Enhancement of hydrogen production by recycling of methanogenic effluent in two-phase fermentation of food waste

摘要

The feasibility of operational strategies was investigated for hydrogen and methane production from food waste. Food waste was heat-treated at 70 ℃ and fed to a two-phase anaerobic sequencing batch fermenting system. Maximum hydrogen productivity of 1.19 m~3 H_2/m~3 d was observed at a food waste concentration of 30 g carbohydrate/L, a hydraulic retention time of 2 d, and a solids retention time of 3.4 d. The effluent from hydrogenesis was efficiently converted to methane at an organic loading rate of up to 3.6 kg COD/m~3.d. The methanogenic effluent was then recycled to the hydrogenesis reactor without any pretreatment. The recycled effluent not only successfully replaced external dilution water and decreased alkaline dosage by 75%, but also increased hydrogen production by 48%, resulting in hydrogen productivity of 1.76 m~3/m~3 d. The two-phase digestion with recycling would convert 91% of organic pollutants in food waste to hydrogen (8%) and methane (83%) without any external dilution water.