Device and method for coupling Fenton residual iron sludge with iron ammoxidation and anaerobic ammoxidation

Abstract

The invention discloses a device and a method for coupling Fenton residual iron sludge with iron ammoxidation and anaerobic ammoxidation. The device comprises a water inlet tank, a five-section reactor, a secondary sedimentation tank and a Fenton reactor which are connected in sequence. According to the method, iron sludge (containing ferric iron) generated by a Fenton reactor flows back to a five-section reactor to realize enrichment of iron ammonium oxidation flora in activated sludge, nitrite and nitrate nitrogen generated by iron ammonium oxidation are directly or indirectly utilized by anaerobic ammonium oxidation bacteria on filler, and anaerobic ammonium oxidation reaction is performed; nitrate nitrogen generated in the aerobic zone can be subjected to short-cut denitrification anaerobic ammonia oxidation reaction by utilizing a carbon source and ammonia nitrogen in inlet water for denitrification. According to the method, reduction and innocent treatment of the Fenton iron sludge are realized, and refractory organic matters are removed while high nitrogen and phosphorus removal efficiency of the industrial wastewater is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage purification, and relates to the denitrification and phosphorus removal of municipal sewage, and in particular to a device and method for realizing the denitrification and phosphorus removal of industrial wastewater or industrial wastewater containing part of municipal sewage by Fenton residual iron sludge coupled iron ammonia oxidation or anaerobic ammonia oxidation. Background Art

[0002] The Fenton reaction is an advanced oxidation technology used in wastewater treatment. It uses the strong oxidizing property of hydroxyl radicals to degrade and remove organic pollutants in water. This reaction is usually carried out under acidic conditions and involves hydrogen peroxide and ferrous ions (Fe 2+ )’s reaction.

[0003] In the Fenton reaction, hydrogen peroxide reacts with ferrous ions to generate hydroxyl radicals, which can react with organic pollutants to decompose them into smaller inorganic substances. This advanced oxidation process is efficient, rapid, broad-spectrum and environmentally friendly, and is suitable for treating a variety of organic substances, including wastewater containing organic substances such as benzene, phenol and / or formaldehyde.

[0004] The Fenton reaction is commonly used in industrial wastewater treatment and environmental remediation, and can effectively degrade and remove difficult-to-degrade organic pollutants.

[0005] Feammox technology is a newly discovered autotrophic biological denitrification technology. This technology has the advantages of no need for organic carbon source, low sludge production, and less greenhouse gas, and provides a new denitrification pathway for the sewage treatment system. The Feammox reaction can convert trivalent iron salts and ammonia nitrogen into ferrous ions, nitrites and nitrates. The Feammox reaction can remove part of the ammonia nitrogen and convert it into nitrite and nitrate nitrogen.

[0006] The oxygen-ammonia oxidation reaction can convert ammonia nitrogen and nitrite into nitrogen gas in the presence of anaerobic ammonium-oxidizing bacteria. The reaction does not require an organic carbon source. The application of this technology in sewage treatment is a research hotspot in the environmental field.

[0007] The iron sludge produced by the Fenton reaction is used as a medium to provide the reaction substrate iron salt for the iron ammonia oxidation to react with the ammonia nitrogen in the influent. The product of the iron ammonia oxidation can provide nitrite, one of the reaction substrates, for the anaerobic ammonia oxidation reaction, and react with the remaining ammonia nitrogen in the influent for anaerobic ammonia oxidation. The ferrous ions generated during the iron ammonia oxidation process can react with phosphate and remove phosphorus from the system at the same time.

