A method and device for promoting artificial wetlands to denitrify lake water

Abstract

The present invention relates to the technical field of sewage treatment, and discloses a method for promoting denitrification of lake water by artificial wetlands, comprising the following steps: without damaging the water body condition, a control device for regulating plant root secretion and oxygen supply is arranged in the artificial wetland, and the carbon source is supplemented to the artificial wetland by the control device, the carbon-nitrogen ratio is increased, the root microorganism secretion is promoted, and oxygen is supplied to the plant root system. The present invention also provides a device for promoting denitrification of lake water by artificial wetlands. The present invention can promote the release of plant root secretions by adding microbial agents, sugars and organic acids to the roots of aquatic plants and supplying oxygen to the plant roots, and promote the nitrification and denitrification of rhizosphere microorganisms by regulating the concentration and oxygen supply capacity of the rhizosphere secretions of wetland plants, thereby improving the denitrification capacity of artificial wetlands for lake water.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a method and a device for promoting artificial wetlands to denitrify lake water. Background Art

[0002] In recent years, nitrogen has been an important cause of eutrophication in many lakes. Various forms of nitrogen compounds can lead to eutrophication of water bodies, promote abnormal proliferation of algae, and release harmful substances, thus causing a decline in the water environment quality of urban lakes and an imbalance in the ecosystem.

[0003] Constructed wetlands are artificial sewage treatment systems built using the material cycle and energy flow of plants, microorganisms and substrates in the ecosystem. They are simple to manage and have low operating costs. Studies have shown that the nitrogen removal pathways in wetland systems mainly include ammonia volatilization, medium precipitation adsorption, microbial nitrification / denitrification, and plant absorption. Microbial nitrification and denitrification are generally considered to be the most important pathways for wetland nitrogen removal, with a removal rate of up to 60%-95%. The nitrification process refers to the process in which ammonia nitrogen is first converted into nitrite under aerobic conditions by nitrite bacteria, and then nitrite is converted into nitrate under the action of nitrifying bacteria. The denitrification process is carried out under anoxic conditions and refers to the reduction of nitrate to nitrogen gas by denitrifying bacteria through a series of intermediates (NO2-, NO, N2O). In the denitrification process of artificial wetlands, the rates of nitrification and denitrification need to be balanced to achieve the maximum denitrification efficiency.

[0004] Root exudates refer to a series of chemical substances released into the external environment during the normal growth of plants. High molecular weight compounds include mucus, proteins, etc., and low molecular weight organic compounds include amino acids, organic acids, sugars, phenols and secondary metabolites. Amino acids and sugar compounds secreted by roots can be used as chemical attractants to attract the colonization of plant growth promoting bacteria (PGPR). Some species of these PGPR can use tryptophan secreted by roots to synthesize plant growth hormones. Root exudates play an important role in promoting plant growth, nutrient activation, and improving environmental stress.

[0005] The present invention proposes a method for promoting denitrification of urban lake water based on the denitrification mechanism of wetland plants. The method mainly promotes nitrification and denitrification of root microorganisms by regulating the concentration and oxygen supply capacity of wetland plant root secretions, thereby improving the denitrification capacity of artificial wetlands for lake water. Summary of the invention

[0006] The purpose of the present invention is to propose a method and device for promoting the denitrification of lake water by artificial wetlands based on the denitrification mechanism of wetland plants. The method mainly promotes the nitrification and denitrification of root microorganisms by regulating the concentration and oxygen supply capacity of wetland plant root secretions, thereby improving the denitrification capacity of artificial wetlands for lake water.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for promoting the denitrification of lake water by artificial wetlands is designed. By regulating the concentration and oxygen supply capacity of wetland plant root secretions, the nitrification and denitrification of root microorganisms are promoted, thereby improving the denitrification capacity of artificial wetlands for lake water. The method specifically includes the following steps:

[0009] Step 1: Plant plants with strong root secretion release ability on artificial wetlands;

