Sewage treatment method based on reinforcement of composite magnetic nanoparticles

Abstract

The invention discloses a sewage treatment method based on reinforcement of composite magnetic nanoparticles, and belongs to the technical field of sewage treatment, and the sewage treatment method comprises the following steps: 1, pretreatment: intercepting large-particle-size floating objects in wastewater by using a grid, and stirring by using an adjusting tank to uniformly mix water; in the second step, composite magnetic nanoparticles are added into the pretreated wastewater, and nitrogen and phosphorus adsorption and electric energy collection and storage are achieved at the same time; 3, separation: separating the composite particles through a magnetic separation device, and further purifying the wastewater through a sedimentation tank; 4, regeneration: forming an electric field by utilizing the collected electric energy, desorbing particles by combining with a neutral solution of an antibiotic degradation product, and recycling after cleaning; 5, standard reaching and energy consumption balance are carried out, the wastewater is disinfected, the water quality is monitored, the stirring speed and the power supply proportion are adjusted in a linkage mode, and standard emission and energy consumption self-balance are ensured. The method does not need to depend on microorganisms, particles and energy recycling, the treatment efficiency is high, and the operation cost is low.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a wastewater treatment method based on composite magnetic nanoparticle reinforcement. Background Technology

[0002] With the rapid development of the pharmaceutical and medical industries, the discharge of combined antibiotic and nitrogen-phosphorus wastewater has been continuously increasing. This type of wastewater widely originates from pharmaceutical factories, hospitals, and other similar settings, and contains both antibiotics and nitrogen and phosphorus nutrients, forming a complex pollution system of toxic organic matter and nutrients. Antibiotics can damage the biodiversity of aquatic ecosystems and may induce the development of drug-resistant genes in microorganisms; nitrogen and phosphorus, on the other hand, easily induce eutrophication in water bodies, threatening drinking water safety and ecological balance. Currently, countries around the world are imposing increasingly stringent requirements on the discharge of this type of wastewater. How to achieve efficient synergistic treatment of antibiotics and nitrogen and phosphorus has become a core challenge that urgently needs to be overcome in the field of wastewater treatment.

[0003] Existing treatment technologies are mainly divided into biological and physicochemical methods. Biological methods rely on microbial metabolism to remove nitrogen and phosphorus, but antibiotics strongly inhibit the activity of functional microorganisms such as denitrifying bacteria and polyphosphate-accumulating bacteria, resulting in unstable treatment effects or even failure. In physicochemical methods, traditional magnetic nanoparticles can only adsorb nitrogen and phosphorus and lack the ability to degrade antibiotics, requiring the addition of an oxidation unit, which is lengthy. Existing piezoelectric catalysis technology is only for single organic matter and requires external energy supply, which cannot simultaneously treat nitrogen and phosphorus or recover energy. In addition, most adsorbent regeneration relies on acid-base desorption, which is prone to secondary pollution and has high energy consumption. Summary of the Invention

[0004] To overcome the above shortcomings, this invention provides a wastewater treatment method based on composite magnetic nanoparticle enhancement, which aims to improve the current simultaneous nitrogen and phosphorus removal technology, which is susceptible to fluctuations in influent water quality and temperature, resulting in large fluctuations in nitrogen and phosphorus removal rates, and requires a large amount of chemical reagents, leading to high energy consumption and high operating costs.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a wastewater treatment method based on composite magnetic nanoparticle reinforcement, comprising the following steps:

[0006] S1. For complex wastewater containing drug residue, packaging fragments, and fluctuating concentrations of nitrogen, phosphorus, and antibiotics, an adjustable screen with a spacing of 10-50mm is used to intercept large-diameter floating objects. The wastewater is then introduced into an equalization tank with an effective volume of 10%-30% of the daily treatment capacity. The tank is stirred for 15-30 minutes by an in-tank agitator to ensure that the concentrations of nitrogen, phosphorus, and antibiotics in the wastewater are mixed evenly, and to control the fluctuation of water quality to no more than 15%, thus providing stable influent conditions for subsequent reactions.

