CN220976699U - Urban sewage biological treatment system - Google Patents

Abstract

The utility model belongs to the technical field of sewage treatment, and provides a municipal sewage biological treatment system which comprises an aeration tank and a sedimentation tank, wherein the aeration tank is connected with the sedimentation tank; the device also comprises a driving mechanism, a paddle, an air supply device, a pipe body and an air supply nozzle; the aeration tank is provided with a mounting plate, the pipe body is rotatably mounted in the aeration tank, and the upper end of the pipe body penetrates through the mounting plate to be connected with the driving mechanism; the blade is connected with the pipe body, a cavity is formed in the blade, the cavity is communicated with the inside of the pipe body, and the air supply nozzle is connected with the blade and communicated with the cavity; the air supply device is connected with the pipe body. The utility model solves the problems that the activity of the activated sludge in each part of sewage is uneven, some sewage fully reacts with the activated sludge, and some sewage cannot fully react in the prior art.

Description

Urban sewage biological treatment system

Technical Field

The utility model belongs to the technical field of sewage treatment, and particularly relates to a biological treatment system for urban sewage.

Background

The urban biological sewage treatment system is a key device for treating various types of wastewater, and is widely applied to various fields including wastewater treatment in industries of petroleum, petrochemical, chemical, metallurgy, machinery, leather, coal gasification, food, brewing, daily chemicals, printing and dyeing, pharmacy, papermaking and the like, and sewage treatment in large-area river and lake water areas. The biological compound preparation is used as an important means for treating sewage, and can convert organic substances in the sewage into reusable biological fertilizer and biological feed, so that the effects of recycling and reducing secondary pollution are achieved.

For urban biological sewage treatment, the use of an aeration tank is a core step. Activated sludge rich in aerobic microorganisms in the aeration tank, and the microorganisms can decompose organic substances in sewage. In order to enable the microorganisms to survive and perform effective decomposition activities, air or oxygen is introduced into the aeration tank to provide necessary oxygen to meet the requirements of the survival of the microorganisms and the decomposition of organic substances. This method of utilizing microbial activity to break down organic contaminants is one of the most common and efficient ways of treating sewage today.

In the prior art, the utility model patent with publication number CN218969020U discloses a municipal sewage biological treatment system, which comprises a sedimentation tank, a biological filter tank, a sterilization tank, a sand washer and a collection bin, wherein the upper end of the left side of the sedimentation tank is provided with a water inlet pipe, the lower end of the right side of the sedimentation tank is connected with a water pumping pipe, the water pumping pipe is provided with a water pump, the tail end of the water pumping pipe is communicated with the biological filter tank, the water outlet of the biological filter tank is connected with a connecting pipe, the tail end of the connecting pipe is communicated with the sterilization tank, the bottom of the sedimentation tank is connected with a discharge pipe, and the tail end of the discharge pipe is communicated with the sand washer.

However, the above-described technique has certain limitations. For example, the gas outlet of the aeration device is usually positioned at the bottom of the tank, and the gas discharged from the aeration pipe is used for aeration treatment. However, since the aeration pipe does not cover the bottom of the tank completely during installation, the aeration pipe is generally arranged at intervals, and thus bubbles float upwards during aeration, and sewage directly above the aeration pipe can fully contact with the gas to realize oxidation. The sewage above the blank area between the aeration pipes cannot be directly influenced by the gas sprayed by the aeration pipes, and the sewage cannot be fully contacted with the gas. This results in uneven activity of the activated sludge in each portion of the sewage, some of which has reacted sufficiently with the activated sludge, and some of which has failed to react sufficiently, which affects the overall sewage treatment efficiency.

Disclosure of utility model

The utility model provides a biological treatment system for urban sewage, which aims to solve the problems in the background technology.

The utility model is realized in such a way that the municipal sewage biological treatment system comprises an aeration tank and a sedimentation tank, wherein the aeration tank is connected with the sedimentation tank; the device also comprises a driving mechanism, a paddle, an air supply device, a pipe body and an air supply nozzle; the aeration tank is provided with a mounting plate, the pipe body is rotatably mounted in the aeration tank, and the upper end of the pipe body penetrates through the mounting plate to be connected with the driving mechanism; the blade is connected with the pipe body, a cavity is formed in the blade, the cavity is communicated with the inside of the pipe body, and the air supply nozzle is connected with the blade and communicated with the cavity; the air supply device is connected with the pipe body, supplies air into the pipe body, passes through the pipe body and enters the cavity, and finally is sprayed out of the air supply nozzle.

