JP2011223975A - Method and apparatus for producing sugar solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to filter a sugar solution without clogging of a membrane with solid components derived from biomass, when purifying the sugar solution by concentrating the sugar solution derived from cellulose-containing biomass using a nanofiltration membrane or a reverse osmosis membrane.SOLUTION: There are provided a method for producing the sugar solution by purifying an enzymatically saccharified solution derived from the cellulose-containing biomass by using a multiporous microfiltration membrane having a specific average pore size, subsequently the nanofiltration membrane and/or the reverse osmosis membrane, and an apparatus for producing the sugar solution.

Description

  The present invention relates to a method for producing a sugar solution from biomass containing cellulose and an apparatus for producing the sugar solution.

  BACKGROUND ART Fermentative production processes for chemicals using sugar as a raw material are used for producing various industrial raw materials. Currently, sugar derived from edible raw materials such as sugar cane, starch and sugar beet is used industrially as sugar for this fermentation raw material, but the price of edible raw materials will rise due to the increase in the world population in the future, or it will compete with edible foods. From the ethical aspect of building a process for producing sugar solution more efficiently than renewable non-edible resources, that is, biomass, or building a process for efficiently converting the obtained sugar solution into fermentation raw materials Is an issue for the future.

  Conventional techniques for obtaining sugar from biomass include a method of hydrolyzing cellulose and hemicellulose in biomass to monosaccharides typified by glucose and xylose using concentrated sulfuric acid (Patent Documents 1 and 2), and biomass reactivity. In general, a method of hydrolyzing by an enzymatic reaction after performing a pretreatment for improving the pH is known (Patent Documents 3 and 4).

  However, since the sugar solution derived from biomass obtained by these conventional methods has a low sugar concentration, it takes time in the fermentation process, and there is a problem that extra energy is consumed in the subsequent distillation process. Moreover, since many fermentation-inhibiting substances derived from biomass are contained, there is also a problem that fermentation efficiency is poor.

  As one method for solving these problems, a parallel double fermentation technique has been studied (Patent Document 5). The technology that does not perform solid-liquid separation has the advantage that the sugar is consumed by fermentation in the enzyme reaction, which is an equilibrium reaction, and therefore has the advantage of a high sugar production rate, but because fermentation-inhibiting substances derived from biomass accumulate. There was a problem that the accumulated concentration of chemicals did not increase and the production efficiency did not increase.

  On the other hand, in a process for obtaining a sugar solution, a method of using a nanofiltration membrane or a reverse osmosis membrane for concentration or purification of sugar is disclosed (Patent Document 6). However, when these membranes are used for filtration, there is a problem that the membrane is clogged due to biomass-derived solids contained in the sugar solution, making filtration difficult. Therefore, before being subjected to membrane filtration, as a method of removing this solid matter, for example, a method using a screw press or a filter press (Patent Document 7), a method using centrifugation (Patent Document 8), a method of filtering with a nonwoven fabric ( Patent Document 9) and the like have been studied. However, in these methods, the solid content contained in the biomass-derived sugar solution cannot be sufficiently removed, and the membrane is clogged when the sugar solution is filtered using a nanofiltration membrane or a reverse osmosis membrane. The issue was unsolved.

Japanese National Patent Publication No. 11-506934 JP 2005-229821 A JP 2001-95597 A Japanese Patent No. 3041380 JP 2009-22165 A International Publication No. 2009/110374 Japanese National Patent Publication No. 9-507386 JP 61-234790 A JP 2009-240167 A

  The present invention solves the above-described problem, and when a biomass-derived sugar solution is concentrated and purified by a nanofiltration membrane or a reverse osmosis membrane, the membrane is filtered without clogging the membrane due to biomass-derived solid content. Make it possible to do.

  As a result of intensive studies to solve the above-mentioned problems, a substance that causes the filtration of the membrane is found when the sugar is concentrated and purified by a nanofiltration membrane and / or reverse osmosis membrane, and has a specific average pore size. The inventors have found that removal of a porous microfiltration membrane using a porous microfiltration membrane can prevent clogging of the filtration membrane, thereby completing the present invention. Furthermore, by performing the water treatment during filtration with a porous microfiltration membrane, the membrane clogging in the microfiltration membrane filtration is improved, and a high-quality sugar solution with reduced fermentation inhibitor concentration can be obtained efficiently. I found out that I can do it.

That is, the present invention has the following configurations [1] to [8].
[1] A method for producing a sugar solution from cellulose-containing biomass,
Step (1) for obtaining an enzyme saccharified solution by adding a saccharifying enzyme to a pretreated product obtained by pretreating cellulose-containing biomass, and the enzyme saccharified solution obtained in step (1) have an average pore size of 0.25 μm. Cross-flow filtration through the following porous microfiltration membrane to obtain a sugar solution as a membrane permeate fraction (2), the sugar solution obtained in step (2) is passed through the nanofiltration membrane and / or reverse osmosis membrane And a step (3) of obtaining a sugar solution purified as a membrane-impermeable fraction.
[2] The method for producing a sugar liquid according to [1], wherein in the step (2), the water treatment is performed before or during the crossflow filtration.
[3] In the step (2), the water treatment is performed so that the MLSS concentration of the enzyme saccharified solution is 40000 mg / L or less before or during the crossflow filtration. Method for producing a sugar solution.
[4] The method for producing a sugar liquid according to any one of [1] to [3], wherein in the step (2), the pH of the enzyme saccharified liquid is changed and then cross-flow filtration is performed.
[5] Production of sugar solution according to any one of [1] to [4], wherein in step (1), the pretreatment is hydrothermal treatment and a pretreated product containing a hot water-soluble component is used. Method.
[6] The method for producing a sugar liquid according to any one of [1] to [5], wherein the solid content of the enzyme saccharified liquid in the step (1) is 0.1% to 10%.
[7] As a previous step of step (2), the enzyme saccharified solution obtained in step (1) is subjected to one or more solid-liquid separation treatments selected from centrifugation, sedimentation separation, and flotation separation. [6] The method for producing a sugar liquid according to any one of [6].
[8] An apparatus for producing a sugar solution from cellulose-containing biomass,
An enzyme saccharification tank having a pretreatment product supply unit for supplying a pretreatment product of cellulose-containing biomass and a saccharification enzyme supply unit for supplying a saccharification enzyme;
Viscometer for measuring the viscosity of the enzyme saccharified solution, a hydration / drainage control unit that performs hydration and / or drainage according to the measured viscosity value of the enzyme saccharified solution, and a porous precision with an average pore size of 0.25 μm or less A membrane separation tank having a filtration membrane, a cross-flow filtration of the enzyme saccharified solution obtained in the enzyme saccharification tank to obtain a sugar solution as a membrane permeation fraction, and a nanofiltration membrane and / or a reverse osmosis membrane, A sugar solution purification unit for filtering the sugar solution obtained in the membrane separation tank to obtain a sugar solution purified as a membrane non-permeating fraction,
An apparatus for producing a sugar solution comprising:

  According to the present invention, when a sugar solution is produced by filtration through a nanofiltration membrane and / or a reverse osmosis membrane, solid content derived from biomass can be sufficiently removed, so that the membrane is not clogged. It becomes possible to filter, and it is possible to efficiently produce a high-quality biomass-derived sugar solution used for fermentative production of chemicals.

It is the schematic which shows an example of the manufacturing apparatus of the sugar liquid of this invention. It is the schematic which shows an example of the manufacturing apparatus of the sugar liquid of this invention. It is the schematic which shows an example of the manufacturing apparatus of the sugar liquid of this invention. It is the schematic which shows an example of the manufacturing apparatus of the sugar liquid of this invention. It is a graph which shows the particle size distribution of the particle component contained in the hydrothermal treatment saccharified liquid. It is the electron micrograph which observed the particle component adhering to the nanofiltration membrane after filtration.

  In the present invention, a saccharification enzyme is added to a pretreated cellulose-containing biomass pretreated product to obtain an enzyme saccharified solution, which is subjected to crossflow filtration using a porous microfiltration membrane, and then a membrane permeation fraction. The sugar solution obtained as described above is subjected to a nanofiltration membrane and / or a reverse osmosis membrane to remove fermentation-inhibiting substances, and a sugar solution purified as a membrane-impermeable fraction is obtained.

  In the present invention, the cellulose-containing biomass is a biological resource containing 5% or more of cellulose. Specific examples include herbaceous biomass such as bagasse, switchgrass, napiergrass, Eliansus, corn stover, rice straw, and straw, and woody biomass such as trees and waste building materials. These cellulose-containing biomass is also called lignocellulose because it contains lignin and cellulose / hemicellulose which are aromatic polymers. By hydrolyzing cellulose and hemicellulose, which are polysaccharide components contained in cellulose-containing biomass, a sugar solution containing a monosaccharide that can be used as a fermentation raw material can be obtained.

  In the method for producing a sugar solution of the present invention, step (1) is a step of pretreating cellulose-containing biomass and hydrolyzing the pretreated product obtained as a result in the presence of a saccharifying enzyme to obtain an enzyme saccharified solution. is there.

  In the pretreatment in step (1), the biomass containing cellulose is subjected to physical and chemical treatments in order to improve the hydrolysis efficiency by the saccharifying enzyme. This pretreatment includes acid treatment with high-temperature and high-pressure dilute sulfuric acid, sulfite, etc., alkali treatment with an alkaline aqueous solution such as calcium hydroxide and sodium hydroxide, ammonia treatment with liquid ammonia or ammonia gas, Hydrothermal treatment with hydrothermal water, fine pulverization treatment that mechanically cuts fibers using a cutter mill, hammer mill, grinder, etc., steam for a short time with steam, release pressure instantly and pulverize by volume expansion Examples include, but are not limited to, steaming and explosion treatment.

  Among the pretreatments in step (1), the acid treatment is a treatment method in which an acidic aqueous solution such as sulfuric acid or sulfite and cellulose-containing biomass are treated under high temperature and high pressure conditions to obtain a pretreated product. In general, the acid treatment is characterized by dissolving lignin, first hydrolyzing from the hemicellulose component having low crystallinity, and then decomposing the cellulose component having high crystallinity, and thus contains a large amount of xylose derived from hemicellulose. It is possible to obtain a liquid. Further, by setting two or more steps, hydrolysis conditions suitable for hemicellulose and cellulose can be set, and the decomposition efficiency and sugar yield can be improved.

  The acid used in the acid treatment is not particularly limited as long as it causes hydrolysis, but sulfuric acid is desirable from the viewpoint of economy. The acid concentration is preferably 0.1 to 15% by weight, and more preferably 0.5 to 5% by weight. The reaction temperature can be set in the range of 100 to 300 ° C. The reaction time can be set in the range of 1 second to 60 minutes. The number of processes is not particularly limited, and may be performed once or more. The decomposition by the saccharifying enzyme after the acid treatment may be carried out separately for the pretreatment product obtained after the acid treatment by separating the solid content and the liquid component, or may be performed while the solid content and the liquid component are mixed. . Since the solid component and the liquid component obtained by the acid treatment contain the acid used, neutralization is performed to perform a hydrolysis reaction with a saccharifying enzyme.

  Among the pretreatments in step (1), hydrothermal treatment is a method of treating with pressurized hot water at 100 to 400 ° C. for 1 second to 60 minutes. Usually, it is performed so that the cellulose-containing biomass after the treatment has a concentration of 0.1 to 50% by weight. The pressure is not particularly limited because it depends on the treatment temperature, but it is preferably 0.01 to 10 MPa.

  In hydrothermal treatment, the elution component to hot water differs depending on the temperature of the pressurized hot water. In general, as the temperature of pressurized hot water is increased, the first group of tannin and lignin flows out from the cellulose-containing biomass first, and then the second group of hemicellulose flows out at 140-150 ° C. or higher. When the temperature exceeds about 230 ° C., the third group of cellulose flows out. Moreover, the hydrolysis reaction of hemicellulose and cellulose may occur simultaneously with the outflow. In order to improve the reaction efficiency of the saccharifying enzyme with respect to cellulose and hemicellulose using the difference in the outflow component depending on the temperature of the pressurized hot water, the treatment temperature may be changed to perform multi-stage treatment. Here, among the fractions obtained by hydrothermal treatment, an aqueous solution containing a component eluted into pressurized hot water is referred to as a hot water-soluble component, and a hot water-soluble component is referred to as a hot water-insoluble component.

  The hot water-insoluble component is a solid component mainly containing a cellulose (C6) component having two or more sugars, which is obtained as a result of elution of many lignin and hemicellulose components. In addition to cellulose as the main component, hemicellulose components and lignin components may be included. These content ratios change with the temperature of the pressurized hot water of hydrothermal treatment, and the kind of process biomass. The water content of the hot water insoluble component is 10% to 90%, more preferably 20% to 80%.

