Treatment system for removing microplastics in water

Abstract

The invention discloses a treatment system for removing micro-plastics in water. The treatment system comprises an adsorption enrichment unit, an effluent temporary storage unit, an advanced oxidation unit, a control unit, first dosing equipment, second dosing equipment and an artificial wetland unit, the adsorption enrichment unit comprises a water inlet tank, a first sand filter tank, an adsorption tank, a second sand filter tank and a water outlet tank along the water flow direction; the effluent temporary storage unit comprises a first temporary storage tank and a second temporary storage tank; the advanced oxidation unit comprises a treatment tank, and a stirrer and an ultraviolet lamp tube which are arranged in the treatment tank; the water outlet tank is communicated with the first temporary storage tank through a first water outlet pipe, and the first temporary storage tank discharges water into the constructed wetland unit through a first drainage pipe; the first dosing equipment is communicated with the water outlet tank through a first dosing pipe, and the second dosing equipment is communicated with the treatment tank through a second dosing pipe; the water inlet tank is communicated with the second temporary storage tank through a second water outlet pipe, the second temporary storage tank is communicated with the treatment tank through a third water outlet pipe, and the treatment tank discharges water into the constructed wetland unit through a second drainage pipe.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment and relates to the removal of microplastics, and in particular to a treatment system for removing microplastics in water. Background Art

[0002] Microplastics refer to plastic fragments and particles with a diameter of less than 5 mm. Plastic particles can be released into the natural environment through different pathways, such as urban runoff, air deposition, agricultural activities (i.e., the use of plastic film and biosolids applications), and daily discharge from wastewater treatment plants. Microplastics have gradually attracted attention as an emerging pollutant. Microplastics can migrate and transform in different environmental media, destroying the water ecology and soil structure. Due to the small size of microplastics, aquatic plants and animals can ingest microplastics through the food chain at different trophic levels, causing serious pollution persecution to organisms. In addition, microplastics also have a large specific surface area and can serve as carriers of harmful microorganisms and chemical pollutants in the environment. Toxic chemicals attached to plastic particles are also toxic to aquatic organisms and are eventually absorbed by the human body through the food chain, causing serious public health problems. Therefore, it is necessary to develop effective, scalable, and eco-friendly MPs removal technologies.

[0003] At present, effective methods for removing microplastics at home and abroad include membrane filtration, adsorption, chemically induced coagulation-flocculation-precipitation, improved oxidation process, magnetic separation, photolysis and photocatalysis. Although the above technologies are effective in removing MPs / NPs, certain parameters have become disadvantages of these removal technologies, namely sludge generation, equipment maintenance, energy consumption, low efficiency and secondary pollution. In contrast, adsorption is considered to be a very favorable and feasible method for effectively solving environmental problems. It has been proven to be efficient, direct, economically feasible, and able to regenerate adsorbent materials. The commonly used adsorbent in the prior art is activated carbon. Rapid sand filters integrated with activated carbon are a feasible treatment technology with good characteristics, including minimal maintenance and energy consumption. Although activated carbon has a large number of micropores, its pore size distribution is not uniform, and microplastics vary in size and shape. For microplastic particles of smaller size, activated carbon may not be able to effectively adsorb, resulting in poor removal effect. Activated carbon will gradually saturate and lose its adsorption capacity during use. Although its adsorption performance can be restored by thermal regeneration and other methods, the regeneration process may involve high energy consumption and cost. In addition, the currently available adsorption devices are columnar, with limited hydraulic retention time and limited efficiency in removing microplastics. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a treatment system for removing microplastics in water. The present invention can effectively prolong the hydraulic retention time and improve the removal efficiency of microplastics. At the same time, it can also elute the adsorption material in situ to avoid secondary pollution of the water body.

[0005] The technical solution of the present invention is achieved in this way:

[0006] A treatment system for removing microplastics in water comprises an adsorption and enrichment unit, an effluent temporary storage unit, an advanced oxidation unit, a control unit, a first dosing device, a second dosing device and an artificial wetland unit.

