Showing papers on "Desalination published in 1971"

Waste water treatment by solvent extraction

Abstract: A review is presented of the application of solvent extraction to the treatment of waste waters. Methods of extraction, solute-solvent separation and water — solvent separation are described. Phenol removal, oily water treatment, desalination, metal recovery by “liquid ion exchange” and miscellaneous other applications are described/ Available economic data are discussed. Possible future applications are outlined and it is suggested that greatest potential is in the treatment of oily waste water and of relatively concentrated streams containing valuable or noxious materials

Transport in Composite Reverse Osmosis Membranes

Abstract: Reverse osmosis desalination membranes have been prepared by laminating a very thin film of a semipermeable material to a finely porous support membrane. Film thicknesses are typically 1000 A. Structurally, these membranes are similar to the asymmetric cellulose acetate membranes first made by Loeb and Sourirajan. The composite membranes offer a choice of materials from which to prepare the desalination film and the porous support. Composites made by this procedure exhibit stable single-pass desalination of seawater with typical water fluxes of 5 × 10−4 g/cm2-sec (10 gal/ ft2-day). The water flux through the composite with a given difference in water activity depends on the water permeability and the thickness of the thin film and the characteristics of the pores in the surface of the support. Water permeabilities have been measured in direct osmosis. When the distance between pores is large compared with the thickness of the thin film, significant reduction in flux can occur. The relationship between film thickness, the porosity and pore size of the support, and this flux reduction has been calculated, and the calculations compare favorably with observations made on composite membranes.

Diffusion and reverse osmosis through polymer membranes

Abstract: The results obtained in this osmosis experiments compare very well with those obtained in laboratory-sized reverse osmosis units.

Method of preparing an asymmetric membrane from a cellulose derivative

Abstract: ASYMMETRIC MEMBRANES ARE PREPARED FROM NON-SELECTIVE THERMALLY GELLED SUBSTRATES OF A CELLULOSE DERIVATIVE. AFTER LEACHING, THE SUBSTRATE IS ANNEALED AND THEN TREATED IN A DILUTE AQUEOUS SOLUTION OF EITHER P-DIOXANE, FORMIC ACIDS OR NITROMETHANE AT AN ELEVATED TEMPERATURE. THE RESULTING SEMIPERMEABLE MEMBRANE IS PARTICULARLY SUITED FOR DESALINATION BY REVERSE OSMOSIS.

Extracting water from the atmosphere

Abstract: Water is extracted from the atmosphere by circulating a large volume of a solution of lithium chloride in water continuously over a Munters packing in a tower of conventional cooling tower design Excess solution formed as a result of the absorbtion of water is bled off and passed through a desalination plant where product water is produced Concentrated brine is returned to the circulating volume

Hardening of distilled water

Abstract: Hardening of distilled water, partic. the distillate from desalination of sea water or brackish water, is effected by gasifying the distillate with CO2 produced by acidifying raw water and subsequently neutralising the CO2-contng. water with calcium and/or magnesium compounds, pref. to the stage where all aggressive CO2 is removed.

Preparation and properties of poly(acrylic acid) composite membranes

Abstract: A new type of membrane has been prepared for hyperfiltration (reverse osmosis) desalination that is essentially a very thin polyelectrolyte membrane. It is prepared by casting an aqueous solution of a polyelectrolyte, specifically poly(acrylic acid) (PAA), directly on one surface of a finely porous support membrane. In hyperfiltration tests, these composite membranes exhibit desalination performance comparable in dilute solutions to that observed with cellulose acetate membranes of the Loeb-Sourirajan type. The water flux through these membranes is linear in the pressure up to 100 atm. Salt rejection is a function of pressure; it is also a function of the concentration of the feed solution and the charge of the counterion, in qualitative agreement with the Donnan ion-exclusion mechanism. Typical long-term results range from water fluxes of 2 × 10−3 g/cm2-sec (50 gal/ft2-day) and 80% salt rejection to 0.2 × 10−3 g/cm2-sec (5 gal/ft2-day) and >99.5% salt rejection at 1500 psi with 0.3 wt-% NaCl. These membranes appear to be useful for brackish water desalination.

Model Studies of Outfall Systems for Desalination Plants. Part 1. Flume Study of the Mixing Characteristics of Dense Jets Discharged into a Flowing Fluid. Volume 1. Main Text. Appendix A: Notation. Appendix B. Conductivity Probe Calibration and Data Reduction

Abstract: : In the planning and design of plants for desalination of salt water, a major consideration is the environmentally acceptable disposal of the waste brine--a warm, dense, highly salt-laden effluent whose concentrations of copper and other metallic ions are considered to be a threat to the marine ecology. Among the several alternatives for disposal of this brine is the economically attractive one of discharging the effluent back into the ocean or estuary from which it was withdrawn. However, a means of mixing the dense liquid with the ambient fluid sufficiently to dilute the concentration of various salts to safe levels is required. The report discusses, procedures for dilution, tests and recommendations.

