Nitric acid wastewater denitrification treatment system and method based on electro-catalysis and membrane separation

Abstract

The invention provides a nitric acid wastewater denitrification treatment system and method based on electro-catalysis and membrane separation, and solves the problems of low nitric acid wastewater treatment efficiency, high cost and difficulty in up-to-standard discharge in the prior art. Through the synergistic effect of electro-catalysis pretreatment, chemical precipitation and DTRO membrane separation, synchronous and efficient removal of total nitrogen, COD and ammonia nitrogen is achieved, the removal rate of COD and the removal rate of ammonia nitrogen are both larger than 98%, the quality of treated water is far lower than the emission standard, environmental pollution is greatly reduced, and deep treatment of high-concentration nitric acid wastewater is achieved. A core device is an electro-catalytic reactor adopting a graphene electrode, the material has high conductivity and strong oxidation activity, the service life of the electrode is long, and the operation cost is reduced by about 30%. Meanwhile, through the near-neutral pH transition design, the use of chemical agents is reduced, secondary pollution is avoided, the effluent index of the treated wastewater is far lower than that of related standards, the treated wastewater can be recycled or safely discharged, and the method is particularly suitable for treating industrial wastewater with high pollution, high toxicity and poor biodegradability.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment technology, specifically relating to a denitrification treatment system and method for nitric acid wastewater based on electrocatalysis and membrane separation. Background Technology

[0002] Nitric acid wastewater is commonly found in industries such as metal pickling, electronics manufacturing, and chemical production. Its main components include nitric acid and ammonia nitrogen. This type of wastewater contains chemical oxygen demand (COD) and other organic and inorganic pollutants. It is characterized by high total nitrogen (TN) concentration, high COD content, high ammonia nitrogen concentration, high toxicity, and poor biodegradability. Therefore, the treatment of nitric acid wastewater has always been one of the challenges in the field of industrial wastewater treatment.

[0003] Traditional wastewater treatment methods, such as biological processes and Fenton oxidation, generally suffer from low efficiency, high operating costs, and difficulty in achieving synergistic removal of multiple pollutants. These technologies not only struggle to effectively degrade complex pollutants in wastewater but may also cause further environmental damage due to secondary pollution during the treatment process. Furthermore, single processes often fail to meet stringent emission standards, leaving treated wastewater with a potential threat to the surrounding environment.

[0004] In addition, nitrogen can also be removed through electrocatalytic reactions. In traditional nitric acid wastewater denitrification treatment, electrocatalytic reactors commonly use iron plates, titanium plates, copper-based or stainless steel as electrodes. However, the surface of iron plates is easily oxidized, leading to a reduction in active sites on the electrode surface, decreased conductivity, easy corrosion, and long replacement cycles. Moreover, the wastewater contains... , ,and Metal ions tend to deposit on the surface of iron plates, further hindering the contact between the electrode and wastewater and reducing the electrochemical performance of the electrode; while titanium plate electrodes have low nitrate reduction efficiency, resulting in high nitrate concentrations in the effluent, and are relatively expensive; copper-based electrodes... The low Faraday efficiency leads to a decrease in nitrate reduction efficiency, and The intermediate's adsorption energy on the copper surface is too strong, hindering the nitrate from adsorbing onto the copper surface. The gradual transformation; stainless steel electrodes are prone to hydrogen evolution reaction, which leads to a decrease in nitrate reduction efficiency as the voltage increases. In strongly acidic or highly oxidizing environments, their surface will be gradually corroded, affecting the service life of the electrodes; therefore, the conductivity of the electrode materials used in commonly used electrocatalytic reactors is unstable and they are prone to corrosion, resulting in short replacement cycles, high operating costs, and difficulty in removing high levels of pollutants, making it impossible to efficiently degrade the concentration of pollutants in the evaporated water.

