JP6685960B2 - Water treatment system and working medium - Google Patents

Description

  Embodiments relate to water treatment systems and working media.

  When the solution having a low solute concentration and the solution having a high solute concentration are separated by the osmotic membrane, the solvent of the low concentration solution permeates the osmotic membrane and moves to the high concentration solution side. It is known that a desalination system for desalination such as seawater desalination and an osmotic pressure power generation system for rotating a turbine to generate electricity by utilizing the phenomenon that the solvent moves. Further, a concentration system for concentrating food and sludge using this is also known. At this time, a working medium (draw solution) is used on the high-concentration side, and various types have been proposed so far.

  As the solute of the draw solution, salt is generally used. Organic salts are also used as solutes in draw solutions. However, the draw flux of the organic salt is inferior to the draw solution of the salt in permeation flux of water.

  A draw solution in which two or more solutes are mixed has been proposed. A mixture of a plurality of inorganic salts is observed to have a synergistic effect, but in the case of the inorganic salt and sucrose, the flux passing through the osmotic membrane may be reduced due to the adverse effect.

Japanese Patent Publication No. 2010-509540

  Embodiments provide a water treatment system and a working medium that can separate water at low cost.

A water treatment system according to an embodiment includes a first treatment container including a permeable membrane that partitions a first chamber that stores water to be treated and a second chamber that stores a working medium that induces an osmotic pressure. Is a compound having an ammonium salt structure of a phosphonic acid group in the main chain, a side chain, or a main chain and a side chain, or a compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain see contains as a solute, the main chain, side chain, or a compound in the main chain and side chains having a metal salt structure of phosphonic acid group, a phosphonic compound having the structure represented by formula (1), or (2) The acid group is a compound having a metal salt structure, and X ¹ , X ² and X ^{3 in} the formula (1) are H, — (CH ₂ ) _m1 PO (OH) ₂ (m ₁ is an integer of 1 to 3 ) . One or more selected from the group consisting of ^{Y 1} and ^Y 2 of 2), _OH, CH 3, Cl, an aqueous solution is at least one selected from the group consisting of Br and _CH 2 _CH 2 NH _2.

Schematic of the water treatment system which concerns on embodiment. The chemical formula of the solute according to the embodiment. Schematic of the water treatment system which concerns on embodiment. Schematic of the water treatment system which concerns on embodiment. Schematic of the water treatment system which concerns on embodiment.

Hereinafter, the water treatment system of the embodiment and a working medium used in the water treatment system will be described.
(First embodiment)
The water treatment system according to the first embodiment will be described with reference to the schematic diagram shown in FIG. The water treatment system 100 according to the first embodiment shown in FIG. 1 includes a permeable membrane 12 that divides a first chamber 13 that contains water to be treated A and a second chamber 14 that contains a working medium B. In the osmotic pressure generator 1 having the container 11, the working medium B induces an osmotic pressure.

  According to such a water treatment system 100, in the treated water A in the first chamber 13 due to the osmotic pressure difference generated between the treated water A in the first chamber 13 and the working medium B in the second chamber 14. Water C permeates the permeable membrane 12 and moves to the working medium B in the second chamber 14.

  By using the working medium B of the embodiment, the water C in the water to be treated A in the first chamber 13 permeates the permeation membrane with a large permeation flux and is moved to the working medium B in the second chamber 14. The water treatment system according to the embodiment is preferable because The working medium B of the embodiment is used for a water treatment system that can be operated at low cost, and a water treatment system.

  The first processing container 11 is divided into a first chamber 13 and a second chamber 14 by a permeable membrane 12. The first treatment container 11 is a resin or metal container that stores the water to be treated A in the first chamber 13 and the working medium B in the second chamber 14.

  The osmotic membrane 12 may be, for example, a forward osmosis membrane (FO membrane) or a reverse osmosis membrane (RO membrane). A preferred permeable membrane is a FO membrane.

  As the permeation membrane 12, for example, a cellulose acetate membrane, a polyamide membrane or the like can be used. The permeable membrane preferably has a thickness of 45 μm or more and 250 μm or less.

  The first chamber 13 is an area within the first processing container 11 that contains the water to be treated A, and is partitioned by the permeable membrane 12. The first chamber 13 may be provided with an introduction / exhaust path (not shown) through which the water A to be treated is introduced / exhausted.

  The water A to be treated is a liquid having a lower solute concentration than the working medium. Examples of the water A to be treated include salt water (sea water etc.), lake water, river water, swamp water, domestic waste water, industrial waste water, or a mixture thereof. When the water A to be treated is salt water, the salt (sodium chloride) concentration of the salt water may be, for example, 0.05% to 8%. The water A to be treated contains salts such as sodium chloride, magnesium chloride, magnesium sulfate, calcium sulfate, potassium chloride and floating substances, and concentrates other than water.

  The second chamber 14 is an area within the first processing container 11 that contains the working medium B, and is partitioned by the permeable membrane 12. The second chamber 13 may be provided with an introduction / exhaust path (not shown) through which the working medium B is introduced / exhausted.

The working medium B according to the first embodiment is a compound having a main chain, a side chain, or a metal salt structure of a phosphonic acid group in the main chain and the side chain, a main chain, a side chain, or a phosphonic acid group in the main chain and the side chain. And a compound having an ammonium salt structure of 1. as a solute. Since the working medium B is an aqueous solution, it contains water as a solvent. The working medium 14 containing such a solute is preferable because it exhibits a high osmotic pressure inducing action. Therefore, when the water in the water A to be treated in the first chamber 11 permeates the permeable membrane 15 and moves to the working medium B in the second chamber 13, a high permeation flux (Jw L / m ² h) Can be generated.

  Therefore, in the embodiment, it is possible to provide a water treatment system that can efficiently perform treatments such as desalting and concentration of the water A to be treated and that can be operated at low cost. It is also preferable that the water treatment system of the embodiment further includes a rotating body, and a water flow is generated by the induction of osmotic pressure, and the rotating body is rotated by the water flow to generate electricity.

  There is a phenomenon that the solute contained in the working medium B leaks out to the treated water A side through the osmosis membrane, and the loss of this solute causes the water quality of the treated water A to deteriorate, and further increases the running cost of the forward osmosis system. Let Such a phenomenon is likely to occur in a low molecular weight solute. With a high molecular weight solute, reverse permeation of the osmotic membrane 12 is unlikely to occur, but since the solubility in water is low and the concentration in the high molecular weight working medium B is low, it is difficult to achieve a high permeation flow rate.

