Enhanced A2O process nitrogen and phosphorus removal system

Abstract

The utility model provides an enhanced A < 2 > O process nitrogen and phosphorus removal system which has relatively strong adaptive capacity to the C / N change of inlet water, and belongs to the technical field of sewage treatment. The system provided by the utility model comprises an anaerobic tank, a mid-sedimentation tank, a sulfur autotrophic denitrification filter tank, an aerobic tank and a final sedimentation tank which are sequentially communicated, and solves the problem that a treatment system in the prior art cannot meet the requirement of low C / N wastewater treatment. The system provided by the utility model has relatively strong adaptive capacity to the C / N change of inlet water, is relatively high in nitrogen and phosphorus removal efficiency, can effectively reduce the sludge yield, and is relatively low in operation energy consumption.

Description

Technical Field

[0001] The utility model relates to the technical field of sewage treatment, in particular to an enhanced A2O process denitrification and dephosphorization system. Background Art

[0002] A2O (also known as AAO method, Anaerobic-Anoxic-Oxic, anaerobic-anoxic-aerobic method) is a conventional process in the field of sewage treatment. This process mainly removes pollutants through the various functional bacteria in the activated sludge in various functional areas. However, in actual engineering, the treatment effect of the A2O process is often affected by the influent water quality. When the influent C / N is low, its nitrogen removal and phosphorus removal effects will be significantly limited, resulting in effluent exceeding the standard. Therefore, the A2O process is improved to adapt to various influent water qualities. The anaerobic ammonium oxidation process can directly convert NH4 + -N and NO2 - -N is converted into N2 to achieve autotrophic denitrification. Compared with the traditional denitrification process, the anaerobic ammonium oxidation process has the advantages of no need for external carbon source, low sludge production and small nitrogen oxide release. In addition, the anaerobic ammonium oxidation process has good treatment effect, low operating cost and small footprint. It has been recognized as one of the most economical biological denitrification processes. The sulfur autotrophic denitrification filter is also an autotrophic denitrification process. This process uses elemental sulfur instead of organic carbon source for autotrophic denitrification. It has the advantages of high denitrification rate, fast startup speed and low raw material cost. It is very suitable for improving the denitrification effect of low C / N sewage.

[0003] Chinese patent CN215799015U discloses a sewage treatment system based on an A2O reactor, comprising an A2O reactor and a vertical submerged flow artificial wetland, wherein the vertical submerged flow artificial wetland is located below the A2O reactor, and the primary treated water source obtained by the A2O reactor flows into the vertical submerged flow artificial wetland along the pipeline, and a hydraulic fan is provided on the pipeline, and the hydraulic fan is connected to the aeration pipe in the vertical submerged flow artificial wetland. The sewage treatment system has the advantages of good nitrogen and phosphorus removal effect and low operating cost.

[0004] However, in the treatment system of the prior art, there is competition between activated sludge and sulfur autotrophic denitrifying bacteria or anaerobic ammonia oxidizing bacteria, which is not conducive to the enrichment of related functional bacteria. In addition, the existing treatment system cannot meet the requirements of high C / N wastewater treatment, often causing raw water carbon source penetration and inhibition of aerobic nitrification, resulting in low raw water carbon source utilization and reduced nitrification effect. Summary of the invention

[0005] The utility model aims to provide an enhanced A2O process denitrification and phosphorus removal system, which has a strong adaptability to the C / N change of influent.

[0006] In order to achieve the above-mentioned invention object, the utility model provides the following technical solutions:

[0007] The utility model provides an enhanced A2O process denitrification and phosphorus removal system, which includes, in order of sewage treatment, from upstream to downstream:

[0008] Anaerobic tanks, used to synthesize PHA from organic matter in the sewage to be treated and release phosphate;

[0009] The intermediate sedimentation tank receives the intermediate product after the treatment in the anaerobic tank and is used for mud-water separation to obtain top supernatant and bottom sludge;

[0010] A sulfur autotrophic denitrification filter receives the top supernatant after treatment in the intermediate sedimentation tank, and is used for denitrification reaction and consumption of carbonate in limestone particles, and the generated calcium ions react with phosphate to produce calcium phosphate precipitation;

[0011] an aerobic tank, receiving the intermediate product after being treated by the sulfur autotrophic denitrification filter, for performing a short-range nitrification reaction and removing phosphate;

[0012] The final sedimentation tank receives the intermediate product after treatment in the aerobic tank and is used for mud-water separation to obtain top reflux liquid, treated water and bottom residual sludge.

