Showing papers on "Reverse osmosis published in 2001"
TL;DR: In this article, a review of the literature on concentration polarization in ultrafiltration and reverse osmosis is presented, with specific models such as surface renewal, and experimental methods such as laser-based refractometry, for quantification of the problem.
474 citations
TL;DR: In this paper, a technical and economical analysis of the application of a membrane separation technique for the purification of wastewaters aimed at their reuse is described, where the effluent from dyeing and finishing plants, after activated sludge oxidation, was treated at an 800 l/h by means of sand filtration, followed by a separation in an ultrafiltration membrane module.
Abstract: A technical and economical analysis of the application of a membrane separation technique for the purification of wastewaters aimed at their reuse is described. The investigation has been carried out by treating wastewaters of a pilot plant, reproducing on a smaller scale a separation system based on ultrafiltration and reverse osmosis. Significant indications for the exploitation of this approach on the fulling industrial scale were gained during the work. The effluent from dyeing and finishing plants, after activated sludge oxidation, was treated at an 800 l/h by means of sand filtration, followed by a separation in an ultrafiltration membrane module. The last separation step, reverse osmosis at 8 bar pressure, produced a permeate (60% of the inlet flow) that, relying on the analytical screening performed, was of much better quality with respect to process water presently in use. Therefore the permeate produced can be re-used in all production steps, including the most demanding ones concerning water quality such as dyeing with light coloration. A preliminary analysis of investment and operating costs also gave encouraging indications of the economic feasibility of the approach.
442 citations
TL;DR: Results show that nanofiltration is sufficient to eliminate refractory COD, the permeates have a COD lower than the requirements for discharge.
267 citations
TL;DR: In this paper, a simple model based on a solution-diffusion approach is proposed for predicting the pure solvent permeation through hydrophobic polymeric membranes, using molar volume and viscosity of the solvent as parameters.
260 citations
TL;DR: In this article, a general overview on the potentiality of membrane processes in the treatment of aqueous solutions coming from the leather industry is reported, which can be combined with or modified by membrane processes, such as microfiltration, ultrafiltration (UF), nanofiltration (NF), and reverse osmosis, on the basis of consolidated applications and experimental tests.
249 citations
TL;DR: In this paper, a review of the history of the development of membranes and membrane processes for water production in general and seawater desalination in particular is presented, highlighting some new trends observable in the following four areas; membrane development, membrane characterization, membrane transport and membrane system design.
233 citations
TL;DR: In this article, the authors used sand filtration and ultra-filtration as pre-treatments for a membrane process of nanofiltration (NF) or reverse osmosis (RO).
232 citations
TL;DR: In this article, the second law of thermodynamics in terms of the concept of exergy and its destruction is considered for desalination and the optimal design of the separation surface for minimum cost of energy and surface requirements is proposed.
227 citations
TL;DR: In this article, the authors compared the costs of water production with seawater reverse osmosis (RO) and showed that water costs in the range of 0.7 to 0.9 US $/m3 are achievable with RO or large distillation plants, depending on the seawater source and cost of available energy.
187 citations
TL;DR: In this paper, the salinity level of wastewater varied from 9.8 to 61.2 µm (1 µm/m = 640 mg/L) and various disposal methods were observed.
181 citations
TL;DR: In this paper, reverse osmosis membranes were fouled with water and a strategy for membrane regeneration is chemical cleaning of the fouled membranes using acid, alkaline, surfactant and detergent solutions.
TL;DR: In this paper, the authors analyzed the possibility of treating the permeate water in a way that increases the pH by means of conventional reverse osmosis and showed that this method only reduced the boron content by 60%.
TL;DR: In this paper, the effects of surface modification of commercial reverse osmosis polyamide membranes were studied in terms of flux/rejection and surface properties, and the results showed that the modified polyamide polyamide showed better resistance to fouling by hydrophobic foulants.
TL;DR: Analysis of the retention of halide salts reveals that small ions like fluoride are the best retained, and that the selectivity desalination of fluorinated brackish water is hence feasible and drinking water can be produced directly at much lower cost by optimizing the pressure for the type of water treated.
TL;DR: A reverse osmosis (RO) plant with an average daily drinking water production of 0.8-3 m3/d was installed by the Aachen University of Applied Sciences and the Energy and Water Research Centre of the Canary Islands Technological Institute (CIEA-ITC) at the test fields of the Spanish institute in Pozo Izquierdo (Gran Canaria Island).
TL;DR: In this article, two thin membranes cut from a cubic cell of ZK-4 zeolite were used as the semi-permeable membranes to separate water from aqueous NaCl solutions.
Abstract: A recently developed molecular simulation scheme for studying solutions undergoing osmosis and reverse osmosis was used to study the separation of aqueous solutions using thin zeolite membranes. This method allows for the preservation of the atomic roughness of the membranes, while the molecules that constitute the membranes are also allowed to vibrate. In the simulations, two thin membranes cut from a cubic cell of ZK-4 zeolite were used as the semi-permeable membranes to separate water from aqueous NaCl solutions. Both osmosis and reverse-osmosis phenomena were observed. The study showed that ZK-4 zeolite membranes show promise for use in membrane-based separation of aqueous electrolyte solutions, as well as other similar systems.
