JP2007111590A - Method for manufacturing ethanol from kitchen garbage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing ethanol highly efficiently from a kitchen garbage as a raw material. <P>SOLUTION: The method for manufacturing ethanol from kitchen garbage comprises a step of crushing kitchen garbage to prepare crushed kitchen garbage, a step of forming a saccharified liquid by virtue of a saccharifying enzyme added to the crushed kitchen garbage subsequent to adjusting its starch content, a step of preparing a cultured broth by way of an alcoholic fermentation using pre-cultured spawn of Zymomonas mobilis inoculated to the saccharified liquid, and a step of distilling the cultured broth to recover alcohol. The ethanol conversion with respect to glucose of higher than 45% is obtained by the method, which enables an efficient manufacture of ethanol from kitchen garbage and will contribute to the manufacture of ethanol for use in blending with gasoline in our country. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  While global warming is progressing, oil resources are depleting at the same time, and it is a common challenge for mankind to control oil consumption and replace energy sources with renewable resources, which are photosynthetic products. Yes. In order to achieve the target of the Kyoto Protocol related to carbon dioxide reduction, it was also decided in Japan to add bioethanol produced from renewable resources to gasoline.

  However, in Japan, there are no cheap agricultural products that can produce ethanol and meet demand. Therefore, technology development to produce ethanol by saccharifying wood resources such as building waste materials and wind-fall trees has been actively carried out, but there are technically high hurdles and there is still no economic prospect.

  Ethanol is the main component of all alcoholic beverages such as sake, shochu, beer, wine and whiskey, and has been produced by fermentation using yeast since ancient times. Industrial and fuel products are also produced by fermentation in the United States and Brazil, where agricultural resources are abundant. Incidentally, 25% of bioethanol (fermented ethanol) is added to gasoline in Brazil and 10% in the United States.

  According to the fermentation method, the composition and quality of the raw materials are limited. This is in order to accurately perform the growth of yeast and the metabolic reaction of microorganisms that produce alcohol. In other words, efficient alcoholic fermentation cannot be performed unless the raw materials are distinguished.

  For example, corn starch (cornstarch) can be obtained in large quantities in the United States, and cane molasses and crude syrup obtained from sugarcane in Brazil, making it possible to conduct fermentation for the production of fuel ethanol.

  Now, the ethanol-producing bacterium Zymomonas mobilis is a microorganism involved in the brewing of the Mexican local sake Purke. Although its alcohol production rate is very high, there is no example used for production of industrial ethanol. This is because the ethanol-producing bacterium Zymomonas mobilis requires amino acids and vitamins for growth and the nutrient components of the medium are complex.

  Garbage is a valuable resource that generates 20 million tons per year (Ministry of Agriculture, Forestry and Fisheries statistics) in Japan alone, and technological development to make effective use of this is being considered from various viewpoints. However, what is aimed at energy recovery is mainly by dehydration of raw garbage and self-combustion or anaerobic methane fermentation.

Regarding the energy recovery method using liquid fuel, there are only development examples of acetone / butanol fermentation using raw garbage as raw materials by the present inventors. In acetone / butanol fermentation, the yield (conversion rate) of producing butanol from carbohydrate (glucose) is about 22% on a weight basis. In energy recovery methods using raw garbage as raw materials, there is a need for technological development that can further increase efficiency.
JP 2003-274934 A

  Accordingly, an object of the present invention is to provide a method that can recover ethanol with high efficiency using raw garbage as a raw material.

  The ethanol production method according to the first invention includes a step of pulverizing raw garbage to generate a pulverized product, a step of adjusting the starch concentration of the pulverized product and adding a saccharifying enzyme to generate saccharified treated water, and Inoculating a pre-cultured Zymomonas mobilis inoculum and subjecting it to alcohol fermentation to produce mash, and a step of distilling the mash to recover ethanol.

  In the ethanol production method according to the second invention, in addition to the first invention, water is added to the raw garbage in the step of generating a pulverized product.

  In the ethanol production method according to the third invention, in addition to the first invention, in the step of producing saccharified water, a saccharification enzyme is added after adjusting the starch concentration, and a saccharification reaction is carried out, followed by filtration or used as it is.

  In the ethanol production method according to the fourth invention, in addition to the first invention, in the step of producing saccharified water, a saccharification enzyme obtained after saccharification treatment by adding a saccharification enzyme after adjusting the starch concentration or filtering it is filtered. The liquid obtained is sterilized before use.

  In the ethanol production method according to the fifth invention, in addition to the first invention, the glucose conversion rate is 48%.

  According to the present invention, it is possible to recover ethanol with high efficiency using raw garbage as a raw material. Most of the garbage that is a photosynthetic product is incinerated or dumped without being effectively used, but according to the present invention, ethanol can be efficiently produced from the garbage, and it can be used in the production of ethanol for gasoline addition in Japan. Can contribute.

