Usage method of a transferable biofilm autotrophic denitrification equipment

Abstract

The invention discloses a usage method of a migratable biofilm autotrophic denitrification equipment, which relates to the technical field of sewage treatment. It includes steps such as equipment construction, aerobic biofilm thickness enhancement, anoxic biofilm anaerobic ammonium oxidation domestication, anoxic / aerobic carrier migration, anaerobic ammonium oxidation aerobic cultivation, anaerobic ammonium oxidation aerobic enhancement, etc. After the successful startup of the invention, the overall mainstream anaerobic ammonium oxidation load of the equipment can reach more than 0.65 gN / m<supgt;2< / supgt; / d, and the denitrification contribution rate can reach more than 50%, getting rid of the dependence on externally added carbon sources for denitrification of low carbon-nitrogen ratio sewage; at the same time, reducing the aeration energy consumption by more than 20%; the invention can realize the enrichment startup of anaerobic ammonium oxidation on the basis of the normal operation of the process, and the effluent quality during the suspended carrier migration process always maintains high standards of ammonia nitrogen <0.5 mg / L and TN < 5 mg / L, reducing the time, equipment and labor costs for the startup of anaerobic ammonium oxidation, and avoiding water quality exceeding the standard or reduced operation due to the startup of anaerobic ammonium oxidation.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and specifically relates to a method for using a relocatable biofilm autotrophic denitrification equipment. Background Art

[0002] The anaerobic ammonium oxidation process can save more than 60% of the aeration volume and 100% of the carbon source addition compared with the traditional nitrification and denitrification, achieving green and low-carbon sewage treatment. However, it is currently mainly applied to the treatment of high-ammonia-nitrogen wastewater. When applied to mainstream urban sewage treatment plants, it often faces problems such as low substrate concentration, large water quality fluctuations, and low sewage temperature, resulting in difficult enrichment of anaerobic ammonium-oxidizing bacteria, long start-up periods, and the risk of continuous degradation of anaerobic ammonium-oxidizing bacteria after successful start-up, making it difficult to achieve long-term stable operation. Therefore, realizing the anaerobic ammonium oxidation process for mainstream urban sewage treatment remains a difficult problem in the industry.

[0003] Currently, for the start-up and operation of anaerobic ammonium oxidation in mainstream municipal sewage treatment, the relevant research reports of the prior art are as follows:

[0004] CN113735264A discloses a rapid start-up method for an autotrophic denitrification process of a mud-film hybrid moving bed biofilm reactor. First, short-cut nitrification flocculent sludge is inoculated, and suspended fillers are added to form an MBBR reactor. At room temperature, the ratio of influent ammonia nitrogen concentration to nitrite nitrogen concentration is controlled, and the short-cut is maintained under a relatively high aeration volume. The anoxic time is appropriately increased to successfully enrich anaerobic ammonium-oxidizing bacteria. After starting the anaerobic ammonium oxidation reaction, the aeration volume is gradually reduced to lower the DO, and the aeration time is increased to induce short-cut nitrification and anaerobic ammonium oxidation reactions to occur simultaneously in the aeration stage by aerobic ammonia-oxidizing bacteria and AnAOB. It has the following problems: First, nitrite nitrogen needs to be artificially added to the influent and the corresponding ratio needs to be controlled, which does not really solve the problem of the source of nitrite nitrogen in the anaerobic ammonium oxidation reaction, resulting in a large consumption of chemicals and being difficult to implement in engineering; second, the system DO fluctuates up and down during the start-up process, so it is impossible to ensure that the system always has good nitrification effect, and it is difficult to ensure the stable compliance of the effluent or full water volume operation during the start-up period.

[0005] CN107253762B discloses a rapid start-up method for coupling short-cut denitrification and phosphorus removal with anaerobic ammonium oxidation. It starts short-cut nitrification by connecting an AAO reaction tank in series with an MBBR reaction tank, inoculating anaerobic ammonium oxidation suspended carriers in the anoxic tank of the AAO, and inoculating short-cut nitrification sludge in the MBBR tank, and providing nitrite matrix for anaerobic ammonium oxidation through reflux, thereby realizing autotrophic denitrification. It has the following problems: First, both short-cut nitrification and anaerobic ammonium oxidation are achieved by inoculation, which does not really solve the core bottleneck of mainstream anaerobic ammonium oxidation and is difficult to effectively implement for large-scale engineering projects; second, in some system details, the density of the suspended carrier is selected to be 0.20 - 0.25 g / cm 3, the carrier density is less than that of water, and anaerobic ammonium oxidation denitrification itself is prone to generate steam, causing the carrier to float. On the premise of a relatively small 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.