  The hot water-soluble component is an aqueous solution containing hemicellulose, lignin, tannin, and a part of cellulose components eluted in pressurized hot water in a liquid state or a slurry state, and is in a liquid state or a slurry state. The content rate of the eluted component in the hot water soluble component is usually 0.1% or more and 10% or less (% by weight). Here, the measurement of the content rate of the elution component in the hot water-soluble component can be performed using a moisture content meter (for example, an infrared moisture meter FD720 manufactured by Kett Science Laboratory). Specifically, a value obtained by subtracting from 100% the moisture content obtained with a moisture meter for the hot water soluble component to be measured can be used. The elution components are not limited to water-soluble components such as monosaccharides and oligosaccharides, but are all components that are mixed in water. Also included are colloidal components.

  In particular, hot water-soluble components contain a large amount of organic acids such as formic acid and acetic acid, which are fermentation inhibitors, and furan and aromatic compounds such as HMF and furfural. It is usually difficult to carry out fermentative production of chemicals using the sugar solution as it is. In addition, the components contained in the hot water-soluble component contain a large amount of colloidal components and fine particle components, and these may cause clogging in filtration using a membrane.

  Among the pretreatments in step (1), the alkali treatment is a treatment method in which cellulose-containing biomass is reacted with an aqueous alkali solution, usually an aqueous solution of a hydroxide salt (excluding ammonium hydroxide). By the alkali treatment, it is possible to remove lignin that mainly inhibits the reaction of cellulose / hemicellulose by saccharifying enzymes. The hydroxide salt used is preferably sodium hydroxide or calcium hydroxide. The concentration of the aqueous alkali solution is preferably in the range of 0.1 to 60% by weight, and this is added to the cellulose-containing biomass and is usually treated at a temperature range of 100 to 200 ° C, preferably 110 to 180 ° C. The number of treatments is not particularly limited, and may be performed once or a plurality of times. When performing twice or more, you may implement each process on different conditions. Since the pretreated product obtained by the alkali treatment contains an alkali, it is neutralized before hydrolysis with a saccharifying enzyme.

  Among the pretreatments in step (1), ammonia treatment is a treatment method in which an aqueous ammonia solution or 100% ammonia (liquid or gas) is reacted with cellulose-derived biomass. For example, the method described in JP2008-161125A or JP2008-535664A can be used. In the ammonia treatment, it is said that the reaction efficiency with the saccharifying enzyme is greatly improved by the fact that the crystallinity of cellulose is lost due to the reaction of ammonia with the cellulose component. Usually, ammonia is added to the cellulose-containing biomass so as to have a concentration in the range of 0.1 to 15% by weight with respect to the cellulose-containing biomass, and the treatment is performed at 4 ° C to 200 ° C, preferably 60 ° C to 150 ° C. The number of treatments is not particularly limited, and may be performed once or a plurality of times. The pretreated product obtained by the ammonia treatment is neutralized or removed from ammonia before performing a hydrolysis reaction with a saccharifying enzyme. The acid reagent used for neutralization is not particularly limited. For example, although it can neutralize with acids, such as hydrochloric acid, nitric acid, and a sulfuric acid, a sulfuric acid is preferable considering that it does not become a corrosiveness of a process piping, and does not become a fermentation inhibition factor. Ammonia can be removed by volatilizing ammonia by keeping the ammonia-treated product in a reduced pressure state.

  In step (1) of the present invention, a saccharification enzyme is added to the pretreated product obtained by performing the above pretreatment to perform a hydrolysis reaction to obtain an enzyme saccharified solution.

  The hydrolysis reaction with a saccharifying enzyme is preferably performed in the vicinity of pH 3 to 7, more preferably pH 4.0 or more and 6.0 or less. The reaction temperature is preferably 40 to 70 ° C. The pH can be adjusted by appropriately adding an acid or alkali, or by adding a pH buffer such as acetate or citrate. Preferably, from an economical viewpoint and a fermentation inhibition viewpoint, sulfuric acid is used as an acid, and an aqueous solution of any one of sodium hydroxide, calcium hydroxide, or ammonia is used as an acid so that the desired pH is obtained while measuring the pH during the reaction. It is preferable to add the above acid and alkali appropriately over time. The hydrolysis reaction time by the saccharifying enzyme is preferably 1 hour or more and 72 hours or less from the viewpoint of yield, and more preferably 3 hours or more and 24 hours or less from the viewpoint of energy used. The reaction apparatus used for the hydrolysis may be a single stage or multiple stages, and may be a continuous type.

  In the present invention, the saccharifying enzyme refers to an enzyme component having an activity of degrading cellulose or hemicellulose or assisting in degrading cellulose or hemicellulose. Specific examples of enzyme components include cellobiohydrolase, endoglucanase, exoglucanase, β-glucosidase, xylanase, xylosidase, and biomass swelling enzyme. The saccharifying enzyme is preferably an enzyme mixture containing a plurality of these components. For example, the hydrolysis of cellulose and hemicellulose is preferably used in the present invention because it can be efficiently carried out by the concerted effect or the complementary effect of such a plurality of enzyme components.

  In the present invention, those produced by microorganisms can be preferably used as the saccharifying enzyme. For example, it may be a saccharifying enzyme containing a plurality of enzyme components produced by one kind of microorganism, or may be a mixture of enzyme components produced from a plurality of microorganisms.

  The microorganism that produces a saccharifying enzyme is a microorganism that produces a saccharifying enzyme inside or outside the cell, and preferably a microorganism that produces a saccharifying enzyme outside the cell. This is because saccharifying enzyme recovery is easier for microorganisms produced outside the cell.

  The microorganism that produces the saccharifying enzyme is not particularly limited as long as it produces the above enzyme components. In particular, filamentous fungi classified into the genus Trichoderma secrete a large amount of various saccharifying enzymes to the outside of the cells, so that they can be particularly preferably used as microorganisms that produce saccharifying enzymes.

  The saccharifying enzyme used in the present invention is preferably a saccharifying enzyme derived from Trichoderma. Specifically, a saccharifying enzyme derived from Trichoderma reesei is more preferable, and more specifically, Trichoderma reesei QM9414 (Trichoderma reesei QM9414), Trichoderma reesei QM9123 (Trichoderma Risei RutC-30 (Trichoderma reeseiRut C-30), Trichoderma reesei PC3-7 (Trichoderma reesei PC3-7), Trichoderma reesei CL-847 (Trichoderma reesei CL-847), Trichoderma richo MC (77) A saccharifying enzyme derived from a genus Trichoderma such as Ma. Reesei MCG80 (Trichoderma reesei MCG80) or Trichoderma viride QM9123 (Trichoderma violet 9123) is preferable. Further, it may be a saccharifying enzyme derived from a mutant strain in which Trichoderma filamentous fungi are subjected to a mutation treatment with a mutagen or ultraviolet irradiation to improve the productivity of the saccharifying enzyme. For example, it may be a saccharifying enzyme in which the composition ratio of the saccharifying enzyme is changed, derived from a mutant strain in which Trichoderma filamentous fungus is modified so that a part of the enzyme component is expressed in a large amount.

  A commercially available saccharifying enzyme derived from Trichoderma sp. May be used. For example, Novozyme's “Ceric Cec”, Genencor Kyowa's “Accel Race 1000”, “Accel Race 1500”, Sigma-Aldrich “Cellulase from Trichoderma reesei ATCC 26921”, “Cellulase from Trichoderma viride”, “ “Cellulase from Trichoderma longibrachiatum” and the like.

  The saccharifying enzyme derived from Trichoderma can be obtained by culturing Trichoderma for an arbitrary period in a medium prepared to produce enzyme components. The medium component to be used is not particularly limited, but a medium to which cellulose is added can be preferably used in order to promote production of saccharifying enzyme. Further, the culture supernatant is preferably used as it is or from the culture supernatant from which Trichoderma cells are removed. Furthermore, a protease inhibitor, a dispersant, a dissolution accelerator, a stabilizer and the like may be added as additives for stabilizing the enzyme.

  The kind of each enzyme component in the saccharifying enzyme derived from Trichoderma sp., And its component ratio are not particularly limited. For example, the culture solution derived from Trichoderma reesei contains cellobiohydrolase, β-glucosidase, and the like. In the case of Trichoderma spp., Highly active cell biohydrolase is produced in the culture solution, but β-glucosidase is retained in the cell or on the cell surface, so the β-glucosidase activity in the culture solution is low, In this case, a different or the same type of β-glucosidase may be further added to the culture supernatant. As the heterogeneous β-glucosidase added here, β-glucosidase derived from Aspergillus can be preferably used. Examples of β-glucosidase derived from Aspergillus sp. Include “Novozyme 188” commercially available from Novozyme.

  The microfiltration membrane used in step (2) of the method for producing a sugar liquid of the present invention is a porous membrane having a functional average pore diameter of 0.25 μm or less. By using a porous microfiltration membrane having an average pore diameter of 0.25 μm or less, clogging due to solid components in the step (2) and step (3) of the present invention, solid components in the enzyme saccharified solution or sugar solution, etc. And stable filtration becomes possible, and as a result, the fermentation inhibitor can be efficiently removed, so that a high-quality sugar solution for fermentation can be obtained. From the viewpoint of operability when filtering a solution having a high saccharifying enzyme concentration and preventing a decrease in sugar yield, it is preferable to use a porous microfiltration membrane having an average pore diameter of 0.01 μm or more and 0.25 μm or less.

  The microfiltration membrane used in step (2) of the present invention is a membrane having a functional surface. The porous microfiltration membrane refers to a membrane having a three-dimensional network structure in which voids whose functional surfaces communicate with each other are formed. For example, the membrane functional surface is not woven or non-woven. However, a woven fabric or a non-woven fabric may be used for the non-functional substrate. This is because it has been found in the present invention that when the membrane functional surface is a woven fabric or a nonwoven fabric, it is difficult to effectively remove the particle component having a particle size of 0.25 μm or more.

  The average pore diameter of the microfiltration membrane may be the nominal diameter suggested by each separation membrane manufacturer, or may be actually measured. As a method for measuring the pore size of the microfiltration membrane, a direct observation method or a bubble point method can be applied. In the direct observation method, a scanning electron microscope (SEM) is used to observe the surface pores existing within the range of 10 μm × 9 μm on the surface of the microfiltration membrane, the diameter is measured, and the average value is obtained to obtain the average value. The pore diameter can be calculated. In the bubble point method, air pressure is applied from the secondary side of the membrane, the minimum pressure at which bubble formation can be observed is measured, and the average pore diameter is calculated from the relationship between the surface tension and pressure of the liquid used. can do. More specifically, it is possible to measure in accordance with ASTM F316-03 (Bubble Point Method), for example, using a through-hole distribution / gas permeability analyzer manufactured by Nippon Bell Co., Ltd. be able to.

  Examples of the material for the microfiltration membrane used in the present invention include cellulose, aromatic polyamide, polyvinyl alcohol, polysulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate, polytetrafluoroethylene, ceramics, and metal. be able to. Among these, since it is not affected by the saccharifying enzyme contained in the enzyme saccharified solution and has good removability of insoluble solids, aromatic polyamide, polyvinyl alcohol, polysulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, Polycarbonate and polytetrafluoroethylene are preferable, and polyvinylidene fluoride is particularly preferable.

  The cross-flow filtration performed in the step (2) of the present invention is a method in which a liquid flow parallel to the membrane surface is formed and the liquid surface is washed while washing the liquid surface using a stock solution circulation by a pump or a liquid flow by aeration. In the undiluted solution circulation by the pump, it is preferable to use a hollow fiber membrane or a hollow membrane module, and in the liquid flow by aeration, it is preferable to use an immersion type flat membrane module. More preferably, a hollow fiber type module capable of causing mechanical vibration of the membrane by aeration while circulating the stock solution with a pump is used. When using a hollow fiber type module, it is preferable to perform solid-liquid separation in advance using centrifugal separation or the like. Centrifugation can prevent the cellulose component from becoming entangled with the hollow fiber and hindering long-term operation. The gas used for aeration is generally air, but the film surface may be removed by washing the film surface with a reactive gas such as ozone gas. Moreover, the pH of the enzyme saccharified solution to be filtered can be lowered by aeration using carbon dioxide.

  In the cross flow filtration performed in the step (2) of the present invention, from the viewpoint of preventing membrane clogging, the membrane permeation flux (described later) is controlled to 0.75 m / day or less, more preferably 0.5 m / day or less. Is preferred. For example, in an enzyme saccharified solution containing a hydrothermally heat-soluble component of hydrothermal treatment, it is particularly preferable to operate at a membrane permeation flux of 0.1 m / day or less. In order to easily control the membrane permeation flux of the crossflow filtration, a water treatment described later is performed before or during the crossflow filtration, or a solid-liquid separation process before the crossflow filtration. It is effective to perform (described later). When performing a solid-liquid separation process, it is preferable to perform a hydration process after a solid-liquid separation process.

