Semipermeable membrane element and solvent-driven module

Abstract

To provide a semipermeable membrane element and a solvent-driven module that can easily separate a solvent drawn out from a target solution into a drive solution through a semipermeable membrane from the drive solution in solution treatment by the FO method.SOLUTION: One aspect of the present invention is a semipermeable membrane element for pushing out a solvent contained in a target solution through a semipermeable membrane by pressure, the semipermeable membrane element comprising a semipermeable membrane member having a first semipermeable membrane at least in a portion thereof, and an elastic member having an elastic membrane at least in a portion thereof and being arranged integrally connected to or separately arranged with respect to the semipermeable membrane member. Another aspect of the present invention is a solvent-driven module comprising a drive solution chamber that contains a drive solution and is sealably provided, a second semipermeable membrane that is connected to the drive solution chamber, contacts with the target solution on one side and contacts with the drive solution on the other side, and the semipermeable membrane element that is connected to the drive solution chamber, where the first semipermeable membrane of the semipermeable membrane element is in contact with the drive solution on the one side.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a semipermeable membrane element and a solvent-driven module used for solution treatment, for example, to a semipermeable membrane element and a solvent-driven module used in desalinating seawater. [Background technology]

[0002] In recent years, water production using seawater desalination technology has expanded rapidly due to the rising demand for water caused by global warming and population growth. The seawater desalination technologies currently in practical use can be broadly divided into two methods: the evaporation method, which uses heat, and the reverse osmosis (RO) method, which uses semipermeable membranes. Of these, the latter, the RO method, is the mainstream in terms of energy efficiency.

[0003] In the RO method, water is forcibly pushed in the opposite direction to forward osmosis at a high pressure greater than the osmotic pressure difference, which requires a lot of external energy. Therefore, forward osmosis (FO), which utilizes the spontaneous water movement phenomenon based on the osmotic pressure difference, has attracted attention as a more energy-efficient method.

[0004] A typical example of the FO method uses a liquid called a driving solution as a driving medium that draws fresh water from seawater through a semipermeable membrane. As mentioned above, the FO method is a spontaneous water movement phenomenon based on an osmotic pressure difference, but the reason it is called a "driving solution" in the FO method is because it looks as if the driving solution draws water from seawater.

[0005] FIG. 11 is a schematic diagram of a desalination system using a conventional driving solution. 11, a solvent containing a high concentration of solute particles (driving microparticles) designed to have a sufficiently high osmotic pressure relative to seawater L1 is used for driving solution 810. A treatment tank 815 is connected to solvent-driven module 800a filled with driving solution 810. When seawater L1, from which unwanted substances such as garbage and impurities have been removed in pretreatment tank 816, is supplied to treatment tank 815 by pump 817a, water moves (permeates) from the seawater side (low osmotic pressure side) to the driving solution 810 side (high osmotic pressure side) through semipermeable membrane 820 due to the osmotic pressure difference between seawater L1 and driving solution 810.

[0006] This permeate (treated water L2) is absorbed into the drive solution 810, so in order to use the water as fresh water, a separate drive solution separation / adjustment tank 819 is installed, and treated water L2 (fresh water) is separated from the drive solution 810 and stored in a treated water storage tank 818. Meanwhile, the drive solution 810 after separation is adjusted in concentration, and is circulated and reused by a pump 817b. Various methods have been proposed as separation methods that utilize external energy such as heat, pressure, electricity, and magnetism in combination with a separation membrane (see, for example, Patent Document 1 and Non-Patent Document 1).

[0007] Recently, an FO method has been proposed that does not require external energy when separating the permeate from the driving solution by performing pressure filtration using an increase in the internal pressure of a driving solution tank in which the driving solution is stored (Non-Patent Document 2).

[0008] FIG. 12 is a schematic diagram of a desalination system using a conventional driving solution and utilizing internal pressure. In the desalination system shown in FIG. 12, an aqueous solution using polymeric polystyrene sulfonate (PSS) as driving particles is used as a driving solution 810. A treatment tank 815 is connected to a solvent-driven module 800b filled with the driving solution 810. When seawater L1 from which unnecessary substances such as garbage and impurities have been removed in a pretreatment tank 816 is supplied to the treatment tank 815 by a pump 817a, water moves (permeates) from the seawater side (low osmotic pressure side) to the driving solution 810 side (high osmotic pressure side) through a semipermeable membrane 820 based on the osmotic pressure difference between the seawater L1 and the driving solution 810. Up to this point, it is the same as the conventional desalination system shown in FIG. 11, but this system is different in that no external energy is required to separate fresh water from the driving solution.

[0009] That is, in the desalination system shown in FIG. 12, the internal pressure of the driving solution tank 830 increases due to an increase in the permeate water that moves from the treatment tank 815 side to the driving solution 810 side through the semipermeable membrane 820, and the driving solution is pressurized and filtered by the separation membrane 840 connected to the driving solution tank 830 due to this increase in internal pressure, and treated water L2 (fresh water) is separated from the driving solution 810 and stored in the treated water storage tank 818. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2016-087494 A [Non-patent literature]

[0011] [Non-Patent Document 1] Aondohemba Aende, Jabbar Gardy and Ali Hassanpour, “Seawater Desalination: A Review of Forward Osmosis Technique, Its Challenges, and Future Prospects,” Online Journal Processes 2020, Vol. 8, No. 8 901, pp. 1-36, [Retrieved June 22, 2023], Internet<https: / / www.mdpi.com / 2227-9717 / 8 / 8 / 901> [Non-Patent Document 2] Sung-Ju Im, Jungwon Choi, Sanghyun Jeong and Am Jang, “New concept of pump-less forward osmosis (FO) and low-pressure membrane (LPM) process,” Online Journal Scientific Reports, Vol. 7, pp. 1-6 (2017), [Retrieved June 22, 2023], Internet<https: / / www.nature.com / articles / s41598-017-15274-z> [Non-Patent Document 3] Agriculture and Livestock Industries Corporation, Sugar Information, [Retrieved June 22, 2023], Internet<https / / sugar.alic.go.japan / japan / view / jv_0005c.htm> [Non-Patent Document 4] Keiji Sasuga et al., "About agar and agarose for electrophoresis", THE CHEMICAL TIMES, Vol. 222, No. 4, pp. 8-14 (2011), [Retrieved June 22, 2023], Internet<https / / www.kanto.co.jp / dcms_media / other / backno7_pdf38.pdf> Summary of the Invention [Problem to be solved by the invention]

[0012] As mentioned above, the FO method usually uses a working solution as the driving medium, and requires external energy such as heat, pressure, electricity, and magnetism to separate fresh water from the working solution. In addition, many working solutions contain harmful substances, which may flow back through the semipermeable membrane and leak into the seawater, causing environmental pollution.

[0013] In addition, the recently proposed FO method that uses internal pressure and a driving solution uses a separation membrane to separate the driving particles and treated water (freshwater) from the driving solution by pressure filtration, and uses large-particle-sized polymers as the driving particles to increase the separation efficiency during pressure filtration. However, polymers generally have low solubility in water, making it difficult to prepare a high-concentration driving solution, and therefore it is difficult to ensure a sufficient osmotic pressure difference for practical seawater desalination.

[0014] An object of the present invention is to provide a semipermeable membrane element and a solvent-driven module that can easily separate, from a driving solution, a solvent drawn from a target solution into a driving solution via a semipermeable membrane in solution treatment by the FO method. [Means for solving the problem]

[0015] One aspect of the present invention is a semipermeable membrane element for pushing out a solvent contained in a target solution through a semipermeable membrane by pressure, the semipermeable membrane element comprising a semipermeable membrane member having a first semipermeable membrane on at least a portion thereof, and an elastic member that is integrally connected to or separately arranged with respect to the semipermeable membrane member and has an elastic membrane on at least a portion thereof.

[0016] With this configuration, the first semipermeable membrane suppresses the movement of water due to forward osmosis, and when the first semipermeable membrane is pressurized from the high osmotic pressure side, the elastic member is elastically deformed to adjust the pressure, thereby allowing water to move from the high osmotic pressure side to the low osmotic pressure side.

[0017] In the above-mentioned semipermeable membrane element, the first semipermeable membrane preferably has one or more types of layer structure and has a thickness equal to or greater than the permeation limit at which forward osmosis due to osmotic pressure difference does not occur (non-permeable semipermeable membrane). This allows the use of semipermeable membranes used in conventional FO or RO methods, enhancing the practicality of the present invention. In addition, forward osmosis due to osmotic pressure difference, i.e., the movement of water from the low osmotic pressure side to the high osmotic pressure side, is suppressed, and conversely, water can move from the high osmotic pressure side to the low osmotic pressure side by applying pressure.

[0018] In the above-mentioned semipermeable membrane element, the elastic membrane may be formed of a material having rubber elasticity, whereby the internal pressure of the driving solution chamber is increased while the volume of the driving solution chamber is increased so as to accommodate a large amount of solvent drawn from the target solution through the semipermeable membrane, and further, the increase in internal pressure makes it possible to push out the solvent from the driving solution through the semipermeable membrane having a thickness equal to or greater than the permeation limit.

[0019] Another aspect of the present invention is a solvent-driven module having a function of drawing out a solvent contained in a target solution through a semipermeable membrane by using an osmotic pressure difference, the solvent-driven module comprising a drive solution chamber that contains a drive solution and is sealably arranged, a second semipermeable membrane connected to the drive solution chamber and in contact with the target solution on one side and with the drive solution on the other side, and the above-mentioned semipermeable membrane element connected to the drive solution chamber, wherein the first semipermeable membrane of the semipermeable membrane element is in contact with the drive solution on one side.

