Double-sludge reflux sewage treatment device for enhancing nitrogen and phosphorus removal

Abstract

The invention discloses a double-sludge reflux sewage treatment device for enhancing nitrogen and phosphorus removal, and belongs to sewage treatment equipment. The invention relates to a double-sludge reflux sewage treatment device for enhancing nitrogen and phosphorus removal, which comprises a water inlet pipe, a raw water tank, a sewage lifting pump, a water flow pipeline assembly fitting system, a sewage treatment combination unit, a two-stage solid-liquid separation area, a sludge reflux and discharge unit, a water outlet pipe and an equipment room PLC (Programmable Logic Controller) module assembly, an oscillation device and a cloth hanging type biological carrier piece are arranged on the first-stage aerobic tank, the oscillation device is connected with the cloth hanging type biological carrier piece, and biological stuffing is arranged on the cloth hanging type biological carrier piece. The cloth hanging type biological carrier part is driven by the oscillation device to vibrate, aged and deactivated sludge on the surface of the biological filler is vibrated off, growth and renewal of a biological membrane on the biological filler are facilitated, and double reflux of the sludge is realized, so that nitrification and phosphorus uptake reactions are more thorough.

Description

Technical Field

[0001] The invention relates to a sewage treatment device, in particular to a double-sludge return sewage treatment device with enhanced denitrification and dephosphorization. Background Art

[0002] With the acceleration of industrialization and urbanization, water pollution is becoming increasingly serious, especially nitrogen and phosphorus pollution, which is not only related to the sustainable use of water resources, but also directly affects our ecological environment. To this end, some sewage treatment equipment has appeared on the market, such as the sewage treatment equipment with announcement numbers CN218058731U and CN214653942U. This type of sewage treatment equipment is based on A 2 O process produced, A 2 The O process combines A / O (Anoxic-Oxic) biological denitrification and A 2 Anaerobic-Oxic (Anaerobic-Oxic) biological phosphorus removal has the characteristics of simultaneous nitrogen and phosphorus removal. However, when this type of sewage treatment equipment is used, aged sludge in the sewage or sticky impurities in the influent are easily covered on the biological fillers in the aerobic tank. As the amount of covered sludge increases, the contact between the aerobic bacteria and the sewage is limited, which greatly reduces the sewage treatment efficiency. Aged sludge and adhered impurities on the biological fillers need to be regularly removed, which is difficult to handle.

[0003] And, A 2 Nitrogen and phosphorus removal in sewage treatment processes involve multiple biochemical reactions such as nitrification and denitrification, phosphorus absorption and release, and each reaction has different requirements for environmental conditions, substrate types, and microbial composition. Phosphorus-accumulating bacteria in anaerobic tanks and denitrifying bacteria in anoxic tanks are short-sludge-age microorganisms, which are beneficial for phosphorus removal and denitrification. In contrast, autotrophic nitrifying bacteria in aerobic tanks have a slow growth rate and a long generation cycle. To make autotrophic nitrifying bacteria the dominant bacterial community, a long sludge age of 20 to 30 days is required in the aerobic stage. However, a long sludge age also results in too little discharge of phosphorus-containing sludge. Moreover, a high sludge age may cause phosphorus to be released back from the phosphorus-containing sludge, which is not conducive to phosphorus removal in the system. In the denitrification and phosphorus removal process, denitrifying bacteria and phosphorus-accumulating bacteria are mixed and symbiotic, competing for carbon sources. Denitrifying bacteria preferentially take up carbon sources, and insufficient carbon sources in the anaerobic stage will inhibit phosphorus release by phosphorus-accumulating bacteria, resulting in poor phosphorus removal. To ensure good phosphorus removal, the anaerobic stage needs to have sufficient carbon source for phosphorus-accumulating bacteria to absorb. Generally, the anaerobic tank (SP / SBOD) ratio is controlled within 0.06, and the sludge load is controlled above 0.10 kgBOD5 / (kgMLSS·d).

[0004] A 2The main problem of the O process denitrification and phosphorus removal process is the contradiction between the long sludge age for nitrification and the short sludge age for phosphorus release and denitrification, the contradiction between the carbon source allocation for denitrification and phosphorus release, and the sludge return that destroys the anaerobic environment, affecting the phosphorus removal problem. Since the three strains of bacteria (nitrifying bacteria, denitrifying bacteria, and polyphosphate bacteria) that realize different functions cannot grow under their respective optimal conditions, the carbon source contradiction and the reflux NOx-N problem cannot be fundamentally solved, denitrification and phosphorus removal restrict each other, and the nitrogen and phosphorus removal rates cannot reach the highest at the same time. In order to solve the above problems, the present invention proposes a dual sludge return sewage treatment device and a matching system for strengthening denitrification and phosphorus removal, and aims to solve the problem that aging sludge in the original sewage treatment equipment is easily covered on the biological filler. The dual sludge return makes nitrification and phosphorus absorption reactions more thorough. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a dual sludge return sewage treatment device with enhanced denitrification and phosphorus removal that can overcome the above problems or at least partially solve the above problems.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A dual-sludge return sewage treatment device for enhanced nitrogen and phosphorus removal includes an inlet pipe, a raw water tank, a sewage lifting pump, a water flow pipe assembly accessory system, a sewage treatment assembly unit, a two-stage solid-liquid separation zone, a sludge return and discharge unit, a supporting series of testing instruments, an outlet pipe, and a PLC controller module component in the equipment room. Sewage flows into the raw water tank through the inlet pipe. The sewage lifting pump is located in the raw water tank. The sewage lifting pump and the water flow pipe assembly accessory system lift the sewage in the raw water tank and then flows it into the sewage treatment assembly unit and the solid-liquid separation zone in sections. The sewage is treated, clarified, and disinfected to meet standards before being discharged through the outlet pipe. The sewage treatment assembly unit and the sludge return and discharge unit are connected via the water flow pipe assembly accessory system.

[0008] The water flow pipe assembly accessory system includes water flow pipes and flow meters and flow distribution regulating valves installed on the water flow pipes at different locations. The flow meters and flow distribution regulating valves are connected to the PLC controller module assembly between the equipment through an electric control circuit. The sewage treatment combined unit has a first-stage aerobic tank, which is equipped with a hanging cloth-type biological carrier and an aeration facility.

[0009] The first-stage aerobic pool is provided with an oscillating device, which is connected to the hanging cloth type biological carrier component and can drive the hanging cloth type biological carrier component to shake horizontally and laterally left and right.

