Energy-saving and environment-friendly multiple sewage treatment device and use method thereof

Abstract

The application relates to the technical field of sewage treatment, and discloses an energy-saving and environment-friendly multiple sewage treatment device and a use method, which comprise a processor and two baffles installed on the processor, the two baffles divide the interior of the processor into a mixing zone, a reaction zone and a sedimentation zone, a plurality of groups of reaction tubes are installed between the two baffles and are communicated with the mixing zone and the sedimentation zone at two ends. 3+ The moving catalyst enrichment zone formed by the ferromagnetic fluid driven by the traveling wave magnetic field, the pulse magnetic field and Fe 2+ / Fe 2+ circulation generates a large number of hydroxyl radicals, an auxiliary electric field supplements H2O2 and Fe in situ, and the three cooperate to continuously and efficiently generate ·OH, so that organic pollutants can be quickly mineralized, chemical oxygen demand can be significantly reduced, toxic and harmful organic matters can be degraded, and chroma can be eliminated.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to an energy-saving and environmentally friendly multi-stage wastewater treatment device and its usage method. Background Technology

[0002] With the rapid development of industrialization and urbanization, industries such as dyeing and printing, pharmaceuticals, chemicals, and coking generate large amounts of high-concentration, recalcitrant organic wastewater. This wastewater is characterized by high chemical oxygen demand (COD), strong biological toxicity, and poor biodegradability, making it difficult for conventional biological treatment methods to directly meet discharge standards. To address this type of wastewater, multiple treatment processes combining various methods are often required, such as "coagulation sedimentation, biological treatment, and advanced oxidation" or "advanced oxidation, flocculation, and membrane separation." However, existing multiple treatment processes typically consist of several independent unit devices connected in series, resulting in common problems such as large footprint, high equipment investment, complex operation and management, and a lack of synergistic effects between units.

[0003] Fenton oxidation, a type of advanced oxidation technology, is widely used in the pretreatment or advanced treatment of this type of wastewater because it generates highly oxidizing hydroxyl radicals (·OH). Traditional homogeneous Fenton processes typically require operation under strongly acidic conditions to maintain the Fe content in the solution. 2+ The activity and stability of Fe are affected, and a large amount of alkali solution must be used to restore the pH to neutral after the reaction, resulting in a large consumption of acid and alkali; at the same time, Fe 2+ High dosage leads to the generation of large amounts of iron-containing sludge after the reaction, resulting in high subsequent treatment costs and a high risk of secondary pollution. To overcome these drawbacks, researchers have developed improved technologies such as heterogeneous Fenton, electro-Fenton, and magnetic Fenton.

[0004] Magnetic Fenton technology utilizes an external magnetic field applied in a reactor to influence Fe. 3+ / Fe 2+ The circulation promotes the yield of ·OH, and the magnetic catalyst is attracted by a magnetic field to assist in its recovery. However, existing magnetic Fenton devices still have the following shortcomings:

[0005] Uncontrollable spatial distribution of catalyst: The magnetic field distribution is fixed, and it is impossible to actively control the movement trajectory and enrichment position of the magnetic catalyst in the reactor. The catalyst is usually in a uniform suspension state, and it is difficult to form a local high-concentration catalytic zone according to the pollutant concentration gradient, which leads to limited catalytic efficiency.

[0006] Fe 3+ / Fe 2+ Low circulation rate: magnetic field on Fe 3+ The reduction-promoting effect mainly relies on ion diffusion and mass transfer, lacking high instantaneous power excitation methods, Fe 3+ Converted to Fe 2+ The rate of formation is still relatively slow, limiting the continued generation of ·OH.

[0007] To address the above problems, this invention provides an energy-saving and environmentally friendly multi-stage wastewater treatment device and its usage method. Summary of the Invention

[0008] To address the aforementioned shortcomings of existing technologies, this invention provides an energy-saving and environmentally friendly multi-stage wastewater treatment device and its usage method, which employs traveling wave magnetic field drive, pulse magnetic field enhancement, electrochemical assistance, and in-situ circulation technology to treat wastewater.

[0009] The present invention provides the following technical solution: an energy-saving and environmentally friendly multi-stage sewage treatment device, comprising a processor and two baffles installed inside the processor, wherein the two baffles divide the interior of the processor into a mixing zone, a reaction zone and a sedimentation zone, and a plurality of reaction tubes are installed between the two baffles, wherein the two ends of the reaction tubes are respectively connected to the mixing zone and the sedimentation zone.

