Membrane separation system and method for operating membrane separation device

Abstract

Provided is a membrane separation system with which a non-permeable fluid that is sufficiently suitable for reuse can be obtained by treatment using a pervaporation membrane. This membrane separation system (100) is provided with a membrane separation device (10). The membrane separation device 10 has a pervaporation membrane 11. The pervaporation membrane 11 separates a fermentation broth S containing a volatile organic compound C and a microorganism that produces the organic compound C into a permeate fluid and a non-permeate fluid. The membrane separation system (100) adjusts the temperature of the membrane separation device (10) such that the absolute value of the difference between the temperature T1 (DEG C) of the fermentation broth (S) supplied to the membrane separation device (10) and the temperature T2 (DEG C) of the impermeable fluid discharged from the membrane separation device (10) is less than 10 DEG C.

Description

Technical Field

[0001] The present invention relates to a membrane separation system and an operating method of a membrane separation device. Background Art

[0002] A method for producing volatile organic compounds (fermented products) such as alcohols by fermenting carbon sources such as glucose using microorganisms has been developed. The fermentation of the carbon source is carried out, for example, in an aqueous solution. In this method, if the content of the fermented product in the aqueous solution increases, the fermentation based on the microorganism is sometimes stopped. In order to continuously produce the fermented product based on the microorganism, it is necessary to separate the fermented product from the aqueous solution.

[0003] As an example of a method for separating volatile organic compounds from an aqueous solution containing the organic compounds, a pervaporation method (pervaporation method) using a pervaporation membrane can be cited. The pervaporation method is suitable for separating volatile organic compounds from aqueous solutions containing various substances. Compared with the distillation method, the pervaporation method also tends to be able to suppress energy consumption and carbon dioxide emissions. By combining a membrane separation device for performing the pervaporation method with a fermentation tank for producing fermented products, fermented products can be continuously produced. For example, Patent Document 1 discloses a membrane separation system that combines a membrane separation device and a fermentation tank. Patent Document 1 discloses that the fermented liquid (non-permeable fluid) that has not passed through the pervaporation membrane is returned to the fermentation tank, thereby reusing the non-permeable fluid.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 4048279 Summary of the invention

[0007] Problems to be solved by the invention

[0008] When a feed liquid is separated into a permeated fluid and a non-permeated fluid using a pervaporation membrane, the permeated fluid is usually obtained in a gaseous state. That is, in the pervaporation method, a gaseous permeated fluid is obtained by vaporizing the feed liquid that has passed through the pervaporation membrane. Since the vaporization of the feed liquid usually requires thermal energy, a large temperature change occurs in the treated feed liquid (non-permeated fluid).

[0009] When a fermentation liquid containing a fermented product and a microorganism that generates the fermented product is used as a supply liquid, there is a tendency to apply stress to the microorganisms in the fermentation liquid due to the above-mentioned temperature change. As a result, in the fermentation liquid, the number of microorganisms that can generate the fermented product decreases, and the microorganisms die depending on the situation. If a fermentation liquid (non-permeable fluid) that produces a large temperature change is supplied to the fermentation tank, the fermentation liquid stored in the fermentation tank also undergoes a temperature change, and sometimes the microorganisms in the fermentation liquid decrease. As such, in the past, it cannot be said that the fermentation liquid (non-permeable fluid) treated by the permeation vaporization membrane is fully suitable for reuse.

[0010] Therefore, an object of the present invention is to provide a membrane separation system capable of obtaining a non-permeated fluid that is sufficiently suitable for reuse through treatment using a pervaporation membrane.

[0011] Means for solving problems

[0012] The present invention provides a membrane separation system, which is a membrane separation system comprising a membrane separation device, wherein:

[0013] The membrane separation device comprises a pervaporation membrane,

[0014] The pervaporation membrane separates a fermentation liquid containing volatile organic compounds and microorganisms producing the organic compounds into a permeated fluid and a non-permeated fluid.

[0015] The membrane separation system adjusts the temperature of the membrane separation device so that the absolute value of the difference between the temperature T1 (°C) of the fermentation liquid supplied to the membrane separation device and the temperature T2 (°C) of the non-permeated fluid discharged from the membrane separation device becomes less than 10°C.

[0016] In addition, the present invention also provides an operating method of a membrane separation device, which is an operating method of a membrane separation device having a pervaporation membrane, and the operating method comprises:

[0017] a supplying step of supplying a fermentation liquid containing a volatile organic compound and a microorganism producing the organic compound to the membrane separation device; and

[0018] a membrane separation step of separating the fermentation liquid into a permeable fluid and a non-permeable fluid by using the pervaporation membrane;

[0019] The membrane separation step is performed while the temperature of the membrane separation device is adjusted so that the absolute value of the difference between the temperature T1 (°C) of the fermentation liquid supplied in the supply step and the temperature T2 (°C) of the non-permeable fluid discharged from the membrane separation device becomes lower than 10°C.

[0020] Effects of the Invention

[0021] According to the present invention, it is possible to provide a membrane separation system capable of obtaining a non-permeated fluid sufficiently suitable for reuse through treatment using a pervaporation membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] [ Figure 1 ] is a schematic diagram showing an example of a membrane separation system according to embodiment 1.

[0023] [ Figure 2 ] is a schematic cross-sectional view showing an example of a heating section provided in a membrane separation system.

[0024] [ Figure 3 ] is a schematic cross-sectional view showing an example of a membrane separation device.

[0025] [ Figure 4 ] is a schematic cross-sectional view of a pervaporation membrane included in a membrane separation device.

[0026] [ Figure 5 ] is a developed stereoscopic view schematically showing another example of a membrane separation device.

[0027] [ Fig. 6A ] is a schematic diagram showing a modified example of the membrane separation system.

[0028] [ Figure 6B ] is a schematic diagram showing a modified example of the membrane separation system.

[0029] [ Figure 7 ] is a schematic diagram showing an example of a membrane separation system according to embodiment 2. DETAILED DESCRIPTION

[0030] A membrane separation system according to a first aspect of the present invention is a membrane separation system comprising a membrane separation device, wherein:

[0031] The membrane separation device has a pervaporation membrane.

[0032] The pervaporation membrane separates the fermentation liquid containing the volatile organic compounds and the microorganisms producing the organic compounds into a permeated fluid and a non-permeated fluid.

[0033] The membrane separation system adjusts the temperature of the membrane separation device so that the absolute value of the difference between the temperature T1 (°C) of the fermentation liquid supplied to the membrane separation device and the temperature T2 (°C) of the non-permeated fluid discharged from the membrane separation device becomes lower than 10°C.

[0034] In the second aspect of the present invention, for example, in the membrane separation system of the first aspect, the temperature of the membrane separation device is adjusted so that the absolute value becomes lower than 3°C.

[0035] In a third aspect of the present invention, for example, in the membrane separation system of the first or second aspect, the temperature T1 is 30°C to 75°C.

[0036] In a fourth aspect of the present invention, for example, the membrane separation system according to any one of the first to third aspects further includes a heating unit that heats the membrane separation device.

[0037] In a fifth aspect of the present invention, for example, in the membrane separation system of any one of the first to fourth aspects, a content rate of the organic compound in the permeated fluid is higher than a content rate of the organic compound in the fermentation liquid.

[0038] In a sixth aspect of the present invention, for example, in the membrane separation system according to any one of the first to fifth aspects, the organic compound is an alcohol.

[0039] In a seventh aspect of the present invention, for example, the membrane separation system according to any one of the first to sixth aspects further includes a tank for storing the fermentation liquid to be supplied to the membrane separation device.

[0040] In an eighth aspect of the present invention, for example, the membrane separation system of the seventh aspect further comprises a non-permeated fluid discharge path connected to the membrane separation device and for discharging the non-permeated fluid from the membrane separation device.

[0041] The non-permeated fluid discharge path is connected to the tank.

[0042] In a ninth aspect of the present invention, for example, the membrane separation system of any one of the first to eighth aspects further includes a second membrane separation device having a second pervaporation membrane for separating the permeated fluid into a second permeated fluid and a second non-permeated fluid.

[0043] In a tenth aspect of the present invention, for example, in the membrane separation system of the ninth aspect, the temperature of the second non-permeated fluid discharged from the second membrane separation device is 30°C to 75°C.

