A water purification device and method for removing microplastics

Abstract

The present invention discloses a water purification device and method for removing microplastics, belonging to the technical field of water treatment. The water purification device for removing microplastics includes an electrochemically adsorbing and oxidizing unit and a self-cleaning desorbing unit; the electrochemically adsorbing and oxidizing unit includes a cylinder body, a cathode, a filter screen, an anode, three-dimensional granular electrodes, and a supporting layer; a sewage inlet for sewage containing microplastics to enter the electrochemically adsorbing and oxidizing unit is provided at the bottom side of the cylinder body; the cathode is sleeved inside the cylinder body, is a cylindrical stainless steel mesh electrode, and is spaced from the inner wall of the bottom of the cylinder body at the bottom; the filter screen is sleeved inside the cathode and is connected to the inner wall of the bottom of the cylinder body at the bottom; the anode is located in the middle of the cylinder body; the three-dimensional granular electrodes are arranged between the filter screen and the anode; the bottom of the supporting layer is provided with openings with a pore diameter smaller than the diameter of the three-dimensional granular electrodes. The present invention is applied to the removal of microplastics in water, realizes the efficient removal of microplastics in water without additional chemical agent input, and has the characteristics of being renewable and reusable.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to a water purification device and method for removing microplastics. Background Art

[0002] In recent years, microplastic pollution has attracted increasing public attention. Evidence shows that due to their chemical stability, microplastics may persist in the aquatic environment for thousands of years. As an emerging pollutant, they have caused serious economic losses to the marine ecosystem. Due to their large specific surface area, persistence and mobility, microplastics are more likely to adsorb organic chemical pollutants, heavy metals and harmful bacteria, resulting in an increasing impact on the water environment and a greater harm to human health. In particular, due to their low density and small size, microplastics are easily ingested by aquatic organisms after entering the water body, causing intestinal abrasion and blockage. The toxic chemical substances attached to the plastic particles also pose great harm to aquatic organisms and ultimately pass to humans through the food chain, causing serious health problems. However, due to the small size of microplastics and their low concentration in polluted water, effectively separating them remains an ongoing challenge.

[0003] Researchers have attempted to study different techniques for removing microplastics from water. Physical removal methods include adsorption, filtration, membrane separation, centrifugal separation, flotation, sol-gel separation, magnetic separation, electrocoagulation, etc. Existing physical removal techniques for microplastic treatment mainly include adsorption, coagulation, filtration and magnetic separation. Using the above methods, microplastics in polluted streams can be removed. Among them, a biochar filter integrates biochar into a sand filtration system and has a strong ability to remove and fix microplastic spheres. Combined with magnetic seed filtration, it can separate finer polymer microplastic particles from a diluted suspension with relatively high efficiency; membrane separation can remove micro / nano plastics in wastewater, and microplastics in sewage can be effectively removed by interception. However, it is still challenging to efficiently remove / separate microplastics because of their small volume and low concentration in polluted water. Moreover, most of these methods mainly rely on chemical flocculation and filtration, with high costs, and it is difficult to recycle and regenerate the fouled fillers and membranes, resulting in excessive energy consumption for long-term operation and maintenance.

[0004] In addition, there are also biological and chemical methods, such as photocatalysis, chemical digestion, microbial decomposition, etc. Biological removal methods are environmentally friendly, but the removal of microplastics is slow. Chemical removal methods are relatively expensive and may cause secondary pollution. Summary of the Invention

[0005] Details of one or more embodiments of the present invention are set forth in the following drawings and description to make other features, objects, and advantages of the present application more concise and understandable.

[0006] The present invention provides a water purification device and method for removing microplastics, which solves at least one of the above technical problems existing in the existing microplastic removal methods, realizes the efficient removal of microplastics in water without the need for additional chemical agents, and has the characteristics of renewable utilization.

[0007] On the one hand, the present invention discloses a water purification device for removing microplastics from water, which includes an electrochemically adsorbing and oxidizing unit and a self-cleaning desorbing unit.

