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.
Yin et al. (Wed,) studied this question.