Device and method for deep nitrogen removal from wastewater based on IFAS-PNAD continuous flow system

Abstract

This invention discloses a device and method for deep denitrification of wastewater based on an IFAS-PNAD continuous flow system. An anaerobic tank, an aerobic tank, an anoxic tank, and a micro-aerobic tank are sequentially connected. Raw water enters the sedimentation tank via the inlet of the anaerobic tank and the effluent from the micro-aerobic tank. The supernatant flows out of the sedimentation tank, and part of the bottom sludge is returned to the anaerobic tank, while the other part enters a sludge anaerobic fermentation system. The fermentation broth produced by the sludge anaerobic fermentation system enters a sludge side-treatment device. This sludge side-treatment device is connected to both the aerobic and anoxic tanks, and a portion of the activated sludge from the anaerobic tank is transported to the sludge side-treatment device. The micro-aerobic tank is connected to the anoxic tank via a nitrification liquor return system, and the anaerobic tank is connected to the anoxic tank via a bypass pipeline system. A controller controls the opening, closing, and switching of the bypass pipeline system, the nitrification liquor return system, and the output of the sludge side-treatment device, as well as the flow rate regulation of the sludge anaerobic fermentation system. This invention can achieve a combination of various operating environments, effectively improving denitrification efficiency.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a device and method for achieving deep denitrification of wastewater based on an IFAS-PNAD continuous flow system. Background Technology

[0002] Patent application CN116605991A discloses a device and method for rapidly improving the deep denitrification of high ammonia nitrogen wastewater based on a PNA continuous flow IFAS process. This solution addresses the problems of existing wastewater treatment plants, such as low influent C / N ratios, the need for external carbon sources, and high operating costs due to aeration energy consumption. It fully analyzes the advantages and disadvantages of existing wastewater treatment processes and proposes a highly efficient and low-consumption wastewater treatment process and system. Through different effluent methods and macroscopic dynamic control, it effectively alters the microbial community state, reduces the need for external carbon source addition, and improves autotrophic denitrification performance. Once mature, this technology can achieve direct treatment of high ammonia nitrogen wastewater without dilution, facilitating operation and management. However, this solution has the following main problems:

[0003] 1. Currently, new wastewater treatment processes are effective for 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 a relatively limited range of influent water qualities. Since the water quality of urban wastewater fluctuates with regional and seasonal changes, they cannot achieve universal applicability and are difficult to further promote for future engineering applications.

[0004] 2. The operation of the integrated PNA process system is completed in an aerobic environment. Since there is no nitrite accumulation process, the system is conducive to the stable maintenance of the short-cut nitrification process. However, since anaerobic ammonia oxidizing bacteria are extremely sensitive to dissolved oxygen concentration, when the dissolved oxygen concentration is too high during operation, it will have an irreversible impact on the activity of anaerobic ammonia oxidizing bacteria. Conversely, maintaining a low dissolved oxygen concentration will reduce the impact on the activity of anaerobic ammonia oxidizing bacteria, but it will also weaken the activity of nitrifying bacteria to a certain extent, resulting in insufficient nitrite accumulation and affecting the anaerobic ammonia oxidation process.

[0005] 3. Although the MBR treatment technology currently in use has high solid-liquid separation efficiency and good removal effect on suspended solids, most pollutants in municipal sewage can be removed by biological treatment processes. For sewage with good influent quality, the use of MBR will undoubtedly increase the treatment cost. In addition, the accumulation of recalcitrant organic matter can easily cause membrane fouling, which can cause great damage to the membrane itself. Therefore, the aeration energy consumption of MBR system is high, and the later operation and maintenance costs are also high. Summary of the Invention

[0006] In view of this, the present invention provides a device and method for deep denitrification of wastewater based on the IFAS-PNAD continuous flow system, which can realize a combination of various operating environments and effectively improve denitrification efficiency.

[0007] The technical solution adopted in this invention is as follows:

[0008] A device for deep denitrification of wastewater based on an IFAS-PNAD continuous flow system is characterized by comprising an anaerobic tank, an aerobic tank, an anoxic tank, a micro-aerobic tank, a sedimentation tank, a controller, an bypass pipeline system, a sludge side-by-side treatment device, a nitrification liquor return system, and a sludge anaerobic fermentation system.

