JP7186579B2 - Working media and water treatment systems for use in water treatment - Google Patents

Description

Embodiments relate to working media and water treatment systems for use in water treatment .

When a solution with a low solute concentration and a solution with a high solute concentration are separated by an osmotic membrane, the solvent of the low concentration solution permeates the osmotic membrane and moves to the high concentration solution side. A water treatment system that utilizes this phenomenon of solvent movement is known. Examples of such water treatment systems include those that thicken food and sludge. At this time, a working medium (draw solution) is used on the high-concentration side, and various ones have been proposed so far, and a lower running cost is desired.

Japanese translation of PCT publication No. 2013-518718

Embodiments provide amine compounds, working media, and water treatment systems capable of separating water at low running costs.

In order to achieve the above objects, a working medium for use in water treatment of an embodiment contains water and an amine compound, and phase-separates when the temperature rises above a predetermined temperature, wherein the amine The compounds are ethyl 4-{3-[4-(ethoxycarbonyl)piperazin-1-yl]propyl}piperazine-1-carboxylate, propyl 4-{3-[4-(propoxycarbonyl)piperazin-1-yl] propyl}piperazine-1-carboxylate, or 1,1'-(1,3-propanediyl)bis-pyrrolidine.

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. FIG. 4 shows the results of a phase separation test using ethyl 4-{3-[4-(ethoxycarbonyl)piperazin-1-yl]propyl}piperazine-1-carboxylate.

Hereinafter, the water treatment system of the embodiment and the working medium used in the water treatment system will be described.

(First embodiment)
A water treatment system according to a 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. In an osmotic pressure generator 1 and a concentrator 2 having a first processing vessel (not shown), the working medium B induces an osmotic pressure in the osmotic pressure generator 1 and heats the working medium B in the concentrator 2. As a result, the working medium B undergoes phase separation into purified water and concentrated working medium B. Therefore, water treatment can be performed at low cost.

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

The working medium B is separated from water by heating to a predetermined temperature or higher, and the working medium B is concentrated. The predetermined temperature can be calculated by heating the working medium B to be used and measuring the temperature at which separation is achieved efficiently. Specifically, a working medium mixed with water is placed in a volumetric container, which is sealed, and the container is placed in a water bath and allowed to stand. After confirming that the water bath temperature reaches the set value, the temperature is maintained for about 30 minutes. Remove the container from the water bath and let stand at room temperature for 1 hour. The organic carbon concentration of the supernatant is measured, and the phase separation rate is calculated using Equation 1 below. It is desirable to change the set temperature and perform the separation at the temperature at which the phase separation rate is the highest.

(Number 1)
Phase separation rate (%) = 100 - aqueous phase side concentration at phase separation * aqueous phase side volume at phase separation) / (concentration of working medium when homogeneous solution * volume of working medium when homogeneous solution)
To concentrate the working medium B, solid-liquid separation or liquid-liquid separation is performed. The working medium B is concentrated by this step and again becomes a medium that easily induces osmotic pressure. Therefore, in the embodiment, water treatment is performed at low running cost.

By using the working medium B of the embodiment, the water C in the water A to be treated in the first chamber 13 permeates the permeation membrane with a large permeation flux and moves to the working medium B in the second chamber 14. is possible, 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 in a water treatment system.

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

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

For the permeable 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 within the first treatment container that stores the water A to be treated, 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 water A to be treated is introduced/discharged.

The water A to be treated is a liquid having a lower solute concentration than the working medium. The water A to be treated can include, for example, salt water (seawater, etc.), lake water, river water, swamp water, domestic wastewater, industrial wastewater, or a mixture thereof. When the water to be treated A is salt water, the salt (sodium chloride) concentration of the salt water may be, for example, 0.05% to 8%. The water to be treated A contains salts such as sodium chloride, magnesium chloride, magnesium sulfate, calcium sulfate, and potassium chloride, and suspended substances, and substances other than water are concentrated by the water treatment of this embodiment.

The second chamber 14 is a region within the first processing vessel that contains the working medium B and is separated by the permeable membrane 12 .

The concentrator 2 includes heating means (not shown) for heating the working medium B and phase separation means (not shown) for separating the phase-separated working medium B. In addition, the concentrator 2 may further include means for cooling the working medium B and storage means for storing the concentrated working medium B. As the phase separation means, a plate-type, cylinder-type, or decanter-type centrifugal separator can be used. A heating device or the like can be used as the heating means. From the viewpoint of energy cost, it is preferable to employ a heat exchanger that utilizes exhaust heat for the heating device.

