Abstract: An improved spiral wound element for separations is disclosed wherein the improvement comprises using as the feed/retentate space one or more layers of a material having an open cross-sectional area in the range 30 to 70% and as the permeate spacer material at least three layers of material two of which are fine and have an open cross-sectional area of about 10 to 50% surrounding a coarse layer having an open cross-sectional area of about 50 to 90%.

Abstract: Self-standing apparatus for filtering supply water to provide purified water includes a base subassembly and two container subassemblies. One container subassembly provides supply water to filtering apparatus located in the base subassembly. The second container holds purified water which passes through a semipermeable membrane filter in the base subassembly. Concentrate from the membrane filter flows back to the supply water container for ultimate recirculation. The base subassembly and the container subassemblies have automatically closing valves which render each container water-tight when separated from the base subassembly, and which open to provide communication between the containers and filtering apparatus within the base subassembly.

Abstract: A spiral wound membrane cartridge for use in separating a first component from a feed fluid mixture of the first component and the second component. The cartridge includes a permeate collection tube and at least one permeate carrier leaf extending outwardly from the tube. The cartridge further includes at least one sandwich leaf extending outwardly from the tube and including a length of a semipermeable membrane sheet which has an active membrane side and a backing side. This sheet is folded in two, having the fold positioned adjacent the tube and with the membrane sides of the two parts of the folded sheet facing. The sandwich leaf also includes a length of a feed carrier positioned between the two parts of the folded membrane sheet.

Abstract: A reverse osmosis membrane with excellent nitrate rejection that is particularly suitable for point-of-use drinking water purposes. The reverse osmosis membrane is a composite material comprising a porous support layer and an ultrathin polyamide desalinizing layer which is the interfacial condensation reaction product of (a) meta-phenylenediamine and (b) a mixture of a major portion of isophthaloyl chloride and a minor proportion of trimesoyl chloride.

Abstract: A water purification system having a first pressure vessel containing a reverse-osmosis filter and a second separate pressure vessel containing an activated carbon prefilter operatively connected in series and upstream of the first pressure vessel by means of a common header. The activated carbon prefilter includes a particulate trap upstream of the activated carbon to trap sediment carried in the unpurified water. The particulate trap is compressible under operational water pressures attained in the system when the trap becomes clogged with sediment, which serves to crack or break away from the surface thereof particle accumulations clogging the trap, permitting flow to continue through the trap into the activated carbon and, subsequently, through the reverse-osmosis filter element.

Abstract: An over-the-counter, free-standing, water purification system including a pressure vessel that encloses a reverse-osmosis separator. Tap water at a pressure of between approximately 20 and 100 psig is introduced into the pressure vessel and a portion of the water is forced through the reverse-osmosis separator, while the remaining water is discharged from the pressure vessel along with the pollutants that are too large to penetrate the membrane of the reverse-osmosis separator. The product water passes through the reverse-osmosis separator at a rate of between approximately 5 to 100 milliliters per minute and is then post-filtered at a slow rate through a large amount of activated carbon, between approximately 10 and 1,000 grams, contained within the housing for the purification system.

Abstract: An improvement in a membrane cartridge for insertion into a pressure-resistant container and having a central passageway holding a permeate collection tube. A cartridge is formed, at least in part, by a spiral winding of a laminate leaf comprising semipermeable membrane sheet material, permeate transfer sheet material, and porous grid sheet material. An extension on the leaf of the porous grid material is of sufficient length to encompass the circumference of the cartridge when the cartridge is positioned inside the container. The cartridge may have an outer wrapping of water-soluble sheet material.

Abstract: A reverse osmosis system including a proportioning flow control, for controlling brine flow from a pressure resistant vessel containing a membrane cartridge, which has ends of two small diameter duct portions enclosed inside a hollow body, which is separate from the pressure resistant vessel containing the membrane cartridge. Means, such as a unitary mass of solidified epoxy adhesive, seals the passage of each of the duct portions through a wall of the hollow body and leaves space within the hollow body with which the open ends of the small diameter duct portions communicate and which itself communicates with a relief valve connected to a collector or tank for storage of permeate from the membrane cartridge under elevated pressure.

