Anaerobic-aerobic-anoxic system for in-situ enrichment of pyrite denitrification and anaerobic ammonium oxidation bacteria and control method of anaerobic-aerobic-anoxic system

Abstract

The invention belongs to the technical field of domestic sewage treatment, and particularly discloses an anaerobic-aerobic-anoxic system for in-situ enrichment of pyrite denitrification and anaerobic ammonium oxidation bacteria and a control method of the anaerobic-aerobic-anoxic system. The method is used for solving the problem that anaerobic ammonium oxidation bacteria and ferrous sulfide denitrifying bacteria are difficult to enrich. The retention time of the anaerobic zone is regulated in real time, full storage of a limited carbon source of raw water is achieved, meanwhile, the dissolved oxygen and nitrification degree of the aerobic zone is monitored and regulated, finally, nitrite is provided through endogenous short-cut denitrification in the front anoxic zone, anaerobic ammonium oxidation bacteria enrichment is achieved, generated nitrate enters the rear anoxic zone, and the anaerobic ammonium oxidation bacteria are enriched. Under the driving of the ferrous sulfide functional filter material, the enrichment of ferrous sulfide denitrifying bacteria is realized. Through cooperation of the front anoxic zone and the rear anoxic zone, low-carbon deep denitrification of domestic sewage is realized, meanwhile, the concentration change of sulfide is monitored in real time in the rear anoxic zone, and oxygen-limited aeration is performed to oxidize the sulfide into elemental sulfur, so that cyclic utilization of a sulfur-iron functional filter material is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of domestic sewage treatment, and in particular relates to an anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria and a control method thereof. Background Art

[0003] Anaerobic ammonium oxidation is a new type of autotrophic denitrification process that does not require an external carbon source and can achieve the synergistic removal of ammonia nitrogen and nitrite under anaerobic conditions. However, it will produce nitrate byproducts, which limits the improvement of the denitrification efficiency of anaerobic ammonium oxidation. Sulfur-iron autotrophic denitrification uses reduced sulfur and iron as electron donors to achieve deep nitrate removal in the absence of an external carbon source, but its ability to remove ammonia nitrogen is limited. If anaerobic ammonium oxidation and sulfur-iron autotrophic denitrification can be combined, low-carbon deep denitrification can be achieved, and the theoretical denitrification efficiency can reach 100%. However, the growth of anaerobic ammonium oxidizing bacteria and sulfur-iron denitrifying bacteria has high environmental requirements, and it is difficult to enrich the bacterial community. Summary of the invention

[0004] One object of the present invention is to provide an anaerobic-aerobic-anoxic system for in-situ enrichment of ferrosulfur denitrifying and anaerobic ammonia oxidizing bacteria, which effectively solves the problem that the flora of anaerobic ammonia oxidizing bacteria and ferrosulfur denitrifying bacteria are difficult to enrich.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] An anaerobic-aerobic-anoxic system for in-situ enrichment of sulfide-iron denitrification and anaerobic ammonia-oxidizing bacteria comprises a combined real-time monitoring and control system, a dissolved oxygen real-time monitoring and control system, a sulfide real-time monitoring and control system, a water inlet unit, an anaerobic-aerobic-anoxic unit and a water outlet unit, wherein the water inlet unit comprises a water inlet tank, a water inlet pipe and a water inlet pump, the anaerobic-aerobic-anoxic unit is a rectangular plug-flow continuous flow system, the anaerobic-aerobic-anoxic unit comprises an anaerobic zone, an aerobic zone, a front anoxic zone and a rear anoxic zone which are sequentially connected according to the water flow direction, and the water outlet unit comprises a water outlet pump and a water outlet tank.

[0007] A COD monitoring probe is provided at the rear end of the anaerobic zone, a total nitrogen detection probe is provided at the front end of the aerobic zone, and an ammonia nitrogen monitoring probe is provided at the rear end of the aerobic zone. The water inlet pump, COD monitoring probe, total nitrogen detection probe and ammonia nitrogen monitoring probe are all connected to a joint real-time monitoring and control system.

[0008] The aerobic zone is also provided with a dissolved oxygen monitoring probe and an aeration device. The aeration device includes a gas flow meter for controlling the aeration amount. The dissolved oxygen monitoring probe and the gas flow meter are both connected to a dissolved oxygen real-time monitoring and control system.

