Mainstream anaerobic ammonia oxidation enhanced denitrification device and method based on fluidized bed biofilm

Abstract

A mainstream anaerobic ammonia oxidation enhanced denitrification device and method based on a fluidized bed biofilm. By arranging reaction tanks, switching of two operation modes can be achieved, and recovery of instability in starting and running periods is completed. A denitrification pathway comprises: implementing denitrification and partial denitrification-anaerobic ammonia oxidation synergy in an anoxic zone; and implementing nitrification, synchronous nitrification and denitrification, and partial nitrification-anaerobic ammonia oxidation synergy in an aerobic zone. Implementation of anaerobic ammonia oxidation for denitrification in the anoxic zone or the aerobic zone requires first enhancement of an aerobic biofilm, enhancement of the thickness of the biofilm under the action of high DO, and formation of an internal anoxic / anaerobic layer, thereby providing conditions for enrichment of anaerobic ammonia oxidizing bacteria.

Description

Mainstream anaerobic ammonium oxidation enhanced denitrification equipment and method based on fluidized bed biofilm Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to mainstream anaerobic ammonia oxidation enhanced denitrification equipment and method based on fluidized bed biofilm. Background Art

[0002] The current sewage treatment industry is affected by problems such as high energy consumption of nitrification aeration and excessive addition of carbon sources for denitrification, and carbon emissions are constantly increasing. It has ranked among the top ten high-carbon emission industries in the country. In order to achieve carbon peak and carbon neutrality as soon as possible, it is necessary to improve the existing sewage treatment process and realize green and low-carbon sewage treatment.

[0003] The anaerobic ammonium oxidation (ANAMMOX) process, based on anaerobic ammonium-oxidizing bacteria, utilizes ammonia nitrogen and nitrous oxide as substrates to achieve autotrophic nitrogen removal. This eliminates the reliance of wastewater denitrification on raw water carbon sources and is key to achieving energy support for wastewater treatment. In practical applications, the key to achieving ANAMMOX autotrophic nitrogen removal lies in obtaining a stable source of nitrite, so it is often used in conjunction with short-cut denitrification (PDN) and short-cut nitrification (PN), and is primarily applied to the treatment of high-temperature, high-ammonia nitrogen wastewater. Mainstream municipal wastewater has the characteristics of low substrate, large fluctuations, and low temperature, making it difficult to achieve a stable short-cut nitrification effect. In addition, the high C / N ratio of municipal wastewater and the short hydraulic retention time of traditional activated sludge processes also make it impossible to achieve a stable short-cut denitrification effect. Therefore, achieving stable ANAMMOX treatment of mainstream municipal wastewater remains an industry challenge.

[0004] Although researchers have explored the above-mentioned industry challenges, many technical problems still exist:

[0005] CN107253762B, CN 113200600 B, CN112811719B, CN112456643A, etc. all disclose methods for rapid start-up of anaerobic ammonium oxidation. However, in terms of specific measures, either seed inoculation is used without achieving autonomous cultivation of the seed; or side stream sludge digestate is intermittently used to enhance short-range nitrification, which cannot achieve rapid start-up and stable operation of mainstream anaerobic ammonium oxidation in the true sense. CN107512774B, CN110697892A, CN110330180B, CN114212885A, etc. all disclose anaerobic ammonia oxidation autotrophic denitrification methods for mainstream municipal sewage, but in terms of specific measures, only one of PDN or PN can be used in combination with anaerobic ammonia oxidation, and the overall autotrophic denitrification contribution rate is low; in addition, for the start-up of anaerobic ammonia oxidation, it also often needs to be completed by inoculation, which cannot overcome the bottleneck of difficult seed source acquisition; CN114477420B discloses a method and device for achieving deep denitrification of sewage by dual-coupling anaerobic ammonia oxidation of continuous flow AOA short-range nitrification and endogenous short-range denitrification. It pumps municipal domestic sewage into a continuous flow reactor and operates in anaerobic, aerobic, and anoxic modes. The anaerobic zone stores internal carbon sources and releases phosphorus. The aerobic zone undergoes short-term nitrification and anaerobic ammonium oxidation and absorbs phosphorus. The anoxic zone undergoes endogenous short-term nitrification and anaerobic ammonium oxidation. Suspended and fixed biological carriers are added to the aerobic and anoxic zones respectively to retain and enrich anaerobic ammonium-oxidizing bacteria. Ultimately, dual coupling of anaerobic ammonium oxidation is achieved in the aerobic and anoxic zones, improving the efficiency of nitrogen and phosphorus removal. However, there are still the following problems: First, it has high requirements for influent water quality and is only suitable for sewage with an influent COD of less than 250mg / L. Second, the retention time is long. This invention can achieve a hydraulic retention time of 9-15h, which is relatively long overall.

[0006] It can be seen that the existing technology for achieving anaerobic ammonia oxidation denitrification of mainstream municipal sewage mainly has the following problems:

[0007] First, there are the issues of seed source acquisition, which are often achieved through inoculation of mature seed sources or intermittent cultivation in the sidestream and mainstream. Second, the process, which is often based on activated sludge, is difficult to achieve stable retention of bacterial strains during actual operation. Finally, the high water quality requirements for treatment make it difficult to adapt to different water qualities and low-temperature water, which limits its application prospects. Therefore, the existing technology needs further improvement. Summary of the Invention

[0008] The present invention proposes mainstream anaerobic ammonia oxidation enhanced denitrification equipment and method based on fluidized bed biofilm. Based on pure membrane MBBR operation, the method of the present invention is used to treat municipal sewage. The single pool residence time can be as low as 1 hour, and the total residence time can be as low as 6 hours, thereby improving the denitrification efficiency.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on a fluidized bed biofilm, comprising the following steps:

[0011] S0. Set up the required equipment

[0012] The equipment includes four reaction tanks arranged in a "field" shape, which are the first reaction tank, the second reaction tank, the third reaction tank and the fourth reaction tank in clockwise order. A first aerobic tank is arranged between the second reaction tank and the fourth reaction tank in the horizontal direction, and a second aerobic tank is arranged between the first reaction tank and the third reaction tank. First water passing corridors, second water passing corridors and third water passing corridors are respectively arranged on the outer side walls of the first and second reaction tanks, the outer side walls of the second and third reaction tanks, and the outer side walls of the third and fourth reaction tanks. The first water passing corridor and the second water passing corridor, and the second water passing corridor and the third water passing corridor can communicate with each other;

[0013] The hydraulic retention time in the first to fourth reaction tanks and the first and second aerobic tanks is 1.0 - 1.5 h, the suspended sludge concentration in the equipment is ≤ 500 mg / L, and suspended carriers are added to all;

[0014] The first reaction tank to the fourth reaction tank can be adjusted to be an aerobic tank / anoxic tank;

[0015] Through relevant adjustments, the equipment can achieve two operation modes, which are as follows:

[0016] Operation mode 1:

[0017] Inflow direction: First reaction tank → Second reaction tank → Second water passing corridor → Third water passing corridor → Third reaction tank → Fourth reaction tank → First aerobic tank → Second aerobic tank;