[0007] S2. Based on the total concentration of nitrogen, phosphorus, and antibiotics in the pretreated wastewater, 10-100 mg / L of Fe3O4@ZnO-graphene composite magnetic nanoparticles are precisely added through a dosing device. In a reaction tank equipped with a stirrer, mechanical vibration is generated by stirring at 50-200 r / min, which triggers the piezoelectric effect of ZnO. The antibiotic degradation rate is ≥90%. At the same time, graphene adsorbs nitrogen and phosphorus simultaneously. Fe3O4 is used as an electrode to collect 1-5V piezoelectric current and store it in a battery. The process of degradation, adsorption, and power generation is completed in 30-120 min.

[0008] S3. The mixture after the above reaction is introduced into a magnetic separation device with a magnetic field strength of 100-1000mT to separate the composite magnetic nanoparticles. The magnetically separated wastewater is then sent to a sedimentation tank for 1-3 hours to remove the remaining suspended solids and unseparated particles, ensuring the clarity of the wastewater.

[0009] S4. The separated composite particles are fed into a sealed desorption reactor with titanium alloy electrodes. A weak electric field of 50-100V / m is formed by the piezoelectric current stored in the battery. The neutral solution of antibiotic degradation products in the adsorption reaction module is used as the desorbent. Desorption is carried out at a temperature of 20-60℃ for 15-25 minutes. After desorption, the composite magnetic particles are washed to remove residual desorbent. The composite magnetic particles are then returned to the adsorption reaction module for recycling.

[0010] S5. After disinfection, the effluent from the sedimentation tank is monitored in real time by an online monitoring device to track nitrogen and phosphorus concentrations, pH value, turbidity, and antibiotic residues. Simultaneously, the power consumption recorder controls the system in conjunction with the following: if the piezoelectric current is <1V, the stirring speed of the reaction tank is automatically increased to 180-200r / min to enhance the piezoelectric effect; if the battery power is sufficient for 30 minutes of energy consumption of the magnetic separation device, the external power grid supply ratio is reduced to below 30%; the wastewater is discharged only after meeting the standards. If the standards are not met, the wastewater is sent back to the adsorption reaction module, and steps S2-S5 are repeated until all parameters of the wastewater meet the discharge standards.

[0011] Preferably, the outlet of the pretreatment module's regulating tank is equipped with a concentration monitor to collect nitrogen, phosphorus, and antibiotic concentration data in real time; if the concentration fluctuation of any pollutant is detected to be greater than 15%, the stirring time is automatically extended by 5-10 minutes or the influent flow rate is adjusted to ensure the stability of the influent water quality.

[0012] Preferably, the preparation process of the Fe3O4@ZnO-graphene composite magnetic nanoparticles is as follows: Fe3O4 nanoparticles are dispersed in an ethanol-water mixture (volume ratio 1:1), Zn(NO3)2・6H2O and urea are added, and a ZnO coating layer is generated by hydrothermal reaction at 80-90℃; then a graphene oxide solution is added, and the mixture is calcined at 500-600℃ for 1-2 hours under a N2 atmosphere to reduce graphene and form a core-shell and sheet-like composite structure.

[0013] Preferably, in the Fe3O4@ZnO-graphene composite magnetic nanoparticles, ZnO is uniformly coated on the surface of Fe3O4 in the form of 10-20 nm nanocrystals, and graphene sheet-like structures are interspersed in the interparticle gaps. The surface hydroxyl and carboxyl groups are associated with PO4. 3- Forming coordinate bonds, for PO4 3- The adsorption selectivity is Cl - It is 8-10 times more effective and can reduce interference from coexisting ions.

[0014] Preferably, the Fe3O4@ZnO-graphene composite magnetic nanoparticles have a particle size of 50-80 nm, and the mass ratio of Fe3O4, ZnO and graphene is 3:2:5-4:3:3.

