JP2008104452A - Alcohol production system and alcohol production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alcohol production system and an alcohol production method, capable of utilizing garbage by using a simple system formation and steps. <P>SOLUTION: A saccharification/first fermentation part 11 reacts a garbage W1 with an enzyme to produce saccharification products and performs alcohol fermentation by using the produced saccharification products. Dilution of the garbage W1 is made unnecessary and solid-liquid separation and concentration are also made unnecessary. A part of the produced Moromi (unrefined fermentation resultant liquid) S1 is used in the next alcohol fermentation to repeat batch fermentations, or, a part of the Moromi S1 is returned to the start of the saccharification/first fermentation part 11 to perform continuous fermentation. A cultivated yeast may be supplied to the saccharification/first fermentation part 11 continuously or batch wise to perform continuous fermentation. The remaining part of the Moromi S1 is separated into a crude alcohol L2 and a distillation residue S2 and an alcohol anhydride L1 is obtained from the crude alcohol L2. The distillation residue S2 is committed to methane fermentation; a digestion residue S3 is dried to produce a compost S4, and the biogas G1 is used as an energy source. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an alcohol production system and an alcohol production method capable of obtaining fuel alcohol from waste such as garbage.

  In recent years, the use of biomass has attracted attention from the viewpoint of global environmental problems. In particular, research and development on technology for producing alcohol such as ethanol, which is expected as a next-generation automobile fuel, from biomass has been actively conducted. This alcohol production is performed by decomposing biomass raw material by a saccharification step such as hydrolysis and then converting it to ethanol by alcohol fermentation using yeast (microorganism).

  As general biomass materials, those containing sugars such as sugar cane or starches such as corn are often used. In addition, plant-based materials such as bagasse and rice straw, wood-based materials such as wood chips, and cellulose-based materials such as biomass are also used as materials. However, sugar and starch materials such as sugarcane and corn are inherently edible resources, and it is preferable to use these edible resources as resources for industrial use over the long term in order to antagonize future population growth problems. Absent.

Therefore, recently, biomass using industrial waste and the like has been studied, and for example, a method of generating alcohol from waste building materials and the like that can be used as cellulosic resources has been proposed (for example, see Patent Document 1). ).
JP 2004-187650 A

  On the other hand, the development of alcohol for fuel from garbage is also under development, but the system configuration and process are complicated, requiring enormous energy input, and there are problems such as waste liquid treatment after distillation. There was still room for improvement.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an alcohol production system and an alcohol production method thereof that can effectively use garbage with a simple system configuration and process.

  The alcohol production system according to the present invention includes a saccharification / first fermentation unit that saccharifies solid food waste to produce a saccharified product and performs alcohol fermentation using the generated saccharified product. In this specification, “garbage” refers to garbage including foods before and after heating (such as leftover food) discarded from households, hotels, convenience stores, etc., and as its components, neutral components (such as sugars), It contains fat-soluble components (lipids, etc.) or ionic components (proteins, amino acids, organic acids, inorganic salts, etc.) and the like. In addition, garbage that is normally discarded as “burning garbage” such as paper and wood chips may be mixed. Further, the “solid garbage” here refers to garbage which is not hydrated, that is, not diluted with water, and water may be mixed in the garbage.

  The alcohol production method according to the present invention includes a saccharification / first fermentation step in which a saccharified product is produced by saccharifying solid garbage in the solid state, and alcohol fermentation is performed using the produced saccharified product.

  In the alcohol production system of the present invention and the alcohol production method of the present invention, solid garbage is saccharified, and alcohol fermentation is performed using the produced saccharified product. Therefore, it is not necessary to dilute the garbage with water and the like, and solid-liquid separation and concentration after saccharification are not required, and the system configuration and process are significantly simplified.

  In particular, in the saccharification / first fermentation section (process), it is preferable to simultaneously perform saccharification of garbage and alcohol fermentation. This is because glucose produced by saccharification can be immediately converted to alcohol by yeast, and the risk of contamination with bacteria can be extremely reduced.

  In this alcohol production system and method, it is preferable to use a part of the koji produced in the saccharification / first fermentation section (process) for the next alcohol fermentation. This is because repeated batch fermentation can be made possible.

  Moreover, it is preferable to return part of the koji produced in the saccharification / first fermentation section (process) to the beginning of the saccharification / first fermentation process. This is because stable continuous fermentation can be achieved.

  Furthermore, in this alcohol production system and method, it is preferable that the yeast is cultured in the yeast supply unit and continuously or intermittently supplied to the saccharification / first fermentation unit (process). This is because stable continuous fermentation can be achieved.

  This alcohol production system and method, for example, distills the koji produced by the saccharification / first fermentation unit and separates it into crude alcohol and distillation residue, and dehydrates the crude alcohol to produce alcohol. It is preferable to have a dehydrating part (process) to perform. The obtained alcohol can be effectively used as, for example, automobile fuel.

  Furthermore, this alcohol production system and method includes a second fermentation section (process) having a methane fermentation tank for fermenting a distillation residue discharged from the distillation section (process), and a digestion discharged from the second fermentation section (process). It is preferable to have a drying section (step) for drying the residue. As a result, the digestion residue can be dried and used as compost or the like, and the conventional waste liquid treatment after distillation becomes unnecessary. Therefore, the treatment of the distillation residue and the digestion residue can be performed with an extremely simple system configuration and process as compared with the prior art.

