Nitrogen-fixing bacteria for wastewater treatment and culture method and application thereof

Abstract

The present application relates to the field of microorganisms, in particular to a kind of nitrogen-loving bacteria for wastewater treatment and its culture method and application.The nitrogen-loving bacteria of the present application is Paracoccus Paracoccus sp. HF-E2025009, preserved in China General Microbiological Culture Collection Center on December 8, 2025, with the preservation number of CGMCC No.36935.The strain can maintain stable ammonia oxidation activity under high ammonia nitrogen and high sulfate conditions;the system can be started in a short period of time, the ammonia nitrogen removal effect is obvious, the simultaneous denitrification and partial organic matter and sulfate removal are realized;the subsequent denitrification step does not need a large amount of additional organic carbon or expensive chemical reagent, the overall cost is reduced;the process is simple to install, does not need large-scale modification of existing treatment device, and has broad prospects in wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of microbiology, and more specifically to a nitrogen-loving bacterium for wastewater treatment, its cultivation method, and its application. Background Technology

[0002] With the rapid development of industrial production, the discharge of high-ammonia nitrogen wastewater from industries such as chemical engineering, printing and dyeing, papermaking, aquaculture, and landfill leachate treatment is increasing daily. Ammonia nitrogen, as one of the major pollutants in water bodies, leads to eutrophication when discharged excessively, causing a series of environmental problems such as cyanobacterial blooms and decreased dissolved oxygen, seriously threatening the ecological environment and human health. Therefore, the effective treatment of high-ammonia nitrogen wastewater has become an important issue in the field of environmental protection.

[0003] Currently, wastewater denitrification mainly employs biological denitrification technology, the core of which is the conversion of ammonia nitrogen into nitrogen gas through microbial processes such as ammonia oxidation, nitrification, nitrification, and denitrification. Traditional biological denitrification processes rely on the synergistic effect of nitrifying and denitrifying bacteria, but they have several limitations: Firstly, nitrifying bacteria themselves grow slowly and are sensitive to environmental conditions, while high-sulfate wastewater is biotoxic, and their proliferation rate and bacterial activity are easily inhibited under high ammonia nitrogen and high sulfate concentrations. Secondly, traditional denitrification processes require a large amount of organic carbon as an electron donor. For high-ammonia nitrogen wastewater with low organic carbon content, additional organic carbon sources such as methanol and glucose need to be added, leading to a significant increase in treatment costs and a high risk of secondary pollution. Furthermore, traditional processes have long start-up cycles and require significant modifications to existing treatment equipment, limiting their application effectiveness in treating high-ammonia nitrogen wastewater.

[0004] CN107760622A discloses a strain of denitrifying paracoccus that can utilize elements such as organic carbon and ammonia nitrogen in high-ammonia nitrogen wastewater for growth, thereby reducing COD and ammonia nitrogen in the wastewater. However, this bacterium does not involve sulfate treatment. Removing high sulfate levels from industrial wastewater (such as mining, pharmaceutical, and papermaking wastewater) requires additional pretreatment using chemical precipitation methods (such as adding barium or calcium salts to generate barium sulfate / calcium sulfate precipitates) or membrane separation methods (such as reverse osmosis). Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a highly efficient nitrogen-loving bacterium that is tolerant to high ammonia nitrogen and high sulfate levels, adaptable to low organic carbon environments, and has strong process compatibility. This is of great significance for optimizing biological denitrification processes, reducing treatment costs, and improving the treatment effect of high ammonia nitrogen wastewater.

[0006] In a first aspect, the present invention provides a nitrogen-loving bacterium for wastewater treatment, wherein the nitrogen-loving bacterium is a member of the genus *Paracoccus*. Paracoccus sp.The nitrogen-loving bacterium HF-E2025009 was deposited on December 8, 2025, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with the strain number CGMCC No. 36935.

[0007] Furthermore, the azotrophic bacteria can maintain stable ammonia oxidation activity in an environment with an ammonia nitrogen concentration of 500 mg / L and can tolerate high sulfate environments.

[0008] Furthermore, the strain is able to efficiently convert ammonia nitrogen into NO2. - Under low-oxygen or hypoxic conditions, the strain will produce NO2 - It is further converted into nitrogen gas and can simultaneously remove some sulfates under low organic carbon conditions.

