Electrode dependent anaerobic ammonia oxidation process

Abstract

The invention discloses an electrode dependent anaerobic ammonium oxidation process, which belongs to the technical field of water pollution and comprises the following steps: enriching floating anaerobic ammonium oxidation bacteria, preparing a three-electrode system, preparing a culture medium, switching and domesticating electron acceptors and collecting gas generated by reaction. The method gets rid of dependence on nitrite, effectively simplifies the influent water quality requirement and the process regulation and control flow, transmits electrons through external voltage to replace nitrite as a unique electron acceptor, can realize efficient anaerobic oxidation of ammonia nitrogen without additional addition of nitrite and nitrate, reduces the process complexity and the operation cost, and is suitable for large-scale industrial production. And the adaptation range of inlet water quality is widened.

Description

Technical Field

[0001] This invention relates to the field of water pollution technology, specifically to an electrode-dependent anaerobic ammonia oxidation process. Background Technology

[0002] With the acceleration of industrial development and urbanization, the discharge of various types of wastewater with high ammonia nitrogen and low organic carbon and low nitrogen ratio, such as landfill leachate and aquaculture wastewater, has been increasing year by year. The efficient denitrification treatment of such wastewater has become a key requirement in the field of environmental protection. Anaerobic ammonia oxidation technology has received widespread attention in the treatment of ammonia nitrogen wastewater due to its advantages such as low energy consumption and no need for large-scale aeration.

[0003] However, traditional anaerobic ammonia oxidation processes rely on nitrite as an electron acceptor, requiring the addition of nitrite to the reaction system or the generation of nitrite through a pre-nitrification unit. This not only increases the difficulty of process control and operating costs, but also makes the process susceptible to shocks caused by fluctuations in nitrite concentration, leading to a decrease in treatment efficiency. Furthermore, it has poor adaptability to influent water quality and is difficult to treat ammonia nitrogen wastewater with extremely low or no nitrite content.

[0004] Traditional processes are prone to the accumulation of nitrate byproducts during the reaction, making it difficult to meet the total nitrogen standards in the effluent. This necessitates the addition of an extra nitrate removal unit, further increasing equipment investment and subsequent treatment costs.

[0005] Traditional processes contain nitric oxide intermediates in their reaction pathways. These intermediates are easily converted into potent greenhouse gases such as nitrous oxide, posing significant ecological and environmental risks and contradicting the current demand for green and low-carbon development.

[0006] Based on this, the present invention designs an electrode-dependent anaerobic ammonia oxidation process to solve the above problems. Summary of the Invention

[0007] To address the aforementioned shortcomings of existing technologies, this invention provides an electrode-dependent anaerobic ammonia oxidation process, comprising the following steps: S1: Inoculate the initial biomass into the membrane bioreactor and continuously add an inorganic culture medium containing ammonia nitrogen into the membrane bioreactor; S2: Select a single-chamber or double-chamber microbial electrolysis cell and configure a three-electrode system: the working anode electrode is selected from graphite rod, carbon felt or carbon cloth, the cathode electrode is selected from platinum mesh or graphite rod, and the reference electrode is selected from Ag / AgCl electrode. S3: Take the inorganic culture medium from S1, dissolve it, boil it, and pass a mixture of N2 and CO2 gas to remove dissolved oxygen. Cool it, add KHCO3 to dissolve it, and adjust the pH of the culture medium to 7.0-7.5 to obtain the inorganic culture medium. S4: Inject the sterile culture medium from S3 into the sealed electrolytic cell, set the working electrode potential to 0.6V, and continuously monitor until no obvious current is generated and NH4+ is released. + Concentration change rate ≤ 5%; S5: Inoculate the anaerobic ammonia-oxidizing bacteria enriched in S1 into the electrolytic cell that has passed the verification in S4, adjust the bacterial inoculation concentration, and add NH4+ to the electrolytic cell. + The inorganic culture medium was maintained at the same temperature and stirring conditions as in S1, and monitoring was continued until NH4 was reached. + Removal rate ≥90% and biofilm thickness ≥10μm; S6: Initiate electron acceptor switching acclimatization to gradually reduce NO2 in the influent. - Concentration, until the concentration reaches 0; S7: Continuously introduce NO2-free gas into the electrolytic cell. - NH4+ containing nitrates and exogenous organic carbon + Water intake, maintaining a working electrode potential of 0.6V, operating temperature of 20-36℃, and pH of 7.0-7.5; S8: Collect the gas produced by the reaction through a gas bag.

[0008] Furthermore, in S1, the dry weight concentration of the biomass is 10-50 g / L, the proportion of anaerobic ammonia oxidizing bacteria is ≥60%, the proportion of attached heterotrophic bacteria is ≤10%, and the proportion of inorganic particles is 30-40%.

[0009] Furthermore, the operating conditions of the membrane bioreactor are pH 7.5-8.0, culture temperature 20-36℃, and stirring speed 100-200 r / min.

