River sewage purification system and method based on plant population

Abstract

The invention discloses a river sewage purification system and method based on plant populations, a plant buffer area constructed at a river entrance intercepts a water body, a gravel layer is laid at the bottoms of a gentle slope and a still water area, and aquatic plants are planted on the still water area; the water diversion pipe is vertically arranged at the junction of the plant buffer area and the wetland purification area, the permeation pipes are communicated with the bottom of the water diversion pipe and are arranged along the wetland purification area, permeation holes are formed in the tops of the permeation pipes, and a coarse gravel layer, a water diversion gravel layer and a fine gravel layer are sequentially laid above the permeation pipes from bottom to top. The plant buffer area intercepts and absorbs part of pollutants by using root systems, stems and leaves of plants, slows down the water flow speed and enables suspended solids to settle, the special hierarchical structure of the coarse gravel layer, the diversion gravel layer and the fine gravel layer is beneficial to filtering and adsorbing the pollutants, aquatic plants are planted on the still water area to promote decomposition and conversion of organic matters, and the water quality is improved. The purification effect of the water body is further improved, and efficient purification of the river sewage is realized.

Description

Technical Field

[0001] The invention relates to the technical field of river management, and in particular to a river sewage purification system and method based on plant populations. Background Art

[0002] With the rapid acceleration of industrialization and urbanization around the world, river pollution has become increasingly serious and has become an environmental challenge that cannot be ignored. In particular, those industrial wastewater and domestic sewage that have not been properly treated are discharged into rivers at will, posing an unprecedented threat to the fragile river ecosystem, not only destroying the habitat of aquatic organisms, but also affecting the water safety of human beings themselves.

[0003] For a long time, traditional means of dealing with river pollution have mainly relied on technical means such as physical filtration, chemical precipitation and biological treatment. Although these technologies can effectively remove pollutants in water to a certain extent, they generally face many problems such as high operating costs, high energy consumption and possible secondary pollution. Plants in nature play a vital role in maintaining ecological balance with their unique purification ability. With their powerful root absorption, leaf transformation and biodegradation mechanisms, they can effectively remove harmful substances from water bodies and restore the clarity and vitality of water bodies. Inspired by this, researchers began to explore the use of diverse plant populations to build innovative river sewage purification systems, aiming to imitate and optimize nature's self-purification process.

[0004] However, most of the currently implemented plant purification systems are limited to the application of a single plant species, and this approach often ignores the possible synergistic effects between different plants. In fact, different plants can promote each other through complex mechanisms such as root secretions and microbial symbiosis to form a more powerful purification network. Therefore, the purification efficiency and effect of the purification system that only relies on a single plant species are often unsatisfactory and difficult to fully meet the growing environmental protection needs. It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a river sewage purification system and method based on plant populations, so as to solve the problem that the purification effect of a single plant species in the prior art is unsatisfactory.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a river sewage purification system based on plant populations, comprising a plant buffer zone, a wetland purification zone, a slowdown slope and a still water zone constructed in sequence along the river channel; it also comprises a gravel layer and aquatic plants; the plant buffer zone constructed at the river entrance intercepts the water body, and a gravel layer is laid at the bottom of the slowdown slope and the still water zone, and aquatic plants are planted on the still water zone; the wetland purification zone comprises a water diversion pipe, an infiltration pipe, a fine gravel layer, a water diversion gravel layer and a coarse gravel layer; the water diversion pipe is vertically arranged at the junction of the plant buffer zone and the wetland purification zone, the infiltration pipe is connected to the bottom of the water diversion pipe and is arranged along the wetland purification zone, an infiltration hole is opened on the top of the infiltration pipe, and the coarse gravel layer, the water diversion gravel layer and the fine gravel layer are laid in sequence from bottom to top above the infiltration pipe.

[0007] In one embodiment of the present invention, a drainage system is further included, and the static water area penetrates into the ground to form groundwater flow with water veins, and the groundwater flow is led to the main stream of the river through the drainage system.

