Showing papers on "Reverse osmosis published in 1983"

Microbial fouling of reverse-osmosis membranes used in advanced wastewater treatment technology: chemical, bacteriological, and ultrastructural analyses.

Abstract: Biofouling of reverse-osmosis membranes was investigated at an advanced wastewater treatment facility. Cellulose diacetate membranes operated for approximately 4,000 h became uniformly coated with a mucilaginous fouling layer. The fouling material was approximately 93% water by weight, and nearly 90% of the dehydrated residue was organic in composition. Calcium, phosphorous, sulfur, and chlorine were the major inorganic constituents detected. Protein and carbohydrate represented as much as 30 and 17%, respectively, of the dry weight of the biofilm. Bacteriological plate counts indicated up to 5.6 X 10(6) CFU/cm2 of membrane surface. Accumulation of [3H]glucose in the biofilm and measurement of ATP indicated that the fouling bacteria were metabolically active in situ. The genus Acinetobacter and the Flavobacterium-Moraxella group were the major generic groups associated with the feedwater surface of the membrane, whereas species of the generic groups Acinetobacter, Pseudomonas-Alcaligenes, and Bacillus-Lactobacillus predominated on the permeate water surface. Electron microscopy revealed that the biofilm on the feedwater surface of the membrane was 10 to 20 microns thick and was composed of several layers of compacted bacterial cells, many of which were partially or completely autolyzed. The bacteria were firmly attached to the membrane surface by an extensive network of extracellular polymeric fibrils. Polyester (Texlon) support fibers located on the permeate surface of the reverse osmosis membranes were sparsely colonized, suggesting bacterial regrowth in the product water collection system.

Continuous process for the reclamation of waste drilling fluids

Abstract: A continuous process for the reclamation of a slurry of waste drilling mud fluids and water normally resulting from drilling operations. The process comprises the steps of conducting the drilling mud slurry to a slurry surge tank for liquid solid separation by chemical and physical methods. The mud slurry is subjected to a primary solids separation unit after pH adjustment is used to initiate coagulation and an organic flocculant is added to aid flocculation of the solids. The water is then subjected to a secondary solids removal, and the solids recovered are reintroduced in the primary solids separation unit. Thereafter the water obtained from the secondary solids removal is then subjected to a chemical oxygen demand reduction unit having a carbon adsorption unit or reverse osmosis membrane units therein to remove organic matter or dissolved solids to produce water meeting environmental discharge requirements. The solids removed from the primary solids separation unit are converted to a cake meeting leachate requirements for other beneficial use.

Method for solvent recovery in solvent separation of ethanol from water

Abstract: A process for the separation of ethanol from water using solvent extraction at elevated pressures is disclosed. Separation is effected by contacting aqueous ethanol with either propylene (propene), allene (propadiene), methyl acetylene (propyne), or methyl allene (1,2-butadiene). This produces two liquid layers which separate because of the difference in their densities, and are easily drawn off as separate streams. The solvent is recovered by reverse osmosis means in a liquid state. The ethanol and water remain in a liquid state and are substantially recovered.

Preconcentration of Apple Juice by Reverse Osmosis

Abstract: Single strength apple juices (10° Brix) were processed by reverse osmosis to 20-25°Brix, primarily at 20°C. A pilot scale plate and frame UF-RO system equipped with cellulose acetate (CA) membranes, CA-865 and/or CA-990, or high resistance (HR) membranes, HR-95 and/or HR-98, was operated at pressures of 35-45 bar. At 45 bar, the larger pore-sized CA-865 possessed the highest processing capacity of 26.9 L/m2/hr (from 10°Brix to 20°Brix) and concentration limits of 35° Brix, but had low recovery of solutes and flavor volatiles. The HR-95 and HR-98 had similar processing capacities of 15-16 L/m2/hr and concentration limits of 20-25° Brix at 45 bar. The recoveries of 97% solutes and 87% apple flavor volatiles were obtained using either the HR-95 or the HR-98.