[0010] Step 2: Under the premise of not damaging the water body, a control device for regulating plant root secretion and oxygen supply is arranged in the artificial wetland;

[0011] Step 3: Regularly adding sugars, organic acids, and microbial agents to the artificial wetland through the control device in step 1 to supplement the carbon source, increase the carbon-nitrogen ratio, and promote the secretion of root microorganisms;

[0012] Step 4: Set up multiple monitoring points for the artificial wetland to detect the oxygen content in the water in real time. When the measured parameter exceeds the set threshold, start the control device to aerate the artificial wetland to supply oxygen to the plant roots to promote microbial nitrification.

[0013] Furthermore, in step 1, the plants are emergent plants and floating plants combined in any proportion.

[0014] Furthermore, in step 2, the control device adopts a continuous distribution method to carry out an overall layout of the artificial wetland.

[0015] Compared with the prior art, the method proposed by the present invention to promote the denitrification of lake water by artificial wetlands has the following beneficial effects: the present invention can promote the release of plant root secretions by adding microbial agents, sugars and organic acids to the roots of aquatic plants and supplying oxygen to the plant roots, and promote the nitrification and denitrification of rhizosphere microorganisms by regulating the concentration and oxygen supply capacity of rhizosphere secretions of wetland plants, thereby improving the denitrification capacity of artificial wetlands for lake water. Specifically:

[0016] (1) The present invention increases the denitrification effect of root-attached microorganisms by adding microbial agents to promote the concentration of root microorganisms.

[0017] (2) The present invention appropriately supplements carbon sources to artificial wetlands without damaging the water body condition, increases the carbon-nitrogen ratio in artificial wetlands by adding sugars and organic acids to plant roots, and promotes the release of plant root secretions to provide microbial denitrification.

[0018] (3) The present invention regulates the oxygen content in the artificial wetland by supplying oxygen to the plant roots, promotes the digestion of microorganisms, balances the rates of nitrification and denitrification, and is beneficial to improving the denitrification efficiency of wetland plants.

[0019] The present invention also proposes a device for promoting denitrification of lake water by artificial wetlands, which is used to implement any of the above-mentioned methods for promoting denitrification of lake water by artificial wetlands, comprising a control cabinet and a plurality of adding devices distributed in the artificial wetland, wherein the adding devices are connected in series with each other through a conduit; a controller, an air pump and a water pump connected to the controller through a wire are arranged in the control cabinet, the input end of the water pump is respectively connected to a carbon source adding tank and a microbial agent adding tank through pipe fittings, and a first electromagnetic valve and a second electromagnetic valve are respectively arranged on the pipe fittings connecting the tank bodies, the output ends of the air pump and the water pump are respectively connected to the conduit through pipe fittings, and a second electromagnetic valve is respectively arranged on the pipe fittings connecting the conduit There are a third electromagnetic valve and a fourth electromagnetic valve; it also includes a monitor for detecting the oxygen content of the artificial wetland, the monitor is distributed in the artificial wetland, and is connected to the controller wirelessly, and the controller and the monitor are provided with a wireless transceiver module for wireless connection; the adding device includes an upper adding tube and a lower adding tube, a connecting tube is provided between the upper adding tube and the lower adding tube, and an inlet and an outlet for connecting the conduit are respectively provided on both sides of the upper part of the upper adding tube; a plurality of upper nozzles are evenly distributed on the upper adding tube, and a plurality of lower nozzles are evenly distributed on the lower adding tube; a partition is provided at the lower part of the upper adding tube, and a self-closing mechanism is provided on the partition.

[0020] Furthermore, the openings of the upper nozzle and the lower nozzle are both arranged to be inclined upward.

[0021] Furthermore, the connecting pipe adopts a multi-section structure, and the connecting pipes are connected by threads.

