Low-maintenance efficient pretreatment pool

Abstract

The invention discloses a low-maintenance high-efficiency pretreatment tank, and relates to the technical field of sewage treatment equipment, the low-maintenance high-efficiency pretreatment tank comprises a first cavity, a second cavity and a third cavity; a first fixed barrel is fixedly arranged at the upper part in the first cavity, and a first water inlet is formed in the lower end of the first fixed barrel; a first cylindrical filter screen is arranged in the first fixed barrel, a first annular cavity is formed between the inner side wall of the first fixed barrel and the outer side wall of the first cylindrical filter screen, and an opening in the lower end of the first annular cavity is closed; the first annular cavity is communicated with the second cavity; a communication channel used for being communicated with the third cavity is formed in the second cavity, at least one inclined baffle is fixedly arranged in the communication channel, the inclined baffle is provided with a first end and a second end which are opposite, in the vertical direction, the second end is lower than the first end, and the first end is fixedly connected with the inner wall of the communication channel; the third cavity is provided with a discharge port which is higher than the inner bottom of the third cavity. The processing efficiency can be improved, the maintenance frequency is reduced, and the labor intensity of operation and maintenance personnel is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment equipment, and particularly to a low-maintenance and high-efficiency pretreatment tank. Background Art

[0002] A large amount of pollutants are contained in rural domestic sewage, and the sewage needs to be treated before discharge to prevent environmental and water body pollution.

[0003] Generally, a basket-type grille is used for the grille unit of small-scale sewage treatment. The grille aperture is 10-20 mm with a large aperture, and the interception effect of the grille is poor. A large amount of debris and suspended particulate matter enter the regulation tank, resulting in frequent cleaning of the regulation tank. At the same time, it affects the subsequent biochemical treatment system. When the grille aperture is 5-10 mm with a small aperture, the interception efficiency of suspended particulate matter is improved, but it requires regular cleaning by maintenance personnel, resulting in an increased operation and maintenance frequency and an increased labor intensity of maintenance personnel. Summary of the Invention

[0004] The purpose of the present invention is to provide a low-maintenance and high-efficiency pretreatment tank to solve the problems existing in the above-mentioned prior art, improve the treatment efficiency, reduce the maintenance frequency, and reduce the labor intensity of maintenance personnel.

[0005] To achieve the above purpose, the present invention provides the following solution:

[0006] The present invention provides a low-maintenance and high-efficiency pretreatment tank, including a first cavity, a second cavity, and a third cavity; the first cavity is used to receive the sewage to be treated; a first fixed barrel is fixedly arranged above the first cavity, and a first water inlet communicating with the first cavity is arranged at the lower end of the first fixed barrel; a first cylindrical filter screen is arranged inside the first fixed barrel, and a first annular cavity is formed between the inner side wall of the first fixed barrel and the outer side wall of the first cylindrical filter screen. The lower end opening of the first annular cavity is closed, and the inside of the first cylindrical filter screen communicates with the first water inlet; the first annular cavity communicates with the second cavity; a communication channel for communicating with the third cavity is arranged in the second cavity, and at least one inclined baffle is fixedly arranged in the communication channel. The inclined baffle has opposite first and second ends. In the vertical direction, the second end is lower than the first end, and the first end is fixedly connected to the inner wall of the communication channel; the third cavity has a discharge port, and the discharge port is higher than the inner bottom of the third cavity.

[0007] Preferably, a second fixed barrel is fixedly arranged above the third cavity, and a second water inlet connected to the third cavity is arranged at the lower end of the second fixed barrel; a second cylindrical filter screen is arranged in the second fixed barrel, and a second annular cavity is formed between the inner wall of the second fixed barrel and the outer wall of the second cylindrical filter screen, the lower end opening of the second annular cavity is closed, and the interior of the second cylindrical filter screen is connected to the second water inlet; the second annular cavity is connected to the discharge port; the aperture diameter of the filter holes of the second cylindrical filter screen is smaller than the aperture diameter of the filter holes of the first cylindrical filter screen.

