Organic waste treatment system, biogas production device, and organic waste treatment method

Abstract

To provide an organic waste treatment system, a biogas production device, and an organic waste treatment method capable of maintaining an amount of microorganisms in a methane fermentation tank and efficiently producing biogas.SOLUTION: There is provided an organic waste treatment system 1 including: a decomposition device 10 for pressurizing and decomposing organic waste A to obtain a first fluid B containing a nitrogen component C; a recovery device 20 for recovering the nitrogen component C contained in the first fluid B to obtain a second fluid D; a separator 30 for separating the second fluid D into gas E and liquid F; and a biogas production device 40 for producing biogas containing methane gas from a culture solution containing the liquid F and anaerobic microorganisms.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an organic waste treatment system, a biogas production apparatus, and a method for treating organic waste. [Background technology]

[0002] Organic waste such as sewage sludge is generated in large quantities and is attracting attention as one of the domestic biomass materials accumulated in treatment plants. There is a demand for recovering and utilizing the energy contained in such organic waste. One example of a method for effectively utilizing the organic matter contained in organic waste is the production of biogas containing methane gas by methane fermentation.

[0003] For example, Patent Document 1 proposes a method for treating organic waste in which a part of the organic waste is solubilized in water, the organic waste solubilized in water is filtered, and the filtered liquid component is subjected to methane fermentation. According to the technology of Patent Document 1, water-soluble components are recovered from the organic waste by filter filtration, and the efficiency of methane fermentation is improved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-6880 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology of Patent Document 1, the filtered liquid component (culture solution) has a lower organic matter concentration than the raw organic waste, and the growth of microorganisms in the culture solution cannot keep up with the amount of wastewater, resulting in a low amount of microorganisms. This raises concerns about a decrease in biogas production efficiency.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide an organic waste treatment system, a biogas production apparatus, and an organic waste treatment method that can maintain the amount of microorganisms in a culture solution and efficiently produce biogas. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following aspects. [1] A decomposition device for decomposing organic waste under pressure to obtain a first fluid containing a nitrogen component; a recovery device for recovering the nitrogen component contained in the first fluid to obtain a second fluid; a separation device for separating the second fluid into a gas and a liquid; and a biogas production device that produces biogas containing methane gas from a culture solution containing the liquid and anaerobic microorganisms. death, The pressure of the second fluid in the separation device is 1 MPa or more. An organic waste treatment system. [2] The biogas production apparatus includes a culture tank that accommodates the culture solution, and a filter that filters the culture solution in the culture tank; The organic waste treatment system according to [1], further comprising a discharge pipe for discharging the filtrate produced in the filter. [3] A biogas production apparatus that produces biogas containing methane gas from a liquid obtained by pressurizing organic waste, A culture tank containing a culture solution containing the liquid and anaerobic microorganisms; A filter for filtering the culture solution; A discharge pipe for discharging the filtrate generated in the filter; A separator connected to the biogas production apparatus; a recovery device connected to the separation device for obtaining a second fluid; Have death, The separation device separates the second fluid into a gas and a liquid, The recovery device recovers the nitrogen component contained in a first fluid containing a nitrogen component obtained by pressurizing and decomposing organic waste, The pressure of the second fluid in the separation device is 1 MPa or more. A biogas production device.

[0008] [4] A decomposition step of decomposing the organic waste under pressure to obtain a first fluid containing a nitrogen component; a recovery step of recovering the nitrogen component contained in the first fluid to obtain a second fluid; a separation step of separating the second fluid into a gas and a liquid; and a biogas production process for producing a biogas containing methane gas from a culture solution containing the liquid and anaerobic microorganisms. death, In the separation step, the pressure of the second fluid is 1 MPa or more. A method for treating organic waste. Effect of the Invention

[0009] According to the organic waste treatment system, biogas production apparatus, and organic waste treatment method of the present invention, the amount of microorganisms in the methane fermentation tank can be maintained, and biogas can be produced efficiently. [Brief description of the drawings]

[0010] [Figure 1] 1 is a flow diagram illustrating a schematic configuration of an organic waste treatment system according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a schematic diagram of a biogas production apparatus according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Organic waste treatment system> The organic waste treatment system of the present invention comprises a decomposition device, a recovery device, a separation device, and a biogas production device. Hereinafter, an embodiment of an organic waste treatment system of the present invention will be described with reference to the drawings.

