A method for treating industrial wastewater rich in high concentrations of nitric acid

Abstract

The application discloses a kind of high-concentration nitric acid-rich industrial wastewater treatment method, belong to the technical field of range, in the application, by the synergistic effect of catalytic oxidation and biological denitrification, the processing efficiency of high-concentration nitric acid and ammonia nitrogen wastewater is significantly improved.Catalytic oxidation stage adopts Fe-Cu bimetallic catalyst directional regulation and control nitrogen form, part of ammonia nitrogen is oxidized into nitrite while nitrate is reduced, nitrosation accumulation is formed, and the subsequent biological treatment load is greatly reduced.Biological denitrification stage is coupled by short-path denitrification and anaerobic ammonia oxidation path, directly with ammonia as electron donor and nitrite derivative reaction to generate nitrogen, not only reduce more than 60% carbon source demand, but also reduce 40% sludge production, compared with traditional process, the comprehensive operation cost is saved by more than 50%, and no secondary pollutant is generated throughout.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment technology, specifically a method for treating industrial wastewater rich in high concentrations of nitric acid. Background Technology

[0002] Acid etching processes in the glass processing industry can generate high concentrations of nitric acid and ammonia nitrogen during the etching process. The ammonia nitrogen concentration often reaches over 3000 mg / L, which poses a great challenge to subsequent industrial wastewater treatment.

[0003] However, traditional treatment methods for industrial wastewater containing both high concentrations of ammonia nitrogen and nitric acid have the following problems: chemical methods are costly and produce complex byproducts; biological methods are inhibited by high concentrations of nitric acid, require large carbon sources for denitrification, and are difficult to achieve emission standards; physical methods are prone to clogging and cannot completely degrade pollutants. Summary of the Invention

[0004] The purpose of this invention is to provide a method for treating industrial wastewater rich in high concentrations of nitric acid in order to solve the problems mentioned above.

[0005] The technical solution adopted in this invention is as follows: A method for treating industrial wastewater rich in high concentrations of nitric acid, comprising the following steps:

[0006] S1: Adjust the pH of the industrial wastewater to the range of 3-5 to ensure the efficient execution of subsequent catalytic oxidation reactions.

[0007] S2: A supported Fe-Cu bimetallic catalyst was added to the wastewater at a mass ratio of 3:1 for iron to copper, with activated carbon as the support, to enhance catalytic activity and stability.

[0008] S3: Add hydrogen peroxide to the wastewater at a dosage of 0.1 mol / L to provide a source of hydroxyl radicals required for the oxidation reaction.

[0009] S4: Under the temperature conditions of 45-55℃, the reaction is continued for 1.5-2.5 hours, so that the molar ratio of ammonia nitrogen to nitrate is close to 1:1.3. At the same time, some ammonia nitrogen is oxidized to nitrite and nitrate is reduced to nitrite, forming nitrite accumulation.

[0010] S5: Introduce the wastewater after catalytic oxidation treatment into the anaerobic bioreactor, add microbial activated sludge rich in short-range denitrifying bacteria, and start the biological denitrification process.

[0011] S6: Control the dissolved oxygen concentration in the bioreactor to below 0.2 mg / L, maintain the temperature in the range of 30-38℃, and optimize the metabolic activity of microorganisms.

[0012] S7: Adjust the hydraulic retention time to 10-15 hours and control the carbon-to-nitrogen ratio at 0.5 to promote the reduction of nitrite to nitric oxide by short-range denitrifying bacteria.

[0013] S8: Anaerobic ammonia-oxidizing bacteria use ammonia as an electron donor to react with nitric oxide to generate nitrogen gas, achieving simultaneous denitrification, and finally reducing the total nitrogen concentration to below 50 mg / L.

[0014] S9: Recover the Fe-Cu bimetallic catalyst and recycle it at least 20 times to verify that the ammonia nitrogen concentration in the effluent is less than 15 mg / L and meets the emission standards of the chemical industry, thus completing the wastewater treatment.

