JP2008099667A - Method and apparatus for producing alcohol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for producing alcohol by which a reduction in permeability caused by a fouling material is restored in a method for producing alcohol by continuous filtration concentration of sugar fermented liquid using a separating membrane. <P>SOLUTION: The method for producing alcohol by filtration concentration of the alcohol containing fermentation liquid obtained by fermentation of sugar, using a separating membrane having a temperature sensitive polymer on the surface layer for the filtration concentration, wherein the filtration concentration is carried out by repeating the filtration concentration and cleaning of the separating membrane, and the temperature in the filtration concentration is set higher than the temperature of the lower critical solution temperature of the temperature sensitive polymer and the temperature of the separating membrane when being cleaning is set lower than the critical solution temperature of the temperature sensitive polymer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing fermented alcohol, in which an alcohol-containing fermentation broth is filtered and concentrated using a separation membrane having a temperature-sensitive polymer on the surface layer.

  The end of the 20th century, when mass consumption and mass disposal are over, and in the 21st century, where the creation of an environmentally harmonious society is required, it is expected to promote the utilization of biomass resources, which are recyclable resources.

  Examples of energy resources obtained from biomass resources include methane gas, hydrogen gas, and alcohol (ethanol, butanol). Among them, ethanol obtained by alcoholic fermentation with yeast can be used by mixing with gasoline, and thus has been put to practical use as ethanol-mixed gasoline in the United States and Brazil. However, the ethanol concentration in the fermentation broth obtained by the fermentation method is about a dozen or so%, and in order to obtain a concentration that can be used as energy, it is necessary to dehydrate by a concentration step. A distillation method is generally used for the concentration step, but the distillation step requires high energy that is said to consume about half the energy of ethanol produced. Furthermore, before the distillation step, a solid-liquid separation step for removing yeast from the fermentation broth is also necessary, and the distillation concentration step of the fermentation broth is inferior in energy efficiency and work efficiency.

  In addition, since butanol obtained by the fermentation method exhibits strong cytotoxicity, butanol concentration in the fermentation solution can be increased only to about 2%, which is much less efficient than ethanol. Furthermore, since butanol fermentation has a complicated metabolic pathway that produces acetic acid and butyric acid during the acid production phase and acetone, butanol, and ethanol during the solvent production phase, it is difficult to control the fermentation. In order to improve the above problems, an extraction fermentation method is being studied in which an extractant is added to the fermenter and fermentation is performed while extracting butanol produced, and the inhibition by butanol is suppressed. May be a fermentation inhibitor.

  Furthermore, since butanol has a higher boiling point than water, it is necessary to distill off a large amount of water in ordinary distillation, and a method for efficiently concentrating the water is required.

  In order to overcome such a problem of inefficiency, a fermentation alcohol concentration method using a separation membrane has been devised as an alternative to the distillation method. Patent Document 1 discloses a method of concentrating alcohol by a pervaporation separation method using a silicon rubber membrane. However, this method is so-called batch filtration concentration in which the produced fermentation liquor is taken out from the fermenter and then processed under specific conditions in the pervaporation device, and is not rational in terms of the device configuration.

As for a continuous alcohol concentration method instead of a batch method, for example, Patent Document 2 discloses a method using a silicalite film coated with silicon rubber. When the silicalite membrane is introduced into the fermenter and the concentration operation is performed, fouling due to organic acids such as succinic acid and malic acid that are by-produced in the fermenter occurs over time. This fouling is suppressed by coating the surface of the silicalite film with silicon rubber to make the film surface hydrophobic. However, since fouling substances accumulate on the silicon rubber surface over time, the performance of the separation membrane may deteriorate over time.
JP 57-136905 A JP 2003-135090 A

  In view of the above-described problems of the prior art, the present invention reduces the permeation performance of a separation membrane by a fouling substance in a method of producing alcohol by filtration and concentration of a sugar fermentation solution using a separation membrane performed continuously. An object of the present invention is to provide a manufacturing method and a manufacturing apparatus that are easy to recover.

