Method for using migratable biofilm-based autotrophic nitrogen removal device

Abstract

A method for using a migratable biofilm-based autotrophic nitrogen removal device, the method comprising the steps of device construction, aerobic biofilm thickness enhancement, anammox acclimation of an anoxic biofilm, anoxic / aerobic carrier migration, anammox aerobic culture, anammox aerobic enhancement, etc. After the device is successfully started, the overall load of mainstream anammox can reach more than 0.65 gN / m2 / d, and the nitrogen removal contribution rate can reach more than 50%, such that the dependence of low carbon-to-nitrogen ratio sewage denitrification on an externally added carbon source is eliminated, and the aeration energy consumption is reduced by over 20%. In addition, anammox enrichment start-up can be achieved on the basis of normal operation of a process, and the water quality of an effluent during suspended carrier migration always maintains high standards of ammonia nitrogen<0.5 mg / L and TN<5 mg / L, so that the anammox start-up time, device and labor costs are reduced, thereby avoiding exceedance of water quality standards or operation at reduced capacity caused by the start-up of anammox.

Description

Method for using a transportable biofilm autotrophic denitrification equipment Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a method for using a transportable biofilm autotrophic denitrification device. Background Art

[0002] At present, the sewage treatment process has problems such as high energy consumption of nitrification aeration and excessive addition of denitrification carbon sources, which has caused the sewage treatment industry to rank among the top ten high-carbon emission industries in China. Therefore, it is necessary to optimize and improve the existing sewage treatment process to achieve green and low-carbon sewage treatment.

[0003] Compared to traditional nitrification and denitrification, the anaerobic ammonium oxidation (ANAMMOX) process can save over 60% of aeration volume and 100% of carbon source addition, achieving green and low-carbon wastewater treatment. However, it is currently primarily used to treat high-ammonia nitrogen wastewater. Application to mainstream urban sewage treatment plants often faces challenges such as low substrate concentration, large fluctuations in water quality, and low sewage temperature. This makes it difficult to enrich ANAMMOX bacteria, resulting in long startup cycles. Even after successful startup, ANAMMOX bacteria face the risk of continued degradation, making long-term stable operation difficult. Therefore, implementing the ANAMMOX process in mainstream urban sewage treatment remains an industry challenge.

[0004] Currently, in order to achieve the startup and operation of anaerobic ammonium oxidation in mainstream municipal wastewater treatment, the relevant research reports on existing technologies are as follows:

[0005] CN113735264A discloses a rapid start-up method for an autotrophic denitrification process of a mud-film mixed moving bed biofilm reactor, which first inoculates short-range nitrification flocculent sludge, adds suspended fillers, and constitutes an MBBR reactor. At room temperature, the ratio of the influent ammonia nitrogen concentration and the nitrous oxide concentration is controlled, and the short-range is maintained at a higher aeration rate. The anoxic time is appropriately increased to successfully enrich anaerobic ammonia oxidizing bacteria. After starting the anaerobic ammonia oxidation reaction, the aeration rate is gradually reduced to reduce DO, the aeration time is increased, and aerobic ammonia oxidizing bacteria and AnAOB are induced to simultaneously perform short-range nitrification and anaerobic ammonia oxidation reactions during the aeration stage. It has the following problems: first, it is necessary to artificially add nitrous oxide to the influent and control the corresponding ratio, which does not really solve the problem of the nitrous oxide source of the anaerobic ammonia oxidation reaction. The reagent consumption is large and it is difficult to achieve in engineering. Secondly, the system DO during the startup process fluctuates up and down, so it is impossible to ensure that the system has a good nitrification effect all the time, and it is difficult to ensure that the effluent during the startup is stable and meets the standards or is running at full water volume.

[0006] CN107253762B discloses a rapid start-up method for short-range denitrification and phosphorus removal coupled with anaerobic ammonium oxidation, which is connected in series with an AAO reactor and an MBBR reactor, and starts short-range nitrification by inoculating an anaerobic ammonium oxidation suspended carrier in the AAO anoxic tank and inoculating short-range nitrification sludge in the MBBR tank, and provides a nitrite substrate for anaerobic ammonium oxidation through reflux, thereby achieving autotrophic denitrification. It has the following problems: First, short-range nitrification and anaerobic ammonium oxidation are both achieved by inoculation, which does not really solve the core bottleneck of mainstream anaerobic ammonium oxidation and is difficult to implement effectively for large-scale engineering projects; second, in some system details, the suspended carrier uses a density of 0.20 to 0.25 g / cm 3 The carrier density is lower than that of water, and anaerobic ammonia oxidation denitrification itself easily produces steam, causing the carrier to float. Under the premise of low carrier density, it is easy for the carrier to accumulate on the pool surface, making it difficult to achieve uniform fluidization in the entire pool, or the fluidization power required to achieve uniform fluidization is too high.

[0007] This suggests that existing technologies for anaerobic ammonium oxidation (ANAMMOX) denitrification of mainstream municipal wastewater primarily rely on dosing mechanisms and inoculation with established, mature bacterial strains. These technologies have yet to truly overcome the bottlenecks of mainstream ANAMMOX, and in actual operation, they struggle to achieve stable bacterial strain retention. Therefore, existing technologies require further improvement. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for using a transportable biofilm autotrophic denitrification equipment, which can realize the enrichment start-up of anaerobic ammonia oxidation on the basis of normal process operation. After successful start-up, the overall mainstream anaerobic ammonia oxidation load of the equipment can reach 0.65gN / m 2 / d or more, the denitrification contribution rate can reach more than 50%, getting rid of the dependence on external carbon sources for denitrification of low carbon-nitrogen ratio sewage; at the same time, it reduces aeration energy consumption by more than 20%.

