Xziox Chlorine dioxide (ClO2) is effective as both a disinfectant and an oxidant in water and wastewater treatment. Its selective reactivity makes chlorine dioxide a powerful oxidizing agent useful in many water treating applications for which chlorine and other oxidizing agents are unsuitable. Chlorine dioxide reacts rapidly with soluble forms of iron and manganese to form precipitates that can be removed through sedimentation and filtration. Preoxidation with chlorine dioxide is effective for iron and manganese removal and improves coagulation and settling, resulting in better filter-run times.