An atmospheric microplastic deposition sampler

Abstract

This utility model relates to the field of environmental monitoring technology and discloses an atmospheric microplastic sedimentation sampler, including a sedimentation cylinder connected to a support, with an opening at the bottom of the sedimentation cylinder. It also includes a storage tank, a filter assembly, and a collection bottle. The storage tank is rotatably connected to one side of the support and is used to fill with cleaning fluid. As the storage tank rotates upwards to above the sedimentation cylinder, its outlet aligns with the sedimentation cylinder. The filter assembly includes a collar detachably connected to the lower opening of the sedimentation cylinder and a screen disposed within the collar for screening impurities. The collection bottle is detachably connected below the collar for collecting the sieved mixture. This utility model facilitates the effective and continuous collection and transportation of microplastics.

Description

Technical Field

[0001] This utility model relates to the field of environmental monitoring technology, and in particular to an atmospheric microplastic deposition sampler. Background Technology

[0002] Atmospheric microplastics, as a new type of pollutant, are widely distributed in the air we breathe through suspension, transport, deposition, and resuspension. Possible sources include plastic waste incineration, industrial emissions from automobile tire production, textiles and clothing, agricultural mulch film and fertilizer use, people's daily activities, as well as mechanical wear and weathering of larger plastics. The chemical toxicity and extremely long half-life of microplastics themselves pose a long-term exposure risk to humans and other organisms. Therefore, it is necessary to monitor atmospheric microplastics. Atmospheric microplastic deposition samplers are usually used to collect air samples from a wide range of sampling points.

[0003] Common sedimentation samplers typically consist of a sedimentation tank with an open top and a support for holding the tank. Specifically, to ensure structural stability and suitability for harsh outdoor environments, both the sedimentation tank and the support are usually made of metal. Atmospheric microplastics gradually settle into the sedimentation tank due to gravity, downdrafts, or attachment to leaves, dust particles, and other impurities, and are collected. After a predetermined collection time, the sedimentation tank containing the microplastics and impurities is sealed and transported to a laboratory. Hydrogen peroxide is used to flush away the collected impurities and leaves, filtering out the microplastics and dissolving some of the impurities. The water containing the microplastics is then tested and analyzed.

[0004] However, the sedimentation tanks currently used for sampling are generally large and heavy, which makes them inconvenient to carry, transport, disassemble, and rinse. After being transported, the sedimentation tanks are also difficult to use for continuous sampling. Furthermore, as the samples are transported for a long time, there is a risk of secondary contamination or sample loss. Utility Model Content

[0005] This invention provides an atmospheric microplastic deposition sampler, which facilitates the effective and continuous collection and transportation of microplastics.

[0006] This utility model provides an atmospheric microplastic sedimentation sampler, including a sedimentation cylinder connected to a support, with an opening at the bottom of the sedimentation cylinder, and further including: a storage tank, a filter assembly, and a collection bottle. The storage tank is rotatably connected to one side of the support, and a turning rod is fixedly connected to the side wall of the storage tank. The other end of the turning rod is rotatably connected to the support through a hinge frame. The storage tank is used to fill cleaning fluid. As the storage tank rotates upward to above the sedimentation cylinder, its outlet is aligned with the sedimentation cylinder. The filter assembly includes a collar detachably connected to the lower opening of the sedimentation cylinder and a screen set inside the collar for screening impurities. The collection bottle is detachably connected to the lower part of the collar for collecting the sieved mixture.

[0007] Preferably, the settling cylinder has a cylindrical body, and the part near the lower opening has a tapered constriction shape, with the size of the collar matching the size of the lower opening of the settling cylinder.

[0008] Preferably, the lower opening of the settling cylinder and the opening of the collection bottle are both provided with external threads, and the inner walls of the collar located above and below the screen are both provided with internal threads that are respectively threaded to the settling cylinder and the collection bottle.

[0009] Preferably, the outlet end of the liquid storage tank is detachably connected to an end cap, and the end cap is evenly provided with a number of spray holes along its thickness direction to spray the cleaning liquid inside. A piston is inserted inside the liquid storage tank, and a counterweight is fixedly connected to the end of the piston away from the outlet. When the liquid storage tank rotates upward to above the settling cylinder, the counterweight uses gravity to spray the cleaning liquid out through the spray holes.

