A sewage biological denitrification and dephosphorization process based on magnetic carbon biofilm carrier

Abstract

The application discloses a wastewater biological enhanced denitrification and dephosphorization process based on a magnetic carbon biofilm carrier, which comprises the following steps: firstly, adding the powdered magnetic carbon biofilm carrier into activated sludge to perform aeration stirring and mixing, and then performing pre-membrane hanging to form magnetic sludge flocs; and then continuously adding the magnetic sludge flocs into an aerobic tank to perform sludge-membrane mixing operation; and the preparation method of the powdered magnetic carbon biofilm carrier comprises the following steps: (1) drying and crushing one or more than two of straw, wood powder and municipal sludge to obtain biomass powder; (2) mixing and impregnating the biomass powder with a salt solution containing iron elements, and then uniformly mixing ferromagnetic powder to obtain a mixture; (3) drying and crushing the mixture, and then placing the mixture into a sealed container to perform anoxic pyrolysis carbonization; and after the carbonization product is cooled, the carbonization product is ground by a ball mill to obtain the powdered magnetic carbon biofilm carrier.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, and in particular to a sewage biological denitrification and phosphorus removal process based on a magnetic carbon biofilm carrier. BACKGROUND

[0002] The processes used by sewage treatment plants mainly include A 2 / O, oxidation ditch and SBR process, etc. More than 65% of the urban sewage treatment plants have the problem of insufficient carbon source in the influent. Nearly 43% of the urban sewage treatment plants have a C / N ratio of less than 3 in the influent, which cannot meet the needs of microbial denitrification and phosphorus removal. This situation is particularly serious in some industrial and domestic mixed sewage treatment plants, and often requires extensive operation modes such as high aeration and high additional carbon source to achieve stable and standard discharge of carbon, nitrogen and phosphorus elements in the effluent of the sewage treatment plant, which has the problems of large coagulant dosage and high operation cost. The current sewage treatment plants are faced with the dual tasks of pollution reduction and carbon reduction, and need to promote sewage resource utilization, optimize process flow, improve treatment efficiency, and improve sludge disposal and comprehensive utilization level.

[0003] The mainstream A / O biological denitrification and phosphorus removal process is difficult to achieve simultaneous and efficient denitrification and phosphorus removal. Increasing the activated sludge concentration and the diversity of biological flora on the basis of the existing structures of the sewage treatment plant to strengthen the biochemical efficiency and realize the upgrading and efficiency improvement of the sewage treatment plant is the mainstream trend. The commonly used MBBR technology has the problems of small specific surface area of the filler, poor local accumulation and mixing state of the filler, and high energy consumption of stirring and oxygenation. The high-concentration powder carrier biological fluidized bed is a process in which powder carriers (diatomite, bentonite, attapulgite, etc.) are put into the biochemical tank to induce the formation of a core of the powder carrier and the growth of microorganisms with large adhesion force attached to the core to improve the diversity of the biological flora, so that the "double sludge age" can be realized on the basis of the "double sludge method", and the denitrification and phosphorus removal effect can be simultaneously improved. At the same time, after the separation of the sludge and water in the secondary sedimentation tank, the powder carriers in the sludge need to be separated and recovered. The powder carriers are mainly recovered by a hydrocyclone based on the density difference between the powder carrier particles and the biological flocs. Since the hydrocyclone has low recovery efficiency for the low-density and small-particle-size powder carriers, and it is difficult to separate the powder carriers from the biological flocs by using centrifugal force, the powder carrier needs to be added in a large amount in the engineering operation, and the operation cost is high. In recent years, due to the good magnetic responsiveness of the magnetic powder carrier, the magnetic carrier biological fluidized bed process has good application potential in the upgrading and efficiency improvement and pollution reduction and carbon reduction of the existing sewage treatment plants. The magnetic powder carrier can be efficiently separated and recovered by using a magnetic separation device.

[0004] The sludge produced in sewage treatment plants has a large amount of organic matter, and straw or wood chips and other agricultural waste are also urgently needed for resource utilization. Under the condition of anoxic high temperature, carbonization can form biochar with high graphitization degree. Biochar has the advantages of large specific surface area, small pore size, and rich functional groups. It has porosity and electrical conductivity. As a biofilm carrier, biochar has the advantages of good biocompatibility and fast biofilm formation. Further functional modification of biochar to prepare magnetic carbon biofilm carriers can use magnetic force cyclone separation or magnetic disk separation to achieve efficient recovery. Coupling with the existing AO process of the sewage treatment plant can construct a sludge-membrane mixed process based on the magnetic carbon biofilm carrier, and also can realize the high-value recycling of sludge, and provides a new path for the low-carbon operation of the future sewage treatment plant.

