JP2018158300A - Water treatment system and work medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment system that can separate water at low cost, and a work medium.SOLUTION: A water treatment system according to one embodiment has a first treatment vessel having an osmosis membrane that divides a first chamber for storing water to be treated and a second chamber for storing a work medium to induce an osmotic pressure, where the work medium is aqueous solution containing a compound having an ammonium salt structure of a phosphonic acid group in a main chain, a side chain, or the main chain and the side chain, or a 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.SELECTED DRAWING: Figure 1

Description

  Embodiments relate to a water treatment system and a working medium.

  When a solution having a low solute concentration and a solution having a high solute concentration are separated from each other by the osmosis membrane, the solvent of the solution having a low concentration passes through the osmosis membrane and moves to the solution side having a high concentration. There are known desalination systems that perform desalination such as seawater desalination by utilizing this phenomenon of solvent movement, and osmotic pressure power generation systems that generate power by turning a turbine. In addition, a concentration system that concentrates food and sludge using the same is also known. At this time, the working medium (Draw solution) is used on the higher 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, organic salt draw solutions have inferior water flux compared to salt draw solutions.

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

Special table 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 contains water to be treated and a second chamber that contains a working medium that induces osmotic pressure, and the working medium Is a compound having an ammonium salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain, or a compound having a metal salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain Is an aqueous solution containing as a solute.

Schematic of the water treatment system concerning an embodiment. The chemical formula of the solute which concerns on embodiment. Schematic of the water treatment system concerning an embodiment. Schematic of the water treatment system concerning an embodiment. Schematic of the water treatment system concerning an embodiment.

Hereinafter, the working medium used for the water treatment system and water treatment system of an embodiment is explained.
(First embodiment)
The water treatment system according to the first embodiment will be described with reference to the schematic diagram shown in FIG. A water treatment system 100 according to the first embodiment shown in FIG. 1 includes a permeable membrane 12 that partitions 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 osmotic pressure.

  According to such a water treatment system 100, in the water to be treated A in the first chamber 13 due to the osmotic pressure difference generated between the water to be treated A in the first chamber 13 and the working medium B in the second chamber 14. The water C passes through the osmotic 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 is transferred to the working medium B in the second chamber 14 through the osmotic membrane with a large permeation flux. Therefore, the water treatment system of the embodiment is preferable. The working medium B of the embodiment is used in a water treatment system that can be operated at low cost, and a water treatment system.

  The first processing container 11 is partitioned by a permeable membrane 12 into a first chamber 13 and a second chamber 14. The first treatment container 11 is a resin or metal container in which the water to be treated A is accommodated in the first chamber 13 and the work medium B is accommodated in the second chamber 14.

  For example, the osmosis membrane 12 may be a forward osmosis membrane (FO membrane) or a reverse osmosis membrane (RO membrane). A preferred osmotic membrane is an FO membrane.

  As the osmotic 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 a region in the first processing container 11 that stores the water to be treated A, and is partitioned by the permeable membrane 12. The first chamber 13 may be provided with an introduction / discharge path (not shown) through which the treated water A is introduced / discharged.

  The water to be treated A is a liquid having a lower solute concentration than the working medium. The treated water A can include, for example, salt water (seawater, etc.), lake water, river water, marsh water, domestic wastewater, industrial wastewater, or a mixture thereof. When the to-be-processed water A is salt water, the salt (sodium chloride) density | concentration of salt water should just be 0.05%-8%, for example. The water to be treated A contains salts such as sodium chloride, magnesium chloride, magnesium sulfate, calcium sulfate, potassium chloride, and suspended solids, and concentrates other than water.

  The second chamber 14 is a region in the first processing container 11 that accommodates the working medium B, and is partitioned by the permeable membrane 12. The second chamber 13 may be provided with an introduction / discharge path (not shown) through which the work medium B is introduced / discharged.

