Landfill leachate treatment device and working method thereof

Abstract

The invention relates to a landfill leachate treatment device and a working method thereof, the device comprises a primary settling tank, a secondary settling tank and a tertiary settling tank, the lower parts of the primary settling tank and the secondary settling tank are communicated through a communicating pipe, and the secondary settling tank and the tertiary settling tank are communicated through an overflow pipe; sludge valves are mounted at the bottoms of the primary settling tank, the secondary settling tank and the tertiary settling tank, the sludge valves are communicated with a sludge conveying pipe, the three sludge valves are simultaneously communicated with the sludge conveying pipe, and a spiral feeding device is mounted in the sludge conveying pipe; a flocculant box is mounted at the top of the primary settling box, a rotating joint is connected to the lower end of the flocculant box, a stirring shaft is connected to the lower end of the rotating joint, and a flocculant channel is formed in the stirring shaft; the secondary settling tank is divided into three layers, the lowermost layer and the second layer of the secondary settling tank are communicated through an electromagnetic valve, the second layer and the third layer of the secondary settling tank are communicated through an electromagnetic valve, and the tertiary settling tank is divided into two layers.

Description

Technical Field

[0001] The invention relates to the field of landfill leachate treatment, in particular to a landfill leachate treatment device and a working method thereof. Background Art

[0002] In theory, garbage composting is an excellent way to recycle garbage, which can simultaneously achieve garbage reduction, harmlessness and resource utilization. However, in reality, there are many problems in the production and promotion of garbage composting, and the cost of composting production is relatively high. Compared with composting and landfilling, incineration technology has better garbage reduction, resource utilization and harmlessness effects. The amount of garbage residue after incineration is small, and the heat generated by incineration can be used for power generation. Whether incineration or sanitary landfilling is used, a certain amount of high-concentration organic wastewater leachate will be generated during the garbage disposal process. The generation of high-concentration leachate in landfills mainly comes from the following aspects: (1) atmospheric precipitation and surface runoff; (2) moisture contained in the garbage itself; (3) moisture generated by microbial metabolic activities during the garbage landfill process. Among them, atmospheric precipitation is the main source of leachate. Rainwater that exceeds the water holding capacity of the garbage and its covering soil layer and the surface evaporation potential enters the landfill site and flows through the garbage layer, thereby generating high-concentration organic wastewater. During the flow process, leachate is affected by multiple factors, including physical factors, chemical factors, and biological factors, so its characteristic pollutants vary widely. Generally, the pH value of leachate is between 4 and 9, the COD concentration can fluctuate between 2000 and 65000 mg / L, and the BOD5 concentration is between 200 and 45000 mg / L. In addition to extremely high concentrations of pollutants such as COD, BOD5, and NH3-N, the leachate wastewater also contains halogenated aromatic hydrocarbons, heavy metals, and pathogenic pollutants. It is a high-concentration organic wastewater with complex components, high toxicity, and extremely difficult treatment. If it is not properly treated and directly discharged into the environment, it will cause serious pollution to surface water, groundwater, soil, and human living environment, and pose a serious threat to the health of the surrounding people.

[0003] In the prior art, a patent with announcement number CN101597131A discloses a method and device for treating landfill leachate, wherein the method comprises the steps of pretreatment, anaerobic treatment, membrane biochemical treatment, nanofiltration treatment and sludge treatment; the treatment device comprises a primary sedimentation tank and a regulating tank, wherein the regulating tank is connected to an anaerobic reactor, which is connected to a denitrification tank, which is connected to a nitrification tank; the nitrification tank is connected to an ultrafiltration device, which is connected to a nanofiltration device.

[0004] The key and difficulty of leachate treatment is the removal of COD and ammonia nitrogen. There are many types of existing processes and equipment for leachate treatment, but there are generally problems such as lengthy treatment processes, multiple equipment, difficult actual operation and management, and low integration of treatment links, which leads to high energy consumption in leachate treatment, unstable treatment effect and low treatment efficiency.