[0006] It can be seen from this that the existing technology mainly realizes anaerobic ammonium oxidation denitrification of mainstream municipal sewage through methods such as adding a dosing mechanism and inoculating a matured seed source, and has not really broken through the bottleneck problem of mainstream anaerobic ammonium oxidation. It is difficult to achieve stable retention of bacteria during actual operation. Therefore, the existing technology needs to be further improved. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for using a relocatable biofilm autotrophic denitrification equipment, which can achieve the enrichment start-up of anaerobic ammonium oxidation on the basis of normal process operation. After successful start-up, the overall mainstream anaerobic ammonium oxidation load of the equipment can reach more than 0.65 gN / m 2 / d or more, and the denitrification contribution rate can reach more than 50%, getting rid of the dependence on externally added carbon sources for denitrification of low carbon-nitrogen ratio sewage; at the same time, reducing the aeration energy consumption by more than 20%.

[0008] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A method for using a relocatable biofilm autotrophic denitrification equipment successively includes the following steps:

[0010] 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 inlet water pipeline is provided at the front end of the first reaction tank, and a total outlet water pipeline is provided at the end of the fifth reaction tank; intercepting 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;

[0011] 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, and suspended carriers are added to each reaction tank. 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;

[0012] Step 2, aerobic biofilm thickness enhancement

[0013] After the fourth reaction tank and the fifth reaction tank meet all the following conditions through relevant control operations, then enter Step 3;

[0014] 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;

[0015] The TN removal loads of the fourth reaction tank and the fifth reaction tank are both greater than 0.1 gN / m 2 / d;

[0016] Step 3. Anaerobic ammonium oxidation domestication of anoxic biofilm

[0017] After the first reaction tank and the second reaction tank meet all the following conditions through relevant controls, then enter Step 4;

[0018] The average value of the nitrous oxide concentration in the first reaction tank and the second reaction tank is greater than 0.5 mg / L for 15 consecutive days;

[0019] 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;

[0020] 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%;

[0021] Step 4. Anoxic / aerobic carrier migration

[0022] Through relevant controls, 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 passage until after 0.2 - 0.4 HRT migrations, it returns to the state before migration;

[0023] Step 5. Aerobic cultivation of anaerobic ammonium oxidation

[0024] After stable operation to simultaneously meet the following conditions, then enter Step 6:

[0025] The average value of the nitrous oxide concentration in the first reaction tank is greater than 0.5 mg / L for 15 consecutive days;

[0026] 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 0.05 gN / m 2 / d;

[0027] The TN removal load of the third reaction tank is greater than 0.2 gN / m 2 / d;

[0028] Step 6: Anaerobic ammonia oxidation aerobic enhancement

[0029] Gradually increase the DO in the third reaction tank to 4 - 6 mg / L and operate until the load of the third reaction tank has been stable at > 0.2 gN / m 2 / d or more for 5 consecutive days. Repeat Steps 4 to 6 to complete the migration of 3 HRTs;

[0030] Step 7: Equipment stable operation.

[0031] For the usage method of the above-mentioned migratable biofilm autotrophic denitrification equipment, in Step 1, a first gate is provided on the interception screen of the first reaction tank, a second gate is provided on the interception screen of the second reaction tank, a third gate is provided on the interception screen of the third reaction tank, and a fourth gate is provided 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 carriers in the corresponding reaction tank can flow into the next reaction tank.

[0032] For the usage method of the above-mentioned migratable biofilm autotrophic denitrification equipment, the first reaction tank and the fifth reaction tank are connected through a water passage corridor. A first water passage gate is provided on the side of the water passage corridor of the first reaction tank, a second water passage gate and a third water passage gate are respectively provided on the front and rear sides of the water passage corridor 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 effluent weir is provided behind the interception screen of the fifth reaction tank.

[0033] For the usage method of the above-mentioned migratable biofilm autotrophic denitrification equipment, in Step 1, the aeration device is perforated aeration, and the hole diameter is 4 - 6 mm; the MLSS of the suspended carrier < 500 mg / L, the average void diameter of the suspended carrier > 5 mm, and the filling rate of the suspended carrier is 30% - 67%.

