Comparison of the formation of aldehydes and carboxylic acids in ozonated and electrochemically treated surface water

Abstract

This study compared effects of conventional ozonation and electrochemical oxidation (EO) on the formation of aldehydes and aliphatic carboxylic acids produced via the oxidation of natural organic matter (NOM) present in a low-mineralized surface water with a relatively low NOM concentration. Conventional ozonation and EO were effective in degrading the aromatic moiety of NOM characterized by the absorbance at 254 nm. Yields of aliphatic carboxylic acids in the ozone treated water were dominated by formate, acetate and oxalate, while no acetate was observed in the case of EO treatment. The speciation of aldehydes was similar in the case of ozonation and EO treatment, but the aldehydes yields were notably higher for ozonation. The presence of the elevated carbonate concentration moderated the changes in disinfection by-products (DBPs) concentration in the EO treated water due to the interception of ∙OH by HCO₃^-, while it did not affect ozonation treatment. This study allows gaining more insights into the nature of processes characteristic and optimization of disinfections based on ozonation and EO methods.

Keywords: Aldehydes; Aliphatic carboxylic acids; Disinfection by-products; Electrochemical oxidation; Ozonation.