Chemical aspects and by-products of electrolyser

Abstract

The electrolyser is a disinfection device consisting of a series of porous graphite plates through which water flows while low voltage and current are applied. This electrolyser had been demonstrated successfully for efficient microbial (coliform bacteria, bacteriophage, Giardia, and Cryptosporidium) inactivation before this study. In this study, chemical aspects were evaluated in terms of the formation of disinfectants and/or oxidants as well as disinfection by-products (DBPs) during the disinfection by the electrolyser. Experiments were performed under constant electrolyser conditions but variable water quality conditions (electrolyte type and concentration, dissolved organic carbon, bromide ion (Br-) and, to an extent, pH). It was shown that disinfectants and (chlorinated or ozonated) DBPs could be measured successfully for the effluent samples from the electrolyser. Chlorination by-products did not pose any problem in compliance to drinking water regulations, while bromate and chlorate (ozonation by-products) were shown to be formed at levels near their respective regulation levels, but only under extreme water quality conditions.