Anaerobic ammonia oxidation reaction system

Abstract

The utility model provides an anaerobic ammonia oxidation reaction system. The reaction system comprises a wastewater treatment system, the wastewater treatment system comprises: a first reactor for removing nitrate nitrogen in wastewater and producing first treated water; the second reactor is used for removing ammonia nitrogen and nitrite nitrogen in the first treated water and producing second treated water; the third reactor is used for adjusting the nitrogen composition and concentration of the second treated water and producing third treated water; and the fourth reactor is used for reducing nitrate nitrogen in the third treated water into nitrogen so as to reduce the concentration of total nitrogen in the effluent. The utility model solves the technical problems that an anaerobic ammonia oxidation water treatment system adopting a traditional activated sludge process is insufficient in total nitrogen treatment capacity during operation, and particularly cannot effectively remove nitrate nitrogen in an anaerobic ammonia oxidation reaction product; in the prior art, the treated water can still contain a certain amount of nitrogen pollutants and cannot meet the requirements of discharged water quality.

Description

Technical Field

[0001] The utility model relates to the technical field of sewage treatment, in particular to an anaerobic ammonia oxidation reaction system. Background Art

[0002] With the country's increasing emphasis on energy conservation and emission reduction, wastewater treatment companies, under pressure from industry development, are also facing higher requirements for controlling unit consumption of wastewater treatment. Wastewater denitrification processes, especially those with high ammonia nitrogen content and low carbon-nitrogen ratios, require high total nitrogen removal rates and minimized operating costs per ton of water. This necessitates the use of processes with minimal operating costs.

[0003] Therefore, there is at least one problem in the relevant technology: during the operation period of the anaerobic ammonium oxidation water treatment system using the traditional activated sludge process, the total nitrogen treatment capacity is insufficient, especially the nitrate nitrogen in the anaerobic ammonium oxidation reaction products cannot be effectively removed, which easily leads to the treated water still containing a certain amount of nitrogen pollutants and failing to meet the discharge water quality requirements. Utility Model Content

[0004] The technical problem solved by the utility model is that during the operation period of the anaerobic ammonium oxidation water treatment system using the traditional activated sludge process, the total nitrogen treatment capacity is insufficient, especially the nitrate nitrogen in the anaerobic ammonium oxidation reaction products cannot be effectively removed, which easily leads to the possibility that the treated water still contains a certain amount of nitrogen pollutants and cannot meet the discharge water quality requirements.

[0005] To solve the above problems, the utility model provides an anaerobic ammonium oxidation reaction system, which includes a wastewater treatment system; the wastewater treatment system includes: a first reactor, used to remove nitrate nitrogen in the wastewater and produce first treated water; a second reactor, the second reactor is arranged on one side of the first reactor, used to remove ammonia nitrogen and nitrite nitrogen in the first treated water, and produce second treated water; a third reactor, the third reactor is arranged on a side of the second reactor away from the first reactor, used to adjust the nitrogen composition and concentration of the second treated water, and produce third treated water; a fourth reactor, the fourth reactor is arranged on a side of the third reactor away from the second reactor, used to reduce nitrate nitrogen in the treated water to nitrogen gas to reduce the concentration of total nitrogen in the effluent; wherein the first reactor, the second reactor, the third reactor and the fourth reactor are connected in sequence by pipelines; the first reactor includes a denitrification biofilm reactor, the second reactor includes an anaerobic ammonium oxidation biofilm reactor, the third reactor includes a short-range nitrification biofilm reactor and the fourth reactor includes a sulfur autotrophic denitrification reactor.

[0006] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: compared with the activated sludge technology adopted in the related technology, the present application adopts the synergistic effect of multiple biofilm reactors, and reduces the nitrate nitrogen in the third treated water produced in the third reactor into nitrogen gas by adding a fourth reactor at the rear end of the third reactor, so as to effectively reduce the total nitrogen concentration of the effluent and solve the problem of excessive total nitrogen content in the treated water; and, the activated sludge technology in the related technology can only cultivate one bacterial species at a time, and the bacterial species have poor stability and are easily disturbed by external factors. The present application adopts a biofilm process, and each biofilm reactor can cultivate its corresponding bacterial species at the same time, which greatly reduces the startup time of the wastewater treatment system. Since each reactor only needs to cultivate its corresponding bacterial species, the bacterial species culture environment is stable and not easily disturbed by external factors; on the other hand, the fourth reactor can not only solve the problem of insufficient total nitrogen treatment, but also reduce the supply of carbon source.

