Efficient constructed wetland system and its ecological purification method

Abstract

The present invention provides an efficient constructed wetland system and its ecological purification method, belonging to the technical field of constructed wetlands. A vertical subsurface flow wetland is arranged inside, and a horizontal subsurface flow wetland is arranged on the outer ring of the vertical subsurface flow wetland. The vertical subsurface flow wetland uses a central water inlet pipe for water inlet. Sewage enters from the central water inlet pipe, is distributed through symmetrically cross - arranged water distribution pipes and converges through the annular water channel of the vertical flow wetland, and then reaches the annular water channel of the horizontal flow wetland. Compared with the traditional rectangular wetland, the land utilization rate is higher, achieving the technical effects of more uniform water distribution, more stable operation of the wetland system, and higher sewage treatment efficiency.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection technologies, and more specifically, to an efficient constructed wetland system and an ecological purification method thereof. Background Art

[0002] With the development of urban scale and social economy, urban river channels have been polluted to varying degrees. Some river channels have problems such as being extremely turbid, having less clear water and more medium-quality water, eutrophication causing some aquatic organisms to be difficult to survive, and even having a fishy smell. Even if it takes a long time and a large amount of money to improve the scenery along the riverbank, the scenery around the river channel will ultimately be affected by the sewage in the river channel.

[0003] In recent years, water pollution control technologies have gradually shifted from the original centralized treatment to decentralized and in-situ treatment. Its characteristic is that the research on ecological process technologies has been booming in recent years. In ecological process technologies, the use of constructed wetlands gives full play to the potential of each component in the wetland system, achieving double benefits of environment and economy, and becoming a cheap alternative to traditional sewage treatment processes in many fields. Applying it to fields such as source control, in-situ ecological restoration, and watershed pollution control has achieved good results.

[0004] Although traditional constructed wetland sewage treatment technologies have advantages such as small investment, simple operation, low energy consumption, and simple operation and maintenance management, they also have a series of problems such as large land occupation, easy clogging, uneven water distribution, and low nitrogen removal rate.

[0005] The prior art discloses a method for treating domestic sewage by a stacked vertical flow-horizontal subsurface flow combined wetland (application number 201210015622.2), which adopts a stacked vertical subsurface flow and horizontal subsurface flow combined wetland system. The subsurface flow wetland is composed of multiple independent filter bed modules nested up and down. Although the purification efficiency is improved and the effect of preventing clogging is achieved, there are still problems such as a large structural drop between the stacked wetlands, limited application range; if processed manually, it will inevitably increase the investment cost and affect the surrounding environment. It also discloses a stacked vertical flow low-oxygen constructed wetland water treatment device (application number: 201420012251.7), which adopts a stacked structure to reduce the land area of the wetland and realizes the linkage between the upper and lower layer wetlands by configuring two-stage lift pumps, reflux pumps, and aerators; however, it still has the disadvantages of high operating energy consumption, complex structure, and general phosphorus removal effect.

[0006] There is an urgent need for an ecological purification method and system for an efficient constructed wetland with better phosphorus removal effect on the basis of small land occupation. Summary of the Invention

[0007] In view of the above problems, the object of the present invention is to provide an efficient constructed wetland system and its ecological purification method to solve the problems of low sewage treatment efficiency of existing constructed wetlands and large land occupation area of constructed wetlands.

[0008] The present invention provides an ecological purification method for an efficient constructed wetland. The method includes that sewage enters a first-level vertical subsurface flow wetland arranged at the center of a first-level ecological purification unit from a first-level central water inlet pipe; wherein, the first-level ecological purification unit includes a first-level vertical subsurface flow wetland and a first-level horizontal subsurface flow wetland arranged on the outer ring of the first-level vertical subsurface flow wetland;

[0009] After water distribution through symmetrically cross-arranged first-level water distribution pipes and water collection through the annular water channel of the first-level vertical flow wetland, the first-level preliminarily purified sewage is obtained;

[0010] The first-level preliminarily purified sewage overflows to the annular water channel of the first-level horizontal subsurface flow wetland in the first-level horizontal subsurface flow wetland through a first-level overflow weir;

[0011] After ecological purification through the annular channel of the first-level horizontal subsurface flow wetland, the first-level purified water is obtained.

