JP2011024545A - Method for producing saccharide from cellulose-containing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing a saccharide from a cellulose-containing material comprising calcium carbonate. <P>SOLUTION: The saccharide can efficiently be produced from the cellulose-containing material comprising the calcium carbonate by carrying out a step of bringing the cellulose-containing material comprising the calcium carbonate into contact with a cellulase having the optimum pH of 3-7 at pH7-11, and saccharifying the cellulose-containing material; a step of removing the calcium carbonate from the reaction solution by solid-liquid separation; and a step of adjusting the pH of the reaction solution after removing the calcium carbonate to 3-7, and saccharifying the cellulose-containing material with the cellulase at pH3-7. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for saccharifying a cellulose-containing material. In particular, the present invention relates to a technique for efficiently producing sugar from a cellulose-containing material containing calcium carbonate.

  In recent years, studies on effective use of biomass have been actively conducted due to an increase in environmental awareness. In particular, bioethanol produced using biomass as a raw material is expected to spread further, for example, as a gasoline substitute. For example, various studies have been conducted on a technique for producing sugar using biomass as a biomass and obtaining ethanol from the sugar by ethanol fermentation.

  When a cellulose-based material is used as a biomass material, lignocellulose containing lignin, cellulose from which lignin has been removed, and the like are generally used as the cellulose-based material. Examples of the lignocellulose raw material include wood such as hardwoods and conifers, agricultural residues such as straw and corn residues, and cellulose raw materials from which lignin has been removed to some extent include pulp. Wood, wheat straw, rice straw, corn, kenaf, etc. are known as the origin of cellulosic raw materials, but wood-based cellulose derived from wood is widely produced as pulp for papermaking, and biomass It is particularly attracting attention as a raw material.

  In particular, a sugar obtained by hydrolyzing a polysaccharide such as cellulose can be used in various chemical processes such as ethanol fermentation, and becomes a raw material for various chemical products. For this reason, it is important to develop a technology for saccharifying cellulosic materials represented by paper and pulp. In general, methods for hydrolyzing cellulosic materials to obtain sugars are as follows: (1) enzymatic saccharification method that hydrolyzes cellulose using an enzyme or a microorganism that produces the enzyme, and (2) hydrolysis of cellulose using mineral acid. It is roughly divided into acid saccharification methods.

  As a method for obtaining monosaccharides from biomass by hydrolysis using an acid, there are a method using dilute sulfuric acid and a method using concentrated sulfuric acid. For example, a plurality of reaction stages using sulfuric acid having different concentrations is required, and the process Are complicated and require a reaction tank that can withstand high temperatures and high pressures (Non-Patent Document 1: page 112). Moreover, when concentrated sulfuric acid is used, it is difficult to recover high-concentration sulfuric acid, and there are problems that furfural and the like are generated due to excessive decomposition (Non-patent Document 1: page 118).

  On the other hand, the method of obtaining monosaccharides from biomass by hydrolysis using an enzyme can be performed under mild reaction conditions of about 50 ° C., and since it does not use a strong acid, it has the advantages of easy drainage treatment and low environmental impact. is there. And the method of obtaining glucose using an enzyme using cellulose materials, such as waste paper, as a raw material is reported (patent documents 1-4). However, general cellulases are derived from the genus Tricoderma, Acremonium, Aspergillus, and Bacillus, and the optimum pH is in the acidic region, so when performing an enzyme reaction Needs to adjust the sample to acidic. In order to adjust the sample to be acidic, a method of adding an acid to the sample can be considered. However, when the sample is basic, a large amount of acid is required, which is not efficient. In particular, paper often contains basic calcium carbonate as a filler or pigment, and there is a need for the development of technology to efficiently produce sugar from cellulosic materials such as waste paper and paper sludge. It was.

  As a saccharification method for a cellulose-containing material containing calcium carbonate, a technique described in Patent Document 5 has been proposed. In Patent Document 5, in order to efficiently produce sugar from a cellulose-containing material containing calcium carbonate that exhibits basicity, first, the cellulose-containing material is treated with cellulase in a neutral or alkaline manner, and then carbonated by solid-liquid separation. After removing calcium, cellulase is added again to perform hydrolysis under acidic or neutral conditions.