[0005] In view of the above problems, in the prior art, the patent with announcement number CN112591988B discloses a garbage leachate treatment device and a garbage leachate treatment method, including a denitrification-nitrification treatment tank and an oxidation treatment tank; the denitrification-nitrification treatment tank is connected to the oxidation treatment tank, and a valve A is provided at the connection point, the valve A includes a first door body and a second door body, there is a gap between the first door body and the second door body, the top of the first door body and the second door body are detachably connected to the same connecting plate, the connecting plate is connected to a driving mechanism A for driving it to rise and fall, a tubular membrane filter plate is provided in the gap, and the tubular membrane filter plate is slidably connected to the connection point between the denitrification-nitrification treatment tank and the oxidation treatment tank. In the scheme, the valve structure between two adjacent treatment tanks is improved, and the corresponding tubular membrane filter plate and resin adsorption plate are inserted before opening the valve. The structure is simple and easy to operate. Preliminary filtration and deep purification are carried out during the flow of leachate, and the efficiency is significantly improved.

[0006] The above technical solution adopts a stepped layout, connecting the denitrification-nitrification treatment tank and the oxidation treatment tank; the denitrification-nitrification treatment tank is connected with the oxidation treatment tank, thereby realizing the treatment of the leachate, and it installs filter plates and resin plates at the connected parts to realize filtration and cleaning, but it only realizes the treatment of the back end of the leachate treatment, and the leachate still contains a large amount of impurities, such as solid impurities and oil impurities. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defect of incomplete filtering and cleaning in the prior art and to provide a garbage leachate treatment device and a working method thereof.

[0008] The technical solution adopted by the present invention to solve the technical problem is a garbage leachate treatment device and a working method thereof, comprising a primary sedimentation tank, a secondary sedimentation tank and a tertiary sedimentation tank, wherein the lower parts of the primary sedimentation tank and the secondary sedimentation tank are connected by a connecting pipe, and the secondary sedimentation tank and the tertiary sedimentation tank are connected by an overflow pipe, and the bottoms of the primary sedimentation tank, the secondary sedimentation tank and the tertiary sedimentation tank are all equipped with sludge valves, the sludge valves are connected to the sludge conveying pipe, and the three sludge valves are connected to the sludge conveying pipe at the same time, and a spiral feeding device is installed in the sludge conveying pipe; A flocculant tank is installed on the top of the primary sedimentation tank, and a rotary joint is connected to the lower end of the flocculant tank, and a stirring shaft is connected to the lower end of the rotary joint, and a flocculant channel is provided in the stirring shaft; the secondary sedimentation tank is divided into three layers, and the bottom layer and the second layer, and the second layer and the third layer of the secondary sedimentation tank are connected through solenoid valves, and a plurality of primary filter barrels are installed in the bottom layer of the secondary sedimentation tank; the tertiary sedimentation tank is divided into two layers, a tertiary buffer net is provided in the first layer of the tertiary sedimentation tank, and an atmospheric pipe is provided on the right side of the first layer, a connecting pipe is provided between the first layer and the second layer of the tertiary sedimentation tank, a booster pump is installed on the connecting pipe, an ultrafiltration pipe is installed in the second layer of the tertiary sedimentation tank, and a discharge pipe is installed on the right side of the second layer.

[0009] Furthermore, a worm gear is installed on the stirring shaft, a power motor is installed on the top of the primary sedimentation tank, a worm is installed on the output end of the power motor, and the worm and the worm gear are meshed with each other.

[0010] Furthermore, a leachate pipe is connected to the side of the primary sedimentation tank, an inlet pump is installed on the leachate pipe, a buffer baffle is installed on the water inlet side of the primary sedimentation tank, a water outlet baffle is installed on the water outlet side of the primary sedimentation tank, and a buffer net is connected between the water outlet baffle and the buffer baffle.

[0011] Furthermore, a pressure storage chamber is installed in the second layer of the second sedimentation tank, a rubber plate is fixed to the left end of the pressure storage chamber, a transverse piston is slidably installed in the pressure storage chamber, the upper and lower walls of the pressure storage chamber have water holes, a buffer tank is installed on the side of the bottom layer, a downward pressure piston is slidably installed in the buffer tank, a counterweight is installed on the downward pressure piston, an aeration pipe is installed under the third layer of the second sedimentation tank, a partition is installed in the third layer of the secondary sedimentation tank, a water permeable hole is opened on the partition, an exhaust pipe is installed on the upper side of the third layer of the secondary sedimentation tank, and an overflow pipe connected to the tertiary sedimentation tank is installed on the right side of the third layer.

