KR100883676B1 - Apparatus for the two phase anaerobicdigestion - Google Patents

Abstract

An apparatus for two phase anaerobic digestion controlling pH by monitoring the pH in real-time is provided to prevent decrease of the pH generated by installing a buffer reactor between an acid fermentation tank and a methane fermentation tank and flowing in an acid fermentation liquid flown from the acid fermentation tank to the methane fermentation tank. An apparatus for two phase anaerobic digestion controlling pH by monitoring the pH in real-time contains a raw material storage tank(1), an acid fermentation tank(2) in which acid is fermented, a methane fermentation tank(4) in which methane is fermented and a gas collection unit(5). A buffer tank is additionally equipped between the acid fermentation tank and the methane fermentation tank. PH sensors for measurement are installed at the acid fermentation tank, the methane fermentation tank and the buffer tank. A lime tank is connected to the buffer tank. The pH of the acid fermentation tank is 5 to 6.

Description

ABAPATUS FOR THE TWO PHASE ANAEROBICDIGESTION with pH control through real-time pH monitoring

The present invention relates to an abnormal anaerobic digestion apparatus for treating organic waste, and more specifically, to prevent the pH decrease caused by the acid fermentation liquid flowing out of the acid fermentation tank directly into the methane fermentation tank, Introduces a controllable buffer tank, and each reactor is equipped with a sensor to measure pH, so that pH monitoring can be performed in real time to respond promptly and promptly when an impact load is issued in each reactor. The present invention relates to an abnormal anaerobic digestion apparatus in which pH control is performed through real-time pH monitoring to maximize and stabilize biogas generation.

Looking at the current status of food waste disposal in Korea, compared to the past, the direct and landfill prohibition provisions of food waste were specified in the Waste Management Act, and the ban on wet garbage was put in the metropolitan landfill, and local governments separated the apartments. The collection rate was gradually increased and the amount of landfill was decreased. In other words, landfilling accounted for more than 92.8% of the total landfill land until 1996, but since then, it has continued to decline, reaching 24.88% in 2003. In addition, the recycling rate of food waste increased slightly from 2.1% in 1995, but the recycling rate increased to 67.71% for all food waste generated in 2003. As each municipality is expanding the separate collection to single-family homes, the resource rate will be higher.

As part of the process of recycling food waste as described above, the research on the recycling of food waste with methane gas, that is, research on anaerobic digestion, is being actively conducted.

Anaerobic digestion is the process by which many complex symbiotic microbial communities decompose organic matter into methane and carbon dioxide in the absence of oxygen. Theoretically, about 90% of the biodegradable organics in the waste can be converted to methane, and moreover, the sludge produced after the anaerobic digestion by stabilizing the organic wastes does not cause any environmental hazards to the soil and water, so that the soil improver and fertilizer It can be used as a further energy savings.

In particular, methane, the main component of biogas, is a flexible form of renewable energy, which can be converted into heat and electricity, and used as a vehicle fuel.

After all, anaerobic digestion reduces the potential risk to global climate change in two ways. First, by capturing biogas through anaerobic digestion, it is possible to reduce methane emissions in the natural state. Methane, which has about 21 times more global warming than carbon dioxide, accounts for about 15% of greenhouse gas emissions in Korea. Second, if biogas produced in anaerobic digestion can be replaced with fossil fuels, carbon dioxide generated from chemical fuels can be avoided, thereby reducing global warming agents.

However, the anaerobic digestion process has problems such as low growth rate of microorganisms, odor problems of treated effluents, and the need for a large amount of buffer for pH control. It is difficult to overcome these problems with the existing technology, which is not attracting much attention compared to the aerobic treatment process.

This is because monitoring and control of successful anaerobic process operations is relatively difficult because different species of anaerobic bacteria form a symbiotic relationship and the conversion of various organic substances to methane is very complicated and requires multiple steps.

In addition, in the single-phase fire extinguishing system applied to sewage sludge treatment, an acid fermentation step and a methane fermentation step are performed in one reactor. Although acid fermentation microorganisms and methane fermentation microorganisms are symbiotic, the optimum growth conditions are different from each other, so the application of a single-phase digester is not a big problem for sewage sludge with uniform properties and relatively low organic content. However, application of single-phase digester to high concentration of organic matter and un homogenized food waste or livestock manure leads to excessive VFA (volatile fatty acid) production, causing problems such as pH drop.

In order to supplement these problems and to ensure stable operation of the system, the application of a two-phase anaerobic digestion facility that separates an acid fermentation tank and a methane fermentation tank has been attempted.

