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1

Methanogenesis in thermophilic biogas reactors  

Microsoft Academic Search

Methanogenesis in thermophilic biogas reactors fed with different wastes is examined. The specific methanogenic activity with acetate or hydrogen as substrate reflected the organic loading of the specific reactor examined. Increasing the loading of thermophilic reactors stabilized the process as indicated by a lower concentration of volatile fatty acids in the effluent from the reactors. The specific methanogenic activity in

Birgitte Kiær Ahring

1995-01-01

2

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

PubMed

This study investigated the potential of producing biogas on demand from maize silage using a novel two-phase continuously fed leach bed reactor (LBR) which is connected to an anaerobic filter (AF). Six different feeding patterns, each for 1week, were studied at a weekly average of a volatile solids (VS) loading rate of 4.5gL(-1)d(-1) and a temperature of 38°C. Methane production from the LBR and AF responded directly proportional to the VS load from the different daily feeding and resulted in an increase up to 50-60% per day, compared to constant feeding each day. The feeding patterns had no impact on VS methane yield which corresponded on average to 330Lkg(-1). In spite of some daily shock loadings, carried out during the different feeding patterns study, the reactor performance was not affected. A robust and reliable biogas production from stalky biomass was demonstrated. PMID:25479391

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

2015-02-01

3

Performance and microbial community analysis of the anaerobic reactor with coke oven gas biomethanation and in situ biogas upgrading.  

PubMed

A new method for simultaneous coke oven gas (COG) biomethanation and in situ biogas upgrading in anaerobic reactor was developed in this study. The simulated coke oven gas (SCOG) (92% H2 and 8% CO) was injected directly into the anaerobic reactor treating sewage sludge through hollow fiber membrane (HFM). With pH control at 8.0, the added H2 and CO were fully consumed and no negative effects on the anaerobic degradation of sewage sludge were observed. The maximum CH4 content in the biogas was 99%. The addition of SCOG resulted in enrichment and dominance of homoacetogenetic genus Treponema and hydrogenotrophic genus Methanoculleus in the liquid, which indicated that H2 were converted to methane by both direct (hydrogenotrophic methanogenesis) and indirect (homoacetogenesis+aceticlastic methanogenesis) pathways in the liquid. However, the aceticlasitic genus Methanosaeta was dominant for archaea in the biofilm on the HFM, which indicated indirect (homoacetogenesis+aceticlastic methanogenesis) H2 conversion pathway on the biofilm. PMID:23941705

Wang, Wen; Xie, Li; Luo, Gang; Zhou, Qi; Angelidaki, Irini

2013-10-01

4

Mesophilic syntrophic acetate oxidation during methane formation in biogas reactors  

Microsoft Academic Search

The reaction pathway for the formation of methane from acetate was investigated in sludge from 13 different biogas reactors. By following the conversion of [2-14C]acetate and [14C]bicarbonate it was shown that methane formation by syntrophic acetate oxidation was the dominating mechanism for acetotrophic methanogenesis in sludge containing high levels of salts, mainly ammonium, and volatile fatty acids. In one biogas

Anna Schnürer; Gerhard Zellner; Bo H. Svensson

1999-01-01

5

Anaerobic digestion of manure and mixture of manure with lipids: biogas reactor performance and microbial community analysis.  

PubMed

Anaerobic digestion of cattle manure and a mixture of cattle manure with glycerol trioleate (GTO) was studied in lab-scale, continuously stirred tank reactors (CSTR) operated at 37 degrees C. The reactor codigesting manure and lipids exhibited a significantly higher specific methane yield and a higher removal of VS than the reactor treating manure. Microbial population analysis done by cultivation--most probable number (MPN) test and specific methanogenic activity (SMA) measurement, revealed higher MPN and increased SMA of methanogenic populations of biomass from the reactor codigesting manure and lipids. Spatial microbial distribution and activity was studied in digested materials fractionated into size of particles > 200 microm, 50-200 microm and 0.45-50 microm. With manure, the main pool of methanogenic activity from propionate, butyrate and hydrogen was associated with the particles > 200 microm, while the activity of acetotrophic methanogens was uniformly distributed in all fractions. When digesting manure and lipids, an enhanced methanogenesis was detected both for particles > 200 microm and the 50-200 microm fraction. The molecular methods--temperature gradient gel electrophoresis (TGGE), cloning library and sequencing of 16S rDNA--showed presence of a restricted number of archaeal species in both reactors. The vast majority of clones was phylogenetically most closely related to Methanosarcina siciliae. PMID:14640228

Mladenovska, Z; Dabrowski, S; Ahring, B K

2003-01-01

6

Foam suppression in overloaded manure-based biogas reactors using antifoaming agents.  

PubMed

Foam control is an imperative need in biogas plants, as foaming is a major operational problem. In the present study, the effect of oils (rapeseed oil, oleic acid, and octanoic acid) and tributylphosphate on foam reduction and process performance in batch and continuous manure-based biogas reactors was investigated. The compounds were tested in dosages of 0.05%, 0.1% and 0.5% v/vfeed. The results showed that rapeseed oil was most efficient to suppress foam at the dosage of 0.05% and 0.1% v/vfeed, while octanoic acid was most efficient to suppress foam at dosage of 0.5% v/vfeed. Moreover, the addition of rapeseed oil also increased methane yield. In contrast, tributylphosphate, which was very efficient antifoam, was found to be inhibitory to the biogas process. PMID:24365741

Kougias, P G; Boe, K; Tsapekos, P; Angelidaki, I

2014-02-01

7

Ilchmann, Achim; Pahl, M. : Adaptive Multivariable pH Regulation of a Biogas Tower Reactor  

E-print Network

Ilchmann, Achim; Pahl, M. : Adaptive Multivariable pH Regulation of a Biogas Tower Reactor Zuerst. The adaptive controller was successlullytesteclover il pcriod of tu'o nonths at a biogas tower reuetoriu pilot are not applicable to the biogas tower reüctor.since a dontinatingf-eatureof the new reactol' prir-rciplc-is its

Knobloch,Jürgen

8

Microbial diversity and dynamicity of biogas reactors due to radical changes of feedstock composition.  

PubMed

The anaerobic digestion process is often inhibited by alteration of substrates and/or organic overload. This study aimed to elucidate changes of microbial ecology in biogas reactors upon radical changes of substrates and to determine their importance to process imbalance. For this reason, continuously fed reactors were disturbed with pulses of proteins, lipids and carbohydrates and the microbial ecology of the reactors were characterized by 16S rRNA gene sequencing before and after the imposed changes. The microbial composition of the three reactors, initially similar, diverged greatly after substrate change. The greatest increase in diversity was observed in the reactor supplemented with carbohydrates and the microbial community became dominated by lactobacilli, while the lowest corresponded to the reactor overfed with proteins, where only Desulfotomaculum showed significant increase. The overall results suggest that feed composition has a decisive impact on the microbial composition of the reactors, and thereby on their performance. PMID:25460984

De Francisci, Davide; Kougias, Panagiotis G; Treu, Laura; Campanaro, Stefano; Angelidaki, Irini

2015-01-01

9

Performance evaluation of Janata and Deenbandhu biogas plants  

SciTech Connect

Performance of the Janata and Deenbandhu fixed dome biogas plants for anaerobic digestion of dairy manure was evaluated under the conditions of a hilly region. In contrast to Janata, the Deenbandhu biogas plant was found to be not only cheaper on the basis of cost/m{sup 3} rated capacity of the plant, but it also produced more gas per unit of manure fed and per unit of digester volume in addition to maintaining a consistent rate of gas production during subsequent years from initial charging. The higher production of gas by 28.5% and 12.5% per kg of manure fed and 49.5% and 28.9% per m{sup 3} of digester volume was observed from this plant for highest 24 C and lowest 14 C digester temperatures of the plants for the months of July and December, respectively.

Kalia, A.K.; Kanwar, S.S. [H P Krishi Vishvavidyalaya, Palampur (India). Dept. of Agricultural Engineering

1996-04-01

10

Where does the removal of H?S from biogas occur in microaerobic reactors?  

PubMed

In order to maximise the efficiency of biogas desulphurisation and reduce the oxygen cost during microaerobic digestion, it is essential to know how the process occurs. For this purpose, a reactor with a total volume of 266 L, treating 10 L/d of sewage sludge, was operated with 25.0 L and without headspace. Under anaerobic conditions, the H2S concentration in the biogas varied between 0.21 and 0.38%v/v. Next, O2 was supplied from the bottom of the reactor. At 0.25-0.30 NLO?/Lfed, the biogas was entirely desulphurised, and its O? content remained below 1.03%v/v, when the digester had 25.0 L of gas space. However, with almost no headspace, the H2S content in the biogas fluctuated from 0.08 to 0.21%v/v, while the average O2 concentration was 1.66%v/v. The removed H2S accumulated in the outlet pipe of the biogas in the form of S(0) due to the insufficient headspace. PMID:24907574

Ramos, I; Peña, M; Fdz-Polanco, M

2014-08-01

11

Influence of Environmental Conditions on Methanogenic Compositions in Anaerobic Biogas Reactors  

Microsoft Academic Search

The influence of environmental parameters on the diversity of methanogenic communities in 15 full-scale biogas plants operating under different conditions with either manure or sludge as feedstock was studied. Fluorescence in situ hybridization was used to identify dominant methanogenic members of the Archaea in the reactor samples; enriched and pure cultures were used to support the in situ identification. Dominance

Dimitar Karakashev; Damien J. Batstone; Irini Angelidaki

2005-01-01

12

Unexpected Stability of Bacteroidetes and Firmicutes Communities in Laboratory Biogas Reactors Fed with Different Defined Substrates  

PubMed Central

In the present study, bacterial communities in 200-liter biogas reactors containing liquid manure consecutively fed with casein, starch, and cream were investigated over a period of up to 33 days. A 16S rRNA gene clone library identified Bacteroidetes and Firmicutes as the most abundant bacterial groups in the starting material, at 58.9% and 30.1% of sequences, respectively. The community development of both groups was monitored by real-time PCR and single-strand conformation polymorphism (SSCP) analysis. The Firmicutes and Bacteroidetes communities were unexpectedly stable and hardly influenced by batch-feeding events. The continuous feeding of starch led to community shifts that nevertheless contributed to a stable reactor performance. A longer starving period and a change in the pH value resulted in further community shifts within the Bacteroidetes but did not influence the Firmicutes. Predominant DNA bands from SSCP gels were cloned and sequenced. Sequences related to Peptococcaceae, Cytophagales, and Petrimonas sulfuriphila were found in all samples from all experiments. Real-time PCR demonstrated the abundance of members of the phylum Bacteroidetes and also reflected changes in gene copy numbers in conjunction with a changing pH value and acetate accumulation. PMID:22247168

Ratering, S.; Kramer, I.; Schmidt, M.; Zerr, W.; Schnell, S.

2012-01-01

13

Effect of hydrogen addition on the performance of a biogas fuelled spark ignition engine  

Microsoft Academic Search

Hydrogen was added in small amounts (5%, 10% and 15% on the energy basis) to biogas and tested in a spark ignition engine at constant speed at different equivalence ratios to study the effects on performance, emissions and combustion. Hydrogen significantly enhances the combustion rate and extends the lean limit of combustion of biogas. There is an improvement in brake

E. Porpatham; A. Ramesh; B. Nagalingam

2007-01-01

14

Inactivation of virus during anaerobic digestion of manure in laboratory scale biogas reactors  

Microsoft Academic Search

Reduction of porcine parvovirus, bovine enterovirus and faecal enterococci were measured in biogas reactors continuously run\\u000a on manure and manure supplemented with household waste at 35°C and 55°C and in batch test run at 70°C. The aim of the experiments\\u000a was to study the sanitation effect of anaerobic digestion and to evaluate the use of faecal enterococci as an indicator

Bente Lund; Vibeke Frøkjær Jensen; Per Have; Birgitte Ahring

1996-01-01

15

Microbial community analysis of a biogas-producing completely stirred tank reactor fed continuously with fodder beet silage as mono-substrate  

Microsoft Academic Search

The bioconversion of renewable raw material to biogas by anaerobic microbial fermentation processes in completely stirred tank reactors (CSTR) is a valuable alternative resource of energy especially for rural areas. However, knowledge about the microorganisms involved in the degradation of plant biomass is still poor. In this study, a first analysis of the biogas-forming process within a CSTR fed continuously

Michael Klocke; Pia Mähnert; Kerstin Mundt; Khadidja Souidi; Bernd Linke

2007-01-01

16

Experimental comparison of MCFC performance using three different biogas types and methane  

NASA Astrophysics Data System (ADS)

Biogas recovery is an environmentally friendly and cost-effective practice that is getting consensus in both the scientific and industrial community, as the growing number of projects demonstrate. The use of fuel cells as energy conversion systems increases the conversion efficiency, as well as the environmental benefits. Molten carbonate fuel cells (MCFC) operate at a temperature of about 650 °C, thus presenting a high fuel flexibility, compared to low temperature fuel cells. Aim of the present study is to compare the performance of an MCFC single cell, fuelled with different biogas types as well as methane. The biogases considered are derived from the following processes: (1) steam gasification in an entrained flow gasifier; (2) steam gasification in a duel interconnect fluidized bed gasifier; (3) biogas from an anaerobic digestion process. The performances are evaluated for different fuel utilization and current densities. The results are an essential starting point for a complete system design and demonstration.

Bove, Roberto; Lunghi, Piero

17

Guidebook on biogas development  

SciTech Connect

This guidebook covers the practical aspects of small-scale biogas development suitable for use in rural areas in developing countries, especially those of the ESCAP region. It is intended that all aspects of biogas are covered so that someone with no knowledge of the subject can, with confidence, design, build, operate and maintain a biogas plant. Information on biogas technology in China is also included. Chapters cover: the biogas process; factors effecting gas-plant design and operation; the classification and design principles of plants; design, size and site selection; the construction of digesters; gas holders and pipes; household gas appliances and their use; starting and operating a biogas digester; servicing and safety; improving gas-plant performance; commercial uses of biogas; the effluent and its uses, biogas-plant development programmes; community plants; and economics. In the annexes, designs for biogas plants of the fixed-dome, bag and floating gas-holder type are presented. 9 references.

Not Available

1980-01-01

18

Performance of a flameless combustion furnace using biogas and natural gas.  

PubMed

Flameless combustion technology has proved to be flexible regarding the utilization of conventional fuels. This flexibility is associated with the main characteristic of the combustion regime, which is the mixing of the reactants above the autoignition temperature of the fuel. Flameless combustion advantages when using conventional fuels are a proven fact. However, it is necessary to assess thermal equipments performance when utilizing bio-fuels, which usually are obtained from biomass gasification and the excreta of animals in bio-digesters. The effect of using biogas on the performance of an experimental furnace equipped with a self-regenerative Flameless burner is reported in this paper. All the results were compared to the performance of the system fueled with natural gas. Results showed that temperature field and uniformity are similar for both fuels; although biogas temperatures were slightly lower due to the larger amount of inert gases (CO(2)) in its composition that cool down the reactions. Species patterns and pollutant emissions showed similar trends and values for both fuels, and the energy balance for biogas showed a minor reduction of the efficiency of the furnace; this confirms that Flameless combustion is highly flexible to burn conventional and diluted fuels. Important modifications on the burner were not necessary to run the system using biogas. Additionally, in order to highlight the advantages of the Flameless combustion regime, some comparisons of the burner performance working in Flameless mode and working in conventional mode are presented. PMID:19944602

Colorado, A F; Herrera, B A; Amell, A A

2010-04-01

19

Clostridium bornimense sp. nov., isolated from a mesophilic, two-phase, laboratory-scale biogas reactor.  

PubMed

A novel anaerobic, mesophilic, hydrogen-producing bacterium, designated strain M2/40(T), was isolated from a mesophilic, two-phase, laboratory-scale biogas reactor fed continuously with maize silage supplemented with 5% wheat straw. 16S rRNA gene sequence comparison revealed an affiliation to the genus Clostridium sensu stricto (cluster I of the clostridia), with Clostridium cellulovorans as the closest characterized species, showing 93.8% sequence similarity to the type strain. Cells of strain M2/40(T) were rods to elongated filamentous rods that showed variable Gram staining. Optimal growth occurred at 35 °C and at pH 7. Grown on glucose, the main fermentation products were H2, CO2, formate, lactate and propionate. The DNA G+C content was 29.6 mol%. The major fatty acids (>10?%) were C(16?:?0), summed feature 10 (C(18?:?1)?11c/?9t/?6t and/or unknown ECL 17.834) and C(18?:?1)?11c dimethylacetal. Based on phenotypic, chemotaxonomic and phylogenetic differences, strain M2/40(T) represents a novel species within the genus Clostridium, for which we propose the name Clostridium bornimense sp. nov. The type strain is M2/40(T) (?=?DSM 25664(T)?=?CECT 8097(T)). PMID:24860110

Hahnke, Sarah; Striesow, Jutta; Elvert, Marcus; Mollar, Xavier Prieto; Klocke, Michael

2014-08-01

20

Model biogas steam reforming in a thin Pd-supported membrane reactor to generate clean hydrogen for fuel cells  

NASA Astrophysics Data System (ADS)

Steam reforming of a model biogas mixture is studied for generating clean hydrogen by using an inorganic membrane reactor, in which a composite Pd/Al2O3 membrane separates part of the produced hydrogen through its selective permeation. The characteristics of H2 perm-selectivity of the fresh membrane is expressed in terms of H2/N2 ideal selectivity, in this case equal to 4300. Concerning biogas steam reforming reaction, at 380 °C, 2.0 bar H2O:CH4 = 3:1, GHSV = 9000 h-1 the permeate purity of the recovered hydrogen is around 96%, although the conversion (15%) and hydrogen recovery (>20%) are relatively low; on the contrary, at 450 °C, 3.5 bar H2O:CH4 = 4:1, GHSV = 11000 h-1 the conversion is increased up to more than 30% and the recovery of hydrogen to about 70%. This novel work constitutes a reference study for new developments on biogas steam reforming reaction in membrane reactors.

Iulianelli, A.; Liguori, S.; Huang, Y.; Basile, A.

2015-01-01

21

Aerobic desulfurization of biogas by acidic biotrickling filtration in a randomly packed reactor.  

PubMed

Biotrickling filters for biogas desulfurization still must prove their stability and robustness in the long run under extreme conditions. Long-term desulfurization of high loads of H2S under acidic pH was studied in a lab-scale aerobic biotrickling filter packed with metallic Pall rings. Reference operating conditions at steady-state corresponded to an empty bed residence time (EBRT) of 130s, H2S loading rate of 52gS-H2Sm(-3)h(-1) and pH 2.50-2.75. The EBRT reduction showed that the critical EBRT was 75s and the maximum EC 100gS-H2Sm(-3)h(-1). Stepwise increases of the inlet H2S concentration up to 10,000 ppmv lead to a maximum EC of 220gS-H2Sm(-3)h(-1). The H2S removal profile along the filter bed indicated that the first third of the filter bed was responsible for 70-80% of the total H2S removal. The oxidation rate of solid sulfur accumulated inside the bioreactor during periodical H2S starvation episodes was verified under acidic operating conditions. The performance under acidic pH was comparable to that under neutral pH in terms of H2S removal capacity. However, bioleaching of the metallic packing used as support and chemical precipitation of sulfide/sulfur salts occurred. PMID:25151242

Montebello, Andrea M; Mora, Mabel; López, Luis R; Bezerra, Tercia; Gamisans, Xavier; Lafuente, Javier; Baeza, Mireia; Gabriel, David

2014-09-15

22

Neural-fuzzy control system application for monitoring process response and control of anaerobic hybrid reactor in wastewater treatment and biogas production.  

PubMed

Based on the developed neural-fuzzy control system for anaerobic hybrid reactor (AHR) in wastewater treatment and biogas production, the neural network with backpropagation algorithm for prediction of the variables pH, alkalinity (Alk) and total volatile acids (TVA) at present day time t was used as input data for the fuzzy logic to calculate the influent feed flow rate that was applied to control and monitor the process response at different operations in the initial, overload influent feeding and the recovery phases. In all three phases, this neural-fuzzy control system showed great potential to control AHR in high stability and performance and quick response. Although in the overloading operation phase II with two fold calculating influent flow rate together with a two fold organic loading rate (OLR), this control system had rapid response and was sensitive to the intended overload. When the influent feeding rate was followed by the calculation of control system in the initial operation phase I and the recovery operation phase III, it was found that the neural-fuzzy control system application was capable of controlling the AHR in a good manner with the pH close to 7, TVA/Alk < 0.4 and COD removal > 80% with biogas and methane yields at 0.45 and 0.30 m3/kg COD removed. PMID:21462705

Waewsak, Chaiwat; Nopharatana, Annop; Chaiprasert, Pawinee

2010-01-01

23

Assessment of energy performance in the life-cycle of biogas production  

Microsoft Academic Search

Energy balances are analysed from a life-cycle perspective for biogas systems based on 8 different raw materials. The analysis is based on published data and relates to Swedish conditions. The results show that the energy input into biogas systems (i.e. large-scale biogas plants) overall corresponds to 20–40% (on average approximately 30%) of the energy content in the biogas produced. The

Maria Berglund; Pål Börjesson

2006-01-01

24

Microbial community composition and dynamics in high-temperature biogas reactors using industrial bioethanol waste as substrate.  

PubMed

Stillage, which is generated during bioethanol production, constitutes a promising substrate for biogas production within the scope of an integrated biorefinery concept. In this study, a microbial community was grown on thin stillage as mono-substrate in a continuous stirred tank reactor (CSTR) at a constant temperature of 55 °C, at an organic loading rate of 1.5 goTS/L*d and a retention time of 25 days. Using an amplicon-based dataset of 17,400 high-quality sequences of 16S rRNA gene fragments (V2-V3 regions), predominance of Bacteria assigned to the families Thermotogaceae and Elusimicrobiaceae was detected. Dominant members of methane-producing Euryarchaeota within the CSTR belonged to obligate acetoclastic Methanosaetaceae and hydrogenotrophic Methanobacteriaceae. In order to investigate population dynamics during reactor acidification, the organic loading rate was increased abruptly, which resulted in an elevated concentration of volatile fatty acids. Acidification led to a decrease in relative abundance of Bacteria accompanied with stable numbers of Archaea. Nevertheless, the abundance of Methanosaetaceae increased while that of Methanobacteriales decreased successively. These findings demonstrate that a profound intervention to the biogas process may result in persistent community changes and reveals uncommon bacterial families as process-relevant microorganisms. PMID:25012784

Röske, Immo; Sabra, Wael; Nacke, Heiko; Daniel, Rolf; Zeng, An-Ping; Antranikian, Garabed; Sahm, Kerstin

2014-11-01

25

Thermal efficiency and environmental performances of a biogas-diesel stationary engine.  

PubMed

Municipal and agricultural waste, and sludge from wastewater treatment represent a large source of pollution. Gaseous fuels can be produced from waste decomposition and then used to run internal combustion engines for power and heat generation. The present paper focuses on thermal efficiency and environmental performances of dual-fuel engines fuelled with biogas. Experiments have been carried out on a Lister-Petter single cylinder diesel engine, modified for dual-fuel operation. Natural gas was first used as the primary fuel. An empirical correlation was determined to predict the engine load for a given mass flow rate for the pilot fuel (diesel) and for the primary fuel (natural gas). That correlation has then been tested for three synthesized biogas compositions. Computations were performed and the error was estimated to be less than 10%. Additionally, NOx and CO2 contents were measured from exhaust gases. Based on exhausts gas temperature, the activation energy and the pre-exponential factor of an Arrhenius law were then proposed, resulting in a simpler mean to predict NOx. PMID:14599150

Bilcan, A; Le Corre, O; Delebarre, A

2003-09-01

26

Continuous production of biogas from dairy manure using an innovative no-mix reactor  

Microsoft Academic Search

A 25 L no-mix anaerobic digester was designed and fabricated. The digester was designed to act as liquid-solid separator.\\u000a The sludges obtained from the bottom of the digester had high nitrogen and ash concentrations while the effluent had no offensive\\u000a odor. The performance of the no-mix digester was compared to that of a continuous stirred tank reactor at two temperatures

A. E. Ghaly; R. M. Ben-Hassan

1989-01-01

27

Utilization of high-strength wastewater for the production of biogas as a renewable energy source using hybrid upflow anaerobic sludge blanket (HUASB) reactor  

SciTech Connect

Anaerobic digestion of distillery spentwash, a high-strength wastewater, was studied using a hybrid upflow anaerobic sludge blanket (HUASB) reactor for 240 days under ambient conditions. The HUASB reactor combined an open volume in the bottom two-thirds of the reactor for sludge blanket and polypropylene pall rings packing in the upper one-third of the reactor. The aim of the study was to achieve optimum biogas production and waste treatment. Using non-granular anaerobic sewage sludge as seed, the start-up of the HUASB reactor was successfully completed, with the production of active bacterial granules of 1--2 mm size, within 90 days. Examination of the bacterial granules under scanning electron microscope (SEM) revealed that Methanothrix like microorganisms were the dominant species besides Methanosarcina. An organic loading of 24 kg COD/m{sup 3}d at a low hydraulic retention time (HRT) of 6 hours was achieved with 82% reduction in COD. Biogas with high methane content (80%) was produced at these loadings. The specific biogas yield was 0.36 m{sup 3} CH{sub 4}/kg COD. Packing in the upper third of the reactor was very efficient as a gas-solid separator (GSS); and in addition it retained the biomass.

Shivayogimath, C.B.; Ramanujam, T.K.

1998-07-01

28

Long-term stability of thermophilic co-digestion submerged anaerobic membrane reactor encountering high organic loading rate, persistent propionate and detectable hydrogen in biogas.  

PubMed

The performance of thermophilic anaerobic co-digestion of coffee grounds and sludge using membrane reactor was investigated for 148 days, out of a total research duration of 263 days. The OLR was increased from 2.2 to 33.7 kg-COD/m(3)d and HRT was shortened from 70 to 7 days. A significant irreversible drop in pH confirmed the overload of reactor. Under a moderately high OLR of 23.6 kg-COD/m(3)d, and with HRT and influent total solids of 10 days and 150 g/L, respectively, the COD removal efficiency was 44.5%. Hydrogen in biogas was around 100-200 ppm, which resulted in the persistent propionate of 1.0-3.2g/L. The VFA consumed approximately 60% of the total alkalinity. NH4HCO3 was supplemented to maintain alkalinity. The stability of system relied on pH management under steady state. The 16SrDNA results showed that hydrogen-utilizing methanogens dominates the archaeal community. The propionate-oxidizing bacteria in bacterial community was insufficient. PMID:24090872

Qiao, Wei; Takayanagi, Kazuyuki; Niu, Qigui; Shofie, Mohammad; Li, Yu You

2013-12-01

29

Updated guidebook on biogas development  

SciTech Connect

On the practical aspects of small-scale biogas development suitable for use in rural areas of developing countries reviews biogas development throughout the ESCAP region and examines each of the steps involved in developing and operating a biogas plant. It details both the process and the microbiology of biogas fermentation and analyses the factors affecting gas plant design and operation. Also covered are the classification and design principles of plants, design, site, and site selection; starting and operating a gas plant; servicing and safety; and efficient plant performance. Also considered are the commercial uses of biogas and possible use of effluent.

Not Available

1985-01-01

30

Detailed analysis of metagenome datasets obtained from biogas-producing microbial communities residing in biogas reactors does not indicate the presence of putative pathogenic microorganisms  

PubMed Central

Background In recent years biogas plants in Germany have been supposed to be involved in amplification and dissemination of pathogenic bacteria causing severe infections in humans and animals. In particular, biogas plants are discussed to contribute to the spreading of Escherichia coli infections in humans or chronic botulism in cattle caused by Clostridium botulinum. Metagenome datasets of microbial communities from an agricultural biogas plant as well as from anaerobic lab-scale digesters operating at different temperatures and conditions were analyzed for the presence of putative pathogenic bacteria and virulence determinants by various bioinformatic approaches. Results All datasets featured a low abundance of reads that were taxonomically assigned to the genus Escherichia or further selected genera comprising pathogenic species. Higher numbers of reads were taxonomically assigned to the genus Clostridium. However, only very few sequences were predicted to originate from pathogenic clostridial species. Moreover, mapping of metagenome reads to complete genome sequences of selected pathogenic bacteria revealed that not the pathogenic species itself, but only species that are more or less related to pathogenic ones are present in the fermentation samples analyzed. Likewise, known virulence determinants could hardly be detected. Only a marginal number of reads showed similarity to sequences described in the Microbial Virulence Database MvirDB such as those encoding protein toxins, virulence proteins or antibiotic resistance determinants. Conclusions Findings of this first study of metagenomic sequence reads of biogas producing microbial communities suggest that the risk of dissemination of pathogenic bacteria by application of digestates from biogas fermentations as fertilizers is low, because obtained results do not indicate the presence of putative pathogenic microorganisms in the samples analyzed. PMID:23557021

2013-01-01

31

Biogas utilization  

SciTech Connect

Options for successfully using biogas depend on project scale. Almost all biogas from anaerobic digesters must first go through a gas handling system that pressurizes, meters, and filters the biogas. Additional treatment, including hydrogen sulfide-mercaptan scrubbing, gas drying, and carbon dioxide removal may be necessary for specialized uses, but these are complex and expensive processes. Thus, they can be justified only for large-scale projects that require high-quality biogas. Small-scale projects (less than 65 cfm) generally use biogas (as produced) as a boiler fuel or for fueling internal combustion engine-generators to produce electricity. If engines or boilers are selected properly, there should be no need to remove hydrogen sulfide. Small-scale combustion turbines, steam turbines, and fuel cells are not used because of their technical complexity and high capital cost. Biogas cleanup to pipeline or transportation fuel specifications is very costly, and energy economics preclude this level of treatment.

Moser, M.A. [Resource Conservation Management, Inc., Berkeley, CA (United States)

1996-01-01

32

Low-temperature upgrading of low-calorific biogas for CO2 mitigation using DBD-catalyst hybrid reactor  

NASA Astrophysics Data System (ADS)

Although huge amounts of biogas, which consists of 20-60% of CH4 in CO2/N2, can be obtained from landfills, coal mines, and agricultural residues, most of them are simply flared and wasted: because global warming potential of biogas is 5-15 times as potent as CO2. Poor combustibility of such biogas makes it difficult to utilize in conventional energy system. The purpose of this project is to promote the profitable recovery of methane from poor biogas via non-thermal plasma technology. We propose low-temperature steam reforming of biogas using DBD generated in catalyst beds. Methane is partially converted into hydrogen, and then fed into internal combustion engines for improved ignition stability as well as efficient operation. Low-temperature steam reforming is beneficial because exhaust gas from an engine can be used to activate catalyst beds. Space velocity (3600-15000 hr-1), reaction temperature (300-650^oC), and energy cost (30-150 kJ per mol CH4) have been investigated with simulated biogas (20-60% CH4 in mixtures of CO2/N2). The DBD enhances reaction rate of CH4 by a factor of ten at given catalyst temperatures, which is a rate-determining step of methane steam reforming, while species concentration of upgraded biogas was governed by thermodynamic equilibrium in the presence of catalyst.

Nozaki, Tomohiro; Tsukijihara, Hiroyuki; Fukui, Wataru; Okazaki, Ken

2006-10-01

33

Biogas utilization  

SciTech Connect

Options for successfully using biomass depend on project scale. Almost all biogas from anaerobic digesters must first go through a gas handling system that pressurizes, meters, and filters the biogas. Additional treatment, including hydrogen sulfide-mercaptan scrubbing, gas drying, and carbon dioxide removal may be necessary for specialized uses, but these are complex and expensive processes. Thus, they can be justified only for large-scale projects that require high-quality biogas. Small-scale projects (less than 65 cfm) generally use biogas (as produced) as a boiler fuel or for fueling internal combustion engine generators to produce electricity. If engines or boilers as selected properly, there should be no need to remove hydrogen sulfide. Small-scale combustion turbines, steam turbines, and fuel cells are not used because of their technical complexity and high capital cost. Biogas cleanup to pipeline or transportation fuel specification is very costly, and energy economics preclude this level of treatment.

Moser, M.A. [Resource Conservation Management, Inc., Berkeley, CA (United States)

1995-11-01

34

Effect of compression ratio on the performance and combustion of a biogas fuelled spark ignition engine  

Microsoft Academic Search

A single cylinder diesel engine was modified to operate as a biogas operated spark ignition engine. The engine was operated at 1500 rpm at throttle opening of 25% and 100% at various equivalence ratios. The tests were covered a range of equivalence ratios from rich to the lean operating limit and a number of compression ratios. The spark timing was

E. Porpatham; A. Ramesh; B. Nagalingam

35

Improvement of Biogas Production by Bioaugmentation  

PubMed Central

Biogas production technologies commonly involve the use of natural anaerobic consortia of microbes. The objective of this study was to elucidate the importance of hydrogen in this complex microbial food chain. Novel laboratory biogas reactor prototypes were designed and constructed. The fates of pure hydrogen-producing cultures of Caldicellulosiruptor saccharolyticus and Enterobacter cloacae were followed in time in thermophilic and mesophilic natural biogas-producing communities, respectively. Molecular biological techniques were applied to study the altered ecosystems. A systematic study in 5-litre CSTR digesters revealed that a key fermentation parameter in the maintenance of an altered population balance is the loading rate of total organic solids. Intensification of the biogas production was observed and the results corroborate that the enhanced biogas productivity is associated with the increased abundance of the hydrogen producers. Fermentation parameters did not indicate signs of failure in the biogas production process. Rational construction of more efficient and sustainable biogas-producing microbial consortia is proposed. PMID:23484123

Kovács, K. L.; Ács, N.; Kovács, E.; Wirth, R.; Rákhely, G.; Strang, Orsolya; Herbel, Zsófia; Bagi, Z.

2013-01-01

36

Effects of reactor configuration on the performance of static-bed submerged media anaerobic reactors  

SciTech Connect

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.

Chiang, C.F.

1988-01-01

37

Performance evaluation of a completely stirred anaerobic reactor treating pig manure at a low range of mesophilic conditions  

SciTech Connect

Highlights: • The biogas process can run stably at 20 °C at extremely low OLR after long-term acclimation of bacteria. • A biogas plant running at 28 °C seems as efficient as that operated at 38 °C at low OLR of 1.3 g ODM L{sup ?1} d{sup ?1}. • Lower temperature operation is inadvisable for the commercial biogas plant running at rather high OLR. • The estimated sludge yield at 28 °C is higher than that at 38 °C. - Abstract: Many Chinese biogas plants run in the lower range of mesophilic conditions. This study evaluated the performance of a completely stirred anaerobic reactor treating pig manure at different temperatures (20, 28 and 38 °C). The start-up phase of the reactor at 20 °C was very long and extremely poor performance was observed with increasing organic loading rate (OLR). At an OLR of 4.3 g ODM L{sup ?1} d{sup ?1}, methane production at 28 °C was comparable (3% less) with that at 38 °C, but the risk of acidification was high at 28 °C. At low OLR (1.3 g ODM L{sup ?1} d{sup ?1}), the biogas process appeared stable at 28 °C and gave same methane yields as compared to the reactor operating at 38 °C. The estimated sludge yield at 28 °C was 0.065 g VSS g{sup ?1} COD{sub removed,} which was higher than that at 38 °C (0.016 g VSS g{sup ?1} COD{sub removed})

Guo, Jianbin, E-mail: jianbinguo@gmail.com [Department of Environmental Engineering, Tsinghua University, Beijing 100084 (China); Dong, Renjie [College of Engineering, China Agricultural University, P.O. Box 184, Beijing 100083 (China); Clemens, Joachim [Institute of Crop Science and Resource Reservation (INRES), University of Bonn, Karlrobert-Kreiten-Strasse 13, 53115 Bonn (Germany); Wang, Wei [Department of Environmental Engineering, Tsinghua University, Beijing 100084 (China)

2013-11-15

38

Performance of anaerobic sequencing batch reactor in the treatment of pharmaceutical wastewater containing erythromycin and sulfamethoxazole mixture.  

PubMed

This study evaluates the joint effects of erythromycin-sulfamethoxazole (ES) combinations on anaerobic treatment efficiency and the potential for antibiotic degradation during anaerobic sequencing batch reactor operation. The experiments involved two identical anaerobic sequencing batch reactors. One reactor, as control unit, was fed with synthetic wastewater while the other reactor (ES) was fed with a synthetic substrate mixture including ES antibiotic combinations. The influence of ES antibiotic mixtures on chemical oxygen demand (COD) removal, volatile fatty acid production, antibiotic degradation, biogas production, and composition were investigated. The influent antibiotic concentration was gradually increased over 10 stages, until the metabolic collapse of the reactors, which occurred at 360 days for the ES reactor. The results suggest that substrate/COD utilization and biogas/methane generation affect performance of the anaerobic reactors at higher concentration. In addition, an average of 40% erythromycin and 37% sulfamethoxazole reduction was achieved in the ES reactor. These results indicated that these antibiotics were partly biodegradable in the anaerobic reactor system. PMID:25429450

Aydin, S; Ince, B; Cetecioglu, Z; Ozbayram, E G; Shahi, A; Okay, O; Arikan, O; Ince, O

2014-01-01

39

Biogas in France  

SciTech Connect

Biogas is produced by the methanation of organic matter. It involves a process of fermentation carried out in an air-free environment by populations of bacteria living in symbiosis. The methane content of biogas is high (50 - 80%) and it constitutes an advantageous solution to the problems of energy supply in developing countries and in rural zones where natural gas is not distributed. Everywhere, methanation contributes to the control of environmental pollution, and biogas production is sometimes accompanied by the output of high quality fertilizer. Over the last few years, France has engaged in a certain number of research projects for the development of high performance techniques in the field of biogas, and the gas industry has made a considerable contribution in the setting up of a certain number of installations. The researchers and manufacturers involved have therefore acquired wide experience in this domain. Solutions, original both in technical and economic terms, have been found, and they are henceforth available to all those countries who wish to produce and exploit biogas.

Donat, G.

1988-01-01

40

Janata biogas technology and fodder production  

SciTech Connect

An effective bio-gas program leads to efficient use of cow dung for gas recovery and partial supplement to plant nutrient requirements. Bio-gas program leads to improvement in rural living including rural sanitation. The Janata biogas plant designed by the State Planning Institute, Lucknow, based on biogas technology, has proved to be efficient and economical. This book contains the various papers presented at the seminar held to review this technology. The various topics covered are: Status of Biogas Program in India; Role of Extension Agencies in Developing Program of Energy Utilization; Introduction to Drumless Biogas Plant; Principles and Application of Anaerobic Fermentation and Biogas Production, Operational System of Gobar Gas in Rural India; Complete Recycling of Cattle Shed Wastes through Biogas Plant; Chemical Composition of Cattle Excreta and Its Manurial Value; Profitability of Biogas Plant; Biogas Production from Various Organic Wastes; Performance of Janata Biogas Plant and Biogas Utilization in Appliances; Utilization of Solar Energy for Domestic Purposes; and Conservation of Forages. Plant requirements and cost estimates have been given for several units.

Neelakantan, S.

1981-01-01

41

Harvesting biogas from wastewater sludge and food waste  

NASA Astrophysics Data System (ADS)

Wastewater sludge and food waste are good source of biogas. Anaerobic treatment of slude and food waste able to produce biogas which is a potential renewable energy source. This study looks into the potential biogas generation and the effects of temperature on biogas generation. A lab scale reactor was used to simulate the biogas generation. The results show that wastewater sludge able to produced upto 44.82 ml biogas/kg of sludge. When mixed with food waste at a ratio of 30:70 (food waste), the biogas generated were 219.07 ml/kg of waste. Anaerobic of food waste alone produced biogas amount to 59.75 ml/kg of food waste. Anaerobic treatment also reduces the volume of waste. The effect of temperature shows that higher temperature produces more biogas than lower temperature.

Chua, K. H.; Cheah, W. L.; Tan, C. F.; Leong, Y. P.

2013-06-01

42

Sustainable operation of submerged Anammox membrane bioreactor with recycling biogas sparging for alleviating membrane fouling.  

PubMed

A submerged anaerobic ammonium oxidizing (Anammox) membrane bioreactor with recycling biogas sparging for alleviating membrane fouling has been successfully operated for 100d. Based on the batch tests, a recycling biogas sparging rate at 0.2m(3)h(-1) was fixed as an ultimate value for the sustainable operation. The mixed liquor volatile suspended solid (VSS) of the inoculum for the long operation was around 3000mgL(-1). With recycling biogas sparging rate increasing stepwise from 0 to 0.2m(3)h(-1), the reactor reached an influent total nitrogen (TN) up to 1.7gL(-1), a stable TN removal efficiency of 83% and a maximum specific Anammox activity (SAA) of 0.56kg TNkg(-1) VSSd(-1). With recycling biogas sparging rate at 0.2 m(3) h(-1) (corresponding to an aeration intensity of 118m(3)m(-2)h(-1)), the membrane operation circle could prolong by around 20 times compared to that without gas sparging. Furthermore, mechanism of membrane fouling was proposed. And with recycling biogas sparging, the VSS and EPS content increasing rate in cake layer were far less than the ones without biogas sparging. The TN removal performance and sustainable membrane operation of this system showed the appealing potential of the submerged Anammox MBR with recycling biogas sparging in treating high-strength nitrogen-containing wastewaters. PMID:25311769

Li, Ziyin; Xu, Xindi; Xu, Xiaochen; Yang, FengLin; Zhang, ShuShen

2014-10-10

43

Comparative life cycle assessment of biogas plant configurations for a demand oriented biogas supply for flexible power generation.  

PubMed

The environmental performance of biogas plant configurations for a demand - oriented biogas supply for flexible power generation is comparatively assessed in this study. Those configurations indicate an increased energy demand to operate the operational enhancements compared to conventional biogas plants supplying biogas for baseload power generation. However, findings show that in contrast to an alternative supply of power generators with natural gas, biogas supplied on demand by adapted biogas plant configurations saves greenhouse gas emissions by 54-65gCO2-eqMJ(-1) and primary energy by about 1.17MJMJ(-1). In this regard, configurations with flexible biogas production profit from reduced biogas storage requirements and achieve higher savings compared to configurations with continuous biogas production. Using thicker biogas storage sheeting material reduces the methane permeability of up to 6m(3)d(-1) which equals a reduction of 8% of the configuration's total methane emissions. PMID:25553565

Hahn, Henning; Hartmann, Kilian; Bühle, Lutz; Wachendorf, Michael

2015-03-01

44

Complete genome sequence of the novel Porphyromonadaceae bacterium strain ING2-E5B isolated from a mesophilic lab-scale biogas reactor.  

PubMed

In this study, the whole genome sequence of the mesophilic, anaerobic Porphyromonadaceae bacterium strain ING2-E5B (LMG 28429, DSM 28696) is reported. The new isolate belongs to the phylum Bacteroidetes and was obtained from a biogas-producing lab-scale completely stirred tank reactor (CSTR) optimized for anaerobic digestion of maize silage in co-fermentation with pig and cattle manure. The genome of strain ING2-E5B contains numerous genes encoding proteins and enzymes involved in the degradation of complex carbohydrates and proteinaceous compounds. Moreover, it possesses genes catalyzing the production of volatile fatty acids. Hence, this bacterium was predicted to be involved in hydrolysis and acidogenesis during anaerobic digestion and biomethanation. PMID:25444871

Hahnke, Sarah; Maus, Irena; Wibberg, Daniel; Tomazetto, Geizecler; Pühler, Alfred; Klocke, Michael; Schlüter, Andreas

2015-01-10

45

Fast Reactor Fuel Type and Reactor Safety Performance  

SciTech Connect

Fast Reactor Fuel Type and Reactor Safety Performance R. Wigeland , Idaho National Laboratory J. Cahalan, Argonne National Laboratory The sodium-cooled fast neutron reactor is currently being evaluated for the efficient transmutation of the highly-hazardous, long-lived, transuranic elements that are present in spent nuclear fuel. One of the fundamental choices that will be made is the selection of the fuel type for the fast reactor, whether oxide, metal, carbide, nitride, etc. It is likely that a decision on the fuel type will need to be made before many of the related technologies and facilities can be selected, from fuel fabrication to spent fuel reprocessing. A decision on fuel type should consider all impacts on the fast reactor system, including safety. Past work has demonstrated that the choice of fuel type may have a significant impact on the severity of consequences arising from accidents, especially for severe accidents of low probability. In this paper, the response of sodium-cooled fast reactors is discussed for both oxide and metal fuel types, highlighting the similarities and differences in reactor response and accident consequences. Any fast reactor facility must be designed to be able to successfully prevent, mitigate, or accommodate all consequences of potential events, including accidents. This is typically accomplished by using multiple barriers to the release of radiation, including the cladding on the fuel, the intact primary cooling system, and most visibly the reactor containment building. More recently, this has also included the use of ‘inherent safety’ concepts to reduce or eliminate the potential for serious damage in some cases. Past experience with oxide and metal fuel has demonstrated that both fuel types are suitable for use as fuel in a sodium-cooled fast reactor. However, safety analyses for these two fuel types have also shown that there can be substantial differences in accident consequences due to the neutronic and thermophysical properties of the fuel and their compatibility with the reactor coolant, with corresponding differences in the challenges presented to the reactor developers. Accident phenomena are discussed for the sodium-cooled fast reactor based on the mechanistic progression of conditions from accident initiation to accident termination, whether a benign state is achieved or more severe consequences are expected. General principles connecting accident phenomena and fuel properties are developed from the oxide and metal fuel safety analyses, providing guidelines that can be used as part of the evaluation for selection of fuel type for the sodium-cooled fast reactor.

R. Wigeland; J. Cahalan

2009-09-01

46

Evidence of anaerobic syntrophic acetate oxidation in biogas batch reactors by analysis of 13C carbon isotopes.  

PubMed

Between 2008 and 2010 various batch experiments were carried out to study the stable carbon isotopic composition of biogas (CH4 and CO2) produced from (i) pure sludge and (ii) sludge including maize. From the evolution of the natural isotopic signature, a temporal change of methanogenic pathways could be detected for the treatment with maize showing that a dominance in acetotrophic methanogenesis was replaced by a mixture of hydrogenotrophic and acetotrophic methanogenesis. For pure sludge, hydrogenotrophic methanogenesis was the dominant or probably exclusive pathway. Experiments with isotopically labelled acetate (99% (13)CH3COONa and 99% CH3(13)COONa) indicated a significant contribution of syntrophic acetate oxidation (SAO) for all the investigated treatments. In the case of pure sludge, experiments from 2008 showed that acetate was almost entirely oxidised to CO2, i.e. acetotrophic methanogenesis was negligible. However, in 2010, the sludge showed a clear dominance in acetotrophic methanogenesis with a minor contribution by SAO indicating a significant change in the metabolic character. Our results indicate that SAO during anaerobic degradation of maize might be a significant process that needs to be considered in biogas research. PMID:23781862

Polag, Daniela; Heuwinkel, Hauke; Laukenmann, Stephan; Greule, Markus; Keppler, Frank

2013-01-01

47

Quantification of syntrophic fatty acid-{beta}-oxidizing bacteria in a mesophilic biogas reactor by oligonucleotide probe hybridization  

SciTech Connect

Small-subunit rRNA sequences were obtained for two saturated fatty acid-{beta}-oxidizing syntrophic bacteria, Syntrophomonas sapovorans and Syntrophomonas wolfei LYB, and sequence analysis confirmed their classification as members of the family Syntrophomonadaceae. S.wolfei LYB was closely related to S.wolfei subsp. solfei, but S. sapovorans did not cluster with the other members of the genus Syntrophomonas. Five oligonucleotide probes targeting the small-subunit rRNA of different groups within the family Syntrophomonadaceae, which contains all currently known saturated fatty acid-{beta}-oxidizing syntrophic bacteria, were developed and characterized. The probes were designed to be specific at the family, genus, and species levels and were characterized by temperature-of-dissociation and specificity studies. To demonstrate the usefulness of the probes for the detection and quantification of saturated fatty acid-{beta}-oxidizing syntrophic bacteria in methanogenic environments, the microbial community structure of a sample from a full-scale biogas plant was determined. Hybridization results with probes for syntrophic bacteria and methanogens were compared to specific methanogenic activities and microbial numbers determined with most-probable-number estimates. Most of the methanogenic rRNA was comprised of Methanomicrobiales rRNA, suggesting that members of this order served as the main hydrogen-utilizing microorganisms. Between 0.2 and 1% of the rRNA was attributed to the Syntrophomonadaceae, or which the majority was accounted for by the genus Syntrophomonas.

Hansen, K.H.; Ahring, B.K.; Raskin, L.

1999-11-01

48

Biogas from waste in Belgium  

SciTech Connect

This article describes plans for a dry anaerobic composting plant in Brecht, Belgium. The new plant will utilize dry conditions and thermophilic temperatures to produce an average of 6 to 8 volumes of biogas per volume of reactor per day could be produced from vegetable, fruit, garden and paper waste, and a soil amendment from the organic fraction of municipal solid waste according to researchers.

Not Available

1991-08-01

49

Performance comparison between mesophilic and thermophilic anaerobic reactors for treatment of palm oil mill effluent.  

PubMed

The anaerobic digestion of palm oil mill effluent (POME) was carried out under mesophilic (37°C) and thermophilic (55°C) conditions without long-time POME storage in order to compare the performance of each condition in the field of Sumatra Island, Indonesia. The anaerobic treatment system was composed of anaerobic hybrid reactor and anaerobic baffled filter. Raw POME was pretreated by screw decanter to reduce suspended solids and residual oil. The total COD removal rate of 90-95% was achieved in both conditions at the OLR of 15kg[COD]/m(3)/d. The COD removal in thermophilic conditions was slightly better, however the biogas production was much higher than that in the mesophilic one at high OLR. The organic contents in pretreated POME were highly biodegradable in mesophilic under the lower OLRs. The biogas production was 13.5-20.0l/d at the 15kg[COD]/m(3)/d OLR, and the average content of carbon dioxide was 5-35% in both conditions. PMID:24797939

Jeong, Joo-Young; Son, Sung-Min; Pyon, Jun-Hyeon; Park, Joo-Yang

2014-08-01

50

Methods for increasing the biogas potential from the recalcitrant organic matter contained in manure  

Microsoft Academic Search

The biogas potential of manure could be significantly increased by treatment of the recalcitrant organic matter (biofibers) contained in the manure. Several treatment methods were tested. Mechanical maceration resulted in an average increase of the biogas potential of approximately 17% as shown by the continuous stirred reactor experiment. In general the smaller the fibers the higher the biogas potential was.

I. Angelidaki; B. K. Ahring

51

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

PubMed

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. PMID:24960022

Davutluoglu, Orkun I; Seckin, Galip

2014-01-01

52

Hydraulic characteristics and their effects on working performance of compartmentalized anaerobic reactor.  

PubMed

The compartmentalized anaerobic reactor (CAR) is a patent novel high-rate reactor and shows a great potential for its application. The hydraulic characteristics and their effects on the working performance of CAR were investigated. The flow pattern tended to plug flow at normal organic loading rate (OLR) and completely mixed flow at high OLRs. The relation of hydraulic dead space (HDS or V(h)) with hydraulic loading rate (HLR or L) and biogas production rate (BPR or G) was V(h) = 3.75 L + 0.19 G-9.47. The hydraulic efficiency of CAR was good or near to good. Both HLR and BPR had significant effects on the hydraulic efficiency, but their effect became less at super-high OLR. They also had a slight influence on the effective volume ratios of CAR, but the influence of BPR almost disappeared at super-high OLR. The good working performance of CAR was ascribed to the improved reactor configuration. PMID:22609654

Ji, Jun-yuan; Zheng, Kai; Xing, Ya-juan; Zheng, Ping

2012-07-01

53

Performance of expanded-bed methanogenic reactor  

SciTech Connect

A completely mixed, expanded-bed, anaerobic granular activated carbon reactor was operated continuously on synthetic wastewaters in which acetate was the only organic carbon source. Steady-state performance was achieved for four influent acetate concentrations, namely: 800, 1600, 3200, and 6400 mg/l. Steady-state removal efficiencies of acetate, COD, and DOC exceeded 98, 97 and 98%, respectively. Biological utilization was the major removal mechanism for acetate in the anaerobic filter. This process was demonstrated to be capable of purifying low strength wastewaters down to levels that are acceptable for final discharge. 16 references.

Wang. Y.T.; Suidan, M.T.; Rittman, B.E.

1985-08-01

54

List of publications 1. Sun, L., Mller, B. and Schnrer, A. (2013) Biogas production from wheat straw community  

E-print Network

List of publications 1. Sun, L., Müller, B. and Schnürer, A. (2013) Biogas production from wheat biogas digesters. Biores. Technol. 132, 327­332 4. Manzoor, S., Müller, B., Niazi A., Bongcam-Rudloff E of syntrophic acetate- oxidising culture in biogas reactors exposed to increasing levels of ammonia. Applied

55

Electricity from biogas  

SciTech Connect

Biogas is a medium-Btu methane and carbon dioxide mix produced by bacterial decomposition of organic matter. Its sources include landfills, waste water sludges, and animal wastes. It can fuel energy applications, of which electricity generation is a frequently-preferred option. The greatest current U.S. biogas recovery and energy use is at landfills, where biogas at about 80 landfill sites fuels a total of approximately 300 MWe. Wastewater treatment plants and confined animal waste management systems support additional electric power production. Generation of electricity from biogas can present difficulties due to the generally small scale of the generating facility, variable energy content of the gas, fluctuating availability, contaminant problems, and often-demanding control needs. However, such difficulties are being successfully addressed and economics for electricity generation are often favorable as biogas can be essentially {open_quotes}free{close_quotes} fuel. Biogas recovery and use has the additional advantage of mitigating a potent greenhouse gas. Biogas from U.S. landfills alone could fuel about 1% of U.S. electrical generation while giving climate change benefit equivalent to reducing CO{sub 2} emissions in the electricity sector by more than 10%. Growth in landfill gas use will be facilitated by recent regulations, advances in equipment, and improved management techniques such as {open_quotes}controlled landfilling{close_quotes}. The potential for biogas recovery and electricity production from sewage sludges, animal wastes and other organic resources such as agricultural residues is uncertain but probably exceeds the estimate for landfills.

