The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Fang Zhang - One of the best experts on this subject based on the ideXlab platform.
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microbial dynamics of the extreme thermophilic 70 c mixed culture for Hydrogen production in a chemostat
International Journal of Hydrogen Energy, 2016Co-Authors: Fang Zhang, Jing-hua Yang, Kun Dai, Fa-ming Gao, Zhaowei Ding, Longgang Wang, Raymond J. ZengAbstract:Abstract Most studies of mixed culture fermentation for Hydrogen production focus on the metabolite distribution under different operational conditions. While, the corresponding microbial dynamics research is limited. The aim of this work was to reveal the microbial community dynamics of extreme-thermophilic mixed culture enriched in a chemostat for Hydrogen production with the combining molecular tools of denaturing gradient gel electrophoresis (DGGE), Illumina Miseq high-throughput sequencing platform, and 16S rRNA clone library sequencing. The analyzed results showed that the genera of Caldanaerobius, Caldicellulosiruptor and/or Thermoanaerobacter dominated the bacteria. While archaea were not detected even by Illumina Miseq high-throughput sequencing. The effects of Hydrogen Partial Pressure or pH increasing from 5.5 to 7.0 on the microbial communities were not notably, and genera of Caldicellulosiruptor and Thermoanaerobacter were the dominants. High Hydrogen yield in this chemostat was attributed to the enrichment of Caldicellulosiruptor . While Caldanaerobius dominated the bacteria communities as pH decreased to 4.5. Caldanaerobius and Thermoanaerobacter dominated at high influent glucose concentrations. Thereby, it clearly indicated that the microbial dynamics shall be considered when analyzing the extreme-thermophilic mixed culture fermentation in the future.
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Characterization of microbial compositions in a thermophilic chemostat of mixed culture fermentation
Applied Microbiology and Biotechnology, 2015Co-Authors: Fang Zhang, Jing-hua Yang, Kun Dai, Yun Chen, Fa-ming Gao, Raymond J. ZengAbstract:The microbial community compositions of a chemostat enriched in a thermophilic (55 °C) mixed culture fermentation (MCF) for Hydrogen production under different operational conditions were revealed in this work by integrating denaturing gradient gel electrophoresis (DGGE), Illumina Miseq high-throughput sequencing, and 16S rRNA clone library sequencing. The results showed that the community structure of the enriched cultures was relatively simple. Clones close to the genera of Thermoanaerobacter and/or Bacillus mainly dominated the bacteria. And homoacetogens and archaea were washed out and not detected even by Illumina Miseq high-throughput sequencing which supported the benefit for Hydrogen production. On the other hand, the results revealed that the metabolic shift was clearly associated with the change of dominated bacterial groups. The effects of Hydrogen Partial Pressure (PH2) and pH from 4.0 to 5.5 on the microbial compositions were not notable and Thermoanaerobacter was dominant, thus, the metabolites were also not changed. While Bacillus, Thermoanaerobacter and Propionispora hippei dominated the bacteria communities at neutral pH, or Bacillus and Thermoanaerobacter dominated at high influent glucose concentrations, consequently the main metabolites shifted to acetate, ethanol, propionate, or lactate. Thereby, the effect of microbial composition on the metabolite distribution and shift shall be considered when modeling thermophilic MCF in the future.
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stable acetate production in extreme thermophilic 70 c mixed culture fermentation by selective enrichment of Hydrogenotrophic methanogens
Scientific Reports, 2015Co-Authors: Fang Zhang, Yan Zhang, Jing Ding, Mark C M Van Loosdrecht, Raymond J. ZengAbstract:The control of metabolite production is difficult in mixed culture fermentation. This is particularly related to Hydrogen inhibition. In this work, Hydrogenotrophic methanogens were selectively enriched to reduce the Hydrogen Partial Pressure and to realize efficient acetate production in extreme-thermophilic (706C) mixed culture fermentation. The continuous stirred tank reactor (CSTR) was stable operated during 100 days, in which acetate accounted for more than 90% of metabolites in liquid solutions. The yields of acetate, methane and biomass in CSTR were 1.5 ± 0.06, 1.0 ± 0.13 and 0.4 ± 0.05 mol/mol glucose, respectively, close to the theoretical expected values. The CSTR effluent was stable and no further conversion occurred when incubated for 14 days in a batch reactor. In fed-batch experiments, acetate could be produced up to 34.4 g/L, significantly higher than observed in common Hydrogen producing fermentations. Acetate also accounted for more than 90% of soluble products formed in these fed-batch fermentations. The microbial community analysis revealed Hydrogenotrophic methanogens (mainly Methanothermobacter thermautotrophicus and Methanobacterium thermoaggregans) as 98% of Archaea, confirming that high temperature will select Hydrogenotrophic methanogens over aceticlastic methanogens effectively. This work demonstrated a potential application to effectively produce acetate as a value chemical and methane as an energy gas together via mixed culture fermentation.