  The outline of the present invention is as follows.

  Without any special separation work on the garbage, metal pieces, plastics, etc. are removed from the garbage and crushed. Specifically, metals, plastics, wrap sheets, aluminum wheels, disposable chopsticks and other substances that cannot be assimilated by microorganisms or substances that cannot be decomposed by saccharifying enzymes are removed from raw garbage. However, it is not necessary to select the leftovers of food provided as food, and vegetables, fruits, fresh fish, etc. provided as decorations on the table as long as the blades of the grinder are not damaged. These are pulverized while adding a small amount of water.

  Next, a saccharification enzyme is added to the pulverized product after the starch concentration is adjusted, and saccharification treatment is performed to produce saccharification treated water.

  Specifically, first, water is added to the pulverized product to adjust the viscosity so that it can be stirred. Here, the starch contained in the cooked food is already pregelatinized, and liquefaction treatment with a liquefaction enzyme is not necessary, but it is inevitable that the viscosity of the liquid becomes high. Since the moisture of raw garbage is about 75%, even if it is liquefied by adding the same amount of water as raw garbage, the dry matter equivalent concentration of food elements such as starch contained in the finished garbage pulverized liquid is about 12.5. Even if it is saccharified, it is best to obtain a sugar solution having a sugar concentration of 8-9%.

  Furthermore, the adjusted garbage pulverized liquid is adjusted to a pH optimum for the saccharifying enzyme to be used, saccharifying enzyme is added, and the saccharification treatment is performed for a necessary time at an optimum temperature to generate saccharification treated water.

  Garbage, mainly leftovers, contains abundant raw vegetables and fruits, and the action of proteases contained in these also promotes low molecular weight proteins. Such a nutrient-rich substrate with a relatively low concentration of glucose solution and a relatively large amount of protein is more suitable for alcoholic fermentation by Zymomonas than for yeast. In particular, the continuous fermentation method by Zymomonas is very advantageous in producing ethanol for fuel because a very high production rate can be obtained when the alcohol concentration is relatively low (for example, 5-6%).

  Next, the saccharified water is subjected to sterilization only without adding special nutrients as it is / or filtered. Zymomonas mobilis is inoculated with ethanol and fermented to produce moromi. Further, the mash is distilled to recover ethanol. As a result, ethanol can be produced at a conversion rate of 48% with respect to glucose.

  Here, the ethanol-producing bacterium Zymomonas mobilis requires various organic nutrients in addition to sugar as a substrate for cell growth and ethanol production. For this reason, YM Broth (Difco) in which a yeast extract and a malt extract are mixed with sugar is used as a standard medium for performing a culture test. These nutrients are thought to be mainly amino acids and vitamins, but are not specified.

  The inventors of the present invention have conducted extensive research in anticipation that the components of fish and meat contained in raw garbage can be used effectively for the growth of this bacterium. In addition, since fruits such as pineapples that are mixed in raw garbage also have protease activity, raw garbage not only supplies carbohydrates as a raw material for ethanol, but also contains an enzyme source that degrades animal proteins. Thus, the present invention was completed while confirming the effect by conducting experiments under the hypothesis that it is a resource capable of supplying organic nutrients necessary for the growth and alcohol production of Zymomonas mobilis.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
The inoculum was prepared using YM broth (Difco Laboratories, Detroit) as a medium, adjusted to a specified concentration, dispensed 10 ml into a test tube, and heat-sterilized at 115 ° C. for 10 minutes. This was inoculated with Zymomonas mobilis NRRL B-14023 and statically cultured at 30 ° C. for 18 hours.

  Raw garbage is 120 g of bento rice leftover rice (with a piece of shiso-flavored rice with a pickled plum), chicken cutlet, hijiki simmered, simmered pork and pork, 120 g of side dishes, 1 slice of figs with skin, 100 g of fruit consisting of 3 kyoho grapes Was used as a material.

  200 ml of water was added to this and pulverized with a juicer mixer with the skin and seeds attached. After pulverization, water was further added to make a total of 500 ml. After adjusting the pH to 4.5 with 0.1 N NaOH, 100 μl of saccharification enzyme Detrozyme (Novo) was added and the whole was mixed once again with a juicer mixer. The saccharification reaction was performed in a hot water bath at 60 ° C. for 24 hours. The sugar concentration (in terms of glucose) of the saccharification treatment solution was 92 g / l. 50 ml each of this filtered with a gauze cloth with a drawstring squeeze and / or unfiltered liquid is dispensed into a large test tube, sterilized at 115 ° C. for 10 min in an autoclave, and inoculated with 2.5 ml of the inoculum prepared by the above method And cultured at 30 ° C. for 15 hours. It was 40.5 g / l when ethanol of the fermentation end liquid was analyzed.