Augenstein, D.; Benemann, J. [Institute for Environmental Management, Palo Alto, CA (United States); Hughes, E. [Electric Power Research Institute, Palo Alto, CA (United States)

1994-12-31

56

Oxidation performance of graphite material in reactors  

Microsoft Academic Search

Graphite is used as a structural material and moderator for high temperature gas-cooled reactors (HTGR). When a reactor is\\u000a in operation, graphite oxidation influences the safety and operation of the reactor because of the impurities in the coolant\\u000a and\\/or the accident conditions, such as water ingress and air ingress. In this paper, the graphite oxidation process is introduced,\\u000a factors influencing

Xiaowei Luo; Xinli Yu; Suyuan Yu

2008-01-01

57

Effect of some operating parameters on biogas production rate  

Microsoft Academic Search

In order to enhance the performance of a biogas generation process and prevent process failure, certain operataing parameters need to be controlled. This article presents the results of a series of studies in which the effect of temperature, pH, carbon -nitrogen ratio and retention time on biogas production from cowdung were investigated

A. S. Sambo; B. Garba; B. G. Danshehu

1995-01-01

58

Production and energetic use of biogas from energy crops and wastes in Germany  

Microsoft Academic Search

The production of biogas for reducing fossil CO2 emissions is one of the key strategic issues of the German government and has resulted in the development of new process\\u000a techniques and new technologies for the energetic use of biogas. Progress has been made in cultivating energy crops for biogas\\u000a production, in using new reactor systems for anaerobic digestion, and in

Peter Weiland

2003-01-01

59

Trace compounds of biogas from different biogas production plants  

Microsoft Academic Search

Biogas composition and variation in three different biogas production plants were studied to provide information pertaining to its potential use as biofuel. Methane, carbon dioxide, oxygen, nitrogen, volatile organic compounds (VOCs) and sulphur compounds were measured in samples of biogases from a landfill, sewage treatment plant sludge digester and farm biogas plant. Methane content ranged from 48% to 65%, carbon

S. Rasi; A. Veijanen; J. Rintala

2007-01-01

60

Fuel performance experience from the nuclear power demonstration reactor  

SciTech Connect

The nuclear power demonstration (NPD) reactor was the first Canadian power reactor and precursor of the later Douglas Point Canada Deuterium Uranium (CANDU) pressurized heavy-water reactor prototype reactor. The 25-MW(electric) NPD was a joint venture of Atomic Energy of Canada Limited, Ontario Hydro and Canadian General Electric Corporation (now GE Canada Incorporated), and commenced service in 1962. It was shut down finally in 1987 and was decommission in 1988. About 26 fuel tests were done in NPD; these have provided significant data on extended burnup fuel performance and power ramp behavior.

Carter, T.J.; Smith, A.D.; Lusk, I.A.

1989-01-01

61

Biogas energy technology in Sudan  

Microsoft Academic Search

Biogas from biomass appears to have potential as an alternative energy in Sudan, which is potentially rich in biomass resources. This is an overview of some salient points and perspectives of biogas technology in Sudan. The current literature is reviewed regarding the ecological, social, cultural and economic impacts of biogas technology. Sudan is blessed with abundant solar, wind, hydro, and

A. M. Omer; Y. Fadalla

2003-01-01

62

Transient two-phase performance of LOFT reactor coolant pumps  

SciTech Connect

Performance characteristics of Loss-of-Fluid Test (LOFT) reactor coolant pumps under transient two-phase flow conditions were obtained based on the analysis of two large and small break loss-of-coolant experiments conducted at the LOFT facility. Emphasis is placed on the evaluation of the transient two-phase flow effects on the LOFT reactor coolant pump performance during the first quadrant operation. The measured pump characteristics are presented as functions of pump void fraction which was determined based on the measured density. The calculated pump characteristics such as pump head, torque (or hydraulic torque), and efficiency are also determined as functions of pump void fractions. The importance of accurate modeling of the reactor coolant pump performance under two-phase conditions is addressed. The analytical pump model, currently used in most reactor analysis codes to predict transient two-phase pump behavior, is assessed.

Chen, T.H.; Modro, S.M.

1983-01-01

63

A review on optimization production and upgrading biogas through CO2 removal using various techniques.  

PubMed

Biogas from anaerobic digestion of organic materials is a renewable energy resource that consists mainly of CH4 and CO2. Trace components that are often present in biogas are water vapor, hydrogen sulfide, siloxanes, hydrocarbons, ammonia, oxygen, carbon monoxide, and nitrogen. Considering the biogas is a clean and renewable form of energy that could well substitute the conventional source of energy (fossil fuels), the optimization of this type of energy becomes substantial. Various optimization techniques in biogas production process had been developed, including pretreatment, biotechnological approaches, co-digestion as well as the use of serial digester. For some application, the certain purity degree of biogas is needed. The presence of CO2 and other trace components in biogas could affect engine performance adversely. Reducing CO2 content will significantly upgrade the quality of biogas and enhancing the calorific value. Upgrading is generally performed in order to meet the standards for use as vehicle fuel or for injection in the natural gas grid. Different methods for biogas upgrading are used. They differ in functioning, the necessary quality conditions of the incoming gas, and the efficiency. Biogas can be purified from CO2 using pressure swing adsorption, membrane separation, physical or chemical CO2 absorption. This paper reviews the various techniques, which could be used to optimize the biogas production as well as to upgrade the biogas quality. PMID:24293277

Andriani, Dian; Wresta, Arini; Atmaja, Tinton Dwi; Saepudin, Aep

2014-02-01

64

Liquid membrane purification of biogas  

SciTech Connect

Conventional gas purification technologies are highly energy intensive. They are not suitable for economic removal of CO{sub 2} from methane obtained in biogas due to the small scale of gas production. Membrane separation techniques on the other hand are ideally suited for low gas production rate applications due to their modular nature. Although liquid membranes possess a high species permeability and selectivity, they have not been used for industrial applications due to the problems of membrane stability, membrane flooding and poor operational flexibility, etc. A new hollow-fiber-contained liquid membrane (HFCLM) technique has been developed recently. This technique overcomes the shortcomings of the traditional immobilized liquid membrane technology. A new technique uses two sets of hydrophobic, microporous hollow fine fibers, packed tightly in a permeator shell. The inter-fiber space is filled with an aqueous liquid acting as the membrane. The feed gas mixture is separated by selective permeation of a species through the liquid from one fiber set to the other. The second fiber set carries a sweep stream, gas or liquid, or simply the permeated gas stream. The objectives (which were met) of the present investigation were as follows. To study the selective removal of CO{sub 2} from a model biogas mixture containing 40% CO{sub 2} (the rest being N{sub 2} or CH{sub 4}) using a HFCLM permeator under various operating modes that include sweep gas, sweep liquid, vacuum and conventional permeation; to develop a mathematical model for each mode of operation; to build a large-scale purification loop and large-scale permeators for model biogas separation and to show stable performance over a period of one month.

Majumdar, S.; Guha, A.K.; Lee, Y.T.; Papadopoulos, T.; Khare, S. (Stevens Inst. of Tech., Hoboken, NJ (United States). Dept. of Chemistry and Chemical Engineering)

1991-03-01

65

Anaerobic digestion of Chinese cabbage waste silage with swine manure for biogas production: batch and continuous study.  

PubMed

The aim of this study was to investigate the potential for anaerobic co-digestion of Chinese cabbage waste silage (CCWS) with swine manure (SM). Batch and continuous experiments were carried out under mesophilic anaerobic conditions (36-38°C). The batch test evaluated the effect of CCWS co-digestion with SM (SM: CCWS=100:0; 25:75; 33:67; 0:100, % volatile solids (VS) basis). The continuous test evaluated the performance of a single stage completely stirred tank reactor with SM alone and with a mixture of SM and CCWS. Batch test results showed no significant difference in biogas yield up to 25-33% of CCWS; however, biogas yield was significantly decreased when CCWS contents in feed increased to 67% and 100%. When testing continuous digestion, the biogas yield at organic loading rate (OLR) of 2.0 g VSL?¹ d?¹ increased by 17% with a mixture of SM and CCWS (SM:CCWS=75:25) (423 mL g?¹ VS) than with SM alone (361 mL g?¹ VS). The continuous anaerobic digestion process (biogas production, pH, total volatile fatty acids (TVFA) and TVFA/total alkalinity ratios) was stable when co-digesting SM and CCWS (75:25) at OLR of 2.0 g VSL?¹ d?¹ and hydraulic retention time of 20 days under mesophilic conditions. PMID:25176305

Kafle, Gopi Krishna; Bhattarai, Sujala; Kim, Sang Hun; Chen, Lide

2014-01-01

66

Metallurgical processing and pulsed reactor fuel performance  

Microsoft Academic Search

Metallurgical methods for improving fuel performance were studied. It was concluded that fatigue failure is responsible for fuel fractures and that changes in fuel processing are the most practical means of achieving improvement. A hot forging step was chosen for investigation. Four prototype fuel plates of depleted U-10Mo alloy were produced, two by conventional casting and two by upset forging

J. P. Hickerson Jr.; J. P. Jr

1974-01-01

67

Performance and safety parameters for the high flux isotope reactor  

SciTech Connect

A Monte Carlo depletion model for the High Flux Isotope Reactor (HFIR) Cycle 400 and its use in calculating parameters of relevance to the reactor performance and safety during the reactor cycle are presented in this paper. This depletion model was developed to serve as a reference for the design of a low-enriched uranium (LEU) fuel for an ongoing study to convert HFIR from high-enriched uranium (HEU) to LEU fuel; both HEU and LEU depletion models use the same methodology and ENDF/B-VII nuclear data as discussed in this paper. The calculated HFIR Cycle 400 parameters, which are compared with measurement data from critical experiments performed at HFIR, data included in the HFIR Safety Analysis Report (SAR), or data reported by previous calculations, provide a basis for verification or updating of the corresponding SAR data. (authors)

Ilas, G. [Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831-6172 (United States); Primm III, T. [Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831-6172 (United States); Primm Consulting, LLC, 945 Laurel Hill Road, Knoxville, TN 37923 (United States)

2012-07-01

68

Ecological analysis of a typical farm-scale biogas plant in China  

NASA Astrophysics Data System (ADS)

The aim of this work was to present the common anaerobic digestion technologies in a typical farm-scale biogas plant in China. The comprehensive benefits of most biogas plants in China have not been fully assessed in past decades due to the limited information of the anaerobic digestion processes in biogas plants. This paper analyzed four key aspects (i.e., operational performance, nonrenewable energy (NE) savings, CO2 emission reduction (CER) and economic benefits (EBs)) of a typical farm-scale biogas plant, where beef cattle manure was used as feedstock. Owing to the monitoring system, stable operation was achieved with a hydraulic retention time of 18-22 days and a production of 876,000 m3 of biogas and 37,960 t of digestate fertilizer annually. This could substantially substitute for the nonrenewable energy and chemical fertilizer. The total amount of NE savings and CER derived from biogas and digestate fertilizer was 2.10×107 MJ (equivalent to 749.7 tce) and 9.71×105 kg, respectively. The EBs of the biogas plant was 6.84×105 CNY·yr-1 with an outputs-to-inputs ratio of 2.37. As a result, the monitoring system was proved to contribute significantly to the sound management and quantitative assessment of the biogas plant. Biogas plants could produce biogas which could be used to substitute fossil fuels and reduce the emissions of greenhouse gases, and digestate fertilizer is also an important bio-product.

Duan, Na; Lin, Cong; Wang, Pingzhi; Meng, Jing; Chen, Hui; Li, Xue

2014-09-01

69

Microbial community structure and dynamics during co-digestion of whey permeate and cow manure in continuous stirred tank reactor systems.  

PubMed

Microbial community profiles in two parallel CSTR biogas reactors fed with whey permeate and cow manure were investigated. The operating conditions for these two reactors were identical, yet only one of them (R1) showed stable performance, whereas the other (R2) showed a decrease in methane production accompanied by accumulation of propionic acid and, later, acetic acid. This gave a unique opportunity to study the dynamics of the microbial communities in two biogas reactors apparently operating close to the edge of stability. The microbial community was dominated by Bacteroidetes and Firmicutes, and the methanogens Methanobacteriales and Methanomicrobiales in both reactors, but with larger fluctuations in R2. Correlation analyses showed that the depletion of propionic acid in R1 and the late increase of acetic acid in R2 was related to several bacterial groups. The biogas production in R1 shows that stable co-digestion of manure and whey can be achieved with reasonable yields. PMID:25222739

Hagen, Live Heldal; Vivekanand, Vivekanand; Linjordet, Roar; Pope, Phillip B; Eijsink, Vincent G H; Horn, Svein J

2014-11-01

70

Biogas production from olive pomace  

Microsoft Academic Search

Biogas production from a slurry obtained by mixing finely ground olive pomace in water was investigated using anaerobic digesters of 1-l working volume at 37°C. A start-up culture was obtained from a local landfill area and was adopted to the slurry within 10 days at this temperature. The biogas generation rates were determined by varying the total solids (TS) concentration

Ali R Tekin; A. Co?kun Dalg?ç

2000-01-01

71

Shell structures for biogas plants  

SciTech Connect

The shell structures designed for biogas plants of the fixed-dome type by the Bremen Overseas Research and Development Association are described. Biogas digesters of the design described have been successfully tested in Rwanda and India without structural or contractural problems.

Sasse, L.

1982-01-01

72

Computational Neutronics Methods and Transmutation Performance Analyses for Fast Reactors  

SciTech Connect

The once-through fuel cycle strategy in the United States for the past six decades has resulted in an accumulation of Light Water Reactor (LWR) Spent Nuclear Fuel (SNF). This SNF contains considerable amounts of transuranic (TRU) elements that limit the volumetric capacity of the current planned repository strategy. A possible way of maximizing the volumetric utilization of the repository is to separate the TRU from the LWR SNF through a process such as UREX+1a, and convert it into fuel for a fast-spectrum Advanced Burner Reactor (ABR). The key advantage in this scenario is the assumption that recycling of TRU in the ABR (through pyroprocessing or some other approach), along with a low capture-to-fission probability in the fast reactor’s high-energy neutron spectrum, can effectively decrease the decay heat and toxicity of the waste being sent to the repository. The decay heat and toxicity reduction can thus minimize the need for multiple repositories. This report summarizes the work performed by the fuel cycle analysis group at the Idaho National Laboratory (INL) to establish the specific technical capability for performing fast reactor fuel cycle analysis and its application to a high-priority ABR concept. The high-priority ABR conceptual design selected is a metallic-fueled, 1000 MWth SuperPRISM (S-PRISM)-based ABR with a conversion ratio of 0.5. Results from the analysis showed excellent agreement with reference values. The independent model was subsequently used to study the effects of excluding curium from the transuranic (TRU) external feed coming from the LWR SNF and recycling the curium produced by the fast reactor itself through pyroprocessing. Current studies to be published this year focus on analyzing the effects of different separation strategies as well as heterogeneous TRU target systems.

R. Ferrer; M. Asgari; S. Bays; B. Forget

2007-03-01

73

On-line performance monitoring for boiling water reactor plants  

SciTech Connect

While fossil plants have utilized on-line performance monitoring for reducing heat rate, nuclear plants have traditionally employed off-line tools to improve plant efficiency. However, any increase in plant output while maintaining reactor heat input is easily justified. Thus on-line performance monitoring on boiling water reactor (BWR) plants to locate power losses in the cycle is useful in maximizing the capacity of the plant. In addition, it is quite valuable to use an off-line predictive model to perform what-if analyses and to retrieve and display plant data in a variety of formats. This paper presents an overview of the unique software product jointly developed by GE Nuclear Energy and Black and Veatch, including a description of the software capabilities, sample screens and reports, and typical applications of the product.

Josyula, R. [General Electric Nuclear Energy, San Jose, CA (United States); Gross, R.; Jonas, T.; Logback, F. [Black and Veatch, Kansas City, MO (United States)

1995-10-01

74

Upscaling of an electronic nose for completely stirred tank reactor stability monitoring from pilot-scale to real-scale agricultural co-digestion biogas plant.  

PubMed

This study investigated the use of an electronic nose for on-line anaerobic reactor state monitoring at the pilot-scale level and then upscaling to the full-scale level. E-nose indicator was compared to classical state indicators such as pH, alkalinity, volatile fatty acids concentration and to other gas phase compounds. Multivariate statistical process control method, based on principal component analysis and the Hotelling's T(2) statistics was used to derive an indicator representative of the reactor state. At the pilot-scale level, the e-nose indicator was relevant and could distinguish 3 process states: steady-state, transient and collapsing process. At the full-scale level, the e-nose indicator could provide the warning of the major disturbance whereas two slight disturbances were not detected and it gave one major false alarm. This work showed that gas phase relation with anaerobic process should be deeper investigated, as an e-nose could indicate the reactor state, focusing on the gas phase. PMID:25446784

Adam, Gilles; Lemaigre, Sébastien; Goux, Xavier; Delfosse, Philippe; Romain, Anne-Claude

2015-02-01

75

Augmented biogas production from protein-rich substrates and associated metagenomic changes.  

PubMed

This study demonstrates that appropriate adaptation of the microbial community to protein-rich biomass can lead to sustainable biogas production. The process of acclimation to these unusual mono-substrates was controlled by the protease activity of the microbial community. Meat extract (C/N=3.32) and kitchen waste (C/N=12.43) were used as biogas substrates. Metagenome analysis highlighted several mesophilic strains that displayed a preference for protein degradation. Bacillus coagulans, Bacillus subtilis and Pseudomonas fluorescens were chosen for detailed investigation. Pure cultures were added to biogas reactors fed solely with protein-rich substrates. The bioaugmentation resulted in a 50% increase in CH4 production even without any acclimation. The survival and biological activity of the added bacteria were followed in fed-batch fermenters by qPCR. Stable biogas production was observed for an extended period of time in laboratory CSTR reactors fed with biomass of low C/N. PMID:25316194

Kovács, Etelka; Wirth, Roland; Maróti, Gergely; Bagi, Zoltán; Nagy, Katalin; Minárovits, János; Rákhely, Gábor; Kovács, Kornél L

2015-02-01

76

Evaluating the biogas potential of the dry fraction from pretreatment of food waste from households  

SciTech Connect

Highlights: ? A novel approach for biogas production from a waste fraction that today is incinerated. ? Biogas production is possible in spite of the impurities of the waste. ? Tracer studies are applied in a novel way. ? Structural material is needed to improve the flow pattern of the waste. ? We provide a solution to biological treatment for the complex waste fraction. - Abstract: At the waste handling company NSR, Helsingborg, Sweden, the food waste fraction of source separated municipal solid waste is pretreated to obtain a liquid fraction, which is used for biogas production, and a dry fraction, which is at present incinerated. This pretreatment and separation is performed to remove impurities, however also some of the organic material is removed. The possibility of realising the methane potential of the dry fraction through batch-wise dry anaerobic digestion was investigated. The anaerobic digestion technique used was a two-stage process consisting of a static leach bed reactor and a methane reactor. Treatment of the dry fraction alone and in a mixture with structural material was tested to investigate the effect on the porosity of the leach bed. A tracer experiment was carried out to investigate the liquid flow through the leach beds, and this method proved useful in demonstrating a more homogenous flow through the leach bed when structural material was added. Addition of structural material to the dry fraction was needed to achieve a functional digestion process. A methane yield of 98 m{sup 3}/ton was obtained from the dry fraction mixed with structural material after 76 days of digestion. This was in the same range as obtained in the laboratory scale biochemical methane potential test, showing that it was possible to extract the organic content in the dry fraction in this type of dry digestion system for the production of methane.

Murto, Marika, E-mail: marika.murto@biotek.lu.se [Department of Biotechnology, Lund University, P.O. Box 124, SE-221 00 Lund (Sweden); Björnsson, Lovisa, E-mail: lovisa.bjornsson@miljo.lth.se [Department of Biotechnology, Lund University, P.O. Box 124, SE-221 00 Lund (Sweden); Environmental and Energy Systems Studies, Lund University, P.O. Box 118, SE-221 00 Lund (Sweden); Rosqvist, Håkan, E-mail: hakan@rosqvist-resurs.se [Rosqvist Resurs, Gamla Malmövägen 25, SE-230 41 Klågerup (Sweden); Bohn, Irene, E-mail: irene.bohn@nsr.se [NSR AB, Hjortshögsvägen 1, SE-251 89 Helsingborg (Sweden)

2013-05-15

77

High Performance Fuel Desing for Next Generation Pressurized Water Reactors  

SciTech Connect

The use of internally and externally cooled annular fule rods for high power density Pressurized Water Reactors is assessed. The assessment included steady state and transient thermal conditions, neutronic and fuel management requirements, mechanical vibration issues, fuel performance issues, fuel fabrication methods and econmic assessment. The investigation was donducted by a team from MIT, Westinghouse, Gamma Engineering, Framatome ANP, and AECL. The analyses led to the conclusion that raising the power density by 50% may be possible with this advanced fuel. Even at the 150% power level, the fuel temperature would be a few hundred degrees lower than the current fuel temperatre. Significant economic and safety advantages can be obtained by using this fuel in new reactors. Switching to this type of fuel for existing reactors would yield safety advantages, but the economic return is dependent on the duration of plant shutdown to accommodate higher power production. The main feasiblity issue for the high power performance appears to be the potential for uneven splitting of heat flux between the inner and outer fuel surfaces due to premature closure of the outer fuel-cladding gap. This could be overcome by using a very narrow gap for the inner fuel surface and/or the spraying of a crushable zirconium oxide film at the fuel pellet outer surface. An alternative fuel manufacturing approach using vobropacking was also investigated but appears to yield lower than desirable fuel density.

Mujid S. Kazimi; Pavel Hejzlar

2006-01-31

78

LQG\\/LTR robust control of nuclear reactors with improved temperature performance  

Microsoft Academic Search

The authors present the design of a robust controller using the linear quadratic Gaussian with loop transfer recovery (LQG\\/LTR) for nuclear reactors with the objective of maintaining a desirable performance for reactor fuel temperature and the temperature of the coolant leaving the reactor for a wide range of reactor powers. The results obtained are compared to those for an observer-based

Adel Ben-Abdennour; Robert M. Edwards; Kwang Y. Lee

1992-01-01

79

Biogenic Hydrogen Conversion of De-Oiled Jatropha Waste via Anaerobic Sequencing Batch Reactor Operation: Process Performance, Microbial Insights, and CO2 Reduction Efficiency  

PubMed Central

We report the semicontinuous, direct (anaerobic sequencing batch reactor operation) hydrogen fermentation of de-oiled jatropha waste (DJW). The effect of hydraulic retention time (HRT) was studied and results show that the stable and peak hydrogen production rate of 1.48?L/L?d and hydrogen yield of 8.7?mL?H2/g volatile solid added were attained when the reactor was operated at HRT 2 days (d) with a DJW concentration of 200?g/L, temperature 55°C, and pH 6.5. Reduced HRT enhanced the production performance until 1.75?d. Further reduction has lowered the process efficiency in terms of biogas production and hydrogen gas content. The effluent from hydrogen fermentor was utilized for methane fermentation in batch reactors using pig slurry and cow dung as seed sources. The results revealed that pig slurry was a feasible seed source for methane generation. Peak methane production rate of 0.43?L CH4/L?d and methane yield of 20.5?mL CH4/g?COD were observed at substrate concentration of 10?g?COD/L, temperature 30°C, and pH 7.0. PCR-DGGE analysis revealed that combination of celluloytic and fermentative bacteria were present in the hydrogen producing ASBR. PMID:24672398

Lin, Chiu-Yue

2014-01-01

80

Plasma performance study for the tandem mirror reactor  

SciTech Connect

A computer code was developed for assessing the performance of new variations on the thermal barrier idea for tandem mirror reactors (TMR's). The code solves the particle and energy balance equations simultaneously for each species of particles in each portion of the machine. The code is thus able to determine the neutral beam and ECRH injection powers that are required to sustain an equilibrium situation, and, from these, to determine the machine's Q value. This paper focuses on the methodology and numerical algorithms used in accomplishing this solution. We plan to use this code to compare the A-cell barrier TMR with axisymmetric TMR's.

Boghosian, B.M.

1980-01-01

81

Evolutionary mixed-oxide fuel performance in pressurized water reactors  

SciTech Connect

Investigations of an advanced fuel form are currently under way at Los Alamos National Laboratory. This new fuel form, referred to as evolutionary mixed oxide (EMOX), is a slight perturbation on standard mixed-oxide (MOX) fuel, and analyses show that it can be an effective plutonium management tool in existing light water reactors. The addition of a small fraction of calcia-stabilized zirconia to the uranium-plutonium oxide matrix allows for greater plutonium conversion while also providing a licensing path forward toward eventual implementation of higher plutonium destruction fuels. These fuels, referred to as nonfertile (NF) fuels, achieve their high destruction rates through the absence of uranium, which breeds plutonium, in the fuel composition. Extensive calculations have been performed to assess the feasibility of incorporating the EMOX fuel form into existing pressurized water reactor (PWR) systems, and the results are presented in this paper. Specifically, calculations have been made to determine the plutonium consumption achievable by the EMOX concept, and comparisons have been made of this performance with that of typical MOX and NF fuels.

Eaton, S.L.; Beard, C.A.; Buksa, J.J. [Los Alamos National Laboratory, NM (United States)

1996-12-31

82

Economic viability of biogas technology  

SciTech Connect

Biogas has emerged as a suitable technology for providing alternative and additional sources of energy, especially for rural areas of developing countries. Although the experience gained in China and India established its technological success, social scientists are still involved in the controversial issue of its economic viability. The available literature presents very contradictory situations, ranging between the two extreme poles of high economic viability and nonviability. Such contradictory conclusions are derived since economic benefits from the technology are influenced by a number of factors. A review of the literature reveals that various factors are either not considered, or that the economics have been worked out assuming a very ideal situation, while biogas plants are operating under very different conditions. Using the coal replacement method even as coal is seldom used by villages is only a single example of this approach. In most of the developing countries, rural populations depend mainly on non-commercial fuels like firewood, dungcakes, agricultural wastes and leaves for cooking and heating purposes. Under the present technological limitations, biogas can most commonly be used for cooking and lighting. For testing the economic viability of biogas systems, a number of authors have considered the benefits in terms of savings in traditional fuels. But considering the actual thermal efficiency of different non-commercial fuel items, as well as biogas, it has still be be decided at what point of the market prices of fuel items that the biogas system becomes economically viable and remains viable. The present paper thus reviews different approaches adopted and suggested for working out the economics or the cost-benefit ratio of the biogas technology at the first stage, and then spells out the factors influencing the economic benefits of the technology under various situations, with the help of empirical

Agrawal, S.C.; Agrawal, S.; Khare, O.P.

1983-12-01

83

Biogas production from Jatropha curcas press-cake  

SciTech Connect

Seeds of the tropical plant Jatropha curcas (purge nut, physic nut) are used for the production of oil. Several methods for oil extraction have been developed. In all processes, about 50% of the weight of the seeds remain as a press cake containing mainly protein and carbohydrates. Investigations have shown that this residue contains toxic compounds and cannot be used as animal feed without further processing. Preliminary experiments have shown that the residue is a good substrate for biogas production. Biogas formation was studied using a semicontinous upflow anaerobic sludge blanket (UASB) reactor; a contact-process and an anaerobic filter each reactor having a total volume of 110 L. A maximum production rate of 3.5 m{sup 3} m{sup -3} d{sup -1} was obtained in the anaerobic filter with a loading rate of 13 kg COD m{sup -3} d{sup -1}. However, the UAS reactor and the contact-process were not suitable for using this substrate. When using an anaerobic filter with Jatropha curcas seed cake as a substrate, 76% of the COD was degraded and 1 kg degraded COD yielded 355 L of biogas containing 70% methane. 28 refs., 3 figs., 4 tabs.

Staubmann, R.; Guebitz, G.M.; Lafferty, R.M. [Graz Technical Univ. (Austria)] [and others

1997-12-31

84

Introduction to biogas production on the farm  

SciTech Connect

A number of farmers, ranchers, and engineers received support from the US Department of Energy Appropriate Technology Small Grants Program to design, construct, and demonstrate biogas production systems. Many of these projects generated more than just biogas; grantees' work and results have contributed to a growing body of information about practical applications of this technology. This publication was developed to share some of that information, to answer the basic questions about biogas production, and to lead farmers to more information. Section I introduces biogas and the various components of a biogas production system, discusses the system's benefits and liabilities, and provides a brief checklist to determine if biogas production may be applicable to an individual's particular situation. Section II features descriptions of four biogas projects of various sizes. Section III provides sources of additional information including descriptions of other biogas production projects.

Not Available

1984-03-01

85

Thermal analysis of a simple-cycle gas turbine in biogas power generation  

SciTech Connect

This paper investigates the technical feasibility of utilizing small simple-cycle gas turbines (25 kW to 125 kW) for biogas power generation through thermal analysis. A computer code, GTPower, was developed to evaluate the performance of small simple-cycle gas turbines specifically for biogas combustion. The 125 KW Solar Gas Turbine (Tital series) has been selected as the base case gas turbine for biogas combustion. After its design parameters and typical operating conditions were entered into GTPower for analysis, GTPower outputted expected values for the thermal efficiency and specific work. For a sensitivity analysis, the GTPower Model outputted the thermal efficiency and specific work. For a sensitivity analysis, the GTPower Model outputted the thermal efficiency and specific work profiles for various operating conditions encountered in biogas combustion. These results will assist future research projects in determining the type of combustion device most suitable for biogas power generation.

Yomogida, D.E. [California Energy Commission, Sacramento, CA (United States); Thinh, Ngo Dinh [California State Univ., Sacramento, CA (United States)

1995-09-01

86

The Utilization of Non-edible Oil Cake Along With Cow Dung for Methane-enriched Biogas Production Using Mixed Inoculum  

Microsoft Academic Search

Different proportions (i.e., 25, 50 and 75%) of each of the non-edible oil cakes such as jatropha, karanja and safflower along with cow dung was studied for biogas production in a 1 L batch reactor using mixed inoculum IRP (a combination of inoculum from a biogas plant, municipal waste digester and rice paddy soil adopted on cow dung). The range

R. Singh; S. K. Mandal

2011-01-01

87

Elimination of high concentration hydrogen sulfide and biogas purification by chemical-biological process.  

PubMed

A chemical-biological process was performed to remove a high concentration of H2S in biogas. The high iron concentration tolerance (20gL(-1)) of Acidithiobacillus ferrooxidans CP9 provided sufficient ferric iron level for stable and efficient H2S elimination. A laboratory-scale apparatus was setup for a 45 d operation to analyze the optimal conditions. The results reveal that the H2S removal efficiency reached 98% for 1500ppm H2S. The optimal ferric iron concentration was kept between 9 and 11gL(-1) with a cell density of 10(8)CFUg(-1) granular activated carbon and a loading of 15gSm(-3)h(-1). In pilot-scale studies for biogas purification, the average inlet H2S concentration was 1645ppm with a removal efficiency of up to 97% for a 311d operation and an inlet loading 40.8gSm(-3)h(-1). When 0.1% glucose was added, the cell density increased twofold under the loading of 65.1gSm(-3)h(-1) with an H2S removal efficiency still above 96%. The analysis results of the distribution of microorganisms in the biological reactor by DGGE show that microorganism populations of 96.7% and 62.7% were identical to the original strain at day 200 and day 311, respectively. These results clearly demonstrate that ferric iron reduction by H2S and ferrous iron oxidation by A. ferrooxidans CP9 are feasible processes for the removal of H2S from biogas. PMID:23791111

Ho, Kuo-Ling; Lin, Wei-Chih; Chung, Ying-Chien; Chen, Yu-Pei; Tseng, Ching-Ping

2013-08-01

88

Titer-plate formatted continuous flow thermal reactors: Design and performance of a nanoliter reactor  

PubMed Central

Arrays of continuous flow thermal reactors were designed, configured, and fabricated in a 96-device (12 × 8) titer-plate format with overall dimensions of 120 mm × 96 mm, with each reactor confined to a 8 mm × 8 mm footprint. To demonstrate the potential, individual 20-cycle (740 nL) and 25-cycle (990 nL) reactors were used to perform the continuous flow polymerase chain reaction (CFPCR) for amplification of DNA fragments of different lengths. Since thermal isolation of the required temperature zones was essential for optimal biochemical reactions, three finite element models, executed with ANSYS (v. 11.0, Canonsburg, PA), were used to characterize the thermal performance and guide system design: (1) a single device to determine the dimensions of the thermal management structures; (2) a single CFPCR device within an 8 mm × 8 mm area to evaluate the integrity of the thermostatic zones; and (3) a single, straight microchannel representing a single loop of the spiral CFPCR device, accounting for all of the heat transfer modes, to determine whether the PCR cocktail was exposed to the proper temperature cycling. In prior work on larger footprint devices, simple grooves between temperature zones provided sufficient thermal resistance between zones. For the small footprint reactor array, 0.4 mm wide and 1.2 mm high fins were necessary within the groove to cool the PCR cocktail efficiently, with a temperature gradient of 15.8°C/mm, as it flowed from the denaturation zone to the renaturation zone. With temperature tolerance bands of ±2°C defined about the nominal temperatures, more than 72.5% of the microchannel length was located within the desired temperature bands. The residence time of the PCR cocktail in each temperature zone decreased and the transition times between zones increased at higher PCR cocktail flow velocities, leading to less time for the amplification reactions. Experiments demonstrated the performance of the CFPCR devices as a function of flow velocity, fragment length, and copy number. A 99 bp DNA fragment was successfully amplified at flow velocities from 1 mm/s to 3 mm/s, requiring from 8.16 minutes for 20 cycles (24.48 s/cycle) to 2.72 minutes for 20 cycles (8.16 s/cycle), respectively. Yield compared to the same amplification sequence performed using a bench top thermal cycler decreased nonlinearly from 73% (at 1 mm/s) to 13% (at 3 mm/s) with shorter residence time at the optimal temperatures for the reactions due to increased flow rate primarily responsible. Six different DNA fragments with lengths between 99 bp and 997 bp were successfully amplified at 1 mm/s. Repeatable, successful amplification of a 99 bp fragment was achieved with a minimum of 8000 copies of the DNA template. This is the first demonstration and characterization of continuous flow thermal reactors within the 8 mm × 8 mm footprint of a 96-well micro-titer plate and is the smallest continuous flow PCR to date. PMID:20871807

Chen, Pin-Chuan; Park, Daniel S.; You, Byoung-Hee; Kim, Namwon; Park, Taehyun; Soper, Steven A.; Nikitopoulos, Dimitris E.; Murphy, Michael C.

2010-01-01

89

Effects of sawdust on biogas production from cowdung  

SciTech Connect

The biogas generation was performed using cowdung and sawdust in the ratios of 4:1 and 2:1, respectively. The experiments were also conducted using cowdung alone for the comparison purpose. The increase in the amount of sawdust in the mixture of cowdung and sawdust decreases the quantity of gas production. The production of methane up to three weeks is also effected by the amount of sawdust. The nitrogen contents increase and volatile solids decrease with the digestion of waste materials. The thermogravimetric studies of the materials support the biogas generation as the decomposition of particular part of cowdung.

Azmy, N.S. (Centre for Rural Development and Technology, Indian Inst. of Technology, Hauz Khas, New Delhi 110016 (IN)); Mishra, S. (Agriculture Research Centre, Soil and Water Research Inst., Microbiology Dept., Giza (EG)); Maheshwari, R.C. (Dept. of Chemistry, Birla Inst. of Technology and Science, Pilani, Rajasthan (IN))

1991-01-01

90

Application of neural network for simulation of upflow anaerobic sludge blanket (UASB) reactor performance.  

PubMed

Up-flow anaerobic sludge blanket (UASB) reactors are being used with increasing regularity all over the world, especially in India, for a variety of wastewater treatment operations. Consequently, there is a need to develop methodologies enabling one to determine UASB reactor performance, not only for designing more efficient UASB reactors but also for predicting the performance of existing reactors under various conditions of influent wastewater flows and characteristics. This work explores the feasibility of application of an artificial neural network-based model for simulating the performance of an existing UASB reactor. Accordingly, a neural network model was designed and trained to predict the steady-state performance of a UASB reactor treating high-strength (unrefined sugar based) wastewater. The model inputs were organic loading rate, hydraulic retention time, and influent bicarbonate alkalinity. The output variables were one or more of the following, effluent substrate concentration (Se), reactor bicarbonate alkalinity, reactor pH, reactor volatile fatty acid concentration, average gas production rate, and percent methane content of the gas. Training of the neural network model was achieved using a large amount of experimentally obtained reactor performance data from the reactor mentioned above as the training set. Training was followed by validation using independent sets of performance data obtained from the same UASB reactor. Subsequently, simulations were performed using the validated neural network model to determine the impact of changes in parameters like influent chemical oxygen demand (COD) concentration and hydraulic retention time on the reactor performance. Simulation results thus obtained were carefully analyzed based on qualitative understanding of UASB process and were found to provide important insights into key variables that were responsible for influencing the working of the UASB reactor under varying input conditions. PMID:11835141

Sinha, Sucheta; Bose, Purnendu; Jawed, Mohammed; John, Siby; Tare, Vinod

2002-03-30

91

Biogas Production from Citrus Waste by Membrane Bioreactor  

PubMed Central

Rapid acidification and inhibition by d-limonene are major challenges of biogas production from citrus waste. As limonene is a hydrophobic chemical, this challenge was encountered using hydrophilic polyvinylidine difluoride (PVDF) membranes in a biogas reactor. The more sensitive methane-producing archaea were encapsulated in the membranes, while freely suspended digesting bacteria were present in the culture as well. In this membrane bioreactor (MBR), the free digesting bacteria digested the citrus wastes and produced soluble compounds, which could pass through the membrane and converted to biogas by the encapsulated cell. As a control experiment, similar digestions were carried out in bioreactors containing the identical amount of just free cells. The experiments were carried out in thermophilic conditions at 55 °C, and hydraulic retention time of 30 days. The organic loading rate (OLR) was started with 0.3 kg VS/m3/day and gradually increased to 3 kg VS/m3/day. The results show that at the highest OLR, MBR was successful to produce methane at 0.33 Nm3/kg VS, while the traditional free cell reactor reduced its methane production to 0.05 Nm3/kg VS. Approximately 73% of the theoretical methane yield was achieved using the membrane bioreactor. PMID:25167328

Wikandari, Rachma; Millati, Ria; Cahyanto, Muhammad Nur; Taherzadeh, Mohammad J.

2014-01-01

92

Biogas production from citrus waste by membrane bioreactor.  

PubMed

Rapid acidification and inhibition by d-limonene are major challenges of biogas production from citrus waste. As limonene is a hydrophobic chemical, this challenge was encountered using hydrophilic polyvinylidine difluoride (PVDF) membranes in a biogas reactor. The more sensitive methane-producing archaea were encapsulated in the membranes, while freely suspended digesting bacteria were present in the culture as well. In this membrane bioreactor (MBR), the free digesting bacteria digested the citrus wastes and produced soluble compounds, which could pass through the membrane and converted to biogas by the encapsulated cell. As a control experiment, similar digestions were carried out in bioreactors containing the identical amount of just free cells. The experiments were carried out in thermophilic conditions at 55 °C, and hydraulic retention time of 30 days. The organic loading rate (OLR) was started with 0.3 kg VS/m3/day and gradually increased to 3 kg VS/m3/day. The results show that at the highest OLR, MBR was successful to produce methane at 0.33 Nm3/kg VS, while the traditional free cell reactor reduced its methane production to 0.05 Nm3/kg VS. Approximately 73% of the theoretical methane yield was achieved using the membrane bioreactor. PMID:25167328

Wikandari, Rachma; Millati, Ria; Cahyanto, Muhammad Nur; Taherzadeh, Mohammad J

2014-01-01

93

Biogas project advances in California  

SciTech Connect

The National Renewable Energy Laboratory (NREL) has given a `thumbs up` rating to the high solids anaerobic digester project which is designed to produce biogas. The Sacramento Municipal Utility District (SMUD), the local utility, is considering the use of biogas to run a fuel cell pilot project. The designs for the three digesters are state-of-the-art, with each containing a horizontal trough measuring 120 feet long, 32 feet wide and 22 feet tall. NREL was asked by the PIA to review the mixing method in the digesters and analyze the overall potential success of the operation. The design employs a redundant system for foam removal from the digester gas, and has provisions to remove moisture from the biogas. However, there are no systems specified to reduce hydrogen sulfide levels. Since hydrogen sulfide is known to be corrosive, it may be destructive to the ultimate use as biogas in fuel cells. A suggested remedy from NREL is to add redundant iron sponge systems to remove hydrogen sulfide gases. A redundant system would allow regenerating one while the other is in service. In general, the lab found the design offers low construction costs, relative ease of operation, and a reasonably high level of anticipated success in operation. Therefore, NREL recommends proceeding with the current digester design plans, once the modifications as indicated are made.

Wittrup, L. [Sacramento Municipal Utility District, CA (United States)

1995-04-01

94

Prism sodium-cooled reactor design and performance  

Microsoft Academic Search

The Power Reactor Inherently Safe Module (PRISM) program is being conducted at General Electric (GE) under U.S. Department of Energy sponsorship to develop a conceptual design for an advanced sodium-cooled liquid-metal reactor plant. The PRISM design emphasizes inherent safety, modular construction, and factory fabrication. A PRISM power plant includes a number of reactor modules, which will be fabricated in a

W. Kwant; P. M. Magee; M. R. Patel

1989-01-01

95

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

PubMed

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 ?(13)CH4 and ?(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. PMID:24994682

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

2014-09-01

96

Immobilized cell reactor with simultaneous product separation. II. Experimental reactor performance  

Microsoft Academic Search

The Immobilized Cell Reactor-Separator (ICRS) consists of two column reactors: a cocurrent gas-liquid enricher followed by a countercurrent stripper. The columns are four-phase tubular reactors consisting of 1) an inert gas phase, 2) the liquid fermentation broth, 3) the solid column internal packing, and 4) the immobilized biological catalyst or cells. The application of the ICRS to the ethanol-from-whey-lactose fermentation

M. C. Dale; M. R. Okos; P. C. Wankat

1985-01-01

97

Enhancement of Tokamak Fusion Test Reactor performance by lithium conditioning  

SciTech Connect

Wall conditioning in the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire {ital et} {ital al}., Phys. Plasmas {bold 2}, 2176 (1995)] by injection of lithium pellets into the plasma has resulted in large improvements in deuterium{endash}tritium fusion power production (up to 10.7 MW), the Lawson triple product (up to 10{sup 21} m{sup {minus}3} s keV), and energy confinement time (up to 330 ms). The maximum plasma current for access to high-performance supershots has been increased from 1.9 to 2.7 MA, leading to stable operation at plasma stored energy values greater than 5 MJ. The amount of lithium on the limiter and the effectiveness of its action are maximized through (1) distributing the Li over the limiter surface by injection of four Li pellets into Ohmic plasmas of increasing major and minor radius, and (2) injection of four Li pellets into the Ohmic phase of supershot discharges before neutral-beam heating is begun. {copyright} {ital 1996 American Institute of Physics.}

Mansfield, D.K.; Hill, K.W.; Strachan, J.D.; Bell, M.G.; Scott, S.D.; Budny, R.; Marmar, E.S.; Snipes, J.A.; Terry, J.L.; Batha, S.; Bell, R.E.; Bitter, M.; Bush, C.E.; Chang, Z.; Darrow, D.S.; Ernst, D.; Fredrickson, E.; Grek, B.; Herrmann, H.W.; Janos, A.; Jassby, D.L.; Jobes, F.C.; Johnson, D.W.; Johnson, L.C.; Levinton, F.M.; Mikkelsen, D.R.; Mueller, D.; Owens, D.K.; Park, H.; Ramsey, A.T.; Roquemore, A.L.; Skinner, C.H.; Stevenson, T.; Stratton, B.C.; Synakowski, E.; Taylor, G.; von Halle, A.; von Goeler, S.; Wong, K.L.; Zweben, S.J. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); TFTR Group

1996-05-01

98

Biogas from waste seen as fuel option  

SciTech Connect

Users with access to organic wastes have the option of producing biogas as an alternative fuel. With half the Btu content of natural gas, biogas costs only 40% as much to produce. The anaerobic biogas process results in a 60% methane and 40% carbon dioxide product, which can be used as a boiler fuel to generate power and run equipment or sold to gas utilities for further processing as a pipeline fuel. Transportation costs make ready access to manure or garbage essential. (DCK)

Tucker, L.

1983-01-24

99

Developing a Comprehensive Software Suite for Advanced Reactor Performance and Safety Analysis  

SciTech Connect

This paper provides an introduction to the reactor analysis capabilities of the nuclear power reactor simulation tools that are being developed as part of the U.S. Department of Energy s Nuclear Energy Advanced Modeling and Simulation (NEAMS) Toolkit. The NEAMS Toolkit is an integrated suite of multi-physics simulation tools that leverage high-performance computing to reduce uncertainty in the prediction of performance and safety of advanced reactor and fuel designs. The Toolkit effort is comprised of two major components, the Fuels Product Line (FPL), which provides tools for fuel performance analysis, and the Reactor Product Line (RPL), which provides tools for reactor performance and safety analysis. This paper provides an overview of the NEAMS RPL development effort.

Pointer, William David [ORNL] [ORNL; Bradley, Keith S [ORNL] [ORNL; Fischer, Paul F [ORNL] [ORNL; Smith, Micheal A [ORNL] [ORNL; Tautges, Timothy J [ORNL] [ORNL; Ferencz, Robert M [ORNL] [ORNL; Martineau, Richard C [ORNL] [ORNL; Jain, Rajeev [ORNL] [ORNL; Obabko, Aleksandr [Argonne National Laboratory (ANL)] [Argonne National Laboratory (ANL); Billings, Jay Jay [ORNL] [ORNL

2013-01-01

100

Influence of a three-phase separator configuration on the performance of an upflow anaerobic sludge bed reactor treating wastewater from a fruit-canning factory.  

PubMed

The objective of this study was to investigate the influence of a three-phase separator configuration on the performance of an upflow anaerobic sludge bed (USAB) treating wastewater from a fruit canning factory. The performances of two 30-L UASB reactors--one with a modified three-phase separator giving a spiral flow pattern and the other with a conventional configuration-were investigated in parallel. Wastewater, with a chemical oxygen demand (COD) concentration between 2000 and 7000 mg/L, was obtained from a fruit-canning factory. Based on the effluent data of the first 100 operation days, the UASB with the three-phase separator giving spiral flow patterns yielded up to 25% lower biomass washout. It also showed better efficiencies in treating wastewater--up to 60% lower effluent COD, up to 20% higher COD percent removal, and up to 29% higher biogas production. This work presents evidence of an improvement on the conventional physical design of a UASB. PMID:17370846

Wongnoi, Rachbordin; Songkasiri, Warinthorn; Phalakornkule, Chantaraporn

2007-02-01

101

Advanced-power-reactor design concepts and performance characteristics  

NASA Technical Reports Server (NTRS)

Five reactor cooling concepts which allow continued reactor operation following a single rupture of the coolant system are presented for application with the APR. These concepts incorporate convective cooling, double containment, or heat pipes to ensure operation after a coolant line rupture. Based on an evaluation of several control system concepts, a molybdenum clad, beryllium oxide sliding reflector located outside the pressure vessel is recommended.

Davison, H. W.; Kirchgessner, T. A.; Springborn, R. H.; Yacobucci, H. G.

1974-01-01

102

Investigations for biogas operated MHD power generators  

SciTech Connect

Biogas is produced from the anaerobic fermentation of the organic matter containing cellulose, such as agricultural wastes, human wastes, animal wastes, etc. It contains methane (50-70%), carbon dioxide (30-50%), and very small amounts of hydrogen and hydrogen sulphide. Adequate quantities of raw material to generate biogas are normally available in rural areas, and therefore, there is a possibility that almost all the energy requirements of the rural sector may be fulfilled by biogas. Presently in the rural sector, biogas is used mainly to provide thermal energy (for cooking, etc.), and up to a limited extent, to meet the electrical energy requirements by running electrical generators with engines powered by a mixture of oil and biogas. In this paper, the authors propose a scheme in which biogas can be used to generate electricity more efficiently by using magnetohydrodynamic (MHD) power generators. Investigations have been carried out to make feasibility studies for biogas-operated open cycle MHD power generators. Composition, temperature and electrical conductivity of the seeded (with potassium) combustion products of biogas-air/oxygen systems have been analytically investigated for different percentages of CO/sub 2/ in biogas and at various combustor pressures for a seeding ratio of 1 percent by weight. The effect of preheating and enrichment of air on temperature and electrical conductivity of the seeded combustion plasmas has also been studied.

Dahiya, R.P.; Chand, A.; Sharma, S.C.

1983-12-01

103

Swine lagoon biogas utilization system  

SciTech Connect

A project was conceived to design and build a system to recover methane from pig manure with covered anaerobic lagoon technology. Covered lagoon technology lends itself both to new lagoon construction and to retrofit designs on existing anaerobic lagoons. A two cell passive in-ground digester/lagoon system was designed for a 600 sow feeder pig farm. The digester was covered with a flexible fabric cover made of 30 mil XR-5. The biogas has 1,100 ppm hydrogen sulfide. For the first month of operation 473 cubic feet of biogas per hour has been recovered from the digester 24 hours per day. At this gas flow the engine turns an induction generator to produce 17.1 KW per hour. A little over 80% of the farm`s electrical needs are generated with methane from swine manure. On an annual basis there will be 150,000 KWh of electricity produced from 4.3 million cubic feet of biogas.

Gettier, S.W.; Roberts, M. [Carroll`s Foods of Va., Inc., Waverly, VA (United States)

1994-12-31

104

Recent performance experience with US light water reactor self-actuating safety and relief valves  

SciTech Connect

Over the past several years, there have been a number of operating reactor events involving performance of primary and secondary safety and relief valves in U.S. Light Water Reactors. There are several different types of safety and relief valves installed for overpressure protection of various safety systems throughout a typical nuclear power plant. The following discussion is limited to those valves in the reactor coolant systems (RCS) and main steam systems of pressurized water reactors (PWR) and in the RCS of boiling water reactors (BWR), all of which are self-actuating having a setpoint controlled by a spring-loaded disk acting against system fluid pressure. The following discussion relates some of the significant recent experience involving operating reactor events or various testing data. Some of the more unusual and interesting operating events or test data involving some of these designs are included, in addition to some involving a number of similar events and those which have generic applicability.

Hammer, C.G.

1996-12-01

105

Performance of the Texas cold neutron source at reactor power  

Microsoft Academic Search

The Texas Cold Neutron Source (TCNS) was recently installed into the piercing beam port of the 1-MW TRIGA Mark II research reactor at the Nuclear Engineering Teaching Laboratory of the University of Texas at Austin. The TCNS system consists of a cooled moderator, a neon heat pipe, a cryogenic refrigerator, and a neutron guide. Design features of the TCNS, safety

K. Uenlue; C. Rios-Martinez; T. L. Bauer; B. W. Wehring

1993-01-01

106

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

PubMed

Very recently, it was shown that the addition of acetate or ethanol led to enhanced biogas formation rates during an observation period of 24 h. To determine if increased methane production rates due to ethanol addition can be maintained over longer time periods, continuous reactors filled with biogas sludge were developed which were fed with the same substrates as the full-scale reactor from which the sludge was derived. These reactors are well reflected conditions of a full-scale biogas plant during a period of 14 days. When the fermenters were pulsed with 50-100 mM ethanol, biomethanation increased by 50-150 %, depending on the composition of the biogas sludge. It was also possible to increase methane formation significantly when 10-20 mM pure ethanol or ethanolic solutions (e.g. beer) were added daily. In summary, the experiments revealed that "normal" methane production continued to take place, but ethanol led to production of additional methane. PMID:25344104

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

2014-12-01

107

Pilot-scale chemical-biological system for efficient H2S removal from biogas.  

PubMed

A pilot-scale chemical-biological process was performed efficiently to remove corrosive H2S from biogas. Consecutive 356-d livestock biogas purification was conducted at various H2S loading rates. The average inlet H2S concentration was 3542 ppm, and a removal efficiency of 95% was achieved with gas retention time of 288 s. This system showed robust performance during operation with stable parameters. Purified biogas with an average of 59% CH4 was collected for power production. Moreover, 28.3 kW h of power was produced by using a 30 kW biogas generator under 300 LPM biogas flow rate. During the 30-d shut down test, the jarosite formation resulted in pH decrease and appearance of Leptospirillum sp. and Sulfobacillus sp. in the bioreactor. However, the cell density of the inoculated Acidithiobacillus ferrooxidans was maintained above 5×10(7) CFU/g-AC during long-term operation. Thus, given the successful H2S elimination, the chemical-biological process is a feasible system for biogas purification. PMID:23186660

Lin, Wei-Chih; Chen, Yu-Pei; Tseng, Ching-Ping

2013-05-01

108

RETRACTED ARTICLE: The Evaluation of Reactor Performance by using Flibe and Flinabe Molten Salts in the APEX Hybrid Reactor  

NASA Astrophysics Data System (ADS)

The modeling of APEX hybrid reactor, produced by using ARIES-RS hybrid reactor technology, has been performed by using the MCNP-4B computer code and ENDF/B-V-VI nuclear data. Around the fusion chamber, molten salts Flibe (Li2BeF4) and Flinabe (LiNaBeF4) were used as cooling materials. APEX reactor was modeled in the torus form by adding nuclear materials of low significance in the specified percentages between percent 0-12 to the molten salts. The result of the study indicated that fissile material production, UF4 and ThF4 heavy metal salt increased nearly at the same percentage and it was observed that the percentage of it was practically the same in both materials. In order for the hybrid reactor to work itself in terms of tritium, TBR (tritium breeding ratio) should be lower than 1.05. When flibe molten salt was utilized in the APEX hybrid reactor, TBR was calculated as >1, 22 and when flinabe molten salt was used, TBR was calculated as >1.06.

Korkut, Turgay; Hançerlio?ullar?, Aybaba

2012-04-01

109

Thermal hydraulic performance analysis of a small integral pressurized water reactor core  

E-print Network

A thermal hydraulic analysis of the International Reactor Innovative and Secure (IRIS) core has been performed. Thermal margins for steady state and a selection of Loss Of Flow Accidents have been assessed using three ...

Blair, Stuart R. (Stuart Ryan), 1972-

2003-01-01

110

biogas for rural communities TD390 Supervised learning: Study report  

E-print Network

0 biogas for rural communities TD390 Supervised learning: Study report Vaibhav Nasery Roll No. 08D highly successful rural biogas models wherein biogas is produced and utilized as a cooking fuel by the villagers. The two models studied are the Community Biogas plant established by SUMUL Dairy at Bhintbudrak

Sohoni, Milind

111

Technical\\/economic\\/environmental analysis of biogas utilisation  

Microsoft Academic Search

Biogas may be utilised for Combined Heat and Power (CHP) production or for transport fuel production (CH4-enriched biogas). When used to produce transport fuel either electricity is imported to power the plant or some of the biogas is used in a small CHP unit to meet electricity demand on site. The potential revenue from CH4-enriched biogas when replacing petrol is

J. D. Murphy; E. McKeogh; G. Kiely

2004-01-01

112

Biogas plants in Denmark: technological and economic developments  

Microsoft Academic Search

Biogas plants are one of the important elements in the Danish energy-policy of having reduced CO2 emissions by 20% by 2005. Since 1984, development efforts concerning centralised biogas plants in Denmark have been carried out, and Denmark now has approximately 20 large centralised biogas plants. All Danish biogas plants have increased gas production as a result of admixing industrial organic

H. Mæng; H. Lund; F. Hvelplund

1999-01-01

113

Benefits of supplementing an industrial waste anaerobic digester with energy crops for increased biogas production.  

