A three-stage sedimentation and filtration rural sewage centralized treatment system

Abstract

The patent of the present invention discloses a three-stage sedimentation and filtration rural sewage centralized treatment system, which specifically relates to the technical field of sewage treatment systems. A three-stage sedimentation and filtration rural sewage centralized treatment system includes three foundation pits built according to the terrain difference, the inner wall of each foundation pit is cast with a concrete cushion layer, and the three foundation pits are sequentially provided with staggered first-stage filter ports, second-stage filter ports, third-stage filter ports and discharge ports, the first-stage filter ports are provided with gabions filled with sand and gravel of different grades, the second-stage filter ports are provided with a geotextile layer, the geotextile layer is folded from multiple geotextiles, and the third-stage filter ports are provided with a biofilm. The technical solution of the present invention solves the problem of difficult sewage treatment in remote rural areas, and can be used for sewage treatment in rural areas.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment systems, and in particular to a three-stage sedimentation and filtration rural sewage centralized treatment system. Background Art

[0002] A complete rural sewage treatment facility system includes indoor sanitary facilities, outdoor drainage facilities and sewage treatment facilities. The first two facilities have been renovated in many rural areas and have been partially built, such as household flush toilets and sewage pipes for discharge. However, sewage treatment facilities are basically not built in remote rural areas, and they are still discharged into large sewage pools or infiltration pits. Such facilities correspond to personal hygiene needs, village environmental needs and public environmental needs respectively. They cannot be separated in isolation. Only when they form an organic whole can the best sewage treatment effect be guaranteed. It can be seen that the sewage treatment facilities at the end are the shortcomings of many rural areas.

[0003] If sewage treatment facilities similar to those in towns are used to comprehensively treat rural sewage, it is currently unrealistic to implement it in remote rural areas due to the large amount of work, high structural requirements, complex construction, high maintenance costs, and high personnel quality requirements. Therefore, there is an urgent need for a sewage treatment facility that is low-cost to build, simple to maintain, and does not require fixed management personnel. Summary of the invention

[0004] The present invention aims to provide a three-stage sedimentation and filtration rural sewage centralized treatment system, which solves the problem of difficult sewage treatment in remote rural areas.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present invention is as follows: a three-stage sedimentation and filtration rural sewage centralized treatment system, comprising three foundation pits built according to the terrain difference, the inner wall of each foundation pit is poured with a concrete cushion layer, and the three foundation pits are sequentially provided with a first-stage filter port, a second-stage filter port, a third-stage filter port and a discharge port arranged in a staggered manner, a gabion stone cage is provided at the first-stage filter port, and the gabion stone cage is filled with sand and gravel of different grades, a geotextile layer is provided at the second-stage filter port, and the geotextile layer is formed by folding multiple geotextiles, and a biofilm is provided at the third-stage filter port.

[0006] Preferably, each of the foundation pits is provided with a sediment collecting mechanism, and the sediment collecting mechanism includes a cylinder, a cleaning plate and a sewage door hinged on one side of the foundation pit, the cleaning plate is slidably connected to the bottom of the foundation pit, a rubber plate is obliquely arranged on the cleaning plate, a sewage outlet is opened at the foundation pit corresponding to the sewage door, and a plurality of limiting mechanisms are provided on the sewage door, each of the limiting mechanisms includes a control box, a trigger rod and a limiting magnet, the control box is buried in the foundation pit directly below the sewage outlet, a first rotating shaft is rotatably connected to the control box, the first rotating shaft is provided with a gear and a trigger magnet, and the first A torsion spring is connected between a rotating shaft and a control box, the trigger rod passes through a foundation pit and the top of the control box, the trigger rod is slidably connected to the foundation pit, the top of the trigger rod is symmetrically provided with wedge surfaces, the wedge surfaces of the trigger rod are located on the movement trajectory of the cleaning plate, the trigger rod is provided with spur teeth meshing with gears, the limit magnet is slidably connected to the sewage door, a slideway for the limit magnet to slide is provided in the sewage door, a first reset spring is connected between the limit magnet and the slide, the limit magnet and the trigger magnet repel each other, and the foundation pit is also provided with slots located on the movement trajectory of the limit magnet.

