An in-well electro-biological denitrification device, system and control method thereof

Abstract

The application relates to the technical field of groundwater in-situ remediation, in particular to an in-well electro-biological denitrification device, a system and a control method thereof. The device comprises: a device body arranged in a well, a water inlet arranged at the lower part of the side wall of the device body, and a water outlet arranged at the upper part of the device body; and a concentric electrode device arranged in the device body. The application separates and discharges oxygen produced by the positive electrode through a gas barrier discharge assembly to avoid denitrification inhibition, temporarily stores electric charges through conductive particulate fillers to match microbial metabolic rhythms and reduce electronic invalid dissipation, forces water flow through an internal circulation driving unit to improve mass transfer, and isolates the well section through an expansion sealing assembly to prevent water flow short circuiting. The whole device is designed as a cylindrical module which can be directly hung in a standard well, so that low-energy-consumption, anti-interference and high-efficiency in-situ groundwater denitrification deployment can be realized without civil construction.

Description

Technical Field

[0001] This invention relates to the field of in-situ groundwater remediation technology, and in particular to an in-well electrobiological denitrification device, system and control method thereof. Background Technology

[0002] In recent years, with the continuous increase in agricultural fertilization intensity and the increase in the discharge of livestock wastewater, the phenomenon of nitrogen infiltrating into groundwater aquifers through soil has become increasingly common, leading to a prominent problem of excessive nitrate nitrogen content in groundwater. Related medical research has confirmed that long-term intake of water with excessive nitrate levels can interfere with the normal oxygen-carrying function of human blood, posing a health risk, especially to infants and young children. Furthermore, nitrates are converted into nitrosamines in the human body, which are highly carcinogenic. Therefore, the World Health Organization and environmental agencies in many countries have set strict limits on nitrate nitrogen concentrations in drinking water. Against this backdrop, developing an in-situ purification technology that is easy to operate and maintain, energy-efficient, and produces no byproducts for rural areas with decentralized water supply and deep aquifers has become a critical issue that urgently needs to be addressed in the field of environmental engineering.

[0003] To address these challenges, the industry has developed various approaches to groundwater nitrate remediation, which can be broadly categorized into two systems: physicochemical methods and bioremediation. Among these, bioelectrochemical systems have received considerable attention in recent years. Their core technology lies in utilizing the electron transfer mechanism between microorganisms and electrodes to achieve pollutant transformation. Specifically, in an anaerobic environment, autotrophic denitrifying bacteria enriched on the cathode surface can directly acquire electrons from the electrode surface, or use hydrogen gas generated by electrode hydrolysis as an electron mediator, gradually reducing nitrate nitrogen to harmless nitrogen gas. The anode releases electrons through the electrolysis of water, forming a closed loop. Currently, the engineering implementation of this technology primarily relies on a continuous energization mode, applying a constant voltage or current to the electrode system via an external power source to maintain the reaction.

[0004] While the aforementioned methods have demonstrated feasibility in laboratory conditions or shallow groundwater remediation, their application in actual deep well environments faces multiple constraints. First, there is a significant asynchrony between continuous power input and microbial metabolic rhythms. When the electron supply rate exceeds the microbial utilization capacity, excess charge is dissipated through hydrogen evolution or heat generation, resulting in low energy efficiency. Second, existing reactor configurations rarely consider the negative impacts of anode oxygen production. Oxygen diffuses into the cathode region, disrupting the anaerobic environment, inhibiting denitrifying bacteria activity, and potentially triggering the generation and accumulation of the strong greenhouse gas nitrous oxide. Third, groundwater flow is extremely slow, making it difficult for traditional electrode structures to achieve effective contact between pollutants and biofilm within the limited space of the well casing; mass transfer efficiency becomes a bottleneck limiting overall treatment capacity. Furthermore, existing systems generally lack self-diagnosis and adjustment capabilities for operational status, failing to dynamically adjust operating modes based on changes in influent load. Long-term operation also leads to excessive biofilm proliferation or inorganic salt scaling, resulting in high maintenance costs and difficult replacement, hindering their widespread application in remote areas and deep well scenarios. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an in-well electrobiological denitrification device, system and control method thereof.

[0006] In a first aspect, embodiments of the present invention provide an in-well electrobiological denitrification device, the device comprising: The device body is located inside the well, with an inlet at the lower part of the side wall and an outlet at the upper part. A concentric electrode device is disposed within the main body of the device. The concentric electrode device includes a positive electrode unit located on the central axis, an annular negative electrode region arranged around the positive electrode unit, an ion-permeable isolation layer disposed between the positive electrode unit and the annular negative electrode region, and a reference potential sensor embedded inside the annular negative electrode region. The annular negative electrode region is filled with conductive microparticle filler, which is used to load electroactive microorganisms and form a charge storage medium. A gas barrier emission assembly is arranged around the outside of the positive electrode unit to physically isolate the gas generated at the positive electrode from the annular negative electrode region and guide it to the outside. The internal circulation drive unit, including a micro water pump and a diversion pipe, is used to force groundwater to flow from bottom to top within the annular negative pole region; The expansion sealing assembly includes an upper sealing bladder located on the top periphery of the device body and a lower sealing bladder located on the bottom periphery, for isolating the well section where the device is located from the external wellbore.

[0007] In conjunction with the first aspect, the gas barrier emission component is a porous insulating sleeve fitted outside the positive electrode unit, with the internal cavity of the porous insulating sleeve forming an exhaust channel communicating with the atmosphere; or, the gas barrier emission component is a hydrophobic and breathable membrane wrapped around the surface of the positive electrode unit.

[0008] In conjunction with the first aspect, the positive electrode unit is a hollow tubular structure, and its hollow portion constitutes an exhaust channel.

[0009] In conjunction with the first aspect, the annular negative electrode region also includes a conductive wire mesh current collector layer disposed close to the inner wall of the device body, and conductive microparticle filler filling the space between the conductive wire mesh current collector layer and the ion-permeable isolation layer; the conductive microparticle filler is pyrolytic biochar particles, or a mixture of pyrolytic biochar and zero-valent iron particles.

[0010] In addition to the first aspect, the top of the device body is also equipped with a load-bearing lifting ring and a waterproof cable interface.

[0011] Secondly, this application provides an in-well electrobiological denitrification system, comprising: Such as the in-well electrobiological denitrification device mentioned above; The control unit is electrically connected to the positive electrode unit, the annular negative electrode region, the reference potential sensor, and the internal circulation drive unit, respectively. The control unit is configured to alternately execute the pulse charging phase and the rest phase. During the rest phase, the control unit calculates the denitrification load in real time based on the open circuit potential and its decay slope monitored by the reference potential sensor and the pre-acquired Faraday pseudocapacitance value of the electroactive microorganisms, and accordingly adjusts the duration of the rest phase or the duty cycle of the power supply pulse.

[0012] Thirdly, this application provides a control method for an in-well electrobiological denitrification system, applied to the system described above; the method includes: During the pulse charging phase, electrons are injected into the annular negative electrode region to a set lower limit potential, and the Faraday pseudocapacitance value of the current electroactive microorganism is estimated based on the injected charge and potential difference. The power supply is cut off and the system enters a resting phase, continuously monitoring the open circuit potential at a preset sampling frequency. Calculate the potential decay slope based on the open-circuit potential; The real-time denitrification rate is calculated based on the product correlation model of Faraday pseudocapacitance and potential decay slope. Based on the comparison between the denitrification rate and the preset threshold, the duration of the current resting phase is adaptively adjusted. During the rest phase, if the real-time monitored open circuit potential drifts positively and touches the preset upper limit safety potential threshold, the current rest phase is forcibly terminated, and the system returns to the pulse charging phase.

[0013] In conjunction with the third aspect, the step of adaptively adjusting the duration of the current resting phase based on the comparison between the denitrification rate and a preset threshold includes: like If the condition is determined to be a high-load condition, the resting time is shortened or the resting period is ended early, and the pulse charging phase of step S1 is restarted. like and Within the preset benchmark range, it is determined to be a low-load operating condition, and the resting period is extended before it rises back to the upper limit safe potential threshold. like and If the value exceeds the preset baseline range, it is determined to be a loss of microbial activity, and a shutdown and alarm mode is executed. in, This represents the denitrification rate; The first threshold was obtained by pre-calibrating high-concentration polluted groundwater; This is the second threshold obtained by pre-calibrating the water quality to meet the standards; This is the system charge transfer resistance.

[0014] In conjunction with the third aspect, prior to the step of injecting electrons into the annular negative electrode region to a set lower limit potential during the pulse charging phase, and estimating the Faraday pseudocapacitance value of the currently electroactive microorganism based on the injected charge and potential difference, the method further includes: At the beginning of each control cycle, a high-frequency probe pulse lasting 100ms is applied to the concentric electrode device to collect the transient current response and calculate the solution resistance; Calculate the rate of change of resistance based on the solution resistance of adjacent periods; If the rate of change of resistance is higher than the preset threshold, it is determined that air accumulation or scaling has occurred in the packing gap, triggering the maintenance and regeneration mode. If the rate of change of resistance is lower than a preset threshold, the rate of change of resistance is considered stable.

[0015] In conjunction with the third aspect, after the steps to trigger the maintenance and regeneration mode, the following are also included: By using a polarity switching circuit, the positive pole unit of the central axis is temporarily switched to connect to the negative pole of the power supply, and the annular negative pole region is temporarily switched to connect to the positive pole of the power supply. Running at a preset high current for a preset time, the acidic environment generated in the annular negative electrode region dissolves inorganic carbonate scale, and the shearing force of the generated microbubbles peels off the aged electroactive microbial membrane. After cleaning, the electrode polarity is restored and the normal pulse control cycle is restarted.