[0015] In a preferred embodiment, in step S1, the wastewater to be treated is introduced into an acid-resistant reaction tank, and a 10% sulfuric acid solution or a 5% sodium hydroxide solution is precisely added using a metering pump to strictly control the pH value within the range of 3.0-5.0. The adjustment rate is 0.5-1.0 L / min, ensuring that pH fluctuations do not exceed ±0.2. The acidic environment can activate the redox activity of the Fe-Cu catalyst while inhibiting the formation of side reactions.

[0016] In a preferred embodiment, in step S2, a catalyst is prepared at an iron to copper mass ratio of 3:1, and 20-30g of supported catalyst is added per liter of wastewater. The particle size of the supported activated carbon is 1-2mm, and the specific surface area is 800-1000m². 2 / g, porosity ≥85% Fe in the catalyst 3 + with Cu 2 The loadings of ⁺ and ⁴⁵wt% were 12-15wt% and 4-5wt%, respectively, and the metals were prepared by impregnation-calcination method, with the calcination temperature controlled at 450-500℃ to maintain the activity of the metals.

[0017] In a preferred embodiment, in step S3, hydrogen peroxide (H2O2) is used as the oxidant, added at a standard concentration of 0.1 mol / L, equivalent to adding 3.4 kg of 30% hydrogen peroxide stock solution per ton of wastewater. The addition rate is 0.2 L / min, and a static mixer is used to ensure sufficient contact between the reagent and the wastewater, avoiding ineffective decomposition due to excessively high local concentrations.

[0018] In a preferred embodiment, in step S4, the temperature is maintained at 45-55℃ (temperature control accuracy ±1℃) in a mechanically stirred reactor, the stirring speed is 200-300 rpm, and the reaction time is 1.5-2.5 hours. After the reaction, the ammonia nitrogen concentration decreases from the initial 3000 mg / L to below 800 mg / L, the nitrate conversion rate is ≥85%, the nitrite accumulation reaches 2000-2200 mg / L, and the ammonia nitrogen to nitrate molar ratio is stabilized at 1:1.25-1:1.35.

[0019] In a preferred embodiment, in step S5, short-range denitrifying bacteria are added to the sequencing batch reactor (SBR), maintaining a sludge concentration of 5000-8000 mg / L and an inoculum ratio of 10%-15%. The reactor's effective volume accounts for 80% of the total volume, the upward flow velocity is 0.5-1.0 m / h, and the initial load is set at 0.3 kg N / m³. 3 / d, increasing by 20% every 48 hours until the design load of 0.8 kg N / m is reached. 3 / d.

[0020] In a preferred embodiment, in step S6, a nitrogen purging system is used to stabilize the dissolved oxygen concentration at 0.1-0.2 mg / L and maintain the oxidation-reduction potential (ORP) below -200 mV. The temperature is controlled at 30-38°C using a coil heat exchanger, with 35-38°C being the optimal activity range for anaerobic ammonia-oxidizing bacteria. A temperature sensor collects data every 15 minutes, with an adjustment accuracy of ±0.5°C.

[0021] In a preferred embodiment, in step S7, the hydraulic retention time (HRT) is set to 12 ± 2 hours, and sodium acetate is used as an external carbon source, added at a ratio of COD / N = 0.5, with 200-300 mg of sodium acetate (purity ≥ 99%) added per liter of wastewater. The COD / BOD5 ratio is controlled between 0.3 and 0.5 to ensure that the effective utilization rate of the carbon source is ≥ 90%.

[0022] In a preferred embodiment, in step S8, under anaerobic conditions, short-range denitrifying bacteria convert 80%–85% of nitrite to NO, and anaerobic ammonia-oxidizing bacteria use NH3 as an electron donor to remove nitrogen at a stoichiometric ratio of NH3:NO = 1:1.3. The total nitrogen removal load reaches 0.5–0.8 kg N / m³. 3 / d, nitrite removal rate ≥95%, final effluent total nitrogen concentration stable at 40-50mg / L, ammonia nitrogen concentration ≤15mg / L.