The present invention for solving the above problems is achieved by the following configurations (1) to (4).
(1) In a method for producing alcohol by filtering and concentrating an alcohol-containing fermentation broth obtained by fermenting sugar with a separation membrane, using a separation membrane having a thermosensitive polymer on the surface layer, filtration concentration and washing of the separation membrane; The filtration concentration is repeated until the temperature during filtration concentration is equal to or higher than the lower critical solution temperature of the thermosensitive polymer, and the temperature during washing of the separation membrane is lower than the lower critical solution temperature of the thermosensitive polymer. A method for producing alcohol.
(2) The method for producing alcohol according to (1) above, wherein the separation membrane is washed by backwashing.
(3) The method for producing alcohol according to (1) or (2) above, wherein the obtained filtrate is filtered and concentrated with a filtration device provided with a separation membrane having a thermosensitive polymer as a surface layer.
(4) The alcohol production method according to any one of (1) to (3), wherein the alcohol is butanol.
(5) An alcohol production apparatus comprising a fermenter for sugar fermentation and a membrane filtration device for filtering and concentrating the fermentation liquor produced in the fermenter, the membrane filtration device comprising a thermosensitive polymer And a device for adjusting the temperature of the separation membrane and / or a device for heating the fermentation broth sent to the separation membrane and / or a device for cooling the backwashing solution. An alcohol production apparatus.
(6) The alcohol production apparatus according to (5), wherein a membrane filtration device provided with a separation membrane having a temperature-sensitive polymer as a surface layer is immersed in the fermentation tank.
(7) A membrane filtration device provided with a separation membrane having a thermosensitive polymer on its surface layer is immersed in the fermenter, and a filtration device further comprising a separation membrane having a thermosensitive polymer on its surface layer is a fermenter The alcohol production apparatus according to (5) or (6), which is installed outside.

  According to the method and apparatus of the present invention, the problems in the production of sugar fermentation alcohol are eliminated by performing sugar fermentation and filtration concentration in a continuous manner, and the permeation performance deterioration of the separation membrane by the fouling substance is recovered. It becomes easy, and it becomes possible to concentrate alcohol continuously for a long period of time.

  That is, in the method of the present invention, a separation membrane having a temperature-sensitive polymer as a surface layer is used, and the temperature at the time of filtration and concentration and the temperature at the time of washing are respectively equal to or higher than the lower critical solution temperature and the lower critical solution temperature. Therefore, the surface of the separation membrane exhibits hydrophobicity during filtration and concentration, and alcohol can be preferentially filtered over water. On the other hand, the surface of the separation membrane exhibits hydrophilicity during washing, and further swells to increase the effective volume, so that the fouling substance adsorbed by the hydrophobic interaction is easily desorbed. Therefore, according to the present invention, the alcohol can be concentrated continuously for a long period of time.

  As the raw material for the sugar fermentation alcohol in the method of the present invention, glucose, maltose, sucrose sugar monosaccharides, disaccharides and polysaccharides are used. Such a monosaccharide, disaccharide, or polysaccharide-containing substance may be hydrolyzed and used as a raw material. For example, cellulose or starch may be hydrolyzed and used. In the sugar fermentation reaction, an aqueous solution containing about 10 to 30% by weight of the aforementioned saccharide is used as the medium. Furthermore, yeast extract, magnesium salt, vitamins, amino acids and the like are added to the medium for the purpose of promoting yeast growth.

  The present invention is characterized in that alcohol fermentation in a fermenter and filtration and concentration with a separation membrane of alcohol produced by fermentation are continuously performed. In addition to the medium described above, yeast and bacteria that ferment sugar and convert it to alcohol are added to the fermenter. During filtration and concentration using a separation membrane, yeast and bacteria are not substantially filtered and remain in the fermenter. For this reason, although the yeast density | concentration and bacteria density | concentration in a fermenter rise, since the sugar density | concentration used as a nutrient source will fall when yeast density | concentration and bacterial density | concentration rise, it will approach a certain equilibrium density | concentration.

  As yeast or bacteria used for fermentation in the present invention, any yeast or bacteria can be used as long as they produce alcohol. It is particularly preferable to use yeast or bacteria having the same because the fermentation reaction and filtration and concentration using a separation membrane can be carried out in a single tank.

