Vertical flow constructed wetland

Abstract

The present application relates to a vertical flow artificial wetland, which gradually reduces the vertical spacing between the water distribution pipe and the water collection pipe. Since the water flow velocity at the front end of the water collection pipe is faster than the water flow velocity at the end of the water collection pipe, the vertical movement distance is increased, thereby extending the front end water flow movement time and shortening the end water flow movement time, thereby shortening the difference in the running time of the front end water flow and the end water flow in the artificial wetland, so that the water flow at each position can reach the outlet at nearly the same time, so that all water flows are uniformly pushed in the packing bed like a piston flow, which can improve the water distribution efficiency and treatment efficiency. At the same time, since the front end water flow movement time is increased, the water flow velocity at the front end of the water collection pipe can be slowed down, thereby reducing the drainage velocity difference between the front end of the water collection pipe and the end of the water collection pipe, reducing the possibility of poor drainage caused by the front end water flow forming a supporting effect on the end water flow, slowing down the blockage phenomenon in the artificial wetland, and ensuring the hydraulic efficiency of the vertical flow artificial wetland.

Description

Technical Field

[0001] The present application relates to the technical field of artificial wetland water treatment, and in particular to vertical flow artificial wetlands. Background Art

[0002] Currently, removing nitrogen and phosphorus pollutants from water bodies is a challenge in wastewater purification. Constructed wetlands are artificially constructed and controlled wetlands similar to swamps. Constructed wetland wastewater treatment ecosystems treat and purify wastewater and sludge through the synergistic effects of soil layers, artificial media, plants, and microorganisms, allowing wastewater to flow in a specific direction under human intervention.

[0003] Vertical flow constructed wetlands are a low-cost, ecological and efficient water treatment technology and are widely used in the field of sewage treatment.

[0004] In related technologies, the hydraulic efficiency of vertical flow artificial wetlands is low, which affects their treatment efficiency. Summary of the Invention

[0005] Based on this, it is necessary to provide a vertical flow artificial wetland to address the problem of low hydraulic efficiency of existing vertical flow artificial wetlands.

[0006] A vertical flow artificial wetland, comprising:

[0007] The packed bed comprises a first packing layer, a second packing layer and a third packing layer arranged in sequence along the flow direction of water in the packed bed;

[0008] A water distribution pipe is provided in the first packing layer; the water distribution pipe is provided with a plurality of water distribution holes along the water flow direction of the water distribution pipe to introduce sewage into the packing bed;

[0009] a water collecting pipe, arranged in the third packing layer, and provided with a plurality of water collecting holes along the water flow direction of the water collecting pipe, so as to collect the treated water after being treated by the packing bed and lead the treated water out of the packing bed;

[0010] Along the water flow direction of the water distribution pipe, the vertical distance between the water distribution pipe and the water collecting pipe gradually decreases.

[0011] In one embodiment, along the water flow direction of the water distribution pipe, the apertures of the plurality of water distribution holes increase in sequence; and / or,

[0012] Along the water flow direction of the water collecting pipe, the apertures of the plurality of water collecting holes increase sequentially.

[0013] In one embodiment, along the water flow direction of the water distribution pipe, the density of the plurality of water distribution holes decreases sequentially; and / or,

[0014] Along the water flow direction of the water collecting pipe, the density of the plurality of water collecting holes decreases successively.

[0015] In one embodiment, the extension direction of the water distribution pipe forms an angle with the direction of gravity, and the angle is an acute angle.

[0016] In one embodiment, the elevation of the front end of the water distribution pipe is higher than the elevation of the end end of the water distribution pipe.

[0017] In one embodiment, the flow direction of the water in the packing bed forms an angle with the extension direction of the water collecting pipe, and the angle is an obtuse angle.