[0016] The embodiments of the present invention bring the following beneficial effects: This application provides an in-well electrobiological denitrification device, system, and control method. The device includes: a device body disposed within a well, with an inlet at the lower part of the side wall and an outlet at the upper part; a concentric electrode device disposed within the device body; the concentric electrode device includes a positive electrode unit located on the central axis, an annular negative electrode region arranged around the positive electrode unit, an ion-permeable isolation layer disposed between the positive electrode unit and the annular negative electrode region, and a reference potential sensor embedded inside the annular negative electrode region; wherein, the annular... The annular negative electrode region is filled with conductive microparticle filler, which is used to load electroactive microorganisms and form a charge storage medium; a gas barrier emission component is arranged around the outside of the positive electrode unit to physically isolate the gas generated by the positive electrode from the annular negative electrode region and guide it to the outside; an internal circulation drive unit, including a micro water pump and a diversion pipe, is used to force groundwater to flow from bottom to top in the annular negative electrode region; an expansion sealing component, including an upper sealing bladder located on the top periphery of the device body and a lower sealing bladder located on the bottom periphery, is used to isolate the well section where the device is located from the external well casing.

[0017] This application uses a gas barrier emission component to isolate and discharge the positive electrode oxygen production to avoid denitrification inhibition, uses conductive microparticle packing to temporarily store charge to match the metabolic rhythm of microorganisms and reduce ineffective electron dissipation, uses an internal circulation drive unit to force water flow to improve mass transfer, uses an expansion sealing component to isolate the well section to prevent water flow short circuits, and is designed as a cylindrical module that can be directly suspended in a standard well. Thus, it can achieve low-energy consumption, anti-interference, and high-efficiency in-situ groundwater denitrification deployment without the need for civil construction.

[0018] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the in-well electrobiological denitrification device provided in an embodiment of the present invention; Figure 2 A schematic diagram of the cross-sectional structure of the in-well electrobiological denitrification device provided in an embodiment of the present invention at A-A'; Figure 3 A schematic flowchart illustrating the control method of the in-well electrobiological denitrification system provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the control unit provided in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To facilitate understanding of this embodiment, the technical terms used in this application will be briefly introduced below.

[0024] Electroactive biomembranes are microbial aggregates that attach to the surface of conductive fillers and can directly exchange electrons with electrodes. Their outer cell membranes are rich in conductive proteins such as cytochrome c, and they have the ability to store and release electrons.

[0025] Faraday pseudocapacitance: The charge storage characteristics of electroactive biomembranes due to reversible redox reactions (such as the valence state change of heme cofactors in extracellular proteins) enable biomembranes to absorb electrons during the charging phase and release electrons during the discharging phase, exhibiting capacitor-like behavior.

[0026] Open circuit potential (OCP): The potential that the working electrode (such as the cathode) naturally establishes relative to the reference potential sensor after the external power supply is cut off. Its magnitude is related to the amount of charge stored in the biofilm and the state of the interfacial reaction.

[0027] After introducing the technical terms used in this application, the application scenarios and design concepts of the embodiments of this application will be briefly described below.

[0028] Among existing in-situ groundwater nitrate remediation technologies, physicochemical methods (such as extraction and permeable reactive barriers) are costly and have construction limitations; in-situ bioremediation is prone to blockage or secondary pollution due to improper carbon source addition. Although bioelectrochemical systems have potential, they still suffer from shortcomings such as energy waste caused by the asynchrony between continuous power supply and microbial metabolic rhythms, anode oxygen production damaging the cathode anaerobic environment and causing greenhouse gas accumulation, low mass transfer efficiency in deep well environments, reactor structure incompatible with standard well pipes, and lack of self-diagnosis and self-cleaning capabilities, which restrict their widespread application in deep wells and remote areas.

[0029] Based on this, this application provides an in-well electrobiological denitrification device, system, and control method.

[0030] Example 1 This application provides an in-well electrobiological denitrification device, combined with... Figure 1 , Figure 2 As shown, the device includes: a device body, a concentric electrode device, a gas barrier emission assembly, an internal circulation drive unit, and an expansion sealing assembly.

[0031] The device body 100 is located inside the well. The lower part of the side wall of the device body 100 is provided with a water inlet 101 and the upper part is provided with a water outlet 102.

[0032] A concentric electrode device is disposed within the device body 100. The concentric electrode device includes a positive electrode unit 200 located on the central axis, an annular negative electrode region 400 arranged around the positive electrode unit 200, an ion-permeable isolation layer 300 disposed between the positive electrode unit 200 and the annular negative electrode region 400, and a reference potential sensor 700 embedded inside the annular negative electrode region 400. The annular negative electrode region 400 is filled with conductive microparticle filler 420, which is used to load electroactive microorganisms and form a charge storage medium.

[0033] A gas barrier emission assembly is arranged around the outside of the positive electrode unit to physically isolate the gas generated at the positive electrode from the annular negative electrode region 400 and guide it to the outside.

[0034] The internal circulation drive unit includes a micro water pump 500 and a guide pipe 510, which is used to force groundwater to flow from bottom to top within the annular negative pole region 400.

[0035] The expansion sealing assembly includes an upper sealing bladder 110 located on the top periphery of the device body 100 and a lower sealing bladder 120 located on the bottom periphery, for isolating the well section where the device is located from the external wellbore.

[0036] The in-well electrobiological denitrification device provided by this invention has the following beneficial effects: By filling the annular negative electrode region 400 in the concentric electrode device with conductive microparticle packing 420, a three-dimensional particle electrode and charge storage medium are formed, achieving dynamic matching between electron supply and microbial metabolic rhythm, significantly improving coulombic efficiency; The gas barrier emission component physically isolates and guides the oxygen generated at the anode to the outside, effectively maintaining a strictly anaerobic environment in the cathode region, avoiding suppression of denitrifying bacteria activity and preventing the generation of the strong greenhouse gas nitrous oxide, thus ensuring the safety of the effluent; The internal circulation-driven single... The forced flow of groundwater within the annular negative electrode region 400 overcomes the mass transfer bottleneck caused by slow natural flow velocity, thereby improving the treatment capacity per unit volume. An expansion sealing assembly isolates the well section containing the device from the external well casing, preventing short-circuiting of the water flow and ensuring that all contaminated water flows out through the treatment area, thus improving the reliability of in-situ remediation. Furthermore, a reference potential sensor 700, buried within the annular negative electrode region 400, in conjunction with pulse control, enables the system to adaptively adjust its operating mode according to the contaminant load and possesses health diagnostics and polarity reversal self-cleaning functions, effectively reducing maintenance costs.

[0037] In this embodiment, the device body 100 is a cylindrical shell with a water inlet 101 on the lower part of the side wall and a water outlet 102 on the upper part. The whole can be lowered into an underground water well to serve as the mounting base for each functional component.

[0038] The concentric electrode device is located inside the device body 100 and adopts a coaxial layout. The central axis is the positive electrode unit 200 (anode); the annular negative electrode region 400 (cathode region) surrounding it is filled with conductive microparticle filler 420 (such as biochar). This filler can both support electroactive microorganisms to form a biofilm and has charge storage capability due to its Faraday pseudocapacitance properties; an ion-permeable isolation layer 300 (such as hydrophilic nylon mesh) is set between the positive electrode unit 200 and the annular negative electrode region 400 to allow ion migration but block air bubbles; a reference potential sensor 700 (such as Ag / AgCl reference potential sensor) is also embedded in the annular negative electrode region 400 for real-time monitoring of the cathode potential.

[0039] The gas barrier emission assembly is arranged around the outside of the positive electrode unit 200. Its function is to physically confine the oxygen (O2) generated by the electrolysis of water in the anode area and guide it to the outside atmosphere through independent channels (such as gas guide pipe, hydrophobic and breathable membrane or hollow anode structure), preventing oxygen from diffusing laterally into the annular negative electrode area 400, thereby protecting the strict anaerobic environment of the cathode area.

[0040] The internal circulation drive unit consists of a micro water pump 500 and a guide pipe 510. The inlet of the micro water pump 500 is connected to the inlet 101 at the bottom of the device body 100, and the outlet is connected to the bottom of the annular negative electrode region 400 through the guide pipe 510. During operation, groundwater is forced to flow from bottom to top through the annular negative electrode region 400, forming a directional flow to overcome the problem of limited mass transfer caused by the slow flow rate of natural groundwater.

[0041] The expansion sealing assembly includes an upper sealing bladder 110 located on the top periphery of the device body 100 and a lower sealing bladder 120 located on the bottom periphery (i.e., upper and lower packers). After the device is lowered to a predetermined depth, the sealing bladder is pressed tightly against the well wall by inflation or mechanical expansion, isolating the well section where the inlet 101 and outlet 102 are located from the external well casing. This forces all groundwater to enter the device through the inlet 101, flow through the annular negative electrode area 400 for treatment, and then discharge from the outlet 102, preventing short circuits in the water flow.

[0042] In practical applications, after the device is lowered into the target aquifer section of the groundwater well, the upper sealing bladder 110 and the lower sealing bladder 120 are expanded to fit tightly against the well wall, thereby completely isolating the well section containing the inlet 101 and outlet 102 from the external well casing and preventing short-circuiting of the water flow. At this time, under the hydraulic gradient of the groundwater or the suction effect of the internal water pump, the groundwater can only enter from the inlet 101 at the bottom of the device body 100. The micro water pump 500 in the internal circulation drive unit is started, and the incoming groundwater is forcibly pumped from bottom to top into the annular negative electrode region 400 of the concentric electrode device through the guide pipe 510, so that the water flow is in a plug flow or fluidized state, which improves the mass transfer rate of pollutants to the electrode surface and biofilm, and alleviates the mass transfer bottleneck caused by the slow natural flow rate (cm / day).

