JP4834563B2 - Methane fermentation system and method - Google Patents

Description

  The present invention relates to a methane fermentation system and method for methane fermentation of organic waste in a methane fermenter.

  As a technology for processing organic waste such as livestock waste and garbage, methane fermentation treatment using anaerobic methane-producing bacteria in an anaerobic methane fermentation tank (anaerobic digestion) Is known and can recover biogas (gas mainly composed of methane produced by the metabolism of anaerobic microorganisms) and use it as recycled energy. It is positioned as one of the energy resources and is expected to spread in the future.

  When performing the methane fermentation treatment, in order to increase the methane fermentation efficiency, a large solubilization treatment tank is provided in the front stage of the methane fermentation tank, and before the methane fermentation treatment in the methane fermentation tank, In other words, a method has been adopted in which organic waste is solubilized by performing a decomposition treatment (aerobic treatment) using an aerobic bacterium to facilitate the subsequent methane fermentation treatment (Patent Document 1: Japanese Patent Laid-Open No. 2003-2003). 164840).

In Europe and the like, the solubilization treatment in the solubilization treatment tank as described above is not performed, but methane fermentation is promoted by adding a hydrolase (cellulose-degrading enzyme) to the methane fermentation tank, thereby improving the methane fermentation efficiency. A method for further improving the above has been studied.
JP 2003-164840 A

  The solubilization treatment by the solubilization treatment tank described in Patent Document 1 is a pretreatment to be performed on the total amount of organic waste before being supplied to the methane fermentation tank, and a large solubilization of the same scale as the methane fermentation tank. A treatment tank must be installed.

In addition, in the method of adding an enzyme to the methane fermentation tank, it is not necessary to provide a solubilization treatment tank, so it is possible to install equipment necessary for the methane fermentation system in a small space, and the installation cost of equipment and the like can be suppressed. .
However, the enzyme that promotes methane fermentation is very expensive, and the enzyme has to be continuously added.

  An object of the present invention is to provide a methane fermentation system and method that do not require a large-sized solubilization tank and can improve the methane fermentation efficiency in the methane fermentation tank without adding an enzyme to the methane fermentation tank. Is to provide.

  In order to achieve the above object, a methane fermentation system according to a first aspect of the present invention includes a methane fermentation tank for methane fermentation of an organic waste under anaerobic conditions, and a methane fermentation solution in the methane fermentation tank. An aerobic culture tank in which an aerobic bacterium is cultured under an aerobic condition by sending a part and a nutrient source, so that the culture solution cultured in the aerobic culture tank is returned to the methane fermentation tank It is structured.

In the methane fermentation tank, anaerobic methane-producing bacteria are grown and methane fermentation is carried out. In the fermentation liquid in the methane fermentation tank, there are aerobic bacteria that cannot grow under anaerobic conditions. Exists.
According to the present invention, a part of the fermentation broth in the methane fermenter is extracted and transferred to the aerobic condition together with the nutrient source, so the aerobic bacteria contained in the extracted methane fermentation broth are Incubated under aerobic conditions. Thereby, a hydrolase is produced | generated by an aerobic microbe in a culture solution. The culture broth is returned again into the methane fermenter, and the hydrolyzing enzyme is hydrolyzed to organic waste even under anaerobic conditions by supplying the produced hydrolase to the methane fermenter. In the inside, hydrolysis of organic waste proceeds by the hydrolase, and methane fermentation by the methanogen progresses, so that methane fermentation efficiency can be improved.

Therefore, since it is not necessary to add an enzyme reagent to a methane fermentation tank, the maintenance cost for operating a methane fermentation system can be reduced.
Moreover, since it is not necessary to install a large solubilization processing tank for processing the whole amount of the organic waste before supplying to the methane fermentation tank, its introduction cost and maintenance cost are not required and it is economical.

  The methane fermentation system according to the second aspect of the present invention is the amount of organic waste supplied to the methane fermentation tank per unit time in the first aspect, and is discharged from the methane fermentation tank per unit time. 1 to 10% of the amount of methane fermenter supplied and discharged, which is the amount of methane fermentation broth, is sent from the methane fermenter to the aerobic culture tank.

  According to the present invention, the amount of the fermented liquid sent from the methane fermentation tank to the aerobic culture tank may be small with respect to the amount of organic waste to be treated in the methane fermentation tank, so that the organic waste supplied to the methane fermentation tank Compared to the solubilization tank for processing the whole quantity, the aerobic culture tank is small and the introduction cost and maintenance cost of the aerobic culture tank can be kept low.

