Microbial agent for efficiently producing acid by fermenting organic wastes and application of microbial agent

Abstract

The invention provides a microbial agent for producing acid through fermentation of organic waste and application of the microbial agent, and relates to the technical field of biology, the microbial agent contains Acetobacter xylinum, Clostridium bovifaecis and Eubacter mucilaginosus, and the microbial agent is prepared from the following raw materials: Acetobacter xylinum, Clostridium bovifaecis and Eubacter mucilaginosus. Studies find that acetobacter burgii, clostridium cow dung and eubacterium mucilaginosus complement each other in the anaerobic fermentation process, the degradation efficiency of organic matters such as carbohydrates and proteins in the organic wastewater / perishable garbage is improved, the yield of volatile fatty acids is remarkably increased, meanwhile, the emission of CO2 is reduced, and the environmental pollution is reduced. The method has the application prospects of organic wastewater / perishable garbage treatment and recycling. When the acid-producing bacterium agent is applied to organic wastewater / perishable garbage, the fermented mixed acid liquid is rich in VFA and can be used as an organic carbon source, and the additional value is higher; when the acid-producing bacterium agent is applied to organic wastewater / perishable garbage, the operation is simple and convenient, the cost is low, biogas slurry treatment links and cost are reduced, the added value of products can be improved, and the acid-producing bacterium agent has an engineering application prospect.

Description

Technical Field

[0001] The present invention relates to the field of environmental biotechnology, and more particularly, to a bacterial agent for highly efficient acid production by organic waste fermentation and its application. Background Art

[0002] Organic industrial wastewater and municipal perishable garbage, such as kitchen waste, municipal sludge, crop straws, livestock and poultry manure, etc., are rich in nutrients such as lipids, proteins, carbohydrates, minerals, etc., and usually anaerobic biological methods are used for harmless, stable and resource utilization treatment. How to maximize the conversion of organic matter into volatile fatty acids (VFAs) is the key to anaerobic biological treatment.

[0003] Homoacetogens are a class of anaerobic microorganisms that convert 2 molecules of CO2 into 1 molecule of acetic acid through the Wood-Ljungdahl pathway. Homoacetogens are widely present in anaerobic habitats, and the amount of acetic acid synthesized by them accounts for about 10% of the amount synthesized by anaerobic microorganisms. Taking the homoacetogenic action of glucose as an example, fermenting 1 mol of glucose can produce 3 mol of acetic acid without CO2 release, producing 1 more molecule of acetic acid compared to classical fermentation. Therefore, homoacetogens are industrial microorganisms with great development potential. Applying them to anaerobic fermentation of organic waste to produce acid can not only increase the acid production rate but also reduce carbon emissions. Therefore, homoacetogens have great application prospects in the aspect of using organic solid waste fermentation to produce acid.

[0004] The prior art has disclosed the application of various acetic acid-producing bacteria in acid production. For example, the Chinese invention patent with the publication number CN112410251A discloses a Lactobacillus plantarum with fast acid production and high acid production capacity and its application. This invention uses Lactobacillus plantarum, a lactic acid bacterium, to ferment and produce lactic acid for the production of fermented feed. As a silage additive, this bacterial agent utilizes carbohydrates in the raw materials to form organic acids such as lactic acid during the silage fermentation process, and creates an anaerobic acidic environment, thereby inhibiting the growth of spoilage bacteria such as yeast and mold, and then limitedly preserving the nutrient components of the raw materials. For example, the Chinese invention patent with the publication number CN 113789284A proposes an acid-producing bacterium, an acid-producing bacterial agent and its application for treating livestock and poultry manure sewage. This low-temperature lactic acid bacterium can decompose the organic matter in high-salt livestock and poultry manure sewage to produce acid, and then provide it to methanogens to increase methane production. For example, the Chinese invention patent with the publication number CN115109725A discloses a method for enriching homoacetogenic bacteria at room temperature and its application. It discloses a method for enriching homoacetogenic bacteria and uses various homoacetogenic bacteria sludge to treat sewage. However, a single strain has a poor effect on acid production, which is not conducive to efficient acid production and carbon emission reduction; using homoacetogenic bacteria containing multiple bacteria, the composition of the strains is not clear, which is not conducive to large-scale cultivation and industrial application. Therefore, it is necessary to develop a combined strain with a clear composition and content of homoacetogenic bacteria to efficiently produce acid, reduce carbon emissions, and facilitate industrial application. Summary of the Invention

