KR20210039848A - Manufacturing of bio-methane for high purity bio-methane and method of producing bio-methane using the same - Google Patents

Abstract

The present invention relates to a biomethane production system for producing high purity biomethane. More particularly, the biomethane production system for producing high-purity biomethane comprises: an organic acid fermenter producing organic waste for use as a substrate for a methanation reaction and an intermediate metabolite of the organic waste; a methanation reactor producing biomethane by receiving the substrate of the methanation reaction from the organic acid fermenter, and culturing an anaerobic mixed microbial community to perform the methanation reaction; a hydrogen supply tank storing hydrogen gas, and injecting hydrogen into the methanation reactor in a continuous batch or semi-continuous manner; a monitoring unit monitoring the environmental conditions inside the organic acid fermenter and the environmental conditions inside the methanation reactor in real time; a control unit adjusting the environmental conditions measured by the monitoring unit according to a preset standard; a nutrient storage tank storing nutrients necessary for culturing anaerobic mixed microbial communities and supplying the same to the methanation reactor; and a biomethane storage tank recovering and storing biomethane gas from the methanation reactor.

Description

A biomethane production system for producing high-purity biomethane and a biomethane production method using the same {MANUFACTURING OF BIO-METHANE FOR HIGH PURITY BIO-METHANE AND METHOD OF PRODUCING BIO-METHANE USING THE SAME}

The present invention relates to the production of high-purity biomethane, and more particularly, a biomethane production system for producing high-purity biomethane by performing the biomethane production process in multiple steps by a methanation reaction using an anaerobic mixed microorganism community, and It relates to a biomethane production method using this.

The anaerobic fermentation process can be defined as a process in which biodegradable organic matters undergo a multi-stage biochemical reaction under conditions in which oxygen is not present, and finally decompose into biogas such as methane and carbon dioxide.

The biogas generated by the anaerobic fermentation process is mainly composed of about 25% to 50% of carbon dioxide, as impurities less than about 0.1% of air, about 7,000 ppm to 8,000 ppm of hydrogen sulfide, about 40 ppm of siloxane, etc. Contains ingredients. Such biogas can be used as natural gas, vehicle fuel, etc., and in order to utilize biogas, the quality of biogas is essential through gas purification and physical/chemical upgrading processes. It is necessary to improve.

Carbon dioxide, which is a representative impurity in the purification and upgrading of biogas, can generally be removed through methods such as pressure swing adsorption and water scrubbing.

The high-pressure adsorption method removes carbon dioxide by using the difference in the amount of gas adsorption of the adsorbent, and activated carbon, zeolite, silica gel, carbon molecular sieve, etc. can be used as an adsorbent, and other carbon dioxide is removed. Compared to the process, it has advantages such as a simple process, low energy requirements, and low maintenance costs, but has a disadvantage in that the methane recovery rate is low.

As another method, the aqueous solution absorption method removes carbon dioxide by using an absorbent that absorbs carbon dioxide, and an amine-based absorbent, ammonia, potassium carbonate, and an amino acid absorbent are used. The aqueous solution absorption method is the most commercialized method for removing carbon dioxide, but has a disadvantage in that the energy used for regeneration of the absorbent is excessive compared to other processes.

Korean Patent Application No. 10-2017-0101480

In order to solve the above problems, it is an object of the present invention to increase the efficiency of methane production and to produce high-purity methane at a high recovery rate. As a biological production system and production method, organic wastes and organic wastes are hydrolyzed and wheat fermented. Produces high-purity biomethane that can increase the content of methane gas in the biogas produced through the step of a biological methanation reaction using a methane-producing strain using intermediate metabolites generated in the process as a substrate. It is to provide a biomethane production system and a biomethane production method using the same.