[0008] The beneficial effect of the above embodiment is that the underground water flow is formed by infiltrating into the ground in the static water area, and the treated water is led back to the main stream of the river by the drainage system, thereby ensuring the circulation and continuous purification capacity of the system and avoiding groundwater pollution.

[0009] In one embodiment of the present invention, the drainage system includes a ground base station and a lift pump. The lift pump is installed in the ground base station, and the water outlet of the lift pump is located on the main stream of the river.

[0010] The beneficial effect of the above embodiment is that the lifting pump installed in the ground base station can efficiently discharge the groundwater flow formed by infiltration to the main stream of the river, ensuring the smooth flow of water and the stable operation of the system.

[0011] In one embodiment of the present invention, ecological revetments are provided on both sides of the plant buffer zone, and the ecological revetments are ecological bases, ecological cages or plant mats.

[0012] The beneficial effect of the above embodiment is that the ecological revetments are set on both sides of the plant buffer zone, which helps to fix the soil, reduce erosion, slow down the water flow, promote the sedimentation of suspended matter, and enhance the stability and ecological benefits of the system.

[0013] In one embodiment of the present invention, the aquatic plants include submerged plants and floating plants, the submerged plants grow in river mud in still water areas, and the floating plants float on the water surface in still water areas.

[0014] The beneficial effect of the above embodiment is that submerged plants grow in the river mud in the still water area, and floating plants float on the water surface. This combination can fully utilize the purification potential of different water layers and improve the overall purification effect.

[0015] In one embodiment of the present invention, a plurality of ecological floating beds are arranged in the still water area, and aquatic plants are planted in the ecological floating beds.

[0016] The beneficial effects of the above embodiment are: a plurality of ecological floating beds are arranged in the still water area to provide a growth matrix for aquatic plants, increase biodiversity, and improve the purification capacity and stability of the system.

[0017] In one embodiment of the present invention, the diameter of the gravel in the fine gravel layer is 35-50 mm, the diameter of the gravel in the coarse gravel layer is 50-80 mm, and the diameter of the gravel in the water diversion gravel layer is greater than the diameter of the gravel in the coarse gravel layer.

[0018] The beneficial effect of the above embodiment is that the provision of the fine gravel layer, the coarse gravel layer and the water diversion gravel layer enables effective filtering and cleaning of pollutants through gravels of different particle sizes, thereby improving the purification efficiency of the system.

[0019] In one embodiment of the present invention, the slowdown slope extends from the wetland purification area to the still water area along the direction of river flow and is inclined, and the slope ratio of the back surface of the slowdown slope is 1:1.

[0020] The beneficial effect of the above embodiment is that the slowdown slope extends from the wetland purification area to the still water area along the direction of the river flow and is inclined, and the slope ratio of the back water surface is 1:1, which helps to further slow down the water flow speed and promote the sedimentation of suspended matter and the removal of pollutants.

[0021] In order to achieve the above-mentioned purpose, the present invention also adopts the following technical scheme: based on plant population and river sewage purification method, using the above-mentioned river sewage purification system based on plant population, including the following steps: S1. Constructing a plant buffer zone; setting a plant buffer zone in the direction of river water inflow, raising the riverbed and planting emergent plants or water-resistant plants on the width of the river, placing ecological revetments on the river bank, fixing the soil, reducing erosion, and at the same time slowing down the water flow speed and promoting the sedimentation of suspended matter; S2. Setting a wetland purification zone; at the junction of the plant buffer zone and the wetland purification zone, the river water is guided into the infiltration pipe through a water diversion pipe, and the sediment is quickly filtered and cleaned through the fine gravel layer, water diversion gravel layer and coarse gravel layer of different sizes on the infiltration pipe; S3. Forming a still water zone; laying a gravel layer on the riverbed in the still water zone, microorganisms attach and form a water body attachment film, and aquatic plants are planted in layers in the still water zone; S4. Lifting and filtering water; the groundwater flow formed by infiltration in the still water zone is discharged to the main stream of the river by a lifting pump.

[0022] In one embodiment of the present invention, in step S3, submerged plants are planted in the river mud in the still water area, and floating plants float on the water surface.

