Gypsum scale prevention in agricultural drainage water reclamation by nanofiltration membranes

摘要

Semi-arid California San Joaquin Valley, one of the world's largest agricultural regions, requires large amounts of imported irrigation watr. Acute water shortages in California led to serous consideration of systems for the reclamation and reuse of agricultural drainage water. Becuase of their excellent product water flux and reasonable salt rejection at low pressures, nanofiltration (NF) membranes would make reclamation economically viable. However, the drainage water contains high levels of calcuium and sulfate ions, so that gypsum (CaSO4.2H2O) would inevitably scale the membranes.