  It is preferable to carry out the water treatment before or during the cross flow filtration using the microfiltration membrane in the step (2) of the present invention. The hydration process is a process of adding water having a turbidity of 10 NTU or less to the enzyme saccharified solution. As the water to be added, from the viewpoint of reducing the amount of water used in the production process, the filtrate in the step (3) further subjected to the reverse osmosis membrane treatment may be reused.

  In the case of performing the water treatment in the step (2) of the present invention, it is preferable to determine the amount of water so as to obtain a desired MLSS concentration. The MLSS (Mixed Liquor Suspended Solid) concentration generally represents a concentration relating to insoluble solids in a liquid, and can be measured according to a method defined in the standard of JIS K0102 14.1 (2008). When the MLSS concentration becomes a certain value or more, the filterability is deteriorated particularly when the cross flow filtration is continuously performed for a certain time or more. Therefore, it is preferable to perform the water treatment so that the MLSS concentration becomes a certain value or less. Specifically, the MLSS concentration of the enzyme saccharified solution is preferably 40000 mg / L or less. The preferable range of MLSS concentration is preferably 500 mg / L or more and 40000 mg / L or less, more preferably 1000 mg / L or more and 20000 mg / L or less. When the MLSS concentration is 500 mg / L or less, a decrease in filterability does not appear remarkably, so that the water treatment need not be performed.

  The MLSS concentration of the enzymatic saccharified solution is difficult to directly measure, for example, when continuously operating. For example, instead of the MLSS concentration, the viscosity correlated with the MLSS concentration is measured, and the amount of water is determined using this as an index. be able to. The method for measuring the viscosity of the enzyme saccharified solution is not particularly limited. For example, it can be measured using a generally available viscometer.

  The amount of water added in the hydrolysis treatment can be determined by measuring the MLSS concentration and viscosity of the enzyme saccharified solution as described above. The amount is preferably 10 times, more preferably 1.0 to 5.0 times.

  Moreover, it is good to perform a hydrolysis process before the crossflow filtration of a process (2), or during filtration. The hydration may be performed on either the non-permeation side or the permeation side of the microfiltration membrane. When water is added on the permeate side, the effect of backwashing the membrane can also be obtained. Can be suppressed. Further, when water is added on the non-permeating side, an effect of washing the membrane surface can be expected.

  The hydration treatment is also related to the removal effect of the fermentation inhibitor by filtration through the nanofiltration membrane and / or reverse osmosis membrane in step (3). For example, a furfural concentration of 0.5 g / L, which is a fermentation inhibitor (a low concentration that does not cause a decrease in fermentation efficiency when ethanol fermentation is performed using a sugar solution obtained by the present invention. JP Delgenes et al., 1996, vol 19, 220-225, “Enzyme and Microbiology”), the operability of the cross flow filtration in the step (2) is improved, and in the step (3) The fermentation inhibitor can be effectively removed.

  Prior to the cross flow filtration in step (2) of the present invention, the enzyme saccharified solution may be subjected to a solid-liquid separation treatment. The solid-liquid separation process is a process for removing a part of insoluble components present in the enzyme saccharified solution. Specific methods for solid-liquid separation include centrifuge method, squeeze separation method, filtration method, flotation separation method, and sedimentation separation method according to “Food Engineering Basic Course Solid-Liquid Separation” (Kohrin). Among these, since there is no risk of clogging of the filter or membrane during filtration due to insoluble components, centrifugation, sedimentation separation or flotation separation, or a combination of these is preferred, more preferably from the viewpoint of exclusive area and equipment costs Centrifuge. The solid-liquid separation process may be performed intermittently or continuously. Further, the flocculant treatment may be performed before the solid-liquid separation treatment. This is because the solid content can be removed more efficiently by the flocculant. The flocculant is not particularly limited, and examples thereof include PAC (polyaluminum chloride), sulfate band, polysilica iron, ferric chloride, and polymer flocculant.

  It is preferable to change the pH of the enzyme saccharified solution before the crossflow filtration in the step (2) of the present invention. Here, changing the pH means adding an acid or alkali to the enzyme saccharified solution to lower or increase the pH of the enzyme saccharified solution. By changing pH, polymer components (impurities) such as fermentation inhibitors that have been dissolved become insoluble and agglomerate to remove them by cross-flow filtration using a microfiltration membrane in step (2). be able to. By removing unnecessary impurities by the cross flow filtration in the step (2), the long-term operability of the nanofiltration membrane and / or the reverse osmosis membrane can be improved in the step (3). The step of changing the pH is not particularly limited as long as it is before cross-flow filtration with a microfiltration membrane, but when performing solid-liquid separation as a previous step of step (2), before the solid-liquid separation treatment. It is preferable to change the pH.

  When changing the pH of the enzyme saccharified solution, the pH is preferably in the range of 1 to 9, more preferably 1 to 7, and even more preferably 1 to 4.5. It is particularly preferable to carry out at a pH of not less than 3 and not more than 4.5. In the case where the pH is lowered to these acidic ranges, an effect of removing the organic acid in the membrane permeation fraction in the step (3) can also be expected. The pH of the enzyme saccharified solution can be lowered by adding an acid such as sulfuric acid or hydrochloric acid. Moreover, raising the pH of an enzyme saccharified liquid can be performed by adding alkalis, such as sodium hydroxide aqueous solution, for example.

  Although the operation method of the cross flow filtration using the microfiltration membrane in the process (2) of this invention is not specifically limited, It is preferable to perform a backwash operation or an intermittent operation. By performing these operations, components that are deposited and concentrated on the membrane surface and block the membrane can be separated from the membrane at the time of backwashing in the backwashing operation or when the intermittent operation is stopped, thereby improving long-term operability. . Although it does not specifically limit as a liquid used for backwashing, Preferably it is water or a filtrate. The water may be tap water or pure water. Furthermore, it is preferable to wash regularly using a chemical | medical agent, when filtering stably for a long term. The drug is not particularly limited, such as acid, alkali, surfactant, enzyme, etc., but is preferably an alkali-containing aqueous solution. More preferred is a sodium hydroxide-containing aqueous solution. The washing method may be either forward washing from the non-permeating side of the membrane or back washing from the permeating side.

  In the present invention, fermentation inhibition refers to fermentation inhibition as compared to the case where a reagent monosaccharide is used as a fermentation raw material when a chemical product is produced using a sugar solution made from cellulose-containing biomass as a raw material for fermentation. This refers to a phenomenon in which the production amount, accumulation amount, or production rate of a chemical product decreases due to a substance. The degree of such fermentation inhibition varies depending on the type of fermentation inhibiting substance present in the sugar solution and the amount thereof, and also varies depending on the type of microorganism used or the type of chemical product. The sugar solution obtained in the step (2) of the present invention has different components and contents depending on the implementation conditions of the step (1) and step (2), the type of cellulose-containing biomass, etc. The fermentation inhibitor can be removed by subjecting the sugar solution to step (3).

  Fermentation inhibitor is a substance produced in a pretreatment step of cellulose-containing biomass or a hydrolysis step using a saccharifying enzyme, and as described above, fermentation inhibition using a sugar solution obtained by the production method of the present invention as a raw material. The substance is classified into organic acids, furan compounds, and phenol compounds.

  Specific examples of the organic acid include acetic acid, formic acid, levulinic acid and the like. Examples of furan compounds include furfural and hydroxymethylfurfural (HMF). These organic acids or furan compounds are products obtained by decomposition of monosaccharides such as glucose or xylose. In addition, examples of phenolic compounds include vanillin, acetovanillin, vanillic acid, syringic acid, gallic acid, coniferyl aldehyde, dihydroconiphenyl alcohol, hydroquinone, catechol, acetogicon, homovanillic acid, 4-hydroxybenzoic acid, 4-hydroxybenzoic acid Specific examples include hydroxy-3-methoxyphenyl derivatives (Hibbert's ketones), and these phenolic compounds are derived from lignin or lignin precursors.

  When using waste building materials or plywood as cellulose-containing biomass, components such as adhesives and paints used in the lumbering process may be included as fermentation inhibitors. Examples of the adhesive include urea resin, melamine resin, phenol resin, and urea melamine copolymer resin. Examples of fermentation inhibitors derived from such adhesives include acetic acid, formic acid, formaldehyde and the like.

  The enzyme saccharified solution obtained in step (1) of the present invention contains at least one of the above substances as a fermentation inhibitor, and usually contains a plurality of kinds. These fermentation-inhibiting substances can be detected and quantified by a general analytical technique such as thin phase chromatography, gas chromatography, and high performance liquid chromatography.

  The nanofiltration membrane used in the step (3) of the present invention is also referred to as a nanofilter (nanofiltration membrane, NF membrane), and “a membrane that transmits monovalent ions and blocks divalent ions”. Is a film generally defined as It is a membrane that is considered to have a minute gap of about several nanometers, and is mainly used to block minute particles, molecules, ions, salts, and the like in water.

  The reverse osmosis membrane used in the step (3) of the present invention is also called an RO membrane, and is a membrane generally defined as “a membrane having a desalting function including monovalent ions”. It is a membrane that is thought to have ultrafine pores of several angstroms to several nanometers, and is mainly used for removing ionic components such as seawater desalination and ultrapure water production.

  In step (3) of the present invention, the sugar solution obtained in step (2) is filtered through a nanofiltration membrane, a reverse osmosis membrane, or both membranes, and purified as a membrane-impermeable fraction. It is the process of obtaining. In step (3), sugars dissolved in the sugar solution, particularly monosaccharides such as glucose and xylose, are blocked or filtered to the non-permeable side, and the fermentation inhibitor is permeated as a membrane permeation fraction (filtrate) to be removed. can do.

  The performance of the nanofiltration membrane and reverse osmosis membrane used in step (3) of the present invention is calculated by calculating the transmittance (%) of the target compound (fermentation inhibitor or monosaccharide) to be evaluated contained in the sugar solution. Can be evaluated. The calculation method of the transmittance (%) is shown in Formula 1.

Transmittance (%) = (concentration of target compound on the permeate side / target compound concentration of non-permeate) × 100
(Equation 1).

  The method for measuring the concentration of the target compound in Formula 1 is not particularly limited as long as it is an analytical technique that can be measured with high accuracy and reproducibility, but high-performance liquid chromatography, gas chromatography, or the like can be preferably used. The nanofiltration membrane and reverse osmosis membrane used in the step (3) of the present invention both preferably have a low monosaccharide permeability, and preferably have a high fermentation inhibitory permeability.

The permeation performance of the nanofiltration membrane and reverse osmosis membrane is as follows. When a 500 mg / L sodium chloride aqueous solution is supplied and filtered at a pressure of 0.3 MPa, the permeation flow rate per membrane unit area, that is, the membrane permeation flux is A film of 0.5 m ³ / m ² / day or more is preferably used. The membrane permeation flux can be calculated by Equation 2 by measuring the permeate amount, the time when the permeate amount was collected, and the membrane area.

Membrane permeation flux (m ³ / m ² / day) = permeate amount / membrane area / water sampling time (formula 2).

  In general, since the nanofiltration membrane has a larger pore size than the reverse osmosis membrane, when using the nanofiltration membrane in the step (3), the amount of the fermentation inhibitor to be excluded by permeation through the membrane is larger than that of the reverse osmosis membrane, It is thought that the amount of monosaccharide that is the target product permeated to the permeate side and lost is also large. This tendency is particularly strong when the sugar concentration is high. On the other hand, when a reverse osmosis membrane is used in the step (3), it is considered that the removal amount of the fermentation inhibitor having a large molecular weight is reduced because the pore diameter is smaller than that of the nanofiltration membrane. Therefore, in the step (3), an appropriate membrane is selected from the nanofiltration membrane and the reverse osmosis membrane according to the content and molecular weight of the main fermentation inhibitor in the sugar solution obtained in the step (2). It is preferable to use them. The type of membrane to be selected is not limited to one, and various types of membranes may be used in combination from nanofiltration membranes and reverse osmosis membranes according to the composition of the sugar solution.

  When a nanofiltration membrane is used in step (3), as the concentration of the monosaccharide trapped on the non-permeation side (concentration side) of the nanofiltration membrane increases, the proportion of monosaccharide lost to the permeation side (filtrate side) increases. May be very high. On the other hand, when a reverse osmosis membrane is used, there is almost no loss of monosaccharide even if the monosaccharide concentration on the membrane non-permeate side is increased. However, from the viewpoint of removing fermentation inhibitors, the reverse osmosis membrane is more suitable for nanofiltration membranes. The performance is better than. Therefore, in the step (3), when a nanofiltration membrane and a reverse osmosis membrane are used in combination, the fermentation inhibitor is first removed using the nanofiltration membrane to a concentration at which it is judged that the sugar loss to the membrane permeation side is small. It is preferable to use a reverse osmosis membrane that can be subsequently concentrated without any loss of monosaccharides.

