Showing papers on "Reverse osmosis published in 1990"
TL;DR: A portable reverse osmosis (RO) system was constructed and used to concentrate dissolved organic matter (DOM) from the Suwannee River in southeastern Georgia as mentioned in this paper, where a very high percentage of DOM was recovered, which indicates minimal fractionation of the original sample.
282 citations
Patent•
24 Jul 1990
TL;DR: An ultraviolet driven photocatalytic post-treatment technique for the purification of waste water distillates, reverse osmosis permeates and spacecraft habitat atmospheric humidity condensates is described in this paper.
Abstract: An ultraviolet driven photocatalytic post-treatment technique for the purification of waste water distillates, reverse osmosis permeates and spacecraft habitat atmospheric humidity condensates is described. Experimental results show that organic impurity carbon content of simulated reclamation waters at nominal 40 PPM level are reduced to, PPB using a recirculating batch reactor. The organic impurities common to reclaimed waste waters are completely oxidized employing minimum expendables (stoichiometric oxygen). This paper discusses test results and parameteric data obtained for design and fabrication of a bread-board system. The parametric testing includes UV light source evaluation, photolysis vs photocatalysis comparison, oxygen concentration dependence, temperature dependence, reactor mixing, disinfection features, photocatalyst loading, photocatalyst degradation studies and power consumption estimates. This novel post-treatment approach for waste water reclamation shows potential for integration with closed-loop life support systems.
63 citations
58 citations
Patent•
03 Aug 1990
TL;DR: In this article, a manifold is formed with a main gallery passage which is subdivided into a succession of bores of progressively increasing diametric size, with adjacent bores being separated by transition segments of uniform thread pitch, and appropriate threading plugs and/or check valves are installed along the gallery passage to regulate water flow in series through the reverse osmosis and filter cartridges to separate the tap water supply into the relatively purified water supply and a reject water supply having impurities concentrated therein.
Abstract: A reverse osmosis water purification system is provided for removing contaminants from a tap water supply or the like, to produce a relatively purified water supply. The system includes a header manifold formed as a unitary component and adapted to receive and support a plurality of removable cylindrical canisters having a reverse osmosis cartridge and associated filter cartridges installed therein. The manifold is formed with a main gallery passage which is subdivided into a succession of bores of progressively increasing diametric size, with adjacent bores being separated by transition segments of uniform thread pitch. Appropriate threading plugs and/or check valves and the like are installed along the gallery passage to regulate water flow in series through the reverse osmosis and filter cartridges to separate the tap water supply into the relatively purified water supply and a reject water supply having impurities concentrated therein. The manifold further connects the purified water supply to an appropriate storage vessel and/or for dispensing via a faucet valve or the like, and discharges the reject water supply to a drain. Each of the cylindrical canisters is easily removed from the manifold to facilitate periodic replacement of the reverse osmosis or filter cartridges contained therein.
52 citations
Patent•
16 Mar 1990
TL;DR: Hybrid membrane-based separation systems, useful in separating solvents and solutes, are disclosed in this article, in which there is combined any of the solvent removal processes reverse osmosis, nanofiltration, membrane, distillation and pervaporation with any one or more of the solute removal processes utilizing superspaporation membranes, supported liquid membranes, coupled transport membranes, and membrane contactors.
Abstract: Hybrid membrane-based separation systems, useful in separating solvents and solutes, are disclosed in which there is combined any of the solvent removal processes reverse osmosis, nanofiltration, membrane, distillation and pervaporation with any one or more of the solute removal processes utilizing pervaporation membranes, supported-liquid membranes, coupled transport membranes, and membrane contactors. The solvent and solute removal processes are arranged to form part of a recycle stream that utilizes membrane separation retentates as feeds and as recycle feed stream make-up.
50 citations
TL;DR: In this article, the energy consumption of simulated textile processes have been analyzed and compared with systems where membrane technologies have been introduced, and the value of dye and salt concentration which might be reached have been tested in a reverse osmosis pilot plant.
47 citations
Patent•
11 Apr 1990
TL;DR: Semipermeable composite membranes composed of a porous substrate and at least two layers of film-forming polymers coated thereon are provided, which show good mechanical, physical and chemical stabilities and are useful in reverse osmosis and ultrafiltration processes, particularly for desalting solutions of low molecular weight organic compounds as mentioned in this paper.
Abstract: Semipermeable composite membranes composed of a porous substrate and at least two layers of film-forming polymers coated thereon are provided, which comprise a first layer of monomeric or polymeric diazonium salts, which have been reacted with themselves and with an at least difunctional compound, and a second layer, which is chemically bonded to the first one, of a cross-linked, ionically charged hydrophilic polymer. The membranes show good mechanical, physical and chemical stabilities and are useful in reverse osmosis and ultrafiltration processes, particularly for desalting solutions of low molecular weight organic compounds.
