Showing papers on "Reverse osmosis published in 2003"
TL;DR: In pressure-driven membrane processes, a pressure exerted on the solution at one side of the membrane serves as a driving force to separate it into a permeate and a retentate as discussed by the authors.
Abstract: In pressure-driven membrane processes (reverse osmosis, nanofiltration, ultrafiltration, and microfiltration) a pressure exerted on the solution at one side of the membrane serves as a driving force to separate it into a permeate and a retentate. The permeate is usually pure water, whereas the retentate is a concentrated solution that must be disposed of or treated by other methods. Membranes may be polymeric, organo-mineral, ceramic, or metallic, and filtration techniques differ in pore size, from dense (no pores) to porous membranes. Depending on the type of technique, salts, small organic molecules, macromolecules, or particles can be retained, and the applied pressure will differ. This paper reviews the principles behind the different techniques, the types of membranes used, rejection mechanisms, and process modeling. Applications of pressure-driven membrane processes are also considered, including reverse osmosis and nanofiltration for the treatment of wastewater from landfills and composting plants, nanofiltration in the textile industry, and ultrafiltration and microfiltration in drinking water production and wastewater treatment.
Lastly, the paper discusses recent developments, including techniques to prevent membrane fouling by modifications affecting surface roughness or hydrophilicity/hydrophobicity, or by cleaning the membranes, and methods for treating or disposing of the retentate.
822 citations
TL;DR: A model that accounts for both hindered diffusion of salt ions and altered hydrodynamics within colloidal deposit layers is presented and successfully links permeate flux and salt rejection to cake-enhanced concentration polarization and provides new insight into the mechanisms through which salt-rejecting membranes foul.
Abstract: Results from well-controlled colloidal fouling experiments with reverse osmosis (RO) and nanofiltration (NF) membranes suggest the existence of a new source of flux decline for salt-rejecting membr...
598 citations
TL;DR: In this article, a POME treatment system based on membrane technology shows high potential for eliminating the environmental problem, and in addition, this alternative treatment system offers water recycling, the treated effluent has a high quality and crystal clear water that can be used as the boiler feed water or as the source of drinking water production.
460 citations
TL;DR: This paper reviews possibilities to treat or discharge the concentrate and general guidelines are given for the choice of a proper method as a function of the origin and composition of the water treated.
Abstract: Application of pressure-driven membrane processes (microfiltration, ultrafiltration, nanofiltration, and reverse osmosis) results in the generation of a large concentrated waste stream, the concentrate fraction, as a byproduct of the purification process. Treatment of the concentrate is a major hurdle for the implementation of pressure-driven membrane processes since the concentrate is usually unusable and has to be discharged or further treated. This paper reviews possibilities to treat or discharge the concentrate: (i) reuse, (ii) removal of contaminants, (iii) incineration, (iv) direct or indirect discharge in surface water, (v) direct or indirect discharge in groundwater, and (vi) discharge on a landfill. General guidelines are given for the choice of a proper method as a function of the origin and composition of the water treated. Next, the further treatment of the concentrates in four application areas of pressure-driven membrane processes (drinking water industry, leather industry, and membrane treatment of landfill leachates and of textile process waters) is discussed.
309 citations
TL;DR: In this article, a detailed comparative study was conducted for the energy recovery systems for seawater reverse osmosis (SWRO) plants available in the market, and suggestions were given for energy cost reduction as well as optimum membrane cleaning procedure.
296 citations
TL;DR: In this article, the authors demonstrated that the RO process could be very effectively applied for water denitrification and water desalination in a rural area and demonstrated that RO brine at approximately 50% water recovery should be suitable for stock watering if the conditions for water watering are met in terms of nitrate-nitrogen concentration, TDS and other constituent concentrations.
294 citations
TL;DR: In this article, the adsorption of hydrophobic compounds at low concentration (∼100 ppb) onto NF/RO membranes were tested under cross-flow conditions, and the experimental results demonstrated that a relatively large amount of the feed water needed to be filtered to reach saturation conditions.
281 citations
TL;DR: In this paper, the authors measured the ion transport and water flux across ultrathin multilayered polyelectrolytes under nanofiltration and reverse osmosis conditions.
