Method for treating industrial wastewater rich in high-concentration nitric acid

Abstract

The invention discloses a method for treating industrial wastewater rich in high-concentration nitric acid, and belongs to the technical field of range, and in the method, the treatment efficiency of high-concentration nitric acid and ammonia nitrogen wastewater is remarkably improved through the synergistic effect of catalytic oxidation and biological denitrification. In the catalytic oxidation stage, a Fe-Cu bimetallic catalyst is adopted to directionally regulate and control the nitrogen form, nitrate is reduced while part of ammonia nitrogen is oxidized into nitrite, nitrosation accumulation is formed, and the follow-up biological treatment load is greatly reduced. In the biological denitrification stage, through a short-cut denitrification and anaerobic ammonia oxidation coupling path, ammonia is directly used as an electron donor to react with nitrite derivatives to generate nitrogen, not only is the carbon source demand reduced by 60% or above, but also the sludge yield is reduced by 40%, the comprehensive operation cost is saved by 50% or above compared with that of a traditional process, and no secondary pollutants are generated in the whole process.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial wastewater treatment, and specifically relates to a method for treating industrial wastewater rich in high-concentration nitric acid. Background Art

[0002] The acid etching process in the glass processing field will produce problems of high-concentration nitric acid and high-concentration ammonia nitrogen during the glass etching process. The ammonia nitrogen concentration often reaches more than 3000 mg / L, bringing great difficulties to the subsequent industrial wastewater treatment work.

[0003] However, the traditional treatment of industrial wastewater with coexisting high-concentration ammonia nitrogen and nitric acid has the following problems: the chemical method has high costs and complex by-products; the biological method is inhibited by high-concentration nitric acid, has a large demand for denitrification carbon sources, and it is difficult to achieve discharge standards; the physical method is prone to blockage and cannot completely degrade pollutants. Summary of the Invention

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

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

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

[0007] S2: Add a supported Fe-Cu bimetallic catalyst to the wastewater according to the mass ratio of iron to copper of 3:1, and the carrier is activated carbon to enhance the catalytic activity and stability.

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

[0009] S4: Under the temperature condition of 45-55 °C, continuously react for 1.5-2.5 hours to make the molar ratio of ammonia nitrogen to nitrate radical approach 1:1.3, and at the same time oxidize part of the ammonia nitrogen to nitrite and reduce nitrate to nitrite to form nitrification accumulation.

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

[0011] S6: Control the dissolved oxygen concentration in the bioreactor to be lower than 0.2 mg / L, maintain the temperature in the range of 30-38 °C, and optimize the microbial metabolic activity.

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

[0013] S8: Use anaerobic ammonium oxidation bacteria with ammonia as the electron donor to react with nitric oxide to generate nitrogen gas, achieve synchronous nitrogen removal, and finally reduce the total nitrogen concentration to below 50 mg / L.

[0014] S9: Recover the Fe-Cu bimetallic catalyst and recycle it at least 20 times, verify that the ammonia nitrogen concentration in the effluent is below 15 mg / L and meets the chemical industry discharge standard, and complete 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 sulfuric acid solution with a concentration of 10% or a sodium hydroxide solution with a concentration of 5% is accurately added through a metering pump, and the pH value is strictly controlled 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 generation of side reactions.

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

[0017] In a preferred embodiment, in step S3, hydrogen peroxide (H2O2) is used as the oxidant and added according to the 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 dosing rate is 0.2 L / min, and a static mixer is used to ensure full contact between the reagent and the wastewater, and avoid ineffective decomposition caused by too high local concentration.

[0018] In a preferred embodiment, in step S4, in a mechanical stirring reactor, maintain the temperature at 45 - 55 °C (temperature control accuracy ±1 °C), the stirring speed at 200 - 300 rpm, and the reaction time at 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 ≥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.

[0019] In a preferred embodiment, in step S5, dominant strains of shortcut denitrifying bacteria are added to the sequencing batch reactor (SBR), the sludge concentration is maintained at 5000 - 8000 mg / L, and the inoculation ratio is 10% - 15%. The effective volume ratio of the reactor is 80%, the upflow velocity is 0.5 - 1.0 m / h, and the initial load is set at 0.3 kg N / m 3 / d, and it is increased by 20% every 48 hours until the design load of 0.8 kg N / m 3 / d is reached.