Method and apparatus for purifying and dispensing water

Abstract: An apparatus and method for purifying and dispensing water for use in a coin operated vending machine is disclosed. The apparatus includes a pair of filters where the preliminary filtering of raw water occurs, a reverse osmosis unit pump and a reverse osmosis unit where the main purification takes place. The permeate output of the reverse osmosis unit passes through a conductivity sensor. If the conductivity is below a predetermined level, the water is sent to a storage tank. If the water is above that level then it is sent back to the reverse osmosis unit pump for further processing by the reverse osmosis unit. Water is extracted from the storage tank by a continuously operating pump which transmits the water through an ultraviolet sterilizer. During a vend cycle the water passing through the ultraviolet sterilizer is dispensed while in the absence of a vend cycle the water passing through the ultraviolet sterilizer is passed back into the storage tank. The apparatus further includes an arrangement for selectively adding to the dispensed water minerals for enhancing its taste and in addition an arrangement for selectively adding to the dispensed water electrolytes normally lost by a person during athletic or other strenuous activity.

Method of manufacturing and processing alcoholic beverages, and alcoholic liquids obtained by performing the method

Abstract: An alcoholic liquid obtained by fermenting a must or a wort is initially subjected to ultrafiltration or to reverse osmosis to obtain a permeate which contains a higher proportion of water and alcohol than the starting liquid and a concentrate which contains a higher proportion of the substances that flavor the starting liquid. The permeate is then subjected to reverse osmosis using a membrane which is substantially impermeable to alcohol, while still being permeable to water. The concentrate from the second step is added to the concentrate from the first step to produce a liquid which has a higher concentration of alcohol than the starting liquid. The resulting liquid may be useable at said higher concentration as a beverage, or it may be used for transport and/or for storage, with water being added to thereto to restore the beverage substantially to its starting condition before being drunk.

Dynamically formed membranes

Abstract: Dynamic membranes are obtained by coating on a porous polymeric substrate containing functional groups a chemically reactive hydrophilic polymer from a dilute aqueous solution under pressure and crosslinking said polymer present on the porous substrate as thin layer with low molecular polyfunctional compounds. The new membranes show good solvent and compaction resistance and resistance to separation of the individual layers. They can be used in ultrafiltration and reverse osmosis processes.

Treatment of landfill leachates by reverse osmosis

Abstract: High-strength landfill leachates and industrial wastes can be successfully renovated using a reverse osmosis process system subsequent to pretreatment.

Method of reverse osmosis employing an improved porous glass membrane

Abstract: A porous glass membrane for reverse osmosis desalination of salt water is made by heating a membrane of a sodium-boron-alumino silicate glass so that it separates into two inter-connecting phases, removing one phase to make the membrane porous, and then coating the pores with a metal oxide to modify the pore size distribution and strengthen the membrane to enable it to withstand the high pressure applied in the reverse osmosis process. The porous glass is first treated with a volatile metal chloride such as titanium chloride, and the resulting surface layer is hydrolyzed to produce the metal oxide coating. A further reduction in pore size with an accompanying increase in strength can be made by partially sintering the treated membrane.

Mechanism of pore formation in reverse osmosis membranes during the casting process

Abstract: The process of pore formation during the casting of reverse osmosis membranes is analyzed. The process consists of two steps. The first step is the evaporation step, where the cast polymer solution is allowed to dry for 1 ∼ 100 s. The second step is the gel formation step, where the cast is soaked in water leaving behind the membrane in form of a gel. The evaporation step gives rise to a thin (∼0.1 μm) skin of high density and very small pores which is chiefly responsible for desalination. The gel forms the backing (∼100 to 250 μm) and contains large pores. It is shown that low evaporation rates accompanied by shrinkage during evaporation gives rise to an instability leading to the formation of the skin region. The evaporation effect is fast, is confined to the skin region, and gives rise to very small pores. The gel formation is shown to be a very slow process which cannot interfere with the skin formation due to the vast differences in their rates of formation. It also gives rise to larger pores. All key features of the above experimental observations are explained. The kinetics of the process depend on the diffusion coefficients D and Dp of the solvent and the polymer. However, the main factor is the solution chemistry of the polymer-solvent system which controls both the effectiveness of the skin and the gel formed. For the first time, the relevant thermodynamic parameters which determine the extent and sizes of pore formation have been obtained.

Interfacial parameters governing reverse osmosis for different polymer material—solution systems through gas and liquid chromatography data

Abstract: In this paper interfacial properties governing reverse osmosis separations were studied by using gas and liquid chromatography data with respect to four cellulosic and two aromatic polyamide membrane materials. The data on interfacial water layer thickness obtained from gas chromatography were used together with equilibrium distribution constants obtained from liquid chromatography and reverse osmosis separation data to calculate the force constants associated with the electrostatic repulsion working on ionic solutes. The force constants were further used to calculate the average pore sizes (diameters) required for achieving 99.9% separation of sodium chloride by membranes made of the different materials studied. The theories and calculation procedures involved are illustrated.