[0007] In one embodiment of the present invention, biofilm fillers are installed inside the first reactor, the second reactor, the third reactor and the fourth reactor; the biofilm fillers are braided or sheet-type.

[0008] Compared with the existing technology, the technical effect achieved by adopting this technical solution is: by installing biofilm fillers in each reactor to cultivate a single bacterial species, the bacterial species cultivation efficiency is improved, and the interference between the various bacterial species is also reduced.

[0009] In one embodiment of the present invention, aerators are provided at the bottom of the first reactor, the second reactor, the third reactor and the fourth reactor.

[0010] Compared with the existing technology, the technical effect achieved by adopting this technical solution is: providing oxygen and stirring effects for each reactor, making the wastewater and sludge mixed more evenly and improving the reaction efficiency.

[0011] In one embodiment of the present invention, the fourth reactor is filled with sulfur autotrophic filler for cultivating sulfur autotrophic bacteria.

[0012] Compared with the existing technology, the technical effects achieved by adopting this technical solution are: filling sulfur autotrophic fillers, cultivating sulfur autotrophic bacteria, improving the nitrate nitrogen reduction ability, and further reducing the total nitrogen concentration in the effluent.

[0013] In one embodiment of the present invention, it also includes: multiple control valves; the control valve is arranged between any two reactors, and is used to control the communication between the reactors; wherein, by opening the control valve, the wastewater treatment system forms a first loop; by closing the control valve, the wastewater treatment system is switched from the first loop to the second loop.

[0014] Compared with the existing technology, the technical effect achieved by adopting this technical solution is: due to the differences in the cultivation time of the bacterial strains in each reactor, the wastewater treatment system can be separated into the first loop and the second loop through the control valve to improve the flexibility of the entire system.

[0015] In one example of the present invention, the first loop is formed by the first reactor, the second reactor, the third reactor and the fourth reactor being connected in sequence through pipes, and the wastewater treatment system is in the operation stage; the second loop is formed by the first reactor, the third reactor and the fourth reactor being connected in sequence through pipes, so that the second reactor operates alone, and the wastewater treatment system is in the debugging stage.

[0016] Compared with the existing technology, the technical effect achieved by adopting this technical solution is: since the cultivation time of the bacterial species in the second reactor is longer than that of the other three reactors, the second reactor is operated alone to prevent the immature biofilm from falling off the filler; when the biofilm in the second reactor is cultured to maturity, it is connected to the second loop through the control valve to form the first loop. At this time, the wastewater treatment system is in the normal operation stage.

[0017] In one embodiment of the present invention, the first reactor, the second reactor, the third reactor and the fourth reactor are all provided with dry activated sludge, and the dry activated sludge arranged in the first reactor, the second reactor, the fourth reactor and the third reactor are brought into contact with the filler through the aerator; wherein the density of the dry activated sludge is 1-1.5 kg / m 3 .

[0018] Compared with the existing technology, the technical effects achieved by adopting this technical solution are: dried activated sludge has higher stability than activated sludge, the microorganisms in dried activated sludge are in a relatively stable state, and can better resist the interference of the external environment; on the other hand, setting dried activated sludge can be used as an inoculum for biofilm to accelerate the formation and growth of biofilm.

[0019] In one embodiment of the present invention, it also includes: a fan; the fan is connected to the first reactor, the second reactor, the third reactor and the fourth reactor through a pipeline, and is used to input gas into the first reactor, the second reactor, the third reactor and the fourth reactor to promote gas exchange.

[0020] In one embodiment of the present invention, a clear water tank is further included, which is arranged on a side of the fourth reactor away from the third reactor; wherein the clear water tank is connected to the fourth reactor for refluxing substandard water.

[0021] Compared with the existing technology, the technical effect achieved by adopting this technical solution is: when the effluent from the fourth reactor does not meet the standards, the substandard water is returned to the fourth reactor through the clear water tank for further treatment.

[0022] In one embodiment of the present invention, the invention further comprises: a nitrification water production tank; the nitrification water production tank is arranged between the third reactor and the fourth reactor.

[0023] After adopting the technical solution of the utility model, the following technical effects can be achieved:

[0024] (1) Using multiple biofilm reactors to work together, a fourth reactor is added at the rear end of the third reactor to reduce the nitrate nitrogen in the third treated water produced in the third reactor into nitrogen gas, thereby effectively reducing the total nitrogen concentration in the effluent and solving the problem of excessive total nitrogen content in the treated water;

[0025] (2) By adopting the biofilm process, the corresponding bacterial species can be cultivated simultaneously in each biofilm reactor, which greatly reduces the startup time of the wastewater treatment system. In addition, the cultivated bacterial species are stable and not easily disturbed by external factors.

