Anaerobic ammonia oxidation-photoelectric denitrification deep nitrogen removal method

Abstract

The invention belongs to the technical field of sewage treatment, and particularly relates to an anaerobic ammonia oxidation-photoelectric denitrification deep nitrogen removal method. The method comprises the following steps: firstly, adopting a double-chamber reactor; introducing part of sewage into the cathode chamber, carrying out Anammox reaction under a dark state condition to remove ammonia nitrogen and part of nitrite nitrogen, and synchronously generating nitrate nitrogen; turning on a light source to irradiate the anode chamber, exciting photo-induced electrons by a photosensitizer, transmitting the photo-induced electrons to the cathode chamber through an external circuit, and driving the sulfur autotrophic denitrification sludge to reduce residual nitrite nitrogen and nitrate nitrogen generated by Anammox; the total nitrogen removal rate is close to 100%. According to the invention, photo-induced electrons are used as the only denitrification electron donor, so that the addition of a carbon source / sulfide is thoroughly avoided, and the risk of secondary pollution is eliminated. The method is suitable for green low-carbon deep treatment of sludge digestion liquid and pharmaceutical wastewater high-ammonia-nitrogen low-carbon-nitrogen-ratio sewage.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a deep nitrogen removal method using anaerobic ammonia oxidation-photoelectric denitrification. Background Technology

[0002] Wastewater denitrification is crucial for preventing eutrophication. Anammox, an ammonia oxidation process, has attracted considerable attention due to its lack of organic carbon sources, low sludge production, and low energy consumption. However, its reaction stoichiometry leads to approximately 11% nitrate nitrogen accumulation, limiting the total nitrogen removal rate (theoretical maximum 89%). To address this issue, existing technologies mainly suffer from the following limitations: Traditional autotrophic or heterotrophic denitrification coupling technologies introduce sulfides, zero-valent iron, iron minerals, hydrogen, or other organic carbon sources, leading to increased operating costs, sulfate accumulation, or secondary pollution risks, which contradicts the low-carbon original intention of the Anammox process.

[0003] As described in invention patent CN111573834A, bioelectrochemical systems drive denitrification through electrode reactions, but still rely on the oxidation of organic matter at the anode to generate electrons. Essentially, they still involve the consumption of organic matter, and the systems are complex, requiring high precision in electrode potential control, and are susceptible to risks such as anode chamber acidification. While existing research on photoelectric denitrification has revealed the photoelectric potential of some microbial communities and natural substances, its photoelectron yield is low, its stability is poor, and research remains focused on single denitrification processes, without effective and stable system integration with Anammox.

[0004] Therefore, current technology lacks a solution that can fully utilize light energy as the sole external energy input and achieve efficient and stable removal of endogenous nitrates in the Anammox system. Summary of the Invention

[0005] To address the problems existing in the current technology, this application provides the following technical solution: This invention provides a deep nitrogen removal method using anaerobic ammonia oxidation-photoelectric denitrification, comprising the following steps: S11: Prepare the anode and cathode respectively; the cathode is a carbon material with composite functional sludge embedded and fixed; the composite functional sludge is embedded and fixed by conductive hydrogel, and the composite functional sludge includes anaerobic ammonia oxidation sludge and sulfur autotrophic denitrification sludge; S12: The anode and cathode are connected by an electrical circuit and placed in the anode chamber and cathode chamber respectively; the anode chamber and cathode chamber are isolated by a proton membrane; S13: An aqueous solution containing a hole scavenger is added to the anode chamber, and wastewater is added to the cathode chamber for anaerobic ammonia oxidation. The wastewater added to the cathode chamber in this invention is pretreated wastewater that has undergone nitrification, and mainly contains ammonia nitrogen (NH4). +-N) and nitrite nitrogen (NO2) - -N), and the concentration ratio of nitrite nitrogen to ammonia nitrogen (NO2) - -N / NH4 + -N) is 1.3-1.5; S14: When the nitrate ion concentration in the wastewater in the cathode chamber is 10-15 mg / L or the ammonium ion concentration is 0, the anode chamber is irradiated with a light source to carry out photoelectric denitrification reaction, and the effluent from the cathode chamber is discharged, thus completing the anaerobic ammonia oxidation-photoelectric denitrification deep denitrification method.