[0013] Preferably, it further comprises a water inlet assembly and a water outlet assembly, wherein the water inlet assembly is connected to the anaerobic tank and is used to receive water to be treated;

[0014] The water outlet assembly is connected to the final sedimentation tank and is used to discharge treated water.

[0015] Preferably, a bypass pipeline is connected between the intermediate settling tank and the aerobic tank for discharging the bypass sludge at the bottom of the intermediate settling tank.

[0016] Preferably, it also includes a residual sludge pipeline, which is connected to the final sedimentation tank and is used to discharge the residual sludge.

[0017] Preferably, it also includes a first effluent return pipeline, wherein the first end of the first effluent return pipeline is arranged at the top of the final settling tank, and the second end of the first effluent return pipeline is arranged at the bottom of the sulfur autotrophic denitrification filter tank for discharging the reflux liquid at the top of the final settling tank.

[0018] Preferably, it also includes a second effluent return pipeline, the first end of which is arranged at the bottom of the final settling tank, and the second end of which is arranged at the front end of the anaerobic tank for discharging the return sludge at the bottom of the final settling tank.

[0019] Preferably, an agitator is provided at the bottom of the anaerobic tank.

[0020] Preferably, an aerator is provided at the bottom of the aerobic tank.

[0021] Beneficial effects of the utility model:

[0022] The enhanced A2O process denitrification and phosphorus removal system provided by the utility model has a strong adaptability to the change of influent C / N. When the influent C / N is high, the sulfur autotrophic denitrification filter mainly performs anaerobic ammonia oxidation and heterotrophic denitrification, while when the C / N is low, the sulfur autotrophic denitrification filter mainly performs anaerobic ammonia oxidation and sulfur autotrophic denitrification. The utility model utilizes sulfur autotrophic denitrification and anaerobic ammonia oxidation to make up for the problem of insufficient carbon source of raw water and low efficiency of denitrification and phosphorus removal. The raw water carbon source is mainly used for phosphorus removal. At the same time, the calcium ions generated by the sulfur autotrophic denitrification filter in the utility model can be used for chemical phosphorus removal, thereby realizing efficient denitrification and phosphorus removal. Since sulfur autotrophic denitrifying bacteria and anaerobic ammonia oxidizing bacteria are both autotrophic bacteria, they use inorganic carbon for growth and have a slow growth rate, which can effectively reduce sludge production. The enhanced A2O process denitrification and phosphorus removal system provided by the utility model also has the advantage of low operating energy consumption, because the aerobic tank therein only needs to perform short-range nitrification, and anaerobic ammonia oxidation can remove part of the ammonia nitrogen, thus saving a lot of aeration energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The schematic diagram of the structure of the enhanced A2O process denitrification and phosphorus removal system provided by the utility model, wherein: 1-water inlet pipeline; 201-anaerobic tank; 202-intermediate sedimentation tank; 203-sulfur autotrophic denitrification filter; 204-aerobic tank; 205-surpassing sludge pipeline; 206-effluent return pipeline; 207-sludge return pipeline; 208-agitator; 209-aerator; 3-final sedimentation tank; 301-effluent pipeline; 302-residual sludge pipeline. DETAILED DESCRIPTION

[0024] In the utility model, using Figure 1 The enhanced A2O process denitrification and phosphorus removal system shown in the figure is used for wastewater treatment, preferably including the following steps:

[0025] The sewage to be treated first enters the anaerobic tank through the water inlet pipe, and part of the activated sludge in the final sedimentation tank is returned to the anaerobic tank; the polyphosphate bacteria in the activated sludge synthesize PHA using organic matter in the water and release phosphate;

[0026] The effluent from the anaerobic tank enters the intermediate sedimentation tank for mud-water separation; the top supernatant enters the sulfur autotrophic denitrification filter, and the bottom sludge enters the aerobic tank through the surpassing sludge pipeline; the surpassing ratio of the bottom sludge of the intermediate sedimentation tank is preferably in the range of 10% to 50%;

