Five-stage BioDopp biochemical reaction system and wastewater treatment method

Abstract

This invention relates to the field of wastewater biochemical treatment technology, providing a five-stage BioDopp biochemical reaction system and wastewater treatment method. The five-stage BioDopp biochemical reaction system includes at least one anaerobic zone, at least one primary anoxic zone, at least one primary aerobic zone, at least one secondary anoxic zone, at least one secondary aerobic zone, and at least one three-phase separator. The three-phase separator is located in the last secondary aerobic zone and is positioned at the top near the end. The integrated tank structure saves floor space and elevation loss, facilitates the use of a high-efficiency recirculation device, reduces recirculation energy consumption, and significantly improves the reactor's deep nitrogen and phosphorus removal efficiency. The three-phase separator automatically returns the separated nitrified sludge to the end of the secondary aerobic zone, and then recirculates it to the primary aerobic zone to participate in the biochemical reaction. This simplifies operation, facilitates maintenance and management, and reduces operating energy consumption.

Description

Technical Field

[0001] This invention relates to the field of wastewater biochemical treatment technology, and in particular to a five-stage BioDopp biochemical system and wastewater treatment method. Background Technology

[0002] Wastewater from industries such as coking, pharmaceuticals, fertilizers, and aquaculture contains high concentrations of ammonia nitrogen. High-ammonia nitrogen wastewater is also generated in daily life, such as wastewater from highway service areas.

[0003] Traditional Level A N In the O-type denitrification process, the mixed liquor recirculation ratio is generally controlled between 100% and 400%, and the sludge recirculation ratio is generally controlled between 50% and 100%. Therefore, theoretically, the maximum removal rate of Kjeldahl nitrogen and total nitrogen is 83.3%. However, in actual operation, due to other complex factors, the total nitrogen removal rate often fails to reach the theoretical maximum value. Therefore, if the Kjeldahl nitrogen and total nitrogen in the influent exceed 100 mg / L, it is generally considered that the process is not satisfactory after passing through stage A. N It is difficult for the O denitrification process to meet the Class A emission requirements of the "Urban Wastewater Treatment Plant Pollutant Discharge Standard" to reduce total nitrogen to below 15 mg / L.

[0004] Therefore, in practical engineering applications, when a Kjeldahl nitrogen removal rate of over 90% or a lower total nitrogen effluent is required, the Bardenpho biological process with two-stage AO (Anaerobic / Oxygen Filtration) or a combination of single-stage AO and denitrification filters is generally considered reliable. The former requires a larger site area, and its single-stage nitrification / denitrification removal rate is limited by the reflux ratio, thus limiting its total nitrogen removal rate and resulting in limited nitrogen and phosphorus removal. The latter not only increases construction investment but also increases the difficulty of operation and maintenance management. Summary of the Invention

[0005] This invention provides a five-stage BioDopp biological treatment system and wastewater treatment method to address the shortcomings of existing technologies in achieving standard nitrogen and phosphorus removal effects during the treatment of wastewater with high ammonia nitrogen and high total nitrogen.

[0006] This invention provides a five-stage BioDopp biochemical reaction system, comprising:

[0007] At least one anaerobic zone, the first end of which is provided with an inlet pipe suitable for connecting to sewage;

[0008] At least one primary anoxic zone, the first end of which is provided with a first outflow outlet; the first outflow outlet is adapted to communicate with the anaerobic zone, and the end of the primary anoxic zone is provided with a first flow channel, and a first reflux device is provided in the first flow channel.

[0009] At least one primary aerobic zone, the first end of which is connected to the top of the first flow channel, and the end of which is connected to the second return channel through a second outflow outlet, and one end of the second return channel is connected to the first end of the primary anoxic zone.

[0010] At least one secondary anoxic zone, the first end of which is connected to the other end of the second reflux channel, a first reflux channel is provided in the secondary anoxic zone, and a second reflux device and a third outflow outlet are provided at the end of the secondary anoxic zone. The second reflux device is located at the end of the secondary anoxic zone and is connected to the first reflux channel. The output port of the first reflux channel is connected to the first end of the anaerobic zone.

[0011] At least one secondary aerobic zone, the first end of which is connected to the end of the secondary anoxic zone through the third outflow outlet, the end of which is provided with a third reflux channel, the third reflux channel being adapted to connect the end of the secondary aerobic zone with the first end of the primary aerobic zone, and a third reflux device being provided in the third reflux channel;

[0012] At least one three-phase separator is disposed at the top near the end of the secondary aerobic zone;

[0013] The three-phase separator includes:

[0014] The mud-water separation chamber has at least one water collection tank and at least one water outlet channel at its top. The end of the water outlet channel is connected to a water outlet pipe. The bottom of the mud-water separation chamber has a main gas collection hood and branch gas collection hoods. Multiple branch gas collection hoods are arranged in an alternating manner and stacked to form a gas collection structure. The cross-section of each branch gas collection hood is an inverted "V" shape, and gaps are formed between adjacent branch gas collection hoods. These gaps are connected to the secondary aerobic zone. The top of the main gas collection hood is connected to one end of an exhaust pipe, and the other end of the exhaust pipe is connected to the primary aerobic zone and / or the secondary aerobic zone.

[0015] According to the five-stage BioDopp biochemical reaction system provided by the present invention, both the primary anoxic zone and the secondary anoxic unit are provided with flow guide walls, which are used to extend the average flow path of the mixture.

[0016] According to the five-stage BioDopp biochemical reaction system provided by the present invention, the middle part of the mud-water separation chamber is provided with a combined packing material for mud-water separation and a cleaning device for cleaning the combined packing material.

[0017] According to the five-stage BioDopp biochemical reaction system provided by the present invention, the end of the secondary aerobic zone is connected to a sludge discharge pipe for discharging excess sludge.

[0018] According to the five-stage BioDopp biochemical reaction system provided by the present invention, the end of the primary aerobic zone is provided with a DO monitoring element and / or an ORP monitoring element for online monitoring.

