Landfill leachate pretreatment equipment and method

Abstract

The invention relates to the field of water treatment, and discloses landfill leachate pretreatment equipment and method.The landfill leachate pretreatment equipment comprises a sand filter tank, an adjusting tank and a guide pipe fixedly connected between the sand filter tank and the adjusting tank, the two sides of the sand filter tank are fixedly connected with a water inlet pipe and a blow-off pipe respectively, and the bottom of the sand filter tank is fixedly connected with a backwashing pipe; a uniform spraying assembly for uniformly spraying the landfill leachate on the surfaces of the gravels is arranged in the sand filtering tank; the uniform sprinkling assembly comprises a suspension pipe arranged at the top end in the sand filter tank, and the water inlet pipe penetrates through the sand filter tank and extends to be communicated with the suspension pipe; impact of landfill leachate on gravel is reduced through shunting, the situation that the filtering effect is affected due to the fact that the gravel is scattered is avoided, the shunted landfill leachate is evenly sprayed on the surface of the gravel, it is ensured that the landfill leachate is evenly filtered by the gravel, and the situation that the landfill leachate only impacts a local area of the gravel, and consequently blocking is caused by gravel filtering loads in the area is avoided; the backwashing frequency during filtering is reduced, and the filtering efficiency of the landfill leachate is improved.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and more specifically, to a landfill leachate pretreatment device and method. Background Technology

[0002] Landfill leachate treatment technology is an environmental protection technology for purifying high-concentration wastewater generated by landfills and incineration plants. It mainly treats leachate formed by rainwater, the moisture in the waste itself, and degradation products.

[0003] Landfill leachate pretreatment is a crucial step in the treatment process, primarily aimed at removing large suspended solids and adjusting the pH level to reduce the burden on subsequent treatment processes. Core steps include: Physical filtration: Using sand filters, security filters (10-micron precision), and other equipment to effectively intercept particulate impurities and prevent clogging of downstream equipment. Chemical adjustment: Depending on the water quality, adding alkali (such as sodium hydroxide) or sulfuric acid to adjust the pH to a suitable range (e.g., around 7.5) to facilitate subsequent biological treatment or membrane system operation. If the calcium ion concentration in the water is high, lime should be avoided to prevent scaling. After pretreatment, the leachate enters an equalization tank for homogenization of water volume and quality, ensuring stable operation of the subsequent treatment system.

[0004] However, when using a sand filter to filter landfill leachate, the leachate entering the sand filter impacts the sand and gravel inside, causing indentations in the sand at the impact points. Furthermore, when leachate is steadily introduced, the impact points remain essentially unchanged. This means that during filtration, the leachate always permeates downwards from the impact points. On one hand, this reduces the thickness of the sand in the impact area, leading to a decrease in filtration efficiency. On the other hand, the constant permeation area of ​​the leachate results in localized filtration, making the sand prone to clogging. This necessitates increasing the backwashing frequency, further reducing filtration efficiency. Summary of the Invention

[0005] This invention provides a landfill leachate pretreatment device and method, which solves the technical problems in related technologies where landfill leachate injected into the sand filter always impacts the same position, resulting in the sand being impacted and dispersed, reducing the filtration thickness. At the same time, always using a local area for filtration makes the sand prone to clogging, requiring an increase in backwashing frequency and reducing filtration efficiency.

[0006] The present invention provides a landfill leachate pretreatment device, including a sand filter tank, an equalization tank and a conduit fixedly connecting the two. A water inlet pipe and a sewage outlet pipe are fixedly connected to both sides of the sand filter tank, and a backwash pipe is fixedly connected to the bottom of the sand filter tank. The interior of the sand filter tank is provided with a uniform spraying component for uniformly spraying the landfill leachate onto the surface of the sand and gravel. The uniform spraying assembly includes a suspension pipe located at the top of the inside of the sand filter tank. The water inlet pipe passes through the inside of the sand filter tank and extends to connect with the suspension pipe. A diversion pipe is rotatably connected to the bottom of the suspension pipe via a bearing, and a spiral fan blade is fixedly connected inside the diversion pipe. A diversion pipe is fixedly connected to the bottom of the diversion pipe, and a diversion hole is opened on the surface of the diversion pipe.