[0009] The anaerobic zone, aerobic zone and front anoxic zone are all provided with fixed filler balls, the rear anoxic zone is provided with sulfur-based filter material, iron-based filter material, a sulfide monitoring probe and a backwashing device, the backwashing device includes a backwashing air pump for controlling the gas flow rate and a backwashing water pump for controlling the water volume, and the sulfide monitoring probe, backwashing air pump and backwashing water pump are all connected to the sulfide real-time monitoring and control system.

[0010] Furthermore, the volume ratio of the anaerobic zone, the aerobic zone, the pre-anoxic zone and the post-anoxic zone is 2:2:3:3.

[0011] Furthermore, the sulfur-based filter material and the iron-based filter material are both spherical filter materials with a diameter of 3 to 4 mm. The sulfur-based filter material and the iron-based filter material are mixed in a ratio of 4:1 and then filled into the rear anoxic zone at a filling ratio of 100%.

[0012] Furthermore, the aeration device also includes a blower and a microporous aeration disk, the outlet of the blower is connected to the inlet of a gas flow meter, the outlet of the gas flow meter is connected to the inlet of the microporous aeration disk, and the microporous aeration disk is arranged at the bottom of the aerobic zone.

[0013] Furthermore, the backwash device also includes a backwash water tank, the outlet of the backwash water tank is connected to the inlet of the backwash water pump, and the outlet of the backwash water pump and the outlet of the backwash air pump are both connected to the rear anoxic zone through a pipeline.

[0014] Furthermore, a water inlet is provided at the front end of the anaerobic zone, the outlet of the water inlet tank is connected to the inlet of a water inlet pump, and the outlet of the water inlet pump is connected to the water inlet through a water inlet pipe.

[0015] A water outlet is provided at the upper part of the rear end of the rear anoxic zone, and the water outlet is connected to the inlet of a water outlet pump through a first water outlet pipe, the outlet of the water outlet pump is connected to the inlet of a water outlet tank, and the water outlet is connected to the inlet of a backwash water tank through a second water outlet pipe.

[0016] Another object of the present invention is to provide a control method for the anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria as described in the above embodiments, comprising the following steps: S1, the sewage in the water inlet tank is pumped into the anaerobic zone through the water inlet pump, the organic carbon source in the sewage is used by heterotrophic denitrifying bacteria to remove nitrate in the sewage, and the unused organic carbon source is stored as an internal carbon source by endogenous denitrifying bacteria, and the COD monitoring probe monitors the COD concentration at the rear end of the anaerobic zone in real time. When the COD concentration is >10 mg / L, the combined real-time monitoring and control system controls the water inlet pump to reduce the water flow rate; when the COD concentration is ≤10 mg / L, the organic carbon source is effectively stored.

[0017] S2. Then the sewage enters the aerobic zone, and the aeration device is started for aeration to convert the ammonia nitrogen in the sewage into nitrate. The dissolved oxygen monitoring probe transmits the dissolved oxygen concentration in real time to the dissolved oxygen real-time monitoring and control system. When the dissolved oxygen concentration is >1.0mg / L, the dissolved oxygen real-time monitoring and control system controls the gas flow meter to reduce the gas flow; when the dissolved oxygen concentration is <1.0mg / L, the dissolved oxygen real-time monitoring and control system controls the gas flow meter to increase the gas flow, and finally stabilizes the dissolved oxygen concentration in the aerobic zone at 0.8~1.0mg / L.

[0018] The total nitrogen monitoring probe and the ammonia nitrogen monitoring probe transmit the monitoring data to the joint real-time monitoring and control system in real time. Assuming that the total nitrogen concentration at the front end of the aerobic zone monitored by the total nitrogen monitoring probe is a mg / L, and the ammonia nitrogen concentration at the rear end of the aerobic zone monitored by the ammonia nitrogen monitoring probe is b mg / L, when b / a>0.43, the joint real-time monitoring and control system controls the water inlet pump to reduce the water inlet flow rate; when b / a<0.43, the joint real-time monitoring and control system controls the water inlet pump to increase the water inlet flow rate to ensure the supply of ammonia nitrogen and nitrite to the front anoxic zone.