[0019] According to the five-segment BioDopp biochemical reaction system provided by the present invention, the horizontal inclination angle of the triangular inclined plate of the gas collection hood is greater than or equal to 45 degrees, the horizontal spacing between adjacent gas collection hoods in the same layer is greater than or equal to 80 mm, the horizontal overlap spacing between the edges of adjacent gas collection hoods in two layers is greater than or equal to 80 mm, and the width of the narrowest channel of the formed gap is greater than or equal to 80 mm.

[0020] Another aspect of the present invention provides a wastewater treatment method based on a five-stage BioDopp biochemical reaction system according to any one of the above claims, comprising:

[0021] Wastewater is introduced into the anaerobic zone, where the high-quality carbon source in the wastewater is fully mixed with the secondary denitrification sludge mixture that is returned to the anaerobic zone from the end of the secondary anoxic zone, and an anaerobic phosphorus release reaction occurs to obtain an anaerobic phosphorus release sludge mixture.

[0022] The anaerobic phosphorus-releasing sludge mixture enters the first end of the primary anoxic zone and mixes with a portion of the primary nitrifying sludge mixture returned from the end of the primary aerobic zone, and undergoes denitrification and dephosphorization reactions to obtain a primary denitrifying sludge mixture.

[0023] The primary denitrifying sludge mixture enters the primary aerobic zone under the push of the first reflux device to undergo aerobic phosphorus uptake, aerobic carbon removal and nitrification reactions, and obtains primary nitrifying sludge mixture.

[0024] A portion of the primary nitrifying sludge mixture enters the primary anoxic zone for circulation, while another portion enters the secondary anoxic zone, where, under the condition of a carbon source, a further denitrification reaction occurs to obtain a secondary denitrifying sludge mixture.

[0025] A portion of the secondary denitrification sludge mixture is circulated in the anaerobic zone under the drive of the second reflux device, while another portion of the secondary denitrification sludge mixture enters the secondary aerobic zone to undergo further aerobic biochemical reactions, resulting in a secondary aerobic sludge mixture.

[0026] A portion of the secondary aerobic sludge mixture enters a three-phase separator for gas, liquid, and solid separation. The separated clear water flows out, while the separated secondary aerobic sludge enters the secondary aerobic zone. At the end of the secondary aerobic zone, a portion of the secondary aerobic sludge is discharged, while the remaining portion is returned to the beginning of the primary aerobic zone for circulation under the impetus of a third reflux device.

[0027] According to the wastewater treatment method based on the five-stage BioDopp biochemical reaction system provided by the present invention, the sludge concentration at the end of the secondary aerobic zone is controlled between 3 g / L and 10 g / L.

[0028] According to the wastewater treatment method based on a five-stage BioDopp biochemical reaction system provided by the present invention, the DO at the end of the primary aerobic zone is ≤1.0 mg / L and / or ORP is ≤+100.0 mV.

[0029] According to the wastewater treatment method based on a five-stage BioDopp biochemical reaction system provided by the present invention, the recirculation ratio from the primary aerobic zone to the primary anoxic zone is greater than or equal to 300%, the recirculation ratio from the secondary anoxic zone to the anaerobic zone is less than or equal to 200%, and the recirculation ratio from the secondary aerobic zone to the primary aerobic zone is greater than or equal to 100%.

[0030] According to any of the above embodiments, the present invention has at least the following beneficial effects:

[0031] This invention provides a five-stage BioDopp biological treatment system. First, it employs a series process of primary nitrification-denitrification followed by secondary denitrification to remove Kjeldahl nitrogen. The primary nitrification-denitrification process utilizes BioDopp's low dissolved oxygen and high reflux ratio technology and control strategy, which significantly improves the Kjeldahl nitrogen removal rate of the primary nitrification-denitrification process. The secondary denitrification process uses a low reflux ratio, which is closer to the pollutant removal mechanism of a plug flow reactor, making the efficiency of the secondary denitrification process relatively higher. Therefore, it can further improve the Kjeldahl nitrogen removal rate of existing BioDopp biological treatment reactors.

[0032] Secondly, the return sludge in the anaerobic zone comes from the secondary denitrification sludge mixed liquor, which can effectively reduce the impact of nitrate nitrogen and dissolved oxygen in the return mixed liquor on anaerobic phosphorus release. Because the combined concentration of nitrate nitrogen and dissolved oxygen in the secondary denitrification sludge mixed liquor is the lowest, this scheme has a better technical route and solution for removing total phosphorus when the influent Kjeldahl nitrogen is high.

[0033] Finally, a three-phase separator was used to replace the existing mud-water partition. On the one hand, this can reduce the use of mechanical equipment such as sludge suction machines, sludge scrapers, or suction-scraper machines, saving investment, reducing operating costs, reducing mechanical equipment failures, and facilitating operation and maintenance management. On the other hand, the use of a three-phase separator can make more efficient use of the existing tank volume. The bottom of the three-phase separator can still be used as an aerobic zone, increasing the aerobic biochemical reaction time, which is conducive to increasing the treated water volume or saving floor space. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the five-stage BioDopp biochemical reaction system provided in the first embodiment of the present invention;

[0036] Figure 2 This is an AA cross-sectional view of the five-stage BioDopp biochemical reaction system provided in the first embodiment of the present invention;

[0037] Figure 3 This is a BB cross-sectional view of the five-stage BioDopp biochemical reaction system provided in the first embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the five-stage BioDopp biochemical reaction system provided in the second embodiment of the present invention;

[0039] Figure 5 This is a CC cross-sectional view of the five-stage BioDopp biochemical reaction system provided in the second embodiment of the present invention;

[0040] Figure 6 This is a DD cross-sectional view of the five-stage BioDopp biochemical reaction system provided in the second embodiment of the present invention;

[0041] Figure 7 This is a schematic diagram of the five-stage BioDopp biochemical reaction system provided in the third embodiment of the present invention;

[0042] Figure 8 This is an EE cross-sectional view of the five-stage BioDopp biochemical reaction system provided in the third embodiment of the present invention;

[0043] Figure 9 This is an FF cross-sectional view of the five-stage BioDopp biochemical reaction system provided in the third embodiment of the present invention;

[0044] Figure 10 This is another embodiment of the three-phase separator provided by the present invention;

[0045] Figure 11 This is a flowchart of a wastewater treatment method based on a five-stage BioDopp biochemical reaction system provided in the second aspect embodiment of the present invention.