[0007] Through the above arrangement, the sewage door is limited by the mutual attraction between the limit magnet and the trigger magnet, thereby avoiding the sewage door from being opened due to water pressure. When cleaning the sediment, the cylinder is used to push the cleaning plate to move to clean the sediment accumulated at the bottom of the foundation pit. When the cleaning plate pushes the trigger rod to drive the first rotating shaft to rotate, the first rotating shaft rotates so that the trigger magnet and the limit magnet are located on the same straight line, so that a repulsive force is generated between the two. The repulsive force is used to move the limit magnet out of the slot, thereby releasing the limiting effect on the sewage door. Finally, the cleaning plate and the sediment push the sewage door open to clean the sediment, thereby improving the sewage treatment effect of this scheme and reducing the frequency of foundation pit cleaning.

[0008] Preferably, a baffle is obliquely provided on one side of the cleaning plate.

[0009] Through the above arrangement, the baffle is used to facilitate the cleaning of the sediment at the bottom of the foundation pit, and it is also convenient to open the sewage door, thereby improving the efficiency of clearing the sediment.

[0010] Preferably, each of the foundation pits is further provided with a collecting box at the sewage outlet, a sieve plate is provided in the collecting box, a plurality of water filtering holes are opened on the sieve plate, and a water permeable membrane is provided on each of the water filtering holes.

[0011] Through the above-mentioned arrangement, the collection box is used to collect sediment and sewage, thus avoiding secondary pollution to the environment. At the same time, the sediment and sewage are separated, which is convenient for comprehensive treatment of sediment and sewage and reduces the cost of subsequent treatment.

[0012] Preferably, each of the cylinders is also provided with an automatic trigger mechanism, which includes a funnel-shaped drain pipe, a second rotating shaft rotatably connected to the smaller side of the opening on the drain pipe, and an air pump, the drain pipe is respectively arranged at the first-stage filter port, the second-stage filter port and the third-stage filter port, the second rotating shaft is coated with a water wheel, the second rotating shaft is rotatably connected to a cam, the handle of the air pump is located on the movement track of the cam, the air pump is fixedly installed on the top of the foundation pit, the air pump is connected to an air pipe, the air pipe is connected to an air storage box, a slide plate and a first pressure sensor located on the movement track of the slide plate are provided in the air storage box, the slide plate is slidably connected to the air storage box, a second return spring is connected between the slide plate and the air storage box, the first pressure sensor is located on the side away from the air pipe, a second pressure sensor located on the movement track of the rubber plate is also provided on the side wall of the foundation pit, the first pressure sensor and the second pressure sensor are both electrically connected to the cylinder, a nozzle close to the air pipe is also provided on the top of the air storage box, and a pressure valve is provided on the nozzle.

[0013] Through the above arrangement, the second rotating shaft can be driven to rotate by the drainage pipe and the water wheel. After the second rotating shaft rotates, the air storage box can be intermittently inflated through the cam and the air pump, so that the slide plate slides in the air storage box and touches the first pressure sensor. At this time, the first pressure sensor starts the cylinder to start cleaning. When the rubber plate touches the second pressure sensor, the cylinder resets, realizing the regular cleaning of sediment, thereby reducing the labor intensity of management personnel, realizing automated operation, and further reducing the cost of sewage treatment.

[0014] Compared with the prior art, this solution has the following beneficial effects:

[0015] 1. This plan is applicable to remote rural areas where agriculture, animal husbandry and breeding are the main industries, there is basically no industry, and the wastewater discharged by them contains basically no heavy metals and chemical pollutants.

[0016] 2. This plan adopts a three-stage concrete sedimentation tank with simple structure, low cost, easy maintenance and long service life.

