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 plug flow-type fermentation tank 2 that stores a fermentation liquid FL in which the biomass is fermented while undergoing flow; and a gas supply part 4 that supplies a hydrogen-containing gas to the fermentation liquid FL, wherein it is preferable to provide a recycling device 6 for filtering the fermentation liquid FL, discharging a filtrate, and returning a filtered material to the fermentation tank 2.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 smaller molecules by hydrolytic bacteria and other bacteria, resulting in higher fatty acids, amino acids, and sugars. The smaller organic compounds are then broken down by acidogenic bacteria into hydrogen, CO2, 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 through anaerobic fermentation as described above, a plug flow reactor is known that performs a solubilization step and a methane fermentation step while flowing biomass laterally in a fermentation tank (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-84508 Summary of the Invention [Problem to be solved by the invention]

[0006] In the biomass treatment device of Patent Document 1, the biogas contains CO2, which is inevitably produced by the decomposition of low-molecular-weight organic matter by acid-producing bacteria. This means that the methane concentration in the generated biogas is low, at approximately 50 to 60%, and there is a problem in 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 plug flow type fermenter that stores a fermentation liquid obtained by fermenting the biomass while flowing; a gas supply unit that supplies a hydrogen-containing gas to the fermentation liquid; The purpose is to provide the following.

[0009] In this biomass treatment device, methane is ultimately produced from acetic acid, hydrogen, and CO2 by methanogens. The reaction that produces methane using acetic acid as a substrate, as exemplified by Patent Document 1, is an acetic acid decomposition methanogenesis reaction, which is carried out by acetic acid decomposition methanogens. On the other hand, the reaction that produces methane using hydrogen and CO2 as substrates is a CO2 reduction methanogenesis reaction, which is carried out by hydrogen-utilizing methanogens. In this biomass treatment device, a hydrogen-containing gas is supplied to the fermentation liquor in the fermenter by the gas supply unit. Therefore, in addition to the hydrogen produced by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria, hydrogen derived from the hydrogen-containing gas supplied by the gas supply unit is contained in the fermentation liquor. Then, using the hydrogen derived from the hydrogen-containing gas and CO2 inevitably produced by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria as substrates, methane is produced by a CO2 reduction methanogenesis reaction carried out by hydrogen-utilizing methanogens. In this way, CO2 can be reduced by hydrogen, increasing the methane concentration in the biogas, thereby enabling the biogas to be used for a variety of purposes.

[0010] In the biomass treatment device according to the present invention, The fermenter has an acid fermentation zone and a methane fermentation zone, The gas supply unit preferably supplies the hydrogen-containing gas to the methane fermentation zone.

[0011] In this biomass treatment device, the fermenter has an acid fermentation zone and a methane fermentation zone. In the acid fermentation zone, acid-producing bacteria decompose organic matter into lower organic acids such as butyric acid, propionic acid, and acetic acid. Meanwhile, in the methane fermentation zone, methanogens produce methane from acetic acid, hydrogen, and CO2. However, if hydrogen-containing gas from the gas supply unit is supplied to the acid fermentation zone in the fermenter, hydrogen from the hydrogen-containing gas supplied by the gas supply unit accumulates in addition to the hydrogen by-produced in the acid fermentation zone, increasing the hydrogen partial pressure. This can result in product inhibition, preventing the acetic acid production reaction from proceeding, and ultimately reducing the methane production rate. Therefore, in this biomass treatment device, hydrogen-containing gas from the gas supply unit is supplied to the methane fermentation zone in the fermenter. This avoids product inhibition in the acid fermentation zone. As a result, in the methane fermentation zone, methane is produced by an acetic acid decomposition methanogenesis reaction using acetic acid as a substrate, and methane is also produced by a CO2 reduction methanogenesis reaction using hydrogen and CO2 as substrates, thereby improving the efficiency of methane production.

[0012] In the biomass treatment device according to the present invention, The fermenter preferably has a hydrogen supply area to which the hydrogen-containing gas is supplied and a hydrogen non-supply area to which the hydrogen-containing gas is not supplied.

[0013] In this biomass treatment device, methane is produced in the hydrogen supply area by a CO2-reducing methanogen reaction using hydrogen derived from the hydrogen-containing gas supplied by the gas supply unit and CO2, which is inevitably produced by the acid-producing bacteria as a substrate. Meanwhile, in the non-hydrogen supply area, no hydrogen-containing gas is supplied, and the acid-producing bacteria carry out an acid-producing reaction to decompose organic matter into lower organic acids such as butyric acid, propionic acid, and acetic acid. In this way, CO2 can be reduced with hydrogen in the hydrogen supply area to increase the methane concentration in the biogas, while product inhibition can be avoided in the non-hydrogen supply area, improving methane production efficiency.

[0014] In the biomass treatment device according to the present invention, It is preferable that a partition be disposed in the fermenter to separate the portion containing the fermentation liquid into an upstream side and a downstream side in the flow direction so that the fermentation liquid can flow in the flow direction of the biomass.

[0015] In this biomass treatment device, an acid production reaction occurs upstream of the fermentation liquor-containing biomass flow direction separated by a partition wall, while a methane production reaction occurs downstream of the fermentation liquor-containing biomass flow direction. Under conditions of constant fermentation liquor movement from upstream to downstream, the acid production reaction and the methane production reaction occur in tandem. Furthermore, by supplying hydrogen-containing gas from a gas supply unit downstream of the partition wall where the methane production reaction occurs, methane is produced by a CO2-reducing methane production reaction catalyzed by hydrogen-utilizing methanogens using hydrogen derived from the hydrogen-containing gas supplied by the gas supply unit and CO2, which is inevitably produced by the acid-producing bacteria during decomposition of low-molecular-weight organic matter, as substrates. The partition wall prevents hydrogen from the hydrogen-containing gas supplied downstream of the partition wall from moving upstream of the partition wall, thereby suppressing product inhibition in the acid fermentation zone. This improves methane production efficiency.