[0020] According to this configuration, water moves to the drive solution chamber by forward osmosis in the second semipermeable membrane. On the other hand, since forward osmosis is suppressed in the first semipermeable membrane, the internal pressure of the drive solution chamber automatically increases due to the water that moves to the drive solution chamber through the second semipermeable membrane. Since the semipermeable membrane element provided with the first semipermeable membrane is provided with an elastic member having an elastic membrane, the elastic membrane is elastically deformed by the increase in the internal pressure of the drive solution chamber, thereby moving water to the drive solution chamber and adjusting the increase in internal pressure. The automatic increase in the internal pressure of the drive solution chamber moves water in the drive solution chamber through the first semipermeable membrane. In other words, it is possible to draw out the solvent contained in the target solution into the drive solution and separate it from the drive solution without requiring external energy, and to steadily move the treated water through the first semipermeable membrane.

[0021] In the above-mentioned solvent-driven module, flanges for detachably connecting each part may be provided between the second semipermeable membrane and the driving solution chamber, and between the driving solution chamber and the semipermeable membrane element, thereby making it possible to easily connect / disconnect each of the components, resulting in a highly practical solvent-driven module. Effect of the Invention

[0022] According to the present invention, it is possible to provide a semipermeable membrane element and a solvent-driven module that can easily separate the solvent extracted from the target solution into the driving solution from the driving solution in solution treatment by the FO method. [Brief description of the drawings]

[0023] [Figure 1A] FIG. 2 is a schematic plan view illustrating the configuration of a semipermeable membrane element. [Figure 1B] FIG. 2 is a schematic cross-sectional view illustrating the configuration of a semipermeable membrane element. [Figure 1C] FIG. 2 is a schematic cross-sectional view illustrating the configuration of a semipermeable membrane element. [Figure 1D] FIG. 2 is a schematic cross-sectional view illustrating the configuration of a semipermeable membrane element. [Figure 1E] FIG. 11 is a schematic plan view illustrating another configuration of the semipermeable membrane element. [Figure 1F] FIG. 11 is a schematic cross-sectional view illustrating another configuration of a semipermeable membrane element. [Figure 1G] FIG. 11 is a schematic cross-sectional view illustrating another configuration of a semipermeable membrane element. [Diagram 2] FIG. 1 is a diagram illustrating the relationship between membrane thickness and permeation rate in a forward osmosis experiment of a semipermeable membrane. [Figure 3A] FIG. 2 is a schematic diagram for explaining the state of permeation depending on the membrane thickness in a forward osmosis experiment of a semipermeable membrane. [Figure 3B] FIG. 2 is a schematic diagram for explaining the state of permeation depending on the membrane thickness in a forward osmosis experiment of a semipermeable membrane. [Figure 4] FIG. 1 is a schematic diagram illustrating a case where pressure is applied to a semipermeable membrane having a thickness equal to or greater than the permeation limit. [Diagram 5] FIG. 2 is a schematic diagram illustrating a solvent-driven module. [Figure 6] FIG. 1 is a schematic diagram illustrating a solution processing system (part 1). [Figure 7] FIG. 2 is a schematic diagram illustrating a solution processing system (part 2). [Figure 8] FIG. 13 is a schematic diagram illustrating a solution processing system (part 3). [Figure 9] FIG. 13 is a schematic diagram illustrating a solution processing system (part 4). [Figure 10] FIG. 5 is a schematic diagram illustrating a solution processing system (part 5). [Figure 11] FIG. 1 is a schematic diagram of a seawater desalination system using a driving solution. [Figure 12] FIG. 1 is a schematic diagram of a seawater desalination system using an internal pressure and a driving solution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same members are designated by the same reference numerals, and the description of members that have already been described will be omitted as appropriate.

[0025] (First embodiment: semipermeable membrane element) First, the semipermeable membrane element according to the first embodiment will be described. FIG. 1A is a schematic plan view illustrating the configuration of a semipermeable membrane element. Figures 1B to 1D are schematic cross-sectional views illustrating the configuration of a semipermeable membrane element, each showing a schematic cross-sectional view taken along line X1-X1' shown in Figure 1A.

[0026] 1A, the semipermeable membrane element 1 according to this embodiment comprises a semipermeable membrane member 11 having a first semipermeable membrane 10 at least in a portion thereof, and an elastic member 16 having an elastic membrane 15 at least in a portion thereof, which is integrally connected to the semipermeable membrane member 11. The semipermeable membrane member 11 may be entirely composed of the first semipermeable membrane 10, or may be configured to include only the first semipermeable membrane 10 in a portion thereof. In this embodiment, the semipermeable membrane member 11 comprises the first semipermeable membrane 10 and a frame portion 13 that holds the periphery of the first semipermeable membrane 10. The elastic membrane 15 is an example of an elastic member.

[0027] As shown in Fig. 1A, in the semipermeable membrane element 1 of the integrally connected arrangement structure according to this embodiment, an opening 12 for solvent permeation is provided in the center of the semipermeable membrane element 1. The opening 12 is provided inside the frame portion 13, in the center of the elastic membrane 15. The elastic membrane 15 is joined to a joint 14 around the periphery of the semipermeable membrane member. The elastic membrane 15 is provided so as to extend outward from the joint 14. The outer shape of the semipermeable membrane element 1 according to this embodiment in a plan view is rectangular, and the opening 12 is also provided in a rectangular shape, but is not limited to this shape.

[0028] 1B to 1D, there are at least three types of semipermeable membrane elements 1, namely, semipermeable membrane elements 1A, 1B, and 1C. That is, the semipermeable membrane elements 1A, 1B, and 1C each have, as the first semipermeable membrane 10, a single-layer configuration of semipermeable membrane 10a, a two-layer configuration of semipermeable membrane 10a and semipermeable membrane 10b, and a three-layer configuration of semipermeable membrane 10a, semipermeable membrane 10b, and semipermeable membrane 10c. In each configuration of the first semipermeable membrane 10, an elastic membrane 15 is connected to the semipermeable membrane member 11. Note that the semipermeable membrane configuration of the first semipermeable membrane 10 is not limited to the above three types.

[0029] As the first semipermeable membrane 10, a cellulose-based semipermeable membrane such as cellophane (cellulose) or cellulose acetate, or a polyamide-based semipermeable membrane such as aromatic polyamide, which have been conventionally used in the RO method or FO method, can be used. In addition, a natural polymer agar (main component agarose) gel membrane can also be used.

[0030] In this embodiment, as described later, a thick membrane of at least several hundred microns is required, but the cellulose membranes and polyamide membranes used in the RO and FO methods are usually thin membranes of several microns to several tens of microns in order to increase separation efficiency, and are difficult to apply alone. On the other hand, agar gel membranes can be easily prepared to have a thickness of the order of millimeters, and can be applied alone.

[0031] Furthermore, a material that has a low elastic modulus, stretches more easily than the first semipermeable membrane 10, can accommodate a large amount of liquid, and can pressurize the liquid with high internal stress (restoring force) is suitable for the elastic membrane 15. For example, a material having rubber elasticity used in balloons, diaphragm pumps, etc., that is, a sheet of rubber (silicone, nitrile, urethane, etc.) is suitable for the elastic membrane 15.

[0032] Furthermore, the semipermeable membrane member 11 and the elastic membrane 15 can be joined together by a bonding method using an adhesive or a pressure bonding method using a spring, a screw, or the like.

[0033] Each of the semipermeable membrane elements 1A, 1B, and 1C is an element for pushing out the solvent contained in the drive solution by pressure difference through the first semipermeable membrane 10. By mounting the semipermeable membrane elements 1A, 1B, and 1C in a solvent-driven module (to be described later) and incorporating the solvent-driven module into a solution processing system, it becomes possible to separate the solvent from the target solution without using external energy. The principle of this will be described later.

[0034] FIG. 1E is a schematic plan view illustrating another configuration of the semipermeable membrane element. 1F and 1G are schematic cross-sectional views illustrating other configurations of the semipermeable membrane element. Fig. 1F shows a schematic cross-sectional view of X2-X2' shown in Fig. 1E, and Fig. 1G shows a schematic cross-sectional view of X3-X3' shown in Fig. 1E. 1E, a semipermeable membrane element 1D according to another configuration comprises a semipermeable membrane member 11 having a first semipermeable membrane 10 at least in a portion thereof, and an elastic member 16 having an elastic membrane 15 in at least a portion thereof arranged separately from the semipermeable membrane member 11. The semipermeable membrane member 11 may be entirely composed of the first semipermeable membrane 10, or may be configured to include only the first semipermeable membrane 10 in a portion thereof.

[0035] As shown in Fig. 1E and Fig. 1F, the semipermeable membrane member 11 of the semipermeable membrane element 1D of the separated arrangement structure is configured to include a first semipermeable membrane 10 and a frame portion 13 that holds the periphery of the first semipermeable membrane 10. An opening 12 for solvent permeation is provided in the center of the semipermeable membrane member 11. The opening 12 is provided inside the frame portion 13 and in the center of the first semipermeable membrane 10. The first semipermeable membrane 10 is joined to the frame portion 13 at a joint portion 14 around the periphery of the first semipermeable membrane 10. The semipermeable membrane member 11 is provided so as to extend outward from the joint portion 14. The outer shape of the semipermeable membrane member 11 of the semipermeable membrane element 1D according to this embodiment is rectangular in plan view, and the opening portion 12 is also provided in a rectangular shape, but is not limited to this shape.

[0036] As shown in Fig. 1F, for example, the first semipermeable membrane 10 of the semipermeable membrane member 11 has a single-layer structure of a semipermeable membrane 10a. The semipermeable membrane member 11 may have a two-layer structure of a semipermeable membrane 10a and a semipermeable membrane 10b as shown in Fig. 1C, or a three-layer structure of a semipermeable membrane 10a, a semipermeable membrane 10b, and a semipermeable membrane 10c as shown in Fig. 1D. The semipermeable membrane structure of the first semipermeable membrane 10 is not limited to the above three types.

