The effect of substrate concentration ranging from 0 to 300 g/L on fermentative hydrogen production by mixed cultures was investigated in batch tests using glucose as substrate. The experimental results showed that, a...The effect of substrate concentration ranging from 0 to 300 g/L on fermentative hydrogen production by mixed cultures was investigated in batch tests using glucose as substrate. The experimental results showed that, at 35 and initial pH 7.0, during the fermentative hydrogen production, the hydrogen °C production potential and hydrogen production rate increased with increasing substrate concentration from 0 to 25 g/L. The maximal hydrogen production potential of 426.8 mL and maximal hydrogen production rate of 15.1 mL/h were obtained at the substrate concentration of 25 g/L. The maximal hydrogen yield and the maximal substrate degradation efficiency were respectively 384.3 mL/g glucose and 97.6%, at the substrate concentration of 2 g/L. The modified Logistic model could be used to describe the progress of cumulative hydrogen production in this study successfully. The Han-Levenspiel model could be used to describe the effect of substrate concentration on fermentative hydrogen production rate.展开更多
While reliance on renewable energy resources has become a reality, there is still a need to deploy greener and more sustainable methods in order to achieve sustainable development goals. Indeed, green hydrogen is curr...While reliance on renewable energy resources has become a reality, there is still a need to deploy greener and more sustainable methods in order to achieve sustainable development goals. Indeed, green hydrogen is currently believed to be a reliable solution for global warming and the pollution challenges arising from fossil fuels, making it the resilient fuel of the future. However, the sustainability of green hydrogen technologies is yet to be achieved. In this context, generation of green hydrogen with the aid of deep eutectic solvents(DESs) as green mixtures has been demonstrated as a promising research area. This systematic review article covers green hydrogen generation through water splitting and biomass fermentation when DESs are utilized within the generation process. It also discusses the incorporation of DESs in fuel cell technologies. DESs can play a variety of roles such as solvent, electrolyte, or precursor;colloidal suspension and reaction medium;galvanic replacement, shape-controlling, decoration, or extractive agent;finally oxidant. These roles are relevant to several methods of green hydrogen generation, including electrocatalysis, photocatalysis, and fermentation. As such, it is of utmost importance to screen potential DES formulations and determine how they can function in and contribute throughout the green hydrogen mobility stages. The realization of super green hydrogen generation stands out as a pivotal milestone in our journey towards achieving a more sustainable form of development;DESs have great potential in making this milestone achievable. Overall, incorporating DESs in hydrogen generation constitutes a promising research area and offers potential scalability for green hydrogen production, storage,transport, and utilization.展开更多
Five individual pretreatment methods, including three widely-used protocols （heat, acid and base） and two novel attempts （ultrasonic and ultraviolet）, were conducted in batch tests to compare their effects on mixe...Five individual pretreatment methods, including three widely-used protocols （heat, acid and base） and two novel attempts （ultrasonic and ultraviolet）, were conducted in batch tests to compare their effects on mixed microflora to enhance hydrogen （H2） production from corn stover hydrolysate. Experimental results indicated that heat and base pretreatments significantly increased H2 yield with the values of 5.03 and 4.45 mmol H2/g sugar utilized, respectively, followed by acid pretreatment of 3.21 mmol H2/g sugar utilized. However, compared with the control （2.70 mmol H2/g sugar utilized）, ultrasonic and ultraviolet pretreatments caused indistinctive effects on H2 production with the values of 2.92 and 2.87 mmol H2/g sugar utilized, respectively. The changes of soluble metabolites composition caused by pretreatment were in accordance with H2-producing behavior. Concretely, more acetate accumulation and less ethanol production were found in pretreated processes, meaning that more reduced nicotinamide adenine dinucleotide （NADH） might be saved and flowed into H2-producing pathways. PCR-DGGE analysis indicated that the pretreatment led to the enrichment of some species, which appeared in large amounts and even dominated the microbial community. Most of the dominated species were affiliated to Enterobacter spp. and Escherichia spp. As another efflcient H2 producer, Clostridium bifermentan was only found in a large quantity after heat pretreatment. This strain might be mainly responsible for better performance of H2 production in this case.展开更多
