Improvement of Water Quality Using a Magnetic Ion Exchange Resin at Drinking Water Treatment Plant on Chichijima Island in Ogasawara Village

Abstract

Because the concentrations of, for example, trihalomethane (THM) , and dissolved organic matter (DOM) in the drinking water of Ogasawara Village were high, a magnetic ion exchange resin (MIEX^®) system was applied for the first time in Japan in an actual drinking water treatment plant, in the new water treatment plant constructed on Chichijima Island. The introduction of the MIEX^® system after the conventional coagulation system was, until then, unprecedented. The objective in this study is to verify the effect of the MIEX^® system. The removal rates of THM and haloacetic acid (HAA) precursors, DOC and other substances rose at this plant. The molecular weight of DOM in the source water decreased with activated carbon -coagulation and additional MIEX^® treatment processes. The concentrations of THM and HAA in tap water from the new water treatment plant decreased to less than half the values in water from the previous water treatment plant. The target values of THM and total organic carbon in the design stage of the plant at Ogasawara Village were achieved.