[0016] In the biomass treatment device according to the present invention, It is preferable that the position of the partition wall in the flow direction of the biomass is adjustable.

[0017] According to the biomass treatment device of this configuration, an acid production reaction takes place upstream in the flow direction of the biomass separated by the partition in the part where the fermentation liquid is stored, while a methane production reaction takes place downstream in the flow direction of the biomass separated by the partition. By adjusting the position of the partition in the flow direction of the biomass, the ratio of the acid production reaction upstream of the partition and the methane production reaction downstream of the partition can be easily adjusted.

[0018] In the biomass treatment device according to the present invention, The fermenter has a biogas storage section that stores the biogas, It is preferable that a circulation circuit be provided to supply a portion of the biogas in the biogas storage unit to the gas supply unit and circulate the gas therein.

[0019] According to the biomass processing device of this configuration, the generated biogas is stored in the biogas storage section, and a portion of the biogas in the biogas storage section is returned to the gas supply section and circulated, thereby converting the CO2 remaining in the biogas into methane, thereby further increasing the methane concentration in the biogas.

[0020] In the biomass treatment device according to the present invention, The biogas storage section preferably includes a plurality of compartments arranged in communication with each other along the direction of flow of the biomass.

[0021] With this biomass processing device, biomass gas is sequentially introduced into multiple compartments from the upstream side to the downstream side in the flow direction of the biomass, and a portion of the biogas in each compartment is supplied to the gas supply section via a circulation circuit and circulated, thereby gradually increasing the methane concentration in the biogas.

[0022] In the biomass treatment device according to the present invention, It is preferable to provide a recycling device for filtering the fermentation liquid, discharging the filtrate, and returning the filtered matter to the fermenter.

[0023] With this biomass treatment device, the filtrate (digestion liquid) discharged after filtering the fermentation liquid can be effectively used, for example, as liquid fertilizer. Furthermore, the filtered residue, which contains a large amount of methane bacteria, is returned to the fermenter for reuse. This maintains a high concentration of methane bacteria in the fermenter, allowing for efficient methane fermentation. [Brief explanation of the drawings]

[0024] [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. [Figure 7] FIG. 7 is a schematic diagram showing a schematic configuration of a biomass treatment apparatus according to the seventh embodiment. [Figure 8] FIG. 8 is a diagram showing the state of diffusion of hydrogen-containing gas in the methane fermentation zone in the biomass treatment device of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] 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. In the following embodiments, a horizontal plug flow biomass treatment device 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 configurations shown in the following embodiments and drawings. For example, the present invention can be applied to a vertical plug flow biomass treatment device. Furthermore, the present invention can be applied to both dry and wet biomass treatment devices.

[0026] First Embodiment <Overall structure> FIG. 1 is a schematic diagram showing the overall configuration of a biomass processing device 1A of a first embodiment. As shown in FIG. 1, the biomass processing device 1A is a plug-flow fermentation device (in this example, a plug-flow horizontal fermentation device) equipped with a fermenter 2, a biomass supply unit 3, a gas supply unit 4, a biogas recovery unit 5, and a recycling device 6 of any configuration. When the fermenter is a dry type, the solid concentration in the fermenter 2 is adjusted to approximately 8 to 40% by weight, and biogas is produced by methane fermentation of the biomass in a high-temperature environment (45 to 65°C). Dry fermentation devices include dry horizontal fermentation devices and dry vertical fermentation devices. Because it is necessary to ensure fluidity within the fermenter 2, dry horizontal fermentation devices are suitable for processing a relatively low solid concentration in the fermenter 2 of approximately 8 to 15% by weight. In contrast, dry vertical fermentation devices are capable of processing a high solid concentration of approximately 15 to 40% by weight. On the other hand, when the fermentation apparatus is a wet type, whether horizontal or vertical, the solid concentration in the fermentation tank 2 is adjusted to around 10% by weight or less, and biogas is produced by fermenting the biomass in a medium temperature environment (30 to 45°C) or a high temperature environment (45 to 65°C).

[0027] <Fermentation tank> The fermenter 2 has a body 10 that is a horizontally elongated tube (horizontally long cylindrical shape) with its axis (not shown) oriented horizontally, a first end face 11 that closes one end of the body 10, and an opposite end face 12 that closes the other end of the body 10. The fermenter 2 is a so-called plug flow type fermenter, and is configured to store (contain) a fermentation liquid FL that is fermented while biomass is flowing from the first end face 11 to the opposite end face 12, and to fill the space above the liquid level of the fermentation liquid FL with biogas BG. A stirring paddle (not shown) that gently stirs the fermentation liquid FL is provided inside the fermenter 2 to promote degassing from the fermentation liquid FL.

[0028] The fermenter 2 has a biogas storage section 70 that stores the biogas BG. That is, the biogas storage section 70 that stores the biogas BG is formed in the space between the inner circumferential surface of the upper region of the body section 10 of the fermenter 2 and the liquid surface of the fermentation liquid FL. In this example, the biogas storage section 70 is formed by the inner circumferential surface of the upper region of the body section 10 and the upper parts of the one side end surface section 11 and the other side end surface section 12.

[0029] <Biomass Supply Department> The biomass supply unit 3 includes a pressure-feeding unit 15 and a biomass supply pipe 16. The pressure-feeding unit 15 includes, for example, a pump and a control valve for controlling the feed rate and pressure, although detailed illustrations are omitted. The biomass supply pipe 16 connects the pressure-feeding unit 15 to a biomass supply port 17 provided on one end surface 11. Before the biomass supply unit 3, the organic waste used as raw material is subjected to pretreatment equipment (not shown) to homogenize the raw material by removing foreign matter and adjust the moisture content to a level suitable for methane fermentation. The pretreated organic waste is then forced into the fermenter 2 through the biomass supply port 17 by the biomass supply unit 3. The forced organic waste is then swept toward a digester liquid discharge port 18 provided on the other end surface 12. The organic waste gradually moves from the biomass supply port 17 toward the digestive liquid discharge port 18, undergoing hydrolysis, acid production, and methane production reactions, and is converted into biogas.The fermentation liquid (methane fermentation digestive liquid) remaining after the biogas BG is extracted is discharged from the digestive liquid discharge port 18.

