JP4714862B2 - Method for producing and separating and purifying succinic acid from raw garbage - Google Patents

Description

The present invention refers to organic waste such as food waste and raw garbage discharged from households, hotels / inns, hospitals, schools, restaurants / canteens, food factories, farms and livestock farms, etc. The present invention relates to a method for producing succinic acid using waste as a raw material, and a method for separating and purifying the produced succinic acid.

At present, raw garbage is mainly treated by incineration or landfill, despite containing various effective resources. Also, in some cases, a method of recycling as compost (compost) without discarding as it is has been proposed. However, there is a problem of shortage of landfill when performing the landfill processing of garbage, and there is a problem that a large facility is required for performing the incineration process, and further, a bad odor is generated. Further, the method of recycling raw garbage as compost is not only an effective solution because of the time required for processing but also the imbalance between the demand for compost and the amount of raw garbage to be processed.

On the other hand, succinic acid has many demands in the chemical and food industries as a food additive, plating agent, photographic developer, pharmaceutical raw material, detergent builder, resin raw material, raw material for polybutyl succinic acid, a biodegradable plastic, etc. ing. And when it sees as a raw material of the biodegradable plastic decomposed | disassembled in a natural environment especially, reduction of the production cost of a raw material is anxious.

Conventionally, succinic acid is obtained by hydrogenation of fumaric acid or maleic acid, reduction of malic acid with hydrogen iodide, fermentation of ammonium tartrate or calcium malate, and the like. As a crystallization method of succinic acid, Patent Document 1 discloses that maleic anhydride or maleic acid is reduced to succinic acid in an aqueous solution, and then the aqueous solution is cooled and crystallized to obtain succinic acid as crystal particles. In addition, Patent Document 2 proposes a method for regulating the particle size and particle size distribution of succinic acid, which is an improvement of the above method. However, these proposals do not touch on the relevance of garbage.
Japanese Patent Publication No.44-29246 JP 2005-82498 A

Until now, a method of producing an organic acid such as lactic acid, acetic acid, propionic acid by microbial fermentation of garbage has been proposed (for example, Patent Document 3). However, in Patent Document 3, succinic acid is not obtained. Patent Document 4 proposes a method of collecting succinic acid from a reaction solution by allowing a microorganism belonging to the genus Brevibacterium to act on an aqueous reaction solution containing fumaric acid or a salt thereof. Patent Document 5 also proposes a method for producing succinic acid using microorganisms, in particular, anaerobiospiril rim succinici produce. However, neither Patent Documents 4 and 5 describe any relevance to the processing of garbage.
Japanese Patent Laid-Open No. 10-174592 JP-A-5-68576 JP 62-294090 A

An object of the present invention is to provide a method for producing succinic acid from raw garbage that is discarded in large quantities every day by an inexpensive and efficient method, and an efficient method for separating and purifying the produced succinic acid. To do.

The present invention is a method for producing succinic acid, characterized in that succinic acid is produced by succinic acid fermentation using a saccharified solution of garbage as a substrate. Another aspect of the present invention is to add succinic acid to a fermentation medium by adding and mixing a mixture of water and alcohol to a fermentation medium in which succinic acid is produced by succinic acid fermentation using a saccharified liquid of raw garbage as a substrate. It is a method for separating and purifying succinic acid, characterized in that the succinic acid is precipitated and separated from succinate. In the present invention, the term “succinic acid” includes succinic acid salts unless otherwise specifically used.

By utilizing succinic acid fermentation, it is possible to effectively use raw garbage and to produce succinic acid at low cost and efficiently. The obtained succinic acid can be separated and purified by a simple method.

In the present invention, garbage refers to organic waste such as food waste and garbage discharged from households, hotels / inns, hospitals, schools, restaurants / canteens, food factories, agricultural and livestock farms, etc., or confirmation of the effects of the present invention. To do this, it means organic waste that has been calibrated and blended in the laboratory. Moreover, what is usually discarded as “burning garbage” such as paper, plastic, and wood chips may be mixed. Such a raw garbage saccharified solution is already known by a method already proposed by the present inventor (see, for example, JP-A No. 2002-119295). It means a liquid containing sugar obtained by acting. Examples of the acid include sulfuric acid, hydrochloric acid, and nitric acid, and one or more of these can be used. As the saccharifying enzyme, glucoamylase, α-amylase, β-amylase, pullulanase, cellulase or the like is preferably used.