[0012] As shown in Fig. 1, an organic waste treatment system 1 of this embodiment has a decomposition apparatus 10, a recovery apparatus 20, a separation apparatus 30, and a biogas production apparatus 40. The decomposition apparatus 10 and the recovery apparatus 20 are connected by piping. The recovery apparatus 20 and the separation apparatus 30 are connected by piping. The separation apparatus 30 and the biogas production apparatus 40 are connected by piping. The arrows in the figure indicate the direction of movement of fluids such as raw materials and products.

[0013] The decomposition device 10 is a device that decomposes organic waste by pressurizing it to obtain a fluid containing a nitrogen component. The decomposition device 10 may be, for example, a pressure-resistant vessel equipped with a pressurizing device. The pressurizing device may be any device capable of pressurizing the inside of the decomposition device 10, and examples thereof include a high-pressure pump and a pressure regulating valve. The pressure vessel may be made of, for example, a metal such as stainless steel or a nickel alloy.

[0014] The decomposition device 10 may have a heater. The heater may be any heater capable of heating the inside of the decomposition apparatus 10, and examples of the heater include a steam heater that passes high-temperature steam through it, and a gas boiler.

[0015] The recovery device 20 is a device that separates the nitrogen component contained in the fluid. The recovery device 20 may be, for example, an adsorption tower equipped with an adsorbent capable of adsorbing the nitrogen component C contained in the first fluid B.

[0016] The separation device 30 is a device that separates a gas-liquid mixed fluid into a gas and a liquid. An example of the separation device 30 is a gas-liquid separator such as a condenser equipped with a heat exchanger.

[0017] The biogas production device 40 is a device that produces biogas containing methane gas from a culture solution containing anaerobic microorganisms and a liquid containing carbon components obtained from organic waste A. An example of the biogas production device 40 is a methane fermentation tank that is equipped with a culture tank that contains the culture solution, a pressure reducing valve, and a discharge pipe.

[0018] The biogas production apparatus 40 preferably has a filter that filters the culture liquid in the culture tank. The filter may be, for example, a filter having a pore size that does not allow anaerobic microorganisms to pass through. The pore size of the filter may be any size that does not allow anaerobic microorganisms to pass through, and is preferably, for example, 5 μm or less, and more preferably 1 μm or less. The lower limit of the pore size of the filter is preferably, for example, 0.1 μm. When the pore size of the filter is equal to or greater than the above lower limit, water contained in the culture solution can be easily discharged. In addition, when the pore size of the filter is equal to or greater than the above lower limit, the internal pressure of the culture tank of the biogas production apparatus 40 can be prevented from becoming too high.

[0019] The culture tank may be, for example, a pressure-resistant vessel made of metal such as stainless steel or nickel alloy. The pressure reducing valve may be, for example, a conventionally known on-off valve such as a pressure adjusting valve. The exhaust pipe may be, for example, a pipe made of metal or resin.

[0020] <How to dispose of organic waste> The organic waste treatment method of the present invention includes a decomposition step, a recovery step, a separation step, and a biogas production step. An organic waste treatment method using an organic waste treatment system 1 will be described with reference to FIG.

[0021] First, organic waste A is supplied to the decomposition device 10. Examples of the organic waste A include ammonia-containing digestive fluid, food waste, livestock waste, concentrated sewage sludge and digested sludge, organic sludge, etc. The organic waste A contains nitrogen components in addition to carbon components.

[0022] The decomposition step is a step in which organic waste A is decomposed under pressure to obtain a first fluid B containing a nitrogen component C. The internal pressure of the decomposition apparatus 10 in the decomposition step should be at least higher than atmospheric pressure (0.1 MPa), and is preferably 5 MPa or higher, more preferably 10 MPa or higher, and may be 22 MPa (critical pressure of water) or higher, for example. When the internal pressure of the decomposition apparatus 10 in the decomposition step is equal to or higher than the lower limit, the organic waste A can be decomposed into carbon components and nitrogen components C. The upper limit of the internal pressure of the decomposition apparatus 10 in the decomposition step is not particularly limited, but is, for example, equal to or lower than 30 MPa.

[0023] The internal pressure of the cracking apparatus 10 can be adjusted, for example, by a high-pressure pump and a pressure regulating valve.

[0024] In the decomposition step, the internal pressure of the decomposition device 10 does not need to be high (for example, 5 MPa). In that case, it is preferable to use a chemical capable of decomposing the organic waste A or to heat the decomposition device 10. Examples of chemicals capable of decomposing organic waste A include sodium hydroxide and hydrogen peroxide.

