JP4928254B2 - Method for saccharification of cellulose-containing materials - Google Patents

Description

    The present invention relates to a method for saccharifying a cellulose-containing material containing calcium carbonate.

    As a method for saccharifying a cellulose-containing material typified by paper, a method for obtaining saccharides such as glucose by hydrolysis by enzyme treatment using cellulase is widely known. Since these cellulases have an appropriate pH in an acidic to neutral region, an aqueous solution is prepared in the acidic region and an enzyme reaction is performed.

There are Patent Documents 1 and 2 as methods for obtaining glucose by saccharifying cellulose-containing materials such as waste papers. However, hydrolysis using cellulase is carried out in a neutral to alkaline region, hydrolysis using β-glucosidase. There is no previous method for removing solids containing calcium carbonate.
JP 2002-176997 A JP 2002-186938 A

    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. An aqueous solution containing a large amount of calcium carbonate has a high pH (pH 7 to 9), and adjustment with a large number of acids is required in order to perform an enzyme reaction in an acidic region. Accordingly, an object of the present invention is to provide a saccharification method that consumes less acid in cellulose-containing materials.

As a result of repeated research to solve the above-mentioned problems, the present invention has been obtained by decomposing cellulose into low-molecular sugars in a neutral or alkaline region and then removing solids containing calcium carbonate by dehydration. Attention was focused on a “method for obtaining a saccharified solution containing glucose by further enzymatic treatment of only soluble components in a neutral or acidic region, preferably pH 4-7”.

    According to the present invention, saccharification of a cellulose-containing material containing calcium carbonate can be provided by a method that is efficient and consumes less acid.

    Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications.

    In the present invention, the cellulose-containing material is not particularly limited, but used paper such as newspaper, magazine, office paper, and corrugated paper, sludge containing fibers generated from the wastewater treatment process of a pulp and paper factory, and the like are used. The

    FIG. 1 is a process diagram showing one embodiment of the method for saccharification of a cellulose-containing material of the present invention. First, in the saccharification step 1 (first step), cellulase is added as the enzyme 5 to the cellulose-containing material 4 pretreated as necessary, and water is further supplied as necessary, followed by stirring at an optimum pH and temperature. Then, cellulose is hydrolyzed by cellulase to obtain a low-molecular sugar-containing substance. General waste paper pre-treatment involves treatment with chemicals such as acids and alkalis, beating, mechanical destruction by freeze grinding, etc., and pre-treatment such as shortening the fibers, and shredding only with cutting There is a simple pretreatment that does not cut the fiber, just adding water to the used paper and mixing it to loosen the fiber. In the present invention, the latter simple pretreatment is preferable in consideration of cost and complexity of the treatment.

    The cellulase used in the first step of the present invention includes at least endoglucanase, exoglucanase, and β-glucosidase, and is not particularly limited as long as it has activity in a neutral to alkaline region, preferably pH 7 to 10. . The amount of cellulase used relative to the base mass is preferably 0.1 to 30% by weight, particularly preferably 0.5 to 5% by weight.

If the amount of cellulase used relative to the base mass is less than 0.1% by weight, the enzyme treatment takes a long time and there is a problem in terms of performance. On the other hand, if the amount exceeds 30% by weight, the treatment capacity is not improved so much as the amount of the enzyme used is increased.
The amount of water supplied in the saccharification step 1 can be appropriately set such that the slurry containing the cellulose-containing material 4 and the enzyme 5 has a stirrable viscosity. As for the reaction conditions, the pH is preferably neutral to alkaline (pH 7 to 10) and the temperature is preferably about 40 to 70 ° C.

    In the saccharification step 1, cellulose is shortened or saccharified by the action of cellulase on the cellulose contained in the cellulose-containing material 4, and short fibers, oligosaccharides, polysaccharides, low-molecular sugars such as xylose, or other soluble substances Sugar is produced.

    The stirring time is preferably set so that most of the cellulose is dissolved, and for example, about 10 to 50 hours is preferable.

  Next, as a second step, the sugar-containing liquid obtained in the saccharification step 1 is subjected to solid-liquid separation (solid-liquid separation step 2) to obtain a sugar-containing liquid 7 from which the solid content has been removed.

  The sugar-containing liquid obtained in the saccharification step 1 contains insoluble components such as lignin, hemicellulose, and calcium carbonate in addition to low-molecular soluble sugars such as cellooligosaccharide, xylooligosaccharide, and xylose, and cellulase. Moreover, although it is desirable to adjust pH to 4-7 in the saccharification process 3, many acids required for preparation are needed in presence of calcium carbonate. By removing insoluble components such as calcium carbonate in the solid-liquid separation step 2, it is possible to increase the efficiency of the third step and further reduce the required amount of acid.

    As a solid-liquid separation method, a method in which calcium carbonate can be separated as a solid content by a filter cloth, a filtration membrane, centrifugation, or the like is preferable. For example, the method of dehydrating with a filter press is mentioned.

    In the solid-liquid separation step 2, insoluble substances such as lignin, hemicellulose, and calcium carbonate are removed as a solid phase, and the sugar-containing liquid 7 obtained in the liquid phase, that is, the solid-liquid separation step 2, contains cellooligosaccharides, xylooligosaccharides, polysaccharides. , Low molecular soluble sugars such as xylose are produced. A part of the cellulase is adsorbed on the substrate cellulose or the like and removed together with the solid content, but is also contained in the sugar-containing liquid 7.

  The solid content removed in the solid-liquid separation step 2 is appropriately incinerated as the saccharification residue 6. Alternatively, since the removed solid content contains cellulase, when the saccharification treatment is performed again together with the cellulose-containing material 4, the amount of cellulase supplied can be reduced.