PubMed

Currently, there is increasing competition for waste as feedstock for the growing number of biogas plants. This has led to fluctuation in feedstock supply and biogas plants being operated below maximum capacity. The feasibility of supplementing a protein/lipid-rich industrial waste (pig manure, slaughterhouse waste, food processing and poultry waste) mesophilic anaerobic digester with carbohydrate-rich energy crops (hemp, maize and triticale) was therefore studied in laboratory scale batch and continuous stirred tank reactors (CSTR) with a view to scale-up to a commercial biogas process. Co-digesting industrial waste and crops led to significant improvement in methane yield per ton of feedstock and carbon-to-nitrogen ratio as compared to digestion of the industrial waste alone. Biogas production from crops in combination with industrial waste also avoids the need for micronutrients normally required in crop digestion. The batch co-digestion methane yields were used to predict co-digestion methane yield in full scale operation. This was done based on the ratio of methane yields observed for laboratory batch and CSTR experiments compared to full scale CSTR digestion of industrial waste. The economy of crop-based biogas production is limited under Swedish conditions; therefore, adding crops to existing industrial waste digestion could be a viable alternative to ensure a constant/reliable supply of feedstock to the anaerobic digester. PMID:21975301

Nges, Ivo Achu; Escobar, Federico; Fu, Xinmei; Björnsson, Lovisa

2012-01-01

114

Accident Performance of Light Water Reactor Cladding Materials  

SciTech Connect

During a loss of coolant accident as experienced at Fukushima, inadequate cooling of the reactor core forces component temperatures ever higher where they must withstand aggressive chemical environments. Conventional zirconium cladding alloys will readily oxidize in the presence of water vapor at elevated temperatures, rapidly degrading and likely failing. A cladding breach removes the critical barrier between actinides and fission products and the coolant, greatly increasing the probability of the release of radioactivity in the event of a containment failure. These factors have driven renewed international interest in both study and improvement of the materials used in commercial light water reactors. Characterization of a candidate cladding alloy or oxidation mitigation technique requires understanding of both the oxidation kinetics and hydrogen production as a function of temperature and atmosphere conditions. Researchers in the MST division supported by the DOE-NE Fuel Cycle Research and Development program are working to evaluate and quantify these parameters across a wide range of proposed cladding materials. The primary instrument employed is a simultaneous thermal analyzer (STA) equipped with a specialized water vapor furnace capable of maintaining temperatures above 1200 C in a range of atmospheres and water vapor contents. The STA utilizes thermogravimetric analysis and a coupled mass spectrometer to measure in situ oxidation and hydrogen production of candidate materials. This capability is unprecedented in study of materials under consideration for reactor cladding use, and is currently being expanded to investigate proposed coating techniques as well as the effect of coating defects on corrosion resistance.

Nelson, Andrew T. [Los Alamos National Laboratory

2012-07-24

115

Life cycle assessment of biogas upgrading technologies.  

PubMed

This article evaluates the life cycle assessment (LCA) of three biogas upgrading technologies. An in-depth study and evaluation was conducted on high pressure water scrubbing (HPWS), as well as alkaline with regeneration (AwR) and bottom ash upgrading (BABIU), which additionally offer carbon storage. AwR and BABIU are two novel technologies that utilize waste from municipal solid waste incinerators - namely bottom ash (BA) and air pollution control residues (APC) - and are able to store CO(2) from biogas through accelerated carbonation processes. These are compared to high pressure water scrubbing (HPWS) which is a widely used technology in Europe. The AwR uses an alkaline solution to remove the CO(2) and then the solution - rich in carbonate and bicarbonate ions - is regenerated through carbonation of APC. The BABIU process directly exposes the gas to the BA to remove and immediately store the CO(2), again by carbonation. It was determined that the AwR process had an 84% higher impact in all LCA categories largely due to the energy intensive production of the alkaline reactants. The BABIU process had the lowest impact in most categories even when compared to five other CO(2) capture technologies on the market. AwR and BABIU have a particularly low impact in the global warming potential category as a result of the immediate storage of the CO(2). For AwR, it was determined that using NaOH instead of KOH improves its environmental performance by 34%. For the BABIU process the use of renewable energies would improve its impact since accounts for 55% of the impact. PMID:22230660

Starr, Katherine; Gabarrell, Xavier; Villalba, Gara; Talens, Laura; Lombardi, Lidia

2012-05-01

116

Fuel processing of biogas for small fuel cell power plants  

NASA Astrophysics Data System (ADS)

Biogas has a huge potential as fuel for fuel cell power plants. In the present work developments in fuel processing of biogas for a phosphoric acid fuel cell power plant to be located in rural India are described. Experimental work including steam reforming and shift conversion of biogas and methane has been carried out in a laboratory development unit. It is confirmed that biogas is not only a useful fuel but also that the carbon dioxide in biogas has a positive effect on methane conversion. The biogas fuel cell power plant will give a high electrical efficiency on the small scale of biogas units.

Thyberg Naumann, Sara; Myrén, Carin

117

Performance of a flat panel reactor in the continuous culture of microalgae in urban wastewater: prediction from a batch experiment.  

PubMed

A laboratory-scale flat panel photobioreactor was operated for the continuous growth of Scenedesmus obliquus and consequent removal of nutrients in wastewater. This study develops a simple model by which biomass values in continuous operation can be predicted from kinetic growth parameters obtained from a shorter batch experiment. Based on this study, biomass concentrations and productivities in continuous operation can be successfully predicted as a function of the specific hydraulic retention time (HRT) assumed. Considerable biomass production and nutrient uptake from wastewater were achieved in the experiment. Optimum operating conditions for the reactor depend on the particular objective: the maximization of biomass production and carbon dioxide biofixation involves a HRT of 2 ?(-1) (specific growth rate), whereas efficient nutrient removal involves a HRT as close as possible to ?(-1) (as long as discharges comply fully with the parameters set); alternatively biomass intended for biodiesel or biogas production would involve a HRT > 2 ?(-1). PMID:23138070

Ruiz, J; Álvarez-Díaz, P D; Arbib, Z; Garrido-Pérez, C; Barragán, J; Perales, J A

2013-01-01

118

Passive solar technology aids biogas digesters  

SciTech Connect

Farming communities throughout China rely on biogas generators as a primary source of light and heat, as well as using the sludge as a nitrogen-rich fertilizer. Now researchers at Beijing's Solar Energy Laboratory have improved efficiency by building a rectangular tank out of concrete slabs, with one slanted surface painted black and covered with glass. According to a report in New Scientist, this passive solar panel generates heat in the same way as a greenhouse, raising inside temperatures by 10{degree}C and increasing biogas production by 50%. Another advantage of the new tanks is easy access, since the tank's lid sites in wells of water which form a seal against oxygen. (Old biogas tanks were made of soil, sand and a little concrete, prone to developing severe cracks which would allow oxygen to enter thus slowing down anaerobic reaction). Explains Debora MacKenzie of New Scientist: with the new tank, the farmer can simply remove the lid and attack the contents with a spade. This means that the mixture can comprise more than 10% solids. Greater density allows smaller tanks. Rural families need one cubic meter of biogas daily for light and heat; instead of the former 8 cm biogas generator, the new tanks need only be 1 cm. The prediction is that the smaller size could make biogas more popular in China's crowded towns. The biogas department is headed by He Shao Qi, who is also investigating ways to reduce production costs for the tanks.

Not Available

1988-07-01

119

Electrode specific information from voltammetric monitoring of biogas production.  

PubMed

A sensor employing pulse voltammetry monitored the liquid phase of a biogas reactor during 32 days of gas production. An electrode array consisting of stainless steel, platinum and rhodium electrodes generated current responses for a sequence of voltage pulses. Plots of individual current responses against time indicated the electrochemical changes occurring in the broth from the perspective of each electrode. The responses from stainless steel had a pronounced diurnal oscillation which followed the daily introduction and consumption of substrate. The current responses for platinum were in a narrow range whereas those for rhodium exhibited several minima. A disturbance in the reactor caused by omission of substrate led to decreases in both gas production and current responses for all the electrodes. Multivariate data evaluation of all the current responses by principal component analysis indicated the daily fluctuations for concentrations of ions and redox active compounds in the broth. PMID:20441942

Bjorklund, Robert B; Christiansson, Anneli; Ek, Anders E W; Ejlertsson, Jörgen

2010-06-15

120

A Framework for Human Performance Criteria for Advanced Reactor Operational Concepts  

SciTech Connect

This report supports the determination of new Operational Concept models needed in support of the operational design of new reactors. The objective of this research is to establish the technical bases for human performance and human performance criteria frameworks, models, and guidance for operational concepts for advanced reactor designs. The report includes a discussion of operating principles for advanced reactors, the human performance issues and requirements for human performance based upon work domain analysis and current regulatory requirements, and a description of general human performance criteria. The major findings and key observations to date are that there is some operating experience that informs operational concepts for baseline designs for SFR and HGTRs, with the Experimental Breeder Reactor-II (EBR-II) as a best-case predecessor design. This report summarizes the theoretical and operational foundations for the development of a framework and model for human performance criteria that will influence the development of future Operational Concepts. The report also highlights issues associated with advanced reactor design and clarifies and codifies the identified aspects of technology and operating scenarios.

Jacques V Hugo; David I Gertman; Jeffrey C Joe

2014-08-01

121

Initial in-reactor performance of the Cornell cold neutron source  

Microsoft Academic Search

The Cornell Cold Neutron Beam Facility consists of two major subsystems, a cold neutron source (CNS) and a 13-m-long curved neutron guide. This paper describes the initial in-reactor performance tests of the CNS. The results agree closely with predictions from out-of-reactor tests and meet the design criteria for safety and simplicity of operation. This phase of the project has therefore

S. A. Spern; D. D. Clark; A. G. Atwood

1996-01-01

122

Performance studies of boron lined proportional counters for reactor applications  

NASA Astrophysics Data System (ADS)

Boron lined proportional counters of standard cylindrical geometry were developed and characterized for reactor applications. It is observed that the life of boron lined proportional counters is significantly lower if irradiated in high neutron flux keeping the HV bias 'ON' compared to the irradiation with HV bias 'OFF'. When operated in gamma radiation, the boron lined proportional counters suffer count rate loss and underestimate the neutron flux. The loss in the count rate in gamma radiation is attributed to the space charge effect. The space charge effect is theoretically calculated for a known gamma radiation. The estimated values compared well with the experimentally observed values. Neutron sensitivity is estimated by modeling the boron lined proportional counters in FLUKA Monte-Carlo simulation code. The estimated neutron sensitivity values are comparable to the experimental and theoretical values.

Dighe, P. M.; Das, D.

2015-01-01

123

The Use of Gas Chromatography for Biogas Analysis  

NASA Astrophysics Data System (ADS)

Energy from natural gas accounts for 24 percent of energy consumed in the US. Natural gas is a robust form of energy which is rich in methane content and is low in impurities. This quality suggests that it is a very clean and safe gas; it can be used in providing heat, a source for cooking, and in powering vehicles. The downside is that it is a non-renewable resource. On the contrary, methane rich gas that is produced by the breakdown of organic material in an anaerobic environment, called biogas, is a renewable energy source. This research focuses on the gas analysis portion of the creation of the anaerobic digestion and verification laboratory where content and forensic analysis of biogas is performed. Gas Chromatography is implemented as the optimal analytical tool for quantifying the components of the biogas including methane, carbon dioxide, hydrogen sulfide and siloxanes. In addition, the problems associated with the undesirable components are discussed. Anaerobic digestion of primary sludge has consistently produced about 55 percent methane; future goals of this research include studying different substrates to increase the methane yield and decrease levels of impurities in the gas.

Andersen, Amanda; Seeley, John; Aurandt, Jennifer

2010-04-01

124

Effect of biogas sparging with different membrane modules on membrane fouling in anaerobic submerged membrane bioreactor (AnSMBR).  

PubMed

This study focused on the effect of biogas sparging and different membrane modules such as cylinder shaped, funnel-shaped, and U-shaped on the membrane fouling behavior in a lab-scale submerged anaerobic membrane bioreactor (AnSMBR) which was operated for over 60 days. In order to investigate the membrane fouling behavior, a series of analysis such as SMP, EPS, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), particle size distribution, and filtration resistances were performed. Although the rapid generation of cake layer took placed in case of the absence of biogas sparging, the membrane module design mostly influenced the membrane resistance when biogas sparging was applied. Total resistance was the highest for U-shaped module. The permeate fluxes with biogas sparging were higher about one half and two times than those without biogas sparging. Cylinder-shaped module had the lowest SMP and EPS concentrations followed by U-shaped and funnel-shaped modules under both cases with and without biogas sparging. The total resistances of all membrane modules without biogas sparging were found to be very high compared the pore blocking resistances (Rp). PMID:24234762

Aslan, Mustafa; Saatçi, Yusuf; Hanay, Özge; Hasar, Halil

2014-03-01

125

Performance analysis and optimization of autotrophic nitrogen removal in different reactor configurations: a modelling study.  

PubMed

The autotrophic nitrogen removal process (partial nitritation combined with the Anammox process) is a new and sustainable nitrogen removal technique for nitrogen-rich streams. A modelling study has been performed to define optimal process conditions (temperature, oxygen supply, pH and biomass retention) and to investigate the influence of chemical oxygen demand, nitrogen loading rate and hydraulic retention time on three alternative reactor configurations: a single oxygen-limited partial nitritation reactor, a single Anammox reactor, and a combination of partial nitritation and Anammox in a single reactor. The model applied was compared to experimental data from the literature and gave good agreement for all three reactor configurations. The simulations revealed that a system with separated partial nitritation and Anammox offered a wider range of optimal process conditions than a one-reactor system. The key factors in the successful operation of partial nitritation were found to be control of aeration, ammonium loading rate and temperature. Heterotrophs remained present in all three reactor systems and it was confirmed that interaction between heterotrophs and Anammox and between heterotrophs and ammonium oxidizers was possible. PMID:21121455

Veys, Pieter; Vandeweyer, Helge; Audenaert, Wim; Monballiu, Annick; Dejans, Pascal; Jooken, Etienne; Dumoulin, Ann; Meesschaert, Boudewijn D; Van Hulle, Stijn W H

2010-11-01

126

Performance of TOF powder diffractometers on reactor sources  

NASA Astrophysics Data System (ADS)

In 1998, a prototype of a time-of-flight (TOF) powder diffractometer was built at KFKI in Budapest in collaboration with the Hahn-Meitner-Institut (HMI) in Berlin. At a reactor source the neutron pulses are produced by a chopper system, which allows for shorter pulses than those obtained at pulsed spallation sources in the wavelength range most relevant for diffraction work, i.e. ??0.7 Å. Furthermore, the chopper system provides an ideal symmetric line shape. First results proved the high potential of the approach, namely an excellent resolution of 1-5×10 -3 for ? d/d was achieved. The prototype is presently rebuilt as a user instrument at the Budapest Neutron Centre. At HMI Berlin a new much more complex TOF powder diffractometer (EXED=extreme environment diffractometer) with higher resolution is under construction. It will benefit from variable resolution to achieve either ultrahigh resolution or very high intensities at conventional resolutions. EXED is devoted to studies under extreme sample conditions, for instance the TOF technique permits the access of a broad range of Q-values or d-spacing domains under scattering angle access strongly restricted by the use of highest field magnets. The whole instrument was simulated by Monte Carlo (MC) technique, and the simulations yield promising results.

Peters, Judith; Bleif, Hans-Jürgen; Kali, György; Rosta, Laszlo; Mezei, Ferenc

2006-11-01

127

Quantifying temperature and flow rate effects on the performance of a fixed-bed chromatographic reactor.  

PubMed

Chromatographic reactors are based on coupling chemical reactions with chromatographic separation in fixed-beds. Temperature and flow rate are important parameters for the performance of such reactors. Temperature affects mainly adsorption, chemical equilibria, mass transfer and reaction kinetics, whereas flow rate influences residence time and dispersion. In order to evaluate the mentioned effects, the hydrolysis reactions of methyl formate (MF) and methyl acetate (MA) were chosen as case studies. These reactions were performed experimentally in a lab-scale fixed-bed chromatographic reactor packed with a strong acidic ion exchange resin. The chosen reactions can be considered to represent a relative fast (MF) and a relative slow (MA) reaction. The processes which take place inside the reactor were described and simulated using an isothermal equilibrium dispersive model. The essential model parameters were determined experimentally at different temperatures and flow rates. The performance of the chromatographic reactor was evaluated at several discrete constant temperature levels by quantifying product purity, productivity and yield. The work provides insight regarding the influence of temperature and flow rate on values of the model parameters and the performance criteria. PMID:21963179

Vu, Tien D; Seidel-Morgenstern, A

2011-11-01

128

Performance testing of refractory alloy-clad fuel elements for space reactors  

NASA Astrophysics Data System (ADS)

Two fast reactor irradiation tests, SP-1 and SP-2, provide a unique and self-consistent data set with which to evaluate the technical feasibility of potential fuel systems for the SP-100 space reactor. Fuel pins fabricated with leading cladding candidates (Nb-1Zr, PWC-11, and Mo-13Re) and fuel forms (UN and UO2) are operated at temperatures typical of those expected in the SP-100 design. The first US fast reactor irradiated, refractory alloy clad fuel pins, from the SP-1 test, reached 1 at. % burnup in EBR-II in March 1985. At that time selected pins were discharged for interim examination. These examinations confirmed the excellent performance of the Nb-1Zr clad uranium oxide and uranium nitride fuel elements, which are the baseline fuel systems for two SP-100 reactor concepts.

Dutt, D. S.; Cox, C. M.; Karnesky, R. A.; Millhollen, M. K.

129

Fuel performance models for high-temperature gas-cooled reactor core design  

SciTech Connect

Mechanistic fuel performance models are used in high-temperature gas-cooled reactor core design and licensing to predict failure and fission product release. Fuel particles manufactured with defective or missing SiC, IPyC, or fuel dispersion in the buffer fail at a level of less than 5 x 10/sup -4/ fraction. These failed particles primarily release metallic fission products because the OPyC remains intact on 90% of the particles and retains gaseous isotopes. The predicted failure of particles using performance models appears to be conservative relative to operating reactor experience.

Stansfield, O.M.; Simon, W.A.; Baxter, A.M.

1983-09-01

130

Reviewing real-time performance of nuclear reactor safety systems  

SciTech Connect

The purpose of this paper is to recommend regulatory guidance for reviewers examining real-time performance of computer-based safety systems used in nuclear power plants. Three areas of guidance are covered in this report. The first area covers how to determine if, when, and what prototypes should be required of developers to make a convincing demonstration that specific problems have been solved or that performance goals have been met. The second area has recommendations for timing analyses that will prove that the real-time system will meet its safety-imposed deadlines. The third area has description of means for assessing expected or actual real-time performance before, during, and after development is completed. To ensure that the delivered real-time software product meets performance goals, the paper recommends certain types of code-execution and communications scheduling. Technical background is provided in the appendix on methods of timing analysis, scheduling real-time computations, prototyping, real-time software development approaches, modeling and measurement, and real-time operating systems.

Preckshot, G.G. [Lawrence Livermore National Lab., CA (United States)

1993-08-01

131

Strategies for optimizing recovery of the biogas process following ammonia inhibition  

Microsoft Academic Search

Strategies for recovery of ammonia-inhibited thermophilic biogas process, were evaluated in batch and lab-scale reactors. Active methane producing biomass (digested cattle manure) was inhibited with NH4Cl and subsequently, 3–5 days later, diluted with 50% of water, or with 50% digested manure, or with 50% fresh manure or kept undiluted. Dilution with fresh cattle manure resulted in the highest methane production

Henrik Bangsø Nielsen; Irini Angelidaki

2008-01-01

132

Selection of appropriate fuel processor for biogas-fuelled SOFC system  

Microsoft Academic Search

The performance of biogas-fed solid oxide fuel cell (SOFC) systems utilizing different reforming agents (steam, air and combined air\\/steam) has been investigated via thermodynamic analysis to determine the most suitable feed. The boundary of carbon formation was first calculated to specify the minimum amount of each reforming agent necessary to avoid carbon formation. The SOFC performance (electrical efficiency and power

P. Piroonlerkgul; S. Assabumrungrat; N. Laosiripojana; A. A. Adesina

2008-01-01

133

Influence of partial wetting on trickle-bed reactor performance  

E-print Network

was studied by varying the liquid flow rate while keeping the gasito-liquid ratio constan4 along with the space velocity. Thus, any change in the exi4 conversion should be due to changes in the wetting efficiency. The hydrogenation reaction of biphenyl over... a nickel/molybdenum catalyst was used as a model reaction. All experiments were performed al, 296 'C and 5. 2 MPa. Experimental resul4s show that the conversion increases with gas and liquid flow rates at constan4 space velocity. This suggests...

Ruecker, Craig Michael

1985-01-01

134

Performance and Safety Analysis of a Generic Small Modular Reactor  

E-print Network

the publically available performance criteria of the mPower SMR from B&W. The Monte Carlo codes MCNP5/MCNPX are used to model the core. Fuel enrichment, core inventory, core size are all variables optimized to meet the set goals of core lifetime and fuel... utilization (burnup). Vital core behavior characteristics such as delayed neutron fraction and reactivity coefficients are calculated and shown to be typical of larger PWR systems, which is necessary to ensure the inherent safety and to achieve rapid...

Kitcher, Evans Damenortey, 1987-

2012-11-07

135

Compressed biogas at the Christchurch Drainage Board. Final report  

SciTech Connect

Experience of the Christchurch Drainage Board in using biogas for fueling a part of its transport fleet is described. The experience is documented and benefits to other potential users of biogas are demonstrated.

Not Available

1986-04-01

136

Effect of liquid properties on the performance of bubble column reactors with fine pore spargers  

Microsoft Academic Search

This work is a study of the effect of liquid properties on the performance of bubble column reactors with fine pore spargers. Various liquids covering a range of surface tension and viscosity values are employed, while the gas phase is atmospheric air. A fast video technique is used for visual observations and, combined with image processing, is used for gas

A. A. Mouza; G. K. Dalakoglou; S. V. Paras

2005-01-01

137

Influence of total solid and inoculum contents on performance of anaerobic reactors treating food waste  

Microsoft Academic Search

The aim of this paper was to analyze the biomethanization process of food waste (FW) from a university campus restaurant in six reactors with three different total solid percentages (20%, 25% and 30% TS) and two different inoculum percentages (20–30% of mesophilic sludge). The experimental procedure was programmed to select the initial performance parameters (total solid and inoculum contents) in

T. Forster-Carneiro; M. Pérez; L. I. Romero

2008-01-01

138

Choosing co-substrates to supplement biogas production from animal slurry--a life cycle assessment of the environmental consequences.  

PubMed

Biogas production from animal slurry can provide substantial contributions to reach renewable energy targets, yet due to the low methane potential of slurry, biogas plants depend on the addition of co-substrates to make operations profitable. The environmental performance of three underexploited co-substrates, straw, organic household waste and the solid fraction of separated slurry, were assessed against slurry management without biogas production, using LCA methodology. The analysis showed straw, which would have been left on arable fields, to be an environmentally superior co-substrate. Due to its low nutrient content and high methane potential, straw yields the lowest impacts for eutrophication and the highest climate change and fossil depletion savings. Co-substrates diverted from incineration to biogas production had fewer environmental benefits, due to the loss of energy production, which is then produced from conventional fossil fuels. The scenarios can often provide benefits for one impact category while causing impacts in another. PMID:25226057

Croxatto Vega, Giovanna Catalina; ten Hoeve, Marieke; Birkved, Morten; Sommer, Sven G; Bruun, Sander

2014-11-01

139

Effect of Different Structural Materials on Neutronic Performance of a Hybrid Reactor  

NASA Astrophysics Data System (ADS)

Selection of structural material for a fusion-fission (hybrid) reactor is very important by taking into account of neutronic performance of the blanket. Refractory metals and alloys have much higher operating temperatures and neutron wall load (NWL) capabilities than low activation materials (ferritic/martensitic steels, vanadium alloys and SiC/SiC composites) and austenitic stainless steels. In this study, effect of primary candidate refractory alloys, namely, W-5Re, T111, TZM and Nb-1Zr on neutronic performance of the hybrid reactor was investigated. Neutron transport calculations were conducted with the help of SCALE 4.3 System by solving the Boltzmann transport equation with code XSDRNPM. Among the investigated structural materials, tantalum had the worst performance due to the fact that it has higher neutron absorption cross section than others. And W-5Re and TZM having similar results showed the best performance.

Übeyli, Mustafa; Tel, Eyyüp

2003-06-01

140

Biogas cleans up its act  

SciTech Connect

The development of waste-composting facilities and anaerobic waste-treatment plants, which produce smaller volumes of cleaner gas than landfills, has caused companies to reexamine how methane-rich offgas streams are handled. Now, biogas producers are beginning to extract further value from the methane, mainly by cleaning the gas to allow it to be fed to the growing natural-gas grids in the US and Europe. Another value-added route is to clean and boost the gas pressure to 250 bars for use as a fuel in compressed natural gas (CNG) vehicles. Depending on the volume and concentration of contaminants, absorption, carbon adsorption, biofilters, membrane separation, iron-based scavengers and wet oxidation are the principal clean-up routes being pursued. For high flowrates and sulfur loadings in excess o 500 lb/d, liquid oxidation or scavenger-based schemes are the most economic approaches. For lower volumes, however, liquid scrubbing, carbon adsorption and biofilters are more promising. These systems are discussed.

Fouhy, K.; Shelley, S.

1997-05-01

141

Biogas electricity -- The Pura village case study  

SciTech Connect

A potentially useful decentralized source of energy is biogas, which is an approximately 60:40 mixture of methane (CH{sub 4}) and carbon dioxide (CO{sub 2}), produced by the anaerobic fermentation of cellulosic biomass materials such as bovine wastes. Since 1987, the traditional system of obtaining water, illumination, and fertilizer in Pura village in south India has been replaced with a community biogas plant electricity-generation system. The technical, managerial, and economical aspects of this system are the subject manner of the present paper. Various subsystems are described, and the problems of operation and maintenance under field conditions are also discussed. A comparison of Pura`s present community biogas system with its traditional means for obtaining water, illumination, and fertilizer shows that the households are winners on all counts, having obtained such benefits as improved hygiene and convenience at relatively low cost. The Pura community biogas plant is held together and sustained by the convergence of individual and collective interests. Noncooperation with the community biogas plant results in a heavy individual price (access to water and light being cut off by the village), which is too great a personal loss to compensate for the minor advantages of noncooperation and noncontribution to collective interests.

Rajabapaiah, P.; Jayakumar, S. [Indian Inst. of Science, Bangalore (India); Reddy, A.K.N. [International Energy Initiative, Bangalore (India)

1993-12-31

142

5. oktober 2009 Precision control of biogas plants  

E-print Network

5. oktober 2009 Precision control of biogas plants Final report Henrik B. Møller, Anders M. Nielsen: "Precision control of biogas plants", J. Nr. 33031-0028, funded by EUDP 2005. The final report consists. Danish summary of the results: Det har været formålet at udvikle drift og design af biogas anlæg med

143

The good, the bad or the ugly: Microbial biomass of biogas residues as a contributor to soil carbon cycle  

NASA Astrophysics Data System (ADS)

Loss of soil organic matter is a recent problem in soils all over the world. This can be related to enhanced mineralization of the soil organic matter due to land use change, which is a source of anthropogenic carbon dioxide increase. For example, the carbon input from plant residues is reduced because of the increased cultivation of bioenergy crops. In order to avoid soil degradation, application of biogas residues is a common practice in such areas. Biogas residues are side products of biogas production and contain microbial biomass. Application of these residues as soil additive influences the soil microorganisms as well as the carbon cycle. We study this effect by incubating 13C-labeled biogas residues in an arable soil from the Static Fertilization Experiment in Bad Lauchstaedt, Germany. Labeled residues were produced via labeling of active microbial biomass by addition of KH13CO3 to biogas reactors. High enrichment in the various phospholipid fatty acids proved the successful labeling of the biomass. The labeled biogas residues are being long-term incubated in the soil. During incubation, we monitor the fate of the carbon by analyzing the label in phospholipid fatty acids, amino acids as well as carbon dioxide. This allows us to trace the fate of the biogas residues-derived C in soil and to quantify the effect on the transformation of the natural soil organic matter (e.g. negative effects such as priming effects). Also, microbial community dynamics will be determined using molecular biology tools such as denaturing gradient gel electrophoresis (DGGE) and real-time quantitative PCR (Q-PCR). In order to prevent potentially negative effects, various additives such as charred biomaterials, clays and chopped bark will be tested to improve the carbon storage in soil. In conclusion, this study investigates the fate and impact of biogas residues used as a soil additive on the soil microbial community and amount of soil organic matter. It is aimed to understand and clarify whether the biogas residues play the good, the bad or just the ugly in soil carbon cycling. Thus, recommendations about the use of biogas residues as fertilizers or soil additives in agriculture will be contributed. Furthermore, the data will be a potential input to a landscape generator model which will predict soil quality development in Central Germany.

Coban, H.; Miltner, A.; Kaestner, M.

2013-12-01

144

Dynamic biogas upgrading based on the Sabatier process: Thermodynamic and dynamic process simulation.  

PubMed

This study aimed to investigate the feasibility of substitute natural gas (SNG) generation using biogas from anaerobic digestion and hydrogen from renewable energy systems. Using thermodynamic equilibrium analysis, kinetic reactor modeling and transient simulation, an integrated approach for the operation of a biogas-based Sabatier process was put forward, which was then verified using a lab scale heterogenous methanation reactor. The process simulation using a kinetic reactor model demonstrated the feasibility of the production of SNG at gas grid standards using a single reactor setup. The Wobbe index, CO2 content and calorific value were found to be controllable by the H2/CO2 ratio fed the methanation reactor. An optimal H2/CO2 ratio of 3.45-3.7 was seen to result in a product gas with high calorific value and Wobbe index. The dynamic reactor simulation verified that the process start-up was feasible within several minutes to facilitate surplus electricity use from renewable energy systems. PMID:25453430

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

2015-02-01

145

Modelling biogas production of solid waste: application of the BGP model to a synthetic landfill  

NASA Astrophysics Data System (ADS)

Production of biogas as a result of the decomposition of organic matter included on solid waste landfills is still an issue to be understood. Reports on this matter are rarely included on the engineering construction projects of solid waste landfills despite it can be an issue of critical importance while operating the landfill and after its closure. This paper presents an application of BGP (Bio-Gas-Production) model to a synthetic landfill. The evolution in time of the concentrations of the different chemical compounds of biogas is studied. Results obtained show the impact on the air quality of different management alternatives which are usually performed in real landfills.

Rodrigo-Ilarri, Javier; Segura-Sobrino, Francisco

2013-04-01

146

Development of an Integrated Performance Model for TRISO-Coated Gas Reactor Particle Fuel  

SciTech Connect

The success of gas reactors depends upon the safety and quality of the coated particle fuel. The understanding and evaluation of this fuel requires development of an integrated mechanistic fuel performance model that fully describes the mechanical and physico-chemical behavior of the fuel particle under irradiation. Such a model, called PARFUME (PARticle Fuel ModEl), is being developed at the Idaho National Engineering and Environmental Laboratory. PARFUME is based on multi-dimensional finite element modeling of TRISO-coated gas reactor fuel. The goal is to represent all potential failure mechanisms and to incorporate the statistical nature of the fuel. The model is currently focused on carbide, oxide nd oxycarbide uranium fuel kernels, while the coating layers are the classical IPyC/SiC/OPyC. This paper reviews the current status of the mechanical aspects of the model and presents results of calculations for irradiations from the New Production Modular High Temperature Gas Reactor program.

Petti, David Andrew; Miller, Gregory Kent; Martin, David George; Maki, John Thomas

2005-05-01

147

Comparative analysis of environmental impacts of maize-biogas and photovoltaics on a land use basis  

SciTech Connect

This study aims to stimulate the discussion on how to optimize a sustainable energy mix from an environmental perspective and how to apply existing renewable energy sources in the most efficient way. Ground-mounted photovoltaics (PV) and the maize-biogas-electricity route are compared with regard to their potential to mitigate environmental pressure, assuming that a given agricultural area is available for energy production. Existing life cycle assessment (LCA) studies are taken as a basis to analyse environmental impacts of those technologies in relation to conventional technology for power and heat generation. The life-cycle-wide mitigation potential per area used is calculated for the impact categories non-renewable energy input, green house gas (GHG) emissions, acidification and eutrophication. The environmental performance of each system depends on the scenario that is assumed for end energy use (electricity and heat supply have been contemplated). In all scenarios under consideration, PV turns out to be superior to biogas in almost all studied impact categories. Even when maize is used for electricity production in connection with very efficient heat usage, and reduced PV performance is assumed to account for intermittence, PV can still mitigate about four times the amount of green house gas emissions and non-renewable energy input compared to maize-biogas. Soil erosion, which can be entirely avoided with PV, exceeds soil renewal rates roughly 20-fold on maize fields. Regarding the overall Eco-indicator 99 (H) score under most favourable assumptions for the maize-biogas route, PV has still a more than 100% higher potential to mitigate environmental burden. At present, the key advantages of biogas are its price and its availability without intermittence. In the long run, and with respect to more efficient land use, biogas might preferably be produced from organic waste or manure, whereas PV should be integrated into buildings and infrastructures. (author)

Graebig, Markus; Fenner, Richard [Centre for Sustainable Development, Department of Engineering, University of Cambridge (United Kingdom); Bringezu, Stefan [Wuppertal Institute for Climate, Environment and Energy. P.B. 100480, 42004 Wuppertal (Germany)

2010-07-15

148

Performance evaluation of a continuous flow photocatalytic reactor for wastewater treatment.  

PubMed

A novel photocatalytic reactor for wastewater treatment was designed and constructed. The main part of the reactor was an aluminum tube in which 12 stainless steel circular baffles and four quartz tube were placed inside of the reactor like shell and tube heat exchangers. Four UV-C lamps were housed within the space of the quartz tubes. Surface of the baffles was coated with TiO2. A simple method was employed for TiO2 immobilization, while the characterization of the supported photocatalyst was based on the results obtained through performing some common analytical methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), and BET. Phenol was selected as a model pollutant. A solution of a known initial concentration (20, 60, and 100 ppmv) was introduced to the reactor. The reactor also has a recycle flow to make turbulent flow inside of the reactor. The selected recycle flow rate was 7?×?10(-5) m(3).s(-1), while the flow rate of feed was 2.53?×?10(-7), 7.56?×?10(-7), and 1.26?×?10(-6) m(3).s(-1), respectively. To evaluate performance of the reactor, response surface methodology was employed. A four-factor three-level Box-Behnken design was developed to evaluate the reactor performance for degradation of phenol. Effects of phenol inlet concentration (20-100 ppmv), pH (3-9), liquid flow rate (2.53?×?10(-7)-1.26?×?10(-6) m(3).s(-1)), and TiO2 loading (8.8-17.6 g.m(-2)) were analyzed with this method. The adjusted R (2) value (0.9936) was in close agreement with that of corresponding R (2) value (0.9961). The maximum predicted degradation of phenol was 75.50 % at the optimum processing conditions (initial phenol concentration of 20 ppmv, pH???6.41, and flow rate of 2.53?×?10(-7) m(3).s(-1) and catalyst loading of 17.6 g.m(-2)). Experimental degradation of phenol determined at the optimum conditions was 73.7 %. XRD patterns and SEM images at the optimum conditions revealed that crystal size is approximately 25 nm and TiO2 nanoparticles with visible agglomerates distribute densely and uniformly over the surface of stainless steel substrate. BET specific surface area of immobilized TiO2 was 47.2 and 45.8 m(2) g(-1) before and after the experiments, respectively. Reduction in TOC content, after steady state condition, showed that maximum phenol decomposition occurred at neutral condition (pH???6). PMID:24946704

Rezaei, Mohammad; Rashidi, Fariborz; Royaee, Sayed Javid; Jafarikojour, Morteza

2014-11-01

149

Staged and non-staged anaerobic filters: microbial activity segregation, hydrodynamic behaviour and performance  

Microsoft Academic Search

This work describes a comparative study of staged and non-staged anaerobic -lters for treating a synthetic dairy waste under similar operating con- ditions. The e†ect of increasing the substrate concentration from 3 to 12 g COD dm~3 at a constant hydraulic residence time (HRT) of 2 days was evaluated with respect to overall reactor performance, biogas production, volatile fatty acids

Madalena Alves; Alcina Pereira; Manuel Mota; M. Novais; Emer Colleran

1998-01-01

150

Renewable Hydrogen Potential from Biogas in the United States  

SciTech Connect

This analysis updates and expands upon previous biogas studies to include total potential and net availability of methane in raw biogas with respect to competing demands and includes a resource assessment of four sources of biogas: (1) wastewater treatment plants, including domestic and a new assessment of industrial sources; (2) landfills; (3) animal manure; and (4) a new assessment of industrial, institutional, and commercial sources. The results of the biogas resource assessment are used to estimate the potential production of renewable hydrogen from biogas as well as the fuel cell electric vehicles that the produced hydrogen might support.

Saur, G.; Milbrandt, A.

2014-07-01

151

Biogas production potential from cotton wastes  

Microsoft Academic Search

The anaerobic treatability and methane generation potential of three different cotton wastes namely, cotton stalks, cotton seed hull and cotton oil cake were determined in batch reactors. In addition, the effects of nutrient and trace metal supplementation were also investigated. To this purpose biochemical methane potential (BMP) experiments were performed for two different waste concentrations, namely 30 and 60g\\/l. The

A. Isci; G. N. Demirer

2007-01-01

152

Improvement of membrane performances to enhance the yield of vanillin in a pervaporation reactor.  

PubMed

In membrane reactors, the interaction of reaction and membrane separation can be exploited to achieve a "process intensification", a key objective of sustainable development. In the present work, the properties that the membrane must have to obtain this result in a pervaporation reactor are analyzed and discussed. Then, the methods to enhance these properties are investigated for the photocatalytic synthesis of vanillin, which represents a case where the recovery from the reactor of vanillin by means of pervaporation while it is produced allows a substantial improvement of the yield, since its further oxidation is thus prevented. To this end, the phenomena that control the permeation of both vanillin and the reactant (ferulic acid) are analyzed, since they ultimately affect the performances of the membrane reactor. The results show that diffusion of the aromatic compounds takes place in the presence of low concentration gradients, so that the process is controlled by other phenomena, in particular by the equilibrium with the vapor at the membrane-permeate interface. On this basis, it is demonstrated that the performances are enhanced by increasing the membrane thickness and/or the temperature, whereas the pH begins to limit the process only at values higher than 6.5. PMID:24957123

Camera-Roda, Giovanni; Cardillo, Antonio; Loddo, Vittorio; Palmisano, Leonardo; Parrino, Francesco

2014-01-01

153

Process for electric power production using a biogas  

SciTech Connect

A process is described for the production of electric power with a biogas used as a fuel for an electric power producing combustion turbine which drives a generator. The turbine will accept such a biogas only at a temperature below a predetermined temperature, wherein a biomass is gasified to produce a hot stream of a biogas. The biogas is at temperatures of between about 650/sup 0/-875/sup 0/C and contains vaporized tar components and solid particulate matter. It is characterized in that: the hot stream of biogas, consisting essentially of a biogas, vaporized tars and solid particulate matter, has water injected thereto partially cool the biogas to a temperature below the predetermined temperature by vaporization of the water. However, the biogas is above a temperature at which the vaporized tars in the biogas would condense out of the stream; filtering the partially cooled biogas to remove the particulate matter; and directly charging the partially cooled, filtered biogas containing the vaporized water and vaporized tars to an electric power producing combustion turbine to produce electric power.

Archer, D.H.; Bauer, F.I.; Vidt, E.J.

1987-01-27

154

High-rate hydrogenotrophic methanogenesis for biogas upgrading: the role of anaerobic granules.  

PubMed

Hydrogenotrophic methanogenesis has been proved to be a feasible biological method for biogas upgrading. To improve its performance, the feasibility of typical anaerobic granules as the inoculum was investigated in both batch and continuous experiments. The results from batch experiments showed that glucose-acclimated granules seemed to perform better than granules acclimated to acidified products (AP, i.e. acetate, propionate and ethanol) in in situ biogas upgrading systems and a slightly higher H2 consumption rate (1.5?mmol H2?g VSS(-1)?h(-1)) was obtained for glucose-acclimated granules. For AP-acclimated granules, the inhibition on anaerobic digestion and pH increase (up to 9.55±0.16) took place, and the upgrading performance was adversely affected. In contrast, better performance for AP-acclimated granules was observed in ex situ systems, possibly due to their higher hydrogenotrophic methanogenic activities (HMA). Moreover, when gas-liquid mass transfer limitations were alleviated, the upgrading performance was significantly improved (three-fold) for both glucose-acclimated and AP-acclimated granules. The HMA of anaerobic granules could be further enhanced to improve biogas upgrading performance via continuous cultivation with H2/CO2 as the sole substrate. During the three months' cultivation, secondary granulation and microbial population shift were observed, but anaerobic granules still remained intact and their HMA increased from 0.2 to 0.6?g COD?g VSS(-1)?d(-1). It indicated that the formation of hydrogenotrophic methanogenic granules, a new type of anaerobic granules specialized for high-rate hydrogenotrophic methanogenesis and biogas upgrading, might be possible. Conclusively, anaerobic granules showed great potential for biogas upgrading. PMID:25347307

Xu, Heng; Gong, Shufen; Sun, Yuanzi; Ma, Hailing; Zheng, Mingyue; Wang, Kaijun

2015-02-01

155

Effects of steam pretreatment and co-production with ethanol on the energy efficiency and process economics of combined biogas, heat and electricity production from industrial hemp  

PubMed Central

Background The study presented here has used the commercial flow sheeting program Aspen Plus™ to evaluate techno-economic aspects of large-scale hemp-based processes for producing transportation fuels. The co-production of biogas, district heat and power from chopped and steam-pretreated hemp, and the co-production of ethanol, biogas, heat and power from steam-pretreated hemp were analysed. The analyses include assessments of heat demand, energy efficiency and process economics in terms of annual cash flows and minimum biogas and ethanol selling prices (MBSP and MESP). Results Producing biogas, heat and power from chopped hemp has the highest overall energy efficiency, 84% of the theoretical maximum (based on lower heating values), providing that the maximum capacity of district heat is delivered. The combined production of ethanol, biogas, heat and power has the highest energy efficiency (49%) if district heat is not produced. Neither the inclusion of steam pretreatment nor co-production with ethanol has a large impact on the MBSP. Ethanol is more expensive to produce than biogas is, but this is compensated for by its higher market price. None of the scenarios examined are economically viable, since the MBSP (EUR 103–128 per MWh) is higher than the market price of biogas (EUR 67 per MWh). The largest contribution to the cost is the cost of feedstock. Decreasing the retention time in the biogas process for low solids streams by partly replacing continuous stirred tank reactors by high-rate bioreactors decreases the MBSP. Also, recycling part of the liquid from the effluent from anaerobic digestion decreases the MBSP. The production and prices of methane and ethanol influence the process economics more than the production and prices of electricity and district heat. Conclusions To reduce the production cost of ethanol and biogas from biomass, the use of feedstocks that are cheaper than hemp, give higher output of ethanol and biogas, or combined production with higher value products are primarily suggested. Further, practical investigations on increased substrate concentration in biogas and ethanol production, recycling of the liquid in anaerobic digestion and separation of low solids flows into solid and a liquid fraction for improved reactor applications deserves further attention. PMID:23607263

2013-01-01

156

Analysis of bacterial communities and bacterial pathogens in a biogas plant by the combination of ethidium monoazide, PCR and Ion Torrent sequencing.  

PubMed

The present study investigated the changes of bacterial community composition including bacterial pathogens along a biogas plant, i.e. from the influent, to the biogas reactor and to the post-digester. The effects of post-digestion temperature and time on the changes of bacterial community composition and bacterial pathogens were also studied. Microbial analysis was made by Ion Torrent sequencing of the PCR amplicons from ethidium monoazide treated samples, and ethidium monoazide was used to cleave DNA from dead cells and exclude it from PCR amplification. Both similarity and taxonomic analysis showed that the bacterial community composition in the influent was changed after anaerobic digestion. Firmicutes were dominant in all the samples, while Proteobacteria decreased in the biogas reactor compared with the influent. Variations of bacterial community composition in the biogas reactor with time were also observed. This could be attributed to varying composition of the influent. Batch experiments showed that the methane recovery from the digested residues (obtained from biogas reactor) was mainly related with post-digestion temperature. However, post-digestion time rather than temperature had a significant effect on the changes of bacterial community composition. The changes of bacterial community composition were also reflected in the changes of relative abundance of bacterial pathogens. The richness and relative abundance of bacterial pathogens were reduced after anaerobic digestion in the biogas reactor. It was found in batch experiments that bacterial pathogens showed the highest relative abundance and richness after 30 days' post-digestion. Streptococcus bovis was found in all the samples. Our results showed that special attention should be paid to the post-digestion since the increase in relative abundance of bacterial pathogens after post-digestion might reflect regrowth of bacterial pathogens and limit biosolids disposal vectors. PMID:24852413

Luo, Gang; Angelidaki, Irini

2014-09-01

157

Performance analysis of a mixed nitride fuel system for an advanced liquid metal reactor  

SciTech Connect

The conceptual development and analysis of a proposed mixed nitride driver and blanket fuel system for a prototypic advanced liquid metal reactor design has been performed. As a first step, an intensive literature survey was completed on the development and testing of nitride fuel systems. Based on the results of this survey, prototypic mixed nitride fuel and blanket pins were designed and analyzed using the SIEX computer code. The analysis predicted that the nitride fuel consistently operated at peak temperatures and cladding strain levels that compared quite favorably with competing fuel designs. These results, along with data available in the literature on nitride fuel performance, indicate that a nitride fuel system should offer enhanced capabilities for advanced liquid metal reactors. 13 refs., 10 figs., 2 tabs.

Lyon, W.F.; Baker, R.B.; Leggett, R.D.

1990-11-01

158

Analysis of dashpot performance for rotating control drums of a lithium cooled fast reactor concept  

NASA Technical Reports Server (NTRS)

A dashpot was incorporated in the design of the drive train of the rotating control drum to prevent shock damage to the control drum and drive train at the termination of a scram action. A rotating vane dashpot using reactor coolant lithium as a damping fluid appears to be the best candidate of the various damping devices explored. A performance analysis, results and discussion of vane type dashpots are presented.

Wenzler, C. J.

1972-01-01

159

Performance of molybdenum with UF 4 at high temperatures as a wall material for space reactors  

Microsoft Academic Search

Thin 99.99 pct purity molybdenum (Mo) foils for use in gas core reactors have been tested in both liquid and gaseous uranium\\u000a tetrafluoride (UF4) at temperature ranges of 1500 to 2000 K under argon pressures approaching 600 torr for exposure times of 15 to 75 minutes.\\u000a Weight change measurements have been performed before and after the experiments. Surface and cross-sectional

Z. E. Erkmen; S. Anghaie

1997-01-01

160

Biogas production: current state and perspectives.  

PubMed

Anaerobic digestion of energy crops, residues, and wastes is of increasing interest in order to reduce the greenhouse gas emissions and to facilitate a sustainable development of energy supply. Production of biogas provides a versatile carrier of renewable energy, as methane can be used for replacement of fossil fuels in both heat and power generation and as a vehicle fuel. For biogas production, various process types are applied which can be classified in wet and dry fermentation systems. Most often applied are wet digester systems using vertical stirred tank digester with different stirrer types dependent on the origin of the feedstock. Biogas is mainly utilized in engine-based combined heat and power plants, whereas microgas turbines and fuel cells are expensive alternatives which need further development work for reducing the costs and increasing their reliability. Gas upgrading and utilization as renewable vehicle fuel or injection into the natural gas grid is of increasing interest because the gas can be used in a more efficient way. The digestate from anaerobic fermentation is a valuable fertilizer due to the increased availability of nitrogen and the better short-term fertilization effect. Anaerobic treatment minimizes the survival of pathogens which is important for using the digested residue as fertilizer. This paper reviews the current state and perspectives of biogas production, including the biochemical parameters and feedstocks which influence the efficiency and reliability of the microbial conversion and gas yield. PMID:19777226

Weiland, Peter

2010-01-01

161

Biogas plants in Denmark: successes and setbacks  

Microsoft Academic Search

With 20 centralised plants and over 35 farmscale plants, the digestion of manure and organic waste is a well established technological practice in Denmark. These plants did not emerge without a struggle. Moreover, no new centralised plants have been established since 1998 and the development of farmscale plants has slowed down. This article reviews the experimental introduction of biogas plants

R. P. J. M. Raven; K. H. Gregersen

2007-01-01

162

The optimal size for biogas plants  

Microsoft Academic Search

The costs of biogas and electricity production from maize silage in relation to plant size are investigated in this paper. A survey of manufacturers’ engineering data was conducted to derive a reliable relationship between the capacity of a combined heat and power (CHP) unit and its electrical efficiency. Then a model was developed to derive cost curves for the unit

C. Walla; W. Schneeberger

2008-01-01

163

Team Bug Bag Biogas For Nicaragua  

E-print Network

Team Bug Bag Biogas For Nicaragua Project Recap The task for Team Bug Bag was to create three times a day. In order to achieve this task, Team Bug Bag researched multiple different types customer needs and analyzing the external research, Team Bug Bag created a batch anaerobic digester

Demirel, Melik C.

164

Managing Manure with Biogas Recovery Systems  

E-print Network

at their 500-cow freestall dairy. The methane-rich biogas generat, which typically contains between 60 to 70 percent methane, 30 to 40 percent carbon dioxide, and trace source of energy with much lower environmental impacts than conventional fossil fuel. The methane

Mukhtar, Saqib

165

Bio-gas production from alligator weeds  

NASA Technical Reports Server (NTRS)

Laboratory experiments were conducted to study the effect of temperature, sample preparation, reducing agents, light intensity and pH of the media, on bio-gas and methane production from the microbial anaerobic decomposition of alligator weeds (Alternanthera philoxeroides. Efforts were also made for the isolation and characterization of the methanogenic bacteria.

Latif, A.

1976-01-01

166

Degradation efficiency of agricultural biogas plants - A full-scale study.  

PubMed

The degradation efficiency of 21 full-scale agricultural CSTR biogas plants was investigated. The residual methane potential of the digestion stages was determined in batch digestion tests (20.0 and 37.0°C). The results of this study showed that the residual methane yield is significantly correlated to the HRT (r=-0.73). An almost complete degradation of the input substrates was achieved due to a HRT of more than 100days (0.097±0.017Nm(3)/kg VS). The feedstock characteristics have the largest impact to the degradation time. It was found that standard values of the methane yield are a helpful tool for evaluating the degradation efficiency. Adapting the HRT to the input materials is the key factor for an efficient degradation in biogas plants. No influence of digester series configuration to the VS degradation was found. The mean VS degradation rate in the total reactor systems was 78±7%. PMID:25453437

Ruile, Stephan; Schmitz, Sabine; Mönch-Tegeder, Matthias; Oechsner, Hans

2014-10-19

167

Comparative performance of fixed-film biological filters: Application of reactor theory  

USGS Publications Warehouse

Nitrification is classified as a two-step consecutive reaction where R1 represents the rate of formation of the intermediate product NO2-N and R2 represents the rate of formation of the final product NO3-N. The relative rates of R1 and R2 are influenced by reactor type characterized hydraulically as plug-flow, plug-flow with dispersion and mixed-flow. We develop substrate conversion models for fixed-film biofilters operating in the first-order kinetic regime based on application of chemical reactor theory. Reactor type, inlet conditions and the biofilm kinetic constants Ki (h-1) are used to predict changes in NH4-N, NO2-N, NO3-N and BOD5. The inhibiting effects of the latter on R1 and R2 were established based on the ?? relation, e.g.:{A formula is presented}where BOD5,max is the concentration that causes nitrification to cease and N is a variable relating Ki to increasing BOD5. Conversion models were incorporated in spreadsheet programs that provided steady-state concentrations of nitrogen and BOD5 at several points in a recirculating aquaculture system operating with input values for fish feed rate, reactor volume, microscreen performance, make-up and recirculating flow rates. When rate constants are standardized, spreadsheet use demonstrates plug-flow reactors provide higher rates of R1 and R2 than mixed-flow reactors thereby reducing volume requirements for target concentrations of NH4-N and NO2-N. The benefit provided by the plug-flow reactor varies with hydraulic residence time t as well as the effective vessel dispersion number, D/??L. Both reactor types are capable of providing net increases in NO2-N during treatment but the rate of decrease in the mixed-flow case falls well behind that predicted for plug-flow operation. We show the potential for a positive net change in NO2-N increases with decreases in the dimensionless ratios K2, (R2 )/K1,( R1 ) and [NO2-N]/[NH4-N] and when the product K1, (R1) t provides low to moderate NH4-N conversions. Maintaining high levels of the latter reduces the effective reactor utilization rate (%) defined here as (RNavg/RNmax)100 where RNavg is the mean reactive nitrogen concentration ([NH4-N] + [NO2-N]) within the reactor, and RNmax represents the feed concentration of the same. Low utilization rates provide a hedge against unexpected increases in substrate loading and reduce water pumping requirements but force use of elevated reactor volumes. Further ?? effects on R1 and R2 can be reduced through use of a tanks-in-series versus a single mixed-flow reactor configuration and by improving the solids removal efficiency of microscreen treatment.

Watten, B.J.; Sibrell, P.L.

2006-01-01

168

Mixed Uranium/Refractory Metal Carbide Fuels for High Performance Nuclear Reactors  

SciTech Connect

Single phase, solid-solution mixed uranium/refractory metal carbides have been proposed as an advanced nuclear fuel for advanced, high-performance reactors. Earlier studies of mixed carbides focused on uranium and either thorium or plutonium as a fuel for fast breeder reactors enabling shorter doubling owing to the greater fissile atom density. However, the mixed uranium/refractory carbides such as (U, Zr, Nb)C have a lower uranium densities but hold significant promise because of their ultra-high melting points (typically greater than 3700 K), improved material compatibility, and high thermal conductivity approaching that of the metal. Various compositions of (U, Zr, Nb)C were processed with 5% and 10% metal mole fraction of uranium. Stoichiometric samples were processed from the constituent carbide powders, while hypo-stoichiometric samples with carbon-to-metal (C/M) ratios of 0.92 were processed from uranium hydride, graphite, and constituent refractory carbide powders. Processing techniques of cold uniaxial pressing, dynamic magnetic compaction, sintering, and hot pressing were investigated to optimize the processing parameters necessary to produce high density (low porosity), single phase, solid-solution mixed carbide nuclear fuels for testing. This investigation was undertaken to evaluate and characterize the performance of these mixed uranium/refractory metal carbides for high performance, ultra-safe nuclear reactor applications. (authors)

Knight, Travis; Anghaie, Samim [Innovative Nuclear Space Power and Propulsion Institute (INSPI), PO Box 116502, University of Florida, Gainesville, FL 32611-6502 (United States)

2002-07-01

169

Anaerobic co-digestion of the organic fraction of municipal solid waste with FOG waste from a sewage treatment plant: Recovering a wasted methane potential and enhancing the biogas yield  

SciTech Connect

Anaerobic digestion is applied widely to treat the source collected organic fraction of municipal solid wastes (SC-OFMSW). Lipid-rich wastes are a valuable substrate for anaerobic digestion due to their high theoretical methane potential. Nevertheless, although fat, oil and grease waste from sewage treatment plants (STP-FOGW) are commonly disposed of in landfill, European legislation is aimed at encouraging more effective forms of treatment. Co-digestion of the above wastes may enhance valorisation of STP-FOGW and lead to a higher biogas yield throughout the anaerobic digestion process. In the present study, STP-FOGW was evaluated as a co-substrate in wet anaerobic digestion of SC-OFMSW under mesophilic conditions (37 {sup o}C). Batch experiments carried out at different co-digestion ratios showed an improvement in methane production related to STP-FOGW addition. A 1:7 (VS/VS) STP-FOGW:SC-OFMSW feed ratio was selected for use in performing further lab-scale studies in a 5 L continuous reactor. Biogas yield increased from 0.38 {+-} 0.02 L g VS{sub feed}{sup -1} to 0.55 {+-} 0.05 L g VS{sub feed}{sup -1} as a result of adding STP-FOGW to reactor feed. Both VS reduction values and biogas methane content were maintained and inhibition produced by long chain fatty acid (LCFA) accumulation was not observed. Recovery of a currently wasted methane potential from STP-FOGW was achieved in a co-digestion process with SC-OFMSW.