  The separation membrane used for filtration concentration in the present invention is a membrane having a temperature-sensitive polymer on the surface layer and having a filtration separation function, and the temperature-sensitive polymer is a surface layer located on the treated solution side of both surface layers of the separation membrane. It only has to exist. A thermosensitive polymer is a polymer whose properties can be reversibly changed to hydrophilicity or hydrophobicity due to changes in temperature. In addition to changes in properties due to temperature, volume changes due to shrinkage or swelling of the polymer are also observed. The The temperature showing this hydrophilic / hydrophobic boundary is called the lower critical solution temperature. The temperature-sensitive polymer becomes a hydrophobic, water-insoluble solid polymer above the lower critical solution temperature, and becomes a hydrophilic and water-soluble polymer below the lower critical solution temperature.

  Examples of such a temperature-sensitive polymer include the following acrylic acid derivatives. For example, homopolymers such as ethyl acrylamide, N, N-dimethylaminoethyl methacrylate, N-isopropyl acrylamide, acryloyl-L-proline methyl ester, N-3-ethoxypropyl acrylamide, the above monomers and / or methacrylic acid , Butyl methacrylate, 2-carboxyisopropylacrylamide, acrylic acid, acrylamide, N, N-dimethylaminoethyl methacrylate, ethylacrylamide, N, N-diethylacrylamide, and a copolymer with ethylene glycol dimethacrylate. By appropriately combining the above monomers, a thermosensitive polymer having a desired lower critical solution temperature can be prepared. Among them, polyethylacrylamide (lower critical solution temperature: 80 ° C.), poly N, N-dimethylaminoethyl methacrylate (lower critical solution temperature: 50 ° C.), and poly N-isopropylacrylamide (lower critical solution temperature: 37 ° C.) are used. It is preferably used because it is easily available.

  The separation membrane used for filtration concentration in the present invention may be prepared by a known technique except that the surface layer has a temperature-sensitive polymer as described above. For example, a well-known porous or non-porous membrane may be used inside, and a separation membrane treated so that a thermosensitive polymer is present on the surface layer may be used. Examples of porous or non-porous separation membranes include polyolefin membranes, silicon rubber membranes, polytrimethylsilylpropyne membranes, polyimide membranes, silicalite membranes, fluororesin membranes, polyacrylonitrile membranes, polysulfone membranes, polyethersulfone membranes. And cellulose acetate membrane. When composed of a hydrophobic material with a higher affinity for alcohol than water, the alcohol can be filtered and concentrated efficiently, so polyolefin film, silicon rubber film, polytrimethylsilylpropyne film, polyimide film, silicalite film, fluororesin A system film is particularly preferably used.

  In order for the thermosensitive polymer to be present on the surface layer of the separation membrane, a conventional method can be employed. For example, a method of impregnating the above-described separation membrane with the temperature-sensitive polymer solution from the surface thereof or a method of gelling inside the pores of the separation membrane to insolubilize can be employed. Furthermore, a method of immobilizing on the surface layer of the separation membrane by radiation grafting using an electron beam or the like can be employed. In the case of radiation grafting, the amount of the temperature-sensitive polymer to be introduced can be controlled by adjusting the polymerization conditions such as the electron dose.

  In the present invention, the selection of the specific polymer type used as the thermosensitive polymer, the temperature conditions when filtering using the separation membrane having the thermosensitive polymer on the surface layer, etc. are the heat resistance of yeast and bacteria used in the fermenter. Considering the overall efficiency of the equipment, fermentation conditions, filtration concentration conditions, etc., the temperature during filtration concentration, i.e., the temperature of the fermentation liquid and the separation membrane temperature during filtration, is the temperature-sensitive polymer surface of the separation membrane. What is necessary is just to select suitably so that it may become more than a lower critical solution temperature.

  For example, when yeast and bacteria are not heat resistant and can only be fermented at about 30 ° C, the fermentation broth is taken out from the fermenter and guided with a pipe, and the pipe is heated to make the fermentation broth the lower criticality of the thermosensitive polymer. After reaching the melting temperature or higher, it may be brought into contact with the separation membrane of the membrane filtration device, and yeast and bacteria may be sequentially added to the fermenter in order to compensate for dead or inactivated yeast and bacteria. In this case, it is necessary to conduct experiments while varying the heating conditions using various separation membranes with different lower critical melting temperatures of the temperature-sensitive polymer on the surface of the separation membrane and determine the optimum conditions that minimize the total cost. Good.