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

[0010] A method for using a transportable biofilm autotrophic denitrification device comprises the following steps:

[0011] Step 1, the equipment includes a first reaction tank, a second reaction tank, a third reaction tank, a fourth reaction tank and a fifth reaction tank arranged in sequence from front to back, a total water inlet pipe is provided at the front end of the first reaction tank, and a total water outlet pipe is provided at the end of the fifth reaction tank; interception screens are provided at the ends of the first reaction tank, the second reaction tank, the third reaction tank, the fourth reaction tank and the fifth reaction tank;

[0012] The first and second reaction tanks are equipped with stirring devices, and the third, fourth and fifth reaction tanks are equipped with aeration devices. Suspended carriers are added to each reaction tank. The TN removal load of the first and second reaction tanks is greater than 1.0 N / m 2 / d, 0.5gN / m 2 / d; the ammonia oxidation load of the third reaction tank is greater than 1.0gN / m 2 / d, TN removal load greater than 0.1gN / m 2 / d, average biofilm thickness greater than 500 μm;

[0013] Step 2: Strengthening the thickness of aerobic biofilm

[0014] After the fourth reaction tank and the fifth reaction tank meet all the following conditions through relevant control operations, proceed to step 3;

[0015] The average biofilm thickness of the fourth reaction tank is greater than 500 μm and the average biofilm thickness of the fifth reaction tank is greater than 400 μm, and the ammonia oxidation load of the fourth reaction tank is greater than 1.0 gN / m 2 / d and the ammonia oxidation load of the fifth reaction tank is greater than 0.8gN / m 2 / d;

[0016] The TN removal loads of the fourth and fifth reaction tanks were both greater than 0.1 gN / m 2 / d;

[0017] Step 3: Anaerobic ammonium oxidation acclimation of anoxic biofilm

[0018] After the first reaction tank and the second reaction tank meet all the following conditions through relevant control, proceed to step 4;

[0019] The average nitrous oxide concentration in the first and second reaction tanks was greater than 0.5 mg / L for 15 consecutive days;

[0020] The ammonia nitrogen removal load of the first reaction tank is greater than 0.1 gN / m 2 / d and the ammonia nitrogen removal load of the second reaction tank is greater than 0.05gN / m 2 / d;

[0021] The relative abundance of anaerobic ammonium oxidizing bacteria in the first reaction tank is greater than 1.0% and the relative abundance of anaerobic ammonium oxidizing bacteria in the second reaction tank is greater than 0.5%;

[0022] Step 4: Anoxic / Aerobic Carrier Migration

[0023] Through relevant control, the suspended carrier flows from the first reaction tank to the second reaction tank, the second reaction tank to the third reaction tank, the third reaction tank to the fourth reaction tank, the fourth reaction tank to the fifth reaction tank, and the fifth reaction tank flows to the first reaction tank through the water gallery until it completes 0.2 to 0.4 HRT migration and returns to the state before migration;

[0024] Step 5: Anaerobic ammonium oxidation aerobic culture

[0025] After the system runs stably and the following conditions are met simultaneously, it proceeds to step 6:

[0026] The average nitrous oxide concentration in the first reaction tank was greater than 0.5 mg / L for 15 consecutive days;

[0027] The ammonia nitrogen removal load of the first reaction tank is greater than 0.1 gN / m 2 / d, the ammonia nitrogen removal load of the second reaction tank is greater than 0.05gN / m 2 / d;

[0028] The TN removal load of the third reaction tank is greater than 0.2 gN / m 2 / d;

[0029] Step 6: Anaerobic ammonia oxidation aerobic enhancement

[0030] Gradually increase the DO of the third reaction tank to 4-6 mg / L and operate until the load of the third reaction tank is stable > 0.2 gN / m for 5 consecutive days. 2 / d or more, repeat steps 4 to 6 to complete the migration of 3 HRTs;

[0031] Step 7: The equipment runs stably.

[0032] The above-mentioned method for using a transportable biofilm autotrophic denitrification equipment, in step one, is provided with a first gate on the interception screen of the first reaction tank, a second gate on the interception screen of the second reaction tank, a third gate on the interception screen of the third reaction tank, and a fourth gate on the interception screen of the fourth reaction tank. By opening the first gate, the second gate, the third gate or the fourth gate, the suspended carrier in the corresponding reaction tank can flow to the next reaction tank.

[0033] The above-mentioned method for using a portable biofilm autotrophic denitrification equipment, the first reaction tank and the fifth reaction tank are connected by a water gallery, a first water gate is provided on the water gallery side of the first reaction tank, a second water gate and a third water gate are respectively provided on the front and rear end water gallery sides of the interception screen of the fifth reaction tank, the stirring device in the fifth reaction tank is installed on the opposite side of the second water gate, and a liftable water outlet weir is provided behind the interception screen of the fifth reaction tank.

[0034] In the method for using the above-mentioned transportable biofilm autotrophic denitrification equipment, in step one, the aeration device is a perforated aeration device with an opening diameter of 4 to 6 mm; the MLSS of the suspended carrier is <500 mg / L, the average pore diameter of the suspended carrier is >5 mm, and the filling rate of the suspended carrier is 30% to 67%.

[0035] The above-mentioned method for using the transportable biofilm autotrophic denitrification equipment is as follows: the installation height of the stirring device in the fifth reaction tank is higher than 50% of the water depth and does not exceed the liquid surface; the lifting height of the liftable outlet weir should be greater than 50% of the height of the second water gate; the aperture of the intercepting screen in each reaction tank is 50%~80% of the corresponding suspended carrier diameter.

[0036] The above-mentioned method for using the mobile biofilm autotrophic denitrification equipment, wherein the power density of the stirring device in the first reaction tank and the second reaction tank is 5-15W / m 3 ; The DO of the third reaction tank is 6~8mg / L, and the DO of the fourth reaction tank and the fifth reaction tank are both 4~6mg / L.

[0037] In the above-mentioned method for using a transportable biofilm autotrophic denitrification equipment, in step two, the related control refers to: reducing the aeration of the third reaction tank until the ammonia nitrogen loss is less than 15%, and increasing the DO of the fourth reaction tank; in step three, through related control refers to increasing the flow rate and reflux ratio in the first reaction tank and the second reaction tank.

