A method and apparatus for denitrification treatment

Abstract

This invention provides a method and apparatus for denitrification, relating to the field of wastewater treatment technology. The denitrification apparatus provided by this invention has a reactor 13 divided into an aeration zone and an anoxic zone from top to bottom. In the anoxic zone, wastewater containing ammonia nitrogen utilizes its own COD to convert nitrate nitrogen into nitrite nitrogen, achieving short-cut denitrification. Aeration is supplied to the aeration zone via a membrane module 4, enabling a synergistic reaction of ammonia oxidation and anaerobic ammonia oxidation. Ammonia oxidation converts some ammonia nitrogen into nitrite nitrogen, while anaerobic ammonia oxidation converts the remaining ammonia nitrogen and nitrite nitrogen into nitrogen gas and nitrate nitrogen. The resulting nitrate nitrogen is returned to the anoxic zone via a liquid return path 9, forming a nitrogen cycle. This achieves partitioned coupling of short-cut denitrification and ammonia oxidation-anaerobic ammonia oxidation within the same reactor, eliminating the need for multi-stage equipment series connection, reducing equipment costs, and enabling stable operation of the entire apparatus after a successful initial start-up, with a short start-up cycle.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and specifically to a method and apparatus for denitrification treatment. Background Technology

[0002] With the acceleration of industrialization and the increase in urbanization, nitrogen pollution has become increasingly serious. Industrial wastewater contains large amounts of nitrogen compounds such as ammonia nitrogen, nitrate, and nitrite, and is generally characterized by high organic matter concentration, high ammonia nitrogen load, low C / N ratio, and poor biodegradability. Currently, nitrogen removal treatment for this type of wastewater still relies on traditional nitrification-denitrification biological processes, such as A / O (anaerobic-aerobic process), A... 2 / O (anaerobic-anoxic-aerobic process) and other improved processes. Although the above processes can achieve denitrification to a certain extent, they require an external carbon source, have low oxygen utilization, and high energy consumption for aeration.

[0003] Anammox is an autotrophic nitrogen removal method that can efficiently remove ammonia nitrogen in anoxic environments. This technology utilizes anammox bacteria to directly convert ammonia nitrogen into nitrogen gas using ammonia nitrogen as an electron donor and nitrite as an electron acceptor under anoxic conditions, requiring no oxygen or organic carbon source, thus significantly reducing energy consumption and treatment costs. Existing technology discloses a continuous-flow, large-circulation anammox process reactor, which connects a PDA (short-cut denitrification) reactor, an aeration tank, and a PNA (ammonia oxidation / anammox) reactor in series, forming a continuous-flow, large-circulation system. This combines short-cut denitrification / anammox with short-cut nitrification / anammox within the same system, fully leveraging the advantages of anammox technology with high nitrogen removal efficiency and low aeration energy consumption. However, the above process requires multiple stages of connected devices, resulting in high equipment costs; and in practical use, each device needs to be started sequentially until stable operation, leading to a long start-up cycle. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method and apparatus for denitrification. The apparatus provided by this invention enables short-cut denitrification and ammonia oxidation-anaerobic ammonia oxidation to be carried out in separate sections within the same reactor, eliminating the need for multi-stage series connection, resulting in low equipment cost and short start-up period.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a denitrification device, comprising: The reactor 13 has a cavity divided into an aeration zone and an anoxic zone from top to bottom. The bottom of the reactor 13 is provided with an inlet 1 that connects to the anoxic zone, and the top of the reactor 13 is provided with an outlet 11 that connects to the aeration zone. Membrane module 4, which is disposed in the aeration zone and is capable of supplying oxygen to the aeration zone without bubbles; Liquid reflux path 9 is located outside the reactor 13 and connects the oxygenation zone and the oxygen-deficient zone.

[0006] Preferably, the membrane module 4 comprises a membrane bundle formed by a plurality of hollow membrane filaments; the hollow membrane filaments are made of polyvinylidene fluoride; The pore size of a single hollow membrane filament is 0.05~0.2μm, and the effective membrane specific surface area per unit volume is 2000~5000m². 2 / m 3 .

[0007] Preferably, the denitrification device further includes: Gas stirring assembly 2, wherein the gas stirring assembly 2 is disposed at the bottom of the oxygen-deficient zone; Gas compression assembly 6, which is connected to membrane assembly 4; Alkali replenishment device 12, which is connected to the oxygen-deficient zone.

[0008] Preferably, the denitrification device further includes: Dissolved oxygen detection component 7 and pH value detection component 8; The first pump 14 is located on the passage connecting the alkali replenishment device 12 and the anoxic zone. The second pump 15 is installed on the sewage inlet passage; Exhaust port 10 is located at the top of reactor 13.

[0009] Preferably, the gas stirring assembly 2 is connected to the membrane assembly 4.

[0010] The present invention also provides a method for denitrification treatment using the denitrification device described above, including a start-up phase and an operation phase; The start-up phase includes: inoculating the anoxic zone of the reactor 13 with sludge 3 containing short-cut denitrifying bacteria and anaerobic ammonia oxidizing bacteria; transporting the first ammonia nitrogen-containing wastewater to the anoxic zone of the reactor 13 through the inlet 1 to carry out the first short-cut denitrification reaction to obtain the first nitrite nitrogen-containing wastewater; the dissolved oxygen concentration in the anoxic zone is <0.2 mg / L; The first wastewater containing nitrite nitrogen is introduced into the aeration zone, where it is supplied with oxygen through the membrane module 4 using bubble-free aeration. This allows anaerobic ammonia-oxidizing bacteria and ammonia-oxidizing bacteria to grow on the membrane module 4, and the first wastewater containing nitrite nitrogen undergoes a first ammonia oxidation-anaerobic ammonia oxidation reaction to obtain the first denitrified purified water. The dissolved oxygen concentration in the aeration zone is 0.2~0.4 mg / L. The denitrification unit is considered to have started successfully when the total nitrogen removal rate in the denitrification unit is ≥80% and it has been running stably for ≥7 days. The operation phase includes: after successful startup, the second ammonia nitrogen-containing wastewater is transported through inlet 1 to the anoxic zone of reactor 13 for a second short-range denitrification reaction to obtain the second nitrite nitrogen-containing wastewater; the second nitrite nitrogen-containing wastewater enters the aeration zone for a second ammonia oxidation-anaerobic ammonia oxidation reaction to obtain the second denitrified purified water.