It was found that if the solute compound contained in the working medium B contains a plurality of phosphonic acid groups (metal salt, ammonium salt), the solute reverse permeation flow rate (Js mmol / m ² h) can be reduced. This is the same even for low-molecular solutes, and the inclusion of a plurality of phosphonic acid groups (metal salt, ammonium salt) is preferable because solute loss is reduced.

Main chain of the embodiment, a side chain, or a compound having a metal salt structure of a phosphonic acid group on the main chain and a side chain and a compound having an ammonium salt structure of a phosphonic acid group on the main chain, a side chain, or the main chain and a side chain (molecules) _is represented by _{C x H y P z O w} N r Cl s Br t M u. M is a metal. In order to increase the permeation flow velocity, 2 ≦ x ≦ 9, 8 ≦ y ≦ 28, 1 ≦ z ≦ 6, 3 ≦ w ≦ 18, 0 ≦ r ≦ 3, 0 ≦ s ≦ 1, 0 ≦ t ≦ 1, 2 It is preferable to satisfy ≦ u ≦ 10. Further, in order to reduce the reverse solute permeation flow rate, 2 ≦ x ≦ 15, 8 ≦ y ≦ 35, 2 ≦ z ≦ 5, 7 ≦ w ≦ 15, 0 ≦ r ≦ 5, 0 ≦ s ≦ 1, 0 ≦ t. It is preferable to satisfy ≦ 1, 2 ≦ u ≦ 10. Then, in order to increase the permeation flow rate and decrease the solute reverse permeation flow rate, 2 ≦ x ≦ 9, 8 ≦ y ≦ 28, 2 ≦ z ≦ 5, 7 ≦ w ≦ 15, 0 ≦ r ≦ 3, 0 ≦ It is preferable that s ≦ 1, 0 ≦ t ≦ 1, and 2 ≦ u ≦ 10 are satisfied. The metal represented by M is a metal of a metal salt of phosphonic acid. The metal of the metal salt is preferably an alkali metal or an alkaline earth metal. The metal of the metal salt is preferably one or more selected from the group consisting of Na, K, Ca, Al and Mg. The element or structure contained in the solute of the embodiment can be determined by liquid chromatography to separate the compounds of the respective peaks, and NMR or an organic elemental analyzer.

  Main chain, side chain, or main chain and side chain of working medium B, and main chain, side chain, or compound having ammonium salt structure of phosphonic acid group on main chain and side chain and main chain, side chain, or main chain The chemical formula of the solute according to the embodiment of the compound having a metal salt structure of phosphonic acid group in the side chain is shown in FIG. It is preferable that the phosphonic acid group of the compound having the structure represented by the formulas (1), (2), and (3) in FIG. 2 is a metal salt structure or the phosphonic acid group has an ammonium salt structure. In the case of a metal salt, some or all of the phosphonic acid groups are metal salts of phosphonic acid groups. If it is an ammonium salt, some or all of the phosphonic acid groups are ammonium salts of phosphonic acid groups. A part of the side chain contained in the solute compound may contain a phosphonic acid group which is not a salt.

X ¹ , X ² and X ³ in the formula (1) are one or more selected from the group consisting of H, — (CH ₂ ) _m1 PO (OH) ₂ (m ₁ is any integer from 1 to 3). Is. Two or more of X ¹ , X ² and X ³ are preferably — (CH ₂ ) _m1 PO (OH) ₂ (m ₁ is any integer of 1 to 3) because solute loss is small. As the compound having the structure represented by the formula (1) in FIG. 2, nitrotris (methylenephosphonic acid) is preferable. As the compound in which the phosphonic acid group of the compound having the structure represented by the formula (1) in FIG. 2 has a metal salt structure, nitrotris (methylenephosphonic acid) sodium salt and nitrotris (methylenephosphonic acid) potassium salt are Can be mentioned. Examples of the compound having a structure represented by the formula (1) in FIG. 2 in which the phosphonic acid group has an ammonium salt structure include nitrotris (methylenephosphonic acid) ammonium salt.

Y ¹ and Y ^{2 in} the formula (2) are one or more selected from the group consisting of OH, CH ₃ , Cl, Br and CH ₂ CH ₂ NH ₂ . As the compound having the structure represented by the formula (2) in FIG. 2, etidronic acid is preferable. Examples of the compound having a metal salt structure in which the phosphonic acid group of the compound having the structure represented by the formula (2) in FIG. 2 include etidronate sodium salt and etidronate potassium salt. Examples of the compound having a structure represented by the formula (2) in FIG. 2 in which the phosphonic acid group has an ammonium salt structure include ammonium etidronate.

^{Z 1,} Z 2, ^{Z 3} and ^{Z 4} _{are, H,} of formula _{(3) - (CH 2)} m2 PO (OH) 2 (m 2 is any one of 1 to 3 integer), - _(CH 2) in _{m3 N ((CH 2) m4} PO (OH) 2) 2 (m 3 is any one of 1 to 3 integers, _{m 4} is any one of 1 to 3 integer) one or more members selected from the group consisting of is there. N in the formula (3) of FIG. 2 is an integer of 2 or more and 10 or less. As the compound having the structure represented by the formula (3) in FIG. 2, ethylenediaminetetramethylenephosphonic acid and diethylenetriaminepentamethylenephosphonic acid are preferable. As the compound having a metal salt structure in the phosphonic acid group of the compound having the structure represented by the formula (3) in FIG. 2, ethylenediaminetetramethylenephosphonic acid sodium salt, diethylenetriaminepentamethylenephosphonic acid sodium salt, ethylenediaminetetramethyl Examples include methylenephosphonic acid potassium salt and diethylenetriamine pentamethylenephosphonic acid potassium salt. As the compound in which the phosphonic acid group of the compound having the structure represented by the formula (3) in FIG. 2 has an ammonium salt structure, ethylenediaminetetramethylenephosphonic acid ammonium salt and diethylenetriaminepentamethylenephosphonic acid ammonium salt ammonium salt are Can be mentioned.

  Therefore, a compound having a metal salt structure of a main chain, a side chain, or a phosphonic acid group in the main chain and a side chain includes etidronate sodium salt, etidronate potassium salt, nitrotris (methylenephosphonic acid) sodium salt, and nitrotris (methylenephosphone). Acid) potassium salt, ethylenediaminetetramethylenephosphonic acid sodium salt, diethylenetriaminepentamethylenephosphonic acid sodium salt, ethylenediaminetetramethylenephosphonic acid potassium salt and diethylenetriaminepentamethylenephosphonic acid potassium salt, at least one selected from the group consisting of Is preferred.

