Showing papers on "Reverse osmosis published in 1974"

Water recycle treatment system for use in metal processing

Abstract: A water recycle treatment system comprising two main treatment sub-systems for treatment of contaminated water from a plurality of concentrated solutions and rinse baths to separate out the impurities therein. A first sub-system treats less concentrated solutions used for the rinse baths by channeling the flow therefrom to a first neutralizing tank which provides for pH control to produce a mixed output solution having a substantially constant pH factor, which is filtered to remove gross particles, the filtered solution being cooled in a holding tank and passed through a reverse osmosis process and carbon bed to produce clean water. The second sub-system treats highly concentrated solutions obtained from a plurality of chemical processes, mixes them in a second neutralizing tank which is utilized to produce a substantially constant pH output, which is fed to an evaporator to precipitate the metals and salts in sludge and also forms a water vapor output. The reverse osmosis waste is fed back into the second neutralizing tank and processed as noted above.

Cleaning of membrane surfaces

Abstract: In effecting the periodic cleaning of ultrafiltration and reverse osmosis type membrane separation units, the procedure is improved and shortened by utilizing a plurality of purgings, or flushings, that cause water droplets to be blown along in a high speed air stream such that there is a resulting removal of accumulated solids from a membrane surface. During purging, air is used until substantially all the water droplets are blown off the membrane surfaces but is not continued until the membrane starts to dry out.

Studies on reverse osmosis for concentration of fruit juices

Abstract: Data are presented for the osmotic pressures of commercially available lime, lemon, prune, carrot and salted and unsalted tomato juices and their concentrates. Similar data are presented for sucrose-water and glucose-sucrose (mole ratio 10:1)-water solutions in the temperature range 7.5–25°C. The effects of the temperature on parameters of process design show that by operation at a lower temperature it is possible to obtain a higher recovery of aroma compounds in the concentrate in the second stage reverse osmosis treatment of fruit juice water obtained from the first stage treatment. This possibility is confirmed by the experimental results at 7.5°C and 25°C.

Method of fabrication of hollow filament separatory module

Abstract: A method of making a module for use in processes such as reverse osmosis, ultrafiltration, dialysis, and the like in which hollow filaments to be utilized as semi-permeable membranes comprise a coreless annular array of helically wound filaments.

Method of manufacturing a semipermeable membrane from a water-soluble polymeric resin

Abstract: Ultrathin membranes for separating substances are obtained by exposing shaped articles comprising a water-soluble polymer or a mixture of a water-soluble polymer and water-insoluble polymer to a plasma of a gas selected from helium, argon, nitrogen, hydrogen, oxygen, carbon monoxide, carbon dioxide, ammonia, a hydrocarbon having 1 to 10 carbon atoms, an epoxide having 2 to 10 carbon atoms, or an alkylamine, or a mixture of these substances to crosslink the surface layer, and then washing the exposed articles with water to remove the unreacted portions. The membrane exhibits outstanding performance characteristics when used in the processes for separating or concentrating substances, such as reverse osmosis, ultrafiltration, and the like.

Polyimide membrane and process for making same

Abstract: The present invention relates to semipermeable asymmetric membranes and to a process for preparing them. These membranes are especially suitable for use in ultrafiltration and reverse osmosis.

Reverse osmosis separation of single and mixed alcohols in aqueous solutions using porous cellulose acetate membranes

Abstract: Reverse osmosis transport for alcohol-water systems in the Taft number (σ*) region of 0 to −0.3 is explored in detail. The numerical value of the polar functional constant for alcohols is 15.5 for the above σ* region in the operating pressure range of 50 to 500 psig for the cellulose acetate membrane material used. An analysis of the combined effect of operating pressure and mass transfer coefficient on the high-pressure side of the membrane shows that, under certain conditions, solute separation could pass through a maximum with increase in operating pressure. A general experession for solute separation is derived as a function of pore structure on membrane surface, polarity of solute, and operating conditions of the experiment. Alcohols behave independently in mixed solute systems. A method is described and illustrated for predicting alcohol separation in alcohol–sucrose–water feed solutions from data on single solute systems.