The production of bio-hydrogen from raw cassava starch via a mixed-culture dark fermentation process was investigated. The production yield of H2 was optimized by adjusting the substrate concentration and the microorg...The production of bio-hydrogen from raw cassava starch via a mixed-culture dark fermentation process was investigated. The production yield of H2 was optimized by adjusting the substrate concentration and the microorganism mixture ratio. A maximum H2 yield of 1.72 mol H2/mol glucose was obtained with a cassava starch concentration of 10 g/L to give a 90% utilization rate. The kinetics of the substrate utilization and of the generation of both hydrogen and volatile fatty acids were also investigated. The substrate utilization follows pseudo first order reaction kinetics, whereas the production of both H2 and the VFAs correlate with the Gompertz equation. These results show that cassava is a good candidate for the production of biohydrogen.展开更多
To study the structure of microbial communities in the biological hydrogen produc-tion reactor and determine the ecological function of hydrogen producing bacteria,anaerobic sludge was obtained from the continuous sti...To study the structure of microbial communities in the biological hydrogen produc-tion reactor and determine the ecological function of hydrogen producing bacteria,anaerobic sludge was obtained from the continuous stirred tank reactor(CSTR)in different periods of time,and the diversity and dynamics of microbial communities were investigated by denaturing gra-dient gel electrophoresis(DGGE).The results of DGGE demonstrated that an obvious shift of microbial population happened from the beginning of star-up to the 28th day,and the ethanol type fermentation was established.After 28 days the structure of microbial community became stable,and the climax community was formed.Comparative analysis of 16S rDNA sequences from reamplifying and sequencing the prominent bands indicated that the dominant population belonged to low G+C Gram-positive bacteria(Clostridium sp.and Ethanologenbacterium sp.),β-proteobacteria(Acidovorax sp.),γ-proteobacteria(Kluyvera sp.),Bacteroides(uncultured bacte-rium SJA-168),and Spirochaetes(uncultured eubacterium E1-K13),respectively.The hydrogen production rate increased obviously with the increase of Ethanologenbacterium sp.,Clostridium sp.and uncultured Spirochaetes after 21 days,meanwhile the succession of ethanol type fer-mentation was formed.Throughout the succession the microbial diversity increased however it decreased after 21 days.Some types of Clostridium sp.Acidovorax sp.,Kluyvera sp.,and Bac-teroides were dominant populations during all periods of time.These special populations were essential for the construction of climax community.Hydrogen production efficiency was de-pendent on both hydrogen producing bacteria and other populations.It implied that the co-metabolism of microbial community played a great role of biohydrogen production in the reactors.展开更多
Hydrogen is an ideal, clean and sustainable energy source for the future because of its high conversion and nonpolluting nature. Biohydrogen production by dark-fermentation appears to have a great potential to be deve...Hydrogen is an ideal, clean and sustainable energy source for the future because of its high conversion and nonpolluting nature. Biohydrogen production by dark-fermentation appears to have a great potential to be developed for practical application. However, one limiting factor affecting the development of hydrogen-production industrialization is that the hydrogen-producing capacity of bacteria is lower, so how to increase bacteria＇ s hydrogen-producing ability will be an urgent issue. In this experiment, 2 mutants, namely UV3 and UV7, were obtained by ultra-violet radiation. They grew and produced hydrogen efficiently on iron-containing medium. The hydrogen evolution of UV3 and UV7 were 2 356. 68 ml/L and 2 219. 62 ml/L at a glucose concentration of 10 g/L, respectively. With wild parent strain Ethanoligenens sp. ZGX4, the hydrogen evolution was 1 806. 02 ml/L under the same conditions. Mutants＇ hydrogen-producing capacities were about 29. 71% and 22.22% higher than that of wild parent strain ZGX4. The maximum H2 production rate by mutants UV3 and UV7 were estimated to be 32.57 mmol H2/g cell h and 31.19 mmol H2/g cell h, respectively, which were 38. 18% and 34. 78% higher than the control （23.57 mmol H：/g cell h）. The abundant products of UV3 and UV7 were ethanol and acetic, which accounted for 95% - 98% of total soluble microbial products. In each case, mutant strains UV3 and UV7 evolved hydrogen at a higher rate than the wild type, showing a possible potential for commercial hydrogen production. Another mutant named UV20＇ was also gained whose main end metabolites were butyric acid and acetic acid. This would provide researched material for a discussion of metabolic pathways of hydrogen-producing bacteria.展开更多
Expanded granular sludge bed （EGSB） reactor and bioaugmentation were employed to investigate biohydrogen production with molasses wastewater. The start-up experiments consisted of two stages. In the first stage （0 ...Expanded granular sludge bed （EGSB） reactor and bioaugmentation were employed to investigate biohydrogen production with molasses wastewater. The start-up experiments consisted of two stages. In the first stage （0 - 24d） seeded with activated sludge, the butyric acid type-fermentation formed when the initial expanding rate, organic loading rate （OLR）, the initial redox potential （ORP） and hydraulic retention time （HRT） were 10%, 10.0 kg COD/（m^3·d）, -215 mV and 6.7 h, respectively. At the beginning of the second stage on day 25, the novel hydrogen-producing fermentative bacterial strain B49 （AF481148 in EMBL） were inoculated into the reactor under the condition of OLR 16. 0 kg COD/（m^3·d）, ORP and HRT about - 139 mV and 6.7 h, respectively, and then the reaction system transformed to ethanol-type fermentation gradually with the increase in OLR. When OLR, ORP and HRT were about 94.3 kg COD/（m^3·d）, -250 mV and 1.7 h, respectively, the system achieved the maximum hydrogen-producing rate of 282.6 mL H2/L reactor·h and hydrogen percentage of 51% -53% in the biogas.展开更多
