sub 4}/kg volatile solids (VS), 172.0% of the control. Under that condition the soluble COD and VS removal were 93.0% and 94.0%, respectively. The results have shown that chemical pretreatment with lime, followed by anaerobic digestion, provides the best results for stabilizing the OFMSW.

  18. Effects of TNT and its metabolites on anaerobic TNT degradation

    SciTech Connect

    Roberts, D.J.; Pendharkar, S.; Ahmad, F.

    1998-07-01

    The effects of the presence of 2,4,6-trinitrotoluene (TNT), 4-amino-2,6-dinitrotoluene, and 2,4-diamino-6-nitrotoluene on the anaerobic treatment procedure developed for munitions-contaminated soil were examined. When 4-amino-2,6-dinitrotoluene was spiked in increasing levels into cultures containing TNT, inhibition of the rate of TNT degradation was observed. The degradation of 4-amino-2,6-dinitrotoluene did not proceed while TNT was present in the cultures. When 2,4-diamino-6-nitrotoluene was spiked into cultures that also contained TNT, TNT degradation rates were inhibited, and 4-amino-2,6-dinitrotoluene and 2,4-diamino-6-nitrotoluene were not degraded at all. When 2,4-diamino-6-nitrotoluene was spiked into cultures containing 4-amino-2,6-dinitrotoluene, degradation of 4-amino-2,6-dinitrotoluene was not effected but 2,4-diamino-6-nitrotoluene was not degraded. These results suggest that the rapid removal of TNT from the treatment system, before the intermediates have a chance to accumulate, or the rapid removal of the intermediates of TNT degradation is of utmost importance during the remediation of TNT-contaminated soils. If these intermediates are allowed to accumulate above inhibitory levels, the degradation of TNT will be slowed and the removal of the intermediates will halt completely.

  19. Characterization of products from hydrothermal carbonization of orange pomace including anaerobic digestibility of process liquor.

    PubMed

    Erdogan, Ezgi; Atila, Buse; Mumme, Jan; Reza, M Toufiq; Toptas, Asli; Elibol, Murat; Yanik, Jale

    2015-11-01

    In this study, the effect of the temperature and reaction time on hydrothermal carbonization (HTC) of orange pomace was investigated. In addition, a set of anaerobic batch tests were performed to determine the resulting biogas and methane potential of the spent liquor. Hydrochar yields followed a decreasing trend with the increasing temperature, whereas reaction time had no considerably effect on the yield. The evolution of the H/C and O/C atomic ratios from the raw material to the hydrochars suggested that dehydration reactions prevail during HTC. The hydrochars tended to become enriched in Ca, Mg and P minerals by increasing HTC temperature. The heavy metal contents in hydrochars were found below limits and no PAH compound was detected. Anaerobic digestion tests showed that the aqueous phase from HTC can be used as feedstocks for biogas production. PMID:26226579

  20. Combined anaerobic-ozonation process for treatment of textile wastewater: removal of acute toxicity and mutagenicity.

    PubMed

    Punzi, Marisa; Nilsson, Filip; Anbalagan, Anbarasan; Svensson, Britt-Marie; Jönsson, Karin; Mattiasson, Bo; Jonstrup, Maria

    2015-07-15

    A novel set up composed of an anaerobic biofilm reactor followed by ozonation was used for treatment of artificial and real textile effluents containing azo dyes. The biological treatment efficiently removed chemical oxygen demand and color. Ozonation further reduced the organic content of the effluents and was very important for the degradation of aromatic compounds, as shown by the reduction of UV absorbance. The acute toxicity toward Vibrio fischeri and the shrimp Artemia salina increased after the biological treatment. No toxicity was detected after ozonation with the exception of the synthetic effluent containing the highest concentration, 1 g/l, of the azo dye Remazol Red. Both untreated and biologically treated textile effluents were found to have mutagenic effects. The mutagenicity increased even further after 1 min of ozonation. No mutagenicity was however detected in the effluents subjected to longer exposure to ozone. The results of this study suggest that the use of ozonation as short post-treatment after a biological process can be beneficial for the degradation of recalcitrant compounds and the removal of toxicity of textile wastewater. However, monitoring of toxicity and especially mutagenicity is crucial and should always be used to assess the success of a treatment strategy.

  1. [Printing and dyeing wastewater treatment using combined process of anaerobic bioreactor and MBR].

    PubMed

    Zheng, Xiang; Liu, Jun-xin

    2004-09-01

    This paper describes a labor-scale experiment for printing and dyeing wastewater treatment of woolen mill using a combined process of an anaerobic reactor and a membrane bioreactor (MBR). The experimental results showed that when the concentration of COD, BOD5 and color in the influent were 128-321 mg/L, 36-95 mg/L and 40-70 dilution times (DT), the average concentrations of COD, BOD5, color and turbidity in the effluent were 36.9 mg/L, 3.7 mg/L, 21 DT and 0.24 NTU, respectively, and the corresponding removal rates were 80.3%, 95%, 59% and 99.3%, respectively. A new integrated membrane bioreactor by gravity drain of liquid level in the bioreactor was developed in this study. It not only lessens suction pump for effluent and controlling unit comparing to the traditional integrated membrane bioreactor, but also has the characters of high and continuous flux, concise configuration and simple operation and maintenance. According to the experimental results, the air flow rate through the membrane module is a significant factor to affect the flux rate and cake layer deposited on the membrane. With application of optimal air flow rate, it is effective to reduce membrane fouling and maintain high flux rate.

  2. Kinetics of phenol degradation in an anaerobic fixed-biofilm process

    SciTech Connect

    Lin, Y.H.; Lee, K.K.

    2006-06-15

    A mathematical model was developed to describe phenol degradation in an anaerobic fixed-biofilm process. The model incorporates the mechanisms of diffusive mass transport and Monod kinetics. The model was solved using a combination of the orthogonal collocation method and Gear's method. A pilot-scale column reactor was used to verify the model. Batch kinetic tests were conducted independently to determine the biokinetic parameters used in the model, while shear loss and initial thickness of biofilm were assumed so that the model simulated the substrate concentration results well. The removal efficiency for phenol was approximately 98.5% at a steady-state condition. The model accurately described the effluent substrate concentrations and the sequence of biodegradation in the reactor. The model simulations are in agreement with the experimental results. The approaches presented in this paper could be used to design full-scale anaerobic fixed-biofilm reactor systems for the biodegradation of phenolic substrates.

  3. Microbial fuel cell based biosensor for in situ monitoring of anaerobic digestion process.

    PubMed

    Liu, Zhidan; Liu, Jing; Zhang, Songping; Xing, Xin-Hui; Su, Zhiguo

    2011-11-01

    A wall-jet microbial fuel cell (MFC) was developed for the monitoring of anaerobic digestion (AD). This biofilm based MFC biosensor had a character of being portable, short hydraulic retention time (HRT) for sample flow through and convenient for continuous operation. The MFC was installed in the recirculation loop of an upflow anaerobic fixed-bed (UAFB) reactor in bench-scale where pH of the fermentation broth and biogas flow were monitored in real time. External disturbances to the AD were added on purpose by changing feedstock concentration, as well as process configuration. MFC signals had good correlations with online measurements (i.e. pH, gas flow rate) and offline analysis (i.e. COD) over 6-month operation. These results suggest that the MFC signal can reflect the dynamic variation of AD and can potentially be a valuable tool for monitoring and control of bioprocess.

  4. Bioelectrochemically-assisted anaerobic composting process enhancing compost maturity of dewatered sludge with synchronous electricity generation.

    PubMed

    Yu, Hang; Jiang, Junqiu; Zhao, Qingliang; Wang, Kun; Zhang, Yunshu; Zheng, Zhen; Hao, Xiaodi

    2015-10-01

    Bioelectrochemically-assisted anaerobic composting process (AnCBE) with dewatered sludge as the anode fuel was constructed to accelerate composting of dewatered sludge, which could increase the quality of the compost and harvest electric energy in comparison with the traditional anaerobic composting (AnC). Results revealed that the AnCBE yielded a voltage of 0.60 ± 0.02 V, and total COD (TCOD) removal reached 19.8 ± 0.2% at the end of 35 d. The maximum power density was 5.6 W/m(3). At the end of composting, organic matter content (OM) reduction rate increased to 19.5 ± 0.2% in AnCBE and to 12.9 ± 0.1% in AnC. The fuzzy comprehensive assessment (FCA) result indicated that the membership degree of class I of AnCBE compost (0.64) was higher than that of AnC compost (0.44). It was demonstrated that electrogenesis in the AnCBE could improve the sludge stabilization degree, accelerate anaerobic composting process and enhance composting maturity with bioelectricity generation.

  5. Thermophilic two-phase anaerobic digestion of source-sorted organic fraction of municipal solid waste for bio-hythane production: effect of recirculation sludge on process stability and microbiology over a long-term pilot-scale experience.

    PubMed

    Giuliano, A; Zanetti, L; Micolucci, F; Cavinato, C

    2014-01-01

    A two-stage thermophilic anaerobic digestion process for the concurrent production of hydrogen and methane through the treatment of the source-sorted organic fraction of municipal solid waste was carried out over a long-term pilot scale experience. Two continuously stirred tank reactors were operated for about 1 year. The results showed that stable production of bio-hythane without inoculum treatment could be obtained. The pH of the dark fermentation reactor was maintained in the optimal range for hydrogen-producing bacteria activity through sludge recirculation from a methanogenic reactor. An average specific bio-hythane production of 0.65 m(3) per kg of volatile solids fed was achieved when the recirculation flow was controlled through an evaporation unit in order to avoid inhibition problems for both microbial communities. Microbial analysis indicated that dominant bacterial species in the dark fermentation reactor are related to the Lactobacillus family, while the population of the methanogenic reactor was mainly composed of Defluviitoga tunisiensis. The archaeal community of the methanogenic reactor shifted, moving from Methanothermobacter-like to Methanobacteriales and Methanosarcinales, the latter found also in the dark fermentation reactor when a considerable methane production was detected.

  6. Characterization and single-stage denitrification anaerobic digestion of spent stream from the hydrolysis-fermentation-combustion process

    NASA Astrophysics Data System (ADS)

    Singh, Ramnik

    The demand for ethanol as an oxygenate and octane booster in automobile fuel is growing. A number of processes are being investigated for conversion of biomass to ethanol. The Hydrolysis-Fermentation-Combustion (HFC) process for fuel ethanol production developed at the University of California Forest Products Laboratory, Richmond, California is at the stage of technology transfer following over two decades of research and development. This study addresses the technology to be used in treatment of spent streams to be discharged from this process. The treatment design combines a single stage denitrification and anaerobic digestion (SSDAD) for the biological treatment of a representative stream from this process. A typical spent stream contained a wide range of soluble organic materials including: unfermented sugars, components of the feedstocks solubilized in the hydrolysis, acid degradation products of carbohydrates, cleavage products of lignin, water-soluble extractives and phenolics, terpenes and other unfermented organic material, and nitrate ion from the nitric acid used as a catalyst in the hydrolysis reaction. Three sets of experiments were conducted in laboratory scale anaerobic digesters. Commonly available anaerobic sludge from local sewage treatment plants was used as a starter seed and was successfully acclimated to the high nitrate substrate leading to enrichment of denitrifiers. Necessary nutrients and trace elements were identified and supplied to satisfy the obligatory requirements of different groups of bacterial groups present. A major finding was the unique role of ammonium hydroxide in controlling pH leading to steady-state operation of the digester. At steady state operation the reduction in COD was 65%, the nitrate reduction was 88% and the nitrite reduction was 100%. Nitrate was reduced to safe nitrogen gas without buildup of any intermediate products. Organic material was converted to useful methane gas and carbon dioxide. The SSDAD system was

  7. Effects of lipid concentration on anaerobic co-digestion of municipal biomass wastes

    SciTech Connect

    Sun, Yifei; Wang, Dian; Yan, Jiao; Qiao, Wei; Wang, Wei; Zhu, Tianle

    2014-06-01

    Highlights: • Lipid in municipal biomass would not inhibited the anaerobic digestion process. • A lipid concentration of 65% of total VS was the inhibition concentration. • The amount of Brevibacterium decreased with the increasing of the lipid contents. • Long chain fatty acids stacked on the methanogenic bacteria and blocked the mass transfer process. - Abstract: The influence of the lipid concentration on the anaerobic co-digestion of municipal biomass waste and waste-activated sludge was assessed by biochemical methane potential (BMP) tests and by bench-scale tests in a mesophilic semi-continuous stirred tank reactor. The effect of increasing the volatile solid (VS) concentration of lipid from 0% to 75% was investigated. BMP tests showed that lipids in municipal biomass waste could enhance the methane production. The results of bench-scale tests showed that a lipids concentration of 65% of total VS was the inhibition concentration. Methane yields increased with increasing lipid concentration when lipid concentrations were below 60%, but when lipid concentration was set as 65% or higher, methane yields decreased sharply. When lipid concentrations were below 60%, the pH values were in the optimum range for the growth of methanogenic bacteria and the ratios of volatile fatty acid (VFA)/alkalinity were in the range of 0.2–0.6. When lipid concentrations exceeded 65%, the pH values were below 5.2, the reactor was acidized and the values of VFA/alkalinity rose to 2.0. The amount of Brevibacterium decreased with increasing lipid content. Long chain fatty acids stacked on the methanogenic bacteria and blocked the mass transfer process, thereby inhibiting anaerobic digestion.

  8. Evaluation of anaerobic digestion processes for short sludge-age waste activated sludge combined with anammox treatment of digestate liquor.

    PubMed

    Ge, Huoqing; Batstone, Damien; Keller, Jurg

    2016-01-01

    The need to reduce energy input and enhance energy recovery from wastewater is driving renewed interest in high-rate activated sludge treatment (i.e. short hydraulic and solids retention times (HRT and SRT, respectively)). This process generates short SRT activated sludge stream, which should be highly degradable. However, the evaluation of anaerobic digestion of short SRT sludge has been limited. This paper assesses anaerobic digestion of short SRT sludge digestion derived from meat processing wastewater under thermophilic and mesophilic conditions. The thermophilic digestion system (55°C) achieved 60 and 68% volatile solids destruction at 8 day and 10 day HRT, respectively, compared with 50% in the mesophilic digestion system (35°C, 10 day HRT). The digestion effluents from the thermophilic (8-10 day HRT) and mesophilic systems were stable, as assessed by residual methane potentials. The ammonia rich sludge dewatering liquor was effectively treated by a batch anammox process, which exhibited comparable nitrogen removal rate as the tests using a control synthetic ammonia solution, indicating that the dewatering liquor did not have inhibiting/toxic effects on the anammox activity.

  9. Effect of simulated weightlessness on exercise-induced anaerobic threshold

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Karst, G. M.; Kirby, C. R.; Goldwater, D. J.

    1986-01-01

    The effect of simulated weightlessness, induced by ten days of continuous bedrest (BR) in the -6 deg head-down position, on the exercise-induced anaerobic threshold (AT) was determined by comparing specific ventilatory and gas-exchange measurements during an incremental ergometer test performed before and after BR. The primary index for determining the exercise-induced AT values of each subject was visual identification of the workrate or oxygen uptake (VO2) at which the ratio of the expired minute ventilation volume (VE) to VO2 exhibited a systematic increase without a concomitant increase in the VE/VCO2 value. Following BR, the mean VO2max of the subjects decreased by 7.0 percent, and the AT decreased from a mean of 1.26 L/min VO2 before BR to 0.95 L/min VO2 after BR. The decrease in AT was manifested by a decrease in both absolute and relative workrates. The change in AT correlated significantly with the change in plasma volume but not with the change in VO2max. The results suggest that the reduction in AT cannot be completely explained by the reduction in VO2, and that the AT decrease is associated with the reduction in intravascular fluid volume.

  10. Silver Sulfidation in Thermophilic Anaerobic Digesters and Effects on Antibiotic Resistance Genes

    SciTech Connect

    Kim, Bojeong; Miller, Jennifer H.; Monsegue, Niven; Levard, Clément; Hong, Yanjuan; Hull, Matthew S.; Murayama, Mitsuhiro; Brown, Gordon E.; Vikesland, Peter J.; Knocke, William R.; Pruden, Amy; Hochella, Michael F.

    2015-12-15

    Physical and chemical transformations and biological responses of silver nanoparticles (AgNPs) in wastewater treatment systems are of particular interest because of the extensive existing and continually growing uses of AgNPs in consumer products. In this study, we investigated the transformation of AgNPs and AgNO3 during thermophilic anaerobic digestion and effects on selection or transfer of antibiotic resistance genes (ARGs). Ag2S-NPs, sulfidation products of both AgNPs and AgNO3, were recovered from raw and digested sludges and were analyzed by analytical transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS). TEM and XAS revealed rapid (≤20 min) Ag sulfidation for both Ag treatments. Once transformed, Ag2S-NPs (as individual NPs or an NP aggregate) persisted for the duration of the batch digestion. The digestion process produced Ag2S-NPs that were strongly associated with sludge organics and/or other inorganic precipitates. Ag treatments (up to 1,000 mg Ag/kg) did not have an impact on the performance of thermophilic anaerobic digesters or ARG response, as indicated by quantitative polymerase chain reaction measurements of sul1, tet(W), and tet(O) and also intI1, an indicator of horizontal gene transfer of ARGs. Thus, rapid Ag sulfidation and stabilization with organics effectively sequester Ag and prevent biological interactions with the digester microbial community that could induce horizontal gene transfer or adversely impact digester performance through antimicrobial activity. This finding suggests that sulfide-rich anaerobic environments, such as digesters, likely have a high buffer capacity to mitigate the biological effects of AgNPs.

  11. Evaluation of a Ca-modified porphyritic andesite for ammonium removal in the anaerobic digestion process.

    PubMed

    Wang, Qinghong; Yang, Yingnan; Li, Dawei; Zhang, Zhenya

    2013-01-01

    In this study, a Ca-modified porphyritic andesite (wheat-rice-stone (WRS)) was developed for the anaerobic digestion of ammonium-rich wastes. The Ca-modified WRS was obtained with integrated Ca-salt treatment and calcination. Scanning electron microscope and Brunauer-Emmett-Teller surface area analyses were performed to characterize the Ca-modified WRS, and adsorption isotherms and kinetics were investigated to clarify the adsorption mechanism. The ammonium adsorption process was explained well with a pseudo-second-order kinetic model. The specific surface area of the Ca-modified WRS was determined to be 4.56 sq. m/g, and the maximum NH4(+)-N adsorption capacity was determined to be 45.45 mg/g. These values are improvements over those of natural WRS. The ammonium adsorption capacity remained constant at a pH range from 5.0 to 9.0, which indicates that Ca-modified WRS is a promising material for various applications. The methane-production and chemical oxygen demand-removal aspects of anaerobic digestion were much improved with the addition of Ca-modified WRS. Therefore, Ca-modified WRS could be developed into a viable ammonium adsorbent for the anaerobic digestion of ammonium-rich wastes.

  12. Evaluation of a Ca-modified porphyritic andesite for ammonium removal in the anaerobic digestion process.

    PubMed

    Wang, Qinghong; Yang, Yingnan; Li, Dawei; Zhang, Zhenya

    2013-01-01

    In this study, a Ca-modified porphyritic andesite (wheat-rice-stone (WRS)) was developed for the anaerobic digestion of ammonium-rich wastes. The Ca-modified WRS was obtained with integrated Ca-salt treatment and calcination. Scanning electron microscope and Brunauer-Emmett-Teller surface area analyses were performed to characterize the Ca-modified WRS, and adsorption isotherms and kinetics were investigated to clarify the adsorption mechanism. The ammonium adsorption process was explained well with a pseudo-second-order kinetic model. The specific surface area of the Ca-modified WRS was determined to be 4.56 sq. m/g, and the maximum NH4(+)-N adsorption capacity was determined to be 45.45 mg/g. These values are improvements over those of natural WRS. The ammonium adsorption capacity remained constant at a pH range from 5.0 to 9.0, which indicates that Ca-modified WRS is a promising material for various applications. The methane-production and chemical oxygen demand-removal aspects of anaerobic digestion were much improved with the addition of Ca-modified WRS. Therefore, Ca-modified WRS could be developed into a viable ammonium adsorbent for the anaerobic digestion of ammonium-rich wastes. PMID:23837319

  13. Pig slurry concentration by vacuum evaporation: influence of previous mesophilic anaerobic digestion process.

    PubMed

    Bonmatí, August; Flotats, Xavier

    2003-01-01

    Water can be removed from pig slurry by evaporation, through the application of wasted heat from a power plant or from other processes. Apart from obtaining a concentrate with an obviously higher nutrient concentration than the original slurry, another objective of water removal is to obtain water as condensate, which could be reused. The objective of this work was to study the vacuum evaporation of pig slurry liquid fraction and to evaluate condensate composition as a function of both pH (4, 5, and 6) and pig slurry type (fresh slurry and anaerobically digested slurry). Batch experiments showed that condensate characteristics, total ammonia nitrogen (NH3-N), volatile fatty acids (VFA), and chemical oxygen demand were strongly dependent on initial slurry pH. In addition to producing part of the required thermal energy, previous anaerobic digestion presented several other clear advantages. The consumption of VFA and other volatile organic compounds during anaerobic digestion reduced the volatilization of organic matter in the evaporation treatment and, consequently, provided a higher quality condensate.

  14. [Pilot study of thermal treatment/thermophilic anaerobic digestion process treating waste activated sludge of high solid content].

    PubMed

    Wu, Jing; Wang, Guang-qi; Cao, Zhi-ping; Li, Zhong-hua; Hu, Yu-ying; Wang, Kai-jun; Zu, Jian-e

    2014-09-01

    A pilot-scale experiment about the process of "thermal pretreatment at 70°C/thermophilic anaerobic digestion" of waste activated sludge of high solid content (8% -9% ) was conducted. The process employed thermal treatment of 3 days to accelerate the hydrolysis and thermophilic digestion to enhance anaerobic reaction. Thus it was good at organic removal and stabilization. When the solid retention time (SRT) was longer than 20 days, the VSS removal rate was greater than 42. 22% and it was linearly correlated to the SRT of the aerobic digestion with the R2 of 0. 915 3. It was suggested that SRT of anaerobic digestion was 25 days in practice. VSS removal rate and biogas production rate of the pilot experiment were similar to those of the run-well traditional full-scale sludge anaerobic digestion plants (solid content 3% -5% ) and the plant of high solid content using German technique.

  15. The investigation of the sludge reduction efficiency and mechanisms in oxic-settling-anaerobic (OSA) process.

    PubMed

    Demir, Özlem; Filibeli, Ayşe

    2016-01-01

    This paper aims to provide a full understanding of the sludge reduction mechanisms in the oxic-settling-anaerobic (OSA) process and presents an evaluation of the sludge reduction efficiencies and sludge characteristics in this process compared to the conventional activated sludge process. Fifty-eight percent reduction in observed yield in the OSA process was achieved compared to the control system at the end of the operational period with no deterioration of effluent quality. The settleability of sludge in the OSA process was also found to be better than that of the control system in terms of sludge volume index. In long-term operation, capillary suction time and specific resistance to filtration values confirmed that the OSA process showed good filterability characteristics. The results of batch experiments showed that higher endogenous respiration in the systems might lead to lower sludge production and that energy uncoupling had only a limited impact on sludge reduction. PMID:27191551

  16. Bioaugmentation of anaerobic sludge digestion with iron-reducing bacteria: process and microbial responses to variations in hydraulic retention time.

    PubMed

    Baek, Gahyun; Kim, Jaai; Shin, Seung Gu; Lee, Changsoo

    2016-01-01

    Although anaerobic digestion (AD) is a widely used option to manage waste activated sludge (WAS), there are some drawbacks related to its slow reaction rate and low energy productivity. This study examined an anaerobic WAS digester, augmented with an iron-reducing microbial consortium, relative to changes in microbial community structure and process performance at decreasing hydraulic retention times (HRTs) of 20 to 10 days. The enhanced methanation performance (approximately 40 % increase in methane yield) by the bioaugmentation was sustained until the HRT was decreased to 12.5 days, under Fe(3+)-rich conditions (ferric oxyhydroxide, 20 mM Fe). Enhanced iron-reducing activity was evidenced by the increased Fe(2+) to total Fe ratio maintained above 50 % during the stable operational phases. A further decrease in HRT to 10 days resulted in a significant performance deterioration, along with a drop in the Fe(2+) to total Fe ratio to <35 %, after four turnovers of operation. Prevailing existence of putative iron-reducing bacteria (IRBs) was identified by denaturing gradient gel electrophoresis (DGGE), with Spirochaetaceae- and Thauera-related organisms being dominant members, and clear dominance shifts among them with respect to decrease in HRT were observed. Lowering HRT led to evident shifts in bacterial community structure likely associated with washout of IRBs, leading to decreases in iron respiration activity and AD performance at a lower HRT. The bacterial community structure shifted dynamically over phases, and the community transitions correlated well with the changes in process performance. Overall, the combined biostimulation and bioaugmentation investigated in this study proved effective for enhanced methane recovery from anaerobic WAS digestion, which suggests an interesting potential for high-rate AD.

  17. Anaerobic processes in waste treatment: Methane production. (Latest citations from the Life Sciences Collection data base). Published Search

    SciTech Connect

    Not Available

    1992-10-01

    The bibliography contains citations concerning research, development, and applications of methane gas production by anaerobic conversion of waste materials, primarily agricultural and animal wastes, but including refuse and sewage wastes. Articles discuss the anaerobic processes involved in waste digestion, the microorganisms responsible for bioconversion of wastes, environmental variables and toxins, and energy production using biogas generators. Both large and small scale systems are considered. (Contains 250 citations and includes a subject term index and title list.)

  18. Effect of sulfate on low-temperature anaerobic digestion

    PubMed Central

    Madden, Pádhraig; Al-Raei, Abdul M.; Enright, Anne M.; Chinalia, Fabio A.; de Beer, Dirk; O'Flaherty, Vincent; Collins, Gavin

    2014-01-01

    The effect of sulfate addition on the stability of, and microbial community behavior in, low-temperature anaerobic expanded granular sludge bed-based bioreactors was investigated at 15°C. Efficient bioreactor performance was observed, with chemical oxygen demand (COD) removal efficiencies of >90%, and a mean SO2−4 removal rate of 98.3%. In situ methanogensis appeared unaffected at a COD: SO2−4 influent ratio of 8:1, and subsequently of 3:1, and was impacted marginally only when the COD: SO2−4 ratio was 1:2. Specific methanogenic activity assays indicated a complex set of interactions between sulfate-reducing bacteria (SRB), methanogens and homoacetogenic bacteria. SO2−4 addition resulted in predominantly acetoclastic, rather than hydrogenotrophic, methanogenesis until >600 days of SO2−4-influenced bioreactor operation. Temporal microbial community development was monitored by denaturation gradient gel electrophoresis (DGGE) of 16S rRNA genes. Fluorescence in situ hybridizations (FISH), qPCR and microsensor analysis were combined to investigate the distribution of microbial groups, and particularly SRB and methanogens, along the structure of granular biofilms. qPCR data indicated that sulfidogenic genes were present in methanogenic and sulfidogenic biofilms, indicating the potential for sulfate reduction even in bioreactors not exposed to SO2−4. Although the architecture of methanogenic and sulfidogenic granules was similar, indicating the presence of SRB even in methanogenic systems, FISH with rRNA targets found that the SRB were more abundant in the sulfidogenic biofilms. Methanosaeta species were the predominant, keystone members of the archaeal community, with the complete absence of the Methanosarcina species in the experimental bioreactor by trial conclusion. Microsensor data suggested the ordered distribution of sulfate reduction and sulfide accumulation, even in methanogenic granules. PMID:25120534

  19. EFFECT OF BTEX AND ETHANOL ON ANAEROBIC BIOTRANSFORMATION OF MTBE

    EPA Science Inventory

    We have recently demonstrated that natural anaerobic biotransformation of MTBE to TBA can account for the natural attenuation of MTBE in a plume from a gasoline spill at Parsippany, New Jersey. It is well established in the literature that the presence of the BTEX compounds natu...

  20. Effects of substrates on N2O emissions in an anaerobic ammonium oxidation (anammox) reactor.

    PubMed

    Jin, Yue; Wang, Dunqiu; Zhang, Wenjie

    2016-01-01

    N2O emission in the anaerobic ammonium oxidation (anammox) process is of growing concern. In this study, effects of substrate concentrations on N2O emissions were investigated in an anammox reactor. Extremely high N2O emissions of 1.67 % were led by high NH4-N concentrations. Results showed that N2O emissions have a positive correlation with NH4-N concentrations in the anammox reactor. Reducing NH4-N concentrations by recycling pump resulted in decreasing N2O emissions. In addition, further studies were performed to identify a key biological process that is contributed to N2O emissions from the anammox reactor. Based on the results obtained, Nitrosomonas, which can oxidize ammonia to nitrite, was deemed as the main sources of N2O emissions. PMID:27376009

  1. Effects of household detergent on anaerobic fermentation of kitchen wastewater from food waste disposer.

    PubMed

    Lee, K H; Park, K Y; Khanal, S K; Lee, J W

    2013-01-15

    This study examines the effects of household detergent on anaerobic methane fermentation of wastewater from food waste disposers (FWDs). Anaerobic toxicity assay (ATA) demonstrated that methane production substantially decreased at a higher detergent concentration. The Gompertz three-parameter model fitted well with the ATA results, and both the extent of methane production (M) and methane production rate (R(m)) obtained from the model were strongly affected by the concentration of the detergent. The 50% inhibitory concentration (IC(50)) of the detergent was 603 mg/L based on R(m). Results from fatty acid methyl esters (FAMEs) analysis of microbial culture revealed that deterioration of methane fermentation was attributed to impaired structure of anaerobic microbial membrane due to detergent. This study suggests that wastewater from FWD could be used for methane production, but it is necessary to reduce the concentration of detergent prior to anaerobic fermentation.

  2. Biogas production and methanogenic archaeal community in mesophilic and thermophilic anaerobic co-digestion processes.

    PubMed

    Yu, D; Kurola, J M; Lähde, K; Kymäläinen, M; Sinkkonen, A; Romantschuk, M

    2014-10-01

    Over 258 Mt of solid waste are generated annually in Europe, a large fraction of which is biowaste. Sewage sludge is another major waste fraction. In this study, biowaste and sewage sludge were co-digested in an anaerobic digestion reactor (30% and 70% of total wet weight, respectively). The purpose was to investigate the biogas production and methanogenic archaeal community composition in the anaerobic digestion reactor under meso- (35-37 °C) and thermophilic (55-57 °C) processes and an increasing organic loading rate (OLR, 1-10 kg VS m(-3) d(-1)), and also to find a feasible compromise between waste treatment capacity and biogas production without causing process instability. In summary, more biogas was produced with all OLRs by the thermophilic process. Both processes showed a limited diversity of the methanogenic archaeal community which was dominated by Methanobacteriales and Methanosarcinales (e.g. Methanosarcina) in both meso- and thermophilic processes. Methanothermobacter was detected as an additional dominant genus in the thermophilic process. In addition to operating temperatures, the OLRs, the acetate concentration, and the presence of key substrates like propionate also affected the methanogenic archaeal community composition. A bacterial cell count 6.25 times higher than archaeal cell count was observed throughout the thermophilic process, while the cell count ratio varied between 0.2 and 8.5 in the mesophilic process. This suggests that the thermophilic process is more stable, but also that the relative abundance between bacteria and archaea can vary without seriously affecting biogas production.

  3. Concentration of pig slurry by evaporation: anaerobic digestion as the key process.

    PubMed

    Bonmatí, A; Campos, E; Flotats, X

    2003-01-01

    Nutrient redistribution between areas with a structural pig slurry surplus and those with a shortage, is limited by the high cost of transportation and spreading, due to the high water content in slurry (more than 90%) and its relative low nutrient concentration. Water can be removed from slurry by evaporation, through the application of waste heat from a power plant or from other processes. Apart from obtaining a concentrate with an obviously higher nutrient concentration than the original slurry, another objective is to obtain clean water as condensate. The objective of this work was to study the batch vacuum evaporation of pig slurry liquid fraction, to evaluate the economic feasibility and to evaluate condensate quality as a function of both pH (4, 5 and 6) and pig slurry type (fresh slurry and anaerobically digested slurry). Results showed that condensate characteristics (ammonia nitrogen, VFA, COD) were strongly dependent on these variables. Previous anaerobic digestion presented clear advantages: it provided a fraction of the required energy and it removed organic matter, preventing its volatilisation in the evaporation process and providing higher quality condensates. These advantages make the combined treatment strategy economically more feasible than the evaporation process alone.

  4. Activated zeolite--suitable carriers for microorganisms in anaerobic digestion processes?

    PubMed

    Weiß, S; Lebuhn, M; Andrade, D; Zankel, A; Cardinale, M; Birner-Gruenberger, R; Somitsch, W; Ueberbacher, B J; Guebitz, G M

    2013-04-01

    Plant cell wall structures represent a barrier in the biodegradation process to produce biogas for combustion and energy production. Consequently, approaches concerning a more efficient de-polymerisation of cellulose and hemicellulose to monomeric sugars are required. Here, we show that natural activated zeolites (i.e. trace metal activated zeolites) represent eminently suitable mineral microhabitats and potential carriers for immobilisation of microorganisms responsible for anaerobic hydrolysis of biopolymers stabilising related bacterial and methanogenic communities. A strategy for comprehensive analysis of immobilised anaerobic populations was developed that includes the visualisation of biofilm formation via scanning electron microscopy and confocal laser scanning microscopy, community and fingerprint analysis as well as enzyme activity and identification analyses. Using SDS polyacrylamide gel electrophoresis, hydrolytical active protein bands were traced by congo red staining. Liquid chromatography/mass spectroscopy revealed cellulolytical endo- and exoglucanase (exocellobiohydrolase) as well as hemicellulolytical xylanase/mannase after proteolytic digestion. Relations to hydrolytic/fermentative zeolite colonisers were obtained by using single-strand conformation polymorphism analysis (SSCP) based on amplification of bacterial and archaeal 16S rRNA fragments. Thereby, dominant colonisers were affiliated to the genera Clostridium, Pseudomonas and Methanoculleus. The specific immobilisation on natural zeolites with functional microbes already colonising naturally during the fermentation offers a strategy to systematically supply the biogas formation process responsive to population dynamics and process requirements. PMID:23435898

  5. [Modeling and dynamic simulation of the multimode anaerobic/anoxic/aerobic wastewater treatment process].

    PubMed

    Zhou, Zhen; Wu, Zhi-Chao; Wang, Zhi-Wei; Du, Xing-Zhi; Jiang, Ling-Yan; Xing, Can

    2013-04-01

    Mathematical modeling is a useful tool for professional education, process development, design evaluation, operational optimization and automatic control of the wastewater treatment system, and has been extensively applied in numerous full-scale wastewater treatment plants. The ASM2d model was calibrated by the process data, and used to simulate 15 operational test runs of the multimode anaerobic/anoxic/aerobic (AAO) process. After calibration, the model was capable of simulating the sludge concentrations and effluent data in 15 test runs of the multimode AAO system. The dynamic simulation results showed an overall good agreement between the measured and simulated data, for both effluent data and sludge concentrations, with a good reproduction of dynamic processes in AO test runs. PMID:23798127

  6. Growth of Chlorella vulgaris on sugarcane vinasse: the effect of anaerobic digestion pretreatment.

    PubMed

    Marques, Sheyla Santa Isabel; Nascimento, Iracema Andrade; de Almeida, Paulo Fernando; Chinalia, Fábio Alexandre

    2013-12-01

    Microalgae farming has been identified as the most eco-sustainable solution for producing biodiesel. However, the operation of full-scale plants is still limited by costs and the utilization of industrial and/or domestic wastes can significantly improve economic profits. Several waste effluents are valuable sources of nutrients for the cultivation of microalgae. Ethanol production from sugarcane, for instance, generates significant amounts of organically rich effluent, the vinasse. After anaerobic digestion treatment, nutrient remaining in such an effluent can be used to grow microalgae. This research aimed to testing the potential of the anaerobic treated vinasse as an alternative source of nutrients for culturing microalgae with the goal of supplying the biodiesel industrial chain with algal biomass and oil. The anaerobic process treating vinasse reached a steady state at about 17 batch cycles of 24 h producing about 0.116 m(3)CH4 kgCODvinasse (-1). The highest productivity of Chlorella vulgaris biomass (70 mg l(-1) day(-1)) was observed when using medium prepared with the anaerobic digester effluent. Lipid productivity varied from 0.5 to 17 mg l(-1) day(-1). Thus, the results show that it is possible to integrate the culturing of microalgae with the sugarcane industry by means of anaerobic digestion of the vinasse. There is also the advantageous possibility of using by-products of the anaerobic digestion such as methane and CO2 for sustaining the system with energy and carbon source, respectively. PMID:24013860

  7. Effects of lipid concentration on anaerobic co-digestion of municipal biomass wastes.

    PubMed

    Sun, Yifei; Wang, Dian; Yan, Jiao; Qiao, Wei; Wang, Wei; Zhu, Tianle

    2014-06-01

    The influence of the lipid concentration on the anaerobic co-digestion of municipal biomass waste and waste-activated sludge was assessed by biochemical methane potential (BMP) tests and by bench-scale tests in a mesophilic semi-continuous stirred tank reactor. The effect of increasing the volatile solid (VS) concentration of lipid from 0% to 75% was investigated. BMP tests showed that lipids in municipal biomass waste could enhance the methane production. The results of bench-scale tests showed that a lipids concentration of 65% of total VS was the inhibition concentration. Methane yields increased with increasing lipid concentration when lipid concentrations were below 60%, but when lipid concentration was set as 65% or higher, methane yields decreased sharply. When lipid concentrations were below 60%, the pH values were in the optimum range for the growth of methanogenic bacteria and the ratios of volatile fatty acid (VFA)/alkalinity were in the range of 0.2-0.6. When lipid concentrations exceeded 65%, the pH values were below 5.2, the reactor was acidized and the values of VFA/alkalinity rose to 2.0. The amount of Brevibacterium decreased with increasing lipid content. Long chain fatty acids stacked on the methanogenic bacteria and blocked the mass transfer process, thereby inhibiting anaerobic digestion.

  8. Enhanced anaerobic digestion of piggery wastewater by ammonia stripping: effects of alkali types.

    PubMed

    Zhang, Lei; Jahng, Deokjin

    2010-10-15

    Air stripping at alkaline pH was carried out to remove ammonia from the piggery wastewater, and its effects on subsequent anaerobic digestion were investigated in semi-continuous experiments. In ammonia stripping process, three alkalis (NaOH, KOH and CaO) were used for pH adjustment. When using NaOH and KOH, the methane production rate increased more than two folds as compared to the control (no ammonia stripped), but cation toxicity exerted by sodium and potassium ions was observed. When using lime, on the contrary, it was found that volumetric methane production rates (1040-1130 mL CH(4)/L day) and yields (262.3-258.9 mL CH(4)/g of COD(added)) were significantly higher than others. In addition, the organic removal efficiencies (54.2-59.5% of volatile solid, 59.6-64.0% of total COD, 72.1-81.9% of soluble COD and 89.3-98.9% of volatile fatty acid) were also high. Batch toxicity test results confirmed that cations of Na(+), K(+) were strong methanogenic inhibitors as compared to Ca(2+). From these observations, it was concluded that ammonia stripping at alkaline pH is important for anaerobic digestion of piggery wastewater and the alkali types should be chosen cautiously to avoid cation toxicity.

  9. Nitrate reduction pathway in an anaerobic acidification reactor and its effect on acid fermentation.

    PubMed

    Xie, Li; Ji, Chi; Wang, Rui; Zhou, Qi

    2015-01-01

    This study investigated the performance of a reactor in which denitrification was integrated into the anaerobic acidogenic process. Industrial wastewater cassava stillage was used as the carbon source, and the nitrate reduction pathway and its effects on acid fermentation were examined. Results from batch and semi-continuous tests showed that the presence of nitrate did not inhibit anaerobic acidification but altered the distribution of volatile fatty acid (VFA) species. Nitrate reduction was attributable to denitrification and to dissimilatory nitrate reduction to ammonia (DNRA). The ratio of DNRA to denitrification was proportional to the ratio of [Formula: see text] . After 130 days of semi-continuous operation, denitrification removal efficiency accounted for about 60% at a [Formula: see text] of 50. The proportional distribution of VFAs was acetate, followed by propionate and then butyrate. The polymerase chain reaction-denaturing gradient gel electrophoresis results confirmed the contributions of denitrification and DNRA in the nitrate-amended reactor and showed that the addition of nitrate enriched the structure of the bacterial community, but did not suppress the activity of acid-producing bacteria. PMID:24986524

  10. Mathematical modeling of the effects of aerobic and anaerobic chelate bioegradation on actinide speciation.

    SciTech Connect

    Banaszak, J.E.; VanBriesen, J.; Rittmann, B.E.; Reed, D.T.

    1998-03-19

    Biodegradation of natural and anthropogenic chelating agents directly and indirectly affects the speciation, and, hence, the mobility of actinides in subsurface environments. We combined mathematical modeling with laboratory experimentation to investigate the effects of aerobic and anaerobic chelate biodegradation on actinide [Np(IV/V), Pu(IV)] speciation. Under aerobic conditions, nitrilotriacetic acid (NTA) biodegradation rates were strongly influenced by the actinide concentration. Actinide-chelate complexation reduced the relative abundance of available growth substrate in solution and actinide species present or released during chelate degradation were toxic to the organisms. Aerobic bio-utilization of the chelates as electron-donor substrates directly affected actinide speciation by releasing the radionuclides from complexed form into solution, where their fate was controlled by inorganic ligands in the system. Actinide speciation was also indirectly affected by pH changes caused by organic biodegradation. The two concurrent processes of organic biodegradation and actinide aqueous chemistry were accurately linked and described using CCBATCH, a computer model developed at Northwestern University to investigate the dynamics of coupled biological and chemical reactions in mixed waste subsurface environments. CCBATCH was then used to simulate the fate of Np during anaerobic citrate biodegradation. The modeling studies suggested that, under some conditions, chelate degradation can increase Np(IV) solubility due to carbonate complexation in closed aqueous systems.

  11. Nitrate reduction pathway in an anaerobic acidification reactor and its effect on acid fermentation.

    PubMed

    Xie, Li; Ji, Chi; Wang, Rui; Zhou, Qi

    2015-01-01

    This study investigated the performance of a reactor in which denitrification was integrated into the anaerobic acidogenic process. Industrial wastewater cassava stillage was used as the carbon source, and the nitrate reduction pathway and its effects on acid fermentation were examined. Results from batch and semi-continuous tests showed that the presence of nitrate did not inhibit anaerobic acidification but altered the distribution of volatile fatty acid (VFA) species. Nitrate reduction was attributable to denitrification and to dissimilatory nitrate reduction to ammonia (DNRA). The ratio of DNRA to denitrification was proportional to the ratio of [Formula: see text] . After 130 days of semi-continuous operation, denitrification removal efficiency accounted for about 60% at a [Formula: see text] of 50. The proportional distribution of VFAs was acetate, followed by propionate and then butyrate. The polymerase chain reaction-denaturing gradient gel electrophoresis results confirmed the contributions of denitrification and DNRA in the nitrate-amended reactor and showed that the addition of nitrate enriched the structure of the bacterial community, but did not suppress the activity of acid-producing bacteria.

  12. Anaerobic digestion of poplar processing residues for methane production after alkaline treatment.

    PubMed

    Yao, Yiqing; He, Mulan; Ren, Yubing; Ma, Liying; Luo, Yang; Sheng, Hongmei; Xiang, Yun; Zhang, Hua; Li, Qien; An, Lizhe

    2013-04-01

    Poplar processing residues were used for methane production by anaerobic digestion after alkaline treatment and methane production was measured. The highest methane production of 271.9 L/kg volatile solid (VS) was obtained at conditions of 35 g/L and 5.0% NaOH, which was 113.8% higher than non-alkaline treated samples, and 28.9% higher than that of corn straw, which is the conventional anaerobic digestion material in China. The maximal enhancement of 275.5% obtained at conditions of 50 g/L and 7.0% NaOH. Degradation of cellulose, hemicellulose and lignin after treatment increased by 4.0-9.0%, 3.3-6.2%, and 11.1-20.5%, respectively, with NaOH dose ranged from 3.0% to 7.0%. Scanning electron microscopy (SEM), FTIR spectra and Crystallinity measurements showed that the lignocellulosic structures were disrupted by NaOH. The results indicate poplar processing residues might be an efficient substrate for methane production after alkaline treatment.

  13. Anaerobic digestion of waste activated sludge pretreated by a combined ultrasound and chemical process.

    PubMed

    Seng, Bunrith; Khanal, Samir Kumar; Visvanathan, Chettiyappan

    2010-03-01

    Waste activated sludge (WAS) requires a long digestion time because of a rate-limiting hydrolysis step - the first phase of anaerobic digestion. Pretreatment of WAS facilitates the hydrolysis step and improves the digestibility. This study examined the effects of ultrasonic, chemical, and combined chemical-ultrasonic pretreatments on WAS disintegration and its subsequent digestion at different solids retention times (SRTs). The efficient conditions for each pretreatment were evaluated based on per cent soluble chemical oxygen demand (%SCOD). The results showed that the combined chemical-ultrasonic pretreatment resulted in better WAS disintegration, based on %SCOD release, compared with individual chemical and ultrasonic pretreatments. At the optimum operating conditions of the combined chemical-ultrasonic pretreatment (NaOH dose of 10 mg g(-1) TS (total solids) and specific energy input of 3.8 kJ g(-1)TS), the %SCOD release was 18.1% +/- 0.5%, whereas 13.5% +/- 0.9%, 13.0% +/- 0.5% and 1.1% +/- 0.1% corresponded to individual chemical (50 mg g(-1) TS) and ultrasonic (3.8 kJ g(-1) TS) pretreatments and control (without pretreatment), respectively. The anaerobic digestion studies in continuous stirred tank reactors showed an increase in methane production of 23.4% +/- 1.3% and 31.1 +/- 1.2% for digesters fed with WAS pretreated with ultrasonic and combined chemical-ultrasonic, respectively, with respect to controls at the effective SRT of 15 days. The highest total solids removal was achieved in the digester fed with ultrasonic pretreated WAS (16.6% +/- 0.3%), whereas the highest volatile solids removal was achieved from the digester fed with combined chemical-ultrasonic pretreated WAS (24.8 +/- 0.4%). The findings from this study are a useful contribution to new pretreatment techniques in the field of sludge treatment technology through anaerobic digestion.

  14. Enhanced coproduction of hydrogen and methane from cornstalks by a three-stage anaerobic fermentation process integrated with alkaline hydrolysis.

    PubMed

    Cheng, Xi-Yu; Liu, Chun-Zhao

    2012-01-01

    A three-stage anaerobic fermentation process including H(2) fermentation I, H(2) fermentation II, methane fermentation was developed for the coproduction of hydrogen and methane from cornstalks. Hydrogen production from cornstalks using direct microbial conversion by Clostridium thermocellum 7072 was markedly enhanced in the two-stage thermophilic hydrogen fermentation process integrated with alkaline treatment. The highest total hydrogen yield from cornstalks in the two-stage fermentation process reached 74.4 mL/g-cornstalk. The hydrogen fermentation effluents and alkaline hydrolyzate were further used for methane fermentation by anaerobic granular sludge, and the total methane yield reached 205.8 mL/g-cornstalk. The total energy recovery in the three-stage anaerobic fermentation process integrated with alkaline hydrolysis reached 70.0%.

  15. Central treatment of different emulsion wastewaters by an integrated process of physicochemically enhanced ultrafiltration and anaerobic-aerobic biofilm reactor.

    PubMed

    Zhang, Weijun; Xiao, Ping; Wang, Dongsheng

    2014-05-01

    The feasibility of an integrated process of ultrafiltration (UF) enhanced by combined chemical emulsion breaking with vibratory shear and anaerobic/aerobic biofilm reactor for central treatment of different emulsion wastewaters was investigated. Firstly, it was found that calcium chloride exhibited better performance in oil removal than other inorganic salts. Chemical demulsification pretreatment could efficiently improve oil removal and membrane filtration in emulsion wastewater treatment by VSEP. According to aerobic batch bioassay, UF permeate exhibited good biodegradability and could be further treated with biological process. Additionally, pilot test indicated that anaerobic-aerobic biofilm exhibited an excellent ability against rise in organic loading and overall chemical oxygen demand (COD) removal efficiency of biological system was more than 93% of which 82% corresponded to the anaerobic process and 11% to the aerobic degradation. The final effluent of integrated process could meet the "water quality standards for discharge to municipal sewers" in China.

  16. Bioenergy from anaerobically treated wastewater

    SciTech Connect

    Richards, E.A.

    1981-01-01

    Breweries and other processing plants including dairy cooperatives, sugar plants, grain mills, gasohol plants, etc., produce wastewater containing complex organic matter, either in solution or as volatile suspended solids, which can be treated anaerobically to effectively reduce the pollutants by 85-95% and generate a CH4 containing gas. An example anaerobic plant to serve a 10 to the power of 6-bbl brewery is discussed.

  17. Dynamic evaluation of a fixed bed anaerobic digestion process in response to organic overloads and toxicant shock loads.

    PubMed

    Dupla, M; Conte, T; Bouvier, J C; Bernet, N; Steyer, J P

    2004-01-01

    This paper details a dynamic evaluation of a 1 m3 fixed bed anaerobic digestion reactor in response to organic overloads and toxicant shock loads. Raw industrial wine distillery wastewater was used as a reference substrate and several disturbances were applied to the process: (i) organic overloads with and without pH regulation in the feeding line, (ii) adding of ammonia in the input wastewater. The purpose of this study was to assess, using on-line instrumentation, the robustness of a fixed bed anaerobic digester. Anaerobic digestion processes have the reputation of being difficult to operate and prone to process instability due to external disturbances and the objective of this study was to demonstrate the possibility of such a reactor configuration for industrial use.

  18. Liquid-to-Gas Mass Transfer in Anaerobic Processes: Inevitable Transfer Limitations of Methane and Hydrogen in the Biomethanation Process

    PubMed Central

    Pauss, André; Andre, Gérald; Perrier, Michel; Guiot, Serge R.

    1990-01-01

    Liquid-to-gas mass transfer in anaerobic processes was investigated theoretically and experimentally. By using the classical definition of kLa, the global volumetric mass transfer coefficient, theoretical development of mass balances in such processes demonstrates that the mass transfer of highly soluble gases is not limited in the usual conditions occurring in anaerobic fermentors (low-intensity mixing). Conversely, the limitation is important for poorly soluble gases, such as methane and hydrogen. The latter could be overconcentrated to as much as 80 times the value at thermodynamic equilibrium. Such overconcentrations bring into question the biological interpretations that have been deduced solely from gaseous measurements. Experimental results obtained in three different methanogenic reactors for a wide range of conditions of mixing and gas production confirmed the general existence of low mass transfer coefficients and consequently of large overconcentrations of dissolved methane and hydrogen (up to 12 and 70 times the equilibrium values, respectively). Hydrogen mass transfer coefficients were obtained from the direct measurements of dissolved and gaseous concentrations, while carbon dioxide coefficients were calculated from gas phase composition and calculation of related dissolved concentration. Methane transfer coefficients were based on calculations from the carbon dioxide coefficients. From mass balances performed on a gas bubble during its simulated growth and ascent to the surface of the liquid, the methane and carbon dioxide contents in the gas bubble appeared to be controlled by the bubble growth process, while the bubble ascent was largely responsible for a slight enrichment in hydrogen. PMID:16348206

  19. Synthetic effect between iron oxide and sulfate mineral on the anaerobic transformation of organic substance.

    PubMed

    Chen, Tian-Hu; Wang, Jin; Zhou, Yue-Fei; Yue, Zheng-Bo; Xie, Qiao-Qin; Pan, Min

    2014-01-01

    Synthetic effect between sulfate minerals (gypsum) and iron oxide (hematite) on the anaerobic transformation of organic substance was investigated in the current study. The results showed that gypsum was completely decomposed while hematite was partially reduced. The mineral phase analysis results showed that FeS and CaCO3 was the major mineralization product. Methane generation process was inhibited and inorganic carbon contents in the precipitates were enhanced compared to the control without hematite and gypsum. The inorganic carbon content increased with the increasing of hematite dosages. Co-addition of sulfate minerals and iron oxide would have a potential application prospect in the carbon sequestration area and reduction of the greenhouse gas release. The results would also reveal the role of inorganic mineral in the global carbon cycle. PMID:24189378

  20. [Study on the start-up of anaerobic ammonium oxidation process in biological activated carbon reactor].

    PubMed

    Lai, Wei-Yi; Zhou, Wei-Li; He, Sheng-Bing

    2013-08-01

    In order to shorten the start-up time of anaerobic ammonium oxidation (ANAMMOX) reactor, biological activated cabon reactor was applied. Three lab scale UASB reactors were seeded with anaerobic sludge, fed with synthetic wastewater containing ammonia and nitrite, and supplemented with granular activated carbon on day 0, 33 and 56, respectively. The nitrogen removal performance of the first reactor, into which GAC was added on day 0, showed no significant improvement in 90 days. After being suspended for about one month, the secondary start-up of this reactor succeeded in another 33 days (totally 123 days). 49 d and 85 d were taken for the other two reactors started up by the addition of GAC on day 33 and 56, respectively. After the reactors were started up, the average removal rates of total nitrogen were 89.8%, 86.7% and 86.7%, respectively. The start-up process could be divided into four stages, namely, the bacterial autolysis phase, the lag phase, the improve phase and the stationary phase, and the best time for adding GAC carrier was right after the start of the lag phase.

  1. Comparison of static, in-vessel composting of MSW with thermophilic anaerobic digestion and combinations of the two processes.

