An assembled biological retention pond with nitrogen and phosphorus removal functions

Abstract

The present invention discloses an assembled biological retention pond with nitrogen removal and phosphorus removal functions, which relates to the technical field of rainwater treatment, and includes a water collection pool and several modules. The module includes an anaerobic pool and an aerobic pool, and the internal matrix of the two is the same, and from top to bottom, they include a pebble water distribution layer, a planting layer, a pyrite layer, a transition layer, and a gravel layer. At the gravel layer, the two are connected by a water pipe, and the aerobic pool is connected to the water collection pool through a water collection pipe. A vent pipe is vertically arranged in the aerobic pool, and the vent pipe extends to the gravel layer; a drainage pipe is installed on the top of one side of the anaerobic pool, and a main pipe is installed on the top of one side of the aerobic pool. The main pipe is connected to the municipal rainwater pipe. Several auxiliary pipes are arranged in the water collection pool, and the top of the auxiliary pipe is connected to the main pipe for extracting water from the water collection pool. Several clamps are installed on the outer wall of the main pipe, and the two ends of the clamps are fixedly connected to the edge of the pool by screws. The vent pipe is fixedly connected to the clamp on the outer wall of the main pipe by a mounting piece. This solution improves the ability to remove nitrogen and phosphorus pollutants in rainwater.

Description

Technical Field

[0001] The invention relates to the technical field of rainwater treatment, and in particular to an assembled biological retention pond with nitrogen and phosphorus removal functions. Background Art

[0002] When it rains in mountainous cities, the confluence time is short and the runoff volume is large, resulting in complex hydrological conditions and an increased threat of pollution caused by rainwater erosion. Publication No. CN116065681A discloses an assembled bioretention facility and its forming method, which solves the problem of rainwater discharge in the water storage space at different water levels and controls the probability of urban waterlogging, but cannot solve the problem of rainwater quality pollution, and cannot be effectively applied in mountainous cities. Publication No. CN217103489U discloses a bioretention pond, which solves the technical drawbacks of poor runoff regulation and pollution purification effects of bioretention ponds when the filler soil permeability coefficient does not meet the standard, especially in the face of heavy rain. However, in actual use, bioretention ponds with similar structures still have many defects, such as: existing sponge city rainwater bioretention facilities cannot effectively remove soluble pollutants in rainwater, such as nitrogen and phosphorus pollution. In order to further improve the removal capacity of rainwater biological retention facilities for nitrogen and phosphorus pollutants, facility matrix improvement and structural optimization have become effective ways. The methods for improving the matrix and structure of rainwater retention facilities still have the disadvantage of judging the addition ratio of the facility matrix based on artificial experience, lacking a quantitative decision-making method that is adapted to local conditions, and the existing schemes are mostly determined based on plain terrain, which lacks effectiveness in mountainous landforms. Different construction personnel have different modes and proportions of matrix addition in rainwater biological retention facilities, which further reduces the facility's removal capacity for nitrogen and phosphorus pollutants. Therefore, it is necessary to design an assembled biological retention pond based on denitrification and phosphorus removal. Summary of the invention

[0003] In order to solve the deficiencies of the prior art, the present invention provides an assembled biological retention pond with nitrogen and phosphorus removal functions, which improves the ability to remove nitrogen and phosphorus pollutants in rainwater.

[0004] In order to achieve the purpose of the present invention, the following scheme is proposed:

[0005] The utility model discloses an assembled biological retention pond with the functions of removing nitrogen and phosphorus, comprising a water collection tank and a plurality of modules.

[0006] Each module includes an anaerobic tank and an aerobic tank. The internal matrix of the anaerobic tank and the aerobic tank is the same, including a pebble water distribution layer, a planting layer, a pyrite layer, a transition layer, and a gravel layer from top to bottom. At the gravel layer, the anaerobic tank and the aerobic tank are connected by a water pipe, and the aerobic tank is connected to the water collecting tank through a water collecting pipe. The water collecting pipe is also connected to the gravel layer of the aerobic tank, and the water pipe and the water collecting pipe are located on opposite sides of the aerobic tank. A ventilation pipe is vertically provided in the aerobic tank, and the bottom of the ventilation pipe extends to the gravel layer. The ventilation pipe is used to provide oxygen to the aerobic tank to improve the purification efficiency of rainwater.