[0043] Within the annular negative electrode region 400, an electroactive autotrophic denitrification biofilm is enriched on the surface of the conductive microparticle packing 420 (such as biochar). This biofilm possesses Faraday pseudocapacitance properties, enabling it to reversibly store and release electrons. The control unit 600 employs a pulsed power supply strategy: first, a charging pulse is applied between the positive electrode unit 200 and the annular negative electrode region 400, injecting electrons into the biofilm and conductive microparticle packing 420 until the cathode potential reaches a set lower limit (e.g., -0.6V). At this point, the electron carriers (such as cytochrome c) and conductive matrix within the biofilm reach electron saturation. Subsequently, the external power supply is cut off, and the system enters an open-circuit rest phase. The biofilm utilizes its stored electrons to drive the denitrification reaction, releasing nitrate (NO3) into the oxygen supply. - The gas is gradually reduced to harmless nitrogen (N2). During the rest period, a reference potential sensor 700 embedded in the annular negative electrode region 400 monitors the cathode open circuit potential in real time at a high frequency (e.g., >10Hz), and the control unit 600 calculates the potential decay slope. Based on the kinetic relationship between denitrification rate and potential slope, the system can dynamically deduce the influent nitrate load: a large slope indicates high pollutant concentration and rapid electron consumption, and the control unit automatically shortens the rest time or ends the rest period early, re-entering the charging phase to achieve rapid response under high load; a small slope indicates that pollutants have been largely removed, and the system significantly extends the rest time, entering a deep energy-saving mode. Simultaneously, to prevent electron depletion from inactivating nitrous oxide reductase and generating the strong greenhouse gas N2O, the system sets a potential safety threshold (e.g., -0.2V). Once the potential rises to this threshold, regardless of the slope, charging is forcibly initiated to ensure the reaction endpoint is harmless N2.

[0044] During the aforementioned charging and resting cycle, the central positive electrode unit 200 undergoes an oxygen evolution reaction (2H₂O → O₂ + 4H₂O). + +4e - The gas barrier and emission components surrounding the positive electrode unit 200 (such as gas guide pipes, hydrophobic and permeable membranes, or hollow anode structures) physically confine the generated oxygen within the anode region and discharge it vertically upwards through independent exhaust channels to the wellhead. This completely prevents oxygen diffusion into the annular negative electrode region 400, maintaining a strictly anaerobic environment in the cathode region and preventing the suppression of denitrifying bacteria activity and N2O generation. The ion-permeable isolation layer 300 allows protons (H2O) to pass through. + The isoelectric charge carriers pass through a closed circuit while blocking microbubbles, further ensuring the gas-liquid separation effect.

[0045] When the system has been running for a certain period of time or when the reference potential sensor 700, in conjunction with the impedance diagnostic pulse, detects an abnormal increase in resistance in the packing gaps due to scaling of inorganic salts such as calcium carbonate, the control unit 600 initiates a polarity reversal self-cleaning program: switching the central positive electrode unit 200 to the negative electrode and the annular negative electrode region 400 to the positive electrode, and running at a high current 2 to 5 times higher than the normal operating current for several minutes. At this time, an oxidation reaction occurs on the surface of the conductive particle packing 420, generating a large amount of H2O. + The local pH value rapidly drops below 4, dissolving inorganic scale. Simultaneously, the physical shear force of microbubbles peels away aged biofilm. After cleaning, the polarity is restored, and the system resumes normal denitrification circulation. The expansion sealing component ensures the airtightness of the hydraulic path throughout the process, and the internal circulation drive unit continuously provides forced convection, enabling this invention to achieve efficient, energy-saving, safe, and low-maintenance in-situ remediation of groundwater nitrates in deep well environments.

[0046] Example 2 Based on the aforementioned in-well electrobiological denitrification device, the gas barrier emission component specifically employs a porous insulating sleeve (such as a porous polypropylene pipe or UPVC pipe). This sleeve is coaxially fitted around the outside of the positive electrode unit 200 (central anode), and its wall has multiple micropores or slits (the pore size is designed to allow gas passage while using surface tension to prevent large-scale liquid water infiltration). The internal cavity of the sleeve extends upwards and directly communicates with the outside atmosphere, forming an independent exhaust channel 220. The positive electrode unit 200 (such as a titanium-based mixed metal oxide tubular electrode) is completely enclosed within this porous insulating sleeve, with a gap or direct contact between the two to ensure gas can enter the sleeve's interior. An ion-permeable isolation layer 300 (such as a hydrophilic nylon mesh) is positioned between the outer side of the porous insulating sleeve and the annular negative electrode region 400.

[0047] In this way, the micropores on the wall of the porous insulating bushing allow oxygen bubbles generated by the electrolysis of water at the anolyte to pass through and enter the internal cavity of the bushing. However, due to the hydrophobicity of the bushing material or the capillary pressure of the micropores, liquid water is blocked outside the bushing, thus achieving a gas-liquid separation effect that is "permeable to air but impermeable to water". The upper end of the internal cavity of the bushing is open to the top of the device body 100 or communicates with the wellhead atmosphere through a channel in the sealed chamber, so that oxygen rises vertically along the internal cavity of the bushing under the action of buoyancy and is discharged outside the well, preventing oxygen from diffusing laterally into the annular negative electrode region 400.

[0048] In practical applications, after the device is lowered into the well and the expansion sealing components (upper sealing bladder 110, lower sealing bladder 120) are set, groundwater enters the device through the inlet 101 and is forced to flow upward through the annular negative electrode region 400 by the internal circulation drive unit (micro water pump 500 + guide pipe 510). In the concentric electrode device, the control unit 600 applies pulsed electrical energy to the positive electrode unit 200 and the annular negative electrode region 400. An oxygen evolution reaction occurs on the surface of the positive electrode unit 200, generating a large number of fine oxygen bubbles. At this time, because the porous insulating sleeve is tightly fitted outside the positive electrode unit 200, these oxygen bubbles cannot pass through the sleeve wall to enter the outer annular negative electrode region 400. The bubbles first enter the internal cavity of the sleeve through the micropores on the sleeve wall (the micropore size is designed so that bubbles can enter, but liquid water is blocked due to surface tension), and then move vertically upward along the internal cavity of the sleeve under the drive of buoyancy, and finally are discharged into the upper space of the well or directly connected to the atmosphere from the exhaust port at the top of the device. This process achieves physical and complete isolation between oxygen and the cathode area.

[0049] At the same time, the ion-permeable isolation layer 300 on the outside of the sleeve allows protons (H) generated by the anodic reaction to pass through. +Other ions pass through to maintain circuit closure and charge balance, but further block any microbubbles that may escape. The electroactive biofilm, supported by conductive microparticle filler 420 (such as biochar) within the annular negative electrode region 400, receives and stores electrons during the charging phase of pulsed power supply, and uses the stored electrons to reduce nitrates to nitrogen gas during the resting phase. A reference potential sensor 700, embedded within the annular negative electrode region 400, monitors the cathode potential in real time, and, in conjunction with the control algorithm of the control unit 600, achieves on-demand power supply, adaptive adjustment, and potential safety threshold protection (preventing N2O accumulation). When the system detects scaling or biofilm aging, it can also initiate a polarity reversal self-cleaning program, utilizing the generated H₂O... + In-situ cleaning with microbubbles.

[0050] Throughout the process, the porous insulating sleeve, acting as a gas barrier emission component, works in synergy with the expansion sealing component (upper sealing bladder 110, lower sealing bladder 120, ensuring water flow path), the internal circulation drive unit (micro water pump 500, guide pipe 510, enhancing mass transfer), and the concentric electrode device (positive electrode unit 200, annular negative electrode region 400, ion-permeable isolation layer 300, conductive microparticle filler 420, reference potential sensor 700, electronic storage and utilization). This enables the device to simultaneously achieve efficient mass transfer, strict anaerobic environment maintenance, pulsed energy-saving power supply, and maintenance-free operation within the narrow space of a deep well, thereby significantly improving the in-situ remediation effect of groundwater nitrate pollution.

[0051] Example 3 Compared with Embodiments 1 and 2, the difference in this embodiment is that the gas barrier emission component is a hydrophobic and breathable membrane wrapped around the surface of the positive electrode unit 200.

[0052] Specifically, a hydrophobic microporous membrane made of polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) is tightly wrapped around the outer surface of the central positive electrode unit 200 (such as a titanium-based mixed metal oxide tubular electrode) by heat sealing or winding. The pore size of this hydrophobic and breathable membrane is between 0.1 μm and 0.5 μm, which has excellent air permeability and water resistance. It allows oxygen molecules generated by anolyte electrolysis of water to escape through the membrane pores, while effectively blocking the penetration of liquid water and air bubbles by utilizing the hydrophobic surface tension of the membrane, thereby forming a "breathable and water-resistant" gas-liquid separation interface on the surface of the positive electrode unit 200.

[0053] During charge-discharge cycles, oxygen is generated on the surface of the positive electrode unit 200 through an oxygen evolution reaction. Due to the tight encapsulation of the hydrophobic and permeable membrane, oxygen molecules escape outwards in gaseous form through the membrane pores, but liquid water and ionic solutions outside the membrane cannot permeate in the reverse direction. The escaped trace amounts of oxygen move upwards along the narrow gap between the ion-permeable isolation layer 300 and the hydrophobic and permeable membrane under buoyancy, and are discharged into the wellhead atmosphere through the exhaust channel 220 at the top of the device, effectively preventing oxygen from entering the annular negative electrode region 400 and disrupting the anaerobic environment. Compared to the porous insulating sleeve used in Example 1, the hydrophobic and permeable membrane structure in this embodiment is more compact and occupies less space, making it particularly suitable for deep well scenarios with limited diameter (such as DN75 well casing) or strict limitations on device length.