[0046] Figure label:

[0047] 1. Anaerobic zone; 10. Inlet pipe; 11. First baffle; 110. Anaerobic mixing zone;

[0048] 2. Primary anoxic zone; 21. First guide wall; 22. First outlet; 230. First flow channel;

[0049] 3. Primary aerobic zone; 31. First reflux device; 32. DO monitoring element; 33. ORP monitoring element; 34. Second outlet; 324. Second reflux channel;

[0050] 4. Secondary anoxic zone; 41. Second reflux device; 42. Second guide wall; 43. Third outlet; 410. First reflux channel;

[0051] 5. Secondary aerobic zone; 51. Third reflux device; 501. Sludge discharge pipe; 530. Second flow channel; 531. Third reflux channel;

[0052] 6. Three-phase separator; 61. Water collection tank; 62. Water outlet channel; 63. Support vent hood; 64. Main vent hood; 65. Combined packing; 600. Mud-water separation chamber; 601. Water outlet pipeline; 602. Exhaust pipeline. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0054] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0055] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0056] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0057] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0058] With increasing environmental protection requirements and growing demands for ecological environment, higher requirements have been placed on the water quality of various types of wastewater, among which the total nitrogen content in various types of wastewater is one of the key indicators.

[0059] Related water treatment solutions, such as the two-stage AO Bardenpho biological process, require a large site, which limits their application scenarios. Furthermore, the low total nitrogen removal rate of the primary nitrification and denitrification reactions in the two-stage AO Bardenpho biological process restricts the overall improvement of total nitrogen removal efficiency. In related technologies, a combined process such as primary AO plus a denitrification filter can be used to achieve a total nitrogen removal rate of 90%. However, this approach increases the number of devices, raises system construction costs, and increases the difficulty of operation and maintenance management.

[0060] Regarding the problems in related technologies, such as Figures 1-9 As shown, this invention provides a five-stage BioDopp biochemical reaction system, comprising at least one anaerobic zone 1, at least one primary anoxic zone 2, at least one primary aerobic zone 3, at least one secondary anoxic zone 4, at least one secondary aerobic zone 5, and at least one three-phase separator 6. The number of anaerobic zones 1, primary anoxic zones 2, primary aerobic zones 3, secondary anoxic zones 4, secondary aerobic zones 5, and three-phase separator 6 can be adjusted according to design requirements.

[0061] It should be noted that in this invention, the anaerobic zone 1, primary anoxic zone 2, primary aerobic zone 3, secondary anoxic zone 4, and secondary aerobic zone 5 all include a beginning and an end. Within each treatment zone, wastewater or mixed liquor flows from the beginning to the end. For example, in anaerobic zone 1, wastewater enters from the beginning and eventually flows to the end. Between adjacent treatment zones with a sequential processing order, the end of the previous treatment zone is connected to the beginning of the next treatment zone. For example, the end of anaerobic zone 1 is connected to the beginning of primary anoxic zone 2, allowing the mixed liquor to enter from anaerobic zone 1 into primary anoxic zone 2. That is, under the process defined in this invention, the direction of wastewater or mixed liquor flow within each treatment zone is determined, such as... Figure 1 The direction indicated by the middle arrow.

[0062] The first end of the anaerobic zone 1 is equipped with an inlet pipe 10 suitable for connecting sewage. The inlet pipe 10 can introduce sewage into the first end of the anaerobic zone 1, and the sewage undergoes reaction treatment in the anaerobic rich zone so that the mixed liquid after reaction can be introduced into the next process.

[0063] In the specific setup, a first baffle 11 is installed in the anaerobic zone 1. The first baffle 11 is located near the beginning of the anaerobic rich zone and forms an anaerobic fully mixed zone 110. The anaerobic fully mixed zone 110 is also connected to the secondary anoxic zone 4 through a first return channel 410. The secondary denitrification sludge mixture is introduced through the first return channel 410, so that the sewage introduced through the influent pipe 10 can be fully mixed with the secondary denitrification sludge mixture in the anaerobic fully mixed zone 110 and undergo an anaerobic phosphorus release reaction to obtain an anaerobic phosphorus-releasing sludge mixture. The return of the secondary denitrification sludge mixture maintains the average sludge concentration in the anaerobic zone 1, which is beneficial to improving the treatment efficiency of the reaction system.

[0064] In specific applications, some embodiments may provide water passage holes at the bottom of the first partition 11. In other embodiments, the top of the first partition 11 may be set below the flow level, so that the mixed liquid flows through the top of the first partition 11 and the mixed liquid in the anaerobic mixing zone 110 flows toward the end through the water passage at the bottom and finally flows out through the end of the anaerobic zone 1.

[0065] It is understandable that an anaerobic phosphorus release reaction occurs simultaneously with the mixing of wastewater and secondary denitrification sludge mixed liquor, resulting in an anaerobic phosphorus release sludge mixed liquor, which flows from the beginning to the end of anaerobic zone 1.

[0066] In a specific example, a mixing device is installed at the beginning of anaerobic zone 1 to mix the wastewater with the secondary denitrification sludge mixture. In a preferred example, a hyperboloid mixer and / or anaerobic agitation are used.