    PubMed

    Walker, Lee; Charles, Wipa; Cord-Ruwisch, Ralf

    2009-08-01

    The biological stabilisation of the organic fraction of municipal solid waste (OFMSW) into a form stable enough for land application can be achieved via aerobic or anaerobic treatments. To investigate the rates of degradation (e.g. via electron equivalents removed, or via carbon emitted) of aerobic and anaerobic treatment, OFMSW samples were exposed to computer controlled laboratory-scale aerobic (static in-vessel composting), and anaerobic (thermophilic anaerobic digestion with liquor recycle) treatment individually and in combination. A comparison of the degradation rates, based on electron flow revealed that provided a suitable inoculum was used, anaerobic digestion was the faster of the two waste conversion process. In addition to faster maximum substrate oxidation rates, anaerobic digestion (followed by post-treatment aerobic maturation), when compared to static composting alone, converted a larger fraction of the organics to gaseous end-products (CO2 and CH4), leading to improved end-product stability and maturity, as measured by compost self-heating and root elongation tests, respectively. While not comparable to windrow and other mixed, highly aerated compost systems, our results show that in the thermophilic, in-vessel treatment investigated here, the inclusion of a anaerobic phase, rather than using composting alone, improved hydrolysis rates as well as oxidation rates and product stability. The combination of the two methods, as used in the DiCOM process, was also tested allowing heat generation to thermophilic operating temperature, biogas recovery and a low odour stable end-product within 19 days of operation. PMID:19345576

  2. Anaerobic Digestion and its Applications

    EPA Science Inventory

    Anaerobic digestion is a natural biological process. The initials "AD" may refer to the process of anaerobic digestion, or the built systems of anaerobic digesters. While there are many kinds of digesters, the biology is basically the same for all. Anaerobic digesters are built...

  3. Deterministic processes guide long-term synchronised population dynamics in replicate anaerobic digesters

    PubMed Central

    Vanwonterghem, Inka; Jensen, Paul D; Dennis, Paul G; Hugenholtz, Philip; Rabaey, Korneel; Tyson, Gene W

    2014-01-01

    A replicate long-term experiment was conducted using anaerobic digestion (AD) as a model process to determine the relative role of niche and neutral theory on microbial community assembly, and to link community dynamics to system performance. AD is performed by a complex network of microorganisms and process stability relies entirely on the synergistic interactions between populations belonging to different functional guilds. In this study, three independent replicate anaerobic digesters were seeded with the same diverse inoculum, supplied with a model substrate, α-cellulose, and operated for 362 days at a 10-day hydraulic residence time under mesophilic conditions. Selective pressure imposed by the operational conditions and model substrate caused large reproducible changes in community composition including an overall decrease in richness in the first month of operation, followed by synchronised population dynamics that correlated with changes in reactor performance. This included the synchronised emergence and decline of distinct Ruminococcus phylotypes at day 148, and emergence of a Clostridium and Methanosaeta phylotype at day 178, when performance became stable in all reactors. These data suggest that many dynamic functional niches are predictably filled by phylogenetically coherent populations over long time scales. Neutral theory would predict that a complex community with a high degree of recognised functional redundancy would lead to stochastic changes in populations and community divergence over time. We conclude that deterministic processes may play a larger role in microbial community dynamics than currently appreciated, and under controlled conditions it may be possible to reliably predict community structural and functional changes over time. PMID:24739627

  4. Effect of anaerobic digestion on oocysts of the protozoan Eimeria tenella.

    PubMed Central

    Lee, M R; Shih, J C

    1988-01-01

    The effect of anaerobic digestion of poultry waste on oocysts of the protozoan Eimeria tenella, a common enteric pathogen that causes coccidiosis in poultry, was investigated in this study. Thermophilic (50 degrees C) and mesophilic (35 degrees C) anaerobic digestors, with poultry manure as the substrate, were inoculated with the oocysts. The oocysts were damaged during anaerobic digestion, as determined by morphological change and loss of their ability to sporulate. The recovered oocysts were tested for their infectivity in young chicks, as measured by body weight gain, mortality, and cecal lesions. Oocysts lost all their infectivity during thermophilic digestion, while oocysts subjected to mesophilic digestion remained moderately infective in comparison with untreated oocysts, which produced severe coccidiosis, high mortality, and low body weight gain in chicks. Oocysts were inactivated at 50 degrees C when they were suspended in digestor fluid or saline. Inactivation at 35 degrees C was significantly stronger in the digestor fluid than in the saline, which implied that factors other than temperature were involved in the lethal effect of anaerobic digestion on protozoan oocysts. In this study we demonstrated that the treatment of animal waste by anaerobic digestion, especially at a thermophilic temperature, has the benefits of pathogen control and protection of human and animal health in a farm environment. Images PMID:3202626

  5. [Effect of butachlor on CH4 emission and anaerobes in paddy soil].

    PubMed

    Zhao, Y; Mei, Q; Chen, M; Min, H

    1997-12-01

    Effects of butachlor on CH4 emission and the count of anaerobes in paddy soil or in the media were studied. The results obtained showed that CH4 emission and growth of methanogens would be greatly affected at field rates of butachlor within 2 weeks, but this adverse effects would disappear as time went on. CH4 emission and methanogenic activities would be retarded by butachlor in media for longer time. The amount of butachlor available to act upon anaerobes depended on application rate and method of application.

  6. 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

  7. Strong Pasteur effect in rabbit corneal endothelium preserves fluid transport under anaerobic conditions.

    PubMed

    Riley, M V; Winkler, B S

    1990-07-01

    1. The hydration and transparency of the mammalian cornea are maintained by a metabolically dependent fluid transport system located in the endothelial cell layer. The purpose of the study was to determine whether this pump activity is dependent upon aerobic or anaerobic metabolism. 2. The ability of the cornea, superfused in vitro with a bicarbonate-Ringer solution containing glucose and adenosine, to maintain normal hydration (thickness) when respiration is inhibited has been examined in intact and de-epithelialized preparations and correlated with glycolytic activity and cellular concentrations of ATP. 3. In respiring intact and de-epithelialized corneas thickness was maintained for periods up to 5 h during superfusion with the control Ringer solution. 4. KCN (10(-3) M) or antimycin A (10(-6) M) caused the intact cornea to swell at 15 +/- 3 microns h-1, whereas the de-epithelialized tissue maintained normal thickness under these conditions. This swelling of the intact tissue appears to be due to the osmotic effect of increased epithelial lactate production under anaerobic conditions. 5. Pre-swollen de-epithelialized corneas deturgesced fully to original thickness at a rate of 43 +/- 7 microns h-1 under aerobic conditions, but with KCN or antimycin they deturgesced at only 65% of that rate and generally failed to return to their original thickness. 6. Ouabain (10(-4) M) caused de-epithelialized corneas to swell in the presence of KCN or antimycin, as it did under aerobic conditions, showing that maintenance of hydration or deturgescence are pump-dependent processes under both conditions. 7. Lactate production was markedly stimulated by KCN or antimycin in intact and de-epithelialized preparations, but not in the stroma alone. The magnitude of the Pasteur effect was calculated to be 5-fold in the endothelium and 2.5-fold in the epithelium. Ouabain inhibited anaerobic lactate production in the endothelium by 50%. 8. ATP content of the epithelium following 5 h

  8. Influence of carbon source amendment on effectiveness of anaerobic soil disinfestation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic soil disinfestation (ASD; also termed biological soil disinfestation or soil reductive sterilization) is a non-chemical soil disinfestation process which includes 1) soil incorporation of a labile carbon (C) source, 2) mulching with a polyethylene film to limit gas exchange, and 3) drip ir...

  9. The role of paraffin oil on the interaction between denitrifying anaerobic methane oxidation and Anammox processes.

    PubMed

    Fu, Liang; Ding, Zhao-Wei; Ding, Jing; Zhang, Fang; Zeng, Raymond J

    2015-10-01

    Methane is sparingly soluble in water, resulting in a slow reaction rate in the denitrifying anaerobic methane oxidation (DAMO) process. The slow rate limits the feasibility of research to examine the interaction between the DAMO and the anaerobic ammonium oxidation (Anammox) process. In this study, optimized 5 % (v/v) paraffin oil was added as a second liquid phase to improve methane solubility in a reactor containing DAMO and Anammox microbes. After just addition, methane solubility was found to increase by 25 % and DAMO activity was enhanced. After a 100-day cultivation, the paraffin reactor showed almost two times higher consumption rates of NO3 (-) (0.2268 mmol/day) and NH4 (+) (0.1403 mmol/day), compared to the control reactor without paraffin oil. The microbes tended to distribute in the oil-water interface. The quantitative (q) PCR result showed the abundance of gene copies of DAMO archaea, DAMO bacteria, and Anammox bacteria in the paraffin reactor were higher than those in the control reactor after 1 month. Fluorescence in situ hybridization revealed that the percentages of the three microbes were 55.5 and 77.6 % in the control and paraffin reactors after 100 days, respectively. A simple model of mass balance was developed to describe the interactions between DAMO and Anammox microbes and validate the activity results. A mechanism was proposed to describe the possible way that paraffin oil enhanced DAMO activity. It is quite clear that paraffin oil enhances not only DAMO activity but also Anammox activity via the interaction between them; both NO3 (-) and NH4 (+) consumption rates were about two times those of the control.

  10. Liquefaction and methanization of solid and liquid coffee wastes by two phase anaerobic digestion process.

    PubMed

    Houbron, E; Larrinaga, A; Rustrian, E

    2003-01-01

    This study attempted to investigate the feasibility of volatile fatty acid (VFA) production from coffee pulp hydrolyse, and further to determine the potential of methanization of both the pre-acidified effluent and the coffee wastewater. The experiments were carried out in 2 completely mixed reactors, each one with a working volume of 4 litres. Coffee pulp was used as substrate in the acidogenic reactor and different mixtures of pulper and wash-water and pre-acidified effluent in the methanogenic one. The acidogenic and methanogenic reactors were operated at an organic loading rate of 5 COD g x l(-1) x d(-1) and 0.5 COD g x l(-1) x d(-1). The total, soluble and VFA's effluent COD concentrations of the acidogenic reactor present average values of 57.75, 17.00 and 13.92 g x l(-1) respectively. Under these experimental conditions, 23% (COD based) of coffee pulp was hydrolysed with a rate of 1.32 gCOD x l(-1) x d(-1) and the soluble fraction was transformed to VFA's with an acidification efficiency of 82%. Total VFA's concentration reached a value of 13.9 gCOD x l(-1), and acetate, propionate, butyrate and valerate represented 52%, 28%, 9% and 11% respectively of the liquid phase COD. In the methanogenic reactor, COD removal and methanization of fresh coffee wastewater, pre-acidified effluent and both combined occur with an efficiency of 85% to 95% respectively, with a characteristic biogas composition of 80% CH4 and 20% CO2. These results show that a humid coffee "Beneficio" processing daily 23 tons of cherry coffee (fresh fruit), equipped with a two stage anaerobic digestion process could generate at least 1,886 CH4 m3 x d(-1). This represents an increase in methane production by a factor 3 to 5 compared to a "Beneficio" using anaerobic digestion only for the treatment of its wastewater.

  11. Enhancing anaerobic digestion of waste activated sludge by pretreatment: effect of volatile to total solids.

    PubMed

    Wang, Xiao; Duan, Xu; Chen, Jianguang; Fang, Kuo; Feng, Leiyu; Yan, Yuanyuan; Zhou, Qi

    2016-01-01

    In this study the effect of volatile to total solids (VS/TS) on anaerobic digestion of waste activated sludge (WAS) pretreated by alkaline, thermal and thermal-alkaline strategies was studied. Experimental results showed that the production of methane from sludge was increased with VS/TS. When anaerobic digesters were fed with sludge pretreated by the thermal-alkaline method, the average methane yield was improved from 2.8 L/d at VS/TS 0.35 to 4.7 L/d at VS/TS 0.56. Also, the efficiency of VS reduction during sludge anaerobic digestion varied between 18.9% and 45.6%, and increased gradually with VS/TS. Mechanism investigation of VS/TS on WAS anaerobic digestion suggested that the general activities of anaerobic microorganisms, activities of key enzymes related to sludge hydrolysis, acidification and methanogenesis, and the ratio of Archaea to Bacteria were all increased with VS/TS, showing good agreement with methane production.

  12. The effect of transient loading on the performance of a mesophilic anaerobic contact reactor at constant feed strength.

    PubMed

    Sentürk, Elif; Ince, Mahir; Engin, Guleda Onkal

    2012-12-15

    Anaerobic contact reactor is a high rate anaerobic process consisting of an agitated reactor and a solids settling tank for recycling. It was proved earlier that this type of reactor design offers highly efficient performance in the conversion of organic matter to biogas. In this study, the effect of transient loading on reactor performance in terms of a number of key intermediates and parameters such as, COD removal, pH and alkalinity change, VFAs, effluent MLSS concentration and biogas efficiency over time was examined. For this purpose, a step increase of organic loading rate from 3.35kg COD/m(3)day to 15.61kg COD/m(3)day was employed. The hydraulic retention time decreased to a value of 8.42h by an increase in the influent flow-rate during the transient loading. It was observed that the mesophilic anaerobic contact reactor (MACR) was quite resistant to large transient shocks. The reactor recovered back to its baseline performance only in 15h after the shock loading was stopped. Hence, it can be concluded that this type of reactor design has a high potential in treating food processing wastewaters with varying flow characteristics.

  13. A new multiple-stage electrocoagulation process on anaerobic digestion effluent to simultaneously reclaim water and clean up biogas.

    PubMed

    Liu, Zhiguo; Stromberg, David; Liu, Xuming; Liao, Wei; Liu, Yan

    2015-03-21

    A new multiple-stage treatment process was developed via integrating electrocoagulation with biogas pumping to simultaneously reclaim anaerobic digestion effluent and clean up biogas. The 1st stage of electrocoagulation treatment under the preferred reaction condition led to removal efficiencies of 30%, 81%, 37% and >99.9% for total solids, chemical oxygen demand, total nitrogen and total phosphorus, respectively. Raw biogas was then used as a reactant and pumped into the effluent to simultaneously neutralize pH of the effluent and remove H2S in the biogas. The 2nd stage of electrocoagulation treatment on the neutralized effluent showed that under the selected reaction condition, additional 60% and 10% of turbidity and chemical oxygen demand were further removed. The study concluded a dual-purpose approach for the first time to synergistically combine biogas purification and water reclamation for anaerobic digestion system, which well addresses the downstream challenges of anaerobic digestion technology.

  14. A new multiple-stage electrocoagulation process on anaerobic digestion effluent to simultaneously reclaim water and clean up biogas.

    PubMed

    Liu, Zhiguo; Stromberg, David; Liu, Xuming; Liao, Wei; Liu, Yan

    2015-03-21

    A new multiple-stage treatment process was developed via integrating electrocoagulation with biogas pumping to simultaneously reclaim anaerobic digestion effluent and clean up biogas. The 1st stage of electrocoagulation treatment under the preferred reaction condition led to removal efficiencies of 30%, 81%, 37% and >99.9% for total solids, chemical oxygen demand, total nitrogen and total phosphorus, respectively. Raw biogas was then used as a reactant and pumped into the effluent to simultaneously neutralize pH of the effluent and remove H2S in the biogas. The 2nd stage of electrocoagulation treatment on the neutralized effluent showed that under the selected reaction condition, additional 60% and 10% of turbidity and chemical oxygen demand were further removed. The study concluded a dual-purpose approach for the first time to synergistically combine biogas purification and water reclamation for anaerobic digestion system, which well addresses the downstream challenges of anaerobic digestion technology. PMID:25540943

  15. Effects of total ammonia nitrogen concentration on solid-state anaerobic digestion of corn stover.

    PubMed

    Wang, Zhongjiang; Xu, Fuqing; Li, Yebo

    2013-09-01

    The inhibitive effect of total ammonia nitrogen (TAN) (including NH3 and NH4(+)) on solid-state anaerobic digestion of corn stover was investigated in batch reactors at 37°C. The highest methane yield of 107.0 L/kg VS(feed) was obtained at a TAN concentration of 2.5 g/kg (based on total weight). TAN concentrations greater than 2.5 g/kg resulted in decreased methane yields, with a 50% reduction observed at a concentration of 6.0 g/kg. Reduced reaction rates and microbial activities for hydrolysis of cellulose and methanogenesis from acetate were observed at TAN concentrations higher than 4.3 g/kg. Strong ammonia stress was indicated at butyrate concentrations higher than 300 mg/kg. Result showed that the effluent of liquid anaerobic digestion can provide enough nitrogen for solid-state anaerobic digestion of corn stover.

  16. Anaerobic ammonium oxidation (anammox) under realistic seasonal temperature variations: Characteristics of biogranules and process performance.

    PubMed

    Guo, Qiong; Xing, Bao-Shan; Li, Peng; Xu, Jia-Li; Yang, Chen-Chen; Jin, Ren-Cun

    2015-09-01

    In this study, the effects of realistic seasonal temperatures on the nitrogen removal performance of anaerobic ammonium oxidation (anammox) and the properties of the anammox granules were comparatively investigated for 330 days. The results demonstrated that the nitrogen removal efficiency (NRE), nitrogen loading rate (NLR) and nitrogen removal rate (NRR) were decreased dramatically, as the temperature decreased from 31.2 to 2.5 °C. However, the nitrogen removal performance recovered andante as the temperature increased gradually. After low temperature exposure, the settleability tended to worsen, and granules appeared to be more irregular with a smaller average granule diameter, and the extracellular polymeric substances (EPS) content increased slightly, while the specific anammox activity (SAA) decreased obviously. This realistic seasonal temperatures based research was an illation of the actual operation, and could be potentially implemented to maintain stability for the application of anammox technology.

  17. Color, organic matter and sulfate removal from textile effluents by anaerobic and aerobic processes.

    PubMed

    Amaral, F M; Kato, M T; Florêncio, L; Gavazza, S

    2014-07-01

    An upflow anaerobic sludge blanket (UASB)-submerged aerated biofilter (SAB) system was evaluated to remove color and chemical oxygen demand (COD) from real textile effluent. The system was operated for 335 days in three phases (P-1, P-2, P-3) with total hydraulic retention time varying from 21 h to 14 h. The results showed that high sulfate levels (>300 mg SO4(2-)/L) impaired the dye reduction. The best color removal efficiencies of 30% and 96% for the UASB and the reactor system, respectively, were obtained in P-1; the SAB higher efficiency was associated with adsorption. The best COD removal efficiency of 71% for the reactor system was obtained in P-2. Precipitation of some material composed mostly of sulfur (98%) and some metals occurred in the UASB. However, the precipitated sulfur was again oxidized in the SAB. The system also showed an effective toxicity reduction in tests (Daphnia magna) with the treated effluent.

  18. High-rate two-phase process for the anaerobic degradation of cellulose, employing rumen microorganisms for an efficient acidogenesis

    SciTech Connect

    Gijzen, H.J.; Zwart, K.B.; Verhagen, F.J.M.; Vogels, G.D.

    1988-04-05

    A novel two-stage anaerobic process for the microbial conversion of cellulose into biogas has been developed. In the first phase, a mixed population of rumen bacteria and ciliates was used in the hydrolysis and fermentation of cellulose. The volatile fatty acids (VFA) produced in this acidogenic reactor were subsequently converted into biogas in a UASB-type methanogenic reactor. A stepwise increase of the loading rate from 11.9 to 25.8 g volatile solids/L reactor volume/day (g VS/L/day) did not affect the degradation efficiency in the acidogenic reactor, whereas the methanogenic reactor appeared to be overloaded at the highest loading rate. Cellulose digestion was almost complete at all loading rates applied. The two-stage anaerobic process was also tested with a closed fluid circuit. In this instance total methane production was 0.438 L CH/sub 4//g VS added, which is equivalent to 98% of the theoretical value. The application of rumen microorganisms in combination with a high-rate methane reactor is proposed as a means of efficient anaerobic degradation of cellulosic residues to methane. Because this newly developed two-phase system is based on processes and microorganisms from the ruminant, it will be referred to as Rumen Derived Anaerobic Digestion (RUDAD)-process.

  19. A novel full recycling process through two-stage anaerobic treatment of distillery wastewater for bioethanol production from cassava.

    PubMed

    Zhang, Qing-Hua; Lu, Xin; Tang, Lei; Mao, Zhong-Gui; Zhang, Jian-Hua; Zhang, Hong-Jian; Sun, Fu-Bao

    2010-07-15

    In the present study, a novel full recycling process for bioethanol production was investigated, where three mathematical models were established to simulate the accumulation of major soluble inhibitory substances, including organic compounds, total ions, volatile fatty acids (VFAs) and colorants. These inhibitory substances in the reused water reached a relative steady state after 3-7 batches of anaerobic treatment and recycling process, which coincided with the results of mathematical models. There were no negative effects of these inhibitory substances on ethanol fermentation and the final ethanol yield, fermentation time, starch utilization ratio were very close to that of the conventional process using tap water. However, approximately 7.54% (w/w) of water was lost during each circulation, which was replenished in subsequent circulations, to assure consistent fermentation broth volume. This novel process was confirmed to have a stable operation over 13 recycles. It is concluded the stable states of the inhibitory substances in the reused water can assure this recycling process will run successfully.

  20. Identification and quantification of microbial populations in activated sludge and anaerobic digestion processes.

    PubMed

    Reyes, M; Borrás, L; Seco, A; Ferrer, J

    2015-01-01

    Eight different phenotypes were studied in an activated sludge process (AeR) and anaerobic digester (AnD) in a full-scale wastewater treatment plant by means of fluorescent in situ hybridization (FISH) and automated FISH quantification software. The phenotypes were ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, denitrifying bacteria, phosphate-accumulating organisms (PAO), glycogen-accumulating organisms (GAO), sulphate-reducing bacteria (SRB), methanotrophic bacteria and methanogenic archaea. Some findings were unexpected: (a) Presence of PAO, GAO and denitrifiers in the AeR possibly due to unexpected environmental conditions caused by oxygen deficiencies or its ability to survive aerobically; (b) presence of SRB in the AeR due to high sulphate content of wastewater intake and possibly also due to digested sludge being recycled back into the primary clarifier; (c) presence of methanogenic archaea in the AeR, which can be explained by the recirculation of digested sludge and its ability to survive periods of high oxygen levels; (d) presence of denitrifying bacteria in the AnD which cannot be fully explained because the nitrate level in the AnD was not measured. However, other authors reported the existence of denitrifiers in environments where nitrate or oxygen was not present suggesting that denitrifiers can survive in nitrate-free anaerobic environments by carrying out low-level fermentation; (e) the results of this paper are relevant because of the focus on the identification of nearly all the significant bacterial and archaeal groups of microorganisms with a known phenotype involved in the biological wastewater treatment.

  1. Evidence for anaerobic ammonium oxidation process in freshwater sediments of aquaculture ponds.

    PubMed

    Shen, Li-dong; Wu, Hong-sheng; Gao, Zhi-qiu; Ruan, Yun-jie; Xu, Xiang-hua; Li, Ji; Ma, Shi-jie; Zheng, Pei-hui

    2016-01-01

    The anaerobic ammonium oxidation (anammox) process, which can simultaneously remove ammonium and nitrite, both toxic to aquatic animals, can be very important to the aquaculture industry. Here, the presence and activity of anammox bacteria in the sediments of four different freshwater aquaculture ponds were investigated by using Illumina-based 16S rRNA gene sequencing, quantitative PCR assays and (15)N stable isotope measurements. Different genera of anammox bacteria were detected in the examined pond sediments, including Candidatus Brocadia, Candidatus Kuenenia and Candidatus Anammoxoglobus, with Candidatus Brocadia being the dominant anammox genus. Quantitative PCR of hydrazine synthase genes showed that the abundance of anammox bacteria ranged from 5.6 × 10(4) to 2.1 × 10(5) copies g(-1) sediment in the examined ponds. The potential anammox rates ranged between 3.7 and 19.4 nmol N2 g(-1) sediment day(-1), and the potential denitrification rates varied from 107.1 to 300.3 nmol N2 g(-1) sediment day(-1). The anammox process contributed 1.2-15.3% to sediment dinitrogen gas production, while the remainder would be due to denitrification. It is estimated that a total loss of 2.1-10.9 g N m(-2) per year could be attributed to the anammox process in the examined ponds, suggesting that this process could contribute to nitrogen removal in freshwater aquaculture ponds.

  2. Is anaerobic digestion effective for the removal of organic micropollutants and biological activities from sewage sludge?

    PubMed

    Gonzalez-Gil, L; Papa, M; Feretti, D; Ceretti, E; Mazzoleni, G; Steimberg, N; Pedrazzani, R; Bertanza, G; Lema, J M; Carballa, M

    2016-10-01

    The occurrence of emerging organic micropollutants (OMPs) in sewage sludge has been widely reported; nevertheless, their fate during sludge treatment remains unclear. The objective of this work was to study the fate of OMPs during mesophilic and thermophilic anaerobic digestion (AD), the most common processes used for sludge stabilization, by using raw sewage sludge without spiking OMPs. Moreover, the results of analytical chemistry were complemented with biological assays in order to verify the possible adverse effects (estrogenic and genotoxic) on the environment and human health in view of an agricultural (re)use of digested sludge. Musk fragrances (AHTN, HHCB), ibuprofen (IBP) and triclosan (TCS) were the most abundant compounds detected in sewage sludge. In general, the efficiency of the AD process was not dependent on operational parameters but compound-specific: some OMPs were highly biotransformed (e.g. sulfamethoxazole and naproxen), while others were only slightly affected (e.g. IBP and TCS) or even unaltered (e.g. AHTN and HHCB). The MCF-7 assay evidenced that estrogenicity removal was driven by temperature. The Ames test did not show point mutation in Salmonella typhimurium while the Comet test exhibited a genotoxic effect on human leukocytes attenuated by AD. This study highlights the importance of combining chemical analysis and biological activities in order to establish appropriate operational strategies for a safer disposal of sewage sludge. Actually, it was demonstrated that temperature has an insignificant effect on the disappearance of the parent compounds while it is crucial to decrease estrogenicity. PMID:27344252

  3. The Effect of Glycerol Supplements on Aerobic and Anaerobic Performance of Athletes and Sedentary Subjects

    PubMed Central

    Patlar, Suleyman; Yalçin, Hasan; Boyali, Ekrem

    2012-01-01

    The purpose of this study was to evaluate the effect of glycerol supplementation on aerobic and anaerobic exercise performance in sedentary subjects and athletes. The glycerol supplement treatments were as follows: 40 volunteers were selected and divided into two groups, sedentary and exercise groups. These two groups were further subdivided into two groups. The first group, the placebo (S), only consumed water; the second group (GS) consumed glycerol followed by water. Neither of these groups did any exercise for 20 days. The third and fourth groups consisted of the exercise group subjects; they were required to perform a 20-m shuttle run test every day for 20 days. The third group’s subjects, the placebo (E), only consumed water. The last group (GE) consumed glycerol followed by water. The Astrand Cycle Ergometer Test (ACET) was performed, and the Cosmed K4b2 portable gas analysis system was used to determine the aerobic capacity, while the Wingate Anaerobic Power Test (WAPT) was performed to determine the level of anaerobic power. The 20 Meter Shuttle Run Test (20MSRT) was performed after glycerol supplementation throughout the 20 days, and the exercise periods and distances were recorded. The glycerol supplement was found to have an increasing effect on aerobic and anaerobic performance in GS, E and GE. A similar effect was found for the covered distances and time in the same groups. However, an adverse effect was found on body weight. PMID:23487412

  4. Effect of Short-Term, High-Intensity Exercise on Anaerobic Threshold in Women.

    ERIC Educational Resources Information Center

    Evans, Blanche W.

    This study investigated the effects of a six-week, high-intensity cycling program on anaerobic threshold (AT) in ten women. Subjects trained four days a week using high-intensity interval-type cycle exercises. Workouts included six 4-minute intervals cycling at 85 percent maximal oxygen uptake (VO sub 2 max), separated by 3-minute intervals of…

  5. Pilot plant study of the effects of quebracho and wattle on anaerobic digestion

    SciTech Connect

    Eye, J.D.; Ficker, C.F.

    1982-01-01

    Quebracho and wattle tannin adversely affected the operational control required for the systems as well as CH4 production. The anaerobic organisms however degraded the tannins and the characteristic red color was effectively removed from the supernatant (liquid phase of digested sludge) during digestion.

  6. Start-up of a combined anaerobic/partial nitritation/anammox process for high-salt mustard wastewater treatment.

    PubMed

    Chen, You-Peng; Ma, Teng-Fei; Hu, Xiao; Fang, Fang; Shen, Yu; Yang, Ji-Xiang; Guo, Jin-Song; Bao, Zhen-Guo; Yan, Peng

    2015-01-01

    To treat high salinity wastewater from the mustard pickling industry, a combined anaerobic, partial nitritation (PN), and anammox process was employed using three connected reactors: an anaerobic sequencing batch biofilm reactor (ASBBR) for anaerobic treatment, a sequencing batch reactor (SBR) for PN, and an upflow anaerobic sludge blanket (UASB) for anammox. The start-up of the three individual reactors was investigated. Results showed that each reactor started up successfully, notwithstanding the stepwise increase of influent salinity to about 16.1 g NaCl/L. In the ASBBR, 89.7 % of chemical oxygen demand in the influent was removed and organic nitrogen was converted to ammonium (NH4 (+)-N). The SBR performed well with NO3 (-)-N concentration of 4.9 mg/L and ratio of NO2 (-)-N to NH4 (+)-N at the range of 1.0 to 1.3 in the effluent, which favored the anammox process. After the start-up of the UASB, the anammox process also showed stability and efficiency with a high total nitrogen removal efficiency of 86.2 % under high salinity of 12.0 g NaCl/L and nitrogen loading rate of 258 mg/(L · day).

  7. Start-up of a combined anaerobic/partial nitritation/anammox process for high-salt mustard wastewater treatment.

    PubMed

    Chen, You-Peng; Ma, Teng-Fei; Hu, Xiao; Fang, Fang; Shen, Yu; Yang, Ji-Xiang; Guo, Jin-Song; Bao, Zhen-Guo; Yan, Peng

    2015-01-01

    To treat high salinity wastewater from the mustard pickling industry, a combined anaerobic, partial nitritation (PN), and anammox process was employed using three connected reactors: an anaerobic sequencing batch biofilm reactor (ASBBR) for anaerobic treatment, a sequencing batch reactor (SBR) for PN, and an upflow anaerobic sludge blanket (UASB) for anammox. The start-up of the three individual reactors was investigated. Results showed that each reactor started up successfully, notwithstanding the stepwise increase of influent salinity to about 16.1 g NaCl/L. In the ASBBR, 89.7 % of chemical oxygen demand in the influent was removed and organic nitrogen was converted to ammonium (NH4 (+)-N). The SBR performed well with NO3 (-)-N concentration of 4.9 mg/L and ratio of NO2 (-)-N to NH4 (+)-N at the range of 1.0 to 1.3 in the effluent, which favored the anammox process. After the start-up of the UASB, the anammox process also showed stability and efficiency with a high total nitrogen removal efficiency of 86.2 % under high salinity of 12.0 g NaCl/L and nitrogen loading rate of 258 mg/(L · day). PMID:25240848

  8. A modified anaerobic digestion process with chemical sludge pre-treatment and its modelling.

    PubMed

    Hai, N M; Sakamoto, S; Le, V C; Kim, H S; Goel, R; Terashima, M; Yasui, H

    2014-01-01

    Activated Sludge Models (ASMs) assume an unbiodegradable organic particulate fraction in the activated sludge, which is derived from the decay of active microorganisms in the sludge and/or introduced from wastewater. In this study, a seasonal change of such activated sludge constituents in a municipal wastewater treatment plant was monitored for 1.5 years. The chemical oxygen demand ratio of the unbiodegradable particulates to the sludge showed a sinusoidal pattern ranging from 40 to 65% along with the change of water temperature in the plant that affected the decay rate. The biogas production in a laboratory-scale anaerobic digestion (AD) process was also affected by the unbiodegradable fraction in the activated sludge fed. Based on the results a chemical pre-treatment using H2O2 was conducted on the digestate to convert the unbiodegradable fraction to a biodegradable one. Once the pre-treated digestate was returned to the digester, the methane conversion increased up to 80% which was about 2.4 times as much as that of the conventional AD process, whilst 96% of volatile solids in the activated sludge was digested. From the experiment, the additional route of the organic conversion processes for the inert fraction at the pre-treatment stage was modelled on the ASM platform with reasonable simulation accuracy.

  9. Effects of psychological priming, video, and music on anaerobic exercise performance.

    PubMed

    Loizou, G; Karageorghis, C I

    2015-12-01

    Peak performance videos accompanied by music can help athletes to optimize their pre-competition mindset and are often used. Priming techniques can be incorporated into such videos to influence athletes' motivational state. There has been limited empirical work investigating the combined effects of such stimuli on anaerobic performance. The present study examined the psychological and psychophysiological effects of video, music, and priming when used as a pre-performance intervention for an anaerobic endurance task. Psychological measures included the main axes of the circumplex model of affect and liking scores taken pre-task, and the Exercise-induced Feeling Inventory, which was administered post-task. Physiological measures comprised heart rate variability and heart rate recorded pre-task. Fifteen males (age = 26.3 ± 2.8 years) were exposed to four conditions prior to performing the Wingate Anaerobic Test: music-only, video and music, video with music and motivational primes, and a no-video/no-music control. Results indicate that the combined video, music, and primes condition was the most effective in terms of influencing participants' pre-task affect and subsequent anaerobic performance; this was followed by the music-only condition. The findings indicate the utility of such stimuli as a pre-performance technique to enhance athletes' or exercisers' psychological states. PMID:25556962

  10. Effects of psychological priming, video, and music on anaerobic exercise performance.

    PubMed

    Loizou, G; Karageorghis, C I

    2015-12-01

    Peak performance videos accompanied by music can help athletes to optimize their pre-competition mindset and are often used. Priming techniques can be incorporated into such videos to influence athletes' motivational state. There has been limited empirical work investigating the combined effects of such stimuli on anaerobic performance. The present study examined the psychological and psychophysiological effects of video, music, and priming when used as a pre-performance intervention for an anaerobic endurance task. Psychological measures included the main axes of the circumplex model of affect and liking scores taken pre-task, and the Exercise-induced Feeling Inventory, which was administered post-task. Physiological measures comprised heart rate variability and heart rate recorded pre-task. Fifteen males (age = 26.3 ± 2.8 years) were exposed to four conditions prior to performing the Wingate Anaerobic Test: music-only, video and music, video with music and motivational primes, and a no-video/no-music control. Results indicate that the combined video, music, and primes condition was the most effective in terms of influencing participants' pre-task affect and subsequent anaerobic performance; this was followed by the music-only condition. The findings indicate the utility of such stimuli as a pre-performance technique to enhance athletes' or exercisers' psychological states.

  11. Biotic and abiotic processes contribute to successful anaerobic degradation of cyanide by UASB reactor biomass treating brewery waste water.

    PubMed

    Novak, Domen; Franke-Whittle, Ingrid H; Pirc, Elizabeta Tratar; Jerman, Vesna; Insam, Heribert; Logar, Romana Marinšek; Stres, Blaž

    2013-07-01

    In contrast to the general aerobic detoxification of industrial effluents containing cyanide, anaerobic cyanide degradation is not well understood, including the microbial communities involved. To address this knowledge gap, this study measured anaerobic cyanide degradation and the rearrangements in bacterial and archaeal microbial communities in an upflow anaerobic sludge blanket (UASB) reactor biomass treating brewery waste water using bio-methane potential assays, molecular profiling, sequencing and microarray approaches. Successful biogas formation and cyanide removal without inhibition were observed at cyanide concentrations up to 5 mg l(-1). At 8.5 mg l(-1) cyanide, there was a 22 day lag phase in microbial activity, but subsequent methane production rates were equivalent to when 5 mg l(-1) was used. The higher cumulative methane production in cyanide-amended samples indicated that part of the biogas was derived from cyanide degradation. Anaerobic degradation of cyanide using autoclaved UASB biomass proceeded at a rate more than two times lower than when UASB biomass was not autoclaved, indicating that anaerobic cyanide degradation was in fact a combination of simultaneous abiotic and biotic processes. Phylogenetic analyses of bacterial and archaeal 16S rRNA genes for the first time identified and linked the bacterial phylum Firmicutes and the archaeal genus Methanosarcina sp. as important microbial groups involved in cyanide degradation. Methanogenic activity of unadapted granulated biomass was detected at higher cyanide concentrations than reported previously for the unadapted suspended biomass, making the aggregated structure and predominantly hydrogenotrophic nature of methanogenic community important features in cyanide degradation. The combination of brewery waste water and cyanide substrate was thus shown to be of high interest for industrial level anaerobic cyanide degradation.

  12. Effect of cobalt on the anaerobic thermophilic conversion of methanol.

    PubMed

    Paulo, Paula L; Jiang, Bo; Cysneiros, Denise; Stams, Alfons J M; Lettinga, Gatze

    2004-02-20

    The importance of cobalt on the anaerobic conversion of methanol under thermophilic conditions was studied in three parallel lab-scale UASB-reactors and in cobalt-limited enriched cultures. Reactors R1, R2, and R3 were fed with methanol in a bicarbonate-buffered medium, supplied with iron and macronutrients: in R1 all metals were supplied (control), R2 was cobalt deprived, and in R3 all metals were deprived. In the 136 days of continuous experiment, a drop in performance was observed over the last 30 days. Particularly in R3, both methanol removal and methane formation dropped by 7.1% and 13.7%, respectively, compared to the control reactor, R1. When the medium was cobalt-deprived, acetate was not produced and, as a consequence, the enriched consortium lost its capacity to degrade acetate, indicating that the acetotrophic microorganisms were washed out. The addition of 0.5 microM of cobalt to a cobalt-deprived enrichment culture led to acetate accumulation. The results obtained in this study indicate that the mixed consortium requires a proper amount of cobalt, and its addition to a concentration of 0.1 microM leads to the highest methanol conversion rate, with methane as the sole end product from methanol.

  13. Effect of Forward and Backward Locomotion Training on Anaerobic Performance and Anthropometrical Composition

    PubMed Central

    Kachanathu, Shaji John; Alenazi, Aqeel M; Algarni, Abdulrahman D; Hafez, Ashraf Ramadan; Hameed, Unaise A; Nuhmani, Shibili; Alghamdi, Mansour S; Melam, Ganeshwerarao

    2014-01-01

    [Purpose] Forward walking (FW) and backward walking (BW) on a treadmill is a common tool for lower extremity rehabilitation in the clinical setting. The purpose of this study was to evaluate the effects on anaerobic performance and anthropometrical adaptations during FW and BW on a treadmill. [Subjects and Methods] A convenience sample of thirty healthy male subjects with a mean age of 20.93 ± 2.54 years participated in this study. Subjects were divided into 2 groups, a Forward Walking Group (FWG) (n=15) and a Backward Walking Group (BWG) (n=15), which performed FW and BW on a treadmill at 10° inclination, respectively. The training consisted of three sessions per week for 6 weeks. Study outcomes such as anaerobic performance and anthropometrical body composition were measured at pre- and post-intervention. [Results] Both FW and BW improved anaerobic performance significantly, and the BW group showed better performance than FW. However, changes in anthropometrical body composition were found to be not significant after six weeks of intervention in both the FW and BW groups. [Conclusions] BW training in rehabilitation can be considered more effective than FW at improving anaerobic performance. We also conclude that six weeks of FW and BW training is insufficient for eliciting changes in the body composition. PMID:25540487

  14. Effect of thermal hydrolysis and ultrasounds pretreatments on foaming in anaerobic digesters.

    PubMed

    Alfaro, N; Cano, R; Fdz-Polanco, F

    2014-10-01

    Foam appears regularly in anaerobic digesters producing operational and safety problems. In this research, based on the operational observation at semi-industrial pilot scale where sludge pretreatment mitigated foaming in anaerobic digesters, this study aimed at evaluating any potential relationship between foaming tools applied to activated sludge at lab-scale (foam potential, foam stability and Microthrix parvicella abundance) and the experimental behavior observed in pilot scale and full-scale anaerobic digesters. The potential of thermal hydrolysis and ultrasounds for reducing foaming capacity was also evaluated. Filamentous bacteria abundance was directly linked to foaming capacity in anaerobic processes. A maximum reduction of M.parvicella abundance (from 5 to 2) was reached using thermal hydrolysis with steam explosion at 170°C and ultrasounds at 66.7kWh/m(3), showing both good anti-foaming properties. On the other hand, foam potential and stability determinations showed a lack of consistency with the bacteria abundance results and experimental evidences.

  15. Process performance of high-solids batch anaerobic digestion of sewage sludge.

    PubMed

    Liao, Xiaocong; Li, Huan; Cheng, Yingchao; Chen, Nan; Li, Chenchen; Yang, Yuning

    2014-01-01

    The characteristics of high-solids anaerobic digestion (AD) of sewage sludge were investigated by comparison with conventional low-solids processes. A series of batch experiments were conducted under mesophilic condition and the initial solid contents were controlled at four levels of 1.79%, 4.47%, 10.28% and 15.67%. During these experiments, biogas production, organic degradation and intermediate products were monitored. The results verified that high-solids batch AD of sewage sludge was feasible. Compared with the low-solids AD with solid contents of 1.79% or 4.47%, the high-solids processes decreased the specific biogas yield per gram of sludge volatile solids slightly, achieved the same organic degradation rate of about 40% within extended degradation time, but increased the volumetric biogas production rate and the treatment capability of digesters significantly. The blocked mass and energy transfer, the low substrate to inoculum rate and the excessive cumulative free ammonia were the main factors impacting the performance of high-solids batch AD.

  16. Two-phase thermophilic anaerobic digestion process for biohythane production treating biowaste: preliminary results.

    PubMed

    Cavinato, C; Bolzonella, D; Fatone, F; Giuliano, A; Pavan, P

    2011-01-01

    This paper deals with the optimization of a two-phase anaerobic process treating biowaste for hydrogen and methane production. Neither physical nor chemical pre-treatments were used to optimize the process. The work was carried out at pilot scale, using two CSTRs (200 and 380 L working volume respectively) both maintained at thermophilic temperature (55 C) and fed semi-continuously with biowaste. The experiment was divided into three periods; during the first two periods the organic loading rate was maintained at 20 kg TVS/m3 d and the hydraulic retention time was changed from 6.6 to 3.3 days, while in the last period the digestate of the second reactor was recirculated to the first reactor in order to buffer the system and control pH at levels around 5. The HRT was maintained at 3.3 days and the OLR was decreased at 16.5 kg TVS/m3 d. The best yield was obtained in the last period where a specific hydrogen production of 50.9 L/kg VSfed was reached, with a H2 content in biogas from the first reactor of 36%. The methanogenic stage after the hydrogen conversion reached a specific biogas production of 0.62 m3/kg VSfed and an overall organic removal above 70%, without any stability problem. The overall biogas production was some 1.5 m3 per day with a gas composition of 10% H2 and 50% CH4.

  17. Techno-economic evaluation of stillage treatment with anaerobic digestion in a softwood-to-ethanol process

    PubMed Central

    2010-01-01

    Background Replacing the energy-intensive evaporation of stillage by anaerobic digestion is one way of decreasing the energy demand of the lignocellulosic biomass to the ethanol process. The biogas can be upgraded and sold as transportation fuel, injected directly into the gas grid or be incinerated on-site for combined heat and power generation. A techno-economic evaluation of the spruce-to-ethanol process, based on SO2-catalysed steam pretreatment followed by simultaneous saccharification and fermentation, has been performed using the commercial flow-sheeting program Aspen Plus™. Various process configurations of anaerobic digestion of the stillage, with different combinations of co-products, have been evaluated in terms of energy efficiency and ethanol production cost versus the reference case of evaporation. Results Anaerobic digestion of the stillage showed a significantly higher overall energy efficiency (87-92%), based on the lower heating values, than the reference case (81%). Although the amount of ethanol produced was the same in all scenarios, the production cost varied between 4.00 and 5.27 Swedish kronor per litre (0.38-0.50 euro/L), including the reference case. Conclusions Higher energy efficiency options did not necessarily result in lower ethanol production costs. Anaerobic digestion of the stillage with biogas upgrading was demonstrated to be a favourable option for both energy efficiency and ethanol production cost. The difference in the production cost of ethanol between using the whole stillage or only the liquid fraction in anaerobic digestion was negligible for the combination of co-products including upgraded biogas, electricity and district heat. PMID:20843330

  18. [Accelerating effects of immobilized anthanquinone on the anaerobic biodegradation].

    PubMed

    Guo, Jian-bo; Zhou, Ji-ti; Wang, Dong; Tian, Cun-ping; Wang, Ping; Wang, Jing; Salah, Uddin; Li, Li-hua

    2006-10-01

    The accelerating effect of anthanquinone as a redox mediator in the bio-decolorization was conducted. Decolorization of azo dyes was carried out experimentally using the salt-tolerant bacteria under immobilized anthanquinone and high salt conditions. Anthnaquinone used as a redox mediator was able to increase the decolorization rate of wastewater containing azo dyes, and was immobilized by entrapment in calcium alginate (CA), polyvinyl alcohol (PVA)-H3BO3, polyvinyl alcohol (PVA)-calcium alginate (CA) and agar, respectively. The effects of various operating conditions such as anthnaquinone bead number and dissolved oxygen on microbial decolorization were investigated experimentally. At the same time, immobilized anthanquinone was tested to assess the effects on the change of the oxidation-reduction potential (ORP) values during the decolorization processes. High decolorization rate was obtained in the presence of 200 anthnaquinone immobilization beads at 30 degrees C, which increased 1.5-2 fold, in comparison with the control of free-anthanquinone. The oxidation-reduction potential (ORP) values stabilized around -260 to approximately -265 mV after 6 hours anoxic conditions, which lowered ORP values around -10 to approximately -15 mV by anthanquinone. The reusability of the anthnaquinone immobilization beads was evaluated with repeated-bacth decolorization experiments. After four repeated experiments, the decolorization rate of calcium alginate (CA) immobilized anthnaquinone retained over 90% of their original activity.

  19. Effect of key parameters on nitric oxide removal by an anaerobic rotating drum biofilter.

    PubMed

    Jun, C; Yifeng, J; Haolei, S; Jianmeng, C

    2008-11-01

    A bench-scale anaerobic rotating drum biofilter (RDB) was used to demonstrate its ability to treat off-gas containing nitric oxide (NO), by examining the inlet NO concentration and operating temperature as the selected operational parameters. After 30 days' start-up, the long-term stable performance of the RDB was investigated for 100 days. The inlet NO concentration fluctuated between approximately 90 and 433 mg m3, while the removal efficiency was maintained at 60-85%, and the average elimination capacity was 10.4 g m(-3) h(-1). With the inlet NO load increasing from 150 to 1300 mg m(-3), the elimination capacity of the RDB increased from 3 to 26 g m(-3) h(-1) while the removal efficiency decreased sharply from 86% to 40%. At a lower range of NO concentrations (< 150 mg m(-3)), the temperature had no visible effect on the removal efficiency, whereas if NO concentrations were higher than 150 mg m(-3), a non-negligible enhancement of NO removal was found when the temperature was gradually raised from 25 degrees C to 30 degrees C. The optimal temperature was around 30 degrees C. The results proved that the RDB had more advantages over a traditional bioreactor in terms of low mass transfer resistance, high effective utility of packing materials, high even distribution of biomass and no biomass clogging of packing materials. The RDB proved to be an effective treatment process for NO removal. PMID:18975856

  20. Effects of alkalinity sources on the stability of anaerobic digestion from food waste.

    PubMed

    Chen, Shujun; Zhang, Jishi; Wang, Xikui

    2015-11-01

    This study investigated the effects of some alkalinity sources on the stability of anaerobic digestion (AD) from food waste (FW). Four alkalinity sources, namely lime mud from papermaking (LMP), waste eggshell (WES), CaCO3 and NaHCO3, were applied as buffer materials and their stability effects were evaluated in batch AD. The results showed that LMP and CaCO3 had more remarkable effects than NaHCO3 and WES on FW stabilization. The methane yields were 120.2, 197.0, 156.2, 251.0 and 194.8 ml g(-1) VS for the control and synergistic digestions of CaCO3, NaHCO3, LMP and WES added into FW, respectively. The corresponding final alkalinity reached 5906, 7307, 9504, 7820 and 6782 mg l(-1), while the final acidities were determined to be 501, 200, 50, 350 and 250 mg l(-1), respectively. This indicated that the synergism between alkalinity and inorganic micronutrients from different alkalinity sources played an important role in the process stability of AD from FW.

  1. Effects of alkalinity sources on the stability of anaerobic digestion from food waste.

    PubMed

    Chen, Shujun; Zhang, Jishi; Wang, Xikui

    2015-11-01

    This study investigated the effects of some alkalinity sources on the stability of anaerobic digestion (AD) from food waste (FW). Four alkalinity sources, namely lime mud from papermaking (LMP), waste eggshell (WES), CaCO3 and NaHCO3, were applied as buffer materials and their stability effects were evaluated in batch AD. The results showed that LMP and CaCO3 had more remarkable effects than NaHCO3 and WES on FW stabilization. The methane yields were 120.2, 197.0, 156.2, 251.0 and 194.8 ml g(-1) VS for the control and synergistic digestions of CaCO3, NaHCO3, LMP and WES added into FW, respectively. The corresponding final alkalinity reached 5906, 7307, 9504, 7820 and 6782 mg l(-1), while the final acidities were determined to be 501, 200, 50, 350 and 250 mg l(-1), respectively. This indicated that the synergism between alkalinity and inorganic micronutrients from different alkalinity sources played an important role in the process stability of AD from FW. PMID:26391806

  2. Energy efficacy used to score organic refuse pretreatment processes for hydrogen anaerobic production.

    PubMed

    Ruggeri, Bernardo; Luongo Malave, Andrea C; Bernardi, Milena; Fino, Debora

    2013-11-01

    The production of hydrogen through Anaerobic Digestion (AD) has been investigated to verify the efficacy of several pretreatment processes. Three types of waste with different carbon structures have been tested to obtain an extensive representation of the behavior of the materials present in Organic Waste (OW). The following types of waste were selected: Sweet Product Residue (SPR), i.e., confectionary residue removed from the market after the expiration date, Organic Waste Market (OWM) refuse from a local fruit and vegetable market, and Coffee Seed Skin (CSS) waste from a coffee production plant. Several pretreatment processes have been applied, including physical, chemical, thermal, and ultrasonic processes and a combination of these processes. Two methods have been used for the SPR to remove the packaging, manual (SPR) and mechanical (SPRex). A pilot plant that is able to extrude the refuse to 200atm was utilized. Two parameters have been used to score the different pretreatment processes: efficiency (ξ), which takes into account the amount of energy produced in the form of hydrogen compared with the available energy embedded in the refuse, and efficacy (η), which compares the efficiency obtained using the pretreated refuse with that obtained using the untreated refuse. The best result obtained for the SPR was the basic pretreatment, with η=6.4, whereas the thermal basic pretreatment gave the highest value, η=17.0 for SPRex. The best result for the OWM was obtained through a combination of basic/thermal pretreatments with η=9.9; lastly, the CSS residue with ultrasonic pretreatment produced the highest quantity of hydrogen, η=5.2.

  3. Energy efficacy used to score organic refuse pretreatment processes for hydrogen anaerobic production.

    PubMed

    Ruggeri, Bernardo; Luongo Malave, Andrea C; Bernardi, Milena; Fino, Debora

    2013-11-01

    The production of hydrogen through Anaerobic Digestion (AD) has been investigated to verify the efficacy of several pretreatment processes. Three types of waste with different carbon structures have been tested to obtain an extensive representation of the behavior of the materials present in Organic Waste (OW). The following types of waste were selected: Sweet Product Residue (SPR), i.e., confectionary residue removed from the market after the expiration date, Organic Waste Market (OWM) refuse from a local fruit and vegetable market, and Coffee Seed Skin (CSS) waste from a coffee production plant. Several pretreatment processes have been applied, including physical, chemical, thermal, and ultrasonic processes and a combination of these processes. Two methods have been used for the SPR to remove the packaging, manual (SPR) and mechanical (SPRex). A pilot plant that is able to extrude the refuse to 200atm was utilized. Two parameters have been used to score the different pretreatment processes: efficiency (ξ), which takes into account the amount of energy produced in the form of hydrogen compared with the available energy embedded in the refuse, and efficacy (η), which compares the efficiency obtained using the pretreated refuse with that obtained using the untreated refuse. The best result obtained for the SPR was the basic pretreatment, with η=6.4, whereas the thermal basic pretreatment gave the highest value, η=17.0 for SPRex. The best result for the OWM was obtained through a combination of basic/thermal pretreatments with η=9.9; lastly, the CSS residue with ultrasonic pretreatment produced the highest quantity of hydrogen, η=5.2. PMID:23891078

  4. Volatile fatty acids production from anaerobic treatment of cassava waste water: effect of temperature and alkalinity.

    PubMed

    Hasan, Salah Din Mahmud; Giongo, Citieli; Fiorese, Mônica Lady; Gomes, Simone Damasceno; Ferrari, Tatiane Caroline; Savoldi, Tarcio Enrico

    2015-01-01

    The production of volatile fatty acids (VFAs), intermediates in the anaerobic degradation process of organic matter from waste water, was evaluated in this work. A batch reactor was used to investigate the effect of temperature, and alkalinity in the production of VFAs, from the fermentation of industrial cassava waste water. Peak production of total volatile fatty acids (TVFAs) was observed in the first two days of acidogenesis. A central composite design was performed, and the highest yield (3400 mg L(-1) of TVFA) was obtained with 30°C and 3 g L(-1) of sodium bicarbonate. The peak of VFA was in 45 h (pH 5.9) with a predominance of acetic (63%) and butyric acid (22%), followed by propionic acid (12%). Decreases in amounts of cyanide (12.9%) and chemical oxygen demand (21.6%) were observed, in addition to the production of biogas (0.53 cm(3) h(-1)). The process was validated experimentally and 3400 g L(-1) of TVFA were obtained with a low relative standard deviation.

