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).

Microbiological and engineering aspects of biohydrogen production

“…For example, one study showed that both hydrogen yield and production rate increased with increasing sucrose up to moderate OLR (5 to 20 g COD/l); however both values decreased when the substrate concentration reached 30 g COD/l [78]. Similar results have been observed in other studies, although inhibition occurred at different substrate concentrations [22,83]. These results suggest that elevated substrate loadings have a toxic effect on the bacteria.…”

“…from the genus Clostridium) generate gas in the exponential growth phase, and then the metabolism shifts from H 2 /acid production to solventogenesis when the culture reaches stationary growth phase [20,21]. Poor hydrogen yields have also been linked to high hydrogen partial pressure, high substrate concentration, low iron concentration, and/or low pH [20,22,23,24]. Current maximum hydrogen yields obtained do not make the fermentative process an attractive one from an economic point of view when compared to conventional reforming techniques.…”

Peer Reviewed: Extracting Hydrogen and Electricity from Renewable Resources

“…While a conversion efficiency of 33% is theoretically possible for hydrogen production from glucose, only half of this is usually obtained under batch and continuous fermentation conditions (17)(18)(19) …”

Application of artificial neural networks for modeling of biohydrogen production

“…Some studies investigated the combined effect of two variables such as pH and substrate concentrations [5,6], temperature and pressure release methods [7], and pH and sulfate concentration [8] on the biohydrogen production process. Ginkel and Sung [5] tested the effect of varying pH (4.5e7.5) and substrate concentration (1.5e44.8 g COD/L) and Abbreviations: ADM1, anaerobic digestion model No.…”

“…Some studies investigated the combined effect of two variables such as pH and substrate concentrations [5,6], temperature and pressure release methods [7], and pH and sulfate concentration [8] on the biohydrogen production process. Ginkel and Sung [5] tested the effect of varying pH (4.5e7.5) and substrate concentration (1.5e44.8 g COD/L) and Abbreviations: ADM1, anaerobic digestion model No. 1; ADS, anaerobic digester sludge; ANN, artificial neural network; APE, average percentage error; COD, chemical oxygen demand; HRT, hydraulic retention time; MAE, mean absolute error; MSE, mean square error; UASB, upflow anaerobic sludge blanket.their interaction on hydrogen production in batch tests using compost as the seed microflora and sucrose as the substrate.…”