| 摘要 |
PROBLEM TO BE SOLVED: To effectively wash a contaminated hollow fiber yarn membrane, in a method for washing a filter using a hollow fiber yarn membrane, by passing a washing liquid through the hollow fiber yarn membrane from the inside thereof to the outside thereof to expand the diameter of the hollow fiber yarn membrane by 1.5 times or more. SOLUTION: At a time of washing, permeated water is supplied to a filter 5 from a permeated water tank 9 through a valve 12 and an outlet line 6 by a backward washing pump 11 and further supplied to the inside of a hollow fiber yarn membrane from a permeated washing water outlet 6. The hollow fiber yarn membrane is expanded by the permeated water supplied from the inside and the pore size of the membrane becomes large and, at the same time, particles fixed to the inside of the membrane are removed by the flow of permeated washing water flowing from the inside of the membrane to the outside thereof. The permeated washing water containing particles falling from the membrane is discharged to the outside from a raw water inlet (in the vicinity of a valve 4) provided in a cover or from a conc. outlet 7. Permeated water is pure water and there is no possibility such that the membrane is recontaminated at a time of washing and a permeated water line is contaminated.
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