[0007] Along the water flow direction, the adsorption enrichment unit includes an inlet tank, a first sand filter tank, an adsorption tank, a second sand filter tank and an outlet tank. The adsorption tank is filled with biochar for adsorbing microplastics. The first sand filter tank and the second sand filter tank are both filled with quartz sand. The outlet water temporary storage unit includes a first temporary storage tank and a second temporary storage tank. The advanced oxidation unit includes a treatment tank and an agitator and an ultraviolet lamp arranged in the treatment tank.

[0008] The water outlet pool is connected to the first temporary storage pool through a first water outlet pipe, and the first temporary storage pool discharges water into the artificial wetland unit through a first drainage pipe.

[0009] The first dosing device is connected to the outlet pool through the first dosing pipe to add anhydrous ethanol into the outlet pool, and the second dosing device is connected to the treatment pool through the second dosing pipe to add persulfate into the treatment pool; the water inlet pool is connected to the second temporary storage pool through the second outlet pipe, the second temporary storage pool is connected to the treatment pool through the third outlet pipe, and the treatment pool is connected to discharge the water into the artificial wetland unit through the second drain pipe.

[0010] The first water outlet pipe, the second water outlet pipe, the third water outlet pipe, the first drainage pipe, the second drainage pipe, the first drug dosing pipe and the second drug dosing pipe are all provided with switch valves, and all the switch valves are connected to the control unit to control the opening and closing of the switch valves.

[0011] Furthermore, the water inlet tank, the first sand filter tank, the adsorption tank, the second sand filter tank and the water outlet tank are arranged side by side and closely adjacent to each other. The water in the water inlet tank enters the first sand filter tank through overflow. The pool wall between the first sand filter tank and the adsorption tank is at a certain height from the pool bottom to form a first water outlet. The water in the first sand filter tank enters the adsorption tank through the first water outlet. The water in the adsorption tank enters the second sand filter tank through overflow. The pool wall between the second sand filter tank and the water outlet tank is at a certain height from the pool bottom to form a second water outlet. The water in the second sand filter tank enters the water outlet tank through the second water outlet. In this way, the water in the water inlet tank is diverted and flows to the water outlet tank. 100-200 mesh filters are provided at the first water outlet and the second water outlet to close the first water outlet and the second water outlet.

[0012] Furthermore, the quartz sand particle size is 26-40 meshes, and the biochar is 60-100 mesh magnetically modified biochar.

[0013] Furthermore, the quartz sand is pretreated before filling, and the pretreatment steps are: first soak the quartz sand in a concentrated hydrochloric acid solution for 24 to 48 hours, and then wash it with water until it is neutral; then place the washed quartz sand in an oven and dry it at 60 to 80° C.; finally, soak the quartz sand in ultrapure water and boil it for 30 to 60 minutes to ensure complete saturation, and then fill it into the first sand filter and the second sand filter after cooling.

[0014] Furthermore, the preparation method of magnetically modified biochar is a co-precipitation pyrolysis method: FeCl3·6H2O and FeSO4·7H2O are added to deionized water in a molar ratio of 2:1. After complete dissolution, biochar is added and the pH of the mixture is adjusted to 12-13 with NaOH solution; the sample is placed on a magnetic stirrer and heated and stirred for 8-12 hours, and then aged overnight; after drying, it is placed in a tubular furnace, filled with N2 protection, heated to 500-700°C, and then kept warm for 2-3 hours; after the reaction is completed, it is cooled, and the ash impurities in the biochar are removed with deionized water, and finally dried at 60-80°C to obtain magnetically modified biochar.

[0015] Furthermore, the first temporary storage tank and the second temporary storage tank are both provided with a water level sensor and a bottom suction pump, and the water level sensor and the bottom suction pump are both connected to the control unit, so that when the water level sensor senses that the water level has reached a preset position, the corresponding bottom suction pump is turned on to pump out the water in the corresponding temporary storage tank.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The adsorption enrichment unit of the present invention adopts a baffled water flow mode to effectively extend the hydraulic retention time, and at the same time adds a biochar penetration layer to improve the efficiency of microplastic removal; at the same time, the adsorption material can be eluted in situ, and the advanced oxidation unit can accelerate the aging of microplastics in the eluent, thereby achieving efficient removal of microplastics and avoiding secondary pollution of the water body.