Martin-Gonzalez, L., E-mail: lucia.martin@uab.ca [Departament d'Enginyeria Quimica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Colturato, L.F. [Departament d'Enginyeria Quimica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Font, X.; Vicent, T. [Departament d'Enginyeria Quimica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Institut de Ciencia i Tecnologia Ambiental (ICTA) Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)

2010-10-15

170

Pressure-Accelerated Azide-Alkyne Cycloaddition: Micro Capillary versus Autoclave Reactor Performance.  

PubMed

Pressure effects on regioselectivity and yield of cycloaddition reactions have been shown to exist. Nevertheless, high pressure synthetic applications with subsequent benefits in the production of natural products are limited by the general availability of the equipment. In addition, the virtues and limitations of microflow equipment under standard conditions are well established. Herein, we apply novel-process-window (NPWs) principles, such as intensification of intrinsic kinetics of a reaction using high temperature, pressure, and concentration, on azide-alkyne cycloaddition towards synthesis of Rufinamide precursor. We applied three main activation methods (i.e., uncatalyzed batch, uncatalyzed flow, and catalyzed flow) on uncatalyzed and catalyzed azide-alkyne cycloaddition. We compare the performance of two reactors, a specialized autoclave batch reactor for high-pressure operation up to 1800?bar and a capillary flow reactor (up to 400?bar). A differentiated and comprehensive picture is given for the two reactors and the three methods of activation. Reaction speedup and consequent increases in space-time yields is achieved, while the process window for favorable operation to selectively produce Rufinamide precursor in good yields is widened. The best conditions thus determined are applied to several azide-alkyne cycloadditions to widen the scope of the presented methodology. PMID:25522301

Borukhova, Svetlana; Seeger, Andreas D; Noël, Timothy; Wang, Qi; Busch, Markus; Hessel, Volker

2015-02-01

171

High-rate wastewater treatment by aerobic upflow sludge blanket reactor: system performance and characteristics.  

PubMed

A laboratory study was conducted to investigate the characteristics of an aerobic upflow sludge blanket reactor (AUSB) treating synthetic wastewater at a high organic loading. The response of the system was evaluated at different operating conditions, such as pressurization, extent of flow recirculation, and hydraulic retention time. Aeration shear to the biomass in the reactor was totally eliminated by employing oxygenation under pressurization in an external chamber. As a result, the biomass concentration in the reactor could be maintained at 7-10 g VSS l(-1). The AUSB system was able to handle efficiently a volumetric loading of as high as 3.8 kg TOC m(-3) d(-1), which was possibly due to high reactor biomass level and higher bioactivity as indicated by higher sludge specific oxygen uptake rates. However, the treatment capacity of the AUSB was somewhat limited by the substrate and oxygen transport in the sludge bed due to low mixing intensity. The effluent TOC of the AUSB system was relatively higher due to its operation at a high organic loading. The AUSB system performed well under a short term loading shock, and the bacterial activity in the oxygenation chamber was demonstrated to contribute to its improved substrate removal capacity under the shock loading. PMID:15691202

Sharma, K R; Huang, J C

2004-12-01

172

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

PubMed

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. PMID:24837280

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

2014-10-01

173

Benchmarking of the MIT High Temperature Gas-Cooled Reactor TRISO-Coated Particle Fuel Performance Model  

E-print Network

Benchmarking of the MIT High Temperature Gas-Cooled Reactor TRISO-Coated Particle Fuel Performance on Graduate Students #12;#12;Benchmarking of the MIT High Temperature Gas-Cooled Reactor TRISO-Coated Particle in some cases and led to differences in particle failure rate by several orders of magnitude. In addition

174

The Bosch Process-Performance of a Developmental Reactor and Experimental Evaluation of Alternative Catalysts  

NASA Technical Reports Server (NTRS)

Bosch-based reactors have been in development at NASA since the 1960's. Traditional operation involves the reduction of carbon dioxide with hydrogen over a steel wool catalyst to produce water and solid carbon. While the system is capable of completely closing the loop on oxygen and hydrogen for Atmosphere Revitalization, steel wool requires a reaction temperature of 650C or higher for optimum performance. The single pass efficiency of the reaction over steel wool has been shown to be less than 10% resulting in a high recycle stream. Finally, the formation of solid carbon on steel wool ultimately fouls the catalyst necessitating catalyst resupply. These factors result in high mass, volume and power demands for a Bosch system. Interplanetary transportation and surface exploration missions of the moon, Mars, and near-earth objects will require higher levels of loop closure than current technology cannot provide. A Bosch system can provide the level of loop closure necessary for these long-term missions if mass, volume, and power can be kept low. The keys to improving the Bosch system lie in reactor and catalyst development. In 2009, the National Aeronautics and Space Administration refurbished a circa 1980's developmental Bosch reactor and built a sub-scale Bosch Catalyst Test Stand for the purpose of reactor and catalyst development. This paper describes the baseline performance of two commercially available steel wool catalysts as compared to performance reported in the 1960's and 80's. Additionally, the results of sub-scale testing of alternative Bosch catalysts, including nickel- and cobalt-based catalysts, are discussed.

Abney, Morgan B.; Mansell, J. Matthew

2010-01-01

175

Theoretical analysis of the subcritical experiments performed in the IPEN/MB-01 research reactor facility  

SciTech Connect

The theoretical analysis of the subcritical experiments performed at the IPEN/MB-01 reactor employing the coupled NJOY/AMPX-II/TORT systems was successfully accomplished. All the analysis was performed employing ENDF/B-VII.0. The theoretical approach follows all the steps of the subcritical model of Gandini and Salvatores. The theory/experiment comparison reveals that the calculated subcritical reactivity is in a very good agreement to the experimental values. The subcritical index ({xi}) shows some discrepancies although in this particular case some work still have to be made to model in a better way the neutron source present in the experiments. (authors)

Lee, S. M.; Dos Santos, A. [Inst. de Pesquisas Energeticas e Nucleares, Cidade Universitaria, Av. Lineu Prestes, 2242, 05508-000 Sao Paulo - SP (Brazil)

2012-07-01

176

Testing of Passive Safety System Performance for Higher Power Advanced Reactors  

SciTech Connect

This report describes the results of NERI research on the testing of advanced passive safety performance for the Westinghouse AP1000 design. The objectives of this research were: (a) to assess the AP1000 passive safety system core cooling performance under high decay power conditions for a spectrum of breaks located at a variety of locations, (b) to compare advanced thermal hydraulic computer code predictions to the APEX high decay power test data and (c) to develop new passive safety system concepts that could be used for Generation IV higher power reactors.

brian G. Woods; Jose Reyes, Jr.; John Woods; John Groome; Richard Wright

2004-12-31

177

454 pyrosequencing analyses of bacterial and archaeal richness in 21 full-scale biogas digesters.  

PubMed

The microbial community of 21 full-scale biogas reactors was examined using 454 pyrosequencing of 16S rRNA gene sequences. These reactors included seven (six mesophilic and one thermophilic) digesting sewage sludge (SS) and 14 (ten mesophilic and four thermophilic) codigesting (CD) various combinations of wastes from slaughterhouses, restaurants, households, etc. The pyrosequencing generated more than 160,000 sequences representing 11 phyla, 23 classes, and 95 genera of Bacteria and Archaea. The bacterial community was always both more abundant and more diverse than the archaeal community. At the phylum level, the foremost populations in the SS reactors included Actinobacteria, Proteobacteria, Chloroflexi, Spirochetes, and Euryarchaeota, while Firmicutes was the most prevalent in the CD reactors. The main bacterial class in all reactors was Clostridia. Acetoclastic methanogens were detected in the SS, but not in the CD reactors. Their absence suggests that methane formation from acetate takes place mainly via syntrophic acetate oxidation in the CD reactors. A principal component analysis of the communities at genus level revealed three clusters: SS reactors, mesophilic CD reactors (including one thermophilic CD and one SS), and thermophilic CD reactors. Thus, the microbial composition was mainly governed by the substrate differences and the process temperature. PMID:23678985

Sundberg, Carina; Al-Soud, Waleed A; Larsson, Madeleine; Alm, Erik; Yekta, Sepehr S; Svensson, Bo H; Sørensen, Søren J; Karlsson, Anna

2013-09-01

178

Treatment of Slaughter House Wastewater in a Sequencing Batch Reactor: Performance Evaluation and Biodegradation Kinetics  

PubMed Central

Slaughterhouse wastewater contains diluted blood, protein, fat, and suspended solids, as a result the organic and nutrient concentration in this wastewater is vary high and the residues are partially solubilized, leading to a highly contaminating effect in riverbeds and other water bodies if the same is let off untreated. The performance of a laboratory-scale Sequencing Batch Reactor (SBR) has been investigated in aerobic-anoxic sequential mode for simultaneous removal of organic carbon and nitrogen from slaughterhouse wastewater. The reactor was operated under three different variations of aerobic-anoxic sequence, namely, (4+4), (5+3), and (3+5) hr. of total react period with two different sets of influent soluble COD (SCOD) and ammonia nitrogen (NH4+-N) level 1000 ± 50?mg/L, and 90 ± 10?mg/L, 1000 ± 50?mg/L and 180 ± 10?mg/L, respectively. It was observed that from 86 to 95% of SCOD removal is accomplished at the end of 8.0?hr of total react period. In case of (4+4) aerobic-anoxic operating cycle, a reasonable degree of nitrification 90.12 and 74.75% corresponding to initial NH4+-N value of 96.58 and 176.85?mg/L, respectively, were achieved. The biokinetic coefficients (k, Ks, Y, kd) were also determined for performance evaluation of SBR for scaling full-scale reactor in future operation. PMID:24027751

Kundu, Pradyut; Debsarkar, Anupam; Mukherjee, Somnath

2013-01-01

179

Experimental Evaluation of the Thermal Performance of a Water Shield for a Surface Power Reactor  

SciTech Connect

Water based reactor shielding is being investigated for use on initial lunar surface power systems. A water shield may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. Natural convection in a 100 kWt lunar surface reactor shield design is evaluated with 2 kW power input to the water in the Water Shield Testbed (WST) at the NASA Marshall Space Flight Center. The experimental data from the WST is used to validate a CFD model. Performance of the water shield on the lunar surface is then predicted with a CFD model anchored to test data. The experiment had a maximum water temperature of 75 deg. C. The CFD model with 1/6-g predicts a maximum water temperature of 88 deg. C with the same heat load and external boundary conditions. This difference in maximum temperature does not greatly affect the structural design of the shield, and demonstrates that it may be possible to use water for a lunar reactor shield.

Pearson, J. Boise; Stewart, Eric T. [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Reid, Robert S. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States)

2007-01-30

180

EXPERIMENTAL EVALUATION OF THE THERMAL PERFORMANCE OF A WATER SHIELD FOR A SURFACE POWER REACTOR  

SciTech Connect

Water based reactor shielding is being investigated for use on initial lunar surface power systems. A water shield may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. Natural convection in a 100 kWt lunar surface reactor shield design is evaluated with 2 kW power input to the water in the Water Shield Testbed (WST) at the NASA Marshall Space Flight Center. The experimental data from the WST is used to validate a CFD model. Performance of the water shield on the lunar surface is then predicted with a CFD model anchored to test data. The experiment had a maximum water temperature of 75 C. The CFD model with 1/6-g predicts a maximum water temperature of 88 C with the same heat load and external boundary conditions. This difference in maximum temperature does not greatly affect the structural design of the shield, and demonstrates that it may be possible to use water for a lunar reactor shield.

REID, ROBERT S. [Los Alamos National Laboratory; PEARSON, J. BOSIE [Los Alamos National Laboratory; STEWART, ERIC T. [Los Alamos National Laboratory

2007-01-16

181

Performance and emissions of a catalytic reactor with propane, diesel, and Jet A fuels  

NASA Technical Reports Server (NTRS)

Tests were made to determine the performance and emissions of a catalytic reactor operated with propane, No. 2 diesel, and Jet A fuels. A 12-cm diameter and 16-cm long catalytic reactor using a proprietary noble metal catalyst was operated at an inlet temperature of 800 K, a pressure of 300,000 Pa and reference velocities of 10 to 15 m/s. No significant differences between the performance of the three fuels were observed when 98.5 percent purity propane was used. The combustion efficiency for 99.8-percent purity propane tested later was significantly lower, however. The diesel fuel contained 135 ppm of bound nitrogen and consequently produced the highest NOx emissions of the three fuels. As much as 85 percent of the bound nitrogen was converted to NOx. Steady-state emissions goals based on half the most stringent proposed automotive standards were met when the reactor was operated at an adiabatic combustion temperature higher than 1350 K with all fuels except the 99.8-percent purity propane. With that fuel, a minimum temperature of 1480 K was required.

Anderson, D. N.

1977-01-01

182

Benchmarking of Software and Methods for Use in Transient Multidimensional Fuel Performance with Spatial Reactor Kinetics  

SciTech Connect

The key physics involved in accurate prediction of reactor-fuel-element behavior includes neutron transport and thermal hydraulics. The thermal hydraulic feedback mechanism is primarily provided through cross sections to the neutron transport that are temperature and density dependent. Historically, this coupling was primarily seen only in reactor simulators, which are well suited to model the reactor core, giving only a coarse treatment to individual fuel pins as well as simple models for thermal distribution calculations. This poor resolution on the primary coupling mechanisms can lead to conservatisms that should be removed to improve fuel design and performance. This work seeks to address the resolution of space-time-dependent neutron kinetics with thermal feedback within the fuel pin scale in the multiphysics framework. The specific application of this new capability is transient performance analysis of space-time-dependent temperature distribution of fuel elements. The coupling between the neutron transport and the thermal feedback is extremely important in this highly coupled problem, primarily applicable to reactivity-initiated-accidents (RIAs) and loss-of-coolant-accidents (LOCAs). The capability developed will include the coupling of the time-dependent neutron transport with the time-dependent thermal diffusion capability. An improvement in resolution and coupling is proposed by developing neutron transport models that are internally coupled with high fidelity within fuel pin thermal calculations in a multiphysics framework. Good agreement is shown with benchmarks and problems from the literature of RIAs and LOCAs for the tools used.

Banfield, James E [ORNL] [ORNL; Clarno, Kevin T [ORNL] [ORNL; Hamilton, Steven P [ORNL] [ORNL; Maldonado, G Ivan [ORNL] [ORNL; Philip, Bobby [ORNL] [ORNL; Baird, Mark L [ORNL] [ORNL

2012-01-01

183

Benchmarking of software and methods for use in transient multidimensional fuel performance with spatial reactor kinetics  

SciTech Connect

The key physics involved in accurate prediction of reactor-fuel-element behavior includes neutron transport and thermal hydraulics. The thermal hydraulic feedback mechanism is primarily provided through cross sections to the neutron transport that are temperature and density dependent. Historically, this coupling was primarily seen only in reactor simulators, which are well suited to model the reactor core, giving only a coarse treatment to individual fuel pins as well as simple models for thermal distribution calculations. This poor resolution on the primary coupling mechanisms can lead to conservatisms that should be removed to improve fuel design and performance. This work seeks to address the resolution of space-time-dependent neutron kinetics with thermal feedback within the fuel pin scale in the multi-physics framework. The specific application of this new capability is transient performance analysis of space-time-dependent temperature distribution of fuel elements. The coupling between the neutron transport and the thermal feedback is extremely important in this highly coupled problem, primarily applicable to reactivity-initiated- accidents (RIAs) and loss-of-coolant-accidents (LOCAs). The capability developed will include the coupling of the time-dependent neutron transport with the time-dependent thermal diffusion capability. An improvement in resolution and coupling is proposed by developing neutron transport models that are internally coupled with high fidelity within fuel pin thermal calculations in a multi-physics framework. Good agreement is shown with benchmarks and problems from the literature of RIAs and LOCAs for the tools used. (authors)

Banfield, J. E. [Dept. of Nuclear Engineering, Univ. of Tennessee, Knoxville, TN 37996-2300 (United States); Clarno, K. T.; Hamilton, S. P. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Maldonado, G. I. [Dept. of Nuclear Engineering, Univ. of Tennessee, Knoxville, TN 37996-2300 (United States); Philip, B.; Baird, M. L. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2012-07-01

184

Commercial-Scale Performance Predictions for High-Temperature Electrolysis Plants Coupled to Three Advanced Reactor Types  

SciTech Connect

This report presents results of system analyses that have been developed to assess the hydrogen production performance of commercial-scale high-temperature electrolysis (HTE) plants driven by three different advanced reactor – power-cycle combinations: a high-temperature helium cooled reactor coupled to a direct Brayton power cycle, a supercritical CO2-cooled reactor coupled to a direct recompression cycle, and a sodium-cooled fast reactor coupled to a Rankine cycle. The system analyses were performed using UniSim software. The work described in this report represents a refinement of previous analyses in that the process flow diagrams include realistic representations of the three advanced reactors directly coupled to the power cycles and integrated with the high-temperature electrolysis process loops. In addition, this report includes parametric studies in which the performance of each HTE concept is determined over a wide range of operating conditions. Results of the study indicate that overall thermal-to- hydrogen production efficiencies (based on the low heating value of the produced hydrogen) in the 45 - 50% range can be achieved at reasonable production rates with the high-temperature helium cooled reactor concept, 42 - 44% with the supercritical CO2-cooled reactor and about 33 - 34% with the sodium-cooled reactor.

M. G. McKellar; J. E. O'Brien; J. S. Herring

2007-09-01

185

Analysis of factors affecting the performance of partial nitrification in a sequencing batch reactor.  

PubMed

The objective of this study was to analyze the factors affecting the performance of partial nitrification in a sequencing batch reactor. During a 140-day long-term operation, influent pH value, dissolved oxygen (DO), and chemical oxygen demand/nitrogen (COD/N) ratio were selected as operating factors to evaluate the maintenance and recovery of nitrite accumulation. Results showed that high DO concentration (2-4 mg/L) could damage nitrite accumulation immediately. However, nitrite accumulation ratio (NAR) could be increased from 1.68 ± 1.51 to 35.46 ± 7.86% when increasing the pH values from 7.5 to 8.3 due to the increased free ammonia concentration. Afterwards, stable partial nitrification and high NAR could be recovered when the reactor operated under low DO concentration (0.5-1.0 mg/L). However, it required a long time to recover the partial nitrification of the reactor when the influent COD/N ratios were altered. Fluorescence in situ hybridization analysis implied that ammonium oxidizing bacteria were completely recovered to the dominant nitrifying bacteria in the system. Meanwhile, sludge volumetric index of the reactor gradually decreased from 115.6 to 56.6 mL/g, while the mean diameter of sludge improved from 74.57 to 428.8 ?m by using the strategy of reducing settling time. The obtained results could provide useful information between the operational conditions and the performance of partial nitrification when treating nitrogen-rich industrial wastewater. PMID:23942879

Wei, Dong; Du, Bin; Xue, Xiaodong; Dai, Peng; Zhang, Jian

2014-02-01

186

Thermic model to predict biogas production in unheated fixed-dome digesters buried in the ground.  

PubMed

In many developing countries, simple biogas digesters are used to produce energy for domestic purposes from anaerobic digestion of animal manure. We developed a simple, one-dimensional (1-D), thermal model with easily available input data for unheated, unstirred, uninsulated, fixed-dome digesters buried in the soil to study heat transfer between biogas digester and its surroundings. The predicted temperatures in the dome, biogas, and slurry inside the digester and the resulting biogas production are presented and validated. The model was well able to estimate digester temperature (linear slope nearly 1, R(2) = 0.96). Model validation for methane production gave root-mean-square error (RMSE) of 54.4 L CH4 digester(-1) day(-1) and relative-root-mean-square errors (rRMSEP(%)) of 35.4%. The validation result was considerably improved if only using winter data (RMSE = 26.1 L CH4 digester(-1) day(-1); rRMSEP(%) = 17.7%). The model performed satisfactorily in light of the uncertainties attached to it. Since unheated digesters suffer critically low methane production during the winter, the model could be particularly useful for assessing methane production and for improving the ability of unheated digesters to provide sufficient energy during cold periods. PMID:24517412

Terradas-Ill, Georgina; Pham, Cuong H; Triolo, Jin M; Martí-Herrero, Jaime; Sommer, Sven G

2014-03-18

187

Biogas Potential in the United States (Fact Sheet)  

SciTech Connect

Biogas has received increased attention as an alternative energy source in the United States. The factsheet provides information about the biogas (methane) potential from various sources in the country (by county and state) and estimates the power generation and transportation fuels production (renewable natural gas) potential from these biogas sources. It provides valuable information to the industry, academia and policy makers in support of their future decisions.

Not Available

2013-10-01

188

Performance evaluation of anaerobic hybrid reactors with different packing media for treating wastewater of mild alkali treated rice straw in ethanol fermentation process.  

PubMed

Four anaerobic hybrid reactors with different packing media viz. gravel (R1), pumice stone (R2), polypropylene saddles (R3) and ceramic saddles (R4) were operated in semi-continuous mode. Biomethanation potential of the wastewater generated during alkali-treatment of rice straw in ethanol production process was investigated at ambient conditions. The reactors were operated with varying organic loading rates (0.861-4.313 g COD l(-1) d(-1)) and hydraulic retention time (3-15 days). Higher COD removal efficiency (69.2%) and methane yield (0.153 l CH4 g(-1) CODadded) were achieved in reactor R2 at 15 days HRT. Modified Stover-Kincannon model was applied to estimate the bio-kinetic coefficients and fitness of the model was checked by the regression coefficient for all the reactors. The model showed an excellent correlation between the experimental and predicted values. The present study demonstrated the treatment of wastewater from alkali treated rice straw for production of biogas. PMID:24291309

Narra, Madhuri; Balasubramanian, Velmurugan; Mehta, Himali; Dixit, Garima; Madamwar, Datta; Shah, Amita R

2014-01-01

189

Analytical methodology for sampling and analysing eight siloxanes and trimethylsilanol in biogas from different wastewater treatment plants in Europe.  

PubMed

Siloxanes and trimethylsilanol belong to a family of organic silicone compounds that are currently used extensively in industry. Those that are prone to volatilisation become minor compounds in biogas adversely affecting energetic applications. However, non-standard analytical methodologies are available to analyse biogas-based gaseous matrixes. To this end, different sampling techniques (adsorbent tubes, impingers and tedlar bags) were compared using two different configurations: sampling directly from the biogas source or from a 200 L tedlar bag filled with biogas and homogenised. No significant differences were apparent between the two sampling configurations. The adsorbent tubes performed better than the tedlar bags and impingers, particularly for quantifying low concentrations. A method for the speciation of silicon compounds in biogas was developed using gas chromatography coupled with mass spectrometry working in dual scan/single ion monitoring mode. The optimised conditions could separate and quantify eight siloxane compounds (L2, L3, L4, L5, D3, D4, D5 and D6) and trimethylsilanol within fourteen minutes. Biogas from five waste water treatment plants located in Spain, France and England was sampled and analysed using the developed methodology. The siloxane concentrations in the biogas samples were influenced by the anaerobic digestion temperature, as well as the nature and composition of the sewage inlet. Siloxanes D4 and D5 were the most abundant, ranging in concentration from 1.5 to 10.1 and 10.8 to 124.0 mg Nm(-3), respectively, and exceeding the tolerance limit of most energy conversion systems. PMID:24491768

Raich-Montiu, J; Ribas-Font, C; de Arespacochaga, N; Roig-Torres, E; Broto-Puig, F; Crest, M; Bouchy, L; Cortina, J L

2014-02-17

190

Performance Assessment of a Fusion Hybrid Reactor Based on the Gasdynamic Mirror  

NASA Astrophysics Data System (ADS)

A preliminary evaluation of the performance of a fusion hybrid reactor whose fusion component is the gasdynamic mirror (GDM) is presented. Since the primary role of the fusion component is to supply high energy neutrons that will induce fission reactions in a blanket surrounding the plasma, it can operate at or below ``break even'' condition. Unlike other fusion devices proposed for this component, the GDM is a linear, cylindrically symmetric device that can operate in steady state making it uniquely suited for this application. We investigate the power producing capability of such a hybrid reactor using the thorium fuel cycle whereby neutrons generated by DT reactions in the GDM impinge on a thorium-232 blanket. These 14.1 MeV neutrons will breed uranium-233 in the blanket and simultaneously burn it to generate power. We treat both the fusion component and the blanket as semi-infinite cylinders so that one-dimensional analysis can be applied. The two relevant equations in this regard are the time evolution of the U-233 density in the blanket, and the neutron one dimensional diffusion equation. We address the steady state operation of this reactor and find that it can produce gigawatts of power per cm, safely since it is ``subcritical,'' and securely since the fuel cycle is proliferation resistant. The approach to steady state will also be presented and analyzed.

Kammash, Terry

2010-11-01

191

Pretreaments of Chinese Agricultural residues to increase biogas production.  

E-print Network

?? Development of biological conversion of lignocellulosic biomass to biogas is one approach to utilize straw comprehensively. However, high lignin contents of lignocellulosic materials results… (more)

Wang, Yu

2010-01-01

192

A technoeconomic assessment of solar-assisted biogas systems  

SciTech Connect

Biogas has been recognized as one of the best available renewable and decentralized sources of energy and organic fertilizer for a country like India. There is enough evidence to prove that temperature has a profound influence on the rate of biogas production. In temperate climates, where the winters are mild, solar energy systems can be effectively used to increase the temperature of the biogas digester to the desired level. This paper examines various techniques, such as a solar greenhouse on the biogas digester, a shallow solar pond water heater, insulation, and a heat exchanger, and their technoeconomic viability.

Bansal, N.K. (Centre of Energy Studies Indian Institute of Technology, Delhi Hauz Khas, New Delhi-110016 (IN))

1988-01-01

193

Techno-socio-economic study of bio-gas plants  

SciTech Connect

This study covers technological, social and economic aspects of the biogas program in Chitawan, Nepal. Many interesting facts are revealed which may be useful for future planning of Nepalese biogas programs. Concerning the social aspects, only big farmers (having more than 4 bighas of land and more than 10 domestic animals) were found to have biogas plants. No farmer who had a biogas plant was illiterate. As for the technical aspects of the total gas ovens used in the area, 66% were of BTI design. Most of the ovens were of 0.45-m/sup 3/ capacity. The life of BTI ovens was found to be shorter than the life of ovens of other companies. BTI ovens are not useful when farmers have to use a big pot for cooking. All farmers of the area were found to be convinced of the utility of the biogas plant. With regard to the economic aspects of using biogas plants, farmers were able to save 53% of the total expenditure which they had been spending for fuel. Wood consumption was reduced to 50% by using biogas. The internal rate of return of a 2.8-m/sup 3/ biogas plant was found to be 14% assuming that the plant would last for 20 years. Most of the farmers in the area did not have biogas plants. The main reason given was that there were not enough capital and cattle to begin such an operation.

Not Available

1981-01-01

194

On the factors influencing the performance of solar reactors for water disinfection with photosensitized singlet oxygen.  

PubMed

Two solar reactors based on compound parabolic collectors (CPCs) were optimized for water disinfection by photosensitized singlet oxygen (1O2) production in the heterogeneous phase. Sensitizing materials containing Ru(II) complexes immobilized on porous silicone were produced, photochemically characterized, and successfully tested for the inactivation of up to 10(4) CFU mL(-1) of waterborne Escherichia coli (gram-negative) or Enterococcus faecalis (gram-positive) bacteria. The main factors determining the performance of the solar reactors are the type of photosensitizing material, the sensitizer loading, the CPC collector geometry (fin- vs coaxial-type), the fluid rheology, and the balance between concurrent photothermal--photolytic and 1O2 effects on the microorganisms' inactivation. In this way, at the 40 degrees N latitude of Spain, water can be disinfected on a sunny day (0.6-0.8 MJ m(-2) L(-1) accumulated solar radiation dose in the 360-700 nm range, typically 5-6 h of sunlight) with a fin-type reactor containing 0.6 m2 of photosensitizing material saturated with tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (ca. 2.0 g m(-2)). The optimum rheological conditions require laminar-to-transitional water flow in both prototypes. The fin-type system showed better inactivation efficiency than the coaxial reactor due to a more important photolytic contribution. The durability of the sensitizing materials was tested and the operational lifetime of the photocatalyst is at least three months without any reduction in the bacteria inactivation efficiency. Solar water disinfection with 1O2-generating films is demonstrated to be an effective technique for use in isolated regions of developing countries with high yearly average sunshine. PMID:18350912

Manjón, Francisco; Villén, Laura; García-Fresnadillo, David; Orellana, Guillermo

2008-01-01

195

Hydrogen production from biogas using hot slag  

Microsoft Academic Search

Possibility of hydrogen production from biogas using hot slag has been studied, in which decomposition rate of CO2–CH4 in a packed bed of granulated slag was measured at constant flow-rate and pressure. The molten slag, discharged at high temperature over 1700K from smelting industries such as steelmaking or municipal waste incineration. It has enough potential for replacing energy required for

Hadi Purwanto; Tomohiro Akiyama

2006-01-01

196

Biogas as a source of rural energy  

SciTech Connect

The hilly state of Himachal Pradesh, with nearly 2.15 million cattle and 0.7 million buffalo, has the potential to install 0.64 million biogas plants of 1 m{sup 3} size. These plants could generate nearly 4.90 x 105 m{sup 3} of biogas, equivalent to 3.07 x 10{sup 5} L kerosene per day to meet domestic energy needs of nearly one-fourth of its rural population. During 1982--1998, only 12.8% of this potential was achieved. The percent of possible potential achieved in plant installations in 12 districts of this state, namely, Bilaspur, Chamba, Hamirpur, Kangra, Kinnaur, Kullu, Lahul-Spiti, Mandi, Shimla, Sirmour, Solan, and Una, are 35.35, 1.70, 20.96, 8.67, 1.54, 6.96, 0.00, 18.49, 3.84, 8.521, 18.29, and 13.23%, respectively. There is a need to strengthen biogas promotion, particularly in the districts of Kangra, Mandi, Solan, and Una, which range from mid-hill to low-hill terrain and which have large potential due to high concentration of bovine population. Increased costs and comparatively low rate of subsidies has resulted in a decreasing rate of plant installation annually, from 3,500 during 1987--1992 to fewer than 1,200 during 1995--1998. The percentage of functioning plants was 82% in 1987--1988 but has decreased to 63%. To ensure proper installation and functionality of plants, the authors discuss the needed improvements in the biogas promotion program.

Kalia, A.K.

2000-01-01

197

Biogas production: current state and perspectives  

Microsoft Academic Search

Anaerobic digestion of energy crops, residues, and wastes is of increasing interest in order to reduce the greenhouse gas\\u000a emissions and to facilitate a sustainable development of energy supply. Production of biogas provides a versatile carrier\\u000a of renewable energy, as methane can be used for replacement of fossil fuels in both heat and power generation and as a vehicle\\u000a fuel.

Peter Weiland

2010-01-01

198

Aqueous processing of U-10Mo scrap for high performance research reactor fuel  

NASA Astrophysics Data System (ADS)

The Global Threat Reduction Initiative (GTRI) Conversion program, which is part of the US government's National Nuclear Security Administration (NNSA), supports the conversion of civilian use of highly enriched uranium (HEU) to low enriched uranium (LEU) for reactor fuel and targets. The reason for conversion is to eliminate the use of any material that may pose a threat to the United States or other foreign countries. High performance research reactors (HPRRs) cannot make the conversion to a standard LEU fuel because they require a more dense fuel to meet their performance requirements. As a result, a more dense fuel consisting of a monolithic uranium-molybdenum alloy containing 10% (w/w) Mo with Al cladding and a Zr bonding-layer is being considered. Significant losses are expected in the fabrication of this fuel, so a means to recycle the scrap pieces is needed. Argonne National Laboratory has developed an aqueous-processing flowsheet for scrap recovery in the fuel fabrication process for high-density LEU-monolithic fuel based on data found in the literature. Experiments have been performed to investigate dissolution conditions for solutions containing approximately 20 g-U/L and 50 g-U/L with and without Fe(NO3)3. HNO3 and HF concentrations have been optimized for timely dissolution of the fuel scrap and prevention of the formation of the U-Zr2 intermetallic, explosive complex, while meeting the requirements needed for further processing.

Youker, Amanda J.; Stepinski, Dominique C.; Maggos, Laura E.; Bakel, Allen J.; Vandegrift, George F.

2012-08-01

199

Effect of auxotrophies on yeast performance in aerated fed-batch reactor  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer The paper contributes to fill the gap existing between the basic and applied research. Black-Right-Pointing-Pointer Mathematical model sheds light on the physiology of auxotrophic yeast strains. Black-Right-Pointing-Pointer Yeast behavior in fed-batch is influenced by biological and environmental determinants. Black-Right-Pointing-Pointer Process optimization would make possible the production of heterologous proteins which are not yet on the market. -- Abstract: A systematic investigation on the effects of auxotrophies on the performance of yeast in aerated fed-batch reactor was carried out. Six isogenic strains from the CEN.PK family of Saccharomyces cerevisiae, one prototroph and five auxotrophs, were grown in aerated fed-batch reactor using the same operative conditions and a proper nutritional supplementation. The performance of the strains, in terms of final biomass decreased with increasing the number of auxotrophies. Auxotrophy for leucine exerted a profound negative effect on the performance of the strains. Accumulation of reactive oxygen species (ROS) in the cells of the strain carrying four auxotrophies and its significant viability loss, were indicative of an oxidative stress response induced by exposure of cells to the environmental conditions. The mathematical model was fundamental to highlight how the carbon flux, depending on the number and type of auxotrophies, was diverted towards the production of increasingly large quantities of energy for maintenance.

Landi, Carmine; Paciello, Lucia [Dept. Ingegneria Industriale, Universita di Salerno, Via Ponte Don Melillo, 84084 Fisciano, Salerno (Italy)] [Dept. Ingegneria Industriale, Universita di Salerno, Via Ponte Don Melillo, 84084 Fisciano, Salerno (Italy); Alteriis, Elisabetta de [Dept. Biologia Strutturale e Funzionale, Universita degli Studi di Napoli 'Federico II', Via Cinthia, 80100 Napoli (Italy)] [Dept. Biologia Strutturale e Funzionale, Universita degli Studi di Napoli 'Federico II', Via Cinthia, 80100 Napoli (Italy); Brambilla, Luca [Dept. Biotecnologie e Bioscienze, Universita Milano-Bicocca, Piazza della Scienza, 20126 Milano (Italy)] [Dept. Biotecnologie e Bioscienze, Universita Milano-Bicocca, Piazza della Scienza, 20126 Milano (Italy); Parascandola, Palma, E-mail: pparascandola@unisa.it [Dept. Ingegneria Industriale, Universita di Salerno, Via Ponte Don Melillo, 84084 Fisciano, Salerno (Italy)] [Dept. Ingegneria Industriale, Universita di Salerno, Via Ponte Don Melillo, 84084 Fisciano, Salerno (Italy)

2011-10-28

200

Climate balance of biogas upgrading systems  

SciTech Connect

One of the numerous applications of renewable energy is represented by the use of upgraded biogas where needed by feeding into the gas grid. The aim of the present study was to identify an upgrading scenario featuring minimum overall GHG emissions. The study was based on a life-cycle approach taking into account also GHG emissions resulting from plant cultivation to the process of energy conversion. For anaerobic digestion two substrates have been taken into account: (1) agricultural resources and (2) municipal organic waste. The study provides results for four different upgrading technologies including the BABIU (Bottom Ash for Biogas Upgrading) method. As the transport of bottom ash is a critical factor implicated in the BABIU-method, different transport distances and means of conveyance (lorry, train) have been considered. Furthermore, aspects including biogas compression and energy conversion in a combined heat and power plant were assessed. GHG emissions from a conventional energy supply system (natural gas) have been estimated as reference scenario. The main findings obtained underlined how the overall reduction of GHG emissions may be rather limited, for example for an agricultural context in which PSA-scenarios emit only 10% less greenhouse gases than the reference scenario. The BABIU-method constitutes an efficient upgrading method capable of attaining a high reduction of GHG emission by sequestration of CO{sub 2}.

Pertl, A., E-mail: andreas.pertl@boku.ac.a [Institute of Waste Management, Department of Water, Atmosphere and Environment, University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 107, A-1190 Wien (Austria); Mostbauer, P.; Obersteiner, G. [Institute of Waste Management, Department of Water, Atmosphere and Environment, University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 107, A-1190 Wien (Austria)

2010-01-15

201

Biogas and energy production from cattle waste  

SciTech Connect

Biomass is one of the longest used energy sources employed in human activity. The bioconversion of organic matter to biogas is a complex anaerobic fermentation process involving the action of microorganisms such as methane producing bacteria. In this paper, biogas and energy production from cattle waste is investigated. There are two significant reasons that motivate this study. First, treating animal waste with the technology of anaerobic digestion can reduce environmental pollution and generate a relatively cheap and easily available source of energy in dairy farms. The gas produced can be used for space and water heating of farm houses, cooking, lighting, grain drying and as a fuel for heating greenhouses during cold weather. It also has the potential to run other small industries. Second, it is an effective way of managing cattle waste as well as producing a quick acting, non-toxic fertilizer for agricultural use. A working model of biogas plant is studied in this paper and its economic value as an alternative energy source is examined. An alternative to direct generation of electricity, is to convert the methane from the biomass to methanol. Methanol is an excellent fuel for internal combustion engines and can easily compete with gasoline in many nations where gasoline costs over $4 per US gallon.

Chakravarthi, J. [Hood Coll., Frederick, MD (United States). Dept. of Environmental Biology

1997-12-31

202

Advanced Fuels Campaign Light Water Reactor Accident Tolerant Fuel Performance Metrics  

SciTech Connect

The safe, reliable and economic operation of the nation’s nuclear power reactor fleet has always been a top priority for the United States’ nuclear industry. As a result, continual improvement of technology, including advanced materials and nuclear fuels, remains central to industry’s success. Decades of research combined with continual operation have produced steady advancements in technology and yielded an extensive base of data, experience, and knowledge on light water reactor (LWR) fuel performance under both normal and accident conditions. In 2011, following the Great East Japan Earthquake, resulting tsunami, and subsequent damage to the Fukushima Daiichi nuclear power plant complex, enhancing the accident tolerance of LWRs became a topic of serious discussion. As a result of direction from the U.S. Congress, the U.S. Department of Energy Office of Nuclear Energy (DOE-NE) initiated an Accident Tolerant Fuel (ATF) Development program. The complex multiphysics behavior of LWR nuclear fuel makes defining specific material or design improvements difficult; as such, establishing qualitative attributes is critical to guide the design and development of fuels and cladding with enhanced accident tolerance. This report summarizes a common set of technical evaluation metrics to aid in the optimization and down selection of candidate designs. As used herein, “metrics” describe a set of technical bases by which multiple concepts can be fairly evaluated against a common baseline and against one another. Furthermore, this report describes a proposed technical evaluation methodology that can be applied to assess the ability of each concept to meet performance and safety goals relative to the current UO2 – zirconium alloy system and relative to one another. The resultant ranked evaluation can then inform concept down-selection, such that the most promising accident tolerant fuel design option(s) can continue to be developed for lead test rod or lead test assembly insertion into a commercial reactor within the desired timeframe (by 2022).

Brad Merrill; Melissa Teague; Robert Youngblood; Larry Ott; Kevin Robb; Michael Todosow; Chris Stanek; Mitchell Farmer; Michael Billone; Robert Montgomery; Nicholas Brown; Shannon Bragg-Sitton

2014-02-01

203

Performance Analyses of 38 kWe Turbo-Machine Unit for Space Reactor Power Systems  

SciTech Connect

This paper developed a design and investigated the performance of 38 kWe turbo-machine unit for space nuclear reactor power systems with Closed Brayton Cycle (CBC) energy conversion. The compressor and turbine of this unit are scaled versions of the NASA's BRU developed in the sixties and seventies. The performance results of turbo-machine unit are calculated for rotational speed up to 45 krpm, variable reactor thermal power and system pressure, and fixed turbine and compressor inlet temperatures of 1144 K and 400 K. The analyses used a detailed turbo-machine model developed at University of New Mexico that accounts for the various energy losses in the compressor and turbine and the effect of compressibility of the He-Xe (40 mole/g) working fluid with increased flow rate. The model also accounts for the changes in the physical and transport properties of the working fluid with temperature and pressure. Results show that a unit efficiency of 24.5% is achievable at rotation speed of 45 krpm and system pressure of 0.75 MPa, assuming shaft and electrical generator efficiencies of 86.7% and 90%. The corresponding net electric power output of the unit is 38.5 kWe, the flow rate of the working fluid is 1.667 kg/s, the pressure ratio and polytropic efficiency for the compressor are 1.60 and 83.1%, and 1.51 and 88.3% for the turbine.

Gallo, Bruno M.; El-Genk, Mohamed S. [Institute for Space and Nuclear Power Studies and Chemical and Nuclear Engineering Department, University of New Mexico, Albuquerque, NM, 87131 (United States)

2008-01-21

204

Computational Neutronics Methods and Transmutation Performance Analyses for Light Water Reactors  

SciTech Connect

The urgency for addressing repository impacts has grown in the past few years as a result of Spent Nuclear Fuel (SNF) accumulation from commercial nuclear power plants. One obvious path that has been explored by many is to eliminate the transuranic (TRU) inventory from the SNF thus reducing the need for additional long term repository storage sites. One strategy for achieving this is to burn the separated TRU elements in the currently operating U.S. Light Water Reactor (LWR) fleet. Many studies have explored the viability of this strategy by loading a percentage of LWR cores with TRU in the form of either Mixed Oxide (MOX) fuels or Inert Matrix Fuels (IMF). A task was undertaken at INL to establish specific technical capabilities to perform neutronics analyses in order to further assess several key issues related to the viability of thermal recycling. The initial computational study reported here is focused on direct thermal recycling of IMF fuels in a heterogeneous Pressurized Water Reactor (PWR) bundle design containing Plutonium, Neptunium, Americium, and Curium (IMF-PuNpAmCm) in a multi-pass strategy using legacy 5 year cooled LWR SNF. In addition to this initial high-priority analysis, three other alternate analyses with different TRU vectors in IMF pins were performed. These analyses provide comparison of direct thermal recycling of PuNpAmCm, PuNpAm, PuNp, and Pu.

M. Asgari; B. Forget; S. Piet; R. Ferrer; S. Bays

2007-03-01

205

Retrofitting hetrotrophically cultivated algae biomass as pyrolytic feedstock for biogas, bio-char and bio-oil production encompassing biorefinery.  

PubMed

Algal biomass grown hetrotrophically in domestic wastewater was evaluated as pyrolytic feedstock for harnessing biogas, bio-oil and bio-char. Freshly harvested microalgae (MA) and lipid extracted microalgae (LEMA) were pyrolysed in packed bed reactor in the presence and absence of sand as additive. MA (without sand additive) depicted higher biogas (420ml/g; 800°C; 3h) and bio-oil (0.70ml/g; 500°C; 3h). Sand addition enhanced biogas production (210ml/g; 600°C; 2h) in LEMA operation. The composition of bio-gas and bio-oil was found to depend on the nature of feedstock as well as the process conditions viz., pyrolytic-temperature, retention time and presence of additive. Sand additive improved the H2 composition while pyrolytic temperature increment caused a decline in CO2 fraction. Bio-char productivity increased with increasing temperature specifically with LEMA. Integration of thermo-chemical process with microalgae cultivation showed to yield multiple resources and accounts for environmental sustainability in the bio-refinery framework. PMID:25446787

Sarkar, Omprakash; Agarwal, Manu; Naresh Kumar, A; Venkata Mohan, S

2015-02-01

206

Pilot project of biogas production from pig manure and urine mixture at ambient temperature in Ventanilla (Lima, Peru)  

SciTech Connect

Parque Porcino de Ventanilla has an extension of 840 ha with 2200 farmers dedicated to pig production. There is a lack of services in the area (i.e., water supply, electricity, or waste collection). Anaerobic treatment of pig manure would replace current dumping and incineration, reducing environmental pollution and hazards to public health, as well as providing an organic fertilizer and biogas. The objective of the present work was to study the viability of ambient temperature anaerobic digestion of pig manure diluted in urine, by means of on-site pilot scale reactors. The final goal was to establish design parameters for anaerobic digesters to be implemented; since it was part of a project to improve life conditions for the farmers through the incorporation of better management techniques. Experiments were carried out in a low-cost pilot plant, which consists of three anaerobic digesters (225 L total volume), without heating or agitation, placed in a greenhouse. The start-up of the digestion process was performed with a mixture of temperature adapted pig manure-sludge and fresh rumen, and showed a good performance regardless of the dilution of pig manure with water or urine, which is a key parameter due to the scarcity of water in the area under study.

Ferrer, I. [Environmental Engineering Division, Department of Hydraulic Maritime and Environmental Engineering, Technical University of Catalonia (UPC), C/Jordi Girona 1-3, Modul D1, 08034 Barcelona (Spain); GIRO Technological Center, Rambla Pompeu Fabra 1, 08100 Mollet del Valles, Barcelona (Spain)], E-mail: ivet.ferrer@upc.edu; Gamiz, M. [Environmental Engineering Division, Department of Hydraulic Maritime and Environmental Engineering, Technical University of Catalonia (UPC), C/Jordi Girona 1-3, Modul D1, 08034 Barcelona (Spain); Almeida, M.; Ruiz, A. [Ciudad Saludable NLO, Av. Jorge Basadre 255, Of. 401, Lima 27 (Peru)

2009-01-15

207

Performance of Magnet Insulation Systems at Low Temperature and After Reactor Irradiation  

SciTech Connect

Advanced composite materials reinforced with boron-free glass fibers are candidate insulation materials for fusion magnets, in particular for ITER. Thus, these systems require an excellent performance and mechanical integrity after irradiation. The present innovative organic insulation system consists of R-glass fiber reinforced tapes impregnated with an advanced cyanate-ester/epoxy resin. This composite is suitable for vacuum-pressure impregnation. In order to assess the radiation resistance of the mechanical properties, the laminate was irradiated in the TRIGA reactor (Vienna) to the ITER design fluence level of 1x1022 m-2 (E>0.1 MeV). The blend was screened at 77 K using the static tensile and short-beam-shear test prior to and after irradiation. In addition, tension-tension fatigue measurements were done in order to investigate the material performance under pulsed operating conditions.

Bittner-Rohrhofer, K.; Humer, K.; Fillunger, H.; Maix, R.K.; Weber, H.W. [Atomic Institute of the Austrian Universities, 1020 Vienna (Austria)

2004-06-28

208

Performance of an Anaerobic Baffled Reactor (ABR) in treatment of cassava wastewater  

PubMed Central

The performance of an anaerobic baffled reactor (ABR) was evaluated in the treatment of cassava wastewater, a pollutant residue. An ABR divided in four equal volume compartments (total volume 4L) and operated at 35ºC was used in cassava wastewater treatment. Feed tank chemical oxygen demand (COD) was varied from 2000 to 7000 mg L-1 and it was evaluated the most appropriated hydraulic retention time (HRT) for the best performance on COD removal. The ABR was evaluated by analysis of COD (colorimetric method), pH, turbidity, total and volatile solids, alkalinity and acidity. Principal component analysis (PCA) was carried to better understand data obtained. The system showed buffering ability as acidity decreased along compartments while alkalinity and pH values were increased. There was particulate material retention and COD removal varied from 83 to 92% for HRT of 3.5 days. PMID:24031316

Ferraz, Fernanda M.; Bruni, Aline T.; Del Bianchi, Vanildo L.

2009-01-01

209

Greek research reactor performance characteristics after addition of beryllium reflector and LEU fuel  

SciTech Connect

The GRR-1 is a 5-MW pool-type, light-water-moderated and-cooled reactor fueled with MTR-type fuel elements. Recently received Be reflector blocks will soon be added to the core to add additional reactivity until fresh LEU fuel arrives. REBUS-3 xy fuel cycle analyses, using burnup dependent cross sections, were performed to assist in fuel management decisions for the water- and Be-reflected HEU nonequilibrium cores. Cross sections generated by EPRI-CELL have been benchmarked to identical VIM Monte Carlo models. The size of the Be-reflected LEU core has been reduced to 30 elements compared to 35 for the HEU water-reflected core, and an equilibrium cycle calculation has been performed.

Deen, J.R.; Snelgrove, J.L. [Argonne National Lab., IL (United States); Papastergiou, C. [National Center for Scientific Research, Athens (Greece)

1992-12-31

210

Greek research reactor performance characteristics after addition of beryllium reflector and LEU fuel  

SciTech Connect

The GRR-1 is a 5-MW pool-type, light-water-moderated and-cooled reactor fueled with MTR-type fuel elements. Recently received Be reflector blocks will soon be added to the core to add additional reactivity until fresh LEU fuel arrives. REBUS-3 xy fuel cycle analyses, using burnup dependent cross sections, were performed to assist in fuel management decisions for the water- and Be-reflected HEU nonequilibrium cores. Cross sections generated by EPRI-CELL have been benchmarked to identical VIM Monte Carlo models. The size of the Be-reflected LEU core has been reduced to 30 elements compared to 35 for the HEU water-reflected core, and an equilibrium cycle calculation has been performed.

Deen, J.R.; Snelgrove, J.L. (Argonne National Lab., IL (United States)); Papastergiou, C. (National Center for Scientific Research, Athens (Greece))

1992-01-01

211

Performance of a catalytic reactor at simulated gas turbine combustor operating conditions  

NASA Technical Reports Server (NTRS)

The performance of a catalytic reactor 12 cm in diameter and 17 cm long was evaluated at simulated gas turbine combustor operating conditions using premixed propane and air. Inlet temperatures of 600 and 800 K, pressures of 3 and 6 atm, and reference velocities of 9 to 30 m/s were tested. Data were taken for equivalence ratios as high as 0.43. The operating range was limited on the low-temperature side by very poor efficiency; the minimum exit temperature for good performance ranged from 1400 to 1600 K depending on inlet conditions. As exit temperatures were raised above this minimum, emissions of unburned hydrocarbons decreased, carbon monoxide emissions became generally less than 1 g CO/kg fuel, and nitrogen oxides were less than about 0.1 g NO2/kg fuel.

Anderson, D. N.; Tacina, R. R.; Mroz, T. S.

1975-01-01

212

The effect of shock loading on the performance of a thermophilic anaerobic contact reactor at constant organic loading rate  

PubMed Central

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

2014-01-01

213

Influence of the ratio of the initial substrate concentration to biomass concentration on the performance of a sequencing batch reactor  

Microsoft Academic Search

Biomass behaviour and COD removal in a benchscale activated sludge reactor have been studied alternating anaerobic and aerobic conditions. Particular attention has been paid to the influence of the ratio of the initial substrate concentration (S0) to the initial biomass concentration (X0) on the reactor performance. Tests at very low ratios (S0\\/X0S0\\/X0=0.5). Under conditions of total suppression of cell duplication,

R. Ghigliazza; A. Lodi; A. Converti; C. Nicolella; M. Rovatti

1996-01-01

214

Effect of shock and mixed loading on the performance of SND based sequencing batch reactors (SBR) degrading nitrophenols.  

PubMed

The effect of nitrophenolic shock loads on the performance of three lab scale SBRs was studied using a synthetic feed. Nitrophenols were biotransformed by Simultaneous heterotrophic Nitrification and aerobic Denitrification (SND) using a specially designed single sludge biomass containing Thiosphaera pantotropha. Reactors R1, R2 and R3 were fed with 200mg/L concentration of 4-nitrophenol (4-NP), 2,4-dinitrophenol (2,4-DNP), and 2,4,6-trinitrophenol (2,4,6-TNP) whereas reactor R was used as a background control. Three nitrophenolic shock loadings of 400, 600 and 800 mg/Ld were administrated by increasing the influent nitrophenolic concentration while keeping the hydraulic retention time as 48 h. The shocks were given continuously for a period of 4 days before switching back to normal nitrophenolic loading (200mg/Ld). The reactors were allowed to recover to normal performance level before administrating the next nitrophenolic shock load. The study showed that a nitrophenolic shock load, as high as 600 mg/Ld was completely degraded by the 4-NP & 2,4-DNP bioreactors while almost half degraded by the 2,4,6-TNP bioreactor without affecting the reactor's performance irreversibly. After resuming the normal nitrophenolic loading, it took almost 8-10 days for the reactors to recover from the shock effect. The study was further extended to evaluate the maximum possible mixed nitrophenolic loading (4-NP:2,4-DNP:2,4,6-TNP 1:1:1) to which a reactor (R3) containing 2,4,6-TNP acclimated single sludge biomass can be exposed without hampering the reactor performance irreversibly. The reactor was able to achieve pseudo-steady-state at a mixed nitrophenolic loading of 300 mg/Ld with more than 90% removal of all the three nitrophenols, but could remove half of the mixed nitrophenolic loading of 600 mg/Ld. PMID:22386885

Kulkarni, P M

2012-05-01

215

Performance evaluation and kinetic modeling of the start-up of a UASB reactor treating municipal wastewater at low temperature  

Microsoft Academic Search

A kinetic modeling-based study was carried out to evaluate the start-up performance of a 10-L up-flow anaerobic sludge blanket\\u000a (UASB) reactor treating municipal wastewater under different organic and hydraulic loading conditions. The reactor was operated\\u000a for 105 days (around 4 months) below 20 °C and with three different hydraulic retention times of 24, 12 and 5 h. Imposed volumetric\\u000a organic loading rates (OLR) ranged

F. Ilter Turkdogan-Aydinol; Kaan Yetilmezsoy; Sezen Comez; Hurrem Bayhan

2011-01-01

216

Performance and radiological analyses of a space reactor power system deployed into a 1000–3000 km earth orbit  

Microsoft Academic Search

This paper presents the results of performance and radiological analyses of a space reactor power system to support space-based, radar satellites in a 1000–3000km orbit for global civilian air and ocean traffic control. The power system with six primary and secondary loops to avoid single point failures in reactor cooling and energy conversion employs a sectored, liquid NaK-78 cooled fission

Mohamed S. El-Genk; Timothy M. Schriener

2010-01-01

217

POTENTIAL OF BIOGAS PRODUCTION IN SUSTAINABLE BIOREFINERY CONCEPTS  

Microsoft Academic Search

Currently, biogas production is mainly based on the anaerobic digestion of single energy crops. In the future, biogas production from energy crops will increase and will have to be based on a wide range of energy crops that are grown in versatile, sustainable crop rotations. In addition, more by-products products from the agricultural, food and energy industry need to be

Alexander Bauer; Regina Hrbek; Barbara Amon; Vitaliy Kryvoruchko; Vitomir Bodiroza; Helmut Wagentristl; Werner Zollitsch; Bettina Liebmanne; Martin Pfeffere; Anton Friedle; Thomas Amon

218

An Introduction to Biogas Production on the Farm.  