  Therefore, a compound having an ammonium salt structure of a phosphonic acid group in the main chain, a side chain, or a main chain and a side chain is an ammonium salt of etidronate, a nitrotris (methylenephosphonic acid) ammonium salt, an ethylenediaminetetramethylenephosphonic acid ammonium salt and a diethylenetriamine. It is preferable to be at least one selected from the group consisting of ammonium pentamethylenephosphonate.

  The substitution number of the alkali metal salt or ammonium salt changes depending on pH. For example, the 2Na salt of etidronic acid is weakly acidic and the 4Na salt is alkaline. From the viewpoint of the resistance of the FO film, it is desirable to use the working medium B in the vicinity of neutrality, but from the viewpoint of osmotic pressure, it is preferable that the number of substitutions is large. Therefore, the pH of the working medium B of the embodiment is preferably 2 or more and 10 or less. The pH of the working medium B is determined by measuring with a glass electrode type hydrogen ion concentration meter manufactured by Horiba by the method described in the manual.

  A compound having a metal salt structure of a main chain, a side chain, or a main chain and a phosphonic acid group in the main chain and a side chain, which is a solute in the working medium B, and an ammonium of a phosphonic acid group in the main chain, the side chain, or the main chain and the side chain. It is desirable to adjust the concentration of the compound having a salt structure based on the concentration of solute in the water A to be treated, the type of solute, and the characteristics of the solute. Usually, a compound having a metal salt structure of a main chain, a side chain, or a main chain and a side chain and a phosphonic acid group in the working medium B and a main chain, a side chain, or a phosphonic acid group in the main chain and the side chain. The concentration of the compound having an ammonium salt structure is 10% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 70% by mass or less, and most preferably 50% by mass or more and mass% or less. However, if inconvenience occurs, such as when the viscosity increases, the concentration should be adjusted downward. The upper limit of concentration depends on the solubility of the substance.

(Second embodiment)
Next, a desalination system which is an example of the water treatment system will be described with reference to the schematic diagram shown in FIG. In the second embodiment, the first chamber 13, the water to be treated A, the second chamber 14, the working medium B and the permeable membrane 12 are common to the first embodiment. The water A to be treated is salt water (aqueous sodium chloride solution) such as seawater. The working medium B used in the second embodiment is the working medium B of the first embodiment. In FIG. 3 and subsequent figures, the symbols of the water to be treated, the working medium and the water in the water treatment system are not shown, but these symbols are common to the water treatment system of FIG. 1.

  The desalination system 200 includes an osmotic pressure generator 1, a dilution working medium tank 2, a reverse osmosis membrane separator 3, and a concentration working medium tank 4. The osmotic pressure generator 1, the diluting working medium tank 2, the reverse osmosis membrane separation section 3, and the concentrating working medium tank 4 are connected in this order to form a loop. The working medium B (draw solution) that induces the osmotic pressure circulates in this loop. That is, the working medium B circulates through the osmotic pressure generator 1, the diluting working medium tank 2, the reverse osmosis membrane separator 3 and the concentrating working medium tank 4 in this order. The top and bottom are the directions shown in the drawings, for example, the concentrated working medium tank 4 is on the upper side of the dilution working medium tank 2, and the osmotic pressure generator 1 is on the left side of the reverse osmosis membrane separator 3. It is in.

  The treated water tank 15 is connected to the upper portion of the treatment container 10 in which the first chamber 13 is located through a pipeline 101a. The first pump 16 is provided in the pipeline 101a. The pipeline 101b for discharging the concentrated water A to be treated is connected to the lower portion of the first treatment container 11 in which the first chamber 13 is located.

  The reverse osmosis membrane separation unit 3 includes, for example, an airtight second processing container 21. The second processing container 21 is horizontally partitioned, for example, by a reverse osmosis membrane (RO membrane) 22, and a third chamber 23 is formed on the left side and a fourth chamber 24 is formed on the right side.

  The dilution work medium tank 2 is connected to the lower portion of the second processing container 21 in which the third chamber 23 is located, through a pipeline 101e. The third pump 25 is provided in the pipeline 101e. The upper portion of the second processing container 21 in which the third chamber 23 is located is connected to the concentration working medium tank 4 through the pipeline 101f. The lower portion of the second processing container 21 in which the fourth chamber 24 is located is connected to the pure water tank 26 through the pipeline 101g. The pure water tank 26 stores water (fresh water) that has moved to the fourth chamber through the reverse osmosis membrane 22 when the working medium B is concentrated. To the pure water tank 26, a pipeline 101h for connecting the pure water in the pure water tank 26 to the outside and collecting the pure water is connected. The on-off valve 27 is provided in the pipeline 101h. For example, when the pure water in the pure water tank 26 exceeds a certain amount, it is opened.

  The concentrated working medium tank 4 is connected to the upper part of the first processing container 11 in which the second chamber 13 is located through a pipeline 101c. The second pump 17 is provided in the pipeline 101a. The lower portion of the processing container 10 in which the second chamber 13 is located is connected to the dilution working medium tank 2 through the pipeline 101d.

  Next, a desalting operation by the desalination system 200 shown in FIG. 3 will be described.

  The first pump 16 is driven to supply the untreated water A (for example, seawater) from the untreated water tank 15 into the first chamber 13 of the osmotic pressure generator 1 through the pipeline 101a. Around the supply of seawater, the second pump 17 is driven to supply the concentrated working medium B from the concentrated working medium tank 4 into the second chamber 14 of the osmotic pressure generator 1 through the pipeline 101c. At this time, the solute concentration of the concentrated working medium B supplied to the second chamber 14 is higher than the salt concentration of the seawater supplied to the first chamber 13. Therefore, an osmotic pressure difference occurs between the seawater in the first chamber 13 and the concentrated working medium B in the second chamber 14, and the water in the seawater permeates the permeable membrane 12 and moves into the second chamber 14. . The concentrated working medium B in the second chamber 14 is an aqueous solution containing the solute of the first embodiment and exhibits a high osmotic pressure inducing action. Therefore, when the water in the seawater in the first chamber 13 permeates the permeation membrane 12 and moves to the concentrated working medium B in the second chamber 14, a high permeation flux is generated. As a result, a large amount of water in the seawater in the first chamber 13 can be moved to the concentrated working medium B in the second chamber 14, and a highly efficient desalination process for extracting water (pure water) from salt water can be executed.

