An electrochemical wastewater treatment device and method based on electron mediator-mediated EPD-Anammox system

Abstract

The present application relates to an EPD-Anammox system electrochemical wastewater treatment device and method based on electron mediator mediation, which solves the core pain points of the traditional anaerobic ammonia oxidation process, such as lack of phosphorus removal capacity, easy inhibition of bacterial flora, low efficiency of electron utilization, poor impact resistance, etc. Through the zinc anode electrochemical reaction mediated by the electron mediator, the process coupling of electrochemistry and EPD-Anammox process is opened up, realizing precise electron transfer, optimization of bacterial flora structure and chemical-biological synergistic phosphorus removal. While improving the efficiency of denitrification and phosphorus removal, the long-term operation stability of the system is optimized, and the energy consumption and chemical consumption are reduced. It is a great innovation in wastewater treatment device and method, and has significant economic and environmental benefits.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an electrochemical wastewater treatment device and method based on an EPD-Anammox system mediated by electronic mesones. Background Technology

[0002] The EPD-Anammox process has significant advantages in energy saving and consumption reduction, but its engineering application still faces many challenges: the slow proliferation of anaerobic ammonia-oxidizing bacteria AnAOB leads to a long system start-up cycle, and it is sensitive to water quality conditions such as temperature and pH, resulting in poor operational stability; at the same time, this process is highly dependent on stable nitrite NO2. - -N supply is crucial, and achieving a highly efficient and stable enhanced partial denitrification (EPD) process is key. Furthermore, competition for organic carbon sources and electron acceptors exists among denitrifying phosphorus-accumulating bacteria (DPAOs), glycogenotrophic bacteria (DGAOs), and AnAOBs in the system, making it difficult to coordinate the optimal sludge age (SRT). Therefore, it is imperative to invent a wastewater treatment method that achieves precise electron transfer, optimized microbial community structure, and synergistic chemical-biological phosphorus removal, thereby significantly improving the system's nitrogen and phosphorus removal efficiency and operational stability. Summary of the Invention

[0003] In view of the above situation and to overcome the shortcomings of the existing technology, the purpose of this invention is to provide an electrochemical wastewater treatment device and method based on an EPD-Anammox system mediated by electronic mediators. This invention couples electrochemical technology with the EPD-Anammox process, and through the electrochemical reaction of the zinc anode mediated by electronic mediators, achieves precise electron transfer, optimization of microbial community structure, and synergistic chemical-biological phosphorus removal, thereby significantly improving the system's nitrogen and phosphorus removal efficiency and operational stability.

[0004] The technical solution provided by this invention is an electrochemical wastewater treatment method based on an EPD-Anammox system mediated by electronic mediators. This method utilizes an EPD-Anammox system electrochemical wastewater treatment device mediated by electronic mediators, and then proceeds according to the following steps:

[0005] 1) EPD reaction stage: Influent I, rich in organic matter, from the first storage tank is pumped into the EPD reactor via the first influent pump, while the agitator is turned on and anaerobic stirring is performed for 1.5-2 hours; subsequently, influent I, rich in NO3, from the second storage tank... - -N and PO4 3--P's influent II is pumped into the EPD reactor through the second influent pump. Simultaneously, the solution containing electron mediators in the storage tank is added to the EPD reactor through the first wastewater pump, and the electrochemical device is turned on to react for 5-10 minutes. After 35-45 minutes of anoxic stirring, the stirrer is stopped, and sedimentation is allowed for 35-50 minutes. After sedimentation, the aeration pump is turned on to aerate for 30-40 minutes, and after the aeration pump is turned off, the mixture is allowed to stand for 1-2 hours. The EPD effluent is temporarily stored in the third storage tank through the drain valve.

[0006] 2) Anammox reaction stage: The EPD effluent from the third water tank and the sewage from the fourth water tank are fed into the Anammox reactor through the second sewage pump and the third sewage pump, respectively, while the circulation pump is turned on to carry out the reaction.

[0007] Preferably, in step 1), influent I uses sodium acetate as the carbon source, has a COD of 313±15 mg / L, an influent time of 20 min, and an influent volume of 4.5 L; influent II uses sodium nitrate and dipotassium hydrogen phosphate as the nitrogen and phosphorus sources, respectively, and NO3-... - -N concentration was 70±5 mg / L, PO4 3- -P concentration is 10±5mg / L, influent time is 5min, influent volume is 0.5-1.0L; effluent ratio is 50-60%.