ERIC Educational Resources Information Center

This three-section report provides introductory information about biogas production and its application to farm environments. The first section discusses the various components of a biogas production system (a system that converts organic wastes into a usable form of energy), explains the system's benefits and liabilities, and provides a brief…

National Center for Appropriate Technology, Butte, MT.

219

Plug flow digestors for biogas generation from leaf biomass  

Microsoft Academic Search

The low, family level availability of animal dung in rural Indian families restricts the spread of biogas technology. This has warranted the design and development of novel biogas plants for other biomass feedstocks. The plug-flow digestors discussed in this paper circumvent the problems associated with floating of biomass feedstocks and enable a semi-continuous operation. The long term operation of such

K. S Jagadish; H. N Chanakya; P Rajabapaiah; V Anand

1998-01-01

220

Technical–economical analysis of the Saveh biogas power plant  

Microsoft Academic Search

The resource limitation of fossil fuels and the problems arising from their combustion has led to widespread research on the accessibility of new and renewable energy resources. Solar, wind, thermal and hydro sources, and finally biogas are among these renewable energy resources. But what makes biogas distinct from other renewable energies is its importance in controlling and collecting organic waste

Giti Taleghani; Akbar Shabani Kia

2005-01-01

221

Energy balance model of a SOFC cogenerator operated with biogas  

Microsoft Academic Search

A small cogeneration system based on a Solid Oxide Fuel Cell (SOFC) fed on the renewable energy source biogas is presented. An existing farm biogas production site (35m3 per day), currently equipped with a SOFC demonstration stack, is taken for reference. A process flow diagram was defined in a software package allowing to vary system operating parameters like the fuel

Jan Van herle; F. Maréchal; S. Leuenberger; D. Favrat

2003-01-01

222

Biogas Purification Process to Increase Gen—Set Efficiency  

NASA Astrophysics Data System (ADS)

Because of global issue about limited energy, biogas was one of alternative energy and save energy in the world which produced from biomass especially from cow manure. Most of biogas which produced from cow manure contains 40-75% methane as energy resources and another gas as impurities. Methane concentration of biogas has relation with biogas energy value, especially for application as fuel of electricity conversion using gen-set. For increasing gen-set efficiency can be held by increasing methane concentration of biogas using biogas purification process. Biogas purification process can be held by adsorption system which using activated zeolite as absorber. After biogas through the purification system, methane concentration was increasing and impacting to gen-set efficiency especially voltage value was increasing until 22 times in average better than without purification and keeping power stability, so it will produce electricity conversion until 39,07% of practical and 38,09% of equation calculation from maximum electric power output of gen-set.

Krido Wahono, Satriyo; Maryana, Roni; Kismurtono, M.

2009-09-01

223

DEVELOPMENT OF AN AFFORDABLE FAMILY-SCALE BIOGAS GENERATOR  

EPA Science Inventory

From laboratory experiments we calculated that our system would have to deliver 262 liters/hr of biogas to cook a meal. Biogas produced by slurries of various wastes was measured with a two liter bench-top digester system designed by the team. Gas volume was measured by displa...

224

Energy Efficiency of Biogas Produced from Different Biomass Sources  

NASA Astrophysics Data System (ADS)

Malaysia has different sources of biomass like palm oil waste, agricultural waste, cow dung, sewage waste and landfill sites, which can be used to produce biogas and as a source of energy. Depending on the type of biomass, the biogas produced can have different calorific value. At the same time the energy, being used to produce biogas is dependent on transportation distance, means of transportation, conversion techniques and for handling of raw materials and digested residues. An energy systems analysis approach based on literature is applied to calculate the energy efficiency of biogas produced from biomass. Basically, the methodology is comprised of collecting data, proposing locations and estimating the energy input needed to produce biogas and output obtained from the generated biogas. The study showed that palm oil and municipal solid waste is two potential sources of biomass. The energy efficiency of biogas produced from palm oil residues and municipal solid wastes is 1.70 and 3.33 respectively. Municipal solid wastes have the higher energy efficiency due to less transportation distance and electricity consumption. Despite the inherent uncertainties in the calculations, it can be concluded that the energy potential to use biomass for biogas production is a promising alternative.

Begum, Shahida; Nazri, A. H.

2013-06-01

225

Preliminary experimental results of Sewage Sludge (SS) Co-digestion with Palm Oil Mill Effluent (POME) for Enhanced Biogas Production in Laboratory Scale Anaerobic Digester  

NASA Astrophysics Data System (ADS)

An investigation on the feasibility of co-digesting Sewage Sludge with Palm Oil Mill Effluent for enhancing the biogas production and the corresponding effect of the co-digestion substrate ratio on the biogas production has been evaluated. Anaerobic co-digestion of POME with SS was performed at ratios of 100:0, 70:30, 60:40 and 0:100 to find the optimum blend required for enhanced waste digestion and biogas production. Single stage batch digestion was carried out for 12 days in a laboratory scale anaerobic digester. Co-digestion of sludge's at the 70:30 proportion resulted in optimal COD and C: N ratio which subsequently recorded the highest performance with regards to biogas production at 28.1 L's compared to the 1.98 L's of biogas produced from digestion of SS alone. From the results obtained, it is evident that co-digestion of POME and SS is an attractive option to be explored for enhancement of biogas production in anaerobic digesters.

Sivasankari, R.; Kumaran, P.; Normanbhay, Saifuddin; Halim Shamsuddin, Abd

2013-06-01

226

Performance of permeable media rotating reactors used for pretreatment of wastewaters.  

PubMed

The impact of organic loading rate (OLR) on carbonaceous materials and ammonia removal was assessed in bench scale rotating media biofilm reactors treating real wastewater. Media composition influences biofilm structure and therefore performance. Here, plastic mesh, reticulated coarse foam and fine foam media were operated concurrently at OLRs of 15, 35 and 60 g sCOD m(-2)d(-1) in three bench scale shaft mounted advanced reactor technology (SMART) reactors. The sCOD removal rate increased with loading from 6 to 25 g sCOD m(-2)d(-1) (P < 0.001). At 35 g BOD5m(-2)d(-1), more than double the arbitrary OLR limit of normal nitrifying conditions (15 g BOD5m(-2)d(-1)); the removal efficiency of NH(4)-N was 82 ± 5, 27 ± 19 and 39 ± 8% for the mesh, coarse foam and fine foam media, respectively. Increasing the OLR to 35 gm(-2)d(-1) decreased NH(4)-N removal efficiency to 38 ± 6, 21 ± 4 and 21 ± 6%, respectively. The mesh media achieved the highest stable NH(4)(+)-N removal rate of 6.5 ± 1.6 gm(-2)d(-1) at a sCOD loading of 35 g sCOD m(-2)d(-1). Viable bacterial numbers decreased with increasing OLR from 2 × 10(10)-4 × 10(9) cells per ml of biofilm from the low to high loading, suggesting an accumulation of inert non-viable biomass with higher OLR. Increasing the OLR in permeable media is of practical benefit for high rate carbonaceous materials and ammonia removal in the pretreatment of wastewater. PMID:24804669

Hassard, F; Cartmell, E; Biddle, J; Stephenson, T

2014-01-01

227

Full-scale sequencing batch reactor (SBR) for domestic wastewater: performance and diversity of microbial communities.  

PubMed

This work describes the performance and microbial diversity in a sequencing batch reactor of a decentralized full-scale system for urban wastewater treatment under limited aeration. The removal efficiency was: 83% for soluble chemical oxygen demand (SCOD), 60% for N-NH4(+), 70% for total suspended solids (TSS) and 80% for volatile suspended solids (VSS). The biomass concentration had a maximum value around 8.7gVSSL(-1) for organic load rate of 0.6gCODL(-1)d(-1). The food/microorganism ratios showed average of 0.2gCOD/gVSSd. The sludge bacterial flocs were formed an irregular arrangement with organisms attached such as Euglypha sp. and pedunculate ciliates. It was observed the presence of Bacteria domains including Nitrosomonas spp., Nitrobacter spp., Nitrospira and C. "Accumulibacter" cluster. The DPAO activity was 70%. Denaturing gradient gel electrophoresis showed changes in ribotype number over biological treatment time among the groups observed being some are linked to nutrient removal. The reactor showed viability to treat domestic wastewater. PMID:23411457

Fernandes, Heloísa; Jungles, Mariele K; Hoffmann, Heike; Antonio, Regina V; Costa, Rejane H R

2013-03-01

228

Effect of corrosion of steel elements on the treatment of dairy wastewater in a UASB reactor.  

PubMed

Experiments were performed in parallel using two laboratory upflow anaerobic sludge blanket (UASB) reactors. One of the two reactors was packed with spiral elements made of steel wire with 48% iron content in order to examine the influence of the steel elements on the chemical oxygen demand (COD) and efficiency of phosphorus removal from synthetically prepared dairy wastewater. A strong relationship was found between anaerobic corrosion and efficiency of phosphorus removal. Phosphorus removal in the reactor packed with steel elements was between 16.4% and 64.4% higher than without the steel elements present. The anaerobic corrosion process improved COD removal efficiency by 1.0-3.1%, which was statistically significant. When steel elements were present the methane content of the biogas was increased by 6.7%. Increasing the organic loading rate had a strong effect on the anaerobic efficiency of the dairy wastewater treatment. PMID:20540419

J?drzejewska Cici?ska, M; Krzemieniewski, M

2010-05-01

229

Advanced Concepts for Pressure-Channel Reactors: Modularity, Performance and Safety  

NASA Astrophysics Data System (ADS)

Based on an analysis of the development of advanced concepts for pressure-tube reactor technology, we adapt and adopt the pressure-tube reactor advantage of modularity, so that the subdivided core has the potential for optimization of the core, safety, fuel cycle and thermal performance independently, while retaining passive safety features. In addition, by adopting supercritical water-cooling, the logical developments from existing supercritical turbine technology and “steam” systems can be utilized. Supercritical and ultra-supercritical boilers and turbines have been operating for some time in coal-fired power plants. Using coolant outlet temperatures of about 625°C achieves operating plant thermal efficiencies in the order of 45-48%, using a direct turbine cycle. In addition, by using reheat channels, the plant has the potential to produce low-cost process heat, in amounts that are customer and market dependent. The use of reheat systems further increases the overall thermal efficiency to 55% and beyond. With the flexibility of a range of plant sizes suitable for both small (400 MWe) and large (1400 MWe) electric grids, and the ability for co-generation of electric power, process heat, and hydrogen, the concept is competitive. The choice of core power, reheat channel number and exit temperature are all set by customer and materials requirements. The pressure channel is a key technology that is needed to make use of supercritical water (SCW) in CANDU®1 reactors feasible. By optimizing the fuel bundle and fuel channel, convection and conduction assure heat removal using passive-moderator cooling. Potential for severe core damage can be almost eliminated, even without the necessity of activating the emergency-cooling systems. The small size of containment structure lends itself to a small footprint, impacts economics and building techniques. Design features related to Canadian concepts are discussed in this paper. The main conclusion is that development of SCW pressure-channel nuclear reactors is feasible and significant benefits can be expected over other thermal-energy systems.

Duffey, Romney B.; Pioro, Igor L.; Kuran, Sermet

230

Improvement of a grass-clover silage-fed biogas process by the addition of cobalt  

Microsoft Academic Search

Batch assays were performed with samples from a silage-fed mesophilic biogas process accumulating acetate to examine if the addition of single trace elements (iron, nickel, cobalt and molybdenum) or a mixture of trace elements could improve the process. The results from the batch assays led to the addition of cobalt to reach a concentration of 0.2 mg L?1. This made

Å. Jarvis; Å. Nordberg; T. Jarlsvik; B. Mathisen; B. H. Svensson

1997-01-01

231

Environmental assessment of biogas co- or tri-generation units by life cycle analysis methodology  

Microsoft Academic Search

A life cycle analysis performed on biogas co- or tri-generation units shows that the environmental impact depends on the fraction of heat (or cold) used, the distance for crops collection, the efficiencies of the unit and on the NOx emissions. A high efficiency unit (?el=0.4 and ?g=0.8) and low NOx content (80mg\\/Nm3) based on 20km crops collection will save CO2

C. Chevalier; F. Meunier

2005-01-01

232

Process flow model of solid oxide fuel cell system supplied with sewage biogas  

Microsoft Academic Search

A model for a 100kW class solid oxide fuel cell (SOFC) system running on biogas from a sewage sludge digestion plant was implemented in a process flow scheme using external steam reforming. The model stack consisted of planar anode supported cells operated at 800°C displaying state-of-the-art electrochemical performance (0.15W\\/cm2 at 80% fuel utilisation). Real annual data from an existing sewage

J Van herle; F Maréchal; S Leuenberger; Y Membrez; O Bucheli; D Favrat

2004-01-01

233

Management of various organic fractions of municipal solid waste via recourse to VFA and biogas generation.  

PubMed

A hybrid anaerobic solid-liquid system was used for anaerobic digestion of organic fraction of municipal solid waste (OFMSW) consisting of mixed food + fruit waste and vegetable waste. Hydrolysis and acidogenesis potential of the above wastes were evaluated with the aim of producing value-added products in the form of volatile fatty acids (VFAs) and biogas recovery. Efficient hydrolysis and acidogenesis of mixed food + fruit waste was observed at a hydraulic retention time (HRT) of 1-3 d with a five-fold increase in soluble chemical oxygen demand (SCOD) followed by VFA production consisting of 50-75% acetic acid. Longer time was required for hydrolysis of vegetable waste with optimum hydrolysis and SCOD generation at 9 d HRT followed by VFA synthesis consisting of 45% acetic acid. Higher inoculum:substrate ratios resulted in improved hydrolysis and acidogenesis rates for vegetable waste in shorter time of 6 d with higher VFA production and increase in acetic acid content to 70%. When acidogenic leachate was fed into methanogenic reactors, detectable biogas production was observed after 25 d with 37-53% SCOD removal from leachate from mixed food + fruit waste and methane production of 0.066-0.1 L g(-1) SCOD removed and methane content of 38%. Though biogas yield from acidogenic leachate from vegetable waste was lower, nearly 94% volatile solids (VS) removal was observed in the reactors thereby providing methane yield of 0.13-0.21 L g(-1) VS consumed. Thus, the study provided a method for generation of value-added products from an otherwise misplaced resource in the form of OFMSW. PMID:24350462

Khardenavis, Anshuman Arun; Wang, Jing Yuan; Ng, Wun Jern; Purohit, Hemant J

2013-01-01

234

Effect of Aeration on the Performance of a Simulated Landfilling Reactor Stabilizing Municipal Solid Wastes  

Microsoft Academic Search

In this study, the effects of intermittent aeration on the anaerobic treatment of domestic solid waste and leachate characteristics were investigated in three simulated landfill anaerobic bioreactors. All of the reactors were operated with leachate recirculation and recirculation rate was 300 mL\\/d. All the reactors were loaded with solid waste having different operational mode. The first reactor was operated with recirculation

Osman Nuri A?da?; Delia Teresa Sponza

2004-01-01

235

Enhancement of biogas production by co-digestion of potato pulp with cow manure in a CSTR system.  

PubMed

Anaerobic digestion (AD) process is a well-established method to generate energy from the organic wastes both from the environmental and economical perspectives. The purpose of present study is to evaluate energy production from potato wastes by incorporating cow manure into the process. Firstly, a laboratory pilot of one-stage biogas production was designed and built according to continuously stirred tank reactor (CSTR) system. The setup was able to automatically control the environmental conditions of the process including temperature, duration, and rate of stirring. AD experiment was exclusively performed on co-digestion of potato peel (PP) and cow manure (CM) in three levels of mixing ratio including 20:80, 50:50, 80:20 (PP:CM), and 0:100 as control treatment based on the volatile solid (VS) weight without adding initial inoculums. After hydraulic retention time (HRT) of 50 days on average 193, 256, 348, and 149 norm liter (LN) (kg VS)(-1), methane was produced for different mixing ratios, respectively. Statistical analysis shows that these gas productions are significantly different. The average energy was determined based on the produced methane which was about 2.8 kWh (kg VS)(-1), implying a significant energy production potential. The average chemical oxygen demand (COD) removal of treatments was about 61%, showing that it can be leached significantly with high organic matter by the employed pilot. The energy efficiency of 92% of the process also showed the optimum control of the process by the pilot. PMID:24894660

Sanaei-Moghadam, Akbar; Abbaspour-Fard, Mohammad Hossein; Aghel, Hasan; Aghkhani, Mohammad Hossein; Abedini-Torghabeh, Javad

2014-08-01

236

Cost analysis of concepts for a demand oriented biogas supply for flexible power generation.  

PubMed

With the share of intermittent renewable energies within the electricity system rising, balancing services from dispatchable power plants are of increasing importance. Highlighting the importance of the need to keeping fuel costs for flexible power generation to a minimum, the study aims to identify favourable biogas plant configurations, supplying biogas on demand. A cost analysis of five configurations based on biogas storing and flexible biogas production concepts has been carried out. Results show that additional flexibility costs for a biogas supply of 8h per day range between 2€ and 11€MWh(-1) and for a 72h period without biogas demand from 9€ to 19€MWh(-1). While biogas storage concepts were identified as favourable short term supply configurations, flexible biogas production concepts profit from reduced storage requirements at plants with large biogas production capacities or for periods of several hours without biogas demand. PMID:25146313

Hahn, Henning; Ganagin, Waldemar; Hartmann, Kilian; Wachendorf, Michael

2014-10-01

237

Benefits of supplementing an industrial waste anaerobic digester with energy crops for increased biogas production  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer This study demonstrates the feasibility of co-digestion food industrial waste with energy crops. Black-Right-Pointing-Pointer Laboratory batch co-digestion led to improved methane yield and carbon to nitrogen ratio as compared to mono-digestion of industrial waste. Black-Right-Pointing-Pointer Co-digestion was also seen as a means of degrading energy crops with nutrients addition as crops are poor in nutrients. Black-Right-Pointing-Pointer Batch co-digestion methane yields were used to predict co-digestion methane yield in full scale operation. Black-Right-Pointing-Pointer It was concluded that co-digestion led an over all economically viable process and ensured a constant supply of feedstock. - Abstract: Currently, there is increasing competition for waste as feedstock for the growing number of biogas plants. This has led to fluctuation in feedstock supply and biogas plants being operated below maximum capacity. The feasibility of supplementing a protein/lipid-rich industrial waste (pig manure, slaughterhouse waste, food processing and poultry waste) mesophilic anaerobic digester with carbohydrate-rich energy crops (hemp, maize and triticale) was therefore studied in laboratory scale batch and continuous stirred tank reactors (CSTR) with a view to scale-up to a commercial biogas process. Co-digesting industrial waste and crops led to significant improvement in methane yield per ton of feedstock and carbon-to-nitrogen ratio as compared to digestion of the industrial waste alone. Biogas production from crops in combination with industrial waste also avoids the need for micronutrients normally required in crop digestion. The batch co-digestion methane yields were used to predict co-digestion methane yield in full scale operation. This was done based on the ratio of methane yields observed for laboratory batch and CSTR experiments compared to full scale CSTR digestion of industrial waste. The economy of crop-based biogas production is limited under Swedish conditions; therefore, adding crops to existing industrial waste digestion could be a viable alternative to ensure a constant/reliable supply of feedstock to the anaerobic digester.

Nges, Ivo Achu, E-mail: Nges.Ivo_Achu@biotek.lu.se [Department of Biotechnology, Lund University, P.O. Box 124, SE 221 00 Lund (Sweden); Escobar, Federico; Fu Xinmei; Bjoernsson, Lovisa [Department of Biotechnology, Lund University, P.O. Box 124, SE 221 00 Lund (Sweden)

2012-01-15

238

Treatment of wastewater from coffee bean processing in anaerobic fixed bed reactors with different support materials: performance and kinetic modeling.  

PubMed

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. PMID:22609965

Fia, Fátima R L; Matos, Antonio T; Borges, Alisson C; Fia, Ronaldo; Cecon, Paulo R

2012-10-15

239

Analysis of problems with dry fermentation process for biogas production  

NASA Astrophysics Data System (ADS)

The technology of dry anaerobic fermentation is still meeting with some scepticism, and therefore in most biogas plants are used wet fermentation technology. Fermentation process would be not complete without an optimal controlled condition: dry matter content, density, pH, and in particular the reaction temperature. If is distrust of dry fermentation eligible it was on the workplace of the Department of Power Engineering at University of Zilina built an experimental small-scale biogas station that allows analysis of optimal parameters of the dry anaerobic fermentation, in particular, however, affect the reaction temperature on yield and quality of biogas.

Pilát, Peter; Patsch, Marek; Janda?ka, Jozef

2012-04-01

240

Correlation between biogas yield and chemical composition of energy crops.  

PubMed

The scope of this study was to investigate the influence of the chemical composition of energy crops on biogas and methane yield. In total, 41 different plants were analyzed in batch test and their chemical composition was determined. For acid detergent lignin (ADL) content below 10% of total solids, a significant negative correlation for biogas and methane yields (r?-0.90) was observed. Based on a simple regression analysis, more than 80% of the sample variation can be explained through ADL. Based on a principal component analysis and multiple regression analysis, ADL and hemicellulose are suggested as suitable model variables for biogas yield potential predictions across plant species. PMID:25443623

Dandikas, V; Heuwinkel, H; Lichti, F; Drewes, J E; Koch, K

2014-12-01

241

Comparison of different procedures to stabilize biogas formation after process failure in a thermophilic waste digestion system: Influence of aggregate formation on process stability  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Mechanism of process recovery with calcium oxide. Black-Right-Pointing-Pointer Formation of insoluble calcium salts with long chain fatty acids and phosphate. Black-Right-Pointing-Pointer Adsorption of VFAs by the precipitates resulting in the formation of aggregates. Black-Right-Pointing-Pointer Acid uptake and phosphate release by the phosphate-accumulating organisms. Black-Right-Pointing-Pointer Microbial degradation of volatile fatty acids in the aggregates. - Abstract: Following a process failure in a full-scale biogas reactor, different counter measures were undertaken to stabilize the process of biogas formation, including the reduction of the organic loading rate, the addition of sodium hydroxide (NaOH), and the introduction of calcium oxide (CaO). Corresponding to the results of the process recovery in the full-scale digester, laboratory experiments showed that CaO was more capable of stabilizing the process than NaOH. While both additives were able to raise the pH to a neutral milieu (pH > 7.0), the formation of aggregates was observed particularly when CaO was used as the additive. Scanning electron microscopy investigations revealed calcium phosphate compounds in the core of the aggregates. Phosphate seemed to be released by phosphorus-accumulating organisms, when volatile fatty acids accumulated. The calcium, which was charged by the CaO addition, formed insoluble salts with long chain fatty acids, and caused the precipitation of calcium phosphate compounds. These aggregates were surrounded by a white layer of carbon rich organic matter, probably consisting of volatile fatty acids. Thus, during the process recovery with CaO, the decrease in the amount of accumulated acids in the liquid phase was likely enabled by (1) the formation of insoluble calcium salts with long chain fatty acids, (2) the adsorption of volatile fatty acids by the precipitates, (3) the acid uptake by phosphorus-accumulating organisms and (4) the degradation of volatile fatty acids in the aggregates. Furthermore, this mechanism enabled a stable process performance after re-activation of biogas production. In contrast, during the counter measure with NaOH aggregate formation was only minor resulting in a rapid process failure subsequent the increase of the organic loading rate.

Kleyboecker, A.; Liebrich, M.; Kasina, M. [Microbial GeoEngineering, Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany); Kraume, M. [Chemical and Process Engineering, Technical University Berlin, 10623 Berlin (Germany); Wittmaier, M. [Institute for Recycling and Environmental Protection, Bremen University of Applied Sciences, 28199 Bremen (Germany); Wuerdemann, H., E-mail: wuerdemann@gfz-potsdam.de [Microbial GeoEngineering, Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany)

2012-06-15

242

Performance of sequencing batch biofilm reactors with different control systems in treating synthetic municipal wastewater.  

PubMed

This study aimed to evaluate the performances of sequencing batch biofilm reactors (SBBRs) in removing nitrogen and phosphorus from synthetic municipal wastewater with different carbon to total nitrogen (C/N) ratios. The effect of control systems, including an intelligent control system (ICS) and conventional timer control system (TCS) on the performance of SBBRs was also investigated. When C/N ratios were 10.0, 5.0 and 3.3, the average COD removal efficiencies in the ICS-SBBR reached 87.7%, 92.3% and 97.6%, while total phosphorous (TP) removals reached 95.0%, 97.0% and 97.2%. When the C/N ratio was 5.0, the TN removal efficiency was 81.0% under ICS and 65.4% under TCS. Moreover, compared with TCS-SBBR, both reaction time and aeration time were shortened by 180 min and 157 min, respectively, in the ICS-SBBR. Therefore, the ICS-SBBR has potential in practical applications for significant nitrogen and phosphorus removal and energy savings. PMID:22093972

Jin, Yunxiao; Ding, Dahu; Feng, Chuanping; Tong, Shuang; Suemura, Takashi; Zhang, Feng

2012-01-01

243

Advanced Fuels Campaign Light Water Reactor Accident Tolerant Fuel Performance Metrics Executive Summary  

SciTech Connect

Research and development (R&D) activities on advanced, higher performance Light Water Reactor (LWR) fuels have been ongoing for the last few years. Following the unfortunate March 2011 events at the Fukushima Nuclear Power Plant in Japan, the R&D shifted toward enhancing the accident tolerance of LWRs. Qualitative attributes for fuels with enhanced accident tolerance, such as improved reaction kinetics with steam resulting in slower hydrogen generation rate, provide guidance for the design and development of fuels and cladding with enhanced accident tolerance. A common set of technical metrics should be established to aid in the optimization and down selection of candidate designs on a more quantitative basis. “Metrics” describe a set of technical bases by which multiple concepts can be fairly evaluated against a common baseline and against one another. This report describes a proposed technical evaluation methodology that can be applied to evaluate the ability of each concept to meet performance and safety goals relative to the current UO2 – zirconium alloy system and relative to one another. The resultant ranked evaluation can then inform concept down-selection, such that the most promising accident tolerant fuel design option(s) can continue to be developed toward qualification.

Shannon Bragg-Sitton

2014-02-01

244

Experimental Evaluation of the Thermal Performance of a Water Shield for a Surface Power Reactor  

NASA Technical Reports Server (NTRS)

A water based shielding system is being investigated for use on initial lunar surface power systems. The use of water may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. Natural convection in a representative lunar surface reactor shield design is evaluated at various power levels in the Water Shield Testbed (WST) at the NASA Marshall Space Flight Center. The experimental data from the WST is used to anchor a CFD model. Performance of a water shield on the lunar surface is then predicted by CFD models anchored to test data. The accompanying viewgraph presentation includes the following topics: 1) Testbed Configuration; 2) Core Heater Placement and Instrumentation; 3) Thermocouple Placement; 4) Core Thermocouple Placement; 5) Outer Tank Thermocouple Placement; 6) Integrated Testbed; 7) Methodology; 8) Experimental Results: Core Temperatures; 9) Experimental Results; Outer Tank Temperatures; 10) CFD Modeling; 11) CFD Model: Anchored to Experimental Results (1-g); 12) CFD MOdel: Prediction for 1/6-g; and 13) CFD Model: Comparison of 1-g to 1/6-g.

Pearson, J. Boise; Stewart, Eric T.; Reid, Robert S.

2007-01-01

245

Impact of coexistence of flocs and biofilm on performance of combined nitritation-anammox granular sludge reactors.  

PubMed

Nitrogen (N) removal from high-strength wastewater can be accomplished in single-stage combined nitritation-anammox reactors with suspended growth biomass composed of floccular sludge, granular sludge, or of any mix of these 2 different sludge fractions. To date, the influence of floccular biomass on granular sludge reactor performance and stability has not been investigated experimentally or numerically. To address this knowledge gap, two 1D multi-species models were developed in Aquasim to assess the importance of small levels of flocs in putatively granular sludge combined nitritation-anammox reactors for different bulk oxygen concentrations and organics loads. The models included the growth and decay of aerobic ammonium-oxidizing organism (AOO), nitrite-oxidizing organisms (NOO), heterotrophic organisms (OHO), and anammox organisms (AMO) in exclusively granular sludge reactors, and in granular sludge reactors with small levels (?5% of total biomass) of flocs. While maximum N removal efficiencies were similar for both model structures, floc addition led to a lower optimal dissolved oxygen concentration (DO) as well as a narrower maximum N removal peak, suggesting that small levels of floccular material may decrease process robustness to bulk oxygen changes. For some DO levels, this led to drastic efficiency drops. Furthermore, floc addition also led to substantial segregation in activity and microbial population distribution, with AOO, NOO and OHO concentrated in flocs and AMO concentrated in granules. Increased organic loading (COD:N = 4:3) improved maximum N removal efficiency in both model structures, but yielded substantially different predictions for optimal DO setpoint and process robustness to variations in DO. Taken together, our results indicate that even small levels of floccular biomass in biofilm reactors can have profound implications for reactor performance and optimization and for segregation of linked microbial processes, and suggest that the common practice of neglecting small levels of floccular material in biofilm models and in practice may lead to erroneous predictions. PMID:25462723

Hubaux, N; Wells, G; Morgenroth, E

2014-10-01

246

The performance of high-loading composite anammox reactor and its long-term recovery from extreme substrates inhibition.  

PubMed

A composite reactor combined with granule and biofilm in one single SBR was developed for high-rate anammox operation. Low activity flocculent inoculum was used as seed sludge and the nitrogen loading rate reached 10.62kgNm(-3)d(-1) after 93days' operation. Subsequently, the performance of high-loading anammox reactor under fluctuation condition was investigated. Due to the extremely short hydraulic retention time and high-strength substrates, the reactor presented dramatic substrates accumulation which resulted in severe inhibition subsequently. Nevertheless, the composite reactor presented significant recovery potential even after biomass hydrolysis caused by inhibition, mainly due to the protection and promotion supplied by biofilm. Besides, granules were gradually formed and accumulated from the flocculent sludge directly during the recovery operation, further elevating the reactor performance. The nitrogen loading rate and corresponding nitrogen removal rate achieved 20.30 and 18.01kgNm(-3)d(-1) with total nitrogen in the influent of 1500mg/l finally. PMID:25233476

Zhao, Jian; Zuo, Jiane; Li, Peng; Lin, Jia

2014-11-01

247

The effect of polymer addition on granulation in an anaerobic baffled reactor (ABR). Part I: process performance  

Microsoft Academic Search

The stability and performance of an anaerobic baffled reactor (ABR) treating an ice-cream wastewater at several organic loading rates have been investigated. Specifically, it was determined whether an ABR would promote phase separation and if a polymer additive was capable of enhancing granule formation in an ABR. In order to achieve these goals, two ABRs, having identical dimensions and configurations,

S Uyanik; P. J Sallis; G. K Anderson

2002-01-01

248

Process flow model of solid oxide fuel cell system supplied with sewage biogas  

NASA Astrophysics Data System (ADS)

A model for a 100 kW class solid oxide fuel cell (SOFC) system running on biogas from a sewage sludge digestion plant was implemented in a process flow scheme using external steam reforming. The model stack consisted of planar anode supported cells operated at 800 °C displaying state-of-the-art electrochemical performance (0.15 W/cm 2 at 80% fuel utilisation). Real annual data from an existing sewage plant were used as input to the model. From the input of 43 m 3/h biogas (63% CH 4), equivalent to 269 kW (higher heating value, HHV), the SOFC stack was calculated to deliver 131 kW el electricity (48.7%) using a steam-to-carbon ratio of 0.5. This would allow the sewage site to more than cover its own electrical needs, hence to depollute the waste stream at negative energy cost. In its current exploitation using a low efficient gas engine (130 kW), the site is only ?50% self-sufficient. Special attention was given to the thermal balance of the stack. The stack developed heat (143 kW) could be balanced by endothermal reforming (78 kW) and by cathode excess air ? (=3), allowing a temperature difference between stack inlet and outlet of 200 K. The case was compared to other fuel scenarios. Steam-added biogas behaves basically identically to steam-reformed methane. For partial oxidation of biogas or pure hydrogen feeding, electrical efficiency drops to under 43% while ? needs to be raised to 4.5 to maintain the 200 K thermal gradient over the stack.

Van herle, J.; Maréchal, F.; Leuenberger, S.; Membrez, Y.; Bucheli, O.; Favrat, D.

249

Biogas systems in India: is the technology appropriate  

SciTech Connect

In 1973 the Indian government launched a project to install 50,000 biogas plants in villages by 1978. About 36,000 plants were in operation by 1977. Biogas technology was seen as providing a valuable source of energy and fertilizer, helping to conserve forests and preventing soil erosion, improving India's balance of payments and improving rural sanitation and public health. As it turned out, the rigidly stratified socioeconomic structure of Indian villages prevented the lower classes from benefiting from the new technology and had the unforeseen effect of ultimately widening the gap between rich and poor. This article looks at how this happened, examines the socioeconomic impact of biogas and discusses the technical improvements needed to make existing biogas plants into a truly appropriate technology in the context of Indian village life. (Refs. 35).

Tucker, J.B.

1982-10-01

250

Production of Biogas from Wastewaters of Food Processing Industries  

E-print Network

An Upflow Anaerobic Sludge Blanket Process used in converting biodegradable, soluble, organic pollutants in industrial wastewaters to a directly-burnable biogas composed mainly of methane has been developed, tested, and commercially applied...

Sax, R. I.; Holtz, M.; Pette, K. C.

1980-01-01

251

Global warming mitigation potential of biogas plants in India.  

PubMed

Biogas technology, besides supplying energy and manure, provides an excellent opportunity for mitigation of greenhouse gas (GHG) emission and reducing global warming through substituting firewood for cooking, kerosene for lighting and cooking and chemical fertilizers. A study was undertaken to calculate (1) global warming mitigation potential (GMP) and thereby earning carbon credit of a family size biogas plant in India, (2) GMP of the existing and target biogas plants in the country and (3) atmospheric pollution reduction by a family size biogas plant. The GMP of a family size biogas plant was 9.7 t CO(2) equiv. year( - 1) and with the current price of US $10 t( - 1) CO(2) equiv., carbon credit of US $97 year( - 1) could be earned from such reduction in greenhouse gas emission under the clean development mechanism (CDM). A family size biogas plant substitutes 316 L of kerosene, 5,535 kg firewood and 4,400 kg cattle dung cake as fuels which will reduce emissions of NOx, SO(2), CO and volatile organic compounds to the atmosphere by 16.4, 11.3, 987.0 and 69.7 kg year( - 1), respectively. Presently 3.83 million biogas plants are operating in the country, which can mitigate global warming by 37 Mt CO(2) equiv. year( - 1). Government of India has a target of installing 12.34 million biogas plants by 2010. This target has a GMP of 120 Mt CO(2) equiv. year( - 1) and US $1,197 million as carbon credit under the CDM. However, if all the collectible cattle dung (225 Mt) produced in the country is used, 51.2 million family size biogas plants can be supported which will have a GMP of 496 Mt of CO(2) equiv. year( - 1) and can earn US $4,968 million as carbon credit. The reduction in global warming should encourage policy makers to promote biogas technology to combat climate change and integration of carbon revenues will help the farmers to develop biogas as a profitable activity. PMID:18843544

Pathak, H; Jain, N; Bhatia, A; Mohanty, S; Gupta, Navindu

2009-10-01

252

Reactor instrumentation and control design and performance simulation for SP100  

Microsoft Academic Search

The SP-100 flight system will be launched with all primary and secondary lithium in the solid state. Once in orbit, the reactor will be brought critical and maintained at a low power level while the lithium is thawed out. Once the system is thawed out, the reactor power will be controlled to provide the energy source required by the power

R. A. Meyer; A. D. Alley; F. J. Halfen; G. V. Brynsvold

1987-01-01

253

Effect of aeration on the performance of a simulated landfilling reactor stabilizing municipal solid wastes.  

PubMed

In this study, the effects of intermittent aeration on the anaerobic treatment of domestic solid waste and leachate characteristics were investigated in three simulated landfill anaerobic bioreactors. All of the reactors were operated with leachate recirculation and recirculation rate was 300 mL/d. All the reactors were loaded with solid waste having different operational mode. The first reactor was operated with recirculation (control-no aeration). The second reactor was aerated three days in a week during 1 h (Run 1) and the last reactor was aerated one day in a week during 1 h (Run 2). pH, chemical oxygen demand (COD), volatile fatty acids (VFA), ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N) concentrations, total, and methane gas productions in the leachate samples were regularly monitored. 96, 85, and 97% COD and 86, 77, and 93% VFA removals were obtained, in the leachate samples of the control, R1 and R2 reactors, respectively, after 79 days of anaerobic incubation. The TN, TP and NH4-N concentrations in MSW reduced to 4300, 1100, and 160 mg/g from 11,100, 2450, and 630 mg/g in R1 reactor by day 79. The values of pH were 6.98, 6.76, and 7.98, respectively, after anaerobic incubation, respectively in the aforementioned reactors. It was observed that the aeration decreased the methane percentage and the quantity in the simulated bioreactor. The maximum cumulative methane gas production was recorded as 11.2, 0.9, and 3.6 L in control, R1 and R2 reactors, respectively, at the end of 79 days. A BOD5/COD ratio of 0.23 achieved in the R2 reactor indicated the better MSW stabilization resulting in a high rate than that of R1 and control reactors. It was observed that the aerated reactor one day in a week during one hour (R2) reduced the COD and VFA concentrations in leachate samples. The aerated reactor three days in a week during 1 h (R1) reduced the waste quantity, the organic content of the solid waste. The final leachate quantities of aerated runs were lower than that of control reactor operated under strictly anaerobic conditions. PMID:15533016

A?da?, Osman Nuri; Sponza, Delia Teresa

2004-01-01

254

Evaluating livestock manures for biogas production: a GIS based method  

Microsoft Academic Search

The Animals (data)Base for Energy Potential Estimation (ABEPE), presented in this paper, is a GIS based biomass resource assessment application using a relational database management system to estimate biogas production from livestock manures. Energy and biogas potential of livestock residues of all major groups of stock-raising animals (cattle, pigs, sheep\\/goats, poultry, etc.) were evaluated. The calculations were based on geographical

F. A. Batzias; D. K. Sidiras; E. K. Spyrou

2005-01-01

255

Prediction of moving bed biofilm reactor (MBBR) performance for the treatment of aniline using artificial neural networks (ANN).  

PubMed

In this study, the results of 1-year efficiency forecasting using artificial neural networks (ANN) models of a moving bed biofilm reactor (MBBR) for a toxic and hard biodegradable aniline removal were investigated. The reactor was operated in an aerobic batch and continuous condition with 50% by volume which was filled with light expanded clay aggregate (LECA) as carrier. Efficiency evaluation of the reactors was obtained at different retention time (RT) of 8, 24, 48 and 72 h with an influent COD from 100 to 4000 mg/L. Exploratory data analysis was used to detect relationships between the data and dependent evaluated one. The appropriate architecture of the neural network models was determined using several steps of training and testing of the models. The ANN-based models were found to provide an efficient and a robust tool in predicting MBBR performance for treating aromatic amine compounds. PMID:20399558

Delnavaz, M; Ayati, B; Ganjidoust, H

2010-07-15

256

Effect of phenol on the nitrogen removal performance and microbial community structure and composition of an anammox reactor.  

PubMed

The effects of phenol on the nitrogen removal performance of a sequencing batch reactor (SBR) with anammox activity and on the microbial community within the reactor were evaluated. A phenol concentration of 300 mg L(-1) reduced the ammonium-nitrogen removal efficiency of the SBR from 96.5% to 47%. The addition of phenol changed the microbial community structure and composition considerably, as shown by denaturing gradient gel electrophoresis and 454 pyrosequencing of 16S rRNA genes. Some phyla, such as Proteobacteria, Verrucomicrobia, and Firmicutes, increased in abundance, whereas others, such as Acidobacteria, Chloroflexi, Planctomycetes, GN04, WS3, and NKB19, decreased. The diversity of the anammox bacteria was also affected by phenol: sequences related to Candidatus Brocadia fulgida were no longer detected, whereas sequences related to Ca. Brocadia sp. 40 and Ca. Jettenia asiatica persisted. These results indicate that phenol adversely affects anammox metabolism and changes the bacterial community within the anammox reactor. PMID:24907569

Pereira, Alyne Duarte; Leal, Cíntia Dutra; Dias, Marcela França; Etchebehere, Claudia; Chernicharo, Carlos Augusto L; de Araújo, Juliana Calabria

2014-08-01

257

Effects of hexavalent chromium on performance and microbial community of an aerobic granular sequencing batch reactor.  

PubMed

The performance and microbial community of an aerobic granular sequencing batch reactor (GSBR) were investigated at different hexavalent chromium (Cr(VI)) concentrations. The COD and NH4 (+)-N removal efficiencies decreased with the increase in Cr(VI) concentration from 0 to 30 mg/L. The specific oxygen utilization rate (SOUR) decreased from 34.86 to 12.18 mg/(g mixed liquor suspended sludge (MLSS)·h) with the increase in Cr(VI) concentration from 0 to 30 mg/L. The specific ammonium oxidation rate (SAOR), specific nitrite oxidation rate (SNOR), and specific nitrate reduction rate (SNRR) decreased with the increase in Cr(VI) concentration, whereas the SNRR was always higher than the sum of SAOR and SNOR at 0-30 mg/L Cr(VI). The scanning electron micrographs (SEM) showed some undefined particles on the surface of filamentous bacteria that might be the chelation of chromium and macromolecular organics at 30 mg/L Cr(VI). The denaturing gradient gel electrophoresis (DGGE) profiles revealed that some microorganisms adapting to high Cr(VI) concentration gradually became the predominant bacteria, while others without Cr(VI)-tolerance capacity tended to deplete or weaken. Some bacteria could tolerate the toxicity of high Cr(VI) concentration in the aerobic GSBR, such as Propionibacteriaceae bacterium, Ochrobactrum anthropi, and Micropruina glycogenica. PMID:25318421

Wang, Zichao; Gao, Mengchun; She, Zonglian; Jin, Chunji; Zhao, Yangguo; Yang, Shiying; Guo, Liang; Wang, Sen

2014-10-17

258

Electron versus proton accelerator driven sub-critical system performance using TRIGA reactors at power  

SciTech Connect

This paper provides a comparison of the performance of an electron accelerator-driven experiment, under discussion within the Reactor Accelerator Coupling Experiments (RACE) Project, being conducted within the U.S. Dept. of Energy's Advanced Fuel Cycle Initiative (AFCI), and of the proton-driven experiment TRADE (TRIGA Accelerator Driven Experiment) originally planned at ENEA-Casaccia in Italy. Both experiments foresee the coupling to sub-critical TRIGA core configurations, and are aimed to investigate the relevant kinetic and dynamic accelerator-driven systems (ADS) core behavior characteristics in the presence of thermal reactivity feedback effects. TRADE was based on the coupling of an upgraded proton cyclotron, producing neutrons via spallation reactions on a tantalum (Ta) target, with the core driven at a maximum power around 200 kW. RACE is based on the coupling of an Electron Linac accelerator, producing neutrons via photoneutron reactions on a tungsten-copper (W-Cu) or uranium (U) target, with the core driven at a maximum power around 50 kW. The paper is focused on analysis of expected dynamic power response of the RACE core following reactivity and/or source transients. TRADE and RACE target-core power coupling coefficients are compared and discussed. (authors)

Carta, M.; Burgio, N.; D'Angelo, A.; Santagata, A. [ENEA, C.R. Casaccia, via Anguillarese, 301, 00060, S. Maria di Galeria, Rome (Italy); Petrovich, C. [ENEA, C.R.E. Clementel, via M. M. Sole, 4, 40129, Bologna (Italy); Schikorr, M. [Forschungszentrum Karlsruhe FZK, Postfach 3640, D-76021 Karlsruhe (Germany); Beller, D. [Univ. of Nevada, 4505 Maryland Parkway, Las Vegas, NV 89154-4027 (United States); Felice, L. S. [CEA, CEN Cadarache, 13108 St-Paul-lez-Durance (France); Imel, G. [Argonne National Laboratory, 9700 South Cass Ave, Argonne, IL 60439 (United States); Salvatores, M. [Forschungszentrum Karlsruhe FZK, Postfach 3640, D-76021 Karlsruhe (Germany); CEA, CEN Cadarache, 13108 St-Paul-lez-Durance (France)

2006-07-01

259

Linking performance with microbial community characteristics in an anaerobic baffled reactor.  

PubMed

The performance and microbial community characteristics of a laboratory scale anaerobic baffled reactor (ABR) with four compartments (C1-C4) treating sugar refinery wastewater were investigated. The COD removal was 94.8 % with a CH4 yield of 0.21 L?g(-1) CODremoved at total organic loading rate (OLR) of 5.33 kg COD/m(-3)?day(-1). Fermentative bacteria were dominant in C1 and C2, while syntrophic acetogens and methanogens were dominant in C3 and C4. Some acid-tolerant methanogens were enriched in acidogenic phase. The present of the acid-tolerant methanogens could improve the efficiency and stability of the ABR as the most of the methanogens are vulnerable to low pH. In addition, high functional redundancy of the fermentative bacteria implicated that the microbial communities in acidogenic phase were stable functionally and allowed the ABR to balance perturbation. It was also found that syntrophic acetogenesis might be a weakness in the ABR as syntrophic acetogens were poor as compared with fermentative bacteria and methanogens. PMID:23344944

Ban, Qiaoying; Li, Jianzheng; Zhang, Liguo; Jha, Ajay Kumar; Nies, Loring

2013-03-01

260

Alloy development for irradiation performance in fusion reactors. Annual report, September 1979-September 1980  

SciTech Connect

This report summarizes the research and development work performed during the second year of an M.I.T. project directed toward the development of improved structural alloys for the fusion reactor first wall application. Several new alloys have been produced by rapid solidification. Emphasis in alloy design and production has been placed on producing austenitic Type 316SS with fine dispersions of TiC and Al/sub 2/O/sub 3/ particles. Results of mechanical and microstructural tests are presented. A number of neutron irradiations have been initiated on samples fabricated from alloys produced in this project. A dual beam, heavy ion and helium ion, irradiation was completed using several alloys and a range of temperatures, damage rates and total doses. Modeling of irradiation phenomena has been continued with emphasis in the last year upon understanding the effect of recoil resolution on relatively stable second phase particles. Work continued to fully characterize the microstructure of several ZrB/sub 2/ doped stainless steels.

Harling, O.K.; Grant, N.J.

1980-12-01

261

Explosion characteristics of synthesised biogas at various temperatures.  

PubMed

Biogas is considered as a valuable source of renewable energy. Indeed, it can be turned into useful energy (heat, electricity, fuel) and can contribute to reduce greenhouse gas emissions. Knowledge of its safety characteristics is a very important practical issue. Experimental investigation of synthesised biogas explosion characteristics was conducted in a 20-L sphere at various temperatures (30-70 degrees C) and at atmospheric pressure. The studied biogas was made of 50% methane (CH(4)) and 50% carbon dioxide (CO(2)). It was also saturated with humidity: this composition is frequently met in digesters during waste methanisation. There are two inert gases in biogas: water vapour and carbon dioxide. Its vapour water content rises along with temperature. The presence of these inert gases modifies considerably biogas characteristics compared to the ones of pure methane: explosion limits are lowered and beyond 70 degrees C, water vapour content is sufficient to inert the mixture. Furthermore, explosion violence (estimated with the maximum rate of pressure rise values, (dp/dt)(max)) is three times lower for biogas than for pure methane at ambient temperature. PMID:16466853

Dupont, L; Accorsi, A

2006-08-25

262

Biogas generation from in-storage psychrophilic anaerobic digestion.  

PubMed

In-storage psychrophilic anaerobic digestion (ISPAD) is a technology allowing livestock producers to operate an anaerobic digester with minimum technological know-how and for the cost of a conventional storage cover. Nevertheless, the system is exposed to ambient temperatures and biogas production is expected to vary with climatic conditions. The objective of the project was therefore to measure ISPAD biogas production during the winter and fall seasons for a region east of Montreal, Canada. A calibrated biogas monitoring system was used to monitor biogas methane and carbon dioxide concentrations inside a two-year-old field installation with a 1000 m3 storage capacity. Despite a leaking pumping hatch, winter 2010 (January to March) methane concentrations varied directly with solar radiation and maximum exterior temperature, rather than with manure temperature at 2.4 and 1.2 m depths which remained relatively constant between 1 and 5 degrees C. During a six-month-period from November 2009 to April 2010, inclusively, the field ISPAD degraded 34% of the manure volatile solids corresponding to an average methane production of 40 m3/d. The ISPAD biogas production could be further increased by improving its air tightness and intrusion and by regularly pumping out the biogas. PMID:23837352

Giard, David; Choiniere, Denis; Cordeau, Sébastien; Barrington, Suzelle

2013-01-01

263

The potential of oxygen to improve the stability of anaerobic reactors during unbalanced conditions: results from a pilot-scale digester treating sewage sludge.  

PubMed

A well-functioning pilot reactor treating sewage sludge at approximately 4.4 NL/m(3)/d of oxygen supply and 18d of hydraulic retention time (HRT) was subjected to a hydraulic overload to investigate whether oxygen benefits successful operation in stressful circumstances. Only a mild imbalance was caused, which was overcome without deterioration in the digestion performance. Volatile solids (VS) removal was 45% and 43% at 18 and 14 d of HRT, respectively. Biogas productivity remained around 546 NmL/gVS, but it was slightly higher during the period of imbalance. Thereafter, similar performances were achieved. Under anaerobic conditions, VS removal and biogas productivity were respectively 41% and 525 NmL/gVS, hydrogen partial pressure rose, and acetic acid formation became less favourable. Oxygen seemed to form a more stable digestion system, which meant increased ability to deal successfully with overloads. Additionally, it improved the biogas quality; methane concentration was negligibly lower, while hydrogen sulphide and oxygen remained around 0.02 and 0.03%v/v, respectively. PMID:23672942

Ramos, I; Fdz-Polanco, M

2013-07-01

264

Method and apparatus for enhancing reactor air-cooling system performance  

DOEpatents

An enhanced decay heat removal system for removing heat from the inert gas-filled gap space between the reactor vessel and the containment vessel of a liquid metal-cooled nuclear reactor. Multiple cooling ducts in flow communication with the inert gas-filled gap space are incorporated to provide multiple flow paths for the inert gas to circulate to heat exchangers which remove heat from the inert gas, thereby introducing natural convection flows in the inert gas. The inert gas in turn absorbs heat directly from the reactor vessel by natural convection heat transfer.

Hunsbedt, Anstein (Los Gatos, CA)

1996-01-01

265

Method and apparatus for enhancing reactor air-cooling system performance  

DOEpatents

An enhanced decay heat removal system is disclosed for removing heat from the inert gas-filled gap space between the reactor vessel and the containment vessel of a liquid metal-cooled nuclear reactor. Multiple cooling ducts in flow communication with the inert gas-filled gap space are incorporated to provide multiple flow paths for the inert gas to circulate to heat exchangers which remove heat from the inert gas, thereby introducing natural convection flows in the inert gas. The inert gas in turn absorbs heat directly from the reactor vessel by natural convection heat transfer. 6 figs.

Hunsbedt, A.

1996-03-12

266

Performances and microbial features of an aerobic packed-bed biofilm reactor developed to post-treat an olive mill effluent from an anaerobic GAC reactor  

PubMed Central

Background Olive mill wastewater (OMW) is the aqueous effluent of olive oil producing processes. Given its high COD and content of phenols, it has to be decontaminated before being discharged. Anaerobic digestion is one of the most promising treatment process for such an effluent, as it combines high decontamination efficiency with methane production. The large scale anaerobic digestion of OMWs is normally conducted in dispersed-growth reactors, where however are generally achieved unsatisfactory COD removal and methane production yields. The possibility of intensifying the performance of the process using a packed bed biofilm reactor, as anaerobic treatment alternative, was demonstrated. Even in this case, however, a post-treatment step is required to further reduce the COD. In this work, a biological post-treatment, consisting of an aerobic biological "Manville" silica bead-packed bed aerobic reactor, was developed, tested for its ability to complete COD removal from the anaerobic digestion effluents, and characterized biologically through molecular tools. Results The aerobic post-treatment was assessed through a 2 month-continuous feeding with the digested effluent at 50.42 and 2.04 gl-1day-1 of COD and phenol loading rates, respectively. It was found to be a stable process, able to remove 24 and 39% of such organic loads, respectively, and to account for 1/4 of the overall decontamination efficiency displayed by the anaerobic-aerobic integrated system when fed with an amended OMW at 31.74 and 1.70 gl-1day-1 of COD and phenol loading rates, respectively. Analysis of 16S rRNA gene sequences of biomass samples from the aerobic reactor biofilm revealed that it was colonized by Rhodobacterales, Bacteroidales, Pseudomonadales, Enterobacteriales, Rhodocyclales and genera incertae sedis TM7. Some taxons occurring in the influent were not detected in the biofilm, whereas others, such as Paracoccus, Pseudomonas, Acinetobacter and Enterobacter, enriched significantly in the biofilter throughout the treatment. Conclusion The silica-bead packed bed biofilm reactor developed and characterized in this study was able to significantly decontaminate anaerobically digested OMWs. Therefore, the application of an integrated anaerobic-aerobic process resulted in an improved system for valorization and decontamination of OMWs. PMID:16595023

Bertin, Lorenzo; Colao, Maria Chiara; Ruzzi, Maurizio; Marchetti, Leonardo; Fava, Fabio

2006-01-01

267

Anaerobic filter reactor performance for the treatment of complex dairy wastewater at industrial scale.  

PubMed

The wastewaters discharged by raw milk quality control laboratories are more complex than the ones commonly generated by dairy factories because of the presence of certain chemicals such as sodium azide or chloramphenicol, which are used for preserving milk before analysis. The treatment of these effluents has been carried out in a full-scale plant comprising a 12 m(3) anaerobic filter (AF) reactor and a 28 m(3) sequential batch reactor (SBR). After more than 2 years of operation, a successful anaerobic treatment of these effluents was achieved, without fat removal prior to the anaerobic reactor. The organic loading rates maintained in the AF reactor were 5-6 kg COD/m(3) d, with COD removal being higher than 90%. No biomass washout was observed, and most of the fat contained in the wastewaters was successfully degraded. The addition of alkalinity is crucial for the maintenance of a proper buffer medium to ensure pH stability. The effluent of the AF reactor was successfully treated in the SBR reactor, and a final effluent with a COD content below 200 mg/l and total nitrogen below 10mg N/l was obtained. PMID:12946891

Omil, Francisco; Garrido, Juan M; Arrojo, Belén; Méndez, Ramón

2003-10-01

268

Treatment of spent wash in anaerobic thermophilic suspended growth reactor (ATSGR).  

