A multi-stage cyclone-magnetic stabilization heterogeneous fenton oxidation sewage treatment device and a sewage treatment method

Abstract

The application provides a multi-stage rotating flow-magnetic stabilization heterogeneous Fenton oxidation sewage treatment device and a sewage treatment method, and relates to the technical field of sewage treatment. The device comprises a premixing rotating flow zone, a main reaction zone and a water outlet separation zone which are sequentially connected in sequence from bottom to top. A rotating cutting type micro-nano bubble aeration device is arranged at the bottom of the premixing rotating flow zone to generate micro-nano bubbles and form initial rotating flow. Rotating flow devices and magnetic stabilization grids are alternately arranged in the main reaction zone. An external magnetic field generator is arranged on the outer wall of the reaction device at the position corresponding to the magnetic stabilization grid. A slanting plate sedimentation unit and a water outlet weir are arranged in the water outlet separation zone to realize in-situ separation of the catalyst. The application can strengthen gas-liquid-solid three-phase mass transfer, improve the utilization rate of hydrogen peroxide, reduce catalyst loss and sludge production, and is suitable for advanced treatment of difficult-to-degrade organic sewage such as landfill leachate.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a multi-stage cyclone-magnetically stabilized heterogeneous Fenton oxidation wastewater treatment device and method. Background Technology

[0002] With rapid industrialization, the concentration of various recalcitrant organic pollutants in industrial wastewater is increasing daily, and traditional biological treatment methods have limited effectiveness in removing these pollutants. Advanced oxidation processes (AOPs), as a highly efficient method for treating recalcitrant organic pollutants, have received widespread attention in recent years. Among them, the Fenton process, due to its fast reaction speed and high treatment efficiency, has become one of the most promising advanced oxidation technologies.

[0003] However, traditional homogeneous Fenton oxidation technology has significant limitations: the reaction requires strongly acidic conditions (pH≈3), consuming large amounts of acid-base adjusters; the iron-ion catalyst is lost with the wastewater after the reaction, forming a large amount of iron-containing sludge, causing secondary pollution; and the utilization rate of hydrogen peroxide is low, resulting in high operating costs. To solve these problems, heterogeneous Fenton oxidation technology has emerged, which expands the applicable pH range and reduces the generation of iron sludge by immobilizing the iron-based catalyst.

[0004] Fenton reactors, as an important carrier of heterogeneous Fenton oxidation technology, further improve reaction efficiency by providing favorable mass transfer conditions and catalyst interfacial contact. However, commercially available heterogeneous Fenton oxidation reactors still face many technical bottlenecks: catalyst loss and deactivation are inevitable during long-term operation, requiring frequent replenishment of fresh catalyst; gas-liquid-solid three-phase mass transfer efficiency is low, with flow dead zones and short-circuiting phenomena; energy consumption is high, especially with a large proportion of energy consumption in the aeration system; and catalyst separation and recovery are difficult, leading to increased operating costs.

[0005] Existing improvement schemes mostly focus on catalyst modification, but research on reactor structure innovation and process intensification is relatively insufficient. In particular, systematic solutions are lacking in areas such as achieving efficient mass transfer, reducing catalyst loss, and lowering energy consumption. Therefore, developing a novel, efficient, economical, and energy-saving heterogeneous Fenton oxidation reactor is of great significance for promoting the widespread application of advanced oxidation technologies in wastewater treatment and represents a key technical challenge that urgently needs to be addressed in the current water treatment technology field. Summary of the Invention

[0006] In view of this, the embodiments of this application provide a multi-stage cyclone-magnetically stabilized heterogeneous Fenton oxidation wastewater treatment device and wastewater treatment method with high mass transfer efficiency, low catalyst loss, and stable operation, so as to improve the gas-liquid-solid three-phase mass transfer efficiency, reduce catalyst loss, and improve the treatment efficiency and operational stability of recalcitrant organic wastewater.