[0010] Furthermore, the sewage treatment combined unit also includes a pre-denitrification tank, an anaerobic tank, a first-stage solid-liquid separation zone, an anoxic tank, a second-stage aerobic tank, and a second-stage solid-liquid separation zone, wherein the pre-denitrification tank, anaerobic tank, first-stage aerobic tank, first-stage solid-liquid separation zone, anoxic tank, second-stage aerobic tank, second-stage solid-liquid separation zone, and equipment room are arranged in sequence from front to back on the entire sewage treatment device.

[0011] The sludge return and discharge unit is installed between the pre-denitrification tank, the first-stage solid-liquid separation zone, the anoxic tank, and the second-stage solid-liquid separation zone through a sludge return pipeline.

[0012] The supporting series of detection instruments include a dissolved oxygen detector, an oxidation-reduction potential detector and a sludge concentration detector. The first-stage aerobic tank and the second-stage aerobic tank of the anaerobic tank are respectively equipped with a dissolved oxygen detector, the anaerobic tank and the anoxic tank of the pre-denitrification tank are respectively equipped with an oxidation-reduction potential detector, and the pre-denitrification tank and the anoxic tank are respectively equipped with a sludge concentration detector. The supporting series of detection instruments are connected to the PLC controller module assembly between the equipment through the electric control circuit, and the PLC controller module assembly between the equipment and the supporting series of detection instruments are connected to the external power supply through the corresponding circuits.

[0013] Furthermore, the sludge return and discharge unit includes a first-stage solid-liquid separation area sludge return pipe group, a first-stage solid-liquid separation area sludge discharge pipe group, a first-stage solid-liquid separation area sludge return carbon source pipe group, a second-stage solid-liquid separation area sludge return pipe group and a second-stage solid-liquid separation area sludge discharge pipe group.

[0014] A pump and an electric valve are installed on the sludge return pipe group of the first-stage solid-liquid separation zone. One end of the sludge return pipe group of the first-stage solid-liquid separation zone is connected to the first-stage solid-liquid separation zone (27) through the pump and the electric valve, and the other end is connected to the pre-denitrification tank (10). The sludge return pipe group of the first-stage solid-liquid separation zone can return the sludge from the first-stage solid-liquid separation zone (27) to the pre-denitrification tank (10);

[0015] A pump (shared with the sludge return) and an electric valve are installed on the carbon source pipe group of the return sludge in the first-stage solid-liquid separation zone. One end of the carbon source pipe group of the return sludge in the first-stage solid-liquid separation zone is connected to the first-stage solid-liquid separation zone (27) through the pump and the electric valve, and the other end is connected to the anoxic tank (12). The carbon source pipe group of the return sludge in the first-stage solid-liquid separation zone can return the carbon source in the return sludge in the first-stage solid-liquid separation zone to the anoxic tank (12);

[0016] The first-stage solid-liquid separation zone sludge discharge pipe group is installed at the bottom of the first-stage solid-liquid separation zone (27). The first-stage solid-liquid separation zone sludge discharge pipe group is equipped with a pump (shared with the sludge return) and an electric valve, which can discharge the sludge in the first-stage solid-liquid separation zone (27) to the outside;

[0017] A pump and an electric valve are installed on the second-stage solid-liquid separation zone sludge return pipe group. One end of the second-stage solid-liquid separation zone sludge return pipe group is connected to the second-stage solid-liquid separation zone (28), and the other end is connected to the anoxic tank (12). The second-stage solid-liquid separation zone sludge return pipe group can return the sludge in the second-stage solid-liquid separation zone (28) to the anoxic tank (12);

[0018] The second-stage solid-liquid separation zone sludge discharge pipe group is installed at the bottom of the second-stage solid-liquid separation zone (28). The second-stage solid-liquid separation zone sludge discharge pipe group is equipped with a pump (shared with the sludge return) and an electric valve, which can discharge the sludge in the second-stage solid-liquid separation zone (28) to the outside.

[0019] Preferably, the oscillation device comprises a cylinder assembly, a sliding support frame, a smooth inner-penetrating rod, a support plate and a tendon buffer pad. The support plate is mounted on the left and right edges of the first-stage aerobic pool, both ends of the smooth inner-penetrating rod are mounted on the support plate, the sliding support frame is mounted on the smooth inner-penetrating rod, one end of the sliding support frame is connected to the cylinder assembly, and the other end of the sliding support frame is equipped with a tendon buffer pad. The cylinder assembly can push the sliding support frame to slide horizontally left and right on the smooth inner-penetrating rod.

[0020] Furthermore, the sliding support frame is provided with a crossbeam, and the cloth-hanging biological carrier component can be a linear hanging biological carrier component or a soft cloth-hanging biological carrier component, and the cloth-hanging biological carrier component is vertically hung on the crossbeam of the sliding support frame.

[0021] Furthermore, the sliding support frame can be provided with an L-shaped stirring rod, one end of the L-shaped stirring rod is connected to the side of the sliding support frame, and the other end of the L-shaped stirring rod is provided with a brush head component, and the installation area of ​​the brush head component is located above the aeration head assembly in the aeration facility at the bottom of the first-stage aerobic tank.

[0022] Preferably, the aeration head assembly includes a microporous aeration head and a sludge collecting piece. The aeration head assembly is connected to the blower aeration equipment through an aeration pipe. A variable frequency flow distribution regulating valve is provided on the aeration pipe. The variable frequency flow distribution regulating valve is connected to the equipment inter-device PLC controller module assembly through an electric control circuit. The end of the aeration pipe is connected to the microporous aeration head. The sludge collecting piece is installed around the lower part of the microporous aeration head. The sludge collecting piece can collect or gather sludge and other debris settled on the microporous aeration head.

[0023] Furthermore, a soft arc-shaped film member is provided on the upper top surface of the microporous aeration head, and aeration through holes are provided on the soft arc-shaped film member. When the aeration amount delivered by the aeration pipeline to the microporous aeration head is adjusted in large or small amounts through the frequency conversion flow distribution regulating valve, the soft arc-shaped film member on the microporous aeration head can be shaken, thereby shaking off sludge and debris settled on the soft arc-shaped film member in the microporous aeration head, and these sludge and debris can fall into the sludge collecting member.

