JP2013220398A - Method for suppressing bacteria proliferation in ethanol fermentation of kitchen waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently suppress effect of bacteria, which exist in large amounts in kitchen waste derived from general waste, on simultaneous saccharification and fermentation reaction, to consequently improve ethanol yield in applying the kitchen waste existing in the general waste which is only incinerated conventionally to simultaneous saccharification and fermentation to achieve stable reaction, to further improve final ethanol concentration and reduce energy cost necessary for distillation, to reduce a ratio of a facility cost, and, as a result, to utilize organic resource, which is the kitchen waste existing in large amounts in the general waste, as raw material of bio-based fuel.SOLUTION: A method of suppressing bacteria proliferation is characterized by that an antibiotic is added to a simultaneous saccharification and fermentation reaction system in producing ethanol by heat-treating fermentation raw material formed of kitchen waste in general waste in a low-temperature range of 50-100°C, lowering a temperature of obtained heat treated product to a temperature range in which fermenting microorganisms can grow, and bringing the obtained treated material of which a temperature is lowered to the simultaneous saccharification and fermentation reaction system.

Description

  The present invention relates to a method for suppressing the growth of coexisting bacteria to minimize the influence of the bacteria on ethanol fermentation in ethanol production using moss collected from general households.

  Food waste as industrial waste is being reused, and mainly used as composting, methane fermentation, and in recent years as a raw material for producing ethanol. On the other hand, moss (approximately 15% published on the Ministry of the Environment's website in 2007), which accounts for approximately 15% of the approximately 38 million tons of general waste currently being processed by incineration, is incinerated because it contains a lot of water. It is also a cause of calorie reduction at the time, and is often unsuitable as a raw material for producing ethanol due to the mixed state of miscellaneous properties and other components, and the reuse rate is extremely low at present. However, attempts to recycle general waste as organic resources continue. For example, in Patent Documents 1 and 2, general waste is pulverized, and impurities are removed from the pulverized product by mechanical sorting. A method of using the component as a methane fermentation substrate has been proposed. However, this method makes it difficult to perform a stable reaction due to the influence of unsuitable fermentation materials, and has a long residence time. Therefore, there are problems such as residual foreign substances such as sand and metal and damage to the reaction tank. On the other hand, there are many problems regarding the use of methane, and methane obtained by fermentation is often burned without being used for power generation or the like (Patent Document 3). In addition, if fermentation fails due to a change in the balance of methane-fermenting bacteria composed of complex fungi, a large amount of unfermented residue must be processed, and a large amount of cost is required for restarting. And time is needed.

  In recent years, bioethanol has attracted attention as a biofuel that is required to be used for gasoline replacement. Ethanol fermentation has a short residence time compared to methane fermentation and is easy to handle because it is a liquid fuel. However, although studies using food waste as a raw material for ethanol fermentation have been conducted (Patent Document 4), no studies have been reported on ethanol production targeting moss in general waste. The reason is that moss in general waste is not stable in composition as compared with food waste, starch is not abundant in raw materials, and saccharification technology has not been established.

JP 2008-246461 A JP 2008-246462 A JP 2006-297210 A JP 2009-112200 A

  Although it is industrially beneficial to apply this to ethanol fermentation raw materials as a means of recycling moss in general waste, a great number of microorganisms ( Miscellaneous bacteria). On the other hand, food waste with a high starch content as a raw material can be made into a sugar solution with few miscellaneous bacteria by fluidizing it by the action of amylase at a high temperature, and the residence time during fermentation reaction is several hours. Therefore, even if miscellaneous bacteria remain, ethanol can be produced in a state where it is not easily affected.

  When moss in general waste is used as a fermentation raw material, it is considered that a method of producing ethanol by simultaneous saccharification and fermentation by adding cellulase and containing a large amount of cellulose component while containing a large amount of cellulose is considered suitable. It is done. In this case, the reaction period may take several days, which is longer than the simple fermentation of sugar liquor, and there is concern about the effects of various bacteria. Therefore, there is a need for a method for suppressing germs in a simultaneous saccharification and fermentation reaction of raw materials containing moss derived from general waste, which has a feature that many germs exist and the reaction period becomes long.

  The inventors of the present invention have conducted extensive research on a method for suppressing the harmful effects of microorganisms during simultaneous saccharification and fermentation reactions using moss contained in general waste, and as a result, conducted low-temperature heat treatment of raw materials containing moss. In addition, the inventors discovered a method that can obtain an ethanol production efficiency equivalent to that in the absence of various bacteria by adding an antibiotic to the simultaneous saccharification and fermentation reaction system after the temperature drops.

  This invention heat-processes the fermentation raw material which consists of moss in a general waste in the low temperature range of 50 to 100 degreeC, temperature-falls the obtained heat-treated material to the temperature range which can be fermented microorganisms, and obtained temperature-fall process In producing a ethanol by subjecting a product to a simultaneous saccharification and fermentation reaction, an antibiotic is added to the simultaneous saccharification and fermentation reaction system.