[0008] The electrochemically adsorbing and oxidizing unit includes: a cylinder body, a cathode, a filter screen, an anode, three-dimensional particle electrodes, and a supporting layer for supporting the three-dimensional particle electrodes; a sewage inlet for sewage containing microplastics to enter the electrochemically adsorbing and oxidizing unit is opened at the bottom of the side surface of the cylinder body; the cathode is sleeved inside the cylinder body, is a cylindrical stainless steel mesh electrode, and is spaced from the inner wall of the bottom of the cylinder body at the bottom; the filter screen is sleeved inside the cathode and is connected to the inner wall of the bottom of the cylinder body at the bottom; the anode is located in the middle of the cylinder body; the three-dimensional particle electrodes are arranged between the filter screen and the anode; the bottom of the supporting layer is provided with openings with a diameter smaller than the diameter of the three-dimensional particle electrodes.

[0009] The self-cleaning desorbing unit is arranged at the top inside the cylinder body and includes a desorbing shell and a water outlet pipe; the desorbing shell is in an inverted conical shape and rotates driven by a driving member, the top is open to enable the three-dimensional particle electrodes to enter the shell for centrifugation, and the bottom is open to enable the desorbed three-dimensional particle electrodes to return to the electrochemically adsorbing and oxidizing unit; the water outlet pipe is arranged inside the shell and coincides with the central axis of the shell, and the bottom is open to discharge the desorbed microplastics.

[0010] In some embodiments, the top of the cylinder body is open to enable the water from which microplastics have been removed to flow out of the cylinder body; a flushing water inlet for flushing the three-dimensional particle electrodes adsorbed with microplastics from the electrochemically adsorbing and oxidizing unit into the desorbing shell is opened at the bottom of the cylinder body; the bottom of the anode is flush with the bottom of the cathode, and the bottom of the supporting layer is flush with the bottom of the cathode.

[0011] In some embodiments, a sludge channel is defined between the outer side surface of the filter screen and the inner wall of the cylinder body, and a sludge discharge port communicating with the sludge channel is opened at the bottom of the side surface of the cylinder body.

[0012] In some embodiments, the supporting layer includes a first supporting layer at the bottom, and a plurality of second supporting layers which are spaced from the first supporting layer and are located above the first supporting layer and are spaced from each other; the first supporting layer is provided with openings with a diameter smaller than the diameter of the three-dimensional particle electrodes, and the second supporting layers are provided with openings with a diameter larger than the diameter of the three-dimensional particle electrodes.

[0013] In some of these embodiments, the distance between the second supporting layer and the first supporting layer, and the distances between the second supporting layers are greater than the diameter of the three-dimensional particle electrode and less than twice the diameter of the three-dimensional particle electrode.

[0014] In some of these embodiments, the distance between the cathode and the anode is 10 - 20 cm; the material of the cathode is ruthenium, iridium, or aluminum; the anode is a titanium filter element electrode with a pore diameter of 0.1 - 1 mm; the three-dimensional particle electrode is a particle three-dimensional electrode made by oxidizing carbon black coupled with iron.

[0015] In some of these embodiments, the anode is a titanium filter element electrode oxidized in a muffle furnace at 350°C; the three-dimensional particle electrode is a particle electrode obtained by coupling carbon black, phenolic resin, and iron powder and oxidizing at 200°C. In the three-dimensional particle electrode, the proportion of carbon black is 90 - 98%, the proportion of phenolic resin is 1 - 5%, the proportion of iron powder is 1 - 5%, and the particle size of the three-dimensional particle electrode is 1 - 5 mm.

[0016] In some of these embodiments, the self-cleaning desorption unit further includes a guiding cover corresponding to the bottom opening of the desorption housing, and the guiding cover is conical.

[0017] In some of these embodiments, the self-cleaning desorption unit is connected to the anode; the desorption housing is made of stainless steel and is internally provided with a swirl corridor with an inner diameter of 5 - 15 mm; the inner diameter of the water outlet pipe is 0.5 - 4.5 mm.

