San Diego City Council members approved a Water Purification Demonstration project using a indirect potable reuse (IPR) program.
Implementation of an IPR would provide a significant new local water supply, while reducing the amount of primary effluent discharged to the ocean, helping the City avoid a $1.5 billion upgrade of the Point Loma Wastewater Treatment Plant.
IPR projects take tertiary treated municipal wastewater through an extensive filtration process using membranes followed by some form of advanced oxidation. Advanced oxidation methods used include ozone/peroxide and UV/peroxide. These methods can remove micro pollutants and kill any remaining micro organisms. The water is then normally injected into a well field for later recovery for drinking water use. A direct potable reuse project (DPR) would take the water directly to a drinking water treatment plant.
A two-year study of a 1 MGD (3,785 m3/d) demonstration project at the North City Water Reclamation Facility (WRF) demonstrated the robustness of the multi-barrier MF/RO and advanced oxidation arrangement to produce better-than-potable-quality water from tertiary effluent. The California Department of Public Health (CDPH) gave conditional approval to the proposed IPR concept.