Comparison of advanced oxidation processes for the removal of natural organic matter

This study examined the impact of UV, ozone (O₃), advanced oxidation processes (AOPs) including O₃/UV, H₂O₂/UV H₂O₂/O₃ in the change of molecular weight distribution (MWD) and disinfection by-product formation potential (DBPFP). Bench-scale experiments were conducted with surface river water and changes in the UV absorbance at 254 nm (UV₂₅₄), total organic carbon (TOC), trihalomethane and haloacetic acid formation potential (THMFP, HAAFP) and MWD of the raw and oxidized water were analyzed to evaluate treatment performance. Combination of O₃ and UV with H₂O₂ was found to result in more TOC and UV₂₅₄ reduction than the individual processes. The O₃/UV process was found to be the most effective AOP for NOM reduction, with TOC and UV₂₅₄ reduced by 31 and 88%, respectively. Application of O₃/UV and H₂O₂/UV treatments to the source waters organics with 190-1500 Da molecular weight resulted in the near complete alteration of the molecular weight of NOM from >900 Da to <300 Da H₂O₂/UV was found to be the most effective treatment for the reduction of THM and HAA formation under uniform formation conditions. These results could hold particular significance for drinking water utilities with low alkalinity source waters that are investigating AOPs, as there are limited published studies that have evaluated the treatment efficacy of five different oxidation processes in parallel.