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1.
Integrated biogas upgrading and hydrogen utilization in an anaerobic reactor containing enriched hydrogenotrophic methanogenic culture 总被引:1,自引:0,他引:1
Biogas produced by anaerobic digestion, is mainly used in a gas motor for heat and electricity production. However, after removal of CO2, biogas can be upgraded to natural gas quality, giving more utilization possibilities, such as utilization as autogas, or distant utilization by using the existing natural gas grid. The current study presents a new biological method for biogas upgrading in a separate biogas reactor, containing enriched hydrogenotrophic methanogens and fed with biogas and hydrogen. Both mesophilic‐ and thermophilic anaerobic cultures were enriched to convert CO2 to CH4 by addition of H2. Enrichment at thermophilic temperature (55°C) resulted in CO2 and H2 bioconversion rate of 320 mL CH4/(gVSS h), which was more than 60% higher than that under mesophilic temperature (37°C). Different dominant species were found at mesophilic‐ and thermophilic‐enriched cultures, as revealed by PCR–DGGE. Nonetheless, they all belonged to the order Methanobacteriales, which can mediate hydrogenotrophic methanogenesis. Biogas upgrading was then tested in a thermophilic anaerobic reactor under various operation conditions. By continuous addition of hydrogen in the biogas reactor, high degree of biogas upgrading was achieved. The produced biogas had a CH4 content, around 95% at steady‐state, at gas (mixture of biogas and hydrogen) injection rate of 6 L/(L day). The increase of gas injection rate to 12 L/(L day) resulted in the decrease of CH4 content to around 90%. Further study showed that by decreasing the gas–liquid mass transfer by increasing the stirring speed of the mixture the CH4 content was increased to around 95%. Finally, the CH4 content around 90% was achieved in this study with the gas injection rate as high as 24 L/(L day). Biotechnol. Bioeng. 2012; 109: 2729–2736. © 2012 Wiley Periodicals, Inc. 相似文献
2.
In situ biogas upgrading was conducted by introducing H2 directly to the anaerobic reactor. As H2 addition is associated with consumption of the CO2 in the biogas reactor, pH increased to higher than 8.0 when manure alone was used as substrate. By co-digestion of manure with acidic whey, the pH in the anaerobic reactor with the addition of hydrogen could be maintained below 8.0, which did not have inhibition to the anaerobic process. The H2 distribution systems (diffusers with different pore sizes) and liquid mixing intensities were demonstrated to affect the gas-liquid mass transfer of H2 and the biogas composition. The best biogas composition (75:6.6:18.4) was obtained at stirring speed 150 rpm and using ceramic diffuser, while the biogas in the control reactor consisted of CH4 and CO2 at a ratio of 55:45. The consumed hydrogen was almost completely converted to CH4, and there was no significant accumulation of VFA in the effluent. The study showed that addition of hydrogen had positive effect on the methanogenesis, but had no obvious effect on the acetogenesis. Both hydrogenotrophic methanogenic activity and the concentration of coenzyme F420 involved in methanogenesis were increased. The archaeal community was also altered with the addition of hydrogen, and a Methanothermobacter thermautotrophicus related band appeared in a denaturing gradient gel electrophoresis gel from the sample of the reactor with hydrogen addition. Though the addition of hydrogen increased the dissolved hydrogen concentration, the degradation of propionate was still thermodynamically feasible at the reactor conditions. 相似文献
3.
Simultaneous hydrogen utilization and in situ biogas upgrading in an anaerobic reactor 总被引:2,自引:0,他引:2
Luo G Johansson S Boe K Xie L Zhou Q Angelidaki I 《Biotechnology and bioengineering》2012,109(4):1088-1094
The possibility of converting hydrogen to methane and simultaneous upgrading of biogas was investigated in both batch tests and fully mixed biogas reactor, simultaneously fed with manure and hydrogen. Batch experiments showed that hydrogen could be converted to methane by hydrogenotrophic methanogenesis with conversion of more than 90% of the consumed hydrogen to methane. The hydrogen consumption rates were affected by both (hydrogen partial pressure) and mixing intensity. Inhibition of propionate and butyrate degradation by hydrogen (1 atm) was only observed under high mixing intensity (shaking speed 300 rpm). Continuous addition of hydrogen (flow rate of 28.6 mL/(L/h)) to an anaerobic reactor fed with manure, showed that more than 80% of the hydrogen was utilized. The propionate and butyrate level in the reactor was not significantly affected by the hydrogen addition. The methane production rate of the reactor with H2 addition was 22% higher, compared to the control reactor only fed with manure. The CO2 content in the produced biogas was only 15%, while it was 38% in the control reactor. However, the addition of hydrogen resulted in increase of pH (from 8.0 to 8.3) due to the consumption of bicarbonate, which subsequently caused slight inhibition of methanogenesis. Biotechnol. Bioeng. 2012; 109:1088–1094. © 2011 Wiley Periodicals, Inc. 相似文献
4.
