An electrolyzing system integrated into a warm water bidet system (Washlet®) is characterized by producing the Japanese tap water quality-keeping electrolyzed water with elevated available chlorine concentration (ACC: <5mg/L). As a prerequisite to ensure the steady production of this electrolyzed water, we surveyed the qualities of large numbers of tap waters nationwide (5,805 waterworks covering 47 prefectures). Consequently it turned out that over 90% of them showed the restricted ranges of scores in terms of pH, chloride ion (Cl^－) and organic substance: i.e. pH6.9-7.7 (standard range 5.8-8.6), Cl^－ concentration of <50 mg/L (standard range <200mg/L), organic substance concentration of <1 mg/L (standard range <3 mg/L). Since these factors may influence the quality of the electrolyzed water produced, we analyzed the qualities of the electrolyzed waters made from 8 selected tap waters including ones with the highest as well as average levels of pH, Cl^－ and organic substance. It turned out that all of the resulting electrolyzed waters with specific ACC elevation kept the water qualify of Japanese standards as well as WHO guideline. Therefore, it was conclusive that the electrolyzing system would work steadily to produce the electrolyzed tap water with domestic and international tap water qualities as well as good bacteria-killing activity.

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A tap water derived electrolyzed water that is remarked by specifically-elevated available chlorine concentration (ACC: <5mg/L) is examined for the stability of its properties during preservation under closed as well as open conditions. Under the closed condition, ACC decreased slowly at a constant rate regardless of its initial concentration. The initial ACC of 1 and 2mg/L decreased to the tap water level (0.2mg/L) after 1.5 and 4 months, respectively. In case of the initial ACC of 4.5mg/L, however, it remained at 1mg/L even after 8 months in spite of the decrease of half of the initial ACC after 3 months. The water qualities of electrolyzed waters of which ACC returned to the tap water level was within the range of Japanese water quality standards as well as WHO guideline. Under the open condition, about 2mg/L of initial ACC decreased to the tap water level in about 90min. in case of a small amount (about 15mL in a petri dish) of the electrolyzed water, whereas 24hr was needed for a large amount (800mL with stirring in a 1L vol. beaker) of the electrolyzed water. The resulting water showed quality in the range of Japanese tap water quality as well as WHO drinking water guideline. Concerning the electrolyzer (electrode) durability, continuous repeated use resulted in a steady decrease in electro-currency and ACC productivity. The electro-currency of 0.38A and ACC productivity of 1.5mg/L at the beginning decreased to 0.2A and 0.8mg/L after 450hr continuous use and to 0.03A and 0.3mg/L after 600hr continuous use, indicating the lifespan of the electrode. The water passed through the 600hr continuously used electrode showed the water quality equivalent to that of Japanese tap water.

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Using slightly-acidic electrolyzed water (SAEW) known as a food additive hypochlorous acid water, we established a new effective method for washing and decontaminating “Sake” filter cloths. In this method, the cloths are subject to preliminary washing with SAEW, followed by washing with a cleansing agent-added SAEW and then triple rinsing with SAEW. After each procedure, microscopic check of cloth surface, microbiological check as well as available chlorine concentration check are carried out. Consequently it turned out that this new washing method is a very effective Sake filter cloth reprocessing method.

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We compared and studied the active oxygen-scavenging ability of hydrogen rich water. We evaluated the scavenging abilities of hydroxyl radical, superoxide, and singlet oxygen, on the hydrogen water samples which were in the market from December 2015 to March 2016 by the spin trapping method using an electron spin resonance apparatus. As a result, we found that there was relationship between the ability to scavenge hydroxyl radical and the hydrogen concentration in the hydrogen water samples. On the other hand, there was no relationship between the ability to scavenge superoxide and that to scavenge singlet oxygen. It was suggested that hydrogen molecule in hydrogen water undergoes neutralization specifically with the hydroxyl radical among active oxygen species. Dissolved hydrogen content decreased with time when hydrogen water samples obtained from the market were left exposed to the atmosphere. Hence, it is necessary to pay attention, after opening on every sample, to observe the designated preservation method and to drink off the water before the discharge of hydrogen into air.

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