Operating method of reverse osmosis membrane unit

Abstract

A method for operating a reverse osmosis membrane device, the reverse osmosis membrane device comprising an aromatic polyamide reverse osmosis membrane, characterized in that: the aromatic polyamide reverse osmosis membrane has a permeate flux of pure water (RO permeate water) of 0.9 m3 / (m2·day) or higher when the effective pressure at the membrane surface is 2 MPa and the water temperature is 25°C, and the silica removal rate is 99.7% or higher, and / or the IPA (isopropanol) removal rate is 96% or higher, and / or the boron removal rate is 80% or higher, when the effective pressure at the membrane surface is 1 MPa, the water temperature is 25°C and the pH is 7.0, and the reverse osmosis membrane device is operated with a membrane differential pressure of 1.0 to 2.1 MPa.