[0015] Preferably, the magnetic field strength uniformity error on the surface of the magnetic cylinder of the separation module is ≤5%, and the magnetic cylinder rotation speed is 10-20 r / min; a polyurethane scraper is provided below the magnetic cylinder to scrape the adsorbed composite particles into the collection tank to avoid particle accumulation.

[0016] Preferably, the sedimentation tank outlet of the separation module is equipped with a stainless steel interceptor with a 5μm aperture to further trap tiny composite particles; the bottom of the sedimentation tank is equipped with a sludge discharge pipe, which discharges sludge once every 4 hours, with the discharge volume being 5%-8% of the tank volume, to avoid sludge accumulation.

[0017] Preferably, the electrode spacing of the desorption reactor of the regeneration module is 10-20cm, and the stability of the piezoelectric current input is controlled by a constant voltage power supply. During the desorption process, the nitrogen and phosphorus concentrations of the desorbent are monitored in real time. When the desorption rate is less than 85%, the desorption time is automatically extended by 5-10 minutes or the electric field strength is increased to 120V / m to ensure the regeneration effect.

[0018] Preferably, after cleaning, the cleaning device of the regeneration module monitors the particle size distribution using a laser particle size analyzer. If the particle size variation coefficient is greater than 20%, it is determined that the particles are agglomerated. 0.01-0.05% sodium hexametaphosphate solution is added, and the particles are stirred at a speed of 200-300 r / min for 5 min to redisperse them, ensuring the recyclability of the particles.

[0019] Preferably, the energy consumption recorder of the effluent module is linked with the stirrer of the adsorption reaction module and the magnetic separator of the separation module for control: the piezoelectric current is given priority to the magnetic separator, and the remaining power is stored. When the battery power is less than 20%, the stirring speed is increased to 180-200 r / min to supplement the power generation. If the power supply is still insufficient, the external power grid is activated to provide auxiliary power supply, so as to achieve dynamic energy balance.

[0020] The present invention has the following beneficial effects:

[0021] 1. This invention relies on the piezoelectric catalytic function of Fe3O4@ZnO-graphene composite particles. The degradation of antibiotics by ZnO can be triggered by mechanical vibration generated by stirring the reaction tank, without the need for an additional oxidation treatment unit. Moreover, the entire treatment system adopts a physicochemical closed-loop design, which does not rely on any microorganisms, thus avoiding the risk of antibiotics inhibiting functional microorganisms from the source and ensuring stable and controllable denitrification and phosphorus removal effects. To address the high energy consumption problem, the piezoelectric current is collected by the Fe3O4 component in the composite particles and stored in the battery to provide energy for subsequent magnetic separation, desorption and other stages, reducing dependence on the external power grid and achieving self-balancing of system energy consumption. At the same time, the regeneration stage uses a neutral solution of antibiotic degradation products as a desorbent to replace traditional acid and alkali reagents, which not only avoids secondary pollution, but also saves energy and costs in acid and alkali preparation and transportation, significantly reducing the operating burden.

[0022] 2. This invention has excellent resource utilization efficiency. The Fe3O4@ZnO-graphene composite particles can be recycled after desorption and cleaning, which greatly reduces the one-time consumption of adsorbent and lowers material costs. Moreover, the particles can simultaneously achieve antibiotic degradation and nitrogen and phosphorus adsorption. Compared with the traditional segmented process of first oxidizing and degrading antibiotics and then adsorbing and removing nitrogen and phosphorus, there is no need to split the processing flow, which greatly shortens the overall processing cycle and improves processing efficiency.

[0023] 3. In this invention, the adsorption catalysis module can adjust the dosage of composite particles according to the concentration of antibiotics, nitrogen and phosphorus in the wastewater to ensure the treatment effect; the effluent module can control the stirring speed and the external power supply ratio through linkage to adapt to the energy demand under different working conditions; this dynamic adjustment capability enables it to cope with antibiotic and nitrogen and phosphorus composite wastewater generated in different scenarios such as pharmaceutical plants and hospitals, and has a wide range of applications. Attached Figure Description

[0024] Figure 1 This is a flowchart of a wastewater treatment method based on composite magnetic nanoparticle reinforcement proposed in this invention;

[0025] Figure 2 This is a flowchart illustrating the energy recovery process of a wastewater treatment method based on composite magnetic nanoparticles reinforced according to the present invention.