[0054] The system also features an in-situ self-cleaning function: when the system has accumulated 48 hours of operation or when an abnormal increase in packing resistance is detected, the control unit 600 initiates a polarity reversal program, operating at a high current of 50mA / cm² for 5-10 minutes to dissolve calcium carbonate scale and remove aged biofilm using localized acid production. After cleaning, the polarity is reset, restoring normal denitrification circulation.

[0055] In conjunction with the first aspect, the positive electrode unit is a hollow tubular structure, and its hollow portion constitutes an exhaust channel.

[0056] Specifically, the anode electrode 210 (such as a titanium-based mixed metal oxide (Ti-MMO) tube) is constructed as a hollow tube or placed inside a porous insulating gas-conducting tube, thus forming a vertically penetrating exhaust path at the geometric center of the device. During the electrochemical reaction, an oxygen evolution reaction occurs on the surface of the anode electrode 210, and the generated oxygen bubbles rise naturally due to buoyancy. By making the anode electrode 210 a hollow tube, these bubbles are physically confined within the central channel, preventing them from diffusing laterally to the outer annular negative electrode region 400. Simultaneously, the top of this exhaust channel 220 directly connects to the wellhead atmosphere, allowing oxygen to be efficiently and directionally discharged vertically without accumulating inside the device or interfering with the anaerobic conditions of the cathode region. This design achieves gas-liquid separation without additional power, effectively preventing the inhibition of denitrifying bacteria by oxygen, ensuring the thoroughness of the denitrification reaction, and avoiding the accumulation of the strong greenhouse gas nitrous oxide. Therefore, the hollow tubular structure is not only a conductive support for the anode but also an exhaust component integrating gas-liquid separation function to achieve efficient and stable in-situ remediation.

[0057] In conjunction with the first aspect, the annular negative electrode region 400 also includes a conductive wire mesh current collector layer 410 disposed close to the inner wall of the device body 100, and a conductive particle filler 420 filling the space between the conductive wire mesh current collector layer 410 and the ion-permeable isolation layer 300.

[0058] A conductive wire mesh current collector layer 410 is disposed close to the inner wall of the device body 100 (cylindrical outer shell). This current collector layer 410 is typically made of stainless steel (SS316L) wire mesh and is electrically connected to the negative terminal of the power supply, serving as a framework for current collection and distribution. The annular space between the current collector layer 410 and the central ion-permeable isolation layer 300 is filled with conductive microparticle filler 420. This design expands the traditional two-dimensional planar cathode into a three-dimensional particle electrode bed: the current collector layer 410 ensures that the electric field can be uniformly applied across the entire annular cross-section, while the filled conductive microparticle filler 420 contacts each other and conducts through the current collector layer 410, allowing the electric field to extend inward from the current collector layer 410 to the surface of the ion-permeable isolation layer 300, eliminating the electric field dead zone within the annular region. Simultaneously, the conductive microparticle filler 420 provides a large specific surface area for the electroactive biofilm and can serve as a charge storage medium. During operation, groundwater flows from bottom to top through the three-dimensional packing bed, and pollutants come into full contact with denitrifying bacteria attached to the surface of the conductive particulate packing 420, thereby significantly improving the reactor's volume utilization efficiency and mass transfer performance.

[0059] In conjunction with the first aspect, the conductive microparticle filler 420 is pyrolytic biochar particles, or a mixture of pyrolytic biochar and zero-valent iron particles.

[0060] Pure pyrolytic biochar possesses a high specific surface area (typically greater than 300 m² / g), good conductivity, and adsorption capacity. It serves as an ideal attachment carrier for electroactive denitrifying biofilms and, due to its Faraday pseudocapacitive properties, can store electrons, acting as an energy buffer. In scenarios requiring enhanced resistance to high nitrate loads, the conductive particulate packing 420 can utilize a mixture of biochar and zero-valent iron (ZVI), with a mass ratio ranging from 1:1 to 15:1, preferably 5:1 to 10:1. The addition of ZVI provides an auxiliary chemical reduction pathway: when the influent pollutant concentration suddenly increases and the biological reduction rate is temporarily insufficient, ZVI can directly chemically reduce nitrates or generate hydrogen (H₂) through corrosion for use by autotrophic denitrifying bacteria, thereby significantly improving the system's tolerance to shock loads. Simultaneously, the micro-coupler effect formed by ZVI and biochar also helps maintain the electron transfer efficiency of the packing bed.

[0061] In conjunction with the first aspect, the top of the device body 100 is also equipped with a load-bearing lifting ring 130 and a waterproof cable interface 140.

[0062] Understandably, the load-bearing lifting ring 130 is made of stainless steel and is used to connect the downhole cable or wire rope, allowing the entire cylindrical module to be safely and vertically suspended at a predetermined depth within a standard groundwater monitoring well or water supply well (such as a DN100 / 4-inch well pipe), and to withstand the weight of the device itself and the tensile force after the packer expands. During installation, the entire device is lowered vertically to the predetermined depth within the groundwater monitoring well or water supply well (usually corresponding to the aquifer screen section) by connecting the load-bearing lifting ring 130 with a wire rope or cable. After the device is in place, the packer assembly (upper sealing bladder 110, lower sealing bladder 120) is inflated or mechanically expanded to inflate and press tightly against the well wall, thereby isolating the well section where the device is located vertically and forcing groundwater flow to pass through the device's interior. Finally, the ground power supply and control system are connected via the waterproof cable interface 140 to start operation. This installation process requires no additional civil engineering work, enabling rapid and reliable deployment of the in-situ repair module.

[0063] The waterproof cable interface 140 is used to introduce ground power, control signals and sensor data lines into the sealed compartment at the top of the device; this interface has a high waterproof and dustproof rating (such as IP68) and can withstand long-term immersion in the well environment, ensuring reliable power supply and bidirectional communication for electrical components such as the control unit 600, reference potential sensor 700, and micro water pump 500.

[0064] The reasonable layout of the load-bearing lifting ring 130 and the waterproof cable interface 140 enables the device to be deployed quickly in a "plug and play" manner without the need for additional civil construction, which greatly reduces the difficulty of on-site installation and subsequent lifting and maintenance.

[0065] Example 4 The in-well electrobiological denitrification device provided in this embodiment is suitable for rural single-well remediation scenarios where the effluent water quality requirements are extremely high (it needs to meet the drinking water standard of nitrate nitrogen <10mg / L).

[0066] In this embodiment, the in-well electrobiological denitrification device is cylindrical in shape, with a diameter of 95 mm (suitable for DN100 well casing) and a length of 1500 mm. The device body 100 is made of food-grade UPVC material, and is equipped with inflatable rubber packers (upper sealing bladder 110 and lower sealing bladder 120) at the top and bottom. The positive electrode unit 200 is a 10 mm diameter titanium tube coated with an IrO2-Ta2O5 coating. The anode is placed inside a 20 mm diameter porous polypropylene tube as an exhaust channel 220. The ion-permeable isolation layer 300 is a hydrophilic nylon mesh (300 mesh) wrapped around the exhaust channel. The annular negative electrode region 400 is filled with 3-5 mm high-temperature pyrolytic biochar (i.e., conductive microparticle filler 420) in the annular space between the ion-permeable isolation layer 300 and the device body 100. The reference potential sensor 700 is a solid Ag / AgCl reference potential sensor embedded in the center of the cathode bed. The bottom integrates a 12V DC micro water pump 500, with a flow rate set to 20L / h, so that the hydraulic residence time in the device is about 2 hours.

[0067] In this embodiment, the in-well electrobiological denitrification device employs MB-PPMC control based on slope prediction, with the control unit 600 sampling at a frequency of 10 Hz. Under continuous flow conditions, a constant potential of -0.5V (vsAg / AgCl) is applied for 14 days until the biofilm matures.

[0068] Under normal operating conditions, the power supply first injects electrons into the annular negative electrode region 400 in constant current mode until the cathode potential reaches -0.6V, then switches to constant voltage maintenance until the charging current decays to below 5mA. Subsequently, a predictive pause program is executed, and the control unit 600 calculates the open-circuit potential decay slope S in real time. When S > 1.0 mV / s, a high load is identified, the pause is shortened, and the duty cycle is increased to 70%; when S < 0.1 mV / s and the charge transfer resistance is... When the voltage is <50Ω, it is considered a low load, and the duty cycle is reduced to 5%–10%; regardless of the duration of the rest, once the potential shifts positively to -0.2V, forced charging is initiated; however, when S is extremely small... When the voltage rises abnormally (>200Ω), it is determined that the microbial activity has been lost (such as poisoning or scaling that obstructs electron transfer). The power supply will be immediately cut off and an alarm signal will be output to prompt manual maintenance.

[0069] Treatment effect: With influent nitrate concentration fluctuating between 20-100 mg / L, effluent nitrate concentration is stable at <5 mg / L, saving 55% energy compared to the traditional constant pressure mode.

[0070] Example 5 The in-well electrobiological denitrification device provided in this embodiment is suitable for remediation scenarios in heavily polluted agricultural areas with high-hardness groundwater and high-concentration pollution (nitrate nitrogen > 80 mg / L), emphasizing the system's robustness and maintenance-free capability.

