Showing papers on "Reverse osmosis published in 1985"

Bacterial Adhesion and Fouling of Reverse Osmosis Membranes

Abstract: Adhesion of selected bacteria to cellulose actetate (CA) reverse osmosis (RO) membranes used in wastewater reclamation processes was investigated to determine its role in membrane fouling and reduced process efficiency. Adhesion of a hfycohcterium sp. previously isolated from an early stage of RO membrane biofouling was relatively unaffected by large variations in the ionic strength or pH of the buffer system. However, trace quantities of a polyoxyethylene ether nonionic detergent almost completely inhibited attachment. The mycobacteria were found to adhere to the CA membrane surface (or to a CA-affinity column) approximately 2.5fold more effectively than a wild-type strain of Escherichia coli The ability of Mycobucterium and E. coli to adhere to the membrane was correlated with their relative surface hydrophobicities as determined by their affinities for n-hexadecane. A similar correlation was established between a hydrophilic wild-type strain of Acinetobactev phos&devorus containing a single 17.8 mega-Dalton plasmid (PYGl) and a more hydrophobic isogenic derivative strain (P7P-) lacking the PYGl plasmid. Unlike the P7WT parent strain, the P7P-derivative produced more fimbrialike appendages, which may account for its enhanced hydrophobic and adhesive properties. The results suggest that hydrophobic interactions between bacterial cell surface components and the CA membrane surface play an important role in the initial stages of bacterial adhesion and RO membrane biofilm formation. The reuse of municipal and industrial wastewaters is considered an essential component of modern water management practices. This is especially true in arid Middle Eastern countries and in the southwestern region of the United States where potable and irrigation waters must be imported at great expense. The reclamation and purification of wastewater may be further justified in view of growing concern over the contamination of domesticgroundwater sources by a broad spectrum of anthropogenic organic compounds. Many of these compounds, particularly when chlorinated, exhibit mutagenic or carcinogenic activity in mammalian systems, and therefore pose a finite hazard to public health. Advanced chemical and biological treatment processes used in wastewater reclamation can significantly reduce the concentrations of potentially harmful organic compounds. The Orange County Water District (OCWD) operates an advanced wastewater treatment plant known as Water Factory 21, which is located near Fountain Valley along the Southern California

Process and system for producing sterile water and sterile aqueous solutions

Abstract: Water substantially free of pyrogens and microorganisms that meets the requirements of United States Pharmacopoeia Standard USP XX Water for Injection is produced by processing drinking quality water through a filtration step adapted to remove organic contaminants and impurities that degrade downstream seperation membranes, a reverse osmosis step to remove dissolved solids, pyrogens, microorganisms and chemical contamination, a deionization step to further remove dissolved solids, and an ultrafiltration step to remove pyrogens. A sterile filter to remove microorganisms increases the water quality to USP XX Sterile Water for Injection. Means are provided to periodically remove accumulated chemical contaminants, pyrogens and microorganisms from the reverse osmosis apparatus, the deionization apparatus and the ultrafiltration apparatus. The sterile water can be admixed with a sterile concentrate composition to produce a sterile dilute solution that can be packaged under sterile conditions.

Butanol fermentation liquor production and separation by reverse osmosis

Abstract: The problem of dilute solvent concentration in butanol-acetone fermentations can be solved by using reverse osmosis to dewater the fermentation liquor. Polyamide membranes have a potential application in a butanol-acetone fermentation and exhibited rejection rates as high as 98 percent. Optimum rejection of butanol in a fermentation liquor occurred at recoveries of 20-45 percent. Flux ranged from .05 to .6 L m/sup -2/ min/sup -1/.

Bacterial Colonization of Point-of-Use Water Treatment Devices

Abstract: Point-of-use water treatment devices were investigated to identify organisms that may colonize these filters, to determine the magnitude of the postcolonization release of microorganisms into the product water during daily use or after periods of nonuse, and to demonstrate the effect of tap water of marginal bacteriological quality on the quality of the product water. The bacterial count was found to vary between units of different design, between units of the same design, and between water samples from the same filter unit collected at different times of the day; it was affected by the length of time the filter cartridge had been in use, the design of the cartridge, and the temperature of the water, as well as by the species of microorganism. Installation and use by the public of in-the-home, point-of-use water treatment devices have increased in the United States during the last several years. This trend has paralleled increased consumer awareness of the potential health risks posed by some community drinking water systems. Interest in these point-of-use devices is usually based on a desire to improve the aesthetic quality of drinking water, including a reduction of thecontaminants that cause taste and odor, turbidity, hardness. and other undesirable effects. Manufacturers of point-of-use water treatment devices have estimated that some 6 million families already use their products and that the market is increasing. A study of the designs of commercially available point-of-use devices indicates that granular activated carbon (GAC) is often the major component for treatment; other components include ion exchange resins, spirally wound acrylicfilament spools, controlled-pore-size membranes for reverse osmosis systems, and paper filters. The quantity of activated carbon ranges from 30 g in a faucetmounted device to 266-593 g in the larger cartridges. Some designs precoat the carbon on a fibrous fluted material or press the carbon into a dense core rather than packing the cartridge bed

Method of performing osmetic distillation

Abstract: A hydrophobic semi-permeable membrane process (e.g., using hydrophobic microporous hollow fibers) for the concentration of a dilute solution of low osmotic pressure by osmotic distillation (also known as membrane distillation or membrane evaporation), which is a separation process using as its driving force the difference in the osmotic pressure between two fluids (e.g., fruit juice and seawater) separated by a hydrophobic semi-permeable membrane to achieve a concentration of the fluid having the lower osmotic pressure (.e., fruit juice). When coupled with reverse osmosis means there is provided a method for recovery of solvent (e.g., potable water) from the process, e.g., desalination of seawater. A process is also provided to recover part of the energy available between the two fluids i.e., between two different potential energies, due to the difference in osmotic pressure between the two fluids.