[0011] Preferably, during the start-up phase, the biomass in sludge 3 is 3000~5000 mg / L; the filling rate of sludge 3 in reactor 13 is 30~50%.

[0012] Preferably, the start-up phase further includes adding a biological carrier 18 to the hypoxic zone; The biological carrier 18 has a filling rate of 30-50% in the hypoxic zone.

[0013] Preferably, the ammonia nitrogen concentration of the first ammonia nitrogen-containing wastewater and the second ammonia nitrogen-containing wastewater are independently 100~1500 mg / L, the total nitrogen concentration is independently 200~2000 mg / L, and the COD is independently 50~300 mg / L; The second denitrification purified water has an ammonia nitrogen concentration of <5 mg / L, a total nitrogen concentration of <10 mg / L, and a COD of <50 mg / L.

[0014] Preferably, the pH values ​​of the first short-cut denitrification reaction and the second short-cut denitrification reaction are independently 7-8; the pH values ​​of the first ammonia oxidation-anaerobic ammonia oxidation reaction and the second ammonia oxidation-anaerobic ammonia oxidation reaction are independently 7.5-8.5.

[0015] The denitrification device provided by this invention has a reactor 13 with an aeration zone and an anoxic zone divided into sections from top to bottom. In the anoxic zone, wastewater containing ammonia nitrogen utilizes its own COD to convert nitrate nitrogen into nitrite nitrogen, achieving short-cut denitrification. In the aeration zone, the membrane module 4 provides bubble-free aeration, enabling a synergistic reaction of ammonia oxidation and anaerobic ammonia oxidation. Ammonia oxidation converts some ammonia nitrogen into nitrite nitrogen, while anaerobic ammonia oxidation converts the remaining ammonia nitrogen and nitrite nitrogen into nitrogen gas and nitrate nitrogen. The resulting nitrate nitrogen and the nitrate nitrogen that did not react in the anoxic zone are then converted into nitrogen gas and nitrate nitrogen. Nitrate nitrogen is returned to the anoxic zone via liquid return path 9, forming a nitrogen cycle. This achieves partial coupling of short-cut denitrification and ammonia oxidation-anaerobic ammonia oxidation within the same reactor, eliminating the need for multi-stage equipment in series and reducing equipment costs. Carbon is supplied by the COD inherent in the ammonia-containing wastewater, eliminating the need for an external carbon source and reducing treatment costs. Nitrate nitrogen is regenerated by returning nitrate nitrogen to the anoxic zone for further short-cut denitrification, eliminating the need for additional reactors to remove residual nitrate nitrogen and further reducing equipment costs. Moreover, the plant's footprint is reduced by 40% compared to the traditional A / O process. When using the denitrification device provided by this invention for denitrification treatment, the device first undergoes a start-up phase: sludge 3 containing short-cut denitrifying bacteria and anaerobic ammonia oxidizing bacteria is inoculated into the anoxic zone, allowing the ammonia-containing wastewater to undergo short-cut denitrification to obtain nitrite-containing wastewater; then, the first nitrite-containing wastewater enters the aeration zone, where bubble-free aeration is supplied to the aeration zone through the membrane module 4, causing anaerobic ammonia oxidizing bacteria and ammonia oxidizing bacteria (ammonia oxidizing bacteria are converted from anaerobic ammonia oxidizing bacteria) to grow on the membrane module 4, thus converting the obtained nitrite-containing wastewater into denitrified purified water. After continuous and stable operation for 7 days, the device can be successfully started up without the need to start multiple reactors separately. A successful start-up once enables the stable operation of the entire device, shortening the start-up cycle by approximately 50% compared to traditional denitrification devices. Moreover, the present invention uses membrane module 4 for bubble-free aeration and oxygen supply, which improves the utilization rate of oxygen and reduces aeration energy consumption by 30-50% compared with traditional denitrification devices. At the same time, this oxygen supply method maintains low dissolved oxygen in the aeration zone, thereby inhibiting the growth of NOB (nitrite oxidizing bacteria). In addition, no bubbles are generated during the aeration and oxygen supply process, and the biofilm on membrane module 4 will not be detached due to friction, thereby improving the operational stability of the device.

[0016] The method for denitrification of ammonia-containing wastewater provided by this invention is simple to operate, has a short process, low cost, and is suitable for industrial-scale denitrification of ammonia-containing wastewater. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the denitrification device provided by the present invention; Figure 2 This is a schematic diagram of another denitrification device provided by the present invention; Figures 1-2In the middle, 1-inlet, 2-gas stirring component, 3-sludge, 4-membrane component, 5-sludge discharge port, 6-gas compression component, 7-dissolved oxygen detection component, 8-pH detection component, 9-liquid return path, 10-exhaust port, 11-outlet, 12-alkali replenishment device, 13-reaction vessel, 14-first pump, 15-second pump, 16-sewage tank, 17-gas return path, 18-biological carrier. Detailed Implementation

[0018] This invention provides a denitrification device, comprising: The reactor 13 has a cavity divided into an aeration zone and an anoxic zone from top to bottom. The bottom of the reactor 13 is provided with an inlet 1 that connects to the anoxic zone, and the top of the reactor 13 is provided with an outlet 11 that connects to the aeration zone. Membrane module 4, which is disposed in the aeration zone and is capable of supplying oxygen to the aeration zone without bubbles; Liquid reflux path 9 is located outside the reactor 13 and connects the oxygenation zone and the oxygen-deficient zone.