[0005] The preparation methods of magnetic biochar mainly include chemical precipitation method, hydrothermal method, microwave heating method and one-step pyrolysis method, etc. A large amount of chemical reagents (such as sodium borohydride, sodium nitrate, ammonium hydroxide) and magnetic iron precursors (such as FeCl3 and FeCl2) are usually used to react to load magnetic substances in biochar. These methods often involve the composite process of biochar as a precursor with metal or metal oxide, which has the disadvantages of complex preparation method, high temperature and high pressure environment required for preparation, and use of toxic reducing agents. Another common method for preparing magnetic biochar is to immerse the biochar raw material in an iron-containing precursor solution, and then treat it through stirring, solid-liquid separation and drying, etc. After one-step carbonization, magnetic biochar is prepared. Patent application CN111408349A discloses a preparation method of straw-based magnetic porous biochar, which includes straw pretreatment, straw powder soaking, high-temperature carbonization treatment and hydrothermal process for preparing straw-based magnetic porous biochar. Patent application CN105536700A discloses a method for preparing biochar adsorption and catalytic material from straw. The preparation steps include cleaning pretreatment of straw raw material, then immersing in ferric salt solution, vacuum filtration, drying the filter cake, and then carbonizing under inert gas condition to obtain biochar adsorption and catalytic material finished product. SUMMARY

[0006] The present application provides a sewage biological enhanced denitrification and phosphorus removal process based on magnetic carbon biofilm carrier, which can solve the problems of low denitrification and phosphorus removal efficiency, large amount of carbon source, low denitrification efficiency, sludge age contradiction between nitrifying bacteria and phosphorus removal bacteria, sludge expansion, large occupation area and other problems in the conventional AO process or A 2 / O process of low-carbon municipal sewage treatment plant.

[0007] A sewage biological enhanced denitrification and phosphorus removal process based on magnetic carbon biofilm carrier, comprising: firstly adding powdered magnetic carbon biofilm carrier into activated sludge for aeration stirring and mixing to form magnetic sludge flocs, and then continuously feeding the magnetic sludge flocs into the aerobic tank for sludge-membrane mixed process operation.

[0008] The preparation method of the powdered magnetic carbon biofilm carrier comprises the following steps:

[0009] (1) drying and crushing one or more than two of straw, wood powder and municipal sludge to obtain biomass powder;

[0010] (2) mixing and impregnating the biomass powder with a salt solution containing iron elements, and then adding ferromagnetic powder to uniformly mix to obtain a mixture; the mass ratio of the biomass powder, the salt containing iron elements and the ferromagnetic powder is 100:150-200:2-10, and the mixture obtained under this ratio contains main elements such as Fe, C, S and O; under this ratio, both zero-valent iron and iron ions are contained, and the molar ratio of carbon elements and iron elements is close to 1:1; the C and Fe elements generated by pyrolysis and carbonization of such a mixture can be subjected to oxidation and reduction and electron transfer by aeration mixing in sewage, which is beneficial to accelerating interspecific electron transfer among microorganisms;

[0011] (3) drying and crushing the mixture, and then placing it in a sealed container to perform anaerobic pyrolysis and carbonization; after cooling the carbonization product, it is ground by a ball mill to obtain a powdered magnetic carbon biofilm carrier; the heating program of the anaerobic pyrolysis is to heat at a rate of 8-15℃ / min to 290-310℃ (preferably 300℃) for 30-35min, and then heat at a rate of 5-10℃ / min to 850-1000℃ for 60-65min; the mixture is heated at 290-310℃ (preferably 300℃) to remove the bound water in the mixture, and the lignin, cellulose and organic matter in the sludge are rapidly thermally decomposed to remove hydrogen and oxygen, the free carbon atoms rearrange to form intramolecular cyclization and intermolecular aromatization reactions, and condense into carbon microcrystalline structures; further, the hydrogen and carbon monoxide generated by the carbonization product under the anaerobic state at 850-1000℃ will reduce the zero-valent iron, iron sulfide and magnetite generated by the iron ions to be inlaid in the pores of the porous carbon, which is beneficial to the prepared magnetic carbon biofilm carrier to have a larger specific surface area, stronger magnetic response and electron supply capacity.

