JP2015037771A - Water treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment method in which fresh water can easily be produced from seawater or the like with low energy and at a low cost.SOLUTION: The water treatment method comprises: a forward osmosis step of bringing the water to be treated into contact with an induction solution, which is prepared by dissolving a temperature-sensitive substance in water, which substance has phase transition temperature, is hydrophilized when heated to the temperature equal to or higher than the phase transition temperature and is hydrophobized when cooled to the temperature equal to or lower than the phase transition temperature, while interposing a semipermeable membrane therebetween to move the water in the water to be treated to the induction solution through the semipermeable membrane and obtain the dilute induction solution diluted with the water and membrane-concentrated water; a cooling step of cooling the dilute induction solution to the temperature equal to or lower than the phase transition temperature; a solid-liquid separation step of subjecting the cooled dilute induction solution, which is cooled at the cooling step and contains the hydrophobized temperature-sensitive substance, to solid-liquid separation to obtain fresh water and a temperature-sensitive substance-concentrated solution; and a warming step of warming the temperature-sensitive substance-concentrated solution, which is separated at the solid-liquid separation step, to the temperature equal to or higher than the phase transition temperature to regenerate the induction solution. A water treatment device is also provided.

Description

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

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

  In the method of Patent Document 1, the water to be treated is brought into contact with one surface of the first semipermeable membrane, and the other surface of the first semipermeable membrane is kept at a relatively high temperature in an intermediate solution whose solubility depends on temperature. A moisture absorption step for allowing the intermediary solution to absorb the moisture of the water to be treated through the first semipermeable membrane, and the intermediary solution after the moisture absorption step to be at a relatively low temperature, And a moisture releasing step of bringing the mediator solution after the depositing step into contact with the second semipermeable membrane at a fluid pressure that allows the moisture of the mediator solution to be released through the second semipermeable membrane. Fresh water production method.

  In the method of Patent Document 2, a salt solution obtained by dissolving ammonia and carbon dioxide is passed through a semipermeable membrane on the side opposite to seawater, and water in the seawater is passed through the semipermeable membrane into the salt solution. The obtained diluted salt solution is separated into ammonium ions and carbonate ions individually using an ion exchange membrane or a distillation tower to obtain fresh water, and the separated ammonium ions and carbonate ions are dissolved in the salt solution. This is the method of returning to the original room of the semipermeable membrane.

This method is illustrated in FIG. 4, and a salt solution obtained by dissolving ammonia and carbon dioxide is flowed through the FO (Forward Osmosis) membrane, which is a semipermeable membrane, to the opposite side of the seawater. The water in seawater is moved to the salt solution through the FO membrane due to the difference between the two, and the diluted salt solution diluted with the water is sent to the distillation tower and heated to 60 ° C. to evaporate ammonia and carbon dioxide. The separated ammonia and carbon dioxide are separated and the separated ammonia and carbon dioxide are cooled to 30 ° C., regenerated into a salt solution, and returned to the FO membrane module. The regeneration energy required by this method is 360 MJ / m ³ , and the water supply cost is 1,300 yen / m ³ .

JP 2010-162527 A JP 2011-83663 A

  In the method of Patent Document 1, an aqueous solution of alum is used as a mediator, that is, a hyperosmotic solution. In the process, there is a problem that the liquid temperature adjustment range is large and the equipment operation cost is high, such as cooling to 30 ° C. Further, for example, in the case of potash alum, there is a problem that the pH is close to 3 and the apparatus is easily corroded.

In the method of Patent Document 2, the induction substance (for example, ammonium carbonate) is separated and recovered by an evaporation method. At that time, the latent heat of vaporization of ammonia and accompanying water is enormous, requiring enormous energy and cost. high. Furthermore, the size of the evaporation facility is extremely large, and is not suitable for producing a large amount (for example, 100,000 m ³ / day) of drinking water. Moreover, since the input energy is large, the size of the heat exchanger is also large, which is not suitable for mass processing. Further, when ammonium carbonate is used, an inducer that leaks into the environment through the membrane concentrated water due to backflow from the FO membrane contains nitrogen, which causes eutrophication.

  The present invention has been made to solve these problems, and an object of the present invention is to provide a water treatment method that can easily produce fresh water from seawater or the like with less energy and at low cost.

