CN103395930A - Ecological slope protection type sewage land infiltration system and ecological slope protection type sewage land infiltration method - Google Patents

Abstract

An ecological slope protection type sewage land infiltration system, including grid pools (2), anaerobic hydrolysis tanks (4) and stepped land infiltration units arranged sequentially along the slope from top to bottom, and the grid pools (2) are connected to ditches (1) Generally speaking, the stepped land infiltration unit includes a multi-stage slope protection permeable bed (5), the slope protection permeable bed (5) is filled with filter material (7), the slope protection permeable bed (5) is cultivated with hygrophyte communities (9), and the adjacent slope protection permeable bed (5) There is a mode conversion component (6) used to control the percolation rate, hydraulic retention time, environment inside the filter layer and water outlet mode. Its advantages are: resistant to the impact of rural sewage water quality and water volume; strong reoxygenation ability and not easy to block; enhanced nitrogen and phosphorus removal effects; green energy saving and economical feasibility; excellent water conservancy and ecological value.

Description

An ecological slope protection type sewage land infiltration system and its infiltration method

technical field

The invention relates to the technical field of sewage treatment, in particular to an ecological slope protection type sewage land infiltration system and its infiltration method applied to rural non-point source pollution control and centralized sewage treatment in hilly and mountainous areas or other suitable sewage treatment .

Background technique

my country began to carry out centralized treatment of sewage point source pollution in the 1980s. After 30 years of development and improvement, my country's sewage point source pollution has been basically controlled, especially in cities and industrial areas. However, in contrast, the water quality of rivers and lakes in my country has remained unsatisfactory in the past ten years. A large amount of money and manpower have been spent on the treatment of various polluted water bodies, but there is still no lasting and obvious effect. The root cause lies in the weakness of non-point source pollution control. .

my country's agricultural areas account for more than 8% of the country's land area, and most of them are located in relatively developed water systems and water network areas. The range of these water systems and water systems accounts for about 35% of the country's land area. Since my country is a mountainous country, 50% of the agricultural areas More than 100% are located in hills and mountainous areas. Once a large amount of non-point source pollution in this area enters the upstream water system through farmland drainage and rainwater runoff, it is bound to spread rapidly to the entire basin. In my country's agricultural production activities, the use of nitrogen and phosphorus fertilizers still lacks scientific guidance at this stage. Although my country's arable land accounts for only 10% of the world's total, the use of nitrogen and phosphorus fertilizers accounts for 30% of the world. Irrigation, rainfall and surface runoff will take away a large amount of small particles, water-soluble nutrients, various pathogenic microorganisms and garbage. Leading to serious water eutrophication, from the Dianchi Lake in the inland plateau to the Dongting Lake and Poyang Lake in the plain area, and then to the offshore areas in the coastal area are facing severe eutrophication crisis. By 2012, 15 provinces, autonomous regions and municipalities along the coast and inland of my country were already in high-risk areas of non-point source pollution. Severe eutrophication not only reduced the health of water bodies, broke the ecological balance, but also affected the people in the water system area. health and the normal conduct of agricultural production activities. In the long run, a series of bad consequences caused by non-point source pollution will have a negative impact on my country, foreign agricultural trade, people's living standards, and even economic development. The concept of building an ecological civilization proposed at the "18th National Congress" includes the control of non-point source pollution. attention.

Compared with sewage treatment in urban areas, the economic conditions in rural areas are limited, the sources of sewage are scattered, and the water quality and quantity fluctuate greatly. Therefore, it is difficult to use the conventional and energy-intensive anaerobic-anoxic-aerobic treatment process (Anaerobic-Anoxic- Oxic, referred to as A ² /O), sequencing batch activated sludge reactor (Sequencing batch reactor, referred to as SBR) process. The current technology for controlling non-point source pollution mainly includes three aspects: nitrogen and phosphorus source interception, middle-stage control and terminal treatment. Due to the vast area of agricultural areas, complex topography and economic constraints, it is difficult to remove nitrogen and phosphorus in the middle section. Therefore, source interception and terminal treatment have received attention and development. Among them, the source interception technology mainly refers to the interception and reuse in the area where nitrogen and phosphorus are produced. The main technologies include ecological ditches, grass ditches, ecological ponds, artificial wetlands and land infiltration, etc., while the terminal treatment mainly refers to nitrogen and phosphorus-rich sewage. Intercept and treat the runoff and water before it enters the water body. The main technical means include front reservoir, vegetation buffer zone, ecological permeable dam, etc.