[0012] The present application is an integral and indivisible technical solution, which creatively uses the method of mixed biomass thermochemical reduction through a specific anaerobic pyrolysis heating program to reduce iron salt to magnetite, γ-Fe2O3, etc., so that the prepared biofilm carrier has good magnetic response and can be used for activated sludge aeration and membrane formation to form magnetic sludge flocs and further applied to an aerobic tank for mud membrane mixing method operation.

[0013] The preparation method of the present application has interlocking and synergistic steps and condition parameters, simple process route, low raw material cost, easy production process control, and the prepared magnetic carbon biofilm carrier has good magnetic response (saturated magnetic induction intensity greater than 20 emu / g), has a porous carbon structure and a large specific surface area (greater than 95 m 2 / g), and has the advantages of fast biofilm hanging speed and good biocompatibility as a biofilm carrier. In addition, the magnetic carbon biofilm carrier itself has strong magnetic response in a magnetic field, and can be efficiently separated and recovered by using a magnetic separation device when the residual sludge is discharged from the secondary sedimentation tank after using the biofilm carrier for biological enhanced nitrogen and phosphorus removal in wastewater, and can be used in the fields of in-situ upgrading and reconstruction of biochemical processes in wastewater treatment plants and cost reduction and efficiency improvement.

[0014] In step (1), the straw can include at least one of corn straw, rice straw, and wheat straw.

[0015] In step (1), the wood powder can include waste powder after wood processing.

[0016] In step (1), the municipal sludge can include biochemical sludge after dewatering in a wastewater treatment plant mainly using domestic wastewater, and the organic matter content is preferably greater than 50wt%.

[0017] In step (1), the particle size of the biomass powder can be 200-300 mesh.

[0018] In some preferred examples, in step (1), at least one of the straw and the wood powder is mixed with the municipal sludge at a mass ratio of 1-6:2, and then dried and crushed to obtain the biomass powder, wherein the straw and the wood powder mainly provide reducing hydrogen and carbon monoxide in the pyrolysis carbonization process, and the sludge can increase the viscosity of the mixture, facilitating uniform mixing, and the metal ions such as iron in the sludge can be reduced to low or zero valence state in the pyrolysis process, which is beneficial to uniformly loading the prepared magnetic carbon biofilm carrier with active components such as zero-valent iron, iron sulfide, and magnetite at the micro level.

[0019] In step (2), the salt containing iron elements can include at least one of ferrous sulfate heptahydrate, ferrous chloride, iron sulfate, and ferric chloride.

[0020] In step (2), the ferromagnetic powder can include at least one of reduced iron powder and cast iron powder.

[0021] In step (2), the particle size of the ferromagnetic powder can be less than 200 mesh.

[0022] In step (3), the drying temperature can be 105-110℃.

[0023] In step (3), the ball milling can be performed by using a horizontal ball mill for 30-60 min, and the powder magnetic carbon biofilm carrier can be obtained by passing through a 200 mesh screen.

[0024] In a preferred embodiment, the particle size of the powder magnetic carbon biofilm carrier in the wastewater biological denitrification and phosphorus removal process is less than 200 mesh.

[0025] In the wastewater biological denitrification and phosphorus removal process, the activated sludge can be the return sludge at the bottom of the secondary sedimentation tank.

[0026] In some preferred embodiments, in the wastewater biological denitrification and phosphorus removal process, the sludge concentration during aeration and stirring is 8-15 g / L, the dosing concentration of the powder magnetic carbon biofilm carrier is 4-8 g / L, the stirring speed is 30-60 r / min, the dissolved oxygen during aeration and stirring is controlled to be more than 4 mg / L, and the hydraulic retention time is 1-2 days, so that the microbial adhesion and growth on the surface of the magnetic carbon biofilm carrier and the pre-membrane formation can be achieved.

[0027] In a preferred embodiment, in the wastewater biological denitrification and phosphorus removal process, the residual sludge in the secondary sedimentation tank is recycled by a magnetic separation device to recover the magnetic carbon biofilm carrier, and the recovered magnetic carbon biofilm carrier is returned to the aerobic tank for recycling, so that the sludge-membrane mixing method is realized by the recycling of the magnetic carbon biofilm carrier, the sludge age contradiction between denitrifying bacteria and phosphorus-removing bacteria is solved, and the in-situ upgrading and efficiency improvement can be realized without changing the AO system structure of the wastewater treatment plant.