[0044] In the eleventh aspect of the present invention, for example, the membrane separation system of the ninth or tenth aspect further comprises:

[0045] a tank for storing the fermentation liquid to be supplied to the membrane separation device; and

[0046] a second non-permeated fluid discharge path connected to the second membrane separation device and used to discharge the second non-permeated fluid from the second membrane separation device,

[0047] The second non-permeated fluid discharge path is connected to the tank.

[0048] A method for operating a membrane separation device according to a twelfth aspect of the present invention is a method for operating a membrane separation device having a pervaporation membrane, the method comprising:

[0049] a supplying step of supplying a fermentation liquid containing a volatile organic compound and a microorganism producing the organic compound to the membrane separation device; and

[0050] a membrane separation step of separating the fermentation liquid into a permeable fluid and a non-permeable fluid by the pervaporation membrane;

[0051] The membrane separation step is performed while the temperature of the membrane separation device is adjusted so that the absolute value of the difference between the temperature T1 (°C) of the fermentation liquid supplied in the supply step and the temperature T2 (°C) of the non-permeable fluid discharged from the membrane separation device becomes lower than 10°C.

[0052] Hereinafter, the present invention will be described in detail, but the following description is not intended to limit the present invention to specific embodiments.

[0053] <Implementation Method 1>

[0054] like Figure 1 As shown, the membrane separation system 100 of embodiment 1 includes a membrane separation device 10. The membrane separation device 10 includes a pervaporation membrane, and a supply space and a permeation space separated by the pervaporation membrane. The pervaporation membrane can separate a fermentation liquid S containing a volatile organic compound C and a microorganism that produces the organic compound C into a permeated fluid and a non-permeated fluid. It should be noted that the microorganism that produces the organic compound C is typically a bacterium.

[0055] The membrane separation system 100 adjusts the temperature of the membrane separation device 10 so that the absolute value (|T1-T2|) of the difference between the temperature T1 (°C) of the fermentation liquid S supplied to the membrane separation device 10 and the temperature T2 (°C) of the non-permeated fluid discharged from the membrane separation device 10 becomes lower than 10°C.

[0056] As described above, the membrane separation device 10 is a device that performs membrane separation on the fermentation liquid S using a pervaporation membrane. Typically, the pervaporation membrane is a membrane that preferentially permeates the organic compound C contained in the fermentation liquid S. Therefore, the content of the organic compound C in the permeated fluid separated by the pervaporation membrane is higher than that in the fermentation liquid S. On the other hand, the content of the organic compound C in the non-permeated fluid is lower than that in the fermentation liquid S.

[0057] The membrane separation system 100 further includes a heating unit 50 for heating the membrane separation device 10. The heating unit 50 is located near the membrane separation device 10, for example, in direct contact with the membrane separation device 10. The heating unit 50 may surround the membrane separation device 10. The membrane separation system 100 may also include a heat pump, and a heat exchanger included in the heat pump may function as the heating unit 50. The heating unit 50 may also be configured to utilize heat (waste heat) obtained by other heat exchangers included in the membrane separation system 100 (for example, a heat exchanger disposed in the permeate fluid discharge path 62 described later). It should be noted that the heating unit 50 may also be a heater such as an electric heater.

[0058] The membrane separation system 100 includes a membrane separation device 10 and a tank 20. The tank 20 stores a fermentation liquid S to be supplied to the membrane separation device 10. The tank 20 may be a fermentation tank for producing an organic compound C by fermentation of a carbon source by microorganisms.

[0059] The membrane separation system 100 further includes a fermentation liquid supply path 60, a non-permeable fluid discharge path 61, and a permeable fluid discharge path 62. The fermentation liquid supply path 60 is a path for supplying the fermentation liquid S from the tank 20 to the membrane separation device 10 during operation, and is connected to the outlet 21 of the tank 20 and the supply space inlet 13a of the membrane separation device 10. The fermentation liquid supply path 60 is provided with, for example, a pump 40 for controlling the flow rate of the fermentation liquid S. A temperature sensor (not shown) for measuring the temperature T1 of the fermentation liquid S supplied to the membrane separation device 10 may also be provided on the fermentation liquid supply path 60. The temperature sensor is, for example, located between the pump 40 and the membrane separation device 10, preferably located near the supply space inlet 13a of the membrane separation device 10.

[0060] The non-permeable fluid discharge path 61 is a path for discharging the non-permeable fluid from the membrane separation device 10 during operation, and is connected to the supply space outlet 13b of the membrane separation device 10. The non-permeable fluid discharge path 61 is provided with, for example, a pump 41 for controlling the flow rate of the non-permeable fluid. It should be noted that the pump 41 may not be provided on the non-permeable fluid discharge path 61. A temperature sensor (not shown) for measuring the temperature T2 of the non-permeable fluid discharged from the membrane separation device 10 may also be provided on the non-permeable fluid discharge path 61. The temperature sensor is, for example, located between the membrane separation device 10 and the pump 41, preferably located near the supply space outlet 13b of the membrane separation device 10.

[0061] The non-permeated fluid discharge path 61 may be connected to the inlet 22 of the tank 20, and may be configured to deliver the non-permeated fluid to the tank 20 during operation. That is, during operation, the non-permeated fluid may be mixed with the fermentation liquid S in the tank 20 and circulate in the fermentation liquid supply path 60 and the non-permeated fluid discharge path 61. When the non-permeated fluid is delivered to the tank 20, the fermentation liquid S and the non-permeated fluid are mixed in the tank 20, and the content of the organic compound C in the fermentation liquid S is reduced. When the tank 20 is a fermentation tank, the reduction in the content of the organic compound C in the fermentation liquid S can suppress the stop of fermentation by microorganisms, thereby enabling continuous production of fermented products.

[0062] The permeate fluid discharge path 62 is a path for discharging the permeate fluid from the membrane separation device 10 during operation, and is connected to the permeate space outlet 14a of the membrane separation device 10. For example, a decompression device 42 is arranged on the permeate fluid discharge path 62. The decompression device 42 can decompress the permeate space of the membrane separation device 10. The decompression device 42 is preferably a vacuum device such as a vacuum pump. The vacuum pump is typically a gas-transporting vacuum pump, and a reciprocating vacuum pump, a rotary vacuum pump, etc. can be cited. As a reciprocating vacuum pump, a diaphragm type and a swing piston type vacuum pump can be cited. As a rotary vacuum pump, a liquid seal pump; an oil rotary pump (rotary pump); a mechanical booster pump; various dry pumps such as Roots type, claw type, screw type, turbine type, and vortex type can be cited. The pump as the decompression device 42 can also be equipped with a variable speed mechanism for changing the rotation speed, etc. An example of a variable speed mechanism is an inverter that drives the motor of the pump. By controlling the rotation speed of the pump using a variable speed mechanism, etc., the pressure of the permeation space of the membrane separation device 10 can be appropriately adjusted.

[0063] A heat exchanger for cooling the permeated fluid may also be arranged in the permeated fluid discharge path 62. The permeated fluid of the gas can be condensed by the heat exchanger. The heat exchanger is, for example, a gas-liquid heat exchanger that generates heat exchange between a cooling medium such as an antifreeze liquid and the permeated fluid of the gas. The heat exchanger may be located between the membrane separation device 10 and the pressure reducing device 42 (on the upstream side of the pressure reducing device 42), or between the pressure reducing device 42 and the recovery unit 30 described later (on the downstream side of the pressure reducing device 42).

[0064] The membrane separation system 100 further includes a recovery unit 30. The recovery unit 30 recovers the permeated fluid sent from the membrane separation device 10 and can, for example, store the permeated fluid. The recovery unit 30 is, for example, a tank for storing the permeated fluid. The inlet 31 of the recovery unit 30 is connected to a permeated fluid discharge path 62.

[0065] The membrane separation system 100 may further include a controller 45 for controlling the various components of the membrane separation system 100. The controller 45 is, for example, a DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an operation circuit, a storage device, etc. A program for properly operating the membrane separation system 100 is stored in the controller 45. For example, the controller 45 can control the operation of the heating unit 50 to adjust the temperature of the membrane separation device 10.

[0066] Unless otherwise specified, each path of the membrane separation system 100 is constituted by a pipe made of metal or resin, for example.