[0071] In this embodiment, the in-well electrobiological denitrification device is cylindrical in shape, with a diameter of 95 mm (suitable for DN100 well casing) and a length of 1500 mm. The device body 100 is made of UPVC material, and is equipped with inflatable rubber packers (upper sealing bladder 110 and lower sealing bladder 120) at the upper and lower ends. The positive electrode unit 200 is a 10 mm diameter boron-doped diamond (BDD) electrode, which has stronger oxidation capacity and durability. The anode is placed in a 20 mm diameter porous polypropylene tube as an exhaust channel 220. The ion-permeable isolation layer 300 is a hydrophilic nylon mesh (300 mesh) wrapped around the exhaust channel. The annular negative electrode region 400 is a composite filler filling the annular space between the ion-permeable isolation layer 300 and the device body 100. This composite filler is made of high-temperature pyrolytic biochar and zero-valent iron (ZVI) particles mixed at a mass ratio of 5:1 (i.e., conductive microparticle filler 420), with a particle size of 3-5 mm. The reference potential sensor 700 is a solid-state Ag / AgCl reference potential sensor embedded in the center of the cathode bed. A 12V DC micro water pump 500 is integrated at the bottom, with a flow rate set to 30L / h, ensuring a hydraulic residence time of approximately 1.5 hours within the device.

[0072] In this embodiment, the in-well electrobiological denitrification device employs a dual-threshold hysteresis control strategy. Under continuous flow conditions, a constant potential of -0.5V (vsAg / AgCl) is applied for 14 days until the biofilm matures.

[0073] Under normal operating conditions, the power supply first injects electrons into the annular negative electrode region 400 in constant current mode until the cathode potential reaches -0.65V. Then, it switches to constant voltage maintenance until the charging current decays to below 5mA. Subsequently, a rest procedure is executed, and the power supply is disconnected. Because the chemical corrosion of zero-valent iron in the composite filler can provide additional electrons, the rest period is usually relatively long. When the open-circuit potential naturally drifts back to -0.25V, recharging is triggered, forming a hysteresis loop of charging to -0.65V → rest → rising back to -0.25V triggering recharging. The slope is not calculated, and the control circuit is simple and reliable.

[0074] To address the issue of scaling in high-hardness groundwater, this embodiment incorporates an automatic descaling program: a powerful backwash is performed every 24 hours. During backwashing, the polarity switching circuit within the control unit 600 switches the annular negative electrode region 400 to the anode and the positive electrode unit 200 to the cathode, operating at a high current (50mA) for 10 minutes. During this time, an oxidation reaction occurs on the surface of the conductive particle packing 420, generating a large amount of H₂. + The local pH value rapidly drops below 4, quickly dissolving the calcium carbonate scale on the surface; simultaneously, the microbubbles generated by vigorous gas evolution physically peel off the aged biofilm, which is then discharged with the water flow. After backwashing, the polarity is restored, and the system resumes normal denitrification cycle.

[0075] Treatment effect: Under the conditions of influent nitrate nitrogen concentration of 80-150mg / L and total hardness (calculated as CaCO3) of 300-500mg / L, the effluent nitrate nitrogen is stably below 15mg / L. After 90 days of continuous operation, no obvious blockage or performance degradation was observed. The maintenance cycle is more than 3 times longer than that of traditional devices.

[0076] Example 6 The in-well electrobiological denitrification device provided in this embodiment is suitable for remote areas without mains power supply, and can be combined with a photovoltaic system to achieve off-grid operation driven entirely by solar energy.

[0077] In this embodiment, the in-well electrobiological denitrification device adopts a three-stage series configuration: three standard EBD modules are vertically suspended in the well, each with a diameter of 95mm and a length of 1200mm, connected in series via flanges, with a total length of approximately 3.6m, to ensure sufficient contact time even when the influent flow rate is high. The device body 100 of each module is made of UPVC material, equipped with inflatable rubber packers (upper sealing bladder 110 and lower sealing bladder 120) at the top and bottom. The positive electrode unit 200 is a 10mm diameter Ti-MMO hollow tube, the hollow part of which directly forms the exhaust channel 220. The ion-permeable isolation layer 300 is a hydrophobic and breathable membrane (PTFE material, pore size 0.2μm) wrapped around the anode. The annular negative electrode region 400 is filled with 3-5mm high-temperature pyrolytic biochar (i.e., conductive microparticle filler 420) in the annular space between the ion-permeable isolation layer 300 and the device body 100. The reference potential sensor 700 is a solid-state Ag / AgCl reference potential sensor embedded in the center of the cathode bed. A 12V DC micro water pump 500 is integrated at the bottom, with a flow rate set to 15L / h. A 100W monocrystalline silicon photovoltaic panel, an MPPT controller, and a 20Ah lithium iron phosphate battery are provided on the ground to power the device.

[0078] In this embodiment, the in-well electrobiological denitrification device adopts a photo-storage linkage control strategy, executed by the control unit 600. Under continuous flow conditions, a constant potential of -0.5V (vsAg / AgCl) is applied for 14 days until the biofilm matures.

[0079] Under normal operating conditions, the control strategy is linked to day and night light intensity: Daytime Mode (Powerful Purification): Photovoltaic direct drive, battery in float charging state. The system executes high-frequency pulses: the power supply injects electrons into the annular negative electrode region 400 in constant current mode until the cathode potential reaches -0.6V, then switches to constant voltage maintenance until the charging current decays to below 5mA, then pauses for 120 seconds, and repeats the cycle (30 seconds charging / 120 seconds pausing, duty cycle 20%). The abundant photovoltaic power during the day allows the biofilm capacitor to reach electron saturation, while simultaneously reducing the nitrate concentration in the surrounding aquifer to extremely low levels.

[0080] Night Mode (Deep Energy Saving): The system switches to a low sustaining potential mode. During the rest period, the circuit is not completely disconnected, but an extremely low background voltage (-0.1V) is applied to maintain the basic activity of microorganisms; or the rest time is greatly extended (1 minute of charging / 30 minutes of rest, duty cycle of about 3%), relying on the electron reserves accumulated in the pores of conductive microparticle packing 420 (biochar) during the day and the adsorbed pollutants for slow degradation.

[0081] Abnormal protection: If there are consecutive rainy days and the battery voltage is lower than 20%, the control unit 600 will automatically switch to the adsorption priority mode: completely cut off the power supply and use only the physical adsorption capacity of the conductive microparticle filler 420 to intercept pollutants. After the light is restored and the battery voltage rises to above 30%, the normal pulse cycle will be restored by electrochemically regenerating the adsorption sites.

[0082] Treatment effect: Under an average of 4 hours of sunshine per day, the system can maintain continuous operation around the clock. When the influent nitrate nitrogen concentration is 30-60 mg / L, the effluent concentration is consistently below 10 mg / L. It saves approximately 65% ​​energy compared to continuous constant voltage power supply mode, relies entirely on solar energy without external power grid connection, and is suitable for groundwater remediation in remote rural areas, grassland pastoral areas, and other areas without electricity.

[0083] Secondly, this application also provides an in-well adaptive electrobiological denitrification system, including: an in-well electrobiological denitrification device and a control unit 600 as described in any of the above embodiments.

[0084] The control unit 600 is electrically connected to the positive electrode unit 200, the annular negative electrode region 400, the reference potential sensor 700, and the internal circulation drive unit (micro water pump 500), respectively. The control unit 600 is configured to alternately execute a pulse charging phase and a rest phase. During the rest phase, the control unit 600 calculates the denitrification load in real time based on the open circuit potential and its decay slope monitored by the reference potential sensor 700, as well as the pre-acquired Faraday pseudocapacitance value of the electroactive microorganisms, and accordingly adaptively adjusts the duration of the rest phase or the duty cycle of the power supply pulse.

[0085] The in-well adaptive electrobiological denitrification system provided in this application includes the aforementioned in-well electrobiological denitrification device and its matching control unit 600. The control unit 600 is electrically connected to the positive electrode unit 200 (central anode assembly), the annular negative electrode region 400 (including the conductive wire mesh current collector layer 410 and conductive particle packing 420), the reference potential sensor 700 (such as a solid Ag / AgCl reference potential sensor), and the internal circulation drive unit (micro pump 500), realizing fully automatic closed-loop control of the electrochemical denitrification process.

[0086] Specifically, the control unit 600 abandons the traditional constant voltage or timed switching mode, and instead adopts an alternating pulse charging phase and a resting phase. During the pulse charging phase, the control unit 600 injects electrons into the annular negative electrode region 400, charging the electroactive biofilm (attached to the surface of the conductive microparticle packing 420) as a Faraday pseudocapacitor until the cathode potential reaches a preset lower limit (e.g., -0.6V vs. Ag / AgCl) and the charging current decays to a certain percentage below its peak value. At this point, the electrons stored in the biofilm reach saturation. The system then enters the resting phase, where the control unit 600 cuts off the external power supply, allowing the biofilm to continue driving the denitrification reaction using its stored electrons.

[0087] During the resting phase, the control unit 600 uses the open-circuit potential monitored in real time by the reference potential sensor ( ) and its decay slope over time ( ), and the Faraday pseudocapacitance value of electroactive microorganisms calculated in advance through the charging phase ( The current denitrification load is dynamically estimated. Specifically, the control unit executes the following calculation logic:

[0088] in, The real-time denitrification reaction rate (i.e., nitrate reduction load) is given. denoted as Faraday pseudocapacitance of the biomembrane (unit: Faraday), and denoted as the positive rate of change of the open-circuit potential (unit: V / s).

[0089] Based on the above formula, it can be seen that the faster the potential decays (i.e., the larger the absolute value of the slope), the faster the electrons stored in the biofilm are consumed, thus indirectly reflecting that the higher the nitrate concentration in the influent and the stronger the metabolic activity of the microorganisms.

