Wastewater treatment and resource recovery by loose nanofiltration membrane: A critical review

Although conventional polyamide thin film composite nanofiltration (NF) membrane has demonstrated its high performance in water treatment, its low permeability and selectivity toward salt and pollutants restricted the resource recovery from wastewater. Recently, loose nanofiltration (LNF) with higher pore size (500-2000 Da) attracted increasing attention to address above challenges. This review provides a comprehensive assessment of the recent advances of LNF membrane fabrication methods (e.g., interfacial polymerization and phase inversion) and their application on wastewater treatment (e.g., industrial and municipal wastewater) and resource recovery. The effect of membrane structure, water matrices and operating conditions on LNF membrane performance was illustrated. Moreover, the separation and anti-fouling mechanism of LNF membrane was unveiled. Ultimately, we summarized the advantages, challenges, outlooks and future trends of LNF technology in this field. The rich fabrication methods provide powerful tool to precisely modulate membrane structure for tailored performance, which enables the efficient recovery of resources (e.g., dye, pharmaceuticals and salts) from wastewater. Nanomaterials modify the membrane structure and physiochemical properties of LNF membrane, which influences the separation and anti-fouling performance. This review is intended to consolidate the literature related to LNF technology and guide the development of LNF membrane in advanced water treatment and resource recovery.