[0030] <Gas supply section> The gas supply unit 4 supplies a hydrogen-containing gas to the fermentation liquid FL in the fermenter 2. The hydrogen-containing gas refers to 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%.

[0031] The gas supply unit 4 includes a gas supply source 21 and an aeration unit 22. Although detailed description using drawings is omitted, the gas supply source 21 includes a hydrogen storage unit that stores hydrogen gas under high pressure, a pressure reducing valve that reduces the pressure of the high-pressure hydrogen gas from the hydrogen storage unit, and the like. 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 power, and surplus hydrogen from a nearby petrochemical plant. Meanwhile, the aeration unit 22 is disposed at the bottom of the body 10 so as to be able to diffuse the hydrogen-containing gas into the fermenter 2. In this example, the aeration unit 22 is disposed so as to extend in the longitudinal direction (the direction in which the one-side end surface portion 11 and the other-side end surface portion 12 are disposed) and the circumferential direction of the body 10 so as to be able to diffuse the hydrogen-containing gas throughout the entire interior of the fermenter 2, and is connected to the gas supply source 21 via a gas supply pipe 23. Here, the aeration unit 22 is not particularly limited as long as it can diffuse the hydrogen-containing gas supplied from the gas supply source 21 via the gas supply pipe 23 into the fermentation liquid FL, and for example, an aeration pipe with required holes, a membrane-type aeration pipe, or a porous so-called air stone can be used.

[0032] <Biogas Recovery Section> A gas vent port 24 is provided in a predetermined position in the upper region of the body 10 of the fermenter 2 (in this example, a position close to the other end surface 12, but this is not limited to this position). The biogas recovery section 5, which extracts and recovers the biogas BG from the biogas storage section 70 through the gas vent port 24, is equipped with a gas discharge pipe 25 and a gas withdrawal section 26. The upstream end of the gas discharge pipe 25 is connected to the gas vent port 24 so that the biogas BG can be discharged outside the tank, and the downstream end of the gas flow is connected to a gas holder 27. The gas withdrawal section 26 is disposed midway along the gas discharge pipe 25. The biogas BG withdrawn from the fermenter 2 through the gas discharge pipe 25 by the gas withdrawal section 26 is temporarily stored in the gas holder 27 and then effectively utilized. A gas purification device may be connected to the downstream gas flow side of the gas holder 27. Gas purification equipment includes equipment that removes hydrogen sulfide from biogas BG, moisture removal equipment, equipment that further reduces CO2 from biogas BG using pressure swing adsorption (PSA), membrane separation, high-pressure water absorption, chemical absorption, physical absorption, etc., and siloxane removal equipment.

[0033] <Reuse equipment> The recycling apparatus 6 includes a reflux pipe 31, a pressure pump 32, and a solid-liquid separator 33. The reflux pipe 31 is disposed in a manner that connects the digestion liquid discharge port 18 provided on the other end surface 12 of the fermenter 2 to the biomass supply pipe 16. The pressure pump 32 is disposed in the reflux pipe 31 at a position close to the digestion liquid discharge port 18. The solid-liquid separator 33 is disposed in the reflux pipe 31 so as to be located between the pressure pump 32 and the biomass supply pipe 16. The solid-liquid separator 33 can be a filtration membrane such as a microfiltration membrane (MF membrane) or an ultrafiltration membrane (UF membrane), and examples of the membrane shape include a flat membrane and a hollow fiber membrane. In the recycling apparatus 6, the pressure pump 32 is operated to send the fermentation liquid (methane fermentation digestion liquid) FL remaining after the biogas BG is extracted to the solid-liquid separator 33. The solid-liquid separator 33 filters the methane fermentation digested liquid fed from the pressure pump 32 to separate it into a filtrate and a filtrate cake. The filtrate cake is returned to the fermenter 2 via the reflux pipe 31, the biomass supply pipe 16, and the biomass supply port 17 for reuse. Meanwhile, the filtrate (filtered digested liquid) is discharged via a filtrate discharge pipe 36 connected to a filtrate discharge port of the solid-liquid separator 33. The discharged filtered digested liquid is recovered in a digested liquid recovery section 37 and effectively utilized, for example, as liquid fertilizer. In this embodiment, an example has been shown in which a device that separates solids and liquids using a filtration membrane such as an MF membrane or an UF membrane is used as the solid-liquid separator 33. However, the present invention is not limited to this, and devices such as a rotary drum, a drum screen, a belt press, a screw press, a belt thickener, a flotation separator, and a sedimentation separator can also be used. In this example, the entire amount of the fermentation liquid (methane fermentation digested liquid) FL remaining after the biogas BG is removed is sent to the solid-liquid separator 33, but the present invention is not limited to this, and a portion of the methane fermentation digested liquid may be returned to the fermenter 2 via the biomass supply pipe 16. In another embodiment, a portion of the methane fermentation digested liquid supplied to the recycling device 6 or a portion of the methane fermentation digested liquid concentrated in the recycling device 6 is incinerated to recover heat.

[0034] In the biomass treatment apparatus 1A configured as described above, organic waste is forced into the interior of the fermenter 2 from the biomass supply port 17 by the biomass supply unit 3. Furthermore, a hydrogen-containing gas is blown into the fermentation liquid FL in the fermenter 2 from the gas supply unit 4. Furthermore, to promote degassing from the fermentation liquid FL, the fermentation liquid FL is gently stirred by a stirring paddle (not shown).

