A method of treating nitrogen pollutants with a microbial fuel cell

Abstract

The application discloses a method for treating nitrogen pollutants by using a microbial fuel cell, and belongs to the technical field of sewage treatment, and comprises the following steps: S1, establishing a nitrogen removal operation system of the microbial fuel cell and obtaining initial operation parameters; S2, establishing a dynamic matching relationship between electron supply capacity and nitrogen pollutant conversion demand according to the initial operation parameters; S3, adjusting the operation condition of the microbial fuel cell according to the dynamic matching relationship and the nitrogen pollutant conversion state; S4, implementing closed-loop control of the nitrogen removal process according to the operation condition and electrochemical feedback information; and S5, determining the end point of the nitrogen removal and implementing self-recovery operation of the system based on the closed-loop control process. The method for treating nitrogen pollutants by using the microbial fuel cell realizes the cooperative control of the nitrogen removal process and the electron transmission process of the microbial fuel cell, improves the electron utilization efficiency and total nitrogen removal efficiency, reduces the accumulation of intermediate products, and enhances the system operation stability and long-term continuous nitrogen removal capacity.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for treating nitrogen pollutants using a microbial fuel cell. Background Technology

[0002] With the continuous increase in the discharge of industrial wastewater, domestic sewage, and aquaculture wastewater, the concentration of nitrogenous pollutants such as ammonia nitrogen, nitrate nitrogen, and nitrite nitrogen in wastewater is constantly rising. If nitrogenous pollutants are discharged directly into natural water bodies without effective treatment, they can easily cause environmental problems such as eutrophication and ecosystem imbalance. Therefore, developing efficient and stable denitrification technologies has always been an important research direction in the field of wastewater treatment.

[0003] Microbial fuel cells, as a novel bioelectrochemical technology integrating pollutant removal and biomass power generation, utilize electrons released during the decomposition of organic matter by electrogenic microorganisms to generate electrical energy, which then drives a reduction reaction at the cathode, achieving simultaneous wastewater purification and energy recovery. In recent years, microbial fuel cells have been increasingly applied in the treatment of nitrogen-containing wastewater, and the denitrification effect has been improved by adjusting operating parameters such as substrate concentration, dissolved oxygen, external load, and hydraulic retention time.

[0004] However, in actual operation, the denitrification performance of microbial fuel cells is affected by a variety of factors, including microbial activity, water quality changes, and operating conditions. The requirements for various operating parameters differ at different operating stages. When operating parameters change, it can easily lead to problems such as decreased denitrification efficiency, insufficient system stability, or fluctuations in power generation performance, making it difficult to maintain a stable and efficient denitrification effect in the long term. Summary of the Invention

[0005] The purpose of this invention is to provide a method for treating nitrogen pollutants using a microbial fuel cell, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides a method for treating nitrogen pollutants using a microbial fuel cell, comprising the following steps: S1. Establish a microbial fuel cell denitrification operation system and obtain initial operating parameters; S2. Establish a dynamic matching relationship between electron supply capacity and nitrogen pollutant conversion demand based on initial operating parameters; S3. Adjust the operating conditions of the microbial fuel cell based on the dynamic matching relationship and the conversion state of nitrogen pollutants; S4. Implement closed-loop control of the denitrification process based on operating conditions and electrochemical feedback information; S5. Determination of denitrification endpoint and system self-recovery operation based on closed-loop control process.

[0007] Preferably, S1 includes: S11. Construct a dual-chamber or single-chamber microbial fuel cell denitrification operation system, inoculate the anode chamber with electrogenic microbial flora, configure the cathode chamber with denitrification functional flora, and achieve synergistic transfer of electrons and ions between the two electrodes through a proton exchange membrane or isolation layer. S12. Detect the concentrations of ammonia nitrogen, nitrate, nitrite, COD, pH, conductivity, and dissolved oxygen in the wastewater to be treated, and simultaneously collect the open-circuit voltage, internal resistance, current density, and anodic oxidation-reduction potential of the microbial fuel cell to form an initial set of operating parameters. S13. Determine the start-up conditions of the microbial fuel cell based on the initial operating parameters, and set the anode organic substrate dosage concentration, cathode circulation flow rate, hydraulic residence time, and external load range.

