Anaerobic tank gas stirring method for sewage treatment

Abstract

In order to solve the problems that in the prior art, when a gas stirring device is adopted for stirring an anoxic tank, dissolved oxygen is likely to exceed the standard, only vertical stirring is adopted, dead zones are likely to be generated, and sludge and water are not fully mixed, the invention provides a gas stirring method for the anoxic tank for sewage treatment. And meanwhile, gas is intermittently supplied to the gas stirring pipe, and the gas inlet amount of the stirred gas is controlled, so that a good stirring effect can be realized only by introducing a small amount of gas into the anoxic tank, and the problem that the dissolved oxygen amount exceeds the standard due to excessive introduced gas is solved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to an anoxic pool gas stirring method for sewage treatment. Background Art

[0002] At present, in the domestic integrated treatment equipment, the biochemical part of sewage treatment is mainly divided into anaerobic tanks, anoxic tanks, and aerobic tanks. In order to make the water quality more uniform and prevent the biochemical sludge from depositing on the bottom of the tank and affecting the treatment effect, all kinds of tanks need to be stirred. The dissolved oxygen content of the anoxic tank is 0.2-0.5mg / L. When treating sewage, mechanical stirring devices and gas stirring devices are usually used to stir the water in the anoxic tank. When stirring with mechanical stirring devices, submersible stirrers are generally used. However, due to the small volume of the integrated equipment tank, there is no matching small submersible stirring equipment on the market. The rated power of the existing stirring equipment is much higher than the use requirements. The stirring device is not only expensive and has a large rated power, but also increases unnecessary power consumption, has high movement costs, and has a high failure rate and short service life for underwater operation motors. When using a gas stirring device for stirring, the water is stirred by ventilating the water underwater through the gas stirring pipeline. Its working principle is as follows: Since the pressure of the liquid at the bottom of the pool is greater than the pressure of the liquid on the upper part of the pool body, when the gas is ventilated to the bottom of the pool, the gas moves upward from the bottom of the pool. During the upward movement of the gas, the bubbles continue to grow or burst, driving the water flow, thereby stirring the sewage in the pool. When using a gas stirring device for stirring, since air needs to be filled into each pool, although it can save energy and reduce costs, it is very easy to cause the dissolved oxygen in the anoxic pool to exceed the standard. Moreover, since the bubbles rise vertically, only the stirring zone is formed in the vertical direction. The stirring direction is single, and it is easy to produce a stirring dead zone, resulting in insufficient mixing between the sludge and the water, which leads to unsatisfactory treatment effect during sewage treatment. Summary of the invention

[0003] The purpose of the present invention is to provide a gas stirring method for anoxic tanks for sewage treatment, aiming at the problem that in the prior art, when a gas stirring device is used to stir the anoxic tank, the dissolved oxygen in the anoxic tank is easily exceeded, and the gas can only be stirred vertically, and the sludge and water are not mixed sufficiently, which leads to unsatisfactory treatment effect when the sewage is treated.