[0010] The processor's reaction zone inner wall is equipped with a traveling wave magnetic field component, and the processor's mixing zone is equipped with a ferromagnetic fluid injection port and a wastewater inlet. The traveling wave magnetic field component is used to generate a positive traveling wave magnetic field that moves along the water flow direction to drive the ferromagnetic fluid to migrate and form a moving high-concentration catalyst enrichment zone; and to generate a reverse traveling wave magnetic field that moves against the water flow direction to push the ferromagnetic fluid enriched at the end back to the mixing zone as a whole, thereby achieving in-situ self-circulation without an external pump.

[0011] The processor has an intercepting magnetic field component at the end of the inner wall of the reaction zone, which is used to apply a reverse traveling wave magnetic field in a fixed direction to form a magnetic field barrier and trap the ferrofluid at the end of the reaction zone.

[0012] Several sets of the aforementioned reaction tubes are fitted with pulsed magnetic field components to generate pulsed magnetic fields, thereby enhancing the Fe on the surface of the ferrofluid. 3+ / Fe 2+ It circulates and generates hydroxyl radicals, while simultaneously correcting the waveform distortion of the traveling wave magnetic field;

[0013] Several sets of reaction tubes have an auxiliary electric field on their surface, which is connected to an external DC power supply. The main products generated are H₂O₂ and Fe. 2+ This provides a continuous supply of reactants for ferrofluids driven by traveling wave magnetic fields;

[0014] The processor has a drain outlet at the top and a sedimentation outlet at the bottom of the sedimentation zone, and the flocculent Fe(OH)3 is precipitated through the sedimentation zone.

[0015] Preferably, the traveling wave magnetic field assembly includes multiple independent excitation coils arranged axially at equal intervals within the reaction zone of the processor, and a pulse power supply and controller electrically connected to each coil; the pulse power supply and controller generate a positive traveling wave magnetic field moving from the mixing zone to the sedimentation zone by sequentially delaying and triggering each coil; and generate a reverse traveling wave magnetic field moving from the sedimentation zone to the mixing zone by reversing the delaying and triggering each coil.

[0016] Preferably, the intercepting magnetic field assembly includes several sets of independent excitation coils disposed at the end of the inner wall of the reaction zone, and a pulse power supply and controller electrically connected to each coil; in the end interception mode, the pulse power supply and controller continuously apply a reverse traveling wave current opposite to the direction of water flow to the coils, generating a reverse traveling wave magnetic field with a fixed direction, forming a magnetic field interception barrier, intercepting and enriching the ferrofluid at the end of the reaction zone, and circulating in conjunction with the reverse traveling wave magnetic field of the traveling wave magnetic field assembly.

[0017] Preferably, the pulsed magnetic field assembly includes an auxiliary pulsed magnetic field coil sleeved on the outer wall of each reaction tube, and a pulse power supply and controller set together with the traveling wave magnetic field assembly. The pulse power supply and controller control the triggering sequence of the auxiliary pulsed magnetic field coil to be staggered from the triggering sequence of the traveling wave magnetic field assembly, so that the two do not generate magnetic fields simultaneously. The auxiliary pulsed magnetic field coil is used to generate a pulsed magnetic field to correct the waveform distortion of the traveling wave magnetic field and locally enhance the Fe on the surface of the ferrofluid. 3+ / Fe 2+ cycle.

[0018] Preferably, the auxiliary electric field includes multiple anode thin-film electrodes and multiple cathode thin-film electrodes, as well as a DC power supply electrically connected to each thin-film electrode; the anode and cathode thin-film electrodes are respectively attached to the outer walls of different reaction tubes, and the polarities of the thin-film electrodes on adjacent reaction tubes are alternately distributed; the reaction tubes are made of conductive material and are kept energized when the traveling wave magnetic field assembly executes the forward traveling wave mode; they are de-energized when the reverse feedback mode is executed; the auxiliary electric field is used to generate H2O2 and Fe in situ within the reaction tubes. 2+ It provides a continuous supply of reactants to the ferrofluid and de-energizes it in reverse feed mode to prevent bubbles from interfering with the reverse migration of the ferrofluid.