  On the other hand, when yeast and bacteria have heat resistance and can be fermented even at 40 ° C or higher, poly N-isopropylacrylamide having a lower critical solution temperature of 37 ° C is used in a single fermenter kept at 40 ° C or higher. Fermentation and filtration concentration can be performed. In this case, the temperature in the fermenter does not exceed the allowable upper limit temperature of the heat resistance of the yeast or bacteria, and the heat resistance of the yeast or bacteria is not less than the lower critical solution temperature of the thermosensitive polymer used on the surface of the separation membrane. Although it is necessary to use a temperature-sensitive polymer having a lower critical solution temperature lower than the allowable upper limit temperature, it is possible to reduce the cost of equipment and power as a whole.

  As described above, since the temperature-sensitive polymer is hydrophobic at a temperature lower than the lower critical solution temperature, it has higher affinity for alcohol than water, and preferentially permeates alcohol, so the alcohol-containing fermentation broth is filtered and concentrated. Sometimes it is necessary that the temperature of the fermentation liquor or separation membrane be equal to or higher than the lower critical solution temperature of the thermosensitive polymer.

  When fermentation and filtration concentration are carried out continuously, the surface of the separation membrane fouls due to yeast, bacteria, and fermentation by-products contained in the fermentation liquid, and the separation performance and permeation performance gradually decrease. Therefore, it is necessary to remove the fouling substance and recover the separation performance and permeation performance, that is, to clean the membrane surface at appropriate intervals. When the separation membrane having a temperature-sensitive polymer in the surface layer used in the present invention is lower than the lower critical solution temperature, the temperature-sensitive polymer exhibits hydrophilicity and further expands to increase the effective volume. For this reason, when the separation membrane or the separation membrane surface layer is cooled below the lower critical solution temperature during washing, the properties of the separation membrane surface layer can be changed from hydrophobic to hydrophilic. Adsorption of fouling substances on the surface of the separation membrane is thought to be dominated by hydrophobic interaction other than physical adsorption, so the properties of the surface of the separation membrane change from hydrophobic to hydrophilic by cooling. Then, the hydrophobic interaction between the fouling substance and the separation membrane surface layer is lowered, and the fouling substance is easily detached from the membrane surface. Further, since the temperature-sensitive polymer expands due to cooling and the effective volume increases, the effect of reducing the aggregation / fixation of the fouling substances and the effect of dispersing the fouling substances can reduce the fouling substance from the film surface. Desorption is promoted.

  If the separation membrane is a porous membrane, it is preferable to perform back-flow cleaning in addition to cooling to less than the above-mentioned lower critical solution temperature when cleaning the membrane, since the cleaning effect is enhanced. In this case, it is preferable that the backwashing solution is cooled in advance and adjusted so as to be lower than the lower critical solution temperature when reaching the surface of the separation membrane. As the backwash solution, an alcohol aqueous solution, a culture medium, or a diluted solution of the culture medium that is a permeate may be used, but water is particularly preferable in consideration of ease of handling. The conditions for backflow cleaning may be set so that the total cost is minimized by comprehensively considering the cleaning efficiency and the recovery rate. For example, in the case of constant flow rate filtration, it is preferable to employ conditions for backwashing for several minutes at a flow rate twice the filtration flow rate.

  An apparatus for carrying out the method of the present invention is an alcohol production apparatus comprising a fermenter for sugar fermentation and a membrane filtration device for filtering and concentrating the fermentation liquor produced in the fermenter, The filtration device is provided with a separation membrane having a temperature-sensitive polymer as a surface layer, an apparatus for adjusting the temperature of the separation membrane, an apparatus for heating the fermentation broth sent to the separation membrane, and a backwashing solution. A manufacturing apparatus provided with at least one or more temperature control devices among the devices to be cooled can be exemplified. What is necessary is just to install the temperature control apparatus with which this apparatus is provided so that the temperature conditions of above-mentioned this invention method can be achieved.

