Direct nanofiltration for drinking water and wastewater treatment

Water treatment using a nanofiltration (NF) membrane is an effective advanced water treatment process for achieving high organics removal. This presentation will cover our recent studies examining the feasibility of direct (i.e., no pre-treatment) NF treatment of surface water and wastewater using a submerged flat-sheet NF membrane module. When a direct NF system was employed for surface water treatment, we observed only slight membrane fouling over three months. The separation performance of the NF system remained high: total organic carbon (TOC) removal remained at 80-90% in most sampling occasions. Membrane surface characterization revealed that many substances covered the membrane surface. It was speculated that these substances deposited on the membrane surface provide a small contribution to the hydraulic resistance. Further, the membrane foulant was readily removed by physical cleaning, and the permeability fully recovered. This indicates that the membrane foulant did not penetrate the pores of the NF membrane. The results attained through the on-site test suggest the viability of direct NF treatment of surface water for achieving high water quality and stable system operation. In addition to the drinking water treatment, the presentation will provide the results of applying the direct NF system for wastewater treatment.