[0035] In the fermenter 2, the organic waste forced into the interior through the biomass supply port 17 is swept toward the digested liquid outlet 18. As the organic waste gradually moves from the biomass supply port 17 toward the digested liquid outlet 18, it undergoes hydrolysis, acid production, and methane production reactions and is converted into biogas BG, and the fermentation liquid (methane fermentation digested liquid) FL that remains after the biogas BG is removed is discharged from the digested liquid outlet.

[0036] The reaction that produces methane using acetic acid as a substrate, as exemplified by Patent Document 1, is an acetic acid decomposition methanogenesis reaction, which is carried out by acetic acid decomposing methanogens. On the other hand, the reaction that produces methane using hydrogen and CO2 as substrates is a CO2 reduction methanogenesis reaction, which is carried out by hydrogen-utilizing methanogens.

[0037] In the biomass processing apparatus 1A of the first embodiment, the gas supply unit 4 supplies a hydrogen-containing gas to the fermentation liquor FL in the fermenter 2. Therefore, in addition to the hydrogen produced by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria, the fermentation liquor FL contains hydrogen derived from the hydrogen-containing gas supplied by the gas supply unit 4. Using the hydrogen derived from the hydrogen-containing gas and CO2, which is inevitably produced by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria, as substrates, methane is produced by a CO2 reduction methanogenesis reaction carried out by hydrogen-assimilating methanogens. In this way, CO2 is reduced by hydrogen, thereby increasing the methane concentration in the biogas BG. The biogas BG produced by methane fermentation accumulates in the biogas storage unit 70 above the liquid level of the fermentation liquor FL stored in the fermenter 2 and is recovered by the biogas recovery unit 5 for effective utilization.

[0038] The fermentation liquid (methane fermentation digested liquid) FL discharged from the inside of the fermenter 2 through the digested liquid outlet 18 is sent to the solid-liquid separator 33 by the pressure pump 32 and separated into a filtrate and a filtrate. The filtrate is returned to the fermenter 2. The filtrate contains a large amount of methane bacteria, and is reused by returning it to the fermenter 2, thereby maintaining a high concentration of methane bacteria and enabling efficient methane fermentation. Meanwhile, the filtrate (filtered digested liquid) is recovered in the digested liquid recovery section 37 and is effectively utilized, for example, as liquid fertilizer. As mentioned above, the recycling device 6 has an optional configuration, and therefore devices such as the pressure pump 32 and the solid-liquid separator 33 may be omitted in some cases.

[0039] 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 denoted by the same reference numerals in the figure, and detailed descriptions thereof will be omitted. The following description will focus on the components unique to the second embodiment.

[0040] In the biomass treatment apparatus 1B of the second embodiment, the fermenter 2 has an acid fermentation zone 41 and a methane fermentation zone 42. The acid fermentation zone 41 is located upstream of the portion of the fermenter 2 where the fermentation liquor FL is stored, and the methane fermentation zone 42 is located downstream of the portion of the fermenter 2 where the fermentation liquor FL is stored. That is, the portion of the fermenter 2 where the fermentation liquor FL is stored is divided into a predetermined upstream region and a predetermined downstream region in the flow direction of the organic waste (biomass) (the direction from the one end surface 11 to the other end surface 12). The predetermined upstream region is the acid fermentation zone 41, and the predetermined downstream region is the methane fermentation zone 42. In the acid fermentation zone 41, an acid production reaction is carried out by acid-producing bacteria to decompose organic matter into lower organic acids such as butyric acid, propionic acid, and acetic acid. In the methane fermentation zone 42, a methane production reaction is carried out by methanogens to produce methane from acetic acid, hydrogen, and CO2.

[0041] Furthermore, in the biomass processing apparatus 1B, the gas supply unit 4 supplies hydrogen-containing gas to the methane fermentation zone 42. That is, in the gas supply unit 4, the aeration unit 22 is disposed so as to extend in the longitudinal and circumferential directions of the trunk portion 10 at the bottom of the portion of the trunk portion 10 corresponding to the methane fermentation zone 42 so that the hydrogen-containing gas can be diffused only into the methane fermentation zone 42 in the fermenter 2. In this way, the hydrogen-containing gas is supplied substantially only to the methane fermentation zone 42. Note that, because the length of the methane fermentation zone 42 can vary depending on the fermentation conditions of the biomass, the aeration unit 22 may be disposed over the entire bottom of the trunk portion 10, and the hydrogen-containing gas may be diffused from the aeration unit 22 according to the length of the methane fermentation zone 42.

[0042] However, if the hydrogen-containing gas from the gas supply unit 4 is supplied to the acid fermentation zone 41, in addition to the hydrogen produced as a by-product in the acid production reaction in the acid fermentation zone 41, hydrogen derived from the hydrogen-containing gas supplied by the gas supply unit 4 will accumulate, causing an increase in hydrogen partial pressure. As a result, the acetic acid production reaction will not proceed due to product inhibition, and ultimately there is a risk of a decrease in the methane production rate.

[0043] Therefore, in the biomass processing apparatus 1B, the hydrogen-containing gas from the gas supply unit 4 is supplied to the methane fermentation zone 42, rather than to the acid fermentation zone 41. This makes it possible to avoid product inhibition in the acid fermentation zone 41, and in the methane fermentation zone 42, methane is produced by an acetic acid decomposition methanogenesis reaction using acetic acid as a substrate, and methane is also produced by a CO2 reduction methanogenesis reaction using hydrogen and CO2 as substrates. Therefore, the methane production efficiency can be improved compared to the biomass processing apparatus 1A of the first embodiment.

[0044] Third Embodiment 3 is a schematic diagram showing the overall configuration of a biomass processing apparatus 1C of the third embodiment. In the biomass processing apparatus 1C of the third embodiment, a return pipe 51 branching off from the gas exhaust pipe 25 is connected to the aeration unit 22. A circulation circuit 50 is formed by the fermenter 2, the gas exhaust pipe 25, the return pipe 51, and the aeration unit 22. The rest of the configuration is the same as that of the biomass processing apparatus 1B of the second embodiment.

