Showing papers on "Forward osmosis published in 2008"

Method for designing membranes for osmotically driven membrane processes

Abstract: Osmotically driven membrane processes, such as forward osmosis (FO) and pressure retarded osmosis (PRO), rely on the utilization of large osmotic pressure differentials across semi-permeable membranes to generate water flux. The present invention relates to improved membranes for use in such osmotically driven membrane processes. Current generation polymeric membranes used in liquid separations are typically comprised of a selective barrier supported by a porous structure. This structure is not ideal for osmotically driven membrane processes unless certain membrane characteristics are tailored appropriately. The support layer porosity, thickness, tortuosity, and hydrophilicity all play a crucial role in water flux performance across asymmetric semi-permeable membranes. The membrane support layers must be thin, highly porous, non-tortuous, and/or hydrophilic if they are to be used in FO and PRO processes. These goals are to be accomplished without sacrificing water permeability and salt rejection. Various methods for making these new membranes are described herein.

Systems and methods for forward osmosis fluid purification using cloud point extraction

Abstract: A process for purification of fluids, for example, desalination of seawater or brackish water, using organic solutes in a concentrated water solution for use in a forward osmosis process, to extract fresh water out of salt water through the forward osmosis membrane, and subsequently separating the organic solutes out of the diluted forward osmosis permeate by cloud point extraction, thereby regenerating a concentrated organic solution for recycling to the forward osmosis process, and fresh water for potable water use.

System and Method for Demonstrating Water Filtration and Purification Techniques

Abstract: The present invention is a portable water filtration/purification system that may be used for educational purposes. It includes a plurality of stackable filtration/purification housings, each of which accommodates a different type of water filtration/purification subsystem. A pressurization cap connectable to each housing provides for pressurizing one, several or all housings stacked in a particular combination or sub-combination. The housings may be color-coded for easy identification of each the type of filter within a particular housing. The water filters or purifiers in the various housing may include, but are not limited to, a sediment filter, a carbon filter, a reverse osmosis filter, a forward osmosis filter, a chemical purifier (or purification sub-system), and/or an ultraviolet light water purifier (or purification sub-system).

Reverse osmosis membrane device

Abstract: PROBLEM TO BE SOLVED: To provide a reverse osmosis membrane device which can stably supply water having optimal water quality as boiler supply water without influence of a change in raw water quality, and differences of individual products, aged deterioration and the like of reverse osmosis membranes. SOLUTION: The reverse osmosis membrane device 10 comprises a reverse osmosis membrane module 11 for receiving raw water through a pump 13 installed in a raw water line 12 and having a treated water line 14 for discharging treated water obtained by removing impurities in the raw water and a concentrate line 15 for discharging concentrate containing concentrated impurities, a concentrate mixing line 16 connected between the concentrate line 15 and the treated water line 14 to mix a part of the concentrate with the treated water, a treated water quality detector 6 installed in the treated water line 14 to detect the water quality of the treated water, a flow regulating valve 8 installed in the concentrate mixing line 16, and a control means 20 for controlling the flow regulating valve 8 based on detection signals of the treated water quality detector 6. COPYRIGHT: (C)2010,JPO&INPIT

Modeling of external and internal concentration polarization effect on flux behaviour of forward osmosis

Abstract: The forward osmosis process has recently gained more interest from researchers and is being viewed as an alternative to various membrane processes. The primary challenge in developing the process is the severity of both external and internal concentration polarizations, which significantly reduce the water flux across the highly selective membrane. This study investigates the impact of concentration polarization on flux behaviour. A model adopted from the boundary layer concept was used to describe the external concentration polarization effect. A previously developed model for the internal concentration polarization was further improved from the governing convective-diffusion equations, to achieve a better transport model that was in excellent agreement with experimental flux data. Laboratory experiments were carried out to account for both the external and internal concentration polarization and the associated water flux was verified with the improved models. Results showed excellent agreement for both models, which were used to describe external and internal concentration polarization, and these modified models were more accurate than previously used models.

