CN114432745B - A multi-stage treatment device for sewage plants - Google Patents

Abstract

The invention discloses a multistage treatment device for a sewage plant, relates to the field of sewage treatment, solves the problem of poor sedimentation effect of a sedimentation tank of the sewage plant in the prior art, and has the technical key points that: comprising the following steps: the sedimentation tank comprises a first sedimentation tank and a second sedimentation tank, and the first sedimentation tank and the second sedimentation tank alternately sediment sewage; the switching pipe is connected with the sewage pump, is arranged at one end of the sedimentation tank and can rotate around the axis of the switching pipe; the sedimentation tank switching unit is fixedly connected to one end of the sedimentation tank, which is provided with a switching pipe, and is connected with the switching pipe; according to the invention, the sedimentation tank switching unit controls the switching pipe to alternately discharge sewage into the first sedimentation tank and the second sedimentation tank, so that the first sedimentation tank and the second sedimentation tank can sediment when not discharging sewage, and the sedimentation effect is improved.

Description

A multi-stage treatment device for sewage plants

Technical field

The present invention relates to the field of sewage treatment, and in particular to a multi-stage treatment device for sewage plants.

Background technique

Sewage treatment refers to the process of purifying sewage so that it meets the water quality requirements for discharge into a certain water body or reuse. Sewage treatment is widely used in various fields such as construction, agriculture, transportation, energy, petrochemicals, environmental protection, urban landscape, medical care, catering, etc., and is increasingly entering the daily lives of ordinary people. According to the classification of sewage sources, sewage treatment is generally divided into production sewage treatment and domestic sewage treatment. Production sewage includes wastewater generated during the production process of industrial enterprises, while domestic sewage is the sewage generated in daily life, which refers to a complex mixture of various forms of inorganic and organic matter.

In the process of sewage treatment, sedimentation is an essential step. The sedimentation process is used to treat solid impurities in sewage. However, in the existing technology, the sedimentation tank continuously inputs sewage. After the sewage is filled into the sedimentation tank, it is easy to accumulate at the bottom of the sedimentation tank. The sludge is splashed, thus affecting the sedimentation effect. Therefore, we propose a multi-stage treatment device for sewage plants.

Contents of the invention

The technical problem to be solved by the present invention is to provide a multi-stage treatment device for a sewage treatment plant to solve the problem of poor sedimentation effect of the sedimentation tank in the sewage treatment plant in the prior art.

In order to achieve the above objects, the present invention provides the following technical solutions:

A multi-stage treatment device for sewage plants, including:

A sedimentation tank, the sedimentation tank is used to sediment sewage, the sedimentation tank includes a first sedimentation tank and a second sedimentation tank, the first sedimentation tank and the second sedimentation tank alternately sediment sewage;

Switching pipe, the switching pipe is connected to the sewage pump, the switching pipe is used to pour sewage into the first sedimentation tank and the second sedimentation tank, the switching pipe is installed at one end of the sedimentation tank, and the switching pipe can rotate around its own axis;

The sedimentation tank switching unit is used to control the switching pipe to pour sewage into the first sedimentation tank and the second sedimentation tank respectively. The sedimentation tank switching unit is fixedly connected to one end of the sedimentation tank where the switching pipe is provided, and the sedimentation tank The switching unit is connected to the switching pipe.

As a further solution of the present invention, one end of the switching pipe is provided with a right-angle elbow, the sedimentation tank is provided with a support column, the support column is provided with a semicircular sinking tank, and the switching pipe is installed to the support column through an upper cover. The upper cover is an arc-shaped plate, and the upper cover is fixedly connected to the support column.

As a further solution of the present invention, one end of the switching tube away from the right-angled elbow is also connected to a connector. The connector includes a connecting sleeve and a water inlet pipe. The connecting sleeve is cylindrical with openings at both ends. The switching pipe is away from the right-angled elbow. One end of the elbow is provided with a second limit ring, and the second limit ring is located in the connecting sleeve. One end of the connecting sleeve close to the switching pipe is provided with an inner blocking ring. The second limiting ring is clamped on the connecting sleeve through the inner blocking ring. Inside, the water inlet pipe is fixed into the connecting sleeve through threaded fit, and the water inlet pipe presses the second limiting ring against the inner blocking ring.

As a further solution of the present invention, an end bearing is provided between the water inlet pipe and the second limiting ring.