[0045] It goes without saying that the biomass processing device 1C of the third embodiment can achieve the same effects as the biomass processing device 1B of the second embodiment. Furthermore, in the biomass processing device 1C of the third embodiment, a portion of the biogas BG extracted by the gas extraction unit 26 through the gas exhaust pipe 25 from the inside of the fermenter 2 is returned to the inside of the fermenter 2 through the return pipe 51 and the aeration unit 22 and circulated by the circulation circuit 50. As a result, CO2 remaining in the biogas BG is converted to methane, and the methane concentration in the biogas BG can be further increased.

[0046] Fourth Embodiment 4 is a schematic diagram showing the overall configuration of a biomass processing apparatus 1D of the fourth embodiment. In the biomass processing apparatus 1D of the fourth embodiment, the fermenter 2 has a biogas storage section 70 that stores biogas BG produced in the methane fermentation zone 42. The biogas storage section 70 includes multiple (three in this example) compartments 71-73 that are arranged in communication along the flow direction of organic waste (biomass) (hereinafter referred to as the "biomass flow direction"). That is, in the space between the inner circumferential surface of the upper region of the body section 10 and the liquid surface of the fermentation liquid FL, a partition plate 60 is attached to the inner circumferential surface of the body section 10 above the boundary between the acid fermentation zone 41 and the methane fermentation zone 42, and is arranged so as to face one end surface section 11. Between the partition wall plate 60 and the other-side end surface portion 12, a plurality of partition walls (a first partition wall 61, a second partition wall 62) are attached to the inner peripheral surface of the body portion 10 at predetermined intervals in the longitudinal direction (biomass flow direction) of the body portion 10 so as to partition the space between the inner peripheral surface in the upper region of the body portion 10 and the liquid surface of the fermentation liquid FL. A first partition chamber 71 is formed by the inner peripheral surface in the upper region of the body portion 10, the partition wall plate 60, and the first partition wall 61, a second partition chamber 72 is formed by the inner peripheral surface in the upper region of the body portion 10, the first partition wall 61, and the second partition wall 62, and a third partition chamber 73 is formed by the inner peripheral surface in the upper region of the body portion 10, the second partition wall 62, and the other-side end surface portion 12. The first compartment chamber 71, the second compartment chamber 72 and the third compartment chamber 73 are arranged in a connected state in the biogas storage section 70 so that the biogas BG flows in the direction from the first compartment chamber 71 to the third compartment chamber 73, or from the third compartment chamber 73 to the first compartment chamber 71, or so that the biogas BG flows in both directions.

[0047] The method for communicating the first compartment 71, the second compartment 72, and the third compartment 73 is not particularly limited, and examples thereof include providing vent holes in the first partition plate 61 and the second partition plate 62, or disposing a communication pipe inside or outside the body 10 that connects the compartments 71 to 73 in communication with each other. In this example, the first compartment 71, the second compartment 72, and the third compartment 73 are communicated by providing vent holes in the first partition plate 61 and the second partition plate 62. In addition, by providing a vent hole in the partition plate 60, the compartment between the one side end surface 11 and the partition plate 60 and the first compartment 71 are communicated with each other, so that gas from the acid fermentation zone 41 does not stagnate in the compartment between the one side end surface 11 and the partition plate 60.

[0048] The relative sizes of the first compartment chamber 71, the second compartment chamber 72, and the third compartment chamber 73 are not particularly limited, but for example, as shown in Fig. 4, the sizes of the compartment chambers 71 to 73 can be made smaller toward the downstream side in the biomass flow direction. By doing so, even when methane fermentation progresses in the methane fermentation zone 42 from the upstream side to the downstream side in the biomass flow direction and the amount of biogas BG generated gradually increases, it is possible to uniformize the amount of biogas BG stored in each of the compartment chambers 71 to 73. In this embodiment, an example is shown in which the number of compartment chambers (first compartment chamber 71 to third compartment chamber 73) is three, but the number of compartment chambers is not limited, and there may be two or four or more compartment chambers.

[0049] In the upper region of the body of the fermentation tank 2, a first gas outlet 75 is provided to allow biogas BG to be extracted from the first compartment 71 to the outside of the tank, a second gas outlet 76 is provided to allow biogas BG to be extracted from the second compartment 72 to the outside of the tank, and a third gas outlet 77 is provided separately from the gas vent port 24 to allow biogas BG to be extracted from the third compartment 73 to the outside of the tank.

[0050] In the fermenter 2, the area between the first compartment chamber 71 and the second compartment chamber 72 and the aeration unit 22 is the methane fermentation zone 42, which is also a hydrogen supply area 91. In addition, in the fermenter 2, the area between the third compartment chamber 73 and the aeration unit 22 is the methane fermentation zone 42, which is also a hydrogen non-supply area 92.

[0051] The gas supply unit 4 supplies hydrogen-containing gas to the hydrogen supply area 91 while not supplying hydrogen-containing gas to the hydrogen non-supply area 92. For example, in the aeration unit 22, a diffusion pipe or the like is arranged, and the aeration pipe or the like is connected by piping, and control valves or the like are arranged at key points in the piping.

[0052] The first gas outlet 75 and the aeration unit 22 are connected by a first return pipe 81a. The second gas outlet 76 and the aeration unit 22 are connected by a second return pipe 81b. The third gas outlet 77 and the aeration unit 22 are connected by a third return pipe 81c. A first circulation circuit 80a is formed by the fermenter 2, the first return pipe 81a, and the aeration unit 22, a second circulation circuit 80b is formed by the fermenter 2, the second return pipe 81b, and the aeration unit 22, and a third circulation circuit 80c is formed by the fermenter 2, the third return pipe 81c, and the aeration unit 22. The biogas recovery unit 5 is connected to the gas vent 24, as in the biomass processing apparatus 1C of the third embodiment.