However, since the advantages microorganisms of each reactor are very different and the operating conditions are different, the operation strategy for setting and maintaining the optimum conditions is still insufficient. In particular, the best pH for fermentation in a methane fermentation tank is 7.0, but the acid generated from the acid fermenter enters the fermenter directly and acid shock occurs, resulting in a case where the operation of the process itself is stopped. do.

Prior arts proposed to solve the above problems are published in Korean Patent Publication No. 1995-0017748 (1995.07.20), "Method for treating high concentration organic wastewater by abnormal digestion using a membrane" and Patent No. 352811 (2002.09.02) Fast digestion of food waste and methane production method using stage methane fermentation system.

First of all, Korean Patent No. 195-0017748 adopts a two-phase anaerobic digestion system that separates an acid fermentation process and a methane fermentation process, but installs a membrane in between the two phases to lower the organic load of the methane fermentation process, and methane fermentation process. It is characterized in that the use of activated carbon as a filler to maintain the density of the bacteria,

The membrane disclosed in the above-mentioned Patent Publication No. 195-0017748 is not intended for the pH control function required for the methane fermentation process later, but merely serves to filter the digestion from the acid fermentation process. It is not a configuration that can complement the limitations.

Next, Patent No. 352811 is mixing food waste, which is pulverized into small particles in a crusher, in a 1: 1 ratio with water, transporting it to a first semi-anaerobic hydrolysis and acid fermenter through a screw, and injecting air with an air injection pump. Hydrolyzed at high speed by aerobic bacterial preparations in combination with Cellulomonas cellulose, Flavobacterium bribes, Bacillus amyloliquefaciens, Bacillus richenomyces, Bacillus subtilis, Bacillus alkalophilus The first semi-anaerobic hydrolysis and acid fermentation process for acid fermentation by anaerobic bacteria, and the first fermented solid-liquid component are injected through a lower portion of the second anaerobic acid fermenter in the form of an upstream anaerobic sludge blanket by a pump, and the Clostridium booti Second anaerobic acid fermentation step of acid fermentation by recombination with licom, and only liquid components of the second liquid fermentation That comes down through the intermediate tube to the top of the hyojo transported by a metering pump in a tertiary methane fermenter was inoculated and the methanogens consisting of tertiary methane fermentation step to produce methane and technically characterized in that

As a result, the Patent No. 352811 discloses a three-stage fermentation system by discarding the existing two-phase anaerobic digestion process and introducing a hydrolysis stage before the acid fermentation process, which solves the problem in the two-phase anaerobic digestion process itself and provides an optimum effect. Not only contradicts the basic purpose of the invention

Even if the vehicle operates under the conditions described above, the problem of remaining inevitably has to meet the limit point in adjusting the pH introduced into the methane fermentation tank.

In addition to the above-described prior art, Korean Patent Publication No. 10-2005-0097048 (2005.10.07) discloses a method for treating organic waste using a continuous batch high temperature / medium temperature two-stage anaerobic digestion process, but this configuration is also intended to be implemented in the present invention. Is different.

The present invention has been made to solve the above problems of the prior art, while maintaining the two-phase anaerobic digestion method, introducing a buffer tank to prevent the pH drop of the methane fermentation tank by the acid fermentation solution flowing out of the acid fermentation tank In addition, each reactor is equipped with a pH measuring sensor and a line tank that can adjust the pH of the buffer tank to the buffer tank to the ideal anaerobic digestion apparatus that can maintain the best microbial activity conditions for each reactor including the methane fermentation tank For the purpose of providing

In the end, it aims to provide an anaerobic digestion apparatus that can be expected to improve energy yield through maximizing biogas generation and maximizing methane yield.

Abnormal anaerobic digestion apparatus is a pH control through the real-time pH monitoring of the present invention for achieving the above object, the raw material storage tank in which the treatment object is stored, and the acid fermentation tank made of acid fermentation of the treatment object flowing from the raw material storage tank, Formed in a separate space from the acid fermentation tank is made of a methane fermentation tank in which the fermentation broth of the acid fermentation tank is introduced into the methane fermentation, and a gas collecting device for collecting the gas of the fermentation broth methane fermentation in the methane fermentation tank,

A buffer tank is further provided between the acid fermentation tank and the methane fermentation tank so that the fermentation broth of the acid fermentation tank is introduced into the methane fermentation tank after passing through the buffer tank.