47 citations
TL;DR: In this paper, the effective charge density and the membrane structure, that is, membrane thickness, tortuosity and the water content, are determined from measurement of the membrane potential and compared with those obtained from other experiments.
Abstract: In the transport equation of charged ulfrafiltralion and reverse osmosis membranes which we proposed previously, the effective charge density and the membrane structure, that is, membrane thickness, tortuosity and the water content, are important transport parameters.In this study, these two parameters as determined from ultrafiltration experiments by using the previously proposed transport equation were compared with those obtained from other experiments. The effective charge density was determined from measurement of the membrane potential. It was strongly affected by the feed concentration and agreed well with that obtained from the filtration experiments. Moreover, the membrane structural parameter determined from filtration experiments was compared with that obtained from diffusion experiments. The two values showed good agreement.The measurement of membrane potential and the diffusion experiments were found to be useful for predicting the transport parameters of charged ultrafiltration membranes.
45 citations
Patent•
23 Feb 1990
TL;DR: In this paper, a compact, high flow rate reverse osmosis water filtration system suitable for home use has four primary operating components, including a carbon sediment pre-filter assembly, a reverse Osmosis filter assembly, granulated activated carbon post-filter assemblies, and a flow controller.
Abstract: A compact, high flow rate reverse osmosis water filtration system suitable for home use has four primary operating components--a carbon sediment pre-filter assembly, a reverse osmosis filter assembly, a granulated activated carbon post-filter assembly, and a flow controller. These four components are operatively interconnected by lengths of flexible tubing provided with finger operable quick disconnect fittings which permit each element to be rapidly disconnected from and reconnected to the balance of the system without the use of tools of any sort. Each of the three filter assemblies is of a throw-away construction comprising a filter material permanently sealed within a housing structure. Filter changeout is thus easily and quickly achieved by the homeowner simply by disconnecting the particular filter assembly and discarding it, housing and all, and then quickly reconnecting a replacement filter assembly in the system. A specially designed combination water supply/rinse water discharge fitting is utilized to operatively connect the system to a sink faucet, and a high purified drinking water production rate is achieved utilizing a rolled, double wrapped filter membrane structure in the reverse osmosis filter assembly.
43 citations
Patent•
06 Jun 1990
TL;DR: A membrane process for producing an improved product quality comprising feeding a clarified serum at an elevated pressure to a plurality of reverse osmosis units in two stages is described in this paper.
Abstract: A membrane process for producing an improved product quality comprising feeding a clarified serum at an elevated pressure to a plurality of reverse osmosis units in two stages - the first having high-rejection polyamide membranes and the second having low-rejection membranes, wherein the permeate from the low-rejection membranes is recycled to the high-rejection feed.
36 citations
Patent•
20 Mar 1990TL;DR: In this article, a reverse osmosis water purification system has a feed water line and outlets for reject and product water, and a section of the water feed line has a flow restrictor which estabishes a dynamic pressure drop.
Abstract: A reverse osmosis water purification system has a feed water line and outlets for reject and product water. Instead of wasting the reject water by allowing it to flow to a drain, the reject water is returned to the water feed line downstream of the reverse osmosis system so that is can be used for other purposes. A section of the water feed line has a flow restrictor which estabishes a dynamic pressure drop. Feed water for the reverse osmosis system is taken off the feed line upstream of the restrictor and reject water is returned downstream of the restrictor, thereby reducing the water wastage due to the reverse osmosis process.
Patent•
11 Apr 1990
TL;DR: Semipermeable composite membranes which comprise a porous substrate of a homo- or copolymer on the basis of acrylonitrile are provided, which have been crosslinked, and at least two layers of film-forming polymers coated thereon, a first layer of monomeric or polymeric diazonium salts which have reacted with themselves and with an at least difunctional compound, and a second layer, which is chemically bonded to the first one, of a cross-linked, ionically charged hydrophilic polymer as mentioned in this paper.
Abstract: Semipermeable composite membranes which comprise a porous substrate of a homo- or copolymer on the basis of acrylonitrile are provided, which have been cross-linked, and at least two layers of film-forming polymers coated thereon, a first layer of monomeric or polymeric diazonium salts which have been reacted with themselves and with an at least difunctional compound, and a second layer, which is chemically bonded to the first one, of a cross-linked, ionically charged hydrophilic polymer. The membranes show good mechanical, physical and chemical stabilities, preferably solvent stability, and are useful in reverse osmosis and ultrafiltration processes, particularly for desalting solutions of low molecular weight organic compounds.
TL;DR: In this article, the compatibility of several commercially available RO membranes to chlorine dioxide, an oxidizer which compares favorably to chlorine in terms of bactericidal efficacy, was determined as a function of chlorine dioxide concentration, solution pH, and exposure time.