[0007] A drainage pipe is installed on the top of one side of the anaerobic tank, which is used to drain rainwater into the anaerobic tank. A main pipe is installed on the top of one side of the aerobic tank, which is connected to the municipal rainwater pipe. Several auxiliary pipes are installed in the water collection pool, and the top of the auxiliary pipe is connected to the main pipe. The auxiliary pipe is used to extract water from the water collection pool. Several clamps are installed on the outer wall of the main pipe, and the two ends of the clamp are fixedly connected to the edge of the pool by screws. In order to improve the stability of the ventilation pipe, the ventilation pipe is fixedly connected to the clamp on the outer wall of the main pipe through a mounting piece.

[0008] Furthermore, the planting layer matrix filler is a mixture of sandy loam and quartz sand with a volume ratio of 14~17:86~83. The planting layer has a penetration rate of not less than 150mm / h and a depth of not less than 450mm. The planting layer is used to plant plants, and pollutants in rainwater are preliminarily purified by plants.

[0009] Furthermore, the matrix filler of the pyrite layer is a mixture of pyrite and quartz sand with a volume ratio of 2~3:8~7. The depth of the pyrite layer is 450mm~550mm. The pyrite layer can improve the efficiency of rainwater dephosphorization and nitrogen removal through the autotrophic denitrification of pyrite.

[0010] Furthermore, the matrix filler of the transition layer is quartz sand, and its particle size is 5%: 10%: 30%: 30%: 25% according to the ratio of 5~10 mesh: 10~20 mesh: 20~30 mesh: 30~60 mesh: 60~140 mesh respectively. The depth of the transition layer is not less than 100 mm, and the depth of the gravel layer is not less than 100 mm. The transition layer can effectively filter impurities in rainwater and prevent impurities from entering the water supply pipe or water collection pipe.

[0011] The working principle of the biological retention tank is: the drainage pipe discharges rainwater into the corresponding anaerobic tank; after the anaerobic tank performs primary purification treatment on the rainwater, the rainwater flows into the aerobic tank through the water pipe; after the aerobic tank performs secondary purification treatment on the rainwater, the rainwater flows into the collection tank through the collection pipe; the collection tank can store the purified rainwater, thereby achieving the effect of reducing the amount of rainwater and improving the efficiency of flood prevention and water management; the purified rainwater can be reused, saving water resources; the rainwater in the collection tank can also be pumped to the main pipe through the secondary pipe, and finally flow into the municipal rainwater pipe.

[0012] Local runoff volume control is determined by:

[0013]

[0014] Where:

[0015] V——Local runoff volume control (m 3 );

[0016] D——The design rainfall corresponding to the design annual runoff control rate of the bioretention pond (mm) shall be determined in accordance with the relevant provisions of the current national standard "Sponge City Construction Evaluation Standard" GB / T 51345;

[0017] F——catchment area served by the bioretention pond (m 2 );

[0018] ——The comprehensive rainfall runoff coefficient of the catchment area served by the biological retention pond.

[0019] Investigate local rainfall conditions, determine rainfall and catchment area, as well as the scope of construction. Determine the number and combined area of ​​modules in the bioretention pool based on local actual conditions.

[0020] The number of modules in the bioretention tank is determined by:

[0021]

[0022] Where:

[0023] n – the number of modules in the bioretention pond;

[0024] V——Local runoff volume control (m 3 );

[0025] m——Unit area of ​​the module in the bioretention pond (m 2 ), it is recommended to set the module to 1000mm×1000mm, that is, the total area of ​​the aerobic tank and the anaerobic tank is 1m 2 .