The biomethane production system of the present invention for achieving the above object is an organic waste for use as a substrate for a methanation reaction, an organic acid fermentation tank for generating intermediate metabolites of the organic waste, and a substrate for a methanation reaction from the organic acid fermentation tank. A methanation reactor for producing biomethane by performing a methanation reaction by culturing an anaerobic mixed microbial community by receiving the supply, a hydrogen supply tank for storing hydrogen gas and injecting hydrogen into the methanation reactor in a continuous batch or semi-continuous manner, A monitoring unit that monitors the environmental conditions inside the organic acid fermentation tank and the environmental conditions inside the methanation reactor in real time, a control unit that adjusts the environmental conditions measured by the monitoring unit according to preset criteria, and cultivation of an anaerobic mixed microorganism community It characterized in that it comprises a nutrient storage tank for storing necessary nutrients and supplied to the methanation reactor, and a biomethane storage tank for recovering and storing biomethane gas from the methanation reactor.

In the biomethane production system of the present invention, the methanation reaction tank receives a methanation reaction substrate from the organic acid fermentation tank, receives hydrogen from the hydrogen supply tank, and performs a first methanation reaction using an anaerobic mixed microorganism community. A first methanation reaction tank for producing biogas containing methane and carbon dioxide, and a second methanation reaction using an anaerobic mixed microorganism community by receiving the biogas produced from the first methanation reaction tank, It is preferable to include a second methanation reactor for generating biomethane with an improved content.

The second methanation reactor is supplied with the biogas recovered from the first methanation reactor to improve the content of methane, and receives hydrogen from the hydrogen supply tank and operates under pressurized conditions to produce biomethane. It is desirable.

In the biomethane production system of the present invention, it is preferable that the first methanation reactor and the second methanation reactor included in the methanation reactor include a mechanical stirring device therein.

It is preferable that the head space above the first methanation reactor and the second methanation reactor is 20% or more and less than 50% based on 100% of the total volume of the total methanation reactor.

In the biomethane production system of the present invention, a substrate supply pipe that connects the methanation reactor and the organic acid fermentation tank and supplies a methanation reaction substrate from the organic acid fermentation tank to the methanation reactor, and is formed on one side of the methanation reactor. A hydrogen supply pipe for supplying hydrogen gas from a hydrogen supply tank, a nutrient supply pipe connected to the other side of the methanation reactor to supply nutrients necessary for culturing an anaerobic mixed microorganism community from the nutrient storage tank, and a methanation reaction in the methanation reactor A treated water discharge pipe for discharging the treated water used in the methanation reactor, and a biomethane recovery pipe for recovering biomethane produced by the methanation reaction in the methanation reactor and transferring it to the biomethane storage tank.

It is preferable that a check valve is installed on the substrate supply pipe to open and close the supply of the substrate for the methanation reaction supplied from the organic acid fermentation tank for control.

Another method for producing biomethane using the biomethane production system described above to achieve the above object includes (a) supplying a substrate for a methanation reaction through a substrate supply pipe from an organic acid fermentation tank to the first methanation reaction tank, and hydrogen Producing biogas containing methane and carbon dioxide by supplying hydrogen from a supply tank to perform a first methanation reaction using an anaerobic mixed microorganism community, and (b) in the second methanation reaction tank in step (a). It characterized in that it comprises the step of producing biomethane by supplying the produced biogas, supplying hydrogen from a hydrogen supply tank, and performing a secondary methanation reaction using an anaerobic mixed microbial community under pressurized conditions.

In the biomethane production method of the present invention, step (a) includes a check valve installed on the substrate supply pipe according to the volume of the head space above the first methanation reactor measured in the first methanation reactor. By opening and closing, the amount of the substrate for the methanation reaction supplied from the organic acid fermentation tank can be adjusted.

Before step (b), the concentration of hydrogen remaining in the first methanation reactor after step (a) is monitored, and the amount of hydrogen supplied to the second methanation reactor is adjusted according to the measured concentration of residual hydrogen. It may further include doing.