TL;DR: In this article, the authors compared the Fouling Index (FI) measurements of solutions containing inorganic or organic solutes with a flat channel test module measuring flux decline and salt rejection behavior with time.
TL;DR: In this paper, a model was proposed for predicting the permeate flux, permeate concentration, and brine concentration as a function of time in a reverse osmosis apparatus, when crystallization of calcium sulphate occurs.
Patent•
18 Apr 1990
TL;DR: A modified porous membrane can be prepared by dissolving an aromatic polymer having a thioether group in an organic solvent, forming membrane of the aromatic polymer from the resultant solution by phase conversion and oxidizing the formed membrane as mentioned in this paper.
Abstract: A modified porous membrane can be prepared by dissolving an aromatic polymer having a thioether group in an organic solvent, forming membrane of the aromatic polymer from the resultant solution by phase conversion and oxidizing the formed membrane. This modified porous membrane can effectively be utilized in a filtration method wherein ultrafiltration, reverse osmosis, fine filtration, gas separation, vapor permeation or pervaporation is conducted.
TL;DR: In this paper, a modified reverse osmosis membrane instead of lime softening is used to treat waters with low total dissolved solids, which is particularly cost effective in treating ground water in Florida which is high in hardness and natural organics such as humic and fulvic acids.
TL;DR: In this article, the authors showed that thin-film composite membranes can be used effectively for the separation of selected hazardous organic compounds, and that the overall ozonation-membrane process could be greatly effective in producing permeate water of high quality while minimizing the volume of waste that must be further treated.
Abstract: Extensive experimental studies showed that thin-film, composite membranes can be used effectively for the separation of selected hazardous organic compounds. This waste treatment technique offers definite advantages in terms of high solute separations at low pressures (<2 MPa) and broad pH operating range, and the use of charged membrane would allow the selective separation of some organics from feeds containing high salt concentrations. In addition, feed pre-ozonation of selected organics has been shown to provide significant improvement in flux and rejection characteristics for both charged and uncharged membranes due to formation of ionizable organic acid intermediates during the ozonation that do not interact as strongly with the membrane. It has been shown that the overall ozonation–membrane process could be greatly effective in producing permeate water of high quality while minimizing the volume of waste that must be further treated. Batch adsorption studies were also utilized to understand the membrane flux drop phenomena in non-ozonated solutions.
TL;DR: Application de la membrane Poly(1-trimethylsilyl-1-propyne) n-hexyldimethyl silyle, synthetisee par Sagami Chemical research center, a l'osmose inverse d'un melange ethanol/eau.
Abstract: Application de la membrane Poly(1-trimethylsilyl-1-propyne) n-hexyldimethylsilyle, synthetisee par Sagami Chemical research Center, a l'osmose inverse d'un melange ethanol/eau.
TL;DR: In this article, the effects of maturation time of casting solution and annealing conditions on reverse osmosis (RO) properties of nylon 4 membranes are studied, and the best results of 4.86 × 10−5 g/cm2 s of water flux with 74.2% of salt rejection for 1 wt % NaCl aqueous feed solution can be obtained in the conditions of plasma treatment for 80 W-3 min in a reactor with O2 on 25 wt% formic acid-4 h annesaling nylon 4 membrane.
Abstract: The effects of maturation time of casting solution and annealing conditions on reverse osmosis (RO) properties of nylon 4 membranes are studied. The effects of plasma treatment conditions, such as supply power, treatment time, and gases used in reactor, on the water contact angle, surface energy, water flux, and salt rejection of nylon 4 membranes are considered. The best results of 4.86 × 10−5 g/cm2 s of water flux with 74.2% of salt rejection for 1 wt % NaCl aqueous feed solution can be obtained in the conditions of plasma treatment for 80 W–3 min in a reactor with O2 on 25 wt % formic acid–4 h annealing nylon 4 membranes. The hydrophilic monomers, such as 1-vinyl-2-pyrrolidone (VP), 2-hydroxyethyl methacrylate (HEMA), and acrylic acid (AA), are plasma deposited onto the chemical and/or plasma etched nylon 4 membranes to improve the salt rejection without decrease in water flux. The salt rejection of 90.9% and water flux of 3.64 × 10−5 g/cm2 s of the deposited membrane are obtained in the conditions of depositing AA monomer onto the substrate membrane which was previously treated with annealing followed with plasma etching.
Patent•
07 Mar 1990
TL;DR: In this paper, the crosslinked polyamide separation layer of a reverse osmosis membrane was brought into contact with a miscible aq. soln. and was allowed to be held for a sufficient time.