Membrane separation apparatus and method of operating the same

Abstract: PROBLEM TO BE SOLVED: To provide a membrane separation apparatus and a method of operating the same which can recover energy of high-pressure concentrated water discharged from a reverse osmosis membrane cartridge with high efficiency, can optimally control the whole power consumption of the membrane separation apparatus, and can stably supply the required flow rate of diluted water with optimum control while securing appropriate water quality. SOLUTION: The membrane separation apparatus is provided with a supply seawater bypass line 15 for joining raw water pressurized by a positive displacement energy recovering device 5 with high-pressure raw water flowing through a high-pressure line 10 using the energy recovering device 5, a booster pump 6, a temperature sensor 43, and a controller 7 for controlling the flow rate of supply raw water. The controller 7 controls the flow rate of the raw water supplied to the reverse osmosis membrane cartridge 4 so as to obtain the preset diluted water flow rate Q 1 , by using raw water temperature detected by the temperature sensor 43, the membrane characteristics of a reverse osmosis membrane 4a of the reverse osmosis membrane cartridge 4 on temperature, a relationship between the concentration of solutes in the raw water and reverse osmosis, and a relationship between the performance curves of a high-pressure pump 3 and the booster pump 6. COPYRIGHT: (C)2010,JPO&INPIT

Method for the treatment with reverse osmosis membrane

Abstract: A method for treatment with a reverse osmosis membrane to reduce decrease in flux that occurs even under the conditions that water supplied to a reverse osmosis membrane treatment apparatus contains only a trace amount of iron and that the formation of scales of substances such as calcium and silica is prohibited. A method for performing a treatment with a reverse osmosis membrane to treat raw water containing iron at 1000 μg/L or less as total iron with a reverse osmosis membrane, including a step of adding a compound having a sulfo group to the raw water.

Water purification method using a field separable osmotic agent

Abstract: A method of obtaining purified water from an impure water source comprises, contacting the impure source through a semi-permeable membrane with a higher osmotic potential draw solution containing a field separable osmotic agent —comprising one or more ionic salts and/or a superparamagnetic nano-particle bound to a hydrophilic polymer — maintaining contact to allow a net flow of water to into the draw solution and carrying out magnetic and/or electric field separation to remove the osmotic agent from the draw solution. The use of one or more ionic salts as field separable osmotic agents in forward osmosis processes is also disclosed and an osmotic agent comprising a superparamagnetic nano-particle bound to a hydrophilic polymer. The electric field separation is preferably carried out using capacitive deionisation wherein the electrode is made of nanoporous carbon and preferably a single ionic salt, such as Magnesium, MgCl2, or Calcium Chloride, CaCl2, is used. The superparamagnetic nano-particle is preferably iron based and may be magnetite (Fe3O4) or maghemite (γ-Fe2O3) or a mixture thereof.

Ligand based forward osmosis

Abstract: Forward osmosis methods and apparatus using a supported osmotic agent to establish or enhance an osmotic forward bias are disclosed. A supported osmotic agent may be assisted by osmotic agents not attached to a support and/or a pressure differential between an influent and effluent chamber and/or a temperature gradient and/or other means to increase the osmotic pressure in an effluent chamber.

A Feasibility Study of Pressure Retarded Osmosis Power Generation System based on Measuring Permeation Volume using Reverse Osmosis Membrane

Abstract: Pressure Retarded Osmosis (PRO) power generation system is a hydroelectric power system which utilize permeation flow through a semi-permeable membrane. Permeation flow is generated by potential energy of salinity difference between sea water and fresh water. As membrane cost is expensive, permeation performance of membrane must be higher to realize PRO system. We have investigated Reverse Osmosis (RO) membrane products as semi-permeable membrane and measured permeation volume of a few products. Generation power by membrane area calculated from permeation volume is about 0.62W/m2. But by our improvements (more salt water volume, spacer of fresh water channel with a function of discharging concentrated salinity, extra low pressure type of membrane, washing support layer of membrane when generation power reduces to half), generation power may be 2.43W/m2. Then power system cost is about 4.1 million yen/kW. In addition, if support layer of membrane makes thinner and PRO system is applied to the equipment that pumping power on another purpose is avairable (wastewater treatment plant located at the seaside, thermal and nuclear power plant or sea water desalination plant), generation power may be more. By these improvements PRO system may be able to realize at the cost close to photovoltaic power system.