[0007] As a further optimization of the present invention, the sand filter tank is provided with a backwashing space expansion component. The backwashing space expansion component includes a piston plate movably connected to the inside of the sand filter tank, and a connecting seat is fixedly connected to the bottom of the piston plate through a connecting frame. A pull rod is fixedly connected to the bottom of the connecting seat, and an extension rod is movably connected to the bottom of the pull rod. A first sand trap is movably connected to the inside of the sand filter tank, and a second sand trap is movably connected to the upper end of the first sand trap.

[0008] As a further optimization of the present invention, the number of the second sand traps is two, the pull rod and the extension rod respectively pass through the two second sand traps and are fixedly connected to them, and the extension rod passes through the interior of the pull rod and is fixedly connected to the limit block.

[0009] As a further optimization of the present invention, the second sand trap has an inverted "U" shaped structure that is wider at the top and narrower at the bottom. The two second sand traps are stacked together with the first sand trap. The maximum distance that the extension rod extends out of the pull rod is less than the overlap height of the two second sand traps and the first sand trap. A sensor is fixedly connected to the outside of the suspension tube.

[0010] As a further optimization of the present invention, the sand filter tank is provided with a backwashing auxiliary component. The backwashing auxiliary component includes a deflector tube fixedly connected to the top of the connecting seat, and the surface of the deflector tube is provided with a liquid inlet. The top of the deflector tube is movably connected to a baffle plate through a spring hinge. The pull rod and the extension rod are both fixedly connected to a stirring rod.

[0011] As a further optimization of the present invention, a locking block is fixedly connected to the surface of the deflector, the top of the deflector extends into the interior of the drainage tube, and a locking groove adapted to the locking block is provided on the inner wall of the drainage tube.

[0012] As a further optimization of the present invention, the sand filter tank is provided with an auxiliary sewage discharge component. The auxiliary sewage discharge component includes a sewage inlet on the surface of the stirring rod on the extension rod. The stirring rod is connected to the extension rod. The pull rod has a sewage discharge chamber inside and a sewage discharge port on its surface.

[0013] As a further optimization of the present invention, the diameter of the inlet port on the surface of the stirring rod decreases from top to bottom, and the diameter of the inlet port is smaller than the particle diameter of the corresponding gravel.

[0014] As a further optimization of the present invention, a backwashing head is movably connected inside the sand filter tank, and the bottom of both the sand filter tank and the regulating tank are fixedly connected with support legs. A drain pipe is fixedly connected to the bottom of the regulating tank, and a tank cover is movably connected to the top of both the sand filter tank and the regulating tank. The suspension pipe is fixedly connected to the tank cover, and the sewage pipe extends through the inside of the sand filter tank and is connected to the suspension pipe.

[0015] A method for pretreatment of landfill leachate includes the following steps: S1: Physical filtration, the landfill leachate is injected into the sand filter tank for filtration, and the sand and gravel inside the tank intercepts solid particles and suspended matter in the landfill leachate. S2: Backwashing. Regularly backwash the sand filter tank to prevent clogging of the sand filter and ensure the sand filtration effect. S3: pH adjustment. The filtered landfill leachate is introduced into the adjustment tank through a conduit for pH adjustment.

[0016] The beneficial effects of this invention are as follows: 1. The landfill leachate pretreatment equipment and method of the present invention reduces the impact of landfill leachate on gravel by diverting the leachate, preventing the gravel from being dispersed and affecting the filtration effect. When the landfill leachate passes through the diversion pipe, the water flow impact drives the spiral fan blades to rotate. The spiral fan blades apply rotational force to the diversion pipe, causing the diversion pipe to rotate using the bearings, which in turn drives the diversion pipe to rotate synchronously. This ensures that the diverted landfill leachate is evenly sprayed on the surface of the gravel, ensuring that the landfill leachate is evenly filtered by the gravel. This avoids the landfill leachate impacting only a local area of ​​the gravel, causing the gravel in that area to be clogged due to filtration load, reducing the backwashing frequency during filtration, and improving the filtration efficiency of landfill leachate.

