METHOD FOR FILTRATION WITH MEMBRANE

摘要

A method for filtration with membranes wherein ozone is added to original water (1) to treat the water with ozone (2) and thereby decompose suspended substances and organic substances contained in the original water and then filtration treatment (3) is carried out, which comprises controlling the amount of ozone to be injected to the original water on the basis of a flux of permeated water, a pressure of the inlet of a membrane module or an average inter-membrane pressure difference during filtration or backwash operation. Such control of the amount of ozone provides satisfactory quality of treated water and effective utilization of ozone, and thus leads to a high flux of filtered water with a small amount of ozone added. A flux of permeated water and a pressure of the inlet of a membrane module are measured by means of a flow meter (16) and a pressure gauge (13 or 15) respectively, and an average inter-membrane pressure difference is calculated from measured values of pressure gauges (13, 14 and 15).