[0038] The above-mentioned method for using a transportable biofilm autotrophic denitrification equipment, in step four, through relevant control means: raising the liquid level from the first reaction tank to the fifth reaction tank, opening the first gate to the fourth gate, closing the third water gate, opening the second water gate and opening the stirring device of the fifth reaction tank, at this time the suspended carrier flows from the first reaction tank to the second reaction tank, the second reaction tank flows to the third reaction tank, the third reaction tank flows to the fourth reaction tank, the fourth reaction tank flows to the fifth reaction tank, and the fifth reaction tank flows to the first reaction tank through the water gallery; the specific steps of step seven for stable operation of the equipment are: the equipment maintains stable operation every 3 months or when any value of the ammonia oxidation load of the first and second reaction tanks or the TN removal load of the third and fourth reaction tanks decreases by more than 30%, repeating steps one to seven; in steps one to seven, the effluent ammonia nitrogen and TN of the equipment are stably less than 0.5 mg / L and 5 mg / L respectively.

[0039] The above-mentioned method for using a portable biofilm autotrophic denitrification equipment is as follows: in step 2, the DO of the third reaction tank is controlled at 2~4 mg / L, and the DO of the fourth reaction tank and the fifth reaction tank is controlled at 6~8 mg / L; in step 3, the average flow rate is gradient-enhanced, the gradient is 0.05~0.1 m / s, the reflux ratio is gradient-enhanced, the gradient is 30%~50%, and each gradient lasts for 5 days; in step 4, when the anoxic / aerobic carrier migrates, the liquid level of the fifth reaction tank exceeds the lowest point of the second water gate by more than 50%; in step 5, the DO of the third reaction tank is controlled at 2~4 mg / L, and the aeration intensity is controlled at 4~6m 3 / m 2 / h, the fourth reaction tank controls DO at 4~6mg / L, and the aeration intensity is>10m 3 / m 2 / h, the fifth reaction tank controls DO at 8~10mg / L, and the aeration intensity is>12m 3 / m 2 / h; in step six, maintain the third reaction tank TN removal load> 0.2gN / m 2 / d, the DO of the third reaction tank was increased by a gradient of 0.5 mg / L, and the DO of the fifth reaction tank was reduced to 6~8 mg / L by the same gradient.

[0040] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0041] 1) Energy saving and consumption reduction. After the successful startup of the present invention, the overall load of the mainstream anaerobic ammonium oxidation equipment can reach 0.65gN / m 2 / d or more, the denitrification contribution rate can reach more than 50%, getting rid of the dependence on external carbon sources for denitrification of low carbon-nitrogen ratio sewage; at the same time, it reduces aeration energy consumption by more than 20%;

[0042] 2) High standards. The method of the present invention can achieve enrichment startup of anaerobic ammonium oxidation on the basis of normal operation. The effluent water quality during the suspended carrier migration process always maintains high standards of ammonia nitrogen <0.5mg / L and TN <5mg / L, which reduces the time, equipment and labor costs of anaerobic ammonium oxidation startup and avoids water quality exceeding the standard or reduced operation due to the startup of anaerobic ammonium oxidation;

[0043] 3) Strong stability. The present invention provides a method for maintaining the anaerobic ammonium oxidation effect of the equipment over the long term. After successful startup, the anaerobic ammonium oxidation load maintenance rate can be stabilized at more than 70%, and the minimum application temperature can reach 10°C, overcoming the problem of difficult and stable operation of the anaerobic ammonium oxidation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention will be further described below with reference to the accompanying drawings:

[0045] FIG1 is a schematic structural diagram of the equipment of the present invention;

[0046] Figure 2 shows the changes in the load and relative abundance of anaerobic ammonia-oxidizing bacteria in the third reaction tank III and the fourth reaction tank IV of Comparative Example 2;

[0047] In the figure: I, first reaction tank, II, second reaction tank, III, third reaction tank, IV, fourth reaction tank, V, fifth reaction tank, I1, main water inlet pipeline, I2, main water outlet pipeline, S1, interception screen of the first reaction tank, S2, interception screen of the second reaction tank, S3, interception screen of the third reaction tank, S4, interception screen of the fourth reaction tank, S5, interception screen of the fifth reaction tank, N1, first gate, N2, second gate, N3, third gate, N4, fourth gate, f1, first water gate, f2, second water gate, f3, third water gate, J, stirring device, g, water gallery, Y, liftable outlet weir. DETAILED DESCRIPTION

[0048] 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.

[0049] 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.

[0050] The structures and operating principles of the stirring device and aeration device described in the present invention can be implemented by those skilled in the art by referring to existing technologies.

[0051] The technical solution of the present application is further described in detail below with reference to the accompanying drawings.

[0052] The following explanations are given for the specific terms used in the present invention:

[0053] Ammonia nitrogen removal load: the amount of ammonia nitrogen removed by the biofilm per unit area per unit time, gN / m 2 / d;

[0054] TN removal load: the amount of TN removed by the biofilm per unit area per unit time, gN / m 2 / d;

[0055] HRT: hydraulic retention time, the average residence time of the wastewater to be treated in the reaction tank, h;

[0056] Relative abundance of anaerobic ammonium oxidizing bacteria: the ratio of the number of anaerobic ammonium oxidizing bacteria to the total number of bacteria, %;

[0057] DO: Dissolved oxygen, molecular oxygen dissolved in water, mg / L.

[0058] The technical solution of the present application is further described in detail below with reference to the accompanying drawings.

