Micro-aeration baffling constructed wetland biological treatment system and treatment method thereof

Abstract

The application provides a micro-aeration baffling constructed wetland biological treatment system and a treatment method thereof. The system comprises a water storage pool for storing sewage to be treated; a baffling constructed wetland main body, which is divided into multiple compartments by vertical partitions, so that the sewage forms an up-and-down baffling path; the baffling constructed wetland main body comprises a water inlet area, an aeration wetland area, a sedimentation buffer area and a water outlet area which are sequentially connected; the water inlet area is communicated with a water outlet of the water storage pool; a microporous aeration device is arranged at the bottom of the aeration wetland area and is used for providing oxygen to maintain an aerobic environment; a denitrification tank is arranged downstream of the baffling constructed wetland main body, a water inlet of the denitrification tank is communicated with the water outlet area, and the denitrification tank is filled with pyrite particle fillers in the inside and is used for autotrophic denitrification and simultaneous phosphorus removal of the wetland effluent.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a micro-aeration baffled constructed wetland biological treatment system and its treatment method. Background Technology

[0002] In existing rural domestic sewage treatment, constructed wetland technology is widely used due to its simple structure, stable operation, and ability to be miniaturized and dispersed. Its denitrification mainly relies on the nitrification-denitrification of microorganisms on the surface of the packing material, while phosphorus removal relies on adsorption by the packing material, absorption by plants, and assimilation by microorganisms.

[0003] However, in practical applications, problems such as limited nitrogen removal efficiency and insufficient carbon sources still exist. Rural domestic sewage generally has low carbon and nitrogen content, resulting in a severe lack of carbon sources during the denitrification stage, making it difficult to meet the total nitrogen removal rate target. Furthermore, existing constructed wetlands often place nitrification and denitrification functions within the same unit. Dissolved oxygen generated by aeration in the aerobic zone can flow into the anoxic zone with the water flow, disrupting the anoxic environment required for denitrification and inhibiting the activity of denitrifying bacteria. This leads to mutual constraints between nitrification and denitrification functions, making it difficult to control their respective operating parameters. In addition, traditional constructed wetlands rely mainly on adsorption by packing materials for phosphorus removal, which has a limited adsorption capacity and is easily saturated. Plant absorption and microbial assimilation result in low phosphorus removal, making it difficult to handle mixed rural sewage with high total phosphorus concentrations, such as aquaculture wastewater. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a micro-aeration baffled constructed wetland biological treatment system and treatment method thereof.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, a micro-aeration baffled constructed wetland biological treatment system is characterized by comprising: a water storage tank for storing wastewater to be treated; The main body of the deflector constructed wetland is divided into multiple compartments by vertical partitions, which creates a deflector flow path for wastewater. The main body of the deflector constructed wetland includes an inlet area, an aeration wetland area, a sedimentation buffer zone, and an outlet area that are connected in sequence. The inlet area is connected to the outlet of the water storage tank. A microporous aeration device is located at the bottom of the aerated wet area to provide oxygen to maintain an aerobic environment; The denitrification tank is located downstream of the main body of the deflector constructed wetland. Its inlet is connected to the effluent area. The tank is filled with pyrite granular filler and is used to perform autotrophic denitrification and nitrogen removal and simultaneous phosphorus removal on the wetland effluent.

[0006] Optionally, the water storage tank is equipped with a stirring paddle to agitate the wastewater and prevent pollutants from settling.

[0007] Optionally, the aerated wet zone is filled with a composite filler composed of zeolite, volcanic rock, and activated carbon.

[0008] Optionally, the main body of the deflector constructed wetland consists of four compartments along the water flow direction: the first compartment is a downflow inlet area, and the bottom of the first compartment has a channel communicating with the second compartment; the second compartment is an upflow aeration wetland area, and the upper part of the side wall of the second compartment near the third compartment has multiple flow holes; the third compartment is a downflow sedimentation buffer zone, and the bottom of the third compartment has a channel communicating with the fourth compartment; the fourth compartment is an upflow outlet area.

[0009] Optionally, the denitrification tank is an upflow anoxic reaction tank, inoculated with autotrophic denitrifying activated sludge, and uses pyrite particles as electron donors for autotrophic denitrifying bacteria.

