JP2011067160A - Extraction method and extraction system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extraction method which permits the water content of microalgae to be completely extracted inexpensively in a short time and in a space-saving manner. <P>SOLUTION: The extraction method includes the step of separating a nutrient solution containing fine alga into the microalgae and the nutrient solution by centrifugal separation, the step of stirring and mixing the separated microalgae and a liquefied water-compatible solvent which is a gas at room temperature and at normal pressure under pressure and extracting a mixture of the microalgae from which the water content is extracted and the liquefied water-compatible solvent in which the water content is dissolved, the filtering step of filtering the mixture, and a first volatilization step of obtaining the microalgae dried by volatilizing the vaporizing matter of the water-compatible solvent from the obtained filtered matter. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method and system for extracting water or valuables from microalgae, and more particularly to a method and system for effectively extracting water or valuables from microalgae using a water-compatible solvent such as dimethyl ether. .

As one of the countermeasures against global warming, the utilization of microalgae that absorbs CO ₂ and grows rapidly has attracted attention (see, for example, Patent Document 1). Patent Document 1 discloses a novel strain of microalgae belonging to the genus Synechocystis that has high growth resistance, salt resistance, SO ₂ gas resistance and NO gas resistance.

In addition to absorbing CO ₂ , attempts have also been made to produce fuel and chemical raw materials (hereinafter referred to as valuable materials) from microalgae (see, for example, Patent Document 2). Patent Document 2 discloses a microalga belonging to the genus Chlamydomonas that grows at a salt concentration of seawater, accumulates starch in the cell, and produces ethanol from the starch in the cell by maintaining a dark and anaerobic atmosphere. Yes.

  In order to produce valuable materials from microalgae, not only a method for selecting and culturing microalgae, but also a method for efficiently extracting valuable materials from microalgae is required. In general, valuable substances are extracted from microalgae by a method such as a low-temperature pressing method, a high-temperature pressing method, or a solvent extraction method (see, for example, Patent Document 3). As an example of the solvent extraction method, Patent Document 3 describes a method of extracting hydrocarbons by immersing a microalga belonging to the genus Botriococcus in a non-aqueous compatible organic solvent that is not uniformly mixed with water. Yes. Examples of non-aqueous compatible organic solvents include ethyl acetate, butyl acetate, diethyl ether and the like.

  However, in the extraction method using a non-aqueous compatible solvent described in Patent Document 3, when a microalga that is insufficiently dried is used, moisture remains on the surface, so that the organic solvent effectively contacts the surface of the microalgae. It cannot be performed, and the extraction efficiency is deteriorated. Further, even if the method other than the solvent extraction is used, if the microalgae are not sufficiently dried, impurities such as moisture are mixed with the extracted valuables and the value thereof is lowered. Therefore, in order to increase the extraction efficiency of valuable materials and improve the value of the extracted valuable materials, an effective moisture extraction method capable of completely drying microalgae is also required.

  In the past, microalgae were dried by centrifugation or sun drying. Centrifugation is used not only for extraction from microalgae but also as a method for separating required microalgae from a mixture of various microalgae (see, for example, Patent Document 4).

  On the other hand, a method using a substance (dimethyl ether or the like) that is a gas at normal temperature and pressure has been developed as a dehydration method for water-containing substances in general (see, for example, Patent Document 5). In the dehydration method of Patent Document 5, liquefied dimethyl ether is brought into contact with a hydrated substance, and water in the hydrated substance is dissolved in the liquefied dimethyl ether for dehydration. As the contact method, a method in which liquefied dimethyl ether is brought into contact with the water-containing substance is used, and in particular, countercurrent contact in which the hydrated material is brought into contact with contact at a flow rate (100 L / hour) or more is preferable. Thereafter, by utilizing the gas-liquid phase transition phenomenon in which dimethyl ether becomes a gas at normal temperature and normal pressure, only dimethyl ether is selectively volatilized from the liquefied dimethyl ether in which water is dissolved to separate water and dimethyl ether.

  This method using liquefied dimethyl ether can also be used in a method for deoiling oil-containing substances (see, for example, Patent Document 6). In the deoiling method of Patent Document 6, an oil absorbent, metal, glass, ceramics, paper, or soil is exemplified as the oil-containing substance.