As a further solution of the present invention, the sedimentation tank switching unit includes a switching switch and a switching tube driving unit. There are two sets of switching switches, and the switching switches are respectively connected to one end of the first sedimentation tank and the second sedimentation tank, so The switching switch controls the switching tube driving unit to operate when the sewage in the first sedimentation tank or the second sedimentation tank reaches a preset water level, and the switching tube driving unit controls the rotation of the switching tube.

As a further solution of the present invention, the switch includes a communication tube, a trigger tube and a return spring. The communication tube is a cylinder with an opening at one end. The communication tube is fixedly connected to the first sedimentation tank and the second sedimentation tank. The pipe is provided with an overflow hole and a first outlet hole on both the first sedimentation tank and the second sedimentation tank. The overflow hole is located at a first water level on the first sedimentation tank and the second sedimentation tank. The first water level is The water level when the sedimentation tank is filled, the first outlet hole is located at the second water level on the first sedimentation tank and the second sedimentation tank, and the second water level is the water level when the sewage in the first sedimentation tank and the second sedimentation tank is emptied. water level; the trigger tube is provided with a water storage tank, the water storage tank is arranged along the axis of the trigger pipe, the bottom of the water storage tank is provided with a second water outlet hole, the second water outlet hole is located on the side of the trigger pipe, and the second water outlet hole It is connected with the water tank, and the trigger pipe is set inside the communicating pipe; the return spring is set at the bottom of the communicating pipe, and the bottom of the communicating pipe is provided with a contact switch. The contact switch is a delay switch, and the contact switch is connected to the switching pipe. Drive unit and power supply.

As a further solution of the present invention, the bottom of the communication pipe is also provided with a pressure relief hole.

As a further solution of the present invention, the switching tube driving unit includes a driving motor, the driving motor is connected to the switching switch on the first settling tank and the second settling tank respectively, and the switching switches on the first settling tank and the second settling tank are respectively controlled. The drive motor rotates forward and reverse, a worm is fixedly connected to the output shaft of the drive motor, a worm gear is fixedly connected to the switching tube, and the worm meshes with the worm gear.

As a further solution of the present invention, the multi-stage treatment device for sewage plants also includes an alarm unit. The alarm unit includes a first alarm module, a second alarm module and a third alarm module. The first alarm module The trigger switch is set in the switch switch connected to the first sedimentation tank; the trigger switch of the second alarm module is set in the switch switch connected to the second sedimentation tank; the third alarm module is provided with two sets of trigger switches connected in series , and the two sets of trigger switches connected to the third alarm module are respectively located in the switches connected to the first sedimentation tank and the second sedimentation tank.

To sum up, compared with the prior art, the present invention has the following beneficial effects:

1. The present invention controls the switching pipe to alternately discharge sewage into the first sedimentation tank and the second sedimentation tank through the sedimentation tank switching unit, so that the first sedimentation tank and the second sedimentation tank can settle when the sewage is not discharged, thereby improving the sedimentation effect. .

2. The present invention can automatically control the switching pipe to alternately discharge sewage into the first sedimentation tank and the second sedimentation tank, saving manpower and improving the automation level of the sedimentation tank.

3. The present invention is equipped with an alarm unit, which can remind the staff when the sewage in the first sedimentation tank and the second sedimentation tank is full, so that the sewage conditions in the first sedimentation tank and the second sedimentation tank can be easily observed.

Description of the drawings

Figure 1 is a schematic structural diagram of a multi-stage treatment device used in a sewage plant.

Figure 2 is a schematic structural diagram of a sedimentation tank switching unit in a multi-stage treatment device used in a sewage plant.

Figure 3 is an exploded view of a multi-stage treatment device used in a sewage plant.

Figure 4 is a schematic structural diagram of a left side view of a multi-stage treatment device used in a sewage plant.

FIG. 5 is a cross-sectional view along M-M in FIG. 4 .

Figure 6 is a schematic structural diagram of a sedimentation tank in a multi-stage treatment device used in a sewage plant from a first perspective.

Figure 7 is a schematic structural diagram of a sedimentation tank in a multi-stage treatment device used in a sewage plant from a second perspective.

Figure 8 is a schematic structural diagram of a switching pipe used in a multi-stage treatment device in a sewage plant.