Molasses wastewater was evaluated as substrate for biohydrogen production by anaerobic fermentation in a novel continuous mixed attached growth reactor ( CMAGR ) with aeration pretreated sludge attached onto granular ...Molasses wastewater was evaluated as substrate for biohydrogen production by anaerobic fermentation in a novel continuous mixed attached growth reactor ( CMAGR ) with aeration pretreated sludge attached onto granular activated carbon under continuous flow condition.It was indicated that the CMAGR system was operated at the conditions of influent COD of 2000～6000mg / L , hydraulic retention time ( HRT ) of 6hand temperature of 35 ℃ , when the pH value and oxidation-reduction potential ( ORP ) ranged from 4.16and-434 mV respectively , stable ethanol-type fermentation was formed with the sum of ethanol and acetate concentration ratio of 89.3%to the total liquid products after 40days operation.The H 2 content in biogas and chemical oxygen demand ( COD ) removal were estimated to be 46.6% and 13% , respectively.It was also investigated that the effects of organic loading rates ( OLRs ) on CMAGR hydrogen production system.It was found that hydrogen production yield increased from 3.72 mmol / hL to 12.51 mmol / hL as OLRs increased from 8 kg / m 3 d to 32 kg / m 3 d.The maximum hydrogen production rate of 12.51mmol / hL at a OLR of 32kg / m 3 d and the maximum hydrogen yield by substrate consumed was 130.57 mmol / mol happened at OLR of 16 kg / m 3 d.Greater pHs appeared to be favour to butyrate production and the maximum of 0.51mol / mol was obtained at pH of 4.14.However , ethanol / acetate ratio was greater than 1.1at pH fluctuated between 3.4 - 3.6and 4.1 - 4.4which indicated that these pHs were favour to ethanol type fermentation.Therefore , the continuous mixed attached growth reactor ( CMAGR ) could be a promising attached growth system for biohydrogen fermentation.展开更多
Microbial electrolysis cell(MEC)is a potential technology to meet the increasing interest in finding new sources of energy that will not harm the environment.MEC is an alternative energy conversion technology for the ...Microbial electrolysis cell(MEC)is a potential technology to meet the increasing interest in finding new sources of energy that will not harm the environment.MEC is an alternative energy conversion technology for the production of biofuels.It is possible to produce hydrogen by fermenting biogenous wastes with hydrogen-producing bacteria.This study investigated the biohydrogen production from co-substrates using electrogenic bacteria such as Escherichia coli,Salmonella bongori,and Shewanella oneidensis in pure culture and as a co-culture,which has the potential to be used as co-substrate in MECs.Briefly,150 mL working-volume reactors were constructed for batch biohydrogen production.The hydrogen production rate(HPR)from the co-substrate was maximum at a ratio of 75:25 g/L with a co-culture of 2.35 mL/(L h).Fabricated a single-chamber membrane-free microelectrolysis cell to evaluate the power density,current density,voltage,HPR,chemical oxygen demand(COD)removal efficiency and Columbic efficiency.Scanning electron microscope(SEM)imaging confirmed the binding of electrogenic bacteria to anode and cathode.The efficiency of electrical conductivity of MEC was analyzed by three different electrodes,namely,nickel,copper and aluminum.The HPR was high using nickel when compared to the other two electrodes.The HPR of a single chamber using a nickel electrode was 2.8 HPR ml/L H_(2) d^(−1) and provided a power density of 17.7 mW/m^(2) at pH 7.This study suggests that the nickel cathode in a single chamber could be a promising sustainable source for stable power generation.展开更多
基金the National Natural Science Foundation of China (Grant No. 50325824)
文摘The effect of substrate concentration ranging from 0 to 300 g/L on fermentative hydrogen production by mixed cultures was investigated in batch tests using glucose as substrate. The experimental results showed that, at 35 and initial pH 7.0, during the fermentative hydrogen production, the hydrogen °C production potential and hydrogen production rate increased with increasing substrate concentration from 0 to 25 g/L. The maximal hydrogen production potential of 426.8 mL and maximal hydrogen production rate of 15.1 mL/h were obtained at the substrate concentration of 25 g/L. The maximal hydrogen yield and the maximal substrate degradation efficiency were respectively 384.3 mL/g glucose and 97.6%, at the substrate concentration of 2 g/L. The modified Logistic model could be used to describe the progress of cumulative hydrogen production in this study successfully. The Han-Levenspiel model could be used to describe the effect of substrate concentration on fermentative hydrogen production rate.