[0028] Further, the magnetic separation device can be one or a combination of a magnetic cyclone separator and a magnetic disk separator.

[0029] The preparation method route is simple, the raw material cost is low, the prepared magnetic carbon biofilm carrier has good magnetic response, has a porous carbon structure and a large specific surface area, has the advantages of fast membrane formation speed and good biocompatibility as a biofilm carrier. After the powder magnetic carbon biofilm carrier is continuously added to the existing aerobic tank of the wastewater treatment plant after aeration and stirring mixing and pre-membrane formation, the sludge-membrane mixing method can be realized, the effect of strengthening denitrification and phosphorus removal is achieved, and the in-situ upgrading and efficiency improvement of the biochemical process of the wastewater treatment plant are suitable.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] 1) The sludge and biomass in the wastewater treatment plant have a huge storage, which is a key field for the resource utilization of large-scale solid waste at the present time, and the recycling of the magnetic carbon biofilm carrier for the upgrading and efficiency improvement of the wastewater treatment plant conforms to the concept of low-carbon modification, which is conducive to promoting the high-value reuse of sludge and biomass.

[0032] 2) The magnetic carbon biofilm carrier prepared by the present application mainly contains elements of Fe, O, C and S, and contains zero-valent iron and iron sulfide, which can be used as components of cell substances such as nitrogenase and iron redox protein in the microbial metabolic process, and can be used as an electron donor to participate in the metabolic process of microorganisms. The zero-valent iron in the magnetic carbon can also act as a coenzyme activator, improve the oxidation capacity of the sludge, and strengthen the catalytic activity of the enzyme. In addition, Fe 2+ 3+ in the magnetic carbon biofilm carrier can reduce the surface negative charge of the cells, enhance the van der Waals force between the cells, and promote the self-aggregation of the sludge.

[0033] 3) Compared with diatomite, bentonite and attapulgite carriers, the magnetic carbon biofilm carrier can coagulate and adsorb phosphorus, enrich nitrifying bacteria to improve the denitrification efficiency, improve the biological denitrification and phosphorus removal efficiency, optimize the structure of activated sludge flocs, and improve the ability of microorganisms to resist changes in external environmental factors.

[0034] 4) The ferromagnetic particles in the magnetic carbon biofilm carrier are uniformly loaded on the surface or pores of the carbon, and have high magnetic saturation strength. The magnetic response in an external magnetic field can be used to separate or recycle the magnetic carbon biofilm carrier through a magnetic separation device. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Figure 1 is a preparation flowchart of the magnetic carbon biofilm carrier of the present application.

[0036] Figure 2 , Figure 3 Figure 2 is a scanning electron microscope (SEM) photo of the magnetic carbon biofilm carrier of Example 1.

[0037] Figure 4 Figure 3 is a hysteresis loop diagram of the magnetic carbon biofilm carrier of Example 1.

[0038] Figure 5 Figure 4 is an X-ray diffraction (XRD) diagram of the magnetic carbon biofilm carrier of Example 1, in which the horizontal coordinate unit is degree (°) and the vertical coordinate unit is arbitrary unit (a.u.). DETAILED DESCRIPTION

[0039] The present application will be further described below in conjunction with the drawings and specific examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application. The operation methods not specified in the following examples are usually carried out according to the conventional conditions or the conditions recommended by the manufacturers.

[0040] A preparation flowchart of the magnetic carbon biofilm carrier of the present application is shown in Figure 1. Figure 1 ​The preparation process is shown, including impregnation of mixed biomass powder and iron salt solution, stirring mixing of ferromagnetic powder, drying, high-temperature anoxic pyrolysis carbonization, ball milling and screening preservation and the like. First, the biomass such as sewage treatment plant sludge, straw, wood powder and the like is crushed and uniformly mixed according to a certain proportion; the mixed biomass powder is impregnated with the iron salt solution and then ferromagnetic powder is added to obtain a mixture; the mixture is dried and crushed and then placed in a closed container (which can be steel) for anoxic pyrolysis carbonization; and the carbonization product is cooled, ball milled and screened to obtain a powdered magnetic carbon biofilm carrier.