Optionally, the driving mechanism comprises a motor, a driving sprocket, a driven sprocket and a transmission chain; the output end of the motor is connected with the driving sprocket, the driven sprocket is connected with the outer wall of the pipe body, and the transmission chain is connected between the driving sprocket and the driven sprocket in a meshed mode.

Optionally, the blade is spiral.

Optionally, the air supply device comprises a fan and an elbow; the output end of the fan is connected with the input end of the bent pipe, and the output end of the bent pipe is communicated with the pipe body and is rotationally connected with the pipe body.

Optionally, the output end of the elbow extends into the pipe body and is rotationally connected with the inner wall of the pipe body through a bearing.

Optionally, a guard rail is arranged on the upper surface of the mounting plate; the mounting plate is also connected with a ladder, and the ladder is fixedly connected with the outer wall of the aeration tank.

Optionally, the air supply nozzle comprises an air supply pipe, a sphere, a sealing ring and a limiting frame; the air supply pipe is connected with the blade and communicated with the cavity, the ball body, the sealing ring and the limiting frame are respectively arranged in the air supply pipe, and the ball body is positioned between the sealing ring and the limiting frame; the limiting frame is positioned at one end of the air supply pipe far away from the blade; the movable distance of the sphere is formed between the limiting frame and the sealing ring; the internal diameter of sealing washer is less than the diameter of spheroid, the spacing is used for to the spheroid is spacing, prevents the spheroid from by move away in the air supply pipe.

Optionally, an arc surface matched with the sphere is arranged on the sealing ring, and a circular notch is arranged in the center of the limiting frame.

Optionally, the aeration tank is connected with first water pipe, the one end that first water pipe kept away from the aeration tank is connected with the input of pump machine, the output of pump machine is connected with the second water pipe, the second water pipe keep away from the one end of pump machine with the top of sedimentation tank corresponds.

The utility model has the beneficial effects that when the driving mechanism drives the pipe body and the paddles connected with the pipe body to rotate, the air supply device synchronously transmits oxygen into the pipe body. The oxygen then enters the cavity in the blade through the pipe body and finally is sprayed out by the air supply nozzle. Because the air supply nozzle is connected with the paddle, the air supply nozzle can also perform circular motion in the rotating process of the paddle. The design not only ensures that oxygen can be released in a wide area of the aeration tank, but also ensures that the oxygen release and the stirring of the water body are synchronous due to the synchronous stirring and air injection, thereby further enhancing the dissolution and dispersion of the oxygen in the water.

The synchronous stirring and oxygen supply mode enhances the oxidation environment of the water body and improves the utilization rate of oxygen, so that the aerobic microorganisms can decompose organic matters in the sewage more effectively, and the efficiency of wastewater treatment is improved. Meanwhile, through the stirring effect of the blades, the sedimentation and aggregation of the activated sludge are prevented, the suspended state of the sewage and the sludge is maintained, and the normal operation of the aeration tank is ensured. The utility model further solves the problems that the activity of the activated sludge in each part of sewage is uneven, some sewage fully reacts with the activated sludge, and some sewage cannot fully react in the prior art.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic perspective view of a biological municipal sewage treatment system according to the utility model;

FIG. 2 is a schematic diagram of the structure of an aeration tank of the municipal sewage biological treatment system according to the utility model;

FIG. 3 is an exploded view of an aeration tank of the municipal sewage biological treatment system according to the utility model;

FIG. 4 is a schematic view of an aeration tank of the municipal sewage biological treatment system according to the utility model, comprising a guard rail and a ladder;

FIG. 5 is a schematic perspective view of a driving mechanism of the municipal sewage biological treatment system according to the utility model;

FIG. 6 is a perspective view and an exploded view of an air supply nozzle of the municipal sewage biological treatment system provided by the utility model;

Fig. 7 is a schematic cross-sectional structural view of a pipe body and a blade of the municipal sewage biological treatment system provided by the utility model.

The reference numerals are as follows:

1-aeration tank, 11-mounting plate, 12-rail guard, 13-ladder, 14-first water pipe, 2-sedimentation tank, 21-second water pipe, 3-actuating mechanism, 31-motor, 32-driving sprocket, 33-driven sprocket, 34-driving chain, 4-paddle, 41-cavity, 5-air feeder, 51-fan, 52-return bend, 6-body, 61-bearing, 7-air feed mouth, 71-air feed pipe, 72-spheroid, 73-sealing washer, 731-cambered surface, 74-spacing, 741-circular notch, 8-pump.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to fall within the scope of the application.