[0010] Secondly, a method for simultaneous nitrogen and phosphorus removal treatment of rural domestic sewage using the above-mentioned system includes the following steps: Rural domestic sewage to be treated is fed into the storage tank and stirred evenly by a stirring paddle before being pumped into the inlet area of ​​the main body of the baffled constructed wetland. Within the main body of the baffled constructed wetland, the sewage flows sequentially through the inlet area, the aerated wetland area, and the effluent area along an upper and lower baffle path. In the aerated wetland area, a microporous aeration device is activated to maintain aerobic conditions. Ammonia nitrogen in the sewage undergoes nitrification under the action of nitrifying bacteria attached to the composite packing material, converting it into nitrate nitrogen. Simultaneously, some organic matter is degraded by aerobic microorganisms, and some phosphorus is removed by adsorption through the packing material. The sewage then enters a sedimentation buffer zone for mud-water separation, and the supernatant flows into the effluent area. The supernatant from the effluent area is introduced into a denitrification tank filled with pyrite particles. Under anoxic conditions, using pyrite as an electron donor, autotrophic denitrifying microorganisms reduce nitrate nitrogen to nitrogen gas, achieving deep denitrification. Simultaneously, the adsorption and sedimentation effects of pyrite are used to remove phosphorus from the sewage, which is then discharged as effluent.

[0011] Optionally, the dissolved oxygen concentration in the aerated wet zone is maintained at 2–4 mg / L through microporous aeration; the total hydraulic retention time is 12–18 hours.

[0012] Optionally, the particle size of the pyrite particles is 2 to 4 mm.

[0013] Optionally, the influent water quality of the rural domestic sewage is: COD 300-400 mg / L, NH4+ + -N 100~130mg / L, TN 160~200 mg / L, TP 8~12 mg / L.

[0014] Optionally, the sedimentation buffer zone is provided with a device for enhancing mud-water separation, which is an inclined tube sedimentation device, an inclined plate sedimentation device, or a baffle.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention spatially separates the main body of the baffled constructed wetland from the denitrification tank, achieving functional zoning and independent control of nitrification and denitrification. The front-end baffled wetland uses microporous aeration to maintain an aerobic environment and utilizes a composite packing material of zeolite, volcanic rock, and activated carbon to enhance ammonia nitrification, avoiding the problem of mutual interference between aerobic and anoxic zones in traditional constructed wetlands. The rear-end denitrification tank uses pyrite as an electron donor for autotrophic denitrification, requiring no external organic carbon source, making it suitable for rural domestic wastewater with low C / N ratios. Simultaneously, the adsorption and sedimentation effects of pyrite remove phosphorus, overcoming the limited phosphorus removal capacity of current constructed wetlands. The sedimentation buffer zone of the baffled wetland enables mud-water separation, reducing the concentration of suspended solids in the effluent and minimizing the risk of blockage in the rear-end denitrification tank. The spatial separation of the two units allows for natural attenuation of dissolved oxygen in the front-end effluent, reducing the consumption of pyrite electron donors and the inhibition of autotrophic denitrifying bacteria, thus improving the system's synergy and stability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Legend: Figure 1 This is a system model diagram of the present invention; Figure 2 The diagram shows the COD changes under different operating conditions of the constructed wetland system reactor; (a) a detailed diagram of COD changes during long-term operation; (b) COD changes during the aerobic nitrification stage of the constructed wetland. Figure 3 TN and NH4 under different operating conditions of constructed wetland system reactors + -N variation graph; (a) Detailed results of TN changes during long-term operation; (b) NH4+ during the aerobic nitrification stage of the constructed wetland. + -N change; Figure 4 The diagram shows the changes in total phosphorus (TP) under different operating conditions of the integrated constructed wetland system reactor; (a) a detailed diagram of TP changes during long-term operation; (b) TP changes during the aerobic nitrification stage of the constructed wetland. Figure 5 The change in SS concentration in the constructed wetland system; Figure 6 NO3 for the autotrophic denitrification stage - -N influent and effluent concentration changes and removal rate.

