Zero-carbon source zero-concentrate liquid aged landfill leachate treatment method and system

Abstract

The application discloses a zero-carbon-source zero-concentrated-liquid aged landfill leachate treatment method and system, wherein the leachate is first sent into a sulfur autotrophic denitrification tank for short-range denitrification and denitrogenation, the effluent is subjected to a nitrosation reaction to realize the conversion of part of ammonia nitrogen into nitrite, the main denitrogenation is completed through an anaerobic ammonia oxidation tank, the anaerobic ammonia oxidation effluent is partially backflowed to the front-end sulfur autotrophic denitrification tank to complete the conversion of nitrate, the remaining effluent is subjected to a nitrification-sulfur autotrophic denitrification deep denitrogenation and deep treatment system to remove refractory pollutants, and finally, the effluent is treated through a sulfur autotrophic denitrification filter tank to reach the discharge standard. The application utilizes the reduced sulfur compounds generated by landfill site desulfurization of marsh gas as a sulfur source, does not need to add a carbon source, has no secondary pollution of concentrated liquid, greatly reduces the treatment energy consumption and operation cost, simultaneously realizes the resource utilization of solid waste, the effluent can stably reach the standard, and is suitable for the treatment and disposal of aged landfill leachate.

Description

Technical Field

[0001] This invention relates to the field of landfill leachate treatment technology, specifically to a method and system for treating leachate from aged landfills with zero carbon source and zero concentrate. Background Technology

[0002] Currently, most cities have landfills, generating large amounts of leachate. With the gradual commissioning of waste incineration plants, landfill volumes are decreasing, and some landfills are even entering their closure period, resulting in large quantities of leachate from older landfills. This older leachate presents challenges such as high ammonia nitrogen, low C / N ratio, high salinity, and high sulfides. Conventional treatment processes involve adding carbon sources and using heterotrophic denitrification to remove ammonia nitrogen and total nitrogen. This results in high carbon source and electricity consumption, high operating costs, and difficulties in achieving treatment standards.

[0003] However, most landfills operate under DTRO emergency treatment conditions, resulting in landfill gas containing large amounts of hydrogen sulfide (200-600 mg / m³) generated under anaerobic conditions from accumulated leachate. During the desulfurization process of biogas power generation, significant amounts of elemental sulfur or ferrous sulfide are produced, and these reduced sulfides are mostly treated as solid waste. Meanwhile, heterotrophic denitrification of leachate often relies on external carbon sources. Utilizing the reduced sulfides generated on-site as a sulfur source for autotrophic denitrification would significantly reduce the amount of purchased carbon sources, sludge volume, and energy consumption. Based on this, and considering the high ammonia nitrogen and low C / N ratio characteristics of leachate from aged landfills, an anaerobic ammonia oxidation process is employed to remove most ammonia nitrogen and total nitrogen. Then, the reduced sulfides in the influent leachate and the sulfides generated during biogas desulfurization are used for autotrophic denitrification to remove residual nitrate nitrogen and total nitrogen, resulting in extremely high economic and environmental benefits. Summary of the Invention

[0004] To address the problems of insufficient carbon source, high energy consumption, high operating costs, and easy secondary pollution from concentrate in the treatment of leachate from aged landfills in existing technologies, this invention provides a method and system for treating leachate from aged landfills with zero carbon source and zero concentrate.