[0023] The beneficial effect of the above embodiment is that the layered planting method fully utilizes the different layers of the water body, thereby improving the purification efficiency and the stability of the ecosystem.

[0024] As described above, the river sewage purification system and method based on plant populations of the present invention have the following beneficial effects: constructing a plant buffer zone at the entrance of the river, using the root system and stems and leaves of the plant to intercept and absorb some pollutants, slowing down the water flow rate, and settling the suspended matter, thereby performing preliminary purification. After passing through the buffer zone, the water body enters the wetland purification area, and the water diversion pipe introduces the water into the infiltration pipe. Above the infiltration pipe, a coarse gravel layer, a water diversion gravel layer and a fine gravel layer are laid in sequence from bottom to top. The special hierarchical structure helps to filter and adsorb pollutants. After passing through the wetland purification area, the water body flows into the slowing slope and the still water area. The flow rate is further slowed down, which is conducive to the deposition of remaining suspended matter and the stabilization of water quality. The gravel layer is laid at the bottom of the still water area, which helps microorganisms to attach and grow, and further remove pollutants. Planting aquatic plants in the still water area further improves the purification effect of the water body by absorbing nutrients in the water and promoting the decomposition and transformation of organic matter through a symbiotic relationship with microorganisms, thereby achieving efficient purification of river sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A cross-sectional view of a river sewage purification system based on plant populations provided by the present invention;

[0027] Figure 2 A schematic diagram of a river sewage purification system based on plant populations provided by the present invention;

[0028] Figure 3 A partial cross-sectional view of a river sewage purification system based on plant populations provided by the present invention;

[0029] Figure 4 A partial schematic diagram of a river sewage purification system based on plant populations provided by the present invention;

[0030] Figure 5 A flow chart of the plant population-based river sewage purification method provided by the present invention.

[0031] Component number description

[0032] 1 Vegetation buffer 9 Fine gravel layer

[0033] 2 Wetland purification area 10 Water diversion gravel layer

[0034] 3 Slowdown slope 11 Coarse gravel layer

[0035] 4 Still water area 12 Groundwater flow

[0036] 5 Gravel layer 13 Drainage system

[0037] 6 Aquatic plants 14 Lifting pump

[0038] 7 Water diversion pipe 15 Ecological revetment

[0039] 8 Infiltration pipe 16 Ecological floating bed DETAILED DESCRIPTION

[0040] The present invention provides a river sewage purification system and method based on plant populations. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0041] In the description of the present invention, it should be understood that the terms "up, down, left, right, etc." indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and should not be understood as limiting the present invention; in addition, the terms "installation" and "connection" should be understood in a broad sense, and those skilled in the art can understand the specific meanings of the above terms in the present invention according to specific circumstances.

[0042] See also Figures 1 to 4 The present invention provides a river sewage purification system based on plant populations, comprising a plant buffer zone 1, a wetland purification zone 2, a slowdown slope 3 and a still water zone 4 sequentially constructed along the river channel; and also comprising a gravel layer 5 and aquatic plants 6; the plant buffer zone 1 constructed at the river entrance intercepts the water body, and a gravel layer 5 is laid at the bottom of the slowdown slope 3 and the still water zone 4, and aquatic plants 6 are planted on the still water zone 4; the wetland purification zone 2 comprises a water diversion pipe 7, an infiltration pipe 8, a fine gravel layer 9, a water diversion gravel layer 10 and a coarse gravel layer 11; the water diversion pipe 7 is vertically arranged at the junction of the plant buffer zone 1 and the wetland purification zone 2, the infiltration pipe 8 is connected to the bottom of the water diversion pipe 7 and is arranged along the wetland purification zone 2, a penetration hole is opened at the top of the infiltration pipe 8, and the coarse gravel layer 11, the water diversion gravel layer 10 and the fine gravel layer 9 are sequentially laid from bottom to top above the infiltration pipe 8.