[0006] Preferably, the anode is a titanium sheet supported on a graphitic carbon nitride / titanium dioxide (g-C3N4 / TiO2) heterojunction.

[0007] Preferably, the anaerobic ammonia oxidation sludge is obtained by adding dewatered sludge from a wastewater treatment plant to water containing ammonia nitrogen and nitrite nitrogen for cultivation and acclimatization.

[0008] Preferably, the sulfur-autotrophic denitrifying sludge is obtained by adding dewatered sludge from a wastewater treatment plant to water containing sulfides and nitrate nitrogen for cultivation and acclimatization.

[0009] Furthermore, the preparation method of the graphitic carbon nitride / titanium dioxide heterojunction is as follows: graphitic carbon nitride (g-C3N4) and titanium dioxide are mixed in alcohol and then subjected to hydrothermal reaction, followed by drying.

[0010] Specifically, the drying method involves centrifugal washing followed by drying at 60°C.

[0011] Furthermore, the conditions for the hydrothermal reaction are: pH value of 8.5-9.5, temperature of 140-160℃, and time of 5-7h.

[0012] Specifically, the pH value is adjusted by adding ammonia.

[0013] Specifically, the alcohol is ethanol.

[0014] Specifically, the mixing method involves ultrasonic treatment for 1 hour.

[0015] Specifically, the mass ratio of the graphitic carbon nitride to titanium dioxide is 1:3-4.

[0016] Preferably, the cathode is prepared by: S21: An aqueous solution containing sodium alginate and polyvinyl alcohol is mixed with water containing anaerobic ammonia oxidation sludge and sulfur autotrophic denitrification sludge, and then aniline and graphene are added to obtain a hydrogel slurry. S22: The hydrogel slurry is coated onto a carbon material and then sequentially immersed in an aqueous solution containing calcium chloride and boric acid and an aqueous solution containing potassium dihydrogen phosphite to obtain a crosslinked composite material. S23: The crosslinking composite material is added to an acidic aqueous solution containing an oxidant and reacted in an ice bath to obtain the cathode.

[0017] Furthermore, the mass ratio of sodium alginate to polyvinyl alcohol is 2:5.

[0018] Furthermore, the oxidant is ammonium persulfate (APS).

[0019] Furthermore, in the aqueous solution containing calcium chloride and boric acid, the concentration of calcium chloride is 1 wt%, the concentration of boric acid is saturated, and the concentration of potassium dihydrogen phosphite in the aqueous solution is 0.5 M.

[0020] Furthermore, the acidic aqueous solution is an aqueous solution containing potassium dihydrogen phosphite, with a pH value of 4-5 and a potassium dihydrogen phosphite concentration of 0.5 M.

[0021] Furthermore, in step S23, the temperature of the ice bath reaction is 0-5℃, and the time is 0.4-0.6 h.

[0022] Furthermore, in step S23, the ice bath reaction is followed by repeated washing with water.

[0023] Preferably, the proton exchange membrane is a sulfonated polyether ether ketone (SPEEK) membrane or a Nafion membrane.

[0024] Preferably, the anode chamber and cathode chamber are made of transparent acrylic or glass.

[0025] Preferably, the carbon material is a carbon felt or a carbon brush.

[0026] Preferably, in step S13, the anaerobic ammonia oxidation reaction is in a dark-state Anammox-dominated phase, specifically by introducing a portion of the nitrified effluent (NO2) into the cathode chamber under dark conditions. - -N / NH4 + (The -N concentration ratio is not less than 1.3) to perform a conventional Anammox reaction. An online monitoring system tracks nitrogen changes in real time.

[0027] Preferably, in step S14, when the photoelectric denitrification reaction is triggered, the effect is as follows: when NO3 is detected... - When the concentration accumulates to a set threshold (e.g., 10-15 mg / L) or NH4 + When the power is depleted, the intelligent control system automatically turns on the main light source.