[0008] Preferably, S2 includes: S21. During the stable operation of the microbial fuel cell, continuously monitor the anode electron release rate and the cathode electron consumption rate, and calculate the electron output capacity per unit time based on the change in anode current. S22. Based on the changes in the concentrations of ammonia nitrogen, nitrate, and nitrite in the wastewater, calculate the theoretical electron requirements for the removal of various nitrogen pollutants. S23. Compare the degree of matching between electron supply capacity and nitrogen pollutant conversion demand, so that the electron supply capacity is kept within a reasonable range to meet the denitrification reaction, and maintain stable power generation and continuous denitrification of the microbial fuel cell.

[0009] Preferably, comparing the matching degree between electron supply capacity and electron demand specifically involves: increasing the anode substrate supply rate or adjusting the external load to reduce internal resistance loss when electron supply is insufficient; and reducing the anode substrate concentration or increasing the cathode circulation rate when electron supply is excessive.

[0010] Preferably, S3 includes: S31. Based on the continuously detected ammonia nitrogen decrease rate, nitrate accumulation rate, nitrite accumulation rate, and output current changes, determine the current stage of the denitrification reaction. S32. When the ammonia nitrogen oxidation rate decreases, the dissolved oxygen concentration at the cathode and the circulation flow rate should be appropriately increased to enhance the nitrification process. S33. When nitrate or nitrite accumulation is detected, gradually reduce the dissolved oxygen at the cathode and increase the electron output at the anode to ensure that the denitrification process has sufficient electron donors. S34. Coordinate and adjust the wastewater influent flow rate, hydraulic retention time, and external load resistance to maintain a dynamic balance between the nitrification and denitrification processes, reduce the accumulation of intermediate products, and improve the total nitrogen removal efficiency.

[0011] Preferably, S4 includes: S41. Continuously collect the output voltage, current density, coulombic efficiency, polarization change rate and anode potential change of the microbial fuel cell, and construct a denitrification operation status evaluation index by combining the total nitrogen concentration change rate obtained by real-time detection. S42. Compare the calculated nitrogen removal operation status evaluation index with the preset evaluation threshold; S43. Based on the evaluation results, adjust the anode substrate loading acceleration rate, cathode aeration intensity, circulating pump flow rate and external resistor respectively to achieve dynamic coordination between electron transfer rate, biological metabolism rate and nitrogen pollutant removal rate. S44. If the evaluation index shows a downward trend in multiple consecutive sampling cycles, the influent load will be gradually reduced and the reaction residence time will be extended until the denitrification efficiency returns to stability, thus achieving closed-loop operation of the entire treatment process.

[0012] Preferably, the formula for calculating the denitrification operation status evaluation index is as follows: ; in, Total nitrogen removal rate; This is the normalized output voltage; This is the normalized output current density; , , This represents the corresponding weight coefficient, and .

[0013] Preferably, S42 is as follows: when When the value is greater than or equal to the preset evaluation threshold, the microbial fuel cell is determined to be in a stable denitrification operation state. when When the value is below a preset evaluation threshold, the denitrification performance of the microbial fuel cell is determined to have decreased, and based on... Adjust the anode substrate dosage, cathode aeration intensity, circulation flow rate, or external load according to the changes in the microbial fuel cell to restore it to a stable operating state.

[0014] Preferably, S5 includes: S51. Continuously monitor the concentrations of total nitrogen, ammonia nitrogen, nitrate, nitrite and COD in the treated water. When all indicators continuously meet the preset emission standards, the denitrification treatment is deemed complete. S52. Based on the current output curve, electron utilization rate, nitrogen removal rate and operating parameter change trajectory recorded during this round of operation, readjust the initial external load, anode substrate dosage and cathode circulation parameters for the next operating cycle, so that the microbial fuel cell can gradually recover to the optimal working state and enter the next batch of wastewater treatment cycle.