The terms "first" and "second" and the like in this disclosure are used for distinguishing between different objects and not for describing a particular sequential order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps, operations, components, or modules is not limited to the particular steps, operations, components, or modules listed but may optionally include additional steps, operations, components, or modules inherent to such process, method, article, or apparatus.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

As shown in fig. 1 to 7, an exemplary embodiment of the present invention provides a municipal sewage biological treatment system comprising an aeration tank 1 and a sedimentation tank 2, wherein the aeration tank 1 and the sedimentation tank 2 are connected to each other.

The system further comprises a driving mechanism 3, a blade 4, an air supply device 5, a pipe body 6 and an air supply nozzle 7. The upper part of the aeration tank 1 is provided with a mounting plate 11, the pipe body 6 is rotatably arranged in the aeration tank 1, and the upper end of the pipe body passes through the mounting plate 11 and is connected with the driving mechanism 3. The blade 4 is connected with the pipe body 6, and the inside of the blade 4 is provided with a cavity 41 and is communicated with the inside of the pipe body 6. The air supply nozzle 7 is connected to the blade 4 and communicates with the cavity 41. The air supply device 5 is connected with the pipe body 6, and the air supply device 5 is responsible for delivering air into the pipe body 6, delivering the air to the cavity 41 through the pipe body 6, and finally being sprayed out by the air supply nozzle 7.

Specifically, the driving mechanism 3 is used for driving the tube body 6 to rotate, and the air supply device 5 is responsible for supplying air to the interior of the tube body 6. The air contains a certain amount of oxygen, so that the air is delivered to the tube body 6 and the oxygen is delivered at the same time. In use, the drive mechanism 3 drives the rotation of the tube 6 such that the paddles 4 connected to the tube 6 rotate therewith. The rotation of the blades 4 can generate a stirring effect on the water in the aeration tank 1, so that the water in the aeration tank 1 keeps a rolling state. Simultaneously, the air supply device 5 conveys air into the pipe body 6, the air enters the cavity 41 through the pipe body 6, then enters the air supply nozzle 7 from the cavity 41, and is sprayed into the aeration tank 1 through the air supply nozzle 7.

In the process, the air supply nozzle 7 performs circular motion along with the rotation of the blade 4, so that oxygen is continuously supplied in the process of water body tumbling. The stirring action of the blades 4 can improve the solubility and the distribution uniformity of the oxygen, so that the microorganisms can better utilize the oxygen, and the decomposition efficiency of the organic substances is improved.

In this embodiment, the release of oxygen and the movement of the blades are synchronized, which is advantageous in that it greatly enhances the sufficient dissolution and dispersion of oxygen in water.

When the driving mechanism 3 drives the pipe body 6 and the blade 4 connected thereto to rotate, the air supply device 5 synchronously supplies oxygen to the inside of the pipe body 6. The oxygen then enters the cavity 41 in the blade 4 through the tube 6 and is finally ejected by the air supply nozzle 7. Since the air supply nozzle 7 is connected with the blade 4, the air supply nozzle 7 also performs circular motion during the rotation of the blade 4. The design not only ensures that oxygen can be released in a wide area of the aeration tank 1, but also ensures that the oxygen release and the stirring of the water body are synchronous due to the synchronous stirring and air injection, thereby further enhancing the dissolution and dispersion of the oxygen in the water.

The synchronous stirring and oxygen supply mode enhances the oxidation environment of the water body and improves the utilization rate of oxygen, so that the aerobic microorganisms can decompose organic matters in the sewage more effectively, and the efficiency of wastewater treatment is improved. Meanwhile, through the stirring effect of the blades 4, the sedimentation and aggregation of the activated sludge are prevented, the suspended state of the sewage and the sludge is maintained, and the normal operation of the aeration tank 1 is ensured.

