A sewage treatment device and a method for treating food processing wastewater

Abstract

The application discloses a sewage treatment device and a food processing wastewater treatment method. The sewage treatment device comprises an anaerobic zone, an anoxic zone and an aerobic zone. The aerobic zone is provided with a first intercepting net. The first intercepting net is arranged around a water outlet pipe of the aerobic zone. The aerobic zone is provided with a reflux tank. The reflux tank is connected with the aerobic zone through a lifting device. The reflux tank and the water outlet pipe are arranged on two sides of the first intercepting net. A second intercepting net, a first connecting pipe and a second connecting pipe are arranged on a side wall of the reflux tank. The second intercepting net is arranged at the first connecting pipe. The height of the second connecting pipe is higher than that of the first connecting pipe. The reflux tank is connected with the anoxic zone through the first connecting pipe. The reflux tank is connected with the anaerobic zone through the second connecting pipe. The anaerobic zone is provided with a carrier. Stirring devices are arranged in the anaerobic zone, the anoxic zone and the reflux tank. The sewage treatment device solves the technical problem of carrier accumulation at the end in the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of food processing wastewater treatment, and in particular relates to a sewage treatment device and a food processing wastewater treatment method. Background Art

[0002] The food industry is extremely complex, encompassing production processes such as sugar refining, brewing, meat processing, and dairy processing. All wastewater produced contains organic matter, is highly oxygen-consuming, and contains large amounts of suspended solids. Wastewater from animal-based food processing also contains animal excrement, blood, fur, grease, and potentially pathogens. Consequently, it consumes a high amount of oxygen and is significantly more polluting than wastewater from plant-based food processing.

[0003] Existing treatment processes typically utilize pretreatment followed by enhanced biochemical treatment to remove pollutants from wastewater. Enhanced biochemical processes typically include anaerobic, anoxic, aerobic, and sedimentation processes. In practice, the impact of influent pollutants can easily kill microorganisms within the system, leading to large amounts of sludge overflowing the sedimentation tank and resulting in substandard wastewater treatment.

[0004] Currently, carriers are used to treat food processing wastewater, but they typically involve adding interception nets at the end of the treatment process and only in aerobic tanks. Adding carriers to anaerobic and anoxic tanks can cause clogging of the interception nets within these tanks. When this occurs, adding aeration and cleaning disrupts the oxygen-free environment of these tanks, compromising tank functionality. Summary of the Invention

[0005] In response to the current technical problems, the present invention aims to provide a sewage treatment device and a method for treating food processing wastewater. The sewage treatment device can solve the technical problem of carrier accumulation at the end in the prior art.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A sewage treatment device comprises an anaerobic zone, an anoxic zone and an aerobic zone, wherein a first interception net is provided in the aerobic zone and is arranged around the outlet pipe of the aerobic zone; its structural features are as follows: a reflow trough is provided in the aerobic zone, the reflow trough is connected to the aerobic zone via a lifting device, and the reflow trough and the outlet pipe of the aerobic zone are respectively arranged on both sides of the first interception net; a second interception net, a first connecting pipe and a second connecting pipe are provided on the side wall of the reflow trough, the second interception net is arranged at the first connecting pipe, and the height of the second connecting pipe is higher than that of the first connecting pipe; the reflow trough is connected to the anoxic zone via the first connecting pipe, and the reflow trough is connected to the anaerobic zone via the second connecting pipe; a carrier is provided in the anaerobic zone, and a stirring device is provided in the anaerobic zone, the anoxic zone and the reflow trough.

[0008] When the sewage treatment device of the present invention is used, the sewage first enters the anaerobic zone. After being treated by the microorganisms on the carrier in the anaerobic zone, the carrier enters the anoxic zone along with the sewage for denitrification treatment. The sewage and the carrier then flow into the aerobic zone for treatment, and the carrier is intercepted by the first interception net and discharged from the outlet pipe. The sewage is purified during the flow process. Part of the sewage and the carrier in the aerobic zone are lifted into the reflow tank by the action of the lifting device. By arranging a stirring device in the reflow tank, the carrier in the reflow tank is treated and flowed. Due to the interception effect of the second interception net on the carrier, the sewage in the reflow tank flows back to the anoxic zone through the first connecting pipe to ensure denitrification reaction, and the carrier returns to the anaerobic zone through the second connecting pipe, thereby solving the technical problem of carrier accumulation at the end and ensuring the circulation of the carrier.