[0012] Furthermore, the preferred method further includes that

[0013] The first-level purified water enters a second-level ecological purification unit arranged at the outer ring of the first-level ecological purification unit from a second-level water inlet pipe; wherein, the second-level ecological purification unit includes a second-level vertical subsurface flow wetland and a second-level horizontal subsurface flow wetland arranged on the outer ring of the second-level vertical subsurface flow wetland; the outlet pipe of the horizontal subsurface flow wetland of the first-level ecological purification unit is connected to the central water inlet pipe of the vertical subsurface flow wetland of the second-level ecological purification unit;

[0014] After water distribution through symmetrically cross-arranged second-level water distribution pipes and water collection through the annular water channel of the second-level vertical flow wetland, the second-level preliminarily purified sewage is obtained;

[0015] The second-level preliminarily purified sewage overflows to the annular water channel of the second-level horizontal subsurface flow wetland in the second-level horizontal subsurface flow wetland through a second-level overflow weir;

[0016] After ecological purification through the annular channel of the second-level horizontal subsurface flow wetland, the second-level purified water is obtained.

[0017] Furthermore, the preferred method further includes that

[0018] Sewage alternately enters the first-level ecological purification unit I and the first-level ecological purification unit II in parallel for ecological purification to obtain purified water; wherein,

[0019] Each level of ecological purification unit includes at least two ecological purification units in parallel, and each ecological purification unit includes a vertical subsurface flow wetland and a horizontal subsurface flow wetland annularly arranged on the outer ring of the vertical subsurface flow wetland.

[0020] Furthermore, the preferred method further includes

[0021] aerating the vertical flow wetland vent pipe and the horizontal flow wetland vent pipe at a preset time frequency to increase the oxygen content in the vertical subsurface flow wetland and the horizontal subsurface flow wetland; wherein, the vertical flow wetland vent pipe is arranged in the vertical subsurface flow wetland, and the horizontal flow wetland vent pipe is arranged in the horizontal subsurface flow wetland.

[0022] Furthermore, the preferred method includes that both the first-level vertical subsurface flow wetland and the first-level horizontal subsurface flow wetland include a substrate layer, a covering layer and a plant layer arranged in sequence from bottom to top;

[0023] The substrate layer is one or more of limestone, volcanic rock, zeolite, shale, ceramsite and slag;

[0024] The covering layer is planting soil or sandy soil.

[0025] Furthermore, the preferred method includes that the plant layer is one or more of reed, cattail, calamus, canna, thalia dealbata, softstem bulrush, water dropwort, rush, wild rice stem and ryegrass.

[0026] Furthermore, the preferred method includes that a double-sided triangular overflow weir is arranged at the annular water channel of the first-level vertical flow wetland, and the height difference between the water inlet weir and the water outlet weir of the double-sided triangular overflow weir is 10 - 50 cm; the width of the weir trough is 20 - 80 cm; the water depth in the weir trough is 5 - 20 cm.

[0027] Furthermore, the preferred method includes that a partition plate separating the water inlet channel and the water outlet channel is arranged in the first-level horizontal subsurface flow wetland; the partition plate is arranged in a ring shape.

[0028] Furthermore, the preferred method includes that the distance between the bottom end of the partition plate and the bottom of the pool is 20 - 50 cm; the partition plate is made of steel slag bricks.

[0029] The present invention further includes an efficient constructed wetland system for implementing the ecological purification method of the above-mentioned efficient constructed wetland. The system includes:

[0030] The first-level vertical subsurface flow wetland is arranged at the center of the circle, and the first-level horizontal subsurface flow wetland is arranged on the outer ring of the first-level vertical subsurface flow wetland;

[0031] The first-level vertical subsurface flow wetland includes a first-level central water inlet pipe, a first-level vertical flow wetland annular water channel and a first-level water distribution pipe arranged between the first-level central water inlet pipe and the first-level vertical flow wetland annular water channel;

[0032] The first-level horizontal subsurface flow wetland includes a first-level horizontal flow wetland annular water channel; Sewage enters from the first-level central water inlet pipe, passes through the first-level water distribution pipe and the first-level vertical flow wetland annular water channel to reach the first-level horizontal flow wetland annular water channel.