[0024] Furthermore, the water outlets of both the first-stage aerobic tank and the second-stage aerobic tank are provided with slag-blocking sleeve assemblies, which include an outer sleeve, an inner sleeve and an adapter. The outer sleeve is fixedly mounted on the outside of the inner sleeve through a fixed bracket, the adapter is mounted on the inner sleeve, and the inner sleeve is provided with a water outlet pipe. This design can effectively prevent scum, foam, etc. on the surface of the aerobic tank from flowing into the solid-liquid separation area.

[0025] Preferably, the bottom of the outer sleeve is funnel-shaped, and the bottom end of the funnel-shaped inner sleeve is connected to a water outlet pipe.

[0026] Furthermore, the pre-denitrification tank, anaerobic tank and anoxic tank are all provided with a submersible stirring assembly, which includes a bracket, a guide rod and a submersible stirrer. The bracket is installed on the pre-denitrification tank, anaerobic tank and anoxic tank, one side of the guide rod is installed on the bracket, and the submersible stirrer is installed on the other side of the guide rod. A U-shaped slot is provided on the bracket, and the direction of the submersible stirrer can be changed by rotating the guide rod in the U-shaped slot. This design can prevent the substances in the pre-denitrification tank, anaerobic tank and anoxic tank from lateral aggregation, making the center of gravity of the entire dual sludge return sewage treatment device unstable, causing lateral tilt or deflection.

[0027] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0028] 1. Use a pre-denitrification tank in front of the anaerobic tank of the sewage treatment AO process to remove NO in the return sludge through some organic matter in the influent. X -N denitrification can reduce NO X -N competes with the carbon source for phosphorus release by phosphate-accumulating bacteria in the anaerobic zone, making the anaerobic state of the anaerobic tank better and enhancing the phosphorus removal effect;

[0029] Biological phosphorus removal and biological denitrification use independent sludge return and discharge systems to solve the contradiction between denitrification and phosphorus removal sludge age in the original sewage treatment equipment;

[0030] Arranging biological fillers in the first-stage aerobic tank is conducive to enriching nitrifying bacteria with a short generation cycle and enhancing the nitrification reaction effect;

[0031] The use of staged water inflow makes the water ratio adjustable, allowing part of the influent to enter the pre-denitrification tank to remove the nitrate nitrogen carried by the return sludge and damage the anaerobic phosphorus release environment; part of the influent enters the anaerobic zone, where the organic matter in the sewage is converted by microorganisms into intermediate products such as volatile fatty acids (VFA) under anaerobic conditions, and synthesized into internal carbon sources such as polyhydroxyalkanoates (PHA), which are stored in the microorganisms; then enters the first aerobic zone. Due to sufficient dissolved oxygen and rich ammonia nitrogen substrate, the first aerobic zone mainly undergoes nitrification, converting ammonia nitrogen into nitrate nitrogen. A small amount of organic matter is oxidized here, while most of the organic matter remains in the system and then returns to the anoxic tank with the internal carbon source of the return sludge from the first solid-liquid separation zone; in the anoxic tank, denitrification is carried out using the internal carbon source (PHA, etc.) stored in the anaerobic zone to reduce nitrate nitrogen to nitrogen gas, achieving denitrification; because the anoxic zone utilizes the internal carbon source stored in the anaerobic zone for denitrification, efficient utilization of organic matter is achieved, reducing the demand for external carbon sources;

[0032] In addition, the first-stage aerobic tank is located in the front, which can convert most of the ammonia nitrogen in the influent into nitrate nitrogen. The anoxic tank is located in the back, and the nitrate nitrogen carried by the effluent of the first-stage aerobic tank flows into the anoxic tank by gravity, eliminating the need for nitrification liquid backflow and saving energy consumption. The purpose of setting up the second-stage aerobic tank after the anoxic tank is to further remove ammonia nitrogen in the water. The mixed liquid then enters the second-stage solid-liquid separation zone. The sludge return pipe group of the second-stage solid-liquid separation zone returns the nitrate nitrogen produced in the second-stage aerobic section and the sludge in the second-stage solid-liquid separation zone to the anoxic section, maintaining the biomass in the system. It can also bring the internal carbon source in the microorganisms back to the anoxic section, further reducing the demand for external carbon sources.

[0033] 2. By installing an oscillating device in the first-stage aerobic tank, the oscillating device drives the hanging cloth-type biological carrier to shake, which can shake off the sludge on the biological filler, thereby preventing aged sludge from adhering to the surface of the biofilm, affecting the contact between aerobic bacteria and sewage, and reducing the reaction efficiency; at the same time, the shaking of the hanging cloth-type biological carrier is conducive to the contact between aerobic bacteria and sewage, which can increase the nitrification reaction effect;

[0034] The design of the inner and outer sleeve type slag retaining sleeve assembly can intercept the scum and foam on the surface of the aerobic tank inside the aerobic tank, and the sewage flows from the bottom of the outer sleeve into the inner sleeve to the next process. This design can prevent the debris in the sewage from flowing into the outlet pipe of the subsequent pipeline and causing blockage, and can also prevent the debris in the sewage from flowing into the next process and affecting the treatment effect;

[0035] 3. By installing a sludge collecting piece around the lower part of the microporous aeration head, the sludge collecting piece can collect or gather the sludge and other debris settled on the microporous aeration head, which can prevent the sludge from accumulating on the microporous aeration head and prevent the air outlet holes on the microporous aeration head from being blocked by sludge;

[0036] By adjusting the aeration volume delivered from the aeration pipe to the microporous aeration head through the variable frequency flow distribution regulating valve, the soft curved membrane on the microporous aeration head can be shaken, thereby shaking off the sludge and debris settled on the soft curved membrane in the microporous aeration head. These sludge and debris can fall into the sludge collecting piece, which can effectively prevent the sludge from settling on the aeration head.

[0037] The L-shaped stirring rod and brush head arranged on the support rod can stir the sewage on the microporous aeration head, which can better clean the sludge on the microporous aeration head and ensure its excellent aeration effect.

