Making waves: Harnessing the disinfection byproduct chlorite as an oxidant precursor for micropollutant abatement

Chlorite (ClO₂⁻), a regulated disinfection byproduct from chlorine dioxide (ClO₂) application, is conventionally managed as a pollutant requiring reductive removal. This article highlights a conceptual reframing of chlorite at environmentally relevant concentrations as a versatile precursor for in-situ oxidant generation, offering a "waste-to-resource" strategy that enables the synergistic elimination of chlorite alongside co-occurring micropollutants. We systematically evaluate the efficacy of major activation pathways (photolytic and metal-based catalytic) in transforming ClO₂⁻ into reactive oxidants. Our analysis differentiates their underlying mechanisms and contrasts the resultant reactive species profiles, offering mechanistic insights to guide future pathway selection. We also discuss the formation and control of inorganic and organic byproducts, emphasizing the understudied yet pivotal role of natural organic matter (NOM) as a dominant precursor. Key challenges include deepening mechanistic understanding under realistic conditions, controlling undesired byproducts, and validating process efficacy in complex matrices. Future opportunities lie in exploiting the ClO₂⁻/ClO₂ cycle for integrated oxidation and disinfection, developing robust catalysts, and conducting context‑specific techno‑economic assessments. Ultimately, ClO₂⁻ activation processes represent a promising pathway toward sustainable water purification by converting a problematic byproduct into a treatment asset.