  5. Effects of chemical amendments on the lability and speciation of metals in anaerobically digested biosolids.

    PubMed

    Donner, Erica; Brunetti, Gianluca; Zarcinas, Bernie; Harris, Paul; Tavakkoli, Ehsan; Naidu, Ravi; Lombi, Enzo

    2013-10-01

    The interaction of inorganic contaminants present in biosolids with iron, aluminum, and manganese oxy/hydroxides has been advocated as a key mechanism limiting their bioavailability. In this study, we investigated whether this is indeed the case, and further, whether it can be exploited to produce optimized biosolids products through the addition of chemical additives during sewage sludge processing. Experiments were conducted to investigate whether the addition of iron- and aluminum-based amendments (at 5 different rates) during the anaerobic digestion phase of wastewater treatment can effectively change the speciation or lability of contaminant metals (copper, zinc and cadmium) in biosolids destined for use in agriculture. The performance of the bioreactors was monitored throughout and the speciation and lability were determined in both fresh and 3-month aged biosolids using X-ray absorption spectroscopy (Cu, Zn) and isotopic dilution ((65)Cu, (65)Zn, (109)Cd). The tested amendments (FeCl3, Al2(SO4)3, and Al-rich water treatment residual) did not cause significant changes in metal speciation and were of limited use for reducing the lability of contaminant metals in good quality biosolids (suitable for use in agriculture), suggesting that high affinity binding sites were already in excess in these materials. However, the use of chemical amendments may offer advantages in terms of treatment process optimization and may also be beneficial when biosolids are used for contaminated site remediation. PMID:23981056

  6. Effect of saponification on the anaerobic digestion of solid fatty residues.

    PubMed

    Mouneimne, A H; Carrère, H; Bernet, N; Delgenès, J P

    2003-10-01

    In France, fatty residues considered as "non-ultimate" waste will not be accepted in landfill from 2002, in accordance with French legislation. Anaerobic digestion appears as an alternative process to mobilize and profitably use such fermentable waste. In this work, the effect of an alkaline pretreatment on the degradation of hexane extractible matter (HEM) and the production of volatile fatty acids (VFAs) was compared in reactors working at pH 6.5 and 8.5. The results obtained showed that 40% (+/- 0.1) of HEM were degraded at pH 8.5 versus 10% (+/- 0.3) at pH 6.5, regardless of the alkali agent used to saponify the greasy wastes. The highest performances of VFA production (8.45% +/- 0.3) were obtained at pH 8.5 with greases saponified by potassium hydroxide, compared to results (4.25% +/- 0.1) with greasy waste saponified by sodium hydroxide. This difference in VFA production might be attributable to biotoxic molecules generated during the saponification of greases by soda, limiting consequently the VFA production process.

  7. The effect of managing nutrients in the performance of anaerobic digesters of municipal wastewater treatment plants.

    PubMed

    Demirer, Sibel Uludag; Taskin, Bilgin; Demirer, Goksel N; Duran, Metin

    2013-09-01

    Is it possible to create conditions in the anaerobic digesters to control nutrients without changing the performance of a reactor? This study investigates an answer for this question. To this purpose, anaerobic reactors are operated at high concentrations of Mg(2+) ion to harvest the nutrient ions (NH4 (+) and PO4 (3-)) in the form of struvite, that is, magnesium ammonium phosphate. The effects of this modification on the anaerobic digestion of sewage sludge were investigated in terms of chemical oxygen demand (COD) removal and cumulative CH4 production as well as the changes in the biological diversity. The results showed that approximately 50 % of the nutrients (NH4 (+) and PO4 (3-)) were removed regardless of the method adopted for the addition of Mg(2+) ion, slug or daily dosing. The numbers of Methanosaeta and Methanosarcina in the samples withdrawn prior to and after the addition of Mg(2+) did not show significant difference according to the results obtained from qPCR analyses. The research results showed that the addition of Mg(2+) into the anaerobic digesters in municipal wastewater treatment facilities may help to remove the nutrients from the effluent while recovering in their solid forms. PMID:23090053

  8. The effect of water restriction on anaerobic power and vertical jumping height in basketball players.

    PubMed

    Hoffman, J R; Stavsky, H; Falk, B

    1995-05-01

    This study examined the effect of high intensity, moderate duration (40 min) exercise and water restriction on anaerobic power, vertical jumping height, and basketball shooting performance. Ten healthy male basketball players participated in two simulated '2 on 2 full-court' basketball games. Water consumption was permitted in one game (Wa) but not in the other (NWa), in a balanced cross-over design. Subjects began each game euhydrated. All jump tests (squat jump, counter movement jump, and 30 second jump test) were performed prior to, at half-time, and immediately following each game (POST). Performance was measured by both field goal (FG%) and free throw (FT%) percentages recorded during each half. Players incurred a -1.9 +/- 0.4% body weight loss during NWa. No significant differences were observed between WA and NWa in anaerobic power, squat jump, or counter movement jump. However, a 19% difference in anaerobic power (p > 0.05) was observed between Wa (36.1 +/- 4.8 W.kg-1) and NWa (30.4 +/- 6.6 W.kg-1) at POST. No significant differences were observed between Wa and NWa in both FG% and FT% however, an 8.1% decrease (p > 0.05) in FG% was seen between the first and second half during NWa. Although the decreases in anaerobic power and FG% did not reach significance, the results suggest that the combination of high intensity, moderate duration exercise, and fluid restriction might be detrimental to performance. PMID:7657413

  9. The effect of water restriction on anaerobic power and vertical jumping height in basketball players.

    PubMed

    Hoffman, J R; Stavsky, H; Falk, B

    1995-05-01

    This study examined the effect of high intensity, moderate duration (40 min) exercise and water restriction on anaerobic power, vertical jumping height, and basketball shooting performance. Ten healthy male basketball players participated in two simulated '2 on 2 full-court' basketball games. Water consumption was permitted in one game (Wa) but not in the other (NWa), in a balanced cross-over design. Subjects began each game euhydrated. All jump tests (squat jump, counter movement jump, and 30 second jump test) were performed prior to, at half-time, and immediately following each game (POST). Performance was measured by both field goal (FG%) and free throw (FT%) percentages recorded during each half. Players incurred a -1.9 +/- 0.4% body weight loss during NWa. No significant differences were observed between WA and NWa in anaerobic power, squat jump, or counter movement jump. However, a 19% difference in anaerobic power (p > 0.05) was observed between Wa (36.1 +/- 4.8 W.kg-1) and NWa (30.4 +/- 6.6 W.kg-1) at POST. No significant differences were observed between Wa and NWa in both FG% and FT% however, an 8.1% decrease (p > 0.05) in FG% was seen between the first and second half during NWa. Although the decreases in anaerobic power and FG% did not reach significance, the results suggest that the combination of high intensity, moderate duration exercise, and fluid restriction might be detrimental to performance.

  10. Acute effects of jaw clenching using a customized mouthguard on anaerobic ability and ventilatory flows.

    PubMed

    Morales, Jose; Buscà, Bernat; Solana-Tramunt, Mònica; Miró, Adrià

    2015-12-01

    The latest findings on the ergogenic effects of a dentistry-design, bite-aligning mouthpiece require additional research to assess its impact on anaerobic ability and ventilatory parameters. This paper was aimed at determining the ergogenic acute effects of wearing a custom-made mouthpiece on oral airflow dynamics, 30-s Wingate Anaerobic Test performance parameters. Twenty-eight healthy and physically-active male subjects (age: 24.50 ± 3.32, height: 181.34 ± 7.4, weight: 78.14 ± 8.21), were voluntarily studied. The subjects were first briefed on the test protocols, and then performed the 30s Wingate test and Spirometer test. The experimental trials were performed in a random counterbalanced order. We evaluate maximum expiratory volume (VEmax L min(-1)), mean power (W kg(-1)), peak power (W kg(-1)), time to peak (s), rate to fatigue (Ws(-1)) and lactate production (mMol L(-1)), rate of perceived exertion (RPE). There were significant differences between mouthguard and no-mouthguard conditions in mean power (W kg(-1)), peak power (W kg(-1)), time to peak (s), and rate to fatigue (Ws(-1)) for the 30-s Wingate Anaerobic Test. Significantly lower lactate production (mMol L(-1)) was observed, in mouthguard condition but no significant differences were found in RPE. In airflow dynamics, the VEmax L min(-1) was significantly higher when comparing the mouthguard and the no mouthguard conditions in both forced and unforced conditions. In conclusion, wearing a customized mouthguard improves anaerobic ability and increases forced expiratory volume. This study will help practitioners improve athlete's performance in anaerobic activities where high intensity action might provoke jaw-clenching, contributing in reductions of lactate and fatigue, and improving ventilatory parameters.

  11. Transferring of components and energy output in industrial sewage sludge disposal by thermal pretreatment and two-phase anaerobic process.

    PubMed

    Yang, Xiaoyi; Wang, Xin; Wang, Lei

    2010-04-01

    For a better sewage sludge disposal and more efficient energy reclamation, transforming of components and energy in sludge by thermal and WAO pretreatment followed by two-phase anaerobic UASB process were studied in the pilot scale. Biogas outputs and the qualities and quantities of the effluent and solid residue were compared with a traditional anaerobic sludge digestion. Sludge components, including carbon, nitrogen, phosphorus, sulphur, were observed and mass balances were discussed throughout the process. The input and output energy balance was also studied. Results showed different trait to compare with biogas outputs in terms of COD added and raw sludge added. Pretreatment improved the transformation of carbon substances into biogas production with higher carbon removal and higher VSS removal. Comparing the energy obtained from biogas production with energy inputs required for pretreatment, energy output in the whole process decreased with higher pretreatment temperature.

  12. Process stability and microbial community structure in anaerobic hydrogen-producing microflora from food waste containing kimchi.

    PubMed

    Jo, Ji Hye; Jeon, Che Ok; Lee, Dae Sung; Park, Jong Moon

    2007-09-15

    Hydrogen production by the dark fermentation of food wastes is an economic and environmentally friendly technology to produce the clean energy source as well as to treat the problematic wastes. However, the long-term operations of the continuous anaerobic reactor for fermentative hydrogen production were frequently unstable. In this study, the structure of microbial community within the anaerobic reactor during unstable hydrogen production was examined by denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP) techniques. The changes in microbial community from H(2)-producing Clostridium spp. to lactic acid-producing Lactobacillus spp. were well coincident with the unexpected process failures and the changes of metabolites concentrations in the effluent of the anaerobic reactor. As the rate of hydrogen production decreased, effluent lactic acid concentration increased. Low rate of hydrogen production and changes in microbial community were related to the 'kimchi' content and storage temperature of food waste feed solution. After low temperature control of the storage tank of the feed solution, any significant change in microbial community within the anaerobic reactor did not occur and the hydrogen production was very stably maintained for a long time.

  13. Application of the upflow anaerobic sludge bed (UASB) process for treatment of complex wastewaters at low temperatures

    SciTech Connect

    Koster, I.W.; Lettinga, G.

    1985-10-01

    The feasibility of the upflow anaerobic sludge bed (UASB) process for the treatment of potato starch wastewater at low ambient temperatures was demonstrated by operating two 5.65 l reactors at 14 degrees C and 20 degrees C, respectively. The organic space loading rates achieved in these laboratory-scale reactors were 3 kg COD/cubic m/day at 14 degrees C and 4-5 kg COD/cubic m/day at 20 degrees C. The corresponding sludge loading rates were 0.12 kg COD/kg VSS/day at 14 degrees C and 0.16-0.18 kg COD/kg VSS/day at 20 degrees C. These findings are of considerable practical importance because application of anaerobic treatment at low ambient temperatures will lead to considerable savings in energy needed for operating the process. As compared with various other anaerobic wastewater treatment processes, a granular sludge upflow process represents one of the best options developed so far. Although the overall sludge yield under psychrophilic conditions is slightly higher than under optimal mesophilic conditions, this doesn't seriously hamper the operation of the process. The extra sludge yield, due to accumulation of slowly hydrolyzing substrate ingredients, was 4.75% of the COD input at 14 degrees C and 1.22% of the COD input at 20 degrees C. 26 references.

  14. Dry anaerobic digestion of cow dung for methane production: effect of mixing.

    PubMed

    Jha, Ajay Kumar; Li, Jianzheng; Ban, Qiaoying; Zhang, Liguo; Zhao, Bowei

    2012-12-01

    The performance characteristics of a dry batch reactor with a blender treating cow dung has been evaluated for 35 days in a single-stage batch reactor of 3 L effective volume at 35 +/- 1 degree C to investigate the effect of continuous-mixing on biogas production and organic materials removal. The results showed that the performance of unmixed and mixed digesters was quite different and the dry digester with mixing system produced methane of 0.358 LCH4/gVS(r) which was 7.50% higher than that for unmixed digester. Moreover, the organic material removal efficiency was increased by 9.73% in term of VS. The wide diversity of prominent bacteria and methanogenic archaea affiliated with all steps along the anaerobic degradation pathway made the process stable. But the dry digester with mixing system during start up was not beneficial, as it resulted in relatively higher volatile fatty acids, higher volatile fatty acid to alkalinity ratio, lower pH and consequently prolonged start up time. PMID:24261113

  15. Effect of temperature on anaerobic treatment of black water in UASB-septic tank systems.

    PubMed

    Luostarinen, Sari; Sanders, Wendy; Kujawa-Roeleveld, Katarzyna; Zeeman, Grietje

    2007-03-01

    The effect of northern European seasonal temperature changes and low temperature on the performance of upflow anaerobic sludge blanket (UASB)-septic tanks treating black water was studied. Three UASB-septic tanks were monitored with different operational parameters and at different temperatures. The results indicated the feasibility of the UASB-septic tank for (pre)treatment of black water at low temperatures with respect to removal of suspended solids and dissolved organic material. Inoculum sludge had little effect on COD(ss) removal, though in the start-up phase some poorly adapted inoculum disintegrated and washed out, thus requiring consideration when designing the process. Removal of COD(dis) was at first negative, but improved as the sludge adapted to low temperature. The UASB-septic tank alone did not comply with Finnish or Dutch treatment requirements and should therefore be considered mainly as a pre-treatment method. However, measuring the requirements as mgCOD l(-1) may not always be the best method, as the volume of the effluent discharged is also an important factor in the final amount of COD entering the receiving water bodies.

  16. Ubiquitous anaerobic ammonium oxidation in inland waters of China: an overlooked nitrous oxide mitigation process.

    PubMed

    Zhu, Guibing; Wang, Shanyun; Zhou, Leiliu; Wang, Yu; Zhao, Siyan; Xia, Chao; Wang, Weidong; Zhou, Rong; Wang, Chaoxu; Jetten, Mike S M; Hefting, Mariet M; Yin, Chengqing; Qu, Jiuhui

    2015-01-01

    Denitrification has long been regarded as the only pathway for terrestrial nitrogen (N) loss to the atmosphere. Here we demonstrate that large-scale anaerobic ammonium oxidation (anammox), an overlooked N loss process alternative to denitrification which bypasses nitrous oxide (N2O), is ubiquitous in inland waters of China and contributes significantly to N loss. Anammox rates in aquatic systems show different levels (1.0-975.9 μmol N m(-2) h(-1), n = 256) with hotspots occurring at oxic-anoxic interfaces and harboring distinct biogeochemical and biogeographical features. Extrapolation of these results to the China-national level shows that anammox could contribute about 2.0 Tg N yr(-1), which equals averagely 11.4% of the total N loss from China's inland waters. Our results indicate that a significant amount of the nitrogen lost from inland waters bypasses denitrification, which is important for constructing more accurate climate models and may significantly reduce potential N2O emission risk at a large scale. PMID:26610807

  17. Continuous cultivation of Chlorella pyrenoidosa using anaerobic digested starch processing wastewater in the outdoors.

    PubMed

    Chu, Hua-Qiang; Tan, Xiao-Bo; Zhang, Ya-Lei; Yang, Li-Bin; Zhao, Fang-Chao; Guo, Jun

    2015-06-01

    Microalgae cultivation using wastewater might be a suitable approach to support sustainable large-scale biomass production. Its compelling characteristics included the recycling of nutrients and water resources, reducing carbon emissions and harvesting available biomass. In outdoor batch and continuous cultures, Chlorella pyrenoidosa completely adapted to anaerobic digested starch processing wastewater and was the dominant microorganism in the photobioreactor. However, seasonal changes of environmental conditions significantly influenced biomass growth and lipid production. The long-term outdoor operation demonstrated that the biomass concentration and productivity in continuous operations at different hydraulic retention times (HRTs) can be successfully predicted using the kinetic growth parameters obtained from the batch culture. A moderate HRT (4days) in the summer provided the best microalgae and lipid production and achieved relatively high biomass concentrations of 1.29-1.62g/L, biomass productivities of 342.6±12.8mg/L/d and lipids productivities of 43.37±7.43mg/L/d.

  18. Ubiquitous anaerobic ammonium oxidation in inland waters of China: an overlooked nitrous oxide mitigation process

    PubMed Central

    Zhu, Guibing; Wang, Shanyun; Zhou, Leiliu; Wang, Yu; Zhao, Siyan; Xia, Chao; Wang, Weidong; Zhou, Rong; Wang, Chaoxu; Jetten, Mike S. M.; Hefting, Mariet M.; Yin, Chengqing; Qu, Jiuhui

    2015-01-01

    Denitrification has long been regarded as the only pathway for terrestrial nitrogen (N) loss to the atmosphere. Here we demonstrate that large-scale anaerobic ammonium oxidation (anammox), an overlooked N loss process alternative to denitrification which bypasses nitrous oxide (N2O), is ubiquitous in inland waters of China and contributes significantly to N loss. Anammox rates in aquatic systems show different levels (1.0–975.9 μmol N m−2 h−1, n = 256) with hotspots occurring at oxic-anoxic interfaces and harboring distinct biogeochemical and biogeographical features. Extrapolation of these results to the China-national level shows that anammox could contribute about 2.0 Tg N yr−1, which equals averagely 11.4% of the total N loss from China’s inland waters. Our results indicate that a significant amount of the nitrogen lost from inland waters bypasses denitrification, which is important for constructing more accurate climate models and may significantly reduce potential N2O emission risk at a large scale. PMID:26610807

  19. Continuous cultivation of Chlorella pyrenoidosa using anaerobic digested starch processing wastewater in the outdoors.

    PubMed

    Chu, Hua-Qiang; Tan, Xiao-Bo; Zhang, Ya-Lei; Yang, Li-Bin; Zhao, Fang-Chao; Guo, Jun

    2015-06-01

    Microalgae cultivation using wastewater might be a suitable approach to support sustainable large-scale biomass production. Its compelling characteristics included the recycling of nutrients and water resources, reducing carbon emissions and harvesting available biomass. In outdoor batch and continuous cultures, Chlorella pyrenoidosa completely adapted to anaerobic digested starch processing wastewater and was the dominant microorganism in the photobioreactor. However, seasonal changes of environmental conditions significantly influenced biomass growth and lipid production. The long-term outdoor operation demonstrated that the biomass concentration and productivity in continuous operations at different hydraulic retention times (HRTs) can be successfully predicted using the kinetic growth parameters obtained from the batch culture. A moderate HRT (4days) in the summer provided the best microalgae and lipid production and achieved relatively high biomass concentrations of 1.29-1.62g/L, biomass productivities of 342.6±12.8mg/L/d and lipids productivities of 43.37±7.43mg/L/d. PMID:25746477

  20. Ubiquitous anaerobic ammonium oxidation in inland waters of China: an overlooked nitrous oxide mitigation process

    NASA Astrophysics Data System (ADS)

    Zhu, Guibing; Wang, Shanyun; Zhou, Leiliu; Wang, Yu; Zhao, Siyan; Xia, Chao; Wang, Weidong; Zhou, Rong; Wang, Chaoxu; Jetten, Mike S. M.; Hefting, Mariet M.; Yin, Chengqing; Qu, Jiuhui

    2015-11-01

    Denitrification has long been regarded as the only pathway for terrestrial nitrogen (N) loss to the atmosphere. Here we demonstrate that large-scale anaerobic ammonium oxidation (anammox), an overlooked N loss process alternative to denitrification which bypasses nitrous oxide (N2O), is ubiquitous in inland waters of China and contributes significantly to N loss. Anammox rates in aquatic systems show different levels (1.0-975.9 μmol N m-2 h-1, n = 256) with hotspots occurring at oxic-anoxic interfaces and harboring distinct biogeochemical and biogeographical features. Extrapolation of these results to the China-national level shows that anammox could contribute about 2.0 Tg N yr-1, which equals averagely 11.4% of the total N loss from China’s inland waters. Our results indicate that a significant amount of the nitrogen lost from inland waters bypasses denitrification, which is important for constructing more accurate climate models and may significantly reduce potential N2O emission risk at a large scale.

  1. Effects of thermo-chemical pre-treatment on anaerobic biodegradability and hydrolysis of lignocellulosic biomass.

    PubMed

    Fernandes, T V; Bos, G J Klaasse; Zeeman, G; Sanders, J P M; van Lier, J B

    2009-05-01

    The effects of different thermo-chemical pre-treatment methods were determined on the biodegradability and hydrolysis rate of lignocellulosic biomass. Three plant species, hay, straw and bracken were thermo-chemically pre-treated with calcium hydroxide, ammonium carbonate and maleic acid. After pre-treatment, the plant material was anaerobically digested in batch bottles under mesophilic conditions for 40 days. From the pre-treatment and subsequent anaerobic digestion experiments, it was concluded that when the lignin content of the plant material is high, thermo-chemical pre-treatments have a positive effect on the biodegradability of the substrate. Calcium hydroxide pre-treatment improves the biodegradability of lignocellulosic biomass, especially for high lignin content substrates, like bracken. Maleic acid generates the highest percentage of dissolved COD during pre-treatment. Ammonium pre-treatment only showed a clear effect on biodegradability for straw. PMID:19144515

  2. Treatment of anaerobic digester effluents of nylon wastewater through chemical precipitation and a sequencing batch reactor process.

    PubMed

    Huang, Haiming; Song, Qianwu; Wang, Wenjun; Wu, Shaowei; Dai, Jiankun

    2012-06-30

    Chemical precipitation, in combination with a sequencing batch reactor (SBR) process, was employed to remove pollutants from anaerobic digester effluents of nylon wastewater. The effects of the chemicals along with various Mg:N:P ratios on the chemical precipitation (struvite precipitation) were investigated. When brucite and H(3)PO(4) were applied at an Mg:N:P molar ratio of 3:1:1, an ammonia-removal rate of 81% was achieved, which was slightly more than that (80%) obtained with MgSO(4)·7H(2)O and Na(2)HPO(4)·12H(2)O at Mg:N:P molar ratios greater than the stoichiometric ratio. To further reduce the ammonia loads of the successive biotreatment, an overdose of phosphate with brucite and H(3)PO(4) was applied during chemical precipitation. The ammonia-removal rate at the Mg:N:P molar ratio of 3.5:1:1.05 reached 88%, with a residual PO(4)-P concentration of 16 mg/L. The economic analysis showed that the chemical cost of chemical precipitation could be reduced by about 41% when brucite and H(3)PO(4) were used instead of MgSO(4)·7H(2)O and Na(2)HPO(4)·12H(2)O. The subsequent biological process that used a sequencing batch reactor showed high removal rates of contaminants. The quality of the final effluent met the requisite effluent-discharging standards.

  3. Comprehensive microbial analysis of combined mesophilic anaerobic-thermophilic aerobic process treating high-strength food wastewater.

    PubMed

    Jang, Hyun Min; Ha, Jeong Hyub; Park, Jong Moon; Kim, Mi-Sun; Sommer, Sven G

    2015-04-15

    A combined mesophilic anaerobic-thermophilic aerobic process was used to treat high-strength food wastewater in this study. During the experimental period, most of solid residue from the mesophilic anaerobic reactor (R1) was separated by centrifugation and introduced into the thermophilic aerobic reactor (R2) for further digestion. Then, thermophilic aerobically-digested sludge was reintroduced into R1 to enhance reactor performance. The combined process was operated with two different Runs: Run I with hydraulic retention time (HRT) = 40 d (corresponding OLR = 3.5 kg COD/m(3) d) and Run II with HRT = 20 d (corresponding OLR = 7 kg COD/m(3)). For a comparison, a single-stage mesophilic anaerobic reactor (R3) was operated concurrently with same OLRs and HRTs as the combined process. During the overall digestion, all reactors showed high stability without pH control. The combined process demonstrated significantly higher organic matter removal efficiencies (over 90%) of TS, VS and COD and methane production than did R3. Quantitative real-time PCR (qPCR) results indicated that higher populations of both bacteria and archaea were maintained in R1 than in R3. Pyrosequencing analysis revealed relatively high abundance of phylum Actinobacteria in both R1 and R2, and a predominance of phyla Synergistetes and Firmicutes in R3 during Run II. Furthermore, R1 and R2 shared genera (Prevotella, Aminobacterium, Geobacillus and Unclassified Actinobacteria), which suggests synergy between mesophilic anaerobic digestion and thermophilic aerobic digestion. For archaea, in R1 methanogenic archaea shifted from genus Methanosaeta to Methanosarcina, whereas genera Methanosaeta, Methanobacterium and Methanoculleus were predominant in R3. The results demonstrated dynamics of key microbial populations that were highly consistent with an enhanced reactor performance of the combined process.

  4. Performance evaluation of upflow anaerobic sludge blanket reactor process for dairy wastewater treatment.

    PubMed

    Elangovan, C; Sekar, A S S

    2015-11-01

    Investigation on dairy wastewater treatment was undertaken at ambient temperature in 11 l effective volume of laboratory--scale upflow anaerobic sludge blanket reactor receiving an average influent chemical oxygen demand of 2100 mg 1(-1) for 3 months of 24 hours, hydraulic retention time. The feeds of the synthetic dairy wastewater operated with HRT of 12 hrs, 16 hrs, 20 hrs and 24 hrs was equivalent to organic loading rates of 1.20 kg COD m(-3) d-7.20 kg COD m(-3) d, 0.9 kg COD m(-3) d-5.40 kg COD m(-3) d, 0.72 kg COD m(-3) d--4.32 kg COD m(-3) d and 0.60 kg COD m(-3) d-3.60 kg COD m(-3) d respectively. After steady state condition was reached, which took about 2 months, the effluent quality parameter were sampled and analysed to quantify treatment efficiencies. The following removal efficiency observed were 73-94.33% COD; 50.04- 56.66% total solids; 45.55-70.63% total dissolved solids; 66-86.67% total nitrogen and 72-94% total phosphorous. Maximum biogas production rate was 383 l kg(-1) COD removed with 260 l of methane gas. Estimation of biogas production was analysed using artificial neural network software model, and the results predicted coincided well with the experimental results. PMID:26688965

  5. The effects of different mixing intensities during anaerobic digestion of the organic fraction of municipal solid waste

    SciTech Connect

    Lindmark, Johan Eriksson, Per; Thorin, Eva

    2014-08-15

    Highlights: • Effects of mixing on the anaerobic digestion of municipal solid waste. • Digestion of fresh substrate and post-digestion at three mixing intensities were evaluated. • Mixing performed at 150 RPM, 25 RPM and minimally intermittently. • Increased biogas production rates and yields at lower mixing intensities. - Abstract: Mixing inside an anaerobic digester is often continuous and is not actively controlled. The selected mixing regime can however affect both gas production and the energy efficiency of the biogas plant. This study aims to evaluate these effects and compare three different mixing regimes, 150 RPM and 25 RPM continuous mixing and minimally intermittent mixing for both digestion of fresh substrate and post-digestion of the organic fraction of municipal solid waste. The results show that a lower mixing intensity leads to a higher biogas production rate and higher total biogas production in both cases. 25 RPM continuous mixing and minimally intermittent mixing resulted in similar biogas production after process stabilization, while 150 RPM continuous mixing resulted in lower production throughout the experiment. The lower gas production at 150 RPM could not be explained by the inhibition of volatile fatty acids. Cumulative biogas production until day 31 was 295 ± 2.9, 317 ± 1.9 and 304 ± 2.8 N ml/g VS added during digestion of fresh feed and 113 ± 1.3, 134 ± 1.1 and 130 ± 2.3 N ml/g VS added during post digestion for the 150 RPM, 25 RPM and minimally mixed intensities respectively. As well as increasing gas production, optimal mixing can improve the energy efficiency of the anaerobic digestion process.

  6. Study of the diversity of microbial communities in a sequencing batch reactor oxic-settling-anaerobic process and its modified process.

    PubMed

    Sun, Lianpeng; Chen, Jianfan; Wei, Xiange; Guo, Wuzhen; Lin, Meishan; Yu, Xiaoyu

    2016-05-01

    To further reveal the mechanism of sludge reduction in the oxic-settling-anaerobic (OSA) process, the polymerase chain reaction - denaturing gradient gel electrophoresis protocol was used to study the possible difference in the microbial communities between a sequencing batch reactor (SBR)-OSA process and its modified process, by analyzing the change in the diversity of the microbial communities in each reactor of both systems. The results indicated that the structure of the microbial communities in aerobic reactors of the 2 processes was very different, but the predominant microbial populations in anaerobic reactors were similar. The predominant microbial population in the aerobic reactor of the SBR-OSA belonged to Burkholderia cepacia, class Betaproteobacteria, while those of the modified process belonged to the classes Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria. These 3 types of microbes had a cryptic growth characteristic, which was the main cause of a greater sludge reduction efficiency achieved by the modified process. PMID:27021584

  7. Evaluation of sludge reduction by an environmentally friendly chemical uncoupler in a pilot-scale anaerobic/anoxic/oxic process.

    PubMed

    Guo, Xuesong; Yang, Jianming; Liang, Yuan; Liu, Junxin; Xiao, Benyi

    2014-03-01

    An environmentally friendly chemical, tetrakis(hydroxymethyl)phosphonium sulfate (THPS), was used as a metabolic uncoupler to reduce sludge production in a pilot-scale anaerobic/anoxic/oxic process. The results show that the addition of THPS (1.08-1.86 mL/m(3) influent) in the sludge return section could reduce waste activated sludge by about 22.5 %, and decrease the sludge yield by about 14.7 % at the end of a run. At the same time, the addition of THPS slightly lowered the removal of chemical oxygen demand (COD), soluble COD and NH4 (+)-N, and slightly improved removal of total nitrogen. The effects of THPS addition on two characteristics of activated sludge in oxic tank are discussed in detail and the results suggest that the settleability of sludge was reduced by addition of THPS, while the specific oxygen uptake rate was increased. Molecular biology analysis shows that the addition of THPS had little effect on the microbial communities of sludge.

  8. Two-phase thermophilic anaerobic digestion process for biohythane production treating biowaste: preliminary results.

    PubMed

    Cavinato, C; Bolzonella, D; Fatone, F; Giuliano, A; Pavan, P

    2011-01-01

    This paper deals with the optimization of a two-phase anaerobic process treating biowaste for hydrogen and methane production. Neither physical nor chemical pre-treatments were used to optimize the process. The work was carried out at pilot scale, using two CSTRs (200 and 380 L working volume respectively) both maintained at thermophilic temperature (55 C) and fed semi-continuously with biowaste. The experiment was divided into three periods; during the first two periods the organic loading rate was maintained at 20 kg TVS/m3 d and the hydraulic retention time was changed from 6.6 to 3.3 days, while in the last period the digestate of the second reactor was recirculated to the first reactor in order to buffer the system and control pH at levels around 5. The HRT was maintained at 3.3 days and the OLR was decreased at 16.5 kg TVS/m3 d. The best yield was obtained in the last period where a specific hydrogen production of 50.9 L/kg VSfed was reached, with a H2 content in biogas from the first reactor of 36%. The methanogenic stage after the hydrogen conversion reached a specific biogas production of 0.62 m3/kg VSfed and an overall organic removal above 70%, without any stability problem. The overall biogas production was some 1.5 m3 per day with a gas composition of 10% H2 and 50% CH4. PMID:22097052

  9. Metabolic and microbial community dynamics during the anaerobic digestion of maize silage in a two-phase process.

    PubMed

    Sträuber, Heike; Lucas, Rico; Kleinsteuber, Sabine

    2016-01-01

    Two-phasic anaerobic digestion processes (hydrolysis/acidogenesis separated from acetogenesis/methanogenesis) can be used for biogas production on demand or a combined chemicals/bioenergy production. For an effective process control, detailed knowledge about the microbial catalysts and their correlation to process conditions is crucial. In this study, maize silage was digested in a two-phase process and interrelationships between process parameters and microbial communities were revealed. In the first-phase reactor, alternating metabolic periods were observed which emerged independently from the feeding frequency. During the L-period, up to 11.8 g L(-1) lactic acid was produced which significantly correlated to lactic acid bacteria of the genus Lactobacillus as the most abundant community members. During the alternating G-period, the production of volatile fatty acids (up to 5.3, 4.0 and 3.1 g L(-1) for propionic, n-butyric and n-caproic acid, respectively) dominated accompanied by a high gas production containing up to 28 % hydrogen. The relative abundance of various Clostridiales increased during this metabolic period. In the second-phase reactor, the metabolic fluctuations of the first phase were smoothed out resulting in a stable biogas production as well as stable bacterial and methanogenic communities. However, the biogas composition followed the metabolic dynamics of the first phase: the hydrogen content increased during the L-period whereas highest CH4/CO2 ratios (up to 2.8) were reached during the G-period. Aceticlastic Methanosaeta as well as hydrogenotrophic Methanoculleus and Methanobacteriaceae were identified as dominant methanogens. Consequently, a directed control of the first-phase stabilizing desired metabolic states can lead to an enhanced productivity regarding chemicals and bioenergy.

  10. Stable isotope composition of biogas allows early warning of complete process failure as a result of ammonia inhibition in anaerobic digesters.

    PubMed

    Lv, Zuopeng; Hu, Meng; Harms, Hauke; Richnow, Hans Hermann; Liebetrau, Jan; Nikolausz, Marcell

    2014-09-01

    Four 15-L lab-scale continuous stirred tank reactors were operated under mesophilic conditions to investigate the effect of ammonia inhibition. Stable isotope fingerprinting of biogas was applied as a process monitoring tool. Ammonia inhibition was initiated by amendment of chicken manure to maize silage fed reactors. During the accumulation of ammonia, the concentration of volatile fatty acids increased while the biogas production and pH decreased. However, in one reactor, an inhibited steady state with stable gas production even at high ammonia levels was achieved, while the other reactor proceeded to complete process failure. A depletion of the δ(13)CH4 and δ(13)CO2 values preceded the process inhibition. Moreover, the stable isotope composition of biogas also forecasted the complete process failure earlier than other standard parameters. The stable isotope analyses of biogas have a potential for mechanistic insights in anaerobic processes, and may be used to pre-warn process failure under stress conditions.

  11. Anaerobic biodegradability and inhibitory effects of some anionic and cationic surfactants.

    PubMed

    Pérez-Armendáriz, Beatriz; Moreno, Yésica Mayett; Monroy-Hermosillo, Oscar; Guyot, Jean Pierre; González, Rosa O

    2010-09-01

    The anaerobic biodegradability and inhibitory effects on the methane production of three different surfactants, two anionic: sodium lauryl sulfate (SLS) and sodium dodecylbenzene sulfonate (SDBS), and a cationic surfactant: trialkyl-methylammonium chloride (TMAC), were evaluated with two different anaerobic sludges, granular and flocculent. Five different concentrations of the surfactants, 5, 50, 100, 250 and 500 mg/L, were tested. SLS was biodegraded at concentrations of 5, 50 and 100 mg/L with flocculent sludge and at 100 and 250 mg/L with granular sludge. However an inhibitory effect on methane production was observed in both sludges at 500 mg/L. The results indicate that SDBS was not biodegradable under anoxic conditions. TMAC was slightly degraded 50 and 100 mg/L with the flocculent sludge, and from 100 to 500 mg/L with the granular sludge.

  12. Effect of temperature and temperature fluctuation on thermophilic anaerobic digestion of cattle manure.

    PubMed

    El-Mashad, Hamed M; Zeeman, Grietje; van Loon, Wilko K P; Bot, Gerard P A; Lettinga, Gatze

    2004-11-01

    The influence of temperature, 50 and 60 degrees C, at hydraulic retention times (HRTs) of 20 and 10 days, on the performance of anaerobic digestion of cow manure has been investigated in completely stirred tank reactors (CSTRs). Furthermore, the effect of both daily downward and daily upward temperature fluctuations has been studied. In the daily downward temperature fluctuation regime the temperatures of each reactor was reduced by 10 degrees C for 10 h while in the daily upward fluctuation regime the temperature of each reactor was increased 10 degrees C for 5 h. The results show that the methane production rate at 60 degrees C is lower than that at 50 degrees C at all experimental conditions of imposed HRT except when downward temperature fluctuations were applied at an HRT of 10 days. It also was found that the free ammonia concentration not only affects the acetate-utilising bacteria but also the hydrolysis and acidification process. The upward temperature fluctuation affects the maximum specific methanogenesis activity more severely as compared to imposed downward temperature fluctuations. The results clearly reveal the possibility of using available solar energy at daytime to heat up the reactor(s) without the need of heat storage during nights, especially at an operational temperature of 50 degrees C and at a 20 days HRT, and without the jeopardising of the overheating. PMID:15246444

  13. Effect of temperature and temperature fluctuation on thermophilic anaerobic digestion of cattle manure.

    PubMed

    El-Mashad, Hamed M; Zeeman, Grietje; van Loon, Wilko K P; Bot, Gerard P A; Lettinga, Gatze

    2004-11-01

    The influence of temperature, 50 and 60 degrees C, at hydraulic retention times (HRTs) of 20 and 10 days, on the performance of anaerobic digestion of cow manure has been investigated in completely stirred tank reactors (CSTRs). Furthermore, the effect of both daily downward and daily upward temperature fluctuations has been studied. In the daily downward temperature fluctuation regime the temperatures of each reactor was reduced by 10 degrees C for 10 h while in the daily upward fluctuation regime the temperature of each reactor was increased 10 degrees C for 5 h. The results show that the methane production rate at 60 degrees C is lower than that at 50 degrees C at all experimental conditions of imposed HRT except when downward temperature fluctuations were applied at an HRT of 10 days. It also was found that the free ammonia concentration not only affects the acetate-utilising bacteria but also the hydrolysis and acidification process. The upward temperature fluctuation affects the maximum specific methanogenesis activity more severely as compared to imposed downward temperature fluctuations. The results clearly reveal the possibility of using available solar energy at daytime to heat up the reactor(s) without the need of heat storage during nights, especially at an operational temperature of 50 degrees C and at a 20 days HRT, and without the jeopardising of the overheating.

  14. Effect of heating strategy on power consumption and performance of a pilot plant anaerobic digester.

    PubMed

    Espinosa-Solares, Teodoro; Valle-Guadarrama, Salvador; Bombardiere, John; Domaschko, Max; Easter, Michael

    2009-05-01

    The effect of heating strategy on power consumption and performance of a pilot plant anaerobic digester treating chicken litter, under thermophilic conditions, has been studied. Heating strategy was evaluated using three different spans (0.2 degrees C, 0.6 degrees C, and 1.0 degree C) for triggering the temperature control system from target temperature (56.7 degrees C). The hydraulic retention time in the pilot plant digester was in the range of 32 to 37 days, varying the total solids concentration fed from 5% to 6%. The results showed that under the experimental conditions, heating was the most energy-demanding process with 95.5% of the energy used. Increments up to 7.5% and 3.8%, respectively, on mechanical and heating power consumption, were observed as the span, for triggering the temperature control system from target temperature, was increased. Under the experimental conditions studied here, an increment of 30.6% on the global biodigester performance index was observed when a span of 1.0 degree C was compared to the one of 0.2 degrees C.

  15. Effect of temperature on the treatment of domestic wastewater with a staged anaerobic fluidized membrane bioreactor.

    PubMed

    Yoo, R H; Kim, J H; McCarty, P L; Bae, J H

    2014-01-01

    A laboratory staged anaerobic fluidized membrane bioreactor (SAF-MBR) system was applied to the treatment of primary clarifier effluent from a domestic wastewater treatment plant with temperature decreasing from 25 to 10 °C. At all temperatures and with a total hydraulic retention time of 2.3 h, overall chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) removals were 89% and 94% or higher, with permeate COD and BOD5 of 30 and 7 mg/L or lower, respectively. No noticeable negative effects of low temperature on organic removal were found, although a slight increase to 3 mg/L in volatile fatty acids concentrations in the effluent was observed. Biosolids production was 0.01-0.03 kg volatile suspended solids/kg COD, which is far less than that with aerobic processes. Although the rate of trans-membrane pressure at the membrane flux of 9 L/m(2)/h increased as temperature decreased, the SAF-MBR was operated for longer than 200 d before chemical cleaning was needed. Electrical energy potential from combustion of the total methane production (gaseous and dissolved) was more than that required for system operation.

  16. Treatment process and toxicities assessment of wastewater issued from anaerobic digestion of household wastes.

    PubMed

    Djelal, Hayet; Tahrani, Leyla; Fathallah, Salem; Cabrol, Audrey; Mansour, Hedi Ben

    2014-02-01

    Modern society grapples with large amounts of household waste. The anaerobic digestion of this waste offers a promising source for energy-rich biogas production but generates high toxic effluents that require treatment before reuse or disposal into the environment. This study aimed to investigate three techniques, namely coagulation/flocculation, electro-coagulation, and activated sludge, in terms of efficiency in the treatment of these effluents. It also aimed to assess their toxicity effects on the germination and growth of durum wheat Triticum aestivum L. seeds before and after 6 days of treatment. Activated sludge was most efficient in reducing chemical oxygen demand, turbidity, and conductivity (95.7 %, 15.8 %, and 37.5 %, respectively). The effluent treated with this technique induced a marked delay in germination (low mean time of germination) and a significant reduction in the percentages of seed germination and root and leaf growths. It was also noted to strongly induce lipid peroxidation in roots and leaves, which presumably explained the germination/growth inhibition of the wheat seeds. The effluent also induced marked lipid peroxidation effects and strongly inhibited the activities of butyrylcholinesterase in mice bone marrows. The effluent shows a high ability to inhibit the growth of three microalgae; these endpoints are useful tools to biomonitor the physico-chemical quality of this wastewater. Overall, while no significant alterations were observed in terms of animal and vegetable toxicities when the effluent was treated by coagulation/flocculation, activated sludge treatment proved efficient in reducing the toxicities induced by the untreated effluents. The results indicate that the application of this technique is promising with regards to attaining efficient, eco-friendly, and cost-effective strategies for the management and treatment of household waste. PMID:24072641

  17. Treatment process and toxicities assessment of wastewater issued from anaerobic digestion of household wastes.

    PubMed

    Djelal, Hayet; Tahrani, Leyla; Fathallah, Salem; Cabrol, Audrey; Mansour, Hedi Ben

    2014-02-01

    Modern society grapples with large amounts of household waste. The anaerobic digestion of this waste offers a promising source for energy-rich biogas production but generates high toxic effluents that require treatment before reuse or disposal into the environment. This study aimed to investigate three techniques, namely coagulation/flocculation, electro-coagulation, and activated sludge, in terms of efficiency in the treatment of these effluents. It also aimed to assess their toxicity effects on the germination and growth of durum wheat Triticum aestivum L. seeds before and after 6 days of treatment. Activated sludge was most efficient in reducing chemical oxygen demand, turbidity, and conductivity (95.7 %, 15.8 %, and 37.5 %, respectively). The effluent treated with this technique induced a marked delay in germination (low mean time of germination) and a significant reduction in the percentages of seed germination and root and leaf growths. It was also noted to strongly induce lipid peroxidation in roots and leaves, which presumably explained the germination/growth inhibition of the wheat seeds. The effluent also induced marked lipid peroxidation effects and strongly inhibited the activities of butyrylcholinesterase in mice bone marrows. The effluent shows a high ability to inhibit the growth of three microalgae; these endpoints are useful tools to biomonitor the physico-chemical quality of this wastewater. Overall, while no significant alterations were observed in terms of animal and vegetable toxicities when the effluent was treated by coagulation/flocculation, activated sludge treatment proved efficient in reducing the toxicities induced by the untreated effluents. The results indicate that the application of this technique is promising with regards to attaining efficient, eco-friendly, and cost-effective strategies for the management and treatment of household waste.

  18. Effect of the chlortetracycline addition method on methane production from the anaerobic digestion of swine wastewater.

    PubMed

    Huang, Lu; Wen, Xin; Wang, Yan; Zou, Yongde; Ma, Baohua; Liao, Xindi; Liang, Juanboo; Wu, Yinbao

    2014-10-01

    Effects of antibiotic residues on methane production in anaerobic digestion are commonly studied using the following two antibiotic addition methods: (1) adding manure from animals that consume a diet containing antibiotics, and (2) adding antibiotic-free animal manure spiked with antibiotics. This study used chlortetracycline (CTC) as a model antibiotic to examine the effects of the antibiotic addition method on methane production in anaerobic digestion under two different swine wastewater concentrations (0.55 and 0.22mg CTC/g dry manure). The results showed that CTC degradation rate in which manure was directly added at 0.55mg CTC/g (HSPIKE treatment) was lower than the control values and the rest of the treatment groups. Methane production from the HSPIKE treatment was reduced (p<0.05) by 12% during the whole experimental period and 15% during the first 7days. The treatments had no significant effect on the pH and chemical oxygen demand value of the digesters, and the total nitrogen of the 0.55mg CTC/kg manure collected from mediated swine was significantly higher than the other values. Therefore, different methane production under different antibiotic addition methods might be explained by the microbial activity and the concentrations of antibiotic intermediate products and metabolites. Because the primary entry route of veterinary antibiotics into an anaerobic digester is by contaminated animal manure, the most appropriate method for studying antibiotic residue effects on methane production may be using manure from animals that are given a particular antibiotic, rather than adding the antibiotic directly to the anaerobic digester.

  19. Effect of chlorate, molybdate, and shikimic acid on Salmonella Typhimurium in aerobic and anaerobic cultures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two studies were conducted to examine the effects of shikimic acid (60 µg/mL) and(or) molybdate (1 mM) on the sensitivity of Salmonella enterica serovar Typhimurium to sodium chlorate (5 mM) during anaerobic (90% N2:5% CO2:5% H2) or aerobic growth in brain heart infusion broth supplemented with 5 mM...

  20. Effects of mixing on methane production during thermophilic anaerobic digestion of manure: lab-scale and pilot-scale studies.

    PubMed

    Kaparaju, Prasad; Buendia, Inmaculada; Ellegaard, Lars; Angelidakia, Irini

    2008-07-01

    The effect of mixing on anaerobic digestion of manure was evaluated in lab-scale and pilot-scale experiments at 55 degrees C. The effect of continuous (control), minimal (mixing for 10 min prior to extraction/feeding) and intermittent mixing (withholding mixing for 2h prior to extraction/feeding) on methane production was investigated in three lab-scale continuously stirred tank reactors. On comparison to continuous mixing, intermittent and minimal mixing strategies improved methane productions by 1.3% and 12.5%, respectively. Pilot-scale studies also supported the lab-scale results with an average 7% increase in biogas yields during intermittent mixing compared to continuous mixing. The effect of mixing intensities (minimal, gentle or vigorous) in batch assays at 55 degrees C showed that when the process was overloaded by high substrate to inoculum ratio (40/60), gentle (35 times per minute) or minimal mixing (10 min mixing before feeding) was advantageous compared to vigorous mixing (110 times per minute). On the other hand, under low substrate to inoculum ratio (10/90), gentle mixing was the best. The study thus indicated that mixing schemes and intensities have some effect on anaerobic digestion of manures.

  1. Gas-liquid chromatography in routine processing of blood cultures for detecting anaerobic bacteraemia.

    PubMed Central

    Reig, M; Molina, D; Loza, E; Ledesma, M A; Meseguer, M A

    1981-01-01

    Gas-liquid chromatography was performed on 233 positive blood cultures and findings were compared with culture results. Obligate anaerobic bacteria were recovered from 78 out of 79 blood cultures containing butyric or iso-valeric acids, or both; from 28 out of 69 blood cultures containing succinic acid; and from only one out of 41 blood cultures containing succinic but not butyric or iso-valeric acid. Good correlations (88%) were found for the recovery of anaerobic bacteria and the detection of butyric and/or iso-valeric acids. Detecting volatile fatty acids by gas-liquid chromatography performed on blood cultures at the first signs of growth can therefore provide an early and reliable indication of the presence of anaerobic bacteria. PMID:7014645

  2. Impacts of trace element supplementation on the performance of anaerobic digestion process: A critical review.

    PubMed

    Choong, Yee Yaw; Norli, Ismail; Abdullah, Ahmad Zuhairi; Yhaya, Mohd Firdaus

    2016-06-01

    This paper critically reviews the impacts of supplementing trace elements on the anaerobic digestion performance. The in-depth knowledge of trace elements as micronutrients and metalloenzyme components justifies trace element supplementation into the anaerobic digestion system. Most of the earlier studies reported that trace elements addition at (sub)optimum dosages had positive impacts mainly longer term on digester stability with greater organic matter degradation, low volatile fatty acids (VFA) concentration and higher biogas production. However, these positive impacts and element requirements are not fully understood, they are explained on a case to case basis because of the great variance of the anaerobic digestion operation. Iron (Fe), nickel (Ni) and cobalt (Co) are the most studied and desirable elements. The right combination of multi-elements supplementation can have greater positive impact. This measure is highly recommended, especially for the mono-digestion of micronutrient-deficient substrates. The future research should consider the aspect of trace element bioavailability.

  3. Degradation of oleic acid in anaerobic filters: the effect of inoculum acclimatization and biomass recirculation.

    PubMed

    Pereira, A; Mota, M; Alves, M

    2001-01-01

    The degradation of oleic acid in anaerobic filters was studied and the effect of an acclimated inoculum and biomass recirculation was evaluated. Three anaerobic filters (R1, R2, and R3) were operated in parallel. The anaerobic filters R1 and R2 were inoculated with nonacclimated biomass, whereas the anaerobic filter R3 was inoculated with acclimated biomass. In the anaerobic filters R2 and R3, biomass settling and recirculation were applied. The use of an acclimated inoculum and biomass recirculation (R3) was beneficial in terms of removal efficiency, which was 4 to 8% higher than in the anaerobic filters R1 and R2 when oleate was the sole carbon source fed to the reactors at an applied organic load of 12.5 kg of chemical oxygen demand (COD)/m3 x d, even with an oleate to calcium and magnesium ion molar concentration ratio of 6.8. Biomass recirculation significantly reduced the biomass washout and the toxic effect on the acetogenic and methanogenic populations. The use of an acclimated inoculum was beneficial in terms of methane yield, which was 50% greater than that observed for the reactors inoculated with nonacclimated inoculum for the highest applied organic loading rate (12.5 kg COD/m3 x d). At the end of the operation, the biomass was encapsulated by a whitish matter, which was well detected by microscopic examination. When this sludge was incubated in batch vials at 37 degrees C where no substrate was added, methane production from the adsorbed organic matter was evidenced, attaining a maximum value (at standard temperature and pressure) of 39.7 mL/g volatile solids x d for the biomass taken from R1. With stirring (150 r/min), the methane production rate was 13.8 times higher than under static conditions. When oleate was added to this sludge, methane production was delayed, suggesting that adsorbed matter can be an intermediate of oleate degradation such as stearic, palmitic, myristic, or other saturated acids.

  4. Start-up of an anaerobic/oxic process for phosphorus removal at the Northwest Quadrant Wastewater Treatment Plant. Final report

    SciTech Connect

    Not Available

    1992-08-01

    This study investigated the suitability and effectiveness of a proprietary anaerobic/oxic (A/0) process to facilitate the biological removal of phosphorus from domestic wastewater. The study took place at the Northwest Quadrant Wastewater Treatment Plant in Hilton, New York, and was conducted in conjunction with the New York State Energy Research & Development Authority (the Energy Authority) and the Monroe County Department of Pure Waters. The NWQWWTP concentration limit for total effluent phosphorus is 1.0 mg/l. Influent phosphorus concentrations usually vary from 4 to 5 mg/l at the plant.

  5. Anaerobic digestion of different feedstocks: impact on energetic and environmental balances of biogas process.

    PubMed

    Bacenetti, Jacopo; Negri, Marco; Fiala, Marco; González-García, Sara

    2013-10-01

    The possibility of limiting the global warming is strictly linked to the reduction of GHG emissions. Renewable energy both allows reducing emissions and permits to delay fossil fuel depletion. The anaerobic digestion of animal manure and energy crops is a promising way of reducing GHG emissions. In Italy agricultural biogas production was considerably increased; nowadays there are about 520 agricultural biogas plants. The increasing number of biogas plants, especially of those larger than 500 kW(e) (electrical power), involves a high consumption of energy crops, large transport distances of biomass and digestate and difficulties on thermal energy valorization. In this study the energetic (CED) and environmental (GHG emissions) profiles associated with the production of electricity derived from biogas have been identified. Three biogas plants located in Northern Italy have been analyzed. The study has been carried out considering a cradle-to-grave perspective and thus, special attention has been paid on the feedstock production and biogas production process. The influences on the results taking into account different plant sizes and feeding rate has been assessed in detail. Energy analysis was performed using the Cumulative Energy Demand method (CED). The climate change was calculated for a 100-year time frame based on GHG emissions indicated as CO2 equivalents (eq) and defined by the IPCC (2006). In comparison to the fossil reference system, the electricity production using biogas saves GHG emissions from 0.188 to 1.193 kg CO2eq per kWh(e). Electricity supply from biogas can also contribute to a considerable reduction of the use of fossil energy carriers (from -3.97 to 10.08 MJ(fossil) per kWh(e)). The electricity production from biogas has a big potential for energy savings and reduction of GHG emissions. Efficient utilization of the cogenerated heat can substantially improve the GHG balance of electricity production from biogas.

