CN219526398U - Oxidation ditch for preventing biofilm packing from losing - Google Patents

Abstract

The utility model discloses an oxidation ditch for preventing biofilm packing from losing, which relates to the technical field of sewage treatment equipment, and comprises an anaerobic tank, an anoxic tank and an aerobic tank which are sequentially communicated through a water inlet, wherein a water inlet pipe is connected to the wall of the anaerobic tank, a water outlet pipe is connected to the wall of the aerobic tank, an internal reflux structure is connected between the anaerobic tank and the aerobic tank, an aerobic Chi Nalian at the water outlet pipe is connected with a packing loss prevention structure, the packing loss prevention structure comprises a water receiving tank connected to the wall of the aerobic tank, a plurality of water outlet ports are arranged on the water receiving tank, a cylinder interception screen is connected to each water outlet port, and a flushing fluidization structure is connected under each cylinder interception screen; the water outlet pipe extends into the water receiving tank and is connected with a water receiving hopper in a threaded manner, and the top of the water receiving hopper is higher than the cylinder interception screen; the cylinder interception screen connected at the water outlet not only realizes the interception of the biomembrane filler and the effect of avoiding the loss of the biomembrane filler, but also does not influence the fluidization of the section.

Description

Oxidation ditch for preventing biofilm packing from losing

Technical Field

The utility model relates to the technical field of sewage treatment equipment, in particular to an oxidation ditch for preventing biofilm packing from losing.

Background

The oxidation ditch is a modification of an activated sludge method, an aeration tank is a closed ditch, the whole process of sewage treatment of the oxidation ditch such as water inlet, aeration, precipitation, sludge stabilization, water outlet and the like is completed in the oxidation ditch, a continuous ring type reaction tank is used as a biological reaction tank, mixed liquor is continuously circulated in the reaction tank through a closed aeration channel, the oxidation ditch is usually used under the condition of delayed aeration, and an aeration and stirring device with direction control is used for the oxidation ditch to transmit horizontal velocity to substances in the reaction tank, so that stirred liquid is circulated in the closed channel. In the standard lifting transformation process of the urban sewage treatment plant, biofilm suspended filler is added into the original aerobic tank and used as a carrier for the growth of sewage treatment microorganisms, so that the microorganism concentration of the aerobic tank is improved, and the sewage treatment capacity and pollutant reduction capacity are improved.

In the AAO type denitrification and dephosphorization process, an aerobic tank relates to water outlet, water inlet, nitrifying liquid reflux and the like, the structure of the existing oxidation ditch generally comprises an anaerobic tank, an anoxic tank and a aerobic tank, a through opening is formed in a wall body between the anaerobic tank and the anoxic tank, a through opening is formed in the wall body between the anoxic tank and the aerobic tank (in order to prevent biofilm fillers in the aerobic tank from flowing back into the anoxic tank, an interception screen is connected at the through opening generally), a water outlet is formed in an outer wall body of the aerobic tank, and a reflux pump for refluxing nitrifying liquid is connected between the aerobic tank and the anaerobic tank.

The existing oxidation ditch structure prevents biofilm fillers in the aerobic tank from returning to the anoxic tank by connecting an interception screen between the anoxic tank and the aerobic tank, but the problem that the biofilm fillers in the aerobic tank are easy to run away from a water outlet exists, and a reflux pump connected between the aerobic tank and the anaerobic tank can damage the biofilm fillers in the running process, so that the biofilm fillers in the aerobic tank run away.

Disclosure of Invention

The utility model aims to solve the technical problem that biofilm packing in an aerobic tank of an oxidation ditch is easy to run off, and aims to provide the oxidation ditch for preventing the biofilm packing from running off and solve the problem that the biofilm packing in the aerobic tank of the oxidation ditch is easy to run off.

The utility model is realized by the following technical scheme:

an oxidation ditch for preventing biofilm packing from losing comprises an anaerobic tank, an anoxic tank and an aerobic tank which are sequentially communicated through a water inlet, wherein a water inlet pipe is connected to the wall of the anaerobic tank, a water outlet pipe is connected to the wall of the aerobic tank, an internal reflux structure is connected between the anaerobic tank and the aerobic tank, an aerobic Chi Nalian at the water outlet pipe is connected with a packing loss prevention structure, the packing loss prevention structure comprises a water receiving tank connected to the wall of the aerobic tank, a plurality of water outlet ports are arranged on the water receiving tank, each water outlet port is connected with a cylinder interception screen, and a flushing fluidization structure is connected under each cylinder interception screen; the water outlet pipe extends into the water receiving tank and is connected with a water receiving hopper in a threaded manner, and the top of the water receiving hopper is higher than the cylinder interception screen.