In the methane fermentation system according to the third aspect of the present invention, in the first or second aspect, the culture residence time in the aerobic culture tank is 1 to 5 days.
Aerobic bacteria grow and produce hydrolase, and produce hydrolase in the culture solution that enhances methane fermentation efficiency. At that time, a sufficient amount of hydrolase is produced in the aerobic culture tank to improve the methane fermentation efficiency in the methane fermentation tank by the culture residence time for one day. When the culture residence time is 5 days, the amount of hydrolase produced is further increased, but the amount of the culture solution retained in the aerobic culture tank is also increased five times, and the aerobic culture tank is enlarged. It is desirable to set the upper limit to 5 days.

The methane fermentation system according to the fourth aspect of the present invention is the methane fermentation system according to any one of the first to third aspects, wherein the aerobic condition in the aerobic culture tank is aeration, mechanical agitation under open air, and / or Or it is ensured by culture solution circulation by a pump.
According to the present invention, the aerobic culture tank can be set to aerobic conditions necessary for the growth of aerobic bacteria.

The methane fermentation system according to the fifth aspect of the present invention is the methane fermentation system according to any one of the first to fourth aspects, wherein the nutrient source is at least one of polysaccharides, higher fatty acids, monosaccharides, disaccharides, amino acids, and fats and oils. One component is added so that it may become a density | concentration of 10 mg / liter or more with respect to the quantity of the methane fermentation liquid sent from the inside of a methane fermenter.
ADVANTAGE OF THE INVENTION According to this invention, while producing aerobic bacteria favorably, production of the hydrolase by this aerobic bacteria is performed favorably.

The methane fermentation system according to a sixth aspect of the present invention is the methane fermentation system according to any one of the first to fifth aspects, wherein the temperature of the culture solution in the aerobic culture tank is the temperature of the methane fermentation solution in the methane fermentation tank. It is characterized by being set within ± 5 ° C.
ADVANTAGE OF THE INVENTION According to this invention, the temperature change of the fermentation liquid in a methane fermentation tank at the time of returning the culture liquid in an aerobic culture tank in a methane fermentation tank can be decreased.

  In the methane fermentation method according to the seventh aspect of the present invention, a part of the methane fermentation solution in the methane fermentation tank for methane fermentation of organic waste and a nutrient source are sent to the aerobic culture tank, and the aerobic culture tank After culturing aerobic bacteria under aerobic conditions, the culture solution is returned to the methane fermentation tank. According to the present invention, the same effect as the first aspect can be obtained.

  According to the present invention, the methane fermentation efficiency in the methane fermentation tank can be improved without requiring a large-sized solubilization tank and without adding an enzyme to the methane fermentation tank.

[Example 1]
An embodiment of the methane fermentation system according to the present invention will be described in detail with reference to FIG.
The methane fermentation system of FIG. 1 includes a grinder 41 for grinding organic waste 1, a methane fermentation tank 11 for sending ground organic waste 1 and methane fermentation of organic waste 1. A part of the fermentation liquid 2 extracted from the methane fermentation tank 11 and the nutrient source 4 are sent, and an aerobic culture tank 21 for culturing aerobic bacteria under aerobic conditions, The culture solution 3 in the aerobic culture tank 21 is configured to be returned to the methane fermentation tank 11.

  Examples of the organic waste 1 used in the present invention include garbage, wastewater treatment sludge, livestock waste, and green farm waste. Here, livestock waste includes livestock manure, carcass, and processed products thereof. More specifically, livestock manure such as pigs, cattle, sheep, goats, chickens, and carcasses thereof, In addition to bone, meat, fat, internal organs, blood, brain, eyeballs, skin, hoofs, horns, etc. isolated from, such as bones, meat, etc. of livestock carcasses represented by meat and bone meal, meat meal, bone meal, blood meal etc. Also included are crushed crushed materials and dried products obtained by drying blood. Examples of other waste include household waste, industrial waste, agricultural and marine industrial waste, food processing waste, and the like. In addition, according to the state of the organic waste 1, a crushing process and a sorting process by a biaxial crusher can be performed as a pretreatment as necessary.