[0019] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0020] Figure 1 This is a schematic diagram of the denitrification device provided by the present invention; Figure 2 Here is a schematic diagram of another denitrification device provided by the present invention, which is described below in conjunction with... Figure 1 and Figure 2 The denitrification apparatus and method provided by the present invention will be described in detail.

[0021] The denitrification device provided by the present invention includes a reactor 13, wherein the cavity of the reactor 13 is divided into an aeration zone and an anoxic zone from top to bottom, and an inlet 1 communicating with the anoxic zone is provided at the bottom of the reactor 13; and an outlet 11 communicating with the aeration zone is provided at the top of the reactor 13.

[0022] In this invention, the reactor 13 may be made of stainless steel, specifically 304 stainless steel; the inlet 1 can be used to introduce ammonia-nitrogen-containing wastewater; the outlet 11 can be used to discharge denitrified purified water; the anoxic zone of the reactor 13 is used to house sludge 3 containing short-range denitrifying bacteria. By placing the inlet 1 at the bottom of the reactor 13 and the outlet 11 at the top, this invention allows ammonia-nitrogen-containing wastewater to enter from the bottom and denitrified purified water to exit from the top, with the fluid flowing from bottom to top, resulting in more thorough denitrification of the ammonia-nitrogen-containing wastewater and a more complete reaction.

[0023] The denitrification device provided by the present invention includes a membrane module 4, which is disposed in an aeration zone and is capable of supplying oxygen to the aeration zone without bubbles.

[0024] In this invention, the membrane module 4 can be used to grow a biofilm; specifically, the membrane module 4 can be a MABR membrane module. This invention uses a MABR membrane module that allows only oxygen to permeate. Oxygen can be precisely supplied to ammonia-oxidizing bacteria in the form of molecular diffusion, allowing oxygen to be used for the ammonia oxidation reaction without diffusing to the lower anoxic zone, unlike traditional aeration.

[0025] In this invention, the membrane module 4 may include a plurality of membrane bundles formed by hollow membrane filaments; the number of membrane bundles can be 6 to 12, specifically 6, 8, 10, or 12; the spacing between two adjacent membrane bundles can be 30 to 50 mm, specifically 30 mm, 35 mm, 40 mm, 45 mm, or 50 mm; a single membrane bundle can be vertically distributed. This invention employs membrane bundles formed by hollow membrane filaments (modular design), allowing anaerobic ammonia-oxidizing bacteria and ammonia-oxidizing bacteria to accumulate and grow on the surface of the membrane filaments, forming a stable biofilm layer, enabling the membrane module 4 to perform both oxygen transfer and microbial attachment functions; moreover, by controlling the spacing between membrane bundles and ensuring their vertical distribution, this invention guarantees good water flow distribution and shear force, avoiding localized membrane blockage. The vertical installation of the membrane module 4 ensures stable separation of the aeration and anoxic zones, and minimizes the footprint.

[0026] In this invention, the hollow membrane filaments may be made of polyvinylidene fluoride; the pore size of a single hollow membrane filament may be 0.05~0.2μm, specifically 0.05μm, 0.1μm, 0.15μm, or 0.2μm; the effective membrane specific surface area per unit volume may be 2000~5000m². 2 / m 3 Specifically, it can be 2000m 2 / m 3 3000m 2 / m 3 4000m 2 / m 3 or 5000m 2 / m 3 .

[0027] In this invention, the membrane bundle can specifically be a detachable membrane bundle. By employing a membrane module 4 with a detachable membrane bundle, the membrane area can be increased or decreased according to the actual operating load, facilitating the maintenance and replacement of the membrane module 4.

[0028] In this invention, a gas manifold may be provided at the lower part of the membrane module 4; the gas manifold may specifically be a gas manifold box. By providing a gas manifold, this invention allows the remaining non-oxygen gas after bubble-free aeration and oxygen supply using the membrane module 4 to continue flowing within the membrane cavity of the hollow membrane fibers and to converge into the gas manifold for gas stirring in the anoxic zone.

[0029] The denitrification device provided by the present invention includes a liquid reflux path 9, which is located outside the reaction vessel 13 and connects the aeration zone and the anoxic zone.

[0030] In this invention, the liquid reflux path 9 can specifically be a reflux pipe; the fluid flow direction in the liquid reflux path 9 can be a reflux from the self-aeration zone to the anoxic zone. In this invention, the lower end of the reflux pipe can be connected to the inlet 1, allowing the refluxed fluid to re-enter the reactor 13 through the inlet 1. In this invention, the height of the uppermost end of the liquid reflux path 9 can be lower than the height of the outlet 11. By setting up the liquid reflux path 9, this invention allows some unreacted NO3 to be... - NO generated by reaction with the aeration zone 3- Flowing back to the anoxic zone further reduces NO 3- In the hypoxic region, it is reduced to NO. 2- This improved the removal rate of ammonia nitrogen-containing wastewater.

[0031] The denitrification device provided by the present invention may further include a gas stirring component 2, which is disposed at the bottom of the anoxic zone.