[0022] Furthermore, the self-closing mechanism includes a valve, which is arranged in a bucket shape on a partition, a support portion is fixedly provided on the top of the valve, a lifting rod is passed through the support portion, a float is fixedly provided on the top of the lifting rod, a valve plug is provided at the bottom of the lifting rod, the valve plug is adapted to the size of the inner cavity of the valve, a through hole is provided on the circumference of the valve, and a counterweight is fixedly provided at the bottom of the valve plug.

[0023] Furthermore, a handle is fixedly provided on the top of the upper adding tube.

[0024] Furthermore, a fixed bottom leg is provided at the bottom of the lower adding pipe. The fixed bottom leg is a rod-shaped structure and is provided with a plurality of claw hooks along the length direction.

[0025] The invention proposes a device for promoting artificial wetlands to denitrify lake water, which has the following beneficial effects:

[0026] (1) The present invention uses multiple adding devices, which are distributed in the artificial wetland, to add microbial agents, sugars and organic acids to the roots of aquatic plants and to supply oxygen to the plant roots, thereby promoting the release of plant root secretions. By regulating the concentration and oxygen supply capacity of the rhizosphere secretions of wetland plants, the nitrification and denitrification of rhizosphere microorganisms are promoted, thereby improving the denitrification capacity of artificial wetlands for lake water.

[0027] (2) The addition device of the present invention adopts an upper and lower pipe structure, which can supply oxygen to the roots of emergent plants and floating plants at the same time. As for the addition of microbial agents, sugars and organic acids, the self-closing mechanism arranged in the upper addition pipe blocks the liquid from flowing into the lower addition pipe, and only adds to the water body, so that the added microbial agents, sugars and organic acids directly act on the roots of floating plants, promote the release concentration of root secretions in the water body, provide nitrification and denitrification of microorganisms, and thus improve the denitrification capacity of artificial wetlands for lake water. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 It is a schematic diagram of the structure of a device for promoting artificial wetlands to denitrify lake water in the present invention;

[0030] Figure 2 It is a structural schematic diagram of the adding device in the present invention;

[0031] Figure 3 It is a schematic diagram of the internal structure of the adding device in the present invention;

[0032] Figure 4 It is an enlarged schematic diagram of the self-closing mechanism in the present invention;

[0033] Marked in the figure: In the figure: 1, control cabinet, 11, air pump, 12, water pump, 13, controller; 2, carbon source adding tank; 3, microbial agent adding tank; 41, first electromagnetic valve, 42, second electromagnetic valve, 43, third electromagnetic valve, 44, fourth electromagnetic valve; 5, adding device, 51, upper adding pipe, 511, upper nozzle, 512, inlet, 513, outlet, 514, partition, 52, lower adding pipe, 521, lower nozzle, 53, connecting pipe, 54, fixed bottom leg, 541, claw hook, 55, handle; 6, catheter; 7, self-closing mechanism, 71, valve, 72, support part, 73, lifting rod, 74, through hole, 75, float, 76, valve plug, 77, counterweight; 8, detection device. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] The structural features of the present invention are now described in detail with reference to the accompanying drawings.

[0038] Example 1

[0039] A method for promoting artificial wetlands to denitrify lake water, the method specifically comprising the following steps: planting plants with strong root secretion release ability on artificial wetlands, the plants are emergent plants and floating plants in any proportion, the roots of the emergent plants are located in the soil matrix layer, the floating plants are located in the water quality, the emergent plants are one or more of cattail, loosestrife, water plantain, water lily, and pickerel grass with well-developed root systems, and the floating plants are water hyacinth or water chestnut with well-developed fibrous roots. Under the premise of not destroying the water body condition, a control device for regulating plant root secretion and oxygen supply is arranged in the artificial wetland, the control device adopts a continuous distribution mode, and the artificial wetland is arranged as a whole, specifically, a serpentine structure layout can be adopted, and the layout is arranged according to the terrain of the artificial wetland, so that the control device arranged in this way is not easy to have dead corners, and the addition of microbial agents, sugars and organic acids to the roots of aquatic plants and the oxygen supply to the roots of plants are also relatively uniform. According to the needs of artificial wetlands, sugars, organic acids, and microbial agents are regularly added to artificial wetlands through control devices to supplement carbon sources, increase the carbon-nitrogen ratio, and promote root microbial secretion. The amount of addition is determined by the water quality test content of artificial wetlands. Multiple monitoring points are set for artificial wetlands to detect the oxygen content in the water in real time. When the measured parameters exceed the set threshold, the control device is started to aerate the artificial wetlands and supply oxygen to the plant roots to promote microbial nitrification.