[0017] 2. The landfill leachate pretreatment equipment and method of the present invention increases the space between the first sand trap and the second sand trap, so that the sand and gravel of different diameters inside the first sand trap and the second sand trap have enough space to roll during backwashing, thereby improving the backwashing effect of the sand and gravel. At the same time, the first sand trap and the second sand trap are used to intercept sand and gravel of different diameters, preventing different sand and gravel from mixing with each other, thereby ensuring that the filtration effect of the multi-layer sand and gravel is not affected.

[0018] 3. The landfill leachate pretreatment equipment and method of the present invention uses a deflector to drive the connecting seat, the pull rod and the extension rod to rotate synchronously, so that the stirring rod on the surface of the pull rod and the extension rod rotates synchronously. The stirring rod is used to stir the sand and gravel in the backwash, thereby improving the backwashing effect and efficiency of the sand and gravel, reducing the backwashing time, and further improving the filtration efficiency of landfill leachate.

[0019] 4. During backwashing, the wastewater inside the second and first sand traps can enter through the inlet on the surface of the stirring rod, and then be discharged through the drain chamber to the top of the pull rod and above the top sand, which speeds up the discharge of wastewater from the bottom sand, further reduces the backwashing time, and improves the filtration efficiency of landfill leachate. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic cross-sectional view of the sand filter tank of the present invention; Figure 3 This is a partial structural diagram of the spraying component of the present invention; Figure 4 This is a partial structural diagram of the backwash space expansion component of the present invention; Figure 5 This is a schematic diagram of the auxiliary sewage discharge component structure of the present invention; Figure 6 This is the present invention. Figure 2 Enlarged view of point A in the middle; Figure 7 This is a partial structural diagram of the backwashing auxiliary component of the present invention.

[0021] In the picture: 10. Sand filter tank; 11. Regulating tank; 12. Support legs; 13. Inlet pipe; 14. Guide pipe; 15. Backwash pipe; 16. Drain pipe; 17. Tank cover; 18. Backwash head; 19. Drain pipe; 20. Spraying assembly; 21. Suspension pipe; 22. Bearing; 23. Drainage pipe; 24. Spiral fan blade; 25. Diverter pipe; 26. Diverter hole; 30. Backwash space expansion assembly; 31. Piston plate; 32. Connecting frame; 33. Connecting seat; 34. Pull rod; 35. Extension rod; 36. First sand trap; 37. Second sand trap; 38. Limiting block; 39. Sensor; 40. Backwashing auxiliary component; 41. Directional pipe; 42. Clamping block; 43. Liquid inlet; 44. Baffle; 45. Spring-loaded hinge; 46. Stirring rod; 50. Auxiliary sewage discharge components; 51. Sewage inlet; 52. Sewage discharge chamber; 53. Sewage outlet. Detailed Implementation