The working medium B according to the first embodiment includes a main chain, a side chain, or a compound having 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. An aqueous solution containing a compound having an ammonium salt structure 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. For this reason, when the water in the to-be-treated water A in the first chamber 11 permeates the osmotic 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 be operated at a low cost and can efficiently carry out treatments such as desalting and concentration of the water to be treated A. It is also preferable that the water treatment system of the embodiment further includes a rotating body, and a water flow is generated by inducing osmotic pressure, and the water treatment system generates power by rotating the rotating body by the water flow.

  The solute contained in the working medium B leaks 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 with low molecular weight solutes. 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, the concentration in the high molecular weight working medium B is low, so it is difficult to achieve a high permeation flow rate.

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

Compound having metal salt structure of phosphonic acid group in main chain, side chain, main chain and side chain of embodiment and compound having ammonium salt structure of phosphonic acid group in main chain, side chain, main chain and 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 rate, 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. In order to reduce the reverse flow rate of the solute, 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. In order to increase the permeation flow rate and reduce 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 to satisfy s ≦ 1, 0 ≦ t ≦ 1, 2 ≦ u ≦ 10. 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 members 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 analyzed by liquid chromatography, each peak compound can be separated, and determined by NMR or an organic element analyzer.

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

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

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

Z ¹ , Z ² , Z ³ and Z ⁴ in the formula (3) are H, — (CH ₂ ) _{m 2} PO (OH) ₂ (m ₂ is any integer of 1 to 3), — (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) in FIG. 2 is an integer of 2 or more and 10 or less. As the compound having a structure represented by the formula (3) in FIG. 2, ethylenediaminetetramethylenephosphonic acid and diethylenetriaminepentamethylenephosphonic acid are preferable. Examples of the compound in which the phosphonic acid group of the compound represented by the formula (3) in FIG. 2 has a metal salt structure include ethylenediaminetetramethylenephosphonic acid sodium salt, diethylenetriaminepentamethylenephosphonic acid sodium salt, ethylenediaminetetra Examples include potassium methylenephosphonate and potassium diethylenetriaminepentamethylenephosphonate. As the compound in which the phosphonic acid group of the compound having a 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.

  Accordingly, compounds having a metal salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain include etidronate sodium salt, etidronate potassium salt, nitrotris (methylenephosphonic acid) sodium salt, nitrotris (methylenephosphon). Acid) potassium salt, ethylenediaminetetramethylenephosphonic acid sodium salt, diethylenetriaminepentamethylenephosphonic acid sodium salt, ethylenediaminetetramethylenephosphonic acid potassium salt and diethylenetriaminepentamethylenephosphonic acid potassium salt Is preferred.

  Accordingly, compounds having an ammonium salt structure of phosphonic acid group in the main chain, side chain, or main chain and side chain are etidronate ammonium salt, nitrotris (methylenephosphonic acid) ammonium salt, ethylenediaminetetramethylenephosphonic acid ammonium salt and diethylenetriamine. Any one or more members selected from the group consisting of ammonium pentamethylenephosphonates are preferred.

  The substitution number of the alkali metal salt or ammonium salt varies depending on the 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 near neutrality, but from the viewpoint of osmotic pressure, a larger number of substitutions is preferable. 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 it with a glass electrode type hydrogen ion concentration meter manufactured by Horiba by the method described in the manual.

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

(Second Embodiment)
Next, a desalination system as an example of the water treatment system will be described with reference to a schematic diagram shown in FIG. In 2nd Embodiment, the 1st chamber 13, the to-be-processed water A, the 2nd chamber 14, the working medium B, and the permeable membrane 12 are common in 1st Embodiment. The treated water A is salt water (sodium chloride aqueous 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, reference numerals of the water to be treated, the working medium, and water in the water treatment system are not shown, but these signs are common to the water treatment system of FIG.

