Showing papers on "Reverse osmosis published in 1989"

Economic evaluation of preconcentration in production of ethanol from dilute sugar solutions.

Abstract: The economic feasibility of preconcentrating dilute sugar solutions prior to fermentation is investigated. Two methods, evaporation and reverse osmosis, are compared. A computer program to determine the optimal preconcentration conditions for glucose solutions of 1.5–16 wt% has been developed. It was used to compute the fractional cost for labor and maintenance, preconcentration, fermentation, and distillation. Preconcentration with evaporation resulted in a higher total cost, compared with no preconcentration, for all cases studied, although a six-effect unit was used. Reverse osmosis was found to be economically feasible for preconcentration to about 5–10 wt % depending on the concentration of the feed.

Interfacially synthesized reverse osmosis membrane containing an amine salt and processes for preparing the same

Abstract: The present invention relates to an interfacially synthesized reverse osmosis membrane useful for the separation of fluid mixtures and solutions. In particular, the present invention relates to an aromatic polyamide water permeable membrane containing an amine salt therein, which is useful for desalination of an aqueous solution. The present invention also relates to processes for preparing the membrane.

Transportable apparatus for producing drinking water

Abstract: An installation for filtering drinking water out of contaminated water, which can be used in many different situations, as it consists of a hydrocyclone, a micro filter unit, a unit for reverse osmosis, a mixed bed ion exchange, a re-salting unit, a unit for ozonization, an activated carbon filter and a unit for chlorinization.

Water purifying and dispensing system

Abstract: A vending or dispensing system for providing purified water in response to a customer request is described. The water dispensing system has a water reservoir or tank containing first stage purified water and is provided with a subsystem for circulating water from the reservoir through a microbial sterilizer on at least a periodic basis for a predetermined period of time to maintain water quality within the tank. In one aspect, the water is passed through the microbial sterilizer before entering the tank for the first time as first stage water. Additional features described to insure water purity include flushing or rinsing the lines between a first stage water purification mechanism and the water reservoir prior to topping off the reservoir with purified water, and providing control mechanisms for ensuring that sump liquid cannot be suctioned back into the system. The purification mechanism, of which there may be more than one, may include, but is not limited to, an activated carbon filter, an ion exchange resin bed, a reverse osmosis (RO) filter and the like. The microbial sterilizer may include such equipment as one or more or multi-stage ultraviolet (UV) sterilizers. In one embodiment, the entire system is operated by a microcontroller in response to user commands.

Assessing Hollow-Fiber Ultrafiltration for Particulate Removal

Abstract: A pilot study was undertaken to evaluate the efficacy of membrane filtration for the removal of particulate material from two untreated water supplies in Northern California. The permeate produced by the hollow-fiber ultrafiltration module was assessed by monitoring four water quality parameters: turbidity, suspended solids, direct particle counts, and selected indicator bacteria. The study showed that the ultrafiltration process was very effective in removing particulates from both sources. It appeared that a constant final water quality in relation to particulate material was achieved regardless of the differences in concentrations or numbers of particles in the raw waters. Membrane technology is becoming increasingly popular as an alternative process in the drinking water treatment train. The anticipation of more stringent water quality regulations, a decrease in adequate water resources, and an emphasis on water reuse have made membrane processes more viable for drinking water treatment. As advancements are being made in membrane technology, capital and operation and maintenance costs decline, further supporting the use of membrane treatment techniques. Figure 1 presents various separation processes that are employed in water treatment and the typical size ranges of materials found in raw waters.’ The primary driving force behind the development of membrane processes for municipal drinking water supplies has been desalination, i.e., reverse osmosis (RO), in which high pressures have traditionally been used for salt removal. Recent advances have included the development of nanofilters or softening membranes that commonly use pressures in the range of 75-250 psi.2 Other membrane processes include ultrafiltration (UF) and microfiltration. Although UF has been employed for water treatment in manufacturing and other industries, its use as a treatment for drinking water is a recent concept. Only in the last 20 years have membranes been available on a commercial scale, and only in the last few years has UF of drinking water been regularly studied on a pilot scale. There are many potential advantages to treatment of drinking water by UF for liquid-solid separation compared with conventional treatment. These include production of a superior quality water, addition of fewer chemicals in the treatment process, lower energy requirements for operation and maintenance, and design and construc68