[0026] Figure 3 This is a system module diagram of a wastewater treatment method based on composite magnetic nanoparticle reinforcement proposed in this invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Reference Figure 1-3 The present invention provides an embodiment of a wastewater treatment method based on composite magnetic nanoparticle reinforcement, comprising the following steps:

[0029] Step 1: For complex wastewater containing drug residues, packaging fragments, and fluctuating concentrations of nitrogen, phosphorus, and antibiotics generated in pharmaceutical factories, hospitals, and other similar settings, the wastewater is first introduced into the pretreatment module. A stainless steel bar screen is used to intercept large-diameter floating particles such as drug residues and packaging fragments in the wastewater. A 0.2-0.3 MPa backwashing device is activated at the bottom of the bar screen every 2 hours to prevent clogging. The intercepted waste residue is transported to the sludge treatment unit through pipelines. The wastewater filtered by the bar screen is then introduced into an equalization tank with an effective volume of 10%-30% of the daily treatment capacity. A paddle mixer with a rotation speed of 30-60 r / min is installed in the tank and stirred for 15-30 minutes to ensure that the concentrations of nitrogen, phosphorus, and antibiotics in the wastewater are uniformly mixed. An online concentration monitoring instrument is installed at the outlet of the equalization tank to collect real-time data on the concentrations of nitrogen, phosphorus, and antibiotics. If any pollutant concentration fluctuation is detected to be >15%, the stirring time is automatically extended by 5-10 minutes or the influent flow rate is adjusted to ensure that the fluctuation range of the pretreated water quality is ≤15%, providing stable influent conditions for subsequent adsorption and catalytic reactions.

[0030] Step 2: The pretreated wastewater is transported to the adsorption reaction module. Based on the total concentrations of nitrogen, phosphorus, and antibiotics fed back by the online concentration monitor, 10-100 mg / L of Fe3O4@ZnO-graphene composite magnetic nanoparticles are precisely added through a dosing device equipped with a flow metering pump. The particle size is 50-80 nm, and the mass ratio of Fe3O4, ZnO, and graphene is 3:2:5-4:3:3. ZnO is uniformly coated on the surface of Fe3O4 in the form of 10-20 nm nanocrystals, and graphene sheet structures are interspersed in the interparticle gaps. The surface hydroxyl, carboxyl groups, and PO4 groups are present. 3- Forming coordinate bonds, for PO4 3-The adsorption selectivity is 8-10 times that of Cl⁻, which can reduce interference from coexisting ions. The wastewater after adding the particles is sent to a reaction tank equipped with a stirrer. The stirring speed is set according to the pollutant concentration, generally 50-200 r / min. The mechanical vibration generated by stirring triggers the piezoelectric effect of ZnO, improving the antibiotic degradation rate. At the same time, graphene, with its ultra-large specific surface area of ​​2000-2500 m² / g, simultaneously adsorbs nitrogen and phosphorus. Fe3O4 is used as a conductive electrode to collect the 1-5V piezoelectric current generated by ZnO through the electrode plate at the bottom of the reaction tank and store it in the system's matching battery through wires. Wastewater indicators are monitored in real time during the reaction to ensure that the simultaneous process of antibiotic degradation, nitrogen and phosphorus adsorption, and piezoelectric power generation is completed after 30-120 minutes of reaction.