  In the osmotic pressure generator 1, when water in seawater moves from the first chamber 13 to the concentrated working medium B in the second chamber 14, the seawater is discharged as concentrated seawater from the first chamber 13 through the pipeline 101b, The concentrated working medium B is diluted with the transferred water.

  The diluting work medium B in the second chamber 14 is sent to and stored in the diluting work medium tank 2 through the pipeline 101d. When the diluted working medium B is stored in the diluted working medium tank 2 up to a predetermined water level, the third pump 25 is driven to move the diluted working medium B in the diluted working medium tank 2 to the second treatment container of the reverse osmosis membrane separation unit 3. It is supplied to the third chamber 23 of No. 21 at a desired pressure through the pipeline 101e. The water in the dilution working medium B supplied to the third chamber 23 at a desired pressure is forcibly permeated through the reverse osmosis membrane (RO membrane) 22 and moves to the fourth chamber 24. The diluted working medium B in the third chamber 23 is concentrated by moving water to the fourth chamber 24. The concentrated working medium B is sent from the third chamber 23 to the concentrated working medium tank 4. The concentrated working medium B in the concentrated working medium tank 4 is supplied into the second chamber 14 of the osmotic pressure generator 1 by driving the second pump 17, and water (pure water) is taken out from the salt water as described above. Used for desalination treatment.

  On the other hand, the water (pure water) that has moved to the fourth chamber 24 is sent to the pure water tank 26 through the pipeline 101g. When the amount of water in the pure water tank 26 exceeds a certain amount, the opening / closing valve 27 is opened, and the water is sent to the outside through the pipeline 101h to collect the water.

  Therefore, it is possible to provide a desalination system that can efficiently perform desalination of seawater (recovery of pure water) and can be operated at low cost.

  In the desalination system 200 shown in FIG. 3, the osmotic pressure generator partitions the first processing container 11 in the horizontal direction by the osmotic membrane to form the first chamber 13 and the second chamber 14. The first chamber 13 and the second chamber 14 may be formed by partitioning the upper and lower parts with a permeable membrane.

  When the solute concentration of the working medium B decreases due to the desalting treatment, it is preferable to add the solute in the concentrated working medium tank 4 or the like.

  In the desalination system 200 shown in FIG. 3, the dilution working medium B is not limited to be concentrated in the reverse osmosis membrane separation unit including the reverse osmosis membrane (RO membrane), but may be any one that removes water in the dilution working medium B. Any device may be used.

(Third Embodiment)
Next, a concentration system 300, which is an example of a water treatment system, will be described with reference to the schematic diagram shown in FIG. The working medium B used in the third embodiment is the working medium B of the first embodiment.

  The concentration system 300 includes an osmotic pressure generator 31, a dilution working medium tank 32, a membrane distillation separator 33, and a concentration working medium tank 34. The osmotic pressure generator 31, the dilution working medium tank 32, the membrane distillation separator 33, and the concentration working medium tank 34 are connected in this order to form a loop. Working medium B (draw solution) circulates in this loop. That is, the working medium B circulates through the osmotic pressure generator 31, the dilution working medium tank 32, the membrane distillation separator 33, and the concentration working medium tank 34 in this order.

  The osmotic pressure generator 31 includes, for example, an airtight first processing container 41. The first processing container 41 is, for example, horizontally partitioned by an osmotic membrane 42 (for example, a normal osmotic membrane: FO membrane), and a first chamber 43 is formed on the left side and a second chamber 44 is formed on the right side. The treated water A, for example, a treated water tank 45 containing an undiluted solution such as industrial wastewater is connected to an upper portion of the first treatment container 41 where the first chamber 43 is located through a pipeline 201a. The first pump 46 is provided in the pipeline 201a. A pipeline 201b for discharging the concentrated stock solution in the first chamber 43 to the outside is connected to the lower portion of the first processing container 41 in which the first chamber 43 is located.

  The concentrated working medium tank 34 is connected to the upper portion of the first processing container 41 in which the second chamber 44 is located through a pipeline 201c. The second pump 47 is provided in the pipeline 201c. The lower portion of the first processing container 11 in which the second chamber 44 is located is connected to the dilution working medium tank 32 through the pipeline 201d.

  The membrane distillation separator 33 includes, for example, an airtight second processing container 51. The second processing container 51 is horizontally partitioned, for example, by a dehydration film 52 made of, for example, a porous latex film, and a third chamber 53 is formed on the left side and a fourth chamber 54 is formed on the right side.

  The diluting work medium tank 32 is connected to the lower portion of the second processing container 51 where the third chamber 53 is located through a pipeline 201e. The first opening / closing valve 61, the heat exchanger 62, and the third pump 63 are provided in the pipeline 201e in this order along the flow direction of the working medium B. A pipeline 201f of exhaust heat gas intersects the heat exchanger 62, and the working medium B flowing through the pipeline 201e exchanges heat with the exhaust heat gas to heat the working medium B. The upper portion of the second processing container 51 in which the third chamber 53 is located is connected to the upper portion of the circulation tank 64 through the pipeline 201g. The circulation tank 64 is connected to a portion of the pipeline 201e located between the first opening / closing valve 61 and the heat exchanger 62 through the pipeline 201h. The second opening / closing valve 65 is provided in the pipeline 201h.

  With such a configuration, a loop is formed by the third chamber 53 of the membrane distillation separator 33, the circulation tank 64, and the pipelines 201e, 201g, and 201h that connect these members. That is, the diluting work medium B dehydrated in the third chamber 53 described later and stored in the circulation tank 64 opens the second opening / closing valve 65 and drives the third pump 63, whereby the pipeline 201h and the pipeline 201e. , The third working chamber 53 and the pipeline 201g to form a diluting working medium circulation system. In the circulation of the dilution work medium B, the dilution work medium circulation system is isolated from the dilution work medium tank 32 by closing the first opening / closing valve 61.

  The circulation tank 64 is connected to the concentration work medium tank 34 through a pipeline 201i. The fourth pump 66 is provided in the pipeline 201i.

  The first pure water tank 71 is connected to the upper portion of the second processing container 51 in which the fourth chamber 54 is located through a pipeline 201j. The lower portion of the second processing container 51 in which the fourth chamber 54 is located is connected to the second pure water tank 72 through the pipeline 201k. The third opening / closing valve 73 is provided in the pipeline 201k and is closed when pure water is not circulated to retain pure water in the fourth chamber 54. The second pure water tank 72 is connected to the first pure water tank 71 through a pipeline 201m. The fifth pump 74 is provided in the pipeline 201m. With such a configuration, a loop is formed by the first pure water tank 71, the fourth chamber 54 of the membrane distillation separator 33, the second pure water tank 72, and the pipelines 201j, 201k, 201m connecting these members. That is, the pure water in the second pure water tank 72 opens the third opening / closing valve 73 and drives the fifth pump 74, so that the pipeline 201 m, the first pure water tank 71, the pipeline 201 j, and the fourth chamber 54. And a pure water circulation cooling system that circulates in the pipeline 201k.