The acid fermentation tank or the methane fermentation tank or the buffer tank or both of them is provided with a sensor for pH measurement, the sensor is characterized in that the monitoring of the pH value of each reaction tank to be connected to the external monitor.

In addition, the buffer tank of the abnormal anaerobic digestion apparatus according to the present invention is connected to the lime tank for lime injection to adjust the pH value in the buffer tank,

The pH of the buffer tank is characterized in that to maintain 7 or more.

In the abnormal anaerobic digestion apparatus according to the present invention, the pH of the acid fermentation tank is 5 to 6, and the pH of the methane fermentation tank is 6.5 to 8.

The present invention maintains the existing two-phase anaerobic digestion method, but further provided with a buffer tank between the acid fermentation tank and the methane fermentation tank to prevent the pH decrease caused by the acid fermentation solution flowing out of the acid fermentation tank immediately flow into the methane fermentation tank Not only can it keep the methane fermentation tank in the best working condition

In particular, acid fermentation tanks, methane fermentation tanks, and sensors for measuring the pH of the buffer tanks are attached and monitored in real time to control the pH of the buffer tanks. The effect of maximizing and stabilizing biogas generation can be obtained.

Hereinafter, a specific configuration and operation manner of the present invention will be described with reference to the drawings.

In addition, hereinafter, the term "reactor" should be used when referring to more than one raw material storage tank, acid fermentation tank, methane fermentation tank, and buffer tank.

As mentioned above, in the conventional single-phase digestion method, acid-forming bacteria and methane-forming bacteria were operated in one reactor, in which case the rate of methane production of methane-producing bacteria was relatively slower than that of acid-forming bacteria. Eventually results in the accumulation of VFAs (volatile fatty acids).

This causes a drop in pH and inhibits the activity of methane forming bacteria. Moreover, acid-forming and methane-forming bacteria differ greatly in their physiological properties, nutritional requirements, growth kinetics, and sensitivity to their environment.

For this reason, a two-phase anaerobic digester has been developed. In the existing two-phase anaerobic digester, the growth of microorganisms in each reactor, such as failure to adjust the pH of each reactor, is inhibited. This may cause acid formation to be inhibited, lower the efficiency of biogas (methane) generation, and also remain a problem of not responding to sudden load stratification.

Therefore, in the present invention, as shown in Figure 1, while introducing the anaerobic digestion apparatus as it is, to adjust the pH concentration of the acid fermentation solution flowing out of the acid fermentation tank (2) between the acid fermentation tank (2) and methane fermentation tank (4) It is further provided with a buffer tank 3 that can function.

The pH of the buffer tank (3) is formed to maintain a pH of 6.8 to 7.2 so that the function of increasing the pH of the acid fermentation solution to be introduced into the methane fermentation tank.

Moreover, it is preferable that the more preferable pH of the buffer tank 3 is maintained at 7.

That is, the abnormal anaerobic digestion apparatus according to the present invention comprises a raw material storage tank (1) in which a treatment target is stored, an acid fermentation tank (2) in which acid fermentation of the treatment target flowing from the raw material storage tank is performed, and a separate space from the acid fermentation tank. The fermentation broth of the acid fermentation tank is introduced into the methane fermentation tank 4 and methane fermentation is provided between the acid fermentation tank and the fermentation broth of the acid fermentation tank, which is provided between the acid fermentation tank and the methane fermentation tank, and then the buffer tank for inputting the methane fermentation tank (3) and a gas collecting device 5 for collecting the gas of the fermentation broth from which the methane fermentation has been performed in the methane fermentation tank.

Further, the lime tank 6 is connected to the buffer tank 3, which is supplied with lime from the lime tank 6 when it is necessary to increase the pH in the buffer according to the pH measurement value of the buffer tank. This is to adjust the pH of the tank (3) to maintain the optimum pH for the active operation of the methane fermentation tank (4) connected thereto.

The reagent flowing into the buffer tank 3 from the lime tank 6 is preferably lime, but may be sodium hydroxide (NaOH).

Next, the containers of the raw material storage tank (1), acid fermentation tank (2), buffer tank (3), and methane fermentation tank (4) are made of 5L, 20L, 500mL, 25L, respectively, and the material is made of acrylic. do.

Each reactor was equipped with a water jacket to maintain the temperature. In the case of the raw material storage tank (1), it is preferable to suppress the reaction of the microorganisms in the storage tank, so that the internal temperature is set to 2 ° C to 6 ° C using the cooler (R). Maintained at ° C.,

Acid fermentation tank (2) and methane fermentation tank (4) was maintained at 32 ℃ to 38 ℃ by installing a thermostat,

More preferably, in the case of the raw material storage tank 1, the temperature is maintained at 35 ° C in the case of the acid fermentation tank 2 and the methane fermentation tank 4.