[0018] 2. The present invention sets a first sand filter and a second sand filter on both sides of the adsorption tank, which can effectively improve the overall efficiency and stability of the water treatment system. The sand filter can effectively remove suspended matter, silt and large particle impurities in the water, and prevent these solid particles from clogging the adsorbent, thereby ensuring that the adsorption tank can better remove microplastic particles in the water. By removing large particle impurities, the sand filter can also improve water quality, reduce the wear of the adsorbent, and extend its service life. In addition, the setting of the sand filter helps to reduce the load fluctuation of the adsorption tank and improve the treatment effect and stability of the entire water treatment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 -Schematic diagram of the structure of the present invention.

[0020] Figure 2-Schematic diagram of the structure of the adsorption enrichment unit.

[0021] Figure 3 -Schematic diagram of the structure of the effluent temporary storage unit.

[0022] Figure 4 -Schematic diagram of the structure of the advanced oxidation unit.

[0023] Among them: 1-adsorption enrichment unit; 2-water temporary storage unit; 3-advanced oxidation unit; 4-control unit; 5-first dosing equipment; 6-second dosing equipment; 7-support frame; 8-first water inlet pipe; 9-second water inlet pipe; 10-water inlet tank; 11-first sand filter tank; 12-adsorption tank; 13-second sand filter tank; 14-water outlet tank; 15-overflow plate; 16-water baffle; 17-first water outlet pipe; 18-first temporary storage tank; 19-water level sensor; 20-first bottom suction pump; 21-first drainage pipe; 22-first dosing pipe; 23-second water outlet pipe; 24-second temporary storage tank; 25-second bottom suction pump; 26-third water outlet pipe; 27-second dosing pipe; 28-ultraviolet lamp; 29-agitator; 30-second drainage pipe. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] See also Figure 1 , Figure 2 , Figure 3 and Figure 4 A treatment system for removing microplastics in water includes an adsorption and enrichment unit 1, a temporary storage unit for effluent 2, an advanced oxidation unit 3, a control unit 4, a first dosing device 5, a second dosing device 6 and an artificial wetland unit (not shown in the figure).

[0026] Along the water flow direction, the adsorption enrichment unit 1 includes an inlet pool 10, a first sand filter pool 11, an adsorption pool 12, a second sand filter pool 13 and an outlet pool 14. The adsorption pool 12 is filled with biochar for adsorbing microplastics. The first sand filter pool 11 and the second sand filter pool 13 are both filled with quartz sand.

[0027] The effluent temporary storage unit 2 includes a first temporary storage tank 18 and a second temporary storage tank 24, and the advanced oxidation unit 3 includes a treatment tank and an agitator 29 and an ultraviolet lamp 28 arranged in the treatment tank.

[0028] The water outlet pool 14 is connected to the first temporary storage pool 18 through the first water outlet pipe 17 , and the first temporary storage pool 18 discharges water into the artificial wetland unit through the first drainage pipe 21 .

[0029] The first dosing device 5 is connected to the outlet pool 14 through the first dosing pipe 22 to add anhydrous ethanol into the outlet pool 14, and the second dosing device 6 is connected to the treatment pool through the second dosing pipe 27 to add persulfate into the treatment pool; the water inlet pool 10 is connected to the second temporary storage pool 24 through the second outlet pipe 23, and the second temporary storage pool 24 is connected to the treatment pool through the third outlet pipe 26. The treatment pool discharges water into the artificial wetland unit through the second drain pipe 30.

[0030] The first water outlet pipe 17, the second water outlet pipe 23, the third water outlet pipe 26, the first drainage pipe 21, the second drainage pipe 30, the first drug dosing pipe 22 and the second drug dosing pipe 27 are all provided with switch valves, and all the switch valves are connected to the control unit 4 to control the opening and closing of the switch valves.

[0031] During specific implementation, the water inlet pool 10, the first sand filter pool 11, the adsorption pool 12, the second sand filter pool 13 and the water outlet pool 14 are arranged side by side and closely adjacent to each other. The water in the water inlet pool 10 overflows into the first sand filter pool 11 through the overflow plate 15. The pool wall between the first sand filter pool 11 and the adsorption pool 12 is at a certain height from the pool bottom to form a first water outlet. The water in the first sand filter pool 11 enters the adsorption pool 12 through the first water outlet. The water in the adsorption pool 12 overflows into the second sand filter pool 13 through the overflow plate 15. The pool wall between the second sand filter pool 13 and the water outlet pool 14 is at a certain height from the pool bottom to form a second water outlet. The water in the second sand filter pool 13 enters the water outlet pool 14 through the second water outlet. In this way, the water in the water inlet pool 10 is diverted and flows to the water outlet pool 14. 100-200 mesh filter screens are provided at the first water outlet and the second water outlet to close the first water outlet and the second water outlet. The pool walls corresponding to the first water outlet and the second water outlet form a water baffle 16 .

