| 摘要 |
PURPOSE:To obviate the deterioration in the back washing effect even after the filtration and back washing are repeated by keeping the flow velocity of a liq. permeating through a hollow yarn membrane from the inside to the outside in back washing at more than a specified value throughout each back washing state. CONSTITUTION:In the back washing stage of the hollow yarn membrane filter wherein a raw liq. permeates through the membrane from the outside to the inside, the pressure of the compressed air to be supplied into the hollow yarn membrane filter 1 from a compressed air supply pipeline 35 for back washing is progressively increased along with an increase in the differential pressure in each cycle to control the flow velocity of the liq. permeating through the hollow yarn membrane from the inside to the outside to more than a specified value. By this method, the fine particles collected on the surface of the hollow yarn membrane after filtration are removed to the same extent in each cycle, and the efficiency in back washing is not deteriorated.
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