  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 dilution working medium tank 2, the reverse osmosis membrane separation unit 3, and the concentrated working medium tank 4 are connected in this order to form a loop. The working medium B (draw solution) that induces osmotic pressure circulates in this loop. That is, the working medium B circulates through the osmotic pressure generator 1, the diluted working medium tank 2, the reverse osmosis membrane separator 3 and the concentrated working medium tank 4 in this order. The upper and lower sides are directions shown in the drawing. For example, the concentration working medium tank 4 is above 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 to-be-processed water tank 15 is connected to the upper part of the processing container 10 in which the 1st chamber 13 is located through the pipeline 101a. The first pump 16 is provided in the pipeline 101a. A pipeline 101b for discharging the concentrated water A to be treated is connected to the lower portion of the first treatment container 11 where the first chamber 13 is located.

  The reverse osmosis membrane separation unit 3 includes, for example, an airtight second processing vessel 21. The second processing vessel 21 is partitioned, for example, in a horizontal direction by, for example, 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 working medium tank 2 is connected to the lower part of the second processing vessel 21 where the third chamber 23 is located through a pipeline 101e. The third pump 25 is provided in the pipeline 101e. The upper part of the second processing vessel 21 in which the third chamber 23 is located is connected to the concentration work medium tank 4 through a pipeline 101f. The lower part of the second processing vessel 21 where the fourth chamber 24 is located is connected to the pure water tank 26 through a pipeline 101g. The pure water tank 26 stores water (fresh water) that has moved through the reverse osmosis membrane 22 and moved to the fourth chamber when the working medium B is concentrated. Connected to the pure water tank 26 is a pipeline 101h for sending and collecting the pure water in the pure water tank 26 to the outside. The on-off valve 27 is provided in the pipeline 101h. For example, it is opened when the pure water in the pure water tank 26 exceeds a certain amount.

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

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

  The first pump 16 is driven to supply the treated water A (for example, seawater) from the treated water tank 15 into the first chamber 13 of the osmotic pressure generator 1 through the pipeline 101a. Before and after 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 seawater supplied to the first chamber 13. For this reason, an osmotic pressure difference is generated 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 passes through the osmotic 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. For this reason, when the water in the seawater in the first chamber 13 permeates the osmotic membrane 12 and moves to the concentration 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 concentration working medium B in the second chamber 14, and a highly efficient desalting process for extracting water (pure water) from the salt water can be performed.

  In the osmotic pressure generator 1, when the water in the seawater moves from the first chamber 13 to the concentration 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 diluted working medium B in the second chamber 14 is sent to the diluted working medium tank 2 through the pipeline 101d and stored. 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 processing container of the reverse osmosis membrane separation unit 3. The third chamber 23 is supplied at a desired pressure through the pipeline 101e. The water in the diluted working medium B supplied to the third chamber 23 at a desired pressure is forced to permeate the reverse osmosis membrane (RO membrane) 22 and move 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 takes out water (pure water) from the salt water as described above. Used for desalting.

  On the other hand, the water (pure water) 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 on-off valve 27 is opened and sent to the outside through the pipeline 101h to collect the water.

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

  In the desalination system 200 shown in FIG. 3, the osmotic pressure generator forms the first chamber 13 and the second chamber 14 by partitioning the first processing vessel 11 horizontally by the osmosis membrane. The first chamber 13 and the second chamber 14 may be formed by dividing the upper and lower sides by a permeable membrane.

  When the solute concentration of the working medium B is reduced by performing 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 concentration of the diluted working medium B is not limited to being performed in a reverse osmosis membrane separation unit including a reverse osmosis membrane (RO membrane), but may be used to remove water from the diluted working medium B. Any apparatus may be used.

(Third embodiment)
Next, a concentration system 300 as an example of the water treatment system will be described with reference to a 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. The working medium B (draw solution) circulates in this loop. That is, the working medium B circulates through the osmotic pressure generator 31, the diluted working medium tank 32, the membrane distillation separator 33, and the concentrated 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 partitioned, for example, in a horizontal direction by a osmotic membrane 42 (for example, a normal osmosis 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. A to-be-treated water tank 45 containing a to-be-treated water A, for example, an undiluted solution such as industrial wastewater, is connected to the 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 where the first chamber 43 is located.