[0032] In specific implementation, the first temporary storage tank 18 and the second temporary storage tank 24 are both provided with a water level sensor 19 and a bottom suction pump (the bottom suction pump provided in the first temporary storage tank is the first bottom suction pump 20, and the bottom suction pump provided in the second temporary storage tank is the second bottom suction pump 25), and the water level sensor and the bottom suction pump are connected to a control unit, so that when the water level sensor senses that the water level reaches a preset position, the corresponding bottom suction pump is turned on to pump out the water in the corresponding temporary storage tank.

[0033] Here, the purpose of setting up the bottom suction pump and water level sensor is to ensure the stability of the liquid level in the first and second temporary storage tanks, ensure the uniform discharge of the liquid, and avoid problems such as overfilling, underfilling, and uneven water discharge in the pools, thereby improving the overall system operation efficiency and water quality control. If only the water outlet is set, the water level control may be inaccurate, the liquid in the pool cannot be effectively treated, and the stability and treatment effect of the system may be reduced.

[0034] As a polar solvent, anhydrous ethanol can change the interface characteristics between the adsorbent material and the microplastics, reduce the interfacial tension, make the microplastics more easily fall off the surface of the adsorbent material, and achieve in situ elution of the adsorbent material; the eluted water enters the advanced oxidation unit through the second temporary storage tank, and the sulfate radicals generated by the decomposition of persulfate under ultraviolet irradiation have extremely strong oxidizing properties, inducing accelerated aging of microplastics and achieving degradation of microplastics. In this embodiment, the first dosing device, the second dosing device and the control unit are arranged on the support frame 7.

[0035] In this way, the sewage treatment process: the sewage containing microplastics flows from the first water inlet pipe 8 into the second water inlet pipe 9. Since the diameter of the second water inlet pipe 9 is large, the water flow rate is slowed down, and the sewage accumulates in the water inlet pool 10, and overflows from the overflow plate 15 between the water inlet pool and the first sand filter pool into the first sand filter pool 11 to remove large suspended particles. Then the sewage flows into the adsorption pool 12 from the first water inlet at the lower end of the water baffle 16 between the first sand filter pool and the adsorption pool, and the biochar in the adsorption pool adsorbs the microplastics in the water body. Then the sewage overflows from the overflow plate 15 between the adsorption pool and the second sand filter pool into the second sand filter pool 13, and then is discharged into the outlet pool 14 through the second water inlet below the water baffle 16 between the second sand filter pool and the outlet pool, and is discharged into the first temporary storage pool 18 through the first outlet pipe 17, and is temporarily stored in the first temporary storage pool 18. When the water level sensor 19 in the first temporary storage tank senses that the water level reaches a preset position, the first bottom suction pump 20 in the first temporary storage tank lifts the purified sewage and discharges it into the artificial wetland unit through the first drainage pipe 21 for further treatment.

[0036] Backwashing process of adsorption enrichment unit: During backwashing, open the switch valves on the first dosing pipe 22 and the second outlet pipe 23, and close the switch valve on the first outlet pipe 17. The first dosing device 5 injects anhydrous ethanol into the outlet pool 14 through the first dosing pipe 22, and the anhydrous ethanol flows into the inlet pool 10 in the opposite direction of the water inlet, and is discharged into the second temporary storage pool 24 through the second outlet pipe 23, and is temporarily stored in the second temporary storage pool 24 to achieve elution of the adsorption enrichment unit. When the water level sensor 19 in the second temporary storage pool senses that the water level has reached the preset position, the second bottom suction pump 25 in the second temporary storage pool 24 lifts the eluted water and discharges it into the advanced oxidation unit 3 through the third outlet pipe 26. At this time, open the switch valve on the second dosing pipe 27, and close the valve on the second drain pipe 30. The second dosing device 6 doses persulfate through the second dosing pipe 27, and at room temperature and pressure, the persulfate is activated by the ultraviolet lamp 28, and the stirrer 9 stirs at a speed of 200 r / min to induce accelerated aging of microplastics. After the advanced oxidation is completed, the switch valve on the second drain pipe 30 is opened, and the eluted water is discharged into the artificial wetland unit through the second drain pipe 30.

