Dry methane fermentation tank, dry methane fermentation system, and dry methane fermentation method

Abstract

To provide a dry methane fermentation tank which has a simple constitution, is easily maintained, and can sufficiently ferment a material to be fermented, a dry methane fermentation system equipped with the dry methane fermentation tank, and a dry methane fermentation method.SOLUTION: A dry methane fermentation tank comprising: a fermenter body for storing an organic resource and / or a raw material derived from the organic resource in a storage space and performing dry methane fermentation; an inlet port which is provided in the fermenter body and through which the organic resource and / or the raw material derived from the organic resource is charged into the fermenter body; The dry methane fermentation tank has a discharge port for discharging the fermentation residue of the organic resources and / or the organic resource-derived raw material from the dry methane fermentation tank body, and a conveyor device for carrying the organic resources and / or the organic resource-derived raw material charged from the charge port and transferring the organic resources toward the discharge port side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a dry methane fermentation tank, a dry methane fermentation system, and a dry methane fermentation method. [Background technology]

[0002] In order to make effective use of limited resources and create a prosperous society, solutions to many social issues, such as preventing global warming and ensuring a stable energy supply, are being considered. Among these social issues, waste disposal has become one of the most important themes to be resolved in recent years. Organic waste, including food waste, agricultural, forestry, and fishery products, and livestock waste, exceeds 200 million tons per year. Burying this waste requires a vast amount of land, and incineration is extremely costly.

[0003] Methane fermentation technology is a technology that uses methanogens to treat organic matter to produce biogas containing useful gases such as methane and hydrogen. Methane and hydrogen can be used as energy by burning them, and are also useful as raw materials for chemicals. By applying this type of methane fermentation technology to organic waste, it is possible to convert the waste into a useful resource, thereby reducing the burden associated with disposal and the carbon dioxide emissions associated with incineration. Furthermore, if methane fermentation is carried out near the site where the organic waste is generated, it becomes possible to produce and consume resources locally, eliminating the costs and burden associated with transporting the organic waste and the resources obtained.

[0004] This methane fermentation technology includes wet methane fermentation, which performs methane fermentation at a relatively low solid concentration, for example, 10% or less, and dry methane fermentation, which performs methane fermentation at a relatively high solid concentration, for example, 15% to 45%.

[0005] Wet methane fermentation has the advantage of simple equipment and low maintenance costs, but has disadvantages such as lower gas production compared to dry methane fermentation, a large amount of wastewater and high treatment costs.On the other hand, dry methane fermentation produces a large amount of biogas, but has disadvantages such as high power consumption and relatively complex equipment.

[0006] Incidentally, batch-type fermenters and continuous-type fermenters are known as methane fermentation tanks for performing methane fermentation. In a batch-type methane fermentation tank, a certain amount of fermentation material is introduced into the fermentation tank, and after fermentation, the residue of the fermentation material is recovered. Such a batch-type methane fermentation tank has the advantage of a simple device configuration and easy management of the fermentation material for each batch. On the other hand, when a batch-type methane fermentation tank is used, it is not possible to process a large number of fermentation materials at the same time, and in order to process a large number of fermentation materials, multiple fermentation tanks must be prepared.

[0007] In a continuous methane fermenter, the fermented material can be continuously or sequentially introduced into the same fermenter, and the fermented material is continuously fermented by passing it through the fermenter in the direction of flow. Because continuous methane fermentation is possible, continuous methane fermenter tanks have superior methane fermentation efficiency compared to batch-type methane fermenter tanks. Meanwhile, continuous methane fermenter tanks typically have an agitator installed inside the tank. This agitator transports the fermented material within the fermenter from the inlet to the outlet, and also agitates the fermented material, thereby improving fermentation efficiency. Patent Document 1 discloses a fermenter that is formed in a horizontally elongated cylindrical shape and incorporates a horizontal rotating shaft equipped with multiple agitation arms. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2022-44171 Summary of the Invention [Problem to be solved by the invention]

[0009] As mentioned above, continuous methane fermentation tanks are highly efficient at methane fermentation. On the other hand, dry methane fermentation usually requires the installation of an agitator in the tank to agitate and transport the fermented material. Such an agitator is important in dry methane fermentation, where the fermented material has a high solids concentration. However, agitating a fermented material with a high solids concentration requires a large amount of power, which places a heavy load on the agitator continuously. For this reason, agitators are prone to breakdowns with continued use, and regular maintenance of the agitator is necessary.

[0010] Furthermore, when agitation is performed, the fermented material at a certain point is mixed with the fermented material before and after it in the direction of flow, making it difficult to strictly control the fermentation time of the fermented material from the time it is added until it is discharged. That is, due to agitation, some of the fermented material that has not undergone sufficient fermentation is transported to the discharge port and discharged.

[0011] Therefore, an object of the present invention is to provide a dry methane fermentation tank that has a simple configuration, is easy to maintain, and is capable of sufficiently fermenting the fermentation target material, a dry methane fermentation system equipped with the dry methane fermentation tank, and a dry methane fermentation method. [Means for solving the problem]

[0012] As a result of intensive research to achieve the above-mentioned object, the inventors discovered that by using a conveyor device to transport the fermented material while performing methane fermentation, it is possible to sufficiently ferment the fermented material with a simple configuration without installing a mechanical stirring device, and as a result of further research, they arrived at the present invention.

[0013] The gist of the present invention is as follows. [1] A fermentation tank body for storing organic resources and / or organic resource-derived raw materials in a storage space and performing dry methane fermentation; an inlet provided in the fermenter body for introducing the organic resource and / or the organic resource-derived raw material into the fermenter body; a discharge port provided in the fermenter body for discharging the fermentation residue of the organic resource and / or the organic resource-derived raw material from the fermenter body; a conveyor device that carries the organic resource and / or the organic resource-derived raw material fed through the feed port and transports the organic resource toward the discharge port. [2] The dry methane fermenter according to [1], wherein the conveyor device includes a belt conveyor. [3] The dry methane fermenter according to [1], further comprising a fluid discharge nozzle attached to the fermenter body for discharging a fluid toward the accommodation space. [4] The dry methane fermenter according to [3], wherein the fluid discharge nozzle discharges a fluid toward the organic resource and / or the organic resource-derived raw material carried by the conveyor device. [5] The dry methane fermenter according to [1], further comprising a temperature control device arranged on the storage space side of the fermenter body to control the temperature within the storage space. [6] A dry methane fermentation system comprising the dry methane fermenter according to any one of [1] to [5]. [7] The present invention further includes an acid-producing fermenter that ferments an organic resource in the presence of an acid-producing bacterium to produce a primary fermentation product of the organic resource and a gas containing hydrogen and carbon dioxide; The dry methane fermentation system according to [6], wherein the dry methane fermentation tank is a fermentation tank that accommodates the primary fermentation product and performs dry methane fermentation. [8] The dry methane fermentation system according to [7], further comprising a hydrogen-utilizing fermenter that accommodates the gas produced in the acid-producing fermenter and ferments it with hydrogen-utilizing methanogens. [9] The dry methane fermentation system according to [8], wherein the hydrogen-utilizing fermenter contains a porous inorganic medium.

[10] Further, a kneading and blasting machine is provided for kneading and blasting organic resources to produce pulverized organic resources; The kneading and explosion crusher has a housing having a cylindrical space and an Archimedes screw disposed in the space, The housing has an inlet for introducing the organic resource at one cylindrical end side of the space, and an outlet for removing the pulverized organic resource at the other cylindrical end side of the space, The dry methane fermentation system according to [6], wherein the pitch of the Archimedes screw gradually decreases from the inlet to the outlet.

[11] Further, an acetic acid utilization fermentation tank is provided in which acetic acid utilization methanogens are used to produce a fermentation product containing acetic acid from the gas and liquid generated from the organic resource in the kneading and explosion machine, The dry methane fermentation system according to

[10] , wherein the fermented product containing acetic acid is subjected to dry methane fermentation in the dry methane fermenter.

[12] A dry methane fermentation method comprising a step of performing dry methane fermentation of an organic resource and / or a raw material derived from the organic resource using the dry methane fermenter described in any one of [1] to [5]. [Effects of the Invention]

[0014] As described above, according to the present invention, it is possible to provide a dry methane fermentation tank that has a simple configuration, is easy to maintain, and is capable of sufficiently fermenting the fermentation target material, a dry methane fermentation system equipped with the dry methane fermentation tank, and a dry methane fermentation method. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram for explaining the process of decomposition of organic resources by methane fermentation. [Figure 2] FIG. 2 is a schematic vertical cross-sectional view showing a dry methane fermenter according to one embodiment of the present invention. [Figure 3] FIG. 3 is a configuration diagram of a dry methane fermentation system according to one embodiment of the present invention. [Figure 4] FIG. 4 is a longitudinal cross-sectional view of a kneading and explosion machine provided in the dry methane fermentation system shown in FIG. [Figure 5] FIG. 5 is a cross-sectional view in the width direction of the kneading and explosion crusher shown in FIG. [Figure 6]FIG. 6 is a perspective view showing the vicinity of the outlet of the kneading and explosion crusher shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, preferred embodiments of the dry methane fermentation tank, the dry methane fermentation system, and the dry methane fermentation method according to the present invention will be described in detail with reference to the drawings.

[0017] <1. Principle of dry methane fermentation> Prior to describing preferred embodiments of the present invention, an outline of general methane fermentation will be first described. Figure 1 is a schematic diagram for explaining the process of decomposition of organic resources in methane fermentation.

[0018] Methane fermentation is a method of fermenting organic resources derived from living organisms under anaerobic conditions, recovering the fermentation heat and methane gas, and using them as energy or chemical raw materials. Organic resources generally come from waste materials that have no other uses, such as livestock waste and food waste.

[0019] Organic resources are usually composed of polymeric organic matter, which can be broadly classified into proteins, lipids, carbohydrates, etc. As shown in Figure 1, these polymeric organic matter are broken down by hydrolytic microorganisms into their constituent units, amino acids, glycerin and fatty acids, and low-molecular-weight organic matter such as sugars (e.g., glucose) (catabolic reaction (1)).

[0020] Next, the hydrolyzed low-molecular-weight organic matter is decomposed into volatile fatty acids (VFAs) such as propionic acid, butyric acid, and isobutyric acid by the oxidative action of acid-producing bacteria (catabolic reaction (2)).The volatile fatty acids are then decomposed into hydrogen, carbon dioxide, acetic acid, and other substances by syntrophic acetogenic bacteria (catabolic reaction (3)).