Among them, as a relatively old sewage treatment process, land infiltration is often used in sewage treatment in rural areas, especially in western countries. According to the survey, the penetration rate of various forms of land infiltration devices in rural areas of the United States has reached 63%, while that in Sweden has reached 80%. Germany, Canada and other countries also have a large number of stable land infiltration facilities in operation. Land infiltration mainly includes slow infiltration system, fast infiltration system, surface overflow system, constructed wetland system and underground infiltration system, etc. Among them, fast infiltration system and underground infiltration system are more commonly used, and the former is economical, applicable and resistant to hydraulic load The capacity is outstanding, but it faces the limitation of low processing efficiency; the latter has high processing efficiency and strong adaptability to environmental conditions, but it faces the problems of clogging, hypoxia and aging failure of filter materials. Similarly, the current land infiltration treatment technologies commonly used in my country often face shortcomings including filter material clogging, infrastructure maintenance costs, high energy consumption in operation, and poor environmental landscape effects. In addition, the treatment of nitrogen and phosphorus in ordinary land infiltration systems mainly depends on the adsorption of filter materials rather than conversion and degradation, especially in the removal of phosphorus. Therefore, the present invention is mainly developed for the following objectives: (1) tolerance to rural areas The impact of sewage water quality and water volume; (2) strong reoxygenation capacity and not easy to block; (3) enhanced nitrogen and phosphorus removal effects; (4) green energy saving and economical feasibility; (5) excellent water conservancy and ecological value.

Contents of the invention

The purpose of the present invention's ecological slope protection type sewage land infiltration system and its infiltration method is to provide a low energy consumption, high efficiency ecological slope protection type sewage land infiltration system and its infiltration method, which is suitable for the centralized treatment of rural sewage in my country. It has versatility, economy, stability and landscape.

An ecological slope protection type sewage land infiltration system, including a grille pool 2, an anaerobic hydrolysis pool 4 and a stepped land infiltration unit arranged sequentially along the slope from top to bottom, and the grille pool 2 is connected to the ditch 1 Generally, the stepped land infiltration unit includes a multi-stage slope protection permeation bed 5, the inside of the slope protection permeation bed 5 is filled with a filter material 7, and a hygrophyte community 9 is cultivated on the slope protection permeation bed 5, and the adjacent slope protection permeation bed 5 A mode conversion component 6 for controlling the percolation rate, hydraulic retention time, environment inside the filter layer and water outlet mode is arranged between them.

The mode conversion assembly 6 includes an inverted T-shaped tube 11, one interface at the lower end of the inverted T-shaped tube 11 is located in the slope protection permeation bed 5 of the previous stage, and the other interface at the lower end of the inverted T-shaped tube 11 is located at the next stage A low-level water outlet 12 is formed above the slope protection permeation bed 5, and the top interface of the inverted T-shaped pipe 11 is located above the slope protection permeation bed 5 of the next level to form a high-level water outlet 13, and the lower part of the high-level water outlet 13 is provided with an overflow weir tank 14, The overflow weir tank 14 is provided with a V-shaped triangular water distribution weir 15; the end of the low water outlet 12 is provided with a mode switching valve 16.

The cross-section of the V-shaped triangular water distribution weir 15 is V-shaped, the water inlet side of the V-shaped triangular water distribution weir 15 is a rectangular weir, and the water outlet side of the V-shaped triangular water distribution weir 15 is a continuously arranged triangular weir.

The vertical height of the V-shaped triangular water distribution weir 15 from the next-level slope protection permeation bed 5 is greater than 30 cm.

The thickness of the slope protection permeable bed 5 is 30-100 cm.

The slope of the foundation bed of the slope protection permeable bed 5 along the water flow direction is 0.3-3%.