[0023] In a preferred embodiment, in step S9, a high-gradient magnetic separation device is used to recover the Fe-Cu bimetallic catalyst, with a magnetic field strength ranging from 1.2 to 1.5 Tesla, and a catalyst recovery rate of not less than 98%. The recovered catalyst is activated by soaking in a 10% hydrochloric acid solution for 30 minutes, followed by drying at 50 degrees Celsius, and can be recycled more than 20 times. The treated effluent needs to be tested for multiple indicators, including an ammonia nitrogen detection limit of 0.1 mg / L, a total nitrogen detection limit of 1 mg / L, a pH value controlled between 6.5 and 7.5, and a suspended solids content not exceeding 30 mg / L, to ensure that all indicators meet the requirements of DB41 / 1135-2016 Chemical Industry Water Pollutant Indirect Discharge Standard, ultimately achieving safe wastewater discharge and efficient resource reuse.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. In this invention, the treatment efficiency of high-concentration nitric acid and ammonia nitrogen wastewater is significantly improved through the synergistic effect of catalytic oxidation and biological denitrification. In the catalytic oxidation stage, an Fe-Cu bimetallic catalyst is used to directionally regulate nitrogen speciation, oxidizing some ammonia nitrogen to nitrite while simultaneously reducing nitrate, leading to nitrite accumulation and significantly reducing the load on subsequent biological treatment. In the biological denitrification stage, a coupled pathway of short-cut denitrification and anaerobic ammonia oxidation is used, directly reacting ammonia as an electron donor with nitrite derivatives to generate nitrogen gas. This not only reduces carbon source requirements by more than 60% but also reduces sludge production by 40%, resulting in overall operating costs that are more than 50% lower than traditional processes, and no secondary pollutants are generated throughout the entire process.

[0026] 2. In this invention, the catalyst is efficiently recovered and recycled more than 20 times through magnetic separation technology, reducing metal resource consumption and solid waste discharge. The ammonia nitrogen concentration in the treated effluent is consistently below 15 mg / L, and the total nitrogen concentration is below 50 mg / L, fully meeting the indirect emission standards of the chemical industry. The entire process breaks through the bottlenecks of traditional technologies, achieving efficient degradation and resource recycling of high-concentration nitric acid and ammonia nitrogen wastewater, providing a reliable solution for the green treatment of industrial wastewater. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating the process principle of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] A method for treating industrial wastewater rich in high concentrations of nitric acid includes the following steps:

[0030] S1: Adjust the pH of the industrial wastewater to the range of 3-5 to ensure the efficient execution of subsequent catalytic oxidation reactions.

[0031] S2: A supported Fe-Cu bimetallic catalyst was added to the wastewater at a mass ratio of 3:1 for iron to copper, with activated carbon as the support, to enhance catalytic activity and stability.

[0032] S3: Add hydrogen peroxide to the wastewater at a dosage of 0.1 mol / L to provide a source of hydroxyl radicals required for the oxidation reaction.

[0033] S4: Under the temperature conditions of 45-55℃, the reaction is continued for 1.5-2.5 hours, so that the molar ratio of ammonia nitrogen to nitrate is close to 1:1.3. At the same time, some ammonia nitrogen is oxidized to nitrite and nitrate is reduced to nitrite, forming nitrite accumulation.

[0034] S5: Introduce the wastewater after catalytic oxidation treatment into the anaerobic bioreactor, add microbial activated sludge rich in short-range denitrifying bacteria, and start the biological denitrification process.

[0035] S6: Control the dissolved oxygen concentration in the bioreactor to below 0.2 mg / L, maintain the temperature in the range of 30-38℃, and optimize the metabolic activity of microorganisms.

[0036] S7: Adjust the hydraulic retention time to 10-15 hours and control the carbon-to-nitrogen ratio at 0.5 to promote the reduction of nitrite to nitric oxide by short-range denitrifying bacteria.

[0037] S8: Anaerobic ammonia-oxidizing bacteria use ammonia as an electron donor to react with nitric oxide to generate nitrogen gas, achieving simultaneous denitrification, and finally reducing the total nitrogen concentration to below 50 mg / L.

