Biomass treatment device

Abstract

To provide a biomass treatment device that facilitates enhancement of methane concentration in biogas, which in turn enables utilization of the biogas for diverse purposes.SOLUTION: A biomass treatment device 1A configured to produce a biogas BG through fermentation of biomass, the device including: a storage tank 2 that stores a fermentation liquid FL in which the biomass is fermented; and a fine bubble supply part 3 that supplies a hydrogen-containing gas to the fermentation liquid FL in the form of fine bubbles. It is preferable to provide a gas supply part 4 that supplies a carbon dioxide-containing gas to the fermentation liquid FL.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a biomass treatment apparatus for producing biogas by fermenting biomass. [Background technology]

[0002] The use of biogas has been attracting attention from the viewpoints of preventing environmental pollution and regenerating energy.

[0003] Anaerobic fermentation of organic resources (biomass) derived from living organisms ultimately produces combustible biogas, primarily composed of methane and carbon dioxide. Anaerobic fermentation of biomass can be broadly divided into two biochemical reactions: a solubilization process using hydrolytic and acidogenic bacteria, and a methane fermentation process using methanogenic bacteria. High molecular weight organic compounds such as proteins, carbohydrates, and fats are broken down into lower molecular weight compounds by hydrolytic bacteria, resulting in higher fatty acids, amino acids, and sugars. The lower molecular weight organic compounds are then broken down by acidogenic bacteria into hydrogen, carbon dioxide, and organic acids (acetic acid, butyric acid, propionic acid, pyruvic acid, formic acid, lactic acid, succinic acid, etc.). The organic acids are then subjected to methane fermentation by methanogenic bacteria, producing methane.

[0004] As a biomass treatment device that produces biogas containing methane and the like by anaerobic fermentation as described above, a device equipped with a single-tank fermenter that performs a solubilization step and a methane fermentation step is known (see, for example, Patent Document 1). Also known is a device equipped with a two-tank fermenter in which an acid fermenter is provided in the first stage to perform the solubilization step, and a methane fermenter is provided in the second stage to perform the methane fermentation step (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-183481 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-289946 Summary of the Invention [Problem to be solved by the invention]

[0006] In the biomass treatment devices disclosed in Patent Documents 1 and 2, carbon dioxide is inevitably produced by the decomposition of low-molecular-weight organic matter by acid-producing bacteria, and the methane concentration in the generated biogas is low, at approximately 50 to 60%, which has the problem that the biogas can only be used for limited purposes.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a biomass treatment device that can increase the methane concentration in biogas, thereby enabling the biogas to be used for a variety of purposes. [Means for solving the problem]

[0008] The characteristic configuration of the biomass processing device according to the present invention for solving the above problems is as follows: A biomass treatment device that ferments biomass to produce biogas, A storage tank for storing a fermentation liquid obtained by fermenting the biomass; a fine bubble supply unit that supplies hydrogen-containing gas to the fermentation liquid as fine bubbles; The purpose is to provide the following.

[0009] In this biomass treatment device, the fine bubble supply unit supplies the hydrogen-containing gas to the fermentation liquid as fine bubbles, thereby increasing the rate at which the hydrogen-containing gas dissolves in the fermentation liquid. As a result, the hydrogen required for the CO2 reduction methane production reaction by hydrogen-utilizing methanogens, which use hydrogen and carbon dioxide as substrates, can be rapidly supplied, and carbon dioxide can be efficiently converted into methane. This increases the methane concentration in the biogas, enabling the biogas to be used for a variety of purposes.

[0010] In the biomass treatment device according to the present invention, It is preferable to provide a gas supply unit that supplies a carbon dioxide-containing gas to the fermentation liquid.

[0011] According to the biomass treatment device of this configuration, even after the carbon dioxide produced by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria is consumed in the CO2-reducing methane production reaction by the hydrogen-assimilating methanogens, methane is still produced by the CO2-reducing methane production reaction by the hydrogen-assimilating methanogens using as substrates the hydrogen derived from the hydrogen-containing gas supplied by the fine bubble supply unit and the carbon dioxide derived from the carbon dioxide-containing gas supplied by the gas supply unit. Therefore, the amount of methane produced can be increased.

[0012] In the biomass treatment device according to the present invention, The fine bubbles preferably further contain a carbon dioxide-containing gas.