[0032] In this invention, the gas stirring assembly 2 may include a gas microporous diffuser; the pore diameter of the gas microporous diffuser may be 20~80μm, specifically 20μm, 40μm, 60μm or 80μm; the pore density of the gas microporous diffuser may be 300~500 pores / cm³. 2 Specifically, it can be 300 pieces / cm 2 350 pieces / cm 2 400 pieces / cm 2 450 pieces / cm 2 Or 500 pieces / cm 2In this invention, the gas stirring component 2 can be connected to the membrane module 4; the gas stirring component 2 can also be connected to the gas manifold of the membrane module 4 via a gas guide pipe. By setting the gas stirring component 2 at the bottom of the anoxic zone and connecting it to the membrane module 4, the non-oxygen gas formed after bubble-free aeration and oxygen supply in the membrane module 4 flows into the gas manifold and is then guided to the gas stirring component 2 via the gas guide pipe before being released. This stirs the sludge 3 in the anoxic zone, preventing sludge sedimentation. No mechanical stirring is required, enhancing the mass transfer and contact efficiency between ammonia-nitrogen-containing wastewater and sludge, and promoting the formation of new sludge particles.

[0033] The denitrification device provided by the present invention may further include a gas compression component 6, which is connected to the membrane component 4.

[0034] In this invention, the gas compression assembly 6 can specifically be an air compressor; the gas compression assembly 6 can be connected to the air inlet pipe of the membrane module 4 via a flange interface or a threaded interface. In this invention, the gas compression assembly 6 may also include a distributor. In this invention, oxygen-containing gas (such as air) is supplied to the membrane module 4 through the gas compression assembly 6. After entering the membrane module 4 through the air inlet pipe, the oxygen-containing gas is split (for example, through a distributor). Oxygen diffuses through the membrane fibers of the membrane module 4 to the outside of the membrane and enters the aeration zone. The remaining non-oxygen gas enters the gas stirring assembly 2 and is released. The gas compression assembly 6 provides stirring power to stir the sludge 3.

[0035] The denitrification device provided by the present invention may further include an alkali replenishment device 12, which is connected to the anoxic zone. In the present invention, the alkali replenishment device 12 may be connected to the inlet 1.

[0036] The denitrification device provided by this invention may further include a first pump 14, which is disposed in the passage connecting the alkali replenishment device 12 and the anoxic zone. When the pH value of the aeration zone is lower than the target range, this invention pumps alkali solution into the reaction system through the alkali replenishment device 12. The alkali solution enters the aeration zone with the rising water flow, neutralizing the acid produced by the ammonia oxidation reaction and ensuring the synergistic denitrification activity of anaerobic ammonia oxidizing bacteria and ammonia oxidizing bacteria in the aeration zone.

[0037] The denitrification device provided by the present invention may further include a dissolved oxygen detection component 7, which is used to detect the concentration of dissolved oxygen in the anoxic zone and the aeration zone.

[0038] The denitrification device provided by the present invention may further include a pH detection component 8, which is used to detect the pH value in the anoxic zone and the aeration zone.

[0039] The denitrification device provided by this invention may further include an exhaust port 10, which is disposed at the top of the reaction vessel 13. In this invention, the exhaust port 10 may be connected to the gas stirring assembly 2, and the exhaust port 10 and the gas stirring assembly 2 are connected through a gas return path 17. In this invention, the gas return path 17 may include a gas return pipe; the gas flow direction in the gas return path 17 may be from the exhaust port 10 back to the gas stirring assembly 2. By setting the exhaust port 10 and the gas return path 17, this invention allows the nitrogen gas generated by the reaction in the aeration zone to be discharged through the exhaust port 10 and transported along the gas return path 17 to the gas stirring assembly 2 for stirring the sludge 3.

[0040] The denitrification device provided by the present invention may further include a second pump 15, which is disposed on the sewage inlet passage.

[0041] The denitrification device provided by the present invention may further include a wastewater tank 16, which is connected to the inlet 1; the second pump 15 may be installed on the passage connecting the wastewater tank 16 and the inlet 1. By setting up the wastewater tank 16, the present invention regulates the water quality of the ammonia-nitrogen-containing wastewater entering the reactor 13, thereby avoiding the impact load of the ammonia-nitrogen-containing wastewater on the reactor 13.

[0042] The denitrification device provided by the present invention may further include a sludge discharge port 5, which is located at the bottom of the reactor 13.

[0043] The present invention also provides a method for denitrification treatment using the denitrification device described above, including a start-up phase and an operation phase; The start-up phase includes: inoculating the anoxic zone of the reactor 13 with sludge 3 containing short-cut denitrifying bacteria and anaerobic ammonia oxidizing bacteria; transporting the first ammonia nitrogen-containing wastewater to the anoxic zone of the reactor 13 through the inlet 1 to carry out the first short-cut denitrification reaction to obtain the first nitrite nitrogen-containing wastewater; the dissolved oxygen concentration in the anoxic zone is <0.2 mg / L; The first wastewater containing nitrite nitrogen is introduced into the aeration zone, where it is supplied with oxygen through the membrane module 4 using bubble-free aeration. This allows anaerobic ammonia-oxidizing bacteria and ammonia-oxidizing bacteria to grow on the membrane module 4, and the first wastewater containing nitrite nitrogen undergoes a first ammonia oxidation-anaerobic ammonia oxidation reaction to obtain the first denitrified purified water. The dissolved oxygen concentration in the aeration zone is 0.2~0.4 mg / L. The denitrification unit is considered to have started successfully when the total nitrogen removal rate in the denitrification unit is ≥80% and it has been running stably for ≥7 days. The operation phase includes: after successful startup, the second ammonia nitrogen-containing wastewater is transported through inlet 1 to the anoxic zone of reactor 13 for a second short-range denitrification reaction to obtain the second nitrite nitrogen-containing wastewater; the second nitrite nitrogen-containing wastewater enters the aeration zone for a second ammonia oxidation-anaerobic ammonia oxidation reaction to obtain the second denitrified purified water.