[0009] Preferably, the lifting device includes an inverted U-shaped lifting pipe, a motor, a rotating shaft mounted on the power output end of the motor, and a spiral blade disposed on the rotating shaft, wherein the spiral blade extends along the length of the rotating shaft; one end of the lifting pipe faces the reflow trough, and the other end faces the aerobic zone; the rotating shaft is disposed in the lifting pipe, and the lifting end of the rotating shaft is disposed in the aerobic zone, with a gap provided between the spiral blade and the inner wall of the lifting pipe. Driven by the motor, the rotating shaft drives the spiral blade to rotate, while simultaneously lifting the carrier and sewage at the mouth of the lifting pipe in the aerobic zone upward into the reflow trough. By adjusting the motor speed, the rotation speed of the rotating shaft can be changed. When the speed is slow, the carrier can be lifted into the reflow trough, while the sewage flows out through the gap between the spiral blade and the inner wall of the lifting pipe; when the speed is fast, the carrier and sewage can be lifted into the reflow trough together.

[0010] Preferably, an air brush device is provided below the end of the riser tube facing the aerobic zone. One end of the air brush device is connected to the first blower, and the other end faces the end of the riser tube. The air brush device can transfer gas from the first blower into the riser tube. When a blockage occurs in the riser tube, the first blower is turned on to inflate the air brush device. The gas is then transferred to the riser tube via the air brush device. As the gas rises, it impacts the blocked area in the riser tube, thereby clearing the blockage.

[0011] Preferably, the air brush device includes a vertically arranged gas collecting cylinder with an opening at the top; the bottom of the gas collecting cylinder is connected to the first blower via an air inlet pipe, and a rotatably connected cover plate is provided on the top of the gas collecting cylinder, the cover plate is provided with a plurality of through holes, and at least one elastic element is provided between the cover plate and the top of the gas collecting cylinder. The elastic element can be a spring. When the sewage treatment device is operating normally, a small amount of gas is blown into the gas collecting cylinder by the first blower, and the gas flows upward into the lifting pipe through the through holes in the cover plate, which can assist the spiral blades in lifting the carrier; and when the lifting device needs to increase the lifting amount or the lifting pipe is blocked, the air supply can be increased. When the gas pressure in the gas collecting cylinder reaches a certain level, the cover plate will be opened outward, and the gas will instantly rush out and enter the lifting pipe, vigorously flushing the lifting pipe.

[0012] Preferably, a first liquid level gauge is provided in the anaerobic zone, and a second liquid level gauge is provided in the aerobic zone, the second liquid level gauge being located at the outlet pipe. By providing the first and second liquid level gauges, the liquid level difference between the anaerobic and aerobic zones can be monitored. If the liquid level difference increases, it indicates that the first interception net is clogged with carriers, and the lifting capacity of the lifting device can be increased to increase the amount of carriers to be recovered.

[0013] Preferably, the first connecting pipe is provided with a first valve, the second connecting pipe is provided with a second valve, and the stirring device, first liquid level gauge, second liquid level gauge, lifting device, first valve, second valve, and aeration device in the aerobic zone are all electrically connected to a control system. By configuring the control system, the stirring device frequency, the opening of the first and second valves, the air supply volume of the aeration device, the lifting volume of the lifting device, etc. are controlled based on instruments such as liquid level gauges. Any related problems can be automatically resolved without manual operation, ensuring system stability and timely resolution.

[0014] Preferably, the cross section of the aerobic zone is rectangular, and the ratio of the width to the length of the rectangle is greater than or equal to 1: 5. By setting the width-to-length ratio of the aerobic zone, the water flow rate in the aerobic zone can be reduced, preventing the carriers from flowing too fast with the water and accumulating at the end.

[0015] Specifically, the reflow trough is arranged on the side wall of the aerobic zone, and the side of the reflow trough provided with the first connecting pipe is adjacent to the anoxic zone, and the side of the reflow trough provided with the second connecting pipe is adjacent to the anaerobic zone.

