METHOD FOR PROCESSING BY REVERSE OSMOSIS MEMBRANE

PROBLEM TO BE SOLVED: To simplify pretreatment and to obtain the same level of the quality of processed water and permeation performance as the conventional one by performing the processing while air is mixed into raw water in a process for treating sand-filtered raw water by passing it through a reverse osmosis membrane for processing waste water and industrial waste water by utilizing the reverse osmosis membrane. SOLUTION: In a method wherein the secondarily processed water of a waste water or an industrial waste water is used as a raw water and it is highly processed by using a reverse osmosis membrane, a processing apparatus 7 constituted by providing a sand filtering device 2 for pretreatment of the raw water 1, an air mixing hole 4a for mixing air 4 into the raw water 3 filtered by means of this sand filtering device 2 and a spirally shaped reverse osmosis membrane 6 in which a spacer for widening a raw water flow path is thickened, is used. In adition, in a process wherein the sand- filtered raw water 3 is processed by passing it through the reverse osmosis membrane 6, the raw water is processed while air 4 is continuously or intermittently mixed into the raw water 3. In this case, mixing of the air 4 is pref. performed intermittently. In addition, the amt. of the air 4 is regulated to about 20% of the amt. of the raw water to be fed.