[0021] Methanogenic archaea use this hydrogen, carbon dioxide, and acetic acid as energy sources to produce methane (catabolic reactions (4) and (5)). Specifically, acetic acid is broken down into methane (CH4) and carbon dioxide (CO2) by acetic acid-utilizing methanogenic bacteria in the reaction shown below (Equation 1) (catabolic reaction (4)). Hydrogen reacts with carbon dioxide (CO2) by hydrogen-utilizing methanogenic bacteria in the reaction shown below (Equation 2), producing methane (CH4) and water (H2O) (catabolic reaction (5)).

[0022] (Formula 1) CH3COOH→CH4+CO2 (Formula 2) 4H2+CO2→CH4+2H2O

[0023] Gas containing CH4 and CO2 produced by decomposition of organic matter is called "biogas." Biogas obtained from a generally managed methane fermentation tank is composed of, for example, approximately 55% to 60% by mass of methane, approximately 35% to 40% by mass of carbon dioxide, approximately 2% by mass of hydrogen sulfide, 2% by mass or less of nitrogen, 2% by mass or less of oxygen, and 1% by mass or less of hydrogen.

[0024] As mentioned above, the microbial community in a methane fermentation tank generally consists of a bacterial community that decomposes high molecular weight organic matter and a methanogenic archaea community that produces methane. Usually, methane fermentation is carried out using a single methane fermentation tank, so the above reactions occur simultaneously in the single methane fermentation tank.

[0025] There are two known types of methane fermentation: thermophilic methane fermentation, in which the decomposition rate accelerates at approximately 55°C, and mesophilic methane fermentation, in which the decomposition rate accelerates at approximately 35°C. Because thermophilic methane fermentation decomposes organic matter faster than mesophilic methane fermentation, it can recover approximately two to four times as much biogas as mesophilic methane fermentation. High temperatures are also expected to be effective in killing pathogenic bacteria. However, thermophilic methane fermentation requires a greater amount of heat energy to maintain the equipment compared to mesophilic methane fermentation.

[0026] High temperatures are expected to be effective in killing pathogenic bacteria, so up until now, most research aimed at killing pathogenic bacteria has used high-temperature treatment for methane fermentation. However, this has the disadvantage of requiring a large amount of heat energy to maintain the facility, so most methane fermentation facilities currently use mesophilic methane fermentation.

[0027] Furthermore, the fermentation residue discharged after methane fermentation contains fertilizer components such as inorganic and organic nitrogen (N), phosphorus (P), and potassium (K), making it possible to use the fermentation residue as fertilizer for crop cultivation.

[0028] <2. Dry methane fermentation tank> Next, a dry methane fermentation tank according to a preferred embodiment of the present invention will be described. Fig. 2 is a schematic vertical cross-sectional view showing a dry methane fermentation tank according to one embodiment of the present invention. In the drawing, the size of each component is appropriately exaggerated for ease of explanation, and the actual proportions and sizes of each component are not shown.

[0029] The dry methane fermenter 100 shown in Fig. 2 is a tank for storing an organic resource 300 and / or its processed product (organic-resource-derived raw material) and performing dry methane fermentation. The dry methane fermenter 100 is a continuous methane fermenter into which the organic resource 300 can be continuously introduced and in which dry methane fermentation is continuously performed. The dry methane fermenter 100 has a fermenter main body 110, a conveyor device 120, an inlet 130, a discharge section 140, a biogas recovery nozzle 150, fluid discharge nozzles 160A and 160B, and a heating device 170. Note that the object to be subjected to methane fermentation treatment (fermented material) in the dry methane fermenter 100 may be either the organic resource 300 or raw materials derived therefrom (organic-resource-derived raw material, processed product), or both. However, in the following explanation, only the organic resource 300 will be described as a representative example for ease of explanation.

[0030] The fermenter main body 110 is a roughly rectangular parallelepiped container, and is a horizontal fermenter that is long in the horizontal direction. The fermenter main body 110 is a fermenter for fermenting a fermentation target such as organic resource 300, and also serves as a storage container for storing various devices. The fermenter main body 110 has a storage space 111 for storing a fermentation target such as organic resource 300 and various devices such as a conveyor device 120.

[0031] The fermenter main body 110 can be constructed by arranging necessary components in, for example, a substantially rectangular parallelepiped metal container, etc. For example, an inlet 130 is provided at one end of the fermenter main body 110 in the longitudinal direction, and an outlet 140 is provided at the other end.

[0032] A conveyor device 120 is disposed in the accommodation space 111 of the fermenter main body 110 along the longitudinal direction of the fermenter main body 110, from the inlet 130 side toward the discharge section 140 side. In this embodiment, the conveyor device 120 is a belt conveyor, and includes a conveyor belt 121, a power roll 123, and support rolls 125 and 127.

[0033] The conveyor belt 121 is a water-impermeable belt on the surface of which the organic resource 300 can be placed. The conveyor belt 121 can be an endless belt made of resin reinforced with reinforcing fibers, for example.

[0034] The conveyor belt 121 is supported by the above-mentioned power roll 123 and support rolls 125 and 127. The power roll 123 is a roll arranged on the discharge section 140 side, and is configured to be rotatable by a drive device (not shown), and rotates to rotate the conveyor belt 121. The support roll 125 is arranged on the inlet 130 side, and multiple support rolls 127 are arranged between the support roll 125 and the power roll 123.

[0035] The conveyor device 120 receives and carries the organic resource 300 input from the input port 130 on the input port 130 side of the conveyor belt 121, and transports it toward the discharge section 140 by rotating the conveyor belt 121 (arrow B in the figure). Here, dry methane fermentation of the organic resource 300 occurs during transportation. Therefore, the time during which the organic resource 300 is supported and transported on the conveyor belt 121 can be said to be the time for dry methane fermentation, and the rotation speed and timing of the conveyor belt 121 are set in accordance with the fermentation time.

[0036] When the organic resource 300 reaches the vicinity of the discharge section 140, the rotation of the power roll 123 causes the conveyor belt 121 to turn around and rotate, causing the organic resource 300 to fall from the conveyor belt 121 and be delivered to the discharge space 143 of the discharge section 140.

[0037] The inlet 130 is a gate for introducing organic resources 300, which have been transported from an upstream device of the dry methane fermenter 100, into the fermenter body 110 of the dry methane fermenter 100. The inlet 130 is a so-called slide gate, and a gate blade 131 slides by the power of an actuator 133 to open and close the inlet 130. This allows the organic resources 300 to be introduced into the dry methane fermenter 100 through the inlet 130 (arrow A).

[0038] Discharge section 140 is disposed on the opposite side of fermenter body 110 from inlet 130. Discharge section 140 has cover 141, discharge space 143, discharge port 145, and transfer pipe 147.

[0039] The cover 141 is connected to the open end of the fermenter body 110 and covers the end while forming a discharge space 143 that is continuous with the accommodation space 111 of the fermenter body 110. The discharge space 143 formed by the cover 141 also functions as a storage space that stores the fermentation residue of the organic resource 300 that has undergone fermentation, with the discharge outlet 145 at its bottom.

[0040] The discharge outlet 145 is a gate for discharging the fermentation residue of the organic resource 300 stored in the discharge space 143 to outside the dry methane fermenter 100. The discharge outlet 145 is a so-called slide gate, and a gate blade 1451 slides by the power of an actuator 1453 to open and close the discharge outlet 145. As a result, the fermentation residue of the organic resource 300 is discharged to outside the dry methane fermenter 100 through the discharge outlet 145 and transferred to a downstream device via a transfer pipe 147.

[0041] The biogas recovery nozzle 150 is attached to the top of the fermenter main body 110. The biogas recovery nozzle 150 is a nozzle for recovering biogas produced by dry methane fermentation carried out in the dry methane fermenter 100. The biogas recovery nozzle 150 is connected to a transfer pipe (not shown), and the biogas recovered from the dry methane fermenter 100 via the biogas recovery nozzle 150 is transported via the transfer pipe to the gas storage tank 23 (described later).

[0042] The fluid discharge nozzles 160A and 160B are attached to the upper part of the fermenter main body 110 along the transport path of the organic resource 300 during dry methane fermentation, that is, along the conveyor belt 121 of the conveyor device 120.

[0043] The fluid discharge nozzles 160A, 160B discharge a fluid, i.e., a composition mainly containing gas and / or liquid, toward the storage space 111. In this embodiment, specifically, the fluid discharge nozzles 160A, 160B spray the fluid toward the organic resource 300 in the storage space 111. This enables gentle stirring of the organic resource 300. The inventors have found that in the dry methane fermenter 100 of this embodiment, gentle stirring of the organic resource 300 is possible by discharging the fluid from the fluid discharge nozzles 160A, 160B, even without forcibly performing mechanical stirring using a stirring blade or the like. This is presumably because the organic resource 300 supported by the conveyor device 120 has a large excess space within the storage space 111 of the fermenter main body 110 due to its configuration, which allows circulation of airflow and liquid by discharging the fluid, thereby enabling stirring.

[0044] Any fluid may be discharged from the fluid discharge nozzles 160A, 160B, but it is preferable to use, for example, gas and / or liquid generated when the organic resource 300 is treated in an upstream device before the dry methane fermenter 100. This allows the composition released from the organic resource 300 to be effectively used in dry methane fermentation. Furthermore, the gas and / or liquid generated when the organic resource 300 is treated has a specific composition depending on the treatment, and by selecting the timing of release, it is possible to improve the yield of biogas and the fermentation efficiency of dry methane fermentation.

[0045] The heating device 170 is attached to the upper part of the inside (accommodation space 111 side) of the fermenter main body 110, in contact with the accommodation space 111. The heating device 170 controls the fermentation temperature in dry methane fermentation by heating the accommodation space 111 of the fermenter main body 110 and, ultimately, the organic resource 300. In conventional dry methane fermenters, the organic resource is densely packed, so if a heating device were to be placed inside the fermenter, the organic resource would interfere with the heating device, making such placement difficult. Therefore, in conventional dry methane fermenters, when a heating device is placed inside the fermenter, it is attached to the outside of the fermenter to indirectly heat the inside of the fermenter. However, in this case, part of the heat generated by the heating device is released to the outside, making it impossible to effectively input heat into the inside of the fermenter. On the other hand, in this embodiment, there is a large amount of excess space within the accommodation space 111 of the fermenter main body 110, so that the heating device 170 can be easily placed on the accommodation space 111 side of the fermenter main body 110 without interfering with the organic resource 300, and the heat from the heating device 170 can be effectively used for dry methane fermentation.