[0033] The efficient constructed wetland system and its ecological purification method provided by the present invention, as a practical and efficient sewage treatment and reuse technology, have the following beneficial effects:

[0034] 1. The entire constructed wetland system adopts a circular structure. By arranging a vertical subsurface flow wetland inside, and a horizontal subsurface flow wetland is arranged in the outer ring of the vertical subsurface flow wetland; among them, the vertical subsurface flow wetland uses a central water inlet pipe for water inlet. Sewage enters from the central water inlet pipe, and after being distributed by symmetrically cross - arranged water distribution pipes and converging through the annular water channel of the vertical flow wetland, it reaches the annular water channel of the horizontal flow wetland; compared with the traditional rectangular wetland, the land utilization rate is higher; the water distribution is more uniform, the wetland system operates more stably, and the sewage treatment efficiency is higher;

[0035] 2. The multi - stage setting of the vertical subsurface flow wetland and the horizontal subsurface flow wetland makes the water passing area larger, has strong adaptability to water quality and water volume changes, and has a wide application range; when the pollution concentration of the influent water quality is relatively high or the effluent water quality requirements are increased, the number of ecological purification stages can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] By referring to the following description in conjunction with the drawings and the content of the claims, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become clearer and easier to understand. In the drawings:

[0037] Figure 1 is a schematic structural diagram of the efficient constructed wetland system according to an embodiment of the present invention;

[0038] Figure 2 is a schematic cross - sectional view of the efficient constructed wetland system according to an embodiment of the present invention.

[0039] In all the drawings, the same reference numerals indicate similar or corresponding features or functions.

[0040] In the figure: 1. Vertical subsurface flow wetland; 2. Horizontal subsurface flow wetland; 3. Plant layer; 4. Cover layer; 5. Substrate layer; 11. Vent pipe of vertical flow wetland; 12. Annular water channel of vertical flow wetland; 13. Water distribution pipe; 14. Central water inlet pipe; 21. Vent pipe of horizontal flow wetland; 22. Annular water channel of horizontal flow wetland; 23. Partition board. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The following will describe the specific embodiments of the present invention in detail with reference to the drawings.

[0042] In view of the problems of low sewage treatment efficiency and large floor area of the existing constructed wetlands, the present invention provides a solution by arranging a vertical subsurface flow wetland inside, with a horizontal subsurface flow wetland arranged in the outer ring of the vertical subsurface flow wetland. The vertical subsurface flow wetland is fed with sewage through a central inlet pipe. The sewage enters from the central inlet pipe, is distributed through symmetrically cross - arranged water distribution pipes and collected by the annular water channel of the vertical flow wetland, and then reaches the annular water channel of the horizontal flow wetland. Compared with the traditional rectangular wetland, it has a higher land utilization rate, more uniform water distribution, more stable operation of the wetland system, and higher sewage treatment efficiency. The multi - stage arrangement of the vertical subsurface flow wetland and the horizontal subsurface flow wetland enables an increase in the number of ecological purification stages when the influent water quality pollution concentration is high or the effluent water quality requirement is increased, resulting in a larger water passing area, strong adaptability to water quality and quantity changes, and a wide application range.

[0043] The present invention discloses an ecological purification method for an efficient constructed wetland, which includes the following steps