[0009] The anaerobic tank, aerobic tank, anoxic tank, and microaerobic tank are connected in sequence. A polyurethane sponge packing frame is installed in the anoxic tank. Raw water enters the sedimentation tank through the anaerobic tank inlet and the microaerobic tank effluent to achieve sludge-water separation. The supernatant in the sedimentation tank is discharged as the final effluent, and part of the bottom sludge is returned to the anaerobic tank as recycled sludge, while the other part enters the sludge anaerobic fermentation system. The fermentation liquid produced by the sludge anaerobic fermentation system enters the sludge side treatment device. The sludge side treatment device is connected to the aerobic tank and the anoxic tank through pipelines to inhibit the activity of nitrite-oxidizing bacteria in the activated sludge. At the same time, part of the activated sludge from the anaerobic tank is transported to the sludge side treatment device through pipelines.

[0010] The micro-aerobic tank is connected to the anoxic tank through a nitrification liquid return system, and the anaerobic tank is connected to the anoxic tank through a bypass pipeline system. When the bypass pipeline system is open, the anaerobic tank and the aerobic tank are not connected.

[0011] The controller monitors water quality and quantity to control the opening, closing, and switching of the bypass pipeline system, nitrification liquor return system, and sludge side treatment device output, as well as the flow regulation of the sludge anaerobic fermentation system.

[0012] This invention also provides a method for deep denitrification of wastewater based on an IFAS-PNAD continuous flow system, using the aforementioned apparatus, and the method is as follows:

[0013] Raw water enters the anaerobic tank for ammoniation and phosphorus release reactions before entering the aerobic tank; at the same time, the returned sludge in the sedimentation tank enters the anaerobic tank; part of the activated sludge in the anaerobic tank is transported to the sludge side treatment device.

[0014] After entering the aerobic tank, nitrification and organic matter degradation occur, and then the solution enters the anoxic tank for anaerobic ammonia oxidation. Under the control of the controller, the nitrified liquid in the micro-aerobic tank is returned to the anoxic tank through the nitrified liquid return system for denitrification and nitrogen removal.

[0015] Then it enters the micro-aerobic tank for further nitrification and degradation of organic matter;

[0016] Finally, the sedimentation tank is used to separate the mud and water. The supernatant is used as the final effluent and flows out of the system. Part of the bottom mud is returned to the anaerobic tank as return sludge, and the other part is used as the remaining sludge and enters the anaerobic fermentation system. The sludge fermentation liquid produced by the anaerobic fermentation system enters the sludge side treatment device.

[0017] The activated sludge, after being treated by the sludge side treatment device, carries the sludge fermentation liquid and is used to provide a carbon source for the aerobic or anoxic tank and to inhibit the NOB activity in the activated sludge. The direction of the treated activated sludge to the aerobic or anoxic tank is determined by the selection of the controller and whether the bypass pipeline system is open.

[0018] Beneficial effects:

[0019] 1. This invention, by setting up a bypass pipeline system between the anaerobic and anoxic tanks, enables the switching between various operating modes, such as traditional AAO and multi-stage AO, under different influent water quality conditions. Utilizing macroscopic dynamic control, it effectively alters the microbial community state. Simultaneously, this strategy reduces aeration energy consumption, shortens the treatment process, and improves treatment efficiency without requiring an aerobic tank. This process is applicable to various wastewater treatment scenarios, including those with high ammonia nitrogen and high concentrations of organic matter. Secondly, this invention combines anaerobic ammonia oxidation with short-cut denitrification by setting up a nitrification liquor recirculation system. It fully utilizes the nitrate nitrogen and ammonia nitrogen in the recirculation liquor from the end of the aerobic zone and the microaerobic zone, further removing nitrate nitrogen produced by anaerobic ammonia oxidation while also providing nitrite, a substrate for anaerobic ammonia oxidizing bacteria (Anammox), achieving deep denitrification of wastewater.