[0018] On the other hand, the present invention discloses a method for removing microplastics from water by the water purification device for removing microplastics according to any one of the above technical solutions, including the following steps:

[0019] The water to be treated flows into the cathode from the sewage inlet. The cathode produces alkali under the action of electrolyzing water. The calcium and magnesium ions contained in the raw water combine with the alkali generated by the cathode to precipitate. After pretreatment by the cathode, large particle suspended substances are separated by a filter screen. The water filtered by the filter screen is introduced into the three-dimensional particle electrode. The microplastic particles in the water are adsorbed on the three-dimensional particle electrode by the positive and negative charges induced by the three-dimensional particle electrode, and advanced oxidation occurs on the surface of the three-dimensional particle electrode to achieve the degradation of microplastics. After being treated by the three-dimensional particle electrode, they gather near the anode. Through the further filtration and oxidation of the anode, the treated water flows out through the water outlet in the anode filter element.

[0020] When microplastics and other impurities increase on the three-dimensional particle electrode, blocking the water flow and generating turbulent flow that disturbs and floats up the three-dimensional particle electrode, the electrochemistry adsorption and oxidation unit is turned off and the self-cleaning desorption unit is turned on. The three-dimensional particle electrode is washed to the top by the action of the flushing water and enters the desorption housing. The three-dimensional particle electrode undergoes a centrifugal flow in the desorption housing, and the microplastics and impurities on the three-dimensional particle electrode are thrown out by the centrifugal action and discharged through the water outlet pipe with the water flow. The three-dimensional particle electrode returns to the support layer from the bottom opening of the desorption housing to complete self-cleaning.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention provides a water purification device for removing microplastics. Through the electro-adsorption and in-situ advanced oxidation of the induced three-dimensional particles of iron-coupled carbon black sandwiched between the cathode and anode, combined with the efficient removal of microplastics in the water body by the deep filtration and oxidation of the titanium filter element anode, and in cooperation with the self-cleaning system, the microplastics adsorbed by the used three-dimensional particles are desorbed by the combined action of water washing and floating and swirling centrifugation, realizing the regeneration of the three-dimensional particles. Without the need for additional chemical agents, the efficient removal of microplastics in the water body is achieved, and at the same time, the material can be recycled and reused. Description of the Drawings

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 is a schematic structural diagram of the water purification device for removing microplastics provided by the embodiment of the present invention;

[0025] Figure 2 is a schematic structural diagram of the self-cleaning desorption unit provided by the embodiment of the present invention;

[0026] Description of the Drawings: 101, cylinder; 102, cathode; 103, filter screen; 104, anode; 105, three-dimensional particle electrode; 1061, first support layer; 1062, second support layer; 201, desorption housing; 202, water outlet pipe; 203, export cover; 301, sewage inlet; 302, flushing water inlet; 303, sludge discharge port. Detailed Embodiments

[0027] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described and explained below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0028] Obviously, the accompanying drawings in the following description are only some examples or embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, the present invention can also be applied to other similar scenarios based on these drawings. In addition, it can also be understood that although the efforts made in such a development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present invention, some design, manufacturing, or production changes based on the technical content disclosed in the present invention are only conventional technical means and should not be understood as the content disclosed in the present invention being insufficient.

[0029] The mention of "embodiment" in the present invention means that the specific features, structures, or characteristics described in connection with the embodiment can be included in at least one embodiment of the present invention. The appearance of this phrase at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those of ordinary skill in the art explicitly and implicitly understand that the embodiments described in the present invention can be combined with other embodiments without conflict.

[0030] Unless otherwise defined, the technical terms or scientific terms involved in the present invention should have the ordinary meaning understood by those of ordinary skill in the technical field to which the present invention belongs. The words such as "a", "an", "one", "the" and the like involved in the present invention do not indicate a limitation in quantity and can represent a singular or plural number. The terms "comprising", "including", "having" and any variations thereof involved in the present invention are intended to cover non-exclusive inclusion; for example, a process, method, system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or units, but may further include unlisted steps or units, or may further include other steps or units inherent to these processes, methods, products or devices. The terms "connected", "coupled" and the like involved in the present invention are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "plurality" involved in the present invention refers to two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, "A and / or B" may represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after. The terms "first", "second" and the like involved in the present invention are only used to distinguish similar objects and do not represent a specific order for the objects.