[0018] Nitrified liquid flow direction: Second aerobic tank → First reaction tank;

[0019] Operation mode 2:

[0020] Inflow direction: Third reaction tank → Fourth reaction tank → Second water passing corridor → First water passing corridor → First reaction tank → Second reaction tank → First aerobic tank → Second aerobic tank;

[0021] Nitrified liquid flow direction: Second aerobic tank → Third reaction tank;

[0022] When using operation mode 1, adjust the first reaction tank and the second reaction tank to be anoxic tanks, and the third reaction tank and the fourth reaction tank to be aerobic tanks. The operation mode is: Anoxic tank → Anoxic tank → Aerobic tank → Aerobic tank → First aerobic tank → Second aerobic tank, to play the role of nitrification and denitrification for nitrogen removal; The nitrogen removal loads of the first reaction tank and the second reaction tank are respectively greater than 1.0 and 0.8 gN / m 2 / d, or the TN of the effluent from the second reaction tank is less than 5mg / L; the nitrification load of the third reaction tank, the fourth reaction tank, the first aerobic tank and the second aerobic tank is greater than 0.5gN / m 2 / d, or the ammonia nitrogen in the effluent of the second aerobic pool is less than 1mg / L;

[0023] S1, simultaneous nitrification and denitrification culture in the third and fourth reaction tanks

[0024] Increase the DO of the third and fourth reaction tanks to 6-8 mg / L, operate until the biofilm thickness of the third and fourth reaction tanks is greater than 450 μm and 350 μm respectively, the ammonia nitrogen removal contribution rate is greater than 90%, and the denitrification load is greater than 0.1 gN / m 2 / d;

[0025] S2, the third reaction tank and the fourth reaction tank anaerobic ammonia oxidation culture

[0026] Switch to operation mode 2, the corresponding operation mode is anoxic pool → anoxic pool → anoxic pool → anoxic pool → first aerobic pool → second aerobic pool;

[0027] Adjust the C / N ratio of the influent to the third reaction tank to 2.5-3.0, and operate until the ammonia nitrogen removal load of the third and fourth reaction tanks is greater than 0.15 gN / m 2 / d, 0.10gN / m 2 / d, and the relative abundance of anaerobic ammonium oxidizing bacteria was >1.0%;

[0028] S3, simultaneous nitrification and denitrification culture in the first and second reaction tanks

[0029] Adjust the first and second reaction tanks to aerobic tanks, and increase the DO of the first and second reaction tanks to 6-8 mg / L. Operate until the biofilm thickness of the first and second aerobic tanks is greater than 500 μm and 400 μm respectively, and the denitrification load is greater than 0.1 gN / m 2 / d;

[0030] S4, the first and second reaction tanks are inoculated with the third and fourth reaction tanks for anaerobic ammonia oxidation

[0031] Reduce the DO of the first and second reaction tanks to 2-4 mg / L, and operate until the total nitrogen removal load of the first and second reaction tanks is greater than 0.2 gN / m 2 / d, and the relative abundance of anaerobic ammonium oxidizing bacteria was greater than 0.5%;

[0032] S5, anaerobic ammonium oxidation oxygen-limited enhancement in the first and second reaction tanks;

[0033] S6, denitrification and anaerobic ammonium oxidation recovery in the first and second reaction tanks;

[0034] S7, simultaneous nitrification and denitrification recovery in the third and fourth reaction tanks;

[0035] S8, anaerobic ammonia oxidation recovery in the third and fourth reaction tanks.

[0036] In the above-mentioned mainstream anaerobic ammonium oxidation enhanced denitrification method based on fluidized bed biofilm, the specific adjustment method of step S5 is: gradually increase the DO of the first reaction tank and the second reaction tank by 0.5-1.0 mg / L, and operate until the sum of the denitrification load of the first reaction tank and the second reaction tank reaches the maximum, and the relative abundance of anaerobic ammonium oxidizing bacteria is greater than 1.0%;

[0037] If the denitrification load or the relative abundance of anaerobic ammonia-oxidizing bacteria from the first to the second reaction tank decreases by more than 30%, S6 and S8 will be run. If the ammonia nitrogen removal load or the relative abundance of anaerobic ammonia-oxidizing bacteria from the third to the fourth reaction tank decreases by more than 30%, S7 and S8 will be run.

[0038] The above-mentioned mainstream anaerobic ammonium oxidation enhanced denitrification method based on fluidized bed biofilm, the specific adjustment method of step S6 is: switch to operation mode 1, and adjust the first reaction tank and the second reaction tank to anoxic operation, adjust the C / N ratio of the influent of the first reaction tank to 2.5-3.0, and operate until the ammonia nitrogen removal load of the first reaction tank and the second reaction tank is greater than 0.15 gN / m 2 / d, 0.10gN / m 2 / d, and the average relative abundance of anaerobic ammonia-oxidizing bacteria was >1.0%.

[0039] The above-mentioned mainstream anaerobic ammonium oxidation enhanced denitrification method based on fluidized bed biofilm, the specific adjustment method of step S7 is: increase the DO of the third reaction tank and the fourth reaction tank to 6-8 mg / L, operate until the biofilm thickness of the third reaction tank and the fourth reaction tank is respectively greater than 500μm and 400μm, and the denitrification load is greater than 0.1gN / m 2 / d;

[0040] The above-mentioned mainstream anaerobic ammonium oxidation enhanced denitrification method based on fluidized bed biofilm, the specific adjustment method of step S8 is: switch to operation mode 2, the third and fourth reaction tanks are operated in anoxic mode, adjust the C / N ratio of the influent of the third reaction tank to 2.5-3.0, and operate until the ammonia nitrogen removal load of the third and fourth reaction tanks is greater than 0.15 gN / m 2 / d, 0.10gN / m 2 / d, and the average relative abundance of anaerobic ammonium oxidizing bacteria is >1.0%; then return to S5 operation.

[0041] The above-mentioned mainstream anaerobic ammonia oxidation enhanced denitrification method based on fluidized bed biofilm is equipped with a stirring device and an aeration pipeline in the first reaction tank, the second reaction tank, the third reaction tank and the fourth reaction tank. By turning on the stirring device, each reaction tank can be adjusted to an anoxic tank, and by turning on the aeration device, each reaction tank can be adjusted to an aerobic tank.

[0042] In the above-mentioned mainstream anaerobic ammonia oxidation enhanced denitrification method based on fluidized bed biofilm, the first reaction tank is connected to the first total water inlet pipeline, the third reaction tank is connected to the second total water inlet pipeline, and the second aerobic tank is connected to the total water outlet pipeline; the first water gate and the second water gate are respectively provided at both ends of the second water passage.

[0043] In the above-mentioned mainstream anaerobic ammonia oxidation enhanced denitrification method based on fluidized bed biofilm, an interception screen is provided in front of the water outlet of each reaction tank, and adjacent reaction tanks are kept connected through water outlets; a first nitrification liquid reflux pump and a second nitrification liquid reflux pump are provided behind the interception screen in the second aerobic tank.

