Enhanced micropollutants removal by nanofiltration and their environmental risks in wastewater reclamation: A...

The emerging contaminants, in particular pharmaceuticals and personal care products and environmental estrogens, have been received global concerns in recent years. Nanofiltration (NF) as an advanced tertiary treatment technology can be a reliable and potential tool for micropollutants removal. However, the influence of operation conditions of NF system to micropollutants rejections in an engineering application, is still lacking. Here, a pilot-scale NF system was set up to investigate its removal efficiencies to 49 micropollutants under different operation conditions by treating actual municipal wastewater. The results showed that the rejections of positively and neutrally charged micropollutants with molecular weight higher than 250 g mol^-1 were both higher than 80%. Besides, most negatively charged micropollutants were also rejected higher than 80% under different operation conditions. The rejections of most micropollutants increased with temperature decreased from 25 °C to 13 °C, which was primarily ascribed to decrease of pore size of NF membrane at low temperature. Compared with the water recovery rate of 80%, lower rejections of micropollutants were observed with lower water recovery rate of 60%. Except for sulfamethoxazole, the risk quotients of other detected 20 micropollutants in NF effluent were all lower than 1.0, showing medium or no risks to aquatic organisms. This study might aid understanding the performance of micropollutants rejections by NF in actual engineering application and could give guideline to the implementation of NF technology in future advanced treatment processes.