Design criteria and operational guidelines for a pilotscale anaerobic digester

Abstract Design considerations for constructing a pilot anaerobic digester are presented. A 4.34 m3 pilot digester was constructed using these criteria. Operational guidelines are presented. Also included is an iterative technique for sizing an internal heat exchanger, suggestions for selecting pumps, meters, and other equipment, and an electrical control system that permits automation of the entire system. The pilot digester operated successfully for more than 4 years with swine manure as a feedstock at a loading rate of 4 kg volatile solids per m3 per day with a 15-day detention time at 35°C. Energy balances indicate that the overall energy efficiency of the digester is a function of ambient temperature surrounding the digester, amount of agitation, and amount of insulation.