[0046] Furthermore, the heating device 170 can generate heat by any mechanism, and can be, for example, an electric heating system (resistance heating system), an electromagnetic heating system such as a microwave heating system, a combustion heating system, a heat pump heating system, etc. Furthermore, the heating device 170 may heat the inside of the fermenter body 110 by passing a fluid such as a liquid or gas as a heat medium through a flow path arranged in the fermenter body 110, or may generate heat directly within the fermenter body 110 and heat the inside of the fermenter body 110 with the generated heat.

[0047] Furthermore, the dry methane fermenter 100 may be equipped with a pressure gauge, a thermometer, etc. as necessary. Furthermore, each dry methane fermenter 100 may be configured so that a target microorganism group can be added from outside.

[0048] In the dry methane fermentation tank 100 described above, the organic resource 300 introduced through the introduction port 130 is carried by the conveyor belt 121 of the conveyor device 120. The organic resource 300 carried by the conveyor belt 121 is then transported toward the discharge port 145 in the fermentation tank main body 110 of the dry methane fermentation tank 100, where it undergoes dry methane fermentation. When the organic resource 300, which has become a fermentation residue after dry methane fermentation, reaches the end of the conveyor device 120 on the discharge port 145 side, it is transferred from the conveyor belt 121 to the discharge space 143 of the discharge section 140. The organic resource 300 is then discharged from the discharge port 145 to the outside of the dry methane fermentation tank 100. Meanwhile, biogas generated during dry methane fermentation is transported to the outside of the dry methane fermentation tank 100 via the biogas recovery nozzle 150.

[0049] <3. Dry methane fermentation system> Next, a dry methane fermentation system according to a preferred embodiment of the present invention will be described. Fig. 3 is a configuration diagram of a dry methane fermentation system according to one embodiment of the present invention, Fig. 4 is a longitudinal cross-sectional view of a kneading and exploding machine provided in the dry methane fermentation system shown in Fig. 3, Fig. 5 is a width-wise cross-sectional view of the kneading and exploding machine shown in Fig. 4, and Fig. 6 is a perspective view showing the vicinity of the outlet of the kneading and exploding machine shown in Fig. 4. In the figures, the size of each component is appropriately exaggerated for ease of explanation, and the actual proportions and sizes of each component are not shown.

[0050] The dry methane fermentation system 1 shown in FIG. 3 is an apparatus for fermenting an organic resource 300 by dry methane fermentation to obtain biogas containing methane.

[0051] Examples of organic resources 300 used in this embodiment include household garbage (e.g., food waste), household waste such as paper waste, animal waste such as sewage sludge and livestock manure, wood waste (e.g., waste wood, sawdust, parks, packaging waste, board scraps, waste chips, felled wood (thinned wood, etc.), pruned branches, and stumps), crop residues (picked leaves, fruit, cut grass, etc.), and plant waste such as waste mushroom beds. Only one of these may be used as organic resource 300, or two or more may be combined and used as organic resource 300.

[0052] The dry methane fermentation system 1 includes a crusher 11, a kneading and explosion machine 200, a kneader 13, an acid-producing fermenter 15, a hydrogen-utilizing fermenter 17, an acetic acid-utilizing fermenter 19, a dry methane fermenter 100, a desulfurization device 21, a gas storage tank 23, and a return culture tank 27.

[0053] The crusher 11 crushes the organic resource 300 into pieces of an appropriate size. Examples of the crusher 11 include a cutting chipper, a cutter knife chipper, a hammer crusher, a chain crusher, a single-shaft crusher, and a multi-shaft crusher (e.g., a biaxial crusher), and one of these can be used alone or two or more can be used in combination. The organic resource 300 crushed in the crusher 11 is transferred to the kneading / explosion crusher 200. Note that if only organic resources 300 that are already of an appropriate size are used, the crusher 11 can be omitted.

[0054] The kneading and explosion crusher 200 kneads and explodes an organic resource 300 to produce pulverized organic resource material. The kneading and explosion crusher 200 will be described below with reference to Figures 4 to 6. As shown in Figure 4, the kneading and explosion crusher 200 includes a housing 210, an archimedes screw 220, an outlet 230, a side blade 240, an outlet-side blade 250, and a water pipe 260.

[0055] The housing 210 is a casing of the kneading and explosion-crushing machine 200, and includes a cylindrical housing body 211. The housing body 211 forms a cylindrical space 213 in which the Archimedes screw 220 and the like are housed. An opening serving as an inlet is provided above the base end of the housing body 211, and a hopper 215 for charging the organic resource 300 is connected to the opening.

[0056] As described above, the archimedian screw 220 is disposed in the cylindrical space 213 formed by the housing body 211, with its longitudinal direction aligned with the axial direction of the space 213. The archimedian screw 220 has its tip 221 inserted into a bearing 233 of the outlet 230 and rotatably fixed thereto. On the other hand, a driving source 270 for rotating the archimedian screw 220 is connected to the base end 223.

[0057] The Archimedes screw 220 also has a spiral screw blade 225 that runs along its axial direction. As shown in Fig. 5, when viewed perpendicularly to its axis, the screw blade 225 has a circular periphery that corresponds to the inner surface formed by the housing body 211 of the housing 210, and the circle has a diameter that is close to the side blade 240, which will be described later. As the Archimedes screw 220 rotates, the organic resource 300 stored in the space 213 of the housing body 211 is transported toward the outlet 230 as the screw blade 225 rotates and pushes the organic resource 300.

[0058] 4, the helical pitch of the screw blade 225 gradually decreases from the inlet to the outlet 230. Therefore, when the organic resource 300 is transported by the Archimedes screw 220, a pressure corresponding to the pitch of the screw blade 225 is applied to the organic resource 300.

[0059] The pitch of the screw blades 225 of the Archimedes screw 220 is the smallest P MIN The one closest to the inlet has the largest P MAXHere, the pitch P on the outlet side MIN is the pitch P on the inlet side MAX The ratio can be 5.0% or more and 70% or less, and preferably 10% or more and 50% or less, of the total mass of the organic resource 300. This allows the organic resource 300 to be kneaded while being sufficiently compressed, and also allows the explosive action described below to be fully achieved.

[0060] The pitch of the Archimedes screw 220 is 2.5 x 10 5 Over 14.0 x 10 5 N / m 2 It is preferable that the pitch of the Archimedes screw 220 is adjusted so that a pressure of 4.0 × 10 or less is applied to the organic resource near the outlet. This allows the blasting effect described below to be sufficiently obtained, and the organic resource 300 to be sufficiently compressed. More preferably, the pitch of the Archimedes screw 220 is adjusted so that a pressure of 4.0 × 10 or less is applied to the organic resource near the outlet. 5 Over 12.0 x 10 5 N / m 2 The following pressures are applied:

[0061] 4 and 6, outlet 230 is disk-shaped and is attached to the tip side of housing body 211 of housing 210 so as to seal the cylinder formed by housing body 211. As shown in Fig. 6, outlet 230 has a plurality of through-holes 231, and pulverized organic resource 300 is pushed out from housing 210 to the outside through these through-holes 231. Furthermore, outlet 230 has a bearing 233 at its center that receives the shaft of archimedes screw 220.

[0062] A plurality of side blades 240 are arranged on the inner surface of the casing body 211 along the axial direction so as to surround the periphery of the archimedes screw 220. As shown in FIG. 5 , the side blades 240 are arranged so as to abut or be adjacent to the screw blades 225 of the archimedes screw 220. When the screw blades 225 rotate, the organic resource 300 introduced into the casing 210 rotates in the circumferential direction of the archimedes screw 220 and abuts against the side blades 240. The organic resource 300 is then further rotated by the archimedes screw 220, and is subjected to shearing force by the abutting side blades 240, thereby being sheared and ground. Furthermore, the side blades 240 act as baffles, stirring the organic resource 300.

[0063] The outlet-side blade 250 is attached to the tip side (the outlet side) of the archimedes screw 220. The outlet-side blade 250 is rotatable relative to the housing 210 together with the rotation of the archimedes screw 220. The outlet-side blade 250 cuts the organic resource 300 extruded from the outlet 230.

[0064] The water supply pipe 260 is a pipe that supplies water into the space 213 from the side of the housing 210. An on-off valve 261 is provided midway along the water supply pipe 260, and by operating this valve, it is possible to start and stop the supply of water into the space 213 and adjust the amount of water supplied. For example, excessive heat may be generated due to friction, compression, etc. of the organic resource 300 caused by the rotation of the Archimedes screw 220. In such cases, by supplying water through the water supply pipe 260, the water acts as a lubricant and can suppress excessive friction of the organic resource 300.

[0065] When the organic resource 300 is fed into the kneading and explosion crusher 200 described above and the Archimedes screw 220 rotates, the organic resource 300 is conveyed toward the outlet 230 while rotating. In this case, the organic resource 300 is subjected to shearing force due to the relative movement of the side blades 240 and the screw blade 225, and is crushed, ground, and kneaded. In addition, as the pitch of the screw blade 225 gradually decreases toward the outlet 230, the organic resource 300 is gradually compressed and heat is generated. As a result, the organic resource 300 softens due to the action of heat, accelerating the crushing, grinding, and kneading described above.

[0066] Then, near the outlet 230, the pressure is suddenly released, causing the organic resource 300 to expand, burst, and be exploded and released from the kneading and explosion crusher 200. Through the above-mentioned action, the organic resource 300 is pulverized into pulverized organic resource material.

[0067] The kneading and explosion action of the organic resource 300 by such a kneading and explosion machine 200 is particularly effective for fibrous organic resources 300, such as plant resources such as wood resources. Plant resources are mainly composed of fibers such as cellulose and hemicellulose. Fibers have high tensile strength and are difficult to defibrate by simple cutting. However, by pulverizing and grinding the organic resource 300 due to the rotation of the archimedes screw 220 and by blasting at the outlet 230, the fiber is sufficiently defibrated and refined, making it easier for microbial groups to come into contact with the fiber during fermentation.

[0068] In particular, wood resources, among plant resources, have lignin, a hard polymer, attached to the periphery of sugars such as cellulose that make up the fiber, and lignin inhibits the decomposition of sugars by microorganisms. On the other hand, lignin softens when heated. In the kneading and explosion machine 200, the organic resource 300 is kneaded and exploded while being heated, which softens the lignin attached to the fiber, facilitating the defibration of the fiber.