[0038] In summary, the present invention can avoid the adhesion of aged sludge on the surface of biological filler through the design of oscillation device; the use of slag retaining sleeve design can prevent the blockage of water outlet pipe; the sludge collecting part design outside the microporous aeration head can collect sludge and debris settled on the microporous aeration head; at the same time, the present invention can significantly improve the removal efficiency of nitrogen and phosphorus in sewage by optimizing the design of sewage treatment process and corresponding parameters in the entire sewage treatment device, such as influent carbon source distribution, hydraulic retention time (HRT), sludge age (SRT), dissolved oxygen (DO) concentration, etc. At the same time, the device or system utilizes internal carbon source for denitrification, reduces the demand for external carbon source, and the sludge output is relatively small, thereby reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is an overall three-dimensional schematic diagram of a dual-sludge return sewage treatment device with enhanced nitrogen and phosphorus removal proposed by the present invention;

[0040] Figure 2 This is a schematic diagram of the process flow of a double sludge return sewage treatment device with enhanced nitrogen and phosphorus removal proposed by the present invention;

[0041] Figure 3 This is a front schematic diagram of a horizontal transverse longitudinal section of a dual sludge return sewage treatment device for enhanced nitrogen and phosphorus removal proposed by the present invention when viewed from the left front to the right;

[0042] Figure 4 This is a three-dimensional schematic diagram of the location of the oscillating device in a dual sludge return sewage treatment device for enhanced nitrogen and phosphorus removal proposed by the present invention;

[0043] Figure 5 This is a three-dimensional schematic diagram of the location of the microporous aeration head in a dual sludge return sewage treatment device for enhanced nitrogen and phosphorus removal proposed by the present invention;

[0044] Figure 6 This is a partial perspective schematic diagram of an L-shaped stirring rod and a brush head member added to the side of a sliding support rod in a dual sludge return sewage treatment device for enhanced denitrification and phosphorus removal proposed by the present invention;

[0045] Figure 7 This is a three-dimensional schematic diagram of the location of the slag retaining sleeve in a dual sludge return sewage treatment device for enhanced denitrification and phosphorus removal proposed by the present invention;

[0046] Figure 8 This is a top view schematic diagram of the location of the slag retaining sleeve in a dual sludge return sewage treatment device for enhanced denitrification and phosphorus removal proposed by the present invention;

[0047] In the figure: 1. Raw water tank; 2. Sewage lifting pump; 3. Water flow pipe assembly accessory system; 4. Sludge return and discharge unit; 5. Flow meter; 6. Flow distribution regulating valve; 7. First-stage aerobic tank; 8. Cloth-type biological carrier component; 9. Oscillating device; 10. Pre-denitrification tank; 11. Anaerobic tank; 12. Anoxic tank; 13. Second-stage aerobic tank; 14. Cylinder assembly; 15. Sliding support frame; 16. Smooth inner rod; 17. Tendon buffer pad; 18. Crossbeam; 19. L-shaped stirring rod; 20. Brush head component; 21. Microporous aeration head; 22. Sludge collecting component; 23. Outer sleeve; 24. Inner sleeve; 25. Water outlet pipe; 26. Submersible agitator; 27. First-stage solid-liquid separation zone; 28. Second-stage solid-liquid separation zone. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0049] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0050] Example 1:

[0051] Reference Figure 1-Figure 3A double sludge return sewage treatment device for enhanced denitrification and phosphorus removal comprises a raw water tank 1, a sewage lifting pump 2, a water flow pipeline assembly accessory system 3, a flow meter 5, a flow distribution regulating valve 6, a pre-denitrification tank 10, an anaerobic tank 11, a first-stage aerobic tank 7, a first-stage solid-liquid separation zone, an anoxic tank 12, a second-stage aerobic tank 13, sludge return from the first-stage solid-liquid separation zone, sludge discharge from the first-stage solid-liquid separation zone, a carbon source in the return sludge from the first-stage solid-liquid separation zone, sludge return from the second-stage solid-liquid separation zone, sludge discharge from the second-stage solid-liquid separation zone, aeration in the first-stage aerobic tank 7, aeration in the second-stage aerobic tank 13, a dissolved oxygen (DO) detector in the anaerobic tank 11, a dissolved oxygen (DO) detector in the first-stage aerobic tank 7, a dissolved oxygen (DO) detector in the second-stage aerobic tank 13, a redox electrode in the pre-denitrification tank 10 The sludge concentration detector of the anoxic tank 12 is composed of an oxidation-reduction potential (ORP) detector, an anaerobic tank 11 oxidation-reduction potential (ORP) detector, a pre-denitrification tank 10 sludge concentration (MLSS) detector, and an anoxic tank 12 sludge concentration (MLSS) detector. The sewage in the raw water tank 1 is lifted by the sewage lifting pump 2 and then enters the pre-denitrification tank 10 and the anaerobic tank 11 for treatment in sections. At the same time, the sludge return from the first-stage solid-liquid separation zone also enters the pre-denitrification tank 10. The effluent from the first-stage aerobic tank 7 passes through the first-stage solid-liquid separation zone and the clarified water flows by gravity into the anoxic tank 12 and the second-stage aerobic tank 13 for treatment. At the same time, the return sludge from the second-stage solid-liquid separation zone and the carbon source in the return sludge from the first-stage solid-liquid separation zone also enter the anoxic tank 12. The effluent from the second-stage aerobic tank 13 is clarified in the second-stage solid-liquid separation zone and then disinfected and discharged after meeting the standards.

[0052] The sewage lifting pump 2 is a submersible sewage pump with variable frequency flow rate regulation. The sewage lifting pump 2 is connected to the water inlet pipe. A flow meter 5 is installed on the water inlet pipe. The frequency of the sewage lifting pump 2 is associated with the water inlet flow value set by the system through the flow meter 5 and the programmable controller (PLC between equipment) module, and is automatically adjusted to maintain it at a relatively constant value. The water inlet pipe enters the system in two sections, one section enters the pre-denitrification tank 10, and the other section enters the anaerobic tank 11, and the water inlet ratio can be adjusted by the flow distribution regulating valve 6;

[0053] The pre-denitrification tank 10 is fed with water from the top. A submersible agitator 26 is installed in the pre-denitrification tank 10. The submersible agitator 26 is one of a paddle type, a propeller type, and a turbine type. An oxidation-reduction potential (ORP) detector and a sludge concentration (MLSS) detector are installed in the pre-denitrification tank 10. The oxidation-reduction potential (ORP) of the pre-denitrification tank 10 does not exceed 50mV. The mixed liquor suspended solids (MLSS) concentration of the pre-denitrification tank 10 is 2-4g / L. The hydraulic retention time of the pre-denitrification tank 10 is 1-2h. The pre-denitrification tank 10 is connected to the anaerobic tank 11 through a baffle with holes in the bottom, and the effluent flows into the anaerobic tank 11 by gravity.