[0038] S9: Recover the Fe-Cu bimetallic catalyst and recycle it at least 20 times to verify that the ammonia nitrogen concentration in the effluent is less than 15 mg / L and meets the emission standards of the chemical industry, thus completing the wastewater treatment.

[0039] In step S1, the wastewater to be treated is introduced into an acid-resistant reaction tank. A 10% sulfuric acid solution or a 5% sodium hydroxide solution is precisely added using a metering pump to strictly control the pH value within the range of 3.0-5.0. The adjustment rate is 0.5-1.0 L / min, ensuring that pH fluctuations do not exceed ±0.2. The acidic environment can activate the redox activity of the Fe-Cu catalyst while inhibiting the formation of side reactions.

[0040] In step S2, a catalyst is prepared with an iron to copper mass ratio of 3:1, and 20-30g of supported catalyst is added per liter of wastewater. The particle size of the supported activated carbon is 1-2mm, and the specific surface area is 800-1000m². 2 / g, porosity ≥85% Fe in the catalyst 3 + with Cu 2 The loadings of ⁺ and ⁴⁵wt% were 12-15wt% and 4-5wt%, respectively, and the metals were prepared by impregnation-calcination method, with the calcination temperature controlled at 450-500℃ to maintain the activity of the metals.

[0041] In step S3, hydrogen peroxide (H2O2) is used as the oxidant, added at a standard concentration of 0.1 mol / L, which is equivalent to adding 3.4 kg of 30% hydrogen peroxide stock solution per ton of wastewater. The addition rate is 0.2 L / min, and a static mixer is used to ensure sufficient contact between the reagent and the wastewater, avoiding excessively high local concentrations that could lead to ineffective decomposition.

[0042] In step S4, the temperature is maintained at 45-55℃ (temperature control accuracy ±1℃) in a mechanically stirred reactor, the stirring speed is 200-300 rpm, and the reaction time is 1.5-2.5 hours. After the reaction, the ammonia nitrogen concentration decreases from the initial 3000 mg / L to below 800 mg / L, the nitrate conversion rate is ≥85%, the nitrite accumulation reaches 2000-2200 mg / L, and the ammonia nitrogen to nitrate molar ratio stabilizes at 1:1.25-1:1.35.

[0043] In step S5, short-cut denitrifying bacteria are added to the sequencing batch reactor (SBR), maintaining a sludge concentration of 5000-8000 mg / L and an inoculum ratio of 10%-15%. The reactor's effective volume accounts for 80% of the total volume, the upward flow velocity is 0.5-1.0 m / h, and the initial load is set at 0.3 kg N / m³. 3 / d, increasing by 20% every 48 hours until the design load of 0.8 kg N / m is reached. 3 / d.

[0044] In step S6, a nitrogen purging system is used to stabilize the dissolved oxygen concentration at 0.1-0.2 mg / L and maintain the oxidation-reduction potential (ORP) below -200 mV. The temperature is controlled at 30-38℃ using a coil heat exchanger, with 35-38℃ being the optimal activity range for anaerobic ammonia-oxidizing bacteria. A temperature sensor collects data every 15 minutes, with an adjustment accuracy of ±0.5℃.

[0045] In step S7, the hydraulic retention time (HRT) is set to 12 ± 2 hours. Sodium acetate is used as an external carbon source and is added at a ratio of COD / N = 0.5, with 200-300 mg of sodium acetate (purity ≥ 99%) added per liter of wastewater. The COD / BOD5 ratio is controlled between 0.3 and 0.5 to ensure that the effective utilization rate of the carbon source is ≥ 90%.

[0046] In step S8, under anaerobic conditions, short-cut denitrifying bacteria convert 80%–85% of nitrite to NO, while anaerobic ammonia-oxidizing bacteria use NH3 as an electron donor to remove nitrogen at a stoichiometric ratio of NH3:NO = 1:1.3. The total nitrogen removal load reaches 0.5–0.8 kg N / m³. 3 / d, nitrite removal rate ≥95%, final effluent total nitrogen concentration stable at 40-50mg / L, ammonia nitrogen concentration ≤15mg / L.