[0043] The width of the plant buffer zone 1 is 10-50 meters, accounting for more than two-thirds of the width of the river channel. Reeds, calamus, cattails or willows are mainly selected. The above plants have strong root systems and can fix the soil and absorb excess nutrients. At the same time, planting is carried out by sowing, cuttings or transplanting to ensure that there is enough space between plants to grow and avoid excessive competition.

[0044] In this embodiment, the diameter of the gravel in the fine gravel layer 9 is 35-50 mm, the diameter of the gravel in the coarse gravel layer 11 is 50-80 mm, and the diameter of the gravel in the water diversion gravel layer 10 is greater than the diameter of the gravel in the coarse gravel layer 11. Specifically, the diameter of the gravel in the fine gravel layer 9 is 35 mm, and the diameter of the gravel in the coarse gravel layer 11 is 50 mm. The gravel in the water diversion gravel layer 10 has a larger diameter, and the gravel in the gravel layer has a larger gap, and the water body has a greater flow rate therein, which can speed up the filtration of the water body. It can be seen that the setting of the fine gravel layer 9, the coarse gravel layer 11 and the water diversion gravel layer 10 can achieve effective filtration and cleaning of pollutants through gravels of different particle sizes, thereby improving the purification efficiency of the system.

[0045] In detail, the slowing slope 3 extends from the wetland purification area 2 to the still water area 4 along the direction of the river flow and is inclined, and the back surface slope ratio of the slowing slope 3 is 1:1. The slowing slope 3 extends from the wetland purification area 2 to the still water area 4 along the direction of the river flow and is inclined, and the back surface slope ratio is 1:1, which helps to further slow down the water flow speed and promote the sedimentation of suspended matter and the removal of pollutants.

[0046] Specifically, a gravel layer 5 is laid on the slowing slope 3, and the gravel layer 5 has a larger surface area, which can provide sufficient attachment surface for microorganisms and improve the self-purification ability of the water body. The gravel layer 5 covers the riverbed of the still water area 4, wherein emergent plants are planted in the gravel layer 5 on the riverbed, and the emergent plants can be selected from Lythrum sagittifolia, Cattail, Reed, Calamus, Sagittaria or Iris fulvidraco, which have strong ability to purify water quality.

[0047] Ecological revetments 15 are arranged on both sides of the plant buffer zone 1. The ecological revetments 15 are ecological bases, ecological cages or plant mats. The ecological revetments 15 are arranged on both sides of the plant buffer zone 1, which helps to fix the soil, reduce erosion, slow down the water flow speed, promote the sedimentation of suspended matter, and enhance the stability and ecological benefits of the system. Specifically, the ecological base is a structure composed of natural materials (such as wood, bamboo, etc.), and the ecological base is implanted in the river bank soil to increase the stability of the river bank. The ecological base can provide additional support to prevent soil erosion, and over time, plant roots will grow on these structures, further enhancing their stability. The ecological cage can be a cage made of metal mesh or plastic mesh, filled with rocks or other hard materials. The ecological base is placed on the river bank, which can effectively prevent soil erosion and provide a stable matrix for plant growth. The porous structure of the ecological cage allows the roots of aquatic plants 6 to pass through and blend into the surrounding natural environment. The plant mat is a mat made of plant fibers, which is laid on the river bank and has good water permeability and air permeability, and can support the growth of a variety of plants, thereby forming a natural ecological revetment 15.

[0048] In addition, it also includes ecological beds and aeration plates set in the middle of the water, as well as submerged plants planted on the riverbed. The impact of various measures on water flow is analyzed as follows: 1. The ecological bed is arranged in the middle of the riverbed in a frame-like manner. The carrier material is light in texture and floats with the water flow, which will not cause adverse effects on water diversion and drainage. 2. The placement of microorganisms and the planting of submerged plants can both reduce and mineralize the bottom mud, which is conducive to the expansion of the water-passing section, the increase of water body capacity, and the drainage of the river. 3. The aeration plate is fixed on the riverbed and arranged along the direction of the water flow, which will not cause poor drainage.