[0037] In this embodiment, ultraviolet light is used to activate persulfate to induce accelerated aging of microplastics to avoid secondary pollution of water bodies. After irradiation with ultraviolet light for 40 hours, the weight loss rate (WL) of microplastics is about 38%.

[0038] In this way, the water flow mode of the adsorption enrichment unit adopts baffles to extend the hydraulic retention time, and at the same time, a biochar penetration layer is added to allow the microplastic particles in the water body to fully contact with the adsorption enrichment unit, thereby improving the removal efficiency. At the same time, the adsorption material can be eluted in situ during backwashing, and the advanced oxidation unit accelerates the aging of microplastics in the eluent, thereby achieving the purpose of efficiently removing microplastics and avoiding secondary pollution of the water body.

[0039] In a specific implementation, the particle size of the quartz sand is 26-40 meshes, the biochar is 60-100 mesh magnetically modified biochar, and correspondingly, the filter screens arranged at the first water outlet and the second water outlet are stainless steel screens of 100-200 meshes.

[0040] In specific implementation, the quartz sand is pretreated before filling, and the pretreatment steps are: first soak the quartz sand in concentrated hydrochloric acid solution for 24 to 48 hours, then wash with water until neutral; then place the washed quartz sand in an oven and dry at 60 to 80°C; finally, soak the quartz sand in ultrapure water and boil it for 30 to 60 minutes to ensure complete saturation, and then fill it into the first sand filter and the second sand filter after cooling. Pretreatment of the quartz sand here can effectively remove impurities and iron film on the surface of the quartz sand, and avoid secondary pollution of the water body by the quartz sand.

[0041] In specific implementation, the preparation method of magnetic modified biochar is: the preparation method of magnetic modified biochar is a co-precipitation pyrolysis method: FeCl3·6H2O and FeSO4·7H2O are added to deionized water in a molar ratio of 2:1, and after complete dissolution, biochar is added, and the pH of the mixture solution is adjusted to 12-13 with NaOH solution; the sample is placed on a magnetic stirrer and heated and stirred for 8-12 hours, and then aged overnight; after drying, it is placed in a tubular furnace, filled with N2 protection, heated to 500-700°C, and then kept warm for 2-3 hours; after the reaction is completed, it is cooled, and ash impurities in the biochar are removed with deionized water, and finally dried at 60-80°C to obtain magnetic modified biochar.

[0042] In this embodiment, FeCl3·6H2O and FeSO4·7H2O were added to 200 mL of deionized water in a molar ratio of 2:1. After they were completely dissolved, 10 g of biochar was added, and the pH of the mixture was adjusted to 12 with 1 M NaOH solution. The sample was placed on a magnetic stirrer and stirred for 12 h at 60 °C, and then aged overnight. After drying at 85 °C, it was placed in a tube furnace, filled with N2 protection, and heated at 5 °C·min -1The temperature was raised to 500 ° C, and then kept warm for 2 hours; after the reaction was completed, the reaction was cooled, and the ash impurities in the biochar were removed with deionized water, and finally dried at 80 ° C to obtain magnetically modified biochar. Compared with biochar, the magnetically modified biochar obtained here has a higher specific surface area, pore structure and additional active sites, which can significantly improve the removal efficiency of microplastics. 45 mg of biochar and magnetically modified biochar were added to two 50 mg / L polystyrene microplastic solutions (20 mL), respectively, and shaken in a dark environment for 24 hours. The removal rate of microplastics by biochar was 63.47%, and the adsorption amount was 14.11 mg / g. The removal rate of microplastics by magnetically modified biochar was 77.26%, and the adsorption amount was 17.17 mg / g.