[0020] This invention combines short-cut nitrification, short-cut denitrification, and anaerobic ammonium oxidation processes in multiple operating modes (A... 2 With the support of O, multi-stage AO, etc., the biofilm process in the main reaction zone is operated in the activated sludge mode by using a mud-film mixing strategy, ultimately achieving the goal of deep denitrification and synergistic carbon reduction of urban sewage.

[0021] Moreover, the adjustable continuous flow treatment system has a simple process flow and is easy to operate. Due to the introduction of the PLC control platform, the operation mode of each reaction tank can be automatically adjusted according to the water quality requirements of the influent and effluent. The system has good denitrification performance. Under the condition that the influent is domestic sewage, the average total nitrogen removal rate exceeds 90%. This process can provide theoretical reference and technical support for engineering applications.

[0022] 2. During sludge fermentation, the deamination of microorganisms releases a large amount of ammonia nitrogen and organic matter. Directly returning these to the system would impact the microbial community. This process employs a strategy of side-treatment with activated sludge to solve this problem, reduce the influent ammonia nitrogen load, and improve the effluent quality. At the same time, the system can adjust the input of treated sludge according to the influent water quality to maximize the utilization rate of the sludge anaerobic fermentation system.

[0023] 3. This invention utilizes an anaerobic fermentation system for sludge to develop an internal carbon source within the sludge fermentation liquid. This provides a high-quality carbon source for both aerobic and anoxic stages, saving on the addition of external carbon sources while also addressing the subsequent treatment and disposal of excess sludge, thus achieving sludge reduction. By leveraging the characteristic that humic acid in the sludge fermentation liquid can inhibit the activity of nitrite-oxidizing bacteria (NOB), and combining strategies such as short sludge age, low-oxygen aeration, and starvation treatment, it effectively achieves NOB washing and in-situ enrichment of ammonia-oxidizing bacteria (AOB), increasing the nitrite accumulation rate, realizing a stable short-cut nitrification process, and further reducing aeration energy consumption.

[0024] 4. This invention introduces suspended hollow ring packing and polyurethane sponge packing, adopts sludge-film symbiotic IFAS treatment technology, and utilizes the basic principles of biofilm method to fully leverage the advantages of activated sludge method, realizing the operation of biofilm process in activated sludge mode. In addition, a micro-aerobic tank is set at the end of the system to reduce the impact of dissolved oxygen in the returned nitrification liquid on the anoxic tank. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the device of the present invention.

[0026] Figure 2 This is a schematic diagram of a PLC controller circuit.

[0027] Figure 3 This is a flowchart of the PLC controller control method.

[0028] Among them, 1-inlet water, 2-anaerobic tank, 3-first aerobic tank, 4-second aerobic tank, 5-first anoxic tank, 6-second anoxic tank, 7-first micro-aerobic tank, 8-second micro-aerobic tank, 9-sedimentation tank, 10-outlet water, 11-agitator, 12-submersible solenoid valve, 13-hollow ring packing, 14-polyurethane sponge packing frame, 15-water quality and quantity sensor, 16-PLC controller, 17-electromagnetic flow meter, 18-peristaltic pump, 19-aeration disc, 20-blower, 21-sludge side treatment device, 22-sludge fermentation liquid storage tank, 23-centrifuge, 24-sludge fermentation tank. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] This invention provides a device for deep nitrogen removal from wastewater based on an IFAS-PNAD continuous flow system. IFAS (Integrated Fixed-film Activated Sludge) refers to sludge-film symbiosis, and PNAD (Partial Nitrification / Anammox Denitrification) refers to short-cut nitrification + anaerobic ammonium oxidation + short-cut denitrification and denitrification. Figure 1 As shown, the device includes an anaerobic tank 2, a first aerobic tank 3, a second aerobic tank 4, a first anoxic tank 5, a second anoxic tank 6, a first microaerobic tank 7, a second microaerobic tank 8, a sedimentation tank 9, a controller, an bypass pipeline system, a sludge side treatment device 21, a nitrification liquor return system, and a sludge anaerobic fermentation system.