[0016] Based on the same inventive concept, the present application also provides a method for treating food processing wastewater, which is treated using the sewage treatment device described above and specifically comprises the following steps:

[0017] S1. After the wastewater enters the anaerobic zone for treatment, the wastewater carries the carrier into the anoxic zone for denitrification treatment;

[0018] S2, the wastewater and carrier then enter the aerobic zone, and the wastewater treated in the aerobic zone is discharged through the outlet pipe;

[0019] S3. Part of the wastewater and carrier in the aerobic tank is lifted into the reflow tank through the lifting device. The wastewater in the reflow tank is returned to the anoxic zone through the first connecting pipe, and the carrier in the reflow tank is returned to the anaerobic zone through the second connecting pipe.

[0020] Food processing wastewater is characterized by high pollutant concentrations and complex composition. The wastewater first enters an anaerobic tank, where a carrier adsorbs insoluble impurities. Some particulate impurities adhere to the carrier surface, performing the initial pollutant removal process. Because the carrier is in an anaerobic environment, microorganisms on the carrier decompose soluble organic matter. The anaerobic bacteria on the carrier convert large soluble organic molecules into small organic molecules, which are more easily absorbed and utilized in subsequent reactions. The carrier then enters an anoxic tank along with the wastewater. Denitrifying bacteria attached to the carrier, using both soluble and insoluble organic matter as a carbon source, convert the large amounts of nitrate in the anoxic tank into nitrogen gas, which is released into the air, achieving denitrification. The wastewater and carrier then flow into an aerobic tank, where aerobic bacteria on the carrier begin decomposing ammonia nitrogen and the remaining soluble and insoluble organic matter. In addition, common carrier materials are cylindrical structures made of polymer materials such as PE or PP, with a diameter of 10 to 30 cm, a porous interior, a large specific surface area, a hard texture, and are not easy to decompose. Their service life is generally maintained at more than 20 years. Therefore, the microorganisms on the carrier will not be easily discharged. The microbial era cycle is long, and more protozoa and metazoa will appear. Protozoa, metazoa, and bacteria form a complete biological chain system, that is, protozoa feed on bacteria and organic matter, and metazoa feed on protozoa and organic matter. The phosphorus element in the wastewater will be enriched in the metazoan body during this process. When the metazoan finally dies, it falls off from the carrier to form insoluble sludge, which is regularly discharged. The method of the present invention is different from the anaerobic phosphorus release and aerobic phosphorus absorption of the conventional A2O activated sludge method, and the principle of sludge removal is different. The phosphorus removal method of the present invention utilizes the biological chain to remove phosphorus, with a smaller amount of sludge discharged, a lower sludge disposal fee, and a more obvious effect. The food processing wastewater treatment method of the present invention utilizes the continuous circulation of the carrier in the anaerobic tank, the anoxic tank and the aerobic tank, thereby completely removing pollutants such as organic matter, nitrogen and phosphorus.

[0021] Preferably, the dissolved oxygen in the aerobic zone is 1-4 mg / L, the air-water volume ratio is 5-15:1; the density of the carrier is 1-1.01 g / cm 3 , the carrier filling rate is 10 to 40%.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The sewage treatment device of the present invention solves the accumulation of terminal carriers by setting a return trough, a lifting device and a second interception net. At the same time, it separates sewage from the carriers, ensures that sewage returns to the anoxic tank and the carriers return to the aerobic tank, and allows the carriers to circulate during the treatment process.

[0024] 2. The sewage treatment device of the present invention assists the fluidity of the carrier in the lifting device by providing an air brush device, and can also play an air brush cleaning role on the lifting device.

[0025] 3. The sewage treatment device of the present invention is equipped with a control system, which eliminates the need for human control and ensures stable and safe operation of the device.

[0026] 4. The food processing wastewater treatment method of the present invention increases the amount and activity of all organisms in the wastewater by allowing the carrier to flow in the process flow, thereby improving the impact resistance of food wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the sewage treatment device of the present invention;

[0028] Figure 2 yes Figure 1 Schematic diagram of the middle reflux tank structure;

[0029] Figure 3 yes Figure 2 Schematic diagram of the structure of the middle lifting device;

[0030] Figure 4 yes Figure 2 Schematic diagram of the air brush device structure.