[0067] [Heating unit]

[0068] like Figure 2 As shown, the heating unit 50 may also be configured to have a main body 51 having a housing space 54, into which a heat medium 55 for heating the membrane separation device 10 is introduced. Specifically, in the heating unit 50, the main body 51 includes an inner wall 52 and an outer wall 53. The housing space 54 is formed between the inner wall 52 and the outer wall 53. The shape of each of the inner wall 52 and the outer wall 53 is, for example, a cylindrical shape, or a cylindrical shape. The inner wall 52 surrounds the membrane separation device 10, for example, and is directly connected to the membrane separation device 10.

[0069] For example, an opening 56a and an opening 56b located above the opening 56a are formed in the outer wall 53. The opening 56a is connected to a heat medium supply path 57 for supplying the heat medium 55 to the storage space 54, and functions as a heat medium inlet. The opening 56b is connected to a heat medium discharge path 58 for discharging the heat medium 55 from the storage space 54, and functions as a heat medium outlet.

[0070] The heat medium 55 is introduced into the storage space 54 through the opening 56a. The heat medium 55 introduced into the storage space 54 exchanges heat with the membrane separation device 10 via the inner wall 52, and heats the membrane separation device 10. The heat medium 55 that has exchanged heat with the membrane separation device 10 is discharged from the storage space 54 through the opening 56b. In the heating unit 50, it is also possible to configure that the heat medium discharge path 58 is connected to the heat medium supply path 57, and the heat medium 55 circulates in the heat medium supply path 57, the storage space 54, and the heat medium discharge path 58.

[0071] The heat medium 55 is typically warm water. However, the heat medium 55 may also be steam (e.g., water vapor). The steam may be used at a pressure higher than the atmospheric pressure of the surrounding environment, or may be used at a pressure lower than the atmospheric pressure of the surrounding environment. In this specification, steam used at a pressure lower than the atmospheric pressure of the surrounding environment is sometimes referred to as vacuum steam. The temperature of the heat medium 55 is set so that the absolute value |T1-T2| becomes lower than 10°C. The temperature of the heat medium 55 may be the same as the temperature T1 of the fermentation liquid S supplied to the membrane separation device 10.

[0072] It should be noted that the heating unit 50 is not limited to Figure 2 The heating unit 50 may be a heater (particularly an electric heater) arranged so as to cover the membrane separation device 10 .

[0073] [Membrane separation device]

[0074] like Figure 3 As shown, the membrane separation device 10 includes a pervaporation membrane 11 and a tank 12. The tank 12 has a first chamber 13 and a second chamber 14. The first chamber 13 functions as a supply space to which the fermentation liquid S is supplied. The second chamber 14 functions as a permeation space to which the permeated fluid 80 is supplied. The permeated fluid 80 is obtained by the fermentation liquid S permeating the pervaporation membrane 11.

[0075] Pervaporation membrane 11 is disposed inside tank 12. Pervaporation membrane 11 partitions first chamber 13 and second chamber 14 inside tank 12. Pervaporation membrane 11 extends from one of a pair of wall surfaces of tank 12 to the other.

[0076] The first chamber 13 has a supply space inlet 13a and a supply space outlet 13b. The second chamber 14 has a permeation space outlet 14a. The supply space inlet 13a is an opening for supplying the fermentation liquid S to the supply space (first chamber 13). The permeation space outlet 14a is an opening for discharging the permeated fluid 80 from the permeation space (second chamber 14). The supply space outlet 13b is an opening for discharging the fermentation liquid S (non-permeated fluid 81) that has not permeated the permeation vaporization membrane 11 from the supply space (first chamber 13). The supply space inlet 13a, the supply space outlet 13b, and the permeation space outlet 14a are respectively formed on the wall surface of the tank 12, for example.

[0077] The membrane separation device 10 is suitable for a flow-through (continuous) membrane separation method. However, the membrane separation device 10 can also be used for a batch-type membrane separation method.

[0078] (Pervaporation membrane)

[0079] As described above, the pervaporation membrane 11 is typically a membrane (separation membrane) that preferentially permeates the organic compound C contained in the fermentation liquid S. The pervaporation membrane 11 generates a permeated fluid 80 containing the organic compound C as a gas by, for example, pervaporation.

[0080] like Figure 4 As shown, the pervaporation membrane 11 includes, for example, a separation functional layer 1 and a porous support 2 supporting the separation functional layer 1. The pervaporation membrane 11 may further include a protective layer (not shown) for protecting the separation functional layer 1. The separation functional layer 1 is, for example, directly in contact with the porous support 2. For example, the main surface 11a of the pervaporation membrane 11 on the separation functional layer side is exposed to the first chamber 13, and the main surface 11b of the porous support side is exposed to the second chamber 14.

[0081] (Separation Functional Layer)

[0082] Typically, the separation functional layer 1 is a layer that allows the organic compound C contained in the fermentation liquid S to preferentially pass through. The separation functional layer 1, for example, includes a hydrophobic material. In this specification, "hydrophobic material" refers to, for example, a material whose static contact angle of water exceeds 90° when a 10 μL drop of water (temperature 25° C.) is dropped on the surface of a test piece composed of the material. It should be noted that the static contact angle of water can be measured using a commercially available contact angle meter.

[0083] As a hydrophobic material, for example, compounds having a siloxane bond (Si-O-Si bond), olefin polymers, oils, fluorine compounds, etc. can be cited. The separation functional layer 1 preferably contains a compound having a siloxane bond as a hydrophobic material. The compound having a siloxane bond is typically an organosilicon polymer. The organosilicon polymer can be solid or liquid at 25°C. As a specific example of an organosilicon polymer, polydimethylsiloxane (PDMS) and the like can be cited. As a specific example of an olefin polymer, polyethylene, polypropylene, etc. can be cited. As an oil, for example, hydrocarbon oils such as liquid paraffin can be cited. As a fluorine compound, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), etc. can be cited. The hydrophobic material can be used alone or in combination of two or more.

[0084] The separation functional layer 1 may contain a hydrophobic material as a main component, or may be substantially composed of only a hydrophobic material. The "main component" refers to the component that is contained in the largest amount by weight in the separation functional layer 1 .

[0085] The separation function layer 1 may include: a matrix including a hydrophobic material, and fillers dispersed in the matrix. The fillers are embedded in the matrix. In the matrix, all fillers may be separated from each other or partially aggregated.

[0086] The filler includes, for example, inorganic materials such as zeolite, silica, and bentonite. The zeolite contained in the filler is preferably a high-silicon zeolite having a high ratio of silica to alumina. High-silicon zeolite is suitable for separating the fermentation liquid S due to its excellent hydrolysis resistance. As high-silicon zeolite, HSZ (registered trademark) manufactured by Tosoh Corporation, HiSiv (registered trademark) manufactured by United Showa Co., Ltd., USKY manufactured by United Showa Co., Ltd., and Zeoal (registered trademark) manufactured by Nakamura Superhard Co., Ltd. can be used.

[0087] The filler may include a metal-organic framework (MOF). The metal-organic framework is also called a porous coordination polymer (PCP). The metal-organic framework is preferably hydrophobic. The metal-organic framework includes, for example, metal ions and organic ligands. Examples of metal ions include Zn ions. Organic ligands include, for example, aromatic rings. Examples of aromatic rings contained in organic ligands include imidazole rings. Examples of organic ligands include 2-methylimidazole. Specific examples of metal-organic frameworks include ZIF-8.

[0088] The shape of the filler is, for example, particulate. In this specification, "particulate" includes spherical, ellipsoidal, scaly and fibrous. The average particle size of the filler is not particularly limited, for example, it is less than 50 μm, preferably less than 20 μm, and more preferably less than 10 μm. The lower limit of the average particle size of the filler is, for example, 0.01 μm. The average particle size of the filler can be determined, for example, by the following method. First, observe the cross section of the separation functional layer 1 with a transmission electron microscope. In the obtained electron microscope image, the area of ​​a specific filler is calculated by image processing. The diameter of a circle having the same area as the calculated area is regarded as the particle size (diameter of the particle) of the specific filler. The particle sizes of any number (at least 50) of fillers are calculated separately, and the average value of the calculated values ​​is regarded as the average particle size of the filler.

