| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for cleaning a separation membrane of an out-of-basin type for filtering tank water in a biological treatment tank by filtration without using a large amount of a chemical solution, and without damaging microorganisms in the biological treatment tank. <P>SOLUTION: When the out-of-basin type separation membrane 2, which is connected to the biological treatment tank 1 through a circulation passageway 5 for filtering the tank water, is cleaned, a part or all of backwash drainage containing sludge peeled from the membrane surface is returned to the biological treatment tank 1 through a backwash drain passageway 14 or the circulation passageway 5 to maintain MLSS of the biological treatment tank 1 constant, in the case of usual backwash with water. In the case of chemical cleaning, the sludge is peeled from the membrane surface by backwash with water, and the sludge is discharged out of the membrane module through a sludge line 16 and then followed by chemical cleaning. Thus, since the need for using a large amount of the chemical solution is eliminated and the peeled sludge containing the chemical solution can be discharged out of the system as well, the microorganisms are prevented from being damaged by the chemical solution. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