[0019] An energy-saving and environmentally friendly multi-stage wastewater treatment method is described below:

[0020] Step 1: The wastewater to be treated is introduced into the mixing zone through the wastewater inlet, and ferromagnetic fluid is simultaneously injected into the mixing zone through the ferromagnetic fluid injection inlet; the pH of the influent is adjusted to 5.0-6.5, and hydrogen peroxide is continuously added;

[0021] Step 2: The traveling wave magnetic field assembly is activated to generate a positive traveling wave magnetic field that moves from the mixing zone to the precipitation zone. This drives the ferrofluid in the mixing zone into the reaction tube and migrates forward, forming a moving high-concentration catalyst enrichment zone. During the positive traveling wave operation, the pulse magnetic field assembly is triggered during the pulse gap of the traveling wave magnetic field assembly, applying a pulse magnetic field to the ferrofluid to enhance Fe... 3+ / Fe 2+ The reaction cycle generates hydroxyl radicals; simultaneously, an auxiliary electric field is maintained, resulting in the in-situ generation of H2O2 and Fe within the reaction tube. 2+ To continuously replenish reactants for the reaction, organic pollutants in wastewater are oxidized and degraded under the action of hydroxyl radicals.

[0022] Step 3: When the ferrofluid migrates with the water flow to the end of the reaction zone, the intercepting magnetic field component applies a reverse traveling wave magnetic field in a fixed direction at the end of the reaction zone to form a magnetic field barrier, which intercepts and enriches the ferrofluid at the end of the reaction zone.

[0023] Step 4: After a period of time, turn off the power supply of the auxiliary electric field, so that the traveling wave magnetic field component generates a reverse traveling wave magnetic field that moves from the sedimentation zone to the mixing zone. At the same time, the pulse magnetic field component is synchronously triggered with the traveling wave magnetic field to enhance the reverse thrust, pushing the ferrofluid enriched at the end back to the mixing zone as a whole, realizing the pump-free in-situ self-circulation of the ferrofluid. After the return is completed, repeat steps 2 to 4.

[0024] Step 5: The treated wastewater enters the sedimentation zone, where the flocculent Fe(OH)3 settles by gravity and is discharged from the bottom sedimentation outlet, while the supernatant is discharged from the top drain outlet.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The traveling wave magnetic field drives the ferrofluid to form a moving catalyst enrichment zone, and the pulsed magnetic field excites Fe 3+ / Fe 2+ The cycle generates a large number of hydroxyl radicals, and the auxiliary electric field replenishes H2O2 and Fe in situ. 2+ The three elements work synergistically to ensure the continuous and efficient generation of ·OH, which can rapidly mineralize organic pollutants, significantly reduce chemical oxygen demand, degrade toxic and harmful organic matter, and eliminate color. Simultaneously, Fe... 3+ The Fe(OH)3 flocs generated by hydrolysis adsorb phosphate, achieving deep phosphorus removal.

[0027] (2) The forward traveling wave drives the ferrofluid to migrate, and the end intercepting magnetic field forms a barrier to enrich it. The reverse traveling wave pushes it back to the mixing zone as a whole. No external circulation pump, pipeline or magnetic separator is needed throughout the process. The ferrofluid loss rate is low and the external iron salt replenishment is greatly reduced.

[0028] (3) In-situ generation of H2O2 and Fe by auxiliary electric field 2+Pulsed magnetic field accelerates Fe 3+ / Fe 2+ The circulation significantly reduces the amount of external reagents required; the entire reaction operates under near-neutral conditions, eliminating the need for strong acid-base reversion and drastically reducing acid-base consumption.

[0029] (4) The pulsed magnetic field component can correct the distortion of the traveling wave waveform and ensure the uniformity of the magnetic field; the parallel structure of multiple reaction tubes facilitates modular amplification and can be flexibly adapted to different treatment scales by increasing or decreasing the number of reaction tubes; it is suitable for various industrial wastewater containing recalcitrant organic matter and toxic inhibitors. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the internal structure of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of the reaction tube of the present invention.

[0032] In the diagram: 1. Processor; 2. Baffle; 3. Intercepting magnetic field assembly; 4. Mixing zone; 5. Reaction zone; 6. Sedimentation zone; 7. Reaction tube; 8. Traveling wave magnetic field assembly; 9. Ferromagnetic fluid inlet; 10. Auxiliary electric field; 11. Pulsed magnetic field assembly; 12. Wastewater inlet; 13. Drainage outlet; 14. Sedimentation outlet. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. In order to keep the following description of the embodiments of this disclosure clear and concise, detailed descriptions of known functions and known components are omitted to avoid unnecessarily obscuring the concept of the present invention.