[0069] Furthermore, when the kneading and explosion-crushing machine 200 is used, the organic resource 300 is heated, and some of the moisture is released from the organic resource 300, becoming steam or a liquid separated from the solid matter of the organic resource 300. This makes it easier to adjust the moisture content in the subsequent kneader 13.

[0070] Furthermore, the organic resource 300 typically contains moisture. When pressurized and heated in the presence of moisture, some components of the organic resource 300 decompose and / or denature. For example, starch and protein are denatured by heating, making them susceptible to the action of enzymes released by the microorganisms during fermentation.

[0071] In particular, natural starch particles are generally not susceptible to enzymatic action in their original state. Specifically, starch particles are formed by regularly arranged molecules and are insoluble in water. Therefore, in this state, enzymes and starch molecules are less likely to bond, making them less susceptible to enzymatic action. Therefore, it is preferable to heat these starch particles together with water to gelatinize them and turn them into a gel. The gelatinized starch particles lose their regularity and water is absorbed into the starch molecules, making it easier for enzymes to penetrate into the starch molecules.

[0072] In addition, sugars such as modified starch, cellulose, and hemicellulose are also partially hydrolyzed and converted into monosaccharides such as glucose and various oligosaccharides with relatively small molecular weights. Furthermore, proteins are also partially hydrolyzed and reduced in molecular weight. In this process, organic acids present in the organic resource 300 act as acid catalysts for the hydrolysis. These decomposition products, such as monosaccharides, oligosaccharides, and amino acids, are soluble in water and are eluted from the organic resource 300.

[0073] In this way, decomposed and / or denatured components are generally susceptible to the action of enzymes released from the microbial community during fermentation, and are in a state where they are easily decomposed. Furthermore, even if the solubilized matter in the organic resource 300 has not been decomposed, it will dissolve in heated water.

[0074] As described above, when the kneading and explosion treatment is carried out by the kneading and explosion crusher 200, the organic resource 300 is pulverized and defibrated by crushing, grinding, and explosion, and at the same time, the organic resource 300 is kneaded. At the same time, the components in the organic resource 300 are denatured and decomposed. In this way, when the kneading and explosion treatment is carried out by the kneading and explosion crusher 200, the organic resource 300 is simultaneously subjected to physical and chemical effects, and is brought into a state in which it is easy to ferment.

[0075] Furthermore, among the components of the organic resource 300, components with relatively small molecular weights are dissolved in the moisture and steam released from the organic resource 300. That is, when the kneading and explosion treatment is performed by the kneading and explosion crusher 200, component separation is also performed at the same time.

[0076] The organic resource explosion product, which is mainly composed of solids, of the organic resource 300 that has been subjected to the kneading and explosion treatment is transported to the kneader 13. In addition, the released gas and liquid from the organic resource 300 are transported to the acetic acid assimilating fermenter 19.

[0077] The kneader 13 is a device that performs kneading to mix the pulverized organic resource material exploded in the kneading and explosion machine 200 with seed bacteria. Examples of the kneader 13 include a single-shaft mixer, a multi-shaft mixer (e.g., a two-shaft mixer), an open roll, a pressure kneader, an internal mixer, and a Banbury mixer, and one of these can be used alone or two or more can be used in combination. The pulverized organic resource material mixed with the seed bacteria in the kneader 13 is transferred to the acid-producing fermenter 15. Note that in this embodiment, reverting bacteria obtained as fermentation residue after dry methane fermentation is transferred and charged into the kneader 13 as seed bacteria.

[0078] The acid-producing fermenter 15 is a fermenter for performing primary fermentation on the pulverized organic resource mixed with the seed culture to produce a primary fermentation product and a gas containing hydrogen and carbon dioxide. In this embodiment, the primary fermentation in the acid-producing fermenter 15 decomposes the pulverized organic resource into volatile fatty acids (VFAs) such as propionic acid, butyric acid, and isobutyric acid.

[0079] The acid-producing fermenter 15 is configured to be sealable during primary fermentation, thereby ensuring an anaerobic environment during primary fermentation and preventing leakage of generated gaseous components such as hydrogen and carbon dioxide. The acid-producing fermenter 15 is also equipped with a pressure gauge, a thermometer, and a temperature control device, allowing for temperature control according to the conditions of primary fermentation. The acid-producing fermenter 15 may also be equipped with an appropriate stirring device to enable stirring of the pulverized organic resource material. The acid-producing fermenter 15 is also equipped with a pressure reducing valve, which allows the generated gaseous components to be transferred to the hydrogen-assimilating fermenter 17 when the pressure of the gaseous components reaches a predetermined level or higher.

[0080] The bacterial colony contained in the acid-producing fermenter 15 during primary fermentation is basically a complex microbial colony derived from the seed culture. Of the catabolic reactions shown in Figure 1, catabolic reactions (1) and (2) mainly occur in the acid-producing fermenter 15, and the organic resource 300, which is mainly composed of high molecular weight organic matter, is decomposed into a mixture containing volatile fatty acids via low molecular weight organic matter. In addition, gases containing hydrogen and carbon dioxide are produced as a result of the decomposition of high molecular weight organic matter into volatile fatty acids by primary fermentation.

[0081] Therefore, the complex microbial consortium that can be accommodated in the acid-producing fermenter 15 can include activated hydrolytic bacteria and acidogenic bacteria. Furthermore, since the catabolic reactions shown in Fig. 1 occur in parallel, the complex microbial consortium that can be accommodated in the acid-producing fermenter 15 can also include symbiotic acetogenic bacteria involved in the catabolic reaction (3) (e.g., acetate-oxidizing bacteria belonging to the order Thermotogales, which are thermophilic bacteria, and decomposing bacteria of the order Clostridiales, which decompose proteins and carbohydrates), and methanogenic archaea involved in the catabolic reactions (4) and (5) (hydrogen-utilizing methanogens, such as Methanoculleus thermopyilus, Methanobacteriaceae, and Methanothermaceae, as well as acetate-utilizing methanogens, such as Metyanosarcina thermophia).

[0082] Furthermore, if a predetermined pressure is exceeded, some of the gaseous components (hydrogen, carbon dioxide, steam, etc.) produced in the acid-producing fermenter 15 are transferred via a pressure reducing valve to the hydrogen-assimilation fermenter 17. The remainder of the primary fermentation product (a mixture of liquid and solid components) and gaseous components (hydrogen, carbon dioxide, steam, etc.) produced in the acid-producing fermenter 15 are transferred to the dry methane fermenter 100.

[0083] The hydrogen-assimilating fermenter 17 is a tank that stores the gas components (hydrogen, carbon dioxide, steam, etc.) generated in the acidogenic fermenter 15 and ferments them with hydrogen-assimilating bacteria. The hydrogen-assimilating bacteria use hydrogen and carbon dioxide as substrates in the hydrogen-assimilating fermenter 17 to produce methane. The microbial community that may be present in the hydrogen-assimilating fermenter 17 may include those that were present in the acidogenic fermenter 15, but the hydrogen-assimilating bacteria are particularly active. The stored gas components (hydrogen, carbon dioxide, steam, etc.) are then converted to methane by the catabolic reaction (5) shown in FIG. 1.

[0084] The hydrogen-assimilating fermenter 17 is configured to be sealable during fermentation, thereby ensuring an anaerobic environment during fermentation and preventing leakage of generated gases, such as methane. Furthermore, the hydrogen-assimilating fermenter 17 is equipped with a pressure gauge, a thermometer, and a temperature control device, allowing for temperature control according to the fermentation status. The hydrogen-assimilating fermenter 17 may also be equipped with an appropriate stirring device to allow stirring of the fermented product in the hydrogen-assimilating fermenter 17.

[0085] Furthermore, in this embodiment, the hydrogen-assimilating fermenter 17 includes a porous medium. By accommodating such a porous medium in the hydrogen-assimilating fermenter 17, a medium for the hydrogen-assimilating bacteria is ensured, and a sufficient reaction field for the methane production reaction by the hydrogen-assimilating methanogens is provided. In particular, since the substrate in the hydrogen-assimilating fermenter 17 is a gas, the contact interface between the hydrogen-assimilating bacteria and the substrate is generally limited. However, because the porous medium is porous, a sufficient contact interface between the hydrogen-assimilating bacteria and the substrate is provided, and fermentation is sufficiently promoted.

[0086] The porous medium may be in any shape, such as granular, plate-like, block-like, ring-like, ball-like, or pellet-like. Multiple porous mediums of different shapes may also be combined. Among the above-mentioned shapes, the porous medium is preferably granular, and therefore preferably contains porous granular material. Such porous granular material itself has a relatively large surface area, and pores resulting from the porosity are generated on the surface of the porous granular material, making it possible to obtain a larger contact interface compared to other shapes. Furthermore, when the porous medium contains porous granular material, stirring of the fermented material in the hydrogen-assimilating fermenter 17 is easy.

[0087] The porous medium may be made of any material, such as glass, ceramics, activated carbon, zeolite, humic substances, etc., and one of these may be used alone or two or more may be used in combination. The porous medium may be composed of either an organic material or an inorganic material, or may be composed of both. Preferably, the porous medium includes a porous inorganic medium. The porous inorganic medium is stable and does not affect fermentation.

[0088] Therefore, the porous medium preferably comprises porous inorganic granules, more preferably one or more selected from the group consisting of glass foam granules, zeolite granules, ceramic granules and activated carbon.

[0089] Among the above, glass foam granules have an appropriate pore size and water retention capacity, and are particularly suitable as a porous medium for the hydrogen assimilating fermenter 17, which requires a reaction at the gas-liquid interface.

[0090] The particle size of the porous granules described above, based on JIS Z8815-1994, is not particularly limited, but is, for example, 0.30 mm to 8.0 mm, preferably 0.50 mm to 6.0 mm, and more preferably 1.0 mm to 3.0 mm. When the particle size of the porous granules is within the above range, stirring of the fermented product in the hydrogen-assimilating fermenter 17 can be facilitated, and fermentation can be further promoted.

[0091] The fermented product (a mixture of liquid and solid components) and gas components (methane, water vapor, etc.) produced in the hydrogen assimilative fermenter 17 are transported to the dry methane fermenter 100 and released into the accommodation space 111 by the fluid release nozzle 160B.