[0008] In the process of industrial wastewater treatment, the treatment of refractory organic matter is carried out through advanced oxidation technology such as Fenton. The Fenton process will produce iron sludge, which is a hazardous waste with high treatment costs and difficulty. The iron-ammonia oxidation technology can achieve the reduction and harmlessness of Fenton iron sludge, achieve the stable removal of refractory organic matter in industrial wastewater, and ensure the denitrification and phosphorus removal effect of industrial wastewater. Summary of the invention

[0009] In order to target the unstable source of substrate for anaerobic ammonia oxidation bacteria in the continuous flow five-stage water treatment process, the difficulty in treating the iron mud of the Fenton treatment product of industrial wastewater organic matter, and the difficulty in maintaining iron ammonia oxidation in the system, on the basis of the presence of Fenton deep treatment of refractory organic matter in industrial wastewater, the present invention combines iron ammonia oxidation with the waste generated by the anaerobic ammonia oxidation process and the Fenton technology, and by adding the iron mud produced by the Fenton reaction into the biochemical reaction tank, the iron ammonia oxidation is strengthened while enhancing the functional effect of anaerobic ammonia oxidation, further providing a stable nitrite substrate for anaerobic ammonia oxidation bacteria, improving the denitrification contribution rate of anaerobic ammonia oxidation in industrial wastewater treatment, and playing a good role in phosphorus removal. Provides a stable and efficient new technology for industrial wastewater treatment, promotes the promotion and application of anaerobic ammonia oxidation process in sewage treatment, and reduces hazardous wastes such as iron mud. The present invention provides a theoretical basis and technical support for deep treatment of industrial wastewater, energy saving and consumption reduction, and iron mud treatment and disposal, and has important application value.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] The present invention first provides a device for coupling iron-ammonia oxidation and anaerobic ammonia oxidation by Fenton residual iron sludge, the device comprising an inlet tank, a five-stage reactor, a secondary sedimentation tank and a Fenton reactor connected in sequence; wherein the five-stage reactor comprises an anaerobic zone, an anoxic zone 1, an aerobic zone 1, an aerobic zone 2, anoxic zone 2, anoxic zone 3 and aerobic zone 3; the iron sludge produced by the Fenton reactor is refluxed to the anaerobic zone and the anoxic zone 2 via a pipeline, the sludge in the secondary sedimentation tank is refluxed to the anaerobic zone, and the aerobic zone 2 and the anoxic zone 1 are refluxed.

[0012] As a preferred solution of the present invention, aerators are arranged at the bottom of the aerobic zone 1, aerobic zone 2 and aerobic zone 3; and an air blowing system is also included, and the aerobic zone 1, aerobic zone 2 and aerobic zone 3 are respectively connected to the air blowing system, and an aeration control valve and a rotor flowmeter are respectively arranged on the connected pipelines.

[0013] As a preferred solution of the present invention, the anaerobic zone, the anoxic zone 1, the anoxic zone 2 and the anoxic zone 3 are respectively provided with anaerobic ammonia oxidation fillers.

[0014] As a preferred solution of the present invention, the anaerobic zone is provided with an anaerobic zone agitator, the anoxic zone 1 is provided with an anoxic zone 1 agitator, the anoxic zone 2 is provided with an anoxic zone 2 agitator, and the anoxic zone 3 is provided with an anoxic zone 3 agitator.

[0015] As a preferred solution of the present invention, the effluent from the anoxic zone 3 enters the Fenton reactor after passing through a secondary sedimentation tank.

[0016] As a preferred embodiment of the present invention, a sludge return pump and a sludge return control valve are provided on the pipeline between the secondary sedimentation tank and the anaerobic zone, and the secondary sedimentation tank is also provided with a sludge discharge control valve for discharging sludge externally; a Fenton iron sludge return pump is provided on the pipeline between the Fenton reactor and the anaerobic zone and the anoxic zone.

[0017] As a preferred solution of the present invention, a nitrification liquid reflux pump and a nitrification liquid reflux control valve are provided on the reflux pipelines between the aerobic zone 2 and the anoxic zone 1.

[0018] The present invention also provides a method for coupling iron-ammonia oxidation and anaerobic ammonia oxidation of Fenton residual iron sludge using the above device, comprising the following steps:

[0019] 1) Inoculate the excess sludge from a common urban sewage treatment plant and add it to a five-stage reactor, and add the anaerobic ammonium oxidation filler inoculated with the anaerobic ammonium oxidation biofilm to the anaerobic zone, anoxic zone 1, anoxic zone 2 and anoxic zone 3 in the five-stage reactor;