  In this production apparatus, an alcohol-containing fermented liquid obtained by fermenting sugar in a fermenter is filtered and concentrated by a membrane filtration apparatus having a separation membrane having a thermosensitive polymer on the surface layer, and a permeate with an increased alcohol concentration. Can be obtained. As the driving force for concentration by filtration, a pressurizing means on the stock solution side or a suction means on the permeate side may be provided. As the pressurizing means, a pump may be used, or a pressure due to a water level difference may be used. Moreover, what is necessary is just to utilize a pump and a siphon as a suction means. Further, the temperature difference can be used as the driving force by setting the stock solution side to a high temperature and the permeate side to a low temperature.

  At the time of filtration concentration, an apparatus for adjusting the temperature of the separation membrane and / or a fermentation broth to be sent to the separation membrane is added so that the temperature of the separation membrane and the temperature of the fermentation liquid are equal to or higher than the lower critical solution temperature of the thermosensitive polymer. What is necessary is just to operate the apparatus to heat as needed. By performing filtration and concentration under this temperature condition, the separation membrane becomes hydrophobic and alcohol can be preferentially permeated. On the other hand, when cleaning the separation membrane, a device for adjusting the temperature of the separation membrane and / or a device for cooling the backflow cleaning solution may be operated as necessary. By performing membrane cleaning under this temperature condition, the temperature-sensitive polymer on the surface of the separation membrane becomes hydrophilic, facilitating the falling off of the fouling substance adsorbed by hydrophobic interaction, and improving the cleaning efficiency. it can.

  In particular, in the case of butanol, where it is difficult to increase the concentration in the fermentation broth due to its strong cytotoxicity, the above-mentioned production method and production apparatus can be used to reduce the cytotoxicity by extracting the produced butanol from the fermenter. And the fermentation can be continued.

  In addition, the alcohol-containing fermentation broth was filtered and concentrated with a membrane filtration device equipped with a separation membrane having a temperature-sensitive polymer on the surface, and the resulting filtrate was further equipped with a separation membrane having a temperature-sensitive polymer on the surface. Examples of the production method include filtration and concentration with a filtration device. In particular, in the case of butanol, which has a boiling point higher than that of water and lower distillation purification efficiency, the purification efficiency is increased by concentrating with a membrane filtration apparatus equipped with a separation membrane having a surface-sensitive polymer in the second and subsequent stages. be able to. In addition, the devices in the second and subsequent stages have less fouling due to yeast, bacteria, and fermentation by-products than the devices in the first stage, and can suppress the cleaning frequency of the separation membrane.

  As an apparatus for carrying out such a production method, a membrane filtration apparatus equipped with a separation membrane having a temperature-sensitive polymer on the surface layer is immersed in the fermenter, and further has a temperature-sensitive polymer on the surface layer. A production apparatus in which at least one filtration apparatus provided with a separation membrane is installed outside the fermenter can be exemplified. Fermentation can be continued while extracting the alcohol as a product with the membrane filtration device immersed in the fermenter, and the concentration of the alcohol extracted with the membrane filter installed outside the fermenter can be increased. In addition, the membrane filtration apparatus installed outside the fermenter may use a plurality of membrane filtration apparatuses as necessary, and may use them in combination in series and / or in parallel.

  The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

  A separation membrane having a temperature-sensitive polymer on the surface layer used for filtration and concentration of sugar fermentation alcohol is prepared by first producing a fluororesin-based hollow fiber membrane by the usual method described below, and a temperature-sensitive polymer (poly N--) on the outer surface layer. (Isopropylacrylamide) was produced by radiation grafting.

  The fluororesin-based hollow fiber membrane was produced by the following procedure. First, a polymer solution composed of 35% by weight of polyvinylidene fluoride (KYNAR760 manufactured by Arkema Co., Ltd.) and 65% by weight of dimethyl sulfoxide was discharged from an annular hollow fiber spinning base while injecting an aqueous solution of 80% by weight of dimethyl sulfoxide into the hollow part. After solidifying in a 30 ° C. water bath, the membrane was washed with pure water to produce a water-containing hollow fiber membrane.

  Next, this hollow fiber membrane was immersed in methanol for 24 hours and then dried at room temperature. Cut the dried hollow fiber membrane into a length of 40 cm, bundling 20 pieces, potting both ends with an epoxy adhesive, cutting after curing to produce an opening in the bundle of hollow fiber membranes, both ends made of epoxy resin A potted polyvinylidene fluoride hollow fiber membrane bundle was prepared.