  The present invention has been made in order to solve the above-mentioned problems, and has a phase transition temperature, and becomes hydrophilic when heated to a temperature higher than this phase transition temperature and becomes hydrophobic when cooled to a temperature lower than the phase transition temperature. A forward osmosis membrane treatment is carried out using a high osmotic pressure induction solution prepared by dissolving the substance in water, and the resulting dilution induction solution is cooled below the phase transition temperature to make the thermosensitive substance hydrophobic. It was discovered that by separating and separating this, fresh water can be obtained easily and inexpensively from seawater and the like, and the present invention has been completed.

  That is, the present invention dissolves in water water to be treated and a temperature-sensitive substance that has a phase transition temperature, becomes hydrophilic when heated above the phase transition temperature, and becomes hydrophobic when cooled below the phase transition temperature. Forward osmosis step of contacting the induced solution through a semipermeable membrane, transferring the water in the treated water to the induced solution through the semipermeable membrane, and obtaining a diluted induced solution and membrane concentrated water diluted with water; A cooling step for cooling the dilution-inducing solution below the phase transition temperature; and a temperature-sensitive material that has been cooled and hydrophobized in the cooling step is separated from the dilution-inducing solution by solid-liquid separation to concentrate fresh water and the temperature-sensitive material. A solid-liquid separation step for obtaining a liquid; and a heating step for regenerating the induction solution by heating the temperature-sensitive substance concentrated liquid separated in the solid-liquid separation step above the phase transition temperature. A water treatment method is provided.

The method of the present invention includes the following aspects.
(1) The water treatment method as described above, wherein the solid-liquid separation means in the solid-liquid separation step is any one of a filtration membrane capable of separating particles having a particle size of 100 nm or more, centrifugal separation, and specific gravity separation. .
(2) The water treatment method as described above, wherein the phase transition temperature of the thermosensitive substance is in the range of 30 ° C to 80 ° C.
(3) The water treatment method described above, wherein the temperature-sensitive substance concentrate separated in the solid-liquid separation step is used as a cold heat source in the cooling step.
(4) The water treatment method described above, wherein the dilution induction solution obtained in the forward osmosis step is used as a heat source in the heating step.
(5) The water treatment method as described above, wherein the thermosensitive substance is a mixture of alcohol and fatty acid glycerin ester.

  The present invention also provides water to be treated and a temperature-sensitive substance that has a phase transition temperature, becomes hydrophilic when heated to the phase transition temperature or higher, and becomes hydrophobic when cooled to the phase transition temperature or lower. A forward osmosis membrane in which a dissolved induction solution is contacted through a semipermeable membrane, and water in the water to be treated is transferred to the induction solution through the semipermeable membrane to obtain a diluted induction solution and membrane concentrated water diluted with water. A treatment device, a cooling means for cooling the dilution-inducing solution below the phase transition temperature, and a thermosensitive substance that has been cooled and hydrophobized by the cooling means is separated from the dilution-inducing solution by solid-liquid separation, and fresh water and temperature sensitive A solid-liquid separation device for obtaining a concentrated concentrate, and a heating means for regenerating the induction solution by heating the temperature-sensitive substance concentrate separated by the solid-liquid separation device to a temperature higher than the phase transition temperature. The water treatment apparatus characterized by this is provided.

The apparatus of the present invention includes the following aspects.
(1) The water treatment apparatus described above, wherein the solid-liquid separation apparatus is an apparatus based on any one of a filtration membrane, centrifugal separation, and specific gravity separation capable of separating particles having a particle size of 100 nm or more.
(2) The water treatment apparatus as described above, wherein the thermosensitive substance is a mixture of alcohol and fatty acid glycerin ester.
(3) The water treatment apparatus as described above, wherein the phase transition temperature of the thermosensitive substance is in the range of 30 ° C to 80 ° C.

  For example, a mixture (draw) of alcohol and fatty acid glycerin ester, which is a temperature-sensitive substance of the present invention, dissolves at a high temperature and precipitates and becomes cloudy when cooled. In this cloudy state, the molecules gather together and the apparent number of molecules is greatly reduced, so the osmotic pressure is dramatically reduced. When the UF membrane is filtered in the aggregated state, the draw is removed by the membrane, and pure water is obtained as the filtrate. The concentrate is an agglomerated draw. When this is heated, it is re-dissolved and a regenerated draw is obtained. In the redrawn regenerated draw, since the draw is dispersed, a predetermined high osmotic pressure can be obtained. Pure water is obtained from the feed solution by introducing the regenerative draw into the semipermeable membrane device and contacting the feed solution through the membrane. Unlike the evaporation method, this method does not require the use of latent heat for phase change, so the input heat amount is extremely small. In addition, since the solid-liquid separation membrane aggregates and the draw becomes coarse, it can be filtered at a high permeation flow rate even if a membrane having a coarser mesh is used than RO / NF such as UF and MF. Since the osmotic pressure at this time is low, the filtration power is extremely small.