[0026] (3) The wastewater treatment system can be separated into the first loop and the second loop by the control valve to cope with the connectivity of the various reactors at different stages of the wastewater treatment system; to prevent the immature biofilm in the reactor with slower biofilm cultivation from falling off the packing rope. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts.

[0028] Figure 1 A structural schematic diagram of an anaerobic ammonium oxidation reaction system provided in an embodiment of the present utility model;

[0029] Figure 2 This is an isometric schematic diagram of an anaerobic ammonium oxidation reaction system provided by an embodiment of the present invention;

[0030] Figure 3 A top view of a first reactor is provided for an embodiment of the present utility model;

[0031] Figure 4 for Figure 3 Cross-sectional view along AA direction.

[0032] Description of reference numerals:

[0033] 1. First reactor; 2. Second reactor; 3. Third reactor; 4. Fourth reactor; 5. Clear water tank; 6. Biofilm filler; 7. Sulfur autotrophic filler; 8. Microporous aerator; 9. First water pump; 10. Filter; 11. Mud discharge pipe; 12. Second water pump; 13. Third water pump; 14. Fourth water pump; 15. Roots blower; 16. Perforated aerator; 17. Nitrification water production tank; 18. Pipeline; 19. Aeration head. DETAILED DESCRIPTION

[0034] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0035] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connection, connection, or integral connection; they can refer to mechanical connection or electrical connection; they can refer to direct connection or indirect connection through an intermediate medium; and they can refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0037] See also Figure 1 , Figure 1 A structural schematic diagram of an anaerobic ammonium oxidation reaction system provided in an embodiment of the present invention. Specifically, the present invention provides an anaerobic ammonium oxidation reaction system, the reaction system including a wastewater treatment system, the wastewater treatment system including: a first reactor 1, a second reactor 2, a third reactor 3 and a fourth reactor 4; wherein the first reactor 1 is used to remove nitrate nitrogen in the wastewater and produce a first treated water; the second reactor 2, the second reactor 2 is arranged on one side of the first reactor 1, and is used to remove ammonia nitrogen and nitrite nitrogen in the first treated water and produce a second treated water; the third reactor 3, the third reactor 3 is arranged on a side of the second reactor 2 away from the first reactor 1, and is used to adjust the nitrogen composition and concentration of the second treated water and produce a third treated water; the fourth reactor 4, the fourth reactor 4 is arranged on a side of the third reactor 3 away from the second reactor 2, and is used to reduce nitrate nitrogen in the treated water to nitrogen gas to reduce the concentration of total nitrogen in the effluent.

[0038] Preferably, the first reactor 1 includes a denitrification biofilm reactor, the second reactor 2 includes an anaerobic ammonium oxidation biofilm reactor, the third reactor 3 includes a short-cut nitrification biofilm reactor, and the fourth reactor 4 includes a sulfur autotrophic denitrification reactor.

[0039] Preferably, the wastewater treatment system includes an operating state and a debugging state; wherein, the first reactor 1, the second reactor 2, the third reactor 3 and the fourth reactor 4 are connected in sequence through the pipeline 18 to form a first loop, and at this time the wastewater treatment system is in an operating state; the first reactor 1, the third reactor 3 and the fourth reactor 4 form a second loop through the pipeline 18, and the second reactor 2 operates alone, and at this time the wastewater treatment system is in a debugging state.

[0040] Further, combined Figure 3 and Figure 4 The first reactor 1 , the second reactor 2 , the third reactor 3 and the fourth reactor 4 are all equipped with biofilm fillers 6 to cultivate a single bacterial species corresponding to each reactor.

[0041] Furthermore, the biofilm filler 5 is a braided filler rope or a sheet filler rope.

[0042] Preferably, the fourth reactor 4 is filled with sulfur autotrophic filler 7 for cultivating sulfur autotrophic bacteria.

[0043] Preferably, an aerator is provided at the bottom of the first reactor 1 , the second reactor 2 , the third reactor 3 and the fourth reactor 4 .

[0044] Preferably, the aerator includes a microporous aerator 8 and a perforated aerator 16 .

[0045] Preferably, a microporous aerator 8 is provided at the bottom of the third reactor 3 .

