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Showing papers on "Reverse osmosis published in 1999"


Book
16 Dec 1999
TL;DR: Overview of membrane science and technology membrane transport theory membrane and modules concentration polarization reverse osmosis ultrafiltration microfiltration gas separation pervaporation ion exchange membrane processes - electrodialysis carrier facilitated transport medical applications of membranes other membranes processed.
Abstract: Overview of membrane science and technology membrane transport theory membrane and modules concentration polarization reverse osmosis ultrafiltration microfiltration gas separation pervaporation ion exchange membrane processes - electrodialysis carrier facilitated transport medical applications of membranes other membranes processed.

3,680 citations


Journal ArticleDOI
TL;DR: In this article, a process based on the selective removal of boron with resin has been evolved, and the pilot plant tests allowed an accurate cost assessment for the removal of BORON in the range of 4 to 6 US cents per cubic meter of permeate, dependent on the cost of the resin, the chemicals, and operation and maintenance.

196 citations


Journal Article
01 Jan 1999-Water SA
TL;DR: In this article, the presence of Al in drinking water with reference to its speciation, removal (treatment methods), water supply and health problems, and the regulation of its levels.
Abstract: Aluminium (Al) is one of the trace inorganic metals present in drinking water. In addition to the naturally occurring Al in raw waters, use of Al-based coagulants especially Al 2(SO4)3 (alum) often leads to an increase in treated water Al concentrations. A high (3.6 to 6 mg/l) concentration of Al may precipitate as aluminium hydroxide giving rise to consumer complaints. Al is also a suspected causative agent of neurological disorders such as Alzheimer’s disease and presenile dementia. During conventional water treatment processes, Al undergoes various transformations (also called ‘speciation’ of Al) which are influenced by factor s such as pH, turbidity, temperature of water source, and the organic and inorganic ligands present in water. Chemical precipitat ion, reverse osmosis, electrodialysis and cation exchange methods are efficient in Al removal from water. This paper gives an overvi ew of the presence of Al in drinking water with reference to its speciation, removal (treatment methods), water supply and health problems, and the regulation of its levels in drinking water.

178 citations


Journal ArticleDOI
TL;DR: In this paper, a real-time, non-invasive, in situ measurement of membrane fouling using ultrasonic time-domain reflectometry (TDR) is presented. But, the results show a good correspondence between the decline in the ultrasonic signal amplitude and the development of a fouling layer and suggest that ultrasonic TDR may be particularly responsive to fouling initiation and its subsequent removal during membrane cleaning.

162 citations


Journal ArticleDOI
TL;DR: In this paper, an experimental study describing the treatment of landfill leachate by means of a pilot-scale reverse osmosis unit was conducted. But the results showed that the rejection coefficient of COD was practically independent of the COD value, but was significantly affected by the applied pressure.

144 citations


Journal ArticleDOI
TL;DR: In this article, a modified steady-state solution diffusion model and an unsteady-state diffusion adsorption model are presented to predict flux and permeate concentrations from a single RO experiment.
Abstract: Predictive reverse osmosis (RO) models have been well-developed for many systems. However, the applications to dilute organic−water systems require the modification of transport models and the understanding of solute−polymer interactions. Studies with various substituted, nonionized phenolic compounds showed that these could cause substantial membrane water flux drop, even in dilute solutions with negligible osmotic pressure. Further, the organics could significantly adsorb on the cross-linked aromatic polyamide active layer. In some cases, even concentrations as low as 0.2 mM, 2,4-dinitrophenol (solution in particle-free, double-distilled water) can cause as much as a 70% flux drop with an aromatic polyamide membrane. Two models are presented in this paper: a modified steady-state solution diffusion model and an unsteady-state diffusion adsorption model which are able to predict flux and permeate concentrations from a single RO experiment. Further, the development of these models allows for the understa...

130 citations


Journal ArticleDOI
TL;DR: In this paper, an energy and exergy analysis of an integrated reverse osmosis (RO) + membrane distillation (MD) system where MD operates on the RO brine is considered for desalination processes.

117 citations


Journal ArticleDOI
TL;DR: In this article, an attempt at removal of nitrate ions from tap water by means of the combined processes of reverse osmosis and nanofiltration was made, but the efficiency of this process was limited mainly by the osmotic pressure of the retentate.

114 citations


Journal ArticleDOI
TL;DR: In this article, a dual-membrane process such as continuous microfiltration (CMF) followed by reverse osmosis (RO) is used to produce water that meets all drinking water standards.

110 citations


Journal ArticleDOI
TL;DR: In this article, integrated membrane operations such as the ones described above are analyzed for a seawater desalination system, and preliminary experimental results are discussed confirming the possibility of reaching an seawater recovery factor of 87%.

104 citations


Journal ArticleDOI
TL;DR: Polyamino polyether methylenephosphonate (PAPEMP) is an ideal additive for desalination operations because it simultaneously, controls calcium carbonate and calcium sulfate scale formation and deposition as discussed by the authors.