In the biomethane production method of the present invention, after step (b), (c) recovering the biomethane produced in step (b) and moving to a biomethane storage tank through a biomethane recovery pipe for storage can do.

The hydrogen supply tank may inject hydrogen into the first methanation reactor and the second methanation reactor in a continuous batch or semi-continuous manner.

It is preferable that nutrients necessary for culturing the anaerobic mixed microorganism community are supplied from the nutrient storage tank during the (a) and (b) steps.

The biomethane production system of the present invention uses organic wastes and intermediate metabolites generated in the wheat fermentation process of hydrolysis of organic wastes as a substrate, and biogas produced by performing a biological methanation reaction one or more times. There is an effect of increasing the content of heavy methane gas to produce high-purity methane gas.

In addition, the biomethane production method using the biomethane production system of the present invention does not require a separate purification process to obtain high-purity methane, and the biogas produced in the proposed biomethane production system is circulated and the methanation reaction is performed. There is a technical effect that is economically easy because additional processes can be easily performed by continuously performing the process.

1 is a flow chart of a biomethane production system for producing high-purity biomethane according to an embodiment of the present invention.
2 is a schematic diagram showing an anaerobic metabolic pathway for decomposing organic matter.
3 is a flow chart of a method for producing high-purity biomethane according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings, but these descriptions are only examples of the present invention, and the scope of the present invention is not limited to these descriptions.

The biomethane production system of the present invention applies an organic acid, which is a biochemical substance, as an inorganic reducing agent in the methanation reaction in the anaerobic fermentation process of organic matter, and performs the biomethane production process in multiple steps by a methanation reaction using an anaerobic mixed microorganism community, It is to produce high-purity biomethane.

1 shows a flow chart of a biomethane production system for producing high-purity biomethane of the present invention.

As shown in Figure 1, the biomethane production system of the present invention is largely, a methanation reaction tank 100 for performing a methanation reaction, an organic acid fermentation tank 200 providing a substrate for the methanation reaction in the methanation reaction tank, It includes a hydrogen supply tank 300, a nutritional substance storage tank 400, a biomethane storage tank 500, a control unit 610, 620, 630, a monitoring unit 710, 720, 730, and the like.

The organic acid fermentation tank 200 generates organic waste for use as a substrate for a methanation reaction, and an organic acid that is an intermediate metabolite of the hydrolysis and acid generation process of the organic waste, and the methanation reaction in the methanation reactor 100 It can be applied simultaneously as a substrate for microorganisms and sludge contributing to the methanation reaction as an inorganic reducing agent of.

Figure 2 is a schematic diagram showing briefly the anaerobic metabolic pathway for decomposing organic matter. As shown in FIG. 2, organic acids such as acetic acid and butyrate, which are intermediate metabolites generated in the anaerobic fermentation process of organic wastes (organic matters) and organic wastes, according to the anaerobic metabolic pathways decomposed by organic matters. methane (CH ₄₎ and carbon dioxide biogas carbon dioxide (CO ₂₎ containing with the (CO ₂₎ on the basis with the use of hydrogen (H ₂₎ supplied from the outside through chemical mechanisms, such as the scheme 1 below, the methane ( By _{converting to CH 4} ), the content of methane gas can be improved.

[Scheme 1]

CO ₂ + 4H ₂ →CH ₄ + 2H ₂ O

Organic acid, an intermediate metabolite of organic waste generated in the organic acid fermentation tank 200, is an accelerator that replaces hydrogen and electricity, which are other reducing agents for improving the quality of biomethane and increasing the efficiency of the bio-methanization system, or activating the action of other reducing agents. It can be applied to the methanation process as a stimulating aid.

In the organic acid fermentation tank 200, a mixed microbial community that favors anaerobic conditions separated from the natural world is adjusted in real time at a medium temperature of about 15°C to 25°C and a high temperature of 30°C to 60°C. Organic acids produced from organic waste by monitoring the environment inside the organic acid fermentation tank by measuring including measurement sensors that measure environmental factors such as (Hidraulic retention time, HRT), and controlling them through control units (610, 620, 630), etc. It can induce the production of substrates by methanation reactions such as products such as acetic acid (acetate) and butyrate (butyrate), which are major constituents.