[0005] The object of the present invention is to solve the above technical problems and provide a bacterial agent for fermenting organic waste to produce acid. This bacterial agent for fermenting organic waste to produce acid can efficiently produce acid, reduce carbon emissions, and facilitate industrial application; another object of the present invention is to provide a preparation method of this bacterial agent for fermenting organic waste to produce acid; still another object of the present invention is to provide the application of this bacterial agent for fermenting organic waste to produce acid.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A bacterial agent for fermenting organic waste to produce acid, characterized in that the bacterial agent contains Acetobacterium woodii, Clostridium bovifaecis and Eubacterium limosum.

[0008] The present invention discovers through research that Acetobacterium woodii, Clostridium bovifaecis and Eubacterium limosum complement each other during anaerobic fermentation, improve the degradation efficiency of organic substances such as carbohydrates and proteins in organic wastewater / perishable garbage, significantly increase the production of volatile fatty acids, and at the same time reduce CO2 emissions, having the prospect of organic wastewater / perishable garbage treatment and resource utilization.

[0009] Furthermore, the concentration ratio of Acetobacter woodii, Clostridium bovifaecis, and Eubacterium limosum is 1:1-2:1-2. Preferably, the concentration ratio of Acetobacter woodii, Clostridium bovifaecis, and Eubacterium limosum is 1:1:1.

[0010] Furthermore, Clostridium bovifaecis has been deposited in the China General Microbiological Culture Collection Center with the deposit number CGMCC 1.5228.

[0011] Furthermore, the microbial agent is a liquid bacterial solution, and the OD600 value of the bacterial solution is 4-6.

[0012] Furthermore, the above microbial agent is prepared by the following method: inoculating Acetobacter woodii, Clostridium bovifaecis, and Eubacterium limosum into a fermentation medium respectively, and culturing under the conditions of a mixed gas of N2 / CO2 with a volume percentage of 70-80:20-30 and a temperature of 20-40 °C for 48-72 h to obtain the fermentation broths of Acetobacter woodii, Clostridium bovifaecis, and Eubacterium limosum, and then mixing the fermentation broths of Acetobacter woodii, Clostridium bovifaecis, and Eubacterium limosum to obtain the microbial agent for organic waste fermentation to produce acid.

[0013] The present invention provides the application of the above microbial agent for organic waste fermentation to produce acid in the treatment or resource utilization of organic wastewater / perishable garbage.

[0014] The present invention provides the application of the above microbial agent for organic waste fermentation to produce acid in the fermentation preparation of a mixed acid solution.

[0015] Furthermore, this application is to inoculate the microbial agent for organic waste fermentation to produce acid into organic wastewater / perishable garbage, control the hydraulic retention time to inhibit methane production for anaerobic fermentation to produce acid, and obtain a mixed acid solution through anaerobic fermentation.

[0016] Furthermore, the organic wastewater / perishable garbage is food waste wastewater, molasses wastewater, pretreated liquid of excess sludge, food waste, and fruit and vegetable waste.

[0017] Even further, the inoculation amount of the microbial agent for organic waste fermentation to produce acid is 1-5%.

[0018] Even further, the above application includes the following steps:

[0019] S1. Inoculate the microbial agent for organic waste fermentation to produce acid into organic wastewater / perishable garbage, and control the initial pH value of the fermentation system to be 7.0-10.0;

[0020] S2. Add an inorganic carbon source to the organic wastewater / perishable garbage. The inorganic carbon source is CO2 or bicarbonate, and the bicarbonate is sodium bicarbonate, potassium bicarbonate or ammonium bicarbonate; the concentration of CO2 is 2 - 15 mmol / L, and the concentration of bicarbonate is 1 - 10 g / L.

[0021] S3. Control the hydraulic retention time to inhibit methane production and carry out anaerobic fermentation to produce acid. The temperature of the anaerobic fermentation is 25 - 40 °C, the hydraulic retention time is controlled to 3 - 7 days, and a mixed acid solution is obtained through anaerobic fermentation.

[0022] Furthermore, the initial pH value of the fermentation system is 7.0 - 8.0.

[0023] Furthermore, the temperature of the anaerobic fermentation is 35 °C.