[0044] S110. Sewage enters the first - stage vertical subsurface flow wetland located at the center of the first - stage ecological purification unit from the first - stage central inlet pipe. The first - stage ecological purification unit includes a first - stage vertical subsurface flow wetland and a first - stage horizontal subsurface flow wetland arranged in the outer ring of the first - stage vertical subsurface flow wetland. S120. After water distribution through symmetrically cross - arranged first - stage water distribution pipes and water collection by the annular water channel of the first - stage vertical flow wetland, the first - stage preliminarily purified sewage is obtained. A double - sided triangular overflow weir is arranged at the annular water channel of the first - stage vertical flow wetland. The height difference between the inlet weir and the outlet weir of the double - sided triangular overflow weir is 10 - 50 cm; the width of the weir trough is 20 - 80 cm; the water depth in the weir trough is 5 - 20 cm. Both the first - stage vertical subsurface flow wetland and the first - stage horizontal subsurface flow wetland include a substrate layer, a covering layer, and a plant layer arranged in sequence from bottom to top. The substrate layer is one or more of limestone, volcanic rock, zeolite, shale, ceramsite, and slag. The covering layer is planting soil or sandy soil. The plant layer is one or more of reed, cattail, calamus, canna, thalia dealbata, softstem bulrush, water dropwort, rush, wild rice stem, and ryegrass. S130. The first - stage preliminarily purified sewage overflows through the first - stage overflow weir into the annular water channel of the first - stage horizontal subsurface flow wetland of the first - stage horizontal flow wetland. S140. After ecological purification by the annular water channel of the first - stage horizontal subsurface flow wetland, the first - stage purified water is obtained. A partition plate that separates the inlet channel and the outlet channel at intervals is arranged in the first - stage horizontal subsurface flow wetland. The partition plate is arranged in a ring shape. The distance between the bottom end of the partition plate and the bottom of the pool is 20 - 50 cm. The partition plate is made of steel slag bricks.

[0045] As an improvement of this embodiment, the multi-level ecological purification units can be arranged in a circular nested manner. The specific implementation method includes: S210, the water purified at the first level enters the second-level ecological purification unit arranged at the outer ring of the first-level ecological purification unit through the second-level water inlet pipe; wherein, the second-level ecological purification unit includes a second-level vertical subsurface flow wetland and a second-level horizontal subsurface flow wetland arranged at the outer ring of the second-level vertical subsurface flow wetland; the outlet pipe of the horizontal subsurface flow wetland of the first-level ecological purification unit is connected to the central water inlet pipe of the vertical subsurface flow wetland of the second-level ecological purification unit; S220, after water distribution through the symmetrically cross-arranged second-level water distribution pipes and water collection through the second-level vertical flow wetland annular water channel, the sewage after the second-level primary purification is obtained; S230, the sewage after the second-level primary purification overflows to the second-level horizontal flow wetland annular water channel of the second-level horizontal subsurface flow wetland through the second-level overflow weir; S240, after ecological purification through the second-level horizontal flow wetland annular water channel, the water after the second-level purification is obtained.

[0046] In a specific embodiment, multiple ecological purification units can also be arranged in parallel; specifically, the sewage alternately enters the first-level ecological purification unit I and the first-level ecological purification unit II arranged in parallel for ecological purification to obtain the purified water; wherein, each level of ecological purification unit includes at least two ecological purification units arranged in parallel, and each ecological purification unit includes a vertical subsurface flow wetland and a horizontal subsurface flow wetland arranged in a ring at the outer ring of the vertical subsurface flow wetland.

[0047] Furthermore, the preferred method also includes ventilating the vertical flow wetland vent pipe and the horizontal flow wetland vent pipe at a preset time frequency to increase the oxygen content in the vertical subsurface flow wetland and the horizontal subsurface flow wetland; wherein, the vertical flow wetland vent pipe is arranged in the vertical subsurface flow wetland, and the horizontal flow wetland vent pipe is arranged in the horizontal subsurface flow wetland.

[0048] To illustrate the high-efficiency constructed wetland system provided by the present invention, Figure 1 and Figure 2 the constructed wetland system is described as a whole; wherein, Figure 1 shows the structure of the high-efficiency constructed wetland system according to the embodiment of the present invention; Figure 2 is Figure 1 a cross-sectional view of.

[0049] As Figure 1 shown, the high-efficiency constructed wetland system in this embodiment only includes a single-level ecological purification unit and there is no ecological purification unit arranged in parallel with each other. Therefore, the first-level vertical subsurface flow wetland is the vertical subsurface flow wetland 1; the first-level horizontal subsurface flow wetland is the horizontal subsurface flow wetland 2; the first-level central water inlet pipe is the central water inlet pipe 14, the first-level vertical flow wetland annular water channel is the vertical flow wetland annular water channel 12, the first-level water distribution pipe is the water distribution pipe 13, and the first-level horizontal flow wetland annular water channel is the horizontal flow wetland annular water channel 22.