[0025] When the decomposition apparatus 10 is heated, the internal temperature of the decomposition apparatus 10 is, for example, preferably 60° C. or higher, more preferably 100° C. or higher, and may be 374° C. (the critical temperature of water) or higher. When the internal temperature of the decomposition apparatus 10 is equal to or higher than the lower limit, the solubility of the organic waste A increases, and the decomposition of the organic waste A can be further promoted. By setting the internal temperature of the decomposition apparatus 10 to 374°C or higher and the internal pressure of the decomposition apparatus 10 to 5 MPa or higher, the inside of the decomposition apparatus 10 can be placed under subcritical or supercritical water conditions. By setting the inside of the decomposition apparatus 10 under subcritical or supercritical water conditions, the organic waste A can be completely decomposed, which is more preferable.

[0026] The solid content that remains undecomposed in the decomposition step can be discharged to the outside of the decomposition device 10 using, for example, an extrusion pump.

[0027] The recovery step is a step of recovering the nitrogen component C contained in the first fluid B to obtain a second fluid D. The first fluid B is obtained from a decomposition process and is therefore in a high pressure liquid or gas state. The pressure of the first fluid B should be at least higher than atmospheric pressure (0.1 MPa), and is preferably 5 MPa or higher, and more preferably 10 MPa or higher. When the pressure of the first fluid B is equal to or higher than the lower limit, the pressure of the culture solution in the biogas production step described below can be increased. This allows the culture solution to be filtered more smoothly, and the concentration of microorganisms in the culture solution can be maintained. As a result, biogas can be produced more efficiently. The upper limit of the pressure of the first fluid B is not particularly limited, but is set to, for example, 30 MPa or less.

[0028] In the recovery step, the nitrogen component C contained in the first fluid B is removed and recovered. Examples of the nitrogen component C include nitrogen and ammonia. These nitrogen components C can be used as a hydrogen energy transport medium (energy carrier) or a fuel (energy source). Therefore, it is preferable to recover the nitrogen component C because energy can be effectively utilized. In addition, by recovering the nitrogen component C, it is possible to suppress, for example, inhibition of methane fermentation caused by high concentrations of ammonia in the biogas production process described below, and therefore it is possible to produce biogas more efficiently.

[0029] A method for removing the nitrogen component C includes, for example, supplying the first fluid B to an adsorption tower equipped with an adsorbent capable of adsorbing the nitrogen component C, contacting the first fluid B with the adsorbent, adsorbing the nitrogen component C contained in the first fluid B onto the adsorbent, and then desorbing the nitrogen component C from the adsorbent. The adsorption and desorption of the nitrogen component C can be controlled by adjusting the internal pressure and internal temperature of the adsorption tower. Examples of the adsorbent capable of adsorbing the nitrogen component C include known adsorbents such as zeolite and magnesium phosphate.

[0030] The separation step is a step of separating the second fluid D into a gas E and a liquid F. The second fluid D has the nitrogen component C removed, and therefore contains a carbon component and moisture. The pressure of the second fluid D is, for example, preferably 1 MPa or more, more preferably 5 MPa or more. When the pressure of the second fluid D is equal to or more than the above lower limit, the pressure of the culture solution in the biogas production process described below can be increased. This allows the culture solution to be filtered more smoothly, and the concentration of microorganisms in the culture solution can be maintained. As a result, biogas can be produced more efficiently. The upper limit of the pressure of the second fluid D is not particularly limited, but is set to, for example, 30 MPa or less.

[0031] The gas E may be, for example, an exhaust gas containing water vapor and carbon dioxide generated in the decomposition step. The gas E may also contain oxygen, sulfur dioxide, and the like. The liquid F may be, for example, a treatment liquid containing water produced in the decomposition step or a low molecular weight organic acid such as acetic acid.

[0032] Methods for separating the second fluid D into gas E and liquid F include, for example, a method in which the water evaporated by heating is condensed by cooling, and a method in which the treatment liquid in a subcritical state is vaporized by reducing the pressure. The separation of the gas E and the liquid F in the separation process can be controlled by adjusting the internal pressure and internal temperature of the separation device 30.

[0033] The gas E is discharged to the outside of the separation device 30 as exhaust gas. The liquid F is supplied to the biogas production apparatus 40 as a treated liquid.