[0017] 3. This scheme can ensure that solid pollutants are basically precipitated through three-stage concrete sedimentation tanks, which can be removed regularly and eliminate the need for daily maintenance;

[0018] 4. This scheme innovates the three-stage filtration, which is a technical means to gradually improve the water quality. First, large particles in the solid insoluble matter are removed through the sand and gravel filter port; second, fine particles in the solid insoluble matter are removed through the geotextile filter port; finally, harmful components in the sewage are adsorbed and removed through biological filtration technology, that is, geotextile wrapped with sand and gravel fillers containing decomposing bacteria. Through the above three-stage sedimentation and three-stage filtration, the water quality of this type of rural sewage can be greatly improved, basically meeting the requirements for irrigating grasslands and farmland. At the same time, this scheme is not only low-cost, but also does not require special management, simplifies maintenance methods, reduces maintenance costs, and realizes simple, efficient and low-cost sewage treatment in remote rural areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A top view of a three-stage sedimentation and filtration rural sewage centralized treatment system according to the present invention;

[0020] Figure 2 for Figure 1 Sectional view of AA in the middle;

[0021] Figure 3 for Figure 2 A partial enlarged view of point B in the middle;

[0022] Figure 4 for Figure 2 A magnified partial view of point C in the middle. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below through specific embodiments:

[0024] The figure marks in the drawings of the specification include: foundation pit 1, first-stage filter port 2, second-stage filter port 3, third-stage filter port 4, discharge port 5, cylinder 6, cleaning plate 7, sewage door 8, waterproof shell 9, control switch 10, baffle 11, rubber plate 12, control box 13, trigger rod 14, limit magnet 15, first rotating shaft 16, gear 17, trigger magnet 18, torsion spring 19, first return spring 20, slot 21, collection box 22, first sealing plate 23, second sealing plate 24, sieve plate 25, drain pipe 26, second rotating shaft 27, water wheel 28, air pump 29, driven shaft 30, cam 31, third return spring 32, air pipe 33, air storage box 34, adjusting rod 35, movable plate 36, fixed plate 37, slide plate 38, first pressure sensor 39, second return spring 40, second pressure sensor 41.

[0025] Example 1

[0026] As attached Figures 1 to 4As shown: A three-stage sedimentation and filtration rural sewage centralized treatment system, including three foundation pits 1 built according to the terrain difference. The inner wall of each foundation pit 1 is poured with a 20cm concrete cushion. The bottom of the foundation pit 1 is leveled before pouring concrete. The strength grade of the concrete is C10. The concrete layer can ensure that the foundation pit 1 will not settle unevenly during the subsequent work process. The three foundation pits 1 are opened from left to right in a staggered manner with the first-stage filter port 2, the second-stage filter port 3, the third-stage filter port 4 and the discharge port 5. A gabion cage is placed at the first-stage filter port 2. The gabion cage is filled with sand and gravel of different grades to control its permeability coefficient at K×10 -1 cm / s; a geotextile layer is provided at the second-stage filter port 3. The geotextile layer is folded from multiple geotextiles, and its permeability coefficient is controlled at K×10 -1 cm / s~K×10 -2 cm / s; a biofilm is arranged at the third filter port 4, which is arranged in a manner that clean sand and gravel fillers are wrapped in geotextiles, and the biofilm is fixed outside the clean sand and gravel fillers. The above structure is used to achieve the purpose of biological contact oxidation and purification. The permeability coefficient of the clean sand and gravel fillers wrapped in geotextiles is controlled at K×10 -1 cm / s~K×10 -2 cm / s is enough.