The effect of copper (added as CuCl2) on the anaerobic co-digestion of Phragmites straw and cow dung was studied in pilot experiments by investigating the biogas properties, process stability, substrate degradation and enzyme activities at different stages of mesophilic fermentation. The results showed that 30 and 100 mg/L Cu2+ addition increased the cumulative biogas yields by up to 43.62 and 20.77% respectively, and brought forward the daily biogas yield peak, while 500 mg/L Cu2+ addition inhibited biogas production. Meanwhile, the CH4 content in the 30 and 100 mg/L Cu2+-added groups was higher than that in the control group. Higher pH values (close to pH 7) and lower oxidation–reduction potential (ORP) values in the Cu2+-added groups after the 8th day indicated better process stability compared to the control group. In the presence of Cu2+, the degradation of volatile fatty acids (VFAs) and other organic molecules (represented by chemical oxygen demand, COD) generated from hydrolysis was enhanced, and the ammonia nitrogen (NH4 +-N) concentrations were more stable than in the control group. The contents of lignin and hemicellulose in the substrate declined in the Cu2+-added groups while the cellulose contents did not. Neither the cellulase nor the coenzyme F420 activities could determine the biogas producing efficiency. Taking the whole fermentation process into account, the promoting effect of Cu2+ addition on biogas yields was mainly attributable to better process stability, the enhanced degradation of lignin and hemicellulose, the transformation of intermediates into VFA, and the generation of CH4 from VFA. 相似文献
5.
Treatment of food processing wastewater in a full-scale jet biogas internal loop anaerobic fluidized bed reactor 总被引:1,自引:0,他引:1
Chaohai Wei Tao Zhang Chunhua Feng Haizhen Wu Zhiyi Deng Chaofei Wu Bin Lu 《Biodegradation》2011,22(2):347-357
A full-scale jet biogas internal loop anaerobic fluidized bed (JBILAFB) reactor, which requires low energy input and allows
enhanced mass transfer, was constructed for the treatment of food processing wastewater. This reactor has an active volume
of 798 m3 and can treat 33.3 m3 wastewater per hour. After pre-treating the raw wastewater by settling, oil separating and coagulation-air floating processes,
the reactor was operated with a relatively shorter start-up time (55 days). Samples for the influent and effluent of the JBILAFB
reactor were taken and analyzed daily for the whole process including both the start-up and stable running periods. When the
volumetric COD loading fluctuated in the range of 1.6–5.6 kg COD m−3 day−1, the COD removal efficiency, the volatile fatty acid(VFA)/alkalinity ratio, the maximum biogas production and the content
of CH4 in total biogas of the reactor were found to be 80.1 ± 5%, 0.2–0.5, 348.5 m3 day−1 and 94.5 ± 2.5%, respectively. Furthermore, the scanning electron microscope (SEM) results showed that anaerobic granular
sludge and microorganism particles with biofilm coexisted in the reactor, and that the bacteria mainly in bacilli and cocci
were observed as predominant species. All the data demonstrated that the enhanced mass transfer for gas, liquid and solid
phases was achieved, and that the formation of microorganism granules and the removal of inhibitors increased the stability
of the system. 相似文献
6.
Sarah Refai Kati Wassmann Uwe Deppenmeier 《Applied microbiology and biotechnology》2014,98(16):7271-7280
Biochemical processes in biogas plants are still not fully understood. Especially, the identification of possible bottlenecks in the complex fermentation processes during biogas production might provide potential to increase the performance of biogas plants. To shed light on the question which group of organism constitutes the limiting factor in the anaerobic breakdown of organic material, biogas sludge from different mesophilic biogas plants was examined under various conditions. Therefore, biogas sludge was incubated and analyzed in anaerobic serum flasks under an atmosphere of N2/CO2. The batch reactors mirrored the conditions and the performance of the full-scale biogas plants and were suitable test systems for a period of 24 h. Methane production rates were compared after supplementation with substrates for syntrophic bacteria, such as butyrate, propionate, or ethanol, as well as with acetate and H2+CO2 as substrates for methanogenic archaea. Methane formation rates increased significantly by 35 to 126 % when sludge from different biogas plants was supplemented with acetate or ethanol. The stability of important process parameters such as concentration of volatile fatty acids and pH indicate that ethanol and acetate increase biogas formation without affecting normally occurring fermentation processes. In contrast to ethanol or acetate, other fermentation products such as propionate, butyrate, or H2 did not result in increased methane formation rates. These results provide evidence that aceticlastic methanogenesis and ethanol-oxidizing syntrophic bacteria are not the limiting factor during biogas formation, respectively, and that biogas plant optimization is possible with special focus on methanogenesis from acetate. 相似文献
7.
