Construction method and device of normal temperature-medium temperature efficient two-phase anaerobic digestion system
By constructing a two-phase anaerobic system consisting of an ambient-temperature acid-producing phase and a mesophilic methanogenic phase, and enriching specific bacterial communities, the system instability problem of anaerobic digestion under high organic load and high ammonia nitrogen conditions was solved, achieving efficient and low-cost anaerobic digestion.
Patent Information
- Application Number
- CN202610147911.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-03
- Publication Date
- 2026-05-01
AI Technical Summary
Existing anaerobic digestion processes are prone to volatile fatty acid accumulation and system instability when treating wastes with high organic loads and high ammonia nitrogen levels, leading to unstable operation and limiting their application in practical engineering.
A two-phase anaerobic system consisting of an ambient-temperature acid-producing phase and a mesophilic methanogenic phase was constructed. By gradually introducing carbon sources such as glucose and sodium formate, homotrophic acetogenic bacteria and symbiotic acetoxygenating bacteria-hydrogen-producing bacteria were enriched, optimizing the system structure and avoiding the addition of additional inhibitors.
Stable operation of the system under high organic load and high ammonia nitrogen conditions has been achieved, reducing operating costs, avoiding the accumulation of volatile acids, and improving methane yield and energy utilization efficiency.
Smart Images
Figure CN121948689A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of rapeseed treatment technology, and in particular to a method and apparatus for constructing a high-efficiency two-phase anaerobic digestion system at ambient and mesophilic temperatures. Background Technology
[0002] With the continuous improvement of urban residents' living standards and the ongoing development of industry and agriculture, the output of organic waste has been rising steadily, seriously threatening the ecological environment and residents' health. Among these, approximately 1.3 billion tons of food waste (FW) are generated annually, placing enormous pressure on waste management and the environment. Studies have shown that the various components in food waste, such as lipids, proteins, and starches, are highly suitable for anaerobic digestion (AD) processes. Anaerobic processes are also commonly used for treating organic waste due to their ability to handle complex organic waste and recover energy (methanogenesis). However, when treating food waste, the high organic load and high levels of ammonia nitrogen released during anaerobic processes can lead to the accumulation of volatile fatty acids (VFAs) within the anaerobic system, resulting in instability and even system collapse.
[0003] Many studies have focused on improving methane yield and gas production in anaerobic processes for food waste treatment, such as the anaerobic co-digestion of food waste with municipal sludge or leachate. Municipal sludge can improve the C / N balance during digestion, promoting the operation of the anaerobic digestion system, while trace elements in leachate can enhance the activity of microorganisms in the anaerobic system. However, the anaerobic co-digestion of food waste with municipal sludge or leachate also suffers from operational instability and acid accumulation. Furthermore, some studies have shown that adding conductive materials (CMs) to anaerobic systems can promote methane yield by initiating direct electron transfer (DIET) between symbiotic acid-producing and methanogenic bacteria in the methanogenic system. However, the addition of CMs presents challenges such as high operating costs and secondary pollution.
[0004] To address the problems of volatile fatty acid (VFA) accumulation and high ammonia nitrogen inhibition that arise in existing anaerobic digestion processes when handling high-organic-load and high-ammonia-load organic waste, it is crucial to understand how these issues can lead to instability and even collapse of the anaerobic system, severely limiting its practical engineering applications.
[0005] Therefore, in order to solve the above problems, providing a high-efficiency two-phase anaerobic system with advantages such as energy saving, mitigation of volatile acid accumulation, and tolerance to high ammonia and high organic load is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0006] In view of this, the present invention provides a method and apparatus for constructing a high-efficiency two-phase anaerobic digestion system at ambient temperature and mesophilic temperature.
