Effect of residual H2O2 on the removal of advanced oxidation byproducts by two types of granular activated carbon

Abstract Advanced oxidation processes (AOPs) such as UV/hydrogen peroxide (H2O2) systems are typically paired with a polishing granular activated carbon (GAC) filter to remove degradation byproducts from AOP effluent. In this study, the impact of residual H2O2 on the removal of five frequently detected AOP byproducts (formic acid: FA, acetic acid: AA, oxalic acid: OA, formaldehyde, and glyoxal) by two types of GACs (Filtrasorb-600/F-600 and Centaur) was investigated in batch experiments. The presence of byproducts significantly inhibited the decomposition of H2O2 on Centaur, but no inhibition was observed on F-600. In multi-component systems, byproduct removal kinetics and capacity of both GACs decreased due to competition. Centaur showed a sequential removal of byproducts following OA >FA/AA >aldehydes in mixtures. The presence of 10 mg/L H2O2 showed a temporary inhibition (0-72 h) on the removal efficiency of FA and AA by F-600, respectively. However, in multicomponent tests the presence of H2O2 had little impact on the removal efficiency of byproducts. Abiotic control experiments suggested the mechanism of byproduct removal by GACs was likely a combination of adsorption, biodegradation, and catalytical decomposition.