[0053] A portion of the biogas BG accumulated in the first compartment chamber 71, which is located upstream in the biomass flow direction among the multiple compartment chambers (first compartment chamber 71 to third compartment chamber 73), is supplied to the aeration unit 22 via the first return pipe 81a. In this way, a portion of the biogas BG in the first compartment chamber 71 is circulated by the first circulation circuit 80a from the first compartment chamber 71 through the first return pipe 81a, the aeration unit 22, the methane fermentation zone 42, and the hydrogen supply area 91 back into the biogas storage unit 70 (first compartment chamber 71). As a result, CO2 remaining in the biogas BG in the first compartment chamber 71 is converted to methane, and the methane concentration in the biogas BG is increased.

[0054] The biogas BG in the first compartment 71, which has an increased methane concentration due to circulation through the first circulation circuit 80a, passes through the vent hole in the first partition plate 61 and is introduced into the second compartment 72, which is located downstream in the biomass flow direction. Similar to the circulation and concentration of the biogas BG in the first compartment 71, a portion of the biogas BG in the second compartment 72 is supplied to the aeration unit 22 via the second return pipe 81b. Thus, a portion of the biogas BG in the second compartment 72 is circulated by the second circulation circuit 80b from the second compartment 72 through the second return pipe 81b, the aeration unit 22, the methane fermentation zone 42, and the hydrogen supply area 91, returning to the biogas storage unit 70 (second compartment 72). As a result, CO2 remaining in the biogas BG in the second compartment 72 is converted to methane, increasing the methane concentration in the biogas BG. The biogas BG in the second compartment 72, in which the methane concentration has been increased, passes through the vent hole in the second partition plate 62 and is introduced into the third compartment 73, which is located downstream in the direction of biomass flow.

[0055] Then, a portion of the biogas BG introduced into the third compartment 73 with its methane concentration gradually increased is supplied to the aeration unit 22 via the third return pipe 81c. In this way, a portion of the biogas BG in the third compartment 73 is circulated by the third circulation circuit 80c from the third compartment 73 through the third return pipe 81c, the aeration unit 22, the methane fermentation zone 42, and the hydrogen non-supply area 92 back into the biogas storage unit 70 (third compartment 73). In this way, by circulating the biogas BG through the hydrogen non-supply area 92 to which hydrogen is not supplied from the aeration unit 22, the hydrogen in the biogas BG is consumed by hydrogen-assimilating methanogens, and the methane concentration in the biogas BG is increased.

[0056] In the first circulation circuit 80a, the entire amount of biogas BG returned from the first return pipe 81a through the aeration section 22 into the fermenter 2 may be returned to the first compartment chamber 71 in the biogas storage section 70, but it is also possible for only a portion of the biogas BG to return to the first compartment chamber 71, and not necessarily all of the biogas BG. In this case, the remaining biogas BG that does not return to the first compartment chamber 71 is introduced into the second compartment chamber 72 and / or the third compartment chamber 73 in the biogas storage section 70.

[0057] In the second circulation circuit 80b, the entire amount of biogas BG returned from the second return pipe 81b through the aeration section 22 to the fermenter 2 may be returned to the second compartment chamber 72 in the biogas storage section 70, but it is also possible for only a portion of the biogas BG to return to the second compartment chamber 72, and not necessarily all of the biogas BG. In this case, the remaining biogas BG that does not return to the second compartment chamber 72 is introduced into the first compartment chamber 71 and / or the third compartment chamber 73 in the biogas storage section 70.

[0058] In the third circulation circuit 80c, the entire amount of biogas BG returned from the third return pipe 81c through the aeration section 22 to the fermenter 2 may be returned to the third compartment 73 in the biogas storage section 70, but it is also possible for only a portion of the biogas BG to return to the third compartment 73, and not necessarily all of the biogas BG. In this case, the remaining biogas BG that does not return to the third compartment 73 is introduced into the first compartment 71 and / or the second compartment 72 in the biogas storage section 70.

[0059] The biogas BG in the biogas storage section 70 is recovered by the biogas recovery section 5 through the gas vent port 24 from the third compartment 73, for example, as shown by the solid line in Fig. 4, and is then effectively utilized. Note that the recovery mode of the biogas BG by the biogas recovery section 5 is not limited to the example shown by the solid line in Fig. 4, and may be recovered by the biogas recovery section 5 from the first compartment 71 or the second compartment 72 through the gas vent port 24, as shown by the two-dot chain line in Fig. 4.

[0060] In this way, biogas BG is sequentially introduced into multiple compartments (first compartment 71 to third compartment 73) from upstream to downstream in the biomass flow direction, and a portion of the biogas BG in each compartment 71 to 73 is returned to and circulated in the fermenter 2 via the circulation circuits 80a, 80b, and 80c through the aeration section 22, thereby ultimately enabling the methane concentration in the biogas BG to be gradually increased.

[0061] Fifth Embodiment Fig. 5 is a schematic diagram showing the overall configuration of a biomass treatment apparatus 1E of a fifth embodiment. Fig. 5(a) is a diagram showing a state in which a hydrogen-containing gas is diffused into a position between the upstream and downstream in the direction of biomass flow inside the fermenter 2. Fig. 5(b) is a diagram showing a state in which a hydrogen-containing gas is diffused so that hydrogen supply areas 91 and hydrogen non-supply areas 92 are alternately formed in the direction of biomass flow inside the fermenter 2. Fig. 5(c) is a diagram showing a state in which a hydrogen-containing gas is diffused so that hydrogen non-supply areas 92 and hydrogen supply areas 91 are alternately formed in the direction of biomass flow inside the fermenter 2.