[0007] The embodiments of this application provide the following technical solution: a multi-stage cyclone-magnetically stabilized heterogeneous Fenton oxidation wastewater treatment device, including a reaction device body with a vertical tower structure, wherein the reaction device body includes, from bottom to top, an interconnected premixed cyclone zone, a main reaction zone and an effluent separation zone;

[0008] The bottom of the premixed swirling zone is equipped with a rotary shearing micro-nano bubble aeration device for generating micro-nano bubbles and forming an initial swirling flow. The main reaction zone is alternately equipped with cyclones and magnetically stabilized grids, and the outer wall of the main body of the reaction device is provided with an external magnetic field generator for generating an alternating magnetic field at the position corresponding to the magnetically stabilized grid. The effluent separation zone is equipped with an inclined plate sedimentation unit and an effluent weir for in-situ separation of the catalyst.

[0009] According to one embodiment of this application, the rotary shearing micro / nano bubble aeration device includes a premixed swirl cone, a pressure-relieving microporous disk, a fixed swirl disk, and a high-speed rotating microbubble shear disk arranged sequentially from bottom to top; wherein, the pressure-relieving microporous disk and the fixed swirl disk are located inside the cone of the premixed swirl cone, and the microbubble shear disk is located above the cone opening of the premixed swirl cone.

[0010] According to one embodiment of this application, the pressure-relieving microporous disk is connected to a water inlet located at the bottom of the main body of the reaction device, and a dissolved air tank and a water pump are connected to the outside of the water inlet.

[0011] According to one embodiment of this application, the main reaction zone is provided with at least three layers of the cyclone separators and at least two layers of the magnetically stabilized grids. The cyclone separators are provided with guide vanes at a set angle to the horizontal plane to cut bubbles, enhance turbulence, and maintain the fluidization state of the catalyst particles.

[0012] According to one embodiment of this application, the magnetically stabilized grid is a cylindrical structure, which is alternately stacked with the cyclone separator; the magnetically stabilized grid forms a rhomboid channel or a wave-shaped three-dimensional channel inside.

[0013] According to one embodiment of this application, the external magnetic field generator is a Helmholtz coil, which is installed on the outer wall of the main body of the reaction device, facing the magnetically stabilized grid. The Helmholtz coil operates in an intermittent mode to generate a pulsed magnetic field with adjustable intensity.

[0014] This application also provides a method for wastewater treatment using the above-described apparatus, comprising the following steps: Step 1. Pre-treat the wastewater and adjust its pH to an acidic range; Step 2. The wastewater is introduced into the premixed cyclone zone, and an oxidant and a magnetic heterogeneous Fenton catalyst are added into the device; Step 3. Turn on the rotary micro-nano bubble aeration device and the external magnetic field generator to allow the catalyst to fully contact and mix with the wastewater under the action of fluidization and magnetic stabilization; Step 4. The mixture is introduced into the main reaction zone, where a heterogeneous Fenton oxidation reaction is carried out under the synergistic effect of the hydrocyclone, magnetically stabilized grid and external magnetic field generator. Step 5. The reaction mixture enters the effluent separation zone, where the catalyst is separated by the inclined plate sedimentation unit. The separated catalyst is returned to the main reaction zone, and the separated clear water is discharged through the effluent weir.

[0015] According to one embodiment of this application, the oxidant is added in a multi-point addition manner, with oxidant addition points set at the inlet of the premixed swirl zone and the rear section of the main reaction zone, and the ratio of the amount of oxidant added to the premixed swirl zone to the amount added to the main reaction zone is 70:30.

[0016] According to one embodiment of this application, in step 4, the distribution and residence time of the catalyst in the main reaction zone are controlled by adjusting the magnetic field strength of the external magnetic field generator.

[0017] According to one embodiment of this application, in step 4, the volume concentration of the catalyst in the main reaction zone is maintained at 12%-15% by an intelligent control system, the pH during the reaction process is 3.8-4.2, and the ORP value of the reaction system is 280-320mV.

[0018] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least: (1) The catalyst loss rate of the present invention is extremely low: the mass transfer process is effectively enhanced by the combination of "magnetic stabilization + cyclone separation" technology, and the efficient in-situ separation and reuse of catalyst are realized, which significantly reduces the catalyst loss rate and operating cost, and provides an efficient and economical new solution for the treatment of recalcitrant organic wastewater.

