Nitrogen and phosphorus removal system and treatment method for rural domestic sewage

Abstract

The invention relates to a nitrogen and phosphorus removal system for rural domestic sewage. The nitrogen and phosphorus removal system comprises an adjusting tank, a first treatment assembly, a second treatment assembly, an aeration assembly and a denitrification ecological filter tank, the adjusting tank is respectively connected with the first treatment assembly and the second treatment assembly, the first treatment assembly is communicated with the second treatment assembly, and the second treatment assembly is connected with the denitrification ecological filter tank; the aeration assembly is respectively communicated with the first treatment assembly and the second treatment assembly. The nitrogen and phosphorus removal system and the treatment method for the rural domestic sewage are provided for overcoming the defects in the prior art, the nitrogen and phosphorus removal effect is good, the treatment cost is low, the operation stability is high, meanwhile, maintenance is easy, and mounting and dismounting are convenient.

Description

Technical Field

[0001] The invention relates to a denitrification and dephosphorization system for rural domestic sewage and a treatment method. Background Art

[0002] Rural domestic sewage mainly refers to the sewage generated by rural residents in their daily lives, including kitchen water (such as wastewater from washing vegetables, rice, and dishes), laundry water, bathing water, and toilet sewage, etc. The composition of these sewage is relatively complex, including organic matter (such as food residues, grease, detergents, etc.), nutrients such as nitrogen and phosphorus, microorganisms, and suspended matter.

[0003] As the country pays more and more attention to the "three rural issues", the requirement of building a new type of ecological civilization has been put forward. However, the situation of rural domestic sewage treatment is still not optimistic. The water quality and water volume of rural domestic sewage vary greatly, and the C / N ratio (carbon-nitrogen ratio) is low. These characteristics make it difficult to remove nitrogen and phosphorus from rural domestic sewage, and it is difficult to meet the effluent water quality standards.

[0004] Therefore, in view of the above problems, a denitrification and phosphorus removal system and treatment method for rural domestic sewage is proposed. Summary of the invention

[0005] The purpose of the present invention is to overcome the existing technical defects and provide a denitrification and phosphorus removal system and treatment method for rural domestic sewage, which has good denitrification and phosphorus removal effects, low treatment costs, high operating stability, simple maintenance, and is easy to install and disassemble.

[0006] The technical scheme for achieving the above object is: a rural domestic sewage denitrification and phosphorus removal system, comprising a regulating tank, a first treatment component, a second treatment component, an aeration component and a denitrification ecological filter tank;

[0007] The regulating tank is connected to the first treatment component and the second treatment component respectively, the first treatment component is connected to the second treatment component, and the second treatment component is connected to the denitrification ecological filter; the aeration component is connected to the first treatment component and the second treatment component respectively.

[0008] Preferably, the first treatment component includes an anaerobic reactor, a first contact oxidation reactor and a second contact oxidation reactor; the inlet of the anaerobic reactor is connected to the regulating tank through a first pipeline, the outlet of the anaerobic reactor is connected to the first contact oxidation reactor through a third pipeline, the outlet of the first contact oxidation reactor is connected to the inlet of the second contact oxidation reactor through a fourth pipeline; the outlet of the second contact oxidation reactor is connected to the second treatment component through a fifth pipeline;

[0009] The first pipeline is connected to a first sewage pump.

[0010] Preferably, the second treatment component includes a denitrification reactor and a third contact oxidation reactor; the inlet of the denitrification reactor is connected to the second pipeline, and the other end of the second pipeline is connected to the regulating tank; the outlet of the denitrification reactor is connected to the inlet of the third contact oxidation reactor through a sixth pipeline, and the outlet of the third contact oxidation reactor is connected to the denitrification ecological filter through a seventh pipeline;

[0011] The second pipeline is connected to a second sewage pump.