Reference signs: 100-first sedimentation tank, 110-installation plate, 120-support column, 130-upper cover, 200-second sedimentation tank, 300-switch, 310-connecting pipe, 311-overflow hole, 312 -The first water outlet, 320-trigger pipe, 321-reservoir, 322-second water outlet, 313-pressure relief hole, 330-return spring, 400-switching pipe, 410-right angle elbow, 420-first limit Position ring, 430-second limit ring, 500-switching tube drive unit, 510-drive motor, 520-worm, 530-worm gear, 540-shaft seat, 600-connector, 610-connection sleeve, 620-end bearing , 630-water inlet pipe, 700-dust shell.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on The embodiments of the present invention and all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

As shown in Figures 1 to 5, a multi-stage treatment device for sewage plants is used for sedimentation of sewage, including:

A sedimentation tank, the sedimentation tank is used to sediment sewage, the sedimentation tank includes a first sedimentation tank 100 and a second sedimentation tank 200, the first sedimentation tank 100 and the second sedimentation tank 200 alternately sediment sewage;

Switching pipe 400, the switching pipe 400 is connected to the sewage pump, the switching pipe 400 is used to pour sewage into the first sedimentation tank 100 and the second sedimentation tank 200, the switching pipe 400 is installed at one end of the sedimentation tank, and the switching pipe 400 is able to rotate around its own axis;

The sedimentation tank switching unit is used to control the switching pipe 400 to pour sewage into the first sedimentation tank 100 and the second sedimentation tank 200 respectively. The sedimentation tank switching unit is fixedly connected to the sedimentation tank where the switching pipe 400 is provided. One end, and the sedimentation tank switching unit is connected to the switching pipe 400;

As shown in Figures 6 and 7, the first sedimentation tank 100 and the second sedimentation tank 200 are formed by building partitions into a trough-shaped sedimentation tank, so that the first sedimentation tank 100 and the second sedimentation tank 200 are arranged adjacent to each other. At the same time, the switching pipe 400 only needs to rotate a preset angle to pour sewage into the first sedimentation tank 100 and the second sedimentation tank 200 respectively. When the first sedimentation tank 100 is filled with sewage, the sewage in the second sedimentation tank 200 begins to flow. Before the first sedimentation tank 100 is filled, the sewage pump in the second sedimentation tank 200 empties the sewage in the second sedimentation tank 200. After the sewage in the first sedimentation tank 100 is filled, the sedimentation tank switching unit controls the switching pipe. 400 rotation, thereby pouring sewage into the second sedimentation tank 200, and the sewage in the first sedimentation tank 100 begins to settle. The first sedimentation tank 100 and the second sedimentation tank 200 alternately settle the sewage, which can improve the sedimentation effect of the sewage;

As shown in Figure 8, one end of the switching tube 400 is provided with a right-angle elbow 410. When the switching tube 400 rotates, the right-angle elbow 410 switches from the first sedimentation tank 100 to the second sedimentation tank 200 or from the second sedimentation tank 200 to the second sedimentation tank 200. The sedimentation tank 200 is switched to the first sedimentation tank 100, so that the sewage can alternately flow into the first sedimentation tank 100 and the second sedimentation tank 200. The sedimentation tank is provided with a support column 120, and the support column 120 is provided with a semicircular The switching tube 400 is installed on the support column 120 through the upper cover 130. The upper cover 130 is an arc-shaped plate. The upper cover 130 is fixedly connected to the support column 120, so that the switching tube 400 can only rotate around itself. The axis rotates. In some examples, the upper cover 130 is fixedly connected to the support column 120 through bolts;

Preferably, in order to prevent the switching tube 400 from moving on the support column 120, the switching tube 400 is also provided with a first limiting ring 420. The first limiting ring 420 is sleeved on the supporting column 120 away from the right-angle elbow 410. On one side, the first limiting ring 420 is fixedly connected to the switching tube 400. In some examples, the first limiting ring 420 is fixedly connected to the switching tube 400 by welding;

As a preferred mode of the present invention, the end of the switching pipe 400 away from the right-angle elbow 410 is also connected to a connector 600. The connector 600 is used to prevent the sewage pipe from rotating when the switching pipe 400 rotates. The connector 600 600 includes a connecting sleeve 610 and a water inlet pipe 630. The connecting sleeve 610 is cylindrical with openings at both ends. The switching pipe 400 is provided with a second limiting ring 430 at one end away from the right-angle elbow 410. The second limiting ring 430 is located at In the connecting sleeve 610, one end of the connecting sleeve 610 close to the switching pipe 400 is provided with an inner blocking ring. The second limiting ring 430 is clamped in the connecting sleeve 610 through the inner blocking ring. The water inlet pipe 630 is fixed to the connecting sleeve through threaded fit. 610, and the water inlet pipe 630 presses the second limiting ring 430 against the inner blocking ring, thereby preventing leakage of sewage between the connecting sleeve 610 and the second limiting ring 430;