  In the second fermentation part, it is preferable to produce biogas and use this biogas as an energy source for at least one of the distillation part and the drying part. Thereby, it is not necessary to input energy into the distillation part or the drying part from the outside, and a complete process can be established.

  In the second fermentation section, it is preferable to reduce the concentration of hydrogen sulfide in the biogas by air or sulfur-oxidizing bacteria by introducing air into the methane fermentation tank and bringing it into contact with the biogas. Specifically, the second fermentation unit has, for example, a water tank after the methane fermenter, and circulates a mixed gas of biogas and air between the methane fermenter and the water tank so that hydrogen sulfide is removed from the air. Oxidation or oxidation by sulfur-oxidizing bacteria can be converted into sulfur or sulfate ions, and the concentration of hydrogen sulfide in the mixed gas can be reduced to 10 ppm or less.

  In the alcohol production system of the present invention and the alcohol production method of the present invention, saccharification / first fermentation is applied to household garbage and a mixture of household and business garbage containing 10% or more of holocellulose. Prior to saccharification, it is preferable to liquefy with a liquefying enzyme. Examples of the saccharifying enzyme include glucoamylase and cellulase, but it is more preferable to use both in combination.

  According to the alcohol production system of the present invention or the alcohol production method of the present invention, the solid waste in the saccharification / first fermentation part (process) is saccharified and subjected to alcohol fermentation. There is no need for dilution, and solid-liquid separation and concentration after saccharification can be eliminated. Therefore, the system configuration and process can be remarkably simplified.

  In particular, if saccharification of garbage and alcoholic fermentation are performed simultaneously, glucose produced by saccharification can be immediately converted to alcohol by yeast, and the risk of contamination with germs can be extremely reduced.

  If a part of the koji produced in the saccharification / first fermentation part (process) is used for the next alcohol fermentation, repeated batch fermentation can be performed.

  If a part of the koji produced in the saccharification / first fermentation part (process) is returned to the beginning of the saccharification / first fermentation process, stable continuous fermentation can be achieved.

  If yeast is cultured in the yeast supply unit and continuously or intermittently supplied to the saccharification / first fermentation unit (process), stable continuous fermentation can be achieved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 shows a configuration example of an alcohol production system 1 according to the first embodiment of the present invention. The alcohol production method of the present invention is embodied in the operation of the alcohol production system 1 and will be described together.

  The alcohol production system 1 generates fuel or industrial alcohol from biomass raw material, and includes, for example, an alcohol production unit 10 and a residue treatment / use unit 20. The biomass raw material is, for example, garbage W1 discharged from households or as industrial waste. Therefore, the alcohol production system 1 is also a solution to the problem of waste disposal.

  The alcohol production unit 10 includes, for example, a saccharification / first fermentation unit 11, a distillation unit 12, and a dehydration unit 13.

  The saccharification / first fermentation unit 11 reacts the solid food waste W1 with an enzyme to saccharify starch and some cellulose contained in the food waste W1 to produce a saccharified product. Alcohol fermentation is performed with yeast added and used to produce cocoon S1. Thereby, in this alcohol production system 1, it is not necessary to dilute the garbage W1 with water and the like, and solid-liquid separation and concentration after saccharification are not required, and the garbage W1 is effectively used with an extremely simple system configuration and process. Be able to. The water content of the solid waste W1 is, for example, 70% or more, specifically 75% to 80% or more.

  The saccharification / first fermentation unit 11 preferably performs saccharification of garbage and alcohol fermentation at the same time. This is because glucose produced by saccharification can be immediately converted to alcohol by yeast, and the risk of contamination with bacteria can be extremely reduced. The saccharification / first fermentation unit 11 may perform alcohol fermentation after saccharifying raw garbage.

  In the saccharification / first fermentation unit 11, it is preferable to return a part of the generated koji S1 to the saccharification / first fermentation unit 11 itself without sending it to the distillation unit 12 and use it for the next alcoholic fermentation. This is because repeated batch fermentation can be made possible.

  The saccharification / alcohol fermentation reaction tank used for the saccharification / first fermentation unit 11 is preferably composed of, for example, a good contact between garbage and an enzyme, such as a rotating drum or a rotating blade. It is done. In particular, the rotating blade is preferable because after the saccharification is completed, the saccharified product can be recovered and then the saccharified residue can be recovered while roughly pulverized. The reaction tank is not limited to a horizontal type and may be a vertical type.

  The distillation part 12 distills the koji S1 produced by the saccharification / first fermentation part 11 and separates it into a crude alcohol L2 and a distillation residue S3.

  The dehydrating unit 13 dehydrates the crude alcohol L2 to generate the anhydrous alcohol L1. This anhydrous alcohol L1 is used, for example, added to gasoline.

  The residue processing / utilizing unit 20 includes, for example, a second fermentation unit 21, a cogeneration unit 22, and a drying unit 23.

  The second fermentation unit 21 performs methane fermentation of the distillation residue S2 discharged from the distillation unit 12.

  The cogeneration unit 22 includes, for example, a boiler and a generator (both not shown), and uses the biogas G1 generated in the second fermentation unit 21 as an energy source to generate steam G3 and plant power E1. It is to convert energy. The steam G3 is preferably used as an energy source of at least one of the distillation unit 12 and the drying unit 23. This is because it is not necessary to input energy from the outside to the plant including the distillation unit 12 and the drying unit 23, and a complete process can be established.