[0031] In the figure

[0032] 1-tank body, 2-water inlet pipe, 3-first flow hole, 4-control system, 5-first liquid level gauge, 6-stirring device, 7-second valve, 8-first valve, 9-second interception net, 10-lifting device, 10-1-lifting pipe, 10-2-motor, 10-3-rotating shaft, 10-4-spiral blade, 11-second liquid level gauge, 12-first interception net, 13-water outlet pipe, 14-aeration device, 14-1-aeration plate, 14-2-second blower, 15-carrier, 16-first partition, 17-anaerobic zone, 18-anoxic zone, 19-aerobic zone, 20-reflow trough, 21-air brush device, 21-1 gas collecting cylinder, 21-2-air inlet pipe, 21-3-cover plate, 21-4-through hole, 21-5-elastic element, 22-second flow hole, 23-first connecting pipe, 24-second connecting pipe, 25-second partition, 26-first blower. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments may be combined unless they conflict. For ease of description, the words "upper," "lower," "left," and "right" appear below merely to indicate the directions of upper, lower, left, and right in the accompanying drawings and do not limit the structure.

[0034] like Figure 1 As shown, a sewage treatment device of this embodiment includes a tank body 1 and a control system 4. The ratio of the width to the length of the tank body 1 is 1:5. A first partition 16 is provided along the length of the tank body 1. The first partition 16 and the right side wall of the tank body 1 enclose an aerobic zone 19. A second partition 25 is provided along the width of the area enclosed by the first partition 16 and the left side wall of the tank body 1, thereby dividing the left side of the tank body 1 into an anaerobic zone 17 and an anoxic zone 18. The second partition 25 is provided with a first flow hole 3, and the anaerobic zone 17 and the anoxic zone 18 are connected through the first flow hole 3. The first partition 16 is provided with a second flow hole 22, and the anoxic zone 18 and the aerobic zone 19 are connected through the second flow hole 22. The first flow hole 3 and the second flow hole 22 are respectively arranged at opposite corners of the anoxic zone 18. The side wall of the anaerobic zone 17 is provided with an inlet pipe 2, and the side wall of the aerobic zone 19 is provided with an outlet pipe 13. A first liquid level gauge 5 is provided in the anaerobic zone 17, and a second liquid level gauge 11 is provided in the aerobic zone 19. The second liquid level gauge 11 is provided at the outlet pipe 13. A first interception net 12 is provided in the aerobic zone 19 along the width direction. The first interception net 12 is provided close to the outlet pipe 13. An aeration device 14 and a reflow trough 20 are provided in the aerobic zone 19. The reflow trough 20 is provided on the inner side wall of the aerobic zone 19. The reflow trough 20 is connected to the aerobic zone 19 through a lifting device 10, and the reflow trough 20 and the outlet pipe 13 are respectively provided on both sides of the first interception net 12. The aeration device 14 includes an aeration disk 14-1 provided in the aerobic zone 19 and a second blower 14-2 connected to the aeration disk 14-1. A carrier 15 is provided in the anaerobic zone 17, and a stirring device 6 is provided in the anaerobic zone 17, the anoxic zone 18 and the reflow trough 20. Carrier 15 is a cylindrical structure made of a polymer material such as PE or PP, with a diameter of 10 to 30 cm. Carrier 15 is porous, has a large specific surface area, and is hard and resistant to decomposition, resulting in a long service life, typically exceeding 20 years. The stirring device 6 used in anaerobic zone 17 and anoxic zone 18 has a stirring power of at least 5W per cubic meter, but no more than 15W.