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the chemostat study of metabolic distribution in extreme thermophilic 70 c mixed culture fermentation
Applied Microbiology and Biotechnology, 2014Co-Authors: Fang Zhang, Kun Dai, Yun Chen, Raymond J. ZengAbstract:The effects of pH, Hydrogen Partial Pressure (PH2), and influent glucose concentration on the metabolic distribution in chemostat were investigated in this work in extreme-thermophilic mixed culture fermentation (MCF) process. The results showed that acetate, ethanol, and Hydrogen were the main metabolites. A shift of ethanol to acetate and Hydrogen was observed as pH increasing from 4.0 to 7.0 or PH2 decreasing from 0.64 to 0.05 atm. The maximum Hydrogen yield was 3.16 ± 0.16 mol/mol glucose at PH2 0.05 atm. Lactate was only accumulated at low pH or high influent glucose concentration, while others such as butyrate and formate were rather low. Thermodynamic analysis illustrated that a mixture of acetate, ethanol, and/or lactate was essential for Hydrogen production in extreme-thermophilic MCF. The Hydrogen-producing rate was also calculated, and the maximum value was 2.2 ± 0.1 L/(L-reactor/day) at PH2 0.05 atm. Except Hydrogen, other metabolites, such as liquid fatty acids and biofuels, could also be the producing targets in extreme-thermophilic MCF.
Raymond J. Zeng - One of the best experts on this subject based on the ideXlab platform.
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microbial dynamics of the extreme thermophilic 70 c mixed culture for Hydrogen production in a chemostat
International Journal of Hydrogen Energy, 2016Co-Authors: Fang Zhang, Jing-hua Yang, Kun Dai, Fa-ming Gao, Zhaowei Ding, Longgang Wang, Raymond J. ZengAbstract:Abstract Most studies of mixed culture fermentation for Hydrogen production focus on the metabolite distribution under different operational conditions. While, the corresponding microbial dynamics research is limited. The aim of this work was to reveal the microbial community dynamics of extreme-thermophilic mixed culture enriched in a chemostat for Hydrogen production with the combining molecular tools of denaturing gradient gel electrophoresis (DGGE), Illumina Miseq high-throughput sequencing platform, and 16S rRNA clone library sequencing. The analyzed results showed that the genera of Caldanaerobius, Caldicellulosiruptor and/or Thermoanaerobacter dominated the bacteria. While archaea were not detected even by Illumina Miseq high-throughput sequencing. The effects of Hydrogen Partial Pressure or pH increasing from 5.5 to 7.0 on the microbial communities were not notably, and genera of Caldicellulosiruptor and Thermoanaerobacter were the dominants. High Hydrogen yield in this chemostat was attributed to the enrichment of Caldicellulosiruptor . While Caldanaerobius dominated the bacteria communities as pH decreased to 4.5. Caldanaerobius and Thermoanaerobacter dominated at high influent glucose concentrations. Thereby, it clearly indicated that the microbial dynamics shall be considered when analyzing the extreme-thermophilic mixed culture fermentation in the future.
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Characterization of microbial compositions in a thermophilic chemostat of mixed culture fermentation
Applied Microbiology and Biotechnology, 2015Co-Authors: Fang Zhang, Jing-hua Yang, Kun Dai, Yun Chen, Fa-ming Gao, Raymond J. ZengAbstract:The microbial community compositions of a chemostat enriched in a thermophilic (55 °C) mixed culture fermentation (MCF) for Hydrogen production under different operational conditions were revealed in this work by integrating denaturing gradient gel electrophoresis (DGGE), Illumina Miseq high-throughput sequencing, and 16S rRNA clone library sequencing. The results showed that the community structure of the enriched cultures was relatively simple. Clones close to the genera of Thermoanaerobacter and/or Bacillus mainly dominated the bacteria. And homoacetogens and archaea were washed out and not detected even by Illumina Miseq high-throughput sequencing which supported the benefit for Hydrogen production. On the other hand, the results revealed that the metabolic shift was clearly associated with the change of dominated bacterial groups. The effects of Hydrogen Partial Pressure (PH2) and pH from 4.0 to 5.5 on the microbial compositions were not notable and Thermoanaerobacter was dominant, thus, the metabolites were also not changed. While Bacillus, Thermoanaerobacter and Propionispora hippei dominated the bacteria communities at neutral pH, or Bacillus and Thermoanaerobacter dominated at high influent glucose concentrations, consequently the main metabolites shifted to acetate, ethanol, propionate, or lactate. Thereby, the effect of microbial composition on the metabolite distribution and shift shall be considered when modeling thermophilic MCF in the future.
