Device and method for enhancing advanced denitrification of municipal sewage based on SDR-AOA process

Abstract

This invention discloses a device and method for enhanced deep denitrification of urban wastewater based on the SDR-AOA process. The device includes an anaerobic tank, an aerobic tank, a microaerobic PN / A integrated reactor, an intermediate sedimentation tank, a post-anoxic tank, an aeration tank, a terminal sedimentation tank, bypass pipeline I, and bypass pipeline II. The anaerobic tank, aerobic tank, and microaerobic PN / A integrated reactor are connected in sequence. Raw water enters the anaerobic tank as influent and the microaerobic PN / A integrated reactor as effluent before entering the intermediate sedimentation tank for sludge-water separation. A portion of the bottom sludge is returned to the anaerobic tank as recycled sludge. The supernatant sequentially enters the post-anoxic tank and the aeration tank, and then... The process involves separating sludge and water in the final sedimentation tank. The supernatant is discharged as the final effluent, while part of the bottom sludge is returned to the aerobic tank as recycled sludge, and the other part is discharged as excess sludge. Simultaneously, the anaerobic tank is connected to the integrated micro-aerobic PN / A reactor via bypass pipe I. When bypass pipe I is open, the anaerobic tank and the aerobic tank are not connected. The integrated micro-aerobic PN / A reactor is connected to the post-anoxic tank via bypass pipe II. When bypass pipe II is open, the integrated micro-aerobic PN / A reactor and the intermediate sedimentation tank are not connected. Both bypass pipes I and II are open when water quality parameters are within the specified concentration range. This invention improves denitrification efficiency, enhances treatment capacity, and ultimately achieves the goal of deep denitrification and synergistic carbon reduction in urban wastewater.

Description

Technical Field

[0001] This invention relates to the field of urban wastewater advanced treatment technology, specifically to a device and method for enhancing urban wastewater advanced denitrification based on the SDR-AOA process. Background Technology

[0002] Currently developed new wastewater treatment processes show good results in treating specific types of wastewater, such as landfill leachate and sludge digestion liquid, which are high in ammonia nitrogen and high in organic matter. However, due to limitations in process flow, reaction conditions, and operating parameters, some treatment technologies are applicable to relatively singular and fixed influent water qualities. Since the water quality of urban wastewater fluctuates with regional and seasonal changes, they cannot achieve universal applicability, making further promotion for future engineering applications difficult. In response to the aforementioned problems, some new processes, after modification, can switch between anaerobic, anoxic, and aerobic operating modes according to different influent water quality conditions. However, when water quality fluctuates significantly, the system needs to switch frequently, which can alter the species and stability of the microbial community within some units, affecting the treatment effect of that section to some extent.

[0003] Secondly, current biological denitrification technologies generally employ the activated sludge process to treat urban wastewater for nitrogen and phosphorus removal. However, due to the lack of carbon sources required for the denitrification process in urban wastewater, the biological treatment efficiency is low, making it difficult to meet discharge standards. To improve effluent quality, wastewater treatment plants typically need to add additional carbon sources (such as ethanol, methanol, sodium acetate, etc.) to enhance denitrification and phosphorus removal efficiency. This practice not only increases wastewater treatment costs but also increases the production of excess sludge.

[0004] Short-cut nitrification-anaerobic ammonium oxidation (PN / A) is currently the most promising autotrophic nitrogen removal technology. One of its variants, the integrated short-cut nitrification-anaerobic ammonium oxidation process, has certain advantages in terms of saving land and shortening the treatment process. However, since the activity of anaerobic ammonium oxidizing bacteria is easily affected by the organic matter and dissolved oxygen concentration of the influent, if only an integrated device is set up, the system treatment efficiency may change with the fluctuation of the influent water quality. Summary of the Invention

[0005] In view of this, the present invention provides a device and method for enhancing deep denitrification of urban wastewater based on the SDR-AOA process. Based on the segmented short-cut nitrification-anaerobic ammonia oxidation technology, the anoxic section in the traditional AAO operation mode is moved to the end, and packing is introduced to realize the AOA operation mode of the system. Combined with the mud-film mixing strategy, the denitrification efficiency is improved, the treatment capacity is enhanced, and the goal of deep denitrification and carbon reduction of urban wastewater is ultimately achieved.