[0035] like Figure 1 and Figure 2As shown, a second intercepting net 9, a first connecting pipe 23 and a second connecting pipe 24 are provided on the side wall of the reflow trough 20. The second intercepting net 9 is provided at the first connecting pipe 23, and the height of the second connecting pipe 24 is higher than that of the first connecting pipe 23. One side of the reflow trough 20 on which the first connecting pipe 23 is provided is adjacent to the anoxic zone 18, and the reflow trough 20 and the anoxic zone 18 are communicated through the first connecting pipe 23, and a first valve 8 is provided on the first connecting pipe 23. One side of the reflow trough 20 on which the second connecting pipe 24 is provided is adjacent to the anaerobic zone 17, and the reflow trough 20 and the anaerobic zone 17 are communicated through the second connecting pipe 24, and a second valve 7 is provided on the second connecting pipe 24. As shown Figure 2 and Figure 3 As shown, the lifting device 10 includes an inverted U-shaped lifting pipe 10-1, a motor 10-2, a rotating shaft 10-3 mounted on the power output end of the motor 10-2, and a spiral blade 10-4 provided on the rotating shaft 10-3, the spiral blade 10-4 extending along the length direction of the rotating shaft 10-3. One end of the lifting pipe 10-1 faces the aerobic zone 19, and the other end faces the reflow tank 20. The rotating shaft 10-3 is provided in the lifting pipe 10-1, and the lifting end of the rotating shaft 10-3 is provided in the aerobic zone 19. A gap is provided between the spiral blade 10-4 and the inner wall of the lifting pipe 10-1. Figure 2 and Figure 4 As shown, an air brush device 21 is installed below the end of the riser 10-1 facing the aerobic zone 19. The air brush device 21 includes a vertically arranged air collecting cylinder 21-1 with an open top. The bottom of the air collecting cylinder 21-1 is connected to the first blower 26 via an air inlet pipe 21-2. A rotatably connected cover plate 21-3 is installed on the top of the air collecting cylinder 21-1. This cover plate 21-3 has four through holes 21-4, and two elastic elements 21-5 are installed between the cover plate 21-3 and the top of the air collecting cylinder 21-1. These elastic elements 21-5 are springs. The stirring device 6, the first liquid level gauge 5, the second liquid level gauge 11, the motor 10-2, the first valve 8, the second valve 7, the second blower 14-2, and the first blower 26 are all electrically connected to the control system 4.

[0036] This embodiment also provides a method for treating food processing wastewater, which uses the sewage treatment device as described above for treatment, and specifically includes the following steps:

[0037] S1, after the wastewater enters the anaerobic zone 17 for treatment, the wastewater carries the carrier 15 into the anoxic zone 18 for denitrification treatment;

[0038] S2, the wastewater and the carrier 15 then enter the aerobic zone 19, and the wastewater treated in the aerobic zone 19 is discharged through the outlet pipe 13;

[0039] S3. Part of the wastewater and the carrier 15 in the aerobic tank 19 are lifted into the reflow tank 20 by the lifting device 10. The wastewater in the reflow tank 20 flows back to the anoxic zone 18 through the first connecting pipe 23. The carrier 15 in the reflow tank 20 returns to the anaerobic zone 17 through the second connecting pipe 24.

[0040] The dissolved oxygen in the aerobic zone 19 is 1-4 mg / L, and the air-water volume ratio is 5-15:1. The density of the carrier 15 is 1-1.01 g / cm 3 The filling rate of the carrier 15 is 10 to 40%.