[0043] Finally, it should be noted that the above embodiments of the present invention are only examples for illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes and modifications can be made based on the above description. It is impossible to list all implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A treatment system for removing microplastics in water, characterized in that: It includes an adsorption enrichment unit, a temporary storage unit for effluent, an advanced oxidation unit, a control unit, a first dosing device, a second dosing device and an artificial wetland unit; Along the water flow direction, the adsorption enrichment unit includes an inlet tank, a first sand filter tank, an adsorption tank, a second sand filter tank and an outlet tank, the adsorption tank is filled with biochar for adsorbing microplastics, and the first sand filter tank and the second sand filter tank are both filled with quartz sand; the outlet water temporary storage unit includes a first temporary storage tank and a second temporary storage tank, and the advanced oxidation unit includes a treatment tank and an agitator and an ultraviolet lamp arranged in the treatment tank; The water outlet pool is connected to the first temporary storage pool through a first water outlet pipe, and the first temporary storage pool discharges water into the artificial wetland unit through a first drainage pipe; The first dosing device is connected to the outlet pool through the first dosing pipe to add anhydrous ethanol into the outlet pool, and the second dosing device is connected to the treatment pool through the second dosing pipe to add persulfate into the treatment pool; the inlet pool is connected to the second temporary storage pool through the second outlet pipe, the second temporary storage pool is connected to the treatment pool through the third outlet pipe, and the treatment pool is connected to discharge water into the artificial wetland unit through the second drain pipe; The first water outlet pipe, the second water outlet pipe, the third water outlet pipe, the first drainage pipe, the second drainage pipe, the first drug dosing pipe and the second drug dosing pipe are all provided with switch valves, and all the switch valves are connected to the control unit to control the opening and closing of the switch valves.

2. A treatment system for removing microplastics in water according to claim 1, characterized in that: The water inlet tank, the first sand filter tank, the adsorption tank, the second sand filter tank and the outlet tank are arranged side by side and closely adjacent to each other. The water in the water inlet tank enters the first sand filter tank through overflow. The pool wall between the first sand filter tank and the adsorption tank is at a certain height from the pool bottom to form a first water outlet. The water in the first sand filter tank enters the adsorption tank through the first water outlet. The water in the adsorption tank enters the second sand filter tank through overflow. The pool wall between the second sand filter tank and the outlet tank is at a certain height from the pool bottom to form a second water outlet. The water in the second sand filter tank enters the outlet tank through the second water outlet. In this way, the water in the water inlet tank is diverted and flows to the outlet tank. 100-200 mesh filters are provided at the first water outlet and the second water outlet to close the first water outlet and the second water outlet.

3. A treatment system for removing microplastics from water according to claim 1 or 2, characterized in that: The particle size of the quartz sand is 26-40 meshes, and the biochar is 60-100 mesh magnetically modified biochar.

4. A treatment system for removing microplastics in water according to claim 3, characterized in that: The quartz sand is pretreated before filling, and the pretreatment steps are: first, soak the quartz sand in a concentrated hydrochloric acid solution for 24 to 48 hours, and then wash it with water until it is neutral; then place the washed quartz sand in an oven and dry it at 60 to 80° C.; finally, soak the quartz sand in ultrapure water and boil it for 30 to 60 minutes to ensure complete saturation, and then fill it into the first sand filter tank and the second sand filter tank after cooling.

5. A treatment system for removing microplastics in water according to claim 3, characterized in that: The preparation method of magnetically modified biochar is a co-precipitation pyrolysis method: FeCl3·6H2O and FeSO4·7H2O are added to deionized water in a molar ratio of 2:

1. After complete dissolution, biochar is added and the pH of the mixture is adjusted to 12~13 with NaOH solution; the sample is placed on a magnetic stirrer and heated and stirred for 8~12 h, and then aged overnight; after drying, it is placed in a tubular furnace, filled with N2 protection, heated to 500~700℃, and then kept warm for 2~3 h; after the reaction is completed, it is cooled, and the ash impurities in the biochar are removed with deionized water, and finally dried at 60~80℃ to obtain magnetically modified biochar.

6. A treatment system for removing microplastics in water according to claim 1 or 2, characterized in that: The first temporary storage tank and the second temporary storage tank are both provided with a water level sensor and a bottom suction pump, and the water level sensor and the bottom suction pump are both connected to a control unit, so that when the water level sensor senses that the water level reaches a preset position, the corresponding bottom suction pump is turned on to pump out the water in the corresponding temporary storage tank.

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