The working medium B of the first embodiment contains an amine compound whose properties change according to temperature, and water. In the working medium B of the embodiment, when the temperature of the working medium B is heated to a predetermined temperature or higher, the amine compound separates from water, so that the working medium B can be concentrated.

Water generated by concentration of working medium B may contain a low concentration of amine compounds. This is the loss of amine compounds. Moreover, if the water treatment is desalination, the concentration of the working medium B results in impurities in the water. Therefore, when the water generated by the concentration of the working medium B contains a low-concentration amine compound, the water generated by the concentration of the working medium B is further concentrated with a reverse osmosis membrane separator to obtain a concentrated working medium B can be recovered and purified water can be obtained. In the operation with the reverse osmosis membrane separator, since the concentration of amine compounds in the water to be treated is low, the water treatment can be performed with less energy than the concentration treatment of the water to be treated only with the reverse osmosis membrane separator. In the concentrator 2, there is a large cost difference between the reverse osmosis membrane separation and the concentration according to the embodiment, and the water treatment according to the embodiment is superior in terms of cost.

The amine compound of the embodiment changes its solubility in water depending on the temperature of the medium. Using this characteristic, the working medium B is concentrated. As a method of heating the working medium B, for example, it may be heated by utilizing exhaust heat from a power plant or the like.

When the temperature of the working medium B rises above a predetermined temperature, the solubility of the amine compound in water decreases, and the working medium B enters a solid-liquid separated state or a liquid-liquid separated state. On the other hand, when the temperature of the working medium B drops below a predetermined temperature, the solubility of the amine compound in water increases, and the working medium B becomes a one-phase aqueous solution.

In the case of solid-liquid separation, the solid can be recovered by filtering the liquid, and the solid can be dissolved in water to obtain a concentrated working medium B. When dissolving the solid, the temperature of the working medium B is lowered below a predetermined temperature by, for example, exposing the working medium B to the atmosphere, thereby dissolving the solid.

In addition, when liquid-liquid separation occurs, the upper phase or lower phase is recovered using a liquid-liquid separation device such as decantation or a separating funnel, and the phase containing a high concentration of amine compound is dissolved in water. A concentrated working medium B can be obtained. When the phase containing the high-concentration amine compound is dissolved in water, the temperature of the working medium B is lowered below a predetermined temperature by, for example, exposing the working medium B to the atmosphere, and the phase containing the high-concentration amine compound is dissolved in water. Dissolve.

Concentration of the working medium B is facilitated when the solubility of the amine compound in water varies greatly with temperature. Therefore, it is preferable to use an amine compound whose solubility in water at a temperature lower than a predetermined temperature is at least four times higher than the solubility in water at a temperature equal to or higher than a predetermined temperature.

The solute contained in the working medium B is a compound whose affinity for water changes depending on the temperature. The working medium B of the embodiment has a high permeation flux (Jw L /m ² h) can be generated. A specific amine compound is a compound represented by chemical formula (1) or (2). The structure of the compound is identified by 1H-NMR, 13C-NMR analysis.

R1, R2, R3 and R4 in the chemical formula (1) are linear or branched alkyl chains having 1 to 5 carbon chains and optionally contain hydroxyl groups and/or halogens. The halogen in the amine compounds of chemical formulas (1) and (2) is any one of Cl, Br and F.

Specific compounds represented by the chemical formula (1) include ethyl 4-{3-[4-(ethoxycarbonyl)piperazin-1-yl]propyl}piperazine-1-carboxylate, propyl 4-{3-[ Any one or more amine compounds from the group consisting of 4-(propoxycarbonyl)piperazin-1-yl]propyl}piperazine-1-carboxylate are preferred.

As a specific compound represented by the chemical formula (2), 1,1'-(1,3-propanediyl)bis-pyrrolidine is preferable.

The concentrations of the compounds represented by the chemical formulas (1) and (2), which are solutes in the working medium, depend on the concentration of the solutes in the water to be treated and the characteristics of the compounds represented by the chemical formulas (1) and (2). should be adjusted accordingly. Generally, the concentration of the amine compound in the working medium is desirably 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, if there is a problem such as an increase in viscosity, the concentration should be lowered.

Incidentally, carbon dioxide introduction means may be provided in the concentrator 2 or the second chamber 14 of FIG. By introducing carbon dioxide into the working medium B and ionizing it, the medium can be further improved in inducing osmotic pressure. As a means for introducing carbon dioxide, a carbon dioxide bubbling device or the like may be used, or dry ice (solid carbon dioxide) may be introduced into the working medium B. As the carbon dioxide used in the carbon dioxide introduction means, a gas obtained by refining carbon dioxide such as in the exhaust gas of a power plant using fossil fuel may be used.

