Reduction of Bromate and Natural Organic Matters (NOM) During the Transition from Fresh Granular Activated Carbon (GAC) to Biological Activated Carbon (BAC)

Two different granular activated carbon (GAC) filters were utilized to investigate the removal efficiency of bromate and natural organic matters (NOM) during the transition from fresh GAC to the biological activated carbon (BAC). The removal efficiency of bromate, nitrate, UV254, DOC, and trihalomethane formation potential (THMFP) in GAC filter apparently decreased during the transition from fresh GAC to BAC. The high level of anions and NOM, and high pH value may slow down the bromate reduction in GAC filter, in initial period GAC filter still has a significant reduction of bromate, with a calculated average reduction rate of 71.9%. Moreover, the GAC filter demonstrated a sustainable and effective bromate reduction in long-term operation. Therefore, if suitable GAC was used, the filter can achieve a plausible bromate reduction efficiency with a long bedlife. Backwashing treatment has only a limited improvement on bromate reduction during transition from fresh GAC to BAC.