[0009] Furthermore, the strain is a facultative anaerobic / aerobic bacterium with an optimal growth pH of 6.9–7.6 (pH range of 6.8–8.5) and an optimal culture temperature of 30°C (temperature range of 25°C–36°C). Furthermore, the 16S rRNA gene sequence of the azotrophic bacterium is shown in SEQ ID NO. 1.

[0010] Furthermore, the strain can still effectively remove ammonia nitrogen and total nitrogen under one or more of the following conditions:

[0011] (a) Ammonia nitrogen concentration ≤ 500 mg / L;

[0012] (b) High sulfate tolerance ≤1500 mg / L;

[0013] (c) The temperature is 25℃~36℃;

[0014] (d) pH value is 6.8~8.5.

[0015] In a second aspect, the present invention provides a microbial culture comprising the aforementioned azotrophic bacteria and / or their fermentation metabolites.

[0016] In a third aspect, the present invention provides a microbial inoculant comprising an effective amount of the aforementioned azotrophic bacteria or the aforementioned microbial culture, and a carrier.

[0017] Furthermore, the bacterial agent is a freeze-dried powder, granules, or concentrated liquid; the carrier includes at least one of activated carbon, porous ceramics, polyvinyl alcohol gel, and diatomaceous earth.

[0018] Furthermore, the microbial agent also contains other functional microorganisms selected from at least one of nitrifying bacteria, denitrifying bacteria, and polyphosphate-accumulating bacteria.

[0019] In a fourth aspect, the present invention provides a wastewater treatment method, the method comprising adding an effective amount of the aforementioned azotrophic bacteria, or the aforementioned microbial culture, or the aforementioned microbial agent to the wastewater to be treated.

[0020] Further, the effective amount is 50~600ppm, and even further, the effective amount is 150~300ppm.

[0021] Furthermore, with the aforementioned azotrophic bacteria Paracoccus sp. With the increased dosage of HF-E2025009, the hydraulic retention time can be shortened from 72 hours to 12-48 hours, and the denitrification efficiency can be stabilized at 70%-80%.

[0022] Furthermore, the wastewater contains ammonia nitrogen, sulfate, and low carbon. Optionally, the type of wastewater is selected from at least one of domestic sewage, aquaculture wastewater, food processing wastewater, and landfill leachate.

[0023] Furthermore, the dosing step is carried out in anoxic, anaerobic, facultative, or aerobic tanks of the wastewater treatment system.

[0024] In a specific embodiment of the present invention, the wastewater treatment method is as follows:

[0025] (1) The wastewater to be treated is fed into an aerobic biological reactor containing nitrogen-loving bacteria, and the dissolved oxygen concentration is controlled so that ammonia nitrogen is converted into nitrite nitrogen under aerobic conditions;

[0026] (2) Introduce the effluent from step (1) into the anoxic reaction zone so that nitrite nitrogen is converted into nitrogen gas under anoxic conditions.

[0027] Furthermore, in step (1), the pH in the aerobic bioreactor is controlled to be 6.8~8.5 and the temperature to be 25~36℃.

[0028] Furthermore, the aforementioned azotrophic bacteria can efficiently convert ammonia nitrogen into NO2. - Under low-oxygen or hypoxic conditions, the strain will produce NO2 - The specific principle of further conversion into nitrogen gas is as follows:

[0029] (1) Add a small bioreactor to the front end of the existing biochemical tank, continuously add the expanded culture of the bacterial strain to the reactor, control the temperature in the reactor to 25℃-36℃ and the pH to 6.8~8.5, and maintain the activity of the bacterial strain;

[0030] (2) Wastewater with high ammonia nitrogen and high sulfate levels enters the biological reactor. The dissolved oxygen level in the reactor is controlled to ensure that the wastewater and the bacterial strains are in full contact under oxygenated conditions. The bacterial strains convert the ammonia nitrogen in the wastewater into NO2. -Meanwhile, the sulfate in the wastewater can be used as a nutrient source, and the growth and activity of the strain are basically unaffected, while the sulfate concentration in the system decreases synchronously.

[0031] (3) The effluent after treatment in the biological reactor enters the downstream low-oxygen or anoxic reaction zone, where the bacterial strains will release NO2 - It is further converted into nitrogen gas, thus achieving denitrification.

