Pilot-scale gasification of municipal solid wastes by high-rate and two-phase anaerobic digestion (TPAD)

Bioconversion of municipal solid waste-sludge blend by conventional high-ra te and two-phase anaerobic digestion was studied. RDF (refused-derived fuel )-quality feed produced in a Madison, Wisconsin, USA, MRF (materials-recove ry facility) was used. High-rate digestion experiments were conducted with bench-scale digesters under target operating conditions developed from an e conomic feasibility study. The effects of digestion temperature, RDF conten t of digester feed, HRT, loading rate, RDF particle size, and RDF pretreatm ent with cellulase or dilute solutions of NaOH or lime on digester performa nce were studied. A pilot-scale two-phase digestion plant was operated with 80:20 (weight ratio) RDF-sludge blends to show that this process exhibited a higher methane yield, and produced a higher methane-content digester gas than those obtained by single-stage, high-rate anaerobic digestion.