  In the present invention, by using the induction solution in which the thermosensitive substance is dissolved, the temperature adjustment range during the separation of the fresh water and the regeneration of the induction solution in the forward osmosis membrane treatment is reduced. Fresh water can be obtained efficiently.

It is the figure which showed one embodiment of this invention typically. It is a graph which shows the relationship between the mixture density | concentration of t-butanol and fatty-acid glycerol ester, and a phase transition temperature. It is a graph which shows the relationship between the liquid temperature of an induction | guidance | derivation solution, and light transmittance. It is the figure which showed typically the method of desalting by the conventional forward osmosis method.

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

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

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

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

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

The forward osmosis process The forward osmosis process has the water to be treated and the phase transition temperature. It becomes hydrophilic when heated above this phase transition temperature and becomes hydrophobic when cooled below the phase transition temperature. A high osmotic pressure induction solution in which a substance is dissolved in water is contacted through a semipermeable membrane, and water in the water to be treated is transferred to the induction solution through the semipermeable membrane, and a diluted induction solution diluted with water and This is a step of obtaining membrane concentrated water.

  A temperature-sensitive substance is a substance that becomes hydrophilic and dissolves well in water when heated, but becomes hydrophobic and decreases in solubility when cooled, and the temperature at which it changes from water-soluble to water-insoluble is called the phase transition temperature. When this temperature is reached, the temperature-sensitive material that has become hydrophobic is deposited, resulting in white turbidity.

  An example of this temperature sensitive substance is a mixture of fatty acid glycerin ester and alcohol.

  The fatty acid glycerin ester alone is a hydrophobic one having a cloud point of room temperature (10 ° C.) or less, and a fatty acid having about 8 to 18 carbon atoms is preferable because it has the same natural composition. Examples include caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and the like. The fatty acid glycerin ester may be any of mono-, di-, and tri-esters of these fatty acids. Specific examples include monoglycerin caprylic acid ester, diglycerin lauric acid ester having a long fatty acid chain length, monoglycerin stearic acid ester, and diglycerin oleic acid ester. The number of glycerin is not particularly limited as long as the hydrophobicity of the fatty acid glycerin ester is maintained, but many substances up to decaglycerin are industrially produced.

  Alcohol undergoes a phase transition reaction during cooling when polyethylene glycol is used. The molecular weight of polyethylene glycol may be in the range of 200 to 10,000, but if the molecular weight is too large, the viscosity increases and the fluidity decreases, so that the molecular weight is 6000 or less, more preferably for operating the apparatus with low pressure loss. Is suitably 3000 or less.

  The mixing ratio of the fatty acid glycerin ester and the alcohol is determined so that the HLB weighted average value of this mixture is about 12 to 15, and this means that the HLB value of the fatty acid glycerin ester to be used is 20 for the alcohol having a known HLB value. Can be obtained by calculation.

  Another example of the temperature-sensitive substance is a mixture of a sorbitan fatty acid ester ethylene oxide adduct and a sorbitan fatty acid ester. The ethylene oxide addition mole number of the sorbitan fatty acid ester ethylene oxide adduct may be 5 to 200, and if it is excessive, the viscosity becomes high, and is 100 or less, more preferably 5 to 30. Fatty acids having about 8 to 18 carbon atoms are preferred because they have the same natural composition. Examples include caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and the like.

  The fatty acid in the sorbitan fatty acid ester is the same as that of the sorbitan fatty acid ester ethylene oxide adduct.

The mixing ratio of the sorbitan fatty acid ester ethylene oxide adduct and the sorbitan fatty acid ester is determined so that the HLB weighted average value of this mixture is about 12 to 15,
The temperature-sensitive substance preferably has a phase transition temperature in the range of 30 ° C to 80 ° C, preferably 35 ° C to 45 ° C.

  The temperature-sensitive substance concentration is determined so that the osmotic pressure is higher than that of the water to be treated. However, the concentration should be as high as possible so that a high osmotic pressure can be obtained, and about 1 to 100%, particularly 10 to 95%. The degree is preferred.

  In the present invention, the phase transition temperature varies depending on the type and concentration of the temperature-sensitive substance, but is preferably adjusted to 30 to 80 ° C., preferably 35 to 45 ° C. in the next cooling step. If it is this temperature range, it can be easily cooled with ambient water at room temperature, and warm wastewater such as cooling wastewater can be used for heating when re-dissolving.