  The organic waste 1 is finely ground by the grinder 41 so that fermentation by the methanogen is easily performed. The ground organic waste 1 is supplied into the methane fermentation tank 11 from the organic waste supply port 12 via the organic waste supply line 10, and methane fermentation by the methane producing bacteria is performed in the methane fermentation tank 11. Done.

  While the ground organic waste 1 is supplied from the organic waste supply port 12 to the methane fermentation tank 11, the methane fermentation liquid 2 in the methane fermentation tank 11 is discharged from the methane fermentation liquid discharge port 13, It is sent to the slurry tank 42 and stored for several months. The amount of the organic waste 1 supplied to the methane fermentation tank 11 is the same amount as the amount of the methane fermentation liquid 2 discharged from the methane fermentation tank 11, and this is referred to as “methane fermentation tank supply / discharge amount” in the following description. Called.

  The temperature in the methane fermentation tank 11 is set to 55 ° C., and so-called high temperature methane fermentation is performed. The biogas produced by methane fermentation is sent to a purification process such as desulfurization. The residence time of the organic waste 1 in the methane fermentation tank 11 is set to, for example, 15 days (methane fermentation tank volume / methane fermentation tank supply / discharge amount = 15 days).

  Intermediate temperature methane fermentation can also be performed by setting the temperature in the methane fermentation tank 11 to 37 ° C. In that case, the residence time of the organic waste 1 in the methane fermentation tank 11 can be set to 35 days (methane fermentation tank volume / supply discharge amount = 35 days), for example.

  A part of the methane fermentation broth 2 in the methane fermentation tank 11 is extracted from the methane fermentation liquid outlet 14, sent via the methane fermentation liquid transfer line 20, and from the methane fermentation liquid supply port 22 to the aerobic culture tank 21. Supplied in. The amount of the methane fermentation liquid 2 sent from the methane fermentation tank 11 into the aerobic culture tank 21 is one amount of organic waste supplied to the methane fermentation tank 11 per unit time, and methane per unit time. It is desirable that it is 1 to 10% with respect to the methane fermenter supply / discharge amount which is 2 amount of methane fermentation liquid discharged from the fermenter 11.

  The aerobic fermenter 21 includes an aeration device 24 and a stirrer 25, and is configured to ensure aerobic conditions by being agitated under open air while performing aeration. Furthermore, it is preferable that the culture solution 3 is circulated in the aerobic culture tank 21 by a pump (not shown). The aeration conditions, the stirring speed, the circulation speed of the culture solution, and the like are determined by the volume of the culture tank 21 and the culture temperature.

  A nutrient source 4 suitable for the growth of aerobic bacteria is added to the aerobic culture tank 21 to which the methane fermentation liquid 2 is supplied from the methane fermentation tank 11, and the aerobic bacteria are cultured under the aerobic condition. Is done. Examples of the nutrient source 4 include polysaccharides such as starch, higher fatty acids such as stearic acid, monosaccharides such as glucose, disaccharides such as sucrose, amino acids such as glycine, and fats and oils such as stearic acid triglyceride. When at least one of these components is added to a concentration of 10 mg / liter or more with respect to the amount of the methane fermentation solution 2 sent from the methane fermentation tank 11, the necessary amount of the nutrient source can be satisfied. It is desirable to make it.

The temperature in the aerobic culture tank 21 is preferably substantially the same as the temperature in the methane fermentation tank 11, and the temperature of the culture solution 3 in the aerobic culture tank 21 is that of the methane fermentation solution 2 in the methane fermentation tank 11. It is preferable that the temperature is set within ± 5 ° C.
Further, the volume of the aerobic culture solution 21 is set so that the culture residence time in the aerobic culture tank 21 is 1 to 5 days.

  The culture solution 3 cultured for a predetermined time in the aerobic culture tank 21 is extracted from the culture solution outlet 23 of the aerobic fermentation tank 21, sent via the culture solution transfer line 30, and supplied to the culture solution supply port 15. Is returned to the methane fermentation tank 11.

  In actual operation of the methane fermentation system, the methane fermentation solution 2 is continuously supplied from the methane fermentation tank 11 to the aerobic culture tank 21 and the culture solution 3 in the aerobic culture tank 21 is preferred. It is continuously extracted from the aerobic culture tank 21 and returned to the methane fermentation tank 11 through the culture liquid transfer line 30 so that the methane fermentation liquid 3 and the culture liquid 2 are circulated.