  In the next third step, saccharification step 3, cellulase containing β-glucosidase is added to the soluble component containing sugar obtained in solid-liquid separation step 2, and the mixture is stirred at an optimum pH and temperature to reduce the low molecular weight by cellulase. Hydrolysis of sugar or the like is performed to obtain a saccharified solution 9 containing glucose.

  The cellulase used in the third step of the present invention is not particularly limited as long as it contains at least β-glucosidase. The amount of cellulase used relative to the base mass is preferably 0.1 to 30% by weight, particularly preferably 0.5 to 5% by weight. If the amount of cellulase used relative to the base mass is less than 0.1% by weight, the enzyme treatment takes a long time and there is a problem in terms of performance. On the other hand, if the amount exceeds 30% by weight, the treatment capacity is not improved so much as the amount of the enzyme used is increased.

    As the reaction conditions in the saccharification step 3, saccharification conditions using a normal cellulase are applied. For example, pH 4-7 and temperature about 40-70 degreeC are preferable.

  In the saccharification step 3, hydrolysis from oligosaccharide to glucose is mainly performed. The saccharified solution 9 contains saccharides such as glucose and oligosaccharide, cellulase and the like.

  The saccharified solution 9 obtained in the saccharification step 3 generates a valuable material by fermentation such as alcohol fermentation or lactic acid fermentation.

The effects of the present invention will be clarified by showing specific examples below.
Example 1
As a cellulose-containing material, hardwood kraft pulp (LBKP) prepared by adding calcium carbonate and adjusting the pH to 8 to 9 was prepared. A 1 liter beaker was used as a saccharification tank. As enzyme 5, a commercially available cellulase (trade name: Novozyme 51081, manufactured by Novozyme) containing at least endoglucanase, exoglucanase, and β-glucosidase having an optimum pH in a neutral or alkaline region was added to LBKP at 1%. . First, LBKP, water, and an enzyme were put into a 1 liter beaker, and hydrolysis with the enzyme was performed while stirring them (first step). After reacting at a temperature of 50 to 60 ° C. for 25 hours, suction filtration was performed using a filter paper, and the filtrate was put into another 1 l beaker (second step). Sulfuric acid was added to the filtrate to adjust the pH to 5-6. As the enzyme 8, a commercially available cellulase (trade name: Novozyme 188, manufactured by Novozyme) containing at least β-glucosidase having an optimum pH in the acidic region is added to LBKP at 1%, and the enzyme is hydrolyzed while stirring. (Third step). After reacting for 25 hours, the glucose content of the saccharified solution was measured. The results are shown in Table 1 below.
(Example 2)
The cellulose-containing material was saccharified under the same conditions as in Example 1 except that the cellulose-containing material was sludge containing fibers generated from a pulp and paper wastewater treatment plant, and the amount of glucose in the saccharified solution was measured. The results are shown in Table 1 below.
(Comparative Example 1)
In Example 1, enzyme 5 was saccharified using a commercially available enzyme (trade name: celcraft, manufactured by Novozyme) having an optimum pH in the acidic region. Sulfuric acid was added to this filtrate to adjust the pH to 5-6, and the mixture was reacted at a temperature of 50-60 ° C. for 25 hours, and then the glucose concentration of the saccharified solution was measured. The solid-liquid separation process, which is the second process, and the saccharification process, which is the third process, were not performed. The results are shown in Table 1 below.
(Comparative Example 2)
In Example 2, the enzyme 5 was saccharified using a commercially available enzyme (trade name: celcraft, manufactured by Novozyme) having an optimum pH in the acidic region. Sulfuric acid was added to this filtrate to adjust the pH to 5-6, and the mixture was reacted at a temperature of 50-60 ° C. for 25 hours, and then the glucose concentration of the saccharified solution was measured. The solid-liquid separation process, which is the second process, and the saccharification process, which is the third process, were not performed. The results are shown in Table 1 below.
<Result>
Even if the cellulose-containing material containing calcium carbonate was saccharified in the neutral to alkaline region, a saccharification rate equivalent to that obtained when saccharified in the acidic region could be obtained. Moreover, the acid addition amount could be drastically reduced by performing the solid-liquid separation process.

It is process drawing which shows one Example which concerns on this invention.

Explanation of symbols

1 Saccharification process (first process)
2 Solid-liquid separation process (second process)
3 Saccharification process (third process)
4 Cellulose-containing material 5 Enzyme 6 Saccharification residue 7 Sugar-containing liquid 8 Enzyme 9 Saccharified liquid

Claims (5)

A cellulase containing at least endoglucanase, exoglucanase, and β-glucosidase is added to the cellulose-containing product, and the enzyme is treated in a neutral to alkaline region to decompose to low molecular sugars. A second step of removing solids containing calcium, and a low-molecular sugar containing glucose by adding cellulase containing at least β-glucosidase to the obtained soluble component and performing enzyme treatment in a neutral or acidic region A method for saccharifying a cellulose-containing material, comprising a third step of obtaining a saccharified solution. 2. The saccharification of a cellulose-containing material according to claim 1, wherein the low-molecular sugar in the first step is an oligosaccharide or a polysaccharide that is a monosaccharide or a monosaccharide condensate that generates a monosaccharide by hydrolysis. Method. The method for saccharifying a cellulose-containing material according to any one of claims 1 to 2, wherein the neutral or alkaline region in the first step has a pH of 7 to 10. The method for saccharifying a cellulose-containing material according to any one of claims 1 to 3, wherein the neutral or acidic region in the third step is pH 4 to 7. The cellulose-containing material according to any one of claims 1 to 4, wherein the cellulose-containing material is waste paper, waste containing waste paper, or paper sludge containing fibers generated from a draining process of a pulp and paper factory. Saccharification method.

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