[0018] In one embodiment, the vertical flow artificial wetland includes a downflow vertical flow artificial wetland and an upflow vertical flow artificial wetland;

[0019] In the downflow vertical flow artificial wetland, the elevation of the front end of the water collecting pipe is lower than the elevation of the end end of the water collecting pipe;

[0020] In the upward vertical flow artificial wetland, the elevation of the front end of the water collecting pipe is higher than the elevation of the end end of the water collecting pipe.

[0021] In one embodiment, the filler particle size of the first filler layer is larger than the filler particle size of the second filler layer, and smaller than the filler particle size of the third filler layer.

[0022] In one embodiment, along the water flow direction of the water distribution pipe, the filler porosity of the first filler layer gradually decreases; and / or,

[0023] Along the water flow direction of the water distribution pipe, the filler porosity of the second filler layer gradually decreases; and / or,

[0024] Along the water flow direction of the water distribution pipe, the filler porosity of the third filler layer gradually decreases.

[0025] In one embodiment, along the water flow direction of the water distribution pipe, the filler particle size of the first filler layer gradually decreases; and / or,

[0026] Along the water flow direction of the water distribution pipe, the filler particle size of the second filler layer gradually decreases; and / or,

[0027] Along the water flow direction of the water distribution pipe, the filler particle size of the third filler layer gradually decreases.

[0028] The above-mentioned vertical flow artificial wetland is simple to construct and highly efficient. By setting the vertical spacing between the water distribution pipe and the water collection pipe to gradually decrease, that is, the vertical movement distance of the front water flow in the packing bed is greater than the vertical movement distance of the end water flow in the packing bed. Since the water flow speed at the front end of the water collection pipe is faster than the water flow speed at the end of the water collection pipe, by increasing its vertical movement distance, the front water flow movement time is extended and the end water flow movement time is shortened, thereby shortening the difference in the running time of the front water flow and the end water flow inside the artificial wetland, so that the water flow at each position can reach the outlet at nearly the same time, so that all water flows are uniformly pushed in the packing bed like piston flow, which can improve the water distribution efficiency and treatment efficiency. At the same time, since the front water flow movement time is increased, the water flow speed at the front end of the water collection pipe can be slowed down, thereby reducing the difference in drainage speed between the front end of the water collection pipe and the end of the water collection pipe, reducing the possibility of the front water flow forming a supporting effect on the end water flow, resulting in poor drainage, slowing down the blockage phenomenon in the artificial wetland, and ensuring the hydraulic efficiency of the vertical flow artificial wetland. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the vertical flow artificial wetland provided in the first embodiment of the present application.

[0030] Figure 2 for Figure 1 Schematic diagram of the water distribution pipes in the vertical flow constructed wetland shown.

[0031] Figure 3 Schematic diagram of the vertical flow artificial wetland provided in the second embodiment of the present application.

[0032] Reference numerals: 110, first packing layer; 120, second packing layer; 130, third packing layer; 210, water distribution pipe; 211, water distribution hole; 310, water collection pipe; 311, water collection hole. DETAILED DESCRIPTION

[0033] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0034] In the description of this application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0035] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, if the term "plurality" appears, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0036] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connected," "fixed," etc., should be interpreted broadly. For example, these terms may refer to fixed connections, removable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; and internal communication between two components or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0037] In this application, unless otherwise expressly specified or limited, if a first feature is described as being "above" or "below" a second feature, or similar descriptions, this may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is described as being "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is described as being "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0038] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only embodiment.

[0039] Vertical flow constructed wetlands, as a low-cost, ecological, and highly efficient water treatment technology, are widely used in wastewater treatment. However, improving the water distribution efficiency of vertical flow constructed wetlands has been a focus of considerable research. Studies have reported that the "dead water zone" in surface flow constructed wetlands ranges from 15% to 25% (with a filler porosity of 0.55), while it reaches as high as 48% to 72% in downflow-upflow composite vertical flow constructed wetlands. The presence of this dead water zone significantly reduces the water distribution efficiency of constructed wetlands. This suggests that compared to surface flow constructed wetlands, vertical flow constructed wetland systems have a larger dead water zone. This is not only related to the system's hydraulic conditions, but may also be closely related to the system's water distribution. The uniformity of the system's water distribution significantly influences the size of the dead water zone.