[0050] The efficient constructed wetland system provided by the present invention includes a vertically subsurface flow wetland 1 and a horizontally subsurface flow wetland 2 arranged in a ring shape; the vertically subsurface flow wetland 1 is arranged at the center of the circle, and the horizontally subsurface flow wetland 2 is arranged on the outer ring of the vertically subsurface flow wetland; the vertically subsurface flow wetland 1 includes a central water inlet pipe 14, a vertically flowing wetland annular water channel 12, and a water distribution pipe 13 arranged between the central water inlet pipe 14 and the vertically flowing wetland annular water channel 12; the horizontally subsurface flow wetland includes a horizontally flowing wetland annular water channel 22; sewage enters from the central water inlet pipe 14, passes through the water distribution pipe 13 and the vertically flowing wetland annular water channel 12, and reaches the horizontally flowing wetland annular water channel 22 through the overflow weir.

[0051] Specifically, both the vertically subsurface flow wetland 1 and the horizontally subsurface flow wetland 2 include a substrate layer 5, a covering layer 4, and a plant layer 3 arranged in sequence from bottom to top; the substrate layer 5 is one or more of limestone, volcanic rock, zeolite, shale, ceramsite, and slag, and the wetland substrate is selected as a non-toxic and harmless substance with certain mechanical strength, good chemical stability, good denitrification and phosphorus removal effects, and can be locally sourced. The filler particle size is 8 - 25 mm, and the main filler thickness is 0.8 - 1.5 m; the covering layer 4 is planting soil or sandy soil, and the laying thickness is 10 cm - 30 cm. The plant layer 3 is to plant wetland plants on the covering layer, and the wetland plants are selected as native plants with strong pollution resistance, strong decontamination ability, developed root systems, strong reoxygenation ability, and certain economic ornamental value; it can be but not limited to one or more of reed, cattail, calamus, canna, thalia dealbata, scirpus validus, watercress, juncus effusus, wild rice stem, and ryegrass.

[0052] It should be noted that the water distribution pipe 13 is a water pipe with through holes provided on its outer wall. By the number and arrangement position of the water distribution pipes, not only can the water distribution uniformity be improved, but also the water flow direction can be changed. In the specific implementation process, the water distribution pipes 13 are arranged in an array in the vertically subsurface flow wetland. That is to say, the water distribution pipes are laid in multiple layers and multiple roots along the longitudinal direction of the wetland. As Figure 2 shown, the way of laying 2 - layer and 4 - root cross - laid water distribution pipes can save the laying cost on the basis of ensuring uniform water distribution; through the water distribution pipes, the water flow in the wetland flows and mixes along the arrow direction, so as to achieve the effect of removing pollutants in the water through the combined action of the substrate layer, the plant layer, and the microorganisms in the water.

[0053] That is to say, the vertical subsurface flow wetland 1 is located in the middle of the constructed wetland system. The central water inlet pipe 14 is used for water inlet, and the multi-layer water distribution pipes 13 are used for water distribution. Finally, the water enters the vertical flow wetland annular water channel 12 around the wetland for collecting the effluent. The effluent of the vertical subsurface flow wetland 1 enters the horizontal subsurface flow wetland 2 in the outer ring. The whole wetland system adopts a circular structure, with fewer corners compared with a rectangular wetland, thus improving the land utilization rate. The vertical subsurface flow wetland uses the central water inlet pipe for water inlet, and the water distribution pipes inside are symmetrically and cross-arranged for water distribution, and the annular water channel collects the water; the horizontal subsurface flow uses the annular water channel overflow weir for water distribution, and the annular water channel collects the water. Compared with the traditional rectangular wetland, the hydraulic conditions of the constructed wetland system of the present invention are more favorable, the water distribution is more uniform, and the risk of wetland blockage can be reduced; moreover, the operation is more stable, which is beneficial to the combined action of the substrate, plants, and microorganisms in the water to remove more pollutants.

[0054] In the specific implementation process, in order to improve the purification efficiency, it is set according to the actual sewage treatment requirements. The incoming water entering the constructed wetland system is divided into two parts and enters the vertical subsurface flow wetland and the horizontal subsurface flow wetland according to a water volume ratio of 5:1 to 10:1.