The raw garbage contains many carbohydrates, proteins, amino acids, organic acids, lipids, and inorganic substances such as vitamins or minerals as its composition. These can be broadly divided into three groups: (1) fat-soluble components (lipids, etc.), (2) neutral components (sugars), and (3) ionic components (proteins, amino acids, organic acids, inorganic salts, etc.). It can be divided into two. Then, an acid and / or a saccharifying enzyme is allowed to act on the garbage, and the processed product is subjected to solid-liquid separation, thereby obtaining a saccharified solution containing sugar. In this process, high-molecular sugars such as starch and cellulose contained in garbage are hydrolyzed into monosaccharides, disaccharides, trisaccharides and oligosaccharides. Prior to this step, the garbage may be subjected to preservative treatment or added with water to adjust the concentration. The solid residue that has not been saccharified may be separated and removed. However, in the succinic acid fermentation of the present invention, the succinic acid fermentation can be performed while the solid is present. A method using a saccharified solution separated by solid-liquid separation or further produced using an ion exchange membrane or the like is preferred. Conventionally known solid-liquid separation methods can be used for solid-liquid separation. For example, there are compression filtration, membrane separation, filter press, centrifugal sedimentation method and the like. Finally, the residue is used as fertilizer, feed additive, etc., or incinerated or landfilled in some cases. The concentration of glucose in the saccharified solution is suitably about 10 to 80 g / l, preferably 20 to 60 g / l.

The microorganism used for the succinic acid fermentation of the present invention is not particularly limited as long as it is cultured using the raw garbage saccharified solution as a substrate and has succinic acid producing activity. For example, microorganisms belonging to the genus Actinobacillus, the genus Brevibacterium (see JP-A-5-68576), the genus Candida (see Japanese Patent Publication No. 56-17077), or the anaerobiospill Although it is possible to use Anaerobiospirillum succiniciproducens (Japanese Patent Laid-Open No. 62-294090), microorganisms belonging to the genus Actinobacillus are preferred.

In the present invention, the substrate can be used as it is after adjusting the pH, but a substance usually used for adjusting the medium may be added to the substrate. In the present invention, it is preferable to add a nitrogen source such as yeast extract, corn leachate, or polypeptone to the substrate. The addition amount is suitably 1 to 20 g / l.

If the culture conditions for succinic acid fermentation are facultative anaerobic, it can be set appropriately within the range of normal microorganism culture conditions. However, the atmosphere needs to contain carbon dioxide gas, and all the aeration gas may be carbon dioxide gas. However, nitrogen or hydrogen may be mixed as long as oxygen does not enter.

Another aspect of the present invention is that, as described above, alcohol is added to a fermentation medium in which succinic acid is produced by succinic acid fermentation using a saccharified liquid of garbage as a substrate, thereby reducing the solubility of succinate. This is a method for separating and purifying succinic acid, in which an acid is precipitated and separated from a fermentation medium as a succinate. Alkali metal or alkaline earth metal hydroxide, alkali metal or alkaline earth metal carbonate is used as an alkali to be added in order to keep the fermentation medium near neutral (about pH 6 to 8) and to make succinic acid a salt. And salts, ammonium compounds and mixtures thereof. Specific examples include sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, aqueous ammonia, ammonium carbonate, and ammonium bicarbonate. The addition amount may be more than a sufficient amount necessary to make all the succinic acid produced into a salt form. In addition, since the alkali is always added at the stage of adjusting and indicating the fermentation pH (pH 6.0 to 6.5), succinic acid is usually present in a salt form in the fermentation medium.

