Background
Disinfection is a vital step to produce safe drinking water eliminating the incidence of infectious diseases associated with water-borne pathogens. Traditionally, chlorine is the most commonly used disinfectant to treat drinking water. However, the use of chlorine gas or hypochlorite solution is associated with operational concerns especially from remote areas. Continuous electrochlorination (CEC) has gained a lot of attention as an alternative to the traditional use of conventional chlorination technologies. CEC is a highly efficient and reliable mechanism to generate chlorine, however, its effects on surviving bacterial populations have not been yet sufficiently investigated.
Objective
Assess the efficacy of a CEC pilot unit including two successive electrolysis cells (i.e., pre and post oxidation) developed by Water Corporation of Western Australia on the disinfection of waters with different physicochemical characteristics.
Methods
The effects of the oxidants generated by the CEC on the disinfection of water has been tested on five source waters (ground waters and surface waters) located in Perth metropolitan area and regional areas of Western Australia.
Culture of common water-borne pathogens Escherichia coli, Bacillus subtilis and Bacteriophage T4 were pumped into the feed line of the CEC pilot unit operated at flux ranging from 3 m3/h to 30 m3/h; Samples were collected immediately at the outlet of the pilot unit and quenched with sodium thiosulfate to remove any residual chlorine. The number of viable cells and chlorine residual were analysed by the spread plate method and DPD (N,N-diethyl-p-phenylenediamine) colorimetric method respectively, after both pre and post treatment.
Results
The CEC was successfully able to generate about 1.0 mg/L of free residual chlorine at the outlet whatever the initial chloride concentration of the source water. The oxidants generated were able to inactivate 6 log of each microorganism.
Conclusions
The CEC is an efficient and reliable on site generator of chlorine. The oxidants generated by the CEC can remove 6 log of E. coli, B. subtilis and bacteriophage T4.