[0034] Please see Figure 1 and Figure 2 The present invention discloses an energy-saving and environmentally friendly multi-stage wastewater treatment device, comprising a horizontal cylindrical processor 1. The processor 1 is divided into a mixing zone 4, a reaction zone 5, and a sedimentation zone 6 by two parallel baffles 2. Multiple parallel reaction tubes 7 are installed between the two baffles 2. The two ends of the reaction tubes 7 pass through through holes on the baffles 2 and are connected to the mixing zone 4 and the sedimentation zone 6, respectively. The inner wall of the reaction tubes 7 is smooth and made of conductive material.

[0035] Multiple independent excitation coils are equidistantly arranged along the axial direction on the outer wall of reaction zone 5, forming a traveling wave magnetic field assembly 8. At the end of the inner wall of reaction zone 5, near the sedimentation zone, several sets of excitation coils are arranged, forming an intercepting magnetic field assembly 3. An auxiliary pulse magnetic field coil is fitted onto the outer wall of each reaction tube 7, forming a pulse magnetic field assembly 11. An annular thin-film electrode is also attached to the outer wall of each reaction tube 7, with alternating polarities on adjacent reaction tubes 7, and connected to an external DC power supply, forming an auxiliary electric field 10. The side wall of mixing zone 4 is provided with a ferromagnetic fluid inlet 9 and a wastewater inlet 12. The top of sedimentation zone 6 is provided with a drain outlet 13, and the bottom with a sedimentation outlet 14. Through the coordinated operation of these components, pump-free self-circulation of the ferromagnetic fluid and efficient catalytic oxidation treatment of wastewater are achieved.

[0036] Multiple independent excitation coils of the traveling wave magnetic field assembly 8 are arranged at equal intervals along the axial direction of the reaction zone 5 and fixed to the inner wall of the reaction zone 5 of the processor 1. The pulse power supply and controller are electrically connected to each group of coils and can independently control the energizing sequence, current intensity, and pulse width of each group of coils. When a positive traveling wave magnetic field is required, the controller triggers each coil sequentially with a delay from the mixing zone 4 to the sedimentation zone 6, causing the magnetic field peak to move along the water flow direction. The moving speed is set to be slightly less than the flow velocity of the sewage in the reaction tube 7, thereby driving the ferrofluid to be dragged forward by the traveling wave magnetic field and forming a moving high-concentration catalyst enrichment zone. When a reverse traveling wave magnetic field is required, the controller triggers each coil sequentially with a delay in the opposite direction, causing the magnetic field peak to move towards the mixing zone 4, pushing the ferrofluid enriched at the end back to the mixing zone as a whole, realizing in-situ self-circulation without an external pump.

[0037] The intercepting magnetic field component 3 consists of several sets of independent excitation coils located at the end of the inner wall of the reaction zone 5. These coils are also electrically connected to the pulse power supply and controller, and can be controlled independently of the traveling wave magnetic field component 8. During forward traveling wave operation, when the ferrofluid migrates with the water flow to the end of the reaction zone, the controller activates the intercepting mode, continuously applying a reverse traveling wave current opposite to the water flow direction to the coil, generating a fixed-direction reverse traveling wave magnetic field. The strength of this magnetic field can be independently adjusted as needed, usually set to be higher than the magnetic field strength at the end of the traveling wave magnetic field component 8, thereby forming a strong magnetic barrier at the end of the reaction zone. The ferrofluid is firmly captured at this barrier, unable to escape with the effluent, and gradually accumulates in the end region; while the Fe(OH)3 flocs produced by the reaction, due to their extremely weak magnetic response, are unaffected by the magnetic field and continue to settle in the sedimentation zone with the water flow, achieving automatic separation of the ferrofluid and reaction products. After a period of enrichment, the end intercepting magnetic field remains operational, preparing for subsequent reverse return.

[0038] The pulsed magnetic field assembly 11 consists of auxiliary pulsed magnetic field coils sleeved on the outer wall of each reaction tube 7, arranged at equal intervals along the axial direction of the reaction tube 7. One or more sets of coils can be installed on each reaction tube 7. The auxiliary pulsed magnetic field coils share a set of pulse power supply and controller with the traveling wave magnetic field assembly 8, and different timing pulse outputs are achieved through time-division control.

