Dual-electrode denitrification system and agricultural underground water rapid denitrification technology

Abstract

The invention relates to the technical field of water pollution treatment, and particularly discloses a dual-electrode denitrification system and an agricultural underground water rapid denitrification technology.The system comprises a cathode assembly, an anode assembly and a power source, a first reaction part is arranged on the surface of the cathode assembly, and the cathode assembly is used for conducting a reduction reaction on compounds in a water body through the first reaction part; a second reaction part is arranged on the surface of the anode assembly, the anode assembly is used for conducting oxidation reaction on compounds in the water through the second reaction part, the power source is electrically connected with the cathode assembly and the anode assembly, and the power source is used for providing positive potential for the anode assembly, so that electrons flow to the anode assembly from the cathode assembly. The denitrification device has the effect of improving the problem of poor adaptability of the existing denitrification device.

Description

Technical Field

[0001] The present application relates to the technical field of water pollution control, and in particular to a dual-electrode denitrification system and a rapid denitrification technology for agricultural groundwater. Background Art

[0002] With the excessive use of agricultural fertilizers, groundwater contamination with ammonia and nitrate nitrogen has become a global environmental problem, posing a serious threat to ecosystems and human health. While traditional remediation technologies, such as biological nitrification and denitrification and permeable reaction wall technology, have some applications, they have significant limitations.

[0003] The biological nitrification and denitrification method relies on microbial metabolism, has a long treatment cycle, a complex system, and is greatly affected by environmental factors, making it difficult to achieve efficient and stable operation; the permeable reaction wall technology is difficult to adapt to the dynamically changing groundwater pollution environment because the reaction material is easily saturated and fails, the installation is complex, and real-time monitoring is impossible. Summary of the Invention

[0004] In order to improve the problem of poor adaptability of existing denitrification devices, the present application provides a dual-electrode denitrification system and a rapid denitrification technology for agricultural groundwater.

[0005] In the first aspect, the present application provides a dual-electrode denitrification system that adopts the following technical solutions: A dual-electrode denitrification system comprising: A cathode assembly, having a first reaction element disposed on its surface, for performing a reduction reaction on compounds in the water body through the first reaction element; an anode assembly, the surface of which is provided with a second reaction member, for performing an oxidation reaction on compounds in the water body through the second reaction member; The power supply is electrically connected to the cathode assembly and the anode assembly respectively, and is used to provide a positive potential to the anode assembly so that electrons flow from the cathode assembly to the anode assembly.

[0006] By adopting the above technical solution, the power supply is electrically connected to the cathode assembly and the anode assembly, providing a positive potential to the anode assembly, thereby forming a potential difference, allowing electrons to flow from the anode assembly to the cathode assembly; the surface of the cathode assembly is provided with a first reaction element, whose main function is to reduce the compounds in the water body through the first reaction element. In the electrochemical system, the cathode receives electrons, which are used by the first reaction element to drive the reduction reaction. For example, for nitrate nitrogen in water , the first reaction piece can reduce it to nitrogen Or other harmless nitrogen compounds, thereby achieving the removal of nitrogen pollutants in the water body. The surface of the anode assembly is provided with a second reaction element, whose main function is to oxidize the compounds in the water body through the second reaction element. In the electrochemical system, the anode releases electrons. The loss of these electrons makes the anode surface positively charged, thereby attracting reducing substances in the water body to the anode. Under the action of the anode surface, the second reaction element can oxidize and decompose reducing substances (such as organic pollutants) in the water body, converting them into harmless substances such as carbon dioxide and water, thereby achieving the purpose of purifying water quality, improving the poor adaptability of existing denitrification equipment, and improving denitrification efficiency. It is particularly suitable for rapid denitrification treatment of agricultural groundwater and has good application prospects and environmental benefits.

[0007] Preferably, the anode assembly is cylindrical and provided with a plurality of meshes, and is one or more of titanium electrodes.

[0008] By adopting the above technical solution, the cylindrical anode assembly can increase the contact area with the electrolyte, thereby improving the electron transfer efficiency and enhancing the denitrification capacity of the system. The metal electrode has good hardness and conductivity, and the hard mesh structure surrounding the cathode assembly can prevent the external filler from damaging the internal cathode assembly under the action of water force.

[0009] Preferably, the diameter of the anode assembly is 28 cm to 52 cm.

[0010] By adopting the above technical solution and setting the diameter of the anode assembly, the distance between the anode assembly and the cathode assembly can be ensured, the internal resistance of the water in the middle can be avoided to be too large, and the strength of the electrode electric field formed can be ensured, thereby stably generating effective current data.

[0011] Preferably, the cathode assembly is cylindrical, is disposed inside the anode assembly, and is coaxially disposed with the anode assembly. The cathode assembly is a combination of one or more carbon-based materials, metal materials, and conductive polymers.

[0012] By adopting the above technical solution, the cathode assembly is cylindrical and coaxially arranged with the anode assembly, which can ensure that the distance between the cathode assembly and the anode assembly is uniform and fixed, forming a stable electric field distribution, which is conducive to the smooth flow of electrons from the cathode assembly to the anode assembly, ensuring the efficient progress of the reduction reaction; at the same time, the cylindrical structure of the cathode assembly can maximize the contact area with the compound, increase the reaction rate, and further improve the denitrification efficiency of the system. The combination of one or more combinations of carbon materials, metal materials, and conductive polymers can not only improve the denitrification efficiency, but also enhance the stability and adaptability of the system.