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

  The membrane distillation separator 33 includes, for example, an airtight second processing vessel 51. The second processing container 51 is partitioned, for example, in a horizontal direction 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 dilution working medium tank 32 is connected through a pipeline 201e to the lower part of the second processing vessel 51 where the third chamber 53 is located. The first on-off valve 61, the heat exchanger 62, and the third pump 63 are provided in this order along the flow direction of the working medium B in the pipeline 201e. For example, a waste heat gas pipeline 201f intersects the heat exchanger 62, and the work medium B flowing through the pipeline 201e exchanges heat with the exhaust heat gas to heat the work medium B. The upper part of the second processing vessel 51 where the third chamber 53 is located is connected to the upper part of the circulation tank 64 through a pipeline 201g. The circulation tank 64 is connected to a portion of the pipeline 201e located between the first on-off valve 61 and the heat exchanger 62 through the pipeline 201h. The second on-off 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 pipelines 201e, 201g, and 201h that connect these members. That is, the diluted working medium B dehydrated in the third chamber 53 described later and stored in the circulation tank 64 opens the second on-off valve 65 and drives the third pump 63, whereby the pipeline 201h and the pipeline 201e. A dilution working medium circulation system is circulated through the third chamber 53 and the pipeline 201g. In the circulation of the diluted working medium B, the diluted working medium circulation system is isolated from the diluted working medium tank 32 by closing the first on-off 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 part of the second processing vessel 51 where the fourth chamber 54 is located through a pipeline 201j. The lower part of the second processing vessel 51 where the fourth chamber 54 is located is connected to the second pure water tank 72 through a pipeline 201k. The third on-off valve 73 is provided in the pipeline 201k and closes when the pure water is not circulated so that the pure water stays 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 pipelines 201j, 201k, 201m connecting these members. That is, the pure water in the second pure water tank 72 opens the third on-off valve 73 and drives the fifth pump 74, thereby causing the pipeline 201 m, the first pure water tank 71, the pipeline 201 j, and the fourth chamber 54. And the pure water circulation cooling system which circulates through the pipeline 201k is formed.

  Connected to the second pure water tank 72 is a pipeline 201n for sending out and collecting the pure water in the second pure water tank 72 to the outside. The fourth on-off valve 75 is provided in the pipeline 201n. The fourth on-off 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 a raw solution (for example, industrial wastewater) as the water to be treated A from the water tank 45 to be treated 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. For this reason, an osmotic pressure difference is generated 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 passes through 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. For this reason, when the water in the undiluted solution in the first chamber 43 passes through the osmotic 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 moved to the working medium B in the second chamber 44, and the concentration process of the stock solution is made highly efficient.

  In the osmotic pressure generator 31, the water in the stock solution moves from the first chamber 43 to the concentration working medium B in the second chamber 44, whereby the stock solution is discharged from the first chamber 43 through the pipeline 201b as a concentrated stock solution. Collected. The concentrated working medium B is diluted with the moved water.