[0041] Example 1

[0042] The biochemical sludge of a municipal sewage treatment plant and wood powder are dried, impregnated with ferrous sulfate heptahydrate solution and then mixed uniformly with reduced iron powder, wherein the mass ratio of dry sludge, wood powder, ferrous sulfate heptahydrate and reduced iron powder is 10:30:80:2. The obtained mixture is dried in an oven at a temperature of 110°C, crushed and then placed in a closed stainless steel tank body and sealed, and then placed in a pyrolysis furnace, heated at a rate of 10°C / min to 300°C for 30 min, and then heated at a rate of 5°C / min to 850°C for 60 min. After cooling, the mixture is ground in a horizontal ball mill for 30 min, screened through a 200 mesh standard sieve to obtain a powdered magnetic carbon biofilm carrier.

[0043] To further characterize and analyze the surface morphology and element composition of the magnetic carbon biofilm carrier, the sample is characterized and analyzed by SEM, magnetic hysteresis loop determination and XRD. The SEM surface morphology analysis results show that the surface of the magnetic carbon biofilm carrier presents a honeycomb-like porous structure, and a large number of pores can be seen inside, with different pore sizes and a large specific surface area. Figure 2 Figure 3 The magnetic hysteresis loop determination shows that the saturation magnetic induction intensity is 25 emu / g, and the magnetic carbon biofilm carrier has good magnetic response and can be separated and recovered under the action of magnetic field force. Figure 4 Figure 5 The XRD results show that in addition to porous carbon, a high proportion of iron oxide, iron sulfide and iron carbide and a small amount of zero-valent iron are newly generated.

[0044] The magnetic carbon biofilm carrier prepared above is subjected to laboratory biochemical biofilm test evaluation. The activated sludge of a sewage treatment plant is added to a 0.5L stirring and aeration barrel, the sludge concentration is 14.2g / L, 7g / L of the magnetic carbon biofilm carrier is added for pre-activation and biofilm culture, after stirring and mixing reaction for 2 days, 1L of the aerobic reactor is added in batches so that the concentration of the magnetic carbon biofilm carrier reaches 3g / L, and the sludge concentration in the aerobic reactor gradually increases from 3.5g / L to about 6.5g / L in 10 days, and the SV 30 ​​The settling property of the sludge in the aerobic reactor was obviously improved after 20 days of acclimation, and the SV 30 The COD, ammonia nitrogen and total phosphorus of the raw wastewater and the treated wastewater were decreased to 9%, 0. 5% and 0. 02%, respectively. The changes of the wastewater quality before and after the treatment are shown in Table 1.

[0045] Table 1 Changes of the wastewater quality before and after the treatment

[0046]

[0047] Example 2

[0048] The biochemical sludge of a municipal wastewater treatment plant, straw powder and ferrous sulfate heptahydrate solution were mixed uniformly, and the mass ratio of the dry sludge, straw powder and ferrous sulfate heptahydrate was 20:30:80. The mixture was dried in an oven at 110°C, crushed, and then put into a sealed stainless steel tank and sealed, and then put into a pyrolysis furnace. The temperature was raised to 300°C at a rate of 10°C / min, and then raised to 1000°C at a rate of 5°C / min for 60 min. After cooling, the mixture was ground in a horizontal ball mill for 50 min, and then sieved through a 200-mesh standard sieve to obtain a powdered magnetic carbon biofilm carrier.

[0049] The magnetic carbon biofilm carrier sample was characterized and analyzed by SEM-EDS, hysteresis loop measurement and XRD. The SEM-EDS measurement showed that the surface of the magnetic carbon biofilm carrier was mainly composed of C, O, Fe and S elements, and the weight percentages were 5.12%, 29.21%, 65.45% and 0.22%, respectively. The hysteresis loop measurement showed that the saturation magnetic induction was 22emu / g, and the magnetic response was good. The XRD characterization analysis showed that in addition to porous carbon, a high proportion of iron sulfide, iron carbide and zero-valent iron were newly generated.

[0050] Example 3

[0051] The biochemical sludge of a municipal wastewater treatment plant, wood powder and ferric chloride solution were mixed uniformly, and the mass ratio of the dry sludge, wood powder and ferric chloride was 40:20:90. The mixture was dried in an oven at 110°C, crushed, and then put into a sealed stainless steel tank and sealed, and then put into a pyrolysis furnace. The temperature was raised to 300°C at a rate of 10°C / min, and then raised to 900°C at a rate of 5°C / min for 60 min. After cooling, the mixture was ground in a horizontal ball mill for 40 min, and then sieved through a 200-mesh standard sieve to obtain a powdered magnetic carbon biofilm carrier.