Moreover, although the example in which the working medium B becomes a one-phase aqueous solution is shown when the temperature of the working medium B drops below the predetermined temperature, the working medium B does not undergo phase separation even when the temperature of the working medium B drops below the predetermined temperature. It may be as it is.

The concentrations of the compounds represented by the chemical formulas (1) and (2), which are solutes in the working medium, depend on the concentration of the solutes in the water to be treated and the characteristics of the compounds represented by the chemical formulas (1) and (2). should be adjusted accordingly. Generally, the concentration of the amine compound in the working medium is desirably 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, if there is a problem such as an increase in viscosity, the concentration should be lowered. Moreover, the same effect can be obtained not only with the compounds represented by the chemical formulas (1) and (2), but also with other compounds that undergo phase separation at temperature.

Therefore, in the embodiment, it is possible to provide a water treatment system and a working medium B for the water treatment system that can efficiently perform treatments such as desalination and concentration of the water A to be treated and that can be operated at low running costs. The water treatment system of the embodiment further has a rotating body, and the induction of osmotic pressure causes a water flow from the second chamber 14 toward the concentrator 2 (that is, a water flow from the concentrator 2 toward the second chamber 14). is generated), and it is also preferable to use it as a water treatment system that generates electricity by rotating the rotating body with the water flow. For example, the rotating body is provided in the second chamber 14, the concentrator 2, or the like.

(Second embodiment)
Next, a desalination system, which is one example of a 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 A to be treated, the second chamber 14, the working medium B, and the permeable membrane 12 are common to those of the first and second embodiments. 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. Although the reference numerals for the water to be treated, the working medium, and the water in the water treatment system are not shown in FIG. Since the second embodiment is a desalination system, the water to be treated A is salt water. A and the like are used.

The desalination system 200 comprises an osmotic pressure generator 1 , a concentrator 2 , a concentrated working medium tank 3 , a purified water tank 4 and a reverse osmosis membrane separator 5 . The osmotic pressure generator 1, the concentrator 2, the reverse osmosis membrane separator 5, and the concentrated working medium tank 3 are connected in this order to form a loop. An osmotic pressure-inducing working medium B circulates through this loop. That is, the working medium B circulates through the osmotic pressure generator 1, the concentrator 2, the reverse osmosis membrane separator 5, and the concentrated working medium tank 3 in this order. Note that up and down are the directions shown in the drawing, for example, the concentrated working medium tank 3 is above the concentrator 2 and the osmotic pressure generator 1 is on the left side of the reverse osmosis membrane separator 5. .

The to-be-treated water tank 15 is connected through a pipeline 101a to the upper portion of the processing container 10 where the first chamber 13 is located. 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 vessel where the first chamber 13 is located.

The concentrator 2 is connected through a pipeline 101e to the lower portion of the first processing container where the second chamber 14 is located. Furthermore, the concentrator 2 is connected with a concentrated working medium tank 3 through a pipeline 101d. A third pump 18 is provided in the pipeline 101d. A pipeline 101f is connected to the upper portion of the second processing vessel 21 where the third chamber 53 is located, and a pipeline 101g is connected to the lower portion of the second processing vessel 21 where the third chamber 53 is located. A third pump 18 is provided in the pipeline 101e.

The concentrated working medium tank 3 is connected through a pipeline 101c to the top of the first processing vessel where the second chamber 13 is located. A second pump 17 is provided in the pipeline 101c.

Purified water tank 4 is connected to reverse osmosis membrane separator 5 through pipeline 101h. The purified water tank 4 is connected to a pipeline 101i for sending out and collecting the purified water in the purified water tank 4 to the outside. The on-off valve 41 is provided in the pipeline 101i. For example, it is opened when the purified water in the purified water tank 4 exceeds a certain amount. When the reverse osmosis membrane separator 5 is omitted, the concentrator 2 and the purified water tank are connected through the pipeline 101h.

The reverse osmosis membrane separator 5 includes, for example, an airtight second processing vessel 51 . The second processing vessel 51 is partitioned, for example, horizontally by a reverse osmosis membrane (RO membrane or NF membrane) 52, and has a third chamber 53 on the left side and a fourth chamber 54 on the right side, respectively. It is connected to the purified water tank 4 through a pipeline 101i. The purified water tank 4 stores water (purified water) that has passed through the reverse osmosis membrane 52 and moved to the fourth chamber when the working medium B was concentrated.