[0026] Furthermore, the specific connection method of the vent pipe and the mounting piece is as follows: a collar is fixedly provided on the outer wall of the vent pipe, an L-shaped plate is provided on the outer wall of the collar, the mounting piece includes a base, a locking block and a cover plate, the base is fixedly provided on the edge of the pool, and three interconnected first grooves, a second groove and a third groove are provided on the top of the base. In the top view of the base, the three grooves are arranged in the shape of a "earth" character, wherein the major axis of the first groove is parallel to the major axis of the main pipe, and the ends of the second groove and the third groove both pass through the side wall of the base, the locking block is slidably provided in the first groove, one end of the locking block is located in the third groove, and the end is semicircular, and the other end of the locking block is connected to the base through a spring, an avoidance groove is provided on the top of the locking block, the L-shaped plate is assembled in the second groove, and the longitudinal section of the L-shaped plate passes through the avoidance groove, the right-angled portion of the L-shaped plate faces one side of the spring, the right-angled portion hooks the locking block, the cover plate covers the base and is connected to the first end of the clamp by a screw, and is used to unlock the L-shaped plate when the pin is inserted into the third groove to squeeze the locking block.

[0027] Furthermore, the width of the second groove is consistent with the size of the L-shaped plate transverse section, the top surface of the L-shaped plate is in close contact with the cover plate, and the L-shaped plate transverse section is in close contact with the end surface of the clamp.

[0028] Furthermore, a limiting groove is provided at the top of the first end of the clamp, and a block is provided on the side of the cover plate facing the clamp. The block matches in the limiting groove. The block can further improve the stability of the cover plate and prevent the cover plate from shifting in the horizontal plane and deviating from the base.

[0029] Furthermore, the water pipe is arranged to be inclined downward from the anaerobic tank to the aerobic tank.

[0030] Furthermore, the outer walls of the water supply pipe and the water collection pipe are provided with an anti-permeability layer and a waterproof layer. The anti-permeability layer is located on the inner side of the waterproof layer. The anti-permeability layer and the waterproof layer play a protective role to prevent moisture in the soil from penetrating into the interior of the water supply pipe or the water collection pipe and causing pollution to the purified rainwater.

[0031] The beneficial effects of the present invention are:

[0032] 1. The number of modules can be determined according to the local rainfall conditions and the scope of construction. An anaerobic tank and an aerobic tank are used as one module. The two tanks can achieve different pollutant removal effects. The setting of the pyrite layer improves the efficiency of nitrogen and phosphorus pollutant removal; the anaerobic tank and the aerobic tank can store rainwater, which not only has a flood control effect, but also is conducive to the full purification of rainwater; the water collection pool can store purified rainwater to achieve the effect of reducing rainwater and improve the efficiency of flood control and water management; the purified rainwater can be reused to save water resources.

[0033] 2. The prefabricated matrix filling module ensures the stability of the matrix ratio and avoids the problem of incorrect filling due to on-site construction. At the same time, the prefabricated module saves construction land and is suitable for sponge city construction in mountainous cities. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A diagram of the bioretention pond structure is shown;

[0035] Figure 2 A top view of a bioretention pond is shown;

[0036] Figure 3 A front view of a bioretention pond is shown;

[0037] Figure 4 A schematic diagram of the matrix distribution inside the aerobic tank is shown;

[0038] Figure 5 The internal structure diagram of the mounting part is shown;

[0039] Figure 6 A top view of the interior of the mounting is shown;

[0040] Figure 7 A cover plate structure diagram is shown;

[0041] Figure numerals: anaerobic tank-1, pebble water distribution layer-101, planting layer-102, pyrite layer-103, transition layer-104, gravel layer-105, aerobic tank-2, water collecting tank-3, auxiliary pipe-31, water supply pipe-41, water collecting pipe-42, drainage pipe-43, main pipe-44, ventilation pipe-45, collar-451, L-shaped plate-452, clamp-61, limit groove-611, screw-62, mounting part-7, base-71, first groove-711, second groove-712, third groove-713, locking block-72, avoidance groove-721, cover plate-73, block-731, spring-74. DETAILED DESCRIPTION

[0042] like Figure 1 As shown, this embodiment provides an assembled biological retention pond with nitrogen removal and phosphorus removal functions, including a water collection tank 3 and three modules.