[0004] The objective of the present invention is achieved through the following technical solutions: A gas stirring method for anoxic tanks for sewage treatment, wherein the gas discharged from the gas outlet of the gas stirring pipe flows horizontally and vertically, stirring the sewage in both horizontal and vertical directions; The anoxic tank is aerated intermittently. When the sludge and water are mixed, the aeration is stopped. When the sludge and water are about to be completely separated, the aeration is repeated intermittently to keep the sludge and water in a mixed state. The diameter of the exhaust hole is 3-8mm, the center distance of the exhaust hole is 100-500mm, the inflation pressure is 1-2.5 times the water pressure of the water level where the exhaust hole is located, the inflation time is 1-5 minutes and the interval is 15-30 minutes, and the air intake in the air stirring pipe is 0.01-0.05m³ / ㎡*min; When it is necessary to discharge the sludge in the air stirring pipe, a sludge discharge port is provided below the air stirring pipe, the size of which is larger than the diameter of the air outlet, and a pressure greater than the working air pressure is charged into the air stirring pipe, so that the sludge is discharged from the sludge discharge port below the air stirring pipe; the diameter of the sludge discharge port is 15-25 mm, and a plurality of sludge discharge ports are arranged at intervals on the lower pipe wall of the air stirring pipe, or an open sludge discharge port is arranged on each section of the air stirring pipe along the length of each section of the air stirring pipe; The following structure is used for stirring the anoxic pool gas stirring device for sewage treatment: the anoxic pool gas stirring device for sewage treatment comprises an air stirring pipe, which is a closed pipe, and an exhaust hole is arranged on the wall of the air stirring pipe. When the air stirring pipe is located at the working position, the opening of the exhaust hole faces upward, and a guide plate is obliquely arranged above the opening of the exhaust hole. The distance between one end of the guide plate and the air stirring pipe is smaller than the distance between the other end and the air stirring pipe, and the gas discharged from the exhaust hole is blocked by the guide plate; The exhaust holes are arranged on the left half wall and the right half wall of the air stirring tube along the axial direction of the air stirring tube. The exhaust holes on the left half wall and the exhaust holes on the right half wall are arranged opposite to each other or staggered in sequence. When they are arranged opposite to each other, the center lines of the two exhaust holes are on the same cross section of the air stirring tube; when they are staggered, the exhaust holes on the left / right half wall correspond to the middle positions of the two exhaust holes on the right / left half wall. The angle between the center line of the exhaust hole and the vertical plane is 15°-55°, the aperture of the exhaust hole is 3-8mm, the distance between two adjacent exhaust holes along the axis of the gas stirring tube is 100-500mm, the exhaust holes on the left half wall correspond to the guide pieces with the same inclination direction, and the exhaust holes on the right half wall correspond to the guide pieces with the same inclination direction and opposite to the inclination direction of the guide pieces on the left half wall; The gas stirring tube includes a main tube and a branch tube, one end of the main tube is closed, and the other end is connected to the gas source through the air inlet tube, the branch tube is arranged on the side of the main tube, one end is connected to the main tube, and the other end is closed, the exhaust hole is arranged on the tube wall of the branch tube, and the tube center lines of each branch tube are located in the same plane; or, the gas stirring tube includes an annular tube, the annular tube is connected to the gas source through the air inlet tube, and a connecting pipe is arranged in the cavity of the annular tube, and the connecting pipe is connected to the annular tube; A mud discharge port 1 opening downward is provided on the main pipe, and the mud discharge port 1 is provided along the length direction of the main pipe, and the opening direction of the mud discharge port is provided in the opposite direction to the opening direction of the exhaust hole and is larger than the opening size of the exhaust hole; or, the cross section of the position where the mud discharge port 1 is provided on the main pipe is an inverted U-shape with an open bottom; A second mud discharge port opening downward is provided on the lower pipe wall of the air stirring pipe corresponding to the position between two adjacent air discharge holes; A solenoid valve is provided at one end of the air inlet pipe close to the compressed air source, and the intermittent opening and closing of the air inlet pipe is controlled by the solenoid valve. When the solenoid valve is opened, the sludge and water begin to mix. When the solenoid valve is closed, the sludge and water stop mixing and separate. The solenoid valve is opened again when the sludge and water are completely separated or before they are completely separated.

[0005] By adopting the stirring method provided by the present invention, the flow direction of the stirring gas is guided to generate lateral and longitudinal flows. At the same time, the gas is intermittently supplied to the gas stirring tube to control the gas intake amount of the stirring gas, so that a good stirring effect can be achieved by only introducing a small amount of gas into the anoxic pool, thereby solving the problem of excessive dissolved oxygen caused by excessive introduction of gas.

[0006] The anoxic pool gas stirring method for sewage treatment provided by the present invention is adopted, and the anoxic pool gas stirring device for sewage treatment is adopted for stirring. Since a guide piece is arranged on the gas stirring pipe, and the guide piece is arranged obliquely above the outlet of the exhaust hole, when the gas is discharged from the exhaust hole, the guide piece blocks the rising path of the gas, and changes the rising trajectory of the gas. Under the action of the guide piece, the gas produces two movement directions, namely, horizontal and vertical. The horizontally moving gas drives the water flow to flow horizontally within a certain range, and the vertically moving gas drives the water flow to flow vertically. In this way, a horizontal stirring zone runs through the vertical stirring zone, and the horizontally flowing water flow and the vertically flowing water flow are intertwined with each other, so that the sludge and water are fully stirred, the dead zone in the vertical stirring zone is eliminated, the stirring uniformity of the sludge and water is enhanced, and the sewage treatment effect is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic diagram of a top view of an embodiment of an anoxic tank gas stirring device for sewage treatment according to the present invention; Figure 2 for Figure 1 AA section view schematic diagram; Figure 3 for Figure 1 BB section view schematic diagram; Figure 4 It is a schematic top view of another embodiment of the anoxic tank gas stirring device for sewage treatment of the present invention; Figure 5 It is an isometric view of the structure of an embodiment of the present invention.