Isocyanurate crosslinked polyurethane membranes and their use for the separation of aromatics from non-aromatics

Abstract: The present invention is directed to non-porous isocyanurate-crosslinked polyurethane membranes. These membranes are useful for the separation of aromatic hydrocarbons from non-aromatic hydrocarbons. The separation can be performed using any commonly accepted membrane separation technique, e.g. reverse osmosis, dialysis, pervaporation or perstraction but is preferably performed under pervaporation or perstraction conditions.

Use of treated composite polyamide membranes to separate concentrated solute

Abstract: A method of separating water of reduced concentration of a selected solute via reverse osmosis, wherein the selected solute is sulfuric acid, sodium hydroxide, isopropanol, sodium nitrate or another solute having a much higher solute passage than sodium chloride. The reverse osmosis membrane is prepared by treating a crosslinked, polyamide discriminating layer with an amine-reactive reagent or compatible oxidant at conditions whereby the passage of the selected solute at a selected transmembrane pressure is reduced by at least 30 percent.

Self-filling bottled-water cooler

Abstract: A self-filling bottled-water cooler dispenses pure water from a transparent water bottle mounted on the top of a free-standing cabinet body. The cooler attaches to a tap-water or other continuous water source and provides a continuous supply of pure water without need to change the water bottle The free-standing cabinet body includes a water tank located within the upper portion of the cabinet body and at least one tap for dispensing water from the water tank. The water bottle is securely attached on the top of the cabinet body to the water tank such that water freely flows between the bottle and the tank. Water from the tap water or other source is purified in a reverse osmosis, carbon block or other water purifier and is routed to the water tank. An inlet valve connected to a float mechanism within the water bottle regulates the flow of purified water into the water tank. The fload mechanism closes the inlet valve only when the purified water in the water bottle is at or above a desired full level. A venting system prevents overfilling of the water bottle and a change in air pressure within the bottle whenever the level of purified water in the bottle changes.

Air dried cellulose acetate membranes

Abstract: The method of preparing dried asymmetric cellulose acetate blend membranes through the use of at least one drying agent which is a hydrophobic organic compound, such as polysiloxanes, hydrocarbons, ethers, ketones, chlorohydrocarbons or nitrohydrocarbons. The membranes are dried from their aqueous state by direct evaporation of water. The resulting air dried membranes are suitable for the desalination of water by reverse osmosis, non-­aqueous liquid separation, ultrafiltration, pervaporation, and for the separation of various gaseous mixtures into their constituent parts.

Reverse osmosis system and automatic cycling booster pump therefor

Abstract: A reverse osmosis system including a reverse osmosis filter with a reverse osmosis membrane and having an inlet port coupled to a source of feed water under predetermined pressure via a feed water inlet conduit, a product water outlet port for filtered outlet product water, and a brine outlet port for brine. A pump coupled into the feed water inlet conduit between the source of feed water and the inlet port of the filter and driven by the feed water under pressure. The pump increases the pressure of the feed water so that the reverse osmosis filter receives feed water at an increased pressure.