The amount of the methane fermentation broth 2 supplied to the aerobic culture tank 21 is the same as the amount of the culture liquid 3 sent from the aerobic culture tank 21 to the methane fermentation tank. This is referred to as “supply discharge amount”.
The volume of the aerobic culture tank 21 is set according to the culture residence time in the aerobic culture tank 21 such that the aerobic culture tank volume / aerobic culture tank supply / discharge amount = culture residence time. .

Next, the operation of the above embodiment will be described.
In the methane fermentation tank 11, methanogens that are anaerobic bacteria grow and methane fermentation is carried out. However, the methane fermentation liquid 2 in the methane fermentation tank 11 cannot grow under anaerobic conditions. There are aerobic bacteria.

  According to the present embodiment, the aerobic bacteria contained in the methane fermentation solution 2 in the methane fermentation tank 11 are transferred to the aerobic culture tank 21 and cultured under aerobic conditions. Aerobic bacteria grow and hydrolases are produced as they grow. The culture solution 3 in which the hydrolase is produced is returned again into the methane fermentation tank 11 and the produced hydrolase is supplied into the methane fermentation tank 11 so that the hydrolase is organic even under anaerobic conditions. In order to hydrolyze the waste 1, the hydrolysis of the organic waste 1 proceeds with the hydrolase in the methane fermentation tank 11, while the methane fermentation by the methane-producing bacteria proceeds to improve the methane fermentation efficiency. Can do.

Therefore, since it is not necessary to add an enzyme reagent to the methane fermentation tank 11, the maintenance cost for operating the methane fermentation system can be reduced.
Moreover, since it is not necessary to install a large solubilization processing tank for processing the whole amount of the organic waste 1 before supplying it to the methane fermentation tank 11, its introduction cost and maintenance cost are not required and it is economical. is there.

The amount of the methane fermentation liquid 2 sent from the methane fermentation tank 11 to the aerobic culture tank 21 is one amount of organic waste supplied to the methane fermentation tank 11 per unit time, and the methane fermentation tank per unit time. 11 to 10% of the methane fermenter supply / discharge amount, which is 2 amounts of methane fermentation liquid discharged from No. 11. Further, in the aerobic culture tank 21, a sufficient amount of hydrolase is generated to improve the methane fermentation efficiency in the methane fermentation tank 11 by the culture residence time for one day. When the culture residence time is 5 days, the amount of hydrolase produced is further increased, but the amount of the culture solution 3 retained in the aerobic culture tank 21 is also increased five times, and the aerobic culture tank 21 is enlarged. Therefore, it is desirable to set the upper limit to 5 days.
As a result, the aerobic culture tank 21 is smaller than the solubilization tank that processes the entire amount of the organic waste 1 supplied to the methane fermentation tank 11, and the introduction cost of the aerobic culture tank 21 is sufficient. And maintenance costs are kept low.

For example, in the methane fermentation tank 11 that performs high-temperature methane fermentation at 55 ° C., the volume of the methane fermentation tank 11 that is required when processing the organic waste 1 of 90 m ³ / day is 1350 m ³ . When a solubilization tank is provided as a pretreatment for methane fermentation, the solubilization tank requires approximately the same volume.
On the other hand, the volume of the aerobic culture tank 21 required for this example depends on the amount of the methane fermentation broth 2 sent from the methane fermentation tank 11 to the aerobic culture tank 21 and the culture residence time, but is 0.9 to 45 m ^3. The introduction cost and maintenance cost of the aerobic culture tank 21 are small and economical.

  In addition, since the aerobic condition in the aerobic culture tank 21 is configured to be ensured by aeration and mechanical agitation under open air, the aerobic bacteria can be changed by changing the aeration condition and the agitation speed. Can be adjusted to be optimal aerobic conditions for producing hydrolase. When the culture medium is circulated using a pump and air is taken in, the aerobic condition can also be adjusted by changing the circulation rate of the culture liquid.

  Moreover, since the temperature of the culture solution 3 in the aerobic culture tank 21 is set within ± 5 ° C. of the temperature of the methane fermentation solution 2 in the methane fermentation tank 11, the culture in the aerobic culture tank 21 is performed. The temperature change of the methane fermentation liquid 2 in the methane fermentation tank 11 due to the return of the liquid 3 into the methane fermentation tank 11 can be reduced.