[0043] Specifically, each module includes an anaerobic tank 1 and an aerobic tank 2, and the internal matrix of the anaerobic tank 1 and the aerobic tank 2 is the same, such as Figure 4 As shown, from top to bottom, it includes a pebble water distribution layer 101, a planting layer 102, a pyrite layer 103, a transition layer 104, and a gravel layer 105. At the gravel layer 105, the anaerobic tank 1 and the aerobic tank 2 are connected through a water pipe 41. In other words, Figure 3 , Figure 4As shown, one end of the water pipe 41 is connected to the gravel layer 105 of the anaerobic tank 1, and the other end of the water pipe 41 is connected to the gravel layer 105 of the aerobic tank 2. In order to facilitate the flow of rainwater, the water pipe 41 is inclined downward from the anaerobic tank 1 to the aerobic tank 2. The aerobic tank 2 is connected to the water collecting tank 3 through the water collecting pipe 42. The water collecting pipe 42 is also connected to the gravel layer 105 of the aerobic tank 2, and the water collecting pipe 42 and the water pipe 41 are respectively located on opposite sides of the aerobic tank 2. A ventilation pipe 45 is vertically provided in the aerobic tank 2, and the bottom of the ventilation pipe 45 extends to the gravel layer 105.

[0044] More specifically, the outer walls of the water supply pipe 41 and the water collection pipe 42 are provided with an anti-permeation layer 51, and a waterproof layer 52 is provided on the outside of the anti-permeation layer 51. The anti-permeation layer 51 and the waterproof layer 52 play a protective role to prevent moisture in the soil from penetrating into the water supply pipe 41 or the water collection pipe 42 and causing pollution to the purified rainwater.

[0045] Specifically, Figure 2 , Figure 3 As shown, a drain pipe 43 is installed on the top of one side of the anaerobic tank 1. The drain pipe 43 is used to discharge rainwater into the anaerobic tank 1. A plurality of clamps 61 are installed on the outer wall of the drain pipe 43. Both ends of the clamps 61 are fixedly connected to the edge of the tank by screws 62. A main pipe 44 is installed on the top of one side of the aerobic tank 2. The main pipe 44 is located between the aerobic tank 2 and the water collection tank 3. The main pipe 44 is connected to the municipal rainwater pipe. Two auxiliary pipes 31 are provided in the water collection tank 3. The top of the auxiliary pipe 31 is connected to the main pipe 44. The auxiliary pipe 31 is used to extract water from the water collection tank 3. A plurality of clamps 61 are installed on the outer wall of the main pipe 44. Both ends of the clamps 61 are fixedly connected to the edge of the tank by screws 62.

[0046] More specifically, the matrix filler of the planting layer 102 is a mixture of sandy loam and quartz sand with a volume ratio of 14:86. The planting layer 102 is used to plant plants. In order to ensure the normal growth of plants, the penetration rate of the planting layer 102 is 150 mm / h and the depth is 450 mm.

[0047] More specifically, the matrix filler of the pyrite layer 103 is a mixture of pyrite and quartz sand in a volume ratio of 3:7. The depth of the pyrite layer 103 is 450 mm. The pyrite layer 103 is used to remove nitrogen and phosphorus in rainwater.

[0048] More specifically, the matrix filler of the transition layer 104 is quartz sand, and its particle size is 5%: 10%: 30%: 30%: 25% according to the ratio of 5-10 mesh: 10-20 mesh: 20-30 mesh: 30-60 mesh: 60-140 mesh, respectively. The depth of the transition layer 104 is 100 mm, and the depth of the gravel layer 105 is 100 mm. The transition layer 104 is used to intercept impurities in rainwater to prevent impurities from entering the water supply pipe 41 or the water collection pipe 42.