[0006] The technical solution adopted in this invention is as follows:

[0007] A device for enhancing deep denitrification of urban sewage based on SDR-AOA process includes an anaerobic tank, an aerobic tank, a micro-aerobic PN / A integrated reaction tank, an intermediate sedimentation tank, a post-anoxic tank, an aeration tank, an end sedimentation tank, bypass pipeline I, and bypass pipeline II.

[0008] The anaerobic tank, aerobic tank, and microaerobic PN / A integrated reactor are connected in sequence. The microaerobic PN / A integrated reactor is equipped with a polyurethane sponge packing frame. The raw water enters the anaerobic tank and exits the microaerobic PN / A integrated reactor, and then enters the intermediate sedimentation tank to achieve sludge-water separation. Part of the bottom sludge is returned to the anaerobic tank as return sludge, and the other part is discharged as excess sludge. The supernatant is used as effluent and enters the post-anoxic tank and aeration tank in sequence, and then enters the final sedimentation tank to achieve sludge-water separation. The supernatant of the final sedimentation tank flows out as the final effluent, and part of the bottom sludge of the final sedimentation tank is returned to the aerobic tank as return sludge, and the other part is discharged as excess sludge.

[0009] Meanwhile, the anaerobic tank is connected to the microaerobic PN / A integrated reactor via bypass pipe I. When bypass pipe I is open, the anaerobic tank and the aerobic tank are not connected. The microaerobic PN / A integrated reactor is connected to the post-anoxic tank via bypass pipe II. When bypass pipe II is open, the microaerobic PN / A integrated reactor and the intermediate sedimentation tank are not connected. When the water quality parameters are within the specified concentration range, bypass pipe I and bypass pipe II are in the open state.

[0010] Furthermore, the specified concentration range is COD < 100 mg / L and NH4 < 100 mg / L. + -N < 30 mg / L.

[0011] Furthermore, the volume ratio of the anaerobic zone, the anoxic zone, and the aerobic zone is 1:4:3. The anoxic zone includes the first micro-aerobic PN / A integrated reactor, the second micro-aerobic PN / A integrated reactor, the first post-anoxic tank, and the second post-anoxic tank. The aerobic zone includes the first aerobic tank, the second aerobic tank, and the aeration tank.

[0012] Furthermore, the anaerobic tank, aerobic tank, and microaerobic PN / A integrated reaction tank are connected by water passage holes, and the post-anoxic tank, aeration tank, and terminal sedimentation tank are connected by water passage holes. Moreover, the water passage holes of each reaction tank are arranged in an alternating vertical manner.

[0013] Furthermore, agitators are installed in both the micro-aerobic PN / A integrated reaction tank and the post-anoxic tank; aeration discs are installed at the bottom of the aerobic tank, the micro-aerobic PN / A integrated reaction tank and the aeration tank, and aeration is carried out by blowers.

[0014] Furthermore, the post-anoxic tank is equipped with polyethylene hollow ring packing material with a suspended cylindrical structure.

[0015] This invention also provides a method for enhancing deep denitrification of urban wastewater based on the SDR-AOA process, using the aforementioned apparatus, and the method is as follows:

[0016] Raw water enters the anaerobic tank for ammoniation and phosphorus release reaction, and then enters the aerobic tank. At the same time, the return sludge in the intermediate sedimentation tank enters the anaerobic tank.

[0017] After entering the aerobic tank, semi-short-cut nitrification and organic matter degradation occur, while the return sludge in the terminal sedimentation tank enters the aerobic tank.

[0018] Then it enters the micro-aerobic PN / A integrated reactor for short-cut nitrification and anaerobic ammonia oxidation reactions;

[0019] The sludge enters the intermediate sedimentation tank to achieve sludge-water separation. Part of the bottom sludge is returned to the anaerobic tank as return sludge, and the other part is discharged as excess sludge.