基金the Ministry of Higher Education,Research and Innovation(MoHERI)Oman for their support of this research through TRC block funding Grant no.:BFP/RGP/EBR/22/378。
文摘While reliance on renewable energy resources has become a reality, there is still a need to deploy greener and more sustainable methods in order to achieve sustainable development goals. Indeed, green hydrogen is currently believed to be a reliable solution for global warming and the pollution challenges arising from fossil fuels, making it the resilient fuel of the future. However, the sustainability of green hydrogen technologies is yet to be achieved. In this context, generation of green hydrogen with the aid of deep eutectic solvents(DESs) as green mixtures has been demonstrated as a promising research area. This systematic review article covers green hydrogen generation through water splitting and biomass fermentation when DESs are utilized within the generation process. It also discusses the incorporation of DESs in fuel cell technologies. DESs can play a variety of roles such as solvent, electrolyte, or precursor;colloidal suspension and reaction medium;galvanic replacement, shape-controlling, decoration, or extractive agent;finally oxidant. These roles are relevant to several methods of green hydrogen generation, including electrocatalysis, photocatalysis, and fermentation. As such, it is of utmost importance to screen potential DES formulations and determine how they can function in and contribute throughout the green hydrogen mobility stages. The realization of super green hydrogen generation stands out as a pivotal milestone in our journey towards achieving a more sustainable form of development;DESs have great potential in making this milestone achievable. Overall, incorporating DESs in hydrogen generation constitutes a promising research area and offers potential scalability for green hydrogen production, storage,transport, and utilization.
基金supported by the National Natural Science Foundation of China (No. 30870037, 30970552)the Funding of the National Creative Research Groups (No.50821002)+1 种基金the Aid Program for Science and Technology Innovative Research Team in Higher Educational Instituions of Heilongjiang Province (No. 2010TD10)the Harbin Normal University (No. KJTD2011-2)
文摘Five individual pretreatment methods, including three widely-used protocols （heat, acid and base） and two novel attempts （ultrasonic and ultraviolet）, were conducted in batch tests to compare their effects on mixed microflora to enhance hydrogen （H2） production from corn stover hydrolysate. Experimental results indicated that heat and base pretreatments significantly increased H2 yield with the values of 5.03 and 4.45 mmol H2/g sugar utilized, respectively, followed by acid pretreatment of 3.21 mmol H2/g sugar utilized. However, compared with the control （2.70 mmol H2/g sugar utilized）, ultrasonic and ultraviolet pretreatments caused indistinctive effects on H2 production with the values of 2.92 and 2.87 mmol H2/g sugar utilized, respectively. The changes of soluble metabolites composition caused by pretreatment were in accordance with H2-producing behavior. Concretely, more acetate accumulation and less ethanol production were found in pretreated processes, meaning that more reduced nicotinamide adenine dinucleotide （NADH） might be saved and flowed into H2-producing pathways. PCR-DGGE analysis indicated that the pretreatment led to the enrichment of some species, which appeared in large amounts and even dominated the microbial community. Most of the dominated species were affiliated to Enterobacter spp. and Escherichia spp. As another efflcient H2 producer, Clostridium bifermentan was only found in a large quantity after heat pretreatment. This strain might be mainly responsible for better performance of H2 production in this case.
基金The authors express their thanks for the support from the National Natural Science Foundation of China （Grant No. 21525625）, the National Basic Research Program of China （973 Program, Grant No. 2014CB745100）, the National High Technology Research and Development Program of China （863 Program, Grant No. 2013AA020302）.