[0044] The above mainstream anaerobic ammonium oxidation enhanced denitrification method based on fluidized bed biofilm, when building the required equipment, the shape of the suspended carrier is flat cylindrical porous honeycomb, the material is high-density polyethylene material, the effective specific surface area is ≥620m 2 / m 3 The suspended carrier filling rate is greater than 45%; the suspended carrier density in the first reaction tank and the second reaction tank is 0.97-1.00 g / cm 3 The average gap spacing of the suspended carrier is ≥3mm, and the density of the suspended carrier in the third reaction tank and the fourth reaction tank is 1.00~1.03g / cm 3 The average gap spacing of the suspended carrier is ≥4mm, and the density of the suspended carrier in the first aerobic tank and the second aerobic tank is 0.94-0.97g / cm 3 , the average gap spacing of the suspended carrier is ≥5mm; the temperature of the sewage treated by the equipment is ≥10℃, and the C / N ratio is ≥3; the ammonia nitrogen and total nitrogen in the effluent of the equipment in steps S0 to S8 are both required to be less than 0.5mg / L and 5mg / L; the method for adjusting the C / N ratio in step S2 is to adjust the reflux ratio and to introduce raw water into the third reaction tank at 0-10% of the equipment inlet flow rate; the method for adjusting the C / N ratio in steps S6 and S8 is to adjust the reflux ratio.

[0045] Another object of the present invention is to provide a mainstream anaerobic ammonia oxidation enhanced denitrification equipment based on a fluidized bed biofilm, the equipment comprising four reaction tanks arranged in a "field" shape, namely, a first reaction tank, a second reaction tank, a third reaction tank, and a fourth reaction tank in a clockwise direction, a first aerobic tank being arranged between the second reaction tank and the fourth reaction tank in the transverse direction, a second aerobic tank being arranged between the first reaction tank and the third reaction tank, a first water passage corridor, a second water passage corridor, and a third water passage corridor being arranged on the outer pool walls of the first and second reaction tanks, the outer pool walls of the second and third reaction tanks, and the outer pool walls of the third and fourth reaction tanks, respectively, the first water passage corridor and the second water passage corridor, the second water passage corridor and the third water passage corridor being interconnected;

[0046] The hydraulic retention time in the first to fourth reaction tanks and the first and second aerobic tanks is 1.0 to 1.5 hours, the suspended sludge concentration in the equipment is ≤ 500 mg / L, and suspended carriers are added;

[0047] The first to fourth reaction tanks can be adjusted to aerobic tanks or anoxic tanks. Aeration devices and stirring devices are provided in the first to fourth reaction tanks. By turning on the stirring device, the corresponding reaction tank is adjusted to anoxic tank, and by turning on the aeration device, the corresponding reaction tank is adjusted to anoxic tank.

[0048] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0049] 1) Energy saving and consumption reduction. After the present invention is successfully started, the third and fourth reaction tanks serve as anoxic zones, and the first and second reaction tanks serve as oxygen-limited zones. The anaerobic ammonium oxidation load can reach 0.5 gN / m 3 / d and 0.4gN / m 2 / d, the overall anaerobic ammonium oxidation load of the equipment is 0.9gN / m 2 / d or more, the denitrification contribution rate can reach more than 50%, which can completely get rid of the dependence on external carbon sources for denitrification of low carbon-nitrogen ratio sewage; at the same time, it can reduce aeration energy consumption by more than 20%.

[0050] 2) Wide range of applications and strong low-temperature resistance. This invention can be applied to the treatment of high- and low-matrix municipal sewage and high-ammonia nitrogen industrial water, with the minimum treatment water temperature being as low as 10°C.

[0051] 3) High effluent standards. From startup to stable operation, the present invention can achieve effluent ammonia nitrogen and total nitrogen levels below 0.5 mg / L and 5 mg / L, respectively, meeting the most stringent total nitrogen emission standards currently in place in China.

[0052] 4) High relative abundance of anaerobic ammonium oxidizing bacteria. The present invention can ultimately achieve a relative abundance of anaerobic ammonium oxidizing bacteria in the biofilm of the third and fourth reaction tanks as anoxic zones and the first and second reaction tanks as oxygen-limited zones, both exceeding 1%, which is more than 10 times higher than that reported in China.

[0053] 5) Land-saving. This invention is based on pure membrane MBBR operation. The sludge concentration in each reaction tank is ≤500mg / L. When treating conventional municipal sewage, the residence time per tank can be as low as 1 hour, and the total residence time can be as low as 6 hours. Compared with traditional processes with the same water quality and water quantity, it saves more than 70% of land.

[0054] The equipment of the present invention as a whole cooperates with two operating modes, and switches between the two modes by controlling process conditions and parameters, thereby improving denitrification efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The present invention will be further described below with reference to the accompanying drawings:

[0056] FIG1 is a schematic structural diagram of the equipment of the present invention;

[0057] In the figure: C1, the first reaction tank, C2, the second reaction tank, C3, the third reaction tank, C4, the fourth reaction tank, O1, the first aerobic tank, O2, the second aerobic tank, I1, the first total water inlet pipeline, I2, the second total water inlet pipeline, I3, the total water outlet pipeline, G1, the first water outlet, G2, the second water outlet, G3, the third water outlet, G4, the fourth water outlet, G5, the fifth water outlet, G6, the sixth water outlet, G7, the seventh water outlet, G8, the eighth water outlet, G9, the ninth water outlet, G10, the tenth water outlet, G11, the eleventh water outlet, L1, the first water passage, L2, the second water passage, L3, the third water passage, F1, the first water gate, F2, the second water gate, P1, the first nitrification liquid reflux pump, P2, the second nitrification liquid reflux pump.

[0058] Figure 2 shows the changes in ammonia nitrogen removal load and relative abundance of anaerobic ammonia-oxidizing bacteria in the third and fourth reaction tanks in Comparative Example 3 under different influent C / N. DETAILED DESCRIPTION

[0059] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0060] In the description of this application, words such as "first" and "second" are used only to distinguish different objects and do not limit the quantity or execution order. In addition, words such as "first" and "second" do not necessarily mean different. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0061] The structures and working principles of the stirring device and aeration device described in the present invention can be realized by those skilled in the art by referring to the existing technology.

[0062] The following is an explanation of the technical terms that appear in this article:

[0063] Denitrification load: the amount of total nitrogen removed by biofilm per unit area per unit time, gN / m 2 / d;

[0064] Nitrification load: the amount of ammonia nitrogen removed by nitrification reaction per unit area of ​​biofilm under aerobic conditions per unit time, gN / m 2 / d;

[0065] DO: dissolved oxygen, molecular oxygen dissolved in water, mg / L;

[0066] Biofilm thickness: the average thickness from the outermost layer of the biofilm to the contact carrier, μm;

[0067] Ammonia nitrogen removal contribution rate: the percentage of ammonia nitrogen removed by a certain reaction tank to the amount of ammonia nitrogen removed by the entire equipment, %;

[0068] Ammonia nitrogen removal load: the amount of ammonia nitrogen removed by the biofilm per unit area per unit time, gN / m 2 / d;

[0069] Relative abundance of anaerobic ammonium oxidizing bacteria: the percentage of anaerobic ammonium oxidizing bacteria in the total number of all bacteria, %;

[0070] C / N: For the total influent, it refers to the ratio of COD to TN concentration in the sewage; for other reaction tanks, it refers to the ratio of dissolved COD to NO in the sewage. x - -Ratio of N concentration.