[0010] Furthermore, the inorganic culture medium contains CaCl2 100-120 mg / L, MgSO4 300-400 mg / L, KH2PO4 30-50 mg / L, KHCO3 400-600 mg / L and trace element solution; The trace element solution contains 100-200 μM FeSO4·7H2O, 10-30 μM MnCl2·4H2O, 5-15 μM ZnSO4·7H2O, 1-5 μM CuSO4·5H2O, 1-5 μM CoCl2·6H2O, and 1-5 μM Na2MoO4·2H2O.

[0011] Furthermore, in S2, the working volume of a single chamber is 300-500 mL, and the working volume of each chamber in a dual-chamber configuration is 200-300 mL.

[0012] Furthermore, in S2, the acid washing and water washing steps for the working electrode and the counter electrode are as follows: first, soak in 1-5 mol / L hydrochloric acid solution for 12-24 hours, stirring once every 4-6 hours during the soaking period at a stirring rate of 50-100 r / min; then rinse with deionized water until the pH of the rinsing solution is 6.5-7.5; and then purge with nitrogen gas for 30-60 minutes.

[0013] Furthermore, in S5, the bacterial inoculum concentration was adjusted to 0.1-0.9 mg-protein / mL. -1 (mg protein / mL).

[0014] Furthermore, S6 specifically involves: initiating electron acceptor switching acclimatization, reducing NO2 in the influent each time. - Maintain NH4 concentration at 20%-30%. + With the concentration kept constant, each concentration gradient was run for 3-7 days, during which NH4 was monitored every 12 hours. + Removal rate, NO2 - The residual amount and current changes were recorded every 60 seconds using a potentiostat, repeating the above steps for NO2. - Concentration reduction operation until NO2 in the influent... - The concentration dropped below the detection limit, and was observed to be related to NH4 within three consecutive monitoring periods. + Consumption is positively correlated with the generation of stable current.

[0015] Compared with the prior art, the beneficial effects of this invention are as follows: 1. This invention does not rely on nitrite as the sole electron acceptor, effectively simplifying the influent water quality requirements and process control procedures. By transferring electrons through an external voltage instead of nitrite as the sole electron acceptor, it avoids the impact of insufficient nitrite nitrogen content in the influent on the efficient anaerobic oxidation of ammonia nitrogen, reduces process complexity and operating costs, and broadens the range of influent water quality adaptability.

[0016] 2. This invention produces no nitrate byproducts during the reaction process, directly yielding high-quality effluent with low nitrate and low total nitrogen, significantly improving effluent quality. It eliminates the need for additional nitrate removal steps, reducing equipment investment in subsequent treatment stages such as denitrification units, avoiding related reagent consumption and maintenance labor costs, and lowering the overall cost of subsequent treatment stages. This invention can meet higher water quality discharge requirements at the local or industry level.

[0017] 3. The reaction pathway of this invention does not involve nitric oxide intermediates, thus avoiding the formation of the greenhouse gas nitrous oxide, exhibiting excellent environmental friendliness and meeting the needs of green and low-carbon development.

[0018] 4. The process of this invention does not rely on external organic carbon and uses only ammonia nitrogen as the sole electron donor. It can be precisely adapted to the treatment scenarios of low carbon-to-nitrogen ratio wastewater with high ammonia nitrogen and low organic carbon, such as landfill leachate and aquaculture wastewater, thus broadening the applicability of anaerobic ammonia oxidation process.

[0019] 5. The electrons released during the oxidation of ammonia nitrogen by anaerobic ammonia-oxidizing bacteria in this invention can be efficiently captured by electrodes, realizing the directional transfer and collection of electrons, achieving synergy between wastewater treatment and energy recovery, and improving resource utilization efficiency and process economic value. Attached Figure Description

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

[0021] Figure 1 A comparison of the relative abundance of microbial communities between the conventional anaerobic ammonium oxidation group and the electrode-dependent anaerobic ammonium oxidation group; Figure 2 This invention is based on the absence of exogenous NO2. - Performance graph under -N conditions; Figure 3 This is a performance diagram of the invention in open-circuit voltage mode; Figure 4 To achieve the present invention, NO2 is added again to the influent. - Performance graph under -N; Figure 5 This is a diagram showing the operational performance of the present invention after autoclaving; Figure 6 This is a schematic diagram of the single-chamber microbial electrolysis cell structure of the present invention; Figure 7 This is a schematic diagram of the dual-chamber microbial electrolysis cell structure of the present invention. Detailed Implementation