[0028] Specifically, in step S14, when the photoelectric denitrification reaction is triggered, the main light source excites the photoanode to generate high-density photogenerated electrons, and the holes are consumed by a hole scavenger (such as sodium lactate). The photogenerated electrons migrate to the cathode via the external circuit and are preferentially utilized by the sulfur autotrophic denitrification sludge immobilized on the cathode surface, thereby converting NO3... - Reduced to NO2 - Or it can be directly reduced to N2. The NO2 produced by anaerobic ammonia oxidation sludge through photoelectric denitrification... - , with the remaining NH4 + The reaction generates nitrogen gas and nitrate nitrogen, forming a highly efficient internal cycle of "nitrate nitrogen-nitrite nitrogen-nitrogen gas" until the total nitrogen in the water is almost completely removed.

[0029] Preferably, in step S14, the light source irradiating the anode chamber is a 360-420 nm light source with a light intensity of 45-55 mW / cm². 2 .

[0030] Preferably, in step S14, a 600-750 nm light source is used to irradiate the cathode chamber to maintain the cathode chamber at 25-30°C.

[0031] Specifically, when the cathode chamber water temperature is detected to be low or above a set threshold (e.g., 25-30℃), the intelligent control system automatically turns on the auxiliary light source switch. Infrared light is absorbed by materials such as graphene to generate a photothermal effect, which gradually increases the local temperature and ensures the metabolic activity of the sludge.

[0032] Preferably, the anode chamber and the cathode chamber are further provided with a stirrer, and the stirring speed is 150-250 rpm.

[0033] Preferably, the cavitation scavenger is sodium lactate at a concentration of 0.6 g / L.

[0034] Preferably, in step S14, when the total nitrogen concentration drops to a set value (which can be set according to the wastewater discharge standard, such as 3-5 mg / L), all light sources are turned off, and the system is allowed to settle and then discharged.

[0035] The technical solution of the present invention has the following advantages compared with the prior art: This invention provides an advanced system for anaerobic ammonia oxidation (Anammox) coupled with photogenerated electron-driven denitrification, integrating spectral synergistic excitation, functional sludge encapsulation and colonization, conductive hydrogel-enhanced electron transfer, and intelligent light control. This invention aims to overcome the shortcomings of existing technologies by creatively coupling Anammox with photogenerated electron-driven sludge denitrification, utilizing light energy as a clean electron source, and enhancing electron transfer and temperature control through photothermal conductive materials. This provides a deep nitrogen removal system and method for wastewater with near 100% nitrogen removal efficiency, requiring no chemical additives, stable operation, and low energy consumption. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the reactor of the present invention.

[0037] Explanation of reference numerals in the attached diagram: 1-Anode chamber, 2-Cathode chamber, 3-Circuit, 4-Proton exchange membrane, 5-Anode, 6-Cathode, 7-Stirrer, 8-Main light source, 9-Auxiliary light source, 10-Multi-parameter electrode, 11-Light source control system. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0039] Example 1: Construction of the reaction device like Figure 1 As shown, the reactor in this invention is a partitioned coupled reactor, comprising an anode chamber 1 and a cathode chamber 2 made of glass. The anode chamber 1 and cathode chamber 2 are separated by a proton exchange membrane 4 made of perfluorosulfonic acid (Nafion) membrane. A cathode 6 is provided in the cathode chamber 2, and an anode 5 is provided in the anode chamber 1. The cathode 6 and anode 5 are connected by an external circuit 3. A stirrer 7 is also provided at the bottom of the anode chamber 1 and cathode chamber 2 for mixing the liquids therein.

[0040] Anode 5 is a photoanode loaded with a graphitic carbon nitride / titanium dioxide heterostructure, which was prepared in-house. The preparation method is as follows: 1 g of g-C3N4 and 3 g of TiO2 were dispersed in 100 mL of ethanol at a mass ratio of 1:3, ultrasonically treated for 1 hour, ammonia was added to adjust the pH to 9, hydrothermal reaction was carried out at 150℃ for 6 hours, centrifuged and washed, and dried at about 60℃ to obtain g-C3N4 / TiO2 heterostructure composite material.