The cylindrical interception screen connected at the water outlet is submerged to a certain depth in the running process, and the biofilm fillers can pass through the upper part and the lower part of the cylindrical screen, so that the interception of the biofilm fillers is realized, the loss of the biofilm fillers is avoided, and the section fluidization is not influenced.

The water receiving hopper is arranged on the water outlet pipe in the water receiving tank, the top of the water receiving hopper is higher than the cylindrical screen, the liquid level in the aerobic tank can be controlled through the water receiving hopper, the cylindrical interception screen is submerged, the interception effect of the cylindrical interception screen on the biofilm filler is achieved, and meanwhile, when the cylindrical interception screen needs to be overhauled, the water receiving hopper is detached from the water outlet pipe, so that the cylindrical interception screen is exposed out of the water surface, and overhauling and maintenance are facilitated.

Further, the water inlet end of the water inlet pipe penetrates through the anoxic tank and the aerobic tank to extend to the outside of the wall body of the aerobic tank.

Further, the flushing fluidization structure comprises a horizontal perforated pipe connected right below the cylinder interception screen, and the direction of the perforation is vertically downward.

Further, the internal reflux structure comprises a submersible through-wall pump.

The horizontal perforated pipe can be a stainless steel perforated pipe, the pipe diameter can be DN50, the aperture can be 4-6mm, the hole spacing is 100-200mm, and the airflow orifice flow velocity is 15-20m/s; the horizontal perforated pipe is 200-300mm away from the bottom of the cylinder interception screen. The above technical parameters are adjusted by the skilled person according to the actual situation.

The cylinder interception screen can be made of stainless steel, the thickness is 3-5mm, the aperture is 18-20mm, the aperture ratio is 40-50%, the diameter is 400-800 mm, the clearance between the cylinder interception screens is 800-1000mm, the distance between the cylinder interception screens and the running water surface is 400-600mm, and the flow rate of the cylinder interception screen through holes is 0.04-0.08m/s. The above technical parameters are adjusted by the skilled person according to the actual situation.

Through connect the horizontal perforation pipe as washing vulcanization structure under drum interception screen cloth, through to the intraductal aeration of horizontal perforation, can make drum interception screen cloth keep clean, fibre impurity can't adhere to on drum interception screen cloth, make drum interception screen cloth overflow unobstructed more, ensure that the liquid level difference of drum interception screen cloth both sides maintains in normal range.

Further, an internal reflux interception screen with the same height as the wall body of the aerobic tank is connected to the internal reflux structure of the aerobic tank, a cavity is formed by the internal reflux interception screen and the wall body of the aerobic tank, and the internal reflux structure is positioned in the cavity; the inner reflux interception screen is fixed with the aerobic tank wall body through a support frame; and the outer side of the inner reflux interception screen is connected with a screen flushing structure.

The internal reflux interception screen can be made of stainless steel, the thickness is 3-5mm, the aperture is 18-20mm, and the aperture ratio is 40-50%. The above technical parameters are adjusted by the skilled person according to the actual situation.

When nitrifying liquid in the aerobic tank is refluxed by the internal reflux structure, biofilm packing in the nitrifying liquid is isolated outside the cavity through the reflux interception screen, so that the biofilm packing is prevented from being pumped away by the submersible wall penetrating pump, and further the loss of the biofilm packing in the aerobic tank is prevented.

Further, the screen flushing structure comprises annular perforated pipes connected to the outer sides of the inner reflux interception screens, and the annular perforated pipes are provided with holes obliquely downwards at two sides in a staggered manner; the bottom of the aerobic tank is connected with a bracket, and the annular perforated pipe is arranged on the bracket.

The annular perforated pipe can be made of stainless steel, the pipe diameter is DN50, the opening angle is 30-50 degrees, the aperture size is 4-6mm, the opening interval is 100-200mm, and the airflow orifice flow velocity is 15-20m/s; the annular perforated pipe is 400-600mm away from the pool floor of the aerobic pool and 100-200mm away from the inner reflux interception screen. The above technical parameters can be adjusted by those skilled in the art according to practical situations.

