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

Abstract

The disinfection effect on Escherichia coli cells was investigated in the electrodialysis systems using the conventional organic cation exchange membranes (Selemion^® 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 0.1MNaCl solution (10⁸ cells cm^-3) were passed through a desalting compartment at a flow rate of 3cm³min^-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 20min of the electrodialysis at the current density of 13.6mA 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^® CMV.