文摘The production of bio-hydrogen from raw cassava starch via a mixed-culture dark fermentation process was investigated. The production yield of H2 was optimized by adjusting the substrate concentration and the microorganism mixture ratio. A maximum H2 yield of 1.72 mol H2/mol glucose was obtained with a cassava starch concentration of 10 g/L to give a 90% utilization rate. The kinetics of the substrate utilization and of the generation of both hydrogen and volatile fatty acids were also investigated. The substrate utilization follows pseudo first order reaction kinetics, whereas the production of both H2 and the VFAs correlate with the Gompertz equation. These results show that cassava is a good candidate for the production of biohydrogen.
基金This work was supported by the National Science Foundation for Distinguished Young Scholars(No.50125823)National Natural Science Foundation of China(Grant No.30470054)Key Project of Chinese National Programs for Fundamental Research and Development(No.G2000026402).
文摘To study the structure of microbial communities in the biological hydrogen produc-tion reactor and determine the ecological function of hydrogen producing bacteria,anaerobic sludge was obtained from the continuous stirred tank reactor(CSTR)in different periods of time,and the diversity and dynamics of microbial communities were investigated by denaturing gra-dient gel electrophoresis(DGGE).The results of DGGE demonstrated that an obvious shift of microbial population happened from the beginning of star-up to the 28th day,and the ethanol type fermentation was established.After 28 days the structure of microbial community became stable,and the climax community was formed.Comparative analysis of 16S rDNA sequences from reamplifying and sequencing the prominent bands indicated that the dominant population belonged to low G+C Gram-positive bacteria(Clostridium sp.and Ethanologenbacterium sp.),β-proteobacteria(Acidovorax sp.),γ-proteobacteria(Kluyvera sp.),Bacteroides(uncultured bacte-rium SJA-168),and Spirochaetes(uncultured eubacterium E1-K13),respectively.The hydrogen production rate increased obviously with the increase of Ethanologenbacterium sp.,Clostridium sp.and uncultured Spirochaetes after 21 days,meanwhile the succession of ethanol type fer-mentation was formed.Throughout the succession the microbial diversity increased however it decreased after 21 days.Some types of Clostridium sp.Acidovorax sp.,Kluyvera sp.,and Bac-teroides were dominant populations during all periods of time.These special populations were essential for the construction of climax community.Hydrogen production efficiency was de-pendent on both hydrogen producing bacteria and other populations.It implied that the co-metabolism of microbial community played a great role of biohydrogen production in the reactors.
基金Sponsored by"973"Fundamental Science Program of China(Grant No. G2000026402) and National Natural Science Fund of China (Grant No. 30470054).
文摘Hydrogen is an ideal, clean and sustainable energy source for the future because of its high conversion and nonpolluting nature. Biohydrogen production by dark-fermentation appears to have a great potential to be developed for practical application. However, one limiting factor affecting the development of hydrogen-production industrialization is that the hydrogen-producing capacity of bacteria is lower, so how to increase bacteria＇ s hydrogen-producing ability will be an urgent issue. In this experiment, 2 mutants, namely UV3 and UV7, were obtained by ultra-violet radiation. They grew and produced hydrogen efficiently on iron-containing medium. The hydrogen evolution of UV3 and UV7 were 2 356. 68 ml/L and 2 219. 62 ml/L at a glucose concentration of 10 g/L, respectively. With wild parent strain Ethanoligenens sp. ZGX4, the hydrogen evolution was 1 806. 02 ml/L under the same conditions. Mutants＇ hydrogen-producing capacities were about 29. 71% and 22.22% higher than that of wild parent strain ZGX4. The maximum H2 production rate by mutants UV3 and UV7 were estimated to be 32.57 mmol H2/g cell h and 31.19 mmol H2/g cell h, respectively, which were 38. 18% and 34. 78% higher than the control （23.57 mmol H：/g cell h）. The abundant products of UV3 and UV7 were ethanol and acetic, which accounted for 95% - 98% of total soluble microbial products. In each case, mutant strains UV3 and UV7 evolved hydrogen at a higher rate than the wild type, showing a possible potential for commercial hydrogen production. Another mutant named UV20＇ was also gained whose main end metabolites were butyric acid and acetic acid. This would provide researched material for a discussion of metabolic pathways of hydrogen-producing bacteria.