[0044] The start-up phase of this invention includes: inoculating the anoxic zone of reactor 13 with sludge 3 containing short-cut denitrifying bacteria and anaerobic ammonia-oxidizing bacteria; and conveying the first ammonia-nitrogen-containing wastewater to the anoxic zone of reactor 13 through inlet 1 for a first short-cut denitrification reaction to obtain the first nitrite-nitrogen-containing wastewater. In this invention, the dissolved oxygen concentration in the anoxic zone is <0.2 mg / L, specifically 0.18 mg / L, 0.15 mg / L, 0.1 mg / L, 0.05 mg / L, or 0 mg / L.

[0045] In the initial stage of this invention, the sludge 3 is acclimated sludge; the source of the acclimated sludge can be denitrification sludge from the denitrification section of pharmaceutical and / or chemical water treatment; the biomass in the sludge 3 can be 3000~5000 mg / L, specifically 3000 mg / L, 3500 mg / L, 4000 mg / L, 4500 mg / L or 5000 mg / L; the filling rate of the sludge 3 in the reactor 13 can be 30~50%, specifically 30%, 35%, 40%, 45% or 50%.

[0046] In this invention, the start-up phase may further include adding a biological carrier 18 to the anoxic zone; the filling rate of the biological carrier 18 in the anoxic zone can be 30-50%, specifically 30%, 35%, 40%, 45%, or 50%; the material of the biological carrier 18 may include polyurethane sponge. This invention, by adding the biological carrier 18 to the anoxic zone, allows some short-range denitrifying bacteria and anaerobic ammonia oxidizing bacteria to grow on the biological carrier 18, avoiding the loss of these bacteria due to continuous water flow impact.

[0047] In this invention, the first ammonia-nitrogen-containing wastewater can be aquaculture wastewater and / or high-ammonia-nitrogen industrial wastewater, and the first ammonia-nitrogen-containing wastewater can be stored in wastewater pond 16. In this invention, the ammonia nitrogen concentration of the first ammonia-nitrogen-containing wastewater can be 100~1500 mg / L, specifically 100 mg / L, 500 mg / L, 1000 mg / L or 1500 mg / L; the total nitrogen concentration of the first ammonia-nitrogen-containing wastewater can be 200~2000 mg / L, specifically 200 mg / L, 500 mg / L, 1000 mg / L, 1500 mg / L or 2000 mg / L; and the COD of the first ammonia-nitrogen-containing wastewater can be 50~300 mg / L, specifically 50 mg / L, 100 mg / L, 200 mg / L or 300 mg / L.

[0048] In this invention, the first ammonia-nitrogen-containing wastewater further includes pretreatment before treatment; the pretreatment steps include: filtering and degreasing the first ammonia-nitrogen-containing wastewater before storing it in wastewater tank 16. In this invention, the filtration may include bar screen filtration; the bar screen filtration includes sequential coarse bar filtration and fine bar filtration; the pore size of the coarse bar used in the coarse bar filtration can be 10~50mm, specifically 10mm, 20mm, 30mm, 40mm, or 50mm; the pore size of the fine bar used in the fine bar filtration can be 1~10mm, specifically 1mm, 3mm, 5mm, 7mm, or 10mm. This invention intercepts large suspended solids in the first ammonia-nitrogen-containing wastewater through coarse and fine bar filtration, protecting the subsequent pumps and membrane modules from entanglement or wear.

[0049] In this invention, the device used for grease removal may include an air flotation tank. This invention, by removing grease, avoids grease encapsulating sludge particles.

[0050] In this invention, the pH value of the first short-cut denitrification reaction can be 7-8, specifically 7, 7.2, 7.5, 7.8, or 8. In this invention, the hydraulic retention time in the reactor 13 can be 12-36 hours, specifically 12 hours, 18 hours, 24 hours, 30 hours, or 36 hours. In this invention, the reaction occurring during the short-cut denitrification reaction is: 4NO3 - +CH3COO - →4NO2 - +2CO2+OH - +H2O.

[0051] After obtaining the first nitrite-containing wastewater, the present invention introduces the first nitrite-containing wastewater into the aeration zone, and supplies oxygen to the aeration zone through the membrane module 4 by bubble-free aeration, so that anaerobic ammonia oxidizing bacteria and ammonia oxidizing bacteria grow on the membrane module 4, and the first nitrite-containing wastewater undergoes a first ammonia oxidation-anaerobic ammonia oxidation reaction to obtain the first denitrified purified water; the dissolved oxygen concentration in the aeration zone is 0.2~0.4 mg / L.

[0052] In this invention, the membrane assembly 4 can be pressurized with oxygen-containing gas through the gas compression assembly 6; the oxygen-containing gas can be air.

[0053] In this invention, anaerobic ammonia-oxidizing bacteria and ammonia-oxidizing bacteria are enriched and grown on the membrane module 4 to form a biofilm. In this invention, the dissolved oxygen concentration in the aeration zone is 0.2~0.4 mg / L, which can be 0.25~0.35 mg / L, specifically 0.2 mg / L, 0.25 mg / L, 0.3 mg / L, 0.35 mg / L, or 0.4 mg / L. In this invention, a portion of the first denitrification purified water is discharged through the outlet 11; the remaining first denitrification purified water is returned to the anoxic zone through the liquid return path 9. In this invention, the return ratio (return water volume / inlet water volume) can be 0.5~1, which can also be 0.5~0.8, specifically 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0054] In this invention, the pH value of the second ammonia oxidation-anaerobic ammonia oxidation reaction can be 7.5~8.5, specifically 7.5, 7.8, 8, 8.2 or 8.5. In this invention, the reaction occurring during the ammonia oxidation-anaerobic ammonia oxidation reaction is: 2NH4+ + +3O2→2NO2 - +4H + +2H₂O (ammonia oxidation reaction); NH₄ + +1.32NO2 - +0.066HCO3 - +0.13H + →1.02N2+0.26NO3 - (Anaerobic ammonia oxidation reaction). In the ammonia oxidation-anaerobic ammonia oxidation reaction process of the present invention, the nitrite nitrogen obtained by short-range denitrification provides an electron acceptor for anaerobic ammonia oxidizing bacteria, maintains the activity of anaerobic ammonia oxidizing bacteria, and avoids the accumulation of nitrite nitrogen.