[0010] Preferably, the end of the reservoir away from the outlet is detachably connected to a retaining ring to prevent the piston from falling off.

[0011] Preferably, the support includes: a base, a telescopic rod, and a placement frame. The base is provided with anchor bolts for connecting to the ground. The telescopic rod is vertically fixed to the upper part of the base. The placement frame includes an upper ring and a lower ring, both fixed to the top of the output end of the telescopic rod. The upper ring is located above the lower ring. The inner ring size of the upper ring is larger than the outer diameter of the settling cylinder. The inner ring size of the upper ring is larger than the inner ring size of the lower ring. It is used for the longitudinal placement of the settling cylinder. The hinge frame is fixedly connected to the side wall of the upper or lower ring.

[0012] Preferably, both the upper and lower rings are fixedly connected to the output end of the telescopic rod via a truss.

[0013] Preferably, the cleaning solution used to fill the storage tank is a hydrogen peroxide solution.

[0014] Preferably, the screen aperture size is 4mm to 5mm.

[0015] Preferably, the upper end of the settling cylinder is equipped with a cover for sealing, which can be used for subsequent classification and collection of dry and wet microplastics.

[0016] Preferably, each nozzle on the outermost ring of the end cap is connected to a hollow conduit that guides the cleaning fluid toward the inner wall of the settling tank. This allows the cleaning fluid to not only wash away microplastics carried in the leaves or impurities, but also clean the microplastics and dust adhering to the inner wall of the settling tank. This not only greatly improves the collection efficiency of microplastics, but also cleans the inner wall of the settling tank, thereby improving the efficiency of continuous collection and avoiding troublesome cleaning.

[0017] Compared to existing technologies, this sampler achieves effective and rapid collection of microplastics without disassembling the settling tank. It also allows for quick transition to the next sampling round and eliminates the risk of secondary contamination or loss of microplastics during transportation. Specifically, this sampler uses cleaning fluid from a storage tank at the collection site to directly clean the microplastic-containing impurities collected in the settling tank. With filtration by the filter assembly, the numerous microplastics are effectively and rapidly collected directly in a collection bottle as a mixture. Compared to transporting impurities and the settling tank, this not only reduces transportation difficulty but also effectively improves the overall efficiency of microplastic collection. The sampler boasts high efficiency and features a detachable connection between the collection bottle and the collar, making the sampling process extremely convenient. The collection bottle is sealed with a cap, reducing transportation difficulties. Compared to a sedimentation tank, this collection bottle is less expensive, allowing for multiple bottles to be kept on hand without complicated disassembly. Once a certain amount has been collected, it can be quickly disassembled and an empty collection bottle installed, enabling continuous or sustainable collection of microplastics. Finally, this sampler not only effectively collects microplastics but also performs preliminary cleaning and coarse filtration, saving time for subsequent testing and significantly improving overall testing efficiency.

[0018] Specifically, by opening the bottom of the settling tank, larger or smaller impurities carrying microplastics can be collected into it. The storage tank allows for on-site cleaning of the impurities in the settling tank by rotating the tank, thereby flushing away as much of the microplastics adhering to the impurities as possible into the collection bottle. The included filter component prevents excessive amounts of larger impurities from remaining in the collection bottle. The collection bottle enables direct collection of the test mixture and is easier to transport and carry than the settling tank. Attached Figure Description

[0019] Figure 1 A schematic cross-sectional view of the front part of an atmospheric microplastic deposition sampler in state one, provided as an embodiment of this utility model;

[0020] Figure 2 for Figure 1 A magnified view of part A in the middle;

[0021] Figure 3 A schematic diagram of the front structure of an atmospheric microplastic deposition sampler in state two, provided for an embodiment of this utility model;

[0022] Figure 4 A partial structural schematic diagram of an atmospheric microplastic deposition sampler provided for an embodiment of this utility model;

[0023] Figure 5 A schematic diagram of the structure of a filter component in an atmospheric microplastic deposition sampler provided in this embodiment of the present invention;

