RESUMO
Two opposing views are held about the effects of desalination plants on coastal environments. One view is that brine discharged from desalination plants has minimal impact on the coastal environment. The other opinion claims that discharges from desalination plants pose a potential environmental hazard to coastal environments and particularly to those of the Arabian Gulf. The present study was carried out to determine whether negative environmental impacts could be detected in coastal waters of the Gulf and Red Sea near discharges from desalination plants in Saudi Arabia. Phytoplankton abundance, concentrations of chlorophyll a, nutrients, total suspended solids, trace metals, chlorination by-products, bacterial growth, and toxicity of effluents were assessed. Results indicate the brine discharges were not toxic to fish or brine shrimp. Mitigation of impacts from elevated temperature, salinity and chemicals in dual purpose plants is partly achieved by pre-dilution of brine reject stream with cooling water. Alternative pretreatment methods, chlorination and waste treatment are considered. There is accumulation of corrosion metals in sediments at the discharge site of a plant on the Gulf coast. However, their concentrations were within regulatory limits.