[0055] In this invention, the non-oxygen gas formed after the oxygen-containing gas in the membrane module 4 is aerated without bubbles can be guided through the guide pipe to the gas stirring component 2 to agitate the sludge 3. In this invention, the nitrogen gas generated by the ammonia oxidation-anaerobic ammonia oxidation reaction can be discharged through the exhaust port 10 and transported along the gas return path 17 to the gas stirring component 2 for agitating the sludge 3.

[0056] In this invention, the denitrification device is considered to have been successfully started when the total nitrogen removal rate in the denitrification device is ≥80% and it has been running stably for ≥7 days.

[0057] The operation phase of this invention includes: after successful startup, the second ammonia nitrogen-containing wastewater is transported through inlet 1 to the anoxic zone of reactor 13 for a second short-range denitrification reaction to obtain the second nitrite nitrogen-containing wastewater; the second nitrite nitrogen-containing wastewater enters the aeration zone for a second ammonia oxidation-anaerobic ammonia oxidation reaction to obtain the second denitrified purified water.

[0058] In this invention, the ammonia nitrogen concentration, total nitrogen concentration, and COD of the second ammonia nitrogen-containing wastewater can be the same as those of the first ammonia nitrogen-containing wastewater, and will not be repeated here. In this invention, the parameters and pretreatment methods of the second ammonia nitrogen-containing wastewater can be the same as those of the first ammonia nitrogen-containing wastewater, and will not be repeated here.

[0059] In this invention, the conditions for the second short-range denitrification reaction can be the same as those for the first short-range denitrification reaction, and will not be repeated here.

[0060] In this invention, the conditions for the second ammonia oxidation-anaerobic ammonia oxidation reaction can be the same as those for the first ammonia oxidation-anaerobic ammonia oxidation reaction, and will not be repeated here.

[0061] In this invention, the ammonia nitrogen concentration of the second denitrification purified water can be <5 mg / L; specifically, it can be 1 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, or 4.5 mg / L; the total nitrogen concentration of the second denitrification purified water can be <10 mg / L; specifically, it can be 2 mg / L, 4 mg / L, 6 mg / L, 8 mg / L, or 9 mg / L; the COD of the second denitrification purified water can be <50 mg / L; specifically, it can be 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, or 45 mg / L.

[0062] In the operational phase described in this invention, the mixed liquor suspended solids (MLSS) concentration in the reaction vessel 13 can be 4000~8000 mg / L, specifically 4000 mg / L, 5000 mg / L, 6000 mg / L, 7000 mg / L, or 8000 mg / L. When the ammonia nitrogen concentration in the second denitrification purified water is >10 mg / L, or the nitrite nitrogen concentration in the second denitrification purified water is >5 mg / L, this invention may further include replenishing fresh sludge. In this invention, the amount of fresh sludge replenished can be 20~40 wt% of the total sludge volume in the operational phase. This invention restores the microbial community balance by replenishing fresh sludge.

[0063] In the operational phase described in this invention, the particle size of the sludge 3 can be 1~2.5mm, specifically 1mm, 1.5mm, 2mm, or 2.5mm. In this invention, the particle size of the sludge particles can be controlled by adjusting the flow rate of oxygen-containing gas supplied to the membrane module 4 by the gas compression component 6; the flow rate of the oxygen-containing gas can be 0.05~0.1m³. 3 / (m 3 ·h), which can be specifically 0.05m 3 / (m 3 ·h), 0.06m 3 / (m 3 ·h), 0.07m 3 / (m 3 ·h), 0.08m 3 / (m 3 ·h), 0.09m 3 / (m 3 ·h) or 1m 3 / (m 3 (h). This invention avoids the loss of sludge particles that are too small with the effluent by controlling the particle size of the sludge particles, and also avoids the limitation of mass transfer caused by sludge particles that are too large.

[0064] In this invention, the second denitrification purified water can be used as a source of recycled water. After the invention is started and operates stably, the second denitrification purified water discharged can be used for factory area flushing, greening irrigation, toilet flushing, or cooling water replenishment after filtration or disinfection.

[0065] To further illustrate the present invention, the solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0066] Example 1 use Figure 1 The denitrification device shown performs denitrification treatment, and the specific steps are as follows: Start-up phase: Sludge 3 (biomass of 4000 mg / L, sourced from a municipal wastewater treatment plant) containing short-cut denitrifying bacteria and anaerobic ammonia oxidizing bacteria is inoculated into the anoxic zone of reactor 13, and polyurethane sponge is added as a biological carrier 18. Wastewater containing ammonia nitrogen with a concentration of 600 mg / L, a total nitrogen concentration of 800 mg / L, and a COD of 200 mg / L is transported to the anoxic zone of reactor 13 through inlet 1. The pH value of the anoxic zone is controlled at 7-8, and the dissolved oxygen concentration is controlled at 0 mg / L to carry out short-cut denitrification reaction, resulting in wastewater containing nitrite nitrogen. The first wastewater containing nitrite nitrogen is introduced into the aeration zone, where it is aerated without bubbles through membrane module 4, allowing anaerobic and ammonia-oxidizing bacteria to accumulate and grow on the membrane module 4, forming a biofilm. The pH value of the aeration zone is controlled at 7.5~8.5, and the dissolved oxygen concentration is controlled at 0.2~0.4 mg / L. The wastewater containing nitrite nitrogen undergoes an ammonia oxidation-anaerobic ammonia oxidation reaction in the aeration zone, resulting in denitrified purified water. Part of the denitrified purified water is discharged through outlet 11; the remaining denitrified purified water is returned to the anoxic zone through liquid return path 9. The non-oxygen gas formed after the oxygen-containing gas in membrane module 4 is aerated without bubbles is guided through the guide pipe to the gas stirring component 2 to agitate the sludge 3; the nitrogen gas produced by the ammonia oxidation-anaerobic ammonia oxidation reaction is discharged through exhaust port 10.