[0019] (2) High mass transfer efficiency: The design of “micro-nano bubbles + multi-stage swirl plate” greatly enhances the three-phase mass transfer process and improves the reaction rate and processing efficiency.

[0020] (3) Low energy and drug consumption: Micro-nano bubbles improve oxygen / ozone utilization, and the intelligent control system enables precise addition of oxidants and acids and bases, avoiding waste.

[0021] (4) Strong adaptability and high resistance to shock loads: The multi-level zoning design and intelligent control broaden the reactor’s adaptability to water quality and quantity, provide a wider pH application window, and also enhance the device’s resistance to shock loads.

[0022] (5) Low sludge production: The heterogeneous reaction mode and catalyst recovery system reduce the amount of iron sludge generated from the source, thus reducing the burden of solid waste disposal. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a first schematic diagram of the overall structure of the device of the present invention; Figure 2 This is a second schematic diagram of the overall structure of the device of the present invention; Figures 3(a)-3(c) are schematic diagrams of key components of the premixed swirl zone of the present invention; wherein, Figure 3(a) is a schematic diagram of the pressure relief microporous disk; Figure 3(b) is a schematic diagram of the swirl disk; and Figure 3(c) is a schematic diagram of the microbubble shear disk. Figures 4(a) and 4(b) are schematic diagrams of key components of the main reaction zone of the present invention, wherein Figure 4(a) is a schematic diagram of the hydrocyclone and Figure 4(b) is a schematic diagram of the magnetically stabilized grid. Among them, 101-reaction device body, 102-water inlet, 103-vent outlet, 104-pressure relief microporous disk, 104-01-micropore, 104-02-first central hole; 105-cyclone disk, 105-01-guide channel, 105-02-second central hole, 106-microbubble shearing disk, 106-01, 106-02, 106-03-shearing teeth, 107-dosing port, 1 08-Premixed swirl cone, 109-Rotating shaft, 110-Swirl converter, 110-01-Swirl converter blade, 110-02-Swirl converter center hole, 111-Magnetic stabilized grid, 111-01-Grid hole, 111-02-Third center hole, 112-Helmholtz coil, 113-Effluent triangular weir, 114-Effluent trough, 115-Inclined plate settling unit, 116-Effluent outlet, 117-Central column. Detailed Implementation

[0025] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0026] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a multi-stage cyclone-magnetically stabilized heterogeneous Fenton oxidation wastewater treatment device. Figure 1 The device includes a reaction body 101, an inlet 102, a vent outlet 103, a pressure-relieving microporous disk 104, a vortex disk 105, a microbubble shear disk 106, a dosing port 107, a premixed vortex cone 108, a rotating shaft 109, a hydrocyclone 110, a magnetically stabilized grid 111, a Helmholtz coil 112, an effluent triangular weir 113, an effluent trough 114, an inclined plate settling unit 115, an effluent outlet 116, and a central column 117. The reaction body 101 preferably adopts a vertical tower-shaped structure, forming a premixed vortex zone, a main reaction zone, and an effluent separation zone from bottom to top, with the latter part of the main reaction zone being a deep oxidation zone. The inlet 102 is connected to the premixed vortex zone, the dosing port 107 is used for adding oxidants, acid-base adjusters, or catalysts, and the effluent triangular weir 113, effluent trough 114, and effluent outlet 116 are used for effluent collection and discharge.

[0028] The premixed swirl zone is located at the bottom of the main body 101 of the reaction device, and its lower part adopts an inverted cone structure to enhance the liquid flow convergence and swirl start-up effect. The premixed swirl zone is equipped with a premixed swirl cone 108, a pressure-relieving microporous disk 104, a swirl disk 105, a microbubble shear disk 106, and a rotating shaft 109. After the wastewater to be treated enters through the inlet 102, it achieves rapid mixing under the action of dissolved gas release, micro / nanobubble formation, and swirl shearing, thereby improving the dispersion uniformity of hydrogen peroxide and catalyst in the liquid phase.