[0054] The anaerobic tank 11 is fed with water from the bottom. A submersible agitator 26 is installed in the anaerobic tank 11. The submersible agitator 26 is one of a paddle type, a propeller type, and a turbine type. An oxidation-reduction potential (ORP) detector and a dissolved oxygen (DO) detector are installed in the anaerobic tank 11. The hydraulic retention time of the anaerobic tank 11 is 1-2 hours. The ORP of the anaerobic tank 11 is not higher than -100 mV. The dissolved oxygen in the anaerobic tank 11 is not higher than 0.2 mg / L. The anaerobic tank 11 is connected to the guide tube of the first-stage aerobic tank 7 through a partition with a hole in the upper portion. The effluent flows from the bottom into the first-stage aerobic tank 7 by gravity.

[0055] The first-stage aerobic tank 7 has a water inlet mode of top inlet, and an aeration head assembly and biological filler are arranged in the first-stage aerobic tank 7. The aeration head assembly can be one or more combinations of disc type, tube type, and hose type. The biological filler can be one or more combinations of combined fiber filler, soft fiber filler, porous suspended ball filler, obliquely suspended porous suspended filler, and PPC polyurethane sponge filler. A dissolved oxygen (DO) detector is installed in the first-stage aerobic tank 7. The hydraulic retention time of the first-stage aerobic tank 7 is 5-8h. The dissolved oxygen in the first-stage aerobic tank 7 is not less than 2mg / L. Water is discharged from the upper part of the first-stage aerobic tank 7. The effluent passes through a water collecting pipe with a slag retaining sleeve and is connected to the first-stage solid-liquid separation zone through a partition. The effluent flows into the first-stage solid-liquid separation zone by gravity.

[0056] The first-stage solid-liquid separation zone can be of either vertical flow or radial flow type, wherein the radial flow solid-liquid separation zone is equipped with a sludge scraping and slag scraping device; the bottom sludge collection area of ​​the first-stage solid-liquid separation zone is equipped with a sludge pump, a return sludge electric valve, a sludge discharge electric valve, and a return sludge internal carbon source electric valve; after the sludge and water are separated in the first-stage solid-liquid separation zone, the clear water is collected by the water collection weir and then flows from the top through the partition into the anoxic tank 12 by gravity;

[0057] The anoxic tank 12 is fed with water from the top. A submersible agitator 26 is installed in the anoxic tank 12. The submersible agitator 26 is one of a paddle type, a propeller type, and a turbine type. An oxidation-reduction potential (ORP) detector and a sludge concentration (MLSS) detector are installed in the anoxic tank 12. The hydraulic retention time of the anoxic tank 12 is 6-9 hours. The ORP of the anoxic tank 12 is not higher than 50mV. The mixed liquor suspended solids (MLSS) concentration of the anoxic tank 12 is 3.5-5g / L. The anoxic tank 12 is connected to the second-stage aerobic tank 13 through a partition through a hole opened at the bottom. The effluent flows into the second-stage aerobic tank 13 by gravity.

[0058] The second-stage aerobic tank 13 is provided with an aeration head assembly, which can be a disc type, a tube type, a hose type, or a combination of more than one of them. A dissolved oxygen (DO) detector is installed in the second-stage aerobic tank 13. The hydraulic retention time of the second-stage aerobic tank 13 is 2-4 hours. The dissolved oxygen in the second-stage aerobic tank 13 is not less than 2 mg / L. Water is discharged from the upper part of the second-stage aerobic tank 13. The effluent passes through a water collecting pipe with a slag retaining sleeve and is connected to the second-stage solid-liquid separation zone through a partition. The effluent flows into the second-stage solid-liquid separation zone by gravity.

[0059] The second-stage solid-liquid separation zone can be a vertical flow type with good sludge concentration effect. The bottom sludge collecting area is equipped with a sludge pump, a return sludge electric valve, and a sludge discharge electric valve. After the mud and water are separated in the second-stage solid-liquid separation zone, the clear water is collected by the water collecting weir and flows into the disinfection unit by gravity for disinfection and then discharged.

[0060] Example 2:

[0061] A dual-sludge return sewage treatment device for enhanced nitrogen and phosphorus removal includes an inlet pipe, a raw water tank 1, a sewage lifting pump 2, a water flow pipe assembly accessory system 3, a sewage treatment assembly unit, a sludge return and discharge unit 4, a supporting series of detection instruments, an outlet pipe, and a PLC controller module component in the equipment room. Sewage flows into the raw water tank 1 through the inlet pipe. The sewage lifting pump 2 is arranged in the raw water tank 1. The sewage lifting pump 2 and the water flow pipe assembly accessory system 3 lift the sewage in the raw water tank 1 and then flow it into the sewage treatment assembly unit and the two-stage solid-liquid separation area in sections. The sewage is treated, clarified, and disinfected to meet the standards before being discharged through the outlet pipe.

[0062] The water flow pipe assembly accessory system 3 includes water flow pipes and flow meters 5 and flow distribution regulating valves 6 installed on the water flow pipes at different locations. The flow meters 5 and flow distribution regulating valves 6 are connected to the equipment inter-device PLC controller module assembly through an electrical control circuit. The sewage treatment assembly unit includes a first-stage aerobic tank 7, which is equipped with a hanging cloth-type biological carrier 8 and an aeration facility.

[0063] The first-stage aerobic tank 7 is equipped with an oscillating device 9, which is connected to a hanging cloth-type biological carrier member 8 and can drive the hanging cloth-type biological carrier member 8 to vibrate horizontally and laterally. The hanging cloth-type biological carrier member 8 is equipped with biological fillers. The shaking of the hanging cloth-type biological carrier member 8 by the oscillating device 9 can prevent aged sludge from adhering to the surface of the biofilm, affecting the contact between aerobic bacteria and sewage and reducing the reaction efficiency. At the same time, the shaking of the hanging cloth-type biological carrier member 8 is conducive to the contact between aerobic bacteria and sewage, which can increase the nitrification reaction effect.

[0064] The present application is a double-sludge reflux sewage treatment device for enhanced denitrification and phosphorus removal, which can solve the problem of aged sludge and impurities adhered to the surface of the biological filler in the original sewage treatment equipment by means of the vibration of the cloth-hung biological carrier caused by the oscillation device, which is beneficial to the growth and renewal of the biofilm on the biological filler and realizes the double-sludge reflux to make the nitrification and phosphorus absorption reaction more thorough.