[0008] Preferably, the connecting channel has a first inner side wall and a second inner side wall; the first inner side wall is opposite to the second inner side wall; a plurality of the inclined baffles are fixedly provided on the first inner side wall, and a plurality of the inclined baffles are fixedly provided on the second inner side wall; in the vertical direction, the inclined baffles on the first inner side wall and the inclined baffles on the second inner side wall are arranged alternately in sequence; and in the vertical direction, each of the inclined baffles on the first inner side wall has an overlapping area with the adjacent inclined baffles on the second inner side wall.

[0009] Preferably, a mud flushing pipe is fixedly arranged in the second cavity; flushing water is supplied in the mud flushing pipe, and the mud flushing pipe is provided with a plurality of punching holes for flushing mud at the bottom of the second cavity.

[0010] Preferably, in the vertical direction, the upper end of the first cylindrical filter screen is lower than the inner top of the first fixed barrel; the inner cavity of the first fixed barrel above the upper end of the first cylindrical filter screen forms a connecting cavity; the upper end opening of the first annular cavity is connected to the connecting cavity, and the upper end opening of the first cylindrical filter screen is connected to the connecting cavity; in the vertical direction, the height of the connecting cavity is higher than the highest point inside the first cavity.

[0011] Preferably, a receiving ring plate is fixedly provided at the lower end opening of the first fixed barrel, and the inner hole of the receiving ring plate forms the first water inlet; a shelf ring plate is fixed to the lower end of the first cylindrical filter screen, and the outer diameter of the shelf ring plate is larger than the inner diameter of the inner hole of the receiving ring plate, and the outer diameter of the shelf ring plate is not larger than the inner diameter of the first fixed barrel.

[0012] Preferably, a first closing cover is detachably fixed and closed at the upper opening of the first fixed barrel; and at least one lifting ear is fixed to the upper end of the first cylindrical filter screen.

[0013] Preferably, the first cavity, the second cavity and the third cavity are all part of the inner cavity of an outer cylinder; the inner cavity of the outer cylinder is sequentially divided into the first cavity, the second cavity and the third cavity by two partition plates.

[0014] Preferably, a first manhole and a second manhole are provided on the outer cylinder, the first manhole communicates with the inner cavity of the second cavity, and the second manhole communicates with the inner cavity of the communication channel.

[0015] Preferably, an overflow pipe is fixed on the first fixed barrel, one end of the overflow pipe communicates with the first annular cavity, and the other end of the overflow pipe communicates with the second cavity.

[0016] The present invention has achieved the following technical effects compared with the prior art:

[0017] The low-maintenance and high-efficiency pretreatment tank provided by the present invention is provided with three filtering cavities, namely a first cavity, a second cavity and a third cavity; after the sewage enters the first cavity, after preliminary precipitation, it enters the first annular cavity through the first water inlet of the first fixed barrel and the filtration of the first cylindrical filter screen. The first cylindrical filter screen can intercept impurities and sediment in the first cavity, and part of the sediment is precipitated at the inner bottom of the first cavity; the filtered water entering the second cavity is intercepted by the baffle in the communication channel, so that the sediment in the filtered water is further intercepted and precipitated at the inner bottom of the second cavity; the filtered water entering the third cavity can be fully precipitated again before being discharged because the discharge port is located at a high place; by adopting multi-stage filtration and precipitation, the sewage can be fully purified, and the treatment efficiency is improved; in addition, the setting of the first annular cavity can also play a buffering role, enabling the water flow to enter the second cavity smoothly, avoiding the impact of the water flow on the subsequent cavities, and being beneficial to the stable progress of the precipitation process. At the same time, the design of the inclined baffle in the communication channel changes the water flow path, reduces the flow rate and forms a turbulent flow, increasing the chance of separation of impurities and water in the sewage, thereby improving the precipitation efficiency and further enhancing the overall treatment efficiency; the inclined baffle enables the precipitated impurities to slide along the inclined baffle to the lower position at the bottom of the channel, facilitating centralized cleaning; through the cooperation of multi-stage filtration and precipitation, while effectively intercepting the sewage, it can greatly reduce the impact of the intercepted substances on the subsequent regulation tank and biochemical treatment system, especially the biological filter process, which can greatly extend the cleaning cycle of the filter media in the biological filter process, greatly improve the treatment effect of the filter media, reduce the maintenance frequency, and reduce the labor intensity of the operation and maintenance personnel. Description of the Drawings

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of the overall structure of a low-maintenance and high-efficiency pretreatment pool provided by the present invention;

[0020] Figure 2 A top view of the low-maintenance, high-efficiency pretreatment tank provided by the present invention.