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stable acetate production in extreme thermophilic 70 c mixed culture fermentation by selective enrichment of Hydrogenotrophic methanogens
Scientific Reports, 2015Co-Authors: Fang Zhang, Yan Zhang, Jing Ding, Mark C M Van Loosdrecht, Raymond J. ZengAbstract:The control of metabolite production is difficult in mixed culture fermentation. This is particularly related to Hydrogen inhibition. In this work, Hydrogenotrophic methanogens were selectively enriched to reduce the Hydrogen Partial Pressure and to realize efficient acetate production in extreme-thermophilic (706C) mixed culture fermentation. The continuous stirred tank reactor (CSTR) was stable operated during 100 days, in which acetate accounted for more than 90% of metabolites in liquid solutions. The yields of acetate, methane and biomass in CSTR were 1.5 ± 0.06, 1.0 ± 0.13 and 0.4 ± 0.05 mol/mol glucose, respectively, close to the theoretical expected values. The CSTR effluent was stable and no further conversion occurred when incubated for 14 days in a batch reactor. In fed-batch experiments, acetate could be produced up to 34.4 g/L, significantly higher than observed in common Hydrogen producing fermentations. Acetate also accounted for more than 90% of soluble products formed in these fed-batch fermentations. The microbial community analysis revealed Hydrogenotrophic methanogens (mainly Methanothermobacter thermautotrophicus and Methanobacterium thermoaggregans) as 98% of Archaea, confirming that high temperature will select Hydrogenotrophic methanogens over aceticlastic methanogens effectively. This work demonstrated a potential application to effectively produce acetate as a value chemical and methane as an energy gas together via mixed culture fermentation.
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the chemostat study of metabolic distribution in extreme thermophilic 70 c mixed culture fermentation
Applied Microbiology and Biotechnology, 2014Co-Authors: Fang Zhang, Kun Dai, Yun Chen, Raymond J. ZengAbstract:The effects of pH, Hydrogen Partial Pressure (PH2), and influent glucose concentration on the metabolic distribution in chemostat were investigated in this work in extreme-thermophilic mixed culture fermentation (MCF) process. The results showed that acetate, ethanol, and Hydrogen were the main metabolites. A shift of ethanol to acetate and Hydrogen was observed as pH increasing from 4.0 to 7.0 or PH2 decreasing from 0.64 to 0.05 atm. The maximum Hydrogen yield was 3.16 ± 0.16 mol/mol glucose at PH2 0.05 atm. Lactate was only accumulated at low pH or high influent glucose concentration, while others such as butyrate and formate were rather low. Thermodynamic analysis illustrated that a mixture of acetate, ethanol, and/or lactate was essential for Hydrogen production in extreme-thermophilic MCF. The Hydrogen-producing rate was also calculated, and the maximum value was 2.2 ± 0.1 L/(L-reactor/day) at PH2 0.05 atm. Except Hydrogen, other metabolites, such as liquid fatty acids and biofuels, could also be the producing targets in extreme-thermophilic MCF.
