JP2015192979A - Water treatment apparatus using semipermeable membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of freshwater by forward osmosis using a temperature sensitive agent having a clouding point, which forms aggregates when heated, as attractant, capable of more efficiently separating the temperature sensitive agent aggregated by heating.SOLUTION: A water treatment apparatus includes: a forward osmosis membrane treatment apparatus 10 which allows water to be treated 1 to be contacted with an attractant solution 4 of a temperature sensitive agent dissolved in water through a semipermeable membrane 3 for the water in the water to be treated 1 to move into the attractant solution 4 through the semipermeable membrane 3, producing a water-diluted attractant solution 5 and a membrane concentrated water 2; first heating means 14 which heats the diluted attractant solution 5 flowing out from the forward osmosis membrane treatment apparatus 10 to a temperature equal to or higher than the clouding point of the attractant solution 5; a phase separation tank 11 in which the heated diluted attractant solution 5 is phase separated into a lower layer liquid 7 having a high concentration of the temperature sensitive agent and an upper layer liquid 6 having a lower concentration; cooling means 15 which cools the lower layer liquid 7 flowing out from the phase separation tank 11 to a temperature equal to or lower than the clouding point of the attractant solution 4; and a membrane filtration apparatus 12 for the membrane treatment of the upper layer liquid 6 flowing out from the phase separation tank 11 so as to produce a membrane filtration water 8.

Description

  The present invention relates to a water treatment apparatus for producing fresh water from water to be treated such as seawater and brine.

  Various methods for producing fresh water from seawater using a semipermeable membrane are known, but a reverse osmosis method for forcibly permeating water by applying a pressure higher than the osmotic pressure to seawater has been mainly developed. However, since this method needs to be pressurized to a high pressure, there is a problem that the equipment cost and the operation cost are high. Therefore, seawater and salt solution with a higher concentration than seawater are brought into contact with each other through a semipermeable membrane, and water in seawater is transferred to this salt solution by osmotic pressure without being pressurized, and separated and recovered to produce fresh water. A method has been developed. (Patent Documents 1 and 2).

  In the method of Patent Document 1, a salt solution obtained by dissolving ammonia and carbon dioxide is passed through a semipermeable membrane on the side opposite to seawater, and water in the seawater is passed through the semipermeable membrane into the salt solution. From the diluted salt solution obtained, the ammonium ions and carbonate ions are separated separately using an ion exchange membrane, a distillation tower, etc. to obtain purified water, and the separated ammonium ions and carbonate ions are dissolved in the salt solution. This is a method of returning to the original room of the semipermeable membrane treatment apparatus.

  The method of Patent Document 2 uses an attracting solution in which a temperature-sensitive drug having a cloud point is used as a solute, and as shown in FIG. 9, seawater 21 is sent to a forward osmosis system 30 where it passes through a semipermeable membrane. Then, it is brought into contact with the attracting solution 24, and the water in the seawater 21 is transferred to the attracting solution 24 through the semipermeable membrane by osmotic pressure. The concentrated seawater 22 remaining after the water has moved to the attracting solution flows out of the forward osmosis system 30. On the other hand, the diluted attraction solution 25 diluted with water in seawater is sent to a precipitation system 34 equipped with a heater, and the diluted attraction solution that has undergone phase separation or precipitation is pressurized by a pump 37 to the filtration system 32. Sent. At that time, a liquid 29 having a temperature lower than the cloud point of the solute can be added. The attraction solution 24 concentrated in the filtration system 32 is returned to the forward osmosis system 30. On the other hand, the filtered membrane filtrate 28 is further purified by the post-processing unit 33 to become drinking water. Polyethylene glycol or polypropylene glycol is used as a temperature-sensitive drug having a cloud point, and a nanofiltration membrane or a reverse osmosis membrane is used as a filter medium of a filtration system.

JP 2011-83663 A U.S. Pat. No. 8.021.553 B2

In the method of Patent Document 1, the attracting substance (for example, ammonium carbonate) is separated and recovered by an evaporation method. At that time, the latent heat of vaporization of ammonia and accompanying water is great, enormous energy is required, and the cost is high. Furthermore, the size of the evaporation facility is extremely large, and is not suitable for producing a large amount (for example, 100,000 m ³ / day) of drinking water. Moreover, since the input energy is large, the size of the heat exchanger is also large, which is not suitable for mass processing. Furthermore, when ammonium carbonate is used, the attracting substance that leaks into the environment through the membrane concentrated water by backflow from the semipermeable membrane contains nitrogen, which causes eutrophication.