[0027] Each foundation pit 1 is provided with a sediment collection mechanism, which includes a cylinder 6, a cleaning plate 7 and a sewage door 8 hinged on one side of the foundation pit 1. The cylinder 6 is bolted to the bottom of the foundation pit 1, and each cylinder 6 is located on the side of the corresponding foundation pit 1 away from the first-stage filter port 2, the second-stage filter port 3 or the third-stage filter port 4. The cylinder 6 is covered with a waterproof shell 9, and the piston rod of the cylinder 6 passes through the shell and is slidably sealed with the shell. A maintenance port is opened on the foundation pit 1 on the side where the cylinder 6 is located. The cylinder 6 is also electrically connected to a control switch 10 installed on the top of the foundation pit 1, and the control switch 10 is located on one side of the sewage door 8. The cleaning plate 7 is fixed to the piston rod of the cylinder 6, and the cleaning plate 7 is slidably connected to the bottom of the foundation pit 1. The length of the cleaning plate 7 is equal to the length of the foundation pit 1. A baffle 11 and a rubber plate 12 located directly above the baffle 11 are obliquely arranged on the side of the cleaning plate 7 away from the cylinder 6. A wedge surface matching the bottom of the foundation pit 1 is provided at the bottom of the baffle 11. The baffle 11 is slidably connected to the foundation pit 1. The rubber plate 12 is connected to the cleaning plate 7 through a spring hinge. The width of the rubber plate 12 is greater than the width of the baffle 11. The orthographic width of the rubber plate 12 is greater than the distance between the trigger rod 14 and the inner wall of the foundation pit 1 on the side where the sewage door 8 is located plus the orthographic width of the baffle 11. A wedge surface matching the inner wall of the foundation pit 1 is provided on the rubber plate 12. The rubber plate 12 is slidably connected to the inner wall of the foundation pit 1.

[0028] The sewage door 8 is connected to the foundation pit 1 by a spring hinge. The sewage door 8 is located at the bottom of the side wall of the corresponding foundation pit 1 near the first-stage filter port 2, the second-stage filter port 3 or the third-stage filter port 4. A sewage outlet is provided at the foundation pit 1 corresponding to the sewage door 8. The sewage door 8 is provided with a plurality of spaced limiting mechanisms, each of which includes a control box 13, a trigger rod 14 and a limiting magnet 15. The control box 13 is buried in the foundation pit 1 directly below the corresponding sewage outlet, and a maintenance door is hinged on one side of the control box 13. A first rotating shaft 16 is rotatably connected in the control box 13, and a gear 17 and a trigger magnet 18 are arranged on the first rotating shaft 16. A torsion spring 19 is connected between the first rotating shaft 16 and the control box 13. The trigger rod 14 passes through the concrete cushion layer, the foundation pit 1 and the top of the control box 13. The trigger rod 14 is slidably connected to the foundation pit 1. The top of the trigger rod 14 is symmetrically provided with wedge surfaces. Each wedge surface of the trigger rod 14 is located on the motion track of the cleaning plate 7. The trigger rod 14 is provided with straight teeth meshing with the gear 17. The limiting magnet 15 is slidably connected in the sewage discharge door 8. A wedge surface cooperating with the card slot 21 is provided on the side of the limiting magnet 15 close to the cleaning plate 7. A slideway for the corresponding limiting magnet 15 to slide is provided inside the sewage door 8, and a first reset spring 20 is connected between the limiting magnet 15 and the slideway. The magnetic poles of the limiting magnet 15 and the trigger magnet 18 are opposite. A slot 21 located on the movement trajectory of the limiting magnet 15 is also provided on the foundation pit 1. When the first reset spring 20 does not generate elastic force, the limiting magnet 15 is clamped in the slot 21, and the trigger magnet 18 is located on the lower side of the first rotating shaft 16, and no repulsive force is generated between the limiting magnet 15 and the trigger magnet 18.

[0029] Each foundation pit 1 is also provided with a collection box 22 located on one side of the sewage outlet. The top of the collection box 22 is provided with an opening, and a first sealing plate 23 is hinged at the opening, one side of which is against the outer wall of the foundation pit 1. A second sealing plate 24 is connected between the first sealing plate 23 and the collection box 22. The top of the collection box 22 can be sealed with the help of the first sealing plate 23 and the second sealing plate 24, ensuring that the odor will not be emitted during the sediment collection process, thereby avoiding pollution to the environment. A through groove is provided on the side of the collection box 22 close to the maintenance door, so that the maintenance door can be opened to repair and maintain the components in the control box 13. A sieve plate 25 located below the through groove is also embedded in the collection box 22. The sieve plate 25 is tilted in the collection box 22, and the height of the sieve plate 25 gradually decreases from one side close to the through groove to the other side. A plurality of water filtering holes are provided on the sieve plate 25, and a water-permeable membrane is provided on each water filtering hole.