[0065] The sewage treatment combined unit further comprises a pre-denitrification tank 10, an anaerobic tank 11, a first-stage solid-liquid separation zone 27, an anoxic tank 12, a second-stage aerobic tank 13, and a second-stage solid-liquid separation zone 28, wherein the pre-denitrification tank 10, the anaerobic tank 11, the first-stage aerobic tank 7, the first-stage solid-liquid separation zone 27, the anoxic tank 12, the second-stage aerobic tank 13, the second-stage solid-liquid separation zone 28, and the equipment room are arranged in sequence from front to back on the entire sewage treatment device.

[0066] The sludge reflux and discharge unit 4 is arranged between the pre-denitrification tank 10, the first-stage solid-liquid separation zone 27, the anoxic tank 12, and the second-stage solid-liquid separation zone 28 through a sludge reflux and discharge pump and a pipeline.

[0067] The series of detection instruments include a dissolved oxygen detector, a redox potential detector, and a sludge concentration detector, and the anaerobic tank 11, the first-stage aerobic tank 7, and the second-stage aerobic tank 13 are respectively provided with a dissolved oxygen detector, the pre-denitrification tank 10, the anaerobic tank 11, and the anoxic tank 12 are respectively provided with a redox potential detector, and the pre-denitrification tank 10 and the anoxic tank 12 are respectively provided with a sludge concentration detector. The series of detection instruments are connected to the equipment room PLC controller module assembly through an electric control line, and the equipment room PLC controller module assembly and the series of detection instruments are connected to an external power supply through corresponding lines.

[0068] The sludge reflux and discharge unit 4 comprises a first-stage solid-liquid separation zone sludge reflux pipe group, a first-stage solid-liquid separation zone sludge discharge pipe group, a first-stage solid-liquid separation zone reflux sludge internal carbon source pipe group, a second-stage solid-liquid separation zone sludge reflux pipe group, and a second-stage solid-liquid separation zone sludge discharge pipe group.

[0069] The first-stage solid-liquid separation zone sludge reflux pipe group is provided with a pump and an electric valve, one end of the first-stage solid-liquid separation zone sludge reflux pipe group is connected to the first-stage solid-liquid separation zone 27 through the pump and the electric valve, and the other end is connected to the pre-denitrification tank 10, and the first-stage solid-liquid separation zone sludge reflux pipe group can reflux the sludge in the first-stage solid-liquid separation zone 27 into the pre-denitrification tank 10.

[0070] The carbon source pipe group in the return sludge of the first-stage solid-liquid separation zone is equipped with a pump (shared with the sludge return) and an electric valve. One end of the carbon source pipe group in the return sludge of the first-stage solid-liquid separation zone is connected to the first-stage solid-liquid separation zone 27 through the pump and the electric valve, and the other end is connected to the anoxic tank 12. The carbon source pipe group in the return sludge of the first-stage solid-liquid separation zone can return the carbon source in the return sludge of the first-stage solid-liquid separation zone to the anoxic tank 12.

[0071] The first-stage solid-liquid separation zone sludge discharge pipe group is installed at the bottom of the first-stage solid-liquid separation zone 27. The first-stage solid-liquid separation zone sludge discharge pipe group is equipped with a pump (shared with the sludge return) and an electric valve to discharge the sludge in the first-stage solid-liquid separation zone 27 to the outside;

[0072] The second-stage solid-liquid separation zone sludge return pipe group is equipped with a pump and an electric valve. One end of the second-stage solid-liquid separation zone sludge return pipe group is connected to the second-stage solid-liquid separation zone 28, and the other end is connected to the anoxic tank 12. The second-stage solid-liquid separation zone sludge return pipe group can return the sludge in the second-stage solid-liquid separation zone 28 to the anoxic tank 12;

[0073] The sludge discharge pipe group of the second-stage solid-liquid separation area is installed at the bottom of the second-stage solid-liquid separation area 28. The sludge discharge pipe group of the second-stage solid-liquid separation area is equipped with a pump (shared with the sludge reflux) and an electric valve, which can discharge the sludge in the second-stage solid-liquid separation area 28 to the outside.

[0074] The oscillation device 9 includes a cylinder assembly 14, a sliding support frame 15, a smooth inner rod 16, a support plate and a tendon buffer pad 17. The support plate is mounted on the edges of the left and right sides of the first-stage aerobic pool 7. Both ends of the smooth inner rod 16 are mounted on the support plate. The sliding support frame 15 is mounted on the smooth inner rod 16. One end of the sliding support frame 15 is connected to the cylinder assembly 14. The other end of the sliding support frame 15 is equipped with a tendon buffer pad 17. The cylinder assembly 14 can push the sliding support frame 15 to slide horizontally left and right on the smooth inner rod 16.

[0075] The sliding support frame 15 has a crossbeam 18, and the hanging cloth-type biological carrier member 8 can be a linear hanging cloth-type biological carrier member or a soft hanging cloth-type biological carrier member. The hanging cloth-type biological carrier member 8 is vertically hung on the crossbeam 18 of the sliding support frame 15, and the hanging cloth-type biological carrier member 8 can be loaded with biological fillers;

[0076] An L-shaped stirring rod 19 can also be provided on the sliding support frame 15. One end of the L-shaped stirring rod 19 is connected to the side of the sliding support frame 15. The other end of the L-shaped stirring rod 19 is provided with a brush head 20. The installation area of ​​the brush head 20 is located above the aeration head assembly in the aeration facility at the bottom of the first-stage aerobic tank 7. The L-shaped stirring rod 19 and the brush head 20 provided on the support rod can stir the sewage on the microporous aeration head 21, better clean the sludge on the microporous aeration head 21, and ensure its excellent aeration effect.

[0077] The aeration head assembly includes a microporous aeration head 21 and a sludge collecting member 22. The aeration head assembly is connected to the blower aeration equipment through an aeration pipe. A variable frequency flow distribution regulating valve is provided on the aeration pipe. The variable frequency flow distribution regulating valve is connected to the equipment inter-device PLC controller module assembly through an electric control circuit. The end of the aeration pipe is connected to the microporous aeration head 21. The sludge collecting member 22 is installed around the lower part of the microporous aeration head 21. The sludge collecting member 22 can collect or gather sludge and other debris settled on the microporous aeration head 21.

[0078] A soft curved film is provided on the top surface of the microporous aeration head 21. The soft curved film has aeration holes. When the frequency conversion flow distribution regulating valve is used to adjust the aeration volume delivered from the aeration pipeline to the microporous aeration head 21, the soft curved film on the microporous aeration head 21 can be shaken, thereby shaking off sludge and debris settled on the soft curved film in the microporous aeration head 21. These sludge and debris can fall into the sludge collecting piece 22.