[0008] Description of Reference Numerals 1. Solenoid valve; 2. Air inlet pipe; 3. Anoxic tank; 4. Main pipe; 41. Mud discharge port 1; 5. Branch pipe; 51. Exhaust hole; 52. Mud discharge port 2; 6. Guide plate; 7. Support rod; 8. Fixed frame; 9. Ring pipe; 91. Connecting pipe fittings; 11. Air stirring pipe.

[0009] The present invention will be further described below in conjunction with specific embodiments: The present invention provides an anoxic tank gas stirring device for sewage treatment, such as Figure 1-Figure 5 As shown, it includes an air stirring pipe 11, an air intake pipe 2, an electromagnetic valve 1 and a compressed air source (not shown) arranged outside the anoxic pool 3. The air stirring pipe 11 is a closed pipeline, generally arranged horizontally at the bottom of the anoxic pool 3. The air stirring pipe is connected to the compressed air source through the air intake pipe 2. The electromagnetic valve 1 is arranged on one end of the air intake pipe 2 close to the compressed air source, and the opening and closing of the air intake pipe 2 is controlled by the electromagnetic valve 1.

[0010] The two ends of the gas stirring tube are closed, and a plurality of exhaust holes are arranged on the tube wall. The outlet of the exhaust hole 51 is vertically upward or inclined upward, preferably inclined upward, that is, the exhaust hole 51 is arranged in the upper half of the gas stirring tube to facilitate gas discharge. Preferably, the exhaust holes are arranged on the left half wall and the right half wall of the gas stirring tube, the outlet of the exhaust hole on the left half wall is inclined to the upper left, and the outlet of the exhaust hole on the right half wall is inclined to the upper right, the inclination angle a between the exhaust hole and the vertical plane is between 15°-55°, the aperture of the exhaust hole is preferably 3-8mm, and the center distance between two adjacent exhaust holes along the axis of the gas stirring tube is between 100-500mm, preferably 200-500mm. The exhaust holes on the left half wall and the right half wall can be arranged relatively, or staggered. When arranged relatively, the center lines of the two relative exhaust holes are on the same cross section of the gas stirring tube. When staggered, the exhaust holes on the left / right half wall correspond to the middle position of the two adjacent exhaust holes on the right / left half wall.

[0011] An inclined guide piece 6 is correspondingly arranged above each exhaust hole 51, and one end of the guide piece can be fixedly connected to the outer wall of the gas stirring tube, and the other end is a free end. The guide piece is inclined along the axial direction of the gas stirring tube or in a direction perpendicular to the axis of the gas stirring tube, or at any angle. The inclination angle of the guide piece corresponding to each exhaust hole on the left half wall or the right half wall of the gas stirring tube may be different, but the inclination direction is preferably consistent, and the inclination direction of the guide piece corresponding to the exhaust hole on the left half wall and the right half wall is opposite.

[0012] The preferred structure provided by the present invention is: the exhaust holes on the left half wall and the right half wall are arranged oppositely, the two guide plates corresponding to the two oppositely arranged exhaust holes are inclined in a direction perpendicular to the axis of the gas stirring tube, the two guide plates are fixedly connected to the tube wall through the same support rod 7, the height of the support rod 7 is preferably 50-200mm, the center line angle 2α of the two oppositely arranged exhaust holes is 90°, and the angle β between the two guide plates is 100°. In this structure, the gas discharged from the oppositely arranged exhaust holes moves laterally in two completely opposite directions under the action of the guide plates, and the bubbles formed are guided to a farther distance by the guide plates during the rising process, effectively preventing the bubbles discharged from the two exhaust holes from colliding.

[0013] The gas stirring tube can be set in various shapes or structures. For example, it can include only one pipeline, which can be in a straight line, a curve, a broken line, etc., or it can include multiple pipelines, and the multiple pipelines can be connected to each other with different connection structures.