  The drying unit 23 dries the digest residue S3 discharged from the second fermentation unit 21 to generate compost S4. The digestion residue S3 includes, for example, organic substances and inorganic substances that have not been digested by the methane fermentation in the second fermentation unit 21.

  FIG. 2 shows the configuration of the second fermentation unit 21. The 2nd fermentation part 21 has 21A of methane fermenters which ferment the distillation residue S2 discharged | emitted in the distillation part 12, for example. A water tank 21B is provided downstream of the methane fermentation tank 21A. The water in the water tank 21B may be any of ground water, river water, industrial water, tap water, or treated water from a sewage treatment plant.

  The methane fermentation tank 21A can introduce air, and it is preferable to reduce the concentration of hydrogen sulfide in the biogas G1 by bringing the biogas G1 generated inside into contact with the air introduced from the outside. The biogas G1 contains unnecessary carbon dioxide, hydrogen sulfide, and ammonia in addition to methane (CH4) useful as an energy source. Since hydrogen sulfide corrodes gas engines and boilers, dry desulfurization, wet desulfurization, and biological desulfurization are generally performed, but there are problems of secondary contamination and processing costs. Thus, by bringing the biogas G1 into contact with air, the concentration of hydrogen sulfide can be easily reduced. Therefore, inhibition by hydrogen sulfide can be reduced and the organic matter load of methane fermentation can be improved. For example, the inflow amount of air is preferably 5% or more and 10% or less of the generation amount of the biogas G1. Moreover, it is preferable that the density | concentration of the hydrogen sulfide in mixed gas G2 containing biogas G1 and air is 10 ppm or less, for example.

  The water tank 21B circulates the mixed gas G2 with the methane fermentation tank 21A to oxidize hydrogen sulfide to air or sulfur or sulfate ions to further reduce the concentration of hydrogen sulfide in the mixed gas G2. is there. By doing in this way, biogas G1 or mixed gas G2 can be desulfurized easily, and it can make it easy to utilize as an energy source of the distillation part 12 or the drying part 23. FIG.

  Further, the mixed gas G2 is passed through the water tank 21B, and ammonia contained in the biogas G1 is removed as ammonium sulfate. Thereby, ammonia inhibition can be reduced and the organic substance load of methane fermentation can be improved. In addition, this ammonia is the ammonium ion contained in garbage, or the ammonium ion which produced | generated and deaminated the protein in the 2nd fermentation part 21 by hydrolyzing a protein, and became ammonia.

  Next, the operation of the alcohol production system 1 having such a configuration will be described.

(Saccharification / first fermentation process)
First, after mixing coarsely ground and foreign matter removed garbage W1 with enzyme and yeast, in the saccharification / first fermentation part 11 of the alcohol production part 10, the solid state garbage W1 is saccharified to produce a saccharified product such as glucose. And is fermented with alcohol using the produced saccharified product. As a result, it is not necessary to dilute the garbage with water or the like, and solid-liquid separation and concentration after saccharification are not necessary, and the process can be simplified greatly.

  Further, by eliminating the need for solid-liquid separation and concentration after saccharification, it is possible to increase the recovery rate of saccharified products and reduce energy loss. Hereinafter, for example, taking a balance of 1 kg of garbage, when saccharification and alcohol fermentation are performed simultaneously as in the present embodiment, the glucose recovery rate after saccharification is 100%. On the other hand, when 1 kg of garbage is diluted with 0.5 kg of water as in the past, 1.125 kg of saccharified solution and 0.375 kg of residue are generated. That is, since one-fourth moves to the residue side, the glucose recovery rate was 75%.

  As for the energy loss rate, assuming that the saccharified solution is concentrated twice, the energy of 343 kcal is required to evaporate the water of 1.125 kg to 0.563 kg of the saccharified solution as shown in Equation 1. Become.

(Equation 1)
0.563 × (539+ (100−30)) = 343 kcal

  Furthermore, by simultaneously performing saccharification and alcohol fermentation, glucose produced by saccharification can be immediately converted to alcohol by yeast. Therefore, the risk of contamination can be extremely reduced.

  As specific saccharification conditions in such a saccharification / first fermentation step, for example, when saccharification and first fermentation are performed simultaneously, a temperature of 20 ° C. or higher, preferably 40 ° C. or lower is preferable. This is because the temperature cannot be increased for the yeast to live. In the case of performing the first fermentation after saccharification, the saccharification temperature may be increased to 60 degrees, but it is preferable to decrease the temperature in alcohol fermentation. The amount of the enzyme is preferably 50 mg or more, more preferably 100 mg or more with respect to 1 kg of the wet weight of the solid garbage W1. Here, the wet weight means the weight (mass) including liquid waste mixed in food waste.

  Further, during collection and transportation and saccharification, lactic acid fermentation is mainly caused by microorganisms that live in the garbage W1, and the saccharified product contains an organic acid A mainly composed of lactic acid A1. Thereby, the hydrogen ion index (pH) of the saccharified product is maintained at, for example, pH 3.5 or more and 4.5 or less.

  The concentration of lactic acid A1 produced during collection and transportation and saccharification is, for example, preferably 5000 mg / l or more, more preferably 10,000 mg / l or more. This is because the pH of the saccharified product can be lowered, the growth of various bacteria can be suppressed, and sterilization of the saccharified product can be made unnecessary. In addition, by setting the concentration of lactic acid A1 within this range, the pH of the saccharified product is naturally in the range of 3.5 to 4.5, and the yeast used for alcoholic fermentation grows in this pH range. There is no need to specifically adjust the pH of the.