[0040] Vertical flow constructed wetlands primarily rely on water distribution pipes buried within the wetland to achieve uniform water distribution. According to hydraulic laws, the farther away from the water inlet of the water distribution pipe, the smaller the total head, the greater the pressure head, and the slower the water flow rate. This means that insurmountable head differences exist within the vertical flow constructed wetland water distribution system, affecting the system's water distribution uniformity. Considering the particle size distribution of commonly used fillers in vertical flow constructed wetlands, which generally follows a small-to-large arrangement from top to bottom, water flows through the water distribution pipes into the filler and is then discharged through the water collection pipe. The head difference in the water distribution pipes can cause the water at the front end of the pipe to be discharged at a faster rate in a shorter period of time, while the water at the end of the pipe flows more slowly. This can cause the water at the front end of the pipe to support the water at the end of the pipe in the water collection pipe, resulting in poor drainage at the end of the pipe and the formation of a "stagnant water zone." Secondly, insufficient head, or insufficient hydraulic load, can prevent water from flowing smoothly into the end of the pipe, forming a "dead water zone" in the constructed wetland. Both "stagnant water zones" and "dead water zones" reduce the hydraulic efficiency of vertical flow constructed wetlands.

[0041] In related technologies, increasing the head pressure (hydraulic load) of the distribution pipes is generally used to improve the water distribution efficiency of vertical flow constructed wetlands. However, research has confirmed that as the inlet flow rate continues to increase (i.e., the head pressure increases), the system will also experience water stagnation. This means that the supporting effect of the water flow at the front end of the distribution pipe on the water flow at the end of the distribution pipe cannot be eliminated by increasing the head pressure. In short, if the hydraulic load is too low, water will not flow to the end, forming a "dead water zone"; if the hydraulic load is too high, the supporting effect will cause poor drainage at the end, forming a "stagnant water zone." Therefore, in the design and operation of vertical flow constructed wetlands, there is theoretically an upper limit to the hydraulic load. The relationship between the hydraulic load, the intermittent inflow and outflow cycles, the substrate permeability, and the diameter of the drainage pipe must be fully considered to avoid water inflow in the next cycle before the water in the previous cycle has completely drained out, causing water accumulation.

[0042] Based on this, the present application provides a vertical flow artificial wetland that can improve hydraulic efficiency and thus ensure sewage treatment efficiency. The vertical flow artificial wetland provided by an embodiment of the present application will be described in detail below with reference to the accompanying drawings.

[0043] See Figure 1 and Figure 2 As shown, the vertical flow artificial wetland provided by one embodiment of the present application includes a packing bed, a water distribution pipe 210 and a water collecting pipe 310. The packing bed includes a first packing layer 110, a second packing layer 120 and a third packing layer 130 arranged in sequence along the flow direction of the water body in the packing bed; the water distribution pipe 210 is arranged in the first packing layer 110; along the water flow direction of the water distribution pipe 210, the water distribution pipe 210 is provided with a plurality of water distribution holes 211 to introduce sewage into the packing bed and enable the sewage to be evenly distributed on the packing bed; the water collecting pipe 310 is provided in the third packing layer 130, along the water flow direction of the water collecting pipe 310, the water collecting pipe 310 is provided with a plurality of water collecting holes 311 to collect the treated water after treatment by the packing bed and lead the treated water out of the packing bed; along the water flow direction of the water distribution pipe 210, the vertical distance between the water distribution pipe 210 and the water collecting pipe 310 gradually decreases. As shown Figure 1 Arrows indicate the direction of water flow in the water distribution pipe 210, the water collection pipe 310 and the packing bed.

