Development of lower cost seawater desalination processes using nanofiltration technologies — A review

• The available data for the commercial NF membranes were listed for comparison.
• The integrating of NF with various types of desalination technologies was reviewed.
• The perspectives of lower cost seawater desalination were provided in the future.

The implementation of seawater desalination, a key strategy to secure fresh water supply in arid and coastal regions, is greatly thwarted by its high cost relating to high energy and equipment cost associated with pressure and the high system or membrane fouling associated with the bi-valence ions in the sea water. Nanofiltration (NF), a lower pressure membrane process with high rejection for divalent ions, had been identified as a key component to reduce the costs relating to both pressure and fouling in the desalination process. Lower cost seawater desalination processes had been developed by integrating NF with various types of desalination technologies including reverse osmosis (RO), forward osmosis (FO), electrodialysis (ED), multistage flash (MSF), multieffect distillation (MED), membrane distillation (MD) and ion exchange (IX). In this paper, after comparing the performance of currently available NF membranes, we attempt to review the recent progresses made in the development of lower cost seawater desalination processes using NF technologies and provide future perspectives for NF technologies.