[0031] In this embodiment, the controller is a PLC controller 16. The sludge anaerobic fermentation system includes a sludge fermentation tank 24, a centrifuge 23, and a sludge fermentation liquid storage tank 22. Another portion of the bottom sludge in the sedimentation tank 9, as surplus sludge, undergoes anaerobic alkaline fermentation in the sludge fermentation tank 24, followed by centrifugation 23 to produce sludge fermentation liquid, which is stored in the sludge fermentation liquid storage tank 22. The sludge fermentation liquid contains a large amount of high-quality carbon source. Simultaneously, the humic acid and short-chain fatty acids in it inhibit the activity of nitrite-oxidizing bacteria in activated sludge. The sludge fermentation liquid produced by the anaerobic fermentation system enters the sludge side-treatment device 21.

[0032] Anaerobic tank 2, first aerobic tank 3, second aerobic tank 4, first anoxic tank 5, second anoxic tank 6, first microaerobic tank 7, and second microaerobic tank 8 are sequentially connected through water passages. Polyurethane sponge packing frames 14 are installed in the first anoxic tank 5 and the second anoxic tank 6, while suspended hollow ring packing 13 is installed in the first aerobic tank 3 and the second aerobic tank 4. Raw water enters the sedimentation tank 9 through the inlet of anaerobic tank 2 and the outlet of the second microaerobic tank 8 to achieve sludge-water separation. The supernatant in the sedimentation tank 9 flows out as the final effluent 10. Part of the bottom sludge is returned to anaerobic tank 2 as return sludge, with a peristaltic pump 18 installed on the return pipeline. The other part of the bottom sludge enters the sludge anaerobic fermentation system as residual sludge. The fermentation broth produced by the sludge anaerobic fermentation system enters the sludge side treatment device 21. The sludge side treatment device 21 is connected to the first aerobic tank 3 and the first anoxic tank 5 through pipelines. The pipelines are equipped with peristaltic pumps. The sludge side treatment device 21 is used to inhibit the activity of nitrite oxidizing bacteria in activated sludge. At the same time, part of the activated sludge in the anaerobic tank 2 is transported to the sludge side treatment device 21 through pipelines. The pipelines are also equipped with peristaltic pumps.

[0033] The second microaerobic tank 8 is connected to the first anoxic tank 5 through a nitrification liquid return system, which is used to return the nitrification liquid in the second microaerobic tank 8 to the first anoxic tank 5; the anaerobic tank 2 is connected to the first anoxic tank 5 through a bypass pipeline system, and the anaerobic tank 2 is not connected to the first aerobic tank 3 when the bypass pipeline system is open.

[0034] like Figure 2 , Figure 3 As shown, the PLC controller 16 is connected to the water quality and quantity sensor 15, the bypass pipeline system, the nitrification liquor return system, and the sludge anaerobic fermentation system to monitor water quality and quantity. The water quality and quantity sensor 15 periodically captures influent and parameter data of each reaction zone, transmits them to the PLC controller 16 for processing and storage, and uploads valid data to the cloud database. The PLC controller 16 compares the collected data with the database. When the water quality index parameters are within the specified concentration range, it triggers control and adjustment commands for the bypass pipeline system, the nitrification liquor return system, the sludge side treatment device 21, and the sludge anaerobic fermentation system, and sends them to each subsystem to control the opening, closing, and switching of the output terminals of the bypass pipeline system, the nitrification liquor return system, and the sludge side treatment device 21, and to adjust the flow rate of the sludge anaerobic fermentation system.

[0035] After receiving the instruction from the PLC controller 16, the subsystem will turn on / off the corresponding electromagnetic flow meter 17, submersible solenoid valve 12, peristaltic pump and other equipment to ensure that the system can operate normally and efficiently. At the same time, the electromagnetic flow meter 17 will automatically adjust the start and stop of the aeration system according to the data transmitted by the water quality and quantity sensor 15.