[0055] As Figure 2 shown, the water treated by the vertical subsurface flow wetland 1 is evenly led out through the overflow weir and enters the horizontal subsurface flow wetland 2. In the horizontal subsurface flow wetland 2, the water flows along the arrow direction around the partition board. Among them, a partition board 23 that separates the water inlet channel and the water outlet channel is arranged in the horizontal subsurface flow wetland 2; the partition board 23 is arranged in a ring shape.

[0056] Specifically, a double-sided triangular overflow weir is arranged at the outer edge of the vertical flow wetland annular water channel 12. The height difference between the water inlet weir and the water outlet weir of the double-sided triangular overflow weir is 10 - 50 cm; the width of the weir trough is 20 - 80 cm; the water depth in the weir trough is 5 - 20 cm. The elevation of the top of the triangular overflow weir is lower than the bottom of the covering layer 4 of the vertical subsurface flow wetland 1. The water flow can not only distribute the water evenly and observe the effluent water quality through the triangular overflow weir, but also increase the dissolved oxygen content during the water flow drop process.

[0057] It should be noted that at the connection between the triangular overflow weir and the substrate layer, in order to prevent particulate matter from entering the water channel, it is wrapped with a non-toxic, corrosion-resistant, anti-aging, and water-permeable mesh cloth (such as geotextile), and the aperture of the mesh cloth should be smaller than the particle size of the substrate filler. In the specific implementation process, the outer annular water channel of the horizontal subsurface flow wetland uses a single-sided triangular overflow weir, and the relevant design parameters of the overflow weir are the same as those of the vertical subsurface flow wetland.

[0058] In a specific embodiment, the distance between the bottom end of the partition plate 23 and the bottom of the pond is 20 - 50 cm; the partition plate 23 is made of steel slag bricks. The partition plate is arranged between the water inlet channel and the water outlet channel, and can be, but is not limited to, arranged in a circular or diagonal direction, either continuously or at intervals. Among them, the partition plate can be, but is not limited to, a flat plate or a folded plate. It should be noted that the arrangement of the partition plate extends the hydraulic path of the water flow and prolongs the treatment time of the sewage in the wetland. The partition plate is made of steel slag bricks. Steel slag is the waste residue generated in the smelting industry, containing a large amount of active ions such as iron, magnesium, and calcium, which can adsorb and replace phosphorus ions in the water body. The partition plate can be a movable wall, and the steel slag bricks can be replaced regularly according to the operation needs of the wetland to remove the enriched phosphorus element, reduce the risk of clogging of the filler, and extend the service life of the wetland. In the specific implementation process, the partition plate can be a circular flat partition plate (such as Figure 1 as shown). By setting the partition plate, the water flow can be made to flow along a fixed path, increasing the residence time, changing the flow pattern of the water body, and achieving the technical effects of saving land and improving the pollutant removal efficiency. In addition to the circular arrangement, the partition plate can also be set as a flat plate or a corrugated plate with different heights according to the actual application scenario, which is not specifically limited here.

[0059] In an embodiment, intermittent aeration pipelines are provided in both the vertical subsurface flow wetland 1 and the horizontal subsurface flow wetland 2; specifically, a vertical flow wetland aeration pipe 11 is provided in the vertical subsurface flow wetland 1; a horizontal flow wetland aeration pipe 21 is provided in the horizontal subsurface flow wetland 2. Specifically, by providing intermittent aeration pipelines inside both the vertical subsurface flow wetland and the horizontal subsurface flow wetland, the oxygenation capacity of the wetland can be further increased, and organic pollutants in the water can be removed. Among them, the aeration pipes are located at the end of the water distribution pipe in the vertical subsurface flow wetland and inside the horizontal subsurface flow wetland, and are evenly arranged. The aeration pipelines are 20 - 50 cm away from the bottom of the pond and extend vertically upward 5 - 30 cm above the surface of the wetland filler. An aeration cap is provided at the top of the aeration pipe. The aeration pipes are arranged inside the horizontal subsurface flow to increase the oxygen content in the wetland. During intermittent operation, the wetland can be re-oxygenated more quickly.