Preferably, an oil seal is provided between the switching pipe 400 and the connecting sleeve 610 to prevent sewage from leaking from between the switching pipe 400 and the connecting head 600;

Furthermore, in order to reduce the friction between the water inlet pipe 630 and the second limiting ring 430 when the switching pipe 400 rotates, an end bearing 620 is provided between the water inlet pipe 630 and the second limiting ring 430; when switching When the pipe 400 rotates, the second limiting ring 430 drives the bearing end close to the second limiting ring 430 to rotate, and the bearing end close to the water inlet pipe 630 does not rotate;

The sedimentation tank switching unit includes a switching switch 300 and a switching tube driving unit 500. There are two sets of switching switches 300, and the switching switches 300 are respectively connected to one end of the first sedimentation tank 100 and the second sedimentation tank 200. The switch 300 controls the switching tube driving unit 500 to work when the sewage in the first sedimentation tank 100 or the second sedimentation tank 200 reaches the preset water level, and the switching tube driving unit 500 controls the rotation of the switching tube 400;

The switch 300 includes a communication tube 310, a trigger tube 320 and a return spring 330. The communication tube 310 is cylindrical with an opening at one end. The communication tube 310 is fixedly connected to the first sedimentation tank 100 and the second sedimentation tank 200. , the communication pipe 310 is provided with an overflow hole 311 and a first water outlet hole 312 on both the first sedimentation tank 100 and the second sedimentation tank 200. The overflow hole 311 is provided on the first sedimentation tank 100 and the second sedimentation tank 200. The first water level is the water level when the sedimentation tank is full. The first water outlet 312 is provided at the second water level on the first sedimentation tank 100 and the second sedimentation tank 200 . The second water level is the water level when the sedimentation tank is full. The water level is the water level when the sewage in the first sedimentation tank 100 and the second sedimentation tank 200 is drained; the trigger pipe 320 is provided with a water storage tank 321, the water storage tank 321 is a blind hole, and the water storage tank 321 is along the trigger pipe 320 The axis of the water storage tank 321 is provided with a second water outlet hole 322 at the bottom of the water storage tank 321. The second water outlet hole 322 is located on the side of the trigger tube 320, and the second water outlet hole 322 is connected to the water storage tank 321. The trigger tube 320 is located in the connected Inside the tube 310; the return spring 330 is provided at the bottom of the communicating tube 310, and a contact switch is provided at the bottom of the communicating tube 310. The contact switch is a delay switch, and the contact switch automatically closes after a preset time. , the contact switch connects the switching tube drive unit 500 and the power supply; when the sewage reaches the first water level, the sewage flows into the trigger tube 320 through the overflow hole 311, the trigger tube 320 is pressed down, and the trigger tube 320 compresses the return spring 330 and the contact point The switch and the contact switch are connected to the control circuit of the switching tube driving unit 500, and the switching tube driving unit 500 controls the switching tube 400 to rotate at a preset angle;

Preferably, in order to prevent the trigger tube 320 from rotating inside the communication tube 310, the trigger tube 320 is a polygonal cylinder, and the inside of the communication tube 310 is a polygonal blind hole;

Furthermore, in order to prevent air pressure from being generated at the bottom of the communication tube 310, a pressure relief hole 313 is also provided at the bottom of the communication tube 310. The pressure relief hole 313 allows the inside of the communication tube 310 to communicate with the outside world, thereby preventing the inside of the communication tube 310 from being entangled. Pressure and tissue trigger tube 320 to drop;

The switching tube driving unit 500 includes a driving motor 510. The driving motor 510 is connected to the switching switch 300 on the first settling tank 100 and the second settling tank 200 respectively, and the switching on the first settling tank 100 and the second settling tank 200 The switch 300 controls the forward and reverse rotation of the driving motor 510 respectively. The worm 520 is fixedly connected to the output shaft of the driving motor 510. The worm gear 530 is fixedly connected to the switching tube 400. The worm 520 and the worm gear 530 are engaged. When When the driving motor 510 rotates, the driving motor 510 drives the worm 520 to rotate, the worm 520 drives the worm gear 530 to rotate, and the worm gear 530 drives the switching tube 400 to rotate;

Further, the sedimentation tank is also provided with a mounting plate 110, the driving motor 510 is fixedly connected to the mounting plate 110 through bolts, and the worm 520 is fixedly connected to the mounting plate 110 through a shaft seat 540;

Preferably, in order to prevent dust from entering the switching tube driving unit 500, a dust-proof housing 700 is set on the outside of the switching tube driving unit 500.