[0089] The content of the filler in the separation functional layer 1 is, for example, 10 wt% or more, preferably 30 wt% or more, and more preferably 40 wt% or more. The upper limit of the content of the filler in the separation functional layer 1 is not particularly limited, and is, for example, 70 wt%. The content of the matrix in the separation functional layer 1 is not particularly limited, and is, for example, 30 wt% to 90 wt%.

[0090] The thickness of the separation functional layer 1 is, for example, 200 μm or less, preferably 100 μm or less, and more preferably 80 μm or less. The thickness of the separation functional layer 1 may be 1.0 μm or more, 10 μm or more, or 30 μm or more.

[0091] The separation functional layer 1 may have a microporous structure with an average pore diameter of less than 0.01 μm, or may be a dense layer with no pores on the surface.

[0092] (Porous Support)

[0093] Examples of the porous support 2 include: nonwoven fabrics; porous polytetrafluoroethylene; aromatic polyamide fibers; porous metals; sintered metals; porous ceramics; porous polyesters; porous nylons; activated carbon fibers; latex; silicone; silicone rubber; a permeable (porous) polymer comprising at least one selected from polyvinyl fluoride, polyvinylidene fluoride, polyurethane, polypropylene, polyethylene, polystyrene, polycarbonate, polysulfone, polyetheretherketone, polyacrylonitrile, polyimide, and polyphenylene ether; a metal foam having open or closed cells; a polymer foam having open or closed cells; silicon dioxide; porous glass; a mesh, and the like. The porous support 2 may be a combination of two or more of these.

[0094] The porous support 2 has an average pore size of, for example, 0.01 to 0.4 μm. The thickness of the porous support 2 is not particularly limited, and is, for example, 10 μm or more, preferably 50 μm or more, and more preferably 100 μm or more. The thickness of the porous support 2 is, for example, 300 μm or less, and preferably 200 μm or less.

[0095] (Protective layer)

[0096] The protective layer, for example, covers the surface of the separation functional layer 1. The material of the protective layer is not particularly limited, and for example, a silicone resin can be cited. The material of the protective layer can also be the same as the material of the matrix of the separation functional layer 1. The thickness of the protective layer is not particularly limited, and for example, it is 0.5 μm or more, preferably 1 μm or more, more preferably 5 μm or more, and further preferably 10 μm or more. The thickness of the protective layer is, for example, 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less.

[0097] (Method for manufacturing pervaporation membrane)

[0098] The permeation vaporization membrane 11 can be made, for example, by forming a separation functional layer 1 on a porous support 2. In detail, first, a coating liquid containing a material for the separation functional layer 1 is prepared. The coating liquid may contain a filler and a dispersant for dispersing the filler in the coating liquid. In the case where the coating liquid contains a compound having a siloxane bond, the coating liquid may further contain a catalyst for curing the compound. Next, a coating film is obtained by applying the coating liquid on the porous support 2. The separation functional layer 1 is formed by drying the coating film.

[0099] [Operation of membrane separation system]

[0100] The operation method of the membrane separation system 100 (and the membrane separation device 10) includes, for example, a supply step of supplying the fermentation liquid S to the membrane separation device 10; and a membrane separation step of separating the fermentation liquid S into a permeated fluid 80 and a non-permeated fluid 81 through the permeation vaporization membrane 11. In the supply step, Figure 3 As shown, the fermentation liquid S is supplied to the first chamber 13 of the membrane separation device 10 through the supply space inlet 13a. Thus, the fermentation liquid S can be brought into contact with one surface (for example, the main surface 11a) of the pervaporation membrane 11.

[0101] As described above, the fermentation liquid S contains the volatile organic compound C and the microorganism that produces the organic compound C. The fermentation liquid S contains, for example, water in addition to the organic compound C and the microorganism. The fermentation liquid S is typically an aqueous solution containing the organic compound C and the microorganism.

[0102] The organic compound C contained in the fermentation liquid S is not particularly limited as long as it is volatile. In the present specification, the "volatile organic compound" refers to an organic compound having a boiling point of 20°C to 260°C, preferably 50°C to 260°C under atmospheric pressure (101.325 kPa). It should be noted that, when the concentration of the organic compound C in the aqueous solution is high, for example, an aqueous phase containing water as the main component and an organic phase having a higher content of the organic compound C than the aqueous phase are generated.

[0103] The number of carbon atoms in the organic compound C is not particularly limited, and may be, for example, 10 or less, 8 or less, 6 or less, or 4 or less. The lower limit of the number of carbon atoms in the organic compound C may be 1 or 2. The organic compound C may have a functional group containing an oxygen atom, such as a hydroxyl group, a carbonyl group, an ether group, or an ester group. In the organic compound C, the number of functional groups containing an oxygen atom is typically 1.

[0104] As the organic compound C, for example, alcohol, ketone, ester, etc. can be cited, preferably alcohol. In the case where the organic compound C is an alcohol, the organic compound C is easily miscible with water, and the environment in the system is not easy to deviate. The alcohol can be an alkyl alcohol consisting only of an alkyl group and a hydroxyl group, or an aryl alcohol containing an aryl group and a hydroxyl group. The alkyl alcohol can be any of a straight chain, a branched chain, and a ring. As the alkyl alcohol, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, isobutanol, tert-butanol, n-pentanol, etc. can be cited, preferably n-butanol. n-Butanol is a compound that generates two phases (aqueous phase and organic phase) in an aqueous solution when the content rate in the aqueous solution is about 8wt% or more. Therefore, in the case where the organic compound C is n-butanol, for example, by adjusting the content rate of the organic compound C in the permeated fluid to about 8wt% or more, an aqueous phase and an organic phase can be generated in the permeated fluid after liquefaction. In this case, by separating the aqueous phase and the organic phase, the permeated fluid can be easily purified. As the aryl alcohol, for example, phenol can be cited.

[0105] The ketone may be a dialkyl ketone consisting only of an alkyl group and a carbonyl group. Examples of the dialkyl ketone include methyl ethyl ketone (MEK) and acetone.

[0106] The ester may be a fatty acid alkyl ester consisting only of an alkyl group and an ester group. Examples of the fatty acid alkyl ester include ethyl acetate and the like.

[0107] It should be noted that the organic compound C is not limited to the above compounds and may be an aromatic hydrocarbon such as benzene, toluene, or xylene.

[0108] The fermentation liquid S may contain one organic compound C, or may contain two or more organic compounds C. The content of the organic compound C in the fermentation liquid S may be, for example, 50 wt% or less, 30 wt% or less, 10 wt% or less, 5 wt% or less, 2 wt% or less, or even 1 wt% or less. The lower limit of the content of the organic compound C is not particularly limited, and may be, for example, 0.01 wt%.

[0109] The organic compound C is a fermentation product produced by fermenting a carbon source by a microorganism, and is preferably an alcohol (bioalcohol) produced by the microorganism.

[0110] The fermentation liquid S may contain other components such as a carbon source, a nitrogen source, and inorganic ions in addition to water, an organic compound C, and microorganisms. Examples of the carbon source include polysaccharides such as starch and monosaccharides such as glucose.

[0111] The supply amount of the fermentation liquid S to the membrane separation device 10 is not particularly limited, and is determined according to the processing capacity of the membrane separation device 10 .

[0112] The fermentation liquid S supplied to the membrane separation device 10 may be preheated or not. The temperature T1 of the fermentation liquid S supplied to the membrane separation device 10 is, for example, above the temperature T3 of the fermentation liquid S in the tank 20. When the tank 20 is a fermentation tank, the temperature T3 is set to a temperature (fermentation temperature) that promotes the production of organic compounds C based on microorganisms. The temperature T3 is, for example, 15°C to 40°C, preferably 30°C to 40°C. The temperature T1 is, for example, lower than the temperature T4 at which the microorganisms in the fermentation liquid S die. That is, the temperatures T1, T3 and T4 satisfy the relationship of T4>T1≥T3, for example. The temperature T1 of the fermentation liquid S supplied to the membrane separation device 10 is, for example, 15°C to 75°C, may be 30°C to 75°C, or may be 30°C to 50°C.