In addition, a stirrer (A) is installed in the raw material storage (1), acid fermentation tank (2), and methane fermentation tank (4) so that reaction occurs well in each reaction tank, and a magnetic stirring device (A ') is installed in the buffer tank (3). to do,

In the case of the acid fermentation tank (2) and the methane fermentation tank (4), it is preferable to use a motor type stirrer because the capacity of the agitating liquid is large, and in the case of the buffer tank (3), the capacity is smaller than that of the acid fermentation tank and the methane fermentation tank. This is because it is preferable to provide a magnetic stirrer for stirring while the bar rotates.

The gas collecting device collects the gas generated by using a level displacement gas collecting device. The water leveling gas collecting device is prepared by saturating with sodium chloride and adding sulfuric acid.

In addition, the outflow and inflow in each reactor are allowed to be continuously injected using a metering pump. Particularly, in the case of the raw material storage tank 1, the raw material inlet is packed with a rubber stopper to prevent air from entering the acid fermentation tank during the raw material injection, and a gas bag (B) purged with nitrogen gas is attached to the outer circumferential surface of the raw material storage tank to prepare for negative pressure. It is desirable to.

As an example of the anaerobic microorganism of the present invention, the acid-fermenting microorganism may be acetobacter species, lactobacillus sp., Streptococcus speices, pediococcus sp. Any one or two or more selected from microorganisms such as onibacterium spisis (propionibacterium species) can be used,

Methane-producing microorganisms have been studied in a relatively detailed manner, including: metanobacterium spp., Metanobrevibacter spp., Metanospririllum spp. Methanoplanus species, methanococcus species, methanosarcina species, methanosarcina species, methanothrix species, methanothrix species, methanolobus species, meta Any one or more than one selected from the method (methanococcoides species) can be used,

Acid fermentation tanks and methane fermentation tanks with effective volumes of 8 L and 22 L, respectively, are inoculated with sludge from acid fermentation tanks and methane fermentation tanks anaerobicly digesting food waste and livestock manure (money). However, the inoculated sludge of the acid fermentation tank is heat treated at 92 ° C to 98 ° C for 13 to 17 minutes to achieve the preponderance of hydrogen producing bacteria that form spores, and to allow the methane producing bacteria to be killed. It is preferable to heat-process for 15 minutes at 95 degreeC with respect to the inoculation sludge of the.

Initially after sludge inoculation, the inoculated microorganisms were acclimated to operate, and the HRT (hydraulic retention time, hydraulic retention time) of acid fermentation tank (2) and methane fermentation tank (4) was respectively measured. Set to 3 days and 9 days according to the growth rate to operate continuously.

This is because when the raw material injection is intermittent, it may negatively affect the germination of spore forming bacteria responsible for hydrogen generation.

In addition, pH is a factor that greatly affects the growth of microorganisms in acid fermentation tanks and methane fermentation tanks, and the optimum pH for growth of microorganisms in acid fermentation tanks and methane fermentation tanks is different.

Therefore, in the case of acid fermentation tank (2) pH is set to about 5 to 6, in the case of methane fermentation tank (4) it is preferable to adjust the pH to about 6.5 to 8, methane fermentation tank is to operate at pH 7. In particular, methane-producing bacteria are very sensitive to change and are difficult to grow when the pH drops below 6 due to the accumulation of organic acids.

Moreover, in the present invention, the pH can be buffered between the acid fermentation tank and the methane fermentation tank. Will reduce the effect on the methane fermentation tank (4).

Furthermore, in the anaerobic digestion apparatus of the present invention, it is possible to control the pH by monitoring the pH in real time.

That is, each acid fermentation tank (2), methane fermentation tank (4) and buffer tank (3) is installed a pH sensor, ORP sensor, and temperature sensor (S) and directly connected to the DAC (Date Acquisition and Control) device Continuously monitor whether the pH and temperature of each reactor is maintained within a certain range through an external monitor (M).

More specifically, data collected from the pH sensor installed in each reactor are collected from DAQ (Date Acquisition), and the collected data is continuously monitored by the Labview program.

Eventually, the pH change in the buffer tank 3 is monitored by the Labview program. When the pH value is lowered below a certain value that can affect the operation of the connected methane fermentation tank 4, that is, below pH 6.8. When the pump connected to the lime tank 6 is turned on to adjust the pH, lime (Caime) is automatically injected into the buffer tank 3.