The Use of Ion Exchange Resins in a Forward Osmosis Desalination System for the Softening of Feed Water

Abstract: Ion exchange (IX) softening of feed seawater in a pretreatment unit prior to desalination by reverse osmosis (RO) can decrease membrane scaling, consequently reducing maintenance costs and increasing efficiency. This research determined whether the brine produced in desalination systems could be used to regenerate IX resins for feed water softening. If this is possible, then, instead of being a waste product, the brine could be used beneficially. This hypothesis was tested by comparing the water hardness levels of the softened seawater to untreated seawater. Further experiments were carried out to determine whether softened seawater increased the efficiency of RO desalination systems after the first five uses of the system. The experiments were limited to the study of the first five uses because of the quality of the RO membranes readily available for this work. Longer testing periods with higher quality membranes would likely yield more meaningful results. It was demonstrated that RO brine can effectively regenerate IX resins used for desalination pretreatment, suggesting that this softening method can be used for RO desalination systems in industrial settings. The experimental results showed that softening of IX feedwater with desalination brine did not decrease the efficiency of RO desalination systems during the first five uses of the desalination system, demonstrating that membrane systems are effective for emergency purification applications.

The performance of reverse osmosis membrane in water treatment

Abstract: Membrane technology has led to a new focus on water and wastewater treatment. This is due to severaldrawback of the conventional water treatment i.e release the toxic and carcinogenic materials. In thisresearch, the use Reverse Osmosis (RO) membrane for treating river and well water to obtain clean anddrinking water was studied. The variables studied were effect of pressure and operation time to themembrane flux. The pressure was varied from 1 to 7 bar and the operation time was varied from 15 to 60minutes. The content of Total Dissolved Solid (TDS) in the permeate product was analyzed. The resultsshown that the increase of pressure would increase the membrane flux and decrease TDS. The increaseof the operation time would decrease membrane flux and TDS. The reverse osmosis membrane wassuccessfully applied to treat the river and well water. The product fulfill national standard quality ofdrinking water by viewpoint of the TDS content

Getting the Most From Your Brackish Groundwater: Alternatives for Treating RO Brine to Increase Recovery and Reduce the Volume for Disposal

Abstract: EMWD recently completed two brine treatment studies, one for the California Department of Water Resources (DWR) and the other for the United States Department of Interior, Bureau of Reclamation (USBR). These studies investigated the cost of different alternative process treatment trains to recover additional usable water from primary reverse osmosis (RO) brine, and either reduce the volume of brine significantly, or go to complete zero-liquid discharge (ZLD). The studies included pilot scale, bench scale and desktop evaluations of both established and emerging technologies for brine treatment. Chemical softening of primary RO brine followed by either a second RO process or electrodialysis reversal (EDR) is an example of so-called established technologies; emerging technologies investigated included membrane distillation (MD), forward osmosis (FO) and seeded reverse osmosis. A 50-gpm chemical softening process was operated for 6-months and provided feed water to RO and EDR pilot units. MD and FO were tested at bench scale, and seeded RO was operated in a batch pilotplant. Capital and OM probably because of the capital costs associated with selective precipitation and washing and processing of the salts. Treatment trains that included a third concentration step (using the seeded RO process) ahead of thermal mechanical evaporation appeared to have slightly lower overall costs. This is attributed to the reduced size of the thermal evaporation process. Additional work on MD, FO and the seeded RO processes is needed.

Reverse Osmosis System with Dual Water Intake

Abstract: Disclosed is an improved multi-state reverse osmosis system with dual water inlets for improving filtration efficiency. More specifically, the system includes a pressure vessel with a series of semi permeable membranes. A seawater inlet is included at both a first end of the vessel and at an intermediate location. By re-supplying seawater at the intermediate location, a minimum seawater pressure is maintained throughout the entire length of the vessel. This, in turn, results in increased filtration efficiency.