In the biomethane production system of the present invention, the organic acid fermentation tank 200 is not shown in the drawing, but an acid-generating fermentation tank to further induce organic acids such as acetic acid and butyrate, which are major components of the organic acid, is added. Can be included as.

The substrate for the methanation reaction, which is an intermediate metabolite between organic waste and organic waste generated in the organic acid fermentation tank 200, is supplied to the methanation reaction tank 100 through a substrate supply pipe 10 formed on one side of the organic acid fermentation tank 200. do.

The methanation reaction tank 100 produces biomethane by performing a methanation reaction using an anaerobic mixed microorganism community, and the methanation reaction tank 100 is provided in plural, and each of the neighboring reaction tanks is connected to each other. Can be connected. As shown in FIG. 1, it may include a first methanation reactor 110 and a second methanation reactor 120.

The'anaerobic mixed microbial community' used in the methylation reaction in the present invention refers to a mixed microbial community that prefers anaerobic conditions separated from the natural world.

In the methanation reaction tank 100, the first methanation reaction tank 110 receives the substrate for the methanation reaction from the organic acid fermentation tank 200, and receives hydrogen from the hydrogen supply tank and uses the anaerobic mixed microorganism community. This is a methanation reactor that produces biogas containing methane and carbon dioxide by performing a methanation reaction.

The second methanation reactor 120 receives the biogas including methane and carbon dioxide produced from the first methanation reactor 110 through the connection pipe 60 and receives carbon dioxide in the biogas using the anaerobic mixed microorganism community. This is a methanation reactor that produces high-purity methane by performing a secondary methanation reaction that converts methane to methane, thereby improving the methane content.

On the substrate supply pipe 10 connecting the first methanation reactor 110 and the organic acid fermentation tank 200, an opening/closing valve 210 to open and close the supply of the methanation reaction substrate transferred from the organic acid fermentation tank for control. ), it is preferable that a spring loaded check valve is installed.

The opening/closing valve 210 may control the opening and closing of the relay valve 210 according to the hydraulic residence time (HRT) in consideration of optimization of the biomethane production system process, ease of control, and the like.

The hydrogen supply tank 300 stores hydrogen gas and is methanated through hydrogen supply pipes 21 and 22 in each of the first and second methanation tanks 110 and 120 of the methanation tank 100. Hydrogen is injected in a continuous batch or semi-continuous manner using a spurger located inside or outside the reaction tank.

Hydrogen supply through the hydrogen supply tank 300 is located at the top of the first methanation tank 110 and the second methanation tank 120 to facilitate conversion to methane by reacting with carbon dioxide inside the methanation tank. Hydrogen is injected until a valve such as a spring loaded check valve, which is elastically supported by a spring to open and close by the pressure inside the methanation reactor, increases the pressure to at least 4 atmospheres inside the methanation reactor. Is induced to increase the solubility of hydrogen and carbon dioxide. The valve used herein is not limited thereto, and various valves or regulators controlled by a pressure capable of turning on/off the pressure may be used. The hydrogen supply to the hydrogen supply tank 300 is controlled by the hydrogen supply amount control and monitoring unit 730.

The second methanation reactor 120 receives the biogas recovered from the first methanation reactor to further improve the methane content in the biogas, and receives hydrogen from the hydrogen supply tank under pressurized conditions. It is desirable to operate to produce biomethane.

In one embodiment, the biogas collected from the first methanation reactor 110 is injected into the second methanation reactor 120 controlled to at least 8 atmospheres, and hydrogen is continuously batched using a sparger. Alternatively, by injecting and reacting in a semi-continuous manner, the content of methane is increased to induce high purity of methane.