[0041] The titanium sheet was polished with metallographic sandpaper and then ultrasonicated for 15 minutes each in acetone, anhydrous ethanol, and deionized water to remove oil and impurities. A photoanode was then fabricated by electrodeposition of the g-C3N4 / TiO2 heterojunction composite material onto the titanium sheet. The detailed fabrication method is as follows: (1) Take 100 mL of deionized water and 100 mL of anhydrous ethanol and mix them evenly to prepare a mixed solvent; (2) Weigh 0.03 g of Mg(NO3)2·6H2O and dissolve it in a mixed solvent; (3) Add 0.15g of g-C3N4 / TiO2 powder; (4) Using a probe-type ultrasonic instrument, ultrasonically disperse the solutions obtained in steps (1) to (3) in an ice-water bath for 30-60 minutes. Power 100W, work for 3 seconds, pause for 3 seconds to prevent overheating. Continue until a homogeneous, stable suspension without obvious sedimentation is formed; (5) Construct a three-electrode system in the order of “working electrode | electrolyte | counter electrode | reference electrode”. Fix the pretreated titanium sheet as the working electrode, ensuring that the surface to be deposited is completely immersed in the suspension. Place the counter electrode (platinum sheet) and the reference electrode on both sides of the titanium sheet, about 1-2 cm apart.

[0042] (6) Use an electrochemical workstation to provide a stable deposition voltage, set the deposition potential between -1.0 V and -1.5 V (vs. SCE / AgAgCl), and the deposition time is 30 minutes (the longer the deposition time, the thicker the film). Throughout the deposition process, use a magnetic stirrer to continuously stir the suspension at a low speed (200 rpm) to ensure uniform particle distribution and prevent sedimentation.

[0043] (7) After deposition, slowly remove the titanium sheet and gently rinse the surface with deionized water to remove loose particles that are physically adsorbed. Then place it flat in a petri dish and let it air dry at room temperature for 12 hours, and then transfer it to a 60°C oven to dry for 2 hours to stabilize the film structure.

[0044] (8) Place the dried electrode into a muffle furnace and heat it to 300°C at a rate of 4°C / min in air atmosphere. Hold it at that temperature for 2 hours and then cool it to room temperature with the furnace.

[0045] The cathode 6 is a carbon brush whose surface is immobilized by a bio-affinity conductive hydrogel. The composite sludge is a co-immobilization system of anaerobic ammonia oxidation sludge and sulfur autotrophic denitrification sludge.

[0046] This invention uses dewatered sludge obtained from the anaerobic reactor of the Suzhou Fuxinghe Water Treatment Plant as seed sludge, and then cultivates and acclimatizes it: ① Add seed sludge to water (at this time, the amount of sludge inoculated is 12 g / L MLSS), and add ammonium chloride (300 mg / L) and sodium nitrite (400 mg / L) to the water. Cultivate and acclimate for 90 days, and effluent will yield anaerobic ammonia oxidation sludge; ② Add seed sludge to water (at this time, the amount of sludge inoculated is 12 g / L MLSS), and add sodium sulfide (75 mg / L) and sodium nitrate (75 mg / L) to the water for cultivation and acclimatization for 90 days. The effluent yields sulfur autotrophic denitrification sludge.

[0047] The preparation method of cathode 6 is as follows: (1) The anaerobic ammonia oxidation sludge and sulfur autotrophic denitrification sludge enriched and cultured were mixed to form a uniform composite functional sludge solution of 100 mL. The volatile suspended solids concentration (MLVSS) of the mixed solution was 2.4 g / L. The mixed sludge solution was washed three times with phosphate buffer solution (PBS) to remove residual matrix and impurities, and the pretreated sludge was obtained.