TL;DR: In this article, a reverse osmosis (RO) plant running on photovoltaic (PV) modules is described. And the results of the first laboratory tests are used for tuning a mathematical model of the system based on the I-V characteristics of the PV modules.
TL;DR: In this paper, the effect of polyvalent cations and anions in reverse osmosis (RO) systems was examined and the results showed that the presence of silica and its ability to foul membranes significantly limits the use of bearing waters for desalination and when used it has many economic penalties.
TL;DR: A simple transport model based on the solution-diffusion model incorporating concentration polarization is used to interpret the experimental results and predict rejection over a range of operating conditions.
TL;DR: In this article, the authors reported measured boron permeabilities and their relation to salt permeabilities using cross-linked polyamide membranes and calculated borons in the permeate were then calculated using a computer program that was based on the borón permeabilities calculated from the measured salt permeability.
TL;DR: All the advantages of reverse osmosis disappear if you speak about using domestic systems where qualified engineering provision is impossible, and Asymmetrical electrodialysis (EDA) is proposed which in domestic units showed itself to advantage quite effectively.
TL;DR: In this paper, a model based on a dusty-gas model of gas transport through porous media showed good agreement with the experimental results over the entire range of feed temperatures and recirculation rates studied.
TL;DR: In this article, structural and surface chemical characterizations of both active and porous sublayers of a composite polyamide/polysulfone reverse osmosis membrane were carried out by different techniques: (i) electrochemical impedance spectroscopy (EIS) allows both electrical and geometrical characterizations using equivalent circuits as models; (ii) surface chemical composition of the active layer was determined by X-ray photoelectron spectroscopic (XPS); (iii) salt diffusion, tangential streaming potential and membrane potential measurements allow the determination of different transport and
TL;DR: In this paper, the benefits of wastewater reuse for industrial and municipal applications are discussed and demonstrated using continuous microfiltration (CMF) pretreatment to reverse osmosis (RO) systems.
TL;DR: In this article, the nominal performance of composite seawater membrane elements has improved significantly, and new effective water microfiltration technologies have been introduced commercially, which can be utilized to improve the quality of surface seawater feed to the level comparable to, or better than the water quality from the well water sources.
TL;DR: In this article, the effect of pH on fluoride removal and the mechanism has also been discussed, as well as the effects of the pH on the removal rate of fluoride from water.
Abstract: Drinking water containing fluoride above a level of 1 mg/dm 3 is considered to be unsafe for human consumption. Higher intake of fluoride can cause potential health hazards. The conventional processes of fluoride removal from water are ion exchange, reverse osmosis and electro-dialysis. However, the utility of these processes has been limited due to their expensive operation and subsequent disposal problem of the waste brine generated. Defluoridation of water samples by coal-based sorbents was studied at different adsorbent dosages. First-order adsorption rate constants using the Lagergren equation, the Freundlich adsorption isotherm, the Langmuir adsorption isotherm, film diffusion and pore diffusion coefficients have been evaluated for each system. The effect of pH on fluoride removal and the mechanism has also been discussed.
TL;DR: In this paper, the authors outline the pretreatment steps involved in preparing the water to enter the RO membranes, with particular emphasis on filtration, which is considered the heart of the pre-treatment process.
Patent•
09 Aug 2001
TL;DR: In this paper, an under-counter water treatment system is described, where water from an outside supply source, such as a municipal water line, is provided to user's home, and water is removed from the tank by releasing an appropriate valve when the user wishes to drink the water.
Abstract: An under the counter water treatment system. Water from an outside supply source, such as a municipal water line, is provided to user's home. A prefilter (41) to remove sediment, organic compounds, and certain pollutants is first provided. After the prefilter, the water enters a reverse osmosis system (42) which includes an osmotic membrane. The reverse osmosis membrane filters out impurities and very small particles to provide highly purified water. The outflow of the reverse osmosis filter is stored in a water tank (44). Water is removed from the tank by releasing an appropriate valve when the user wishes to drink the water. When the water exits the tank, it passes through an electrolytic cell (36) having a plurality of plates. Current passes between the plates, and thus through the water flowing between the plates. This has several effects on the water including creating oxygen in the water, inserting free electrons into the water, as well as improving the taste, and affinity of the water for accepting other minerals. After passing out of the electrolytic cell, the water may pass through a final treatment stage (45) after which it is provided at an outlet tap for consumption by an end user. The flow of electricity to the plates is controlled in three modes of operation. During the first mode of operation, power is provided to the plates for a selected period of time after which the switch is first depressed. After the selected period of time has passed, control of power to the plates is linked to the actuation switch itself during a second mode of operation. If the switch remains on for an extended period of time, the electronic controls enter a third mode of operation during which power is automatically terminated to the electrolytic cell.
TL;DR: The ZeeWeed® 1000 as discussed by the authors is a new version of the original ZEEWeed immersed membrane designed to minimize life cycle costs and is used for seawater ultrafiltration.
TL;DR: In this article, the influence of the main parameters on the levelized cost of fresh water was analyzed: climatic conditions, nominal power of the wind turbine, salt concentration of seawater or brackish water, design arrangement, operating conditions, plant capacity, cost of reverse osmosis modules and cost of wind turbines.