  The nanofiltration membrane used in the step (3) of the present invention is a cellulose polymer, polyamide, polyester, polyimide, vinyl polymer such as polyvinyl alcohol, polysulfone, sulfonated polysulfone, polyethersulfone, sulfonated polyethersulfone, etc. A film made of any of these polymer materials can be used, and a film containing a plurality of these materials may also be used. In addition, the membrane structure includes an asymmetric membrane having a dense layer on at least one side of the membrane, and gradually having fine pores with larger pore diameters from the dense layer toward the inside of the membrane or the other side, or on the dense layer of the asymmetric membrane. The composite film may be a composite film having a very thin functional layer formed of another material. As the composite membrane, for example, a composite membrane described in JP-A-62-201606 in which a nanofilter composed of a polyamide functional layer is formed on a support membrane made of polysulfone as a membrane material can be used.

  Among these nanofiltration membranes, a composite membrane having a high-pressure resistance, high water permeability, and high solute removal performance and having an excellent potential and a functional layer of polyamide is preferable. In order to maintain durability against operating pressure, high water permeability, and blocking performance, a structure in which polyamide is used as a functional layer and is held by a support made of a porous membrane or nonwoven fabric is suitable. As the polyamide semipermeable membrane, a composite semipermeable membrane having a functional layer of a crosslinked polyamide obtained by polycondensation reaction of a polyfunctional amine and a polyfunctional acid halide on a support is suitable.

  In the nanofiltration membrane having a polyamide as a functional layer, preferable carboxylic acid components of monomers constituting the polyamide include, for example, trimesic acid, benzophenone tetracarboxylic acid, trimellitic acid, pyrometic acid, isophthalic acid, terephthalic acid, naphthalene Aromatic carboxylic acids such as dicarboxylic acid, diphenyl carboxylic acid, pyridine carboxylic acid and the like can be mentioned, but considering solubility in a film forming solvent, trimesic acid, isophthalic acid, terephthalic acid, and mixtures thereof are more preferable.

  Preferred amine components of the monomers constituting the polyamide include m-phenylenediamine, p-phenylenediamine, benzidine, methylenebisdianiline, 4,4′-diaminobiphenyl ether, dianisidine, 3,3 ′, 4- Triaminobiphenyl ether, 3,3 ′, 4,4′-tetraaminobiphenyl ether, 3,3′-dioxybenzidine, 1,8-naphthalenediamine, m (p) -monomethylphenylenediamine, 3,3′- Monomethylamino-4,4′-diaminobiphenyl ether, 4, N, N ′-(4-aminobenzoyl) -p (m) -phenylenediamine-2,2′-bis (4-aminophenylbenzimidazole), 2 , 2′-bis (4-aminophenylbenzoxazole), 2,2′-bis (4-aminophenyl) Sulfonyl benzothiazole) and secondary diamines such as piperazine, and piperidine, or secondary diamines such as these derivatives. Among these, a nanofiltration membrane having a functional layer of cross-linked polyamide containing piperazine or piperidine as a monomer is preferably used because it has heat resistance and chemical resistance in addition to pressure resistance and durability.

  More preferably, it is a polyamide containing the above-mentioned cross-linked piperazine polyamide or cross-linked piperidine polyamide as a main component and a constituent represented by the chemical formula (1). More preferred is a polyamide containing a crosslinked piperazine polyamide as a main component and a component represented by the chemical formula (1). Further, in the chemical formula (1), those having n = 3 are particularly preferably used. Examples of the nanofiltration membrane having a crosslinked piperazine polyamide as a main component and a polyamide containing a component represented by the chemical formula (1) as a functional layer include those described in JP-A No. 62-201606. As a specific example, a crosslinked piperazine polyamide-based nanostructure manufactured by Toray Industries, Inc. having a functional layer composed of a crosslinked piperazine polyamide as a main component and a polyamide containing n = 3 in the chemical formula (1) as a constituent component. A filtration membrane UTC60 may be mentioned.

  The nanofiltration membrane is generally used as a spiral membrane element, but the nanofiltration membrane used in the present invention is also preferably used as a spiral membrane element. Specific examples of preferable nanofiltration membrane elements include, for example, GE SepaDK series, HL series, DL series, and sulfonated polysulfone nanofiltration membranes manufactured by GE Osmonics, which are cellulose acetate-based nanofiltration membranes. NTR7410 manufactured by company, NTR7450, NTR-725HF, NTR7255, NTR725HF manufactured by Nitto Denko Corporation using polyvinyl alcohol as a functional membrane, NF99 or NF99HF of a nanofiltration membrane manufactured by Alfa Laval Corporation using a functional layer of polyamide, and a crosslinked piperazine polyamide NF-45, NF-90, NF-200, NF-270 or NF-400 of a nanofiltration membrane manufactured by Filmtech as a functional layer, or a polyamide containing a crosslinked piperazine polyamide as a main component as a functional layer That, Toray Industries, Inc. manufactured nanofiltration membrane module SU-210, SU-220, SU-600 or SU-610 and the like. More preferably, NF99 or NF99HF of a nanofiltration membrane manufactured by Alfa Laval with a functional layer of polyamide, NF-45, NF-90, NF-200 of a nanofiltration membrane manufactured by Filmtec with a functional layer of a crosslinked piperazine polyamide, or A nanofiltration membrane module SU-210, SU-220, SU-600 or SU-610 manufactured by Toray Industries, Inc., having a functional layer of NF-400 or a polyamide containing a crosslinked piperazine polyamide as a main component, more preferably A nanofiltration membrane module SU-210, SU-220, SU-600, or SU-610 manufactured by Toray Industries, Inc., having a functional layer of a polyamide containing a crosslinked piperazine polyamide as a main component.

  In the filtration with the nanofiltration membrane in the step (3), it is preferable to supply the sugar solution obtained in the step (2) to the nanofiltration membrane in a pressure range of 0.1 MPa to 8 MPa. If the pressure is lower than 0.1 MPa, the membrane permeation rate decreases, and if it is higher than 8 MPa, the membrane may be damaged. Further, when the pressure is used at 0.5 MPa or more and 6 MPa or less, the membrane permeation flux is high, so that the sugar solution can be efficiently permeated and is less likely to affect the membrane damage. It is particularly preferable to use at 1 MPa or more and 4 MPa or less.

  The material of the reverse osmosis membrane used in the step (3) of the present invention is a composite membrane (hereinafter also referred to as a cellulose acetate-based reverse osmosis membrane) or a polyamide functional layer made of a cellulose acetate-based polymer. And a composite membrane (hereinafter also referred to as a polyamide-based reverse osmosis membrane). Here, as the cellulose acetate-based polymer, organic acid esters of cellulose such as cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate and the like, or a mixture thereof and those using mixed esters can be mentioned. It is done. Examples of the polyamide include a linear polymer or a crosslinked polymer having an aliphatic and / or aromatic diamine as a monomer.

  Specific examples of the reverse osmosis membrane used in the step (3) of the present invention include, for example, ultra-low pressure type SUL-G10, SUL-G20 and low pressure type SU, which are polyamide-based reverse osmosis membrane modules manufactured by Toray Industries, Inc. -710, SU-720, SU-720F, SU-710L, SU-720L, SU-720LF, SU-720R, SU-710P, SU-720P, TMG10, TMG20-370, TMG20-400, high pressure type SU-810, SU-820, SU-820L, SU-820FA, the company's cellulose acetate reverse osmosis membrane SC-L100R, SC-L200R, SC-1100, SC-1200, SC-2100, SC-2200, SC-3100 , SC-3200, SC-8100, SC-8200, NTR-759 manufactured by Nitto Denko Corporation R, NTR-729HF, NTR-70SWC, ES10-D, ES20-D, ES20-U, ES15-D, ES15-U, LF10-D, Alfa Laval RO98pHt, RO99, HR98PP, CE4040C-30D, GE GE SepaAG series, AK series, Filmtec BW30-4040, TW30-4040, XLE-4040, LP-4040, LE-4040, SW30-4040, SW30HRLE-4040, KOCH TFC-HR, TFC-ULP, TRISEP ACM- 1, ACM-2, ACM-4 and the like.

  In the step (3) of the present invention, a reverse osmosis membrane having a polyamide material is preferably used. This is because cellulose acetate-based membranes may decompose some of the enzymes used in the previous process when used for a long time, particularly cellulase components, and decompose cellulose as a membrane material.

  As the membrane form of the reverse osmosis membrane used in the step (3), those having an appropriate form such as a flat membrane type, a spiral type and a hollow fiber type can be used.

  In the reverse osmosis membrane having a functional layer of polyamide, the preferred carboxylic acid component and amine component of the monomer constituting the polyamide are the same as those of the nanofiltration membrane having the functional layer of polyamide described above.

  In the filtration using the reverse osmosis membrane in the step (3), it is preferable to supply the sugar solution obtained in the step (2) to the reverse osmosis membrane in a pressure range of 1 MPa to 8 MPa. If the pressure is lower than 1 MPa, the membrane permeation rate decreases, and if it is higher than 8 MPa, the membrane may be damaged. Further, if the filtration pressure is used at 2 MPa or more and 7 MPa or less, the membrane permeation flux is high, so that the sugar solution can be efficiently permeated and is less likely to affect the membrane damage. It is particularly preferable to use at 3 MPa or more and 6 MPa or less.

  In step (3), the fermentation inhibitor is removed from the sugar solution by permeating through the nanofiltration membrane and / or reverse osmosis membrane. Among fermentation inhibitors, HMF, furfural, acetic acid, formic acid, levulinic acid, vanillin, acetovanillin or syringic acid can be preferably permeated and removed. On the other hand, sugar contained in the sugar solution is blocked or filtered out on the non-permeation side of the nanofiltration membrane and / or reverse osmosis membrane.

  The sugar component contained in the refined sugar solution obtained in the step (3) (hereinafter also referred to as a refined sugar solution) is a sugar derived from cellulose-containing biomass, and is essentially hydrolyzed in the step (1). There is no significant change from the sugar component obtained by decomposition. That is, monosaccharides contained in the purified sugar solution of the present invention include glucose and xylose as main components, but disaccharides, oligosaccharides, etc. that were not completely decomposed to monosaccharides in the hydrolysis of step (1). A sugar component may also be included. The ratio of glucose and xylose can vary depending on the hydrolysis step of step (1), and is not limited by the present invention. That is, when hemicellulose is mainly hydrolyzed, xylose becomes the main monosaccharide component, and after hemicellulose decomposition, only the cellulose component is separated and hydrolyzed, and glucose becomes the main monosaccharide component. . In addition, glucose and xylose are included as main monosaccharide components when the decomposition of hemicellulose and the decomposition of cellulose are not particularly performed.

  In addition, before using the refinement | purification sugar liquid obtained at a process (3) as a fermentation raw material, you may once concentrate using the concentration apparatus represented by the evaporator, and also refine | purified sugar liquid is further nanofiltration membrane. The concentration may be increased by filtering with a reverse osmosis membrane, but from the viewpoint of energy reduction for concentration, there is a step of further increasing the concentration of purified sugar solution by filtering with a nanofiltration membrane and / or reverse osmosis membrane. Preferably employed. The membrane used in this concentration step is a filtration membrane that removes ions and low molecular weight molecules by using a pressure difference equal to or higher than the osmotic pressure of the water to be treated as the driving force. For example, cellulose-based cellulose acetate and polyfunctional amine compounds A film in which a polyamide separation functional layer is provided on a microporous support film by polycondensation with a polyfunctional acid halide can be employed. In order to suppress fouling on the surface of the nanofiltration membrane and / or reverse osmosis membrane, the surface of the polyamide separation functional layer is coated with an aqueous solution of a compound having at least one reactive group that reacts with an acid halide group, A low fouling membrane mainly for sewage treatment in which a covalent bond is formed between the acid halogen group remaining on the surface of the separation functional layer and the reactive group can also be preferably used. As the nanofiltration membrane and / or reverse osmosis membrane used in this concentration step, at least, among the nanofiltration membrane and / or reverse osmosis membrane used in step (3), the blocking rate of monosaccharides such as glucose or xylose is higher. Higher ones can be more preferably adopted. Specific examples of the nanofiltration membrane and reverse osmosis membrane used for concentration are the same as those of the nanofiltration membrane and reverse osmosis membrane.