[0048] (2) Weigh 2 g sodium alginate (SA) and 5 g polyvinyl alcohol (PVA), dissolve them in 100 mL of deionized water, heat in a 60°C water bath and stir mechanically until completely dissolved to form a homogeneous and transparent solution, and cool naturally to room temperature (25°C).

[0049] (3) Mix 50 mL of pretreated sludge with an equal volume of SA-PVA mixed solution and stir thoroughly to form a uniform sludge hydrogel solution.

[0050] (4) Introduce conductive monomers, that is, add 3.7 mL of aniline standard solution (1 mol / L) and 0.5 g of graphene to the above sludge hydrogel solution and stir continuously to make the conductive monomers uniformly dispersed in the gel-sludge system.

[0051] (5) Immerse the carbon brush into the sludge hydrogel slurry containing aniline prepared in the second step, ensuring that the slurry fully wets the carbon brush fibers. Slowly lift the carbon brush to remove excess slurry, so that a uniform coating is formed on the carbon brush surface.

[0052] (6) Immediately immerse the coated carbon brush in a saturated boric acid solution containing 1% CaCl2. Sodium alginate and PVA will rapidly undergo ionic cross-linking and complexation in this solution to form a preliminary stable gel layer, fixing the sludge to the carbon brush surface. After removal, immerse it in a 0.5 M KH2PO4 solution for further stabilization.

[0053] (7) Finally, in-situ polymerization of aniline is carried out: The carbon brush with the preliminary gel layer is immersed in an aqueous solution (pH 5) containing 1 g of oxidant APS and 0.5 M potassium dihydrogen phosphate. The reaction is carried out under ice bath conditions (0°C) for 0.5 hours, so that aniline is polymerized inside the gel network and on the surface of the carbon brush fiber to form polyaniline, thereby giving the gel layer conductivity.

[0054] (8) After polymerization, rinse the electrode repeatedly with deionized water until the water becomes clear to remove residual reagents and byproducts.

[0055] Figure 1In this invention, the reactor further includes a spectral synergistic light source system, comprising a main light source 8 and an auxiliary light source 9. The main light source 8 has a wavelength of 360-420 nm and is used to excite the photosensitizer; the auxiliary light source 9 has a wavelength of 600-750 nm, i.e., red or near-infrared light, and is used to irradiate the cathode chamber 2, simultaneously generating a photothermal effect to promote the metabolic activity of the sludge. The main light source 8 is used to irradiate the light source inside the anode chamber 1, and the auxiliary light source 9 is used to irradiate the light source inside the cathode chamber 2.

[0056] The reactor also includes an intelligent control system, namely a light source control system 11, which includes a multi-parameter electrode 10 located inside the cathode chamber 2, and also integrates an external online water quality sensor (NH4). + NO3 - The system uses sensors for total nitrogen (TN), pH / ORP, temperature, and light intensity to achieve on-demand illumination (the photoelectric denitrification stage is triggered by anodic illumination based on nitrate concentration, and the cathode-assisted illumination is adjusted based on temperature) and adaptive light intensity adjustment.

[0057] Example 2: Using carbon brushes with gel-encapsulated sludge as cathodes to treat simulated nitrogen-containing wastewater Wastewater treatment is carried out using the reaction apparatus in Example 1, as follows: System parameters: Total reactor volume 1.0 L. Photoanode is g-C3N4 / TiO2 composite electrode (g-C3N4 to TiO2 mass ratio 1:3). Cathode consists of anaerobic ammonia oxidation sludge and sulfur autotrophic denitrification sludge, which are embedded in gel and fixed on the carbon brush electrode surface. Main light source is a 365 nm LED array (maximum luminous intensity 50 mW / cm²), and auxiliary light source is a 630 nm LED array.

[0058] During operation, a portion of the nitrified effluent (NO2) is first introduced into the cathode chamber under dark conditions. - -N / NH4 + (With a nitrogen concentration ratio of not less than 1.3), 0.6 g / L sodium lactate was added to the anode chamber for a standard Anammox reaction. An online monitoring system tracked nitrogen changes in real time for 8 hours. Subsequently, the light source control system automatically activated the main light source to irradiate anode chamber 5 and the auxiliary light source to irradiate cathode chamber 2 for 40 hours.