[0018] In the diagram: 1. Water storage tank; 2. Supplemental lighting; 3. Peristaltic pump; 4. Aeration pump; 5. First compartment; 6. Second compartment; 7. Main body of constructed wetland; 8. First sampling port; 9. Second sampling port; 10. Third sampling port; 11. Fourth sampling port; 12. Wastewater return sampling port; 13. Sedimentation buffer zone; 14. Effluent zone; 15. Effluent outlet; 16. Denitrification tank. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It will be understood that although the terms “first,” “second,” “third,” “fourth,” etc., may be used here to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0021] Combination Figure 1-6 As shown, the present invention provides a micro-aeration baffled constructed wetland biological treatment system, comprising, from left to right, a water storage tank 1, a supplemental lighting lamp 2, a peristaltic pump 3, a baffled constructed wetland body 7, a denitrification tank 16, and an aeration pump 4 for aeration. Wastewater enters the baffled constructed wetland body 7 from the water storage tank 1 under the action of the peristaltic pump 3, flows sequentially through each functional area of ​​the baffled constructed wetland body 7 along the baffle path, and is finally discharged from the denitrification tank 16.

[0022] The storage tank 1 is used to store rural domestic sewage awaiting treatment. The storage tank 1 is equipped with a stirring paddle, driven by a small motor to rotate continuously at low speed, preventing the sedimentation of suspended solids and insoluble particles in the sewage and ensuring uniform influent water quality. The outlet of the storage tank 1 is connected to the inlet of the peristaltic pump 3 via a silicone hose. The peristaltic pump 3 is an adjustable-speed pump that pumps the sewage into the main body 7 of the deflector-type constructed wetland at a set flow rate. Supplemental lighting 2 is installed above the storage tank 1 and the main wetland body to provide supplemental light for plant growth, especially on cloudy or rainy days or when used indoors, to maintain the photosynthesis of aquatic plants.

[0023] The main body 7 of the deflected constructed wetland is made of glass. Its interior is divided into four compartments from left to right by three vertical partitions along the water flow direction, namely the first compartment 5, the second compartment 6, the third compartment, and the fourth compartment. The sewage flow direction is a deflected flow path of downflow-upflow-downflow-upflow.

[0024] The first compartment 5 is the water inlet area, with downward flow. It has an inlet at the top, which is connected to the peristaltic pump 3 via an inlet pipe. The bottom of the first compartment 5 has a channel that connects to the second compartment 6, through which sewage enters the second compartment 6.

[0025] The second compartment 6 is the aerated wet zone, with upward flow. The interior of the second compartment 6 is filled with composite packing material, the packing layer having a certain height. The composite packing material is a mixture of zeolite, volcanic rock, and activated carbon in a volume ratio of 3:5:2. The zeolite particles have a diameter of 2–4 mm, the volcanic rock particles 4–8 mm, and the activated carbon particles 1–3 mm. The three types of packing material are layered, with a bottom layer of volcanic rock as a support layer, a middle layer of the zeolite and activated carbon mixture, and a top layer of volcanic rock to prevent excessive compaction by plant roots. Aquatic emergent plants (such as yellow iris) are planted on the surface of the packing layer. Microporous aeration pipes are laid at the bottom of the second compartment 6, connected to the aeration pump 4. The aeration pipes have evenly distributed micropores to generate microbubbles, improving oxygen mass transfer efficiency. The aeration rate is adjusted by a valve on the aeration pump 4 to maintain a dissolved oxygen concentration of 2–4 mg / L in the water. In the second compartment 6, in addition to aerobic nitrification, due to the potential presence of a localized anoxic microenvironment within the packing layer, heterotrophic denitrifying bacteria attached to the packing surface can utilize organic carbon sources in the wastewater to reduce some of the nitrate nitrogen produced by nitrification into nitrogen gas. This achieves front-end heterotrophic denitrification, forming a synergistic denitrification process with the back-end autotrophic denitrification of pyrite. Multiple flow holes are provided on the upper side wall of the second compartment 6 near the third compartment to facilitate the upward flow of wastewater into the third compartment.

