City of Spokane Riverside Park Water Reclamation Facility – Tertiary Membrane Facility

The City of Spokane is implementing an innovative use of tertiary membrances to help address its integrated water quality planning to meet the total maximum daily load (TMDL) requirements on the Spokane River. At the City’s Riverside Park Water Reclamation Facility (RPWRF) the tertiary membrane filtration system is designed to meet an average daily flow of 50 mgd with a peak flow up to 75 mgd, achieving an effluent total phosphorus criteria of 0.018 mg/L. This effluent criteria of 0.018 mg/L from the membrane facility allows for diversions of secondary effluent flows greater than 75 mgd, and infrequent wet-weather diversions around secondary treatment with flows above 125 mgd while still meeting the TMDL requirements during the critical season. A pilot study was used to validate the ability of membrane filtration system from two prequalified vendors to achieve the required effluent qualtiy.