[0059] Operating results: In the influent NH4 + -N concentration was 120 mg / L, NO2 - Under a -N concentration of 160 mg / L, the system achieved efficient removal of total nitrogen after approximately 50 hours of continuous operation. The specific operating process is as follows: 0-8 h is the dark-state Anammox reaction period, during which NH4+... + -N and NO2 --N was almost completely removed; the photo-denitrification period was 8-48 hours, lasting approximately 40 hours, successfully removing approximately 26 mg / L NO3 produced by the dark-state Anammox reaction. - -N; the final effluent total nitrogen concentration after sedimentation is less than 1.0 mg / L, the removal rate is close to 100%, and no organic carbon source or sulfide is added during the entire operation.

[0060] Compared to Comparative Example 1, this embodiment uses a carbon brush with gel-embedded sludge as the cathode, which shortens the reaction time by about 56% and greatly improves the reaction rate.

[0061] Comparative Example 1: Carbon brushes without gel-encapsulated sludge were used as cathodes to treat simulated nitrogen-containing wastewater. The apparatus used is the same as in Embodiment 1, and the operating method is the same as in Embodiment 2, with the following differences: System parameters: Total reactor volume 1.0 L. Photoanode is a g-C3N4 / TiO2 composite electrode (g-C3N4 to TiO2 mass ratio 1:3). Cathode consists of anaerobic ammonia oxidation sludge and sulfur autotrophic denitrification sludge, the mixed sludge naturally adhering to the carbon brush electrode surface after stirring. Main light source is a 365 nm LED array (maximum luminous intensity 50 mW / cm²), auxiliary light source is a 630 nm LED array.

[0062] Operating results: In the influent NH4 + -N concentration was 120 mg / L, NO2 - Under a -N concentration of 160 mg / L, the system achieved efficient removal of total nitrogen after approximately 113 hours of continuous operation. The specific operating procedure is as follows: 0-10 h was the dark-state Anammox reaction period, lasting 10 hours, during which NH4+... + -N and NO2 - -N was almost completely removed; the photo-denitrification period was 10-110 hours, lasting approximately 100 hours, during which approximately 23 mg / L of NO3 produced by the dark-state Anammox reaction was successfully removed. - -N; the final effluent total nitrogen concentration after sedimentation is less than 1.0 mg / L, the removal rate is close to 100%, and no organic carbon source or sulfide is added during the entire operation.

[0063] Comparative Example 2: Denitrification performance test without photosensitive electrode The apparatus used is the same as in Embodiment 1, and the operating method is the same as in Embodiment 2, with the following differences: To verify the key role of photoelectric denitrification in this system, a control system without a photosensitive electrode was set up in this embodiment, and the other conditions were the same as in Example 1.

[0064] System parameters: Total reactor volume 1.0 L. The anode is an inert electrode (carbon felt) without any photosensitive material (g-C3N4 and TiO2). The cathode is the same as in Example 2. The main light source system is kept off.

[0065] Operation and Results: After completing the same dark-state Anammox reaction as in Example 1, approximately 20 mg / L of NO3 accumulated in the system. - -N. At this stage, due to the lack of external photogenerated electrons provided by the photoanode, nitrogen removal relies solely on the endogenous denitrification capacity of the cathode sludge. Continuous monitoring shows that NO3... - The removal rate of -N was extremely slow, only 1.2 ± 0.6 mg / L / day. Given that this rate was insufficient for the practical requirements of efficient nitrogen removal, the operation was halted after approximately 150 hours.

[0066] The results show that without the drive of the photoelectric denitrification system, it is difficult to achieve efficient and rapid removal of total nitrogen by relying solely on the spontaneous metabolism of sludge, thus confirming the necessity and superiority of introducing photosensitive electrodes to start photoelectric denitrification.