[0031] Step 3: The mixture after the adsorption-catalytic reaction is transported to the separation module. The mixture first enters the magnetic separator, which has a magnetic field strength of 100-1000 mT on the surface of the magnetic cylinder and a rotation speed of 10-20 r / min. A polyurethane scraper is installed below the magnetic cylinder, with a gap of 0.1-0.2 mm between the scraper and the surface of the magnetic cylinder. The composite particles adsorbed on the surface of the magnetic cylinder are scraped off into the collection tank. The particles in the collection tank are transported to the subsequent regeneration module by a screw conveyor. The wastewater after magnetic separation is sent to the sedimentation tank, where it is settled for 1-3 hours to remove the remaining suspended solids and small particles that were not magnetically separated. The outlet of the sedimentation tank is equipped with a stainless steel interceptor with a 5μm aperture to further trap small composite particles. A sludge discharge pipe is installed at the bottom of the sedimentation tank, and sludge is discharged once every 4 hours, with a discharge volume of 5%-8% of the tank volume, to avoid sludge accumulation. The clarified wastewater after sedimentation is transported to the post-treatment module, while the sludge enters the sludge treatment unit.

[0032] Step 4: The composite particles collected by magnetic separation are sent to the regeneration module. The composite particles first pass through a vibrating screen with a vibration frequency of 30-50Hz and a pore size of 0.1mm to remove surface-adhered sludge impurities. The undersized impurities are transported to the sludge treatment unit, while the clean particles on the screen fall into a temporary storage tank with a stirring function to prevent particle agglomeration. The particles in the temporary storage tank are then pumped to a closed desorption reactor equipped with titanium alloy electrodes (electrode spacing 10-20cm). Simultaneously, a neutral solution (pH 6.5-7.5) of antibiotic degradation products collected in the adsorption reaction module is introduced as a desorbent. After the desorbent level covers the particles, the reactor electrodes are connected to a battery. A piezoelectric current is input through a constant voltage power supply to form a weak electric field of 50-100V / m inside the reactor. The desorption temperature is controlled at 20-60℃, and the desorption time is 15-25min. During the desorption process, the nitrogen and phosphorus concentrations in the desorption liquid are monitored in real time using an online ion monitor. If the nitrogen and phosphorus desorption rate is <85%, the desorption process is considered complete. The desorption time is automatically extended by 5-10 minutes or the electric field strength is increased to 120V / m to ensure a desorption rate ≥90%. The desorbed particles and desorption liquid are then fed into a cleaning device and washed countercurrently with deionized water for 5-10 minutes to remove residual desorbent from the particle surface. The washed particles are then fed into a centrifugal dehydrator at 3000-5000 r / min to control the moisture content below 30%. Particle size distribution is monitored using a laser particle size analyzer. If the particle size variation coefficient is >20%, particle agglomeration is determined, and 0.01-0.05% sodium hexametaphosphate solution is automatically added, followed by stirring at 200-300 r / min for 5 minutes to redisperse the particles. Simultaneously, samples are taken for adsorption capacity testing to ensure that the particle adsorption capacity is ≥90% of the initial adsorption capacity. Qualified particles are returned to the addition device of the adsorption reaction module via an airflow pipeline for recycling, while unqualified particles are collected through a closed hopper and disposed of as general industrial solid waste by a qualified organization.

[0033] Step 5: The clarified wastewater from the sedimentation tank is sent to the effluent and discharge module. The disinfection method is selected based on the wastewater source: ozone disinfection is used for hospital wastewater, and ultraviolet disinfection is used for pharmaceutical wastewater to kill bacteria and viruses and meet hygiene discharge standards. The disinfected wastewater is temporarily stored in an intermediate tank. An online monitoring system at the tank outlet monitors nitrogen and phosphorus concentrations, pH value, turbidity, and antibiotic residues in real time, requiring antibiotic residues to be ≤0.1mg / L and nitrogen and phosphorus concentrations to meet local discharge standards. An energy consumption recorder monitors the battery charge in real time and works in conjunction with the agitator in the adsorption reaction module and the magnetic separator in the separation module to prioritize the supply of piezoelectric current to the magnetic separator. The remaining battery power is stored. If the battery power meets the energy consumption of the magnetic separation device, the external power grid supply ratio is automatically reduced to below 30%. If the battery power is less than 20%, the stirring speed of the adsorption catalytic reaction tank is increased to 180-200 r / min to enhance the ZnO piezoelectric effect and supplement power generation. If the power is still insufficient, the external power grid is activated to provide auxiliary power and achieve dynamic energy balance. If the wastewater quality meets the standards, it is discharged directly through the discharge pipe. If the water quality does not meet the standards, the wastewater is returned to the adsorption reaction module through the return pipe. The parameters such as the dosage of composite particles, stirring speed, and desorption temperature are adjusted simultaneously to repeat the adsorption catalysis, separation, and regeneration process until the wastewater meets the standards before being discharged.