[0092] The acetic acid-utilizing fermenter 19 is a tank that receives the gas and liquid released in the kneading and explosion-crushing machine 200 and produces a fermented product containing acetic acid by the acid-producing bacteria and symbiotic acetogenic bacteria. As described above, the gas and liquid released in the kneading and explosion-crushing machine 200 contain low-molecular-weight compounds such as relatively low-molecular-weight sugars (monosaccharides, oligosaccharides, etc.), low-molecular-weight peptides, and amino acids. Therefore, in the acetic acid-utilizing fermenter 19, the catabolic reactions (2) and (3) shown in FIG. 1 mainly proceed to decompose these compounds. The microbial communities that may be present in the acetic acid-utilizing fermenter 19 may include those that were present in the acid-producing fermenter 15, but the acid-producing bacteria and symbiotic acetogenic bacteria are particularly activated.

[0093] The acetic acid assimilating fermenter 19 is configured to be sealable during fermentation, thereby ensuring an anaerobic environment during fermentation and preventing leakage of generated gases, such as hydrogen and carbon dioxide. The acetic acid assimilating fermenter 19 is further equipped with a pressure gauge, a thermometer, and a temperature control device, allowing temperature control according to the fermentation status. The acetic acid assimilating fermenter 19 may also be equipped with an appropriate stirring device to allow stirring of the fermented product in the acetic acid assimilating fermenter 19. The acetic acid assimilating fermenter 19 may also be configured to allow external addition of microorganisms, such as symbiotic acetogenic bacteria.

[0094] The fermented products (such as acetic acid) and gas components (such as hydrogen and carbon dioxide) produced in the acetic acid assimilating fermenter 19 are transported to the dry methane fermenter 100 and discharged into the accommodation space 111 by the fluid discharge nozzle 160A.

[0095] The dry methane fermentation tank 100 contains the primary fermentation product of the crushed organic resource obtained in the acid-producing fermentation tank 15, the methane-containing fermentation product obtained in the hydrogen-assimilating fermentation tank 17, and the acetic acid-containing fermentation product obtained in the acetic acid-assimilating fermentation tank 19, and performs dry methane fermentation.

[0096] Specifically, the dry methane fermentation tank 100 is configured so that the primary fermentation product of the pulverized organic resource obtained in the acid-producing fermentation tank 15 is fed into the accommodation space 111 of the fermentation tank main body 110 of the dry methane fermentation tank 100 through the inlet 130, the fermentation product containing acetic acid obtained in the acetic acid utilization fermentation tank 19 is released into the accommodation space 111 by the fluid discharge nozzle 160A, and the fermentation product containing methane obtained in the hydrogen utilization fermentation tank 17 is released into the accommodation space 111 by the fluid discharge nozzle 160B.

[0097] In this embodiment, the fermented product stored in the dry methane fermenter 100 contains relatively large amounts of hydrogen, carbon dioxide, and acetic acid. Therefore, the dry methane fermenter 100 contains microorganisms derived from the acidogenic fermenter 15, the acetate-utilizing fermenter 19, and the hydrogen-utilizing fermenter 17. Among these, methanogenic archaea are primarily activated, particularly hydrogen-utilizing methanogens and acetate-utilizing methanogens. Hydrogen and carbon dioxide are then converted to methane primarily by the catabolic reaction (5) shown in FIG. 1. The fermented product, which contains a large amount of acetic acid, is converted to methane primarily by the catabolic reaction (4) shown in FIG. 1. The other catabolic reactions (1) to (3) shown in FIG. 1 occur in parallel with the catabolic reactions (4) and (5) as appropriate, depending on the amount of substrate present. The methane-containing gas produced in the dry methane fermenter 100 is transferred as biogas to the gas storage tank 23 via the desulfurization device 21. Furthermore, a part of the fermentation residue after fermentation is transported to the bacteria return tank 25, and the remainder is used as organic compost 310. The other configurations are as described above, and therefore will not be described again.

[0098] The desulfurization device 21 is a device for removing sulfur oxides (SOx) from the biogas. The desulfurization device 21 may be any device that can remove sulfur compounds, and desulfurization devices that employ various methods, such as wet methods using lime-gypsum methods, magnesium hydroxide methods, soda methods, etc., activated carbon adsorption methods, electron beam methods, lime ash methods, dry methods such as furnace desulfurization methods, and semi-dry methods such as spray drying methods, can be appropriately used. The gas storage tank 23 is a pressure-resistant tank that stores the biogas desulfurized in the desulfurization device 21.

[0099] The return culture tank 27 is a tank for fermenting a part of the fermentation residue produced in the dry methane fermenter 100 to produce seed cultures for each fermenter including the acid-producing fermenter 15 .

[0100] The reconstituting tank 27 is configured to be able to be sealed during fermentation, thereby ensuring an anaerobic environment during fermentation. Furthermore, the reconstituting tank 27 is equipped with a pressure gauge, a thermometer, and a temperature control device, and is configured to be able to control the temperature according to the fermentation status. Furthermore, the reconstituting tank 27 may be equipped with an appropriate stirring device so that the fermented product in the reconstituting tank 27 can be stirred. Furthermore, the reconstituting tank 27 may be configured so that a desired group of microorganisms can be added from outside.

[0101] <4. Dry methane fermentation method> Next, a dry methane fermentation method according to a preferred embodiment of the present invention will be described together with a method of using the above-described dry methane fermentation system 1.

[0102] The dry methane fermentation method of the present invention includes a step of performing dry methane fermentation of organic resources and / or raw materials derived from said organic resources using the dry methane fermenter of the present invention. Note that, in this embodiment, an example using the above-mentioned dry methane fermentation system 1 will be described, but it goes without saying that the dry methane fermentation method of the present invention can also use dry methane fermentation systems other than the dry methane fermentation system 1.

[0103] (4.1.) Crushing process In this step, the organic resource 300 is crushed into pieces of an appropriate size using a crusher 11. The size of the crushed pieces is not particularly limited as long as it is compatible with the kneading and explosion crusher 100 used in the next step, but can be, for example, 50 mm or less. Note that if the organic resource 300 already has an appropriate size, this step is omitted.

[0104] (4.2.) Kneading and Explosion Process Next, the crushed organic resource 300 is kneaded and exploded by the kneading and explosion crusher 200. Specifically, the crushed organic resource 300 is fed into the space 213 from the hopper 215 of the casing 210 while the Archimedes screw 220 is rotated.

[0105] As a result, the organic resource 300 is conveyed by the archimedes screw 220 toward the discharge port 230, while being kneaded and crushed by the relative motion between the side blades 240 and the screw blades 225 of the archimedes screw 220. Furthermore, as the organic resource 300 is conveyed by the archimedes screw 220, the pitch gradually decreases, causing it to be compressed and heated. This heating also promotes the above-mentioned crushing and heating.

[0106] Then, near the outlet 230, the pressure is suddenly released, causing the organic resource 300 to expand, burst, and be exploded and released from the kneading and explosion crusher 200. Through the above-mentioned action, the organic resource 300 is pulverized into pulverized organic resource material.

[0107] Furthermore, since the organic resource 300 is heated, some of the moisture is released from the organic resource 300 and becomes steam or a liquid separated from the solid matter of the organic resource 300. This makes it easier to adjust the moisture content in the kneader 13 in the subsequent stage.

[0108] Furthermore, the organic resource 300 typically contains moisture. When pressurized and heated in the presence of moisture, some components of the organic resource 300 decompose and / or denature. For example, starch and protein are denatured by heating, making them susceptible to the action of enzymes released by the microorganisms during fermentation. Furthermore, the solubilized matter in the organic resource 300 will dissolve in the heated water even if it has not been decomposed.

[0109] As described above, when the kneading and explosion treatment is carried out by the kneading and explosion crusher 200, the organic resource 300 is pulverized and defibrated by crushing, grinding, and explosion, and at the same time, the organic resource 300 is kneaded. At the same time, the components in the organic resource 300 are denatured and decomposed. In this way, when the kneading and explosion treatment is carried out by the kneading and explosion crusher 200, the organic resource 300 is simultaneously subjected to physical and chemical effects, and is brought into a state in which it is easy to ferment.

[0110] Furthermore, among the components of the organic resource 300, components with relatively small molecular weights are dissolved in the moisture and steam released from the organic resource 300. In other words, when the kneading and explosion treatment is performed by the kneading and explosion crusher 200, component separation is also carried out at the same time. Furthermore, the release of moisture from the organic resource 300 makes it possible to dehydrate and dry the resulting pulverized organic resource, facilitating moisture adjustment in the subsequent primary fermentation and dry methane fermentation.

[0111] It is preferable to carry out the kneading and explosion so that the moisture content of the organic resource 300 is, for example, 60% by mass to 80% by mass, and preferably 70% by mass to 75% by mass. Here, in this embodiment, the moisture content refers to the ratio of the mass of water to the mass of the entire composition.

[0112] The moisture content of the organic resource 300 can be adjusted, for example, by adjusting the kneading and explosion time by the kneading and explosion crusher 200. This is because the longer the kneading and explosion time, the more moisture is removed from the organic resource 300, and the more drying progresses. For example, when the moisture content of the organic resource 300 is 90% by mass or more, it is preferable to perform kneading and explosion for 30 minutes or more. On the other hand, when the moisture content of the organic resource 300 is less than 90% by mass, it is preferable to perform kneading and explosion for less than 30 minutes.

[0113] In addition, in order to ensure an anaerobic atmosphere in each fermentation process described below, it is preferable to cool the temperature of the pulverized organic resource material as quickly as possible after kneading and explosion, for example within one hour, to 70°C or less, particularly 55°C to 65°C.

[0114] After kneading and explosion, the resulting pulverized organic material is subjected to a kneading process and the subsequent acidogenic fermentation process. The liquid and gas separated from the pulverized organic material are then subjected to an acetic acid assimilative fermentation process.

[0115] In this embodiment, the case where the kneading and explosion machine 200 shown in Figures 4 to 6 is used as the kneading and explosion machine has been described. However, it goes without saying that other kneading and explosion machines, pulverizers, etc. can be used in place of the kneading and explosion machine 200 in the present invention.

[0116] (4.3.) Mixing process In this process, the pulverized organic resource material and the seed culture are mixed by kneading them together. Specifically, the pulverized organic resource material and the seed culture are placed in a kneader 13 and kneaded. The kneading time is not particularly limited and can be, for example, from 10 minutes to 180 minutes, preferably from 30 minutes to 60 minutes. In addition, in this process, the ratio of the pulverized organic resource material to the seed culture can be, for example, within a range of 5:5 to 9:1, preferably 6:4 to 8:2, by mass.