[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for constructing a highly efficient two-phase anaerobic digestion system at ambient and mesophilic temperatures, comprising two parts: the construction of an ambient-temperature acid-producing anaerobic system and the construction of a mesophilic methanogenic anaerobic system; wherein... The construction of the ambient-temperature acid-producing anaerobic system includes an initial stage, a transition stage, and an enrichment stage 1; wherein... The initial stage involves using glucose as a carbon source to expand the culture of the inoculated sludge. The transition phase involves using glucose and sodium formate as carbon sources to selectively cultivate the inoculated sludge that has undergone the expanded culture, and the amount of sodium formate added gradually increases with the increase of the culture days. The enrichment stage 1 uses sodium formate as a carbon source to further enrich the inoculated sludge that has undergone selective culture to obtain sludge enriched with homo-acetic acid-producing bacteria. The construction of the mesophilic methanogenic anaerobic system involves gradually increasing the influent ammonia nitrogen concentration within the mesophilic anaerobic methanogenic system, including a start-up phase and an enrichment phase 2; wherein, The start-up phase involves using glucose and sodium acetate as carbon sources to start and cultivate the inoculated sludge. The enrichment stage 2 utilizes glucose and sodium acetate as carbon sources to gradually increase the ammonia nitrogen concentration in the influent, further enriching the inoculated sludge that has undergone selective culture, thereby obtaining sludge enriched with symbiotic acetic acid oxidizing bacteria-hydrogen-type methanogenic bacteria.
[0008] Preferably, the culture temperature for the initial stage, the transition stage, and the enrichment stage is 23-25°C, and no additional inhibitors are needed to suppress methanogens.
[0009] Preferably, during the transition phase, the initial dosage of sodium formate is 0.8-1.2 g / L, and the dosage of sodium formate is increased by 1.0-2.0 g / L every 15-20 days.
[0010] Preferably, during the transition phase, the amount of glucose added is 3.0-4.0 g / L, and the amount of glucose added gradually decreases as the number of cultivation days increases.
[0011] Preferably, in the enrichment stage 1, the amount of sodium formate added gradually increases with the increase of the number of cultivation days.
[0012] Preferably, the incubation temperature for both the initiation stage and the enrichment stage 2 is 35°C.
[0013] Preferably, during the start-up phase, the initial dosage of glucose and sodium acetate is 0.5 / 0.68 g / L, and then gradually increased to 2.0 / 2.73 g / L.
[0014] Preferably, in the enrichment stage 2, the dosage of glucose and sodium acetate is kept constant at 2.0 / 2.73 g / L, and the dosage of ammonia nitrogen is increased from 1.0 g NH4. + / L gradually increased to 6.0 g NH4 + / L.
[0015] Preferably, the system includes an ambient temperature acid-producing anaerobic system and a mesophilic methanogenic anaerobic system. The ambient temperature acid-producing anaerobic system uses a continuous stirred reactor (CSTR) system as the reactor; the mesophilic methanogenic anaerobic system uses an upflow anaerobic sludge blanket (UASB) system as the reactor; the ambient temperature acid-producing anaerobic system is inoculated with flocculent sludge enriched with homotrophic acetogenic bacteria; the mesophilic methanogenic anaerobic system is inoculated with granular sludge enriched with symbiotic acetogenic bacteria-hydrogen-type methanogens (SAOB-HM). The culture temperatures for the ambient temperature acid-producing anaerobic system and the mesophilic methanogenic anaerobic system were 24 ± 1℃ and 35 ± 1℃, respectively. An equalization tank is connected between the acid-producing anaerobic system and the methanogenic anaerobic system to adjust the difference in hydraulic retention time between the two systems. A device for constructing a high-efficiency two-phase anaerobic digestion system at ambient and mesophilic temperatures, the device comprising a sample inlet, a reactor, and a gas collection bag; a peristaltic pump is connected between the sample inlet and the reactor, and the reactor and the peristaltic pump, as well as the sample inlet and the peristaltic pump, are connected by silicone tubing; The ambient temperature acid-producing reactor contains sludge enriched with homo-acetic acid-producing bacteria, while the mesophilic methanogenic reactor contains sludge enriched with syntrophic acetic acid-oxidizing bacteria-hydrogen-producing bacteria. Each acid-producing reactor is equipped with a stirring system to ensure thorough mixing of the substrate and inoculated sludge. Each reactor is also equipped with a constant-temperature water bath circulation system to ensure stable operation at the set temperature. Silicone gaskets are installed at the connection between the stirrer and the reactor, as well as at all gaps, to prevent air leakage. Each reactor is equipped with an aluminum foil gas collection bag for collecting gas, which is connected to the top of the reactor via a pipe. The daily volume of biogas collected by the aluminum foil gas collection bag is measured using a connected wet gas flow meter. A suction bottle is connected between the aluminum foil gas collection bag and the wet gas flow meter to prevent backflow.