[0113] The membrane separation process is carried out by the following method. First, in a state where the fermentation liquid S is in contact with one surface of the permeation vaporization membrane 11, the space adjacent to the other surface (for example, the main surface 11b) of the permeation vaporization membrane 11 is depressurized. In detail, the second chamber 14 is depressurized by passing through the space outlet 14a. The decompression in the second chamber 14 can be carried out, for example, by a decompression device 42. The pressure of the second chamber 14 is, for example, less than 50 kPa, and can also be less than 20 kPa, less than 10 kPa, less than 5 kPa, less than 3 kPa, and further less than 2 kPa. In addition, in this specification, unless otherwise specified, "pressure" refers to absolute pressure.

[0114] By reducing the pressure in the second chamber 14, a permeate fluid 80 having a high content of organic compound C can be obtained on the other side of the pervaporation membrane 11. In other words, the permeate fluid 80 is supplied to the second chamber 14. In the second chamber 14, the permeate fluid 80 is typically a gas. The permeate fluid 80 is discharged to the outside of the membrane separation device 10 through the permeation space outlet 14a.

[0115] On the other hand, the content of the organic compound C in the fermentation liquid S gradually decreases from the supply space inlet 13a toward the supply space outlet 13b of the first chamber 13. The fermentation liquid S (non-permeable fluid 81) treated in the first chamber 13 is discharged to the outside of the membrane separation device 10 through the supply space outlet 13b. The non-permeable fluid 81 is typically a liquid.

[0116] The pervaporation membrane 11 of the membrane separation device 10 can preferentially permeate the organic compound C contained in the fermentation liquid S. Therefore, the content of the organic compound C in the permeated fluid 80 obtained by the operation of the membrane separation device 10 is higher than that of the fermentation liquid S supplied to the membrane separation device 10. The ratio of the content (wt%) of the organic compound C in the permeated fluid 80 to the content (wt%) of the organic compound C in the fermentation liquid S is not particularly limited.

[0117] As described above, in the membrane separation step, the membrane separation system 100 adjusts the temperature of the membrane separation device 10 so that the absolute value (|T1-T2|) of the difference between the temperature T1 (°C) of the fermentation liquid S supplied to the membrane separation device 10 and the temperature T2 (°C) of the non-permeable fluid 81 discharged from the membrane separation device 10 becomes less than 10°C. In other words, the membrane separation step is performed so that a large temperature change does not occur in the fermentation liquid S (non-permeable fluid 81) treated by the pervaporation membrane 11. The temperature of the membrane separation device 10 can be adjusted by, for example, heating the membrane separation device 10 using the heating unit 50.

[0118] In the membrane separation step, when the absolute value |T1-T2| is lower than 10°C and the temperature change of the fermentation liquid S is suppressed, the reduction of microorganisms capable of generating fermented products in the fermentation liquid S can be suppressed. When the temperature T1 is about the fermentation temperature of the microorganisms, even if the fermentation liquid S (non-permeable fluid 81) whose temperature change is suppressed is supplied to the tank 20 as a fermentation tank, the temperature of the fermentation liquid S stored in the tank 20 hardly changes, and thus the reduction of the microorganisms in the fermentation liquid S can be suppressed. In this way, in the membrane separation system 100 of the present embodiment, the non-permeable fluid 81 that is sufficiently suitable for reuse can be obtained by the treatment (membrane separation step) using the pervaporation membrane 11. In the membrane separation system 100 of the present embodiment, for example, before the fermentation liquid S is supplied to the membrane separation device 10, it is not necessary to remove the microorganisms contained in the fermentation liquid S in advance, and it is not necessary to provide a pre-treatment device (for example, a filtration device) for removing the microorganisms in advance.

[0119] The absolute value |T1-T2| is preferably lower than 8°C, and may be lower than 5°C, lower than 3°C, or further lower than 2°C. The absolute value |T1-T2| may be substantially 0°C. The temperature T2 of the non-permeable fluid 81 discharged from the membrane separation device 10 may be higher than the temperature T1 of the fermentation liquid S supplied to the membrane separation device 10, or may be lower than the temperature T1. The temperature T2 is, for example, 15°C to 75°C, 30°C to 75°C, or 30°C to 50°C. The ratio T2 / T1 of the temperature T2 to the temperature T1 is not particularly limited.

[0120] The membrane separation process can be stopped by increasing the pressure of the permeation space in the membrane separation device 10. After stopping the membrane separation process, the pervaporation membrane 11 of the membrane separation device 10 can be cleaned by a known method. The pervaporation membrane 11 can be cleaned regularly or at any time.

[0121] According to the operation method of the present embodiment, for example, it is possible to produce the permeated fluid 80 having a high content of the organic compound C. In other words, according to the operation method of the present embodiment, it is possible to produce the organic compound C in the form of the permeated fluid 80 .

[0122] From another aspect of the present invention, the present invention provides a method for producing an organic compound C, comprising:

[0123] A supplying step of supplying a fermentation liquid S containing a volatile organic compound C and a microorganism that produces the organic compound C to a membrane separation device 10 having a pervaporation membrane 11;

[0124] A membrane separation step of separating the fermentation liquid S into a permeated fluid 80 and a non-permeated fluid 81 through a permeation vaporization membrane 11; and

[0125] a recovery step for recovering the permeated fluid 80;

[0126] The membrane separation step is performed in a state where the temperature of the membrane separation device 10 is adjusted so that the absolute value of the difference between the temperature T1 (° C.) of the fermentation liquid S supplied in the supply step and the temperature T2 (° C.) of the non-permeated fluid 81 discharged from the membrane separation device 10 becomes less than 10° C.,

[0127] The content rate of the organic compound C in the permeated fluid 80 is higher than the content rate of the organic compound C in the fermentation liquid S.

[0128] [Modification of membrane separation device]

[0129] The membrane separation device 10 may be a spiral membrane element, a hollow fiber membrane element, a coil-type membrane element in which a plurality of pervaporation membranes are stacked, a plate-and-frame membrane element, or the like. Figure 5 A spiral type membrane element is shown. Figure 5 The membrane separation device 15 includes a central tube 16 and a stack 17 . The stack 17 includes a pervaporation membrane 11 .

[0130] The central tube 16 has a cylindrical shape. A plurality of holes or slits are formed on the surface of the central tube 16 for allowing the permeating fluid 80 to flow into the interior of the central tube 16. Examples of the material of the central tube 16 include resins such as acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polyphenylene ether resin (PPE resin), and polysulfone resin (PSF resin); and metals such as stainless steel and titanium. The inner diameter of the central tube 16 is, for example, in the range of 20 to 100 mm.

[0131] The stack 17 includes a feed-side flow path material 18 and a permeate-side flow path material 19 in addition to the pervaporation membrane 11. The stack 17 is wound around the central tube 16. The membrane separation device 15 may further include an exterior material (not shown).

[0132] As the supply side flow path material 18 and the permeate side flow path material 19, for example, a net, woven fabric or knitted fabric made of a resin formed of polyethylene, polypropylene, polyethylene terephthalate (PET), polyphenylene sulfide (PPS) or ethylene-chlorotrifluoroethylene copolymer (ECTFE) can be used.

[0133] The membrane separation device 15 can be operated, for example, by the following method. First, the fermentation liquid S is supplied to one end of the wound stack 17. The internal space of the central tube 16 is depressurized. As a result, the permeated fluid 80 that permeates the pervaporation membrane 11 of the stack 17 moves to the inside of the central tube 16. The permeated fluid 80 passes through the central tube 16 and is discharged to the outside. The fermentation liquid S (non-permeated fluid 81) treated in the membrane separation device 15 is discharged to the outside from the other end of the wound stack 17.

[0134] [Modification of membrane separation system]

[0135] The membrane separation system 100 may include a plurality of membrane separation devices 10, and the plurality of membrane separation devices 10 may be connected in series or in parallel. In the present specification, the term "a plurality of membrane separation devices 10 are connected in series" means a configuration in which a plurality of membrane separation devices 10 are connected in series in such a manner that the fermentation liquid S (a non-permeable fluid during operation of the membrane separation system) discharged from the supply space of the front-stage membrane separation device 10 is supplied to the supply space of the rear-stage membrane separation device 10. The term "a plurality of membrane separation devices 10 are connected in parallel" means a configuration in which a plurality of membrane separation devices 10 are connected in parallel in such a manner that the fermentation liquid S sent from the tank 20 is supplied to the respective supply spaces of the plurality of membrane separation devices 10. The number of membrane separation devices 10 in the membrane separation system 100 is not particularly limited, and is, for example, 2 to 5.