[0020] Then it enters the post-anoxic tank for anaerobic ammonia oxidation reaction;

[0021] The raw water enters the aeration tank for further degradation of residual ammonia nitrogen, and finally enters the final sedimentation tank to achieve sludge-water separation. The supernatant flows out as the final effluent, and part of the bottom sludge is returned to the aerobic tank as return sludge, while the other part is discharged as excess sludge.

[0022] Furthermore, when the water quality parameters are within the specified concentration range, bypass pipe I and bypass pipe II are activated.

[0023] Furthermore, the sludge concentration range of the integrated micro-aerobic PN / A reactor is MLSS = 1500–2000 mg / L, while the sludge concentration range of other reactors is MLSS = 3000–5000 mg / L.

[0024] Furthermore, the dissolved oxygen concentration (DO) in the aerobic tank is set to a range of 2.0–3.0 mg / L, the dissolved oxygen concentration (DO) in the micro-aerobic PN / A integrated reactor is set to a range of 0.5–1.0 mg / L, and the dissolved oxygen concentration (DO) in the terminal aeration tank is set to a range of 3.0–4.0 mg / L; the sludge age (SRT) is 15–20 days; the sludge return ratio from the bottom of the intermediate settling tank to the anaerobic tank is R1 = 100%, and the sludge return ratio from the bottom of the sedimentation tank to the first aerobic tank is R2 = 100%.

[0025] When bypass pipeline I and bypass pipeline II are opened, the bypass ratio from the anaerobic tank to the first microaerobic PN / A integrated reactor is r1 = 50%, and the bypass ratio from the first microaerobic PN / A integrated reactor to the first post-anoxic tank is r2 = 50%.

[0026] Beneficial effects:

[0027] 1. The SDR-AOA process adopted in this invention can fully utilize the carbon source in the raw water, reduce or even eliminate the need for adding external carbon sources, achieve carbon emission reduction, and has high carbon source utilization and low energy consumption. Moreover, by utilizing the characteristic that the integrated PN / A process does not have a nitrite accumulation process, the short-cut nitrification process can be maintained stably. By setting up an overpass pipeline, the raw water distribution ratio can be adjusted according to the influent water quality to realize the conversion of multiple operating modes, thereby shortening the treatment process and reducing energy consumption. The second overpass can supplement the carbon source in the post-anoxic tank and optimize the microbial community state through macroscopic dynamic control.

[0028] Secondly, setting up a dual sludge recirculation system can further improve wastewater treatment efficiency. Since the dissolved oxygen concentration in the integrated reactor is low and the water quality is optimized after short-cut nitrification and anaerobic ammonia oxidation, the first recirculation system can maintain the sludge concentration without affecting the microbial community structure in the anaerobic reactor. Similarly, since the dissolved oxygen concentration in the terminal aeration tank is high, the second recirculation system can reduce the aeration volume in the front-end aerobic reactor, saving costs.

[0029] Furthermore, post-anaerobic tanks can remove nitrate nitrogen and residual nitrite nitrogen produced during anaerobic ammonia oxidation. At the same time, the intracellular carbon source stored in the cells after anaerobic treatment is used for the denitrification process of nitrate nitrogen in the anoxic zone, which can save organic carbon source in raw water to a certain extent. Compared with the traditional AAO process, this system can further improve the quality of effluent.

[0030] 2. The front-end aerobic reactor of this invention adopts a strategy of low-oxygen aeration (DO = 2.0-3.0 mg / L) and low sludge age (SRT = 15-20 days) to achieve semi-short-cut nitrification and provide substrate for the anaerobic ammonia oxidation process, while also saving aeration energy consumption to a certain extent.

[0031] 3. This invention introduces suspended hollow ring packing and polyurethane sponge packing, adopts the mud-film symbiosis method, applies the basic principles of biofilm, and makes full use of the advantages of activated sludge process to realize the activated sludge mode operation of biofilm process, improve the retention rate of key microorganisms, and enhance the denitrification effect through the synergistic effect between suspended sludge and biofilm.