[0012] Preferably, the aeration assembly includes an aeration main pipe, one end of which is connected to an air pump, the first contact oxidation reactor and the second contact oxidation reactor are each connected to the aeration main pipe through a first aeration pipe; and the third contact oxidation reactor is connected to the aeration main pipe through a second aeration pipe.

[0013] Preferably, a solar photovoltaic panel is arranged on the regulating pool, and the solar photovoltaic panel is respectively connected to a heating switch and an air pump switch through a solar controller, the other end of the heating switch is connected to a heater, and the other end of the air pump switch is connected to the air pump; the heater is located in the regulating pool.

[0014] Preferably, the anaerobic reactor, the first contact oxidation reactor, the second contact oxidation reactor, the denitrification reactor and the third contact oxidation reactor are all provided with an upper cover plate at the upper end and a circular bottom at the lower end; fillers are provided inside, and a water-permeable plate is provided inside, and a plurality of water-permeable holes are provided on the water-permeable plate.

[0015] Preferably, the denitrification ecological filter is connected to the seventh pipeline through the filter inlet pipe and discharged through the filter outlet pipe; a pebble layer is arranged on the bottom surface of the filter inlet pipe, a zeolite layer is arranged above the pebble layer, a pyrite / pebble layer is arranged above the zeolite layer, a melon seed layer is arranged above the pyrite / pebble layer, and canna and iris are arranged above the melon seed layer.

[0016] A method for treating a rural domestic sewage denitrification and dephosphorization system comprises the following steps:

[0017] Step 1: Rural domestic sewage is pumped into the anaerobic reactor by a sewage pump after passing through a regulating tank. After the sewage undergoes anaerobic reaction for 2-6 hours, the anaerobic reactor enters the first contact oxidation reactor and the second contact oxidation reactor in turn through the liquid level difference. They stay for 4-8 hours for contact oxidation reaction respectively and then enter the denitrification reactor through the liquid level difference.

[0018] Step 2: At the same time, the sewage pump pumps the sewage entering the regulating tank into the denitrification reactor at a ratio of 10-30%. After the sewage undergoes denitrification reaction for 2-6 hours, it enters the third contact oxidation reactor through the liquid level difference. After staying in the third contact oxidation reactor for 4-8 hours, it enters the denitrification ecological filter tank. After 6-10 hours of reaction, the effluent meets the discharge standards.

[0019] The beneficial effects of the present invention are as follows: the denitrification and phosphorus removal system and treatment method for rural domestic sewage treats rural domestic sewage by arranging a regulating tank, an anaerobic reactor, a first contact oxidation reactor, a second contact oxidation reactor, a denitrification reactor, a third contact oxidation reactor and a denitrification ecological filter. When the sewage passes through the above-mentioned tank bodies, the different microorganisms on the biological fillers can better remove pollutants such as COD, ammonia nitrogen, total phosphorus, total nitrogen in the sewage, especially the treatment effect on total phosphorus and total nitrogen is better, and each tank body is independent of each other and can be combined or disassembled, so as to adapt to different rural environments.

[0020] The secondary contact oxidation reactor and raw sewage are introduced into the denitrification reactor together, so that the microorganisms use the organic matter in the raw sewage as a carbon source to carry out denitrification reaction, remove nitrates in the sewage, and improve the denitrification and nitrogen removal capacity of the traditional AAO system.

[0021] Solar photovoltaic panels are installed, connected to an air pump and a heater in the regulating tank. On the one hand, solar energy can be used to heat up the sewage and improve the ability of microorganisms to remove pollutants, especially in winter when the temperature is low, which can greatly improve the removal effect of pollutants. On the other hand, solar energy can be converted into electrical energy to aerate the contact oxidation reactor through an air pump, thereby reducing the cost of sewage treatment.

