Effect of Activated Carbon Replacement Ratio in Drinking Water Treatment Plant Activated Carbon Filters on the Removal of Disinfection By-Product Precursors and Pesticide-Related Emerging Contaminants

• • Replacing 70% of activated carbon achieves >85% of the removal efficiency of full replacement for most DOM fractions (except LMWC) and >95% removal for most pesticide-related contaminants, while saving ~30% of new carbon cost. • • UV254 removal reaches 70% at 70% replacement ratio, indicating effective removal of aromatic organic matter, a key DBP precursor. • • Removal of THMs and HAAs is insensitive to replacement ratio, whereas HALs removal improves significantly with increasing ratio, highlighting the importance of adsorbate polarity and molecular structure. • • Triazole pesticides exhibit only ~60% removal even at 70% replacement due to high water solubility and low octanol-water partition coefficient, necessitating alternative treatment or higher replacement ratios.