As an alternative embodiment, the drive mechanism 3 includes a motor 31, a drive sprocket 32, a driven sprocket 33, and a transmission chain 34. The output end of the motor 31 is connected with a driving sprocket 32, and a driven sprocket 33 is connected with the outer wall of the pipe body 6. The drive chain 34 is engaged between the drive sprocket 32 and the driven sprocket 33, and power transmission is achieved. Specifically, the motor 31 is fixedly connected to the mounting plate 11 through a connector (not explicitly shown), and the driving sprocket 32 is also rotatably connected to the mounting plate 11 through an existing connector (not explicitly shown). In the actual use process, after the motor 31 is started, the output end of the motor drives the driving sprocket 32 to rotate, and the rotation of the driving sprocket 32 drives the driven sprocket 33 to rotate through the transmission chain 34. Because the driven sprocket 33 is connected with the outer wall of the pipe body 6, the rotation of the driven sprocket 33 can drive the pipe body 6 and the paddles 4 thereon to rotate, and the stirring of the aeration tank 1 is realized. It should be noted that, the specific assembly manner and the layout of each component may be adjusted according to the actual requirement of production and manufacture, which is not described herein.

As an alternative embodiment, the number of the blades 4 is set to three, and the shape of the blades 4 is designed to be spiral. This design allows the blades 4 to more thoroughly agitate the water in the aeration tank 1 as it rotates, while helping to disperse the gas more evenly in the water. Further, in order to improve the uniformity of the distribution of oxygen in the aeration tank, at least one air supply nozzle 7 is provided on each spiral-shaped blade 4. When the air supply device 5 transmits oxygen into the pipe body 6, the oxygen is evenly sprayed out through the pipe body 6 and the inner cavity 41 of the blade 4 and finally through the air supply nozzle 7, so that the oxygen is efficiently utilized and evenly distributed.

As an alternative embodiment, the air supply device 5 comprises a fan 51 and a bent pipe 52. The output end of the fan 51 is connected with the input end of the bent pipe 52, and the output end of the bent pipe 52 is connected with the pipe body 6 and is in rotary connection with the pipe body 6. The fan 51 is fixed to a mounting seat on the mounting plate 11, and in use, the fan 51 will deliver air into the interior of the pipe body 6 through the elbow 52. The air then enters the cavity 41 of the blade 4 and is eventually ejected through the air supply nozzle 7. It should be noted that the air ejected contains a certain amount of oxygen, so that the oxygen is ejected simultaneously with the air being ejected through the air nozzle 7.

As an alternative embodiment, the outlet end of the bent tube 52 protrudes into the interior of the tube body 6 and is rotatably connected to the inner wall of the tube body 6 by means of a bearing 61. In the process of driving the pipe body 6 to rotate by the driving mechanism 3, the pipe body 6 rotates relative to the bent pipe 52. The design of the bearing 61 can effectively reduce friction, so that the system can run more smoothly, and the durability and the working efficiency of the equipment are improved.

As an alternative embodiment, referring to fig. 4, a guard rail 12 is provided on the upper surface of the mounting plate 11; the mounting plate 11 is also connected with a ladder 13, and the ladder 13 is fixedly connected with the outer wall of the aeration tank 1. The guard rail 12 is used to prevent persons working on the mounting plate 11 from inadvertently falling into the aeration tank 1. The ladder 13 is set so that a person climbs the mounting plate 11 to facilitate maintenance and repair of the driving mechanism 3 and the air supply device 5 on the mounting plate 11, and also to facilitate observation of changes in sewage in the aeration tank 1 on the mounting plate 11.

As an alternative embodiment, the air supply nozzle 7 is composed of an air supply pipe 71, a ball 72, a sealing ring 73 and a stopper 74. The air supply pipe 71 is connected to the blade 4 and communicates with the cavity 41 thereof. The ball 72, the sealing ring 73 and the stopper 74 are all installed inside the gas supply pipe 71, wherein the ball 72 is located between the sealing ring 73 and the stopper 74. The limiting frame 74 is located at one end of the air supply pipe 71 far away from the blade 4, and a movable section of the sphere 72 is formed between the limiting frame 74 and the sealing ring 73. The inner diameter of the sealing ring 73 is smaller than the diameter of the sphere 72, so that the stop 74 prevents the sphere 72 from moving out of the gas supply pipe 71.

In a normal state, the balls 72 fall on the sealing rings 73 due to the gravity, and at the same time, water in the aeration tank 1 enters from the upper end of the air supply pipe 71, and a certain pressure is generated to the balls 72. At this time, the ball 72 is in close contact with the sealing ring 73, and water in the aeration tank 1 cannot enter the air supply pipe 71, effectively preventing sewage in the aeration tank 1 from entering the cavity 41.