The front end of the ecological slope protection type sewage land infiltration system of the present invention is provided with transcending pipes and canals to protect the system from the impact of heavy rain and flood.

The end of the ecological slope protection type sewage land infiltration system of the present invention is provided with a nitrogen and phosphorus reuse interface 10 to facilitate the realization of nitrogen and phosphorus reuse.

An ecological slope protection type sewage land infiltration method comprises the following steps:

① The non-point source sewage (including previous rainwater and domestic sewage) collected through ecological ditches or surface overflow first enters the grid pool at the upper end of the slope to filter out garbage and large suspended particles, and the effluent directly flows into the anaerobic hydrolysis tank to remove solid suspended solids and some Biochemical oxygen demand, while stabilizing water quality;

②The effluent pretreated in step ① enters the stepped land infiltration unit through the overflow weir, and removes most of the biochemical needs through the falling water aeration, adsorption and interception, microbial degradation and utilization of the ecological filter layer, and the absorption and transformation of the wet plant community. Oxygen, suspended solids and pathogenic microorganisms, especially the effective removal of nitrogen and phosphorus through the mode conversion components between the multi-stage slope protection permeable beds;

③The effluent infiltrated by the land in step ② is discharged from the overflow weir, and used for farmland irrigation through the nitrogen and phosphorus reuse port, or advanced treatment is carried out through the wetland or trickling filtration system, and the effluent is discharged into the natural water body.

The present invention is realized in this way: in the bottom opening mode, the sewage directly flows out from the low water outlet at the bottom of the filter layer, the pressure difference of the water head of the filter layer increases, and rapid percolation is realized. , the filter layer maintains an oxygen-enriched state. At this time, the filter material mainly filters out large particles of organic matter through interception, and then the filter material microorganisms aerobically digest and decompose the adsorbed organic pollutants, thereby reducing the biochemical oxygen demand, total nitrogen, and total phosphorus of the sewage, and avoiding the clogging of large particles of organic matter. filter layer. In this stage, the hygrophyte community realizes nitrification reaction through the root ecosystem (root absorption, respiration, rhizobia and root nitrogen microorganisms), and nitrogen is trapped in the form of nitrate nitrogen and nitrite nitrogen. Following the international ecological circle, at the same time, the phosphorus-accumulating bacteria community in the filter layer absorbs a large amount of PHA (phosphorus polymer) adhering to the surface of the bacterial micelles through the microbial metabolism process, and converts it into intracellular nutrients to complete the removal of phosphorus. At the same time Provide an energy source for the biosphere in the filter layer.

In the water outlet mode through the top of the inverted T-shaped pipe, the sewage enters the next filter layer from the high-level outlet, and the difference between the inlet and outlet water heads through the filter layer becomes smaller, and the filter layer enters the slow percolation stage. Surface re-oxygenation, due to the prolonged residence time of sewage, in this mode, the filter layer is in an oxygen-poor state, and the filter material mainly traps smaller particles of organic pollutants through adsorption, and then is digested by facultative anaerobic microorganisms in the filter material , to achieve the removal of biochemical oxygen demand, and at the same time release part of the nitrogen and phosphorus compounds that have been adsorbed and have not been absorbed and transformed. At this stage, the root system of the hygrophytic plant community mainly realizes anaerobic denitrification reaction through the rhizobia in the root system and the denitrifying bacteria in the surrounding ecosystem. The nitrate nitrogen accumulated in the aerobic stage is converted into nitrogen and overflows the filter layer. The nitrogen dissipation process can enhance the exchange of the material in the filter layer with the atmospheric material. At the same time, the biological activity of phosphorus accumulating bacteria is inhibited in the anaerobic state, and the phosphorus compounds in the bacteria begin to be released in excess, and they attach to the surface of the bacterial micelles in the form of PHA (phosphorus polymer), waiting to enter the aerobic condition for absorption and transformation. In this mode, the water from the filter layer enters the overflow weir tank 14, and enters the next filter layer through the V-shaped triangular water distribution weir in the form of water curtain and drip filtration. When the sewage descends and enters the filter layer, it is realized by gas-liquid interface exchange and impact dispersion. Reoxygenation. the

