Showing papers on "Reverse osmosis published in 1979"
Patent•
22 Feb 1979
TL;DR: Good salt rejection and flux characteristics can be obtained with reverse osmosis membranes made from crosslinked, interfacially polymerized aromatic polyamides, particularly poly(arylenepolyamine aromatic polycarboxylamides) such as poly(phenylenediamine trimesamide) as discussed by the authors.
Abstract: Good salt rejection and flux characteristics can be obtained with reverse osmosis membranes made from crosslinked, interfacially polymerized aromatic polyamides, particularly poly(arylenepolyamine aromaticpolycarboxylamides) such as poly(phenylenediamine trimesamide). The aromatic polyamides are preferably synthesized directly from an essentially monomeric polyacyl halide (at least tri- or higher in acyl functionality) and an essentially monomeric arylene polyamine with a measurable water solubility. As compared to closely analogous linear polymers, these interfacially polymerized, crosslinked polyamides have a lower % elongation and lower solubility (e.g. in amide solvents). Chlorine resistance characteristics of these polyamides are also good and can be improved by treatment with a chlorinating agent. In the preferred practice of the method for making a reverse osmosis membrane, a porous support layer is coated with the polyamine component (e.g. an aqueous solution of phenylene diamine); the thus-coated support is contacted with the polyacyl halide component (e.g. trimesoyl chloride), thereby initiating the interfacial polymerization in situ on the support; and the resulting product is dried to provide a composite membrane comprising the polyamide laminated to the porous support.
537 citations
Patent•
10 Jan 1979
TL;DR: A composite permselective membrane as discussed by the authors is prepared by reaction of a film or layer containing cycloaliphatic polyfunctional secondary amines with a triacyl halide or its mixture with a diacyl ion.
Abstract: A composite permselective membrane is prepared by reaction of a film or layer containing cycloaliphatic polyfunctional secondary amines with a triacyl halide or its mixture with a diacyl halide. The membrane is useful in separating components of fluid mixtures or solutions, such as the removal of salts from aqueous solutions by reverse osmosis.
275 citations
Patent•
05 Sep 1979TL;DR: In this paper, a semipermeable composite membrane for desalination of saline or brackish water by reverse osmosis was proposed. But it was not shown to be suitable for use in the real world, since it required a polyfunctional compound containing at least two functional groups capable of reacting with the amino group.
Abstract: A semipermeable composite membrane comprising a thin semipermeable film of a polymeric material deposited on one side of a microporous substrate, said polymeric material being prepared by crosslinking a soluble polymer containing at least 30 mole % of a recurring unit of the formula ##STR1## wherein all symbols are as defined in claim 1, and having at least 0.2 milliequivalent, per gram of said polymer, of an amino group containing 1 or 2 active hydrogen atoms, with a polyfunctional compound containing at least two functional groups capable of reacting with the amino group having 1 or 2 active hydrogen atoms; and a process for preparing the same. The semipermeable composite membrane of this invention is especially useful for desalination of saline or brackish water by reverse osmosis.
97 citations
TL;DR: Differential scanning calorimetry (DSC) has been used in the study of a series of hydrogels in an attempt to correlate water binding and transport properties as mentioned in this paper.
Abstract: Differential scanning calorimetry (DSC) has been used in the study of a series of hydrogels in an attempt to correlate water binding and transport properties. DSC and oxygen transport studies were carried out on a series of styrene-2-hydroxyethyl methacrylate copoly-mers. The transport of dissolved oxygen through those copolymers that contained no freezing water was found to be negligible in comparison to those in which both freezing and non-freezing water was present. This correlates well with the observation that the dense layer of asymmetric cellulose acetate reverse osmosis membranes was found to contain little or no free water.
On this basis, the use of DSC in the design of a hydrogel that contains little or no freezing water (to promote salt rejection) with a reasonably high total water content (to maximise water flux) for use in reverse osmosis, is described. The resultant copolymer of acrylamide, methacrylic acid and styrene has a total equilibrium water content (30 per cent) that is twice that of a typical dense cellulose acetate used in reverse osmosis and a very low (< 1 per cent) freezing water content.
Examination of the fine structure of the melting endotherms and freezing exotherms associated with various hydrogels shows several interesting features which are interpreted in terms of the existence of a continuum of water states. These range from water that is unaffected by its polymeric environment to water (on average two or less molecules per monomer repeat unit) that is hydrogen bonded to functional groups in the polymer.
