Full-scale testing of a water reclamation system

The Central Contra Costa Sanitary District, California, is designing a 3-mgd (114,000-cu m/day) water reclamation plant to supply cooling and process water to nearby industries. To establish process reliability and provide design data, an advanced treatment test facility was built in 1971. It tested on a 0.5-mgd (1,900-cu m/day) basis lime clarification in primary sedimentation, oxidation-nitrification, and biological denitrification. System performance has been stable, with very low concentrations of organics and suspended solids in the nitrified and denitrified effluents. Total nitrogen in the denitrified effluent averages less than 2 mg/l, and total phosphorus is less than 1 mg/l. Total alkalinity decreases through the process. The process can dependably produce the quality of effluent needed for prospective users.