| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device for inactivating microorganisms collected by sand filtering and restraining clogging due to the microorganisms by dissolving such a problem that the microorganisms such as Cryptosporidium, having tolerance to sterilization are accumulated in a high concentration in raw water during a back-washing water treatment, in a water treatment device using a sand filter tank. SOLUTION: A high voltage pulse is impressed across a pair or plural sets of confronting electrodes provided in the sand filter tank at a filtering time or a back-washing time. Since the voltage is preferentially impressed on suspension remaining on the filter sand and the microorganisms having moisture, the microorganisms are inactivated, and proliferation of the microorganisms is controlled and the microorganisms are killed, thus the clogging is suppressed.
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