86 citations
TL;DR: In this paper, a study has been made of the major components present in secondary sewage effluents to determine their relative importance when considering the rate of membrane fouling and the pH of the system has also been shown to be critical with the lowest rates of fouling occurring at a product water pH of 5.0 corresponding to a pH in the feed solution of 6.0.
54 citations
Patent•
05 Dec 1979
TL;DR: In this paper, a combined reverse osmosis electrodialysis assembly with anionic-cationic bilaminate ion exchange composition and electrodes supplying electrical current which effects water splitting at the membrane faces to produce acidity in osmotic feed stream.
Abstract: The disclosed apparatus is a combined reverse osmosis electrodialysis assembly having osmotic membranes of anionic-cationic bilaminate ion-exchange composition and having electrodes supplying electrical current which effects water-splitting at the membrane faces to produce acidity in osmotic feed stream to prevent salt precipitation. Periodic current reversal inhibits membrane pore plugging and fouling. Heat sealing of membranes and spiral wound array are useful design variants.
31 citations
TL;DR: In this paper, it was found that reductions in the pH of solutions surrounding the membrane when not pressurised are effective in loosening the fouling, and physico-chemical studies were described which are able to produce an explanation of the mode of action of the pH effect.
29 citations
Patent•
20 Aug 1979TL;DR: In this paper, the authors describe a process for the control of bacterial growth in polyamide reverse osmosis membranes by treatment with iodide, hydrogen peroxide, or hydrogen peroxides derivatives.
Abstract: Process for the control of bacterial growth in polyamide reverse osmosis membranes by treatment with iodide, hydrogen peroxide, or hydrogen peroxide derivatives.
27 citations
TL;DR: Water factory 21 is a 0.66mVs (15mgd) advanced wastewater treatment plant operated by the Orange County (Calif.) Water District as mentioned in this paper, which is designed to improve the quality of biologically treated municipal wastewater for injection into groundwater, thereby preventing seawater intrusion.
Abstract: Water factory 21 is a 0.66-mVs (15mgd) advanced wastewater treatment plant operated by the Orange County (Calif.) Water District. It is designed to improve the quality of biologically treated municipal wastewater for injection into groundwater, thereby preventing seawater intrusion. The processes and concerns of this facility are similar to those of facilities treating highly contaminated water supplies for potable purposes. The processes implemented at the water factory are lime treatment, air stripping, recarbonation, chlorination for algae control, filtration, granular activated carbon adsorption (GAC), reverse osmosis, and final chlorination for disinfection and ammonia removal.
23 citations
TL;DR: Microfouling in desalination is a process in which the rate of increase of the mass of surface film is dependent in large part on the specific character of the environment, most particularly the physical, chemical and biological condition of the intake sea water.
22 citations
TL;DR: In this paper, the reverse osmosis separations of polyethylene glycol (PEG) solutes in the average molecular weight range of 200 to 6750 in single-solute dilute aqueous solutions have been studied using porous cellulose acetate membranes at the operating pressures of 50, 75, and 100 psig.
Abstract: Reverse osmosis separations of eight polyethylene glycol (PEG) solutes in the average molecular weight range of 200 to 6750 in single-solute dilute aqueous solutions have been studied using porous cellulose acetate membranes at the operating pressures of 50, 75, and 100 psig. Diffusivity data for the above PEG solutes have also been obtained from experimental data on intrinsic viscosities. From an analysis of all experimental data, numerical values for the parameters representing the polar (−ΔΔG/RT), steric (δ*ΣEs), and nonpolar (ω*Σs*) forces governing reverse osmosis separations of PEG solutes have been generated. These numerical values are useful for precise characterization of cellulose acetate membranes for whose specifications sodium chloride is not the appropriate reference solute because of its low or practically negligible separation under reverse osmosis operating conditions. This work also illustrates that solute separation in reverse osmosis can predictably increase or decrease with increase in operating pressure depending on experimental conditions.
Patent•
22 Jan 1979
TL;DR: In this paper, the U-shaped sealing rings are used for desalination and purification of water by reverse osmosis and ultra-filtration, which are made of synthetic material having a limited flexibility.
Abstract: An apparatus for desalination and purification of water by reverse osmosis and ultrafiltration. Such apparatus require seals at the individual modular elements between the untreated water passages and the permeate-withdrawal passages. These seals comprise two sealing rings which are essentially U-shaped, are of similar but inverted shape, and are made of synthetic material having a limited flexibility. Pairs of the sealing rings sealingly abut one another in the central plane of the modular guide plate via respective ones of their arms which extend essentially radially. The second, outward disposed arms sealingly contact an adjacent diaphragm. Disposed on the outer surface of the portion which connects the arms are channels for the withdrawal of the permeate.