[0013] Preferably, the diameter of the cathode assembly is 8 cm to 32 cm.

[0014] By adopting the above technical solution, if the width of the cathode assembly is too small, the position where microorganisms can attach is too small, which will affect the denitrification effect; if the width is too large, the current generated is too large, which is easy to affect the current data and cause data changes. Therefore, the width of the cathode assembly is preferably 10~30cm; setting the diameter of the cathode assembly within the range of 8cm to 32cm can ensure that a suitable electrode spacing is formed between the cathode assembly and the anode assembly, thereby generating a stable current density and electric field distribution between the two.

[0015] Preferably, the first reaction member and the second reaction member are both microbial membranes, and the first reaction member and the second reaction member are cultured in situ on the surfaces of the cathode assembly and the anode assembly.

[0016] By adopting the above technical solution, the first reaction element (reducing microbial film) on the surface of the cathode assembly can be cultured in situ and can efficiently use the electrons provided by the cathode to reduce compounds in the water (such as nitrate nitrogen). The microorganisms in these microbial films can directly or indirectly use the electrode electrons to transfer them to nitrate nitrogen. or nitrite nitrogen , which is reduced to nitrogen Or other harmless nitrogen compounds; the second reaction element (microbial film) on the surface of the anode component can oxidize the compounds in the water through in-situ cultivation; the in-situ cultured microbial film is closely integrated with the cathode surface, which improves the efficiency of electron transfer and enhances the stability of the microbial film during the reaction. In addition, this biocatalytic method can be carried out under mild conditions, avoiding the high energy consumption and secondary pollution problems that may be caused by traditional chemical reduction methods; on the anode surface, the microorganisms in the microbial film can reduce organic matter or ammonia nitrogen in the water. As an electron donor, it oxidizes and transfers electrons to the anode to generate current. As an electron donor, it is oxidized to or other oxidized substances; the microbial membranes on the cathode and anode components achieve synergistic denitrification of compounds in the water through electron transfer in the electrochemical system. The oxidation reaction at the anode and the reduction reaction at the cathode work together to more efficiently remove nitrogen pollutants from the water.

[0017] Preferably, the cathode assembly and the anode assembly have the same length, which is 4m to 8m.

[0018] By adopting the above technical solution, the cathode and anode assemblies are of equal length and coaxially arranged, ensuring a symmetrical electric field distribution during the electrochemical reaction. This symmetry facilitates uniform electron transfer and contact with reactants, thereby improving the overall reaction efficiency of the system. Longer electrode lengths significantly increase the contact area between the cathode and anode and the water. Within a length range of 4 to 8 meters, the cathode and anode can more fully contact compounds in the water, thereby increasing the rates of reduction and oxidation reactions. Longer electrode lengths can treat larger volumes of water, making them suitable for large-scale agricultural groundwater denitrification. This design enables the system to efficiently treat high groundwater flows, meeting the large-scale treatment requirements of practical applications. By increasing the electrode length, the cathode and anode can more effectively contact pollutants in the water, thereby increasing the rates of reduction and oxidation reactions. Longer electrode lengths ensure that more microbial membranes come into contact with pollutants, further improving denitrification efficiency. Furthermore, since groundwater is often located at a depth of 6 meters below the surface and varies in depth from region to region, the preferred length of the anode and cathode assemblies is 4 to 8 meters.

[0019] Preferably, an aeration plate is further included, which is arranged at one end of the anode assembly and fixedly connected to the anode assembly.

[0020] By adopting the above technical solution, the main function of the aeration plate is to provide oxygen to the system. In the oxidation reaction process of the anode component, oxygen can act as an electron acceptor and participate in the oxidation reaction, thereby promoting the metabolic activity of the microbial film on the anode surface. For example, in the oxidation of ammonia nitrogen at the anode During the oxidation process, oxygen can accept electrons, producing water or other harmless substances, thereby driving the oxidation reaction. By introducing air into the system, aeration discs enhance water mixing and mass transfer. The rising bubbles agitate the water, allowing pollutants (such as ammonia nitrogen and nitrate nitrogen) to fully contact the microbial film on the electrode surface, thereby increasing the reaction rate. The oxygen provided by the aeration disc maintains the activity of the microbial film on the anode surface. Microorganisms in the microbial film require oxygen for aerobic respiration to maintain normal metabolic activity. Continuous oxygen supply from the aeration disc ensures efficient microbial film activity during the oxidation reaction, thereby improving the system's denitrification efficiency. Aeration discs feature small bubbles, a large gas-liquid interface, uniform bubble diffusion, strong corrosion resistance, and high oxygen utilization, making them a preferred aeration device.

[0021] Preferably, a reaction medium is also included, which is arranged in the cathode assembly and between the anode assembly and the cathode assembly. The reaction medium is used to provide the necessary ion environment for the electrochemical reaction of the anode assembly and the cathode assembly to ensure the transfer of electrons and protons.