[0021] In the figure:

[0022] 10-first cavity; 11-water inlet pipe; 12-first fixed barrel; 13-first cylindrical filter screen; 14-first annular cavity; 15-connecting cavity; 16-receiving ring plate; 17-resting ring plate; 18-hanging ear; 19-flow pipe;

[0023] 20-second cavity; 21-connecting channel; 22-inclined baffle; 23-mud flushing pipe; 24-first manhole; 25-second manhole;

[0024] 30-third cavity; 31-second fixed barrel; 32-water outlet pipe;

[0025] 40-Divider plate. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The purpose of the present invention is to provide a low-maintenance and high-efficiency pretreatment pool to solve the problems existing in the prior art, improve the treatment efficiency, reduce the maintenance frequency, and reduce the labor intensity of operation and maintenance personnel.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Embodiment 1

[0030] This embodiment provides a low-maintenance and high-efficiency pretreatment tank, such as Figure 1 and Figure 2As shown, it includes a first cavity 10, a second cavity 20 and a third cavity 30; the first cavity 10 is used for receiving sewage to be treated; a first fixed barrel 12 is fixedly arranged above the first cavity 10, and a first water inlet communicating with the first cavity 10 is arranged at the lower end of the first fixed barrel 12; a first cylindrical filter screen 13 is arranged in the first fixed barrel 12, and a first annular cavity 14 is formed between the inner side wall of the first fixed barrel 12 and the outer side wall of the first cylindrical filter screen 13. The lower end opening of the first annular cavity 14 is closed, and the inside of the first cylindrical filter screen 13 communicates with the first water inlet; the first annular cavity 14 communicates with the second cavity 20; a communication channel 21 for communicating with the third cavity 30 is arranged in the second cavity 20 (a square hole is arranged on the partition plate 40 between the second cavity 20 and the third cavity 30, and the square hole communicates the communication channel 21 with the third cavity 30), and at least one inclined baffle 22 is fixedly arranged in the communication channel 21. The inclined baffle 22 has opposite first and second ends. In the vertical direction, the second end is lower than the first end, and the first end is fixedly connected to the inner wall of the communication channel 21; the third cavity 30 has a discharge port, and the discharge port is higher than the inner bottom of the third cavity 30.

[0031] By setting three filtering cavities of the first cavity 10, the second cavity 20 and the third cavity 30; after the sewage enters the first cavity 10 and undergoes preliminary sedimentation (the particulate matters with larger specific gravity in the sewage first undergo preliminary sedimentation by themselves), it enters the first annular cavity 14 through the first water inlet of the first fixed barrel 12 and is filtered by the first cylindrical filter screen 13. The first cylindrical filter screen 13 can intercept impurities and sediment in the first cavity 10, and part of the sediment is deposited at the inner bottom of the first cavity 10; the filtered water entering the second cavity 20 is intercepted by the folded flow of the inclined baffle 22 in the communication channel 21, so that the sediment and the like in the filtered water are further intercepted and deposited at the inner bottom of the second cavity 20; for the filtered water entering the third cavity 30, since the discharge port is located at a high position, it can be fully sedimented again before being discharged; by adopting multi-stage filtering and sedimentation, the sewage can be fully purified and the treatment efficiency can be improved; moreover, the setting of the first annular cavity 14 can also play a buffering role, enabling the water flow to enter the second cavity 20 smoothly, avoiding the impact of the water flow on the subsequent cavities, and being beneficial to the stable progress of the sedimentation process. At the same time, the design of the inclined baffle 22 in the communication channel 21 changes the water flow path, reduces the flow rate and forms a turbulent flow, increasing the opportunity for the separation of impurities and water in the sewage, thereby improving the sedimentation efficiency and further enhancing the overall treatment efficiency; the inclined baffle 22 enables the deposited impurities to slide along the inclined baffle 22 to the lower position at the bottom of the channel, facilitating centralized cleaning; through the cooperation of multi-stage filtering and sedimentation, while effectively intercepting the sewage, it can greatly reduce the impact of the intercepted substances on the subsequent regulating tank and biochemical treatment system, especially for the biological filter process, which can greatly extend the cleaning cycle of the filter media in the biological filter process, greatly improve the treatment effect of the filter media, reduce the maintenance frequency, and reduce the labor intensity of the maintenance personnel.