Next, the desalting operation by the desalting system 200 shown in FIG. 2 will be described.

The first pump 16 is driven to supply the water to be treated A (eg, seawater) from the water to be treated tank 15 into the first chamber 13 of the osmotic pressure generator 1 through the pipeline 101a. Around the same time as the seawater is supplied, the second pump 17 is driven to supply the concentrated working medium B from the concentrated working medium tank 3 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 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 permeates 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 or second embodiment and exhibits a high osmotic effect. Therefore, when the water in the seawater in the first chamber 13 permeates the permeable membrane 12 and moves to the concentrated working medium B in the second chamber 14, a high permeation flux is generated. As a result, most of the water in the seawater in the first chamber 13 can be moved to the concentrated working medium B in the second chamber 14, and highly efficient desalination can be performed to extract water (pure water) from salt water.

In the osmotic pressure generator 1, water in seawater moves from the first chamber 13 to the concentrated working medium B in the second chamber 14, whereby the seawater is discharged from the first chamber 13 as concentrated seawater through the pipeline 101b, The concentrated working medium B is diluted with the displaced water. When the water treatment system of the embodiment concentrates the liquid to be treated A, waste water discharged through the pipeline 101b is collected.

The diluted working medium B in the second chamber 14 is delivered to the concentrator 2 through pipeline 101e. In the concentrator 2, the diluted working medium B is heated. The heated working medium B undergoes phase separation. The phase-separated working medium B is subjected to solid-liquid separation or liquid-liquid separation to recover water. The collected water moves to the third chamber 53 of the reverse osmosis membrane separator 5 through the pipeline 101f. The water that has moved to the third chamber 53 may contain a small amount of the amine compound used as the solute, which is concentrated by the reverse osmosis membrane separator 5 . The water enriched with amine compounds is mixed with concentrated working medium B through pipeline 101g. The purified water moved to the fourth chamber 4 by the reverse osmosis membrane separator 5 moves to the purified water tank 4 through the pipeline 101h.

In the concentrator 2, the concentrated working medium B is cooled or cooled by mixing it with any water, and the amine compound is dissolved in water again. The concentrated working medium B, which has become an aqueous amine solution, is delivered from the concentrator 2 to the concentrated working medium tank 3 . The concentrated working medium B in the concentrated working medium tank 3 is supplied into the second chamber 14 of the osmotic pressure generator 1 by driving the second pump 17, and water (pure water) is extracted from the salt water as described above. Used for desalination.

On the other hand, the water (pure water) that has moved to the fourth chamber 54 is delivered to the pure water tank 4 through the pipeline 101h. When the amount of water in the purified water tank 4 exceeds a certain amount, the on-off valve 41 is opened and the water is sent outside through the pipeline 101i to recover the water.

Therefore, it is possible to provide a desalination system that can efficiently desalinate seawater (recover pure water) and that can be operated at low running costs. Such a system can be operated at a low running cost even in a water treatment system that performs concentration.

In the desalination system 200 shown in FIG. 2, the osmotic pressure generator forms the first chamber 13 and the second chamber 14 by horizontally dividing the first processing container by the osmotic membrane. The first chamber 13 and the second chamber 14 may be formed by partitioning vertically with a permeable membrane.

When the solute concentration of the working medium B is lowered 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. 2, the concentration of the diluted working medium B is not limited to the case where it is performed by the reverse osmosis membrane separator 5 equipped with a reverse osmosis membrane (RO membrane, NF membrane). Any device may be used as long as it can be used.

(Third embodiment)
Next, an osmotic power generation system 300, which is one example of a water treatment system according to the third embodiment, will be described with reference to the schematic diagram shown in FIG. In FIG. 3, members similar to those in FIG. 2 are denoted by the same reference numerals, and descriptions thereof are omitted. The working medium used in the third embodiment is the working medium B of the first embodiment.

A water treatment system according to the third embodiment is a power generation system. The power generation system 300 includes an osmotic pressure generator 1 that generates water flow, and a rotor 6 that generates power using the water flow generated by the osmotic pressure generator 1 .