[0032] 4. This invention adopts a continuous flow treatment system, in which the wastewater (raw water) to be treated undergoes continuous and uninterrupted treatment from influent to effluent. The process flow is simple and easy to control, which improves the ability to resist shock loads to a certain extent. The system has good denitrification performance. Under the condition that the influent is domestic sewage, the average total nitrogen removal rate exceeds 90%. It can be applied to various treatment scenarios such as high ammonia nitrogen and high concentration of organic wastewater, providing theoretical reference and technical support for engineering applications. Attached Figure Description

[0033] Figure 1This is a schematic diagram of the device of the present invention.

[0034] Among them, 1-raw water, 2-anaerobic reactor, 3-first aerobic reactor, 4-second aerobic reactor, 5-first microaerobic PN / A integrated reactor, 6-second microaerobic PN / A integrated reactor, 7-intermediate sedimentation tank, 8-first post-anoxic reactor, 9-second post-anoxic reactor, 10-aeration tank, 11-final sedimentation tank, 12-effluent, 13-agitator, 14-polyurethane sponge packing frame, 15-hollow ring packing, 16-aeration disc, 17-blower, 18-peristaltic pump. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] This invention provides a device for enhancing deep denitrification of urban wastewater based on the SDR-AOA process. The SDR-AOA process refers to an anaerobic / aerobic / anoxic sludge dual recirculation process, such as... Figure 1 As shown, the device includes an anaerobic reactor 2, a first aerobic reactor 3, a second aerobic reactor 4, a first microaerobic PN / A (short-cut nitrification-anaerobic ammonia oxidation) integrated reactor, a second microaerobic PN / A integrated reactor 6, an intermediate sedimentation tank 7, a first post-anoxic reactor 8, a second post-anoxic reactor 9, an aeration tank 10, an end sedimentation tank 11, bypass pipeline I, and bypass pipeline II.

[0037] Anaerobic reactor 2, aerobic reactor, and microaerobic PN / A integrated reactor are connected in sequence. The microaerobic PN / A integrated reactor is equipped with a polyurethane sponge packing frame 14. Raw water 1 enters anaerobic reactor 2 and effluent from the microaerobic PN / A integrated reactor, then flows through a top inlet pipe into intermediate sedimentation tank 7 to achieve sludge-water separation. Part of the bottom sludge is returned to anaerobic reactor 2 as return sludge, while the other part is discharged as excess sludge. In other words, a first return sludge system is established between intermediate sedimentation tank 7 and anaerobic reactor 2. The pipeline has a peristaltic pump installed on the first return pipeline. The supernatant is used as effluent and enters the post-anoxic reaction tank and aeration tank 10 in sequence, and then enters the terminal sedimentation tank 11 to achieve sludge-water separation. The supernatant of the terminal sedimentation tank 11 flows out as the final effluent 12. Part of the bottom sludge of the terminal sedimentation tank 11 is returned to the first aerobic reaction tank 3 as return sludge, and the other part is discharged as excess sludge. That is, there is a second return pipeline between the terminal sedimentation tank 11 and the first aerobic reaction tank 3, and a peristaltic pump 18 is installed on the second return pipeline.

[0038] Meanwhile, anaerobic reactor 2 is connected to the integrated microaerobic PN / A reactor via bypass pipe I. When bypass pipe I is open, anaerobic reactor 2 is not connected to the aerobic reactor. The integrated microaerobic PN / A reactor is connected to the post-anoxic reactor via bypass pipe II. When bypass pipe II is open, the integrated microaerobic PN / A reactor is not connected to the intermediate sedimentation tank 7. Water quality parameters are within the specified concentration range (COD < 100 mg / L, NH4+ < 100 mg / L). + When the concentration of -N < 30 mg / L, bypass line I and bypass line II are in the open state. Both bypass line I and bypass line II are equipped with peristaltic pumps.

[0039] The volume ratio of the anaerobic zone, anoxic zone, and aerobic zone is 1:4:3. The anoxic zone includes the first micro-aerobic PN / A integrated reactor 5, the second micro-aerobic PN / A integrated reactor 6, the first post-anoxic reactor 8, and the second post-anoxic reactor 9. The aerobic zone includes the first aerobic reactor 3, the second aerobic reactor 4, and the aeration tank 10. This ratio is not affected by the installation of bypass pipelines.

