Removal of chlorine dioxide disinfection by-products by ferrous salts

Chlorine dioxide when used as an effective disinfectant forms undesirable d isinfection byproducts, i.e. chlorite and chlorate ions. The aim of this re search was to study the removal of these ions by ferrous ions in the presen ce or absence of oxygen. The efficiency of Fe2+ for ClO2- and ClO3- removal was followed by a determination of their initial and final concentrations, pH and Delta Fe+2 consumed/Delta ClO2- removed ratios. The optimal weight ratio of Delta Fe+2 consumed/Delta ClO2- removed for complete ClO2 removal was found to be close to the theoretical calculated value of 3.31. It was p roved that ferrous salts can reduce chlorite ions to harmless Cl- ions. Thi s method can be recommended as a part of ClO2 disinfection to ensure safe d rinking water, with no harm to water consumers and to the environment. (C) 2000 Elsevier Science Ltd. All rights reserved.