Optimization of biohydrogen production from soybean straw using anaerobic mixed bacteria

In this study, batch experiments were carried out to produce biohydrogen from soybean straw after pretreatment using anaerobic mixed bacteria at 35 °C. The effects of acid (HCl), alkali (NaOH), hydrogen peroxide, acid peroxide and alkaline peroxide pretreatments on the cellulosic biomass of soybean straw were studied. Furthermore, the effects of different pretreatment on hydrogen production, together with their corresponding degradation efficiencies for the total reducing sugar (TRS) and metabolites were investigated. The results showed that 4% HCl was the best choice for the pretreatment of soybean straw. Array testing strategy (L9(34)) was applied to design the experiments and analyze the effects of inoculum, initial pH and ferrous iron and nickel concentrations on fermentative hydrogen production. The results showed that hydrogen yield was significantly enhanced by optimizing environmental factors. A maximum cumulative hydrogen yield of 60.2 mL/g-dry soybean straw was achieved, which was approximately 11-fold greater than that in raw soybean straw.