Effects of reductive inorganics and NOM on the formation of chlorite in the chlorine dioxide disinfection of drinking water.J Environ Sci (China). 2021 Jun; 104:225-232.JE
Chlorine dioxide (ClO2) disinfection usually does not produce halogenated disinfection by-products, but the formation of the inorganic by-product chlorite (ClO2-) is a serious consideration. In this study, the ClO2- formation rule in the ClO2 disinfection of drinking water was investigated in the presence of three representative reductive inorganics and four natural organic matters (NOMs), respectively. Fe2+ and S2- mainly reduced ClO2 to ClO2- at low concentrations. When ClO2 was consumed, the ClO2- would be further reduced by Fe2+ and S2-, leading to the decrease of ClO2-. The reaction efficiency of Mn2+ with ClO2 was lower than that of Fe2+ and S2-. It might be the case that MnO2 generated by the reaction between Mn2+ and ClO2 had adsorption and catalytic oxidation on Mn2+. However, Mn2+ would not reduce ClO2-. Among the four NOMs, humic acid and fulvic acid reacted with ClO2 actively, followed by bovine serum albumin, while sodium alginate had almost no reaction with ClO2. The maximum ClO2- yields of reductive inorganics (70%) was higher than that of NOM (around 60%). The lower the concentration of reductive substances, the more ClO2- could be produced by per unit concentration of reductive substances. The results of the actual water samples showed that both reductive inorganics and NOM played an important role in the formation of ClO2- in disinfection.