[0044] The vertical flow artificial wetland is simple to construct and highly efficient. By gradually reducing the vertical distance between the water distribution pipe 210 and the water collection pipe 310, that is, the front end (i.e. Figure 1 The vertical movement distance of the water flow in the packed bed is greater than that at the end (i.e. Figure 1The vertical movement distance of the water flow in the packing bed (right end in the figure) is increased. Since the water flow velocity at the front end of the water collecting pipe 310 is faster than the water flow velocity at the end of the water collecting pipe 310, by increasing its vertical movement distance, the water flow movement time at the front end is extended and the water flow movement time at the end is shortened, thereby shortening the difference in the running time of the water flow at the front end and the water flow at the end in the artificial wetland, so that the water flow at each position can reach the outlet at nearly the same time, so that all the water flow is evenly pushed in the packing bed like a piston flow, which can improve the water distribution efficiency and treatment efficiency. At the same time, since the water flow movement time at the front end is increased, the water flow velocity at the front end of the water collecting pipe 310 can be slowed down, thereby reducing the difference in drainage velocity between the front end of the water collecting pipe 310 and the end of the water collecting pipe 310, reducing the possibility of the front end water flow supporting the end water flow and causing poor drainage, slowing down the blockage phenomenon in the artificial wetland, and ensuring the hydraulic efficiency of the vertical flow artificial wetland.

[0045] See Figure 2 As shown, in one embodiment, the apertures of the multiple water distribution holes 211 increase in sequence along the water flow direction of the water distribution pipe 210. Since the water flow speed is fast at the front end and slow at the end, the aperture at the front end is set to be small to reduce the front flow rate, and the aperture at the end is set to be large to increase the end flow rate, thereby reducing the flow rate difference between the front end and the end of the water distribution pipe 210, and narrowing the gap in the flow rate of water running inside the artificial wetland. Similarly, for the same reason, along the water flow direction of the water collection pipe 310, the apertures of the multiple water collection holes 311 increase in sequence, thereby reducing the flow rate difference between the front end and the end of the water collection pipe 310.

[0046] See Figure 2 As shown, in one embodiment, along the water flow direction of the water distribution pipe 210, the density of the multiple water distribution holes 211 decreases successively. The density of the water distribution holes 211 decreases successively, that is, the porosity increases gradually, because water always tends to flow from a position with a small porosity to a position with a large porosity. Therefore, by setting the density of the water distribution holes 211 to decrease successively, the water flow at the front end is more likely to flow to the end, thereby reducing the attenuation of the water flow velocity and reducing the difference in the running time of the water flow inside the wetland. Furthermore, along the water flow direction of the water collection pipe 310, the density of the multiple water collection holes 311 decreases successively, that is, the porosity of the water collection holes 311 increases gradually, so as to reduce the difference in water flow velocity between the front end and the end.

[0047] See Figure 1 or Figure 3As shown, in one embodiment, the extension direction of the water distribution pipe 210 forms an acute angle with the direction of gravity. In other words, the water distribution pipe 210 is tilted, which extends the horizontal path length of the front water flow within the water distribution pipe 210, slowing the water flow velocity at the front of the water collection pipe 310 and thus extending the front water flow time. The water distribution pipe 210 is curved slightly downward.

[0048] See Figure 1 or Figure 3 As shown, in one embodiment, the elevation of the front end of the water distribution pipe 210 is higher than the elevation of the end of the water distribution pipe 210. In other words, the water distribution pipe 210 extends downward at an angle, so that the elevation difference between the front end and the end can be utilized to reduce the velocity loss of water flowing from the water distribution pipe 210 to the end by relying on the effect of gravity, narrowing the difference in water inlet velocity between the front end and the end of the water distribution pipe 210, reducing the difference in water flow velocity reaching the front end and the end of the water collection pipe 310, and reducing the possibility of blockage caused by excessive velocity difference between the front end and the end.