[0071] The technical solution of the present application is further described in detail below with reference to the accompanying drawings.

[0072] The main technical concept of the present invention is:

[0073] By arranging the equipment in the reaction tank, the conversion between the two operating modes can be achieved, and the recovery from instability during startup and operation can be completed. Denitrification path: The present invention can ultimately achieve denitrification and short-term denitrification-anaerobic ammonium oxidation synergy in the anoxic zone; nitrification, synchronous nitrification and denitrification, and short-term denitrification-anaerobic ammonium oxidation synergy in the aerobic zone; ANAEROBIC AMMONIA OXIDATION Implementation Method: Regardless of whether it is an anoxic zone or an anaerobic zone, ANAEROBIC AMMONIA OXIDATION denitrification must first be achieved through aerobic biofilm strengthening, strengthening the biofilm thickness under the action of high DO, forming an internal anoxic and anoxic layer, and providing conditions for the survival of ANAEROBIC AMMONIA OXIDATION bacteria; and for ANAEROBIC AMMONIA OXIDATION in the aerobic zone, inoculation conditions are also required to achieve ANAEROBIC AMMONIA OXIDATION denitrification effect.

[0074] For the present invention, a mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on a fluidized bed biofilm requires ensuring that the ammonia nitrogen and total nitrogen in the equipment effluent are less than 0.5 mg / L and 5 mg / L respectively, the water temperature of the sewage to be treated should be ≥ 10 °C, and C / N ≥ 3; it specifically includes the following steps:

[0075] S0. Set up the required equipment

[0076] The described equipment includes four reaction tanks arranged in a "field" shape. In the clockwise direction, they are the first reaction tank C1, the second reaction tank C2, the third reaction tank C3, and the fourth reaction tank C4. A first aerobic tank O1 is arranged between the second reaction tank and the fourth reaction tank in the horizontal direction, and a second aerobic tank O2 is arranged between the first reaction tank and the third reaction tank. First water passing corridors L1, second water passing corridors L2, and third water passing corridors L3 are respectively arranged on the outer side walls of the first and second reaction tanks, the second and third reaction tanks, and the third and fourth reaction tanks. The three water passing corridors can communicate with each other;

[0077] The hydraulic retention time in the first to fourth reaction tanks and the first and second aerobic tanks is 1.0 - 1.5 h, the suspended sludge concentration in the equipment is ≤ 500 mg / L, and suspended carriers are added;

[0078] The first reaction tank to the fourth reaction tank can be adjusted to an aerobic tank or an anoxic tank. Specifically, stirring devices and aeration devices are arranged in the first reaction tank to the fourth reaction tank. If it needs to be adjusted to an anoxic tank, the stirring device is turned on and the aeration device is turned off. If it needs to be adjusted to an aerobic tank, the aeration device is turned on and the stirring device is turned off.

[0079] The first reaction tank is connected to a first main inlet pipeline I1, the third reaction tank is connected to a second main inlet pipeline I2, and the second aerobic tank is connected to a main outlet pipeline I3.

[0080] Adjacent reaction tanks are kept in communication through water outlets, such as a first total water inlet is provided on the outer wall of the first reaction tank, a first water outlet G1 is provided between the first reaction tank and the second reaction tank, a second water outlet G2 is provided on the outer edge of the wall shared by the first reaction tank and the second aerobic tank, a third water outlet G3 is provided on the outer edge of the wall shared by the first reaction tank and the first water gallery, a fourth water outlet G4 is provided between the second reaction tank and the second water gallery, a fifth water outlet G5 is provided on the outer edge of the wall shared by the second reaction tank and the first aerobic tank; a third water outlet G6 is provided on the outer wall of the third reaction tank Two main water inlets, a sixth water outlet G6 is provided on the outer edge of the pool wall shared by the third water gallery and the third reaction tank, a seventh water outlet G7 is provided between the third reaction tank and the fourth reaction tank, and an eighth water outlet G8 is provided on the outer edge of the pool wall shared by the third reaction tank and the second aerobic tank; a ninth water outlet G9 is provided on the outer edge of the pool wall shared by the fourth reaction tank and the first aerobic tank, a tenth water outlet G10 is provided between the fourth reaction tank and the second water gallery, an eleventh water outlet G11 is provided between the first aerobic tank and the second aerobic tank, and a main water outlet is provided on the outer pool wall of the second aerobic tank.

[0081] A first reaction tank interception screen is provided on the wall of the second reaction tank where the water inlet is located, at one end of the first reaction tank. A second reaction tank interception screen is provided on the wall of the fourth water outlet, at one end of the second reaction tank. The second reaction tank interception screen should be located in front of the fourth and fifth water outlets. A third reaction tank interception screen is provided on the wall of the seventh water outlet, at one side of the third reaction tank. A fourth reaction tank interception screen is provided on the wall of the tenth water outlet, at one end of the fourth reaction tank. The fourth reaction tank interception screen should be located in front of the ninth water outlet. A first aerobic tank interception screen is provided on the wall of the eleventh water outlet, at one end of the first aerobic tank. A second aerobic tank interception screen is provided on the wall of the total water outlet, at one end of the second aerobic tank. The second aerobic tank interception screen should be located in front of the second and eighth water outlets. The interception screens of the first to fourth reaction tanks and the first to second aerobic tanks are the same length as their corresponding tank walls and are arranged parallel to the tank walls.

[0082] The first to fourth reaction tanks are equipped with stirring devices and aeration pipelines. By switching between the stirring devices and aeration pipelines, the first to fourth reaction tanks can be adjusted to aerobic tanks or anoxic tanks. The stirring power of the stirring device is 7.5~15w / m 3 The aeration pipeline should be a perforated aeration pipeline, the opening direction of the aeration holes of the perforated aeration pipe is downward, and the opening diameter is 4-6mm.

[0083] A first nitrification liquid reflux pump P1 and a second nitrification liquid reflux pump P2 are provided behind the interception screen of the second aerobic tank, so that sewage can flow from the second aerobic tank to the third reaction tank and the first reaction tank respectively; a first water gate F1 and a second water gate F2 are provided at both ends of the second water passage respectively.

