Comparison between chlorination and ozonation treatments for the elimination of the emerging contaminants amitriptyline hydrochloride, methyl salicylate and 2-phenoxyethanol in surface waters and secondary effluents

BACKGROUNDA new class of micropollutants, generally called emerging contaminants (ECs), is increasingly found in surface waters and wastewaters. Owing to their potential ecologic and health risks, ECs must be removed using different procedures, such as chemical oxidation processes. RESULTSThe oxidation of the selected ECs amitriptyline hydrochloride, methyl salicylate and 2-phenoxyethanol has been investigated by means of two known oxidizing agents: chlorine and ozone. The efficiencies of elimination of each system have been compared, and apparent second-order rate constants of the reactions involved are determined. The variation of these kinetic parameters with pH is also evaluated, which enables determination of the intrinsic rate constant values for the oxidation reactions of the neutral and dissociated species. In addition, the simultaneous oxidation of these selected ECs in different water systems (ultrapure water, surface water from a reservoir and two secondary effluents) is studied, and the influence of operating conditions on the removal efficiency is established. CONCLUSIONThe reaction rates between chlorine or ozone and neutral and dissociated species revealed that the ozonation process is around three orders of magnitude higher than chlorination. (c) 2014 Society of Chemical Industry