Biopolymers present in tap water improve disinfection byproduct removal by nanofiltration

Nanofiltration (NF) is an effective and well-established technology in the purification of drinking water. However, the efficiency of NF membranes in rejecting organic contaminants, and their susceptibility to fouling, are significant concerns that can impede the application of the treatment process. The heterogeneity of drinking water sources presents complex pollutants, challenging the application of the NF process. To address this, research studies typically focus on modifications to the NF membrane to enhance its performance against a diverse range of contaminants. However, there has been insufficient consideration given to the possible correlations between specific substances in source waters and the NF membrane. In this study, we compared the performance of two NF systems using tap water samples from two distinct districts in Beijing, characterized by their disparate biopolymer compositions. Specifically, Haidian's tap water, partly sourced from the Miyun Reservoir, contains unique biopolymers absent in Fangshan's tap water. These biopolymers formed a protective layer on the NF90 membrane surface, enhancing the removal of natural organic matter (NOM) and disinfection byproducts (DBPs), thereby improving the treated water quality. Meanwhile, this biopolymer layer mitigated irreversible fouling and ensured the sustained efficiency of the NF90 membrane, highlighting its potential for long-term, effective operation in water purification processes. These findings provide a deeper understanding of the interplay between source water characteristics and NF membrane properties, offering insights into the optimization of NF processes for diverse water applications.