Reverse osmosis membrane characteristics for partitioning triglyceride-solvent mixtures

Abstract: Residual free gossypol in hexane-extracted cottonseed meal is a frequent concern of the feed industry. It is known that ethanol can efficiently extract the gossypol from cottonseed. However, regeneration of ethanol from ethanol-rich miscellas by conventional evaporation is costly, due to the high latent heat of ethanol. As an alternative to the evaporative regeneration, reverse osmosis (RO) has been investigated. It was found that commercially available RO membranes which have pore diameter around 20 A‡ (evaluated with deionized water flux) or less perform the necessary partitioning. Among the commercially available RO membranes, cellulose acetate (CA) type membranes with a nominal MWCO (molecular weight cutoff) value between 500 and 1000 were found to be efficient in partitioning the cottonseed triglycerides from the base solvent, but were not chemically compatible with the base solvent. RO membranes made from aromatic polyamide (PA) with MWCO value 1000 were found to have both the chemical stability and the necessary pore characteristics. Experimental results indicated the potential use of RO membranes for the regeneration of ethanol from ethanol miscellas. The required membrane pore characteristics and applicable permeate flux equations are discussed.

Spacerless feed channel membrane filter element

Abstract: A reverse osmosis filtration device which comprises a flexible elongated membrane bladder spirally wrapped around a purified water duct in a series of spaced-apart coils supported about their edges by perforated spacers. The device is installed in a water supply conduit to extract a volume of purified water under typical household line pressure while allowing the brine-carrying feed water for other normal household usage such as clothes and dishwashing, toilet flushing, showering and bathing.

Reverse osmosis as final filter in ultrapure deionized water system

Abstract: An improved deionized water treatment system and method that consists of using a first and second water treatment train wherein the second train improves water quality by reducing particulate and total organic carbon by means of a reverse osmosis membrane assembly. The final pure water having particulate sizes less than one micron and a total organic carbon measure of less than one part per billion.

Low and non-alcoholic beverages produced by simultaneous double reverse osmosis

Abstract: Simultaneous double reverse osmosis process for production of low and non-alcoholic beverages, particularly wines, from any traditionally fermented table wine feedstock. A portion of the feed wine is subjected to remove alcohol and water as a permeate, with recycle of the concentrated retentate, while simultaneously a volume-balanced amount of reverse osmosis water is input back into the feed tank to maintain the in process wine at the initial level of the feedstock wine. The process may be run batch-wise, alternately, or in a modified semi-continuous operation to produce non-alcoholic wines (wines having residual alcohol content of less than 0.01% by volume) low alcohol wires (less than 0.5 volume percent alcohol), or wines having reduced alcohol content (less than 11-13 volume percent). The process also overcomes the 5% alcohol barrier problem of conventional reverse osmosis. The resulting finished wine has flavor, aroma and color solids concentrations of a level acceptable in good commercial practice. Actual non-alcoholic wine produced by the process has won a gold medal in a blind professional taste test.

Dual stage filter cartridge for a reverse osmosis purification system

Abstract: A dual stage filter cartridge is provided for use in a reverse osmosis water purification system or the like. The filter cartridge includes a first stage having a filter medium for removing selected contaminants from incoming feed water, and a second stage including a reverse osmosis membrane for converting a portion of the filtered feed water to a relatively purified water supply. The filter media in the first state is particularly selected to remove contaminants which are otherwise potentially harmful to the reverse osmosis membrane. The dual stage cartridge is configured as a single unit adapted for simple drop-in installation into an open-ended cartridge housing.

Membranes in Water Treatment

Abstract: Membrane technology, using reverse osmosis to treat drinking water, is a promising alternative to conventional treatment. The method is now being used for desalination in a growing number of U.S. applications, including the world's largest desalination plant that recently went on line in Yuma, Arizona. Other well-established membrane methods are nanofiltration and electrodialysis, although these techniques are just beginning to be used in the U.S. Ultrafiltration is another membrane technology that is just emerging. All are described, along with their appropriate applications for treating drinking water. There are also different types of membranes; their characteristics, such as molecular weight cutoffs, are defined. Advantages are listed, principal among them that fewer chemicals are needed. The method generates less sludge, reducing disposal problems. They also offer potential for reducing treatment plant size and thus cutting costs. A major drawback is that membranes can become fouled with materials such as iron manganese, clay, and other organic substances that physically plug the surfaces, reducing efficiency. Nonetheless, costs are becoming competitive with conventional methods and much research is now being conducted that will make membrane technology even more attractive.

