J. SASJ, Vol. 39, No. 2 2008. 9, 141-146
Strong acid electrolyzed water (SAcEW) is known to contain hypochlorite which has shown to have a strong bactericidal effect. Therefore it has been authorized by the Ministry of Labor and Welfare as medical device for hand washing and food additive in Japan. It is expected as an alternative means for the strong agricultural chemicals currently being used in agriculture field. Underground water is mainly used to produce electrolyzed water in realm of agriculture. Because of various ions is included; it has an effect in the pH buffering in making SAcEW. Therefore, the influence of the resource water's quality on the bactericidal effect of Strong Acid Electrolyzed Water (SAcEW) was studied. The water used as raw material was adjusted to mimic the quality of Japanese ground water in terms of alkalinity by the use of NaHCO3. In this paper, the correlation between the concentration of carbonate ions and pH of SAcEW was examined, and it was in confirmed this study that when the content of the carbonate ion exceeds 68mg/L, the pH of generated SAcEW exceeds regulated upper bound (pH 2.7). The pH rose to 3.3 when the resource water's carbonate ion concentration was raised to 150mg/L, the quality which is similar to the water quality of resource water used in Japan and the results were compared with that of pure water that was confirmed pH 2.5. At the same concentration of available chlorine, SAcEW with pH 3.3 showed faster sterilization speed on E. coli than at pH 2.7.
Therefore, the authors suggest that pH changes from the legal value (pH 2.5±0.2) to pH 3.3 resulting from the use
of carbonate ion included water such as underground water would not affect the sterilization speed of SAcEW on E. coli,