Abstract: Measurements of ion transport and water flux across ultrathin multilayered membranes of polyelectrolytes were carried out under nanofiltration and reverse osmosis conditions. The polyelectrolyte membranes were prepared upon alternating electrostatic layer-by-layer adsorption of polyvinylamine (PVA) and polyvinyl sulfate (PVS) on porous supports. The pressure-driven transport of aqueous electrolyte solutions containing NaCl, Na2SO4, MgCl2, and MgSO4 in 1 and 10 mM concentration was investigated. For MgCl2 and MgSO4, a complete rejection was observed independently from the concentration of the feed solution and the pressure applied. For NaCl and Na2SO4, the rejections were 84 and 96% at 5 bar, and 93.5 and 98.5% at 40 bar, respectively. The hydraulic permeability of the composite membrane was 113.7 mL/(m2 h bar). It was only little affected by the presence of salt. At low and moderate pressure the membranes are suitable for water softening applications, while at pressures of 40 bar or higher they can be use...
263 citations
TL;DR: In this article, the authors consider the effects of water desalination on the local environment in the vicinity of the desalification plants and propose a planning approach to minimize the adverse effects of the process on the environment.
261 citations
TL;DR: The spiral wound membrane element configuration is the most widely used due to its high packing density and relatively low price as mentioned in this paper, and it has been widely accepted as a means of producing various qualities of water from surface water, well water, brackish water and seawater.
245 citations
TL;DR: In this article, a wide variety of organic pollutants including endocrine disrupting chemicals, plastic additives and low molecular weight priority pollutants from aqueous solutions by the use of many recent type nanofiltration (NF)/reverse osmosis (RO) membranes was investigated.
TL;DR: In this paper, a statistical factorial design was employed to identify more accurately the key factors as well as their interactions in both physical and chemical cleaning of ultrafiltration (UF) and reverse osmosis (RO) membranes in municipal wastewater reclamation.
TL;DR: In this article, a quick introduction to the boron problem and its relevance in seawater desalination is given, and four characteristic design concepts are discussed from an economic and technical point of view.
TL;DR: The character of bulk organics present in final SAT water resembles the character of natural organic matter present in drinking water, based on the characterization techniques used.
TL;DR: In this paper, a FilmTec FT30 membrane as a reverse osmosis membrane and a synthetic emulsion using an Iranian crude oil have been employed to investigate the mechanism of flux decline.
TL;DR: Hybrid RO-constructed wetland treatment systems present a viable alternative for treatment and reuse of produced waters from oil fields and assess the quality of treated water in terms of physicochemical characteristics and toxicity influencing reuse of the water for irrigation or other designated uses.
TL;DR: In this paper, a comparative study of four different polyamide membranes that were tested for their ability to reduce the concentrations of pollutants in a synthetic effluent stream containing acrylnitrile and three inorganic species (sulphate, ammonium and cyanide).
TL;DR: A desktop profeasibility study using data from Petroleum Development Oman (PDO), operating plants in Bahja, Rima, Nimr and Marmul, confirmed the technical feasibility of treating reject brines in simple processing routes using SAL-PROC technology as discussed by the authors.
TL;DR: In this article, the chemical reactivity of thin-film composite reverse osmosis (RO) membranes was investigated and two chemical pathways for degradation were shown, one at constant pH and another that is pH-history dependent.
Abstract: Selected aromatic amides were used to model the chemical reactivity of aromatic polyamides found in thin-film composite reverse osmosis (RO) membranes. Chlorination and possible amide bond cleavage of aromatic amides upon exposure to aqueous chlorine, which can lead to membrane failure, were investigated. Correlations are made of the available chlorine concentration, pH, and exposure time with chemical changes in the model compounds. From the observed reactivity trends, insights are obtained into the mechanism of RO membrane performance loss upon chlorine exposure. Two chemical pathways for degradation are shown, one at constant pH and another that is pH-history dependent. An alternative strategy is presented for the design of chlorine-resistant RO membranes, and an initial performance study of RO membranes incorporating this strategy is reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1173–1184, 2003
TL;DR: In this paper, the speciation of silica in feedwaters, and chemical approaches to controlling fouling and maximizing silica reduction are discussed, and a brief review of geochemistry, the chemical and biochemical dissolution and deposition of Silica and silicates in nature is provided for insights and understanding of natural processes that can be applied to the task of process design and control.
TL;DR: In this article, an ion exchange membrane electrodialytic salt manufacturing plant (NaCl production capacity: 200,000 t per year) using brine discharged from a reverse osmosis (RO) seawater desalination plant is discussed.