[0005] The first objective of this invention is to provide a method for treating leachate from aged landfills with zero carbon source and zero concentrate, comprising: Step 1: After being lifted and filtered by the equalization tank lift pump, the leachate from the old waste enters the sulfur autotrophic denitrification tank for short-cut denitrification and denitrification treatment. The hydrogen sulfide contained in the influent leachate and the reducing sulfur particles produced by the biogas desulfurization in the site are used to reduce the nitrate nitrogen in the anaerobic ammonia oxidation water to nitrogen gas and nitrite. Step 2: The effluent from the sulfur autotrophic denitrification tank enters the nitrite reaction tank, where some of the ammonia nitrogen in the leachate is converted into nitrite. Step 3: The effluent from the nitrification reaction tank enters the first sedimentation tank for mud-water separation. The supernatant after separation enters the anaerobic ammonia oxidation tank, where anaerobic ammonia oxidizing bacteria convert ammonia nitrogen and nitrite in the influent into nitrogen gas. Step 4: The effluent from the anaerobic ammonia oxidation tank enters the second sedimentation tank for mud-water separation. The separated effluent enters the intermediate tank for temporary storage. Part of the effluent from the intermediate tank is returned to the sulfur autotrophic denitrification tank described in Step 1 for denitrification and nitrogen removal reaction. Step 5: The remaining effluent from the intermediate tank enters the nitrification filter, and the effluent from the nitrification filter enters the first-stage sulfur autotrophic denitrification filter. Through sulfur autotrophic denitrification and nitrification, the remaining recalcitrant COD, ammonia nitrogen and total nitrogen pollutants are removed, so that the ammonia nitrogen, nitrate nitrogen and nitrite nitrogen in the produced water meet the discharge standards. Step 6: The effluent from the first-stage sulfur autotrophic denitrification filter enters the advanced treatment system, which uses advanced catalytic oxidation or single-stage or multi-stage membrane systems to remove organic matter and organic nitrogen that are difficult to remove by biological means, so that the effluent COD, SS, color and other indicators meet the discharge standards. Step 7: The effluent from the deep treatment system enters the second-stage sulfur autotrophic denitrification filter to remove nitrate nitrogen and nitrite nitrogen, so that the effluent can stably meet the standards and be discharged after treatment. Step 8: The sludge generated by the sulfur autotrophic denitrification tank, nitrification reaction tank, anaerobic ammonia oxidation tank, nitrification filter, sulfur autotrophic denitrification filters at all levels, and deep treatment system is discharged into the sludge dewatering system and transported off-site for disposal after dewatering.

[0006] Furthermore, the sulfur autotrophic denitrification filter material used in the sulfur autotrophic denitrification tank, the first-stage sulfur autotrophic denitrification filter tank, and the second-stage sulfur autotrophic denitrification filter tank is ferrous sulfide particles generated by dry desulfurization of biogas inside the landfill or other sulfur sources that can be used as denitrification denitrification substrates.

[0007] Furthermore, in step 2, the nitrification reactor is an aerobic reactor. By controlling the dissolved oxygen at 0.3-0.8 mg / L and the sludge age, stable nitrification is achieved, converting some of the influent ammonia nitrogen into nitrite nitrogen, which, together with the nitrite produced in the sulfur autotrophic denitrification tank, serves as the reaction substrate for anaerobic ammonia oxidation.

[0008] Furthermore, in step 3, the anaerobic ammonia oxidation tank adopts a biofilm anaerobic ammonia oxidation process with added packing material. The packing material is covered with anaerobic ammonia oxidation granular sludge, and the packing material filling degree is 30%-60%. The operating control conditions are pH value 7.2-8.3, temperature 28-37℃, and dissolved oxygen 0.2-0.8mg / L, achieving ammonia nitrogen removal of more than 90% and total nitrogen removal of more than 80%.

[0009] Furthermore, in step 4, the recirculation ratio of the intermediate tank effluent to the sulfur autotrophic denitrification tank is 100%-400%, that is, 50%-80% of the intermediate tank effluent is recirculated to the sulfur autotrophic denitrification tank for sulfur autotrophic denitrification, converting the small amount of nitrate nitrogen produced by the anaerobic ammonia oxidation system into nitrogen gas and nitrite.

[0010] Furthermore, in step 5, the treatment order of the nitrification filter and the first-stage autotrophic denitrification filter can be reversed according to the project situation, with the autotrophic denitrification filter first and the nitrification filter second, and denitrification circulation is achieved by pump recirculation to improve the pollutant removal rate; the effluent from the first-stage autotrophic denitrification filter can be partially recirculated to the nitrification filter for treatment.

[0011] Furthermore, in step 6, the deep treatment system is used to remove pollutants such as recalcitrant organic matter, organic nitrogen, and total phosphorus that are difficult to treat biochemically. It can employ one or more advanced catalytic oxidation systems, including advanced catalytic oxidation technologies such as Fenton catalytic oxidation, ultraviolet photocatalytic oxidation, and ozone catalytic oxidation, which aim to degrade recalcitrant COD, organic nitrogen, and other pollutants. Alternatively, it can employ a membrane system based on special material separation membranes, including single-stage or multi-stage material membranes with a molecular weight cutoff of approximately 200-10000 Da. The concentrated liquid from the material membrane is discharged into the remaining sludge for dewatering and disposal or refilling into a landfill.