[0117] The seed culture can be a revertant culture obtained after methane fermentation. Alternatively, a separate seed culture can be prepared and mixed. The seed culture can be obtained, for example, by mixing polyphenols produced by the metabolism of microorganisms, trace elements such as minerals, and any organic matter, and then subjecting the mixture to anaerobic fermentation.

[0118] The resulting inoculum may include microbial communities such as hydrolytic bacteria, acidogenic bacteria, symbiotic acetogenic bacteria (e.g., thermophilic acetate-oxidizing bacteria belonging to the order Thermotogales, and decomposing bacteria of the order Clostridiales that degrade proteins and carbohydrates), and methanogenic archaea (hydrogen-utilizing methanogens such as Methanoculleus thermopyilus, Methanobacteriaceae, and Methanothermaceae, as well as acetate-utilizing methanogens such as Metyanosarcina thermophia). Research has shown that in methane fermentation, approximately 80% of methane production is due to acetate-oxidizing bacteria and hydrogen-utilizing methanogens, while approximately 20% is due to acetate-utilizing methanogens. In methane fermentation, methane is produced through highly efficient acetic acid decomposition by the combined action of acetate-oxidizing bacteria and hydrogen-utilizing methanogens.

[0119] The moisture content of the pulverized organic resource material after mixing with the seed culture in this step is not particularly limited, but can be, for example, 50% to 80% by mass, preferably 55% to 70% by mass. When the moisture content of the pulverized organic resource material is within this range, dry methane fermentation can be carried out effectively in the dry methane fermentation step described below.

[0120] (4.4.) Acidogenic Fermentation Process Next, the mixed pulverized organic resource material is subjected to primary fermentation to obtain a primary fermentation product of the pulverized organic resource material and a gas containing hydrogen and carbon dioxide. In this embodiment, the primary fermentation is carried out in an anaerobic atmosphere in an acid-producing fermenter 15.

[0121] In this embodiment, the pulverized organic material undergoes primary fermentation in the acid-producing fermenter 15, where it is decomposed into volatile fatty acids (VFAs) such as propionic acid, butyric acid, and isobutyric acid. Specifically, of the catabolic reactions shown in FIG. 1, catabolic reactions (1) and (2) primarily occur in the acid-producing fermenter 15, where the organic material, which is a high-molecular-weight organic material, is converted into low-molecular-weight organic material and then into volatile fatty acids. In this process, the hydrolytic bacteria and acid-producing bacteria are primarily activated. Furthermore, because the catabolic reactions shown in FIG. 1 occur in parallel, some of the catabolic reactions (3) to (5) naturally also occur in this process. Furthermore, in this process, hydrogen and carbon dioxide are produced as the high-molecular-weight organic material is decomposed into volatile fatty acids by primary fermentation.

[0122] The fermentation temperature in the primary fermentation is not particularly limited and is, for example, from 28° C. to 60° C., preferably from 30° C. to 55° C. This allows the hydrolytic bacteria and acidogenic bacteria to be sufficiently activated, allowing the desired catabolic reaction to proceed sufficiently.

[0123] The hydraulic retention time (HRT) in the primary fermentation is not particularly limited, but is, for example, 30 hours or more and 120 hours or less, preferably 60 hours or more and 80 hours or less.

[0124] The moisture content of the pulverized organic resource material during primary fermentation in this step is not particularly limited, but can be, for example, 50% to 80% by mass, preferably 55% to 70% by mass. When the moisture content of the pulverized organic resource material is within this range, primary fermentation proceeds efficiently and dry methane fermentation can be carried out effectively in the dry methane fermentation step described below.

[0125] Furthermore, the generated gas components (hydrogen and carbon dioxide) may be subjected to the hydrogen-assimilating methanogenic fermentation step described below even during primary fermentation. For example, a pressure reducing valve may be provided in the acid-producing fermenter 15 that opens when the pressure exceeds a predetermined level, so that when a certain amount of gas accumulates, it is transferred to the hydrogen-assimilating fermenter 17. This prevents a decrease in the reaction rates of the catabolic reactions (1) and (2) due to excessive hydrogen accumulation.

[0126] After primary fermentation in this process, if the pressure exceeds a predetermined level, some of the gaseous components (hydrogen, carbon dioxide, steam, etc.) are supplied to the hydrogen-utilizing methane production process via a pressure reducing valve. The primary fermentation product (a mixture of liquid and solid components) and the remainder of the gaseous components (hydrogen, carbon dioxide, steam, etc.) produced in this process are supplied to the dry methane fermentation process.

[0127] (4.5.) Hydrogen-utilizing methanogenic fermentation process In this step, the gas components (hydrogen, carbon dioxide, steam, etc.) generated in the acidogenic fermentation step are fermented by hydrogen-assimilating bacteria. In this embodiment, this step can be carried out in an anaerobic atmosphere in a hydrogen-assimilating fermenter 17.

[0128] In this embodiment, the hydrogen-assimilating bacteria produce methane using hydrogen and carbon dioxide as substrates in the hydrogen-assimilating fermenter 17. The microorganisms that may be present in the hydrogen-assimilating fermenter 17 may also be those that were present in the acid-producing fermenter 15, but the hydrogen-assimilating bacteria are particularly activated. The stored gas components (hydrogen, carbon dioxide, steam, etc.) are then converted to methane by the catabolic reaction (4) shown in FIG. 1.

[0129] The fermentation temperature in this step is not particularly limited and is, for example, from 40° C. to 70° C., preferably from 50° C. to 60° C. This allows the hydrogen-assimilating bacteria to be sufficiently activated, and the desired catabolic reaction to proceed sufficiently.

[0130] The hydraulic retention time (HRT) in this step is not particularly limited, but is, for example, 30 hours or more and 300 hours or less, preferably 50 hours or more and 200 hours or less.

[0131] In this step, the pH of the liquid component present is not particularly limited, but is, for example, 5.0 to 8.0, preferably 5.5 to 7.5. In addition, in this step, the pressure inside the hydrogen-assimilating fermenter 17 is not particularly limited, but is, for example, 0.10 MPa to 0.90 MPa, preferably 0.15 MPa to 0.25 MPa.

[0132] Furthermore, it is preferable to use a porous medium as the medium in this step. This ensures a medium for the hydrogen-utilizing bacteria and provides a sufficient reaction field for the methane production reaction by the hydrogen-utilizing methanogens. In particular, since the substrate in this step is a gas, the contact interface between the hydrogen-utilizing bacteria and the substrate is generally limited. However, the porosity of the porous inorganic medium provides a sufficient contact interface between the hydrogen-utilizing bacteria and the substrate, and fermentation is sufficiently promoted. Preferred porous media are as described above.

[0133] (4.6.) Acetic acid utilization fermentation process In this step, the gas and liquid released in the kneading and explosion machine 200 are contained, and a fermentation product containing acetic acid is produced by the symbiotic acetogenic bacteria. In this embodiment, this step can be carried out in an acetic acid assimilating fermenter 19 under an anaerobic atmosphere.

[0134] As mentioned above, the gas and liquid produced in the kneading and explosion process contain low-molecular-weight compounds such as relatively low-molecular-weight sugars (monosaccharides, oligosaccharides, etc.), low-molecular-weight peptides, and amino acids. Therefore, in this process, the catabolic reactions (2) and (3) shown in Figure 1 mainly proceed to decompose these compounds. In this process, acid-producing bacteria and symbiotic acetogenic bacteria are particularly activated.

[0135] The fermentation temperature in this step is not particularly limited and is, for example, from 20° C. to 40° C., preferably from 25° C. to 35° C. This allows the acidogenic bacteria and symbiotic acetogenic bacteria to be sufficiently activated, allowing the desired catabolic reactions to proceed sufficiently.

[0136] The hydraulic retention time (HRT) in this step is not particularly limited, but is, for example, 24 to 168 hours, preferably 72 to 120 hours. By adjusting the pH of the liquid component within the above range, activation of the symbiotic acetogenic bacteria can be further promoted.

[0137] In this step, the pH of the liquid component present is not particularly limited, but is, for example, 3.5 or more and 7.0 or less, preferably 4.0 or more and 6.5 or less.

[0138] After this step, the fermentation products (for example, acetic acid, etc.) and gas components (methane, steam, etc.) that are produced are subjected to a dry methane fermentation step.

[0139] (4.7.) Dry methane fermentation process In this step, the fermented products produced in the acidogenic fermentation step, the hydrogen-assimilating methanogenic fermentation step, and the acetate-assimilating fermentation step are further subjected to dry methane fermentation to obtain biogas containing methane.

[0140] Here, the hydrogen-assimilating methanogenic fermentation step is carried out after the acidogenic fermentation step, and the acetic acid-assimilating fermentation step is carried out in parallel with the hydrogen-assimilating methanogenic fermentation step and the acidogenic fermentation step. Therefore, fermented products from each step derived from the same organic resource 300 are usually not obtained at the same time. For this reason, dry methane fermentation may be carried out using fermented products from each step derived from different lots of organic resource 300.

[0141] In this embodiment, dry methane fermentation is carried out in a dry methane fermenter 100. Specifically, the primary fermentation product of the pulverized organic resource obtained in the acidogenic fermentation step is introduced into the accommodation space 111 of the fermenter body 110 of the dry methane fermenter 100 through the inlet 130, the fermentation product containing acetic acid obtained in the acetic acid assimilative fermentation step is released into the accommodation space 111 by the fluid discharge nozzle 160A, and the fermentation product containing methane obtained in the hydrogen assimilative fermentation step is released into the accommodation space 111 by the fluid discharge nozzle 160B.

[0142] The primary fermentation product introduced into the accommodation space 111 of the dry methane fermenter 100 is then carried by the conveyor belt 121 of the conveyor device 120. Thereafter, the primary fermentation product is transported toward the discharge port 145 side of the accommodation space 111 while being carried and transported by this conveyor belt 121. Then, the primary fermentation product undergoes dry methane fermentation while being carried and transported by this conveyor belt 121.

[0143] On the other hand, the fermented product containing acetic acid obtained in the acetic acid assimilative fermentation step and discharged from fluid discharge nozzle 160A, and the fermented product containing methane obtained in the hydrogen assimilative fermentation step and discharged from fluid discharge nozzle 160B, stir the fermented product including the primary fermented product, and are then subjected to dry methane fermentation. That is, the fermented products from these steps not only become the fermented product in this step, but also contribute to stirring the other fermented products including the primary fermented product.

