Patent ID: 6878294
Filing Date: 2005-04-12
Classification: B01D,C02F

Abstract:
1. A method of running a spiral wound membrane element, comprising an envelope separation membrane wound on the outer peripheral surface of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa, comprising a step of injecting gas of not more than 0.3 MPa from at least one opening end of said perforated hollow pipe as recovery of a filtration velocity, wherein said step of injecting gas includes a step of axially feeding a raw liquid through said spiral wound membrane element in combination with said step of injecting gas as recovery of a filtration velocity, and wherein said step of axially feeding a raw liquid includes a step of returning at least part of said raw liquid axially fed through said spiral wound membrane element to a feeding side of said spiral wound membrane element again.