[0022] The pyrite filler used in the denitrification ecological filter can produce a large amount of sulfur and iron ions that can serve as electron donors. Autotrophic denitrification reaction can occur without the need to add a carbon source, thereby enhancing the denitrification effect. In addition, pyrite can produce free iron ions, which can form iron phosphate precipitates with phosphates. Coupled with the adsorption and filtration effects of the zeolite filler, the removal effect of total phosphorus pollutants can be greatly improved, thereby achieving the purpose of efficient denitrification and phosphorus removal in sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a connection schematic diagram of the denitrification and phosphorus removal system for rural domestic sewage of the present invention;

[0024] Figure 2 is a schematic diagram of an anaerobic reactor of the present invention;

[0025] Figure 3 It is a detailed view of the water-permeable plate of the present invention;

[0026] Figure 4It is a detailed diagram of the denitrification ecological filter tank of the present invention.

[0027] In the figure: 1. regulating tank; 2. solar photovoltaic panel; 3. heater; 4. heating switch; 5. air pump; 6. first sewage pump; 7. air pump switch; 8. first pipeline; 9. anaerobic reactor; 10. first contact oxidation reactor; 11. second contact oxidation reactor; 12. denitrification reactor; 13. third contact oxidation reactor; 14. denitrification ecological filter; 15. valve; 16. upper cover plate; 17. filler; 18. permeable plate; 20. Arc bottom; 22. Water-permeable hole; 23. Second pipeline; 24. Filter inlet pipe; 25. Canna and iris; 26. Melon seed layer; 27. Pyrite / pebble layer; 28. Zeolite layer; 29. ​​Pebble layer; 30. Filter outlet pipe; 31. Third pipeline; 32. Fourth pipeline; 33. Fifth pipeline; 34. Sixth pipeline; 35. Seventh pipeline; 36. Aeration main pipeline; 37. First aeration pipeline; 38. Second aeration pipeline. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on 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.

[0029] The present invention will be further described below in conjunction with the accompanying drawings.

[0030] like Figure 1-4 As shown, a denitrification and phosphorus removal system for rural domestic sewage includes a regulating tank 1, a first treatment component, a second treatment component, an aeration component and a denitrification ecological filter 14; the regulating tank 1 is connected to the first treatment component and the second treatment component respectively, the first treatment component is connected to the second treatment component, and the second treatment component is connected to the denitrification ecological filter 14; the aeration component is connected to the first treatment component and the second treatment component respectively.

[0031] Specifically, the first treatment component includes an anaerobic reactor 9, a first contact oxidation reactor 10 and a second contact oxidation reactor 11; the inlet of the anaerobic reactor 9 is connected to the regulating tank 1 through a first pipeline 8, the outlet of the anaerobic reactor 9 is connected to the first contact oxidation reactor 10 through a third pipeline 31, the outlet of the first contact oxidation reactor 10 is connected to the inlet of the second contact oxidation reactor 11 through a fourth pipeline 32, and the outlet of the second contact oxidation reactor 11 is connected to the second treatment component through a fifth pipeline 33; the first sewage pump 6 is connected to the first pipeline 8. A valve 15 is also provided on the first pipeline 8.

[0032] Specifically, the second treatment component includes a denitrification reactor 12 and a third contact oxidation reactor 13; the inlet of the denitrification reactor 12 is connected to the second pipeline 23, and the other end of the second pipeline 23 is connected to the regulating tank 1; the outlet of the denitrification reactor 12 is connected to the inlet of the third contact oxidation reactor 13 through the sixth pipeline 34, and the outlet of the third contact oxidation reactor 13 is connected to the denitrification ecological filter 14 through the seventh pipeline 35; the second pipeline 23 is connected to a second sewage pump.

[0033] Specifically, the aeration assembly includes an aeration main pipe 36, one end of which is connected to the air pump 5, the first contact oxidation reactor 10 and the second contact oxidation reactor 11 are each connected to the aeration main pipe 36 through a first aeration pipe 37; the third contact oxidation reactor 13 is connected to the aeration main pipe 36 through a second aeration pipe 38.