[0090] Based on the real-time calculated denitrification load, when the potential decay slope is large, it indicates that the influent nitrate concentration is high and electron consumption is rapid. The control unit 600 automatically shortens the resting time or ends the resting period early, re-enters the pulse charging stage, and appropriately increases the pulse duty cycle. When the potential decay slope is small and the charge transfer resistance is normal, it indicates that the pollutant concentration is low. The control unit 600 significantly extends the resting time and enters a deep energy-saving mode. At the same time, in order to prevent the deactivation of nitrous oxide reductase and the generation of strong greenhouse gas N2O, the control unit 600 sets a potential safety threshold (e.g., -0.2V). Once the open circuit potential rises to this threshold, regardless of the slope, it forcibly wakes up the charging process to ensure that the reaction endpoint is harmless nitrogen.

[0091] Through the above adaptive control strategy, this system achieves on-demand power supply, which can reduce energy consumption by 30% to 60% compared with continuous constant voltage mode. It also has functions such as health diagnosis and polarity reversal self-cleaning, which significantly improves the energy efficiency and reliability of in-situ remediation of groundwater nitrate pollution.

[0092] Thirdly, this application provides a control method for an in-well electrobiological denitrification system, applied to the system described above. Combined with... Figure 3 As shown, the method includes: S110, during the pulse charging phase, injects electrons into the annular negative electrode region to a set lower limit potential, and estimates the Faraday pseudocapacitance value of the currently electroactive microorganism based on the injected charge and potential difference.

[0093] S120, disconnects the power supply and enters a resting phase to continuously monitor the open circuit potential at a preset sampling frequency.

[0094] S130, calculate the potential decay slope based on the open circuit potential.

[0095] S140 calculates the real-time denitrification rate based on a product correlation model of Faraday pseudocapacitance and potential decay slope.

[0096] S150 adaptively adjusts the duration of the current resting phase based on the comparison between the denitrification rate and a preset threshold.

[0097] S160, during the resting phase, if the real-time monitored open circuit potential drifts positively and touches the preset upper limit safety potential threshold, the current resting phase is forcibly terminated and the pulse charging phase is returned.

[0098] In step S110, during the pulse charging phase, the control unit 600 (MCU) injects electrons into the annular negative electrode region (i.e., the biocathode packing bed) until the cathode potential reaches a preset lower limit potential value (e.g., -0.6V relative to the Ag / AgCl reference potential sensor). This lower limit potential setting needs to consider two aspects: firstly, it must be sufficiently negative to ensure the driving force for electron supply; secondly, it must avoid excessive negativeness leading to hydrogen evolution side reactions (H2 overflow) and energy waste. The charging process typically employs a two-stage constant current-constant voltage strategy: first, rapid charging with a limited current; then, when the potential approaches the lower limit value, switching to constant voltage maintenance until the charging current decays to below 10% of the initial peak value. At this point, it indicates that the cytochrome c protein and conductive matrix within the electroactive biomembrane have reached electron saturation.

[0099] During this charging process, the control unit 600 performs real-time integral calculation of the total injected charge. And record the cathode potential difference before and after charging. Based on the fundamental relationship of electrochemical capacitance, the current Faraday pseudocapacitance value of biological membranes... Calculate using the following formula: .

[0100] This capacitance value (unit: Faraday) is not a fixed constant, but a parameter that changes dynamically with the growth and activity of the biofilm and environmental conditions.

[0101] Step S120: After the charging phase is completed, the control unit immediately cuts off the power supply, and the system enters the resting phase. During this phase, no more electrons are supplied to the cathode externally, but the electroactive denitrifying bacteria attached to the surface of the biochar particles continue to utilize the electrons previously stored in their extracellular polymers and conductive proteins to reduce nitrates to nitrites, nitrogen, and other products. As electrons are continuously consumed, the open-circuit potential of the cathode (…) It will gradually drift in the positive direction (i.e., the potential increases).

[0102] The control unit continuously monitors the open-circuit potential signal fed back by the reference potential sensor (solid-state Ag / AgCl reference potential sensor) at a preset high sampling frequency (e.g., greater than 10Hz, preferably 10Hz to 100Hz). The purpose of high-frequency sampling is to capture subtle changes in potential, thereby accurately calculating the subsequent attenuation slope. This step does not consume external power and is a zero-power operation phase.

[0103] In step S130, during the resting phase, the control unit continuously collects the open-circuit potential. The slope of potential decay is calculated by numerical differentiation of the change over time. .

[0104] Since the open circuit potential typically shifts monotonically positive (potential increases) during the resting phase, the slope is positive, but its magnitude (absolute value) reflects the rate of electron consumption. From a bioelectrochemical kinetics perspective: if the influent nitrate concentration is high, the microbial metabolism is vigorous, rapidly consuming the electrons stored in the biofilm, leading to a rapid positive shift in the open circuit potential. The concentration is relatively high; conversely, if the pollutant concentration is close to meeting the standard, the electron demand of microorganisms decreases, and the positive shift of the potential is slow. The potential decay slope is relatively small. Therefore, this potential decay slope is essentially a virtual sensor signal that can reflect the pollutant load in real time, and reaction rate information can be obtained without the need to install an expensive online nitrate analyzer.

[0105] Step S140: The Faraday pseudocapacitance value estimated in step S110 is used. The potential decay slope calculated in step S130 By performing correlation, the following product model is constructed to estimate the real-time denitrification rate:

[0106] in, The negative sign represents the rate of denitrification (usually expressed as the amount of nitrate nitrogen reduced per unit time) to make the rate value positive (because...). (Positive). The physical basis of this model lies in the amount of charge stored in the biomembrane capacitor. The rate of charge consumption The rate of charge consumption is directly proportional to the rate at which electrons are used for denitrification. Since the change in open-circuit potential directly reflects the consumption of stored charge, the rate of charge consumption can be obtained by multiplying the potential decay slope by the capacitance, which is then correlated with the denitrification rate. The virtual sensing method used in this application avoids the lag in traditional electrochemical systems that require additional detection of nitrate concentration, achieving millisecond-level real-time estimation of the reaction rate.

[0107] In step S150, the control unit calculates the real-time denitrification rate obtained in step S140. It is compared with one or more pre-calibrated preset thresholds, and the preset time length of the current rest phase is dynamically adjusted (or the duty cycle of the next pulse cycle is adjusted equivalently) based on the comparison results.

[0108] In conjunction with the third aspect, step S150 includes: S151, if If the condition is determined to be a high-load condition, the resting time is shortened or the resting period is ended early, and the pulse charging phase of step S1 is restarted.

[0109] S152, if and Within the preset reference range, it is determined to be a low-load operating condition, and the resting period is extended before it rises back to the upper limit safety potential threshold.

[0110] S153, if and If the value exceeds the preset baseline range, it is determined to be a loss of microbial activity, and a shutdown and alarm mode is executed.

[0111] in, This represents the denitrification rate; The first threshold was obtained by pre-calibrating high-concentration polluted groundwater; This is the second threshold obtained by pre-calibrating the water quality to meet the standards; This is the system charge transfer resistance.

[0112] Step S150 calculates the real-time denitrification rate. With two preset thresholds A comparison is made, while introducing the system charge transfer resistance. As an auxiliary criterion, the system operating state is divided into three scenarios: high-load condition, low-load normal condition, and microbial inactivation / fault condition, and differentiated control actions are executed for each. This refined decision-making logic significantly improves the system's robustness and fault diagnosis capability, avoiding misjudgments that may result from relying solely on the denitrification rate (e.g., when microbial poisoning occurs). The readings will also be very low, but this does not mean the water quality meets standards; rather, it indicates a system failure. The following explains each of the three sub-steps: Step S151, when the control unit determines At that time, the system identified it as a high-load operating condition. Among them, The first threshold, obtained by prior calibration of highly polluted groundwater (e.g., nitrate nitrogen concentration >50 mg / L or higher), represents the higher load boundary that the system can economically handle. A level above this threshold means a sudden increase in influent nitrate concentration, rapid consumption of electrons, and a state of microbial starvation, where the electrons stored during the existing resting phase are insufficient to meet the pollutant removal requirements.

[0113] In this situation, the control unit performs actions including: actively shortening the remaining time of the current resting phase, or directly forcibly ending the resting phase and immediately restarting the pulse charging phase (i.e., step S110). Simultaneously, to cope with continuous high load surges, the system also increases the duty cycle of subsequent pulse cycles accordingly (e.g., increasing the charging time ratio from the usual 30% to 70%), ensuring that more electron reserves are injected in the next cycle. This rapid response mechanism prevents incomplete treatment or accumulation of intermediate products (such as nitrite) due to insufficient electron supply, ensuring the stability of the effluent water quality.

[0114] In step S152, when the control unit determines And the system charge transfer resistance When the load is within the preset normal baseline range, the system identifies it as a low-load normal operating condition. This is a second threshold obtained by pre-calibrating water quality to meet standards (e.g., nitrate nitrogen <10mg / L), indicating that pollutants have been largely removed; This is an electrochemical parameter reflecting the ease of electron transfer at the electrode / biofilm interface, and its normal range can be obtained through calibration at the initial stage of biofilm formation. The simultaneous fulfillment of both parameters indicates that the low denitrification rate is indeed due to low pollutant concentration, rather than loss of microbial activity.

[0115] Under this operating condition, the control unit performs the following actions: significantly extending the duration of the current rest phase, allowing the open circuit potential to slowly shift positive without external power supply, and even allowing it to rise back to the preset upper limit safety potential threshold. This deep rest mode keeps the system in a zero-energy state most of the time, triggering the next charging cycle only when the potential reaches the safety threshold. Compared to the conventional rest duration, this mode can reduce the pulse duty cycle to 5%–10%, thereby achieving extreme energy-saving effects (more than 50% energy saving compared to continuous constant pressure mode), while still maintaining compliant water output.