[0059] As shown in Figure 1, the equipment of the present invention includes a first reaction tank I, a second reaction tank II, a third reaction tank III, a fourth reaction tank IV and a fifth reaction tank V connected in sequence. The front end of the first reaction tank is provided with a total water inlet pipeline I1, and the end of the fifth reaction tank is provided with a total water outlet pipeline I2; interception screens are provided at the ends of the first reaction tank, the second reaction tank, the third reaction tank, the fourth reaction tank and the fifth reaction tank, which are respectively the interception screen S1 of the first reaction tank, the interception screen S2 of the second reaction tank, the interception screen S3 of the third reaction tank, the interception screen S4 of the fourth reaction tank and the interception screen S5 of the fifth reaction tank; a first gate N1 is provided on the interception screen S1 of the first reaction tank, a second gate N2 is provided on the interception screen S2 of the second reaction tank, and a second gate N1 is provided on the interception screen S2 of the third reaction tank. A third gate N3 is provided on S3, a fourth gate N4 is provided on the intercepting screen S4 of the fourth reaction tank, the first reaction tank and the fifth reaction tank are connected by a water gallery g, a first water gallery f1 is provided on the water gallery side of the first reaction tank, a second water gallery f2 and a third water gallery f3 are provided on the water gallery sides at the front and rear ends of the screen of the fifth reaction tank, respectively, a stirring device J is provided in the first and second reaction tanks, an aeration device is provided in the third, fourth and fifth reaction tanks, a liftable outlet weir Y is provided behind the intercepting screen of the fifth reaction tank, suspended carriers are added to each reaction tank, MLSS < 500 mg / L, the average pore diameter of the suspended carriers is > 5 mm, and the TN removal loads of the first and second reaction tanks are respectively greater than 1.0 N / m 2 / d, 0.5gN / m 2 / d, the ammonia oxidation load of the third reaction tank is greater than 1.0gN / m 2 / d, TN removal load greater than 0.1gN / m 2 / d.

[0060] The denitrification method of the present invention is described in detail in conjunction with the above equipment.

[0061] The denitrification method of the present invention mainly includes: 1. Equipment construction, ensuring that the effluent is stable and meets the standards, completing the biofilm formation in the third reaction tank, and providing conditions for the biofilm formation in the fourth and fifth reaction tanks; 2. Aerobic biofilm thickness enhancement, performing biofilm enhancement in the fourth and fifth reaction tanks, achieving the enrichment of internal denitrifying bacteria based on the biofilm thickness, ensuring the anoxic denitrification effect after the carrier migration, and laying the foundation for the enrichment of anaerobic ammonia oxidation; 3. Anaerobic ammonia oxidation acclimation of anoxic biofilm, first achieving the enrichment of anaerobic ammonia oxidation bacteria in the anoxic zone, and providing the foundation for the subsequent carrier migration; 4. Anoxic / aerobic carrier ⑤ Anaerobic culture of anaerobic ammonium oxidation: the third reaction tank carries out low-DO anaerobic ammonium oxidation culture to prevent high-DO inhibition, while the fifth reaction tank ensures the nitrification effect; ⑥ Aerobic enhancement of anaerobic ammonium oxidation: the third reaction tank strengthens the DO tolerance of aerobic anaerobic ammonium oxidation by gradually increasing DO, providing a basis for further migration to the high-DO IV reaction tank; ⑦ Stable operation of the equipment: by regularly repeating the above steps, the anaerobic ammonium oxidation effect in the equipment is always maintained at more than 70% of the maximum value.

[0062] The specific steps are as follows:

[0063] Step 1: Build the above equipment;

[0064] Step 2: Strengthening the thickness of aerobic biofilm

[0065] Reduce the aeration of the third reaction tank until the ammonia nitrogen loss is less than 15%, and increase the DO of the fourth reaction tank. Once the fourth and fifth reaction tanks meet all the following conditions, proceed to step 3;

[0066] The average biofilm thickness of the fourth reaction tank is greater than 500 μm and the average biofilm thickness of the fifth reaction tank is greater than 400 μm, and the ammonia oxidation load of the fourth reaction tank is greater than 1.0 gN / m 2 / d and the ammonia oxidation load of the fifth reaction tank is greater than 0.8gN / m 2 / d;

[0067] The TN removal loads of the fourth and fifth reaction tanks were both greater than 0.1 gN / m 2 / d;

[0068] Step 3: Anaerobic ammonium oxidation acclimation of anoxic biofilm

[0069] Increase the flow rate and reflux ratio in the first reaction pool and the second reaction pool so that the first reaction pool and the second reaction pool meet all the following conditions, and then proceed to step 4;

[0070] The average nitrous oxide concentration in the first and second reaction tanks was greater than 0.5 mg / L for 15 consecutive days;

[0071] The ammonia nitrogen removal load of the first reaction tank is greater than 0.1 gN / m 2 / d and the ammonia nitrogen removal load of the second reaction tank is greater than 0.05gN / m 2 / d;

[0072] The relative abundance of anaerobic ammonium oxidizing bacteria in the first reaction tank is greater than 1.0% and the relative abundance of anaerobic ammonium oxidizing bacteria in the second reaction tank is greater than 0.5%;

[0073] Step 4: Anoxic / Aerobic Carrier Migration

[0074] Raise the liquid level from the first reaction tank to the fifth reaction tank, open the first gate to the fourth gate, close the third water gate, open the second water gate and start the stirring device. At this time, the suspended carrier flows from the first reaction tank to the second reaction tank, the second reaction tank to the third reaction tank, the third reaction tank to the fourth reaction tank, the fourth reaction tank to the fifth reaction tank, and the fifth reaction tank to the first reaction tank through the water gallery until it completes 0.2 to 0.4 HRT migration and returns to the state before migration;

[0075] Step 5: Anaerobic ammonium oxidation aerobic culture

[0076] After the system runs stably and the following conditions are met simultaneously, it proceeds to step 6:

[0077] The average nitrous oxide concentration in the first reaction tank was greater than 0.5 mg / L for 15 consecutive days;

[0078] The ammonia nitrogen removal load of the first reaction tank is greater than 0.1gN / m 2 / d, the ammonia nitrogen removal load of the second reaction tank is greater than 0.05gN / m 2 / d;

[0079] The TN removal load of the third reaction tank is greater than 0.2 gN / m 2 / d;

[0080] Step 6: Anaerobic ammonia oxidation aerobic enhancement

[0081] Gradually increase the DO of the third reaction tank to 4-6 mg / L and operate until the load of the third reaction tank is stable > 0.2 gN / m for 5 consecutive days. 2 / d or more, repeat steps 4 to 6 to complete the migration of 3 HRTs;

[0082] Step 7. The equipment maintains stable operation. Repeat steps 1 to 7 every 3 months or when any of the ammonia oxidation loads of the first and second reaction tanks or the TN removal loads of the third and fourth reaction tanks decreases by more than 30%. In steps 1 to 7, the ammonia nitrogen and TN in the effluent of the equipment are stably less than 0.5 mg / L and 5 mg / L, respectively.