[0024] The beneficial effects of the present invention are as follows:

[0025] (1) Through research, the present invention finds that there is no inhibitory antagonism among Acetobacterium woodii, Clostridium bifermentans and Eubacterium limosum. The three bacteria complement each other during anaerobic fermentation, improving the degradation efficiency of organic substances such as carbohydrates and proteins in organic wastewater / perishable garbage.

[0026] (2) The present invention only adds an acid-producing bacterial agent at the initial stage of anaerobic fermentation for producing acid from organic wastewater / perishable garbage, which can ensure the stability of each anaerobic fermentation. Compared with not adding a compound bacterial agent, the volatile fatty acid yield is increased by more than 50%, and the CO2 emission is reduced by more than 8%.

[0027] (3) When the acid-producing bacterial agent of the present invention is applied to organic wastewater / perishable garbage, the addition of the carbon source is economical and easily available. The fermented mixed acid solution is rich in VFAs and can be used as an organic carbon source, with higher added value.

[0028] (4) When the acid-producing bacterial agent of the present invention is applied to organic wastewater / perishable garbage, it is not only simple to operate, low in cost, reduces the biogas slurry treatment link and cost, but also can improve the product added value, having the prospect of engineering application. Description of the Drawings

[0029] Figure 1 It is the change of VFAs (A) and CO2 concentration (B) in Example 1 of the present invention.

[0030] Figure 2 It is the change of VFAs (A) and CO2 concentration (B) in Example 2 of the present invention.

[0031] Figure 3 It is the change of VFAs (A) and CO2 concentration (B) in Comparative Example 1 of the present invention.

[0032] Figure 4VFA (A) and CO2 concentration change (B) in Comparative Example 2 of the present invention. Detailed implementation manners

[0033] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0034] The raw materials used in this embodiment are described as follows:

[0035] The kitchen waste wastewater is the kitchen waste slurry after simple pressing by a kitchen waste treatment company in Wuxi City, Jiangsu Province, removing impurities (bones, paper, plastics, etc.), mixing and crushing the water, and removing the surface floating oil by heat treatment. The composite bacteria include the bacterium Acetobacterium woodii with the preservation number of ATCC 29683, Clostridium bovifae with the preservation number of CGMCC 1.5228, and the bacterium Eubacterium limosum with the preservation number of ATCC 8486. The above strains are all commercially available preserved bacteria. Among them, Clostridium bovifae has been previously studied by the research group of the present inventor and is published in the relevant journal: Zhu H, Fu B, Lu S, et al. Clostridium bovifaecis sp. nov., a novel acetogenic bacterium isolated from cow manure [J]. International Journal of Systematic and Evolutionary Microbiology, 2018, 68(9). DOI: 10.1099 / ijsem.0.002928, and is the preserved strain.

[0036] Example 1

[0037] (1) Preparation of the bacterium agent for organic waste fermentation to produce acid

[0038] This embodiment provides a bacterial agent for fermenting organic waste to produce acid. The bacterial agent is a liquid bacterial solution, and the bacterial agent contains Acetobacterium woodii, Clostridium bovifaecis, and Eubacterium limosum. The bacterial agent is prepared by the following method: inoculating Acetobacterium woodii, Clostridium bovifaecis, and Eubacterium limosum into a fermentation medium respectively, and performing anaerobic culture to obtain fermentation broths of Acetobacterium woodii, Clostridium bovifaecis, and Eubacterium limosum, and then mixing the fermentation broths of Acetobacterium woodii, Clostridium bovifaecis, and Eubacterium limosum to obtain the bacterial agent for fermenting organic waste to produce acid.

[0039] The specific method is as follows: Cultivate three homoacetogenic bacteria, namely Acetobacterium woodii, Clostridium bovifaecis, and Eubacterium limosum. The culture experiment is carried out in a 650 mL anaerobic serum bottle containing 200 mL of liquid DSMZ medium 135. The pH of the medium is adjusted to 7.0. The headspace of the serum bottle is filled with N2 / CO2 (v / v, 80:20) for 15 - 20 min to maintain anaerobic conditions. The culture is carried out in a constant temperature incubator at 30 °C until the middle and late logarithmic phase, and the OD 600 values are 1.12, 1.71, and 1.47 respectively. Centrifuge the three bacterial solutions at 8000 rpm for 10 min respectively, then resuspend them with a sugar-free DSMZ135 medium solution, and mix the three bacterial solutions in a ratio of 1:1:1 to obtain a composite bacterial agent. The final OD 600 value is 5 - 6, which is the bacterial agent for fermenting organic waste to produce acid.