  6. Simple, rapid and effective preservation and reactivation of anaerobic ammonium oxidizing bacterium "Candidatus Brocadia sinica".

    PubMed

    Ali, Muhammad; Oshiki, Mamoru; Okabe, Satoshi

    2014-06-15

    It is still the biggest challenge to secure enough seeding biomass for rapid start-up of full-scale (anaerobic ammonium oxidation) anammox processes due to slow growth. Preservation of active anammox biomass could be one of the solutions. In this study, biomass of anammox bacterium, "Candidatus Brocadia sinica", immersed in various nutrient media were preserved at -80 °C, 4 °C and room temperature. After 45, 90 and 150 days of preservation, specific anammox activity (SAA) of the preserved anammox biomass was determined by measuring (29)N2 production rate and transcription levels of hzsA gene encoding hydrazine synthase alpha subunit. Storage in nutrient medium containing 3 mM of molybdate at room temperature with periodical (every 45 days) supply of NH4(+) and NO2(-) was proved to be the most effective storage technique for "Ca. Brocadia sinica" biomass. Using this preservation condition, 96, 92 and 65% of the initial SAA was sustained after 45, 90 and 150 days of storage, respectively. Transcription levels of hzsA gene in biomass correlated with the SAA (R(2) = 0.83), indicating it can be used as a genetic marker to evaluate the anammox activity of preserved biomass. Furthermore, the 90-day-stored biomass was successfully reactivated by immobilizing in polyvinyl alcohol (6%, w/v) and sodium alginate (2%, w/v) gel and then inoculated to up-flow column reactors. Total nitrogen removal rates rapidly increased to 7 kg-N m(-3) d(-1) within 35 days of operation. Based on these results, the room temperature preservation with molybdate addition is simple, cost-effective and feasible at a practical scale, which will accelerate the practical use of anammox process for wastewater treatment.

  7. Simple, rapid and effective preservation and reactivation of anaerobic ammonium oxidizing bacterium "Candidatus Brocadia sinica".

    PubMed

    Ali, Muhammad; Oshiki, Mamoru; Okabe, Satoshi

    2014-06-15

    It is still the biggest challenge to secure enough seeding biomass for rapid start-up of full-scale (anaerobic ammonium oxidation) anammox processes due to slow growth. Preservation of active anammox biomass could be one of the solutions. In this study, biomass of anammox bacterium, "Candidatus Brocadia sinica", immersed in various nutrient media were preserved at -80 °C, 4 °C and room temperature. After 45, 90 and 150 days of preservation, specific anammox activity (SAA) of the preserved anammox biomass was determined by measuring (29)N2 production rate and transcription levels of hzsA gene encoding hydrazine synthase alpha subunit. Storage in nutrient medium containing 3 mM of molybdate at room temperature with periodical (every 45 days) supply of NH4(+) and NO2(-) was proved to be the most effective storage technique for "Ca. Brocadia sinica" biomass. Using this preservation condition, 96, 92 and 65% of the initial SAA was sustained after 45, 90 and 150 days of storage, respectively. Transcription levels of hzsA gene in biomass correlated with the SAA (R(2) = 0.83), indicating it can be used as a genetic marker to evaluate the anammox activity of preserved biomass. Furthermore, the 90-day-stored biomass was successfully reactivated by immobilizing in polyvinyl alcohol (6%, w/v) and sodium alginate (2%, w/v) gel and then inoculated to up-flow column reactors. Total nitrogen removal rates rapidly increased to 7 kg-N m(-3) d(-1) within 35 days of operation. Based on these results, the room temperature preservation with molybdate addition is simple, cost-effective and feasible at a practical scale, which will accelerate the practical use of anammox process for wastewater treatment. PMID:24726991

  8. Acidification of In-Storage-Psychrophilic-Anaerobic-Digestion (ISPAD) process to reduce ammonia volatilization: Model development and validation.

    PubMed

    Madani-Hosseini, Mahsa; Mulligan, Catherine N; Barrington, Suzelle

    2016-06-01

    In-Storage-Psychrophilic-Anaerobic-Digestion (ISPAD) is an ambient temperature treatment system for wastewaters stored for over 100days under temperate climates, which produces a nitrogen rich digestate susceptible to ammonia (NH3) volatilization. Present acidification techniques reducing NH3 volatilization are not only expensive and with secondary environmental effects, but do not apply to ISPAD relying on batch-to-batch inoculation. The objectives of this study were to identify and validate sequential organic loading (OL) strategies producing imbalances in acidogen and methanogen growth, acidifying ISPAD content one week before emptying to a pH of 6, while also preserving the inoculation potential. This acidification process is challenging as wastewaters often offer a high buffering capacity and ISPAD operational practices foster low microbial populations. A model simulating the ISPAD pH regime was used to optimize 3 different sequential OLs to decrease the ISPAD pH to 6.0. All 3 strategies were compared in terms of biogas production, volatile fatty acid (VFA) concentration, microbial activity, glucose consumption, and pH decrease. Laboratory validation of the model outputs confirmed that a sequential OL of 13kg glucose/m(3) of ISPAD content over 4days could indeed reduce the pH to 6.0. Such OL competes feasibly with present acidification techniques. Nevertheless, more research is required to explain the 3-day lag between the model results and the experimental data. PMID:27060886

  9. Effect of digestion time on anaerobic digestion with high ammonia concentration

    NASA Astrophysics Data System (ADS)

    Oktavitri, Nur Indradewi; Purnobasuki, Hery; Kuncoro, Eko Prasetyo; Purnamasari, Indah; Semma Hadinnata, P.

    2016-03-01

    Anaerobic digestion was developed to treat high concentration organic compound efficiently in certain Digestion Time (DT). High ammonia concentration could influenced removal organic compound in digestion. This bench scale study investigated the effect of digestion time on anaerobic batch reactor with high ammonia concentration. Total Ammonia Nitrogen (TAN) concentration was adjusted 4000 and 5000 mg/1, Digestion time was ranged from 0-26 d, operation temperature was ranged from 28-29°C, inoculum was collected from slaughter house sludge. The degradation of Chemical Oxygen Demand (COD) correlated with digestion time. The concentration of TAN from synthetic wastewater contain 5000 mg/1 of TAN more fluctuated than those use 4000 mg/1 of TAN. However, the biogas production from wastewater contained 4000 mg/1 of TAN gradually increased until 24 d of DT. The reactor contain 5000 mg/1 of TAN only growth until 12 d and steady state at over 12 d of digestion time.

  10. Effect of different carbon materials as electron shuttles in the anaerobic biotransformation of nitroanilines.

    PubMed

    Pereira, Luciana; Pereira, Raquel; Pereira, Manuel F R; Alves, Madalena M

    2016-06-01

    Aromatic amines resulted from azo dyes biotransformation under anaerobic conditions are generally recalcitrant to further anaerobic degradation. The catalytic effect of carbon materials (CM) on the reduction of azo dyes is known and has been confirmed in this work by increasing threefold the biological reduction rate of Mordant Yellow 1 (MY1). The resulting m-nitroaniline (m-NoA) was further degraded to m-phenylenediamine (m-Phe) only in the presence of CM. The use of CM to degraded anaerobically aromatic amines resulted from azo dye reduction was never reported before. In the sequence, we studied the effect of different CM on the bioreduction of o-, m-, and p-NoA. Three microporous activated carbons with different surface chemistry, original (AC0 ), chemical oxidized with HNO3 (ACHNO3 ), and thermal treated (ACH2 ), and three mesoporous carbons, xerogels (CXA and CXB) and nanotubes (CNT) were assessed. In the absence of CM, NoA were only partially reduced to the corresponding Phe, whereas in the presence of CM, more than 90% was converted to the corresponding Phe. ACH2 and AC0 were the best electron shuttles, increasing the rates up to eightfold. In 24 h, the biological treatment of NoA and MY1 with AC0 , decreased up to 88% the toxicity towards a methanogenic consortium, as compared to the non-treated solutions. Biotechnol. Bioeng. 2016;113: 1194-1202. © 2015 Wiley Periodicals, Inc. PMID:26614891

  11. Effects of Predation by Protists on Prokaryotic Community Function, Structure, and Diversity in Anaerobic Granular Sludge

    PubMed Central

    Hirakata, Yuga; Oshiki, Mamoru; Kuroda, Kyohei; Hatamoto, Masashi; Kubota, Kengo; Yamaguchi, Takashi; Harada, Hideki; Araki, Nobuo

    2016-01-01

    Predation by protists is top-down pressure that regulates prokaryotic abundance, community function, structure, and diversity in natural and artificial ecosystems. Although the effects of predation by protists have been studied in aerobic ecosystems, they are poorly understood in anoxic environments. We herein studied the influence of predation by Metopus and Caenomorpha ciliates—ciliates frequently found in anoxic ecosystems—on prokaryotic community function, structure, and diversity. Metopus and Caenomorpha ciliates were cocultivated with prokaryotic assemblages (i.e., anaerobic granular sludge) in an up-flow anaerobic sludge blanket (UASB) reactor for 171 d. Predation by these ciliates increased the methanogenic activities of granular sludge, which constituted 155% of those found in a UASB reactor without the ciliates (i.e., control reactor). Sequencing of 16S rRNA gene amplicons using Illumina MiSeq revealed that the prokaryotic community in the UASB reactor with the ciliates was more diverse than that in the control reactor; 2,885–3,190 and 2,387–2,426 operational taxonomic units (>97% sequence similarities), respectively. The effects of predation by protists in anaerobic engineered systems have mostly been overlooked, and our results show that the influence of predation by protists needs to be examined and considered in the future for a better understanding of prokaryotic community structure and function. PMID:27431197

  12. Effects of sulfide on the integration of denitrification with anaerobic digestion.

    PubMed

    Yin, Zhixuan; Xie, Li; Zhou, Qi

    2015-10-01

    The effects of sulfide on the integration of denitrification with anaerobic digestion using anaerobic effluents of cassava stillage as carbon source were investigated. Batch tests indicated that nitrate reduction efficiencies decreased from 96.5% to 15.8% as sulfide/nitrate (S/NO3(-)-N) ratios increased from 0.27 to 1.60. At low S/NO3(-)-N ratios (0.27-1.08) anaerobic acidogenesis was accelerated. Nitrate was reduced to nitrite via sulfur-based autotrophic denitrification, after which the formed nitrite and residual nitrate were converted to N2 via heterotrophic denitrification. Increases in the S/NO3(-)-N ratio (1.60) caused a shift (76.3%) in the nitrate reduction pathway from denitrification to dissimilatory nitrate reduction to ammonia (DNRA). Sulfide concentrations (S/NO3(-)-N ratio of 1.60) suppressed not only heterotrophic denitrification but also acidogenesis. The potentially toxic effect of sulfide on acid production was mitigated by its rapid oxidation to sulfur, allowing the recovery of acidogenesis. PMID:25801462

  13. Effects of Predation by Protists on Prokaryotic Community Function, Structure, and Diversity in Anaerobic Granular Sludge.

    PubMed

    Hirakata, Yuga; Oshiki, Mamoru; Kuroda, Kyohei; Hatamoto, Masashi; Kubota, Kengo; Yamaguchi, Takashi; Harada, Hideki; Araki, Nobuo

    2016-09-29

    Predation by protists is top-down pressure that regulates prokaryotic abundance, community function, structure, and diversity in natural and artificial ecosystems. Although the effects of predation by protists have been studied in aerobic ecosystems, they are poorly understood in anoxic environments. We herein studied the influence of predation by Metopus and Caenomorpha ciliates-ciliates frequently found in anoxic ecosystems-on prokaryotic community function, structure, and diversity. Metopus and Caenomorpha ciliates were cocultivated with prokaryotic assemblages (i.e., anaerobic granular sludge) in an up-flow anaerobic sludge blanket (UASB) reactor for 171 d. Predation by these ciliates increased the methanogenic activities of granular sludge, which constituted 155% of those found in a UASB reactor without the ciliates (i.e., control reactor). Sequencing of 16S rRNA gene amplicons using Illumina MiSeq revealed that the prokaryotic community in the UASB reactor with the ciliates was more diverse than that in the control reactor; 2,885-3,190 and 2,387-2,426 operational taxonomic units (>97% sequence similarities), respectively. The effects of predation by protists in anaerobic engineered systems have mostly been overlooked, and our results show that the influence of predation by protists needs to be examined and considered in the future for a better understanding of prokaryotic community structure and function.

  14. Diagnosis of the anaerobic reject water effects on WWTP operational characteristics as a precursor of bulking and foaming.

    PubMed

    Erdirençelebi, Dilek; Küçükhemek, Murat

    2015-01-01

    This study investigates the effects observed on operational parameters in a large and full-scale wastewater treatment plant subjected to anaerobic reject water (ARW) diversion off the main line for a 3-month period and further monitoring for a 2-year period. The plant's secondary unit consists of a two-stage plug-flow-modified Bardenpho process receiving wastewater from both municipal and industrial origins. As a result, ARW was found to have a direct effect on bulking in secondary clarifiers and foaming in anaerobic digesters (AD) despite its relatively small flow rate. During the cut-off period a highly stable sludge volume index at 80 mL g(-1) level was obtained in the secondary clarifiers, effluent suspended solids concentration was reduced and continuous feeding to AD was recovered. Sludge density increased in the thickeners during hot season. Secondary clarifiers showed good and stable settleability despite low dissolved oxygen, food/microorganism ratio and high sludge retention time and ammonium levels in the biological unit. The bulking and foaming effect was presented on the plant's internal flow balance. ARW needs serious consideration for elimination by appropriate technologies because of its high potential as a multi-dimensional pollutant source, not only as a carrier of nutrients but also as a possible carrier of filamentous bacteria, which might promote chronic seeding and retention in the system.

  15. Diagnosis of the anaerobic reject water effects on WWTP operational characteristics as a precursor of bulking and foaming.

    PubMed

    Erdirençelebi, Dilek; Küçükhemek, Murat

    2015-01-01

    This study investigates the effects observed on operational parameters in a large and full-scale wastewater treatment plant subjected to anaerobic reject water (ARW) diversion off the main line for a 3-month period and further monitoring for a 2-year period. The plant's secondary unit consists of a two-stage plug-flow-modified Bardenpho process receiving wastewater from both municipal and industrial origins. As a result, ARW was found to have a direct effect on bulking in secondary clarifiers and foaming in anaerobic digesters (AD) despite its relatively small flow rate. During the cut-off period a highly stable sludge volume index at 80 mL g(-1) level was obtained in the secondary clarifiers, effluent suspended solids concentration was reduced and continuous feeding to AD was recovered. Sludge density increased in the thickeners during hot season. Secondary clarifiers showed good and stable settleability despite low dissolved oxygen, food/microorganism ratio and high sludge retention time and ammonium levels in the biological unit. The bulking and foaming effect was presented on the plant's internal flow balance. ARW needs serious consideration for elimination by appropriate technologies because of its high potential as a multi-dimensional pollutant source, not only as a carrier of nutrients but also as a possible carrier of filamentous bacteria, which might promote chronic seeding and retention in the system. PMID:25746650

  16. Effect of solid-state NaOH pretreatment on methane production from thermophilic semi-dry anaerobic digestion of rose stalk.

    PubMed

    Liang, Yue-Gan; Cheng, Beijiu; Si, You-Bin; Cao, De-Ju; Li, Dao-Lin; Chen, Jian-Feng

    2016-01-01

    The effects of solid-state NaOH pretreatment on the efficiency of methane production from semi-dry anaerobic digestion of rose (Rosa rugosa) stalk were investigated at various NaOH loadings (0, 1, 2, and 4% (w/w)). Methane production, process stability and energy balance were analyzed. Results showed that solid-state NaOH pretreatment significantly improved biogas and methane yields of 30-day anaerobic digestion, with increases from 143.7 mL/g volatile solids (VS) added to 157.1 mL/g VS -192.1 mL/g VS added and from 81.8 mL/g VS added to 88.8 mL/g VS-117.7 mL/g VS added, respectively. Solid-state NaOH pretreatment resulted in anaerobic digestion with higher VS reduction and lower technical digestion time. The 4% NaOH-treated group had the highest methane yield of 117.7 mL/g VS added, which was 144% higher compared to the no NaOH-treated group, and the highest net energy recovery. Higher rate of lignocellulose breakage and higher process stability of anaerobic digestion facilitated methane production in the NaOH-pretreated groups. PMID:27332836

  17. Effect of solid-state NaOH pretreatment on methane production from thermophilic semi-dry anaerobic digestion of rose stalk.

    PubMed

    Liang, Yue-Gan; Cheng, Beijiu; Si, You-Bin; Cao, De-Ju; Li, Dao-Lin; Chen, Jian-Feng

    2016-01-01

    The effects of solid-state NaOH pretreatment on the efficiency of methane production from semi-dry anaerobic digestion of rose (Rosa rugosa) stalk were investigated at various NaOH loadings (0, 1, 2, and 4% (w/w)). Methane production, process stability and energy balance were analyzed. Results showed that solid-state NaOH pretreatment significantly improved biogas and methane yields of 30-day anaerobic digestion, with increases from 143.7 mL/g volatile solids (VS) added to 157.1 mL/g VS -192.1 mL/g VS added and from 81.8 mL/g VS added to 88.8 mL/g VS-117.7 mL/g VS added, respectively. Solid-state NaOH pretreatment resulted in anaerobic digestion with higher VS reduction and lower technical digestion time. The 4% NaOH-treated group had the highest methane yield of 117.7 mL/g VS added, which was 144% higher compared to the no NaOH-treated group, and the highest net energy recovery. Higher rate of lignocellulose breakage and higher process stability of anaerobic digestion facilitated methane production in the NaOH-pretreated groups.

  18. Evaluation of startup and operation of four anaerobic processes treating a synthetic meat waste

    SciTech Connect

    Stephenson, T.; Lester, J.N.

    1986-03-01

    Two continuous stirred tanks reactors (CSTR) and four anaerobic fluidized bed reactors (AFBR) were used to study the treatment of a synthetic meat waste during single and two-stage anaerobic treatment. Four configurations were investigated; a single-stage CSTR and AFBR and the two-stage systems CSTR-AFBR and AFBR-AFBR. Startup of the anaerobic reactors was achieved within 50 days by use of a regime that included stepped increases in influent COD, methanol substitution of the substrate, and addition of essential trace metals such as cobalt and nickel. Two-stage reactors removed up to 85% of influent COD concentrations of 5000 mg/l, whereas the single-stage AFBR and CSTR removed 76 and 9%, respectively. The proportion of methane in the effluent gases increased as the influent COD concentration was increased. Volumetric production of methane was greatest for the first stage of the AFBR-AFBR system. Solids retention times calculated for the AFBRs ranged from 7 to 12 days, sufficient to support methanogenesis. The AFBRs and two-stage systems were more resistant to an influent pH shock from the operating value of pH 6.8 down to pH 3 than the CSTRs and single-stage reactors. It was concluded that high-rate anaerobic treatment systems were applicable to meat industry wastewaters and that two-stage digestion produced a better quality effluent. 3 references.

  19. The effects of different mixing intensities during anaerobic digestion of the organic fraction of municipal solid waste.

    PubMed

    Lindmark, Johan; Eriksson, Per; Thorin, Eva

    2014-08-01

    Mixing inside an anaerobic digester is often continuous and is not actively controlled. The selected mixing regime can however affect both gas production and the energy efficiency of the biogas plant. This study aims to evaluate these effects and compare three different mixing regimes, 150 RPM and 25 RPM continuous mixing and minimally intermittent mixing for both digestion of fresh substrate and post-digestion of the organic fraction of municipal solid waste. The results show that a lower mixing intensity leads to a higher biogas production rate and higher total biogas production in both cases. 25 RPM continuous mixing and minimally intermittent mixing resulted in similar biogas production after process stabilization, while 150 RPM continuous mixing resulted in lower production throughout the experiment. The lower gas production at 150 RPM could not be explained by the inhibition of volatile fatty acids. Cumulative biogas production until day 31 was 295 ± 2.9, 317 ± 1.9 and 304 ± 2.8N ml/g VS added during digestion of fresh feed and 113 ± 1.3, 134 ± 1.1 and 130 ± 2.3N ml/g VS added during post digestion for the 150 RPM, 25 RPM and minimally mixed intensities respectively. As well as increasing gas production, optimal mixing can improve the energy efficiency of the anaerobic digestion process.

  20. The effects of different mixing intensities during anaerobic digestion of the organic fraction of municipal solid waste.

    PubMed

    Lindmark, Johan; Eriksson, Per; Thorin, Eva

    2014-08-01

    Mixing inside an anaerobic digester is often continuous and is not actively controlled. The selected mixing regime can however affect both gas production and the energy efficiency of the biogas plant. This study aims to evaluate these effects and compare three different mixing regimes, 150 RPM and 25 RPM continuous mixing and minimally intermittent mixing for both digestion of fresh substrate and post-digestion of the organic fraction of municipal solid waste. The results show that a lower mixing intensity leads to a higher biogas production rate and higher total biogas production in both cases. 25 RPM continuous mixing and minimally intermittent mixing resulted in similar biogas production after process stabilization, while 150 RPM continuous mixing resulted in lower production throughout the experiment. The lower gas production at 150 RPM could not be explained by the inhibition of volatile fatty acids. Cumulative biogas production until day 31 was 295 ± 2.9, 317 ± 1.9 and 304 ± 2.8N ml/g VS added during digestion of fresh feed and 113 ± 1.3, 134 ± 1.1 and 130 ± 2.3N ml/g VS added during post digestion for the 150 RPM, 25 RPM and minimally mixed intensities respectively. As well as increasing gas production, optimal mixing can improve the energy efficiency of the anaerobic digestion process. PMID:24814768

  1. Production of citric acid using its extraction wastewater treated by anaerobic digestion and ion exchange in an integrated citric acid-methane fermentation process.

    PubMed

    Xu, Jian; Chen, Yang-Qiu; Zhang, Hong-Jian; Tang, Lei; Wang, Ke; Zhang, Jian-Hua; Chen, Xu-Sheng; Mao, Zhong-Gui

    2014-08-01

    In order to solve the problem of extraction wastewater pollution in citric acid industry, an integrated citric acid-methane fermentation process is proposed in this study. Extraction wastewater was treated by mesophilic anaerobic digestion and then used to make mash for the next batch of citric acid fermentation. The recycling process was done for seven batches. Citric acid production (82.4 g/L on average) decreased by 34.1 % in the recycling batches (2nd-7th) compared with the first batch. And the residual reducing sugar exceeded 40 g/L on average in the recycling batches. Pigment substances, acetic acid, ammonium, and metal ions in anaerobic digestion effluent (ADE) were considered to be the inhibitors, and their effects on the fermentation were studied. Results indicated that ammonium, Na(+) and K(+) in the ADE significantly inhibited citric acid fermentation. Therefore, the ADE was treated by acidic cation exchange resin prior to reuse to make mash for citric acid fermentation. The recycling process was performed for ten batches, and citric acid productions in the recycling batches were 126.6 g/L on average, increasing by 1.7 % compared with the first batch. This process could eliminate extraction wastewater discharge and reduce water resource consumption.

  2. ANAEROBIC DIGESTION OF ANIMAL WASTE: EFFECT OF MODE OF MIXING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Laboratory-scale digesters were operated to study the effect of mixing (via biogas recirculation, impeller mixing, and slurry recirculation) on biogas production. Three sets of experiments were performed using cow manure slurry feed with either 50, 100, or 150 g/L total solids (TS) concentrations (r...

  3. 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. PMID:26101200

  4. Enhanced anaerobic treatment of CSTR-digested effluent from chicken manure: The effect of ammonia inhibition.

    PubMed

    Liu, Zhan-Guang; Zhou, Xue-Fei; Zhang, Ya-Lei; Zhu, Hong-Guang

    2012-01-01

    The effect of ammonia inhibition was evaluated during the enhanced anaerobic treatment of digested effluent from a 700m(3) chicken-manure continuous stirred tank reactor (CSTR). A 12.3L internal circulation (IC) reactor inoculated with an anaerobic granular sludge and operated at 35±1°C was employed for the investigation. With a corresponding organic loading rate of 1.5-3.5kg-COD/m(3)d over a hydraulic retention time of 1.5d, a maximum volumetric biogas production rate of 1.2m(3)/m(3)d and TCOD (total COD) removal efficiency ranging from 70% to 80% was achieved. However, the continual increase in the influent TAN content led to ammonia inhibition in the methanogenesis system. The SCOD/TAN (soluble COD/total ammonia nitrogen) ratio was presented to be the key controlling factor for the anaerobic treatment of semi-digested chicken manure, and further validation through shock loading and ammonia inhibition experiments was conducted. The threshold value of the SCOD/TAN ratio was determined to be 2.4 (corresponding to a TAN of 1250mg/L) at an influent pH of 8.5-9.

  5. 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.

  6. Enhanced anaerobic treatment of CSTR-digested effluent from chicken manure: The effect of ammonia inhibition

    SciTech Connect

    Liu Zhanguang; Zhou Xuefei; Zhang Yalei; Zhu Hongguang

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Enhanced anaerobic treatment of CSTR-digested effluent from chicken manure. Black-Right-Pointing-Pointer The SCOD/TAN (soluble COD/total ammonia nitrogen) ratio was key controlling factor. Black-Right-Pointing-Pointer The threshold of the SCOD/TAN ratio was 2.4 at an influent pH of 8.5-9. - Abstract: The effect of ammonia inhibition was evaluated during the enhanced anaerobic treatment of digested effluent from a 700 m{sup 3} chicken-manure continuous stirred tank reactor (CSTR). A 12.3 L internal circulation (IC) reactor inoculated with an anaerobic granular sludge and operated at 35 {+-} 1 Degree-Sign C was employed for the investigation. With a corresponding organic loading rate of 1.5-3.5 kg-COD/m{sup 3} d over a hydraulic retention time of 1.5 d, a maximum volumetric biogas production rate of 1.2 m{sup 3}/m{sup 3} d and TCOD (total COD) removal efficiency ranging from 70% to 80% was achieved. However, the continual increase in the influent TAN content led to ammonia inhibition in the methanogenesis system. The SCOD/TAN (soluble COD/total ammonia nitrogen) ratio was presented to be the key controlling factor for the anaerobic treatment of semi-digested chicken manure, and further validation through shock loading and ammonia inhibition experiments was conducted. The threshold value of the SCOD/TAN ratio was determined to be 2.4 (corresponding to a TAN of 1250 mg/L) at an influent pH of 8.5-9.

  7. Effect of aerobic and anaerobic exercises on glycemic control in type 1 diabetic youths

    PubMed Central

    Lukács, Andrea; Barkai, László

    2015-01-01

    AIM: To evaluate the long-term effect of aerobic and/or anaerobic exercise on glycemic control in youths with type 1 diabetes. METHODS: Literature review was performed in spring and summer 2014 using PubMed/MEDLINE, Google Scholar, Scopus, and ScienceDirect with the following terms: aerobic, anaerobic, high-intensity, resistance, exercise/training, combined with glycemic/metabolic control, glycated haemoglobin A1c (HbA1c) and type 1 diabetes. Only peer-reviewed articles in English were included published in the last 15 years. It was selected from 1999 to 2014. Glycemic control was measured with HbA1c. Studies with an intervention lasting at least 12 wk were included if the HbA1c was measured before and after the intervention. RESULTS: A total of nine articles were found, and they were published between the years of 2002-2011. The sample size was 401 diabetic youths (166 males and 235 females) with an age range of 10-19 years except one study, in which the age range was 13-30 years. Study participants were from Australia, Tunisia, Lithuania, Taiwan, Turkey, Brazilia, Belgium, Egypt and France. Four studies were aerobic-based, four were combined aerobic and anaerobic programs, and one compared aerobic exercise to anaerobic one. Available studies had insufficient evidence that any type of exercise or combined training would clearly improve the glycemic control in type 1 diabetic youth. Only three (two aerobic-based and one combined) studies could provide a significant positive change in glycemic control. CONCLUSION: The regular physical exercise has several other valuable physiological and health benefits that justify the inclusion of exercise in pediatric diabetes treatment and care. PMID:25897363

  8. Microbial Internal Storage Alters the Carbon Transformation in Dynamic Anaerobic Fermentation.

    PubMed

    Ni, Bing-Jie; Batstone, Damien; Zhao, Bai-Hang; Yu, Han-Qing

    2015-08-01

    Microbial internal storage processes have been demonstrated to occur and play an important role in activated sludge systems under both aerobic and anoxic conditions when operating under dynamic conditions. High-rate anaerobic reactors are often operated at a high volumetric organic loading and a relatively dynamic profile, with large amounts of fermentable substrates. These dynamic operating conditions and high catabolic energy availability might also facilitate the formation of internal storage polymers by anaerobic microorganisms. However, so far information about storage under anaerobic conditions (e.g., anaerobic fermentation) as well as its consideration in anaerobic process modeling (e.g., IWA Anaerobic Digestion Model No. 1, ADM1) is still sparse. In this work, the accumulation of storage polymers during anaerobic fermentation was evaluated by batch experiments using anaerobic methanogenic sludge and based on mass balance analysis of carbon transformation. A new mathematical model was developed to describe microbial storage in anaerobic systems. The model was calibrated and validated by using independent data sets from two different anaerobic systems, with significant storage observed, and effectively simulated in both systems. The inclusion of the new anaerobic storage processes in the developed model allows for more successful simulation of transients due to lower accumulation of volatile fatty acids (correction for the overestimation of volatile fatty acids), which mitigates pH fluctuations. Current models such as the ADM1 cannot effectively simulate these dynamics due to a lack of anaerobic storage mechanisms.

  9. Evaluation of hydrogen and methane production from sugarcane bagasse hemicellulose hydrolysates by two-stage anaerobic digestion process.

    PubMed

    Baêta, Bruno Eduardo Lobo; Lima, Diego Roberto Sousa; Filho, José Gabriel Balena; Adarme, Oscar Fernando Herrera; Gurgel, Leandro Vinícius Alves; Aquino, Sérgio Francisco de

    2016-10-01

    This study aimed at optimizing the net energy recovery from hydrogen and methane production through anaerobic digestion of the hemicellulose hydrolysate (HH) obtained by desirable conditions (DC) of autohydrolysis pretreatment (AH) of sugarcane bagasse (SB). Anaerobic digestion was carried out in a two-stage (acidogenic-methanogenic) batch system where the acidogenic phase worked as a hydrolysis and biodetoxification step. This allowed the utilization of more severe AH pretreatment conditions, i.e. T=178.6°C and t=55min (DC3) and T=182.9°C and t=40.71min (DC4). Such severe conditions resulted in higher extraction of hemicelluloses from SB (DC1=68.07%, DC2=48.99%, DC3=77.40% and DC4=73.90%), which consequently improved the net energy balance of the proposed process. The estimated energy from the combustion of both biogases (H2 and CH4) accumulated during the two-stage anaerobic digestion of HH generated by DC4 condition was capable of producing a net energy of 3.15MJ·kgSB(-1)dry weight.

  10. Evaluation of hydrogen and methane production from sugarcane bagasse hemicellulose hydrolysates by two-stage anaerobic digestion process.

    PubMed

    Baêta, Bruno Eduardo Lobo; Lima, Diego Roberto Sousa; Filho, José Gabriel Balena; Adarme, Oscar Fernando Herrera; Gurgel, Leandro Vinícius Alves; Aquino, Sérgio Francisco de

    2016-10-01

    This study aimed at optimizing the net energy recovery from hydrogen and methane production through anaerobic digestion of the hemicellulose hydrolysate (HH) obtained by desirable conditions (DC) of autohydrolysis pretreatment (AH) of sugarcane bagasse (SB). Anaerobic digestion was carried out in a two-stage (acidogenic-methanogenic) batch system where the acidogenic phase worked as a hydrolysis and biodetoxification step. This allowed the utilization of more severe AH pretreatment conditions, i.e. T=178.6°C and t=55min (DC3) and T=182.9°C and t=40.71min (DC4). Such severe conditions resulted in higher extraction of hemicelluloses from SB (DC1=68.07%, DC2=48.99%, DC3=77.40% and DC4=73.90%), which consequently improved the net energy balance of the proposed process. The estimated energy from the combustion of both biogases (H2 and CH4) accumulated during the two-stage anaerobic digestion of HH generated by DC4 condition was capable of producing a net energy of 3.15MJ·kgSB(-1)dry weight. PMID:27393834

  11. Anaerobic thermophilic culture

    DOEpatents

    Ljungdahl, Lars G.; Wiegel, Jurgen K. W.

    1981-01-01

    A newly discovered thermophilic anaerobe is described that was isolated in a biologically pure culture and designated Thermoanaerobacter ethanolicus ATCC 3/550. T. Ethanolicus is cultured in aqueous nutrient medium under anaerobic, thermophilic conditions and is used in a novel process for producing ethanol by subjecting carbohydrates, particularly the saccharides, to fermentation action of the new microorganism in a biologically pure culture.

  12. Reuse of recalcitrant-rich anaerobic effluent as dilution water after enhancement of biodegradability by Fenton processes.

    PubMed

    Arimi, Milton M; Zhang, Yongjun; Namango, Saul S; Geißen, Sven-Uwe

    2016-03-01

    Anaerobic digestion is used to treat effluents with a lot of organics, such as molasses distillery wastewater (MDW) which is the effluent of bioethanol production from molasses. The raw MDW requires a lot of dilution water before biodigestion, while the digested MDW has high level of recalcitrants which are problematic for its discharge. This study investigated ferric coagulation, Fenton, Fenton-like (with ferric ions as catalyst) processes and their combinations on the biodegradability of digested MDW. The Fenton and Fenton-like processes after coagulation increased the MDW biodegradability defined by (BOD5/COD) from 0.07 to (0.4-0.6) and saved 50% of H2O2 consumed in the classic Fenton process. The effluent from coagulation coupled to a Fenton-like process was used as dilution water for the raw MDW before the anaerobic digestion. The process was stable with volumetric loading of approx. 2.7 g COD/L/d. It resulted in increased overall biogas recovery and significantly decreased the demand for the dilution water. PMID:26692412

  13. Super blue box recycling (SUBBOR) enhanced two-stage anaerobic digestion process for recycling municipal solid waste: laboratory pilot studies.

    PubMed

    Vogt, G M; Liu, H W; Kennedy, K J; Vogt, H S; Holbein, B E

    2002-12-01

    The super blue box recycling (SUBBOR) process is an enhanced, multi-stage anaerobic digestion process for mixed municipal solid waste (MSW) and other biomass feedstock materials. The technology centers on enhanced high solids, thermophilic digestion after steam-pressure disruption of the ligno-cellulosic fiber components that are recalcitrant to conventional anaerobic digestion. Mixed MSW, rich in organic components but also containing inorganic materials, such as glass, aluminum and steel, as well as non-digestible plastic materials, has been laboratory pilot tested with a fully integrated process train designed to treat and recycle all of the MSW components. Methane yields from the MSW were 0.36 m3 CH4/kg volatile solids (VS) representing a 40% increase over the yield obtained from conventional single stage digestion. The secondary digestion step after steam pressure disruption also provided a 40% improvement in total solids and VS reduction. The residual organic fraction following two-stage digestion was fine in texture and was recovered as a clean peat fraction with reduced contents of heavy metal and other fugitive non-digested contaminants. Mass and energy balance determinations indicated a high degree of MSW diversion from landfill disposal (>80%) was achievable by the SUBBOR process as well as substantial net electrical and thermal energy production. Continuous long-term trials of the SUBBOR process at 25,000 tonnes/year are underway.

  14. Improved anaerobic digestion of a thermally pretreated mixture of physicochemical sludge; broiler excreta and sugar cane wastes (SCW): Effect on organic matter solubilization, biodegradability and bioenergy production.

    PubMed

    Nava-Valente, Noemí; Alvarado-Lassman, Alejandro; Nativitas-Sandoval, Liliana S; Mendez-Contreras, Juan M

    2016-01-01

    Thermal pretreatment effect of a mixture of organic wastes (physicochemical sludge, excreta of broiler chickens and sugarcane wastes (SCW)) in the solubilization and biodegradability organic matter as well as bioenergy production by anaerobic digestion was evaluated. Two different mixtures of physicochemical sludge, excreta of broiler chickens and SCW (70%, 15%, 15% and 60%, 20%, 20% of VS, respectively) were treated at different temperatures (80 °C, 85 °C and 90 °C) and contact time (30, 60 and 90 min). Results indicate that, organic matter solubilization degree increased from 1.14 to 6.56%; subsequently, in the anaerobic digestion process, an increase of 50% in the volatile solids removal and 10% in biogas production was observed, while, retention time decreased from 23 up to 9 days. The results obtained were similar to pilot-scale. In both experimental scales it showed that the synergy produced by the simultaneous anaerobic digestion of different substrates could increase bioenergy production up to 1.3 L bio g(-1) VS removed and 0.82 L CH4 g(-1) VS removed. The treatment conditions presented in this study allow for large residue quantities to be treated and large bioenergy quantities to be produced (10% higher than during conventional treatment) without increasing the anaerobic digester volume.

  15. Improved anaerobic digestion of a thermally pretreated mixture of physicochemical sludge; broiler excreta and sugar cane wastes (SCW): Effect on organic matter solubilization, biodegradability and bioenergy production.

    PubMed

    Nava-Valente, Noemí; Alvarado-Lassman, Alejandro; Nativitas-Sandoval, Liliana S; Mendez-Contreras, Juan M

    2016-01-01

    Thermal pretreatment effect of a mixture of organic wastes (physicochemical sludge, excreta of broiler chickens and sugarcane wastes (SCW)) in the solubilization and biodegradability organic matter as well as bioenergy production by anaerobic digestion was evaluated. Two different mixtures of physicochemical sludge, excreta of broiler chickens and SCW (70%, 15%, 15% and 60%, 20%, 20% of VS, respectively) were treated at different temperatures (80 °C, 85 °C and 90 °C) and contact time (30, 60 and 90 min). Results indicate that, organic matter solubilization degree increased from 1.14 to 6.56%; subsequently, in the anaerobic digestion process, an increase of 50% in the volatile solids removal and 10% in biogas production was observed, while, retention time decreased from 23 up to 9 days. The results obtained were similar to pilot-scale. In both experimental scales it showed that the synergy produced by the simultaneous anaerobic digestion of different substrates could increase bioenergy production up to 1.3 L bio g(-1) VS removed and 0.82 L CH4 g(-1) VS removed. The treatment conditions presented in this study allow for large residue quantities to be treated and large bioenergy quantities to be produced (10% higher than during conventional treatment) without increasing the anaerobic digester volume. PMID:26819145

  16. Effect of ammoniacal nitrogen on one-stage and two-stage anaerobic digestion of food waste.

    PubMed

    Ariunbaatar, Javkhlan; Scotto Di Perta, Ester; Panico, Antonio; Frunzo, Luigi; Esposito, Giovanni; Lens, Piet N L; Pirozzi, Francesco

    2015-04-01

    This research compares the operation of one-stage and two-stage anaerobic continuously stirred tank reactor (CSTR) systems fed semi-continuously with food waste. The main purpose was to investigate the effects of ammoniacal nitrogen on the anaerobic digestion process. The two-stage system gave more reliable operation compared to one-stage due to: (i) a better pH self-adjusting capacity; (ii) a higher resistance to organic loading shocks; and (iii) a higher conversion rate of organic substrate to biomethane. Also a small amount of biohydrogen was detected from the first stage of the two-stage reactor making this system attractive for biohythane production. As the digestate contains ammoniacal nitrogen, re-circulating it provided the necessary alkalinity in the systems, thus preventing an eventual failure by volatile fatty acids (VFA) accumulation. However, re-circulation also resulted in an ammonium accumulation, yielding a lower biomethane production. Based on the batch experimental results the 50% inhibitory concentration of total ammoniacal nitrogen on the methanogenic activities was calculated as 3.8 g/L, corresponding to 146 mg/L free ammonia for the inoculum used for this research. The two-stage system was affected by the inhibition more than the one-stage system, as it requires less alkalinity and the physically separated methanogens are more sensitive to inhibitory factors, such as ammonium and propionic acid.

  17. Effect of ammoniacal nitrogen on one-stage and two-stage anaerobic digestion of food waste.

    PubMed

    Ariunbaatar, Javkhlan; Scotto Di Perta, Ester; Panico, Antonio; Frunzo, Luigi; Esposito, Giovanni; Lens, Piet N L; Pirozzi, Francesco

    2015-04-01

    This research compares the operation of one-stage and two-stage anaerobic continuously stirred tank reactor (CSTR) systems fed semi-continuously with food waste. The main purpose was to investigate the effects of ammoniacal nitrogen on the anaerobic digestion process. The two-stage system gave more reliable operation compared to one-stage due to: (i) a better pH self-adjusting capacity; (ii) a higher resistance to organic loading shocks; and (iii) a higher conversion rate of organic substrate to biomethane. Also a small amount of biohydrogen was detected from the first stage of the two-stage reactor making this system attractive for biohythane production. As the digestate contains ammoniacal nitrogen, re-circulating it provided the necessary alkalinity in the systems, thus preventing an eventual failure by volatile fatty acids (VFA) accumulation. However, re-circulation also resulted in an ammonium accumulation, yielding a lower biomethane production. Based on the batch experimental results the 50% inhibitory concentration of total ammoniacal nitrogen on the methanogenic activities was calculated as 3.8 g/L, corresponding to 146 mg/L free ammonia for the inoculum used for this research. The two-stage system was affected by the inhibition more than the one-stage system, as it requires less alkalinity and the physically separated methanogens are more sensitive to inhibitory factors, such as ammonium and propionic acid. PMID:25613216

  18. Anaerobic bacteria

    MedlinePlus

    Anaerobic bacteria are bacteria that do not live or grow when oxygen is present. In humans, these ... Goldstein EJ. Diseases caused by non-spore forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman's ...

  19. Modeling multi-component transport and enhanced anaerobic dechlorination processes in a single fracture-clay matrix system.

    PubMed

    Chambon, Julie C; Broholm, Mette M; Binning, Philip J; Bjerg, Poul L

    2010-03-01

    Clayey tills contaminated with chlorinated solvents are a threat to groundwater and are difficult to remediate. A numerical model is developed for assessing leaching processes and for simulating the remediation via enhanced anaerobic dechlorination. The model simulates the transport of a contaminant in a single fracture-clay matrix system coupled with a reactive model for anaerobic dechlorination. The model takes into account microbially driven anaerobic dechlorination, where sequential Monod kinetics with competitive inhibition is used to model the reaction rates, and degradation is localized to account for potential pore size limitations on microbial entry to the clay matrix. The model is used to assess the distribution of TCE and its daughter products in the clay matrix and the concentration of the different compounds at the outlet of the fracture. The time frame for complete cleanup and the contaminant flux out of the clay system are assessed for different distributions of microbial degradation. Results from a set of scenarios show that time to remove 90% of the initial mass is halved when dechlorination occurs in a 5cm reaction zone in the clay at the fracture-matrix interface (from 419 to 195years) and decreases by an order of magnitude when dechlorination occurs in the entire matrix (to 32years). The fracture spacing and the microbial parameters are shown to be the critical parameter for estimation of time frames depending on the system in question. Generally, the system is more sensitive to the physical processes, mainly diffusion in the matrix, than to the biogeochemical processes, when dechlorination is assumed to take place in a limited reaction zone only. The inclusion of sequential dechlorination in clay fracture transport models is crucial, as the contaminant flux to the aquifer will increase as a result of degradation due to the higher mobility of the formed daughter products DCE and VC. The model is used to examine the relationship between flux

  20. Effect of gender on the GH-IGF-I response to anaerobic exercise in young adults.

    PubMed

    Eliakim, Alon; Nemet, Dan; Most, Guy; Rakover, Noa; Pantanowitz, Michal; Meckel, Yoav

    2014-12-01

    Exercise-associated effects on the growth hormone-insulin-like growth factor-I (GH-IGF-I) axis were studied, mainly after aerobic exercise. We determined the gender effect on the GH-IGF-I axis response to a standard all-out Wingate anaerobic test (WAnT) in healthy active young adult men and women (men = 12 and women = 16; age range: 24-34 years). Blood samples for GH and IGF-I, key elements of the GH-IGF-I axis, were collected before and 20, 30, 40, and 60 minutes after the beginning of exercise. In addition, we collected postexercise blood lactate levels. Postexercise lactate levels were higher among men; however, this difference did not reach statistical significance (13.8 ± 1.3 vs. 11.1 ± 1.0 mmol·L, respectively; p = 0.1). The WAnT was associated with a significant increase in GH in both genders. However, GH peak was greater among women (10.8 ± 1.8 vs. 5.6 ± 1.4 ng·ml, in women and men, respectively; p < 0.01). In addition, postexercise GH peak occurred significantly earlier in female (20 minutes) compared with male participants (40 minutes). Exercise was associated with a significant increase in IGF only among men (from 166.8 ± 8.4 to 186.9 ± 9.3; p < 0.02); however, no significant between-gender effect was found. In summary, supramaximal anaerobic exercise was associated with a greater and earlier postexercise GH peak in women compared with men. All together, the results suggest anaerobic exercise-related anabolic-type hormonal response.

  1. Evaluation of methane generation and process stability from anaerobic co-digestion of sugar beet by-product and cow manure.

    PubMed

    Aboudi, Kaoutar; Álvarez-Gallego, Carlos José; Romero-García, Luis Isidoro

    2016-05-01

    The effect of mesophilic anaerobic co-digestion of dried pellets of exhausted sugar beet cossettes (ESBC-DP) and cow manure (CM) on the enhancement of methane generation and process stability were studied with the aim to select the best substrate mixture ratio. A series of batch experiments was conducted using the following five mixture ratios of ESBC-DP:CM: 0:100; 25:75; 50:50; 75:25 and 100:0. Best results were obtained from mixture ratios with ESBC-DP proportions in the range of 25-50%. Mixture ratio of 50:50 showed a specific methane production (SMP) increase of 81.4% and 25.5%, respectively, in comparison with mono-digestion of ESBC-DP and CM. Evolution of the indirect parameter named acidogenic substrate as carbon (ASC) could be used to provide more insight about the process stability of anaerobic digestion. ASC accumulation was observed in reactors with higher ESBC-DP proportions leading to a delay in VFAs consumption and conversion into methane.

  2. Effects of lipids on thermophilic anaerobic digestion and reduction of lipid inhibition upon addition of bentonite.

    PubMed

    Angelidaki, I; Petersen, S P; Ahring, B K

    1990-07-01

    The effect of bentonite-bound oil on thermophilic anaerobic digestion of cattle manure was investigated. In digestor experiments, addition of oil was found to be inhibitory during start-up and the inhibitory effect was less pronounced when the oil was added in the form of bentonite-bound oil compared to when the oil was added alone. After adaptation of the digestors, very rapid degradation of oil was observed and more than 80% of the oil was degraded within a few hours after daily feeding. In batch experiments, glyceride trioleate was found to be inhibitory to thermophilic anaerobic digestion when the concentrations were higher than 2.0 g/l. However, addition of bentonite (a clay mineral) at concentrations of 0.15% and 0.45% was found to partly overcome this inhibition. Addition of calcium chloride in concentration of 3 mM (0.033% w/v) showed a similar positive effect on the utilization of oil, but the effect was lower than with bentonite. PMID:1366749

  3. Role of oxidants in enhancing dewaterability of anaerobically digested sludge through Fe (II) activated oxidation processes: hydrogen peroxide versus persulfate

    PubMed Central

    Song, Kang; Zhou, Xu; Liu, Yiqi; Gong, Yanyan; Zhou, Beibei; Wang, Dongbo; Wang, Qilin

    2016-01-01

    Improving dewaterability of sludge is important for the disposal of sludge in wastewater treatment plants (WWTPs). This study, for the first time, investigated the Fe(II) activated oxidization processes in improving anaerobically digested sludge (ADS) dewaterability. The combination of Fe(II) (0–100 mg/g total solids (TS)) and persulfate (0–1,000 mg/g TS) under neutral pH as well as the combination of Fe(II) (0–100 mg/g TS) and hydrogen peroxide (HP) (0–1,000 mg/g TS) under pH 3.0 were used to examine and compare their effect on the ADS dewaterability enhancement. The highest ADS dewaterability enhancement was attained at 25 mg Fe(II)/g TS and 50 mg HP/g TS, when the CST (CST: the capillary suction time, a sludge dewaterability indicator) was reduced by 95%. In contrast, the highest CST reduction in Fe(II)-persulfate conditioning was 90%, which was obtained at 50 mg Fe(II)/g TS and 250 mg persulfate/g TS. The results showed that Fe(II)-HP conditioning was comparable with Fe(II)-persulfate conditioning in terms of highest CST reduction. Economic analysis suggested that the Fe(II)-HP conditioning was more promising for improving ADS dewaterability compared with Fe(II)-persulfate conditioning, with the saving being up to $65,000 per year in a WWTP with a population equivalent of 100,000. PMID:27109500

  4. High-Rate Anaerobic Side-Stream Reactor (ASSR) Processes to Minimize the Production of Excess Sludge.

    PubMed

    Park, Chul; Chon, Dong-Hyun

    2015-12-01

    High-rate anaerobic side-stream reactor (ASSR) processes were developed to minimize excess sludge production during wastewater treatment. New ASSRs were operated in 2.5-day solids retention time (SRT), much shorter than 10-day SRT used by the commercial sludge reduction process. The 2.5-day was selected based on literature review and preliminary studies, showing that maximum solublization of key floc components, such as divalent cations, extracellular polymeric substances (EPS), and protease, occur within 2 to 3 days of anaerobic digestion. The laboratory reactor study showed that 2.5-day ASSR systems produced approximately 60 and 20% less sludge than the control (no ASSR) and the 10-day ASSR, respectively. The experimental systems showed acceptable effluent quality, despite minimal sludge wastage. This was possible because sludge EPS were continuously released/degraded and regenerated as sludge underwent recirculation between ASSR and the aerobic basin. The results supported that the activated sludge process incorporating small ASSRs significantly decrease the production of excess sludge during wastewater treatment.

  5. Increasing biogas production from sewage sludge anaerobic co-digestion process by adding crude glycerol from biodiesel industry.

    PubMed

    Nartker, Steven; Ammerman, Michelle; Aurandt, Jennifer; Stogsdil, Michael; Hayden, Olivia; Antle, Chad

    2014-12-01

    In an effort to convert waste streams to energy in a green process, glycerol from biodiesel manufacturing has been used to increase the gas production and methane content of biogas within a mesophilic anaerobic co-digestion process using primary sewage sludge. Glycerol was systematically added to the primary digester from 0% to 60% of the organic loading rate (OLR). The optimum glycerol loading range was from 25% to 60% OLR. This resulted in an 82-280% improvement in specific gas production. Following the feeding schedule described, the digesters remained balanced and healthy until inhibition was achieved at 70% glycerol OLR. This suggests that high glycerol loadings are possible if slow additions are upheld in order to allow the bacterial community to adjust properly. Waste water treatment plant operators with anaerobic digesters can use the data to increase loadings and boost biogas production to enhance energy conversion. This process provides a safe, environmentally friendly method to convert a typical waste stream to an energy stream of biogas.

  6. Increasing biogas production from sewage sludge anaerobic co-digestion process by adding crude glycerol from biodiesel industry.

    PubMed

    Nartker, Steven; Ammerman, Michelle; Aurandt, Jennifer; Stogsdil, Michael; Hayden, Olivia; Antle, Chad

    2014-12-01

    In an effort to convert waste streams to energy in a green process, glycerol from biodiesel manufacturing has been used to increase the gas production and methane content of biogas within a mesophilic anaerobic co-digestion process using primary sewage sludge. Glycerol was systematically added to the primary digester from 0% to 60% of the organic loading rate (OLR). The optimum glycerol loading range was from 25% to 60% OLR. This resulted in an 82-280% improvement in specific gas production. Following the feeding schedule described, the digesters remained balanced and healthy until inhibition was achieved at 70% glycerol OLR. This suggests that high glycerol loadings are possible if slow additions are upheld in order to allow the bacterial community to adjust properly. Waste water treatment plant operators with anaerobic digesters can use the data to increase loadings and boost biogas production to enhance energy conversion. This process provides a safe, environmentally friendly method to convert a typical waste stream to an energy stream of biogas. PMID:25249492

  7. A hybrid cascade control scheme for the VFA and COD regulation in two-stage anaerobic digestion processes.

    PubMed

    Méndez-Acosta, H O; Campos-Rodríguez, A; González-Álvarez, V; García-Sandoval, J P; Snell-Castro, R; Latrille, E

    2016-10-01

    A hybrid (continuous-discrete) cascade control is proposed to regulate both, volatile fatty acids (VFA) and chemical oxygen demand (COD) concentrations in two-stage (acidogenic-methanogenic) anaerobic digestion (TSAD) processes. The outer loop is a discrete controller that regulates the COD concentration of the methanogenic bioreactor by using a daily off-line measurement and that modifies the set-point tracked by inner loop, which manipulates the dilution rate to regulate the VFA concentration of the acidogenic bioreactor, estimated by continuous on-line conductivity measurements, avoiding acidification. The experimental validation was conducted in a TSAD process for the treatment of tequila vinasses during 110days. Results showed that the proposed cascade control scheme was able to achieve the VFA and COD regulation by using conventional measurements under different set-point values in spite of adverse common scenarios in full-scale anaerobic digestion processes. Microbial composition analysis showed that the controller also favors the abundance and diversity toward methane production.