[0013] According to the biomass treatment device of this configuration, in addition to the hydrogen-containing gas supplied by the fine bubble supply unit, carbon dioxide-containing gas is also supplied to the fermentation liquor as fine bubbles, thereby increasing the dissolution rate of the hydrogen-containing gas and carbon dioxide-containing gas into the fermentation liquor. As a result, even after the carbon dioxide produced by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria is consumed in the CO2-reducing methane production reaction by the hydrogen-assimilating methanogens, the hydrogen and carbon dioxide required for the CO2-reducing methane production reaction by the hydrogen-assimilating methanogens, which use hydrogen and carbon dioxide as substrates, can be quickly supplied. Therefore, the CO2-reducing methane production reaction by the hydrogen-assimilating methanogens continues to proceed efficiently, improving methane production efficiency.

[0014] In the biomass treatment device according to the present invention, It is preferable that a circulation circuit be provided for returning a portion of the biogas to the fine bubble supply unit and circulating it.

[0015] According to the biomass treatment device of this configuration, a portion of the biogas is returned to the fine bubble supply section and circulated, and methane is produced by a CO2 reduction methanogenesis reaction by hydrogen-utilizing methanogens using the hydrogen and carbon dioxide remaining in the biogas as substrates, thereby further increasing the methane concentration in the biogas.

[0016] In the biomass treatment device according to the present invention, It is preferable that a circulation circuit be provided for returning a portion of the biogas to the gas supply unit and circulating it.

[0017] According to the biomass treatment device of this configuration, a portion of the biogas is returned to the gas supply section and circulated, and methane is produced by a CO2 reduction methanogenesis reaction mediated by hydrogen-utilizing methanogens using the hydrogen and carbon dioxide remaining in the biogas as substrates, thereby further increasing the methane concentration in the biogas.

[0018] In the biomass treatment device according to the present invention, The storage tank is preferably configured so that the inside thereof can be pressurized.

[0019] According to the biomass treatment device of this configuration, the inside of the storage tank is pressurized, which makes it possible to prevent hydrogen and carbon dioxide that have once dissolved in the fermentation liquid from being released from the fermentation liquid, and also to further improve the dissolution rate of the hydrogen-containing gas into the fermentation liquid. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a biomass treatment apparatus according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a schematic configuration of a biomass treatment apparatus according to the second embodiment. [Figure 3] FIG. 3 is a schematic diagram showing a schematic configuration of a biomass treatment apparatus according to the third embodiment. [Figure 4]FIG. 4 is a schematic diagram showing a schematic configuration of a biomass treatment apparatus according to the fourth embodiment. [Figure 5] FIG. 5 is a schematic diagram showing a schematic configuration of a biomass treatment apparatus according to the fifth embodiment. [Figure 6] FIG. 6 is a schematic diagram showing a schematic configuration of a biomass treatment apparatus according to the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described below with reference to the drawings. In this specification, biomass refers to organic resources derived from living organisms. Examples of biomass include organic waste, resource crops, and their waste. Examples of organic waste include food waste, manure, sludge, food processing residues, livestock waste, waste oil, animal fats and oils, agricultural crop residues, and organic wastewater from the food industry, paper industry, or livestock industry. Examples of sludge include sewage treatment sludge, human waste treatment sludge, septic tank sludge, and treated industrial wastewater from food factories. Examples of resource crops include potatoes, sugar beets, rapeseed, sunflowers, wheat, chlorella, water hyacinth, corn, sugarcane, and waste generated during the processing of these crops. In this specification, biogas refers to gas generated by anaerobic fermentation of biomass. Examples of biogas components include hydrogen gas, methane gas, and carbon dioxide gas.

[0022] Biomass treatment devices to which the present invention can be applied include in-situ and ex-situ types. In the in-situ type, hydrogen is introduced into a methane fermentation tank, which performs methane fermentation following acid fermentation of biomass. In the first to sixth embodiments described below, in the in-situ type, the methane fermentation tank corresponds to the storage tank 2 described below, and in the storage tank 2, methane fermentation follows acid fermentation of biomass and hydrogen is introduced. In the ex-situ type, a bioreactor that only performs the biomethanation reaction is installed separately from the methane fermentation tank, and hydrogen is introduced into the bioreactor. In the first to sixth embodiments described below, in the ex-situ type, the bioreactor corresponds to the storage tank 2 described below, and hydrogen is introduced into the storage tank 2, where the biomethanation reaction of converting carbon dioxide to methane occurs. In the following embodiments, a biomass treatment device that can be applied to both in-situ and ex-situ types and that ferments organic waste to produce biogas will be described as an example. However, the present invention is not intended to be limited to the embodiments described below or the configurations shown in the drawings. "Biomethanation" refers to the production of methane through methane fermentation using hydrogen, carbon dioxide, and other nutrients necessary for the growth of microorganisms as raw materials.