  Throughout this specification and claims, general waste refers to waste other than industrial waste as defined by the “Waste Disposal Act (Act on Waste Disposal and Cleaning)”, Most of them are garbage that is discharged in the ordinary life of ordinary households, that is, household waste. Garbage mainly consists of garbage such as litter and garbage from ordinary households, etc., but packaging, containers, disposable chopsticks, collection nets, etc. are mixed, so for example 50% It refers to garbage that occupies the above. It is preferable that the general waste is subjected to a sorting process so that the cocoon constitutes the main component. The sorting method is not particularly limited. For example, sorting means such as gravity sorting and wind sorting can be applied, and manual sorting may be used.

  In the present invention, moss in general waste is used as a raw material for ethanol fermentation.

  The heat treatment in the low temperature region is a heat treatment in a temperature region lower than this while the general sterilization treatment is performed by steam sterilization at a temperature of 100 ° C. or higher, preferably 60 ° C. or higher. More preferably, it is 70 degreeC or more. It is desirable that the heat distribution during the low-temperature heat treatment is uniform, and for this purpose, it is preferable to involve mechanical stirring. Extraction steam may be used as heating means for the low-temperature heat treatment.

  The low temperature heat treatment time is desirably 2 hours or more after reaching a predetermined temperature, and more desirably 4 hours or more. The upper limit of the low temperature heat treatment time is not particularly defined, but is related to the heat treatment temperature and is about 24 hours in consideration of economy.

  Next, the heat-treated product obtained by the low-temperature heat treatment is lowered to the temperature range where the fermentation microorganisms can grow. The viable temperature range of the fermenting microorganism is preferably 4 to 45 ° C, more preferably 28 to 42 ° C, and usually room temperature.

  Next, ethanol is produced by subjecting the temperature-lowered product obtained by the temperature-lowering of the heat-treated product to a simultaneous saccharification and fermentation reaction. The simultaneous saccharification and fermentation is preferably performed at 28 to 42 ° C. for 2 to 7 days in the presence of an enzyme such as Celic, a cellulase manufactured by Novozymes, and an accelerator such as Accel Race, a cellulase manufactured by Genencor, and a yeast such as Saccharomyces cerevisiae. Implemented according to law.

  The antibiotic added to the simultaneous saccharification and fermentation reaction system is a substance generally called an antibiotic. Antibiotics having a broad antibacterial spectrum are preferred, those having a low effective concentration are preferred, and those that can be produced at low cost are more preferred.

  Examples of such antibiotics include actinomycin, azithromycin, aspoxicillin, amphotericin, arbekacin, ampicillin, erythromycin, oxacillin, oxytetracycline, kanamycin, carbenicillin, clindamycin, chloramphenicol, chlortetracycline, gentamicin, cycloserine, dihydro Streptomycin, streptomycin, spectinomycin, cephalosporin, cephalothin, cephaloldin, cefquinome, tylosin, tetracycline, nystatin, neomycin, virginiamycin, hygromycin, bacitracin, paromomycin, vancomycin, puromycin, plastidin, bleomycin, penicillin, polymyxin Mitmaishi , Mycophenolic acid, methicillin, of lincomycin and these drugs derivatives and salts, at least one is appropriately used.

  The added amount of the antibiotic is preferably 2 ppm or more with respect to the weight of the entire simultaneous saccharification and fermentation reaction product. Although the upper limit of this addition amount is not specifically defined, it is about 100 ppm from the cost effectiveness.

  It is also preferable to add an antibiotic at the start of the simultaneous saccharification and fermentation reaction.

  According to the present invention, it is possible to effectively suppress the influence of miscellaneous bacteria present in moss derived from general waste on the simultaneous saccharification and fermentation reaction. As a result, the ethanol yield can be improved and stable reaction can be realized when the moss present in the general waste, which has been conventionally only incinerated, is applied to the raw material for simultaneous saccharification and fermentation. Furthermore, the final ethanol concentration can be improved, the energy cost required for distillation can be reduced, and the proportion of the equipment cost can be reduced. As a result, organic resources such as moss present in general waste can be used as raw materials for biofuels.

It is a graph which shows the ethanol concentration of each sample of the simultaneous saccharification and fermentation reaction 2nd day in an Example. It is a graph which shows the ethanol concentration of each sample of the simultaneous saccharification and fermentation reaction 5th day in an Example. It is a graph which shows the density | concentration of an antibiotic by the photo recorder in a reference example, and a germ growth inhibitory effect.

  Hereinafter, the present invention will be specifically described based on examples and drawings.

[Example] Soot is extracted by hand sorting from municipal solid waste collected by the local government, and mixed with a multiprocessor (PS-3000S manufactured by CHUBU) until the prototype cannot be retained. About 100 kg of the resulting mixture is obtained at 105 ° C. When dried for several hours, the dry weight% was determined to be 30.39%.