JP 2002-176997 A JP 2002-186938 A JP 2006-088136 A JP 2006-204294 A JP 2008-161137 A

Alcohol Association edited by “Bioethanol Production Technology” (Industry Research Committee, 2007)

  In recent years, the use of high-filling paper has progressed, and the proportion of calcium carbonate contained in waste paper and paper sludge has increased. Since calcium carbonate generally exhibits basicity, a dispersion containing a large amount of calcium carbonate has an alkaline pH. However, since the optimum pH of general cellulase is in the acidic region, it is necessary to adjust the pH to the acidic region in order to obtain monosaccharides using the enzyme containing cellulose-containing materials containing calcium carbonate. , PH adjustment requires a lot of acid and is not efficient. As an enzyme used for hydrolysis of cellulose, an enzyme having an optimal pH from acidic to neutral may be used, but such an enzyme is expensive and lacks competitiveness in terms of cost.

  In view of such circumstances, an object of the present invention is to provide a technique for efficiently hydrolyzing a cellulose-containing material containing calcium carbonate such as waste paper using cellulase having an optimum pH in an acidic region. .

  In order to solve the above-mentioned problems, the present invention has been researched. As a result, after the cellulose-containing material is hydrolyzed with cellulase having an optimum pH in the acidic region in the neutral or alkaline region, calcium carbonate is removed by solid-liquid separation. Then, the inventors have found that sugar can be efficiently produced using a cellulose-containing material containing calcium carbonate as a raw material by adjusting the reaction liquid to a neutral or acidic region and performing hydrolysis, and have completed the present invention.

That is, the present invention includes, but is not limited to, the following inventions.
(1) A step of bringing a cellulase having an optimum pH of 3 to 7 into contact with a cellulose-containing material containing calcium carbonate at pH 7 to 11 to saccharify the cellulose-containing material; removing calcium carbonate from the reaction solution by solid-liquid separation And adjusting the pH of the reaction solution from which calcium carbonate has been removed to 3-7, and saccharifying the cellulose-containing material with the cellulase at pH 3-7; How to manufacture.
(2) The method according to (1), wherein the cellulose-containing material containing calcium carbonate is at least one selected from waste paper, waste containing waste paper, and paper sludge recovered from a paper pulp factory.
(3) The method according to (1) or (2), wherein the cellulase is at least one selected from endoglucanase, exoglucanase, and β-glucosidase.

  ADVANTAGE OF THE INVENTION According to this invention, saccharide | sugar can be efficiently manufactured using a cellulase using the cellulose containing material containing calcium carbonates, such as used paper and paper sludge. In particular, according to the present invention, sugar can be produced with a relatively small amount of cellulase, and sugar can be produced by a method with low acid consumption.

  The sugar obtained by the present invention may be used as it is, and can also be used as a raw material for producing ethanol by alcohol fermentation or the like. In addition, according to the present invention, a useful substance can be produced using waste such as waste paper and paper sludge as a raw material. Therefore, the present invention is preferable from the viewpoint of effective utilization of biomass, waste treatment, and the like. It is also an excellent technology.

FIG. 1 is a graph showing the amount of glucose produced in Examples and Comparative Examples.

  Hereinafter, although the form for implementing this invention is demonstrated in detail, this invention is not limited to the following specific form at all, It can implement by changing suitably.

In the present invention, a cellulose-containing material containing calcium carbonate is used as a raw material. The cellulose-containing material containing calcium carbonate of the present invention is not particularly limited. For example, waste paper such as newspaper, magazine, office paper, and corrugated paper; waste containing waste paper; recovered from a paper pulp factory Sludge to be generated; broke generated in the papermaking process and the like, and a mixture thereof may be used. Generally, since calcium carbonate is used as a filler in paper, waste paper or the like contains internally added calcium carbonate. In addition, in coated paper coated with a pigment, calcium carbonate is generally used as a pigment, so that the coated paper contains externally added calcium carbonate.

  Examples of the used paper of the present invention include newspapers, magazines, office paper such as copy paper, and paperboard such as corrugated cardboard. In addition to used paper discharged from homes, business used paper and printers, etc. Used paper that is discharged from the market. Further, in the present invention, selected used paper selected from high quality paper, medium quality paper, lower grade paper, newspaper, flyers, magazines, etc., or unselected used paper in which various used papers are mixed may be used as a raw material.