Abstract: PURPOSE: To produce a membrane having a high flux, Ca and Mg removal rate and capable of operating at a lower pressure by bringing a crosslinked polyamide separation layer of a reverse osmosis membrane into contact with a miscible aq. soln. of strong mineral acid and holding this membrane at a raised temp. CONSTITUTION: In the membrane for removing ions, which give the hardness to water, the crosslinked polyamide of the reverse osmosis membrane is brought into contact with the miscible aq. soln. of strong mineral acid such as phosphoric acid, phosphorous acid and sulfuric acid. Then, the membrane in contact with this acid is held at the raised temp. and is allowed to be held for a sufficient time. Thereupon, the membrane having a >=326 l/m per day (8 gfd) flux and about >=65% magnesium sulfate removal rate is produced when tested in the reverse osmosis condition using an aqueous sol. of 0.2 wt.% magnesium sulfate at 345 pa (50 psi) and 25 deg.C. Further, this membrane is available at a low operating pressure.
TL;DR: In this article, a hollow fiber reverse osmosis system was used to separate ternary mixtures of sodium chloride and acetic acid aqueous solutions to investigate interactions between an inorganic salt and a weak organic acid which does not ionize extensively.
Patent•
29 Jun 1990TL;DR: In this paper, a method of treating an aqueous liquor, such as effluent liquor formed during coal gasification, is described, which comprises subjecting the liquor to dephenolation and ammonia stripping treatment to remove phenolic compounds and "free" ammonia from the liquor and then applying the resulting liquor, which still contains ammonium compounds and thus "fixed" ammonia, to reverse osmosis treatment to produce a permeate which is substantially free from impurities.
Abstract: The invention relates to a method of treating an aqueous liquor, such as effluent liquor formed during coal gasification. The method comprises subjecting the liquor to dephenolation and ammonia stripping treatment to remove phenolic compounds and "free" ammonia from the liquor and then subjecting the resulting liquor, which still contains ammonium compounds and thus "fixed" ammonia, to reverse osmosis treatment to produce a permeate which is substantially free from impurities, including "fixed" ammonia.
01 Jan 1990
TL;DR: The phenomena of colloidal and bacteriological fouling of RO spiral wound brackish water membranes is reviewed in this article. But, the need for extensive addition research is apparent.
Abstract: The phenomena of colloidal and bacteriological fouling of RO spiral wound brackish water membranes is reviewed. Generalizations from the literature about the mechanism of action of fouling are described. The monitoring methods used to measure colloidal and biofouling potential of feedwater is reviewed. The action of disinfectants and chemical cleaning agents on an established fouling layer is discussed. The need for extensive addition research is apparent.
TL;DR: In this article, the kinetics of the first phase of the concentration of skim milk were investigated, characterised by the deposition on the membrane of a layer which becomes rapidly compressed (1 to 2 min) into a membrane-like film forming a barrier against the permeation of water and dissolved substances.
TL;DR: In the reverse osmosis of a salt containing lactose solution compared with the permeation from a pure lactose solution under identical experimental conditions, it is thought that the displacement of uncharged molecules from the boundary layer in front of the membrane by charged ions, which accumulate at the membrane surface due to their strong forces of interaction, is the reason for the increased permeation rate of salt ions.
Journal Article•
01 Jul 1990-Journal of parenteral science and technology : a publication of the Parenteral Drug Association
TL;DR: The results of a nine-month study of a system designed to produce pharmaceutical grade water are provided, and CDI systems have been found to reduce the levels of total oxidizable carbon as well.
Abstract: Continuous deionization (CDI) devices to purify water have recently become available. CDI and reverse osmosis (RO) equipment can form the key elements of water treatment trains that produce ultrapure water, without the need for the chemical regenerants associated with batch ion-exchange processes. CDI systems used as downstream polishers of RO product water have been found to be effective for the removal of trace ionic contaminants. Recently, CDI technology was extended, and devices are now capable of removing dissolved carbon dioxide without the requirement of pH adjustment. Examples from a number of installations are provided. CDI systems have been found to reduce the levels of total oxidizable carbon as well. Field experiences are provided and discussed. RO/CDI systems can be maintained to provide product water with low levels of bacteria and pyrogens. The results of a nine-month study of a system designed to produce pharmaceutical grade water are provided.
TL;DR: In this article, the use of brine concentrators was proposed to reduce the reject brine to 2% of the overall flow and so significantly reduce the disposal problem in reverse osmosis plants.
TL;DR: In this article, a comparison technique et economique d'usines de dessalement utilisant de two techniques differentes de traitement (compression mecanique de vapeur and osmose inverse) and situees dans la region du Moyen Orient
TL;DR: In this paper, the effect of operating parameters (transmembrane pressure, flow rate, temperature and feed concentration) on the performance of a spiral-wound and a tubular thin-film composite reverse osmosis (RO) membrane during the concentration of milk was studied.