[0027] The effluent from the intermediate sedimentation tank and the effluent from the final sedimentation tank enter the sulfur autotrophic denitrification filter together for denitrification reaction; the anaerobic ammonia oxidizing bacteria on the biofilm of the sulfur autotrophic denitrification filter can remove NH4 + -N and NO2 in effluent reflux - -N, and produces a small amount of NO3 - -N; At the same time, the heterotrophic denitrifying bacteria on the biofilm at the bottom of the sulfur autotrophic denitrification filter use the organic matter in the sewage for heterotrophic denitrification, and the sulfur autotrophic denitrifying bacteria on the top biofilm use sulfur particles for autotrophic denitrification. The denitrifying bacteria and sulfur autotrophic denitrifying bacteria neutralize the NO3 produced by anaerobic ammonia oxidation in the effluent return liquid. - -N is reduced to N2; in addition, sulfur autotrophic denitrification consumes carbonate in limestone, and the generated calcium ions react with phosphate to produce calcium phosphate precipitation; the filler in the sulfur autotrophic denitrification filter is a mixture of granular sulfur and marble, the volume ratio of sulfur to limestone is preferably 1:1-3, and the particle size is preferably 2-5 mm; the biofilm of the sulfur autotrophic denitrification filter contains sulfur autotrophic denitrifying bacteria and anaerobic ammonia oxidizing bacteria, wherein the anaerobic ammonia oxidizing bacteria comes from the sludge inoculated with anaerobic ammonia oxidizing bacteria, and the sulfur autotrophic denitrifying bacteria grows by in situ enrichment, and the biofilm concentration is preferably >300 mg / L; the culture source of the anaerobic ammonia oxidizing bacteria is concentrated sludge from a municipal sewage treatment plant, the sludge concentration is diluted to 3000-6000 mg / L, and the culture solution is prepared with original tap water or well water, wherein the concentrations of ammonia nitrogen and nitrite are both 50-100 mg / L. The culture method of continuous water inflow is adopted, the hydraulic retention time is 8 to 16 hours, the culture temperature is 30 to 35°C, and the culture is considered successful when the total nitrogen removal rate is higher than 80% for 5 consecutive days.

[0028] The effluent from the sulfur autotrophic denitrification filter enters the aerobic tank; the ammonia oxidizing bacteria in the activated sludge of the aerobic tank undergo a short-range nitrification reaction to convert NH4 + -N is oxidized to NO2 - -N, aerobic pool effluent NH4 + -N is preferably <1.0mg / L, and NO2 - -N accumulation rate is preferably greater than 60%; at the same time, polyphosphate bacteria in the activated sludge absorb excessive phosphorus to complete phosphate removal; the DO of the aerobic pool is preferably controlled at 0.5-2 mg / L;

[0029] The activated sludge in the system of the utility model is taken from the concentrated sludge of the municipal sewage treatment plant, and the sludge concentration is preferably 3000-6000 mg / L;

[0030] The effluent from the aerobic tank enters the final sedimentation tank for mud-water separation; the effluent from the top of the final sedimentation tank flows back to the sulfur autotrophic denitrification filter, and the remaining effluent is discharged from the system; the activated sludge from the bottom flows back to the anaerobic tank, and the remaining sludge is discharged from the system through the remaining activated sludge pipeline; the reflux ratio of the effluent return liquid from the final sedimentation tank is preferably in the range of 100% to 300%, and the reflux ratio of the return sludge is preferably in the range of 50% to 100%, and the discharge amount of the remaining sludge in the final sedimentation tank is adjusted to preferably control the SRT of the activated sludge to 15 to 30 days;

[0031] In the above steps, the HRT of the anaerobic tank is preferably 1-2h, the HRT of the intermediate sedimentation tank is preferably 2-4h, the HRT of the sulfur autotrophic denitrification filter is preferably 1-3h, the HRT of the aerobic tank is preferably 2-4h, and the HRT of the final sedimentation tank is preferably 1-3h.

[0032] The technical solutions provided by the present utility model are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the protection scope of the present utility model.