[0023] First Embodiment <Overall structure> Fig. 1 is a schematic diagram showing the general configuration of a biomass processing device 1A according to a first embodiment. As shown in Fig. 1, the biomass processing device 1A includes a storage tank 2, a fine bubble supply unit 3, a gas supply unit 4, and a biogas recovery unit 5.

[0024] Here, when the biomass processing device 1A is an in-situ type, the storage tank 2 is used as a methane fermentation tank. When the biomass processing device 1A is used as a wet fermentation device, the storage tank 2 stores a fermentation liquid obtained by fermenting organic waste, and the solids concentration in the tank is adjusted to around 10% by weight or less, and the organic waste is fermented in a medium-temperature environment (30 to 45°C) or a high-temperature environment (45 to 65°C) to produce biogas. When the biomass processing device 1A is used as a dry fermentation device, the solids concentration in the storage tank 2 is adjusted to around 8 to 40% by weight, and the organic waste is fermented in a high-temperature environment (45 to 65°C) to produce biogas. Note that dry fermentation devices include horizontal dry fermentation devices and vertical dry fermentation devices.

[0025] When the biomass treatment device 1A is an ex-situ type, the storage tank 2 is used as a bioreactor that is solely responsible for the biomethanation reaction. Note that a fermented liquid obtained by fermenting organic waste in a wet or dry methane fermenter installed separately from the storage tank 2 may be introduced into the storage tank 2.

[0026] <Storage tank> The storage tank 2 has a cylindrical body 2a with an axis (not shown) oriented in the vertical direction, and is a tank with the upper and lower sides of the body 2a closed. The storage tank 2 is configured to store a fermentation liquid FL obtained by methane fermentation of biomass, and to fill the space above the liquid level of the fermentation liquid FL with biogas BG.

[0027] <Fine bubble supply unit> The fine bubble supply unit 3 supplies hydrogen-containing gas as fine bubbles to the fermentation liquid FL in the storage tank 2. The hydrogen-containing gas means a gas containing at least 10% hydrogen by volume relative to the total hydrogen-containing gas. The hydrogen gas content in the hydrogen-containing gas is preferably 80% or more, more preferably 90% or more, and most preferably 95% or more. There is no particular upper limit to the hydrogen gas content in the hydrogen-containing gas, and it may be 100%.

[0028] The fine bubble supply unit 3 includes an H2 gas supply source 11, a gas supply pipe 12, and a fine bubble generator 13, which are arranged in this order from the upstream side to the downstream side of the gas flow.

[0029] Although detailed description using drawings is omitted, the H2 gas supply source 11 is configured to include a hydrogen storage unit that stores hydrogen-containing gas under high pressure, a pressure reducing valve that reduces the pressure of the high-pressure hydrogen-containing gas from the hydrogen storage unit, etc. Examples of the hydrogen used here include hydrogen obtained by electrolyzing water using electricity generated by renewable energy sources such as solar, wind, and geothermal energy, and surplus hydrogen from petrochemical plants, etc. The upstream end of the gas supply pipe 12 is connected to the H2 gas supply source 11, and the downstream end of the gas flow is connected to a fine bubble generator 13 disposed in the fermentation liquid FL in the storage tank 2.

[0030] The fine bubble generator 13 emits hydrogen-containing gas supplied from the H2 gas supply source 11 via the gas supply pipe 12 as fine bubbles. Here, "fine bubbles" includes "microbubbles" and "ultrafine bubbles," with "microbubbles" being bubbles with a diameter of less than 100 μm but not less than 1 μm, and "ultrafine bubbles" being bubbles with a diameter of less than 1 μm. Examples of fine bubble generators that can be used include a swirling flow method in which bubbles are generated by mixing a gas (hydrogen-containing gas) with a liquid (fermentation liquid FL) and swirling the mixture at high speed; a pressure dissolution method in which bubbles are generated by applying pressure to a gas, dissolving it in a liquid, and then releasing the pressure all at once; and a micropore method in which bubbles are generated by applying pressure to a gas passing through a micropore such as an orifice.

