Method of operating spiral wound type membrane module

摘要

A spiral wound type membrane module is formed of a plurality of membranes wound about an axis of the module to form a roll of the membranes and to form feed water channels between the membranes into which feed water flows via a front end of the roll and from which nonpermeated water flows out via a rear end of the roll, wherein the module is operated such that a differential pressure between the feed water flowing into the channels and the nonpermeated water flowing out from the channels is 0.3 kg/cm2 or less. The pressure of the feed water is kept at PFmax or an approximate value of PFmax which brings a maximum permeate flux at the moment when a predetermined period has passed after starting to supply the feed water into the membrane module continuously at a constant pressure.