[0012] Furthermore, in step 7, the effluent from the deep treatment system, after being treated by the second-stage sulfur autotrophic denitrification filter, can stably meet the standards in Table 2 of the "Pollution Control Standard for Municipal Solid Waste Landfills" (GB16889-2024); the effluent from the deep treatment system can be directly discharged through bypass pipelines.

[0013] Furthermore, in steps 3 and 4, the first sedimentation tank and the second sedimentation tank can be radial flow sedimentation tanks, vertical flow sedimentation tanks, or inclined plate sedimentation tanks, with inclined plate sedimentation tanks being preferred, and a hydraulic load of 1~4 m / h.

[0014] The second objective of this invention is to provide a zero-carbon-source, zero-concentrate leachate treatment system for aged landfills, used to implement the above-mentioned treatment method. The system comprises, in sequence along the water flow direction, a sulfur autotrophic denitrification tank, a nitrification reaction tank, a first sedimentation tank, an anaerobic ammonia oxidation tank, a second sedimentation tank, an intermediate tank, a nitrification filter, a first-stage sulfur autotrophic denitrification filter, a deep treatment system, and a second-stage sulfur autotrophic denitrification filter. The intermediate tank is equipped with a return pipeline, the outlet of which is connected to the inlet of the sulfur autotrophic denitrification tank. The system also includes a sludge dewatering system. The sludge discharge outlets of the first sedimentation tank, the second sedimentation tank, the nitrification filter, the first-stage autotrophic denitrification filter, the advanced treatment system, and the second-stage autotrophic denitrification filter are all connected to the sludge dewatering system. The sludge generated from the autotrophic denitrification tank, the nitrite reaction tank, the anaerobic ammonia oxidation tank, the nitrification filter, the denitrification filter, the advanced treatment system, and the autotrophic denitrification filter is sent to the sludge dewatering system for dewatering and disposal.

[0015] Furthermore, the system also includes a blower connected to the nitrification reaction tank and the nitrification filter tank to provide dissolved oxygen required for the aerobic reaction; the system also includes a nutrient dosing system to add nutrients required for microbial growth into the reaction system.

[0016] Furthermore, the intermediate pool is equipped with a reflux pump or air-lift reflux device and a reflux ratio adjustment unit on the reflux pipeline, with the reflux ratio control range being 100%-400%.

[0017] Furthermore, the sulfur autotrophic denitrification tank, the first-stage sulfur autotrophic denitrification filter tank, and the second-stage sulfur autotrophic denitrification filter tank are all filled with 3mm of ceramsite filler as a support layer, and ferrous sulfide particles produced by landfill biogas desulfurization as denitrification filter media.

[0018] Furthermore, the anaerobic ammonia oxidation tank is equipped with suspended biofilm packing material to improve stability, with a packing material filling degree of 30%-60%.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention, based on the advantages of existing biochemical treatment, utilizes reduced sulfides generated in landfills as a sulfur source, coupled with anaerobic ammonia oxidation and multi-stage sulfur autotrophic denitrification processes, to achieve full-volume treatment of leachate from aged landfills. It requires no external carbon source, produces no concentrate, and significantly reduces treatment energy consumption and costs. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the zero-carbon-source, zero-concentrate leachate treatment system and method for aged landfills disclosed in this invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, not all embodiments. 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.

[0022] The present invention will now be described in further detail with reference to the accompanying drawings: like Figure 1 As shown, this embodiment of the invention provides a zero-carbon-source, zero-concentrate leachate treatment system for aged landfills, including a sulfur autotrophic denitrification tank 1, a nitrification reaction tank 2, a first sedimentation tank 3, an anaerobic ammonia oxidation tank 4, a second sedimentation tank 5, an intermediate tank 6, a nitrification filter 7, a first-stage sulfur autotrophic denitrification filter 8, a deep treatment system 9, a second-stage sulfur autotrophic denitrification filter 10, a sludge dewatering system 11, a blower 12, and a nutrient dosing system 13.