  The diluted working medium B in the second chamber 44 is sent to the diluted working medium tank 32 through the pipeline 201d and stored. When the diluted working medium B is stored up to a predetermined amount in the diluted working medium tank 32, the first on-off valve 61 provided on the pipeline 201e is opened, the second on-off valve 65 provided on the pipeline 201h is closed, and the third The pump 63 is driven. As a result, the diluted working medium B in the diluted 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 in the heat exchanger 62 where the pipeline 201f intersects. And heated. Also, the pure water in the second pure water tank 72 is opened by opening the third on-off valve 73 and driving the fifth pump 74, whereby pure water is supplied to the pipeline 201m, the first pure water tank 71, the pipeline 201j, The dehydration membrane 52 made of the porous latex membrane of the membrane distillation separator 33 is cooled with pure water from the fourth chamber 54 side by circulating through the four chambers 54 and the pipeline 201k. That is, the dehydration 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 dehydrated membrane 52 of the membrane distillation separator 33 is made of pure water circulating in the fourth chamber 54. By cooling, the water in the dilution working medium B evaporates in the third chamber 53, and the vapor passes through the dehydration film 52 made of a porous latex film and moves to the fourth chamber 54 to circulate pure water. It is cooled, condensed and taken into it. That is, the diluted working medium B is dehydrated in the third chamber 53. The dehydrated diluted working medium B in the third chamber 53 is sent to the circulation tank 64 through the pipeline 201g and stored. The diluted working medium B stored in the circulation tank 64 is concentrated to a certain concentration by the dehydration process.

  However, this level of concentration is low in concentration and is not suitable for use as the above-described concentrated working medium B. Therefore, when the dehydrated diluted working medium B is stored in the circulation tank 64 in a certain amount, the second on-off valve 65 is opened, and the dehydrated diluted working medium B in the tank 64 is put into the pipeline 201h. leak. At the same time, the first on-off valve 61 is closed, and the diluted working medium circulation system including the circulation tank 64, the pipeline 201h, the pipeline 201e, the third chamber 53, and the pipeline 201g is isolated from the diluted working medium tank 32.

  In such a dilution work medium circulation system and pure water circulation cooling system, the evaporation of water of the dilution work medium B in the third chamber 53, the permeation of the vapor dehydration film 52, the movement to the fourth chamber 54, And the dilution work medium B is made a concentration that can be used as the concentrated work medium B by repeating the dehydration process of cooling and condensing with the pure water circulating on the fourth chamber 54 side a plurality of times. After such circulation and dehydration of the diluted working medium B, the second on-off valve 65 is closed and the concentrated working medium B is stored in the circulation tank 64. The water (pure water) moved to the fourth chamber 54 is sent out together with the pure water circulating 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, and the circulation of pure water to the fourth chamber 54 is stopped, 3. Close the on-off valve 73. When the pure water in the second pure water tank 72 exceeds a certain amount, the first on-off valve 75 is opened and sent 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. As described above, the concentrated working medium B in the concentrated working medium tank 34 is supplied to the second chamber 44 of the osmotic pressure generator 31 by driving the second pump 47 so as to be used for the concentration process of the stock solution.

  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 to the second chamber 44. The stock solution is moved to the medium B, concentrated, 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 the diluted working medium tank 32 and stored.

  During the concentration operation of the stock solution by the osmotic pressure generator 31, the diluted working medium B stored in the diluted working medium tank 32 is diluted with the diluted working medium circulation system including the third chamber 53 of the membrane distilled separator 33 and the membrane distilled separator 33. Concentration operation is performed by the pure water circulation cooling system including the fourth chamber 54, and the water (pure water) sent to the concentration working medium tank 34 and moved to the fourth chamber 54 is sent out from the second pure water tank 72 and collected. Is 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 executed continuously.

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

  In the concentration system 300 shown in FIG. 4, the osmotic pressure generator forms the first chamber 43 and the second chamber 44 by partitioning the first processing container 41 in the horizontal direction by the osmosis membrane. The first chamber 43 and the second chamber 44 may be formed by dividing them vertically with a permeable membrane.

  In the concentration system 300 shown in FIG. 4, the concentrated water to be treated A (for example, a stock solution) in the first chamber 43 of the osmotic pressure generator 31 is sent out and recovered through the pipeline 201b, but is concentrated to a higher concentration. When the obtained stock solution is obtained, the pipeline 201b is connected to the water tank 45 to be treated to form a loop of the 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 concentration degree of the stock solution in consideration of the osmotic pressure difference between the concentrated stock solution and the concentrated working medium B in the osmotic pressure generator 31.

  In the concentration 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 device as long as it has a function of transmitting vapor.

  In the concentration system 300 shown in FIG. 4, the concentration of the diluted working medium B is not limited to being performed by the membrane distillation separator 33 including the dehydrating membrane 52, but may be performed by any apparatus that can remove the water of the diluted working medium B. May be.

(Fourth embodiment)
Next, a circulation type osmotic pressure power generation system 400 as an example of the water treatment system according to the fourth embodiment will be described with reference to a schematic diagram shown in FIG. In FIG. 5, the same members as those in FIG. 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 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 for containing water, a second chamber 44 for containing a working medium B (draw solution) for inducing osmotic pressure, and a first chamber and a second chamber. And a pressure exchanger 81 connected to the second chamber 44, and a 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. Move to the working medium B in the second chamber 44. The rotating body 82 is rotated by the water flow accompanying the movement of the water to the working medium B to generate electric power.

  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. For this reason, when the water in the first chamber 43 passes through the osmotic membrane 42 and moves to the working medium B in the second chamber 44, a high permeation flux can be generated. As a result, since the working medium B to which the water has been moved becomes a water stream having a high pressure, the rotating body 82 can be rotated at a higher speed to generate electric power. Therefore, it is possible to provide a water treatment system that can efficiently operate by rotating the rotating body 82 and can be operated at a low cost.

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

  The circulation type osmotic pressure power generation system 400 includes a pressure exchanger 81 and a rotation in a pipeline 201b connected to a lower portion (working medium B outlet side) 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 part of the first processing vessel 41 where the second chamber 44 is located and the concentrated working medium tank 34, the pipeline 201c portion on the downstream side in the flow direction of the working medium B from the second pump 47 Is connected to the upper part of the first processing vessel 41 where the second chamber 44 is located via a pressure exchanger 81. That is, in the osmotic pressure generator 31, the second chamber 44 is located in the diluted working medium B having a flux generated when water passes from the first chamber 43 through the osmotic membrane 42 and moves to the second chamber 44. It flows out from the lower part of the 1st processing container 41 through the pipeline 201b in which the pressure exchanger 81 was provided. During this time, the pipeline 201 c through which the concentrated working medium B flowing out from the concentrated working medium tank 34 passes through the pressure exchanger 81. For this reason, the concentrated working medium B is pressure-exchanged with the diluted working medium B flowing out from the second chamber 44 by the pressure exchanger 81, the diluted working medium B decreases the pressure, and the concentrated working medium B increases the pressure.

  In the circulation type osmotic pressure power generation system 400, water is accommodated in the water tank 45 to be treated.

Next, 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 relative to the water of only the solvent supplied to the first chamber 43. For this reason, an osmotic pressure difference is generated between the water in the first chamber 43 and the concentrated working medium B in the second chamber 44, and the water passes through 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. For this reason, when the water in the first chamber 43 passes through the osmotic 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 moved to the concentrated working medium B in the second chamber 44, and a diluted working medium B having a high pressure diluted with water is generated. The water in the first chamber 43 is discharged through the pipeline 201b.

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

  For this reason, as described above, the pressure exchanger 81 has the concentrated work medium B flowing from the concentrated work 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. The pressure is exchanged with the diluted working medium B, the pressure of the diluted working medium B is lowered, and the pressure of the concentrated working medium B is raised. The diluted working medium B having an appropriate pressure by pressure exchange flows into the rotating body 82 and efficiently rotates it to generate electric power. Further, the concentrated working medium B having an appropriate pressure is supplied to the second chamber 44 by pressure exchange.

  The diluted working medium B stored in the diluted working medium tank 32 is diluted with the diluted working medium circulation system including the third chamber 53 of the membrane distillation separator 33 and the membrane distillation separator 33 in the same manner as the concentration system 300 shown in FIG. The pure water circulation cooling system including the fourth chamber 54 is concentrated. That is, evaporation of water of the diluted working medium B in the third chamber 53, permeation of the vapor dehydration film 52, movement to the fourth chamber 54, and cooling and condensation by circulating pure water on the fourth chamber 54 side. By repeating the dehydration process to be performed a plurality of times, the diluted working medium B is stored in the circulation tank 64 as a working medium B having a concentration that can be used as the concentrated working medium B (concentrated working medium B), and the concentrated working medium B is concentrated. Return to media tank 34. As described above, 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 in order to generate electric power by rotating the rotating body 82. The

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

  In the circulation type osmotic pressure power generation system 400 shown in FIG. 5, the osmotic pressure generator forms the first chamber 43 and the second chamber 44 by dividing the first processing container horizontally by the osmotic membrane. The first chamber 43 and the second chamber 44 may be formed by dividing the processing container up and down 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 is sent to the outside through the pipeline 201b, and the pipeline 201b is connected to the water tank 45 to be treated. You may make the loop of the to-be-processed water tank 45, the pipeline 201a, the 1st chamber 43 of the osmotic pressure generator 31, and the pipeline 201b.

  In the circulatory 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 anything as long as it has a function of permeating vapor.

  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 being performed by the membrane distillation separator 33 provided with a dehydrating membrane, and any method can be used as long as it removes water from the diluted working medium B. You may carry out with an apparatus.

  Examples will be described below.

  The forward osmosis test was conducted as follows. A CTA-ES membrane manufactured by HTI was set in the FO cell, pure water was added as treated water to the active surface side of the membrane, and then a working medium was placed on the support layer side. The time when the working medium was put in was set to 0 minutes, and 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. Further, the total organic carbon concentration in the liquid on the active surface side after the test was measured with a total organic carbon meter, the cation concentration was measured with an ion chromatograph, and the solute loss (Js) was calculated. Table 1 shows the solute contained in the working medium, its concentration, and the experimental results.

As is apparent from Table 1, Examples 1 to 7 using a compound containing a plurality of phosphonic acid groups in the draw solution have a very small loss of solute with respect to generally used inorganic salts. Moreover, in the comparative example using the sodium salt which has a carboxylic acid group as a solute, Js / Jw is inferior to an Example. By using a working medium having such characteristics, the running cost of the water treatment system using osmotic pressure can be reduced. Moreover, it can generate electric power at low cost by generating electric power using the water flow produced by these osmotic pressure actions.
In the specification, some elements are represented only by element symbols.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example 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 scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

A ... treated water,
B ... Working medium,
C ... water 1, 31 ... osmotic pressure generator,
2, 32 ... Dilution working medium tank,
3 ... Reverse osmosis membrane separator,
4, 34 ... Concentrated working medium tank,
11, 41 ... 1st processing container,
12, 42 ... osmotic membrane,
13, 43 ... first chamber,
14, 44 ... second chamber,
15, 45 ... treated water tank,
16 ... first pump,
17 ... second pump,
21, 51 ... second processing vessel,
22 ... Reverse osmosis membrane (RO membrane),
23, 53 ... the third chamber,
24, 54 ... the fourth chamber,
25 ... the third pump,
26 ... pure water tank,
27: On-off valve,
33 ... Membrane distillation separator,
52 ... dehydration membrane,
61 ... 1st on-off valve,
62 ... heat exchanger,
64 ... circulation tank,
65 ... second on-off valve,
66 ... Fourth pump,
71 ... the first pure water tank,
72 ... the second pure water tank,
73 ... third on-off valve,
74 ... Fifth pump,
75 ... Fourth on-off valve,
81 ... pressure exchanger,
82 ... Rotating body,
100 ... water treatment system,
101 ... Pipeline,
200 ... desalination system,
201 ... pipeline,
300 ... Concentration system 300,
400 ... Circulation type osmotic pressure power generation system

Claims (10)