Further, the cross-sectional shape of the inner reflux arresting screen includes a trapezoid structure.

Through connecting annular perforated pipe in the interior backward flow interception screen cloth outside to the aeration in the annular perforated pipe, can wash interior backward flow interception screen cloth to carry out fluidization friction to the biofilm packing near the interior backward flow interception screen cloth, make interior backward flow interception screen cloth keep clean, the fibrous impurity can't adhere to, and interior backward flow screen cloth is crossed water more smoothly, ensures that the liquid level difference of interior backward flow screen cloth both sides maintains in normal range.

Further, a duckbill valve is connected to a water inlet on the wall body of the anoxic tank, and the duckbill valve is positioned in the aerobic tank.

The duckbill valve is formed by special processing of elastic chloroprene rubber and artificial fiber, and has a shape similar to a duckbill, so the duckbill valve is called. Under the condition of no internal pressure, the duckbill outlet is folded under the self elastic action, and gradually increases along with the gradual increase of the internal pressure, so that the liquid can be discharged at a high flow rate.

Through connecting the duckbill valve in the water inlet department of oxygen deficiency pond wall body, the structure of duckbill valve makes the biofilm packing in the good oxygen pond unable entering into the oxygen deficiency pond through the water inlet on the oxygen deficiency pond in, has further avoided the biofilm packing in the good oxygen pond to run off, also need not to install the screen cloth after connecting the duckbill valve simultaneously, has avoided fibrous impurity to stop up the condition that the screen cloth caused the difficulty of intaking, has also reduced investment cost simultaneously.

Further, the anaerobic tank, the anoxic tank and the aerobic tank are provided with a flow pushing device.

Through installing the impeller in anaerobic tank, anoxic tank and good oxygen pond, can accelerate the velocity of flow of the interior water of anaerobic tank and anoxic tank, the impeller in the aerobic tank can make the biofilm packing circulate in good oxygen pond except can accelerate the velocity of flow of water, form complete mixed flow state, improve the fluidization homogeneity of biofilm packing, avoid biofilm packing to pile up in drum interception screen cloth and interior backward flow interception screen cloth department, make it produce friction with drum interception screen cloth and interior backward flow interception screen cloth simultaneously, be favorable to drum interception screen cloth and interior backward flow interception screen cloth to keep clean and clear water.

Further, the aerobic Chi Nalian is connected with a plurality of microporous aeration plates.

The microporous aeration disc connected in the aerobic tank acts together with the impeller to further improve the fluidity of the biofilm packing in the aerobic tank.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

(1) The cylindrical interception screen connected at the water outlet is submerged to a certain depth in the running process, and the biofilm fillers can pass through the upper part and the lower part of the cylindrical screen, so that the interception of the biofilm fillers is realized, the loss of the biofilm fillers is avoided, and the section fluidization is not influenced. The water receiving hopper is arranged on the water outlet pipe in the water receiving tank, the top of the water receiving hopper is higher than the cylindrical screen, the liquid level in the aerobic tank can be controlled through the water receiving hopper, the cylindrical interception screen is submerged, the interception effect of the cylindrical interception screen on the biofilm filler is achieved, and meanwhile, when the cylindrical interception screen needs to be overhauled, the water receiving hopper is detached from the water outlet pipe, so that the cylindrical interception screen is exposed out of the water surface, and overhauling and maintenance are facilitated.

(2) Through connect the horizontal perforation pipe as washing vulcanization structure under drum interception screen cloth, through to the intraductal aeration of horizontal perforation, can make drum interception screen cloth keep clean, fibre impurity can't adhere to on drum interception screen cloth, make drum interception screen cloth overflow unobstructed more, ensure that the liquid level difference of drum interception screen cloth both sides maintains in normal range.

(3) When nitrifying liquid in the aerobic tank is refluxed by the internal reflux structure, biofilm packing in the nitrifying liquid is isolated outside the cavity through the reflux interception screen, so that the biofilm packing is prevented from being pumped away by the submersible wall penetrating pump, and further the loss of the biofilm packing in the aerobic tank is prevented.