[0144] In this embodiment, this step is usually carried out under an anaerobic atmosphere. The fermented products resulting from each step of dry methane fermentation contain large amounts of acetic acid and volatile fatty acids. Therefore, in this step, the catabolic reactions (3) to (5) shown in Figure 1 mainly proceed. Therefore, in this step, the symbiotic acetogenic bacteria and methanogenic archaea (especially acetate-utilizing methanogenic fermentation bacteria and hydrogen-utilizing methanogens) are particularly activated.

[0145] The fermentation temperature in this step is not particularly limited, and is, for example, 20°C or higher and 70°C or lower, preferably 25°C or higher and 60°C or lower.

[0146] In particular, it is preferable to set the fermentation temperature to 50°C or higher and 65°C or lower. In methane fermentation tanks that use methane fermentation, the fermentation state may become unstable due to the accumulation of organic acids. An example of an organic acid that is likely to accumulate is propionic acid. However, under the above temperature environment, propionate-oxidizing bacteria and hydrogen-utilizing methanogenic archaea can grow sufficiently at the same time, reducing the accumulation of propionic acid and activating acetate-utilizing methanogens.

[0147] The hydraulic retention time (HRT) in this step is not particularly limited, but is, for example, 168 hours to 720 hours, preferably 240 hours to 480 hours, and more preferably 288 hours to 432 hours. By setting the HRT in this range, the amount of methane obtained is maximized.

[0148] The moisture content of the fermented material in this step is not particularly limited, but can be, for example, 50% to 80% by mass, preferably 55% to 70% by mass. When the moisture content of the fermented material is within this range, dry methane fermentation can be carried out effectively.

[0149] In this manner, biogas is obtained. The obtained biogas is desulfurized by the desulfurization device 21 and stored in the gas storage tank 23.

[0150] Furthermore, a portion of the fermentation residue after dry methane fermentation is fermented in the reverting bacteria tank 25 and used as reverting bacteria, and the remainder can be used as organic compost 310, for example.

[0151] (3.7.) Reversion culture generation process In this step, the fermentation residue produced in the dry methane fermentation step is fermented in an anaerobic atmosphere to obtain return bacteria (seed bacteria).

[0152] The fermentation temperature in this step is not particularly limited, and is, for example, 20°C or higher and 50°C or lower, preferably 25°C or higher and 45°C or lower. The hydraulic retention time (HRT) in this step is not particularly limited, but is, for example, 24 hours or more and 120 hours or less, preferably 48 hours or more and 96 hours or less. In this step, the pH of the liquid component present is not particularly limited, but is, for example, 6.0 or more and 9.0 or less, preferably 7.0 or more and 8.0 or less.

[0153] <5. Effects> Next, the effects achieved by the dry methane fermentation tank 100, the dry methane fermentation system 1, and the dry methane fermentation method according to this embodiment will be described.

[0154] (5.1. Dry methane fermenter) In the above-described dry methane fermentation tank 100, the organic resource 300 introduced through the introduction port 130 is carried by the conveyor belt 121 of the conveyor device 120. The organic resource 300 carried by the conveyor belt 121 is then transported toward the discharge port 145 in the fermentation tank main body 110 of the dry methane fermentation tank 100 and undergoes dry methane fermentation. When the organic resource 300, which has become a fermentation residue after dry methane fermentation, reaches the end of the conveyor device 120 on the discharge port 145 side, it is transferred from the conveyor belt 121 to the discharge space 143 of the discharge section 140. The organic resource 300 is then discharged from the discharge port 145 to the outside of the dry methane fermentation tank 100. Meanwhile, biogas generated in the dry methane fermentation is transported to the outside of the dry methane fermentation tank 100 via the biogas recovery nozzle 150.

[0155] Therefore, according to this embodiment, it is possible to provide a dry methane fermenter 100 that has a simple configuration, is easy to maintain, and is capable of sufficiently fermenting the material to be fermented.

[0156] That is, first, in the dry methane fermentation tank 100 according to this embodiment, even though it does not have a mechanical stirring device and is a continuous methane fermentation tank, it is possible to transfer the organic resource 300 and perform sufficient dry methane fermentation.

[0157] Generally, when organic resources are forcibly stirred using a mechanical stirrer in dry methane fermentation, the high solids concentration of the organic resources makes them relatively difficult to move, requiring a large amount of energy for stirring. In this case, a large load is likely to be placed on the stirrer, and frequent maintenance is required to maintain the functionality of the stirrer. On the other hand, omitting the stirrer makes it difficult to transport the organic resources required in a continuous methane fermenter. In contrast, the dry methane fermenter 100 according to this embodiment solves these problems without using a mechanical stirrer.

[0158] Furthermore, by transporting the organic resources 300 within the fermenter main body 110 using the conveyor device 120, organic resources 300 added at the same time are prevented from mixing with organic resources 300 added earlier or later, making it easier to manage the fermentation time of each organic resource 300. In other words, there is no risk of some of the organic resources 300 unintentionally moving excessively in the flow direction due to agitation, resulting in them being discharged from the dry methane fermenter 100 without undergoing sufficient fermentation. This allows more organic resources 300 to be used more effectively in generating biogas.

[0159] Furthermore, in this embodiment, the heating device 170 is disposed inside the fermenter main body 110. This allows the heat emitted from the heating device 170 to be efficiently transferred to the organic resource 300, making the dry methane fermentation in the dry methane fermenter 100 highly energy efficient.

[0160] (5.2. Dry Methane Fermentation System and Dry Methane Fermentation Method) (5.2.1.) First, in this embodiment, dry methane fermentation is performed using the dry methane fermenter 100 according to the embodiment described above. Therefore, the dry methane fermentation production system 1 and the dry methane fermentation method according to the embodiment can achieve the effects of the dry methane fermenter 100 described above.

[0161] Furthermore, in the dry methane fermentation system 1 and the dry methane fermentation method according to this embodiment, the fermentation efficiency is improved and the biogas yield is improved for the following reasons (5.2.2.) to (5.2.5.). Therefore, even if the dimensions of the dry methane fermenter 100 are relatively small or the dry methane fermentation time is shortened, sufficient dry methane fermentation is possible. Furthermore, sufficient fermentation efficiency can be maintained even if the agitation in the dry methane fermenter 100 is gentle.

[0162] (5.2.2.) In this embodiment, prior to the dry methane fermentation of the pulverized organic resource material, the pulverized organic resource material is subjected to primary fermentation in an acid-producing fermenter 15 to obtain a primary fermented product of the pulverized organic resource material and a gas containing hydrogen and carbon dioxide (acid-producing fermentation step).Then, the primary fermented product of the pulverized organic resource material is subjected to dry methane fermentation in a dry methane fermenter 100 (dry methane fermentation step).

[0163] When the acidogenic fermentation process and the dry methane fermentation process are combined, the primary fermentation in the acidogenic fermentation process mainly involves the above-mentioned catabolic reactions (1) and (2), while the dry methane fermentation in the dry methane fermentation process mainly involves the catabolic reactions (3) to (5).

[0164] In each of the catabolic reactions (1) to (3) shown in Figure 1, hydrogen is generated as the substrate is broken down into smaller molecules. When these catabolic reactions (1) to (3) occur in parallel, the hydrogen generated by catabolic reactions (1) and (2), which convert high molecular weight organic matter into low molecular weight organic matter and produce volatile fatty acids, slows the rate of catabolic reaction (3), which produces acetic acid from volatile fatty acids. Similarly, the hydrogen generated by catabolic reaction (3) can also slow the rate of catabolic reactions (1) and (2).

[0165] Therefore, by combining the acidogenic fermentation process with the dry methane fermentation process, the hydrogen produced by the catabolic reactions (1) and (2), which convert high molecular weight organic matter into low molecular weight organic matter and then produce volatile fatty acids in the dry methane fermentation process, does not slow down the rate of the catabolic reaction (3), which converts volatile fatty acids into acetic acid, while the hydrogen produced by the catabolic reaction (3) in the acidogenic fermentation process does not slow down the rate of the catabolic reactions (1) and (2). As a result, the overall efficiency of the dry methane fermentation process is improved.

[0166] As described above, the catabolic reactions (3) to (5) mainly occur in the dry methane fermentation process carried out in the dry methane fermenter 100. Here, the catabolic reaction (3) of volatile fatty acids to acetic acid by the symbiotic acetogenic bacteria is expressed as follows, taking propionic acid as an example. CH3CH2COO - +3H2O → CH3COO - +HCO3 - +H + +3H2 (formula 1)

[0167] Here, the standard free energy ΔG of the reaction expressed by Eq. 0 is +76.1 kJ / mol. Therefore, the reaction represented by Equation 1 is an endothermic reaction that requires heat to be supplied from an external source. Also, the reaction rate of Equation 1 slows down as hydrogen (H2) accumulates.

[0168] On the other hand, the catabolic reaction (4) of hydrogen and carbon dioxide to methane by hydrogen-utilizing methanogens can be expressed as follows: 4H2+HCO3 - +H + →CH4+3H2O (Formula 2)

[0169] Here, the standard free energy ΔG of the reaction expressed by Eq. 0 is -135.6 kJ / mol. Therefore, the reaction represented by Equation 2 is an exothermic reaction that does not require an external heat supply. When the catabolic reactions (3) and (4) represented by Equations 1 and 2 are coupled, they are expressed as the following coupled reaction equation: 4CH3CH2COO - +3H2O → CH3COO - +HCO3 - +H + +3CH4 (formula 3)

[0170] Here, the standard free energy of the conjugation reaction, ΔG, is expressed as Eq. 0 is -102.4 kJ / mol. Therefore, the coupled reaction represented by formula 3 is an exothermic reaction that does not require the supply of heat from an external source. Therefore, when the catabolic reactions (3) and (4) represented by formulas 1 and 2 are coupled, the reaction proceeds naturally without the input of heat from an external source. Furthermore, when the catabolic reactions (3) and (4) represented by formulas 1 and 2 are coupled, the hydrogen produced in the catabolic reaction (3) is consumed in equal amounts in the catabolic reaction (4), so no hydrogen accumulates in the coupled reaction. For these reasons, in this embodiment, the dry methane fermentation performed after the primary fermentation in the acidogenic fermentation step has excellent fermentation efficiency.