During the air filling process in the aeration tank 1, the air pressure acts to float the sphere 72 upward and contact the stopper 74. At this time, a gap is formed between the ball 72 and the seal ring 73, and air is discharged from the gap and enters the aeration tank 1 for gas exchange. Since the air is continuously discharged, water in the aeration tank 1 can be prevented from entering the cavity 41 through the air supply pipe 71.

In the present embodiment, the floating principle of the sphere 72 is as follows: when air is filled into the aeration tank 1, the air supply device 5 supplies air from the fan 51 into the pipe body 6, and the air enters the cavity 41 of the blade 4 through the inside of the pipe body 6. Subsequently, the air flows toward the sphere 72 through the inlet of the air supply pipe 71.

During the flow of air to ball 72, a lower pressure zone is created around ball 72 due to the velocity and flow of air, and this lower pressure zone causes a pressure differential such that ball 72 moves away from the contact surface of seal 73. On the one hand, the lift force generated by this pressure difference and, on the other hand, the air flow in the air supply tube 71 will generate a pushing force on the sphere 72, which forces act together so that the sphere 72 floats up in the air supply tube 71. When the ball 72 floats up to contact the limit 74, a gap is formed between the ball 72 and the seal 73, and air in the air supply pipe 71 can be discharged from the gap to enter the aeration tank 1.

Therefore, the sphere floating mechanism of the present embodiment is determined by the flow rate and flow rate of air and the pressure difference generated thereby, and this mechanism is ensured by the laws of physics, and will not be described in detail herein.

As an alternative embodiment, the sealing ring 73 is provided with a cambered surface 731 corresponding to the sphere 72, and the middle part of the limiting frame 74 is provided with a circular notch. Through the design of the cambered surface 731, the spherical body 72 can be matched better, and when the spherical body 72 is in contact with the cambered surface 731 of the sealing ring 73, the sealing effect can be improved, and water from the aeration tank 1 is effectively prevented from entering the cavity 41 through the air supply nozzle 7.

As an alternative embodiment, the aeration tank 1 is provided with a first water pipe 14, one end of the first water pipe 14 is far away from the aeration tank 1 and is connected to the input end of the pump 8, the output end of the pump 8 is connected to a second water pipe 21, and one end of the second water pipe 21 is far away from the pump 8 and corresponds to the upper part of the sedimentation tank 2. In a specific operation, after the pump 8 is started in the aeration tank 1, the pump 8 sucks water in the aeration tank 1 through the first water pipe 14 and conveys the water to the second water pipe 21, and then discharges the water to the sedimentation tank 2 through the second water pipe 21 for sedimentation. Thus, the sewage after aeration treatment can be further precipitated in the sedimentation tank 2, thereby realizing effective treatment of urban sewage.

In the prior art, due to the influences of factors such as the size of bubbles, the distribution of the bubbles in water, the suspension time of the bubbles in water and the like, the contact between the activated sludge in the sewage and the oxygen may be uneven, so that some sewage fully reacts with the activated sludge, and some sewage does not fully react.

The aeration device is driven by the spiral blades in the pipe body, and when the blades are rotated, sewage is driven to synchronously rotate, so that rotational flow is formed. The rotational flow state can enable the activated sludge and bubbles in the sewage to be mixed more fully, so that the distribution uniformity of oxygen in the sewage is improved, the contact between the activated sludge and the oxygen is more uniform, and the efficiency of the activated sludge on sewage treatment is improved.

In addition, the utility model also designs a special air supply nozzle 7, the sphere 72 in the structure of the air supply nozzle 7 can float upwards under the action of air pressure to form a gap, so that air can smoothly pass through and be sprayed out, and meanwhile, when no pressure exists, the sphere can fall back and block the air supply nozzle, thereby effectively preventing sewage from flowing back into the paddle cavity 41, and further ensuring that the air can be uniformly and continuously supplied into the sewage.

In the current environmental protection context, municipal sewage treatment becomes a very important issue. The utility model is suitable for urban environment, and is mainly used for treating urban domestic sewage or urban industrial sewage. Such sewage is produced by human life and industrial production activities, and contains a large amount of organic substances, inorganic substances, germs and other pollutants. If the raw materials are directly discharged, serious pollution is caused to the environment. Accordingly, the present utility model is directed to solving the problem of sewage treatment in urban environments. Of course, the technical scheme of the utility model is not limited to cities, and can be understood as a sewage biological treatment system.