[0040] Example 2

[0041] See also Figure 1 The present invention also proposes a device for promoting denitrification of lake water by artificial wetlands, which is used to implement a method for promoting denitrification of lake water by artificial wetlands, including a control cabinet 1 and a plurality of adding devices 5 distributed in the artificial wetland, the adding devices 5 are connected in series with each other through a conduit 6, including a control cabinet 1 fixedly arranged outside the artificial wetland and connected to the mains, the adding devices 5 are distributed in the artificial wetland in a serpentine structure, and the adding devices 5 are placed as close as possible to areas with dense growth of aquatic plants.

[0042] See also Figure 1The control cabinet 1 is provided with a controller 13, an air pump 11 and a water pump 12 connected to the controller 13 through wires, the input end of the water pump 12 is connected to the carbon source addition tank 2 and the microbial agent addition tank 3 through pipe fittings, and the pipe fittings connecting the tank bodies are respectively provided with a first electromagnetic valve 41 and a second electromagnetic valve 42, the output ends of the air pump 11 and the water pump 12 are respectively connected to the conduit 6 through pipe fittings, and the pipe fittings connecting the conduit 6 are respectively provided with a third electromagnetic valve 43 and a fourth electromagnetic valve 44, the carbon source addition tank 2 contains a mixed solution of sugars and organic acids, which is used to provide a carbon source for aquatic plants in artificial wetlands to adjust the carbon-nitrogen ratio of water quality, the microbial agent addition tank 3 contains a microbial agent solution, which is used to provide microbial agents to aquatic plants in artificial wetlands and increase the concentration of microorganisms, the air pump 11 is used to supply oxygen to aquatic plants in artificial wetlands, and in actual operation, the controller 13 controls The first electromagnetic valve 41, the second electromagnetic valve 42, the third electromagnetic valve 43 and the fourth electromagnetic valve 44, when it is necessary to add a carbon source, the controller controls to open the first electromagnetic valve 41 and the third electromagnetic valve 43, and close the second electromagnetic valve 42 and the fourth electromagnetic valve 44. At this time, the water pump 12 is connected to the carbon source addition tank 2 to add a carbon source to the aquatic plants in the artificial wetland. When it is necessary to add microbial agents, the controller controls to open the second electromagnetic valve 42 and the third electromagnetic valve 43, and close the first electromagnetic valve 41 and the fourth electromagnetic valve 44. At this time, the water pump 12 is connected to the microbial agent addition tank 3 to add microbial agents to the aquatic plants in the artificial wetland. When oxygen supply is needed, the controller controls to open the fourth electromagnetic valve 44, and close the first electromagnetic valve 41, the second electromagnetic valve 42 and the third electromagnetic valve 43. At this time, the air pump 11 supplies oxygen to the aquatic plants in the artificial wetland.

[0043] See also Figure 1 , and also includes a monitor 8 for detecting oxygen content in the artificial wetland. The monitor 8 is an oxygen content detector. The monitor 8 is distributed in the artificial wetland and is connected to the controller 13 in a wireless manner. The controller 13 and the monitor 8 are provided with a wireless transceiver module for wireless connection. When the monitor 8 detects that the oxygen content is lower than the set threshold, the controller will control the opening of the fourth electromagnetic valve 44 and the closing of the first electromagnetic valve 41, the second electromagnetic valve 42 and the third electromagnetic valve 43 to supply oxygen to the aquatic plants in the artificial wetland.