[Example 2]
Another embodiment of the methane fermentation system according to the present invention will be described in detail with reference to FIG.

  In this embodiment, the culture solution 3 cultured for a predetermined time in the aerobic culture tank 21 is introduced from the aerobic fermentation tank 21 into the organic waste supply line 10 via the culture solution supply line 30, and organic The organic waste 1 is returned to the methane fermentation tank 11 from the organic waste supply port 12 for supplying the organic waste 1 to the methane fermentation tank 11.

  According to this embodiment, when the culture solution 3 is supplied to the methane fermenter 11, the culture solution 3 is introduced into the organic waste supply line 10 and supplied from the organic waste supply port 12, whereby methane There is no need to separately provide a culture solution supply port in the fermenter 11 and no design change of the methane fermenter 11 is required. Other configurations are the same as those in the first embodiment.

[Other embodiments]
In order to investigate the methane fermentation efficiency when the culture solution obtained by culturing the methane fermentation broth under an aerobic condition was added to the methane fermentation tank, a methane fermentation test by a batch method was performed. FIG. 5 is a schematic configuration diagram of the methane fermentation tank used in the methane fermentation test.

An inlet 55 is provided in the center of the test methane fermentation tank 51, and the organic waste 54 is introduced from the inlet 55. After the introduction of the organic waste 54, the input port 55 is provided with an input port cap 56 to block air from entering and exiting, and the inside of the test methane fermentation tank 51 is in an anaerobic condition. Further, the stirring handle 58 is rotated to rotate the stirring paddle 57 so that the methane fermentation liquid 53 can be stirred. The test methane fermentation tank 51 is maintained at a constant temperature by a constant temperature water tank 52. The capacity of the methane fermentation tank 51 is 10 liters.
The amount of biogas 60 generated by methane fermentation in the test methane fermenter 51 is measured by a wet gas meter 59.

  The methane fermentation test 1 which set the temperature of the methane fermentation tank to 55 degreeC which is high temperature methane fermentation, and the methane fermentation test 2 which set to 37 degreeC which is medium temperature methane fermentation were performed.

[Methane fermentation test 1]
The conditions of the methane fermentation tank in the methane fermentation test 1 are shown below.
Methane fermentation temperature: 55 ° C (high temperature methane fermentation)
Organic waste volume: 700ml (milking cow manure)
Methane fermentation liquid volume: 10 liters The methane fermentation liquid 53 was extracted from the test methane fermentation tank 51, and the extracted methane fermentation liquid 61 was cultured under aerobic conditions for 1 day. As an aerobic culture tank, a beaker having a volume of about 10 to 20 times the amount of the extracted methane fermentation broth 61 was used, and stirred with a stirrer in an open atmosphere. Since this test is a small scale, aerobic conditions sufficient for the growth of aerobic bacteria can be obtained only by stirring with a stir bar, and thus aeration with an aeration apparatus was not performed. As a nutrient source for aerobic bacteria, starch, which is a polysaccharide, was extracted and added to the methane fermentation broth (culture liquid) at 100 mg / liter.

  Table 1 shows the amount of the extracted methane fermentation liquid extracted from the methane fermentation tank in this test. The extracted methane fermentation liquid amount / methane fermenter supply / discharge amount (%) described in Table 1 is the ratio of the amount of fermentation liquid extracted from the methane fermentation tank to the amount of organic waste charged into the methane fermentation tank. Since this test is performed by a batch method, the “amount of organic waste input to the methane fermenter” was calculated as the “methane fermenter supply / discharge amount”.

  Moreover, as a comparative example, the test of what is not added to a methane fermenter (Comparative Example 1) and the case where a hydrolase (COWATEC: MethaPlus 1,000) is added (Comparative Example 2 to Comparative Example 4) went. Table 2 shows the amount of hydrolase added in the comparative example.

メタン発酵槽から抜き出した抜出メタン発酵液６１を好気性条件下で1日間培養した培養液の全量を、再びメタン発酵槽に戻し、発生するバイオガスを測定した。図３は、メタン発酵試験１における発生バイオガス積算量とバイオガス発生速度の関係を示す図である。

The whole amount of the culture solution obtained by culturing the extracted methane fermentation solution 61 extracted from the methane fermentation tank for 1 day under aerobic conditions was returned to the methane fermentation tank, and the generated biogas was measured. FIG. 3 is a diagram showing the relationship between the generated biogas integrated amount and the biogas generation rate in the methane fermentation test 1.