[0029] As shown in Figures 3(a)-3(c), the key components of the premixed swirling zone include: a pressure-relieving microporous disk 104, micropores 104-01, and a first central hole 104-02; a swirling disk 105, a guide groove 105-01, and a second central hole 105-02; and a microbubble shearing disk 106, with concentrically distributed shearing teeth 106-01 to 106-03. The pressure-relieving microporous disk 104 is used to release dissolved air water to form fine bubbles, the swirling disk 105 is used to induce the liquid flow to generate a tangential velocity component, and the microbubble shearing disk 106 is used to further refine the bubbles. The three components work together to form a stable micro / nanobubble swirling premixed environment.

[0030] The main reaction zone is located above the premixed swirling zone, with the deep oxidation zone following it. Swirlers 110 and magnetically stabilized grids 111 are alternately arranged within the main reaction zone, with Helmholtz coils 112 positioned externally. Through the synergy of fluid dynamics and magnetic fields, efficient mass transfer and catalyst stabilization are achieved. The swirlers 110 continuously maintain tangential and turbulent flow, while the magnetically stabilized grids 111, under the influence of an external magnetic field, enhance the residence and uniform distribution of the magnetic catalyst, thus balancing the requirements of high mass transfer and low loss.

[0031] As shown in Figures 4(a) and 4(b), the key components of the main reaction zone include: a hydrocyclone 110, hydrocyclone blades 110-01, and a hydrocyclone central hole 110-02; a magnetically stabilized grid 111, grid holes 111-01, and a third central hole 111-02. The blades of the hydrocyclone 110 are preferably inclined to the horizontal plane to cut bubbles, enhance local turbulence, and maintain the fluidization state of the catalyst particles. The magnetically stabilized grid 111 is preferably a cylindrical structure, alternately stacked with the hydrocyclone 110. Its interior can form rhomboid channels or wavy three-dimensional channels to ensure fluid throughput and magnetic field depth, with the channel area accounting for more than 70%. Preferably, the thickness of the magnetically stabilized grid 111 is typically between 30-80 mm, depending on the reactor diameter, to ensure sufficient mechanical strength and magnetic field depth. A Helmholtz coil capable of generating an alternating magnetic field is installed on the outer wall of the reaction device at the position corresponding to the magnetic stabilizing grid 111. The Helmholtz coil is located on the outer wall of the reaction device and is installed directly opposite the magnetic stabilizing grid. Its electromagnetic coil adopts an intermittent working mode and can generate a pulsed magnetic field with adjustable intensity.

[0032] The effluent separation zone is equipped with an inclined plate settling unit 115 and an effluent triangular weir 113 to achieve efficient in-situ separation and reuse of the catalyst.

[0033] In one specific embodiment, the device of the present invention is used for the advanced treatment of leachate from a municipal solid waste landfill. The original biological treatment effluent had a COD concentration of 450–550 mg / L, high color, and poor biodegradability (B / C < 0.1), requiring further treatment to meet the emission standards (COD < 100 mg / L) of the "Standard for Pollution Control of Municipal Solid Waste Landfills" (GB16889-2024). The reactor body is made of carbon steel lined with PP material, with a total height of 5.5 m, a diameter of 1.8 m, and an effective volume of 12 m³. 3 The processing capacity is 50m³. 3 / d.

[0034] In this embodiment, the premixed swirling zone has a height of 1.0m and adopts an inverted conical structure with a cone angle of 60°; the main reaction zone has a height of 2.5m and contains three layers of cyclones and two layers of magnetically stabilized grids arranged alternately; the deep oxidation zone has a height of 1.2m; and the effluent separation zone has a height of 0.8m. The aeration rate of the micro / nano bubble system is 0–320 m³ / h. 3 / h, the average bubble size is about 80μm; the magnetic field system uses an electromagnetic coil, and the magnetic field strength is adjustable from 0 to 200mT.

[0035] The magnetic heterogeneous Fenton catalyst used is a Fe3O4·ZrO2·MOF composite catalyst with an average particle size of about 150 μm, a saturation magnetization of about 35 emu / g, and a specific surface area of ​​about 580 m². 2 / g, with an initial filling amount of 15% of the effective reactor volume. It should be noted that, without departing from the core idea of ​​this invention, other particulate catalysts with magnetic responsiveness and heterogeneous Fenton activity can also be used.