JP 08-56648 A Japanese Patent No. 3837589 Japanese Patent Application Laid-Open No. 07-75558 Japanese Patent Application Laid-Open No. 09-803 JP 2007-83122 A JP 2007-237129 A

  However, when water is extracted from microalgae, it is only possible to separate a certain proportion of water from the microalgae by centrifugation alone, and a large amount of water remains in the microalgae.

  In the sun drying, the moisture on the surface of the microalgae can be removed to some extent, but this requires a large area, and depending on the components contained in the microalgae, the quality may deteriorate due to ultraviolet irradiation. In addition, microalgae have a large amount of moisture not only on the cell surface but also inside the cell. For example, even if it is sun-dried, it is not easy to completely extract the moisture in the cell, and it takes a lot of time. Resulting in.

  Furthermore, the dehydration and deoiling methods using the solvents described in Patent Document 5 and Patent Document 6 are sufficient to remove moisture and oil as long as they are solid substances that allow a constant flow rate of solvent such as coal and wood to pass through stably. It can be extracted, but cannot be applied to fine substances such as microalgae that float in water.

  Based on the above problems, a first object of the present invention is to provide an extraction method and an extraction system capable of completely extracting moisture from microalgae in a short period of time, in a space-saving manner and at a low cost. In addition, a second object of the present invention is to provide an extraction method and an extraction system capable of completely extracting valuable materials from microalgae.

  In order to solve the above problems, an extraction method according to the present invention includes a separation step of separating a nutrient solution containing microalgae into microalgae and nutrient solution components by centrifugation, and the separated microalgae and normal temperature and normal pressure. An extraction step of stirring and mixing a liquefied product of a water-compatible solvent that is a gas under pressure to obtain a mixture of the microalgae from which water has been extracted and the liquefied product of the water-compatible solvent in which the water has been dissolved, A filtration step of filtering the mixture, and a first volatilization step of obtaining a dried microalga by volatilizing the water-compatible solvent from the obtained filtrate.

  By stirring and mixing the microalgae and the water-compatible solvent, not only the moisture on the cell surface of the microalgae but also the intracellular moisture can be sufficiently extracted by the osmotic pressure effect. Moreover, by using a water-compatible solvent that is a gas under normal temperature and normal pressure, the solvent can be easily separated from the filtrate after filtration, and dried microalgae can be obtained in a short time.

  Here, a second volatilization step of volatilizing the water-compatible solvent from the filtrate obtained in the filtration step, and a vaporized product of the water-compatible solvent volatilized in the first volatilization step and the second volatilization step. A recovery step of recovering, and a compression step of compressing the recovered vapor of the water-compatible solvent to obtain a liquefied product of the water-compatible solvent, wherein the extraction step was obtained in the compression step. The liquefied product of the water-compatible solvent may be reused.

  By recovering the vapor of the water-compatible solvent and reusing it in the extraction step, it is possible to reduce waste and reduce the environmental load, and to reduce the amount of solvent and extract water at low cost.

  Here, the microalga includes a valuable material that dissolves in the water-compatible solvent, and the mixture includes the microalga from which the moisture and the valuable material are extracted, and the water in which the moisture and the valuable material are dissolved. It is a mixture with a liquefied product of a compatible solvent, and may further comprise a valuable material separation step of separating the valuable material from the residual liquid remaining after volatilizing the aqueous compatible solvent from the filtrate in the second volatilization step. .

  By extracting valuable materials from the filtrate obtained in the filtration step, it is not necessary to provide a separate valuable material extraction step, and valuable materials can be extracted at low cost. Further, the valuable material is preferably an alcohol component or an oil component. This is because they have high added value and can be used for various purposes.

  Here, the nutrient solution is a culture solution of microalgae, and the culture solution separated in the separation step may be reused for culture of microalgae.

  By recovering the culture solution separated in the separation step and reusing it for culturing microalgae, it is possible to reduce waste and reduce the environmental burden.