[0060] In a specific embodiment, it includes at least two levels of nested ecological purification units. Each level of ecological purification unit includes a vertically arranged vertical subsurface flow wetland 1 and a horizontally arranged horizontal subsurface flow wetland 2 that are circularly arranged; the outlet pipe of the horizontal subsurface flow wetland 2 of the first-level ecological purification unit is connected to the central inlet pipe 14 of the vertical subsurface flow wetland 1 of the second-level ecological purification unit. It should be noted that the specific number of levels of the ecological purification unit is set according to the actual site area and the sewage treatment requirements; by nesting multiple levels of ecological purification units, the degree of sewage purification can be further improved, which is applicable to scenarios with a relatively high pollution concentration of the influent water quality or a relatively high requirement for the effluent water quality.

[0061] In a specific embodiment, it includes at least two levels of ecologically purified units connected in parallel. Each level of the ecologically purified unit includes a vertically subsurface flow wetland and a horizontally subsurface flow wetland arranged in a ring shape. It should be noted that the specific number of levels of the ecologically purified unit is set according to the actual site area and sewage treatment requirements; the multi-level setting of the vertically subsurface flow wetland and the horizontally subsurface flow wetland results in a larger water passing area, strong adaptability to water quality and water volume changes, and a wide application range; it is applicable to scenarios with a large sewage volume. It should be noted that when the constructed wetland system adopts two or more groups of ecologically purified units arranged in parallel, in order to reduce the clogging of the constructed wetland and extend the service life of the constructed wetland system, the multiple ecologically purified units operate intermittently in a tidal flow manner; this is achieved by alternating aerobic and anaerobic conditions in the wetland, strengthening nitrification and denitrification reactions, and achieving the technical effect of improving the nitrogen removal rate.

[0062] In the specific implementation process, the sewage filtered by the constructed wetland is discharged into the stabilization pond through the water outlet of the subsurface flow wetland of the last-level constructed wetland. In the stabilization pond, the sewage filtered by the constructed wetland system is further purified, and the sewage purified by the stabilization pond is discharged into the downstream river through the collecting well.

[0063] As can be seen from the above, by internally arranging a vertically subsurface flow wetland, and the horizontally subsurface flow wetland is arranged on the outer ring of the vertically subsurface flow wetland; the vertically subsurface flow wetland is fed water through a central water inlet pipe. The sewage enters from the central water inlet pipe, and after being distributed by the symmetrically cross-arranged water distribution pipes and converging through the annular water channel of the vertical flow wetland, it reaches the annular water channel of the horizontal flow wetland; compared with the traditional rectangular wetland, the ground utilization rate is higher; the water distribution is more uniform, the wetland system operates more stably, and the sewage treatment efficiency is higher; the multi-level setting of the vertically subsurface flow wetland and the horizontally subsurface flow wetland results in a larger water passing area, strong adaptability to water quality and water volume changes, and a wide application range; when the pollution concentration of the influent water quality is relatively high or the effluent water quality requirements are increased, the number of levels of ecological purification can be increased.

[0064] As described above, the efficient constructed wetland system according to the present invention has been described by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various improvements can be made to the above-mentioned efficient constructed wetland system proposed by the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the appended claims.

Claims

1. An ecological purification method for an efficient constructed wetland, the method comprising: Sewage enters a first-stage vertical subsurface flow wetland arranged at the center of the first-stage ecological purification unit through a first-stage central inlet pipe; wherein, The primary ecological purification unit includes a primary vertical subsurface flow wetland and a primary horizontal subsurface flow wetland arranged on the outer ring of the primary vertical subsurface flow wetland; the primary vertical subsurface flow wetland includes a substrate layer, a covering layer, and a plant layer arranged in sequence from bottom to top; After water distribution through symmetrically cross - arranged primary water distribution pipes and water collection through the annular water channel of the primary vertical flow wetland, the primary pre - purified sewage is obtained; among them, the water flow and mixing within the wetland are realized through the water distribution pipes, so as to achieve the effect of removing pollutants in water through the combined action of the substrate layer, the plant layer, and the microorganisms in the water; the water distribution pipes are laid in multiple layers and multiple roots along the longitudinal direction of the wetland; The primary pre - purified sewage overflows through a primary overflow weir into the annular water channel of the primary horizontal subsurface flow wetland of the primary horizontal subsurface flow wetland; After the ecological purification of the annular channel of the primary horizontal subsurface flow wetland, the primary purified water is obtained; The primary purified water enters the secondary ecological purification unit arranged at the outer ring of the primary ecological purification unit from the secondary water inlet pipe; among them, the secondary ecological purification unit includes a secondary vertical subsurface flow wetland and a secondary horizontal subsurface flow wetland arranged on the outer ring of the secondary vertical subsurface flow wetland; the outlet pipe of the horizontal subsurface flow wetland of the first - level ecological purification unit is connected to the central water inlet pipe of the vertical subsurface flow wetland of the second - level ecological purification unit; After water distribution through symmetrically cross - arranged secondary water distribution pipes and water collection through the annular water channel of the secondary vertical flow wetland, the secondary pre - purified sewage is obtained; The secondary pre - purified sewage overflows through a secondary overflow weir into the annular water channel of the secondary horizontal subsurface flow wetland of the secondary horizontal subsurface flow wetland; After the ecological purification of the annular channel of the secondary horizontal subsurface flow wetland, the secondary purified water is obtained.