After the lime is injected, when the pH of the buffer tank 3 recovers to about 7, the lime injection is stopped. As a result, the pH of the buffer tank 3 is adjusted to overcome the phenomenon of inhibiting methane production by the pH decrease from the methane fermentation tank 4.

Next, the object to be treated that is introduced into the raw material storage tank 1, that is, organic waste is preferably composed of food waste and livestock manure or food waste and sewage sludge or food waste and livestock manure and sewage sludge.

In other words, by diluting the high concentration of salt, which is a disadvantage of food waste, and providing the high content of organic matter to other sewage sludge or livestock manure, biogas recovery can be increased and high quality by-product compost can be produced.

In particular, the mixing ratio of food waste is preferably 1: 1 when combining food waste with livestock manure, and combining food waste with sewage sludge, and 2: 1: 1 when combining food waste with livestock manure and sewage sludge. Do. The mixing ratio was calculated through a batch methane production capacity evaluation (BMP Test).

Hereinafter, using the anaerobic digestion apparatus of the present invention, an experiment for examining the pH and biogas generation amount generated during the treatment of food waste and livestock manure, food waste and sewage sludge, and organic waste mixed with food waste and livestock fermentation and sewage sludge It is content.

end. Food waste and livestock manure

The optimal mixing ratio of food waste and pig manure was 1: 1 (food waste / pig manure) and operated for 100 days. Food wastes were taken from the food waste recycling facility, and pig manure was taken from a nearby pig house.

1) pH

Table 1-1 below shows the results of monitoring the pH of raw material storage tank, acid fermentation tank and methane fermentation tank for 200 days. The pH of the injected raw materials varied from 4.7 to 6.7 with an average pH of 5.5. In the case of acid fermentation tank, the pH was increased to 6.3 as the stabilization stage until 20 days of operation, but it was confirmed that the pH was maintained within the proper pH 5 ~ 6 range of the acid fermentation tank with an average pH of 5.8 between pH 5.6 ~ 6.2. Despite the effects of organic acids and carbon dioxide generated during the fermentation of raw materials, the pH of the acid fermentation tank was determined to be relatively stable due to the buffering effect of the combined digested pig meal.

The methane fermenter also stabilized after 20 days, with a pH of at least 7.7, a maximum of 8.0, and an average pH of 7.9. This is slightly higher than the pH range of 7 to 7.5, but within the proper pH range of 6.5 to 8.0 of the anaerobic digestion process, it is considered that there is no pH inhibitory effect on the methane fermentation.

Table 1-1

PH change during operation

2) Biogas Generation

Table 1-2 below shows the gas generation amount measured during the operation period of about 200 days. In the case of acid fermenters, the gas generation during the initial 20 days was insignificant, but after 20 days, the generation started to increase, and the average was 6.0 L / d until 58 days before the organic load of the raw material began to decrease. Thereafter an average of 1.3 L / d of biogas was generated.

Methane fermenters also stabilized 20 days after the start of operation, with biogas of 44 and 25 L / d on average for 58 days. As the organic load was lowered, the amount of generated gas rapidly decreased in the case of the acid generating tank, but gradually decreased in the case of the generating gas of the methane generating tank.

Table 1-2

-Changes in gas generation in acid fermentation tanks (left) and methane fermentation tanks (right) during operation

I. Food Waste and Sewage Sludge

The optimum mixing ratio of food waste and sewage sludge was 1: 1 (food waste / sewage sludge) and operated for 100 days. Food wastes were used for the desorption liquid of the food waste recycling facility, and sewage sludge was used for the concentrated sludge of the sewage treatment plant operated by the standard activated sludge process.

1) pH

Table 2-1 shows the results of monitoring the pH of raw material storage tank, acid fermentation tank and methane fermentation tank for 100 days. The pH of the injected raw materials was maintained at pH 4.0 ~ 6.6 except for shock loading. The pH of the acid fermentation tank was greatly affected by the change of raw materials and maintained between pH 4.5 and 5.8. The methane fermentation tank maintained a pH above 7.5 regardless of the pH change of the incoming raw material, which is due to the pH control of the buffer tank.

Table 2-1

PH change during operation

2) Biogas Generation

Table 2-2 shows the biogas generation and composition change in the acid fermentation tank during the operation period. The acid fermentation tank also produced a great change in gas generation as the substrates were introduced. Most of the biogas produced was CO ₂ , and CH ₄ was less than 20%.