[0079] Example 3:

[0080] Reference Figure 4-Figure 6 , based on Example 2, the difference is that: the water outlets of both the first-stage aerobic tank 7 and the second-stage aerobic tank 13 are provided with slag-blocking sleeve assemblies, the slag-blocking sleeve assembly comprises an outer sleeve 23, an inner sleeve 24 and an adapter member, the outer sleeve 23 is fixedly mounted on the outside of the inner sleeve 24 through a fixing bracket, the adapter member is mounted on the inner sleeve 24, and the inner sleeve 24 is equipped with a water outlet pipe 25 after passing through the slag block;

[0081] The bottom of the inner sleeve 24 is funnel-shaped, and the bottom end of the funnel-shaped inner sleeve 24 is connected to the water outlet pipe 25. The area between the outer sleeve 23 and the inner sleeve 24 is hollow except for the fixed bracket.

[0082] The design of the slag retaining sleeve can intercept scum, foam and other debris on the surface of the aerobic tank in the tank, and the sewage flows from the bottom of the outer sleeve into the inner sleeve and flows into the next process through the outlet pipe 25. This design can prevent scum, foam and other debris from flowing into the outlet pipe 25 and causing blockage, and can also prevent scum, foam and other debris from flowing into the next process and affecting the reaction efficiency.

[0083] Example 4:

[0084] Referring to Figure 5 Based on the embodiment 2, the difference is that the submersible stirring assembly is arranged in the pre-denitrification tank 10, the anaerobic tank 11 and the anoxic tank 12, the submersible stirring assembly comprises a support, a guide rod and a submersible stirrer 26, the support is arranged on the pre-denitrification tank 10, the anaerobic tank 11 and the anoxic tank 12, the guide rod is arranged on one side of the support, the submersible stirrer 26 is arranged on the other side of the guide rod, the support is provided with a U-shaped clamping groove, the orientation of the submersible stirrer 26 can be changed by rotating the guide rod in the U-shaped clamping groove;

[0085] The design can prevent the lateral aggregation of the substances in the pre-denitrification tank 10, the anaerobic tank 11 and the anoxic tank 12, so that the center of gravity of the whole double-sludge reflux sewage treatment device is unstable, and the lateral inclination or deflection occurs.

[0086] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical scheme and the concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A double sludge return sewage treatment device for enhanced nitrogen and phosphorus removal, comprising an inlet pipe, a raw water tank (1), a sewage lifting pump (2), a water flow pipe assembly accessory system (3), a sewage treatment assembly unit, a first-stage solid-liquid separation zone (27), a second-stage solid-liquid separation zone (28), a sludge return and discharge unit (4), a matching series of detection instruments, an outlet pipe, and a PLC controller module component between equipment. Sewage flows into the raw water tank (1) through the inlet pipe, the sewage lifting pump (2) is arranged in the raw water tank (1), the sewage lifting pump (2) and the water flow pipe assembly accessory system (3) lift the sewage in the raw water tank (1) and then enter the sewage treatment assembly unit in sections. The treated sewage is finally clarified in the second-stage solid-liquid separation zone (28) and is discharged through the outlet pipe after being disinfected to meet the standards. The water flow pipe assembly accessory system (3) comprises water flow pipes and flow meters (5) and flow distribution regulating valves (6) installed on the water flow pipes at different locations. The flow meters (5) and flow distribution regulating valves (6) are connected to the PLC controller module assembly between the equipment through an electric control circuit. The sewage treatment assembly unit comprises a first-stage aerobic tank (7), and the first-stage aerobic tank (7) is provided with a hanging cloth type biological carrier component (8) and an aeration facility. It is characterized in that The first-stage aerobic pool (7) is equipped with an oscillating device (9), which is connected to the hanging cloth-type biological carrier component (8) and can drive the hanging cloth-type biological carrier component (8) to vibrate horizontally and laterally.

2. A double sludge return sewage treatment device for enhanced denitrification and phosphorus removal according to claim 1, characterized in that: The sewage treatment combined unit further comprises a pre-denitrification tank (10), an anaerobic tank (11), a first-stage aerobic tank (7), a first-stage solid-liquid separation zone (27), an anoxic tank (12), a second-stage aerobic tank (13), and a second-stage solid-liquid separation zone (28), wherein the pre-denitrification tank (10), the anaerobic tank (11), the first-stage aerobic tank (7), the first-stage solid-liquid separation zone (27), the anoxic tank (12), the second-stage aerobic tank (13), the second-stage solid-liquid separation zone (28), and the equipment room are arranged in sequence from front to back on the entire sewage treatment device. The sludge return and discharge unit (4) is installed between the pre-denitrification tank (10), the first-stage solid-liquid separation zone (27), the anoxic tank (12), and the second-stage solid-liquid separation zone (28) through sludge return and discharge pumps and pipeline components. The supporting series of detection instruments include a dissolved oxygen detector, an oxidation-reduction potential detector and a sludge concentration detector. The anaerobic tank (11), the first-stage aerobic tank (7) and the second-stage aerobic tank (13) are respectively equipped with a dissolved oxygen detector. The pre-denitrification tank (10), the anaerobic tank (11) and the anoxic tank (12) are respectively equipped with an oxidation-reduction potential detector. The pre-denitrification tank (10) and the anoxic tank (12) are respectively equipped with a sludge concentration detector. The supporting series of detection instruments are connected to the equipment room PLC controller module assembly through an electric control circuit. The equipment room PLC controller module assembly and the supporting series of detection instruments are connected to the external power supply through corresponding circuits.