[0047] In step S9, a high-gradient magnetic separation device is used to recover the Fe-Cu bimetallic catalyst, with a magnetic field strength ranging from 1.2 to 1.5 Tesla, and a catalyst recovery rate of no less than 98%. The recovered catalyst is activated by soaking in a 10% hydrochloric acid solution for 30 minutes, followed by drying at 50 degrees Celsius. It can be recycled more than 20 times. The treated effluent undergoes multi-index testing, including an ammonia nitrogen detection limit of 0.1 mg / L, a total nitrogen detection limit of 1 mg / L, a pH value controlled between 6.5 and 7.5, and a suspended solids content not exceeding 30 mg / L. This ensures that all indicators meet the requirements of DB41 / 1135-2016 Chemical Industry Water Pollutant Indirect Discharge Standard, ultimately achieving safe wastewater discharge and efficient resource reuse.

[0048] Example 1:

[0049] A method for treating industrial wastewater rich in high concentrations of nitric acid includes the following steps:

[0050] 1. Adjust the pH of the wastewater to 3.0, add a supported catalyst (activated carbon support) at a Fe:Cu ratio of 3:1; add hydrogen peroxide (0.1 mol / L), react at 55℃ for 1.5 hours, so that the molar ratio of ammonia nitrogen (NH3-N) to nitrate ions approaches 1:1.3; effluent nitrite (NO2) - The concentration was increased to 2200 mg / L, while the ammonia nitrogen (NH3-N) concentration decreased to 780 mg / L.

[0051] 2. The effluent is introduced into an anaerobic reactor (SBR), and microbial activated sludge rich in short-cut denitrifying bacteria is added. Dissolved oxygen (DO) is controlled at <0.2 mg / L, temperature at 38℃, hydraulic retention time (HRT) at 15 hours, and C / N ratio at 0.5. The final effluent ammonia nitrogen (NH3-N) concentration is 12.3 mg / L, and total nitrogen (TN) concentration is 46.8 mg / L, meeting the "Indirect Discharge Standard for Water Pollutants in the Chemical Industry" (DB41 / 1135-2016).

[0052] Example 2:

[0053] A method for treating industrial wastewater rich in high concentrations of nitric acid includes the following steps:

[0054] 1. Adjust the pH of the wastewater to 4.0, add a supported catalyst (activated carbon support) at a Fe:Cu ratio of 3:1; add hydrogen peroxide (0.1 mol / L), react at 50℃ for 2 hours, so that the molar ratio of ammonia nitrogen (NH3-N) to nitrate ions approaches 1:1.3; effluent nitrite (NO2) - The concentration was increased to 2180 mg / L, while the concentration of ammonia nitrogen (NH3-N) decreased to 800 mg / L.

[0055] 2. The effluent is introduced into an anaerobic reactor (SBR), and microbial activated sludge rich in short-cut denitrifying bacteria is added. Dissolved oxygen (DO) is controlled at <0.2 mg / L, temperature at 35℃, hydraulic retention time (HRT) at 12 hours, and C / N ratio at 0.5. The final effluent ammonia nitrogen (NH3-N) concentration is 13.6 mg / L, and total nitrogen (TN) concentration is 48.5 mg / L, meeting the "Indirect Discharge Standard for Water Pollutants in the Chemical Industry" (DB41 / 1135-2016).

[0056] Example 3:

[0057] A method for treating industrial wastewater rich in high concentrations of nitric acid includes the following steps:

[0058] 1. Adjust the pH of the wastewater to 5.0, add a supported catalyst (activated carbon support) at a Fe:Cu ratio of 3:1; add hydrogen peroxide (0.1 mol / L), react at 45℃ for 2.5 hours, so that the molar ratio of ammonia nitrogen (NH3-N) to nitrate ions approaches 1:1.3; effluent nitrite (NO2) - The concentration was increased to 2060 mg / L, while the ammonia nitrogen (NH3-N) concentration decreased to 790 mg / L.