[0026] The third compartment is a sedimentation buffer zone 13, with downward flow. An inclined tube sedimentation device is installed at its lower part for sludge-water separation. Above the inclined tube device is the clear water zone, and below is the sludge hopper. The bottom of the sludge hopper has a sludge discharge pipe and a sludge return pipe. Wastewater enters the third compartment from the second compartment 6 through the upper flow hole and flows downwards. Suspended solids settle on the surface of the inclined tubes and slide down into the sludge hopper. Clarified wastewater enters the fourth compartment through a channel at the bottom of the third compartment. The side wall of the third compartment has a first sampling port 8, a second sampling port 9, and a third sampling port 10 along its height, corresponding to the upper, middle, and lower positions of the sedimentation buffer zone 13, respectively, for detecting water quality and sludge concentration at different depths. The lowest sampling port 11 is located in the sludge hopper and is used to monitor sludge accumulation and sludge return concentration. The wastewater return sampling port 12 is located at the lowest point of the sludge hopper and is connected to a sludge return pump via a hose to return some of the settled sludge to the first compartment 5, thereby improving the microbial concentration and treatment efficiency within the system.

[0027] The fourth compartment is the effluent zone 14, which is an upward flow zone. Its bottom is connected to the third compartment, and its top has an outlet. Wastewater enters from the bottom and flows upward, where residual suspended solids settle naturally before finally flowing out from the top outlet.

[0028] Denitrification tank 16 is a cylindrical glass reactor with an upflow structure. It has an inlet at the bottom, connected to the outlet of the fourth compartment via a silicone tube; and an outlet at the top. The interior of denitrification tank 16 is filled with pyrite particles, 2–4 mm in diameter, at a moderate height to maintain appropriate porosity. The pyrite particles undergo acid washing and water washing pretreatment before use to remove surface impurities. Denitrification tank 16 is inoculated with autotrophic denitrifying activated sludge. During operation, wastewater enters from the bottom and flows upward through the pyrite packing layer. Under anoxic conditions, autotrophic denitrifying bacteria use pyrite as an electron donor to reduce nitrate nitrogen in the wastewater to nitrogen gas. Simultaneously, iron ions on the surface of the pyrite combine with phosphate ions to form precipitates, achieving simultaneous phosphorus removal. Denitrification tank 16 has an overflow weir and an effluent tank at the top, with the final effluent discharged through a pipeline. To maintain the anoxic environment, denitrification tank 16 is completely sealed, with only an exhaust vent for discharging the generated nitrogen gas.

[0029] To facilitate the monitoring of pollutant removal efficiency in each treatment unit, the system is equipped with multiple sampling ports: the first sampling port 8 is located above the inclined tube sedimentation zone in the third compartment and is used to monitor water quality before sedimentation; the second sampling port 9 is located in the middle of the third compartment and is used to monitor water quality changes during sedimentation; the third sampling port 10 is located in the clear water zone at the bottom of the third compartment and is used to monitor water quality entering the fourth compartment after sedimentation; the fourth sampling port 11 is located inside the sludge hopper in the third compartment and is used to take sludge samples for analysis of sludge concentration and activity; the wastewater return sampling port 12 is located at the lowest point of the sludge hopper and can be used as both a sludge return outlet and a sludge discharge outlet; sampling interfaces are also reserved at the inlet and outlet of the denitrification tank 16 for water quality analysis.