[0008] Preferably, in step 1), the electrochemical device consists of an EPD electrode device and an Anammox electrode device. Within the EPD system: the EPD electrode device consists of three zinc anodes and three graphite cathodes arranged in a staggered pattern on the inner wall of the EPD reactor, connected to a DC power supply via wires; the EPD electrode device is activated synchronously when influent II enters, with a current density of 1.5-2.5 mA / cm² and an energizing time of 5-10 min. Within the Anammox system: the Anammox electrode device consists of one zinc anode and one graphite cathode arranged on the inner wall of the Anammox reactor, connected to a DC power supply via wires; the Anammox electrode device is activated synchronously with the entry of EPD influent II, with a current density of 1.5-2.5 mA / cm² and an energizing time of 5-10 min.

[0009] Preferably, in step 1), the solution containing the electron meson is 2-hydroxy-1,4-naphthoquinone (HNQ), with a dosage concentration of 1.5–2.0 mg / L, and is added to the anoxic section of the EPD system. The addition frequency is once every 3 days, and it is added synchronously with the influent II. The residual electron meson 2-hydroxy-1,4-naphthoquinone (HNQ) and its intermediate are introduced into the Anammox reactor along with the EPD effluent.

[0010] Preferably, in step 2), ammonium chloride is added to the Anammox reactor feedwater as NH4. ＋ -N source, NH4＋ -N is 35-40 mg / L, and the EPD effluent contains NO2. - -N source, NO2 - -N is 45.5-52 mg / L, and any deficiency should be supplemented manually. The water retention time should be controlled at 8-10 hours, and the circulation pump should circulate at 200-300%.

[0011] The EPD-Anammox system electrochemical wastewater treatment device based on electronic mediators includes an EPD reactor, a water storage tank, an aeration pump, an electrochemical device, and an Anammox reactor. The first water storage tank is connected to the EPD reactor via a first inlet pump, and the second water storage tank is connected to the EPD reactor via a second inlet pump. The aeration pump is connected to the bottom of the EPD reactor for aeration and oxygen supply. The electrochemical device is connected to the EPD reactor and the Anammox reactor via pipelines. The EPD reactor is equipped with a stirrer. The liquid storage tank is connected to the EPD reactor via a first wastewater pump, and the third water storage tank is connected to the EPD reactor. The third and fourth water storage tanks are connected to the Anammox reactor via the second and third wastewater pumps, respectively.

[0012] Preferably, the Anammox reactor is equipped with a circulation pump, a gas generation circulation pipe, and an Anammox electrode device. The circulation pump and the gas generation circulation pipe are both connected to the water outlet at the bottom of the Anammox reactor to realize gas circulation and water circulation respectively, thereby improving the mud-water mixing and reaction rate in the Anammox reactor.

[0013] Preferably, the EPD electrode device consists of three first Zn anodes and three first graphite cathodes fixed to the first conductor by a first binding rib. The Zn anodes are φ8×100mm in size, and the graphite cathodes are φ8×100mm in size.

[0014] Preferably, the Anammox electrode device consists of a second Zn anode and a second graphite cathode, which are fixed to a second conductor by a second binding rib. The Zn anode has a size of φ8×100mm, and the graphite cathode has a size of φ8×100mm.

[0015] Preferably, the first and second inlet pumps are PVDF magnetic circulation pumps.

[0016] Preferably, the first sewage pump, the second sewage pump, and the third sewage pump are WQ / QW type submersible sewage pumps.

[0017] Preferably, a drain valve 6-2 is installed on the pipeline connecting the third water storage tank 8 and the EPD reactor 1, and the EPD electrode device 1-2 is located above the drain valve, so that the electrode device is only immersed in sewage during operation, preventing excessive corrosion of the electrode due to long-term immersion and the release of excessive metal ions that may affect the operation of EPD.

[0018] Preferably, the Anammox reactor 7 is provided with a granular sludge zone 7-2-5, a mixing zone 7-2-6 and a sludge-water separation zone 7-2-7 arranged sequentially from bottom to top, and the Anammox electrode device 7-2 is located in the mixing zone 7-2-6.

[0019] This invention establishes a process coupling between electrochemistry and the EPD-Anammox process by using electron mediators to mediate the electrochemical reaction at the zinc anode. This solves the core problems of traditional anaerobic ammonia oxidation processes, such as lack of phosphorus removal capacity, easy inhibition of microbial communities, low electron utilization efficiency, and poor shock resistance. While improving the efficiency of nitrogen and phosphorus removal, it also optimizes the long-term operational stability of the system and reduces energy and reagent consumption, resulting in significant economic and environmental benefits. Attached Figure Description

[0020] Figure 1 This is a structural connection block diagram of the present invention.

[0021] Figure 2 This is a schematic diagram of the EPD reactor structure of the present invention.