[0022] By adopting the above technical solution, the reaction medium provides the necessary ionic environment and enhanced conductivity, significantly increasing the electrochemical reaction rates at the anode and cathode, thereby improving the system's denitrification efficiency. For example, during the oxidation of ammonia nitrogen at the anode and the reduction of nitrate nitrogen at the cathode, the ions in the reaction medium accelerate the transfer of electrons and protons, increasing the reaction rate. The reaction medium also ensures charge balance and pH stability in the system, thereby optimizing overall system performance. A stable charge balance and pH environment contribute to the long-term stable operation of the microbial biofilm and reduce fluctuations in microbial activity. The use of the reaction medium reduces the need for external chemical reagents, such as acids, bases, or buffers. The reaction medium's inherent buffering effect maintains a stable pH, thereby reducing operating costs. The reaction medium also buffers the acid-base fluctuations generated during the reaction, reducing the impact of pH fluctuations on the microbial biofilm and thus improving system stability. Furthermore, the ions in the reaction medium neutralize the charge generated on the electrode surfaces, reducing electrode polarization and further enhancing system stability.

[0023] In the second aspect, the present application provides a technology for rapid denitrification of agricultural groundwater, which adopts the following technical solution: A rapid denitrification technology for agricultural groundwater comprises the following steps: Drill wells according to actual needs and the established specifications of the dual-electrode denitrification system; Cultivating a first reaction member and a second reaction member on surfaces of the anode assembly and the cathode assembly; Place the dual-electrode denitrification system into the well and connect the power supply and the dual-electrode denitrification system; The reaction medium is filled and a voltage is applied to the anode.

[0024] By adopting this technical solution, microbial membranes are cultivated on both the cathode and anode surfaces, enabling simultaneous reduction and oxidation reactions. The cathode membrane uses electrons to reduce nitrate or nitrite nitrogen, while the anode membrane uses oxidation to treat ammonia or other organic pollutants, achieving efficient denitrification. The membranes can efficiently utilize electrons provided by the electrodes or act as electron donors in the reaction, significantly improving reaction rate and denitrification efficiency. Compared to traditional chemical denitrification methods, this reduces reaction time and energy consumption. Installing a dual-electrode denitrification system in a groundwater well directly treats groundwater without pumping it out of the ground, reducing energy consumption and the risk of secondary contamination during treatment. This also lowers system operating costs. The system can be adjusted based on groundwater quality and quantity, making it suitable for treating groundwater in different regions and with varying degrees of contamination, offering wide applicability. The entire system features a simple design and easy installation: simply follow the steps of drilling the well, cultivating the membranes, installing the system, filling the reaction medium, and applying voltage. During operation, efficient denitrification is achieved by controlling the power supply voltage, making it easy to operate and suitable for widespread application in agricultural areas.

[0025] In summary, this application includes at least one of the following beneficial technical effects: 1. The power supply is electrically connected to the cathode assembly and the anode assembly, providing a positive potential to the anode assembly, thereby forming a potential difference, allowing electrons to flow from the anode assembly to the cathode assembly; the surface of the cathode assembly is provided with a first reaction element, whose main function is to reduce the compounds in the water through the first reaction element. In the electrochemical system, the cathode receives electrons, which are used by the first reaction element to drive the reduction reaction. For example, for nitrate nitrogen in water , the first reaction piece can reduce it to nitrogen or other harmless nitrogen compounds, thereby achieving the removal of nitrogen pollutants in the water body. A second reaction part is provided on the surface of the anode assembly, and its main function is to oxidize the compounds in the water body through the second reaction part. In the electrochemical system, the anode releases electrons, and the loss of these electrons makes the anode surface positively charged, thereby attracting reducing substances in the water body to the anode. Under the action of the anode surface, the second reaction part can oxidize and decompose reducing substances (such as organic pollutants) in the water body, and convert them into harmless substances such as carbon dioxide and water, thereby achieving the purpose of purifying water quality, improving the problem of poor adaptability of existing denitrification devices, and improving denitrification efficiency. It is especially suitable for rapid denitrification treatment of agricultural groundwater, and has good application prospects and environmental benefits. 2. The cathode assembly and the anode assembly are of the same length and are coaxially arranged, which can ensure that the two have a symmetrical electric field distribution during the electrochemical reaction. This symmetry is conducive to the uniform transmission of electrons and the uniform contact of reactants, thereby improving the overall reaction efficiency of the system; the longer electrode length can significantly increase the contact area between the cathode and anode and the water body. Within the length range of 4m to 8m, the cathode and anode can more fully contact the compounds in the water body, thereby increasing the rate of reduction and oxidation reactions; the longer electrode length can treat a larger volume of water and is suitable for large-scale agricultural groundwater denitrification. This design enables the system to efficiently treat high-flow groundwater and meet the large-scale treatment needs in practical applications; by increasing the electrode length, the cathode and anode can more effectively contact the pollutants in the water body, thereby increasing the rate of reduction and oxidation reactions. The longer electrode length can ensure that more microbial membranes are in contact with pollutants, further improving the denitrification efficiency; and, since groundwater is often 6 meters underground and the groundwater depth in different regions is different, the length of the anode and cathode assemblies is preferably 4 to 8 meters; 3. Microbial membranes are cultivated on both the cathode and anode surfaces, enabling simultaneous reduction and oxidation reactions. The cathode membrane uses electrons to reduce nitrate or nitrite nitrogen, while the anode membrane uses oxidation to treat ammonia or other organic pollutants, achieving efficient denitrification. The membranes efficiently utilize electrons provided by the electrodes or act as electron donors in the reaction, significantly improving reaction rate and denitrification efficiency. Compared to traditional chemical denitrification methods, this reduces reaction time and energy consumption. Installing a dual-electrode denitrification system in a groundwater well directly treats groundwater without pumping it out of the ground, reducing energy consumption and the risk of secondary contamination during treatment. This also lowers system operating costs. The system can be adjusted based on groundwater quality and quantity, making it suitable for treating groundwater in different regions and with varying degrees of contamination, demonstrating its wide applicability. The system boasts a simple design and straightforward installation process: simply follow the steps to drill the well, cultivate the membrane, install the system, fill the reaction medium, and apply voltage. During operation, efficient denitrification is achieved by controlling the power supply voltage, making it easy to operate and suitable for widespread application in agricultural areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the perspective structure of the dual-electrode denitrification system in the embodiment of the present application.