[0084] By adjusting the equipment of the present invention, two operating modes can be achieved, which are as follows:

[0085] Operation mode 1:

[0086] Influent flow direction: first reaction tank → second reaction tank → second water gallery → third water gallery → third reaction tank → fourth reaction tank → first aerobic tank → second aerobic tank;

[0087] Flow direction of nitrification liquid: second aerobic tank → first reaction tank;

[0088] Operation mode 2:

[0089] Influent flow direction: third reaction tank → fourth reaction tank → second water gallery → first water gallery → first reaction tank → second reaction tank → first aerobic tank → second aerobic tank;

[0090] Flow direction of nitrification liquid: second aerobic tank → third reaction tank;

[0091] When using the first operation mode, the first and second reaction tanks are adjusted to anoxic tanks, and the third and fourth reaction tanks are adjusted to aerobic tanks. The operation mode is: anoxic tank → anoxic tank → aerobic tank → aerobic tank → first aerobic tank → second aerobic tank, and nitrification and denitrification are carried out. The denitrification load of the first and second reaction tanks is greater than 1.0 and 0.8 gN / m respectively. 2 / d, or the TN of the effluent from the second reaction tank is less than 5mg / L; the nitrification load of the third reaction tank, the fourth reaction tank and the first and second aerobic tanks are all greater than 0.5gN / m 2 / d, or the ammonia nitrogen in the effluent of the second aerobic pool is less than 0.5 mg / L;

[0092] Switching between the two operating modes mentioned above can achieve denitrification and short-term denitrification-anaerobic ammonium oxidation synergy in the anoxic zone; nitrification, simultaneous nitrification and denitrification, and short-term nitrification-anaerobic ammonium oxidation synergy in the aerobic zone, ultimately improving the denitrification effect.

[0093] S1, simultaneous nitrification and denitrification culture in the third and fourth reaction tanks

[0094] Increase the DO of the third and fourth reaction tanks to 6-8 mg / L, operate until the biofilm thickness of the third and fourth reaction tanks is >450μm and 350μm respectively, the ammonia nitrogen removal contribution rate is >90%, and the denitrification load is >0.1 gN / m 2 / d; In this step, the control of DO in the third and fourth reaction tanks is particularly critical. Only when DO is controlled at 6-8 mg / L can the biofilm thickness be greater than 450μm and 350μm respectively, and the denitrification load is greater than 0.1 gN / m 2 / d.

[0095] S2, the third reaction tank and the fourth reaction tank anaerobic ammonia oxidation culture

[0096] Switch to operation mode 2, the corresponding operation mode is anoxic pool → anoxic pool → anoxic pool → anoxic pool → first aerobic pool → second aerobic pool;

[0097] Adjust the C / N ratio of the influent to the third reaction tank to 2.5-3.0, and operate until the ammonia nitrogen removal load of the third and fourth reaction tanks is greater than 0.15 gN / m 2 / d, 0.10gN / m 2 / d, and the average relative abundance of anaerobic ammonium oxidizing bacteria is >1.0%; this step must be based on the biofilm thickness and denitrification load in step S1. Only when the biofilm thickness is >450μm and 350μm respectively, and the denitrification load is >0.1 gN / m 2 / d, the anaerobic ammonia oxidation culture of the third reaction tank and the fourth reaction tank can be realized.

[0098] In step S2, the C / N ratio can be adjusted by adjusting the reflux ratio and introducing raw water into the third reaction tank at 0-10% of the equipment inlet flow rate;

[0099] S3, simultaneous nitrification and denitrification culture in the first and second reaction tanks

[0100] Adjust the first and second reaction tanks to aerobic tanks, and increase the DO of the first and second reaction tanks to 6-8 mg / L. Operate until the biofilm thickness of the first and second aerobic tanks is greater than 500 μm and 400 μm respectively, and the denitrification load is greater than 0.1 gN / m 2 / d;

[0101] S4, the first and second reaction tanks are inoculated with the third and fourth reaction tanks for anaerobic ammonia oxidation

[0102] Reduce the DO of the first and second reaction tanks to 2-4 mg / L, and operate until the total nitrogen removal load of the first and second reaction tanks is greater than 0.2 gN / m 2 / d, and the relative abundance of anaerobic ammonium oxidizing bacteria is greater than 0.5%; after the biofilm is aerobic acclimated, it must be inoculated with anaerobic ammonium oxidation in the anoxic tank, otherwise anaerobic ammonium oxidation denitrification cannot be achieved in the aerobic zone.

[0103] S5, anaerobic ammonia oxidation oxygen-limited enhancement in the first and second reaction tanks

[0104] Gradually increase the DO of the first and second reaction tanks by 0.5-1.0 mg / L until the sum of the denitrification loads of the first and second reaction tanks reaches the maximum and the relative abundance of anaerobic ammonia-oxidizing bacteria is >1.0%;

[0105] If the denitrification load or the relative abundance of anaerobic ammonia-oxidizing bacteria decreases by more than 30% from the first reaction tank to the second reaction tank, steps S6 and S8 are executed; if the ammonia nitrogen removal load or the relative abundance of anaerobic ammonia-oxidizing bacteria decreases by more than 30% from the third reaction tank to the fourth reaction tank, steps S7 and S8 are executed;

[0106] S6, denitrification and anaerobic ammonium oxidation recovery in the first and second reaction tanks

[0107] Then switch to operation mode 1, and adjust the first and second reaction tanks to anoxic operation, adjust the C / N ratio of the influent of the first reaction tank to 2.5-3.0, and operate until the ammonia nitrogen removal load of the first and second reaction tanks is greater than 0.15 gN / m 2 / d, 0.10gN / m 2 / d, and the relative abundance of anaerobic ammonium oxidizing bacteria was >1.0%;

[0108] S7, simultaneous nitrification and denitrification recovery in the third and fourth reaction tanks

[0109] Increase the DO of the third and fourth reaction tanks to 6-8 mg / L, and operate until the biofilm thickness of the third and fourth reaction tanks is greater than 500 μm and 400 μm respectively, and the denitrification load is greater than 0.1 gN / m 2 / d;

[0110] S8, third reaction tank, fourth reaction tank anaerobic ammonia oxidation recovery

[0111] Switch to operation mode 2, anoxic operation of the third and fourth reaction tanks, adjust the C / N ratio of the influent of the third reaction tank to 2.5-3.0, and operate until the ammonia nitrogen removal load of the third and fourth reaction tanks is greater than 0.15 gN / m 2 / d, 0.10gN / m 2 / d, and the relative abundance of anaerobic ammonium oxidizing bacteria is greater than 1.0%; then the process returns to step S5. The method for adjusting the C / N ratio in steps S6 and S8 refers to adjusting the reflux ratio.

[0112] Preferably, in the equipment of the present invention, the suspension carrier is in the shape of an oblate cylindrical porous honeycomb, made of high-density polyethylene, with an effective specific surface area of ​​≥620m 2 / m 3, the filling rate of the suspended carriers is greater than 45%, and the density of the suspended carriers in the first and second reaction tanks is 0.97 - 1.00 g / cm 3 , the average void spacing of the suspended carriers is ≥ 3 mm, and the density of the suspended carriers in the third and fourth reaction tanks is 1.00 - 1.03 g / cm 3 , the average void spacing of the suspended carriers is ≥ 4 mm, and the density of the suspended carriers in the first and second aerobic tanks is 0.94 - 0.97 g / cm 3 , the average void spacing of the suspended carriers is ≥ 5 mm.

[0113] The following is an illustration with specific embodiments. Embodiment

[0114] A municipal sewage treatment module with a treatment capacity of 0.7×10 4 m 3 / d, the designed influent water quality is shown in Table 1, and it operates according to the following steps.

