Abstract: A tubular membrane, a membrane module, a device including a number of such membranes, and a method for manufacturing such membranes. The tubular membrane includes a tubular base providing a support and having an inner and outer surface, where the tubular base defines a lumen for the feed flow, and a membrane layer provided on the inner surface of the tubular base, where the inner surface of the tubular membrane includes a number of inwardly projecting ridges that extend in a substantially longitudinal direction of the tubular membrane.

Abstract: A method for processing a fluid with forward osmosis process includes providing one or more tubular membranes each including a tubular nonwoven base layer on the outside of the tubular membrane forming an outer shell of the tubular membrane and providing a lumen for feed flow; a polymer substrate layer on the lumen-side of the tubular membrane comprising three regions, including a region where the polymer substrate layer is partially intruded into the tubular base layer, a region with an open macrovoid structure and a region with an asymmetrical foamy layer, where the partially intruded region forms an intermediate layer; and a functional top layer on the polymer substrate layer. The tubular base layer comprises a longitudinal weld. The method includes providing the feed flow through the lumen and providing a draw solution on the outer shell side of the tubular membrane; and processing the feed flow with the membrane.