[0031] An embodiment of the present invention provides a water purification device for removing microplastics. Figure 1 It is a schematic structural diagram of a water purification device for removing microplastics according to an embodiment of the present invention. Refer toFigure 1 As shown, the water purification device for removing microplastics is used for removing microplastics in water, and at least includes: an electrochemically adsorptive oxidation unit and a self-cleaning desorption unit;

[0032] The electrochemically adsorptive oxidation unit includes: a cylinder 101, a cathode 102, a filter screen 103, an anode 104, a three-dimensional granular electrode 105, and a supporting layer for supporting the three-dimensional granular electrode 105; a sewage inlet 301 for sewage containing microplastics to enter the electrochemically adsorptive oxidation unit is opened at the bottom of the side surface of the cylinder 101; the cathode 102 is sleeved inside the cylinder 101 and is a cylindrical stainless steel mesh electrode, and the bottom is spaced from the inner wall of the bottom of the cylinder 101; the filter screen 103 is sleeved inside the cathode 102, and the bottom is connected to the inner wall of the bottom of the cylinder 101; the anode 104 is located in the middle of the cylinder 101; the three-dimensional granular electrode 105 is arranged between the filter screen 103 and the anode 104; the bottom of the supporting layer is provided with an opening with a diameter smaller than that of the three-dimensional granular electrode 105;

[0033] As Figure 2 shown, the self-cleaning desorption unit is arranged at the top inside the cylinder 101 and includes a desorption housing 201 and a water outlet pipe 202; the desorption housing 201 is inverted conical and rotates driven by a driving member, the top is open to enable the three-dimensional granular electrode 105 to enter the housing for centrifugation, and the bottom is open to enable the desorbed three-dimensional granular electrode 105 to return to the electrochemically adsorptive oxidation unit; the water outlet pipe 202 is arranged inside the housing and coincides with the central axis of the housing, and the bottom is open to discharge the desorbed microplastics.

[0034] The above electrochemically adsorptive oxidation unit adopts a structure of a cylindrical double-cylinder electrode coupled with an internal three-dimensional granular electrode 105, with the outer cathode 102 and the inner anode 104; the raw water intercepts large particle plastic impurities such as calcium and magnesium through the in-situ alkali production of the cathode 102 and the interception of the filter screen 103, and the intercepted impurities are discharged through the sludge outlet 303; the raw water entering the three-dimensional granular electrode 105 through radial flow generates positive and negative charges on the particle surface due to the electroinductive system of the anode and cathode 104, and the positive and negative charges adsorb the microplastics with positive or negative charges; the three-dimensional granular electrode 105 is made of carbon black with a rough surface and a large porosity, which strengthens the adsorption of microplastics. Iron in the three-dimensional electrode will generate hydroxyl radicals under the action of electrochemistry, and then gradually degrade and remove the adsorbed microplastics through advanced oxidation. Further, by limiting the diameter of the three-dimensional granular electrode 105, the filtration and removal of microplastics with corresponding particle sizes can be effectively achieved; a larger contact area can be obtained by entering the three-dimensional electrode particles through radial flow, improving the removal effect of microplastics; the above three-dimensional granular electrode 105 is separated by a supporting layer, effectively preventing particle dispersion.