[0062] 5(a) to 5(c), in the biomass processing apparatus 1E of the fifth embodiment, the aeration unit 22 is disposed so as to extend in the longitudinal direction (biomass flow direction) and circumferential direction of the trunk portion 10 so as to be able to diffuse gas to any desired part throughout the interior of the fermenter 2. In the gas supply unit 4, for example, aeration pipes and the like are disposed in the aeration unit 22, and the aeration pipes and the like are connected by piping, with control valves and the like disposed at key points in the piping so that the position at which the hydrogen-containing gas is diffused within the fermenter 2 can be freely changed.

[0063] In the biomass processing apparatus 1E of the fifth embodiment, the position at which the hydrogen-containing gas is diffused by the gas supply unit 4 into the fermenter 2 can be freely changed. As a result, for example, as shown in Fig. 5(a), the hydrogen-containing gas can be diffused into a position between the upstream and downstream portions of the fermenter 2 in the direction of biomass flow, as shown in Fig. 5(b), the hydrogen-containing gas can be diffused so that hydrogen-supply areas 91 and hydrogen-non-supply areas 92 are alternately formed in the direction of biomass flow inside the fermenter 2, or as shown in Fig. 5(c), the hydrogen-containing gas can be diffused so that hydrogen-non-supply areas 92 and hydrogen-supply areas 91 are alternately formed in the direction of biomass flow inside the fermenter 2. This makes it possible to appropriately adjust the supply of hydrogen-containing gas depending on the progress of the hydrolysis reaction, acid production reaction, and methane production reaction.

[0064] Sixth Embodiment Fig. 6 is a schematic diagram showing the overall configuration of a biomass processing apparatus 1F of the sixth embodiment. As shown in Fig. 6, in the biomass processing apparatus 1F of the sixth embodiment, a partition wall 95 is disposed in the fermenter 2 to separate the portion of the fermenter 2 that contains the fermentation liquor FL into an upstream side and a downstream side in the flow direction so that the fermentation liquor FL can flow in the biomass flow direction. The region between one side end surface 11 and the partition wall 95 is the acid fermentation zone 41, and the region between the partition wall 95 and the other side end surface 12 is the methane fermentation zone 42.

[0065] The partition section 95 is not particularly limited as long as it can separate the portion of the fermentation tank 2 in which the fermentation liquid FL is stored into an upstream side and a downstream side in the flow direction so that the fermentation liquid FL can flow in the biomass flow direction. Examples of the partition section 95 include a partition plate provided with a required flow opening so as to restrict but not block the movement of the fermentation liquid FL from the acid fermentation zone 41 to the methane fermentation zone 42, and a partition plate set at a height lower than the liquid level of the fermentation liquid FL so that it can overflow from the acid fermentation zone 41 to the methane fermentation zone 42.

[0066] In the biomass treatment apparatus 1F of the sixth embodiment, an acid production reaction takes place in an acid fermentation zone 41 located upstream in the biomass flow direction and separated by a partition wall 95 in the portion where the fermentation liquor FL is accommodated. Meanwhile, a methane production reaction takes place in a methane fermentation zone 42 located downstream in the biomass flow direction and separated by the partition wall 95. In this case, the acid production reaction and the methane production reaction take place in conjunction with each other under conditions where a constant amount of fermentation liquor FL moves from the upstream side to the downstream side in the biomass flow direction. Then, a hydrogen-containing gas is supplied by the gas supply unit 4 downstream of the partition wall 95 where the methane production reaction takes place. This allows hydrogen-assimilating methanogens to produce methane through a CO2-reducing methane production reaction using hydrogen derived from the hydrogen-containing gas supplied by the gas supply unit 4 and CO2, which is inevitably produced by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria, as substrates. At this time, the partition wall 95 prevents hydrogen derived from the hydrogen-containing gas supplied downstream of the partition wall 95 from moving upstream of the partition wall 95, thereby suppressing product inhibition in the acid fermentation zone 41. Therefore, the efficiency of methane production can be improved.

[0067] In Figure 6, an example is shown in which the part of the fermentation tank 2 in which the fermentation liquid FL is stored is divided into two compartments by one partition 95, but it may also be divided into three or more compartments by providing two or more partitions 95.

[0068] Seventh Embodiment Figure 7 is a schematic diagram showing the overall configuration of a biomass processing apparatus 1G of the seventh embodiment. In the biomass processing apparatus 1G of the seventh embodiment shown in Figure 7, a partition 95 is arranged so as to be movable in the longitudinal direction of the body 10 (biomass flow direction), and a slide mechanism 96 is arranged to move the partition 95 along the biomass flow direction, so that the relative position of the partition 95 in the biomass flow direction with respect to the fermenter 2 can be adjusted by the slide mechanism 96. The rest of the configuration is the same as that of the biomass processing apparatus 1F of the sixth embodiment.

[0069] It goes without saying that the biomass processing apparatus 1G of the seventh embodiment can achieve the same effects as the biomass processing apparatus 1F of the sixth embodiment. Furthermore, according to the biomass processing apparatus 1G of the seventh embodiment, in the case where an acid production reaction takes place on the upstream side of the biomass flow direction separated by the partition wall 95 in the portion where the fermentation liquid FL is accommodated, while a methane production reaction takes place on the downstream side of the biomass flow direction separated by the partition wall 95, by adjusting the position of the partition wall 95 in the biomass flow direction with the slide mechanism 96, the ratio of the acid production reaction on the upstream side of the partition wall 95 to the methane production reaction on the downstream side of the partition wall 95 can be easily adjusted.

[0070] 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.

[0071] (Another embodiment 1) Figure 8 is a diagram showing the state of diffusion of hydrogen-containing gas in the methane fermentation zone 42 in the biomass processing apparatus 1B of the second embodiment. Figure 8(a) is a diagram showing a state in which a relatively large amount of hydrogen-containing gas is diffused in the area between the upstream and downstream parts of the biomass flow direction in the methane fermentation zone 42. Figure 8(b) is a diagram showing a state in which the amount of hydrogen-containing gas diffused is gradually reduced as the biomass flows from the upstream part to the downstream part in the biomass flow direction in the methane fermentation zone 42. Figure 8(c) is a diagram showing a state in which hydrogen-containing gas is diffused so that hydrogen supply areas 91 and hydrogen non-supply areas 92 alternate in the biomass flow direction in the methane fermentation zone 42.

