| Effects of different initial pH values（4.0, 5.5, 7.0, 8.5, 10.0 and 11.5） on co-production of hydrogen and methane from pretreated cornstalk and sewage sludge were investigated in batch experiments. Results showed significant differences among the hydrogen yields under different initial pH values. At initial pH of 5.5, the maximal hydrogen yield of 32.0 mL·g-1-VS was obtained, and the total energy produced was 9.16 kJ·g-1-VS. At initial pH of 11.5, the maximum methane yield of 265.7 mL·g-1-VS and maximum total energy of 9.36 kJ·g-1-VS were obtained. Hydrogen fermentation mainly consumed the soluble carbohydrates produced through pretreatment of cornstalk. Methane fermentation mainly utilized fatty acids produced in hydrogen fermentation stage. The total energy produced in the two-stage fermentation process was 1.4~1.6 times of that in the single-stage methane fermentation. |