(4) Through connecting annular perforated pipe in the interior backward flow interception screen cloth outside to the aeration in the annular perforated pipe, can wash interior backward flow interception screen cloth to carry out fluidization friction to the biofilm packing near the interior backward flow interception screen cloth, make interior backward flow interception screen cloth keep clean, the fibrous impurity can't adhere to, and interior backward flow screen cloth is crossed water more smoothly, ensures that the liquid level difference of interior backward flow screen cloth both sides maintains in normal range.

(5) Through connecting the duckbill valve in the water inlet department of oxygen deficiency pond wall body, the structure of duckbill valve makes the biofilm packing in the good oxygen pond unable entering into the oxygen deficiency pond through the water inlet on the oxygen deficiency pond in, has further avoided the biofilm packing in the good oxygen pond to run off, also need not to install the screen cloth after connecting the duckbill valve simultaneously, has avoided fibrous impurity to stop up the condition that the screen cloth caused the difficulty of intaking, has also reduced investment cost simultaneously.

(6) Through installing the impeller in anaerobic tank, anoxic tank and good oxygen pond, can accelerate the velocity of flow of the interior water of anaerobic tank and anoxic tank, the impeller in the aerobic tank can make the biofilm packing circulate in good oxygen pond except can accelerate the velocity of flow of water, form complete mixed flow state, improve the fluidization homogeneity of biofilm packing, avoid biofilm packing to pile up in drum interception screen cloth and interior backward flow interception screen cloth department, make it produce friction with drum interception screen cloth and interior backward flow interception screen cloth simultaneously, be favorable to drum interception screen cloth and interior backward flow interception screen cloth to keep clean and clear water.

(7) The microporous aeration disc connected in the aerobic tank acts together with the impeller to further improve the fluidity of the biofilm packing in the aerobic tank.

Drawings

The accompanying drawings, which are included to provide a further understanding of embodiments of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the principles of the utility model. In the drawings:

FIG. 1 is a top view of an oxidation ditch for preventing biofilm pack loss according to example 1 of the present utility model;

FIG. 2 is a cross-sectional view taken along the direction A-A in FIG. 1;

FIG. 3 is a top view of an oxidation ditch for preventing biofilm packing loss in accordance with example 2 of the present utility model;

FIG. 4 is a cross-sectional view taken along the direction B-B in FIG. 3;

FIG. 5 is a top view of an oxidation ditch for preventing biofilm pack loss according to example 3 of the present utility model;

FIG. 6 is a top view of an oxidation ditch for preventing biofilm packing loss in accordance with example 4 of the present utility model;

FIG. 7 is a top view of an oxidation ditch for preventing biofilm packing loss in accordance with example 5 of the present utility model.

In the drawings, the reference numerals and corresponding part names:

11-an anaerobic tank, 12-an anoxic tank, 13-an aerobic tank, 14-a water inlet, 15-a submersible wall-penetrating pump, 16-a water inlet pipe, 17-a cylinder interception screen, 18-a water receiving tank, 19-a water receiving hopper, 21-a water outlet pipe, 22-water outlet, 23-horizontal perforated pipe, 24-annular perforated pipe, 25-internal reflux interception screen, 26-support frame, 27-duckbill valve, 28-impeller and 29-microporous aeration disk.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the utility model, as presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the present utility model, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, connected or integrally connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

Example 1

The embodiment provides an oxidation ditch for preventing biofilm packing from losing, as shown in fig. 1 and 2, the oxidation ditch comprises an anaerobic tank 11, an anoxic tank 12 and an aerobic tank 13 which are sequentially communicated through a water inlet 14, wherein a water inlet pipe 16 is connected to the wall of the anaerobic tank 11, a water outlet pipe 21 is connected to the wall of the aerobic tank 13, a diving through-wall pump 15 is connected between the anaerobic tank 11 and the aerobic tank 13, a packing loss prevention structure is connected to the aerobic tank 13 at the water outlet pipe 21, the packing loss prevention structure comprises a water receiving tank 18 connected to the wall of the aerobic tank 13, four water outlet ports 22 are arranged on the water receiving tank 18, a cylinder interception screen 17 is connected to each water outlet port 22, a horizontal perforating pipe 23 is connected to the right lower part of each cylinder interception screen 17, and the perforating direction is vertically downward; the water outlet pipe 21 extends into the water receiving tank 18 and is connected with a water receiving hopper 19 in a threaded manner, and the top of the water receiving hopper 19 is higher than the cylinder interception screen 17.