[0033] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Example 1

[0036] Figure 1 The schematic diagram of the structure of the enhanced A2O process denitrification and phosphorus removal system provided by the utility model is as follows: Figure 1As shown, the enhanced A2O process denitrification and phosphorus removal system provided by the utility model includes: 1-water inlet pipeline; 201-anaerobic tank; 202-intermediate sedimentation tank; 203-sulfur autotrophic denitrification filter; 204-aerobic tank; 205-surpassing sludge pipeline; 206-effluent return pipeline; 207-sludge return pipeline; 208-agitator; 209-aerator; 3-final sedimentation tank; 301-effluent pipeline; 302-residual sludge pipeline.

[0037] The enhanced A2O process denitrification and phosphorus removal system structure provided by the utility model comprises a reaction tank, an inlet pipeline (1) and an outlet pipeline (301) in sequence, wherein the reaction tank comprises an anaerobic tank (201), a medium sedimentation tank (202), a sulfur autotrophic denitrification filter (203), an aerobic tank (204), and a final sedimentation tank (3); the inlet pipeline is connected to the anaerobic tank, and the outlet pipeline is connected to the final sedimentation tank. The water to be treated enters from the inlet pipeline, passes through the anaerobic tank, the medium sedimentation tank, the sulfur autotrophic denitrification filter, the aerobic tank, and the final sedimentation tank in sequence, and is discharged through the outlet pipeline. The residual sludge in the final sedimentation tank is discharged through the residual sludge pipeline (302).

[0038] An overrunning pipeline (205) is provided between the intermediate settling tank and the aerobic tank, and the overrunning sludge flows from the bottom of the intermediate settling tank to the front end of the aerobic tank; an effluent return pipeline (206) is provided between the final settling tank and the sulfur autotrophic denitrification filter, and the return liquid flows from the top of the final settling tank to the bottom of the sulfur autotrophic denitrification filter; a sludge return pipeline (207) is provided between the final settling tank and the anaerobic tank, and the return sludge flows from the bottom of the final settling tank to the front end of the anaerobic tank; a stirrer (208) is provided at the bottom of the anaerobic tank; and an aerator (209) is provided at the bottom of the aerobic tank.

[0039] In the utility model, first, the polyphosphate bacteria in the anaerobic tank utilizes the carbon source in the influent to release phosphorus, releasing phosphate into the sewage. Then, the effluent from the anaerobic tank is separated from mud and water in the middle sedimentation tank, and the water enters the sulfur autotrophic denitrification filter for autotrophic denitrification, and the calcium ions dissolved from the marble in the sulfur autotrophic denitrification filter also have a partial dephosphorization effect; in addition, the mud in the middle sedimentation tank enters the aerobic tank. Subsequently, the water from the sulfur autotrophic denitrification filter and the mud from the middle sedimentation tank enter the aerobic tank together to carry out short-range nitrification reaction and excessive phosphorus absorption reaction of polyphosphate bacteria. Finally, it enters the final sedimentation tank for mud and water separation; in the present invention, the sulfur autotrophic denitrification filter is connected to the aerobic tank and the anaerobic tank. First, it is connected to the aerobic tank, and through the reflux of the effluent from the secondary sedimentation tank, the NO2-N produced by the aerobic tank is used to carry out anaerobic ammonia oxidation and sulfur autotrophic denitrification reaction to achieve autotrophic denitrification. Then there is the connection with the anaerobic tank. The effluent ammonia nitrogen of the anaerobic tank can be used for anaerobic ammonia oxidation, and the released phosphate can be used for chemical phosphorus removal, which can also reduce the phosphorus removal pressure of the aerobic tank. However, since the sulfur autotrophic denitrification filter is easily blocked by activated sludge, it is necessary to add a sedimentation tank between the anaerobic tank and the sulfur autotrophic denitrification filter. The mud and water are separated in the middle sedimentation tank, and the effluent enters the sulfur autotrophic denitrification filter, and the sedimented and concentrated bottom mud enters the aerobic tank. There are two main purposes of setting it up. One is to reduce the SS of the influent of the sulfur autotrophic denitrification filter, and the other is to minimize the influent to the aerobic tank while ensuring the sludge concentration of the influent of the aerobic tank, so as to avoid a large influent, resulting in excessive ammonia nitrogen in the influent of the aerobic tank, and causing the total nitrogen in the effluent to exceed the standard.