Journal ArticleDOI
TL;DR: In this article, the treatment of tanning wastewater was studied by means of reverse osmosis and ultrafiltration using membranes of polyamide and polysulfone (ultrafiltration).

Journal ArticleDOI
TL;DR: In this article, the effect of varied concentrations of additive polyvinylpyrrolidone on the performance of modified cellulose acetate/polyurethane blend membranes was studied.

Patent
01 Apr 1999
TL;DR: A reverse osmosis water purification system for providing potable water from a municipal water or other source containing undesired impurities is described in this article, where a motor driven pump supplies a feed stream to a reverse Osmosis unit resulting in the creation of a product water stream and a concentrate or brine stream.
Abstract: A reverse osmosis water purification system for providing potable water from a municipal water or other source containing undesired impurities A motor driven pump supplies a feed stream to a reverse osmosis unit resulting in the creation of a product water stream and a concentrate or brine stream The inclusion of a product water holding tank may be optionally omitted by routing the product water outlet stream directly to the tap via a branched line A pressure sensor causes a solenoid valve to open when the withdrawal of water from the tap is terminated, opening a valve in the branch line leading back to the pump The pump then continues to run, recirculating the product water stream to a mixing unit where it is blended with a major part of the concentrate stream that is being recycled and with make-up fresh water to create a composite feed stream As the system continues to run in this recirculation mode, the composite feed stream entering the purification unit becomes gradually purer, and once the quality reaches a desired level, the system is placed in shutdown mode Because of the high quality of the water on the feed side of the membrane in the reverse osmosis unit, little contamination of the purified water on the product side occurs during shutdown

Journal ArticleDOI
TL;DR: A sufficient chemical water purification treatment system should consist of ion exchange and reverse osmosis and attention has to be paid to the suitability of materials in contact with the water and of the chemicals used, for example regenerants or corrosion inhibitors.
Abstract: BACKGROUND The bacterial and chemical contamination of dialysate fluids are important problems in haemodialysis therapy and may be caused by the water used for dialysate preparation. METHODS We performed a survey of the microbiological and chemical quality of the water used in seven dialysis wards. Special attention was paid to the effects of each water treatment step, for example ion exchange, reverse osmosis and UV disinfection, on the number of bacteria (measured as colony forming units, CFU), the amount of endotoxin (endotoxin units, EU) and various chemical parameters, the main focus being on calcium, magnesium, sulphate, aluminium and heavy metals. RESULTS CFU values exceeding the European Pharmacopeia value, determined at an incubation temperature of 22 degrees C, were found in the samples of raw water (20.0%, n=25), after ion exchange (66.7%, n=12), after reverse osmosis (33.3%, n=18) and also in samples of the dialysis water taken at the inlets (12.5%, n=40) and outlets (50.0%, n=18) of the machines. Whereas all raw water samples from the wards showed high mean values for endotoxin (0.56-9.10 EU/ml) and the endotoxin levels were often enhanced after ion exchange (0.13- >9.49 EU/ml), treatment by reverse osmosis led to a satisfactory decrease in endotoxin in all samples (<0.03 EU/ml). Sufficient reductions in calcium, magnesium and sulphate could only be achieved by the combined application of ion exchange and reverse osmosis. Mercury contamination was observed in the samples after ion exchange at three treatment plants, this was possibly caused by polluted regenerants. Increased amounts of aluminium, copper and zinc were found in water samples from different sites in the treatment systems and were caused by materials in contact with the water. CONCLUSIONS A sufficient chemical water purification treatment system should consist of ion exchange and reverse osmosis. Attention has to be paid to the suitability of materials in contact with the water and of the chemicals used, for example regenerants or corrosion inhibitors. From the microbiological point of view, a safety UV disinfection step in the water-treatment system is favourable. To avoid bacterial recontamination periodic cleaning and disinfecting of the water-treatment and distribution systems, as well as the dialysis machine are essential. There is the need for complete guidelines regarding dialysis water that include all relevant chemical and microbiological parameters. Based on this standard, periodic examination of the water after each treatment step has to be performed.

Journal ArticleDOI
TL;DR: In this article, two applications to use unconventional sources for water production are described and the technical feasibility for this application has been shown and operational costs have been estimated on the basis of three pilot plant trails.

Journal ArticleDOI
TL;DR: In this paper, molecular dynamics simulations of water diffusion in a hydrated, amorphous polyamide have been carried out to study the effects of polymer dynamics, cross-linking, and hydrogen bonding interactions on the molecular mechanisms of diffusion.

Journal ArticleDOI
TL;DR: In this paper, the evaluation of various desalination technologies for the utilization of desalinated brackish water in Jordan was carried out using multi-criteria analysis, based on technical, economic, and environmental aspects.

Journal ArticleDOI
TL;DR: In this article, a porous catalytic membrane acting as a hydrogen diffuser is proposed as a means to solve these problems by creating an efficient three-phase contact between the catalytic surface, dissolved nitrate, and hydrogen gas.