[0040] Among them, the nutrients in the medium are 1.0 g / L NH4Cl, 0.4 g / L NaCl, 0.45 g / L K2HPO4, 0.33 g / L KH2PO4, 0.1 g / L MgSO4·7H2O, 10 g / L NaHCO3, 0.5 g / L L-cysteine·HCl·H2O, 2.0 g / L yeast powder, 2 ml / L trace elements, 1 ml / L vitamins, and 0.5 ml / L resazurin sodium.

[0041] The vitamin solution is: 2 mg / L biotin, 2 mg / L folic acid, 10 mg / L vitamin B6 hydrochloride, 5 mg / L vitamin B1 hydrochloride, 5 mg / L vitamin B2, 5 mg / L vitamin B3, 5 mg / L D-calcium pantothenate, 0.1 mg / L vitamin B12, 5 mg / L p-aminobenzoic acid, and 5 mg / L DL-malic acid.

[0042] The trace element solution is: 10 mL of hydrochloric acid (25% v / v), 1.5 g / L of FeCl2·4H2O, 0.07 g / L of ZnCl, 0.1 g / L of MnCl2·4H2O, 6 mg / L of H3BO3, 0.19 g / L of CoCl2·6H2O, 2 mg / L of CuCl2·2H2O, 24 mg / L of NiCl2·6H2O, 36 mg / L of Na2MoO4·2H2O.

[0043] (2) Application of the microbial agent for organic waste fermentation to produce acid

[0044] This example also provides the application of the above-mentioned microbial agent for organic waste fermentation to produce acid in the treatment or resource utilization of organic wastewater / perishable garbage. The application includes the following steps:

[0045] S1. Inoculate the microbial agent for organic waste fermentation to produce acid into the organic wastewater / perishable garbage, and control the initial pH value of the fermentation system;

[0046] S2. Add an inorganic carbon source to the organic wastewater / perishable garbage, and the inorganic carbon source is CO2;

[0047] S3. Control the hydraulic retention time to inhibit methane production and carry out anaerobic fermentation to produce acid, and obtain a mixed acid solution through anaerobic fermentation.

[0048] The specific method is as follows:

[0049] Add 300 mL of kitchen waste slurry (fermentation substrate) to a 650 mL serum bottle, add 2 g / L of BES to inhibit methane production, aerate the headspace of the serum bottle with N2 for 10 min, and adjust the initial pH to 7.0 with NaOH solution. Inoculate 5% of the above-mentioned microbial agent for organic waste fermentation to produce acid and fill the headspace with CO2 added at 10 mmol / L. Use the group without adding the microbial agent as the control group, and after anaerobic fermentation at 35°C for 10 days, obtain a mixed acid solution.

[0050] (3) Determination of volatile fatty acids and CO2 emissions in the mixed acid solution

[0051] Determine the volatile fatty acids and CO2 emissions during the fermentation process of the mixed acid solution, and the test methods and results are as follows:

[0052] a. Test method

[0053] Detection method of volatile fatty acids: The concentration of volatile fatty acids (including acetic acid, propionic acid, and butyric acid) was determined by gas chromatography. The samples obtained under various conditions were filtered through a 0.22 μm aqueous filter membrane and then mixed with phosphoric acid (acidifying agent) at a concentration of 3 mmol / L (1:1, volume ratio) and added to the injection vial. The concentration of VFAs in the sample was determined using a gas chromatograph. The gas chromatograph parameters were: automatic injector (AOC-20i), capillary column (PEG-20M, 30 m × 0.32 mm × 0.5 μm), hydrogen flame ionization detector (FID) with a detection limit of 3 pgC / s, high-purity N2 as the carrier gas, column oven temperature of 210 °C, and injection port and detector temperatures both set at 250 °C.

[0054] Determination of CO2 emissions: The concentration of CO2 was determined using a gas chromatograph. The carrier gas was high-purity argon, and the other gas chromatograph parameters were: thermal conductivity detector (TCD) and stainless steel packed column (AE.TDX-01, 2 m × 3 mm). The analysis conditions were: column temperature of 100 °C, detector temperature and injection port temperature both set at 150 °C. Using a standard gas of CO2 as the standard sample, the detector current was adjusted to 80 mA, and 2.5 mL of gas was collected and analyzed using a manual injector.