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

[0023] Example 1: This example provides an electrode-dependent anaerobic ammonium oxidation process, including the following steps: S1: Initial inoculum biomass is obtained from an anaerobic ammonia oxidation upflow column reactor. The dry weight concentration of the biomass is 10 g / L, with anaerobic ammonia oxidizing bacteria accounting for ≥60%, attached heterotrophic bacteria accounting for ≤10%, and inorganic particles accounting for 30%. The composition of the anaerobic ammonia oxidizing bacteria is as follows: Figure 1 As shown, the inoculated biomass was fed into a membrane bioreactor to enrich planktonic anaerobic ammonia-oxidizing bacteria. The operating conditions of the membrane bioreactor were: pH 7.5, culture temperature 20℃ (marine species), stirring speed 100 r / min, and continuous introduction of a N2-CO2 mixture (N2 to CO2 volume ratio 2:8) at a flow rate of 10 mL / min to maintain the anaerobic environment. The hydraulic retention time was 24 h, and NH4+ containing 2.5 mM ammonia nitrogen was continuously added. + Inorganic culture medium; The inorganic culture medium contains 100 mg / L CaCl2, 300 mg / L MgSO4, 30 mg / L KH2PO4, 400 mg / L KHCO3, and trace element solution; The trace element solution contains 100 μM FeSO4·7H2O, 10 μM M MnCl2·4H2O, 5 μM ZnSO4·7H2O, 1 μM CuSO4·5H2O, 1 μM CoCl2·6H2O, and 1 μM Na2MoO4·2H2O. S2: A dual-chamber microbial electrolysis cell (each chamber has a working volume of 200 mL) is selected, and a three-electrode system is configured: the anode working electrode is selected from a graphite rod (8 cm in length and 0.5 cm in diameter), the cathode counter electrode is selected from a graphite rod (8 cm in length and 0.5 cm in diameter), and the reference electrode is an Ag / AgCl electrode. The working electrode and the counter electrode are pretreated by first soaking them in 1 mol / L hydrochloric acid solution for 12 h, stirring once every 4 h during the soaking period at a stirring rate of 50 r / min, then rinsing with deionized water until the pH of the rinsing solution is 6.5, and then purging with nitrogen for 30 min to remove residual moisture and oxygen. The reference electrode was soaked in 3M NaCl solution for 12 hours and rinsed three times with sterile water. The electrolytic cell and all electrodes were sealed with butyl rubber plugs and epoxy resin to ensure no leakage and to guarantee the stability of the subsequent anaerobic environment. S3: Take the inorganic culture medium from S1, dissolve it, boil the inorganic culture medium and pass in a mixture of 80% N2 and 20% CO2 for 20 minutes to remove dissolved oxygen. Transfer the deoxygenated culture medium to an anaerobic chamber and cool it to room temperature. Weigh it in the anaerobic chamber at a rate of 500 mg per liter of culture medium and add KHCO3 to dissolve it. Adjust the pH of the culture medium to 7.0 to obtain the inorganic culture medium. S4: Inject the sterile culture medium from S3 into the sealed electrolytic cell. Set the working electrode potential to 0.6V (vs. standard hydrogen electrode SHE) using a potentiostat and monitor continuously for 24 hours, taking samples every 12 hours. Detect NH4+ using Nessler's reagent spectrophotometry. + The concentration was verified to be acceptable only if no significant current was generated during the monitoring period (current density ≤ 0.01 mA / m³). 2 And NH4 + The concentration change rate is ≤5%, and after excluding interference from non-biological reactions and verifying that it is qualified, inoculation can proceed. S5: Inoculate the anaerobic ammonia-oxidizing bacteria enriched in S1 into the electrolytic cell that has passed the verification in S4, adjust the bacterial inoculum concentration to 0.1 mg protein / mL, and add 2.5 mM NH4+ to the electrolytic cell. + An inorganic culture medium was used to maintain the temperature and stirring conditions in S1, allowing the bacterial community to metabolize via conventional anaerobic ammonia oxidation. NH4 samples were taken every 24 hours during operation. + The concentration of NH4 was determined by Nessler's reagent spectrophotometry. + The standard for NH4 concentration and removal rate is achieved within three consecutive monitoring cycles (24 hours each). + Removal rate ≥90%; S6: Initiate electron acceptor switching acclimatization, reducing NO2 in the influent each time. - 20% concentration, maintaining NH4 + With the concentration kept constant, each concentration gradient was run for 3 days, during which NH4 was monitored every 12 hours. + Removal rate, NO2 - The residual amount and current changes were recorded every 60 seconds using a potentiostat, repeating the above steps for NO2. - Concentration reduction operation until NO2 in the influent... - The concentration dropped below the detection limit (<5 μM), and was observed to be related to NH4+ within three consecutive monitoring cycles (24 h each). + The generation of a stable current with a positive correlation to the consumption (current density fluctuation ≤10%) indicates that the microbial community has been successfully domesticated and can use the electrode as the sole electron acceptor through extracellular electron transfer. S7: Continuously introduce NO2-free gas into the electrolytic cell. - NH4+ containing nitrates and exogenous organic carbon + Inlet water, the NH4 in the inlet water + The concentration was 2.5 mM, the hydraulic retention time was maintained at 24 h, the stirring speed was 100 r / min, the working electrode potential was maintained at 0.6 V by a potentiostat, the operating temperature was 20 ℃, and the pH was maintained at 7.0. S8: Collect the gas (nitrogen) produced by the reaction through a gas bag. Analyze the gas composition every 24 hours using an SRI 8610C gas chromatograph. Clean the excess biofilm on the electrode surface every 15 days using a sterile scraper. The biofilm thickness should be 20-50 μm to avoid limiting mass transfer.