[0015] Therefore, the method for treating nitrogen pollutants using a microbial fuel cell described above has the following beneficial effects: (1) By establishing a dynamic matching relationship between electron supply capacity and nitrogen pollutant conversion demand, and dynamically adjusting the operating conditions based on the matching results, the present invention can keep the electron supply and denitrification demand of microbial fuel cells coordinated, improve electron utilization efficiency, avoid denitrification efficiency decline due to insufficient or excessive electron supply, and thus improve the operating stability of microbial fuel cells.

[0016] (2) The present invention determines the denitrification reaction stage based on the ammonia nitrogen decrease rate, nitrate accumulation rate, nitrite accumulation rate and output current change, and dynamically adjusts the cathode dissolved oxygen concentration, circulation flow rate, influent flow rate, hydraulic residence time and external load and other operating parameters in combination with the determination results, so as to achieve coordinated operation of nitrification and denitrification processes, which is conducive to reducing the accumulation of intermediate products in the denitrification process and improving the total nitrogen removal efficiency.

[0017] (3) The present invention constructs a denitrification operation status evaluation index, and performs closed-loop regulation of anode substrate dosage, cathode aeration intensity, circulation flow rate and external load based on the evaluation results, so that the operation status of microbial fuel cell can be monitored and dynamically adjusted in real time, realize the coordinated control of electron transfer process and denitrification process, and improve the stability of denitrification performance and power generation performance of microbial fuel cell.

[0018] (4) This invention optimizes and adjusts the operating parameters for the next operating cycle by determining the denitrification endpoint and the system self-recovery operation, so that the microbial fuel cell can quickly recover to a stable working state, reduce the frequency of manual intervention, improve the continuous operation capability of the system, and is suitable for long-term stable treatment of different nitrogen-containing wastewater.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a method for treating nitrogen pollutants using a microbial fuel cell, according to an embodiment of the present invention. Figure 2 This is a structural diagram of a microbial fuel cell according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of 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 scope of protection of the present invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] Example like Figure 1 As shown, the present invention provides a method for treating nitrogen pollutants using a microbial fuel cell, comprising the following steps: S1. Establish a microbial fuel cell denitrification operation system and obtain initial operating parameters.

[0024] In this embodiment, S1 includes: S11. Construct a dual-chamber or single-chamber microbial fuel cell denitrification operation system. The anode chamber is inoculated with electrogenic microbial flora, and the cathode chamber is configured with denitrification functional microbial flora. The two electrodes are connected via a proton exchange membrane or isolation layer to achieve coordinated electron and ion transfer. Figure 2 As shown.

[0025] S12. Detect the concentrations of ammonia nitrogen, nitrate, nitrite, COD, pH, conductivity, and dissolved oxygen in the wastewater to be treated, and simultaneously collect the open-circuit voltage, internal resistance, current density, and anodic oxidation-reduction potential of the microbial fuel cell to form an initial set of operating parameters.

[0026] S13. Determine the start-up conditions of the microbial fuel cell based on the initial operating parameters, and set the anode organic substrate dosage concentration, cathode circulation flow rate, hydraulic residence time and external load range to provide a unified operating basis for the subsequent denitrification process.

[0027] S2. Establish a dynamic matching relationship between electron supply capacity and nitrogen pollutant conversion demand based on initial operating parameters.

[0028] In this embodiment, S2 includes: S21. During the stable operation of the microbial fuel cell, continuously monitor the anode electron release rate and the cathode electron consumption rate, and calculate the electron output capacity per unit time based on the change in anode current.

[0029] In this embodiment, the anode electron release rate is not directly measured by the number of electrons, but is indirectly characterized by the current signal generated during the operation of the microbial fuel cell. Specifically, a current acquisition unit is set in the anode circuit to continuously acquire the output current at a fixed sampling period and simultaneously record the corresponding time information. Since the current essentially reflects the charge transfer rate through the conductor cross-section per unit time, and the electrons released during microbial metabolism ultimately form current through the external circuit, the total charge passing through the external circuit in each sampling period can be statistically calculated based on the continuously acquired current changes (i.e., the current value at each sampling moment is integrated over time to obtain the cumulative charge passing through the external circuit in the corresponding sampling period). Then, based on the correspondence between electrons and charge, the cumulative charge is converted into the number of electrons participating in the transfer in the corresponding time period, thereby obtaining the electron output capacity per unit time.