[0023] The inlet of the sulfur autotrophic denitrification tank 1 receives the filtered leachate from the aged landfill, and its outlet is connected to the inlet of the nitrification reaction tank 2; the outlet of the nitrification reaction tank 2 is connected to the inlet of the first sedimentation tank 3; the outlet of the supernatant from the first sedimentation tank 3 is connected to the inlet of the anaerobic ammonia oxidation tank 4; the outlet of the anaerobic ammonia oxidation tank 4 is connected to the inlet of the second sedimentation tank 5; the outlet of the supernatant from the second sedimentation tank 5 is connected to the inlet of the intermediate tank 6; the intermediate tank 6 is equipped with a return pipeline, which is connected to the inlet of the sulfur autotrophic denitrification tank 1 via a return pump or an air-lift return device; the outlet of the intermediate tank 6 is connected to the inlet of the nitrification filter 7; the outlet of the nitrification filter 7 is connected to the inlet of the first-stage sulfur autotrophic denitrification filter 8; the outlet of the first-stage sulfur autotrophic denitrification filter 8 is connected to... The inlet of the deep treatment system 9 is connected; the outlet of the deep treatment system 9 is connected to the inlet of the second-stage sulfur autotrophic denitrification filter 10, and the outlet of the second-stage sulfur autotrophic denitrification filter 10 is a qualified discharge outlet. The outlet of the deep treatment system 9 is also equipped with an bypass pipeline for direct discharge; the blower 12 is connected to the nitrification reaction tank 2 and the nitrification filter 7 respectively to provide air required for aerobic reaction; the nutrient salt dosing system 13 is connected to the anaerobic ammonia oxidation tank 4 to add nutrients required for microbial growth; the sludge discharge outlets of the first sedimentation tank 3, the second sedimentation tank 5, the nitrification filter 7, the first-stage sulfur autotrophic denitrification filter 8, the deep treatment system 9, and the second-stage sulfur autotrophic denitrification filter 10 are all connected to the sludge dewatering system 11, and the dewatered sludge of the sludge dewatering system 11 is transported off-site for disposal.

[0024] This invention provides a method for treating leachate from aged landfills with zero carbon source and zero concentrate, implemented using the aforementioned system. The specific steps are as follows: Step 1: After being lifted and filtered by the equalization tank lift pump, the leachate from the aged landfill enters the sulfur autotrophic denitrification tank 1. Approximately 3mm of ceramsite filler is added to the sulfur autotrophic denitrification tank 1 as a support layer. Ferrous sulfide particles generated from landfill biogas desulfurization are added as a denitrification sulfur source. Nitrate nitrogen in the return water reacts with ferrous sulfide, converting nitrate nitrogen into nitrogen gas and nitrite nitrogen, completing short-cut denitrification and denitrification treatment. The core reaction equation is as follows: 5FeS + 8NO3 - +8H + →5Fe 3+ +5SO4 2- +4N2↑+4H2O; Fe 2+ +NO3 - +2H + →Fe 3+ +NO2 - +H2O; Step 2: The effluent from the sulfur autotrophic denitrification tank 1 enters the nitrite reaction tank 2. The dissolved oxygen in the nitrite reaction tank 2 is controlled to be 0.3-0.8 mg / L by the blower 12 to maintain the nitrite state in the system. Part of the ammonia nitrogen in the leachate is converted into nitrite nitrogen, which, together with the nitrite nitrogen in the effluent from the sulfur autotrophic denitrification tank 1, serves as the reaction substrate for anaerobic ammonia oxidation.

[0025] Step 3: The effluent from the nitrification reactor 2 enters the first sedimentation tank 3 for sludge-water separation. The nitrate nitrogen concentration in the supernatant is 50-150 mg / L. The separated supernatant then enters the anaerobic ammonia oxidation tank 4. The anaerobic ammonia oxidation tank 4 adopts the biofilm method and adds packing material inside. The packing material is covered with anaerobic ammonia oxidation granular sludge, and the packing material filling degree is 30%-60%. The operating conditions of the anaerobic ammonia oxidation tank 4 are controlled as follows: pH value 7.2-8.3, temperature 28-37℃, dissolved oxygen 0.2-0.8 mg / L. The anaerobic ammonia oxidation bacteria convert ammonia nitrogen and nitrite in the influent into nitrogen gas, achieving ammonia nitrogen removal of more than 90% and total nitrogen removal of more than 80%.