  The method of patent document 2 can reduce membrane filtration energy by aggregating a part of attractant using the temperature sensitivity of an attractant solution. In this method, the diluted attracting solution in which the attracting substance is aggregated is sent to the filtration system as it is to separate the aggregate by filtration. However, since the droplets aggregated at a temperature equal to or higher than the cloud point temperature are very fine, a great amount of time and energy are required for filtration and separation.

  As a means for solving this problem, the present inventor does not send the diluted attraction solution in which the attracting substance is aggregated to the filtration system as it is, but once mainly uses the attracting substance which is a temperature-sensitive drug in the phase separation tank. The lower layer liquid is separated into an upper layer liquid mainly composed of water, and the lower layer liquid is cooled to below the cloud point and circulated to the forward osmosis step as an attracting solution, and only the upper layer liquid is filtered through a nanofiltration membrane or the like. We are developing.

  Then, the present inventor further studied, and even if the dilution attraction solution heated to a temperature equal to or higher than the cloud point in the heating step was supplied to the phase separation tank, the temperature decreased in the phase separation tank and the amount of drug recovered Found that the decline.

  An object of the present invention is to more efficiently separate a temperature-sensitive drug that has been aggregated by heating in a method for producing fresh water by forward osmosis using a temperature-sensitive drug that has a cloud point and aggregates when heated as an attractant. It is to provide a method that can.

  In order to solve the above-mentioned problems, the present inventor, as a result of intensive studies, provided a heating means in the phase separation tank for performing phase separation of the dilution attraction solution to heat the dilution attraction solution in the tank, thereby concentrating the concentrated layer. The drug concentration of the lower layer liquid is higher, and the drug concentration of the upper layer liquid that is a dilute layer is lower, thereby preventing a decrease in the drug recovery rate in the phase separation tank.

  However, when heated in the tank, the agglomerated drug droplets float up due to thermal convection, and the fine drug droplets generated in the heating part of the upper layer part are collected as the upper layer liquid before settling. As a result, a decrease in the drug recovery rate was found. To solve this problem, an inclined plate is installed in the phase separation tank, and the chemical droplets that have risen due to thermal convection and the fine chemical droplets generated in the upper layer are combined and settled as large droplets. did.

  That is, the present invention brings the water to be treated into contact with an attraction solution in which a temperature sensitive drug is dissolved in water through a semipermeable membrane, and moves the water in the to-be-treated water to the attraction solution through the semipermeable membrane. A forward osmosis membrane treatment device for obtaining a diluted attraction solution diluted with water and membrane concentrated water, and a first for heating the diluted attraction solution flowing out from the forward osmosis membrane treatment device to a temperature equal to or higher than a cloud point of the attraction solution. And a phase separation tank for phase-separating the dilution attraction solution heated by the first heating means into a lower layer liquid having a high temperature-sensitive drug concentration and an upper layer liquid having a low temperature-sensitive drug concentration, A cooling means for cooling the lower layer liquid flowing out from the phase separation tank to a temperature below the cloud point of the attracting solution, and a membrane filtration device for membrane filtration of the upper layer liquid flowing out from the phase separation tank to obtain membrane filtered water A water treatment device having a second heating means and a tilt in the phase separation tank The there is provided a water treatment apparatus characterized by comprising.

  According to the present invention, in a water treatment apparatus using a forward osmosis method using a temperature sensitive drug having a cloud point, the temperature sensitive drug is efficiently separated from the upper layer liquid which is a dilute layer of the phase separated temperature sensitive drug. The filtration burden on the filtration device can be greatly reduced.

It is a block diagram which shows one embodiment of this invention typically. It is side surface sectional drawing of an example of a phase separation tank. It is the figure which looked at the downward direction from AA 'of FIG. It is the figure which looked at the downward direction from BB 'of FIG. It is the figure which looked at the right side from CC 'and DD' of FIG. It is a block diagram which shows another embodiment of this invention typically. It is a schematic longitudinal cross-sectional view of an example of a coalescer. 3 is a curve showing the relationship between cloud point temperature and drug concentration. It is a block diagram which shows the outline of a well-known water treatment method.