[0024] Figure 6 A schematic diagram of the top-view structure of the screen in an atmospheric microplastic deposition sampler provided for an embodiment of this utility model;

[0025] Figure 7 A schematic diagram of the structure of the end cap of an atmospheric microplastic sedimentation sampler provided in this embodiment of the present invention;

[0026] Figure 8 A schematic diagram of the support structure in an atmospheric microplastic sedimentation sampler provided for an embodiment of this utility model;

[0027] Figure 9 This is a partial structural diagram of the support frame in an atmospheric microplastic sedimentation sampler provided for an embodiment of this utility model.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Support; 11. Base; 12. Telescopic rod; 131. Upper ring sleeve; 132. Lower ring sleeve; 2. Settling cylinder; 3. Storage tank; 31. Outlet; 32. End cap; 321. Spray nozzle; 33. Piston; 34. Counterweight; 35. Guide tube; 4. Cleaning fluid; 5. Filter assembly; 51. Collar; 52. Screen; 6. Collection bottle; 7. Turning rod; 8. Hinge frame. Detailed Implementation

[0030] The following describes a specific embodiment of the present invention in detail with reference to the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0031] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0032] refer to Figure 1 , Figure 3 and Figure 4 This utility model provides an atmospheric microplastic sedimentation sampler, including a sedimentation cylinder 2 connected to a support 1, with an opening at the bottom of the sedimentation cylinder 2, and further including: a storage tank 3, a filter assembly 5, and a collection bottle 6. The storage tank 3 is rotatably connected to one side of the support 1, and a turning rod 7 is fixedly connected to the side wall of the storage tank 3. The other end of the turning rod 7 is rotatably connected to the support 1 through a hinge frame 8. The storage tank 3 is used to fill cleaning liquid 4. As the storage tank 3 rotates upward to above the sedimentation cylinder 2, its outlet 31 is aligned with the sedimentation cylinder 2. The filter assembly 5 includes a collar 51 detachably connected to the lower opening of the sedimentation cylinder 2 and a screen 52 disposed in the collar 51 for screening impurities. The collection bottle 6 is detachably connected to the lower part of the collar 51 for collecting the sieved mixture.

[0033] In the above embodiments, this sampler can effectively and quickly collect microplastics without disassembling the settling tank 2. It also allows for rapid transition to the next sampling round and eliminates the risk of secondary contamination or loss of microplastics during transportation. Specifically, the sampler uses the cleaning solution 4 in the storage tank 3 to directly clean the microplastic-containing impurities collected in the settling tank 2 at the collection site. With filtration by the filter assembly 5, the numerous microplastics are effectively and quickly collected directly in the collection bottle 6 as a mixed solution. Compared to transporting impurities and the settling tank 2, this not only reduces transportation difficulty but also effectively improves the overall efficiency of microplastic collection. The sampler is highly efficient, and the collection bottle 6 and the collar 51 are detachably connected, making the sampling process very convenient. By capping the collection bottle 6, a liquid seal is achieved, reducing transportation difficulties. Compared to the settling tank 2, the collection bottle 6 is less expensive, allowing for multiple bottles to be prepared without complicated disassembly and assembly. After a certain amount of microplastics has been collected, the bottle can be quickly disassembled and an empty collection bottle 6 installed, enabling continuous or sustainable collection of microplastics. Finally, this sampler not only effectively collects microplastics but also performs preliminary cleaning and coarse filtration, saving time for subsequent testing and significantly improving overall testing efficiency.

[0034] Specifically, by opening the bottom of the settling tank 2, larger or smaller impurities carrying microplastics can be collected into it. The storage tank 3 allows the cleaning solution 4 inside the tank to be directly cleaned by rotating the storage tank 3 at the collection site, thereby rinsing the microplastics attached to the impurities into the collection bottle 6 as much as possible. The filter component 5 prevents too many large impurities from being present in the collection bottle 6. The collection bottle 6 enables the direct collection of the test mixture and is easier to transport and carry than the settling tank 2.

[0035] The turning rod 7, in conjunction with the hinge frame 8, can provide the effect of rotating the liquid storage tank 3 above or to one side of the settling cylinder 2. Specifically, a limiting block is also provided to maintain the longitudinal extension when the liquid storage tank 3 is rotated upward or downward to the limit position. The limiting block is fixed on the support of the hinge frame 8 to avoid excessive rotation or tilting of the liquid storage tank 3.