[0022] Figure 3 This is a schematic diagram of the Anammox reactor structure of the present invention.

[0023] In the diagram, the components are: EPD reactor 1, stirrer 1-1, EPD electrode device 1-2, first Zn anode 1-2-1, first graphite cathode 1-2-2, first binding rib 1-2-3, first wire 1-2-4, first water storage tank 2, first inlet pump 2-1, second water storage tank 3, second inlet pump 3-1, aeration pump 4, electrochemical device 5, liquid storage tank 6, first sewage pump 6-1, drain valve 6-2, Anammox reactor 7, circulation pump 7-1, Anammox electrode device 7-2, second Zn anode 7-2-1, second graphite cathode 7-2-2, second binding rib 7-2-3, second wire 7-2-4, granular sludge zone 7-2-5, mixing zone 7-2-6, sludge-water separation zone 7-2-7, third water storage tank 8, second sewage pump 8-1, fourth water storage tank 9, third sewage pump 9-1, and gas generation circulation pipe 10. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0025] Depend on Figure 1The present invention provides an electrochemical wastewater treatment method based on an EPD-Anammox system mediated by electronic messons, which utilizes an EPD-Anammox system electrochemical wastewater treatment device based on electronic messons, and then proceeds according to the following steps:

[0026] 1) EPD reaction stage: The organic-rich influent I from the first water storage tank 2 is pumped into the EPD reactor 1 through the first influent pump 2-1, while the stirrer 1-1 is turned on and anaerobic stirring is carried out for 1.5-2 hours; then the NO3-rich in the second water storage tank 3 is pumped into the reactor. - -N and PO4 3- -P's influent II is pumped into EPD reactor 1 through the second influent pump 3-1. Simultaneously, the solution containing electron mediators in storage tank 6 is added to EPD reactor 1 through the first wastewater pump 6-1, and the electrochemical device 5 is turned on to react for 5-10 minutes. After 35-45 minutes of anoxic stirring, stirrer 1-1 is stopped, and sedimentation takes place for 30-40 minutes. After sedimentation, aeration pump 4 is turned on to aerate for 30-40 minutes, and after aeration pump 4 is turned off, the mixture is left to stand for 1-2 hours. The EPD effluent is temporarily stored in the third storage tank 8 through drain valve 6-2.

[0027] 2) Anammox reaction stage: The EPD effluent from the third water tank 8 and the sewage from the fourth water tank 9 are fed into the Anammox reactor 7 through the second sewage pump 8-1 and the third sewage pump 9-1, respectively, while the circulation pump 7-1 is turned on to carry out the reaction.

[0028] Preferably, in step 1), influent I uses sodium acetate as the carbon source, has a COD of 313±15 mg / L, an influent time of 20 min, and an influent volume of 4.5 L; influent II uses sodium nitrate and dipotassium hydrogen phosphate as the nitrogen and phosphorus sources, respectively, and NO3-... - -N concentration was 70±5 mg / L, PO4 3- -P concentration is 10±5mg / L, influent time is 5min, influent volume is 0.5-1.0L; effluent ratio is 50-60%.

[0029] Preferably, in step 1), the electrochemical device 5 consists of an EPD electrode device 1-2 and an Anammox electrode device 7-2. Within the EPD system: the EPD electrode device 1-2 consists of three zinc anodes and three graphite cathodes arranged in a staggered pattern on the inner wall of the EPD reactor, connected to a DC power supply via wires; the EPD electrode device 1-2 is activated synchronously when influent II enters, with a current density of 1.5-2.5 mA / cm² and an energizing time of 5-10 min. Within the Anammox system: the Anammox electrode device 7-2 consists of one zinc anode and one graphite cathode arranged on the inner wall of the Anammox reactor, connected to a DC power supply via wires; the Anammox electrode device 7-2 is activated synchronously with the entry of EPD influent II, with a current density of 1.5-2.5 mA / cm² and an energizing time of 5-10 min.

[0030] Preferably, in step 1), the solution containing the electron meson is 2-hydroxy-1,4-naphthoquinone (HNQ), with a dosage concentration of 1.5–2.0 mg / L, and is added to the anoxic section of the EPD system. The addition frequency is once every 3 days, and it is added synchronously with the influent II. The residual electron meson 2-hydroxy-1,4-naphthoquinone (HNQ) and its intermediate are introduced into the Anammox reactor along with the EPD effluent.

[0031] Preferably, in step 2), ammonium chloride is added to the Anammox reactor feedwater as NH4. ＋ -N source, NH4 ＋ -N is 35-40 mg / L, and the EPD effluent contains NO2. - -N source, NO2 - -N is 45.5-52 mg / L, and any deficiency should be supplemented manually. The water retention time should be controlled at 8-10 hours, and the circulation pump should circulate at 200-300%.