[0032] Specifically, both the first cylindrical filter screen 13 and the second annular filter screen are cylindrical grilles. The difference between the cylindrical grille and the traditional basket grille is that the cylindrical grille intercepts impurities and sediment in the first cavity 10 or the third cavity 30, while the traditional basket grille intercepts impurities in the basket grille, thus greatly extending the cleaning cycle.

[0033] Among them, regarding the formation settings of the first cavity 10, the second cavity 20, and the third cavity 30:

[0034] In an alternative solution of this embodiment, preferably, as Figure 1 and Figure 2 shown, the first cavity 10, the second cavity 20, and the third cavity 30 are all part of the inner cavity of an outer cylinder; the inner cavity of the outer cylinder is sequentially divided into the first cavity 10, the second cavity 20, and the third cavity 30 by two partition plates 40. The overall structure is based on an outer cylinder and different cavities are divided by the partition plates 40. Compared with a combination of multiple independent tanks, it occupies less area and has a high space utilization rate, and can integrate the pretreatment function within a limited site, especially suitable for places with limited space.

[0035] Among them, regarding the relevant settings in the first cavity 10:

[0036] Specifically, a water inlet pipe 11 communicating with its inner cavity is provided on the first cavity 10.

[0037] Specifically, the first cylindrical filter screen 13 can intercept suspended solid impurities below 10 millimeters.

[0038] In an alternative solution of this embodiment, preferably, as Figure 1 shown, in the vertical direction, the upper end of the first cylindrical filter screen 13 is lower than the inner top of the first fixed barrel 12; a communicating cavity 15 is formed in the inner cavity of the first fixed barrel 12 above the upper end of the first cylindrical filter screen 13; the upper end opening of the first annular cavity 14 communicates with the communicating cavity 15, and the upper end opening of the first cylindrical filter screen 13 also communicates with the communicating cavity 15; in the vertical direction, the height of the communicating cavity 15 is higher than the highest point inside the first cavity 10.

[0039] Specifically, the setting of the communicating cavity 15 enables sewage to enter the first annular cavity 14 in an overflow manner when the first cylindrical filter screen 13 is blocked and not cleaned in time, and finally enter the second cavity 20, without affecting the sewage treatment, and the inclined baffles 22 in the second cavity 20 can also intercept the sundries and garbage originally intercepted by the first cylindrical filter screen 13.

[0040] Specifically, the first fixed barrel 12 is fixed to the outer cylinder.

[0041] In an alternative embodiment of the present embodiment, preferably, as Figure 1 shown, a receiving ring plate 16 is fixedly arranged at the lower opening of the first fixed barrel 12, and the inner hole of the receiving ring plate 16 forms a first water inlet; a placing ring plate 17 is fixed at the lower end of the first cylindrical filter net 13, the outer diameter of the placing ring plate 17 is larger than the inner diameter of the inner hole of the receiving ring plate 16, and the outer diameter of the placing ring plate 17 is not larger than the inner diameter of the first fixed barrel 12.

[0042] Specifically, the receiving ring plate 16 is fixed to the inner bottom of the first fixed barrel 12, there is a distance between the receiving ring plate 16 and the bottom of the first fixed barrel 12, the receiving ring plate 16 and the first fixed barrel 12 are integrally formed, and a plurality of reinforcing ribs are further arranged on one side of the receiving ring plate 16 close to the bottom of the first fixed barrel 12. Each reinforcing rib is circumferentially and uniformly distributed around the axis of the first fixed barrel 12, and the reinforcing ribs are used to fixedly connect the receiving ring plate 16 and the inner side wall of the first fixed barrel 12 together.

