FULL-SCALE MESOPHILIC ANAEROBIC CO-DIGESTION OF MUNICIPAL SOLID-WASTEAND SEWAGE-SLUDGE - METHANE PRODUCTION CHARACTERISTICS

The methane production characteristics of a full scale anaerobic bioga s digester processing the putrescible fraction of municipal solid wast e (PFMSW) and sewage sludge (SS) were studied by using the operation d ata of the digester and laboratory experiments. The batch assays indic ated methane yields of 3001 kg volatile solids (VS)(-1) for PFMSW and 2201 kg VS-1 for SS. The full scale digester showed methane production yields up to 90% of the methane yield potential of the added feed. Th e rates of methane production and the specific methanogenic activities varied during the cycle of feeding. Apparently, the methanization in the digestion process was substrate-limited, especially during weekend s when no feed was added. The batch studies indicated that the propion ate and butyrate conversions were no more limiting than acetate methan ization. The sludge from the digester was more active than the sludges from digesters processing sewage sludge alone. (C) 1996 ISWA.