[0027] Figure 2 1 is a top view of the dual-electrode denitrification system in an embodiment of the present application.

[0028] Figure 3 This is a response diagram of the current density corresponding to the change of nitrogen in water in this application.

[0029] Explanation of the accompanying symbols: 1. Data acquisition module; 2. Wire; 3. Power supply; 4. Cathode assembly; 5. Anode assembly; 6. Reaction medium; 7. Aeration plate. DETAILED DESCRIPTION

[0030] The following is combined with Figure 1-3 This application is described in further detail.

[0031] The present application discloses a dual-electrode denitrification system. Figure 1 The dual-electrode denitrification system includes a power supply 3, a cathode assembly 4, an anode assembly 5, an aeration plate 7 and a reaction medium 6.

[0032] Please refer to Figure 1 and Figure 2 In the embodiment of the present application, the power supply 3 is set to direct current, and is electrically connected to the cathode assembly 4 and the anode assembly 5 through the wire 2, respectively, for providing a positive potential to the anode assembly 5, so that electrons flow from the cathode assembly 4 to the anode assembly 5. A first reaction part is provided on the surface of the cathode assembly 4. After the cathode assembly 4 is powered on, a reduction reaction of the compounds in the water body is performed through the first reaction part. A second reaction part is provided on the surface of the anode assembly 5, which is used to perform an oxidation reaction on the compounds in the water body through the second reaction part; the power supply 3 is electrically connected to the cathode assembly 4 and the anode assembly 5, and provides a positive potential to the anode assembly 5, thereby forming an electric potential difference, so that electrons can flow from the anode assembly 5 to the cathode assembly 4; a first reaction part is provided on the surface of the cathode assembly 4, and its main function is to perform a reduction reaction on the compounds in the water body through the first reaction part. In the electrochemical system, the cathode receives electrons, and these electrons are used by the first reaction part to drive the reduction reaction. For example, for nitrate nitrogen in the water body , the first reaction piece can reduce it to nitrogen Or other harmless nitrogen compounds, thereby achieving the removal of nitrogen pollutants in the water body, a second reaction part is provided on the surface of the anode assembly 5, and its main function is to carry out an oxidation reaction on the compounds in the water body through the second reaction part. In the electrochemical system, the anode releases electrons, and the loss of these electrons makes the anode surface positively charged, thereby attracting reducing substances in the water body to the anode. Under the action of the anode surface, the second reaction part can oxidize and decompose reducing substances (such as organic pollutants) in the water body, and convert them into harmless substances such as carbon dioxide and water, thereby achieving the purpose of purifying water quality, improving the problem of poor adaptability of existing denitrification devices, and improving denitrification efficiency. It is particularly suitable for rapid denitrification treatment of agricultural groundwater, and has good application prospects and environmental benefits.

[0033] Specifically, the anode assembly 5 is cylindrical and has a plurality of meshes, which are one or more titanium electrodes. The cathode assembly 4 is cylindrical and is arranged in the anode assembly 5 and coaxially with the anode assembly 5. The cathode assembly 4 is a combination of one or more carbon materials, metal materials, and conductive polymers. The cylindrical structure of the anode assembly 5 can increase the contact area with the electrolyte, thereby improving the electron transfer efficiency and enhancing the denitrification capacity of the system. The metal electrode has good hardness and conductivity. The hard mesh structure surrounding the cathode assembly 4 can prevent the external filler from damaging the internal cathode assembly 4 under the action of water. The cathode assembly 4 is cylindrical and coaxially with the anode assembly 5. The arrangement can ensure that the distance between the cathode assembly 4 and the anode assembly 5 is uniform and fixed, forming a stable electric field distribution, which is conducive to the smooth flow of electrons from the cathode assembly 4 to the anode assembly 5, ensuring the efficient progress of the reduction reaction; at the same time, the cylindrical structure of the cathode assembly 4 can maximize the contact area with the compound, increase the reaction rate, and further improve the denitrification efficiency of the system. The combination of one or more combinations of carbon materials, metal materials, and conductive polymers can not only improve the denitrification efficiency, but also enhance the stability and adaptability of the system; and the mesh structure of the anode assembly 5 surrounding the cathode assembly 4 can prevent hydraulic action from damaging the internal cathode assembly 4.