[0034] For the usage method of the above-mentioned migratable biofilm autotrophic denitrification equipment, 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 level; the lifting height of the liftable effluent weir should be greater than 50% of the height of the second water passage gate; the aperture of the interception screen in each reaction tank is 50% - 80% of the diameter of the corresponding suspended carrier.

[0035] For the usage method of the above-mentioned migratable biofilm autotrophic denitrification equipment, the power density of the stirring devices in the first reaction tank and the second reaction tank is 5 - 15 W / m 3The DO in the third reaction tank is 6 - 8 mg / L, and the DO in the fourth and fifth reaction tanks is 4 - 6 mg / L.

[0036] In the method for using the above-mentioned relocatable biofilm autotrophic denitrification equipment, in step two, the relevant control means: 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; in step three, the relevant control through means increasing the flow velocity and reflux ratio in the first and second reaction tanks.

[0037] In the method for using the above-mentioned relocatable biofilm autotrophic denitrification equipment, in step four, the relevant control through means: 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 of 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 stable operation of the equipment in step seven are that 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 one to seven; the ammonia nitrogen and TN in the effluent of the equipment in steps one to seven are stably less than 0.5 mg / L and 5 mg / L respectively.

[0038] In the method for using the above-mentioned relocatable biofilm autotrophic denitrification equipment, in step two, 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 three, the average flow velocity 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 four, when the anoxic / aerobic carrier migrates, the liquid level in the fifth reaction tank exceeds 50% above the lowest point of the second water passing gate; in step five, 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 six, keep 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.

[0039] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0040] 1) Energy conservation and consumption reduction. After the successful startup of the present invention, the overall mainstream anaerobic ammonium oxidation load of the equipment can reach more than 0.65 gN / m 2 / d, and the denitrification contribution rate can reach more than 50%, getting rid of the dependence on externally added carbon sources for denitrification of low-carbon-nitrogen ratio sewage; at the same time, the aeration energy consumption is reduced by more than 20%;

[0041] 2) High standards. The method of the present invention can realize the enrichment startup of anaerobic ammonium oxidation on the basis of normal operation. The water quality of the effluent during the migration process of the suspended carriers always maintains high standards of ammonia nitrogen <0.5 mg / L and TN < 5 mg / L, reducing the startup time, equipment and labor costs of anaerobic ammonium oxidation, and avoiding water quality exceeding the standard or reduced operation caused by the startup of anaerobic ammonium oxidation;

[0042] 3) Strong stability. The present invention provides a method for maintaining the anaerobic ammonium oxidation effect of the equipment for a long time. After successful startup, the maintenance rate of the anaerobic ammonium oxidation load can be stably above 70%, and the lowest applicable temperature can reach 10°C, overcoming the problem of difficult stable operation of the anaerobic ammonium oxidation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will be further described below with reference to the accompanying drawings:

[0044] Figure 1 It is a schematic structural diagram of the equipment of the present invention;

[0045] Figure 2 It is the load and relative abundance change of anaerobic ammonium oxidizing bacteria in the third reaction tank III and the fourth reaction tank IV of Comparative Example 2;

[0046] In the figure: I, the first reaction tank, II, the second reaction tank, III, the third reaction tank, IV, the fourth reaction tank, V, the fifth reaction tank, I1, the total inlet pipeline, I2, the total outlet pipeline, S1, the intercepting screen of the first reaction tank, S2, the intercepting screen of the second reaction tank, S3, the intercepting screen of the third reaction tank, S4, the intercepting screen of the fourth reaction tank, S5, the intercepting screen of the fifth reaction tank, N1, the first gate, N2, the second gate, N3, the third gate, N4, the fourth gate, f1, the first water passing gate, f2, the second water passing gate, f3, the third water passing gate, J, the stirring device, g, the water passing corridor, Y, the liftable effluent weir. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application.

[0048] In the description of this application, terms such as "first" and "second" are only used to distinguish different objects, and do not limit the quantity and execution order. Moreover, terms such as "first" and "second" do not necessarily mean different. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0049] Regarding the structures and operating principles of the stirring device and aeration device described in the present invention, those skilled in the art can refer to the prior art to implement them.

[0050] The following further describes the technical solutions of this application in detail with reference to the accompanying drawings.