[0055] b. Test results

[0056] The cumulative test results are shown in Table 1. The continuous statistical results of the test are Figure 1 as shown. It can be seen from Table 1 that the CO2 emissions of the control group were 23.40 ± 2.62 mmol / L, the VFA production was 28.58 ± 0.92 g COD / L, among which the acetic acid production was 4.26 ± 0.01 g COD / L, and the butyric acid production was 23.03 ± 0.75 g COD / L. It can be seen from Table 1 that the production of VFAs and butyric acid in the experimental group with the addition of the composite bacterium agent increased by 9.72% and 11.89% respectively, and the CO2 emissions decreased by 8.97%. It can be Figure 1 seen that the VFAs showed an increasing trend in both the control group and the bacterium agent group during the fermentation process, but the bacterium agent group was significantly higher than the control group; the CO2 emissions in the control group and the bacterium agent group showed different trends at different fermentation stages, but the overall CO2 emissions in the bacterium agent group were lower ( Figure 1 ).

[0057] Table 1 Acid production situation of anaerobic fermentation of food waste by CO2-regulating composite bacteria

[0058]

[0059] Example 2

[0060] (1) Preparation of bacterium agent for organic waste fermentation to produce acid

[0061] This embodiment provides a bacterial agent for fermenting organic waste to produce acid. The bacterial agent is a liquid bacterial solution, which contains Acetobacterium woodii, Clostridium bovifaecis, and Eubacterium limosum. The bacterial agent is prepared by the following method: inoculating Acetobacterium woodii, Clostridium bovifaecis, and Eubacterium limosum into a fermentation medium respectively, culturing anaerobically to obtain the fermentation broths of Acetobacterium woodii, Clostridium bovifaecis, and Eubacterium limosum, and then mixing the fermentation broths of Acetobacterium woodii, Clostridium bovifaecis, and Eubacterium limosum to obtain the bacterial agent for fermenting organic waste to produce acid.

[0062] The specific method is the same as the preparation of the bacterial agent for fermenting organic waste to produce acid in Example 1.

[0063] (2) Application of the bacterial agent for fermenting organic waste to produce acid

[0064] This embodiment also provides the application of the above-mentioned bacterial agent for fermenting organic waste to produce acid in treating or resource-utilizing organic wastewater / perishable garbage. The application includes the following steps:

[0065] S1. Inoculate the bacterial agent for fermenting organic waste to produce acid into organic wastewater / perishable garbage, and control the initial pH value of the fermentation system;

[0066] S2. Add an inorganic carbon source to the organic wastewater / perishable garbage, and the inorganic carbon source is bicarbonate;

[0067] S3. Control the hydraulic retention time to inhibit methane production and carry out anaerobic fermentation to produce acid, and the anaerobic fermentation obtains a mixed acid solution.

[0068] The specific method is as follows:

[0069] Add 300 mL of kitchen waste slurry (fermentation substrate) into a serum bottle with a volume of 650 mL, add 2 g / L of BES to inhibit methane production, aerate the headspace of the serum bottle with N2 for 10 min, and adjust the initial pH to 7.0 with NaOH solution. Inoculate 5% of the above-mentioned bacterial agent for fermenting organic waste to produce acid, and add 4 g / L of NaHCO3. The group without adding the bacterial agent is used as the control group. After anaerobic fermentation at 35 °C for 10 days, a mixed acid solution is obtained.

[0070] (3) Determination of volatile fatty acids and CO2 emissions of the mixed acid solution

[0071] During the fermentation process of the mixed acid solution, the volatile fatty acids and CO2 emissions are measured. The test methods and results are as follows:

[0072] a. Test method

[0073] The test method is the same as that in Example 1.

[0074] b. Test results

[0075] The cumulative test results are shown in Table 2. The continuous test statistics results and Figure 2 are shown as follows. As can be seen from Table 2, the CO2 emission of the control group is 23.40 ± 2.62 mmol / L, and the VFA production is 28.58 ± 0.92 g COD / L, among which the acetic acid production is 4.26 ± 0.01 g COD / L, and the butyric acid production is 23.03 ± 0.75 g COD / L. As can be seen from Table 2, the production of VFAs, acetic acid, and butyric acid in the experimental group with the addition of the composite bacterial agent increased by 74.91% and 40.72% respectively. From Figure 2 it can be seen that the VFAs showed an increasing trend in both the control group and the bacterial agent group during the fermentation process, but the bacterial agent group was significantly higher than the control group; the CO2 emissions in both the control group and the bacterial agent group showed an increasing trend at different fermentation stages, and the overall CO2 emissions of the bacterial agent group were higher.

