| 摘要 |
PROBLEM TO BE SOLVED: To provide a cleaning method of a high recovery rate of suspended ingredients adhering to a separation membrane. SOLUTION: The method comprises the steps of supplying raw water from the lower entrance for raw water to a vertical separation membrane module having a lower entrance for raw water, an upper entrance for raw water and an outlet for permeated water to filter the raw water and then cleaning the membrane module by back pressure cleaning. When back pressure cleaning is carried out by supplying cleaning water from the outlet for permeated water and discharging from the lower and upper entrances for raw water, the ratio of the amount V<SB>2</SB>of cleaning water discharged from the upper entrance for raw water to the amount V<SB>1</SB>of cleaning water discharged from the lower entrance for raw water, V<SB>2</SB>/V<SB>1</SB>, is set to be higher than 1.0, and the time for one cleaning procedure is beyond 60 s. COPYRIGHT: (C)2007,JPO&INPIT
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