AWWA JAW46208

Effective use of chlorine dioxide as an alternative disinfectant in water treatment may require removal of the byproduct chlorite ion (ClO2-). This study evaluated the effect of alkaline conditions (pH 7-10) and the presence-absence of dissolved oxygen on the ability of ferrous iron [Fe(II)] to reduce ClO2- ion to chloride ion (Cl-). Fe(II) dosing from 3.5-4.0 mg Fe(II) per mg ClO2- provided for efficient removal of ClO2- over the targeted pH range. Furthermore, no byproduct formation of chlorate ion was observed. Results from mass balance studies indicated that approximately 95 percent of the reacting ClO2- was chemically reduced to Cl-. Includes 12 references, tables, figures.