The present invention provides a method and apparatus for fabricating a separator assembly. The method comprises: providing a central core element comprising at least one concentrate exhaust conduit and at least one permeate exhaust conduit; disposing a first portion of a membrane stack assembly comprising a permeate carrier layer, a membrane layer, and a feed carrier layer within the central core element such that the concentrate exhaust conduit and permeate exhaust conduit are separated by the first portion of the membrane stack assembly; radially winding a second portion of the membrane stack assembly around the central core element; and sealing the wound assembly comprising two opposing end surfaces made of the membrane stack assembly by applying an adhesive on both end surfaces of the wound assembly; and applying a negative pressure inside the central core element so that the adhesive penetrates into the membrane stack assembly.