[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 the oxidation-reduction potential (ORP) is maintained below -200 mV. The temperature is controlled at 30 - 38 °C through a coil heat exchanger, where 35 - 38 °C is the optimal activity range for anaerobic ammonium oxidation bacteria. The temperature sensor collects data every 15 minutes, and the regulation accuracy is ±0.5 °C.

[0021] In a preferred embodiment, 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. 200 - 300 mg of sodium acetate (purity ≥ 99%) is 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, shortcut denitrifying bacteria convert 80% - 85% of nitrite into NO, and anaerobic ammonium oxidation bacteria use NH3 as an electron donor for nitrogen removal according to the stoichiometric ratio of NH3:NO = 1:1.3. The total nitrogen removal load reaches 0.5 - 0.8 kg N / m 3 / d, the nitrite removal rate is ≥ 95%, the total nitrogen concentration of the final effluent is stabilized at 40 - 50 mg / L, and the ammonia nitrogen concentration is ≤ 15 mg / L.

[0023] In a preferred embodiment, in step S9, a high-gradient magnetic separation device is used to recover the Fe-Cu bimetallic catalyst, the magnetic field strength ranges from 1.2 to 1.5 Tesla, and the catalyst recovery rate is not less than 98%. The recovered catalyst is soaked and activated in a 10% hydrochloric acid solution for 30 minutes, and then dried at 50 °C. The cumulative number of recycling times can reach more than 20 times. The treated effluent needs to be tested for multiple indicators, including the ammonia nitrogen detection limit of 0.1 mg / L, the total nitrogen detection limit of 1 mg / L, the pH value controlled between 6.5 and 7.5, and the suspended solid content not exceeding 30 mg / L, to ensure that all indicators meet the requirements of the indirect discharge standard for water pollutants in the chemical industry DB41 / 1135 - 2016, and finally achieve the safe discharge of wastewater and the efficient reuse of resources.

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

[0025] 1. In the present invention, through the synergistic effect of catalytic oxidation and biological denitrification, the treatment efficiency of high-concentration nitric acid and ammonia-nitrogen wastewater is significantly improved. In the catalytic oxidation stage, the Fe-Cu bimetallic catalyst is used to directionally regulate the nitrogen form, oxidizing part of the ammonia nitrogen to nitrite while reducing nitrate, forming nitrite accumulation and greatly reducing the subsequent biological treatment load. In the biological denitrification stage, through the coupling path of short-cut denitrification and anaerobic ammonium oxidation, ammonia is directly used as the electron donor to react with nitrite derivatives to generate nitrogen gas, which not only reduces the carbon source demand by more than 60%, but also reduces the sludge production by 40%. The comprehensive operation cost is saved by more than 50% compared with the traditional process, and no secondary pollutants are generated throughout the process.

[0026] 2. In the present invention, the catalyst is efficiently recovered and recycled more than 20 times through magnetic separation technology, reducing the consumption of metal resources and solid waste emissions; the ammonia-nitrogen concentration in the treated effluent is stably lower than 15 mg / L, and the total nitrogen concentration is lower than 50 mg / L, fully meeting the indirect discharge standard of the chemical industry. The whole process breaks through the traditional technical bottleneck, realizes the efficient degradation and resource recycling of high-concentration nitric acid and ammonia-nitrogen wastewater, and provides a reliable solution for the green treatment of industrial wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic flow principle diagram of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

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

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

[0031] S2: Add a supported Fe-Cu bimetallic catalyst to the wastewater according to the mass ratio of iron to copper of 3:1, and the carrier is activated carbon to enhance the catalytic activity and stability.

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

[0033] S4: Under the temperature condition of 45 - 55 °C, react continuously for 1.5 - 2.5 hours to make the molar ratio of ammonia nitrogen to nitrate approach 1:1.3. At the same time, oxidize part of the ammonia nitrogen to nitrite and reduce nitrate to nitrite to form nitrite accumulation.

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

[0035] S6: Control the dissolved oxygen concentration in the bioreactor to be lower than 0.2 mg / L, maintain the temperature in the range of 30 - 38 °C, and optimize the microbial metabolic activity.

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

[0037] S8: Use anaerobic ammonium oxidation bacteria to take ammonia as the electron donor and react with nitric oxide to generate nitrogen gas, realizing synchronous nitrogen removal. Finally, the total nitrogen concentration is reduced to below 50 mg / L.

[0038] S9: Recover the Fe-Cu bimetallic catalyst and recycle it at least 20 times. Verify that the ammonia nitrogen concentration in the effluent is lower than 15 mg / L and meets the chemical industry discharge standard to complete the wastewater treatment.