Reverse osmosis purifies part of water supply for drinking - while remaining flow is used for less demanding domestic needs

Abstract: A supply of water of less than ideal quality is delivered to a purifier (5) holding one or more semi-permeable membranes (6) which with suitable differential pressure pass through the purifier a supply of pure drinking water. Additives such as flavour enhancing CO2 are electronically controlled. Water travelling past, but not through, the membranes is used for domestic purposes such as baths, toilet flushing etc. The purified water is delivered to a storage cotnainer, e.g. an expandible flexible bag (18) inside a rigid casing. If not used in a set period, e.g. 3 days, this stored water is returned to the domestic usage distributor. If the storage cotnainer is full, a counter-pressure is applied near the membrane to halt reverse osmosis and further pure water prodn. USE - Produces pure water, largely free of bacteria, at low cost.

Desalting Practices in the United States

Abstract: Examen de l'utilisation des techniques de dessalement pour approvisionner en eau potable les municipalites

Self-contained canister unit for filtering tap water

Abstract: A water filtering canister unit having self-contained reverse osmosis and activated carbon filtering systems which are adapted for connection onto the water tap in a home, apartment or office. The canister unit includes a housing defining an inner chamber in which a cylindrical reverse osmosis membrane is mounted. Water molecules which pass through the membrane continue through a capsule containing a body of activated carbon particles and thence outwardly through a discharge conduit. Dissolved salts and minerals as well as particulate matter rejected by the membrane are discharged in brine water at a controlled rate through a lower end cap on the housing.

Surface-hydrophilic, highly selective semipermeable membrane

Abstract: A surface-hydrophilic, highly selective semipermeable membrane comprising a semipermeable membrane of a hydrophobic polymer and a hydrophilic segment having at least one end directly bonded to at least one surface of the semipermeable membrane is disclosed. The hydrophilic segment comprises at least one methylene group or substituted methylene group which is positioned at least at one end of the segment and at least one neutral hydroxyl group. The surface-hydrophilic, highly selective semipermeable membrane not only has excellent resistance to heat and organic solvents, but also non-adsorptivity for organic substances including even ionic organic substances. Therefore, the surface-hydrophilic, highly selective semipermeable membrane of the present invention can advantageously be used for microfiltration, ultrafiltration, reverse osmosis and dialysis.

Test Results on Reuse of Reclaimed Shower Water - A Summary

Abstract: Results are presented from tests to evaluate a microgravity whole body shower and waste water recovery system design for possible use on the Space Station. Several water recovery methods were tested, including phase change distillation, a thermoelectric hollow fiber membrane evaporation subsystem, and a reverse osmosis dynamic membrane system. Consideration is given to the test hardware, the types of soaps evaluated, the human response to showering with reclaimed water, chemical treatment for microbial control, the procedures for providing hygienic water, and the quality of water produced by the systems. All three of the waste water recovery systems tested successfully produced reclaimed water for reuse.

Method of manufacturing a reverse osmosis membrane and the membrane so produced

Abstract: Reverse osmosis membranes are manufactured by casting a polysulfone casting composition comprising: (i) an aromatic polysulfone derivative having repeat units, at least an average of about 20% of which are carboxylated and are of the formula I: ##STR1## , wherein each R in each formula is ortho to the sulfone, at least one R in each formula is a carboxyl group with any remainder thereof being hydrogen, and (ii) a solvent for the aromatic polysulfone derivative, then evaporating solvent from the casting composition and then gelling the casting composition into a reverse osmosis membrane. The permeability of the reverse osmosis membrane may be increased by the addition of a non-solvent for the aromatic polysulfone derivative to the casting composition.