[0035] After long-term operation, the system is backwashed. By reversing the connection of the electrodes, the desorption of microplastics is realized, and the bottom backwashing water is used for flushing. The granular electrodes are separated from the microplastics through the self-cleaning desorption unit above, realizing the regeneration of the granules. Specifically, the self-cleaning desorption unit is controlled to start according to the arrangement of the three-dimensional granular electrodes 105 on the supporting layer. When the microplastics and other impurities on the three-dimensional granular electrodes 105 increase and block the water flow, generating a turbulent flow that disturbs and floats up the three-dimensional granular electrodes 105, the water inlet is closed and the self-cleaning desorption is started. After the self-cleaning desorption unit is started, the backwashing water enters from the bottom backwashing water inlet 302, and the water volume is evenly distributed through the bottom supporting layer, achieving a uniform backwashing effect without dead angles. Under the action of the backwashing water flow, the three-dimensional granular electrodes 105 are separated from the supporting layer and flushed to the top and enter the cyclone desorption device. Under the action of the cyclone rotation, the microplastics and impurities on the surface of the three-dimensional granules are separated through centrifugal force and mutual friction. The three-dimensional granules are discharged from the bottom of the cyclone desorption device due to their heavier weight, while the desorbed microplastics and impurities are discharged through the water outlet pipe 202 along the waste water outlet through centrifugal force, realizing the self-cleaning of the three-dimensional granules; when the three-dimensional granules evenly cover the supporting layer and the water inlet no longer generates turbulence, the self-cleaning desorption system is stopped.

[0036] The above-mentioned water purification device for removing microplastics uses the electro-adsorption and in-situ advanced oxidation of the induced three-dimensional particles of iron-coupled carbon black sandwiched between the anode and cathode 104, combines the deep filtration and oxidation of the titanium filter element anode 104 to efficiently remove microplastics in the water body, and cooperates with the self-cleaning system. Through the coupling of water washing and floating and cyclone centrifugation, the microplastics adsorbed by the used three-dimensional particles are desorbed, realizing the regeneration of the three-dimensional particles. Without the need for additional chemical agents, the efficient removal of microplastics in the water body is achieved, and at the same time, the materials can be recycled. The above device of the present invention is used to treat sewage with very small volume and very low concentration of microplastics, and realizes the efficient removal of microplastics through the coupling of filtration and adsorption and advanced oxidation; this process does not require the addition of additional agents, and the removal operation cost is low; the microplastics in the water body carry positive / negative charges, and the removal efficiency of microplastics is greatly enhanced through the adsorption filtration and synchronous advanced oxidation of the induced electric field; the three-dimensional particle induced electric field and surface adsorption performance are used to accelerate the removal of microplastics; through the cyclone backwashing effect, the regeneration function of the system is realized; at the same time, the large particle microplastic waste is discharged through the bottom sludge discharge.

[0037] In some of these embodiments, the top of the cylinder body 101 is open to allow the water from which microplastics have been removed to flow out of the cylinder body 101; a flushing water inlet 302 is provided at the bottom of the cylinder body 101 for flushing the three-dimensional particle electrode 105 adsorbed with microplastics from the electrochemically adsorptive oxidation unit into the desorption housing 201; the bottom of the anode 104 is flush with the bottom of the cathode 102, and the bottom of the supporting layer is flush with the bottom of the cathode 102. By providing the flushing water inlet 302 at the bottom of the cylinder body 101 and defining that the bottom of the supporting layer is flush with the bottom of the cathode 102, a space is formed between the supporting layer and the inner wall of the cylinder body 101, which is conducive to fully utilizing the openings provided on the supporting layer to achieve uniform water distribution and achieve a uniform backwashing effect without dead corners.

[0038] In some of these embodiments, the outer side of the filter screen 103 and the inner wall of the cylinder body 101 define a sludge channel, and a sludge discharge port 303 communicating with the sludge channel is provided at the bottom of the side of the cylinder body 101. The large particle impurities containing microplastics generated in the pretreatment stage in the electrochemically adsorptive oxidation unit are discharged through the sludge discharge port 303.

