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: Facultative anaerobes play important roles in H 2 production by biological routes. In the present study, a comprehensive insight on the importance of formate lyase in H 2 production by facultative microorganisms has been focused. Structural details of formate hydrogen lyase reveal the involvement of two enzymes, formate dehydrogenase H (FdhH) and hydrogenase (Hyd) along with electron carriers. The monocistronic fdhF gene codes for the functional formate dehydrogenase H. Functionality of these complexes are dependent on maturation system governed by FDH-D and FDH-E. The overall transcription of FHL complex is governed by protein encoded by fhlA gene. Under anaerobic condition, the pyruvate gets cleave into acetyl-CoA and formate by pyruvate-formate-lyase (PFL). The transporter proteins FocA and FocB helps in transporting formate. During dark fermentation , the physicoechemical parameters such as pH, HRTs, partial pressure play a crucial role in influencing formate degradation to molecular H 2 .International Journal of Hydrogen Energy 06/2015; DOI:10.1016/j.ijhydene.2015.05.076 · 2.93 Impact Factor
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ABSTRACT: A new anaerobic alkaliphilic H2-producer was isolated from a serpentinite-hosted ecosystem.•16S rDNA sequence analysis of strain PROH2 revealed its assignment to a novel Clostridium species.•The maximum H2 productions were obtained at 37 °C, initial pH 9.5 and 2 g/L of glucose.•The isolate is a good candidate for H2 production under alkaline conditions due to its high H2 yield.•It is the first anaerobic microorganism producing H2 at both high pH and low salinity.International Journal of Hydrogen Energy 11/2014; 39. DOI:10.1016/j.ijhydene.2014.09.111 · 2.93 Impact Factor
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ABSTRACT: Biohydrogen production from starch wastewater industry via an up-flow anaerobic staged reactor (UASR) was investigated. The reactor was operated at a hydraulic retention time (HRT) of 0.28 d, and different food to micro-organisms ratios (F/M) of 0.5, 0.9, 1.4, 1.9 and 2.8 g-COD/g-VSS d. Peak hydrogen production rate (HPR) of 246 mmol-H2/L d was observed at F/M of 1.4 g-COD/g-VSS d. Artificial neural network (ANN) with a three layers feed-forward back-propagation (3-8-4-1) was developed to predict the fermentation of biohydrogen production. The network used the default Levenberg-Marquardt algorithm for training. Network inputs were organic loading rate (OLR) (g-COD/L d), pH and volatile suspended solids (VSS) yield (mg-VSS/g-starch). Network output was HPR (mmol-H2/L d). It is observed that, the output tracks the targets very well for training (R2-value= 0.945), validation (R2-value=0.652) and testing (R2-value=0.791). These values can be equivalent to a total response of R2-value= 0.849. In this case, the network response is acceptable, and simulation results can be used as a black-box model for entering new inputs.