[0019] S3. The sewage continues to flow to the front anoxic zone. Endogenous denitrifying bacteria use the internal carbon source stored in the anaerobic zone to drive short-range denitrification to produce nitrite. Ammonia nitrogen and nitrite provide substrates for anaerobic ammonium oxidizing bacteria, thereby domesticating anaerobic ammonium oxidizing bacteria and producing nitrate at the same time.

[0020] S4. When the sewage enters the post-anoxic zone, the nitrate produced in the pre-anoxic zone and the sulfur-based filter material and the iron-based filter material serve as substrates for sulfide-iron denitrifying bacteria, gradually enriching the sulfide-iron denitrifying bacteria to remove the remaining nitrate, thereby achieving deep denitrification.

[0021] The post-anoxic zone produces sulfate through autotrophic denitrification of sulfide and iron, thereby enriching sulfate-reducing bacteria and causing part of the sulfate to be reduced to sulfide. The sulfide monitoring probe transmits the sulfide concentration in the post-anoxic zone to the sulfide real-time monitoring and control system in real time. When the sulfide concentration is >7mg / L, the backwash air pump and backwash water pump are started, and the gas and water volumes are controlled to be 1000mL / min and 500mL / min respectively; when the sulfide concentration is ≤7mg / L, the backwash air pump and backwash water pump are turned off.

[0022] S5. Finally, the treated sewage enters the outlet tank through the outlet pump.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] (1) The present invention realizes deep denitrification by anaerobic ammonia oxidation and sulfide-iron autotrophic denitrification, with a denitrification efficiency of more than 95%, without the need for adding an external carbon source, reducing sludge production by 80% and power consumption by 60%.

[0025] (2) The present invention controls the COD concentration in the anaerobic zone to be ≤10 mg / L and the ratio of the ammonia nitrogen concentration at the rear end to the total nitrogen concentration at the front end of the aerobic zone to be 0.43 according to the high and low loads of the influent and the degree of nitrification, so that the organic carbon source in the anaerobic zone is effectively stored and the aerobic zone is partially nitrified, providing a substrate for anaerobic ammonia oxidation, and realizing in situ enrichment of anaerobic ammonia-oxidizing bacteria with an enrichment time of less than 60 days.

[0026] (3) The present invention, driven by the sulfide-iron functional filter material and combined with the oxygen-limited aeration strategy, achieves in-situ enrichment of sulfide-iron denitrifying bacteria with an enrichment time of less than 35 days, and simultaneously achieves sulfide oxidation, reducing the sulfate concentration by 80%, effectively realizing the recycling of sulfur sources, reducing sulfide-iron source consumption by 55%, and saving sulfide-iron sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the connection structure of the anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria of the present invention.

[0028] Figure 2 It is a system control flow chart for realizing low-carbon denitrification according to the present invention, wherein the solid line represents the operation process and the dotted line represents the control process.

[0029] List of reference numerals: combined real-time monitoring and control system-1; dissolved oxygen real-time monitoring and control system-2; sulfide real-time monitoring and control system-3; water inlet tank-4; water inlet pipe-5; water inlet pump-6; anaerobic zone-7; aerobic zone-8; front anoxic zone-9; rear anoxic zone-10; water outlet pump-12; water outlet tank-13; COD monitoring probe-14; total nitrogen detection probe-15; ammonia nitrogen monitoring probe-16; dissolved oxygen monitoring probe-17; blower-18; microporous aeration disk-19; gas flowmeter-20; fixed filler ball-21; sulfur-based filter material-22; iron-based filter material-23; sulfide monitoring probe-24; backwash water tank-25; backwash air pump-26; backwash water pump-27. DETAILED DESCRIPTION

[0030] Example 1: An anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria, such as Figure 1 As shown, it includes a combined real-time monitoring and control system 1, a dissolved oxygen real-time monitoring and control system 2, a sulfide real-time monitoring and control system 3, an inlet unit, an anaerobic-aerobic-anoxic unit and an outlet unit. The inlet unit includes an inlet tank 4, an inlet pipe 5 and an inlet pump 6. The anaerobic-aerobic-anoxic unit is a rectangular plug-flow continuous flow system. The anaerobic-aerobic-anoxic unit includes an anaerobic zone 7, an aerobic zone 8, a front anoxic zone 9 and a rear anoxic zone 10 which are sequentially connected according to the direction of water flow. The volume ratio of the anaerobic zone 7, the aerobic zone 8, the front anoxic zone 9 and the rear anoxic zone 10 is 2:2:3:3. The outlet unit includes an outlet pump 12 and an outlet tank 13.