[0067] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for deep denitrification by anaerobic ammonia oxidation-photoelectrochemical denitrification, characterized in that, The method comprises the following steps: S11: separately preparing an anode and a cathode; the cathode is a carbon material embedded with a composite functional sludge; the composite functional sludge comprises anaerobic ammonia oxidation sludge and sulfur autotrophic denitrification sludge, and is embedded and fixed by a conductive hydrogel; S12: connecting the anode and the cathode through an electric circuit and then placing them in an anode chamber and a cathode chamber respectively; the anode chamber and the cathode chamber are separated by a proton membrane; S13: adding an aqueous solution containing a hole scavenger to the anode chamber and adding sewage to the cathode chamber, and then performing an anaerobic ammonia oxidation reaction under light shielding conditions; S14: when the nitrate ion concentration of the sewage in the cathode chamber is 10-15 mg / L or the ammonium ion concentration is 0, irradiating the anode chamber with a light source, performing a photoelectric denitrification reaction, and then discharging water from the cathode chamber, thereby completing the anaerobic ammonia oxidation-photoelectric denitrification deep nitrogen removal method.

2. The method according to claim 1, wherein the anaerobic ammonia oxidation-photoelectrochemical denitrification process is carried out in the presence of a light source. The anode is a titanium sheet loaded with a graphite phase carbon nitride / titanium dioxide heterojunction.

3. The ANAMMOX-photoelectrodenitrification advanced nitrogen removal process according to claim 2, characterized in that, The preparation method of the graphite phase carbon nitride / titanium dioxide heterojunction is: mixing graphite phase carbon nitride and titanium dioxide in alcohol, then performing a hydrothermal reaction, and drying to obtain the graphite phase carbon nitride / titanium dioxide heterojunction.

4. The method of claim 1, wherein the anaerobic ammonia oxidation-photoelectrochemical denitrification advanced nitrogen removal process is characterized by, The anaerobic ammonia oxidation sludge is obtained by adding dewatered sludge from a sewage plant to water containing ammonia nitrogen and nitrite nitrogen and then culturing and domesticating the sludge.

5. The method of claim 1, wherein the anaerobic ammonia oxidation-photoelectrochemical denitrification advanced nitrogen removal process is characterized by, The sulfur autotrophic denitrification sludge is obtained by adding dewatered sludge from a sewage plant to water containing sulfide and nitrate nitrogen and then culturing and domesticating the sludge.

6. The method of claim 1, wherein the anaerobic ammonia oxidation-photoelectrochemical denitrification advanced nitrogen removal process is characterized by, The preparation method of the cathode is: S21: mixing an aqueous solution containing sodium alginate and polyvinyl alcohol with water containing anaerobic ammonia oxidation sludge and sulfur autotrophic denitrification sludge, then adding aniline and graphene to obtain a hydrogel slurry; S22: coating the hydrogel slurry on a carbon material, and then sequentially immersing the carbon material in an aqueous solution containing calcium chloride and boric acid and an aqueous solution containing potassium dihydrogen phosphite to obtain a cross-linked complex material; S23: adding the cross-linked complex material to an acidic aqueous solution containing an oxidizing agent, and then performing an ice bath reaction to obtain the cathode.

7. The method of claim 1, wherein the anaerobic ammonia oxidation-photoelectrochemical denitrification advanced nitrogen removal process is characterized by, In the step S14, the light source irradiating the anode chamber is a light source of 360-420 nm, and the light intensity is 45-55 mW / cm 2 .

8. The method of claim 1, wherein the anaerobic ammonia oxidation-photoelectrochemical denitrification advanced nitrogen removal process is characterized by, In the step S14, a light source with a wavelength of 600-750 nm is used to irradiate the cathode chamber, so that the cathode chamber is maintained at 25-30℃.

9. The method of claim 1, wherein the anaerobic ammonia oxidation-photoelectrochemical denitrification advanced nitrogen removal process is characterized by, The anode chamber and the cathode chamber are also provided with stirrers, and the stirring speed is 150-250 rpm.

10. The method of claim 1, wherein the anaerobic ammonia oxidation-photoelectrochemical denitrification advanced nitrogen removal process is characterized by, The hole scavenger is sodium lactate.

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