JP2003033781A - System for methane gas production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system capable of carrying out methane fermentation efficiently and quickly, and decreasing installation cost and running and maintenance costs by means of using a small methane fermentation tank whereby eliminating the use of unnecessary equipment such as a dehydrator. SOLUTION: This system is equipped with a raw waste-solubilizing and extracting tank 1 capable of obtaining a liquid, wherein organic matter is dissolved in, by the treatment of raw waste in the presence of anaerobic bacteria, an acid production tank 2 capable of obtaining water containing organic acids formed by decomposition of organic matter in the liquid from the raw waste- solubilizing and extracting tank 1 with anaerobic bacteria, a methane fermentation tank 7 to produce methane gas by fermentation of organic acids dissolved in the water from the acid production tank 2 with methane-producing bacteria, and a treated water tank 18 which treats water from the methane fermentation tank 7 and a part thereof is discharged and the rest is fed back to the raw waste-solubilizing and extracting tank 1 and is sprinkled thereto.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a methane gas generation system.

[0002]

2. Description of the Related Art Conventionally, organic waste such as food waste is fermented to extract methane gas, and the obtained methane gas is effectively utilized as electric energy or heat energy by a cogeneration system or the like. .

An example of a conventional methane gas production system is shown in FIG. In the figure, a is a wet pulverizing / sorting device configured to generate organic slurry while garbage containing raw garbage is input, b is a slurry storage tank for storing the organic slurry sent from the wet pulverizing / sorting device a, c is a methane fermentation tank for fermenting the organic slurry fed from the slurry storage tank b to generate methane, d is a methane gas storage tank for storing the methane gas generated in the methane fermentation tank c, and e is a methane fermentation tank c. A digestive liquid storage tank for storing the digested liquid from which methane gas has been taken out, f is a dehydrator for dehydrating the digested liquid from the digestive liquid storage tank e to which a coagulant is added, and g is a composting device.

In the above-mentioned methane gas production system, the collected dust is put into a wet crushing / sorting device a to mix organic substances such as food waste with water and crushed, and at the same time, heavy substances such as stones and metals, plastics and cloths. Light materials such as are sorted and crushed into organic slurry, which is stored in the slurry storage tank b. Further, the organic slurry is quantitatively fed from the slurry storage tank b to the methane fermentation tank c, and in the methane fermentation tank c, the organic slurry is fermented to generate methane gas, and the generated methane gas is stored in the methane gas storage tank d. To be done. The methane gas stored in the methane gas storage tank d is taken out and sent to, for example, a cogeneration system, and is effectively used as electric energy or heat energy in the cogeneration system.

The digested liquid left after the methane gas is taken out in the methane fermentation tank c is stored in the digested liquid storage tank e, added with a coagulant and fed to the dehydrator f, and the desorbed liquid is removed by the dehydrator f. The dehydrated dehydrated sludge is fed to the composting device g.
The desorbed liquid is sent to the water treatment device, and the composting device g
The solid product obtained in step 1 becomes compost.

[0006]

In the above methane gas production system, since the organic acid is treated as a large amount of slurry in the methane fermentation tank c, it is difficult to efficiently and rapidly perform methane fermentation treatment to produce methane gas. is there. In addition, since it is necessary to process a large amount of organic slurry, the methane fermentation tank c becomes large, and an extra device such as a dehydrator f is required to process the digested liquid, resulting in equipment costs and operation and maintenance costs. It becomes expensive.

In view of the above-mentioned circumstances, the present invention enables efficient and rapid methane fermentation treatment to produce methane gas, and enables the use of a small methane fermentation tank as well as an extra dehydrator or the like. Equipment without the need for equipment
The purpose of the present invention is to provide a methane gas generation system that can reduce the operation and maintenance costs.

[0008]

The methane gas producing system according to claim 1 of the present invention is an organic dissolved product capable of producing water in which an organic substance is dissolved by decomposing an object containing the organic substance by an aerobic microorganism. An extractor, an acid-generating tank capable of generating water in which an acid such as an organic acid is dissolved by decomposing an organic substance dissolved in water from the organic melt extractor with an anaerobic microorganism, and the acid. It is provided with a methane fermentation tank capable of producing methane gas by fermenting an acid such as an organic acid dissolved in water from the production tank with a group of methanogenic bacteria.