[0067] The first end of the primary anoxic zone 2 is provided with a first outflow port 22, which is adapted to connect with the anaerobic zone 1. The end of the primary anoxic zone 2 is provided with a first flow channel 230, and a first return device 31 is provided in the first flow channel 230. The anaerobic phosphorus-releasing sludge mixture flows from the end of the anaerobic zone 1 to the beginning of the primary anoxic zone 2 through the first outflow port 22. The anaerobic phosphorus-releasing sludge mixture mixes with a portion of the primary nitrifying sludge mixture returned from the primary aerobic zone 3, and then undergoes denitrification and dephosphorization reactions to obtain a primary denitrifying sludge mixture.

[0068] In a specific configuration, a first flow channel 230 is provided at the end of the first-stage anoxic zone 2. At least one first reflux device 31 is provided within the first flow channel 230, enabling communication between the two treatment zones. Specifically, a flow hole communicating with the first-stage anoxic zone 2 is provided at the bottom of the first flow channel 230, and another flow hole communicating with the first-stage aerobic zone 3 is provided at the top of the first flow channel 230. The first reflux device 31 is located within the first flow channel 230, allowing the mixed liquid to enter from the bottom of the first flow channel 230 and exit from the top under the drive of the first reflux device 31, thereby achieving communication between the first-stage anoxic zone 2 and the first-stage aerobic zone 3.

[0069] In a specific example, three air-lift reflux devices are arranged side by side in the first flow channel 230. The three air-lift reflux devices can drive the flow of the mixed liquid to achieve efficient and rapid circulation of the internal circulation path of the system and improve the processing efficiency.

[0070] The first end of the primary aerobic zone 3 is connected to the top of the first flow channel 230, and the end of the primary aerobic zone 3 is connected to the second return channel 324 through the second outflow port 34. One end of the second return channel 324 is connected to the first end of the primary anoxic zone 2. The primary denitrifying sludge mixture obtained in the primary anoxic zone 2 enters the primary aerobic zone 3 through the first flow channel 230, where it undergoes aerobic phosphorus uptake, aerobic carbon removal, and nitrification reactions to obtain the primary nitrifying sludge mixture. The second return channel 324 has two output ends and one input end. The input end of the second return channel 324 is connected to the end of the primary aerobic zone 3, one output end of the second return channel 324 is connected to the primary anoxic zone 2, and the other output end of the second return channel 324 is connected to the secondary anoxic zone 4. This allows the primary nitrifying sludge mixture to enter different treatment zones for treatment and circulation through the second return channel 324.

[0071] Understandably, a portion of the primary nitrification sludge mixture is returned to the primary anoxic zone 2 to mix with the anaerobic phosphorus-releasing sludge mixture for circulation, while the other portion of the primary nitrification sludge mixture enters the secondary anoxic zone 4 for the next stage of reaction.

[0072] In the specific configuration, a third reflux channel 531 is provided within the primary aerobic zone 3. One end of the third reflux channel 531 is connected to the end of the secondary aerobic zone 5, and the other end of the third reflux channel 531 is located near the beginning of the primary aerobic zone 3 to achieve the reflux of secondary aerobic sludge. The reflux of secondary aerobic sludge can further improve the treatment efficiency and reduce the energy consumption in the treatment cycle.

[0073] The first end of the secondary anoxic zone 4 is connected to the other end of the second reflux channel 324. A first reflux channel 410 is installed within the secondary anoxic zone 4, and a second reflux device 41 and a third outlet 43 are installed at the end of the secondary anoxic zone 4. The second reflux device 41 is connected to the first reflux channel 410, and the outlet of the first reflux channel 410 is connected to the first end of the anaerobic zone 1. A portion of the primary nitrifying sludge mixture enters the secondary anoxic zone 4 through the second reflux channel 324. Under the condition of a carbon source, further denitrification occurs, yielding a secondary denitrifying sludge mixture. The secondary denitrifying sludge mixture flows from the first end to the end of the secondary anoxic zone 4 and is ultimately distributed at the end of the secondary anoxic zone 4.

[0074] Understandably, the presence of a second reflux device 41 and a third outlet 43 at the end of the secondary anoxic zone 4 allows the secondary denitrification sludge mixture to be divided into two parts for flow treatment. One part of the secondary denitrification sludge mixture is driven into the first reflux channel 410 via the second reflux device 41, and then enters the anaerobic mixing zone 110. The anaerobic mixing zone 110 facilitates the mixing of the incoming wastewater with the secondary denitrification sludge mixture, forming a cycle. The other part of the secondary denitrification sludge mixture connects to the secondary aerobic zone 5 via the third outlet 43, where it undergoes further treatment.

[0075] In the specific setup, mixing devices are installed in both the secondary anoxic zone 4 and the primary anoxic zone 2. These mixing devices can effectively mix the liquid, improve the mixing efficiency, and thus achieve efficient wastewater treatment.

[0076] The first end of the secondary aerobic zone 5 is connected to the end of the secondary anoxic zone 4 via a third outflow port 43. A second flow channel 530 is provided at the end of the secondary aerobic zone 5. The bottom of the second flow channel 530 is connected to the secondary aerobic zone 5, and the top of the second flow channel 530 is connected to a third return channel 531. The third return channel 531 ultimately connects the end of the secondary aerobic zone 5 to the first end of the primary aerobic zone 3. A third return device 51 is installed within the second flow channel 530. A portion of the secondary denitrification sludge mixture enters the secondary aerobic zone 5 for further aerobic biochemical reactions, yielding a secondary aerobic sludge mixture. The secondary aerobic sludge mixture enters the three-phase separator 6 for gas, liquid and solid separation. The separated clear water flows out, and the separated secondary aerobic sludge enters the secondary aerobic zone 5. At the end of the secondary aerobic zone 5, a portion of the secondary aerobic sludge is discharged through the pipeline, while the other portion of the secondary aerobic sludge is returned to the beginning of the primary aerobic zone 3 for circulation under the impetus of the third reflux device 51.

[0077] In specific applications, the first reflux device 31, the second reflux device 41, and the third reflux device 51 are at least one of an airlift reflux device or an axial flow pump.