The sewage treatment principle of the present invention is: through the exchange of infiltration modes, the system can realize the alternation of oxygen-enriched-oxygen-poor-oxygen-enriched-oxygen-poor conditions, which is similar to the sewage anoxic-aerobic treatment of urban sewage treatment plants process and the sequencing batch activated sludge reactor process, through such an alternation, the removal of biochemical oxygen demand, nitrogen and phosphorus can be repeatedly achieved in the same filter layer, and finally the nitrogen will escape into the atmosphere, and the phosphorus will mainly accumulate in the higher In microbial (crustacea, earthworms, etc.) and hygrophytic plant communities, final disposal of phosphorus can be achieved by periodically harvesting the plants. At the same time, a complete and healthy ecological circle can realize the effective removal of pathogenic microorganisms, thereby realizing the sewage treatment process. The more the number of ecological filter layers and the shorter the conversion cycle, the better the treatment effect of the system.

The advantages of the ecological slope protection type sewage land infiltration system and the infiltration method thereof of the present invention are:

1. The present invention realizes sewage reoxygenation through various methods such as natural reoxygenation on the surface of the filter material, falling water reoxygenation, and negative pressure reoxygenation to ensure sufficient oxygen content in the ecological filter layer, which not only ensures the treatment effect of biochemical oxygen demand, but also It can effectively avoid the clogging of the filter layer;

2. The present invention realizes the alternate conversion of oxygen-enriched and oxygen-poor in each filter layer through the series connection of multiple filter layers and mode conversion components, which can effectively enhance the removal efficiency of nitrogen and phosphorus, especially phosphorus that is difficult to degrade by ordinary treatment systems;

3. By controlling the mode conversion component, the infiltration speed of the filter layer can be effectively controlled. In addition to opening the transcending pipes and canals during the rainy season or heavy rain, the number of fast filter layers can be increased to effectively respond to the impact of water volume; in the dry season The number of slow filter layers can be appropriately increased to cope with water reduction and water quality deterioration; wherein the ecological filter layer filter material and wet plant communities can ensure normal growth under long-term immersion or extreme drought conditions; Strong tolerance to water quality impact changes;

4. The present invention is based on ecological slope protection, and the stepped land infiltration unit itself can be used as slope protection, which can effectively reduce the hazards caused by disasters such as soil erosion, landslides, and debris flows, and ensure the safety of the economic property of residential communities; if The lakes built on rivers, lakes, ponds and canals can also be used as water conservancy facilities, and at the same time have the functions of sewage source treatment and protection of regional water conservancy safety;

5. The ecological slope protection constructed by the present invention is in the shape of steps, and wet plants are planted at each level, and the "garden waterfall"-style landscape effect is simulated through the organic combination of filter layer drop water, water discharge and plant communities. The photosynthesis of plant communities and water flow and the regulation and storage of temperature and humidity endow the system with great ecological landscape value;

6. The present invention effectively utilizes the height difference between residential buildings and fields in hilly areas. The tail water of the system can flow into the receiving water body, and can also flow naturally into fields and vegetable fields to realize nitrogen and phosphorus reuse, which not only realizes resource recovery but also saves the depth of sewage processing link;

7. The invention utilizes the natural topography of the slope to reduce infrastructure investment, and at the same time does not rely on any artificial energy and power in the process of collection, treatment, discharge, and reuse, and completely realizes zero energy consumption; it can also be quickly and conveniently replaced when maintenance is required. The completion saves economic input to the greatest extent, and can also realize resource feedback through the output of green plants and ecological perception.

Description of drawings

Fig. 1 is the overall structure schematic diagram of ecological slope protection type sewage land infiltration system of the present invention;

Fig. 2 is the structural representation of mode transformation assembly;

Fig. 3 is a structural schematic diagram of a V-shaped triangular water distribution weir;

In the figure, 1 is the ditch, 2 is the grid tank, 3 is the grid, 4 is the anaerobic hydrolysis tank, 5 is the multi-level slope protection permeation bed, 6 is the mode conversion component, 7 is the filter material, and 9 is the wet plant Community, 10 is the nitrogen and phosphorus reuse interface, 11 is the inverted T-shaped pipe, 12 is the low water outlet, 13 is the high water outlet, 14 is the overflow weir tank, 15 is the V-shaped triangular water distribution weir, 16 is the mode conversion valve.