[0032] In a fifth aspect, the present invention provides the use of the aforementioned azotrophic bacteria, or the aforementioned microbial culture, or the aforementioned microbial inoculant in any of the following aspects:

[0033] A1. Application in the preparation of products for denitrification of wastewater;

[0034] A2. Application in the preparation of products for reducing the organic matter content in wastewater;

[0035] A3. Application in the preparation of products for reducing sulfate content in wastewater.

[0036] Furthermore, the application of the aforementioned azotrophic bacteria, or the aforementioned microbial culture, or the aforementioned microbial agent in wastewater treatment is provided.

[0037] In a sixth aspect, the present invention provides a wastewater treatment system, the system comprising a bioaugmentation module filled with biological packing material containing the nitrogen-loving bacteria, the microbial culture, or the microbial agent.

[0038] Furthermore, the system includes an aerobic bioreactor and an anoxic reaction zone connected in sequence, wherein the aerobic bioreactor contains the nitrogen-loving bacteria.

[0039] In a seventh aspect, the present invention provides a method for culturing the aforementioned azotrophic bacteria, the method comprising the following steps:

[0040] S1. Enrichment culture: The sample containing the azotrophic bacteria is inoculated into a liquid enrichment culture medium and cultured under aerobic shaking conditions to obtain the enrichment solution of the azotrophic bacteria;

[0041] S2. Separation and purification: Spread the enriched solution obtained in step S1 onto a solid culture medium, and after incubation, pick a single colony for purification.

[0042] S3. Expanded culture: The purified strain is inoculated into liquid culture medium for expanded culture.

[0043] Furthermore, in step S1, the liquid enrichment culture medium contains sulfate and ammonia nitrogen, and the conditions for the aerobic shaking culture are: temperature 25-36℃, rotation speed 150-250 rpm, and culture time 7-14 days.

[0044] Furthermore, the solid culture medium in step S2 is LB solid culture medium.

[0045] Further, the components per liter of the liquid enrichment solution are: ammonium chloride 50 mg, glucose 0.5 g, sodium acetate 0.2 g, sodium bicarbonate 0.5 g, potassium dihydrogen phosphate 0.5 g, magnesium sulfate heptahydrate 0.1 g, calcium chloride dihydrate 0.05 g, ferrous sulfate heptahydrate 0.01 g, and trace element solution: 1 mL (containing Mn, Zn, Cu, Co, Mo, Ni, etc.). The pH is adjusted to 7.0 ± 0.2.

[0046] Further, the expansion culture step in step S3 is as follows: pick a single colony from the plate and inoculate it into a test tube. Incubate overnight at 25-36°C and 150-250 rpm. Then, transfer the colony at a ratio of 1%-5% to a shake flask containing fresh liquid culture medium and continue culturing at 25-36°C and 150-250 rpm to obtain a nitrogenophilic bacterial suspension.

[0047] The beneficial effects of the present invention include, but are not limited to:

[0048] The azotrophic bacteria isolated for the first time in this invention Paracoccus sp. HF-E2025009, this strain maintains stable ammonia oxidation activity under high ammonia nitrogen and high sulfate conditions; the system can be started up in a short time, the ammonia nitrogen removal effect is significant, and the denitrification efficiency is comparable to that of chemical reagent methods; and the azotrophic bacteria described in this invention... Paracoccus sp. HF-E2025009 can also achieve simultaneous denitrification and removal of some organic matter and sulfates; subsequent denitrification steps do not require the addition of large amounts of external organic carbon or expensive chemical reagents, thus reducing overall costs; the process is simple to install and does not require large-scale modification of existing treatment equipment, and has broad prospects in wastewater treatment, especially industrial wastewater and livestock and poultry breeding wastewater.

[0049] The principle of ammonia nitrogen and sulfate removal by the nitrogenophilic bacteria described in this invention is as follows: High-ammonia nitrogen and high-sulfate wastewater comes into full contact with the bacterial strain under oxygenated conditions, and the strain converts the ammonia nitrogen in the wastewater into NO2. - Simultaneously, the sulfate in the wastewater can be used as a nutrient source, and the growth and activity of the strain are basically unaffected, with the sulfate concentration in the system decreasing synchronously; then, entering the downstream low-oxygen or anoxic reaction zone, the strain will utilize NO2 - It is further converted into nitrogen gas, achieving denitrification. The entire process is non-toxic and harmless, and will not cause secondary pollution to the environment. Attached Figure Description

[0050] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0051] Figure 1 The azotrophic bacteria in the embodiments of the present invention Paracoccus sp. Electron microscope image of HF-E2025009. Detailed Implementation

[0052] The present invention is described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments. Unless otherwise specified, the raw materials and catalysts in the embodiments of the present invention are all purchased through commercial channels.