[0014] Regarding the structure of the gas stirring tube, the present invention provides the following two embodiments for reference: Embodiment 1: It includes a main pipe 4 and a branch pipe 5. The main pipe 4 is preferably a rectangular pipe. One end of the main pipe 4 is connected to the air inlet pipe 2 and the other end is closed. The branch pipes 5 are horizontally arranged on both sides of the main pipe 4, one end is connected to the main pipe 4 and the other end is closed. Multiple branch pipes 5 can be arranged on each side of the main pipe 4. The branch pipes 5 on both sides can be staggered or symmetrically arranged. The axis of the branch pipe 5 and the main pipe 4 can be vertical or inclined at a certain angle, preferably vertically arranged. The spacing between the branch pipes on the same side is preferably 300-500mm. The exhaust hole 51 can be arranged on the main pipe and the branch pipe, preferably only on the branch pipe 5. The main pipe and the branch pipe can be arranged in a straight line, a curve, a broken line, etc.

[0015] Embodiment 2: Figure 4 As shown, it includes an annular tube 9, which is connected to the air intake pipe 2. A connecting pipe 91 is arranged in the annular space of the annular tube, and both ends of the connecting pipe are connected to the annular tube. The annular tube can be a rectangular ring, a circular ring or an elliptical ring. Preferably, the annular tube 9 is rectangular. It is best that the connecting pipe 91 evenly divides the annular space of the annular tube, and the exhaust hole 51 is arranged on the annular tube 9 and the connecting pipe 91. The connecting pipe 91 can be provided with one or more. When multiple connecting pipes are provided, the connecting pipes can be parallel to each other or intersect in a grid shape. The distance between the annular tube 9 and the adjacent connecting pipe 91, and between adjacent connecting pipes, is preferably 300-1000mm.

[0016] Of course, when an annular tube is included, multiple annular tubes can also be arranged in a concentric circle structure, and the annular tubes are interconnected by connecting pipes, and each annular tube and / or connecting pipe can be provided with an exhaust hole.

[0017] During operation, the main pipe 4 or the annular pipe 9 is fixed to the bottom of the anoxic pool 3 through the fixing frame 8, the solenoid valve 1 is opened, and the compressed air enters the gas stirring pipe and is discharged from the exhaust hole to stir the sewage. Because the density of gas is less than the density of water, and because there is a pressure difference between the upper and lower liquid levels in the sewage pool, the pressure of the upper liquid level is less than the pressure of the lower liquid level, and the discharged gas moves vertically upward. However, since a guide piece 6 is obliquely arranged above the outlet of the exhaust hole, the gas collides with the guide piece 6 during the rising process, and the guide piece 6 generates a reverse force on the rising gas. Under this reverse force, the gas moves in both the horizontal and vertical directions. A part of the gas moves horizontally for a distance, and another part of the gas continues to move vertically upward after bypassing the free end of the guide piece 6. The gas moving laterally drives the local water flow to flow laterally, realizing horizontal stirring in the local area. The gas moving laterally will eventually move vertically upward to carry out longitudinal stirring. Therefore, the gas discharged from the same exhaust hole 51 is first stirred in the local area in the horizontal and longitudinal directions under the action of the guide plate 6, and then two longitudinal stirring areas are formed in the longitudinal direction. This not only increases the stirring area, but also makes the stirring more sufficient, thereby achieving the purpose of achieving a better stirring effect with a small amount of gas.

[0018] Furthermore, the solenoid valve 1 is used to intermittently supply air to the gas stirring tube, and the air intake is controlled by controlling the air intake intensity and time. The output pressure of the gas source is preferably 1-2.5 times the water pressure of the water level at the exhaust hole, and the air intake in the gas stirring tube is preferably 0.01-0.05m³ / ㎡*min. The aeration time in the anoxic tank is preferably 1-5 minutes, and the interval time is preferably 10-30 minutes, that is, every 10-30 minutes, the gas is inflated for 1-5 minutes. Within 1-5 minutes of inflation, the gas fully mixes the sewage, and within 10-30 minutes of stopping inflation, the sludge and water are gradually separated. The air intake operation is performed before the water and sludge are completely separated. This not only ensures the stirring effect, but also can achieve the dissolved oxygen content under 0.5mg / L while ensuring the stirring effect. However, when inflation stops in the gas stirring tube, the sewage will enter the gas stirring tube under the action of water pressure and block the inner cavity of the tube. In order to prevent the inner cavity of the air stirring pipe from being blocked by sludge, a mud discharge port opening vertically downward is provided on the air stirring pipe.