[0020] 2) Industrial wastewater or industrial wastewater containing part of municipal sewage enters the anaerobic zone from the water inlet tank, and the sludge in the secondary sedimentation tank is also returned to the anaerobic zone through the sludge return pump; the nitrification liquid returns from the aerobic zone 2 to the anoxic zone 1 through the nitrification liquid return pump; the flow direction of the wastewater in the five-stage reactor is from the anaerobic zone to the anoxic zone 1, and flows through the aerobic zone 1, aerobic zone 2, anoxic zone 2, anoxic zone 3 and aerobic zone 3 in sequence, and the mud and water are separated in the secondary sedimentation tank, and the effluent enters the Fenton reactor through the Fenton reactor inlet pump, and is discharged after removing the refractory organic matter;

[0021] 3) The iron sludge produced by the Fenton reactor enters the anaerobic zone and the anoxic zone II of the five-stage reactor through the Fenton iron sludge reflux pump;

[0022] 4) Control the blower to adjust the aeration volume in the aerobic zone so that the dissolved oxygen concentration in the aerobic zone is about 0.5mg / L-2.5mg / L;

[0023] 5) Control the hydraulic retention time of the five-stage reactor and discharge the excess sludge through the sludge discharge control valve;

[0024] 6) Use non-biochemical Fenton reactor to remove difficult-to-degrade organic matter in industrial wastewater to ensure that the overall effluent is stable and meets the standards.

[0025] As a preferred embodiment of the present invention, in step 1), the sludge concentration in the reactor is maintained at 2000-3000 mg / L, and the filling ratio of the anaerobic ammonium oxidation filler is 15%-30%.

[0026] As a preferred embodiment of the present invention, in step 5), the hydraulic retention time of the five-stage reactor is controlled at 12-18 hours, and the excess sludge is discharged through the sludge discharge control valve so that the sludge age of the flocculent sludge in the system is 15-20 days.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) The present invention utilizes the coupling of iron ammonia oxidation and anaerobic ammonium oxidation processes to treat industrial sewage or industrial sewage containing a small amount of urban sewage, retains anaerobic ammonium oxidizing bacteria through fillers, and strengthens the iron ammonia oxidation of the system through the continuous reflux of Fenton iron mud. Under the synergistic effect of iron ammonia oxidizing bacteria and anaerobic ammonium oxidizing bacteria, the coupling of iron ammonia oxidation and short-range denitrification anaerobic ammonium oxidation can simultaneously remove ammonia nitrogen and nitrate, and remove easily degradable organic matter.

[0029] 2) The present invention can achieve the purpose of reducing aeration, saving the addition of external carbon sources such as sodium acetate and methanol, and reducing operating costs.

[0030] 3) Iron salt is a commonly used phosphorus removal agent. The iron ions generated by the dissolution of the refluxed iron sludge can precipitate the phosphate in the system, thereby enhancing the phosphorus removal of the system.

[0031] 4) The method of the present invention can achieve the reduction and harmless treatment of iron sludge produced by Fenton, reduce the output of hazardous waste in the process of industrial wastewater treatment, has strong operability, is suitable for the upgrading and transformation of existing industrial sewage treatment plants (containing a large amount of industrial sewage), and is suitable for new sewage treatment plants with low carbon-nitrogen ratio influent water quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the device of the present invention.

[0033] In the figure, 1-water inlet tank; 2-raw water inlet pump; 3-anaerobic zone; 4-anoxic zone 1; 5-aerobic zone 1; 6-aerobic zone 2; 7-anoxic zone 2; 8-anoxic zone 3; 9-aerobic zone 3; 10-five-stage reactor; 11-second sedimentation tank; 12-Fenton reactor inlet pump; 13-Fenton reactor; 14-outlet pipe; 15-anaerobic zone agitator; 16-anoxic zone 1 agitator; 17-anoxic zone 2 agitator; 18-anoxic zone 3 agitator; 19-blower; 20-aeration control valve; 21-rotor flowmeter; 22-aerator; 23-nitrification liquid reflux pump; 24-nitrification liquid reflux control valve; 25-sludge control valve; 26-sludge reflux pump; 27-sludge reflux control valve; 28-Fenton iron sludge reflux pump; 29-anaerobic ammonia oxidation filler. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] See also Figure 1 The present invention provides a method and device for coupling iron-ammonia oxidation and anaerobic ammonia oxidation by Fenton residual iron sludge, comprising a water inlet tank 1, a five-stage reactor 10, a secondary sedimentation tank 11 and a Fenton reactor 13.