  8. A hybrid cascade control scheme for the VFA and COD regulation in two-stage anaerobic digestion processes.

    PubMed

    Méndez-Acosta, H O; Campos-Rodríguez, A; González-Álvarez, V; García-Sandoval, J P; Snell-Castro, R; Latrille, E

    2016-10-01

    A hybrid (continuous-discrete) cascade control is proposed to regulate both, volatile fatty acids (VFA) and chemical oxygen demand (COD) concentrations in two-stage (acidogenic-methanogenic) anaerobic digestion (TSAD) processes. The outer loop is a discrete controller that regulates the COD concentration of the methanogenic bioreactor by using a daily off-line measurement and that modifies the set-point tracked by inner loop, which manipulates the dilution rate to regulate the VFA concentration of the acidogenic bioreactor, estimated by continuous on-line conductivity measurements, avoiding acidification. The experimental validation was conducted in a TSAD process for the treatment of tequila vinasses during 110days. Results showed that the proposed cascade control scheme was able to achieve the VFA and COD regulation by using conventional measurements under different set-point values in spite of adverse common scenarios in full-scale anaerobic digestion processes. Microbial composition analysis showed that the controller also favors the abundance and diversity toward methane production. PMID:27474953

  9. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  11. Effects of dietary Acid load on exercise metabolism and anaerobic exercise performance.

    PubMed

    Caciano, Susan L; Inman, Cynthia L; Gockel-Blessing, Elizabeth E; Weiss, Edward P

    2015-06-01

    Dietary acid load, quantified as the potential renal acid load (PRAL) of the diet, affects systemic pH and acid-base regulation. In a previous cross-sectional study, we reported that a low dietary PRAL (i.e. alkaline promoting diet) is associated with higher respiratory exchange ratio (RER) values during maximal exercise. The purpose of the present study was to confirm the previous findings with a short-term dietary intervention study. Additionally, we sought to determine if changes in PRAL affects submaximal exercise RER (as a reflection of substrate utilization) and anaerobic exercise performance. Subjects underwent a graded treadmill exercise test (GXT) to exhaustion and an anaerobic exercise performance test on two occasions, once after following a low-PRAL diet and on a separate occasion, after a high-PRAL diet. The diets were continued as long as needed to achieve an alkaline or acid fasted morning urine pH, respectively, with all being 4-9 days in duration. RER was measured during the GXT with indirect calorimetry. The anaerobic performance test was a running time-to-exhaustion test lasting 1-4 min. Maximal exercise RER was lower in the low-PRAL trial compared to the high-PRAL trial (1.10 ± 0.02 vs. 1.20 ± 0.05, p = 0.037). The low-PRAL diet also resulted in a 21% greater time to exhaustion during anaerobic exercise (2.56 ± 0.36 vs. 2.11 ± 0.31 sec, p = 0.044) and a strong tendency for lower RER values during submaximal exercise at 70% VO2max (0.88 ± 0.02 vs. 0.96 ± 0.04, p = 0.060). Contrary to our expectations, a short-term low-PRAL (alkaline promoting) diet resulted in lower RER values during maximal-intensity exercise. However, the low-PRAL diet also increased anaerobic exercise time to exhaustion and appears to have shifted submaximal exercise substrate utilization to favor lipid oxidation and spare carbohydrate, both of which would be considered favorable effects in the context of exercise performance. Key pointsShort-term (4-9 days) changes in

  12. Effects of Dietary Acid Load on Exercise Metabolism and Anaerobic Exercise Performance

    PubMed Central

    Caciano, Susan L.; Inman, Cynthia L.; Gockel-Blessing, Elizabeth E.; Weiss, Edward P.

    2015-01-01

    Dietary acid load, quantified as the potential renal acid load (PRAL) of the diet, affects systemic pH and acid-base regulation. In a previous cross-sectional study, we reported that a low dietary PRAL (i.e. alkaline promoting diet) is associated with higher respiratory exchange ratio (RER) values during maximal exercise. The purpose of the present study was to confirm the previous findings with a short-term dietary intervention study. Additionally, we sought to determine if changes in PRAL affects submaximal exercise RER (as a reflection of substrate utilization) and anaerobic exercise performance. Subjects underwent a graded treadmill exercise test (GXT) to exhaustion and an anaerobic exercise performance test on two occasions, once after following a low-PRAL diet and on a separate occasion, after a high-PRAL diet. The diets were continued as long as needed to achieve an alkaline or acid fasted morning urine pH, respectively, with all being 4-9 days in duration. RER was measured during the GXT with indirect calorimetry. The anaerobic performance test was a running time-to-exhaustion test lasting 1-4 min. Maximal exercise RER was lower in the low-PRAL trial compared to the high-PRAL trial (1.10 ± 0.02 vs. 1.20 ± 0.05, p = 0.037). The low-PRAL diet also resulted in a 21% greater time to exhaustion during anaerobic exercise (2.56 ± 0.36 vs. 2.11 ± 0.31 sec, p = 0.044) and a strong tendency for lower RER values during submaximal exercise at 70% VO2max (0.88 ± 0.02 vs. 0.96 ± 0.04, p = 0.060). Contrary to our expectations, a short-term low-PRAL (alkaline promoting) diet resulted in lower RER values during maximal-intensity exercise. However, the low-PRAL diet also increased anaerobic exercise time to exhaustion and appears to have shifted submaximal exercise substrate utilization to favor lipid oxidation and spare carbohydrate, both of which would be considered favorable effects in the context of exercise performance. Key points Short-term (4-9 days) changes in

  13. Modelling phosphorus (P), sulfur (S) and iron (Fe) interactions for dynamic simulations of anaerobic digestion processes.

    PubMed

    Flores-Alsina, Xavier; Solon, Kimberly; Kazadi Mbamba, Christian; Tait, Stephan; Gernaey, Krist V; Jeppsson, Ulf; Batstone, Damien J

    2016-05-15

    This paper proposes a series of extensions to functionally upgrade the IWA Anaerobic Digestion Model No. 1 (ADM1) to allow for plant-wide phosphorus (P) simulation. The close interplay between the P, sulfur (S) and iron (Fe) cycles requires a substantial (and unavoidable) increase in model complexity due to the involved three-phase physico-chemical and biological transformations. The ADM1 version, implemented in the plant-wide context provided by the Benchmark Simulation Model No. 2 (BSM2), is used as the basic platform (A0). Three different model extensions (A1, A2, A3) are implemented, simulated and evaluated. The first extension (A1) considers P transformations by accounting for the kinetic decay of polyphosphates (XPP) and potential uptake of volatile fatty acids (VFA) to produce polyhydroxyalkanoates (XPHA) by phosphorus accumulating organisms (XPAO). Two variant extensions (A2,1/A2,2) describe biological production of sulfides (SIS) by means of sulfate reducing bacteria (XSRB) utilising hydrogen only (autolithotrophically) or hydrogen plus organic acids (heterorganotrophically) as electron sources, respectively. These two approaches also consider a potential hydrogen sulfide ( [Formula: see text] inhibition effect and stripping to the gas phase ( [Formula: see text] ). The third extension (A3) accounts for chemical iron (III) ( [Formula: see text] ) reduction to iron (II) ( [Formula: see text] ) using hydrogen ( [Formula: see text] ) and sulfides (SIS) as electron donors. A set of pre/post interfaces between the Activated Sludge Model No. 2d (ASM2d) and ADM1 are furthermore proposed in order to allow for plant-wide (model-based) analysis and study of the interactions between the water and sludge lines. Simulation (A1 - A3) results show that the ratio between soluble/particulate P compounds strongly depends on the pH and cationic load, which determines the capacity to form (or not) precipitation products. Implementations A1 and A2,1/A2,2 lead to a reduction in

  14. Modelling phosphorus (P), sulfur (S) and iron (Fe) interactions for dynamic simulations of anaerobic digestion processes.

    PubMed

    Flores-Alsina, Xavier; Solon, Kimberly; Kazadi Mbamba, Christian; Tait, Stephan; Gernaey, Krist V; Jeppsson, Ulf; Batstone, Damien J

    2016-05-15

    This paper proposes a series of extensions to functionally upgrade the IWA Anaerobic Digestion Model No. 1 (ADM1) to allow for plant-wide phosphorus (P) simulation. The close interplay between the P, sulfur (S) and iron (Fe) cycles requires a substantial (and unavoidable) increase in model complexity due to the involved three-phase physico-chemical and biological transformations. The ADM1 version, implemented in the plant-wide context provided by the Benchmark Simulation Model No. 2 (BSM2), is used as the basic platform (A0). Three different model extensions (A1, A2, A3) are implemented, simulated and evaluated. The first extension (A1) considers P transformations by accounting for the kinetic decay of polyphosphates (XPP) and potential uptake of volatile fatty acids (VFA) to produce polyhydroxyalkanoates (XPHA) by phosphorus accumulating organisms (XPAO). Two variant extensions (A2,1/A2,2) describe biological production of sulfides (SIS) by means of sulfate reducing bacteria (XSRB) utilising hydrogen only (autolithotrophically) or hydrogen plus organic acids (heterorganotrophically) as electron sources, respectively. These two approaches also consider a potential hydrogen sulfide ( [Formula: see text] inhibition effect and stripping to the gas phase ( [Formula: see text] ). The third extension (A3) accounts for chemical iron (III) ( [Formula: see text] ) reduction to iron (II) ( [Formula: see text] ) using hydrogen ( [Formula: see text] ) and sulfides (SIS) as electron donors. A set of pre/post interfaces between the Activated Sludge Model No. 2d (ASM2d) and ADM1 are furthermore proposed in order to allow for plant-wide (model-based) analysis and study of the interactions between the water and sludge lines. Simulation (A1 - A3) results show that the ratio between soluble/particulate P compounds strongly depends on the pH and cationic load, which determines the capacity to form (or not) precipitation products. Implementations A1 and A2,1/A2,2 lead to a reduction in

  15. Effects of exercise continued until anaerobic threshold on balance performance in male basketball players.

    PubMed

    Erkmen, Nurtekin; Suveren, Sibel; Göktepe, Ahmet Salim

    2012-06-01

    The objective of the present study was to determine the effects of exercise continued until the anaerobic threshold on balance performance in basketball players. Twelve male basketball players (age = 20.92 ± 2.81 years, body height = 192.72 ± 7.61 cm, body mass = 88.09 ± 8.41 kg, training experience = 7.17 ± 3.10 years) volunteered to participate in this study. A Kinesthetic Ability Trainer (KAT 2000 stabilometer) was used to measure the balance performance. Balance tests consisted of static tests on dominant, nondominant and double leg stance. The Bruce Protocol was performed by means of a treadmill. The exercise protocol was terminated when the subject passed the anaerobic threshold. After the exercise protocol, balance measurements were immediately repeated. Statistical differences between pre and post-exercise for dominant, nondominant and double leg stance were determined by the paired samples t-test according to the results of the test of normality. The post-exercise balance score on the dominant leg was significantly higher than pre-exercise (t = -2.758, p < 0.05). No differences existed between pre- and post-exercise in the balance scores of the nondominant leg after the exercise protocol (t = 0.428, p > 0.05). A significant difference was found between pre and post-exercise balance scores in the double leg stance (t = -2.354, p < 0.05). The main finding of this study was that an incremental exercise continued until the anaerobic threshold decreased balance performance on the dominant leg in basketball players, but did not alter it in the nondominant leg.

  16. Anaerobic-fed and sequencing-batch treatment of sugar-beet processing wastes: a comparative study.

    PubMed

    Alkaya, Emrah; Demirer, Göksel N

    2011-03-01

    The aim of this study was to compare a batch-fed continuously mixed anaerobic reactor (FCMR) with an anaerobic sequencing batch reactor (ASBR), in terms of waste stabilization and methane production treating sugar-beet processing wastewater and beet-pulp simultaneously. A reactor was operated as FCMR, which then was operated as an ASBR by changing operational conditions after the steady-state was reached. Although the hydraulic retention time value of the ASBR configuration was lower (8 days) than that of the FCMR (15 days) and the corresponding organic loading rate (OLR) was higher (0.71 to 1.33 g COD/L x d), increased biomass retention enabled a significant increase in biomethanation for the ASBR configuration. So, methane production yield of 255 +/- 11 mL/g COD-added was increased to 337 +/- 15 mL/g COD-added (32.2% increase in methane yield) when the configuration was changed from FCMR to ASBR. The experimental results indicated that the ASBR configuration, which was applied to sugar-beet processing wastes for the first time, was superior to the FCMR configuration.

  17. Effects of Acute Beta-Alanine Supplementation on Anaerobic Performance in Trained Female Cyclists.

    PubMed

    Glenn, Jordan M; Smith, Keyona; Moyen, Nicole E; Binns, Ashley; Gray, Michelle

    2015-01-01

    Longitudinal beta-alanine (BA) supplementation can improve exercise performance in males through increases in carnosine; however, females experience greater relative increases in carnosine compared to males. This potentially allows females to benefit from acute BA doses; however, effects of an acute BA dose on performance in females remain unknown. The purpose of this investigation was to evaluate how an acute dose of 1.6 g BA affects anaerobic performance in female cyclists. Twelve females (age=26.6±1.3 y) volunteered to participate in this randomized, double-blind study. All participants completed two supplement trials: 1) Placebo=34 g dextrose and 2) BA=1.6 g BA + 34 g dextrose. Thirty-minutes after supplementation, participants performed three repeated Wingate cycling tests with 2 min of active rest after each. Fatigue index, mean power, and peak power were measured during each Wingate. Lactate, heart rate, and rating of perceived exertion (RPE) were measured at rest, immediately after each Wingate, and after each active rest period. RPE significantly decreased (p<0.001) immediately following Wingates 1 and 2 and after each 2-min rest period for the BA trials; however, no differences were observed immediately after Wingate 3 (p>0.05). No significant supplementation effect was observed for any performance or physiological variable (p>0.05 for all variables). Findings suggest that an acute dose of BA (1.6 g) decreases RPE during anaerobic power activities in trained female cyclists.

  18. Effect of aluminium and sulphate on anaerobic digestion of sludge from wastewater enhanced primary treatment.

    PubMed

    Cabirol, N; Barragán, E J; Durán, A; Noyola, A

    2003-01-01

    The combined and individual effects of aluminium and sulphate at concentrations of 1,000 mg/l as Al(OH)3, and 150 mgSO4(2-)/L as K2SO4, respectively, on the anaerobic digestion of sludge from enhanced primary treatment (EPT) were evaluated in 1 L capacity semi continuous reactors. It was found that at 59 days, aluminium inhibits the specific methanogenic activity (SMA) of methanogenic and acetogenic bacteria resulting in a 50% to 72% decrease. Sulphate also inhibits (48% to 65%) the SMA of the same type of bacteria. Methanogenic and acetogenic bacteria were able to adapt, to a different extent, to the assayed concentrations of aluminium and sulphate. However, the combination of aluminium and sulphate resulted in a higher inhibition, especially of the hydrogenophilic methanogenic bacteria. Indeed, this effect remained during the time of the experiment, maintaining an inhibition of 44% at 114 days. Feeding with EPT sludge led to a bigger decrease in SMA of each bacterial group, with respect to the other treatments with time. It is concluded that the acidification of anaerobic reactors fed with EPT sludge is due, among other causes, to the concurrent presence of aluminium and sulphate.

  19. Effect of different livestock dungs as inoculum on food waste anaerobic digestion and its kinetics.

    PubMed

    Dhamodharan, Kondusamy; Kumar, Vikas; Kalamdhad, Ajay S

    2015-03-01

    The aim of this study was to evaluate the effect of different livestock inoculums on the anaerobic digestion of food waste (FW). Five different livestock dungs i.e., poultry dung (PD), goat dung (GD), cow dung (CD), piggery dung (PGD) and rhinoceros dung (RD) were utilized as inoculums and their effects were valued in various food to microorganism (F/M) ratios in batch reactors. Different livestock dungs achieved higher methane production and volatile solids (VS) reduction in different F/M ratios such as PD, GD, CD, PGD and RD achieved at F/M ratio maintained at 1.5, 2, 2, 1.5 and 1.5, respectively. The results indicated that CD and PGD inoculum were more suitable for the anaerobic digestion of FW than other livestock dungs. Reactors inoculated with CD achieved higher methane production (227mLg(-1)VS degraded) and volatile solids degradation (54.58%) at F/M ratio maintained at 2.

  20. Co-digestion of polylactide and kitchen garbage in hyperthermophilic and thermophilic continuous anaerobic process.

    PubMed

    Wang, Feng; Hidaka, Taira; Tsuno, Hiroshi; Tsubota, Jun

    2012-05-01

    Two series of two-phase anaerobic systems, consisting of a hyperthermophilic (80°C) reactor and a thermophilic (55°C) reactor, fed with a mixture of kitchen garbage (KG) and polylactide (PLA), was compared with a single-phase thermophilic reactor for the overall performance. The result indicated that ammonia addition under hyperthermophilic condition promoted the transformation of PLA particles to lactic acid. The systems with hyperthermophilic treatment had advantages on PLA transformation and methane conversion ratio to the control system. Under the organic loading rate (OLR) of 10.3 g COD/(L day), the PLA transformation ratios of the two-phase systems were 82.0% and 85.2%, respectively, higher than that of the control system (63.5%). The methane conversion ratios of the two-phase systems were 82.9% and 80.8%, respectively, higher than 70.1% of the control system. The microbial community analysis indicated that hyperthermophilic treatment is easily installed to traditional thermophilic anaerobic digestion plants without inoculation of special bacteria.

  1. Shotgun metaproteomic profiling of biomimetic anaerobic digestion processes treating sewage sludge.

    PubMed

    Bize, Ariane; Cardona, Laëtitia; Desmond-Le Quéméner, Elie; Battimelli, Audrey; Badalato, Nelly; Bureau, Chrystelle; Madigou, Céline; Chevret, Didier; Guillot, Alain; Monnet, Véronique; Godon, Jean-Jacques; Bouchez, Théodore

    2015-10-01

    Two parallel anaerobic digestion lines were designed to match a "bovid-like" digestive structure. Each of the lines consisted of two continuous stirred tank reactors placed in series and separated by an acidic treatment step. The first line was inoculated with industrial inocula whereas the second was seeded with cow digestive tract contents. After 3 months of continuous sewage sludge feeding, samples were recovered for shotgun metaproteomic and DNA-based analysis. Strikingly, protein-inferred and 16S ribosomal DNA tags based taxonomic community profiles were not consistent. PCA however revealed a similar clustering pattern of the samples, suggesting that reproducible methodological and/or biological factors underlie this observation. The performances of the two digestion lines did not differ significantly and the cow-derived inocula did not establish in the reactors. A low throughput metagenomic dataset (3.4 × 10(6) reads, 1.1 Gb) was also generated for one of the samples. It allowed a substantial increase of the analysis depth (11 vs. 4% of spectral identification rate for the combined samples). Surprisingly, a high proportion of proteins from members of the "Candidatus Competibacter" group, a key microbial player usually found in activated sludge plants, was retrieved in our anaerobic digester samples. Data are available via ProteomeXchange with identifier PXD002420 (http://proteomecentral.proteomexchange.org/dataset/PXD002420).

  2. Co-digestion of polylactide and kitchen garbage in hyperthermophilic and thermophilic continuous anaerobic process.

    PubMed

    Wang, Feng; Hidaka, Taira; Tsuno, Hiroshi; Tsubota, Jun

    2012-05-01

    Two series of two-phase anaerobic systems, consisting of a hyperthermophilic (80°C) reactor and a thermophilic (55°C) reactor, fed with a mixture of kitchen garbage (KG) and polylactide (PLA), was compared with a single-phase thermophilic reactor for the overall performance. The result indicated that ammonia addition under hyperthermophilic condition promoted the transformation of PLA particles to lactic acid. The systems with hyperthermophilic treatment had advantages on PLA transformation and methane conversion ratio to the control system. Under the organic loading rate (OLR) of 10.3 g COD/(L day), the PLA transformation ratios of the two-phase systems were 82.0% and 85.2%, respectively, higher than that of the control system (63.5%). The methane conversion ratios of the two-phase systems were 82.9% and 80.8%, respectively, higher than 70.1% of the control system. The microbial community analysis indicated that hyperthermophilic treatment is easily installed to traditional thermophilic anaerobic digestion plants without inoculation of special bacteria. PMID:22409980

  3. Integrated extraction and anaerobic digestion process for recovery of nutraceuticals and biogas from pomegranate marcs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pomegranate marc (PM), a by-product from pomegranate juice processing, has not been effectively utilized. The objectives of this study were to (1) determine the yields and properties of antioxidants (henceforth referring to total phenolics in terms of tannic acid equivalent) and oil extracted from v...

  4. Enhanced biological phosphorus removal in the retrofitting from an anoxic selector to an anaerobic selector in a full-scale activated sludge process in Singapore.

    PubMed

    Cao, Y; Ang, C M; Chua, K C; Woo, F W; Chi, H; Bhawna, B; Chong, C T; Ganesan, N; Ooi, K E; Wah, Y L

    2009-01-01

    This paper presents the investigation results of retrofitting an anoxic selector to an anaerobic selector through stepwise reduction of air supply in a full-scale activated sludge process with a focus on enhanced biological phosphorus removal (EBPR). The process experienced gradual shift from a Ludzack-Ettinger (LE) to an anaerobic-anoxic-oxic (A(2)O) process and subsequently, an anaerobic-oxic (A/O) process. The major findings are: (i) the average influent-based PO(4) (3-)-P release in the anaerobic selector compartment was 16.3 mg P l(-1) and that in the secondary clarifier was 1.7 mg P l(-1). 75% of the SCOD and 93% of the acetic acid in the primary effluent were taken up in the anaerobic selector compartment, respectively; (ii) PO(4) (3-)-P uptake contributed by both aerobic and denitrifying phosphorus accumulating organisms (DPAOs) occurred mainly in the first and second aerobic lanes together with simultaneous nitrification and denitrification (SND) while there was not much contribution from the last aerobic lane; (iii) The average PO(4) (3-)-P concentration of the final effluent was 2.4 mg P l(-1) corresponding to a removal efficiency of 85%; (iv) the SVI was satisfactory after retrofitting; and (v) the increase of NH(4) (+)-N in the final effluent from the commencement to the completion of the retrofitting resulted in an approximate 40-50% reduction in oxygen demand and a significant aeration energy saving was achieved.

  5. The effect of lactic acid on anaerobic carbon or nitrogen limited chemostat cultures of Saccharomyces cerevisiae.

    PubMed

    Thomsson, Elisabeth; Larsson, Christer

    2006-07-01

    Weak organic acids are well-known metabolic effectors in yeast and other micro-organisms. High concentrations of lactic acid due to infection of lactic acid bacteria often occurs in combination with growth under nutrient-limiting conditions in industrial yeast fermentations. The effects of lactic acid on growth and product formation of Saccharomyces cerevisiae were studied, with cells growing under carbon- or nitrogen-limiting conditions in anaerobic chemostat cultures (D=0.1 h(-1)) at pH values 3.25 and 5. It was shown that lactic acid in industrially relevant concentrations had a rather limited effect on the metabolism of S. cerevisiae. However, there was an effect on the energetic status of the cells, i.e. lactic acid addition provoked a reduction in the adenosine triphosphate (ATP) content of the cells. The decrease in ATP was not accompanied by a significant increase in the adenosine monophosphate levels.

  6. pH Control for Effective Anaerobic Bioremediation of Chlorinated Solvents

    NASA Astrophysics Data System (ADS)

    Robinson, C.; Barry, D.; Gerhard, J. I.; Kouznetsova, I.

    2007-12-01

    SABRE (Source Area BioREmediation) is a 4-year collaborative project that aims to evaluate the performance of enhanced anaerobic bioremediation for the treatment of chlorinated solvent DNAPL source areas. The project focuses on a pilot scale demonstration at a trichloroethene (TCE) DNAPL field site, and includes complementary laboratory and modelling studies. Organic acids and hydrogen ions (HCl) typically build up in the treatment zone during anaerobic bioremediation. In aquifer systems with relatively low buffering capacity the generation of these products can cause significant groundwater acidification thereby inhibiting dehalogenating activity. Where the soil buffering capacity is exceeded, addition of buffer may be needed for the effective continuation of TCE degradation. As an aid to the design of remediation schemes, a geochemical model was designed to predict the amount of buffer required to maintain the source zone pH at a suitable level for dechlorinating bacteria (i.e. > 6.5). The model accounts for the amount of TCE to be degraded, site water chemistry, type of organic amendment and soil mineralogy. It assumes complete dechlorination of TCE, and further considers mineral dissolution and precipitation kinetics. The model is applicable to a wide range of sites. For illustration we present results pertinent to the SABRE field site. Model results indicate that, for the extensive dechlorination expected in proximity to the SABRE DNAPL source zone, significant buffer addition may be necessary. Additional simulations are performed to identify buffer requirements over a wider range of field conditions.

  7. Effects of Intermittent Training on Anaerobic Performance and MCT Transporters in Athletes

    PubMed Central

    Millet, Grégoire; Bentley, David J.; Roels, Belle; Mc Naughton, Lars R.; Mercier, Jacques; Cameron-Smith, David

    2014-01-01

    This study examined the effects of intermittent hypoxic training (IHT) on skeletal muscle monocarboxylate lactate transporter (MCT) expression and anaerobic performance in trained athletes. Cyclists were assigned to two interventions, either normoxic (N; n = 8; 150 mmHg PIO2) or hypoxic (H; n = 10; ∼3000 m, 100 mmHg PIO2) over a three week training (5×1 h-1h30.week−1) period. Prior to and after training, an incremental exercise test to exhaustion (EXT) was performed in normoxia together with a 2 min time trial (TT). Biopsy samples from the vastus lateralis were analyzed for MCT1 and MCT4 using immuno-blotting techniques. The peak power output (PPO) increased (p<0.05) after training (7.2% and 6.6% for N and H, respectively), but VO2max showed no significant change. The average power output in the TT improved significantly (7.3% and 6.4% for N and H, respectively). No differences were found in MCT1 and MCT4 protein content, before and after the training in either the N or H group. These results indicate there are no additional benefits of IHT when compared to similar normoxic training. Hence, the addition of the hypoxic stimulus on anaerobic performance or MCT expression after a three-week training period is ineffective. PMID:24797797

  8. Anaerobic digestion of food waste - Effect of recirculation and temperature on performance and microbiology.

    PubMed

    Zamanzadeh, Mirzaman; Hagen, Live H; Svensson, Kine; Linjordet, Roar; Horn, Svein J

    2016-06-01

    Recirculation of digestate was investigated as a strategy to dilute the food waste before feeding to anaerobic digesters, and its effects on microbial community structure and performance were studied. Two anaerobic digesters with digestate recirculation were operated at 37 °C (MD + R) and 55 °C (TD + R) and compared to two additional digesters without digestate recirculation operated at the same temperatures (MD and TD). The MD + R digester demonstrated quite stable and similar performance to the MD digester in terms of the methane yield (around 480 mL CH4 per gVSadded). In both MD and MD + R Methanosaeta was the dominant archaea. However, the bacterial community structure was significantly different in the two digesters. Firmicutes dominated in the MD + R, while Chloroflexi was the dominant phylum in the MD. Regarding the thermophilic digesters, the TD + R showed the lowest methane yield (401 mL CH4 per gVSadded) and accumulation of VFAs. In contrast to the mesophilic digesters, the microbial communities in the thermophilic digesters were rather similar, consisting mainly of the phyla Firmicutes, Thermotoga, Synergistetes and the hydrogenotrophic methanogen Methanothermobacter. The impact of ammonia inhibition was different depending on the digesters configurations and operating temperatures.

  9. Effect of chemo-mechanical disintegration on sludge anaerobic digestion for enhanced biogas production.

    PubMed

    Kavitha, S; Pray, S Saji; Yogalakshmi, K N; Kumar, S Adish; Yeom, Ick-Tae; Banu, J Rajesh

    2016-02-01

    The effect of combined surfactant-dispersion pretreatment on dairy waste activated sludge (WAS) reduction in anaerobic digesters was investigated. The experiments were performed with surfactant, Sodium dodecyl sulfate (SDS) in the range of 0.01 to 0.1 g/g suspended solids (SS) and disperser with rpm of 5000-25,000. The COD (chemical oxygen demand) solubilization, suspended solids reduction, and biogas generation increased for an energy input of 7377 kJ/kg total solids (TS) (12,000 rpm, 0.04 g/g SS, and 30 min) and were found to be 38, 32, and 75 %, higher than that of control. The pretreated sludge improved the performance of semicontinuous anaerobic digesters of 4 L working volume operated at four different SRTs (sludge retention time). SRT of 15 days was found to be appropriate showing 49 and 51 % reduction in SS and volatile solids (VS), respectively. The methane yield of the pretreated sample was observed to be 50 mL/g VS removed which was observed to be comparatively higher than the control (12 mL/g VS removed) at optimal SRT of 15 days. To the best of the authors' knowledge, this study is the first to be reported and not yet been documented in literature.

  10. Effects of lactone, ketone, and phenolic compounds on methane production and metabolic intermediates during anaerobic digestion.

    PubMed

    Wikandari, Rachma; Sari, Noor Kartika; A'yun, Qurrotul; Millati, Ria; Cahyanto, Muhammad Nur; Niklasson, Claes; Taherzadeh, Mohammad J

    2015-02-01

    Fruit waste is a potential feedstock for biogas production. However, the presence of fruit flavors that have antimicrobial activity is a challenge for biogas production. Lactones, ketones, and phenolic compounds are among the several groups of fruit flavors that are present in many fruits. This work aimed to investigate the effects of two lactones, i.e., γ-hexalactone and γ-decalactone; two ketones, i.e., furaneol and mesifurane; and two phenolic compounds, i.e., quercetin and epicatechin on anaerobic digestion with a focus on methane production, biogas composition, and metabolic intermediates. Anaerobic digestion was performed in a batch glass digester incubated at 55 °C for 30 days. The flavor compounds were added at concentrations of 0.05, 0.5, and 5 g/L. The results show that the addition of γ-decalactone, quercetin, and epicathechin in the range of 0.5-5 g/L reduced the methane production by 50 % (MIC50). Methane content was reduced by 90 % with the addition of 5 g/L of γ-decalactone, quercetin, and epicathechin. Accumulation of acetic acid, together with an increase in carbon dioxide production, was observed. On the contrary, γ-hexalactone, furaneol, and mesifurane increased the methane production by 83-132 % at a concentration of 5 g/L.

  11. Improve bio-activity of anaerobic sludge by low energy ultrasound.

    PubMed

    Zhu, Yichun; Li, Xin; Du, Maoan; Liu, Zuwen; Luo, Hui; Zhang, Tao

    2015-01-01

    This research focused on ultrasound-enhanced bio-activity of anaerobic sludge. Low energy ultrasound irradiation can increase the bio-activity of anaerobic sludge. Ultrasonic parameter, characteristics of anaerobic sludge and experimental conditions are important parameters which affect the enhancement effect on anaerobic sludge. In order to assess the effects of characteristics of anaerobic sludge and experimental conditions on ultrasonic irradiation of anaerobic sludge, experiments with different characteristics of anaerobic sludge were carried out and analyzed with the content of coenzyme F420 and dehydrogenase activity (DHA). The results showed that anaerobic sludge bio-activity was impacted by the initial temperature, initial chemical oxygen demand (COD), sludge concentration, and stirring during the ultrasonic process. Optimal performance was achieved when sound frequency, power density, and ultrasonic irradiation period was 20 kHz, 0.1 W/mL, and 10 min, respectively, under which the wastewater COD removal efficiency was increased by 12.9 percentage points. The results indicated that low temperature could affect the anaerobic sludge irradiation effect, while intermittent stirring could enhance the bio-activity of anaerobic sludge irradiation effect and low substrate concentration improved anaerobic sludge activity by ultrasound. PMID:26676010

  12. Improve bio-activity of anaerobic sludge by low energy ultrasound.

    PubMed

    Zhu, Yichun; Li, Xin; Du, Maoan; Liu, Zuwen; Luo, Hui; Zhang, Tao

    2015-01-01

    This research focused on ultrasound-enhanced bio-activity of anaerobic sludge. Low energy ultrasound irradiation can increase the bio-activity of anaerobic sludge. Ultrasonic parameter, characteristics of anaerobic sludge and experimental conditions are important parameters which affect the enhancement effect on anaerobic sludge. In order to assess the effects of characteristics of anaerobic sludge and experimental conditions on ultrasonic irradiation of anaerobic sludge, experiments with different characteristics of anaerobic sludge were carried out and analyzed with the content of coenzyme F420 and dehydrogenase activity (DHA). The results showed that anaerobic sludge bio-activity was impacted by the initial temperature, initial chemical oxygen demand (COD), sludge concentration, and stirring during the ultrasonic process. Optimal performance was achieved when sound frequency, power density, and ultrasonic irradiation period was 20 kHz, 0.1 W/mL, and 10 min, respectively, under which the wastewater COD removal efficiency was increased by 12.9 percentage points. The results indicated that low temperature could affect the anaerobic sludge irradiation effect, while intermittent stirring could enhance the bio-activity of anaerobic sludge irradiation effect and low substrate concentration improved anaerobic sludge activity by ultrasound.

  13. Fate of Zinc Oxide Nanoparticles during Anaerobic Digestion of Wastewater and Post-Treatment Processing of Sewage Sludge

    SciTech Connect

    Lombi, Enzo; Donner, Erica; Tavakkoli, Ehsan; Turney, Terence W.; Naidu, Ravi; Miller, Bradley W.; Scheckel, Kirk G.

    2013-01-14

    The rapid development and commercialization of nanomaterials will inevitably result in the release of nanoparticles (NPs) to the environment. As NPs often exhibit physical and chemical properties significantly different from those of their molecular or macrosize analogs, concern has been growing regarding their fate and toxicity in environmental compartments. The wastewater-sewage sludge pathway has been identified as a key release pathway leading to environmental exposure to NPs. In this study, we investigated the chemical transformation of two ZnO-NPs and one hydrophobic ZnO-NP commercial formulation (used in personal care products), during anaerobic digestion of wastewater. Changes in Zn speciation as a result of postprocessing of the sewage sludge, mimicking composting/stockpiling, were also assessed. The results indicated that 'native' Zn and Zn added either as a soluble salt or as NPs was rapidly converted to sulfides in all treatments. The hydrophobicity of the commercial formulation retarded the conversion of ZnO-NP. However, at the end of the anaerobic digestion process and after postprocessing of the sewage sludge (which caused a significant change in Zn speciation), the speciation of Zn was similar across all treatments. This indicates that, at least for the material tested, the risk assessment of ZnO-NP through this exposure pathway can rely on the significant knowledge already available in regard to other 'conventional' forms of Zn present in sewage sludge.

  14. Application and kinetic evaluation of upflow anaerobic biofilm reactor for nitrogen removal from wastewater by Anammox process

    PubMed Central

    2013-01-01

    The lab-scale upflow anaerobic biofilm reactor was successfully operated for the treatment of synthetic wastewater with high nitrogen load by Anammox (anaerobic ammonium oxidation) process. During the entire period of operation, the reactor temperature was kept at 35±1°C. The operational strategy consisted of both increasing the ammonium and nitrite concentrations from 60 to 700mgN/L and from 80 to 920 mgN/L, respectively and decreasing the hydraulic retention time from 24 to 6 h, at each step. The highest achieved removal efficiency of ammonium and nitrite were 91 and 93%, respectively. Consequently, due to their acceptable performance for nitrogen removal in previous researches, modified Stover-Kincannon and Grau second-order models were used in this study. According to the experiment results, the model validity testing showed that the Stover-Kincannon model was a little more appropriate for the description of nitrogen removal in the reactor, even though both models gave high correlation coefficients (R2=0.999). PMID:23414202

  15. Combined anaerobic-aerobic and UV/H2O2 processes for the treatment of synthetic slaughterhouse wastewater.

    PubMed

    Bustillo-Lecompte, Ciro Fernando; Mehrvar, Mehrab; Quiñones-Bolaños, Edgar

    2013-01-01

    The biological treatment of a synthetic slaughterhouse wastewater (SSWW) is studied using an anaerobic baffled bioreactor (ABR) and an aerobic activated sludge (AS) at a laboratory scale in continuous mode. The total organic carbon (TOC) loading rate, the total nitrogen (TN) loading rate, and the flow rate are 0.03-1.01 g/(L.day), 0.01-0.19 g/(L.day), and 2.93-11.70 mL/min, respectively. The results reveal that combined anaerobic-aerobic processes had higher efficiency to treat SSWW than a single process. Up to 96.36% TOC, 80.53% TN, and 99.38% 5-day carbonaceous biochemical oxygen demand (CBOD5) removal from an influent concentration of 1,009 mgTOC/L, 420 mgTN/L, and 640 mgCBOD5/L at the hydraulic retention time (HRT) of 6.24 days and a flow rate of 3.75 mL/min are achieved. The UV/H2O2 process is studied to treat a secondary effluent of SSWW with TOC loadings of 65-350 mg/L. Up to 75.22% TOC and 84.38% CBOD5 removal are obtained at the HRT of 3 h with H2O2 concentration of 900 mg/L. Optimum molar ratios of 13.87 mgH2O2/mgTOCin and 4.62 mgH2O2/mgTOCin.h are also obtained. Combined anaerobic-aerobic and UV/H2O2 processes enhanced the biodegradability of the TOC, TN, and CBOD5 present in the SSWW. Up to 99.98% TOC, 82.84% TN, and 99.69% CBOD5 overall removals are obtained for an influent concentration of 1,005 mgTOC/L, 200 mgTN/L, and 640 mgCBOD5/L at the HRT of 4 days and a flow-rate of 5.90 mL/min.

  16. The anaerobic degradation of gaseous, nonmethane alkanes — From in situ processes to microorganisms

    PubMed Central

    Musat, Florin

    2015-01-01

    The short chain, gaseous alkanes ethane, propane, n- and iso-butane are released in significant amounts into the atmosphere, where they contribute to tropospheric chemistry and ozone formation. Biodegradation of gaseous alkanes by aerobic microorganisms, mostly bacteria and fungi isolated from terrestrial environments, has been known for several decades. The first indications for short chain alkane anaerobic degradation were provided by geochemical studies of deep-sea environments around hydrocarbon seeps, and included the uncoupling of the sulfate-reduction and anaerobic oxidation of methane rates, the consumption of gaseous alkanes in anoxic sediments, or the enrichment in 13C of gases in interstitial water vs. the source gas. Microorganisms able to degrade gaseous alkanes were recently obtained from deep-sea and terrestrial sediments around hydrocarbon seeps. Up to date, only sulfate-reducing pure or enriched cultures with ethane, propane and n-butane have been reported. The only pure culture presently available, strain BuS5, is affiliated to the Desulfosarcina–Desulfococcus cluster of the Deltaproteobacteria. Other phylotypes involved in gaseous alkane degradation have been identified based on stable-isotope labeling and whole-cell hybridization. Under anoxic conditions, propane and n-butane are activated similar to the higher alkanes, by homolytic cleavage of the C—H bond of a subterminal carbon atom, and addition of the ensuing radical to fumarate, yielding methylalkylsuccinates. An additional mechanism of activation at the terminal carbon atoms was demonstrated for propane, which could in principle be employed also for the activation of ethane. PMID:25904994

  17. The anaerobic degradation of gaseous, nonmethane alkanes - From in situ processes to microorganisms.

    PubMed

    Musat, Florin

    2015-01-01

    The short chain, gaseous alkanes ethane, propane, n- and iso-butane are released in significant amounts into the atmosphere, where they contribute to tropospheric chemistry and ozone formation. Biodegradation of gaseous alkanes by aerobic microorganisms, mostly bacteria and fungi isolated from terrestrial environments, has been known for several decades. The first indications for short chain alkane anaerobic degradation were provided by geochemical studies of deep-sea environments around hydrocarbon seeps, and included the uncoupling of the sulfate-reduction and anaerobic oxidation of methane rates, the consumption of gaseous alkanes in anoxic sediments, or the enrichment in (13)C of gases in interstitial water vs. the source gas. Microorganisms able to degrade gaseous alkanes were recently obtained from deep-sea and terrestrial sediments around hydrocarbon seeps. Up to date, only sulfate-reducing pure or enriched cultures with ethane, propane and n-butane have been reported. The only pure culture presently available, strain BuS5, is affiliated to the Desulfosarcina-Desulfococcus cluster of the Deltaproteobacteria. Other phylotypes involved in gaseous alkane degradation have been identified based on stable-isotope labeling and whole-cell hybridization. Under anoxic conditions, propane and n-butane are activated similar to the higher alkanes, by homolytic cleavage of the C-H bond of a subterminal carbon atom, and addition of the ensuing radical to fumarate, yielding methylalkylsuccinates. An additional mechanism of activation at the terminal carbon atoms was demonstrated for propane, which could in principle be employed also for the activation of ethane. PMID:25904994

  18. Temperature Adaptations in the Terminal Processes of Anaerobic Decomposition of Yellowstone National Park and Icelandic Hot Spring Microbial Mats

    PubMed Central

    Sandbeck, Kenneth A.; Ward, David M.

    1982-01-01

    The optimum temperatures for methanogenesis in microbial mats of four neutral to alkaline, low-sulfate hot springs in Yellowstone National Park were between 50 and 60°C, which was 13 to 23°C lower than the upper temperature for mat development. Significant methanogenesis at 65°C was only observed in one of the springs. Methane production in samples collected at a 51 or 62°C site in Octopus Spring was increased by incubation at higher temperatures and was maximal at 70°C. Strains of Methanobacterium thermoautotrophicum were isolated from 50, 55, 60, and 65°C sites in Octopus Spring at the temperatures of the collection sites. The optimum temperature for growth and methanogenesis of each isolate was 65°C. Similar results were found for the potential rate of sulfate reduction in an Icelandic hot spring microbial mat in which sulfate reduction dominated methane production as a terminal process in anaerobic decomposition. The potential rate of sulfate reduction along the thermal gradient of the mat was greatest at 50°C, but incubation at 60°C of the samples obtained at 50°C increased the rate. Adaptation to different mat temperatures, common among various microorganisms and processes in the mats, did not appear to occur in the processes and microorganisms which terminate the anaerobic food chain. Other factors must explain why the maximal rates of these processes are restricted to moderate temperatures of the mat ecosystem. PMID:16346109

  19. The effects of aerobic and anaerobic exercise conditioning on resting metabolic rate and the thermic effect of a meal.

    PubMed

    Schmidt, W D; Hyner, G C; Lyle, R M; Corrigan, D; Bottoms, G; Melby, C L

    1994-12-01

    This study examined resting metabolic rate (RMR) and thermic effect of a meal (TEM) among athletes who had participated in long-term anaerobic or aerobic exercise. Nine collegiate wrestlers were matched for age, weight, and fat-free weight with 9 collegiate swimmers. Preliminary testing included maximal oxygen consumption, maximal anaerobic capacity (MAnC) for both the arms and the legs, and percent body fat. On two separate occasions, RMR and TEM were measured using indirect calorimetry. VO2max was significantly higher in the swimmers while MAnC was significantly higher in the wrestlers for both the arms and the legs. RMR adjusted for fat-free weight was not significantly different between groups. The differences in total and percentage of TEM between the groups were not statistically significant, and there were no differences in baseline thyroid hormones. These data suggest that despite significant differences in VO2max and WAnT values following long-term aerobic and anaerobic exercise training, resting energy expenditure does not differ between these college athletes. PMID:7874150

  20. Mathematical model of anaerobic digestion in a chemostat: effects of syntrophy and inhibition.

    PubMed

    Weedermann, Marion; Seo, Gunog; Wolkowicz, Gail S K

    2013-01-01

    Three of the four main stages of anaerobic digestion: acidogenesis, acetogenesis, and methanogenesis are described by a system of differential equations modelling the interaction of microbial populations in a chemostat. The microbes consume and/or produce simple substrates, alcohols and fatty acids, acetic acid, and hydrogen. Acetogenic bacteria and hydrogenotrophic methanogens interact through syntrophy. The model also includes the inhibition of acetoclastic and hydrogenotrophic methanogens due to sensitivity to varying pH-levels. To examine the effects of these interactions and inhibitions, we first study an inhibition-free model and obtain results for global stability using differential inequalities together with conservation laws. For the model with inhibition, we derive conditions for existence, local stability, and bistability of equilibria and present a global stability result. A case study illustrates the effects of inhibition on the regions of stability. Inhibition introduces regions of bistability and stabilizes some equilibria.

  1. Effect of urea addition on giant reed ensilage and subsequent methane production by anaerobic digestion.

    PubMed

    Liu, Shan; Ge, Xumeng; Liew, Lo Niee; Liu, Zhe; Li, Yebo

    2015-09-01

    The effect of urea addition on giant reed ensilage and sequential anaerobic digestion (AD) of the ensiled giant reed was evaluated. The dry matter loss during ensilage (up to 90 days) with or without urea addition was about 1%. Addition of 2% urea enhanced production of lactic acid by about 4 times, and reduced production of propionic acid by 2-8 times. Besides, urea addition reduced degradation of cellulose and hemicellulose, and increased degradation of lignin in giant reed during ensilage. Ensilage with or without urea addition had no significant effects on the enzymatic digestibility of giant reed, but ensilage with urea addition achieved a cumulative methane yield of 173 L/kg VS, which was 18% higher than that of fresh giant reed. The improved methane yield of giant reed could be attributed to the production of organic acids and ethanol during ensilage.

  2. Mathematical model of anaerobic digestion in a chemostat: effects of syntrophy and inhibition

    PubMed Central

    Weedermann, Marion; Seo, Gunog; Wolkowicz, Gail S.K.

    2013-01-01

    Three of the four main stages of anaerobic digestion: acidogenesis, acetogenesis, and methanogenesis are described by a system of differential equations modelling the interaction of microbial populations in a chemostat. The microbes consume and/or produce simple substrates, alcohols and fatty acids, acetic acid, and hydrogen. Acetogenic bacteria and hydrogenotrophic methanogens interact through syntrophy. The model also includes the inhibition of acetoclastic and hydrogenotrophic methanogens due to sensitivity to varying pH-levels. To examine the effects of these interactions and inhibitions, we first study an inhibition-free model and obtain results for global stability using differential inequalities together with conservation laws. For the model with inhibition, we derive conditions for existence, local stability, and bistability of equilibria and present a global stability result. A case study illustrates the effects of inhibition on the regions of stability. Inhibition introduces regions of bistability and stabilizes some equilibria. PMID:23336708

  3. Osmotic pressure effect on membrane fouling in a submerged anaerobic membrane bioreactor and its experimental verification.

    PubMed

    Chen, Jianrong; Zhang, Meijia; Wang, Aijun; Lin, Hongjun; Hong, Huachang; Lu, Xiaofeng

    2012-12-01

    A laboratory-scale submerged anaerobic membrane bioreactor (SAnMBR) treating sewage was used to investigate the membrane fouling mechanism. Characterization of cake layer formed on membrane surface showed that cake layer was hydrated, rich of extracellular polymeric substances (EPS) and negative charged with the charge density of 0.21-0.46 meq/kg MLSS. Detailed analysis revealed a new membrane fouling mechanism, osmotic pressure during cake layer filtration process due to the interception of ions. An osmotic pressure model was then developed to elaborate the existence of osmotic pressure and to estimate the contribution of osmotic pressure to membrane fouling. The calculated results showed that osmotic pressure accounted for the largest fraction of total operation pressure, indicating that osmotic pressure generated by the retained ions was one of the major mechanisms responsible for membrane fouling problem in MBRs. These findings provided a new insight into membrane fouling in MBRs. PMID:23026319

  4. Manipulation of step height and its effect on lactate metabolism during a one-minute anaerobic step test.

    PubMed

    Nguyen, Brian D; Gillum, Trevor L

    2015-06-01

    The purpose of this study was to observe the effects of the 1-minute anaerobic step test on lactate production. In addition, a comparison of postexercise lactate levels between the traditional 40-cm step height and a modified 20-cm step height was tested along with multiple biomechanical components such as torque, knee angle, and power. A convenience sample of 9 healthy moderately trained individuals were recruited for this experiment. Each subject performed the 1-minute anaerobic step test in a counterbalanced, crossover, and repeated-measures design. They performed 2 trials, 1 with a 40-cm step height and another with a 20-cm step height. Results showed statistical significance in terms of the postexercise lactate concentration (40 cm: 8.04 ± 2.13 mmol·L(-1); 20 cm: 6.18 ± 2.62 mmol·L(-1)) and lactate production (40 cm: 5.36 ± 2.73 mmol·L(-1); 20 cm: 3.06 ± 2.96 mmol·L(-1)) between the 2 step heights (p ≤ 0.05). With a lowered step height, the moment arm decreased significantly, which lowered the torque placed on the knee joint. Knee angle and power both decreased with a lowered step height of 20 cm. These results suggest that the 1-minute anaerobic step test is effective at eliciting lactate and can be used as an anaerobic exercise modality to train the anaerobic energy system. Furthermore, a step height of 40 cm seemed to be more effective at taxing the anaerobic energy system and eliciting lactate compared with a step height of 20 cm.

  5. The control of H2S in biogas using iron ores as in situ desulfurizers during anaerobic digestion process.

    PubMed

    Zhou, Qiying; Jiang, Xia; Li, Xi; Jiang, Wenju

    2016-09-01

    In this study, five kinds of iron ores, limonite, hematite, manganese ore, magnetite and lava rock, were used as the in situ desulfurizers in the anaerobic digestion reactors to investigate their effects on controlling H2S in biogas. The results show that the addition of the five iron ores could significantly control the content of H2S in biogas, with the best performance for limonite. As limonite dosages increase (10-60 g/L), the contents of H2S in biogas were evidently decreased in the digesters with different initial sulfate concentrations (0-1000 mg/L). After the anaerobic digestion, the removed sulfur was mostly deposited on the surface of limonite. A possible mechanism of H2S control in biogas by limonite was proposed preliminarily, including adsorption, FeS precipitation, and Fe (III) oxidation. The results demonstrated that limonite was a promising in situ desulfurizer for controlling H2S in biogas with low cost and high efficiency. PMID:27209038

  6. 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.

  7. Treatment of food processing wastewater in a full-scale jet biogas internal loop anaerobic fluidized bed reactor.

    PubMed

    Wei, Chaohai; Zhang, Tao; Feng, Chunhua; Wu, Haizhen; Deng, Zhiyi; Wu, Chaofei; Lu, Bin

    2011-04-01

    A full-scale jet biogas internal loop anaerobic fluidized bed (JBILAFB) reactor, which requires low energy input and allows enhanced mass transfer, was constructed for the treatment of food processing wastewater. This reactor has an active volume of 798 m(3) and can treat 33.3 m(3) wastewater per hour. After pre-treating the raw wastewater by settling, oil separating and coagulation-air floating processes, the reactor was operated with a relatively shorter start-up time (55 days). Samples for the influent and effluent of the JBILAFB reactor were taken and analyzed daily for the whole process including both the start-up and stable running periods. When the volumetric COD loading fluctuated in the range of 1.6-5.6 kg COD m(-3) day(-1), the COD removal efficiency, the volatile fatty acid(VFA)/alkalinity ratio, the maximum biogas production and the content of CH(4) in total biogas of the reactor were found to be 80.1 ± 5%, 0.2-0.5, 348.5 m(3 )day(-1) and 94.5 ± 2.5%, respectively. Furthermore, the scanning electron microscope (SEM) results showed that anaerobic granular sludge and microorganism particles with biofilm coexisted in the reactor, and that the bacteria mainly in bacilli and cocci were observed as predominant species. All the data demonstrated that the enhanced mass transfer for gas, liquid and solid phases was achieved, and that the formation of microorganism granules and the removal of inhibitors increased the stability of the system.

  8. Evidence for the cooccurrence of nitrite-dependent anaerobic ammonium and methane oxidation processes in a flooded paddy field.

    PubMed

    Shen, Li-Dong; Liu, Shuai; Huang, Qian; Lian, Xu; He, Zhan-Fei; Geng, Sha; Jin, Ren-Cun; He, Yun-Feng; Lou, Li-Ping; Xu, Xiang-Yang; Zheng, Ping; Hu, Bao-Lan

    2014-12-01

    Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two of the most recent discoveries in the microbial nitrogen cycle. In the present study, we provide direct evidence for the cooccurrence of the anammox and n-damo processes in a flooded paddy field in southeastern China. Stable isotope experiments showed that the potential anammox rates ranged from 5.6 to 22.7 nmol N2 g(-1) (dry weight) day(-1) and the potential n-damo rates varied from 0.2 to 2.1 nmol CO2 g(-1) (dry weight) day(-1) in different layers of soil cores. Quantitative PCR showed that the abundance of anammox bacteria ranged from 1.0 × 10(5) to 2.0 × 10(6) copies g(-1) (dry weight) in different layers of soil cores and the abundance of n-damo bacteria varied from 3.8 × 10(5) to 6.1 × 10(6) copies g(-1) (dry weight). Phylogenetic analyses of the recovered 16S rRNA gene sequences showed that anammox bacteria affiliated with "Candidatus Brocadia" and "Candidatus Kuenenia" and n-damo bacteria related to "Candidatus Methylomirabilis oxyfera" were present in the soil cores. It is estimated that a total loss of 50.7 g N m(-2) per year could be linked to the anammox process, which is at intermediate levels for the nitrogen flux ranges of aerobic ammonium oxidation and denitrification reported in wetland soils. In addition, it is estimated that a total of 0.14 g CH4 m(-2) per year could be oxidized via the n-damo process, while this rate is at the lower end of the aerobic methane oxidation rates reported in wetland soils.

