Embodiments of the present invention provide elements that are beneficial for use in fluid filtration. Embodiments provide elements that have variable feed spacer height, variable permeate spacer height, or both. The variable height allows flow properties to be matched to fluid volume as the filtration occurs.

Embodiments of the present invention provide for the deposition of spacing elements for spiral wound elements that prevent nesting of adjacent spacer layers and occlusion of feed space during element rolling.

A full-effect reverse osmosis membrane element includes a central tube and a reverse osmosis membrane assembly wound around the central tube. The reverse osmosis membrane assembly includes a pair of reverse osmosis membranes attached at front surfaces thereof and wound around the central tube. A water feed channel has a water inlet formed at front edges of the reverse osmosis membranes and a water outlet formed at rear edges of the reverse osmosis membranes. A water division structure is arranged in the water feed channel, and includes a first water division band forming a preset space with the central tube when the reverse osmosis membranes are in an unfolded state. The first water division band divides the water feed channel into a first flow channel having a gradually decreasing cross-section and a second flow channel in communication with the first flow channel.

A filter element comprises a membrane layer; and a feed spacer on the membrane layer, wherein the feed spacer comprises a plurality of unit cells arranged in three dimensions, wherein each of the plurality of unit cells comprises a cavity defined by a triply periodic minimal surface, and wherein the cavities of the plurality of unit cells are interconnected to allow a fluid to pass through the cavities of the plurality of unit cells.

A filter element comprises a membrane layer; and a feed spacer on the membrane layer, wherein the feed spacer comprises a plurality of unit cells arranged in three dimensions, wherein each of the plurality of unit cells comprises a cavity defined by a triply periodic minimal surface, and wherein the cavities of the plurality of unit cells are interconnected to allow a fluid to pass through the cavities of the plurality of unit cells.

Provided is a feed spacer having a three-layered structure, and a reverse osmosis membrane filter module including the same, where the feed spacer includes a first set of a plurality of strands that are positioned in parallel; a second set of a plurality of parallel strands provided to cross the first set; and a third set of a plurality of parallel strands positioned in parallel with a raw water flow direction, where at least one of the first set and the second set consists of strands having a smaller thickness than that of the strands constituting the third set.

Embodiments of the invention provide replacements for a continuous layer of feed spacer mesh in spiral-wound reverse osmosis elements and replacing such mesh with discrete regions of feed spacer supporting the inlet and outlet ends of the element and a stiffening bridge feature to bridge between these regions at the tail end of each membrane leaf comprising the element during the element rolling process. The stiffening bridge feature prevents inward deflection of the inner layer of the membrane leaf during rolling, facilitating proper sealing of the adhesive through the permeate carrier to the adjacent membrane film using known membrane rolling techniques.

Spiral wound reverse osmosis devices with reduced lateral leakage and thereby increased salt rejection are made by compacting a microporous layer within a composite reverse osmosis membrane longitudinally along its lengthwise periphery. Means and method for causing longitudinal indentations in composite membranes during manufacturing operations are disclosed and described.

A gas separation element comprising a membrane sheet and a permeate spacer, wherein the membrane sheet comprises a porous support and a discriminating layer, CHARACTERISED IN THAT: (a) the permeate spacer has an open space volume of at least 0.0004 m.sup.3/m.sup.2; and (b) the membrane sheet has an aspect ratio of at least 1.5.

Provided is a spiral membrane element that has a restricted outer diameter and is capable of being decreased in operation energy therefor. The element is a spiral membrane element including plural membrane leaves in each of which a permeation-side flow-channel member is interposed between opposed separation membranes a supply-side flow-channel member interposed between any two of the membrane leaves a perforated central pipe on which the membrane leaves and the supply-side flow-channel member are wound and a sealing part that prevents a supply-side flow-channel member from being mixed with a permeation-side flow-channel member. This element has an efficiency index E of 0.005 to 0.10, and the thickness of the supply-side flow-channel member is from 10 to 110 mil.