Patent
18 May 1999
TL;DR: In this paper, the authors proposed a method for producing high quality reverse osmosis, nanofiltration, and ultrafiltration membranes in a high speed process using tandem coating techniques.
Abstract: A process for producing high quality reverse osmosis, nanofiltration, and ultrafiltration membranes in a high speed process provides membranes which have excellent rejection characteristics coupled with high flux capabilities. The process employs tandem coating techniques to coat a microporous substrate with a thin membrane on the order of 25 A to 1.0 microns. The tandem coating process comprises tandem offset gravure and subsequent slot die coating applicators, or alternatively comprises tandem slot die coating applicators. For reverse osmosis and nanofiltration membranes, a wet-on-wet coating process is used to coat a porous substrate first with an aqueous solution, and then with an organic solution to produce a cross-linked, interfacially polymerized composite membrane. Single slot coating applicators are utilized to produce ultrafiltration membranes.

Journal ArticleDOI
TL;DR: In this article, a post-treatment of secondary textile wastewater was tested at pilot scale on membrane modules (microfiltration MF, nanofiltration NF and reverse osmosis RO) for the direct reuse of polished effluent within the dyeing processes.

Journal ArticleDOI
TL;DR: In this paper, a simplified model was used to predict the performance of hollow fiber RO membranes based on the solution-diffusion membrane mass transport model and took into account the effect of the pressure drop in the fiber bore and in fiber bundle, the variation of the bulk solution concentration on the shell side of the fiber bundle and the concentration polarization.

Journal ArticleDOI
TL;DR: In this paper, a transport equation for a solution flow increasing due to osmosis inside a hollow cylindrical fiber is derived, which can be applied for either direct, pressure-retarded or reverse Osmosis, when the membrane is highly selective.

Journal ArticleDOI
TL;DR: In this paper, the possibility of reducing the volume of different types of animal waste waters by reverse osmosis was studied in a pilot plant and the volume reduction of waste water in cases where the urine had been collected separately in the shed and prevented from mixing with the faeces was 75-80%.

Patent
30 Jul 1999
TL;DR: A method of producing high purity water using weak acid cation exchange for dealkalization and a double pass reverse osmosis membrane system having enhanced membrane life is described in this paper.
Abstract: A method of producing high purity water using weak acid cation exchange for dealkalization and a double pass reverse osmosis membrane system having enhanced membrane life.

Journal ArticleDOI
TL;DR: In this article, the physical behavior of labneh was heavily dependent on the protein concentration and the severity of mechanical agitation during membrane treatment, and the higher protein content samples had more compact structure and smaller voids than their lower protein content counterparts.

Journal ArticleDOI
TL;DR: In this paper, an evaluation of the possibilities of using ultrafiltration as a pre-treatment for reverse osmosis, in a double membrane filtration scheme, in order to recycle biologically treated refinery effluent as cooling water make-up, is presented.

Journal ArticleDOI
TL;DR: In this paper, a new type reverse osmosis (RO) membranes and its process for seawater desalination were developed, which brought advantages of high water recovery, low energy cost and lower plant installation cost.

Journal ArticleDOI
TL;DR: In this article, an integrated membrane system (UF/RO) was developed to treat surface seawater, and the results showed that the Aquasource® UF membrane does not seem sensitive to high salinity of the seawater.

Patent
19 Mar 1999
TL;DR: A reverse osmosis water purification system comprises an impulse turbine operatively connected to a source of water to be purified as mentioned in this paper, where a feed pump is connected to the impulse turbine, and a second purification membrane chamber has an inlet for receiving the high pressure unpurified water from the feed pump.
Abstract: A reverse osmosis water purification system comprises an impulse turbine operatively connected to a source of water to be purified. A feed pump is connected to the impulse turbine to supply a source of high pressure water to be purified. A first purification membrane chamber is connected to the feed pump to receive a supply of high pressure unpurified water from the feed pump. The first purification membrane chamber has an outlet for discharging purified water and a discharge opening for discharging high pressure unpurified water. A hydraulic turbocharger has a turbine end T and a pump end P. The pump end P has an inlet for receiving the high pressure unpurified water from the first purification membrane chamber and an outlet which discharges the high pressure unpurified water. A second purification membrane member chamber is connected to the outlet of the pump end P of the hydraulic turbocharger for receiving the high pressure unpurified water. The second purification-membrane chamber has an outlet for discharging water purified in the second purification membrane chamber. The second purification membrane chamber has a discharge opening for discharging high pressure unpurified water from the second purification membrane chamber. The discharge opening is connected to the turbine end T of the hydraulic turbocharger and a turbine end T of the impulse turbine. The high pressure unpurified water from the second purification membrane chamber can be used to drive the turbine end T of the impulse turbine and/or the turbine end T of the hydraulic turbocharger to increase the pressure of the water to be purified that is supplied to the first or the second purification membrane chambers.