[0030] To reduce measurement errors caused by fluctuations in microbial metabolism and instantaneous load changes, a sliding time window is used to average the current data obtained in multiple consecutive sampling periods. Abnormal sampling values ​​exceeding a preset fluctuation threshold are removed, and the average trend of electron output capability within the continuous time period is calculated. Subsequently, the electron release is judged to be in a stable stage based on the anode potential change. When the change in electron output capability in multiple consecutive sampling periods is less than the preset fluctuation threshold, the average value of electron output capability in the corresponding time period is determined as the effective electron supply capability of the current microbial fuel cell.

[0031] The cathode electron consumption rate is indirectly characterized by the cathode circuit current and cathode potential changes. Since the electrons in the external circuit eventually flow into the cathode to participate in the reduction reaction, under stable operating conditions, the number of electrons received by the cathode per unit time corresponds to the number of electrons output by the anode per unit time. By combining the cathode potential change and the cathode reaction current, the actual cathode electron utilization rate can be determined, and the cathode electron consumption capacity can be evaluated accordingly.

[0032] S22. Based on the changes in the concentrations of ammonia nitrogen, nitrate, and nitrite in the wastewater, calculate the theoretical electron requirements for the removal of various nitrogen pollutants.

[0033] In this embodiment, the concentrations of ammonia nitrogen, nitrate nitrogen, and nitrite nitrogen in the wastewater are first continuously detected using a water quality detection unit installed at the inlet / outlet of the microbial fuel cell. Based on the change in the concentration of each pollutant between two adjacent sampling periods, the total amount of nitrogen elements to be converted corresponding to each type of nitrogen pollutant is calculated in conjunction with the treated water volume. Subsequently, based on the redox reaction pathways corresponding to different nitrogen-containing pollutants in the biological denitrification process, and in conjunction with the electron conservation relationship, the theoretical electron requirement corresponding to the completion of the target conversion of a unit of nitrogen element is determined, and this is used as the electron requirement standard for the corresponding pollutant.

[0034] Specifically, for ammonia nitrogen, the theoretical electron requirement for a unit of nitrogen element to complete the final removal is determined based on the overall electron transfer relationship during its conversion to nitrogen gas through nitrification and denitrification reactions. For nitrate nitrogen and nitrite nitrogen, the theoretical electron requirement for a unit of nitrogen element to complete the target conversion is determined based on the electron transfer process during their stepwise reduction to nitrogen gas in denitrification. Since different forms of nitrogen-containing pollutants are in different oxidation states, the number of electrons transferred for their final removal varies. Therefore, separate electron requirement standards are established for ammonia nitrogen, nitrate nitrogen, and nitrite nitrogen to accurately reflect the electron supply capacity requirements during the removal of different pollutants.

[0035] After obtaining the electron demand standards for various pollutants, the theoretical electron demand is calculated based on the actual total amount of nitrogen to be removed from each pollutant. The electron demands of each part are then summed to obtain the total electron demand required for the theoretical complete removal of nitrogen pollutants within the current treatment cycle. This theoretical electron demand characterizes the minimum electron demand required for the current pollutant to complete its target transformation, providing an evaluation benchmark for subsequent electron supply capacity matching, rather than representing actual electron consumption. The theoretical electron demand is then compared with the effective electron supply capacity obtained in step S21 to determine whether the current anode electron supply can meet the denitrification reaction requirements. When the electron supply capacity is lower than the theoretical electron demand, it is determined that the system has insufficient electron donors, and this determination is used as the basis for subsequent control measures such as increasing the anode substrate supply rate, adjusting the external load, or extending the hydraulic residence time. When the electron supply capacity is higher than the theoretical electron demand, it is determined that the system has an electron supply margin, and this margin is used as the basis for optimizing the external load, adjusting the influent load, or reducing the substrate dosage to improve electron utilization efficiency and reduce energy loss caused by electron redundancy.

[0036] S23. Compare the degree of matching between electron supply capacity and nitrogen pollutant conversion demand to ensure that electron supply capacity is always kept within a reasonable range to meet the denitrification reaction, thereby maintaining stable power generation and continuous denitrification of the microbial fuel cell.