[0059] 2. The effluent is introduced into an anaerobic reactor (SBR), and microbial activated sludge rich in short-cut denitrifying bacteria is added. Dissolved oxygen (DO) is controlled at <0.2 mg / L, temperature at 30℃, hydraulic retention time (HRT) at 10 hours, and C / N ratio at 0.5. The final effluent ammonia nitrogen (NH3-N) concentration is 11.8 mg / L, and total nitrogen (TN) concentration is 46.5 mg / L, meeting the "Indirect Discharge Standard for Water Pollutants in the Chemical Industry" (DB41 / 1135-2016).

[0060] From the above, we can conclude that:

[0061] In this invention, the treatment efficiency of high-concentration nitric acid and ammonia nitrogen wastewater is significantly improved through the synergistic effect of catalytic oxidation and biological denitrification. In the catalytic oxidation stage, an Fe-Cu bimetallic catalyst is used to directionally regulate nitrogen speciation, oxidizing some ammonia nitrogen to nitrite while simultaneously reducing nitrate, leading to nitrite accumulation and significantly reducing the load on subsequent biological treatment. In the biological denitrification stage, a coupled pathway of short-cut denitrification and anaerobic ammonia oxidation is used, directly reacting ammonia as an electron donor with nitrite derivatives to generate nitrogen gas. This not only reduces carbon source requirements by more than 60% but also reduces sludge production by 40%, resulting in overall operating costs that are more than 50% lower than traditional processes, and no secondary pollutants are generated throughout the entire process.

[0062] In this invention, the catalyst is efficiently recovered and recycled more than 20 times through magnetic separation technology, reducing metal resource consumption and solid waste discharge. The treated effluent has a stable ammonia nitrogen concentration below 15 mg / L and a total nitrogen concentration below 50 mg / L, fully meeting the indirect emission standards of the chemical industry. The entire process breaks through the bottlenecks of traditional technologies, achieving efficient degradation and resource recycling of high-concentration nitric acid and ammonia nitrogen wastewater, providing a reliable solution for the green treatment of industrial wastewater.

[0063] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variations thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0064] The foregoing description enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for treating industrial wastewater rich in high concentrations of nitric acid, characterized in that: The following steps are required: S1: Adjust the pH of the industrial wastewater to the range of 3-5 to ensure the efficient execution of subsequent catalytic oxidation reactions; S2: A supported Fe-Cu bimetallic catalyst was added to the wastewater at a mass ratio of 3:1 for iron to copper, with activated carbon as the support, to enhance catalytic activity and stability. S3: Add hydrogen peroxide to the wastewater at a dosage of 0.1 mol / L to provide a source of hydroxyl radicals required for the oxidation reaction; S4: Under the temperature conditions of 45-55℃, the reaction is continued for 1.5-2.5 hours, so that the molar ratio of ammonia nitrogen to nitrate is close to 1:1.

3. At the same time, some ammonia nitrogen is oxidized to nitrite and nitrate is reduced to nitrite, forming nitrite accumulation. S5: Introduce the wastewater after catalytic oxidation treatment into the anaerobic bioreactor, add microbial activated sludge rich in short-range denitrifying bacteria, and start the biological denitrification process; S6: Control the dissolved oxygen concentration in the bioreactor to below 0.2 mg / L, maintain the temperature in the range of 30-38℃, and optimize the metabolic activity of microorganisms; S7: Adjust the hydraulic retention time to 10-15 hours and control the carbon-to-nitrogen ratio at 0.5 to promote the reduction of nitrite to nitric oxide by short-cut denitrifying bacteria; S8: Anaerobic ammonia-oxidizing bacteria use ammonia as an electron donor to react with nitric oxide to generate nitrogen gas, achieving simultaneous denitrification, and finally reducing the total nitrogen concentration to below 50 mg / L; S9: Recover the Fe-Cu bimetallic catalyst and recycle it at least 20 times to verify that the ammonia nitrogen concentration in the effluent is less than 15 mg / L and meets the emission standards of the chemical industry, thus completing the wastewater treatment; In step S1, the wastewater to be treated is introduced into an acid-resistant reaction tank, and a 10% sulfuric acid solution or a 5% sodium hydroxide solution is precisely added using a metering pump to strictly control the pH value within the range of 3.0-5.0; the adjustment rate is 0.5-1.0 L / min to ensure that the pH fluctuation does not exceed ±0.2; the acidic environment can activate the redox activity of the Fe-Cu catalyst and inhibit the formation of side reactions. In step S2, a catalyst is prepared with an iron to copper mass ratio of 3:1, and 20-30 g of supported catalyst is added per liter of wastewater; the particle size of the supported activated carbon is 1-2 mm, the specific surface area is 800-1000 m² / g, and the porosity is ≥85%; the loading of Fe³⁺ and Cu²⁺ in the catalyst is 12-15 wt% and 4-5 wt%, respectively. In step S7, the hydraulic retention time (HRT) is set to 12±2 hours, sodium acetate is used as an external carbon source, and it is added at a ratio of COD / N=0.5, with 200-300 mg of sodium acetate added per liter of wastewater; the COD / BOD5 ratio is controlled between 0.3 and 0.5 to ensure that the effective utilization rate of the carbon source is ≥90%.