[0024] Example 2: This example provides an electrode-dependent anaerobic ammonia oxidation process, including the following steps: S1: Initial inoculum biomass was obtained from an anaerobic ammonia oxidation upflow column reactor. The dry weight concentration of the biomass was 50 g / L, with anaerobic ammonia oxidizing bacteria accounting for ≥60%, attached heterotrophic bacteria accounting for ≤10%, and inorganic particles accounting for 40%. The inoculum biomass was then introduced into a membrane bioreactor to enrich planktonic anaerobic ammonia oxidizing bacteria. The operating conditions of the membrane bioreactor were: pH 8.0, culture temperature 36℃, stirring speed 200 r / min, and continuous introduction of N2-CO2 mixed gas (N2 to CO2 volume ratio 2:8) at a flow rate of 10 mL / min to maintain the anaerobic environment. The hydraulic retention time was 24 h, and 10 mM ammonia nitrogen (NH4) was continuously added. + Inorganic culture medium containing 12 mM nitrite and 12 mM nitrite; The inorganic culture medium contains CaCl2 120 mg / L, MgSO4 400 mg / L, KH2PO4 50 mg / L, KHCO3 600 mg / L and trace element solution; The trace element solution contains 200 μM FeSO4·7H2O, 30 μM M MnCl2·4H2O, 15 μM ZnSO4·7H2O, 5 μM CuSO4·5H2O, 5 μM CoCl2·6H2O, and 5 μM Na2MoO4·2H2O. S2: A single-chamber microbial electrolysis cell (with a single chamber working volume of 500 mL) is selected, and a three-electrode system is configured: the anode working electrode is selected from carbon cloth (surface area of ​​20 cm²). 2 The cathode electrode is selected from a platinum mesh (10 cm² in area). 2 The reference electrode is an Ag / AgCl electrode. The working electrode and the counter electrode were pretreated by first soaking them in 5 mol / L hydrochloric acid solution for 24 hours, stirring once every 6 hours during the soaking period at a stirring rate of 100 r / min, then rinsing them with deionized water until the pH of the rinsing solution was 7.5, and then purging them with nitrogen for 60 minutes to remove residual moisture and oxygen. The reference electrode was soaked in 3M NaCl solution for 24 hours and rinsed 5 times with sterile water. The electrolytic cell and all electrodes were sealed with butyl rubber plugs and epoxy resin to ensure no leakage and to guarantee the stability of the subsequent anaerobic environment. S3: Take the inorganic culture medium from S1, add 2mM 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid (HEPES) buffer (pH 7.8), dissolve, boil the inorganic culture medium and purge with a mixture of 80% N2 and 20% CO2 for 30 min to remove dissolved oxygen, transfer the deoxygenated culture medium to an anaerobic chamber and cool to room temperature, weigh 500 mg of culture medium per liter in the anaerobic chamber and add KHCO3 to dissolve, adjust the pH of the culture medium to 7.5 to obtain the inorganic culture medium; S4: Inject the sterile culture medium from S3 into the sealed electrolytic cell. Set the working electrode potential to 0.6V (vs. standard hydrogen electrode SHE) using a potentiostat and monitor continuously for 48 hours, taking samples every 12 hours. Detect NH4+ using Nessler's reagent spectrophotometry. + The concentration was verified to be acceptable only if no significant current was generated during the monitoring period (current density ≤ 0.01 mA / m³). 2 And NH4 + The concentration change rate is ≤5%, and after excluding interference from non-biological reactions and verifying that it is qualified, inoculation can proceed. S5: Inoculate the anaerobic ammonia-oxidizing bacteria enriched in S1 into the electrolytic cell that has passed the verification in S4, adjust the bacterial inoculation concentration to 0.9 mg protein / mL, and add 10 mM NH4+ to the electrolytic cell. + and 12 mM NO2 - An inorganic culture medium was used to maintain the temperature and stirring conditions in S1, allowing the bacterial community to metabolize via conventional anaerobic ammonia oxidation. NH4 samples were taken every 24 hours during operation. + and NO2 - The concentration of NH4 was determined by Nessler's reagent spectrophotometry. + NO2 concentration and determination by naphthylethylenediamine method - The standard for NH4 concentration and removal rate is achieved within three consecutive monitoring cycles (24 hours each). + Removal rate ≥90% and NO2 - Removal rate ≥90%; S6: Initiate electron acceptor switching acclimatization, reducing NO2 in the influent each time. - 30% concentration, maintaining NH4 + With the concentration kept constant, each concentration gradient was run for 7 days, during which NH4 was monitored every 12 hours. + Removal rate, NO2 - The residual amount and current changes were recorded every 60 seconds using a potentiostat, repeating the above steps for NO2. - Concentration reduction operation until NO2 in the influent... - The concentration dropped below the detection limit (<5 μM), and was observed to be related to NH4+ within three consecutive monitoring cycles (24 h each). +The generation of a stable current with a positive correlation to the consumption (current density fluctuation ≤10%) indicates that the microbial community has been successfully domesticated and can use the electrode as the sole electron acceptor through extracellular electron transfer. S7: Continuously introduce NO2-free gas into the electrolytic cell. - NH4+ containing nitrates and exogenous organic carbon + Inlet water, the NH4 in the inlet water + The concentration was 10 mM, the hydraulic retention time was maintained at 24 h, the stirring speed was 150 r / min, the working electrode potential was maintained at 0.6 V by a potentiostat, the operating temperature was 36 ℃, and the pH was maintained at 7.5. S8: Collect the gas (nitrogen) produced by the reaction through a gas bag. Analyze the gas composition by SRI 8610C gas chromatography every 24 hours. Clean the excess biofilm on the electrode surface with a sterile scraper every 30 days. The biofilm thickness should be 20-50 μm to avoid mass transfer limitation.