[0005] Therefore, traditional treatment methods generally suffer from low treatment efficiency and are prone to secondary pollution. Furthermore, traditional electrode materials have unstable conductivity, are prone to corrosion, resulting in short replacement cycles, high operating costs, and difficulty in efficiently degrading pollutants in wastewater, thus failing to meet stringent emission standards. Summary of the Invention

[0006] This invention provides a nitrogen removal system and method for nitric acid wastewater based on electrocatalysis and membrane separation, aiming to solve the technical problems of low efficiency and high cost in the existing nitric acid wastewater treatment technology.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a nitric acid wastewater denitrification system based on electrocatalysis and membrane separation, comprising a pH adjustment tank, an electrocatalytic reactor, a reaction sedimentation tank and a DTRO membrane reactor, wherein the wastewater to be treated flows sequentially through the pH adjustment tank, the electrocatalytic reactor, the reaction sedimentation tank and the DTRO membrane reactor. The electrocatalytic reactor includes electrodes, a synthetic catalyst module, an electrolyzer, and a DC power supply; The electrode is a graphene bifunctional electrode synthesized using composite graphene carbonyl metal oxide electrode material; the synthesis catalyst module is composed of electrocatalytic cathode surface stacks with electrochemical reduction activity; the electrolytic cell is a bipolar electrolytic cell, which, together with the electrode, the synthesis catalyst module, and the DC power supply, performs an electrocatalytic reaction on nitric acid wastewater.

[0008] A preferred embodiment further includes a sludge collection tank, which is connected to a reaction sedimentation tank.

[0009] Based on the above scheme, the sludge contains various pollutants, heavy metal ions, flocculants and other components. The sludge collection pond collects these sludge in a concentrated manner to prevent secondary pollution.

[0010] A preferred embodiment further includes a filter press for dewatering and drying sludge, the filter press being connected to a sludge collection tank.

[0011] Based on the above scheme, the filter press uses mechanical pressure to forcibly separate the water in the sludge, transforming the sludge from a liquid or semi-fluid state into a solid dry sludge cake, reducing the water content of the sludge. It can be treated by incineration, landfill, or resource utilization. Moreover, the solid dry sludge cake is small in volume, which facilitates subsequent transportation and disposal.

[0012] In a preferred embodiment, the specific surface area of ​​the graphene bifunctional electrode is... conductivity .

[0013] Based on the above scheme, high specific surface area This means the electrode has more active sites, enabling it to fully contact pollutants in wastewater and increasing conductivity. This means that the electrode has superior conductivity, enabling it to conduct current more efficiently, reduce energy loss, and lower costs. In particular, it can more effectively promote the degradation and transformation of pollutants when treating high-concentration, complex-component nitric acid wastewater.

[0014] In a second aspect, the present invention provides a method for treating nitric acid wastewater using the nitric acid wastewater denitrification system based on electrocatalysis and membrane separation as described in the first aspect, comprising the following steps: S1. Electrocatalysis: The pH of the nitric acid wastewater is adjusted to 3-4. The pH-adjusted wastewater is then pumped into the electrolytic cell of the electrocatalytic reactor. The nitric acid wastewater contacts the electrodes and the synthesis catalyst module, at a current density of... Under these conditions, the electrocatalytic reaction was carried out for 50-70 minutes; S2, Chemical precipitation: The wastewater after electrocatalytic treatment is pumped into the reaction sedimentation tank, 8-12% sodium hydroxide solution is added to adjust the pH value of the wastewater to 7-9, and cationic PAM agent is added. After stirring evenly, flocculent precipitate is formed. The precipitate is removed and the supernatant overflows into the DTRO membrane reactor. S3. Membrane separation: Adjust the pressure regulating valve and use a high-pressure pump to pass the supernatant through the DTRO membrane in the DTRO membrane reactor at an operating pressure of 3-5 MPa, thereby retaining nitrate contaminants in the supernatant.

[0015] In a preferred embodiment, in step S2, the dosage of the cationic PAM agent is 1-3 mg / L.

[0016] In a preferred embodiment, in step S3, the molecular weight cutoff of the DTRO membrane is ≤200 Da.