In the present invention, in order to precipitate and separate succinic acid as a succinate from the fermentation medium, a mixed solution of water and alcohol is added to and mixed with the cultured medium, but the alcohol is not particularly limited. For example, methanol, ethanol, propyl alcohol, or a mixture thereof can be used, but methanol and ethanol are preferable, and ethanol is particularly preferable. The liquid mixture preferably contains 1: 1 or more alcohol by weight, and the addition temperature is preferably room temperature.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

[Example 1]
As a model of raw garbage discharged from households, synthetic food waste adjusted at a ratio of 38% by weight of vegetables and fruits, 19% by weight of meat and fish, 43% by weight of rice and bread, and 10% by weight of water as a whole In addition, what was applied to the mixer was used. 30 kg of this raw garbage was put into a drum-type device, 300 ppm of glucoamylase was added, and saccharification was carried out by stirring at 50 rpm for 6 hours at 50 ° C. The obtained product was filtered through a 6 × 6 mm wire mesh to obtain 20 kg of a saccharified solution. The obtained saccharified solution was centrifuged to remove suspended matters and boiled to remove proteins to obtain a transparent saccharified solution. The glucose concentration in the saccharified solution was 60 g / l.

50 ml of the transparent saccharified solution was inoculated with 1 ml of culture seed of Actinobacillus succinogenes (ATCC 55618). The culture seed is obtained by culturing 1 loop of succinogenase in 50 ml of Trypticase Soy Broth according to a conventional method. The inoculated saccharified solution was placed in an Erlenmeyer flask, and 2.5 g of MgCO ₃ was added thereto to adjust the pH to neutral. The atmosphere was replaced with carbon dioxide and Na ₂ S · 9H ₂ O (1 mg / l), and the mixture was cultured at 39 ° C. for 48 hours with stirring at 65 rpm. The succinic acid concentration in the liquid after the culture was measured with a high performance liquid chromatograph, and the results are shown in Table 1.

The inoculated saccharified solution was put into a bioreactor having a volume of 1 liter, adjusted to pH 6.5 with NaOH, and cultured at 39 ° C. for 48 hours while stirring at 100 rpm while flowing carbon dioxide as an atmosphere. In the case of this large culture, the same results as described above were obtained.

[Examples 2 to 4]
Polypeptone (Example 2), corn leachate (Example 3), and yeast extract (Example 4) as nitrogen sources are added to 50 ml of the transparent saccharified solution, and cultured under the same conditions. The succinic acid concentration was measured and the results are shown in Table 1. Table 1 shows that when various nitrogen sources are added, the amount of succinic acid produced is increased.

[Example 5]
The culture solution (fermentation medium) obtained after the large-scale culture in Example 1 was filtered through a 0.45 μm membrane filter, and the water was evaporated until the water content reached about 60% by weight. The content of sodium succinate in this fermentation medium was 22%.

The fermentation medium was divided into 50 ml fractions and each was placed in an Erlenmeyer flask. A predetermined amount of ethanol was added to each flask to adjust the ratio of the mixture of water and ethanol. And it stirred at 500 rpm for 30 minutes. Then, it vacuum-filtered using the filter made from a 3.0 micrometer polytetrafluoroethylene, and isolate | separated the succinate. The fractionated succinate was vacuum dried at 80 ° C. for 10 hours to obtain a powdered succinate. The recovery rate of succinate when the mixing ratio of water and ethanol is changed is shown in FIG. In FIG. 1, the vertical axis represents the recovery rate (%) of succinate.

[Example 6]
The same experiment as in Example 5 was performed except that the ethanol in Example 5 was changed to methanol. The result was as shown in FIG. In FIG. 2, the vertical axis represents the recovery rate (%) of succinate.

1 and 2 that ethanol generally precipitates succinate more efficiently than methanol. Moreover, the purity of the obtained succinate was very high at 95% or more.

Since raw garbage can be recycled and various chemical raw materials, especially succinic acid, which is a raw material of polybutyl succinic acid, which is a biodegradable plastic, can be produced inexpensively and efficiently, Contributes to low-cost production of biodegradable plastics. Further, the process of the present invention can be incorporated and implemented as an integral part of a resource recycling system for raw garbage by utilizing waste heat from waste power generation in combination with a waste power generation system or process.

The figure which shows the collection | recovery rate of a succinate when the liquid mixture of water and ethanol is used. The figure which shows the collection | recovery rate of a succinate in the case of using the liquid mixture of water and methanol.

Claims (1)

Fermentation of succinic acid by adding a mixture of water and alcohol to a fermentation medium in which succinic acid is produced by succinic acid fermentation by microorganisms belonging to the genus Actinobacillus, using saccharified liquid of raw garbage as a substrate A method for separating and purifying succinic acid, wherein the succinic acid is precipitated and separated from a medium as succinate.

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