[0040] In this embodiment, the anaerobic reactor 2, the first aerobic reactor 3, the second aerobic reactor 4, the first microaerobic PN / A integrated reactor 5, and the second microaerobic PN / A integrated reactor 6 are connected by water passage holes. The first post-anoxic reactor 8, the second post-anoxic reactor 9, the aeration tank 10, and the terminal sedimentation tank 11 are also connected by water passage holes. To prevent short-circuiting, the water passage holes in each reactor are arranged in a staggered manner. Agitators 13 are installed in the first microaerobic PN / A integrated reactor 5, the second microaerobic PN / A integrated reactor 6, the first post-anoxic reactor 8, and the second post-anoxic reactor 9. Aeration discs 16 are installed at the bottom of the first aerobic reactor 3, the second aerobic reactor 4, the first microaerobic PN / A integrated reactor 5, the second microaerobic PN / A integrated reactor 6, and the aeration tank 10, and aeration is achieved by blowers 17. The post-anaerobic reaction tank is equipped with a suspended cylindrical polyethylene hollow ring packing material 15, with a diameter of 2.5 cm, a height of 1.2 cm, and a density of less than 1 g / cm³. 3 Specific surface area is 500m² 2 / m 3 The polyurethane sponge packing frame 14 installed in the anaerobic ammonia oxidation reactor has a filling ratio of 25-30% with sponge packing inoculated with anaerobic ammonia oxidizing bacteria, a porosity of 90-95%, and a specific surface area of ​​15,000-18,000 m². 2 / m 3 The bulk density is 15-20 kg / m³. 3 .

[0041] The operating mode and parameters of this device vary under different influent water quality conditions, mainly reflected in operating parameters such as hydraulic retention time (HRT), sludge concentration (MLSS), mixed liquor return ratio (R), and exceedance ratio (r). The retention time of wastewater in each individual reactor varies depending on the flow rate. Under normal conditions, the volume ratio of the anaerobic, anoxic, and aerobic zones is 1:4:3, the sludge retention time (SRT) is 15–20 days, the sludge concentration range in the micro-aerobic PN / A integrated reactor is MLSS = 1500–2000 mg / L, and the sludge concentration range in other reactors is MLSS = 3000–5000 mg / L. The dissolved oxygen concentration (DO) in the aerobic reactor is set to 2.0–3.0 mg / L, the DO in the micro-aerobic PN / A integrated reactor is set to 0.5–1.0 mg / L, and the DO in the terminal aeration tank is set to 3.0–4.0 mg / L.

[0042] Under normal circumstances, the influent water quality range of the system is: NH4 + -N is 40.0~60.0mg / L, NO3 - -N is 0-0.5 mg / L, NO2 - -N is 0–0.5 mg / L, TN is 50.0–70.0 mg / L, and COD is 150.0–300.0 mg / L. For the first 30 days of system operation, raw water 1 was artificially prepared. The chemicals and their concentrations (after addition) are shown in the table below:

[0043] Table 1 Concentration of Chemicals Used in Artificial Water Preparation

[0044]

[0045] Note: NH4Cl corresponds to NH4 + -N (as N) is 50.0 mg / L, the COD equivalent of glucose is 200.0 mg / L, and the PO4 content of KH2PO4 is... 3- -P (as P) is 5.0 mg / L, and the pH range controlled by NaHCO3 is 7.0 to 8.0.

[0046] The system's effluent water quality range is: NH4 + -N is 0~1.0mg / L, NO3 - -N is 0~1.0mg / L, NO2 - With -N ranging from 0 to 0.5 mg / L, TN from 1.0 to 3.0 mg / L, and COD from 10.0 to 30.0 mg / L, the effluent quality of this process can consistently exceed the Class A discharge standard.

[0047] Under normal operating conditions, the total hydraulic retention time (HRT) of the system is 23.0 h. The sludge return from the bottom of the intermediate sedimentation tank to the anaerobic reactor 2 (first return) ratio R1 = 100%, and the sludge return from the bottom of the sedimentation tank to the first aerobic reactor 3 (second return) ratio R2 = 100%. When bypass pipes I and II are open, the bypass ratio from the anaerobic reactor 2 to the first microaerobic PN / A integrated reactor 5 is r1 = 50%, and the bypass ratio from the first microaerobic PN / A integrated reactor 5 to the first post-anoxic reactor 8 is r2 = 50%. Under this operating mode, the total hydraulic retention time (HRT) of the system is 21.0 h.

