Desalination of high salinity brackish water by an NF-RO hybrid system

Desalination of brackish water is an important approach to overcoming freshwater shortage. 85% of brackish water contains 1–10 g/L of salt; however, most work on brackish water desalination targets at low salinity (1–5 g/L) brackish water. This work looks into membrane desalination processes suitable for high salinity brackish water. Feed waters with a high-concentration (≥10 g/L) of NaCl or mixed NaCl/MgSO4 salts were considered, and the desalination performance of representative commercial nanofiltration membranes (VNF2 and ESNA1) and low-pressure reverse osmosis membranes (ULP100, LP100, and ESPA1) were evaluated. It was revealed that the desalination process can be operated at a pressure below 1.6 MPa, and the combination of ULP100-VNF2 arranged in series was a good option for production of freshwater from the high-salinity brackish water.