[0067] When the total nitrogen removal rate in the denitrification device is ≥80%, the ammonia nitrogen concentration of the denitrified purified water discharged from outlet 11 is ≤3mg / L, the total nitrogen concentration is ≤8mg / L, the COD is ≤40mg / L, and the device has been running stably for ≥7 days, the denitrification device is considered to have started successfully.

[0068] Operational Phase: After successful startup, ammonia-nitrogen-containing wastewater is transported through inlet 1 to the anoxic zone of reactor 13 for short-cut denitrification, yielding nitrite-containing wastewater. This nitrite-containing wastewater then enters the aeration zone for ammonia oxidation-anaerobic ammonia oxidation, producing denitrified purified water. A portion of aged sludge should be periodically measured and discharged. Every 40-60 days of operation, 10-15 wt% of aged sludge should be discharged to maintain the mixed liquor suspended solids concentration in the unit at 4000-8000 mg / L. When the effluent ammonia nitrogen concentration is detected to be >10 mg / L or the nitrite nitrogen concentration >5 mg / L, fresh activated sludge (20-40 wt% of the total sludge) should be added to restore the microbial community balance; the top gas flow rate should be controlled at 0.05-0.1 m³ / h. 3 / (m 3 / h), sludge age is adjusted to make the particle size of granular sludge 1.5~2.5mm.

[0069] According to the test results, after denitrification treatment, the ammonia nitrogen concentration of the denitrified purified water discharged from outlet 11 in this embodiment is <5mg / L and the total nitrogen concentration is <10mg / L, which meets the Class A standard of the National Integrated Wastewater Discharge Standard (GB8978-1996) and can be used for greening flushing or circulating cooling water replenishment.

[0070] Example 2 use Figure 2 The denitrification device shown performs denitrification treatment, and the specific steps are as follows: Start-up phase: Sludge 3 (biomass of 3500 mg / L, sourced from secondary sedimentation tank sludge of a wastewater treatment plant) containing short-cut denitrifying bacteria and anaerobic ammonia oxidizing bacteria is inoculated into the anoxic zone of reactor 13, and polyurethane sponge is added as a biological carrier 18. Wastewater containing ammonia nitrogen with a concentration of 300 mg / L, a total nitrogen concentration of 450 mg / L, and a COD of 120 mg / L is transported to the anoxic zone of reactor 13 through inlet 1. The pH value of the anoxic zone is controlled at 7-8 and the dissolved oxygen concentration is 0 mg / L to carry out short-cut denitrification reaction, resulting in wastewater containing nitrite nitrogen. The first wastewater containing nitrite nitrogen is introduced into the aeration zone, where it is aerated without bubbles through membrane module 4, allowing anaerobic ammonia oxidizing bacteria and ammonia-oxidizing bacteria to accumulate and grow on the membrane module 4, forming a biofilm. The pH value of the aeration zone is controlled at 7.5~8.5, and the dissolved oxygen concentration is controlled at 0.2~0.4 mg / L. The wastewater containing nitrite nitrogen undergoes an ammonia oxidation-anaerobic ammonia oxidation reaction in the aeration zone, resulting in denitrified purified water. Part of the denitrified purified water is discharged through outlet 11, and the remaining denitrified purified water is returned to the anoxic zone through liquid return path 9. The non-oxygen gas formed after the oxygen-containing gas in membrane module 4 is aerated without bubbles is guided through the guide pipe to the gas stirring component 2 to agitate the sludge 3. The nitrogen gas produced by the ammonia oxidation-anaerobic ammonia oxidation reaction is discharged through exhaust port 10 and transported along the gas return path 17 to the gas stirring component 2 for agitation of the sludge 3.

[0071] When the total nitrogen removal rate in the denitrification device is >80%, the ammonia nitrogen concentration of the denitrified purified water discharged from outlet 11 is <2mg / L, the total nitrogen concentration is <6mg / L, the COD is 30mg / L, and it has been running stably for ≥10 days, the denitrification device is considered to have started successfully and the denitrification treatment will continue using the parameters at the time of successful start-up.

[0072] Operational Phase: Wastewater containing ammonia nitrogen is transported through inlet 1 to the anoxic zone of reactor 13 for short-cut denitrification, yielding wastewater containing nitrite nitrogen. This nitrite nitrogen-containing wastewater then enters the aeration zone for ammonia oxidation-anaerobic ammonia oxidation, producing denitrified purified water. A portion of the aged sludge should be periodically measured and discharged. Every 40-60 days of operation, 10-15 wt% of aged sludge should be discharged to maintain the mixed liquor suspended solids concentration in the unit at 4000-8000 mg / L. When the effluent ammonia nitrogen concentration is detected to be >8 mg / L or the nitrite nitrogen concentration >3 mg / L, fresh activated sludge (20-40 wt% of the total sludge) should be added to restore the microbial community balance; the top gas flow rate should be controlled at 0.05-0.1 m³ / h. 3 / (m 3 •h) , to adjust the sludge age so that the particle size of the granular sludge is 1.5~2.5mm.

[0073] According to the test results, after denitrification treatment, the ammonia nitrogen concentration of the denitrified purified water discharged from outlet 11 in this embodiment is <5mg / L and the total nitrogen concentration is <10mg / L, which meets the Class A standard of the National Integrated Wastewater Discharge Standard (GB8978-1996) and can be used for greening flushing or circulating cooling water replenishment.