Hydrogen and methane production from desugared molasses by a two‐stage thermophilic anaerobic process was investigated in a series of two up‐flow anaerobic sludge blanket (UASB) reactors. The first reactor that was dominated with hydrogen‐producing bacteria of Thermoanaerobacterium thermosaccharolyticum and Thermoanaerobacterium aciditolerans could generate a high hydrogen production rate of 5600 mL H2/day/L, corresponding to a yield of 132 mL H2/g volatile solid (VS). The effluent from the hydrogen reactor was further converted to methane in the second reactor with the optimal production rate of 3380 mL CH4/day/L, corresponding to a yield of 239 mL CH4/g VS. Aceticlastic Methanosarcina mazei was the dominant methanogen in the methanogenesis stage. This work demonstrates that biohydrogen production can be very efficiently coupled with a subsequent step of methane production using desugared molasses. Furthermore, the mixed gas with a volumetric content of 16.5% H2, 38.7% CO2, and 44.8% CH4, containing approximately 15% energy by hydrogen is viable to be bio‐hythane. 相似文献
8.
The optimization of a two-phase thermophilic anaerobic process treating biowaste for hydrogen and methane production was carried out at pilot scale using two stirred reactors (CSTRs) and without any physical/chemical pre-treatment of inoculum. During the experiment the hydrogen production at low hydraulic retention time (3d) was tested, both with and without reject water recirculation and at two organic loading rate (16 and 21 kgTVS/m3d). The better yields were obtained with recirculation where the pH reached an optimal value (5.5) thanks to the buffering capacity of the recycle stream. The specific gas production of the first reactor was 51 l/kgVSfed and H2 content in biogas 37%. The mixture of gas obtained from the two reactors met the standards for the biohythane mix only when lower loading rate were applied to the first reactor, with a composition of 6.7% H2, 40.1% CO2 and 52.3% CH4 the overall SGP being 0.78 m3/kgVSfed. 相似文献
9.
Background
Food waste is a large bio-resource that may be converted to biogas that can be used for heat and power production, or as transport fuel. We studied the anaerobic digestion of food waste in a staged digestion system consisting of separate acidogenic and methanogenic reactor vessels. Two anaerobic digestion parameters were investigated. First, we tested the effect of 55 vs. 65 °C acidogenic reactor temperature, and second, we examined the effect of reducing the hydraulic retention time (HRT) from 17 to 10 days in the methanogenic reactor. Process parameters including biogas production were monitored, and the microbial community composition was characterized by 16S amplicon sequencing.Results
Neither organic matter removal nor methane production were significantly different for the 55 and 65 °C systems, despite the higher acetate and butyrate concentrations observed in the 65 °C acidogenic reactor. Ammonium levels in the methanogenic reactors were about 950 mg/L NH4 + when HRT was 17 days but were reduced to 550 mg/L NH4 + at 10 days HRT. Methane production increased from ~ 3600 mL/day to ~ 7800 when the HRT was decreased. Each reactor had unique environmental parameters and a correspondingly unique microbial community. In fact, the distinct values in each reactor for just two parameters, pH and ammonium concentration, recapitulate the separation seen in microbial community composition. The thermophilic and mesophilic digesters were particularly distinct from one another. The 55 °C acidogenic reactor was mainly dominated by Thermoanaerobacterium and Ruminococcus, whereas the 65 °C acidogenic reactor was initially dominated by Thermoanaerobacterium but later was overtaken by Coprothermobacter. The acidogenic reactors were lower in diversity (34–101 observed OTU0.97, 1.3–2.5 Shannon) compared to the methanogenic reactors (472–513 observed OTU0.97, 5.1–5.6 Shannon). The microbial communities in the acidogenic reactors were > 90% Firmicutes, and the Euryarchaeota were higher in relative abundance in the methanogenic reactors.Conclusions
The digestion systems had similar biogas production and COD removal rates, and hence differences in temperature, NH4 + concentration, and pH in the reactors resulted in distinct but similarly functioning microbial communities over this range of operating parameters. Consequently, one could reduce operational costs by lowering both the hydrolysis temperature from 65 to 55 °C and the HRT from 17 to 10 days.10.