[0031] A water inlet is provided at the front end of the anaerobic zone 7, the outlet of the water inlet tank 4 is connected to the inlet of the water inlet pump 6, and the outlet of the water inlet pump 6 is connected to the water inlet through the water inlet pipe 5. A water outlet is provided at the upper part of the rear end of the post-anoxic zone 10, and the water outlet is connected to the inlet of the water outlet pump 12 through the first water outlet pipe, and the outlet of the water outlet pump 12 is connected to the inlet of the water outlet tank 13.

[0032] A COD monitoring probe 14 is provided at the rear end of the anaerobic zone 7. A total nitrogen detection probe 15 is provided at the front end of the aerobic zone 8, and an ammonia nitrogen monitoring probe 16 is provided at the rear end of the aerobic zone 8. The water inlet pump 6, the COD monitoring probe 14, the total nitrogen detection probe 15 and the ammonia nitrogen monitoring probe 16 are all connected to the joint real-time monitoring and control system 1.

[0033] A dissolved oxygen monitoring probe 17 and an aeration device are also provided in the aerobic zone 8. The aeration device includes a blower 18, a microporous aeration disk 19, and a gas flow meter 20 for controlling the aeration amount. The outlet of the blower 18 is connected to the inlet of the gas flow meter 20, and the outlet of the gas flow meter 20 is connected to the inlet of the microporous aeration disk 19. The microporous aeration disk 19 is provided at the bottom of the aerobic zone 8 to provide dissolved oxygen. The dissolved oxygen monitoring probe 17 and the gas flow meter 20 are both connected to the dissolved oxygen real-time monitoring and control system 2.

[0034] Fixed filler balls 21 are evenly arranged in the anaerobic zone 7, the aerobic zone 8 and the front anoxic zone 9, and sulfur-based filter materials 22 and iron-based filter materials 23 are arranged in the rear anoxic zone 10. The sulfur-based filter materials 22 and the iron-based filter materials 23 are both spherical filter materials with a diameter of 3 to 4 mm. The sulfur-based filter materials 22 and the iron-based filter materials 23 are mixed in a ratio of 4:1 and filled into the rear anoxic zone 10 at a filling ratio of 100%.

[0035] A sulfide monitoring probe 24 and a backwashing device are also provided in the post-anoxic zone 10. The backwashing device includes a backwashing water tank 25, a backwashing air pump 26 for controlling the gas flow rate, and a backwashing water pump 27 for controlling the water volume. The water outlet is connected to the inlet of the backwashing water tank 25 through a second water outlet pipe, and the water used for backwashing of the anaerobic-aerobic-anoxic system is generally the outlet water of the anaerobic-aerobic-anoxic system. The outlet of the backwashing water tank 25 is connected to the inlet of the backwashing water pump 27, and the outlet of the backwashing water pump 27 and the outlet of the backwashing air pump 26 are both connected to the post-anoxic zone 10 through a pipeline intersection, so that backwashing and oxygen-limited aeration can be achieved at the same time to prevent the aeration volume from being too high. The sulfide monitoring probe 24, the backwashing air pump 26, and the backwashing water pump 27 are all connected to the sulfide real-time monitoring and control system 3.

[0036] Example 2: This example aims to determine the key control parameters of the residence time and nitrification process of the anaerobic zone 7 and the aerobic zone 8 according to the water quality of common low-load and high-load domestic sewage, so as to achieve a stable supply of nitrite in the front anoxic zone 9, and then achieve rapid enrichment of anaerobic ammonia oxidizing bacteria. Through the sulfide-iron functional filter material, the sulfide-iron denitrifying bacteria are enriched in situ in the rear anoxic zone 10, and the sulfide-iron autotrophic denitrification and anaerobic ammonia oxidation are coordinated to achieve low-carbon deep nitrogen removal. The sulfide produced by sulfate-reducing bacteria is converted into elemental sulfur through oxygen-limited aeration, which circulates to provide electrons and reduce the consumption of sulfide-iron functional filter material, thereby achieving the enrichment of sulfide-iron denitrifying bacteria and its functional coordination with sulfate-reducing bacteria.