[0043] Specifically, the first cylindrical filter net 13 is directly placed in the first fixed barrel 12 without being fixed; the first cylindrical filter net 13 is made of stainless steel; the cooperation between the placing ring plate 17 and the receiving ring plate 16 can realize the radial limit of the first cylindrical filter net 13 (for example, the inner diameter of the first fixed barrel 12 is set to 700 mm, and the outer diameter of the placing ring plate 17 is set to 695 mm).

[0044] In an alternative embodiment of the present embodiment, preferably, as Figure 1 shown, a first closing cover is detachably and fixedly closed at the upper opening of the first fixed barrel 12; at least one lifting lug 18 is fixed at the upper end of the first cylindrical filter net 13.

[0045] Specifically, the setting of the lifting lug 18 facilitates taking out the first cylindrical filter net 13 from the first fixed barrel 12.

[0046] In an alternative embodiment of the present embodiment, preferably, as Figure 1 shown, an overflow pipe 19 is fixed on the first fixed barrel 12, one end of the overflow pipe 19 is communicated with the first annular cavity 14, and the other end of the overflow pipe 19 is communicated with the second cavity 20.

[0047] Among them, the relevant settings in the second cavity 20 are described as follows:

[0048] In an alternative embodiment of the present embodiment, preferably, as Figure 1 and Figure 2 shown, a first manhole 24 and a second manhole 25 are arranged on the outer cylinder body. The first manhole 24 is communicated with the inner cavity of the second cavity 20, and the second manhole 25 is communicated with the inner cavity of the communication channel 21.

[0049] In an alternative embodiment of the present embodiment, preferably, asFigure 1 As shown, the inside of the communication channel 21 has a first inner wall and a second inner wall; the first inner wall and the second inner wall are opposite to each other; a plurality of inclined baffles 22 are fixedly arranged on the first inner wall, and a plurality of inclined baffles 22 are fixedly arranged on the second inner wall; in the vertical direction, the inclined baffles 22 on the first inner wall and the inclined baffles 22 on the second inner wall are arranged in a staggered manner in sequence; and in the vertical direction, each inclined baffle 22 on the first inner wall and the adjacent inclined baffle 22 on the second inner wall have an overlapping area.

[0050] Specifically, the water in the second cavity 20 undergoes several upward folding flows, and the sewage realizes the interception and precipitation of sediment and light impurities.

[0051] In an alternative embodiment of the present embodiment, preferably, as Figure 1 and Figure 2 shown, a sludge flushing pipe 23 is fixedly arranged in the second cavity 20; flushing water is supplied in the sludge flushing pipe 23, and a plurality of punching holes for facing the sludge at the bottom of the second cavity 20 are arranged on the sludge flushing pipe 23.

[0052] Specifically, two rows of punching holes are arranged at the bottom of the sludge flushing pipe 23, each row has a plurality of punching holes, the bottom of the sludge flushing pipe 23 is a horizontal cross pipe, and one row of punching holes is arranged on each side of the vertical plane passing through the axis of the horizontal cross pipe; the central axis of the punching hole forms an angle of 45° with the vertical plane.

[0053] Specifically, the sludge flushing pipe 23 is externally connected to a water pump, and the water pump supplies flushing water, and the flushing pipe is used for periodically impacting the sludge at the bottom of the second cavity 20 to prevent the sludge from caking.

[0054] Specifically, the sludge flushing pipe 23 extends to the inner bottom position of the second cavity 20 corresponding to the opening below the communication channel 21, and it can impact the accumulated sludge at the opening below the communication channel 21 to prevent the sludge at this position from being too high.

[0055] Specifically, 99% of the sediment in the original sewage can be intercepted by passing through each inclined baffle 22. At the same time, it can effectively block the small - particle - size light suspended matter that is not intercepted by the first cylindrical filter net 13 from entering the third cavity 30, avoiding affecting the subsequent biochemical system, and solving the problems of frequent cleaning and large operation and maintenance workload caused by small - aperture grilles. It only needs to be cleaned regularly (generally 6 - 12 months), which is far less frequent than the conventional grille cleaning (generally once a week).