文摘Expanded granular sludge bed （EGSB） reactor and bioaugmentation were employed to investigate biohydrogen production with molasses wastewater. The start-up experiments consisted of two stages. In the first stage （0 - 24d） seeded with activated sludge, the butyric acid type-fermentation formed when the initial expanding rate, organic loading rate （OLR）, the initial redox potential （ORP） and hydraulic retention time （HRT） were 10%, 10.0 kg COD/（m^3·d）, -215 mV and 6.7 h, respectively. At the beginning of the second stage on day 25, the novel hydrogen-producing fermentative bacterial strain B49 （AF481148 in EMBL） were inoculated into the reactor under the condition of OLR 16. 0 kg COD/（m^3·d）, ORP and HRT about - 139 mV and 6.7 h, respectively, and then the reaction system transformed to ethanol-type fermentation gradually with the increase in OLR. When OLR, ORP and HRT were about 94.3 kg COD/（m^3·d）, -250 mV and 1.7 h, respectively, the system achieved the maximum hydrogen-producing rate of 282.6 mL H2/L reactor·h and hydrogen percentage of 51% -53% in the biogas.
基金support from the National Hi-Tech R&D Program(863 Program)Ministry of Science & Technology,China(2006AA05Z109)+2 种基金Shanghai Science and Technology Bureau(071605122)Shanghai Education Committee(07ZZ156)GRAP09,Northeast Forestry University are gratefully acknowledged
文摘Molasses wastewater was evaluated as substrate for biohydrogen production by anaerobic fermentation in a novel continuous mixed attached growth reactor ( CMAGR ) with aeration pretreated sludge attached onto granular activated carbon under continuous flow condition.It was indicated that the CMAGR system was operated at the conditions of influent COD of 2000～6000mg / L , hydraulic retention time ( HRT ) of 6hand temperature of 35 ℃ , when the pH value and oxidation-reduction potential ( ORP ) ranged from 4.16and-434 mV respectively , stable ethanol-type fermentation was formed with the sum of ethanol and acetate concentration ratio of 89.3%to the total liquid products after 40days operation.The H 2 content in biogas and chemical oxygen demand ( COD ) removal were estimated to be 46.6% and 13% , respectively.It was also investigated that the effects of organic loading rates ( OLRs ) on CMAGR hydrogen production system.It was found that hydrogen production yield increased from 3.72 mmol / hL to 12.51 mmol / hL as OLRs increased from 8 kg / m 3 d to 32 kg / m 3 d.The maximum hydrogen production rate of 12.51mmol / hL at a OLR of 32kg / m 3 d and the maximum hydrogen yield by substrate consumed was 130.57 mmol / mol happened at OLR of 16 kg / m 3 d.Greater pHs appeared to be favour to butyrate production and the maximum of 0.51mol / mol was obtained at pH of 4.14.However , ethanol / acetate ratio was greater than 1.1at pH fluctuated between 3.4 - 3.6and 4.1 - 4.4which indicated that these pHs were favour to ethanol type fermentation.Therefore , the continuous mixed attached growth reactor ( CMAGR ) could be a promising attached growth system for biohydrogen fermentation.
文摘Microbial electrolysis cell(MEC)is a potential technology to meet the increasing interest in finding new sources of energy that will not harm the environment.MEC is an alternative energy conversion technology for the production of biofuels.It is possible to produce hydrogen by fermenting biogenous wastes with hydrogen-producing bacteria.This study investigated the biohydrogen production from co-substrates using electrogenic bacteria such as Escherichia coli,Salmonella bongori,and Shewanella oneidensis in pure culture and as a co-culture,which has the potential to be used as co-substrate in MECs.Briefly,150 mL working-volume reactors were constructed for batch biohydrogen production.The hydrogen production rate(HPR)from the co-substrate was maximum at a ratio of 75:25 g/L with a co-culture of 2.35 mL/(L h).Fabricated a single-chamber membrane-free microelectrolysis cell to evaluate the power density,current density,voltage,HPR,chemical oxygen demand(COD)removal efficiency and Columbic efficiency.Scanning electron microscope(SEM)imaging confirmed the binding of electrogenic bacteria to anode and cathode.The efficiency of electrical conductivity of MEC was analyzed by three different electrodes,namely,nickel,copper and aluminum.The HPR was high using nickel when compared to the other two electrodes.The HPR of a single chamber using a nickel electrode was 2.8 HPR ml/L H_(2) d^(−1) and provided a power density of 17.7 mW/m^(2) at pH 7.This study suggests that the nickel cathode in a single chamber could be a promising sustainable source for stable power generation.