[0040] Use the above system to treat high influent C / N sewage:

[0041] The sewage used in this example is the influent of a sewage plant in Beijing. The average influent COD and NH4 + -N, TN and TP are 284.33, 43.81, 45.16 and 8.12 mg / L respectively, and the inlet C / N reaches 6.3. The inlet flow rate is 200m 3 / d, the hydraulic retention time of the anaerobic tank, the intermediate sedimentation tank, the sulfur autotrophic denitrification filter, the aerobic tank, and the final sedimentation tank are 2, 2.5, 2, 3.5, and 1.5h, respectively, for a total of 11.5h. The exceedance ratio of the intermediate sedimentation tank is 15%, the effluent return ratio of the final sedimentation tank is 200%, and the sludge return ratio is 70%. The dissolved oxygen in the aerobic tank is controlled at 1.0-1.5mg / L, and the sludge retention time of the A / O process is controlled at 20 days. The volume ratio of sulfur to limestone in the sulfur autotrophic denitrification filter is 1:1.5, and the particle size of sulfur particles and limestone particles is 2-5mm. After stable operation, the nitrogen and phosphorus removal effect of the system is stable, and the effluent TN and TP can be reduced to about 9.29mg / L and 0.17mg / L, respectively. The inlet and outlet water quality is shown in Table 1.

[0042] Table 1 Inlet and outlet water quality (high inlet C / N)

[0043] CODcr <![CDATA[NH4 + -N]]> TN TP Water Intake 284.33±13.37 43.81±2.28 45.16±2.22 8.12±0.27 Water 29.40±0.54 0.22±0.14 9.29±0.40 0.17±0.05

[0044] Example 2

[0045] The system is the same as Example 1, and conventional influent C / N sewage treatment is performed:

[0046] The sewage used in this example is the influent of a sewage plant in Beijing. The average influent COD and NH4 + -N, TN and TP are 206.57, 48.48, 49.68 and 7.82 mg / L respectively, and the inlet C / N is about 4.16. The inlet flow rate is 500m 3 / d, the hydraulic retention time of the anaerobic tank, the intermediate sedimentation tank, the sulfur autotrophic denitrification filter, the aerobic tank, and the final sedimentation tank are 1.5, 2, 1.5, 4, and 1.5 hours, respectively, for a total of 10.5 hours. The overflow ratio of the intermediate sedimentation tank is 25%, the effluent return ratio of the final sedimentation tank is 250%, and the sludge return ratio is 50%. The dissolved oxygen in the aerobic tank is controlled at 1.0-1.5 mg / L, and the sludge retention time of the A / O process is controlled at 20 days. The volume ratio of sulfur to limestone in the sulfur autotrophic denitrification filter is 1:2, and the particle size of sulfur particles and limestone particles is 2-5 mm. After stable operation, the nitrous acid accumulation rate of the aerobic tank of the system reaches 80%, the effluent TN and TP can be reduced to below 10 and 0.5 mg / L respectively, and the removal rates reach 80% and above 90% respectively, achieving efficient nitrogen and phosphorus removal. At the same time, the denitrification contribution rate of sulfur autotrophic denitrification filter reached 68.92%, of which anaerobic ammonium oxidation accounted for 29.32%. The water quality of inlet and outlet water is shown in Table 2.

[0047] Table 2 Inlet and outlet water quality (normal inlet C / N)

[0048] CODcr <![CDATA[NH4 + -N]]> TN TP Water Intake 206.57±5.77 48.48±0.90 49.68±1.01 7.82±0.31 Water 28.32±1.02 0.15±0.14 9.43±0.23 0.18±0.08

[0049] Example 3

[0050] The system is the same as Example 1, and low influent C / N sewage treatment is performed:

[0051] The sewage used in this example is the influent of a sewage plant in Beijing. The average influent COD and NH4 + -N, TN and TP are 114.58, 41.00, 42.16 and 7.29 mg / L respectively, and the inlet C / N is about 2.72. The inlet flow rate is 300m 3 / d, the hydraulic retention time of the anaerobic tank, the intermediate sedimentation tank, the sulfur autotrophic denitrification filter, the aerobic tank, and the final sedimentation tank are 1.5, 2.5, 2, 3, and 2 hours, respectively, for a total of 11 hours. The excess ratio of the intermediate sedimentation tank is 30%, the effluent return ratio of the final sedimentation tank is 300%, and the sludge return ratio is 50%. The dissolved oxygen in the aerobic tank is controlled at 0.5-1.0 mg / L, and the sludge retention time of the A / O process is controlled at 25 days. The volume ratio of sulfur to limestone in the sulfur autotrophic denitrification filter is 1:2.5, and the particle size of sulfur particles and limestone particles is 2-5 mm. After stable operation, the nitrous acid accumulation rate of the aerobic tank of the system reached more than 80%, and the effluent TN and TP were stably reduced to about 6.71 and 0.22 mg / L, respectively. At the same time, the denitrification contribution rate of the sulfur autotrophic denitrification filter reached 74.01%, of which anaerobic ammonia oxidation accounted for 41.08%, achieving efficient autotrophic denitrification. The inlet and outlet water qualities are shown in Table 3.

[0052] Table 3 Inlet and outlet water quality (low inlet C / N)

[0053] CODcr <![CDATA[NH4 + -N]]> TN TP Water Intake 114.58±10.00 41.00±2.22 42.16±2.04 7.29±0.35 Water 27.30±1.53 0.16±0.14 6.71±0.51 0.22±0.07

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An enhanced A2O process denitrification and phosphorus removal system, characterized in that: In the order of sewage treatment, from upstream to downstream, it includes: Anaerobic tanks, used to synthesize PHA from organic matter in the sewage to be treated and release phosphate; The intermediate sedimentation tank receives the intermediate product after the treatment in the anaerobic tank and is used for mud-water separation to obtain top supernatant and bottom sludge; A sulfur autotrophic denitrification filter receives the top supernatant after treatment in the intermediate sedimentation tank, and is used for denitrification reaction and consumption of carbonate in limestone particles, and the generated calcium ions react with phosphate to produce calcium phosphate precipitation; an aerobic tank, receiving the intermediate product after the sulfur autotrophic denitrification filter is treated, and used for short-range nitrification reaction and phosphate removal; The final sedimentation tank receives the intermediate product after treatment in the aerobic tank and is used for mud-water separation to obtain top reflux liquid, treated water and bottom residual sludge.

2. The enhanced A2O process denitrification and phosphorus removal system according to claim 1 is characterized in that: It also includes a water inlet assembly and a water outlet assembly, wherein the water inlet assembly is connected to the anaerobic tank and is used to receive water to be treated; The water outlet assembly is connected to the final sedimentation tank and is used to discharge treated water.

3. The enhanced A2O process denitrification and phosphorus removal system according to claim 1, characterized in that: A bypass pipeline is connected between the intermediate sedimentation tank and the aerobic tank, and is used for discharging the bypass sludge at the bottom of the intermediate sedimentation tank.

4. The enhanced A2O process denitrification and phosphorus removal system according to claim 1, characterized in that: It also includes a residual sludge pipeline, which is connected to the final sedimentation tank and is used to discharge the residual sludge.

5. The enhanced A2O process denitrification and phosphorus removal system according to claim 1, characterized in that: It also includes a first effluent return pipeline, a first end of which is arranged at the top of the final settling tank, and a second end of which is arranged at the bottom of the sulfur autotrophic denitrification filter tank for discharging the return liquid at the top of the final settling tank.

6. The enhanced A2O process denitrification and phosphorus removal system according to claim 1, characterized in that: It also includes a second effluent return pipeline, a first end of which is arranged at the bottom of the final settling tank, and a second end of which is arranged at the front end of the anaerobic tank for discharging return sludge at the bottom of the final settling tank.

7. The enhanced A2O process denitrification and phosphorus removal system according to claim 1, characterized in that: A stirrer is arranged at the bottom of the anaerobic tank.

8. The enhanced A2O process denitrification and phosphorus removal system according to claim 1, characterized in that: An aerator is arranged at the bottom of the aerobic pool.

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