  In the method for producing a sugar solution of the present invention, after cross-flow filtration using a microfiltration membrane in step (2), the resulting sugar solution is passed through an ultrafiltration membrane to remove saccharifying enzyme as a non-permeating fraction, You may use a permeation | fractionation fraction for the filtration process by the nanofiltration membrane and / or reverse osmosis membrane of a process (3). The saccharifying enzyme removed here can be reused by putting it into an enzyme saccharification tank from the viewpoint of economy. The ultrafiltration membrane used here is a membrane having a molecular weight cut-off of usually 500 to 100,000, and is abbreviated as ultrafiltration, UF membrane or the like. Since the ultrafiltration membrane is too small to measure the pore diameter on the membrane surface with an electron microscope or the like, the value of the fractional molecular weight is used as an index of the pore diameter instead of the average pore diameter. Is supposed to do. For example, with respect to the molecular weight cut-off: “A plot of data with the molecular weight of a solute on the horizontal axis and the rejection rate on the vertical axis is called a fraction molecular weight curve. The molecular weight at which the blocking rate is 90% is called the fractional molecular weight of the membrane. (The Membrane Society of Japan, “Membrane Science Experiment Series Volume III, Artificial Membrane”, 92 pages, Editorial Committee / Naofumi Kimura, Shinichi Nakao, Haruhiko Ohya, Tsutomu Nakagawa, 1993, Kyoritsu Shuppan) This is well known to those skilled in the art as an index representing the membrane performance of the outer filtration membrane.

  In the method for producing a sugar solution of the present invention, more preferably, by using an ultrafiltration membrane having a fractional molecular weight in the range of 500 to 40,000, the saccharifying enzyme used for enzymatic saccharification can be efficiently recovered. This is because a saccharifying enzyme is a mixture of many kinds of components, and a saccharifying enzyme having a low molecular weight in the saccharifying enzyme group in the mixture has a molecular weight of about 40000. The form of the ultrafiltration membrane to be used is not particularly limited, and any of a spiral type, a hollow fiber type, a tubular type, and a flat membrane type may be used. The recovered saccharifying enzyme can be reused for hydrolysis in the step (1) to reduce the amount of enzyme used.

  The material of the ultrafiltration membrane is not particularly limited, but cellulose, cellulose ester, polysulfone, sulfonated polysulfone, polyethersulfone, sulfonated polyethersulfone, chlorinated polyethylene, polypropylene, polyolefin, polyvinyl alcohol, Examples thereof include organic materials such as polymethyl methacrylate, polyvinylidene fluoride, and polytetrafluoroethylene, metals such as stainless steel, and inorganic materials such as ceramic. The material of the ultrafiltration membrane may be appropriately selected in view of the properties of the hydrolyzate and the running cost, but is preferably an organic material, such as chlorinated polyethylene, polypropylene, polyvinylidene fluoride, polysulfone, and polyethersulfone. More preferably. Specifically, G-5 type, G-10 type, G-20 type, G-50 type, PW type, HWS UF type from DESAL, HFM-180, HFM-183, HFM-251 from KOCH, HFM-300, HFM-116, HFM-183, HFM-300, HFK-131, HFK-328, MPT-U20, MPS-U20P, MPS-U20S, SPE1 from Sinder, SPE3, SPE5, SPE10, SPE30, SPV5 SPV50, SOW30, Asahi Kasei Microza (registered trademark) UF series molecular weight equivalent to 3000 to 100,000, NTR7410, NTR7450 manufactured by Nitto Denko Corporation, and the like.

  The apparatus for producing a sugar liquid of the present invention is an enzyme saccharification tank for obtaining a enzymatic saccharified liquid by hydrolyzing a pretreated product of cellulose-containing biomass with a saccharifying enzyme, and the enzyme saccharified liquid is a porous having an average pore size of 0.25 μm or less. Membrane separation tank for obtaining a sugar solution as a membrane permeation fraction through a cross-flow filtration through a porous microfiltration membrane, and a sugar solution obtained in the membrane separation tank using a nanofiltration membrane and / or a reverse osmosis membrane A sugar solution purification unit that obtains a sugar solution that has been filtered and purified as a membrane-impermeable fraction.

  The apparatus for producing a sugar liquid of the present invention can be used for carrying out the above-described method for producing a sugar liquid of the present invention. Specifically, the step (1) for obtaining an enzyme saccharified solution by adding a saccharifying enzyme to a pretreated product obtained by pretreating cellulose-containing biomass is an enzyme saccharification obtained in step (1) in an enzyme saccharification tank. The step (2) of obtaining a sugar solution as a membrane permeation fraction is obtained in step (2) in a membrane separation tank by passing the liquid through a porous microfiltration membrane having an average pore size of 0.25 μm or less and cross-flow filtration. The obtained sugar solution is filtered through a nanofiltration membrane and / or a reverse osmosis membrane, and the step (3) for obtaining a sugar solution purified as a membrane non-permeating fraction can be carried out in the sugar solution purification unit.

  The example of the manufacturing apparatus of the sugar liquid of this invention is shown in FIGS. The sugar liquid production apparatus of the present invention is not limited to these examples. Hereinafter, the sugar liquid production apparatus of the present invention will be described using an example of the sugar liquid production apparatus shown in FIGS.

  In the example of the sugar liquid production apparatus shown in FIG. 1, the enzyme saccharification tank 1 and the membrane separation tank 10 are connected to each other, and the membrane separation tank 10 and the sugar liquid purification unit 11 are connected by lines equipped with liquid feed pumps, respectively. ing. The enzyme saccharification tank 1 has a pretreatment product supply unit 17 for supplying a pretreatment product of cellulose-containing biomass and a saccharification enzyme supply unit 2 for supplying a saccharification enzyme.

  The membrane separation tank 10 has a viscometer 4 for measuring the viscosity of the enzyme saccharified solution in the tank. Thereby, the viscosity of the enzyme saccharified solution in the tank can be measured, and the MLSS concentration of the enzyme saccharified solution can be indirectly detected. Further, the membrane separation tank 10 is controlled so as to maintain the viscosity of the enzyme saccharified solution within a preset range by performing a hydration treatment or a drainage treatment or both treatments according to the measured viscosity value of the enzyme saccharified solution. And a hydration / drainage control unit 3. That is, when the upper limit value of the viscosity setting range is exceeded, the viscosity is kept within the setting range by performing water treatment from the water outlet 5 and / or discharging part of the enzyme saccharified solution from the outlet 6. Controlled to maintain. Here, the discharged enzyme saccharified solution is intermittently or continuously supplied to a solid-liquid separation means (not shown) such as a continuous centrifuge to remove solids and the like, and then again in the membrane separation tank 10 It is preferable to return to.

  The membrane separation tank 10 has a microfiltration membrane unit 8 provided with a porous microfiltration membrane having an average pore diameter of 0.25 μm or less in the tank. The enzyme saccharified solution is cross-flow filtered through a porous microfiltration membrane to obtain a sugar solution as a membrane permeation fraction. Further, preferably, as shown in FIG. 1, when performing cross-flow filtration with a porous microfiltration membrane, a diffuser tube 9 for aerating gas to the porous microfiltration membrane, and a rectifying plate for rectifying the liquid flow 7 The rectifying plate 7 is installed so that the flow of the enzyme saccharified solution is generated in the opposite direction on the front and back of the rectifying plate and the solution circulates.

  The sugar solution purification unit 11 shown in FIG. 1 has a membrane unit including a nanofiltration membrane or a reverse osmosis membrane, or both. The sugar solution sent from the membrane separation tank 10 can be filtered through these membranes to obtain a sugar solution purified as a membrane non-permeating fraction.

  In the example of the sugar liquid production apparatus shown in FIG. 2, a pH meter 13 for measuring the pH of the liquid in the tank is added to the enzyme saccharification tank 1, and an acid is added to the tank to lower the pH of the liquid. An acid supply unit 12 is provided. The pH meter 13 and the acid supply unit 12 may be linked to each other so as to control the pH to be equal to or lower than a preset upper limit value. Further, a solid-liquid separation means 14 is provided in a line connecting the enzyme saccharification tank 1 and the membrane separation tank 10. As the solid-liquid separation means 14, those capable of removing the solid component intermittently or continuously can be used, but those which are continuous are preferred, and a continuous centrifugal separator is particularly preferred. As the continuous centrifugal separator, for example, a screw decanter type is preferable because of easy scale-up. Further, a separation plate type (DeLaval type) may be used. In the case of using a separation plate type, since fiber components may stay in the apparatus and the long-term operability of the apparatus may be hindered, it is more preferable to perform in combination with screw decanter type centrifugation as a previous step.

  The example of the sugar liquid production apparatus shown in FIG. 3 has an enzyme saccharification / membrane separation tank 16 in which the enzyme saccharification tank 1 and the membrane separation tank 10 are integrated. In the enzyme saccharification / membrane separation tank 16, the saccharification enzyme supply unit 2, the pretreatment product supply unit 17, the microfiltration membrane unit 8, the current plate 7, and the air diffuser 9 are provided in the same manner as the example of the apparatus shown in FIG. 1 or 2. Is provided. Moreover, in order to measure pH in the enzyme saccharification / membrane separation tank 16 and adjust pH like the example of the apparatus shown in FIG.

  Further, in the example of the sugar solution production apparatus shown in FIG. 3, the enzyme saccharification solution is controlled in the enzyme saccharification / membrane separation tank 16 so as to maintain the viscosity of the enzyme saccharification solution within a preset range. A circulation line for circulation via the solid-liquid separation means 14 is provided. The liquid feed pump on this circulation line is controlled by the solid-liquid separation control unit 15 and is operated when the viscosity measurement value of the enzyme saccharified liquid measured by the viscometer 4 exceeds the upper limit value of the setting range. The enzyme saccharified solution is subjected to solid-liquid separation by the solid-liquid separation means 14 in the circulation line. Furthermore, the enzyme saccharification / membrane separation tank 16 has a water inlet 5 for performing a water treatment in order to keep the volume of the enzyme saccharified solution in the tank constant. The opening and closing of the water spout 5 may be controlled in conjunction with a liquid meter (not shown) installed in the enzyme saccharification / membrane separation tank 16.

  In the example of the sugar liquid production apparatus shown in FIG. 4, an ultrafiltration membrane unit 19 and an ultrafiltration membrane supply tank 18 are further provided between the membrane separation tank 10 and the sugar liquid purification unit 11. The saccharification enzyme can be removed by filtering the sugar solution obtained by cross-flow filtration with the microfiltration membrane unit 8 through the ultrafiltration membrane unit 19. The membrane non-permeate fraction of the ultrafiltration membrane unit 19 is returned to the saccharification enzyme supply unit 2 in the enzyme saccharification tank 1 via the recovered enzyme return line 20 and used for the step of performing enzymatic saccharification again. it can.

  In the example of the sugar liquid production apparatus shown in FIG. 4, the microfiltration membrane unit 8 exists outside the membrane separation tank 10, and the enzyme saccharified solution is supplied to the microfiltration membrane unit 9 by pumping (not shown). Cross flow filtration can be performed by external circulation. The microfiltration membrane unit 8 in this case is preferably a hollow fiber type or a tubular type since solid content may be deposited on the spacer portion if it is a spiral type. In particular, in the case of the hollow fiber type, since the fiber component of the cellulose-containing biomass may be wound around the yarn, it is preferable to provide the solid-liquid separation means 14 at the front stage portion of the membrane separation tank 10.

  Furthermore, in the example of the sugar solution production apparatus shown in FIG. 4, the sugar solution obtained by filtering through the ultrafiltration membrane unit 19 is sent to the sugar concentration tank 21. The sugar solution sent to the sugar concentration tank 21 was sent to a sugar solution purification unit (nanofiltration membrane and / or reverse osmosis membrane) 11, filtered through these membranes, and purified as a membrane non-permeate fraction. A sugar solution can be obtained. Here, the refined sugar solution can be concentrated by returning the refined sugar solution to the sugar concentration tank 21 again.

  Hereinafter, the method for producing a sugar liquid of the present invention will be described with reference to examples in order to explain in more detail. However, the present invention is not limited to these examples.

(Reference Example 1) Monosaccharide concentration measurement method Monosaccharide concentrations (glucose concentration, xylose concentration) contained in the sugar solutions obtained in each Example and Comparative Example were analyzed by HPLC under the conditions shown below. Quantified by comparison with.

Column: Luna NH2 (Phenomenex)
Mobile phase: Ultrapure water: Acetonitrile = 25: 75 (flow rate 0.6 mL / min)
Reaction solution: None Detection method: RI (differential refractive index)
Temperature: 30 ° C.

(Reference Example 2) Method for Measuring Concentration of Fermentation Inhibitory Substance Among fermentation inhibition substances contained in sugar solution, furan fermentation inhibition substances (HMF, furfural) and phenolic fermentation inhibition substances (vanillin, acetovanillin, syringic acid, levulin) The concentration of the acid, 4-hydroxybenzoic acid) was analyzed by HPLC under the conditions shown below, and quantified by comparison with a standard product.