[0022] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0023] like Figures 1 to 3 As shown in the figure, a landfill leachate pretreatment device according to an embodiment of the present invention includes a sand filter tank 10, an regulating tank 11, and a conduit 14 fixedly connecting the two. A water inlet pipe 13 and a sewage discharge pipe 16 are fixedly connected to both sides of the sand filter tank 10, and a backwash pipe 15 is fixedly connected to the bottom of the sand filter tank 10. A backwash head 18 is movably connected inside the sand filter tank 10. Support legs 12 are fixedly connected to the bottom of both the sand filter tank 10 and the regulating tank 11, and a drain pipe 19 is fixedly connected to the bottom of the regulating tank 11. A tank cover 17 is movably connected to the top of both the sand filter tank 10 and the regulating tank 11. A suspension pipe 21 is fixedly connected to the tank cover 17. The sewage discharge pipe 16 penetrates into the interior of the sand filter tank 10 and communicates with the suspension pipe 21. A uniform spraying component 20 is provided inside the sand filter tank 10 for uniformly spraying the landfill leachate onto the surface of the sand and gravel. The uniform spraying component 20 includes a suspension pipe 21 located at the top of the inside of the sand filter tank 10. The water inlet pipe 13 passes through the inside of the sand filter tank 10 and extends to connect with the suspension pipe 21. The bottom of the suspension pipe 21 is rotatably connected to a diversion pipe 23 via a bearing 22. A spiral fan blade 24 is fixedly connected inside the diversion pipe 23. A diversion pipe 25 is fixedly connected to the bottom of the diversion pipe 23, and a diversion hole 26 is opened on the surface of the diversion pipe 25.

[0024] It should be noted that, firstly, the landfill leachate is injected into the sand filter tank 10 through the inlet pipe 13. After entering the sand filter tank 10, the leachate flows through the suspension pipe 21 into the diversion pipe 23, and then through the diversion pipe 23 into the distribution pipe 25. Afterwards, it is dispersed and discharged through the diversion holes 26 on the surface of the distribution pipe 25, landing on the surface of the sand and gravel inside the sand filter tank 10. This diversion reduces the impact of the landfill leachate on the sand and gravel, preventing the sand and gravel from being dispersed and affecting the filtration effect. The leachate, as it passes through the diversion pipe 23, will… The spiral fan blade 24 is driven to rotate under the impact of water flow. The spiral fan blade 24 applies rotational force to the diversion pipe 23, causing the diversion pipe 23 to rotate using the bearing 22. This, in turn, drives the diversion pipe 25 to rotate synchronously, so that the diverted leachate is evenly sprayed on the surface of the gravel. This ensures that the leachate is evenly filtered by the gravel, preventing the leachate from only impacting a local area of ​​the gravel, which would cause the gravel to become clogged due to the filtration load in that area. This reduces the backwashing frequency during filtration and improves the filtration efficiency of the leachate. The filtered landfill leachate enters the regulating tank 11 through the conduit 14. The pH value of the landfill leachate is adjusted by adding chemicals, thereby completing the pretreatment of the landfill leachate. The pretreated landfill leachate is finally discharged through the drain pipe 19. If the sand becomes clogged during filtration, clean water is injected into the sand filter tank 10 through the backwash pipe 15. The clean water is diverted and pressurized through the backwash head 18 to backwash the sand. The impurities and dirt washed off are discharged to the outside of the sand filter tank 10 through the drain pipe 16.

[0025] like Figure 2 , Figure 4 and Figure 5 As shown, the sand filter tank 10 is provided with a backwash space expansion assembly 30 inside. The backwash space expansion assembly 30 includes a piston plate 31 movably connected to the inside of the sand filter tank 10. The bottom of the piston plate 31 is fixedly connected to a connecting seat 33 through a connecting frame 32. The bottom of the connecting seat 33 is fixedly connected to a pull rod 34. The bottom of the pull rod 34 is movably connected to an extension rod 35. The inside of the sand filter tank 10 is movably connected to a first sand trap 36. The upper end of the first sand trap 36 is movably connected to a second sand trap 37. There are two second sand traps 37. The pull rod 34 and the extension rod 35 pass through the two second sand traps 37 respectively and are fixedly connected to them. The extension rod 35 passes through the interior of the pull rod 34 and is fixedly connected to the limit block 38. The second sand trap 37 has an inverted "U" shaped structure that is wider at the top and narrower at the bottom. The two second sand traps 37 are stacked together with the first sand trap 36. The maximum distance that the extension rod 35 extends out of the pull rod 34 is less than the overlap height of the two second sand traps 37 and the first sand trap 36. A sensor 39 is fixedly connected to the outside of the suspension tube 21.