[0083] Preferably, in step 1, the aeration device is a perforated aeration device with a hole diameter of 4 to 6 mm.

[0084] Preferably, the installation height of the stirring device is higher than 50% of the water depth and does not exceed the liquid surface; the lifting height of the water outlet weir should be greater than 50% of the height of the second water gate; the aperture of the intercepting screen in each reaction tank is 50% to 80% of the corresponding suspended carrier diameter.

[0085] Preferably, the power density of the stirring device in the first reaction tank and the second reaction tank is 5~15W / m 3 ; The DO of the third reaction tank is 6~8mg / L, and the DO of the fourth reaction tank and the fifth reaction tank are both 4~6mg / L.

[0086] Preferably, in step 2, the DO of the third reaction tank is controlled at 2-4 mg / L, and the DO of the fourth and fifth reaction tanks are controlled at 6-8 mg / L; in step 3, the average flow rate is a gradient increase with a gradient of 0.05-0.1 m / s, the reflux ratio is a gradient increase with a gradient of 30%-50%, and each gradient lasts for 5 days; in step 4, when the anoxic / aerobic carrier migrates, the liquid level of the fifth reaction tank exceeds the lowest point of the second water gate by more than 50%; in step 5, the DO of the third reaction tank is controlled at 2-4 mg / L, and the aeration intensity is controlled at 4-6 m 3 / m 2 / h, the fourth reaction tank controls DO at 4~6mg / L, and the aeration intensity is>10m 3 / m 2 / h, the fifth reaction tank controls DO at 8~10mg / L, and the aeration intensity is>12m 3 / m 2 / h; in step six, maintain the third reaction tank TN removal load> 0.2gN / m 2 / d, the DO of the third reaction tank was increased by a gradient of 0.5 mg / L, and the DO of the fifth reaction tank was reduced to 6~8 mg / L by the same gradient.

[0087] The present invention is described in detail below with reference to specific embodiments. Example

[0088] A municipal sewage treatment module, designed to treat 1.0×10 4 m 3 / d, the designed inlet water quality is shown in Table 1, and the operation is carried out according to the following steps.

[0089] Table 1 Design of inlet and outlet water quality for a municipal sewage treatment module

[0090]

[0091] S1) Equipment Construction:

[0092] The sewage treatment module includes the first reaction tank, the second reaction tank, the third reaction tank, the fourth reaction tank and the fifth reaction tank, which are arranged in sequence. The effective capacity of each tank is 625m 3 The total HRT of the equipment is 7.5h. An interception screen is set at the end of each reaction tank. A gate is set on the interception screen from the first reaction tank to the fourth reaction tank. The first reaction tank and the fifth reaction tank are connected by a water corridor. A first water gate is set on the water corridor side of the first reaction tank. A second water gate and a third water gate are set on the water corridor side of the front and rear ends of the screen of the fifth reaction tank respectively. The gate height is 50cm. An agitator is installed opposite the second water gate. A liftable water weir is set behind the interception screen of the fifth reaction tank. The liftable height is 30cm. A stirring device is set in the first reaction tank and the second reaction tank. The stirring power density is 7.5W / m 3 The third, fourth and fifth reaction tanks are equipped with perforated aeration devices with a diameter of 4mm. Suspended carriers are added to each reaction tank. The average pore diameter of the suspended carriers is 5mm and the effective specific surface area is 620m 2 / m 3 The filling rate is 55%, and the MLSS in the equipment is less than 500mg / L; the DO of the third reaction tank is controlled at 6~8mg / L, and the TN removal loads of the first and second reaction tanks are 1.2 and 0.55gN / m respectively. 2 / d; the ammonia oxidation load of the third reaction tank III is 1.3gN / m 2 / d, the biofilm thickness reached 510 μm, and the TN removal load was 0.15 gN / m 2 / d; effluent ammonia nitrogen ≤ 0.5 mg / L, effluent TN ≤ 5 mg / L;

[0093] S2) Aerobic biofilm thickness enhancement:

[0094] The DO of the third reaction tank was reduced to 2~4 mg / L, the ammonia nitrogen loss was reduced to 10%, and the DO of the fourth and fifth reaction tanks was increased to 6~8 mg / L. The average biofilm thickness of the fourth and fifth reaction tanks was increased to 525μm and 433μm, respectively, and the ammonia oxidation load was 1.3 and 0.91 gN / m 2 / d, and the TN removal load was 0.15 gN / m 2 / d, 0.11gN / m 2 / d, during this process, the effluent ammonia nitrogen is ≤0.5 mg / L, and the effluent TN is ≤5 mg / L, and the process proceeds to step S3;

[0095] S3) Anaerobic ammonium oxidation acclimation of anoxic biofilms:

[0096] The flow rate (0.5 m / s) and reflux ratio (250%) in the first and second reaction tanks were gradually increased until the average nitrous oxide concentration in the first and second reaction tanks was > 0.5 mg / L for 15 consecutive days (the actual value was 0.61 mg / L). At this time, the ammonia nitrogen removal loads in the first and second reaction tanks were 0.13 and 0.07 gN / m 2 / d, the dominant anaerobic ammonia-oxidizing bacteria is Candidatus Brocadia, with relative abundances of 1.6% and 0.9%, respectively. In this process, the effluent ammonia nitrogen is ≤0.5 mg / L, and the effluent TN is ≤5 mg / L, and the process proceeds to step S4;

[0097] S4) Anoxic / Aerobic Carrier Migration:

[0098] The liquid level in each reaction tank is raised by 30 cm, the intercepting screen gate is opened, the third water gate is closed, the second water gate is opened, and the agitator of the fifth reaction tank is turned on. The suspended carrier in each tank is allowed to flow to the next tank in sequence. After completing 0.4 HRT migration, the state is restored to the pre-migration state. During this process, the effluent ammonia nitrogen is ≤ 0.5 mg / L and the effluent TN is ≤ 5 mg / L, and the process proceeds to step S5.