[0037] A raw water inlet pump 2 is provided on the water inlet tank 1 .

[0038] The five-stage reactor 10 includes an anaerobic zone, and two-stage anoxic zones and aerobic zones arranged alternately, namely, anaerobic zone 3, anoxic zone 1 4, aerobic zone 1 5, aerobic zone 2 6, anoxic zone 2 7, anoxic zone 3 8, and aerobic zone 3 9.

[0039] The secondary sedimentation tank 11 is provided with a sludge discharge control valve 25 , a sludge return pump 26 and a sludge return control valve 27 .

[0040] The Fenton reactor 13 is provided with a Fenton reactor water inlet pump 12 , a Fenton iron sludge reflux pump 28 and a water outlet pipe 14 .

[0041] The dissolved oxygen in the aerobic zone 1 5 , the aerobic zone 2 6 and the aerobic zone 3 9 is controlled by a blower 19 , an aeration control valve 20 and a rotor flowmeter 21 , and the activated sludge in the five-stage reactor 10 is aerated by an aerator 22 .

[0042] The anaerobic zone 3, the anoxic zone 1 4, the anoxic zone 2 7 and the anoxic zone 3 8 are installed with anaerobic ammonium oxidation fillers 29 with biofilms, and the filling ratio is 15%-30%.

[0043] The anaerobic zone 3, the anoxic zone 1 4, the anoxic zone 2 7 and the anoxic zone 3 8 are respectively equipped with an anaerobic zone agitator 15, an anoxic zone 1 agitator 16, an anoxic zone 2 agitator 17 and anoxic zone 3 agitator 18.

[0044] A nitrification liquid reflux pump 23 and a nitrification liquid reflux control valve 24 are provided on the reflux pipeline between the aerobic second zone 6 and the anoxic first zone 4.

[0045] The industrial wastewater in the water inlet tank 1 or the industrial wastewater containing part of the municipal sewage all enters the anaerobic zone 3 through the raw water inlet pump 2. The different reaction zones of the five-stage reactor 10 are connected by short pipes. The effluent passes through the secondary sedimentation tank 11 and is lifted by the Fenton reactor inlet pump 12 to enter the Fenton reactor 13. The sludge discharge of the secondary sedimentation tank 11 is controlled by the sludge discharge control valve 25. The sludge return of the secondary sedimentation tank 11 is regulated by the sludge return pump 26 and the sludge return control valve 27, and the sludge returns to the anaerobic zone 3; the iron sludge generated in the Fenton reactor 3 is returned to the anaerobic zone 3 and the anoxic zone 2 7 of the five-stage reactor 10 through the Fenton iron sludge return pump 28 through the pipeline.

[0046] Example 2

[0047] This embodiment provides a method for coupling iron-ammonia oxidation and anaerobic ammonia oxidation with Fenton residual iron sludge using the device of embodiment 1, comprising the following steps:

[0048] 1) Inoculate the residual sludge of ordinary urban sewage treatment plants and add it to the five-stage reactor 10, so that the sludge concentration in the reactor is maintained at 2000-3000 mg / L, and then add the anaerobic ammonium oxidation filler 29 inoculated with anaerobic ammonium oxidation biofilm to the anaerobic zone 3, anoxic zone 1 4, anoxic zone 2 (7) and anoxic zone 3 8 in the five-stage reactor 10, and the filling ratio is 15%-30%.