Abstract: A semipermeable membrane cartridge is reciprocated within a pressure resistant vessel to provide improved liquid flow and turbulence over the semipermeable membrane surfaces. The end of the semipermeable membrane cartridge exposed to the pressure of feed liquid introduced into one end of the pressure resistant vessel is adjusted or arranged to be of substantially the same effective cross sectional area as that of the end of the cartridge exposed to the pressure of brine being released from the other end of the pressure resistant vessel. This essentially balances the liquid pressure forces on the ends of the semipermeable membrane cartridge to provide improved conditions for reciprocation.

Abstract: A reverse osmosis system employs a tank for storing permeate under a pressure which is a portion of the pressure of feed water introduced into a pressure resistant container housing a semipermeable membrane cartridge. Control means such as an automatic valve, preferably of the double diaphragm type, in the line introducing feed water into the pressure resistant container closes to shut off feed water flow when the pressure in the permeate storage tank reaches a first predetermined value, less than the feed water pressure, and re-opens to re-establish feed water flow at a second predetermined pressure lower than the first or shut-off pressure. A constricted passageway device such as a venturi in the pipe or connection between a dispensing device such as a faucet and the permeate storage tank has its throat communicating with the sensing conduit for actuating the feed water control valve.

Abstract: A process for recovery of fresh water by reverse osmosis from high salt content feed, such as sea water, comprises treating the feed water in an initial stage at relatively low pressure (between about 300 and 550 psi) employing a loose semipermeable membrane, to produce an intermediate product water containing one-fourth to one-half the TDS (total dissolved solids) content of the original feed water. The intermediate product water is treated in a subsequent stage also at a relatively low pressure (between about 300 and 550 psi) employing a tight semipermeable membrane, to produce a fresh product water containing less than 2,000 ppm TDS, and preferably a potable water containing less than 1,000 ppm TDS.

Abstract: A spiral wound reverse osmosis or ultrafiltration membrane cartridge has a central collection tube fabricated from a plurality of interlocking segments; the center segments are perforated and the segment at each end is imperforate. The side edges of the cartridge membrane leaves and the permeate transfer sheet are sealingly attached to the central collection tube by circumferential bands of glue located outboard of the juncture of the imperforate end segments with adjacent perforate center segments. Substantial fabrication economies result from injection molding the center segments as identical bodies from a single die; and injection molding the end segments also as identical bodies from a single die.

Abstract: An improved spiral wound reverse osmosis or ultrafiltration membrane cartridge has the inner end and side areas of a permeate transfer leaf sealingly attached to its central collection tube surface, with sealing adhesive applied as band areas near each side edge of the proximate transfer leaf surface in amount in excess of the amount to substantially fill a pair of circumferential grooves in the collection tube when the assembly, including the permeate transfer leaf is spirally wound around it. The adhesive seal is preferably cured at room temperature with the cartridge standing on one of its ends for a period of about 12 to 24 hours. In an alternative embodiment, resilient O rings may be seated in the collector tube grooves, and an additional pair of grooves within the side band areas may also be filled with adhesive.

Abstract: A reverse osmosis system which includes a purified water storage tank, has a by-pass pipe around the concentrate flow control of its membrane module and a normally closed valve in the by-pass pipe. The by-pass pipe valve is opened automatically when purified water is withdrawn from the purified water storage tank, thereby to flush feed water through the membrane module.

Abstract: A reverse osmosis system having a tank for storing purified water includes a valve in the pipe which introduces feed water into a module containing a semipermeable membrane and which produces the purified water. The valve shuts off or turns on introduction of feed water into the module in response to the weight of purified water in the storage tank.