[0078] The three-phase separator 6 is located at the top near the end of the secondary aerobic zone 5. The three-phase separator 6 includes a mud-water separation chamber. The top of the mud-water separation chamber is provided with at least one water collection tank 61 and at least one water outlet channel 62. The end of the water outlet channel 62 is connected to the water outlet pipe. The bottom of the mud-water separation chamber is provided with a main gas collection hood 64 and a branch gas collection hood 63. Multiple branch gas collection hoods 63 are arranged in an alternating manner and stacked to form a gas collection structure. The cross-section of the branch gas collection hood 63 is an inverted "V" shape, and gaps are formed between adjacent branch gas collection hoods 63. The gaps are connected to the secondary aerobic zone 5. The top of the main gas collection hood 64 is connected to one end of the exhaust pipe 602. The other end of the exhaust pipe 602 is connected to the primary aerobic zone 3 and / or the secondary aerobic zone 5.

[0079] When the secondary aerobic sludge mixture flows through the three-phase separator 6, part of it is separated by the separator, while the other part is directly returned to the primary aerobic zone 3 under the drive of the third reflux device 51. During the separation process in the three-phase separator 6, the clear water that has undergone gas collection and sedimentation is first collected through the top water collection tank 61 and then discharged through the effluent pipe. The separated gas is transported to the primary aerobic zone 3 and / or the secondary aerobic zone 5 for reuse through the exhaust pipe. The separated secondary aerobic sludge slides down into the secondary aerobic zone 5 and collects at the end of the secondary aerobic zone 5. Part of the aerobic sludge collected at the end of the secondary aerobic zone 5 enters the primary aerobic zone 3 to participate in sludge circulation, while the other part is discharged through the pipe.

[0080] In a specific configuration, the main body of the three-phase separator 6 is connected to the secondary aerobic zone 5 via a plate structure, forming a mud-water separation chamber. The bottom of the mud-water separation chamber is connected to a main gas collecting hood 64 and multiple branch gas collecting hoods 63. The gas collecting hoods allow for separation of the mixed liquid as it flows through the three-phase separator 6. In a specific example, such as… Figure 2 , Figure 5 and Figure 8 As shown, the bottom of the mud-water separation chamber has an inwardly sloping surface. The sloping surface structure allows the sludge to fall quickly after mud-water separation and enables the falling sludge to be guided and collected.

[0081] Specific examples, such as Figure 2 , Figure 5 and Figure 8 As shown, the main body of the exhaust pipe is located inside the sludge-water separation chamber. The gas inlet end of the exhaust pipe is one end of the main gas collection hood 64, and the end of the exhaust pipe is connected to the primary aerobic zone 3 and / or the secondary aerobic zone 5 to achieve gas reuse. The gas collection hood 63 has a trough-shaped structure with a cross-section that is roughly an inverted "V" shape. This structure facilitates gas separation and sludge sliding.

[0082] Specific examples, such as Figure 8 As shown, a combined packing material 65 for sludge-water separation and a cleaning device for cleaning the combined packing material 65 are arranged in the middle of the sludge-water separation chamber. The combined packing material 65 can be used for sludge-water separation of secondary aerobic sludge mixture in the sludge-water separation chamber. The arrangement of the combined packing material 65 can improve the separation efficiency. The cleaning device can clean the combined packing material 65 to prevent the pores from being blocked during long-term separation. Specifically, the combined packing material 65 can be a porous tube or inclined plate, etc. The cleaning components can be a clean water spray head and / or perforated pipe aeration. The clean water spray head is connected to a high-pressure water pump, and the high-pressure water pump drives clean water to spray through the spray head to clear the blockage. Alternatively, the perforated pipe is connected to a blower, and the flow formed by aeration cleans the packing material.

[0083] Understandably, the cleaning components can be installed either above or below the packing material, with different placement options depending on the cleaning method. For example, a perforated pipe installed at the bottom of the packing material, connected to a blower, can enable cleaning of the packing material.

[0084] In specific configuration, the gas collection hoods 63 can be inverted "V" shaped groove structures of the same specifications. These gas collection hoods 63 of the same specifications are arranged in a staggered, multi-layered manner, such as... Figure 2 , Figure 5 and Figure 8 As shown. Of course, the gas collection hood can also be an inverted "V" shaped groove structure of different specifications, such as... Figure 10 As shown, the first layer adopts a larger inverted "V" shaped groove structure, and the second layer adopts a smaller inverted "V" shaped groove structure. The gas collection hood of the second layer is set between the gas collection hoods of the first layer to form a gas collection structure.

[0085] In specific applications, a sludge discharge pipe 501 is connected to the end of the secondary aerobic zone 5. The sludge discharge pipe 501 is used to discharge excess secondary aerobic sludge from the secondary aerobic zone 5.

[0086] Understandably, when the mixed liquor is separated by the three-phase separator 6, the secondary aerobic sludge mixed liquor flows upward from the bottom of the sludge-water separation chamber. During the flow of the mixed liquor, gas and secondary aerobic sludge are separated. Specifically, the gas is introduced into the primary aerobic zone 3 and / or the secondary aerobic zone 5 through the exhaust pipe, while the secondary aerobic sludge settles and collects at the end of the secondary aerobic zone 5. The separated clear water is discharged through the effluent pipe. Using the three-phase separator 6 to replace the existing sludge-water partition reduces the need for mechanical equipment such as sludge suction machines, sludge scrapers, or suction-scraper machines, saving investment, reducing operating costs, minimizing equipment failures, and facilitating operation and maintenance. Furthermore, the three-phase separator 6 allows for more efficient use of the existing tank volume, as the bottom of the three-phase separator 6 can still be used as an aerobic zone, increasing the aerobic biological reaction time and potentially increasing the treated water volume or saving floor space.

[0087] like Figures 1-3 As shown, the working process of a specific embodiment is as follows:

[0088] Wastewater is introduced into the anaerobic mixing zone 110 through the inlet pipe 10 and thoroughly mixed with the secondary denitrification sludge, undergoing an anaerobic phosphorus release reaction to obtain an anaerobic phosphorus-releasing sludge mixed liquor. Within the anaerobic mixing zone 110, a stirring and mixing device can be used to achieve thorough mixing of the wastewater and the secondary denitrification sludge, improving mixing efficiency.

