Raw sewage enters the treatment facility through the sanitary sewer system. Large objects and grit which may damage pumps or other equipment are screened out. The solids collected in the preliminary treatment process are dewatered and hauled away to a landfill. In the primary treatment process, primary sedimentation tanks use gravity to settle large solids from the waste stream. The removed solids are pumped to anaerobic sludge digesters for further processing, while the wastewater continues to the biological treatment.
Aeration basins are the heart of the biological treatment process.
Oxygen, is supplied by aeration, which ensures a proper environment for microorganisms. The microorganisms group together and settle to the bottom of the secondary sedimentation tanks. Some of these solids are then returned to the aeration basin as seed organisms to help break down the fresh incoming sewage. Organisms from the secondary sedimentation tanks may also be pumped to anaerobic sludge digesters, or to the phosphorus removal tanks. In the phosphorus removal tanks, organisms loaded with phosphorus collected from the wastewater are deprived of oxygen for a long time.