  Here, the water-compatible solvent may be one or a mixture of two or more selected from dimethyl ether, ethyl methyl ether, formaldehyde, and acetaldehyde.

  Since the substances such as dimethyl ether listed here are easily available and relatively inexpensive, it is possible to extract water or valuables from microalgae at low cost.

  Here, in the filtration step, an upper layer may be taken out from the mixed solution mixed in the extraction step and filtered.

  Substances such as dimethyl ether listed as water-compatible solvents have a liquid density lower than that of water. For this reason, among these liquefied products, microalgae with a high water content are initially settled due to the difference in specific gravity, and float as the intracellular water is extracted by the osmotic pressure effect. Therefore, by transferring the upper layer of the mixed solution, only the microalga from which the intracellular moisture has been sufficiently extracted can be selectively extracted, and the extraction efficiency can be improved.

  Furthermore, the extraction system according to the present invention includes a centrifugal separator that separates a nutrient solution containing microalgae into microalgae and nutrient solution components, and the separated microalgae and a water-compatible solvent that is gaseous under normal temperature and normal pressure. The liquefied product was stirred and mixed under pressure, an extraction tank for obtaining a mixture of the microalga from which water was extracted and the liquefied product of the water-compatible solvent in which the water was dissolved, and the mixture was filtered and obtained. And a filter for obtaining a dried microalga by volatilizing the water-compatible solvent from the filtrate.

  According to the extraction method and the extraction system of the present invention, moisture can be completely extracted from microalgae in a short period of time, in a space-saving manner and at a low cost. Similarly, according to the extraction method and the extraction system according to the present invention, valuable materials can be completely extracted from microalgae.

It is a block diagram of the extraction system concerning 1st embodiment of this invention. It is a block diagram of the extraction system concerning 2nd embodiment of this invention. It is a detailed block diagram of a solvent circulation process among the extraction systems concerning 2nd embodiment of this invention. It is a flowchart showing the extraction method concerning 3rd embodiment of this invention.

  EMBODIMENT OF THE INVENTION The form for implementing this invention is demonstrated in detail, referring an accompanying drawing below. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified.

[First embodiment]
FIG. 1 is a configuration diagram of an extraction system according to the first embodiment of the present invention. The extraction system 10 according to the present embodiment stirs and mixes a centrifugal separator 11 that separates a nutrient solution containing microalgae into microalgae and nutrient solution components, and the separated microalgae and a liquefied product of a water-compatible solvent. And a filter 13 for filtering the mixture and volatilizing the water-compatible solvent from the filtrate to obtain dried microalgae. Hereinafter, each component will be described in detail.

  In the centrifuge 11, the nutrient solution containing microalgae is separated into microalgae and nutrient solution components. In the centrifugal separation, a nutrient solution containing microalgae is placed in a container that rotates at high speed, and is separated into microalgae and nutrient solution components due to the difference in specific gravity. What is necessary is just to set a rotational speed suitably from the range which can isolate | separate a nutrient solution component effectively. Generally, it is 500-10000 rpm, and 1000-5000 rpm is more preferable among these. Normally, even if centrifugation is performed, the moisture in the microalgae cells (content ratio of 80 to 90% by weight) cannot be separated (dehydrated).

  Here, the microalgae are small plants that inhabit micro-sized freshwater or seawater, and are generally called microalgae. Among these, in particular, the present embodiment is directed to microalgae capable of producing valuable materials. Examples of such microalgae include Botryococcus, Chlorella, Donariella, and Chlamydomonas, but are not limited to these and include a wide range of microalgae that can produce valuable materials.

  The nutrient solution is a liquid in the environment where microalgae inhabit. If microalgae inhabit freshwater and seawater, freshwater and seawater correspond to nutrient solutions. If microalgae are cultured in the culture solution, the culture solution corresponds to the nutrient solution.

  In the extraction tank 12, the separated microalgae and a liquefied product of a water-compatible solvent that is a gas at normal temperature and pressure are stirred and mixed under pressure. By contacting the microalgae with the water-compatible solvent, the water contained in the microalgae is dissolved in the water-compatible solvent, and water is effectively extracted from the microalgae. As a result, a mixture of a microalga from which water has been extracted and a liquefied product of a water-compatible solvent in which the water has been dissolved is obtained.