  9. Effect of ammoniacal nitrogen on one-stage and two-stage anaerobic digestion of food waste

    SciTech Connect

    Ariunbaatar, Javkhlan; Scotto Di Perta, Ester; Panico, Antonio; Frunzo, Luigi; Esposito, Giovanni; Lens, Piet N.L.; Pirozzi, Francesco

    2015-04-15

    Highlights: • Almost 100% of the biomethane potential of food waste was recovered during AD in a two-stage CSTR. • Recirculation of the liquid fraction of the digestate provided the necessary buffer in the AD reactors. • A higher OLR (0.9 gVS/L·d) led to higher accumulation of TAN, which caused more toxicity. • A two-stage reactor is more sensitive to elevated concentrations of ammonia. • The IC{sub 50} of TAN for the AD of food waste amounts to 3.8 g/L. - Abstract: This research compares the operation of one-stage and two-stage anaerobic continuously stirred tank reactor (CSTR) systems fed semi-continuously with food waste. The main purpose was to investigate the effects of ammoniacal nitrogen on the anaerobic digestion process. The two-stage system gave more reliable operation compared to one-stage due to: (i) a better pH self-adjusting capacity; (ii) a higher resistance to organic loading shocks; and (iii) a higher conversion rate of organic substrate to biomethane. Also a small amount of biohydrogen was detected from the first stage of the two-stage reactor making this system attractive for biohythane production. As the digestate contains ammoniacal nitrogen, re-circulating it provided the necessary alkalinity in the systems, thus preventing an eventual failure by volatile fatty acids (VFA) accumulation. However, re-circulation also resulted in an ammonium accumulation, yielding a lower biomethane production. Based on the batch experimental results the 50% inhibitory concentration of total ammoniacal nitrogen on the methanogenic activities was calculated as 3.8 g/L, corresponding to 146 mg/L free ammonia for the inoculum used for this research. The two-stage system was affected by the inhibition more than the one-stage system, as it requires less alkalinity and the physically separated methanogens are more sensitive to inhibitory factors, such as ammonium and propionic acid.

  10. Anaerobic Thermophiles

    PubMed Central

    Canganella, Francesco; Wiegel, Juergen

    2014-01-01

    The term “extremophile” was introduced to describe any organism capable of living and growing under extreme conditions. With the further development of studies on microbial ecology and taxonomy, a variety of “extreme” environments have been found and an increasing number of extremophiles are being described. Extremophiles have also been investigated as far as regarding the search for life on other planets and even evaluating the hypothesis that life on Earth originally came from space. The first extreme environments to be largely investigated were those characterized by elevated temperatures. The naturally “hot environments” on Earth range from solar heated surface soils and water with temperatures up to 65 °C, subterranean sites such as oil reserves and terrestrial geothermal with temperatures ranging from slightly above ambient to above 100 °C, to submarine hydrothermal systems with temperatures exceeding 300 °C. There are also human-made environments with elevated temperatures such as compost piles, slag heaps, industrial processes and water heaters. Thermophilic anaerobic microorganisms have been known for a long time, but scientists have often resisted the belief that some organisms do not only survive at high temperatures, but actually thrive under those hot conditions. They are perhaps one of the most interesting varieties of extremophilic organisms. These microorganisms can thrive at temperatures over 50 °C and, based on their optimal temperature, anaerobic thermophiles can be subdivided into three main groups: thermophiles with an optimal temperature between 50 °C and 64 °C and a maximum at 70 °C, extreme thermophiles with an optimal temperature between 65 °C and 80 °C, and finally hyperthermophiles with an optimal temperature above 80 °C and a maximum above 90 °C. The finding of novel extremely thermophilic and hyperthermophilic anaerobic bacteria in recent years, and the fact that a large fraction of them belong to the Archaea has

  11. Mesophilic anaerobic co-digestion of poultry dropping and Carica papaya peels: Modelling and process parameter optimization study.

    PubMed

    Dahunsi, S O; Oranusi, S; Owolabi, J B; Efeovbokhan, V E

    2016-09-01

    The study evaluated anaerobic co-digestion of poultry dropping and pawpaw peels and the optimization of important process parameters. The physic-chemical analyses of the substrates were done using standard methods after application of mechanical, thermal and chemical pre-treatments methods. Gas chromatography analysis revealed the gas composition to be within the range of 66-68% methane and 18-23% carbon dioxide. The study equally revealed that combination of the different pre-treatment methods enhanced enormous biogas yield from the digestion. Optimization of the generated biogas data were carried out using the Response Surface Methodology and the Artificial Neural Networks. The coefficient of determination (R(2)) for RSM (0.9181) was lower compare to that of ANN (0.9828). This shows that ANN model gives higher accuracy than RSM model for the current. Further usage of Carica papaya peels for biogas generation is advocated.

  12. Treatment of wastewater from coffee bean processing in anaerobic fixed bed reactors with different support materials: performance and kinetic modeling.

    PubMed

    Fia, Fátima R L; Matos, Antonio T; Borges, Alisson C; Fia, Ronaldo; Cecon, Paulo R

    2012-10-15

    An evaluation was performed of three upflow anaerobic fixed bed reactors for the treatment of wastewater from coffee bean processing (WCP). The supports used were: blast furnace cinders, polyurethane foam and crushed stone with porosities of 53, 95 and 48%, respectively. The testing of these 139.5 L reactors consisted of increasing the COD of the influent (978; 2401 and 4545 mg L(-1)), while maintaining the retention time of 1.3 days. For the maximum COD applied, the reactor filled with foam presented removals of 80% (non-filtered samples) and 83% (filtered samples). The greater performance of the reactor filled with foam is attributed to its porosity, which promoted greater collection of biomass. From the results, it could be concluded that the reactors presented satisfactory performance, especially when using the foam as a support. Furthermore, the modified Stover-Kincannon and second order for multicomponent substrate degradation models were successfully used to develop a model of the experimental data.

  13. Mesophilic anaerobic co-digestion of poultry dropping and Carica papaya peels: Modelling and process parameter optimization study.

    PubMed

    Dahunsi, S O; Oranusi, S; Owolabi, J B; Efeovbokhan, V E

    2016-09-01

    The study evaluated anaerobic co-digestion of poultry dropping and pawpaw peels and the optimization of important process parameters. The physic-chemical analyses of the substrates were done using standard methods after application of mechanical, thermal and chemical pre-treatments methods. Gas chromatography analysis revealed the gas composition to be within the range of 66-68% methane and 18-23% carbon dioxide. The study equally revealed that combination of the different pre-treatment methods enhanced enormous biogas yield from the digestion. Optimization of the generated biogas data were carried out using the Response Surface Methodology and the Artificial Neural Networks. The coefficient of determination (R(2)) for RSM (0.9181) was lower compare to that of ANN (0.9828). This shows that ANN model gives higher accuracy than RSM model for the current. Further usage of Carica papaya peels for biogas generation is advocated. PMID:27285574

  14. Methane production improvement by modulation of solid phase immersion in dry batch anaerobic digestion process: Dynamic of methanogen populations.

    PubMed

    André, L; Ndiaye, M; Pernier, M; Lespinard, O; Pauss, A; Lamy, E; Ribeiro, T

    2016-05-01

    Several 60L dry batch anaerobic digestion (AD) reactors were implemented with or without liquid reserve on cattle manure. The immersed part modulation of cattle manure increased the methane flow of about 13%. The quantitative real time PCR and the optimized DNA extraction were implemented and validated to characterize and quantify the methanogen dynamic in dry batch AD process. Final quantities of methanogens converged toward the same level in several inocula at the end of AD. Methanogen dynamic was shown by dominance of Methanosarcinaceae for acetotrophic methanogens and Methanobacteriales for the hydrogenotrophic methanogens. Overall, methanogens populations were stabilized in liquid phase, except Methanosaetaceae. Solid phase was colonized by Methanomicrobiales and Methanosarcinaceae populations giving a support to biofilm development. The methane increase could be explained by a raise of Methanosarcinaceae population in presence of a total contact between solid and liquid phases. Methanosarcinaceae was a bio-indicator of the methane production. PMID:26897414

  15. Methane production improvement by modulation of solid phase immersion in dry batch anaerobic digestion process: Dynamic of methanogen populations.

    PubMed

    André, L; Ndiaye, M; Pernier, M; Lespinard, O; Pauss, A; Lamy, E; Ribeiro, T

    2016-05-01

    Several 60L dry batch anaerobic digestion (AD) reactors were implemented with or without liquid reserve on cattle manure. The immersed part modulation of cattle manure increased the methane flow of about 13%. The quantitative real time PCR and the optimized DNA extraction were implemented and validated to characterize and quantify the methanogen dynamic in dry batch AD process. Final quantities of methanogens converged toward the same level in several inocula at the end of AD. Methanogen dynamic was shown by dominance of Methanosarcinaceae for acetotrophic methanogens and Methanobacteriales for the hydrogenotrophic methanogens. Overall, methanogens populations were stabilized in liquid phase, except Methanosaetaceae. Solid phase was colonized by Methanomicrobiales and Methanosarcinaceae populations giving a support to biofilm development. The methane increase could be explained by a raise of Methanosarcinaceae population in presence of a total contact between solid and liquid phases. Methanosarcinaceae was a bio-indicator of the methane production.

  16. Effect of pretreatments on the semicontinuous anaerobic digestion of sunflower heads

    SciTech Connect

    Polat, H.; Selcuk, N.; Soyupak, S. )

    1992-10-01

    In this paper, the effects of hydraulic retention time and alkali treatment on methane production rate from the semicontinuous anaerobic digestion of 2% sunflower-head/water mixtures are investigated. The experiments were carried out in laboratory-scale fermenters, fed with 1 liter of untreated, 2 g of NaOH/100 g total solids (TS), and 5 g NaOH/100 g TS alkali-treated sunflower-head/water mixtures, respectively, and maintained at 55{degrees} C. Digestion experiments were performed for hydraulic retention times of 8, 10, and 15 days. The amount and composition of produced gas were measured until steady state was attained in each run. The steady-state methane production rates were found to decrease with hydraulic retention time and increase with alkali dosage used for pretreatment.

  17. Effect of gamma irradiation on the microstructure and post-mortem anaerobic metabolism of bovine muscle

    NASA Astrophysics Data System (ADS)

    Yook, Hong.-Sun; Lee, Ju.-Woon; Lee, Kyong.-Haeng; Kim, Moo.-Kang; Song, Chi.-won; Byun, Myung.-Woo

    2001-05-01

    Experiments were performed to study the effect of gamma irradiation on morphological properties and post-mortem metabolism in bovine M. sternomandibularis with special reference to ultrastructure, shear force, pH and ATP breakdown. The shortening of sarcomere was not observed in gamma-irradiated muscle, however, the disappearance of M-line and of A- and I-bands was perceptible. During cold storage, the destruction of muscle bundles was faster in the gamma-irradiated muscle than in the non-irradiated with a dose-dependent manner. The same is true for the post mortem pH drop and ATP breakdown. So, experimental results confirmed that the anaerobic metabolism and morphological properties are noticeably affected by gamma irradiation in beef.

  18. Enhancement of bioenergy production from organic wastes by two-stage anaerobic hydrogen and methane production process.

    PubMed

    Luo, Gang; Xie, Li; Zhou, Qi; Angelidaki, Irini

    2011-09-01

    The present study investigated a two-stage anaerobic hydrogen and methane process for increasing bioenergy production from organic wastes. A two-stage process with hydraulic retention time (HRT) 3d for hydrogen reactor and 12d for methane reactor, obtained 11% higher energy compared to a single-stage methanogenic process (HRT 15 d) under organic loading rate (OLR) 3 gVS/(L d). The two-stage process was still stable when the OLR was increased to 4.5 gVS/(Ld), while the single-stage process failed. The study further revealed that by changing the HRT(hydrogen):HRT(methane) ratio of the two-stage process from 3:12 to 1:14, 6.7%, more energy could be obtained. Microbial community analysis indicated that the dominant bacterial species were different in the hydrogen reactors (Thermoanaerobacterium thermosaccharolyticum-like species) and methane reactors (Clostridium thermocellum-like species). The changes of substrates and HRT did not change the dominant species. The archaeal community structures in methane reactors were similar both in single- and two- stage reactors, with acetoclastic methanogens Methanosarcina acetivorans-like organisms as the dominant species.

  19. Effects of Short Term Camp Periods on Aerobic and Anaerobic Performance Parameters in Ice Hockey National Team Athletes

    ERIC Educational Resources Information Center

    Eler, Serdar

    2016-01-01

    This study was conducted for determining the effects of trainings, applied to athletes during short term camp period, on their aerobic and anaerobic performance. Measurements were made by the participation of 28 volunteer male ice hockey national team players. During the 15-day camp period, 10-minute running and stretching for warming and then…

  20. Effect of anaerobic soil disinfestation and mustard seed meal for control of charcoal rot in California strawberries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic soil disinfestation (ASD) and mustard seed meal (MSM) appear to be promising non-fumigant alternatives for soilborne disease control. However studies of their effect on charcoal rot caused by Macrophomina phaseolina in California strawberry are limited. ASD with rice bran 20 t ha-1 (ASD-RB...

  1. Effect of nickel ions on anaerobic methane production from water hyacinth.

    PubMed

    Cai, Xuan; Hong, Zi-Jian; Dai, Rui-Hua; Liu, Yan; Liu, Xiang

    2012-01-01

    The effect of different concentrations of nickel ions (Ni(2+), 0, 10, 40 and 80 mg/L) on the anaerobic methane production of water hyacinth were investigated. Under these four concentrations, the methane production in 40 d was 2,275, 2,703, 3,210 and 2,481 mL, respectively. This situation illustrated that the Ni(2+) promoted the growth of hydrogen-producing acetic acid bacteria and methanogenic bacteria, even at high concentrations (i.e. 40-80 mg/L). The highest methane production per unit weight water hyacinth reached 206 mL/gTS with 40 mg/L Ni(2+). Meanwhile, the modified Gompertz and Logistic equations were applied to describe the effect on anaerobic culture of Ni(2+). According to these models, the values of methane production potential (mL) for four concentrations were in the following order: 40 mg/L (3,123.42 ± 60.08) > 10 mg/L (2,541.16 ± 46.94) > 80 mg/L (2,432.36 ± 40.18) > 0 mg/L (2,238.10 ± 31.90). According to the analysis of the digestate, the residual concentration of Ni(2+) was approximately 1.05-4.9 mg/L, which was relatively low compared with the Ni(2+) concentrations in the raw feedstock. The results would provide academic guidance and technical support for treatment of water hyacinth with an accumulation of heavy metals. PMID:22258675

  2. The effects of creatine loading and gender on anaerobic running capacity.

    PubMed

    Fukuda, David H; Smith, Abbie E; Kendall, Kristina L; Dwyer, Teddi R; Kerksick, Chad M; Beck, Travis W; Cramer, Joel T; Stout, Jeffrey R

    2010-07-01

    Creatine (Cr) loading consists of short-term, high-dosage Cr supplementation and has been shown to increase intramuscular total Cr content. Increases in body weight (BW) have been shown to result from Cr loading, with differences by gender, and increased BW may impact weight-bearing exercise. The critical velocity (CV) test is used to quantify the relationship between total running distance and time to exhaustion. The CV test provides the variable, anaerobic running capacity (ARC), which is an estimate of the anaerobic energy reserves in muscle. The purpose of this study was to examine the effects of gender and Cr loading on ARC. Fifty moderately trained men and women volunteered to participate in this randomized, double-blinded, placebo (PL)-controlled, repeated-measures study. After a familiarization session, a 3-day testing procedure was conducted. A maximal oxygen consumption test VO(2)max) on a treadmill was performed on day 1 to establish the maximum velocity (Vmax) at VO(2)max and to record BW. Days 2 and 3 involved treadmill running at varying percentages of Vmax. Participants were randomly assigned to either the Cr or PL group and received 20 packets of the Cr supplement (1 packet = 5 g Cr citrate, 18 g dextrose) or 20 packets of the PL (1 packet = 18 g dextrose). After consuming 4 packets daily for 5 consecutive days, the 3-day testing procedure was repeated. The male Cr loading group exhibited a 23% higher (p = 0.003) ARC compared to the PL group. Nonsignificant BW increases were found for the Cr groups. These findings suggest that Cr loading may be an effective strategy for improving ARC in men, but not in women, and revealed only nonsignificant increases in BW. Creatine loading may be used before competition by athletes to provide improvements in high-intensity, short-duration activities.

  3. Effect of nickel ions on anaerobic methane production from water hyacinth.

    PubMed

    Cai, Xuan; Hong, Zi-Jian; Dai, Rui-Hua; Liu, Yan; Liu, Xiang

    2012-01-01

    The effect of different concentrations of nickel ions (Ni(2+), 0, 10, 40 and 80 mg/L) on the anaerobic methane production of water hyacinth were investigated. Under these four concentrations, the methane production in 40 d was 2,275, 2,703, 3,210 and 2,481 mL, respectively. This situation illustrated that the Ni(2+) promoted the growth of hydrogen-producing acetic acid bacteria and methanogenic bacteria, even at high concentrations (i.e. 40-80 mg/L). The highest methane production per unit weight water hyacinth reached 206 mL/gTS with 40 mg/L Ni(2+). Meanwhile, the modified Gompertz and Logistic equations were applied to describe the effect on anaerobic culture of Ni(2+). According to these models, the values of methane production potential (mL) for four concentrations were in the following order: 40 mg/L (3,123.42 ± 60.08) > 10 mg/L (2,541.16 ± 46.94) > 80 mg/L (2,432.36 ± 40.18) > 0 mg/L (2,238.10 ± 31.90). According to the analysis of the digestate, the residual concentration of Ni(2+) was approximately 1.05-4.9 mg/L, which was relatively low compared with the Ni(2+) concentrations in the raw feedstock. The results would provide academic guidance and technical support for treatment of water hyacinth with an accumulation of heavy metals.

  4. Co-occurrence of nitrite-dependent anaerobic ammonium and methane oxidation processes in subtropical acidic forest soils.

    PubMed

    Meng, Han; Wang, Yong-Feng; Chan, Ho-Wang; Wu, Ruo-Nan; Gu, Ji-Dong

    2016-09-01

    Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two new processes of recent discoveries linking the microbial nitrogen and carbon cycles. In this study, 16S ribosomal RNA (rRNA) gene of anammox bacteria and pmoA gene of n-damo bacteria were used to investigate their distribution and diversity in natural acidic and re-vegetated forest soils. The 16S rRNA gene sequences retrieved featured at least three species in two genera known anammox bacteria, namely Candidatus Brocadia anammoxidans, Candidatus Brocadia fulgida, and Candidatus Kuenenia stuttgartiensis while the pmoA gene amplified was affiliated with two species of known n-damo bacteria Candidatus Methylomirabilis oxyfera and a newly established Candidatus Methylomirabilis sp. According to the results, the diversity of anammox bacteria in natural forests was lower than in re-vegetated forests, but no significant difference was observed in n-damo community between them. Quantitative real-time PCR showed that both anammox and n-damo bacteria were more abundant in the lower layer (10-20 cm) than the surface layer (0-5 cm). The abundance of anammox bacteria varied from 2.21 × 10(5) to 3.90 × 10(6) gene copies per gram dry soil, and n-damo bacteria quantities were between 1.69 × 10(5) and 5.07 × 10(6) gene copies per gram dry soil in the two different layers. Both anammox and n-damo bacteria are reported for the first time to co-occur in acidic forest soil in this study, providing a more comprehensive information on more defined microbial processes contributing to C and N cycles in the ecosystems. PMID:27178181

  5. Effect of sulfate on anaerobic degradation of benzoate in UASB reactors

    SciTech Connect

    Fang, H.H.P.; Liu, Y.; Chen, T.

    1997-04-01

    Anaerobic processes have been widely used for the treatment of various high-strength industrial wastewaters. However, application has been limited for the treatment of sulfate-rich industrial wastewaters, such as those from the petrochemical, and mining industries. Wastewaters containing benzoate and sulfate were treated in two upflow anaerobic sludge blanket (UASB) reactors at 34--37 C for 320 d. The sulfate concentration was increased stepwise in Reactor-A up to 7,500 mg/L, and was kept mostly constant at 3,000 mg/L in Reactor-B. Both reactors removed over 98% of organic chemical-oxygen demand (COD) for sulfate up to 6,000 mg/L, despite the fact that the mixed liquor contained up to 769 mg S/L of total sulfides and up to 234 mg S/L of dissolved H{sub 2}S. Sulfate0reducing efficiency decreased with the increase in sulfate concentration, but increased with time at each sulfate concentration. Reactor-B consistently reduced 89% of sulfate. However, both organic COD removal and sulfate-reducing efficiencies of Reactor-A dropped drastically at 7,500 mg SO{sub 4}{sup {minus}2}/L, and showed no sign of recovery after 50 d. The system failure was likely due to the increased sulfate, instead of sulfide, toxicity. From the COD balance, 93.4% of COD removed was converted to methane instead of sulfides, with a net sludge yield of 0.047 g volatile suspended solids (VSS)/g COD. The sulfur balance was over 97%.

  6. Effect of community structure on the kinetics of anaerobic degradation of aromatic compounds

    SciTech Connect

    McInerney, M.J.

    1989-11-01

    The kinetics of benzoate degradation by Syntrophus buswellii grown in coculture with Desulfovibrio strain G-11 was determined. At low benzoate concentrations the rate of degradation deviated from that predicted by a first-order decay process and reached a threshold of 2 to 3 {mu}M benzoate. S. buswellii was adapted to grow with crotonate and experiments are in progress to isolate this bacterium. An anaerobic bacterium was isolated that catalyzed the cleavage of an aryl ether bond of phenoxyacetate and its chlorinated derivatives forming the respective phenol. The anaerobic fatty acid-degrading bacterium, Syntrophomonas wolfei, catalyzed a rapid formate-bicarbonate exchange reaction and slowly degraded formate. Enzymatic studies showed that the levels of hydrogenase in cell-free extracts of S. wolfei grown in pure culture or in coculture with Methanospirillum hungatei contained very high specific activities of hydrogenase. Formate dehydrogenase activity was present, but the activity was 700 to 900-fold less than hydrogenase activity. S. wolfei was adapted to grow with mono and di-unsaturated fatty acids 5 to 6 carbons in length. Analysis of the fermentation products showed that part of the substrate was {beta}-oxidized while remainder was reduced to the corresponding saturated fatty acid. Propionate was produced from a hexadienoate suggesting that another pathway in addition to {beta}-oxidation exists for the degradation of this compound. Labeling studies and analysis of the monomeric composition of poly-{beta}-hydroxyalkanoate in S. wolfei showed that early in growth PHA was made by the incorporation of an intermediate without cleavage of a C-C bond. Later, PHA was made by a pathway in equilibrium with the acetate pool.

  7. Simultaneous removal of ammonia, P and COD from anaerobically digested piggery wastewater using an integrated process of chemical precipitation and air stripping.

    PubMed

    Quan, Xuejun; Ye, Changying; Xiong, Yanqi; Xiang, Jinxin; Wang, Fuping

    2010-06-15

    The paper presented an efficient integrated physicochemical process, which consists of chemical precipitation and air stripping, for the simultaneous removal of NH(3)-N, total P and COD from anaerobically digested piggery wastewater. In the integrated process, Ca(OH) (2) was used as the precipitant for NH(4)(+), PO(4)(3-) and organic phosphorous compounds, and as the pH adjuster for the air stripping of residual ammonia. The possibility of the suggested process and the related mechanisms were first investigated through a series of equilibrium tests. Laboratory scale tests were carried out to validate the application possibility of the integrated process using a new-patented water sparged aerocyclone reactor (WSA). The WSA could be effectively used for the simultaneous removal of NH(3)-N, total P and COD. 3g/L of Ca(OH) (2) is a proper dosage for the simultaneous removal. The simultaneous removal of NH(3)-N, total P and COD in the WSA reactor could be easily optimized by selecting a proper air inlet velocity and a proper jet velocity of the liquid phase. In all the cases, the removal efficiencies of the NH(3)-N, total P and COD were over 91%, 99.2% and 52% for NH(3)-N, total P and COD, respectively. The formed precipitates in the process could be easily settled down from the suspension system. Therefore, the integrated process provided an efficient alternative for the simultaneous removal of NH(3)-N, total P and COD from the wastewater.

  8. Lifecycle Greenhouse Gas Analysis of an Anaerobic Codigestion Facility Processing Dairy Manure and Industrial Food Waste.

    PubMed

    Ebner, Jacqueline H; Labatut, Rodrigo A; Rankin, Matthew J; Pronto, Jennifer L; Gooch, Curt A; Williamson, Anahita A; Trabold, Thomas A

    2015-09-15

    Anaerobic codigestion (AcoD) can address food waste disposal and manure management issues while delivering clean, renewable energy. Quantifying greenhouse gas (GHG) emissions due to implementation of AcoD is important to achieve this goal. A lifecycle analysis was performed on the basis of data from an on-farm AcoD in New York, resulting in a 71% reduction in GHG, or net reduction of 37.5 kg CO2e/t influent relative to conventional treatment of manure and food waste. Displacement of grid electricity provided the largest reduction, followed by avoidance of alternative food waste disposal options and reduced impacts associated with storage of digestate vs undigested manure. These reductions offset digester emissions and the net increase in emissions associated with land application in the AcoD case relative to the reference case. Sensitivity analysis showed that using feedstock diverted from high impact disposal pathways, control of digester emissions, and managing digestate storage emissions were opportunities to improve the AcoD GHG benefits. Regional and parametrized emissions factors for the storage emissions and land application phases would reduce uncertainty. PMID:26241377

  9. Kinetic modelling of anaerobic hydrolysis of solid wastes, including disintegration processes

    SciTech Connect

    García-Gen, Santiago; Sousbie, Philippe; Rangaraj, Ganesh; Lema, Juan M.; Rodríguez, Jorge; Steyer, Jean-Philippe; Torrijos, Michel

    2015-01-15

    Highlights: • Fractionation of solid wastes into readily and slowly biodegradable fractions. • Kinetic coefficients estimation from mono-digestion batch assays. • Validation of kinetic coefficients with a co-digestion continuous experiment. • Simulation of batch and continuous experiments with an ADM1-based model. - Abstract: A methodology to estimate disintegration and hydrolysis kinetic parameters of solid wastes and validate an ADM1-based anaerobic co-digestion model is presented. Kinetic parameters of the model were calibrated from batch reactor experiments treating individually fruit and vegetable wastes (among other residues) following a new protocol for batch tests. In addition, decoupled disintegration kinetics for readily and slowly biodegradable fractions of solid wastes was considered. Calibrated parameters from batch assays of individual substrates were used to validate the model for a semi-continuous co-digestion operation treating simultaneously 5 fruit and vegetable wastes. The semi-continuous experiment was carried out in a lab-scale CSTR reactor for 15 weeks at organic loading rate ranging between 2.0 and 4.7 g VS/L d. The model (built in Matlab/Simulink) fit to a large extent the experimental results in both batch and semi-continuous mode and served as a powerful tool to simulate the digestion or co-digestion of solid wastes.

  10. Meta-analysis of greenhouse gas emissions from anaerobic digestion processes in dairy farms.

    PubMed

    Miranda, Nicole D; Tuomisto, Hanna L; McCulloch, Malcolm D

    2015-04-21

    This meta-analysis quantifies the changes in greenhouse gas (GHG) emissions from dairy farms, caused by anaerobically digesting (AD) cattle manure. As this is a novel quantifiable synthesis of the literature, a database of GHG emissions from dairy farms is created. Each case in the database consists of a baseline (reference with no AD system) and an AD scenario. To enable interstudy comparison, emissions are normalized by calculating relative changes (RCs). The distributions of RCs are reported by specific GHGs and operation units. Nonparametric tests are applied to the RCs in order to identify a statistical difference of AD with respect to baseline scenarios (Wilcoxon rank test), correlations (Spearman test), and best estimation for changes in emissions (Kernel density distribution estimator). From 749 studies identified, 30 papers yield 89 independent cases. The median reductions in emissions from the baseline scenarios, according to operation units, are -43.2% (n.s.) for storage, -6.3% for field application of slurries, -11.0% for offset of energy from fossil fuel, and +0.4% (n.s.) for offset of inorganic fertilizers. The leaks from digesters are found to significantly increase the emissions from baseline scenarios (median = +1.4%). PMID:25790272

  11. Lifecycle Greenhouse Gas Analysis of an Anaerobic Codigestion Facility Processing Dairy Manure and Industrial Food Waste.

    PubMed

    Ebner, Jacqueline H; Labatut, Rodrigo A; Rankin, Matthew J; Pronto, Jennifer L; Gooch, Curt A; Williamson, Anahita A; Trabold, Thomas A

    2015-09-15

    Anaerobic codigestion (AcoD) can address food waste disposal and manure management issues while delivering clean, renewable energy. Quantifying greenhouse gas (GHG) emissions due to implementation of AcoD is important to achieve this goal. A lifecycle analysis was performed on the basis of data from an on-farm AcoD in New York, resulting in a 71% reduction in GHG, or net reduction of 37.5 kg CO2e/t influent relative to conventional treatment of manure and food waste. Displacement of grid electricity provided the largest reduction, followed by avoidance of alternative food waste disposal options and reduced impacts associated with storage of digestate vs undigested manure. These reductions offset digester emissions and the net increase in emissions associated with land application in the AcoD case relative to the reference case. Sensitivity analysis showed that using feedstock diverted from high impact disposal pathways, control of digester emissions, and managing digestate storage emissions were opportunities to improve the AcoD GHG benefits. Regional and parametrized emissions factors for the storage emissions and land application phases would reduce uncertainty.

  12. Utilization of biogas produced by anaerobic digestion of agro-industrial waste: Energy, economic and environmental effects.

    PubMed

    Hublin, Andrea; Schneider, Daniel Rolph; Džodan, Janko

    2014-07-01

    Anaerobic digestion of agro-industrial waste is of significant interest in order to facilitate a sustainable development of energy supply. Using of material and energy potentials of agro-industrial waste, in the framework of technical, economic, and ecological possibilities, contributes in increasing the share of energy generated from renewable energy sources. The paper deals with the benefits arising from the utilization of biogas produced by co-digestion of whey and cow manure. The advantages of this process are the profitability of the plant and the convenience in realizing an anaerobic digestion plant to produce biogas that is enabled by the benefits from the sale of electric energy at favorable prices. Economic aspects are related to the capital cost (€ 2,250,000) of anaerobic digestion treatment in a biogas plant with a 300 kW power and 510 kW heating unit in a medium size farm (450 livestock units). Considering the optimum biogas yield of 20.7 dm(3) kg(-1) of wet substrate and methane content in the biogas obtained of 79%, the anaerobic process results in a daily methane production of 2,500 kg, with the maximum power generation of 2,160,000 kWh y(-1) and heat generation of 2,400,000 kWh y(-1) The net present value (NPV), internal rate of return (IRR) and payback period for implementation of profitable anaerobic digestion process is evaluated. Ecological aspects related to carbon dioxide (CO2) and methane (CH4) emission reduction are assessed.

  13. Calculation of energy recovery and greenhouse gas emission reduction from palm oil mill effluent treatment by an anaerobic granular-sludge process.

    PubMed

    Show, K Y; Ng, C A; Faiza, A R; Wong, L P; Wong, L Y

    2011-01-01

    Conventional aerobic and low-rate anaerobic processes such as pond and open-tank systems have been widely used in wastewater treatment. In order to improve treatment efficacy and to avoid greenhouse gas emissions, conventional treatment can be upgraded to a high performance anaerobic granular-sludge system. The anaerobic granular-sludge systems are designed to capture the biogas produced, rendering a potential for claims of carbon credits under the Kyoto Protocol for reducing emissions of greenhouse gases. Certified Emission Reductions (CERs) would be issued, which can be exchanged between businesses or bought and sold in international markets at the prevailing market prices. As the advanced anaerobic granular systems are capable of handling high organic loadings concomitant with high strength wastewater and short hydraulic retention time, they render more carbon credits than other conventional anaerobic systems. In addition to efficient waste degradation, the carbon credits can be used to generate revenue and to finance the project. This paper presents a scenario on emission avoidance based on a methane recovery and utilization project. An example analysis on emission reduction and an overview of the global emission market are also outlined. PMID:22170839

  14. Calculation of energy recovery and greenhouse gas emission reduction from palm oil mill effluent treatment by an anaerobic granular-sludge process.

    PubMed

    Show, K Y; Ng, C A; Faiza, A R; Wong, L P; Wong, L Y

    2011-01-01

    Conventional aerobic and low-rate anaerobic processes such as pond and open-tank systems have been widely used in wastewater treatment. In order to improve treatment efficacy and to avoid greenhouse gas emissions, conventional treatment can be upgraded to a high performance anaerobic granular-sludge system. The anaerobic granular-sludge systems are designed to capture the biogas produced, rendering a potential for claims of carbon credits under the Kyoto Protocol for reducing emissions of greenhouse gases. Certified Emission Reductions (CERs) would be issued, which can be exchanged between businesses or bought and sold in international markets at the prevailing market prices. As the advanced anaerobic granular systems are capable of handling high organic loadings concomitant with high strength wastewater and short hydraulic retention time, they render more carbon credits than other conventional anaerobic systems. In addition to efficient waste degradation, the carbon credits can be used to generate revenue and to finance the project. This paper presents a scenario on emission avoidance based on a methane recovery and utilization project. An example analysis on emission reduction and an overview of the global emission market are also outlined.

  15. Post-treatment of anaerobically degraded azo dye Acid Red 18 using aerobic moving bed biofilm process: enhanced removal of aromatic amines.

    PubMed

    Koupaie, E Hosseini; Moghaddam, M R Alavi; Hashemi, S H

    2011-11-15

    The application of aerobic moving bed biofilm process as post-treatment of anaerobically degraded azo dye Acid Red 18 was investigated in this study. The main objective of this work was to enhance removal of anaerobically formed the dye aromatic metabolites. Three separate sequential treatment systems were operated with different initial dye concentrations of 100, 500 and 1000 mg/L. Each treatment system consisted of an anaerobic sequencing batch reactor (An-SBR) followed by an aerobic moving bed sequencing batch biofilm reactor (MB-SBBR). Up to 98% of the dye decolorization and more than 80% of the COD removal occurred anaerobically. The obtained results suggested no significant difference in COD removal as well as the dye decolorization efficiency using three An-SBRs receiving different initial dye concentrations. Monitoring the dye metabolites through HPLC suggested that more than 80% of anaerobically formed 1-naphthylamine-4-sulfonate was completely removed in the aerobic biofilm reactors. Based on COD analysis results, at least 65-72% of the dye total metabolites were mineralized during the applied treatment systems. According to the measured biofilm mass and also based on respiration-inhibition test results, increasing the initial dye concentration inhibited the growth and final mass of the attached-growth biofilm in MB-SBBRs.

  16. Inhibitory effect of high NH4(+)-N concentration on anaerobic biotreatment of fresh leachate from a municipal solid waste incineration plant.

    PubMed

    Liu, Zhao; Dang, Yan; Li, Caihua; Sun, Dezhi

    2015-09-01

    Fresh leachate from municipal solid waste (MSW) incineration plants generally contains extremely high NH4(+)-N concentration which could inhibit the bioactivity of microorganisms. The inhibitory effect of high NH4(+)-N concentration on anaerobic biotreatment of fresh leachate from a MSW incineration plant in China has been investigated in this study. The inhibition processes was studied by both static tests and a laboratory-scale expanded granular sludge bed (EGSB) reactor. The specific methanogenic activity (SMA) of the microorganisms in anaerobic granular sludge was inhibited with the NH4(+)-N concentration increasing to 1000mg/L in static tests. As well the chemical oxygen demand (COD) removal efficiency and the methane yield decreased in the EGSB reactor, while the volatile fatty acids (VFAs) accumulated and extracellular polymeric substances (EPS) of the anaerobic granular sludge increased with NH4(+)-N concentration rising to 1000mg/L, without any rebounding during 30days of operation. Decreasing NH4(+)-N concentration to 500mg/L in influent, the COD removal efficiency recovered to about 85% after 26days. 1000mg/L of NH4(+)-N in leachate was suggested to be the inhibition threshold in EGSB reactor. High-throughput sequencing results showed little changes in microbial communities of the sludge for a high NH4(+)-N concentration, indicating that the survival of most microorganisms was not affected under such a condition. It inhibited the bioactivity of the microorganisms, resulting in decrease of the COD removal efficiency.

  17. Potentials for food waste minimization and effects on potential biogas production through anaerobic digestion.

    PubMed

    Schott, Anna Bernstad Saraiva; Vukicevic, Sanita; Bohn, Irene; Andersson, Tova

    2013-08-01

    Several treatment alternatives for food waste can result in both energy and nutrient recovery, and thereby potential environmental benefits. However, according to the European Union waste management hierarchy, waste prevention should be the prioritized strategy to decrease the environmental burdens from all solid waste management. The aim of the present study was therefore to investigate the potential for food waste minimization among Swedish households through an investigation of the amount of avoidable food waste currently disposed of. A further aim was to investigate the effect on the national biogas production potential through anaerobic digestion of food waste, considering minimization potentials. A method for waste composition analyses of household food waste, where a differentiation between avoidable and unavoidable food waste is made, was used in a total of 24 waste composition analyses of household waste from Swedish residential areas. The total household food waste generation reached 3.4 kg (household and week)(-1), on average, of which 34% is avoidable. The theoretical methane (CH4) potential in unavoidable food waste reached 442 Ndm(3) (kg VS)(-1) or 128 Nm(3) tonne(-1) wet waste, while the measured (mesophilic CH4 batch tests) CH4 production reached 399 Ndm(3) (kg VS)(-1), which is lower than several previous assessments of CH4 production from household food waste. According to this study the combination of a decrease in food waste generation-in case of successful minimization-and decreased CH4 production from unavoidable food waste will thus result in lower total potential energy recovery from household food waste through anaerobic digestion CH4 potential than previously stated.

  18. Effects of reactor configuration on the performance of static-bed submerged media anaerobic reactors

    SciTech Connect

    Chiang, C.F.

    1988-01-01

    Three different configurations of cylindrical submerged media anaerobic reactors (SMARs) with packing volumes of 85 items were operated at 35 C for 415 days with COD loading rates varying from 1 to 12 g/l/d and three retention times of 0.5, 1, and 2 days. A synthetic waste consisting of a milk solution with a mineral supplement was used for the feed. Tracer studies on clean-bed and dirty-bed SMARs indicate that reactor configuration, biogas mixing, and biomass accumulation all have a significant effect on SMAR hydraulics and cause short-circuiting. Based on the isothermal energy dissipation theory, the higher hydrostatic pressures resulting from higher SMAR heights increases self-induced biogas mixing and improves the contact efficiency between substrate and organisms. Based on TCOD removal rate, the tallest SMAR performed slightly better at COD loading rates above 4/g/l/d. At COD loading rates equal to or below 4 g/l/d, there was little difference in TCOD removal rate between the three SMARs. The acetoclastic methanogenic activity (AMA) test developed in this study is reproducible with 6.5% at a mean of 0.39 l CH{sub 4} (STP)/gm VSS/d. For VSS less than 1 g/l, a higher AMA is associated with lower VSS concentrations. For VSS greater than 1 g/l, AMA varies within a narrow range of 0.1 to 0.2 l CH{sub 4} (STP)/gm VSS/d. Exit gas recycle at a ratio of 3.5-7.0% of exit gas flowrate resulted in a 5-13% increase in the methane content of the exit gas at a COD loading rate of about 10 g/l/d and a detention time of about 2 days. This suggest that, at high loading rates, hydrogen dissolution rate may be the rate-limiting step in anaerobic digestion.

  19. Acute Effects of Peristaltic Pneumatic Compression on Repeated Anaerobic Exercise Performance and Blood Lactate Clearance.

    PubMed

    Martin, Jeffrey S; Friedenreich, Zachary D; Borges, Alexandra R; Roberts, Michael D

    2015-10-01

    External pneumatic compression (EPC) use in athletics is increasing. However, there is a paucity of evidence supporting the effectiveness of EPC in aiding recovery and performance. We sought to determine the efficacy of EPC for acute recovery of anaerobic power and lactate clearance following a fatigue protocol. Fourteen (n = 14; women = 7 and men = 7), apparently healthy, active subjects (aged 22.73 ± 4.05 years) were enrolled in this randomized crossover design study. After familiarization sessions, subjects completed 2 study trials separated by 3-7 days. Trials consisted of a fatigue protocol (two 30-second Wingate anaerobic tests (WAnTs) on a cycle ergometer separated by 3 minutes of rest), 30 minutes of treatment with EPC or sham, and, finally, a single 30-second WAnT. A peristaltic pulse EPC device was used with target inflation pressures of ∼70 mm Hg applied to the lower limbs. Peak power (PkP), average power (AP), and the fatigue index (FI) were recorded for each WAnT. Moreover, blood lactate concentration (BLa) was evaluated at baseline and at regular intervals during recovery (5, 15, 25, and 35 minutes postfatigue protocol). No significant differences in PkP, AP, and FI were observed. However, BLa was significantly lower at 25 and 35 minutes of recovery (8.91 ± 3.12 vs. 10.66 ± 3.44 mmol·L(-1) [p = 0.021] and 6.44 ± 2.14 vs. 7.89 ± 2.37 mmol·L(-1) [p = 0.006] for EPC vs. sham, respectively). Application of EPC during recovery may be a viable alternative when "inactive" recovery is desirable.

  20. Archaeal community dynamics and abiotic characteristics in a mesophilic anaerobic co-digestion process treating fruit and vegetable processing waste sludge with chopped fresh artichoke waste.

    PubMed

    Ros, M; Franke-Whittle, I H; Morales, A B; Insam, H; Ayuso, M; Pascual, J A

    2013-05-01

    This study evaluated the feasibility of obtaining methane in anaerobic digestion (AD) from the waste products generated by the processing of fruit and vegetables. During the first phase (0-55 d) of the AD using sludge from fruit and vegetable processing, an average value of 244±88 L kg(-1) dry matter d(-1)of biogas production was obtained, and methane content reached 65% of the biogas. Co-digestion with chopped fresh artichoke wastes in a second phase (55-71 d) enhanced biogas production, and resulted in an average value of 354±68 L kg(-1) dry matter d(-1), with higher methane content (more than 70%). The archaeal community involved in methane production was studied using the ANAEROCHIP microarray and real-time PCR. Results indicated that species of Methanosaeta and Methanosarcina were important during the AD process. Methanosarcina numbers increased after the addition of chopped fresh artichoke, while Methanosaeta numbers decreased. PMID:23548398

  1. Effect of seasonal changes in quantities of biowaste on full scale anaerobic digester performance

    SciTech Connect

    Illmer, P. Gstraunthaler, G.

    2009-01-15

    A 750,000 l digester located in Roppen/Austria was studied over a 2-year period. The concentrations and amounts of CH{sub 4}, H{sub 2}, CO{sub 2} and H{sub 2}S and several other process parameters like temperature, retention time, dry weight and input of substrate were registered continuously. On a weekly scale the pH and the concentrations of NH{sub 4}{sup +}-N and volatile fatty acids (acetic, butyric, iso-butyric, propionic, valeric and iso-valeric acid) were measured. The data show a similar pattern of seasonal gas production over 2 years of monitoring. The consumption of VFA and not the hydrogenotrophic CH{sub 4} production appeared to be the limiting factor for the investigated digestion process. Whereas the changes in pH and the concentrations of most VFA did not correspond with changes in biogas production, the ratio of acetic to propionic acid and the concentration of H{sub 2} appeared to be useful indicators for reactor performance. However, the most influential factors for the anaerobic digestion process were the amount and the quality of input material, which distinctly changed throughout the year.

  2. A case study of coupling upflow anaerobic sludge blanket (UASB) and ANITA™ Mox process to treat high-strength landfill leachate.

    PubMed

    Lu, Ting; George, Biju; Zhao, Hong; Liu, Wenjun

    2016-01-01

    A pilot study was conducted to study the treatability of high-strength landfill leachate by a combined process including upflow anaerobic sludge blanket (UASB), carbon removal (C-stage) moving bed biofilm reactor (MBBR) and ANITA™ Mox process. The major innovation on this pilot study is the patent-pending process invented by Veolia that integrates the above three unit processes with an effluent recycle stream, which not only maintains the low hydraulic retention time to enhance the treatment performance but also reduces inhibiting effect from chemicals present in the high-strength leachate. This pilot study has demonstrated that the combined process was capable of treating high-strength leachate with efficient chemical oxygen demand (COD) and nitrogen removals. The COD removal efficiency by the UASB was 93% (from 45,000 to 3,000 mg/L) at a loading rate of 10 kg/(m(3)·d). The C-stage MBBR removed an additional 500 to 1,000 mg/L of COD at a surface removal rate (SRR) of 5 g/(m(2)·d) and precipitated 400 mg/L of calcium. The total inorganic nitrogen removal efficiency by the ANITA Mox reactor was about 70% at SRR of 1.0 g/(m(2)·d). PMID:26877051

  3. A case study of coupling upflow anaerobic sludge blanket (UASB) and ANITA™ Mox process to treat high-strength landfill leachate.

    PubMed

    Lu, Ting; George, Biju; Zhao, Hong; Liu, Wenjun

    2016-01-01

    A pilot study was conducted to study the treatability of high-strength landfill leachate by a combined process including upflow anaerobic sludge blanket (UASB), carbon removal (C-stage) moving bed biofilm reactor (MBBR) and ANITA™ Mox process. The major innovation on this pilot study is the patent-pending process invented by Veolia that integrates the above three unit processes with an effluent recycle stream, which not only maintains the low hydraulic retention time to enhance the treatment performance but also reduces inhibiting effect from chemicals present in the high-strength leachate. This pilot study has demonstrated that the combined process was capable of treating high-strength leachate with efficient chemical oxygen demand (COD) and nitrogen removals. The COD removal efficiency by the UASB was 93% (from 45,000 to 3,000 mg/L) at a loading rate of 10 kg/(m(3)·d). The C-stage MBBR removed an additional 500 to 1,000 mg/L of COD at a surface removal rate (SRR) of 5 g/(m(2)·d) and precipitated 400 mg/L of calcium. The total inorganic nitrogen removal efficiency by the ANITA Mox reactor was about 70% at SRR of 1.0 g/(m(2)·d).

  4. Effects of phosphate addition on methane fermentation in the batch and upflow anaerobic sludge blanket (UASB) reactors.

    PubMed

    Suzuki, Sho; Shintani, Masaki; Sanchez, Zoe Kuizon; Kimura, Kohei; Numata, Mitsuru; Yamazoe, Atsushi; Kimbara, Kazuhide

    2015-12-01

    Ammonia inhibition of methane fermentation is one of the leading causes of failure of anaerobic digestion reactors. In a batch anaerobic digestion reactor with 429 mM NH3-N/L of ammonia, the addition of 25 mM phosphate resulted in an increase in methane production rate. Similar results were obtained with the addition of disodium phosphate in continuous anaerobic digestion using an upflow anaerobic sludge blanket (UASB) reactor. While methane content and production rate decreased in the presence of more than 143 mM NH3-N/L of ammonium chloride in UASB, the addition of 5 mM disodium phosphate suppressed ammonia inhibition at 214 mM NH3-N/L of ammonium chloride. The addition prevented acetate/propionate accumulation, which might be one of the effects of the phosphate on the ammonia inhibition. The effects on the microbial community in the UASB reactor was also assessed, which was composed of Bacteria involved in hydrolysis, acidogenesis, acetogenesis, and dehydrogenation, as well as Archaea carrying out methanogenesis. The change in the microbial community was observed by ammonia inhibition and the addition of phosphate. The change indicates that the suppression of ammonia inhibition by disodium phosphate addition could stimulate the activity of methanogens, reduce shift in bacterial community, and enhance hydrogen-producing bacteria. The addition of phosphate will be an important treatment for future studies of methane fermentation.

  5. Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

    2016-05-01

    Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

  6. Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge

    PubMed Central

    Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

    2016-01-01

    Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them. PMID:27166174

  7. Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge.

    PubMed

    Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

    2016-05-11

    Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

  8. The effect of shock loading on the performance of a thermophilic anaerobic contact reactor at constant organic loading rate

    PubMed Central

    2014-01-01

    The influences of organic loading disturbances on the process performance of a thermophilic anaerobic contact reactor treating potato-processing wastewater were investigated. For this purpose, while the reactor was operated at steady state conditions with organic loading rate of 5.5 kg COD/m3 · day, an instant acetate concentration increase (1 g/L) was introduced to the reactor. During the shock loading test of acetate, it was observed that the overall process performance was adversely affected by all the shock loading, however, the system reached steady state conditions less than 24 hours of operation indicating that thermophilic anaerobic contact reactor is resistant to shock loading and be capable of returning its normal conditions within a short time period. PMID:24872886

  9. Effects of organic loading rate and effluent recirculation on the performance of two-stage anaerobic digestion of vegetable waste.

    PubMed

    Zuo, Zhuang; Wu, Shubiao; Zhang, Wanqin; Dong, Renjie

    2013-10-01

    The effects of organic loading rates (OLR) and effluent recirculation on dynamics of acidogenic and methanogenic processes in two-stage anaerobic digestion of vegetable waste were investigated. Two systems were performed at OLRs of 1.3, 1.7, 2.1 and 2.6 g VS/L/d. One system recirculated the effluent from the methanogenic reactor to acidogenic reactor. With increasing OLRs, total volatile fatty acid (VFA) concentration increased to approximately 8500 mg/L in acidogenic digester, where pH decreased from 6.4 to 5.2. Daily biogas production and methane content in methanogenic reactor increased from 1.2 to 4.4 L/d and from 27.4% to 60.5%, respectively. However, inhibition of hydrolysis in acidogenic reactor was demonstrated under the OLR of 2.6 g VS/L/d without recirculation, thus indicating system overloading. Effluent recirculation shown a considerable positive effect on alleviating VFA inhibition and improving biogas production in acidogenic reactor because of the effect of dilution and pH adjustment, particularly at high OLRs.

  10. Comparing mesophilic and thermophilic anaerobic digestion of chicken manure: Microbial community dynamics and process resilience

    SciTech Connect

    Niu, Qigui; Takemura, Yasuyuki; Kubota, Kengo; Li, Yu-You

    2015-09-15

    Highlights: • Microbial community dynamics and process functional resilience were investigated. • The threshold of TAN in mesophilic reactor was higher than the thermophilic reactor. • The recoverable archaeal community dynamic sustained the process resilience. • Methanosarcina was more sensitive than Methanoculleus on ammonia inhibition. • TAN and FA effects the dynamic of hydrolytic and acidogenic bacteria obviously. - Abstract: While methane fermentation is considered as the most successful bioenergy treatment for chicken manure, the relationship between operational performance and the dynamic transition of archaeal and bacterial communities remains poorly understood. Two continuous stirred-tank reactors were investigated under thermophilic and mesophilic conditions feeding with 10%TS. The tolerance of thermophilic reactor on total ammonia nitrogen (TAN) was found to be 8000 mg/L with free ammonia (FA) 2000 mg/L compared to 16,000 mg/L (FA1500 mg/L) of mesophilic reactor. Biomethane production was 0.29 L/gV S{sub in} in the steady stage and decreased following TAN increase. After serious inhibition, the mesophilic reactor was recovered successfully by dilution and washing stratagem compared to the unrecoverable of thermophilic reactor. The relationship between the microbial community structure, the bioreactor performance and inhibitors such as TAN, FA, and volatile fatty acid was evaluated by canonical correspondence analysis. The performance of methanogenic activity and substrate removal efficiency were changed significantly correlating with the community evenness and phylogenetic structure. The resilient archaeal community was found even after serious inhibition in both reactors. Obvious dynamics of bacterial communities were observed in acidogenic and hydrolytic functional bacteria following TAN variation in the different stages.

  11. High rate CNP removal from a milk processing wastewater in a single ultrasound augmented up-flow anaerobic/aerobic/anoxic bioreactor.

    PubMed

    Rezaee, S; Zinatizadeh, A A L; Asadi, A

    2015-03-01

    Simultaneous removal of carbon, nitrogen and phosphorus (CNP) in a single bioreactor is of high significance in terms of reactor volume and energy consumption. Therefore, in this study, an innovative up-flow anaerobic/aerobic/anoxic bioreactor (UAAASB) augmented by ultrasound was developed as a high rate single bioreactor for the simultaneous removal of nutrients from a milk processing wastewater. The ultrasonic irradiation used in this work was in the range of high frequency (1.7 MHz). The central composite design (CCD) and response surface methodology (RSM) were applied to design the experimental conditions, model obtained data, and optimize the process. The effects of three independent variables, i.e. hydraulic retention time (HRT), aeration mode and mixed liquor suspended solid (MLSS) concentration on 10 process responses were investigated. The results prove that the ultrasonic irradiation has a positive effect on the sludge settling velocity and effluent turbidity. The optimum conditions were determined as 12-15 h, 4000-5000 mg/l and 1.5-2 for HRT, MLSS concentration and aeration mode, respectively, based on removal efficiency of sCOD ⩾ 90%, TN and TP ⩾ 50%. PMID:25457518

  12. High rate CNP removal from a milk processing wastewater in a single ultrasound augmented up-flow anaerobic/aerobic/anoxic bioreactor.

    PubMed

    Rezaee, S; Zinatizadeh, A A L; Asadi, A

    2015-03-01

    Simultaneous removal of carbon, nitrogen and phosphorus (CNP) in a single bioreactor is of high significance in terms of reactor volume and energy consumption. Therefore, in this study, an innovative up-flow anaerobic/aerobic/anoxic bioreactor (UAAASB) augmented by ultrasound was developed as a high rate single bioreactor for the simultaneous removal of nutrients from a milk processing wastewater. The ultrasonic irradiation used in this work was in the range of high frequency (1.7 MHz). The central composite design (CCD) and response surface methodology (RSM) were applied to design the experimental conditions, model obtained data, and optimize the process. The effects of three independent variables, i.e. hydraulic retention time (HRT), aeration mode and mixed liquor suspended solid (MLSS) concentration on 10 process responses were investigated. The results prove that the ultrasonic irradiation has a positive effect on the sludge settling velocity and effluent turbidity. The optimum conditions were determined as 12-15 h, 4000-5000 mg/l and 1.5-2 for HRT, MLSS concentration and aeration mode, respectively, based on removal efficiency of sCOD ⩾ 90%, TN and TP ⩾ 50%.

