MEMBRANE USED AS A COMPOSITE MEMBRANE FOR THE SEPARATION OF DISSOLVED AND SUSPENDED SUBSTANCES AND DISSOLVED SALTS FROM THEIR CARRIER LIQUID

摘要

The invention relates to a membrane that is used as a composite membrane for the separation of dissolved and suspended substances and dissolved salts from their carrier liquid. Said membrane consists of a flat substrate with relatively wide through-flow openings on which a separating layer is applied that consists of a composite of a granular filler and a binder. The inventive separating layer consists of at least two superimposed interlinked constructional layers of different structure. The superimposed constructional layers applied on the substrate contain respective graded sequences of filler ratios and correspondingly higher binder ratios as compared to a preceding constructional layer. When the membrane is operational and fitted in a separation installation, the separating layer is oriented in such a manner that the constructional layer with the lowest filler ratio is impinged by the liquid that contains the substances to be separated. The inventive membrane structure allows a substantial reduction of the inner resistance to flow of the membrane. At the same time, a high flux can be achieved at a relatively low transmembrane pressure and a relatively low overflow rate.