Technical feasibility of anaerobic co-digestion of sewage sludge and municipal solid waste

Experiments were conducted using one-litre anaerobic batch bioreactors operated mesophilically (37 degrees C) and fed a mixture of primary sludge (RAW), thickened waste activated sludge (TWAS) and simulated organic municipal solid waste (MSW). A mixture of 25% MSW and 75% sewage sludge (60% RAW, 40% TWAS) yielded the highest biogas production. Based on biogas production, the most anaerobically biodegradable components were the white paper and grass components of the MSW. The TWAS and the newspaper components of the MSW were found to be the least biodegradable components. Both particle size and total solids concentration of the feed had a significant impact on the performance of the process. Over the operating region studied, the optimal operating conditions in terms of biogas production and volatile solids removal were at small particle sizes (0.85 mm, the smallest studied) and high total solids concentrations (22.1%, the highest studied).