Enhancing Methane Yield in Dry Anaerobic Digestion from Municipal Solid Waste Through the Intermittent and Low-Strength Ultrasonic Technology

One of the most challenging issues for dry anaerobic digestion (AD) is its limited mass transfer due to low water content; however, the mass transfer can be enhanced by the ultrasonic waves. In this research, a set of ultrasonic technology experiments are evaluated before or during dry AD to enhance methane yield. In the pretreatment stage, ultrasonic could promote the hydrolysis of organic substances. The sCOD concentration was increased by 4 %, and the cumulative methane production was 196.5 mL/g.VS, which was increased by 32 %. Moreover, during the dry AD reaction process, through the intermittent and low-strength ultrasonic technology, the optimal cumulative methane production was 230.65 mL/g.VS, which was increased by 56%; the maximum daily methane production rate was 38.46 mL/g.VS, which was increased by 77.17 %. The lag period of dry AD was shortened, and the gas production peak was advanced. The dominant microbial communities in dry AD system are analyzed. This research will provide suggestions for the application of dry AD technology to MSW treatment.