[0136] Fig. 6A It is a schematic diagram of a membrane separation system 110 having two membrane separation devices 10A and 10B connected in series. The membrane separation system 110 has the same structure as the membrane separation system 100 except for the case where the membrane separation system 110 has two membrane separation devices 10A and 10B. Therefore, the same reference numerals are used for the common elements in the above-mentioned membrane separation system 100 and the membrane separation system 110 of the modified example, and their description is sometimes omitted. That is, the description of each embodiment can be applied to each other as long as it is not technically contradictory. Moreover, the various embodiments can also be combined with each other as long as it is not technically contradictory.

[0137] As described above, in the membrane separation system 110, the membrane separation devices 10A and 10B are connected in series. In detail, the membrane separation system 110 further includes a connection path 63 that connects the membrane separation devices 10A and 10B to each other. The connection path 63 is connected to the supply space outlet 13b of the membrane separation device 10A and the supply space inlet 13c of the membrane separation device 10B. It should be noted that the fermentation liquid supply path 60 is connected to the supply space inlet 13a of the membrane separation device 10A, and the non-permeable fluid discharge path 61 is connected to the supply space outlet 13d of the membrane separation device 10B.

[0138] The permeated fluid discharge path 62 includes a first portion 62a and a second portion 62b. The first portion 62a of the permeated fluid discharge path 62 is connected to the permeation space outlet 14a of the membrane separation device 10A, and the second portion 62b is connected to the permeation space outlet 14b of the membrane separation device 10B. The second portion 62b merges with the first portion 62a at a merging position 70.

[0139] For example, two pressure reducing devices 42A and 42B are arranged on the permeated fluid discharge path 62. The pressure reducing device 42A is located between the membrane separation device 10A and the confluence position 70, and can reduce the pressure in the permeation space of the membrane separation device 10A. The pressure reducing device 42B is located between the membrane separation device 10B and the confluence position 70, and can reduce the pressure in the permeation space of the membrane separation device 10B. However, one pressure reducing device may be arranged on the permeated fluid discharge path 62, and the pressure reducing device may be located between the confluence position 70 and the recovery unit 30. That is, one pressure reducing device may be shared by the membrane separation devices 10A and 10B.

[0140] The membrane separation system 110 includes a heating unit 50A for heating the membrane separation device 10A and a heating unit 50B for heating the membrane separation device 10B. The heating unit 50A is located near the membrane separation device 10A, for example, in direct contact with the membrane separation device 10A. The heating unit 50B is located near the membrane separation device 10B, for example, in direct contact with the membrane separation device 10B.

[0141] It should be noted that in the membrane separation system 110, the pervaporation membrane 11A of the membrane separation device 10A may be the same as or different from the pervaporation membrane 11B of the membrane separation device 10B except for the membrane area. The membrane area (m 2 ) relative to the total value of the membrane area of ​​the pervaporation membrane 11A and the membrane area of ​​the pervaporation membrane 11B (m 2 ) is not particularly limited.

[0142] The membrane separation system 110 can be operated by the following method. First, in the supply step, the pump 40 is operated to supply the fermentation liquid S from the tank 20 to the membrane separation device 10A, and further, the fermentation liquid S is supplied from the membrane separation device 10A to the membrane separation device 10B. In this way, the fermentation liquid S can be brought into contact with the pervaporation membrane 11A of the membrane separation device 10A and the pervaporation membrane 11B of the membrane separation device 10B.

[0143] Next, the permeation space of the membrane separation device 10A is depressurized through the permeation space outlet 14a, and the permeation space of the membrane separation device 10B is depressurized through the permeation space outlet 14b. Thus, the membrane separation process can be performed in both the membrane separation devices 10A and 10B, and permeated fluids can be obtained from the membrane separation devices 10A and 10B, respectively. It should be noted that the fermentation liquid S (non-permeated fluid) processed in the membrane separation device 10A is sent to the membrane separation device 10B through the connection path 63, and is further processed in the membrane separation device 10B.

[0144] In the membrane separation step, the membrane separation system 110 adjusts the temperature of the membrane separation device 10A so that the absolute value |T1A-T2A| of the difference between the temperature T1A (°C) of the fermentation liquid S supplied to the membrane separation device 10A and the temperature T2A (°C) of the non-permeated fluid discharged from the membrane separation device 10A becomes lower than 10°C. Similarly, the membrane separation system 110 adjusts the temperature of the membrane separation device 10B so that the absolute value |T1B-T2B| of the difference between the temperature T1B (°C) of the fermentation liquid S (non-permeated fluid discharged from the membrane separation device 10A) supplied to the membrane separation device 10B and the temperature T2B (°C) of the non-permeated fluid discharged from the membrane separation device 10B becomes lower than 10°C. The temperatures of the membrane separation devices 10A and 10B can be adjusted by heating by the heating units 50A and 50B, respectively.

[0145] Particularly preferably, the membrane separation system 110 adjusts the temperatures of the membrane separation devices 10A and 10B in the following manner, i.e., so that the absolute value |T1A-T2B| of the difference between the temperature T1A (°C) of the fermentation liquid S supplied to the membrane separation device 10A and the temperature T2B (°C) of the non-permeable fluid discharged from the membrane separation device 10B becomes lower than 10°C.

[0146] Next, in at least one of the membrane separation apparatuses 10A and 10B, the membrane separation step can be stopped by increasing the pressure in the permeation space.

[0147] Figure 6B1 is a schematic diagram of a membrane separation system 120 including two membrane separation apparatuses 10A and 10B connected in parallel to each other. The membrane separation system 120 has the same configuration as the membrane separation system 100 except that the membrane separation system 120 includes two membrane separation apparatuses 10A and 10B.

[0148] As described above, in the membrane separation system 120, the membrane separation devices 10A and 10B are connected in parallel with each other. Specifically, the fermentation liquid supply path 60 includes a first portion 60a and a second portion 60b. The first portion 60a of the fermentation liquid supply path 60 is connected to the supply space inlet 13a of the membrane separation device 10A, and the second portion 60b is connected to the supply space inlet 13c of the membrane separation device 10B. The second portion 60b branches from the first portion 60a at a branch position 71. The branch position 71 is located, for example, between the pump 40 and the membrane separation device 10A.

[0149] In addition, the non-permeated fluid discharge path 61 has a first portion 61a and a second portion 61b. The first portion 61a of the non-permeated fluid discharge path 61 is connected to the supply space outlet 13b of the membrane separation device 10A, and the second portion 61b is connected to the supply space outlet 13d of the membrane separation device 10B. The second portion 61b merges with the first portion 61a at a merging position 72. The merging position 72 is located, for example, between the pump 41 and the membrane separation device 10A.

[0150] Similar to the above-mentioned membrane separation system 110, the permeated fluid discharge path 62 has a first portion 62a and a second portion 62b. The first portion 62a of the permeated fluid discharge path 62 is connected to the permeation space outlet 14a of the membrane separation device 10A, and the second portion 62b is connected to the permeation space outlet 14b of the membrane separation device 10B. The second portion 62b merges with the first portion 62a at the merging position 70.

[0151] For example, two pressure reducing devices 42A and 42B are arranged on the permeated fluid discharge path 62. The pressure reducing device 42A is located between the membrane separation device 10A and the confluence position 70, and can reduce the pressure in the permeation space of the membrane separation device 10A. The pressure reducing device 42B is located between the membrane separation device 10B and the confluence position 70, and can reduce the pressure in the permeation space of the membrane separation device 10B. However, one pressure reducing device may be arranged on the permeated fluid discharge path 62, and the pressure reducing device may be located between the confluence position 70 and the recovery unit 30. That is, one pressure reducing device may be shared by the membrane separation devices 10A and 10B.

[0152] The membrane separation system 120 includes a heating unit 50A for heating the membrane separation device 10A and a heating unit 50B for heating the membrane separation device 10B. The heating unit 50A is located near the membrane separation device 10A, for example, in direct contact with the membrane separation device 10A. The heating unit 50B is located near the membrane separation device 10B, for example, in direct contact with the membrane separation device 10B.