[0032] The electrochemical wastewater treatment device based on the electronically mediated EPD-Anammox system includes an EPD reactor, a water storage tank, an aeration pump 4, an electrochemical device, and an Anammox reactor. The first water storage tank 2 is connected to the EPD reactor 1 via a first inlet pump 2-1, and the second water storage tank 3 is connected to the EPD reactor 1 via a second inlet pump 3-1. The aeration pump 4 is connected to the bottom of the EPD reactor 1 for aeration and oxygen supply. The electrochemical device 5 is connected to the EPD reactor 1 and the Anammox reactor 7 via pipelines. The EPD reactor 1 is equipped with a stirrer 1-1 and an EPD electrode device 1-2. The liquid storage tank 6 is connected to the EPD reactor 1 via a first wastewater pump 6-1. The third water storage tank 8 is connected to the EPD reactor 1. The third water storage tank 8 and the fourth water storage tank 9 are connected to the Anammox reactor 7 via a second wastewater pump 8-1 and a third wastewater pump 9-1, respectively. Preferably, the Anammox reactor 7 is equipped with a circulation pump 7-1, a gas production circulation pipe 10, and an Anammox electrode device 7-2. The circulation pump 7-1 and the gas production circulation pipe 10 are both connected to the water outlet at the bottom of the Anammox reactor 7 to realize gas circulation and water circulation respectively, thereby improving the mud-water mixing and reaction rate in the Anammox reactor 7.

[0033] like Figure 2 As shown, the EPD electrode device 1-2 is composed of three first Zn anodes 1-2-1 and three first graphite cathodes 1-2-2 fixed to the first conductor 1-2-4 by the first binding rib 1-2-3. The Zn anode size is φ8×100mm and the graphite cathode size is φ8×100mm.

[0034] like Figure 3 As shown, the Anammox electrode device 7-2 consists of a second Zn anode 7-2-1 and a second graphite cathode 7-2-2 fixed to a second conductor 7-2-4 by a second binding rib 7-2-3. The Zn anode has a size of φ8×100mm and the graphite cathode has a size of φ8×100mm.

[0035] Preferably, the first inlet pump 2-1 and the second inlet pump 3-1 are PVDF magnetic circulation pumps.

[0036] Preferably, the first sewage pump 6-1, the second sewage pump 8-1, and the third sewage pump 9-1 are WQ / QW type submersible sewage pumps.

[0037] Preferably, a drain valve 6-2 is installed on the pipeline connecting the third water storage tank 8 and the EPD reactor 1, and the EPD electrode device 1-2 is located above the drain valve, so that the electrode device is only immersed in sewage during operation, preventing excessive corrosion of the electrode due to long-term immersion and the release of excessive metal ions that may affect the operation of EPD.

[0038] Preferably, the Anammox reactor 7 is provided with a granular sludge zone 7-2-5, a mixing zone 7-2-6 and a sludge-water separation zone 7-2-7 arranged sequentially from bottom to top, and the Anammox electrode device 7-2 is located in the mixing zone 7-2-6.

[0039] In use, the first water tank 2 supplies water to the EPD reactor 1 via the first inlet pump 2-1 and the second water tank 3 via the second inlet pump 3-1. The aeration pump 4 is connected to the bottom of the EPD reactor 1 for aeration and oxygen supply. The electrochemical device 5 is connected to the EPD reactor 1 via pipeline for electrochemical treatment. The EPD reactor 1 is equipped with a stirrer 1-1 to achieve water mixing. At the same time, the solution containing electron mediators in the liquid storage tank 6 is added to the EPD reactor 1 via the first sewage pump 6-1. The EPD effluent in the third water tank 8 and the sewage in the fourth water tank 9 enter the Anammox reactor 7 via the second sewage pump 8-1 and the third sewage pump 9-1, respectively. At the same time, the circulation pump 7-1 is turned on to carry out the reaction. The Anammox reactor 7 is equipped with the circulation pump 7-1 to achieve internal water circulation. After the system is successfully started, the generated gases such as N2 and CO2 enter the Anammox reactor 7 through the circulation pipe to achieve internal gas circulation.

[0040] The Anammox reactor 7 is equipped with a granular sludge zone 7-2-5, a mixing zone 7-2-6, and a sludge-water separation zone 7-2-7. The granular sludge zone is mainly a rich area for anaerobic ammonia-oxidizing bacteria, the mixing zone is mainly a rich area for heterotrophic bacteria and some anaerobic ammonia-oxidizing bacteria, and the sludge-water separation zone is mainly used to separate sludge and water to prevent the loss of functional bacteria. The gas recirculation pipe 10 and wastewater return from the Anammox reactor are both returned from the sludge-water separation zone 7-2-7 to the granular sludge zone 7-2-5.