[0037] In this embodiment, comparing the matching degree between electron supply capacity and electron demand specifically involves: when electron supply is insufficient, increasing the anode substrate supply rate or adjusting the external load to reduce internal resistance loss; when electron supply is excessive, reducing the anode substrate concentration or appropriately increasing the cathode circulation rate.

[0038] S3. Adjust the operating conditions of the microbial fuel cell based on the dynamic matching relationship and the conversion state of nitrogen pollutants.

[0039] In this embodiment, S3 includes: S31. Based on the continuously detected ammonia nitrogen decrease rate, nitrate accumulation rate, nitrite accumulation rate, and output current change, determine the current stage of the denitrification reaction.

[0040] S32. When the ammonia nitrogen oxidation rate decreases, the dissolved oxygen concentration at the cathode and the circulation flow rate should be appropriately increased to enhance the nitrification process.

[0041] S33. When nitrate or nitrite accumulation is detected, gradually reduce the dissolved oxygen at the cathode and increase the electron output at the anode to ensure sufficient electron donors for the denitrification process.

[0042] S34. Coordinate and adjust the wastewater influent flow rate, hydraulic retention time, and external load resistance to maintain a dynamic balance between the nitrification and denitrification processes, thereby reducing the accumulation of intermediate products and improving the total nitrogen removal efficiency.

[0043] S4. Implement closed-loop control of the denitrification process based on operating conditions and electrochemical feedback information.

[0044] In this embodiment, S4 includes: S41. Continuously collect the output voltage, current density, coulombic efficiency, polarization change rate and anode potential change of the microbial fuel cell, and construct a denitrification operation status evaluation index by combining the total nitrogen concentration change rate obtained by real-time detection.

[0045] In this embodiment, the output voltage, output current density, and total nitrogen concentration of the treated effluent from the microbial fuel cell are continuously collected. The total nitrogen removal rate is calculated based on the total nitrogen concentration, and a denitrification operation status evaluation index is constructed. This denitrification operation status evaluation index comprehensively reflects the denitrification capacity and power generation operation status of the microbial fuel cell, and its calculation formula is as follows: ; in, Total nitrogen removal rate; This is the normalized output voltage; This is the normalized output current density; , , This represents the corresponding weight coefficient, and .

[0046] Total nitrogen removal rate is used to characterize the removal efficiency of nitrogen pollutants, output voltage is used to characterize the electron transfer capability of the microbial fuel cell, and output current density is used to characterize microbial activity and system operational stability. By constructing a denitrification operating status evaluation index using these three parameters, both the denitrification performance and power generation performance of the microbial fuel cell can be simultaneously reflected.

[0047] After the microbial fuel cell was started up, the process performance parameters were obtained after 30 days of steady-state operation, as shown in Table 1.

[0048] Table 1. Process Performance Parameters

[0049] In terms of denitrification effect: After adopting the solution of this invention, the total nitrogen removal rate can reach 94.7%, the ammonia nitrogen removal rate is 98.3%, the effluent nitrite is only 0.7mg / L, the nitrification and denitrification reactions are in balance, the nitrogen removal is thorough, and the intermediate products accumulate very little.

[0050] At the electron matching level: the electron supply at the anode is slightly higher than the electron quantity required by the denitrification theory, which fully meets the electron demand of denitrification without causing electron redundancy and waste. The electron utilization efficiency is stable at 71.2%, and the electron resource utilization rate is high.

[0051] In terms of power generation performance: It can stably output voltage and current, with a coulombic efficiency of 60.8%, achieving simultaneous power generation and denitrification, and combining pollutant treatment and energy recovery effects.

[0052] In terms of operational stability: the evaluation index K reached 0.92, which is in the high stability range, indicating that the entire closed-loop control system can maintain efficient and stable operation in the long term.

[0053] S42. Compare the calculated denitrification operation status evaluation index with the preset evaluation threshold, specifically: when When the value is greater than or equal to a preset evaluation threshold, the microbial fuel cell is determined to be in a stable denitrification operation state; when... When the value is below a preset evaluation threshold, the denitrification performance of the microbial fuel cell is determined to have decreased, and based on... Adjust the anode substrate dosage, cathode aeration intensity, circulation flow rate, or external load according to the changes in the microbial fuel cell to restore it to a stable operating state.

