Desalting residuals: A problem or a beneficial resource?

• Published in: Desalination Vol. 102; no. 1; pp. 107 - 117
• Main Authors: Everest, William R., Murphree, Troy
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 1995; Elsevier
• Subjects: Applied sciences; Desalination; Drinking water and swimming-pool water. Desalination; Ecosystems; Environmental impact; Environmental protection; Exact sciences and technology; Ocean dumping; Pollution; Q1; Runoff; Water treatment and pollution; California; United States; North America; America; USA, California, San Diego; Drinking water treatment; Industrial waste water; Water supply; Desalination; Brine; Reverse osmosis; Cost analysis; Waste water discharge; Ground water
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/0011-9164(95)00047-6

The Sweetwater Authority, which serves 160,000 people in southern San Diego County, has adopted a long-range goal to be less dependent on imported supplies, especially in water-short years. The Authority is actively developing a program of brackish groundwater and urban runoff demineralization. Various options have been evaluated for disposal or reuse of the concentrate from the proposed desalination plant. These include: 1) discharge to San Diego Bay, 2) reuse in coastal wetlands, 3) discharge to existing or proposed sewer networks, and 4) discharge through deep well injection. Discharge to San Diego Bay may have regulatory constraints which would be imposed by the San Diego Regional Water Quality Control Board (RWQCB). A unique opportunity exists to utilize concentrate for beneficial uses for wetland habitat development such as brackish water wetlands within the Sweetwater Marsh National Wildlife Refuge (NWR). The NWR has expressed an interest in utilizing the concentrate as a continuous water supply. Concentrate disposal into the City of San Diego sewer system could only occur through conveyance lines which will not convey sewage to proposed reclamation facilities. Injection of concentrate into the San Diego Formation could have a beneficial effect to the quality of the groundwater in the San Diego formation if it occurs close to the coast but may have an adverse impact on inland groundwater. The least expensive alternative is to discharge concentrate into San Diego Bay, however, concentrate recycling would be beneficial to the natural environment. Brackish coastal wetlands can serve as receiving waters for the concentrate. This option is somewhat more costly but can provide possibilities for mitigation of project environmental impacts.