Nitto-denko Corporation

Other

Masaaki Andou

Ichirou Kawada

Hajimu Hisada

Tomomi Ohara

Masahiko Hirose

Hisao Hachisuka

Craig R Bartels

Toshiyuki Kawashima

Mark Wilf

Terutaka Watanabe

Keith Andes

Tetsurou Adachi

In the treatment, a reverse osmosis membrane element having a polyamide skin layer is loaded in a pressure vessel in a membrane separator and contacted with a bromide-containing aqueous solution of free chlorine. The thus treated reverse osmosis membrane element retains for a long time its effect of reducing solute concentration in a solution treated with the reverse osmosis membrane and rejects efficiently non-electrolytic organic materials or substances such as boron that will not be dissociated in a neutral region. A reverse osmosis membrane module having the thus treated reverse osmosis membrane element is provided as well.

Method of treating reverse osmosis membrane element, and reverse osmosis membrane module

A spiral wound type membrane element is formed by covering a spiral membrane component prepared by winding a plurality of independent or continuous envelope-like membranes around the outer peripheral surface of a water collection pipe through raw water spacers with a separation membrane and further covering the same with an outer peripheral passage forming material. In filtration, raw water introduced from a raw water inlet of a spiral wound type membrane module permeates through the separation membrane from at least the outer peripheral side of the spiral wound type membrane element and infiltrates into the clearances between the envelope-like membranes along the raw water spacers. Part of the supplied raw water axially flows along the outer peripheral portion of the spiral wound type membrane element and is thereafter discharged from a raw water outlet of the spiral wound type membrane module, to be returned to a raw liquid tank again. Back wash reverse filtration is performed in washing of the spiral wound type membrane element. The permeate flow rate in filtration, the filtration time, the wash water flow rate in washing and the washing time are set to prescribed values so that the permeate volume in filtration to the permeate volume in back wash reverse filtration is not more than 600.

Methods of running and washing spiral wound membrane modules

A spiral wound membrane element is formed by covering a spiral membrane component prepared by winding a plurality of independent or continuous envelope-like membranes around the outer peripheral surface of a water collection pipe through raw water spacers with a separation membrane and further covering the same with an outer peripheral passage forming material. In washing, permeate containing a chemical is introduced from an opening end of the water collection pipe while the permeate derived from the outer peripheral surface of the water collection pipe is discharged from at least the outer peripheral side of the spiral wound type membrane element and raw water is axially fed along the outer peripheral portion of the spiral wound type membrane element. In filtration running, the raw water in which bubbles are diffused by an air diffuser may be supplied to the spiral wound membrane element stored in a pressure vessel. Alternatively, filtration running may be temporarily stopped for holding the spiral wound type membrane element for a prescribed time in a state sealing the raw water and the permeate in the pressure vessel.

Methods of running and washing spiral wound membrane module

In a treatment system, a spiral wound type membrane module is provided on a preceding stage of a reverse osmosis membrane separation device for performing pretreatment with the spiral wound type membrane module. The spiral wound type membrane module is formed by charging a pressure vessel with a spiral wound type membrane element. The spiral wound type membrane element is formed by covering a spiral membrane component, prepared by winding a plurality of independent or continuous envelope-like membranes on the outer peripheral surface of a water collection pipe, with a separation membrane and further covering the same with an outer peripheral passage forming member.

Treatment system and treatment method employing spiral wound type membrane module

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Ibaraki, Japan

Masaaki Andou