[0039] In step S1, introduce the wastewater to be treated into the acid-resistant reaction tank, accurately add a sulfuric acid solution with a concentration of 10% or a sodium hydroxide solution with a concentration of 5% through a metering pump, and 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 at the same time inhibit the generation of side reactions.

[0040] In step S2, prepare the catalyst according to the mass ratio of iron to copper of 3:1, and add 20 - 30 g of the supported catalyst per liter of wastewater. The particle size of the carrier activated carbon is 1 - 2 mm, the specific surface area is 800 - 1000 m 2 / g, and the porosity is ≥85%. The loadings of Fe 3 + and Cu 2 + are 12 - 15 wt% and 4 - 5 wt% respectively, and it is prepared by the impregnation-calcination method. The calcination temperature is controlled at 450 - 500 °C to maintain the metal activity.

[0041] In step S3, use hydrogen peroxide (H2O2) as the oxidant and add it according to the 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 feeding rate is 0.2 L / min, and a static mixer is used to ensure full contact between the reagent and the wastewater to avoid ineffective decomposition caused by too high local concentration.

[0042] In step S4, in a mechanical stirring reactor, maintain the temperature at 45 - 55 °C (temperature control accuracy ±1 °C), the stirring speed at 200 - 300 rpm, and the reaction time at 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 ≥ 85%, the nitrite accumulation reaches 2000 - 2200 mg / L, and the molar ratio of ammonia nitrogen to nitrate stabilizes at 1:1.25 - 1:1.35.

[0043] In step S5, add the dominant strain of short-cut denitrifying bacteria to the sequencing batch reactor (SBR). Maintain the sludge concentration at 5000 - 8000 mg / L and the inoculation ratio at 10% - 15%. The effective volume ratio of the reactor is 80%, the upflow velocity is 0.5 - 1.0 m / h, and the initial load is set at 0.3 kg N / m 3 / d, and increase it by 20% every 48 hours until the design load of 0.8 kg N / m 3 / d is reached.

[0044] In step S6, use a nitrogen purging system to stabilize the dissolved oxygen concentration at 0.1 - 0.2 mg / L, and maintain the oxidation-reduction potential (ORP) below -200 mV. Control the temperature at 30 - 38 °C through a coil heat exchanger, where 35 - 38 °C is the optimal activity range for anaerobic ammonium oxidation bacteria. The temperature sensor collects data every 15 minutes, and the regulation accuracy is ±0.5 °C.

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

[0046] In step S8, under anaerobic conditions, short-cut denitrifying bacteria convert 80% - 85% of nitrite into NO, and anaerobic ammonium oxidation bacteria use NH3 as the electron donor to carry out denitrification according to the stoichiometric ratio of NH3:NO = 1:1.3. The total nitrogen removal load reaches 0.5 - 0.8 kg N / m 3 / d, the nitrite removal rate ≥ 95%, and the total nitrogen concentration of the final effluent stabilizes at 40 - 50 mg / L, and the ammonia nitrogen concentration ≤ 15 mg / L.

[0047] In step S9, a high-gradient magnetic separation device is used to recover the Fe-Cu bimetallic catalyst. The magnetic field strength ranges from 1.2 to 1.5 Tesla, and the catalyst recovery rate is not less than 98%. The recovered catalyst is soaked and activated in a hydrochloric acid solution with a concentration of 10% for 30 minutes, and then dried at 50 degrees Celsius. The cumulative number of recycling times can reach 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 solid content not exceeding 30 mg / L, to ensure that all indicators meet the requirements of the Indirect Discharge Standard for Water Pollutants in the Chemical Industry (DB41 / 1135-2016), ultimately achieving the safe discharge of wastewater and the efficient reuse of resources.

[0048] Example 1:

[0049] A method for treating industrial wastewater rich in high-concentration nitric acid, comprising the following steps:

[0050] 1. Adjust the pH of the wastewater to 3.0, and add a supported catalyst (with activated carbon as the carrier) according to Fe:Cu = 3:1; add hydrogen peroxide (dosage 0.1 mol / L), and react at 55 °C for 1.5 hours to make the molar ratio of ammonia nitrogen NH3-N to nitrate ions approach 1:1.3; the concentration of nitrite NO2 in the effluent - increases to 2200 mg / L, and the concentration of ammonia nitrogen NH3-N decreases to 780 mg / L.