[0048] This invention also provides a method for enhancing deep denitrification of urban wastewater based on the SDR-AOA process. Using the above-mentioned device, the main treatment process is as follows: raw water → anaerobic reactor → aerobic reactor → micro-aerobic PN / A integrated reactor → intermediate sedimentation tank → post-anoxic reactor → terminal aeration tank → terminal sedimentation tank → effluent.

[0049] The specific method is as follows:

[0050] Raw water 1 first enters anaerobic reactor 2 for ammonification and phosphorus release. Organic nitrogen compounds are decomposed into ammonia nitrogen by ammonifying microorganisms. Polyphosphate-accumulating bacteria release phosphorus while absorbing organic matter from the water. Additionally, heterotrophic microorganisms store organic matter within themselves as an internal carbon source. Returned sludge from intermediate sedimentation tank 7 also enters anaerobic reactor 2 to maintain the sludge concentration in the anaerobic tank. When the influent water quality is good, i.e., the water quality parameters are within the specified concentration range (COD < 100 mg / L, NH4+), the process continues. + When -N < 30 mg / L, open the valve on the bottom bypass pipe I, and part of the anaerobic raw water 1 directly enters the first micro-aerobic PN / A integrated reactor 5 to shorten the treatment process.

[0051] Next, the water enters the first aerobic reaction tank 3 and the second aerobic reaction tank 4. Under aerobic conditions, heterotrophic bacteria absorb and decompose most of the organic matter in the water, reducing the COD content. At the same time, nitrifying bacteria (AOB) undergo a semi-short-cut nitrification process in a low-oxygen environment (DO = 2.0-3.0 mg / L), reducing some of the NH4+ in the water. + Converted to NO2 - A very small amount of NO2 - Converted to NO3 - The first aerobic reaction tank 3 also contains returned sludge from the end sedimentation tank 11. The raw water 1, after being treated by the aeration tank 10, still contains a certain amount of dissolved oxygen, which can save the aeration volume of the first aerobic reaction tank 3. At the same time, the excessive phosphorus uptake process of polyphosphate-accumulating bacteria is also completed in this reaction tank.

[0052] Then it enters the first microaerobic PN / A integrated reactor 5 and the second microaerobic PN / A integrated reactor 6. Anaerobic ammonia-oxidizing bacteria and nitrifying bacteria accumulate from the inside out on the sponge packing after biofilm formation. In a microaerobic environment (DO = 0.5–1.0 mg / L), a short-cut nitrification process first occurs, where the nitrifying bacteria convert NH4+ into nitrogen dioxide. + Converted to NO2 - Then, an anaerobic ammonium oxidation process occurs, simultaneously converting both into N2 and a small amount of NO3. - When the influent water quality is relatively good (COD < 100 mg / L, NH4+), + When COD < 30 mg / L, open the valve on the bottom bypass pipe I, and the raw water 1, which has undergone anaerobic treatment, directly enters the first micro-aerobic PN / A integrated reactor 5. Since the COD and dissolved oxygen concentrations are both low, they will not affect the anaerobic ammonia oxidation process. At the same time, the NO3 generated during the anaerobic ammonia oxidation process... - It can be further removed by the action of denitrifying bacteria.

[0053] The sludge then enters intermediate sedimentation tank 7 for settling, achieving sludge-water separation. The supernatant is discharged as effluent into the next unit, while the remaining sludge is discharged as excess sludge. Furthermore, the intermediate sedimentation tank 7 also reduces the impact of dissolved oxygen and other substances in the aforementioned reaction tank on the subsequent anoxic section.