[0089] The anaerobic phosphorus-releasing sludge mixed liquor enters the primary anoxic zone 2 through the first outflow port 22 and mixes with the primary nitrifying sludge mixed liquor, undergoing denitrification and dephosphorization reactions to obtain the primary denitrifying sludge mixed liquor. A stirring and mixing device can also be installed in the primary anoxic zone 2 to improve the uniformity and mixing efficiency of the mixed liquor.

[0090] The primary denitrification sludge mixture enters the primary aerobic unit through the first flow channel 230. During the flow in the first flow channel 230, it is driven by the first return device 31 to introduce the primary denitrification sludge mixture into the primary aerobic zone 3. In the primary aerobic zone 3, aerobic phosphorus uptake, aerobic carbon removal and nitrification reactions occur to obtain the primary nitrification sludge mixture.

[0091] A portion of the primary nitrifying sludge mixture is returned to the beginning of the primary anoxic zone 2 via the second return channel 324 for circulation, while the other portion enters the secondary anoxic zone 4, where, under the presence of a carbon source, further denitrification occurs to obtain the secondary denitrifying sludge mixture. The second return channel 324 has water passages at both ends, allowing the primary nitrifying sludge mixture entering the second return channel 324 to be processed in different treatment zones through these passages, achieving rapid circulation.

[0092] In the secondary anoxic zone 4, a portion of the secondary denitrification sludge mixture is propelled into the anaerobic zone 1 by the second reflux device 41 for circulation, while the other portion enters the secondary aerobic zone 5 through the third outlet 43 for further aerobic biochemical reactions, yielding a secondary aerobic sludge mixture. The second reflux device 41 is connected to the first reflux channel 410, allowing the secondary denitrification sludge mixture to circulate back to the anaerobic zone 1 via the first reflux channel 410.

[0093] A portion of the secondary aerobic sludge mixture enters the three-phase separator 6 for gas, liquid, and solid separation. The separated clean water flows out through the effluent pipe, while the separated secondary aerobic sludge enters the secondary aerobic zone 5. At the end of the secondary aerobic zone 5, a portion of the secondary aerobic sludge is discharged through the sludge discharge pipe 501, while the other portion of the secondary aerobic sludge, along with the secondary aerobic sludge mixture, is returned to the beginning of the primary aerobic zone 3 for circulation under the impetus of the third reflux device 51.

[0094] As can be seen from the above embodiments, this embodiment, compared with the related BioDopp bioreactor, shows that:

[0095] Firstly, a series process of primary nitrification-denitrification followed by secondary denitrification is used to remove Kjeldahl nitrogen. The primary nitrification-denitrification process adopts the existing BioDopp technology concept and control strategy of low dissolved oxygen and high reflux ratio, which can greatly improve the Kjeldahl nitrogen removal rate of primary nitrification-denitrification. The secondary denitrification uses a low reflux ratio, which is closer to the pollutant removal mechanism of a plug flow reactor, making the efficiency of secondary denitrification relatively higher. Therefore, it can further improve the Kjeldahl nitrogen removal rate of the existing BioDopp bioreactor.

[0096] Secondly, the return sludge in anaerobic zone 1 comes from the secondary denitrification sludge mixed liquor, which can effectively reduce the impact of nitrate nitrogen and dissolved oxygen in the return mixed liquor on anaerobic phosphorus release. Because the combined concentration of nitrate nitrogen and dissolved oxygen in the secondary denitrification sludge mixed liquor is the lowest, this scheme has a better technical route and solution for removing total phosphorus when the influent Kjeldahl nitrogen is high.

[0097] Finally, the three-phase separator 6 was used to replace the existing mud-water partition. On the one hand, this can reduce the use of mechanical equipment such as sludge suction machine, sludge scraper, or suction-scraper, saving investment, reducing operating costs, reducing mechanical equipment failures, and facilitating operation and maintenance management. On the other hand, the three-phase separator 6 can make more efficient use of the existing tank volume. The bottom of the three-phase separator 6 can still be used as an aerobic zone, increasing the aerobic biochemical reaction time, which is conducive to increasing the treated water volume or saving floor space.

[0098] Compared to existing Bardenpho bioreactors:

[0099] Firstly, replacing the traditional external secondary sedimentation tank with a three-phase separator allows for an integrated tank structure, making the wastewater treatment plant layout more compact and saving space. The integrated tank structure also reduces the need for elevation settings in the process flow, even eliminating the need for significant elevation differences between functional zones. This facilitates the widespread use of more efficient recirculation devices such as air-lift recirculation devices and axial flow pumps, thus reducing recirculation energy consumption.

[0100] Secondly, by employing a highly efficient reflux method, it is easy to achieve a higher reflux ratio in the primary nitrification-denitrification reaction process, that is, it is easy to achieve a primary mixed liquor reflux ratio of 400% that is required in the traditional Bardenpho process under relatively low energy consumption conditions. A high reflux ratio can significantly improve the total nitrogen removal rate of primary nitrification-denitrification, thereby enhancing the overall nitrogen removal effect of the process; on the other hand, a high reflux ratio can effectively improve the shock resistance of the primary nitrification-denitrification zone.

[0101] Secondly, from the perspective of the activated sludge circulation path, the three-phase separator 6 does not require a separate sludge return device to return the sludge separated from the external secondary sedimentation tank to the anoxic or anaerobic zone 1. The three-phase separator 6 can automatically return the separated secondary aerobic sludge to the end of the secondary aerobic zone 5, and then return it to the primary aerobic zone 3 along with the secondary aerobic sludge mixture to participate in the biochemical reaction. The advantages of this return method are that, on the one hand, it can save on the construction of sludge return facilities, saving investment; on the other hand, there is no need to worry about the impact of the high dissolved oxygen return from the secondary aerobic zone 5 on the denitrification of the primary anoxic zone 2 and the secondary anoxic zone 4, and even if the dissolved oxygen is high, it can be reused in the primary aerobic zone 3; in addition, this sludge return method is also conducive to greatly increasing the average sludge concentration of the entire reactor, further saving the footprint.