The osmotic power generation system 300 is divided into a first chamber 13 containing water, a second chamber 14 containing a working medium B (draw solution) that induces osmotic pressure, and the first chamber 13 and the second chamber 14. a permeable membrane 12 , a pressure exchanger 7 connected to the second chamber 14 , and a rotor 6 connected to the pressure exchanger 7 . According to such a water treatment system, the water in the first chamber 14 permeates the osmotic membrane 12 due to the osmotic pressure difference generated between the water in the first chamber 13 and the working medium B in the second chamber 14. Move to the working medium B in the second chamber 14 . The rotating body 6 is rotated by the water flow that accompanies the movement of the water to the working medium B to generate electricity.

The third embodiment exhibits a high osmotic pressure inducing action when the working medium B is an aqueous solution containing the solute of the embodiment. Therefore, when the water in the first chamber 13 permeates the permeable membrane 12 and moves to the working medium B in the second chamber 14, 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 6 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 6 to generate power and that can be operated at low running costs.

A turbine or a water wheel, for example, can be used as the rotating body 6 .

In the osmotic pressure power generation system 300, the pressure exchanger 7 and the rotating body 6 are installed in the pipeline 101e connected to the lower part (working medium B outlet side) of the first processing container where the second chamber 14 of the osmotic pressure generator 1 is located. They are provided in this order along the flow direction of the working medium B. As shown in FIG. Further, in the pipeline 101c connecting the upper part of the first processing container where the second chamber 14 is located and the concentrated working medium tank 3, the portion of the pipeline 101c on the downstream side in the flow direction of the working medium B from the second pump 17 is It is connected via a pressure exchanger 7 to the upper part of the first processing vessel in which the second chamber 14 is located. That is, in the osmotic pressure generator 1, the diluted working medium B having a flux generated when water moves from the first chamber 13 through the osmotic membrane 12 to the second chamber 14 is located in the second chamber 14. It flows out from the lower part of the first processing vessel through a pipeline 101e provided with a pressure exchanger 7. As shown in FIG. During this time, the pipeline 101 c through which the concentrated working medium B flowing out of the concentrated working medium tank 3 flows passes through the pressure exchanger 7 . Therefore, the concentrated working medium B is pressure-exchanged with the diluted working medium B flowing out of the second chamber 14 in the pressure exchanger 7, the diluted working medium B lowers the pressure, and the concentrated working medium B flowing to the rotating body 6 is Increase pressure.

In addition, in the osmotic pressure power generation system 300, water is stored in the water tank 15 to be treated.

Next, power generation operation by the osmotic pressure power generation system 300 shown in FIG. 3 will be described. The first pump 16 is driven to supply water from the water tank 15 to be treated into the first chamber 13 of the osmotic pressure generator 1 through the pipeline 101a. Before or after supplying water, the second pump 17 is driven to supply the concentrated working medium B from the concentrated working medium tank 3 into the second chamber 14 of the osmotic pressure generator 1 through the pipeline 101c. The concentrated working medium B supplied to the second chamber 14 is sufficiently concentrated relative to the solvent-only water supplied to the first chamber 13 . Therefore, an osmotic pressure difference is generated between the water in the first chamber 13 and the concentrated working medium B in the second chamber 14 , and the water permeates the osmotic membrane 12 and moves into the second chamber 14 . At this time, the working medium B in the second chamber 14 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 13 permeates the permeable membrane 12 and moves to the working medium B in the second chamber 14, a high permeation flux is generated. As a result, much of the water in the first chamber 13 can be transferred to the concentrated working medium B in the second chamber 14, producing a diluted working medium B with a high pressure diluted with water. Water in the first chamber 13 is discharged through the pipeline 101b.

The diluted working medium B with high pressure in the second chamber 14 is delivered to the concentrator 2 through the pipeline 101e and stored. A pressure exchanger 7 and a rotating body 6 are provided in this order along the flow direction of the working medium B in the pipeline 101e.

Therefore, as described above, the pressure exchanger 7 has a concentrated working medium B flowing from the concentrated working medium tank 3 through the pipeline 101c and a high pressure flowing from the second chamber 14 (through the rotating body 6) through the pipeline 101e. There is a pressure exchange with the dilute working medium B, reducing the pressure of the dilute working medium B and increasing the pressure of the concentrated working medium B. Due to the pressure exchange, the diluted working medium B having an appropriate pressure flows to the rotating body 6, which is efficiently rotated to generate electricity. Also, the concentrated working medium B having an appropriate pressure is supplied to the second chamber 14 by pressure exchange.

In the concentrator 2, the working medium B is concentrated and purified by the reverse osmosis membrane separator 5 in the same manner as in the second embodiment, and the concentrated aqueous amine working medium B is stored in the concentrated working medium tank 3. .