As another embodiment of the present invention, the multi-stage treatment device for a sewage plant also includes an alarm unit, which acts as an alarm when the water in the first sedimentation tank 100 and the second sedimentation tank 200 is full. , the alarm unit includes a first alarm module, a second alarm module and a third alarm module. The trigger switch of the first alarm module is set to the bottom of the trigger pipe 320 connected to the first sedimentation tank 100. When the first sedimentation tank 100 When the water inside is full, the trigger pipe 320 descends, the trigger switch on the trigger pipe 320 is turned on, and the first alarm device alarms. The trigger switch is a push button switch. The trigger switch of the second alarm module is located in the second sedimentation tank 200. At the bottom of the connected trigger pipe 320, the third alarm module is provided with two sets of trigger switches connected in series, and the two sets of trigger switches connected to the third alarm module are respectively located in the first sedimentation tank 100 and the second sedimentation tank 200. In the connected switch 300, the first alarm module is used to trigger an alarm when the sewage in the first sedimentation tank 100 and the second sedimentation tank 200 is full. At this time, the first sedimentation tank 100 and the second sedimentation tank 200 The sewage discharge device is faulty.

To sum up, the working principle of the present invention is:

When the sewage settles, the switching pipe 400 rotates to the first sedimentation tank 100. At this time, the right-angle elbow 410 is located above the first sedimentation tank 100. The sewage is discharged from the right-angle elbow 410 into the first sedimentation tank 100. When the When the sewage in the first sedimentation tank 100 is filled, the sewage in the first sedimentation tank 100 reaches the first water level, and the sewage in the first sedimentation tank 100 enters the connection installed on the first sedimentation tank 100 from the overflow hole 311 In the pipe 310, and flows into the water reservoir 321 in the communication pipe 310, at this time, the weight of the trigger pipe 320 increases, the trigger pipe 320 descends and presses the contact switch connected to the driving motor 510 and the first contact switch inside the communication pipe 310. The trigger switch connected to the alarm module. The first alarm module reminds the staff that the first sedimentation tank 100 is filled with sewage. The drive motor 510 rotates forward. The drive motor 510 drives the worm 520 to rotate. The worm 520 drives the worm gear 530 to rotate. The worm gear 530 drives the switching. The pipe 400 rotates, and the right-angle elbow pipe 410 rotates to the top of the second sedimentation tank 200. The sewage is poured into the second sedimentation tank 200 from the switching pipe 400. When the sewage in the first sedimentation tank 100 settles for a preset time, the staff starts The sewage discharge device provided in the first sedimentation tank 100 discharges the sewage and sludge in the first sedimentation tank 100 respectively. When the water level in the first sedimentation tank 100 reaches the second water level, the water in the trigger pipe 320 is discharged from the second water level. The second water outlet hole 322 flows out through the first water outlet hole 312, and the water in the trigger tube 320 is discharged. The trigger tube 320 rises and breaks away from the contact switch under the action of the return spring 330.

Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art will understand that various changes, modifications, and substitutions can be made to these embodiments without departing from the principles and spirit of the invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (7)