[0025] Example 3 (Subsequent experiments will be based on the data from this example): This example provides an electrode-dependent anaerobic ammonia oxidation process, including the following steps: S1: Initial inoculum biomass was obtained from an anaerobic ammonia oxidation upflow column reactor. The biomass had a dry weight concentration of 20 g / L, with anaerobic ammonia oxidizing bacteria accounting for ≥60%, attached heterotrophic bacteria accounting for ≤10%, and inorganic particles accounting for 32%. The inoculum biomass was then introduced into a membrane bioreactor to enrich planktonic anaerobic ammonia oxidizing bacteria. The operating conditions of the membrane bioreactor were: pH 7.8, culture temperature 25℃, stirring speed 160 r / min, and continuous introduction of N2-CO2 mixed gas (N2 to CO2 volume ratio 2:8) at a flow rate of 10 mL / min to maintain the anaerobic environment. The hydraulic retention time was 24 h, and NH4+ containing 5 mM ammonia nitrogen (NH4+) was continuously added. + Inorganic culture medium; The inorganic culture medium contains CaCl2 105 mg / L, MgSO4 310 mg / L, KH2PO4 45 mg / L, KHCO3 520 mg / L and trace element solution; The trace element solution contains 130 μM FeSO4·7H2O, 17 μM M MnCl2·4H2O, 8 μM ZnSO4·7H2O, 2 μM CuSO4·5H2O, 3 μM CoCl2·6H2O, and 5 μM Na2MoO4·2H2O. S2: A dual-chamber microbial electrolysis cell (each chamber has a working volume of 200 mL) is selected, and a three-electrode system is configured: the anode working electrode is selected from carbon felt (surface area of ​​17 cm²). 2 The cathode electrode is selected from graphite rods (8cm in length and 0.5cm in diameter), and the reference electrode is an Ag / AgCl electrode. The working electrode and the counter electrode are pretreated by first soaking them in 4 mol / L hydrochloric acid solution for 24 h, stirring once every 6 h during the soaking period at a stirring rate of 60 r / min, then rinsing with deionized water until the pH of the rinsing solution is 7.2, and then purging with nitrogen for 50 min to remove residual moisture and oxygen. The reference electrode was soaked in 3M NaCl solution for 24 hours and rinsed 4 times with sterile water. The electrolytic cell and all electrodes were sealed with butyl rubber plugs and epoxy resin to ensure no leakage and to guarantee the stability of the subsequent anaerobic environment. S3: Take the inorganic culture medium from S1, add 2mM 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid (HEPES) buffer (pH 7.8), dissolve, boil the inorganic culture medium and purge with a mixture of 80% N2 and 20% CO2 for 20 min to remove dissolved oxygen, transfer the deoxygenated culture medium to an anaerobic chamber and cool to room temperature (maintain a 95% Ar-5% CO2 atmosphere and a temperature of 22℃ in the anaerobic chamber), weigh out 500mg of culture medium per liter in the anaerobic chamber and add KHCO3 to dissolve, adjust the pH of the culture medium to 7.2 to obtain the inorganic culture medium; S4: Inject the sterile culture medium from S3 into the sealed electrolytic cell. Set the working electrode potential to 0.6V (vs. standard hydrogen electrode SHE) using a potentiostat and monitor continuously for 24 hours, taking samples every 12 hours. Detect NH4+ using Nessler's reagent spectrophotometry. + The concentration was verified to be acceptable only if no significant current was generated during the monitoring period (current density ≤ 0.01 mA / m³). 2 And NH4 + The concentration change rate is ≤5%, and after excluding interference from non-biological reactions and verifying that it is qualified, inoculation can proceed. S5: Inoculate the anaerobic ammonia-oxidizing bacteria enriched in S1 into the electrolytic cell that has passed the verification in S4, adjust the bacterial inoculation concentration to 0.8 mg protein / mL, and add 5 mM NH4+ to the electrolytic cell. + An inorganic culture medium was used to maintain the temperature and stirring conditions in S1, allowing the bacterial community to metabolize via conventional anaerobic ammonia oxidation. NH4 samples were taken every 24 hours during operation. + The concentration of NH4 was determined by Nessler's reagent spectrophotometry. + The standard for NH4 concentration and removal rate is achieved within three consecutive monitoring cycles (24 hours each). + Removal rate ≥90%; S6: Initiate electron acceptor switching acclimatization, reducing NO2 in the influent each time. - 20% concentration, maintaining NH4 + With the concentration kept constant, each concentration gradient was run for 4 days, during which NH4 was monitored every 12 hours. + Removal rate, NO2- The residual amount and current changes were recorded every 60 seconds using a potentiostat, repeating the above steps for NO2. - Concentration reduction operation until NO2 in the influent... - The concentration dropped below the detection limit (<5 μM), and was observed to be related to NH4+ within three consecutive monitoring cycles (24 h each). + The generation of a stable current with a positive correlation to the consumption (current density fluctuation ≤10%) indicates that the microbial community has been successfully domesticated and can use the electrode as the sole electron acceptor through extracellular electron transfer. S7: Continuously introduce NO2-free gas into the electrolytic cell. - NH4+ containing nitrates and exogenous organic carbon + Inlet water, the NH4 in the inlet water + The concentration was 5 mM, the hydraulic retention time was maintained at 24 h, the stirring speed was 120 r / min, the working electrode potential was maintained at 0.5 V by a potentiostat, the operating temperature was 25 ℃ (marine species), and the pH was maintained at 7.4. S8: Collect the gas (nitrogen) produced by the reaction through a gas bag. Analyze the gas composition every 24 hours using an SRI 8610C gas chromatograph. Clean the excess biofilm on the electrode surface every 20 days using a sterile scraper. The biofilm thickness should be 20-50 μm to avoid limiting mass transfer.