[0030] The specific method for treating rural domestic sewage using the above system is as follows: Collected rural domestic sewage is poured into storage tank 1, the agitator is turned on, and supplemental lighting 2 is simultaneously turned on to maintain plant illumination. Peristaltic pump 3 is started, pumping the sewage into the first compartment 5 of the main body 7 of the deflector-type constructed wetland at a set flow rate. The speed of peristaltic pump 3 is adjusted to control the total hydraulic retention time at 12–18 hours. After entering the first compartment 5, the sewage flows downwards and enters the second compartment 6 through the bottom channel. Simultaneously, aeration pump 4 is turned on, supplying air to the second compartment 6 through microporous aeration pipes, adjusting the aeration rate to maintain the dissolved oxygen concentration at 2–4 mg / L. In the second compartment 6, the sewage flows upwards, and aerobic microorganisms on the surface of the composite packing material degrade organic matter and oxidize ammonia nitrogen to nitrate nitrogen. Simultaneously, the localized anoxic microenvironment inside the packing layer promotes heterotrophic denitrifying bacteria to utilize the organic carbon source in the influent to reduce some nitrate nitrogen to nitrogen gas, achieving denitrification. Some phosphorus is removed through adsorption by the packing material and absorption by the plants. Wastewater enters the third compartment through the upper flow hole of the second compartment 6, flowing downwards through the inclined tube sedimentation zone. Sludge settles on the inclined tubes and slides down into the sludge hopper, while clarified wastewater enters the fourth compartment through the bottom channel. The sludge return pump is periodically activated to transport a portion of the sludge in the sludge hopper (sludge return ratio 20%–30%) to the first compartment 5 via the wastewater return sampling port 12 to replenish the upstream microbial biomass; the remaining sludge is periodically discharged through the sludge discharge pipe. Wastewater flows upwards in the fourth compartment, further clarified, and then enters the denitrification tank 16 through the top outlet. The denitrification tank 16 is an upflow anoxic reactor; wastewater enters from the bottom and flows upwards through the pyrite packing layer. In anoxic conditions, pyrite acts as an electron donor, and autotrophic denitrifying bacteria reduce nitrate nitrogen to nitrogen gas. Simultaneously, adsorption and precipitation on the pyrite surface remove phosphorus. Finally, the effluent overflows from the top.

[0031] Using the above system and methods, a continuous operation test of over 200 days was conducted on actual rural domestic sewage. First, aerobic activated sludge was acclimated under mesophilic conditions for 30 days to cultivate sludge capable of treating domestic sewage under aerobic conditions. The influent organic load was controlled by adjusting the hydraulic retention time. Experiments showed that when the hydraulic retention time was 12 hours, COD and NH4+ levels were significantly reduced. + The average removal rates of -N and TP were 86.34±1.14%, 91.72±0.87%, and 36.65±1.36%, respectively; when the hydraulic retention time was reduced to 8 hours, the removal rates of COD and NH4+ were significantly reduced. + The average removal rates of -N and TP decreased to 78.14±1.21%, 85.28±1.89%, and 31.81±6.97%, respectively. Therefore, a hydraulic retention time of 12 hours is the critical point for this constructed wetland, and also the minimum hydraulic retention time it can withstand. After replanting the cultivated calamus with a hydraulic retention time of 8 hours, COD and NH4+ levels decreased. +The average removal rates of nitrogen and phosphorus were slightly increased, indicating that plants in wetlands absorbed some organic matter and nitrogen and phosphorus through their own growth, thus playing a role in pollutant removal.

[0032] The constructed wetland operated stably during the aerobic nitrification stage. The influent COD concentration was 300–400 mg / L, and NH4+ concentration was [missing information]. + When the -N concentration is 100–130 mg / L, the NO3 in the effluent during the aerobic stage is... - The -N concentration was 60–70 mg / L, indicating that the nitrification reaction proceeded steadily. The influent TP concentration was 10±2 mg / L. During the aerobic stage, phosphorus removal mainly relied on adsorption by the packing material. Plant and microbial growth only removed a small portion of the TP. The TP removal rate during the aerobic stage was basically maintained at 36.65±1.36%, and the average effluent concentration was 5–7 mg / L.

[0033] Upflow denitrification tank 16 was used for pyrite autotrophic denitrification. With the influent nitrate nitrogen concentration maintained at 60–70 mg / L, the nitrate nitrogen concentration in the denitrification effluent remained consistently low, below 5 mg / L for most of the time points, and below 2 mg / L in most cases. The nitrate nitrogen removal rate remained stable above 90% during this stage, approaching or reaching 95%–100% for most of the time points. The TP concentration in the constructed wetland effluent remained around 5 mg / L, while the final TP concentration in the denitrification tank 16 was consistently below 1 mg / L, below 0.5 mg / L for most of the time points, and the TP removal rate remained consistently stable at 80%–90%.