Wherein the water inlet end of the water inlet pipe 16 passes through the anoxic tank 12 and the aerobic tank 13 to extend to the outside of the wall body of the aerobic tank 13.

When the oxidation ditch of the embodiment is used, sewage enters the anaerobic tank 11 from the water inlet pipe 16, sewage treated in the anaerobic tank 11 enters the anoxic tank 12, sewage treated in the anoxic tank 12 enters the aerobic tank, and before being discharged out of the aerobic tank 13, the sewage treated in the aerobic tank firstly enters the cylinder interception screen 17, and interception of biofilm fillers mixed in water is realized through the cylinder interception screen 17, so that the biofilm fillers are prevented from being discharged from the water outlet 22 together with water, and loss of the biofilm fillers is avoided.

The water after passing through the cylindrical screen enters the water receiving tank 18, the treated water is discharged into the water outlet pipe 21 through the water receiving hopper 19 arranged in the water receiving tank 18, then is discharged out of the aerobic tank 13, and enters the next treatment process, and the arranged water receiving hopper 19 is higher than the cylindrical screen, so that the cylindrical screen can be always submerged in the operation process.

Example 2

Referring to fig. 3 and 4, according to example 1, an oxidation ditch for preventing biofilm packing loss is provided, except for all the technical features in example 1, an internal reflux interception screen 25 with the same height as the wall of the aerobic tank 13 is connected to the submerged wall penetrating pump 15 of the aerobic tank 13, the internal reflux interception screen 25 and the wall of the aerobic tank 13 form a cavity, and the submerged wall penetrating pump 15 is positioned in the cavity; the inner reflux interception screen 25 is fixed with the wall of the aerobic tank 13 through a support frame 26; the outer side of the inner reflux interception screen 25 is connected with an annular perforated pipe 24, and holes are formed in the two sides of the annular perforated pipe 24 obliquely downwards in a staggered manner; the bottom of the aerobic tank 13 is connected with a bracket, and an annular perforated pipe 24 is arranged on the bracket.

Wherein the cross-section of the inner reflux intercepting screen 25 has a trapezoidal shape.

Unlike embodiment 1, this embodiment installs internal reflux interception screen 25 at the submerged wall penetrating pump 15 of the aerobic tank 13, and when the submerged wall penetrating pump 15 is refluxing the nitrified liquid in the aerobic tank 13 to the anoxic tank 12, the biofilm packing is intercepted outside the wall body by the reflux interception screen, thereby avoiding damage to the biofilm packing caused by the submerged wall penetrating pump 15 in the operation process, and further reducing the loss of the biofilm packing.

Example 3

Based on example 2, referring to fig. 5, this example provides an oxidation ditch for preventing biofilm packing loss, and apart from all the technical features of example 2, a duckbill valve 27 is connected to the water inlet 14 on the wall of the anoxic tank 12, and the duckbill valve 27 is located in the aerobic tank 13.

Unlike example 2, this example has a duckbill valve 27 connected to the water inlet 14 on the wall of the anoxic tank 12, and the water entering the aerobic tank 13 from the anoxic tank 12 is discharged through the duckbill valve 27, and the duckbill valve 27 has a structure that the biofilm-packing in the aerobic tank 13 cannot enter the anoxic tank 12 through the water inlet 14 on the anoxic tank 12, and cannot automatically flow back, thereby further avoiding the loss of the biofilm-packing in the aerobic tank 13.

Example 4

Based on example 3, referring to fig. 6, this example provides an oxidation ditch for preventing biofilm packing loss, and in addition to all the technical features of example 3, a pusher 28 is installed in each of the anaerobic tank 11, the anoxic tank 12 and the aerobic tank 13.

Unlike example 3, the embodiment has the flow impeller 28 installed in the anaerobic tank 11, the anoxic tank 12 and the aerobic tank 13, which can accelerate the flow rate of the water body and improve the treatment efficiency, and the flow impeller 28 in the aerobic tank can also circulate the biofilm pack in the aerobic tank 13 to form a completely mixed flow state, thereby improving the fluidization uniformity of the biofilm pack, avoiding the biofilm pack from accumulating at the cylinder interception screen 17 and the inner reflux interception screen 25, and simultaneously making the biofilm pack rub against the cylinder interception screen 17 and the inner reflux interception screen 25, thereby being beneficial to keeping the cylinder interception screen 17 and the inner reflux interception screen 25 clean and smooth in water.

