In this study, we investigated the formation potentials of haloacetic acids (HAAs) in raw water and the behavior of HAAs in process waters and finished water during the high turbidity associated with typhoons and heavy rains and compared their behaviors under normal turbidity conditions. We also evaluated the effect of prechlorination time on HAA formation after the coagulation and sedimentation processes with raw water during the high turbidity events. As a result, the HAA formation potentials of raw water at high turbidity increased with an increase in total organic carbon. In case of high turbidity, the concentrations of HAAs, particularly dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA), in process water and finished water increased. The HAA formation potentials after coagulation and sedimentation processes decreased to the same levels as observed in the normal condition. The effect of prechlorination time in the coagulation and sedimentation processes on the HAA formation potentials was greater for TCAA than DCAA, which was more evident in the high turbidity condition.

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[in Japanese]

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[in Japanese]

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