  As yeast used for alcoholic fermentation, at least one of non-aggregating yeast and aggregating yeast that grow and ferment even at a pH of 4.5 or less can be used. Specifically, examples of the non-aggregating yeast include Saccharomyces cereviciae EP1 strain and Kagoshima yeast No. 5 used in shochu production, and examples of the aggregating yeast include Saccharomyces cereviciae KF-7 strain.

  As a method of alcohol fermentation, batch fermentation, repeated batch fermentation or continuous fermentation can be used. As the batch fermentation, a fed-batch fermentation method may be used, and as the repeated batch fermentation, a method using an apparatus that performs automation based on the amount of gas generated or a method of repeating batch fermentation once a day is preferable. A chemostat system is preferred.

As specific alcohol fermentation conditions, for example, the continuous fermentation method is applied, the alcohol fermentation temperature is 25 ° C. or higher, preferably 30 ° C. or higher, and the dilution rate D is 0.05 h ⁻¹ or higher, preferably 0.2 h ^{−. 1} or more, more preferably 0.3 h ^-1 or more. Here, the dilution rate D (h ⁻¹ ) is a value obtained by dividing the garbage supply rate F (m ³ / h) by the actual volume V (m ³ ) of the saccharification / first fermentation unit 11 (D = F / V ).

In the alcohol fermentation, sterilization treatment or pH adjustment may be performed in order to further reduce the remaining germs or a suitable pH state. For example, by setting the dilution rate D to 0.2 h ⁻¹ or more around pH 4 of the saccharified product and the above-described lactic acid concentration and around fermentation pH 4, it is possible to completely prevent germs from breeding during alcohol fermentation. Become.

  Thus, it is preferable that a part of koji S1 produced in the saccharification / first fermentation step is not used for the next alcoholic fermentation in the saccharification / first fermentation step again without being sent to the distillation step. This is because repeated batch fermentation can be made possible.

(Distillation process)
Next, in the distillation unit 12, the koji S1 generated by the saccharification / first fermentation step is distilled and separated into the crude alcohol L2 and the distillation residue S2.

(Dehydration process)
Subsequently, in the dehydrating unit 13, the crude alcohol L2 is dehydrated to generate the alcohol L1.

  On the other hand, the distillation residue S2 discharged from the alcohol production unit 10 is sent to the residue processing / use unit 20 for processing or use as follows.

(Second fermentation process)
First, in the methane fermenter 21 </ b> A of the second fermentation unit 21, the distillation residue S <b> 2 discharged from the distillation process is subjected to methane fermentation to generate biogas G <b> 1. Since this biogas G1 contains carbon dioxide gas, hydrogen sulfide, ammonia and the like in addition to methane (CH ₄ ) that is useful as an energy source, by introducing air into the methane fermentation tank 21A, Air is contacted, and the concentration of hydrogen sulfide contained in the biogas G1 is reduced to, for example, 10 ppm or less. Thereby, the bad influence to the human body by a hydrogen sulfide and the corrosion of a boiler and a generator can be prevented. The inflow amount of air is preferably 5% to 10% of the amount of biogas G1 generated, for example. Moreover, it is preferable to further reduce the concentration of hydrogen sulfide in the mixed gas G2 by circulating the mixed gas G2 between the methane fermentation tank 21A and the water tank 21B.

  Moreover, it is preferable to pass the mixed gas G2 through the water tank 21B and remove ammonia contained in the biogas G1 as ammonium sulfate. This is because ammonia inhibition can be reduced and the organic load of methane fermentation can be improved.

  The biogas G1 (mixed gas G2) from which hydrogen sulfide has been removed is sent to the cogeneration unit 22 where it is converted into steam G3 and plant power E1. The steam G3 is used as a heat source for at least one of the distillation unit 12 and the drying unit 23. Electric power E1 is used in the plant.

(Drying process)
Moreover, in the drying part 23, the digestion residue S3 discharged | emitted from the 2nd fermentation process is dried, and compost S4 is obtained. As a result, the waste liquid treatment after distillation as in the prior art becomes unnecessary, and the treatment of the distillation residue S2 and the digestion residue S3 can be performed with an extremely simple system configuration and process as compared with the conventional case.

  FIG. 3 is a diagram showing the balance of balance between generated energy and consumed energy per ton of garbage in the above alcohol production method. The amount of energy generation is 569,300 kcal, which is the total of 244,800 kcal by the alcohol L1 produced by the dehydration unit 13 and 324,500 kcal by the biogas G1 obtained by the second fermentation unit 21. On the other hand, the energy consumption is 25,000 kcal as fuel for a collection vehicle for collecting garbage, 86,000 kcal as plant power for the saccharification / first fermentation unit 11, and 130, as energy consumption in the distillation unit 12. The total of 100 kcal, 125,300 kcal as the energy consumed in the dewatering unit 13 and 171,900 kcal as the energy consumed in the drying unit 23 is 538,500 kcal. As described above, in the present embodiment, the energy generation amount is larger than the consumption amount, and it is possible to realize a self-contained process that does not require external energy input and does not require wastewater treatment.