  FIG. 1 schematically shows an embodiment of the present invention.

  The water to be treated to be treated by the apparatus of the present invention is a solution using water as a solvent, such as seawater or brine. Brine includes associated water from wells that mine shale gas, oil sand, CBM (coal bed methane), oil, and the like.

Accompanying water is water that is discharged along with the object to be mined from the well, and includes salt, organic matter, suspended matter, and the like. Concentrations of pollutants include, for example, evaporation residues (mainly Na ⁺ , K ⁺ , Ca ²⁺ , Cl ⁻ , SO ₄ ^2−, etc.) of 1,000 to 100,000 mg / L, organic substances (such as oil and added chemicals) Is contained in a range of 10 to 1,000 mg / L as TOC and suspended material in a range of 100 to 10,000 mg / L.

  There is no limitation on the means for separating oil and associated water, but oil-water separation is performed, for example, by sedimentation.

Although not shown in FIG. 1, the water to be treated is first filtered if necessary. This filtration treatment is performed, for example, with a filter using a microfiltration membrane, and a normal membrane used as a microfiltration membrane can be used as the filtration membrane. For example, in addition to cellulose acetate, polytetrafluoroethylene, polysulfone, polyvinyl chloride, etc., a ceramic film or a porous glass film can be used. In the micromembrane filtration treatment, membrane filtrate water that has passed through the microfiltration membrane and membrane concentrated water remaining without passing through the membrane are obtained.
In addition to precision membrane filtration, filtration treatment such as ultramembrane filtration and sand filtration can be used. The material for the ultrafiltration is the same as that for precision membrane filtration.

Forward osmosis membrane treatment device The forward osmosis membrane treatment device brings the treated water that has been filtered into contact with a high osmotic pressure attraction solution in which a temperature-sensitive drug is dissolved in water through a semipermeable membrane. The apparatus moves water to the attracting solution through the semipermeable membrane to obtain a diluted attracting solution diluted with water and membrane concentrated water.

  The semipermeable membrane is preferably one that can selectively permeate water, and is preferably a forward osmosis membrane, but a reverse osmosis membrane can also be used. The material is not particularly limited, and examples thereof include cellulose acetate-based, polyamide-based, polyethyleneimine-based, polysulfone-based, and polybenzimidazole-based materials. The form of the semipermeable membrane is not particularly limited and may be any of a flat membrane, a tubular membrane, a hollow fiber, and the like.

  The forward osmosis membrane treatment apparatus to which this semipermeable membrane is attached usually has a semipermeable membrane installed in a cylindrical or box-shaped container, and water to be treated flows into one chamber partitioned by this semipermeable membrane, An attracting solution can be flowed into the other chamber, and a known semipermeable membrane device can be used, and a commercially available product can be used.

  A temperature-sensitive drug is a substance that is hydrophilic and well soluble in water at low temperatures, but becomes hydrophobic and decreases in solubility at a certain temperature or higher, and the temperature at which it changes from water-soluble to water-insoluble is called a cloud point. When this temperature is reached, the hydrophobized temperature-sensitive drug precipitates and white turbidity occurs.

  This temperature-sensitive agent is used as various surfactants, dispersants, emulsifiers, and the like. For example, alcohol or fatty acid and ethylene oxide compound, alcohol or fatty acid and propylene oxide compound, acrylamide and alkyl group Compounds, ethylene glycol fatty acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, ethylene oxide adducts, amino acids and derivatives thereof, preferably block copolymers of polyethylene glycol and polypropylene / polybutylene glycol, glycerol ethoxylate butoxylate, And trimethylolpropane ethoxybutoxylate. As the temperature sensitive agent used in the present invention, those having a cloud point in the range of 30 ° C to 80 ° C, particularly in the range of 40 ° C to 60 ° C are preferable. Therefore, the cloud point can be adjusted to the above range by combining a nonionic surfactant having an HLB value of 10 or more and a nonionic surfactant having a lower HLB value, a fatty acid or an alcohol.

  The concentration of the attracting solution must be adjusted so that the osmotic pressure of the attracting solution is sufficiently higher than the osmotic pressure of the liquid to be treated.