[0039] When the traveling wave magnetic field component 8 is in forward traveling wave mode, the controller briefly triggers the auxiliary pulse magnetic field coil during the trigger interval between two adjacent traveling wave coils, causing it to generate a pulse magnetic field with high instantaneous power. The peak intensity of this pulse magnetic field is lower than that of the traveling wave magnetic field component 8, but the pulse width is narrower and the instantaneous power is higher, which can induce an electron transition effect on the ferrofluid surface, significantly accelerating Fe... 3+ To Fe 2+ The reduction of the ferrofluid surface increases the catalytic cycle rate several times.

[0040] Simultaneously, the pulsed magnetic field can correct local distortions in the traveling wave waveform caused by factors such as the arrangement of the reaction tube bundles and the tube wall material, making the distribution of the traveling wave magnetic field more uniform throughout the entire reaction zone. In the end-interception mode, the controller synchronously triggers the auxiliary pulsed magnetic field coil and the coil of the intercepting magnetic field component 3, further enhancing the strength of the reverse intercepting magnetic field and ensuring that the ferrofluid is completely trapped. In the reverse feedback mode, the auxiliary pulsed magnetic field coil and all coils of the traveling wave magnetic field component 8 are synchronously triggered, jointly generating a reverse thrust that moves from the sedimentation zone to the mixing zone, pushing the ferrofluid enriched at the end back to the mixing zone as a whole, achieving efficient in-situ self-circulation. Because the triggering sequence of the auxiliary pulsed magnetic field coil and the traveling wave magnetic field component is strictly staggered or synchronized only in specific modes, the two will not produce magnetic field superposition interference, ensuring the stable operation of the system.

[0041] The auxiliary electric field 10 includes annular thin-film electrodes attached to the outer wall of each reaction tube 7. A portion of the reaction tubes 7 are fitted with anode thin-film electrodes, and the other portion with cathode thin-film electrodes. The electrodes on adjacent reaction tubes 7 are alternately distributed in polarity, forming a transverse electric field. The reaction tube 7 itself is made of conductive material, preferably stainless steel. The thin-film electrodes are tightly bonded to the tube wall using conductive adhesive. An external DC power supply is connected to the anode and cathode busbars, respectively.

[0042] When the traveling wave magnetic field component 8 operates in both the forward traveling wave mode and the terminal interception mode, the DC power supply remains energized. Current is conducted through the pipe wall to the water inside the pipe, generating a uniform electric field within the reaction tube. Under the influence of this electric field, an oxygen reduction reaction occurs in the cathode region to generate H₂O₂, and an iron dissolution reaction occurs in the anode region to generate Fe. 2+ Or trace amounts of Fe leached from the stainless steel pipe wall 2+ This continuously replenishes the oxidant and catalyst for the Fenton reaction. Since the ferrofluid itself is also Fe3O4, the Fe generated by the auxiliary electric field...2+ Fe excited by pulsed magnetic field 3+ / Fe 2+ The cycle forms a complementary relationship, ensuring that there are sufficient active iron ions throughout the entire reaction zone.

[0043] When the traveling wave magnetic field component 8 switches to the reverse feedback mode, the controller automatically cuts off the DC power supply of the auxiliary electric field. At this time, the electrode no longer generates current, and the hydrogen evolution reaction on the cathode surface stops, thus preventing hydrogen bubbles from adhering to the surface of the ferrofluid and reducing its magnetic responsiveness. This ensures that the reverse traveling wave can efficiently push the ferrofluid back to the mixing zone.

[0044] The traveling wave magnetic field component 8 drives the ferrofluid to migrate within the reaction tube 7, forming a moving high-concentration catalyst enrichment zone; the pulsed magnetic field component 11 is triggered in the traveling wave gap, exciting the Fe on the surface of the ferrofluid. 3+ / Fe 2+ The cycle generates highly oxidizing hydroxyl radicals (·OH); H₂O₂ and Fe₂ are generated in situ under an auxiliary electric field of 10. 2+ The reaction continuously replenishes reactants; the three work synergistically to generate a large amount of hydroxyl radicals (·OH), which indiscriminately attack and mineralize organic pollutants, thereby reducing chemical oxygen demand (COD), degrading toxic and harmful organic matter, and eliminating color; simultaneously, the Fe produced by the reaction 3+ At near-neutral pH, it hydrolyzes to generate Fe(OH)3 flocs, which adsorb phosphates in wastewater and are discharged through sedimentation zone 6, thus achieving phosphorus removal.

[0045] The following describes in detail the operation method of an energy-saving and environmentally friendly multi-stage wastewater treatment device of the present invention, taking into account the specific structure of the above-mentioned device.