PubMed

Pollution through spent wash is a major problem in India. There is an urgent need to develop wastewater treatment technologies for safer disposal. In the present investigation, an attempt has been made to examine a few aspects of thermophilic anaerobic digestion of spent wash collected from a distillery. The study was carried out in a 4 liter laboratory scale anaerobic thermophilic suspended growth reactor After the successful startup, the organic loading was increased stepwise to assess the performance of the reactor. During the study period, biogas generated was recorded and the maximum gas generated was found to be 11.9 liter at an organic loading rate (OLR) of 29 g COD/l. A 500% increase in the volatile fatty acid (VFA) concentration (1850 mg/l) was observed, when the OLR was increased from 29 to 30 g COD/l. During the souring phase the removal of COD, total solids (TS) and volatile solids (VS) were in the order of 52%, 40% and 46% respectively The methane content in the biogas varied from 65% to 75%. PMID:17929774

Banu, Rajesh; Kaliappan, S; Beck, Dieter

2007-04-01

269

Treatment of spent wash in anaerobic mesophilic suspended growth reactor (AMSGR).  

PubMed

Approximately 400 KL of spent wash or vinasse per annum is generated at an average COD concentration of 100,000 mg/l, by over 250 distilleries in India. There is an urgent need to develop, assess and use ecofriendly methods for the disposal of this high strength wastewater. Therefore, an attempt was made to investigate a few aspects of anaerobic digestion of spent wash collected from a distillery. The study was carried out in a 4 L laboratory scale anaerobic mesophilic suspended growth reactor. After the successful startup, the organic loading was increased stepwise to assess the performance of the reactor. During the study period, biogas generated was recorded and the maximum gas generated was found to be 16.9 L at an Organic Loading Rate (OLR) of 38 g COD/L. A 500% increase in the Volatile Fatty Acid (VFA) concentration (2150 mg/L) was observed, when the OLR was increased from 38 to 39 g COD/L. During the souring phase the removal of COD, Total Solids (TS) and Volatile Solids (VS) were in the order of 52%, 40% and 46% respectively. The methane content in the biogas varied from 65% to 75%. PMID:16850887

Banu, J Rajesh; Kaliappan, S; Rajkumar, M; Beck, Dieter

2006-01-01

270

Performance of uasb reactor treating leachate from acidogenic fermenter in the two-phase anaerobic digestion of food waste  

Microsoft Academic Search

This study was conducted to investigate the performance of the upflow anaerobic sludge blanket (UASB) reactor treating leachate from acidogenic fermenter in the two-phase anaerobic digestion of food waste. The chemical oxygen demand (COD) removal efficiency was consistently over 96% up to the loading rates of 15.8gCOD\\/ld. The methane production rate increased to 5.5l\\/ld. Of all the COD removed, 92%

H. S Shin; S. K Han; Y. C Song; C. Y Lee

2001-01-01

271

The impact of ENDF\\/BV fission spectrum parameter uncertainty on the prediction of fast reactor burnup performance  

Microsoft Academic Search

The sensitivity and uncertainty of various core burnup performance quantities (e.g., k[sub eff], burnup reactivity swing, local power density, etc.) to the heavy isotope fission spectrum parameters was investigated using depletion perturbation methods and ENDF\\/B-V covariance data. A brief description of the methods is followed by results of a 900-MW(thermal) fast reactor. The analysis here indicates that for a 900-MW(thermal)

T. J. Downar; J. Broda; J. Kritzer

1990-01-01

272

Biodegradation of distillery spent wash in anaerobic hybrid reactor.  

PubMed

A lab-scale anaerobic hybrid (combining sludge blanket and filter) reactor was operated in a continuous mode to study anaerobic biodegradation of distillery-spent wash. The study demonstrated that at optimum hydraulic retention time (HRT), 5 days and organic loading rate (OLR), 8.7kgCOD/m(3)d, the COD removal efficiency of the reactor was 79%. The anaerobic reduction of sulfate increases sulfide concentration, which inhibited the metabolism of methanogens and reduced the performance of the reactors. The kinetics of biomass growth i.e. yield coefficient (Y,0.0532) and decay coefficient (K(d), 0.0041d(-1)) was obtained using Lawrence and McCarty model. However, this model failed in determining the kinetics of substrate utilization. Bhatia et al. model having inbuilt provision of process inhibition described the kinetics of substrate utilization, i.e. maximum rate of substrate utilization (R,1.945d(-1)) and inhibition coefficient values (K(i),0.032L/mg). Modeling of the reactor demonstrated that Parkin and Speece, and Bhatia et al. models, both, could be used to predict the effluent substrate concentration. However, Parkin and Speece model predicts effluent COD more precisely (within +/-2%) than Bhatia et al. model (within +/-5-20%) of the experimental value. Karhadkar et al. model predicted biogas yield within +/-5% of the experimental value. PMID:17229451

Sunil Kumar, Gupta; Gupta, S K; Singh, Gurdeep

2007-02-01

273

Biogas production improvement and C/N control by natural clinoptilolite addition into anaerobic co-digestion of Phragmites australis, feces and kitchen waste.  

PubMed

Anaerobic co-digestion (A co-D) performance of Phragmites australis, feces and kitchen waste with addition of clinoptilolite (one main kind of zeolite) was investigated to evaluate the improvement of biogas/methane production and internal mechanism of nitrogen and organics control. A better biogas/methane production was observed by 10% clinoptilolite (v/v) than bentonite and diatomite, with the shortest lag phase of 0.070d(-1), the max rate of 15.89L/(kgVSday) and ultimate biogas production of 308.2L/kgVS as the modified Gompertz equation predicted. Accordingly, the content of methane in the biogas was increased from 44.10% to 65.30%. Furthermore, the clinoptilolite inhibited the acidification of digestion liquid (optimum pH 7.0-7.5) and enhanced the VFAs (acetic acid, propionic acid and butyric acid) destruction. Moreover, 10% of clinoptilolite optimally enhanced the microbial utilization of Ca(2+)/Mg(2+), controlled the C/N ratio, and improved the biogas production as well as NH3-N/NO3-N inhibition efficiency. PMID:25603527

Wang, Xiaowei; Zhang, Lieyu; Xi, Beidou; Sun, Wenjun; Xia, Xunfeng; Zhu, Chaowei; He, Xiaosong; Li, Mingxiao; Yang, Tianxue; Wang, Pengfei; Zhang, Zhonglei

2015-03-01

274

Changes in the Archaea microbial community when the biogas fermenters are fed with protein-rich substrates.  

PubMed

Terminal restriction fragment length polymorphism (T-RFLP) was applied to study the changes in the composition of the methanogens of biogas-producing microbial communities on adaptation to protein-rich monosubstrates such as casein and blood. Specially developed laboratory scale (5-L) continuously stirred tank reactors have been developed and used in these experiments. Sequencing of the appropriate T-RF fragments selected from a methanogen-specific (mcrA gene-based) library revealed that the methanogens responded to the unconventional substrates by changing the community structure. T-RFLP of the 16S rDNA gene confirmed the findings. PMID:23340109

Ács, Norbert; Kovács, Etelka; Wirth, Roland; Bagi, Zoltán; Strang, Orsolya; Herbel, Zsófia; Rákhely, Gábor; Kovács, Kornél L

2013-03-01

275

Neutronic performance of the WWR-M research reactor in Ukraine.  

SciTech Connect

The 10 MW, WWR-M research reactor of the Kiev Institute for Nuclear Research is jointly studied with the Argonne National Laboratory to examine the feasibility of conversion from HEU (36%) to LEU (19.75%) fuel. A potential core configuration was chosen for comparison of analytical results with HEU fuel and candidate replacement LEU fuels. Core reactivity, fuel assembly power, experiment flux, fuel-cycle length, the number of fuel assemblies consumed per year, and shutdown margins are compared using HEU and LEU fuels. The reactor currently uses HEU (36%) WWR-M2 fuel assemblies (3 tubes, UO2-Al fuel meat with 1.1 gU/cm3 and 37.0 g {sup 235}U). Candidate LEU replacement fuel assemblies, which would result in the same fuel cycle length and the same annual fuel consumption as the HEU (36%) fuel are: LEU WWR-M2 (3 tubes, UO2-Al fuel meat with 2.3 gU/cm3 and 38.3 g 235U) and LEU WWR-MR (37 pins, U9Mo-Al fuel meat with 2.4 gU/cm3 and 38.1 g {sup 235}U). Five LEU WWR-M2 fuel assemblies with 41.7 g {sup 235}U per assembly, UO{sub 2}-Al fuel meat with 2.5 gU/cm3, and a fueled height of 50 cm have completed irradiation testing in the WWR-M reactor at the Petersburg Nuclear Physics Institute in Gatchina to an average 235U burnup of over 70%. This LEU fuel is considered to be qualified for conversion of the WWR-M reactor in Kiev and other research reactors using HEU (36%) WWR-M2 fuel assemblies. For reactors using assemblies with a fueled height of 60 cm, the 235U content per assembly would be 50 g with the same fuel meat composition as the fuel assemblies that were tested in Gatchina. Two 37-pin LEU test assemblies - one with UO{sub 2}-Al fuel meat and about 48 g {sup 235}U and the other with U9Mo-Al fuel meat and about 96 g {sup 235}U are scheduled to begin irradiation testing in the WWR-M reactor in Gatchina before the end of 2002. If these tests (lasting about two years) are successful, LEU pin-type fuel assemblies with up to 96 g 235U would be candidate fuels for LEU conversion of the WWR-M reactor in Kiev and other research reactors using WWR-M2 fuel assemblies.

Pond, R. B.; Hanan, N. A.; Matos, J. E.; Mahlers, Y.; Dyakov, A.; Technology Development; Kiev Inst. for Nuclear Research

2002-01-01

276

Analysis of the Performance of a Flow Reactor for Use with Microcolumn HPLC  

PubMed Central

Postcolumn derivatization reactions can be used to improve detector sensitivity or selectivity. The advantages of capillary chromatography for trace analysis could be augmented if there were postcolumn reactors suitable for microchromatographic systems. However, postcolumn derivatization is a challenge because of the small peak volumes associated with capillary columns. We have developed a postcolumn flow reactor from microchannels formed in fluorinated ethylene propylene and 50-?m fused-silica tubing for use with capillary HPLC analyses. Theoretical and experimental evidence show that the reactor, which operates in the Taylor dispersion regime, enables contact of analyte and derivatization streams purely by diffusion. Reactor lengths as short as 2 cm allow formation of copper(II)–peptide complexes that are detected electrochemically at a carbon fiber microelectrode. The reactor has been used with 100-?m-i.d. columns with insignificant effects (i.e., <3%) on peak band spreading. Theoretical calculations indicate that even smaller i.d. columns can be used with little effect on chromatographic resolution. PMID:14750858

Beisler, Amy T.; Sahlin, Eskil; Schaefer, Kathleen E.; Weber, Stephen G.

2006-01-01

277

Response of aerobic granular sludge to the long-term presence to nanosilver in sequencing batch reactors: Reactor performance, sludge property, microbial activity and community.  

PubMed

The increasing use of silver nanoparticles (Ag NPs) raises concerns about their potential toxic effects on the environment. Granular shape sludge is a special type of microbial aggregate. The response of aerobic granular sludge (AGS) to the long-term presence of Ag NPs has not been well studied. In this study, AGS was exposed to 5 and 50mg/L Ag NPs in sequence batch reactors (SBRs) for 69days, and its response was evaluated based on the sludge properties, microbial activity and community, and reactor performance. The results showed that Ag NPs caused inhibition to microbial activities of AGS from Day 35. At the end of 69days of Ag NPs exposure, the microbial activity of AGS was significantly inhibited in terms of inhibitions of the ammonia oxidizing rate (33.0%), respiration rate (17.7% and 45.6%) and denitrification rate (6.8%), as well as decreases in the ammonia mono-oxygenase and nitrate reductase activities. During the long-term exposure, the AGS maintained its granular shape and large granule size (approximately 900?m); the microbial community of AGS slightly changed, but the dominant microbial population remained. Overall, the AGS tolerated the toxicity of Ag NPs well, but a long-term exposure may produce chronic toxicity to the AGS, which is concerning. PMID:25460955

Quan, Xiangchun; Cen, Yan; Lu, Fang; Gu, Lingyun; Ma, Jingyun

2015-02-15

278

Energy balance model of a SOFC cogenerator operated with biogas  

NASA Astrophysics Data System (ADS)

A small cogeneration system based on a Solid Oxide Fuel Cell (SOFC) fed on the renewable energy source biogas is presented. An existing farm biogas production site (35 m 3 per day), currently equipped with a SOFC demonstration stack, is taken for reference. A process flow diagram was defined in a software package allowing to vary system operating parameters like the fuel inlet composition, reforming technology, stack temperature and stack current (or fuel conversion). For system reforming simplicity, a base case parameter set was defined as the fuel inlet of 60% CH 4:40% CO 2 mixed with air in a 1:1 ratio, together with 800 °C operating temperature and 80% fuel conversion. A model stack, consisting of 100 series elements of anode supported electrolyte cells of 100 cm 2 each, was calculated to deliver 3.1 kW el and 5.16 kW th from an input of 1.5 N m 3/h of biogas (8.95 kW LHV), corresponding to 33.8 and 57.6% electrical and thermal efficiencies (Lower Heating Values (LHVs)), respectively. The incidence on the efficiencies of the model system was examined by the variation of a number of parameters such as the CO 2 content in the biogas, the amount of air addition to the biogas stream, the addition of steam to the fuel inlet, the air excess ratio ? and the stack operating temperature, and the results discussed.

Van herle, Jan; Maréchal, F.; Leuenberger, S.; Favrat, D.

279

Biogas end-use in the European community  

SciTech Connect

In Europe over the past few years the generation of biogas for energy and environmental purposes has been gaining in importance. Industrial wastewaters, cattle manure, sewage sludges, urban wastes, crop residues, algae and aquatic biomass are all typical of the materials being utilized. In contrast to the extensive inventory of biomethanation processes which has been carried out within the EEC, until recently a detailed, up-to-date investigation of the end-sues of biogas had not been undertaken. To supply the necessary information, the Commission of the European Communities and the Belgian Science Policy Office jointly entrusted a study to the Unit of Bioengineering at the Catholic University of Louvain, Belgium. This book is record of the study and has the following key features: it gives a broad overview of the ongoing use of biogas in Europe; it summarizes available data on storage, purification and engines using biogas; it draws several conclusions concerning the technical and economic viability of the processes; it discusses the problems of using biogas; and it outlines recommendations and future R and D and demonstration projects in the field.

Constant, M.; Naveau, H.; Nyns, E.J. (Unite de Genie Biologique, Universite Catholique de Louvain (BE)); Ferrero, G.L.

1989-01-01

280

Application of polyimide membranes for biogas purification and enrichment.  

PubMed

Biogas is a clean environment friendly fuel that is produced by bacterial conversion of organic matter under anaerobic (oxygen-free) conditions. Raw biogas contains about 55-65% methane (CH(4)), 30-45% carbon dioxide (CO(2)), traces of hydrogen sulphide (H(2)S) and fractions of water vapour. Pure methane has a calorific value of 9100 kcal/m(3) at 15.5 degrees C and 1 atm; the calorific value of biogas varies from 4800 to 6900 kcal/m(3). To achieve the standard composition of the biogas and calorific value of 5500 kcal/m(3) the treatment techniques like absorption or membrane separation should be applied. In the paper the results of the tests of the CH(4) enrichment in simulated biogas mixture consisted of methane, carbon dioxide and hydrogen sulphide were presented. It was showed that using the capillary module with polyimide membranes it was possible to achieve the enrichment of CH(4) from the concentrations of 55-85% up to 91-94.4%. The membrane material was resistant to the small concentrations of sour gases and assured the reduction of H(2)S and water vapour concentrations, as well. The required enrichment was achieved in the single module, however to prevent CH(4) losses the multistage or hybrid systems should be used to improve process efficiency. PMID:17324508

Harasimowicz, M; Orluk, P; Zakrzewska-Trznadel, G; Chmielewski, A G

2007-06-18

281

Near-term tokamak-reactor designs with high-performance resistive magnets  

SciTech Connect

Advanced Fusion Test Reactors (AFTR) designs have been developed using BITTER type magnets which are capable of steady state operation. The goals of compact AFTR designs (with major radii R approx. 2.5 - 4 m), include DT ignition with large physics margins; high duty cycle, long pulse operation; and DD-DT operation with low tritium concentration. Larger AFTR designs (R approx. 5 m), have the additional goal of early demonstration of self sufficiency in tritium production. The AFTR devices could also serve as prototypes for commercial reactors. Compact ignition test reactors have also been designed (R approx. 1 - 2 m). These designs use BITTER magnets that are inertially cooled starting at liquid nitrogen temperature. A detailed engineering design was developed for ZEPHYR.

Cohn, D.R.; Bromberg, L.; Williams, J.E.C.; Becker, H.; Leclaire, R.; Yang, T.

1981-10-01

282

Landfill Biogas for heating Greenhouses and providing Carbon Dioxide Supplement for Plant Growth  

Microsoft Academic Search

Present municipal solid waste landfills generate biogas and leachate. Biogas is flared on site to destroy noxious contaminants and water is extracted from leachate to be drained away. However, biogas could alternatively be a cheap fuel for winter heating and could provide horticultural greenhouses with abundant carbon dioxide to boost plant growth all year long. The paper describes how this

A Jaffrin; N Bentounes; A. M Joan; S Makhlouf

2003-01-01

283

Microalgae as substrates for fermentative biogas production in a combined biorefinery concept  

Microsoft Academic Search

Most organic matter can be used for bioenergy generation via anaerobic fermentation. Today, crop plants like maize play the dominant role as substrates for renewable biogas production. In this work we investigated the suitability of six dominant microalgae species (freshwater and saltwater algae and cyanobacteria) as alternative substrates for biogas production. We could demonstrate that the biogas potential is strongly

J. H. Mussgnug; V. Klassen; A. Schlüter; O. Kruse

2010-01-01

284

The optimal production of biogas for use as a transport fuel in Ireland  

Microsoft Academic Search

The Biofuels Directive places an onus on EU member states to ensure that biofuels are placed on their markets. This paper investigates the use of CH4-enriched biogas as a fuel. A number of options, which produce CH4-enriched biogas, were analysed from technical, economic and environmental perspectives. Biogas may be produced at a centralised anaerobic digestion (CAD) facility, accepting agricultural slurries

J. D. Murphy; K. McCarthy

2005-01-01

285

IEA-Renewable Energy Technologies, Bioenergy Agreement Task 37: Energy from Biogas and Landfill Gas  

E-print Network

EFP-06 IEA- Renewable Energy Technologies, Bioenergy Agreement Task 37: Energy from Biogas-Bioenergy, Task 37- Energy from Biogas and Landfill Gas", via samarbejde, informationsudveksling, fælles analyser. biogas fra anaerob udrådning (AD) som en integreret gylle og affalds behandlings teknologi. Arbejdet

286

A methodology for financial evaluation of biogas technology in India using cost functions  

Microsoft Academic Search

A methodology for financial evaluation of biogas technology for domestic use in India using recently developed cost functions is reported. Analytical expressions for the unit cost of biogas and cost per unit of useful energy delivered by a biogas plant in combination with other suitable technologies have been developed. Net present value and discounted pay-back period have been calculated. The

Seemin Rubab; Tara Chandra Kandpal

1996-01-01

287

Proceedings of Healthy Buildings 2009 Paper 206 Risk assessment of biogas exposure in kitchens  

E-print Network

Proceedings of Healthy Buildings 2009 Paper 206 Risk assessment of biogas exposure in kitchens C to pollutants while using biogas for cooking was assessed following the methodology described by the US - National Research Council. Information of hazardous compounds and compositions of several biogas types were

Paris-Sud XI, Université de

288

The Biogas/Biofertilizer Business Handbook. Third Edition. Appropriate Technologies for Development. Reprint R-48.  

ERIC Educational Resources Information Center

This book describes one approach to building and operating biogas systems. The biogas systems include raw material preparation, digesters, separate gas storage tanks, use of the gas to run engines, and the use of the sludge as fertilizer. Chapters included are: (1) "Introduction"; (2) "Biogas Systems are Small Factories"; (3) "The Raw Materials of…

Arnott, Michael

289

Defluoridation of drinking water by electrocoagulation\\/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor  

Microsoft Academic Search

Defluoridation using batch electrocoagulation\\/electroflotation (EC\\/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The

A. H. Essadki; B. Gourich; Ch. Vial; H. Delmas; M. Bennajah

2009-01-01

290

Extension of the TRANSURANUS code to the fuel rod performance analysis of LBE-cooled nuclear reactors  

NASA Astrophysics Data System (ADS)

This work intends to be a starting point for the extension of the TRANSURANUS fuel rod performance code to the modelling of the T91 steel, which is designed to be the cladding material in LBE (lead-bismuth eutectic) accelerator-driven systems (ADS). On the basis of the experimental data available in the recent literature on LBE and T91, a preliminary modelling of the T91 corrosion with flowing LBE under oxygen control is proposed, and the main issues (i.e., heat transfer, creep, swelling) relevant for the performance of this steel in a reactor are discussed, in order to be properly considered in TRANSURANUS.

Botazzoli, P.; Agosti, F.; di Marcello, V.; Luzzi, L.

291

A numerical and experimental analysis of reactor performance and deposition rates for CVD on monofilaments  

NASA Technical Reports Server (NTRS)

The computational fluid dynamics (CFD) code FLUENT is adopted to simulate a cylindrical upflow reactor designed for chemical vapor deposition (CVD) on monofilaments. Equilibrium temperature profiles along the fiber and quartz reactor wall are experimentally measured and used as boundary conditions in numerical simulations. Two-dimensional axisymmetric flow and temperature fields are calculated for hydrogen and argon; the effect of free convection is assessed. The gas and surface chemistry is included for predicting silicon deposition from silane. The model predictions are compared with experimentally measured silicon CVD rates. Inferences are made for optimum conditions to obtain uniformity.

Gokoglu, S. A.; Kuczmarski, M.; Veitch, L.; Tsui, P.; Chait, A.

1990-01-01

292

Gas Sensing of SnO2 Nanocrystals Revisited: Developing Ultra-Sensitive Sensors for Detecting the H2S Leakage of Biogas  

NASA Astrophysics Data System (ADS)

As a typical mode of energy from waste, biogas technology is of great interest to researchers. To detect the trace H2S released from biogas, we herein demonstrate a high-performance sensor based on highly H2S-sensitive SnO2 nanocrystals, which have been selectively prepared by solvothermal methods using benzimidazole as a mineralization agent. The sensitivity of as-obtained SnO2 sensor towards 5 ppm H2S can reach up to 357. Such a technique based on SnO2 nanocrystals opens up a promising avenue for future practical applications in real-time monitoring a trace of H2S from the leakage of biogas.

Mei, Lin; Chen, Yuejiao; Ma, Jianmin

2014-08-01

293

Microbial communities involved in biogas production from wheat straw as the sole substrate within a two-phase solid-state anaerobic digestion.  

PubMed

Microbial communities involved in biogas production from wheat straw as the sole substrate were investigated. Anaerobic digestion was carried out within an up-flow anaerobic solid-state (UASS) reactor connected to an anaerobic filter (AF) by liquor recirculation. Two lab-scale reactor systems were operated simultaneously at 37°C and 55°C. The UASS reactors were fed at a fixed organic loading rate of 2.5gL(-1)d(-1), based on volatile solids. Molecular genetic analyses of the bacterial and archaeal communities within the UASS reactors (digestate and effluent liquor) and the AFs (biofilm carrier and effluent liquor) were conducted under steady-state conditions. The thermophilic UASS reactor had a considerably higher biogas and methane yield in comparison to the mesophilic UASS, while the mesophilic AF was slightly more productive than the thermophilic AF. When the thermophilic and mesophilic community structures were compared, the thermophilic system was characterized by a higher Firmicutes to Bacteroidetes ratio, as revealed by 16S rRNA gene (rrs) sequence analysis. The composition of the archaeal communities was phase-separated under thermophilic conditions, but rather stage-specific under mesophilic conditions. Family- and order-specific real-time PCR of methanogenic Archaea supported the taxonomic distribution obtained by rrs sequence analysis. The higher anaerobic digestion efficiency of the thermophilic compared to the mesophilic UASS reactor was accompanied by a high abundance of Firmicutes and Methanosarcina sp. in the thermophilic UASS biofilm. PMID:25467556

Heeg, Kathrin; Pohl, Marcel; Sontag, Mario; Mumme, Jan; Klocke, Michael; Nettmann, Edith

2014-10-23

294

Performance Analysis of Potassium Heat Pipes Radiator for HP-STMCs Space Reactor Power System  

NASA Astrophysics Data System (ADS)

A detailed design and performance results of C-C finned, and armored potassium heat pipes radiator for a 110 kWe Heat Pipes-Segmented Thermoelectric Module Converters (HP-STMCs) Space Reactor Power system (SRPS) are presented. The radiator consists of two sections; each serves an equal number of STMCs and has 162 longitudinal potassium heat pipes with 0.508 mm thick C-C fins. The width of the C-C fins at the minor diameter of the radiator is almost zero, but increases with distance along the radiator to reach 3.7 cm at the radiator's major diameter. The radiator's heat pipes (OD = 2.42 cm in front and 3.03 cm in rear) have thin titanium (0.0762 mm thick) liners and wicks (0.20 mm thick with an effective pore radius of 12-16 ?m) and a 1.016 mm thick C-C wall. The wick is separated from the titanium liner by a 0.4 mm annulus filled with liquid potassium to increase the capillary limit. The outer surfaces of the heat pipes in the front and rear sections of the radiator are protected with a C-C armor that is 2.17 mm and 1.70 mm thick, respectively. The inside surface of the heat pipes in the front radiator is thermally insulated while the C-C finned condensers of the rear heat pipes are exposed, radiating into space through the rear opening of the radiator cavity. The heat pipes in both the front and the rear radiators have a 1.5 m long evaporator section and each dissipates 4.47 kW while operating at 43.6% of the prevailing sonic limit. The front and rear radiator sections are 5.29 m and 2.61 m long with outer surface area and mass of 47.1 m2 and 314.3 kg, and 39.9 m2 and 243.2 kg, respectively. The total radiator is 7.63 m long and has minor and major diameters of 1.48 m and 5.57 m, respectively, and a total surface area of 87 m2; however, the effective radiator area, after accounting for heat rejection through the rear of the radiator cavity, is 98.8 m2. The radiator's total mass including the C-C armor is 557.5 kg and the specific area and specific mass are 6.41 kg/m2 and 5.07 kg/kWe, respectively.

El-Genk, Mohamed S.; Tournier, Jean-Michel

2004-02-01

295

Factors Affecting Process Temperature and Biogas Production in Small-scale Rural Biogas Digesters in Winter in Northern Vietnam.  

PubMed

This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature (°C) at a depth of 140 cm and 180 cm, biogas production and methane (CH4) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank. PMID:25050049

Pham, C H; Vu, C C; Sommer, S G; Bruun, S

2014-07-01

296

Factors Affecting Process Temperature and Biogas Production in Small-scale Rural Biogas Digesters in Winter in Northern Vietnam  

PubMed Central

This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature (°C) at a depth of 140 cm and 180 cm, biogas production and methane (CH4) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank. PMID:25050049

Pham, C. H.; Vu, C. C.; Sommer, S. G.; Bruun, S.

2014-01-01

297

Performance of an upflow anaerobic reactor combining a sludge blanket and a filter treating sugar waste  

SciTech Connect

A new hybrid reactor, the upflow blanket filter (UBF), which combines an open volume in the bottom two-thirds of the reactor for a sludge blanket and submerged plastic rings (Flexiring, Koch Inc., 235 squared m/cubic m) in the upper one-third of the reactor volume, was studied. This UBF reactor was operated at 27 degrees C at loading rates varying from 5 to 51 g chemical oxygen demand (COD)/l day with soluble sugar wastewater (2500 mg COD/l). Maximum removal rates of 34 g COD/l day and CH/sub 4/ production rates of 7 vol/vol day (standard temperature and pressure (STP)) were obtained. The biomass activity was about 1.2 g COD/g volatile suspended solids per day. Conversion (based on effluent soluble COD) was over 93% with loading rates up to 26 g COD/l day. At higher loading rates conversion decreased rapidly. The packing was very efficient in retaining biomass. 11 references.

Guiot, S.R.; Van den Berg, L.

1985-06-01

298

Anaerobic treatment performance and microbial population of thermophilic upflow anaerobic filter reactor treating awamori distillery wastewater.  

PubMed

Distillery wastewater from awamori making was anaerobically treated for one year using thermophilic upflow anaerobic filter (UAF) reactors packed with pyridinium group-containing nonwoven fabric material. The microbial structure and spatial distribution of microorganisms on the support material were characterized using molecular biological methods. The reactor steadily achieved a high TOC loading rate of 18 g/l/d with approximately 80% TOC removal efficiency when non-diluted wastewater was fed. The maximum TOC loading rate increased to 36 g/l/d when treating thrice-diluted wastewater. However, the TOC removal efficiency and gas evolution rate decreased compared with that when non-diluted wastewater was used. Methanogens closely related to Methanosarcina thermophila and Methanoculleus bourgensis and bacteria in the phyla Firmicutes and Bacteroidetes were predominant methanogens and bacteria in the thermophilic UFA reactor, as indicated by 16S rRNA gene clone analysis. Fluorescence in situ hybridization (FISH) results showed that a large quantity of bacterial cells adhered throughout the whole support, and Methanosarcina-like methanogens existed mainly in the relative outside region while Methanoculleus cells were located in the relative inner part of the support. The support material used proved to be an excellent carrier for microorganisms, and a UAF reactor using this kind of support can be used for high-rate treatment of awamori/shochu distillery wastewater. PMID:18023800

Tang, Yue-Qin; Fujimura, Yutaka; Shigematsu, Toru; Morimura, Shigeru; Kida, Kenji

2007-10-01

299

Analysis of the performance of the Westinghouse reactor vessel level indicating system for tests at semiscale. [PWR  

SciTech Connect

The Westinghouse Reactor Vessel Level Indicating System (RVLIS), a differential pressure level measurement system, was tested at SEMISCALE. This report contains the analyses of these tests and the conclusions of these analyses. The tests performed included small break and intermediate break tests. Also, frequency response and natural circulation tests were run and analyzed. The RVLIS always indicated a level less than the two phase froth level. The RVLIS output in early small break tests indicated a level 200 cm greater than actual collapsed liquid level. This discrepancy was caused by structural differences between SEMISCALE and a Westinghouse reactor. Once modifications were made so that SEMISCALE better simulated a Westinghouse PWR, the maximum difference between RVLIS and SEMISCALE instrumentation was 30 cm or 3% which is less than the stated uncertainty of the Westinghouse RVLIS.

Hardy, J.E.; Miller, G.N.

1982-10-01

300

[Biogas production from cellulose-containing substrates: a review].  

PubMed

Anaerobic microbial conversion of organic substrates to various biofuels is one of the alternative energy sources attracting the greatest attention of scientists. The advantages of biogas production over other technologies are the ability of methanogenic communities to degrade a broad range of substrates and concomitant benefits: neutralization of organic waste, reduction of greenhouse gas emission, and fertilizer production. Cellulose-containing materials are a good substrate, but their full-scale utilization encounters a number of problems, including improvement of the quality and amount ofbiogas produced and maintenance of the stability and high efficiency of microbial communities. We review data on microorganisms that form methanogenic cellulolytic communities, enzyme complexes of anaerobes essential for cellulose fiber degradation, and feedstock pretreatment, as biodegradation is hindered in the presence of lignin. Methods for improving biogas production by optimization of microbial growth conditions are considered on the examples of biogas formation from various types of plant and paper materials: writing paper and cardboard. PMID:23101383

Tsavkelova, E A; Netrusov, A I

2012-01-01

301

Hydrogen in biogas and its impact to the atmosphere  

NASA Astrophysics Data System (ADS)

The shortage and increase in cost of fossil fuels leads to an increased interest in renewable energy sources. One important renewable energy source is biogas, produced by fermentation of organic material. During the last ten years the number of biogas plants has continuously increased and it is expected to increase further. Biogas is a mixture of mainly methane and carbon dioxide but contains also molecular hydrogen (H2). The hydrogen content of biogas depends on the used substrate and the production process. Hydrogen is also produced by conversion of biogas. Although hydrogen is considered as one of the most important future energy carriers, little is known about the global biogeochemical cycle of this trace gas (Rhee et al. 2006) and its impact to the atmosphere is discussed controversially. In order to assess the impact of an expected increasing H2 concentration to the atmosphere a fundamental understanding of the sources and sinks of the global H2 cycle is indispensable (Tromp et al. 2003, Warwick et al. 2004). Due to the large mass difference between hydrogen and deuterium the isotope composition is one possibility to obtain further information about the sources and sinks. Here we will present first results of the isotope composition of hydrogen in biogas. Literature Rhee, T.S., C.A.M. Brenninkmeijer, and T. Röckmann; The overwhelming role of soils in the global atmospheric hydrogen cycle, Atmos. Chem. Phys., 6, 1611-1625, 2006. Tromp, T.K., Shi, R.-L., Allen, M., Eiler, J.M., and Y. L. Yung1; Potential Environmental Impact of a Hydrogen Economy on the Stratosphere, Science, 300, 1740-1742, 2003. Warwick, N.J., Bekki, S., Nisbet, E.G., and J.A. Pyle; Impact of a hydrogen economy on the stratosphere and troposphere studied in a 2-D model; Geo.Res.Lett., 31, L05107, doi:10.1029/2003GL019224, 2004.

Walter, S.; Laukenmann, S.; Stams, A. J. M.; Röckmann, T.

2009-04-01

302

Effects of bed materials on the performance of an anaerobic sequencing batch biofilm reactor treating domestic sewage.  

PubMed

The objective of this study was to determine the best performance of an anaerobic sequencing batch biofilm reactor (AnSBBR) based on the use of four different bed materials as support for biomass immobilization. The bed materials utilized were polyurethane foam (PU), vegetal carbon (VC), synthetic pumice (SP), and recycled low-density polyethylene (PE). The AnSBBR, with a total volume of 7.2L, was operated in 8-h batch cycles over 10 months, and fed with domestic sewage with an average influent chemical oxygen demand (COD) of 358+/-110 mg/L. The average effluent COD values were 121+/-31, 208+/-54, 233+/-52, and 227+/-51 mg/L, for PU, VC, SP, and PE, respectively. A modified first-order kinetic model was adjusted to temporal profiles of COD during a batch cycle, and the apparent kinetic constants were 0.52+/-0.05, 0.37+/-0.05, 0.80+/-0.04, and 0.30+/-0.02 h(-1) for PU, VC, SP, and PE, respectively. Specific substrate utilization rates of 1.08, 0.11, and 0.86 mg COD/mg VS day were obtained for PU, VC, and PE, respectively. Although SP yielded the highest kinetic coefficient, PU was considered the best support, since SP presented loss of chemical constituents during the reactor's operational phase. In addition, findings on the microbial community were associated with the reactor's performance data. Although PE did not show a satisfactory performance, an interesting microbial diversity was found on its surface. Based on the morphology and denaturing gradient gel electrophoresis (DGGE) results, PE showed the best capacity for promoting the attachment of methanogenic organisms, and is therefore a material that merits further analysis. PU was considered the most suitable material showing the best performance in terms of efficiency of solids and COD removal. PMID:17765390

Garcia, M L; Lapa, K R; Foresti, E; Zaiat, M

2008-09-01

303

Performance evaluation of a continuous bipolar electrocoagulation\\/electrooxidation–electroflotation (ECEO–EF) reactor designed for simultaneous removal of ammonia and phosphate from wastewater effluent  

Microsoft Academic Search

The present study aimed to evaluate the performance of a continuous bipolar ECEO–EF reactor designed for simultaneous removal of ammonia and phosphate from wastewater effluent. The reactor was comprised of two distinct units: electrochemical and separation. In the electrochemical unit, Al, stainless steel, and RuO2\\/Ti plates were used. All the measurements were performed according to the standard methods. Maximum efficiency

Amir Hossein Mahvi; Seyed Jamal Al-din Ebrahimi; Alireza Mesdaghinia; Hamed Gharibi; Mohammad Hossein Sowlat

2011-01-01

304

Factors affecting the performances of sprayed chromium carbide coatings for gas-cooled reactor heat exchangers  

Microsoft Academic Search

The paper discusses some important factors to be considered for using sprayed coatings in gas-cooled reactor heat exchangers. These factors include (a) high-temperature gaseous corresion, (b) thermal stability of coatings, (c) metallurgical compatibility between the coating and substrate, and (d) effects of the coating on the mechanical properties of the substrate alloy. The coatings evaluated were CrâCâ--NiCr and CrââCâ--NiCr applied

G. Lai

1979-01-01

305

High temperature postirradiation materials performance of spent pressurized water reactor fuel rods under dry storage conditions  

Microsoft Academic Search

Postirradiation studies on failure mechanisms of well-characterized pressurized water reactor rods were conducted for up to a year at 482, 510, and 571°C in limited air and inert gas atmospheres. No cladding breaches occurred even though the tests operated many orders of magnitude longer in time than the lifetime predicted by Blackburn's analyses. The extended lifetime is due to significant

R. E. Einziger; S. D. Atkin; V. Pasupathi; D. E. Stellrecht

1982-01-01

306

Effects of staged vessels on dissolver performance. Internal R and D final report. [Staged reactors at different temperatures  

SciTech Connect

This report summarizes the work conducted under ICRC's Program Area 12.1.7, on the effects of staged vessels on dissolver performance. Results showed that operating the dissolvers in series decreased the preasphaltenes yield. From a process viewpoint, this should increase the amount of recoverable product, because recovery from the plant's critical solvent deashing unit will increase when preasphaltene content decreases. Neither conversion nor oil, asphaltene, or gas yields were affected by reactor configuration. Process data taken at residence times from 20 to 60 min and temperatures from 780 to 840/sup 0/F showed that oil yields were directly affected by reaction time, but relatively insensitive to temperature. Operating the dissolvers at staged temperatures may have some potential advantages. For Lafayette Kentucky number 9 coal, operating the first dissolver at 810/sup 0/F and the second at 840/sup 0/F, agreed with the results observed under similar conditions on Lafayette coal. By operating the first reactor at a lower temperature, the oil yields were improved, compared to operating both reactors at the same temperature. The hydrocarbon gas yields and hydrogen consumption were lower in the staged-temperature than in the isothermal mode. 8 references, 9 figures, 26 tables.

Sivasubramanian, R.; Givens, E.N.

1983-09-01

307

Effects of solid-phase mass transfer on the performance of a stirred anaerobic sequencing batch reactor containing immobilized biomass.  

PubMed

This work reports on experiments for an anaerobic sequencing batch reactor containing immobilized biomass which aimed at verifying the effects of solid-phase mass transfer on the reactor's overall performance. Four experiments were carried out at 30 degrees C with cubic polyurethane foam particles previously inoculated with anaerobic biomass. Different solid-phase mass transfer conditions were reached in each experiment by varying the size of the bioparticle from 0.5 to 3.0 cm. The reactor was fed with a low-strength synthetic wastewater containing protein, carbohydrates and lipid and the effects of mass transfer were evaluated through dynamic substrate concentration profiles during 8-hour batch cycles. A modified first-order kinetic model provided a good representation of the behavior of the dynamic concentration profiles. The solid-phase mass transfer was found to slightly affect the concentration of effluent organic matter expressed as chemical oxygen demand (COD). The concentration of residual effluent substrate increased as the size of the bioparticle was increased. The cycle time was not affected as the size of the bioparticle was increased from 0.5 to 2.0 cm. However, it was found that the cycle time in a reactor with 3.0-cm cubic particles should be higher than that required in systems with smaller particles. The apparent first-order kinetic parameter was estimated as 0.59+/-0.01 h(-1) for experiments with bioparticle sizes ranging from 0.5 to 2.0 cm, while a value of 0.48 h(-1) was obtained in the experiment with 3.0-cm bioparticles. PMID:16843658

Cubas, S A; Foresti, E; Rodrigues, J A D; Ratusznei, S M; Zaiat, M

2007-05-01

308

Optimization of biogas production using MEMS based near infrared inline-sensor  

NASA Astrophysics Data System (ADS)

Due to climate protection and increasing oil prices, renewable energy is becoming extremely important. Anaerobic digestion is a particular environmental and resource-saving way of heat and power production in biogas plants. These plants can be operated decentralized and independent of weather conditions and allow peak load operation. To maximize energy production, plants should be operated at a high efficiency. That means the entire installed power production capacity (e.g. CHP) and biogas production have to be used. However, current plant utilization in many areas is significantly lower, which is economically and environmentally inefficient, since the biochemical process responds to fluctuations in boundary conditions, e.g. mixing in the conditions and substrate composition. At present only a few easily accessible parameters such as fill level, flow rates and temperature are determined on-line. Monitoring of substrate composition occurs only sporadically with the help of laboratory methods. Direct acquisition of substrate composition combined with a smart control and regulation concept enables significant improvement in plant efficiency. This requires a compact, reliable and cost-efficient sensor. It is for this reason that a MEMS sensor system based on NIR spectroscopy has been developed. Requirements are high accuracy, which is the basic condition for exact chemometric evaluation of the sample as well as optimized MEMS design and packaging in order to work in poor environmental conditions. Another issue is sample presentation, which needs an exact adopted optical-mechanical system. In this paper, the development and application of a MEMS-based analyzer for biogas plants will be explained. The above mentioned problems and challenges will be discussed. Measurement results will be shown to demonstrate its performance.

Saupe, Ray; Seider, Thomas; Stock, Volker; Kujawski, Olaf; Otto, Thomas; Gessner, Thomas

2013-03-01

309

Enhanced performance of deuterium--tritium-fueled supershots using extensive lithium conditioning in the Tokamak Fusion Test Reactor  

SciTech Connect

In the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire {ital et} {ital al}., Phys. Plasmas {bold 2}, 2176 (1995)] a substantial improvement in fusion performance has been realized by combining the enhanced confinement due to tritium fueling with the enhanced confinement due to extensive conditioning of the limiter with lithium. This combination has resulted in not only significantly higher global energy confinement times than have previously been obtained in high current supershots, but also in the highest central ratio of thermonuclear fusion output power to input power observed to date. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Mansfield, D.K.; Strachan, J.D.; Bell, M.G.; Scott, S.D.; Budny, R.; Marmar, E.S.; Snipes, J.A.; Terry, J.L.; Batha, S.; Bell, R.E.; Bitter, M.; Bush, C.E.; Chang, Z.; Darrow, D.S.; Ernst, D.; Fredrickson, E.; Grek, B.; Herrmann, H.W.; Hill, K.W.; Janos, A.; Jassby, D.L.; Jobes, F.C.; Johnson, D.W.; Johnson, L.C.; Levinton, F.W.; Mikkelsen, D.R.; Mueller, D.; Owens, D.K.; Park, H.; Ramsey, A.T.; Roquemore, A.L.; Skinner, C.H.; Stevenson, T.; Stratton, B.C.; Synakowski, E.; Taylor, G.; von Halle, A.; von Goeler, S.; Wong, K.L.; Zweben, S.J. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)

1995-11-01

310

Micro-aeration for hydrogen sulfide removal from biogas  

Microsoft Academic Search

The presence of sulfur compounds (e.g. protein, sulfate, thiosulfate, sulfite, etc.) in the feed stream generates highly corrosive and odorous hydrogen sulfide during anaerobic digestion. The high sulfide level in the biogas stream is not only poisonous to many novel metal catalysts employed in thermo-catalytic processes but also reduces the quality of methane to produce renewable energy. This study used

Thanapong Duangmanee

2009-01-01

311

Biogas energy production from tropical biomass wastes by anaerobic digestion  

Technology Transfer Automated Retrieval System (TEKTRAN)

Anaerobic digestion (AD) is an attractive technology in tropical regions for converting locally abundant biomass wastes into biogas which can be used to produce heat, electricity, and transportation fuels. However, investigations on AD of tropical forestry wastes, such as albizia biomass, and food w...

312

The hydrolysis and biogas production of complex cellulosic substrates using three anaerobic biomass sources.  

PubMed

In this study, the ability of various sludges to digest a diverse range of cellulose and cellulose-derived substrates was assessed at different temperatures to elucidate the factors affecting hydrolysis. For this purpose, the biogas production was monitored and the specific biogas activity (SBA) of the sludges was employed to compare the performance of three anaerobic sludges on the degradation of a variety of complex cellulose sources, across a range of temperatures. The sludge with the highest performance on complex substrates was derived from a full-scale bioreactor treating sewage at 37 °C. Hydrolysis was the rate-limiting step during the degradation of complex substrates. No activity was recorded for the synthetic cellulose compound carboxymethylcellulose (CMC) using any of the sludges tested. Increased temperature led to an increase in hydrolysis rates and thus SBA values. The non-granular nature of the mesophilic sludge played a positive role in the hydrolysis of solid substrates, while the granular sludges proved more effective on the degradation of soluble compounds. PMID:23168626

Keating, C; Cysneiros, D; Mahony, T; O'Flaherty, V

2013-01-01

313

Molten carbonate fuel cells fed with biogas: combating H(2)S.  

PubMed

The use of biomass and waste to produce alternative fuels, due to environmental and energy security reasons, is a high-quality solution especially when integrated with high efficiency fuel cell applications. In this article we look into the coupling of an anaerobic digestion process of organic residues to electrochemical conversion to electricity and heat through a molten carbonate fuel cell (MCFC). In particular the pathway of the exceedingly harmful compound hydrogen sulphide (H(2)S) in these phases is analysed. Hydrogen sulphide production in the biogas is strongly interrelated with methane and/or hydrogen yield, as well as with operating conditions like temperature and pH. When present in the produced biogas, this compound has multiple negative effects on the performance and durability of an MCFC. Therefore, there are important issues of integration to be solved. Three general approaches to solve the sulphur problem in the MCFC are possible. The first is to prevent the formation of hydrogen sulphide at the source: favouring conditions that inhibit its production during fermentation. Secondly, to identify the sulphur tolerance levels of the fuel cell components currently in use and develop sulphur-tolerant components that show long-term electrochemical performance and corrosion stability. The third approach is to remove the generated sulphur species to very low levels before the gas enters the fuel cell. PMID:20211554

Ciccoli, R; Cigolotti, V; Lo Presti, R; Massi, E; McPhail, S J; Monteleone, G; Moreno, A; Naticchioni, V; Paoletti, C; Simonetti, E; Zaza, F

2010-06-01

314

Effects of organic loading rate on reactor performance and archaeal community structure in mesophilic anaerobic digesters treating municipal sewage sludge.  

PubMed

In this study, the organic loading rate (OLR) of a high-solids anaerobic digestion (HSAD) system was increased from 3.4 to 5.0?gVS?L(-1)?day(-1) and reactor stability, performance and microbial community structure were determined. Laboratory simulations (3.5?L) of the full-scale process (500?dry?ton?year(-1)) were conducted using continuously stirred-tank mesophilic reactors. OLRs of 3.4?gVS?L(-1)day(-1) (equal to the full-scale HSAD), 4.0, 4.5 and 5.0?gVS?L(-1)day(-1) were evaluated. Biochemical parameters and archaeal community dynamics were measured over 42 days of steady state operation. Results showed that increasing OLR increased the amount of organic matter conversion and resulted in higher organic matter removal and volumetric methane (CH?) production (VMP) rates. The highest volatile solids (VS) removal and VMP results of 54?±?2% and 1.4?±?0.1?L?CH??L(-1)day(-1) were observed for 5.0?gVS?L(-1)?day(-1). The efficiency of reactor conversion of organic matter to CH(4) was found to be similar in all the treatments with an average value of 0.57?±?0.07?LCH(4)?gVS(-1) (removed). 16S?rRNA gene terminal restriction fragment polymorphism (T-RFLP) analyses revealed that archaeal TRFs remained stable during the experiment accounting for an average relative abundance (RA) of 81?±?1%. Archaea consistent with multiple terminal restriction fragments (TRFs) included members of the Euryarchaeota and Crenarchaeota phyla, including acetoclastic and hydrogenotrophic groups. In conclusion, this laboratory-scale study suggests that performance and stability as well as the archaeal community structure in this HSAD system was unaffected by increasing the OLR by nearly 50% and that this increase resulted in a similar increase in the amount of CH(4) gas generated. PMID:21890875

Gómez, Eddie; Martin, Jay; Michel, Frederick C

2011-11-01

315

Effect of inlet temperature on the performance of a catalytic reactor. [air pollution control  

NASA Technical Reports Server (NTRS)

A 12 cm diameter by 15 cm long catalytic reactor was tested with No. 2 diesel fuel in a combustion test rig at inlet temperatures of 700, 800, 900, and 1000 K. Other test conditions included pressures of 3 and 6 x 10 to the 5th power Pa, reference velocities of 10, 15, and 20 m/s, and adiabatic combustion temperatures in the range 1100 to 1400 K. The combustion efficiency was calculated from measurements of carbon monoxide and unburned hydrocarbon emissions. Nitrogen oxide emissions and reactor pressure drop were also measured. At a reference velocity of 10 m/s, the CO and unburned hydrocarbons emissions, and, therefore, the combustion efficiency, were independent of inlet temperature. At an inlet temperature of 1000 K, they were independent of reference velocity. Nitrogen oxides emissions resulted from conversion of the small amount (135 ppm) of fuel-bound nitrogen in the fuel. Up to 90 percent conversion was observed with no apparent effect of any of the test variables. For typical gas turbine operating conditions, all three pollutants were below levels which would permit the most stringent proposed automotive emissions standards to be met.

Anderson, D. N.

1978-01-01

316

Initial Requirements for Gas-Cooled Fast Reactor (GFR) System Design, Performance, and Safety Analysis Models  

SciTech Connect

The gas-cooled fast reactor (GFR) was chosen as one of the Generation IV nuclear reactor systems to be developed based on its excellent potential for sustainability through reduction of the volume and radio toxicity of both its own fuel and other spent nuclear fuel, and for extending/utilizing uranium resources orders of magnitude beyond what the current open fuel cycle can realize. In addition, energy conversion at high thermal efficiency is possible with the current designs being considered, thus increasing the economic benefit of the GFR. However, research and development challenges include the ability to use passive decay heat removal systems during accident conditions, survivability of fuels and in-core materials under extreme temperatures and radiation, and economical and efficient fuel cycle processes. Nevertheless, the GFR was chosen as one of only six Generation IV systems to be pursued based on its ability to meet the Generation IV goals in sustainability, economics, safety and reliability, proliferation resistance and physical protection.

Kevan D. Weaver; Thomas Y. C. Wei

2004-08-01

317

Direct reforming of biogas on Ni-based SOFC anodes: Modelling of heterogeneous reactions and validation with experiments  

NASA Astrophysics Data System (ADS)

This work focuses on the heterogeneous reactions taking place in a tubular anode-supported solid oxide fuel cell (SOFC) when the designated fuel is biogas from anaerobic digestion directly feeding the fuel cell. Operational maps of the fuel cell running on direct reforming of biogas were first obtained. Hence a mathematical model incorporating the kinetics of reforming reactions on Ni catalyst was used to predict the gas composition profile along the fuel channel. The model was validated against experimental data based on polarization curves. Also, the anode off-gas composition was collected and analyzed through a gas chromatograph. Finally, the model has been used to predict and analyze the gas composition change along the anode channel to evaluate effectiveness of the direct steam reforming when varying cell temperature, inlet fuel composition and the type of reforming process. The simulations results confirmed that thermodynamic-equilibrium conditions are not fully achieved inside the anode channel. It also outlines that a direct biogas utilization in an anode-supported SOFC is able to provide good performance and to ensure a good conversion of the methane even though when the cell temperature is far from the nominal value.

Santarelli, Massimo; Quesito, Francesco; Novaresio, Valerio; Guerra, Cosimo; Lanzini, Andrea; Beretta, Davide

2013-11-01

318

Exergy & economic analysis of biogas fueled solid oxide fuel cell systems  

NASA Astrophysics Data System (ADS)

We present an exergy and an economic analysis of a power plant that uses biogas produced from a thermophilic anaerobic digester (AD) to fuel a solid oxide fuel cell (SOFC). We performed a 4-variable parametric analysis of the AD-SOFC system in order to determine the optimal design operation conditions, depending on the objective function of interest. We present results on the exergy efficiency (%), power normalized capital cost ($ kW-1), and the internal rate of return on investment, IRR, (% yr-1) as a function of the current density, the stack pressure, the fuel utilization, and the total air stoichiometric ratio. To the authors' knowledge, this is the first AD-SOFC paper to include the cost of the AD when conducting economic optimization of the AD-SOFC plant. Our calculations show that adding a new AD-SOFC system to an existing waste water treatment (WWT) plant could yield positives values of IRR at today's average electricity prices and could significantly out-compete other options for using biogas to generate electricity. AD-SOFC systems could likely convert WWT plants into net generators of electricity rather than net consumers of electricity while generating economically viable rates of return on investment if the costs of SOFC systems are within a factor of two of the DOE/SECA cost targets.

Siefert, Nicholas S.; Litster, Shawn

2014-12-01

319

Titania and alumina sol-gel-derived microfluidics enzymatic-reactors for peptide mapping: design, characterization, and performance.  

PubMed

The design and characterization of titania-based and alumina-based Poly(dimethylsiloxane) (PDMS) microfluidics enzymatic-reactors along with their analytical features in coupling with MALDI-TOF and ESI-MS were reported. Microfluidics with microchannel and stainless steel tubing (SST) were fabricated using PDMS casting and O(2)-plasma techniques, and were used for the preparation of an enzymatic-reactor. Plasma oxidation for the PDMS microfluidic system enabled the channel wall of the microfluidics to present a layer of silanol (SiOH) groups. These SiOH groups act as anchors onto the microchannel wall linked covalently with the hydroxyl groups of trypsin-encapsulated sol matrix. As a result, the trypsin-encapsulated gel matrix was anchored onto the wall of the microchannel, and the leakage of gel matrix from the microchannel was effectively prevented. A feature of the microfluidic enzymatic-reactors is the feasibility of performing on-line protein analysis by attached SST electrode and replaceable tip. The success of trypsin encapsulation was investigated by AFM imaging, assay of enzymatic activity, CE detection, and MALDI-TOF and ESI-MS analysis. The lab-made devices provide an excellent extent of digestion even at a fast flow rate of 7.0 microL/min, which affords the very short residence time of ca. 2 s. With the present device, the digestion time was significantly shortened compared to conventional tryptic reaction schemes. In addition, the encapsulated trypsin exhibits increased stability even after continuous use. These features are required for high-throughput protein identification. PMID:15595729

Wu, Huiling; Tian, Yuping; Liu, Baohong; Lu, Haojie; Wang, Xiaoyan; Zhai, Jianjun; Jin, Hong; Yang, Pengyuang; Xu, Yunmin; Wang, Honghai

2004-01-01

320

Anaerobic co-digestion of food waste and landfill leachate in single-phase batch reactors.  