[0074] In summary, wastewater containing ammonia nitrogen is complex in quality and has a high concentration of ammonia nitrogen. Using a traditional two-stage PN / A system with mechanical aeration for oxygen supply presents problems such as complex process flow, high energy consumption, low oxygen utilization rate, unstable nitrogen circulation, and difficult operation and maintenance. Mechanical aeration results in an oxygen transfer efficiency of less than 20%, with unit energy consumption as high as 0.7~0.9 kWh / m³. 3 Traditional methods often involve high operating costs and are prone to oxygen leakage and decreased activity of anaerobic ammonia-oxidizing bacteria, making it difficult to consistently maintain a total nitrogen concentration below 15 mg / L in the effluent. However, the denitrification method provided by this invention increases oxygen utilization to over 70%, requires zero external carbon source, reduces energy consumption by approximately 40%, and achieves effluent ammonia nitrogen concentrations below 5 mg / L and total nitrogen concentrations below 10 mg / L. This achieves efficient, energy-saving, and stable denitrification of ammonia-containing wastewater. The denitrification device provided by this invention has a simple structure, stable operation, low cost, and strong resistance to shocks.

[0075] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A denitrification device, characterized in that, include: The reactor (13) has an aeration zone and an anoxic zone in its cavity from top to bottom. The bottom of the reactor (13) is provided with an inlet (1) that connects to the anoxic zone. The top of the reactor (13) is provided with an outlet (11) that connects to the aeration zone. Membrane module (4), the membrane module (4) is disposed in the aeration zone, and the membrane module (4) is capable of supplying oxygen to the aeration zone without bubbles; Liquid reflux path (9) is provided outside the reactor (13) and connects the oxygenation zone and the oxygen-deficient zone.

2. The denitrification device according to claim 1, characterized in that, The membrane module (4) comprises a membrane bundle formed by a plurality of hollow membrane filaments; the hollow membrane filaments are made of polyvinylidene fluoride; The pore size of a single hollow membrane filament is 0.05~0.2μm, and the effective membrane specific surface area per unit volume is 2000~5000m². 2 / m 3 .

3. The denitrification device according to claim 1 or 2, characterized in that, The denitrification device also includes: Gas stirring assembly (2), wherein the gas stirring assembly (2) is disposed at the bottom of the oxygen-deficient zone; A gas compression assembly (6) is connected to a membrane assembly (4); Alkali replenishment device (12), which is connected to the hypoxic zone.

4. The denitrification device according to claim 3, characterized in that, The denitrification device also includes: Dissolved oxygen detection component (7) and pH detection component (8); The first pump (14) is located on the passage connecting the alkali replenishment device (12) and the hypoxic zone; The second pump (15) is installed on the sewage inlet passage; An exhaust port (10) is located at the top of the reactor (13).

5. The denitrification device according to claim 4, characterized in that, The gas stirring assembly (2) is connected to the membrane assembly (4).

6. A method for denitrification treatment using the denitrification device according to any one of claims 1 to 5, characterized in that, Includes the startup phase and the operation phase; The start-up phase includes: inoculating the anoxic zone of the reactor (13) with sludge (3) containing short-range denitrifying bacteria and anaerobic ammonia oxidizing bacteria, and transporting the first ammonia nitrogen-containing wastewater to the anoxic zone of the reactor (13) through the inlet (1) to carry out the first short-range denitrification reaction to obtain the first nitrite nitrogen-containing wastewater; the dissolved oxygen concentration in the anoxic zone is <0.2 mg / L; The first nitrite-containing wastewater is introduced into the aeration zone, and oxygen is supplied to the aeration zone through the membrane module (4) without foaming. Anaerobic ammonia-oxidizing bacteria and ammonia-oxidizing bacteria grow on the membrane module (4), and the first nitrite-containing wastewater undergoes a first ammonia oxidation-anaerobic ammonia oxidation reaction to obtain the first denitrified purified water; the dissolved oxygen concentration in the aeration zone is 0.2~0.4 mg / L. The denitrification unit is considered to have started successfully when the total nitrogen removal rate in the denitrification unit is ≥80% and it has been running stably for ≥7 days. The operation phase includes: after the start-up is successful, the second ammonia nitrogen-containing wastewater is transported through the inlet (1) to the anoxic zone of the reactor (13) for the second short-range denitrification reaction to obtain the second nitrite nitrogen-containing wastewater; the second nitrite nitrogen-containing wastewater enters the aeration zone for the second ammonia oxidation-anaerobic ammonia oxidation reaction to obtain the second denitrified purified water.

7. The method according to claim 6, characterized in that, During the start-up phase, the biomass in the sludge (3) is 3000~5000 mg / L; the filling rate of the sludge (3) in the reactor (13) is 30~50%.

8. The method according to claim 7, characterized in that, The start-up phase also includes the addition of biological carriers (18) in the hypoxic zone. The biological carrier (18) has a filling rate of 30-50% in the hypoxic zone.

9. The method according to claim 7 or 8, characterized in that, The ammonia nitrogen concentration of the first and second ammonia nitrogen-containing wastewaters is independently 100~1500 mg / L, the total nitrogen concentration is independently 200~2000 mg / L, and the COD is independently 50~300 mg / L; The ammonia nitrogen concentration of the second denitrification purified water is <5 mg / L, the total nitrogen concentration is <10 mg / L, and the COD is <50 mg / L.

10. The method according to claim 7 or 8, characterized in that, The pH values ​​of the first short-cut denitrification reaction and the second short-cut denitrification reaction are independently 7 to 8; the pH values ​​of the first ammonia oxidation-anaerobic ammonia oxidation reaction and the second ammonia oxidation-anaerobic ammonia oxidation reaction are independently 7.5 to 8.5.

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