  Aggregating solid particles may be added to the attracting solution. As the solid particles for aggregation, bentonite, kaolin, activated carbon powder and the like can be used, and an inorganic adsorbent is more desirable. The average particle size is preferably about 0.1 to 10 μm. The amount of solid particles added is suitably about 0.1 to 10% by weight with respect to the temperature sensitive drug. However, these are preferably determined in consideration of the affinity between the temperature sensitive drug and the solid particles.

  When the water to be treated is brought into contact with the attracting solution through the semipermeable membrane in the forward osmosis membrane treatment apparatus, the water in the treated water moves to the attracting solution through the semipermeable membrane due to the difference in osmotic pressure.

The first heating means is means for warming the dilution attraction solution flowing out from the forward osmosis membrane treatment apparatus to a temperature equal to or higher than the cloud point and aggregating at least a part of the temperature sensitive drug as droplets. These agglomerated droplets are obtained by phase separation of a concentrated solution of a temperature sensitive drug.

  The heating means is only required to be heated to a predetermined temperature, and any device such as an electric heater or a heat exchanger can be used.

It is preferable to use the sensible heat of the lower layer liquid separated in the next phase separation tank as the heat source of the heating means.
Phase separation tank The phase separation tank is a tank for phase-separating the dilution attraction solution heated by the first heating means into a lower layer liquid having a high temperature sensitive drug concentration and an upper layer liquid having a low temperature sensitive drug concentration. . This phase separation can be performed by standing in a phase separation tank at a liquid temperature higher than the cloud point. At that time, the concentrated solution of the temperature-sensitive drug aggregated by the first heating means is in the form of fine droplets with the aggregation solid particles as a core. And if it puts into a phase-separation tank in this state, the fine droplet of a concentrated solution will settle quickly, and droplets will unite and a dense layer will be formed underneath. Most of the solid particles for agglomeration collect in the dense layer, but only a small part remains in the upper dilute layer. The time required for this layering is about 2 to 4 hours in the absence of agglomerating solid particles, but it is about 0.5 to 1.0 hours (about one quarter) by the presence of this. It can be shortened.

  By the way, the present inventor provides a second heating means in this phase separation tank to heat the dilution attraction solution in the tank, thereby increasing the concentration of the lower layer solution, which is a concentrated layer, to be a dilute layer. Although the drug concentration in the upper layer liquid can be lowered, the drug droplets aggregated by heat convection due to heating in the tank rise, and before the drug droplets generated in the heating part of the upper layer also settle It was found that it was separated as an upper layer liquid. Then, by providing an inclined plate in the phase separation tank, it was found that drug droplets that were raised by thermal convection and fine drug droplets that were generated in the upper layer could be combined into large droplets to increase the sedimentation speed. It was.

  A 2nd heating means is arrange | positioned so that both the upper layer part and lower layer part of the dilution attraction solution in a phase separation tank can be heated. The heating means can be any one such as an electric heater or a heat exchanger, but the tubular and plate-like ones are arranged as evenly as possible so as to uniformly heat the dilution-inducing solution in the upper and lower layers. Is good. The heating ability may be increased by about 1 to 5 ° C., preferably about 2 to 4 ° C., in the residence time of the phase separation tank in the dilution attraction solution.

  Inclined plates are the ones that cause the fine droplets in the lower layer liquid that has risen due to thermal convection and the fine droplets in the upper layer liquid generated by heating to adhere to the plate, coalesce into large particles, and settle. Provided near the top of the upper liquid and near the liquid surface. Usually, a plurality of sheets, about 2 to 20 sheets, preferably about 4 to 10 sheets, may be provided in parallel, and the projected area from the top is 50% or more, preferably 100% or more of the liquid surface. Install to cover. The tilt angle is preferably tilted in the same direction as the flow direction of the upper layer liquid, and the angle may be about 0 to 90 °, preferably about 15 to 45 °.

Cooling means The lower layer liquid separated in the phase separation tank is cooled to a temperature lower than the cloud point of the attracting solution, so that the temperature sensitive drug is dissolved in water and regenerated into the attracting solution. Although this temperature can be employed in a wide range, considering the economy, a temperature of room temperature or higher is preferable. As this cooling heat source, it is preferable from the viewpoint of efficient use of energy to use the water to be treated or the dilution attraction solution obtained in the forward osmosis membrane treatment apparatus. If this cooling is insufficient, the concentration is lowered by the water moving from the water to be treated in the forward osmosis membrane treatment apparatus, so that a cloud point is developed and the phases are separated and the osmotic pressure is lowered.