[0044] See also Figure 2-3The adding device 5 includes an upper adding tube 51 and a lower adding tube 52. A handle 55 is fixedly provided on the top of the upper adding tube 51. A fixed bottom leg 54 is provided at the bottom of the lower adding tube 52. The fixed bottom leg 54 is a rod-shaped structure and is provided with a plurality of claw hooks 541 along the length direction. The upper adding tube 51 and the lower adding tube 52 are gourd-shaped. The upper adding tube 51 is used to provide carbon sources, microbial agents or oxygen for aquatic plants with roots in the water. The lower adding tube 52 is used to provide oxygen for aquatic plants with roots in the soil. A connecting tube 53 is provided between the upper adding tube 51 and the lower adding tube 52. The upper adding tube 51 and the lower adding tube 52 are connected through the connecting tube 53. The connecting tube 53 adopts a multi-section structure. The connecting tubes 53 are connected by threads. The distance between the upper adding tube 51 and the lower adding tube 52 is adjusted by adjusting the number of connecting tubes 53. The number of connecting tubes 53 is adjusted manually. Determined by the water depth of the wetland, an inlet 512 and an outlet 513 for connecting to the conduit 6 are respectively provided on both sides of the upper part of the upper adding pipe 51, a plurality of upper nozzles 511 are evenly distributed on the upper adding pipe 51, and a plurality of lower nozzles 521 are evenly distributed on the lower adding pipe 52. The openings of the upper nozzles 511 and the lower nozzles 521 are both inclined upward. The openings are both inclined upward to avoid the soil sealing the nozzles when inserted into the soil. Since the lower nozzles 521 are subject to greater resistance from the soil, in order to increase the oxygen supply in the soil, the density of the lower nozzles 521 should be greater than the density of the upper nozzles 511. During specific operation, the adding device 5 is pressed into the water by the handle 55, so that the adding device 5 is as close to the root position of the aquatic plants as possible, and the degree of downward pressure is such that the lower adding pipe 52 is completely inserted into the mud layer. The adding device 5 can be stably fixed at the specified position under the action of the fixed bottom legs 54.

