Anaerobic Digestion Tank
Sludge removed by primary sedimentation is stabilized by anaerobic digestion in anaerobic digestion tanks which are a part of the primary treatment facilities. Waste sludge from the carbonaceous and nitrification activated sludge processes are also stabilized by anaerobic digestion. Methane gas produced by the anaerobic digestion process is burned in five 500 KW methane fueled engine generators to produce electricity. This system produces approximately 20 percent of the plant's electrical requirement.
Sludge Heat Drying Facility
Digested sludge from the anaerobic digestion process is dewatered by belt filter presses or dried on sand drying beds. The belt press sludge is then dried to produce a fertilizer product in a heat drying plant using a natural gas fired rotary kiln. This biosolids product goes to distribution and marketing. Biosolids that are not heat dried are applied to agriculture land as a soil amendment.