Electrochemical Disinfection of Microorganisms Using Palladium Coated Carbon Cloth Electrodes

Abstract

The electrochemical disinfection was carried out using high efficiency electrolytic cell equipped with palladium coated carbon cloth electrodes and low resistance separator where the electrolytic solution passed through parallel to the electrodes. The suspension containing microorganism was flowed through from the symmetric anode compartment to the cathode one, and vise versa. In addition to the efficient disinfection, the secondary pollution due to the electrochemically formed HClO, H+, and OH- was suppressed to minimum. The microorganisms used, Escherichia coli and germinated Bacillus subtilis, were almost perfectly disinfected at very low current, 7 to 10 rnA at a flow rate of 50 cm3 min-1. Even B. subtilis spore was disinfected almost perfectly in the present cell at 200 rnA and 6 V. It was found that the disinfection occurred far effectively in the anode compartment in the chloride containing suspension. According to the direct observation during the disinfection, it was found that the microorganisms were repelled and could not reach the electrode surface in the suspension containing chloride presumably due to the effect of HClO evolved at the anode. The disinfection must occur apart from the electrode surface indirectly due to the evolved HClO. On the other hand, the microorganisms could reach the electrode surface in the low chloride suspension, adsorbed on it, and killed, i.e. the disinfection occurred due to the direct contact as well as HClO in the low chloride circumstance.