[0036] Specifically, the anaerobic tank 2 is connected to the first anoxic tank 5 via a bypass pipe installed at the bottom, and a submersible solenoid valve 12 is installed between the anaerobic tank 2 and the first aerobic tank 3. When the bypass pipe system is activated, the device switches from normal operation mode to bypass pipe system activated operation mode, the bypass pipe is connected, and the submersible solenoid valve 12 is closed, so that the raw water, after being treated by the anaerobic tank 2, skips the first aerobic tank 3 and the second aerobic tank 4 and directly enters the first anoxic tank 5. In normal operation mode, the volume ratio of the anaerobic zone, anoxic zone, and aerobic zone is 1:2:4. The anaerobic zone is anaerobic tank 2, the anoxic zone includes the first anoxic tank 5 and the second anoxic tank 6, and the aerobic zone includes the first aerobic tank 3, the second aerobic tank 4, the first microaerobic tank 7, and the second microaerobic tank 8. In the operation mode with the bypass pipeline system open, since anaerobic tank 2 is directly connected to the first anoxic tank 5, the volume ratio of the anaerobic zone, anoxic zone, and aerobic zone is 1:2:2. At this time, the anaerobic zone is anaerobic tank 2, the anoxic zone includes the first anoxic tank 5 and the second anoxic tank 6, and the aerobic zone is the first microaerobic tank 7 and the second microaerobic tank 8.

[0037] Agitators 11 are installed in anaerobic tank 2, first anoxic tank 5, and second anoxic tank 6. Aeration systems are installed at the bottom of first aerobic tank 3, second aerobic tank 4, first microaerobic tank 7, and second microaerobic tank 8. The aeration system is controlled by a PLC controller 16 to adjust the aeration rate of each reaction tank. The aeration system includes aeration discs 19, blowers 20, and electromagnetic flow meters 17. Electromagnetic flow meters 17 are installed on the connecting pipes between the blower 20 and each reaction tank. The PLC controller 16 controls the aeration rate of each reaction tank by adjusting the gas flow rate of the blower 20.

[0038] This embodiment also provides a method for deep denitrification of wastewater based on an IFAS-PNAD continuous flow system, using the device for deep denitrification of wastewater based on the IFAS-PNAD continuous flow system described in the above embodiment. The method is as follows:

[0039] The influent 1 first enters the front-end anaerobic tank 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 in the water. Returned sludge from sedimentation tank 9 also enters the anaerobic tank 2 to maintain the sludge concentration in the anaerobic tank 2. Some of the activated sludge in the anaerobic tank 2 is transported to the sludge side treatment device 21 by a peristaltic pump. The residual sludge fermentation liquid after anaerobic fermentation can inhibit the activity of nitrite oxidizing bacteria (NOB) in activated sludge, thereby highlighting the activity of ammonia oxidizing bacteria (AOB), increasing the nitrite accumulation rate in the aerobic section, and enhancing the activity of anaerobic ammonia oxidizing bacteria in the subsequent anoxic tank. At the same time, the introduced sludge fermentation liquid contains a large amount of high-quality carbon sources such as short-chain fatty acids, which can be used for anaerobic and subsequent anoxic processes.

[0040] After entering the first aerobic tank 3 and the second aerobic tank 4, ammonia nitrogen in the water is converted into nitrite nitrogen and nitrate nitrogen by nitrifying bacteria. At the same time, organic matter is utilized and degraded by aerobic heterotrophic bacteria during aerobic aeration. In addition, under the control of PLC controller 16, part of the activated sludge treated by the sludge side treatment device 21 is transported to the first aerobic tank 3 by a peristaltic pump to inhibit NOB activity.

[0041] Then it enters the first anoxic tank 5 and the second anoxic tank 6, where the anaerobic ammonia-oxidizing bacteria in the biofilm on the packing material can utilize NO2. - Oxidized NH4 + This allows both to be removed simultaneously, and the NO3 produced in this process... -Under the action of denitrifying bacteria, the nitrogen will be further converted into N2. Simultaneously, under the control of PLC controller 16, the returned nitrified liquid from the downstream second micro-aerobic tank 8 also enters the first anoxic tank 5. Under anoxic conditions, the denitrifying bacteria reduce nitrate and nitrite nitrogen in the water to N2 and discharge it into the system. When PLC controller 16 activates the bypass pipeline system, the anaerobic tank 2 is directly connected to the first anoxic tank 5, stopping the supply of activated sludge to the first aerobic tank 3. The sludge side-treatment device 21 then begins supplying activated sludge to the first anoxic tank 5.