[0036] Further, refer to Figure 3 The body of the settling cylinder 2 is cylindrical, and the part near the lower opening is tapered and narrowed. The size of the collar 51 matches the size of the lower opening of the settling cylinder 2.

[0037] In the above embodiments, the settling cylinder 2 is designed with a special structure, which can use the upper cylindrical structure to block larger branches and leaves and other impurities, making it difficult for them to continue falling from the constricted part, and also avoiding the effect of these larger impurities blocking the lower opening of the settling cylinder 2.

[0038] Further, refer to Figure 4 The lower opening of the settling cylinder 2 and the opening of the collection bottle 6 are both provided with external threads, and the inner walls of the collar 51 located above and below the screen 52 are provided with internal threads that are respectively threaded to the settling cylinder 2 and the collection bottle 6.

[0039] In the above embodiments, both the lower opening of the sedimentation cylinder 2 and the opening of the collection bottle 6 are provided with external threads, and the inner walls of the collar 51 located above and below the screen 52 are provided with internal threads that are respectively threaded to the sedimentation cylinder 2 and the collection bottle 6, which can achieve the effect of quick assembly and disassembly. Specifically, this device directly realizes the effect of independent transportation of the collected microplastic mixture by the collection bottle 6 through quick assembly and disassembly, making transportation more convenient and eliminating the tedious process of rinsing, filtering, and digesting insect organisms before the experiment. The digestion process of impurities or organisms can be realized directly during transportation, which greatly improves the efficiency of detection. Specifically, the collection bottle 6 is preferably a transparent glass bottle with a volume that can be viewed, and the volume is preferably 500ml. When wet sedimentation collection is required, an appropriate volume can be selected according to the actual situation, such as 1000ml and 1500ml.

[0040] Further, refer to Figure 2 and Figure 7 The storage tank 3 has a cylindrical structure with openings at both the top and bottom. The end cap 32 is detachably connected to the outlet 31 of the storage tank 3. The end cap 32 has several spray holes 321 evenly opened along its thickness direction to spray the cleaning liquid 4 inside. A piston 33 is inserted inside the storage tank 3. A counterweight 34 is fixedly connected to the end of the piston 33 away from the outlet 31. When the storage tank 3 rotates upward to the top of the settling tank 2, the counterweight 34 sprays the cleaning liquid 4 out through the spray holes 321 by gravity. Hollow conduits 35 are inserted and connected to each spray hole 321 on the outermost ring of the end cap 32 to guide the cleaning liquid 4 toward the inner wall of the settling tank 2.

[0041] In the above embodiments, the multiple conduits 35 allow the cleaning fluid 4 to not only rinse away microplastics carried in the leaves or impurities, but also clean the microplastics and dust adhering to the inner wall of the settling tank 2. This not only greatly improves the collection of microplastics, but also cleans the inner wall of the settling tank 2, thereby improving the efficiency of continuous collection and avoiding the troublesome cleaning process. With the pressure of the counterweight 34, the cleaning fluid 4 is squeezed and sprayed under pressure onto one side of the inner wall of the settling tank 2 through the conduits 35, avoiding the need to disassemble and clean the settling tank 2 after replacing the collection bottle 6. When there is stubborn mud or other debris, the staff only needs to clean it with a brush, and the filter assembly 5 can be removed during the operation.

[0042] Further, refer to Figure 2 The end of the storage tank 3 away from the outlet 31 is detachably connected to a retaining ring to prevent the piston 33 from falling off.

[0043] In the above embodiments, the risk of piston 33 falling out of the liquid storage tank 3 along with counterweight 34 after the liquid storage tank 3 is not in use and is rotated downwards can be prevented.