[0037] Specifically, a method for controlling an anaerobic-aerobic-anoxic system for in situ enrichment of ferrous sulfide denitrification and anaerobic ammonia-oxidizing bacteria as described in Example 1. The anaerobic-aerobic-anoxic system provided in this embodiment can be started by inoculating residual sludge from the secondary sedimentation tank of a municipal sewage treatment plant, with low-load or high-load domestic sewage as the influent, mainly containing COD (100-400 mg / L), ammonia nitrogen (20-120 mg / L) and total nitrogen (30-130 mg / L).

[0038] like Figure 2 As shown, the following steps are included: (1) The sewage in the water inlet tank 4 is pumped into the anaerobic zone 7 through the water inlet pump 6, and the organic carbon source in the sewage can be used by heterotrophic denitrifying bacteria to remove nitrates in the sewage, and the unused organic carbon source can be stored as an internal carbon source by endogenous denitrifying bacteria. The COD monitoring probe 14 monitors the COD concentration at the rear end of the anaerobic zone 7 in real time. When the COD concentration is >10mg / L, the combined real-time monitoring and control system 1 controls the water inlet pump 6 to reduce the water flow rate; when the COD concentration is ≤10mg / L, the organic carbon source is effectively stored.

[0039] (2) Then the sewage enters the aerobic zone 8, and the blower 18 is started for aeration to convert the ammonia nitrogen in the sewage into nitrate. The dissolved oxygen monitoring probe 17 transmits the dissolved oxygen concentration in real time to the dissolved oxygen real-time monitoring and control system 2. When the dissolved oxygen concentration is greater than 1.0 mg / L, the dissolved oxygen real-time monitoring and control system 2 controls the gas flow meter 20 to reduce the gas flow; when the dissolved oxygen concentration is less than 1.0 mg / L, the dissolved oxygen real-time monitoring and control system 2 controls the gas flow meter 20 to increase the gas flow, and finally stabilizes the dissolved oxygen concentration in the aerobic zone 8 at 0.8-1.0 mg / L.

[0040] The total nitrogen monitoring probe 15 at the front end of the aerobic zone 8 and the ammonia nitrogen monitoring probe 16 at the rear end of the aerobic zone 8 transmit the monitoring data in real time to the joint real-time monitoring and control system 1. Assuming that the total nitrogen concentration at the front end of the aerobic zone 8 monitored by the total nitrogen monitoring probe 15 is amg / L, and the ammonia nitrogen concentration at the rear end of the aerobic zone 8 monitored by the ammonia nitrogen monitoring probe 16 is b mg / L, when b / a>0.43, the joint real-time monitoring and control system 1 controls the water inlet pump 6 to reduce the water inlet flow rate; when b / a<0.43, the joint real-time monitoring and control system 1 controls the water inlet pump 6 to increase the water inlet flow rate to ensure that ammonia nitrogen and nitrite are provided to the front anoxic zone 9.

[0041] (3) The sewage continues to flow to the front anoxic zone 9. The endogenous denitrifying bacteria use the internal carbon source stored in the anaerobic zone 7 to drive short-range denitrification to produce nitrite. Ammonia nitrogen and nitrite can provide substrates for anaerobic ammonium oxidizing bacteria, thereby domesticating anaerobic ammonium oxidizing bacteria and producing nitrate at the same time.

[0042] (4) After the sewage enters the post-anoxic zone 10, the nitrate produced in the pre-anoxic zone 9 and the sulfur-based filter material and the iron-based filter material can serve as substrates for sulfide-iron denitrifying bacteria, gradually enriching the sulfide-iron denitrifying bacteria to remove the remaining nitrate, thereby achieving deep denitrification.

[0043] The post-anoxic zone 10 produces sulfate (90-120 mg / L) through ferrosulphide autotrophic denitrification, so that sulfate-reducing bacteria will be enriched, resulting in the reduction of part of the sulfate to sulfide (5-20 mg / L). The sulfide monitoring probe 24 transmits the sulfide concentration of the post-anoxic zone 10 to the sulfide real-time monitoring and control system 3 in real time. When the sulfide concentration is >7 mg / L, the backwashing air pump 26 and the backwashing water pump 27 are started, and the gas flow rate and water flow rate are controlled to 1000 mL / min and 500 mL / min respectively, and the sulfide is oxidized to sulfur element, thereby promoting the continuous sulfate reduction process, continuously providing sulfur sources for ferrosulphide autotrophic denitrification to reduce the consumption of ferrosulphide functional filter materials. When the sulfide concentration is ≤7 mg / L, the backwashing air pump 26 and the backwashing water pump 27 are turned off.