Column: Synergi HideRP 4.6 mm × 250 mm (Phenomenex)
Mobile phase: _0.1% acetonitrile H 3 PO ₄ (flow rate 1.0 mL / min)
Detection method: UV (283 nm)
Temperature: 40 ° C.

  Among the fermentation inhibitory substances contained in the sugar solution, organic acids (acetic acid and formic acid) were analyzed by HPLC under the conditions shown below, and quantified by comparison with a standard product.

Column: Shim-Pack SPR-H and Shim-Pack SCR101H (manufactured by Shimadzu Corporation) Mobile phase: 5 mM p-toluenesulfonic acid (flow rate 0.8 mL / min)
Reaction solution: 5 mM p-toluenesulfonic acid, 20 mM Bistris, 0.1 mM EDTA · 2Na (flow rate 0.8 mL / min)
Detection method: electrical conductivity Temperature: 45 ° C.

(Reference Example 3) Method for Measuring Turbidity The turbidity of the sugar solution was quantified using an indoor advanced turbidimeter (2100N) manufactured by HACH. Since this turbidimeter can only measure turbidity of 1000 NTU or less, the sugar solution was diluted with distilled water as necessary and measured.

(Reference example 4) Measuring method of solid content The solid content in the sugar liquid is measured by applying 10 mL of the sugar liquid as a measurement object using a moisture content meter (Infrared Moisture Meter FD720). (Weight%) was determined, and the water content was determined as a value subtracted from 100%.

(Reference Example 5) Measuring Method of MLSS Concentration The MLSS concentration of the sugar solution was measured according to JIS K0102 14.1 (2008). Glass fiber filter paper (GS-25 manufactured by ADVANTEC) was heated at 105 ° C. for 2 hours, and the weight (weight a) of the glass fiber filter paper was measured. The dried glass fiber filter paper was set in a filter holder for filtration (ADVANTEC KP-47S), and the sample solution VmL (2 to 10 mL) was subjected to suction filtration. The glass fiber filter paper was again heated at 105 ° C. for 2 hours, then the weight (weight b) was measured, and the MLSS concentration was calculated by the following formula 3.

    MLSS concentration [mg / L] = (b−a) [mg] / V [mL] × 1000 (formula 3).

(Reference Example 6) Viscosity Measurement Method The viscosity of the sugar solution was measured using a rotating cylindrical viscometer (Viscotester VT-03F, manufactured by Rion Co., Ltd.) in a state where the precipitate was sufficiently stirred and suspended. .

Example 1
In step (1), rice straw was used as the cellulose-containing biomass, which was hydrothermally treated to obtain an enzyme saccharified solution as follows. First, rice straw was soaked in water and subjected to autoclaving (manufactured by Nitto Koatsu) at 200 ° C. for 15 minutes while stirring. After the treatment, the mixture was allowed to stand for 1 hour, and then the hot water soluble component of the supernatant component was used as a hydrothermal treatment liquid (pretreated product). Next, Trichoderma cellulase (Sigma-Aldrich Japan) and Novozyme 188 (Aspergillus niger-derived β-glucosidase preparation, Sigma-Aldrich Japan) are added to the hydrothermal treatment solution as saccharifying enzymes, and the mixture is stirred and mixed at 50 ° C. for 1 day. Then, a hydrolysis reaction was performed to obtain a hydrothermal treatment saccharified solution (enzymatic saccharified solution). The concentrations of the monosaccharide and the fermentation inhibitor contained in the obtained hydrothermal saccharified solution were as shown in Tables 1 and 2, respectively. The turbidity of the hydrothermal saccharified solution was 12000 NTU. The solid content was 6.0%.

  Next, as step (2), an equal amount of water is added to 1 L of the hydrothermal saccharified saccharified solution obtained in step (1) to make 2 L, and the turbidity is set to 6000 NTU. The membrane was fed to a microfiltration membrane and subjected to cross flow filtration, and a 1.8 L sugar solution was recovered from the membrane permeation side by a constant filtration flow rate operation using a peristaltic pump. Here, the membrane surface linear velocity of the cross flow filtration was set to 30 cm / second, and the microfiltration membrane was set in a flat membrane test apparatus, and filtration was performed under the condition of a membrane permeation flux of 0.1 m / day. As the porous microfiltration membrane, a polyvinylidene fluoride flat membrane having a nominal average pore size of 0.08 μm used in a microfiltration membrane “Membray” (registered trademark) TMR140 manufactured by Toray Industries, Inc. was used. The turbidity of the sugar solution obtained in the above step (2) was 1 NTU or less, and the solid content was 2.4%.

  As step (3), 1.8 L of the sugar solution obtained in the above step (2) was supplied to the nanofiltration membrane at a pressure of 3 MPa at a temperature of 25 degrees and subjected to cross flow filtration. The purified sugar solution was collected from the membrane non-permeating side, and the permeated water containing the fermentation inhibitor was removed from the membrane permeating side to obtain 0.225 L of purified sugar solution. By this operation, the sugar solution obtained in the step (2) is concentrated 8 times, and is concentrated 4 times in terms of the concentration of the stock solution before the addition in the step (2). Here, as a nanofiltration membrane, a flat membrane of “UTC-60” used in a nanofiltration membrane “SU-610” manufactured by Toray Industries, Inc. was cut out and used. The processing time required at this time was 6 hours. The concentrations of the monosaccharide and the fermentation inhibitor contained in the purified sugar solution obtained as a membrane-impermeable component are as shown in Tables 3 and 4, respectively.

(Comparative Example 1)
After adding an equal amount of water to 1 L of the hydrothermal saccharified liquid (enzymatic saccharified liquid) obtained in step (1) of Example 1 to make 2 L, as a step (2), instead of cross-flow filtration, a filter press ( Filtration was performed at a maximum pressure of 0.2 MPa and a pressure of 0.5 MPa using MO-4) manufactured by Iwata Sangyo.

  When filtration was performed with a filter press using a Yuasa microfiltration membrane (average pore diameter of 1.0 μm) as a porous microfiltration membrane, only about 50 mL of filtrate could be recovered in the press-in treatment for 1 hour. The operation was canceled.

  Moreover, when the sugar solution obtained as a filtrate was filtered with a filter press using a Yuasa microfiltration membrane (average pore diameter: 0.1 μm), the filtrate was recovered only about 20 mL in the press-in treatment for 1 hour. I couldn't do it and stopped processing.

(Comparative Example 2)
After adding an equal amount of water to 1 L of the hydrothermally treated saccharified solution obtained in the step (1) of Example 1 to make 2 L, the turbidity is 6000 NTU, and as the step (2), a non-woven membrane is used instead of the porous microfiltration membrane. Was supplied to a nonwoven fabric membrane at a pressure of 30 kPa at a temperature of 25 ° C. and subjected to cross flow filtration, and a 1.8 L sugar solution was recovered from the membrane permeation side. Here, the membrane surface linear velocity at the time of crossflow filtration was set to 30 cm / second, and filtration was performed under the condition of a membrane permeation flux of 0.1 m / day. As the nonwoven fabric membrane, a polyester nonwoven fabric membrane M-2080-3T (thickness 0.36 mm, air permeability 50 cc / cm ² · sec) used in Toray Industries, Ltd. microfiltration membrane “Axter” (registered trademark), G -2260-3S (thickness 0.62 mm, air permeability 11 cc / cm ² · sec) and polypropylene non-woven fabric FC305 (made by Iwata Sangyo, thickness 0.80 mm, air permeability 5.0 cc / cm ² · sec) did. Even when any nonwoven membrane was used, a 1.8 L sugar solution could be recovered, but the turbidity was as shown in Table 5.

  As step (3), 1.8 L of the sugar solution permeated through these nonwoven fabric membranes was supplied to the nanofiltration membrane in the same manner as in Example 1 at a pressure of 3 MPa and a temperature of 25 degrees, and subjected to cross flow filtration. In either case, however, the membrane was blocked within 10 minutes and could not be filtered.

(Comparative Example 3)
An equal amount of water is added to 1 L of the hydrothermally treated saccharified solution obtained in step (1) of Example 1 to make 2 L, and the turbidity is set to 6000 NTU. Then, in step (2), weaving is performed instead of the porous microfiltration membrane. The cloth membrane was supplied to the woven fabric membrane at a pressure of 30 kPa at a temperature of 25 ° C. and subjected to cross flow filtration, and a 16 L sugar solution was recovered from the membrane permeation side. Here, the membrane surface linear velocity at the time of crossflow filtration was set to 30 cm / second, and filtration was performed under the condition of a membrane permeation flux of 0.1 m / day. As the woven fabric film, Iwata Sangyo woven fabric T2731C (polyester, double weave, thickness 0.59 mm, air permeability 1.67 cc / cm ² · sec), T1005C (polyester, double weave, thickness 0.56 mm) , Air permeability 1.2 cc / cm ² · sec) and TF7104C (made of polyester, weft weave, thickness 0.70 mm, air permeability 0.5 cc / cm ² · sec) were cut out and used. Even when any woven fabric membrane was used, a 1.8 L sugar solution could be recovered. However, in any woven fabric membrane, bubbles were generated on the membrane permeation side, and clogging was remarkable. The turbidity was as shown in Table 6, respectively.

  As step (3), 1.5 L of the sugar solution that has passed through these woven fabric membranes is supplied to the nanofiltration membrane in the same manner as in Example 1 at a pressure of 3 MPa and a temperature of 25 degrees, and subjected to cross flow filtration. It was. In either case, however, the membrane was blocked within 10 minutes and could not be filtered.

(Example 2)
An equal amount of water is added to 1 L of the hydrothermal saccharified solution 1 L obtained in the step (1) of Example 1 to make 2 L, and the turbidity is set to 6000 NTU. Then, as the step (2), the pressure is 30 kPa and the temperature is 25 ° C. The solution was supplied to porous microfiltration membranes having different average pore diameters and subjected to cross flow filtration, and 1.8 L of a sugar solution was recovered from the membrane permeation side. Here, the membrane surface linear velocity at the time of cross-flow filtration is set to 30 cm / second, and filtration is performed by setting a microfiltration membrane under the conditions of 0.1 m / day and membrane permeation flux 0.25 m / day. went. Porous microfiltration membranes include “Isopore” (registered trademark) VMTP (average pore diameter 0.05 μm, polycarbonate) manufactured by Millipore, GE EW series (average pore diameter: 0.04 μm, manufactured by Polysulfone), Yuasa Co., Ltd. MF-10 (average pore diameter of 0.1 μm), MF-20 (average pore diameter of 0.2 μm), “Durapore” (registered trademark) GVWP manufactured by Millipore A microfiltration membrane was cut out from each (average pore diameter 0.22 μm) and used. As in Example 1, at 0.1 m / day, a 1.8 L sugar solution could be recovered without membrane clogging in any case. Further, under the condition of 0.25 m / day, when the permeation of 1.6 L was performed for two types of MF-20 (average pore diameter 0.2 μm) and GVWP (average pore diameter 0.22 μm), the membrane permeation flux was 0. Although it decreased to 2 m / day, it was finally possible to recover 1.8 L, and in any case other than these two types, a 1.8 L sugar solution could be recovered without membrane clogging.

  As step (3), 1.6 L of the sugar solution obtained in the above step (2) was supplied to the nanofiltration membrane at a pressure of 3 MPa and a temperature of 25 ° C. in the same manner as in Example 1 to perform cross-flow filtration. I let you. While collecting the purified sugar solution from the membrane non-permeating side, the permeated water containing the fermentation inhibitor was removed from the membrane permeating side to obtain 2 L of purified sugar solution. By this operation, the sugar solution obtained in the step (2) is concentrated 8 times, and is concentrated 4 times in terms of the concentration of the stock solution before the addition in the step (2). The processing time required at this time was 10 hours as in Example 1. The concentrations of the monosaccharide and the fermentation inhibitor contained in the purified sugar solution obtained as a membrane-impermeable component were as shown in Tables 7 and 8 as in Example 1.