Example 5

Based on example 4, referring to fig. 7, this example provides an oxidation ditch for preventing biofilm packing loss, and five microporous aeration panels 29 are connected to the aerobic tank 13, except for all the technical features of example 4.

Unlike example 4, this example has a microporous aeration disc 29 connected to the aerobic tank 13, and a microporous aeration disc connected to the aerobic tank 13, and works together with a flow impeller 28 to further improve the fluidity of the biofilm carriers in the aerobic tank 13.

The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the utility model, and is not meant to limit the scope of the utility model, but to limit the utility model to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the utility model are intended to be included within the scope of the utility model.

Claims (10)

1. The utility model provides an oxidation ditch for preventing biofilm packing loss, includes anaerobic tank (11), anoxic tank (12) and aerobic tank (13) that communicate in proper order through water inlet (14), be connected with inlet tube (16) on the wall body of anaerobic tank (11), be connected with outlet pipe (21) on the wall body of aerobic tank (13), be connected with internal reflux structure between anaerobic tank (11) and the aerobic tank (13), characterized in that, be connected with the packing in the aerobic tank (13) of outlet pipe (21) department and prevent loss structure, packing prevents loss structure including connecting water receiving tank (18) on the wall body of aerobic tank (13), be provided with a plurality of outlet ports (22) on water receiving tank (18), every outlet port (22) department all is connected with drum interception screen cloth (17), every drum interception screen cloth (17) all is connected with the fluidization structure that washes under; the water outlet pipe (21) extends into the water receiving tank (18) and is connected with a water receiving hopper (19) in a threaded mode, and the top of the water receiving hopper (19) is higher than the cylinder interception screen (17).

2. An oxidation ditch for preventing biofilm pack loss according to claim 1, wherein the water inlet end of the water inlet pipe (16) extends to the outside of the wall of the aerobic tank (13) through the anoxic tank (12) and the aerobic tank (13).

3. An oxidation ditch for preventing biofilm pack loss according to claim 1, wherein the flushing fluidization structure comprises a horizontal perforated pipe (23) connected directly below the cylinder interception screen (17) with the direction of the perforation being vertically downward.

4. An oxidation ditch for preventing biofilm pack loss according to claim 1, wherein the internal return structure comprises a submersible through-wall pump (15).

5. An oxidation ditch for preventing biofilm pack loss according to claim 1, wherein an inner reflux structure of the aerobic tank (13) is connected with an inner reflux interception screen (25) with the same height as the wall of the aerobic tank (13), the inner reflux interception screen (25) and the wall of the aerobic tank (13) form a cavity, and the inner reflux structure is positioned in the cavity; the inner reflux interception screen (25) is fixed with the wall of the aerobic tank (13) through a supporting frame (26); and a screen flushing structure is connected to the outer side of the inner reflux interception screen (25).

6. An oxidation ditch for preventing biofilm pack loss according to claim 5, wherein said screen flushing structure comprises an annular perforated tube (24) connected to the outside of said inner reflux interception screen (25), said annular perforated tube (24) being perforated diagonally downwards and bilaterally staggered; the bottom of the aerobic tank (13) is connected with a bracket, and the annular perforated pipe (24) is arranged on the bracket.

7. An oxidation ditch for preventing biofilm pack loss according to claim 5, wherein the cross-sectional shape of the inner reflux interception screen (25) comprises a trapezoid structure.

8. An oxidation ditch for preventing biofilm pack loss according to claim 1, wherein a duckbill valve (27) is connected to a water inlet (14) on the wall of the anoxic tank (12), and the duckbill valve (27) is positioned in the aerobic tank (13).

9. An oxidation ditch for preventing biofilm pack loss according to claim 1, wherein a pusher (28) is arranged in each of the anaerobic tank (11), the anoxic tank (12) and the aerobic tank (13).

10. An oxidation ditch for preventing biofilm pack loss according to claim 1, wherein a plurality of microporous aeration discs (29) are connected in the aerobic tank (13).