  Water was poured into the obtained dried product and the ratio was adjusted to 25% by weight to obtain a plurality of samples. Each sample was subjected to low-temperature heat treatment at 50, 60, 70, and 80 ° C. for 2, 4 hours, respectively. Next, after cooling to room temperature, Cellulase “Accel Race” manufactured by Genencor and yeast “Saccharomyces cerevisiae” were added, and chloramphenicol was added to each reaction system as an antibiotic during the simultaneous saccharification and fermentation reaction. After adding 5 ppm to the mixture and stirring well, a simultaneous saccharification and fermentation reaction was performed.

Comparative Example 1
The operation was performed under the same conditions as in the Examples, except that no antibiotic was added.

Comparative Example 2
As a positive control, the operation was performed under the same conditions as in the examples except that low-temperature heat treatment was performed at 121 ° C. for 20 minutes.

Comparative Example 3
As a negative control, the operation was performed under the same conditions as in the Examples, except that no low temperature heat treatment was performed and no antibiotic was added.

Comparative Example 4
As a negative control, the operation was performed under the same conditions as in Examples, except that low-temperature heat treatment was not performed.

  Table 1 summarizes the treatment conditions of Examples and Comparative Examples and ethanol concentrations after 2 days and 5 days of reaction. The ethanol concentrations after 2 days and 5 days after the reaction are shown in FIGS. According to these results, the results of the simultaneous permeation fermentation reaction that was performed by adding antibiotics to the fermented raw material that had been subjected to low-temperature heat treatment at 60 ° C. for 4 hours were obtained from the fermented raw material that had been subjected to autoclaving, which is a general sterilization method. The result of the simultaneous permeation fermentation reaction used was almost the same, and the result of the low temperature heat treatment at 70 ° C. for 2 hours or more was almost the same as the result of the positive control.

  The effect of the presence of antibiotics, especially when moss is heat-treated at 60 ° C or less, is a remarkable part of the simultaneous saccharification and fermentation reaction system. In view of contamination (contamination) due to germs such as in the above, it can be seen that it is effective not only for effective suppression of germs during the reaction but also for the continuation of a stable reaction.

参考例
５ｍＬの５％ＹＰＤ液体培地に厨芥溶液０．１ｍＬを加え、ここへ抗生剤としてクロラムフェニコールを０〜５ｐｐｍ添加し、温度を６０℃に調整した後、フォトレコーダーを用いてＯＤ＝６００の吸収により雑菌の増殖を観察した。その結果、図３に示すように、２ｐｐｍ以上の抗生剤濃度で良好な雑菌抑制効果が認められた。 In addition, there were some samples in which the ethanol concentration after 5 days (FIG. 2) was lower than the ethanol concentration after 2 days (FIG. 1). This may be because the miscellaneous bacteria assimilated ethanol, or the generated sugar was assimilated by the miscellaneous bacteria, and the yeast for fermentation assimilated ethanol, but in any case the miscellaneous bacteria existed. .

Reference Example 0.1 mL of sputum solution was added to 5 mL of 5% YPD liquid medium, 0-5 ppm of chloramphenicol was added thereto as an antibiotic, the temperature was adjusted to 60 ° C., and then OD = The growth of miscellaneous bacteria was observed by absorption of 600. As a result, as shown in FIG. 3, a good bacteria suppression effect was observed at an antibiotic concentration of 2 ppm or more.

Claims (7)

Fermentation material consisting of moss in general waste is heat-treated in a low temperature range of 50 ° C to 100 ° C, and the resulting heat-treated product is cooled down to the temperature range where fermentation microorganisms can grow, and the resulting temperature-lowered processed product is simultaneously saccharified. A method for inhibiting the growth of miscellaneous bacteria, characterized in that an antibiotic is added to a simultaneous saccharification and fermentation reaction system in producing ethanol by fermentation. The method according to claim 1, wherein the temperature range of the low-temperature heat treatment is 60 ° C or higher. The method according to claim 1 or 2, wherein the low-temperature heat treatment time is 2 hours or more. The method according to any one of claims 1 to 3, wherein the heating means of the low-temperature heat treatment is extracted steam. Antibiotics are actinomycin, azithromycin, aspoxicillin, amphotericin, arbekacin, ampicillin, erythromycin, oxacillin, oxytetracycline, kanamycin, carbenicillin, clindamycin, chloramphenicol, chlortetracycline, gentamicin, cycloserine, dihydrostreptomycin, streptomycin, spectromycin Mycin, cephalosporin, cephalothin, cephalordin, cefquinome, tylosin, tetracycline, nystatin, neomycin, virginiamycin, hygromycin, bacitracin, paromomycin, vancomycin, puromycin, blasticidin, bleomycin, penicillin, polymyxin, mitomycin, mycophenolic acid Chishirin and lincomycin, and methods according to any one of claims 1 to 4 is one or more selected from the group consisting of derivatives and salts. The method according to any one of claims 1 to 5, wherein the antibiotic is added in an amount of 2 ppm or more with respect to the weight of the entire simultaneous saccharification and fermentation reaction system. The method according to any one of claims 1 to 6, wherein an antibiotic is added at the start of the simultaneous saccharification and fermentation reaction.

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