Beyond precursor removal: How anion exchange resin structure shapes disinfection byproduct profiles and reduces toxicity in reclaimed water.

Disinfection byproducts (DBPs) with various toxic effects could pose potential risks to reclaimed water safety. Despite the proven efficacy of anion exchange resins (AERs) in removing DBP precursors, the influence of their structural properties on removing complex precursors remains poorly understood. This study systematically investigated the removal efficiency of four AERs with different structural properties for DBP precursors in reclaimed water, as well as their control effects on DBPs, total organic halogen (TOX), and effluent toxicity after chlorination, while further elucidating the underlying mechanisms. The results showed that AER treatment effectively controlled DBP precursors, DBPs, and TOX, with resin performance ranking as polyacrylic based strongly basic magnetic resin > polystyrene based strongly basic gel-type resin ≈ polystyrene based strongly basic macroporous resin > polyacrylic based strongly basic macroporous resin. Notably, amine/amide release enhanced chloroacetamide formation, whereas precursors did not contribute to nitrosamines. In terms of toxicity control, AER treatment significantly reduced the cytotoxicity of Chinese hamster ovary (CHO) cells, with control efficiencies of 19.0-71.5%. Moreover, CHO cell cytotoxicity showed a strong linear correlation with TOX, indicating that TOX can serve as a reliable indicator for predicting cytotoxicity in chlorinated wastewater. Mechanistic analysis revealed that resin properties played distinct roles in the treatment process. Higher moisture content primarily hindered the control of DBPs, while greater exchange capacity was less effective at removing precursors. Conversely, increasing average pore size and micropore volume enhanced control efficiency, particularly for brominated DBPs.