  The second pure water tank 72 is connected to a pipeline 201n for sending the pure water in the second pure water tank 72 to the outside and collecting the pure water. The fourth opening / closing valve 75 is provided in the pipeline 201n. The fourth opening / closing valve 75 is closed when the pure water is circulated as described above, and is opened when the pure water in the second pure water tank 75 exceeds a certain amount.

  Next, the concentration operation by the concentration system 300 shown in FIG. 4 will be described.

  The first pump 46 is driven to supply an undiluted solution (for example, industrial wastewater) which is the untreated water A from the untreated water tank 45 into the first chamber 43 of the osmotic pressure generator 31 through the pipeline 201a. Before and after the supply of the stock solution, the second pump 47 is driven to supply the concentrated working medium B from the concentrated working medium tank 34 into the second chamber 44 of the osmotic pressure generator 31 through the pipeline 201c. The concentrated working medium B supplied to the second chamber 44 has a higher concentration than the concentration of the stock solution supplied to the first chamber 43. Therefore, an osmotic pressure difference occurs between the stock solution in the first chamber 43 and the concentrated working medium B in the second chamber 44, and the water in the stock solution permeates the osmotic membrane 42 and moves into the second chamber 44. . At this time, the concentrated working medium B in the second chamber 44 is an aqueous solution containing the solute of the embodiment and exhibits a high osmotic pressure inducing action. Therefore, when the water in the stock solution in the first chamber 43 permeates the permeable membrane 32 and moves to the working medium B in the second chamber 44, a high permeation flux is generated. As a result, a large amount of water in the stock solution in the first chamber 43 can be transferred to the working medium B in the second chamber 44, and the stock solution can be concentrated with high efficiency.

  In the osmotic pressure generator 31, the water in the stock solution moves from the first chamber 43 to the concentrated working medium B in the second chamber 44, so that the stock solution is discharged as a concentrated stock solution from the first chamber 43 through the pipeline 201b. Be recovered. The concentrated working medium B is diluted with the transferred water.

  The dilution work medium B in the second chamber 44 is sent to the dilution work medium tank 32 through the pipeline 201d and stored. When the dilution work medium B is stored in the dilution work medium tank 32 up to a predetermined amount, the first opening / closing valve 61 provided in the pipeline 201e is opened, the second opening / closing valve 65 provided in the pipeline 201h is closed, and the third The pump 63 is driven. As a result, the dilution working medium B in the dilution working medium tank 32 is supplied to the third chamber 53 of the second processing container 51 of the membrane distillation separator 33 through the pipeline 201e. While the diluted working medium B is supplied to the third chamber 53, the diluted working medium B flowing through the pipeline 201e exchanges heat with the exhaust heat gas flowing through the pipeline 201f at the heat exchanger 62 where the pipeline 201f intersects. Is heated. Further, the pure water in the second pure water tank 72 is opened by opening the third opening / closing valve 73 and driving the fifth pump 74, so that the pure water is supplied to the pipeline 201m, the first pure water tank 71, the pipeline 201j, and the It is circulated in the four chambers 54 and the pipeline 201k, and the dehydrated film 52 made of the porous latex film of the membrane distillation separator 33 is cooled with pure water from the fourth chamber 54 side. That is, the dehydrated film 52 on the fourth chamber 54 side is cooled by the pure water circulation cooling system.

  While supplying the pipeline 201e to the third chamber 53 of the membrane distillation separator 33 through the diluted working medium B thus heated, the dehydration membrane 52 of the membrane distillation separator 33 is replaced with pure water circulating in the fourth chamber 54. By cooling, the water in the diluting working medium B is evaporated in the third chamber 53, the vapor permeates the dehydration film 52 made of a porous latex film, moves to the fourth chamber 54, and circulates pure water. Are cooled, condensed, and taken into it. That is, the diluting work medium B is dehydrated in the third chamber 53. The dehydrated diluting working medium B in the third chamber 53 is sent to the circulation tank 64 through the pipeline 201g and stored therein. The dilution work medium B stored in the circulation tank 64 is concentrated to a certain concentration by the dehydration process.

  However, such a concentration is low in concentration and is not suitable for use as the above-mentioned concentration working medium B. Therefore, when a certain amount of the dehydrated diluted working medium B is stored in the circulation tank 64, the second opening / closing valve 65 is opened, and the dehydrated diluted working medium B in the tank 64 is transferred to the pipeline 201h. leak. At the same time, the first opening / closing valve 61 is closed to isolate the dilution working medium circulation system including the circulation tank 64, the pipeline 201h, the pipeline 201e, the third chamber 53 and the pipeline 201g from the dilution working medium tank 32.

  In such a dilution working medium circulation system and a pure water circulation cooling system, evaporation of water of the dilution working medium B in the third chamber 53 described above, permeation of vapor through the dehydration film 52, movement to the fourth chamber 54, By repeating the dehydration process of cooling and condensing with the circulating pure water on the fourth chamber 54 side a plurality of times, the concentration of the diluting working medium B can be increased so that it can be used as the concentrating working medium B. After the circulation and dehydration of the diluted working medium B, the second opening / closing valve 65 is closed to store the concentrated working medium B in the circulation tank 64. The water (pure water) that has moved to the fourth chamber 54 is sent out together with the pure water that circulates to the second pure water tank 72 through the pipeline 201k.

  After the concentrated working medium B having a concentration that can be used as the concentrated working medium B is stored in the circulation tank 64, the driving of the fifth pump 74 is stopped, the circulation of pure water to the fourth chamber 54 is stopped, and then the 3 The on-off valve 73 is closed. When the amount of pure water in the second pure water tank 72 exceeds a certain amount, the first open / close valve 75 is opened and sent out to the outside through the pipeline 201n to be collected.

  The fourth pump 64 is driven to send the concentrated working medium B in the circulation tank 64 to the concentrated working medium tank 34 through the pipeline 201i. The concentrated working medium B in the concentrated working medium tank 34 is supplied into the second chamber 44 of the osmotic pressure generator 31 by driving the second pump 47 for use in the concentration process of the stock solution as described above.