[0034] Specifically, a solar photovoltaic panel 2 is arranged on the regulating tank 1, and the solar photovoltaic panel 2 is respectively connected to a heating switch 4 and an air pump switch 7 through a solar controller, the other end of the heating switch 4 is connected to a heater 3, and the other end of the air pump switch 7 is connected to an air pump 5; the heater 3 is located in the regulating tank 1.

[0035] Specifically, a solar photovoltaic panel 2 is installed above the regulating tank 1. After the collected solar energy is converted into electrical energy, the sewage can be heated by a heater 3 in cold weather to improve the ability of microorganisms in the reactor to remove pollutants. At the same time, an air pump 5 is used to aerate the contact oxidation reactor, thereby reducing the cost of sewage treatment.

[0036] Specifically, the anaerobic reactor 9, the first contact oxidation reactor 10, the second contact oxidation reactor 11, the denitrification reactor 12 and the third contact oxidation reactor 13 are all provided with an upper cover plate 16 at the upper end and a circular arc bottom 20 at the lower end; a filler 17 is provided inside, and a water-permeable plate 18 is provided inside, and a plurality of water-permeable holes 22 are provided on the water-permeable plate 18.

[0037] Specifically, the anaerobic reactor 9, the first contact oxidation reactor 10, the second contact oxidation reactor 11, the denitrification reactor 12 and the third contact oxidation reactor 13 are all configured in a cylindrical shape, and are all provided with exhaust valves on the top.

[0038] Specifically, the water flow direction is controlled by height difference among the anaerobic reactor 9, the first contact oxidation reactor 10, the second contact oxidation reactor 11, the denitrification reactor 12 and the third contact oxidation reactor 13, and the water head height difference is controlled to be 20-30 cm.

[0039] Specifically, the interiors of the anaerobic reactor 9, the first contact oxidation reactor 10, the second contact oxidation reactor 11, the denitrification reactor 12 and the third contact oxidation reactor 13 are all filled with polyurethane sponge cube fillers, and the filling ratio is 30-50%.

[0040] Specifically, the denitrification ecological filter 14 is connected to the seventh pipeline 35 through the filter inlet pipe 24 and discharged through the filter outlet pipe 30; a pebble layer 29 is arranged on the bottom surface of the filter inlet pipe 24, a zeolite layer 28 is arranged above the pebble layer 29, a pyrite / pebble layer 27 is arranged above the zeolite layer 28, a melon seed layer 26 is arranged above the pyrite / pebble layer 27, and canna and iris 25 are arranged above the melon seed layer 26.

[0041] Specifically, the denitrification ecological filter 14 contains a pyrite / pebble layer 27, which can produce a large amount of sulfur and iron ions that can serve as electron donors. Autotrophic denitrification reaction can occur without the need to add a carbon source, thereby enhancing the denitrification effect. In addition, pyrite can produce free iron ions, which can form iron phosphate precipitates with phosphates. Coupled with the adsorption and filtration effects of the lower zeolite layer 28, the removal effect of total phosphorus pollutants can be greatly improved, thereby achieving the purpose of efficient nitrogen and phosphorus removal from sewage.

[0042] Specifically, the denitrification ecological filter 14 is filled from top to bottom with a melon seed layer 26, a pyrite / pebble layer 27, a zeolite layer 28, and a pebble layer 29, with a filling ratio of 2:4:2:2, and the pyrite / pebble layer 27 has a pyrite and pebble mixing ratio of 1:2 to 1:3. The melon seed particle size is 5-20mm, the pyrite / pebble mixture and the zeolite particle size are 10-20mm, and the pebble particle size is 20-30mm. Canna and iris are planted above the denitrification ecological filter, and the planting ratio of canna and iris is 1:2 to 1:3.