  Here, the reason why the microalgae and the water-compatible solvent are stirred and mixed is that not only the moisture on the cell surface of the microalgae but also the intracellular moisture is sufficiently extracted by the osmotic pressure effect. In addition, since the cell wall of a micro algae will be torn and it will become impossible to collect | recover as a micro algae if a stirring speed is too high, it is preferable to set a stirring speed comparatively low.

  In this embodiment, a water-compatible solvent that is a gas at normal temperature and pressure is used as the extraction solvent. Here, the normal temperature represents a temperature close to the outside air temperature, generally means a range of -10 to 50 ° C., and the normal pressure means a range around 1 atm.

  Examples of such water-compatible solvents include dimethyl ether, ethyl methyl ether, formaldehyde, and acetaldehyde. These may be used alone or in combination of two or more. Since the substances listed here are easily available and relatively inexpensive, microalgae can be dried at low cost.

  Among those exemplified, dimethyl ether alone or a mixture of dimethyl ether and another substance is preferably used. Dimethyl ether is chemically stable and has low toxicity. In addition, it has a low boiling point (−24.8 ° C. at 1 atm) and is a gas at room temperature, but also has a low saturated vapor pressure (0.62 MPa at 25 ° C.) and easily liquefies when pressurized.

  The amount of the water-compatible solvent to be mixed with the microalgae is preferably set to be equal to or higher than the theoretical amount that can dissolve all the water contained in the microalgae. This is because the water contained in the microalgae can be completely extracted. Dimethyl ether liquefied product has a saturated solubility of water of 6.7 wt% at 20 ° C. Under this condition, the theoretical amount capable of dissolving all 1 g of water is 14.9 g. In practice, it is preferable to use a water-compatible solvent 2 to 10 times the theoretical amount.

  Moreover, the inside of the extraction tank 12 is pressurized so that it may become more than the saturated vapor pressure of a water-compatible solvent. By pressurization, the water-compatible solvent can be stably maintained in a liquefied state, and the osmotic pressure effect is enhanced and the extraction of moisture from the microalgae is promoted. However, it is preferable to set the pressure in the extraction tank 12 to be slightly higher than the saturated vapor pressure of the water-compatible solvent, avoiding excessively high pressure. This is because if the pressure is excessively high, the cost of making the container pressure-proof is increased and the cell wall of the microalgae may be destroyed.

  In the filter 13, the mixture mixed in the extraction tank 12 is filtered, and the vaporized water-compatible solvent is volatilized from the obtained filtrate. As a result, dried microalgae can be obtained.

  The pressure in the filter 13 is reduced until the water-miscible solvent can be completely volatilized until it becomes equal to or lower than the saturated vapor pressure. In this embodiment, since a water-compatible solvent having a low saturated vapor pressure is used, the solvent can be easily separated from the filtrate by slightly reducing the pressure in the filter 13, and a dried microalga can be obtained in a short time. Can do. At this time, the pressure in the filter 13 is preferably reduced to normal pressure. This is because the dried microalgae are easier to remove from the filter 13 under normal pressure.

  A filter is attached to the filter 13, and the mixture is filtered with this filter. What is necessary is just to set the raw material and fineness of a filter suitably from the magnitude | size of the micro algae which are filtration objects. For example, a membrane filter having a pore diameter of several tens of μm can be used.

  As described above, according to the extraction system according to the first embodiment, moisture can be completely extracted from microalgae in a short period of time, in a space-saving manner and at a low cost.

[Second Embodiment]
FIG. 2 is a configuration diagram of an extraction system according to the second embodiment. In addition to the first embodiment shown in FIG. 1, the extraction system 10 according to the second embodiment includes a culture solution circulation process 20 that collects and reuses the culture solution, and a water-compatible solvent that is collected and reused. And a solvent circulation process 30 to be used. In FIG. 2 and subsequent figures, the circulation system of the vaporized product (gas) is represented by a dotted line, and the circulation system of the liquefied product (liquid) and the solidified product (solid) is represented by a solid line.