[0116] In step S153, when the control unit determines However, the system charge transfer resistance When the concentration significantly exceeds the preset normal baseline range (e.g., more than 2 times or more above the baseline value), the system identifies it as a loss of microbial activity or a system malfunction. The logic behind this judgment is: if the low contaminant concentration is the cause... The only reason for smallness, then It should be maintained at a normal level (because the biofilm interface remains healthy); conversely, if... An abnormally high level indicates that the pathway for electrons to transfer from the biofilm to nitrates is blocked. Possible causes include: microbial poisoning (such as the presence of toxic substances in the influent), excessive aging or shedding of the biofilm, severe scaling on the packing surface, or poor electrode contact.

[0117] In this situation, continued operation not only fails to effectively remove contaminants but may also waste energy and accelerate system damage. Therefore, the control unit performs the following actions: immediately cut off the power supply, stop pulse charging and the rest cycle, and simultaneously output audible and visual alarm signals or wireless alarm information to the ground monitoring system through the waterproof cable interface, prompting maintenance personnel to perform manual intervention (such as well inspection, replacement of packing material, re-attaching film, etc.). This self-diagnostic and protection function is particularly important for deep well in-situ repair systems because the equipment is buried underground, making it impossible to visually determine its operating status. This method achieves intelligent early warning through changes in electrochemical impedance characteristics, greatly reducing the risk of blind operation and the cost of manual inspection.

[0118] In conjunction with the third aspect, prior to step S110, the following also includes: S010, at the beginning of each control cycle, a high-frequency probe pulse lasting 100ms is applied to the concentric electrode device to collect the transient current response and calculate the solution resistance.

[0119] S020, calculate the rate of change of resistance based on the solution resistance of adjacent periods.

[0120] S030, if the resistance change rate is higher than the preset threshold, it is determined that air accumulation or scaling has occurred in the packing gap, triggering the maintenance regeneration mode.

[0121] S040, if the resistance change rate is lower than the preset threshold, the resistance change rate is determined to be stable.

[0122] Before each complete pulse charge-rest control cycle begins in step S110, the control unit first performs a rapid non-destructive diagnostic.

[0123] Specifically, the control unit applies a high-frequency micro-perturbation pulse with a duration of 100 milliseconds to the concentric electrode device (between the positive electrode unit and the annular negative electrode region) inside the well via a signal generation circuit. The frequency range of this pulse is typically set between 1 kHz and 10 kHz, and the voltage perturbation amplitude is controlled between 10 mV and 50 mV. Such parameter settings can effectively stimulate the ohmic response of the system without significantly interfering with the normal metabolism of the biomembrane or causing obvious Faraday reactions.

[0124] While applying the pulse, the control unit acquires the transient current response signal at a high sampling rate. Based on Ohm's law or the simplified principle of electrochemical impedance spectroscopy (EIS), the solution ohmic resistance Rs of the electrode system (especially the cathode packed bed) under the current state can be calculated by analyzing the proportional relationship between the voltage perturbation and the current response. This resistance mainly reflects the ionic conductivity of the groundwater electrolyte in the pores of the packing material and is extremely sensitive to the accumulation of air bubbles (gas resistance) or scaling of inorganic salts such as calcium carbonate in the packing gaps.

[0125] Step S020: Solution resistance obtained from a single measurement The absolute value is greatly affected by environmental factors such as groundwater salinity and temperature. Therefore, this method does not directly use the absolute value as a judgment basis, but instead uses the dynamic trend as a diagnostic indicator. The control unit will use the values ​​measured in the current period... The measurement obtained from the previous control cycle Compare and calculate the rate of change of resistance: .

[0126] This rate of change reflects the fluctuation range of solution resistance between two adjacent cycles. Under normal operating conditions, due to the relatively stable groundwater quality and the pore structure of the packing material, the rate of resistance change should be maintained within a small range (e.g., ±5% to ±10%). This indicator will respond rapidly to any abnormal changes.

[0127] In step S030, when the control unit calculates the resistance change rate... If the change rate is significantly higher than the preset threshold (e.g., change rate > 20% to 30%, the specific threshold can be determined based on previous experiments), the system determines that gas accumulation or scaling has occurred in the gap of the cathode packing.

[0128] Among them, gas accumulation occurs when trace amounts of oxygen generated at the anode are not completely discharged through the exhaust channel during long-term operation, or when nitrogen (N2) bubbles generated during the denitrification process are retained in the packing pores, which will form gas resistance, resulting in discontinuity of the liquid phase ion channel, manifested as a sharp increase in solution resistance.

[0129] Scaling occurs when, in hard groundwater, the increased pH near the cathode causes sparingly soluble salts such as calcium carbonate (CaCO3) to precipitate on the surface of biochar particles, which can also clog pores and increase electrical resistance.

[0130] Once the above-mentioned abnormal operating conditions are confirmed, the control unit will trigger the maintenance regeneration mode (i.e., the in-situ electrochemical self-cleaning procedure). This mode typically includes: polarity reversal (switching the original cathode to the anode, and the original anode to the cathode), applying a high current 2 to 5 times higher than the normal operating current for 5 to 10 minutes, utilizing the local acidic environment (pH < 4) generated by the anodic oxidation reaction to dissolve inorganic scale, and simultaneously using the shear force of microbubbles generated by intense gas evolution to peel off the aged biofilm, thereby restoring the permeability and conductivity of the packed bed without well removal. After regeneration is completed, the system automatically resets and restarts the normal control cycle.

[0131] In step S040, when the control unit calculates the resistance change rate... When the resistance change rate is below or equal to the preset threshold, the system determines that the resistance change rate is stable, meaning that there is no obvious gas accumulation or scaling in the packing gap and the physical condition of the electrode system is good. At this time, the control unit confirms that the system is in a healthy state and does not need to execute the maintenance regeneration procedure. It then normally enters the pulse charging stage of step S110 and continues to operate according to the adaptive control process of "pulse charging - rest".

[0132] This decision branch ensures that, for the vast majority of normal operating times, the system will not perform unnecessary polarity reversal cleaning due to accidental triggering, thus avoiding excessive disturbance to the biofilm and additional energy consumption during the cleaning process. Simultaneously, this steady state provides a reliable electrochemical environment for calculating the denitrification rate based on the open-circuit potential slope in subsequent steps (because...). Abnormal fluctuations can directly interfere with the accuracy of potential measurements.

[0133] The pre-diagnostic mechanism consisting of steps S010-S040 completes a physical examination at the beginning of each control cycle in a very short time (100 milliseconds) and with very low energy consumption. Through trend analysis of the solution resistance change rate, it realizes remote, non-destructive, and real-time assessment of the physical status of the downhole device. This enables the system to proactively initiate self-cleaning before serious blockage or gas blockage occurs, or to promptly alarm when self-healing is not possible, thereby extending the maintenance-free operation cycle of the device. It is particularly suitable for application scenarios such as rural decentralized water supply wells that lack professional operation and maintenance personnel.

[0134] In conjunction with the third aspect, after step S030, which triggers the maintenance regeneration mode, the following steps are also included: S031, through the polarity switching circuit, temporarily switches the positive pole unit of the central axis to the negative pole of the power supply, and temporarily switches the annular negative pole area to the positive pole of the power supply.

[0135] S032 operates at a preset high current for a preset time, using the acidic environment generated in the annular negative electrode region to dissolve inorganic carbonate scale, and using the shearing force of the generated microbubbles to peel off the aged electroactive microbial membrane.

[0136] S033, after cleaning, restore the polarity of the electrode and re-enter the normal pulse control cycle.

[0137] When the control unit determines in step S030 that gas accumulation or scaling has occurred in the filler gap and triggers the maintenance and regeneration mode, the first operation performed is a temporary reversal of the electrode polarity. Specifically, the polarity switching circuit inside the control unit (e.g., an H-bridge relay array composed of MOSFETs or IGBTs, or a solid-state switching module) changes the connection relationship between the DC power output terminal and the electrode according to the instruction: the positive electrode unit (i.e., the anode assembly) originally located on the central axis is temporarily switched to the negative electrode of the power supply, making it a temporary cathode; at the same time, the annular negative electrode area (including the conductive wire mesh current collector and the conductive particle filler) is temporarily switched to the positive electrode of the power supply, making it a temporary anode. This polarity reversal is the key start-up step of the entire self-cleaning process, and its purpose is to achieve the cleaning function by utilizing the reverse process of the electrochemical oxidation-reduction reaction without changing the structure of the device or adding additional cleaning components.

[0138] After the polarity reversal is complete, the control unit applies a preset high current (typically 2 to 5 times higher than the normal operating current density, for example, set to 50–100 A / m). 2 The system operates continuously for a preset time (e.g., 5 to 10 minutes). Under this high current density condition, the biochar packing bed, which was originally the cathode, becomes the anode, and its surface undergoes a strong oxidation reaction, producing the following two synergistic cleaning effects: Chemical dissolution of inorganic carbonate scale: The oxidation reaction generates a large number of hydrogen ions, causing the local pH value on the surface of biochar particles to drop sharply to below 4. This highly acidic environment can rapidly dissolve inorganic salt scale such as calcium carbonate deposited in the pores and surface of the packing material during long-term operation, converting it into soluble calcium ions, which are then discharged from the reactor with groundwater flow, thereby restoring the permeability and effective specific surface area of ​​the packing material.

[0139] Physical stripping of aged electroactive biofilm: Simultaneously, micron-sized oxygen bubbles generated by the anodic oxygen evolution reaction violently form and rise to the surface of the biochar. These bubbles generate strong local shear forces during detachment, physically stripping overgrown, deactivated, or dead electroactive microbial biofilms from the carrier surface, which are then carried away in flocculent form by the water flow. This physical stripping process avoids mass transfer blockage and decreased electron transport efficiency caused by excessive accumulation of aged biofilm.