PubMed

In order to investigate the effect of raw leachate on anaerobic digestion of food waste, co-digestions of food waste with raw leachate were carried out. A series of single-phase batch mesophilic (35±1°C) anaerobic digestions were performed at a food waste concentration of 41.8 g VS/L. The results showed that inhibition of biogas production by volatile fatty acids (VFA) occurred without raw leachate addition. A certain amount of raw leachate in the reactors effectively relieved acidic inhibition caused by VFA accumulation, and the system maintained stable with methane yield of 369-466 mL/g VS. Total ammonia nitrogen introduced into the digestion systems with initial 2000-3000 mgNH4-N/L not only replenished nitrogen for bacterial growth, but also formed a buffer system with VFA to maintain a delicate biochemical balance between the acidogenic and methanogenic microorganisms. UV spectroscopy and fluorescence excitation-emission matrix spectroscopy data showed that food waste was completely degraded. We concluded that using raw leachate for supplement water addition and pH modifier on anaerobic digestion of food waste was effective. An appropriate fraction of leachate could stimulate methanogenic activity and enhance biogas production. PMID:25062938

Liao, Xiaofeng; Zhu, Shuangyan; Zhong, Delai; Zhu, Jingping; Liao, Li

2014-11-01

321

Maximising biogas in anaerobic digestion by using engine waste heat for thermal hydrolysis pre-treatment of sludge.  

PubMed

Dublin's Ringsend WWTP was designed to serve a population of approximately 1.2 million p.e. with a sludge production of 37,000 dry tonnes per year after upgrading to full secondary treatment. Several technical solutions were put forward as part of a design, build, finance and operate (DBFO) competition, with the chosen solution being a proposal by Black and Veatch for a combination of sequencing batch reactor (SBR) technology and anaerobic digestion with Cambi thermal hydrolysis pre-treatment (THP). The THP plant was built by Cambi and handed over to B&V in 2002. The plant is now operated by Celtic Anglian Water. In September 2004 a test was carried out on the mass and energy balance of the plant following 2 years of operation and is detailed in this paper. The process enables digestion at very high dry solids feed and low hydraulic retention time. The plant was built with three digesters of 4250 m3 each and is fed with hydrolysed sludge at 11% DS. There are four no. 1 MW Jenbacher engines operating mainly on biogas. Each pair of engines is fitted with a waste heat boiler with a capacity of one tonne steam per hour. These boilers have sufficient capacity to provide 80% of the steam required for the THP, which in turn provides all the heat for the subsequent digestion in the form of hydrolysed feed. There are two main biogas boilers for top up steam and other uses of the biogas including thermal oxidation of concentrated odours. PMID:17087375

Pickworth, B; Adams, J; Panter, K; Solheim, O E

2006-01-01

322

Green energy from marine algae: biogas production and composition from the anaerobic digestion of Irish seaweed species.  

PubMed

Marine algae have emerged as an alternative feedstock for the production of a number of renewable fuels, including biogas. In addition to energy potential, other characteristics make them attractive as an energy source, including their ability to absorb carbon dioxide (CO2), higher productivity rates than land-based crops and the lack of water use or land competition. For Ireland, biofuels from marine algae can play an important role by reducing imports of fossil fuels as well as providing the necessary energy in rural communities. In this study, five potential seaweed species common in Irish waters, Saccorhiza polyschides, Ulva sp., Laminaria digitata, Fucus serratus and Saccharina latissima, were co-digested individually with bovine slurry. Batch reactors of 120ml and 1000ml were set up and incubated at 35 degrees C to investigate their suitability for production of biogas. Digesters fed with S. latissima produced the maximum methane yield (335 ml g volatile solids(-1) (g(VS)(-1) followed by S. polyschides with 255 ml g(VS)(-1). L. digitata produced 246ml g(VS)(-1) and the lowest yields were from the green seaweed Ulva sp. 191ml g(VS)(-1). The methane and CO2 percentages ranged between 50-72% and 10-45%, respectively. The results demonstrated that the seaweed species investigated are good feedstocks candidates for the production of biogas and methane as a source of energy. Their use on a large-scale process will require further investigation to increase yields and reduce production costs. PMID:24350482

Vanegas, C H; Bartlett, J

2013-01-01

323

Performance evaluation of a bipolar electrolysis/electrocoagulation (EL/EC) reactor to enhance the sludge dewaterability.  

PubMed

The present study aimed to evaluate the performance of a bipolar electrolysis/electrocoagulation reactor designed to enhance the sludge dewaterability. The reactor was 15 L in volume, with two series of plates used in it; Ti/RuO(2) plates for the electrolysis of the sludge, and also aluminum and iron plates for electrocoagulation process. The dewaterability of the sludge was determined in terms of its capillary suction time (CST) and specific resistance to filtration (SRF), while the degree of sludge disintegration was determined based on the value of degree of sludge disintegration (DD(SCOD)). The maximum reduction in CST and SRF was observed at a detention time of 20 min and a voltage of 30 V. However, increasing of both detention time and voltage significantly increased the values of CST and SRF even to an extent that they both exceeded those of the untreated sludge. The optimal degree of sludge disintegration achieved by the present study was 2.5%, which was also achieved at a detention time of 20 min and a voltage of 30V. As reported previously, increased DD(SCOD) values led to increasing CST and SRF values, due primarily to the disruption of the sludge flocs. According to the results from the present study, it can be concluded that simultaneous application of electrocoagulation and electrolysis is effective in enhancing the sludge dewaterability, because electrocoagulation helps to achieve a higher degree of sludge disintegration while maintaining the desired sludge dewaterability. PMID:23116826

Gharibi, Hamed; Sowlat, Mohammad Hossein; Mahvi, Amir Hossein; Keshavarz, Morteza; Safari, Mohammad Hossein; Lotfi, Saeedeh; Bahram Abadi, Mahnaz; Alijanzadeh, Azim

2013-01-01

324

Production of lightweight ceramisite from iron ore tailings and its performance investigation in a biological aerated filter (BAF) reactor.  

PubMed

The few reuse and large stockpile of iron ore tailings (IOT) led to a series of social and environmental problems. This study investigated the possibility of using the IOT as one of starting materials to prepare lightweight ceramisite (LWC) by a high temperature sintering process. Coal fly ash (CFA) and municipal sewage sludge (SS) were introduced as additives. The LWC was used to serve as a biomedium in a biological aerated filter (BAF) reactor for municipal wastewater treatment, and its purification performance was examined. The effects of sintering parameters on physical properties of the LWC, and leaching concentrations of heavy metals from the LWC were also determined. The microstructure and the phase composition of the LWC were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results revealed that: (1) IOT could be used to produce the LWC under the optimal sintering parameters; (2) the leaching concentrations of heavy metals from the LWC were well below their respective regulatory levels in the China Environmental Quality Standards for Surface Water (CEQS); and (3) the BAF reactor with the LWC serving as the biomedium achieved high removal efficiencies for COD(Cr) (>92%), NH(4)(+)-N (>62%) and total phosphate (T-P) (>63%). Therefore, the LWC produced from the IOT was suitable to serve as the biomedium in the municipal wastewater treatment. PMID:20227178

Liu, Yangsheng; Du, Fang; Yuan, Li; Zeng, Hui; Kong, Sifang

2010-06-15

325

Impact of increasing NaCl concentrations on the performance and community composition of two anaerobic reactors.  

PubMed

The anaerobic treatment of saline effluents using halophilic and halotolerant microbial consortia is of major interest. Inhibition of anaerobic digestion is known to occur at high salt content. However, it seems that the suitable adaptation of an anaerobic sludge makes possible the treatment of saline wastewater. In this study, a non-saline anaerobic sludge was inoculated in two anaerobic batch reactors operating with a different substrate (distillery vinasse and ethanol) and subjected to increasing NaCl concentrations. The performance of the digesters appeared to be highly dependent on the nature of the substrate, and a similar level of inhibition (i.e. around 90% of the specific loading rate and specific methanogenic activity) was stated at 10 g l(-1) of NaCl with distillery vinasse and 60 g l(-1) of NaCl with ethanol. The characterization of the microflora and its adaptation to increasing NaCl conditions were also investigated using molecular tools based on the analysis of genomic 16S rDNA. The microbial communities revealed a high diversity that could be maintained in both reactors despite the increase in NaCl concentrations. PMID:17245575

Lefebvre, O; Quentin, S; Torrijos, M; Godon, J J; Delgenès, J P; Moletta, R

2007-05-01

326

High-productivity continuous biofilm reactor for butanol production: effect of acetate, butyrate, and corn steep liquor on bioreactor performance.  

PubMed

Corn steep liquor (CSL), a byproduct of the corn wet-milling process, was used in an immobilized cell continuous biofilm reactor to replace the expensive P2 medium ingredients. The use of CSL resulted in the production of 6.29 g/L of total acetone-butanol-ethanol (ABE) as compared with 6.86 g/L in a control experiment. These studies were performed at a dilution rate of 0.32 h-1. The productivities in the control and CSL experiment were 2.19 and 2.01 g/(L.h), respectively. Although the use of CSL resulted in a 10% decrease in productivity, it is viewed that its application would be economical compared to P2 medium. Hence, CSL may be used to replace the P2 medium. It was also demonstrated that inclusion of butyrate into the feed was beneficial to the butanol fermentation. A control experiment produced 4.77 g/L of total ABE, and the experiment with supplemented sodium butyrate produced 5.70 g/L of total ABE. The butanol concentration increased from 3.14 to 4.04 g/L. Inclusion of acetate in the feed medium of the immobilized cell biofilm reactor was not found to be beneficial for the ABE fermentation, as reported for the batch ABE fermentation. PMID:15054287

Qureshi, Nasib; Karcher, Patrick; Cotta, Michael; Blaschek, Hans P

2004-01-01

327

Performance of a sulfide-oxidizing, sulfur-producing membrane biofilm reactor treating sulfide-containing bioreactor effluent.  

PubMed

Sulfide-containing waste streams are generated in mining, petrochemical plants, tanneries, viscose rayon manufacture, and the gasification of coal. Colorless sulfur bacteria can oxidize sulfide to elemental sulfur (S°), which can be recovered, when oxygen is their electron acceptor. This study evaluated sulfide oxidation and S° recovery in an oxygen-based membrane biofilm reactor (MBfR) treating the effluent from a sulfidogenic anaerobic baffled reactor. Sulfide oxidation efficiency (37-99%) and S° recovery (64-89% of oxidized sulfide) could be controlled by manipulating the sulfide loading, oxygen pressure to the fibers, and hydraulic retention time (HRT). For example, too-low oxygen pressure decreased S° recovery due to decreased sulfide oxidation, but too-high oxygen pressure lowered S° recovery due to its oxidation to sulfate. Most importantly, high sulfide oxidation (>98%) and conversion to S° (>75%) could be achieved together when the sulfide loading was less than 1.7 mol/m²·d and the O? pressure was sufficient to give an O? flux of at least 1.5 mol/m²·d. However, higher sulfide loading could be compensated by a higher O? pressure, and the best performance occurred when the sulfide loading was high (2 molS/m²·d), the O? pressure was high (?1 atm), and the HRT was short (1.9 h). Membrane fouling caused a low O? flux, which led to low sulfide-oxidation efficiency, but fouling could be reversed by mild acid washing. PMID:21452867

Sahinkaya, Erkan; Hasar, Halil; Kaksonen, Anna H; Rittmann, Bruce E

2011-05-01

328

Performance Indicator Program for US Department of Energy reactors and facilities  

Microsoft Academic Search

The US Department of Energy (DOE) is developing a Performance Indicator (PI) Program for all facilities. The objective is to periodically collect, statistically analyze and present performance-related information in a concise and consistent format for DOE and safety of facility operations. A set of 14 DOE-Hq. defined PI's has been established after review of programs used by other organizations. Since

R. Sastry; J. R. Fielding; B. J. Snyder; J. Usher; J. Boccio

1991-01-01

329

Defluoridation of drinking water by electrocoagulation/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor.  

PubMed

Defluoridation using batch electrocoagulation/electroflotation (EC/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The same trends were observed in both reactors, but the efficiency was higher in the STR at the beginning of the electrolysis, whereas similar values were usually achieved after 15min operation. The influence of the initial pH was explained using the analyses of sludge composition and residual soluble aluminum species in the effluents, and it was related to the prevailing mechanisms of defluoridation. Fluoride removal and sludge reduction were both favored by an initial pH around 4, but this value required an additional pre-treatment for pH adjustment. Finally, electric energy consumption was similar in both reactors when current density was lower than 12mA/cm(2), but mixing and complete flotation of the pollutants were achieved without additional mechanical power in the ELAR, using only the overall liquid recirculation induced by H(2) microbubbles generated by water electrolysis, which makes subsequent treatments easier to carry out. PMID:19375221

Essadki, A H; Gourich, B; Vial, Ch; Delmas, H; Bennajah, M

2009-09-15

330

Monitoring of sulfur dioxide emission resulting from biogas utilization on commercial pig farms in Taiwan.  

PubMed

The objective of this work tends to promote methane content in biogas and evaluate sulfur dioxide emission from direct biogas combustion without desulfurization. Analytical results of biogas combustion showed that combustion of un-desulfurized biogas exhausted more than 92 % of SO2 (P?biogas (P?biogas before any applications. PMID:25404540

Su, Jung-Jeng; Chen, Yen-Jung

2015-01-01

331

Optimization of a heterogeneous catalytic hydrodynamic cavitation reactor performance in decolorization of Rhodamine B: application of scrap iron sheets.  

PubMed

A low pressure pilot scale hydrodynamic cavitation (HC) reactor with 30 L volume, using fixed scrap iron sheets, as the heterogeneous catalyst, with no external source of H2O2 was devised to investigate the effects of operating parameters of the HC reactor performance. In situ generation of Fenton reagents suggested an induced advanced Fenton process (IAFP) to explain the enhancing effect of the used catalyst in the HC process. The reactor optimization was done based upon the extent of decolorization (ED) of aqueous solution of Rhodamine B (RhB). To have a perfect study on the pertinent parameters of the heterogeneous catalyzed HC reactor, the following cases as, the effects of scrap iron sheets, inlet pressure (2.4-5.8 bar), the distance between orifice plates and catalyst sheets (submerged and inline located orifice plates), back-pressure (2-6 bar), orifice plates type (4 various orifice plates), pH (2-10) and initial RhB concentration (2-14 mg L(-1)) have been investigated. The results showed that the highest cavitational yield can be obtained at pH 3 and initial dye concentration of 10 mg L(-1). Also, an increase in the inlet pressure would lead to an increase in the ED. In addition, it was found that using the deeper holes (thicker orifice plates) would lead to lower ED, and holes with larger diameter would lead to the higher ED in the same cross-sectional area, but in the same holes' diameters, higher cross-sectional area leads to the lower ED. The submerged operation mode showed a greater cavitational effects rather than the inline mode. Also, for the inline mode, the optimum value of 3 bar was obtained for the back-pressure condition in the system. Moreover, according to the analysis of changes in the UV-Vis spectra of RhB, both degradation of RhB chromophore structure and N-deethylation were occurred during the catalyzed HC process. PMID:23714332

Basiri Parsa, Jalal; Ebrahimzadeh Zonouzian, Seyyed Alireza

2013-11-01

332

Resolving operational and performance problems encountered in the use of a pilot/full-scale biotrickling filter reactor  

SciTech Connect

A pilot/full-scale biotrickling filter reactor experiment was performed at an industrial site to treat styrene laden waste gas. The engineered system consisted of two stainless steel tanks in series, each with filter bed volumes of 4.0 m{sup 3}, filled with 3.5-inch plastic spheres. The system treated 340 m{sup 3} h{sup {minus}1} of air laden with styrene concentrations ranging up to 0.8 g m{sup {minus}3}. Over the five-month study, styrene elimination was demonstrated up to 24 g m{sup {minus}3} H{sup {minus}1} with 70 to 85% removal. Operational and performance problems were identified that differ from those developed under controlled, laboratory set-ups. Operational problems typically involved equipment malfunctions, with the most prone to failure pieces of equipment being the air sampling system and water level sensors. Performance problems were identified that possibly limited the styrene removal. The transient operation of the plant, producing discontinuous, unsteady-state concentrations, made it difficult to establish a stable biofilm on the packing material. Experiments were performed indicating both biological and mass transfer limitations may have occurred.

Webster, T.S.; Cox, H.H.J.; Deshusses, M.A.

1999-09-30

333

Steam generator materials performance in high temperature gas-cooled reactors  

SciTech Connect

This paper reviews the materials technology aspects of steam generators for HTGRs which feature a graphite-moderated, uranium-thorium, all-ceramic core and utilizes high-pressure helium as the primary coolant. The steam generators are exposed to gas-side temperatures approaching 760/sup 0/C and produce superheated steam at 538/sup 0/C and 16.5 MPa (2400 psi). The prototype Peach Bottom I 40-MW(e) HTGR was operated for 1349 EFPD over 7 years. Examination after decommissioning of the U-tube steam generators and other components showed the steam generators to be in very satisfactory condition. The 330-MW(e) Fort St. Vrain HTGR, now in the final stages of startup, has achieved 70% power and generated more than 1.5 x 10/sup 6/ MWh of electricity. The steam generators in this reactor are once-through units of helical configuration, requiring a number of new materials factors including creep-fatigue and water chemistry control. Current designs of larger HTGRs also feature steam generators of helical once-through design. Materials issues that are important in these designs include detailed consideration of time-dependent behavior of both base metals and welds, as required by current American Society of Mechanical Engineers (ASME) Code rules, evaluation of bimetallic weld behavior, evaluation of the properties of large forgings, etc.

Chafey, J.E.; Roberts, D.I.

1980-11-01

334

Assessment of simulated biogas as a fuel for the spark ignition engine  

Microsoft Academic Search

Results are presented of tests with a variable compression ratio Ricardo E6 single-cylinder spark-ignition engine operating on simulated biogas formed from different mixtures of domestic natural gas and carbon dioxide. The fraction of carbon dioxide in the simulated biogas was changed from 0 to about 40% by volume to cover the range typically encountered in sources of biogas in practice.

Jingdang Huang; R. J Crookes

1998-01-01

335

Biogas scrubbing, compression and storage: perspective and prospectus in Indian context  

Microsoft Academic Search

Biogas is a clean environment friendly fuel. Raw biogas contains about 55–65% methane (CH4), 30–45% carbon dioxide (CO2), traces of hydrogen sulfide (H2S) and fractions of water vapours. Presently, it can be used only at the place where it is produced. There is a great need to make biogas transportable. This can be done by compressing the gas in cylinders

S. S. Kapdi; V. K. Vijay; S. K. Rajesh; Rajendra Prasad

2005-01-01

336

Monitoring feedwater flow rate and component thermal performance of pressurized water reactors by means of artificial neural networks  

SciTech Connect

The fouling of venturi meters, used for steam generator feedwater flow rate measurement in pressurized water reactors (PWRs), may result in unnecessary plant power derating. On-line monitoring of these important instrument channels and the thermal efficiencies of the balance-of-plant components are addressed. The steam generator feedwater flow rate and thermal efficiencies of critical components in a PWR are estimated by means of artificial neural networks. The physics of these systems and appropriate plant measurements are combined to establish robust neural network models for on-line prediction of feedwater flow rate and thermal efficiency of feedwater heaters in PWRs. A statistical sensitivity analysis technique was developed to establish the performance of this methodology.

Kavaklioglu, K.; Upadhyaya, B.R. (Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering)

1994-07-01

337

Transmutation Performance Analysis for Inert Matrix Fuels in Light Water Reactors and Computational Neutronics Methods Capabilities at INL  

SciTech Connect

The urgency for addressing repository impacts has grown in the past few years as a result of Spent Nuclear Fuel (SNF) accumulation from commercial nuclear power plants. One path that has been explored by many is to eliminate the transuranic (TRU) inventory from the SNF, thus reducing the need for additional long term repository storage sites. One strategy for achieving this is to burn the separated TRU elements in the currently operating U.S. Light Water Reactor (LWR) fleet. Many studies have explored the viability of this strategy by loading a percentage of LWR cores with TRU in the form of either Mixed Oxide (MOX) fuels or Inert Matrix Fuels (IMF). A task was undertaken at INL to establish specific technical capabilities to perform neutronics analyses in order to further assess several key issues related to the viability of thermal recycling. The initial computational study reported here is focused on direct thermal recycling of IMF fuels in a heterogeneous Pressurized Water Reactor (PWR) bundle design containing Plutonium, Neptunium, Americium, and Curium (IMF-PuNpAmCm) in a multi-pass strategy using legacy 5 year cooled LWR SNF. In addition to this initial high-priority analysis, three other alternate analyses with different TRU vectors in IMF pins were performed. These analyses provide comparison of direct thermal recycling of PuNpAmCmCf, PuNpAm, PuNp, and Pu. The results of this infinite lattice assembly-wise study using SCALE 5.1 indicate that it may be feasible to recycle TRU in this manner using an otherwise typical PWR assembly without violating peaking factor limits.

Michael A. Pope; Samuel E. Bays; S. Piet; R. Ferrer; Mehdi Asgari; Benoit Forget

2009-05-01

338

Process development of hydrogenous gas production for PEFC from biogas  

Microsoft Academic Search

A laboratory-scale gas processor that integrates four successive catalytic reactions: steam reforming of methane, high- and low-temperature water gas shifts and selective oxidation of carbon monoxide, was designed and tested in this study to produce hydrogen-rich gas with CO<10 ppm from a clean model biogas having a constant molar ratio of CH4\\/CO2=1.5:1.0 for a 50-W class polymer electrolyte fuel cell

Zhan-Guo Zhang; Guangwen Xu; Xin Chen; Kazunori Honda; Tadashi Yoshida

2004-01-01

339

Biogas as a fuel source for SOFC co-generators  

Microsoft Academic Search

This study reports on the combination of solid oxide fuel cell (SOFC) generators fueled with biogas as renewable energy source, recoverable from wastes but at present underexploited. From a mobilisable near-future potential in the European Union (EU-15) of 17 million tonnes oil equivalent (Mtoe), under 15% appears to be converted today into useful heat and power (2Mtoe).SOFCs could improve and

Jan Van herle; Yves Membrez; Olivier Bucheli

2004-01-01

340

Color removal from aqueous solution by biogas residual slurry  

Microsoft Academic Search

The adsorption of Acid Brilliant Blue on biogas residual slurry has been investigated. The parameters studied include dye concentration, agitation time, adsorbent dosage and pH. The equilibrium data fit well with both the Langmuir and Freundlich models of adsorption isotherm. Maximum removal of 99% was observed at pH 2.56. Desorption studies indicate that the dye is solubilised in 50%(v\\/v) acetic

R. T. Yamuna; C. Namasivayam

1993-01-01

341

Production of Methane Biogas as Fuel Through Anaerobic Digestion  

Microsoft Academic Search

\\u000a Anaerobic digestion (AD) is a biotechnology by which biomass is converted by microbes to methane (CH4) biogas, which can then be utilized as a renewable fuel to generate heat and electricity. A genetically and metabolically\\u000a diverse community of microbes (mainly bacteria and methanogens) drives the AD process through a series of complex microbiological\\u000a processes in the absence of oxygen. During

Zhongtang Yu; Floyd L. Schanbacher

342

Detection of pathogenic clostridia in biogas plant wastes.  

PubMed

As the number of biogas plants has grown rapidly in the last decade, the amount of potentially contaminated wastes with pathogenic Clostridium spp. has increased as well. This study reports the results from examining 203 biogas plant wastes (BGWs). The following Clostridium spp. with different frequencies could be isolated via a new enrichment medium (Krüne medium) and detected by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS): Clostridium perfringens (58 %) then Clostridium bifermentans (27 %), Clostridium tertium (23 %) and Clostridium butyricum (19 %), Clostridium cadaveris (15 %), Clostridium parapurificum (6 %), Clostridium glycolicum (5 %), Clostridium baratii (4 %), Clostridium sporogenes (2?%), Clostridium sordellii (1 %) and Clostridium subterminale (0.5 %). The mean most probable number (MPN) count of sulfite reducing bacteria was between 10(3) and 10(4)/mL, and the higher the MPN, the more pathogenic Clostridium spp. were present. Also, real-time PCR was used to be compared with culture method for C. perfringens, C. bifermentans, C. butyricum, C. sporogenes/Clostridium botulinum and C. sordellii. Although real-time PCR was more sensitive than the culture method, both systems improve the recovery rate but in different ways and are useful to determine pathogenic clostridia in biogas plants. In conclusion, BGWs could present a biohazard risk of clostridia for humans and animals. PMID:24984829

Neuhaus, Jürgen; Shehata, Awad A; Krüger, Monika

2015-01-01

343

Two-stage high-rate biogas (H2 and CH4) production from food waste using anaerobic mixed microflora  

NASA Astrophysics Data System (ADS)

To achieve the high-rate H2 and CH4 production from food waste using fermentative anaerobic microflora, the effects of carbonate-alkalinity in the recirculated digestion sludge on continuous two-stage fermentation were investigated. Higher H2 production rate of 2.9 L-H2/L/day was achieved at the recycle ratio of 1.0 in an alkalinity range of 9000 to 10000 mg-CaCO3/L. The maximum CH4 production rate was stably maintained at the range of 1.85 to 1.88 L-CH4/L/day without alkalinity change. Carbonate alkalinity in digestion sludge could reduce the H2 partial pressure in the headspace of the fermentation reactors, and improve a biogas production capacity in the two-stage fermentation process. The average volatile solids degradation rate in the overall process increased as the digestion sludge recycle increased from 0.5 to 1.0. These results show that the alkalinity in recycle of the digestion sludge is crucial factor in determining biogas (H2 and CH4) production capacity and reducing the total solids.

Xu, K.; Lee, D.; Kobayashi, T.; Ebie, Y.; Li, Y.; Inamori, Y.

2010-12-01

344

Root-cause analysis of the better performance of the coarse-mesh finite-difference method for CANDU-type reactors  

SciTech Connect

Recent assessment results indicate that the coarse-mesh finite-difference method (FDM) gives consistently smaller percent differences in channel powers than the fine-mesh FDM when compared to the reference MCNP solution for CANDU-type reactors. However, there is an impression that the fine-mesh FDM should always give more accurate results than the coarse-mesh FDM in theory. To answer the question if the better performance of the coarse-mesh FDM for CANDU-type reactors was just a coincidence (cancellation of errors) or caused by the use of heavy water or the use of lattice-homogenized cross sections for the cluster fuel geometry in the diffusion calculation, three benchmark problems were set up with three different fuel lattices: CANDU, HWR and PWR. These benchmark problems were then used to analyze the root cause of the better performance of the coarse-mesh FDM for CANDU-type reactors. The analyses confirm that the better performance of the coarse-mesh FDM for CANDU-type reactors is mainly caused by the use of lattice-homogenized cross sections for the sub-meshes of the cluster fuel geometry in the diffusion calculation. Based on the analyses, it is recommended to use 2 x 2 coarse-mesh FDM to analyze CANDU-type reactors when lattice-homogenized cross sections are used in the core analysis. (authors)

Shen, W. [Candu Energy Inc., 2285 Speakman Dr., Mississauga, ON L5B 1K (Canada)

2012-07-01

345

Calculational methodology and associated uncertainties: Sensitivity and uncertainty analysis of reactor performance parameters  

Microsoft Academic Search

This chapter considers the calculational methodology and associated uncertainties both for the design of large LMFBR's and the analysis of critical assemblies (fast critical experiments) as performed by several groups within the US. Discusses cross-section processing; calculational methodology for the design problem; core physics computations; design-oriented approximations; benchmark analyses; and determination of calculational corrections and associated uncertainties for a critical

E. Kujawski; C. R. Weisbin

1982-01-01

346

International Thermonuclear Experimental Reactor (ITER) divertor plate performance and lifetime considerations  

SciTech Connect

The ITER divertor plate performance during the technology phase of operation has been analyzed. High-Z materials, such as tungsten and tantalum, have been considered as plasma side materials, and refractory metal alloys, Ta-10W, TZM, Nb-1Zr, and V-15Cr-5Ti, plus copper alloys have been considered as the structural materials. The fatigue lifetime have been predicted for structural plates and for duplex plates with the plasma side material bonded to the structure. The results indicate that refractory alloys have a comparable or improved performance to copper alloys. Peak allowable heat fluxes for these analyses are in the range of 15--20 MW/m{sup 2} for 2 mm thick structural plates and 7--11 MW/m{sup 2} for 4 mm thick duplex plates. 4 refs., 55 figs., 6 tabs.

Mattas, R.F.

1990-03-01

347

Improved Dechlorinating Performance of Upflow Anaerobic Sludge Blanket Reactors by Incorporation of Dehalospirillum multivorans into Granular Sludge  

PubMed Central

Dechlorination of tetrachloroethene, also known as perchloroethylene (PCE), was investigated in an upflow anaerobic sludge blanket (UASB) reactor after incorporation of the strictly anaerobic, reductively dechlorinating bacterium Dehalospirillum multivorans into granular sludge. This reactor was compared to the reference 1 (R1) reactor, where the granules were autoclaved to remove all dechlorinating abilities before inoculation, and to the reference 2 (R2) reactor, containing only living granular sludge. All three reactors were fed mineral medium containing 3 to 57 ?M PCE, 2 mM formate, and 0.5 mM acetate and were operated under sterile conditions. In the test reactor, an average of 93% (mole/mole) of the effluent chloroethenes was dichloroethene (DCE), compared to 99% (mole/mole) in the R1 reactor. The R2 reactor, with no inoculation, produced only trichloroethene (TCE), averaging 43% (mole/mole) of the effluent chloroethenes. No dechlorination of PCE was observed in an abiotic control consisting of sterile granules without inoculum. During continuous operation with stepwise-reduced hydraulic retention times (HRTs), both the test reactor and the R1 reactor showed conversion of PCE to DCE, even at HRTs much lower than the reciprocal maximum specific growth rate of D. multivorans, indicating that this bacterium was immobilized in the living and autoclaved granular sludge. In contrast, the R2 reactor, with no inoculation of D. multivorans, only converted PCE to TCE under the same conditions. Immobilization could be confirmed by using fluorescein-labeled antibody probes raised against D. multivorans. In granules obtained from the R1 reactor, D. multivorans grew mainly in microcolonies located in the centers of the granules, while in the test reactor, the bacterium mainly covered the surfaces of granules. PMID:9572963

Hörber, Christine; Christiansen, Nina; Arvin, Erik; Ahring, Birgitte K.

1998-01-01

348

Biogas and Fuel Cells Workshop Summary Report: Proceedings from the Biogas and Fuel Cells Workshop, Golden, Colorado, June 11-13, 2012  

SciTech Connect

The U.S. Department of Energy (DOE) National Renewable Energy Laboratory (NREL) held a Biogas and Fuel Cells Workshop June 11-13, 2012, in Golden, Colorado, to discuss biogas and waste-to-energy technologies for fuel cell applications. The overall objective was to identify opportunities for coupling renewable biomethane with highly efficient fuel cells to produce electricity; heat; combined heat and power (CHP); or combined heat, hydrogen and power (CHHP) for stationary or motive applications. The workshop focused on biogas sourced from wastewater treatment plants (WWTPs), landfills, and industrial facilities that generate or process large amounts of organic waste, including large biofuel production facilities (biorefineries).

Not Available

2013-01-01

349

Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation  

PubMed Central

Anaerobic digestion (AD) is a bioprocess that is commonly used to convert complex organic wastes into a useful biogas with methane as the energy carrier 1-3. Increasingly, AD is being used in industrial, agricultural, and municipal waste(water) treatment applications 4,5. The use of AD technology allows plant operators to reduce waste disposal costs and offset energy utility expenses. In addition to treating organic wastes, energy crops are being converted into the energy carrier methane 6,7. As the application of AD technology broadens for the treatment of new substrates and co-substrate mixtures 8, so does the demand for a reliable testing methodology at the pilot- and laboratory-scale. Anaerobic digestion systems have a variety of configurations, including the continuously stirred tank reactor (CSTR), plug flow (PF), and anaerobic sequencing batch reactor (ASBR) configurations 9. The CSTR is frequently used in research due to its simplicity in design and operation, but also for its advantages in experimentation. Compared to other configurations, the CSTR provides greater uniformity of system parameters, such as temperature, mixing, chemical concentration, and substrate concentration. Ultimately, when designing a full-scale reactor, the optimum reactor configuration will depend on the character of a given substrate among many other nontechnical considerations. However, all configurations share fundamental design features and operating parameters that render the CSTR appropriate for most preliminary assessments. If researchers and engineers use an influent stream with relatively high concentrations of solids, then lab-scale bioreactor configurations cannot be fed continuously due to plugging problems of lab-scale pumps with solids or settling of solids in tubing. For that scenario with continuous mixing requirements, lab-scale bioreactors are fed periodically and we refer to such configurations as continuously stirred anaerobic digesters (CSADs). This article presents a general methodology for constructing, inoculating, operating, and monitoring a CSAD system for the purpose of testing the suitability of a given organic substrate for long-term anaerobic digestion. The construction section of this article will cover building the lab-scale reactor system. The inoculation section will explain how to create an anaerobic environment suitable for seeding with an active methanogenic inoculum. The operating section will cover operation, maintenance, and troubleshooting. The monitoring section will introduce testing protocols using standard analyses. The use of these measures is necessary for reliable experimental assessments of substrate suitability for AD. This protocol should provide greater protection against a common mistake made in AD studies, which is to conclude that reactor failure was caused by the substrate in use, when really it was improper user operation 10. PMID:22824993

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

2012-01-01

350

Performance simulation of a wall-type reactor in which exothermic and endothermic reactions proceed simultaneously, comparing with that of a fixed-bed reactor  

Microsoft Academic Search

By combining endothermic and exothermic reactions in one reactor, a mutual utilization of thermal energy involved in reactions is expected to produce a saving energy and a cost-down for running in industrial reaction process. In this case, a wall-type reaction system is thought to be suitable because such reaction system is good at exchangeability of thermal energy by conductive heat

Choji Fukuhara; Akira Igarashi

2005-01-01

351

Individual plant examination program: Perspectives on reactor safety and plant performance. Parts 2--5: Final report; Volume 2  

SciTech Connect

This report provides perspectives gained by reviewing 75 Individual Plant Examination (IPE) submittals pertaining to 108 nuclear power plant units. IPEs are probabilistic analyses that estimate the core damage frequency (CDF) and containment performance for accidents initiated by internal events. The US Nuclear Regulatory Commission (NRC) reviewed the IPE submittals with the objective of gaining perspectives in three major areas: (1) improvements made to individual plants as a result of their IPEs and the collective results of the IPE program, (2) plant-specific design and operational features and modeling assumptions that significantly affect the estimates of CDF and containment performance, and (3) strengths and weaknesses of the models and methods used in the IPEs. These perspectives are gained by assessing the core damage and containment performance results, including overall CDF, accident sequences, dominant contributions to component failure and human error, and containment failure modes. Methods, data, boundary conditions, and assumptions used in the IPEs are considered in understanding the differences and similarities observed among the various types of plants. This report is divided into three volumes containing six parts. Part 1 is a summary report of the key perspectives gained in each of the areas identified above, with a discussion of the NRC`s overall conclusions and observations. Part 2 discusses key perspectives regarding the impact of the IPE Program on reactor safety. Part 3 discusses perspectives gained from the IPE results regarding CDF, containment performance, and human actions. Part 4 discusses perspectives regarding the IPE models and methods. Part 5 discusses additional IPE perspectives. Part 6 contains Appendices A, B and C which provide the references of the information from the IPEs, updated PRA results, and public comments on draft NUREG-1560 respectively.

NONE

1997-12-01

352

Individual plant examination program: Perspectives on reactor safety and plant performance. Part 1: Final summary report; Volume 1  

SciTech Connect

This report provides perspectives gained by reviewing 75 Individual Plant Examination (IPE) submittals pertaining to 108 nuclear power plant units. IPEs are probabilistic analyses that estimate the core damage frequency (CDF) and containment performance for accidents initiated by internal events. The US Nuclear Regulatory Commission (NRC) reviewed the IPE submittals with the objective of gaining perspectives in three major areas: (1) improvements made to individual plants as a result of their IPEs and the collective results of the IPE program, (2) plant-specific design and operational features and modeling assumptions that significantly affect the estimates of CDF and containment performance, and (3) strengths and weaknesses of the models and methods used in the IPEs. These perspectives are gained by assessing the core damage and containment performance results, including overall CDF, accident sequences, dominant contributions to component failure and human error, and containment failure modes. Methods, data, boundary conditions, and assumptions used in the IPEs are considered in understanding the differences and similarities observed among the various types of plants. This report is divided into three volumes containing six parts. Part 1 is a summary report of the key perspectives gained in each of the areas identified above, with a discussion of the NRC`s overall conclusions and observations. Part 2 discusses key perspectives regarding the impact of the IPE Program on reactor safety. Part 3 discusses perspectives gained from the IPE results regarding CDF, containment performance, and human actions. Part 4 discusses perspectives regarding the IPE models and methods. Part 5 discusses additional IPE perspectives. Part 6 contains Appendices A, B and C which provide the references of the information from the IPEs, updated PRA results, and public comments on draft NUREG-1560 respectively.

NONE

1997-12-01

353

Effect of particle size on the performance of autotrophic nitrogen removal in the granular sludge bed reactor and microbiological mechanisms.  

PubMed

The effect of particle size on the performance of autotrophic nitrogen removal in the granular sludge bed reactor (GSB-ANR) and microbiological mechanisms were investigated. The results indicated that performance of GSB-ANR process decreased gradually with the increase of the granular sludge size. Indeed small granules ranging between 0.5 and 0.9mm had a higher nitrogen removal capacity than large ones. The reasons of this effect were that (i) the aerobic ammonium oxidizing capacity of microorganisms was the bottle neck of nitrogen removal in GSB-ANR process, and the increase of aerobic ammonium oxidizing activity enhances nitrite production in nitrification and promotes subsequent nitrite consumption during anaerobic ammonia oxidation; (ii) the aerobic/anaerobic zone separation in granular sludge was the key factor affecting the aerobic ammonium oxidizing capacity of microorganisms. The small granules had a larger aerobic functional zone (75.1%) which was profitable for up-regulating the expression level of functional gene in aerobic ammonium oxidizing microorganisms. PMID:24561629

Wang, Lan; Zheng, Ping; Xing, Yajuan; Li, Wei; Yang, Jian; Abbas, Ghulam; Liu, Shuai; He, Zhanfei; Zhang, Jiqiang; Zhang, Hongtao; Lu, Huifeng

2014-04-01

354

Nonlinear Autoregressive Exogenous modeling of a large anaerobic digester producing biogas from cattle waste.  

PubMed

In waste-to-energy plants, there is every likelihood of variations in the quantity and characteristics of the feed. Although intermediate storage tanks are used, but many times these are of inadequate capacity to dampen the variations. In such situations an anaerobic digester treating waste slurry operates under dynamic conditions. In this work a special type of dynamic Artificial Neural Network model, called Nonlinear Autoregressive Exogenous model, is used to model the dynamics of anaerobic digesters by using about one year data collected on the operating digesters. The developed model consists of two hidden layers each having 10 neurons, and uses 18days delay. There are five neurons in input layer and one neuron in output layer for a day. Model predictions of biogas production rate are close to plant performance within ±8% deviation. PMID:25151079

Dhussa, Anil K; Sambi, Surinder S; Kumar, Shashi; Kumar, Sandeep; Kumar, Surendra

2014-10-01

355

Performance evaluation of a continuous bipolar electrocoagulation/electrooxidation-electroflotation (ECEO-EF) reactor designed for simultaneous removal of ammonia and phosphate from wastewater effluent.  

PubMed

The present study aimed to evaluate the performance of a continuous bipolar ECEO-EF reactor designed for simultaneous removal of ammonia and phosphate from wastewater effluent. The reactor was comprised of two distinct units: electrochemical and separation. In the electrochemical unit, Al, stainless steel, and RuO(2)/Ti plates were used. All the measurements were performed according to the standard methods. Maximum efficiency of the reactor for phosphate removal was 99% at pH of 6, current density of 3A, detention time of 60 min, and influent phosphate concentration of 50mg/l. The corresponding value for ammonia removal was 99% at a pH of 7 under the same operational conditions as for phosphate removal. For both phosphate and ammonia, the removal efficiency was highest at neutral pH, with higher current densities, and with lower influent concentrations. In addition to removal of phosphate and ammonia, application of the Al(3+) plates enabled the removal of nitrite and nitrate, which may be present in wastewater effluent and are also products of the electrochemical process. The reactor was also able to decrease the concentrations of phosphate, ammonia, and COD under actual wastewater conditions by 98%, 98%, and 72%, respectively. According to the results of the present study, the reactor can be used for efficient removal of ammonia and phosphate from wastewater. PMID:21741172

Mahvi, Amir Hossein; Ebrahimi, Seyed Jamal Al-Din; Mesdaghinia, Alireza; Gharibi, Hamed; Sowlat, Mohammad Hossein

2011-09-15

356

Comparison of UASB and EGSB reactors performance, for treatment of raw and deoiled palm oil mill effluent (POME)  

Microsoft Academic Search

Anaerobic digestion of palm oil mill effluent (POME) and deoiled POME was investigated both in batch assays and continuous reactor experiments using up-flow anaerobic sludge blanket (UASB) and expanded granular sludge bed (EGSB) reactors. The methane potential determined from batch assays of POME and deoiled POME was 503 and 610mL-CH4\\/gVS-added, respectively. For the treatment of POME in continuously fed reactors,

Cheng Fang; Sompong O-Thong; Kanokwan Boe; Irini Angelidaki

2011-01-01

357

Hydraulic performance of pump suction inlets for emergency core cooling systems in boiling water reactors. Containment sump reliability studies. Generic task A-43  

Microsoft Academic Search

This document reports on the hydraulic performance of two representative Boiling Water Reactor (BWR) Residual Heat Removal (RHR) suction inlet configurations; namely, those of the Mark I, and Mark II and Mark III designs. Key parameters of interest were air-ingestion levels, vortex types, suction pipe swirl, and the RHR inlet pressure loss coefficient. Tests were conducted with nearly uniform and

1982-01-01

358

Cassava Stillage Treatment by Thermophilic Anaerobic Continuously Stirred Tank Reactor (CSTR)  

NASA Astrophysics Data System (ADS)

This paper assesses the performance of a thermophilic anaerobic Continuously Stirred Tank Reactor (CSTR) in the treatment of cassava stillage under various organic loading rates (OLRs) without suspended solids (SS) separation. The reactor was seeded with mesophilic anaerobic granular sludge, and the OLR increased by increments to 13.80 kg COD/m3/d (HRT 5d) over 80 days. Total COD removal efficiency remained stable at 90%, with biogas production at 18 L/d (60% methane). Increase in the OLR to 19.30 kg COD/m3/d (HRT 3d), however, led to a decrease in TCOD removal efficiency to 79% due to accumulation of suspended solids and incomplete degradation after shortened retention time. Reactor performance subsequently increased after OLR reduction. Alkalinity, VFA and pH levels were not significantly affected by OLR variation, indicating that no additional alkaline or pH adjustment is required. More than half of the SS in the cassava stillage could be digested in the process when HRT was 5 days, which demonstrated the suitability of anaerobic treatment of cassava stillage without SS separation.

Luo, Gang; Xie, Li; Zou, Zhonghai; Zhou, Qi

2010-11-01

359

5th International Landfills Conference -Sardinia'95, Cagliari, 1995 DEVELOPMENT AND VALIDATION OF A METHOD FOR MEASURING BIOGAS  

E-print Network

OF A METHOD FOR MEASURING BIOGAS EMISSIONS USING A DYNAMIC CHAMBER Zbigniew POKRYSZKA, Christian TAUZIEDE biogas flow, designing a dynamic flux chamber. Preliminary bench tests revealed the necessity of defining gas releases. A mixture of gases (known as biogas) is produced from organic waste, and consists mainly

Paris-Sud XI, Université de

360

Comparative study of economics of different models of family size biogas plants for state of Punjab, India  

Microsoft Academic Search

Biogas, the end product of anaerobic digestion of cattle dung, can successfully supplement the cooking fuels in the countryside areas of India, where the raw material needed for its production is plentifully available. Because of the lack of awareness regarding selection of a suitable model and size of biogas plant, the full potential of the biogas producing material is not

K. Jatinder Singh; Sarbjit Singh Sooch

2004-01-01

361

Environmental systems analysis of biogas systems—Part II: The environmental impact of replacing various reference systems  

Microsoft Academic Search

This paper analyses the overall environmental impact when biogas systems are introduced and replace various reference systems for energy generation, waste management and agricultural production. The analyses are based on Swedish conditions using a life-cycle perspective. The biogas systems included are based on different combinations of raw materials and final use of the biogas produced (heat, power and transportation fuel).

Pål Börjesson; Maria Berglund

2007-01-01

362

Numerical and experimental study of soot formation in laminar diffusion flames burning simulated biogas fuels at elevated pressures  

E-print Network

biogas fuels at elevated pressures Marc R.J. Charest , �mer L. Gülder, Clinton P.T. Groth University 18 April 2014 Available online 2 June 2014 Keywords: Soot formation High pressure combustion Biogas, and other chemical species that are harmful to human health and the environment. Gaseous biofuels, or biogas

Gülder, �mer L.

363

Performance demonstration of a high-power space reactor heat pipe design  

SciTech Connect

Performance of a 15.9-mm diam, 2-m long, artery heat pipe has been demonstrated at power levels to 22.6 kW and temperatures to 1500 KAPPA. The heat pipe employed lithium as a working fluid with distribution wicks and arteries fabricated from 400 mesh Mo-41 wt% Re screen. Molybdenum alloy (TZM) was used for the container. Peak axial power density attained in the testing was 19 kW/cm/sup 2/ at 1465 KAPPA. The corresponding radial flux density in the evaporator region of the heat pipe was 150 W/cm/sup 2/. The extrapolated limit for the heat pipe at its 1500 KAPPA design point is 30 kW, corresponding to an axial flux density of 25 kW/cm/sup 2/. Sonic and capillary limits for the design were investigated in the 1100 to 1500 KAPPA temperature range. Excellent agreement of measured and predicted temperature and power levels was observed.

Merrigan, M.A.; Keddy, E.S.; Kemme, J.E.; Martinez, E.H.; Runyan, J.E.

1983-08-01

364

Optimization of biogas production by anaerobic digestion for sustainable energy development in Zimbabwe  

Microsoft Academic Search

There is increasing international interest in developing low carbon renewable energy technologies. Biomass is increasingly being utilized as an energy source throughout the world. Several modern technologies have been developed that convert biomass to bioenergy. Anaerobic digestion is a mature energy technology for converting biomass to biogas, which is a renewable primary energy source. Biogas is a robust fuel that

Raphael M. Jingura; Rutendo Matengaifa

2009-01-01

365

Impact of biogas digesters on cookhouse volatile organic compound exposure for rural Kenyan farmwomen.  

PubMed

Women living on rural Kenyan smallholder dairy farms burn wood as biofuel in family cookhouses. Unventilated biofuel combustion produces harmful levels of respirable particles and volatile organic compound (VOC) emissions in indoor environments. Biogas digesters, which can generate high methane-content biogas from livestock manure composting were recently installed on 31 farms. The study objectives were to compare VOC exposure profiles for women cooking on farms with and without biogas digesters, and to compare seasonal variations in VOC exposures for those women cooking with biogas. Participants (n=31 biogas farms, n=31 referent farms) wore passive thermal desorption VOC sampling tubes and recorded cookhouse fuel use on time activity sheets for 7 days. Women using biogas spent significantly less time (mean=509?min/week) exposed to cookhouse wood smoke compared with the referent group (mean=1122?min/week) (P<0.01). Total VOC exposure did not differ between farm groups (P=0.14), though concentrations of trans-1,3-dichloropropene, bromoform, and 1,4-dichlorobenzene in biogas cookhouses were significantly lower than in referent cookhouses, even after Bonferroni correction. The composition of VOC species was also significantly different, reflecting the different fuel sources. Biogas digester technologies have great potential for reducing exposure to wood smoke VOCs in low-income countries.Journal of Exposure Science and Environmental Epidemiology advance online publication, 31 July 2013; doi:10.1038/jes.2013.42. PMID:23899962

Dohoo, Carolyn; Read Guernsey, Judith; Gibson, Mark D; VanLeeuwen, John

2013-07-31

366

Enhancement of biogas production from solid substrates using different techniques––a review  

Microsoft Academic Search

Biogas, a clean and renewable form of energy could very well substitute (especially in the rural sector) for conventional sources of energy (fossil fuels, oil, etc.) which are causing ecological–environmental problems and at the same time depleting at a faster rate. Despite its numerous advantages, the potential of biogas technology could not be fully harnessed or tapped as certain constraints

Yadvika; Santosh; T. R. Sreekrishnan; Sangeeta Kohli; Vineet Rana

2004-01-01

367

Technical and economic analysis of biogas production in Ireland utilising three different crop rotations  

Microsoft Academic Search

The Biofuels Directive sets reference values for the quantity of biofuels and other renewable fuels to be placed on the transport market. Biogas from agricultural crops can be used to meet this directive. This paper investigates biogas production for three crop rotations: wheat, barley and sugar beet; wheat, wheat and sugar beet; wheat only. A technical and economic analysis for

J. D. Murphy; N. Power

2009-01-01

368

Origin of positive ? 13C of emitted CO 2 from soils after application of biogas residues  

Microsoft Academic Search

Bioenergy production from renewable organic material is known to be a clean energy source and therefore its use is currently much promoted in many countries. Biogas by-products also called biogas residues (BGR) are rich in partially stable organic carbon and can be used as an organic fertilizer for crop production. However so far, many environmental issues relevant when BGR are

Ruirui Chen; Mehmet Senbayram; Xiangui Lin; Klaus Dittert

2011-01-01

369

Effect of temperature and retention period on biogas production from lignocellulosic material  

Microsoft Academic Search

The extensive utilization of biogas for energy needs of rural dwellers would reduce their dependence on fossil fuels and fuelwoods and henoe camplement Government afforestation programes. In this investigation, effect of temperature and retention period on biogas production from lignooellulosic material, hereafter referred to as cow dung were studied. Maximum gas production was dotained at thermophilic temperature. The results of

B. Garba

1996-01-01

370

Effect of continuous Cd feeding on the performance of a nitrification reactor.  

PubMed

The inhibitory effect of Cd on nitrification was investigated in a continuous-flow system with enriched nitrifying bacteria. The maximum specific ammonium utilization rate and the half-saturation constant were found as 671 mg NH(4)-N/g VSS day and 0.48 mg/l, respectively. In the case of continuous Cd input at 1 and 2.5 mg/l, nitrification was inhibited by 30% and 47%, respectively. Inhibition ranged from 20% to 40% and no further increase in inhibition was exhibited in new runs except at 10 mg/l influent Cd. At 10 mg/l influent Cd, specific ammonium utilization and nitrate production rates were inhibited by 90%. On the contrary, a serious nitrite accumulation was not observed during this period. When Cd feeding was stopped, recovery from inhibition was observed after 37 day which was seen by the improvement in ammonium utilization and nitrate production rates. A shift in microbial population from the initial Nitrosomonas sp. to the Cd-tolerant Nitrosospira sp. was observed in the recovery period from severe Cd inhibition. After the domination of Nitrosospira species, redosing at 10 mg/l and then at 15 mg/l did not affect the performance as before. PMID:18677441

Semerci, Neslihan; Ceçen, Ferhan

2009-04-01

371

Performance demonstration of a high-power space-reactor heat-pipe design  

SciTech Connect

Performance of a 15.9-mm diam, 2-m long, artery heat pipe has been demonstrated at power levels to 22.6 kW and temperatures to 1500/sup 0/K. The heat pipe employed lithium as a working fluid with distribution wicks and arteries fabricated from 400 mesh Mo-41 wt % Re screen. Molybdenum alloy (TZM) was used for the container. Peak axial power density attained in the testing was 19 kW/cm/sup 2/ at 1465/sup 0/K. The corresponding radial flux density in the evaporator region of the heat pipe was 150 W/cm/sup 2/. The extrapolated limit for the heat pipe at its 1500/sup 0/K design point is 30 kW, corresponding to an axial flux density of 25 kW/cm/sup 2/. Sonic and capillary limits for the design were investigated in the 1100 to 1500/sup 0/K temperature range. Excellent agreement of measured and predicted temperature and power levels was observed.

Merrigan, M.A.; Martinez, E.H.; Keddy, E.S.; Runyan, J.; Kemme, J.E.

1983-01-01

372

TOKOPS: Tokamak Reactor Operations Study: The influence of reactor operations on the design and performance of tokamaks with solid-breeder blankets: Final report  

SciTech Connect

Reactor system operation and procedures have a profound impact on the conception and design of power plants. These issues are studied here using a model tokamak system employing a solid-breeder blanket. The model blanket is one which has evolved from the STARFIRE and BCSS studies. The reactor parameters are similar to those characterizing near-term fusion engineering reactors such as INTOR or NET (Next European Tokamak). Plasma startup, burn analysis, and methods for operation at various levels of output power are studied. A critical, and complicating, element is found to be the self-consistent electromagnetic response of the system, including the presence of the blanket and the resulting forces and loadings. Fractional power operation, and the strategy for burn control, is found to vary depending on the scaling law for energy confinement, and an extensive study is reported. Full-power reactor operation is at a neutron wall loading pf 5 MW/m/sup 2/ and a surface heat flux of 1 MW/m/sup 2/. The blanket is a pressurized steel module with bare beryllium rods and low-activation HT-9-(9-C-) clad LiAlO/sub 2/ rods. The helium coolant pressure is 5 MPa, entering the module at 297/sup 0/C and exiting at 550/sup 0/C. The system power output is rated at 1000 MW(e). In this report, we present our findings on various operational scenarios and their impact on system design. We first start with the salient aspects of operational physics. Time-dependent analyses of the blanket and balance of plant are then presented. Separate abstracts are included for each chapter.

Conn, R.W.; Ghoniem, N.M.; Firestone, M.A. (eds.)

1986-09-01

373

Nonrenewable Energy Cost and Greenhouse Gas Emissions of a “Pig-Biogas-Fish” System in China  

PubMed Central

The purpose of this study is to assess the energy savings and emission reductions of the present rural biogas system in China. The life cycle assessment (LCA) method is used to analyze a “pig-biogas-fish” system in Jingzhou, Hubei Province, China. The nonrenewable energy cost and the greenhouse gas (GHG) emissions of the system, including the pigsty, the biogas digester, and the fishpond, are taken into account. The border definition is standardized because of the utilization of the database in this paper. The results indicate that the nonrenewable energy consumption intensity of the “pig-biogas-fish” system is 0.60?MJ/MJ and the equivalent CO2 emission intensity is 0.05?kg CO2-eq/MJ. Compared with the conventional animal husbandry system, the “pig-biogas-fish” system shows high renewability and GHG reduction benefit, which indicates that the system is a scientific and environmentally friendly chain combining energy and ecology. PMID:23213302

Yang, Qing; Wu, Xiaofang; Yang, Haiping; Zhang, Shihong; Chen, Hanping

2012-01-01

374

Pilot-scale field study for ammonia removal from lagoon biogas using an acid wet scrubber.  