  The culture solution circulation process 20 is mainly composed of a culture tank 21 for culturing microalgae and the centrifuge 11 described above. In addition, 2nd embodiment demonstrates as an object the form which culture | cultivates a micro algae in the culture tank 21 using a culture solution.

  A culture solution containing microalgae is sent from the culture tank 21 to the centrifuge 11, and is separated into microalgae and culture solution by the centrifuge 11. The separated culture solution is returned to the culture tank 21 and reused. By collecting the culture solution and reusing it for culturing microalgae, it is possible to reduce waste and reduce the environmental burden.

  The solvent circulation process 30 will be described with reference to FIG. FIG. 3 is a detailed configuration diagram of a solvent circulation process in the extraction system according to the second embodiment. In this process, in addition to the extraction tank 12 and the filter 13, the volatilization tank 31 that volatilizes the vapor of the water-compatible solvent from the filtrate, and the gas of the water-compatible solvent that has volatilized from the filter 13 and the volatilization tank 31 are used. A recovery tank 32 that recovers the chemicals, and a compressor 33 that compresses the recovered water-compatible solvent vapor to obtain a liquefied water-compatible solvent.

  The water-soluble solvent liquefaction obtained by the compressor 33 is reused in the extraction tank 12. By recovering the vaporized water-compatible solvent and reusing it in the extraction tank 12, it is possible to reduce waste and reduce the environmental burden, and also reduce the amount of solvent and the extraction cost from microalgae. .

  The processing flow in the solvent circulation process 30 is as follows. First, the microalgae separated by the centrifuge 11 are transferred to the extraction tank 12. After completion of the transfer, the inside of the extraction tank is pressurized with a pressurizing pump (not shown), and after the pressurization is completed, the first on-off valve 41 is opened and the liquefied product of the water-compatible solvent obtained by the compressor 33 is injected.

  After the injection is completed, the first on-off valve 41 is closed, the mixture is stirred and mixed in the extraction tank, the second on-off valve 42 is opened, and the stirred and mixed mixture is transferred to the filter 13 and filtered. At this time, after stirring and mixing the mixture, the upper layer of the mixed solution is preferably transferred to the filter 13 and filtered.

  The liquid density of dimethyl ether, ethyl methyl ether, formaldehyde and acetaldehyde exemplified as the water-compatible solvent is smaller than that of water. For this reason, in the liquefied product of the water-compatible solvent, the microalgae having a high water content are initially settled due to the difference in specific gravity, and float as the intracellular moisture is extracted by the osmotic pressure effect. Therefore, by transferring the upper layer of the mixed solution to the filter 13, only the microalga from which the intracellular moisture has been sufficiently extracted can be selectively extracted, and the extraction efficiency can be improved.

  The upper layer refers to a layer excluding the lower layer in which microalgae with a high water content settle, and specifically, an arbitrary layer selected from the upper half of the mixture that is allowed to stand in the extraction tank. Refers to that.

  After the transfer of the mixed liquid to the filter 13 is completed, the second on-off valve 42 is closed and the third on-off valve 43 is opened to transfer the filtrate to the volatilization tank 31. Thereafter, the third on-off valve 43 is closed and the fourth on-off valve 44 and the fifth on-off valve 45 are opened, and the inside of the filter 13 and the volatilization tank 31 is decompressed to volatilize the vaporized water-compatible solvent. The vaporized water-compatible solvent vaporized is collected in the collection tank 32, and the fourth on-off valve 44 and the fifth on-off valve 45 are closed after the collection is completed. The recovered vapor of the water-compatible solvent is compressed by the compressor 33 to become a liquefied product and used again in the extraction tank 12.

  Further, the water remaining in the volatilization tank 31 is drained by opening the sixth on-off valve 46.

[Third embodiment]
The third embodiment is directed to a case where the microalga includes a valuable material that dissolves in the water-compatible solvent. Such valuables include a wide range of substances that can be used as raw materials for fuels and chemical substances, with alcohol or oil components being particularly preferred. This is because the alcohol component or oil component has high added value and can be used for various applications. Examples of alcohol components include methanol, ethanol, lower alcohols, and higher alcohols.