[0037] 1E and 1G, the elastic member 16 of the semipermeable membrane element 1D of the separated arrangement structure is configured to include an elastic membrane 15 and a frame portion 18 that holds the periphery of the elastic membrane 15. An opening 17 for adjusting the internal pressure of the driving solution chamber is provided in the center of the elastic member 16. The opening 17 is provided inside the frame portion 18 and in the center of the elastic membrane 15. The elastic membrane 15 is joined to the frame portion 18 at joints 19 around the periphery of the elastic membrane 15, and the elastic member 16 is provided so as to extend outward from the joints 19. The outer shape of the elastic member 16 in a plan view of the semipermeable membrane element 1D according to this embodiment is rectangular, and the opening 17 is also provided in a rectangular shape, but is not limited to this shape.

[0038] In the semipermeable membrane element 1D, the elastic member 16 is disposed separately from the semipermeable membrane member 11. Here, "disposed separately" means that the elastic member 16 is disposed in a state in which it is configured separately from the semipermeable membrane member 11. The elastic member 16 may be connected to the semipermeable membrane member 11 by a connecting member (not shown) (for example, a connecting member connecting the frame portion 13 and the frame portion 18), the frame portion 13 may be connected to the frame portion 18, or the elastic member 16 may not be connected to the semipermeable membrane member 11. Here, the semipermeable membrane element 1D in which the elastic member 16 and the semipermeable membrane member 11 are configured separately and connected will be referred to as a semipermeable membrane element 1D-1, and the semipermeable membrane element 1D that is not connected will be referred to as a semipermeable membrane element 1D-2. When the semipermeable membrane element 1D-1 and the semipermeable membrane element 1D-2 are not to be distinguished from each other, they will be collectively referred to as a semipermeable membrane element 1D.

[0039] In addition, when joining between the first semipermeable membrane 10 and the frame portion 13, between the first semipermeable membrane 10 and the elastic membrane 15, between the elastic membrane 15 and the frame portion 18, between the elastic membrane 15 and the elastic member 16, and between each of the other components, a bonding method using an adhesive or a crimping method using a spring, screw, etc. can be applied.

[0040] <Forward osmosis experiment> Next, the principle of separating a solvent from a target solution by a semipermeable membrane element will be described. First, before describing the semipermeable membrane element according to this embodiment in detail, a forward osmosis experiment using a semipermeable membrane of a single layer structure will be described in order to explain the principle of the present invention. FIG. 2 is a diagram for explaining the relationship between membrane thickness and permeation rate in a forward osmosis experiment of a semipermeable membrane. In this experiment, a commercially available cellophane membrane (20 μm thick per sheet) was used as the semipermeable membrane, fresh water and a driving solution were placed on both sides of the cellophane membrane, and the change in the permeation rate (millimeters / hour, mm / h) of the permeating liquid (water) relative to the thickness of the cellophane membrane was obtained. Two types of driving solutions were prepared: sucrose water with a concentration of 50 weight percent (wt%) and saline solution with a concentration of 25 wt%. According to Non-Patent Document 3, the osmotic pressure of sucrose water with a concentration of 50 wt% is approximately 65 atmospheres, while the saline solution is estimated to be approximately 150 atmospheres. Therefore, the osmotic pressure difference with fresh water is approximately 65 atmospheres and approximately 150 atmospheres, respectively.

[0041] The graph shown by the plot of circles in Figure 2 shows the relationship between the membrane thickness and the permeation rate when a saline solution with a concentration of 25 wt% is used as the driving solution, and the graph shown by the plot of circles in Figure 2 shows the relationship between the membrane thickness and the permeation rate when a sucrose solution with a concentration of 50 wt% is used as the driving solution. As is clear from Figure 2, the permeation rate for both decreases almost inversely proportional to the membrane thickness, and at approximately 800 μm (equivalent to 40 cellophane membranes), the permeation rate becomes essentially 0 and permeation stops (permeation stopped state). This phenomenon suggests that in forward osmosis, there is a permeation limit at which permeation stops, regardless of the type of dissolved solute particles. In other words, normal forward osmosis occurs when the membrane thickness is below the permeation limit, but the forward osmosis phenomenon does not occur when the membrane thickness is above the permeation limit.

[0042] 3A and 3B are schematic diagrams for explaining the state of permeation depending on the membrane thickness in a forward osmosis experiment of a semipermeable membrane. Here, the state of a forward osmosis experiment of 50 wt% sucrose water is shown. Fig. 3A shows the state when a semipermeable membrane 31 with a membrane thickness below the permeation limit is used, and Fig. 3B shows the state when a semipermeable membrane 32 with a membrane thickness above the permeation limit is used.

[0043] In the case of using a semipermeable membrane 31 with a thickness below the permeation limit shown in Fig. 3A, water permeates from the freshwater La side (low osmotic pressure side) to the 50 wt% sucrose water Lb side (high osmotic pressure side) through the semipermeable membrane 31 due to an osmotic pressure difference of 65 atmospheres, and normal forward osmosis occurs. In this case, permeated water moves from both sides, but the total amount of permeation per unit time from the freshwater La side is greater than that from the 50 wt% sucrose water Lb side, and as a result, the liquid level on the 50 wt% sucrose water Lb side rises. In an actual desalination treatment system, the thinner the semipermeable membrane 31, the higher the flow rate, so a semipermeable membrane 31 that is thinner than the cellophane membrane (20 μm) used in the experiment in Fig. 2 is used.

[0044] On the other hand, in the case of using a semipermeable membrane 32 having a thickness equal to or greater than the permeation limit as shown in Fig. 3B, permeation stops in the semipermeable membrane 32 on both the fresh water La side and the 50 wt% sucrose water Lb side, no permeation phenomenon occurs, and the liquid level remains unchanged, as already described in Fig. 2. The reason for this permeation stop is presumably that as the water molecules move through the semipermeable membrane 32, they collide many times with the pore walls in the thick membrane, repeatedly causing friction, gradually losing kinetic energy, and finally stopping their progress.

[0045] Incidentally, in the case of the semipermeable membrane 32 having a thickness equal to or greater than the permeation limit shown in FIG. 3B, there have been no reports on how water moves when pressure is applied to the high osmotic pressure side (the 50 wt% sucrose water Lb side). The reverse osmosis method (RO method), which is currently the mainstream seawater desalination technology, is similar in that pressure is applied to the high osmotic pressure side. However, in the case of the RO method, a semipermeable membrane 31 having a thickness equal to or less than the permeation limit is used as shown in FIG. 3A, and is made as thin as possible to obtain a high flow rate. Furthermore, in the RO method, since the permeated water always flows from the low osmotic pressure side to the high osmotic pressure side through the semipermeable membrane 31, in order to make the water flow in the opposite direction, it is necessary to apply a high pressure (external pressure) at least equal to or greater than the osmotic pressure difference to eliminate the osmotic pressure difference. In the example shown in FIG. 3A, the osmotic pressure difference between fresh water La and 50 wt% sucrose water Lb is about 65 atmospheres, so a very large external pressure of at least 65 atmospheres or more is required to desalinate using the RO method.

[0046] FIG. 4 is a schematic diagram illustrating the case where pressure is applied to a semipermeable membrane having a thickness equal to or greater than the permeation limit. In the semipermeable membrane 32 with a thickness equal to or greater than the permeation limit, permeation stops (the state shown in FIG. 3B), and there is no inflow of permeated water from the low osmotic pressure side (the freshwater La side) to the high osmotic pressure side (the 50 wt% sucrose water Lb side). Therefore, it is expected that it will be possible to push water to the freshwater La side with a pressure considerably lower than the high pressure equal to or greater than the osmotic pressure difference required in the RO method.

[0047] Therefore, the inventors of the present application conducted an experiment in which pressure was applied to a semipermeable membrane 32 having a thickness equal to or greater than the permeation limit, as shown in Fig. 4, to push water from the 50 wt% sucrose water Lb side (high osmotic pressure side) to the fresh water La side (low osmotic pressure side) to obtain fresh water La. As a result, it was experimentally confirmed that water moves (permeates) from the 50 wt% sucrose water Lb side to the fresh water La side at a low pressure of 10 atm or less, which is lower than the osmotic pressure difference (65 atm) required in the RO method. Details will be described in the following <Semipermeable membrane element>, <Solvent-driven module>, and <Solution treatment system>.

[0048] <Semipermeable membrane element (part 1)> As shown in FIG. 1A and FIG. 1B, the semipermeable membrane element 1A is an example of an integrally connected arrangement structure, and includes a semipermeable membrane member 11 having a first semipermeable membrane 10 composed of a semipermeable membrane 10a of a single layer configuration, and an elastic membrane 15 connected to the semipermeable membrane member 11. In this embodiment, an agar gel is used as the semipermeable membrane 10a. As described in Non-Patent Document 4, agar is a natural polymer (main component agarose) produced from seaweed, and is known to become a three-dimensional mesh structure by gelation and become a semipermeable membrane. The mesh size, that is, the semipermeable membrane performance, can be adjusted by the gelation rate (the amount of agar charged during adjustment). Furthermore, it is possible to make the membrane thick in millimeters, and the first semipermeable membrane 10 having a membrane thickness aimed at being above the permeation limit can be easily produced (a specific production method will be described later).

[0049] On the other hand, a silicone rubber sheet (thickness: about 0.5 mm) was used for the elastic membrane 15, and an opening 12 was machined at the center as shown in Fig. 1A and Fig. 1B. Similarly, the frame portion 13 was machined using silicone rubber, and the elastic membrane 15 made of a silicone rubber sheet with the opening 12 machined thereon was adhered to it. The manufacturing method in this embodiment is one example, and the elastic membrane 15 and the frame portion 13 may be manufactured as an integral unit, or the frame portion 13 may be made of a material different from that of the elastic membrane 15. Furthermore, the thickness of the silicone rubber sheet, which is one example of the elastic membrane 15, is not limited to 0.5 mm, and may be other thicknesses.