[0026] Step 4: The effluent from the anaerobic ammonia oxidation tank 4 enters the second sedimentation tank 5 for mud-water separation. The second sedimentation tank 5 is preferably an inclined plate sedimentation tank with a hydraulic load of 1~4 m / h. The separated effluent enters the intermediate tank 6 for temporary storage. 50%-80% of the effluent in the intermediate tank 6 is returned to the sulfur autotrophic denitrification tank 1 through a return pump or air lift return device. The return ratio is controlled at 100%-400%. The small amount of nitrate nitrogen in the effluent from the anaerobic ammonia oxidation tank 4 is converted into nitrogen gas and nitrite nitrogen, thus completing the denitrification reaction.

[0027] Step 5: The remaining effluent from the intermediate tank 6 enters the nitrification filter 7, where dissolved oxygen is provided by the blower 12 to convert the remaining ammonia nitrogen in the intermediate tank effluent into nitrate nitrogen. The effluent from the nitrification filter 7 enters the first-stage autotrophic denitrification filter 8, where ferrous sulfide or other sulfides produced by landfill biogas desulfurization are used as reducing agents to reduce the nitrate nitrogen in the influent to nitrogen gas. The remaining recalcitrant COD, ammonia nitrogen, and total nitrogen pollutants are removed through autotrophic denitrification and nitrification. The effluent from the first-stage autotrophic denitrification filter 8 can be partially recycled back to the nitrification filter 7 for further treatment, further improving the pollutant removal rate. Depending on the actual situation of the project, the treatment order of the nitrification filter 7 and the first-stage autotrophic denitrification filter 8 can be reversed, with the autotrophic denitrification filter first and the nitrification filter second, and denitrification circulation achieved by pumping back the effluent.

[0028] Step 6: The effluent from the first-stage sulfur autotrophic denitrification filter 8 enters the advanced treatment system 9 to further remove recalcitrant organic matter, organic nitrogen, total phosphorus, and other pollutants that are difficult to treat by biochemical methods, thereby improving the effluent quality. The advanced treatment system 9 can use advanced catalytic oxidation technologies such as Fenton catalytic oxidation, photocatalytic oxidation, and ozone catalytic oxidation to degrade and remove recalcitrant COD and organic nitrogen. Alternatively, a single-stage or multi-stage material membrane system can be used to remove recalcitrant organic matter and organic nitrogen from the effluent by utilizing the selective retention effect of the material membrane. The concentrated liquid from the material membrane is transported off-site with the sludge for disposal or uniformly reinjected into the landfill. The effluent can stably meet the standards in Table 4 of the "Pollution Control Standard for Municipal Solid Waste Landfills" (GB16889-2024).

[0029] Step 7: The effluent from the deep treatment system 9 enters the second-stage sulfur autotrophic denitrification filter 10 for further denitrification treatment. The effluent can stably meet the standards in Table 2 of the "Pollution Control Standard for Municipal Solid Waste Landfills" (GB16889-2024) before being discharged in compliance with the standards. The effluent from the deep treatment system 9 can also be discharged directly in compliance with the standards through bypass pipelines.

[0030] The sludge generated from step 8, the sulfur autotrophic denitrification tank 1, the nitrification reaction tank 2, the anaerobic ammonia oxidation tank 4, the nitrification filter 7, the first-stage sulfur autotrophic denitrification filter 8, the deep treatment system 9, and the second-stage sulfur autotrophic denitrification filter 10 is discharged into the sludge dewatering system 11 for dewatering treatment. The dewatered sludge is then transported off-site for incineration or disposed of in compliance with regulations.