[0036] During operation, the landfill leachate effluent from the biological treatment process is first filtered through a 0.1mm bag filter to remove suspended solids before entering the equalization tank, where the pH is pre-adjusted to 5.0 (using a 10% sulfuric acid solution). Then, the micro-nano bubble aeration system is activated, controlling the air-to-water ratio at 4:1. The magnetic field system is then activated with a magnetic field strength of 80mT, and the circulation pump is turned on to form an internal circulation fluidization. Hydrogen peroxide is used in a 30% (w / w) solution, with two dosing points: 70% at the inlet of the premixed vortex zone and 30% at the deep oxidation zone. The total dosage is calculated based on a COD to H2O2 mass ratio of approximately 1:1.5 and adjusted according to changes in the influent COD.

[0037] During continuous operation, it is preferable to use an intelligent control system to automatically maintain the pH of the main reaction zone at 3.8–4.2 and the ORP value of the reaction system at 280–320 mV. The catalyst concentration is tracked by magnetic monitoring and the volume concentration of the catalyst is maintained at 12–15% (v / v) by a magnetic sensor to ensure stable operation of the device.

[0038] In a preferred embodiment, the intelligent control system includes a PLC controller and electrically connected to it a magnetic sensor, a catalyst reflux valve, and a magnetic field generator. The magnetic sensor is installed on the outer wall or inside the main reaction zone to monitor the change in magnetic permeability of the mixture in the reaction zone in real time. Since the magnetic permeability of the mixture is positively correlated with the solid content of the magnetic catalyst therein, the controller uses a PID control algorithm to automatically adjust the opening of the reflux valve on the catalyst reflux pipeline, or fine-tune the magnetic field strength of the Helmholtz coil, based on the deviation between a preset solid content range (e.g., 12%-15%) and the real-time magnetic permeability value, to increase or decrease the residence time of the catalyst in the main reaction zone, thereby dynamically maintaining the solid content within the target range. When the magnetic permeability is below the lower limit, the controller increases the opening of the reflux valve or strengthens the magnetic field; when the magnetic permeability is above the upper limit, it decreases the opening of the reflux valve or weakens the magnetic field.

[0039] The treatment results of this device after 30 consecutive days of operation are shown in Table 1: Table 1 Comparison of Treatment Effects

[0040] As shown in Table 1, when the influent COD is approximately 498 mg / L, the effluent COD can be reduced to approximately 78 mg / L, with a COD removal rate of approximately 84%. Compared with a traditional Fenton oxidation reactor of the same scale, the COD removal rate of this invention is increased by approximately 15-20%; BOD5 is reduced from 45 mg / L to 12 mg / L; color is reduced from 320 times to 25 times; total iron is approximately 0.85 mg / L; and catalyst loss is less than 3%. Compared with a traditional Fenton oxidation reactor of the same scale, the catalyst loss of this invention is reduced by approximately 60%.

[0041] The energy consumption per unit water volume of this invention is 1.8 kWh / m³. 3 Reagent consumption: H2O2 consumption 1.2 kg / kg COD, sulfuric acid consumption 0.15 kg / m³ 3 Catalyst loss: The average daily replenishment is approximately 0.8% of the initial fill volume; Operating cost: The cost per unit water treatment is approximately RMB 4.2 / m³. 3 (Including electricity costs, reagent costs, and catalyst loss). Compared with a conventional Fenton oxidation reactor of the same scale, the present invention improves COD removal rate by approximately 15-20%, H2O2 utilization rate by approximately 35%, reduces catalyst loss by approximately 60%, reduces sludge production by approximately 70%, and lowers operating costs by approximately 30%. Compared with a conventional Fenton oxidation reactor of the same scale, the present invention demonstrates better overall performance in terms of COD removal rate, hydrogen peroxide utilization rate, catalyst loss control, sludge reduction, and operating costs.