[0031] <Gas supply section> The gas supply unit 4 supplies the carbon dioxide-containing gas as normal bubbles (bubbles with a diameter of 1 mm or more) to the fermentation liquid FL in the storage tank 2. The carbon dioxide-containing gas means a gas containing at least 10% carbon dioxide by volume relative to the total carbon dioxide-containing gas. The carbon dioxide content in the carbon dioxide-containing gas is preferably 40% or more, more preferably 90% or more, and most preferably 95% or more. There is no particular upper limit to the carbon dioxide content in the carbon dioxide-containing gas, and it may be 100%.

[0032] The gas supply unit 4 includes a CO2 gas supply source 21 and a gas inlet pipe 22. Although not shown in detail, the CO2 gas supply source 21 includes a carbon dioxide storage unit that stores carbon dioxide-containing gas under high pressure, a pressure reducing valve that reduces the pressure of the high-pressure carbon dioxide-containing gas from the carbon dioxide storage unit, and other components. Examples of the carbon dioxide-containing gas used here include gas containing carbon dioxide recovered from combustion exhaust gas generated during the combustion of waste materials, etc., by chemical absorption, membrane separation, physical absorption, solid absorption, or other methods, and biogas containing carbon dioxide generated during the fermentation of biomass. The upstream end of the gas inlet pipe 22 in the gas flow direction is connected to the CO2 gas supply source 21, and the downstream end of the gas flow direction is arranged so that hydrogen-containing gas can be injected into the fermentation liquid FL in the storage tank 2.

[0033] <Biogas Recovery Section> The biogas recovery section 5 is equipped with a gas discharge pipe 25. The upstream side of the gas flow of the gas discharge pipe 25 is connected to a gas vent port 26 provided on the top surface of the storage tank 2 so that the biogas BG can be discharged outside the tank. A gas holder 27 is connected to the downstream side of the gas flow of the gas discharge pipe 25. The biogas BG extracted from the storage tank 2 through the gas discharge pipe 25 is temporarily stored in the gas holder 27 and then effectively utilized. A gas purification device may be connected to the downstream side of the gas flow of the gas holder 27. Examples of gas purification devices include a device that removes hydrogen sulfide from the biogas BG, a moisture removal device, a device that further reduces CO2 from the biogas BG using pressure swing adsorption (PSA), membrane separation, high-pressure water absorption, chemical absorption, physical absorption, etc., and a siloxane removal device.

[0034] In the biomass processing apparatus 1A configured as described above, hydrogen-containing gas is supplied as fine bubbles from the fine bubble supply unit 3 into the fermentation liquid FL in the storage tank 2. Furthermore, carbon dioxide-containing gas is supplied from the gas supply unit 4 into the fermentation liquid FL in the storage tank 2. The biogas BG produced by methane fermentation accumulates above the liquid surface of the fermentation liquid FL stored in the storage tank 2, and is recovered by the biogas recovery unit 5 for effective use.

[0035] In the biomass processing apparatus 1A, the fine bubble supply unit 3 supplies the hydrogen-containing gas to the fermentation liquid FL as fine bubbles, thereby increasing the rate at which the hydrogen-containing gas dissolves in the fermentation liquid FL. As a result, the hydrogen required for the CO2 reduction methane production reaction by hydrogen-utilizing methanogens, which use hydrogen and carbon dioxide as substrates, can be quickly supplied, allowing carbon dioxide to be efficiently converted into methane. This increases the methane concentration in the biogas BG, allowing the biogas BG to be used for a variety of purposes.

[0036] Furthermore, in the biomass treatment device 1A, even after the carbon dioxide produced by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria is consumed in the CO2-reducing methane production reaction by the hydrogen-assimilating methanogens, methane is still produced by the CO2-reducing methane production reaction by the hydrogen-assimilating methanogens using as substrates the hydrogen derived from the hydrogen-containing gas supplied by the fine bubble supply unit 3 and the carbon dioxide derived from the carbon dioxide-containing gas supplied by the gas supply unit 4. Therefore, the amount of methane produced can be increased under the condition that the hydrogen, carbon dioxide, and other nutrients necessary for the growth of the hydrogen-assimilating methanogens are satisfied.

[0037] Second Embodiment 2 is a schematic diagram showing the general configuration of a biomass processing device 1B according to a second embodiment. In the second embodiment, components that are the same as or similar to those in the first embodiment are simply given the same reference numerals in the drawing, and detailed descriptions thereof will be omitted. The following description will focus on the parts unique to the second embodiment (the same applies to the third to sixth embodiments described below).