[0034] It should be noted that in the embodiment of the present application, the diameter of the anode assembly 5 is 28cm~52cm, the diameter of the cathode assembly 4 is 8cm~32cm, and the length of the cathode assembly 4 and the anode assembly 5 is the same, which is 4m~8m; by setting the diameter of the anode assembly 5, the spacing between the anode assembly 5 and the cathode assembly 4 can be ensured, the internal resistance of the intermediate water is avoided to be too large, and the strength of the electrode electric field formed is ensured, thereby stably generating effective current data. If the width of the cathode assembly 4 is too small, the position where microorganisms can attach is too small, which will affect the denitrification effect; and if the width is too large, the current generated is too large, which is easy to affect the current data and cause data changes. Therefore, the width of the cathode assembly 4 is preferably 10~30cm; setting the diameter of the cathode assembly 4 within the range of 8cm to 32cm can ensure that a suitable electrode spacing is formed between the cathode assembly 4 and the anode assembly 5, thereby generating a stable current density and electric field distribution between the two. The cathode assembly 4 and the anode assembly 5 are the same length and are coaxially arranged, which can ensure that the two have a symmetrical electric field distribution during the electrochemical reaction. This symmetry is conducive to the uniform transmission of electrons and uniform contact of reactants, thereby improving the overall reaction efficiency of the system; the longer electrode length can significantly increase the contact area between the cathode and anode and the water body.

[0035] Specifically, within a length range of 4m to 8m, the cathode and anode can more fully contact the ammonia nitrogen and / or nitrate nitrogen in the water body, thereby increasing the rate of reduction and oxidation reactions; longer electrode lengths can treat larger volumes of water and are suitable for large-scale agricultural groundwater denitrification. This design enables the system to efficiently treat high-flow groundwater, meeting the large-scale treatment needs in practical applications; by increasing the electrode length, the cathode and anode can more effectively contact the pollutants in the water body, thereby increasing the rate of reduction and oxidation reactions. A longer electrode length can ensure that more microbial membranes come into contact with the pollutants, further improving denitrification efficiency; and, since groundwater is often 6 meters underground and the depth of groundwater in different regions is different, the length of the anode and cathode assembly 5 is preferably 4 to 8 meters.

[0036] In the embodiment of the present application, the first reaction element and the second reaction element are both microbial membranes, which are cultured in situ on the surface of the cathode assembly 4 and the anode assembly 5. The first reaction element (reducing microbial membrane) on the surface of the cathode assembly 4 can efficiently use the electrons provided by the cathode to reduce compounds in the water (such as nitrate nitrogen) through in situ culture. The microorganisms in these microbial membranes can directly or indirectly use the electrode electrons to transfer them to the nitrate nitrogen. or nitrite nitrogen , which is reduced to nitrogen or other harmless nitrogen compounds; the second reaction element (microbial membrane) on the surface of the anode assembly 5 can oxidize the compounds in the water through in-situ cultivation; the in-situ cultured microbial membrane is tightly combined with the cathode surface, which improves the efficiency of electron transfer and enhances the stability of the microbial membrane during the reaction. In addition, this biocatalytic method can be carried out under mild conditions, avoiding the high energy consumption and secondary pollution problems that may be caused by traditional chemical reduction methods; on the anode surface, the microorganisms in the microbial membrane can reduce organic matter or ammonia nitrogen in the water. As an electron donor, it oxidizes and transfers electrons to the anode to generate current. As an electron donor, it is oxidized to or other oxidized substances; the microbial membranes on the cathode assembly 4 and anode assembly 5 achieve synergistic denitrification of compounds in the water through electron transfer in the electrochemical system. The oxidation reaction at the anode and the reduction reaction at the cathode work together to more efficiently remove nitrogen pollutants from the water.

[0037] For example, the first reaction element is a denitrifying bacteria microbial membrane, the second reaction element is an alcaligenes microbial membrane, and the cultivation method of the first reaction element is as follows: ① Select the anode assembly 5 and the cathode assembly 4, the cathode electrode is used as the working electrode, the anode electrode is used as the counter electrode, and a DC voltage of -0.3~0.5V is applied.

[0038] ② Pass the microbial culture solution into ① and inoculate electroactive microorganisms. The electroactive microorganisms are preferably one or more of Geobacter and Shewanella, and run stably for 3 to 7 days.

[0039] The microorganisms on the surface of the electrode are preferably one or more of Bacillus and Shewanella. These two strains have strong natural adaptability, good current output performance and the most stable operating effect.

[0040] ③ Adjust the voltage to -0.2~0V and run stably for 0.5~1 day.

[0041] ④ Adjust the voltage to -0.6~-0.4V and run stably for 0.5~1 day.