  The regenerated attractant solution can be recycled as it is.

In the present invention, as described above, the separation efficiency can be increased by providing the second heating means and the inclined plate in the phase separation tank. However, the upper layer liquid separated in the phase separation tank contains 1 to 5% by weight, usually 2 to 3% by weight, of the temperature sensitive drug, which considerably increases the filtration load in the membrane filtration device. It is preferable to reduce the temperature sensitive drug before sending the upper layer liquid to the membrane filtration device. However, since the temperature-sensitive drug contained in the upper layer liquid is extremely fine particles, the separation thereof is not easy. As a result of various studies on the separation means, the present inventor has found that separation can be performed very efficiently by using a coalescer. The coalescer is an aqueous solution containing hydrophobic droplets that passes through the filter, attaches the hydrophobic droplets to the filtration medium and entangles them, forcibly coalesces them, coarsens them, and separates them. This separation can usually be performed by specific gravity separation. The filtration medium is made of fluororesin, other various resins, alumina fibers, glass fibers, and the like, and there are patent applications such as JP 2000-508581 and JP 2012-200682. Moreover, it is marketed with brand names, such as "Phase Cep HE series" (Nippon Pole Co., Ltd., Pole Industrial Company), and "Utec" (Asahi Kasei Fibers Co., Ltd.).

  The coalescer is a main body cartridge accommodated in a tank, and there are a vertical type and a horizontal type. In both cases, the inlet side of the liquid to be separated is partitioned and allowed to flow into the cartridge, and the liquid that has passed through the cartridge separates the hydrophobic droplets grown at that time from the water phase in the tank with a specific gravity. The other is extracted from the upper part from the lower part. An example of a vertical coalescer is shown in FIG. This coalescer is provided with a bottom plate 172 that partitions the bottom of a cylindrical tank 171 and a cartridge 173 that is the main body of the coalescer is vertically provided above the central passage. A temperature-sensitive drug outlet 174 is provided immediately above the bottom plate 172, and an upper-layer liquid outlet 175 from which the temperature-sensitive drug has been removed is provided above the tank 171. The upper layer liquid 6 containing the temperature sensitive drug enters from the bottom inlet 176 of the tank 171 and passes through the cartridge 173. At that time, the temperature sensitive drug droplets adhere to the filter medium and become entangled, and the droplets coalesce. It becomes coarse and is discharged into the tank chamber. The discharged temperature-sensitive drug droplets settle and further coalesce, and are taken out from the temperature-sensitive drug outlet 174 at the bottom of the tank chamber. On the other hand, the upper layer liquid from which the temperature-sensitive drug droplets are collected and separated flows out from the upper layer liquid outlet 175 at the upper part of the tank.

  By this coalescer treatment, about 50 to 80% of the temperature sensitive drug contained in the upper layer liquid is removed, and the concentration becomes less than 2% by weight.

  In addition, when the phase separation tank with a residence time of about 0.5 to 1.0 hour is downsized (residence time of 10 to 20 minutes), the droplet settling rate is smaller than the surface load of the phase separation tank. Since it increases, the temperature-sensitive drug concentration of the upper layer liquid becomes a high concentration of 5 to 7% by weight. By treating this with a coalescer, the concentration of the upper layer liquid became less than 2% by weight. Thus, the phase separation tank can be downsized by introducing the coalescer process.

Membrane filtration device On the other hand, the upper layer liquid separated by the phase separation tank or further having the temperature-sensitive agent removed by the coalescer is subjected to membrane filtration with a nanofiltration membrane or a reverse osmosis membrane, and the temperature remaining there Remove sensitive drugs and solid particles for aggregation. Membrane filtrate is fresh water and can be used for drinking water and the like. The membrane concentrated water remaining without being membrane filtered contains a temperature sensitive drug and solid particles for agglomeration, and therefore should be circulated to the phase separation tank. Alternatively, it can be concentrated and returned directly to the forward osmosis membrane treatment apparatus as an attracting solution.