[0046] Preferably, a perforated aerator 16 is provided at the bottom of the first reactor 1 , the second reactor 2 and the fourth reactor 4 .

[0047] Preferably, a plurality of aeration heads 19 are provided along the axial direction of the perforated aerator 16 .

[0048] See also Figure 2 Preferably, the wastewater treatment system further includes: a plurality of control valves; the control valve is arranged between any two reactors, and is used to control the communication between the reactors; wherein, by opening the control valve, the wastewater treatment system forms a first loop; by closing the control valve, the wastewater treatment system is switched from the first loop to the second loop; similarly, opening the corresponding control valve can also switch the wastewater treatment system from the second loop to the first loop.

[0049] Optionally, the wastewater treatment system also includes a fan, which is connected to the first reactor 1, the second reactor 2, the third reactor 3 and the fourth reactor 4 respectively, and is used to input gas into the first reactor 1, the second reactor 2, the third reactor 3 and the fourth reactor 4 to promote gas exchange in each reactor.

[0050] Preferably, the blower includes a Roots blower 15 .

[0051] Preferably, the wastewater treatment system further includes: a nitrification water production tank 17 ; the nitrification water production tank 17 is disposed between the third reactor 3 and the fourth reactor 4 .

[0052] Preferably, the wastewater treatment system includes a first water pump 9, a second water pump 12, a third water pump 13 and a fourth water pump 14; wherein, the first water pump 9 includes a raw water pump, the second water pump 12 includes an internal circulation pump of the ammonia oxidation reactor, the third water pump 13 includes a nitrate nitrogen reflux pump and the fourth water pump 14 includes a sulfur autotrophic reflux pump.

[0053] Preferably, the first water pump 9 is provided at the front end of the wastewater treatment system for inputting wastewater into the first reactor 1 .

[0054] Preferably, the second water pump 12 is connected to the second reactor 2 to promote mixing of substances in the second reactor 2 .

[0055] Preferably, the third water pump 13 is located between the nitrification water production tank 17 and the third reactor 3 , and is connected to the third reactor 3 .

[0056] Preferably, the fourth water pump 14 is provided between the third water pump 13 and the fourth reactor 4 and connects the nitrification water production tank 17 and the fourth reactor 4 to improve the utilization rate of sulfur.

[0057] Preferably, the wastewater treatment system further comprises a filter 10 , which is provided between the raw water pump and the first reactor 1 and is used for performing a first filtration treatment on the input wastewater.

[0058] Preferably, the first reactor 1, the second reactor 2, the third reactor 3 and the fourth reactor 4 are all provided with dried activated sludge, and the dried activated sludge arranged in the first reactor 1, the second reactor 2, the fourth reactor 4 and the third reactor 3 are brought into contact with the filler through the aerator; wherein the density of the dried activated sludge is 1-1.5 kg / m 3 .

[0059] Preferably, the wastewater treatment system further comprises: a clear water tank 5, which is arranged on a side of the fourth reactor 4 away from the third reactor 3; wherein the clear water tank 5 is connected to the fourth reactor 4 for refluxing substandard water.

[0060] Preferably, the wastewater treatment system further includes: a mud discharge pipe 11 , which is arranged at the bottom of the first water pump 9 , the second water pump 12 , the third water pump 13 and the fourth water pump 14 .

[0061] In one embodiment, when the wastewater treatment system is in operation, it includes:

[0062] Debugging phase:

[0063] The commissioning phase includes the following steps:

[0064] Before film formation:

[0065] Install sheet-type or braided biofilm filler 6 into the first reactor 1, the second reactor 2, the third reactor 3, and the fourth reactor 4; wherein the biofilm filler 6 comprises sheet-type filler rope or braided filler rope, and add clean water into the first reactor 1, the second reactor 2, the third reactor 3, and the fourth reactor 4 respectively, overflowing the filler rope;

[0066] Add 1-1.5 kg / m2 of water to the first reactor 1, the second reactor 2, the third reactor 3 and the fourth reactor 4. 3 Add dried activated sludge, and start the perforated aerators 16 of the first reactor, the second reactor, and the fourth reactor, and start the microporous aerator 8 of the third reactor 3, so that the sludge in the first reactor 1, the second reactor 2, the third reactor 3, and the fourth reactor 4 is evenly mixed and fully in contact with the filler;