[0049] 2) Industrial wastewater or industrial wastewater containing part of municipal sewage enters the anaerobic zone 3 from the water inlet tank 1 through the raw water inlet pump 2, and the sludge in the secondary sedimentation tank 11 is also returned to the anaerobic zone 3 through the sludge return pump 26, wherein polyphosphate-accumulating bacteria absorb small molecular organic matter in the influent to release phosphorus, and the nitrate nitrogen carried in the sludge return utilizes the organic matter and ammonia nitrogen in the influent to perform short-range denitrification anaerobic ammonia oxidation denitrification, and denitrification denitrification occurs at the same time. The sludge return ratio is controlled at 50%-100%; the nitrification liquid returns from the aerobic zone 2 6 to the anoxic zone 1 4 via the nitrification liquid return pump 23, and the nitrification liquid can be denitrified by short-range denitrification anaerobic ammonia oxidation and denitrification, and the nitrification liquid return ratio is controlled at 150%-300%; the wastewater flows from the anaerobic zone 3 into the anoxic zone 1 4 in the five-stage reactor 10, and then flows through the aerobic zone 1 5, the aerobic zone 2 6, the anoxic zone 2 7, the anoxic zone 3 8 and the aerobic zone 3 9 in sequence, and the mud and water separation is realized in the second sedimentation tank 11, and the effluent enters the Fenton reactor 13 through the Fenton reactor inlet pump 12, and the refractory organic matter is removed before being discharged.

[0050] 3) The iron sludge produced by the Fenton reactor 13 enters the anaerobic zone 3 and the anoxic zone 2 7 of the five-stage reactor 10 through the Fenton iron sludge return pump 28, providing iron salts (trivalent iron) for the biochemical reaction system. The reflux of iron salts continuously enriches the iron-ammonia oxidizing bacteria in the five-stage reactor 10. In the anaerobic zone 3 and the anoxic zone 1 4, the nitrite and nitrate nitrogen produced by the iron-ammonia oxidation reaction are used by anaerobic ammonia oxidizing bacteria and denitrifying bacteria for denitrification. In this process, trivalent iron is reduced to divalent iron; in the following aerobic zone 1 5 and aerobic zone 2 6, part of the divalent iron is oxidized to trivalent iron, and the iron salt supplemented by the reflux is used together in the anoxic zone 2 7 and the anoxic zone 3 8 for iron-ammonia oxidation reaction, and denitrification is coupled with anaerobic ammonia oxidation and denitrification reactions to reduce the iron sludge production while utilizing the flocculation effect of iron salts and phosphates in the water to achieve the simultaneous removal of nitrogen and phosphorus in the wastewater.

[0051] 4) Control the blower 19 to adjust the aeration volume in the aerobic zone so that the dissolved oxygen concentration in the aerobic zone is about 0.5 mg / L-2.5 mg / L.

[0052] 5) The hydraulic retention time (HRT) of the five-stage reactor 10 is controlled at 12-18 hours, and the excess sludge is discharged through the sludge discharge control valve 25, so that the sludge age (SRT) of the flocculent sludge in the system is 15-20 days, and the anaerobic ammonia-oxidizing bacteria on the filler maintain a long sludge age;

[0053] 6) A non-biochemical Fenton reactor 13 is used to remove the difficult-to-degrade organic matter in industrial wastewater, ensuring that the overall effluent is stable and meets the standards.

[0054] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and evolutions of the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A device for coupling iron-ammonia oxidation and anaerobic ammonium oxidation by Fenton residual iron sludge, characterized in that: The device comprises an inlet tank, a five-stage reactor, a secondary sedimentation tank and a Fenton reactor which are connected in sequence; wherein the five-stage reactor comprises an anaerobic zone, an anoxic zone 1, an aerobic zone 1, an aerobic zone 2, anoxic zone 2, anoxic zone 3 and aerobic zone 3; the iron sludge produced by the Fenton reactor flows back to the anaerobic zone and the anoxic zone 2 through a pipeline; the sludge in the secondary sedimentation tank flows back to the anaerobic zone; and the aerobic zone 2 and the anoxic zone 1 are refluxed.

2. The device for coupling iron-ammonia oxidation and anaerobic ammonium oxidation of Fenton residual iron sludge according to claim 1, characterized in that: The bottoms of the aerobic zone 1, aerobic zone 2 and aerobic zone 3 are all provided with aerators; an air blowing system is also included, and the aerobic zone 1, aerobic zone 2 and aerobic zone 3 are respectively connected to the air blowing system, and the connected pipelines are respectively provided with an aeration control valve and a rotor flowmeter.

3. The device for coupling iron-ammonia oxidation and anaerobic ammonium oxidation of Fenton residual iron sludge according to claim 1, characterized in that: The anaerobic zone, the first anoxic zone, the second anoxic zone and the third anoxic zone are respectively provided with anaerobic ammonia oxidation fillers.

