Chlorine dioxide (ClO2) disinfection, oxidation and disinfection by-products (DBPs)–A short review

Chlorine dioxide (ClO 2 ) is used for disinfection and in some cases pollutant degradation. ClO 2 forms less halogenated by-products than free available chlorine (FAC) but forms chlorite and chlorate as undesired by-products and to some extent FAC. FAC formation may enhance the ClO 2 -based treatment but also form undesired disinfection by-products (DBPs). Halogenated compounds are also formed by intrinsic FAC including brominated and iodinated DBPs. Pre-ozonation, sequential chlorination and biofiltration are common strategies that minimize DBP formation. Further investigation into the formation of intrinsic FAC, especially regarding disinfection mechanisms and DBP formation is required.