[0017] Based on the above scheme, DTRO membranes with a molecular weight cutoff of ≤200 Da can effectively retain small molecule pollutants in wastewater, including nitrates, ammonia nitrogen, and organic matter, and are especially suitable for high-concentration nitric acid wastewater.

[0018] The beneficial effects of this invention are as follows: This invention provides a nitrogen removal system and method for nitric acid wastewater based on electrocatalysis and membrane separation. It integrates electrocatalysis, chemical precipitation, and DTRO membrane separation technologies to achieve simultaneous and efficient removal of total nitrogen, chemical oxygen demand (COD), and ammonia nitrogen, thereby improving wastewater treatment efficiency and effluent quality. The electrocatalytic reactor provided by this invention exhibits advantages such as high conductivity, superior electrocatalytic oxidation activity, low operating cost, and stable operation when treating nitric acid wastewater. Specific details are as follows: 1. The electrochemical reactor provided by this invention employs a bifunctional electrode synthesized from a composite graphene carbonyl metal oxide electrode material. This material not only possesses high conductivity but also exhibits superior electrocatalytic oxidation activity. Compared to traditional multi-metal oxide electrocatalytic anodes, this electrode does not require uniform coating of rare earth metals on both sides, thereby reducing material costs and preparation complexity. Furthermore, the replacement cycle of this electrode is far longer than that of other materials, significantly reducing subsequent operating costs while maintaining a high pollutant removal rate.

[0019] The synthesis catalyst module is composed of an electrocatalytic cathode plate with electrochemical reduction activity. This enables the system to effectively perform dehalogenation modification of halogenated hydrocarbons and electrodeposition removal of heavy metal ions at room temperature and pressure. The electrocatalytic cathode has good tolerance to fluctuations in water quality and temperature and is easy to automate.

[0020] In the pilot-scale effect analysis of electroplating wastewater treatment, this invention employs a bifunctional electrode and implements a bipolar electrochemical process to achieve superior treatment results. This avoids the limitations of unipolar electrolyzers, which are not suitable for all electrochemical oxidation processes. In particular, when using rotating electrode technology, the electrolyzer must possess excellent transmission characteristics to ensure continuous electrode rotation; while electrolyzers employing forced convection technology require sufficient pressure resistance to meet hydrodynamic requirements. Therefore, the bipolar electrolyzer with a bifunctional electrode design in this invention not only ensures uniform distribution of the electric field and water flow but also, combined with a DC power supply that provides appropriate waveform and frequency, improves the electrolytic treatment effect, optimizes the electroplating wastewater treatment process, increases pollutant removal efficiency, and ensures stable operation of the entire system.

[0021] 2. This invention achieves the reduction of total nitrogen (TN), chemical oxygen demand (COD), and ammonia nitrogen through electrocatalytic pre-degradation of macromolecular pollutants, chemical precipitation to remove metal ions, and then deep desalination via a DTRO membrane. Simultaneous and efficient removal. The experiment showed that the TN removal rate was >98% (from 4310 mg / L to <50 mg / L) and the COD removal rate was >99% (from 5120 mg / L to <30 mg / L). The effluent quality was significantly better than that of traditional treatment methods, thus improving treatment efficiency.

[0022] 3. The composite graphene carbonyl metal oxide electrode material has a long service life and low replacement frequency, significantly reducing electrode maintenance and replacement costs. Furthermore, the pH value of the electrocatalytic effluent is close to that required by the chemical precipitation stage, reducing the amount of reagents such as sodium hydroxide used, further lowering operating costs. Overall, operating costs are reduced by 30%, with electrode lifespan doubled, significantly reducing additional costs associated with electrode replacement.

[0023] 4. The entire treatment process of this invention generates no secondary pollution, and the effluent quality meets the Class B standard of GB / T31962-2015, allowing for direct reuse or safe discharge, thus being environmentally friendly. Through the synergistic effect of direct and indirect electrochemical oxidation-reduction, pollutants are modified, significantly improving the biodegradability of wastewater while reducing CODcr concentration and minimizing potential environmental hazards. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart of the process for treating nitric acid wastewater according to the present invention.