[0050] The method for preparing and producing the agar gel membrane (semipermeable membrane 10a) will be described below. First, powdered agar was charged in a preparation container to a concentration of 2 wt% in purified water, and the contents were gradually heated to 80°C to 90°C to form a fluid sol state. The sol preparation was then gradually cooled, and poured into the silicone rubber frame 13 at a temperature above the gelling temperature of agar (35°C to 45°C), and cooled to room temperature to completely solidify (gel). This produced an agar gel semipermeable membrane 10a.

[0051] In this embodiment, a mesh sheet was placed on the opening 12 in the frame part 13 before injection to prevent leakage during injection. In addition, an absorbent cotton sheet (a nonwoven fabric of cellulose fibers) was placed on the mesh sheet and impregnated with the sol-like preparation to reinforce the agar gel membrane (semipermeable membrane 10a) (reinforcing effect of the agar gel by the cellulose fibers). After that, the upper peripheral part of the agar gel membrane (semipermeable membrane 10a) along the inner side surface of the frame part 13 was waterproofed with a sealant. The thickness of the agar gel membrane (semipermeable membrane 10a) produced was about 5 mm. This thickness was confirmed in the experiment of the <Solution Treatment System> described later to be sufficiently thicker than the permeation limit and to be a film thickness at which the forward osmosis phenomenon does not occur.

[0052] In this embodiment, agar gel is used for the semipermeable membrane 10a because it is easy to obtain a thickness thicker than the permeation limit, and other materials may be used as long as they can be made thicker. For example, as described above, all cellulose-based and polyamide-based semipermeable membranes used in the conventional FO and RO methods can be used. The agar concentration of 2 wt% is just an example, and other concentrations may be used.

[0053] The semipermeable membrane element 1A prepared as described above was attached to a solvent-driven module, which was then incorporated into a solution treatment system to carry out a desalination experiment, which will be described later in the sections "Solvent-driven module" and "Solution treatment system."

[0054] <Semipermeable membrane element (part 2)> As shown in Figures 1A and 1C, the semipermeable membrane element 1B is an example of an integrally connected arrangement structure, and includes a semipermeable membrane member 11 having a first semipermeable membrane 10 composed of a two-layered semipermeable membrane 10b (lower layer) / semipermeable membrane 10a (upper layer), and an elastic membrane 15 connected to the semipermeable membrane member 11. In this embodiment, a cellophane membrane (thickness 20 µm) was used for the lower semipermeable membrane 10b, and an agar gel membrane was used for the upper semipermeable membrane 10a. As with the semipermeable membrane element 1A, the elastic membrane 15 was made of a silicone rubber sheet (thickness about 0.5 mm) and was processed in the same manner.

[0055] The two-layer structure of cellophane membrane (semipermeable membrane 10b) / agar gel membrane (semipermeable membrane 10a) in the first semipermeable membrane 10 was prepared and produced by the following method. First, a cellophane membrane (semipermeable membrane 10b) cut to a predetermined size so as to cover the entire opening 12 was placed on the inner joint 14 of the silicone rubber frame 13 and adhered with an adhesive. Next, an agar gel membrane (semipermeable membrane 10a) was prepared on the cellophane membrane (semipermeable membrane 10b). The preparation and preparation of the agar gel membrane (semipermeable membrane 10a) were carried out in the same manner as in the case of the semipermeable membrane element 1A described above.

[0056] Thereafter, the upper peripheral portion of the agar gel membrane (semipermeable membrane 10a) was waterproofed with a sealant along the inner side surface of the frame portion 13. The total thickness of the two layers, the cellophane membrane (semipermeable membrane 10b) and the agar gel membrane (semipermeable membrane 10a), was approximately 5 mm. This thickness was confirmed in an experiment using a solution processing system described later as being sufficiently thicker than the permeation limit and not causing forward osmosis.

[0057] In this embodiment, agar gel is used for the semipermeable membrane 10a because a thickness thicker than the permeation limit can be easily obtained, and other materials may be used as long as the thickness can be increased. For example, as described above, all cellulose-based and polyamide-based semipermeable membranes used in the conventional FO method and RO method can be used. The same is true for the semipermeable membrane 10b. In principle, it is sufficient that the thickness of the first semipermeable membrane 10, which is the combination of the two layers, is equal to or greater than the permeation limit. In addition, a reinforcing material or a reinforcing support layer may be provided within or between the layers of the semipermeable membranes 10a and 10b. In addition, the thickness of the silicone rubber sheet, which is an example of the elastic membrane 15, is not limited to 0.5 mm, and may be other thicknesses.

[0058] The semipermeable membrane element 1B prepared as described above was attached to a solvent-driven module, which was then incorporated into a solution treatment system to carry out a desalination experiment, which will be described later in the sections "Solvent-driven module" and "Solution treatment system."

[0059] <Semipermeable membrane element (part 3)> As shown in Figures 1A and 1D, the semipermeable membrane element 1C is an example of an integrally connected structure, and includes a semipermeable membrane member 11 having a first semipermeable membrane 10 composed of a three-layered semipermeable membrane 10b (lower layer), a semipermeable membrane 10a (middle layer), and a semipermeable membrane 10c (upper layer), and an elastic membrane 15 connected to the semipermeable membrane member 11. In this embodiment, a cellophane membrane (thickness 20 μm) was used for the semipermeable membrane 10b, an agar gel membrane was used for the semipermeable membrane 10a, and a cellophane membrane (thickness 20 μm) was used for the semipermeable membrane 10c. As with the semipermeable membrane elements 1A and 1B, a silicone rubber sheet (thickness about 0.5 mm) was used for the elastic membrane 15, and similar processing was performed.

[0060] The three-layer structure of cellophane membrane (semipermeable membrane 10b) / agar gel membrane (semipermeable membrane 10a) / cellophane membrane (semipermeable membrane 10c) in the first semipermeable membrane 10 was prepared and produced by the following method. First, a cellophane membrane (semipermeable membrane 10b) cut to a predetermined size was placed on the joint 14 inside the silicone rubber frame 13 so as to cover the entire opening 12, and was adhered with an adhesive. Next, an agar gel membrane (semipermeable membrane 10a) was produced on the cellophane membrane (semipermeable membrane 10b). The preparation and production of the agar gel membrane (semipermeable membrane 10a) were carried out in the same manner as in the case of the above-mentioned semipermeable membrane elements 1A and 1B.

[0061] Thereafter, a cellophane membrane (semipermeable membrane 10c) cut to a predetermined size similar to the lower cellophane membrane was attached to the agar gel membrane (semipermeable membrane 10a), and the gap between the upper peripheral portion of the cellophane membrane (semipermeable membrane 10c) and the inner side surface of the frame portion 13 was waterproofed with a sealant. The total thickness of the three layers of the cellophane membrane (semipermeable membrane 10b), agar gel membrane (semipermeable membrane 10a), and cellophane membrane (semipermeable membrane 10c) was about 5 mm. This thickness was confirmed in an experiment using a solution processing system described later as being sufficiently thicker than the permeation limit and not causing forward osmosis.

[0062] In this embodiment, agar gel is used for the semipermeable membrane 10a because a thickness thicker than the permeation limit can be easily obtained, and other materials may be used as long as the thickness can be increased. For example, as described above, all cellulose-based and polyamide-based semipermeable membranes used in the conventional FO method and RO method can be used. The same is true for the semipermeable membranes 10b and 10c. In principle, it is sufficient that the thickness of the first semipermeable membrane 10, which is the combination of the three layers, is equal to or greater than the permeation limit. In addition, the semipermeable membranes 10a, 10b, and 10c may have a reinforcing material or a reinforcing support layer within or between the layers. In addition, the thickness of the silicone rubber sheet, which is an example of the elastic membrane 15, is not limited to 0.5 mm, and may have other thicknesses.

[0063] The semipermeable membrane element 1C prepared as described above was attached to a solvent-driven module, which was then incorporated into a solution treatment system to carry out a desalination experiment, which will be described later in the sections "Solvent-driven module" and "Solution treatment system."

[0064] <Semipermeable membrane element (part 4)> As shown in Figures 1E, 1F and 1G, the semipermeable membrane element 1D is an example of a separated arrangement structure, and includes a semipermeable membrane member 11 having a first semipermeable membrane 10 composed of a semipermeable membrane 10a having a single-layer structure, and an elastic member 16 having an elastic membrane 15 separated from the semipermeable membrane member 11. In this embodiment, a cellophane membrane (approximately 1 mm thick) was used as the semipermeable membrane 10a. This thickness is thicker than the permeation limit, and it was confirmed in the above-mentioned <Forward Osmosis Experiment> and the experiment of the <Solution Treatment System> described below that this thickness is a thickness at which forward osmosis does not occur.

[0065] As shown in FIG. 1E and FIG. 1F, an opening 12 is provided in the center of the cellophane membrane, and the cellophane membrane is fused and fixed at the joints 14 at the periphery using a resin material to prepare the frame portion 13. The preparation method in this embodiment is an example, and any membrane material other than the cellophane membrane can be used for the semipermeable membrane 10a, for example, any cellulose-based or polyamide-based semipermeable membrane used in the conventional FO method or RO method, as described above. As with the semipermeable membrane element having the integrally connected arrangement structure described above, the semipermeable membrane may have a multi-layer structure of multiple semipermeable membranes, and may have a reinforcing material or a reinforcing support layer between the layers. The frame portion 13 may be made of a material other than resin. In addition to the frame portion 13, resin, metal, and other members can be used to reinforce the frame portion 13 and to join it to the driving solution chamber 110, and these are also included in the semipermeable membrane member 11.