[0054] Next, the water enters the first post-anoxic reaction tank 8 and the second post-anoxic reaction tank 9. The denitrifying bacteria on the hollow ring packing 15 can use organic matter to denitrify the residual NO2 in the raw water 1. - and NO3 - It is converted into N2 when the influent water quality is relatively good (COD < 100 mg / L, NH4) + When -N < 30 mg / L, open the valve on the bottom bypass pipe II, and part of the mixed liquid in the first micro-aerobic PN / A integrated reaction tank 5 directly enters the first post-anoxic reaction tank 8. Since the concentration of organic matter in the influent is low, the bypass pipe II can reduce the consumption of organic carbon source and ensure the nitrogen removal effect in the subsequent anoxic section.

[0055] Upon entering the terminal aeration tank 10, nitrifying bacteria further degrade the residual ammonia nitrogen in the raw water 1. Under high dissolved oxygen conditions, residual organic matter in the water can also be further removed by heterotrophic bacteria.

[0056] Finally, the sediment enters the final sedimentation tank 11 for static settling to achieve sludge-water separation. The supernatant flows out of the system as the final effluent 12, and part of the bottom sludge is returned to the first aerobic reaction tank 3 as return sludge, and the other part is discharged from the system as excess sludge.

[0057] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for enhancing deep nitrogen removal from urban wastewater based on the SDR-AOA process, characterized in that, It includes an anaerobic tank, a first aerobic tank, a second aerobic tank, a microaerobic PN / A integrated reactor, an intermediate sedimentation tank, a post-anoxic tank, an aeration tank, an end sedimentation tank, bypass pipeline I, and bypass pipeline II; the dissolved oxygen concentration (DO) in the microaerobic PN / A integrated reactor is set to a range of 0.5~1.0 mg / L, and the microaerobic PN / A integrated reactor includes a first microaerobic PN / A integrated reactor and a second microaerobic PN / A integrated reactor; the post-anoxic tank includes a first post-anoxic reactor and a second post-anoxic reactor; The anaerobic tank, aerobic tank, and microaerobic PN / A integrated reactor are connected in sequence. The microaerobic PN / A integrated reactor is equipped with a polyurethane sponge packing frame, which is inoculated with anaerobic ammonia-oxidizing bacteria. The post-anoxic tank is equipped with polyethylene hollow ring packing with a suspended cylindrical structure. The raw water enters the anaerobic tank as influent and the microaerobic PN / A integrated reactor as effluent, and then enters the intermediate sedimentation tank to achieve sludge-water separation. Part of the bottom sludge is returned to the anaerobic tank as return sludge, and the other part is discharged as excess sludge. A first return pipeline is provided between the intermediate sedimentation tank and the anaerobic tank. A peristaltic pump is installed on the first return pipeline. The return ratio of the bottom sludge of the intermediate sedimentation tank to the anaerobic tank is R1=100%. The supernatant is effluent and sequentially enters the post-anoxic tank and aeration tank, and then enters the final sedimentation tank to achieve sludge-water separation. The supernatant from the final sedimentation tank flows out as the final effluent. Part of the bottom sludge from the final sedimentation tank is returned to the first aerobic tank as return sludge, and the other part is discharged as excess sludge. A second return pipeline is provided between the final sedimentation tank and the first aerobic tank. A peristaltic pump is installed on the second return pipeline. The return ratio of the bottom sludge from the final sedimentation tank to the first aerobic tank is 100%. Meanwhile, the anaerobic tank is connected to the first microaerobic PN / A integrated reactor via bypass pipe I. When bypass pipe I is open, the anaerobic tank is not connected to the first aerobic tank. The first microaerobic PN / A integrated reactor is connected to the first post-anoxic tank via bypass pipe II. When bypass pipe II is open, neither the first nor the second microaerobic PN / A integrated reactor is connected to the intermediate sedimentation tank. When the water quality parameters are within the specified concentration range, bypass pipes I and II are in the open state.

2. The device for enhanced deep denitrification of urban wastewater based on SDR-AOA process as described in claim 1, characterized in that, The specified concentration range is COD < 100 mg / L, NH4 < 100 mg / L. + -N < 30 mg / L.