[0054] S43. Based on the evaluation results, adjust the anode substrate loading acceleration rate, cathode aeration intensity, circulating pump flow rate, and external resistor respectively to achieve dynamic coordination between electron transfer rate, biological metabolism rate, and nitrogen pollutant removal rate.

[0055] S44. If the evaluation index shows a downward trend in multiple consecutive sampling cycles, the influent load will be gradually reduced and the reaction residence time will be extended until the denitrification efficiency returns to stability, thus achieving closed-loop operation of the entire treatment process.

[0056] S5. Determination of denitrification endpoint and system self-recovery operation based on closed-loop control process.

[0057] In this embodiment, S5 includes: S51. Continuously monitor the concentrations of total nitrogen, ammonia nitrogen, nitrate, nitrite, and COD in the treated effluent. Once all indicators continuously meet the preset emission standards, the denitrification treatment is deemed complete.

[0058] S52. Based on the current output curve, electron utilization rate, nitrogen removal rate and operating parameter change trajectory recorded during this round of operation, readjust the initial external load, anode substrate dosage and cathode circulation parameters for the next operating cycle, so that the microbial fuel cell can gradually recover to the optimal working state and enter the next batch of wastewater treatment cycle, so as to maintain long-term stable denitrification performance and power generation performance.

[0059] By deeply coupling the power generation process of microbial fuel cells with the biological denitrification process, the electron flow and nitrogen conversion are synchronously regulated, thereby improving the total nitrogen removal rate.

[0060] Therefore, the present invention adopts the above-mentioned method for treating nitrogen pollutants using a microbial fuel cell. By establishing a dynamic matching mechanism between electron supply capacity and theoretical electron demand of nitrogen pollutants, and by combining denitrification operation status evaluation indicators to perform closed-loop adjustment of operating parameters, the synergistic control of the denitrification process and electron transfer process of the microbial fuel cell is realized, which improves electron utilization efficiency and total nitrogen removal efficiency, reduces intermediate product accumulation, and enhances system operation stability and long-term continuous denitrification capability.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for treating nitrogen pollutants using a microbial fuel cell, characterized in that: Includes the following steps: S1. Establish a microbial fuel cell denitrification operation system and obtain initial operating parameters; S2. Establish a dynamic matching relationship between electron supply capacity and nitrogen pollutant conversion demand based on initial operating parameters, specifically including: S21. During the stable operation of the microbial fuel cell, continuously monitor the anode electron release rate and the cathode electron consumption rate, calculate the electron output capacity per unit time based on the anode current change, use a sliding time window to eliminate abnormal sampling values, and combine the anode potential change to determine the effective electron supply capacity of the anode. S22. Based on the changes in the concentrations of ammonia nitrogen, nitrate, and nitrite in the wastewater, calculate the theoretical electron requirements for the removal of various nitrogen pollutants. S23. Compare the degree of matching between electron supply capacity and nitrogen pollutant conversion demand, so that the electron supply capacity is kept within a reasonable range to meet the denitrification reaction, and maintain stable power generation and continuous denitrification of the microbial fuel cell. S3. Adjust the operating conditions of the microbial fuel cell based on the dynamic matching relationship and the conversion state of nitrogen pollutants; S4. Implement closed-loop control of the denitrification process based on operating conditions and electrochemical feedback information; S5. Determination of denitrification endpoint and system self-recovery operation based on closed-loop control process.

2. The method for treating nitrogen pollutants using a microbial fuel cell according to claim 1, characterized in that: S1 includes: S11. Construct a dual-chamber or single-chamber microbial fuel cell denitrification operation system, inoculate the anode chamber with electrogenic microbial flora, configure the cathode chamber with denitrification functional flora, and achieve synergistic transfer of electrons and ions between the two electrodes through a proton exchange membrane or isolation layer. S12. Detect the concentrations of ammonia nitrogen, nitrate, nitrite, COD, pH, conductivity, and dissolved oxygen in the wastewater to be treated, and simultaneously collect the open-circuit voltage, internal resistance, current density, and anodic oxidation-reduction potential of the microbial fuel cell to form an initial set of operating parameters. S13. Determine the start-up conditions of the microbial fuel cell based on the initial operating parameters, and set the anode organic substrate dosage concentration, cathode circulation flow rate, hydraulic residence time, and external load range.