In order to smoothly perform the pressurized methanation reaction performed in the first methanation tank 110 and the second methanation tank 120 included in the methanation tank 100, a mechanical It is preferable that a stirring device is included. In addition, the head space above the first methanation reactor 110 and the second methanation reactor 120 is 20% or more and less than 50% based on 100% of the total volume of the total methanation reactor. It is preferable to be.

A nutrient supply pipe 30 is formed at one side of the first methanation reactor 110 and the second methanation reactor 120, so that nutrients necessary for cultivation of the anaerobic mixed microorganism community are stored and supplied to the methanation reactor. By continuously supplying nutrients from the nutrient storage tank, the methanation reaction is carried out smoothly.

_{Water (H 2} O) formed as a result of the methanation reaction of the methanation reaction tank is formed with treated water discharge pipes 41 and 42 on another side of the first methanation tank 110 and the second methanation tank 120 Unnecessary other substances, including

The biomethane storage tank 500 may recover and store high-purity biomethane gas produced through the second methanation reaction tank 120.

Organic waste for use as a methanation reaction substrate and organic acid fermentation tank 200 that generates intermediate metabolites of the organic waste, and methanation reaction by culturing an anaerobic mixed microorganism community by receiving a methanation reaction substrate from the organic acid fermentation tank A methanation reaction tank 100 for producing biomethane by performing, a hydrogen supply tank 300 for storing hydrogen gas and injecting hydrogen into the methanation reaction tank 100 in a continuous batch or semi-continuous manner, the organic acid fermentation tank interior A monitoring unit (710, 720, 730) that monitors the environmental conditions of and the environmental conditions inside the methanation reactor in real time, and a controller (610, 620) that adjusts the environmental conditions measured by the monitoring unit according to a preset criterion. 630), a nutrient material storage tank 400 that stores nutrients necessary for cultivation of an anaerobic mixed microorganism community and supplies them to the methanation reactor, and a biomethane storage tank that recovers and stores biomethane gas from the methanation reactor 100 It may include 500. The configuration of the biomethane production system described herein is not necessarily limited thereto, and a configuration capable of producing and managing biomethane may be additionally provided, including an additional organic acid fermentation tank, a medulization reactor, a monitoring unit, a control unit, and a storage tank. I can.

In the biomethane production system of the present invention, the methanation reaction tank 100 is supplied with a substrate for a methanation reaction from the organic acid fermentation tank 200, and hydrogen is supplied from the hydrogen supply tank, and the first using an anaerobic mixed microorganism community A first methanation reaction tank 110 that produces biogas containing methane and carbon dioxide by performing a methanation reaction, and an anaerobic mixed microorganism community by receiving the biogas produced from the first methanation reaction tank 110 It is preferable to include a second methanation reactor 120 for generating biomethane having an improved methane content by performing a second methanation reaction using.

The second methanation reactor 120 receives the biogas recovered from the first methanation reactor 110 in order to improve the content of methane, and receives hydrogen from the hydrogen supply tank 300 under pressurization conditions. It is desirable to produce biomethane by operating under

In the biomethane production system of the present invention, the first methanation reactor 110 and the second methanation reactor 120 included as the methanation reactor are preferably configured to include a mechanical stirring device therein.

The head space above the first methanation reactor 110 and the second methanation reactor 120 is 20% or more and less than 50% based on 100% of the total volume of the total methanation reactor. It is preferred, and more preferably, the volume of the head space is 20% based on 100% of the total volume of the total methanation reactor.

If the volume of the head space of the upper methanation reactor is out of the standard range suggested above, the supply of hydrogen is not smooth and the reaction between carbon dioxide and hydrogen is not performed properly, and the methanation reaction is not performed properly. It is desirable to satisfy the stated range.

The first methanation reactor 110 and the second methanation reactor 120 check the remaining hydrogen through a monitoring unit installed at one side, and the first methanation reactor 110 through the concentration of the confirmed residual hydrogen. And the amount of hydrogen supplied to the second methanation reactor 120 may be adjusted.