[0044] Further, refer to Figure 1 , Figure 3 and Figure 8 The bracket 1 includes: a base 11, a telescopic rod 12, and a placement frame. The base 11 is provided with anchor bolts for connecting to the ground. The telescopic rod 12 is vertically fixed to the upper part of the base 11. The placement frame includes an upper ring 131 and a lower ring 132, both fixed to the top of the output end of the telescopic rod 12. The upper ring 131 is located above the lower ring 132. The inner ring size of the upper ring 131 is larger than the outer diameter of the cylindrical part of the settling cylinder 2. The inner ring size of the upper ring 131 is larger than the inner ring size of the lower ring 132. It is used for the longitudinal placement of the settling cylinder 2. The hinge frame 8 is fixedly connected to the side wall of the upper ring 131 or the lower ring 132.

[0045] In the above embodiments, the placement frame facilitates the direct placement and disassembly of the settling cylinder 2. The upper and lower rings 131 and 132 limit the outer wall of the settling cylinder 2 to fix its position. The telescopic rod 12 can adjust the settling cylinder 2 to different heights, for example, 100-200cm. A height of 100cm is the minimum for most atmospheric microplastic sampling. Considering that if the sampler is placed on a rooftop, a lower height reduces the risk of it being blown over by the wind, and rooftops generally have less wind and sand, the microplastic samples collected at a lower height are cleaner with fewer fine sand and gravel impurities. If the base 11 cannot be screwed onto the rooftop... For fixed locations lacking drilling conditions, stones can be used for direct fixation. This simulates the breathing height of people dining, working, and studying at a seated position. Analysis of microplastic samples collected at this height allows for research into the impact of microplastics on the human respiratory system. A height of 150cm is the ideal human breathing height for more scientific research on the harm of atmospheric microplastics to humans, and it is also the sampling height used by most researchers. A height of 200cm is suitable for areas with severe desertification and high wind and sand intensity. A higher height reduces the impact of windblown sand deposition, resulting in cleaner microplastic samples and reducing the workload of subsequent microplastic flotation.

[0046] At the same time, samplers at different heights can be placed at the same sampling point to conduct research on atmospheric microplastics at different heights. The telescopic pole 12, which is lowered to 100cm, is also more convenient to carry when going out.

[0047] Further, refer to Figure 8 Both the upper ring 131 and the lower ring 132 are fixedly connected to the output end of the telescopic rod 12 via a truss.

[0048] Furthermore, the cleaning solution 4 used to fill the storage tank 3 is a hydrogen peroxide solution.

[0049] In the above embodiments, by limiting the cleaning solution 4 to hydrogen peroxide solution, the rinsing effect can be achieved while the impurities can be dissolved. Atmospheric deposition microplastics need to be dissolved. Traditional deposition samplers require the deposition tank 2 to be taken back to the laboratory for subsequent dissolution, but this deposition sampler can directly dissolve the dissolution solution, such as 30% hydrogen peroxide, in situ.

[0050] The size of microplastics is defined as 1μm to 5mm, while particles <1μm are nanoplastics. A 5mm filter automatically removes large particles and retains microplastics or other tiny impurities smaller than 5mm, eliminating the need for manual screening to remove plastics or other impurities larger than 5mm and optimizing the initial screening process.

[0051] Further, refer to Figure 6 The mesh size of screen 52 is 4mm to 5mm.

[0052] In the above embodiments, by limiting the size of the filter screen, impurities with a particle size greater than 4mm or 5mm, such as insects, leaves, and gravel, can be automatically screened out, thereby initially screening out sediments with a particle size length of less than 4mm or 5mm. If there are many dead leaves and insects in the sampling environment, the filter screen can be cleaned once a day.

[0053] Further, refer to Figure 1 The upper end of the settling cylinder 2 is equipped with a cover for sealing, which can be used for subsequent classification and collection of dry and wet microplastics.

[0054] In the above embodiments, specifically regarding dry and wet sampling, normal collection is usually carried out when it is not raining.

[0055] Preparation before sampling: Assemble the equipment: fix the base 11 in sequence, install the telescopic rod 12, adjust the height of the telescopic rod 12, install the sedimentation cylinder 2, detachably connect the collar 51 with the internal screen 52, and finally install the collection bottle 6.

