Biohydrogen production from cornstalk wastes by anaerobic fermentation with activated sludge

An anaerobic fermentation process to produce hydrogen from cornstalk wastes was systematically investigated in this work. Batch experiments numbered series I, II and III were designed to investigate the effects of acid pretreatment, enzymatic hydrolysis (enzymatic temperature, enzymatic time and enzymatic pH) on hydrogen production by using the natural sludge as inoculant. A maximum cumulative H2 yield of 126.22 ml g−1-CS (Cornstalk, or 146.94 ml g−1-TS, Total Solid) and an average H2 production rate of 9.58 ml g−1-CS h−1 were obtained from fermentation cornstalk with a concentration of 20 g/L and an initial pH of 7.0 at 36 °C through an optimal pretreatment process. The optimal process was that the substrate was soaked with an HCl concentration of 0.6 wt% at 90 °C for 2 h, and subsequently enzymatic hydrolysis for 72 h at 50 °C and pH 4.8 before fermentation. The biogas consisted of only H2 and CO2. In addition, the fermentation system was the typical ethanol-type fermentation according to ethanol and acetate as the main liquid by-products.