[0051] The following explanations are made for the proprietary terms involved in the present invention:

[0052] Ammonia nitrogen removal load: the amount of ammonia nitrogen removed by the biofilm per unit area per unit time, gN / m 2 / d;

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

[0054] HRT: hydraulic retention time, the average residence time of the sewage to be treated in the reaction tank, h;

[0055] Relative abundance of anaerobic ammonium oxidation bacteria: the ratio of the number of anaerobic ammonium oxidation bacteria to the total number of bacteria in the flora, %;

[0056] DO: dissolved oxygen, molecular oxygen dissolved in water, mg / L.

[0057] The following further describes the technical solutions of this application in detail with reference to the accompanying drawings.

[0058] As Figure 1As shown in the figure, 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. A main inlet pipeline I1 is provided at the front end of the first reaction tank, and a main outlet pipeline I2 is provided at the end of the fifth reaction tank; Intercepting 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 intercepting screen S1 of the first reaction tank, the intercepting screen S2 of the second reaction tank, the intercepting screen S3 of the third reaction tank, the intercepting screen S4 of the fourth reaction tank, and the intercepting screen S5 of the fifth reaction tank; A first gate N1 is provided on the intercepting screen S1 of the first reaction tank, a second gate N2 is provided on the intercepting screen S2 of the second reaction tank, a third gate N3 is provided on the intercepting screen S3 of the third reaction tank, and 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 passage g. A first water passage gate f1 is provided on the side of the water passage of the first reaction tank, and a second water passage gate f2 and a third water passage gate f3 are respectively provided on the front and rear sides of the water passage of the screen of the fifth reaction tank. Stirring devices J 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. A liftable effluent weir Y is provided behind the intercepting screen of the fifth reaction tank. Suspended carriers are added to each reaction tank, MLSS < 500mg / L, the average pore diameter of the suspended carriers > 5mm, and the TN removal loads of the first reaction tank and the second reaction tank are respectively greater than 1.0N / m 2 / d, 0.5gN / m 2 / d, and the ammonia oxidation load of the third reaction tank is greater than 1.0gN / m 2 / d, and the TN removal load is greater than 0.1gN / m 2 / d.

[0059] Combined with the above equipment, the denitrification method of the present invention will be described in detail.

[0060] The denitrification method of the present invention mainly includes: ① Equipment construction to ensure stable compliance of the effluent, complete the biofilm formation in the third reaction tank, and provide conditions for the biofilm formation in the fourth and fifth reaction tanks; ② Enhancement of aerobic biofilm thickness, conduct enhanced biofilm formation in the fourth and fifth reaction tanks, enrich internal denitrifying bacteria based on the biofilm thickness, ensure the anoxic denitrification effect after the carrier migration, and lay a foundation for the enrichment of anaerobic ammonium oxidation; ③ Anoxic biofilm anaerobic ammonium oxidation domestication, first achieve the enrichment of anaerobic ammonium oxidizing bacteria in the anoxic zone, and provide a basis for the subsequent carrier migration; ④ Anoxic / aerobic carrier migration, inoculate and start aerobic anaerobic ammonium oxidation after anoxic enrichment of anaerobic ammonium oxidation; ⑤ Anaerobic ammonium oxidation aerobic cultivation, conduct low-DO anaerobic ammonium oxidation cultivation in the third reaction tank to prevent high-DO inhibition, and at the same time ensure the nitrification effect in the fifth reaction tank; ⑥ Anaerobic ammonium oxidation aerobic enhancement, gradually increase the DO in the third reaction tank to enhance the DO tolerance of aerobic anaerobic ammonium oxidation, and provide a basis for further migration to the fourth reaction tank with high DO; ⑦ Stable operation of the equipment, ensure that the anaerobic ammonium oxidation effect in the equipment always remains above 70% of the highest value by regularly repeating the above steps.

[0061] The specific steps are as follows:

[0062] Step 1: Construct the above equipment;

[0063] Step 2: Enhancement of aerobic biofilm thickness

[0064] Reduce the aeration in the third reaction tank until the ammonia nitrogen loss is less than 15%, increase the DO in the fourth reaction tank, and when the fourth and fifth reaction tanks meet all the following conditions, then enter Step 3;

[0065] 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;

[0066] The TN removal loads of the fourth and fifth reaction tanks are both greater than 0.1 gN / m 2 / d;

[0067] Step 3: Anoxic biofilm anaerobic ammonium oxidation domestication

[0068] Increase the flow rate and reflux ratio in the first and second reaction tanks, and when the first and second reaction tanks meet all the following conditions, then enter Step 4;

