Micropollutant removal via nanofiltration: The effect of salt concentration — Theory and experimental validation

Nanofiltration guarantees high water recovery and low energy consumption in removing micropollutants (MPs). In this study, we derive a concise model to describe MP removal with nanofiltration membranes. We compare the results from the model with experimental data for the removal of 7 MPs with 5 salt concentrations using the NF270 membrane. Our findings indicate that the model accurately describes MP transport through nanofiltration membranes. Furthermore, we evaluate the effect of salt concentration on MP rejection. The results show that salt concentration impacts MP rejection differently based on MP charge and size. Increasing salt concentration decreases the rejection of counter-charged MPs that are small and increases the rejection of counter-charged MP that are large. • Solution friction theory can describe micropollutant rejection by nanofiltration. • Salt concentration affects rejection by electromigration and charge exclusion. • Salt concentration’s effect on rejection depends on micropollutant size and charge.