[0099] S5) Anaerobic ammonium oxidation aerobic culture:

[0100] Maintain stable operation until the average nitrous oxide concentration in the first reaction pool is > 0.5 mg / L for 15 consecutive days (actually 0.55 mg / L). At this time, the ammonia nitrogen removal loads in the first and second reaction pools are 0.16 and 0.09 gN / m 2 / d, the TN removal load of the third reaction tank is 0.25gN / m 2 / d, during this process, the effluent ammonia nitrogen is ≤0.5 mg / L, and the effluent TN is ≤5 mg / L, and the process proceeds to step S6;

[0101] S6) Anaerobic ammonium oxidation aerobic enhancement:

[0102] Gradually increase the DO of the third reaction tank to 4~6mg / L and operate until the TN removal load of the third reaction tank is stable >0.2gN / m for 5 consecutive days. 2 / d or above (actually 0.22~0.26gN / m 2 / d), repeat steps S4 to S6 to complete the migration of 3 HRTs;

[0103] S7) Stable operation:

[0104] The ammonia nitrogen removal loads of the first and second reaction tanks in the equipment are 0.15 and 0.09 gN / m respectively. 2 / d, the TN removal loads of the third and fourth reaction tanks were 0.27 and 0.21 gN / m 2 / d, and repeat steps S1 to S7 every three months or when any of the ammonia oxidation loads of the first and second reaction tanks or the TN removal loads of the third and fourth reaction tanks drops by more than 30% to maintain a stable load. The equipment has been running stably for more than two years, and the maximum anaerobic ammonia oxidation load has reached 0.86 gN / m 2 / d, aeration energy consumption is reduced by more than 30%. When the water temperature reaches 8.5℃ in winter, the anaerobic ammonia oxidation load is still guaranteed to reach more than 70% of the maximum value, and the effluent ammonia nitrogen and TN are stably lower than 0.5 and 5 mg / L.

[0105] Comparative Example 1:

[0106] A municipal sewage treatment plant in northern China conducted an anaerobic ammonium oxidation pilot test with a designed water treatment capacity of 500m3. 3 / d, the designed inlet water quality is shown in Table 2, and the operation is carried out according to the following steps.

[0107] Table 2 Design of inlet and outlet water quality of a municipal sewage treatment module in the north

[0108]

[0109] S1) Equipment Construction:

[0110] The sewage treatment module includes the first reaction tank I, the second reaction tank II, the third reaction tank III, the fourth reaction tank IV, and the fifth reaction tank V, which are arranged in sequence. The effective capacity of each tank is 21m 3 The total HRT of the equipment is 5.04h. Intercepting screens S1~S5 are provided at the ends of the reaction tanks I~V, and gates N1~N4 are provided on the intercepting screens. The first reaction tank I and the fifth reaction tank V are connected by a water passage g. A first water passage gate f1 is provided on the water passage side of the first reaction tank, and a second water passage gate f2 and a third water passage gate f3 are provided on the water passage side of the front and rear ends of the screen of the fifth reaction tank respectively. The gate height is 20cm. A liftable water weir is provided behind the intercepting screen S5, and the liftable height is 15cm. A stirring device is provided in the first reaction tank I, the second reaction tank II and the fifth reaction tank V, and the stirring device of the fifth reaction tank is installed opposite to the second water passage gate. The stirring power density is 5W / m 3 A perforated aeration device is provided in the third reaction tank III to the fifth reaction tank V, and the diameter of the aeration hole is 4 mm. Suspended carriers are added to the first reaction tank I to the fifth reaction tank V, and the average pore diameter of the suspended carriers is 5 mm, and the effective specific surface area is 620 m 2 / m 3 The filling rate of each pool is 55%, and the MLSS in the equipment is <500mg / L; the DO of the third reaction pool III is controlled at 6~8mg / L, and the total nitrogen load of the first reaction pool I and the second reaction pool II is 1.2 and 0.55gN / m2 / d; the ammonia oxidation load of the third reaction tank III is 1.0gN / m 2 / d, the biofilm thickness reached 505μm, and the TN load was 0.15gN / m 2 / d; effluent ammonia nitrogen ≤ 0.5 mg / L, effluent TN ≤ 5 mg / L;

[0111] S2) Aerobic biofilm thickness enhancement:

[0112] The aeration of the third reaction tank III was reduced to 2-3 mg / L, the ammonia nitrogen loss was reduced to 8%, and the DO of the fourth reaction tank IV and the fifth reaction tank V was increased to 6-8 mg / L. The average biofilm thickness of the fourth reaction tank IV and the fifth reaction tank V were 405 μm and 333 μm, respectively, and the ammonia oxidation loads were 1.0 and 0.86 gN / m 2 / d, and the TN removal load was 0.05 gN / m 2 / d, 0.01gN / m 2 / d, during this process, the effluent ammonia nitrogen is ≤0.5 mg / L, and the effluent TN is ≤5 mg / L, and the process proceeds to step S3;

[0113] S3) Anaerobic ammonium oxidation acclimation of anoxic biofilms:

[0114] The flow rate (0.5 m / s) and reflux ratio (230%) in the first reaction tank I and the second reaction tank II were gradually increased until the average nitrous oxide concentration in the first reaction tank I and the second reaction tank II was > 0.5 mg / L for 15 consecutive days (the actual value was 0.56 mg / L). At this time, the ammonia nitrogen removal loads in the first reaction tank I and the second reaction tank II were 0.07 and 0.037 gN / m 2 / d, the dominant anaerobic ammonia-oxidizing bacteria is CB, with relative abundances of 0.9% and 0.57% respectively. In this process, the effluent ammonia nitrogen is ≤0.5 mg / L, and the effluent TN is ≤5 mg / L, and the process proceeds to step S4;