  When 1 g of hydrolase is added (Comparative Example 2), the methane fermentation efficiency is almost the same as when no hydrolase is added (Comparative Example 1), and it can be said that there is no effect. When 10 g of hydrolase is added (Comparative Example 3), the biogas generation rate is increased and the methane fermentation efficiency is improved. When the amount of hydrolase (20 g) twice that of Comparative Example 3 was added (Comparative Example 4), the biogas generation rate was higher than that of Comparative Example 1, but was proportional to the increase in the amount added. The effect was not obtained.

Next, the methane fermentation broth was extracted from the methane fermenter, a nutrient source was added to the fermented broth, and the culture broth cultured for one day under aerobic conditions was returned to the methane fermenter to perform methane fermentation. Example 4 will be described.
The biogas generation rate of Example 1 from which 0.7% of the organic waste amount of methane fermentation liquid was extracted was almost the same as that of Comparative Example 1, and the effect of improving methane fermentation efficiency was not obtained. Example 2 which extracted 1.0% of methane fermentation liquid of the amount of toxic waste is the improvement effect of the methane fermentation efficiency equivalent to the comparative example 3 which added hydrolase 10g, and the comparative example 4 which added hydrolase 20g. Is obtained. Example 3 and Example 4 which increased the extraction amount of the methane fermentation broth are more effective than Example 2 because the biogas generation rate is further increased.

  In the case of high-temperature methane fermentation where the fermentation temperature of the methane fermenter is 55 ° C, 1.0% or more of the methane fermentation broth is extracted with respect to the amount of the organic waste added, and the nutrient source is provided under aerobic conditions. By culturing, the methane fermentation efficiency could be improved more than the effect of adding hydrolase.

[Methane fermentation test 2]
About the case where the fermentation temperature of a methane fermentation tank is 37 degreeC, the methane fermentation test using the test methane fermentation tank was done similarly to the methane fermentation test 1. FIG. The conditions of the methane fermentation tank in the methane fermentation test 2 are shown below.
Methane fermentation temperature: 37 ° C (medium temperature methane fermentation)
Organic waste volume: 300ml (milking cow manure)
The amount of methane fermentation broth: 10 liters The methane fermentation broth was extracted from the methane fermentation tank, cultured in an aerobic culture tank, returned to the methane fermentation tank, and the test method for measuring the generated biogas is the methane fermentation test 1 Since this is the same, the description thereof is omitted.

Table 3 shows the amount of the extracted methane fermentation liquid extracted from the methane fermentation tank in this test. The explanation of the extracted methane fermentation liquid amount / methane fermenter supply / discharge amount (%) described in Table 3 is the same as in the methane fermentation test 1 and is omitted here.
Moreover, as a comparative example, a test was carried out on a sample not added to the methane fermenter (Comparative Example 5) and a case where a hydrolase (COWATEC: MethaPlus 1,000) was added (Comparative Example 6). Table 4 shows the amount of hydrolase added in the comparative example.

図４は、メタン発酵試験２における発生バイオガス積算量とバイオガス発生速度の関係を示す図である。
投入した有機性廃棄物量の０．３％のメタン発酵液を抜き出した実施例５のバイオガス発生速度は、比較例５とほとんど変わらず、メタン発酵効率向上の効果は得られなかったが、投入した有機性廃棄物量の１．０％のメタン発酵液を抜き出した実施例６は、加水分解酵素１０ｇを加えた比較例６よりもメタン発酵効率は向上している。メタン発酵液の抜き出し量を増やした実施例７および実施例８は、実施例５よりも更にバイオガス発生速度が上がり、より効果的である。

FIG. 4 is a diagram showing the relationship between the generated biogas integrated amount and the biogas generation rate in the methane fermentation test 2.
The biogas generation rate of Example 5, which extracted 0.3% of the methane fermentation liquid of the amount of the organic waste input, was almost the same as that of Comparative Example 5, and the effect of improving the methane fermentation efficiency was not obtained. Example 6 which extracted 1.0% of methane fermentation liquid of the amount of the organic waste which performed did methane fermentation efficiency is improving rather than the comparative example 6 which added hydrolase 10g. Example 7 and Example 8 which increased the extraction amount of the methane fermentation broth are more effective than Example 5 because the biogas generation rate is further increased.

