Hydrogen fermentation of organic municipal wastes

Hydrogen gas is recognized as a promising energy resource in the future. Microbial hydrogen fermentation would be an attractive process for hydrogen recovery. In particular, hydrogen production using fermentative bacteria has some advantages such as a high rate of hydrogen production without light. In this study, the hydrogen production from organic wastes was investigated using batch experiments. Bean curd manufacturing waste, rice bran and wheat bran were used as the organic wastes. The effects of solid concentration on the hydrogen production potential and the characteristics of substrate decomposition were investigated. The percentages of hydrogen in the produced gas were between 54–78%, 43–68% and 42–72% for bean curd manufacturing waste, ricebran and wheat bran, respectively. The hydrogen production potentials of bean curd manufacturing waste, rice bran and wheat bran were 14–21, 31–61 and 10–43 ml.g VS⁻¹, respectively. The hydrogen yields from carbohydrate degradation were 2.54, 1.29 and 1.73 mol of H₂ mol⁻¹ of hexose for bean curd manufacturing waste, rice bran and wheat bran, respectively. The carbohydrate was rapidly consumed just after inoculation. On the other hand, soluble protein was hardly degraded for each substrate, indicating that carbohydrate was the main source of the hydrogen production.