Performance of Nanofiltration for Improving the Drinking Water Quality in a Water Supply Plant with Micropolluted Water Resource

Abstract

Four nanofiltration membranes connected in series were used for improving the drinking water quality in a water supply plant in south China with micropolluted water resource. The performance of the nanofiltration for improving the drinking water quality was investigated. The results showed that nanofiltration was efficient for removal of both traditional water pollution indicators and organic toxicants. More than 95% of TOC and UV254 were removed from the effluent of the traditional water purification process in the water supply plant. The NF effluent had a TOC of no higher than 0.3 mg·L-1 and a UV254 of below 0.005 cm-1. The removal rates of haloacetic formation potential,trihalomathanes formation potential, polycyclic aromatic hydrocarbon(PAHs)and organochlorinated pesticides(OCPs)were 62%, 85%, 50% and 95%, respectively. Genotoxicity of the NF effluent was undetectable in the umu-SOS test. Moreover, no significant difference was observed in the organic pollutants removal of haloacetic formation potential,trihalomathanes formation potential and OCPs among the four NF membranes but in the removal of PAHs with relatively smaller molecular weight. Nanofiltration showed higher removal rate of high-molecular-weight organic matters over low-molecular-weight organic matters. By comparison, only 17% of PAHs, 62% of OCPs and 80% of genotoxicity were removed by advanced treatment of ozone (O3) followed by treatment with biological activated carbon (BAC) in this water plant, indicating that nanofiltration was better for removal of organic pollutants.