[0030] During operation, sewage enters the foundation pit 1 from the first filter port 2, and some solid insolubles in the sewage fall to the bottom of the foundation pit 1 through natural sedimentation. At the same time, the large solid insoluble particles in the sewage are removed by means of sand and gravel filled with different grades in the gabion stone cage; the small solid insoluble particles in the sewage are removed through the geotextile layer, and the harmful components of the sewage are adsorbed by the biofilm. The above-mentioned three-stage sedimentation and three-stage filtration can greatly improve the water quality of this type of rural sewage and meet the requirements of irrigating grasslands and farmland.

[0031] After a period of natural sedimentation, some fixed impurities are accumulated at the bottom of each foundation pit 1. At this time, the control switch 10 is used to turn on the cylinder 6, which pushes the cleaning plate 7 to move toward the sewage discharge door 8 through the piston rod, and the solid impurities at the bottom of the foundation pit 1 are pushed to the side of the sewage discharge door 8 through the baffle 11. Before the baffle 11 pushes the trigger rod 14 to move downward, the rubber plate 12 abuts against the inner wall of the foundation pit 1, so that the area enclosed by the rubber plate 12, the cleaning plate 7 and the baffle 11 can be separated from the sewage above the rubber plate 12 by the rubber plate 12. And in the process of the cleaning plate 7 continuing to move, the rubber plate 12 slides on the inner wall under the action of its wedge surface and always keeps against the inner wall of the foundation pit 1. When the baffle 11 pushes the trigger rod 14 to move downward, the trigger rod 14 can drive the first rotating shaft 16 to rotate through the spur gear and the gear 17, so that the trigger magnet 18 rotates to the upper side of the first rotating shaft 16 and faces the limit magnet 15, and the limit magnet 15 is pushed out of the slot 21 by the repulsive force generated by the trigger magnet 18 and the limit magnet 15. Since the cylinder 6 is still pushing the cleaning plate 7 to move, the solid insolubles and the baffle 11 push the sewage door 8 to open, so that part of the sewage and the fixed insolubles deposited at the bottom of the foundation pit 1 fall into the collection box 22 to collect the solid insolubles, and the sieve plate 25 and the permeable membrane are used to separate the solid insolubles and sewage. When the baffle 11 is separated from the trigger rod 14, the first rotating shaft 16 is reset under the action of the torsion spring 19.

[0032] When the cleaning plate 7 is close to the inner wall of the foundation pit 1, the control switch 10 is used to reset the piston rod of the cylinder 6. During the resetting process of the piston rod of the cylinder 6, the rubber plate 12 is always in contact with the inner wall of the foundation pit 1, so that the area enclosed by the rubber plate 12, the cleaning plate 7 and the baffle plate 11 is separated from the sewage above the rubber plate 12, so that when the baffle plate 11 pushes the trigger rod 14 to push the limiting magnet 15 out of the slot 21 again, it can also maintain separation from the sewage, thereby avoiding the sewage door 8 from opening under the action of sewage pressure, thereby maintaining the stability of this solution.