[0115] Table 1 Designed influent and effluent water quality of a municipal sewage treatment module

[0116]

[0117] S0. Set up the required equipment

[0118] The equipment includes a first reaction tank, a second reaction tank, a third reaction tank and a fourth reaction tank. The effective volume of each tank is 480 m 3 , the four reaction tanks are designed in a "field" grid pattern, and a first aerobic tank and a second aerobic tank are respectively arranged between two adjacent reaction tanks in the horizontal direction; by controlling the four reaction tanks, they can be adjusted into aerobic tanks or anoxic tanks; a total influent pipeline is arranged in both the first reaction tank and the third reaction tank, and a total effluent pipeline is arranged in the second aerobic tank; the residence time of each tank is 1 h, the filling rate of the suspended carriers is 60%, and the concentration of suspended sludge in each reaction tank is < 500 mg / L.

[0119] Adopt operation mode 1, adjust each reaction tank to anoxic tank → anoxic tank → aerobic tank → aerobic tank → first aerobic tank → second aerobic tank to play nitrification and denitrification for nitrogen removal; the nitrogen removal loads of the first and second reaction tanks reach 1.22 and 0.87 gN / m 2 / d respectively; the nitrification loads of the third reaction tank, the fourth reaction tank, the first aerobic tank and the second aerobic tank are 0.57, 0.54, 0.53 and 0.51 gN / m 2 / d respectively.

[0120] S1. Synchronous nitrification and denitrification cultivation in the third reaction tank and the fourth reaction tank

[0121] The DO of the third and fourth reaction pools were increased to 6.57 and 7.56 mg / L respectively. The biofilm thickness of the third and fourth reaction pools was 467 μm and 401 μm respectively. The ammonia nitrogen removal contribution rate reached 92.33%, and the denitrification loads were 0.12 and 0.12 gN / m 2 / d;

[0122] S2, the third reaction tank and the fourth reaction tank anaerobic ammonia oxidation culture

[0123] Switch to operation mode 2, the corresponding operation mode is anoxic pool → anoxic pool → anoxic pool → anoxic pool → first aerobic pool → second aerobic pool;

[0124] Adjust the C / N ratio of the influent to the third reaction tank to 2.5-3.0, and operate until the ammonia nitrogen removal load of the third and fourth reaction tanks reaches 0.17 gN / m 2 / d, 0.13gN / m 2 / d, and the mean relative abundance of anaerobic ammonium oxidizing bacteria were 1.54 and 1.12% respectively;

[0125] S3, simultaneous nitrification and denitrification culture in the first and second reaction tanks

[0126] The first and second reaction tanks were adjusted to aerobic tanks, and the DO of the first and second reaction tanks were increased to 6.37 and 6.97 mg / L respectively. The biofilm thickness of the first and second aerobic tanks reached 512 μm and 439 μm respectively, and the denitrification load reached 0.12 and 0.11 gN / m 2 / d;

[0127] S4, the third and fourth reaction tanks are inoculated with anaerobic ammonia oxidation in the first and second reaction tanks

[0128] Reduce the DO of the first and second reaction pools to 2.14 and 2.01 mg / L, respectively, and operate until the total nitrogen removal load of the first and second reaction pools reaches 0.23 and 0.21 gN / m 2 / d, and the relative abundance of anaerobic ammonium oxidizing bacteria reached 1.21 and 0.95% respectively;

[0129] S5, anaerobic ammonia oxidation oxygen-limited enhancement in the first and second reaction tanks

[0130] The DO of the first and second reaction pools were gradually increased by 0.5-1.0 mg / L. When the DO of the first and second reaction pools reached 3.52 and 3.11 mg / L respectively, the maximum total nitrogen removal load of the two reaction pools reached 0.29 and 0.27 gN / m 2 / d;

[0131] After 96 days of stabilization, the denitrification load from the first reaction tank to the second reaction tank dropped to 0.16 and 0.14 gN / m 2 / d, run steps S6 and S8;

[0132] S6, denitrification and anaerobic ammonium oxidation recovery in the first and second reaction tanks

[0133] Then switch to operation mode 1, and adjust the first and second reaction tanks to anoxic operation, adjust the C / N ratio of the influent of the first reaction tank to 2.5-3.0, and operate until the ammonia nitrogen removal load of the first and second reaction tanks reaches 0.17 gN / m 2 / d, 0.12gN / m 2 / d, and the relative abundance of anaerobic ammonium oxidizing bacteria reached 1.22 and 1.17% respectively;

[0134] S8, anaerobic ammonium oxidation recovery in the third and fourth reaction tanks

[0135] Switch to operation mode 2, and operate the third and fourth reaction tanks in anoxic mode. Adjust the C / N ratio of the influent of the third reaction tank to 2.5-3.0. Operate until the ammonia nitrogen removal load of the third and fourth reaction tanks reaches 0.17 gN / m 2 / d, 0.13gN / m 2 / d, and the relative abundance of anaerobic ammonia-oxidizing bacteria reached 1.21 and 1.16% respectively, and then the process returned to step S5.

[0136] After that, the operation was stable for a long time. During the stable operation period, the inlet water temperature dropped to below 10℃ in winter, and the inlet water TN was 70.38±19.67mg / L, NH4 + -N 50.49±13.60mg / L, effluent TN 2.57±0.53mg / L, NH4 + -N 0.43±0.41mg / L.

[0137] Comparative Example 1:

[0138] A municipal sewage treatment pilot plant with a treatment capacity of 73m 3 / d, the treated water quality was the same as that in Example 1, and the operation was carried out according to the following steps.

[0139] Step 1: Build the necessary equipment

[0140] The equipment includes a first reaction tank, a second reaction tank, a third reaction tank and a fourth reaction tank. The four reaction tanks are designed in a "field" grid pattern. A first aerobic tank and a second aerobic tank are respectively arranged between two adjacent reaction tanks in the horizontal direction. By controlling the four reaction tanks, they can be adjusted into aerobic tanks or anoxic tanks. A total inlet pipeline is arranged in both the first reaction tank and the third reaction tank, and a total outlet pipeline is arranged in the second aerobic tank. The residence time of each tank is 1 h, the filling rate of suspended carriers is 50%, and the concentration of suspended sludge in each reaction tank is <500 mg / L.

[0141] Adopting operation mode 1, adjust each reaction tank to anoxic tank → anoxic tank → aerobic tank → aerobic tank → first aerobic tank → second aerobic tank to achieve nitrification and denitrification nitrogen removal. The denitrification loads of the first and second reaction tanks reach 1.06 and 0.82 gN / m 2 / d respectively; the ammonia oxidation contribution rates of the third and fourth reaction tanks and the first and second aerobic tanks are 29%, 26%, 23% and 22% respectively.

[0142] S1. Simultaneous nitrification and denitrification cultivation of the third and fourth reaction tanks

[0143] Control the DO operation of the third and fourth reaction tanks according to Table 1 and Table 2 respectively. The results show that for the third reaction tank, based on a DO of 6 - 8 mg / L, the biofilm thickness can be >450 μm and 350 μm respectively, and the denitrification load is >0.1 gN / m 2 / d.