[0053] Biomaterials:

[0054] Azotrophs HF-E2025009: Paracoccus Paracoccus sp. It was deposited on December 8, 2025, at the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with the strain number CGMCC No. 36935.

[0055] The components of LB medium per liter are as follows: 10g tryptone, 5g yeast extract, and 10g sodium chloride.

[0056] The components per liter of LB solid medium are as follows: 10g tryptone, 5g yeast extract, 10g sodium chloride, and 20g agar.

[0057] The liquid enrichment medium consists of the following components per liter: ammonium chloride 50 mg, glucose 0.5 g, sodium acetate 0.2 g, sodium bicarbonate 0.5 g, potassium dihydrogen phosphate 0.5 g, magnesium sulfate heptahydrate 0.1 g, calcium chloride dihydrate 0.05 g, ferrous sulfate heptahydrate 0.01 g, and trace element solution: 1 mL (containing Mn, Zn, Cu, Co, Mo, Ni). The pH is adjusted to 7.0 ± 0.2.

[0058] Unless otherwise specified, all pharmaceuticals and reagents mentioned in the examples are commercially available products.

[0059] Example 1: Nitrogenous Bacteria Paracoccus sp. Acquisition of HF-E2025009

[0060] 1. Sample collection: The strain described in this invention was obtained from Shandong Province, China.

[0061] 2. Enrichment culture: Sludge samples were inoculated into liquid enrichment culture medium and cultured aerobically at 30°C with shaking (200 rpm) for 10 consecutive days. Fresh culture medium was replaced every 2–3 days to screen for microbial populations with high ammonia nitrogen, high sulfate tolerance and ammonia oxidation activity.

[0062] 3. Isolation and purification: The enriched solution was serially diluted and spread onto LB agar plates, and incubated at 30°C for 3–5 days. Typical colonies were selected for three consecutive streak purifications to obtain a stable pure strain.

[0063] 4. Strain identification: Sequencing of the 16S rRNA gene (as shown in SEQ ID NO.1) and phylogenetic analysis revealed that this strain belongs to... Paracoccus genus, named Paracoccus sp. HF-E2025009. Paracoccus sp. HF-E2025009 has been deposited at the China General Microbiological Culture Collection Center (CGMCC) on December 8, 2025, with accession number CGMCC No. 36935.

[0064] SEQ ID NO.1:

[0065]

[0066] Example 2: Culture of azotrophic Paracoccus sp. HF-E2025009

[0067] The culture method for the azotrophic bacterium Paracoccus sp. HF-E2025009 is as follows:

[0068] Pick a single colony from the plate and inoculate it into a test tube. Incubate overnight at 30°C and 200 rpm. Then, transfer the colony at a ratio of 1% to a shake flask containing fresh liquid enrichment medium and continue incubation at 30°C and 200 rpm.

[0069] The obtained strain was examined by electron microscopy, and the electron microscope images are as follows: Figure 1 As shown.

[0070] Example 3: Nitrogenous bacteria Paracoccus sp. Application of HF-E2025009 in Industrial Wastewater Treatment

[0071] Comparative strain 1: Paracoccus denitrificans (Beijerinck and Minkman) Davisemend. Rainey et al. (ATCC 13543), purchased from the American Type Culture Collection, strain number: ATCC13543.

[0072] Comparative strain 2: Paracoccus homiensis CICC®10429, purchased from China Industrial Microbial Culture Collection Center, strain number CICC 10429.

[0073] The water quality conditions for papermaking wastewater are as follows: Wastewater generated from the production of grey-bottom white cardboard using domestic waste as raw material. The wastewater's various indicators are: ammonia nitrogen (NH4+)... + -N) 70~90mg / L, total nitrogen (TN) 100~120mg / L, sulfate (SO4²) - 600~800mg / L, chemical oxygen demand (COD) 800~1200mg / L, pH value 6.9~7.6.

[0074] The specific method is as follows: Papermaking wastewater enters the ammonia oxidation reactor, and nitrogen-loving bacteria are inoculated at a rate of 10%. Paracoccus sp. HF-E2025009, with moderate dissolved oxygen (1.5 mg / L), maintains high activity of the strain, which is capable of converting large amounts of ammonia nitrogen into NO2. - Simultaneously, the sulfate in the wastewater can be used as a nutrient source. Therefore, after a period of reaction, the ammonia nitrogen and sulfate content in the wastewater decreases significantly, with NO2 being the main product. -The effluent enters the downstream low-oxygen reaction zone. Under low-oxygen or anoxic conditions, the bacterial strains will produce NO2. - It is further converted into nitrogen gas to achieve denitrification. The effluent indicators are as follows: ammonia nitrogen 5~8 mg / L, total nitrogen 10~20 mg / L, sulfate 500~700 mg / L, COD 150~260 mg / L, ammonia nitrogen removal rate 80~90%, total nitrogen removal rate 75~85%, sulfate removal rate 10~15%, and COD removal rate 80~90%. This is the experimental group.

[0075] Meanwhile, control bacteria 1 and 2 were set up as positive control groups to treat high ammonia nitrogen, high sulfate, and low carbon wastewater in the same way, and control bacteria 2 were set up as negative control groups (blank control groups) to treat high ammonia nitrogen, high sulfate, and low carbon wastewater in the same way without adding any strains. Each group had three replicates.

[0076] Among them, the effluent indicators of the control bacteria 1 are as follows: ammonia nitrogen 15~20mg / L, total nitrogen 30~50mg / L, sulfate 600~800mg / L, COD 300~400mg / L, ammonia nitrogen removal rate 60~80%, total nitrogen removal rate 50~70%, sulfate removal rate almost zero, and COD removal rate 60~75%.

[0077] The effluent parameters of the control bacteria 2 were as follows: ammonia nitrogen 35~40mg / L, total nitrogen 50~70mg / L, sulfate 600~800mg / L, COD 450~600mg / L, ammonia nitrogen removal rate 40~50%, total nitrogen removal rate 40~60%, sulfate removal rate almost zero, and COD removal rate 30~55%.

[0078] The effluent parameters of the blank control group were: ammonia nitrogen 70~90mg / L, total nitrogen 100~120mg / L, sulfate 600~800mg / L, and COD 800~1200mg / L.

[0079] Table 1. Application results of different nitrogen-loving bacteria in wastewater treatment

[0080]

[0081] As can be seen from the comparison results in Table 1, the azotrophic bacteria provided by this invention... Paracoccus sp. HF-E2025009 exhibits stronger removal efficiency than other azotrophic bacteria, can survive in environments with sulfate concentrations of 1200~1500 mg / L, and demonstrates stable removal efficiency for ammonia nitrogen and total nitrogen, significantly outperforming existing azotrophic bacteria and improving wastewater treatment efficiency.

[0082] Example 4: Azotrophic bacteria Paracoccus sp. HF-E2025009: Artificially Prepared Simulated Livestock and Poultry Farming Wastewater Treatment Experiment

[0083] Simulated livestock and poultry farm wastewater was artificially prepared (ammonia nitrogen content adjusted to 400-500 mg / L with ammonium chloride, COD provided by a mixture of glucose and sodium acetate to approximately 2000 mg / L, sodium sulfate added to achieve a sulfate concentration of 1500 mg / L, pH 6.9-7.6), and dispensed into 500 mL Erlenmeyer flasks, each with a liquid volume of 200 mL. The flasks were then inoculated and cultured overnight. Paracoccus sp. HF-E2025009 (Initial OD) 600 ≈0.2) and existing azotrophs (initial OD) 600 (≈0.2), cultured at 30℃ and 200 rpm on a shaker, and artificially prepared simulated wastewater treatment results. Paracoccus sp. Table 2 shows a comparison of HF-E2025009 (Ⅰ), control bacteria 1 (Ⅱ), and control bacteria 2 (Ⅲ); inoculated and cultured overnight. Paracoccus sp. HF-E2025009 was cultured at 30℃ and 200 rpm on a shaker for 12-48 h. Paracoccus sp. Different dosages of HF-E2025009 (50ppm, 150ppm, 300ppm, 600ppm) were applied in two replicates per group. The results are shown in Table 3.

[0084] Table 2. Experimental results of different azotrophic bacteria on the treatment of livestock and poultry breeding wastewater

[0085]

[0086] Table 3. Nitrogenous bacteria at different dosages Paracoccus sp. Experimental results of HF-E2025009 on the treatment of livestock and poultry breeding wastewater

[0087]

[0088] As shown in Table 2, samples were taken every 24 hours during the experiment to detect TN and NH4. + -N, while simultaneously monitoring COD and sulfate. Results showed: azotrophic bacteria. Paracoccus sp. Within 72 hours, HF-E2025009 achieved ammonia nitrogen removal rates of 82.2%, TN removal rates of 76%, and COD removal rates of 82%, significantly higher than control bacteria 1 and 2. Particularly noteworthy was its sulfate removal rate, which reached 11%, while control bacteria 1 and 2 showed no significant sulfate removal efficiency. These results indicate... Paracoccus sp. HF-E2025009 can achieve simultaneous denitrification and partial removal of organic matter and sulfate under conditions of high ammonia nitrogen, high sulfate, and low carbon, and its removal efficiency is higher than that of existing azotrophic bacteria of the Paracoccus genus. At the same time, as the dosage of Paracoccus sp. HF-E2025009 increases (50-600ppm), the hydraulic retention time does not need to be 72h, but can be shortened to 12-48h, and the denitrification efficiency remains stable at 70%-80%.

[0089] Example 5: Nitrogenophilic bacteria Paracoccus sp. Comparison of the effects of HF-E2025009 with ordinary denitrifying bacteria and chemical reagents

[0090] The effects of azotrophic Paracoccus sp. HF-E2025009 on common denitrifying bacteria and chemical reagents are compared in Table 4.

[0091] Table 4. Comparison of the effects of azotrophic Paracoccus sp. HF-E2025009 with common denitrifying bacteria and chemical reagents.

[0092]

[0093] The above description is merely an embodiment of the present invention, and the scope of protection of the present invention is not limited to these specific embodiments, but is determined by the claims of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principle of the present invention should be included within the scope of protection of the present invention.

Claims

1. A nitrogen-loving bacterium for wastewater treatment, characterized in that, The azotrophic bacteria are of the genus *Paracoccus*. Paracoccus sp. The nitrogen-loving bacterium HF-E2025009 was deposited at the China General Microbiological Culture Collection Center on December 8, 2025, with accession number CGMCC No. 36935.

2. A microbial culture, characterized in that, The culture comprises the azotrophic bacteria as described in claim 1.

3. A microbial inoculant, characterized in that, The mixture comprises an effective amount of the azotrophic bacteria of claim 1 or the microbial culture of claim 2, and a carrier.

4. The microbial agent according to claim 3, characterized in that, The bacterial agent is a freeze-dried powder, granules, or concentrated liquid; the carrier includes at least one of activated carbon, porous ceramics, polyvinyl alcohol gel, and diatomaceous earth.

5. The microbial agent as described in claim 4, characterized in that, The microbial agent also contains other functional microorganisms selected from at least one of nitrifying bacteria, denitrifying bacteria, and polyphosphate-accumulating bacteria.

6. A wastewater treatment method, characterized in that, The method includes adding an effective amount of the nitrogen-loving bacteria as described in claim 1, or the microbial culture as described in claim 2, or the microbial agent as described in any one of claims 3-5 to the wastewater to be treated.

7. The method according to claim 6, characterized in that, The effective amount is 50~600ppm.

8. The method as described in claim 6, characterized in that, The type of wastewater is selected from at least one of domestic sewage, aquaculture wastewater, food processing wastewater, and landfill leachate.

9. The use of the azotrophic bacteria of claim 1, or the microbial culture of claim 2, or the microbial agent of any one of claims 3-5 in any of the following aspects: A1. Application in the preparation of products for denitrification of wastewater; A2. Application in the preparation of products for reducing the organic matter content in wastewater; A3. Application in the preparation of products for reducing sulfate content in wastewater.

10. A wastewater treatment system, characterized in that, The system includes a bio-enhancing module, which is filled with a biological filler containing the azotrophic bacteria of claim 1, the microbial culture of claim 2, or the microbial agent of any one of claims 3-5.

Images