[0102] Finally, by controlling the low dissolved oxygen concentration at the end of the primary aerobic zone 3, the adverse effects of high reflux rates from primary nitrification and denitrification on the anoxic zone can be effectively mitigated. Simultaneously, the dissolved oxygen carried by the primary nitrification sludge mixture entering the secondary anoxic zone 4 can be effectively reduced, thus lowering the carbon source consumption for denitrification in the secondary anoxic zone 4, improving its denitrification efficiency, and also helping to reduce sludge production. Furthermore, the secondary aerobic zone 5 effectively prevents underutilized carbon sources from secondary denitrification from entering the effluent, thus preventing carbon source breakthrough.

[0103] According to one embodiment provided by the present invention, such as Figure 7-9As shown, both the primary anoxic zone 2 and the secondary anoxic unit are equipped with flow guide walls to extend the average flow path of the mixed liquor. These walls divide the treatment area into multiple flow zones, requiring the mixed liquor within each zone to flow around them. This extends the flow path of the mixed liquor within a limited space, promoting denitrification and dephosphorization reactions, and improving the efficiency of biological nitrogen and phosphorus removal.

[0104] In specific settings, such as Figure 7 As shown, the flow guide wall is composed of multiple plate structures, which divide their respective treatment zones into multiple flow units. When the mixed liquid flows from the beginning to the end of its respective treatment zone, the flow path is increased by the plates, thereby promoting the occurrence of denitrification and dephosphorization reactions and improving the biological denitrification and decarbonization effects.

[0105] In other embodiments, such as Figure 4 As shown, the guide walls consist of straight, plate-like wall structures. These guide walls are positioned within their respective treatment zones, extending the flow path of the mixed liquid within each zone. It is understood that the arrangement of the guide walls is not specifically limited, as long as it extends the water flow path within the treatment zone.

[0106] According to one embodiment of the present invention, the end of the primary aerobic zone 3 is provided with a DO monitoring element 32 (Dissolved Oxygen) and / or an ORP monitoring element 33 (Oxidation-Reduction Potential) for online monitoring.

[0107] Understandably, the dissolved oxygen content at the end of the primary aerobic zone 3 can be fed back in real time through the online monitoring in the dissolved oxygen monitoring unit and the oxidation-reduction potential monitoring unit. This allows for monitoring of the wastewater treatment process and adjustment of the aeration rate based on the relevant monitoring results to achieve the best wastewater treatment effect.

[0108] According to one embodiment of the present invention, the horizontal inclination angle of the triangular inclined plate of the gas collecting hood 63 is greater than or equal to 45 degrees, the horizontal spacing between adjacent gas collecting hoods 63 in the same layer is greater than or equal to 80 mm, the horizontal overlap spacing between the edges of adjacent gas collecting hoods 63 is greater than or equal to 80 mm, and the width of the narrowest part of the formed gap is greater than or equal to 80 mm. With the above arrangement, air bubbles can be prevented from escaping to the sedimentation and water collection unit above, thereby avoiding affecting the sedimentation effect and causing a deterioration in the effluent quality.

[0109] like Figure 11 As shown, a second aspect of the present invention provides a wastewater treatment method for the five-stage BioDopp biochemical reaction system provided in any of the above embodiments, comprising:

[0110] S200. Wastewater is introduced into anaerobic zone 1. The high-quality carbon source in the wastewater is fully mixed with the secondary denitrification sludge mixture that is returned to anaerobic zone 1 from the end of the secondary anoxic zone 4, and an anaerobic phosphorus release reaction occurs to obtain anaerobic phosphorus release sludge mixture.

[0111] S210 and anaerobic phosphorus-releasing sludge mixed liquor enter the first end of the first-stage anoxic zone 2 and mix with a portion of the first-stage nitrifying sludge mixed liquor returned from the end of the first-stage aerobic zone 3. Denitrification and dephosphorization reactions and denitrification and decarbonization reactions occur to obtain the first-stage denitrifying sludge mixed liquor.

[0112] S220 and the primary denitrification sludge mixture enter the primary aerobic zone 3 under the push of the first reflux device 31 to undergo aerobic phosphorus uptake, aerobic carbon removal and nitrification reactions, and obtain the primary nitrification sludge mixture.

[0113] S230. A portion of the primary nitrification sludge mixture enters the primary anoxic zone 2 for circulation, while the other portion enters the secondary anoxic zone 4. Under the condition of having a carbon source, a further denitrification reaction occurs to obtain the secondary denitrification sludge mixture.

[0114] S240. A portion of the secondary denitrification sludge mixture enters the anaerobic zone 1 for circulation under the push of the second reflux device 41, while another portion of the secondary denitrification sludge mixture enters the secondary aerobic zone 5 to undergo further aerobic biochemical reactions, resulting in a secondary aerobic sludge mixture.

[0115] S250. A portion of the secondary aerobic sludge mixture enters the three-phase separator 6 for gas, liquid and solid separation. The separated clear water flows out, and the separated secondary aerobic sludge enters the secondary aerobic zone 5. At the end of the secondary aerobic zone 5, a portion of the secondary aerobic sludge is discharged, and the other portion of the secondary aerobic sludge is returned to the beginning of the primary aerobic zone 3 for circulation under the push of the third reflux device 51.

[0116] According to the embodiments provided by the present invention, the sludge concentration at the end of the secondary aerobic zone 5 is controlled between 3 g / L and 10 g / L. Under high sludge concentration conditions, the aeration air volume is controlled by a low dissolved oxygen control strategy. The control method is reliable, and the low dissolved oxygen control strategy helps to improve the oxygenation efficiency of the aeration device and saves operating energy consumption.