  As described above, according to the present embodiment, the solid waste W1 is saccharified in the saccharification / first fermentation unit 11, and alcohol fermentation is performed using the generated saccharified product. There is no need to dilute with water, and solid-liquid separation and concentration after saccharification can be eliminated. Therefore, the garbage W1 can be effectively used with an extremely simple system configuration and process.

  In addition, by eliminating solid-liquid separation and concentration, it is possible to increase the recovery rate of saccharified material and reduce energy loss.

  In particular, since saccharification and alcohol fermentation are performed simultaneously, the produced saccharified product can be immediately converted into alcohol, and the risk of contamination with bacteria can be extremely reduced. Moreover, since it is not necessary to provide the apparatus of saccharification and alcohol fermentation separately, plant cost can be reduced. Furthermore, compared to performing saccharification by raising the temperature to 60 degrees and then lowering the temperature to 30 degrees to perform alcoholic fermentation, the temperature should be consistently reduced to about 30 degrees when saccharification and alcoholic fermentation are performed simultaneously. Energy consumption can be reduced.

  Furthermore, since a part of koji S1 produced | generated in the saccharification and the 1st fermentation part 11 was used for the next alcoholic fermentation, it can make a repeated batch fermentation possible.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, a part of the koji S1 generated in the saccharification / first fermentation step is returned to the beginning of the saccharification / first fermentation step, that is, a part of the koji S1 and the enzyme are added to the solid waste W1. In addition, it is the same as the alcohol production method of the first embodiment except that the saccharification / first fermentation step is performed. The alcohol production system is the same as the alcohol production system described with reference to FIG. 1 in the first embodiment.

  In the present embodiment, since a part of koji S1 produced in the saccharification / first fermentation step is returned to the beginning of the saccharification / first fermentation step, stable continuous fermentation can be achieved.

[Third Embodiment]
FIG. 4 shows the configuration of an alcohol production system according to the third embodiment of the present invention. This alcohol production system has the same configuration as the alcohol production system of the first embodiment except that the yeast supply unit 14 is connected to the saccharification / first fermentation unit 11. Therefore, the same components are described with the same reference numerals.

  The yeast supply unit 14 cultures yeast and supplies the saccharification / first fermentation unit 11 continuously or intermittently. Thereby, in this alcohol production system, stable continuous fermentation can be enabled.

  When such a yeast supply unit 14 is provided, it is not always necessary to return a part of the koji S1 to the saccharification / first fermentation unit 11, but it may be returned.

  In the present embodiment, since yeast is cultured in the yeast supply unit 14 and continuously or intermittently supplied to the saccharification / first fermentation unit 11, stable continuous fermentation can be performed.

[Fourth Embodiment]
FIG. 5 shows an alcohol production method according to the fourth embodiment of the present invention. This alcohol production method is the same as the alcohol production method of the first embodiment except that a garbage disposal step S31 is included before the saccharification / first fermentation step S11. Therefore, the description of the same process is omitted.

(Garbage disposal process)
First, in the garbage processing step S31, 10% or less, preferably 1% or less of the lactic acid bacteria culture solution L0 is added to the garbage W1 by surface spraying, and then placed in an anaerobic condition such as by placing cobblestone. Here, the two methods shown in FIGS. 6A and 6B can be considered. In the method shown in FIG. 6A, lactic acid bacteria are sprayed on the surface of the garbage W1 and placed in an anaerobic state by putting a weight stone, for example, for 6 days. On the other hand, the method shown in FIG. 6 (B) corresponds to garbage discharged every day, and the next day's garbage W12 is added to the previous day's garbage W1, and the lactic acid bacteria culture solution is sprayed on the surface in the same manner. Put a weight stone. This operation is repeated every day, for example, 6 days. As will be apparent from the examples described later, the method of FIG. 6B, that is, the method of adding garbage every day and spraying lactic acid bacteria on the surface each time has an excellent glucose recovery rate.

  In the present embodiment, by the method of FIG. 6 (A) or FIG. 6 (B), preferably FIG. 6 (B), a part of the garbage W1 is lactic acid fermented, the pH is lowered, and the garbage W1 Freshness is preserved. Therefore, the decay of the garbage W1 is prevented, and a reduction in the recovery rate of saccharified products due to the decay and generation of organic acids that inhibit alcohol fermentation such as acetic acid in the garbage W1 containing sugar are suppressed. Thus, the processing waste W2 is obtained by processing the garbage W1.

(Saccharification / first fermentation process)
Next, in the first saccharification / first fermentation step S11, the solid waste W2 is saccharified to produce a saccharified product, for example, glucose, and the produced saccharified product is used for alcohol fermentation.

  At that time, as specific saccharification conditions, when saccharification and alcohol fermentation are performed simultaneously, after treating waste W2, enzyme F, and yeast, the temperature is set to 20 ° C or higher, preferably 40 ° C or lower. When alcohol fermentation is performed after saccharification, the treated waste W2 and the enzyme F are mixed and saccharified at a temperature of 30 ° C or higher, preferably 50 ° C or higher, and then yeast is added to perform alcoholic fermentation. The enzyme F may be an acid-resistant enzyme that works even at a pH of about 3, such as an acid-resistant glucoamylase. Alternatively, glucoamylase having acid resistance and heat resistance may be used. In addition, a cellulase enzyme may be added after such an enzyme is added. Furthermore, sugar can be recovered more efficiently by pre-treating food waste by a method such as heat treatment and then saccharifying it. About the quantity of the enzyme F, it is preferable to set it as 50 mg or more with respect to 1 kg of the wet process waste W2, and also 100 mg or more.