  On the other hand, since the membrane concentrated water obtained by the forward osmosis membrane treatment apparatus contains a high concentration of salt, it can be concentrated by depositing the salt to separate it for effective use.

  An example of the apparatus of the present invention is schematically shown in FIG. As shown in the figure, water 1 to be treated such as seawater is fed into a forward osmosis membrane treatment apparatus 10, and water is permeated through the semipermeable membrane 3 to the opposite chamber and the remaining membrane concentrated water 2 is discharged. The The attracting solution 4 flows into the chamber on the opposite side of the forward osmosis membrane treatment apparatus 10, and is diluted with water transferred from the treatment water 1 in countercurrent contact with the treatment water 1 through the semipermeable membrane 3. Then, the forward osmosis membrane treatment apparatus 10 is exited. The dilution attraction solution 5 exiting the forward osmosis membrane treatment apparatus 10 is heated by heat exchange with the lower layer liquid 7 phase-separated by the heat exchanger 16, and further heated by the heater 14 to the phase separation tank 11. enter.

  As schematically shown in the upper right of FIG. 1, the phase separation tank 11 is provided with a heater 111 and an inclined plate 112 therein. The heater 111 is disposed so as to heat both the upper layer liquid and the lower layer liquid in the phase separation tank 11, and the inclined plate 112 is disposed so as to be inclined in the same direction as the outflow direction of the upper layer liquid.

  The upper layer liquid 6 separated in the phase separation tank 11 is filtered by a membrane filtration device 12, and the obtained membrane filtrate 8 is further purified by an aftertreatment device 13 such as activated carbon to obtain purified water. The membrane concentrated water 9 that has not been filtered by the membrane filtration device 12 is returned to the phase separation tank 11 and phase-separated together with the dilution attraction solution.

  On the other hand, the lower layer liquid 7 separated in the phase separation tank 11 is cooled by the cooler 15 through the heat exchanger 16 and returned to the forward osmosis membrane treatment apparatus 10 as the attraction solution 4.

  Another example of the apparatus of the present invention is shown in FIG. This apparatus is the same as the apparatus of FIG. 1 except that a coalescer 17 is provided between the outlet of the upper layer liquid 6 of the phase separation layer 11 and the membrane filtration device 12. The upper layer liquid from which the temperature sensitive drug is separated by the coalescer 17 is sent to the membrane filtration device 12, and the temperature sensitive drug separated by the coalescer 17 is returned to the phase separation tank 11.

  The apparatus shown in FIG. 1 was used. A cellulose acetate forward osmosis membrane was used as the semipermeable membrane of the forward osmosis membrane treatment device 10, and a nanofiltration membrane was used as the membrane filtration device 12.

  As the phase separation tank 11, the one shown in FIGS. This tank has a box shape and is 550 mm long, 1000 mm wide, and 700 mm deep. On the left side of FIG. 2, a dilute attracting solution inflow pipe is provided, and on the inner side of the tank, there is a rectifying plate so that the dilute attracting solution introduced spreads laterally from the bottom of the tank and enters the tank. It is provided perpendicular to the left wall of the tank. As shown in FIGS. 2 and 4, a tubular heater is provided in four stages on the inner side of the rectifying plate, and four inclined plates are provided on the right side of the drawing at an angle of 30 ° from the vertical. It has been. Each inclined plate has a projected area from above, a width of 130 mm, a length of 550 mm, and an interval of inclined plates of 20 mm. A thermometer is provided in the heater section. A lower layer liquid outlet that is a thick layer is provided in the lower part on the right side of the tank drawing, and an overflow overflow weir is provided in the upper part, and an outlet of the upper layer liquid that is a dilute layer that has overflowed there is in the overflow weir. Is provided.

  As the attracting solution, a solution obtained by adding water to a mixture of polyglycerin monolaurate and sorbitan monocaprylate to a drug concentration of 90% by weight was used. The cloud point of this solution was 60 ° C.

  This cloud point temperature varies depending on the drug concentration. FIG. 8 shows the results of examining the relationship between the drug concentration and the cloud point.

  Bentonite having an average particle size of 1 μm was suspended in the attracting solution by adding 1% by weight to the temperature-sensitive drug.