[0038] In the biomass processing apparatus 1B of the second embodiment, a gas supply unit 6 is arranged so that a carbon dioxide-containing gas is supplied to the fermentation liquor FL as fine bubbles together with a hydrogen-containing gas. The gas supply unit 6 includes a CO2 gas supply source 28 and a gas supply pipe 29, which are arranged in this order from the upstream side to the downstream side of the gas flow. The CO2 gas supply source 28 can be the same as the CO2 gas supply source 21, and the carbon dioxide-containing gas can be the same as the carbon dioxide-containing gas. The upstream end of the gas supply pipe 29 is connected to the CO2 gas supply source 28, and the downstream end of the gas flow is connected to the gas supply pipe 12.

[0039] In the biomass processing apparatus 1B of the second embodiment, carbon dioxide-containing gas from the gas supply unit 6 is supplied to the fine bubble generator 13 via the gas supply pipe 29, and the carbon dioxide-containing gas is supplied as fine bubbles to the fermentation liquor FL in addition to the hydrogen-containing gas supplied by the fine bubble supply unit 3. As a result, the fine bubbles contain carbon dioxide-containing gas in addition to the hydrogen-containing gas, thereby increasing the dissolution rate of the hydrogen-containing gas and carbon dioxide-containing gas into the fermentation liquor FL. As a result, even after the carbon dioxide generated by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria is consumed in the CO2-reducing methane production reaction by the hydrogen-assimilating methanogens, the hydrogen and carbon dioxide required for the CO2-reducing methane production reaction by the hydrogen-assimilating methanogens, which use hydrogen and carbon dioxide as substrates, can be quickly supplied. Therefore, the CO2-reducing methane production reaction by the hydrogen-assimilating methanogens continues to occur efficiently, improving methane production efficiency.

[0040] Third Embodiment Figure 3 is a schematic diagram showing the overall configuration of a biomass processing device 1C of the third embodiment. As shown in Figure 3, in the biomass processing device 1C of the third embodiment, a return pipe 31, shown by a solid line in the figure, which is arranged in a form branching off from a gas exhaust pipe 25, is connected to a fine bubble generator 13. A circulation circuit 30 is formed by the storage tank 2, the gas exhaust pipe 25, the return pipe 31, and the fine bubble generator 13. The rest of the configuration is the same as that of the biomass processing device 1A of the first embodiment.

[0041] It goes without saying that the biomass processing device 1C of the third embodiment can achieve the same effects as the biomass processing device 1A of the first embodiment. Furthermore, in the biomass processing device 1C of the third embodiment, a portion of the biogas BG extracted from the inside of the storage tank 2 through the gas exhaust pipe 25 is returned to the inside of the storage tank 2 through the return pipe 31 and the fine bubble generator 13 and circulated by the circulation circuit 30. As a result, methane is produced by a CO2-reducing methanogenesis reaction by hydrogen-assimilating methanogens using the hydrogen and carbon dioxide remaining in the biogas BG as substrates, and the methane concentration in the biogas BG can be further increased.

[0042] 3, a return pipe 31 arranged branching from the gas discharge pipe 25 may be connected to the gas inlet pipe 22, and a circulation circuit 30 may be formed by the storage tank 2, the gas discharge pipe 25, the return pipe 31, and the gas inlet pipe 22 (two circulation circuits 30 may be formed by connecting the return pipe 31 to both the gas inlet pipe 22 and the fine bubble generator 13). Even with this configuration, a portion of the biogas BG is returned to the gas supply unit 4 and circulated, and methane is produced by a CO2-reducing methanogenesis reaction by hydrogen-assimilating methanogens using the hydrogen and carbon dioxide remaining in the biogas BG as substrates, thereby further increasing the methane concentration in the biogas BG.

[0043] Fourth Embodiment Fig. 4 is a schematic diagram showing the overall configuration of a biomass processing apparatus 1D of the fourth embodiment. As shown in Fig. 4, in the biomass processing apparatus 1D of the fourth embodiment, a return pipe 31 branching from a gas exhaust pipe 25 is connected to a fine bubble generator 13. A circulation circuit 30 is formed by the storage tank 2, the gas exhaust pipe 25, the return pipe 31, and the fine bubble generator 13. The rest of the configuration is the same as that of the biomass processing apparatus 1B of the second embodiment.

[0044] It goes without saying that the biomass processing device 1D of the fourth embodiment can achieve the same effects as the biomass processing device 1B of the second embodiment. Furthermore, in the biomass processing device 1D of the fourth embodiment, a portion of the biogas BG extracted from the inside of the storage tank 2 through the gas discharge pipe 25 is returned to the inside of the storage tank 2 through the return pipe 31 and the fine bubble generator 13 and circulated by the circulation circuit 30. As a result, methane is produced by a CO2-reducing methanogenesis reaction by hydrogen-assimilating methanogens using the hydrogen and carbon dioxide remaining in the biogas BG as substrates, and the methane concentration in the biogas BG can be further increased.