[0069] The average concentration of nitrite nitrogen in the first and second reaction tanks is greater than 0.5 mg / L for 15 consecutive days;

[0070] 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;

[0071] 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%;

[0072] Step 4. Anoxic / aerobic carrier migration

[0073] Raise the liquid levels of the first to fifth reaction tanks, open the first to fourth gates, close the third water passing gate, open the second water passing gate and the stirring device. 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 until it returns to the state before migration after 0.2 - 0.4 HRT migrations;

[0074] Step 5. Anaerobic ammonium-oxidizing aerobic cultivation

[0075] After stable operation to simultaneously meet the following conditions, then enter Step 6:

[0076] The average value of the nitrous nitrogen concentration in the first reaction tank is greater than 0.5 mg / L for 15 consecutive days;

[0077] 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 0.05 gN / m 2 / d;

[0078] The TN removal load of the third reaction tank is greater than 0.2 gN / m 2 / d;

[0079] Step 6. Anaerobic ammonium-oxidizing aerobic strengthening

[0080] 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 2 / d for 5 consecutive days. Repeat Steps 4 to 6 to complete 3 HRT migrations;

[0081] Step 7. When the equipment maintains stable operation every 3 months or when any one 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%, 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.

[0082] Preferably, in step one, the aeration device is perforated aeration, and the aperture diameter of the perforation is 4 - 6 mm.

[0083] Preferably, the installation height of the stirring device is higher than 50% of the water depth and does not exceed the liquid level; the lifting height of the liftable effluent weir should be greater than 50% of the height of the second water passing gate; the aperture of the intercepting screen in each reaction tank is 50% - 80% of the diameter of the corresponding suspended carrier.

[0084] Preferably, 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 of the third reaction tank is 6 - 8 mg / L, and the DO of the fourth reaction tank and the fifth reaction tank are both 4 - 6 mg / L.

[0085] Preferably, in step two, 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 are controlled at 6 - 8 mg / L; in step three, the average flow velocity is increased in gradients, the increasing gradient is 0.05 - 0.1 m / s, the reflux ratio is increased in gradients, the increasing gradient is 30% - 50%, and the duration of each gradient is 5 days; in step four, when the anoxic / aerobic carrier migrates, the liquid level of the fifth reaction tank exceeds 50% above the lowest point of the second water passing gate; in step five, the DO of the third reaction tank is controlled at 2 - 4 mg / L, the aeration intensity is controlled at 4 - 6 m 3 / m 2 / h, the DO of the fourth reaction tank is controlled at 4 - 6 mg / L, and the aeration intensity > 10 m 3 / m 2 / h, the DO of the fifth reaction tank is controlled at 8 - 10 mg / L, and the aeration intensity > 12 m 3 / m 2 / h; in step six, keep the TN removal load of the third reaction tank > 0.2 gN / m 2 / d, the DO of the third reaction tank is increased in gradients, the increasing gradient is 0.5 mg / L, and the DO of the fifth reaction tank is decreased to 6 - 8 mg / L at the same gradient.

[0086] The following further describes the present invention in detail with specific embodiments.

[0087] Example 1:

[0088] A municipal sewage treatment module is designed to treat a water volume of 1.0×10 4 m 3 / d, and the designed influent water quality is shown in Table 1 and operates according to the following steps.

[0089] Table 1 Designed influent and effluent water quality of a municipal sewage treatment module

[0090] Index <![CDATA[COD Cr > <![CDATA[BOD 5 > SS (mg / L) TN <![CDATA[NH 3 -N]]> TP Design influent 500 200 450 70 50 8 Design effluent 40 10 10 5 1.5(3) 0.4

[0091] S1) Equipment construction:

[0092] The sewage treatment module 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. The effective volume of each tank is 625 m 3 , the total HRT of the equipment is 7.5 h. Intercepting screens are set at the ends of each reaction tank. Gates are set on the intercepting screens from the first reaction tank to the fourth reaction tank. The first reaction tank and the fifth reaction tank are connected by a water passage corridor. A first water gate is set on the side of the water passage corridor of the first reaction tank. A second water gate and a third water gate are respectively set on the front and rear sides of the water passage corridor of the fifth reaction tank in front of and behind the screen. The height of the gate is 50 cm. A stirrer is installed opposite to the second water gate. A liftable effluent weir is set behind the intercepting screen of the fifth reaction tank, and the liftable height is 30 cm. Stirring devices are set in the first reaction tank and the second reaction tank, and the stirring power density is 7.5 W / m 3 , perforated aeration devices are set in the third, fourth, and fifth reaction tanks, and the diameter of the aeration holes is 4 mm. Suspended carriers are added to each reaction tank. The average void diameter of the suspended carriers is 5 mm, and the effective specific surface area is 620 m 2 / m 3 , the filling rate is 55% for all, and the MLSS in the equipment < 500 mg / L; the DO in the third reaction tank is controlled at 6 - 8 mg / L. When operating, the TN removal loads of the first and second reaction tanks are 1.2 and 0.55 gN / m 2 / d respectively; the ammonia oxidation load of the third reaction tank III is 1.3 gN / m 2 / d, the biological membrane thickness reaches 510 μm, and the TN removal load is 0.15 gN / m 2 / d; the effluent ammonia nitrogen ≤ 0.5 mg / L, and the effluent TN ≤ 5 mg / L;

[0093] S2) Enhancement of aerobic biological membrane thickness:

[0094] Reduce the DO in the third reaction tank to 2 - 4 mg / L, reduce the ammonia nitrogen loss to 10%, increase the DO in the fourth and fifth reaction tanks to 6 - 8 mg / L. The average biological membrane thickness of the fourth and fifth reaction tanks is increased to 525 μm and 433 μm respectively. The ammonia oxidation loads are 1.3 and 0.91 gN / m 2 / d respectively, and the TN removal loads are 0.15 gN / m 2 / d and 0.11 gN / m 2 / d respectively. During this process, the effluent ammonia nitrogen ≤ 0.5 mg / L, and the effluent TN ≤ 5 mg / L, then enter step S3;

[0095] S3) Anoxic biological membrane anaerobic ammonium oxidation domestication:

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

[0097] S4) Anoxic / aerobic carrier migration:

[0098] Raise the liquid level of each reaction tank by 30 cm, open the intercepting screen gate, close the third water passing gate, open the second water passing gate, and turn on the stirrer of the fifth reaction tank. Make the suspended carriers in each tank flow to the next tank in turn; after 0.4 HRT migration, restore to the state before migration; during this process, the ammonia nitrogen in the effluent ≤ 0.5 mg / L, and the TN in the effluent ≤ 5 mg / L, then enter step S5;

[0099] S5) Anaerobic ammonium-oxidation aerobic cultivation:

[0100] Maintain stable operation until the average value of nitrite nitrogen concentration in the first reaction tank is > 0.5 mg / L for 15 consecutive days (the actual value is 0.55 mg / L). At this time, the ammonia nitrogen removal loads of the first and second reaction tanks are 0.16 and 0.09 gN / m 2 / d respectively, and the TN removal load of the third reaction tank is 0.25 gN / m 2 / d. During this process, the ammonia nitrogen in the effluent ≤ 0.5 mg / L, and the TN in the effluent ≤ 5 mg / L, then enter step S6;

[0101] S6) Anaerobic ammonium-oxidation aerobic strengthening:

[0102] Gradually increase the DO in the third reaction tank to 4 - 6 mg / L and operate until the TN removal load of the third reaction tank is stably > 0.2 gN / m 2 / d for 5 consecutive days (the actual value is 0.22 - 0.26 gN / m 2 / d). Repeat steps S4 - 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 2 / d respectively, and the TN removal loads of the third and fourth reaction tanks are 0.27 and 0.21 gN / m 2 / d. When the ammonia oxidation load of the first reaction tank, the second reaction tank, or the TN removal load of the third reaction tank and the fourth reaction tank decreases by more than 30% every 3 months or at the first response, repeat steps S1 - S7 to maintain the load stability. The equipment has been stably operated for more than two years, and the maximum anaerobic ammonia oxidation load reaches 0.86 gN / m 2 / d or more, the aeration energy consumption is reduced by more than 30%. Under the condition that the water temperature reaches 8.5 °C in winter, the anaerobic ammonia oxidation load still ensures 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 respectively.

[0105] Comparative Example 1:

[0106] A pilot-scale anaerobic ammonia oxidation test was carried out in a municipal sewage treatment plant in the north. The designed treatment capacity is 500 m 3 / d. The designed influent water quality is shown in Table 2 and it is operated according to the following steps.