[0041] Anammox electrode device 7-2 is located in mixing zone 7-2-6, which is rich in anaerobic ammonia oxidizing bacteria and heterotrophic bacteria. The released metal ions mix with some of the anaerobic ammonia oxidizing bacteria and heterotrophic bacteria. After the wastewater is returned to the granular sludge zone, the activity of anaerobic ammonia oxidizing bacteria and heterotrophic bacteria is improved, thus enhancing the total nitrogen removal rate of the Anammox reactor.

[0042] The EPD electrode device 1-2 is located above the connecting pipe where the drain valve 6-2 is located, so that the electrode device is only immersed in sewage during operation, preventing excessive corrosion of the electrode due to long-term immersion and the release of excessive metal ions, which would affect the operation of EPD.

[0043] Case Study:

[0044] Typical low C / N industrial wastewater contains a large amount of NO3. - -N and NH4 ＋-N was used to construct an electrochemically enhanced EPD-Anammox system mediated by electro-electron mesons. The total HRT of the EPD system was 5 hours, including 120 minutes of anaerobic digestion, 40 minutes of anoxic digestion, 30 minutes of sedimentation, 10 minutes of drainage, 30 minutes of post-aeration, and 70 minutes of settling. After the start of the anaerobic stage, influent I was introduced into the EPD system via an influent pump for 20 minutes. After the start of the anoxic stage, influent II was introduced into the EPD system via an influent pump for 5 minutes. 2-hydroxy-1,4-naphthoquinone electro-mesons were used at a concentration of 2 mg / L and a frequency of 3 days / time. Both the EPD and Anammox systems used Zn as the anode and graphite as the cathode, with a current density of 1.99 mA / cm². The energizing time was synchronized with that of influent II for 5 minutes.

[0045] The effluent from the EPD system is mixed with the raw water and then enters the Anammox system, with the HRT controlled at 8 hours.

[0046]

[0047] The EPD system is enriched with a large number of denitrification genes napA, napB, narG, narZ, and nxrA, as well as genes that promote TCA, glyoxylate, and internal carbon source conversion metabolism, including Thaurea (17.55%), Defluviicoccus (3.15%), Candidatus_Competibacter (6.99%), and Candidatus_Contendobacter (7.30%).

[0048] The Anammox system is enriched with a large number of denitrification genes napA, napB, narI, narV, nirK, nirS and anaerobic ammonia oxidation genes hzsA, hzsB, nrxB, which promote internal carbon source conversion metabolism but inhibit TCA and glyoxylate metabolism. It is enriched with Candidatus_Brocadia 19.04%, Candidatus_Defluviilinea 3.42%, Denitratisoma 5.99%, Rubrivivax 3.16%, and Candidatus_Villigracilis 3.84%.

[0049] After 100 days of operation, the EPD-Anammox system achieved a COD removal rate of up to 78.12%, a total nitrogen removal rate of up to 88.66%, and a total phosphorus removal rate of 40.02%.

[0050] Zn produced by Zn anodic electrolysis in this invention 2＋ With PO4 3--P forms precipitates to achieve chemical phosphorus removal and directionally enriches DGAOs such as Candidatus_Competibacter. Electron mesons synergistically interact with the Zn anode to further enrich DGAOs and DPAOs, enhancing the system's synergistic carbon, nitrogen, and phosphorus removal capabilities. Electron mesons mediate significant upregulation of genes such as napA, napB, narG, narZ, and nxrA in the EPD system through Zn anode, promoting NO2 removal. - -N accumulation; at the same time, the expression of hzs and hdh genes is upregulated in the Anammox system, and AnAOB and heterotrophic denitrifying bacteria are enriched, achieving efficient nitrogen removal through multiple pathways.

