Abstract: In order to realize the resource utilization of kitchen waste, two-stage fermentation of hydrolysis acidification-anaerobic digestion was adopted. After the kitchen waste was hydrolyzed and acidified for 5 days, the acidified solution was digested by activated sludge for 16 days to test the production efficiency of biomethane using kitchen waste as raw material. The results showed that after hydrolytic acidification, the acid production was obvious, the pH decreased to 4.69, the concentration of acetic acid reached 3.11 mg/mL, and the sCOD of digestive juice increased obviously to 174.34 g/L. The gas production effect in the anaerobic digestion section was obvious, the gas production reached the highest peak within 2 days, and the pH dropped from 7.89 to 7.54, but no significant inhibition was produced. The second peak of gas production appeared on the 6th day, and gradually decreased with the decrease of organic matter content in the system. During the gas production period, the digestion system had always maintained an alkaline state. The average methane yield during the gas production period was 315.47 mL/g VS, the average methane content in cumulative biogas was 53.79%, and the highest content of methane was 67.49%. It can be seen that that two-stage anaerobic digestion can effectively treat kitchen waste.

Key words: kitchen waste, activated sludge, hydrolytic acidification, anaerobic digestion, methane yield