[0043] Specifically, the sewage pump 6 divides the sewage in the regulating tank 1 into two parts, one part is pumped into the anaerobic reactor 9 through the sewage pump 6, and the other part is sent to the denitrification reactor 12 through the second sewage pump. Under the action of microorganisms on the biological filler in the anaerobic reactor 9, the difficult-to-degrade macromolecular pollutants are gradually decomposed into easily degradable small molecular pollutants, and at the same time, the phosphophilic bacteria are prompted to perform anaerobic phosphorus release. The sewage after the anaerobic reaction is sent to the first contact oxidation reactor 10 and the second contact oxidation reactor 11. Under the contact oxidation action of the above two levels of microorganisms, the COD in the sewage is fully degraded and the The ammonia nitrogen formed after the anaerobic reaction degrades the organic nitrogen is completely oxidized to form nitrate nitrogen. At the same time, phosphophilic bacteria also absorb phosphorus under aerobic conditions to remove phosphorus pollutants. The sewage then enters the denitrification reactor 12. Since the sewage in the direct denitrification reactor 12 contains a large amount of organic carbon source, it can fully undergo denitrification reaction, thereby removing a large amount of total nitrogen pollutants. The sewage after the denitrification reaction enters the third contact oxidation reactor 13, which can further remove residual ammonia nitrogen, COD and other pollutants. Finally, the effluent enters the denitrification ecological filter to further remove residual total nitrogen, total phosphorus and other pollutants, ensuring that the effluent meets the discharge standards.

[0044] A method for treating a rural domestic sewage denitrification and dephosphorization system comprises the following steps:

[0045] Step 1: Rural domestic sewage is pumped into the anaerobic reactor 9 by the sewage pump 6 after passing through the regulating tank 1. After the sewage undergoes anaerobic reaction for 2-6 hours, the anaerobic reactor 9 enters the first contact oxidation reactor 10 and the second contact oxidation reactor (11) in sequence through the liquid level difference. They stay for 4-8 hours for contact oxidation reaction respectively and then enter the denitrification reactor 12 through the liquid level difference.

[0046] Step 2: At the same time, the sewage pump 6 pumps the sewage entering the regulating tank 1 into the denitrification reactor 12 at a ratio of 10-30%. After the sewage undergoes denitrification reaction for 2-6 hours, it enters the third contact oxidation reactor 13 through the liquid level difference, stays in the third contact oxidation reactor 13 for 4-8 hours, and then enters the denitrification ecological filter (14). After 6-10 hours of reaction, the effluent meets the discharge standards.

[0047] In this implementation case, the operation effect of the above-mentioned nitrogen removal and phosphorus removal treatment system for rural domestic sewage was obtained through experiments, as shown in the following table:

[0048]

[0049] 1. When the water inlet volume is 800L / H, the COD of the inlet water is 240mg / L, the ammonia nitrogen content is 19.3mg / L, the total nitrogen content is 31.2mg / L, and the total phosphorus content is 3.3mg / L. After the denitrification and phosphorus removal treatment system, the COD of the effluent is 19mg / L, the ammonia nitrogen content is 0.04mg / L, the total nitrogen content is 5.23mg / L, and the total phosphorus content is 0.18mg / L, which meets the Level A standard of the National Pollutant Discharge Standard for Urban Wastewater Treatment Plants (GB18918-2002), that is, COD≤50mg / L, ammonia nitrogen≤5(8)mg / L, total nitrogen≤15mg / L, and total phosphorus≤0.5mg / L.

[0050] 2. When the inlet water volume is 1200L / H, the COD of the inlet water is 212 mg / L, the ammonia nitrogen content is 20.1 mg / L, the total nitrogen content is 34.4 mg / L, and the total phosphorus content is 3.6 mg / L. After the denitrification and phosphorus removal treatment system, the COD of the effluent is 23 mg / L, the ammonia nitrogen content is 0.68 mg / L, the total nitrogen content is 8.41 mg / L, and the total phosphorus content is 0.39 mg / L, which meets the Level A standard of the National Pollutant Discharge Standard for Urban Wastewater Treatment Plants (GB18918-2002), that is, COD ≤ 50 mg / L, ammonia nitrogen ≤ 5 (8) mg / L, total nitrogen ≤ 15 mg / L, and total phosphorus ≤ 0.5 mg / L.