Detailed ways

Below in conjunction with the accompanying drawings, the present invention is further described: as shown in Figure 1-3, a kind of ecological slope protection type sewage land infiltration system includes grid tank 2 arranged in sequence from top to bottom along the slope slope, anaerobic hydrolysis The pool 4 and the stepped land infiltration unit, the grid pool 2 is connected to the ditch 1, the stepped land infiltration unit includes a multi-stage slope protection permeation bed 5, and the slope protection permeation bed 5 is filled with filter material 7 A hygrophyte community 9 is cultivated on the slope protection infiltration bed 5, and a mode conversion component 6 for controlling the infiltration rate, hydraulic retention time, internal environment of the filter layer and water outlet mode is arranged between the adjacent slope protection infiltration beds 5 .

The mode conversion assembly 6 includes an inverted T-shaped tube 11, one interface at the lower end of the inverted T-shaped tube 11 is located in the slope protection permeation bed 5 of the previous stage, and the other interface at the lower end of the inverted T-shaped tube 11 is located at the next stage A low-level water outlet 12 is formed above the slope protection permeation bed 5, and the top interface of the inverted T-shaped pipe 11 is located above the slope protection permeation bed 5 of the next level to form a high-level water outlet 13, and the lower part of the high-level water outlet 13 is provided with an overflow weir tank 14, The overflow weir tank 14 is provided with a V-shaped triangular water distribution weir 15; the end of the low water outlet 12 is provided with a mode switching valve 16.

The vertical height of the V-shaped triangular water distribution weir 15 from the next-level slope protection permeation bed 5 is greater than 30 cm.

The end of the ecological slope protection type sewage land infiltration system of the present invention is provided with a nitrogen and phosphorus reuse interface 10 to facilitate the realization of nitrogen and phosphorus reuse. The biochemical oxygen demand removal rate of sewage after the stepped land infiltration unit can reach more than 70%, but the water still contains a certain amount of nitrogen and phosphorus that will not cause eutrophication, because most of the nitrogen and phosphorus come from excess If the chemical fertilizers used are discharged directly, resources will be wasted. The nitrogen and phosphorus reuse interface 10 is installed at the outlet of the ecological filter layer. After the outlet water passes through the overflow weir, it enters the cultivated land or vegetable field at the bottom of the slope through the outlet, and realizes nitrogen and phosphorus reuse through irrigation. , and the sewage after the reuse of farmland and vegetable fields is equivalent to passing through the surface flooding land infiltration system, and the residual nitrogen and phosphorus are absorbed and utilized by plant microorganisms, which fully meets the discharge requirements. At the same time, this process can help realize the local water cycle in villages This has a positive effect on the protection of village water resources and the realization of ecological landscapes; if the tail water needs to be discharged into unpolluted or protected natural water bodies, the effluent can enter ecological ponds and wetland systems for advanced treatment, and can also be connected to the former After the water quality reaches the standard, it can be discharged into the natural water body.

Ditch 1 is an anti-seepage concrete ditch with a cross-section of length-to-width ratio of 1:2, which receives sewage from the non-point source sewage collection system. Grid pool 2 is a double-channel vertical grid pool, and the solid pollutants on the grid are manually cleaned. Fish to remove.

The anaerobic hydrolysis pool 4 is a square anti-seepage concrete pool, and a geotechnical anti-seepage film is laid on the pool wall and the bottom of the pool to prevent the acidification solution from leaking. Several horizontal baffles can be set in the anaerobic hydrolysis tank 4 as required to evenly distribute the water flow, slow down the flow rate and enhance the removal effect of suspended solids. After the sewage enters the anaerobic hydrolysis tank 4, the hydraulic retention time exceeds 1 day, and anaerobic conditions are formed. The organic matter in the sewage is biodegraded by facultative anaerobic bacteria and obligate anaerobic bacteria, especially easily leading to land infiltration During this process, the large particle organic pollutants blocked by the system are hydrolyzed and acidified into smaller particle organic matter and easily degradable organic acids. By improving the biodegradability of the treated sewage, the suspended solids are significantly reduced and are not easy to cause blockage.