[0034] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wastewater treatment method based on composite magnetic nanoparticle reinforcement, characterized in that: The steps include: S1. For complex wastewater containing drug residue, packaging fragments, and fluctuating concentrations of nitrogen, phosphorus, and antibiotics, an adjustable screen with a spacing of 10-50mm is used to intercept large-diameter floating objects. The wastewater is then introduced into an equalization tank with an effective volume of 10%-30% of the daily treatment capacity. The tank is stirred for 15-30 minutes by an in-tank agitator to ensure that the concentrations of nitrogen, phosphorus, and antibiotics in the wastewater are mixed evenly, and to control the fluctuation of water quality to no more than 15%, thus providing stable influent conditions for subsequent reactions. S2. Based on the total concentration of nitrogen, phosphorus, and antibiotics in the pretreated wastewater, 10-100 mg / L of Fe3O4@ZnO-graphene composite magnetic nanoparticles are precisely added through a dosing device. In a reaction tank equipped with a stirrer, mechanical vibration is generated by stirring at 50-200 r / min, which triggers the piezoelectric effect of ZnO. The antibiotic degradation rate is ≥90%. At the same time, graphene adsorbs nitrogen and phosphorus simultaneously. Fe3O4 is used as an electrode to collect 1-5V piezoelectric current and store it in a battery. The process of degradation, adsorption, and power generation is completed in 30-120 min. S3. The mixture after the above reaction is introduced into a magnetic separation device with a magnetic field strength of 100-1000mT to separate the composite magnetic nanoparticles. The magnetically separated wastewater is then sent to a sedimentation tank for 1-3 hours to remove the remaining suspended solids and unseparated particles, ensuring the clarity of the wastewater. S4. The separated composite particles are fed into a sealed desorption reactor with titanium alloy electrodes. A weak electric field of 50-100V / m is formed by the piezoelectric current stored in the battery. The neutral solution of antibiotic degradation products in the adsorption reaction module is used as the desorbent. Desorption is carried out at a temperature of 20-60℃ for 15-25 minutes. After desorption, the composite magnetic particles are washed to remove residual desorbent. The composite magnetic particles are then returned to the adsorption reaction module for recycling. S5. After disinfection, the effluent from the sedimentation tank is monitored in real time by an online monitoring device to track nitrogen and phosphorus concentrations, pH value, turbidity, and antibiotic residues. Simultaneously, the power consumption recorder controls the system in conjunction with the following: if the piezoelectric current is <1V, the stirring speed of the reaction tank is automatically increased to 180-200r / min to enhance the piezoelectric effect; if the battery power is sufficient for 30 minutes of energy consumption of the magnetic separation device, the external power grid supply ratio is reduced to below 30%; the wastewater is discharged only after meeting the standards. If the standards are not met, the wastewater is sent back to the adsorption reaction module, and steps S2-S5 are repeated until all parameters of the wastewater meet the discharge standards.

2. The wastewater treatment method based on composite magnetic nanoparticle reinforcement according to claim 1, characterized in that: The pretreatment module is equipped with a concentration monitor at the outlet of the regulating tank to collect nitrogen, phosphorus, and antibiotic concentration data in real time. If the concentration fluctuation of any pollutant is detected to be greater than 15%, the stirring time will be automatically extended by 5-10 minutes or the influent flow rate will be adjusted to ensure the stability of the influent water quality.