[0026] Explanatory Example: This explanatory example will explain the principles of the traditional anaerobic ammonium oxidation process and the anaerobic ammonium oxidation process of the present invention; Traditional anaerobic ammonium oxidation process: In traditional anaerobic ammonia oxidation processes, ammonia nitrogen (NH4) + The oxidation of nitrite (NO2) depends on nitrite (NO2). - As an electron acceptor, the reaction takes place in an anaerobic ammonia oxidase, producing nitric oxide (NO) and hydrazine (N2H4) as intermediates, ultimately generating nitrogen gas (N2). The overall reaction is as follows: Step 1: Nitrite is reduced to nitric oxide; NO2 - Under the action of copper-containing nitrite reductase, it accepts one electron and is reduced to NO: The electrons needed in step one come from step four; Step 2: Nitric oxide condenses with ammonia to form hydrazine; NO and NH3, under the catalysis of the hydrazine synthase complex, consume 3 electrons and condense into a high-energy intermediate, namely hydrazine: The electrons required in step two are provided by a dedicated electron transfer module (ETM) that obtains electrons from the quinone pool; Step 3: Hydrazine oxidation produces nitrogen gas; Hydrazine is oxidized by hydrazine dehydrogenase to produce the final product N2, releasing four high-energy electrons: Step 4: Electron Cycle and Energy Capture; Of the four electrons released in step four, three are refluxed back to step two via the quinone pool and ETM for the synthesis of N2H4, while the remaining one is used to drive the NO2 synthesis in step one. - Reduction, this electron cycle process accompanied by the transmembrane transport of protons, establishes the proton motive force, which ultimately drives ATP synthase to generate ATP.

[0027] The anaerobic ammonia oxidation process of this invention: Step 1: Ammonia is directly oxidized to hydroxylamine (key difference); NH4 + The activation of hydroxylamine no longer depends on condensation with NO, but is directly oxidized to hydroxylamine by a special hydroxylamine oxidoreductase. This step obtains an oxygen atom from a water molecule and releases two electrons into the extracellular space. Isotope labeling experiments (using D2O) confirmed that water is the source of oxygen atoms; Step 2: Hydroxylamine condenses with ammonia to form hydrazine; The generated NH2OH molecule directly condenses with another NH3 molecule under the action of hydrazine synthase to form N2H4. This step does not consume electrons. Step 3: Hydrazine oxidation produces nitrogen gas (electron source); This step is the same as the traditional pathway, catalyzed by highly expressed hydrazone dehydrogenase, producing N2 and releasing 4 electrons: Step 4: Extracellular electron transport (core innovation); The six electrons generated in steps one and three no longer circulate internally, but are transferred to the extracellular space via a newly activated extracellular electron transport chain. This pathway is similar to that of electrically active bacteria such as Geobacter and Shewanella. Electrons are injected into the quinone pool of the cell membrane via NADH dehydrogenase or formate dehydrogenase. The electrons in the quinone pool are oxidized by a tetraheme C cytochrome; Electrons pass through the periplasmic space and are transported by the periplasmic monoheme C-type cytochrome shuttle. Ultimately, electrons are directly transferred to extracellular receptors such as electrodes or graphene via the outer membrane porin-cytochrome complex and polyheme C cytochrome.