[0153] It should be noted that in the membrane separation system 120, the pervaporation membrane 11A of the membrane separation device 10A may be the same as or different from the pervaporation membrane 11B of the membrane separation device 10B. The membrane area (m 2 ) relative to the total value of the membrane area of ​​the pervaporation membrane 11A and the membrane area of ​​the pervaporation membrane 11B (m 2 ) is not particularly limited.

[0154] The membrane separation system 120 can be operated by the following method. First, in the supply step, the pump 40 is operated to supply the fermentation liquid S from the tank 20 to the membrane separation devices 10A and 10B, respectively. Thus, the fermentation liquid S can be brought into contact with the pervaporation membrane 11A of the membrane separation device 10A and the pervaporation membrane 11B of the membrane separation device 10B, respectively.

[0155] Next, the permeation space of the membrane separation device 10A is depressurized through the permeation space outlet 14a, and the permeation space of the membrane separation device 10B is depressurized through the permeation space outlet 14b. Thus, the membrane separation process can be performed by both the membrane separation devices 10A and 10B, and permeated fluids can be obtained from each of the membrane separation devices 10A and 10B.

[0156] In the membrane separation step, the membrane separation system 120 adjusts the temperature of the membrane separation device 10A so that the absolute value |T1A-T2A| of the difference between the temperature T1A (°C) of the fermentation liquid S supplied to the membrane separation device 10A and the temperature T2A (°C) of the non-permeated fluid discharged from the membrane separation device 10A becomes lower than 10°C. Similarly, the membrane separation system 120 adjusts the temperature of the membrane separation device 10B so that the absolute value |T1B-T2B| of the difference between the temperature T1B (°C) of the fermentation liquid S supplied to the membrane separation device 10B and the temperature T2B (°C) of the non-permeated fluid discharged from the membrane separation device 10B becomes lower than 10°C. The temperatures of the membrane separation devices 10A and 10B can be adjusted by heating by the heating units 50A and 50B, respectively.

[0157] Next, in at least one of the membrane separation apparatuses 10A and 10B, the membrane separation step can be stopped by increasing the pressure in the permeation space.

[0158] <Implementation Method 2>

[0159] like Figure 7 As shown, the membrane separation system 130 of the second embodiment further includes a second membrane separation device 90, a heating unit 59, a second non-permeated fluid discharge path 64, and a second permeated fluid discharge path 65. Except for the above, the structure of the membrane separation system 130 is the same as that of the membrane separation system 100 of the first embodiment.

[0160] The second membrane separation device 90 includes a second permeation membrane 91 for separating the permeated fluid (first permeated fluid) discharged from the membrane separation device (first membrane separation device) 10 into a second permeated fluid and a second non-permeated fluid. Typically, the second permeation membrane 91 is a membrane that preferentially permeates the organic compound C contained in the fermentation liquid S. Therefore, the content of the organic compound C in the second permeated fluid separated by the second permeation membrane 91 is higher than that in the first permeated fluid. On the other hand, the content of the organic compound C in the second non-permeated fluid is lower than that in the first permeated fluid.

[0161] Second pervaporation membrane 91 may be the same as or different from pervaporation membrane (first pervaporation membrane) 11 included in first membrane separation device 10. The membrane area (m 2 ) relative to the total value of the membrane area of ​​the first pervaporation membrane 11 and the membrane area of ​​the second pervaporation membrane 91 (m 2 ) is not particularly limited.

[0162] The heating unit 59 can heat the second membrane separation device 90. The heating unit 59 is located near the second membrane separation device 90, for example, in direct contact with the second membrane separation device 90. As the heating unit 59, the heating unit described above for the heating unit 50 can be used.

[0163] The permeated fluid discharge path (first permeated fluid discharge path) 62 is connected to, for example, the supply space inlet 93a of the second membrane separation device 90, and is configured to transport the first permeated fluid from the first membrane separation device 10 to the second membrane separation device 90 during operation. A temperature sensor (not shown) for measuring the temperature T5 of the first permeated fluid supplied to the second membrane separation device 90 may be arranged on the first permeated fluid discharge path 62. The temperature sensor is located, for example, between the second membrane separation device 90 and the pressure reducing device 42, and is preferably located near the supply space inlet 93a of the second membrane separation device 90.

[0164] The second non-permeable fluid discharge path 64 is a path for discharging the second non-permeable fluid from the second membrane separation device 90 during operation, and is connected to the supply space outlet 93b of the second membrane separation device 90. The second non-permeable fluid discharge path 64 is provided with, for example, a pump 43 for controlling the flow rate of the second non-permeable fluid. A temperature sensor (not shown) for measuring the temperature T6 of the second non-permeable fluid discharged from the second membrane separation device 90 may also be provided on the second non-permeable fluid discharge path 64. The temperature sensor is, for example, located between the second membrane separation device 90 and the pump 43, and is preferably located near the supply space outlet 93b of the second membrane separation device 90.

[0165] The second non-permeable fluid discharge path 64 may be configured to be connected to the inlet 23 of the tank 20, and to deliver the second non-permeable fluid to the tank 20 during operation. That is, during operation, the second non-permeable fluid may be mixed with the fermentation liquid S in the tank 20. When the second non-permeable fluid is delivered to the tank 20, the fermentation liquid S and the second non-permeable fluid are mixed in the tank 20, and the content of the organic compound C in the fermentation liquid S is reduced. When the tank 20 is a fermentation tank, the reduction in the content of the organic compound C in the fermentation liquid S can suppress the stop of fermentation by microorganisms, thereby enabling continuous production of fermented products.

[0166] It should be noted that the second non-permeable fluid discharge path 64 may be connected to the non-permeable fluid discharge path (first non-permeable fluid discharge path) 61 instead of being connected to the inlet 23 of the tank 20. In this case, the first non-permeable fluid and the second non-permeable fluid are mixed at the confluence position of the first non-permeable fluid discharge path 61 and the second non-permeable fluid discharge path 64. The mixture of the first non-permeable fluid and the second non-permeable fluid is transported to the tank 20 through the first non-permeable fluid discharge path 61.

[0167] The second permeated fluid discharge path 65 is a path for discharging the second permeated fluid from the second membrane separation device 90 during operation, and is connected to the permeation space outlet 94a of the second membrane separation device 90. The second permeated fluid discharge path 65 may also be configured to be connected to the inlet 31 of the recovery unit 30, and to transport the second permeated fluid to the recovery unit 30 during operation.

[0168] For example, a pressure reducing device 44 is arranged on the second permeate fluid discharge path 65. The pressure reducing device 44 can reduce the pressure in the permeate space of the second membrane separation device 90. As the pressure reducing device 44, the device described above for the pressure reducing device 42 can be used. A heat exchanger for cooling the second permeate fluid can also be arranged on the second permeate fluid discharge path 65. The second permeate fluid of the gas can be condensed by the heat exchanger. The heat exchanger is, for example, a gas-liquid heat exchanger that generates heat exchange between a cooling medium such as an antifreeze liquid and a permeate fluid of the gas. The heat exchanger can be located between the second membrane separation device 90 and the pressure reducing device 44 (on the upstream side of the pressure reducing device 44), or between the pressure reducing device 44 and the recovery section 30 (on the downstream side of the pressure reducing device 44).

[0169] The membrane separation system 130 can be operated by the following method. First, the supply process and the membrane separation process are performed using the first membrane separation device 10. Thus, the first permeated fluid is discharged from the first membrane separation device 10. The first permeated fluid is supplied to the second membrane separation device 90 through the first permeated fluid discharge path 62 and contacts the second pervaporation membrane 91.

[0170] The first permeated fluid supplied to the second membrane separation device 90 is preferably in a liquid state. The liquid first permeated fluid can be obtained, for example, by condensing the gaseous first permeated fluid discharged from the first membrane separation device 10 using a heat exchanger. The first permeated fluid supplied to the second membrane separation device 90 may be preheated or may not be preheated. The temperature T5 of the first permeated fluid supplied to the second membrane separation device 90 is, for example, 15°C to 75°C, 30°C to 75°C, or 30°C to 50°C.