[0042] ⑤ Repeat step ③ until the current fluctuation in step ④ is less than 20%, and the first reaction element is considered to be cultured.

[0043] The microbial biofilm cultivation method described in steps ③ and ④ involves periodic polarity reversal, enabling rapid growth of an electroactive biofilm while also possessing a certain degree of processing power for recalcitrant organic pollutants. Subsequent current fluctuations of less than 20% indicate a stable current flow, indicating completion of the first reaction element cultivation.

[0044] Because Alcaligenes is widely present in aquatic environments and readily available, and studies have shown that this bacteria can directly oxidize ammonia under conditions of electrode polarization and aeration, it is preferable to add Alcaligenes to the anode. Since the cathode primarily reduces nitrate nitrogen, adding denitrifying bacteria facilitates biological denitrification. Applying a voltage of 0.1-0.5V can promote ammonia oxidation and increase the rate of groundwater denitrification.

[0045] like Figure 1 As shown, in the embodiment of the present application, since direct ammonia oxidation using Alcaligenes requires ventilation to maintain the metabolic activity of Alcaligenes, and the aeration bubble diameter of the aeration disk 7 is small, the gas-liquid interface area is large, the bubble diffusion is uniform, the corrosion resistance is strong, and the oxygen utilization rate is high, the aeration disk 7 is preferably used as the aeration device, and the aeration disk 7 is arranged at one end of the anode assembly 5 and is fixedly connected to the anode assembly 5.

[0046] Specifically, the aeration plate 7 is provided at the bottom of the anode assembly 5. The main function of the aeration plate 7 is to provide oxygen to the system. During the oxidation reaction of the anode assembly 5, oxygen can act as an electron acceptor and participate in the oxidation reaction, thereby promoting the metabolic activity of the second reaction component on the anode surface. For example, in the oxidation of ammonia nitrogen at the anode During this process, oxygen can accept electrons, producing water or other harmless substances, thereby driving the oxidation reaction. The aeration disc 7 introduces air into the system, enhancing water mixing and mass transfer. The rising bubbles agitate the water, allowing pollutants (such as ammonia nitrogen and nitrate nitrogen) in the water to fully contact the reactants on the electrode surface, thereby increasing the reaction rate. The oxygen provided by the aeration disc 7 maintains the activity of the second reactant in the anode assembly 5. Microorganisms in the second reactant require oxygen for aerobic respiration to maintain normal metabolic activity. The continuous supply of oxygen from the aeration disc 7 ensures that the second reactant remains highly active during the oxidation reaction, thereby improving the system's denitrification efficiency.

[0047] like Figure 2 As shown, reaction medium 6 is disposed within cathode assembly 4 and between anode assembly 5 and cathode assembly 4. Reaction medium 6 is used to provide the necessary ionic environment for the electrochemical reactions in anode assembly 5 and cathode assembly 4, ensuring the transfer of electrons and protons. By providing the necessary ionic environment and enhancing conductivity, reaction medium 6 can significantly increase the electrochemical reaction rates at the anode and cathode, thereby improving the system's denitrification efficiency. For example, during the oxidation of ammonia nitrogen at the anode and the reduction of nitrate nitrogen at the cathode, the ions in reaction medium 6 can accelerate the transfer of electrons and protons, increasing the reaction rate. Reaction medium 6 also ensures charge balance and pH stability in the system, thereby optimizing the system's overall performance. A stable charge balance and pH environment contribute to the long-term stable operation of the microbial membrane and reduce fluctuations in microbial activity.

[0048] Furthermore, the use of reaction medium 6 can reduce the system's need for external chemical reagents, such as the use of added acids, bases, or buffers. The buffering effect of reaction medium 6 itself can maintain a stable pH in the system, thereby reducing operating costs. Reaction medium 6 can also buffer acid-base fluctuations during the reaction, reducing the impact of pH fluctuations on the microbial membrane, thereby improving system stability. Furthermore, the ions in reaction medium 6 can neutralize the charge generated on the electrode surface, reducing electrode polarization and further improving system stability.

[0049] Exemplary method for preparing the reaction medium 6 filled in the middle of the dual-electrode denitrification system: ① Screening biochar materials prepared from waste organic matter, including but not limited to one or more of residual sludge, discarded tires, straw, feces, and food waste. Waste organic matter is abundant and contains a large amount of hydrocarbon-containing organic matter, making it a potential resource. Therefore, it is used as a raw material for biochar.

[0050] ② Press the waste organic matter used to prepare biochar into a ball, or press it into shape using a mold.

[0051] ③ Place the formed raw materials in a tube furnace and calcine them at high temperature under a nitrogen atmosphere. The calcination temperature is 300~700 degrees Celsius and the calcination time is 10~80 minutes.

[0052] The calcination temperature and time should not be too low or too short, which will result in poor performance of the biochar material, nor should they be too high or too long, which will result in energy waste.

[0053] ④ Cooling in an oxygen-free environment to obtain the reaction medium 6 filled in the middle of the dual-electrode denitrification system.