The multi-stage slope protection infiltration bed 5 of the stepped land infiltration unit is built along the terrain of the natural slope, and is poured with anti-seepage concrete into a ladder shape. Each level is left empty as a filter bed and a retaining wall is set. 0.3-3% slope. Different filter layers are connected in series through the mode conversion component 6 . A number of water outlets are opened at the lower part of the end of each stage, one end is directly connected to the upper surface of the next filter layer, and the other end is connected to the inverted T-shaped pipe 11 in the water retaining wall (see Figure 2), leading water upward to the overflow weir, passing through Water falls from the weir into the next filter layer.

In terms of filter material selection, the filter material of the ecological filter layer can be mainly made of ceramsite, gravel, cinder, or other local aggregates, such as vermiculite, diatomaceous earth, etc. Diversity and environmental friendliness. The filter material in each ecological filter layer can be composed of the same kind of filter material, or several types can be mixed. The thickness of the filter layer can be selected within 30-100cm, but the average particle size of the filter material of the filter layer varies with the direction of water flow. Decrease gradually, and the particle size range can be selected from 1-15mm according to specific working conditions. In areas where conditions permit, a composite filter layer with mixed particle sizes can be laid in the same filter layer to enhance the sewage treatment effect. If the plane area of the filter layer is large, it is necessary to consider laying permeable bricks or blocks on the surface of the filter material to build maintenance channels.

The outlet of the overflow weir tank 14 is designed as a "∨" shape to ensure that the water flow can form a water curtain without flowing down the retaining wall. The outlet water is evenly distributed in the lateral direction, and at the same time, the outlet water forms a dispersed water curtain or trickling flow state. According to the research conclusions of Chao Lei, Hu Cheng, etc. in 2011, the water curtain or drip filtration form is more conducive to falling water reoxygenation. At the same time, in order to ensure sufficient reoxygenation time for falling water, the thickness of the filter layer should not be less than 30cm. At this height of falling water, the dissolved oxygen in water can reach 2mg/L. Correspondingly, in the area where the next filter layer receives the water flow, plants should not be planted, but a groove should be left to form a horizontal ditch, and the falling water flows into the ditch, forming a large number of air bubbles and vortexes through the impact, thereby enhancing the flow of falling water. The interaction between water flow and water body air greatly enhances the efficiency of falling water reoxygenation.

Further, suitable wet plants should be selected on the surface of the infiltration bed 5 of the multi-stage slope protection. Plant selection is mainly based on native plants, taking into account the nitrogen and phosphorus treatment effects of plants. Among them, the local indigenous wet plants are the most recommended, and emergent herbs and shrubs can also be planted appropriately, including yellow cattails, cannas, Alisma and reeds. The planting process is completed by artificial sowing, and some nutrient substrates can be selected to strengthen the growth of plant communities, but chemical fertilizers should not be used. In addition, considering that the amount of nitrogen and phosphorus stored by the plant community during the summer growth period is quite large, it is possible to release excessive nitrogen and phosphorus in autumn and winter or release nitrogen and phosphorus into the environment due to soaking in the rainy season and torrential rain. Therefore, it is necessary to organize villagers to harvest plants every year It is used for composting, poultry breeding, economic production, etc. to achieve environmental and economic benefits.

In the present invention, the front end of the system can be constructed with an initial rainstorm separation device, connected with flood control ditches, and provided with a transcending pipeline system. When the rainstorm comes, intercept the initial rainstorm for treatment. When the flood comes, short-circuit the system by overriding the pipeline to prevent the flood from washing the system and causing system damage or loss of filter material.