[0044] (5) Finally, the treated sewage enters the outlet tank 13 through the outlet pump 12.

[0045] This embodiment achieves deep denitrification by anaerobic ammonia oxidation and sulfide-iron autotrophic denitrification, with a denitrification efficiency of more than 95%, without the need for adding an external carbon source, reducing sludge production by 80% and electricity consumption by 60%.

[0046] In this embodiment, according to the high and low loads of the influent and the degree of nitrification, the COD concentration in the anaerobic zone is controlled to be ≤10 mg / L and the ratio of the rear end ammonia nitrogen concentration to the front end total nitrogen concentration in the aerobic zone is controlled to be 0.43, so that the organic carbon source in the anaerobic zone is effectively stored and the aerobic zone is partially nitrified, providing a substrate for anaerobic ammonia oxidation, and realizing in situ enrichment of anaerobic ammonia oxidizing bacteria with an enrichment time of less than 60 days.

[0047] Driven by the sulfide-iron functional filter material, this embodiment combines the oxygen-limited aeration strategy to achieve in-situ enrichment of sulfide-iron denitrifying bacteria with an enrichment time of less than 35 days, while achieving sulfide oxidation, reducing the sulfate concentration by 80%, effectively realizing the recycling of sulfur sources, reducing sulfide-iron source consumption by 55%, and saving sulfide-iron sources.

[0048] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria, characterized in that: It includes a combined real-time monitoring and control system, a dissolved oxygen real-time monitoring and control system, a sulfide real-time monitoring and control system, a water inlet unit, an anaerobic-aerobic-anoxic unit and a water outlet unit, wherein the water inlet unit includes a water inlet tank, a water inlet pipe and a water inlet pump, the anaerobic-aerobic-anoxic unit is a rectangular plug-flow continuous flow system, the anaerobic-aerobic-anoxic unit includes an anaerobic zone, an aerobic zone, a front anoxic zone and a rear anoxic zone which are sequentially connected according to the water flow direction, and the water outlet unit includes a water outlet pump and a water outlet tank; The rear end of the anaerobic zone is provided with a COD monitoring probe, the front end of the aerobic zone is provided with a total nitrogen detection probe, and the rear end of the aerobic zone is provided with an ammonia nitrogen monitoring probe. The water inlet pump, COD monitoring probe, total nitrogen detection probe and ammonia nitrogen monitoring probe are all connected to a joint real-time monitoring and control system; The aerobic zone is also provided with a dissolved oxygen monitoring probe and an aeration device, the aeration device includes a gas flow meter for controlling the aeration amount, and the dissolved oxygen monitoring probe and the gas flow meter are both connected to a dissolved oxygen real-time monitoring and control system; The anaerobic zone, aerobic zone and front anoxic zone are all provided with fixed filler balls, the rear anoxic zone is provided with sulfur-based filter material, iron-based filter material, a sulfide monitoring probe and a backwashing device, the backwashing device includes a backwashing air pump for controlling the gas flow rate and a backwashing water pump for controlling the water volume, and the sulfide monitoring probe, backwashing air pump and backwashing water pump are all connected to the sulfide real-time monitoring and control system.

2. The anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria according to claim 1, characterized in that: The volume ratio of the anaerobic zone, the aerobic zone, the pre-anoxic zone and the post-anoxic zone is 2:2:3:

3.

3. The anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria according to claim 2, characterized in that: The sulfur-based filter material and the iron-based filter material are both spherical filter materials with a diameter of 3 to 4 mm. The sulfur-based filter material and the iron-based filter material are mixed in a ratio of 4:1 and then filled into the rear anoxic zone at a filling ratio of 100%.

4. The anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria according to claim 3, characterized in that: The aeration device also includes a blower and a microporous aeration disk. The outlet of the blower is connected to the inlet of a gas flow meter. The outlet of the gas flow meter is connected to the inlet of the microporous aeration disk. The microporous aeration disk is arranged at the bottom of the aerobic zone.