[0016] The present invention achieves the following technical effects compared to the prior art: (1) The ambient temperature acid-producing anaerobic system constructed in this invention does not require additional energy, thus significantly reducing operating costs. Furthermore, during the enrichment of homoacetic bacteria, no methanogen inhibitors need to be added, thus avoiding secondary environmental pollution. The enriched ambient temperature acid-producing anaerobic system promotes the flow of more carbon sources to small molecule acids such as formic acid and acetic acid, effectively reducing the accumulation of volatile acids such as propionic acid and butyric acid. (2) In the mesophilic methanogenic anaerobic system constructed in this invention, symbiotic acetic acid oxidizing bacteria-hydrogen-progenitor bacteria (SAOB-HM) were successfully enriched. SAOB-HM has a certain tolerance to high ammonia stress and high organic loading rate, which enhances the tolerance of the methanogenic phase system to high organic loading rate and high ammonia stress. (3) The ambient temperature-mesotemperature high-efficiency two-phase anaerobic system constructed in this invention has the advantages of energy saving, alleviating the accumulation of volatile acids and being resistant to high ammonia and high organic load. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the high-efficiency two-phase anaerobic device of the present invention; Figure 2 This is a diagram illustrating the generation of volatile acids according to an embodiment of the present invention. In this diagram, a represents the VFAs formation of acetic acid and propionic acid, and b represents the VFAs formation of the methanogenic phase. Figure 3 This diagram illustrates the biogas generation process according to an embodiment of the present invention. Detailed Implementation
[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] This invention discloses a method for constructing a highly efficient two-phase anaerobic digestion system at ambient and mesophilic temperatures, comprising two parts: the construction of an ambient-temperature acid-producing anaerobic system and the construction of a mesophilic methanogenic anaerobic system; wherein, The construction of an ambient-temperature acid-producing anaerobic system includes an initial stage, a transition stage, and an enrichment stage 1; among which, The initial stage involves using glucose as a carbon source to scale up the cultivation of the inoculated sludge; The transition phase involves using glucose and sodium formate as carbon sources to selectively cultivate the inoculated sludge after expanded cultivation, with the amount of sodium formate gradually increasing as the cultivation days increase. Enrichment stage 1 uses sodium formate as a carbon source to further enrich the selectively cultured inoculated sludge, resulting in sludge enriched with homo-type acetic acid-producing bacteria. The construction of a mesophilic methanogenic anaerobic system involves gradually increasing the influent ammonia nitrogen concentration within the mesophilic anaerobic methanogenic system, including a start-up phase and an enrichment phase 2; among which, The start-up phase involves using glucose and sodium acetate as carbon sources to start and cultivate the inoculated sludge. Enrichment stage 2 utilizes glucose and sodium acetate as carbon sources to gradually increase the ammonia nitrogen concentration in the influent, further enriching the selectively cultured inoculated sludge to obtain sludge enriched with symbiotic acetic acid oxidizing bacteria-hydrogen-type methanogenic bacteria.
[0020] The culture temperature for the initial, transition, and enrichment stages is 23-25℃, and no additional inhibitors are needed to suppress methanogens.
[0021] During the transition phase, the initial dosage of sodium formate is 0.8-1.2 g / L, and the dosage is increased by 1.0-2.0 g / L every 15-20 days.
[0022] During the transition phase, the amount of glucose added was 3.0-4.0 g / L, and the amount of glucose added gradually decreased as the number of culture days increased.
[0023] In enrichment stage 1, the amount of sodium formate added gradually increased with the increase of culture days.
[0024] The incubation temperature for both the start-up phase and the enrichment phase 2 was 35℃.
[0025] During the initial stage, the initial dosage of glucose and sodium acetate was 0.5 / 0.68 g / L, and then gradually increased to 2.0 / 2.73 g / L.
[0026] In enrichment stage 2, the dosage of glucose and sodium acetate remained stable at 2.0 / 2.73 g / L, while the dosage of ammonia nitrogen increased from 1.0 g NH4. + / L gradually increased to 6.0 g NH4 + / L.
