The effect of substrate ratio and total solids on biogas production from anaerobic co-digestion of municipal solid waste and sewage sludge

Recycling waste and converting municipal solid waste (MSW) to useful materials, especially energy sources, is one of the most useful environmental effort, which prevent biological pollution and minimizes the stress on natural resources. This study investigates the improvement of biogas gained from MSW. Anaerobic digestion (AD) MSW and sewage sludge (SS) were studied at different mixing ratios at mesophilic condition. Higher methane yield but longer hydraulic retention time (HRT) was observed by increasing the percentage of MSW. The optimal mixing ratio for biogas production was determined. After 20 days, approximately 90% (376.84 mL/g VS) of the cumulative methane was produced. The same ratio was used for further study on the effect of total solids (TS) (5-25%) on biogas yield. It was found that lower TS levels (5-10%) yield more methane. Biogas production at 5% TS was 64% higher than that of 25% TS. The amounts of methane produced at 5, 10, 15, 20, and 25% TS were 230.3, 196.8, 159.5, 129.4, and 83.3 mL/g VS, respectively.