[0028] In summary, the difference between this invention and traditional processes lies in the fact that the traditional approach... It relies on enzyme systems such as Nir, HZS, and ETM. ETM provides electrons for the reduction of NO to NH2OH. This invention pertains to electrode-dependent anaerobic ammonium oxidation processes. NH2OH is directly produced from NH4 + Oxidation-generated, independent of NO, downregulates ETM and Nir systems, and instead activates extracellular electron transport pathways such as Geobacter and Shewanella, including cytochrome c, formate dehydrogenase, and outer membrane porin-cytochrome complex.

[0029] in, Figure 1 The table below shows a comparison of the relative abundance of microbial communities between the conventional anaerobic ammonium oxidation group and the electrode-dependent ammonium oxidation group. Specific changes are illustrated in the table below: Fungi CA Group % AA group% Trend of change Main functions g_Candidatus_Brocadia 64.02 37.99 Significant decline Candida / Brocardia, classic anaerobic ammonia-oxidizing bacteria. The loss of their absolute dominance demonstrates their high dependence on nitrite and inadequacy to anodic environments. g_Candidatus_Jettenia 1.02 4.89 Significant increase *Jetene* spp. are electroactive anaerobic ammonia-oxidizing bacteria. Their abundance increased nearly fivefold, making them key core bacteria for achieving anodic anaerobic ammonia oxidation, capable of utilizing the electrode as an electron acceptor. g_unclassified_Candidatus_Brocadiaceae 2.89 1.87 decline Unclassified members of the family Candidatus Brocadiaceae, trending in line with Candidatus Brocadia. g_Candidatus_Kentron 0.66 1.20 rise Belongs to the class Gamma-Proteobacteria g_Nitrosomonas 0.35 0.74 rise Nitrosomonas, ammonia-oxidizing bacteria (AOB). Extremely low abundance indicates that the anodic ammonia oxidation process is not dominated by nitrifying bacteria. Their presence may provide trace amounts of nitrite. g_Nitrospira 0.48 1.57 rise Nitrifying spirochetes (involved in nitrite oxidation) have low abundance and limited function. g_lgnavibacterium 1.29 1.38 Basically stable *Lazybacterium* is a genus of electroactive bacteria that supports anaerobic ammonia-oxidizing metabolism through interspecies electron transfer. g_Klebsiella 0.85 0.66 Slightly lower Opportunistic pathogens g_unclassified_Planctomycetota 1.42 4.96 Significant increase Unclassified member of the phylum Planicillium (the phylum containing anaerobic ammonia oxidizing bacteria). g_unclassified_Pyrimononadaceae 4.57 11.76 Significant increase Unclassified member of the family Pyrimononadaceae (belonging to the phylum Bacteroidetes). Others 9.46 14.85 rise - Experiment Example 1: Effect Detection; like Figure 2 As shown, the left side contains NH4. + -N, NO2 - -N, NO3 - -N concentration, current density on the right, and total operating time (0-30 days) on the horizontal axis; after the device stabilizes, the NO2 in the influent is gradually reduced under an applied voltage of 0.6V. - The ammonia nitrogen concentration dropped to 0 by day 6. The results showed that the ammonia nitrogen removal efficiency of the unit remained unaffected and stable. On day 23.5, ATU (a nitrification and denitrification microbial inhibitor) was added to the influent, and the ammonia nitrogen removal performance of the unit still did not decline. This indicates that in this system, ammonia nitrogen removal is mainly accomplished by anaerobic ammonium oxidation (ANAMMOX), and nitrification and denitrification processes do not play a major role.

[0030] like Figure 3 As shown, after the device had been running for 32-35 days, the system was opened and water was introduced, but no additional NO2 was added. - -N, discovered NH4 + The inability to remove -N underwent the test, highlighting the importance of applied voltage for ammonia nitrogen removal in the system. like Figure 4 As shown, after the system resumed closed-loop operation and stabilized, NO2 was added back to the feed water on day 45.5. - -N. At this time, NH4 +The removal performance of -N remained unchanged, but the system current density gradually decreased to zero. This indicates that the electrode-dependent anaerobic ammonium oxidation system preferentially utilizes NO2 in the influent. - -N, thereby gradually reducing dependence on applied voltage.