[0041] Food processing wastewater is characterized by high pollutant concentrations and complex composition, with high concentrations of organic matter, nitrogen, and phosphorus. Food processing wastewater first enters the anaerobic zone 17, where carriers 15 adsorb insoluble impurities in the wastewater. Some particulate impurities adhere to the surface of carriers 15, performing the initial pollutant removal process. Furthermore, because carriers 15 are in an anaerobic environment, microorganisms on carriers 15 decompose dissolved organic matter in the wastewater. The anaerobic bacteria on carriers 15 convert large soluble organic molecules into small organic molecules, making them more readily available for subsequent reactions and absorption. After treatment in the anaerobic zone 17, the carriers follow the wastewater through the first flow tunnel 3 into the anoxic zone 18. Denitrifying bacteria attached to carriers 15, using both soluble and insoluble organic matter as a carbon source, convert the large amounts of nitrate nitrogen in the wastewater into nitrogen gas, which is released into the air, achieving denitrification. The wastewater and carriers then flow through the second flow tunnel 22 into the aerobic zone 19. In aerobic zone 19, aeration plates 14-1 at the bottom provide sufficient dissolved oxygen for carriers 15. Generally, the dissolved oxygen level is controlled at 1-4 mg / L, and the air-water ratio is controlled at 5-15:1. In the aerobic tank, aerobic bacteria on carriers 15 begin to decompose ammonia nitrogen and remaining soluble and insoluble organic matter. When the dissolved oxygen level in aerobic zone 19 is controlled below 2 mg / L, the inner layer of carriers 15 becomes anaerobic and anoxic, while the surface layer of carriers 15 becomes aerobic. Therefore, on the same carrier 15, under the low dissolved oxygen conditions of aerobic zone 19, each carrier 15 forms a separate biochemical system that effectively and collaboratively removes organic matter, nitrogen, phosphorus, and other substances. Because a first interception net 12 and a lifting device 10 are located at the end of aerobic zone 19, carriers 15 are prevented from being lost. Driven by motor 10-2, shaft 10-3 rotates spiral blades 10-4, simultaneously lifting carrier 15 and sewage located at the mouth of riser 10-1 in aerobic zone 19 upward into recirculation trough 20. The rotational speed of shaft 10-3 can be varied by adjusting motor 10-2. At a slower speed, carrier 15 is lifted into recirculation trough 20, while sewage flows out through the gap between spiral blades 10-4 and the inner wall of riser 10-1. At a faster speed, carrier 15 and sewage are lifted into recirculation trough 20 together. Due to the interception of carrier 15 by second interception net 9, sewage in recirculation trough 20 flows back to anoxic zone 18 via first connecting pipe 23 to ensure denitrification, while carrier 15 returns to anaerobic zone 17 via second connecting pipe 24, thereby ensuring the circulation of carrier 15. When the sewage treatment device operates normally, a small amount of gas is blown into the gas collecting cylinder 21-1 through the first blower 26. The gas flows upward into the lifting pipe 10-1 through the through hole 21-4 on the cover plate 21-3, which can assist the spiral blade 10-4 in lifting the carrier.When the lifting device 10 needs to increase the lifting amount or the lifting pipe 10-1 is blocked, the gas supply volume can be increased. When the gas pressure in the gas collecting cylinder 21-1 reaches a certain level, the cover 21-3 will be opened outward, and the gas will rush out instantly and enter the lifting pipe 10-1, strongly flushing the lifting pipe 10-1, thereby clearing the blockage.

[0042] Since the microorganisms on the carrier 15 are not easily discharged, the microbial age cycle is long, and more protozoa and metazoa will appear. Protozoa, metazoa and bacteria form a complete biological chain system, that is, protozoa feed on bacteria and organic matter, and metazoa feed on protozoa and organic matter. Phosphorus will be enriched in metazoans during this process. Finally, when the metazoans die, they fall off the carrier to form insoluble sludge, which is discharged regularly. Therefore, the treatment method of food processing wastewater in this embodiment is completely different from the anaerobic phosphorus release, aerobic phosphorus absorption and sludge removal principles of the conventional A2O activated sludge method. The phosphorus removal in this embodiment is through the biological chain on the carrier 15. The amount of sludge discharged is smaller, the sludge disposal fee is lower, and the effect is more obvious. Therefore, the carrier 15 is continuously circulated in the anaerobic zone 17, the anoxic zone 18, and the aerobic zone 19 to comprehensively remove pollutants such as organic matter, nitrogen and phosphorus, which is particularly suitable for the application scenario of food processing wastewater.

[0043] The contents described in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the invention, and are not used to limit the scope of the invention. After reading the present invention, various equivalent modifications to the embodiments made by those skilled in the art fall within the scope defined by the claims attached to the present invention.