[0033] Example 2

[0034] The difference between this embodiment and the first embodiment is that each cylinder 6 of this embodiment is also provided with an automatic trigger mechanism, which includes a funnel-shaped drain pipe 26, a second rotating shaft 27 rotatably connected to the side with a smaller opening of the drain pipe 26, and a second rotating shaft 28 connected to the drain pipe 26. and an air pump 29, the drain pipe 26 is respectively arranged at the first-stage filter port 2, the second-stage filter port 3 and the third-stage filter port 4, the second rotating shaft 27 is covered with a waterwheel 28, the waterwheel 28 is used for power generation or farmland irrigation in the prior art, an opening for the waterwheel 28 to rotate is opened on the drain pipe 26, a driven shaft 30 passing through the drain pipe 26 is coaxially connected to the second rotating shaft 27, a cam 31 is rotatably connected to the driven shaft 30, the air pump 29 is a device for pumping or inflating in the prior art, the air pump 29 is located just above the collecting box 22 on the side close to the waterwheel 28, the air pump 29 is fixedly connected to the outer wall of the foundation pit 1 through a support rod, the handle of the air pump 29 is located on the motion trajectory of the cam 31, and a third reset spring 32 is connected between the handle of the air pump 29 and the cylinder body. The air outlet of the air pump 29 is connected to an air pipe 33, and the air pipe 33 is connected to an air storage box 34. An adjusting port is provided on the air storage box 34 at a side away from the air pipe 33. An adjusting rod 35 passing through the air storage box 34 is slidably connected in the adjusting port. A movable plate 36 located in the air storage box 34 is fixedly connected to the adjusting rod 35, and the movable plate 36 is slidably and hermetically connected to the air storage box 34. A fixing plate 37 located outside the air storage box 34 is also provided on the adjusting rod 35, and the fixing plate 37 is bolted to the air storage box 34. A supporting plate is welded to the bottom of the air storage box 34, and the supporting plate is bolted to the outer wall of the foundation pit 1. A slide plate 38 and a first pressure sensor 39 located on the motion track of the slide plate 38 are provided in the air storage box 34, and the slide plate 38 is slidably and hermetically connected to the air storage box 34. A second return spring 40 is connected between the slide plate 38 and the air storage box 34, and the first pressure sensor 39 is installed on the movable plate 36. The air storage box 34 is also connected to a nozzle near the air pipe 33, and a pressure valve is installed in the nozzle. A second pressure sensor 41 is also provided on the side wall of the foundation pit 1, which is located on the movement track of the rubber plate 12. The second pressure sensor 41 is installed on the inner wall of the foundation pit 1 on one side of the sewage discharge door 8. The first pressure sensor 39 and the second pressure sensor 41 are both electrically connected to the cylinder 6.

[0035] When working, workers are no longer required to operate. The sewage flowing out of the first-stage filter port 2, the second-stage filter port 3 or the third-stage filter port 4 drives the water wheel 28 to rotate, and the drain pipe 26 helps to collect the sewage. When the water wheel 28 rotates, it can drive the second rotating shaft 27 and the driven shaft 30 to rotate, and then use the cam 31 on the driven shaft 30 to realize the intermittent pumping of the air pipe 33 by the air pump 29, and the third reset spring 32 helps the rapid reset of the handle of the air pump 29 to maintain the stability of the pumping process. When the air pipe 33 is continuously filled with air, the air enters the enclosed space between the slide plate 38 and the air storage box 34 near the side of the air pipe 33 along the air pipe 33, and uses the air to push the slide to move to the other side. When the slide plate 38 touches the first pressure sensor 39, the pressure of the enclosed space on the side of the slide plate 38 in the air storage box 34 reaches the preset value of the pressure valve, so that the air is discharged by the pressure valve. When the first pressure sensor 39 is touched, the cylinder 6 can be triggered, and the cylinder 6 starts cleaning work by using the cleaning plate 7. Its working process is the same as that in Example 1. When the rubber plate 12 touches the second pressure sensor 41, the cleaning plate 7 is located at the side wall of the foundation pit 1 and is against it. When the second pressure sensor 41 is touched, the cylinder 6 is triggered, and the piston rod of the cylinder 6 starts to reset. The working process when the piston rod of the cylinder 6 is reset is also the same as that in Example 1.

[0036] The position of the first pressure sensor 39 can be adjusted by using the fixed plate 37, the adjusting rod 35 and the movable plate 36. At the same time, by replacing different pressure valves, the triggering interval time of the cylinder 6 can be controlled, so that adaptive adjustments can be made according to different sewage discharge cycles and rules, thereby improving the application scope and rationality of this solution.