[0067] A small amount of water is added to the first reactor 1 so that the ammonia nitrogen concentration in the first reactor 1 is less than 200 mg / L, and the perforated aerator 16 is kept open to allow denitrifying bacteria to gradually multiply in a suitable environment and provide a nitrogen source to the denitrifying bacteria so that they use the organic matter in the influent as a carbon source to carry out nitrification reaction; the perforated aerator 16 of the second reactor 2 is controlled to be open all the time to maintain an anoxic state so that the anaerobic ammonia-oxidizing bacteria begin to grow slowly, the microporous aerator 8 of the third reactor 3 is continuously opened, the dissolved oxygen concentration of the second reactor 2 and the third reactor 3 is controlled to be 0.5-1.0 mg / L, and the third water pump 13 is turned on to control the ammonia nitrogen concentration of the effluent of the third reactor 3 to be less than 15 mg / L to prevent the ammonia nitrogen concentration from being too high and inhibiting the growth of short-range nitrifying bacteria, and the above process is kept running for one week;

[0068] Sodium thiosulfate and sodium nitrate are added to the fourth reactor 4 to enable the sulfur autotrophic denitrifying bacteria to use the sulfur source and nitrate nitrogen to carry out denitrification reaction. The sulfur concentration in the fourth reactor 4 is controlled to be maintained at 500 mg / L, and the nitrate nitrogen concentration is maintained at 250 mg / L. The perforated aerator 16 of the fourth reactor 4 is turned on for five minutes to fully mix the activated sludge with the reagent to promote the attachment and growth of the bacteria on the filler rope, and the fourth water pump 14 is turned on. A temporary pump is placed in the clear water tank 5. When the total nitrogen in the effluent of the fourth reactor 4 does not meet the standard, the temporary pump is turned on to return the effluent to the fourth reactor 4 for further treatment. After one week, biofilm formation is completed.

[0069] Furthermore, since the bacteria cultured in the second reactor 2 are long-term, the second reactor 2 is operated alone to prevent the uncultured mature biofilm in the second reactor 2 from being blown off;

[0070] After film formation:

[0071] The sewage is fed into the first reactor 1 after passing through the filter 10 by the first water pump 9, and the third water pump 13 is controlled to be intermittently turned on, and the microporous aerator 8 of the third reactor 3 is controlled to be intermittently turned on to promote the ammonia reaction and convert organic nitrogen into ammonia nitrogen, thereby increasing the ammonia nitrogen concentration in the third reactor 3 and maintaining it at 200 mg / L. The pH value in the third reactor 3 is maintained at 8.3 by adding alkali, providing a suitable growth environment for short-range nitrifying bacteria;

[0072] The water inflow into the first reactor 1 is stopped, and the operation of the third water pump 13 is stopped, so that the first reactor 1 can concentrate on treating the sewage inside it and avoid further introduction of more sewage;

[0073] The microporous aerator 8 of the third reactor 3 is always turned on to control the dissolved oxygen concentration in the third reactor 3 to be 1.0-1.5 mg / L and the ammonia nitrogen concentration to be reduced to less than 15 mg / L, thereby providing suitable dissolved oxygen conditions for the short-range nitrifying bacteria, which is conducive to the short-range nitrifying bacteria oxidizing the ammonia nitrogen into nitrite. The wastewater in the nitrification water production tank 17 is then returned to the third reactor 3 until the ammonia nitrogen concentration in the nitrification water production tank 17 is reduced to less than 15 mg / L.

[0074] Repeat the above steps to continuously strengthen the short-range nitrification reaction, so that the accumulation of nitrite gradually increases, making the concentration of nitrite and nitrate in the wastewater greater than 3 mg / L. At this time, the short-range nitrifying bacteria in the third reactor 3 are cultivated and the short-range nitrification reaction proceeds stably.

[0075] After the short-cut nitrifying bacteria culture is completed, the first reactor 1 starts to continuously feed water to maintain the stability of the short-cut nitrifying reaction. The third water pump 13 is always turned on, and the reflux ratio is controlled at a ratio of raw water total nitrogen / 200 to adjust the amount and water quality of sewage entering the third reactor 3 to ensure that the short-cut nitrifying reaction can proceed under suitable conditions. The concentration of lysozyme in the third reactor 3 is controlled at 0.5-1.0 mg / L to provide a good growth environment for the short-cut nitrifying bacteria.