In the methane gas production system according to the second aspect of the present invention, the water discharged from the methane fermentation tank is treated so that a part of the water is discharged and a part of the water is sent to the organic melt extractor for watering. It is equipped with a treated water tank.

A methane gas production system according to a third aspect of the present invention is provided with a pipe line for circulating a part of water from the methane fermentation tank at the bottom of the methane fermentation tank.

In the methane gas production system according to a fourth aspect of the present invention, the acid production tank is provided with a heater for heating the water in the acid production tank to a predetermined temperature.

According to a fifth aspect of the present invention, there is provided a methane gas production system, wherein a pipe for circulating a part of water from the methane fermentation tank to the bottom of the methane fermentation tank is provided with a predetermined temperature of water in the pipe. A heater for heating is provided.

The methane gas production system of claim 6 of the present invention is provided with means for feeding an alkaline solution into the methane fermentation tank when the pH of the water in the methane fermentation tank is lower than a predetermined value. Is.

In the methane gas production system according to claim 7 of the present invention, an aerobic microbial treatment tank is provided in a pipeline for sending water overflowed from the methane fermentation tank to the treated water tank.

In the present invention, in the organic melt extractor, the material to be treated containing the organic matter is decomposed by aerobic microorganisms to produce water in which the organic matter is dissolved, and in the acid generating tank, the organic melt extractor is used. The organic substances dissolved in the water are decomposed by anaerobic microorganisms to produce water in which the organic acids are dissolved.In the methane fermentation tank, the organic acids dissolved in the water from the acid generation tank are methanogenic bacteria. Fermentation by the group produces methane gas.

In the present invention, methane fermentation treatment can be performed efficiently and quickly to generate methane gas, and a small methane fermentation tank can be used, and an extra device such as a dehydrator is not required. Equipment costs and operation and maintenance costs are low.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an example of an embodiment for carrying out the present invention. Reference numeral 1 denotes a food waste melt extractor, and the food waste melt extractor 1 is a stirring blade 1b driven by a drive device 1a.
Is equipped with. Thus, in the garbage-dissolved-medium extractor 1, foreign materials (glass, metal, plastic, wood chips, paper, etc.) are removed and then put in (for example, food waste such as kitchen waste and leftover food). ) Is decomposed by the action of aerobic microorganisms, and water and carbon dioxide in which organic substances are dissolved are generated.

Reference numeral 2 is an acid production tank, and the acid production tank 2 is provided with a stirring blade 2b driven by a drive device 2a.
A temperature indicating controller 3 and a heater 4 are attached to the acid production tank 2 so that the temperature of water in the acid production tank 2 can be maintained at a predetermined temperature.

Thus, in the acid production tank 2, the organic matter in the water fed from the garbage-dissolved matter extractor 1 is decomposed by the action of anaerobic microorganisms, and acetic acid, propionic acid, butyric acid, lactic acid, etc. The organic acid of is produced.

Reference numeral 5 denotes a pump capable of intermittent operation, and water containing organic acid produced in the acid producing tank 2 is supplied by the pump 5 to
It can be fed to the methane fermentation tank 7 through a pipe 6 as appropriate. Further, as the methane fermentation tank 7, for example, an upflow anaerobic sludge bed type reactor or an anaerobic fixed bed reactor is used, and the organic acid in the water is fermented by the methanogenic bacteria group in the methane fermentation tank 7. It produces methane gas.

Reference numeral 8 is a circulation pipe for circulating a part of the water containing the organic acid in the methane fermentation tank 7 to the downstream side of the pump 6 in the pipe 6 by the pump 9. Also, the heater 10 and the temperature indicating controller 11 are sequentially connected in the flow direction so as to be located on the upstream side in the flow direction, and the pH indicating controller 12 is connected to the downstream side of the pump 9.