[0027] The system includes an ambient temperature acid-producing anaerobic system and a mesophilic methanogenic anaerobic system. The ambient temperature acid-producing anaerobic system uses a continuous stirred reactor (CSTR) system as the reactor; the mesophilic methanogenic anaerobic system uses an upflow anaerobic sludge blanket (UASB) system as the reactor. The ambient temperature acid-producing anaerobic system is inoculated with flocculent sludge enriched with homotrophic acetogenic bacteria; the mesophilic methanogenic anaerobic system is inoculated with granular sludge enriched with symbiotic acetogenic bacteria-hydrogen-type methanogens (SAOB-HM). The culture temperatures for the ambient-temperature acid-producing anaerobic system and the mesophilic methanogenic anaerobic system were 24 ± 1 ℃ and 35 ± 1 ℃, respectively. An equalization tank is connected between the acid-producing anaerobic system and the methanogenic anaerobic system to adjust the difference in hydraulic retention time between the two systems; In this invention, a traditional mesophilic acid-producing anaerobic system and a traditional mesophilic methanogenic anaerobic system are used as control groups; In this invention, the mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) of the inoculated sludge in the test group and control group were as follows: CSTR-control: 18.15 ± 0.08, 16.31 ± 0.10; CSTR-test: 24.75 ± 0.41, 10.54 ± 0.34; UASB-control: 18.56 ± 0.18, 17.04 ± 0.12; UASB-test: 12.45 ± 0.10, 11.33 ± 0.10. In this invention, a 50-mesh sieve is used to filter and pretreat the leachate from kitchen waste to remove large solid particles. The construction and operation of a high-efficiency two-phase anaerobic system includes an organic load regulation stage and a high ammonia regulation stage. During the organic load regulation stage, leachate from the three-phase separation of kitchen waste was used as a carbon source to adapt the inoculated sludge, and the amount of leachate added gradually increased as the organic load rate was regulated. The high ammonia regulation stage involves maintaining the influent COD concentration at 5000 mg / L after the organic load regulation is completed, and then gradually increasing the influent ammonia nitrogen concentration. The substrates added during the organic loading control stage and the ammonia nitrogen concentration control stage are shown in Table 1: Table 1. Operating parameters of the reactor at different stages In this invention, when the constructed ambient-temperature acid-producing anaerobic system is used to treat pollutants with high organic loads and high ammonia nitrogen levels, the homoacetic-producing bacteria enriched within the system optimize the acid-producing structure to a certain extent, directing more carbon sources toward low-carbon volatile acids such as formic acid and acetic acid, thus providing higher-quality substrates for the subsequent mesophilic methanogenic phase system. Furthermore, the ambient-temperature acid-producing phase system exhibits a certain tolerance to high ammonia levels. In this invention, the constructed intermediate-temperature methanogenic phase system utilizes the acetic acid produced in the room-temperature acidogenic phase system to generate methane. The methane generation pathway is the syntrophic acetic acid oxidation-hydrogenation methanogenic pathway. This pathway is characterized by its high tolerance to high ammonia stress. The present invention also discloses a device for constructing a high-efficiency two-phase anaerobic digestion system at ambient temperature and mesophilic temperature. The device includes a sample inlet, a reactor, and a gas collection bag. A peristaltic pump is connected between the sample inlet and the reactor, and the reactor and the peristaltic pump, as well as the sample inlet and the peristaltic pump, are connected by silicone tubes. The ambient temperature acid-producing reactor contains sludge enriched with homologous acetic-producing bacteria, while the mesophilic methanogenic reactor contains sludge enriched with syntrophic acetic-oxidizing bacteria-hydrogen-producing bacteria. The acid-producing reactor is equipped with a stirring system to ensure thorough mixing of the substrate and inoculated sludge. Each reactor is equipped with a constant-temperature water bath circulation system to ensure stable operation at the set temperature. Silicone gaskets are installed at the connection between the stirrer and the reactor, as well as at all gaps, to prevent air leakage. Each reactor is equipped with an aluminum foil gas collection bag for collecting gas, which is connected to the top of the reactor via a pipe. The daily volume of biogas collected by the aluminum foil gas collection bag is measured using a connected wet gas flow meter. A suction bottle is connected between the aluminum foil gas collection bag and the wet gas flow meter to prevent backflow.