[0051] 3. When the inlet water volume is 1600L / H, the COD of the inlet water is 332 mg / L, the ammonia nitrogen is 25.5 mg / L, the total nitrogen is 40.8 mg / L, and the total phosphorus is 5.4 mg / L. After the denitrification and phosphorus removal treatment system, the COD of the effluent is 36 mg / L, the ammonia nitrogen is 3.91 mg / L, the total nitrogen is 15.23 mg / L, and the total phosphorus is 0.61 mg / L, which meets the Level A standard of the Jiangsu Provincial Local Standard "Village Domestic Sewage Treatment Water Pollutant Discharge Standard (DB32 / T3462-2018)", that is, COD≤50 mg / L, ammonia nitrogen≤5(8) mg / L, total nitrogen≤20 mg / L, and total phosphorus≤1 mg / L.

[0052] The present invention relates to a denitrification and phosphorus removal system and treatment method for rural domestic sewage. Rural domestic sewage is treated by arranging a regulating tank 1, an anaerobic reactor 9, a first contact oxidation reactor 10, a second contact oxidation reactor 11, a denitrification reactor 12, a third contact oxidation reactor 13 and a denitrification ecological filter 14. When the sewage passes through the above-mentioned tank bodies, different microorganisms on the biological fillers can better remove pollutants such as COD, ammonia nitrogen, total phosphorus, total nitrogen and the like in the sewage, especially the treatment effect on total phosphorus and total nitrogen is better. Moreover, each tank body is independent of each other and can be combined or disassembled to adapt to different rural environments.

[0053] The second contact oxidation reactor 11 and the raw sewage are introduced into the denitrification reactor 12 together, so that the microorganisms use the organic matter in the raw sewage as a carbon source to carry out a denitrification reaction, remove nitrates in the sewage, and improve the denitrification and denitrification capacity of the traditional AAO system.

[0054] A solar photovoltaic power generation panel 2 is arranged, which is connected to an air pump 5 and a heater 3 in a regulating tank 1. On the one hand, the solar energy can be used to heat up the sewage to improve the ability of microorganisms to remove pollutants, especially in winter when the temperature is low, which can greatly improve the removal effect of pollutants; on the other hand, the solar energy can be converted into electrical energy to aerate the contact oxidation reactor through an air pump, thereby reducing the cost of sewage treatment.

[0055] The pyrite filler used in the denitrification ecological filter 14 can produce a large amount of sulfur elements and iron ions that can serve as electron donors. Autotrophic denitrification reaction can occur without the need to add a carbon source, thereby enhancing the denitrification effect. In addition, pyrite can produce free iron ions, which can form iron phosphate precipitates with phosphates. Coupled with the adsorption and filtration effects of the zeolite filler, the removal effect of total phosphorus pollutants can be greatly improved, thereby achieving the purpose of efficient denitrification and phosphorus removal of sewage.

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for removing nitrogen and phosphorus from rural domestic sewage, characterized in that: It comprises a regulating tank (1), a first treatment component, a second treatment component, an aeration component and a denitrification ecological filter (14); The regulating tank (1) is connected to the first treatment component and the second treatment component respectively, the first treatment component is connected to the second treatment component, and the second treatment component is connected to the denitrification ecological filter (14); the aeration component is connected to the first treatment component and the second treatment component respectively.

2. The denitrification and phosphorus removal system for rural domestic sewage according to claim 1, characterized in that: The first treatment component comprises an anaerobic reactor (9), a first contact oxidation reactor (10) and a second contact oxidation reactor (11); the inlet of the anaerobic reactor (9) is connected to the regulating tank (1) via a first pipeline (8), the outlet of the anaerobic reactor (9) is connected to the first contact oxidation reactor (10) via a third pipeline (31), the outlet of the first contact oxidation reactor (10) is connected to the inlet of the second contact oxidation reactor (11) via a fourth pipeline (32); the outlet of the second contact oxidation reactor (11) is connected to the second treatment component via a fifth pipeline (33); The first pipeline (8) is connected to a first sewage pump (6).

