METHOD FOR CLEANING MEMBRANE FILTRATION APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a method for efficiently backwashing a filtration membrane for membrane-filtering external circulating water from a biological treatment tank by water in a short time or a method for efficiently cleaning the filtration membrane by a liquid chemical in a short time.

SOLUTION: When the differential pressure of the membrane in a membrane filtration apparatus 2 for membrane-filtering the external circulating water withdrawn from the biological treatment tank 1 is increased, the membrane is cleaned by any one of the below-mentioned two methods. A first method for backwashing the membrane by water comprises a step of fluidizing a liquid on the primary side of the membrane by a gas to exfoliate/remove attachments on the surface of the membrane while making washing water flow from the secondary side of the membrane toward the primary side. A second method for cleaning the membrane by the liquid chemical comprises the steps of: immersing the whole surface of the membrane in the liquid chemical by making the liquid chemical flow from the secondary side of the membrane toward the primary side; and fluidizing the liquid on the primary side of the membrane by the gas to dissolve/remove adherent material on the surface of the membrane.

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