[0012] The technical solution adopted by the present invention to further solve the technical problem is a working method using a garbage leachate treatment device, comprising the following steps: S1. The primary sedimentation tank works: the inlet pump on the leachate pipe works and adds leachate, and the leachate enters the primary sedimentation tank. The start and stop of the inlet pump is controlled by judging the pressure in the primary sedimentation tank. When the pressure reaches the high threshold, the inlet pump stops working, and the flocculant is added through the flocculant tank and the flocculant channel. At the same time, the power motor works to drive the worm to rotate, the worm rotation drives the worm wheel rotation, and the worm wheel rotation drives the stirring shaft to rotate for stirring, so that the flocculant is fully mixed with the leachate; S2, sedimentation in the primary sedimentation tank: after a delay of more than 20 minutes, the power motor stops working, and the flocculated leachate is then precipitated in the primary sedimentation tank; S3, secondary sedimentation tank operation: the supernatant after being treated in the primary sedimentation tank enters the bottom of the secondary sedimentation tank through the connecting pipe, and enters the right side of the primary filter barrel after being initially filtered through the primary filter barrel, while generating pressure and squeezing the downward pressure piston on the buffer tank to rise; S4, secondary sedimentation tank reaction: after a delay of more than 30 minutes, the solenoid valve between the first and second layers opens, and under the action of the downward piston and the counterweight, the water temporarily stored in the buffer tank enters the second layer through the solenoid valve. At the same time, the water pressure in the second layer increases, and the piston in the pressure storage chamber is squeezed outward, and then the solenoid valve between the first and second layers is closed; S5, secondary sedimentation tank sedimentation: after the reaction is completed, the solenoid valve between the second and third layers is opened, and then the transverse piston moves to the right under the action of the air pressure on its left side, so that the water in the second layer sump enters the third layer through the solenoid valve, and then the solenoid valve between the second and third layers is closed, and the third layer is aerated through the aeration pipe, and then an oxidation reaction is carried out in the third layer to further treat the sewage. After the treatment is completed, the sewage overflows and enters the third layer sedimentation tank; S6, the operation of the tertiary sedimentation tank: after the overflow sewage is buffered and precipitated, the water is pumped to the second layer by the booster pump. Under the pressure of the booster pump, the water is filtered through the ultrafiltration tube and enters the inner side of the ultrafiltration tube and then enters the space on the right side of the ultrafiltration tube. After the ultrafiltration tube filters the macromolecules, the purified water is discharged from the discharge pipe; S7. Sludge discharge: After purification is completed, the mud valve opens and the spiral feeding device works to send the sludge out. The sludge is treated by drying or incineration.

[0013] In summary, the present invention has the following beneficial technical effects: The invention solves the problem of processing solid impurities and oil pollution in the leachate, has a high degree of integration, and can realize large-scale processing of the leachate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the overall structure of an embodiment of a garbage leachate treatment device and a working method thereof of the present invention.

[0015] Description of reference numerals: 1. Primary sedimentation tank; 11. Connecting pipe; 12. Flocculant tank; 13. Rotary joint; 14. Stirring shaft; 141. Flocculant channel; 15. Worm gear; 16. Worm; 17. Leachate pipe; 18. Liquid inlet pump; 19. Primary buffer net; 191. Buffer baffle; 192. Water outlet baffle; 20. Power motor; 2. Secondary sedimentation tank; 21. Primary filter barrel; 22. Pressure storage chamber; 221. Transverse piston; 222. Water collection trough; 223, water distribution trough; 23, rubber sheet; 24, buffer tank; 241, downward piston; 242, counterweight; 25, aeration pipe; 26, partition; 261, water permeable hole; 27, exhaust pipe; 28, overflow pipe; 29, solenoid valve; 3, tertiary sedimentation tank; 31, tertiary buffer net; 32, atmospheric pipe; 33, booster pump; 34, ultrafiltration pipe; 35, discharge pipe; 36, connecting pipe; 4, sludge valve; 5, sludge conveying pipe. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0017] Reference Figure 1 This embodiment includes a primary sedimentation tank 1, a secondary sedimentation tank 2 and a tertiary sedimentation tank 3. The lower parts of the primary sedimentation tank 1 and the secondary sedimentation tank 2 are connected by a connecting pipe 11, and the secondary sedimentation tank 2 and the tertiary sedimentation tank 3 are connected by an overflow pipe 28. The bottoms of the primary sedimentation tank 1, the secondary sedimentation tank 2 and the tertiary sedimentation tank 3 are all equipped with sludge valves 4, and the sludge valves 4 are connected to the sludge conveying pipe 5, and the three sludge valves 4 are connected to the sludge conveying pipe 5 at the same time, and a spiral feeding device is installed in the sludge conveying pipe 5.