The term "living beings" in the urban sewage biological treatment system mainly refers to a biological treatment process. The technology mainly utilizes the biological activity of microorganisms to convert organic matters in the sewage into microorganism constitution and water, thereby removing pollutants in the sewage. In the sewage treatment process, oxygen is supplied to the sewage through the air supply nozzle 7, and oxygen required by microorganism growth is provided. Under the aerobic condition, the microorganism can oxidize and decompose organic substances in the sewage to generate harmless carbon dioxide and water, and can generate new microorganism cells to realize the biodegradation of harmful substances in the sewage. Therefore, the technical method of the utility model utilizes biotechnology to treat sewage, improves the sewage treatment efficiency and reduces environmental pollution.

The exemplary embodiments of the present application may be combined with each other, and exemplary embodiments obtained by combining also fall within the scope of the present application.

The principles and embodiments of the present application have been described with reference to specific examples, which are provided to facilitate understanding of the method and core ideas of the present application; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in light of the ideas of the present application, the present description should not be construed as limiting the present application.

Claims (8)

1. The urban sewage biological treatment system comprises an aeration tank (1) and a sedimentation tank (2), wherein the aeration tank (1) is connected with the sedimentation tank (2); the device is characterized by further comprising a driving mechanism (3), a paddle (4), an air supply device (5), a pipe body (6) and an air supply nozzle (7); the aeration tank (1) is provided with a mounting plate (11), the pipe body (6) is rotatably arranged in the aeration tank (1), and the upper end of the pipe body (6) penetrates through the mounting plate (11) to be connected with the driving mechanism (3); the blade (4) is connected with the pipe body (6), a cavity (41) is formed in the blade (4), the cavity (41) is communicated with the inside of the pipe body (6), and the air supply nozzle (7) is connected with the blade (4) and is communicated with the cavity (41); the air supply device (5) is connected with the pipe body (6), and the air supply device (5) supplies air into the pipe body (6), and enters the cavity (41) through the pipe body (6), and finally is sprayed out by the air supply nozzle (7).

2. The urban sewage biological treatment system according to claim 1, characterized in that said blades (4) are helical.

3. The urban sewage biological treatment system according to claim 1, characterized in that said air supply means (5) comprise a blower (51) and an elbow (52); the output end of the fan (51) is connected with the input end of the bent pipe (52), and the output end of the bent pipe (52) is communicated with the pipe body (6) and is rotationally connected with the pipe body (6).

4. A municipal sewage biological treatment system according to claim 3, wherein the output end of the elbow (52) extends into the interior of the pipe body (6) and is rotatably connected to the inner wall of the pipe body (6) by means of a bearing (61).

5. The municipal sewage biological treatment system according to claim 1, wherein a guard rail (12) is provided on the upper surface of the mounting plate (11); the mounting plate (11) is also connected with a ladder (13), and the ladder (13) is fixedly connected with the outer wall of the aeration tank (1).

6. The municipal sewage biological treatment system according to claim 1, wherein the air supply nozzle (7) comprises an air supply pipe (71), a sphere (72), a sealing ring (73) and a limiting frame (74); the air supply pipe (71) is connected with the blade (4) and is communicated with the cavity (41), the ball body (72), the sealing ring (73) and the limiting frame (74) are respectively arranged in the air supply pipe (71), and the ball body (72) is positioned between the sealing ring (73) and the limiting frame (74); the limiting frame (74) is positioned at one end of the air supply pipe (71) far away from the blade (4); a movable distance of the sphere (72) is formed between the limiting frame (74) and the sealing ring (73); the inner diameter of the sealing ring (73) is smaller than the diameter of the sphere (72), and the limiting frame (74) is used for limiting the sphere (72) and preventing the sphere (72) from moving out of the air supply pipe (71).

7. The municipal sewage biological treatment system according to claim 6, wherein the sealing ring (73) is provided with a cambered surface (731) matching with the sphere (72).

8. The municipal sewage biological treatment system according to claim 1, wherein the aeration tank (1) is connected with a first water pipe (14), one end of the first water pipe (14) away from the aeration tank (1) is connected with an input end of a pump (8), an output end of the pump (8) is connected with a second water pipe (21), and one end of the second water pipe (21) away from the pump (8) corresponds to the upper part of the sedimentation tank (2).