[0045] See also Figure 4A partition 514 is provided at the lower part of the upper adding pipe 51, and a self-closing mechanism 7 is provided on the partition 514. The self-closing mechanism 7 includes a valve 71, and the valve 71 is arranged on the partition 514 in a bucket shape. A support portion 72 is fixedly provided on the top of the valve 71, and a lifting rod 73 is penetrated through the support portion 72. A floating ball 75 is fixedly provided on the top of the lifting rod 73, and a valve plug 76 is provided at the bottom of the lifting rod 73. The valve plug 76 is adapted to the size of the inner cavity of the valve 71. A through hole 74 is provided on the circumference of the valve 71, and a counterweight block 77 is fixedly provided at the bottom of the valve plug 76. After the water level in the upper adding pipe 51 changes, the valve plug 76 can be closed on the valve 71 through the floating ball 75. When adding carbon source or microbial agent to the root system of aquatic plants, it is mainly aimed at aquatic plants whose roots are in the water. When adding, the upper adding tube 51 will be filled with solution, and the float 75 will float upward, driving the valve plug 76 to seal the valve 71, so that the solution cannot flow into the lower adding tube 52. When supplying oxygen to the root system, whether the root system is in the water or in the soil, oxygen supply is required. At this time, since the upper adding tube 51 is flowing with high-pressure gas, the valve plug 76 is separated from the valve 71 under the action of the counterweight block 77 and the high pressure inside the upper adding tube 51, so that the high-pressure airflow enters the lower adding tube 52, and oxygen is supplied to the roots in the soil through the lower nozzle 521.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for promoting denitrification of lake water by artificial wetlands, which is used to implement a method for promoting denitrification of lake water by artificial wetlands, and promotes nitrification and denitrification of root microorganisms by regulating the concentration and oxygen supply capacity of wetland plant root secretions, thereby improving the denitrification capacity of artificial wetlands for lake water. The method specifically comprises the following steps: Step 1: Plant plants with strong root secretion release ability on artificial wetlands; The plants are emergent plants and floating plants in any proportion; Step 2: Under the premise of not damaging the water body condition, a control device for regulating plant root secretion and oxygen supply is arranged in the artificial wetland; The control devices are distributed continuously to make an overall layout of the artificial wetland; Step 3: Regularly adding sugars, organic acids, and microbial agents to the artificial wetland through the control device in step 1 to supplement the carbon source, increase the carbon-nitrogen ratio, and promote the secretion of root microorganisms; Step 4: multiple monitoring points are set for the artificial wetland to detect the oxygen content in the water in real time. When the measured parameter exceeds the set threshold, the control device is started to aerate the artificial wetland to supply oxygen to the plant roots to promote microbial nitrification; It is characterized in that It comprises a control cabinet (1) and a plurality of adding devices (5) distributed in the artificial wetland, wherein the adding devices (5) are connected in series with each other via a conduit (6); The control cabinet (1) is provided with a controller (13), an air pump (11) and a water pump (12) connected to the controller (13) via a wire; the input end of the water pump (12) is respectively connected to a carbon source addition tank (2) and a microbial agent addition tank (3) via pipe fittings, and the pipe fittings connecting the tank bodies are respectively provided with a first electromagnetic valve (41) and a second electromagnetic valve (42); the output ends of the air pump (11) and the water pump (12) are respectively connected to a conduit (6) via pipe fittings, and the pipe fittings connecting the conduit (6) are respectively provided with a third electromagnetic valve (43) and a fourth electromagnetic valve (44); Also included is a monitor (8) for detecting oxygen content in the artificial wetland, wherein the monitor (8) is distributed in the artificial wetland and is connected to the controller (13) in a wireless manner, and a wireless transceiver module for wireless connection is provided in the controller (13) and the monitor (8); The adding device (5) comprises an upper adding pipe (51) and a lower adding pipe (52), a connecting pipe (53) is provided between the upper adding pipe (51) and the lower adding pipe (52), and an inlet (512) and an outlet (513) for connecting to the conduit (6) are respectively provided on both sides of the upper part of the upper adding pipe (51); The upper adding pipe (51) is evenly distributed with a plurality of upper nozzles (511), and the lower adding pipe (52) is evenly distributed with a plurality of lower nozzles (521), and the openings of the upper nozzles (511) and the lower nozzles (521) are both arranged to be inclined upward; A partition plate (514) is provided at the lower part of the upper adding pipe (51), and a self-closing mechanism (7) is provided on the partition plate (514); The self-closing mechanism (7) comprises a valve (71), the valve (71) is arranged on the partition (514) in a bucket shape, a support portion (72) is fixedly provided on the top of the valve (71), a lifting rod (73) is passed through the support portion (72), a floating ball (75) is fixedly provided on the top of the lifting rod (73), a valve plug (76) is provided at the bottom of the lifting rod (73), the valve plug (76) is adapted to the size of the inner cavity of the valve (71), a through hole (74) is provided on the circumference of the valve (71), and a counterweight block (77) is fixedly provided at the bottom of the valve plug (76).

2. The device for promoting denitrification of lake water by artificial wetlands according to claim 1, characterized in that: The connecting pipe (53) adopts a multi-section structure, and the connecting pipes (53) are connected by threads.

3. The device for promoting denitrification of lake water by artificial wetlands according to claim 1, characterized in that: A handle (55) is fixedly provided on the top of the upper adding tube (51).

4. The device for promoting denitrification of lake water by artificial wetlands according to claim 1, characterized in that: A fixed bottom leg (54) is provided at the bottom of the lower adding pipe (52); the fixed bottom leg (54) is a rod-shaped structure and is provided with a plurality of claw hooks (541) along the length direction.

Images