[0049] One working principle is: the water collecting pipe 42 is in a closed state, and the three drainage pipes 43 discharge rainwater into the corresponding anaerobic pool 1; the rainwater in the anaerobic pool 1 flows through the pebble water distribution layer 101, the planting layer 102, the pyrite layer 103, the transition layer 104, and the gravel layer 105 in turn. After the anaerobic pool 1 performs primary purification treatment on the rainwater, the rainwater flows into the gravel layer 105 of the aerobic pool 2 through the water pipe 41; because the water collecting pipe 42 is in a closed state, the rainwater level in the aerobic pool 2 gradually rises to the pebble water distribution layer 10 1. The rainwater stored in the aerobic pool 2 not only has a flood-fighting effect, but also helps to purify the rainwater; after the aerobic pool 2 performs secondary purification on the rainwater, the water collecting pipe 42 is in an open state, and the rainwater in the aerobic pool 2 flows into the water collecting pool 3 through the water collecting pipe 42; the water collecting pool 3 can store the purified rainwater to achieve the effect of reducing the amount of rainwater and improve the efficiency of flood prevention and water management; the purified rainwater can be reused to save water resources; the rainwater in the water collecting pool 3 can also be pumped to the main pipe 44 through the auxiliary pipe 31, and finally flow into the municipal rainwater pipe.

[0050] In actual application, the number of modules is determined according to the local rainfall conditions and the construction range:

[0051] S1. Determine the shape, area and depth of the bioretention pond according to local rainfall conditions, soil nitrogen and phosphorus pollution, and the construction scope of the mountainous terrain reduction area;

[0052] S2. Determine the number of modules in the bioretention pond and the ratio of the internal matrix of anaerobic tank 1 and aerobic tank 2 according to the local rainfall conditions and soil nitrogen and phosphorus pollution.

[0053] If the vent pipe 45 is simply inserted vertically into the aerobic pool 2, there may be a problem that the vent pipe 45 falls over or shifts up and down. Therefore, the vent pipe 45 of this embodiment is fixedly connected to the clamp 61 on the outer wall of the main pipe 44 through the mounting member 7. The specific implementation method is as follows:

[0054] like Figure 1 , Figure 5-Figure 7As shown, a collar 451 is fixedly provided on the outer wall of the vent pipe 45, an L-shaped plate 452 is provided on the outer wall of the collar 451, and the longitudinal section of the L-shaped plate 452 is connected to the collar 451, the mounting member 7 comprises a base 71, a locking block 72 and a cover plate 73, the base 71 is fixedly provided on the edge of the pool or on the end surface of the first end of the clamp 61, and three interconnected first grooves 711, second grooves 712 and third grooves 713 are provided on the top of the base 71, and in the top view of the base 71, the three grooves are arranged in a "earth" shape, wherein the long axis of the first groove 711 is parallel to the long axis of the main pipe 44, the second groove 712 and the third groove 713 are parallel to each other, and the ends of the second groove 712 and the third groove 713 both pass through the side wall of the base 71, and the locking block 72 slides It is arranged in the first groove 711, the first end of the locking block 72 is located in the third groove 713, and the first end of the locking block 72 is semicircular, the second end of the locking block 72 is connected to the base 71 through a spring 74, and an avoidance groove 721 is provided on the top of the locking block 72. In the direction along the second groove 712, the avoidance groove 721 penetrates the locking block 72, the L-shaped plate 452 is assembled in the second groove 712, and the longitudinal section of the L-shaped plate 452 passes through the avoidance groove 721, there is a gap between the longitudinal section of the L-shaped plate 452 and the first end of the locking block 72, the right-angle portion of the L-shaped plate 452 faces the side of the spring 74, and the right-angle portion hooks the second end of the locking block 72, the cover plate 73 covers the base 71, and the cover plate 73 is connected to the first end of the clamp 61 through a screw 62.