[0056] Specifically, through the functions of the first cylindrical filter screen 13 and each inclined baffle 22, the interception efficiency is greatly improved, and at the same time, the cleaning frequency of the pretreatment tank is reduced accordingly, effectively reducing the maintenance and management work of the pretreatment tank in the process; and the sludge flushing pipe 23 arranged in the second cavity 20 can use a water pump to cooperate with the sludge flushing pipe 23 to impact the sludge at the bottom regularly, preventing caking and facilitating the problem of incomplete sludge discharge during cleaning.

[0057] Among them, the relevant settings in the third cavity 30 are described as follows:

[0058] In an alternative embodiment of the present embodiment, preferably, as Figure 1 and Figure 2 shown, a second fixed barrel 31 is fixedly arranged above the third cavity 30. A second water inlet communicating with the third cavity 30 is arranged at the lower end of the second fixed barrel 31; a second cylindrical filter screen is arranged in the second fixed barrel 31. A second annular cavity is formed between the inner side wall of the second fixed barrel 31 and the outer side wall of the second cylindrical filter screen. The lower end opening of the second annular cavity is closed, and the inside of the second cylindrical filter screen communicates with the second water inlet; the second annular cavity communicates with the discharge port; the aperture of the filter holes of the second cylindrical filter screen is smaller than the aperture of the filter holes of the first cylindrical filter screen 13.

[0059] Specifically, in the structure of the second fixed barrel 31 and the second cylindrical filter screen in the third cavity 30, except that the aperture of the filter holes of the second cylindrical filter screen is smaller than the aperture of the filter holes of the first cylindrical filter screen 13, the others are the same as the structure of the first fixed barrel 12 and the first cylindrical filter screen 13 in the first cavity 10, and will not be elaborated here; the second annular cavity is discharged from the third cavity 30 through a water outlet pipe 32, and the end of the water outlet pipe 32 forms a discharge port.

[0060] Among them, the relevant settings are described as follows:

[0061] Specifically, a corresponding closing cover is arranged at each of the first manhole 24, the second manhole 25 and the upper opening of the second fixed barrel 31.

[0062] Specifically, the first cylindrical filter screen 13 can block large-particle sundries and part of the sediment in the first cavity 10. Then, after passing through multiple inclined baffles 22, the water flows in a zigzag manner and rises for sedimentation. 99% of the sediment and light impurities are blocked in the second cavity 20. This structure can extend the period of sundries cleaning and reduce the maintenance frequency. At the same time, the design of the inclined baffles 22 can resist the impact of the rainwater entering from the water inlet pipe 11; in the one-month test, the low-maintenance and high-efficiency pretreatment tank of this embodiment can treat three times the designed water volume (the designed scale is 30 tons / day, that is, 90 tons / day), and can also achieve the precipitation of 99% of the impurities and sediment. When each inclined baffle 22 was tested, the designed residence time was 4 to 5 hours, and when the water volume increased to three times, the actual residence time was 1 to 1.5 hours (the flow velocity at the inclined baffle 22 was less than 20 mm / s). Thus, the cost of the pretreatment tank is reduced as a whole, and the function of the pretreatment tank is improved.

[0063] In the present invention, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A low-maintenance and highly efficient pretreatment tank, characterized in that: It includes a first cavity, a second cavity and a third cavity; The first cavity is used to receive the sewage to be treated; a first fixed barrel is fixedly arranged above the first cavity, and a first water inlet communicating with the first cavity is arranged at the lower end of the first fixed barrel; a first cylindrical filter screen is arranged in the first fixed barrel, and a first annular cavity is formed between the inner side wall of the first fixed barrel and the outer side wall of the first cylindrical filter screen. The lower end opening of the first annular cavity is closed, and the inside of the first cylindrical filter screen communicates with the first water inlet; the first annular cavity communicates with the second cavity; A communication channel for communicating with the third cavity is arranged in the second cavity, and at least one inclined baffle is fixedly arranged in the communication channel. The inclined baffle has opposite first and second ends. In the vertical direction, the second end is lower than the first end, and the first end is fixedly connected to the inner wall of the communication channel; The third cavity has a discharge port, and the discharge port is higher than the inner bottom of the third cavity.

