In Osaka City, we have introduced advanced water purification treatment by adding ozone and granular activated carbon treatment facilities to conventional treatment. In order to ensure safe and high quality tap water, research and studies on granular activated carbon have been conducted continuously. Compared to the introduction of advanced water purification treatment, changes in adsorption performance were observed in granular activated carbon delivered in recent years, with an increase in calcium adsorption with use over time. In addition, it is assumed that the suppression of calcium adsorption in the early stages of water flow and a structure that prevents the formation of acidic groups on the surface of granular activated carbon are necessary to maintain adsorption performance for a long period of time. Since the adsorption performance of granular activated carbon changes with the time of delivery, a uniform performance evaluation based on the number of years of use or water flow rate was not considered appropriate.

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[in Japanese]

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