[0049] See Figure 1 or Figure 3 As shown in FIG. 1 , in one embodiment, the flow direction of the water in the packing bed forms an angle with the extension direction of the water collecting pipe 310, and the angle is an obtuse angle. Figure 1 As shown, in the downflow vertical flow artificial wetland, the flow direction of the water in the filler bed is downward, and correspondingly, the water collecting pipe 310 extends upward at an angle; Figure 3 As shown, in a downwelling vertical flow constructed wetland, water flows upward within the filler bed, and the water collection pipe 310 extends downward at an angle. By slanting the water collection pipe 310, the horizontal path length of the water flow within the water collection pipe 310 is extended, increasing the contact time between the water and filler, and reducing the difference in drainage velocity between the front and rear ends of the water collection pipe 310.

[0050] Specifically, if Figure 1 As shown, for the downward vertical flow artificial wetland, the water collecting pipe 310 is slightly curved upward, and the elevation of the front end of the water collecting pipe 310 is lower than the elevation of the end of the water collecting pipe 310; Figure 3 As shown, for an upflow vertical flow constructed wetland, the water collecting pipe 310 is slightly curved downward, and the elevation of the front end of the water collecting pipe 310 is higher than the elevation of the end of the water collecting pipe 310. The height difference between the front end and the end of the water collecting pipe 310 reduces the difference in drainage speed between the front end and the end of the water collecting pipe 310.

[0051] See Figure 1 or Figure 3As shown, in one embodiment, the filler particle size of the first filler layer 110 is larger than the filler particle size of the second filler layer 120, and smaller than the filler particle size of the third filler layer 130. That is, the first filler layer 110 is a medium-sized filler layer, which may include sand and gravel. The medium-sized filler layer can provide more surface area for microorganisms, which is conducive to the growth and biodegradation process of microorganisms; the second filler layer 120 is a fine-sized filler layer, which may include sand, fine gravel, etc. The fine-sized filler layer increases the contact time between water and filler, better absorbs and retains nutrients in sewage, and is conducive to the growth and biodegradation process of microorganisms; the third filler layer 130 is a coarse-sized filler layer, which may include gravel, pebbles, etc. The coarse-sized filler layer increases the flow rate and flow velocity of water, better supports the passage of water, and can quickly remove suspended solids in sewage, ensuring that the artificial wetland can operate with a higher effective volume ratio and hydraulic efficiency. For the downward vertical flow artificial wetland, from top to bottom there are medium-sized filler layer, fine-sized filler layer and coarse-sized filler layer. For the downward vertical flow artificial wetland, from bottom to top there are medium-sized filler layer, fine-sized filler layer and coarse-sized filler layer. In this way, the differences in the water flow path, speed and time inside the wetland are shortened, and efficient water distribution is achieved in the vertical flow artificial wetland.

[0052] See Figure 1 or Figure 3 As shown, in one embodiment, the porosity of the packing in the first packing layer 110 gradually decreases along the direction of water flow in the water distribution pipe 210. This arrangement is adopted, on the one hand, to reduce the occurrence of horizontal flow, because water always tends to flow from packing with lower porosity to packing with higher porosity. The water flow at the front end of the water distribution pipe 210 is faster and has a higher flow rate than the water flow at the end. Before the water flow at the end of the water distribution pipe 210 enters the packing, the water flow at the front end has already entered the packing. By setting the porosity to gradually decrease, the movement of water flow at the end into the packing at the front end can be effectively reduced. On the other hand, the water flow velocity and flow rate in the water distribution pipe 210 gradually decrease, and the porosity decreases accordingly, which means that the effective volume of the wetland gradually decreases. This coincides with the gradual decrease in water flow rate, allowing the internal water flow to follow the movement law of "fast flow rate, high porosity, large effective volume, increased movement time; low flow rate, low porosity, reduced movement time", reducing the possibility of horizontal flow and narrowing the difference in the time of water flow within the wetland. In addition, the porosity at the front end of the first filler layer 110 is relatively large, which can effectively alleviate the clogging of the wetland, because the clogging of the wetland is often concentrated in the front part of the wetland, that is, the area near the water inlet.