[0034] The biogas production process is a process for producing biogas containing methane gas from a culture liquid containing liquid F containing carbon components obtained from organic waste A and anaerobic microorganisms. In the biogas production process, organic matter contained in the treatment liquid (liquid F) is decomposed by the anaerobic microorganisms. In the biogas production process, carbon dioxide may be reduced by the anaerobic microorganisms. Biogas G containing methane gas is generated by the decomposition of the organic matter contained in the treatment liquid and the reduction of carbon dioxide. The biogas G is supplied to the outside of the biogas production apparatus 40 and can be effectively utilized as an energy source.

[0035] Examples of anaerobic microorganisms include methanogens such as Methanosarcina archaea and Methanothermobacter archaea. Methanosarcina barkeri is preferred as the anaerobic microorganism because it can produce biogas more efficiently by reducing carbon dioxide.

[0036] When the biogas production apparatus 40 has a filter that filters the culture solution containing the liquid F and anaerobic microorganisms, the water and unnecessary water-soluble components contained in the culture solution can be discharged as filtrate to the outside through a discharge pipe connected to the culture tank. Therefore, the concentration of anaerobic microorganisms in the culture solution can be kept at a certain level or higher, and the amount of microorganisms can be maintained. As a result, biogas can be produced efficiently. The concentration of microorganisms in the culture medium is 1 x 10 2 ~1×10 9 Cells / mL is preferred, 1×10 4 ~1×10 8 Cells / mL is more preferable. When the concentration of the microorganisms in the culture solution is equal to or higher than the lower limit, biogas can be produced more efficiently. When the concentration of the microorganisms in the culture solution is equal to or lower than the upper limit, the amount of excess microorganisms I can be reduced. The concentration of microorganisms in the culture medium can be determined, for example, by observation under a microscope or by measurement using an automatic cell counter.

[0037] Since the liquid F is obtained through a decomposition process, it is a high-pressure liquid. Therefore, the culture solution containing the liquid F is in a pressurized state, and the culture solution can be filtered smoothly. In addition, since the liquid F is supplied at high pressure, there is no need to pressurize the inside of the culture tank of the biogas production device 40 again. Therefore, there is no need to supply energy to pressurize the inside of the culture tank of the biogas production device 40, and energy savings can be achieved. The internal pressure of the culture tank should be at least higher than atmospheric pressure (0.1 MPa), and is preferably, for example, 1 MPa or higher, and more preferably 5 MPa or higher. The upper limit of the internal pressure of the culture tank is not particularly limited, but is set to, for example, 30 MPa.

[0038] In the biogas production process, moisture and water-soluble components not required for biogas production are discharged as wastewater H to the outside via a discharge pipe connected to the culture tank of the biogas production apparatus 40. Anaerobic microorganisms that become excessive in producing biogas are discharged to the outside as surplus microorganisms I through a discharge pipe connected to the culture tank of the biogas production apparatus 40. The surplus microorganisms I may be supplied to the decomposition apparatus 10 and subjected to decomposition treatment together with the organic waste A.

[0039] According to the organic waste treatment system 1 of this embodiment, the nitrogen component C obtained by the pressure treatment of the organic waste A can be effectively used as an energy carrier or energy source. According to the organic waste treatment system 1, biogas can be produced from the liquid F obtained by the pressurization treatment. According to the organic waste treatment system 1, it is possible to maintain a high concentration of anaerobic microorganisms inside the biogas production device 40. Therefore, it is possible to efficiently produce biogas. According to the organic waste treatment system 1, the nitrogen component C can be recovered, and therefore inhibition of methane fermentation caused by high concentration ammonia can be suppressed, thereby enabling efficient production of biogas. According to the organic waste treatment system 1, the liquid F that has been sterilized by pressure treatment is used, so that it is possible to stably culture anaerobic microorganisms without contamination with unwanted bacteria. According to the organic waste treatment system 1, oxygen is consumed during the pressurization treatment, so that an anaerobic environment is easily maintained. The organic waste treatment system 1 can provide an environment suitable for cultivating microorganisms that grow in special environments such as high temperature and high pressure environments.

[0040] <Biogas production equipment> The biogas production apparatus of the present invention is an apparatus that produces biogas containing methane gas from a liquid obtained by pressurizing organic waste. The biogas production apparatus of the present invention has a culture tank that contains a culture solution containing a liquid obtained by pressurizing organic waste and anaerobic microorganisms, a filter that filters the culture solution, and a discharge pipe that discharges the filtrate produced in the filter. Hereinafter, one embodiment of a biogas production apparatus of the present invention will be described with reference to the drawings.

