Biohydrogen production as a function of pH and substrate concentration.
ABSTRACT The conversion of organics in wastewaters into hydrogen gas could serve the dual role of renewable energy production and waste reduction. The chemical energy in a sucrose rich synthetic wastewater was recovered as hydrogen gas in this study. Using fractional factorial design batch experiments, the effect of varying pH (4.5-7.5) and substrate concentration (1.5-44.8 g COD/L) and their interaction on hydrogen gas production were tested. Mixed bacterial cultures obtained from a compost pile, a potato field, and a soybean field were heated to inhibit hydrogen-consuming methanogens and to enrich sporeforming, hydrogen-producing acidogens. It was determined that the highest rate (74.7 mL H2/(L*h)) of hydrogen production occurred at a pH of 5.5 and a substrate concentration of 7.5 g COD/Lwith a conversion efficiency of 38.9 mL H2/(g COD/L). The highest conversion efficiency was 46.6 mL H2/(g COD/L).
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ABSTRACT: This study evaluated the use of an anaerobic packed-bed reactor for hydrogen production at different hydraulic retention times (HRT) (1-8 h). Two reactors filled with expanded clay and fed with glucose (3136-3875 mg L(-1)) were operated at different total upflow velocities: 0.30 cm s(-1) (R030) and 0.60 cm s(-1) (R060). The effluent pH of the reactors was maintained between 4 and 5 by adding NaHCO3 and HCl solutions. It was observed a maximum hydrogen production rate of 0.92 L H2 h(-1) L(-1) in R030 at HRT of 1 h. Furthermore, the highest hydrogen yield of 2.39 mol H2 mol(-1) glucose was obtained in R060. No clear trend was observed by doubling the upflow velocities at this experiment. High ethanol production was also observed, indicating that the ethanol-pathway prevailed throughout the experiment.BioMed Research International 01/2014; 2014:921291. · 2.71 Impact Factor
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ABSTRACT: In this study, characteristics of biological hydrogen production and microbial distribution were investigated with the wastewater of Tofu manufacturing process. Comparison of hydrogen production was conducted with acid or base pre-treatment of the wastewater. Maximum hydrogen production was acquired with combination of heat and acid treatment. Hydrogen production () and maximum hydrogen production rate () was calculated 661.01 mL and 12.21 mL/g dry wt biomass/hr from the modified Gompartz equation. Most of microbial community was analyzed as Streptococcus sp. from PCR-DGGE experiment of 16S rDNA. It was concluded that most significant microorganism for hydrogen production was Streptococcus gallolyticus sub sp. in this experiment.Journal of Korean Society of Environmental Engineers. 01/2009; 31(2).
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ABSTRACT: Fermentative hydrogen production is a promising technology for garneting renewable and clean energy from renewable and waste resources. We isolated hydrogen producing bacteria from activated sludge, and profiled their fermentative functions using 16S rRNA gene-directed PCR-denaturing gradient gel electrophoresis (DGGE), clone library and heterotrophic plate isolation. Three individual hydrogen producers, which harboured the [FeFe] hydrogenase gene were isolated and identified by 16S rDNA sequence, and further physiologically characterised for the first time as Clostridium sp. (W1), Clostridium butyricum (W4) and Clostridium butyricum (W5). The C. butyricum W5 demonstrated the best fermentative performance for hydrogen production and was used as working strain throughout this study. We experimentally identified the suitable operating parameters, including carbon and nitrogen sources, pH, temperature and inoculum size. The putative [FeFe] hydrogenase gene family structure of C. butyricum W5 was also described. Finally, the changes in [FeFe] hydrogenase mRNA expression of C. butyricum W5 during fermentation were monitored, using quantitative real-time Reverse Transcriptase PCR. Statistical analysis showed that both the [FeFe] hydrogenase mRNA expression level and cell growth have a positive relationship with hydrogen production.