Then, a part of the water taken out from the methane fermentation tank 7 is fed through the circulation pipe line 8 and again fed from the pipe line 6 to the methane fermentation tank 7. This is to prevent the solid matter contained in water from settling and accumulating at the bottom of the methane fermentation tank 7. When the temperature of the water flowing through the circulation pipe line 8 detected by the temperature indicating controller 11 is lower than a predetermined temperature, the heater 10 is activated by a command from the temperature indicating controller 11 and the circulating pipe The water containing the organic acid flowing in the passage 8 can be heated to a predetermined temperature. Further, the water having a high concentration of organic acid from the pump 5 is converted into the methane fermentation tank 7 by the water having a low concentration of organic acid from the pump 9.
It is designed to be diluted on the inlet side.

Reference numeral 13 is an alkaline solution tank, 14 is a pump connected to an intermediate portion of a pipe line 15 which connects the alkaline solution tank 13 and the pipe line 6 downstream of the connecting portion of the pipe line 8, and a pH indicator controller 12 When the pH of the water in the circulation line 8 detected in step 1 is lower than a predetermined value, the pump 14 is activated by a command from the pH indicator controller 12, and the alkaline solution (for example, caustic soda) in the alkaline solution tank 13 is pumped. The pH can be adjusted to a predetermined value by feeding the methane from the channels 6 and 15 into the methane fermentation tank 7.

Reference numeral 16 is a hydrogen sulfide removal tower installed in the latter stage of the methane fermentation tank 7, and 17 is a gas holder for storing the methane gas from which the hydrogen sulfide has been removed by the hydrogen sulfide removal tower 16.
Thus, the methane gas stored in the gas holder 17 is appropriately sent to, for example, a cogeneration system, and is effectively used as electric energy or heat energy in the cogeneration system.

Reference numeral 18 denotes a treated water tank that stores treated water that has overflowed from the methane fermentation tank 7 and is capable of discharging sewage. The water that overflowed the treated water tank 18 is expected to have a fertilizer effect or a hydroponic effect. It can be used as irrigation water.

Reference numeral 19 is a pump connected to a midway portion of the pipe 20 for feeding the treated water from the treated water tank 18 from the pipe 20 to the sprinkler header 1c of the melt extractor 1. Note that W is makeup water that supplements the water that overflows from the treated water tank 18 and is drained.

Next, the operation of the illustrated example will be described. The raw garbage (for example, food waste such as kitchen waste and leftover food) from which foreign substances (glass, metal, plastic, wood chips, paper, etc.) have been removed is put into the raw garbage melt extractor 1 and driven by the drive unit 1a. Is stirred by the stirring blade 1b driven by the above, together with the wood-based material such as rice husks and sawdust in the raw garbage melt extractor 1. Therefore, the aerobic microorganisms adhering to the wood-based material such as chaff and sawdust decompose the food waste into dissolved organic matter, and produce water and carbon dioxide gas in which the organic matter is dissolved. Thus, the carbon dioxide gas is discharged to the outside, and the water in which the organic matter is dissolved is sent to the acid generation tank 2. At this time, the water or makeup water W from the treated water tank 18 is jetted from the sprinkling header 1c into the kitchen waste melt extractor 1.

The organic matter dissolved in the water sent to the acid production tank 2 is stirred by the drive device 2a.
While being stirred by b, it is decomposed by anaerobic microorganisms in the acid production tank 2 to produce an organic acid such as acetic acid, propionic acid, butyric acid, lactic acid, etc. It is sent to the methane fermenter 7 through it.

When the temperature of the water in the acid production tank 2 detected by the temperature indicating controller 3 is lower than a predetermined value,
A command is given from the temperature indicating controller 3 to the heater 4, the heater 4 is turned on, and the temperature of the water in the acid generation tank 2 is heated to a predetermined temperature. For example, when the methanogenic bacteria group used in the methane fermentation tank 7 is a mesophilic bacterium, the temperature of the water in the acid generator tank 2 is adjusted to about 37 ± 5 ° C., and the methanogenic bacteria group used in the methane fermentation tank 7 has a high temperature. In the case of bacteria, the temperature of water in the acid production tank 2 is adjusted to about 54 ± 3 ° C. These temperatures are temperatures at which the methanogenic bacteria group can actively operate in the methane fermentation tank 7.