Patent•
01 Aug 2003TL;DR: In this paper, the use of univalent anion and univalent cation selective membranes in the electrodialysis unit (300), the addition of a nanofiltration unit to process the diluate from the EDS unit (200) and the operation of the SDS unit at an elevated pressure.
Abstract: Sodium chloride and purified water are recovered by treating salt water that contains sodium chloride with an integrated reverse osmosis (200) and electrodialysis (300) system, which includes an efficiency-enhancing feature that is one or more of the following: the use of univalent anion and univalent cation selective membranes in the electrodialysis unit (300); the addition of a nanofiltration unit to process the diluate from the electrodialysis unit (300); or operation of the electrodialysis unit (300) at an elevated pressure. Magnesium and bromine can optionally be produced when the salt water contains these materials.
TL;DR: A pilot study in order to investigate the removal efficiency of dissolved matter and its fouling potential during nanofiltration and reverse osmosis of local groundwater that was pretreated with an ultrafiltration membrane system found that Fe seemed to be a great contributor to irreversible fouling.
Patent•
30 Jul 2003
TL;DR: In this paper, a vessel includes a water intake system, reverse osmosis system, concentrate discharge system, a permeate transfer system, power source, and a control system.
Abstract: Systems, methods, and apparatus for desalinating water are provided. A vessel includes a water intake system, a reverse osmosis system, a concentrate discharge system, a permeate transfer system, a power source, and a control system. The concentrate discharge system includes a plurality of concentrate discharge ports.
TL;DR: In this article, the performance of different pretreatment systems used in the seawater reverse osmosis desalination process is presented, including conventional media-filtration technique and non-conventional membrane filtration techniques.
Patent•
09 Jul 2003
TL;DR: An impulse-type wave motor as discussed by the authors employs a seabed-mounted or supported structure mounting a wave energy absorbing panel on a hinged lever arm for reciprocation motion to obtain optimal absorption of wave energy from wave motion in the sea.
Abstract: An impulse-type “wave motor” employs a seabed-mounted or supported structure mounting a wave energy absorbing panel on a hinged lever arm for reciprocation motion to obtain optimal absorption of wave energy from wave motion in the sea. For deepwater wavelengths of L, the panel is optimally positioned in a region within L/2 depth from the sea surface. The panel motion is coupled by a connecting rod to a fluid pump which generates a high-pressure fluid output that may be used to drive a reverse osmosis desalination unit or to produce other useful work. Seawater or brackish water may be desalinated through reverse osmosis membranes to produce water quality for consumption, agricultural, or other uses. The submerged operating environment of the device in a region of one-half the design wavelength provides the maximum available energy flux and forced oscillations. The pump may be of the positive-displacement piston type, plunger type, or multi-staging driver type, or a variable volume pump.
TL;DR: The MFI-UF was developed to include smaller colloidal particles not measured in the existing Silt Density Index (SDI) and MFI0.45 fouling indices as discussed by the authors.
TL;DR: In this article, the authors compared RO and ED in seawater desalination and showed that ED may compete with RO in the range of feed water salinity up to 8-10 g/L only because ED desaline cost is proportional to the amount of salt which must be carried through the membrane.
TL;DR: In this article, the salient results of an extensive investigation pertaining to selective alum recovery from water treatment residuals (WTR) using DMP are presented, where the authors show that DMP has not been tried to treat slurry or sludge with relatively high concentration of suspended solids or large organic molecules.
Abstract: Fouling of membrane surfaces by particulate matter and large organic molecules is relatively common for pressure-driven membrane processes, namely, reverse osmosis (RO), nanofiltration (NF), and ultrafiltration (UF). Donnan membrane process (DMP) or Donnan Dialysis is driven by electrochemical potential gradient across a semipermeable ion exchange membrane. Theoretically, DMP is not susceptible to fouling by fine particulates and/or large organic molecules. According to information available in the open literature, however, DMP has not been tried to treat slurry or sludge with relatively high concentration of suspended solids or large organic molecules. This study presents the salient results of an extensive investigation pertaining to selective alum recovery from water treatment residuals (WTR) using DMP. Water treatment plants use alum, Al2(SO4)3·14H2O, as a coagulant, alum being finally converted and discharged as insoluble aluminum hydroxide along with natural organic matters (NOM), suspended solids, ...
TL;DR: In this article, the authors describe pilot test results obtained on Mediterranean seawater using a 0.1 μm hollow fiber Microza ® module and show that seawater silt density index (SDI) ranged between 6 to non-measurable.