Spirally wound membrane separator assembly

The present invention provides a separator assembly comprising a central core element comprising at least two permeate exhaust conduits and not comprising a concentrate exhaust conduit; and a membrane stack assembly comprising at least one feed carrier layer, at least two permeate carrier layers, and at least two membrane layers, the membrane layers being disposed between the feed carrier layer and the permeate carrier layers; wherein the permeate exhaust conduits are separated by a first portion of the membrane stack assembly, and wherein a second portion of the membrane stack assembly forms a multilayer membrane assembly disposed around the central core element, and wherein the feed carrier layer is not in contact with a permeate exhaust conduit, and wherein the permeate carrier layers are in contact with at least one permeate exhaust conduit. Also provided are salt separator assemblies and spiral flow reverse osmosis devices.