[0052] The magnetic carbon bio-membrane carrier sample was characterized by SEM, automatic physical adsorption instrument and XRD. The SEM determination showed that there were more gaps on the surface of the magnetic carbon bio-membrane carrier. The BET specific surface area was 96 m 2 / g, the XRD characterization analysis showed that in addition to the porous carbon, the newly generated ferroferric oxide, iron oxide, and the characteristic peaks of iron sulfide and zero-valent iron also appeared.

[0053] In addition, it should be understood that, after reading the above description of the present application, those skilled in the art can make various modifications or modifications to the present application, and these equivalent forms also fall within the scope defined by the claims attached to the present application.

Claims

1. A wastewater biological denitrification and dephosphorization process based on magnetic carbon biofilm carrier, characterized in that, The application relates to a powder magnetic carbon biofilm carrier and a preparation method thereof. The powder magnetic carbon biofilm carrier is first added into activated sludge for aeration stirring mixing to form magnetic sludge flocs, and then the magnetic sludge flocs are continuously added into an aerobic tank for sludge film mixing operation; the activated sludge is backflow sludge at the bottom of a secondary sedimentation tank, the sludge concentration during aeration stirring is 8-15 g / L, the adding concentration of the powder magnetic carbon biofilm carrier is 4-8 g / L, the stirring speed is 30-60 r / min, the dissolved oxygen during aeration stirring is controlled to be higher than 4 mg / L, and the hydraulic retention time is 1-2 days; The preparation method of the powder magnetic carbon biofilm carrier comprises the following steps: (1) at least one of straw and wood powder is mixed with municipal sludge at a mass ratio of 1-6:2, and then the mixture is dried and crushed to obtain biomass powder; (2) the biomass powder is mixed with a salt solution containing iron elements, and then ferromagnetic powder is added and uniformly mixed to obtain a mixture; the mass ratio of the biomass powder, the salt containing iron elements and the ferromagnetic powder is 100:150-200:2-10; (3) the mixture is dried and crushed, and then is placed in a sealed container to perform anoxic pyrolysis carbonization; after the carbonization product is cooled, the powder magnetic carbon biofilm carrier is obtained through ball milling; the heating program of the anoxic pyrolysis is that the temperature is raised to 290-310 DEG C at a rate of 8-15 DEG C / min and is kept for 30-35 min, and then the temperature is raised to 850-1000 DEG C at a rate of 5-10 DEG C / min and is kept for 60-65 min.

2. The wastewater biological nitrogen and phosphorus removal process according to claim 1, characterized in that, In step (1), the straw comprises at least one of corn straw, rice straw and wheat straw; The wood powder comprises waste powder after wood processing; The municipal sludge comprises biochemical sludge after dewatering of a sewage treatment plant mainly using domestic sewage, and the organic matter content is greater than 50 wt%; The particle size of the biomass powder ranges from 200 to 300 meshes. In step (2), the salt containing iron elements comprises at least one of ferrous sulfate heptahydrate, ferrous chloride, iron sulfate and iron chloride; 3. The wastewater biological nitrogen and phosphorus removal process according to claim 1, characterized in that, The ferromagnetic powder comprises at least one of reduced iron powder and cast iron powder; the particle size of the ferromagnetic powder is less than 200 meshes. In step (3), the drying temperature is 105-110 DEG C. In step (3), the ball milling is performed for 30-60 min by using a horizontal ball mill, and the powder magnetic carbon biofilm carrier is obtained after being screened through a 200-mesh screen.

4. The wastewater biological nitrogen and phosphorus removal process according to claim 1, characterized in that, The particle size of the powder magnetic carbon biofilm carrier is less than 200 meshes.

5. The wastewater bioaugmentation process for nitrogen and phosphorus removal according to claim 1, characterized in that, The residual sludge in the secondary sedimentation tank is recycled by a magnetic separation device to recover the magnetic carbon biofilm carrier, and the recovered magnetic carbon biofilm carrier is returned to the aerobic tank for recycling.

6. The wastewater bioaugmentation process for nitrogen and phosphorus removal according to claim 1, characterized in that, The magnetic separation device is one or a combination of a magnetic cyclone separator and a magnetic disk separator.

7. The wastewater bioaugmentation process for nitrogen and phosphorus removal according to claim 1, characterized in that, ​ 8. The wastewater biological nitrogen and phosphorus removal process according to claim 7, characterized in that, ​

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