[0046] Step 1: Mixing and Injection

[0047] The wastewater to be treated is continuously introduced into the mixing zone 4 through the wastewater inlet 12. At the same time, ferromagnetic fluid Fe3O4 nanoparticle suspension is continuously or intermittently injected into the mixing zone 4 through the ferromagnetic fluid injection inlet 9. The pH of the wastewater in the mixing zone is adjusted to 5.0-6.5 by the pH adjustment unit, and H2O2 is continuously added by the hydrogen peroxide dosing unit, so that the ferromagnetic fluid, wastewater and H2O2 are initially mixed in the mixing zone 4. The ferromagnetic fluid is driven by the water flow to pass through the through holes on the baffle 2 and enter the inlet of each reaction tube 7.

[0048] Step 2: Forward Traveling Wave Driven and Catalytic Oxidation

[0049] The pulse power supply and controller of the traveling wave magnetic field component 8 are activated, causing it to sequentially trigger each independent excitation coil in the direction from mixing zone 4 to sedimentation zone 6 with a delay, generating a positive traveling wave magnetic field that moves along the water flow direction. The moving speed of the traveling wave magnetic field is set to be slightly less than the flow velocity of the sewage in the reaction tube 7. Under the dragging effect of the magnetic field, the ferrofluid is drawn in and migrates forward along the reaction tube 7, forming a moving high-concentration catalyst enrichment zone in the tube, actively matching the pollutant concentration distribution.

[0050] During forward traveling wave operation, the pulse power supply and controller of the pulse magnetic field assembly 11 briefly triggers the auxiliary pulse magnetic field coils fitted on the outer wall of each reaction tube 7 during the time interval between the triggering of two adjacent coils of the traveling wave magnetic field assembly 8, generating a pulse magnetic field with high instantaneous power. The peak intensity of this pulse magnetic field is lower than that of the traveling wave magnetic field, but the instantaneous power is higher, which can excite the electronic transitions on the surface of Fe3O4 particles, thus converting Fe... 3+ Rapid reduction to Fe 2+ This allows the Fe on the surface of the ferrofluid to be... 3+ / Fe 2+ The cycle rate increases several times, generating a large number of hydroxyl radicals (·OH).

[0051] Simultaneously, the auxiliary electric field 10 remains energized during the positive traveling wave. The alternating anode and cathode thin-film electrodes on adjacent reaction tubes generate a transverse electric field under the influence of the DC power supply, which is transmitted to the water inside the tubes through the conductive reaction tube walls. In the cathode region, dissolved oxygen is reduced to H₂O₂; in the anode region, trace amounts of the stainless steel tube wall dissolve or oxidize to form Fe. 2 + This continuously replenishes the reactants for the Fenton reaction. Organic pollutants in wastewater are oxidized and decomposed under the action of hydroxyl radicals, with large, recalcitrant molecules breaking down into smaller molecules or mineralizing into CO2 and H2O.

[0052] Step 3: End-point interception and enrichment

[0053] When the ferrofluid migrates with the water flow to the end of reaction zone 5, the controller continuously applies a reverse traveling wave current opposite to the water flow direction to the coil of the intercepting magnetic field component 3, generating a fixed-direction reverse traveling wave magnetic field, forming a strong magnetic barrier. The ferrofluid Fe3O4 is firmly captured at this barrier and cannot continue to advance with the effluent, gradually accumulating at the end. The Fe(OH)3 flocs generated during the reaction process, due to their extremely weak magnetic response, are unaffected by the intercepting magnetic field and continue to flow with the water into sedimentation zone 6, thereby achieving automatic separation of the ferrofluid and reaction products.

[0054] Step 4: Reverse feedback and in-situ circulation

[0055] Once the amount of ferrofluid enriched at the end reaches a specified quantity, the controller first cuts off the DC power supply of the auxiliary electric field 10 to stop the electrode from working, thus preventing hydrogen bubbles generated at the cathode from adhering to the surface of the ferrofluid and reducing its magnetic responsiveness. Then, the controller causes the traveling wave magnetic field assembly 8 to sequentially trigger all coils in the reverse direction from the precipitation zone 6 to the mixing zone 4, generating a reverse traveling wave magnetic field.