[0019] In the first embodiment, a mud discharge port 1 41 is provided at the lower end of the main pipe 4, and a mud discharge port 2 52 is provided at the lower end of the branch pipe 5. The mud discharge port 1 41 can be provided in multiple discontinuous positions along the length direction of the main pipe 4, or the bottom of the main pipe 4 can be completely opened to be open, that is, the main pipe 4 is in an inverted U-shape at the bottom. The mud discharge port 2 52 can be provided in multiple positions along the length direction of the branch pipe 5, preferably between two adjacent pairs of exhaust holes 51. The mud discharge port 2 52 can be circular, and its diameter is preferably 15-25 mm. In this way, when the inner cavity of the air stirring pipe is blocked by silt, when ventilation is performed again, since the main pipe 4 is in an inverted U-shape, the mud discharge port 1 41 is larger, and the air pressure of the compressed air is used to impact the inner cavity of the main pipe 4. At this time, the pressure of the compressed air is greater than the air pressure during normal operation, and is also greater than the water pressure at the position where the mud discharge port is located. Since the specific gravity of the silt is greater than the specific gravity of water, the silt is easily discharged from the mud discharge port 1 41 under the action of the air pressure. After the sludge is discharged, compressed air continues to be rushed into the main pipe 4. When the compressed air enters the branch pipe 5, it impacts the sludge in the branch pipe, so that the sludge in the branch pipe 5 is discharged from the mud discharge port 2 52. Of course, a small amount of sludge will also be discharged from the exhaust hole. The gas stirring pipe in the second embodiment is provided with the same mud discharge port 2 as that on the branch pipe in the first embodiment. The mud discharge principle in the second embodiment is the same as that in the branch pipe in the first embodiment. Since the water pressure below the mud discharge port is greater than the water pressure above the exhaust hole, the water pressure below the mud discharge port seals the mud discharge port and prevents the gas from being discharged downward. Therefore, during normal ventilation, the gas in the gas stirring will not be discharged from the mud discharge port, but can only be discharged upward from the exhaust hole.

[0020] By adopting the stirring method provided by the present invention, the gas discharged from the same exhaust hole on the gas stirring tube is guided in both the horizontal and vertical directions. After moving a certain distance, the gas in horizontal motion is converted into vertical motion under the action of buoyancy. Therefore, a horizontal stirring area is formed between the two vertical stirring areas finally formed, and the horizontal stirring area has the function of connecting the two vertical stirring areas. Since a plurality of exhaust holes arranged at a certain interval are provided on the gas stirring tube, a plurality of horizontal stirring areas formed by the plurality of exhaust holes stir the sludge and water horizontally, thereby eliminating the dead zone between the vertical stirring areas and fully mixing the sludge and water. At the same time, intermittent air supply is performed in the gas stirring tube, and the air intake is controlled by controlling the air intake intensity and time. Under the premise of ensuring sufficient mixing, the air consumption is reduced, thereby reducing the dissolved oxygen content in the anoxic tank.

Claims

1. A method for aeration of anoxic tanks for sewage treatment, characterized in that: The following method is adopted to make the gas discharged from the exhaust hole of the gas stirring tube flow horizontally and vertically, and a guide plate is obliquely arranged above the outlet of the exhaust hole. The gas collides with the guide plate during the rising process, and the guide plate generates a reverse force on the rising gas. Under the reverse force, the gas moves in both horizontal and vertical directions. A part of the gas moves horizontally for a distance, and another part of the gas continues to move vertically upward after bypassing the free end of the guide plate. The gas moving horizontally drives the local water flow to flow horizontally, and horizontal stirring is achieved in the local area. The gas moving horizontally will eventually move vertically upward to stir vertically, and the anoxic tank is inflated intermittently. When the sludge and water are mixed, the inflation is stopped, and the sludge and water are inflated again before they are completely separated. The intermittent inflation is repeated to keep the sludge and water in a mixed state.

2. The anoxic gas stirring method for sewage treatment according to claim 1, characterized in that: The diameter of the exhaust hole is 3-8mm, the center distance of the exhaust hole is 100-500mm, the inflation pressure is 1-2.5 times the water pressure of the water level where the exhaust hole is located, the inflation is 1-5 minutes and the interval is 15-30 minutes, and the air intake in the air stirring tube is 0.01-0.05m³ / ㎡*min.