  Therefore, in the osmotic pressure generator 31, the stock solution is supplied to the first chamber 43, the concentration working medium B is supplied to the second chamber 44, and the water in the stock solution is concentrated from the first chamber 43 into the second chamber 44. The stock solution is moved to the medium B, concentrated, and discharged from the first chamber 43 through the pipeline 201b and collected. The concentrated working medium B is diluted with the moved water, and the diluted working medium B is sent to and stored in the diluted working medium tank 32.

  During the operation of concentrating the stock solution by the osmotic pressure generator 31, the diluted working medium B stored in the diluted working medium tank 32 includes a third working chamber 53 of the membrane distillation separator 33 and a membrane distillation separator 33. Concentration operation is performed by the pure water circulation cooling system including the fourth chamber 54, and the water (pure water) that has been sent to the concentration working medium tank 34 and moved to the fourth chamber 54 is sent and collected from the second pure water tank 72. To be done. That is, the concentration operation of the stock solution by the osmotic pressure generator 31 and the concentration of the diluted working medium B by the membrane distillation separator 33 can be continuously performed.

  Therefore, it is possible to provide the concentration system 300 that can efficiently perform the concentration treatment of the undiluted solution (water to be treated A) such as the industrial wastewater and the water recovery and can be operated at low cost.

  In the concentration system 300 shown in FIG. 4, the osmotic pressure generator horizontally partitions the first processing container 41 with the osmotic membrane to form the first chamber 43 and the second chamber 44. The first chamber 43 and the second chamber 44 may be divided into upper and lower parts by a permeable membrane.

  In the concentration system 300 shown in FIG. 4, the concentrated water to be treated A (for example, undiluted solution) in the first chamber 43 of the osmotic pressure generator 31 was sent to the outside through the pipeline 201b and collected, but it was concentrated to a higher concentration. To obtain the concentrated stock solution, the pipeline 201b is connected to the treated water tank 45 to form a loop of the treated water tank 45, the pipeline 201a, the first chamber 43 of the osmotic pressure generator 31, and the pipeline 201b. May be. In this case, it is desirable to determine the degree of concentration of the stock solution in consideration of the osmotic pressure difference between the concentrated stock solution in the osmotic pressure generator 31 and the concentrated working medium B.

  In the concentrating system 300 shown in FIG. 4, the dehydration membrane 52 of the membrane distillation separator 33 is not limited to the porous latex membrane, and may be any one having a vapor permeation function.

  In the concentration system 300 shown in FIG. 4, the dilution working medium B is not limited to be concentrated in the membrane distillation separator 33 having the dehydration membrane 52, but may be performed in any device as long as it removes water in the dilution working medium B. May be.

(Fourth Embodiment)
Next, a circulation type osmotic pressure power generation system 400, which is an example of the water treatment system according to the fourth embodiment, will be described with reference to the schematic diagram shown in FIG. In FIG. 5, the same members as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted. The working medium used in the fourth embodiment is the working medium B of the first embodiment.

  The water treatment system according to the fourth embodiment is a circulation type osmotic pressure power generation system. The circulatory osmotic pressure power generation system 400 includes an osmotic pressure generator 31 that generates a water flow, and a rotating body 82 that generates electric power using the water flow generated by the osmotic pressure generator 31.

  The circulation-type osmotic pressure power generation system 400 divides a first chamber 43 containing water, a second chamber 44 containing a working medium B (draw solution) that induces osmotic pressure, and a first chamber and a second chamber. The osmosis membrane 42, the pressure exchanger 81 connected to the second chamber 44, and the rotating body 82 connected to the pressure exchanger 81. According to such a water treatment system, the water in the first chamber 44 permeates the osmotic membrane 42 due to the osmotic pressure difference generated between the water in the first chamber 43 and the working medium B in the second chamber 44. It moves to the working medium B in the second chamber 44. The rotating body 82 is rotated by the water flow accompanying the movement of water to the working medium B to generate electricity.

  In the fourth embodiment, the working medium B is an aqueous solution containing the solute of the embodiment and exhibits a high osmotic pressure inducing action. Therefore, when the water in the first chamber 43 permeates the permeable membrane 42 and moves to the working medium B in the second chamber 44, a high permeation flux can be generated. As a result, the working medium B to which the water has been moved becomes a water flow having a high pressure, so that the rotating body 82 can be rotated at a higher speed to generate electricity. Therefore, it is possible to provide a water treatment system that can efficiently rotate the rotating body 82 to generate electricity and can be operated at low cost.

  As the rotating body 82, for example, a turbine or a water wheel can be used.

  The circulation type osmotic pressure power generation system 400 includes a pressure exchanger 81 and a rotation in the pipeline 201b connected to the lower portion (outlet side of the working medium B) of the first processing container 41 where the second chamber 44 of the osmotic pressure generator 31 is located. The body 82 is provided in this order along the flow direction of the working medium B. Further, in the pipeline 201c that connects the upper portion of the first processing container 41 in which the second chamber 44 is located and the concentrated working medium tank 34, the portion of the pipeline 201c downstream of the second pump 47 in the flow direction of the working medium B. Is connected to the upper part of the first processing container 41 where the second chamber 44 is located via the pressure exchanger 81. That is, in the osmotic pressure generator 31, the diluted working medium B having a flux generated when water permeates the osmotic membrane 42 from the first chamber 43 and moves to the second chamber 44, the second chamber 44 is located. It flows out from the lower part of the first processing container 41 through a pipeline 201b provided with a pressure exchanger 81. During this time, the pipeline 201c through which the concentrated working medium B flowing out of the concentrated working medium tank 34 passes through the pressure exchanger 81. Therefore, the concentrated working medium B is pressure-exchanged with the diluting working medium B flowing out of the second chamber 44 by the pressure exchanger 81, the diluting working medium B lowers in pressure, and the concentrated working medium B rises in pressure.

  In the circulating osmotic pressure power generation system 400, water is stored in the treated water tank 45.

