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Abstract

In drinking water, the inactivation efficiency for Escherichia coli, which is an indicator microorganism of pathogenic bacteria, has been evaluated by using an electrolyzer with silver electrodes. Chlorination used for serveral decades, has significant disadvantages that the formation of halogenated disinfection by-products (DBPs) such as THMs and HAAs, and low inactivation efficiency for chlorine-resist microorganisms. On the other hand, disinfection method using electrolysis with silver electrodes is attractive due to a higher sterilization without formation of products. In this study, a sterilization experiment in an electrolyzer with electrodes was carried out to investigate the optimal conditions for electrolysis system. As the results of the experiment, E.coli was not detected at the conditions of contact time (1 and 2 hour) and silver concentration (0.05, 0.07 and 0.1mg/L). Silver ions dissolved from silver anode act as a disinfectant because they are positively changed. When they contact a negatively changed microorganism they electrostatically bond to the organism's cell wall and distort it, thereby affecting the cells ability to absorb nutrients. Eventually the cell wall is breached, amino acids are attracted and cell death results. During the oxidation process silver ions do not get consumed, unlike chlorine that gets destroyed and vaporized. Concentration of silver-ions as low as 0.02mg/L of wat will prevent microbial growth. Furthermore, it can be found that disinfection was occurred by mean of OH radicals formed in electrolysis and potential drop across the electrodes.