Production of low alcoholic content beverages

Abstract: Alcoholic beverages may be passed through a reverse osmosis system to form a permeate and a retentate. The permeate will comprise mainly alcohol and water and will be removed as will a minor portion of the retentate which is recovered as product. The major portion of the retentate is recycled back to the reverse osmosis system to admix with fresh beverage and added water. The product will comprise a beverage containing a lower alcoholic content than was possessed by the fresh beverage. The semipermeable membrane which is utilized in the reverse osmosis process will possess a chloride ion rejection rate greater than about 80% at 400 pounds per square inch net pressure.

Reverse osmosis water purifying system

Abstract: A reverse osmosis (R.O.) water purifier system that collects and stores pure water at low pressure and dispenses it at high pressure. Impurities left behind when the water passes through a R.O. module are disposed of by two methods: the fast flush method and the slow flush method. In the fast flush method, water entering a R.O. module may take two paths to escape therefrom. The first path constrains it to travel through a semi-permeable membrane in the module which filters out undissolved solids and which restrains the passage of dissolved liquids. The second path allows it to travel through the R.O. module, without passing through the membrane, thereby carrying out those impurities left behind by the water passing through the membrane. The purified water is directed to one side of a compartmented storage tank and the waste water from the module is directed to a control valve. From the control valve, the waste water may be directed through a restriction to a drain or it may be directed to the other compartment of the storage tank where the purified water is held. In the slow flush method, water enters a control valve, travels to the R.O. module, and has two paths of escape therefrom. The first path contrains it to go through the semi-permeable membrane in the R.O. module, and through a check valve to storage or outlet. The second path allows the water to escape through the R.O. module, thereby carrying to a drain the impurities left behind.

Reverse osmosis water purifier

Abstract: A compact reverse-osmosis water purifier especially adapted for use in the household on a counter-top, with an easy-to-operate diverter valve to connect the purifier to a water faucet and sink. A battery-operated pump is provided to dispense water from a storage reservoir. This reduces the size of the purifier unit while maximizing the height from the dispensing spout to the counter-top to accommodate relatively tall vessels for receiving the dispensed water. An automatic conductivity test device causes a red or a green lamp to be lit each time a button is pressed to dispense water, the green lamp indicating that the water is of sufficient purity, and the red lamp indicating that it is not, or that the device is malfunctioning or requires flush cleaning. The diverter valve can be operated to selectively pass water through the faucet in the usual way, or to feed water to the purifier. When in the condition to feed water to the purifier, outlet openings of different diameters can be selected, by operation of a rotary valve, to condition the diverter either for normal operation or for flushing the purifier.

Membrane-based liquid separation systems

Abstract: Comparaison des quatre procedes et de leurs applications: electrodialyse, ultrafiltration, osmose inverse, electrolyse

Orthophosphate-containing desalination scale inhibitors

Abstract: The instant invention is directed to a process for the control of scale formation and deposition in thermal or reverse osmosis membrane desalination plants, comprising adding to the water 0.1 to 100 ppm of (a) a water soluble orthophosphate and (b) at least one compound selected from the group consisting of water soluble polycarboxylates, phosphonates, phosphates, sulfonates and polyamides.

Process for treating waste water arising in coking or other coal upgrading processes

Abstract: The invention relates to a process for treating coking plant waste waters. According to the invention, the waste water is subjected to the following treatment stages: The waste water a) is heated, b) to it is added alkali, in particular alkaline earth metal compounds (for example Ca(OH)2 or Mg(OH)2) to liberate bound ammonia, c) the mixture is freed from degradable organic constituents, for example phenols, by extraction and/or absorptively and/or biologically, d) the waste water is subjected to a cross-flow filtration (CFF) in the ultrafilter to microfilter range for separating off colloidal and suspended particles and the concentrate is returned to the biological purification stage, e) the waste water is separated by reverse osmosis into a permeate and a concentrate, some of which is returned to the biological purification stage and f) the concentrate, following any vacuum evaporation, is returned to the coking process or another coal upgrading process and thus disposed of.

Characteristics of reverse-osmosis membrane fouling at the Yuma Desalting Test Facility

Abstract: Qualite de l'eau d'alimentation et composition des sediments qui encrassent les surfaces des membranes

Polyamides as barrier materials

Abstract: In the performance data of various polyamide and related membranes published to date there should be valuable information for molecular design of more excellent barrier materials. But at present a means for their evaluation and optimization is still not clear. One of the reasons may at least come from the competitive flood of proposals for the detailed mechanisms of reverse osmosis, e.g. the solution-diffusion model, the sieve model, the preferential sorption model and so on.109)