Table 2-2

Changes in gas generation and composition in acid fermentation tanks during operation

Table 2-3 shows changes in biogas generation and composition in the methane fermentation tank during the operation period. After the initial 20-day stabilization period, an average of 13.9 L / d of biogas was generated, of which about 69% was methane. The methane gas composition remained above 60% during operation. In spite of the poor loading of the incoming substrate, the methane fermentation tank showed stable biogas generation.

Table 2-3

-Changes in gas generation and composition in the methane fermentation tank during operation

All. Food Waste, Livestock Manure and Sewage Sludge

The substrates of abnormal anaerobic digestion were subjected to food waste, livestock manure and sewage sludge for an optimal mixing ratio of 2: 1: 1 (food waste / dung manure / sewage sludge) for 100 days. Food wastes were taken from the food waste recycling facility's desorption solution, and pig manure was used from the nearby pig sand and sewage sludge, using the concentrated sludge from the sewage treatment plant operated by the standard activated sludge process.

1) pH

Table 3-1 shows the pH change of each reactor during the operation period for 100 days. The pH of the incoming raw material storage tank was changed from 4.2 to 6.5, and the pH of the acid fermentation tank showed the same trend as the incoming raw material storage tank and maintained at pH 4.5 to 6.5. However, in the case of the methane fermenter was pH controlled in the buffer tank was maintained in a favorable condition for methane production above pH 7.5. This indicates that the condition of pH, which is a major environmental factor of the anaerobic digestion process, is suitable for the growth of microorganisms in the methane reactor.

Table 3-1

PH change during operation

2) Biogas Generation

Table 3-2 shows the changes in biogas generation and composition in the acid fermentation tank during 100 days of operation. Biogas generated from the acid fermentation tank produced 5.5 L / d on average, about 61% CO ₂ and 16 CH ₄ . In particular, 10 to 20% of the generated biogas is H ₂ . The generation of hydrogen appeared intermittently. This is because hydrogen-producing microorganisms are sensitive to pH, and hydrogen production may be limited when the proper environment is not established. Therefore, if proper process control is performed in an acid fermentation tank, continuous hydrogen generation can be expected.

Table 3-2

-Gas generation and composition change in acid fermentation tank during operation period

Next, Table 3-3 shows biogas generation and composition in the methane fermentation tank during the 100-day operation period. In the methane fermentation tank, an average of 33.9 L / d of biogas was generated, and 71% of CH ₄ was generated. By controlling the pH in the buffer tank, the methane fermentation tank showed stable methane generation during the operation period. Therefore, if the unit is well stabilized, the methane fermentation can be produced continuously and with high yield in the anaerobic digestion process.

Table 3-3

-Changes in gas generation and composition in the methane fermentation tank during operation

1 is a schematic diagram of an abnormal anaerobic digestion apparatus according to the present invention.

* Explanation of symbols for the main parts of the drawings *

1: Raw material storage tank 2: Acid fermentation tank 3: Buffer tank 4: Methane fermentation tank

5: gas collector 6: lime tank

Claims (5)

A raw material storage tank in which an object to be treated is stored; An acid fermentation tank in which acid fermentation of the processing object flowing from the raw material storage tank is performed; A methane fermentation tank formed in a separate space from the acid fermentation tank, in which the fermentation broth of the acid fermentation tank is introduced to perform methane fermentation; And In the methane fermentation tank consists of a gas collecting device for collecting the gas of the fermentation broth made methane fermentation, A buffer tank is further provided between the acid fermentation tank and the methane fermentation tank, and the fermentation broth of the acid fermentation tank is introduced into the methane fermentation tank after the pH is adjusted while passing through the buffer tank. The acid fermentation tank or the methane fermentation tank or the buffer tank or both are provided with a sensor for pH measurement, the sensor is connected to an external monitor to monitor the pH value of each reactor, When the buffer tank is connected to the lime tank for lime injection, when the pH value measured by the pH measuring sensor installed in the buffer tank is less than 6.8, the lime is automatically injected into the buffer tank from the lime tank and the pH value of the buffer tank is 6.8. Abnormal anaerobic digestion apparatus made of pH control through real-time pH monitoring, characterized in that to maintain more than 7.2. delete delete The abnormal anaerobic digestion apparatus of claim 1, wherein the pH of the acid fermentation tank is adjusted to 5 to 6 by real-time pH monitoring. The abnormal anaerobic digestion apparatus of claim 1, wherein the pH of the methane fermentation tank is 6.5 to 8.

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