[0018] A flocculant box 12 is installed on the upper outer side of the primary sedimentation tank 1, and a rotary joint 13 is connected to the lower end of the flocculant box 12. A stirring shaft 14 is connected to the lower end of the rotary joint 13. A flocculant channel 141 is provided in the stirring shaft 14, and a worm gear 15 is installed on the stirring shaft 14. A power motor 20 is installed on the primary sedimentation tank 1, and a worm 16 coaxially rotates on the output end of the power motor 20. The worm 16 and the worm gear 15 are meshed with each other. A leachate pipe 17 is connected to the left side of the primary sedimentation tank 1, and an inlet pump 18 is installed on the leachate pipe 17. A buffer baffle 191 is installed on the water inlet side of the primary sedimentation tank 1, and a water outlet baffle 192 is installed on the water outlet side of the primary sedimentation tank 1, and a primary buffer net 19 is connected between the water outlet baffle 192 and the buffer baffle 191.

[0019] The secondary sedimentation tank 2 is divided into three layers, which are the first layer, the second layer, and the third layer from small to top. The first layer and the second layer, and the second layer and the third layer of the secondary sedimentation tank 2 are connected through a solenoid valve 29. The first layer of the secondary sedimentation tank 2 is equipped with multiple primary filter barrels 21, and a pressure storage chamber 22 is installed in the second layer of the second sedimentation tank. A rubber plate 23 is fixed to the left end of the pressure storage chamber 22. A transverse piston 221 is slidably installed in the pressure storage chamber 22. The upper and lower walls of the pressure storage chamber 22 have water holes. A buffer tank 24 is installed on the side of the first layer, and a downward pressure piston 241 is slidably installed in the buffer tank 24. A counterweight 242 is installed on the downward pressure piston 241. An aeration pipe 25 is installed below the third layer of the second sedimentation tank 2, and two layers of partitions 26 are installed in the third layer. Water permeable holes 261 are opened on the partitions 26. An exhaust pipe 27 is installed on the upper side of the third layer, and an overflow pipe 28 connected to the tertiary sedimentation tank 3 is installed on the right side.

[0020] In addition, the gap between the pressure storage chamber 22 and the second and third layer partitions is a water collecting tank 222, and the gap between the pressure storage chamber 22 and the first and second layer partitions is a water distribution tank 223.

[0021] The tertiary sedimentation tank 3 is divided into two layers. A tertiary buffer net 31 is arranged in the first layer of the tertiary sedimentation tank 3. At the same time, an atmospheric pipe 32 is arranged on the right side of the first layer. A connecting pipe 36 is connected between the first layer and the second layer. A booster pump 33 is installed on the connecting pipe 36. An ultrafiltration tube 34 is installed in the second layer of the tertiary sedimentation tank 3, and a discharge pipe 35 is installed on the right side of the second layer.

