Abstract: A flat-membrane separating arrangement has a plurality of separating blocks each having a packet of ring-shaped membrane-coated filter disks spaced from one another in an axial direction to form therebetween intermediate gaps which are open peripherally, assembling elements arranged to assemble the filter disks in the packet and including a plurality of spacing rings located between the filter disks and tensioning and permeate-guiding pins connecting the filter disks with one another, supplying elements for supplying raw solution or concentrate flow upstream of the packet of filter disks and including a plurality of curved guiding blades with a deflecting disk having a central projection at the side of the packet and with a first limiting member at the side opposite the packet, permeate-withdrawing elements including a second limiting member connected with the packet downstream of the latter and provided with a central opening for permeate withdrawal, and an annular wall extending along the supplying elements