[0034] Through the above structure and operation mode, the wastewater undergoes organic oxidation, nitrification, and autotrophic denitrification for nitrogen and phosphorus removal in sequence. The treatment process is completed without the need for additional complex equipment and external carbon sources, which reduces the system's energy consumption cost and carbon emissions. It is suitable for in-situ, low-carbon treatment of decentralized rural wastewater.

[0035] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A micro-aeration baffled constructed wetland biological treatment system, characterized in that, include: Water storage tank (1) for storing wastewater to be treated; The main body of the deflecting constructed wetland (7) is divided into multiple areas, including an inlet area, an aeration wetland area, a sedimentation buffer zone (13) and an outlet area (14) connected in sequence, so that the sewage forms an up-and-down deflecting path; the inlet area is connected to the outlet of the water storage tank (1); A microporous aeration device is located at the bottom of the aerated wet area; The denitrification tank (16) is located downstream of the main body (7) of the deflector constructed wetland. Its inlet is connected to the outlet area (14). It is filled with pyrite particle packing material to perform autotrophic denitrification and phosphorus removal on the wetland effluent.

2. The micro-aeration baffled constructed wetland biological treatment system according to claim 1, characterized in that, The water storage tank (1) is equipped with a stirring paddle for stirring the sewage to prevent pollutants from settling.

3. The micro-aeration baffled constructed wetland biological treatment system according to claim 1, characterized in that, The aerated wet zone is filled with composite filler, which consists of zeolite, volcanic rock and activated carbon.

4. The micro-aeration baffled constructed wetland biological treatment system according to claim 1, characterized in that, The main body (7) of the deflector constructed wetland consists of four compartments along the water flow direction. The first compartment (5) is the inlet area for downward flow, and the bottom of the first compartment (5) has a channel communicating with the second compartment (6). The second compartment (6) is the aeration wet area for upward flow, and the upper part of the side wall of the second compartment (6) near the third compartment has multiple flow holes. The third compartment is the sedimentation buffer zone (13) for downward flow, and the bottom of the third compartment has a channel communicating with the fourth compartment. The fourth compartment is the outlet area (14) for upward flow.

5. The micro-aeration baffled constructed wetland biological treatment system according to claim 1, characterized in that, The denitrification tank (16) is an upflow anoxic reaction tank, inoculated with autotrophic denitrifying activated sludge, and uses pyrite particles as electron donors for autotrophic denitrifying bacteria.

6. A method for simultaneous nitrogen and phosphorus removal treatment of rural domestic sewage using the system described in any one of claims 1 to 5, characterized in that, Includes the following steps: Wastewater flows sequentially through the inlet zone, aeration wetland zone, sedimentation buffer zone (13) and outlet zone (14) within the main body (7) of the deflection constructed wetland. The aeration wetland zone is filled with composite filler, and the bottom is maintained with aerobic conditions by a microporous aeration device, so that the ammonia nitrogen in the wastewater undergoes nitrification. The wetland effluent enters a denitrification tank (16) filled with pyrite particles. Under anoxic conditions, the pyrite serves as an electron donor, and autotrophic denitrifying microorganisms reduce nitrate nitrogen to nitrogen gas. Simultaneously, the adsorption and precipitation effects of the pyrite are utilized to remove phosphorus.

7. The method for simultaneous nitrogen and phosphorus removal treatment of rural domestic sewage according to claim 6, characterized in that, The aerated wet zone maintains a dissolved oxygen concentration of 2–4 mg / L through microporous aeration; the total hydraulic retention time is 12–18 hours.

8. The method for simultaneous nitrogen and phosphorus removal treatment of rural domestic sewage according to claim 6, characterized in that, The particle size of the pyrite particles is 2 to 4 mm.

9. The method for simultaneous nitrogen and phosphorus removal treatment of rural domestic sewage according to claim 6, characterized in that, The influent water quality of the rural domestic sewage is as follows: COD 300-400 mg / L, NH4+ + -N 100~130 mg / L, TN 160~200 mg / L, TP 8~12 mg / L.

10. The method for simultaneous nitrogen and phosphorus removal treatment of rural domestic sewage according to claim 6, characterized in that, The sedimentation buffer zone (13) is equipped with a device for mud-water separation, which is an inclined tube sedimentation device, an inclined plate sedimentation device, or a baffle.

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