| 摘要 |
PROBLEM TO BE SOLVED: To provide a composite filter which can inhibit the filtration membranes of a membrane filter from becoming dry and hydrophobic, inhibit deterioration of membranes and filtration capacity due to impact of a backwash drain flow to the filtration membranes, and the like during the backwashing of a media filter tank, and reduce chemical cleaning cost for the filtration membranes. SOLUTION: The composite filter 7 incorporates a membrane filter 9 in a media filter basin 8. Partition walls 11, 11 are installed inside the filter basin 8 to form media filtration spaces 12, 12 between the partition walls 11, 11 and the inner wall 10a of the filter tank 10 in the filter basin 8. A water collecting passage 14b for filtered water is installed under the partition walls 11, 11, and a drain passage 16 for backwash drain of the filter tank 10 is installed over the water collecting passage 14b to form an installation space 18 for the membrane filter 9 over the drain passage 16. This enables backwashing of a filter material layer 13 while immersing a membrane module 9a in water H to be treated, and can prevent the bad influence on the membranes due to making them dry and hydrophobic. COPYRIGHT: (C)2007,JPO&INPIT
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