Reverse osmosis apparatus

Abstract: Reverse osmosis apparatus comprises a pressure shell, a feed solution inlet, a feed solution outlet, a product outlet, a membrane assembly within the pressure shell, and shell partition means for directing feed solution over parts of the assembly in a sequential manner.

Reducing lactose content in milk - by ultra-filtration and reverse osmosis, washing and mixing, and processing

Abstract: Diet milk having a modified lactose content is prepd. by (i) subjecting starting milk to ultra-filtration to recover a concentrate (I), consisting of milk pt. which does not pass through ultra-filter, and a permeate (II), consisting of milk pt. passing through ultra-filter; (ii) combining at least pt. of (I) and (II) having reduced lactose contents and (ii) subjecting prod. obtd. to at least one processing treatment. Lactose content in (II) may be reduced by reverse osmosis, to obtain a concentrate (III) contg. water, lactose, salts and low mol. wt. substances and a 2nd permeate (IV) consisting of water with a low salt content. Lactose content in (I) may be reduced by washing, esp. with deionised water or with (IV). Lactose content in (III) may be reduced by consecutive evaporation and crystallisation steps. Mixing conc. soln. from reverse osmosis with washed (I) may be preceded by enzyme-treatment of residual lactose with beta - galactoxydase and gal-l-P-uridyl transferase.

Mechanisms of brine-side mass transfer in a horizontal reverse osmosis tubular membrane

Abstract: The desalination performance of a tubular reverse osmosis membrane was studied under well-defined hydrodynamic conditions. Experimental measurements were made of local mass transfer rates in a 2.31-cm I.D. × 81-cm long horizontal cellulose acetate membrane at 16 locations along the tube length for both laminar and turbulent flows. The membrane's intrinsic permeability to water and NaCl was found to vary significantly along its productive length. The experiments suggest that the dominant transport mechanisms in laminar flow are forced convection in the upstream region and combined free and forced convection in the downstream region, beyond a distance of approximately 16 tube diameters, for all feed concentrations studied. The Deissler analogy applies well to the turbulent region for Re ≧ 104; however, it increasingly overpredicts performance as Re is decreased below 104. The experimental results of other workers are interpreted successfully in terms of the mechanisms deduced in the present work.

Novel polymer membranes for reverse osmosis

Abstract: This case is directed to the preparation of polyvinyl acetal resins as semi-permeable membranes for use in the treatment of feed solutions by reverse osmosis, ultafiltration or related techinques.

Experimental investigation of polarization effects in reverse osmosis

Abstract: With a Mach-Zehnder interferometer, salt concentration profiles were measured in a reverse osmosis system under natural convection with the membrane in a vertical position. The measured concentration profiles compared favorably with those predicted theoretically as long as the motion remained laminar. At large distances from the leading edge, however, the flow developed a wavy pattern, especially for bulk salt concentrations in excess of 0.1 moles/liter. As expected, whenever this motion became especially pronounced, the concentration of salt at the membrane surface was less and the production rate of fresh water greater than that predicted using the laminar analysis.

Reverse osmosis system with automatic flushing

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.