[0026] Figure 2 This is a schematic diagram of the nitric acid wastewater treatment system of the present invention.

[0027] Figure 3 This is a first schematic diagram of the electrocatalytic reactor structure in this invention.

[0028] Figure 4 This is a second schematic diagram of the electrocatalytic reactor structure in this invention.

[0029] Explanation of the labels in the diagram: 1-PLC control cabinet; 2-rectifier power supply; 3-water inlet; 4-electrolytic cell; 5-water outlet; 6-DTRO membrane system; 7-high pressure pump; 8-cleaning system; 9-upper tank; 10-spray inlet; 11-spray head; 12-exhaust port; 14-slag removal port. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the protection scope of the present invention.

[0031] Example 1: This embodiment provides a nitric acid wastewater denitrification system based on electrocatalysis and membrane separation, including a pH adjustment tank, an electrocatalytic reactor, a reaction sedimentation tank, and a DTRO membrane reactor, wherein the wastewater to be treated flows sequentially through the pH adjustment tank, the electrocatalytic reactor, the reaction sedimentation tank, and the DTRO membrane reactor. The electrocatalytic reactor includes electrodes, a synthetic catalyst module, an electrolyzer, and a DC power supply; The electrode is a graphene bifunctional electrode synthesized using composite graphene carbonyl metal oxide electrode material; the synthesis catalyst module is composed of electrocatalytic cathode surface stacks with electrochemical reduction activity; the electrolytic cell is a bipolar electrolytic cell, which, together with the electrode, the synthesis catalyst module, and the DC power supply, performs an electrocatalytic reaction on nitric acid wastewater.

[0032] The nitric acid wastewater denitrification system based on electrocatalysis and membrane separation also includes a sludge collection tank and a filter press for dewatering and drying the sludge. The sludge collection tank is connected to a reaction sedimentation tank, and the filter press is connected to the sludge collection tank.

[0033] Specifically, in the electrocatalytic reactor, wastewater undergoes an electrochemical reaction through a composite graphene carbonyl metal oxide electrode, where organic matter is oxidized and decomposed, and pollutants such as ammonia nitrogen and heavy metal ions are removed. The electrocatalytically treated wastewater flows into a reaction sedimentation tank, where cationic PAM reagents are added to promote the formation of flocs from suspended particles and some dissolved pollutants in the wastewater, thereby achieving solid-liquid separation.

[0034] The sludge produced in the reaction sedimentation tank is transported to a sludge collection tank. The purpose of the sludge collection tank is to temporarily store the sludge discharged from the reaction sedimentation tank for subsequent treatment. The sludge collection tank is connected to a filter press, which is used to dewater and dry the sludge. The filter press applies pressure to squeeze out the water from the sludge, forming a solid sludge cake, which facilitates the final disposal or resource utilization of the sludge.

[0035] The specific surface area of ​​the graphene bifunctional electrode is... conductivity .

[0036] See Figure 1-2 The system first undergoes automated control via PLC control cabinet 1. Then, the wastewater is converted to DC power by rectifier power supply 2 and enters an electrocatalytic reactor equipped with composite graphene carbonyl metal oxide electrodes. On the electrode surface, pollutants in the wastewater undergo electrochemical reactions and are converted into harmless substances. The treated water is discharged through the product water pipe, while unreacted pollutants are discharged through the concentrate pipe. The water sample then enters the DTRO membrane system 6 for further separation. The purified water separated by the DTRO membrane enters the product water tank, while the concentrated pollutants enter the concentrate tank. The system is also equipped with a cleaning system 8, including a cleaning inlet, a cleaning outlet, and a cleaning pump, to prevent membrane fouling and ensure stable system operation. The entire process is supported by a conveyor frame. The raw water tank collects raw water, the product water tank collects the treated product water, and the concentrate tank collects the concentrate separated by the DTRO membrane, thereby achieving efficient treatment of high-concentration nitric acid wastewater.