[0053] Furthermore, along the water flow direction of the water distribution pipe 210, the filler porosity of the second filler layer 120 gradually decreases; along the water flow direction of the water distribution pipe 210, the filler porosity of the third filler layer 130 gradually decreases. Such an arrangement can not only reduce the occurrence of horizontal flow, but also reduce the difference in the running time of water flow inside the wetland.

[0054] See Figure 1 or Figure 3 As shown, in one embodiment, the filler particle size of the first filler layer 110 gradually decreases along the water flow direction of the water distribution pipe 210; the filler particle size of the second filler layer 120 gradually decreases along the water flow direction of the water distribution pipe 210; and the filler particle size of the third filler layer 130 gradually decreases along the water flow direction of the water distribution pipe 210. This reduces the possibility of horizontal flow and narrows the difference in the running time of water flow within the wetland. In addition, the large aperture at the front end of the filler layer can effectively reduce the blockage of the wetland.

[0055] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A vertical flow artificial wetland, characterized in that: The vertical flow artificial wetland comprises: A packing bed comprising a first packing layer (110), a second packing layer (120), and a third packing layer (130) sequentially arranged along a flow direction of water in the packing bed; A water distribution pipe (210) is provided on the first packing layer (110); along the water flow direction of the water distribution pipe (210), the water distribution pipe (210) is provided with a plurality of water distribution holes (211) to introduce sewage into the packing bed; A water collecting pipe (310) is provided in the third packing layer (130), and is provided with a plurality of water collecting holes (311) along the water flow direction of the water collecting pipe (310) to collect the treated water after being treated by the packing bed and to lead the treated water out of the packing bed; Along the water flow direction of the water distribution pipe (210), the vertical distance between the water distribution pipe (210) and the water collecting pipe (310) gradually decreases; Along the water flow direction of the water distribution pipe (210), the apertures of the plurality of water distribution holes (211) increase in sequence; and / or, along the water flow direction of the water collection pipe (310), the apertures of the plurality of water collection holes (311) increase in sequence; Along the water flow direction of the water distribution pipe (210), the density of the plurality of water distribution holes (211) decreases sequentially; and / or, along the water flow direction of the water collection pipe (310), the density of the plurality of water collection holes (311) decreases sequentially; The extension direction of the water distribution pipe (210) forms an angle with the direction of gravity, and the angle is an acute angle; The elevation of the front end of the water distribution pipe (210) is higher than the elevation of the end of the water distribution pipe (210); The vertical flow artificial wetland includes a downflow vertical flow artificial wetland and an upflow vertical flow artificial wetland; in the downflow vertical flow artificial wetland, the front elevation of the water collecting pipe (310) is lower than the end elevation of the water collecting pipe (310); in the upflow vertical flow artificial wetland, the front elevation of the water collecting pipe (310) is higher than the end elevation of the water collecting pipe (310).

2. The vertical flow artificial wetland according to claim 1, characterized in that: The flow direction of the water body in the packing bed forms an angle with the extension direction of the water collecting pipe (310), and the angle is an obtuse angle.

3. The vertical flow artificial wetland according to claim 1, characterized in that: The filler particle size of the first filler layer (110) is larger than the filler particle size of the second filler layer (120), and smaller than the filler particle size of the third filler layer (130).

4. The vertical flow artificial wetland according to claim 1, characterized in that: Along the water flow direction of the water distribution pipe (210), the filler porosity of the first filler layer (110) gradually decreases; and / or, Along the water flow direction of the water distribution pipe (210), the filler porosity of the second filler layer (120) gradually decreases; and / or, Along the water flow direction of the water distribution pipe (210), the filler porosity of the third filler layer (130) gradually decreases.

5. The vertical flow artificial wetland according to claim 1, characterized in that: Along the water flow direction of the water distribution pipe (210), the filler particle size of the first filler layer (110) gradually decreases; and / or, Along the water flow direction of the water distribution pipe (210), the filler particle size of the second filler layer (120) gradually decreases; and / or, Along the water flow direction of the water distribution pipe (210), the filler particle size of the third filler layer (130) gradually decreases.

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