Examples of the oil component include fats and oils and hydrocarbons, which may be liquid or solid at room temperature, and may be volatile or non-volatile. Examples of the fats and oils include triglycerides, diglycerides, and monoglycerides, and the constituent fatty acids include fatty acids selected from the group consisting of C12 to C28 fatty acids (myristolic acid, palmitic acid, palmitoleic acid, oleic acid, stearic acid, linoleic acid, Linolenic acid and the like). Examples of hydrocarbons mainly include C16-C33 alkadienes and alkatrienes, and terpenes such as triterpenes (squalene), tetraterpenes (lycopadiene), and botryococcenes.

  Since the valuable material can be dissolved in the water-compatible solvent, the mixture mixed in the extraction tank 12 includes liquefaction of the water and the microalgae from which the valuable material is extracted, and the water-compatible solvent in which the water and the valuable material are dissolved. Things are included.

  In the volatilization tank 31, the water-compatible solvent is volatilized from the filtrate obtained by the filter 13, and the valuable material is extracted by separating the valuable material from the remaining liquid. By extracting valuables from the filtrate, it is not necessary to provide a separate valuable extraction process, and valuables can be extracted from microalgae at low cost.

  A known extraction method can be used as a method for extracting valuable materials from the residual liquid. The residual liquid may be allowed to stand to separate water and valuables due to the difference in specific gravity. As described in Patent Document 3, the valuables are selectively separated using a non-aqueous compatible organic solvent. May be.

  Alternatively, valuable substances can be extracted from the residual liquid by utilizing the characteristics of the water-compatible solvent used for the extraction of moisture. The process is as follows. First, a part of the water-compatible solvent is volatilized from the residual liquid, and then left to stand to form a two-liquid phase of a liquefied phase and an aqueous phase of the water-compatible solvent. There is no limit to the amount of valuables that can be dissolved in a water-compatible solvent, but since there is a limit to the amount of saturated water that can be dissolved, the amount of water-miscible solvent decreases, so that water that cannot be dissolved precipitates. Is formed. When the water of the aqueous phase is drained, a liquefied phase of an aqueous compatible solvent in which only valuable materials are dissolved remains. When the water-compatible solvent is volatilized from here, valuable materials with high purity can be easily extracted. This method of separating valuables using a water-compatible solvent can be suitably used particularly when the valuables are water-soluble.

  Next, an extraction method for extracting moisture and valuables from microalgae in the third embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing the extraction method according to the third embodiment.

  First, a nutrient solution containing microalgae is separated into microalgae and nutrient solution components by centrifugation (separation step S1). The separated microalgae and the liquefied product of the water-compatible solvent that is a gas at normal temperature and pressure are stirred and mixed under pressure (extraction step S2). The mixture of the mixed microalga and the liquefied product of the water-compatible solvent is filtered (filtration step S3). The filtrate and the filtrate are selected (S4), and the water-compatible solvent is volatilized from the filtrate (first volatilization step S5). Volatilized vaporized substances and residual solid substances are selected (S6), and dried microalgae are obtained from the solid substances. The steps so far are the same as in the first embodiment.

  In the second and third embodiments, the water-compatible solvent is also volatilized from the filtrate (second volatilization step S7), and the vaporized material and the residual liquid are selected (S8). Next, the vaporized water-compatible solvent selected in the selection steps S6 and S8 is recovered (recovery step S9). The recovered water-compatible solvent vaporized product is compressed to obtain a water-compatible solvent liquefied product (compression step S10), and the obtained water-compatible solvent liquefied product is reused in the extraction step S2.

  Moreover, valuables are separated from the residual liquid selected in the sorting step S8 (valuable material separation step S11) to obtain valuables extracted from the microalgae.

  INDUSTRIAL APPLICABILITY The extraction method and extraction system of the present invention can be used in a process for extracting valuable substances from microalgae and a process for drying microalgae in the preceding stage in the manufacturing process of valuable substances using microalgae.