PubMed

The anaerobic activities in swine slurry storage and treatment generate biogas containing gaseous ammonia component which is a chemical agent that can cause adverse environmental impacts when released to the atmosphere. The aim of this pilot plant study was to remove ammonia from biogas generated in a covered lagoon, using a sulfuric acid wet scrubber. The data showed that, on average, the biogas contained 43.7 ppm of ammonia and its concentration was found to be exponentially related to the air temperature inside the lagoon. When the air temperature rose to 35°C and the biogas ammonia concentration reached 90 ppm, the mass transfer of ammonia/ammonium from the deeper liquid body to the interface between the air and liquid became a limiting factor. The biogas velocity was critical in affecting ammonia removal efficiency of the wet scrubber. A biogas flow velocity of 8 to 12 mm s(-1) was recommended to achieve a removal efficiency of greater than 60%. Stepwise regression revealed that the biogas velocity and air temperature, not the inlet ammonia concentration in biogas, affected the ammonia removal efficiency. Overall, when 73 g L(-1) (or 0.75 M) sulfuric acid solution was used as the scrubber solution, removal efficiencies varied from 0% to 100% with an average of 55% over a 40-d measurement period. Mass balance calculation based on ammonium-nitrogen concentration in final scrubber liquid showed that about 21.3 g of ammonia was collected from a total volume of 1169 m(3) of biogas, while the scrubber solution should still maintain its ammonia absorbing ability until its concentration reaches up to 1 M. These results showed promising use of sulfuric acid wet scrubber for ammonia removal in the digester biogas. PMID:24762182

Lin, Hongjian; Wu, Xiao; Miller, Curtis; Zhu, Jun; Hadlocon, Lara Jane; Manuzon, Roderick; Zhao, Lingying

2014-06-01

375

A comprehensive model of anaerobic bioconversion of complex substrates to biogas  

SciTech Connect

A dynamic model describing the anaerobic degradation of complex material, and codigestion of different types of wastes, was developed based on a model previously described. In the model, the substrate is described by its composition of basic organic components, i.e., carbohydrates, lipids, and proteins, the concentration of intermediates such as volatile fatty acids and long-chain fatty acids, and important inorganic components, i.e., ammonia, phosphate, cations, and anions. This allows dynamic changes of the process during a shift of substrate composition to be simulated by changing the input substrate data. The model includes 2 enzymatic hydrolytic steps, 8 bacterial steps and involves 19 chemical compounds. The model also includes a detailed description of pH and temperature characteristics. Free ammonia, acetate, volatile fatty acids, (VFA) and long-chain fatty acids (LCFA) constitute the primary modulating factors in the model. The model was tested with success in lab-scale reactors codigesting manure with glycerol trioleate or manure with gelatin. Finally, the model was validated using results from a full-scale biogas plant codigesting manure together with a proteinous wastewater and with bentonite-bound oil, which is a waste with high content of lipids.

Angelidaki, I.; Ellegaard, L.; Ahring, B.K. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Biotechnology] [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Biotechnology

1999-05-05

376

Searching for links in the biotic characteristics and abiotic parameters of nine different biogas plants  

PubMed Central

Summary To find links between the biotic characteristics and abiotic process parameters in anaerobic digestion systems, the microbial communities of nine full?scale biogas plants in South Tyrol (Italy) and Vorarlberg (Austria) were investigated using molecular techniques and the physical and chemical properties were monitored. DNA from sludge samples was subjected to microarray hybridization with the ANAEROCHIP microarray and results indicated that sludge samples grouped into two main clusters, dominated either by Methanosarcina or by Methanosaeta, both aceticlastic methanogens. Hydrogenotrophic methanogens were hardly detected or if detected, gave low hybridization signals. Results obtained using denaturing gradient gel electrophoresis (DGGE) supported the findings of microarray hybridization. Real?time PCR targeting Methanosarcina and Methanosaeta was conducted to provide quantitative data on the dominating methanogens. Correlation analysis to determine any links between the microbial communities found by microarray analysis, and the physicochemical parameters investigated was conducted. It was shown that the sludge samples dominated by the genus Methanosarcina were positively correlated with higher concentrations of acetate, whereas sludge samples dominated by representatives of the genus Methanosaeta had lower acetate concentrations. No other correlations between biotic characteristics and abiotic parameters were found. Methanogenic communities in each reactor were highly stable and resilient over the whole year. PMID:22950603

Walter, Andreas; Knapp, Brigitte A.; Farbmacher, Theresa; Ebner, Christian; Insam, Heribert; Franke?Whittle, Ingrid H.

2012-01-01

377

Deployment of a Suite of High-Performance Computational Tools for Multi-scale Multi-physics Simulation of Generation IV Reactors  

SciTech Connect

The overall objective of this project has been to deploy advanced simulation capabilities for next generation reactor systems utilizing newly available, high-performance computing facilities. The approach includes the following major components: The development of new simulation capabilities using state-of-the-art computer codes of different scales: molecular dynamics (MD) level, DNS (FronTier and PHASTA) and CFD (NPHASE-CMFD); The development of advanced numerical solvers for large-size computational problems; The deployment of a multiple-code computational platform for multiscale simulations of gas/liquid two-phase flow during reactor transients and accidents; and Application of the new computational methodology to study the progression of loss-of-flow accident in sodium fast reactor (SFR).

Michael Z. Podowski

2013-01-03

378

Siloxanes removal from biogas by high surface area adsorbents.  

PubMed

Biogas utilized for energy production needs to be free from organic silicon compounds, as their burning has damaging effects on turbines and engines; organic silicon compounds in the form of siloxanes can be found in biogas produced from urban wastes, due to their massive industrial use in synthetic product, such as cosmetics, detergents and paints. Siloxanes removal from biogas can be carried out by various methods (Mona, 2009; Ajhar et al., 2010 May; Schweigkofler and Niessner, 2001); aim of the present work is to find a single practical and economic way to drastically and simultaneously reduce both the hydrogen sulphide and the siloxanes concentration to less than 1 ppm. Some commercial activated carbons previously selected (Monteleone et al., 2011) as being effective in hydrogen sulfide up taking have been tested in an adsorption measurement apparatus, by flowing the most volatile siloxane (hexamethyldisiloxane or L2) in a nitrogen stream, typically 100-200 ppm L2 over N2, through an activated carbon powder bed; the adsorption process was analyzed by varying some experimental parameters (concentration, grain size, bed height). The best activated carbon shows an adsorption capacity of 0.1g L2 per gram of carbon. The next thermogravimetric analysis (TGA) confirms the capacity data obtained experimentally by the breakthrough curve tests. The capacity results depend on L2 concentration. A regenerative carbon process is then carried out by heating the carbon bed up to 200 °C and flushing out the adsorbed L2 samples in a nitrogen stream in a three step heating procedure up to 200 °C. The adsorption capacity is observed to degrade after cycling the samples through several adsorption-desorption cycles. PMID:24075968

Gislon, P; Galli, S; Monteleone, G

2013-12-01

379

Chinese Biogas Digester. A Potential Model for Small-Scale, Rural Applications. (A Manual for Construction and Operation). Reprint No. R-51.  

ERIC Educational Resources Information Center

This book provides the basic knowledge and guides for the construction and operation of a small-scale, family-size biogas unit. The first chapter discusses the benefits of biogas production and the Chinese biogas model. The second chapter shows the components, design formulas, and sizing units of the biogas model. Chapter 3 describes actual…

Nakagawa, Charles H.; Honquilada, Q. L.

380

Postgraduate Programme Renewable Energy (PPRE) --Biogas Workshop --01. -04. Feb. 2010 --Oldenburg University --venue: TGO, Marie-Curie-Strae 1, 26129 Oldenburg Programme Part 1  

E-print Network

Postgraduate Programme Renewable Energy (PPRE) -- Biogas Workshop -- 01. - 04. Feb. 2010 -- Oldenburg University -- venue: TGO, Marie-Curie-Stra�e 1, 26129 Oldenburg Programme Part 1: Domestic Biogas Biogas ­ Introduction: Relevance of biogas for Development (JL) 09:45 Coffee Break 10:00 From Waste

Damm, Werner

381

[Characteristics of operational performance and membrane fouling in a sidestream membrane sequencing batch reactor with aerobic granule].  

PubMed

The characteristics of operational performance and membrane fouling were investigated using synthetic wastewater as feed in a sidestream membrane sequencing batch reactor (MSBR) system. The experimental results showed that the average removal efficiencies of COD, TN, TP and NH4+ -N were 90%, 60%-80%, 80% and 95% respectively under the influent COD of 200 mg x L(-1) to 1200 mg x L(-1) during more than 150 days' operation. It was possible to achieve a complete granulation of sludge. In 70th day, sludge particles around 350 microm were detected more than 90%. From then, sludge grew up continuously and finally reached to 394 microm in diameter. With the formation of granular sludge in MSBR, the cleaning time of membrane system was prolonged to 65 days, which was larger than three times compared with flocculent sludge MSBR. It was also much better than conventional MBR. These results clearly demonstrated that the formation of granular sludge was good for improving the resistance to organic loading shock and retaining the membrane fouling of the system, and maintaining the stable operation for a long time. PMID:20358838

Xu, Li-rong; Huang, Dan; Li, Xiao-ning; Zhu, Jian-rong

2010-03-01

382

Recycled paper mill effluent treatment in a modified anaerobic baffled reactor: start-up and steady-state performance.  

PubMed

Start-up period is considered to be the most unstable and difficult stage in anaerobic process and usually takes a long time due to slow-degree adaptation of anaerobic microorganisms. In order to achieve a shorter start-up period, a novel modified anaerobic baffled reactor (MABR) has been developed in this study, where each modified baffle has its own characteristics (form/shape) to facilitate a treatment ofrecycled paper mill effluent (RPME). The results ofphysico-chemical characteristics showed that effluent from recycled paper mill consisted of 4328mgL-1 chemical oxygen demand (COD), 669mg L-1 biochemical oxygen demand and 501mg L-1 volatile fatty acid. It also consisted of variety of heavy metals such as zinc, magnesium, iron and nickel at concentrations of 1.39, 12.19, 2.39 and 0.72 mgL-1, respectively. Performance of MABR during the start-up period showed that methane production reached 34.7% with COD removal of 85% at steady state. The result indicates that MABR was successfully operated during the start-up period in treating RPME within a period of less than 30 days. PMID:24600868

Hassana, Siti Roshayu; Zwaina, Haider M; Zamana, Nastaein Qamaruz; Dahlanb, Irvan

2014-01-01

383

Influence of the C/N ratio on the performance of polyhydroxybutyrate (PHB) producing sequencing batch reactors at short SRTs.  

PubMed

Many waste streams that are suitable substrates for mixed culture bioplastic (polyhydroxyalkanoate, PHA) production are nutrient limited and may need to be supplemented to allow sufficient growth of PHA accumulating bacteria. The scope of this study was to investigate the necessity of nutrient supplementation for the enrichment of an efficient PHA producing mixed culture. We studied the influence of different degrees of carbon and nitrogen limitation on the performance of an acetate-fed feast-famine sequencing batch reactor (SBR) employed to enrich PHA storing bacteria. The microbial reaction rates in the SBR showed a shift with a change in the limiting substrate: high acetate uptake rates were found in carbon-limited SBRs (medium C/N ratios 6-13.2 Cmol/Nmol), while nitrogen-limited SBRs (medium C/N ratios 15-24 Cmol/Nmol) were characterized by high ammonia uptake rates. Biomass in strongly nitrogen-limited SBRs had higher baseline PHA contents in the SBR, but carbon-limited SBRs resulted usually in biomass with higher maximal PHA storage capacities. The PHA storage capacity in a nitrogen-limited SBR operated at 0.5 d SRT decreased significantly over less than 5 months operation. For the microbial selection and biomass production stage of a PHA production process carbon limitation seems thus favourable and nutrient deficient wastewaters may consequently require supplementation with nutrients for the selection of a stable PHA storing biomass with a high storage capacity. PMID:20189213

Johnson, Katja; Kleerebezem, Robbert; van Loosdrecht, Mark C M

2010-04-01

384

Aerobic methane oxidation coupled to denitrification in a membrane biofilm reactor: treatment performance and the effect of oxygen ventilation.  

PubMed

Aerobic methane-oxidation coupled to denitrification (AME-D) process was successfully achieved in a membrane biofilm reactor (MBfR). PVDF membrane was employed to supply the methane and oxygen for biofilm, which was coexistence of methanotrophs and denitrifier. With a feeding NO3(-)-N of 30 mg/L, up to 97% nitrate could be removed stably. The oxygen ventilation modes impacted the denitrification performance remarkably, resulting in different nitrate removal efficiencies and biofilm microorganism distribution. The biofilm sludge showed a high resistance to the DO inhibition, mainly due to the co-existing methanotroph being capable of utilizing oxygen perferentially within biofilm, and create an anoxic micro-environment. The denitrification of both nitrate and nitrite by biofilm sludge conformed to the Monod equation, and the maximum specific nitrate utilization rate (k) ranged from 1.55 to 1.78 NO3(-)-N/g VSS-d. The research findings should be significant to understand the considerable potential of MBfR as a bioprocess for denitrification. PMID:23582221

Sun, Fei-yun; Dong, Wen-yi; Shao, Ming-fei; Lv, Xiao-mei; Li, Ji; Peng, Liang-yu; Wang, Hong-jie

2013-10-01

385

On-farm biogas systems information dissemination project. Final report  

SciTech Connect

The purpose of this project was to study how farmers manage anaerobic digesters on three New York State dairy farms. Two years of data collected were from both plug-flow and tower-type mixed-flow digesters at regular intervals over a three-year period revealed that the financial return from the energy produced by a biogass system in the late 1980`s is marginal. Little difficulty was experienced in operation of the anaerobic digester; however, several farms utilizing congeneration to convert biogas into electricity and heat suffered from not applying maintenance to the congenerator in a timely fashion.

Campbell, J.K.; Koelsch, R.K.; Guest, R.W.; Fabian, E.

1997-03-01

386

Improvement of biogas production from vinasse via covalently immobilized methanogens.  

PubMed

Improvement of biogas production was realized by covalent immobilization of a methanogenic consortium onto a granulated polymeric support [poly(acrylonitrile-acrylamide)]. The growth kinetics of the immobilized consortium was investigated during a process of vinasse methanation, and a cell concentration increase from 12.3 mg g(-1) support to 52.1 mg g(-1) support was established. The methane yield reached 0.33 m3 kg(-1) CODr, the maximum yield on chemical oxygen demand (COD) removal being 92%. The inhibitory effect of oxygen was reduced by immobilizing the methanogenic consortium. PMID:11396912

Lalov, I G; Krysteva, M A; Phelouzat, J L

2001-08-01

387

Biogas-Fired Internal Combustion Engine Combined  

E-print Network

Verification (ETV) program to facilitate the deployment of innovative or improved environmental technologies through performance verification and dissemination of information. The goal of the ETV program is to further environmental protection by accelerating the acceptance and use of improved and cost-effective technologies. ETV seeks to achieve this goal by providing high-quality, peer-reviewed data on technology performance to those involved in the purchase, design, distribution, financing, permitting, and use of environmental technologies. ETV works in partnership with recognized standards and testing organizations, stakeholder groups that consist of buyers, vendor organizations, and permitters, and with the full participation of individual technology developers. The program evaluates the performance of technologies by developing test plans that are responsive to the needs of stakeholders, conducting field or laboratory tests, collecting and analyzing data, and preparing peer-reviewed reports. All evaluations are conducted in accordance with rigorous quality assurance protocols to ensure that data of known and adequate quality are generated and that the results are defensible. The Greenhouse Gas Technology Center (GHG Center), one of six verification organizations under the

unknown authors

2004-01-01

388

Performance of aerated submerged biofilm reactor packed with local scoria for carbon and nitrogen removal from municipal wastewater.  

PubMed

An up-flow submerged biofilm reactor packed with scoria was evaluated for municipal wastewater treatment. The reactor was operated two cycles (with and without effluent recycle) as single aerobic reactor at hydraulic loading rate (HLR) of 3.5-4.0 L/L/day and four cycles (with and without effluent recycle) as anaerobic/aerobic reactor at two HLR (3.5 and 5.2 L/L/day). Results indicated better removal efficiency in case of anaerobic/aerobic cycles especially for ammonia and total nitrogen. Effluent recycling in the aerobic reactor enhanced ammonification with significant reduction in ammonia and nitrogen removal, while in case of single anaerobic/aerobic reactor the effluent recycling improved ammonia and nitrogen removal and kept nitrate concentration in the final effluent below 10 mg N/L. The reactor produced good settled sludge with sludge volume index (SVI) of 46-74 ml/g for aerobic cycles and 18-50 ml/g for anaerobic/aerobic cycles. The average sludge production was 0.145 g TSS/g COD removed. PMID:23831746

El-Shafai, Saber A; Zahid, Waleed M

2013-09-01

389

Towards molecular biomarkers for biogas production from lignocellulose-rich substrates.  

PubMed

Biogas production from lignocellulose-rich agricultural residues is gaining increasingly importance in sustainable energy production. Hydrolysis/acidogenesis (H/A) of lignocellulose as the initial rate-limiting step deserves particular optimization. A mixture of straw/hay was methanized applying two-phase digester systems with an initial H/A reactor and a one-stage system at different, meso- and thermophilic temperatures. H/A was intensified with increasing pH values and increasing temperature. H/A fermenters, however, were prone to switch to methanogenic systems at these conditions. Substrate turnover was accelerated in the bi-phasic process but did not reach the methanation efficiency of the single-stage digestion. There was no indication that two different cellulolytic inocula could establish in the given process. Bacterial communities were analyzed applying conventional amplicon clone sequencing targeting the hypervariable 16S rRNA gene region V6-V8 and by metagenome analyses applying direct DNA pyrosequencing without a PCR step. Corresponding results suggested that PCR did not introduce a bias but offered better phylogenetic resolution. Certain Clostridium IV and Prevotella members were most abundant in the H/A system operated at 38 °C, certain Clostridium III and Lachnospiraceae bacteria in the 45 °C, and certain Clostridium IV and Thermohydrogenium/Thermoanaerobacterium members in the 55 °C H/A system. Clostridium III representatives, Lachnospiraceae and Thermotogae dominated in the thermophilic single-stage system, in which also a higher portion of known syntrophic acetate oxidizers was found. Specific (RT-)qPCR systems were designed and applied for the most significant and abundant populations to assess their activity in the different digestion systems. The RT-qPCR results agreed with the DNA based community profiles obtained at the different temperatures. Up to 10(12) 16S rRNA copies mL(-1) were determined in H/A fermenters with prevalence of rRNA of a Ruminococcaceae subgroup. Besides, Thermohydrogenium/Thermoanaerobacterium rRNA prevailed at thermophilic and Prevotellaceae rRNA at mesophilic conditions. The developed (RT)-qPCR systems can be used as biomarkers to optimize biogas production from straw/hay and possibly other lignocellulosic substrates. PMID:24785351

Lebuhn, Michael; Hanreich, Angelika; Klocke, Michael; Schlüter, Andreas; Bauer, Christoph; Pérez, Carmen Marín

2014-10-01

390

Controlled continuous bio-hydrogen production using different biogas release strategies.  

PubMed

Dark fermentation for bio-hydrogen (bio-H2) production is an easily operated and environmentally friendly technology. However, low bio-H2 production yield has been reported as its main drawback. Two strategies have been followed in the past to improve this fact: genetic modifications and adjusting the reaction conditions. In this paper, the second one is followed to regulate the bio-H2 release from the reactor. This operating condition alters the metabolic pathways and increased the bio-H2 production twice. Gas release was forced in the continuous culture to study the equilibrium in the mass transfer between the gaseous and liquid phases. This equilibrium depends on the H2, CO2, and volatile fatty acids production. The effect of reducing the bio-H2 partial pressure (bio-H2?pp) to enhance bio-H2 production was evaluated in a 30 L continuous stirred tank reactor. Three bio-H2 release strategies were followed: uncontrolled, intermittent, and constant. In the so called uncontrolled fermentation, without bio-H2?pp control, a bio-H2 molar yield of 1.2 mol/mol glucose was obtained. A sustained low bio-H2?pp of 0.06 atm increased the bio-H2 production rate from 16.1 to 108 mL/L/h with a stable bio-H2 percentage of 55% (v/v) and a molar yield of 1.9 mol/mol glucose. Biogas release enhanced bio-H2 production because lower bio-H2 pp, CO2 concentration, and reduced volatile fatty acids accumulation prevented the associated inhibitions and bio-H2 consumption. PMID:24879593

Esquivel-Elizondo, S; Chairez, I; Salgado, E; Aranda, J S; Baquerizo, G; Garcia-Peña, E I

2014-08-01

391

The performance enhancements of upflow anaerobic sludge blanket (UASB) reactors for domestic sludge treatment--a state-of-the-art review.  

PubMed

Nowadays, carbon emission and therefore carbon footprint of water utilities is an important issue. In this respect, we should consider the opportunities to reduce carbon footprint for small and large wastewater treatment plants. The use of anaerobic rather than aerobic treatment processes would achieve this aim because no aeration is required and the generation of methane can be used within the plant. High-rate anaerobic digesters receive great interests due to their high loading capacity and low sludge production. Among them, the upflow anaerobic sludge blanket (UASB) reactors have been most widely used. However, there are still unresolved issues inhibiting the widespread of this technology in developing countries or countries with climate temperature fluctuations (such as subtropical regions). A large number of studies have been carried out in order to enhance the performance of UASB reactors but there is a lack of updated documentation. In face of the existing limitations and the increasing importance of this technology, the authors present an up-to-date review on the performance enhancements of UASB reactors over the last decade. The important aspects of this article are: (i) enhancing the start-up and granulation in UASB reactors, (ii) coupling with post-treatment unit to overcome the temperature constraint, and (iii) improving the removal efficiencies of the organic matter, nutrients and pathogens in the final effluent. Finally the authors have highlighted future research direction based on their critical analysis. PMID:22560620

Chong, Siewhui; Sen, Tushar Kanti; Kayaalp, Ahmet; Ang, Ha Ming

2012-07-01

392

Impact of ozone pre-treatment on the performance of upflow anaerobic sludge blanket treating pre-treated grain distillery wastewater.  

PubMed

Two 2 L laboratory-scale upflow anaerobic sludge blanket (UASB) reactors were operated for 277 days. The substrate of the control reactor (Rc) contained grain distillery wastewater (GDWW) that had undergone coagulant pre-treatment, and the substrate of the second UASB reactor consisted of GDWW that had undergone coagulant pre-treatment and ozone pre-treatment (Ro). Both reactors treated pre-treated GDWW successfully at ca. 9 kgCOD m(-3) d(-1). Chemical oxygen demand (COD) reductions of ca. 96% for Rc and 93% for Ro were achieved. Fats, oils and grease (FOG) reductions (%) showed variations throughout the study, and reductions of ca. 88 and 92% were achieved for Rc and Ro, respectively. Rc produced more biogas, and the methane percentage was similar in both reactors. UASB granule washout in Rc suggested possible toxicity of unsaturated fatty acids present in non-ozonated substrate. The feasibility of FOG removal was demonstrated as both reactors successfully treated pre-treated GDWW. Better results were obtained for Ro effluent during post-ozonation. The ozone pre-treatment possibly led to easier degradable wastewater, and better results could potentially be obtained when other post-treatment steps are applied. Ozone pre-treatment did not, however, show an added benefit in the reactor performance results. PMID:25429461

Robertson, L; Britz, T J; Sigge, G O

2014-01-01

393

Single-phase and two-phase anaerobic digestion of fruit and vegetable waste: comparison of start-up, reactor stability and process performance.  

PubMed

Single-phase and two-phase digestion of fruit and vegetable waste were studied to compare reactor start-up, reactor stability and performance (methane yield, volatile solids reduction and energy yield). The single-phase reactor (SPR) was a conventional reactor operated at a low loading rate (maximum of 3.5 kgVS/m3 d), while the two-phase system consisted of an acidification reactor (TPAR) and a methanogenic reactor (TPMR). The TPAR was inoculated with methanogenic sludge similar to the SPR, but was operated with step-wise increase in the loading rate and with total recirculation of reactor solids to convert it into acidification sludge. Before each feeding, part of the sludge from TPAR was centrifuged, the centrifuge liquid (solubilized products) was fed to the TPMR and centrifuged solids were recycled back to the reactor. Single-phase digestion produced a methane yield of 0.45 m3 CH4/kg VS fed and VS removal of 83%. The TPAR shifted to acidification mode at an OLR of 10.0 kgVS/m3 d and then achieved stable performance at 7.0 kgVS/m3 d and pH 5.5-6.2, with very high substrate solubilization rate and a methane yield of 0.30 m3 CH4/kg COD fed. The two-phase process was capable of high VS reduction, but material and energy balance showed that the single-phase process was superior in terms of volumetric methane production and energy yield by 33%. The lower energy yield of the two-phase system was due to the loss of energy during hydrolysis in the TPAR and the deficit in methane production in the TPMR attributed to COD loss due to biomass synthesis and adsorption of hard COD onto the flocs. These results including the complicated operational procedure of the two-phase process and the economic factors suggested that the single-phase process could be the preferred system for FVW. PMID:24679584

Ganesh, Rangaraj; Torrijos, Michel; Sousbie, Philippe; Lugardon, Aurelien; Steyer, Jean Philippe; Delgenes, Jean Philippe

2014-05-01

394

Production of nitrous oxide from anaerobic digester centrate and its use as a co-oxidant of biogas to enhance energy recovery.  

PubMed

Coupled Aerobic-anoxic Nitrous Decomposition Operation (CANDO) is a new process for wastewater treatment that removes nitrogen from wastewater and recovers energy from the nitrogen in three steps: (1) NH4(+) oxidation to NO2(-); (2) NO2(-) reduction to N2O gas; and (3) N2O conversion to N2 with energy production. In this work, we optimize Steps 1 and 2 for anaerobic digester centrate, and we evaluate Step 3 for a full-scale biogas-fed internal combustion engine. Using a continuous stirred reactor coupled to a bench-scale sequencing batch reactor, we observed sustained partial oxidation of NH4(+) to NO2(-) and sustained (3 months) partial reduction of NO2(-) to N2O (75-80% conversion, mass basis), with >95% nitrogen removal (Step 2). Alternating pulses of acetate and NO2(-) selected for Comamonas (38%), Ciceribacter (16%), and Clostridium (11%). Some species stored polyhydroxybutyrate (PHB) and coupled oxidation of PHB to reduction of NO2(-) to N2O. Some species also stored phosphorus as polyphosphate granules. Injections of N2O into a biogas-fed engine at flow rates simulating a full-scale system increased power output by 5.7-7.3%. The results underscore the need for more detailed assessment of bioreactor community ecology and justify pilot- and full-scale testing. PMID:24780056

Scherson, Yaniv D; Woo, Sung-Geun; Criddle, Craig S

2014-05-20

395

Co-production of ethanol, biogas, protein fodder and natural fertilizer in organic farming--evaluation of a concept for a farm-scale biorefinery.  

PubMed

The addition of a biorefinery to an organic farm was investigated, where ethanol was produced from germinated rye grains and whey, and the effluent was separated into two streams: the protein-rich solid fraction, to be used as animal feed, and the liquid fraction, which can be co-digested with clover grass silage to produce biogas. A method for ethanol production from rye was applied by utilizing inherent amylase activity from germination of the seed. Biogas potential of ethanol fermentation effluent was measured through anaerobic digestion trials. The effluent from the trials was assumed to serve as natural fertilizer. A technoeconomic analysis was also performed; total capital investment was estimated to be approximately 4 M USD. Setting a methane selling price according to available incentives for "green electricity" (0.72 USD/m(3)) led to a minimum ethanol selling price of 1.89 USD/L (project lifetime 25 yr, at a discount rate 10%). PMID:22154299

Oleskowicz-Popiel, Piotr; Kádár, Zsófia; Heiske, Stefan; Klein-Marcuschamer, Daniel; Simmons, Blake A; Blanch, Harvey W; Schmidt, Jens Ejbye

2012-01-01

396

Biogas energy production from tropical biomass wastes by anaerobic digestion.  

PubMed

Anaerobic digestion (AD) is an attractive technology in tropical regions for converting locally abundant biomass wastes into biogas which can be used to produce heat, electricity, and transportation fuels. However, investigations on AD of tropical forestry wastes, such as albizia biomass and food wastes, such as taro, papaya, and sweet potato, are limited. In this study, these tropical biomass wastes were evaluated for biogas production by liquid AD (L-AD) and/or solid-state AD (SS-AD), depending on feedstock characteristics. When albizia leaves and chips were used as feedstocks, L-AD had greater methane yields (161 and 113 L kg(-1)VS, respectively) than SS-AD (156.8 and 59.6 L kg(-1)VS, respectively), while SS-AD achieved 5-fold higher volumetric methane productivity than L-AD. Mono-digestion and co-digestion of taro skin, taro flesh, papaya, and sweet potato achieved methane yields from 345 to 411 L kg(-1)VS, indicating the robustness of AD technology. PMID:25022835

Ge, Xumeng; Matsumoto, Tracie; Keith, Lisa; Li, Yebo

2014-10-01

397

Integrated fuel performance and thermal-hydraulic sub-channel models for analysis of sodium fast reactors  

E-print Network

Sodium Fast Reactors (SFR) show promise as an effective way to produce clean safe nuclear power while properly managing the fuel cycle. Accurate computer modeling is an important step in the design and eventual licensing ...

Fricano, Joseph William

2012-01-01

398

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

PubMed

The impact of co-digestion as opposed to separate digestion, on biogas and methane yield (apparent synergetic effects) was investigated for three biomass materials (pig manure, cow manure and food waste) under mesophilic conditions over a 36 day period. In addition to the three biomass materials (digested separately), 13 biomass mixtures (co-digested) were used. Two approaches for modelling biogas and methane yield during co-digestion, based on volatile solids concentration and ultimate gas and methane potentials, were evaluated. The dependency of apparent synergetic effects on digestion time and biomass mixture composition was further assessed using measured cumulative biogas and methane yields and specific biogas and methane generation rates. Results indicated that it is possible, based on known volatile solids concentration and ultimate biogas or methane yields for a set of biomass materials digested separately, to accurately estimate gas yields for biomass mixtures made from these materials using calibrated models. For the biomass materials considered here, modelling indicated that the addition of pig manure is the main cause of synergetic effects. Co-digestion generally resulted in improved ultimate biogas and methane yields compared to separate digestion. Biogas and methane production was furthermore significantly higher early (0-7 days) and to some degree also late (above 20 days) in the digestion process during co-digestion. PMID:25492719

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

2015-01-01

399

Investigation of the Performance of D2O-Cooled High-Conversion Reactors for Fuel Cycle Calculations  

SciTech Connect

This report presents FY13 activities for the analysis of D2O cooled tight-pitch High-Conversion PWRs (HCPWRs) with U-Pu and Th-U fueled cores aiming at break-even or near breeder conditions while retaining the negative void reactivity. The analyses are carried out from several aspects which could not be covered in FY12 activities. SCALE 6.1 code system is utilized, and a series of simple 3D fuel pin-cell models are developed in order to perform Monte Carlo based criticality and burnup calculations. The performance of U-Pu fueled cores with axial and internal blankets is analyzed in terms of their impact on the relative fissile Pu mass balance, initial Pu enrichment, and void coefficient. In FY12, Pu conversion performances of D2O-cooled HCPWRs fueled with MOX were evaluated with small sized axial/internal DU blankets (approximately 4cm of axial length) in order to ensure the negative void reactivity, which evidently limits the conversion performance of HCPWRs. In this fiscal year report, the axial sizes of DU blankets are extended up to 30 cm in order to evaluate the amount of DU necessary to reach break-even and/or breeding conditions. Several attempts are made in order to attain the milestone of the HCPWR designs (i.e., break-even condition and negative void reactivity) by modeling of HCPWRs under different conditions such as boiling of D2O coolant, MOX with different 235U enrichment, and different target burnups. A similar set of analyses are performed for Th-U fueled cores. Several promising characteristics of 233U over other fissile like 239Pu and 235U, most notably its higher fission neutrons per absorption in thermal and epithermal ranges combined with lower ___ in the fast range than 239Pu allows Th-U cores to be taller than MOX ones. Such an advantage results in 4% higher relative fissile mass balance than that of U-Pu fueled cores while retaining the negative void reactivity until the target burnup of 51 GWd/t. Several other distinctions between U-Pu and Th-U fueled cores are identified by evaluating the sensitivity coefficients of keff, mass balance, and void coefficient. The effect of advanced iron alloy cladding (i.e., FeCrAl) on the performance of Pu conversion in MOX fueled cores is studied instead of using standard stainless-steel cladding. Variations in clad thickness and coolant-to-fuel volume ratio are also exercised. The use of FeCrAl instead of SS as a cladding alloy reduces the required Pu enrichment and improves the Pu conversion rate primarily due to the absence of nickel in the cladding alloy that results in the reduction of the neutron absorption. Also the difference in void coefficients between SS and FeCrAl alloys is nearly 500 pcm over the entire burnup range. The report also shows sensitivity and uncertainty analyses in order to characterize D2O cooled HCPWRs from different aspects. The uncertainties of integral parameters (keff and void coefficient) for selected reactor cores are evaluated at different burnup points in order to find similarities and trends respect to D2O-HCPWR.

Hikaru Hiruta; Gilles Youinou

2013-09-01

400

Perry`s bio-gas experience 1995 ASME/EPRI radwaste workshop  

SciTech Connect

The Perry Power Plant has been in commercial operation for about ten years. Although we didn`t know it at the time, we now believe our bio-gas problem may have started about seven years ago. Barnwell discovered we had a bio-gas problem about a year and a half ago. We found out we had a bio-gas problem a few hours later. The history associated with this process at Perry is outlined, and past as well as present efforts to monitor this process are also discussed.

Schwenk, A.K. [Centerior Energy Corp., North Perry, OH (United States)

1995-09-01

401

The research on new type fast burning systems for biogas engine  

SciTech Connect

In order to meet the demands of energy supply and environmental protection, the large and medium-sized biogas engineering are developed quickly. The biogas engines are also beginning to be developed in China. However, the problems of afterburning and short lifespan of spark ignited biogas engine have not been solved. According to the fast burning theory in gas engines, the authors developed four kinds of new combustion systems which could promote the fast burning of mixture gas and gained good effects. This paper discusses in detail the structural features and experimental results of one combustion system: the Fan shaped combustion chamber.

Xia, L.; Zheng, B.; Chen, Z. [Zhejiang Univ., Hangzhou (China). Dept. of Energy Engineering

1996-12-31

402

Prediction of trace compounds in biogas from anaerobic digestion using the MATLAB Neural Network Toolbox  

Microsoft Academic Search

Abstract The outlook,to apply the highly energetic biogas,from,anaerobic,digestion into fuel cells will result in a significantly higher electrical efficiency and,can contribute,to an increase of renewable,energy,production. The practical bottleneck is the fuel cell poisoning,caused,by several gaseous,trace compounds,like hydrogen,sulfide and,ammonia.,Hence artificial neural networks,were developed,to predict these trace compounds.,The experiments,concluded,that ammonia,in biogas,can indeed,be present up to 93 ppm. Hydrogen,sulfide and ammonia,concentrations,in biogas were

David P. B. T. B. Strik; Alexander M. Domnanovich; Loredana Zani; Rudolf Braun; Peter Holubar

2005-01-01

403

Bioenergy systems report. April 1984: innovations in biogas systems and technology  

SciTech Connect

A comprehensive review of recent innovations in the design and operation of biogas systems is presented. The report contains information on about sixty distinct designs for biogas plants. These include plants designed for use by individual families, larger farm plants, plants used for the digestion of agroindustrial residues, and plants producing or recovering biogas from human wastes and residues. Some have been designed for use in developing countries; others have been used primarily in developed countries but may involve design elements that could be utilized in developing countries.

Mahin, D.B.

1984-04-01

404

Gas-Cooled Fast Breeder Reactor Preliminary Safety Information Document, Amendment 10. GCFR residual heat removal system criteria, design, and performance  

SciTech Connect

This report presents a comprehensive set of safety design bases to support the conceptual design of the gas-cooled fast breeder reactor (GCFR) residual heat removal (RHR) systems. The report is structured to enable the Nuclear Regulatory Commission (NRC) to review and comment in the licensability of these design bases. This report also presents information concerning a specific plant design and its performance as an auxiliary part to assist the NRC in evaluating the safety design bases.

Not Available

1980-09-01

405

Performance of an anaerobic baffled reactor (ABR) as a hydrolysis-acidogenesis unit in treating landfill leachate mixed with municipal sewage  

Microsoft Academic Search

A study on the performance of an Anaerobic Baffled Reactor(ABR) as a hydrolysis-acidogenesis unit in treating the mixed wastewater of landfill leachate and municipal sewage in different volumetric ratios was carried out. The results showed that ABR substantially improved the biological treatability of the mixed wastewater by increasing its BOD5\\/COD ratio to 0.4-0.6 from the initial values of 0.15-0.3. The

B. Wang; Y. Shen

2000-01-01

406

Three-dimensionalization of ultrathin nanosheets in a two-dimensional nano-reactor: macroporous CuO microstructures with enhanced cycling performance.  

PubMed

Three-dimensional (3D) macroporous CuO structures composed of ultrathin nanosheets were successfully synthesized by employing a liquid-liquid interface as a two-dimensional (2D) nano-reactor. The macroporous structure helped CuO to retain the exposed surface during reactions, thus significantly enhancing the long term cycling performance both in photocatalysis and lithium ion batteries. PMID:25406878

Jin, Chuan-Yin; Hu, Ming; Cheng, Xun-Liang; Bu, Fan-Xing; Xu, Li; Zhang, Qing-Hong; Jiang, Ji-Sen

2015-01-01

407

Performance evaluation of a granular activated carbon-sequencing batch biofilm reactor pilot plant system used in treating real wastewater from recycled paper industry  

Microsoft Academic Search

A pilot scale granular activated carbon-sequencing batch biofilm reactor with a capacity of 2.2 m was operated for over three months to evaluate its performance treating real recycled paper industry wastewater under different operational conditions. In this study, dissolved air floatation (DAF) and clarifier effluents were used as influent sources of the pilot plant. During the course of the study, the

Mohd Hafizuddin Muhamad; Siti Rozaimah Sheikh Abdullah; Abu Bakar Mohamad; Rakmi Abdul Rahman; Abdul Amir Hasan Kadhum

2012-01-01

408

Performance and kinetic study of semi-dry thermophilic anaerobic digestion of organic fraction of municipal solid waste.  

PubMed

Anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) is promoted as an energy source and waste disposal. In this study semi dry anaerobic digestion of organic solid wastes was conducted for 45days in a lab-scale batch experiment for total solid concentration of 100g/L for investigating the start-up performances under thermophilic condition (50°C). The performance of the reactor was evaluated by measuring the daily biogas production and calculating the degradation of total solids and the total volatile solids. The biogas yield at the end of the digestion was 52.9L/kg VS (volatile solid) for the total solid (TS) concentration of 100g/L. About 66.7% of the volatile solid degradation was obtained during the digestion. A first order model based on the availability of substrate as the limiting factor was used to perform the kinetic studies of batch anaerobic digestion system. The value of reaction rate constant, k, obtained was 0.0249day(-1). PMID:25449607

Sajeena Beevi, B; Madhu, G; Sahoo, Deepak Kumar

2015-02-01

409

Methanethiol degradation in anaerobic bioreactors at elevated pH (8): reactor performance and microbial community analysis.  

PubMed

The degradation of methanethiol (MT) at 30 degrees C under saline-alkaline (pH 8-10, 0.5M Na(+)) conditions was studied in a lab-scale Upflow Anaerobic Sludge Blanket (UASB) reactor inoculated with estuarine sediment from the Wadden Sea (The Netherlands). At a sodium concentration of 0.5M and a pH between 8 and 9 complete MT degradation to sulfide, methane and carbon dioxide was possible at a maximum loading rate of 22mmolMTL(-1)day(-1) and a hydraulic retention time of 6h. The presence of yeast extract (100mg/L) in the medium was essential for complete MT degradation. 16S rRNA based DGGE and sequence analysis revealed that species related to the genera Methanolobus and Methanosarcina dominated the archaeal community in the reactor sludge. Their relative abundance fluctuated in time, possibly as a result of the changing operational conditions in the reactor. The most dominant MT-degrading archaeon was enriched from the reactor and obtained in pure culture. This strain WR1, which was most closely related to Methanolobus taylorii, degraded MT, dimethyl sulfide (DMS), methanol and trimethylamine. Its optimal growth conditions were 0.2M NaCl, 30 degrees C and pH 8.4. In batch and reactor experiments operated at pH 10, MT was not degraded. PMID:18562196

van Leerdam, Robin C; de Bok, Frank A M; Bonilla-Salinas, Monica; van Doesburg, Wim; Lomans, Bart P; Lens, Piet N L; Stams, Alfons J M; Janssen, Albert J H

2008-12-01

410

Materials performance in CANDU reactors: The first 30 years and the prognosis for life extension and new designs  

NASA Astrophysics Data System (ADS)

A number of CANDU reactors have now been in-service for more than 30 years, and several are planning life extensions. This paper summarizes the major corrosion degradation operating experience of various out-of-core (i.e., excluding fuel channels and fuel) materials in-service in currently operating CANDU reactors. Also discussed are the decisions that need to be made for life extension of replaceable and non-replaceable components such as feeders and steam generators, and materials choices for new designs, such as the advanced CANDU reactor (ACR) and enhanced CANDU-6. The basis for these choices, including a brief summary of the R&D necessary to support such decisions is provided. Finally we briefly discuss the materials and R&D needs beyond the immediate future, including new concepts to improve plant operability and component reliability.

Tapping, R. L.

2008-12-01

411

Diversity and variability of methanogens during the shift from mesophilic to thermohilic conditions while biogas production.  

PubMed

Anaerobic digestion (AD) is the most popular path of organic waste disposal. It is often used in wastewater treatment plants for excessive sludge removal. Methanogenic fermentation had usually been performed under mesophilic conditions, but in the past few years the thermophilic processes have become more popular due to economics and sludge sanitation. Methanogens, the group of microorganisms responsible for methane production, are thought to be sensitive to temperature change and it has already been proven that the communities performing methanogenesis under mesophilic and thermophilic conditions differ. But in most cases the research performed on methanogen diversity and changeability was undertaken in two separate anaerobic chambers for meso- and thermophilic conditions. It is also known that there is a group of microorganisms performing AD which are insensitive to temperature. Also the linkage between digester performance and its microbial content and community changeability is still not fully understood. That is why in this experiment we analyzed the bacterial community performing methanogenesis in a pilot scale anaerobic chamber during the shift from mesophilic to thermophilic conditions to point at the group of temperature tolerant microorganisms and their performance. The research was performed with PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis). It occurred that the community biodiversity decreased together with a temperature increase. The changes were coherent for both the total bacteria community and methanogens. These bacterial shifts were also convergent with biogas production-it decreased in the beginning of the thermophilic phase with the bacterial biodiversity decrease and increased when the community seemed to be restored. DGGE results suggest that among a wide variety of microorganisms involved in AD there is a GC-rich group relatively insensitive towards temperature change, able to adapt quickly to shifts in temperature and perform AD effectively. The studies of this microbial group could be a step forward in developing more efficient anaerobic digestion technology. PMID:25218710

Ziembi?ska-Buczy?ska, A; Banach, A; Bacza, T; Pieczykolan, M

2014-12-01

412

Title: Net Energy Ratio and Greenhouse Gas Analysis of a Biogas Power Plant  

E-print Network

a net efficiency of 1.2% of converting solar energy into electricity and usable, geothermal power plants, bioethanol production facilities, and solar of a Biogas Power Plant Author: W. Bauer Author Affiliation: Department

Bauer, Wolfgang

413

COUPLED ANAEROBIC DIGESTER: WETLAND SYSTEM FOR DAIRY WASTE AND STORMWATER TREATMENT WITH BIOGAS PRODUCTION  

EPA Science Inventory

By coupling wastewater treatment and biogas production, the proposed design will increase sustainability by (i) decreasing pollution of waters, fields, and ecosystems, and (ii) providing a return-on-investment for wastewater and stormwater treatment, (iii) decreasing costs ...

414

Determination of methane emission rates on a biogas plant using data from laser absorption spectrometry.  

PubMed

The aim of the work was to establish a method for emission control of biogas plants especially the observation of fugitive methane emissions. The used method is in a developmental stage but the topic is crucial to environmental and economic issues. A remote sensing measurement method was adopted to determine methane emission rates of a biogas plant in Rhineland-Palatinate, Germany. An inverse dispersion model was used to deduce emission rates. This technique required one concentration measurement with an open path tunable diode laser absorption spectrometer (TDLAS) downwind and upwind the source and basic wind information, like wind speed and direction. Different operating conditions of the biogas plant occurring on the measuring day (December 2013) could be represented roughly in the results. During undisturbed operational modes the methane emission rate averaged 2.8g/s, which corresponds to 4% of the methane gas production rate of the biogas plant. PMID:25446786

Groth, Angela; Maurer, Claudia; Reiser, Martin; Kranert, Martin

2015-02-01

415

Appropriate technology for rural India to produce biogas from vegetative wastes  

SciTech Connect

Most of the huge amount (91%) of energy in rural India is used as domestic fuel. Forest wood constitutes half of this energy, which could be saved by providing an alternative kitchen fuel. Biogas provides the only viable alternative. While the basics of biogas production have been known for several decades, serious research efforts are required to evolve appropriate technology of biogas production for Indian villages. It is easy to design devices which work on the economy of large scale; it is a formidable task to achieve the same at down-to-earth level of economy. Considering the vast majority of small farmers, a cheap, manual, continuous fermentation straw gas plant is likely to offer appropriate technology. Efforts have continued since 1965 to develop such a plant: the latest model is quite competitive in all respects with the KVIC biogas plant, except for its stirring system. Efforts are being made to develop a suitable stirring system.

Goswami, K.P. (College of Agriculture, Gujarat Agricultural Univ., Anand (IN))

1989-01-01

416

Semi-continuous anaerobic co-digestion of dairy manure with three crop residues for biogas production.  

PubMed

The characteristics of anaerobic semi-continuous co-digestion of dairy manure (DM) with three crop straw residues (SRs), rice straw, corn stalks and wheat straw under five mass mixing ratios (SRs/DM) were investigated. During the anaerobic digestion (AD) process, four periods were identified: startup, first stage of stabilization, second stage of stabilization, and suppression. Following the four periods, the biogas production rate varied between 101 and 576mL L(-1)d(-1). A high CH4 content and volatile solid reduction was maintained at the SRs/DM mass mixing ratio 1:9. The highest cumulative biogas production of more than 19L was obtained at ratio 5:5. However, ratio 9:1 performed worst in the whole process. Systematic analysis of the elements revealed nitrogen, phosphorus, and trace elements contents were important for the AD. Overall, the semi-continuous AD is efficient within a wide range of SRs/DM mass mixing ratios. PMID:24525215

Li, Jiang; Wei, Luoyu; Duan, Qiwu; Hu, Guoquan; Zhang, Guozhi

2014-03-01

417

Sensitivity analysis of the waste composition and water content parameters on the biogas production models on solid waste landfills  

NASA Astrophysics Data System (ADS)

Landfills are commonly used as the final deposit of urban solid waste. Despite the waste is previously processed on a treatment plant, the final amount of organic matter which reaches the landfill is large however. The biodegradation of this organic matter forms a mixture of greenhouse gases (essentially Methane and Carbon-Dioxide as well as Ammonia and Hydrogen Sulfide). From the environmental point of view, solid waste landfills are therefore considered to be one of the main greenhouse gas sources. Different mathematical models are usually applied to predict the amount of biogas produced on real landfills. The waste chemical composition and the availability of water in the solid waste appear to be the main parameters of these models. Results obtained when performing a sensitivity analysis over the biogas production model parameters under real conditions are shown. The importance of a proper characterizacion of the waste as well as the necessity of improving the understanding of the behaviour and development of the water on the unsaturated mass of waste are emphasized.

Rodrigo-Ilarri, Javier; Segura-Sobrino, Francisco; Rodrigo-Clavero, Maria-Elena

2014-05-01

418

Pretreatment of microalgae to improve biogas production: a review.  

PubMed

Microalgae have been intensively studied as a source of biomass for replacing conventional fossil fuels in the last decade. The optimization of biomass production, harvesting and downstream processing is necessary for enabling its full-scale application. Regarding biofuels, biogas production is limited by the characteristics of microalgae, in particular the complex cell wall structure of most algae species. Therefore, pretreatment methods have been investigated for microalgae cell wall disruption and biomass solubilization before undergoing anaerobic digestion. This paper summarises the state of the art of different pretreatment techniques used for improving microalgae anaerobic biodegradability. Pretreatments were divided into 4 categories: (i) thermal; (ii) mechanical; (iii) chemical and (iv) biological methods. According to experimental results, all of them are effective at increasing biomass solubilization and methane yield, pretreatment effect being species dependent. Pilot-scale research is still missing and would help evaluating the feasibility of full-scale implementation. PMID:25257071

Passos, Fabiana; Uggetti, Enrica; Carrère, Hélène; Ferrer, Ivet

2014-11-01

419

Effects of increasing organic loading rate on performance and microbial community shift of an up-flow anaerobic sludge blanket reactor treating diluted pharmaceutical wastewater.  

PubMed

The performance of an up-flow anaerobic sludge blanket (UASB) reactor was investigated in the treatment of diluted pharmaceutical fermentation wastewater for a continuous operation of 140 days. The dynamics and compositions of the microbial community were monitored using polymerase chain reaction (PCR)-restriction fragment length polymorphism (PCR-RFLP) analysis. Increase of the organic loading rate (OLR) from 2.7 kg COD/m(3) d to 7.2 COD/m(3) d led to an increase in the COD removal efficiency from 83% to 91%. The dominant bacteria shifted from Proteobacteria (23.8%), Chloroflexi (14.5%) and Firmicutes (4.0%) to Firmicutes (48.4%), Bacteroidetes (9.5%) and Proteobacteria (5.4%). For archeaon, the dominant groups changed from Thermoplasmata (24.4%), Thermoprotei (18.0%) and Methanobacteria (30.8%) to Thermoplasmata (70.4%) and Methanomicrobia (16.8%). Firmicutes, Bacteroidetes, Thermoplasmata and Methanobacteria could outcompete other species and dominated in the reactor under higher OLR. The results indicated that, to some extent, microbial community shift could reflect the performance of the reactor and a significant community shift corresponded to a considerable process event. PMID:24725962

Chen, Zhu; Wang, Yuguang; Li, Kai; Zhou, Hongbo

2014-09-01

420

Biogas production from co-digestion of dairy manure and food waste  

Microsoft Academic Search

The effect of manure-screening on the biogas yield of dairy manure was evaluated in batch digesters under mesophilic conditions (35°C). Moreover, the study determined the biogas production potential of different mixtures of unscreened dairy manure and food waste and compared them with the yield from manure or food waste alone. A first-order kinetics model was developed to calculate the methane

Hamed M. El-Mashad; Ruihong Zhang

2010-01-01

421

Environmental systems analysis of biogas systems—Part I: Fuel-cycle emissions  

Microsoft Academic Search

Fuel-cycle emissions of carbon dioxide (CO2), carbon oxide (CO), nitrogen oxides (NOx), sulphur dioxide (SO2), hydrocarbons (HC), methane (CH4), and particles are analysed from a life-cycle perspective for different biogas systems based on six different raw materials. The gas is produced in large- or farm-scale biogas plants, and is used in boilers for heat production, in turbines for co-generation of

Pål Börjesson; Maria Berglund

2006-01-01

422

Effects of Levels of Automation for Advanced Small Modular Reactors: Impacts on Performance, Workload, and Situation Awareness  

SciTech Connect

The Human-Automation Collaboration (HAC) research effort is a part of the Department of Energy (DOE) sponsored Advanced Small Modular Reactor (AdvSMR) program conducted at Idaho National Laboratory (INL). The DOE AdvSMR program focuses on plant design and management, reduction of capital costs as well as plant operations and maintenance costs (O&M), and factory production costs benefits.

Johanna Oxstrand; Katya Le Blanc

2014-07-01

423

Performance of on-site pilot static granular bed reactor (SGBR) for treating dairy processing wastewater and chemical oxygen demand balance modeling under different operational conditions.  

PubMed

The performance and operational stability of a pilot-scale static granular bed reactor (SGBR) for the treatment of dairy processing wastewater were investigated under a wide range of organic and hydraulic loading rates and temperature conditions. The SGBR achieved average chemical oxygen demand (COD), biological oxygen demand (BOD), and total suspended solids (TSS)-removal efficiencies higher than 90 % even at high loading rates up to 7.3 kg COD/m(3)/day, with an hydraulic retention time (HRT) of 9 h, and at low temperatures of 11 °C. The average methane yield of 0.26 L CH4/g CODremoved was possibly affected by a high fraction of particulate COD and operation at low temperatures. The COD mass balance indicated that soluble COD was responsible for most of the methane production. The reactor showed the capacity of the methanogens to maintain their activity and withstand organic and hydraulic shock loads. PMID:25164570

Oh, Jin Hwan; Park, Jaeyoung; Ellis, Timothy G

2015-02-01

424

Enhancement of biogas production from swine manure by a lignocellulolytic microbial consortium.  

PubMed

Anaerobic digestion of lignocellulosic wastes is limited by inefficient hydrolysis of recalcitrant substrates, leading to low biogas yield. In this study, the potential of a lignocellulolytic microbial consortium (LMC) for enhancing biogas production from fibre-rich swine manure (SM) was assessed. Biochemical methane potential assay showed that inoculation of structurally stable LMC to anaerobic digestion led to increase biogas production under mesophilic and thermophilic conditions. The greatest enhancement was observed at 37°C with a LMC/SM ratio of 1.5:1 mg VSS/g VS leading to biogas and methane yields of 355 and 180 ml/g VS(added) respectively, equivalent to 40% and 55% increases compared with the control. The LMC was shown to increase the efficiency of total solid, chemical oxygen demand removal and degradation of cellulose and hemicelluloses (1.87 and 1.65-fold, respectively). The LMC-supplemented process was stable over a 90 d biogas production period. This work demonstrates the potential of LMC for enhancing biogas from lignocellulosic wastes. PMID:23896438

Tuesorn, Suchada; Wongwilaiwalin, Sarunyou; Champreda, Verawat; Leethochawalit, Malinee; Nopharatana, Annop; Techkarnjanaruk, Somkiet; Chaiprasert, Pawinee

2013-09-01

425

Economic evaluation of biogas as energy and fertilizer in rural northeast Thailand  

SciTech Connect

In the aftermath of the 1974 oil crisis, Thailand faces a complex problem: agriculture is characterized by low productivity, and an increasing burden is now being placed on national forest reserves as the primary source of fuel. The nation is forced to choose: land for forests and fuel, or land for agriculture and food. In either case, current levels of land use are having serious environmental consequences. Biogas has been proposed as a possible remedy to alleviate these problems. In this study, three sizes of biogas plants are studied to facilitate cost estimates, and two Thai villages provide case studies of actual applications. Then a stratified random sample of 60 households is selected from the two villages, based on economic class groupings. The central question is to inquire whether biogas is feasible and profitable for villages with differing characteristics, for different income groups within those villages, and whether technological viability is affected by plant size. The results show that there are increasing returns to scale for larger biogas plants; that the poorer village obtains more benefits per unit of output than the more modernized village; that the poorest households within each village have the highest potential gains from biogas. It is recommended that Thailand implement biogas technology in those regions and for those villages where benefit-cost analysis demonstrates its economic feasibility.

Sombuntham, S.

1982-01-01

426