  Moreover, the waste containing the used paper of the present invention is a waste containing not only used paper but also other materials such as plastic and wood. In general, waste containing waste paper may be used as a raw material for alternative fuels such as waste solid fuel (RDF) and RPF (Refuse Paper and Plastic Fuel). Waste including waste paper can be effectively used as a raw material for sugar and the like.

  Furthermore, sludge collected from a paper pulp factory is generally called paper sludge (PS) and contains fiber such as cellulose and inorganic particles such as calcium carbonate. Examples of the wastewater from the pulp and paper mill used as the basis of the sludge used in the present invention include wastewater washed away from the waste paper recycling process (DIP manufacturing process), the pulp manufacturing process, the papermaking process, and the white papermaking water. Sludge is mainly composed of solids in such waste water.

  Furthermore, the broke from the paper making process is a dry paper or a wet paper that is generated by a paper break, a stoppage, a cutting, or the like in the paper making process, and is also called a damaged paper. The broke from such a papermaking process contains cellulose, and further contains calcium carbonate added internally or externally.

  Although there is no restriction | limiting in the quantity of the calcium carbonate contained in the cellulose containing material of this invention, For example, the thing whose calcium carbonate content is about 5-65 weight% is common, and about 10-50 weight% is contained. Cellulose-containing materials are more common.

  In addition, the cellulose-containing material of the present invention can be pretreated to increase the efficiency of the enzymatic hydrolysis reaction. As a pretreatment of the cellulose-containing material, chemical treatment using chemicals such as acid or alkali, beating, and mechanical treatment such as freeze pulverization can be performed. For example, treatment for shortening fibers, cutting, etc. Shredding, dispersing in water and loosening the fibers can be suitably performed.

Step of Hydrolyzing Cellulose-Containing Material from Neutral to Alkaline In the present invention, first, a cellulose-containing material containing calcium carbonate is hydrolyzed using an enzyme at pH 7-11. By this hydrolysis, soluble sugars such as short fibers in which cellulose is decomposed, oligosaccharides, polysaccharides, low molecular weight sugars such as xylose, and the like are generated from the cellulose-containing material.

  The enzyme used in the present invention is a general cellulase. Specifically, the optimum pH is acidic to neutral, preferably the optimum pH is 3 to 7, and more preferably the optimum pH is 4 to 6. Cellulase. In general, such a cellulase has a certain activity even in a pH range of 7 to 11 which is a neutral to alkaline region, and therefore, the cellulose-containing material can be hydrolyzed in the present invention. Cellulases used in the present invention include the genus Tricoderma, the genus Aspergillus, the genus Bacillus, the genus Acremonium, the genus Irpex, the genus Aeromonas, the genus Clostridium, Enzymes such as Pseudomonas genus, Penicillium genus, Humicola genus and / or enzymes produced by genetic recombination can be used alone or in combination, and filamentous fungi, basidiomycetes, bacteria, etc. The cellulase can be used. Cellulase can also be used directly from commercially available cellulase preparations, cultures of the above-mentioned bacteria, and filtrates thereof. Among them, cellulases such as the genus Tricoderma, the genus Acremonium, the genus Aspergillus, the genus Bacillus can be preferably used. As the cellulase, a mixture of a plurality of cellulases can be used. For example, a cellulase containing one or more of endoglucanase, exoglucanase and / or β-glucosidase can be preferably used.

  In the present invention, the amount of cellulase used is not particularly limited, but the amount of cellulase used relative to the substrate is preferably 0.1 to 30% by weight, more preferably 0.5 to 5% by weight. If the amount of cellulase used relative to the substrate is less than 0.1% by weight, the enzyme treatment takes a long time, which is problematic in terms of performance. On the other hand, when the amount exceeds 30% by weight, the treatment capacity is not improved so much as the amount of the enzyme used is increased.

  In the present invention, the hydrolysis reaction is carried out from neutral to alkaline, but since the calcium carbonate contained in the cellulose-containing material, which is the raw material, is basic, if the raw material is dispersed in water, the dispersion is neutral to alkaline. Is often indicated. In particular, when pH adjustment is necessary, the pH can be adjusted using a general acid or base.

  The temperature in the first step may be a temperature at which cellulase, which is an enzyme, shows activity, and can be, for example, about 30 to 70 ° C, preferably about 30 to 60 ° C, and about 35 to 55 ° C. More preferably, about 35-50 degreeC is further more preferable. Although the length of the 1st process can be suitably adjusted according to the property and use of a raw material, it can be set as about 3-74 hours, for example, Preferably it is about 6-72 hours.