  Finally, the obtained polyvinylidene fluoride hollow fiber membrane bundle was immersed in an isopropyl alcohol solution containing 30% by weight of poly N-isopropylacrylamide for 30 minutes so that the isopropyl alcohol solution did not enter the hollow portion. A bundle of polyvinylidene fluoride hollow fiber membranes coated with poly N-isopropylacrylamide on the outer surface in this way was irradiated with gamma rays under the condition of a gamma ray absorbed dose of 28 kGy and subjected to radiation grafting. The obtained bundle of polyvinylidene fluoride hollow fiber membranes having poly-N-isopropylacrylamide as a surface layer was immersed in isopropyl alcohol for 1 hour and then in methanol for 24 hours, and then dried at room temperature.

  The obtained poly (N-isopropylacrylamide) -coated polyvinylidene fluoride hollow fiber membrane bundle was sealed in a case equipped with an inlet nozzle and an outlet nozzle for a low temperature solution prepared with an acrylic pipe, and potted at the end of the case. A membrane module was produced. For use in a comparative example, a polyvinylidene fluoride hollow fiber membrane bundle (no thermosensitive polymer was attached) was similarly enclosed in a case and potted at the end of the case to produce a membrane module.

  Moreover, the manufacture of the ethanol-containing fermentation broth by fermentation was performed by the following method. A medium containing 20% by weight glucose aqueous solution and yeast extract as fermentation raw materials and baker's yeast (Saccharomyces cerevisiae, manufactured by Oriental Yeast Co., Ltd.) were added to the fermenter and fermented at 30 ° C. for 7 days. During this time, the glucose concentration was traced with a differential refractometer, and a medium was appropriately added so as to be 10 ± 2% by weight.

  Production of butanol-containing fermentation broth by fermentation was performed by the following method. To the fermenter, a medium containing 5% by weight glucose aqueous solution and yeast extract as fermentation raw materials, and Clostridium acetobutylicum (American Type Culture Collection 824), a bacterium for causing fermentation, are added and fermented at 30 ° C. for 7 days. It was. During this time, the glucose concentration was traced with a differential refractometer, and a medium was appropriately added so as to be 5 ± 2% by weight.

  And the filtration concentration by the separation membrane of ethanol or butanol was performed using the apparatus typically shown in FIG. That is, while performing the fermentation reaction as described above in the fermenter 1, the produced ethanol or butanol-containing fermentation broth is fed with the pump 2 and heated to 45 ° C. with the heater 3 in the middle of the feeding, and the separation membrane module 4 was supplied from the supply port 4A and concentrated by filtration. The permeate, which was filtered and concentrated to increase the alcohol concentration, exited from the permeate outlet 4D and was taken out to the storage tank 5. The remaining fermentation liquid other than the permeate was taken out from the outlet 4 </ b> B and returned to the fermenter 1. That is, the fermentation broth as the stock solution was circulated outside the hollow fiber membrane.

  After 7 days of fermentation and filtration concentration, washing was performed for 3 minutes. Washing was performed by two methods. In the washing method 1, the liquid feeding by the pump 2 is stopped, and then the low-temperature permeate is fed from the storage tank 5 by the pump 6 into the hollow fiber membrane on the permeate side, and flows from the permeate inlet 4C. The permeate discharged from the permeate outlet 4D was caused to flow into the storage tank 5, whereby the low temperature solution was fed and circulated, and the separation membrane was cooled from the permeate side. Here, the temperature of the low-temperature permeate side solution was controlled to be 18 ° C. at the permeate inlet 4C.

  Washing method 2 involves backwashing and was performed according to the following method. First, as with the washing method 1, the pump 2 stops feeding, and then the low-temperature permeate is fed from the storage tank 5 by the pump 6 into the hollow fiber membrane on the permeate side, and flows from the permeate inlet 4C. It was. Unlike the cleaning method 1, the valve 7 was closed, and the permeate was passed through the hollow fiber membrane wall from the permeate side to the stock solution side and taken out from the supply port 4A and the outlet 4B to the outside of the module.

  The following experiments of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 were all performed in parallel using the same fermentor. This is to equalize the degree of load on the separation membrane due to the nature of the stock solution and the environment.