Claims

1. A sewage treatment device comprising an anaerobic zone (17), an anoxic zone (18) and an aerobic zone (19), wherein a first interception net (12) is provided in the aerobic zone (19), and the first interception net (12) is arranged around a water outlet pipe (13) of the aerobic zone (19); characterized in that: A reflow trough (20) is provided in the aerobic zone (19), the reflow trough (20) is connected to the aerobic zone (19) via a lifting device (10), and the reflow trough (20) and the outlet pipe (13) are respectively provided on both sides of the first interception net (12); A second interception net (9), a first connecting pipe (23) and a second connecting pipe (24) are provided on the side wall of the reflux trough (20); the second interception net (9) is provided at the first connecting pipe (23), and the height of the second connecting pipe (24) is higher than that of the first connecting pipe (23); The reflow trough (20) is connected to the anoxic zone (18) via a first connecting pipe (23), and the reflow trough (20) is connected to the anaerobic zone (17) via a second connecting pipe (24); A carrier (15) is provided in the anaerobic zone (17), and a stirring device (6) is provided in the anaerobic zone (17), the anoxic zone (18) and the reflow tank (20); The lifting device (10) comprises an inverted U-shaped lifting pipe (10-1), a motor (10-2), a rotating shaft (10-3) mounted on the power output end of the motor (10-2), and a spiral blade (10-4) arranged on the rotating shaft (10-3), wherein the spiral blade (10-4) extends along the length direction of the rotating shaft (10-3); one end of the lifting pipe (10-1) faces the reflow groove (20), and the other end faces the aerobic zone (19); the rotating shaft (10-3) is arranged in the lifting pipe (10-1), and the lifting end of the rotating shaft (10-3) is arranged in the aerobic zone (19); a gap is provided between the spiral blade (10-4) and the inner wall of the lifting pipe (10-1); An air brush device (21) is provided below the end of the lifting pipe (10-1) facing the aerobic zone (19). The air brush device (21) comprises a vertically arranged gas collecting cylinder (21-1). The top of the gas collecting cylinder (21-1) is open, and the top of the gas collecting cylinder (21-1) faces the end of the lifting pipe (10-1). The bottom of the gas collecting cylinder (21-1) is connected to the first blower (26) via an air inlet pipe (21-2). A rotatably connected cover plate (21-3) is provided on the top of the gas collecting cylinder (21-1). The cover plate (21-3) is provided with a plurality of through holes (21-4), and at least one elastic element (21-5) is provided between the cover plate (21-3) and the top of the gas collecting cylinder (21-1).

2. The sewage treatment device according to claim 1, characterized in that: A first liquid level gauge (5) is provided in the anaerobic zone (17), and a second liquid level gauge (11) is provided in the aerobic zone (19). The second liquid level gauge (11) is provided at the water outlet pipe (13).

3. The sewage treatment device according to claim 2, characterized in that: The first connecting pipe (23) is provided with a first valve (8), the second connecting pipe (24) is provided with a second valve (7), and the stirring device (6), the first liquid level gauge (5), the second liquid level gauge (11), the lifting device (10), the first valve (8), the second valve (7), and the aeration device (14) in the aerobic zone (19) are all electrically connected to the control system (4).

4. The sewage treatment device according to any one of claims 1 to 3, characterized in that: The cross section of the aerobic zone (19) is a rectangle, and the ratio of the width to the length of the rectangle is greater than or equal to 1:

5.

5. The sewage treatment device according to any one of claims 1 to 3, characterized in that: The reflow trough (20) is arranged on the side wall of the aerobic zone (19), and the side of the reflow trough (20) provided with the first connecting pipe (23) is arranged adjacent to the anoxic zone (18), and the side of the reflow trough (20) provided with the second connecting pipe (24) is arranged adjacent to the anaerobic zone (17).

6. A method for treating food processing wastewater, characterized in that: The sewage treatment device according to any one of claims 1 to 5 is used for treatment, which specifically comprises the following steps: S1, after the wastewater enters the anaerobic zone (17) for treatment, the wastewater carries the carrier (15) into the anoxic zone (18) for denitrification treatment; S2, wastewater and carrier (15) then enter the aerobic zone (19), and the wastewater treated in the aerobic zone (19) is discharged through the outlet pipe (13); S3. Part of the wastewater and the carrier (15) in the aerobic zone (19) are lifted into the reflow trough (20) through the lifting device (10). The wastewater in the reflow trough (20) flows back to the anoxic zone (18) through the first connecting pipe (23). The carrier (15) in the reflow trough (20) returns to the anaerobic zone (17) through the second connecting pipe (24).

7. The method for treating food processing wastewater according to claim 6, wherein: The dissolved oxygen in the aerobic zone (19) is 1-4 mg / L, the air-water volume ratio is 5-15:1; the density of the carrier (15) is 1-1.01 g / cm 3 , the filling rate of the carrier (15) is 10 to 40%.

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