[0051] Electron-mediated Zn anode significantly upregulates internal carbon source conversion metabolism in the Anammox system, but inhibits TCA and glyoxylate metabolic pathways; electron-mediated Zn anode significantly upregulates the EPD-Anammox system, and Zn is produced by Zn anode electrolysis. 2 ＋ It can be used with PO4 3- -P forms a complex precipitate, achieving efficient chemical phosphorus removal; electron mediators significantly enhance extracellular electron transfer, increasing the activity of key denitrification enzymes nitrate reductase NR and nitrite reductase NIR in the EPD system, as well as the expression of related functional genes napA, napB, narG, narZ, and nxrA, thus promoting NO3- removal. - -N to NO2 - Efficient conversion and accumulation of -N; synergistic effect of electron mesons and Zn anodes, targeted enrichment of DAGOs and DPAOs such as Candidatus_Competibacter, Thaurea, and Defluviicoccus, enhancing the co-metabolic capacity of carbon, nitrogen, and phosphorus; residual Zn in EPD effluent 2＋ The electron mediators, after preliminary transformation, enter the Anammox system, further increasing the expression levels of the core functional genes hzs and hdh in anaerobic ammonia oxidation, enriching AnAOBs such as Candidatus_Brocadia and Candidatus_Defluviilinea, and simultaneously promoting the growth of heterotrophic denitrifying bacteria such as Denitrosoma, Rubrivivax, and Candidatus_Villigracilis, forming a multi-pathway synergistic nitrogen removal mechanism of Anammox-heterotrophic denitrification, significantly improving the system's nitrogen removal performance and shock resistance.

[0052] This technology has significant advantages:

[0053] ① HNQ-mediated electron shuttle and microbial community regulation

[0054] 2-Hydroxy-1,4-naphthoquinone (HNQ) acts as a highly efficient electron shuttle mediator and bioelectrocatalyst. Its unique quinone / hydroquinone reversible redox structure can build an "electron highway" between the electrode and microbial cells, significantly reducing the reaction energy barrier and accelerating the electron transfer rate. This rapid mass transfer not only directly catalyzes key electrochemical reactions such as denitrification and reduces the accumulation of intermediate products such as nitrite, but also optimizes the redox microenvironment, specifically enriches and regulates the activity of functional microbial communities such as denitrifying polyphosphate-accumulating bacteria. Thus, while reducing energy consumption, it enhances the metabolic efficiency of microorganisms, achieving a simultaneous and significant improvement in the system's nitrogen and phosphorus removal efficiency and stability.

[0055] ② Precisely regulate electronic distribution to enhance system performance.

[0056] The core advantage of adding electron mediators and starting the electrochemical device only in the anoxic section is that it utilizes electron mediators and micro-electric fields to construct a highly efficient "electron accelerator" in the anoxic section, rapidly achieving nitrite accumulation and efficient utilization of internal carbon sources. At the same time, by leveraging the "electron relay" and "microbial domestication" effects, this advantage is extended to the subsequent Anammox system, significantly improving the overall denitrification efficiency and system stability without increasing the power consumption of additional sections.

[0057] ③ Establish an energy recovery system to continuously and stably maintain current transmission.

[0058] This system employs a unique energy recovery mechanism, enabling continuous and stable current transfer between microorganisms within the EPD-Anammox system even when external power is cut off. Through extracellular electron transfer mediated by electron mesons, the EPD system efficiently converts the chemical energy released from the degradation of carbon sources by microorganisms into electrical energy, achieving a perfect coupling of endogenous respiration-based electricity generation and simultaneous nitrogen and phosphorus removal. This innovation not only breaks through the dependence of traditional processes on continuous energy supply but also demonstrates significant potential for energy conservation and emission reduction. Although the absolute power output needs improvement, its revolutionary significance for high-energy-consuming wastewater treatment modes is profound, providing a new technological path to achieving the vision of "energy self-sufficiency" for wastewater treatment plants.

[0059] ④ Innovate the "electron-medium-mediated Zn anode-graphite cathode" mechanism to achieve dual regulation of chemical phosphorus removal and biological metabolism.

[0060] Zn is released in situ from the Zn anode during electrolysis. 2＋ This mechanism not only achieves efficient phosphorus removal through chemical precipitation but also exhibits a significant synergistic effect with electron mediators. It selectively screens and enriches functional bacterial communities of DGAOs and DPAOs, such as Candidatus_Competibacter and Thaurea, enhancing internal carbon source conversion and extracellular electron transport processes, thus achieving deep coupling between phosphorus removal and denitrification metabolism.

[0061] As a cathode material, graphite, with its excellent electrical conductivity and chemical stability, can effectively accept electrons from the anode and transfer them to electron acceptors on the surface (such as H₂). ＋ NO3 - (etc.). Furthermore, graphite's large specific surface area and abundant active sites provide an ideal site for microbial attachment and electrocatalytic reactions. Crucially, the graphite cathode can efficiently regenerate and transfer electron mediators, synergizing with them. This is essential for enhancing extracellular electron transport in the EPD and Anammox systems, thus significantly accelerating nitrogen conversion rates. Under the reducing microenvironment and micro-electric field formed on the cathode surface, not only is the growth and metabolic activity of heterotrophic denitrifying bacteria such as *Denitratisoma* and *Rubrivivax* promoted, but suitable survival conditions are also provided for anaerobic ammonia-oxidizing bacteria, thereby significantly upregulating the expression of core functional genes such as *hzsA* and *hdh*.