[0041] As shown in Fig. 2, the biogas production apparatus 50 of this embodiment includes a culture tank 52, a water tank 53, a filter 54, a pressure reducing valve 56, a pressure reducing valve 58, a pipe L1, a pipe L2, a discharge pipe L3, and a discharge pipe L4. The filter 54 is installed inside the culture tank 52. A water tank 53 is provided outside the culture tank 52. The pipes L1, L2, and the discharge pipe L3 are each connected to the culture tank 52. The discharge pipe L4 is connected to the water tank 53. The pipe L2 is provided with a pressure reducing valve 56. The discharge pipe L3 is provided with a pressure reducing valve 58.

[0042] An example of the biogas production apparatus 50 is a methane fermentation tank equipped with a pressure-resistant vessel, a pressure reducing valve, and a discharge pipe, similar to the biogas production apparatus 40 of the organic waste treatment system 1 described above. Biogas production system 50 may be the same as biogas production system 40 or may be different.

[0043] The culture tank 52 may be, for example, a pressure-resistant vessel capable of accommodating anaerobic microorganisms. The pressure-resistant vessel may be, for example, a pressure-resistant vessel made of metal such as stainless steel or nickel alloy.

[0044] The water tank 53 may be, for example, a pressure-resistant container capable of containing water. The water tank 53 may be, for example, a pressure-resistant container made of glass or transparent resin.

[0045] The filter 54 may be, for example, a filter having a pore size large enough to prevent anaerobic microorganisms from passing through. The pore size of the filter may be any size that does not allow anaerobic microorganisms to pass through, and is preferably, for example, 5 μm or less, more preferably 1 μm or less. The lower limit of the pore size of the filter is preferably, for example, 0.1 μm. When the pore size of the filter is equal to or greater than the above lower limit, water contained in the culture solution can be easily discharged. In addition, when the pore size of the filter is equal to or greater than the above lower limit, the internal pressure of the culture tank 52 of the biogas production apparatus 50 can be prevented from becoming too high.

[0046] The pressure reducing valve 56 may be, for example, a conventionally known on-off valve such as a pressure adjusting valve. An example of the pressure reducing valve 58 is an on-off valve similar to the pressure reducing valve 56 .

[0047] The pipes L1 and L2 are, for example, pipes made of metal or resin. The discharge pipes L3 and L4 may be, for example, metal or resin pipes similar to the pipes L1 and L2.

[0048] Next, a method for producing biogas using the biogas production apparatus 50 of this embodiment will be described with reference to FIG. In FIG. 2, the symbols F, G, H, and I are the same as the liquid F, biogas G, wastewater H, and excess microorganisms I described in FIG.

[0049] First, the liquid F is supplied to the culture tank 52 via the pipe L1. The culture tank 52 contains a culture solution containing anaerobic microorganisms. Examples of anaerobic microorganisms include methanogens such as Methanosarcina archaea and Methanothermobacter archaea. Methanosarcina barkeri is preferred as the anaerobic microorganism because it can produce biogas more efficiently by reducing carbon dioxide.

[0050] Liquid F contains water and low molecular weight organic acids such as acetic acid. By supplying liquid F to the culture tank 52, anaerobic microorganisms decompose the organic matter contained in liquid F and reduce carbon dioxide, generating biogas G containing methane gas. The biogas G is supplied to the outside of the biogas production apparatus 50 via the pipe L2 and can be effectively used as an energy source.

[0051] The culture liquid containing the liquid F and anaerobic microorganisms is filtered by the filter 54 installed inside the culture tank 52. At this time, the water content and unnecessary water-soluble components contained in the culture liquid pass through the filter 54 and are stored in the water tank 53. The water content and unnecessary water-soluble components stored in the water tank 53 are discharged to the outside via the discharge pipe L4 as wastewater (filtrate generated by the filter 54) H. Therefore, the concentration of anaerobic microorganisms contained inside the culture tank 52 of the biogas production apparatus 50 can be maintained at a certain level or higher, and the amount of microorganisms can be maintained. As a result, biogas can be produced efficiently.