[0144] Table 2 Control parameters, final biofilm thickness and denitrification load during the simultaneous nitrification and denitrification cultivation of the biofilm in the third reaction tank

[0145]

[0146] Table 3 Control parameters, final biofilm thickness and denitrification load during the simultaneous nitrification and denitrification cultivation of the biofilm in the fourth reaction tank

[0147]

[0148] Comparative Example 2:

[0149] For the reaction device in Example 1, anaerobic ammonia oxidation cultivation of the third and fourth reaction tanks is carried out in S2 at different DO concentrations.

[0150] Switch to operation mode 2, and the operation mode corresponds to anoxic tank → anoxic tank → anoxic tank → anoxic tank → first aerobic tank → second aerobic tank.

[0151] Adjust the influent C / N of the third reaction tank to 2.5 - 3.0 for operation. The results are shown in Table 3 and Table 4.

[0152] Table 4 Control parameters during the cultivation of biofilm simultaneous nitrification and denitrification in the third reaction tank and the final biofilm thickness and denitrification load

[0153]

[0154] Table 5 Control parameters during the cultivation of biofilm simultaneous nitrification and denitrification in the fourth reaction tank and the final biofilm thickness and denitrification load

[0155]

[0156] It can be seen that before the anaerobic ammonium oxidation biofilm in the third and fourth reaction tanks is acclimated, it is necessary to carry out simultaneous nitrification and denitrification cultivation of the biofilm until the biofilm thickness is greater than 450μm and 350μm respectively, and the denitrification load is greater than 0.1 gN / m 2 / d, so that the thickness of the biofilm increases and an anaerobic / anoxic layer is formed. Otherwise, it is impossible to achieve anaerobic ammonia oxidation denitrification in the anoxic zone by adjusting the anoxic operating parameters.

[0157] Comparative Example 3:

[0158] In the reaction apparatus of Example 1, after completing step S1, the biofilm thicknesses in the third and fourth reaction tanks were 497 and 388 μm, respectively. The apparatus then proceeded to step S2 for anaerobic ammonium oxidation (ANAMMOX) cultivation in the third and fourth reaction tanks. During this period, the C / N ratios of the influent to the third and fourth reaction tanks were adjusted to different values, and the ammonia nitrogen removal load and relative abundance of ANAMMOX bacteria in the third and fourth reaction tanks were observed. As shown in Figure 2, when the influent C / N ratio was <2.5 or >3, the ammonia nitrogen removal load and relative abundance of ANAMMOX bacteria in the third and fourth reaction tanks failed to meet the requirements. This indicates that a stable influent C / N ratio between 2.5 and 3.0 is required for a good ANAMMOX effect in the anoxic zone.

[0159] Comparative Example 4:

[0160] The ammonia nitrogen removal load of the sewage treatment module in comparative example 2 reached 0.16 and 0.12 gN / m3 in the third and fourth reaction tanks respectively. 2 / d, the relative abundance of anaerobic ammonium oxidizing bacteria reached 1.25 and 1.19% respectively. The third and fourth reaction tanks were operated separately as a whole. DO was reduced to 2-4 mg / L. The maximum total nitrogen removal load during operation was only 0.11 and 0.10 gN / m 2 / d, and no anaerobic ammonium oxidizing bacteria were detected in the biofilm.

[0161] It can be seen that after the biofilm is aerobically acclimated, it must be inoculated with anaerobic ammonium oxidation in the anoxic tank, otherwise anaerobic ammonium oxidation denitrification cannot be achieved in the aerobic zone.

[0162] Those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments are within the scope of protection claimed in the present application.

Claims

1. A mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on fluidized bed biofilm, characterized in that, It includes the following steps: S0. Set up the required equipment: The equipment includes four reaction tanks arranged in a "field" shape. In clockwise order, they are the first reaction tank, the second reaction tank, the third reaction tank, and the fourth reaction tank. A first aerobic tank is arranged between the second reaction tank and the fourth reaction tank in the horizontal direction, and a second aerobic tank is arranged between the first reaction tank and the third reaction tank. First water passing corridors, second water passing corridors, and third water passing corridors are respectively arranged on the outer side walls of the first and second reaction tanks, the second and third reaction tanks, and the third and fourth reaction tanks. The first water passing corridor and the second water passing corridor, and the second water passing corridor and the third water passing corridor can communicate with each other; The hydraulic retention time in the first to fourth reaction tanks and the first and second aerobic tanks is 1.0 - 1.5 h, the suspended sludge concentration in the equipment is ≤500 mg / L, and suspended carriers are added to all; The first reaction tank to the fourth reaction tank can be adjusted to be an aerobic tank or an anoxic tank; Through relevant adjustments, the equipment can achieve two operation modes, which are as follows: Operation mode 1: Inflow direction: First reaction tank → Second reaction tank → Second water passing corridor → Third water passing corridor → Third reaction tank → Fourth reaction tank → First aerobic tank → Second aerobic tank; Nitrified liquid flow direction: Second aerobic tank → First reaction tank; Operation mode 2: Inflow direction: Third reaction tank → Fourth reaction tank → Second water passing corridor → First water passing corridor → First reaction tank → Second reaction tank → First aerobic tank → Second aerobic tank; Nitrified liquid flow direction: Second aerobic tank → Third reaction tank; Adopt operation mode 1, adjust the first reaction tank and the second reaction tank to be anoxic tanks, and the third reaction tank and the fourth reaction tank to be aerobic tanks. The operation mode is: anoxic tank → anoxic tank → aerobic tank → aerobic tank → first aerobic tank → second aerobic tank, to achieve nitrification and denitrification for nitrogen removal; the nitrogen removal loads of the first reaction tank and the second reaction tank are respectively greater than 1.0 and 0.8 gN / m 2 / d, or the TN of the effluent from the second reaction tank is < 5 mg / L; the nitrification loads of the third reaction tank, the fourth reaction tank, the first aerobic tank and the second aerobic tank are all greater than 0.5 gN / m 2 / d, or the ammonia nitrogen of the effluent from the second aerobic tank is < 0.5 mg / L; S1. Simultaneous nitrification and denitrification cultivation in the third reaction tank and the fourth reaction tank Increase the DO in the third reaction tank and the fourth reaction tank to 6 - 8 mg / L, and operate until the biofilm thickness in the third reaction tank and the fourth reaction tank is greater than 450 μm and 350 μm respectively, the ammonia nitrogen removal contribution rate > 90%, and the denitrification load > 0.1 gN / m 2 / d; S2. Anaerobic ammonium oxidation cultivation in the third reaction tank and the fourth reaction tank Switch to operation mode 2, and the operation mode corresponds to anoxic tank → anoxic tank → anoxic tank → anoxic tank → first aerobic tank → second aerobic tank; Adjust the influent C / N of the third reaction tank to 2.5 - 3.0, and operate until the ammonia nitrogen removal loads of the third and fourth reaction tanks are respectively greater than 0.15 gN / m 2 / d and 0.10 gN / m 2 / d, and the relative abundances of anaerobic ammonium oxidation bacteria are both > 1.0%; S3. Simultaneous nitrification and denitrification cultivation in the first reaction tank and the second reaction tank Adjust the first reaction tank and the second reaction tank into aerobic tanks, and increase the DO in the first reaction tank and the second reaction tank to 6 - 8 mg / L. Operate until the biofilm thicknesses of the first aerobic tank and the second aerobic tank are greater than 500 μm and 400 μm respectively, and the denitrification loads are both greater than 0.1 gN / m 2 / d; S4. Inoculate the first reaction tank and the second reaction tank with anaerobic ammonium oxidation from the third reaction tank and the fourth reaction tank Reduce the DO in the first reaction tank and the second reaction tank to 2 - 4 mg / L, and operate until the total nitrogen removal load of the first reaction tank and the second reaction tank is greater than 0.2 gN / m 2 / d, and the relative abundances of anaerobic ammonia-oxidizing bacteria are both greater than 0.5%; S5. Oxygen-limited strengthening of anaerobic ammonium oxidation in the first reaction tank and the second reaction tank S6. Restoration of denitrification and anaerobic ammonium oxidation in the first reaction tank and the second reaction tank S7. Restoration of simultaneous nitrification and denitrification in the third reaction tank and the fourth reaction tank S8. Restoration of anaerobic ammonium oxidation in the third reaction tank and the fourth reaction tank 2. The mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on fluidized bed biofilm according to claim 1, wherein The specific adjustment method in step S5 is: gradually increase the DO in the first reaction tank and the second reaction tank by 0.5 - 1.0 mg / L, and operate until the sum of the nitrogen removal loads in the first reaction tank and the second reaction tank reaches the highest, and the relative abundances of anaerobic ammonium oxidation bacteria are both >1.0%; If the decline in the nitrogen removal load or the relative abundance of anaerobic ammonium oxidation bacteria in the first reaction tank to the second reaction tank exceeds 30%, then operate S6 and S8. If the decline in the ammonia nitrogen removal load or the relative abundance of anaerobic ammonium oxidation bacteria in the third to fourth reaction tanks exceeds 30%, then operate S7 and S8.