[0042] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A multi-stage cyclone-magnetically stabilized heterogeneous Fenton oxidation wastewater treatment device, characterized in that, The reactor body includes a vertical tower-shaped structure, which, from bottom to top, comprises an interconnected premixed swirl zone, a main reaction zone, and an effluent separation zone. The bottom of the premixed swirling zone is equipped with a rotary shearing micro-nano bubble aeration device for generating micro-nano bubbles and forming an initial swirling flow. The main reaction zone is alternately equipped with cyclones and magnetically stabilized grids, and the outer wall of the main body of the reaction device is provided with an external magnetic field generator for generating an alternating magnetic field at the position corresponding to the magnetically stabilized grid. The effluent separation zone is equipped with an inclined plate sedimentation unit and an effluent weir for in-situ separation of the catalyst.

2. The multi-stage cyclone-magnetically stabilized heterogeneous Fenton oxidation wastewater treatment device according to claim 1, characterized in that, The rotary shearing micro / nano bubble aeration device includes a premixed swirl cone, a pressure-relieving microporous disk, a fixed swirl disk, and a high-speed rotating microbubble shear disk arranged sequentially from bottom to top; wherein, the pressure-relieving microporous disk and the fixed swirl disk are located inside the cone of the premixed swirl cone, and the microbubble shear disk is located above the cone opening of the premixed swirl cone.

3. The multi-stage cyclone-magnetically stabilized heterogeneous Fenton oxidation wastewater treatment device according to claim 2, characterized in that, The pressure-relieving microporous disk is connected to the water inlet located at the bottom of the main body of the reaction device, and the water inlet is externally connected to a dissolved gas tank and a water pump.

4. The multi-stage cyclone-magnetically stabilized heterogeneous Fenton oxidation wastewater treatment device according to claim 1, characterized in that, The main reaction zone is provided with at least three layers of the cyclone separators and at least two layers of the magnetically stabilized grids. The cyclone separators are provided with guide vanes at a set angle to the horizontal plane to cut bubbles, enhance turbulence and maintain the fluidization state of catalyst particles.

5. The multi-stage cyclone-magnetically stabilized heterogeneous Fenton oxidation wastewater treatment device according to claim 1, characterized in that, The magnetically stabilized grid has a cylindrical structure and is arranged alternately with the cyclone separator; the interior of the magnetically stabilized grid forms a rhomboid channel or a wave-shaped three-dimensional channel.

6. The multi-stage cyclone-magnetically stabilized heterogeneous Fenton oxidation wastewater treatment device according to claim 1, characterized in that, The external magnetic field generator is a Helmholtz coil, which is installed on the outer wall of the main body of the reaction device, facing the magnetically stabilized grid. The Helmholtz coil operates in an intermittent mode to generate a pulsed magnetic field with adjustable intensity.

7. A method for treating wastewater using the apparatus according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1. Pre-treat the wastewater and adjust its pH to an acidic range; Step 2. The wastewater is introduced into the premixed cyclone zone, and an oxidant and a magnetic heterogeneous Fenton catalyst are added into the device; Step 3. Turn on the rotary micro-nano bubble aeration device and the external magnetic field generator to allow the catalyst to fully contact and mix with the wastewater under the action of fluidization and magnetic stabilization; Step 4. The mixture is introduced into the main reaction zone, where a heterogeneous Fenton oxidation reaction is carried out under the synergistic effect of the hydrocyclone, magnetically stabilized grid and external magnetic field generator. Step 5. The reaction mixture enters the effluent separation zone, where the catalyst is separated by the inclined plate sedimentation unit. The separated catalyst is returned to the main reaction zone, and the separated clear water is discharged through the effluent weir.

8. The method according to claim 7, characterized in that, The oxidant is added at multiple points. Oxidant addition points are set at the inlet of the premixed swirl zone and the rear section of the main reaction zone, and the ratio of the amount of oxidant added to the premixed swirl zone to the amount added to the main reaction zone is 70:

30.

9. The method according to claim 7, characterized in that, In step 4, the distribution and residence time of the catalyst in the main reaction zone are controlled by adjusting the magnetic field strength of the external magnetic field generator.

10. The method according to claim 7, characterized in that, In step 4, the volume concentration of the catalyst in the main reaction zone is maintained at 12%-15% by the intelligent control system, the pH during the reaction process is 3.8-4.2, and the ORP value of the reaction system is 280-320mV.

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