Caption title. At head of title: Project summary. Distributed to depository libraries in microfiche. "Sept. 1984." "EPA/600-S2-84-104."

"A research program on the thermal conditioning of sludge was conducted as part of an overall, long-term sludge management study for the Los Angeles and Orange County metropolitan areas. The major goal of this portion of the study was to investigate the advantages of the thermal conditioning of primary and waste-activated sludges WAS before anaerobic digestion on a continuous-flow and pilot-scale basis. The studies were designed to demonstrate whether thermal conditioning would increase gas production and volatile solids destruction during subsequent anaerobic stabilization of the sludge. Anaerobic digestion and anaerobic filtration were used for sludge stabilization. The effects of thermal conditioning on sludge dewaterability were studied by means of dewatering with a filter press, vacuum filter, scroll and basket centrifuges, and belt filter press. Other items studied were the fate of pathogens and heavy metals and the production and control of odors during the thermal conditioning process. The pilot-scale thermal conditioning unit was tested under a variety of operating conditions. Temperatures and pressures were varied, and thermal conditioning was investigated with and without the use of oxygen. Two types of wastewater sludges were used - WAS and a blend of 65 percent raw primary and 35 percent WAS. An energy analysis was conducted to determine the net energy demands of including thermal conditioning in the sludge process."