2. The low-maintenance and highly efficient pretreatment tank according to claim 1, wherein: A second fixed barrel is fixedly arranged above the third cavity, and a second water inlet communicating with the third cavity is arranged at the lower end of the second fixed barrel; a second cylindrical filter screen is arranged in the second fixed barrel, and a second annular cavity is formed between the inner side wall of the second fixed barrel and the outer side wall of the second cylindrical filter screen. The lower end opening of the second annular cavity is closed, and the inside of the second cylindrical filter screen communicates with the second water inlet; the second annular cavity communicates with the discharge port; The aperture of the filter holes of the second cylindrical filter screen is smaller than the aperture of the filter holes of the first cylindrical filter screen.

3. The low-maintenance and highly efficient pretreatment tank according to claim 1, characterized in that: The inside of the communication channel has a first inner side wall and a second inner side wall; the first inner side wall and the second inner side wall are opposite to each other; A plurality of the inclined baffles are fixedly arranged on the first inner side wall, and a plurality of the inclined baffles are fixedly arranged on the second inner side wall; in the vertical direction, the inclined baffles on the first inner side wall and the inclined baffles on the second inner side wall are arranged alternately in sequence; and in the vertical direction, each of the inclined baffles on the first inner side wall and the adjacent inclined baffles on the second inner side wall has an overlapping area.

4. The low-maintenance and highly efficient pretreatment tank according to claim 1, characterized in that: A sludge flushing pipe is fixedly arranged in the second cavity; flushing water is supplied in the sludge flushing pipe, and a plurality of punching holes for facing the sludge at the inner bottom of the second cavity are arranged on the sludge flushing pipe.

5. The low-maintenance and highly efficient pre-treatment tank according to claim 1, characterized in that: In the vertical direction, the upper end of the first cylindrical filter screen is lower than the inner top of the first fixed barrel; a communication cavity is formed in the inner cavity of the first fixed barrel above the upper end of the first cylindrical filter screen; The upper end opening of the first annular cavity communicates with the communication cavity, and the upper end opening of the first cylindrical filter screen communicates with the communication cavity; In the vertical direction, the height of the communication cavity is higher than the highest point inside the first cavity.

6. The low-maintenance and highly efficient pretreatment tank according to claim 1, characterized in that: A receiving ring plate is fixedly arranged at the lower end opening of the first fixed barrel, and the inner hole of the receiving ring plate forms the first water inlet; A suspension ring plate is fixed to the lower end of the first cylindrical filter net, the outer diameter of the suspension ring plate is greater than the inner diameter of the inner hole of the receiving ring plate, and the outer diameter of the suspension ring plate is not greater than the inner diameter of the first fixed barrel.

7. The low-maintenance and highly efficient pre-treatment tank according to claim 6, characterized in that: A first closing cover is detachably fixed and closed at the upper end opening of the first fixed barrel; At least one lifting lug is fixed to the upper end of the first cylindrical filter net.

8. The low-maintenance and highly efficient pretreatment tank according to claim 1, wherein: The first cavity, the second cavity and the third cavity are all parts of the inner cavity of an outer cylinder; The inner cavity of the outer cylinder is sequentially divided into the first cavity, the second cavity and the third cavity by two partition plates.

9. The low-maintenance and highly efficient pretreatment tank according to claim 8, characterized in that: A first manhole and a second manhole are provided on the outer cylinder, the first manhole communicates with the inner cavity of the second cavity, and the second manhole communicates with the inner cavity of the communication channel.

10. The low-maintenance and highly efficient pretreatment tank according to claim 1, characterized in that: An overflow pipe is fixed to the first fixed barrel, one end of the overflow pipe communicates with the first annular cavity, and the other end of the overflow pipe communicates with the second cavity.

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