  13. Methane production from rice straw with acclimated anaerobic sludge: effect of phosphate supplementation.

    PubMed

    Lei, Zhongfang; Chen, Jiayi; Zhang, Zhenya; Sugiura, Norio

    2010-06-01

    Rice straw particles were directly used as substrate for anaerobic digestion with acclimated sludge under room temperature and different levels of phosphate. Two obvious biogas production peaks were observed for all reactors, with biogas or methane yields of (0.33-0.35)m(3)/kg-VS loaded or (0.27-0.29)m(3) CH(4)/kg-VS loaded and average methane contents of 75.9-78.2%. A separated two-stage first-order kinetic model was developed in this study and showed a good fit to the experimental data when this complicated process was divided into two stages. The average biogas and methane production rate constants were (0.027-0.031)d(-1) and (0.028-0.033)d(-1), respectively, increased by 2-3 times in the second stages than those in the first. The results indicated that an adequate level of phosphate addition (465 mg-P/L) could accelerate the biogasification process: 7-13 days earlier appearance of the two peaks and shorter time needed for complete biogasification of rice straw.

  14. Enhancement of Bacterial Transport in Aerobic and Anaerobic Environments: Assessing the Effect of Metal Oxide Chemical Heterogeneities

    SciTech Connect

    T.C. Onstott

    2005-09-30

    The goal of our research was to understand the fundamental processes that control microbial transport in physically and chemically heterogeneous aquifers and from this enhanced understanding determine the requirements for successful, field-scale delivery of microorganisms to metal contaminated subsurface sites. Our specific research goals were to determine; (1) the circumstances under which the preferential adsorption of bacteria to Fe, Mn, and Al oxyhydroxides influences field-scale bacterial transport, (2) the extent to which the adhesion properties of bacterial cells affect field-scale bacterial transport, (3) whether microbial Fe(III) reduction can enhance field-scale transport of Fe reducing bacteria (IRB) and other microorganisms and (4) the effect of field-scale physical and chemical heterogeneity on all three processes. Some of the spin-offs from this basic research that can improve biostimulation and bioaugmentation remediation efforts at contaminated DOE sites have included; (1) new bacterial tracking tools for viable bacteria; (2) an integrated protocol which combines subsurface characterization, laboratory-scale experimentation, and scale-up techniques to accurately predict field-scale bacterial transport; and (3) innovative and inexpensive field equipment and methods that can be employed to enhance Fe(III) reduction and microbial transport and to target microbial deposition under both aerobic and anaerobic conditions.

  15. Effect of creatine on aerobic and anaerobic metabolism in skeletal muscle in swimmers.

    PubMed Central

    Thompson, C H; Kemp, G J; Sanderson, A L; Dixon, R M; Styles, P; Taylor, D J; Radda, G K

    1996-01-01

    OBJECTIVE: To examine the effect of a relatively low dose of creatine on skeletal muscle metabolism and oxygen supply in a group of training athletes. METHODS: 31P magnetic resonance and near-infrared spectroscopy were used to study calf muscle metabolism in a group of 10 female members of a university swimming team. Studies were performed before and after a six week period of training during which they took either 2 g creatine daily or placebo. Calf muscle metabolism and creatine/choline ratios were studied in resting muscle, during plantar flexion exercise (10-15 min), and during recovery from exercise. RESULTS: There was no effect of creatine on metabolite ratios at rest or on metabolism during exercise and recovery from exercise. Muscle oxygen supply and exercise performance were not improved by creatine if compared to placebo treated subjects. CONCLUSIONS: Oral creatine supplementation at 2 g daily has no effect on muscle creatine concentration, muscle oxygen supply or muscle aerobic or anaerobic metabolism during endurance exercise. PMID:8889115

  16. [Anaerobic digestion of lignocellulosic biomass with animal digestion mechanisms].

    PubMed

    Wu, Hao; Zhang, Pan-Yue; Guo, Jian-Bin; Wu, Yong-Jie

    2013-02-01

    Lignocellulosic material is the most abundant renewable resource in the earth. Herbivores and wood-eating insects are highly effective in the digestion of plant cellulose, while anaerobic digestion process simulating animal alimentary tract still remains inefficient. The digestion mechanisms of herbivores and wood-eating insects and the development of anaerobic digestion processes of lignocellulose were reviewed for better understanding of animal digestion mechanisms and their application in design and operation of the anaerobic digestion reactor. Highly effective digestion of lignocellulosic materials in animal digestive system results from the synergistic effect of various digestive enzymes and a series of physical and biochemical reactions. Microbial fermentation system is strongly supported by powerful pretreatment, such as rumination of ruminants, cellulase catalysis and alkali treatment in digestive tract of wood-eating insects. Oxygen concentration gradient along the digestive tract may stimulate the hydrolytic activity of some microorganisms. In addition, the excellent arrangement of solid retention time, digesta flow and end product discharge enhance the animal digestion of wood cellulose. Although anaerobic digestion processes inoculated with rumen microorganisms based rumen digestion mechanisms were developed to treat lignocellulose, the fermentation was more greatly limited by the environmental conditions in the anaerobic digestion reactors than that in rumen or hindgut. Therefore, the anaerobic digestion processes simulating animal digestion mechanisms can effectively enhance the degradation of wood cellulose and other organic solid wastes.

  17. Inhibitory effect of high NH{sub 4}{sup +}–N concentration on anaerobic biotreatment of fresh leachate from a municipal solid waste incineration plant

    SciTech Connect

    Liu, Zhao; Dang, Yan; Li, Caihua; Sun, Dezhi

    2015-09-15

    Highlights: • High NH{sub 4}{sup +}–N concentrations inhibit anaerobic treatment of leachate. • Inhibitory effect of NH{sub 4}{sup +}–N concentrations on anaerobic granular sludge is reversible. • High NH{sub 4}{sup +}–N concentrations inhibit bioactivities of microorganisms instead of survival. - Abstract: Fresh leachate from municipal solid waste (MSW) incineration plants generally contains extremely high NH{sub 4}{sup +}–N concentration which could inhibit the bioactivity of microorganisms. The inhibitory effect of high NH{sub 4}{sup +}–N concentration on anaerobic biotreatment of fresh leachate from a MSW incineration plant in China has been investigated in this study. The inhibition processes was studied by both static tests and a laboratory-scale expanded granular sludge bed (EGSB) reactor. The specific methanogenic activity (SMA) of the microorganisms in anaerobic granular sludge was inhibited with the NH{sub 4}{sup +}–N concentration increasing to 1000 mg/L in static tests. As well the chemical oxygen demand (COD) removal efficiency and the methane yield decreased in the EGSB reactor, while the volatile fatty acids (VFAs) accumulated and extracellular polymeric substances (EPS) of the anaerobic granular sludge increased with NH{sub 4}{sup +}–N concentration rising to 1000 mg/L, without any rebounding during 30 days of operation. Decreasing NH{sub 4}{sup +}–N concentration to 500 mg/L in influent, the COD removal efficiency recovered to about 85% after 26 days. 1000 mg/L of NH{sub 4}{sup +}–N in leachate was suggested to be the inhibition threshold in EGSB reactor. High-throughput sequencing results showed little changes in microbial communities of the sludge for a high NH{sub 4}{sup +}–N concentration, indicating that the survival of most microorganisms was not affected under such a condition. It inhibited the bioactivity of the microorganisms, resulting in decrease of the COD removal efficiency.

  18. Effects of cycle-frequency and temperature on the performance of anaerobic sequencing batch reactors (ASBRs) treating swine waste.

    PubMed

    Ndegwa, P M; Hamilton, D W; Lalman, J A; Cumba, H J

    2008-04-01

    Anaerobic digestion of animal waste is a technically viable process for the abatement of adverse environmental impacts caused by animal wastes; however, widespread acceptance has been plagued by poor economics. This situation is dismal if the technology is adapted for treating low strength animal slurries because of large digester-volume requirements and a corresponding high energy input. A possible technology to address these constraints is the anaerobic sequencing batch reactor (ASBR). The ASBR technology has demonstrated remarkable potential to improve the economics of treating dilute animal waste effluents. This paper presents preliminary data on the effects of temperature and frequency-cycle on the operation of an ASBR at a fixed hydraulic retention time (HRT). The results suggest that within the parameter range under consideration, temperature did not affect the biogas yield significantly, however, higher cycle-frequency had a negative effect. The biogas quality (%CH(4)) was not significantly affected by temperature nor by the cycle-frequency. The operating principle of the ASBR follows four phases: feed, react, settle, and decant in a cyclic mode. To improve the biogas production in an ASBR, one long react-phase was preferable compared to three shorter react-phases. Treatment of dilute manure slurries in an ASBR at 20 degrees C was more effective than at 35 degrees C; similarly more bio-stable effluents were obtained at low cycle-frequency. The treatment of dilute swine slurries in an ASBR at the lower temperature (20 degrees C) and lower cycle-frequency is, therefore, recommended for the bio-stabilization of dilute swine wastewaters. The results also indicate that significantly higher VFA degradation occurred at 20 degrees C than at 35 degrees C, suggesting that the treatment of dilute swine slurries in ASBRs for odor control might be more favorable at the lower than at the higher temperatures examined in this study. Volatile fatty acid reduction at the two

  19. [Studies on Effect of Alkali Pretreatment on Anaerobic Digestion of Rice Straw with Confocal Raman Microscopy].

    PubMed

    Xia, Yi-hua; Luo, Liu-bin; Li, Xiao-li; He, Yong; Sheng, Kui-chuan

    2015-03-01

    NaOH pretreatment is a convenient and effective method which is widely used in rice straw anaerobic digestion. But the mechanism of the alkaline (NaOH) hydrolysis of biopolymers compositions and polymeric cross-linked network structures of rice straw cell wall need further study. This paper firstly studied the effect and mechanism of alkali pretreatment on anaerobic digestion and biogas production of rice straw by using a combination of confocal Raman microscopy and transmission electron microscope. First, the original rice straw and the rice straw pretreated by NaOH were taken for mapping scanning by confocal Raman microscopy with micron-scale spatial resolution. Then principal component analysis was adopted to extract main information of Raman spectra, it could be found that the two types of samples were respectively presented with ray-like distribution in the first two principal component space, which were with cumulative contribution of 99%. And there was a clear boundary between the two types of samples without any overlapping, indicating that there was a significant difference of Raman spectral characteristic between original rice leaf and rice leaf pretreated by NaOH. Further analysis of the loading weights of the first two principal components showed that the Raman peaks at 1 739, 1 508 and 1 094 cm(-1) were the important bands, and these three Raman peaks were attributed to the scattering of hemicellulose, cellulose and lignin respectively. Following, chemical imaging analysis of hemicellulose, cellulose and lignin were achieved by combining these Raman peaks and microscopic image information. It could be found that the NaOH pretreatment resulted in a loss of dense spatial uniformity structure of tissue and great decreases of the contents of these three ingredients, particularly lignin. It can be concluded that it is feasible to non-destructively measure hemicellulose, lignin and cellulose in rice straw tissue by confocal Raman microscopy, and to achieve

  20. Effect of silver nanoparticles and antibiotics on antibiotic resistance genes in anaerobic digestion.

    PubMed

    Miller, Jennifer H; Novak, John T; Knocke, William R; Young, Katherine; Hong, Yanjuan; Vikesland, Peter J; Hull, Matthew S; Pruden, Amy

    2013-05-01

    Water resource recovery facilities have been described as creating breeding ground conditions for the selection, transfer, and dissemination of antibiotic resistance genes (ARGs) among various bacteria. The objective of this study was to determine the effect of direct addition of antibiotic and silver nanoparticles (Ag NPs, or nanosilver) on the occurrence of ARGs in thermophilic anaerobic digesters. Test thermophilic digesters were amended with environmentally-relevant concentrations of Ag NP (0.01, 0.1, and 1.0 mg-Ag/L; corresponding to approximately 0.7, 7.0, and 70 mg-Ag/kg total solids) and sulfamethoxazole (SMX) that span susceptible to resistant classifications (1, 5, and 50 mg/L) as potential selection pressures for ARGs. Tetracycline (tet(O), tet(W)) and sulfonamide (sulI, sulII) ARGs and the integrase enzyme gene (intI1) associated with Class 1 integrons were measured in raw sludge, test thermophilic digesters, a control thermophilic digester, and a control mesophilic digester. There was no apparent effect of Ag NPs on thermophilic anaerobic digester performance. The maximum SMX addition (50 mg/L) resulted in accumulation of volatile fatty acids and low pH, alkalinity, and volatile solids reduction. There was no significant difference between ARG gene copy numbers (absolute or normalized to 16S rRNA genes) in amended thermophilic digesters and the control thermophilic digester. Antibiotic resistance gene copy numbers in digested sludge ranged from 10(3) to 10(6) copies per microL (approximately 8 x10(1) to 8 x 10(4) copies per microg) of sludge as result of a 1-log reduction of ARGs (2-log reduction for intI1). Quantities of the five ARGs in raw sludge ranged from 10(4) to 10(8) copies per microL (approximately 4 x 10(2) to 4 x 10(6) per microg) of sludge. Test and control thermophilic digesters (53 degrees C, 12-day solids retention time [SRT]) consistently reduced but did not eliminate levels of all analyzed genes. The mesophilic digester (37 degrees C

  1. Physiological effects of nitrogen starvation in an anaerobic batch culture of Saccharomyces cerevisiae.

    PubMed

    Schulze, U; Lidén, G; Nielsen, J; Villadsen, J

    1996-08-01

    The effects of nitrogen starvation on the anaerobic physiology of Saccharomyces cerevisiae were studied in cells cultivated in a bioreactor. The composition of the mineral medium was designed such that the nitrogen source became depleted while there was still ample glucose left in the medium. The culture was characterized by acoustic gas analysis, flow injection analysis and HPLC analysis of extracellular substrates and metabolites. During the cultivation, the macromolecular composition of the cells was analysed with respect to the cellular content of RNA, protein, trehalose and glycogen. During exponential growth under anaerobic conditions, the maximum specific growth rate conditions. Depletion of ammonium in the medium led to an abrupt decrease (mumax) of S. cerevisiae CBS 8066 (0.46 h-1) was identical to the mumax determined under aerobic in the flux through glycolysis. Subsequently, a continuous decrease in the carbon dioxide evolution rate, caused by catabolite inactivation of the hexose-transport system, was observed. The apparent half-life of the transport system under nitrogen starvation was 13 h. During the exponential growth phase, the cellular content of RNA and protein was 15% (w/w) and 60% (w/w), respectively. At the end of the cultivation where the cells had been starved of nitrogen for 18 h, the cellular content of RNA and protein had decreased to 4% (w/w) and 22% (w/w), respectively. The intracellular carbohydrate content increased dramatically as trehalose and glycogen accumulated to final concentrations of 7% (w/w) and 25% (w/w), respectively. Glycerol formation during nitrogen starvation was higher than that accounted for by the formation of organic acids, suggesting a protein turnover of approximately 6% h-1. The growth energetics of S. cerevisiae CBS 8066 also changed as a result of nitrogen starvation, and YxATP was observed to increase from 80 mmol g-1 during the exponential growth phase to more than 130 mmol g-1 towards the end of the

  2. Inhibitory effects of butyrate on biological hydrogen production with mixed anaerobic cultures.

    PubMed

    Zheng, Xian-Jun; Yu, Han-Qing

    2005-01-01

    In this study batch experiments were conducted to investigate the inhibitory effects of butyrate addition on hydrogen production from glucose by using anaerobic mixed cultures. Experimental results showed that addition of butyrate at 4.18 and 6.27 g/l only slightly inhibited hydrogen production, and addition of butyrate at 8.36-12.54 g/l imposed a moderate inhibitory effect on hydrogen production. At addition of 25.08 g/l, butyrate had a strong inhibitory influence on substrate degradation and hydrogen production. The distribution of the volatile fatty acids produced from the acidogeneisis of glucose was significantly influenced by the addition of butyrate. The inhibition of butyrate addition on hydrogen production was described well by a non-competitive and non-linear inhibition model, with the maximum hydrogen production rate of 59.3 ml/g-SS/h, critical added butyrate concentration of 25.08 g/l, and inhibition degree of 0.323, respectively. The C(I,50) values (the butyrate concentration at which bioactivity is reduced by 50%) for hydrogen production rate and yield were estimated as 19.39 and 20.78 g/l of added butyrate, respectively.

  3. Anaerobic subsurface soil microcosms: The effect of anthropogenic organic compounds on microbial communities

    SciTech Connect

    Dougherty, J.M.

    1988-01-01

    The experiments were divided into two phases. Phase One was designed to select enzymatic activity and biomass estimation methodologies that would work well under the conditions encountered in the microcosms. Phase Two was designed to determine the effect of pollutants on the structure and activity of the indigenous microbial community by using those methods proved sensitive and efficient in Phase One. In Phase Two the microcosms were divided into three groups: control, biotic chemical, and abiotic chemical. The chemical groups received additions of three organic pollutants in varying concentrations: phenothiazine, chloronapthalene, and polychlorinated biphenyl. Microbial activity was monitored in all groups using the following enzyme assays and biomass estimates: amylase, dehydrogenase, esterase, phosphatase, protease, soil protein concentration, acridine orange direct counts, aerobic and anaerobic plate counts. Diversity indices based on gross morphology and Gram stains were computed for all plate counts. Redox potential and pH were also monitored. Significant differences were seen among groups in specific assays on specific sample dates. However, values fluctuated with time due to successional changes in the microbial consortia which made it difficult to detect changes due solely to pollutant effects.

  4. Effect of moisture on pretreatment efficiency for anaerobic digestion of lignocellulosic substrates.

    PubMed

    Peces, M; Astals, S; Mata-Alvarez, J

    2015-12-01

    The present study evaluates the effect of moisture in low-temperature and ultrasound pretreatment on lignocellulosic substrates anaerobic biodegradability, where brewer's spent grain was used as model substrate. Besides moisture content, low-temperature pretreatment was also evaluated in terms of temperature (60-80°C) and exposure time (12-72 h). Likewise, ultrasonication was also evaluated in terms of specific energy (1000-50,000 kJ kg TS(-1)). In addition, the effect of substrate particle size reduction by milling pretreatment was also considered. The results clearly demonstrated that substrate moisture (total solid concentration) is a significant parameter for pretreatment performance, although it has been rarely considered in pretreatment optimisation. Specifically, moisture optimisation increased the methane yield of brewer's spent grain by 6% for low-temperature pretreatment (60°C), and by 14% for ultrasound pretreatment (1000 kJ kg TS(-1)) towards the control (without pretreatment). In both pretreatments, the experimental optimum total solid concentration was 100 gTS kg(-1). Thus, lowering substrate moisture, a strategy suggested attaining energetic pretreatment feasibility, needs to be analysed as another pretreatment variable since it might have limited correlation. Finally, a preliminary energetic balance of the pretreatments under study showed that the extra methane production could not cover the energetic pretreatment expenses.

  5. Effect of moisture on pretreatment efficiency for anaerobic digestion of lignocellulosic substrates.

    PubMed

    Peces, M; Astals, S; Mata-Alvarez, J

    2015-12-01

    The present study evaluates the effect of moisture in low-temperature and ultrasound pretreatment on lignocellulosic substrates anaerobic biodegradability, where brewer's spent grain was used as model substrate. Besides moisture content, low-temperature pretreatment was also evaluated in terms of temperature (60-80°C) and exposure time (12-72 h). Likewise, ultrasonication was also evaluated in terms of specific energy (1000-50,000 kJ kg TS(-1)). In addition, the effect of substrate particle size reduction by milling pretreatment was also considered. The results clearly demonstrated that substrate moisture (total solid concentration) is a significant parameter for pretreatment performance, although it has been rarely considered in pretreatment optimisation. Specifically, moisture optimisation increased the methane yield of brewer's spent grain by 6% for low-temperature pretreatment (60°C), and by 14% for ultrasound pretreatment (1000 kJ kg TS(-1)) towards the control (without pretreatment). In both pretreatments, the experimental optimum total solid concentration was 100 gTS kg(-1). Thus, lowering substrate moisture, a strategy suggested attaining energetic pretreatment feasibility, needs to be analysed as another pretreatment variable since it might have limited correlation. Finally, a preliminary energetic balance of the pretreatments under study showed that the extra methane production could not cover the energetic pretreatment expenses. PMID:26316102

  6. The effects of alternative pretreatment strategies on anaerobic digestion and methane production from different algal strains.

    PubMed

    Bohutskyi, Pavlo; Betenbaugh, Michael J; Bouwer, Edward J

    2014-03-01

    The effect of various pretreatment strategies on methane yields following anaerobic digestion (AD) of five different microalgal strains was investigated. Pavlova_cf sp., Tetraselmis sp. and Thalassiosira weissflogii exhibited substantial methane yields of 0.4-0.5L/g volatile solids (VS) without pretreatment, providing up to 75-80% of theoretical values. In contrast, methane yields from Chlorella sp. and Nannochloropsis sp. were around 0.35L/g VS, or 55-60% of the theoretical values, respectively. Alkali treatment was not effective and thermal pretreatment only enhanced Nannochloropsis methane yields. Thermochemical pretreatment had the strongest impact on biomass solubilization with methane yields increasing by 30% and 40% for Chlorella and Nannochloropsis, respectively. The lipid content had a strong beneficial impact on the theoretical and observed methane yields as compared to protein and carbohydrate content. Other features such as cell-wall composition are also likely to be important factors dictating algal biodegradability and methane yields addressed in part by thermochemical pretreatment.

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

    SciTech Connect

    Silvestre, Gracia; Bonmatí, August; Fernández, Belén

    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 the 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.

  8. Effect of sawdust addition on composting of separated raw and anaerobically digested pig manure.

    PubMed

    Troy, Shane M; Nolan, Tereza; Kwapinski, Witold; Leahy, James J; Healy, Mark G; Lawlor, Peadar G

    2012-11-30

    Manures need the addition of carbon-rich bulking agents to conserve N during composting, which increases the cost of the composting process. The recommended proportion of manure/sawdust, based on a carbon (C):nitrogen (N) ratio, is approximately 3:2. Two composting experiments were conducted to determine the impact of varying the proportion of sawdust to either separated raw, or separated anaerobically digested pig manures. To determine stability and maturity of the final compost, oxygen uptake rate (OUR) and germination index (GI) tests were conducted. For both experiments, three treatments were employed: manure-only (Treatment A), manure/sawdust mixed 4:1, fresh weight (Treatment B), and manure/sawdust mixed 3:2, fresh weight (Treatment C). The mixtures were composted in tumblers for 56 days with regular turning. The composting material was tested over the study duration for temperature, pH, water content, organic matter, C:N ratio and bulk density. For both Treatments B and C, the GI indicated low levels of phytotoxicity, and OUR values were lower than the recommended Irish threshold of 13 mmol O(2) kg OM(-1) h(-1), indicating that a high quality compost was produced. The proportion of sawdust to separated manure used can be reduced to make a cost saving, while still producing a stable end-product: 60% less sawdust is required to compost at a manure-to-sawdust ratio of 4:1 compared to the previously recommended ratio of 3:2. PMID:22824375

  9. Effect of ferrous chloride on biogas production and enzymatic activities during anaerobic fermentation of cow dung and Phragmites straw.

    PubMed

    Zhang, Huayong; Tian, Yonglan; Wang, Lijun; Mi, Xueyue; Chai, Yang

    2016-06-01

    The effect of ferrous (added as FeCl2) on the anaerobic co-digestion of Phragmites straw and cow dung was studied by investigating the biogas properties, pH values, organic matter degradation (COD) and enzyme activities (cellulase, protease and dehydrogenase) at different stages of mesophilic fermentation. The results showed that Fe(2+) addition increased the cumulative biogas yields by 18.1 % by extending the peak period with high daily biogas yields. Meanwhile, the methane (CH4) contents in the Fe(2+) added groups were generally higher than the control group before the 15th day. The pH values were not significantly impacted by Fe(2+) concentrations during the fermentation process. The COD concentrations, cellulase, protease and dehydrogenase activities varied with the added Fe(2+) concentrations and the stages of the fermentation process. At the beginning stage of fermentation (4th day), Fe(2+) addition increased the biogas production by improving the cellulase and dehydrogenase activities which caused a decline in COD. At the peak stage of fermentation (8th day), Fe(2+) addition enhanced the cellulase and protease activities, and resulted in lower COD contents than the control group. When the biogas yields decreased again (13th day), the COD contents varied similar with the protease and dehydrogenase activities, whilst cellulase activities were not sensitive to Fe(2+) concentrations. At the end of fermentation (26th day), Fe(2+) addition decreased the cellulase activities, led to lower COD contents and finally resulted the lower biogas yields than the control group. Taking the whole fermentation process into account, the promoting effect of Fe(2+) addition on biogas yields was mainly attributed to the extension of the gas production peak stage and the improvement of cellulase activities. PMID:26862032

  10. Pilot-scale anaerobic co-digestion of municipal biomass waste and waste activated sludge in China: Effect of organic loading rate

    SciTech Connect

    Liu Xiao; Wang Wei; Shi Yunchun; Zheng Lei; Gao Xingbao; Qiao Wei; Zhou Yingjun

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Co-digestion of municipal biomass waste (MBW) and waste activated sludge (WAS) was examined on a pilot-scale reactor. Black-Right-Pointing-Pointer System performance and stability under OLR of 1.2, 2.4, 3.6, 4.8, 6.0 and 8.0 kg VS (m{sup 3} d){sup -1} were analyzed. Black-Right-Pointing-Pointer A maximum methane production rate of 2.94 m{sup 3} (m{sup 3} d){sup -1} was achieved at OLR of 8.0 kg VS (m{sup 3} d){sup -1} and HRT of 15d. Black-Right-Pointing-Pointer With the increasing OLRs, pH values, VS removal rate and methane concentration decreased and VFA increased. Black-Right-Pointing-Pointer The changing of biogas production rate can be a practical approach to monitor and control anaerobic digestion system. - Abstract: The effects of organic loading rate on the performance and stability of anaerobic co-digestion of municipal biomass waste (MBW) and waste activated sludge (WAS) were investigated on a pilot-scale reactor. The results showed that stable operation was achieved with organic loading rates (OLR) of 1.2-8.0 kg volatile solid (VS) (m{sup 3} d){sup -1}, with VS reduction rates of 61.7-69.9%, and volumetric biogas production of 0.89-5.28 m{sup 3} (m{sup 3} d){sup -1}. A maximum methane production rate of 2.94 m{sup 3} (m{sup 3} d){sup -1} was achieved at OLR of 8.0 kg VS (m{sup 3} d){sup -1} and hydraulic retention time of 15 days. With increasing OLRs, the anaerobic reactor showed a decrease in VS removal rate, average pH value and methane concentration, and a increase of volatile fatty acid concentration. By monitoring the biogas production rate (BPR), the anaerobic digestion system has a higher acidification risk under an OLR of 8.0 kg VS (m{sup 3} d){sup -1}. This result remarks the possibility of relating bioreactor performance with BPR in order to better understand and monitor anaerobic digestion process.

  11. Effect of Solids Retention Time on the Denitrification Potential of Anaerobically Digested Swine Waste

    NASA Astrophysics Data System (ADS)

    Kinyua, Maureen Njoki

    Three continuously stirred tank reactors (CSTR) were operated in semi continuous mode treating swine waste using anaerobic digestion. The reactors were used to test the effect of solid retention time (SRT) on CH4 yield, total ammonia nitrogen (TAN) concentrations, % volatile solids (VS), chemical oxygen demand (COD) and volatile fatty acids (VFA) removal, readily biodegradable COD concentration and the denitrification potential for the effluent in a biological nutrient removal (BNR) system. During Phase I of the study, the three reactors were operated at the same 28 day SRT for 16 weeks. SRTs were then changed during the 12 week Phase II period. The SRTs studied were 14, 21 and 28 days, with the same organic loading rate (OLR) of 1.88 ± 0.2 kg VS/ m3-day. The reactor with the lowest SRT (14 days) had the highest VS and VFA removal at 73.6 and 67.6% and lowest TAN concentration at 0.78 g NH4+-N/L, followed by the 21 day and 28 day reactors. This was likely due to the fast microbial growth rates and substrate utilization rates in this reactor compared with the other two. The 14 day reactor had the highest CH4 yield at 0.33 m3CH 4/kg VS added and readily biodegradable COD concentration at 0.93 COD/L. The variations in CH4 yield and readily biodegradable COD concentrations between the three reactors were not statistically significant. Denitrification potential for the reactors was 1.20, 0.73 and 0.56 g COD/g N for 14, 21 and 28 day reactors, respectively, and the differences were statistically significant. None of the reactors achieved a denitrification potential of 5 g COD/g N, the amount required to use effluent of anaerobically digested swine waste as an internal carbon source in a BNR. This was attributed to operating conditions such as freezing and thawing of the raw swine waste that maximized CH4 yield and lowered the readily biodegradable COD concentration. In addition the 14 day reactor had low TAN concentrations thus increasing the denitrification potential

  12. Anaerobic digestion of aliphatic polyesters.

    PubMed

    Šmejkalová, Pavla; Kužníková, Veronika; Merna, Jan; Hermanová, Soňa

    2016-01-01

    Anaerobic processes for the treatment of plastic materials waste represent versatile and effective approach in environmental protection and solid waste management. In this work, anaerobic biodegradability of model aliphatic polyesters, poly(L-lactic acid) (PLA), and poly(ɛ-caprolactone) (PCL), in the form of powder and melt-pressed films with varying molar mass, was studied. Biogas production was explored in batch laboratory trials at 55 ± 1°C under a nitrogen atmosphere. The inoculum used was thermophilic digested sludge (total solids concentration of 2.9%) from operating digesters at the Central Waste Water Treatment Plant in Prague, Czech Republic. Methanogenic biodegradation of PCLs typically yielded from 54 to 60% of the theoretical biogas yield. The biodegradability of PLAs achieved from 56 to 84% of the theoretical value. High biogas yield (up to 677 mL/g TS) with high methane content (more than 60%), comparable with conventionally processed materials, confirmed the potential of polyester samples for anaerobic treatment in the case of their exploitation in agriculture or as a packaging material in the food industry.

  13. Anaerobic digestion of aliphatic polyesters.

    PubMed

    Šmejkalová, Pavla; Kužníková, Veronika; Merna, Jan; Hermanová, Soňa

    2016-01-01

    Anaerobic processes for the treatment of plastic materials waste represent versatile and effective approach in environmental protection and solid waste management. In this work, anaerobic biodegradability of model aliphatic polyesters, poly(L-lactic acid) (PLA), and poly(ɛ-caprolactone) (PCL), in the form of powder and melt-pressed films with varying molar mass, was studied. Biogas production was explored in batch laboratory trials at 55 ± 1°C under a nitrogen atmosphere. The inoculum used was thermophilic digested sludge (total solids concentration of 2.9%) from operating digesters at the Central Waste Water Treatment Plant in Prague, Czech Republic. Methanogenic biodegradation of PCLs typically yielded from 54 to 60% of the theoretical biogas yield. The biodegradability of PLAs achieved from 56 to 84% of the theoretical value. High biogas yield (up to 677 mL/g TS) with high methane content (more than 60%), comparable with conventionally processed materials, confirmed the potential of polyester samples for anaerobic treatment in the case of their exploitation in agriculture or as a packaging material in the food industry. PMID:27191559

  14. [Effect of phosphorus recovery on phosphorous bioaccumulation/harvesting in an alternating anaerobic/aerobic biofilter system].

    PubMed

    Zhang, Shun; Tian, Qing; Tang, Man-Lin; Li, Fang

    2014-03-01

    To improve the phosphorus (P) removal/recovery efficiency of a biological P removal system, the study used an alternating anaerobic/aerobic biofilter system to treat synthetic domestic sewage with a low carbon (C) to P ratio. The effects of using periodical carbon source amplification for P recovery on the P removal efficiency and the microbial characteristics within the biofilm were investigated. Intracellular storage polymer dyeing, scanning electron microscopy (SEM) observation and fluorescence in situ hybridization (FISH) methods were employed to characterize the changes of microbial communities in the biofilm during three continuous operation cycles of P bio-accumulating-P recovery (PB-PR). The results showed: through three cycles of operation process of PB-PR, the P removal efficiency of biofilter was increased from 60.3%, 82.9%, 86.6% (before P harvesting) to 87.2%, 91.2%, 93.5% (after P harvesting), respectively; the dominant microbial community morphotypes within the biofilter transformed from big cocci to small cocci, bacilli and filamentous and the group of phosphate-accumulating organisms (PAOs) got rising predominance, which was increased from 43% to 70% after three times of PB-PR; the proportion of PAOs in the biofilm increased unceasingly with the height of the up-flow biofilter. The results showed that the periodical carbon source amplification could improve the P removal efficiency of the biofilter and help the PAOs to become the dominant bacteria within the biofilm.

  15. Phosphorus removal and N₂O production in anaerobic/anoxic denitrifying phosphorus removal process: long-term impact of influent phosphorus concentration.

    PubMed

    Wang, Zhen; Meng, Yuan; Fan, Ting; Du, Yuneng; Tang, Jie; Fan, Shisuo

    2015-03-01

    This study was conducted to investigate the long-term impact of influent phosphorus concentration on denitrifying phosphorus removal and N2O production during denitrifying phosphorous removal process. The results showed that, denitrifying phosphate accumulating organisms (DPAOs) could become dominant populations quickly in anaerobic/anoxic SBR by providing optimum cultivating conditions, and the reactor performed well for denitrifying phosphorus removal. The influent phosphorus concentration significantly affected anaerobic poly-β-hydroxyalkanoates (PHA) synthesis, denitrifying phosphorus removal, and N2O production during the denitrifying phosphorus removal process. As the influent phosphorus concentration was more than 20 mg L(-1), the activity of DPAOs began to be inhibited due to the transformation of the available carbon source type. Meanwhile, N2O production was inhibited with the mitigation of anoxic NO2(-)-N accumulation. Adoption of a modified feeding could enhance denitrifying phosphorus removal and inhibit N2O production during denitrifying phosphorous removal processes.

  16. Effect of loading rate on performance of constructed wetlands treating an anaerobic supernatant.

    PubMed

    Chazarenc, F; Maltais-Landry, G; Troesch, S; Comeau, Y; Brisson, J

    2007-01-01

    The effect of organic loading, season and plant species on the treatment of fish farm effluent was tested using three-year old mesocosm wetland systems. During one year, nine 1 m2 mesocosms (horizontal subsurface flow), located in a controlled greenhouse environment, were fed with a reconstituted fish farm effluent containing a high fraction of soluble components (1,600 microS/cm and in mg/L: 230 +/- 80 COD, 179 +/- 60 sCOD, 100 +/- 40 TSS, 37 +/- 7 TKN, 14 +/- 2 TP). Combinations of three hydraulic loading rates (30, 60 and 90 L.m(-2) d(-1)) and two plant species (Phragmites australis, Typha angustifolia) and an unplanted control were tested for treatment performance and hydraulic behaviour. Loadings higher than 15 g COD m(-2) d(-1) resulted in a net decrease of hydraulic performances (generation of short circuiting) coupled with low TKN removal. Maximal TKN removal rates (summer: 1.2, winter: 0.6 g.m(-2) d(-1)) were reached in planted units. In all mesocosms, phosphorus was removed during summer (maximal removal rate: 0.3 g TP m(-2) d(-1)) and was released in winter (release rate = approximately half of summer removal rate). This study confirmed that constructed wetlands are susceptible to clogging when treating anaerobic storage tank supernatant rich in highly biodegradable compounds. Contributions of plants to hydraulic efficiency were mainly observed in summer, associated with high evapotranspiration rates. Both plant species gave a similar removal efficiency for all pollutants.

  17. Effect of substrate loading on hydrogen production during anaerobic fermentation by Clostridium thermocellum 27405.

    PubMed

    Islam, Rumana; Cicek, Nazim; Sparling, Richard; Levin, David

    2006-09-01

    We have investigated hydrogen (H2) production by the cellulose-degrading anaerobic bacterium, Clostridium thermocellum. In the following experiments, batch-fermentations were carried out with cellobiose at three different substrate concentrations to observe the effects of carbon-limited or carbon-excess conditions on the carbon flow, H2-production, and synthesis of other fermentation end products, such as ethanol and organic acids. Rates of cell growth were unaffected by different substrate concentrations. H2, carbon dioxide (CO2), acetate, and ethanol were the main products of fermentation. Other significant end products detected were formate and lactate. In cultures where cell growth was severely limited due to low initial substrate concentrations, hydrogen yields of 1 mol H2/mol of glucose were obtained. In the cultures where growth ceased due to carbon depletion, lactate and formate represented a small fraction of the total end products produced, which consisted mainly of H2, CO2, acetate, and ethanol throughout growth. In cultures with high initial substrate concentrations, cellobiose consumption was incomplete and cell growth was limited by factors other than carbon availability. H2-production continued even in stationary phase and H2/CO2 ratios were consistently greater than 1 with a maximum of 1.2 at the stationary phase. A maximum specific H2 production rate of 14.6 mmol g dry cell(-1) h(-1) was observed. As cells entered stationary phase, extracellular pyruvate production was observed in high substrate concentration cultures and lactate became a major end product.

  18. Cultivation of Chlorella protothecoides in anaerobically treated brewery wastewater for cost-effective biodiesel production.

    PubMed

    Darpito, Cornelius; Shin, Won-Sub; Jeon, Seungjib; Lee, Hansol; Nam, Kibok; Kwon, Jong-Hee; Yang, Ji-Won

    2015-03-01

    The use of wastewater has been investigated to overcome the economic challenge involved with a production of microalgae-based biodiesel. In this study, to achieve economical biodiesel production along with effective wastewater treatment at the same time, anaerobically treated brewery wastewater (ABWW) was utilized as a low-cost nutrient source, in the cultivation of Chlorella protothecoides. About 96 and 90 % of total nitrogen and phosphorus in ABWW were removed, respectively, while C. protothecoides was accumulating 1.88 g L(-1) of biomass. The C. protothecoides grown in ABWW showed increases in cell size and cell aggregation, resulting in a near 80 % enhanced harvesting efficiency within 20 min, as compared with only 4 % in BG-11. In addition, the total fatty acid content of the C. protothecoides grown in ABWW increased by 1.84-fold (35.94 ± 1.54 % of its dry cell weight), relative to that of BG-11. PMID:25270406

  19. Effect of operational pH on biohydrogen production from food waste using anaerobic batch reactors.

    PubMed

    Lee, Chaeyoung; Lee, Sewook; Han, Sun-Kee; Hwang, Sunjin

    2014-01-01

    This study was performed to investigate the influence of operational pH on dark H(2) fermentation of food waste by employing anaerobic batch reactors. The highest maximum H(2) yield was 1.63 mol H(2)/mol hexoseadded at operational pH 5.3, whereas the lowest maximum H(2) yield was 0.88 mol H(2)/mol hexoseadded at operational pH 7.0. With decreasing operational pH values, the n-butyrate concentration tended to increase and the acetate concentration tended to decrease. The highest hydrogen conversion efficiency of 11.3% was obtained at operational pH 5.3, which was higher than that (8.3%) reported by a previous study (Kim et al. (2011) 'Effect of initial pH independent of operational pH on hydrogen fermentation of food waste', Bioresource Technology 102 (18), 8646-8652). The new result indicates that the dark fermentation of food waste was stable and efficient in this study. Fluorescence in situ hybridization (FISH) analysis showed that Clostridium species Cluster I accounted for 84.7 and 13.3% of total bacteria at operational pH 5.3 and pH 7.0, respectively, after 48 h operation.

  20. The effect of moisture regimes on the anaerobic degradation of municipal solid waste from Metepec (Mexico)

    SciTech Connect

    Hernandez-Berriel, Ma.C.

    2008-07-01

    The State of Mexico, situated in central Mexico, has a population of about 14 million, distributed in approximately 125 counties. Solid waste management represents a serious and ongoing pressure to local authorities. The final disposal site ('El Socavon') does not comply with minimum environmental requirements as no liners or leachate management infrastructure are available. Consequently, leachate composition or the effects of rain water input on municipal solid waste degradation are largely unknown. The aim of this work was to monitor the anaerobic degradation of municipal solid waste (MSW), simulating the water addition due to rainfall, under two different moisture content regimes (70% and 80% humidity). The study was carried out using bioreactors in both laboratory and pilot scales. The variation of organic matter and pH was followed in the solid matrix of the MSW. The leachate produced was used to estimate the field capacity of the MSW and to determine the pH, COD, BOD and heavy metals. Some leachate parameters were found to be within permitted limits, but further research is needed in order to analyze the leachate from lower layers of the disposal site ('El Socavon')

  1. Effect of fillers on key characteristics of sludge thermophilic anaerobic digestion.

    PubMed

    Shao, Liming; Xu, Yuanshun; Wang, Tianfeng; Lü, Fan; He, Pinjing

    2015-10-01

    In anaerobic digestion (AD) of sludge, AD efficiency and digested sludge (DS) dewaterability are critical factors. In this study, polyester non-woven fabric fillers were integrated into a sludge digester. The effect of such fillers on digestion was investigated in thermophilic temperature range in semi-continuous mode. Methane production of filler system and control reactor were significantly different (P < 0.05, paired t-test). At hydraulic retention times of 18 days and 12 days, the corresponding methane yields from filler system were 140% and 161%, respectively, of the yields from control digester without filler. Improvement of DS dewaterability was uncertain during 110 days of operation. While after a longer period of digestion, filler system resulted in a lower normalized capillary suction time of DS (76.5 ± 21.6 s L/g total suspended solids) than control reactor (118.7 ± 32.9 s L/g total suspended solids). The results showed that the filler could improve thermophilic AD performance, except at too short hydraulic retention times. PMID:26151853

  2. Correlations between bacterial populations and process parameters in four full-scale anaerobic digesters treating sewage sludge.

    PubMed

    Shin, Seung Gu; Koo, Taewoan; Lee, Joonyeob; Han, Gyuseong; Cho, Kyungjin; Kim, Woong; Hwang, Seokhwan

    2016-08-01

    Process parameters and bacterial populations were investigated in four full-scale anaerobic digesters treating sewage sludge. Although the four digesters were operated under similar conditions, digesters A and B had higher pH (7.2-7.4) and lipid removal efficiencies (>50%) than C and D (pH 6.1-6.4; average lipid removal <16%). Bacterial richness, diversity, and evenness were higher in digesters C and D. Among the top-populated genera, ten (group I) were more abundant in digesters A and/or B; they were putative syntrophic fatty acid or protein/amino acid-utilizers. In contrast, fifteen others (group II) were less abundant in A and/or B and included potentially dormant/dead cells originated from activated sludge. Despite the overall richness trend, the presence of the 25 genera in groups I/II was greater in digesters A and B (24) than in C and D (17); this observation suggests that group I bacteria might be essential in AD of sewage sludge.

  3. Bioelectrochemical treatment of paper and pulp wastewater in comparison with anaerobic process: integrating chemical coagulation with simultaneous power production.

    PubMed

    Krishna, K Vamshi; Sarkar, Omprakash; Venkata Mohan, S

    2014-12-01

    The efficiency of a bioelectrochemical treatment system (BET) to treat complex paper and pulp wastewater at two different pH conditions (6 and 7) in comparison with conventional anaerobic treatment process (AnT) was evaluated. Among the operating conditions, BET showed good treatment efficiency at pH 7 in terms of COD (BET/AnT: 55%/51%), nitrates (33.5%/19.1%), phosphates (33%/19%) and sulfates (58%/41%) in removal. The effluent obtained from BET system was subjected to coagulation for further treatment which showed good COD removal (BET/AnT, 95%/69%) and color (100%/68%). Bioelectrochemical analysis revealed higher catalytic currents in BET than AnT specific to oxidation and reduction. Besides, derivative of cyclic voltammetric scans (DCV) also supported the involvement of various membrane bound electron transferring complexes like FAD(H) bound enzymes, ubiquinone, NADH(+)/H(+) bound enzymes, etc. Experimental results demonstrated that BET system can be a viable platform to treat complex wastewaters with simultaneous energy recovery in integrated approach. PMID:25463793

  4. Bio-hydrolysis and bio-hydrogen production from food waste by thermophilic and hyperthermophilic anaerobic process.

    PubMed

    Algapani, Dalal E; Qiao, Wei; Su, Min; di Pumpo, Francesca; Wandera, Simon M; Adani, Fabrizio; Dong, Renjie

    2016-09-01

    High-temperature pretreatment plays a key role in the anaerobic digestion of food waste (FW). However, the suitable temperature is not yet determined. In this work, a long-term experiment was conducted to compare hydrolysis, acidogenesis, acetogenesis, and hydrogen production at 55°C and 70°C, using real FW in CSTR reactors. The results obtained indicated that acidification was the rate-limiting step at both temperatures with similar process kinetics characterizations. However, the thermophilic pretreatment was more advantageous than the hyperthermophilic with suspended solids solubilization of 47.7% and 29.5% and total VFA vs. soluble COD ratio of 15.2% and 4.9%, for thermophilic and hyperthermophilic treatment, respectively, with a hydrolytic reaction time (HRT) of 10days and an OLR of 14kgCOD/m(3)d. Moreover, stable hydrogen yield (70.7ml-H2/gVSin) and content in off gas (58.6%) was achieved at HRT 5days, pH 5.5, and temperature of 55°C, as opposed to 70°C.

  5. Bio-hydrolysis and bio-hydrogen production from food waste by thermophilic and hyperthermophilic anaerobic process.

    PubMed

    Algapani, Dalal E; Qiao, Wei; Su, Min; di Pumpo, Francesca; Wandera, Simon M; Adani, Fabrizio; Dong, Renjie

    2016-09-01

    High-temperature pretreatment plays a key role in the anaerobic digestion of food waste (FW). However, the suitable temperature is not yet determined. In this work, a long-term experiment was conducted to compare hydrolysis, acidogenesis, acetogenesis, and hydrogen production at 55°C and 70°C, using real FW in CSTR reactors. The results obtained indicated that acidification was the rate-limiting step at both temperatures with similar process kinetics characterizations. However, the thermophilic pretreatment was more advantageous than the hyperthermophilic with suspended solids solubilization of 47.7% and 29.5% and total VFA vs. soluble COD ratio of 15.2% and 4.9%, for thermophilic and hyperthermophilic treatment, respectively, with a hydrolytic reaction time (HRT) of 10days and an OLR of 14kgCOD/m(3)d. Moreover, stable hydrogen yield (70.7ml-H2/gVSin) and content in off gas (58.6%) was achieved at HRT 5days, pH 5.5, and temperature of 55°C, as opposed to 70°C. PMID:27295255

  6. The Effect of Different Recovery Duration on Repeated Anaerobic Performance in Elite Cyclists

    PubMed Central

    Harbili, Sultan

    2015-01-01

    This study investigated the effect of recovery duration on repeated anaerobic performance in elite cyclists. The study followed a cross-over design protocol. Twelve elite male cyclists were randomly assigned to three groups (with recovery duration of 1, 2 and 3 min, respectively). All the subjects performed 4 repeated Wingate tests (4 × 30 s WT) at 48 h intervals for three different recovery periods. No significant interaction was observed between the effects of recovery duration and repetition (p>0.05), whereas there was a significant main effect of repetition on peak power, mean power, and a fatigue index (p<0.05). Peak power decreased significantly in repeated WTs with 1 and with 2 min recovery duration (p<0.05), but it did not change significantly in a repeated WT with 3 min recovery (p>0.05). In contrast, mean power decreased significantly in repeated WTs with 1, 2 and 3 min recovery duration (p<0.05). The fatigue index increased significantly in a repeated WT with 1 min recovery duration (p<0.05), but no significant difference was observed in the fatigue index in repeated WTs with 2 and 3 min recovery (p>0.05). In a 4 × 30 s WT, peak power decreased in cycles with 1 and 2 min recovery duration, but remained unchanged with 3 min recovery duration, whereas mean power decreased in all recovery duration procedures. The WT with 1 min recovery duration caused greater fatigue. Although recovery duration affected both peak power and mean power, the effect on peak power was greater. PMID:26839617

  7. The effect of salinization and freshening events in coastal aquifers on nutrient characteristics as deduced from column experiments under aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Russak, A.; Sivan, O.; Herut, B.; Lazar, B.; Yechieli, Y.

    2015-10-01

    This study experimentally quantified the effect of seawater intrusion (salinization) and freshening events in coastal aquifers on nutrient (N, P and DSi) dynamics across the fresh-saline groundwater interface. Laboratory column experiments were conducted under aerobic and anaerobic conditions in order to simulate the processes occurring in the fresh-saline interface. They were performed with aquifer sediments, simulating the natural conditions during alterations of natural fresh groundwater to seawater and vice versa. The salinization and freshening experiments showed that NH4+ and PO43- and DSi were affected mainly by ion exchange processes while microbial activity controlled the nitrogen species NO3- and NO2-. Due to the cation exchange, salinization generated enrichment (above the expected conservative behavior) of NH4+, up to 80 μmol L-1 (an order of magnitude higher than in seawater or fresh groundwater). Under anaerobic conditions NO3- was removed by denitrification, as demonstrated by the decrease in NO3- concentrations, the increase in NO2- concentrations, and the increase in δ15N by 15-25‰. Clear evidence was shown for anion exchange of PO43-, which competes with HCO3- and boron on adsorption sites. DSi seems to take part in the exchange process, similar to PO43-.

  8. Anaerobic fermentation of beef cattle manure

    NASA Astrophysics Data System (ADS)

    Hashimoto, A. G.; Chen, Y. R.; Varel, V. H.

    1981-01-01

    The conversion of livestock manure and crop residues into methane and a high protein feed ingredient by thermophilic anaerobic fermentation is summarized. The major biological and operational factors involved in methanogenesis are discussed, and a kinetic model that describes the fermentation process is presented. Substrate biodegradability, fermentation temperature, and influent substrate concentration to have significant effects on CH4 production rate. Assessment of the energy requirements for anaerobic fermentation systems showed that the major energy requirement for a thermophilic system was for maintaining the fermenter temperature. The next major energy consumption was due to the mixing of the influent slurry and fermenter liquor. An approach to optimizing anaerobic fermenter s by selecting design criteria that maximize the net energy production per unit cost is presented.

  9. Effect of sex and menstrual cycle in women on starting speed, anaerobic endurance and muscle power.

    PubMed

    Wiecek, M; Szymura, J; Maciejczyk, M; Cempla, J; Szygula, Z

    2016-03-01

    The aim of our study was to compare the indicators of starting speed, anaerobic endurance and power in women as well as men, and to investigate whether the values of these indicators differ in women during the follicular and luteal phases of the menstrual cycle. The studied group included 16 men and 16 women. The subjects performed the 20-second maximal cycling sprint test. The men performed the test twice at 14-day intervals. The women undertook the test 4 times: twice during the middle of follicular phase and twice in the middle of luteal phase in separate menstrual cycles. Hormonal changes during the menstrual cycle do not influence anaerobic performance, starting speed or anaerobic endurance in women. Anaerobic performance in men is higher than in women with similar aerobic performance expressed as VO2max/LBM (lean body mass). A lower power decrease with time was noted for women than men, with a similar time of maintaining power in both groups. This is evidence of women's better anaerobic endurance compared to men. At the same time, the men had significantly better starting speed rates than women.

  10. Effect of sex and menstrual cycle in women on starting speed, anaerobic endurance and muscle power.

    PubMed

    Wiecek, M; Szymura, J; Maciejczyk, M; Cempla, J; Szygula, Z

    2016-03-01

    The aim of our study was to compare the indicators of starting speed, anaerobic endurance and power in women as well as men, and to investigate whether the values of these indicators differ in women during the follicular and luteal phases of the menstrual cycle. The studied group included 16 men and 16 women. The subjects performed the 20-second maximal cycling sprint test. The men performed the test twice at 14-day intervals. The women undertook the test 4 times: twice during the middle of follicular phase and twice in the middle of luteal phase in separate menstrual cycles. Hormonal changes during the menstrual cycle do not influence anaerobic performance, starting speed or anaerobic endurance in women. Anaerobic performance in men is higher than in women with similar aerobic performance expressed as VO2max/LBM (lean body mass). A lower power decrease with time was noted for women than men, with a similar time of maintaining power in both groups. This is evidence of women's better anaerobic endurance compared to men. At the same time, the men had significantly better starting speed rates than women. PMID:27030635

  11. Process model for ammonia volatilization from anaerobic swine lagoons incorporating varying wind speeds and biogas bubbling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ammonia volatilization from treatment lagoons varies widely with the total ammonia concentration, pH, temperature, suspended solids, atmospheric ammonia concentration above the water surface, and wind speed. Ammonia emissions were estimated with a process-based mechanistic model integrating ammonia ...

  12. Lab-scale demonstration of recuperative thickening technology for enhanced biogas production and dewaterability in anaerobic digestion processes.

    PubMed

    Cobbledick, Jeffrey; Aubry, Nicholas; Zhang, Victor; Rollings-Scattergood, Sasha; Latulippe, David R

    2016-05-15

    There is growing interest in the use of high performance anaerobic digestion (AD) processes for the production of biogas at wastewater treatment facilities to offset the energy demands associated with wastewater treatment. Recuperative thickening (RT) is a promising technique which involves recycling a portion of the digested solids back to the incoming feed. In general there exists a significant number of knowledge gaps in the field of RT because the studies that have been conducted to date have almost exclusively occurred in pilot plant or full scale trials; this approach greatly limits the amount of process optimization that can be done in a given trial. In this work, a detailed and comprehensive study of RT was conducted at the lab scale; two custom designed digesters (capacity = 1.5 L) were operated in parallel with one acting as a 'control' digester and the other operating under a semi-batch RT mode. There was no significant change in biogas methane composition for the two digesters, however the RT digester had an average biogas productivity over two times higher than the control one. It was found that the recycling of the polymer flocculant back into the RT digester resulted in a significant improvement in dewatering performance. At the highest polymer concentration tested, the capillary suction time (CST) values for flocculated samples for the RT digester were over 6 times lower than the corresponding values for the control digester. Thus, there exists an opportunity to decrease the overall consumption of polymer flocculants through judicious selection of the dose of polymer flocculant that is used both for the thickening and end-stage dewatering steps in RT processes. PMID:26986495

  13. Potential of hydrolysis of particulate COD in extended anaerobic conditions to enhance biological phosphorous removal.