1. A multi-stage treatment device for sewage treatment plants, characterized in that it includes: Sedimentation tank, the sedimentation tank is used to settle sewage, the sedimentation tank includes a first sedimentation tank (100) and a second sedimentation tank (200), the first sedimentation tank (100) and the second sedimentation tank (200) Alternate sedimentation of sewage; Switching pipe (400), the switching pipe (400) is connected to a sewage pump, the switching pipe (400) is used to pour sewage into the first sedimentation tank (100) and the second sedimentation tank (200), the switching pipe (400) 400) is installed at one end of the sedimentation tank, and the switching pipe (400) can rotate around its own axis; A sedimentation tank switching unit, which is used to control the switching pipe (400) to inject sewage into the first sedimentation tank (100) and the second sedimentation tank (200) respectively. The sedimentation tank switching unit is fixedly connected to the sedimentation tank. One end of the switching tube (400) is provided, and the sedimentation tank switching unit is connected to the switching tube (400). The sedimentation tank switching unit includes a switching switch (300) and a switching tube driving unit (500). The switching switch (300) ) is provided with two groups, and the switch (300) is connected to one end of the first sedimentation tank (100) and the second sedimentation tank (200) respectively. The switch (300) is in the first sedimentation tank (100) or the second sedimentation tank (200). When the sewage in the second sedimentation tank (200) reaches the preset water level, the switching tube driving unit (500) is controlled to work, and the switching tube driving unit (500) controls the switching tube (400) to rotate, wherein, The switch (300) includes a communication tube (310), a trigger tube (320) and a return spring (330). The communication tube (310) is cylindrical with an opening at one end, and the communication tube (310) is fixedly connected to On the first sedimentation tank (100) and the second sedimentation tank (200), the connecting pipe (310) is provided with an overflow hole (311) and a third A water outlet (312), the overflow hole (311) is located at a first water level on the first sedimentation tank (100) and the second sedimentation tank (200), and the first water level is when the sedimentation tank is full. water level, the first water outlet hole (312) is located at the second water level on the first sedimentation tank (100) and the second sedimentation tank (200), and the second water level is between the first sedimentation tank (100) and the second sedimentation tank (200). The water level in the sedimentation tank (200) when the sewage is drained; a water storage tank (321) is provided on the trigger pipe (320), and the water storage tank (321) is arranged along the axis of the trigger pipe (320). The water storage tank (321) ) is provided with a second water outlet hole (322) at the bottom, the second water outlet hole (322) is located on the side of the trigger pipe (320), and the second water outlet hole (322) is connected with the water storage tank (321), and the trigger pipe (320) ) is located inside the communicating tube (310); the return spring (330) is located at the bottom of the communicating tube (310), and a contact switch is provided at the bottom of the communicating tube (310), and the contact switch is a delay switch, The contact switch connects the switching tube drive unit (500) and the power supply. 2. The multi-stage treatment device for sewage plants according to claim 1, characterized in that one end of the switching pipe (400) is provided with a right-angle elbow pipe (410), and the sedimentation tank is provided with a support column ( 120), the support column (120) is provided with a semicircular sinking groove, the switching tube (400) is installed on the support column (120) through the upper cover (130), the upper cover (130) is an arc plate , the upper cover (130) is fixedly connected to the support column (120). 3. The multi-stage treatment device for sewage treatment plants according to claim 2, characterized in that one end of the switching pipe (400) away from the right-angle elbow (410) is also connected to a connector (600), and the The connector (600) includes a connecting sleeve (610) and a water inlet pipe (630). The connecting sleeve (610) is cylindrical with openings at both ends. The switching pipe (400) is provided with a third pipe at one end away from the right-angled elbow (410). Two limiting rings (430). The second limiting ring (430) is located in the connecting sleeve (610). The connecting sleeve (610) is provided with an inner blocking ring at one end close to the switching tube (400). The second limiting ring (430) is 430) is clamped in the connecting sleeve (610) through the inner blocking ring, the water inlet pipe (630) is fixed to the connecting sleeve (610) through threaded fit, and the water inlet pipe (630) connects the second limiting ring (430) Press tightly on the inner retaining ring. 4. The multi-stage treatment device for sewage plants according to claim 3, characterized in that an end bearing (620) is provided between the water inlet pipe (630) and the second limiting ring (430). 5. The multi-stage treatment device for sewage plants according to claim 1, characterized in that the bottom of the communication pipe (310) is also provided with a pressure relief hole (313). 6. The multi-stage treatment device for sewage plants according to claim 1, characterized in that the switching tube driving unit (500) includes a driving motor (510), and the driving motor (510) is connected to the first settling tank respectively. (100) is connected to the switch (300) on the second sedimentation tank (200), and the switches (300) on the first sedimentation tank (100) and the second sedimentation tank (200) respectively control the driving motor (510) For forward and reverse rotation, a worm (520) is fixedly connected to the output shaft of the driving motor (510), a worm gear (530) is fixedly connected to the switching tube (400), and the worm (520) and the worm gear ( 530) Engagement. 7. The multi-stage treatment device for sewage plants according to claim 5 or 6, characterized in that the multi-stage treatment device for sewage plants further includes an alarm unit, and the alarm unit includes a first alarm module , the second alarm module and the third alarm module, the trigger switch of the first alarm module is set in the first settling tank (100) connected to the switch (300); the trigger switch of the second alarm module is set in the first sedimentation tank (100). In the switch (300) connected to the second sedimentation tank (200), the third alarm module is provided with two sets of trigger switches connected in series, and the two sets of trigger switches connected to the third alarm module are respectively located in the first sedimentation tank. (100) and the second settling tank (200) are connected to the switch (300).