Next, a power generation operation by the circulation type osmotic pressure power generation system 400 shown in FIG. 5 will be described.
The first pump 46 is driven to supply water from the treated water tank 45 into the first chamber 43 of the osmotic pressure generator 31 through the pipeline 201a. Before and after the supply of water, the second pump 47 is driven to supply the concentrated working medium B from the concentrated working medium tank 34 into the second chamber 44 of the osmotic pressure generator 31 through the pipeline 201c. The concentrated working medium B supplied to the second chamber 44 has a sufficiently high concentration with respect to the solvent-only water supplied to the first chamber 43. For this reason, an osmotic pressure difference occurs between the water in the first chamber 43 and the concentrated working medium B in the second chamber 44, and the water permeates the osmotic membrane 42 and moves into the second chamber 44. At this time, the working medium B in the second chamber 44 is an aqueous solution containing the solute of the embodiment and exhibits a high osmotic pressure inducing action. Therefore, when the water in the first chamber 43 permeates the permeable membrane 32 and moves to the working medium B in the second chamber 44, a high permeation flux is generated. As a result, a large amount of water in the first chamber 43 can be transferred to the concentrated working medium B in the second chamber 44, and the diluted working medium B diluted with water and having a high pressure is generated. The water in the first chamber 43 is discharged through the pipeline 201b.

  The dilution work medium B having a high pressure in the second chamber 44 is sent to the dilution work medium tank 32 through the pipeline 201d and stored. The pressure exchanger 81 and the rotating body 82 are provided in the pipeline 201d in this order along the flow direction of the working medium B.

  Therefore, as described above, in the pressure exchanger 81, the concentrated working medium B flowing from the concentrated working medium tank 34 through the pipeline 201c and the high pressure flowing from the second chamber 44 (through the rotating body 82) through the pipeline 201d are provided. The pressure is exchanged with the diluting working medium B, the pressure of the diluting working medium B is lowered, and the pressure of the concentrating working medium B is increased. By exchanging the pressure, the diluting working medium B having an appropriate pressure flows into the rotating body 82, and efficiently rotates it to generate electric power. Further, the concentration working medium B having an appropriate pressure is supplied to the second chamber 44 by pressure exchange.

  The diluting working medium B stored in the diluting working medium tank 32 includes the third working chamber 53 of the membrane distilling separator 33 and the diluting working medium circulation system 33 and the membrane distilling separator 33 as in the concentrating system 300 shown in FIG. It is concentrated by the pure water circulation cooling system including the fourth chamber 54. That is, the evaporation of the water of the dilution working medium B in the third chamber 53, the permeation of the dehydration film 52 of vapor, the movement to the fourth chamber 54, and the cooling and condensation by the circulating pure water on the fourth chamber 54 side are performed. By repeating the dehydration process performed a plurality of times, the diluted working medium B is stored in the circulation tank 64 as a working medium B (concentrated working medium B) having a concentration that can be used as the concentrated working medium B, and the concentrated working medium B is concentrated. Return to the medium tank 34. The concentrated working medium B in the concentrated working medium tank 34 is supplied into the second chamber 44 of the osmotic pressure generator 31 by driving the second pump 47 to rotate the rotating body 82 to generate electric power as described above. It

  Therefore, the power generation operation by the rotation of the rotor 82 by the osmotic pressure generator 31 and the concentration of the diluted working medium B by the membrane distillation separator 33 can be continuously executed. Therefore, it is possible to provide the circulating osmotic pressure power generation system 400 that can efficiently rotate the rotating body 82 such as the turbine to generate power and can be operated at low cost.

  In the circulation type osmotic pressure power generation system 400 shown in FIG. 5, the osmotic pressure generator horizontally partitions the first processing container with the osmotic membrane to form the first chamber 43 and the second chamber 44. The first chamber 43 and the second chamber 44 may be formed by partitioning the processing container into upper and lower parts with a permeable membrane.

  In the circulation type osmotic pressure power generation system 400 shown in FIG. 5, the water in the first chamber 43 of the osmotic pressure generator 31 was sent to the outside through the pipeline 201b, but the pipeline 201b was connected to the treated water tank 45. You may make the loop of the treated water tank 45, the pipeline 201a, the 1st chamber 43 of the osmotic pressure generator 31, and the pipeline 201b.

  In the circulation type osmotic pressure power generation system 400 shown in FIG. 5, the dehydration membrane 52 of the membrane distillation separator 33 is not limited to the porous latex membrane, and may be any one as long as it has a vapor permeation function.

  In the circulatory osmotic pressure power generation system 400 shown in FIG. 5, the concentration of the diluted working medium B is not limited to the case where it is carried out by the membrane distillation separator 33 having a dehydration membrane, and any water can be removed from the diluted working medium B. It may be performed by the device.

  Examples will be described below.

  The forward osmosis test was performed as follows. A CTI-ES membrane manufactured by HTI was set in the FO cell, pure water as water to be treated was put into the active surface side of the membrane, and then a working medium was put into the support layer side. The time when the working medium was completely added was set to 0 minute, and the work medium was allowed to stand for 20 minutes. After the test, the weight of the liquid on the active surface side was measured, and the permeation flux (Jw) was calculated from the difference before and after the test, with the specific gravity of the liquid being 1. The total organic carbon concentration in the liquid on the active surface side after the test was measured with a total organic carbon meter, and the cation concentration was measured with an ion chromatograph to calculate the solute loss (Js). Table 1 shows the solute contained in the working medium, its concentration, and the experimental results.

As is clear from Table 1, in Examples 1 to 7 in which the compound containing a plurality of phosphonic acid groups was used in the draw solution, the solute loss was very small as compared with the commonly used inorganic salts. In addition, Js / Jw is inferior to the examples in the comparative example in which the sodium salt having a carboxylic acid group is used as the solute. By using the working medium having such characteristics, the running cost of the water treatment system utilizing osmotic pressure can be reduced. In addition, power generation can be performed at low cost by generating power using the water flow generated by these osmotic pressure effects.
In the specification, some elements are represented only by element symbols.

  Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are also included in the invention described in the claims and the scope equivalent thereto.

