A method for treating pig farm wastewater using direct ammonia-oxidizing bacteria

Abstract

This invention belongs to the field of high-concentration wastewater treatment technology and discloses a method for treating pig farm wastewater using direct ammonia oxidizing bacteria. The method includes: reviving and activating direct ammonia oxidizing bacteria; cultivating direct ammonia oxidizing bacteria; treating actual pig farm wastewater with direct ammonia oxidizing bacteria; and starting an MBR reactor using direct ammonia oxidizing bacteria as inoculum and simulated pig farm wastewater as influent. This invention aims to provide a method for directly treating pig farm wastewater using ammonia oxidation. This method has strong tolerance to high concentrations of ammonia nitrogen, exhibits good denitrification performance, and simplifies the process flow while reducing operating costs.

Description

Technical Field

[0001] This invention relates to the field of livestock and poultry breeding wastewater treatment technology, specifically to a method for treating pig farm wastewater using direct ammonia-oxidizing bacteria. Background Technology

[0002] With the adjustment of my country's rural industrial structure, livestock and poultry farming, especially pig farming, has developed rapidly. However, this has also led to the generation of large amounts of pig farm wastewater, placing immense pressure on the ecological environment. Pig farm wastewater mainly consists of animal excrement, urine, feed residue, and pens flushing water. It is characterized by high and fluctuating concentrations of organic pollutants, nitrogenous substances, and suspended solids. Improper treatment of pig farm wastewater and the release of its pollutants into the environment can damage water bodies, soil, and air, threatening the health of animals and humans. Therefore, in order to protect the ecological environment and reduce pollution, denitrification technology for pig farm wastewater is extremely important.

[0003] Domestically and internationally, the treatment of pig farm wastewater typically employs physicochemical methods as pretreatment processes, followed by secondary biological treatment using a combination of anaerobic, anoxic, and aerobic processes. The challenges in treating pig farm wastewater lie in the inhibitory effect of high concentrations of ammonia nitrogen on microbial growth, as well as the excessively long process flow and high operating costs of traditional wastewater treatment methods. Therefore, the sustainable development and environmental protection of the pig farming industry urgently require a highly efficient and low-carbon method for treating pig farm wastewater. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, and addressing the problems of high-concentration ammonia nitrogen inhibition and excessively long and costly traditional wastewater treatment processes, this invention aims to provide a method for treating pig farm wastewater using direct ammonia-oxidizing bacteria. This method exhibits strong tolerance to high concentrations of ammonia nitrogen, excellent denitrification performance, and simplifies the process while reducing operating costs.

[0005] The above-mentioned objective of this invention is achieved through the following technical solution:

[0006] A method for treating pig farm wastewater using direct ammonia oxidizing bacteria includes: reviving and activating a strain with direct ammonia oxidizing function; growing and culturing the strain with direct ammonia oxidizing function; directly oxidizing actual pig farm wastewater; and starting an MBR reactor using the strain with direct ammonia oxidizing function as inoculum and simulated pig farm wastewater as influent.

[0007] Furthermore, the strain with direct ammonia oxidation function was obtained by purchasing *Alkalobacterium fecalis* subsp. *fecalis*, numbered CGMCC1.1837, from the China General Microbiological Culture Collection Center (CGMCC). This strain has direct ammonia oxidation function.

[0008] Furthermore, the resuscitation and activation of the strain with direct ammonia oxidation function is specifically performed as follows: A nutrient broth agar medium is prepared with the following components: 5.0 g peptone, 3.0 g beef extract, 5.0 g NaCl, 1000 ml distilled water, and pH 7.0-7.5. The above medium is sterilized at 121-126℃ for 20-30 min. The purchased strain CGMCC1.1837 is then transferred to the above medium on a clean bench for strain reactivation.

[0009] Furthermore, the culture conditions for the growth and culture of the strain with direct ammonia oxidation function are as follows: ammonia nitrogen concentration of 400-3000 mg / L, C / N ratio of 5-20, salinity of 0.0%-2.0%, pH of 7.0-9.0, carbon source of CH3COONa, and temperature of 29.5-30.5℃.

[0010] Furthermore, the direct ammonia oxidation treatment of actual pig farm wastewater is as follows: The pig farm wastewater is untreated raw water from a pig farm in Shandong. The obtained pig farm wastewater is filtered, and the filtered pig farm wastewater is sterilized at 121-126℃ for 20-30 min. The above-mentioned strain CGMCC1.1837 is inoculated on an ultra-clean workbench, sealed with sealing film, and three parallel processes are set up.

[0011] Furthermore, the actual pig farm wastewater after inoculation was placed in a constant temperature shaker. The constant temperature shaking conditions were: a temperature of 29.5-30.5℃, a rotation speed of 150-160 rpm, a cycle of 7-9 days, and water quality measurements were taken every 23-24 hours.

[0012] Furthermore, the MBR reactor influent was designed to simulate pig farm wastewater, using (NH4)2SO4 as the nitrogen source and CH3COONa as the carbon source. During the start-up and operation phase of the MBR reactor, the water quality was as follows: NH4... + -N concentration is 1000-1500 mg / L, and COD concentration is 7000-10000 mg / L.

[0013] As a further step, during the start-up of the MBR reactor, CGMCC1.1837 was used as the inoculum, with the CGMCC1.1837 bacterial culture concentration OD... 600 The concentration of CGMCC 1.1837 bacterial solution was 1.7536, and the volume ratio of the simulated pig farm wastewater to the total bacterial concentration was 1 / 25. The reaction temperature was maintained at 29-31℃ via a water bath heating layer. The MBR reactor was operated under aeration conditions, providing oxygen to maintain bacterial activity and carrier movement. The aeration rate was controlled at 1.0-1.8 L / min using a flow meter. The hydraulic retention time (HRT) was set to 4-6 days, when NH4+... +The stabilization of N2 and COD removal and the formation of a stable biofilm on the support indicate that the MBR reactor has been successfully started up.

[0014] This invention also claims protection for the application of the above-described method for treating pig farm wastewater using direct ammonia-oxidizing bacteria in the treatment of pig farming wastewater.

[0015] The beneficial effects of this invention compared to the prior art are:

[0016] Compared with existing pig farm wastewater treatment technologies, the advantages of this invention are: 1) The growth rate of strains with direct ammonia oxidation function is significantly higher than that of autotrophic nitrifying bacteria, making them easier to proliferate and accumulate; 2) They can maintain high activity within a pH range of 7-10; 3) They eliminate the need for anaerobic or anoxic stages, greatly simplifying the process, significantly reducing space requirements, and lowering operating costs; 4) They have strong tolerance to high ammonia nitrogen levels in pig farm wastewater; 5) They can maintain high activity within a wide C / N ratio range (5-20), effectively performing simultaneous nitrogen and carbon removal from pig farm wastewater. Attached Figure Description

[0017] Figure 1 A graph showing the performance comparison results of four strains with direct ammonia oxidation function; Figure 1 a represents the denitrification effect of the four strains within 48 hours; Figure 1 b shows the growth of the four strains over 48 hours.

[0018] Figure 2 The flowchart for the growth and culture of CGMCC1.1837.

[0019] Figure 3 Figure 1 shows the effect of CGMCC1.1837 in treating actual pig farm wastewater. Figure 2 shows the denitrification efficiency of CGMCC1.1837 in treating actual pig farm wastewater. Figure 3 shows the carbon removal effect of CGMCC1.1837 in treating actual pig farm wastewater.

[0020] Figure 4 This is a schematic diagram of an MBR reactor.

[0021] In the diagram: 1. Constant temperature water tank; 2. First inlet pump; 3. MBR reaction tank; 4. Agitator motor; 5. Agitator blades; 6. Aeration head; 7. Second inlet pump; 8. Inlet tank. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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. Unless otherwise specified, the equipment and reagents used in the present invention are commercially available products conventional in this technical field.

[0023] The term "comprising" and its variations, as used in this invention, indicate open inclusion, meaning "including but not limited to". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0024] This embodiment provides a method for treating pig farm wastewater using a strain with direct ammonia oxidation function, comprising: reviving and activating the strain with direct ammonia oxidation function; growing and culturing the strain with direct ammonia oxidation function; directly treating actual pig farm wastewater with ammonia oxidation function; and starting an MBR reactor using the strain with direct ammonia oxidation function as inoculum and simulated pig farm wastewater as influent. Example

[0025] (1) Resuscitation and activation of strains with direct ammonia oxidation function

[0026] *Alcaligenes faecalis* subsp. *fecalisinica*, strain number CGMCC1.1837, was purchased from the China General Microbiological Culture Collection Center (CGMCC). This strain possesses direct ammonia oxidation function. The method for reviving and activating strains with direct ammonia oxidation function was as follows: Nutrient broth agar medium was prepared according to the instructions provided by the Culture Collection Center, with the following components: 5.0 g peptone, 3.0 g beef extract, 5.0 g NaCl, 1000 ml distilled water, pH 7.0-7.5. The medium was sterilized at 121℃ for 30 min. The purchased strain CGMCC1.1837 was then transferred to the above medium on a clean bench for revival.

[0027] (2) Growth and culture of strains with direct ammonia oxidation function

[0028] The strain CGMCC1.1837 was cultured under the following conditions: ammonia nitrogen concentration of 500 mg / L, C / N ratio of 10, salinity of 0.2%, pH of 7.0, carbon source of CH3COONa, and temperature of 30 ℃. The specific culture process is as follows:

[0029] S1: Culture medium / L: (NH4)2SO4 2.36 g, CH3COONa 6.41 g, KH2PO4 0.44 g, MgSO4·7H2O 0.2 g, NaCl 2 g, trace elements 2.00 ml, pH 7.0. Take 100 ml of this culture base and place it in a 250 ml Erlenmeyer flask, seal with sealing film, and set up three replicates per group. Sterilize in an autoclave at 121 ℃ for 30 minutes.

[0030] S2: Once the temperature of the high-pressure steam sterilizer in step S1 has decreased to approximately 30°C, remove the culture medium from the sterilizer and place it on the laminar flow hood. Turn on the ultraviolet (UV) sterilization lamp and sterilize the inside of the laminar flow hood for 30 minutes. Turn on the air supply switch of the laminar flow hood and inoculate 1 ml of CGMCC1.1837 bacterial suspension into the above culture medium, wherein the bacterial suspension concentration is OD0.05. 600 It is 2.0232.

[0031] S3: Place the culture medium inoculated with CGMCC1.1837 from step S2 into a constant temperature shaker at 30℃ and 150 rpm. The culture period is 4 days, with samples taken every 24 hours on a clean bench to determine water quality parameters.

[0032] (3) Direct ammonia oxidation treatment of actual pig farm wastewater

[0033] The pig farm wastewater was taken from untreated raw water of a pig farm in Shandong Province. The basic water quality indicators of this raw wastewater were: ammonia nitrogen 1200-1500 mg / L, total nitrogen 1300-1600 mg / L, COD 8000-8500 mg / L, and pH 7.4-7.6. The wastewater was treated by vacuum filtration through a 0.45µm aqueous microporous membrane. The treated wastewater was dark brown and free of other impurities. Vacuum filtration effectively removed most of the suspended solids. 100 ml of the filtered wastewater was divided into three 250 ml Erlenmeyer flasks and sterilized at 121°C for 30 minutes. 2 ml of the aforementioned CGMCC1.1837 bacterial solution was inoculated into the sterilized wastewater. The bacterial concentration (OD) was... 600 The concentration was 1.9286. The sample was sealed with sealing film and placed in a constant-temperature shaker for incubation. The incubation temperature was 30℃, the rotation speed was 150 rpm, and the cycle was 8 days, with water quality indicators measured every 24 hours. The concentrations of ammonia nitrogen and COD in the wastewater were measured to determine the denitrification effect.

[0034] Depend on Figure 3 It can be seen that direct ammonia oxidation can achieve efficient nitrogen and carbon removal from pig farm wastewater, with an ammonia nitrogen removal rate of 84.16% and a total organic carbon removal rate of 89.6%.

[0035] (4) Start the MBR reactor using strains with direct ammonia oxidation function as inoculum.

[0036] Wastewater treatment was carried out in a cylindrical MBR reactor made of plexiglass, 30 cm high and 12 cm in diameter, with an effective volume of 3.0 L. Figure 4 As shown, the MBR reactor includes: a constant temperature water tank, a first inlet pump, an MBR reaction tank, a stirring motor, stirring blades, an aeration head, a second inlet pump, and an inlet tank. The constant temperature water tank, the first inlet pump, the MBR reaction tank, the second inlet pump, and the inlet tank are connected sequentially. The stirring motor, stirring blades, and aeration heads are connected to the MBR reaction tank. The stirring motor is located at the top of the MBR reaction tank, the stirring blades are located inside the MBR reaction tank, and the aeration heads are located at the bottom of the MBR reaction tank. The top of the stirring blades is connected to the stirring motor.

[0037] The constant temperature water tank 1 continuously supplies water to the water bath insulation layer of the MBR reactor 3 through the first water supply pump 2, controlling the temperature inside the MBR reactor to remain constant. The simulated pig farm wastewater in the inlet tank 8 enters the MBR reactor 3 under the action of the second inlet pump 7, where it is fully mixed with CGMCC1.1837 under the action of the stirring blades 5. Two aeration heads 6 are installed at the bottom of the MBR reactor to provide dissolved oxygen (DO) to the MBR reactor.

[0038] The MBR reactor influent was designed to simulate pig farm wastewater, using (NH4)2SO4 as the nitrogen source and CH3COONa as the carbon source. During the start-up and operation phase of the MBR reactor, the water quality was as follows: NH4... + -N concentration was 1000-1500 mg / L, and COD concentration was 7000-10000 mg / L. During the start-up of the MBR reactor, CGMCC1.1837 was used as the inoculum, with the CGMCC1.1837 bacterial culture concentration (OD) being... 600 The concentration of CGMCC 1.1837 bacterial solution was 1.7536, and the volume ratio of the simulated pig farm wastewater to the total bacterial concentration was 1 / 25. The reaction temperature was maintained at 30°C via a water bath heating layer. The MBR reactor was operated under aeration conditions, providing oxygen to maintain bacterial activity and carrier movement. The aeration rate was controlled at 1.0-1.8 L / min using a flow meter. The hydraulic retention time (HRT) was set to 5 days. OD was monitored periodically. 600 MLSS, TN removal rate, COD removal rate and NH4 + -N removal rate, when NH4 + The stabilization of N2 and COD removal and the formation of a stable biofilm on the support indicate that the MBR reactor has been successfully started up. Example

[0039] In step (2), the strain CGMCC1.1837 was cultured to produce ammonia nitrogen at a concentration of 400 mg / L, with other conditions the same as in Example 1. Example

[0040] In step (2), the strain CGMCC1.1837 was cultured to produce ammonia nitrogen at a concentration of 600 mg / L, with other conditions the same as in Example 1. Example

[0041] In step (2), the strain CGMCC1.1837 was cultured to produce ammonia nitrogen at a concentration of 800 mg / L, with other conditions the same as in Example 1. Example

[0042] In step (2), the strain CGMCC1.1837 was cultured to produce ammonia nitrogen at a concentration of 1000 mg / L, with other conditions the same as in Example 1. Example

[0043] In step (2), the strain CGMCC1.1837 was cultured for growth. The ammonia nitrogen concentration was 1500 mg / L, and the other conditions were the same as in Example 1. Example

[0044] In step (2), the strain CGMCC1.1837 was cultured to produce ammonia nitrogen at a concentration of 2000 mg / L, with other conditions the same as in Example 1. Example

[0045] In step (2), the strain CGMCC1.1837 was cultured to produce ammonia nitrogen at a concentration of 3000 mg / L, with other conditions the same as in Example 1. Example

[0046] In step (2), the strain CGMCC1.1837 was cultured for growth. The C / N ratio was 5, and the other conditions were the same as in Example 1. Example

[0047] In step (2), the strain CGMCC1.1837 was cultured for growth in the strain with direct ammonia oxidation function. The culture conditions were: C / N ratio of 20, and other conditions were the same as in Example 1. Example

[0048] In step (2), the strain CGMCC1.1837 was cultured for growth under the following conditions: salinity of 0.0% and other conditions were the same as in Example 1. Example

[0049] In step (2), the strain CGMCC1.1837 was cultured for growth under the following conditions: salinity of 0.4% and other conditions were the same as in Example 1. Example

[0050] In step (2), the strain CGMCC1.1837 was cultured for growth under the following conditions: salinity of 0.6% and other conditions were the same as in Example 1. Example

[0051] In step (2), the strain CGMCC1.1837 was cultured for growth under the following conditions: salinity of 0.8% and other conditions were the same as in Example 1. Example

[0052] In step (2), the strain CGMCC1.1837 was cultured for growth under the following conditions: salinity of 1.0% and other conditions were the same as in Example 1. Example

[0053] In step (2), the strain CGMCC1.1837 was cultured for growth under the following conditions: salinity of 2.0% and other conditions were the same as in Example 1. Example

[0054] In step (2), the strain CGMCC1.1837 was cultured for growth under the following conditions: pH 7.0, and other conditions were the same as in Example 1. Example

[0055] In step (2), the strain CGMCC1.1837 was cultured for growth under the following conditions: pH 8.0, and other conditions were the same as in Example 1. Example

[0056] In step (2), the strain CGMCC1.1837 was cultured for growth in the culture conditions of the strain with direct ammonia oxidation function. The pH was 9.0 and the other conditions were the same as in Example 1.

[0057] Comparative Example 1

[0058] In step S1, the strain with direct ammonia oxidation function was selected for resuscitation and activation. This strain was purchased from the China General Microbiological Culture Collection Center (CGMCC) as *Alkalobacterium fecesense* subsp. *fecesense*, with the serial number CGMCC1.2098. The rest of the steps were the same as in step S1 of Example 1.

[0059] Comparative Example 2

[0060] In step S1, the strain with direct ammonia oxidation function was selected for resuscitation and activation. The strain was purchased from the China General Microbiological Culture Collection Center (CGMCC) as an alkali-producing bacterium, with the number CGMCC1.9053. The rest of the steps were the same as in step S1 of Example 1.

[0061] Comparative Example 3

[0062] In step S1, the strain with direct ammonia oxidation function was selected for resuscitation and activation. This strain, *Alcaligenes faecalis*, was purchased from the China Industrial Microbial Culture Collection Center (CICC) and its catalog number was CICC23439. The rest of the steps were the same as in step S1 of Example 1.

[0063] Comparative Example 4

[0064] In step (2), the strain CGMCC1.1837 was cultured to produce ammonia nitrogen at a concentration of 3500 mg / L, with other conditions the same as in Example 1.

[0065] Comparative Example 5

[0066] In step (2), the strain CGMCC1.1837 was cultured for growth. The ammonia nitrogen concentration was 4000 mg / L, and the other conditions were the same as in Example 1.

[0067] Comparative Example 6

[0068] In step (2), the strain CGMCC1.1837 was cultured to produce ammonia nitrogen at a concentration of 5000 mg / L, with other conditions the same as in Example 1.

[0069] Comparative Example 7

[0070] In step (2), the strain CGMCC1.1837 was cultured to grow the strain with direct ammonia oxidation function. The culture conditions were: C / N = 1, and the others were the same as in Example 1.

[0071] Comparative Example 8

[0072] In step (2), the strain CGMCC1.1837 was cultured for growth. The C / N ratio was 2.5, and the other conditions were the same as in Example 1.

[0073] Comparative Example 9

[0074] In step (2), the strain CGMCC1.1837 was cultured for growth under the following conditions: salinity of 3.0% and other conditions were the same as in Example 1.

[0075] Comparative Example 10

[0076] In step (2), the strain CGMCC1.1837 was cultured for growth in the culture conditions of the strain with direct ammonia oxidation function. The pH was 5 and the other conditions were the same as in Example 1.

[0077] Comparative Example 11

[0078] In step (2), the strain CGMCC1.1837 was cultured for growth under the following conditions: pH 6, and other conditions were the same as in Example 1.

[0079] Comparative Example 12

[0080] In step (2), the strain CGMCC1.1837 was cultured to produce a direct ammonia oxidation strain. The carbon source was glucose, the ammonia nitrogen concentration was 140 mg / L, and the other conditions were the same as in Example 1.

[0081] Comparative Example 13

[0082] In step (2), the strain CGMCC1.1837 was cultured to produce a direct ammonia oxidation strain. The carbon source was starch, the ammonia nitrogen concentration was 140 mg / L, and the other conditions were the same as in Example 1.

[0083] Performance study of strains with direct ammonia oxidation function: Performance studies were conducted on the reactivated strains of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3; Heterotrophic nitrification medium (HNM / L) was prepared: (NH4)2SO4 0.66 g, CH3COONa 9.44 g, KH2PO4 0.5 g, MgSO4·7H2O 1.25 g, NaCl 10.0 g, and trace elements 2.00 ml (trace elements: EDTA). . 2Na 57.10 g, ZnSO4 . 3.90 g of 7H₂O and CaCl₂ .2H2O 7.00 g, MnCl2.4H2O 1.00g, FeSO4 . 7H2O 5.00 g, (NH4)6Mo7O 24 . 1.10 g of 4H₂O and CuSO₄ . 5H₂O 1.60 g, CoCl₂ . 1.60 g of 6H2O (pH 6.0, pH 7.0-7.5) was added. 100 ml of culture medium was placed in a 250 ml Erlenmeyer flask and sterilized at 121-126℃ for 30 min. 1 ml of bacterial suspension from each of the four revived strains (Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3) was inoculated into the culture medium. The initial OD of the culture medium was... 600 The values ​​were all around 0.03. The containers were sealed with sealing film, and three parallel samples were set up for each group, all placed in a constant-temperature shaker. The temperature was 30 ℃, the rotation speed was 150 rpm, the cycle was 2 days, and water quality indicators were measured every 24 hours, including the OD value of the bacterial solution. 600 The value is used to determine the bacterial growth status, and at the same time, the concentration of ammonia nitrogen in the wastewater is measured to determine the denitrification effect.

[0084] Depend on Figure 1 As can be seen from this, strain CGMCC1.1837 can achieve a removal efficiency of 73.41% within 24 hours, and can completely remove ammonia nitrogen from the culture medium within 48 hours. Furthermore, from... Figure 1 As shown in b, after 48 hours of cultivation, the bacterial concentration of CGMCC1.1837 was significantly higher than that of other strains in the treatment group, indicating that this strain has excellent proliferation ability. Therefore, CGMCC1.1837 exhibited good denitrification performance throughout the process.

[0085] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made to the invention. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for treating pig farm wastewater using direct ammonia-oxidizing bacteria, characterized in that, include: Resuscitation and activation of direct ammonia-oxidizing bacteria; Growth culture of direct ammonia oxidizing bacteria; Direct ammonia-oxidizing bacteria treatment of actual pig farm wastewater; The MBR reactor was started using direct ammonia oxidizing bacteria as inoculum and simulated pig farm wastewater as influent. The resuscitation and activation of the direct ammonia oxidizing bacteria is specifically as follows: Prepare a culture medium: 0002 nutrient broth agar, with the following specific components: 5.0 g peptone, 3.0 g beef extract, 5.0 g NaCl, 1000 ml distilled water, pH 7.0-7.5; sterilize the above components at 121-126℃ for 20-30 min on a clean bench, and transfer strain CGMCC1.1837 to the above culture medium for strain resuscitation.

2. The method for treating pig farm wastewater using direct ammonia-oxidizing bacteria as described in claim 1, characterized in that, The growth conditions for the direct ammonia oxidizing bacteria are as follows: ammonia nitrogen concentration of 500-600 mg / L, C / N ratio of 8-10, salinity of 0.2%-0.3%, pH of 7.0-7.5, carbon source of CH3COONa, and temperature of 29.5-30.5 ℃.

3. The method for treating pig farm wastewater using direct ammonia-oxidizing bacteria as described in claim 1, characterized in that, The specific steps for treating actual pig farm wastewater with direct ammonia oxidizing bacteria are as follows: the obtained pig farm wastewater is filtered, and the filtered pig farm wastewater is sterilized at 121-126 ℃ for 20-30 min. The above-mentioned direct ammonia oxidizing strain CGMCC1.1837 is then inoculated on an ultra-clean workbench and sealed with sealing film.

4. The method for treating pig farm wastewater using direct ammonia-oxidizing bacteria as described in claim 1, characterized in that, The wastewater from the inoculated pig farm was placed in a constant temperature shaker; The isothermal oscillation conditions were as follows: temperature incubation temperature 29.5-30.5℃, rotation speed 150-160 rpm, and cycle 7-9 days.

5. A method for treating pig farm wastewater using direct ammonia-oxidizing bacteria as described in claim 1, characterized in that MB The BR reactor feedwater was designed to simulate pig farm wastewater, with (NH4)2SO4 as the nitrogen source, CH3COONa as the carbon source, K2HPO4 as the phosphorus source, and CGMCC1.1837, a direct ammonia oxidizing bacterium, as the inoculum.

6. The application of the method for treating pig farm wastewater using direct ammonia-oxidizing bacteria as described in any one of claims 1-5 in the treatment of pig farm wastewater.

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