3 is a flow chart of a high purity biomethane production method using the biomethane production system of the present invention as viewed above.

As shown in FIG. 3, the biomethane production method of the present invention includes (a) performing a first methanation reaction using an anaerobic mixed microorganism community in a first methanation reactor to produce biogas containing methane and carbon dioxide. Step (S100), adjusting the amount of hydrogen supplied to the second methanation reactor according to the concentration of residual hydrogen remaining in the first methanation reactor after step (a) (S110), (b) second Producing biomethane by supplying the biogas generated and recovered in step (a) to the methanation reactor to perform a secondary methanation reaction using the anaerobic mixed microorganism community (S200), and (c) the (b) The biomethane produced in step) may be recovered and transferred to the biomethane storage tank through the biomethane recovery pipe and stored in the order of step S300.

In the biomethane production method of the present invention, the (a) step (S100) is to transfer the substrate for the methanation reaction from the organic acid fermentation tank 200 to the substrate supply pipe 10 in the first methanation reactor 110 of the biomethane production system. This is a step of producing biogas containing methane and carbon dioxide by supplying and supplying hydrogen from a hydrogen supply tank to perform a first methanation reaction using an anaerobic mixed microorganism community.

Then, in step (b) (S200), the biogas produced in step (a) is supplied to the second methanation reactor 120, hydrogen is supplied from the hydrogen supply tank, and the anaerobic mixed microorganism community is formed under pressurized conditions. This is a step of producing biomethane by performing a secondary methanation reaction using it.

Before performing the (b) step (S200), supply to the second methanation reactor 120 according to the concentration of residual hydrogen remaining in the first methanation reactor 110 after the step (a) (S100). You can adjust the amount of hydrogen to be made.

And (c) step (S300) performs an exaggeration of recovering the biomethane produced through the (b) step (S200), moving it to the biomethane storage tank 500 through the biomethane recovery pipe 50, and storing it. It produces high-purity biomethane with high methane content in biogas.

As described above, the biomethane production system of the present invention, which is properly operated by receiving an intermediate metabolite generated during the hydrolysis and fermentation process of organic waste and organic waste, has a methane content of at least 30% or more depending on the purpose. And can produce up to 98% high purity methane. The methanation reactor, which reacts by receiving an organic substrate directly, uses microbial communities and sludge that grow well under anaerobic conditions as a planting source, and increases methanation by injecting hydrogen into the methanation reactor at medium or high temperature conditions at a pH of 8.5 or less. Can induce

10: substrate supply pipe
21, 22: hydrogen supply pipe
30: nutrition supply pipe
41, 42: treated water discharge pipe
50: biomethane recovery pipe
60: connector
100: methanation reactor
110: first methanation reactor
120: second methanation reactor
200: organic acid fermentation tank
210: on-off valve
300: hydrogen storage tank
400: spiritual substance storage tank
500: biomethane storage tank
610: HRT control unit
620: pH control unit
630: temperature control unit
710: emission gas monitoring unit
720: methane monitoring unit
730: hydrogen supply amount control and monitoring unit

Claims (13)

