Disinfection of E. coli Cells by the Electrodialysis Disinfection System Employing Inorganic Cation Exchange Membranes

Makoto KOGURE*, Satoshi YASUJIMA†, Toshio SATO††, Takashi SUZUKI††† and Haruhiko OHYA

Department of Material Science and Chemical Engineering, Faculty of Engineering, Yokohama National University; 79-5 Tokiwadai, Hodogaya-ku, Yokohama-shi 240-8501 Japan
† Toho Titanium Co. Ltd; 3-3-5, Chigasaki, Chigasaki-shi 243-0041 Japan
†† Department of Environmental Eco Technology, Faculty of Life and Environmental Science, Shimane University; 1060, Nishikawatsu-cho, Matsue-shi 690-8504 Japan
††† Department of Applied Chemistry and Biological Technology, Faculty of Engineering, Yamanashi University; 4-3-11, Takeda, Kofu-shi 400-8511 Japan

The disinfection effect on Escherichia coli cells was investigated in the electrodialysis systems using the conventional organic cation exchange membranes (Selemion (R)CMV) and the antimony acid cation exchange membrane (Sb membrane) dippcoated on a microporous alumina support, which we previously synthesized. E. coli cells suspended in 0.1 M NaCl solution (108 cells cm-3) were passed through a desalting compartment at a flow rate of 3 cm3 min-1 under varying current densities, and survival ratio (%) in the effluents was measured. A pronounced decrease in the survival ratio of E. coli cells was observed for the inorganic membrane system at low current density compared with the organic membrane system. Complete disinfection was observed after 20 min of the electrodialysis at the current density of 13.6 mA cm-2, which was 1.4 times as high as the limiting current density of Sb membrane. Remarkable disinfection effect can be attributed to the formation of acidic H+ and basic OH- ions generated by the water dissociation on the desalting surface of Sb membrane because the limiting current density of Sb membrane was lower than that of Selemion (R)CMV.
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