[0056] For dry sedimentation, approximately 100 ml of cleaning solution 4 with a 30% hydrogen peroxide content is injected into sedimentation tank 2 through storage tank 3. The cleaning solution rinses the edges, inner walls, and bottom of sedimentation tank 2 through the spray hole 321 of end cap 32. After passing through the screen 52 of collar 51, the rinsing solution carries the attached microplastics into collection bottle 6. The 30% hydrogen peroxide content cleaning solution 4 usually requires 24 to 72 hours for organic matter to dissolve. During transportation, the collection bottle 6 is in the process of dissolution, which improves the efficiency of subsequent treatment.

[0057] The above-disclosed embodiments are only a few specific examples of the present utility model. However, the embodiments of the present utility model are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the protection scope of the present utility model.

Claims

1. An atmospheric microplastic sedimentation sampler, comprising a sedimentation cylinder (2) connected to a support (1), characterized in that, The lower opening of the settling cylinder (2) further includes: The storage tank (3) is rotatably connected to one side of the bracket (1). The storage tank (3) is used to fill the cleaning liquid (4). A turning rod (7) is fixedly connected to the side wall of the storage tank (3). The other end of the turning rod (7) is rotatably connected to the bracket (1) through a hinge frame (8). As the storage tank (3) rotates upward to above the settling cylinder (2), its outlet (31) is aligned with the settling cylinder (2). The filter assembly (5) includes a collar (51) detachably connected to the lower opening of the settling cylinder (2) and a screen (52) disposed within the collar (51) for screening impurities; A collection bottle (6) is detachably connected to the lower part of the collar (51) for collecting the sieved mixture.

2. The atmospheric microplastic deposition sampler as described in claim 1, characterized in that, The settling cylinder (2) has a cylindrical body and a tapered constriction near the lower opening. The size of the collar (51) matches the size of the lower opening of the settling cylinder (2).

3. An atmospheric microplastic deposition sampler as described in claim 2, characterized in that, The lower opening of the settling cylinder (2) and the opening of the collection bottle (6) are both provided with external threads. The collar (51) is provided with internal threads on the upper and lower inner walls of the screen (52) respectively, which are threaded to the settling cylinder (2) and the collection bottle (6).

4. An atmospheric microplastic deposition sampler as described in claim 1, characterized in that, The end cap (32) of the outlet (31) of the liquid storage tank (3) is detachably connected. The end cap (32) is evenly provided with a number of spray holes (321) along its thickness direction to spray the cleaning liquid (4) inside. A piston (33) is inserted inside the liquid storage tank (3). A counterweight (34) is fixedly connected to one end of the piston (33) away from the outlet (31). When the liquid storage tank (3) rotates upward to above the settling cylinder (2), the counterweight (34) sprays the cleaning liquid (4) out through the spray holes (321) by gravity.

5. An atmospheric microplastic deposition sampler as described in claim 4, characterized in that, The end of the storage tank (3) away from the outlet (31) is detachably connected to a retaining ring for preventing the piston (33) from falling off.

6. An atmospheric microplastic deposition sampler as described in claim 5, characterized in that, Each of the outermost spray holes (321) of the end cap (32) is connected to a hollow conduit (35) for guiding the cleaning fluid (4) toward the inner wall of the settling tank (2).

7. An atmospheric microplastic deposition sampler as described in claim 4, characterized in that, The support (1) includes: The base (11) is provided with anchor bolts for connecting to the ground; The telescopic rod (12) is vertically fixed to the upper part of the base (11); The placement frame includes an upper ring sleeve (131) and a lower ring sleeve (132) that are both fixedly connected to the top of the output end of the telescopic rod (12). The upper ring sleeve (131) is located above the lower ring sleeve (132). The inner ring size of the upper ring sleeve (131) is larger than the outer diameter of the cylindrical part of the settling cylinder (2). The inner ring size of the upper ring sleeve (131) is larger than the inner ring size of the lower ring sleeve (132). It is used for the longitudinal placement of the settling cylinder (2). The hinge frame (8) is fixedly connected to the side wall of the upper ring sleeve (131) or the lower ring sleeve (132).

8. An atmospheric microplastic deposition sampler as described in claim 1, characterized in that, The cleaning solution (4) used to fill the storage tank (3) is a hydrogen peroxide solution.

9. An atmospheric microplastic deposition sampler as described in claim 1, characterized in that, The sieve mesh (52) has a mesh size of 4 mm to 5 mm.

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