ANAEROBIC-DIGESTION OF MUNICIPAL SOLID-WASTE IN A NONMIXED SOLIDS CONCENTRATING DIGESTER

This paper reports on the performance and characteristics of a 4.5 m3 nonmixed, vertical flow Experimental anaerobic digestion Test Unit (ETU) treating refuse-derived fuel (RDF) and primary sludge. It was operated at 35°C and a loading rate of 3.2 kg VS/m3/d. Three tests involving chemical nutrients addition or effluent supernatant recycle were completed. Hydraulic retention times were 16, 18, and 19 d, respectively. Methane yields ranged from 0.24 to 0.28 m3/kg VS fed, which were 10-20% higher than that from a continuously-stirred tank reactor. Methane compositions were around 58%. Solids distribution, pH and volatile fatty acids (VFA) concentrations profiles, and the ability of microbial communities at various depths to utilize acetate and other VFAs were used to characterize the ETU. © 1990 Humana Press Inc.