  The result of measuring the change in phase transition temperature by adding a mixture (temperature-sensitive substance) of polyethylene glycol (molecular weight 400) and monoglycerin caprylate ester in a weight ratio of 50:50 to water and changing the concentration of the mixture. As shown in FIG. As shown in the figure, the phase transition occurs when the concentration of the temperature-sensitive substance is in the range of 20 to 50% by weight, and the phase transition temperature changes linearly from 100 ° C. to 0 ° C. during that time.

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

  This semipermeable membrane mounting device is usually a bag-shaped semipermeable membrane installed in a cylindrical container (spiral type), and the membrane is placed in one chamber partitioned by this semipermeable membrane. The filtered water is allowed to flow, and the induction solution can be allowed to flow into the other chamber. A known semipermeable membrane device can be used, and a commercially available product can be used. Another shape is a straw-shaped membrane installed in a cylindrical container (hollow fiber type). Similarly, a known semipermeable membrane device can be used, and a commercially available product can be used.

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

Cooling step The dilution-inducing solution diluted by moving water from the water to be treated in the forward osmosis step is cooled to the phase transition temperature or lower, and at least a part of the temperature-sensitive substance is hydrophobized and precipitated. This deposit is a phase separation of a concentrated solution of a temperature sensitive substance. The cooling temperature is not higher than the phase transition temperature, but is preferably lower than the phase transition temperature, preferably 1 ° C. to 20 ° C., more preferably 2 ° C. to 5 ° C. lower than the phase transition temperature. By cooling, a mixture of alcohol and fatty acid glycerin ester precipitates and aggregates. The particle size of the aggregate is about 2,000 to 20,000 nm.

  It is preferable to use a liquid to be treated at room temperature for the cooling heat source in this cooling step.

Solid-Liquid Separation Step The diluted temperature-sensitive material is separated by solid-liquid separation of the diluted induction solution that has been cooled in the cooling step and the temperature-sensitive material is precipitated. This solid-liquid separation means should use reverse osmosis filtration membranes, ultrafiltration membranes, microfiltration membranes, sand filtration, filter cloth filtration, centrifugal separation, sedimentation separation, etc. that can separate particle sizes of 2,000 nm or more Can do. Preferred are ultrafiltration membranes, microfiltration membranes, and centrifugal separations because relatively low power and good separation efficiency can be obtained. In the case of high separation including unaggregated matter, a reverse osmosis filtration membrane is preferable because the highest separation efficiency can be obtained.

  The water separated by the solid-liquid separation means can usually be used as fresh water as it is, but it is further purified and used if necessary.

On the other hand, the concentrated solution of the temperature-sensitive substance separated is heated to the phase transition temperature or higher, specifically, to a temperature at which the white turbidity disappears, and regenerated into an induction solution. As the heat source, it is preferable to use the dilution induction solution obtained in the forward osmosis step from the viewpoint of efficient use of energy. In addition, low-temperature steam after power generation, warm waste water after cooling, and the like can be applied to unused low-temperature exhaust heat of 50 to 100 ° C., which is preferable in terms of efficient use of energy.

  The regenerated induction solution can be recycled as it is.

  On the other hand, since the membrane concentrated water obtained in the forward osmosis step contains a high concentration of salt, it can be concentrated and precipitated to separate and be effectively used.

This method of the present invention is shown schematically in FIG. The treatment may be a batch method, but in principle, the treatment is continuous, that is, the water to be treated and the induction solution are continuously flowed, and fresh water is continuously taken out. The amount of heat used in this method is 60 MJ / m ³ , and the water production cost is 1,000 yen / m ³ .

Example 1
A cellulose acetate FO membrane module is used as the forward osmosis membrane, and a mixture of monoglycerin caprylate and polyethylene glycol (molecular weight 400) in a weight ratio of 50:50 is dissolved in water at a concentration of 400 g / L in the induction solution. What was done was used. The osmotic pressure of the induction solution can be measured based on whether or not fresh water can be sucked from a predetermined concentration of salt water with an FO membrane, and was about 3.0 MPa in this solution. The phase transition temperature can be specified by measuring the absorbance and the transmittance becomes 10% or less, and the phase transition temperature of the induction solution was 39 ° C. The transmittance at this time changed sharply with temperature as shown in FIG.

  The induction solution temperature of the forward osmosis membrane device was adjusted to 45 ° C., and the inflow rate at the inlet was 8.0 L / min. As the liquid to be treated, a 2.5% sodium chloride aqueous solution whose concentration temperature was adjusted to 30 ° C. was used and allowed to flow into the forward osmosis membrane device at a flow rate of 3.3 L / min. The amount of water that passed through the membrane filtration device and moved to the induction solution was 0.9 L / min, the amount of the diluted induction solution flowing out from the outlet was 8.9 L / min, and the temperature was 43 ° C.