[0072] In the gas supply section 4 shown in Figures 8(a) to (c), for example, a diffuser pipe or the like is arranged in the aeration section 22, and the aeration pipe or the like is connected by piping, and control valves or the like are provided at key points in the piping so that the position and amount of diffusion of the hydrogen-containing gas into the methane fermentation zone 42 can be freely changed.

[0073] 8(a) to 8(c), it is possible to freely change the position and amount of hydrogen-containing gas diffused into the methane fermentation zone 42. As a result, for example, as shown in Fig. 8(a), it is possible to diffuse a relatively large amount of hydrogen-containing gas into the area between the upstream and downstream portions of the methane fermentation zone 42 in the direction of biomass flow, or as shown in Fig. 8(b), it is possible to gradually decrease the amount of hydrogen-containing gas diffused from the upstream portion to the downstream portion of the methane fermentation zone 42 in the direction of biomass flow, or as shown in Fig. 8(c), it is possible to diffuse hydrogen-containing gas so that hydrogen supply areas 91 and hydrogen non-supply areas 92 are alternately formed in the direction of biomass flow in the methane fermentation zone 42.

[0074] (Alternative embodiment 2) 4, an example has been shown in which the biogas BG inside the first compartment chamber 71, the second compartment chamber 72, and the third compartment chamber 73 is returned to essentially the same compartment chambers (the first compartment chamber 71, the second compartment chamber 72, and the third compartment chamber 73) via the first circulation circuit 80a, the second circulation circuit 80b, and the third circulation circuit 80c, but the present invention is not limited to this. For example, by changing the return position of the biogas BG to the aeration unit 22 by the first return pipe 81a in the first circulation circuit 80a, the biogas BG may be introduced from the first compartment chamber 71 through the first return pipe 81a, the aeration unit 22, and the fermentation liquid FL into the second compartment chamber 72 or the third compartment chamber 73 in the biogas storage unit 70. Furthermore, by changing the return position of the biogas BG to the aeration unit 22 by the second return pipe 81b in the second circulation circuit 80b, the biogas BG may be introduced from the second compartment 72 through the second return pipe 81b, the aeration unit 22, and the fermentation liquid FL into the first compartment 71 or the third compartment 73 in the biogas storage unit 70. Furthermore, by changing the return position of the biogas BG to the aeration unit 22 by the third return pipe 81c in the third circulation circuit 80c, the biogas BG may be introduced from the third compartment 73 through the third return pipe 81c, the aeration unit 22, and the fermentation liquid FL into the first compartment 71 or the second compartment 72 in the biogas storage unit 70.

[0075] (Alternative embodiment 3) In the above embodiment, the present invention is applied to a horizontal plug flow biomass treatment device, but the present invention is not limited to this and can also be applied to a vertical plug flow biomass treatment device. In this case, a fermenter corresponding to the fermenter 2 in the above embodiment has, for example, a vertically elongated cylindrical body with a vertical axis, an upper end face that closes the upper end of the body, and a lower end face that closes the lower end of the body, and is configured to ferment biomass while flowing from a biomass supply port 17 provided in the upper end face toward a digestive fluid discharge port 18 provided in the lower end face. Note that if the organic waste introduced into the fermenter is pushed out from the digestive fluid discharge port 18 by gravity, the pressure-feeding unit 15 can be omitted from the biomass supply unit 3.

[0076] In the above embodiment, a configuration including a horizontally long cylindrical plug flow type fermenter and a vertically long cylindrical plug flow type fermenter has been shown, but this is not limited to this, and a configuration including a cylindrical plug flow type fermenter with approximately the same aspect ratio is also possible. [Industrial Applicability]

[0077] 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]

[0078] 1A~1G Biomass processing equipment 2 Fermentation tanks 4 Gas supply section 6 Reuse equipment 41 Acid Fermentation Zone 42 Methane Fermentation Zone 50 circulation circuit 70 Biogas storage section 71~73 compartments 80a~80c circulation circuit 91 Hydrogen Supply Area 92 Hydrogen non-supply area 95 Bulkhead

Claims

1. A biomass treatment device that ferments biomass to produce biogas, a plug flow type fermenter that stores a fermentation liquid obtained by fermenting the biomass while flowing; a gas supply unit that supplies a hydrogen-containing gas to the fermentation liquid; A biomass treatment device comprising:

2. The fermenter has an acid fermentation zone and a methane fermentation zone, The biomass treatment apparatus according to claim 1 , wherein the gas supply unit supplies the hydrogen-containing gas to the methane fermentation zone.

3. The biomass treatment apparatus according to claim 1 , wherein the fermenter has a hydrogen supply area to which the hydrogen-containing gas is supplied and a hydrogen non-supply area to which the hydrogen-containing gas is not supplied.

4. The biomass treatment device according to claim 1 , wherein a partition wall is disposed in the fermenter tank to separate the portion containing the fermentation liquid into an upstream side and a downstream side in the flow direction so that the fermentation liquid can flow in the flow direction of the biomass.

5. The biomass treatment apparatus according to claim 4, wherein the position of the partition wall in the flow direction of the biomass is adjustable.

6. The fermenter has a biogas storage section that stores the biogas, The biomass treatment device according to any one of claims 1 to 5, further comprising a circulation circuit for returning a portion of the biogas in the biogas storage unit to the gas supply unit and circulating the returned portion.

7. The biomass treatment apparatus according to claim 6 , wherein the biogas storage unit includes a plurality of compartments that are arranged in communication with each other along the direction of flow of the biomass.

8. The biomass treatment device according to any one of claims 1 to 5, further comprising a recycling device that filters the fermentation liquid, discharges the filtrate, and returns the filtered material to the fermenter.

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