Hydrogen and methane potential based on the nature of food waste materials in a two-stage thermophilic fermentation process

摘要

The purpose of this study is to investigate the biological H_2 and CH_4 potential based on the nature of organic waste materials in a two-stage thermophilic fermentation process. Three varieties of actual waste specifically potato, kitchen garbage and bean curd manufacturing waste (okara) were selected. The production rates for H_2 and CH_4 were as follows: potato, 2.1 and 1.2 1/1/d; garbage, 1.7 and 1.5 Wd; okara, 0.4 and 1.4 Wd in the continuous processes. The H_2 and CH_4 yields were 20-85 ml H_2/g VS_(added) and 329-364 ml CH_4/g VS_(acdded). respectively. The H_2 yield increased and the CH4 yield decreased in the order of potato, kitchen garbage and okara. The H_2 yield was shown to be not only dependent on the proportion of carbohydrate but also on the hydrolysis pH of the organic waste, which was influenced by the nature of the organic waste materials. Higher yields of H_2 or CH_4 were obtained when the hydrolysis pH of the organic waste was close to the optimum pH range of H_2-producing bacteria or methanogenic archaea in the two-stage fermentation processes.