Chlorine-Free Electrochemical Disinfection of Water Contaminated With Escherichia Coli

Deionized water highly contaminated with E.coli and containing sodium sulfate as an electrolyte was treated in a circulating system with the use of an electrochemical cell with copper electrodes and pulsed electrical signals at 2 V voltages, 50 Hz frequency and 0.1-0.2 A current. The process was found to be effective and the percentage of the initial concentration of bacteria which were destroyed was found to be proportional to both treatment time and concentration of hydroxyl radicals. Detection of hydroxyl radicals formed during electrolysis was confirmed using N,N-dimethyl-p-nitrosoaniline (RNO)  as a spin trap, and concentration of copper cations in solution was estimated by atomic absorption. The maximum of the disinfection efficiency, i.e. a minimum of time needed for complete disinfection was obtained in the experimental setup where  4 copper electrodes with parallel connection have been used. Several parameters, such as changes in different electrode materials and contact wire materials were analyzed, and recommendations how to increase the disinfection efficiency and decrease the time of treatment were discussed.