[0037] Example 2: This embodiment provides a method for treating nitric acid wastewater using the nitric acid wastewater denitrification system based on electrocatalysis and membrane separation as described in any of the embodiments in Example 1, including the following steps: S1. Electrocatalysis: The pH of the nitric acid wastewater is adjusted to 3-4. The pH-adjusted wastewater is then pumped into the electrolytic cell of the electrocatalytic reactor. The nitric acid wastewater contacts the electrodes and the synthesis catalyst module, at a current density of... Under these conditions, the electrocatalytic reaction was carried out for 50-70 minutes; S2, Chemical precipitation: The wastewater after electrocatalytic treatment is pumped into the reaction sedimentation tank, 8-12% sodium hydroxide solution is added to adjust the pH value of the wastewater to 7-9, and cationic PAM agent is added. After stirring evenly, flocculent precipitate is formed. The precipitate is removed and the supernatant overflows into the DTRO membrane reactor. S3. Membrane separation: Adjust the pressure regulating valve and use a high-pressure pump to pass the supernatant through the DTRO membrane in the DTRO membrane reactor at an operating pressure of 3-5 MPa, thereby retaining nitrate contaminants in the supernatant.

[0038] See Figure 3-4 The electrocatalytic process in step S1 is as follows: Nitric acid wastewater is first introduced into the system, entering the upper tank 9 of the electrocatalytic reactor through the spray inlet 10 and spray head 11 on the left. The electrocatalytic reactor consists of multiple parallel electrolytic cells 4, each containing a composite graphene carbonyl metal oxide electrode. These electrodes have high conductivity and high catalytic activity, used to degrade organic pollutants and ammonia nitrogen in the wastewater. The synthesis catalytic module is arranged in the form of parallel plates to ensure that the wastewater can fully contact the electrode surface, thereby improving the electrocatalytic efficiency. The electrocatalytic reactor is connected to a DC power supply via a cable, which provides the necessary DC power to drive the electrocatalytic reaction. Under the action of the electric field, the organic pollutants and ammonia nitrogen in the wastewater undergo oxidation-reduction reactions on the electrode surface, converting into harmless or low-toxic substances such as nitrogen, water, and carbon dioxide. The wastewater after electrocatalytic treatment is discharged from the outlet 5 of the electrocatalytic reactor and enters the subsequent DTRO membrane system 6. Gases produced during the electrocatalytic process, such as oxygen or nitrogen, are discharged through the exhaust port 12 at the top of the electrolytic cell 4, while waste residue is discharged through the slag removal port 14.

[0039] In step S2, the dosage of the cationic PAM agent is 1-3 mg / L.

[0040] In step S3, the molecular weight cutoff of the DTRO membrane is ≤200 Da.

[0041] See Figure 2The specific process of step S3 is as follows: Nitric acid wastewater is first treated by electrocatalysis and then introduced into the DTRO membrane system 6 through the inlet pipe by a high-pressure pump 7. Within the system, the wastewater flows through multiple parallel membrane tubes. Under pressure, water molecules and small molecules with low solubility can permeate through the membrane, while larger pollutants, such as suspended solids, organic matter, and most salts, are retained. The clean permeate (i.e., membrane effluent) flows out from the other end of the module and is collected in the product water tank. This purified water can be reused or discharged. Simultaneously, the concentrate containing pollutants (concentrate) is discharged from the other end of the module and guided to the concentrate tank for further treatment. The entire process achieves effective separation of water and pollutants in the wastewater, ensuring that the effluent quality meets relevant standards.

[0042] The invention will be further explained and illustrated below with reference to specific experiments: I. Experimental Objective: To evaluate and verify the efficiency and effectiveness of combined electrocatalysis and membrane separation technologies for denitrification of nitric acid wastewater in order to meet stringent emission standards.

