Desalination Brine Discharge

Desalination brine discharge is the concentrated reject stream from seawater desalination plants, typically reverse-osmosis facilities, returned to the sea at roughly twice the intake salinity plus residual antiscalants, coagulants, and chlorination by-products. The dense hypersaline plume sinks and spreads along the seabed, raising salinity and temperature and depressing dissolved oxygen in poorly flushed coastal settings. Seagrass meadows and benthic invertebrates are sensitive: Posidonia oceanica shows mortality at sustained salinity increases of a few practical salinity units above ambient. Mitigation uses multiport diffusers, brine dilution, and siting in high-energy waters. Permitting sets near-field salinity limits at the edge of a mixing zone.