An organic acid fermentation tank for generating organic waste for use as a substrate for a methanation reaction and an intermediate metabolite of the organic waste;
A methanation reactor for producing biomethane by performing a methanation reaction by receiving a methanation reaction substrate from the organic acid fermentation tank and culturing an anaerobic mixed microorganism community;
A hydrogen supply tank for storing hydrogen gas and injecting hydrogen into the methanation reactor in a continuous batch or semi-continuous manner;
A monitoring unit monitoring the environmental conditions inside the organic acid fermentation tank and the environmental conditions inside the methanation reactor in real time;
An adjustment unit for adjusting the environmental conditions measured by the monitoring unit according to a preset standard;
A nutrient material storage tank for storing nutrients necessary for cultivation of the anaerobic mixed microbial community and supplying them to the methanation reactor; And
A biomethane production system comprising: a biomethane storage tank for recovering and storing biomethane gas from the methanation reaction tank. The method of claim 1,
The methanation reactor,
First methane for producing biogas containing methane and carbon dioxide by receiving a methanation reaction substrate from the organic acid fermentation tank and performing a first methanation reaction using an anaerobic mixed microorganism community by receiving hydrogen from the hydrogen supply tank A reaction tank; And
Containing; a second methanation reactor for generating biomethane having an improved methane content by performing a second methanation reaction using an anaerobic mixed microorganism community by receiving the supply of the biogas produced from the first methanation reactor. Biomethane production system, characterized in that. The method of claim 2,
The second methanation reactor,
A biomethane production system, characterized in that, in order to improve the content of methane, the biogas recovered from the first methanation reaction tank is supplied, and hydrogen is supplied from the hydrogen supply tank and operated under pressurized conditions to produce biomethane. The method of claim 2,
The biomethane production system, characterized in that the first methanation reactor and the second methanation reactor include a mechanical stirring device therein. The method of claim 2,
A biomethane production system, characterized in that the head space above the first methanation reactor and the second methanation reactor is 20% or more and less than 50% based on 100% of the total volume of the total methanation reactor. . The method of claim 1,
A substrate supply pipe connecting the methanation reactor and the organic acid fermentation tank, and supplying a methanation reaction substrate from the organic acid fermentation tank to the methanation reactor;
A hydrogen supply pipe formed on one side of the methanation reactor to supply hydrogen gas from the hydrogen supply tank;
A nutrient supply pipe connected to the other side of the methanation reactor to supply nutrients necessary for culturing the anaerobic mixed microorganism community from the nutrient storage tank;
A treated water discharge pipe for discharging the treated water used in the methanation reaction in the methanation reactor; And
And a biomethane recovery pipe for recovering the biomethane produced by the methanation reaction in the methanation reactor and transferring it to the biomethane storage tank. The method of claim 6,
A biomethane production system, characterized in that a check valve is installed on the substrate supply pipe to open and close the supply of the substrate for the methanation reaction supplied from the organic acid fermentation tank for control. (a) The first methanation reaction tank is supplied with the substrate for the methanation reaction from the organic acid fermentation tank through the substrate supply pipe, and hydrogen is supplied from the hydrogen supply tank to perform the first methanation reaction using the anaerobic mixed microorganism community to methane and carbon dioxide Producing a biogas comprising a; And
(b) supplying the biogas produced in step (a) to the second methanation reaction tank, supplying hydrogen from the hydrogen supply tank, and performing a second methanation reaction using an anaerobic mixed microbial community under pressurized conditions to produce biomethane. Producing a; biomethane production method comprising a. The method of claim 8,
The step (a),
Adjusting the amount of the methanation reaction substrate supplied from the organic acid fermentation tank by opening and closing a check valve installed on the substrate supply pipe according to the volume of the head space above the first methanation reactor measured in the first methanation reactor. Biomethane production method characterized in that. The method of claim 8,
Before step (b), the concentration of hydrogen remaining in the first methanation reactor after step (a) is monitored, and the amount of hydrogen supplied to the second methanation reactor is adjusted according to the measured concentration of residual hydrogen. Biomethane production method, characterized in that. The method of claim 8,
After step (b),
(c) recovering the biomethane produced in step (b), moving it to a biomethane storage tank through a biomethane recovery pipe, and storing it. The method of claim 8,
The hydrogen supply tank,
Biomethane production method, characterized in that injecting hydrogen into the first methanation reactor and the second methanation reactor in a continuous batch or semi-continuous manner. The method of claim 8,
Biomethane production method, characterized in that the nutrients required for culturing the anaerobic mixed microbial community are supplied from the nutrient storage tank during the (a) and (b) steps.

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