Patent•
16 May 1979TL;DR: In this paper, a semipermeable composite membrane was proposed for desalination of saline or brackish water by reverse osmosis. But it was not shown to be suitable for desalinization of seawater.
Abstract: A semipermeable composite membrane comprising a thin semipermeable film of a polymeric material deposited on one side of the microporous substrate, said polymeric material being prepared by interfacial crosslinking of a polymer containing a recurring unit of the formula ##STR1## wherein each of R 1 and R 2 represents a hydrogen atom or a methyl group, and W 1 represents a direct bonding or a sulfonyl group (--SO 2 --), with a polyfunctional compound containing at least two functional groups selected from acid halide, sulfonyl halide, isocyanate, N-haloformyl, haloformate and acid anhydride groups; and a process for producing the same The semipermeable composite membrane of this invention is especially useful for desalination of saline or brackish water by reverse osmosis
TL;DR: The world's largest reverse osmosis system for seawater desalination was placed on-line in January 1979 to supply 12,000 cubic meters of desalted Red Sea water per day to the drinking water supplies of Jeddah, Saudi Arabia as mentioned in this paper.
TL;DR: In this paper, the authors extended the theory of reverse osmosis in bilayer membranes and showed that at high fluxes the selectivity of the layer on the high pressure side dominates the salt rejection also in case this layer has the lowest selectivity.
TL;DR: In this paper, the authors presented a second update of costs, originally presented in ORNL/TM-5070, which gave cost estimates for desalting seawater and brackish water based upon first quarter 1975 costs.
Patent•
24 May 1979
TL;DR: In this paper, two ion selective semipermeable membranes are joined to one another at their edges so as to form a pouch with ion permeable walls, and the membranes are provided with end flow ports into the pouch region.
Abstract: Two ion selective semipermeable membranes, such as are used in electrodialysis cell assemblies, are joined to one another at their edges so as to form a pouch with ion permeable walls. The membranes are provided with end flow ports into the pouch region. The pouch is wound into a spiral so as to resemble a spiral wound reverse osmosis module. A central hub electrode and a peripheral cylindrical electrode are provided. With suitable electrolyte streams the system operates as an electrodialysis cell assembly.
Patent•
27 Jul 1979
TL;DR: In this paper, a bridged polymer of furfuryl alcohol is formed on the surface of a porous supporting membrane consisting of polysulfone, followed by polymerization by heating, and the composite membrane thus obtained is used as a barrier layer.
Abstract: PURPOSE:To maintain the separating capacity of the semipermeable composite membrane for a long period of time by adding a sulfite, a bisulfite, or solfurous acid gas and a manometric agent for ions of heavy metal to a treating liquid in the separation and recovery of inclusions from liquid by a reverse osmosis method using the specific semipermeable composite membrane. CONSTITUTION:In the manufacture of pure water by recovering valuables present in industrial water, sea water, etc., the semipermeable thin membrane consisting of a bridged polymer of furfuryl alcohol is formed on the surface of a porous supporting membrane consisting of polysulfone by coating it with an aqueous solution containing furfuryl alcohol and an acid catalyst, e.g., sulfuric acid, followed by polymerization by heating, and the composite membrane thus obtained is used as a barrier layer. In this case, to the treating liquid 5-100ppm of a sulfite, a bisulfite, or sulfurous acid gas and 20-500ppm of the heavy matalian manometric agent, e.g., ethylenediamine tetraacetic acid, etc., are added. Thus, the separating capacity of the said composite membrane can be maintained for a long period of time.
TL;DR: The general applicability of ultrafiltration and reverse osmosis in the dairy industry is reviewed and consideration is given to the problems of hygienic design and operation of membrane systems, particularly from the point of view of cleanability and sanitation.
TL;DR: In this article, reverse osmosis membranes prepared by plasma polymerization of allylamine-nitrogen mixtures over a porous substrate were evaluated for the rejection of components present in washwater.
Abstract: Reverse osmosis membranes prepared by plasma polymerization of allylamine–nitrogen mixtures over a porous substrate were evaluated for the rejection of components present in washwater. The membranes exhibited high rejections for sodium chloride, potassium chloride, detergent, and dextrose. High rejections of urea could be achieved, but only at a sacrifice of water flux. Lactic acid could also be rejected but caused a degradation of the plasma-deposited layer.
Patent•
05 Sep 1979
TL;DR: In this article, a semipermeable composite membrane was proposed for desalination of saline or brackish water by reverse osmosis, which has good selective permeability characteristics and good chemical resistance and thermal stability.