[0031] like Figure 5 As shown, after the system stabilized again, the device was autoclaved on day 57.5, and then the circuit was reconnected. The results showed that the system effectively controlled NH4. + The removal rate of -N and the current density both dropped to zero, indicating that the denitrification function of this system depends on the activity of anaerobic ammonia-oxidizing microorganisms attached to the anode surface.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode-dependent anaerobic ammonium oxidation process, characterized in that, Includes the following steps: S1: Inoculate the initial biomass into the membrane bioreactor and continuously add an inorganic culture medium containing ammonia nitrogen into the membrane bioreactor; S2: Select a single-chamber or double-chamber microbial electrolysis cell and configure a three-electrode system: the working anode electrode is selected from graphite rod, carbon felt or carbon cloth, the cathode electrode is selected from platinum mesh or graphite rod, and the reference electrode is selected from Ag / AgCl electrode. S3: Take the inorganic culture medium from S1, dissolve it, boil it, and pass a mixture of N2 and CO2 gas to remove dissolved oxygen. Cool it, add KHCO3 to dissolve it, and adjust the pH of the culture medium to 7.0-7.5 to obtain the inorganic culture medium. S4: Inject the sterile culture medium from S3 into the sealed electrolytic cell, set the working electrode potential to 0.6V, and continuously monitor until no obvious current is generated and NH4+ is released. + Concentration change rate ≤ 5%; S5: Inoculate the anaerobic ammonia-oxidizing bacteria enriched in S1 into the electrolytic cell that has passed the verification in S4, adjust the bacterial inoculation concentration, and add NH4+ to the electrolytic cell. + The inorganic culture medium was maintained at the same temperature and stirring conditions as in S1, and monitoring was continued until NH4 was reached. + Removal rate ≥90% and biofilm thickness ≥10μm; S6: Initiate electron acceptor switching acclimatization to gradually reduce NO2 in the influent. - Concentration, until the concentration reaches 0; S7: Continuously introduce NO2-free gas into the electrolytic cell. - NH4+ containing nitrates and exogenous organic carbon + Water intake, maintaining a working electrode potential of 0.6V, operating temperature of 20-36℃, and pH of 7.0-7.5; S8: Collect the gas produced by the reaction.

2. The electrode-dependent anaerobic ammonium oxidation process according to claim 1, characterized in that, In S1, the dry weight concentration of the biomass is 10-50 g / L, the proportion of anaerobic ammonia oxidizing bacteria is ≥60%, the proportion of attached heterotrophic bacteria is ≤10%, and the proportion of inorganic particles is 30-40%.

3. The electrode-dependent anaerobic ammonium oxidation process according to claim 1, characterized in that, The operating conditions of the membrane bioreactor are pH 7.5-8.0, culture temperature 20-36℃, and stirring speed 100-200 r / min.

4. The electrode-dependent anaerobic ammonium oxidation process according to claim 1, characterized in that, The inorganic culture medium contains CaCl2 100-120 mg / L, MgSO4 300-400 mg / L, KH2PO4 30-50 mg / L, KHCO3 400-600 mg / L and trace element solution; The trace element solution contains 100-200 μM FeSO4·7H2O, 10-30 μM MnCl2·4H2O, 5-15 μM ZnSO4·7H2O, 1-5 μM CuSO4·5H2O, 1-5 μM CoCl2·6H2O, and 1-5 μM Na2MoO4·2H2O.

5. The electrode-dependent anaerobic ammonium oxidation process according to claim 1, characterized in that, In S2, the working volume of a single chamber is 300-500 mL, and the working volume of each chamber in a dual-chamber setup is 200-300 mL.

6. The electrode-dependent anaerobic ammonium oxidation process according to claim 1, characterized in that, In S2, the acid washing and water washing steps for the working electrode and the counter electrode are as follows: first, soak in 1-5 mol / L hydrochloric acid solution for 12-24 hours, stirring once every 4-6 hours during the soaking period at a stirring rate of 50-100 r / min; then rinse with deionized water until the pH of the rinsing solution is 6.5-7.5; and then purge with nitrogen for 30-60 minutes.

7. The electrode-dependent anaerobic ammonium oxidation process according to claim 1, characterized in that, In S5, the bacterial inoculum concentration was adjusted to 0.1-0.9 mg-protein / mL. -1 .

8. The electrode-dependent anaerobic ammonium oxidation process according to claim 1, characterized in that, S6 specifically involves: initiating electron acceptor switching acclimatization, reducing NO2 in the influent each time. - Maintain NH4 concentration at 20%-30%. + With the concentration kept constant, each concentration gradient was run for 3-7 days, during which NH4 was monitored. + Removal rate, NO2 - The residual amount and current changes were recorded using a potentiostat, and the above process for NO2 was repeated. - Concentration reduction operation until NO2 in the influent... - The concentration dropped below the detection limit, and was observed to be related to NH4 within three consecutive monitoring periods. + Consumption is positively correlated with the generation of stable current.

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