Application of nanofiltration membranes in membrane bioreactors (MBRs): A Review

Nanofiltration (NF) membranes have come a long way since it was first introduced during the late 80 s. With its properties between those of ultrafiltration (UF) and reverse osmosis (RO), NF membranes have been used in many interesting applications especially in water and wastewater treatment. New applications of NF in wastewater treatment are also explored especially for MBR. The membrane bioreactor (MBR) system is one of the most suitable technologies for wastewater treatment. The review will start by looking at the fundamental of NF membranes which include separation mechanism of NF membrane, followed by other important aspects of MBR which can directly affect the process performance, membrane material selection based NF membranes (Polyamide, Cellulose triacetate and Chitosan) and related membrane properties improvement methods. Various preparation methods of fabricating improved NF membrane characteristics mainly interfacial polymerization, UV grafting/photo-grafting and layer-by-layer modification also were included. Finally, fouling which is the limiting factor of widely used NF membrane in MBR was considered. The review signified the huge potential of NF membranes for future research and development.