An ecological slope protection type sewage land infiltration method comprises the following steps:

① Non-point source sewage (including previous rainwater and domestic sewage) collected through ecological ditches or surface overflow first enters the grid pool at the upper end of the slope to filter garbage and large suspended particles, and the effluent directly flows into the anaerobic hydrolysis tank to remove solid suspended solids and some Biochemical oxygen demand, while stabilizing water quality;

②The effluent pretreated in step ① enters the stepped land infiltration unit through the overflow weir, and removes most of the biochemical needs through the falling water aeration, adsorption and interception, microbial degradation and utilization of the ecological filter layer, and the absorption and transformation of the wet plant community. Oxygen, suspended solids and pathogenic microorganisms, especially the effective removal of nitrogen and phosphorus through the mode conversion components between the multi-stage slope protection permeable beds;

③The effluent infiltrated by the land in step ② is discharged from the overflow weir, and used for farmland irrigation through the nitrogen and phosphorus reuse port, or advanced treatment is carried out through the wetland or trickling filtration system, and the effluent is discharged into the natural water body.

Claims (7)

1. An ecological slope protection type sewage land infiltration system is characterized in that: it comprises a grid pool (2), anaerobic hydrolysis tank (4) and a stepped land infiltration unit arranged successively along the slope from top to bottom, the grid The pool (2) is connected with the ditch (1), and the stepped land infiltration unit includes a multi-stage slope protection seepage bed (5), the inside of the slope protection seepage bed (5) is filled with filter material (7), and the slope protection seepage bed (5) is cultivated with hygrophyte communities (9), A mode conversion component (6) for controlling infiltration velocity, hydraulic retention time, internal environment of the filter layer and water outlet mode is arranged between adjacent slope protection permeation beds (5). 2. The ecological slope protection type sewage land infiltration system according to claim 1, characterized in that: the mode conversion component (6) includes an inverted T-shaped pipe (11), and the lower end of the inverted T-shaped pipe (11) is located at the upper end In the slope protection permeation bed ⑸, another interface at the lower end of the inverted T-shaped tube ⑾ is located above the slope protection permeation bed ⑸ of the next level to form a low water outlet ⑿, and the top interface of the inverted T-shaped tube ⑾ is located at the next level of slope protection permeation bed ⑸ A high-level water outlet ⒀ is formed above, and the lower part of the high-level water outlet ⒀ is provided with an overflow weir tank ⒁, and the outside of the overflow weir tank ⒁ is provided with a V-shaped triangular water distribution weir ⒂; the end of the low-level water outlet ⑿ is provided with a mode conversion Valve ⒃. 3. The ecological slope protection type sewage land infiltration system as claimed in claim 2, characterized in that: the cross-section of the V-shaped triangular water distribution weir (10) is V-shaped, and the water inlet side of the V-shaped triangular water distribution weir (19) is rectangular Weir, the outlet side of the V-shaped triangular water distribution weir mouth ⒂ is a continuously arranged triangular weir. 4. The ecological slope protection type sewage land infiltration system according to claim 2 or 3, characterized in that: the vertical height of the V-shaped triangular water distribution weir ⒂ from the next level of slope protection infiltration bed ⑸ is greater than 30 cm. 5. The ecological slope protection type sewage land infiltration system according to claim 1, characterized in that: the thickness of the slope protection permeation bed (5) is 30-100 cm. 6. The ecological slope protection type sewage land infiltration system according to claim 1, characterized in that: the slope of the slope protection permeable bed (5) along the water flow direction is 0.3-3%. 7. utilize the land infiltration method of the ecological slope protection type sewage land infiltration system described in any one of claim 1-6, comprise the steps: ① The non-point source sewage collected through ecological ditches or overland flow first enters the grid pool at the upper end of the slope to filter out garbage and large suspended solids, and the effluent flows directly into the anaerobic hydrolysis tank to remove solid suspended solids and part of the biochemical oxygen demand, while stabilizing water quality ; ②The effluent pretreated in step ① enters the stepped land infiltration unit through the overflow weir, and removes most of the biochemical needs through the falling water aeration, adsorption and interception, microbial degradation and utilization of the ecological filter layer, and the absorption and transformation of the wet plant community. Oxygen, suspended solids and pathogenic microorganisms, especially the effective removal of nitrogen and phosphorus through the mode conversion components between the multi-stage slope protection permeable beds; ③The effluent infiltrated by the land in step ② is discharged from the overflow weir, and used for farmland irrigation through the nitrogen and phosphorus reuse port, or advanced treatment is carried out through the wetland or trickling filtration system, and the effluent is discharged into the natural water body.

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