[0049] Optionally, the aquatic plants 6 include submerged plants and floating plants, the submerged plants grow in the river mud of the still water area 4, and the floating plants float on the water surface of the still water area 4. The submerged plants are bamboo leaf pondweed, foxtail algae, black algae, Vallisneria, goldfish algae or water chestnuts. The above submerged plants form a dense vegetation layer underwater, which helps to inhibit the growth of algae and maintain the transparency and water quality of the water body. The floating plants are Euryale, water lily, water lily or duckweed. The above floating plants can not only beautify the water surface, but also absorb nutrients in the water through their roots. Preferably, a number of ecological floating beds 16 are set in the still water area 4, and the aquatic plants 6 are planted in the ecological floating beds 16.

[0050] Submerged plants grow in the river mud of the still water area 4, and floating plants float on the water surface. This combination can make full use of the purification potential of different water layers and improve the overall purification effect. In the still water area 4, a number of ecological floating beds 16 are set up to provide a growth matrix for aquatic plants 6, increase biodiversity, and improve the purification capacity and stability of the system. The selected plants are all commonly used aquatic plants, which have a good absorption effect on pollutants. Canna, Lythrum saussurea, Iris, Variegated Reed, Water Lily and Pickerel Grass are planted along the river bank as tall aquatic plants; Sagittaria and Pink Green Foxtail are short plants planted on one side of the river center. The tall plants and short plants are matched in height and staggered to form a good landscape. The inlet and outlet water quality is detailed in Table 1-1:

[0051] Table 1-1: List of inlet and outlet water quality

[0052]

[0053] It also includes a drainage system 13, and the still water area 4 infiltrates underground to form a groundwater flow 12 with water veins, and the groundwater flow 12 is diverted to the main stream of the river through the drainage system 13. By infiltrating underground in the still water area 4 to form a groundwater flow 12 with water veins, and using the drainage system 13 to divert the treated water back to the main stream of the river, the circulation and continuous purification capacity of the system is ensured, while avoiding groundwater pollution. Specifically, the drainage system 13 includes a ground base station and a lifting pump 14, and the lifting pump 14 is installed in the ground base station. The outlet of the lifting pump 14 is located on the main stream of the river. The lifting pump 14 installed in the ground base station can efficiently discharge the groundwater flow 12 formed by infiltration to the main stream of the river, ensuring the smooth flow of water and the stable operation of the system. In this embodiment, a dam body is provided at the rear side of the still water area, and the ground base station is built on the dam body. The still water area 4 is formed between the dam body and the slowing slope 3.

[0054] Example: Dongyingyong water purification and ecological restoration project in Dongying Village, Xinan Street, Sanshui District, Foshan City.

[0055] Sanshui District is located in the subtropics and has a southern subtropical marine monsoon climate. It has abundant rainfall, but it is unevenly distributed. Climate disasters such as low temperature, floods, and droughts occur from time to time. In summer and autumn, it is often affected by tropical storms (typhoons), and lightning disasters are frequent, making it a high-incidence area of ​​thunderstorms.

[0056] The construction period of this project will span the spring with continuous drizzles, and the unfavorable season brings certain difficulties to the construction. In the early stage of the project implementation, it is necessary to add zooplankton and plant aquatic plants. Zooplankton and newly planted aquatic plants are easily preyed on by wild fish in the water, thus affecting the system construction and treatment effect. On-site investigation found that at this stage, the river has not been dredged for a long time, the bottom mud is thick, and the harmful substances in the bottom mud have accumulated for a long time, which is toxic to the roots of planted aquatic plants; the river is often shallow and has poor carrying capacity. Since some sections of the river are located in densely populated residential areas, the impact on surrounding residents should be strictly controlled during the comprehensive treatment and operation of the project. The water body of the project is in a relatively frequent exchange situation, which poses a great challenge to the construction process and the guarantee of implementation effect. Since Dongyingyong is the main drainage channel, the engineering measures must meet the drainage needs as the primary premise.