<Example 1>
Filtration concentration and washing were performed using a membrane module in which a bundle of polyvinylidene fluoride hollow fiber membranes coated with poly N-isopropylacrylamide was used as a separation membrane. Washing was performed according to the procedure of Washing Method 1.

The permeation rate of ethanol after 1 hour of filtration concentration was 0.24 kgm ⁻² h ⁻¹ and the permeation rate of water was 0.32 kgm ⁻² h ⁻¹ . The ethanol permeation rate after filtration concentration 7 days was 0.05 kgm ⁻² h ⁻¹ and the water permeation rate was 0.11 kgm ⁻² h ⁻¹ .

And the permeation | transmission rate of ethanol after the washing | cleaning by the washing | cleaning method 1 was 0.20kgm ^<-2 > h- ¹ , and the permeation | transmission rate of water was 0.28kgm ^- 2h ^{- 1} . The ethanol permeation rate was recovered to 83.3% based on 1 hour after filtration concentration. Table 1 summarizes the results.

<Example 2>
Filtration concentration and washing were performed using a membrane module using a bundle of polyvinylidene fluoride hollow fiber membranes coated with poly N-isopropylacrylamide as a separation membrane. Washing was performed according to the procedure of Washing Method 2.

The permeation rate of ethanol after 1 hour of filtration concentration was 0.24 kgm ⁻² h ⁻¹ and the permeation rate of water was 0.32 kgm ⁻² h ⁻¹ . The ethanol permeation rate after filtration concentration 7 days was 0.05 kgm ⁻² h ⁻¹ and the water permeation rate was 0.11 kgm ⁻² h ⁻¹ .

And the permeation | transmission rate of ethanol after the washing | cleaning by the washing | cleaning method 1 was 0.22 kgm ^<-2 > h ^{< -1} >, and the permeation | transmission rate of water was 0.30 kgm ^<-2 > h ^{< -1} >. The ethanol permeation rate was recovered to 91.7% based on 1 hour after filtration concentration. Table 1 summarizes the results.

<Comparative Example 1>
The membrane module using the polyvinylidene fluoride hollow fiber membrane bundle as the separation membrane was used for filtration concentration and washing. Washing was performed according to the procedure of Washing Method 1.

The permeation rate of ethanol after 1 hour of filtration concentration was 0.25 kgm ⁻² h ⁻¹ , and the permeation rate of water was 1.02 kgm ⁻² h ⁻¹ . After 7 days of filtration and concentration, the permeation rate of ethanol was 0.03 kgm ⁻² h ⁻¹ and the permeation rate of water was 0.42 kgm ⁻² h ⁻¹ .

And the permeation | transmission rate of ethanol after the washing | cleaning by the washing | cleaning method 1 was 0.04kgm ^<-2 > h- ¹ , and the permeation | transmission rate of water was 0.45kgm ^<-2 > h- ¹ . The ethanol permeation rate recovered only 16.0% on the basis of 1 hour after concentration by filtration. Table 1 summarizes the results.

<Comparative example 2>
The membrane module using the polyvinylidene fluoride hollow fiber membrane bundle as the separation membrane was used for filtration concentration and washing. Washing was performed according to the procedure of Washing Method 2.

The permeation rate of ethanol after 1 hour of filtration concentration was 0.25 kgm ⁻² h ⁻¹ , and the permeation rate of water was 1.02 kgm ⁻² h ⁻¹ . After 7 days of filtration and concentration, the permeation rate of ethanol was 0.03 kgm ⁻² h ⁻¹ and the permeation rate of water was 0.42 kgm ⁻² h ⁻¹ .

And the permeation | transmission rate of ethanol after the washing | cleaning by the washing | cleaning method 1 was 0.12 kgm ^<-2 > h ^{< -1} >, and the permeation | transmission rate of water was 0.81 kgm ^<-2 > h ^{< -1} >. The permeation rate of ethanol recovered only 48.0% based on 1 hour after concentration by filtration. Table 1 summarizes the results.
<Example 3>
Filtration concentration and washing were performed using a membrane module using a bundle of polyvinylidene fluoride hollow fiber membranes coated with poly N-isopropylacrylamide as a separation membrane. Washing was performed according to the procedure of Washing Method 1.