3. A double sludge return sewage treatment device for enhanced denitrification and phosphorus removal according to claim 2, characterized in that: The sludge return and discharge unit (4) comprises a first-stage solid-liquid separation zone sludge return pipe group, a first-stage solid-liquid separation zone sludge discharge pipe group, a first-stage solid-liquid separation zone sludge return carbon source pipe group, a second-stage solid-liquid separation zone sludge return pipe group and a second-stage solid-liquid separation zone sludge discharge pipe group. A pump and an electric valve are installed on the sludge return pipe group of the first-stage solid-liquid separation zone. One end of the sludge return pipe group of the first-stage solid-liquid separation zone is connected to the first-stage solid-liquid separation zone (27) through the pump and the electric valve, and the other end is connected to the pre-denitrification tank (10). The sludge return pipe group of the first-stage solid-liquid separation zone can return the sludge from the first-stage solid-liquid separation zone (27) to the pre-denitrification tank (10); A pump (shared with the sludge return) and an electric valve are installed on the carbon source pipe group of the return sludge in the first-stage solid-liquid separation zone. One end of the carbon source pipe group of the return sludge in the first-stage solid-liquid separation zone is connected to the first-stage solid-liquid separation zone (27) through the pump and the electric valve, and the other end is connected to the anoxic tank (12). The carbon source pipe group of the return sludge in the first-stage solid-liquid separation zone can return the carbon source in the return sludge in the first-stage solid-liquid separation zone to the anoxic tank (12); The first-stage solid-liquid separation zone sludge discharge pipe group is installed at the bottom of the first-stage solid-liquid separation zone (27). The first-stage solid-liquid separation zone sludge discharge pipe group is equipped with a pump (shared with the sludge return) and an electric valve, which can discharge the sludge in the first-stage solid-liquid separation zone (27) to the outside; A pump and an electric valve are installed on the second-stage solid-liquid separation zone sludge return pipe group. One end of the second-stage solid-liquid separation zone sludge return pipe group is connected to the second-stage solid-liquid separation zone (28), and the other end is connected to the anoxic tank (12). The second-stage solid-liquid separation zone sludge return pipe group can return the sludge in the second-stage solid-liquid separation zone (28) to the anoxic tank (12); The second-stage solid-liquid separation zone sludge discharge pipe group is installed at the bottom of the second-stage solid-liquid separation zone (28). The second-stage solid-liquid separation zone sludge discharge pipe group is equipped with a pump (shared with the sludge return) and an electric valve, which can discharge the sludge in the second-stage solid-liquid separation zone (28) to the outside.

4. A double sludge return sewage treatment device for enhanced denitrification and phosphorus removal according to claim 1, characterized in that: The oscillating device (9) comprises a cylinder assembly (14), a sliding support frame (15), a smooth inner-penetrating rod (16), a support plate and a tendon buffer pad (17). The support plate is mounted on the edges of the left and right sides of the first-stage aerobic pool (7). Both ends of the smooth inner-penetrating rod (16) are mounted on the support plate. The sliding support frame (15) is mounted on the smooth inner-penetrating rod (16). One end of the sliding support frame (15) is connected to the cylinder assembly (14). The other end of the sliding support frame (15) is equipped with a tendon buffer pad (17). The cylinder assembly (14) can push the sliding support frame (15) to slide horizontally on the smooth inner-penetrating rod (16).

5. A double sludge return sewage treatment device for enhanced denitrification and phosphorus removal according to claim 4, characterized in that: The sliding support frame (15) is provided with a crossbeam (18), and the cloth-hanging biological carrier component (8) can be a linear hanging biological carrier component or a soft cloth-hanging biological carrier component, and the cloth-hanging biological carrier component (8) is vertically hung on the crossbeam (18) of the sliding support frame (15).

6. A double sludge return sewage treatment device for enhanced denitrification and phosphorus removal according to claim 5, characterized in that: The sliding support frame (15) can also be provided with an L-shaped stirring rod (19), one end of which is connected to the side of the sliding support frame (15), and the other end of which is provided with a brush head (20), the installation area of ​​the brush head (20) being located above the aeration head assembly in the bottom aeration facility of the first-stage aerobic tank (7).

7. A double sludge return sewage treatment device for enhanced denitrification and phosphorus removal according to claim 6, characterized in that: The aeration head assembly comprises a microporous aeration head (21) and a sludge collecting part (22). The aeration head assembly is connected to the blower aeration equipment through an aeration pipe. A variable frequency flow distribution regulating valve is provided on the aeration pipe. The variable frequency flow distribution regulating valve is connected to the equipment inter-device PLC controller module assembly through an electric control circuit. The end of the aeration pipe is connected to the microporous aeration head (21). The sludge collecting part (22) is arranged around the lower part of the microporous aeration head (21). The sludge collecting part (22) can collect or gather sludge and other debris settled on the microporous aeration head (21).

8. A dual sludge return sewage treatment device for enhanced nitrogen and phosphorus removal according to claim 7, characterized in that: The upper top surface of the microporous aeration head (21) is provided with a soft curved film member, and the soft curved film member is provided with aeration through holes. When the aeration amount delivered by the aeration pipeline to the microporous aeration head (21) is adjusted to increase or decrease through the frequency conversion flow distribution regulating valve, the soft curved film member on the microporous aeration head (21) can be shaken, thereby shaking off the sludge and debris settled on the soft curved film member in the microporous aeration head (21), and the sludge and debris can fall into the sludge collecting member (22).

9. The dual sludge return sewage treatment device for enhanced denitrification and phosphorus removal according to claim 1, characterized in that: The first-stage aerobic tank (7) and the second-stage aerobic tank (13) are both provided with a slag-blocking sleeve assembly at their water outlets. The slag-blocking sleeve assembly comprises an adapter, an outer sleeve (23) and an inner sleeve (24). The outer sleeve (23) is fixedly mounted on the outside of the inner sleeve (24) through a fixing bracket. The adapter is mounted on the inner sleeve (24). The treated water from the first-stage aerobic tank (7) and the second-stage aerobic tank (13) flows in through the bottom of the outer sleeve (23) and then flows in from the top of the inner sleeve (24). The bottom of the inner sleeve (24) is provided with a water outlet pipe (25) after passing through the slag block.

10. A dual sludge return sewage treatment device for enhanced nitrogen and phosphorus removal according to claim 9, characterized in that: The bottom of the inner sleeve (24) is funnel-shaped, and the bottom end of the funnel-shaped inner sleeve (24) is connected to a water outlet pipe (25).

11. The dual sludge return sewage treatment device for enhanced nitrogen and phosphorus removal according to claim 1, characterized in that: The pre-denitrification tank (10), the anaerobic tank (11) and the anoxic tank (12) are all provided with a submersible stirring assembly, which comprises a bracket, a guide rod and a submersible stirrer (26). The bracket is installed on the pre-denitrification tank (10), the anaerobic tank (11) and the anoxic tank (12), one side of the guide rod is installed on the bracket, and the submersible stirrer (26) is installed on the other side of the guide rod. A U-shaped slot is provided on the bracket, and the direction of the submersible stirrer (26) can be changed by rotating the guide rod in the U-shaped slot.

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