[0057] Dongying Creek in Dongying Village, Xinan Street, Sanshui District, has a length of about 2,490 meters, a narrowest part of the river of 5 meters, a widest part of 48 meters, a water depth of 0.2 to 1.5 meters, and a total water area of ​​about 41,561 square meters. The northern banks of the river are mostly farmland, the east side is Dongying Village, and there are factories in the southern part. The total amount of pollutants discharged by pollution sources in Dongying Village, the amount of sewage and the concentration are shown in Table 1-2:

[0058] Table 1-2 Summary of the total amount of sewage discharged from Dongying Village and the concentration and total amount of pollutants

[0059]

[0060]

[0061] The planting of submerged vegetation adopts the seedling throwing method, that is, throwing seeds on the water by boat. After one seeding is completed, replanting is carried out, also using the seedling throwing method, and so on until the design requirements are met. In addition, the introduction of microorganisms and the planting of submerged plants can play a role in reducing and mineralizing the bottom mud, which is conducive to the expansion of the water-passing section, increasing the water body capacity, and facilitating the drainage of the river. About 30 to 45 days after the planting of aquatic plants, the submerged plants grow gradually and luxuriantly, and various aquatic animals are put in to further improve the food chain and build a complete water ecosystem.

[0062] In the river channel of Dongying Village River Water Ecological Project, submerged plants such as Vallisneria, Ceratophyllum, Myriophyllum paniculate, and Potamogeton are planted in the river channel with a total length of more than 100 meters, and emergent plants such as Polygonum multiflorum and Water celery are planted on the river bank. The hydration data of the river channel water ecological project are shown in Table 1-3:

[0063] Table 1-3 Summary of hydration data of river water ecological projects

[0064]

[0065]

[0066]

[0067]

[0068] See also Figure 5 , based on plant populations and river sewage purification methods, using the above-mentioned river sewage purification system based on plant populations, including the following steps: S1. Constructing a plant buffer zone 1; setting a plant buffer zone 1 in the direction of river water flow, raising the riverbed and planting emergent plants or water-resistant plants on the width of the river, placing an ecological revetment 15 on the river bank, fixing the soil, reducing erosion, and slowing down the water flow speed, promoting the sedimentation of suspended matter; S2. Setting a wetland purification zone 2; at the junction of the plant buffer zone 1 and the wetland purification zone 2, the river water is guided into the infiltration pipe 8 through the water diversion pipe 7, and the sediment is quickly filtered and cleaned through the fine gravel layer 9 of different sizes, the water diversion gravel layer 10 and the coarse gravel layer 11 on the infiltration pipe 8; S3. Forming a still water zone 4; laying a gravel layer 5 on the riverbed of the still water zone 4, microorganisms attach and form a water body attachment film, and aquatic plants 6 are planted in layers in the still water zone 4; S4. Lifting and filtering water; the groundwater flow 12 formed by infiltration in the still water zone 4 is discharged to the main stream of the river by the lifting pump 14. Optionally, in step S3, submerged plants are planted in the river mud of the still water area 4, and floating plants float on the water surface. The layered planting method makes full use of different layers of the water body, improving the purification efficiency and the stability of the ecosystem.

[0069] In summary, the plant population-based river sewage purification system and method of the present invention constructs a plant buffer zone 1 at the river entrance, uses the root system and stems and leaves of the plants to intercept and absorb some pollutants, slows down the water flow, and settles the suspended matter, thereby performing preliminary purification. After passing through the buffer zone, the water body enters the wetland purification area 2, and the water diversion pipe 7 is vertically arranged at the junction of the plant buffer zone 1 and the wetland purification area 2 to introduce water into the infiltration pipe 8. A coarse gravel layer 11, a water diversion gravel layer 10, and a fine gravel layer 9 are laid from bottom to top above the infiltration pipe 8. The special hierarchical structure helps to filter and adsorb pollutants. After passing through the wetland purification area 2, the water body flows into the slowing slope 3 and the still water area 4. The further slowing of the flow rate is conducive to the deposition of the remaining suspended matter and the stabilization of the water quality, and the gravel layer 5 is laid at the bottom of the still water area 4, which helps microorganisms to attach and grow, and further remove pollutants. Aquatic plants 6 are planted in the still water area 4. These plants absorb nutrients (such as nitrogen, phosphorus, etc.) in the water and promote the decomposition and transformation of organic matter through a symbiotic relationship with microorganisms, thereby further improving the purification effect of the water body and achieving efficient purification of river sewage. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0070] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the present invention.