[0039] In some of these embodiments, the supporting layer includes a first supporting layer 1061 at the bottom, and a plurality of second supporting layers 1062 which are spaced from the first supporting layer 1061 and are located above the first supporting layer 1061 and are spaced from each other; the first supporting layer 1061 is provided with openings having a diameter smaller than the diameter of the three-dimensional particle electrode 105, and the second supporting layers 1062 are provided with openings having a diameter larger than the diameter of the three-dimensional particle electrode 105. The supporting layer adopts a multi-layer structure. Compared with a single-layer structure, this structural form is more conducive to the uniform distribution of the three-dimensional particle electrode 105. At the same time, when the three-dimensional particle electrode 105 has a large adsorption capacity, the second supporting layer 1062 can be used to fix the three-dimensional particle electrode 105 to prevent the three-dimensional particle electrode 105 from dispersing. Further, when the microplastics and other impurities on the three-dimensional particle electrode 105 increase and block the water flow, generating a turbulent flow that causes the three-dimensional particle electrode 105 to be disturbed and float, it can also be used as a timing for judging the desorption of the three-dimensional particle electrode 105. Further, the distance between the second supporting layer 1062 and the first supporting layer 1061, and the distance between each second supporting layer 1062 are greater than the diameter of the three-dimensional particle electrode 105 and less than twice the diameter of the three-dimensional particle electrode 105.

[0040] In some of these embodiments, the distance between the cathode 102 and the anode 104 is 10 - 20 cm; the material of the cathode 102 is ruthenium, iridium, or aluminum; the anode 104 is a titanium filter element electrode with a pore diameter of 0.1 - 1 mm; the three-dimensional particle electrode 105 is a particle three-dimensional electrode made by oxidizing carbon black coupled with iron. Further, the pore size of the titanium filter element is 0.03 - 0.08 mm. The current density during electrolysis can be 1 - 10 mA / cm2. It can be understood that the distance between the cathode 102 and the anode 104 can also be 12 cm, 14 cm, 16 cm, 18 cm, and any point value within this range, and the pore diameter of the anode 104 can also be 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, and any point value within this range.

[0041] In some of these embodiments, the anode 104 is a titanium filter element electrode oxidized in a muffle furnace at 350°C; the three-dimensional particle electrode 105 is a particle electrode obtained by coupling carbon black, phenolic resin, and iron powder and oxidizing at 200°C. In the three-dimensional particle electrode 105, the proportion of carbon black is 90 - 98%, the proportion of phenolic resin is 1 - 5%, and the proportion of iron powder is 1 - 5%. The particle size of the three-dimensional particle electrode 105 is 1 - 5 mm. The particle size of the three-dimensional particle electrode 105 can also be 2 mm, 3 mm, 4 mm, and any point value within this range. Among them, the phenolic resin used in the three-dimensional particle electrode 105 acts as a binder for the combination of carbon black and iron powder before oxidation. After oxidation, the phenolic resin is consumed, increasing the specific surface area of the three-dimensional particles and improving the removal effect of microplastics. The carbon black in the particles of the three-dimensional particle electrode 105 has strong adsorption, which can further improve the adsorption performance. Through the action of the induced electric field, iron in the particles of the three-dimensional particle electrode 105 undergoes advanced oxidation to generate hydrogen peroxide and hydroxyl radicals for in-situ oxidation of microplastics, further achieving degradation. The three-dimensional particle electrode 105 is supported by a bottom support layer, and the support layer arranges the three-dimensional particle electrode 105 evenly.

[0042] In some of these embodiments, the self-cleaning desorption unit further includes a guide cover 203 corresponding to the bottom opening of the desorption housing 201, and the guide cover 203 is conical. The setting of the guide cover 203 is beneficial, on the one hand, to the export of the three-dimensional particle electrode 105 that is concentrated near the inner wall of the desorption housing 201 due to greater gravity during centrifugation, and on the other hand, this structural form is also beneficial for the flushing water to drive the three-dimensional particle electrode 105 to be desorbed into the desorption housing 201 through the top opening of the desorption housing 201 for centrifugal desorption, ensuring the separation of various material channels and avoiding the effect impact caused by mixing.

[0043] In some of these embodiments, the self-cleaning desorption unit is connected to the anode 104; the desorption housing 201 is made of stainless steel and is internally provided with a swirl corridor with an inner diameter of 5-15 mm, which plays a role in centrifugal separation and is integrally cast on top of the anode 104; the inner diameter of the water outlet pipe 202 is 0.5-4.5 mm. It can be understood that the inner diameter of the corridor can also be 7 mm, 9 mm, 11 mm, 13 mm, and any point value within this range, and the inner diameter of the water outlet pipe 202 can also be 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, and any point value within this range.