[0062] ⑤ Significantly shortens the reaction cycle and greatly improves operational efficiency.

[0063] This technology breaks through the reaction time bottleneck of traditional processes. The reaction time of the anoxic stage in the EPD system is shortened from the traditional 60 minutes to 30-40 minutes; the reaction cycle of the Anammox system is significantly reduced from 12 hours to 8 hours, which significantly improves the system's processing efficiency and volumetric load.

[0064] ⑥ Construct a multi-pathway synergistic nitrogen removal system to enhance the system's resilience to shocks.

[0065] In the EPD segment, nitrite accumulation is promoted by upregulating key denitrification genes (napA, napB, narG, etc.); in the Anammox segment, residual Zn... 2＋ The electron mediator continued to function, significantly upregulating the core genes (hzs, hdh) of anaerobic ammonia oxidation and enriching Candidatus_Brocadia and heterotrophic denitrifying bacteria. This multi-pathway synergistic mechanism of "Anammox-heterotrophic denitrification" significantly improved nitrogen removal performance and the system's ability to resist water quality fluctuations.

[0066] ⑦ Significantly improves system processing efficiency, achieving simultaneous deep removal of carbon, nitrogen, and phosphorus.

[0067] After the system stabilized, it demonstrated excellent pollutant removal performance, with a COD removal rate of up to 78.12%, a total nitrogen removal rate of up to 88.66%, and a total phosphorus removal rate of 40.02%, achieving efficient and synergistic removal of carbon, nitrogen, and phosphorus pollutants in wastewater.

[0068] It should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any modifications or alterations made by those skilled in the art without departing from the scope of the present invention to create equivalent embodiments based on the disclosed technical content shall fall within the protection scope of the present invention.

Claims

1. A method for electrochemical wastewater treatment based on an EPD-Anammox system mediated by electronic messons, characterized in that, An electrochemical wastewater treatment device based on the EPD-Anammox system mediated by electronic mediators was used, followed by the following steps: 1) EPD reaction stage: The organic-rich influent I from the first water storage tank (2) is pumped into the EPD reactor (1) through the first influent pump (2-1), and the stirrer (1-1) is turned on at the same time for anaerobic stirring for 1.5-2 hours; then the organic-rich influent I from the second water storage tank (3) is pumped into the EPD reactor (1). - -N and PO4 3- -P's influent Ⅱ is pumped into EPD reactor (1) through the second influent pump (3-1). At the same time, the solution containing electron mediators in the storage tank (6) is added to EPD reactor (1) through the first sewage pump (6-1), and the electrochemical device (5) is turned on to react for 5-10 minutes. After 35-50 minutes of anoxic stirring, the stirrer (1-1) is stopped, and sedimentation is allowed for 30-40 minutes. After sedimentation, the aeration pump (4) is turned on to aerate for 30-40 minutes. After the aeration pump (4) is turned off, the mixture is allowed to stand for 1-2 hours. The EPD effluent is temporarily stored in the third storage tank (8) through the drain valve (6-2). 2) Anammox reaction stage: The EPD effluent from the third water tank (8) and the sewage from the fourth water tank (9) are fed into the Anammox reactor (7) through the second sewage pump (8-1) and the third sewage pump (9-1), respectively, while the circulation pump (7-1) is turned on to carry out the reaction.

2. The electrochemical wastewater treatment method based on the EPD-Anammox system mediated by electronic messons according to claim 1, characterized in that, In step 1), influent I uses sodium acetate as the carbon source, with a COD of 313±15 mg / L, an influent time of 20 min, and an influent volume of 4.5 L; influent II uses sodium nitrate and dipotassium hydrogen phosphate as the nitrogen and phosphorus sources, respectively, and NO3-... - -N concentration was 70±5 mg / L, PO4 3- -P concentration is 10±5mg / L, influent time is 5min, influent volume is 0.5-1.0L; effluent ratio is 50-60%.

3. The electrochemical wastewater treatment method based on the EPD-Anammox system mediated by electronic messons according to claim 1, characterized in that, In step 1), the electrochemical device (5) consists of an EPD electrode device (1-2) and an Anammox electrode device (7-2). In the EPD system, the EPD electrode device (1-2) consists of 3 zinc anodes and 3 graphite cathodes arranged in a staggered manner on the inner wall of the EPD reactor and connected to a DC power supply through wires. When the influent II enters, the EPD electrode device (1-2) is turned on simultaneously with a current density of 1.5-2.5 mA / cm² and an energizing time of 5-10 min. In the Anammox system, the Anammox electrode device (7-2) consists of 1 zinc anode and 1 graphite cathode arranged on the inner wall of the Anammox reactor and connected to a DC power supply through wires. The Anammox electrode device (7-2) is turned on simultaneously with the EPD influent II entering with a current density of 1.5-2.5 mA / cm² and an energizing time of 5-10 min.

