ABSTRACT
Nanofiltration (NF) is a pressure-driven membrane with a charged surface and pore size ranging from 0.2 to 2 nm (equivalent to a molecular weight cut-off of 200–1,000 Da). It has been widely used to treat wastewater containing heavy metals. The membrane could retain the multivalent heavy metal ions at the retentate and allow water and some monovalent ions to permeate across. Understanding the nature and properties of the NF under various operating variables before designing a suitable NF system is important. Therefore, this chapter offers a guide to select a suitable NF membrane, covering the types of material, membrane modules and configuration, followed by the influence of operating variables on the membrane performances. The design of the NF system (a standalone NF and integrated NF process) will be discussed. Lastly, the challenges and future development of the NF in treating wastewater containing heavy metals will be highlighted.