[0044] On the other hand, the present invention discloses a method for removing microplastics from the water purification device for removing microplastics of any of the above technical solutions, including the following steps:

[0045] The water to be treated flows into the cathode 102 from the sewage inlet 301. The cathode 102 produces alkali under the action of electrolyzing water. The calcium and magnesium ions contained in the raw water combine with the alkali generated by the cathode 102 to precipitate. After being pretreated by the cathode 102, large particulate suspended substances are separated by the filter screen 103. The water filtered by the filter screen 103 is introduced into the three-dimensional particle electrode 105. The microplastic particles in the water are adsorbed on the three-dimensional particle electrode 105 by the positive and negative charges induced by the three-dimensional particle electrode 105, and advanced oxidation occurs on the surface of the three-dimensional particle electrode 105 to achieve the degradation of microplastics. After being treated by the three-dimensional particle electrode 105, they gather near the anode 104. Through the further filtering and oxidation action of the anode 104, the treated water flows out of the anode 104 filter element through the water outlet.

[0046] When the microplastics and other impurities on the three-dimensional particle electrode 105 increase and block the water flow, generating a turbulent flow that disturbs and floats the three-dimensional particle electrode 105, the electrochemically adsorbed oxidation unit is turned off and the self-cleaning desorption unit is turned on. The three-dimensional particle electrode 105 is washed to the top under the action of the flushing water and enters the desorption housing 201. The three-dimensional particle electrode 105 undergoes a centrifugal flow effect in the desorption housing 201. The microplastics and impurities on the three-dimensional particle electrode 105 are centrifugally thrown out and discharged through the water outlet pipe 202 along with the water flow. The three-dimensional particle electrode 105 returns to the support layer through the bottom opening of the desorption housing 201 to complete self-cleaning.

[0047] The advantages of the adsorption-coupled electrochemical process include environmental compatibility, low capital cost, energy efficiency, sludge minimization, ease of automation, and cost-effectiveness. Coupled with the simple and inexpensive characteristics of physical removal methods, the use of chemical reagents is avoided in the water treatment process, and rapid online separation of pollutants is achieved at a lower cost and lower energy consumption. The backwashing system utilizes the swirling effect to achieve efficient system regeneration without the addition of chemical agents. The above process uses a physical isolation and electrochemical adsorption-coupled advanced oxidation system to remove microplastics in water without the addition of additional chemicals, and can achieve stable long-term operation through its own efficient backwashing device.

[0048] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0049] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A water purification device for removing microplastics, characterized in that, For the removal of microplastics in water, it includes an electrochemically adsorptive oxidation unit and a self-cleaning desorption unit; The electrochemically adsorptive oxidation unit includes: A cylinder body, at the bottom of the side of which there is a sewage inlet for sewage containing microplastics to enter the electrochemically adsorptive oxidation unit; A cathode, which is sleeved inside the cylinder body, is a cylindrical stainless steel mesh electrode, and is spaced from the inner wall of the bottom of the cylinder body at the bottom; A filter screen, which is sleeved inside the cathode and is connected to the inner wall of the bottom of the cylinder body at the bottom; An anode, which is located in the middle of the cylinder body; Three-dimensional granular electrodes, which are arranged between the filter screen and the anode; A supporting layer for supporting the three-dimensional granular electrodes, and the bottom of the supporting layer is provided with openings with apertures smaller than the diameter of the three-dimensional granular electrodes; the supporting layer includes a first supporting layer at the bottom, and a plurality of second supporting layers that are spaced from the first supporting layer and are located above the first supporting layer and are spaced from each other; the first supporting layer is provided with openings with apertures smaller than the diameter of the three-dimensional granular electrodes, and the second supporting layers are provided with openings with apertures larger than the diameter of the three-dimensional granular electrodes; The distance between the cathode and the anode is 10 - 20 cm; the material of the cathode is ruthenium, iridium, or aluminum; the anode is a titanium filter element electrode with an aperture of 0.1 - 1 mm; the three-dimensional granular electrodes are granular three-dimensional electrodes made by oxidizing carbon black coupled with iron; The anode is a titanium filter element electrode oxidized in a muffle furnace at 350 °C; the three-dimensional granular electrodes are granular electrodes obtained by coupling carbon black, phenolic resin, and iron powder and oxidizing at 200 °C, in the three-dimensional granular electrodes, the carbon black accounts for 90 - 98%, the phenolic resin accounts for 1 - 5%, the iron powder accounts for 1 - 5%, and the particle size of the three-dimensional granular electrodes is 1 - 5 mm; The self-cleaning desorption unit is arranged at the top inside the cylinder body and includes: A desorption housing, which is in an inverted conical shape and rotates driven by a driving member, with an opening at the top to allow the three-dimensional granular electrodes to enter the housing for centrifugation, and an opening at the bottom to allow the desorbed three-dimensional granular electrodes to return to the electrochemically adsorptive oxidation unit; An outlet pipe, which is arranged inside the housing and coincides with the central axis of the housing, with an opening at the bottom to discharge the desorbed microplastics; The distance between the second supporting layer and the first supporting layer, and the distance between each of the second supporting layers is greater than the diameter of the three-dimensional granular electrodes and less than twice the diameter of the three-dimensional granular electrodes.