[0051] 2. Introduce the effluent into an anaerobic reactor (SBR), and add microbial activated sludge rich in short-cut denitrifying bacteria. Control the dissolved oxygen DO < 0.2 mg / L, the temperature at 38 °C, the hydraulic retention time HRT at 15 hours, and the C / N carbon-nitrogen ratio at 0.5; the final effluent has an ammonia nitrogen NH3-N concentration of 12.3 mg / L and a total nitrogen TN concentration of 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-concentration nitric acid, comprising the following steps:

[0054] 1. Adjust the pH of the wastewater to 4.0, and add a supported catalyst (with activated carbon as the carrier) according to Fe:Cu = 3:1; add hydrogen peroxide (dosage 0.1 mol / L), and react at 50 °C for 2 hours to make the molar ratio of ammonia nitrogen NH3-N to nitrate ions approach 1:1.3; the concentration of nitrite NO2 in the effluent - increases to 2180 mg / L, and the concentration of ammonia nitrogen NH3-N decreases to 800 mg / L.

[0055] 2. Introduce the effluent into an anaerobic reactor (SBR), and add microbial activated sludge rich in short-cut denitrifying bacteria. Control the dissolved oxygen DO < 0.2 mg / L, the temperature at 35 °C, the hydraulic retention time HRT at 12 hours, and the C / N carbon-nitrogen ratio at 0.5; the final effluent ammonia nitrogen NH₃-N concentration is 13.6 mg / L, and the 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-concentration nitric acid, comprising the following steps:

[0058] 1. Adjust the pH of the wastewater to 5.0, and add a supported catalyst (with activated carbon as the carrier) according to Fe:Cu = 3:1; add hydrogen peroxide (dosage 0.1 mol / L), and react at 45 °C for 2.5 hours to make the molar ratio of ammonia nitrogen NH₃-N to nitrate ions approach 1:1.3; the effluent nitrite NO₂ - concentration is increased to 2060 mg / L, and the ammonia nitrogen NH₃-N concentration is reduced to 790 mg / L.

[0059] 2. Introduce the effluent into an anaerobic reactor (SBR), and add microbial activated sludge rich in short-cut denitrifying bacteria. Control the dissolved oxygen DO < 0.2 mg / L, the temperature at 30 °C, the hydraulic retention time HRT at 10 hours, and the C / N carbon-nitrogen ratio at 0.5; the final effluent ammonia nitrogen NH₃-N concentration is 11.8 mg / L, and the 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] It can be known from the above:

[0061] In the present invention, through the synergistic effect of catalytic oxidation and biological denitrification, the treatment efficiency of high-concentration nitric acid and ammonia nitrogen wastewater is significantly improved. In the catalytic oxidation stage, the Fe-Cu bimetallic catalyst is used to directionally regulate the nitrogen form, oxidize part of the ammonia nitrogen to nitrite while reducing nitrate, forming nitrite accumulation and greatly reducing the subsequent biological treatment load. In the biological denitrification stage, through the coupling path of short-cut denitrification and anaerobic ammonia oxidation, ammonia is directly used as an electron donor to react with nitrite derivatives to generate nitrogen gas, which not only reduces the carbon source demand by more than 60%, but also reduces the sludge production by 40%. The comprehensive operating cost is saved by more than 50% compared with the traditional process, and no secondary pollutants are generated throughout the process.

[0062] In the present invention, the catalyst is efficiently recovered and recycled more than 20 times through magnetic separation technology, reducing the consumption of metal resources and the discharge of solid waste. The ammonia nitrogen concentration in the treated effluent is stably lower than 15 mg / L, and the total nitrogen concentration is lower than 50 mg / L, fully meeting the indirect discharge standard of the chemical industry. The entire process breaks through the bottleneck of traditional technologies, realizes the efficient degradation and resource recycling of high-concentration nitric acid and ammonia nitrogen wastewater, and provides a reliable solution for the green treatment of industrial wastewater.

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

[0064] The above description enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not 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-concentration nitric acid, characterized in that: It includes the following steps: S1: Adjust the pH value of the industrial wastewater to the range of 3 - 5 to ensure the efficient progress of the subsequent catalytic oxidation reaction; S2: Add the supported Fe-Cu bimetallic catalyst to the wastewater according to the mass ratio of iron to copper of 3:

1. The carrier is activated carbon to enhance the catalytic activity and stability; S3: Add hydrogen peroxide to the wastewater, and the dosage is 0.1 mol / L to provide the source of hydroxyl radicals required for the oxidation reaction; S4: Under the temperature condition of 45 - 55 °C, continuously react for 1.5 - 2.5 hours to make the molar ratio of ammonia nitrogen to nitrate approach 1:1.