The Fractionation of Glucose Syrups by Reverse Osmosis

Abstract: Glucose syrups, which are clear, aqueous solutions of malto-oligosaccharides and maltodextrins, are ideal materials for processing by reverse osmosis or ultrafiltration techniques. Hence membrane filtration methods, in their widest sense, can be used to achieve molecular separation of glucose syrup components without any particular technological difficulty. This paper presents details of the pilot-scale fractionation of 43% D. E. acid-converted glucose syrup by passage through ‘loose’ and ‘tight’ cellulose acetate membranes, and changes of D. E. and sugar spectrum likely to be achieved on the basis of current knowledge. The very low protein concentrations encountered in commercial glucose syrups minimise difficulties of concentration polarisation which arise in many other applications. Viscosity problems do not arise below 30% w/v operating concentrations and the fractionation of glucose syrup by reverse osmosis appears to be more straightforward than its concentration by the same technique. Fractionation of glucose syrup by reverse osmosis offers a means for the manufacture of several new types of syrup, and enables entire groups of sugars to be eliminated under selected conditions. Products in the range 43–80% D. E. or 15–43% D.E. can be obtained using suitable combinations of different membranes, and the latter type by a single membrane filtration. Thus reverse osmosis may take its place as a unit operation of glucose syrup manufacture in the future.

Feed water chlorinator for a reverse osmosis system

Abstract: A feed water chlorinator for a semipermeable membrane separation system employs a bactericide consisting essentially of a mixture of an organic fatty acid compound and a chlorisocyanuric acid compound compacted into a tube, as a container, open at least at one end. The bactericide-containing tube is located in the feed water piping so that the feed water flows over its open end or ends, and may be arranged as a side arm in the feed water inlet pipe, or located inside a filter in the feed water inlet pipe.

Process for treating waste water containing radioactive substances

Abstract: A process for treating waste water containing radioactive substances comprising treating the waste water by reverse osmosis in the presence of at least one organic surfactant selected from the group consisting of anionic surfactants, cationic surfactants and nonionic surfactants.

Apparatus for control of a reverse osmosis system

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.

Means for increasing the flow across a reverse osmosis membrane using an alternating electric field

Abstract: Method for removing a solute from solution, particularly for water desaliion, which involves contacting a semi-permeable membrane with the solution, and impressing an alternating electric field on the contacting surface, the field having a frequency corresponding to the relaxation frequency of the solute.

Boric acid process

Abstract: Boric acid is recovered from impure mother liquors from boric acid processes by use of porous membranes, such as cellulose acetate, by a reverse osmosis technique.

Method and installation for the treatment of waste water to form useful water

Abstract: A method for the treatment of waste water to form useful water, comprising the steps of subjecting the waste water to a chemical flocculation treatment, floating the formed turbid portion of the waste water, and subjecting the clarified water to reverse osmosis filtration. The waste water treatment plant or installation for the performance of the aforesaid method comprises, in combination, apparatus for carrying out the chemical flocculation treatment, an electro flotation installation, and a reverse osmosis installation.

Method for casting and handling ultra-thin reverse osmosis membranes

Abstract: A method of casting ultra-thin semipermeable membranes comprises the steps of: (A) applying a coating of a film forming water soluble solution, containing a leachable pore producing agent and a polymer which is not substantially degraded by organic polar solvents, onto a smooth casting surface, (B) drying the coating to form a support film about 0.5-10 mils thick, (C) applying a coating of an organic polymeric membrane coating solution onto the support film, and drying the coating to form a semipermeable reverse osmosis membrane film about 0.01-1.0 mil thick and (D) applying a leaching liquid to the films, to cause pore formation in the support film and to form a composite consisting of a 0.01-1.0 mil thick semipermeable membrane, supported by a 0.5-10 mils thick water soluble film support of between about 5-50% porosity.

Polar and steric effects in reverse osmosis

Abstract: The effects of polar parameter Σσ* and steric parameter ΣEs on reverse osmosis separations of alcohols, aldehydes, ketones, and ethers (noncyclic) in aqueous solutions involving single solute systems and porous cellulose acetate membranes are discussed. The least-squares and multiple-regression analyses of solute transport parameter data show that the separation of aldehydes, just as that of alcohols, is predominantly a function of Σσ*, and that of ethers is predominantly a function of ΣEs, whereas that of ketones is best represented as a function of both Σσ* and ΣEs. The results also indicate that even where water is preferentially sorbed at the membrane solution interface, solute separation in reverse osmosis is affected by the nonpolar character of the solute molecule. A general expression for solute transport parameter in reverse osmosis is presented for further study.