[0115] S4) Anoxic / Aerobic Carrier Migration:

[0116] The liquid level of the first reaction tank I to the fifth reaction tank V is raised by 15 cm, the intercepting screen gates N1-N4 are opened, the third water gate f3 is closed, the second water gate f2 is opened, and the stirring device is turned on. The suspended carriers flowed from the first reactor I to the second reactor II, then from the second reactor II to the third reactor III, then from the third reactor III to the fourth reactor IV, then from the fourth reactor IV to the fifth reactor V, which then flowed through the water corridor to the first reactor. After 0.3 HRT of migration, the system returned to its pre-migration state. However, because the biofilm thickness and TN removal load in the fourth and fifth reactors IV and V did not meet the requirements, TN removal in the anoxic zone decreased after the carrier migration. The ANAMMOX load provided by the anoxic carriers could not compensate for the load reduction caused by the carrier migration. Furthermore, the ANAMMOX load in the first, second, and third reactors I, II, and III increased slowly, causing the effluent ammonia nitrogen to rise above 1 mg / L and TN to reach 5-7 mg / L, failing the TN ≤ 5 requirement. The influent flow rate had to be reduced to 80% to ensure compliance. Subsequent equipment adjustments were made as required, successfully achieving mainstream ANAMMOX, with stable effluent meeting standards throughout the entire process.

[0117] It can be seen from this that before the carrier migration, the load and biofilm thickness of each pool should meet the requirements before migration is carried out to ensure that the effluent is stable and meets the standards during the migration process and that anaerobic ammonia-oxidizing bacteria are effectively enriched after the migration.

[0118] Comparative Example 2:

[0119] After the equipment in comparative example 1 was successfully started, the anaerobic ammonia oxidation loads of the third reaction tank III and the fourth reaction tank IV were 0.26 and 0.22 gN / m 2 / d, the dominant anaerobic ammonia oxidizing bacteria genus was Candidatus Brocadia, with relative abundances of 1.74% and 1.11%, respectively. After that, the equipment no longer carried out carrier migration, and the pilot equipment was sampled every three months for high-throughput measurement, a total of 3 times. The results showed that the relative abundances of anaerobic ammonia oxidizing bacteria in the third reaction tank III and the fourth reaction tank IV decreased significantly, which were 1.74%, 1.51%, 1.09%, 0.47% and 1.11%, 0.80%, 0.39%, 0.05%, respectively. At the same time, it was also accompanied by a continuous decrease in the anaerobic ammonia oxidation load, which was 0.26, 0.22, 0.15, and 0.09 gN / m 2 / d and 0.22, 0.17, 0.08, 0.03 gN / m 2 This shows that anaerobic ammonium oxidation is prone to degradation under mainstream aerobic conditions and must be maintained by continuously replenishing the seed source. It is difficult to maintain a good operating effect by simply relying on the fed-batch inoculation of biofilm shed in the anoxic zone.

[0120] 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 method for using a migratable biofilm autotrophic denitrification device, characterized in that, The following steps are included in sequence: Step 1, the equipment includes a first reaction tank, a second reaction tank, a third reaction tank, a fourth reaction tank and a fifth reaction tank which are arranged in sequence from front to back, a total water inlet pipeline is arranged at the front end of the first reaction tank, and a total water outlet pipeline is arranged at the end of the fifth reaction tank; interception screens are arranged at the ends of the first reaction tank, the second reaction tank, the third reaction tank, the fourth reaction tank and the fifth reaction tank; Stirring devices are provided in the first reaction tank and the second reaction tank, aeration devices are provided in the third reaction tank, the fourth reaction tank and the fifth reaction tank, suspended carriers are added to each reaction tank, and the TN removal loads of the first reaction tank and the second reaction tank are respectively greater than 1.0 N / m 2 / d and 0.5 gN / m 2 / d; the ammonia oxidation load of the third reaction tank is greater than 1.0 gN / m 2 / d, the TN removal load is greater than 0.1 gN / m 2 / d, and the average biofilm thickness is greater than 500 μm; Step 2: Aerobic biofilm thickness enhancement After the fourth reaction tank and the fifth reaction tank meet all the following conditions through relevant control operation, proceed to step 3; The average biofilm thickness of the fourth reaction tank is greater than 500 μm and the average biofilm thickness of the fifth reaction tank is greater than 400 μm. The ammonia oxidation load of the fourth reaction tank is greater than 1.0 gN / m 2 / d and the ammonia oxidation load of the fifth reaction tank is greater than 0.8 gN / m 2 / d; The TN removal loads of the fourth reaction tank and the fifth reaction tank are both greater than 0.1 gN / m 2 / d; Step 3: Anaerobic ammonium oxidation acclimatization of anoxic biofilm After the first reaction pool and the second reaction pool meet all the following conditions through relevant control, proceed to step 4; The average nitrous acid concentration in the first and second reaction tanks was greater than 0.5 mg / L for 15 consecutive days; The ammonia nitrogen removal load of the first reaction tank is greater than 0.1 gN / m 2 / d and the ammonia nitrogen removal load of the second reaction tank is greater than 0.05 gN / m 2 / d; The relative abundance of anaerobic ammonium oxidizing bacteria in the first reaction tank is greater than 1.0% and the relative abundance of anaerobic ammonium oxidizing bacteria in the second reaction tank is greater than 0.5%; Step 4: Anoxic / Aerobic Carrier Migration Through relevant control, the suspended carrier flows from the first reaction pool to the second reaction pool, the second reaction pool to the third reaction pool, the third reaction pool to the fourth reaction pool, the fourth reaction pool to the fifth reaction pool, and the fifth reaction pool flows to the first reaction pool through the water gallery until it completes 0.2 to 0.4 HRT migration and returns to the state before migration; Step 5: Anaerobic ammonium oxidation aerobic culture After the system runs stably and the following conditions are met at the same time, it proceeds to step 6: The average nitrous acid concentration in the first reaction tank was greater than 0.5 mg / L for 15 consecutive days; The ammonia nitrogen removal load of the first reaction tank is greater than 0.1 gN / m 2 / d, and the ammonia nitrogen removal load of the second reaction tank is greater than 0.05 gN / m 2 / d; The TN removal load of the third reaction tank is greater than 0.2 gN / m 2 / d; Step 6: Anaerobic ammonium oxidation aerobic enhancement Gradually increase the DO in the third reaction tank to 4 - 6 mg / L and operate until the TN removal load in the third reaction tank has been stable at > 0.2 gN / m 2 / d or more for 5 consecutive days. Repeat steps four to six to complete the migration of 3 HRTs; Step 7: The equipment runs stably.