DESCRIPTION OF SYMBOLS 10 ... Extraction system, 11 ... Centrifuge, 12 ... Extraction tank, 13 ... Filter
20 ... Culture medium circulation process, 21 ... Culture tank,
30 ... Solvent circulation process, 31 ... Volatilization tank, 32 ... Recovery tank, 33 ... Compressor,
DESCRIPTION OF SYMBOLS 41 ... First on-off valve, 42 ... Second on-off valve, 43 ... Third on-off valve, 44 ... Fourth on-off valve, 45 ... Fifth on-off valve, 46 ... Sixth on-off valve

Claims (13)

A separation step of separating the nutrient solution containing microalgae into microalgae and nutrient solution components by centrifugation;
The separated microalga and the liquefied product of the water-compatible solvent that is a gas at normal temperature and pressure are stirred and mixed under pressure, and the microalga from which the moisture is extracted and the liquefied product of the water-compatible solvent in which the water is dissolved An extraction step to obtain a mixture with
A filtration step of filtering the mixture;
A first volatilization step comprising obtaining a dried microalga by volatilizing the water-compatible solvent from the obtained filtrate. A second volatilization step of volatilizing the water-compatible solvent from the filtrate obtained in the filtration step;
A recovery step of recovering the vaporized water-compatible solvent volatilized in the first volatilization step and the second volatilization step;
A compression step of compressing the recovered vapor of the water-compatible solvent to obtain a liquefied product of the water-compatible solvent,
2. The extraction method according to claim 1, wherein in the extraction step, a liquefied product of the water-compatible solvent obtained in the compression step is reused. The microalgae contains valuables that dissolve in the water-compatible solvent,
The mixture is a mixture of a microalga from which moisture and valuables are extracted and a liquefied product of the water-compatible solvent in which the moisture and valuables are dissolved,
The extraction method according to claim 2, further comprising a valuable material separation step of separating the valuable material from the residual liquid remaining after volatilizing the water-compatible solvent from the filtrate in the second volatilization step. The extraction method according to claim 3, wherein the valuable material is an alcohol component or an oil component. The nutrient solution is a culture solution of microalgae,
The extraction method according to any one of claims 1 to 4, wherein the culture solution separated in the separation step is reused for cultivation of microalgae. 6. The extraction method according to claim 1, wherein the water-compatible solvent is one or a mixture of two or more selected from dimethyl ether, ethyl methyl ether, formaldehyde, and acetaldehyde. The extraction method according to claim 6, wherein, in the filtration step, an upper layer is taken out from the mixed liquid mixed in the extraction step and filtered. A centrifuge for separating a nutrient solution containing microalgae into microalgae and nutrient components;
The separated microalga and the liquefied product of the water-compatible solvent that is a gas at normal temperature and pressure are stirred and mixed under pressure, and the microalga from which the moisture is extracted and the liquefied product of the water-compatible solvent in which the water is dissolved An extraction tank to obtain a mixture of
An extraction system comprising: a filter for filtering the mixture and volatilizing the water-compatible solvent from the obtained filtrate to obtain dried microalgae. A volatilization tank for volatilizing the water-compatible solvent from the filtrate obtained by the filter;
A recovery tank for recovering the vaporized water-compatible solvent volatilized in the filter and the volatilization tank;
A compressor that compresses the recovered vapor of the water-compatible solvent to obtain a liquefied product of the water-compatible solvent; and
The extraction system according to claim 8, wherein in the extraction tank, a liquefied product of the water-compatible solvent obtained by the compressor is reused. The microalgae contains valuables that dissolve in the water-compatible solvent,
The mixture is a mixture of a microalga from which moisture and valuables are extracted and a liquefied product of the water-compatible solvent in which the moisture and valuables are dissolved,
The extraction system according to claim 9, wherein in the volatilization tank, the water-compatible solvent is volatilized from the filtrate and the valuable material is separated from the remaining liquid. The extraction system according to claim 10, wherein the valuable material is an alcohol component or an oil component. The extraction system according to any one of claims 8 to 11, wherein the water-compatible solvent is one or a mixture of two or more selected from dimethyl ether, ethyl methyl ether, formaldehyde, and acetaldehyde. The extraction system according to claim 12, wherein the filter removes an upper layer from the mixed solution mixed in the extraction tank and filters the mixture.