In this study, the utilization of potato-juice, the organic by-product from potato-starch processing, for biogas production was investigated in batch assay and in high rate anaerobic reactors. The maximum methane potential of the potato-juice determined by batch assay was 470 mL-CH4/gVS-added. Anaerobic digestion of potato-juice in an EGSB reactor could obtain a methane yield of 380 mL-CH4/gVS-added at the organic loading rate of 3.2 gCOD/(L-reactor.d). In a UASB reactor, higher organic loading rate of 5.1 gCOD/(L-reactor.d) could be tolerated, however, it resulted in a lower methane yield of 240 mL-CH4/gVS-added. The treatment of reactor effluent was also investigated. By acidification with sulfuric acid to pH lower than 5, almost 100% of the ammonia content in the effluent could be retained during the successive up-concentration process step. The reactor effluent could be up-concentrated by evaporation to minimize its volume, and later be utilized as fertilizer. 相似文献
11.
Anammox start-up in sequencing batch biofilm reactors using different inoculating sludge 总被引:1,自引:0,他引:1
In this study, anammox bacteria were rapidly enriched in sequencing batch biofilm reactors (SBBRs) with different inoculations. The activated sludge taken from a sequencing batch reactor was used and inoculated to SBBR1, while SBBR2 was seeded with stored anaerobic sludge from an upflow anaerobic fixed bed (2-year stored at 5–15 °C). Nitrogen removal performance, anammox activity, biofilm characteristics and variation of the microbial community were evaluated. The maximum total nitrogen loading rate (NLR) of SBBR1 gradually reached to 1.62 kg?N/(m3/day) with a removal efficiency higher than 88 % and the NLR of SBBR2 reached to 1.43 kg?N/(m3/day) with a removal efficiency of 86 %. SBBR2 was more stable compared to SBBR1. These results, combined with molecular techniques such as scanning electron microscope, fluorescence in situ hybridization, and terminal restriction fragment length polymorphism, indicated that different genera of anammox bacteria became dominant. This research also demonstrates that SBBR is a promising bioreactor for starting up and enriching anammox bacteria. 相似文献
12.
Nikolaos Venetsaneas Georgia AntonopoulouKaterina Stamatelatou Michael KornarosGerasimos Lyberatos 《Bioresource technology》2009,100(15):3713-3717
This study focuses on the exploitation of cheese whey as a source for hydrogen and methane, in a two-stage continuous process. Mesophilic fermentative hydrogen production from undiluted cheese whey was investigated at a hydraulic retention time (HRT) of 24 h. Alkalinity addition (NaHCO3) or an automatic pH controller were used, to maintain the pH culture at a constant value of 5.2. The hydrogen production rate was 2.9 ± 0.2 L/Lreactor/d, while the yield of hydrogen produced was approximately 0.78 ± 0.05 mol H2/mol glucose consumed, with alkalinity addition, while the respective values when using pH control were 1.9 ± 0.1 L/Lreactor/d and 0.61 ± 0.04 mol H2/mol glucose consumed. The corresponding yields of hydrogen produced were 2.9 L of H2/L cheese whey and 1.9 L of H2/L cheese whey, respectively. The effluent from the hydrogenogenic reactor was further digested to biogas in a continuous mesophilic anaerobic bioreactor. The anaerobic digester was operated at an HRT of 20d and produced approximately 1 L CH4/d, corresponding to a yield of 6.7 L CH4/L of influent. The chemical oxygen demand (COD) elimination reached 95.3% demonstrating that cheese whey could be efficiently used for hydrogen and methane production, in a two-stage process. 相似文献
13.
Feeding approaches for biogas production from animal wastes and industrial effluents 总被引:1,自引:0,他引:1
A.P. Francese G. Aboagye-Mathiesen T. Olesen P.R. Córdoba F. Siñeriz 《World journal of microbiology & biotechnology》2000,16(2):147-150
Different feeding approaches were applied to a 5 l anaerobic digester in order to improve the biogas production. During operation, the reactor was fed with a mixture (9.7% w/v total solids (TS) and 7.6% w/v volatile solids (VS) in average) of pig manure with fish oil waste and waste from bentonite of edible oil filtration process, at different intervals of 24, 12 and 4 h at 15 days of hydraulic retention time. Production and quality of the biogas were practically constant at 183.7 ml (average) of biogas per gram of volatile solids available in the reactor per day, and the best biogas composition was 73.6% v/v CH4 and 26.4% v/v CO2. 相似文献
14.
