The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 18, 2003
Filed:
Jan. 20, 2000
Tetsurou Adachi, Ibaraki, JP;
Masaaki Andou, Ibaraki, JP;
Hajimu Hisada, Ibaraki, JP;
Tomomi Ohara, Ibaraki, JP;
Toshiyuki Kawashima, Ibaraki, JP;
Ichirou Kawada, Ibaraki, JP;
Nitto Denko Corporation, Osaka, JP;
Abstract
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.