3. The denitrification and phosphorus removal system for rural domestic sewage according to claim 2, characterized in that: The second treatment component comprises a denitrification reactor (12) and a third contact oxidation reactor (13); the inlet of the denitrification reactor (12) is connected to a second pipeline (23), and the other end of the second pipeline (23) is connected to the regulating tank (1); the outlet of the denitrification reactor (12) is connected to the inlet of the third contact oxidation reactor (13) through a sixth pipeline (34), and the outlet of the third contact oxidation reactor (13) is connected to the denitrification ecological filter (14) through a seventh pipeline (35); The second pipeline (23) is connected to a second sewage pump.

4. The denitrification and phosphorus removal system for rural domestic sewage according to claim 3, characterized in that: The aeration assembly comprises an aeration main pipe (36), one end of which is connected to an air pump (5); the first contact oxidation reactor (10) and the second contact oxidation reactor (11) are each connected to the aeration main pipe (36) via a first aeration pipe (37); and the third contact oxidation reactor (13) is connected to the aeration main pipe (36) via a second aeration pipe (38).

5. The rural domestic sewage denitrification and phosphorus removal system according to claim 4, characterized in that: A solar photovoltaic panel (2) is arranged on the regulating pool (1); the solar photovoltaic panel (2) is respectively connected to a heating switch (4) and an air pump switch (7) through a solar controller; the other end of the heating switch (4) is connected to a heater (3); the other end of the air pump switch (7) is connected to the air pump (5); the heater (3) is located in the regulating pool (1).

6. The rural domestic sewage denitrification and phosphorus removal system according to claim 3, characterized in that: The anaerobic reactor (9), the first contact oxidation reactor (10), the second contact oxidation reactor (11), the denitrification reactor (12) and the third contact oxidation reactor (13) are all provided with an upper cover plate (16) at the upper end and a circular arc bottom (20) at the lower end; a filler (17) is provided inside, and a water-permeable plate (18) is provided inside, and a plurality of water-permeable holes (22) are provided on the water-permeable plate (18).

7. The rural domestic sewage denitrification and phosphorus removal system according to claim 3, characterized in that: The denitrification ecological filter (14) is connected to the seventh pipeline (35) through the filter inlet pipe (24) and discharged through the filter outlet pipe (30); a pebble layer (29) is arranged on the bottom surface of the filter inlet pipe (24), a zeolite layer (28) is arranged above the pebble layer (29), a pyrite / pebble layer (27) is arranged above the zeolite layer (28), a melon seed layer (26) is arranged above the pyrite / pebble layer (27), and canna and iris (25) are arranged above the melon seed layer (26).

8. A method for treating a rural domestic sewage denitrification and dephosphorization system, characterized in that: The following steps are involved: Step 1: Rural domestic sewage is pumped into an anaerobic reactor (9) by a sewage pump (6) after passing through a regulating tank (1). After the sewage undergoes anaerobic reaction for 2-6 hours, the anaerobic reactor (9) sequentially enters a first contact oxidation reactor (10) and a second contact oxidation reactor (11) through a liquid level difference, and stays for 4-8 hours for contact oxidation reaction respectively before entering a denitrification reactor (12) through a liquid level difference. Step 2: At the same time, the sewage pump (6) pumps the sewage entering the regulating tank (1) into the denitrification reactor (12) at a ratio of 10-30%. After the sewage undergoes denitrification reaction for 2-6 hours, it enters the third contact oxidation reactor (13) through the liquid level difference, stays in the third contact oxidation reactor (13) for 4-8 hours, and then enters the denitrification ecological filter (14). After 6-10 hours of reaction, the effluent meets the discharge standards.

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