  The yeast used for alcoholic fermentation, the method of alcoholic fermentation, the fermentation conditions, and the like are the same as in the first to third embodiments. Further, the steps after the distillation step are the same as those in the first to third embodiments.

  As described above, according to the present embodiment, in the garbage processing step S31, 10% or less, preferably 1% or less of the lactic acid bacteria culture solution L0 is added to the garbage W1 by surface spraying or the like and then held in an anaerobic state. Therefore, the freshness of the garbage W1 can be maintained. Therefore, it is possible to prevent the decay of the garbage W1, and to suppress the reduction in the recovery rate of the saccharified product due to the decay and the generation of organic acids that inhibit alcohol fermentation such as acetic acid in the garbage W1 containing the saccharified product. It becomes possible to produce sugar efficiently. The sugar (glucose) thus produced can be used not only as an alcohol but also as a raw material for production of useful substances and as a raw material for a fuel cell such as a glucose battery.

  In the above explanation, mainly garbage with large starch content and low holocellulose content (business-related waste) was explained, but household waste with high holocellulose content The following embodiment is effective for a mixture of household and business food waste.

[Fifth Embodiment]
FIG. 7 shows an alcohol production method according to the fifth embodiment of the present invention. This alcohol production method is the same as the alcohol production method of the fourth embodiment, except that an enzyme liquefaction step S32 is included after the garbage processing step S31 and before the saccharification / first fermentation step S11. It is. Therefore, the description of the same process is omitted.

  Generally, household garbage contains 10% or more of holocellulose in a polysaccharide. In addition, the ratio of holocellulose here represents holocellulose / polysaccharide = holocellulose / (starchy + holocellulose), and holocellulose includes cellulose and hemicellulose.

  That is, in the present embodiment, a liquefied enzyme such as Termamyl is added and liquefied in the enzyme liquefaction step S32 to the treated waste W2 processed in the garbage processing step S31. In the saccharification / first fermentation step S11, the liquefied treated waste W3 is subjected to saccharification / fermentation using glucoamylase or cellulase, or glucoamylase and cellulase in combination as a saccharifying enzyme.

  Thus, the collection rate of glucose becomes high by performing the liquefaction process in the enzyme liquefaction step S32 for the household garbage and the mixture of household and business garbage having a high holocellulose content. In particular, by performing saccharification using a combination of glucoamylase and cellulase, the glucose recovery rate becomes higher.

  Furthermore, specific examples of the present invention will be described.

[Example 1]
A batch fermentation test of garbage was conducted in the same manner as in the fourth embodiment, and the concentrations of organic acid and ethanol were examined. First, food waste such as rice cake or leftovers was used as the food waste W1, and the food waste W1 was kept fresh in the food waste treatment step S31 by the method of FIG. After removing foreign matter from the treated waste W2, 1 kg (wet weight) was collected and coarsely pulverized.

(Preparation of pre-culture solution)
The pre-culture solution should be stored in a 5% YPD medium (glucose 5 g / l, yeast extract (YE) 1 g / l, polypeptone 1 g / l) in a slant (slope medium; method of storing yeast in an agar medium). Oita Kagoshima No. 5 was inoculated with 1 platinum ear and then cultured by shaking at 30 degrees and 160 rpm for 16 hours.

(Simultaneous Saccharification and Fermentation (SSF))
Subsequently, 100 g of the treated waste W2 was collected and put into an empty sterilized 300 ml Erlenmeyer flask, 13 mg of Nagase ChemteX Corporation Nagase Enzyme N-40 was added as a glucoamylase, and prepared as described above. 10 ml of the preculture was put into an Erlenmeyer flask. Thereafter, this Erlenmeyer flask was immersed in a constant temperature water bath at 30 ° C., and a saccharification / ethanol simultaneous fermentation test was performed for 48 hours, and the organic acid concentration (total concentration of lactic acid and acetic acid) and alcohol (ethanol) concentration were examined. The initial pH was examined and found to be 3.9. The obtained results are shown in FIGS. 8 and 9, respectively. In addition, FIG. 10 shows changes over time in organic acid concentrations (concentrations of lactic acid and acetic acid).

[Comparative Example 1]
A batch fermentation test was conducted in the same manner as in Example 1 except that glucoamylase was not added, that is, only alcohol fermentation was performed without saccharification. The obtained results are shown in FIG. 8 and FIG. Moreover, the daily change of organic acid concentration is shown in FIG.

[Example 2]
100 g of treated waste W2 obtained by treating garbage W1 in the same manner as in Example 1 was put into a 300 ml Erlenmeyer flask that had been sterilized empty, and then Nagase Enzyme N-40 of Nagase ChemteX Corporation was used as glucoamylase. 13 mg was added and saccharified for 3 hours at a temperature of 60 degrees. After that, the temperature was lowered to 30 ° C. by water cooling or cooling, 10 ml of the same preculture solution as in Example 1 was added, and an alcoholic fermentation test (batch fermentation) was performed at a temperature of 30 ° C. for 48 hours. The obtained results are shown in FIG. 8 and FIG. Moreover, the daily change of organic acid concentration is shown in FIG.

[Comparative Example 2]
A batch fermentation test was conducted in the same manner as in Example 2 except that after saccharification, the yeast was left without addition (alcohol fermentation was not performed). The obtained results are shown in FIG. 8 and FIG. Moreover, the daily change of organic acid concentration is shown in FIG.