[0026] It should be noted that if the sand becomes clogged during the filtration process, the leachate entering the sand filter tank 10 cannot penetrate the sand. At this time, the leachate will quickly accumulate above the sand and push the piston plate 31 to rise. After the piston plate 31 rises, it triggers the sensor 39. It should be noted that the inlet pipe 13, the drain pipe 16, the conduit 14 and the backwash pipe 15 on the sand filter tank 10 are all equipped with solenoid valves. By triggering the sensor 39, the solenoid valves on the inlet pipe 13 and the conduit 14 are closed, and the solenoid valves on the backwash pipe 15 and the drain pipe 16 are opened. At this time, the backwash mode is started. During backwashing, as the piston plate 31 rises, the connecting bracket 32 ​​drives the connecting seat 33 to rise synchronously. After the connecting seat 33 rises, it drives the pull rod 34 and the extension rod 35 to rise. Since the pull rod 34 and the extension rod 35 pass through and are fixedly connected to the two second sand traps 37 respectively, the pull rod 34 and the extension rod 35 pull the two second sand traps 37 to rise during the rising process. Furthermore, since the maximum distance of the extension rod 35 extending outside the pull rod 34 is less than the overlap height of the two second sand traps 37 and the first sand trap 36, the space between the first sand trap 36 and the second sand trap 37 is increased while ensuring that the first sand trap 36 and the second sand trap 37 are not completely separated. This allows sand and gravel of different diameters inside the first sand trap 36 and the second sand trap 37 to have sufficient space to tumble during backwashing, improving the backwashing effect. At the same time, the first sand trap 36 and the second sand trap 37 intercept sand and gravel of different diameters, preventing them from mixing and ensuring that the filtration effect of the multi-layer sand and gravel is not affected. After the sand and gravel are cleaned by backwashing, the washed impurities and dirt are discharged through the drain pipe 16. At this time, the solenoid valves on the backwash pipe 15 and the drain pipe 16 are closed, and the solenoid valves on the water inlet pipe 13 and the guide pipe 14 are opened. The water accumulated above the sand and gravel smoothly penetrates the sand and gravel and enters the regulating tank 11 through the guide pipe 14, while the piston plate 31 moves downward and resets under the action of gravity.

[0027] like Figure 2 , Figure 6 and Figure 7 As shown, the sand filter tank 10 is provided with a backwashing auxiliary component 40 inside. The backwashing auxiliary component 40 includes a deflector tube 41 fixedly connected to the top of the connecting seat 33, and the surface of the deflector tube 41 is provided with a liquid inlet 43. The top of the deflector tube 41 is movably connected to a baffle 44 through a spring hinge 45. The pull rod 34 and the extension rod 35 are both fixedly connected to a stirring rod 46. A locking block 42 is fixedly connected to the surface of the deflector 41. The top of the deflector 41 extends into the interior of the drain pipe 23, and the inner wall of the drain pipe 23 is provided with a locking groove that matches the locking block 42.

[0028] It should be noted that after the piston plate 31 rises, it pushes the reversing pipe 41 into the interior of the drainage pipe 23 through the connecting seat 33, thereby blocking the diversion pipe 25 with the upper part of the reversing pipe 41. At the same time, the backwash wastewater enters the interior of the reversing pipe 41 through the liquid inlet 43 on its surface, and then enters the sewage pipe 16 through the drainage pipe 23 and is discharged outside the sand filter tank 10. It should be noted that the upper end of the reversing pipe 41 is movably connected to the baffle 44 through the spring hinge 45. Therefore, when the landfill leachate enters the interior of the drainage pipe 23, it impacts the top of the baffle 44, so that the baffle 44 always closes the reversing pipe 41. When backwashing, the flushing liquid enters the interior of the liquid inlet 43 and pushes the baffle 44 open from below, thereby ensuring that the flushing liquid can... The flushing fluid enters the drainage pipe 23 through the deflector pipe 41. When the flushing fluid enters the drainage pipe 23, it impacts the spiral fan blade 24, causing the spiral fan blade 24 to drive the drainage pipe 23 to rotate. When the deflector pipe 41 extends into the drainage pipe 23, the locking block 42 on its surface engages in the locking groove on the inner wall of the drainage pipe 23, thereby causing the drainage pipe 23 to drive the deflector pipe 41 to rotate synchronously. In turn, the deflector pipe 41 drives the connecting seat 33, the pull rod 34, and the extension rod 35 to rotate synchronously, causing the stirring rod 46 on the surface of the pull rod 34 and the extension rod 35 to rotate synchronously. The stirring rod 46 is used to stir the sand and gravel in the backwash, thereby improving the backwashing effect and efficiency of the sand and gravel, reducing the backwashing time, and further improving the filtration efficiency of landfill leachate.