[0042] Afterwards, the water enters the first microaerobic tank 7 and the second microaerobic tank 8, where nitrifying bacteria further degrade ammonia nitrogen. Residual organic matter in the water is further removed by heterotrophic bacteria. The low-oxygen aeration strategy in this reaction zone can reduce the dissolved oxygen carried in the reflux nitrification liquid, thereby reducing the impact on the activity of key bacterial groups in the anoxic tank.

[0043] Finally, the sedimentation tank 9 is used to separate the mud and water. The supernatant is discharged from the system as the final effluent 10. Part of the bottom mud is returned to the anaerobic tank 2 as return sludge, and the other part is entered into the anaerobic fermentation system as residual sludge. After the anaerobic fermentation process, the latter produces sludge fermentation liquid, which enters the sludge side treatment device 21.

[0044] The activated sludge, after being treated by the sludge side treatment device 21, carries the sludge fermentation liquid. While providing a carbon source for the aerobic or anoxic tank, it can also inhibit the NOB activity in the activated sludge. After the sludge is returned to the system after side treatment, a short-cut nitrification process is further realized.

[0045] The wastewater retention time in each individual reaction tank is 2.5 hours. The average sludge concentration (MLSS) in each reaction tank of the system is 3000-5000 mg / L. Under normal operation mode, the total hydraulic retention time (HRT) of the system is 17.5 hours. Under the operation mode with the bypass pipeline open, the total hydraulic retention time (HRT) of the system is 12.5 hours. The sludge age (SRT) is 15-20 days.

[0046] Under normal circumstances, the influent water quality range of the system is: NH4 + -N is 40.0~60.0mg / L, NO3 - -N is 0~1.0mg / L, NO2 - -N is 0–1.0 mg / L, TN is 50.0–70.0 mg / L, and COD is 150.0–200.0 mg / L; the system effluent water quality range is: NH4 + -N is 0~1.0mg / L, NO3 - -N is 0-0.5 mg / 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] When the water quality and quantity sensor 15 detects that the water quality is good (within the specified concentration range), the influent water quality range is: NH4 + When -N < 30.0 mg / L, TN < 40.0 mg / L, and COD < 100.0 mg / L, the relevant instructions of PLC controller 16 will be triggered, opening the bypass pipe at the bottom of anaerobic tank 2 and closing the submersible solenoid valve 12 between anaerobic tank 2 and the first aerobic tank 3. This allows the raw water, after being treated in anaerobic tank 2, to bypass the first aerobic tank 3 and the second aerobic tank 4 and directly enter the first anoxic tank 5. Simultaneously, the peristaltic pump on the pipeline connecting to the sludge bypass treatment device 21, which delivers water to the first aerobic tank 3, will be turned off, and the peristaltic pump on the pipeline connecting to the sludge bypass treatment device 21, which delivers water to the first anoxic tank 5, will be turned on. Due to the influent NH4+... + The concentration is low, and the NO3 produced by nitrification in the aerobic stage is high. - The nitrification liquor reflux ratio can be reduced by issuing a command to decrease the flow meter opening degree. Operating according to the above method can eliminate the intermediate aerobic tank, reduce system aeration energy consumption, shorten hydraulic retention time, and improve treatment efficiency.

[0048] For the first 30 days before the system officially went into operation, the raw water was artificially prepared. The chemicals and their concentrations (after addition) are shown in the table below:

[0049] Table 1 Concentration of Chemicals Used in Artificial Water Preparation

[0050]

[0051] 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.