[0107] Table 2 Designed influent and effluent water quality of a municipal sewage treatment module in the north

[0108] Index <![CDATA[COD Cr > <![CDATA[BOD 5 > SS (mg / L) TN <![CDATA[NH 3 -N]]> TP Design influent 550 230 400 65 40 9 Design effluent 40 10 10 5 1.5(3) 0.4

[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 arranged in sequence. The effective volume of each tank is 21 m 3 , the total HRT of the equipment is 5.04 h. Intercepting screens S1 - S5 are set at the ends of reaction tanks I - V, and gates N1 - N4 are set on the intercepting screens. The first reaction tank I and the fifth reaction tank V are connected by a water passage corridor g. A first water passage gate f1 is set on the side of the water passage corridor of the first reaction tank. Second water passage gate f2 and third water passage gate f3 are set on the side of the water passage corridor at the front and back of the screen of the fifth reaction tank respectively. The height of the gates is 20 cm. A liftable effluent weir is set behind the intercepting screen S5, and the liftable height is 15 cm. Stirring devices are set 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, and the stirring power density is 5 W / m 3 , perforated aeration devices are set in the third reaction tank III - the fifth reaction tank V, and the diameter of the aeration holes is 4 mm. Suspended carriers are added to the first reaction tank I - the fifth reaction tank V. The average void 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 tank is 55%, and the MLSS in the equipment is < 500 mg / L; the DO in the third reaction tank II is controlled at 6 - 8 mg / L. When it runs until the total nitrogen loads of the first reaction tank I and the second reaction tank II are 1.2 and 0.55 gN / m2 / d; The ammonia oxidation load of the third reaction tank III is 1.0 gN / m 2 / d, the biofilm thickness reaches 505 μm, and the TN load is 0.15 gN / m 2 / d; The effluent ammonia nitrogen ≤ 0.5 mg / L, and the effluent TN ≤ 5 mg / L;

[0111] S2) Enhancement of aerobic biofilm thickness:

[0112] Reduce the aeration in the third reaction tank III to 2 - 3 mg / L, reduce the ammonia nitrogen loss to 8%, increase the DO in the fourth reaction tank IV and the fifth reaction tank V to 6 - 8 mg / L, and operate until the average biofilm thicknesses of the fourth reaction tank IV and the fifth reaction tank V are 405 μm and 333 μm respectively, and the ammonia oxidation loads are 1.0 and 0.86 gN / m 2 / d, and the TN removal loads are 0.05 gN / m 2 / d, 0.01 gN / m 2 / d. During this process, the effluent ammonia nitrogen ≤ 0.5 mg / L, and the effluent TN ≤ 5 mg / L, then enter step S3;

[0113] S3) Anaerobic ammonium oxidation domestication of anoxic biofilm:

[0114] Gradually increase the flow rate (0.5 m / s) and the reflux ratio (230%) in the first reaction tank I and the second reaction tank II until the average value of the nitrite nitrogen concentration in the first reaction tank I and the second reaction tank II > 0.5 mg / L for 15 consecutive days (the actual value is 0.56 mg / L). At this time, the ammonia nitrogen removal loads of the first reaction tank I and the second reaction tank II are 0.07 and 0.037 gN / m 2 / d respectively, the dominant anaerobic ammonium oxidation bacteria are CB, and the relative abundances are 0.9% and 0.57% respectively. During this process, the effluent ammonia nitrogen ≤ 0.5 mg / L, and the effluent TN ≤ 5 mg / L, then enter step S4;

[0115] S4) Anoxic / aerobic carrier migration:

[0116] The liquid levels of the first reaction tank I to the fifth reaction tank V are raised by 15 cm, the intercepting screen gate N1 - N4 is opened, the third water passing gate f3 is closed, the second water passing gate f2 is opened, and the stirring device is started. The suspended carriers flow from the first reaction tank I to the second reaction tank II, from the second reaction tank II to the third reaction tank III, from the third reaction tank III to the fourth reaction tank IV, from the fourth reaction tank IV to the fifth reaction tank V, and the fifth reaction tank V flows to tank I through the water passing corridor; after 0.3 HRT migration, it returns to the state before migration; due to the fact that the biofilm thickness and TN removal load in the fourth reaction tank IV and the fifth reaction tank V do not meet the requirements, resulting in a decrease in TN removal in the anoxic zone after carrier migration, and the anaerobic ammonium oxidation load provided by the anoxic carriers cannot compensate for the load reduction caused by carrier migration, and the anaerobic ammonium oxidation load in the first reaction tank I, the second reaction tank II and the third reaction tank III increases slowly, resulting in the effluent ammonia nitrogen rising above 1 mg / L and TN reaching 5 - 7 mg / L, not meeting the requirement of TN ≤ 5, so the influent water volume can only be reduced to 80% for operation to ensure compliance. The subsequent equipment was adjusted according to the requirements, and the mainstream anaerobic ammonium oxidation effect was successfully achieved, and the effluent was stably compliant throughout the process.