Desalination of water

Abstract: 1,241,174 Evaporators, flash type; desalination of water BRITISH OXYGEN CO, Ltd 4 Nov, 1968 [3 Nov, 1967], No 50118/ 67 Heading BIB Fresh water is obtained by passing salt water from pump 31 through a heat-exchange coil 22 wherein it is heated by hot compressed ammonia vapour (or sulphur dioxide or a fluorinated hydrocarbon) flowing through heat exchanger 19, and then passing the heated salt water through line 32 into chamber 11 where it flows down over trays 15 and undergoes partial vaporization; the vapours condense on heat-exchange coil 12 and the distillate (fresh water), collected in tray 13, is withdrawn through line 40 The liquified ammonia leaving heat exchanger 19 flows through expansion valve 16 into heat-exchange coil 12, and then enters reservoir 17 Ammonia vapour is withdrawn from reservoir 17 by compressor 18, and is recycled to heat exchanger 19 Some of the brine withdrawn from chamber 11 through line 35 is discharged from the system through line 36, but a major proportion is recirculated to coil 22 Make-up salt water is supplied by line 29 This make-up water may be used to provide additional cooling for heat-exchange coil 12 The mechanical compressor 18 may be replaced by a thermal compressor operating on the vapour-adsorption principle The vaporization of water may be carried out under subatmospheric pressure maintained by a pump operated by the compressed ammonia or other working fluid The heat exchanger may be made of copper

Sea-water desalination

Abstract: In a special chamber sea water is vaporized by solar energy under continuous air saturation, being subsequently condensed as frest water. The chamber has a tub for the sea-water and multi-cap shaped cover with air supply branches. The cap section bases are so immersed in the sea-water as to form individual air-tight chambers.

Development of Polyphenylene Oxide Membranes

Abstract: Report concerning manufacturing variables on sulfonated polyphenylene oxide reverse osmosis membranes. The effects these variables have membrane performance are discussed as well as procedures to increase membrane reproducibility and performance.

Membranes for Pressure Permeation

Abstract: Molecular separations of gases by passage through a thin, dense membrane have been known for at least 140 years.(1) Even the desalination of water by passing it through a membrane under pressure with the exclusion of dissolved salts was known and named reverse osmosis 45 years ago.(2) Yet it was not until the 1960’s that the latter became an important, practical process. For one thing, identification of water supply as a vital problem requiring public support for alternative sources was necessary. Following this awareness came seven-digit investment in laboratory research by public agencies such as the State of California and the U. S. Department of Interior which led among other advances to the asymmetric membrane.(3,3a) This development cut the area of membrane surface required and hence the cost of an installation for a given volume processed to one-hundredth of that previously thought necessary. With the arrival of submicron,thin membranes a new unit operation was born.(4,5,6,7)

Method for demineralization by electrodialysis and apparatus therefor

Abstract: 1,224,070 Electro-dialysis SUMITOMO ELECTRIC INDUSTRIES Ltd Dec17, 1968, No59855/68 Heading C7B An electro-dialysis cell for demineralizing water is divided into a plurality of alternate desalination and concentration chambers 3 and 4 by alternately placed cation-exchange and neutral membranes 1 and 2, the end electrode chambers 5 and 6 being in contact with cathode 7 and anode 8 respectively The liquid to be demineralized, eg sea water, is fed through channel 9, drinking water being extracted from channel 10 In operation, potential gradients higher than 10 volt/cm are applied in the desalination chamber A porous neutral membrane may be prepared by dissolving PVC and tricresylphosphate into tetrahydrofuran, applying the resultant solution on polypropylene cloth, and after drying extracting the tricresylphosphate with methanol

Multistage Flash Desalination Utillizing Diesel Generator Waste Heat

Abstract: : A multistage flash evaporator utilizing diesel generator waste heat has been developed for desalination. After preliminary experimental studies, a unit was constructed to operate continuously from a variable heat supply and produce between 2,500 and 6,000 gpd of freshwater. Interstage brine transfer is automatically regulated by level controllers in each stage, thus eliminating the need for manual control of the unit as the generator load and hence heat output varies. All-aluminum construction has reduced corrosion, and the unit has performed satisfactorily during tests. Typical experimental data is included.