A ... water to be treated,
B ... Work medium,
C ... Water 1, 31 ... Osmotic pressure generator,
2, 32 ... Diluting working medium tank,
3 ... Reverse osmosis membrane separator,
4, 34 ... Concentrated working medium tank,
11, 41 ... First processing container,
12, 42 ... Permeation membrane,
13, 43 ... First chamber,
14, 44 ... Second chamber,
15, 45 ... Treated water tank,
16 ... the first pump,
17 ... second pump,
21, 51 ... Second processing container,
22 ... Reverse osmosis membrane (RO membrane),
23, 53 ... Third chamber,
24, 54 ... Fourth chamber,
25 ... Third pump,
26 ... Pure water tank,
27 ... on-off valve,
33 ... Membrane distillation separator,
52 ... dehydration membrane,
61 ... First on-off valve,
62 ... Heat exchanger,
64 ... Circulation tank,
65 ... second on-off valve,
66 ... the fourth pump,
71 ... the first pure water tank,
72 ... second pure water tank,
73 ... Third on-off valve,
74 ... Fifth pump,
75 ... Fourth on-off valve,
81 ... Pressure exchanger,
82 ... a rotating body,
100 ... water treatment system,
101 ... pipeline,
200 ... desalination system,
201 ... Pipeline,
300 ... Concentration system 300,
400 ... Circulating osmotic pressure power generation system

Claims (10)

A first treatment container provided with a osmotic membrane that divides a first chamber for containing water to be treated and a second chamber for containing a working medium that induces osmotic pressure;
The working medium is a compound having a main chain, a side chain, or an ammonium salt structure of a phosphonic acid group in the main chain and the side chain, or a metal salt structure of a phosphonic acid group in the main chain, the side chain, or the main chain and the side chain. Containing as a solute a compound having
The compound having a metal salt structure of a phosphonic acid group in the main chain, the side chain, or the main chain and the side chain is a compound in which the phosphonic acid group of the compound having the structure represented by the formula (1) or (2) is a metal salt. A compound having a structure,
X ¹ , X ² and X ³ in the formula (1) are one selected from the group consisting of H and — (CH ₂ ) _m1 PO (OH) ₂ (m ₁ is any integer from 1 to 3). Is over,
A water treatment system in which Y ¹ and Y ^{2 in} the formula (2) are an aqueous solution which is one or more selected from the group consisting of OH, CH ₃ , Cl, Br and CH ₂ CH ₂ NH ₂ .
The main chain, a side chain, or a compound having a metal salt structure of a phosphonic acid group in the main chain and side chains and a main chain, a side chain, or a compound having an ammonium salt structure of a phosphonic acid group in the main chain and side chains, is represented by _{C x H y P z O w} N r Cl s Br t M u,
The M is an alkali metal or an alkaline earth metal, and x, y, z, w, r, s, t and u are 2 ≦ x ≦ 9, 8 ≦ y ≦ 28, 1 ≦ z ≦ 6, 3 The water treatment system according to claim 1, wherein ≦ w ≦ 18, 0 ≦ r ≦ 3, 0 ≦ s ≦ 1, 0 ≦ t ≦ 1, and 2 ≦ u ≦ 10 are satisfied.   The water treatment system according to claim 1, wherein a plurality of ammonium salt structures or metal salt structures of the phosphonic acid group are contained in the compound. The compound having an ammonium salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain is a phosphonic acid group of a compound having a structure represented by formula (1), (2) or (3). Is a compound having an ammonium salt structure,
X ¹ , X ² and X ³ in the formula (1) are one selected from the group consisting of H and — (CH ₂ ) _m1 PO (OH) ₂ (m ₁ is any integer from 1 to 3). Is over,
Y ¹ and Y ^{2 in} the formula (2) are one or more selected from the group consisting of OH, CH ₃ , Cl, Br and CH ₂ CH ₂ NH ₂ .
^{Z 1,} Z 2, ^{Z 3} and ^{Z 4} _{are, H,} of the formula _{(3) - (CH 2)} m2 PO (OH) 2 (m 2 is any one of 1 to 3 integer), - (CH _{2 ) m3 N ((CH 2)} m4 PO (OH) 2) 2 (m 3 is any one of 1 to 3 integer, 1 or more _{to m 4} is selected from the group consisting of any) from 1 to 3 of an integer The water treatment system according to any one of claims 1 to 3, wherein n is an integer of 2 or more and 10 or less.
  The compound having a metal salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain includes etidronate sodium salt, etidronate potassium salt, nitrotris (methylenephosphonic acid) sodium salt and nitrotris (methylenephosphonic acid). ) The water treatment system according to any one of claims 1 to 4, which is one or more selected from the group consisting of potassium salts.   Examples of the compound having an ammonium salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain include etidronic acid ammonium salt, nitrotris (methylenephosphonic acid) ammonium salt, ethylenediaminetetramethylenephosphonic acid ammonium salt and diethylenetriaminepentane. The water treatment system according to any one of claims 1 to 4, which is at least one selected from the group consisting of methylenephosphonic acid ammonium salts. The water treatment system according to any one of claims 1 to 6, further comprising a rotating body,
The induction of the osmotic pressure causes a water flow,
A water treatment system in which the rotating body is rotated by the water flow to generate electricity. A compound having an ammonium salt structure of a phosphonic acid group on the main chain, a side chain, or a main chain and a side chain, or a compound having a metal salt structure of a phosphonic acid group on the main chain, a side chain, or the main chain and a side chain. Contains as a solute,
The compound having a metal salt structure of a phosphonic acid group in the main chain, the side chain, or the main chain and the side chain is a compound in which the phosphonic acid group of the compound having the structure represented by the formula (1) or (2) is a metal salt. A compound having a structure,
X ¹ , X ² and X ³ in the formula (1) are one selected from the group consisting of H and — (CH ₂ ) _m1 PO (OH) ₂ (m ₁ is any integer from 1 to 3). Is over,
Y ¹ and Y ² of the formula (2) are one or more selected from the group consisting of OH, CH ₃ , Cl, Br and CH ₂ CH ₂ NH ₂ .
A working medium that is a solvent that induces osmotic pressure.
The compound having an ammonium salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain is a phosphonic acid group of a compound having a structure represented by formula (1), (2) or (3). Is a compound having an ammonium salt structure,
X ¹ , X ² and X ³ in the formula (1) are one selected from the group consisting of H and — (CH ₂ ) _m1 PO (OH) ₂ (m ₁ is any integer from 1 to 3). Is over,
Y ¹ and Y ^{2 in} the formula (2) are one or more selected from the group consisting of OH, CH ₃ , Cl, Br and CH ₂ CH ₂ NH ₂ .
^{Z 1,} Z 2, ^{Z 3} and ^{Z 4} _{are, H,} of the formula _{(3) - (CH 2)} m2 PO (OH) 2 (m 2 is any one of 1 to 3 integer), - (CH _{2 ) m3 N ((CH 2)} m4 PO (OH) 2) 2 (m 3 is any one of 1 to 3 integer, 1 or more _{to m 4} is selected from the group consisting of any) from 1 to 3 of an integer der is,
N is the working medium of claim 8 Ru integer der of 2 to 10 in the formula (3).
  Concentration of a compound having an ammonium salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain, and a compound having a metal salt structure of a phosphonic acid group in main chain, side chain, or main chain and side chain Is 10 mass% or more and 70 mass% or less, The working medium of Claim 9.