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homoacetogenesis as the alternative pathway for h2 sink during thermophilic anaerobic degradation of butyrate under suppressed methanogenesis
Water Research, 2007Co-Authors: Vilailuck Siriwongrungson, Raymond J. Zeng, Irini AngelidakiAbstract:Abstract Butyrate degradation for Hydrogen production under conditions suppressing methanogenesis was evaluated in continuously fed-tank reactors operated at 55 °C and started up with digested manure as inoculum. This study shows that the reaction of butyrate degradation to acetate and Hydrogen could happen when gas sparging was applied. Gas sparging was very important for reducing Hydrogen Partial Pressure and made the reaction thermodynamically possible. Almost no Hydrogen or methane (methane production was prevented by the addition of 2-bromoethane-sulfonic acid) was detected, indicating that the H 2 produced from butyrate oxidation was consumed in a subsequent step. It was found by isotope experiments that Hydrogen produced from butyrate degradation reacted immediately with CO 2 to form acetate via homoacetogenesis. When CO 2 /HCO 3 − was not provided in the system, butyrate degradation was no longer possible and butyrate-degrading cultures were washed out. It was furthermore found that the microorganisms responsible for homoacetogenesis were likely present in normal anaerobic environments, such as biogas reactors.
John Adjaye - One of the best experts on this subject based on the ideXlab platform.
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effects of Hydrogen Partial Pressure on hydrotreating of heavy gas oil derived from oil sands bitumen experimental and kinetics
Energy & Fuels, 2010Co-Authors: M Mapiour, V. Sundaramurthy, Ajay Kumar Dalai, John AdjayeAbstract:The effect of Hydrogen Partial Pressure (H2 pp) on hydrotreating conversions, feed vaporization, H2 dissolution, and H2 consumption was studied in a micro trickle-bed reactor, using a commercial NiMo/γ-Al2O3 catalyst. Heavy gas oil (HGO) from Athabasca bitumen was used as feed. The H2 pp level was set inside the reactor by means of manipulating other operating variables, namely, H2 purity, Pressure, gas/oil ratio, liquid hourly space velocity (LHSV), and temperature. Their ranges were as follows: 75−100 vol % (with the rest methane), 7−11 MPa, 400−1200, 0.65−2 h−1, and 360−400 °C, respectively. HYSYS was used to determine the inlet and outlet H2 pp. The results show that hydrodenitrogenation (HDN) and hydrodearomatization (HDA) are significantly more affected by H2 pp than hydrodesulfurization (HDS), with HDN being the most affected. Moreover, it was observed that H2 dissolution and H2 consumption increase with increasing H2 pp. No clear trend was observed for the effect of H2 pp on feed vaporization. Kin...
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effect of Hydrogen purity on hydroprocessing of heavy gas oil derived from oil sands bitumen
Energy & Fuels, 2009Co-Authors: M Mapiour, V. Sundaramurthy, Ajay Kumar Dalai, John AdjayeAbstract:The effect of Hydrogen purity on hydroprocessing of heavy gas oil (HGO) was studied in a trickle bed reactor over a commercial Ni−Mo/γ-alumina catalyst. Methane was used as a diluent for the Hydrogen stream, and its effect on the catalyst performance was compared to that of helium, which is inert toward the catalyst. Furthermore, a deactivation study was conducted over a period of 66 days, during which the catalyst was subjected to H2 purity ranging from 95 to 75% (with the rest methane); no significant deterioration in the hydroprocessing activities of the catalyst was observed. Therefore, it was concluded that methane was inert toward a commercial Ni−Mo/γ-alumina catalyst. However, its presence resulted in Hydrogen Partial Pressure reduction, which in turn led to a decrease in hydrodesulphurization (HDS), hydrodenitrogenation (HDN), hydrodearomatization (HDA) conversions. This reduction can be offset by increasing the total Pressure of the system. HDS, HDN, HDA, and mild hydrocracking (MHC) conversions ...
Serge Hiligsmann - One of the best experts on this subject based on the ideXlab platform.
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investigation of the links between mass transfer conditions dissolved Hydrogen concentration and bioHydrogen production by the pure strain clostridium butyricum cwbi1009
Biochemical Engineering Journal, 2015Co-Authors: Laurent Beckers, Christopher Hamilton, Julien Masset, Philippe Thonart, Frank Delvigne, Dominique Toye, Michel Crine, Serge HiligsmannAbstract:Abstract Fermentative Hydrogen production has often been described as inhibited by its own gas production. In this work, Hydrogen production by Clostridium butyricum was investigated in batch Biochemical Hydrogen Potential (BHP) tests and in a 2.5 L anaerobic sequenced batch reactor (AnSBR) under different operating conditions regarding liquid-to-gas mass transfer. Through the addition of both stirring up to 400 rpm and nitrogen sparging, the yields were enhanced from 1.6 to 3.1 molH2 molglucose−1 and the maximum Hydrogen production rates from 140 to 278 mL h−1. These original results were achieved with a pure Clostridium strain. They showed that Hydrogen production was improved by a higher liquid-to-gas Hydrogen transfer resulting in a lower dissolved Hydrogen concentration in the culture medium and therefore in a lower bacterial inhibition. In addition, bioHydrogen partitioning between the gas and the liquid phase did not conform to Henry’s Law due to critical supersaturation phenomena up to seven-fold higher than the equilibrium conditions. Therefore, dissolved Hydrogen concentration should be systematically measured instead of the headspace Hydrogen Partial Pressure. A model was proposed to correlate H2 production yield and rate by the pure C. butyricum strain CWBI1009 with mass transfer coefficient KLa.