《Systematic and applied microbiology》2020,43(1):126024
Conventional anaerobic digesters intended for the production of biogas usually operate in complete darkness. Therefore, little is known about the effect of light on their microbial communities. In the present work, 16S rRNA gene amplicon Nanopore sequencing and shotgun metagenomic sequencing were used to study the taxonomic and functional structure of the microbial community forming a biofilm on the inner wall of a laboratory-scale transparent anaerobic biodigester illuminated with natural sunlight. The biofilm was composed of microorganisms involved in the four metabolic processes needed for biogas production, and it was surprisingly rich in Rhodopseudomonas faecalis, a versatile bacterium able to carry out photoautotrophic metabolism when grown under anaerobic conditions. The results suggested that this bacterium, which is able to fix carbon dioxide, could be considered for use in transparent biogas fermenters in order to contribute to the production of optimized biogas with a higher CH4:CO2 ratio than the biogas produced in regular, opaque digesters. To the best of our knowledge, this is the first study characterising the phototrophic biofilm associated with illuminated bioreactors. 相似文献
15.
Hyun Chul Shin Dong-Hun Ju Byoung Seung Jeon Okkyoung Choi Hyun Wook Kim Youngsoon Um Dong-Hoon Lee Byoung-In Sang 《PloS one》2015,10(12)
Hydrogenotrophic methanogens can use gaseous substrates, such as H2 and CO2, in CH4 production. H2 gas is used to reduce CO2. We have successfully operated a hollow-fiber membrane biofilm reactor (Hf-MBfR) for stable and continuous CH4 production from CO2 and H2. CO2 and H2 were diffused into the culture medium through the membrane without bubble formation in the Hf-MBfR, which was operated at pH 4.5–5.5 over 70 days. Focusing on the presence of hydrogenotrophic methanogens, we analyzed the structure of the microbial community in the reactor. Denaturing gradient gel electrophoresis (DGGE) was conducted with bacterial and archaeal 16S rDNA primers. Real-time qPCR was used to track changes in the community composition of methanogens over the course of operation. Finally, the microbial community and its diversity at the time of maximum CH4 production were analyzed by pyrosequencing methods. Genus Methanobacterium, related to hydrogenotrophic methanogens, dominated the microbial community, but acetate consumption by bacteria, such as unclassified Clostridium sp., restricted the development of acetoclastic methanogens in the acidic CH4 production process. The results show that acidic operation of a CH4 production reactor without any pH adjustment inhibited acetogenic growth and enriched the hydrogenotrophic methanogens, decreasing the growth of acetoclastic methanogens. 相似文献
16.
Kyohei Baito Satomi Imai Makoto Matsushita Miku Otani Yu Sato Hiroyuki Kimura 《Microbial biotechnology》2015,8(5):837-845
In a deep aquifer associated with an accretionary prism, significant methane (CH4) is produced by a subterranean microbial community. Here, we developed bioreactors for producing CH4 and hydrogen (H2) using anaerobic groundwater collected from the deep aquifer. To generate CH4, the anaerobic groundwater amended with organic substrates was incubated in the bioreactor. At first, H2 was detected and accumulated in the gas phase of the bioreactor. After the H2 decreased, rapid CH4 production was observed. Phylogenetic analysis targeting 16S rRNA genes revealed that the H2-producing fermentative bacterium and hydrogenotrophic methanogen were predominant in the reactor. The results suggested that syntrophic biodegradation of organic substrates by the H2-producing fermentative bacterium and the hydrogenotrophic methanogen contributed to the CH4 production. For H2 production, the anaerobic groundwater, amended with organic substrates and an inhibitor of methanogens (2-bromoethanesulfonate), was incubated in a bioreactor. After incubation for 24 h, H2 was detected from the gas phase of the bioreactor and accumulated. Bacterial 16S rRNA gene analysis suggested the dominance of the H2-producing fermentative bacterium in the reactor. Our study demonstrated a simple and rapid CH4 and H2 production utilizing anaerobic groundwater containing an active subterranean microbial community. 相似文献
17.