2. The usage method of a migratable biofilm autotrophic denitrification equipment according to claim 1, characterized in that: In step one, a first gate is arranged on the interception screen of the first reaction pool, a second gate is arranged on the interception screen of the second reaction pool, a third gate is arranged on the interception screen of the third reaction pool, and a fourth gate is arranged on the interception screen of the fourth reaction pool. By opening the first gate, the second gate, the third gate or the fourth gate, the suspended carrier in the corresponding reaction pool can flow to the next reaction pool.

3. The usage method of a migratable biofilm autotrophic denitrification equipment according to claim 1, characterized in that: The first reaction tank and the fifth reaction tank are connected by a water passage corridor. A first water passage gate is arranged on the water passage corridor side of the first reaction tank, and a second water passage gate and a third water passage gate are respectively arranged on the front end and rear end water passage corridor sides of the interception screen of the fifth reaction tank. The stirring device in the fifth reaction tank is installed on the opposite side of the second water passage gate, and a liftable water outlet weir is arranged behind the interception screen of the fifth reaction tank.

4. The usage method of a migratable biofilm autotrophic denitrification equipment according to claim 1, characterized in that: In step 1, the aeration device is a perforated aeration device with a hole diameter of 4-6 mm; the MLSS of all reaction tanks is <500 mg / L, the average pore diameter of the suspended carrier is >5 mm, and the filling rate of the suspended carrier is 30%-67%.

5. The usage method of a migratable biofilm autotrophic denitrification device according to claim 3, characterized in that: The installation height of the stirring device in the fifth reaction tank is higher than 50% of the water depth and does not exceed the liquid surface; the lifting height of the liftable outlet weir is greater than 50% of the height of the second water gate; the aperture of the intercepting screen in each reaction tank is 50%~80% of the corresponding suspended carrier diameter.

6. The usage method of a migratable biofilm autotrophic denitrification equipment according to claim 1, characterized in that: The power density of the stirring devices in the first reaction tank and the second reaction tank is 5-15 W / m 3 ; the DO in the third reaction tank is 6-8 mg / L, and the DO in the fourth reaction tank and the fifth reaction tank are both 4-6 mg / L.

7. A method for using a migratable biofilm autotrophic denitrification equipment according to claim 1, characterized in that: In Step 2, the relevant control refers to: reducing the aeration in the third reaction tank until the ammonia nitrogen loss is less than 15%, and increasing the DO in the fourth reaction tank.

8. The usage method of a migratable biofilm autotrophic denitrification equipment according to claim 1, characterized in that: In Step 3, the relevant control refers to increasing the flow velocity and reflux ratio in the first and second reaction tanks.

9. The usage method of a migratable biofilm autotrophic denitrification equipment according to claim 3, characterized in that: In Step 4, the relevant control refers to: raising the liquid levels of the first to fifth reaction tanks, opening the first to fourth gates, closing the third water passing gate, opening the second water passing gate and starting the stirring device in the fifth reaction tank. At this time, the suspended carriers flow from the first reaction tank to the second reaction tank, from the second reaction tank to the third reaction tank, from the third reaction tank to the fourth reaction tank, from the fourth reaction tank to the fifth reaction tank, and the fifth reaction tank flows to the first reaction tank through the water passing corridor; The specific steps for the equipment to operate stably in Step 7 are as follows. When the equipment maintains stable operation every 3 months or when any one of the ammonia oxidation loads in the first and second reaction tanks or the TN removal loads in the third and fourth reaction tanks drops by more than 30%, repeat Steps 1 to 7; The ammonia nitrogen and TN in the effluent of the equipment in Steps 1 to 7 are stably less than 0.5 mg / L and 5 mg / L respectively.

10. The usage method of a migratable biofilm autotrophic denitrification equipment according to claim 1, characterized in that: In Step 2, the DO in the third reaction tank is controlled at 2 - 4 mg / L, and the DO in the fourth and fifth reaction tanks is controlled at 6 - 8 mg / L; in Step 3, the average flow rate is increased in gradients, with the increase gradient being 0.05 - 0.1 m / s, and the reflux ratio is increased in gradients, with the increase gradient being 30% - 50%, and each gradient lasts for 5 days; in Step 4, when the anoxic / aerobic carrier migrates, the liquid level in the fifth reaction tank exceeds 50% above the lowest point of the second overflow gate; in Step 5, the DO in the third reaction tank is controlled at 2 - 4 mg / L, and the aeration intensity is controlled at 4 - 6 m 3 / m 2 / h, the DO in the fourth reaction tank is controlled at 4 - 6 mg / L, and the aeration intensity > 10 m 3 / m 2 / h, the DO in the fifth reaction tank is controlled at 8 - 10 mg / L, and the aeration intensity > 12 m 3 / m 2 / h; in Step 6, maintain the TN removal load in the third reaction tank > 0.2 gN / m 2 / d, the DO in the third reaction tank is increased in gradients, with the increase gradient being 0.5 mg / L, and the DO in the fifth reaction tank is decreased to 6 - 8 mg / L at the same gradient.

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