  When the diluted induction solution obtained by operating the apparatus for 10 minutes in a steady state was cooled to 35 ° C. and allowed to stand for 1 minute, the dissolved mixture of monoglycerin caprylate and polyethylene glycol aggregated and solidified by gravity. The liquid was separated, and an upper aqueous layer 20L and a lower oil layer 69L were obtained. The osmotic pressure of the water layer decreased to 0.2 MPa.

  Regeneration induction containing a mixture of monoglycerin caprylate and polyethylene glycol at a concentration of 400 g / L by combining the membrane concentrated water obtained by ultrafiltration of the aqueous layer and the oil layer obtained by gravity separation as described above. 80 L of the solution was obtained. Moreover, 9L of fresh water was obtained as an ultrafiltration membrane permeate.

  The concentration of the mixture of monoglycerin caprylate and polyethylene glycol contained in the fresh water was 100 mg / L or less.

  Membrane concentrated water containing a mixture of monoglycerin caprylate and polyethylene glycol at a concentration of 400 g / L could be returned to the original transparent induction solution by heating to 45 ° C.

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

Claims (10)

  Water to be treated and a derivative solution in which a temperature-sensitive substance that has a phase transition temperature, becomes hydrophilic when heated to a temperature higher than the phase transition temperature, and becomes hydrophobic when cooled below the phase transition temperature is dissolved in water. A forward osmosis step of contacting the water through the permeable membrane, transferring the water in the treated water to the induction solution through the semipermeable membrane to obtain a dilution induction solution diluted with water and membrane concentrated water, and the dilution induction solution Cooling to a temperature below the phase transition temperature, and solid-liquid separation of the thermosensitive substance cooled and hydrophobized in the cooling process from the dilution-inducing solution to obtain fresh water and a thermosensitive substance concentrate A water treatment method comprising: a separation step; and a heating step of regenerating the induction solution by heating the temperature-sensitive substance concentrate separated in the solid-liquid separation step to the phase transition temperature or higher.   2. The water treatment according to claim 1, wherein the solid-liquid separation means in the solid-liquid separation step is one of a filtration membrane capable of separating particles having a particle size of 100 nm or more, centrifugal separation, and specific gravity separation. Method.   The water treatment method according to claim 1 or 2, wherein the thermosensitive substance is a mixture of alcohol and fatty acid glycerin ester.   The water treatment method according to any one of claims 1 to 3, wherein a phase transition temperature of the temperature-sensitive substance is in a range of 30 ° C to 80 ° C.   The water treatment method according to any one of claims 1 to 4, wherein the temperature-sensitive substance concentrate separated in the solid-liquid separation step is used as a cold heat source in the cooling step.   The water treatment method according to any one of claims 1 to 5, wherein the dilution induction solution obtained in the forward osmosis step is used as a heat source in the heating step.   Water to be treated and a derivative solution in which a temperature-sensitive substance that has a phase transition temperature, becomes hydrophilic when heated to a temperature higher than the phase transition temperature, and becomes hydrophobic when cooled below the phase transition temperature is dissolved in water. A forward osmosis membrane treatment apparatus for contacting the membrane through the permeable membrane, transferring the water in the treated water to the induction solution through the semipermeable membrane, and obtaining a diluted induction solution and membrane concentrated water diluted with water; and the dilution A cooling means for cooling the induction solution below the phase transition temperature, and a thermosensitive substance that has been cooled and hydrophobized by the cooling means is separated from the diluted induction solution by solid-liquid separation to obtain fresh water and a thermosensitive substance concentrate. A water treatment comprising: a solid-liquid separation device; and a heating means for regenerating the induction solution by heating the temperature-sensitive substance concentrated liquid separated by the solid-liquid separation device to a temperature higher than the phase transition temperature. apparatus.   The water treatment apparatus according to claim 1, wherein the solid-liquid separation apparatus is an apparatus based on any one of a filtration membrane, centrifugal separation, and specific gravity separation capable of separating particles having a particle size of 100 nm or more.   The water treatment apparatus according to claim 1 or 2, wherein the temperature-sensitive substance is a mixture of alcohol and fatty acid glycerin ester.   The water treatment apparatus according to any one of claims 1 to 3, wherein a phase transition temperature of the temperature-sensitive substance is in a range of 30 ° C to 80 ° C.

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