4. The electrochemical wastewater treatment method based on the EPD-Anammox system mediated by electronic messons according to claim 1, characterized in that, In step 2), ammonium chloride (NH4) is added to the influent of the Anammox reactor. ＋ -N source, NH4 ＋ -N is 35-40 mg / L, and the EPD effluent contains NO2. - -N source, NO2 - -N is 45.5-52 mg / L, and any deficiency should be supplemented manually. The water retention time should be controlled at 8-10 hours, and the circulation pump should circulate at 200-300%.

5. The electrochemical wastewater treatment method based on the EPD-Anammox system mediated by electronic messons according to claim 1, characterized in that, In step 1), the solution containing the electron meson is 2-hydroxy-1,4-naphthoquinone, with a dosage concentration of 1.5-2.0 mg / L, and is added to the anoxic section of the EPD system. The addition frequency is once every 3 days, and it is added synchronously with the influent II. The residual electron meson 2-hydroxy-1,4-naphthoquinone and its intermediate are added to the Anammox reactor along with the EPD effluent.

6. The electrochemical wastewater treatment method based on the EPD-Anammox system mediated by electronic messons according to claim 1, characterized in that, The EPD-Anammox system electrochemical wastewater treatment device based on electronic mediators includes an EPD reactor, a water storage tank, an aeration pump (4), an electrochemical device, and an Anammox reactor. The first water storage tank (2) is connected to the EPD reactor (1) via a first inlet pump (2-1), and the second water storage tank (3) is connected to the EPD reactor (1) via a second inlet pump (3-1). The aeration pump (4) is connected to the bottom of the EPD reactor (1) for aeration and oxygen supply. The electrochemical device (5) is connected to the EPD reactor via a pipeline. The reactor (1) is connected to the Anammox reactor (7). The EPD reactor (1) is equipped with a stirrer (1-1) and an EPD electrode device (1-2). The storage tank (6) is connected to the EPD reactor (1) via the first sewage pump (6-1). The third water storage tank (8) is connected to the EPD reactor (1). The third water storage tank (8) and the fourth water storage tank (9) are connected to the Anammox reactor (7) via the second sewage pump (8-1) and the third sewage pump (9-1), respectively.

7. The electrochemical wastewater treatment method based on the EPD-Anammox system mediated by electronic messons according to claim 6, characterized in that, The Anammox reactor (7) is equipped with a circulation pump (7-1), a gas production circulation pipe (10), and an Anammox electrode device (7-2). The circulation pump (7-1) and the gas production circulation pipe (10) are both connected to the bottom outlet of the Anammox reactor (7). The Anammox reactor (7) is arranged from bottom to top as a granular sludge zone (7-2-5), a mixing zone (7-2-6), and a sludge-water separation zone (7-2-7). The Anammox electrode device (7-2) is located in the mixing zone (7-2-6).

8. The electrochemical wastewater treatment method based on the EPD-Anammox system mediated by electronic messons according to claim 6, characterized in that, A drain valve (6-2) is installed on the pipeline connecting the third water tank (8) and the EPD reactor 1. The EPD electrode device (1-2) is located above the drain valve. The EPD electrode device (1-2) is composed of three first Zn anodes (1-2-1) and three first graphite cathodes (1-2-2) fixed on the first conductor (1-2-4) by the first binding rib (1-2-3). The Zn anode size is φ8×100mm and the graphite cathode size is φ8×100mm.

9. The electrochemical wastewater treatment method based on the EPD-Anammox system mediated by electronic messons according to claim 6, characterized in that, The Anammox electrode device (7-2) consists of a second Zn anode (7-2-1) and a second graphite cathode (7-2-2) fixed to a second conductor (7-2-4) by a second binding rib (7-2-3). The Zn anode has a size of φ8×100mm and the graphite cathode has a size of φ8×100mm.

10. The electrochemical wastewater treatment method based on the EPD-Anammox system mediated by electronic messons according to claim 6, characterized in that, The first inlet pump (2-1) and the second inlet pump (3-1) are PVDF magnetic circulation pumps; the first sewage pump (6-1), the second sewage pump (8-1), and the third sewage pump (9-1) are WQ / QW type submersible sewage pumps.

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