[0028] The working principle of the device of the present invention is as follows: like Figure 1 As shown, before the anaerobic fermentation unit was put into operation, the ambient temperature acid-producing phase system and the mesophilic methanogenic phase system were enriched with homoacetic bacteria and syntrophic acetic oxidizing bacteria-hydrogen-progenitors, respectively. The substrate, leachate from kitchen waste, used for anaerobic fermentation, was placed in a sample inlet and pumped into the acid-producing phase reactor at a constant flow rate via a peristaltic pump. During anaerobic fermentation and acid production in the reactor, the wastewater and sludge were mechanically stirred by a stirring paddle for better mixing. A small CSTR reactor was connected between the acid-producing and methanogenic phase systems as a regulating tank. The effluent from the acid-producing phase reactor was pumped into the methanogenic phase system as a substrate. The substrate produced by the acid-producing phase system had a higher proportion of acetic acid and formic acid, providing a higher quality substrate for the methanogenic phase system.
[0029] Example 1: 1. Formation of volatile acids like Figure 2 The figure shows the volatile acid production in the acid-producing phase and methanogenic phase of the constructed high-efficiency two-phase anaerobic system. Figure 2 As shown in (a), acetic acid and propionic acid are the main VFAs produced in the device, accounting for the largest proportion. The total VFA concentration and acetic acid concentration in the device of the example increase with increasing organic load, reaching their highest values at 7000 mg / L, at 3474.34 mg HAc / L and approximately 2000 mg HAc / L, respectively. However, higher organic loads inhibit VFA production.
[0030] From the perspective of VFAs generation in the methanogenic phase ( Figure 2 (b) The methanogenic phase system of the example, when faced with high ammonia stress (6000 mg NH4), + No severe VFAs accumulation occurred ( / L), and the total VFAs concentration was approximately 100–400 mg HAc / L.
[0031] 2. Biogas production like Figure 3 The diagram illustrates the biogas production in this embodiment, with the main gas components being CH4 and CO2. As the influent COD concentration increases, the methane yield and daily biogas production peak at 7000 mg COD / L, reaching 332.15 mL CH4 / g COD and 13150 mL, respectively. However, higher organic loading (10000 mg COD / L) somewhat inhibits biogas production, reducing the methane yield and daily biogas production to approximately 120-160 mL CH4 / g COD and 7000 mL, respectively. Even at higher ammonia nitrogen concentrations (6000 mg NH4), biogas production remains relatively stable. + ( / L), the examples also maintain high methane yield and daily gas production, approximately 180-190 mL CH4 / g COD and 3000-4000 mL, respectively.
[0032] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims
1. A method for constructing a high-efficiency two-phase anaerobic digestion system at ambient and mesophilic temperatures, characterized in that, The method comprises two parts: the construction of an ambient-temperature acid-producing anaerobic system and the construction of a mesophilic methanogenic anaerobic system; wherein... The construction of the ambient-temperature acid-producing anaerobic system includes an initial stage, a transition stage, and an enrichment stage 1; wherein... The initial stage involves using glucose as a carbon source to expand the culture of the inoculated sludge. The transition phase involves using glucose and sodium formate as carbon sources to selectively cultivate the inoculated sludge that has undergone the expanded culture, and the amount of sodium formate added gradually increases with the increase of the culture days. The enrichment stage 1 uses sodium formate as a carbon source to further enrich the inoculated sludge that has undergone selective culture to obtain sludge enriched with homo-acetic acid-producing bacteria. The construction of the mesophilic methanogenic anaerobic system involves gradually increasing the concentration of ammonia nitrogen in the influent within the mesophilic anaerobic methanogenic system, including a start-up phase and an enrichment phase 2. The start-up phase involves using glucose and sodium acetate as carbon sources to start and cultivate the inoculated sludge. The enrichment stage 2 utilizes glucose and sodium acetate as carbon sources to gradually increase the ammonia nitrogen concentration in the influent, further enriching the inoculated sludge that has undergone selective culture, thereby obtaining sludge enriched with symbiotic acetic acid oxidizing bacteria-hydrogen-type methanogenic bacteria.
2. The method for constructing a high-efficiency two-phase anaerobic digestion system at ambient temperature and mesophilic temperature according to claim 1, characterized in that, The culture temperature for the initial stage, the transition stage, and the enrichment stage is 23-25℃, and no additional inhibitors are required to suppress methanogens.