[0140] The aforementioned dual cleaning process enables in-situ regeneration of the cathode packing bed without raising the device to the surface. Compared to traditional manual well-lifting cleaning or chemical cleaning, this method has significant advantages such as ease of operation, no introduction of foreign chemicals, and no impact on subsequent biofilm re-attachment.

[0141] After the cleaning process is completed, the electrode polarity is restored and the normal pulse control cycle is restarted. After the preset cleaning time (e.g., 5-10 minutes), the control unit first cuts off the cleaning current, and then restores the electrode polarity to its original connection state through the polarity switching circuit: the central axis unit is reconnected to the positive terminal of the power supply (restored as the positive unit / anode), and the annular negative electrode area is reconnected to the negative terminal of the power supply (restored as the negative electrode area / cathode). After the polarity is restored, the control unit automatically exits the maintenance regeneration mode and re-enters the normal pulse charging-rest control cycle (usually starting from the pre-diagnosis in step S010 or the pulse charging stage in step S110). At this time, the surface of the cleaned biochar packing is clean and the pores are open, allowing residual or newly inoculated microorganisms to quickly re-column on the new surface and restore denitrification activity. Typically, within a few hours to one or two days of resuming operation, the system's treatment performance can reach or even exceed the level before cleaning.

[0142] Steps S031 to S033, through periodic polarity reversal and high-current oxidation, effectively solve the two major engineering challenges commonly faced in in-situ groundwater remediation: biological blockage and inorganic scaling, by exchanging electrical energy for labor maintenance costs. This function is particularly suitable for scenarios such as decentralized rural water supply wells and monitoring wells in agricultural irrigation areas where there is a lack of professional operation and maintenance personnel and well-lifting operations are difficult. It helps to extend the maintenance-free operation cycle of the device (from several weeks to several months or even longer), improving the practicality and economy of the technology.

[0143] Combination Figure 4 As shown, the control unit 600 of this application embodiment includes a memory 602 and a processor 601. The memory 602 is used to store computer programs, and the processor 601 runs the computer programs to make the electronic device perform the above-described methods.

[0144] Furthermore, combined Figure 4The electronic device shown also includes a bus 603 and a communication interface 604. The processor 601, the communication interface 604, and the memory 602 are connected via the bus 603.

[0145] The memory 602 may include high-speed random access memory (RAM) and may also include non-volatile memory, such as at least one disk storage device. Communication between this system network element and at least one other network element is achieved through at least one communication interface 604 (which can be wired or wireless), such as the Internet, wide area network, local area network, metropolitan area network, etc. The bus 603 may be an ISA bus, PCI bus, or EISA bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 4 The symbol is represented by a single double-headed arrow, but this does not mean that there is only one bus or one type of bus.

[0146] Processor 601 may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method can be completed by the integrated logic circuitry in the hardware of processor 601 or by instructions in software form. The processor 601 can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly manifested as execution by a hardware decoding processor, or execution by a combination of hardware and software modules in the decoding processor. The software module can reside in a mature storage medium in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory 602. The processor 601 reads the information in memory 602 and, in conjunction with its hardware, completes the steps of the method described in the foregoing embodiments.

[0147] Fifthly, embodiments of this application provide a readable storage medium storing computer program instructions, which are read and executed by a processor to perform the above-described method.

[0148] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and apparatus described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0149] Furthermore, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0150] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0151] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0152] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An in-well electrobiological denitrification device, characterized in that, The device includes: The device body is located inside the well, with an inlet on the lower part of the side wall and an outlet on the upper part. A concentric electrode device is disposed within the main body of the device; the concentric electrode device includes a positive electrode unit located on the central axis, an annular negative electrode region arranged around the positive electrode unit, an ion-permeable isolation layer disposed between the positive electrode unit and the annular negative electrode region, and a reference potential sensor embedded inside the annular negative electrode region; wherein, the annular negative electrode region is filled with conductive microparticle filler, the conductive microparticle filler being used to load electroactive microorganisms and form a charge temporary storage medium; A gas barrier emission assembly is arranged around the outside of the positive electrode unit to physically isolate the gas generated by the positive electrode from the annular negative electrode region and guide it to the outside. The internal circulation drive unit includes a micro water pump and a diversion pipe, which is used to force groundwater to flow from bottom to top in the annular negative electrode area; An expansion sealing assembly, including an upper sealing bladder located on the top periphery of the device body and a lower sealing bladder located on the bottom periphery, is used to isolate the well section where the device is located from the external wellbore. The positive electrode unit, the annular negative electrode region, the reference potential sensor, and the internal circulation drive unit are electrically connected to the control unit. The control unit is configured to alternately execute a pulse charging phase and a resting phase. During the resting phase, the control unit calculates the denitrification load in real time based on the open circuit potential and its decay slope monitored by the reference potential sensor, as well as the pre-acquired Faraday pseudocapacitance value of the electroactive microorganisms, and adaptively adjusts the duration of the resting phase or the duty cycle of the power supply pulse accordingly.

2. The apparatus according to claim 1, characterized in that, The gas barrier emission assembly is a porous insulating sleeve fitted outside the positive electrode unit, and the internal cavity of the porous insulating sleeve forms an exhaust channel communicating with the atmosphere; Alternatively, the gas barrier emission component may be a hydrophobic and breathable membrane wrapped around the surface of the positive electrode unit.

3. The apparatus according to claim 1, characterized in that, The positive electrode unit is a hollow tubular structure, and its hollow part forms an exhaust channel.

4. The apparatus according to claim 1, characterized in that, The annular negative electrode region also includes a conductive wire mesh current collector layer disposed close to the inner wall of the device body, and the conductive microparticle filler is filled between the conductive wire mesh current collector layer and the ion permeable isolation layer; the conductive microparticle filler is pyrolytic biochar particles, or a mixture of pyrolytic biochar and zero-valent iron particles.

5. The apparatus according to claim 1, characterized in that, The top of the device body is also equipped with a load-bearing lifting ring and a waterproof cable interface.

6. A well electrobiological denitrification system, characterized in that, include: The in-well electrobiological denitrification device as described in any one of claims 1-5; The control unit is electrically connected to the positive electrode unit, the annular negative electrode region, the reference potential sensor, and the internal circulation drive unit, respectively. The control unit is configured to alternately execute a pulse charging phase and a resting phase; during the resting phase, the control unit calculates the denitrification load in real time based on the open circuit potential and its decay slope monitored by the reference potential sensor, as well as the pre-acquired Faraday pseudocapacitance value of the electroactive microorganism, and accordingly adaptively adjusts the duration of the resting phase or the duty cycle of the power supply pulse.

7. A control method for an in-well electrobiological denitrification system, characterized in that, Applied to the system as described in claim 6; the method includes: During the pulse charging phase, electrons are injected into the annular negative electrode region to a set lower limit potential, and the Faraday pseudocapacitance value of the current electroactive microorganism is estimated based on the injected charge and potential difference. The power supply is then cut off to enter a resting phase where the open-circuit potential is continuously monitored at a preset sampling frequency. Based on the open-circuit potential, the potential decay slope is calculated. The real-time denitrification rate is calculated based on a correlation model of the Faraday pseudocapacitance value and the potential decay slope. The duration of the current resting phase is adaptively adjusted based on a comparison between the denitrification rate and a preset threshold. During the resting phase, if the real-time monitored open-circuit potential drifts positively and touches a preset upper safety potential threshold, the current resting phase is forcibly terminated, and the system returns to the pulse charging phase.

8. The method according to claim 7, characterized in that, The step of adaptively adjusting the duration of the current resting phase based on the comparison between the denitrification rate and a preset threshold includes: like If the condition is determined to be a high-load condition, the resting time is shortened or the resting period is ended early, and the pulse charging phase is restarted. like and Within the preset benchmark range, it is determined to be a low-load operating condition, and the resting time is extended until it rises back to the upper limit safety potential threshold. like and If the value exceeds the preset baseline range, it is determined to be a loss of microbial activity, and a shutdown and alarm mode is activated. in, The denitrification rate is mentioned above. The first threshold was obtained by pre-calibrating high-concentration polluted groundwater; This is the second threshold obtained by pre-calibrating the water quality to meet the standards; This is the system charge transfer resistance.

9. The method according to claim 7, characterized in that, Before the step of injecting electrons into the annular negative electrode region to a set lower limit potential during the pulse charging phase, and estimating the Faraday pseudocapacitance value of the currently electroactive microorganism based on the injected charge and potential difference, the method further includes: At the beginning of each control cycle, a high-frequency probe pulse lasting 100ms is applied to the concentric electrode device to collect the transient current response and calculate the solution resistance; The rate of change of resistance is calculated based on the solution resistance of adjacent periods; If the resistance change rate is higher than a preset threshold, it is determined that air accumulation or scaling has occurred in the packing gap, triggering the maintenance and regeneration mode. If the rate of change of resistance is lower than the preset threshold, the rate of change of resistance is determined to be stable.

10. The method according to claim 9, characterized in that, Following the step of triggering the maintenance regeneration mode, the method further includes: By using a polarity switching circuit, the positive pole unit of the central axis is temporarily switched to be connected to the negative pole of the power supply, and the annular negative pole region is temporarily switched to be connected to the positive pole of the power supply. Running at a preset high current for a preset time, the acidic environment generated in the annular negative electrode region is used to dissolve inorganic carbonate scale, and the shearing force of the generated microbubbles is used to peel off the aged electroactive microbial membrane. After cleaning, the electrode polarity is restored and the normal pulse control cycle is restarted.

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