Anaerobic co-digestion of municipal solid waste and sewage sludge.

As a solution to the problems of municipal solid waste management, anaerobic digestion possesses the optimal combination of volume reduction, probability of success and potential for both energy and resource recovery. An innovative application of anaerobic processes is the co-digestion of sewage sludge and the organic fraction of municipal solid waste (OFMSW). The purpose of this study is to evaluate the technical feasibility of this process in the context of typical Canadian solid waste. Lab-scale experiments were initially conducted using one litre batch bioreactors operated mesophilically (37$\sp\circ$C) and fed a mixture of primary sludge (RAW), thickened waste activated sludge (TWAS) and simulated OFMSW. To facilitate organics solubilization, three pretreatments were evaluated: thermal, alkaline and thermochemical. Using a central composite experimental design, two factors were studied, the total solids content of the feed and its particle size. For all three pretreatments, second order empirical models were developed with respect to common indicators of metabolic activity, namely, biogas production, biogas methane concentration, soluble chemical oxygen demand (COD) removal and total and volatile solids reduction. (Abstract shortened by UMI.)