Nitto-denko Corporation

Ichirou Kawada

Toshiyuki Kawashima

Hajimu Hisada

Masaaki Andou

Tomomi Ohara

Tetsurou Adachi

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

An active carbon cartridge is provided in the preceding stage to a fresh water generating cartridge. A water feed valve is connected to a raw water inlet of the active carbon cartridge. A bypass pipe is connected to bypass the water feed valve and the active carbon cartridge, and a bypass valve is inserted in the bypass pipe. A flushing valve is provided on the fresh water generating cartridge. A timer controls opening and closing of the bypass valve and the flushing valve. The bypass valve as well as the flushing valve are periodically opened during interruption of fresh water generation work with the fresh water generating cartridge or during fresh water generation work, or opened simultaneously with interruption of fresh water generation work or when restarting fresh water generation work.

Fresh water generator and fresh water generating method

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

A wash water pipe having a flushing valve inserted therein is connected with a concentrated water outlet pipe connected to a concentrated water outlet of a fresh water generating cartridge. A timer controls opening and closing of the flushing valve. The flushing valve is periodically opened during interruption of fresh water generation work with the fresh water generating cartridge or during fresh water generation work, or opened simultaneously with interruption of fresh water generation work or when restarting fresh water generation work, for performing flushing. Thus, the linear velocity on the surface of a reverse osmosis membrane of the fresh water generating cartridge is increased and impurities remaining on the membrane surface are discharged from the fresh water generating cartridge.

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Ibaraki, Japan

Ichirou Kawada