[0029] like Figure 5 As shown, the sand filter tank 10 is provided with an auxiliary sewage discharge assembly 50 inside. The auxiliary sewage discharge assembly 50 includes a sewage inlet 51 opened on the surface of the stirring rod 46 on the extension rod 35. The stirring rod 46 is connected to the extension rod 35. The pull rod 34 is provided with a sewage discharge chamber 52 inside and a sewage discharge outlet 53 opened on the surface of the pull rod 34. The diameter of the inlet 51 on the surface of the stirring rod 46 decreases from top to bottom, and the diameter of the inlet 51 is smaller than the particle diameter of the corresponding gravel.

[0030] It should be noted that during backwashing, the wastewater inside the second sand trap 37 and the first sand trap 36 can enter their interiors through the inlet 51 on the surface of the stirring rod 46, and after reaching the top of the pull rod 34 through the discharge chamber 52, it is discharged through the discharge port 53 to the top of the uppermost sand and gravel, which speeds up the discharge of wastewater from the bottom sand and gravel, further reduces the backwashing time, and improves the filtration efficiency of landfill leachate.

[0031] A method for pretreatment of landfill leachate includes the following steps: S1: Physical filtration, the landfill leachate is injected into the sand filter tank 10 for filtration, and the sand and gravel inside the tank intercepts solid particles and suspended matter in the landfill leachate. S2: Backwashing. Regularly backwash the sand filter tank 10 to prevent clogging of the sand filter and ensure the sand filtration effect. S3: pH adjustment. The filtered landfill leachate is introduced into the adjustment tank 11 through the conduit 14 for pH adjustment.

[0032] The embodiments of the present invention have been described above, but the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the embodiments described above, all of which are within the protection scope of the embodiments described above.

Claims

1. A leachate pretreatment apparatus comprising a sand filter tank (10), a regulating tank (11) and a pipe (14) fixedly connecting the two, characterized in that: Both sides of the sand filter tank (10) are fixedly connected with a water inlet pipe (13) and a sewage pipe (16), and the bottom of the sand filter tank (10) is fixedly connected with a backwashing pipe (15), and the inside of the sand filter tank (10) is provided with a uniform spraying assembly (20) for uniformly spraying garbage leachate on the surface of sand. The uniform spraying assembly (20) comprises a hanging pipe (21) arranged at the top end of the inside of the sand filter tank (10), the water inlet pipe (13) penetrates the inside of the sand filter tank (10) and extends to be in communication with the hanging pipe (21), the bottom of the hanging pipe (21) is rotatably connected with a flow guide pipe (23) through a bearing (22), and the inside of the flow guide pipe (23) is fixedly connected with a spiral fan blade (24), the bottom of the flow guide pipe (23) is fixedly connected with a shunt pipe (25), and the surface of the shunt pipe (25) is provided with a shunt hole (26).

2. The apparatus for pretreatment of landfill leachate according to claim 1, characterized in that: The inside of the sand filter tank (10) is provided with a backwashing space expansion assembly (30), the backwashing space expansion assembly (30) comprises a piston plate (31) movably connected to the inside of the sand filter tank (10), and the bottom of the piston plate (31) is fixedly connected with a connecting seat (33) through a connecting frame (32), the bottom of the connecting seat (33) is fixedly connected with a pull rod (34), and the bottom of the pull rod (34) is movably connected with an extension rod (35), the inside of the sand filter tank (10) is movably connected with a first sand trap (36), and the upper end of the first sand trap (36) is movably connected with a second sand trap (37).

