Nitto Electric Industrial Co., Ltd.

Nitto-Denko Corporation

Hiroshi Iwahori

Akio Iwama

Yoshitaka Kazuse

Satoru Ishihara

Yuuji Yamashiro

Shigetoshi Matsumoto

Masahiko Hayashi

A seawater desalination method of the present invention includes the steps of: obtaining ultrafiltration membrane-treated water by subjecting seawater () to an ultrafiltration membrane treatment; obtaining membrane bioreactor-treated water by subjecting organic wastewater () to a membrane bioreactor treatment; obtaining mixed water by mixing the ultrafiltration membrane-treated water and the membrane bioreactor-treated water; obtaining ultraviolet irradiation-treated water by subjecting the mixed water to an ultraviolet irradiation treatment; and subjecting the ultraviolet irradiation-treated water to a reverse osmosis membrane treatment.

Seawater desalination method

A method for washing an inner surface of a tubular permeable membrane which comprises:

Method for washing inner surface of tubular permeable membrane

A selective permeable membrane and a process for preparing the membrane. The process comprises applying to a supporting substrate a membrane forming solution prepared by dissolving in an organic solvent a polyimide polymer comprising principally a repeating unit represented by the general formula (I): ##STR1## wherein R.sup.1 represents a divalent organic group, and a liquid swelling agent having a coagulation value with respect to the polyimide polymer of about 50 to about 200 and a boiling point of about 50.degree. C. to about 120.degree. C. under atmospheric pressure, evaporating at least a part of the swelling agent, and coagulating the polyimide polymer by contacting the polyimide polymer with a coagulating solvent which does not dissolve the polyimide polymer but is compatible with the organic solvent and the swelling agent.

Selective permeable membranes and process for preparing the same

Module and method for providing a safe treatment of noncondutive organic solutions containing inflammable solvents by passing such solutions under pressure through electrically conductive perforated tubes supporting membrane assemblies therein and being grounded through the case of the module.

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Osaka, Japan

Hiroshi Iwahori