Abstract: A semipermeable composite membrane comprising a thin semipermeable film of a polymeric material deposited on one side of a microporous substrate, said polymeric material being prepared by crosslinking a soluble polymer containing at least 30 mole % of a recurring unit of the formula
wherein all symbols are as defined in claim 1 and having at least 0.2 milliequivalent, per gram of said polymer, of an amino group containing 1 to 2 active hydrogen atoms, with a polyfunctional compound containing at least two functional groups capable of reacting with the amino group having or 2 active hydrogen atoms; and a process for preparing the same The semipermeable composite membrane of this invention is especially useful for desalination of saline or brackish water by reverse osmosis. The membrane has good selective permeability characteristics and good chemical resistance and thermal stability.
TL;DR: In this paper, a review of the effects of certain physico-chemical properties of skim milk and wheys on the process performance is presented, including composition and molal concentrations of protein, lactose, and salt fractions related to experimental, calculated, or handbook data for osmotic pressure, viscosity and diffusivity of dairy fluids.
Patent•
05 Mar 1979
TL;DR: In this article, a purification process for waste water from a textile plant and other manufacturing processes is described, where the waste water is treated with a reducing agent, if needed, and the pH adjusted to 8.0-9.5.
Abstract: A purification process for waste water from a textile plant and other manufacturing processes. After preliminary filtering to remove foreign particles, the waste water is treated with a reducing agent, if needed, and the pH adjusted to 8.0-9.5. The waste water is then treated with a flocculating agent. After further treatment in a clarifier, the waste water is passed through a sand filter to remove any residual suspended solids. The pH is adjusted to below about 6.0 and the waste water is then subjected to reverse osmosis.
Patent•
09 Feb 1979
TL;DR: In this paper, a porous structure of fluorine plastic is impregnated with a water-soluble high polymer solution in inner pore spaces and cured to form said porous structure used as membrane for filtration, dialysis, ultrafiltration, and reverse osmosis.
Abstract: PURPOSE:A porous structure of fluorine plastic is impregnated with a water-soluble high polymer solution in inner pore spaces and the water-soluble high polymer is cured to form said porous structure used as membrane for filtration, dialysis, ultrafiltration, and reverse osmosis because of its uniform hydrophilic property and high mechanical strength.
Patent•
16 Oct 1979TL;DR: In this paper, a semipereable composite membrane comprising a thin semipermeable film of a polymeric material deposited on one side of a microphorous substrate is described.
Abstract: A semipereable composite membrane comprising a thin semipermeable film of a polymeric material deposited on one side of a microphorous substrate, said polymeric material being prepared by crosslinking a soluble polymer containing at least 30 mole% of a recurring unit of the formula wherein all symbols are as defined in Claim 1, and having at least 0,5 milliequivalent, per gram of said polymer, of an amino group containing 1 or 2 active hydrogen atoms, e.g. the unit of the formula with a polyfunctional compound containing at least two functional groups capable of reacting with the amino group having 1 or 2 active hydrogen atoms, e.g. isophthaloyl chloride and a process for preparing the same. The semipermeable composite membrane of this invention has selectivity, flexibility, resistance and storability and is especially useful for desalination of saline or brackish water by reverse osmosis.
TL;DR: In this paper, the authors used high energy electrons to improve properties of cellulose acetate membranes for reverse osmosis desalination, and the grafting parameters (radiation dose and method, monomer concentration, solvents, chain transfer agent and redox system) were considered.
TL;DR: In this article, the water flux and salt rejection properties in reverse osmosis of cellulose acetate-g-acrylamide membranes are determined using computerized programs, using 0.1 and 1.0 M sodium chloride, sodium sulphate and ammonium sulphate solutions.
Patent•
29 Jun 1979TL;DR: In this paper, the relative concentrations of solvent and solute in a solution are altered by a system which includes a cell having chambers separated by a membrane and a means for creating a pressure differential across the membrane.
Abstract: The relative concentrations of solvent and solute in a solution are altered by a system which includes a cell having chambers separated by a membrane and a means for creating a pressure differential across the membrane A solution moves through an inlet means around the system and countercurrent and reflux flow and outlet means The cell may be formed of modular units in such a way as to effect a tapered configuration so that the flow rate is homogeneous around the system
TL;DR: In this article, the impact of recently enacted legislation on the OWRT program and newly obtained results of operational testing with reverse osmosis composite membranes for both seawater and low pressure brackish water desalting applications are described.