  In the present invention, in order to improve the reaction efficiency between the cellulose-containing material and cellulase, stirring or the like may be performed. The specific stirring device is not particularly limited. For example, a device that rotates a bar, plate, or propeller-shaped stirrer in a tank at a constant speed in one direction, or stirs the stirrer intermittently or reversely. Can be mentioned. There may be one or more stirrers, and a plurality of stirrers can be rotated in reverse to each other, or a protrusion or plate combined with the stirrer can be attached to the tank side to enhance the stirring effect. Further, the stirrer can be directly rotated via a rotating shaft, or can be rotated from the outside using a magnetic force or the like. In addition, the cellulose-containing slurry can be stirred by generating a flow with a pump or the like.

  In the present invention, the dissolved state of calcium carbonate is determined by measuring the calcium ion concentration in the solution portion using a hardness measurement kit (LCK327; Dr. Lange) and a multi-item water quality meter (LASA30; Dr. Lange). You can figure it out.

  In the present invention, it is preferable to use a dispersion in which a cellulose-containing material containing calcium carbonate is dispersed in water. Specifically, a cellulose-containing material containing calcium carbonate can be added to water and subjected to an appropriate dispersion treatment to prepare a slurry of the cellulose-containing material. The concentration of the slurry can be appropriately determined according to the performance of the liquid feed pump, etc., but taking into account the fluidity and cost of the slurry, it is preferably 1 to 60% solids, more preferably 1 to 50% solids. preferable.

Step of removing calcium carbonate In the present invention, the sugar-containing liquid, which is the reaction solution of the saccharification step, is subjected to solid-liquid separation to remove solid calcium carbonate. As described above, the sugar-containing liquid obtained by the saccharification reaction contains insoluble components such as calcium carbonate in addition to low-molecular soluble sugars such as cellooligosaccharide, xylooligosaccharide, and xylose, and cellulase. By removing calcium carbonate by solid-liquid separation, pH adjustment becomes easier in the subsequent third step, and the efficiency of the third step can be increased by removing insoluble components such as calcium carbonate.

  As a method for removing calcium carbonate, a general solid-liquid separation method can be used. For example, solid-liquid separation can be performed by methods such as filtration, centrifugation, and sedimentation. Specifically, for example, cellulose can be separated as a solid using a filter paper, a filter cloth, a filtration membrane, a centrifuge, etc., but when solid-liquid separation is performed by a pressure type such as a filter press, This is preferable because solid-liquid separation is possible.

  In this process, in addition to calcium carbonate, insoluble substances such as lignin, hemicellulose, and some cellulases adsorbed on the fiber are removed as a solid phase, but the liquid phase contains cellooligosaccharides, xylooligosaccharides, polysaccharides, xylose, etc. Low molecular weight soluble sugars, cellulases and the like. The solid content (saccharification residue) removed in this step may be incinerated and thermally recycled, or cellulase contained in the solid content can be reused.

Step of Hydrolyzing Cellulose-Containing Material from Acid to Neutral In the present invention, the reaction solution obtained by solid-liquid separation is adjusted to pH 3 to 7, and further a saccharification reaction is performed. In this step, it is not necessary to newly add an enzyme, and after adjusting the pH of the reaction solution, hydrolysis of low-molecular sugars and the like with cellulase is performed under appropriate conditions to obtain a saccharified solution containing glucose. Can do.

  In the present invention, a part of the cellulase used in the first step is adsorbed to cellulose and the like and removed out of the system in the second step, but a part of the cellulase remains in the reaction solution. Progresses. As raw materials for the saccharification reaction, soluble polysaccharides, oligosaccharides and the like produced from cellulose in the first step are used, and monosaccharides such as glucose are obtained.

  The reaction conditions in this step are not particularly limited except for pH, and can be set to appropriate conditions. Specifically, the temperature can be a temperature at which cellulase as an enzyme exhibits activity, for example, about 30 to 70 ° C, preferably about 30 to 60 ° C, more preferably about 35 to 55 ° C, About 35-50 degreeC is further more preferable. Moreover, although reaction time can be suitably adjusted according to the property and use of a raw material, it can be set as about 3-74 hours, for example, Preferably it is about 6-72 hours. Moreover, you may stir etc. also in this process similarly to a 1st process.