[0066] On the other hand, as shown in FIG. 1E and FIG. 1G, a silicone rubber sheet (about 0.5 mm thick) was used for the elastic membrane 15. As shown in FIG. 1E and FIG. 1G, an opening 17 was provided in the center, and a resin material was used to bond and fix the resin material at the joints 19 in the periphery to produce a frame portion 18, as in the case of the cellophane membrane described above. The production method in this embodiment is an example, and a membrane material other than the silicone rubber sheet may be used for the elastic membrane 15, and the frame portion 18 may be produced from a material other than resin. Furthermore, in addition to the frame portion 18, a member such as a resin or metal may be used for reinforcing the frame portion 18 or for joining the driving solution chamber 110, and these are also included in the elastic member 16. Furthermore, the thickness of the silicone rubber sheet, which is an example of the elastic membrane 15, is not limited to 0.5 mm, and may be other thicknesses.

[0067] The semipermeable membrane element 1D prepared as described above was attached to a solvent-driven module, which was then incorporated into a solution treatment system to carry out a desalination experiment, which will be described later in the sections "Solvent-driven module" and "Solution treatment system."

[0068] (Second embodiment: Solvent-driven module) Next, a solvent-driven module according to a second embodiment will be described. FIG. 5 is a schematic diagram illustrating the solvent-driven module. A perspective, partial cross-sectional view of the solvent-driven module 100 is shown in FIG. As shown in FIG. 5, the solvent-driven module 100 includes a driving solution chamber 110 that contains a driving solution and is provided in a sealable manner, a second semipermeable membrane 20 that is connected to the driving solution chamber 110 and contacts the target solution on one side and the driving solution on the other side, and a semipermeable membrane element 1 that is connected to the driving solution chamber 110. Here, the semipermeable membrane element 1 is any one of the semipermeable membrane elements 1A, 1B, 1C, and 1D described above. The semipermeable membrane elements 1A, 1B, 1C, and 1D are collectively referred to as the semipermeable membrane element 1. For convenience of explanation, FIG. 5 shows a case where any one of the semipermeable membrane elements 1A, 1B, and 1C is used as the semipermeable membrane element 1. One side of the first semipermeable membrane 10 of the semipermeable membrane element 1 contacts the driving solution contained in the driving solution chamber 110. A treated water chamber 111 is provided on the other side of the first semipermeable membrane 10 of the semipermeable membrane element 1 (the side opposite to the driving solution chamber 110).

[0069] Specifically, the second semipermeable membrane 20 is disposed and joined inside a flange 112a provided on the side of the driving solution chamber 110 for connection to a treatment tank to which the target solution is supplied. The flange 112a is provided with a screw hole 114 for connection to the treatment tank. In addition, the mesh membrane 21 is disposed and joined in the same manner to reinforce the second semipermeable membrane 20. In this embodiment, the second semipermeable membrane 20 and the mesh membrane 21 are joined by a pressure-bonding method using a screw 113a, but a pressure-bonding method using a spring or an adhesive may also be used. In this embodiment, in order to ensure the pressure-bonding, a support frame 22 is disposed on the second semipermeable membrane 20 and the mesh membrane 21, and the support frame 22 is fastened from above by a screw 113a. Furthermore, a sealant may be applied to the joint to prevent liquid leakage.

[0070] A semipermeable membrane that has been used in the conventional FO method, i.e., a semipermeable membrane having a thickness equal to or less than the permeation limit, can be used for the second semipermeable membrane 20. For example, a cellulose acetate-based semipermeable membrane can be used for the second semipermeable membrane 20, but is not limited thereto.

[0071] The driving solution chamber 110 is provided with a flange 112b for connecting the semipermeable membrane element 1 on the side opposite to the flange 112a to which the second semipermeable membrane 20 is joined. A pipe 115a for supplying a driving solution and a valve 116a are provided on the upper part. In a <Solution Processing System (No. 5)> of (Third Embodiment: Solution Processing System) described later, the driving solution chamber 110 is separated into two chambers, a driving solution chamber 110a (see FIG. 10) and a driving solution chamber 110b (see FIG. 10). In the driving solution chamber 110a, a flange 112b for connecting the semipermeable membrane element 1D-2 is provided on the side opposite to the flange 112a to which the second semipermeable membrane 20 is joined, and a pipe 115a for supplying a driving solution and a valve 116a are provided on the upper part. On the other hand, in the driving solution chamber 110b, a flange 112b for connecting the elastic member 16 is provided, and also a pipe 115a and a valve 116a for supplying the driving solution are provided.

[0072] The semipermeable membrane element 1 is joined between a flange 112b provided in the driving solution chamber 110 and a flange 112c provided in the treatment water chamber 111. In a semipermeable membrane element 1 having an integrally connected arrangement structure, the flanges 112b and 112c clamp the outer circumferential portion of the elastic membrane 15 of the semipermeable membrane element 1 to join the semipermeable membrane element 1. On the other hand, in a semipermeable membrane element 1 having a separated arrangement structure, the semipermeable membrane element 1 is joined by clamping the outer circumferential portions of the semipermeable membrane member 11 and the elastic member 16 of the semipermeable membrane element 1. In this embodiment, the joining method was a pressure-bonding method using the screw 113b, as with the second semipermeable membrane 20. The joining method may be a pressure-bonding method using a spring or an adhesive fixing method using an adhesive. The elastic membrane 15, semipermeable membrane member 11, and elastic member 16 of the semipermeable membrane element 1 have good adhesion to the flanges 112b and 112c and also function as sealing materials, so liquid leakage from the joints with the flanges 112b and 112c is unlikely to occur, but if necessary, additional sealing materials may be applied to prevent liquid leakage.

[0073] As shown in Figures 1B to 1G, there are four types of semipermeable membrane elements 1, namely, semipermeable membrane elements 1A, 1B, 1C, and 1D. Each semipermeable membrane element 1 can be easily replaced by opening and closing two flanges 112b and 112c. The treated water chamber 111 is provided on the other side of the semipermeable membrane element 1 (the side opposite to the driving solution chamber 110). Provided above the treated water chamber 111 are a pipe 115b and a valve 116b for supplying fresh water, and a pipe 115c for delivering treated water.

[0074] (Third embodiment: solution processing system) Next, a solution processing system according to a third embodiment will be described.

[0075] <Solution Processing System (Part 1)> FIG. 6 is a schematic diagram illustrating a solution processing system (part 1). 6 includes a solvent-driven module 100, a treatment tank 515, a pretreatment tank 516, a pump 517 for supplying a solution, and a treated water storage tank 518. The solvent-driven module 100 used in the solution treatment system 500A includes a second semipermeable membrane 20, a driving solution chamber 110 in contact with the second semipermeable membrane 20, a semipermeable membrane element 1A in contact with the driving solution chamber 110, and a treated water chamber 111 in contact with the semipermeable membrane element 1A.

[0076] A demonstration experiment of seawater desalination was carried out as a solution treatment using this solution treatment system 500A. The seawater desalination treatment is carried out according to the following steps.

[0077] (Step 1) First, the driving solution 510 (50 wt % sucrose water, osmotic pressure about 65 atm) and fresh water 511 are supplied to the driving solution chamber 110 and the treated water chamber 111 of the solvent-driven module 100 through the pipes 115a and 115b, respectively, to fill each chamber with liquid. At this time, the semipermeable membrane 10a (agar gel membrane about 5 mm thick) of the semipermeable membrane element 1A is in a state of permeation stop due to a membrane thickness above the permeation limit, so forward osmosis does not occur through the semipermeable membrane 10a. In other words, there is no movement of water from the fresh water side (treated water chamber 111 side) to the 50 wt % sucrose water side (driving solution chamber 110 side), and both liquid levels are kept constant.

[0078] (Step 2) Next, seawater L1 (raw water, concentration of about 3.5 wt%, osmotic pressure of about 25 atm) from which unnecessary substances such as garbage and impurities have been removed in pretreatment tank 516 is supplied to treatment tank 515 by pump 517. When seawater L1 is supplied to treatment tank 515, desalination treatment by solvent-driven module 100 begins. That is, the solvent (water) of the supplied seawater L1 moves (permeates) to the driving solution chamber 110 side through second semipermeable membrane 20 due to the osmotic pressure difference (about 40 atm) between seawater (low osmotic pressure side) and 50 wt% sucrose water (high osmotic pressure side) and is absorbed into the sucrose water, and the volume of the sucrose water gradually increases. Then, the water levels in driving solution chamber 110 and pipe 115a rise accordingly, so valve 116a is closed.

[0079] (Step 3) Closing the valve 116a seals the driving solution chamber 110, and the internal pressure of the driving solution chamber 110 gradually increases. This internal pressure increase gradually stretches the elastic membrane 15 (a silicone rubber sheet with a thickness of about 0.5 mm) of the semipermeable membrane element 1A, which then expands further due to the inflow of permeate water associated with the expansion, and the restoring force of the elastic membrane 15 increases. Then, due to this increasing restoring force, the permeate water is pushed out through the semipermeable membrane 10a to the treated water chamber 111, where it is absorbed into the fresh water 511, and the water level of the fresh water 511 rises. Meanwhile, on the driving solution chamber 110 side, the internal pressure drop caused by the permeate water being pushed out causes the elastic membrane 15 of the semipermeable membrane element 1A to contract, and the driving solution chamber 110 connected to it also contracts, causing the sucrose water concentration to increase and return to a concentration close to the state when the valve 116a was closed in step 2. In other words, the elastic membrane 15 functions as a diaphragm to adjust the internal pressure of the drive solution chamber 110, thereby cyclically performing a series of water movements from the treatment tank 515 to the drive solution chamber 110 via the second semipermeable membrane 20, and then from the drive solution chamber 110 to the treated water chamber 111 via the first semipermeable membrane 10.