(Comparative Example 4)
An equal amount of water is added to 1 L of the hydrothermal saccharified solution 1 L obtained in step (1) of Example 1 to make 2 L, and the turbidity is set to 6000 NTU. Then, as step (2), porous microfiltration having different average pore diameters is performed. The membrane was supplied with a pressure of 30 kPa at a temperature of 25 ° C. and subjected to cross flow filtration, and an attempt was made to recover a 1.8 L sugar solution from the membrane permeation side. Here, the membrane surface linear velocity at the time of cross-flow filtration was set to 30 cm / second, and filtration was performed by setting each microfiltration membrane under the condition of membrane permeation flux of 0.1 m / day. As the porous microfiltration membrane, UF-40 (average pore size 0.4 μm), MF-60 (average pore size 0.6 μm), MF of the microfiltration membrane “YUMICRON Membrane Filter” (registered trademark) manufactured by Yuasa Co., Ltd. Microfiltration membranes were cut out from -90 (average pore size 0.9 μm), MF-250 (average pore size 2.5 μm), and “Durapore” (registered trademark) HVLP (average pore size 0.45 μm) manufactured by Millipore. used. In any case, the membrane was blocked during the membrane permeation flux of 0.1 m / day, and the sugar solution could not be recovered. Membrane permeation flux 0.1 m / day (in the case of Example 1, normal processing time: 30 hours) Filtration speed cannot be maintained, bubbles are generated, and the actual filtration flow rate is halved (membrane permeation flux) When the time of 0.05 m / day was measured as the membrane occlusion time, the results shown in Table 9 were obtained. In the case of the membrane of MF-40 (average pore diameter 0.4 μm), the membrane was blocked without reaching the target 1.8 L, but a 1.6 L sugar solution was obtained.

  As step (3), 1.6 L of the sugar solution obtained in the case of MF-40 is supplied to the nanofiltration membrane at a pressure of 3 MPa and a temperature of 25 degrees in the same manner as in Example 1 to perform cross-flow filtration. did. However, when 0.8 L was filtered in 3 hours, the membrane flux dropped sharply, making filtration difficult, and the filtration was stopped. The concentration of the monosaccharide and the fermentation inhibitor in the non-permeate side sugar solution after 0.8 L filtration was measured (Tables 10 and 11), but the purification and concentration were insufficient.

(Comparative Example 5)
After adding an equal amount of water to 1 L of the hydrothermal saccharified solution 1 L obtained in the step (1) of Example 1 to make 2 L, the turbidity was set to 6000 NTU, as a step (2), instead of the porous microfiltration membrane, At a pressure of 30 kPa, the mixture was supplied to an ultrafiltration membrane at a temperature of 25 ° C. and subjected to cross-flow filtration. Here, the membrane surface linear velocity at the time of crossflow filtration was set to 30 cm / second, and filtration was performed by setting an ultrafiltration membrane under the condition of a membrane permeation flux of 0.1 m / day. As ultrafiltration membranes, KOCH ultrafiltration membranes HFM-300 (fractionated molecular weight: 100,000, made of polyvinylidene fluoride) and HFK-131 (fractionated molecular weight: 10,000, made of polyethersulfone) were cut out, respectively. used. In any of the ultrafiltration membranes, the filtration rate could not be maintained under the filtration conditions of a membrane permeation flux of 0.1 m / day (in the case of Example 1, normal processing time: 30 hours). When the time when the actual filtration flow rate became half (membrane permeation flux 0.05 m / day) was measured as the membrane occlusion time, the results shown in Table 12 were obtained.

(Reference Example 5) Examination of the cause of membrane occlusion (1)
The hydrothermal saccharified solution obtained in step (1) of Example 1 was ultracentrifugated at 10,000 G for 30 minutes, and then using a dynamic light scattering method (manufactured by Otsuka Electronics, zeta potential / particle size measurement system ELSZ-2). The particle size distribution in the liquid was measured. The turbidity of the liquid obtained by this ultracentrifugation treatment was 300 NTU. As a result, as shown in FIG. 5, a remarkable particle peak was observed between the particle diameters of 0.24 μm and 0.48 μm.

  When this particle component is filtered using a porous microfiltration membrane having a mean pore diameter of greater than 0.25 μm or a non-porous microfiltration membrane (woven fabric membrane, nonwoven fabric membrane, etc.) in step (2), or thereafter In step (3), it was presumed that this was a cause of clogging when filtering with a nanofiltration membrane or a reverse osmosis membrane. That is, in the step (2) of the method for producing a sugar liquid of the present invention, it has been found that it is important to use a porous microfiltration membrane having an average pore diameter of 0.25 μm or less smaller than the particle component. .

(Reference Example 6) Examination of the cause of membrane occlusion (2)
1 L of the liquid obtained by ultracentrifugation in Reference Example 5 was supplied to the nanofiltration membrane at a pressure of 3 MPa at a pressure of 3 MPa in the same manner as in Step (3) of Example 1, and subjected to cross flow filtration. However, when 0.25 L was filtered in 1 hour, the membrane flux dropped sharply and filtration became difficult, and the filtration was stopped. When the membrane after filtration was observed with a scanning electron microscope (Hitachi S-4800), it was found that the particle component adhered to the entire membrane as shown in FIG. Further, the adhering particle component was measured with a SEM-EDX detector attached to an electron microscope, and as a result, was found to be silica (silicon dioxide) particles.

(Example 3)
In step (2) of Example 1, the amount of water was changed to examine the membrane filterability. When 0.5 L of RO water is added to 1 L of the hydrothermal treatment saccharified solution obtained in step (1) of Example 1 (hydrolysis treatment A), when 1 L of RO water is added (hydrolysis treatment B: The same as in Example 1) When 4 L of RO water is added (Hydrolysis C), and when 9 L of RO water is added (Hydrolysis D), the pressure of 30 kPa is the same as in Example 1. Then, it is supplied to a porous microfiltration membrane at a temperature of 25 ° C. and subjected to cross flow filtration until the membrane non-permeate water which is a dead volume of the apparatus becomes 0.2 L by constant filtration flow rate operation using a peristaltic pump from the membrane permeation side. The sugar solution was collected. Here, the membrane surface linear velocity at the time of cross-flow filtration is set to 30 cm / second, and the membrane permeation flux is 0.1 m / day (same as Example 1) and 0.25 m / day under the respective filtration flow rate conditions. The microfiltration membrane was set in a flat membrane test apparatus and filtered. As the microfiltration membrane, a polyvinylidene fluoride flat membrane having a nominal average pore size of 0.08 μm used in a microfiltration membrane “Membray TMR140” (registered trademark) manufactured by Toray Industries, Inc. was used.

  Table 13 summarizes the results for each membrane permeation flux (filtration flow rate conditions) in the case of the hydrotreatments A to D. “◯” in the table indicates that filtration was possible without a change in flow rate, and “x” indicates that filtration was not possible on the way. “Δ” indicates that the flow rate could not be kept constant, but could be filtered until the membrane non-permeation side reached 0.2 L.

  As step (3), each sugar solution obtained under the filtration conditions of membrane permeation flux 0.1 m / day in the hydrotreatments A to D was applied to a nanofiltration membrane “SU- A flat membrane of “UTC-60” used in 610 ”was cut out and set, and the flow was supplied to the nanofiltration membrane at a pressure of 3 MPa at a temperature of 25 ° C. and subjected to cross flow filtration. Filtration was performed such that the sugar concentration was 4 times that of the hydrothermal saccharified solution before the hydrotreatment in step (2). Tables 14 and 15 show the sugar concentration, liquid amount, and fermentation inhibitor concentration of the sugar solution (concentrated solution) on the membrane non-permeation side in each hydrolysis treatment. The sugar concentration did not change for glucose or xylose, but it was found that the amount of liquid obtained by the hydrotreatment was different and the yield of sugar was improved. Further, it was found that the fermentation inhibitor concentration in the sugar solution decreases when the amount of water treatment is large.

Example 4
In the step (2) as in Example 3, the hydrothermal saccharified solution obtained in the step (1) of Example 1 was centrifuged at 3000 G for 1 minute to remove the precipitate. Membrane filterability was compared by changing the amount of water added. The solid content of the hydrothermal saccharified solution after centrifugation was 5.7%. When 0.5 L of RO water is added to 1 L of hydrothermally treated saccharified solution after centrifugation (hydrolysis E), when 1 L of RO water is added (hydrolysis F: the same as in Example 1), 4 L Filtration by the porous microfiltration membrane of the step (2) in the same manner as in Example 3 with respect to the four conditions when RO water is added (hydrolysis G) and 9 L of RO water is added (hydrolysis H) Went.

  Table 16 summarizes the results of the membrane permeation fluxes (filtration flow rate conditions) in the case of the hydrolysis treatments E to H. “◯”, “×”, and “Δ” in the table are the same as those in the third embodiment. Compared with Example 3 (Table 13), the solid content can be removed in advance by carrying out the centrifugation step before step 2, so that the improvement of membrane filtration performance by the hydration treatment became more remarkable.

  As a process (3), after adjusting each sugar solution obtained by the filtration conditions of the membrane permeation flux 0.1m / day by hydroprocessing EH to pH3.0 with 5% sulfuric acid aqueous solution, Toray Industries, Inc. make A flat membrane of the ultra-low pressure reverse osmosis membrane “SUL-G10” was cut out and set, supplied to the reverse osmosis membrane at a pressure of 4 MPa at a temperature of 25 ° C., and subjected to cross flow filtration. Filtration was performed such that the sugar concentration was 4 times that of the hydrothermal saccharified solution before the hydrotreatment in step (2). Tables 17 and 18 show the sugar concentration, the liquid amount, and the fermentation inhibitor concentration of the sugar solution (concentrated solution) on the membrane non-permeation side at the time of each hydrolysis treatment. The sugar concentration did not change for glucose or xylose, but it was found that the amount of liquid obtained by the hydrotreatment was different and the yield of sugar was improved. Further, it was found that the fermentation inhibitor concentration in the sugar solution decreases when the amount of water treatment is large.

(Reference Example 7) Ethanol Fermentation with Yeast In Comparative Example 7 and Example 5, ethanol fermentation with a yeast strain (OC2, Saccharomyces cerevisiae, wine yeast) was performed as follows, and the resulting sugar solution was evaluated. It was.

The fermentation medium was prepared with the following composition, and the filter sterilized (Millipore, Stericup 0.22 μm) was used for fermentation.
<Fermentation medium>
Glucose: 30g / L
Dropout MX: 3.8 g / L
Yeast NTbase: 1.7 g / L.

  Glucose test Wako (Wako Pure Chemical Industries) was used for quantitative determination of glucose concentration. The amount of ethanol produced in each culture solution was determined by gas chromatography (Shimadzu GC-2010 capillary GC TC-1 (GL science) 15 meter L. * 0.53 mm ID, df 1.5 μm). And measured by a flame ionization detector.

  Yeast (OC2 strain) was cultured in a test tube with 5 ml of the above fermentation medium (preculture medium) with shaking overnight (preculture). The yeast was recovered from the preculture solution by centrifugation and washed well with 15 mL of sterilized water. The washed yeast was inoculated into 100 ml of the above fermentation medium and cultured with shaking in a 500 ml Sakaguchi flask for 24 hours (main culture).

(Comparative Example 6)
After concentrating the hydrothermal saccharified solution 1L obtained in the step (1) of Example 1 with an evaporator until it becomes 0.25L, a fermentation medium is prepared using the obtained distilled concentrated solution as a glucose source. As described in Reference Example 7, pre-culture and main culture were performed, and ethanol fermentation was performed. In the pre-culture, a reagent monosaccharide was used, and a distilled concentrate was used only during the main culture. Table 19 shows the glucose consumption and the ethanol accumulation concentration as a result of the above ethanol fermentation.

(Example 5)
A fermentation medium was prepared using about 100 mL of each of the purified sugar solutions obtained under the conditions of the hydrotreatments A to D of Example 3 and the reagent glucose as a glucose source as a comparative control, as described in Reference Example 7. Ethanol fermentation was performed by pre-culture and main culture. In the pre-culture, a reagent monosaccharide was used, and each purified sugar solution was used only during the main culture.

  Table 20 shows the glucose consumption and the ethanol accumulation concentration as a result of the above ethanol fermentation. By filtering with a porous microfiltration membrane and a nanofiltration membrane as in Example 3, fermentation inhibition was suppressed and ethanol accumulation concentration was improved as compared with the case of the distilled concentrate of Comparative Example 7.

(Example 6)
Using the hydrothermal saccharified solution obtained in the step (1) of Example 1, enzyme saccharified solutions having different MLSS concentrations were prepared. Hydrothermally treated saccharified solution 10L obtained in step (1) of Example 1 (hereinafter referred to as stock solution), 1L of hydrothermally processed saccharified solution 1L of RO water 1 L in total (hereinafter referred to as hydrolyzed solution), hydrothermally processed saccharified solution The liquid was centrifuged at 1500 G for 2 minutes to remove the precipitate, and 10 L (hereinafter referred to as “centrifugation liquid”). The hydrothermal saccharified liquid was centrifuged at 1500 G for 2 minutes to remove the precipitate to 1 L. A total of 2 L of liquid (hereinafter referred to as centrifugal hydrolyzed liquid) prepared by 1 L of water was prepared. The results of measuring the respective MLSS concentrations and viscosities are shown in Table 21. From this result, it was found that there is a certain positive correlation between the MLSS concentration and the viscosity.