  Seawater pretreated with a UF membrane was treated as treated water 1 and allowed to flow into the forward osmosis membrane treatment apparatus 10 at a flow rate of 3 L / min. The amount of the membrane permeated water was 1.5 L / min, and the amount of the dilution attraction solution 5 flowing out from the forward osmosis membrane treatment apparatus 10 was 3.8 L / min. The dilution attraction solution 5 was heated to 60 ° C. by the heater 14 through the heat exchanger 16 and flowed into the phase separation tank 11. By further heating in the phase separation tank to 70 ° C., a larger amount of the drug became droplets. As a result of the droplets generated in the upper layer and the drug droplets raised by thermal convection being aggregated and effectively separated by the inclined plate, the temperature-sensitive drug concentration is 2 to 3% by weight for the diluted upper layer liquid, the dense lower layer The liquid was 90 to 93% by weight, which was lower than the dilute upper layer liquid concentration (5% by weight) assumed by phase separation at 60 ° C. and higher than the concentrated lower layer liquid concentration (90% by weight).

  The obtained lower layer liquid 7 was cooled to 40 ° C. by the cooler 15 through the heat exchanger 16 and again flowed into the forward osmosis membrane treatment apparatus 10. The upper layer liquid 6 was introduced into the membrane filtration device 12 and separated into membrane filtrate 8 and membrane concentrated water 9. The membrane concentrated water 9 was again flowed into the phase separation tank 11. Membrane filtrate 8 obtained fresh water of 1.5 L / min via post-treatment device 13. This fresh water could be used as drinking water.

  On the other hand, when no additional heating is performed in the phase separation tank, the liquid temperature is lowered in the phase separation tank, and the temperature-sensitive drug concentration is increased to 5 to 7% by weight in the diluted upper layer liquid. Was as low as 85 to 90% by weight.

  The method of the present invention can be widely used for production of fresh water from seawater, treatment of associated water from a well, and the like.

DESCRIPTION OF SYMBOLS 1 Water to be treated 2 Membrane concentrated water 3 Semipermeable membrane 4 Attraction solution 5 Dilution attraction solution 6 Upper layer liquid 7 Lower layer liquid 8 Membrane filtered water 9 Membrane concentrated water 10 Forward osmosis membrane treatment device 11 Phase separation tank 111 Heater (second addition Temperature means)
112 Inclined plate 12 Membrane filtration device 13 Post-processing device 14 Heater (first heating means)
15 Cooler (cooling means)
16 Heat exchanger (cooling means)
17 Coalesser 171 Tank 172 Bottom plate 173 Cartridge 174 Temperature sensitive drug outlet 175 Upper liquid outlet 176 Upper liquid inlet

Claims (5)

  The water to be treated was brought into contact with an attraction solution in which a temperature sensitive drug was dissolved in water through a semipermeable membrane, and the water in the water to be treated was transferred to the attraction solution through the semipermeable membrane and diluted with water. A forward osmosis membrane treatment device for obtaining a diluted attraction solution and membrane concentrated water, and a first heating means for heating the diluted attraction solution flowing out of the forward osmosis membrane treatment device to a temperature equal to or higher than a cloud point of the attraction solution; From the phase separation tank, a phase separation tank for phase-separating the dilution attraction solution heated by the first heating means into a lower layer liquid having a high temperature-sensitive drug concentration and an upper layer liquid having a low temperature-sensitive drug concentration; A water treatment device having a cooling means for cooling the lower layer liquid flowing out to a temperature below the cloud point of the attracting solution, and a membrane filtration apparatus for filtering the upper layer liquid flowing out from the phase separation tank to obtain membrane filtered water. A second heating means and an inclined plate are provided in the phase separation tank. Water treatment device that.   The water treatment apparatus according to claim 1, further comprising a coalescer that aggregates and separates a fine temperature-sensitive drug in the upper layer liquid flowing out of the phase separation tank in front of the membrane filtration apparatus.   The water treatment apparatus according to claim 1 or 2, further comprising a circulation means for circulating the membrane concentrated water flowing out from the membrane filtration apparatus to the phase separation tank.   The water treatment apparatus according to any one of claims 1 to 3, wherein the clouding point of the attracting solution is in the range of 30 ° C to 80 ° C.   The water treatment apparatus according to any one of claims 1 to 4, further comprising a heat exchange means for the lower layer liquid flowing out from the phase separation tank and the dilution attraction solution.

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