Note that in the osmotic power generation system 300 shown in FIG. A first chamber 13 and a second chamber 14 may be formed by dividing the container into upper and lower parts by a permeable membrane.

In the osmotic pressure power generation system 300 shown in FIG. 3, the water in the first chamber 13 of the osmotic pressure generator 1 was delivered to the outside through the pipeline 101b. A loop of the water tank 15, the pipeline 101a, the first chamber 13 of the osmotic pressure generator 1 and the pipeline 101b may be made.

Examples are described below.

(Example 1)
Phase separation tests with ethyl 4-{3-[4-(ethoxycarbonyl)piperazin-1-yl]propyl}piperazine-1-carboxylate were performed as previously described. The results are shown in FIG. Although the phase separation rate differs depending on the concentration, separation was most efficient at 70°C at any concentration.

(Example 2)
Ethyl 4-{3-[4-(ethoxycarbonyl)piperazin-1-yl]propyl}piperazine-1-carboxylate 33 wt% was utilized as the working medium and a forward osmosis test was performed as follows. A CTA-ES membrane manufactured by HTI was set in the FO cell, pure water was put on the active side of the membrane as water to be treated, and then a working medium was put on the support layer side. The time when the working medium was completely added was defined as 0 minutes, and the mixture was allowed to stand still 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 water to be treated after the test was measured with a total organic carbon meter, and the loss of solute (Js) was calculated. Table 1 shows the results.

(Example 3)
Same as Example 2, except that 33 wt% ethyl 4-{3-[4-(ethoxycarbonyl)piperazin-1-yl]propyl}piperazine-1-carboxylate bubbling 100% CO2 gas was used as the working medium. A similar test was conducted. Table 1 shows the results.

(Example 4)
The test was conducted as in Example 2, except that 33 wt% of 1,1'-(1,3-propanediyl)bis-pyrrolidine was utilized as the working medium. Table 1 shows the results.

(Example 5)
A test was conducted in the same manner as in Example 4, except that 33 wt % of 1,1'-(1,3-propanediyl)bis-pyrrolidine bubbled with 100% CO2 gas was used as the working medium. Table 1 shows the results.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, replacements, and modifications 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 scope of the invention described in the claims and equivalents thereof.

A ... water to be treated,
B... working medium,
C... Water 1... Osmotic pressure generator,
2... concentrator,
3 ... concentrated working medium tank,
4... Purified water tank,
5 ... reverse osmosis membrane separator,
6... Rotating body 7... Pressure exchanger 12... Osmotic membrane,
13 ... the first chamber,
14 ... second chamber,
15... Water tank to be treated,
16... 1st pump,
17... second pump,
18 ... third pump,
41 ... on-off valve,
51 ... second processing container,
52 ... reverse osmosis membrane (RO membrane, NF membrane),
53 ... third chamber,
54 ... fourth chamber,
100... Water treatment system,
101 pipeline,
200 ... desalination system,
300 Osmotic power generation system

Claims (8)

A working medium that contains water and an amine compound and undergoes phase separation when the temperature rises above a predetermined temperature,
The amine compounds include ethyl 4-{3-[4-(ethoxycarbonyl)piperazin-1-yl]propyl}piperazine-1-carboxylate, propyl 4-{3-[4-(propoxycarbonyl)piperazine-1- yl]propyl}piperazine-1-carboxylate or 1,1′-(1,3-propanediyl)bis-pyrrolidine
Working medium for use in water treatment . The working medium for use in water treatment according to claim 1, wherein said phase separation is solid-liquid separation or liquid-liquid separation. 3. The working medium for use in water treatment according to claim 1 or 2, which turns into a one-phase aqueous solution when the temperature drops below the predetermined temperature. The working medium for use in water treatment according to any one of claims 1 to 3, wherein the concentration of the amine compound in the working medium for use in water treatment is 10% by mass or more and 70% by mass or less. A first chamber containing water to be treated, a second chamber containing a working medium for use in water treatment according to any one of claims 1 to 4 that induces osmotic pressure, and the first chamber. A water treatment system comprising an osmotic pressure generator comprising an osmotic membrane defining the second chamber, and a concentrator comprising heating means for heating the working medium. 6. The water treatment system according to claim 5, further comprising a rotating body, wherein the osmotic pressure is induced to generate a water flow, and the water flow rotates the rotating body to generate electricity. 7. The water treatment system of claim 6, wherein said water flow is from said second chamber to said concentrator. 8. A water treatment system according to claim 6 or 7, wherein the water flow is directed from the concentrator to the second chamber.

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