Impacts of advanced oxidation processes on disinfection byproducts from dissolved organic matter upon post-chlor(am)ination: A critical review

This review provides a critical evaluation of the literature to fully delineate the impact of advanced oxidation processes (AOPs) on the generation of disinfection byproducts (DBPs) from dissolved organic matter (DOM) upon post-chlor(am)ination. The study established that the overall impact of AOPs on DBP generation from raw water and wastewater is determined by the original chemical properties of the DOM and the extent of the radical dose. A given DOM sample that was originally resistant to halogenation would experience increase in DBP formation after an AOP while those that rapidly react with chlor(am)ine and are readily halogenated, are likely to produce lower concentrations of DBPs after an AOP. However, a high radical dose with extensive mineralization would reduce the DBP formation potential (DBPfP) irrespective of the DOM properties although it may lead to the generation of significant amounts of inorganic oxidation byproducts. All the common oxidative radicals appear to exert nearly the same effects on DBPfP. The higher selectivity of SO4 center dot- compared to HO center dot and Cl-center dot may achieve enhanced degradation of the DOM hydrophobic fractions and increased overall mineralization of the whole DOM, both effects which may directly lead to reduced DBPfP. However, these advantages may only be temporary or of limited impact in practical conditions due to the ubiquity of halide ions or under high radical doses. Novel conceptual parameterizations were proposed to facilitate the analysis of the impact on DBPfP of AOPs. Furthermore, some inconsistencies in the literature were identified and discussed, and further research themes were highlighted.