[0045] Fifth Embodiment FIG. 5 is a schematic diagram showing the overall configuration of a biomass processing apparatus 1E of the fifth embodiment. As shown in FIG. 5, in the biomass processing apparatus 1E of the fifth embodiment, a pressure regulating valve 35 is provided in the gas exhaust pipe 25. The pressure regulating valve 35 opens when the pressure inside the storage tank 2 exceeds a predetermined pressure, and closes when the pressure is below the predetermined pressure, thereby maintaining the inside of the storage tank 2 in a pressurized state at the predetermined pressure. The remaining configuration is the same as that of the biomass processing apparatus 1A of the first embodiment. Note that in this example, the pressure regulating valve 35 is provided to enable the inside of the storage tank 2 to be pressurized, but this is not limited thereto. For example, the inside of the storage tank 2 may be pressurized by pumping a gas such as a hydrogen-containing gas or a carbon dioxide-containing gas into the storage tank 2 (this also applies to the sixth embodiment described below).

[0046] It goes without saying that the biomass processing device 1E of the fifth embodiment can achieve the same effects as the biomass processing device 1A of the first embodiment. Furthermore, in the biomass processing device 1E of the fifth embodiment, by pressurizing the inside of the storage tank 2, it is possible to prevent the hydrogen and carbon dioxide once dissolved in the fermentation liquor FL from being released from the fermentation liquor FL, and it is possible to further improve the dissolution rate of the hydrogen-containing gas and the carbon dioxide-containing gas into the fermentation liquor FL.

[0047] Sixth Embodiment Figure 6 is a schematic diagram showing the overall configuration of a biomass processing device 1F of the sixth embodiment. As shown in Figure 6, in the biomass processing device 1F of the sixth embodiment, as in the fifth embodiment, a pressure adjustment valve 35 is provided in the gas exhaust pipe 25, and the inside of the storage tank 2 is maintained in a pressurized state at a predetermined pressure by opening and closing the pressure adjustment valve 35. The rest of the configuration is the same as that of the biomass processing device 1B of the second embodiment.

[0048] It goes without saying that the biomass processing device 1F of the sixth embodiment can achieve the same effects as the biomass processing device 1B of the second embodiment. Furthermore, in the biomass processing device 1F of the sixth embodiment, as in the fifth embodiment, by pressurizing the inside of the storage tank 2, it is possible to prevent the hydrogen and carbon dioxide once dissolved in the fermentation liquor FL from being released from the fermentation liquor FL, and it is also possible to further improve the dissolution rate of the hydrogen-containing gas and the carbon dioxide-containing gas into the fermentation liquor FL.

[0049] The above describes the biomass processing device of the present invention based on several embodiments, but the present invention is not limited to the configurations described in the above embodiments, and the configuration can be changed as appropriate within the scope of the spirit of the invention, such as by appropriately combining the configurations described in each embodiment. [Industrial Applicability]

[0050] The biomass treatment device of the present invention can be used, for example, to produce fuel for city gas, gas engines, and the like. [Explanation of symbols]

[0051] 1A~1F Biomass processing equipment 2. Reservoir 3 Fine bubble supply unit 4 Gas supply section 30 Circulation circuit 35 Pressure Regulating Valve

Claims

1. A biomass treatment device that ferments biomass to produce biogas, A storage tank for storing a fermentation liquid obtained by fermenting the biomass; a fine bubble supply unit that supplies hydrogen-containing gas to the fermentation liquid as fine bubbles; A biomass treatment device comprising:

2. The biomass treatment device according to claim 1 , further comprising a gas supply unit that supplies a carbon dioxide-containing gas to the fermentation liquid.

3. The biomass treatment device according to claim 1 , wherein the fine bubbles further contain a carbon dioxide-containing gas.

4. The biomass treatment device according to any one of claims 1 to 3, further comprising a circulation circuit for returning a portion of the biogas to the fine bubble supply unit and circulating the same.

5. The biomass treatment apparatus according to claim 2, further comprising a circulation circuit for returning a part of the biogas to the gas supply unit and circulating the same.

6. The biomass treatment device according to any one of claims 1 to 3, wherein the storage tank is configured so that the inside thereof can be pressurized.

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