[0022] A working method using the above-mentioned garbage leachate treatment device comprises the following steps: S1. The primary sedimentation tank 1 works: the liquid inlet pump 18 on the leachate pipe 17 works and adds leachate, and the leachate enters the primary sedimentation tank 1. The start and stop of the liquid inlet pump 18 is controlled by judging the pressure in the primary sedimentation tank 1. When the pressure reaches a high threshold, the liquid inlet pump 18 stops working, and the flocculant is added through the flocculant tank 12 and the flocculant channel 141. At the same time, the power motor 20 works to drive the worm 16 to rotate, and the rotation of the worm 16 drives the worm wheel 15 to rotate, and the rotation of the worm wheel 15 drives the stirring shaft 14 to rotate for stirring, so that the flocculant is fully mixed with the leachate; in this embodiment, the flocculant can be selected from polysilicic acid flocculants; S2, sedimentation in the primary sedimentation tank 1: after a delay of more than 20 minutes, 30 minutes in this embodiment, the power motor 20 stops working, and the flocculated leachate is precipitated in the primary sedimentation tank 1; S3, the secondary sedimentation tank 2 works: the supernatant after being processed by the primary sedimentation tank 1 enters the bottom of the secondary sedimentation tank 2 through the connecting pipe 11, and enters the right side of the primary filter screen barrel 21 after being initially filtered by the primary filter screen barrel 21, and at the same time, pressure is generated and the downward pressure piston 241 on the buffer tank 24 is pressed upward; S4, reaction of the secondary sedimentation tank 2: after a delay of more than 30 minutes, which is 1 hour in this embodiment, the solenoid valve 29 between the first and second layers is opened, and under the action of the downward piston 241 and the counterweight 242, the water temporarily stored in the buffer tank 24 enters the water distribution tank 223 in the second layer through the solenoid valve 29, and at the same time, the water pressure in the second layer increases, thereby squeezing the piston in the pressure storage chamber 22 outward, and then the solenoid valve 29 between the first and second layers is closed; wherein, the pressure storage chamber 22 is filled with granular microbial attachment materials, and then denitrification and nitrification reactions are carried out in the second layer of the secondary sedimentation tank 2, thereby achieving denitrification treatment of the leachate; S5, sedimentation in the secondary sedimentation tank 2: After the reaction is completed, the solenoid valve 29 between the second and third layers of the secondary sedimentation tank 2 is opened, and then the transverse piston 221 moves to the right under the air pressure on its left side, so that the water in the second-layer water collection tank 222 enters the third layer through the solenoid valve 29, and then the solenoid valve 29 between the second and third layers is closed, and the third layer is aerated through the aeration pipe 25, and then an oxidation reaction is carried out in the third layer to further treat the sewage. After the treatment is completed, the sewage (leachate) overflows and enters the third-layer sedimentation tank; S6, the tertiary sedimentation tank 3 works: after the overflow sewage is buffered and precipitated, the water is pumped to the second layer of the tertiary sedimentation tank 3 by the booster pump 33. Under the pressure of the booster pump 33, the water is filtered through the ultrafiltration tube 34 and enters the inner side of the ultrafiltration tube 34 and then enters the right side space of the ultrafiltration tube 34. After the ultrafiltration tube 34 filters the macromolecules, the purified water is discharged from the discharge pipe 35. S7. Sludge discharge: After purification is completed, the mud valve opens and the spiral feeding device works to send the sludge out. The sludge is treated by drying or incineration.

[0023] The above are all preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby. Among them, the same parts are represented by the same figure numerals. It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings, and the words "inside" and "outside" refer to the directions toward or away from the geometric center of a specific component, respectively. Therefore: All equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A landfill leachate treatment device, It is characterized in that The invention comprises a primary sedimentation tank (1), a secondary sedimentation tank (2) and a tertiary sedimentation tank (3); the lower parts of the primary sedimentation tank (1) and the secondary sedimentation tank (2) are connected by a connecting pipe (11); the secondary sedimentation tank (2) and the tertiary sedimentation tank (3) are connected by an overflow pipe (28); sludge valves (4) are installed at the bottom of the primary sedimentation tank (1), the secondary sedimentation tank (2) and the tertiary sedimentation tank (3); the sludge valves (4) are connected to a sludge conveying pipe (5); and the three sludge valves (4) are connected to the sludge conveying pipe (5) at the same time; and a spiral feeding device is installed in the sludge conveying pipe (5); The top of the primary sedimentation tank (1) is provided with a flocculant tank (12), the lower end of the flocculant tank (12) is connected to a rotary joint (13), the lower end of the rotary joint (13) is connected to a stirring shaft (14), and the stirring shaft (14) has a flocculant channel (141); the secondary sedimentation tank (2) is divided into three layers, the lowermost layer and the second layer of the secondary sedimentation tank (2) and the second layer and the third layer are connected via a solenoid valve (29), and the lowermost layer of the secondary sedimentation tank (2) is provided with a rotary joint (13), the lower end of the rotary joint (13) is connected to a stirring shaft (14), and the stirring shaft (14) has a flocculant channel (141); A plurality of primary filter screen barrels (21) are installed; the tertiary sedimentation tank (3) is divided into two layers, a tertiary buffer screen (31) is arranged in the first layer of the tertiary sedimentation tank (3), and an atmospheric pipe (32) is arranged on the right side of the first layer; a connecting pipe (36) is provided between the first layer and the second layer of the tertiary sedimentation tank (3), and a booster pump (33) is installed on the connecting pipe (36); an ultrafiltration tube (34) is installed in the second layer of the tertiary sedimentation tank (3), and a discharge pipe (35) is installed on the right side of the second layer.

2. A landfill leachate treatment device according to claim 1, It is characterized in that A worm gear (15) is mounted on the stirring shaft (14), a power motor (20) is mounted on the top of the primary sedimentation tank (1), a worm (16) is mounted on the output end of the power motor (20), and the worm (16) and the worm gear (15) are meshed with each other.