3. At the same time, oxidize part of the ammonia nitrogen to nitrite and reduce nitrate to nitrite to form nitrite accumulation; S5: Introduce the wastewater treated by catalytic oxidation into the anaerobic bioreactor, add the microbial activated sludge rich in short-cut denitrifying bacteria to initiate the biological nitrogen removal process; S6: Control the dissolved oxygen concentration in the bioreactor to be lower than 0.2 mg / L, and maintain the temperature in the range of 30 - 38 °C to optimize the microbial metabolic activity; S7: Adjust the hydraulic retention time to 10 - 15 hours, and control the carbon-nitrogen ratio at 0.5 to promote the short-cut denitrifying bacteria to reduce nitrite to nitric oxide; S8: Use anaerobic ammonium oxidation bacteria to use ammonia as an electron donor to react with nitric oxide to generate nitrogen gas, realizing synchronous nitrogen removal, 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. Verify that the ammonia nitrogen concentration in the effluent is lower than 15 mg / L and meets the chemical industry discharge standard to complete the wastewater treatment.

2. The method for treating industrial wastewater rich in high-concentration nitric acid according to claim 1, characterized in that: In step S, 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 accurately added through 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 generation of side reactions.

3. The method for treating industrial wastewater rich in high-concentration nitric acid according to claim 1, characterized in that: In the step S2, a catalyst is prepared with a mass ratio of iron to copper of 3:1, and 20-30 g of the supported catalyst is added to each liter of wastewater; the carrier activated carbon has a particle size of 1-2 mm, a specific surface area of 800-1000 m 2 / g, and a porosity of ≥85%; the loadings of Fe 3 + and Cu 2 + are 12-15 wt% and 4-5 wt% respectively.

4. A method for treating industrial wastewater rich in high-concentration nitric acid as described in claim 1, characterized in that: In step S3, hydrogen peroxide (H2O2) is used as the oxidant and added according to the 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 feeding rate is 0.2 L / min.

5. A method for treating industrial wastewater rich in high-concentration nitric acid as described in claim 1, characterized in that: In step S4, in a mechanical stirring reactor, maintain the temperature at 45 - 55 °C (temperature control accuracy ±1 °C), the stirring speed at 200 - 300 rpm, and the reaction time at 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 ≥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.

6. The method for treating industrial wastewater rich in high-concentration nitric acid according to claim 1, characterized in that: In the step S5, dominant strains of short-cut denitrifying bacteria are added to the sequencing batch reactor, the sludge concentration is maintained at 5000-8000 mg / L, and the inoculation ratio is 10%-15%; the effective volume ratio of the reactor is 80%, the upward flow velocity is 0.5-1.0 m / h, and the initial load is set at 0.3 kg N / m 3 / d, and it is increased by 20% every 48 hours until the design load of 0.8 kg N / m 3 / d is reached.

7. A method for treating industrial wastewater rich in high-concentration nitric acid as described in claim 1, characterized in that: In step S6, use a nitrogen purging system to stabilize the dissolved oxygen concentration at 0.1 - 0.2 mg / L, and maintain the oxidation-reduction potential below -200 mV; control the temperature at 30 - 38 °C through a coil heat exchanger, where 35 - 38 °C is the optimal activity range for anaerobic ammonium oxidation bacteria; the temperature sensor collects data every 15 minutes, and the control accuracy is ±0.5 °C.

8. The method for treating industrial wastewater rich in high-concentration nitric acid according to claim 1, characterized in that: In the step S7, the hydraulic retention time (HRT) is set to be 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%.

9. The method for treating industrial wastewater rich in high-concentration nitric acid according to claim 1, characterized in that: In step S8, under anaerobic conditions, short-cut denitrifying bacteria convert 80% - 85% of nitrite into NO, and anaerobic ammonium oxidation bacteria use NH3 as the electron donor to perform nitrogen removal according to the stoichiometric ratio of NH3:NO = 1:1.3; the total nitrogen removal load reaches 0.5 - 0.8 kg N / m 3 / d, the nitrite removal rate is ≥95%, the total nitrogen concentration of the final effluent is stable at 40 - 50 mg / L, and the ammonia nitrogen concentration is ≤15 mg / L.

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

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