5. The anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria according to claim 4, characterized in that: The backwash device also includes a backwash water tank, the outlet of the backwash water tank is connected to the inlet of the backwash water pump, and the outlet of the backwash water pump and the outlet of the backwash air pump are both connected to the rear anoxic zone through a pipeline intersection.

6. The anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria according to claim 5, characterized in that: A water inlet is provided at the front end of the anaerobic zone, the outlet of the water inlet tank is connected to the inlet of the water inlet pump, and the outlet of the water inlet pump is connected to the water inlet through a water inlet pipe; A water outlet is provided at the upper part of the rear end of the rear anoxic zone, and the water outlet is connected to the inlet of a water outlet pump through a first water outlet pipe, the outlet of the water outlet pump is connected to the inlet of a water outlet tank, and the water outlet is connected to the inlet of a backwash water tank through a second water outlet pipe.

7. A method for controlling an anaerobic-aerobic-anoxic system for in-situ enrichment of ferrous sulfide denitrification and anaerobic ammonia oxidizing bacteria according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. The sewage in the water inlet tank is pumped into the anaerobic zone through the water inlet pump. The organic carbon source in the sewage is used by heterotrophic denitrifying bacteria to remove nitrates in the sewage. The unused organic carbon source is stored as an internal carbon source by endogenous denitrifying bacteria. The COD monitoring probe monitors the COD concentration at the rear end of the anaerobic zone in real time. When the COD concentration is >10mg / L, the combined real-time monitoring and control system controls the water inlet pump to reduce the water flow rate; when the COD concentration is ≤10mg / L, the organic carbon source is effectively stored; S2. Then the sewage enters the aerobic zone, and the aeration device is started for aeration to convert the ammonia nitrogen in the sewage into nitrate. The dissolved oxygen monitoring probe transmits the dissolved oxygen concentration to the dissolved oxygen real-time monitoring and control system in real time. When the dissolved oxygen concentration is >1.0mg / L, the dissolved oxygen real-time monitoring and control system controls the gas flow meter to reduce the gas flow; when the dissolved oxygen concentration is <1.0mg / L, the dissolved oxygen real-time monitoring and control system controls the gas flow meter to increase the gas flow, and finally stabilizes the dissolved oxygen concentration in the aerobic zone at 0.8-1.0mg / L. The total nitrogen monitoring probe and the ammonia nitrogen monitoring probe transmit the monitoring data to the joint real-time monitoring and control system in real time. Assuming that the total nitrogen concentration at the front end of the aerobic zone monitored by the total nitrogen monitoring probe is a mg / L, and the ammonia nitrogen concentration at the rear end of the aerobic zone monitored by the ammonia nitrogen monitoring probe is b mg / L, when b / a>0.43, the joint real-time monitoring and control system controls the water inlet pump to reduce the water inlet flow rate; when b / a<0.43, the joint real-time monitoring and control system controls the water inlet pump to increase the water inlet flow rate to ensure the supply of ammonia nitrogen and nitrite to the front anoxic zone; S3, the sewage continues to flow to the front anoxic zone, and the endogenous denitrifying bacteria use the internal carbon source stored in the anaerobic zone to drive short-range denitrification to produce nitrite. Ammonia nitrogen and nitrite provide substrates for anaerobic ammonium oxidizing bacteria, thereby domesticating anaerobic ammonium oxidizing bacteria and producing nitrate at the same time; S4, sewage enters the post-anoxic zone, the nitrate produced in the pre-anoxic zone and the sulfur-based filter material and the iron-based filter material serve as substrates for sulfide-iron denitrifying bacteria, gradually enriching sulfide-iron denitrifying bacteria to remove the remaining nitrate, thereby achieving deep denitrification; The post-anoxic zone produces sulfate through autotrophic denitrification of pyrite, thereby enriching sulfate-reducing bacteria and reducing part of the sulfate to sulfide. The sulfide monitoring probe transmits the sulfide concentration in the post-anoxic zone to the sulfide real-time monitoring and control system in real time. When the sulfide concentration is >7mg / L, the backwash air pump and backwash water pump are started, and the air and water volumes are controlled to be 1000mL / min and 500mL / min respectively; when the sulfide concentration is ≤7mg / L, the backwash air pump and backwash water pump are turned off; S5. Finally, the treated sewage enters the outlet tank through the outlet pump.

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