    PubMed

    Jabari, P; Yuan, Q; Oleszkiewicz, J A

    2016-11-01

    The effect of anaerobic hydrolysis of particulate COD (pCOD) on biological phosphorous removal in extended anaerobic condition was investigated through (i) sequencing batch reactors (SBR)s with anaerobic hydraulic retention time (HRT) of 0.8, 2, and 4 h; (ii) batch tests using biomass from a full scale biological nutrient removal (BNR) plant; and (iii) activated sludge modeling (BioWin 4.1 simulation). The results from long-term SBRs operation showed that phosphorus removal was correlated to the ratio of filtered COD (FCOD) to total phosphorus (TP) in the influent. Under conditions with low FCOD/TP ratio (average of 20) in the influent, extending anaerobic HRT to 4 h in the presence of pCOD did not significantly improve overall phosphorous removal. During the period with high FCOD/TP ratio (average of 37) in the influent, all SBRs removed phosphorous completely, and the long anaerobic HRT did not have negative effect on overall phosphorous removal. The batch tests also showed that pCOD at different concentration during 4 h test did not affect the rate of anaerobic phosphorus release. The rate of anaerobic hydrolysis of pCOD was significantly low and extending the anaerobic HRT was ineffective. The simulation (BioWin 4.1) of SBRs with low influent FCOD/TP ratio showed that the default kinetics of anaerobic hydrolysis in ASM2d overestimated phosphorous removal in the SBRs (high anaerobic hydrolysis of pCOD). The default anaerobic hydrolysis rate in BioWin 4.1 (ten times lower) could produce similar phosphorous removal to that in the experiment. Results showed that the current kinetics of anaerobic hydrolysis in ASM2d could lead to considerable error in predicting phosphorus removal in processes with extended anaerobic HRT. Biotechnol. Bioeng. 2016;113: 2377-2385. © 2016 Wiley Periodicals, Inc.

  14. Occurrence and removal of six pharmaceuticals and personal care products in a wastewater treatment plant employing anaerobic/anoxic/aerobic and UV processes in Shanghai, China.

    PubMed

    Wang, Dan; Sui, Qian; Lu, Shu-Guang; Zhao, Wen-Tao; Qiu, Zhao-Fu; Miao, Zhou-Wei; Yu, Gang

    2014-03-01

    The occurrence and removal of six pharmaceuticals and personal care products (PPCPs) including caffeine (CF), N, N-diethyl-meta-toluamide (DEET), carbamazepine, metoprolol, trimethoprim (TMP), and sulpiride in a municipal wastewater treatment plant (WWTP) in Shanghai, China were studied in January 2013; besides, grab samples of the influent were also taken every 6 h, to investigate the daily fluctuation of the wastewater influent. The results showed the concentrations of the investigated PPCPs ranged from 17 to 11,400 ng/L in the WWTP. A low variability of the PPCP concentrations in the wastewater influent throughout the day was observed, with the relative standard deviations less than 25 % for most samples. However, for TMP and CF, the slight daily fluctuation still reflected their consumption patterns. All the target compounds except CF and DEET, exhibited poor removal efficiencies (<40 %) by biological treatment process, probably due to the low temperature in the bioreactor, which was unfavorable for activated sludge. While for the two biodegradable PPCPs, CF, and DEET, the anaerobic and oxic tank made contributions to their removal while the anoxic tank had a negative effect to their elimination. The tertiary UV treatment removed the investigated PPCPs by 5-38 %, representing a crucial polishing step to compensate for the poor removal by the biologic treatment process in winter.

  15. 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.

  16. 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. PMID:26139136

  17. Benefit of sodium hydroxide pretreatment of ensiled sorghum forage on the anaerobic reactor stability and methane production.

    PubMed

    Sambusiti, C; Ficara, E; Malpei, F; Steyer, J P; Carrère, H

    2013-09-01

    The assessment of the pretreatment effect on the anaerobic digestion process is generally based on the results of batch tests, which may fail in truly predicting full-scale anaerobic reactors performance. Therefore, in this study, the effect of alkaline pretreatment on the anaerobic digestion of ensiled sorghum forage was evaluated by comparing the results of two semi-continuous CSTR (Continuously Stirred Tank Reactor) anaerobic reactors. Results showed that an alkaline pretreatment step, prior to the anaerobic digestion of ensiled sorghum forage, can have a beneficial effect both in enhancing methane production (an increase of 25% on methane production was observed, if compared to that of untreated sorghum) and in giving more stability to the anaerobic digestion process.

  18. Effects of dairy manure and corn stover co-digestion on anaerobic microbes and corresponding digestion performance.

    PubMed

    Yue, Zhengbo; Chen, Rui; Yang, Fan; MacLellan, James; Marsh, Terence; Liu, Yan; Liao, Wei

    2013-01-01

    This study investigated the effects of corn stover as a supplemental feed on anaerobic digestion of dairy manure under different hydraulic retention times (HRT). The results elucidated that both HRT and corn stover supplement significantly influenced microbial community and corresponding anaerobic digestion performance. The highest biogas production of 497 mL per gram total solid loading per day was observed at a HRT of 40 days from digestion of manure supplemented with corn stover. Biogas production was closely correlated with the populations of Bacteroidetes, Clostridia and methanogens. Composition of the solid digestate (AD fiber) from the co-digestion of corn stover and dairy manure was similar to the digestion of dairy manure. However, the hydrolysis of AD fiber was significantly (P < 0.05) different among the different digestions. Both HRT and feed composition influenced the hydrolyzability of AD fiber via shifting the composition of microbial community.

  19. Effect of different nitroheterocyclic compounds on aerobic, microaerophilic, and anaerobic bacteria.

    PubMed Central

    Hof, H; Ströder, J; Buisson, J P; Royer, R

    1986-01-01

    The antibacterial activities of different nitroheterocyclic compounds were assessed by an agar dilution method against aerobic, microaerophilic, and anaerobic bacteria. Nitronaphthofurans inhibited the multiplication of aerobic bacteria at low concentrations (MIC for 50% of strains tested [MIC50], 1 mg/liter). Under anaerobic growth conditions the MICs were found to be even lower. The rough, DNA repair-deficient mutants of Salmonella typhimurium were more susceptible, whereas nitroreductase-deficient strains were resistant. Microaerophilic campylobacter isolates could be divided into two groups, one of which was as susceptible as aerobic bacteria (MIC50, 1 mg/liter) and the other of which was more highly susceptible (MIC50, 0.015 mg/liter). All anaerobic bacteria tested were susceptible to nitronaphthofurans (MIC50, 0.125 mg/liter). Nitrothiazole exerted antibacterial activities similar to those of the nitronaphthofurans. Metronidazole, a nitroimidazole derivative, and nitrofurans were definitely less active. Nitrobenzofurans showed relatively high MICs. PMID:3800344

  20. High frequency ultrasound pretreatment for sludge anaerobic digestion: effect on floc structure and microbial population.

    PubMed

    Braguglia, C M; Gagliano, M C; Rossetti, S

    2012-04-01

    In this work the potential of high frequency ultrasounds as pretreatment for sludge anaerobic digestion has been assessed. Irradiation with 200kHz ultrasounds was efficient in disintegrating the floc structure increasing the available fraction of soluble organic matter (up to seven times at 25,000kJ/kgTS). Batch anaerobic digestion tests were carried out on lab-scale reactors fed either with untreated or disintegrated sludge inoculated with anaerobic sludge, at different feed/inoculum ratio (F/I=0.5 and 1). Degradation of particulate matter, biogas production and related microbial community composition (estimated by fluorescence in situ hybridization, FISH) were investigated. Sludge ultrasounds pretreatment led to an overall improvement of the digestion performances, with a maximum biogas gain of 40% at F/I=0.5. FISH showed a key-role of Methanosarcina spp. in the main reactions of biogas synthesis.

  1. Influence of co-substrate on textile wastewater treatment and microbial community changes in the anaerobic biological sulfate reduction process.

    PubMed

    Rasool, Kashif; Mahmoud, Khaled A; Lee, Dae Sung

    2015-12-15

    This study investigated the anaerobic treatment of sulfate-rich synthetic textile wastewater in three sulfidogenic sequential batch reactors (SBRs). The experimental protocol was designed to examine the effect of three different co-substrates (lactate, glucose, and ethanol) and their concentrations on wastewater treatment performance. Sulfate reduction and dye degradation were improved when lactate and ethanol were used as electron donors, as compared with glucose. Moreover, under co-substrate limited concentrations, color, sulfate, and chemical oxygen demand (COD) removal efficiencies were declined. By reducing co-substrate COD gradually from 3000 to 500 mg/L, color removal efficiencies were decreased from 98.23% to 78.46%, 63.37%, and 69.10%, whereas, sulfate removal efficiencies were decreased from 98.42%, 82.35%, and 87.0%, to 30.27%, 21.50%, and 10.13%, for lactate, glucose, and ethanol fed reactors, respectively. Fourier transform infrared spectroscopy (FTIR) and total aromatic amine analysis revealed lactate to be a potential co-substrate for further biodegradation of intermediate metabolites formed after dye degradation. Pyrosequencing analysis showed that microbial community structure was significantly affected by the co-substrate. The reactor with lactate as co-substrate showed the highest relative abundance of sulfate reducing bacteria (SRBs), followed by ethanol, whereas the glucose-fed reactor showed the lowest relative abundance of SRB. PMID:26241771

  2. Enhanced methane production from rice straw co-digested with anaerobic sludge from pulp and paper mill treatment process.

    PubMed

    Mussoline, Wendy; Esposito, Giovanni; Lens, Piet; Spagni, Alessandro; Giordano, Andrea

    2013-11-01

    Rice straw is a widely available lignocellulosic waste with potential for energy recovery through anaerobic digestion. Lignin slows the hydrolysis phase, resulting in low methane recovery and long digestion periods. Although pretreatment is effective, it often requires high energy inputs or chemicals that are not feasible for farm-scale systems. This study investigates a unique co-digestion strategy to improve methane yields and reduce digestion times for farm-scale systems. By adding both piggery wastewater and paper mill sludge, specific methane yields in laboratory-scale digesters reached the theoretical value for rice straw (i.e. 330LNCH4/kgVS) over the 92-day period. Accelerated hydrolysis of the straw was directly related to the quantity of sludge added. The most stable digester, with sufficient buffering capacity and nutrients, contained equal parts of straw, wastewater and sludge. This approach is feasible for farm-scale applications since it requires no additional energy inputs or changes to existing infrastructure for dry systems.

  3. Anaerobic treatment

    SciTech Connect

    Witt, E.R.; Humphrey, W.J.; Cave, J.P.

    1982-12-28

    This invention provides for the anaerobic treatment of acidic petrochemical wastes in an anaerobic filter at high loadings and high recycle rates. The effluent from the top of the filter passes into a gas-disengaging/solids-settling zone containing a quiescent body of the effluent liquid. The settled solids are withdrawn and recycled to the base of the filter together with fresh acidic waste and an inorganic alkaline material (preferably magnesium oxide or carbonate) to maintain a neutral pH. The liquid portion of the effluent is sent to an aerobic digester to remove the rest of the organic material, which is used to support the growth of bacteria and fed back to the anaerobic system.

  4. Effects of acetate, propionate, and butyrate on the thermophilic anaerobic degradation of propionate by methanogenic sludge and defined cultures

    SciTech Connect

    Lier, J.B. van; Grolle, K.C.F.; Frijters, C.T.M.J.; Stams, A.J.M.; Lettinga, G. )

    1993-04-01

    Acetate, propionate, and butyrate are intermediate products in the anaerobic bioconversion of organic matter to methane and carbon dioxide. This study examines the effects of acetate, propionate, and butyrate on the thermophilic oxidation of propionate in continuous-flow methanogenic sludge bed systems and in defined propionate-oxidizing cultures. Volatile fatty acids (VFA) in sludge inhibit thermophilic anaerobic oxidation of propionate, dependent on the concentration and on the pH. Addition of butyrate-oxidizing acetogens to the media eliminate the inhibitory effect of butyrate and stimulated propionate conversion. In the propionate-oxidizing enrichment, and to a lesser extent in the UASB reactor, culture growth was affected by acetate. However, the relationship between acetate concentrations and propionate degradation was not clear. Hydrogen is an important intermediate of thermophilic propionate conversion. This study found that propionate oxidation was severely inhibited with no increase in the hydrogen partial pressure in the biogas. As a result, the authors conclude the suitability of hydrogen as a n overall control parameter for anaerobic digestion has to be reconsidered. 29 refs., 6 figs., 2 tabs.

  5. Effect of migration and transformation of iron on the endogenous reduction of H2S in anaerobic landfill.

    PubMed

    Long, Yu-Yang; Du, Yao; Fang, Yuan; Xu, Jing; He, Yan-Ni; Shen, Dong-Sheng

    2016-07-01

    Hydrogen sulfide (H2S) is a major odor in landfill gas and needs urgent treatment. In this study, the effect of migration and transformation of iron on the endogenous reduction of H2S was investigated in two simulated landfills. The results showed that the H2S emission concentration from the landfill cover of conventional anaerobic landfill (CL) and anaerobic landfill with leachate recirculation (RL) could reach 19.4mgm(-3) and 24.1mgm(-3), respectively. However, the migration and transformation of iron in anaerobic landfill with different operational modes results in different endogenous reduction mechanism for H2S. The proportion of precipitation-reduction mechanism and oxidation-reduction mechanism in CL was 73.3% and 26.3%, respectively. But for RL, the function of oxidation was enhanced, and the sulfide content was reduced 23.1% compared with CL. The iron in landfill with leachate recirculation revealed good endogenous reduction effect on H2S control after a period of time landfilling. PMID:26584556

  6. Hydrogen production from the dissolution of nano zero valent iron and its effect on anaerobic digestion.

    PubMed

    Huang, Yu-Xi; Guo, Jialiang; Zhang, Chunyang; Hu, Zhiqiang

    2016-01-01

    Nano zero valent iron (NZVI) has shown inhibition on methanogenesis in anaerobic digestion due to its reductive decomposition of cell membrane. The inhibition was accompanied by the accumulation of hydrogen gas due to rapid NZVI dissolution. It is not clear whether and how rapid hydrogen release from NZVI dissolution directly affects anaerobic digestion. In this study, the hydrogen release kinetics from NZVI (average size = 55 ± 11 nm) dissolution in deionized water under anaerobic conditions was first evaluated. The first-order NZVI dissolution rate constant was 2.62 ± 0.26 h(-1) with its half-life of 0.26 ± 0.03 h. Two sets of anaerobic digestion experiments (i.e., in the presence of glucose or without any substrate but at different anaerobic sludge concentrations) were performed to study the impact of H2 release from rapid NZVI dissolution, in which H2 was generated in a separate water bottle containing NZVI (i.e., ex situ H2 or externally supplied from NZVI dissolution) before hydrogen gas was introduced to anaerobic digestion. The results showed that the H2 partial pressure in the headspace of the digestion bottle reached as high as 0.27 atm due to rapid NZVI dissolution, resulting in temporary inhibition of methane production. Nevertheless, the 5-d cumulative methane volume in the group with ex situ H2 production due to NZVI dissolution was actually higher than that of control, suggesting NZVI inhibition on methanogenesis is solely due to the reductive decomposition of cell membrane after direct contact with NZVI. PMID:26521217

  7. Hydrogen production from the dissolution of nano zero valent iron and its effect on anaerobic digestion.

    PubMed

    Huang, Yu-Xi; Guo, Jialiang; Zhang, Chunyang; Hu, Zhiqiang

    2016-01-01

    Nano zero valent iron (NZVI) has shown inhibition on methanogenesis in anaerobic digestion due to its reductive decomposition of cell membrane. The inhibition was accompanied by the accumulation of hydrogen gas due to rapid NZVI dissolution. It is not clear whether and how rapid hydrogen release from NZVI dissolution directly affects anaerobic digestion. In this study, the hydrogen release kinetics from NZVI (average size = 55 ± 11 nm) dissolution in deionized water under anaerobic conditions was first evaluated. The first-order NZVI dissolution rate constant was 2.62 ± 0.26 h(-1) with its half-life of 0.26 ± 0.03 h. Two sets of anaerobic digestion experiments (i.e., in the presence of glucose or without any substrate but at different anaerobic sludge concentrations) were performed to study the impact of H2 release from rapid NZVI dissolution, in which H2 was generated in a separate water bottle containing NZVI (i.e., ex situ H2 or externally supplied from NZVI dissolution) before hydrogen gas was introduced to anaerobic digestion. The results showed that the H2 partial pressure in the headspace of the digestion bottle reached as high as 0.27 atm due to rapid NZVI dissolution, resulting in temporary inhibition of methane production. Nevertheless, the 5-d cumulative methane volume in the group with ex situ H2 production due to NZVI dissolution was actually higher than that of control, suggesting NZVI inhibition on methanogenesis is solely due to the reductive decomposition of cell membrane after direct contact with NZVI.

  8. Effect of agitation on the performance of an anaerobic sequencing batch biofilm reactor in the treatment of dairy effluents.

    PubMed

    Penteado, T Z; Santana, R S S; Dibiazi, A L B; de Pinho, S C; Ribeiro, R; Tommaso, G

    2011-01-01

    Agitation rate is an important parameter in the operation of Anaerobic Sequencing Biofilm Batch Reactors (ASBBRs), and a proper agitation rate guarantees good mixing, improves mass transfer, and enhances the solubility of the particulate organic matter. Dairy effluents have a high amount of particulate organic matter, and their anaerobic digestion presents inhibitory intermediates (e.g., long-chain fatty acids). The importance of studying agitation in such batch systems is clear. The present study aimed to evaluate how agitation frequency influences the anaerobic treatment of dairy effluents. The ASBBR was fed with wastewater from milk pasteurisation process and cheese manufacture with no whey segregation. The organic matter concentration, measured as chemical oxygen demand (COD), was maintained at approximately 8,000 mg/L. The reactor was operated with four agitation frequencies: 500 rpm, 350 rpm, 200 rpm, and no agitation. In terms of COD removal efficiency, similar results were observed for 500 rpm and 350 rpm (around 90%) and for 200 rpm and no agitation (around 80%). Increasing the system's agitation thus not only improved the global efficiency of organic matter removal but also influenced volatile acid production and consumption and clearly modified this balance in each experimental condition. PMID:21411951

  9. Effect of agitation on the performance of an anaerobic sequencing batch biofilm reactor in the treatment of dairy effluents.

    PubMed

    Penteado, T Z; Santana, R S S; Dibiazi, A L B; de Pinho, S C; Ribeiro, R; Tommaso, G

    2011-01-01

    Agitation rate is an important parameter in the operation of Anaerobic Sequencing Biofilm Batch Reactors (ASBBRs), and a proper agitation rate guarantees good mixing, improves mass transfer, and enhances the solubility of the particulate organic matter. Dairy effluents have a high amount of particulate organic matter, and their anaerobic digestion presents inhibitory intermediates (e.g., long-chain fatty acids). The importance of studying agitation in such batch systems is clear. The present study aimed to evaluate how agitation frequency influences the anaerobic treatment of dairy effluents. The ASBBR was fed with wastewater from milk pasteurisation process and cheese manufacture with no whey segregation. The organic matter concentration, measured as chemical oxygen demand (COD), was maintained at approximately 8,000 mg/L. The reactor was operated with four agitation frequencies: 500 rpm, 350 rpm, 200 rpm, and no agitation. In terms of COD removal efficiency, similar results were observed for 500 rpm and 350 rpm (around 90%) and for 200 rpm and no agitation (around 80%). Increasing the system's agitation thus not only improved the global efficiency of organic matter removal but also influenced volatile acid production and consumption and clearly modified this balance in each experimental condition.

  10. Model-based evaluation of microbial mass fractions: effect of absolute anaerobic reaction time on microbial mass fractions.

    PubMed

    Tunçal, Tolga

    2010-04-14

    Although enhanced biological phosphorus removal processes (EBPR) are popular methods for nutrient control, unstable treatment performances of full-scale systems are still not well understood. In this study, the interaction between electron acceptors present at the start of the anaerobic phase of an EBPR system and the amount of organic acids generated from simple substrate (rbsCOD) was investigated in a full-scale wastewater treatment plant. Quantification of microbial groups including phosphorus-accumulating microorganisms (PAOs), denitrifying PAOs (DPAOs), glycogen-accumulating microorganisms (GAOs) and ordinary heterotrophic microorganisms (OHOs) was based on a modified dynamic model. The intracellular phosphorus content of PAOs was also determined by the execution of mass balances for the biological stages of the plant. The EBPR activities observed in the plant and in batch tests (under idealized conditions) were compared with each other statistically as well. Modelling efforts indicated that the use of absolute anaerobic reaction (eta1) instead of nominal anaerobic reaction time (eta), to estimate the amount of available substrate for PAOs, significantly improved model accuracy. Another interesting result of the study was the differences in EBPR characteristics observed in idealized and real conditions. PMID:20480829

  11. Geochemical and microbiological methods for evaluating anaerobic processes in an aquifer contaminated by landfill leachate

    USGS Publications Warehouse

    Cozzarelli, I.M.; Suflita, J.M.; Ulrich, G.A.; Harris, S.H.; Scholl, M.A.; Schlottmann, J.L.; Christenson, S.

    2000-01-01

    A combined geochemical and microbiological approach was needed to delineate the biogeochemical processes occurring in an aquifer contaminated by landfill leachate in Norman, OK, where the important microbially mediated reactions in an anoxic plume were iron reduction, sulfate reduction, and methanogenesis. The highest rates of sulfate reduction (13.2 ??M/day) were detected near the water table where sulfate levels were maximal (up to 4.6 mM). The enrichment of 34S in the sulfate pools (??34S of SO42- was 67-69%0), and dissolved hydrogen measurements provided additional support for the importance of sulfate reduction near the water table. Methane was detected in the center of the plume where sulfate was depleted. Microbial incubations demonstrated concomitant sulfate reduction and methanogenesis in the anoxic portion of the plume. Although high concentrations of soluble reduced iron were detected throughout the aquifer and H2 levels were indicative of iron reduction under steady-state conditions, microbiological experiments showed that iron reduction was active only at the edges of the sulfate-depleted portion of the plume. This study demonstrates the benefits of using a combined geochemical and microbiological approach to elucidate the spatial distribution of biogeochemical processes in contaminated aquifers.A combined geochemical and microbiological approach was needed to delineate the biogeochemical processes occurring in an aquifer contaminated by landfill leachate in Norman, OK, where the important microbially mediated reactions in an anoxic plume were iron reduction, sulfate reduction, and methanogenesis. The highest rates of sulfate reduction (13.2 ??M/day) were detected near the water table where sulfate levels were maximal (up to 4.6 mM). The enrichment of 34S in the sulfate pools (??34S of SO42- was 67-69 per mil), and dissolved hydrogen measurements provided additional support for the importance of sulfate reduction near the water table. Methane was

  12. Inhibition effects of high calcium concentration on anaerobic biological treatment of MSW leachate.

    PubMed

    Xia, Yi; He, Pin-Jing; Pu, Hong-Xia; Lü, Fan; Shao, Li-Ming; Zhang, Hua

    2016-04-01

    With the increasing use of municipal solid waste incineration (MSWI) and more stringent limits on landfilling of organic waste, more MSWI bottom ash is being landfilled, and the proportion of inorganic wastes in landfills is increasing, causing the increased Ca concentrations in landfill leachate. In this research, the inhibition effect of Ca concentration on the anaerobic treatment of landfill leachate was studied using a biochemical methane potential experiment. Slight inhibition of methane production occurred when the addition of Ca concentration was less than 2000 mg/L. When the addition of Ca concentration was between 6000 and 8000 mg/L, methane production was significantly reduced (to 29.4-34.8 % of that produced by the BLK reactor), and the lag phase was increased from 8.55 to 16.32 d. Moreover, when the dosage of Ca concentration increased from zero to 8000 mg/L, reductions in solution Ca concentration increased from 929 to 2611 mg/L, and the proportion of Ca in the residual sludge increased from 22.58 to 46.87 %. Based on the results, when the dosage of Ca concentration was less than 4000 mg/L, the formation of Ca precipitates on the surface of sludge appeared to prevent mass transfer and was the dominant reason for the reduction in methane production and sludge biomass. At higher Ca concentrations (6000-8000 mg/L), the severe inhibition of methane production appeared to be caused by the toxic effect of highly concentrated Ca on sludge as well as mass transfer blockage. PMID:26769478

  13. Effect of microwave hydrolysis on transformation of steroidal hormones during anaerobic digestion of municipal sludge cake.

    PubMed

    Hamid, Hanna; Eskicioglu, Cigdem

    2013-09-15

    Fate and removal of 16 steroidal (estrogenic, androgenic and progestogenic) hormones were studied during advanced anaerobic digestion of sludge cake using microwave (MW) pretreatment. Effect of pretreatment temperature (80, 120, 160 °C), operating temperature (mesophilic at 35 ± 2 °C, thermophilic at 55 ± 2 °C) and sludge retention time (SRT: 20, 10, 5 days) were studied employing eight lab-scale semi-continuously fed digesters. To determine the potential effect of MW hydrolysis, hormones were quantified in total (sorbed + soluble) and supernatant (soluble) phases of the digester influent and effluent streams. Seven of 16 hormones were above the method reporting limit (RL) in one or more of the samples. Hormone concentrations in total phase of un-pretreated (control) and pretreated digester feeds ranged in <157-2491 ng/L and <157-749 ng/L, respectively. The three studied factors were found to be statistically significant (95% confidence level) in removal of one or more hormones from soluble and/or total phase. MW hydrolysis of the influent resulted in both release (from sludge matrix) and attenuation of hormones in the soluble phase. Accumulation of estrone (E1) as well as progesterone (Pr) and androstenedione (Ad) in most of the digesters indicated possible microbial transformations among the hormones. Compared to controls, all pretreated digesters had lower total hormone concentrations in their influent streams. At 20 days SRT, highest total removal (E1+E2+Ad +Pr) was observed for the thermophilic control digester (56%), followed by pretreated mesophilic digesters at 120 °C and 160 °C with around 48% efficiency. In terms of conventional performance parameters, relative (to control) improvements of MW pretreated digesters at a 5-d SRT ranged in 98-163% and 57-121%, for volatile solids removal and methane production, respectively.

  14. The effects of creatine monohydrate loading on anaerobic performance and one-repetition maximum strength.

    PubMed

    Zuniga, Jorge M; Housh, Terry J; Camic, Clayton L; Hendrix, C Russell; Mielke, Michelle; Johnson, Glen O; Housh, Dona J; Schmidt, Richard J

    2012-06-01

    The purpose of this study was to examine the effects of 7 days of supplementation with 20 g·d⁻¹ of creatine monohydrate (CM) on mean power (MP) and peak power (PP) from the Wingate anaerobic test (WAnT), body weight (BW), 1-repetition maximum (1RM) bilateral leg extension (LE) strength, and 1RM bench press (BP) strength. This study used a randomized, double-blind, placebo-controlled design. Twenty-two men (mean ± SD: age = 22.1 ± 2.0 years; height = 178.0 ± 5.8 cm; body weight [BW] = 77.6 ± 7.6 kg) were randomly assigned to either a supplement (SUPP; n = 10) or placebo (PLAC; n = 12) group. The SUPP group ingested 20 g·d⁻¹ of CM powder for 7 days, whereas the PLAC ingested 20 g·d⁻¹ of maltodextrin powder. Measurements for the PLAC and SUPP groups included BW, PP, and MP from two 30-second WAnTs (separated by 7 minutes), and 1RM strength for LE and BP. Testing was conducted before (PRE) and after (POST) 7 days of ingesting either the supplement or placebo. The results of this study indicated that there was a significant (p ≤ 0.05) increase from PRE to POST testing in MP for the SUPP group (5.4%) but not for the PLAC group (-0.3%). There were no between-group differences, however, for 1RM LE and 1RM BP strength. Furthermore, there were no changes in PP or BW for either group. The findings of this study indicated that loading with 20 g·d⁻¹ of CM for 7 days increased MP (5.4% increase) from the WAnT, but it had no effect on strength (1RM LE and 1RM BP), PP, or BW.

  15. The Effects of High Intensity Interval Training vs Steady State Training on Aerobic and Anaerobic Capacity

    PubMed Central

    Foster, Carl; Farland, Courtney V.; Guidotti, Flavia; Harbin, Michelle; Roberts, Brianna; Schuette, Jeff; Tuuri, Andrew; Doberstein, Scott T.; Porcari, John P.

    2015-01-01

    High intensity interval training (HIIT) has become an increasingly popular form of exercise due to its potentially large effects on exercise capacity and small time requirement. This study compared the effects of two HIIT protocols vs steady-state training on aerobic and anaerobic capacity following 8-weeks of training. Fifty-five untrained college-aged subjects were randomly assigned to three training groups (3x weekly). Steady-state (n = 19) exercised (cycle ergometer) 20 minutes at 90% of ventilatory threshold (VT). Tabata (n = 21) completed eight intervals of 20s at 170% VO2max/10s rest. Meyer (n = 15) completed 13 sets of 30s (20 min) @ 100% PVO2 max/ 60s recovery, average PO = 90% VT. Each subject did 24 training sessions during 8 weeks. Results: There were significant (p < 0.05) increases in VO2max (+19, +18 and +18%) and PPO (+17, +24 and +14%) for each training group, as well as significant increases in peak (+8, + 9 and +5%) & mean (+4, +7 and +6%) power during Wingate testing, but no significant differences between groups. Measures of the enjoyment of the training program indicated that the Tabata protocol was significantly less enjoyable (p < 0.05) than the steady state and Meyer protocols, and that the enjoyment of all protocols declined (p < 0.05) across the duration of the study. The results suggest that although HIIT protocols are time efficient, they are not superior to conventional exercise training in sedentary young adults. Key points Steady state training equivalent to HIIT in untrained students Mild interval training presents very similar physiologic challenge compared to steady state training HIIT (particularly very high intensity variants were less enjoyable than steady state or mild interval training Enjoyment of training decreases across the course of an 8 week experimental training program PMID:26664271

  16. Effect of microwave hydrolysis on transformation of steroidal hormones during anaerobic digestion of municipal sludge cake.

    PubMed

    Hamid, Hanna; Eskicioglu, Cigdem

    2013-09-15

    Fate and removal of 16 steroidal (estrogenic, androgenic and progestogenic) hormones were studied during advanced anaerobic digestion of sludge cake using microwave (MW) pretreatment. Effect of pretreatment temperature (80, 120, 160 °C), operating temperature (mesophilic at 35 ± 2 °C, thermophilic at 55 ± 2 °C) and sludge retention time (SRT: 20, 10, 5 days) were studied employing eight lab-scale semi-continuously fed digesters. To determine the potential effect of MW hydrolysis, hormones were quantified in total (sorbed + soluble) and supernatant (soluble) phases of the digester influent and effluent streams. Seven of 16 hormones were above the method reporting limit (RL) in one or more of the samples. Hormone concentrations in total phase of un-pretreated (control) and pretreated digester feeds ranged in <157-2491 ng/L and <157-749 ng/L, respectively. The three studied factors were found to be statistically significant (95% confidence level) in removal of one or more hormones from soluble and/or total phase. MW hydrolysis of the influent resulted in both release (from sludge matrix) and attenuation of hormones in the soluble phase. Accumulation of estrone (E1) as well as progesterone (Pr) and androstenedione (Ad) in most of the digesters indicated possible microbial transformations among the hormones. Compared to controls, all pretreated digesters had lower total hormone concentrations in their influent streams. At 20 days SRT, highest total removal (E1+E2+Ad +Pr) was observed for the thermophilic control digester (56%), followed by pretreated mesophilic digesters at 120 °C and 160 °C with around 48% efficiency. In terms of conventional performance parameters, relative (to control) improvements of MW pretreated digesters at a 5-d SRT ranged in 98-163% and 57-121%, for volatile solids removal and methane production, respectively. PMID:23866136

  17. Evaluation of thermophilic anaerobic digestion processes for full-scale Class A biosolids disinfection at Hyperion Treatment Plant.

    PubMed

    Iranpour, R; Cox, H H J

    2007-05-01

    This paper describes 5 phases of full-scale testing at the City of Los Angeles Hyperion Treatment Plant (HTP) for producing Class A biosolids (U.S. EPA Part 503 Biosolids Rule) by thermophilic anaerobic digestion. Phases I and II were tests with a two-stage continuous-batch process in a thermophilic battery of six digesters and a designated post-digestion train that was isolated from mesophilic operations. These tests demonstrated that digester outflow biosolids met the Class A limits for fecal coliforms and Salmonella sp. However, fecal coliform densities sharply increased during post-digestion. The recurrence was possibly related to a combination of a large drop of the biosolids temperature after the dewatering centrifuges and contamination of thermophilically digested biosolids from mesophilic operations. Phase III was conducted after insulation and electrical heat-tracing of the post-digestion train to maintain a biosolids temperature throughout post-digestion at about the same level as in the digester outflow. Biosolids monitoring at the last points of plant control (silos at Truck Loading Facility and farm for land application) indicated that fecal coliform recurrence was prevented. After completing the conversion of HTP to thermophilic operation, certification tests of Phases IV and V demonstrated Class A compliance of a two-stage continuous-batch process under Alternatives 1 and 3 of the Part 503 Biosolids Rule, respectively. HTP received the permit for Class A (indeed exceptional quality) biosolids land application in Kern County, California, in December 2002 under Alternative 3. Since 2003, HTP has consistently complied with the federal and local standards for Class A biosolids, indicating that Class A limits can be met under conditions less stringent than defined by the Alternative 1 time-temperature requirement for batch treatment. PMID:17054113

  18. The conversion of anaerobic digestion waste into biofuels via a novel Thermo-Catalytic Reforming process.

    PubMed

    Neumann, Johannes; Meyer, Johannes; Ouadi, Miloud; Apfelbacher, Andreas; Binder, Samir; Hornung, Andreas

    2016-01-01

    Producing energy from biomass and other organic waste residues is essential for sustainable development. Fraunhofer UMSICHT has developed a novel reactor which introduces the Thermo-Catalytic Reforming (TCR®) process. The TCR® is a process which can convert any type of biomass and organic feedstocks into a variety of energy products (char, bio-oil and permanent gases). The aim of this work was to demonstrate this technology using digestate as the feedstock and to quantify the results from the post reforming step. The temperature of a post reformer was varied to achieve optimised fuel products. The hydrogen rich permanent gases produced were maximised at a post reforming temperature of 1023 K. The highly de-oxygenated liquid bio-oil produced contained a calorific value of 35.2 MJ/kg, with significantly improved fuel physical properties, low viscosity and acid number. Overall digestate showed a high potential as feedstock in the Thermo-Catalytic Reforming to produce pyrolysis fuel products of superior quality.

  19. The conversion of anaerobic digestion waste into biofuels via a novel Thermo-Catalytic Reforming process.

    PubMed

    Neumann, Johannes; Meyer, Johannes; Ouadi, Miloud; Apfelbacher, Andreas; Binder, Samir; Hornung, Andreas

    2016-01-01

    Producing energy from biomass and other organic waste residues is essential for sustainable development. Fraunhofer UMSICHT has developed a novel reactor which introduces the Thermo-Catalytic Reforming (TCR®) process. The TCR® is a process which can convert any type of biomass and organic feedstocks into a variety of energy products (char, bio-oil and permanent gases). The aim of this work was to demonstrate this technology using digestate as the feedstock and to quantify the results from the post reforming step. The temperature of a post reformer was varied to achieve optimised fuel products. The hydrogen rich permanent gases produced were maximised at a post reforming temperature of 1023 K. The highly de-oxygenated liquid bio-oil produced contained a calorific value of 35.2 MJ/kg, with significantly improved fuel physical properties, low viscosity and acid number. Overall digestate showed a high potential as feedstock in the Thermo-Catalytic Reforming to produce pyrolysis fuel products of superior quality. PMID:26190827

  20. Anaerobic prosthetic joint infection.

    PubMed

    Shah, Neel B; Tande, Aaron J; Patel, Robin; Berbari, Elie F

    2015-12-01

    In an effort to improve mobility and alleviate pain from degenerative and connective tissue joint disease, an increasing number of individuals are undergoing prosthetic joint replacement in the United States. Joint replacement is a highly effective intervention, resulting in improved quality of life and increased independence [1]. By 2030, it is predicted that approximately 4 million total hip and knee arthroplasties will be performed yearly in the United States [2]. One of the major complications associated with this procedure is prosthetic joint infection (PJI), occurring at a rate of 1-2% [3-7]. In 2011, the Musculoskeletal Infectious Society created a unifying definition for prosthetic joint infection [8]. The following year, the Infectious Disease Society of America published practice guidelines that focused on the diagnosis and management of PJI. These guidelines focused on the management of commonly encountered organisms associated with PJI, including staphylococci, streptococci and select aerobic Gram-negative bacteria. However, with the exception of Propionibacterium acnes, management of other anaerobic organisms was not addressed in these guidelines [1]. Although making up approximately 3-6% of PJI [9,10], anaerobic microorganisms cause devastating complications, and similar to the more common organisms associated with PJI, these bacteria also result in significant morbidity, poor outcomes and increased health-care costs. Data on diagnosis and management of anaerobic PJI is mostly derived from case reports, along with a few cohort studies [3]. There is a paucity of published data outlining factors associated with risks, diagnosis and management of anaerobic PJI. We therefore reviewed available literature on anaerobic PJI by systematically searching the PubMed database, and collected data from secondary searches to determine information on pathogenesis, demographic data, clinical features, diagnosis and management. We focused our search on five commonly

  1. Developments of anaerobic treatment

    SciTech Connect

    Roy, D.; Jones, L.M.

    1984-01-01

    Two modifications of anaerobic fermentation of biomass were studied: separation of acid and CH4 phases of the anaerobic process used in CH4 production from the biomass and the use of attached growth methanogenesis. A continuously stirred tank reactor (CSTR) was used for the acid phase. Effluent from the acid reactor was fed simultaneously to a conventional CSTR and an anaerobic rotating biological contactor (ARBC) operating in parallel for the CH4 phase. The temperature of all the reactors was 35 plus or minus 1 degree, the pH of the acid phase was 4.3, and the CH4 phase was studied at pH 7.5. The retention time for the acid phase CSTR was 4.5 h, and that for the ARBC and CSTR in the CH4 phase was 36 h.

  2. Differential sensitivities of the growth of Escherichia coli to acrylate under aerobic and anaerobic conditions and its effect on product formation.

    PubMed

    Arya, Ajay S; Lee, Sarah A; Eiteman, Mark A

    2013-11-01

    The effect of acrylate on the growth of Escherichia coli was determined under aerobic and anaerobic conditions in glucose-defined medium. Growth occurred with up to 35 mM acrylate under aerobic conditions but ceased at 5 mM acrylate under anaerobic conditions. This differential sensitivity can be attributed to inhibition of pyruvate formate lyase and/or pflB gene repression, as this enzyme is necessary for anaerobic growth of E. coli. The effect of acrylate on end-product distribution was also determined by growing E. coli first aerobically, then switching to anaerobic conditions. In the absence of acrylate, E. coli generated the typical distribution of mixed-acid products, with about 12 % of pyruvate being metabolically converted to lactate. In contrast, in the presence of 5 mM acrylate, E. coli converted 83 % of pyruvate to lactate, consistent with a reduction in pyruvate formate lyase activity.

  3. Ammonia stripping, activated carbon adsorption and anaerobic biological oxidation as process combination for the treatment of oil shale wastewater.

    PubMed

    Alexandre, Verônica M F; do Nascimento, Felipe V; Cammarota, Magali C

    2016-10-01

    Anaerobic biodegradability of oil shale wastewater was investigated after the following pretreatment sequence: ammonia stripping and activated carbon adsorption. Anaerobic biological treatment of oil shale wastewater is technically feasible after stripping at pH 11 for reducing the N-NH3 concentration, adsorption with 5 g/L of activated carbon in order to reduce recalcitrance and pH adjustment with CO2 so that the sulphate concentration in the medium remains low. After this pretreatment sequence, it was possible to submit the wastewater without dilution to an anaerobic treatment with 62.7% soluble chemical oxygen demand removal and specific methane production of 233.2 mL CH4STP/g CODremoved.

  4. Anaerobic/aerobic treatment of a petrochemical wastewater from two aromatic transformation processes by fluidized bed reactors.

    PubMed

    Estrada-Arriaga, Edson B; Ramirez-Camperos, Esperanza; Moeller-Chavez, Gabriela E; García-Sanchez, Liliana

    2012-01-01

    An integrated fluidized bed reactor (FBR) has been employed as the treatment for petrochemical industry wastewaters with high organic matter and aromatic compounds, under anaerobic and aerobic conditions. The system was operated at hydraulic residence time (HRT) of 2.7 and 2.2 h in the anaerobic and aerobic reactor, respectively. The degree of fluidization in the beds was 30%. This system showed a high performance on the removal of organic matter and aromatic compounds. At different organic loading rates (OLR), the chemical oxygen demand (COD) removal in the anaerobic reactor was close to 85% and removals of the COD up to 94% were obtained in the aerobic reactor. High removals of benzene, toluene, ethylbenzene, xylenes, styrene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene and naphthalene were achieved in this study. PMID:23109595

  5. The effects of temperature, organic matter and time-dependency on rheological properties of dry anaerobic digested swine manure.

    PubMed

    Liu, Gang-Jin; Liu, Yi; Wang, Zhi-Yong; Lei, Yun-Hui; Chen, Zi-Ai; Deng, Liang-Wei

    2015-04-01

    An efficient way to avoid the pollution of swine wastewater is the application of dry anaerobic digestion, which needs rheological parameter for stirring and pipe designing. The rheological properties of this kind of sludge have been studied for many decades, yet their effects only solid concentration has been investigated widely. In this paper, the influences of temperature, organic and time-dependency on the efficiency of anaerobic digested swine manure were studied. The viscosity decreased with temperature arranged from 10 to 60 °C which caused increase in protein from 7.18 to 8.49 g/kg. 60 °C can make the digested swine manure with TS from 16.6% to 21.5% reach to the same rheology state. The added peptone decreased the viscosity because of its function of water-reducing admixture and air entraining mixture. Time-dependent experiment showed the decrease of shear stress over time. The first and the second yield stress of dry anaerobic digested swine manure were evaluated through time-dependent model.

  6. Effects of permafrost thaw on carbon emissions under aerobic and anaerobic environments in the Great Hing'an Mountains, China.

    PubMed

    Song, Changchun; Wang, Xianwei; Miao, Yuqing; Wang, Jiaoyue; Mao, Rong; Song, Yanyu

    2014-07-15

    The carbon (C) pool of permafrost peatland is very important for the global C cycle. Little is known about how permafrost thaw could influence C emissions in the Great Hing'an Mountains of China. Through aerobic and anaerobic incubation experiments, we studied the effects of permafrost thaw on CH4 and CO2 emissions. The rates of CH4 and CO2 emissions were measured at -10, 0 and 10°C. Although there were still C emissions below 0°C, rates of CH4 and CO2 emissions significantly increased with permafrost thaw under aerobic and anaerobic conditions. The C release under aerobic conditions was greater than under anaerobic conditions, suggesting that permafrost thaw and resulting soil environment change should be important influences on C emissions. However, CH4 stored in permafrost soils could affect accurate estimation of CH4 emissions from microbial degradation. Calculated Q10 values in the permafrost soils were significantly higher than values in active-layer soils under aerobic conditions. Our results highlight that permafrost soils have greater potential decomposability than soils of the active layer, and such carbon decomposition would be more responsive to the aerobic environment.

  7. The effects of temperature, organic matter and time-dependency on rheological properties of dry anaerobic digested swine manure.

    PubMed

    Liu, Gang-Jin; Liu, Yi; Wang, Zhi-Yong; Lei, Yun-Hui; Chen, Zi-Ai; Deng, Liang-Wei

    2015-04-01

    An efficient way to avoid the pollution of swine wastewater is the application of dry anaerobic digestion, which needs rheological parameter for stirring and pipe designing. The rheological properties of this kind of sludge have been studied for many decades, yet their effects only solid concentration has been investigated widely. In this paper, the influences of temperature, organic and time-dependency on the efficiency of anaerobic digested swine manure were studied. The viscosity decreased with temperature arranged from 10 to 60 °C which caused increase in protein from 7.18 to 8.49 g/kg. 60 °C can make the digested swine manure with TS from 16.6% to 21.5% reach to the same rheology state. The added peptone decreased the viscosity because of its function of water-reducing admixture and air entraining mixture. Time-dependent experiment showed the decrease of shear stress over time. The first and the second yield stress of dry anaerobic digested swine manure were evaluated through time-dependent model. PMID:25616554

  8. Effect of L-ornithine hydrochloride ingestion on intermittent maximal anaerobic cycle ergometer performance and fatigue recovery after exercise.

    PubMed

    Demura, Shinichi; Morishita, Koji; Yamada, Takayoshi; Yamaji, Shunsuke; Komatsu, Miho

    2011-11-01

    L-Ornithine plays an important role in ammonia metabolism via the urea cycle. This study aimed to examine the effect of L-ornithine hydrochloride ingestion on ammonia metabolism and performance after intermittent maximal anaerobic cycle ergometer exercise. Ten healthy young adults (age, 23.8 ± 3.9 year; height, 172.3 ± 5.5 cm; body mass, 67.7 ± 6.1 kg) with regular training experience ingested L-ornithine hydrochloride (0.1 g/kg, body mass) or placebo after 30 s of maximal cycling exercise. Five sets of the same maximal cycling exercise were conducted 60 min after ingestion, and maximal cycling exercise was conducted after a 15 min rest. The intensity of cycling exercise was based on each subject's body mass (0.74 N kg(-1)). Work volume (watt), peak rpm (rpm) before and after intermittent maximal ergometer exercise and the following serum parameters were measured before ingestion, immediately after exercise and 15 min after exercise: ornithine, ammonia, urea, lactic acid and glutamate. Peak rpm was significantly greater with L-ornithine hydrochloride ingestion than with placebo ingestion. Serum ornithine level was significantly greater with L-ornithine hydrochloride ingestion than with placebo ingestion immediately and 15 min after intermittent maximal cycle ergometer exercise. In conclusion, although maximal anaerobic performance may be improved by L-ornithine hydrochloride ingestion before intermittent maximal anaerobic cycle ergometer exercise, the above may not depend on increase of ammonia metabolism with L-ornithine hydrochloride.

  9. Combination of extremum-seeking algorithms with effective hydraulic handling of equalization tanks to control anaerobic digesters.

    PubMed

    Alferes, J; Irizar, I

    2010-01-01

    The benefits of upgrading extremum-seeking controllers with an effective exploitation of the buffer capacity of equalization tanks have been investigated and applied to anaerobic digesters. In this respect, a Fuzzy-based supervisory module that monitors the state of the equalization tank has been designed and built on top of an extremum-seeking algorithm in charge of automatically regulating the wastewater fed into the anaerobic digester. The extremum-seeking controller guarantees good disturbance rejection and methane production around an upper limit set-point. The on-top Fuzzy module optimizes the long-term methane production by modifying this upper limit set-point as a function of the state of the equalization tank. A systematic simulation study has been carried out to evaluate the performance of the proposed control solution. Thus, on the basis of existing simulation benchmarks for assessment of control strategies in wastewater treatment plants, a dedicated simulation protocol for anaerobic digesters has been defined and implemented. Simulation results have shown that, compared with manual operation, effluent quality and methane production improvements of 10-15% are achieved using the proposed control approach. PMID:20489255

  10. Effects of different doses of caffeine on anaerobic exercise in boys.

    PubMed

    Turley, Ken; Eusse, Paola A; Thomas, Myles M; Townsend, Jeremy R; Morton, Aaron B

    2015-02-01

    This study investigated effects of low (1 mg·kg-1), moderate (3 mg·kg-1) and high (5 mg·kg-1) doses of caffeine on anaerobic performance in boys. Twenty-six 8- to 10-year-old boys participated in a double-blind, crossover, counter-balanced study. Boys received in random order a placebo (PL) or anhydrous caffeine: 1 (CAF-1), 3 (CAF-3), or 5 (CAF-5) mg caffeine·kg-1 body mass in cherry flavored Sprite. Sixty minutes following consumption boys performed a static handgrip test and then a 30-s Wingate test. Maximal grip strength (21.5 ± 4.9 & 21.6 ± 4.7 vs. 20.4 ± 4.0 kg) was significantly higher in CAF-5 & CAF-3 vs PL, respectively. Absolute and relative peak power (287 ± 72 vs 281 ± 69 W & 8.0 ± 0.9 vs 7.8 ± 1.0 W·kg-1) were significantly higher in CAF-3 vs PL, respectively. Mean power (153 ± 48 vs 146 ± 43 W) was significantly higher in CAF-5 vs PL, respectively. Peak Wingate HR was significantly higher (189 ± 8 vs 185 ± 9 beats·min-1) in CAF-5 vs PL, respectively. These findings suggest that in boys CAF-1 did not affect performance. During the Wingate test CAF-3 resulted in higher peak power while CAF-5 increased mean power. The significant increase in peak HR following the Wingate test is likely related to greater mean power generated during CAF-5. PMID:25051124

  11. Effects of different doses of caffeine on anaerobic exercise in boys.

    PubMed

    Turley, Ken; Eusse, Paola A; Thomas, Myles M; Townsend, Jeremy R; Morton, Aaron B

    2015-02-01

    This study investigated effects of low (1 mg·kg-1), moderate (3 mg·kg-1) and high (5 mg·kg-1) doses of caffeine on anaerobic performance in boys. Twenty-six 8- to 10-year-old boys participated in a double-blind, crossover, counter-balanced study. Boys received in random order a placebo (PL) or anhydrous caffeine: 1 (CAF-1), 3 (CAF-3), or 5 (CAF-5) mg caffeine·kg-1 body mass in cherry flavored Sprite. Sixty minutes following consumption boys performed a static handgrip test and then a 30-s Wingate test. Maximal grip strength (21.5 ± 4.9 & 21.6 ± 4.7 vs. 20.4 ± 4.0 kg) was significantly higher in CAF-5 & CAF-3 vs PL, respectively. Absolute and relative peak power (287 ± 72 vs 281 ± 69 W & 8.0 ± 0.9 vs 7.8 ± 1.0 W·kg-1) were significantly higher in CAF-3 vs PL, respectively. Mean power (153 ± 48 vs 146 ± 43 W) was significantly higher in CAF-5 vs PL, respectively. Peak Wingate HR was significantly higher (189 ± 8 vs 185 ± 9 beats·min-1) in CAF-5 vs PL, respectively. These findings suggest that in boys CAF-1 did not affect performance. During the Wingate test CAF-3 resulted in higher peak power while CAF-5 increased mean power. The significant increase in peak HR following the Wingate test is likely related to greater mean power generated during CAF-5.

  12. Separation of swine wastewater into different concentration fractions and its contribution to combined anaerobic-aerobic process.

    PubMed

    Yang, Di; Deng, Liangwei; Zheng, Dan; Wang, Lan; Liu, Yi

    2016-03-01

    There are two problems associated with treatment of swine wastewater, low efficiency of anaerobic digestion during winter and poor performance for aerobic treatment of digested effluent. A strategy employing unbalanced distributions of the pollutant mass and wastewater volumes in anaerobic and aerobic units was proposed. To accomplish this, swine wastewater was separated into high content liquid (HCL) and low content liquid (LCL). Three separation ratios of HCL to LCL (v/v), 1:9 (S1), 2:8 (S2), and 3:7 (S3), were evaluated. Anaerobically digestion of the HCL accounted for only 10%, 20% and 30% of the total volume of raw wastewater, but produced 63.38%, 73.79% and 76.61% of the total methane output for S1, S2 and S3, respectively. The mixed liquid of digested effluents of HCL and LCL were treated aerobically using sequencing batch reactors. S2 generated the best performance, with removal efficiencies of 96.98% for COD, 98.95% for NH3-N, 91.69% for TN and 74.71% for TP. The results obtained for S1 were not as good as those for S2, but were better than those for S3. Based on methane output from the anaerobic unit and pollutants removal in the aerobic unit, S2 was the most suitable system for the treatment of swine wastewater. Additionally, the anaerobic digestion efficiency of S2 was 282% higher than that of previous techniques employing balanced distribution. Taken together, these findings indicate that unbalanced distribution could improve the efficiency of the anaerobic unit remarkably, while ensuring good performance of the aerobic unit.

  13. Anaerobic soil disinfestation: Carbon rate effects on tomato plant growth and organic acid production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic soil disinfestation (ASD) is a non-chemical soil disinfestation technique proposed for the control of soil-borne pathogens, plant parasitic-nematodes, and weeds in different crops. ASD is applied in three steps: 1) Soil amendment with a labile carbon (C) source; 2) Cover the soil with tota...

  14. Menstrual Cycle Effects on Anaerobic Power, Muscular Strength, and Muscular Endurance in Trained and Untrained Females.

    ERIC Educational Resources Information Center

    Rosenburg, Beth S.; And Others

    A study determined if anaerobic power, isometric strength, and isometric endurance are affected by the menstrual cycle and if endurance trained females and untrained females are affected in the same manner on these performance parameters. Subjects were healthy, normally menstruating females, ages 18-34 years who were classified as either trained…

  15. Repeated sprint performance and metabolic recovery curves: effects of aerobic and anaerobic characteristics.

    PubMed

    de Aguiar, Rafael Alves; Turnes, Tiago; Santos de Oliveira Cruz, Rogério; Salvador, Amadeo Félix; Caputo, Fabrizio

    2015-05-01

    To examine the influence of aerobic and anaerobic indices on repeated sprint (RS) performance and ability (RSA), 8 sprinters (SPR), 8 endurance runners (END), and 8 active participants (ACT) performed the following tests: (i) incremental test; (ii) 1-min test to determine first decay time constant of pulmonary oxygen uptake off-kinetics and parameters related to anaerobic energy supply, lactate exchange, and removal abilities from blood lactate kinetics; and (iii) RS test (ten 35-m sprints, departing every 20 s) to determine best (RSbest) and mean (RSmean) sprint times and percentage of sprint decremen