[0052] In this embodiment, the aerobic tank uses cylindrical polyethylene hollow ring packing material 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 anoxic tank is equipped with a polyurethane sponge packing frame 14. The sponge packing, inoculated with anaerobic ammonia-oxidizing bacteria, has a filling ratio of 25-30%, a porosity of 90-95%, and a specific surface area of ​​15,000-18,000 m². 2 / m 3The bulk density is 15-20 kg / m³. 3 The dissolved oxygen concentration (DO) in the aerobic tank is 3.0–4.0 mg / L, and the dissolved oxygen concentration (DO) in the microaerobic tank is 0.5–2.0 mg / L. The return ratio (r) of the nitrified liquor from the microaerobic tank to the upstream anoxic tank (internal return) is generally set to 300%, but adjusted to 200% when the influent quality is good. The return ratio (R) of part of the excess sludge from sedimentation tank 9 to the upstream anaerobic tank 2 (external return) is 100%. After treatment by the anaerobic fermentation system, the resulting fermentation liquor treats a portion of the activated sludge transported from anaerobic tank 2 to the sludge side-treatment device 21 for side-treatment. An equal volume of activated sludge is transported to the first aerobic tank 3. When the influent water quality is within the specified concentration range, an equal volume of treated activated sludge is transported to the first anoxic tank 5. The ratio of activated sludge transport flow rate (transport flow rate / influent flow rate) is 50%, meaning that the volume of activated sludge output from anaerobic tank 2 is the same as that transported to the first aerobic tank 3 or the first anoxic tank 5. The internal pH of the anaerobic fermentation system is adjusted by NaOH solution to maintain it within the range of 9.5 to 10.5. A certain amount of fermented sludge is discharged daily according to the fermentation status, and an equal amount of fresh excess activated sludge is input.

[0053] 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 deep denitrification of wastewater based on an IFAS-PNAD continuous flow system, characterized in that, It includes anaerobic tanks, aerobic tanks, anoxic tanks, microaerobic tanks, sedimentation tanks, controllers, bypass pipeline systems, sludge side-by-side treatment devices, nitrification liquor return systems, and sludge anaerobic fermentation systems; The anaerobic tank, aerobic tank, anoxic tank, and microaerobic tank are connected in sequence. A polyurethane sponge packing frame is installed in the anoxic tank. The aerobic tank is used for nitrification and organic matter degradation, and then the wastewater enters the anoxic tank for anaerobic ammonia oxidation and denitrification. The dissolved oxygen concentration (DO) in the microaerobic tank is 0.5~2.0 mg / L. Raw water enters the sedimentation tank through the anaerobic tank inlet and the microaerobic tank effluent to achieve sludge-water separation. The supernatant in the sedimentation tank is discharged as the final effluent, and part of the bottom sludge is returned to the anaerobic tank as recycled sludge, while the other part enters the sludge anaerobic fermentation system. The fermentation broth produced by the sludge anaerobic fermentation system enters the sludge side treatment device. The sludge side treatment device is connected to the aerobic tank and the anoxic tank through pipelines to inhibit the activity of nitrite-oxidizing bacteria in the activated sludge; at the same time, part of the activated sludge from the anaerobic tank is transported to the sludge side treatment device through pipelines. The micro-aerobic tank is connected to the anoxic tank through a nitrification liquid return system, and the anaerobic tank is connected to the anoxic tank through a bypass pipeline system. When the bypass pipeline system is open, the anaerobic tank and the aerobic tank are not connected. The controller monitors water quality and quantity to control the opening, closing, and switching of the bypass pipeline system, nitrification liquor return system, and sludge side treatment device output, as well as the flow regulation of the sludge anaerobic fermentation system.

2. The device for deep denitrification of wastewater based on the IFAS-PNAD continuous flow system as described in claim 1, characterized in that, In normal operation mode, the volume ratio of the anaerobic zone, anoxic zone, and aerobic zone is 1:2:

4. The anaerobic zone is an anaerobic tank, the anoxic zone includes a first anoxic tank and a second anoxic tank, and the aerobic zone includes a first aerobic tank, a second aerobic tank, a first microaerobic tank, and a second microaerobic tank. In operation mode with the bypass pipeline system open, the volume ratio of the anaerobic zone, anoxic zone, and aerobic zone is 1:2:

2. The anaerobic zone is an anaerobic tank, the anoxic zone includes a first anoxic tank and a second anoxic tank, and the aerobic zone includes a first microaerobic tank and a second microaerobic tank.

3. The device for deep denitrification of wastewater based on the IFAS-PNAD continuous flow system as described in claim 2, characterized in that, The anaerobic and anoxic tanks are equipped with stirrers, and the aerobic and microaerobic tanks are equipped with aeration systems. The aeration rate of each reaction tank is adjusted by controlling the aeration system through a controller.