[0043] II. Materials and Equipment The nitric acid wastewater sample had a pH of 2-4, a CODcr of 5120 mg / L, an ammonia nitrogen of 768 mg / L, and a total nitrogen of 4310 mg / L.

[0044] An electrocatalytic reactor equipped with a composite graphene carbonyl metal oxide electrode.

[0045] DTRO membrane system, pH adjustment tank, reaction sedimentation tank, sludge collection tank and filter press.

[0046] III. Test Procedure 1. System Settings (1) See Figure 1 The wastewater is pumped into the nitric acid wastewater pretreatment collection tank.

[0047] (2) Connect the DC power supply to the electrocatalytic reduction reactor.

[0048] (3) Connect the DTRO membrane system to the membrane cleaning system.

[0049] (4) Ensure that all equipment and pipes are properly connected and leak-free.

[0050] 2. Electrocatalytic treatment stage (1) Adjust the pH of the wastewater to 3.5.

[0051] (2) Start the electrocatalytic reactor and carry out the electrocatalytic reaction for 1 hour.

[0052] (3) Record COD, TN, The concentration change.

[0053] 3. Chemical precipitation stage (1) Introduce the wastewater after electrocatalytic treatment into the reaction sedimentation tank.

[0054] (2) Adjust the pH of the wastewater to 8 and add 2 mg / L PAM.

[0055] (3) Stir to form a flocculent precipitate and collect the supernatant.

[0056] 4. DTRO membrane treatment stage (1) Introduce the supernatant into the DTRO membrane reactor.

[0057] (2) Adjust the pressure regulating valve and use a high-pressure pump to pass the supernatant through the DTRO membrane.

[0058] (3) Collect membrane effluent and concentrate.

[0059] 5. Sludge Treatment Stage (1) Discharge the sludge generated in the reaction sedimentation tank to the sludge collection tank.

[0060] (2) The sludge is transported to a filter press for dewatering and drying.

[0061] 6. Water quality analysis (1) Collect water samples at each treatment stage.

[0062] (2) Analyze the TN, COD and... in the water sample concentration.

[0063] IV. Test Results Raw water: CODcr 5120 mg / L; ammonia nitrogen 768 mg / L; total nitrogen 4310 mg / L.

[0064] Electrocatalytic effluent: CODcr 2240 mg / L; ammonia nitrogen 320 mg / L; total nitrogen 2630 mg / L.

[0065] Membrane filtration effluent: CODcr 26 mg / L; ammonia nitrogen 17.2 mg / L; total nitrogen 48.6 mg / L.

[0066] VI. Conclusion Experimental results show that the nitric acid wastewater denitrification treatment system based on electrocatalysis and membrane separation can effectively remove COD, ammonia nitrogen, and total nitrogen from wastewater. After treatment, the effluent quality meets the Class B standard of GB / T31962-2015 and can be reused or safely discharged. Specifically: 1. TN removal rate >98% (from 4310 mg / L to <50 mg / L).

[0067] 2. COD removal rate > 99%.

[0068] 3. Composite graphene carbonyl metal oxide electrodes achieve a 30% reduction in operating costs through improved structural stability, enhanced catalytic activity, and reduced energy consumption.

[0069] Specifically, operating costs mainly consist of electrode replacement costs and energy consumption costs. Electrode replacement costs account for approximately 20% of total operating costs, while energy consumption costs account for 80%.

[0070] (1) Reduced electrode replacement cost: The lifespan of the composite graphene carbonyl metal oxide electrode is about twice that of the traditional electrode, extending the replacement interval from about 2 years to 4 years. As the electrode replacement cost is directly reduced by 50%, the proportion of electrode replacement cost in the operating cost is reduced from 20% to 10%.

[0071] (2) Reduced energy consumption costs: Due to the low resistance and high conductivity of the composite graphene carbonyl metal oxide electrode, energy consumption can be reduced by about 10%. In addition, due to the improved structural stability of the electrode, maintenance and downtime losses are also reduced by 20%-30%.