[0031] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for treating leachate from aged landfills with zero carbon source and zero concentrate, characterized in that, include: Step 1: After being lifted and filtered, the leachate from the old landfill enters the sulfur autotrophic denitrification tank for short-cut denitrification and denitrification treatment; the sulfur autotrophic denitrification tank uses reduced sulfides generated on the landfill as the sulfur source. Step 2: The effluent from the sulfur autotrophic denitrification tank enters the aerobic nitrite reaction tank, where some of the ammonia nitrogen in the leachate is converted into nitrite. Step 3: The effluent from the nitrification reactor enters the first sedimentation tank for mud-water separation. The supernatant after separation enters the anaerobic ammonia oxidation tank, where anaerobic ammonia oxidizing bacteria convert most of the ammonia nitrogen and nitrite in the influent into nitrogen gas. Step 4: The effluent from the anaerobic ammonia oxidation tank enters the second sedimentation tank for mud-water separation. The separated effluent enters the intermediate tank for temporary storage. Part of the effluent from the intermediate tank is returned to the sulfur autotrophic denitrification tank in Step 1 for denitrification and nitrogen removal reaction. Step 5: The remaining effluent from the intermediate tank enters the nitrification filter, and the effluent from the nitrification filter enters the first-stage sulfur autotrophic denitrification filter. The remaining recalcitrant COD, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen pollutants are removed through sulfur autotrophic denitrification and nitrification. The first-stage sulfur autotrophic denitrification filter uses reduced sulfides generated on the landfill as a sulfur source. Step 6: The effluent from the first-stage sulfur autotrophic denitrification filter enters the advanced treatment system to further remove recalcitrant pollutants; Step 7: The effluent from the deep treatment system enters the second-stage sulfur autotrophic denitrification filter and is discharged after treatment to meet the standards; the second-stage sulfur autotrophic denitrification filter uses reduced sulfides generated on the landfill as the sulfur source.

2. The processing method according to claim 1, characterized in that, The sulfur autotrophic denitrification filter material used in the sulfur autotrophic denitrification tank, the first-stage sulfur autotrophic denitrification filter tank, and the second-stage sulfur autotrophic denitrification filter tank is ferrous sulfide particles produced by dry desulfurization of biogas inside the landfill.

3. The processing method according to claim 1, characterized in that, In step 2, the dissolved oxygen in the nitrification reaction tank is controlled at 0.3-0.8 mg / L.

4. The processing method according to claim 1, characterized in that, In step 3, the anaerobic ammonia oxidation tank adopts a biofilm anaerobic ammonia oxidation process with added packing material. The packing material filling degree is 30%-60%, and the operating control conditions are pH value of 7.2-8.3, temperature of 28-37℃, and dissolved oxygen of 0.2-0.8mg / L.

5. The processing method according to claim 1, characterized in that, In step 4, the effluent from the intermediate tank is returned to the sulfur autotrophic denitrification tank at a rate of 100%-400%.

6. The processing method according to claim 1, characterized in that, In step 5, the treatment order of the nitrification filter and the first-stage sulfur autotrophic denitrification filter is reversed, with the first-stage sulfur autotrophic denitrification filter preceding the nitrification filter, and denitrification is achieved through pump reflux.

7. The processing method according to claim 1, characterized in that, In step 6, the deep processing system is an advanced catalytic oxidation system and / or a special material separation membrane system; the advanced catalytic oxidation system is one or more of Fenton catalytic oxidation, ultraviolet photocatalytic oxidation, and ozone catalytic oxidation; the special material separation membrane system is a single-stage or multi-stage material membrane system with a molecular weight cutoff of 200-10000 Da.

8. The processing method according to claim 1, characterized in that, Also includes: Step 8: Discharge all sludge produced by each level of pool or system into the sludge dewatering system, and transport it off-site for disposal after dewatering.

9. A zero-carbon-source, zero-concentrate leachate treatment system for aged landfills, used to implement the treatment method as described in any one of claims 1-5 or 7-8, characterized in that, It includes a sulfur autotrophic denitrification tank, a nitrification reaction tank, a first sedimentation tank, an anaerobic ammonia oxidation tank, a second sedimentation tank, an intermediate tank, a nitrification filter, a first-stage sulfur autotrophic denitrification filter, a deep treatment system, and a second-stage sulfur autotrophic denitrification filter, which are connected sequentially along the water flow direction; the intermediate tank is equipped with a return pipeline, and the outlet end of the return pipeline is connected to the inlet end of the sulfur autotrophic denitrification tank.

10. The processing system according to claim 9, characterized in that, Also includes: Sludge dewatering system; The sludge discharge outlets of the first sedimentation tank, the second sedimentation tank, the nitrification filter, the first-stage sulfur autotrophic denitrification filter, the deep treatment system, and the second-stage sulfur autotrophic denitrification filter are all connected to the sludge dewatering system.

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