[0037] The automatic cleaning and collection of solid insolubles is achieved by an automatic triggering mechanism, which reduces the labor intensity of workers and the cost of running the scheme, and is conducive to promotion and application.

[0038] The above are only embodiments of the present invention, and the common knowledge such as the known specific structures and / or characteristics in the scheme are not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A three-stage sedimentation and filtration rural sewage centralized treatment system, characterized by: The invention comprises three foundation pits built according to the terrain difference, the inner wall of each foundation pit is cast with a concrete cushion layer, the three foundation pits are provided with a first-level filter port, a second-level filter port, a third-level filter port and a discharge port arranged in a staggered manner in sequence, a gabion stone cage is provided at the first-level filter port, and the gabion stone cage is filled with sand and gravel of different grades, a geotextile layer is provided at the second-level filter port, and the geotextile layer is formed by folding a plurality of geotextiles, and a biofilm is provided at the third-level filter port; Each of the foundation pits is provided with a sediment collection mechanism, which includes a cylinder, a cleaning plate and a sewage discharge door hinged on one side of the foundation pit; Each of the cylinders is also provided with an automatic trigger mechanism, which includes a funnel-shaped drain pipe, a second rotating shaft rotatably connected to the smaller side of the opening on the drain pipe, and an air pump, the drain pipe is respectively arranged at the first-stage filter port, the second-stage filter port and the third-stage filter port, the second rotating shaft is coated with a water wheel, the second rotating shaft is rotatably connected to a cam, the handle of the air pump is located on the movement track of the cam, the air pump is fixedly installed on the top of the foundation pit, the air pump is connected to an air pipe, the air pipe is connected to an air storage box, a slide plate and a first pressure sensor located on the movement track of the slide plate are provided in the air storage box, the slide plate is slidably connected to the air storage box, a second return spring is connected between the slide plate and the air storage box, the first pressure sensor is located on the side away from the air pipe, a second pressure sensor located on the movement track of the rubber plate is also provided on the side wall of the foundation pit, the first pressure sensor and the second pressure sensor are both electrically connected to the cylinder, a nozzle close to the air pipe is also provided on the top of the air storage box, and a pressure valve is provided on the nozzle.

2. A three-stage sedimentation and filtration rural sewage centralized treatment system according to claim 1, characterized in that: The cleaning plate is slidably connected to the bottom of the foundation pit, and a rubber plate is obliquely arranged on the cleaning plate. A sewage outlet is opened at the foundation pit corresponding to the sewage discharge door, and a plurality of limiting mechanisms are arranged on the sewage discharge door, each of which includes a control box, a trigger rod and a limiting magnet. The control box is buried in the foundation pit just below the sewage outlet, and a first rotating shaft is rotatably connected in the control box, and a gear and a trigger magnet are arranged on the first rotating shaft. A torsion spring is connected between the first rotating shaft and the control box, and the trigger rod passes through the foundation pit and the top of the control box. The trigger rod is slidably connected to the foundation pit, and a wedge surface is symmetrically arranged on the top of the trigger rod. The wedge surface of the trigger rod is located on the motion track of the cleaning plate, and the trigger rod is provided with a straight tooth meshing with the gear. The limiting magnet is slidably connected in the sewage discharge door, and a slideway for sliding the limiting magnet is opened in the sewage discharge door. A first reset spring is connected between the limiting magnet and the slideway, and the limiting magnet and the trigger magnet repel each other. A card slot located on the motion track of the limiting magnet is also spaced apart on the foundation pit.

3. A three-stage sedimentation and filtration rural sewage centralized treatment system according to claim 2, characterized in that: A baffle is obliquely arranged on one side of the cleaning plate.

4. A three-stage sedimentation and filtration rural sewage centralized treatment system according to claim 3, characterized in that: Each of the foundation pits is also provided with a collecting box at the sewage outlet, a sieve plate is provided in the collecting box, a plurality of water filtering holes are opened on the sieve plate, and a water permeable membrane is provided on each of the water filtering holes.

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