  As can be seen from FIGS. 8 to 13, in Example 1 in which simultaneous saccharification / alcohol fermentation was performed, and in Example 2 in which yeast was added after saccharification and alcohol fermentation was performed, Comparative Example 1 in which only alcohol fermentation was performed and After the saccharification, the ethanol concentration produced was higher than that of Comparative Example 2 which was left without adding yeast. That is, it was found that the amount of ethanol produced can be increased by saccharifying the treated waste W2 obtained by treating the raw garbage W1 and performing alcohol fermentation using the generated saccharified product.

  In Example 2 and Comparative Example 2, since the saccharification was performed by raising the temperature to 60 degrees, the organic acid increased almost even if left at 30 degrees or subjected to alcohol fermentation at 30 degrees. There wasn't.

[Example 3]
Next, the effect by the difference in the method of garbage processing process S31 in 4th Embodiment was verified. In the method of FIG. 6 (A), it was left for 6 days. On the other hand, in the method of FIG. 6 (B), the operations of adding food waste, spraying the surface of the lactic acid bacteria culture solution, and placing a weight stone were repeated for 6 days. After 6 days, both the garbage were crushed and the organic acid was measured. As a result, in the method of FIG. 6 (A), it was found that the lactic acid concentration was 23,030 mg / l and the acetic acid concentration was 3,280 mg / l, both of which were very high and the glucose recovery rate was lowered accordingly. In contrast, the lactic acid concentration in the method of FIG. 6B was 10,490 mg / l, and the acetic acid concentration was 2,190 mg / l. Moreover, in another sample, it was 11,800 mg / l and 2,950 mg / l, and it was falling compared with the system of FIG. 6 (A). As described above, in the garbage processing step S31, it was found that the method of FIG. 6B, in which the garbage is added every day and lactic acid bacteria are sprayed on the surface each time, is preferable.

[Example 4]
Next, the change in the glucose recovery rate due to the liquefaction treatment in the enzyme liquefaction step S32 in the fifth embodiment was examined. The holocellulose content in the polysaccharides of household garbage was about 30%.

  As Example 4, the above garbage was pulverized and then diluted 1.5 times with water. The diluted garbage was liquefied with an enzyme (80 ° C., 30 minutes) and then subjected to enzymatic saccharification (60 ° C., 2 hours). The combined use of glucoamylase N-40 and the cellulase enzyme agent XL531 improved the glucose recovery rate to 83%. The results are shown in Table 1 (Test 3). As a result of examining the optimum temperature for enzyme liquefaction, the glucose recovery rate was improved to 86% under the conditions of 85 ° C. and 30 minutes (see Table 1, Test 4). Furthermore, the addition amount of glucoamylase N-40 and the cellulase enzyme agent XL531 was examined under the conditions of Test 4. The amount of N-40 added was reduced to 1/4 or less, and XL531 was reduced to half.

  In addition, after pulverization, the above-mentioned garbage diluted 1.5 times was subjected to an enzyme saccharification test (used enzyme: Nagase enzyme, glucoamylase N-40, 60 ° C., 2 hours), and the glucose recovery rate was 62%. there were. Cellulase enzyme agent XL531 was used instead of glucoamylase N-40, but the glucose recovery rate was still 71%. When glucoamylase N-40 and cellulase enzyme agent XL531 were used in combination, the glucose recovery rate was improved to 77%, but the glucose recovery rate was still low (see Tests 1 and 2 in Table 1).

  By the way, about the co-op residue (business-type garbage) whose holocellulose content in the polysaccharide is about 3%, this food waste was pulverized and then diluted 1.5 times, and a saccharification test was conducted under the same conditions as in Comparative Example 4. As a result, the glucose recovery rate was 82 to 86%.

  From the above, it was found that in the case of household garbage with a high holocellulose content, the glucose recovery rate can be improved by liquefying the enzyme at a temperature of 85 ° C. and then performing enzymatic saccharification. In Example 4, in order to improve the dispersibility of the enzyme, it was intentionally diluted 1.5 times, but the same effect can be obtained without dilution.

Based on the above results, a fermentation test was performed by the following process.
Cultivation of household-type garbage that has been kept fresh → Enzyme liquefaction → Simultaneous saccharification / fermentation As a result, the concentration of produced ethanol was 20.5 to 21 g / kg (garbage). A high fermentation yield of about 85% was obtained with respect to the amount of ethanol calculated from the sugar contained in the garbage. It should be noted that the concentration of starch and holocellulose in terms of glucose in the wet garbage is 48 g / kg (garbage), and the theoretical ethanol production amount = 48 g / kg × (92/180) = 24.5 g / kg.

  From the above, it can be seen that even in household food waste, a high ethanol yield can be achieved by saccharification and fermentation in combination with cellulase and glucoamylase after liquefaction with enzyme (temperature: 85 ° C., 30 minutes). It was.

  The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, the structure and material of each element described in the above embodiments and examples, or the method and conditions of saccharification / fermentation are not limited, and may be other structures and materials, or other methods and It is good also as conditions.