3. A landfill leachate treatment device according to claim 1, It is characterized in that A leachate pipe (17) is connected to the side of the primary sedimentation tank (1), a liquid inlet pump (18) is installed on the leachate pipe (17), a buffer baffle (191) is installed on the water inlet side of the primary sedimentation tank (1), a water outlet baffle (192) is installed on the water outlet side of the primary sedimentation tank (1), and a primary buffer net (19) is connected between the water outlet baffle (192) and the buffer baffle (191).

4. A landfill leachate treatment device according to claim 1, It is characterized in that A pressure storage chamber (22) is installed in the second layer of the secondary sedimentation tank, a rubber plate (23) is fixed at the left end of the pressure storage chamber (22), a transverse piston (221) is slidably installed in the pressure storage chamber (22), the upper and lower walls of the pressure storage chamber (22) have water holes, a buffer tank (24) is installed on the side of the lowest layer, a downward pressure piston (241) is slidably installed in the buffer tank (24), and a counterweight (242) is installed on the downward pressure piston (241), an aeration pipe (25) is installed below the third layer of the secondary sedimentation tank (2), a partition (26) is installed in the third layer of the secondary sedimentation tank (2), and a water permeable hole (261) is opened on the partition (26), an exhaust pipe (27) is installed on the upper side of the third layer of the secondary sedimentation tank (2), and an overflow pipe (28) connected to the tertiary sedimentation tank (3) is installed on the right side of the third layer.

5. A method for using the garbage leachate treatment device according to any one of claims 1 to 4, It is characterized in that The following steps are involved: S1, the primary sedimentation tank (1) works: the liquid inlet pump (18) on the leachate pipe (17) works and adds leachate, and the leachate enters the primary sedimentation tank (1). The start and stop of the liquid inlet pump (18) is controlled by judging the pressure in the primary sedimentation tank (1). When the pressure reaches a high threshold, the liquid inlet pump (18) stops working, and flocculants are added through the flocculant tank (12) and the flocculant channel (141). At the same time, the power motor (20) works to drive the worm (16) to rotate, and the rotation of the worm (16) drives the worm wheel (15) to rotate, and the rotation of the worm wheel (15) drives the stirring shaft (14) to rotate for stirring, so that the flocculant is fully mixed with the leachate; S2, sedimentation in the primary sedimentation tank (1): after a delay of more than 20 minutes, the power motor (20) stops working, and the flocculated leachate is then precipitated in the primary sedimentation tank (1); S3, the secondary sedimentation tank (2) works: the supernatant after being processed in the primary sedimentation tank (1) enters the bottom of the secondary sedimentation tank (2) through the connecting pipe (11), enters the right side of the primary filter barrel (21) after being initially filtered by the primary filter barrel (21), and at the same time generates pressure and presses the downward pressure piston (241) on the buffer tank (24) to rise; S4, reaction of the secondary sedimentation tank (2): after a delay of more than 30 minutes, the electromagnetic valve (29) between the first layer and the second layer is opened, and under the action of the downward piston (241) and the counterweight (242), the water temporarily stored in the buffer tank (24) enters the second layer through the electromagnetic valve (29), and at the same time, the water pressure in the second layer increases, thereby squeezing the piston in the pressure storage chamber (22) outward, and then the electromagnetic valve (29) between the first layer and the second layer is closed; S5, secondary sedimentation tank (2) sedimentation: after the reaction is completed, the electromagnetic valve (29) between the second layer and the third layer is opened, and then the transverse piston (221) moves to the right under the action of the air pressure on its left side, so that the water in the second layer water collection tank enters the third layer through the electromagnetic valve (29), and then the electromagnetic valve (29) between the second layer and the third layer is closed, and the third layer is aerated through the aeration pipe (25), and then an oxidation reaction is carried out in the third layer to further treat the sewage. After the treatment is completed, the sewage overflows and enters the third layer sedimentation tank; S6, the tertiary sedimentation tank (3) works: after the overflowing sewage is buffered and precipitated, the water is pumped to the second layer by the booster pump (33). Under the pressure of the booster pump (33), the water is filtered through the ultrafiltration tube (34) and enters the inner side of the ultrafiltration tube (34) and then enters the right side space of the ultrafiltration tube (34). After the ultrafiltration tube (34) filters the macromolecules, the purified water is discharged from the discharge pipe (35); S7. Sludge discharge: After purification is completed, the mud valve opens and the spiral feeding device works to send the sludge out. The sludge is treated by drying or incineration.

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