  A total of 200 ml of the culture solution (moromi) thus cultured was distilled to obtain 8 ml of absolute ethanol.

(Example 2)
The bacteria, medium, fermentation method, and fermentation conditions used for the seeds are the same as in Example 1.

  The raw garbage was made from 110 g of sandwich (egg and vegetables), 100 g of cheese pizza, and 100 g of papaya (with skin).

  200 ml of water was added thereto, and the papaya skin was pulverized as it was with a juicer mixer. After pulverization, water was further added to make a total of 500 ml. After adjusting the pH to 4.5 with 0.1 N NaOH, 100 μl of saccharification enzyme Detrozyme (Novo) was added and the whole was mixed once again with a juicer mixer. The saccharification reaction was performed in a hot water bath at 60 ° C. for 24 hours. The sugar concentration (in terms of glucose) of the saccharification treatment solution was 83 g / l. This was filtered with a gauze cloth with a drawstring squeezed and / or unfiltered, 50 ml each was dispensed into large test tubes, sterilized at 115 ° C. for 10 min and then inoculated with the inoculum prepared by the above method, and 30 ° C. for 15 h. Cultured. It was 36 g / l when ethanol of the fermentation finished liquid was analyzed.

  A total of 200 ml of the culture solution (moromi) thus cultured was distilled to obtain 7 ml of absolute ethanol.

(Example 3)
The inoculum was prepared by using YM broth (Difco Laboratories, Detroit) as a medium, dispensing 10 ml into a test tube after adjusting to a specified concentration, and heat-sterilizing at 115 ° C. for 10 minutes, then inoculating Zymomonas mobilis NRRL B-14003 Then, a starter was prepared by static fermentation at 30 ° C. for 18 hours.

100 ml of a medium consisting of 50 g / l of glucose, 5 g / l of yeast extract, and 1 g / l of KH ₂ PO _{4 is} placed in a thick glass bottle and seeded in 5 ml of a seed medium sterilized by heating at 115 ° C. for 10 minutes. Fermented for hours.

  Raw garbage is 1kg sushi from leftovers for social gatherings (sushi rolls, eggs, shrimp, tuna nigiri sushi), sandwiches (egg, vegetables, ham), bowls (tempura, fried chicken), fruits (pineapple, orange) ) A total of 1 kg was used.

The decorative vinyl or the like was removed, and about 1 liter of water was added and pulverized as it was. After pulverization, water was further added to make 2 l. After adjusting the pH to 4.5 with 0.1 N NaOH, 500 μl of saccharification enzyme Detrozyme (Novo) was added, and the whole was well mixed and stirred with a stirrer. The saccharification reaction was performed in a hot water bath at 60 ° C. for 24 hours. The sugar concentration (in terms of glucose) of the saccharification treatment solution was 92 g / l. This was centrifuged at 3,000 g for 2 min to obtain 1.8 l of a clarified sugar solution. The sugar solution was adjusted to pH 6.2, sterilized at 115 ° C. for 10 minutes, placed in a 2.5 liter glass jar fermenter, inoculated with the seed (100 ml) adjusted as described above, and cultured at 30 ° C. for 15 hours. During the fermentation, the stirring speed was 150 rpm. The pH was controlled to 5.5 with 1N-NH ₄ OH. The fermentation was completed in 16 hours of culture, and the ethanol concentration was analyzed and found to be 42 g / l.

  This culture solution (moromi) was distilled to obtain 80 ml of absolute ethanol.

Claims (5)

Crushing raw garbage to produce a crushed material;
Adjusting the starch concentration of the pulverized product and adding a saccharifying enzyme to produce saccharified water;
Inoculating the inoculum of Zymomonas mobilis pre-cultured in the saccharified water and subjecting it to alcohol fermentation to produce moromi;
And a step of recovering ethanol by distilling the mash. The method for producing ethanol from raw garbage according to claim 1, wherein water is added to the raw garbage in the step of generating the pulverized product. The method for producing ethanol from raw garbage according to claim 1 or 2, wherein, in the step of producing the saccharified water, the saccharifying enzyme is added after adjusting the starch concentration to perform a saccharification reaction and then filtered or used as it is. The saccharification treated water is used in the step of producing the saccharified water, wherein the saccharification enzyme obtained by adding the saccharification enzyme after adjusting the starch concentration and the saccharification treatment or the solution obtained by filtering the saccharification treatment is used after sterilization. Ethanol production method from raw garbage. The method for producing ethanol from raw garbage according to claim 1, wherein the conversion rate to glucose is 48%.