3. The mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on fluidized bed biofilm according to claim 1, characterized in that, The specific adjustment method in step S6 is as follows: Switch to operation mode 1, adjust the first reaction tank and the second reaction tank to operate under anoxic conditions, adjust the influent C / N of the first reaction tank to be 2.5 - 3.0, and operate until the ammonia nitrogen removal loads of the first reaction tank and the second reaction tank are respectively greater than 0.15 gN / m 2 / d and 0.10 gN / m 2 / d, and the relative abundances of anaerobic ammonia-oxidizing bacteria are both > 1.0%.

4. The mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on fluidized bed biofilm according to claim 1, characterized in that, The specific adjustment method for step S7 is as follows: increase the DO in the third reaction tank and the fourth reaction tank to 6 - 8 mg / L, and operate until the biofilm thickness in the third reaction tank and the fourth reaction tank is greater than 500 μm and 400 μm respectively, and the denitrification load is greater than 0.1 gN / m 2 / d.

5. The mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on fluidized bed biofilm according to claim 1, wherein The specific adjustment method in step S8 is as follows: Switch to operation mode 2, and the third and fourth reaction tanks operate under anoxic conditions until the ammonia nitrogen removal loads of the third and fourth reaction tanks are respectively greater than 0.15 gN / m 2 / d and 0.10 gN / m 2 / d, and the relative abundances of anaerobic ammonia-oxidizing bacteria are both > 1.0%; then return to step S5 for operation.

6. The mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on fluidized bed biofilm according to claim 1, characterized in that, Stirring devices and aeration pipelines are provided in the first reaction tank, the second reaction tank, the third reaction tank and the fourth reaction tank. By starting the stirring devices, each reaction tank can be adjusted to an anoxic tank, and by starting the aeration devices, each reaction tank can be adjusted to an aerobic tank.

7. The mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on fluidized bed biofilm according to claim 1, characterized in that: The first reaction tank is connected to a first main inlet pipeline, the third reaction tank is connected to a second main inlet pipeline, and the second aerobic tank is connected to a main outlet pipeline; a first water passing gate and a second water passing gate are respectively arranged at both ends of the second water passing corridor.

8. The mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on fluidized bed biofilm according to claim 1, characterized in that: Intercepting screens are arranged in front of the water outlet ends of each reaction tank, and adjacent reaction tanks are kept connected through water passing openings; a first nitrification liquid reflux pump and a second nitrification liquid reflux pump are arranged behind the intercepting screen of the second aerobic tank.

9. The mainstream anaerobic ammonium oxidation enhanced nitrogen removal method based on fluidized bed biofilm according to claim 1, characterized in that: When setting up the required equipment, the shape of the floating carriers is flat cylindrical porous honeycomb, and the effective specific surface area ≥ 620 m 2 / m 3 , the filling rate of the floating carriers is greater than 45%; the density of the floating carriers in the first reaction tank and the second reaction tank is 0.97 - 1.00 g / cm 3 , the average void spacing of the floating carriers ≥ 3 mm, and the density of the floating carriers in the third reaction tank and the fourth reaction tank is 1.00 - 1.03 g / cm 3 , the average void spacing of the floating carriers ≥ 4 mm, and the density of the floating carriers in the first aerobic tank and the second aerobic tank is 0.94 - 0.97 g / cm 3 , the average void spacing of the floating carriers ≥ 5 mm; the temperature for the equipment to treat sewage ≥ 10 °C, C / N ≥ 3; in steps S0 to S8, the ammonia nitrogen and total nitrogen in the effluent of the equipment need to be less than 0.5 mg / L and 5 mg / L respectively; the method for adjusting C / N in step S2 is to adjust the reflux ratio and introduce raw water into the third reaction tank at 0 - 10% of the influent flow rate of the equipment; the methods for adjusting C / N in steps S6 and S8 refer to adjusting the reflux ratio.

10. The mainstream anaerobic ammonium oxidation enhanced nitrogen removal equipment based on fluidized bed biofilm is characterized in that: The equipment includes four reaction tanks arranged in a "field" shape, which are the first reaction tank, the second reaction tank, the third reaction tank and the fourth reaction tank in the clockwise direction. A first aerobic tank is arranged between the second reaction tank and the fourth reaction tank in the horizontal direction, and a second aerobic tank is arranged between the first reaction tank and the third reaction tank. First water passing corridors, second water passing corridors and third water passing corridors are respectively arranged on the outer pool walls of the first and second reaction tanks, the second and third reaction tanks, and the third and fourth reaction tanks. The first water passing corridor and the second water passing corridor, and the second water passing corridor and the third water passing corridor can communicate with each other; The hydraulic retention times in the first to fourth reaction tanks and the first and second aerobic tanks are all 1.0 - 1.5 h, the suspended sludge concentration in the equipment is ≤ 500 mg / L, and suspended carriers are added. The first to fourth reaction tanks can be adjusted to aerobic tanks or anoxic tanks. Aeration devices and stirring devices are arranged in the first to fourth reaction tanks. By starting the stirring devices, the corresponding reaction tanks are adjusted to anoxic tanks, and by starting the aeration devices, the corresponding reaction tanks are adjusted to aerobic tanks.

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