Bureau of Waterworks Tokyo Metropolitan Government has been conducted a survey of the detection status of enteric viruses in raw water, settled water and purified water at its purification plants since 2006. In the survey so far, enteric viruses above the theoretical quantification limit were detected only in raw water at the purification plants in the Edogawa and Arakawa River systems. Therefore, the raw water in these purification plants is more likely to be contaminated with enteric viruses than in the others. On the other hand, the virus was not detected in the purified water at any of the purification plants surveyed, confirming that the viruses had been removed by the water treatment process. In addition, we investigated the electronegative membranes used for virus concentration were compared between the conventional flat-type membranes and cartridge-type membranes, and changed to the cartridge-type membrane from 2018, which is superior in terms of simplicity of operation and theoretical quantification limit.

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