The organic acid dissolved in the water sent to the methane fermentation tank 7 is fermented by the methanogenic bacteria group in the methane fermentation tank 7 to obtain methane gas, and the obtained methane gas is the methane fermentation tank. 7 to hydrogen sulfide removal tower 1
6, the hydrogen sulfide removal tower 16 removes hydrogen sulfide, and the gas is fed to the gas holder 17.
7 is fed to the cogeneration system, for example, and is effectively used as electric energy or heat energy in the cogeneration system.

Further, the water flowing out from the upper part of the methane fermentation tank 7 after the production of methane gas is sent to the treated water tank 18 to precipitate the solid matter contained in the water, and the water from which the solid matter is removed is The treated water overflows the treated water tank 18 and is drained, and is used as agricultural irrigation water, expecting a fertilizer effect and a hydroponic effect. This is because the wastewater contains fertilizing components such as nitrogen, phosphorus and metal salts and can be used as fertilizer.

A part of the water from the treated water tank 18 is sent through the pipe 20 by the pump 19 and is sprayed from the water sprinkling header 1c to the raw garbage dissolved matter extractor 1 to generate water in which organic matters are dissolved. Be served.

A part of the water in the methane fermentation tank 7 is taken out from the upper side portion to the circulation pipeline 8 and circulated by the pump 9 through the circulation pipeline 8 and the pipeline 6 to the lower portion of the methane fermentation tank 7. . Therefore, it is possible to prevent the solid matter from settling on the bottom of the methane fermentation tank 7 due to the state that the vicinity of the bottom of the methane fermentation tank 7 is stirred by the circulating water.

When the temperature of the water in the circulation pipe 8 detected by the temperature indicating controller 11 is lower than a predetermined temperature, the temperature indicating controller 11 gives a command to the heater 10 to turn on the heater 10. Is turned on, and the water in the circulation line 8 is heated to a predetermined temperature. For example, methane fermentation tank 7
When the methanogenic bacteria group used in step 3 is mesophilic, the temperature of the water in the circulation line 8 and, in turn, the temperature in the methane fermentation tank 7 is 3
When the methane-producing bacteria used in the methane fermentation tank 7 are thermophilic bacteria, the temperature of the water in the circulation pipe 8 is adjusted to about 54 ± 3 ° C. As in the case described above, these temperatures are temperatures at which the methanogenic bacteria group can actively activate in the methane fermentation tank 7.

Circulation line 8 detected by pH indicator controller 12
When the pH of the water inside is lower than the predetermined value, a command is given to the pump 14 and the pump 14 is driven. Therefore, the alkaline solution in the alkaline solution tank 13 is fed into the methane fermentation tank 7 from the pipes 15 and 6 by the pump 14.
The pH of the water in the methane fermentation tank 7 is maintained at a predetermined value.
By the way, for good fermentation of methane, the pH is 6.4.
The position of -7.2 is preferable.

According to the above-mentioned illustrated example, liquefaction decomposition progresses, the amount of solids is small, and the viscosity is reduced as compared with the case of treating the organic slurry as in the conventional case. Therefore, the methane fermentation treatment is performed efficiently and promptly to produce methane gas. Can be generated,
In addition, since a small methane fermentation tank can be used and an extra device such as a dehydrator is not required, the facility cost and the operation and maintenance cost can be reduced.

[Example] If the input amount of raw garbage to the raw garbage dissolved substance extractor 1 is 1 kg / day (about 9.8 N / day) and the water injection amount is 25 liters / day, the raw garbage dissolved substance extractor 1
The amount of wastewater discharged from the plant is 26 liters / day, CO contained in the wastewater
D _cr is 10,000 mg / liter (0.098 N /
Liter), the amount of wastewater from the acid generation tank 2 is 25 liters /
The COD _cr contained in the effluent is 10,000 mg / liter (0.098 N / liter), the amount of methane gas generated in the methane fermentation tank 7 is 120 liters / day, and the methane fermentation tank 7 supplies the treated water tank 18 with water. COD in wastewater
_cr is 500 mg / liter (0.0049 N / liter), COD in the wastewater discharged from the treated water tank 18.
_cr becomes 500 mg / liter (0.0049 N / liter).