It is a block diagram showing the structure of the alcohol production system which concerns on the 1st Embodiment of this invention. It is a block diagram showing the structure of the 2nd fermentation part shown in FIG. It is a figure for demonstrating the energy balance of the alcohol production system shown in FIG. It is a block diagram showing the structure of the alcohol production system which concerns on the 3rd Embodiment of this invention. It is a figure showing the flow of the alcohol production method which concerns on the 4th Embodiment of this invention. It is a figure for demonstrating the garbage processing process shown in FIG. It is a figure showing the flow of the alcohol production method which concerns on the 5th Embodiment of this invention. It is a characteristic view showing the relationship of the density | concentration of the organic acid with respect to the reaction time of Example 1, 2 and Comparative Example 1,2. It is a characteristic view showing the relationship of the density | concentration of the produced | generated ethanol with respect to reaction time of Example 1, 2 and Comparative Example 1,2. FIG. 3 is a characteristic diagram showing the daily change of the organic acid concentration in Example 1. FIG. 6 is a characteristic diagram showing the daily change of the organic acid concentration in Comparative Example 1. FIG. 6 is a characteristic diagram showing changes with time in the organic acid concentration of Example 2. FIG. 6 is a characteristic diagram illustrating changes with time in the organic acid concentration of Comparative Example 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Alcohol production system, 10 ... Alcohol production part, 11 ... Saccharification / 1st fermentation part, 12 ... Distillation part, 13 ... Dehydration part, 14 ... Yeast supply part, 20 ... Residue processing and utilization part, 21 ... 2nd fermentation Part, 21A ... methane fermentation tank, 21B ... water tank, 22 ... cogeneration part, 23 ... drying part

Claims (22)

An alcohol production system comprising a saccharification / first fermentation unit for saccharifying solid garbage to produce a saccharified product and subjecting the generated saccharified product to alcohol fermentation. The alcohol production system according to claim 1, wherein the saccharification / first fermentation unit simultaneously performs saccharification of raw garbage and alcohol fermentation. The alcohol production system according to claim 1 or 2, wherein a part of the koji produced in the saccharification / first fermentation section is used for the next alcohol fermentation. The alcohol production system according to claim 1 or 2, wherein a part of the koji produced in the saccharification / first fermentation unit is returned to the beginning of the saccharification / first fermentation unit. The alcohol production system according to any one of claims 1 to 4, further comprising a yeast supply unit that cultivates yeast and continuously or intermittently supplies the yeast to the saccharification / first fermentation unit. A distillation part for distilling the koji produced by the saccharification / first fermentation part and separating it into a crude alcohol and a distillation residue;
The alcohol production system according to any one of claims 1 to 5, further comprising: a dehydrating unit that dehydrates the crude alcohol to generate alcohol. A second fermentation unit for methane fermentation of the distillation residue discharged from the distillation unit;
The alcohol production system according to claim 6, further comprising: a drying unit that dries the digestion residue discharged from the second fermentation unit. The alcohol production system according to claim 7, wherein the biogas generated in the second fermentation unit is used as an energy source of at least one of the distillation unit and the drying unit. The second fermentation unit has a methane fermentation tank capable of introducing air, and reduces the concentration of hydrogen sulfide in the biogas by bringing the biogas generated in the methane fermentation tank into contact with air. The alcohol production system according to claim 7 or 8, wherein: The second fermentation unit has a water tank in the subsequent stage of the methane fermentation tank, and oxidizes hydrogen sulfide by circulating a mixed gas of the biogas and air between the methane fermentation tank and the water tank. The alcohol production system according to claim 9, wherein the concentration of hydrogen sulfide in the mixed gas is further reduced by using sulfur or sulfate ions. When the said garbage contains 10% or more of holocellulose in a polysaccharide, the said garbage is liquefied by a liquefying enzyme before saccharification in the saccharification / first fermentation part. The alcohol production system according to any one of 1 to 10. The alcohol production system according to claim 11, wherein at least one of glucoamylase and cellulase is used as the saccharifying enzyme. A method for producing alcohol, comprising a saccharification / first fermentation step in which solid waste is saccharified to produce a saccharified product, and the produced saccharified product is used for alcohol fermentation. 14. The alcohol production method according to claim 13, wherein in the saccharification / first fermentation step, saccharification of garbage and alcohol fermentation are simultaneously performed. The alcohol production method according to claim 13 or 14, wherein a part of the koji produced in the saccharification / first fermentation step is used for the next alcohol fermentation. The alcohol production method according to claim 13 or 14, wherein a part of the koji produced in the saccharification / first fermentation step is returned to the beginning of the saccharification / first fermentation step. The alcohol production method according to any one of claims 13 to 16, wherein yeast is cultured and supplied to the saccharification / first fermentation step continuously or intermittently. A distillation step of distilling the koji produced by the saccharification / first fermentation step to separate into crude alcohol and distillation residue;
The alcohol production method according to any one of claims 13 to 17, further comprising: a dehydration step of dehydrating the crude alcohol to produce alcohol. A second fermentation step of methane fermentation of the distillation residue discharged from the distillation step;
The alcohol production method according to claim 18, further comprising: a drying step of drying the digestion residue discharged from the second fermentation step. The alcohol production method according to claim 19, wherein the biogas generated in the second fermentation step is used as an energy source of at least one of the distillation step and the drying step. When the said garbage contains 10% or more of holocellulose in a polysaccharide, the said garbage is liquefied by a liquefying enzyme before saccharification in the saccharification / first fermentation step. The alcohol production method according to any one of 13 to 20. The alcohol production method according to claim 21, wherein at least one of glucoamylase and cellulase is used as the saccharifying enzyme.

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