3. The method for treating nitrogen pollutants using a microbial fuel cell according to claim 1, characterized in that: The comparison of the matching degree between electron supply capacity and electron demand is specifically as follows: when electron supply is insufficient, increase the anode substrate supply rate or adjust the external load to reduce internal resistance loss; when electron supply is excessive, reduce the anode substrate concentration or increase the cathode circulation rate.

4. The method for treating nitrogen pollutants using a microbial fuel cell according to claim 1, characterized in that: S3 includes: S31. Based on the continuously detected ammonia nitrogen decrease rate, nitrate accumulation rate, nitrite accumulation rate, and output current changes, determine the current stage of the denitrification reaction. S32. When the ammonia nitrogen oxidation rate decreases, the dissolved oxygen concentration at the cathode and the circulation flow rate should be appropriately increased to enhance the nitrification process. S33. When nitrate or nitrite accumulation is detected, gradually reduce the dissolved oxygen at the cathode and increase the electron output at the anode to ensure that the denitrification process has sufficient electron donors. S34. Coordinate and adjust the wastewater influent flow rate, hydraulic retention time, and external load resistance to maintain a dynamic balance between the nitrification and denitrification processes, reduce the accumulation of intermediate products, and improve the total nitrogen removal efficiency.

5. The method for treating nitrogen pollutants using a microbial fuel cell according to claim 1, characterized in that: S4 includes: S41. Continuously collect the output voltage, current density, coulombic efficiency, polarization change rate and anode potential change of the microbial fuel cell, and construct a denitrification operation status evaluation index by combining the total nitrogen concentration change rate obtained by real-time detection. S42. Compare the calculated denitrification operation status evaluation index with the preset evaluation threshold; S43. Based on the evaluation results, adjust the anode substrate loading acceleration rate, cathode aeration intensity, circulating pump flow rate and external resistor respectively to achieve dynamic coordination between electron transfer rate, biological metabolism rate and nitrogen pollutant removal rate. S44. If the evaluation index shows a downward trend in multiple consecutive sampling cycles, the influent load will be gradually reduced and the reaction residence time will be extended until the denitrification efficiency returns to stability, thus achieving closed-loop operation of the entire treatment process.

6. The method for treating nitrogen pollutants using a microbial fuel cell according to claim 5, characterized in that: The formula for calculating the evaluation index of denitrification operation status is as follows: K = a × η + b × U + c × I; Where η is the total nitrogen removal rate; U is the normalized output voltage; I is the normalized output current density; a, b, and c represent the corresponding weighting coefficients, and a+b+c=1.

7. The method for treating nitrogen pollutants using a microbial fuel cell according to claim 6, characterized in that: S42 specifically refers to: When K is greater than or equal to the preset evaluation threshold, the microbial fuel cell is determined to be in a stable denitrification operation state. When K is less than the preset evaluation threshold, it is determined that the denitrification performance of the microbial fuel cell has decreased. Based on the change of K, the anode substrate dosage, cathode aeration intensity, circulation flow rate or external load is adjusted to restore the microbial fuel cell to a stable operating state.

8. The method for treating nitrogen pollutants using a microbial fuel cell according to claim 1, characterized in that: S5 include: S51. Continuously monitor the concentrations of total nitrogen, ammonia nitrogen, nitrate, nitrite and COD in the treated effluent. When all indicators continuously meet the preset emission standards, the denitrification treatment is deemed complete. S52. Based on the current output curve, electron utilization rate, nitrogen removal rate and operating parameter change trajectory recorded during this round of operation, readjust the initial external load, anode substrate dosage and cathode circulation parameters for the next operating cycle, so that the microbial fuel cell can gradually recover to the optimal working state and enter the next batch of wastewater treatment cycle.

Images