[0056] Simultaneously, the auxiliary pulsed magnetic field coil of the pulsed magnetic field component 11 is triggered synchronously with the traveling wave magnetic field component, jointly enhancing the reverse thrust. The ferrofluid enriched at the end moves as a whole towards the mixing zone 4 under the drive of the reverse traveling wave, and is eventually pushed back into the mixing zone 4 to mix with fresh wastewater and replenished ferrofluid, before re-entering the reaction tube 7 to participate in the next cycle of catalytic oxidation. After the return process is complete, the controller restores the power supply to the auxiliary electric field 10 and switches back to the forward traveling wave mode, repeating steps two through four to achieve in-situ closed-loop circulation of the ferrofluid without external pumps or pipes.

[0057] Step 5: Sludge-water separation and discharge

[0058] After treatment, the wastewater flows out of the reaction pipe 7 and enters the sedimentation zone 6. In the sedimentation zone, the hydraulic velocity decreases significantly, and the Fe(OH)3 flocs settle by gravity to the bottom of the zone. They are periodically discharged from the bottom sedimentation outlet 14 for dewatering and transportation or further resource utilization. The supernatant overflows the overflow weir at the top of the sedimentation zone and is discharged from the drain outlet 13. Depending on the effluent quality requirements, a conventional magnetic flocculation sedimentation unit can be added after the sedimentation zone, with the addition of small amounts of magnetic powder, PAC, and PAM to further remove residual suspended solids and total phosphorus, ensuring the effluent meets discharge standards or is reused.

[0059] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. An energy-saving and environmentally friendly multi-stage wastewater treatment device, characterized in that: Includes a processor (1) and two baffles (2) installed inside the processor (1), and the two baffles (2) divide the interior of the processor (1) into a mixing zone (4), a reaction zone (5) and a precipitation zone (6). Several sets of reaction tubes (7) are installed between the two baffles (2), and the two ends of the reaction tubes (7) are connected to the mixing zone (4) and the precipitation zone (6) respectively. The inner wall of the reaction zone (5) of the processor (1) is provided with a traveling wave magnetic field component (8), and the mixing zone (4) of the processor (1) is provided with a ferromagnetic fluid injection port (9) and a sewage inlet (12). The traveling wave magnetic field component (8) is used to generate a positive traveling wave magnetic field that moves along the water flow direction to drive the ferromagnetic fluid to migrate and form a moving high-concentration catalyst enrichment zone. And generate a reverse traveling wave magnetic field that moves against the direction of water flow, pushing the ferrofluid enriched at the end back to the mixing zone (4), realizing in-situ self-circulation without external pumps; The processor (1) has an intercepting magnetic field component (3) at the end of the inner wall of the reaction zone (5) for applying a reverse traveling wave magnetic field in a fixed direction to form a magnetic field barrier and trap the ferrofluid at the end of the reaction zone (5). Several sets of the reaction tubes (7) are fitted with pulsed magnetic field components (11) for generating pulsed magnetic fields to enhance the Fe on the surface of the ferrofluid. 3+ / Fe 2+ It circulates and generates hydroxyl radicals, while simultaneously correcting the waveform distortion of the traveling wave magnetic field; Several sets of reaction tubes (7) have an auxiliary electric field (10) on their surface, which is connected to an external DC power supply, and mainly generate H2O2 and Fe. 2+ This provides a continuous supply of reactants for ferrofluids driven by traveling wave magnetic fields; The processor (1) has a drain outlet (13) at the top and a sedimentation outlet (14) at the bottom of the sedimentation zone (6), through which the flocculent Fe(OH)3 is precipitated.

2. The energy-saving and environmentally friendly multi-stage wastewater treatment device according to claim 1, characterized in that: The traveling wave magnetic field assembly (8) includes multiple independent excitation coils arranged axially at equal intervals in the reaction zone (5) of the processor (1), and a pulse power supply and controller electrically connected to each coil; the pulse power supply and controller generate a positive traveling wave magnetic field moving from the mixing zone (4) to the sedimentation zone (6) by sequentially delaying the triggering of each coil; and generate a reverse traveling wave magnetic field moving from the sedimentation zone (6) to the mixing zone (4) by reversing the delaying triggering of each coil.

3. The energy-saving and environmentally friendly multi-stage wastewater treatment device according to claim 1, characterized in that: The intercepting magnetic field component (3) includes several sets of independent excitation coils disposed at the end of the inner wall of the reaction zone (5), as well as a pulse power supply and controller electrically connected to each coil; in the end interception mode, the pulse power supply and controller continuously apply a reverse traveling wave current opposite to the direction of water flow to the coil, generating a reverse traveling wave magnetic field with a fixed direction, forming a magnetic field interception barrier, intercepting and enriching the ferrofluid at the end of the reaction zone (5), and circulating in conjunction with the reverse traveling wave magnetic field component (8).