[0080] (Step 4) Steps 2 and 3 are constantly repeated, and when the water level in the treated water chamber 111 reaches a certain level or higher, the treated water L2 (fresh water) flows out through the pipe 115c into the treated water storage tank 518 and is stored there.

[0081] In an experiment following the above steps, first, it was confirmed that in step 1, water did not move from the fresh water side to the 50 wt % sucrose water side through the semipermeable membrane 10a of the semipermeable membrane element 1A, and that the semipermeable membrane 10a (agar membrane with a thickness of about 5 mm) had a thickness equal to or greater than the permeability limit. It was also confirmed that the water level in the treated water storage tank 518 rose over time, and steps 2 and 3 were constantly repeated. Furthermore, it was confirmed that the internal pressure of the driving solution chamber 110 was estimated to be about several atmospheres based on the degree of expansion, and that this was at least significantly lower than the several tens of atmospheres required for the RO method.

[0082] The results of this experiment demonstrated that the pressure in the drive solution chamber 110 increases due to the solvent (water) drawn out from the target solution through the (permeable) semipermeable membrane by the FO method, and the solvent (water) is pushed out through the thick (non-permeable) semipermeable membrane 10a that is above its permeability limit, and that this eliminates the need for a drive solution separation process, i.e., eliminates the need for external energy.

[0083] In this embodiment, sucrose is used as the driving microparticle of the driving solution 510, but any microparticle that has high solubility and whose aqueous solution shows high osmotic pressure can be used as the driving microparticle. For example, sugars such as glucose, fructose, maltose, etc., alcohols such as ethanol (ethyl alcohol), glycerol (glycerin), ethylene glycol, etc., and salts such as sodium chloride (NaCl), magnesium chloride (MgCl2), calcium chloride (CaCl2), etc. are applicable. In this embodiment, the concentration of the sucrose water is set to 50 wt%, but this is only an example, and it may be higher or even saturated. This maximizes the internal pressure of the driving solution chamber 110 and increases the flow rate to the treatment water chamber 111.

[0084] <Solution Processing System (Part 2)> FIG. 7 is a schematic diagram illustrating a solution processing system (part 2). 7 includes a solvent-driven module 100, a treatment tank 515, a pretreatment tank 516, a pump 517 for supplying a solution, and a treated water storage tank 518. The solvent-driven module 100 used in the solution treatment system 500B includes a second semipermeable membrane 20, a driving solution chamber 110 in contact with the second semipermeable membrane 20, a semipermeable membrane element 1B in contact with the driving solution chamber 110, and a treated water chamber 111 in contact with the semipermeable membrane element 1B.

[0085] A demonstration experiment of seawater desalination was carried out as a solution treatment using this solution treatment system 500B. The seawater desalination treatment is carried out according to the following steps.

[0086] (Step 1) First, the driving solution 510 (50 wt % sucrose water, osmotic pressure about 65 atm) and fresh water 511 are supplied to the driving solution chamber 110 and the treated water chamber 111 of the solvent-driven module 100 through the pipes 115a and 115b, respectively, to fill each chamber with liquid. At this time, the first semipermeable membrane 10 having a two-layered semipermeable membrane 10b (lower layer) / semipermeable membrane 10a (upper layer) (cellophane membrane / agar gel membrane about 5 mm thick) of the semipermeable membrane element 1B is in a permeation-stopped state with a thickness equal to or greater than the permeation limit, so forward osmosis does not occur through the semipermeable membranes 10b / 10a. In other words, there is no movement of water from the fresh water side to the 50 wt % sucrose water side, and both liquid levels are kept constant.

[0087] (Step 2) Next, seawater L1 (raw water, concentration of about 3.5 wt%, osmotic pressure of about 25 atm) from which unnecessary substances such as garbage and impurities have been removed in pretreatment tank 516 is supplied to treatment tank 515 by pump 517. When seawater L1 is supplied to treatment tank 515, desalination treatment by solvent-driven module 100 begins. That is, the solvent (water) of the supplied seawater L1 moves (permeates) to the driving solution chamber 110 side through second semipermeable membrane 20 due to the osmotic pressure difference (about 40 atm) between seawater (low osmotic pressure side) and 50 wt% sucrose water (high osmotic pressure side) and is absorbed into the sucrose water, and the volume of the sucrose water gradually increases. Then, the water levels in driving solution chamber 110 and pipe 115a rise accordingly, so valve 116a is closed.

[0088] (Step 3) Closing the valve 116a seals the driving solution chamber 110, and the internal pressure of the driving solution chamber 110 gradually increases. This internal pressure increase gradually stretches the elastic membrane 15 (a silicone rubber sheet with a thickness of about 0.5 mm) of the semipermeable membrane element 1B, which further expands due to the inflow of permeate water accompanying the expansion, and the restoring force of the elastic membrane 15 increases. Then, due to this increasing restoring force, the permeate water is pushed out through the semipermeable membranes 10b / 10a to the treated water chamber 111 side and is absorbed by the fresh water 511, and the water level of the fresh water 511 rises. Meanwhile, on the driving solution chamber 110 side, the internal pressure drop caused by the permeate water being pushed out causes the elastic membrane 15 of the semipermeable membrane element 1B to contract, and the driving solution chamber 110 connected to it also contracts, causing the sucrose water concentration to increase and return to a concentration close to the state when the valve 116a was closed in step 2. In other words, the elastic membrane 15 functions as a diaphragm to adjust the internal pressure of the drive solution chamber 110, thereby cyclically performing a series of water movements from the treatment tank 515 to the drive solution chamber 110 via the second semipermeable membrane 20, and then from the drive solution chamber 110 to the treated water chamber 111 via the first semipermeable membrane 10.

[0089] (Step 4) Steps 2 and 3 are constantly repeated, and when the water level in the treated water chamber 111 reaches a certain level, the treated water L2 (fresh water) flows out through the pipe 115c into the treated water storage tank 518 and is stored there.

[0090] In an experiment following the above steps, first, in step 1, it was confirmed that water did not move from the fresh water side to the 50 wt % sucrose water side through the semipermeable membrane 10b / 10a of the semipermeable membrane element 1B, and that the semipermeable membrane 10b / 10a (cellophane membrane / agar gel membrane with a thickness of about 5 mm) had a thickness equal to or greater than the permeation limit. It was also confirmed that the water level in the treated water storage tank 518 increased over time, and steps 2 and 3 were constantly repeated. Furthermore, it was confirmed that the internal pressure of the driving solution chamber 110 was estimated to be about several atmospheres based on the degree of expansion, and that this was at least significantly lower than the several tens of atmospheres required for the RO method.

[0091] The results of this experiment demonstrated that the pressure in the drive solution chamber increases due to the solvent (water) drawn out from the target solution through the (permeable) semipermeable membrane by the FO method, and the solvent (water) is pushed out through the thick (non-permeable) semipermeable membrane 10b / 10a, which is above its permeability limit, and that this eliminates the need for a separation process for the drive solution, i.e., eliminates the need for external energy.

[0092] In this embodiment, sucrose is used as the driving microparticle of the driving solution 510, but any microparticle that has high solubility and whose aqueous solution shows high osmotic pressure can be used as the driving microparticle. For example, sugars such as glucose, fructose, maltose, etc., alcohols such as ethanol (ethyl alcohol), glycerol (glycerin), ethylene glycol, etc., and salts such as sodium chloride (NaCl), magnesium chloride (MgCl2), calcium chloride (CaCl2), etc. are applicable. In this embodiment, the concentration of the sucrose water is set to 50 wt%, but this is only an example, and it may be higher or even saturated. This maximizes the internal pressure of the driving solution chamber 110 and increases the flow rate to the treatment water chamber.

[0093] <Solution Processing System (Part 3)> FIG. 8 is a schematic diagram illustrating a solution processing system (part 3). 8 includes a solvent-driven module 100, a treatment tank 515, a pretreatment tank 516, a pump 517 for supplying a solution, and a treated water storage tank 518. The solvent-driven module 100 used in the solution treatment system 500C includes a second semipermeable membrane 20, a driving solution chamber 110 in contact with the second semipermeable membrane 20, a semipermeable membrane element 1C in contact with the driving solution chamber 110, and a treated water chamber 111 in contact with the semipermeable membrane element 1C.

[0094] A demonstration experiment of seawater desalination was carried out as a solution treatment using this solution treatment system 500C. The seawater desalination treatment is carried out according to the following steps.

[0095] (Step 1) First, the driving solution 510 (50 wt % sucrose water, osmotic pressure about 65 atm) and fresh water 511 are supplied to the driving solution chamber 110 and the treated water chamber 111 of the solvent-driven module 100 through the pipes 115a and 115b, respectively, to fill each chamber with liquid. At this time, the three-layered semipermeable membranes 10b (lower layer) / 10a (middle layer) / 10c (upper layer) (cellophane membrane / agar gel membrane / cellophane membrane, about 5 mm thick) of the semipermeable membrane element 1C are in a permeation-stopped state due to a membrane thickness above the permeation limit, so forward osmosis does not occur through the semipermeable membranes 10b / 10a / 10c. In other words, there is no movement of water from the fresh water side to the 50 wt % sucrose water side, and both liquid levels are kept constant.

[0096] (Step 2) Next, seawater L1 (raw water, concentration of about 3.5 wt%, osmotic pressure of about 25 atm) from which unnecessary substances such as garbage and impurities have been removed in pretreatment tank 516 is supplied to treatment tank 515 by pump 517. When seawater L1 is supplied to treatment tank 515, desalination treatment by solvent-driven module 100 begins. That is, the solvent (water) of the supplied seawater L1 moves (permeates) to the driving solution chamber 110 side through second semipermeable membrane 20 due to the osmotic pressure difference (about 40 atm) between seawater (low osmotic pressure side) and 50 wt% sucrose water (high osmotic pressure side) and is absorbed into the sucrose water, and the volume of the sucrose water gradually increases. Then, the water levels in driving solution chamber 110 and pipe 115a rise accordingly, so valve 116a is closed.