[0072] Therefore, taking into account the reduction in electrode replacement costs and energy consumption costs, the overall operating cost can be reduced by more than 30%. This cost reduction stems not only from the high efficiency of the electrode material itself, but also from its enhanced stability, which reduces maintenance and downtime.

[0073] In summary, the high-concentration nitric acid wastewater denitrification system and method of this invention, by employing a composite graphene carbonyl metal oxide electrode and DTRO membrane technology, achieves a total nitrogen removal rate of over 98% and a COD removal rate of over 99%, significantly reducing operating costs by approximately 30%, while ensuring that the treated water quality meets stringent discharge standards, allowing for direct reuse or safe discharge. This system also possesses advantages such as environmental friendliness, high automation, strong adaptability, and ease of control, providing an efficient, economical, and sustainable solution for the treatment of high-concentration nitric acid wastewater.

[0074] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. A nitric acid wastewater denitrification system based on electrocatalysis and membrane separation, characterized in that, It includes a pH adjustment tank, an electrocatalytic reactor, a reaction sedimentation tank, and a DTRO membrane reactor, and the wastewater to be treated flows through the pH adjustment tank, the electrocatalytic reactor, the reaction sedimentation tank, and the DTRO membrane reactor in sequence. The electrocatalytic reactor includes electrodes, a synthetic catalyst module, an electrolyzer, and a DC power supply; The electrode is a graphene bifunctional electrode synthesized using composite graphene carbonyl metal oxide electrode material; the synthesis catalyst module is composed of electrocatalytic cathode surface stacks with electrochemical reduction activity; the electrolytic cell is a bipolar electrolytic cell, which, together with the electrode, the synthesis catalyst module, and the DC power supply, performs an electrocatalytic reaction on nitric acid wastewater.

2. The nitric acid wastewater denitrification system based on electrocatalysis and membrane separation according to claim 1, characterized in that: It also includes a sludge collection tank, which is connected to a reaction sedimentation tank.

3. The nitric acid wastewater denitrification system based on electrocatalysis and membrane separation according to claim 1, characterized in that: It also includes a filter press for dewatering and drying sludge, the filter press being connected to a sludge collection tank.

4. The nitric acid wastewater denitrification system based on electrocatalysis and membrane separation according to claim 1, characterized in that: The specific surface area of ​​the graphene bifunctional electrode conductivity .

5. A method for treating nitric acid wastewater using the nitric acid wastewater denitrification system based on electrocatalysis and membrane separation as described in claim 1, characterized in that, Includes the following steps: S1. Electrocatalysis: The pH of the nitric acid wastewater is adjusted to 3-4. The pH-adjusted wastewater is then pumped into the electrolytic cell of the electrocatalytic reactor. The nitric acid wastewater contacts the electrodes and the synthesis catalyst module, at a current density of... Under these conditions, the electrocatalytic reaction was carried out for 50-70 minutes; S2, Chemical precipitation: The wastewater after electrocatalytic treatment is pumped into the reaction sedimentation tank, 8-12% sodium hydroxide solution is added to adjust the pH value of the wastewater to 7-9, and cationic PAM agent is added. After stirring evenly, flocculent precipitate is formed. The precipitate is removed and the supernatant overflows into the DTRO membrane reactor. S3. Membrane separation: Adjust the pressure regulating valve and use a high-pressure pump to pass the supernatant through the DTRO membrane in the DTRO membrane reactor at an operating pressure of 3-5 MPa, thereby retaining nitrate contaminants in the supernatant.

6. The nitric acid wastewater treatment method according to claim 5, based on an electrocatalytic and membrane separation-based nitric acid wastewater denitrification system, is characterized in that: In step S2, the dosage of the cationic PAM agent is: .

7. The nitric acid wastewater treatment method according to claim 5, based on an electrocatalytic and membrane separation-based nitric acid wastewater denitrification system, is characterized in that: In step S3, the molecular weight cutoff of the DTRO membrane is ≤200 Da.

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