[0171] Next, the permeation space of the second membrane separation device 90 is depressurized through the permeation space outlet 94a, thereby performing a membrane separation process in the second membrane separation device 90. As a result, the first permeated fluid can be separated into a second permeated fluid and a second non-permeated fluid. As conditions for the membrane separation process in the second membrane separation device 90, the conditions for the membrane separation process in the first membrane separation device 10 described above can be cited.

[0172] In the membrane separation step, the membrane separation system 130 can adjust the temperature of the second membrane separation device 90 so that the absolute value (|T5-T6|) of the difference between the temperature T5 (°C) of the first permeated fluid supplied to the second membrane separation device 90 and the temperature T6 (°C) of the second non-permeated fluid discharged from the second membrane separation device 90 becomes less than 10°C. In other words, the membrane separation step can be performed in a manner that does not cause a large temperature change in the first permeated fluid (second non-permeated fluid) processed by the second pervaporation membrane 91. When the temperature T5 is about the fermentation temperature of microorganisms, even if the first permeated fluid (second non-permeated fluid) with suppressed temperature change is supplied to the tank 20 as a fermentation tank, the temperature of the fermentation liquid S stored in the tank 20 hardly changes, and thus the reduction of microorganisms in the fermentation liquid S can be suppressed.

[0173] The absolute value |T5-T6| is preferably lower than 8°C, and may be lower than 5°C, lower than 3°C, or further lower than 2°C. The absolute value |T5-T6| may be substantially 0°C. The temperature T6 of the second non-permeable fluid discharged from the second membrane separation device 90 may be higher than the temperature T5 of the first permeable fluid supplied to the second membrane separation device 90, or may be lower than the temperature T5. The temperature T6 is, for example, 15°C to 75°C, 30°C to 75°C, or 30°C to 50°C. The ratio T6 / T5 of the temperature T6 to the temperature T5 is not particularly limited.

[0174] Example

[0175] Hereinafter, the present invention will be described in more detail by way of measurement examples, but the present invention is not limited thereto.

[0176] [Fabrication of Pervaporation Membrane]

[0177] First, a permeation vaporization membrane is prepared by the following method. 1.650 kg (solid content concentration 30 wt%) of silicone resin (YSR3022 manufactured by Momentive Performance Materials Japan), 2.805 kg of toluene, 0.495 kg of high silica zeolite (HiSiv3000 manufactured by Showa Corporation), 0.0495 kg of silicone curing catalyst (YC6831 manufactured by Momentive Performance Materials Japan), and 0.0495 kg of acetylacetone as a curing retarder are mixed to prepare a coating liquid. Next, a coating film (thickness 500 μm) is obtained by coating the coating liquid on a porous support body (RS-50 manufactured by Nitto Denko Corporation) with a thickness of 150 μm. The coating film is heated at 90°C for 4 minutes to dry it, thereby preparing a separation functional layer with a thickness of 50 μm. In the separation functional layer, the weight ratio of silicone resin to high silica zeolite is 50:50. Thus, a permeation vaporization membrane is obtained.

[0178] [Fabrication of membrane separation device]

[0179] Using the manufactured pervaporation membrane, Figure 5 The spiral membrane element (membrane separation device) shown in FIG. 1 has an outer diameter of 4 inches (10.16 cm). The membrane area of ​​the pervaporation membrane in the membrane element is 6 m 2 .

[0180] (Measurement Example 1)

[0181] In use Figure 2 In the state where the heating unit shown heats the membrane separation device, the membrane separation device is subjected to the supply process and the membrane separation process. Specifically, first, a mixed liquid formed of isopropyl alcohol (IPA) and water is supplied to the supply space of the membrane separation device at a flow rate of 500 mL / min. The content of IPA in the mixed liquid is 5 wt%. The temperature T1 of the mixed liquid supplied to the membrane separation device is 43.6°C.

[0182] Next, the space (permeation space) inside the central tube of the membrane separation device is depressurized to 1.3 kPa, and the membrane separation process is performed. As a result, the mixed liquid is separated into permeation fluid and non-permeation fluid. As described above, the membrane separation process uses Figure 2 The heating unit shown in the figure is heated to the membrane separation device. 43.6°C warm water is introduced into the storage space of the heating unit as a heat medium. After the membrane separation process, the temperature T2 of the non-permeable fluid discharged from the membrane separation device is 42.0°C. The permeable fluid is obtained at a flow rate of 6 to 7 mL / min.

[0183] (Measurement Example 2)

[0184] Except that the membrane separation device was not heated, the supply step and the membrane separation step were performed on the membrane separation device in the same manner as in Measurement Example 1. As a result, the temperature T2 of the non-permeated fluid discharged from the membrane separation device was 32.2°C.

[0185] [Table 1]

[0186]

[0187] (*1) Temperature T1 of the mixed liquid supplied to the membrane separation device

[0188] (*2) Temperature T2 of the non-permeated fluid discharged from the membrane separation device

[0189] In Measurement Example 1 in which the membrane separation device was heated, the absolute value |T1-T2| of the difference between temperature T1 and temperature T2 was less than 10° C., whereas in Measurement Example 2 in which the membrane separation device was not heated, the absolute value |T1-T2| was greater than 10° C. When the membrane separation device was operated under the conditions of Measurement Example 1 using fermentation liquid as the feed liquid, the reduction of microorganisms capable of producing fermented products in the fermentation liquid (non-permeable fluid) treated by the pervaporation membrane was suppressed, and it was estimated that it was sufficiently suitable for reuse.

[0190] Industrial Applicability

[0191] In the membrane separation system of the present embodiment, a non-permeated fluid that is sufficiently suitable for reuse can be obtained by treatment using a pervaporation membrane.

Claims

1. A membrane separation system comprising a membrane separation device, wherein: The membrane separation device comprises a pervaporation membrane, The pervaporation membrane separates a fermentation liquid containing volatile organic compounds and microorganisms producing the organic compounds into a permeated fluid and a non-permeated fluid. The membrane separation system adjusts the temperature of the membrane separation device so that the absolute value of the difference between the temperature T1 (°C) of the fermentation liquid supplied to the membrane separation device and the temperature T2 (°C) of the non-permeated fluid discharged from the membrane separation device becomes less than 10°C. 2 . The membrane separation system according to claim 1 , wherein the temperature of the membrane separation device is adjusted so that the absolute value becomes lower than 3° C.

3. The membrane separation system according to claim 1, wherein: The temperature T1 is 30°C to 75°C. 4 . The membrane separation system according to claim 1 , further comprising a heating unit for heating the membrane separation device.

5. The membrane separation system according to claim 1, wherein: The content rate of the organic compound in the permeated fluid is higher than the content rate of the organic compound in the fermentation liquid.

6. The membrane separation system according to claim 1, wherein: The organic compound is an alcohol. 7 . The membrane separation system according to claim 1 , further comprising a tank for storing the fermentation liquid to be supplied to the membrane separation device.

8. The membrane separation system according to claim 7, further comprising a non-permeated fluid discharge path connected to the membrane separation device and used to discharge the non-permeated fluid from the membrane separation device. The non-permeated fluid discharge path is connected to the tank. 9 . The membrane separation system according to claim 1 , further comprising a second membrane separation device having a second pervaporation membrane for separating the permeated fluid into a second permeated fluid and a second non-permeated fluid.

10. The membrane separation system according to claim 9, wherein: The temperature of the second non-permeated fluid discharged from the second membrane separation device is 30°C to 75°C.

11. The membrane separation system according to claim 9, further comprising: a tank for storing the fermentation liquid to be supplied to the membrane separation device; and a second non-permeated fluid discharge path connected to the second membrane separation device and used to discharge the second non-permeated fluid from the second membrane separation device, The second non-permeated fluid discharge path is connected to the tank.

12. A method for operating a membrane separation device, which is a method for operating a membrane separation device having a pervaporation membrane, the method comprising: a supplying step of supplying a fermentation liquid containing a volatile organic compound and a microorganism producing the organic compound to the membrane separation device; and a membrane separation step of separating the fermentation liquid into a permeable fluid and a non-permeable fluid by using the pervaporation membrane; The membrane separation step is performed while the temperature of the membrane separation device is adjusted so that the absolute value of the difference between the temperature T1 (°C) of the fermentation liquid supplied in the supply step and the temperature T2 (°C) of the non-permeable fluid discharged from the membrane separation device becomes lower than 10°C.

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