[0054] It should be noted that one or more dual-electrode denitrification systems can be set up according to the size of the contaminated site to be repaired, and placed perpendicular to the direction of the underground pollution plume. Since the effective range radius of a single dual-electrode denitrification system is generally 0.5~2 meters, the layout spacing is preferably 1~4 meters; by constructing a cathode biofilm that can be quickly started on the first reaction element, ammonia nitrogen in groundwater is removed by two ways: anodic oxidation of ammonia nitrogen and then reduction to nitrogen gas through the cathode, and anodic oxidation of ammonia nitrogen and final reduction to nitrogen gas. Ammonium nitrogen in groundwater is removed by cathode reduction of nitrate nitrogen and final nitrogen gas, thereby constructing a dual-electrode denitrification system.

[0055] Illustratively, in another embodiment of the present application, the dual-electrode denitrification system is further provided with a data acquisition module 1, which is electrically connected to the anode assembly 5 and the power supply 3 through a wire 2, and the data acquisition module 1 is configured to collect the current current conditions and send display instructions to the terminal; the terminal includes but is not limited to devices such as a display or a mobile phone.

[0056] Specifically, the dual-electrode denitrification system simulates a permeable reaction wall placed in the underground aquifer, adds biochar materials made from burning waste, and monitors the changes in ammonia nitrogen and nitrate nitrogen in the groundwater in real time through changes in current.

[0057] The present application also discloses a rapid denitrification technology for agricultural groundwater, comprising the following steps: S1, drilling wells according to actual needs and the established specifications of the dual electrode denitrification system.

[0058] In this step, by determining the actual groundwater area that needs to be repaired, formulating the specifications of the dual-electrode denitrification system, and drilling wells according to the specifications and quantity of the required dual-electrode denitrification system, it can be ensured that the size of the well is perfectly matched with the system, providing a basic guarantee for the subsequent installation and stable operation of the system. In combination with actual needs, comprehensive consideration of factors such as groundwater level, water quality, water volume and surrounding geological conditions, the depth and diameter of the well can be flexibly adjusted to enable the system to better adapt to the groundwater environment in different regions and improve its applicability in different scenarios; the well can provide stable support for the dual-electrode denitrification system, avoiding problems such as loose installation and tilting of the system due to inappropriate well size, thereby ensuring the stability of the system during operation. The well depth and diameter are conducive to sufficient contact and exchange between groundwater and the system, providing good hydraulic conditions for the denitrification reaction, thereby improving the denitrification efficiency.

[0059] S2, culturing the first reaction element and the second reaction element on the surfaces of the anode assembly 5 and the cathode assembly 4.

[0060] In this step, a dual-electrode denitrification system can be built, the anode component 5 is surrounded by the outer layer of the cathode component 4, and the aeration plate 7 and the power supply 3 are installed; the microbial membrane has efficient biocatalytic ability, can use the electrons provided by the electrode or act as an electron donor to participate in the reaction, accelerate the denitrification reaction, and significantly improve the denitrification efficiency. Compared with traditional chemical denitrification methods, it reduces reaction time and energy consumption. The biocatalytic effect of the microbial membrane is a natural and green treatment method that does not produce harmful chemical by-products, avoids the secondary pollution problem that may be caused by traditional chemical denitrification methods, and meets the requirements of sustainable development. The microbial membrane has the ability of self-regulation and self-repair, and can automatically adjust its metabolic activity and growth state according to changes in environmental conditions, thereby maintaining efficient and stable performance in long-term operation and reducing manual maintenance costs and workload.

[0061] The cultivation of the first reaction element and the second reaction element enables the formation of an efficient biocatalytic layer on the surface of the anode and cathode components 4, which can quickly convert ammonia nitrogen and / or nitrate nitrogen in the groundwater into harmless substances such as nitrogen gas, thereby achieving the purpose of rapid denitrification. The microbial film can ensure that the reaction on the electrode surface continues, reduce problems such as decreased denitrification efficiency due to fluctuations in microbial activity or shedding, and improve the long-term operating stability of the system.

[0062] S3, placing the dual-electrode denitrification system into the well, and connecting the power supply 3 and the dual-electrode denitrification system.

[0063] In this step, the operation process of placing the system into the well and connecting the power supply 3 is simple and easy, without the need for complex equipment and cumbersome steps, which lowers the technical threshold and facilitates promotion and application in agricultural areas. The dual-electrode denitrification system is installed in the well as a whole, realizing the integration of the equipment, reducing the connection and assembly links between the equipment, and improving the integrity and reliability of the system; connecting the power supply 3 ensures that the system can start and operate normally, provides power support for subsequent denitrification reactions, and enables the system to operate according to a predetermined process flow. After connecting the power supply 3, an electric potential difference is formed between the anode assembly 5 and the cathode assembly 4, and electrons flow from the anode to the cathode, driving the oxidation reaction of the anode and the reduction reaction of the cathode, thereby realizing electrochemical denitrification treatment of groundwater.

[0064] S4, filling the reaction medium 6, and applying voltage to the anode.

