| 摘要 |
PURPOSE:To reduce the amt. of waste liquid of backwashing and to shorten the necessary working time for backwashing by precipitating impurities stripped off the surface of a hollow yarn filtration membrane by the effect of backwashing using pressurised fluid to a storing part of the impurities at the bottom of a filtration chamber and by commencing filtration of the liquid to be treated at this stage. CONSTITUTION:When waste liquid, etc. in a waste product treating system of a nuclear power plant is filtered and pressure drop between the outlet and inlet 18, of a filtration tower 10 reaches a regulated value by the accumulation of captured impurities on fine pores of the hollow yarn filtration membrane 26, valves 20, 32, 38, 47, 49 are closed and a valve 46 in a line of pressurized water 44 is opened to exert the pressure of the pressurized water to strip off the impurities captured by the filtration membrane 26, and the impurities are precipitated in a storing part 29 of the impurities at the bottom of the filtration tower 10. After applying back pressure for a fixed time by the pressurized water, the valve 46 is closed, and the inlet valve 20 and the outlet valve 38 of the filtration tower 10 are opened to commence filtration for the the waste liquid.
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