[0097] (Step 3) Closing the valve 116a seals the driving solution chamber 110, and the internal pressure of the driving solution chamber 110 gradually increases. This internal pressure increase gradually stretches the elastic membrane 15 (a silicone rubber sheet with a thickness of about 0.5 mm) of the semipermeable membrane element 1C, which further expands due to the inflow of osmotic water accompanying the expansion, and the restoring force of the elastic membrane 15 increases. Then, due to this increasing restoring force, the osmotic water is pushed out through the semipermeable membranes 10b / 10a / 10c to the treated water chamber 111 side and absorbed into the fresh water 511, causing the water level of the fresh water 511 to rise. Meanwhile, on the driving solution chamber 110 side, the internal pressure drop caused by the osmotic water being pushed out causes the elastic membrane 15 of the semipermeable membrane element 1C to contract, and the driving solution chamber 110 connected thereto also contracts, causing the sucrose water concentration to increase and return to a concentration close to the state when the valve 116a was closed in step 2. In other words, the elastic membrane 15 functions as a diaphragm to adjust the internal pressure of the drive solution chamber 110, thereby cyclically performing a series of water movements from the treatment tank 515 to the drive solution chamber 110 via the second semipermeable membrane 20, and then from the drive solution chamber 110 to the treated water chamber 111 via the first semipermeable membrane 10.

[0098] (Step 4) Steps 2 and 3 are constantly repeated, and when the water level in the treated water chamber 111 reaches a certain level, the treated water L2 (fresh water) flows out through the pipe 115c into the treated water storage tank 518 and is stored there.

[0099] In an experiment following the above steps, first, in step 1, it was confirmed that water did not move from the fresh water side to the 50 wt% sucrose water side through the semipermeable membranes 10b / 10a / 10c of the semipermeable membrane element 1C, and that the semipermeable membranes 10b / 10a / 10c (cellophane membrane / agar gel membrane / cellophane membrane with a thickness of about 5 mm) had a thickness equal to or greater than the permeation limit. It was also confirmed that the water level in the treated water storage tank 518 increased over time, and steps 2 and 3 were constantly repeated. Furthermore, it was confirmed that the internal pressure of the driving solution chamber 110 was estimated to be about several atmospheres based on the degree of expansion, and that this was at least significantly lower than the several tens of atmospheres required for the RO method.

[0100] The results of this experiment demonstrated that the pressure in the drive solution chamber increases due to the solvent (water) drawn out from the target solution through the (permeable) semipermeable membrane by the FO method, and the solvent (water) is pushed out through the thick (non-permeable) semipermeable membranes 10b / 10a / 10c that are above their permeability limit, and that this eliminates the need for a separation process for the drive solution, i.e., eliminates the need for external energy.

[0101] In this embodiment, sucrose is used as the driving microparticle of the driving solution 510, but any microparticle that has high solubility and whose aqueous solution shows high osmotic pressure can be used as the driving microparticle. For example, sugars such as glucose, fructose, maltose, etc., alcohols such as ethanol (ethyl alcohol), glycerol (glycerin), ethylene glycol, etc., and salts such as sodium chloride (NaCl), magnesium chloride (MgCl2), calcium chloride (CaCl2), etc. are applicable. In addition, the concentration of the sucrose water is set to 50 wt%, but this is only one example, and it may be higher or even saturated. This maximizes the internal pressure of the driving solution chamber 110 and increases the flow rate to the treatment water chamber.

[0102] <Solution Processing System (Part 4)> FIG. 9 is a schematic diagram illustrating a solution processing system (part 4). 9 includes a solvent-driven module 100, a treatment tank 515, a pretreatment tank 516, a pump 517 for supplying a solution, and a treated water storage tank 518. The solvent-driven module 100 used in the solution treatment system 500D includes a second semipermeable membrane 20, a driving solution chamber 110 in contact with the second semipermeable membrane 20, a semipermeable membrane element 1D-1 in contact with the driving solution chamber 110, and a treated water chamber 111 in contact with the semipermeable membrane element 1D-1.

[0103] A demonstration experiment of seawater desalination was carried out as a solution treatment using this solution treatment system 500D. The seawater desalination process is carried out according to the following steps.

[0104] (Step 1) First, the driving solution 510 (50 wt % sucrose water, osmotic pressure about 65 atm) and fresh water 511 are supplied to the driving solution chamber 110 and the treated water chamber 111 of the solvent-driven module 100 through the pipes 115a and 115b, respectively, to fill each chamber with liquid. At this time, the semipermeable membrane 10a (cellophane membrane about 1 mm thick) of the semipermeable membrane element 1D-1 is in a state of permeation stop due to a membrane thickness above the permeation limit, so forward osmosis does not occur through the semipermeable membrane 10a. In other words, there is no movement of water from the fresh water side (treated water chamber 111 side) to the 50 wt % sucrose water side (driving solution chamber 110 side), and both liquid levels are kept constant.

[0105] (Step 2) Next, seawater L1 (raw water, concentration of about 3.5 wt%, osmotic pressure of about 25 atm) from which unnecessary substances such as garbage and impurities have been removed in pretreatment tank 516 is supplied to treatment tank 515 by pump 517. When seawater L1 is supplied to treatment tank 515, desalination treatment by solvent-driven module 100 begins. That is, the solvent (water) of the supplied seawater L1 moves (permeates) to the driving solution chamber 110 side through second semipermeable membrane 20 due to the osmotic pressure difference (about 40 atm) between seawater (low osmotic pressure side) and 50 wt% sucrose water (high osmotic pressure side) and is absorbed into the sucrose water, and the volume of the sucrose water gradually increases. Then, the water levels in driving solution chamber 110 and pipe 115a rise accordingly, so valve 116a is closed.

[0106] (Step 3) Closing the valve 116a seals the driving solution chamber 110, and the internal pressure of the driving solution chamber 110 gradually increases. This internal pressure increase gradually stretches the elastic membrane 15 (a silicone rubber sheet with a thickness of about 0.5 mm) of the semipermeable membrane element 1D-1, which further expands due to the inflow of permeate water accompanying the expansion, and the restoring force of the elastic membrane 15 increases. Then, due to this increasing restoring force, the permeate water is pushed out through the semipermeable membrane 10a to the treated water chamber 111 side and absorbed into the fresh water 511, causing the water level of the fresh water 511 to rise. Meanwhile, on the driving solution chamber 110 side, the internal pressure drop caused by the permeate water being pushed out causes the elastic membrane 15 of the semipermeable membrane element 1D-1 to contract, and the driving solution chamber 110 connected to it also contracts, causing the sucrose water concentration to increase and return to a concentration close to the state when the valve 116a was closed in step 2. In other words, the elastic membrane 15 functions as a diaphragm to adjust the internal pressure of the drive solution chamber 110, thereby cyclically performing a series of water movements from the treatment tank 515 to the drive solution chamber 110 via the second semipermeable membrane 20, and then from the drive solution chamber 110 to the treated water chamber 111 via the first semipermeable membrane 10.

[0107] (Step 4) Steps 2 and 3 are constantly repeated, and when the water level in the treated water chamber 111 reaches a certain level or higher, the treated water L2 (fresh water) flows out through the pipe 115c into the treated water storage tank 518 and is stored there.

[0108] In an experiment following the above steps, first, it was confirmed that in step 1, water did not move from the fresh water side to the 50 wt % sucrose water side through the semipermeable membrane 10a of the semipermeable membrane element 1D-1, and that the semipermeable membrane 10a (cellophane membrane with a thickness of about 1 mm) had a thickness equal to or greater than the permeability limit. It was also confirmed that the water level in the treated water storage tank 518 rose over time, and steps 2 and 3 were constantly repeated. Furthermore, it was confirmed that the internal pressure of the driving solution chamber 110 was estimated to be about several atmospheres based on the degree of expansion, and that this was at least considerably lower than the several tens of atmospheres required for the RO method.

[0109] The results of this experiment demonstrated that the pressure in the drive solution chamber 110 increases due to the solvent (water) drawn out from the target solution through the (permeable) semipermeable membrane by the FO method, and the solvent (water) is pushed out through the thick (non-permeable) semipermeable membrane 10a that is above its permeability limit, and that this eliminates the need for a drive solution separation process, i.e., eliminates the need for external energy.

[0110] In this embodiment, sucrose is used as the driving microparticle of the driving solution 510, but any microparticle that has high solubility and whose aqueous solution shows high osmotic pressure can be used as the driving microparticle. For example, sugars such as glucose, fructose, maltose, etc., alcohols such as ethanol (ethyl alcohol), glycerol (glycerin), ethylene glycol, etc., and salts such as sodium chloride (NaCl), magnesium chloride (MgCl2), calcium chloride (CaCl2), etc. are applicable. In this embodiment, the concentration of the sucrose water is set to 50 wt%, but this is only an example, and it may be higher or even saturated. This maximizes the internal pressure of the driving solution chamber 110 and increases the flow rate to the treatment water chamber 111.