  In the case of mesophilic methane fermentation where the fermentation temperature of the methane fermenter is 37 ° C., 1.0% or more of the methane fermentation broth is extracted with respect to the amount of organic waste added, and a nutrient source is provided to provide aerobic conditions. By culturing below, the methane fermentation efficiency could be improved more than the effect of adding hydrolase.

  In addition, in the methane fermentation test 1 and the methane fermentation test 2, the nutrient source of the aerobic bacteria used polysaccharides starch, but higher fatty acids such as stearic acid, monosaccharides such as glucose, disaccharides such as sucrose, Tests have shown that similar results can be obtained by adding amino acids such as glycine and fats and oils such as stearic acid triglyceride as nutrient sources.

  The present invention is applicable to a methane fermentation system and method for methane fermentation of organic waste in a methane fermenter.

It is a schematic structure figure showing one example of a methane fermentation system concerning the present invention. It is a schematic block diagram which shows the other Example of the methane fermentation system which concerns on this invention. It is a figure which shows the relationship between the amount of generation | occurrence | production biogas in the methane fermentation test 1 (high temperature methane fermentation), and biogas generation | occurence | production speed | velocity. It is a figure which shows the relationship between the amount of generation | occurrence | production biogas in the methane fermentation test 2 (medium temperature methane fermentation), and biogas generation | occurence | production speed | velocity. It is a schematic block diagram of the methane fermentation tank used for the methane fermentation test.

Explanation of symbols

1 organic waste, 2 methane fermentation broth, 3 culture broth,
4 nutrient sources, 5 air,
10 Organic waste supply line,
11 Methane fermentation tank, 12 Organic waste supply port,
13 Methane fermentation liquid outlet, 14 Methane fermentation liquid outlet,
20 Methane fermentation broth transfer line,
21 aerobic culture tank, 22 methane fermentation broth supply port, 23 culture broth outlet,
24 aeration device, 25 stirrer,
30 culture fluid transfer line,
41 grinding machine, 42 slurry tank, 43 biogas 51 methane fermentation tank for testing, 52 thermostatic water tank, 53 methane fermentation liquid,
54 organic waste, 55 inlet, 56 inlet cap,
57 Stir paddle, 58 Sales handle, 59 Wet gas meter,
60 Biogas 61 Extracted methane fermentation liquor

Claims (6)

A methane fermentation tank for methane fermentation of organic waste under anaerobic conditions, and a part of the methane fermentation liquid in the methane fermentation tank and a nutrient source are sent to aerobic bacteria contained in the methane fermentation liquid. An aerobic culture tank for producing a hydrolase in the culture medium by culturing under aerobic conditions,
As the nutrient source, at least oils and fats are added so as to have a concentration of 10 mg / liter or more with respect to the amount of the methane fermentation solution sent from the methane fermentation tank ,
A methane fermentation system, wherein a culture solution in which a hydrolase is generated in the aerobic culture tank is returned to the methane fermentation tank.   The amount of organic waste supplied to the methane fermenter per unit time in claim 1 and 1 of the methane fermenter supply / discharge amount that is the amount of methane fermentation liquid discharged from the methane fermenter per unit time A methane fermentation system configured to send a methane fermentation solution having an amount of 10% to 10% from a methane fermentation tank to an aerobic culture tank.   The methane fermentation system according to claim 1 or 2, wherein a culture residence time in the aerobic culture tank is 1 to 5 days.   The aerobic condition in the aerobic culture tank according to any one of claims 1 to 3 is ensured by aeration, mechanical agitation in an open atmosphere, and / or culture medium circulation by a pump. Methane fermentation system. In any one of claims 1 to 4, wherein the methane, characterized in that the temperature of the culture of aerobic fermenter is set within ± 5 ℃ temperature methane fermentation liquid in the methane fermentation tank Fermentation system. Part of the methane fermentation liquid in the methane fermentation tank for methane fermentation of organic waste, and at least oils and fats as the nutrient source, 10 mg / liter with respect to the amount of the methane fermentation liquid sent from the methane fermentation tank The aerobic culture tank is sent to an aerobic culture tank so as to have the above concentration, and the aerobic bacteria contained in the methane fermentation broth are cultured under aerobic conditions in the aerobic culture tank and hydrolase is contained in the culture liquid. Then, the culture broth produced by the hydrolase is returned to the methane fermentation tank.

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