  Examples of the sugar obtained by the present invention include monosaccharides and oligosaccharides. Specifically, glucose (glucose), galactose, mannose, fructose and the like as monosaccharides, and lactose (lactose) and sucrose (as oligosaccharides). Sucrose) and disaccharides such as maltose (maltose). Such sugar can be used as a useful product as it is, or can be used as a raw material for alcohol fermentation or the like in the production of biofuel, and thus has extremely high value.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples. Unless otherwise specified, in this specification, concentrations and the like are based on weight, and numerical ranges are described as including the end points.

Example 1
As the cellulose-containing material containing calcium carbonate, paper sludge recovered from the used paper recycling process of the paper mill was used. This paper sludge contained pulp fibers, calcium carbonate, etc. (fiber content 85%, calcium carbonate content 10%).

  A 1 L beaker was used as a saccharification tank. Hydrolysis was performed using a dispersion (pH: 7.5) in which 5 g of the paper sludge was dispersed in 495 g of water. As an enzyme having an optimum pH of about 4.5, 4% of a commercially available cellulase (Meiselase, manufactured by Meiji Seika Co., Ltd .: optimum temperature of about 55 ° C., Trichoderma spp.) Was added to the solid content of the pulp dispersion.

  In the first step, the pulp dispersion and the enzyme were put into a 1 L beaker, and these were reacted for 6 hours with stirring to saccharify the cellulose-containing material. The saccharification reaction was performed at a temperature of about 40 ° C. and a rotation speed of about 300 rpm. The glucose content after completion of the first step was measured using the following glucose kit.

  In the second step, the reaction solution was suction filtered using a filter paper, and the filtrate was used in the third step.

  In the third step, sulfuric acid (96% sulfuric acid, Wako Pure Chemical Industries, Ltd.) was added to the filtrate placed in a 1 L beaker to adjust the pH to about 4.7, and a saccharification reaction was performed while stirring. The saccharification reaction was performed at a temperature of about 40 ° C. and a rotation speed of about 300 rpm.

  The glucose content of the saccharified solution was measured using a glucose kit (trade name: Glucose CII-Test Wako, Wako Pure Chemical Industries).

Comparative Example 1
Cellulose-containing in the same manner as in Example 1 except that the second step (removal of calcium carbonate by solid-liquid separation) and the third step (saccharification under acidic conditions) were not performed, and only the first step was continued. The product was saccharified and the glucose concentration of the saccharified solution was measured.

  The results of the experiment are shown in Table 1. As is apparent from the results in Table 1, when the cellulose-containing material is treated according to the present invention, sugar can be efficiently produced, and in this example, the reaction is completed in 9 hours. Moreover, by removing calcium carbonate by solid-liquid separation, the pH of the reaction solution can be adjusted to the acidic side with a relatively small amount of acid, and sugar can be produced efficiently. Furthermore, according to the present invention, it is not necessary to add cellulase in the third step, and sugar can be produced by a simple method.

  On the other hand, in the case of the comparative example, even if the saccharification reaction is performed for 12 hours, the amount of saccharification when the reaction is performed for 9 hours in Example 1 is not reached. In this regard, in the examples, solid-liquid separation and pH adjustment were performed at 6 hours from the start of the reaction, so that the saccharification reaction proceeded smoothly even after pH adjustment, and glucose could be obtained efficiently. Therefore, compared with the case where an enzyme is simply added to a sample as in the comparative example, the present invention can produce a certain amount of glucose in a shorter time using the same amount of enzyme. In addition, when the reaction time is constant, according to the present invention, a constant amount of glucose can be produced with a smaller amount of enzyme.

Claims (3)

A step of bringing a cellulase having an optimum pH of 3 to 7 into contact with a cellulose-containing material containing calcium carbonate at pH 7 to 11 to saccharify the cellulose-containing material,
Removing calcium carbonate from the reaction solution by solid-liquid separation; and
Adjusting the pH of the reaction solution from which calcium carbonate has been removed to 3-7, and saccharifying the cellulose-containing material with the cellulase at pH 3-7,
A method for producing sugar from a cellulose-containing material containing calcium carbonate.   The method according to claim 1, wherein the cellulose-containing material containing calcium carbonate is one or more selected from waste paper, waste containing waste paper, and paper sludge recovered from a paper pulp mill.   The method according to claim 1 or 2, wherein the cellulase is at least one selected from endoglucanase, exoglucanase, and β-glucosidase.

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