3. The apparatus for pretreatment of landfill leachate according to claim 2, characterized in that: The number of the second sand trap (37) is two, the pull rod (34) and the extension rod (35) respectively penetrate through the two second sand traps (37) and are fixedly connected therewith, and the extension rod (35) penetrates into the inside of the pull rod (34) and is fixedly connected with a limiting block (38).

4. The apparatus according to claim 3, characterized in that: The second sand trap (37) is an inverted "convex" structure with wide upper end and narrow lower end, the two second sand traps (37) and the first sand trap (36) are stacked together, the maximum distance of the extension rod (35) extending out of the pull rod (34) is less than the overlapping height of the two second sand traps (37) and the first sand trap (36), and the outside of the hanging pipe (21) is fixedly connected with a sensor (39).

5. A device for the pretreatment of landfill leachate according to claim 4, characterized in that: The inside of the sand filter tank (10) is provided with a backwashing auxiliary assembly (40), the backwashing auxiliary assembly (40) comprises a change direction pipe (41) fixedly connected to the top of the connecting seat (33), and the surface of the change direction pipe (41) is provided with a liquid inlet (43), the top of the change direction pipe (41) is movably connected with a baffle (44) through a rebound hinge (45), and the outside of the pull rod (34) and the extension rod (35) is fixedly connected with a stirring rod (46).

6. The apparatus for pretreatment of landfill leachate according to claim 5, characterized in that: The surface of the change direction pipe (41) is fixedly connected with a clamping block (42), and the top of the change direction pipe (41) penetrates into the inside of the flow guide pipe (23), and the inner wall of the flow guide pipe (23) is provided with a clamping groove matched with the clamping block (42).

7. A device for the pretreatment of landfill leachate according to claim 6, characterized in that: The sand filter tank (10) is internally provided with an auxiliary pollution discharge assembly (50), the auxiliary pollution discharge assembly (50) comprises a pollution inlet (51) arranged on the surface of the stirring rod (46) of the extension rod (35), the stirring rod (46) is communicated with the extension rod (35), the pull rod (34) is internally provided with a pollution discharge cavity (52), and the pull rod (34) is provided with a pollution discharge opening (53) on the surface.

8. A device for the pre-treatment of landfill leachate according to claim 7, characterized in that: The diameter of the pollution inlet (51) arranged on the surface of the stirring rod (46) decreases from top to bottom, and the diameter of the pollution inlet (51) is smaller than the particle diameter of the corresponding sand.

9. A device for the pre-treatment of landfill leachate according to claim 8, characterized in that: The sand filter tank (10) is internally movably connected with a backwashing head (18), the bottom of the sand filter tank (10) and the bottom of the adjusting tank (11) are fixedly connected with supporting legs (12), the bottom of the adjusting tank (11) is fixedly connected with a drain pipe (19), the top of the sand filter tank (10) and the top of the adjusting tank (11) are movably connected with tank covers (17), the suspension pipe (21) is fixedly connected with the tank cover (17), and the pollution discharge pipe (16) penetrates into the sand filter tank (10) and is in communication connection with the suspension pipe (21).

10. A method for the pre-treatment of landfill leachate, which is suitable for use in a treatment plant according to any one of claims 1 to 9, characterised in that: The method comprises the following steps: S1: physical filtration, the landfill leachate is injected into the sand filter tank (10) for filtration, and the sand in the tank body is used to intercept solid particles and suspended solids in the landfill leachate; S2: backwashing, the sand filter tank (10) is backwashed regularly to avoid clogging of sand filtration and ensure the sand filtration effect; S3: PH adjustment, the filtered landfill leachate is introduced into the adjusting tank (11) through the conduit (14) for PH adjustment.

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