Dr. Pfeffer’s major teaching and research areas were in biological wastewater treatment processes, and processing and disposal of solid wastes. His primary research applies biological systems to processing and disposal of solid and liquid waste streams. Laboratory research initiated in 1968 on an anaerobic fermentation process for the conversion of municipal solid waste to a methane gas evolved into an evaluation of a proof-of-concept experiment known as RefCoM. His most recent research involves the movement of heavy metals (lead) through clay liners.