2. The ecological purification method for an efficient constructed wetland according to claim 1, characterized in that: The method further includes, The sewage alternately enters the parallel - connected primary ecological purification unit I and primary ecological purification unit II for ecological purification to obtain the purified water; among them, Each level of ecological purification unit includes at least two parallel - connected ecological purification units, and each ecological purification unit includes a vertical subsurface flow wetland and a horizontal subsurface flow wetland annularly arranged on the outer ring of the vertical subsurface flow wetland.

3. The ecological purification method for an efficient constructed wetland according to claim 1, characterized in that: It further includes, The vertical flow wetland vent pipe and the horizontal flow wetland vent pipe are ventilated according to a preset time frequency to increase the oxygen content in the vertical subsurface flow wetland and the horizontal subsurface flow wetland; among them, the vertical flow wetland vent pipe is arranged in the vertical subsurface flow wetland, and the horizontal flow wetland vent pipe is arranged in the horizontal subsurface flow wetland.

4. The ecological purification method for an efficient constructed wetland according to claim 1, characterized in that: Each primary horizontal subsurface flow wetland includes a substrate layer, a covering layer, and a plant layer arranged in sequence from bottom to top; The substrate layer is one or more of limestone, volcanic rock, zeolite, shale, ceramsite, and slag; The covering layer is planting soil or sandy soil.

5. The ecological purification method for an efficient constructed wetland according to claim 4, characterized in that: The plant layer is one or more of reed, cattail, calamus, canna, thalia dealbata, scirpus validus, watercress, juncus effusus, wild rice stem, and ryegrass.

6. The ecological purification method for an efficient constructed wetland according to claim 1, characterized in that: A double - sided triangular overflow weir is arranged at the annular water channel of the primary vertical flow wetland, and the height difference between the water inlet weir and the water outlet weir of the double - sided triangular overflow weir is 10 - 50 cm; the width of the weir trough is 20 - 80 cm; the water depth in the weir trough is 5 - 20 cm.

7. The ecological purification method for an efficient constructed wetland according to claim 1, characterized in that: A partition for separating the water inlet channel and the water outlet channel is arranged in the primary horizontal subsurface flow wetland; the partition is arranged in a ring shape.

8. The ecological purification method for an efficient constructed wetland according to claim 7, characterized in that: The distance between the bottom end of the partition plate and the bottom of the pool is 20 - 50 cm; the partition plate is made of steel slag bricks.

9. An efficient constructed wetland system, characterized in that: Implement the ecological purification method of the high-efficiency constructed wetland according to claim 1, the system includes: The first-level vertical subsurface flow wetland is arranged at the center of the circle, and the first-level horizontal subsurface flow wetland is arranged on the outer ring of the first-level vertical subsurface flow wetland; The first-level vertical subsurface flow wetland includes a first-level central water inlet pipe, a first-level vertical flow wetland annular water channel, and a first-level water distribution pipe arranged between the first-level central water inlet pipe and the first-level vertical flow wetland annular water channel; The first-level horizontal subsurface flow wetland includes a first-level horizontal flow wetland annular water channel; the sewage enters from the first-level central water inlet pipe, passes through the first-level water distribution pipe and the first-level vertical flow wetland annular water channel to reach the first-level horizontal flow wetland annular water channel.

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