AbstractBiogas from anaerobic digestion of biological wastes is a renewable energy resource that mainly contains CH4, CO2, trace amounts of H2S and a fraction of H2O vapour. In order to transfer biogas into biomethane to meet the standards for use as vehicle fuel or for injection in the natural gas grid, removing H2S from biogas in advance is necessary. In addition, biogas is usually saturated with water vapour. It is significant to study the effect of the presence of H2O on the biogas separation performance. Adsorption of H2S/CO2/CH4 and H2O/CO2/CH4 ternary mixtures using single-walled carbon nanotubes (SWCNT) were investigated via the Grand Canonical Monte Carlo (GCMC) method. We studied the effects of carbon nanotube diameter, –COOH modification, temperature and pressure on H2S adsorption. The results indicate that the presence of hydrophilic –COOH groups does affect the separation of H2S/CO2/CH4 mixtures. Temperature swing adsorption is more suitable than pressure swing adsorption for the separation of H2S/CO2/CH4 mixtures. The effect of water vapour on the separation of CO2/CH4 was also investigated. The result shows that the presence of H2O has little effect on the selectivity of CO2/CH4 in pristine CNT, but the selectivity of CO2/CH4 with the presence of H2O is markedly enhanced after modification in –COOH modified SWCNT with specific modification degree. It is expected that this work could provide some useful information for biogas upgrading. 相似文献
18.
L. C. W. MacLean T. J. Pray T. C. Onstott E. L. Brodie T. C. Hazen G. Southam 《Geomicrobiology journal》2013,30(6):491-504
A biofilm sample was collected from an anaerobic water and gas-flowing borehole, 1.474 km below land surface in the Evander Au mine, Republic of South Africa. The biofilm was 27 wt% ZnS, which was ~ 2 × 107times more concentrated than the dissolved Zn measured in the borehole water. X-Ray diffraction indicated that the Zn was present in the form of fine grained, 4.7 ± 0.9 nm particles with smaller amounts of pyrite (FeS 2 ). Scanning electron microscopy, coupled with energy-dispersive X-ray spectroscopy confirmed the identity of these minerals in the biofilm. Using transmission electron microscopy, the fine-grained ZnS minerals were found to coat the 1 μ m-diameter rod-shaped bacteria that made up the primary substructure of the biofilm. The FeS 2 was present as framboids (spherical aggregates of 0.5–1 μ m FeS 2 crystals) up to 10 μ m in diameter and as large, 2–3 μ m euhedral crystals that were not nucleated on the bacterial surfaces, but were found within the biofilm. Analyses of 16S rDNA utilizing clone libraries and a phylochip indicates that the ZnS rich biofilm is dominated by methanogens with a significant sulfate-reducing bacterial population and minor sulfide and CH 4 -oxidizing chemolithotrophs. This biofilm community is sustained by sulfate, bicarbonate and H 2 -bearing paleometeoric water. 相似文献
19.
Yonglan Tian Huayong Zhang Yang Chai Lijun Wang Xueyue Mi Luyi Zhang Maxwell Adam Ware 《Biodegradation》2017,28(1):15-25
The importance of nickel (added as NiCl2) on mesophilic anaerobic fermentation of Phragmites australis straw and cow dung was demonstrated by investigating the biogas properties, pH values, organic matter degradation [chemical oxygen demand (COD)] and enzyme activities (cellulase, protease and dehydrogenase) during the fermentation process. The results showed that Ni2+ addition increased the cumulative biogas yields by >18 % by improving the efficiency of first peak stage and bringing forward the second peak stage. The pH values were not significantly influenced by Ni2+ addition (p > 0.05). Biogas yields were associated with variations in COD concentrations rather than momentary concentrations. At the start-up stage of fermentation (4th day), the biogas yields increased gradually together with the increase of dehydrogenase activities at elevated Ni2+ concentrations when cellulase and protease activities were similar in all test groups. It is suggested that Ni2+ addition was mainly dependent on the methanogenic stage. After the start-up stage, the impact of Ni2+ addition on biogas production was mainly dependent on its effect on cellulase activities, rather than protease or dehydrogenase activities. 相似文献
20.
《Journal of Fermentation and Bioengineering》1991,71(3):203-205
For microbial production of CH4 from H2 and CO2, a hollow fiber reactor had been developed to increase an interfacial area between liquid and gas phases. The CH4 production with the hollow fiber reactor was analyzed by applying a plug flow reaction model of a tubular reactor. It was possible to apply the model to the reaction of CH4 production. The relationships between influent gas velocity, length of reactor and reaction yield were simulated by the reaction model. The plug flow reaction model was useful to design a hollow fiber bioreactor for the biomethanation of H2 and CO2. 相似文献