Formation of aldehydes upon ClO2 disinfection.

Carbonyl compounds are considered to be the most common ozonation by-products. Apart from well-known chlorites and chlorates, chlorine dioxide (ClO(2)) also generates organic by-products. The goal of this paper is an investigation into the influence of disinfection with ClO(2) on the aldehydes formation. Three types of waters were disinfected with different doses of ClO(2) at the various pH values. The results of size exclusion chromatography show that the reaction of ClO(2) with humic fraction of natural organic matter proceeds mainly on an aromatic part of the molecules. The results obtained indicate that the level of carbonyls concentration can significantly increase with the time of ClO(2) reaction with carbonyl precursors in treated water. There is no noticeable correlation between quantity of aldehydes and pH value of disinfected water. The range of "productivity" of aldehydes in water treated with chlorine dioxide is similar to the range estimated for the carbonyls formed upon ozonation.