[0076] After the membrane is formed in the fourth reactor 4, the nitrate nitrogen wastewater in the nitrification water production tank 17 is pumped into the fourth water pump 14 at a flow rate calculated according to the load; when the water produced by the fourth reactor 4 does not meet the discharge requirements, the water in the clear water tank 5 is returned to the fourth reactor 4 through the fourth pump for further treatment to ensure that the effluent water quality meets the standards;

[0077] After the second reactor 2 forms a biofilm, sodium nitrite and ammonium sulfate are added to the second reactor 2 to provide the nitrite and ammonia nitrogen required for the reaction, so that the ammonia nitrogen concentration in the second reactor 2 is maintained at 100 mg / L, and the nitrite content in the second reactor 2 is maintained at 200 mg / L; and the second water pump 12 is continuously turned on to fully mix the sludge and the reagent to improve the reaction efficiency, prevent sludge precipitation, and maintain a uniform sludge concentration in the second reactor 2; since the anaerobic ammonia oxidation reaction consumes nitrite and ammonia nitrogen, nitrite and ammonium sulfate need to be regularly replenished to maintain the nitrite and ammonia nitrogen concentrations in the wastewater treatment system.

[0078] During the operation phase:

[0079] When the short-cut nitrification reaction is achieved, the wastewater treatment system performs treatment operations according to the first loop until the design load is reached.

[0080] Although the present invention is disclosed as above, it is not limited thereto. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope defined by the claims.

Claims

1. An anaerobic ammonium oxidation reaction system, characterized in that: The reaction system includes a wastewater treatment system; the wastewater treatment system includes: A first reactor (1) is used to remove nitrate nitrogen from wastewater and produce first treated water; a second reactor (2), the second reactor (2) being arranged on one side of the first reactor (1), and being used for removing ammonia nitrogen and nitrite nitrogen from the first treated water and producing second treated water; a third reactor (3), the third reactor (3) being arranged on a side of the second reactor (2) away from the first reactor (1), and being used to adjust the nitrogen composition and concentration of the second treated water and produce third treated water; a fourth reactor (4), the fourth reactor (4) being arranged on a side of the third reactor (3) away from the second reactor (2), and being used for treating nitrate nitrogen in the third treated water and reducing it to nitrogen gas, so as to reduce the concentration of total nitrogen in the effluent; The first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) are connected in sequence through a pipeline (18); the first reactor (1) includes a denitrification biofilm reactor, the second reactor (2) includes an anaerobic ammonia oxidation biofilm reactor, the third reactor (3) includes a short-range nitrification biofilm reactor, and the fourth reactor (4) includes a sulfur autotrophic denitrification reactor.

2. The reaction system according to claim 1, characterized in that The first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) are all equipped with biofilm fillers (6); The biofilm filler (6) is braided or sheet-like.

3. The reaction system according to claim 1 or 2, characterized in that Aerators are provided at the bottom of the first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4).

4. The reaction system according to claim 1, characterized in that The fourth reactor (4) is filled with sulfur autotrophic filler (7) for cultivating sulfur autotrophic bacteria.

5. The reaction system according to claim 3, characterized in that Also includes: Multiple control valves; The control valve is provided between any two reactors and is used to control the communication between the reactors; wherein, by opening the control valve, the wastewater treatment system forms a first loop; By closing the control valve, the wastewater treatment system is switched from the first loop to the second loop.

6. The reaction system according to claim 5, characterized in that The first loop is formed by the first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) being connected in sequence through the pipeline (18), and the wastewater treatment system is in the operation stage at this time; The second loop is formed by the first reactor (1), the third reactor (3) and the fourth reactor (4) being connected in sequence through the pipeline (18), so that the second reactor (2) operates alone. At this time, the wastewater treatment system is in the commissioning stage.

7. The reaction system according to claim 6, characterized in that The first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) are all provided with dried activated sludge, and the dried activated sludge arranged in the first reactor (1), the second reactor (2), the fourth reactor (4) and the third reactor (3) are brought into contact with fillers through the aerator; The density of the dry activated sludge is 1-1.5 kg / m 3 .

8. The reaction system according to claim 1, characterized in that Also includes: Fan; The blower is connected to the first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) through the pipeline (18), and is used to input gas into the first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) to promote gas exchange.

9. The reaction system according to claim 1, characterized in that include: A clear water tank (5), the clear water tank (5) is arranged on a side of the fourth reactor (4) away from the third reactor (3); wherein the clear water tank (5) is connected to the fourth reactor (4) and is used to recirculate substandard water.

10. The reaction system according to claim 9, characterized in that Also includes: Nitrification water production tank (17); the nitrification water production tank (17) is arranged between the third reactor (3) and the fourth reactor (4).

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