[0076] Table 2 Acid production during anaerobic fermentation of food waste by composite bacteria regulated by NaHCO3

[0077]

[0078] Example 3

[0079] (1) Preparation of bacterial agent for organic waste fermentation to produce acid

[0080] The specific method is the same as the preparation of the bacterial agent for organic waste fermentation to produce acid in Example 1.

[0081] (2) Application of the bacterial agent for organic waste fermentation to produce acid

[0082] The specific method is as follows:

[0083] Add 300 mL of food waste slurry (fermentation substrate) into a serum bottle with a volume of 650 mL, add 2 g / L of BES to inhibit methane production, aerate the headspace of the serum bottle with N2 for 10 min, and adjust the initial pH to 7.0 with NaOH solution. The control group and the experimental group were inoculated with biogas slurry and the above composite bacteria respectively. Anaerobic fermentation was carried out at 35 °C for 10 days.

[0084] (3) Determination of volatile fatty acids and CO2 emissions in the mixed acid solution

[0085] During the fermentation process of the mixed acid solution, the volatile fatty acids and CO2 emissions were measured. The test methods and results are as follows:

[0086] a. Test method

[0087] The test method is the same as that in Example 1.

[0088] b. Test results

[0089] The test cumulative results are shown in Table 3, and the test continuous statistical results and Figure 3 are shown as follows. It can be seen from Table 3 that the CO2 emission of the biogas slurry group is 27.02±0.53 mmol / L, and the VFA production is 23.85±2.26 g COD / L. Compared with using biogas slurry as the inoculum, the VFA production of the bacterial agent group increased by 28.05% respectively, and the CO2 emission decreased by 5.07%. From Figure 3 it can be seen that VFAs showed an increasing trend in both the biogas slurry group and the bacterial agent group during the fermentation process, but the bacterial agent group was significantly higher than the biogas slurry group; the CO2 emissions of the biogas slurry group and the bacterial agent group showed an increasing trend at different fermentation stages, and the overall CO2 emission of the bacterial agent group was higher.

[0090] Table 3 Comparison of acid production from anaerobic fermentation of food waste using biogas slurry and composite bacteria as inoculants

[0091]

[0092] Example 4

[0093] This example verifies the influence of mixing different homoacetogenic bacteria strains on fermentation.

[0094] (1) Preparation of bacterial agent for organic waste fermentation to produce acid

[0095] The specific method is as follows: Four homoacetogenic bacteria strains, Clostridium aceticum, Acetobacterium woodii, Clostridium stercorarium, and Eubacterium limosum, were cultured separately. The culture experiment was carried out in a 650 mL anaerobic serum bottle containing 200 mL of liquid DSMZ medium 135. The pH of the medium was adjusted to 7.0. The headspace of the serum bottle was flushed with N2 / CO2 (v / v, 80:20) for 15 - 20 min to maintain anaerobic conditions, and then cultured in a constant temperature incubator at 30°C until the middle and late logarithmic phase.

[0096] (2) Application of different mixed bacteria

[0097] The specific method is as follows:

[0098] 300 mL of food waste slurry (fermentation substrate) was added to a 650 mL serum bottle, and 2 g / L of BES was added to inhibit methanogenesis. The headspace of the serum bottle was aerated with N2 for 10 min, and the initial pH was adjusted to 7.0 with NaOH solution. Five groups were set up: the group without inoculating the composite bacteria was used as the control group, and in experimental group 1, the composite bacteria inoculated were Clostridium aceticum, Acetobacterium woodii, and Clostridium stercorarium; in experimental group 2, the composite bacteria inoculated were Clostridium aceticum, Acetobacterium woodii, and Eubacterium limosum. In experimental group 3, the composite bacteria inoculated were Clostridium stercorarium, Acetobacterium woodii, and Eubacterium limosum. In experimental group 4, the composite bacteria inoculated were Clostridium aceticum, Clostridium stercorarium, Acetobacterium woodii, and Eubacterium limosum. After anaerobic fermentation at 35°C for 10 days, the CO2 emission of the control group was 30.77±0.25 mmol / L, and the VFA production was 23.35±1.19 g COD / L(Figure 4 )。As can be seen from Table 4, the acid production effect of the complex bacteria Clostridium aceticum, Acetobacter woodii, and Eubacterium limosum in experimental group 3 was the best, with a CO2 emission of 25.10 ± 0.38 mmol / L and a VFA production of 26.92 ± 1.45 g COD / L. Among them, the acetic acid production was 13.38 ± 1.06 g COD / L, and the butyric acid production was 12.20 ± 0.22 g COD / L. Compared with the control group, the production of VFAs and butyric acid increased by 15.29%, 8.16%, and 22.24% respectively, and the CO2 emission decreased by 18.43%.

[0099] Table 4 Acid production from food waste by different complex bacteria in anaerobic fermentation

[0100]

[0101]

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the solutions. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced on the basis of understanding the solutions, without departing from the purpose and scope of the technical solutions of the present invention, and all of them should be covered by the scope of the claims of the present invention.

Claims

1. A microbial agent for fermenting organic waste to produce acid, characterized in that, The microbial agent contains Acetobacterium woodii, Clostridium bovifaecis and Eubacterium limosum.

2. The microbial agent for fermenting organic waste to produce acid according to claim 1, characterized in that, The concentration ratio of Acetobacterium woodii, Clostridium bovifaecis and Eubacterium limosum is 1:1-2:1-2. Preferably, the concentration ratio of Acetobacterium woodii, Clostridium bovifaecis and Eubacterium limosum is 1:1:

1.

3. The microbial agent for fermenting organic waste to produce acid according to claim 1, wherein The microbial agent is a liquid microbial solution, and the OD600 value of the microbial solution is 4-6.

4. The microbial agent for fermenting organic waste to produce acid according to claim 3, wherein The microbial agent is prepared by the following method: inoculating Acetobacterium woodii, Clostridium bovifaecis and Eubacterium limosum into a fermentation medium respectively, and culturing under the conditions of N2 / CO2 mixed gas with a volume percentage of 70-80:20-30 and a temperature of 20-40 °C for 48-72 h to obtain fermentation broths of Acetobacterium woodii, Clostridium bovifaecis and Eubacterium limosum, and then mixing the fermentation broths of Acetobacterium woodii, Clostridium bovifaecis and Eubacterium limosum to obtain the microbial agent for acid production by organic waste fermentation.

5. Application of the microbial agent for acid production by organic waste fermentation according to any one of claims 1-4 in treating or resource-utilizing organic wastewater / perishable garbage.

6. Application of the microbial agent for acid production by organic waste fermentation according to any one of claims 1-4 in fermenting to prepare a mixed acid solution.

7. The application according to claim 6, characterized in that, Inoculate the microbial agent for acid production by organic waste fermentation into organic wastewater / perishable garbage, control the hydraulic retention time to inhibit methane production and carry out anaerobic fermentation for acid production, and obtain a mixed acid solution by anaerobic fermentation.

8. The application according to claim 7, wherein The organic wastewater / perishable garbage is kitchen waste wastewater, molasses wastewater, pretreated liquid of excess sludge, kitchen waste, and fruit and vegetable waste.

9. The application according to claim 8, wherein The inoculation amount of the microbial agent for acid production by organic waste fermentation is 1-5%.

10. The application according to claim 9, characterized in that, Comprising the following steps: S1. Inoculate the microbial agent for acid production by organic waste fermentation into organic wastewater / perishable garbage, and control the initial pH value of the fermentation system to be 7.0-10.0; S2. Add an inorganic carbon source to the organic wastewater / perishable garbage, the inorganic carbon source is CO2 or bicarbonate, and the bicarbonate is sodium bicarbonate, potassium bicarbonate or ammonium bicarbonate; the concentration of CO2 is 2-15 mmol / L, and the concentration of bicarbonate is 1-10 g / L; S3. Control the hydraulic retention time to inhibit methane production and carry out anaerobic fermentation for acid production, the temperature of the anaerobic fermentation is 25-40 °C, the hydraulic retention time is controlled to be 3-7 days, and a mixed acid solution is obtained by anaerobic fermentation.

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