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effects of Hydrogen Partial Pressure on fermentative bioHydrogen production by a chemotropic clostridium bacterium in a new horizontal rotating cylinder reactor
Energy Procedia, 2012Co-Authors: Laurent Beckers, Serge Hiligsmann, Christopher Hamilton, Julien Masset, Philippe ThonartAbstract:Abstract In order to produce fermentative bioHydrogen at high yields and production rates, efficient bioreactors have to be designed. A new reactor called anaerobic biodisc reactor allowed the production of bioHydrogen from glucose with the selected Clostridium sp. strain at high yields (2.49 molH2·molglucose-1) and production rates (598 mlH2 medium h-1). The bacteria were fixed on a rotating support enabling efficient gas transfer from the liquid to the phase. It allowed the metabolism of the bacteria to produce more Hydrogen. Moreover, an increase of the total Pressure 0.18 bar lowered the yields of 19.5% while a decrease of 0.11 bar increased the yields of 7%. Our work concludes on the importance of providing good liquid to gas transfers in the bioHydrogen-producing reactors.
M Mapiour - One of the best experts on this subject based on the ideXlab platform.
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effects of Hydrogen Partial Pressure on hydrotreating of heavy gas oil derived from oil sands bitumen experimental and kinetics
Energy & Fuels, 2010Co-Authors: M Mapiour, V. Sundaramurthy, Ajay Kumar Dalai, John AdjayeAbstract:The effect of Hydrogen Partial Pressure (H2 pp) on hydrotreating conversions, feed vaporization, H2 dissolution, and H2 consumption was studied in a micro trickle-bed reactor, using a commercial NiMo/γ-Al2O3 catalyst. Heavy gas oil (HGO) from Athabasca bitumen was used as feed. The H2 pp level was set inside the reactor by means of manipulating other operating variables, namely, H2 purity, Pressure, gas/oil ratio, liquid hourly space velocity (LHSV), and temperature. Their ranges were as follows: 75−100 vol % (with the rest methane), 7−11 MPa, 400−1200, 0.65−2 h−1, and 360−400 °C, respectively. HYSYS was used to determine the inlet and outlet H2 pp. The results show that hydrodenitrogenation (HDN) and hydrodearomatization (HDA) are significantly more affected by H2 pp than hydrodesulfurization (HDS), with HDN being the most affected. Moreover, it was observed that H2 dissolution and H2 consumption increase with increasing H2 pp. No clear trend was observed for the effect of H2 pp on feed vaporization. Kin...
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effect of Hydrogen purity on hydroprocessing of heavy gas oil derived from oil sands bitumen
Energy & Fuels, 2009Co-Authors: M Mapiour, V. Sundaramurthy, Ajay Kumar Dalai, John AdjayeAbstract:The effect of Hydrogen purity on hydroprocessing of heavy gas oil (HGO) was studied in a trickle bed reactor over a commercial Ni−Mo/γ-alumina catalyst. Methane was used as a diluent for the Hydrogen stream, and its effect on the catalyst performance was compared to that of helium, which is inert toward the catalyst. Furthermore, a deactivation study was conducted over a period of 66 days, during which the catalyst was subjected to H2 purity ranging from 95 to 75% (with the rest methane); no significant deterioration in the hydroprocessing activities of the catalyst was observed. Therefore, it was concluded that methane was inert toward a commercial Ni−Mo/γ-alumina catalyst. However, its presence resulted in Hydrogen Partial Pressure reduction, which in turn led to a decrease in hydrodesulphurization (HDS), hydrodenitrogenation (HDN), hydrodearomatization (HDA) conversions. This reduction can be offset by increasing the total Pressure of the system. HDS, HDN, HDA, and mild hydrocracking (MHC) conversions ...