2. The water purification device for removing microplastics according to claim 1, wherein The top of the cylinder body is open to allow the water with removed microplastics to flow out of the cylinder body; the bottom of the cylinder body is provided with a flushing water inlet for flushing the three-dimensional granular electrodes adsorbed with microplastics from the electrochemically adsorptive oxidation unit into the desorption housing; the bottom of the anode is flush with the bottom of the cathode, and the bottom of the supporting layer is flush with the bottom of the cathode.

3. The water purification device for removing microplastics according to claim 2, wherein, The outer side of the filter screen and the inner wall of the cylinder body define a sludge channel, and the side bottom of the cylinder body is provided with a sludge discharge port communicating with the sludge channel.

4. The water purification device for removing microplastics according to claim 1, wherein, The self-cleaning desorption unit further includes a guiding cover corresponding to the bottom opening of the desorption housing, and the guiding cover is conical.

5. The water purification device for removing microplastics according to claim 4, wherein The self-cleaning desorption unit is connected to the anode; the desorption housing is made of stainless steel and is internally provided with a swirling corridor, and the inner diameter of the corridor is 5-15 mm; the inner diameter of the water outlet pipe is 0.5-4.5 mm.

6. A method for removing microplastics in water by using the water purification device for removing microplastics according to any one of claims 1-5, characterized in that, It includes the following steps: The water to be treated flows into the cathode from the sewage inlet. The cathode produces alkali under the action of electrolyzing water. The calcium and magnesium ions contained in the raw water combine with the alkali generated by the cathode to precipitate. After being pretreated by the cathode, large particulate suspended matter is separated by a filter screen. The water filtered by the filter screen is introduced into the three-dimensional particle electrode. The microplastic particles in the water are adsorbed on the three-dimensional particle electrode by the positive and negative charges induced by the three-dimensional particle electrode, and advanced oxidation occurs on the surface of the three-dimensional particle electrode to achieve the degradation of microplastics. After being treated by the three-dimensional particle electrode, it aggregates near the anode. Through the further filtration and oxidation of the anode, the treated water flows out through the water outlet in the anode filter element. When the microplastics and other impurities on the three-dimensional particle electrode increase and block the water flow, a turbulent flow is generated to disturb and float the three-dimensional particle electrode. The electrochemistry adsorption and oxidation unit is turned off and the self-cleaning desorption unit is turned on. The three-dimensional particle electrode is washed to the top under the action of the flushing water and enters the desorption housing. The three-dimensional particle electrode undergoes a centrifugal flow in the desorption housing. The microplastics and impurities on the three-dimensional particle electrode are thrown out by the centrifugal force and discharged through the water outlet pipe along with the water flow. The three-dimensional particle electrode returns to the supporting layer from the bottom opening of the desorption housing to complete self-cleaning.

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