Method, equipment and specific drawer for membrane separation utilizing concentration polarization

A membrane separation method, comprising:

• a) loading a fluid containing a retention component and a permeation component at a separation side of a separation membrane;
• b) exerting a driving force on said fluid to allow at least part of said permeation component to pass through said separation membrane and arrive at a permeation side of the separation membrane, thereby forming a retention component-enriched concentration polarization layer at said separation side of said separation membrane;
• and c) removing at least part of said concentration polarization layer from said separation side by means of a drawer to obtain concentrated retention components, wherein said drawer comprises a hollow pipe structure having at least one opening, a section with an opening of said hollow pipe structure is over a feed-side surface of said separation membrane, said opening configured to face said feed-side surface of said separation membrane and be located inside said concentration polarization layer at the separation side of said separation membrane such that at least part of said concentration polarization layer passes through said opening into said hollow pipe structure, and is removed from said separation membrane along a direction essentially normal to the separation membrane.