4. The energy-saving and environmentally friendly multi-stage wastewater treatment device according to claim 1, characterized in that: The pulsed magnetic field assembly (11) includes an auxiliary pulsed magnetic field coil sleeved on the outer wall of each reaction tube (7), and a pulse power supply and controller in the same set as the traveling wave magnetic field assembly (8). The pulse power supply and controller control the triggering sequence of the auxiliary pulsed magnetic field coil to be staggered from the triggering sequence of the traveling wave magnetic field assembly (8), so that the two do not generate magnetic fields at the same time. The auxiliary pulsed magnetic field coil is used to generate a pulsed magnetic field to correct the waveform distortion of the traveling wave magnetic field and locally enhance the Fe on the surface of the ferrofluid. 3+ / Fe 2+ cycle.

5. The energy-saving and environmentally friendly multi-stage wastewater treatment device according to claim 1, characterized in that: The auxiliary electric field (10) includes multiple anode thin-film electrodes and multiple cathode thin-film electrodes, as well as a DC power supply electrically connected to each thin-film electrode; the anode thin-film electrodes and cathode thin-film electrodes are respectively attached to the outer walls of different reaction tubes (7), and the polarity of the thin-film electrodes on adjacent reaction tubes is alternately distributed; the reaction tubes (7) are made of conductive material and are kept energized when the traveling wave magnetic field assembly (8) performs the forward traveling wave mode; and are de-energized when the reverse feedback mode is performed; the auxiliary electric field (10) is used to generate H2O2 and Fe in situ within the reaction tubes (7). 2+ It provides a continuous supply of reactants to the ferrofluid and de-energizes it in reverse feed mode to prevent bubbles from interfering with the reverse migration of the ferrofluid.

6. A method of using an energy-saving and environmentally friendly multi-stage wastewater treatment device, characterized in that, The energy-saving and environmentally friendly multi-stage wastewater treatment device according to any one of claims 1-5 is operated as follows: Step 1: The wastewater to be treated is introduced into the mixing zone (4) through the wastewater inlet (12), and ferromagnetic fluid is injected into the mixing zone (4) through the ferromagnetic fluid injection inlet (9); the pH of the influent is adjusted to 5.0-6.5, and hydrogen peroxide is continuously added; Step 2: The traveling wave magnetic field assembly (8) is activated to generate a positive traveling wave magnetic field that moves from the mixing zone (4) to the precipitation zone (6), driving the ferrofluid in the mixing zone into the reaction tube (7) and forward to form a moving high-concentration catalyst enrichment zone; during the positive traveling wave operation, the pulse magnetic field assembly (11) is triggered in the pulse gap of the traveling wave magnetic field assembly (8) to apply a pulse magnetic field to the ferrofluid to enhance Fe 3+ / Fe 2+ The reaction cycle generates hydroxyl radicals; simultaneously, an auxiliary electric field (10) is maintained to keep the circuit energized, and H2O2 and Fe are generated in situ within the reaction tube (7). 2+ To continuously replenish reactants for the reaction, organic pollutants in wastewater are oxidized and degraded under the action of hydroxyl radicals. Step 3: When the ferrofluid migrates with the water flow to the end of the reaction zone (5), the intercepting magnetic field component (3) applies a fixed-direction reverse traveling wave magnetic field to the end of the reaction zone to form a magnetic field barrier, which intercepts and enriches the ferrofluid at the end of the reaction zone (5). Step 4: After a period of time, turn off the power supply of the auxiliary electric field (10) so that the traveling wave magnetic field component (8) generates a reverse traveling wave magnetic field that moves from the sedimentation zone (6) to the mixing zone (4). At the same time, the pulse magnetic field component (11) is triggered synchronously with the traveling wave magnetic field to enhance the reverse thrust, pushing the ferrofluid enriched at the end back to the mixing zone (4) as a whole, realizing the pump-free in-situ self-circulation of the ferrofluid. After the return is completed, repeat steps 2 to 4. Step 5: The treated wastewater enters the sedimentation zone (6), where the flocculent Fe(OH)3 settles by gravity and is discharged from the bottom sedimentation outlet (14), while the supernatant is discharged from the top drain outlet (13).

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