In the methane gas production system of the present invention, the case of treating food waste has been described.
Not only garbage but also applicable to the disposer kitchen drain from the disposer device, for example,
As shown in FIG. 1, the line for sending the water overflowed from the methane fermentation tank 7 to the treated water tank 18 may be provided with an aerobic microbial treatment tank 21 as shown by a phantom line. Needless to say, various changes can be made without departing from the scope of the invention.

[0039]

As described above, the first aspect of the present invention is as described above.
According to the methane gas production system described in 1 to 7, methane fermentation treatment can be performed efficiently and rapidly to produce methane gas, and a small-sized methane fermentation tank can be used and an extra dehydrator or the like can be used. Since the device is unnecessary, the excellent effect that the equipment cost and the operation and maintenance cost are low can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart showing an outline of an example of an embodiment of a methane gas production system of the present invention.

FIG. 2 is a flowchart showing an example of a conventional methane gas generation system.

[Explanation of symbols]

1 Garbage Melt Extractor (Organic Melt Extractor) 2 Acid Generation Tank 4 Heater 7 Methane Fermenter 8 Circulation Pipeline (Pipeline) 10 Heater 13 Alkaline Solution Tank (Means for Feeding Alkaline Solution) 14 Pump (means for feeding alkaline solution) 15 Pipeline (means for feeding alkaline solution)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoji Koshiba             3-4-1 Yurakucho, Chiyoda-ku, Tokyo             Machine Industry Co., Ltd. (72) Inventor Akihiro Nagano             3-4-1 Yurakucho, Chiyoda-ku, Tokyo             Machine Industry Co., Ltd. (72) Inventor Tsuneo Maki             1-1-1 Sakuragaoka, Setagaya-ku, Tokyo School             Corporate Tokyo University of Agriculture (72) Inventor Shoji Suzuki             1-1-1 Sakuragaoka, Setagaya-ku, Tokyo School             Corporate Tokyo University of Agriculture F-term (reference) 4D004 AA03 CA13 CA15 CA19 CB04                       CB28                 4D040 AA02 AA26 AA32 AA45 AA53                       AA55 AA62 AA63

Claims (7)

[Claims] 1. An organic melt extractor capable of generating water in which organic matter is dissolved by decomposing an object to be treated containing an organic matter by an aerobic microorganism, and dissolving in water from the organic melt extractor. An acid generating tank capable of generating water in which an acid such as an organic acid is dissolved by decomposing an organic substance that is present by an anaerobic microorganism, and an acid such as an organic acid that is dissolved in water from the acid generating tank. A methane gas production system, comprising: a methane fermentation tank capable of producing methane gas by fermenting with a group of methanogenic bacteria. 2. A treated water tank for treating the water flowing out from the methane fermentation tank to drain a part of the water and to feed a part of the water to an organic melt extractor for water spraying. The methane gas generation system described in. 3. The methane gas generation system according to claim 1 or 2, wherein a pipe is provided to circulate a part of the water from the methane fermentation tank at the bottom of the methane fermentation tank. 4. The methane gas generation system according to claim 1, wherein the acid generation tank is provided with a heater for heating the water in the acid generation tank to a predetermined temperature. 5. A pipe for circulating a part of the water from the methane fermentation tank to the bottom of the methane fermentation tank is provided with a heater for heating the temperature of the water in the pipe to a predetermined temperature. 1,
The methane gas generation system according to 2, 3 or 4. 6. A means for feeding an alkaline solution into the methane fermenter when the pH of the water in the methane fermenter is lower than a predetermined value. The methane gas generation system described in. 7. The methane gas production system according to claim 1, wherein an aerobic microbial treatment tank is provided in a pipeline for sending water overflowed from the methane fermentation tank to the treated water tank.