4. The device for coupling iron-ammonia oxidation and anaerobic ammonium oxidation of Fenton residual iron sludge according to claim 1, characterized in that: The anaerobic zone is provided with an anaerobic zone agitator, the anoxic zone 1 is provided with an anoxic zone 1 agitator, the anoxic zone 2 is provided with an anoxic zone 2 agitator, and the anoxic zone 3 is provided with an anoxic zone 3 agitator.

5. The device for coupling iron-ammonia oxidation and anaerobic ammonium oxidation of Fenton residual iron sludge according to claim 1, characterized in that: The effluent from the anoxic zone 3 enters the Fenton reactor after passing through the secondary sedimentation tank.

6. The device for coupling iron-ammonia oxidation and anaerobic ammonium oxidation of Fenton residual iron sludge according to claim 1, characterized in that: A sludge return pump and a sludge return control valve are provided on the pipeline between the secondary sedimentation tank and the anaerobic zone. The secondary sedimentation tank is also provided with a sludge discharge control valve for discharging sludge externally. A Fenton iron sludge return pump is provided on the pipeline between the Fenton reactor and the anaerobic zone and the anoxic zone.

7. The device for coupling iron-ammonia oxidation and anaerobic ammonium oxidation of Fenton residual iron sludge according to claim 1, characterized in that: A nitrification liquid reflux pump and a nitrification liquid reflux control valve are arranged on the reflux pipelines between the aerobic zone 2 and the anoxic zone 1.

8. A method for coupling iron-ammonia oxidation and anaerobic ammonium oxidation by Fenton residual iron sludge, characterized in that: Using the device according to any one of claims 1 to 7, the method comprises the following steps: 1) Inoculate the excess sludge from a common urban sewage treatment plant and add it to a five-stage reactor, and add the anaerobic ammonium oxidation filler inoculated with the anaerobic ammonium oxidation biofilm to the anaerobic zone, anoxic zone 1, anoxic zone 2 and anoxic zone 3 in the five-stage reactor; 2) Industrial wastewater or industrial wastewater containing part of municipal sewage enters the anaerobic zone from the water inlet tank, and the sludge in the secondary sedimentation tank is also returned to the anaerobic zone through the sludge return pump; the nitrification liquid returns from the aerobic zone 2 to the anoxic zone 1 through the nitrification liquid return pump; the flow direction of the wastewater in the five-stage reactor is from the anaerobic zone to the anoxic zone 1, and flows through the aerobic zone 1, aerobic zone 2, anoxic zone 2, anoxic zone 3 and aerobic zone 3 in sequence, and the mud and water are separated in the secondary sedimentation tank, and the effluent enters the Fenton reactor through the Fenton reactor inlet pump, and is discharged after removing the refractory organic matter; 3) The iron sludge produced by the Fenton reactor enters the anaerobic zone and the anoxic zone II of the five-stage reactor through the Fenton iron sludge reflux pump; 4) Control the blower to adjust the aeration volume in the aerobic zone so that the dissolved oxygen concentration in the aerobic zone is about 0.5 mg / L to 2.5 mg / L; 5) Control the hydraulic retention time of the five-stage reactor and discharge the excess sludge through the sludge discharge control valve; 6) Use non-biochemical Fenton reactor to remove difficult-to-degrade organic matter in industrial wastewater to ensure that the overall effluent is stable and meets the standards.

9. The method for coupling iron-ammonia oxidation and anaerobic ammonium oxidation by Fenton residual iron sludge according to claim 8, characterized in that: In step 1), the sludge concentration in the reactor is maintained at 2000-3000 mg / L, and the filling ratio of the anaerobic ammonium oxidation filler is 15%-30%.

10. The method for coupling iron-ammonia oxidation and anaerobic ammonium oxidation by Fenton residual iron sludge according to claim 8, characterized in that: In step 5), the hydraulic retention time of the five-stage reactor is controlled at 12 to 18 hours, and the excess sludge is discharged through the sludge discharge control valve so that the sludge age of the flocculent sludge in the system is 15 to 20 days.

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