  As the step (2), two types of the stock solution and the centrifugal treatment solution are supplied to the porous microfiltration membrane at a temperature of 25 ° C. at a pressure of 72 kPa, and intermittent operation with a constant filtration flow rate using a peristaltic pump from the membrane permeation side (9 The cross-flow filtration was performed while measuring the filtration side pressure in 1 minute stop). Here, the membrane surface linear velocity at the time of cross-flow filtration was set to 30 cm / second, and filtration was performed by setting each microfiltration membrane under the filtration condition of membrane permeation flux of 0.12 m / day. As the porous microfiltration membrane, a flat membrane made of polyvinylidene fluoride having a nominal average pore diameter of 0.08 μm used in the microfiltration membrane “Membray” (registered trademark) TMR140 manufactured by Toray Industries, Inc. as in Example 1. Cut out and used.

  In the two types of filtration of the stock solution and the centrifugally treated solution, 200 mL each of the membrane non-permeate side solution at the time when the MLSS concentration reached 20000 mg / L, 30000 mg / L, 40000 mg / L, and 50000 mg / L was collected. Filtration was continued continuously while keeping the MLSS concentration constant while adding an equal amount of water to each collected liquid filtration amount, and the pressure on the membrane permeation side was measured at the start of filtration and 1 hour after the start of filtration. The results are shown in Table 22.

  As a result, in both the undiluted solution and the centrifuged solution, when the MLSS concentration was high, the membrane permeation side pressure was low because there were many membrane clogging components. Also, the difference between the membrane permeation side pressure at the start of filtration and the membrane permeation side pressure after continuous filtration for 1 hour while adding water equal to the membrane permeation amount while maintaining the MLSS concentration constant. When the MLSS concentration was 40000 mg / L or less, no pressure difference occurred. However, when the MLSS concentration was 50000 mg / L, the filtration side pressure decreased by 15 kPa, that is, there was no sign of membrane clogging. It was seen. Therefore, it was found that in order to stably filter the membrane for a long period of time, it is preferable to filter while maintaining the MLSS concentration of the enzyme saccharified solution at 40000 mg / L or less.

(Example 7)
A hydrothermal saccharified solution (enzymatic saccharified solution) obtained in the step (1) of Example 1 was added with sulfuric acid and changed to pH 3.0, 4.0, 4.5, or a pH of 5.0, And using 5 types of enzyme saccharified liquids that were changed to pH 7.0 with an aqueous sodium hydroxide solution (pH change before filtration), as step (2), it was supplied to the porous microfiltration membrane as in Example 1. Then, each sugar solution was recovered by cross-flow filtration.

  As step (3), each sugar solution was cut out and set as a flat membrane of “UTC-60” used in a nanofiltration membrane “SU-610” manufactured by Toray Industries, Ltd. as in Example 1. The pressure was supplied to the nanofiltration membrane at an operating pressure of 3 MPa and a temperature of 25 ° C., followed by cross-flow filtration. Filtration was performed so that the sugar concentration was 4 times that of the hydrothermal saccharified solution. Table 23 shows the membrane permeation flux at the point of 4 times.

  As a result, when the pH of the enzyme saccharified solution is reduced to acidic and cross-flow filtered with a microfiltration membrane, the membrane permeation flux at the time of filtration using the nanofiltration membrane in step (3) is increased, and the sugar solution It was found that the long-term drivability in concentration was improved.

  On the other hand, the hydrothermal saccharified solution (pH 5.0) obtained in the step (1) of Example 1 was subjected to cross flow filtration with a porous microfiltration membrane in the same manner as in the step (2) of Example 1, and then sulfuric acid or sodium hydroxide. Using the five sugar solutions (pH change after filtration) in which the solution was added to change the pH to 3.0, 4.0, 4.5, 5.0 (unadjusted), 7.0, the step ( 3) As in Example 1, each sugar solution was cut and set as a flat membrane of “UTC-60”, and supplied to the nanofiltration membrane at an operating pressure of 3 MPa at a temperature of 25 ° C. Cross-flow filtration was performed to obtain a sugar concentration of 4 times. Table 24 shows the membrane permeation flux at the point of 4 times.

  As a result of the above, comparing the results in Table 23 (pH change before filtration) with the same pH and the results in Table 24 (pH change after filtration), after performing cross-flow filtration using the microfiltration membrane in step (2) Compared with changing the pH of the enzyme saccharified solution, the cross-flow filtration process using the porous microfiltration membrane in the step (2) after changing the pH of the enzyme saccharified solution is more effective in the step (3) It has been found that the long-term operability of the membrane is improved in the concentration of the sugar solution using the filtration membrane.

  Furthermore, the fermentation inhibitor in the sugar solution obtained in the step (3) in the case of performing the cross-flow filtration treatment with the microfiltration membrane in the step (2) after changing the pH of the enzyme saccharified solution (Table 23) Table 25 shows the component concentrations. From this result, it was found that the concentration of organic acids such as formic acid and acetic acid can be lowered by changing the pH to acidic.

(Example 8)
In step (1), rice straw was used as the cellulose-containing biomass, and this was treated with ammonia (pretreatment) to obtain an enzyme saccharified solution. The rice straw was put into a small reactor (manufactured by pressure-resistant glass industry, 30 ml of TVS-N2) and cooled with liquid nitrogen. Ammonia gas was introduced into the reactor, and the rice straw was completely immersed in liquid ammonia. The reactor lid was closed and left at room temperature for about 15 minutes. Subsequently, it processed in the 150 degreeC oil bath for 1 hour. After the treatment, the reactor was taken out from the oil bath, and ammonia gas was immediately leaked in the fume hood. Then, the reactor was evacuated to 10 Pa with a vacuum pump to dry the treated ammonia. The ammonia-treated product (pre-treated product) was mixed with pure water and stirred so that the solid content concentration was 15% by weight, and then sulfuric acid was added to adjust the pH to around 5. Trichoderma cellulase (Sigma-Aldrich Japan) and Novozyme 188 (Aspergillus niger-derived β-glucosidase preparation, Sigma-Aldrich Japan) are added to this mixed solution as a saccharifying enzyme, and hydrolysis is performed while stirring and mixing at 50 ° C. for 1 day. Reaction was performed to obtain an ammonia-treated saccharified solution (enzyme saccharified solution).

  The enzyme saccharified solution obtained as described above is centrifuged (1500 G, 2 minutes), and as a step (2), cross-flow filtration using a porous microfiltration membrane is performed in the same manner as in Example 1, A sugar solution from which the solid content was separated and removed was obtained. This sugar solution was filtered using an ultrafiltration membrane having a molecular weight of 10,000 (GE PW series) until the amount of liquid on the non-permeation side became one-tenth of that before the treatment, and the saccharifying enzyme was removed from the sugar solution.

  To the sugar solution treated with the ultrafiltration membrane as described above, the pH is adjusted by adding sulfuric acid to change the pH to 3.0, as it is 5.0, and by adding sodium hydroxide aqueous solution. Prepare three kinds of substances changed to 7.0 (pH change before filtration), and perform cross-flow filtration using a porous microfiltration membrane in the same manner as in Example 1 for each sugar solution as step (2). went. For each of the three sugar solutions obtained, as in step (3), a flat membrane of “UTC-60” used in the nanofiltration membrane “SU-610” manufactured by Toray Industries, Inc. as in Example 1 was used. After cutting and setting, each sugar solution was supplied to the nanofiltration membrane at an operating pressure of 5 MPa, a temperature of 25 ° C., and subjected to cross flow filtration. Filtration was performed so that each sugar concentration was three times that of the sugar solution. Table 26 shows the membrane permeation flux at the time when the ratio was tripled.

  On the other hand, for the enzyme saccharified solution (pH 5.0) subjected to the ultrafiltration membrane treatment obtained as described above, as a step (2), a cloth using a porous microfiltration membrane as in Example 1 was used. After performing flow filtration, using the sugar solution (pH change after filtration) in which the pH was changed to 3.0 or 7.0 by adding sulfuric acid or sodium hydroxide solution to the obtained sugar solution, the step (3 ) As in Example 1, each sugar solution was cut and set in a flat membrane of “UTC-60”, and the operating pressure was 5 MPa and the temperature was supplied to the nanofiltration membrane at 25 ° C. Cross-flow filtration was performed so that the sugar concentration was tripled. The membrane permeation flux at the point of triple is shown in Table 27.

  As a result of the above, comparing the results of Table 26 and Table 27 having the same pH, even in the case of the enzyme saccharified solution subjected to the ammonia treatment as the pretreatment, the porosity of the step (2) after changing the pH. It has been found that long-term operability of the membrane is improved by performing the cross-flow filtration treatment with the microfiltration membrane in the concentration of the sugar solution using the nanofiltration membrane in the step (3).

  In this example, the pH was changed after the ultrafiltration membrane step, but the step of changing the pH and performing the microfiltration membrane treatment is particularly limited as long as the filtration is performed with a nanofiltration membrane and / or a reverse osmosis membrane. Not. In this embodiment, for example, it may be performed before the ultrafiltration membrane process. There may also be a separate step between the pH change and the microfiltration membrane treatment. For example, after changing the pH after enzymatic saccharification, a centrifugal separation treatment may be performed and a microfiltration membrane treatment may be performed. By setting it as the said process, it can be said that the density | concentration of the clogging substance to a microfiltration membrane or an ultrafiltration membrane is reduced, and the long-term operativity of a membrane improves.

DESCRIPTION OF SYMBOLS 1 Enzyme saccharification tank 2 Saccharification enzyme supply part 3 Hydrolysis / drainage control part 4 Viscometer 5 Suction port 6 Discharge port 7 Rectifying plate 8 Microfiltration membrane unit 9 Aeration tube 10 Membrane separation tank 11 Sugar solution purification part (nanofiltration membrane and (Or reverse osmosis membrane)
12 Acid supply unit 13 pH meter 14 Solid-liquid separation means 15 Solid-liquid separation control unit 16 Enzymatic saccharification / membrane separation tank 17 Pretreatment product supply unit 18 Ultrafiltration membrane supply tank 19 Ultrafiltration membrane unit 20 Recovered enzyme return line 21 Sugar concentration tank

Claims (8)

A method for producing a sugar solution from cellulose-containing biomass,
A step (1) of obtaining an enzyme saccharified solution by adding a saccharifying enzyme to a pretreated product obtained by pretreating cellulose-containing biomass;
The step (2), wherein the enzyme saccharified solution obtained in the step (1) is cross-flow filtered through a porous microfiltration membrane having an average pore size of 0.25 μm or less to obtain a sugar solution as a membrane permeation fraction,
A step (3) of obtaining a sugar solution purified as a membrane non-permeating fraction by filtering the sugar solution obtained in the step (2) through a nanofiltration membrane and / or a reverse osmosis membrane;
The manufacturing method of the sugar liquid containing this.   The method for producing a sugar liquid according to claim 1, wherein, in the step (2), the water treatment is performed before or during the crossflow filtration.   The process for producing a sugar solution according to claim 1 or 2, wherein in step (2), hydrolysis is performed so that the MLSS concentration of the enzyme saccharified solution is 40000 mg / L or less before or during crossflow filtration. Method.   The method for producing a sugar solution according to any one of claims 1 to 3, wherein, in step (2), the pH of the enzyme saccharified solution is changed and then cross-flow filtration is performed.   The method for producing a sugar liquid according to any one of claims 1 to 4, wherein in the step (1), the pretreatment is hydrothermal treatment, and a pretreated product containing a hot water-soluble component is used.   The manufacturing method of the sugar liquid of any one of Claim 1 to 5 whose solid content of the enzyme saccharified liquid of a process (1) is 0.1% or more and 10% or less.   7. The saccharified solution obtained in step (1) is subjected to at least one solid-liquid separation treatment selected from centrifugation, sedimentation separation and flotation separation as a pre-step of step (2). 2. A method for producing a sugar liquid according to item 1. An apparatus for producing a sugar solution from cellulose-containing biomass,
An enzyme saccharification tank having a pretreatment product supply unit for supplying a pretreatment product of cellulose-containing biomass and a saccharification enzyme supply unit for supplying a saccharification enzyme;
Viscometer for measuring the viscosity of the enzyme saccharified solution, a hydration / drainage control unit that performs hydration and / or drainage according to the measured viscosity value of the enzyme saccharified solution, and a porous precision with an average pore size of 0.25 μm or less A membrane separation tank having a filtration membrane, a cross-flow filtration of the enzyme saccharified solution obtained in the enzyme saccharification tank to obtain a sugar solution as a membrane permeation fraction, and a nanofiltration membrane and / or a reverse osmosis membrane, A sugar solution purification unit for filtering the sugar solution obtained in the membrane separation tank to obtain a sugar solution purified as a membrane non-permeating fraction,
An apparatus for producing a sugar solution comprising: