Efficient denitrification sewage treatment method

Abstract

The invention discloses a sewage treatment method for efficient denitrification. The sewage treatment method comprises the following steps: pretreatment and water quality homogenization; carrying out anaerobic ammonium oxidation bacterium inoculation and initial culture; nitrogen source fluctuation domestication; continuous water feeding domestication; preliminarily degrading ammonia nitrogen in an anaerobic tank; denitrifying in an anoxic tank; nitrifying in an aerobic tank, and carrying out solid-liquid separation in a secondary sedimentation tank. The method has the advantages that the directionally domesticated anaerobic ammonium oxidation bacteria are combined with the cold-resistant compound bacteria, so that the low-temperature adaptability and the nitrogen source fluctuation tolerance are considered; the fluctuation characteristic of actual sewage is simulated in the domestication stage, so that the strain adapts in advance; and through the cooperation of the endogenous denitrification tank and the anaerobic tank, the addition of a carbon source is reduced, and the operation cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the sewage treatment technical field, especially to sewage denitrification technology. BACKGROUND

[0002] Sewage denitrification is an important project for environmental governance. Although many denitrification technologies have been applied to sewage denitrification process, different treatment technologies have their own shortcomings. The chemical denitrification technology has high reagent cost and large sludge production. Chemical denitrification (such as breakpoint chlorination method, ion exchange method) needs to add a large amount of chlorine reagent or adsorbent (such as activated carbon), which has high operation cost and produces waste containing high concentration of salt or chemical sludge, increasing the difficulty of subsequent disposal. In addition, the chemical denitrification has narrow application range, and the chemical method has low treatment efficiency for low concentration of nitrogen, such as total nitrogen < 50 mg / L, and is easily interfered by other ions in water, such as Cl⁻ and SO4²⁻, which is more suitable for pretreatment of high-concentration industrial wastewater rather than deep denitrification of municipal sewage.

[0003] Biological denitrification has low dependence on reagents compared with chemical denitrification, and has been paid more and more attention in recent years. However, biological denitrification technology also has its shortcomings that cannot be ignored. Biological denitrification relies on the synergistic effect of nitrifying bacteria (aerobic) and denitrifying bacteria (anaerobic). Nitrifying bacteria have high requirements for temperature, and the optimum temperature is 20-30℃, and the activity decreases sharply at low temperature, which leads to a significant decrease in denitrification efficiency at low temperature. Nitrite accumulation may occur in the denitrification process, such as improper DO control and insufficient carbon source, which leads to excessive nitrite nitrogen in the effluent.

[0004] If a sewage denitrification technology that can adapt to low-temperature water quality and reduce nitrite accumulation can be developed, it will have great application prospect. SUMMARY

[0005] The present application aims to provide a sewage treatment method with high-efficiency denitrification, to solve the problems of limited denitrification effect, high treatment cost, complex process, and environmental protection in the prior art.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] A sewage treatment method with high-efficiency denitrification, comprising the following steps:

[0008] (1) Pretreatment and water quality homogenization: after the physical removal of large particle suspended solids, the sewage enters the adjusting tank, the water quality is stabilized, the pH of the sewage is 7.0-7.5, and the water temperature is maintained at 6-12℃;

[0009] (2) Prepare the acclimation medium, and pump the acclimation medium into the reaction tank: the acclimation medium includes NH4Cl 0.1-0.2 g, NaNO2 0.1-0.3 g, KH2PO4 0.05 g, MgSO4·7H2O 0.2 g, CaCl2 0.1 g, 10 mL trace element mother liquor, and 10% HCl solution or NaOH solution is used to adjust the pH to 7.2±0.1 in a volume of 1 L;

[0010] (3) Anaerobic ammonia oxidation bacteria inoculation and initial culture: anaerobic ammonia oxidation bacteria sludge enriched from the anaerobic section of the northern sewage treatment plant is inoculated into the reaction tank, and the acclimation medium sludge is fully contacted, the ratio of ammonia nitrogen and nitrite nitrogen is 1:1;

[0011] (4) Nitrogen source fluctuation acclimation: dynamically regulate the ratio of ammonia nitrogen and nitrite nitrogen, gradually fluctuate from the initial 1:1 to 1:1.5, the hydraulic retention time is 8 hours, the dissolved oxygen is controlled below 0.3 mg / L, the removal rate reaches the standard, and the activity of cytochrome c oxidase in the cells is increased by more than 30% compared with the initial stage;

[0012] (5) Continuous water acclimation: sewage is fed from the regulation tank to the reaction tank, and the sewage and the acclimation medium are mixed at a volume ratio of 1:1, and the hydraulic retention time is 8 hours;

[0013] (6) The effluent of the acclimation tank is introduced into the anaerobic tank, and the cold-tolerant Pseudomonas and Pseudomonas paludosa complex bacteria liquid is added, stirred, DO<0.2 mg / L, 8-12 ℃, pH=7.0-7.2, so that the phosphorus releasing bacteria release phosphorus, and the anaerobic ammonia oxidation bacteria preliminarily degrade ammonia nitrogen, and the residence time is 3 hours;

[0014] (7) The effluent of the anaerobic tank enters the anoxic tank, part of the mixed liquid in the aerobic tank is returned to the anoxic tank, part of the sludge in the secondary sedimentation tank is returned to the anoxic tank, and denitrification complex bacteria are added, DO=0.5-0.8 mg / L, 8-12 ℃, pH=7.2-7.5, the hydraulic retention time is 4 hours;

[0015] (8) The effluent of the anoxic tank enters the aerobic tank, intermittent aeration is adopted, DO is maintained at 2-3 mg / L, Antarctic Arthrobacter and Psychrobacter halocryophilus are added, the number of viable bacteria is 1×10 8 CFU / mL, to promote nitrification and phosphorus absorption, and the residence time is 6 hours;

[0016] (9) The sludge-water mixture treated in the aerobic tank enters the secondary sedimentation tank, and solid-liquid separation is achieved by gravity sedimentation, the clarified water on the upper layer is discharged as treated effluent, and part of the concentrated sludge at the bottom is returned to the anoxic tank for recycling, the sludge return ratio is 80%, and the other part is discharged as residual sludge.

[0017] Further, the specific process of step (1) is that the sewage is first intercepted by a grid to remove suspended matter with a diameter greater than 3 mm, and then enters the adjusting pool, the pH is controlled at 7.0-7.5, the water temperature is maintained at 6-12℃, and the hydraulic retention time is 2-4 h.

[0018] Further, in step (2), the composition of the trace element mother liquor per 1 L includes: FeSO4·7H2O 1.2 g, NiCl2·6H2O 0.8 g, CoCl2·6H2O 0.5 g, and MnCl2·4H2O 0.3 g.

[0019] Further, the specific process of step (3) is that the anaerobic ammonium oxidation bacteria sludge enriched from the anaerobic section of the northern sewage treatment plant is inoculated into the reaction tank, the MLSS concentration of the sludge is 8000 mg / L, the proportion of anaerobic ammonium oxidation bacteria is about 30%, the inoculation amount is 10% of the domestication medium, the temperature of the reaction tank is stabilized at 10±1℃, the stirring speed is 100 r / min, the initial concentrations of ammonia nitrogen and nitrite nitrogen are both 50 mg / L, and the continuous culture is carried out for 7 days. When the removal rates of both are stabilized at more than 60%, the next step is entered.

[0020] Further, the specific process of step (4) is:

[0021] Stage 1: At the beginning, the ammonia nitrogen:nitrite nitrogen ratio is 1:1.2, the concentration fluctuation range is 40-60 mg / L, the DO is maintained at less than 0.3 mg / L, the pH is maintained at 7.2±0.2, and the continuous culture is carried out for 7 days. When the average removal rate is greater than or equal to 70%, stage 2 is entered.

[0022] Stage 2: At the beginning, the ammonia nitrogen:nitrite nitrogen ratio is 1:1.3, the concentration fluctuation range is 30-70 mg / L, the DO is maintained at less than 0.3 mg / L, the pH is maintained at 7.2±0.2, and the continuous culture is carried out for 7 days. When the average removal rate is greater than or equal to 75%, stage 3 is entered.

[0023] Stage 3: At the beginning, the ammonia nitrogen:nitrite nitrogen ratio is 1:1.5, the concentration fluctuation range is 20-80 mg / L, the DO is maintained at less than 0.3 mg / L, the pH is maintained at 7.2±0.2, and the continuous culture is carried out for 7 days. When the removal rate is greater than or equal to 80% for 3 consecutive days, and the cytochrome c oxidase activity of the bacterial cells is increased by more than 30% compared with the initial stage, it is determined that the domestication in this step is completed.

[0024] Further, the specific process of step (5) is: pumping sewage from the adjusting tank to the reaction tank, SS < 50 mg / L, pH 7.0-7.5, influent flow rate 5 m³ / h, hydraulic retention time 8 hours, mixed with the domesticated culture medium at a volume ratio of 1:1, nitrogen source fluctuation in the reaction tank is the same as the above step 3, DO < 0.3 mg / L, temperature 10±1℃, 100 r / min stirring; when the ammonia nitrogen or nitrite nitrogen concentration of the effluent is > 10 mg / L, temporarily reduce the influent flow rate to 3 m³ / h, extend the retention time, and restore after stabilization;

[0025] Anaerobic ammonia oxidation bacteria account for ≥50%;

[0026] Periodically discharge sludge, and the sludge discharge amount is 5% of the sludge amount in the tank, and MLSS is stabilized at 6000-8000 mg / L.

[0027] Further, the specific process of step (6) is: the effluent of the reaction tank enters the anaerobic tank, and 0.5 mL of cold-tolerant Pseudomonas and Pseudomonas putida complex bacteria liquid is added to 1 L of sewage, and the complex bacteria liquid is continuously added to the anaerobic tank, 60 r / min stirring is uniform, DO < 0.2 mg / L, 8-12 ℃, pH = 7.0-7.2, the ratio of cold-tolerant Pseudomonas and cold-tolerant Pseudomonas putida in the Pseudomonas complex bacteria liquid is 1:1, and the viable bacterial count reaches 2×10 8 CFU / mL;

[0028] After 3 hours of retention, the ammonia nitrogen concentration is reduced to 15-25 mg / L; the total phosphorus concentration is increased by more than 50% compared with the influent, and if the standard is not met, the bacteria agent dosage or DO control needs to be checked, and if necessary, the retention time is extended to 3.5 hours;

[0029] Periodically discharge sludge, and the sludge discharge amount is 3% of the tank capacity.

[0030] Further, the specific process of step (7) is: the effluent of the anaerobic tank enters the anoxic tank, the hydraulic retention time is 4 hours, and the mixed liquid reflux pump from the aerobic tank to the anoxic tank is started, the reflux ratio is controlled at 300%, a part of the sludge in the secondary sedimentation tank is refluxed to the anoxic tank, the reflux ratio is controlled at 80%, the denitrifying complex bacteria liquid is continuously added at a ratio of 0.4 mL of bacteria agent per 1 L of sewage, 80 r / min stirring is performed to fully mix the bacteria agent, influent and refluxed mixed liquid, and sludge precipitation is avoided;

[0031] The ratio of cold-tolerant Pseudomonas veronii and Pseudomonas fluorescens in the denitrifying complex bacteria liquid is 2:1, and the viable bacterial count needs to reach 1.5×10 8 CFU / mL;

[0032] DO =0.5-0.8 mg / L, 8-12 ℃, pH = 7.2-7.5;

[0033] If the nitrate nitrogen is reduced to less than 10 mg / L, the accumulation amount of nitrite nitrogen is less than 5 mg / L, and the removal rate of nitrate nitrogen is less than 60%, it is necessary to check whether the backflow ratio meets the standard or the activity of the bacterial agent, and temporarily increase the bacterial agent dosage to 0.5 mL / L if necessary.

[0034] Periodically discharge sludge, and the sludge discharge amount is 2% of the pool capacity.

[0035] Further, the specific process of the step (8) is that the effluent of the anoxic tank enters the aerobic tank, the hydraulic retention time is 6 hours, the aeration is stopped for 10 minutes after 30 minutes of aeration, and the cycle is carried out, the DO is 2-3 mg / L during aeration, and the DO naturally decreases to 1-1.5 mg / L during the aeration stop;

[0036] The nitration composite bacterial agent is continuously added to the aerobic tank at a ratio of 0.3 mL of the bacterial agent per 1 L of sewage, the bacterial agent is uniformly mixed with the sewage at 60 r / min, the temperature is 8-12℃, the pH is controlled to be 7.5-8.0, and the MLSS is 4000-6000 mg / L;

[0037] The nitration composite bacterial agent includes Antarctic Arthrobacter and Psychrobacter cryohalolitus, and the ratio is 1:1, and the viable bacterial count is 1×10 8 CFU / mL.

[0038] The present application has the advantages that the anaerobic ammonia oxidation bacteria subjected to directional domestication are combined with the cold-tolerant composite bacteria, the low-temperature adaptability and the nitrogen source fluctuation tolerance are considered, the fluctuation characteristics of the actual sewage are simulated in the domestication stage, the strains are "pre-adapted", the carbon source addition is reduced through the cooperation of the endogenous denitrification tank and the anaerobic tank, and the operation cost is reduced. DETAILED DESCRIPTION

[0039] The present application will be described in detail below in combination with schemes and specific embodiments, and the illustrative embodiments and descriptions of the present application are used to explain the present application, but not as a limitation of the present application.

[0040] The present embodiment provides a high-efficiency denitrification sewage treatment method, and the steps include:

[0041] (1) Pretreatment and water quality homogenization: the sewage is first intercepted by a grid to remove suspended matters with a diameter greater than 3 mm, and then enters a regulating tank, the pH is controlled to be 7.0-7.5, the water temperature is maintained to be 6-12℃, and the hydraulic retention time is 2-4 h, so as to provide a stable water quality basis for nitrogen source domestication;

[0042] (2) Prepare the acclimation medium, and pump the acclimation medium into the reaction tank: the acclimation medium includes NH4Cl 0.1-0.2 g, NaNO2 0.1-0.3 g, KH2PO4 0.05 g, MgSO4·7H2O 0.2 g, CaCl2 0.1 g, 10 mL trace element mother liquor, and 10% HCl solution or NaOH solution is used to adjust the pH to 7.2±0.1 for 1 L of volume;

[0043] The trace element mother liquor includes FeSO4·7H2O 1.2 g, NiCl2·6H2O 0.8 g, CoCl2·6H2O 0.5 g, MnCl2·4H2O 0.3 g for 1 L of volume;

[0044] (3) Anaerobic ammonia oxidation bacteria inoculation and initial culture: anaerobic ammonia oxidation bacteria sludge enriched from the anaerobic section of the northern sewage treatment plant is inoculated into the reaction tank, the MLSS concentration of the sludge is 8000 mg / L, the proportion of anaerobic ammonia oxidation bacteria is about 30%, the inoculation amount is 10% of the acclimation medium, the temperature of the reaction tank is stabilized at 10±1 ℃, 100 r / min stirring is performed, the sludge is fully contacted with the acclimation medium, the initial concentrations of ammonia nitrogen and nitrite nitrogen are both 50 mg / L, continuous culture is performed for 7 days, the effluent ammonia nitrogen and nitrite nitrogen concentrations are detected every morning, when the removal rates of the two are both stabilized at more than 60%, the next step is entered;

[0045] (4) Nitrogen source fluctuation acclimation:

[0046] Stage 1: initially, ammonia nitrogen:nitrite nitrogen = 1:1.2, the concentration fluctuation range is 40-60 mg / L, DO is maintained to be less than 0.3 mg / L, pH is maintained to be 7.2±0.2, continuous culture is performed for 7 days, when the average removal rate is greater than or equal to 70%, stage 2 is entered;

[0047] Stage 2: initially, ammonia nitrogen:nitrite nitrogen = 1:1.3, the concentration fluctuation range is 30-70 mg / L, DO is maintained to be less than 0.3 mg / L, pH is maintained to be 7.2±0.2, continuous culture is performed for 7 days, when the average removal rate is greater than or equal to 75%, stage 3 is entered;

[0048] Stage 3: initially, ammonia nitrogen:nitrite nitrogen = 1:1.5, the concentration fluctuation range is 20-80 mg / L, DO is maintained to be less than 0.3 mg / L, pH is maintained to be 7.2±0.2, continuous culture is performed for 7 days, when the removal rate is greater than or equal to 80% for 3 consecutive days, and the cytochrome c oxidase activity of the bacteria is increased by more than 30% compared with that in the initial stage, it is determined that the acclimation in this step is completed;

[0049] (5) Continuous water feeding acclimation and stable parameters:

[0050] Pump the sewage from the conditioning tank to the reaction tank, SS < 50 mg / L, pH 7.0-7.5, influent flow rate 5 m³ / h, hydraulic retention time 8 hours, mixed with acclimated culture medium at a volume ratio of 1:1, nitrogen source fluctuation in the reaction tank as in step 3 of the previous stage, DO < 0.3 mg / L, temperature 10±1℃, 100 r / min stirring; record the effluent ammonia nitrogen and nitrite nitrogen concentrations every 2 hours, when the effluent ammonia nitrogen or nitrite nitrogen concentration > 10 mg / L, temporarily reduce the influent flow rate to 3 m³ / h, extend the retention time, and restore after stabilization;

[0051] Sample and analyze the proportion of anaerobic ammonia oxidation bacteria in the sludge every week, the proportion should be ≥ 50%, such as detected by fluorescence in situ hybridization (FISH) technology;

[0052] Discharge residual sludge every 3 days, the sludge discharge amount is 5% of the sludge amount in the tank, to ensure that the MLSS is stable at 6000-8000 mg / L;

[0053] After acclimation, the removal rate of ammonia nitrogen and nitrite nitrogen of the anaerobic ammonia oxidation bacteria can reach more than 85% under the conditions of 8-12℃ and nitrogen source fluctuation (20-80 mg / L), laying a foundation for the subsequent collaborative denitrification process.

[0054] (6) The effluent from the reaction tank enters the anaerobic tank, and 0.5 mL of cold-tolerant Pseudomonas and Pseudomonas putida complex bacterial solution is added to 1 L of sewage, and the complex bacterial solution is continuously added to the anaerobic tank, stirred at 60 r / min for 10 minutes to ensure that the bacterial solution and sewage are fully mixed, DO < 0.2 mg / L, 8-12℃, pH = 7.0-7.2, 10% NaOH solution or 10% HCl solution is used to adjust the pH; the ratio of cold-tolerant Pseudomonas and cold-tolerant Pseudomonas putida in the Pseudomonas complex bacterial solution is 1:1, and the viable bacterial count reaches 2×10 8 CFU / mL;

[0055] After 3 hours of retention, the ammonia nitrogen concentration is reduced to 15-25 mg / L (primary degradation rate 30%-40%); the total phosphorus concentration is increased by more than 50% compared with the influent (a sign of phosphorus release by phosphorus accumulating organisms). If not up to standard, check the bacterial agent dosage or DO control, and if necessary, extend the retention time to 3.5 hours.

[0056] Discharge sludge every 2 days, the sludge discharge amount is 3% of the tank volume, to avoid sludge accumulation affecting the reaction;

[0057] Through the above operations, the anaerobic tank can achieve sufficient phosphorus release by phosphorus accumulating organisms, preparing for the subsequent aerobic phosphorus uptake, and allowing the cold-tolerant complex bacteria and anaerobic ammonia oxidation bacteria to cooperate to preliminarily degrade ammonia nitrogen, providing suitable substrate for the denitrification reaction in the anoxic tank.

[0058] (7) The effluent of the anaerobic tank enters the anoxic tank, and the hydraulic retention time is 4 hours. At the same time, the mixed liquid reflux pump from the aerobic tank to the anoxic tank is started, and the reflux ratio is controlled at 300%. A part of the sludge in the secondary sedimentation tank is refluxed to the anoxic tank, and the reflux ratio is controlled at 80%. The mixed liquid and sludge containing nitrate nitrogen produced by the aerobic tank provide substrates for denitrification. The proportion of 0.4 mL of bacteria agent to 1 L of sewage is continuously added to the denitrification composite bacteria liquid, and stirring is carried out at 80 r / min to make the bacteria agent, influent and refluxed mixed liquid fully mixed to avoid sludge sedimentation;

[0059] The proportion of Pseudomonas veronii and Pseudomonas fluorescens in the composite bacteria liquid is 2:1, and the viable bacterial count needs to reach 1.5×10 8 CFU / mL.

[0060] DO =0.5-0.8 mg / L, 8-12 ℃, pH = 7.2-7.5, if the pH deviates, adjust it by adding 10% HCl or NaOH solution.

[0061] Every 2 hours, 500 mL of water sample is taken from the front, middle and rear ends of the tank body, and the concentration of nitrate nitrogen (ultraviolet spectrophotometry) and the concentration of nitrite nitrogen (N-(1-naphthyl)-ethylenediamine spectrophotometry) are detected.

[0062] Index requirements: the effluent nitrate nitrogen needs to be reduced to below 10 mg / L, and the accumulation of nitrite nitrogen is less than 5 mg / L (to avoid inhibiting the subsequent reaction). If the nitrate nitrogen removal rate is less than 60%, check whether the reflux ratio meets the standard or the activity of the bacteria agent, and temporarily increase the bacteria agent dosage to 0.5 mL / L if necessary.

[0063] Sludge is discharged once a week, and the sludge discharge amount is 2% of the tank capacity to prevent the sludge age from being too long and causing the activity of denitrifying bacteria to decrease.

[0064] The denitrifying bacteria and anaerobic ammonia oxidation bacteria work together to convert nitrate nitrogen into nitrogen gas. The anoxic tank can stably remove more than 70% of the nitrate nitrogen, which reduces the treatment load of the subsequent aerobic tank and improves the overall nitrogen removal efficiency of the system.

[0065] (8) The effluent of the anoxic tank enters the aerobic tank, and the hydraulic retention time is 6 hours. Aeration is carried out for 30 minutes and then stopped for 10 minutes, and the cycle is repeated. When aeration is carried out, DO = 2-3 mg / L, which is the active range of nitrifying bacteria. When aeration is stopped, DO naturally decreases to 1-1.5 mg / L, which ensures that the nitrification reaction is sufficient and avoids wasting energy.

[0066] The nitrification composite microbial agent is continuously added to the aerobic tank at a ratio of 0.3 mL of the microbial agent per 1 L of sewage, the microbial agent is uniformly mixed with the sewage at 60 r / min, the pH is controlled at 7.5-8.0 at 8-12℃, the pH is adjusted by 10% sodium carbonate solution or 10% sulfuric acid solution, the MLSS is 4000-6000 mg / L, if the MLSS is lower than 4000 mg / L, the amount of residual sludge discharge is reduced, and if the MLSS is higher than 6000 mg / L, the sludge is discharged to reach the concentration standard.

[0067] The nitrification composite microbial agent comprises Antarctic Arthrobacter and Psychrobacter cryohalolitus, the ratio is 1:1, and the viable bacterial count is 1×10 8 CFU / mL.

[0068] The ammonia nitrogen in the influent is about 15-25 mg / L, after 6 hours of reaction, the ammonia nitrogen removal rate needs to be ≥90%, that is, the effluent ammonia nitrogen is ≤2.5 mg / L, the amount of nitrate nitrogen generated is roughly matched with the amount of ammonia nitrogen removed, the phosphorus-absorbing polyphosphorus bacteria reduce the total phosphorus from 4.5-7.5 mg / L in the effluent of the anaerobic tank to below 1 mg / L, and if the standard is not met, the aeration time or the activity of the microbial agent is checked, and if necessary, the aeration cycle is prolonged.

[0069] The aerobic tank can efficiently complete the nitrification reaction and the phosphorus absorption, provides sufficient nitrate nitrogen substrate for the subsequent endogenous denitrification tank, and reduces the total phosphorus concentration in the sewage, thereby laying a foundation for the final standard discharge.

[0070] (9) The sludge-water mixture treated by the aerobic tank enters the secondary sedimentation tank, the solid-liquid separation is realized through gravity sedimentation, the upper clear water is discharged as the treated effluent, a part of the sludge concentrated at the bottom is recycled to the anoxic tank for recycling, the sludge recycling ratio is 80%, and the other part is discharged from the system as residual sludge.

[0071] The technical solutions provided by the embodiments of the present application are described in detail above, specific examples are applied in this paper to describe the principles and implementation modes of the embodiments of the present application, the above description of the embodiments is only applicable to help understand the principles of the embodiments of the present application; meanwhile, for those skilled in the art, according to the embodiments of the present application, the specific implementation modes and application ranges will be changed, and according to the above, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A highly efficient wastewater treatment method for nitrogen removal, characterized in that the steps include... include: (1) Pretreatment and water quality equalization: After physical removal of large particulate suspended solids, the wastewater enters the equalization tank to stabilize the water quality, so that the wastewater pH = 7.0-7.5 and the water temperature is maintained at 6-12 ℃; (2) Prepare the acclimatization culture medium and pump it into the reaction tank: Based on 1 L volume, the acclimatization culture medium consists of 0.1-0.2 g of NH4Cl, 0.1-0.3 g of NaNO2, 0.05 g of KH2PO4, 0.2 g of MgSO4・7H2O, 0.1 g of CaCl2, 10 mL of trace element stock solution, and adjust the pH to 7.2±0.1 with 10% HCl solution or NaOH solution; (3) Inoculation and initial culture of anaerobic ammonia oxidizing bacteria: sludge enriched from the anaerobic section of the northern sewage treatment plant is inoculated into the reaction tank, and the sludge is fully contacted with the acclimatization culture medium. The ratio of ammonia nitrogen to nitrite nitrogen is 1:

1. (4) Nitrogen source fluctuation acclimatization: The ratio of ammonia nitrogen and nitrite nitrogen was dynamically adjusted from the initial 1:1 to 1:1.5, the hydraulic retention time was 8 hours, the dissolved oxygen was controlled below 0.3 mg / L, the removal rate met the standard, and the activity of cytochrome c oxidase in the bacteria increased by more than 30% compared with the initial stage. (5) Continuous influent acclimatization: Wastewater is fed from the equalization tank into the reaction tank. The volume ratio of wastewater to acclimatization culture medium is 1:1, and the hydraulic retention time is 8 hours. (6) Introduce the effluent from the acclimatization tank into the anaerobic tank, add a compound bacterial solution of cold-resistant Pseudomonas aeruginosa and Pseudomonas sphaeroides, stir, DO < 0.2 mg / L, 8-12 ℃, pH = 7.0-7.2, so that polyphosphate-accumulating bacteria release phosphorus, while anaerobic ammonia-oxidizing bacteria initially degrade ammonia nitrogen, with a residence time of 3 hours; (7) The effluent from the anaerobic tank enters the anoxic tank, a portion of the mixed liquor from the aerobic tank is returned to the anoxic tank, and a portion of the sludge from the secondary sedimentation tank is returned to the anoxic tank. Denitrifying compound bacteria are added, DO = 0.5-0.8 mg / L, 8-12 ℃, pH = 7.2-7.5, and hydraulic retention time is 4 hours. (8) The effluent from the anoxic tank enters the aerobic tank, where intermittent aeration is used, DO is maintained at 2-3 mg / L, and Antarctic Arthrobacter and Psychrophilic Bacillus halophilus are added, with a viable count of 1×10⁻⁶. 8 CFU / mL, promotes nitration and phosphorus absorption, residence time 6 hours; (9) The mud-water mixture after aerobic tank treatment enters the secondary sedimentation tank, where solid and liquid are separated by gravity sedimentation. The clarified water in the upper layer is discharged as treated effluent, and part of the concentrated sludge at the bottom is returned to the anoxic tank for recycling. The sludge return ratio is 80%, and the other part is discharged from the system as excess sludge.

2. The wastewater treatment method for high-efficiency nitrogen removal according to claim 1, characterized in that, The specific process of step (1) is as follows: the sewage first passes through a screen to intercept suspended solids with a diameter > 3 mm, and then enters the equalization tank, where the pH is controlled at 7.0~7.5, the water temperature is maintained at 6~12 ℃, and the hydraulic retention time is 2~4 h.

3. The wastewater treatment method for high-efficiency nitrogen removal according to claim 2, characterized in that, In step (2), the components of the trace element mother liquor, based on a volume of 1L, include: FeSO4・7H2O 1.2 g, NiCl2・6H2O 0.8 g, CoCl2・6H2O 0.5 g, and MnCl2・4H2O 0.3 g.

4. The wastewater treatment method for high-efficiency nitrogen removal according to claim 2, characterized in that, The specific process of step (3) is as follows: anaerobic ammonia-oxidizing bacteria sludge enriched from the anaerobic section of the northern sewage treatment plant is inoculated into the reaction tank. The sludge has an MLSS concentration of 8000 mg / L, and the proportion of anaerobic ammonia-oxidizing bacteria is about 30%. The inoculation amount is 10% of the acclimatization medium. The temperature of the reaction tank is kept stable at 10±1 ℃, and the mixture is stirred at 100 r / min. The initial concentrations of ammonia nitrogen and nitrite nitrogen are both 50 mg / L. The mixture is continuously cultured for 7 days. When the removal rates of both are stable at more than 60%, the next step of treatment is carried out.

5. The wastewater treatment method for high-efficiency nitrogen removal according to claim 3, characterized in that, The specific process of step (4) is as follows: Phase 1: Initially, the ratio of ammonia nitrogen to nitrite nitrogen is 1:1.2, with a concentration fluctuation range of 40-60 mg / L. Maintain DO < 0.3 mg / L and pH = 7.2 ± 0.

2. Culture continuously for 7 days. When the average removal rate is ≥ 70%, proceed to Phase 2. Phase 2: Initially, the ratio of ammonia nitrogen to nitrite nitrogen is 1:1.3, with a concentration fluctuation range of 30-70 mg / L. Maintain DO < 0.3 mg / L and pH = 7.2 ± 0.

2. Culture continuously for 7 days. When the average removal rate is ≥ 75%, proceed to Phase 3. Phase 3: Initially, the ratio of ammonia nitrogen to nitrite nitrogen is 1:1.5, with a concentration fluctuation range of 20-80 mg / L. Maintain DO < 0.3 mg / L and pH = 7.2 ± 0.

2. Culture continuously for 7 days. When the removal rate is ≥ 80% for 3 consecutive days and the cytochrome c oxidase activity in the bacteria increases by more than 30% compared to the initial phase, the acclimatization of this step is considered complete.

6. The wastewater treatment method for high-efficiency nitrogen removal according to claim 1, characterized in that, The specific process of step (5) is as follows: Sewage is pumped from the equalization tank to the reaction tank, with SS < 50 mg / L, pH 7.0-7.5, influent flow rate 5 m³ / h, hydraulic retention time 8 hours, and mixed with acclimatization culture medium at a volume ratio of 1:

1. The nitrogen source fluctuation in the reaction tank is the same as in the previous step 3, DO < 0.3 mg / L, temperature 10±1℃, and stirring at 100 r / min. When the concentration of ammonia nitrogen or nitrite nitrogen in the effluent is > 10 mg / L, the influent flow rate is temporarily reduced to 3 m³ / h, the retention time is extended, and it is restored after stabilization. Anaerobic ammonia-oxidizing bacteria account for ≥50%; Regularly remove sludge, with the amount being 5% of the total sludge volume in the tank, and maintain MLSS levels stable at 6000-8000 mg / L.

7. The wastewater treatment method for high-efficiency nitrogen removal according to claim 1, characterized in that, The specific process of step (6) is as follows: the effluent from the reaction tank enters the anaerobic tank, and the compound bacterial solution is continuously added to the anaerobic tank at a ratio of 0.5 mL of cold-resistant Pseudomonas aeruginosa and Pseudomonas sphaeroides per 1 L of sewage. The mixture is stirred evenly at 60 r / min, with DO < 0.2 mg / L, 8-12 ℃, and pH = 7.0-7.

2. The ratio of cold-resistant Pseudomonas aeruginosa to cold-resistant Pseudomonas sphaeroides in the compound bacterial solution is 1:1, and the viable count reaches 2 × 10⁻⁶. 8 CFU / mL; After a 3-hour retention period, the ammonia nitrogen concentration drops to 15-25 mg / L; the total phosphorus concentration increases by more than 50% compared to the influent. If the standard is not met, the dosage of bacterial agent or DO control needs to be checked, and the retention time should be extended to 3.5 hours if necessary. Regularly remove sludge, with the amount of sludge removed being 3% of the pond's volume.

8. The wastewater treatment method for high-efficiency nitrogen removal according to claim 6, characterized in that, The specific process of step (7) is as follows: the effluent from the anaerobic tank enters the anoxic tank, with a hydraulic retention time of 4 hours. At the same time, the mixed liquor return pump from the aerobic tank to the anoxic tank is started, and the return ratio is controlled at 300%. A portion of the sludge in the secondary sedimentation tank is returned to the anoxic tank, and the return ratio is controlled at 80%. Denitrification compound bacterial liquid is continuously added at a ratio of 0.4 mL of bacterial agent per 1 L of sewage. The mixture is stirred at 80 r / min to ensure that the bacterial agent, influent, and return mixed liquor are fully mixed to avoid sludge sedimentation. The ratio of cold-resistant Pseudomonas veronatum to Pseudomonas fluorescens in the denitrifying compound bacterial solution is 2:1, and the viable count needs to reach 1.5 × 10⁻⁶. 8 CFU / mL; DO =0.5-0.8 mg / L, 8-12 ℃, pH = 7.2-7.5; If nitrate nitrogen drops below 10 mg / L and nitrite nitrogen accumulation is <5 mg / L, and if the nitrate nitrogen removal rate is less than 60%, the reflux ratio or bacterial activity should be checked. If necessary, the bacterial agent dosage should be temporarily increased to 0.5 mL / L. Regularly remove sludge, with the amount of sludge removed being 2% of the pond's volume.

9. The wastewater treatment method for efficient nitrogen removal according to claim 7, characterized in that, The specific process of step (8) is as follows: the effluent from the anoxic tank enters the aerobic tank, the hydraulic retention time is 6 hours, aeration is carried out for 30 minutes and then stopped for 10 minutes, and the cycle is repeated. During aeration, DO = 2-3 mg / L, and when aeration stops, DO naturally drops to 1-1.5 mg / L. Continuously add nitrifying compound bacteria to the aerobic tank at a ratio of 0.3 mL of bacteria per 1 L of wastewater, mix the bacteria with the wastewater at 60 r / min, maintain the temperature at 8-12℃, control the pH at 7.5-8.0, and keep the MLSS at 4000-6000 mg / L. The nitrifying compound microbial agent includes *Arthrobacter antarcticus* and *Psychrophilus halophilus* in a 1:1 ratio, with a viable count of 1×10⁻⁶. 8 CFU / mL.