2. The method for treating industrial wastewater rich in high concentrations of nitric acid as described in claim 1, characterized in that: In step S3, hydrogen peroxide (H2O2) is used as the oxidant and added at a standard of 0.1 mol / L, which is equivalent to adding 3.4 kg of 30% hydrogen peroxide stock solution per ton of wastewater; the addition rate is 0.2 L / min.

3. The method for treating industrial wastewater rich in high concentrations of nitric acid as described in claim 1, characterized in that: In step S4, the temperature is maintained at 45-55℃ and the stirring speed is 200-300 rpm in a mechanically stirred reactor for 1.5-2.5 hours. After the reaction, the ammonia nitrogen concentration drops from the initial 3000 mg / L to below 800 mg / L, the nitrate conversion rate is ≥85%, the nitrite accumulation reaches 2000-2200 mg / L, and the molar ratio of ammonia nitrogen to nitrate is stable at 1:1.25-1:1.

35.

4. The method for treating industrial wastewater rich in high concentrations of nitric acid as described in claim 1, characterized in that: In step S5, short-range denitrifying bacteria are added to the sequencing batch reactor (SBR) with a sludge concentration maintained at 5000-8000 mg / L and an inoculation ratio of 10%-15%. The effective volume of the reactor accounts for 80% of the total volume, the upward flow velocity is 0.5-1.0 m / h, the initial load is set at 0.3 kg N / m³ / d, and the load is increased by 20% every 48 hours until the design load of 0.8 kg N / m³ / d is reached.

5. The method for treating industrial wastewater rich in high concentrations of nitric acid as described in claim 1, characterized in that: In step S6, a nitrogen purging system is used to stabilize the dissolved oxygen concentration at 0.1-0.2 mg / L and maintain the oxidation-reduction potential below -200 mV; the temperature is controlled at 30-38℃ by a coil heat exchanger, of which 35-38℃ is the optimal activity range for anaerobic ammonia oxidizing bacteria; the temperature sensor collects data every 15 minutes with an adjustment accuracy of ±0.5℃.

6. The method for treating industrial wastewater rich in high concentrations of nitric acid as described in claim 1, characterized in that: In step S8, under anaerobic conditions, short-cut denitrifying bacteria convert 80%–85% of nitrite into NO, and anaerobic ammonia oxidizing bacteria use NH3 as an electron donor to remove nitrogen at a stoichiometric ratio of NH3:NO = 1:1.

3. The total nitrogen removal load reaches 0.5–0.8 kg N / m³ / d, the nitrite removal rate is ≥95%, and the final effluent total nitrogen concentration is stable at 40–50 mg / L, and the ammonia nitrogen concentration is ≤15 mg / L.

7. The method for treating industrial wastewater rich in high concentrations of nitric acid as described in claim 1, characterized in that: In step S9, a high gradient magnetic separation device is used to recover the Fe-Cu bimetallic catalyst, with a magnetic field strength ranging from 1.2 to 1.5 Tesla, and the catalyst recovery rate is not less than 98%. The recovered catalyst is activated by soaking in a 10% hydrochloric acid solution for 30 minutes.

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