[0055] When the locking block 72 is squeezed by inserting the pin into the third slot 713, the locking block 72 will move toward the spring 74. The spring 74 is compressed, and the cross section of the L-shaped plate 452 loses the restriction of the second end of the locking block 72. Then, the L-shaped plate 452 can be taken out, and disassembly is very convenient.

[0056] When it is necessary to lock the L-shaped plate 452, there are two ways:

[0057] First, when installing the clamp 61, first use a screw 62 to fix the second end of the clamp 61, that is, the end of the clamp 61 away from the mounting member 7. Be careful not to install the cover plate 73. Because the cover plate 73 is not installed, directly put the L-shaped plate 452 into the preset position of the base 71; then cover the cover plate 73, and use another screw 62 to fix the cover plate 73 and the first end of the clamp 61.

[0058] Second, when installing the clamp 61, first use a screw 62 to fix the second end of the clamp 61, that is, the end of the clamp 61 away from the mounting member 7, cover the cover plate 73, and use another screw 62 to fix the cover plate 73 and the first end of the clamp 61. The staff holds the latch and inserts the latch into the third groove 713 to squeeze the locking block 72. The locking block 72 will move toward the spring 74, and the spring 74 is compressed. At this time, the horizontal section of the L-shaped plate 452 is inserted into the second groove 712. After taking out the latch, under the action of the spring 74, the second end of the locking block 72 locks the L-shaped plate 452, and the installation is also very convenient.

[0059] One thing to explain here is that in actual application, each mounting member 7 can be equipped with a latch, which is hung at a preset position by a rope or a chain, such as hanging on the L-shaped plate 452; or all mounting members 7 can share one latch, which is kept by the staff and does not need to be set at the preset position.

[0060] More specifically, in order to further improve the stability of the ventilation pipe 45 , the width of the second groove 712 is consistent with the horizontal size of the L-shaped plate 452 , the top surface of the L-shaped plate 452 is close to the cover plate 73 , and the horizontal section of the L-shaped plate 452 is close to the end surface of the first end of the clamp 61 .

[0061] More specifically, in order to further improve the stability of the cover plate 73 , a limiting groove 611 is provided at the top of the first end of the clamp 61 , and a block 731 is provided on the side of the cover plate 73 facing the clamp 61 , and the block 731 matches in the limiting groove 611 .

[0062] The above embodiments are only used to illustrate the technical ideas and features of the present invention, and are not intended to be the only or limit the present invention. It should be understood by those skilled in the art that various changes or equivalent substitutions made to the present invention without departing from the scope of the present invention all fall within the scope of protection of the present invention.