Apparatus and process for desalination combining freeze concentration, centrifugation, and reverse osmosis

Abstract: Apparatus comprising a freeze exchanger in which an aqueous mixture is indirectly cooled by a cooling fluid to produce an aqueous mixture containing ice; a centrifuge; a conduit for feeding an ice slurry from the freeze exchanger to the centrifuge; a heater; a conduit for feeding ice from the centrifuge to the heater to melt the ice; a water treatment apparatus; a conduit for feeding the water from the heater to the water treatment apparatus to condition the water for contact with a reverse osmosis membrane; a reverse osmosis apparatus; and a conduit for feeding the conditioned water to the reverse osmosis apparatus in which the water is purified by reverse osmosis. A method comprising feeding an aqueous mixture into indirect heat exchange with a cooling fluid to produce ice particles in the aqueous mixture and thus to form an ice slurry; centrifuging the ice slurry to separate the ice and form an aqueous effluent; melting the separated ice and treating the resulting water to remove components which damage a reverse osmosis membrane; and subjecting the treated water to reverse osmosis using a reverse osmosis membrane to produce potable water and an impure water stream.

Concentration of radioactive liquid streams by membrane processes

Abstract: The possibility of concentrating radioactive effluents by reverse osmosis was investigated. Cellulose acetate membranes of the Loeb-Sourirajan type were used, and their performance was evaluated the CsCl and SrCl/sub 2/ solutions in concentrations ranging from millimolar to trace level. The applicability of solution-diffusion and irreversible thermodynamic models for predicting solute separation in the above concentration range has been investigated. Some aspects of the selectivity with reference to trace radionuclides are also reported.

Ionically crosslinked poly(acrylic acid) membranes. IV. Composite reverse osmosis membranes

Abstract: Composite reverse osmosis membranes of ionically crosslinked poly(acrylic acid) (PAA) have been prepared. The process consists of coating a porous polysulfone membrane with a thin layer of dilute solution of PAA, drying the thin liquid layer, and ionically crosslinking the PAA in solutions of different salts. The influence of some important preparation parameters on the properties of these membranes was investigated. It was found that all these membranes possessed ion exchange properties and could be ion exchanged; some of them have been found to be suitable for the desalination of low concentration salt solutions. By comparison to cellulose acetate (CA) membranes, higher rejection of phenols may be an interesting property of these membranes.

Treatment of water

Abstract: PURPOSE: To remove easily, economically and efficiently COD from water contg. bisulfite to be discharged from a reverse osmosis membrane separator for desalting by dispensing an alkali agent to said water under aeration of said water. CONSTITUTION: Condensate is introduced into the 1st tank 1a and the pH thereof is measured with pH 6a, and if the pH decreases to <4, a pump 7a is started to supply an alkali agent via a pipe 8a to the water to adjust the pH to 4W7 and to treat the water for 5W10min. The water is then introduced into the 2nd tank 1b, where the water is treated for 60W120min under the condition of 4W7pH to oxidize most of the bisulfate in the water. The treated water is introduced into the 3rd tank 1c, where the pH is maintained in a 6W8 range and the residual bisulfite ion and sulfite ion are finally treated to make the treated water match the level of the release water. The water in the tank 3 is stagnated for 5W 30min. COD is thus considerably reduced and the treated water is released from the 3rd tank to the outside of the system. COPYRIGHT: (C)1984,JPO&Japio

Reverse osmosis of soluble fraction of corn stillage

Abstract: Reverse osmosis of a soluble fraction of corn stillage with 1.1% solids in a laboratory unit yielded 76% of the initial volume as permeate, which contained only 4.6% of total solids and 3.2% of total N of the soluble fraction. Conductivity of the permeate was 68% that of tap water, but it increased with soluble contents of the stillage. Soluble fractions of stillage from fermentations using recycled stillage solubles contained much higher salts than ordinary stillage. On reverse osmosis, this fraction (with 4.4-6.6% solids) yielded 56-62% of original volume as permeate, which contained 10-18% of the total solids and 3.2-10% of the total N of the soluble fractions. Ultrafiltration before reverse osmosis extends the concentration range for reverse osmosis.