[0117] Thus, before carrier migration, the loads of each tank and the biofilm thickness should meet the requirements before migration to ensure the stable compliance of the effluent during migration and the effective enrichment of anaerobic ammonium oxidizing bacteria after migration.

[0118] Comparative Example 2:

[0119] After the equipment in Comparative Example 1 was successfully started, the anaerobic ammonium oxidation loads of the third reaction tank III and the fourth reaction tank IV were 0.26 and 0.22 gN / m 2 / d respectively, and the dominant anaerobic ammonium 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-scale equipment was sampled every three months for high-throughput determination, a total of 3 times. The results showed that the relative abundances of anaerobic ammonium oxidizing bacteria in the third reaction tank III and the fourth reaction tank IV both decreased significantly, to 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 ammonium oxidation load, with loads of 0.26, 0.22, 0.15, 0.09 gN / m 2 / d and 0.22, 0.17, 0.08, 0.03 gN / m 2 / d respectively. Thus, it can be seen that anaerobic ammonium oxidation is prone to degradation under mainstream aerobic conditions and must be maintained by continuously supplementing the seed source. It is difficult to maintain good operation effects simply relying on the addition and inoculation of the shed biofilm in the anoxic zone.

[0120] Those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present application, rather than to limit the present application. As long as within the scope of the essential spirit of the present application, appropriate changes and variations made to the above embodiments fall within the scope claimed by the present application.

Claims

1. Method for using a migratable biofilm autotrophic denitrification equipment, Characterized in that, It successively includes the following steps: 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 inlet water pipeline is arranged at the front end of the first reaction tank, and a total outlet water pipeline is arranged at the end of the fifth reaction tank; Intercepting 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 1.0N / m 2 / d and 0.5gN / m 2 / d; the ammonia oxidation load of the third reaction tank is greater than 1.0gN / m 2 / d, the TN removal load is greater than 0.1gN / m 2 / d, and the average biofilm thickness is greater than 500μm; Step 2: Enhancement of aerobic biofilm thickness After the fourth reaction tank and the fifth reaction tank meet all the following conditions through relevant control operations, then enter 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 domestication of anoxic biofilm After the first reaction tank and the second reaction tank meet all the following conditions through relevant control, then enter Step 4; The average value of nitrite nitrogen concentration in the first reaction tank and the second reaction tank is 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 oxidation bacteria in the first reaction tank is greater than 1.0% and the relative abundance of anaerobic ammonium oxidation bacteria in the second reaction tank is greater than 0.5%; Step 4: Anoxic / aerobic carrier migration Through relevant control, 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 a water passage corridor until after 0.2 - 0.4 HRT migrations, it returns to the state before migration; Step 5: Aerobic cultivation of anaerobic ammonium oxidation After stable operation to simultaneously meet the following conditions, then enter Step 6: The average value of nitrite nitrogen concentration in the first reaction tank is 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: Aerobic enhancement of anaerobic ammonium oxidation 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: Stable operation of the equipment.

2. The method for using a migratable biofilm autotrophic denitrification equipment according to claim 1, Characterized in that: In Step 1, a first gate is arranged on the intercepting screen of the first reaction tank, a second gate is arranged on the intercepting screen of the second reaction tank, a third gate is arranged on the intercepting screen of the third reaction tank, and a fourth gate is arranged on the intercepting screen of the fourth reaction tank. By opening the first gate, the second gate, the third gate or the fourth gate, the suspended carriers in the corresponding reaction tank can flow into the next reaction tank.

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

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

5. The usage method of a migratable biofilm autotrophic denitrification equipment 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 level; the lifting height of the liftable effluent weir is greater than 50% of the height of the second water passing gate; the aperture of the intercepting screen in each reaction tank is 50% - 80% of the diameter of the corresponding suspended carrier.

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. The usage method of a migratable biofilm autotrophic denitrification equipment according to claim 1, characterized in that: In Step 2, the relevant control means: 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 means 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 means: 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 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, 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 passing corridor; the specific steps for the stable operation of the equipment in Step 7 are that 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 carriers migrate, 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.

Images