Claims

1. A river sewage purification system based on plant populations, characterized in that: It includes a plant buffer zone, a wetland purification zone, a slowdown slope and a still water zone constructed in sequence along the river channel; it also includes a gravel layer and aquatic plants; the plant buffer zone constructed at the river entrance intercepts the water body, the bottom of the slowdown slope and the still water zone is paved with a gravel layer, and aquatic plants are planted on the still water zone; the wetland purification zone includes a water diversion pipe, an infiltration pipe, a fine gravel layer, a water diversion gravel layer and a coarse gravel layer; the water diversion pipe is vertically arranged at the junction of the plant buffer zone and the wetland purification zone, the infiltration pipe is connected to the bottom of the water diversion pipe and is arranged along the wetland purification zone, the top of the infiltration pipe is opened with an infiltration hole, and the coarse gravel layer, the water diversion gravel layer and the fine gravel layer are laid in sequence from bottom to top above the infiltration pipe.

2. The plant population-based river sewage purification system according to claim 1, characterized in that: It also includes a drainage system, where the still water area seeps into the ground to form groundwater flows with water veins, and the groundwater flows are led to the main stream of the river through the drainage system.

3. The plant population-based river sewage purification system according to claim 2, characterized in that: The drainage system comprises a ground base station and a lifting pump. The lifting pump is installed in the ground base station, and the water outlet of the lifting pump is located on the main stream of the river.

4. The plant population-based river sewage purification system according to claim 1, characterized in that: Ecological revetments are arranged on both sides of the plant buffer zone, and the ecological revetments are ecological bases, ecological cages or plant mats.

5. The plant population-based river sewage purification system according to claim 1, characterized in that: The aquatic plants include submerged plants and floating plants. The submerged plants grow in river mud in still water areas, and the floating plants float on the water surface in still water areas.

6. The plant population-based river sewage purification system according to claim 5, characterized in that: A plurality of ecological floating beds are arranged in the still water area, and aquatic plants are planted in the ecological floating beds.

7. The plant population-based river sewage purification system according to claim 1, characterized in that: The diameter of the gravel in the fine gravel layer is 35-50 mm, the diameter of the gravel in the coarse gravel layer is 50-80 mm, and the diameter of the gravel in the water diversion gravel layer is greater than the diameter of the gravel in the coarse gravel layer.

8. The plant population-based river sewage purification system according to claim 1, characterized in that: The slowdown slope extends from the wetland purification area to the still water area along the direction of the river flow and is inclined, and the slope ratio of the back surface of the slowdown slope is 1:

1.

9. A method for purifying sewage based on plant populations and rivers, characterized in that: The plant population-based river sewage purification system according to any one of claims 1 to 8 comprises the following steps: S1. Construct plant buffers: Set up plant buffers in the direction of river water flow, raise the riverbed and plant emergent plants or water-tolerant plants across the width of the river, place ecological revetments on the river bank to fix the soil, reduce erosion, slow down the water flow, and promote the sedimentation of suspended matter; S2. Set up a wetland purification area; guide the river water into the infiltration pipe through the water diversion pipe at the junction of the plant buffer zone and the wetland purification area, and quickly filter and clean the sediment through the fine gravel layer of different sizes, the water diversion gravel layer and the coarse gravel layer on the infiltration pipe; S3. Form a still water area; a gravel layer is laid on the riverbed of the still water area, microorganisms attach and form a water body attachment film, and aquatic plants are planted in layers in the still water area; S4. Lifting and filtering water; the groundwater flow formed by infiltration in the static water area is discharged to the main stream of the river by the lifting pump.

10. The method for purifying river sewage based on plant populations according to claim 9, characterized in that: In step S3, submerged plants are planted in the river mud in the still water area, and floating plants float on the water surface.

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