[0111] <Solution Processing System (Part 5)> FIG. 10 is a schematic diagram illustrating a solution processing system (part 5). 10 includes a solvent driving module 100, a treatment tank 515, a pretreatment tank 516, a solution supply pump 517, and a treated water storage tank 518. The solvent driving module 100 used in the solution processing system 500E includes a second semipermeable membrane 20, a driving solution chamber 110 in contact with the second semipermeable membrane 20, a semipermeable membrane element 1D-2 in contact with the driving solution chamber 110, and a treated water chamber 111 in contact with the semipermeable membrane element 1D-2. In the solution processing system 500E of this embodiment, the driving solution chamber 110 is separated into two chambers, a driving solution chamber 110a and a driving solution chamber 110b, which are connected by a pipe, and each chamber includes a semipermeable membrane member 11 and an elastic member 16 of the semipermeable membrane element 1D-2 arranged separately. As a result, the driving solution chamber 110a and the driving solution chamber 110b are separate (separate) regions, but are mutually at the same pressure. Since the driving solution chamber 110a and the driving solution chamber 110b are arranged separately, it becomes easy to open the driving solution chamber 110b and replace only the elastic member 16 without opening the driving solution chamber 110a. Also, it becomes easy to open the driving solution chamber 110a and replace only the first semipermeable membrane 10 without opening the driving solution chamber 110b.

[0112] A demonstration experiment of seawater desalination was carried out as a solution treatment using this solution treatment system 500E. The seawater desalination treatment is carried out according to the following steps.

[0113] (Step 1) First, the driving solution 510 (50 wt % sucrose water, osmotic pressure of about 65 atm) and fresh water 511 are supplied through the pipes 115a and 115b to the driving solution chamber 110a, driving solution chamber 110b, and treated water chamber 111 of the solvent-driven module 100, respectively, to fill each chamber with liquid. At this time, the semipermeable membrane 10a (cellophane membrane with a thickness of about 1 mm) of the semipermeable membrane element 1D-2 is in a state of permeation stop due to a membrane thickness equal to or greater than the permeation limit, so forward osmosis does not occur through the semipermeable membrane 10a. In other words, there is no movement of water from the fresh water side (treated water chamber 111 side) to the 50 wt % sucrose water side (driving solution chamber 110 side), and both liquid levels are kept constant.

[0114] (Step 2) Next, seawater L1 (raw water, concentration of about 3.5 wt%, osmotic pressure of about 25 atm) from which unnecessary substances such as garbage and impurities have been removed in pretreatment tank 516 is supplied to treatment tank 515 by pump 517. When seawater L1 is supplied to treatment tank 515, desalination treatment by solvent-driven module 100 begins. That is, the solvent (water) of the supplied seawater L1 moves (permeates) to the driving solution chamber 110 side through second semipermeable membrane 20 due to the osmotic pressure difference (about 40 atm) between seawater (low osmotic pressure side) and 50 wt% sucrose water (high osmotic pressure side) and is absorbed into the sucrose water, and the volume of the sucrose water gradually increases. Then, the water levels in driving solution chamber 110a and pipe 115a rise accordingly, so valve 116a is closed.

[0115] (Step 3) Closing the valve 116a seals the driving solution chamber 110a and the driving solution chamber 110b, and the internal pressure of the driving solution chamber 110 gradually increases. This internal pressure increase gradually stretches the elastic membrane 15 (a silicone rubber sheet with a thickness of about 0.5 mm) of the semipermeable membrane element 1D-2, which further expands due to the inflow of osmotic water accompanying the expansion, and the restoring force of the elastic membrane 15 increases. Then, due to this increasing restoring force, the osmotic water is pushed through the semipermeable membrane 10a to the treated water chamber 111 side and absorbed by the fresh water 511, and the water level of the fresh water 511 rises. Meanwhile, on the driving solution chamber 110 side, the internal pressure drop caused by the osmotic water being pushed out causes the elastic membrane 15 of the semipermeable membrane element 1D-2 to contract, and the driving solution chamber 110b connected to it also contracts, causing the sucrose water concentration to increase and return to a concentration close to the state when the valve 116a was closed in step 2. In other words, the elastic membrane 15 functions as a diaphragm to adjust the internal pressure of the driving solution chamber 110a and the driving solution chamber 110b, thereby cyclically performing a series of water movements from the treatment tank 515 to the driving solution chamber 110a via the second semipermeable membrane 20, and further from the driving solution chamber 110a to the treated water chamber 111 via the first semipermeable membrane 10.

[0116] (Step 4) Steps 2 and 3 are constantly repeated, and when the water level in the treated water chamber 111 reaches a certain level or higher, the treated water L2 (fresh water) flows out through the pipe 115c into the treated water storage tank 518 and is stored there.

[0117] In an experiment following the above steps, first, in step 1, it was confirmed that water did not move from the fresh water side to the 50 wt % sucrose water side through the semipermeable membrane 10a of the semipermeable membrane element 1D-2, and that the semipermeable membrane 10a (cellophane membrane with a thickness of about 1 mm) had a thickness equal to or greater than the permeability limit. It was also confirmed that the water level in the treated water storage tank 518 rose over time, and steps 2 and 3 were constantly repeated. Furthermore, it was confirmed that the internal pressure of the driving solution chamber 110 was estimated to be about several atmospheres based on the degree of expansion, and that this was at least considerably lower than the several tens of atmospheres required for the RO method. Furthermore, as described above, by separating the driving solution chamber into two, it becomes possible to separate the semipermeable membrane member and the elastic member and join them to the driving solution chamber, thereby improving convenience for refilling chemical solutions, maintenance, etc., and further enhancing practicality.

[0118] The results of this experiment demonstrated that the pressure in the drive solution chamber 110 increases due to the solvent (water) drawn out from the target solution through the (permeable) semipermeable membrane by the FO method, and the solvent (water) is pushed out through the thick (non-permeable) semipermeable membrane 10a that is above its permeability limit, and that this eliminates the need for a drive solution separation process, i.e., eliminates the need for external energy.

[0119] In this embodiment, sucrose is used as the driving microparticle of the driving solution 510, but any microparticle that has high solubility and whose aqueous solution shows high osmotic pressure can be used as the driving microparticle. For example, sugars such as glucose, fructose, maltose, etc., alcohols such as ethanol (ethyl alcohol), glycerol (glycerin), ethylene glycol, etc., and salts such as sodium chloride (NaCl), magnesium chloride (MgCl2), calcium chloride (CaCl2), etc. are applicable. In this embodiment, the concentration of the sucrose water is set to 50 wt%, but this is only an example, and it may be higher or even saturated. This maximizes the internal pressure of the driving solution chamber 110 and increases the flow rate to the treatment water chamber 111.

[0120] As described above, the semipermeable membrane elements 1A, 1B, 1C, and 1D and the solvent-driven module 100 according to the embodiments make it possible to easily separate the solvent extracted from the target solution from the driving solution in solution treatment by the FO method.

[0121] Although the present embodiment and its application examples (variations, specific examples) have been described above, the present invention is not limited to these examples. For example, in the above example, seawater desalination is used as an example of solution processing, and water is used as an example of a solvent, but the present invention can also be applied to processing of solutions other than seawater (processing of extracting a solvent from a solution). In this case, the solvent is other than water. Furthermore, those in which a person skilled in the art appropriately adds, deletes, or modifies components of the above-mentioned embodiments or their application examples (variations, specific examples), or those in which the features of each embodiment are appropriately combined, are also included within the scope of the present invention as long as they include the gist of the present invention. [Explanation of symbols]

[0122] 1, 1A, 1B, 1C, 1D, 1D-1, 1D-2...Semipermeable membrane element 10...First semipermeable membrane 10a,10b,10c...Semi-permeable membrane 11...Semipermeable membrane member 12...Opening 13…Frame section 14…Joint part 15...Elastic membrane 16...Elastic membrane member 17…Opening 18…Frame section 19…Joint part 20…Second semipermeable membrane 21...Membrane 22…Support frame 31,32...Semi-permeable membrane 100…Solvent-driven module 110, 110a, 110b... Driving solution chamber 111…Water treatment room 112a, 112b, 112c...Flanges 113a, 113b…Screws 114…Screw hole 115a, 115b, 115c...Pipes 116a, 116b... Valve 500A, 500B, 500C, 500D, 500E...Solution processing systems 510...Drive solution 511...Fresh water 515...Treatment tank 516…Pretreatment tank 517…Pump 518…Treated water storage tank 800a, 800b...Solvent-driven module 810...Drive solution 815...Treatment tank 816...Pretreatment tank 817a, 817b…Pump 818…Treated water storage tank 819…Drive solution separation / adjustment tank 820…Semi-permeable membrane 830...Drive solution tank 840…Separation membrane L1…Seawater L2: Treated water La…fresh water Lb…Sucrose water

Claims

1. A semipermeable membrane element for forcing a solvent contained in a target solution through a semipermeable membrane by pressure, A semipermeable membrane member having a first semipermeable membrane at least in a portion thereof; An elastic member that is integrally connected to or separately arranged with respect to the semipermeable membrane member and has an elastic membrane at least in a portion thereof; A semipermeable membrane element comprising:

2. 2. The semipermeable membrane element according to claim 1, wherein the first semipermeable membrane has one or more types of layer structure and has a thickness equal to or greater than the permeation limit at which forward osmosis due to an osmotic pressure difference does not occur.

3. 2. The semipermeable membrane element according to claim 1, wherein the elastic membrane is made of a material having rubber elasticity.

4. A solvent-driven module having a function of drawing out a solvent contained in a target solution through a semipermeable membrane by an osmotic pressure difference, a driving solution chamber that contains a driving solution and is sealably provided; a second semipermeable membrane connected to the driving solution chamber, the second semipermeable membrane being in contact with the target solution on one side and the driving solution on the other side; A semipermeable membrane element according to any one of claims 1 to 3, which is connected to the driving solution chamber; Equipped with A solvent-driven module, wherein the first semipermeable membrane of the semipermeable membrane element faces the second semipermeable membrane and is in contact with the driving solution on the side facing the second semipermeable membrane.

5. 5. The solvent driving module according to claim 4, further comprising flanges provided between the second semipermeable membrane and the driving solution chamber, and between the driving solution chamber and the semipermeable membrane element, for detachably connecting the respective components.

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