3. The wastewater treatment method based on composite magnetic nanoparticle reinforcement according to claim 1, characterized in that: The preparation process of the Fe3O4@ZnO-graphene composite magnetic nanoparticles is as follows: Fe3O4 nanoparticles are dispersed in an ethanol-water mixture (volume ratio 1:1), Zn(NO3)2・6H2O and urea are added, and a ZnO coating layer is generated by hydrothermal reaction at 80-90℃; then a graphene oxide solution is added, and the mixture is calcined at 500-600℃ for 1-2 hours under a N2 atmosphere to reduce the graphene and form a core-shell and sheet-like composite structure.

4. The wastewater treatment method based on composite magnetic nanoparticle reinforcement according to claim 3, characterized in that: In the Fe3O4@ZnO-graphene composite magnetic nanoparticles, ZnO is uniformly coated on the surface of Fe3O4 in the form of 10-20 nm nanocrystals, and graphene sheet-like structures are interspersed in the interparticle gaps. The surface of these nanoparticles contains hydroxyl and carboxyl groups, as well as PO4 groups. 3- Forming coordinate bonds, for PO4 3- The adsorption selectivity is Cl - It is 8-10 times more effective and can reduce interference from coexisting ions.

5. The wastewater treatment method based on composite magnetic nanoparticle reinforcement according to claim 4, characterized in that: The Fe3O4@ZnO-graphene composite magnetic nanoparticles have a particle size of 50-80 nm, and the mass ratio of Fe3O4, ZnO and graphene is 3:2:5-4:3:

3.

6. The wastewater treatment method based on composite magnetic nanoparticle reinforcement according to claim 1, characterized in that: The magnetic separator of the separation module has a magnetic field strength uniformity error of ≤5% on the surface of the magnetic cylinder and a cylinder rotation speed of 10-20 r / min. A polyurethane scraper is provided below the magnetic cylinder to scrape the adsorbed composite particles into the collection tank to avoid particle accumulation.

7. A wastewater treatment method based on composite magnetic nanoparticle reinforcement according to claim 6, characterized in that: The sedimentation tank outlet of the separation module is equipped with a stainless steel interceptor with a 5μm aperture to further trap tiny composite particles; the bottom of the sedimentation tank is equipped with a sludge discharge pipe, which discharges sludge once every 4 hours, with the discharge volume being 5%-8% of the tank volume, to avoid sludge accumulation.

8. The wastewater treatment method based on composite magnetic nanoparticle reinforcement according to claim 1, characterized in that: The electrode spacing of the desorption reactor in the regeneration module is 10-20cm, and the stability of the piezoelectric current input is controlled by a constant voltage power supply. During the desorption process, the nitrogen and phosphorus concentrations of the desorbent are monitored in real time. When the desorption rate is less than 85%, the desorption time is automatically extended by 5-10 minutes or the electric field strength is increased to 120V / m to ensure the regeneration effect.

9. A wastewater treatment method based on composite magnetic nanoparticle reinforcement according to claim 1, characterized in that: After cleaning, the cleaning device of the regeneration module monitors the particle size distribution using a laser particle size analyzer. If the particle size variation coefficient is greater than 20%, it is determined that the particles are agglomerated. 0.01-0.05% sodium hexametaphosphate solution is added and the particles are stirred at a speed of 200-300 r / min for 5 min to redisperse them, ensuring the recyclability of the particles.

10. A wastewater treatment method based on composite magnetic nanoparticle reinforcement according to claim 1, characterized in that: The energy consumption recorder of the water discharge module, together with the stirrer of the adsorption reaction module and the magnetic separator of the separation module, form a linkage control: the piezoelectric current is given priority to the magnetic separator, and the remaining power is stored. When the battery power is less than 20%, the stirring speed is increased to 180-200 r / min to supplement the power generation. If the power supply is still insufficient, the external power grid is started to provide auxiliary power supply, so as to achieve dynamic energy balance.

Images