[0052] The concentration of microorganisms in the culture medium is 1 x 10 2 ~1×10 9 Cells / mL is preferred, 1×10 4 ~1×10 8 Cells / mL is more preferable. When the concentration of the microorganisms in the culture solution is equal to or higher than the lower limit, biogas can be produced more efficiently. When the concentration of the microorganisms in the culture solution is equal to or lower than the upper limit, the amount of excess microorganisms I can be reduced. The concentration of microorganisms in the culture medium can be determined, for example, by observation under a microscope or by measurement using an automatic cell counter. The concentration of the microorganisms in the culture liquid can be adjusted by the concentration of the microorganisms before mixing with the liquid F, the amount of the liquid F supplied to the culture tank 52, or a combination thereof.

[0053] Since the liquid F is obtained through the decomposition process, it is a high-pressure liquid. Therefore, the culture solution containing the liquid F is in a pressurized state, and the culture solution passes through the filter 54 in a pressurized state. Therefore, the culture solution passes through the filter 54 smoothly, and the efficiency of filtration can be improved. As a result, biogas can be produced efficiently. In addition, since the high-pressure liquid F is supplied, there is no need to pressurize the inside of the culture tank 52 again. Therefore, there is no need to supply energy for pressurizing the inside of the culture tank 52, and energy savings can be achieved. The internal pressure of the culture tank 52 should be at least higher than atmospheric pressure (0.1 MPa), and is preferably, for example, 1 MPa or higher, and more preferably 5 MPa or higher. The upper limit of the internal pressure of the culture tank 52 is not particularly limited, but is set to, for example, 30 MPa. The internal pressure of the culture tank 52 can be adjusted by opening and closing the pressure reducing valve 56 and the pressure reducing valve 58 .

[0054] Excess anaerobic microorganisms inside the culture tank 52 settle to the bottom of the culture tank 52. The anaerobic microorganisms that have settled to the bottom of the culture tank 52 are discharged as surplus microorganisms I to the outside of the biogas production apparatus 50 via the discharge pipe L3.

[0055] The organic waste treatment system, biogas production apparatus, and organic waste treatment method of the present invention have been described above, but the present invention is not limited to the above embodiments and can be modified as appropriate without departing from the spirit of the present invention. For example, in the biogas production apparatus 50, the filter 54 is installed inside the culture tank 52. However, in the biogas production apparatus, the filter may be installed outside the culture tank. [Explanation of symbols]

[0056] 1...organic waste treatment system, 10...decomposition device, 20...recovery device, 30...separation device, 40...biogas production device, 50...biogas production device, 52...culture tank, 53...water tank, 54...filter, 56, 58...pressure reducing valve, L1~L2...piping, L3~L4...discharge pipe

Claims

1. a decomposition device for decomposing the organic waste by pressurizing the organic waste to obtain a first fluid containing a nitrogen component; a recovery device for recovering the nitrogen component contained in the first fluid to obtain a second fluid; a separation device for separating the second fluid into a gas and a liquid; and a biogas production device that produces a biogas containing methane gas from a culture solution containing the liquid and anaerobic microorganisms, An organic waste treatment system, wherein the pressure of the second fluid in the separation device is 1 MPa or more.

2. The biogas production apparatus includes a culture tank that accommodates the culture liquid, and a filter that filters the culture liquid in the culture tank; The organic waste treatment system according to claim 1 , further comprising a discharge pipe for discharging the filtrate produced in the filter.

3. A biogas production apparatus that produces biogas containing methane gas from a liquid obtained by pressurizing organic waste, A culture tank containing a culture solution containing the liquid and anaerobic microorganisms; A filter for filtering the culture solution; A discharge pipe for discharging the filtrate generated in the filter; A separator connected to the biogas production apparatus; a recovery device connected to the separation device for obtaining a second fluid, The separation device separates the second fluid into a gas and a liquid, The recovery device recovers the nitrogen component contained in a first fluid containing a nitrogen component obtained by pressurizing and decomposing organic waste, A biogas production apparatus, wherein the pressure of the second fluid in the separation device is 1 MPa or more.

4. a decomposition step of decomposing the organic waste under pressure to obtain a first fluid containing a nitrogen component; a recovery step of recovering the nitrogen component contained in the first fluid to obtain a second fluid; a separation step of separating the second fluid into a gas and a liquid; and a biogas production process for producing a biogas containing methane gas from a culture solution containing the liquid and anaerobic microorganisms. A method for treating organic waste, wherein in the separation step, the pressure of the second fluid is 1 MPa or more.

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