Claims

1. An assembled biological retention pond with nitrogen and phosphorus removal functions, characterized in that: It includes a water collection tank (3) and a plurality of modules; Each module comprises an anaerobic tank (1) and an aerobic tank (2), the internal matrix of the two being the same, and including, from top to bottom, a pebble water distribution layer (101), a planting layer (102), a pyrite layer (103), a transition layer (104), and a gravel layer (105). At the gravel layer (105), the two are connected via a water delivery pipe (41), and the aerobic tank (2) is connected to the water collection tank (3) via a water collection pipe (42). A ventilation pipe (45) is vertically provided in the aerobic tank (2), and the ventilation pipe (45) extends to the gravel layer (105); A drainage pipe (43) is installed on the top of one side of the anaerobic tank (1) for draining rainwater into the anaerobic tank (1). A main pipe (44) is installed on the top of one side of the aerobic tank (2). The main pipe (44) is connected to a municipal rainwater pipe. A plurality of auxiliary pipes (31) are installed in the water collection tank (3). The top of the auxiliary pipes (31) is connected to the main pipe (44) for extracting water from the water collection tank (3). A plurality of clamps (61) are installed on the outer wall of the main pipe (44). Both ends of the clamps (61) are fixedly connected to the edge of the tank by screws (62). The ventilation pipe (45) is fixedly connected to the clamps (61) on the outer wall of the main pipe (44) by a mounting member (7). A collar (451) is fixedly provided on the outer wall of the vent pipe (45), and an L-shaped plate (452) is provided on the outer wall of the collar (451). The mounting member (7) comprises a base (71), a locking block (72) and a cover plate (73). The base (71) is fixedly provided on the edge of the pool, and the top of the base (71) is provided with three interconnected first grooves (711), a second groove (712) and a third groove (713). In a top view of the base (71), the three grooves are arranged in a "earth" shape, wherein the long axis of the first groove (711) is parallel to the long axis of the main pipe (44), and the ends of the second groove (712) and the third groove (713) both penetrate the side wall of the base (71), and the locking block (72) is slidably provided in the first groove (711). The locking block (72) is slidably provided in the first groove (711). One end of the tightening block (72) is located in the third groove (713), and the end is semicircular. The other end of the locking block (72) is connected to the base (71) through a spring (74). An avoidance groove (721) is provided on the top of the locking block (72). The L-shaped plate (452) is assembled in the second groove (712), and the longitudinal section of the L-shaped plate (452) passes through the avoidance groove (721). The right angle portion of the L-shaped plate (452) faces the spring (74) side, and the right angle portion hooks the locking block (72). The cover plate (73) covers the base (71) and is connected to the first end of the clamp (61) through a screw (62). When a latch is inserted into the third groove (713) to squeeze the locking block (72), the cover plate (73) is used to unlock the L-shaped plate (452).

2. The assembled biological retention pond with nitrogen and phosphorus removal function according to claim 1 is characterized in that: The width of the second groove (712) is consistent with the size of the transverse section of the L-shaped plate (452), the top surface of the L-shaped plate (452) is in close contact with the cover plate (73), and the transverse section of the L-shaped plate (452) is in close contact with the end surface of the clamp (61).

3. The assembled biological retention pond with nitrogen and phosphorus removal function according to claim 2 is characterized in that: A limiting groove (611) is provided at the top of the first end of the clamp (61), and a block (731) is provided on the side of the cover plate (73) facing the clamp (61), and the block (731) matches in the limiting groove (611).

4. The assembled biological retention pond with nitrogen and phosphorus removal function according to claim 1 is characterized in that: In the direction from the anaerobic tank (1) to the aerobic tank (2), the water delivery pipe (41) is arranged to be inclined downward.

5. The assembled biological retention pond with nitrogen and phosphorus removal function according to claim 1 is characterized in that: The outer walls of the water delivery pipe (41) and the water collection pipe (42) are both provided with an anti-permeability layer (51) and a waterproof layer (52), and the anti-permeability layer (51) is located on the inner side of the waterproof layer (52).

6. The assembled biological retention pond with nitrogen and phosphorus removal function according to claim 1 is characterized in that: The matrix filler of the planting layer (102) is a mixture of sandy loam and quartz sand, with a volume ratio of 14-17:86-83. The infiltration rate of the planting layer (102) is not less than 150 mm / h, and the depth is not less than 450 mm.

7. The assembled biological retention pond with nitrogen and phosphorus removal function according to claim 1 is characterized in that: The matrix filler of the pyrite layer (103) is a mixture of pyrite and quartz sand with a volume ratio of 2~3:8~7. The depth of the pyrite layer (103) is 450mm~550mm.

8. The assembled biological retention pond with nitrogen and phosphorus removal function according to claim 1 is characterized in that: The matrix filler of the transition layer (104) is quartz sand, and its particle size is 5%: 10%: 30%: 30%: 25% of 5-10 mesh: 10-20 mesh: 20-30 mesh: 30-60 mesh: 60-140 mesh, respectively. The depth of the transition layer (104) is not less than 100 mm.

9. The assembled biological retention pond with nitrogen and phosphorus removal function according to claim 1, characterized in that: The horizontal area of ​​the module is 1000mm×1000mm.

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