A first treatment container having a osmosis membrane for partitioning a first chamber containing water to be treated and a second chamber containing a working medium for inducing osmotic pressure;
The working medium is 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 chain, or a metal salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain The water treatment system which is the aqueous solution which contains the compound which has this as a solute. A compound having a metal salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain, and a compound having an ammonium salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain, is represented by _{C x H y P z O w} N r Cl s Br t M u,
M is an alkali metal or 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 satisfying ≦ w ≦ 18, 0 ≦ r ≦ 3, 0 ≦ s ≦ 1, 0 ≦ t ≦ 1, 2 ≦ u ≦ 10.   The water treatment system according to claim 1 or 2, wherein the compound includes a plurality of ammonium salt structures or metal salt structures of the phosphonic acid group. A compound having a metal salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain, and a compound having an ammonium salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain are The compound having the structure represented by formula (1), (2) or (3) is a compound in which the phosphonic acid group has an ammonium salt structure or the phosphonic acid group has a metal salt structure,
X ¹ , X ² and X ³ in the formula (1) are one selected from the group consisting of H, — (CH ₂ ) _m1 PO (OH) ₂ (m ₁ is any _one of 1 to 3). That's it,
Y ¹ and Y ^{2 in} the formula (2) are at least one 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 in the formula (3) are H, — (CH ₂ ) _{m 2} PO (OH) ₂ (m ₂ is any integer of 1 to 3), — (CH ₂ ) _M3 N ((CH ₂ ) _m4 PO (OH) ₂ ) ₂ (one or more selected from the group consisting of m ₃ is any integer from 1 to 3, and m ₄ is any integer from 1 to 3) The water treatment system according to any one of claims 1 to 3.
  Compounds having a metal salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain are etidronate sodium salt, etidronate potassium salt, nitrotris (methylenephosphonic acid) sodium salt, nitrotris (methylenephosphonic acid) A potassium salt, ethylenediaminetetramethylenephosphonic acid sodium salt, diethylenetriaminepentamethylenephosphonic acid sodium salt, ethylenediaminetetramethylenephosphonic acid potassium salt and diethylenetriaminepentamethylenephosphonic acid potassium salt. The water treatment system according to any one of 1 to 4.   Compounds having an ammonium salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain include etidronate ammonium salt, nitrotris (methylenephosphonic acid) ammonium salt, ethylenediaminetetramethylenephosphonic acid ammonium salt and diethylenetriaminepenta. The water treatment system according to any one of claims 1 to 4, wherein the water treatment system is at least one member selected from the group consisting of ammonium methylenephosphonates. The water treatment system according to any one of claims 1 to 6, further comprising a rotating body,
Due to the induction of the osmotic pressure, a water flow is generated,
A water treatment system for generating electricity by rotating the rotating body by the water flow.   The working medium used for the water treatment system of any one of Claim 1 thru | or 7.   A compound having an ammonium salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain, or a compound having a metal salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain. A working medium that is an aqueous solution containing a solute. A compound having a metal salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain, and a compound having an ammonium salt structure of a phosphonic acid group in the main chain, side chain, or main chain and side chain are The compound having the structure represented by formula (1), (2) or (3) is a compound in which the phosphonic acid group has an ammonium salt structure or the phosphonic acid group has a metal salt structure,
X ¹ , X ² and X ³ in the formula (1) are one selected from the group consisting of H, — (CH ₂ ) _m1 PO (OH) ₂ (m ₁ is any _one of 1 to 3). That's it,
Y ¹ and Y ^{2 in} the formula (2) are at least one 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 in the formula (3) are H, — (CH ₂ ) _{m 2} PO (OH) ₂ (m ₂ is any integer of 1 to 3), — (CH ₂ ) _M3 N ((CH ₂ ) _m4 PO (OH) ₂ ) ₂ (one or more selected from the group consisting of m ₃ is any integer from 1 to 3, and m ₄ is any integer from 1 to 3) The working medium according to claim 9.