3. The device for enhanced deep denitrification of urban wastewater based on SDR-AOA process as described in claim 1 or 2, characterized in that, The volume ratio of the anaerobic zone, anoxic zone, and aerobic zone is 1:4:

3. The anoxic zone includes the first micro-aerobic PN / A integrated reactor, the second micro-aerobic PN / A integrated reactor, the first post-anoxic tank, and the second post-anoxic tank. The aerobic zone includes the first aerobic tank, the second aerobic tank, and the aeration tank.

4. The device for enhanced deep denitrification of urban wastewater based on SDR-AOA process as described in claim 1, characterized in that, The anaerobic tank, the first aerobic tank, the second aerobic tank, the first microaerobic PN / A integrated reaction tank, and the second microaerobic PN / A integrated reaction tank are connected by water passage holes. The first post-anoxic tank, the second post-anoxic tank, the aeration tank, and the terminal sedimentation tank are connected by water passage holes, and the water passage holes of each reaction tank are arranged in an alternating vertical manner.

5. The device for enhanced deep denitrification of urban wastewater based on SDR-AOA process as described in claim 1, characterized in that, Agitators are installed in the first micro-aerobic PN / A integrated reaction tank, the second micro-aerobic PN / A integrated reaction tank, and the post-anoxic tank; aeration discs are installed at the bottom of the first aerobic tank, the second aerobic tank, the first micro-aerobic PN / A integrated reaction tank, the second micro-aerobic PN / A integrated reaction tank, and the aeration tank, and aeration is carried out by blowers.

6. A method for enhancing deep nitrogen removal from urban wastewater based on the SDR-AOA process, characterized in that, The method using the apparatus as described in any one of claims 1-5 is as follows: Raw water enters the anaerobic tank for ammoniation and phosphorus release reaction, and then enters the aerobic tank. At the same time, the return sludge in the intermediate sedimentation tank enters the anaerobic tank. After entering the first and second aerobic tanks, semi-short-cut nitrification and organic matter degradation occur, while the return sludge in the final sedimentation tank enters the first aerobic tank. Then it enters the first micro-aerobic PN / A integrated reactor and the second micro-aerobic PN / A integrated reactor for short-cut nitrification and anaerobic ammonia oxidation reactions; The sludge enters the intermediate sedimentation tank to achieve sludge-water separation. Part of the bottom sludge is returned to the anaerobic tank as return sludge, and the other part is discharged as excess sludge. Then it enters the first post-anoxic tank and the second post-anoxic tank for anaerobic ammonium oxidation reaction; The sludge enters the aeration tank to further degrade the residual ammonia nitrogen in the raw water, and finally enters the final sedimentation tank to achieve sludge-water separation. The supernatant flows out as the final effluent, and part of the bottom sludge is returned to the first aerobic tank as return sludge, while the other part is discharged as excess sludge.

7. The method for enhancing deep nitrogen removal from urban wastewater based on the SDR-AOA process as described in claim 6, characterized in that, When the water quality parameters are within the specified concentration range, open bypass pipe I and bypass pipe II.

8. The method for enhancing deep nitrogen removal from urban wastewater based on the SDR-AOA process as described in claim 6, characterized in that, The sludge concentration range of the integrated microaerobic PN / A reactor is MLSS=1500~2000mg / L, and the sludge concentration range of other reactors is MLSS=3000~5000mg / L.

9. The method for enhancing deep nitrogen removal from urban wastewater based on the SDR-AOA process as described in claim 7 or 8, characterized in that, The dissolved oxygen (DO) concentration in the first and second aerobic tanks is set to a range of 2.0–3.0 mg / L, and the dissolved oxygen (DO) concentration in the terminal aeration tank is set to a range of 3.0–4.0 mg / L; the sludge age (SRT) is 15–20 days; the sludge return ratio from the bottom of the intermediate sedimentation tank to the anaerobic tank is R1 = 100%, and the sludge return ratio from the bottom of the terminal sedimentation tank to the first aerobic tank is R2 = 100%. When bypass pipeline I and bypass pipeline II are opened, the bypass ratio from the anaerobic tank to the first micro-aerobic PN / A integrated reactor is r1=50%, and the bypass ratio from the first micro-aerobic PN / A integrated reactor to the first post-anoxic tank is r2=50%.

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