In a spacer element for guiding a flow medium in apparatus for filtering and separating the flow medium by reverse osmosis and ultrafiltration wherein filter elements are disposed between adjacent spacer elements which are disc-shaped and each has a central opening with a plurality of spaced openings disposed around the central opening for conducting the flow medium through the spacer element, a plurality of projections extend from the surfaces of the spacer element and have support areas formed at their tops which are oriented essentially parallel to the side surfaces of the spacer element.