3. The method for constructing a high-efficiency two-phase anaerobic digestion system at ambient temperature and mesophilic temperature according to claim 1, characterized in that, During the transition phase, the initial dosage of sodium formate is 0.8-1.2 g / L, and the dosage of sodium formate is increased by 1.0-2.0 g / L every 15-20 days.
4. The method for constructing a high-efficiency two-phase anaerobic digestion system at ambient temperature and mesophilic temperature according to claim 1, characterized in that, During the transition phase, the amount of glucose added is 3.0-4.0 g / L, and the amount of glucose added gradually decreases as the number of culture days increases.
5. The method for constructing a high-efficiency two-phase anaerobic digestion system at ambient temperature and mesophilic temperature according to claim 1, characterized in that, In the enrichment stage 1, the amount of sodium formate added gradually increases with the increase of the number of cultivation days.
6. The method for constructing a high-efficiency two-phase anaerobic digestion system at ambient temperature and mesophilic temperature according to claim 1, characterized in that, The incubation temperature for both the initiation phase and the enrichment phase 2 is 35℃.
7. The method for constructing a high-efficiency two-phase anaerobic digestion system at ambient temperature and mesophilic temperature according to claim 1, characterized in that, During the initial startup phase, the initial dosage of glucose and sodium acetate was 0.5 / 0.68 g / L, which was then gradually increased to 2.0 / 2.73 g / L.
8. The method for constructing a high-efficiency two-phase anaerobic digestion system at ambient temperature and mesophilic temperature according to claim 1, characterized in that, In the enrichment stage 2, the dosage of glucose and sodium acetate was kept constant at 2.0 / 2.73 g / L, and the dosage of ammonia nitrogen was increased from 1.0 g NH4. + / L gradually increased to 6.0 g NH4 + / L.
9. The method for constructing a high-efficiency two-phase anaerobic digestion system at ambient temperature and mesophilic temperature according to claim 1, characterized in that, The system comprises an ambient-temperature acid-producing anaerobic system and a mesophilic methanogenic anaerobic system. The ambient-temperature acid-producing anaerobic system uses a continuous stirred reactor (CSTR) system as the reactor; the mesophilic methanogenic anaerobic system uses an upflow anaerobic sludge blanket (UASB) system as the reactor. The ambient-temperature acid-producing anaerobic system is inoculated with flocculent sludge enriched with homotrophic acetogenic bacteria; the mesophilic methanogenic anaerobic system is inoculated with granular sludge enriched with symbiotic acetogenic bacteria-hydrogen-type methanogens (SAOB-HM). The culture temperatures for the ambient temperature acid-producing anaerobic system and the mesophilic methanogenic anaerobic system were 24 ± 1 ℃ and 35 ± 1 ℃, respectively. An equalization tank is connected between the acid-producing anaerobic system and the methanogenic anaerobic system to adjust the difference in hydraulic retention time between the two systems.
10. A device for constructing a high-efficiency two-phase anaerobic digestion system at ambient and mesophilic temperatures, characterized in that, The device includes a sample inlet, a reactor, and a gas collection bag; a peristaltic pump is connected between the sample inlet and the reactor, and the reactor and the peristaltic pump, as well as the sample inlet and the peristaltic pump, are connected by silicone tubing; The ambient temperature acid-producing reactor contains sludge enriched with homo-acetic acid-producing bacteria, while the mesophilic methanogenic reactor contains sludge enriched with syntrophic acetic acid-oxidizing bacteria-hydrogen-producing bacteria. Each acid-producing reactor is equipped with a stirring system to ensure thorough mixing of the substrate and inoculated sludge. Each reactor is also equipped with a constant-temperature water bath circulation system to ensure stable operation at the set temperature. Silicone gaskets are installed at the connection between the stirrer and the reactor, as well as at all gaps, to prevent air leakage. Each reactor is equipped with an aluminum foil gas collection bag for collecting gas, which is connected to the top of the reactor via a pipe. The daily volume of biogas collected by the aluminum foil gas collection bag is measured using a connected wet gas flow meter. A suction bottle is connected between the aluminum foil gas collection bag and the wet gas flow meter to prevent backflow.