The permeation rate of butanol after 1 hour of filtration and concentration was 0.08 kgm ⁻² h ⁻¹ , and the permeation rate of water was 0.30 kgm ⁻² h ⁻¹ . The butanol concentration in the fermentation broth at this time was 1.0% by weight.

And the permeation | transmission rate of butanol 7 days after filtration concentration was 0.02 kgm ^<-2 > h ^{< -1} >, and the permeation | transmission rate of water was 0.12 kgm ^<-2 > h- ¹ . At this time, the concentration of butanol in the fermentation broth was 1.7% by weight.

The permeation rate of ethanol after washing by the washing method 1 was 0.07 kgm ⁻² h ⁻¹ and the permeation rate of water was 0.27 kgm ⁻² h ⁻¹ . At this time, the butanol concentration in the fermentation broth was 2.2% by weight. The permeation rate of ethanol was recovered to 87.5% based on 1 hour after concentration by filtration. Table 2 summarizes the results.
<Comparative Example 3>
The membrane module using the polyvinylidene fluoride hollow fiber membrane bundle as the separation membrane was used for filtration concentration and washing. Washing was performed according to the procedure of Washing Method 1.

The permeation rate of butanol after 1 hour of filtration and concentration was 0.04 kgm ⁻² h ⁻¹ , and the permeation rate of water was 0.98 kgm ⁻² h ⁻¹ . The butanol concentration in the fermentation broth at this time was 1.0% by weight.

And the permeation | transmission rate of butanol 7 days after filtration concentration was 0.001, and the permeation | transmission rate of water was 0.45 kgm ^<-2 > h- ¹ . At this time, the butanol concentration in the fermentation broth was 1.2% by weight.

The permeation rate of butanol after washing by the washing method 1 was 0.01 kgm ⁻² h ⁻¹ and the permeation rate of water was 0.48 kgm ⁻² h ⁻¹ . At this time, the butanol concentration in the fermentation broth was 1.2% by weight. The butanol permeation rate recovered only 25.0% on the basis of 1 hour after filtration concentration. Table 2 summarizes the results.

  The production method and apparatus of the present invention can be suitably used in a sugar fermentation alcohol production process in which alcohol concentration of a sugar fermentation liquid is continuously performed.

It is an apparatus figure which shows the outline of the fermentation and the membrane filtration apparatus used in Example 1 in order to implement this invention method.

Explanation of symbols

1: Fermenter 2: Pump 3: Heater 4: Membrane module 4A: Supply port 4B: Outlet 4C: Permeate inlet 4D: Permeate outlet 5: Storage tank 6: Pump 7: Valve

Claims (7)

  In the method of producing alcohol by filtering and concentrating alcohol-containing fermented liquor obtained by fermenting sugar with a separation membrane, using a separation membrane having a thermosensitive polymer on the surface, filtration concentration and washing of the separation membrane are repeated. Performing filtration concentration, the temperature at the time of filtration concentration is not less than the lower critical solution temperature of the thermosensitive polymer, and the temperature at the time of washing the separation membrane is less than the lower critical solution temperature of the thermosensitive polymer. An alcohol production method.   2. The alcohol production method according to claim 1, wherein the separation membrane is washed by backwashing.   The alcohol production method according to claim 1 or 2, wherein the obtained filtrate is further filtered and concentrated with a filtration device provided with a separation membrane having a thermosensitive polymer in the surface layer.   The alcohol production method according to claim 1, wherein the alcohol is butanol.   An alcohol production apparatus comprising a fermenter for sugar fermentation and a membrane filtration device for filtering and concentrating the fermentation liquor produced in the fermenter, the membrane filtration device having a thermosensitive polymer on the surface layer And a device for adjusting the temperature of the separation membrane and / or a device for heating the fermentation broth sent to the separation membrane and / or a device for cooling the backwashing solution. Alcohol production equipment.   The alcohol production apparatus according to claim 5, wherein a membrane filtration device provided with a separation membrane having a temperature-sensitive polymer as a surface layer is immersed in the fermenter.   A membrane filtration device equipped with a separation membrane having a thermosensitive polymer on its surface layer is immersed in the fermentation tank, and a filtration device equipped with a separation membrane having a temperature sensitive polymer on its surface layer is installed outside the fermentation tank The apparatus for producing alcohol according to claim 5 or 6.

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