[0171] (5.2.3.) Furthermore, in this embodiment, gaseous components (hydrogen, carbon dioxide, etc.) produced in the primary fermentation of the acidogenic fermentation step are fermented in the hydrogen-assimilating fermenter 17 to obtain a gas containing methane (hydrogen-assimilating methanogenic fermentation step). In this way, hydrogen, which may inhibit each of the catabolic reactions (1) to (3) in the acidogenic fermentation step and the dry methane fermentation step, is converted into methane in the hydrogen-assimilating methanogenic fermentation step, thereby improving the overall efficiency of the dry methane fermentation. In particular, in this embodiment, the use of a porous medium in the hydrogen-assimilating methanogenic fermentation step also improves the efficiency of the fermentation itself in the hydrogen-assimilating methanogenic fermentation step.

[0172] (5.2.4.) In particular, in this embodiment, the organic resource 300 is kneaded and exploded using a kneading and explosion crusher 200 equipped with an Archimedes screw 220. In this kneading and explosion crusher, the organic resource 300 is pulverized and defibrated by pulverization, grinding, and explosion, while the organic resource 300 is kneaded. At the same time, the components in the organic resource 300 are heated by the heat generated by compression and are denatured and decomposed. In this way, when the kneading and explosion treatment is performed using the kneading and explosion crusher 200, the organic resource 300 is simultaneously subjected to physical and chemical effects, and is brought into a state in which it is easy to ferment.

[0173] Furthermore, among the components of the organic resource 300, components with relatively small molecular weights are dissolved in the moisture and steam released from the organic resource 300. That is, when the kneading and explosion treatment is performed by the kneading and explosion-crushing machine 100, component separation is also performed at the same time.

[0174] In particular, during the kneading and explosion process using the kneading and explosion crusher 200, moisture is removed from the organic resource (pulverized organic resource) 300. In other words, the organic resource 300 can be dried. This makes it easier to adjust the moisture content during primary fermentation and dry methane fermentation.

[0175] In dry methane fermentation, the moisture content of the material to be fermented is lower than in wet methane fermentation, and for this reason, in the past, drying treatment was often required as a pretreatment. However, in this embodiment, the drying treatment can be essentially performed simultaneously with the above-mentioned kneading and explosion-crushing, and a separate drying treatment can be omitted. As a result, in this embodiment, the device configuration required for pretreatment of dry methane fermentation can be simplified.

[0176] (5.2.5.) In particular, in this embodiment, the gas and liquid generated during the kneading and explosion process are contained, and a fermentation product containing acetic acid is produced by acid-producing bacteria and symbiotic acetogenic bacteria. The gas and liquid generated during the kneading and explosion process contain many relatively low-molecular-weight substances derived from the organic resource 300. By separately fermenting these low-molecular-weight compartments in an acetic acid-utilizing fermenter 19 together with a microorganism group including symbiotic acetogenic bacteria, it is possible to efficiently produce acetic acid, hydrogen, and carbon dioxide, which serve as substrates for dry methane fermentation.

[0177] That is, as described above, when catabolic reactions (1) to (3) occur in parallel, the hydrogen produced by catabolic reactions (1) and (2), which convert high molecular weight organic matter into low molecular weight organic matter and produce volatile fatty acids, slows the rate of catabolic reaction (3), which produces acetic acid from volatile fatty acids. Similarly, the hydrogen produced by catabolic reaction (3) can also slow the rate of catabolic reactions (1) and (2). In this embodiment, the gas and liquid generated during the kneading and explosion process, which contain relatively low molecular weight components, are fermented primarily through catabolic reaction (3), which produces acetic acid from volatile fatty acids, separately from the fermentation of the pulverized organic resource, which is primarily through catabolic reactions (1) and (2). This prevents such a decrease in reaction rate, and as a result, improves the efficiency of dry methane fermentation.

[0178] The present invention has been described in detail above based on a preferred embodiment, but the present invention is not limited to this, and each component can be replaced with any component that can perform a similar function, or any component can be added.

[0179] For example, in the above-described embodiment, the conveyor device of the dry methane fermenter is described as including a conveyor belt, but the present invention is not limited thereto, and the conveyor device may be any conveyor device such as an apron conveyor, a chain conveyor, a trolley conveyor, a roller conveyor, etc. Alternatively, the conveyor device may be a combination of multiple conveyor devices.

[0180] For example, in the above-described embodiment, the heating device 170 of the dry methane fermentation tank is described as being attached to the upper inside of the fermentation tank body, but the present invention is not limited to this, and the heating device can be attached to any position of the fermentation tank body.

[0181] Furthermore, in the above-described embodiment, the dry methane fermentation tank has been described as being used in the above-described dry methane fermentation system 1, but the present invention is not limited to this, and the dry methane fermentation tank of the present invention can be used in any dry methane fermentation system or dry methane fermentation method.

[0182] For example, in the above-described embodiment, the pulverized organic resource is described as being subjected to primary fermentation in an acid-producing fermenter, but the present invention is not limited to this. The dry methane fermentation system of the present invention does not need to include an acid-producing fermenter. That is, the acid-producing fermentation step may be omitted. In this case, the pulverized organic resource is directly subjected to dry methane fermentation in the dry methane fermenter.

[0183] Furthermore, for example, in the above-described embodiment, the gas components generated in the acid-producing fermenter are described as being fermented in the hydrogen-assimilating fermenter 17, but the present invention is not limited to this. For example, the hydrogen-assimilating fermenter may be omitted. That is, the hydrogen-assimilating fermentation step may be omitted. In this case, for example, all of the gas components generated in the acid-producing fermenter are directly introduced into the dry methane fermenter.

[0184] Furthermore, for example, in the above-described embodiment, the methane-containing gas obtained by fermentation in the hydrogen-assimilating fermenter 17 is transferred to the dry methane fermenter 100, but the present invention is not limited to this. For example, the methane-containing gas obtained by fermentation in the hydrogen-assimilating fermenter 17 may pass directly through the desulfurization device 21 without being transferred to the dry methane fermenter 100, and may be stored directly in the gas storage tank 23 as biogas.

[0185] In the above-described embodiment, the organic resource is pulverized and dried using a kneading and explosion-crushing machine, but the present invention is not limited to this. The dry methane fermentation system and dry methane fermentation method of the present invention do not necessarily have to include the kneading and explosion-crushing machine described above. In this case, a known drying device and pulverizer are used.

[0186] In the above-described embodiment, the gas and liquid released from the kneading-explosion machine are fermented in an acetic acid assimilating fermenter. However, the present invention is not limited to this. For example, the dry methane fermentation system of the present invention does not need to include an acetic acid assimilating fermenter. That is, the acetic acid assimilating fermentation step may be omitted. In this case, the gas and liquid released from the kneading-explosion machine are subjected to primary fermentation together with the pulverized organic resource in the acid-producing fermenter. [Explanation of symbols]

[0187] 1. Dry methane fermentation system 11 Crusher 13 Kneader 15 Acid-producing fermenter 17 Hydrogen-utilizing fermenter 19 Acetic acid utilization fermenter 21 Desulfurization equipment 23 Gas storage tank 25 Reconstitution tank 100 Dry methane fermentation tank 110 Fermentation tank body 120 Conveyor equipment 121 Conveyor Belt 130 Inlet 140 Discharge section 145 Outlet 150 Biogas recovery nozzle 160A, 160B Fluid Discharge Nozzle 170 Heating device 200 Kneading and Explosion Machine 210 cabinet 215 Hopper 220 Archimedes Screw 230 Outlet 240 Side blade 250 Outlet side blade 260 Water pipe 270 Power Source

Claims

1. a fermenter body for storing organic resources and / or organic resource-derived raw materials in a storage space and performing dry methane fermentation; an inlet provided in the fermenter body for introducing the organic resource and / or the organic resource-derived raw material into the fermenter body; a discharge port provided in the fermenter body for discharging a fermentation residue of the organic resource and / or the organic resource-derived raw material from the fermenter body; a conveyor device that carries the organic resource and / or the organic resource-derived raw material introduced through the introduction port and transports the organic resource toward the discharge port.

2. The dry methane fermenter of claim 1 , wherein the conveyor device includes a belt conveyor.

3. 2. The dry methane fermenter according to claim 1, further comprising a fluid discharge nozzle attached to the fermenter body for discharging a fluid toward the accommodation space.

4. The dry methane fermenter according to claim 3 , wherein the fluid discharge nozzle discharges a fluid toward the organic resource and / or the organic resource-derived raw material carried by the conveyor device.

5. 2. The dry methane fermenter according to claim 1, further comprising a temperature control device disposed on the accommodation space side of the fermenter body to control the temperature within the accommodation space.

6. A dry methane fermentation system comprising the dry methane fermenter according to any one of claims 1 to 5.

7. The system further includes an acid-producing fermenter that ferments an organic resource in the presence of an acid-producing bacterium to produce a primary fermentation product of the organic resource and a gas containing hydrogen and carbon dioxide, The dry methane fermentation system according to claim 6 , wherein the dry methane fermentation tank is a fermentation tank that accommodates the primary fermented product and performs dry methane fermentation.

8. The dry methane fermentation system according to claim 7, further comprising a hydrogen-utilizing fermenter that accommodates the gas produced in the acid-producing fermenter and ferments the gas with hydrogen-utilizing methanogens.

9. The dry methane fermentation system according to claim 8 , wherein the hydrogen-utilizing fermenter contains a porous inorganic medium.

10. Further, a kneading and explosion machine is provided for kneading and exploding the organic resources to produce pulverized organic resources, The kneading and explosion crusher has a housing having a cylindrical space and an Archimedes screw arranged in the space, The housing has an inlet for introducing the organic resource at one cylindrical end side of the space, and an outlet for removing the pulverized organic resource at the other cylindrical end side of the space, 7. The dry methane fermentation system according to claim 6, wherein the pitch of the Archimedes screw gradually decreases from the inlet to the outlet.

11. Further, an acetic acid assimilating fermenter is provided in which acetic acid assimilating methanogens are used to produce a fermentation product containing acetic acid from the gas and liquid generated from the organic resource in the kneading and explosion machine, The dry methane fermentation system according to claim 10 , wherein the fermented product containing acetic acid is subjected to dry methane fermentation in the dry methane fermenter.

12. A dry methane fermentation method comprising a step of performing dry methane fermentation of an organic resource and / or a raw material derived from the organic resource using the dry methane fermenter according to any one of claims 1 to 5.

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