[0065] Exemplarily, in this step, the voltage applied to the anode is -0.3~0.5V; the reaction medium 6 can provide the necessary ionic environment for the electrochemical reaction, increase the electrical conductivity of the water body, reduce the resistance between the electrodes, ensure the efficient transfer of electrons and protons, and thus increase the rate of the electrochemical reaction. The ions in the reaction medium 6 can neutralize the charge generated on the electrode surface, maintain the charge balance of the system, avoid electrode polarization caused by charge accumulation, and ensure the stability of the electrode and the continuous progress of the reaction. The reaction medium 6 can buffer the acid-base changes generated during the reaction process, maintain the relative stability of the system pH, and provide good conditions for the activity of the microbial membrane and the stability of the electrochemical reaction. After filling the reaction medium 6, the system can better carry out the electrochemical reaction, improve the denitrification efficiency and reaction rate, and reduce the loss and maintenance cost of the electrode.

[0066] Specifically, both the cathode assembly 4 and the anode assembly 5 are cultured with a first and second reactant, capable of simultaneous reduction and oxidation reactions. The cathode microbial membrane uses electrons to reduce nitrate or nitrite nitrogen, while the anode microbial membrane treats ammonia nitrogen or other organic pollutants through oxidation, achieving efficient denitrification. The first and second reactants can efficiently utilize electrons provided by the electrodes or act as electron donors in the reaction, significantly improving the reaction rate and denitrification efficiency. Compared to traditional chemical denitrification methods, this reduces reaction time and energy consumption. Installing a dual-electrode denitrification system in a groundwater well directly treats groundwater without pumping it out of the ground, reducing energy consumption and the risk of secondary contamination during the treatment process. This also lowers the system's operating costs. The system can be adjusted based on groundwater quality and quantity, making it suitable for treating groundwater in different regions and with varying degrees of contamination, thus offering wide applicability. The entire system features a simple design and easy installation process: simply follow the steps of drilling a well, cultivating the microbial membrane, installing the system, filling the reaction medium 6, and applying voltage. During system operation, efficient denitrification is achieved by controlling the voltage of the power supply 3. This simple operation makes it suitable for widespread application in agricultural areas.

[0067] For example, in another embodiment of the present application, the following steps are further included: S5 , setting data sampling points and data acquisition module 1 , and acquiring current data through data acquisition module 1 .

[0068] In this step, the data acquisition module 1 is electrically connected to the anode assembly 5 and the power supply 3 through the wire 2. The data acquisition module 1 is configured to collect the current current conditions and send display instructions to the terminal, so as to monitor the nitrogen conditions in different groundwater layers.

[0069] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A dual-electrode denitrification system, characterized in that: include: A cathode assembly (4) is provided with a first reaction element on its surface, and is used to perform a reduction reaction on compounds in the water body through the first reaction element; An anode assembly (5) is provided with a second reaction element on its surface, and is used to perform an oxidation reaction on compounds in the water body through the second reaction element; The power supply (3) is electrically connected to the cathode assembly (4) and the anode assembly (5) respectively, and is used to provide a positive potential to the anode assembly (5) so that electrons flow from the cathode assembly (4) to the anode assembly (5).

2. The dual-electrode denitrification system according to claim 1, characterized in that: The anode assembly (5) is cylindrical and provided with a plurality of meshes, and is one or more types of titanium electrodes.

3. The dual-electrode denitrification system according to claim 2, characterized in that: The diameter of the anode assembly (5) is 28 cm to 52 cm.

4. The dual-electrode denitrification system according to claim 1, characterized in that: The cathode assembly (4) is cylindrical and is arranged inside the anode assembly (5) and coaxially arranged with the anode assembly (5). The cathode assembly (4) is a combination of one or more carbon materials, metal materials, and conductive polymers.

5. The dual-electrode denitrification system according to claim 4, characterized in that: The diameter of the cathode assembly (4) is 8 cm to 32 cm.

6. The dual-electrode denitrification system according to claim 1, characterized in that: The first reaction member and the second reaction member are both microbial membranes, and the first reaction member and the second reaction member are cultured in situ on the surfaces of the cathode assembly (4) and the anode assembly (5).

7. The dual-electrode denitrification system according to claim 1, characterized in that: The cathode assembly (4) and the anode assembly (5) have the same length, which is 4m to 8m.

8. The dual-electrode denitrification system according to claim 1, characterized in that: It also includes an aeration plate (7), which is arranged at one end of the anode assembly (5) and is fixedly connected to the anode assembly (5).

9. The dual-electrode denitrification system according to claim 1, characterized in that: The invention also includes a reaction medium (6), which is arranged in the cathode assembly (4) and between the anode assembly (5) and the cathode assembly (4). The reaction medium (6) is used to provide a necessary ion environment for the electrochemical reaction of the anode assembly (5) and the cathode assembly (4) to ensure the transfer of electrons and protons.

10. A rapid denitrification technology for agricultural groundwater, using the dual-electrode denitrification system according to any one of claims 1 to 9, characterized in that: The steps include: Drill wells according to actual needs and the established specifications of the dual-electrode denitrification system; Cultivating a first reaction element and a second reaction element on the surfaces of the anode component (5) and the cathode component (4); Place the dual-electrode denitrification system in the well, and connect the power supply (3) and the dual-electrode denitrification system; The reaction medium (6) is filled and a voltage is applied to the anode.

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