4. The device for deep denitrification of wastewater based on the IFAS-PNAD continuous flow system as described in claim 2 or 3, characterized in that, The aerobic tank contains polyethylene hollow ring packing material with a suspended cylindrical structure.

5. The device for deep denitrification of wastewater based on the IFAS-PNAD continuous flow system as described in claim 4, characterized in that, The sludge anaerobic fermentation system includes a sludge fermentation tank, a centrifuge, and a sludge fermentation liquid storage tank. Another part of the bottom sludge in the sedimentation tank is used as residual sludge. After anaerobic alkaline fermentation in the sludge fermentation tank, it is processed by centrifuge to produce sludge fermentation liquid, which is stored in the sludge fermentation liquid storage tank.

6. A method for deep denitrification of wastewater based on an IFAS-PNAD continuous flow system, characterized in that, The method using the apparatus as described in any one of claims 2-5 is as follows: Raw water enters the anaerobic tank for ammoniation and phosphorus release reactions before entering the aerobic tank; at the same time, the returned sludge in the sedimentation tank enters the anaerobic tank; part of the activated sludge in the anaerobic tank is transported to the sludge side treatment device. After entering the aerobic tank, nitrification and organic matter degradation occur, and then the solution enters the anoxic tank for anaerobic ammonia oxidation. Under the control of the controller, the nitrified liquid in the micro-aerobic tank is returned to the anoxic tank through the nitrified liquid return system for denitrification and nitrogen removal. Then it enters the micro-aerobic tank for further nitrification and degradation of organic matter; Finally, the sedimentation tank is used to separate the mud and water. The supernatant is used as the final effluent and flows out of the system. Part of the bottom mud is returned to the anaerobic tank as return sludge, and the other part is used as the remaining sludge and enters the anaerobic fermentation system. The sludge fermentation liquid produced by the anaerobic fermentation system enters the sludge side treatment device. The activated sludge, after being treated by the sludge side treatment device, carries the sludge fermentation liquid and is used to provide a carbon source for the aerobic or anoxic tank and to inhibit the NOB activity in the activated sludge. The direction of the treated activated sludge to the aerobic or anoxic tank is determined by the selection of the controller and whether the bypass pipeline system is open.

7. The method for deep denitrification of wastewater based on the IFAS-PNAD continuous flow system as described in claim 6, characterized in that, The controller monitors water quality and quantity, compares the collected data with the database, and triggers control commands for the bypass pipeline system, nitrification liquor return system, sludge side treatment device, and sludge anaerobic fermentation system when the water quality index parameters are within the specified concentration range.

8. The method for deep denitrification of wastewater based on the IFAS-PNAD continuous flow system as described in claim 6, characterized in that, When the influent water quality range is: NH4 + When -N < 30.0 mg / L, TN < 40.0 mg / L, and COD < 100.0 mg / L, the controller activates the bypass pipeline system, directly connecting the anaerobic tank to the anoxic tank. Simultaneously, the supply of activated sludge to the first aerobic tank is stopped, and the supply of activated sludge to the first anoxic tank begins.

9. The method for deep denitrification of wastewater based on the IFAS-PNAD continuous flow system as described in any one of claims 6-8, characterized in that, The dissolved oxygen concentration (DO) in the aerobic tank is 3.0~4.0 mg / L, and the dissolved oxygen concentration (DO) in the microaerobic tank is 0.5~2.0 mg / L; the return ratio (r) of the nitrified liquor from the microaerobic tank to the upstream anoxic tank is 300%; the return ratio (R) of part of the excess sludge from the sedimentation tank to the upstream anaerobic tank is 100%. After some of the remaining sludge is treated by the sludge anaerobic fermentation system, the resulting sludge fermentation liquid is used to treat some of the activated sludge transported from the anaerobic tank to the sludge side treatment device. The treated activated sludge is then transported in equal volume to the first aerobic tank. When transferring activated sludge to the first anoxic tank, the volume of activated sludge is the same as that transferred to the anaerobic tank, and the ratio of activated sludge transfer flow rate is 50%. The transfer flow rate ratio refers to the transfer flow rate / influent flow rate. The internal pH of the sludge anaerobic fermentation system is adjusted by NaOH solution to keep it within the range of 9.5 to 10.5.

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