3. The anoxic gas stirring method for sewage treatment according to claim 1, characterized in that: When it is necessary to discharge the sludge in the air stirring pipe, a mud discharge port is set below the air stirring pipe. The size of the mud discharge port is larger than the diameter of the air outlet. A pressure greater than the working air pressure is filled into the air stirring pipe to discharge the sludge from the mud discharge port below the air stirring pipe. The diameter of the mud discharge port is 15-25mm, and a plurality of mud discharge ports are arranged at intervals on the lower pipe wall of the air stirring pipe or an open mud discharge port is arranged on each section of the air stirring pipe along the length of each section of the air stirring pipe.

4. The anoxic gas stirring method for sewage treatment according to claim 1, characterized in that: The following structure is used for stirring the anoxic pool gas stirring device for sewage treatment: the anoxic pool gas stirring device for sewage treatment comprises an air stirring pipe, the air stirring pipe is a closed pipe, an exhaust hole (51) is arranged on the pipe wall of the air stirring pipe, a plurality of the exhaust holes are arranged on the pipe wall of the air stirring pipe, the exhaust hole (51) is arranged on the upper half of the air stirring pipe, when the air stirring pipe is in the working position, the opening of the exhaust hole (51) faces upward, a guide plate (6) is obliquely arranged above the opening of the exhaust hole (51), the distance between one end of the guide plate and the air stirring pipe is smaller than the distance between the other end and the air stirring pipe, the gas discharged from the exhaust hole (51) is blocked by the guide plate, and the left half of the wall is The inclination direction of the guide piece (6) corresponding to the exhaust hole (51) on the right half wall is consistent, the inclination direction of the guide piece (6) corresponding to the exhaust hole (51) on the right half wall is consistent and opposite to the inclination direction of the guide piece (6) on the left half wall, the exhaust hole (51) is arranged on the left half wall and the right half wall of the gas stirring tube along the axial direction of the gas stirring tube, the exhaust hole (51) on the left half wall and the exhaust hole (51) on the right half wall are arranged opposite to each other or staggered in sequence, when they are arranged opposite to each other, the center lines of the two exhaust holes (51) are on the same cross section of the gas stirring tube; when they are staggered, the exhaust hole (51) on the left / right half wall corresponds to the middle position of the two exhaust holes (51) on the right / left half wall.

5. The anoxic gas stirring method for sewage treatment according to claim 4, characterized in that: The included angle between the center line of the exhaust hole (51) and the vertical plane is 15°-55°, the aperture of the exhaust hole (51) is 3-8 mm, and the distance between two adjacent exhaust holes (51) along the axis of the gas stirring tube is 100-500 mm. The gas stirring tube comprises a main tube (4) and a branch tube (5), one end of the main tube (4) is closed, and the other end is connected to the gas source through the air inlet pipe (2), the branch tube (5) is arranged on the side of the main tube (4), one end is connected to the main tube (4), and the other end is closed, the exhaust hole (51) is arranged on the tube wall of the branch tube (5), and the tube center lines of each branch tube are located in the same plane.

6. The anoxic gas stirring method for sewage treatment according to claim 4, characterized in that: The gas stirring tube comprises an annular tube, the annular tube is connected to the gas source through an air inlet pipe (2), a connecting pipe is arranged in the cavity of the annular tube, and the connecting pipe is connected to the annular tube.

7. The anoxic gas stirring method for sewage treatment according to claim 5, characterized in that: The main pipe (4) is provided with a mud discharge port (41) opening downwards. The mud discharge port (41) is provided along the length direction of the main pipe (4). The opening direction of the mud discharge port is opposite to the opening direction of the exhaust hole and is larger than the opening size of the exhaust hole. The cross section of the main pipe (4) at the position where the mud discharge port (41) is provided is an inverted U-shape with an open bottom.

8. The anoxic gas stirring method for sewage treatment according to claim 5, 6 or 7, characterized in that: A second mud discharge port (52) opening downward is arranged on the lower pipe wall of the air stirring pipe corresponding to the position between two adjacent air discharge holes.

9. The anoxic gas stirring method for sewage treatment according to claim 5, 6 or 7, characterized in that: An electromagnetic valve (1) is provided at one end of the air intake pipe (2) close to the compressed air source, and the air intake pipe (2) is intermittently opened and closed by the electromagnetic valve (1). When the electromagnetic valve is opened, the sludge and water begin to mix. When the electromagnetic valve is closed, the sludge and water stop mixing and separate. When the sludge and water are completely separated or before they are completely separated, the electromagnetic valve is opened again.

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