Abstract
The heat pretreatment conditions of food refuse such as leftover food collected from restaurants were examined to improve the gas production efficiency in the mesophilic methane fermentation. In the bench-scale continuous experiment of the mesophilic methane fermentation at the VS loading rate of 2.5kg-VS/m3/day and the HRT of 29 days, the VS removal was improved and the gas production per influent VS increased by 19% with the heat pretreatment. The methane content of produced gas was 68% and there was no difference from that obtained from the control test using non-heat-treated waste.The methane yield per removed VS and the efficiency of carbon conversion to methane were also improved significantly with the heat pretreatment. The measured gas production yield and methane content with the heat pretreatment were notably greater than the theoretically calculated value estimated by the approximate molecular formula and the stoichiometric equation reported to agree well with the experimental results in thermophilic methane fermentation on organic matters in municipal solid waste. The trial calculation results of the energy balance showed that the amount of power generation and available thermal energy can be increased even after compensating the heat required for the pretreatment of waste.