[0117] According to the embodiments provided by the present invention, the DO at the end of the primary aerobic zone 3 is ≤1.0 mg / L and / or ORP ≤+100.0 mV. This embodiment enables online monitoring of dissolved oxygen by setting up dissolved oxygen monitoring elements and oxidation-reduction potential monitoring elements. This monitoring allows for real-time adjustment of the aeration airflow, facilitating energy-saving control of the entire biochemical system.

[0118] According to the embodiments provided by the present invention, the recirculation ratio of the primary aerobic zone 3 to the primary anoxic zone 2 is greater than or equal to 300%, the recirculation ratio of the secondary anoxic zone 4 to the anaerobic zone 1 is less than or equal to 200%, and the recirculation ratio of the secondary aerobic zone to the primary aerobic zone is greater than or equal to 100%. By employing a highly efficient recirculation method, it is easy to achieve a higher recirculation ratio in the primary nitrification-denitrification reaction process, that is, it is easy to achieve a primary mixed liquor recirculation ratio of 400% under conditions that would otherwise require a surge in energy consumption compared to the traditional Bardenpho process. A high recirculation ratio can significantly improve the total nitrogen removal rate of the primary nitrification-denitrification process, thereby improving the overall nitrogen removal effect; furthermore, a high recirculation ratio can effectively improve the shock resistance of the primary nitrification-denitrification zone.

[0119] In summary, the five-stage BioDopp biochemical reaction system and wastewater treatment method provided by the embodiments of the present invention have at least the following advantages:

[0120] 1. It retains the integrated structure, which is simple and not only saves space but also reduces the elevation loss of the reactor, which is conducive to energy-saving design. For example, it can greatly reduce the lifting height of the two-stage nitrification sludge mixed liquor recirculation, saving long-term operating energy consumption.

[0121] 2. By adopting a series process of primary nitrification-denitrification + secondary denitrification for the removal of Kjeldahl nitrogen, the removal rate of Kjeldahl nitrogen can be stably maintained at over 90%, or even lower total nitrogen levels can be obtained in the effluent.

[0122] 3. The return sludge in anaerobic zone 1 comes from the secondary denitrification sludge mixed liquor, which can effectively reduce the impact of nitrate nitrogen and dissolved oxygen in the return mixed liquor on anaerobic phosphorus release, improve the biological phosphorus removal efficiency of the biochemical reaction system, and make full use of the carbon source in the raw sewage to achieve denitrification phosphorus removal, thus achieving the effect of "one carbon for two uses".

[0123] 4. The use of the three-phase separator 6 simplifies the operation and management of traditional secondary sedimentation tanks. On the one hand, it eliminates the need for the sludge suction scraper required for secondary sedimentation, reducing the number of operation and management units. On the other hand, it also eliminates the need for independent sludge return facilities, saving investment and operating energy consumption.

[0124] 5. The use of a three-phase separator 6 can further increase the volume of the existing tank for use as a biological reaction zone, increase the biological reaction time, and help increase the amount of water treated and save floor space;

[0125] 6. The primary nitrification sludge mixed liquor recirculation adopts air-lift recirculation instead of traditional mechanical water pump recirculation, which can achieve a large recirculation ratio condition for primary nitrification and denitrification reactions with low energy consumption. Combined with the use of three-phase separator 6, it can greatly increase the average sludge concentration in the reactor, improve the treatment efficiency per unit tank volume, thereby further saving land and reducing construction costs.

[0126] 7. In the primary nitrification-denitrification reaction zone, under the premise of high reflux ratio and high sludge concentration, the adoption of low dissolved oxygen and / or redox potential control strategy is conducive to improving the utilization rate of dissolved oxygen, thereby helping to reduce the operating energy consumption of the reactor, and at the same time greatly improving the shock resistance of the primary reaction zone.

[0127] 8. In the primary nitrification-denitrification reaction zone, under the environment created by the large reflux ratio, high sludge concentration, and low dissolved oxygen, the removal rate of Kjeldahl nitrogen and total nitrogen in the primary nitrification-denitrification reaction zone can be further improved.

[0128] 9. The low dissolved oxygen and / or redox potential control strategy adopted in the primary nitrification and denitrification reaction zone is beneficial to increasing the nitrogen removal ratio of simultaneous nitrification and denitrification and short-cut nitrification and denitrification in the primary aerobic zone 3, which is beneficial to saving energy consumption and carbon source consumption, and also beneficial to reducing sludge production in the primary reaction zone.

[0129] 10. The low dissolved oxygen and / or redox potential control strategy adopted in the primary nitrification-denitrification reaction zone provides better reaction conditions for denitrification in the secondary anoxic zone 4, which is conducive to saving carbon source consumption in secondary denitrification, saving operating costs, and reducing sludge production in the secondary reaction zone.

[0130] 11. The three-phase separator 6 returns the secondary aerobic sludge along the flow path to the secondary aerobic zone 5, and then returns it to the primary aerobic zone 3 along with the secondary aerobic sludge mixture for recycling reaction. There is no need to worry about the impact of the high dissolved oxygen return from the secondary aerobic zone 5 on the denitrification of the primary anoxic zone 2 and the secondary anoxic zone 4. Even if the dissolved oxygen is too high, it can be reused in the primary aerobic zone 3, which is convenient for control and saves operating energy consumption.

[0131] 12. The setting of the secondary aerobic zone 5 can effectively prevent the carbon source that is not fully utilized in the secondary denitrification from entering the effluent and causing carbon source breakthrough.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A five-stage BioDopp biochemical reaction system, characterized in that, include: At least one anaerobic zone, the first end of which is provided with an inlet pipe suitable for connecting to sewage; At least one primary anoxic zone, the first end of which is provided with a first outflow outlet; the first outflow outlet is adapted to communicate with the anaerobic zone, and the end of the primary anoxic zone is provided with a first flow channel, and a first reflux device is provided in the first flow channel. At least one primary aerobic zone, the first end of which is connected to the top of the first flow channel, and the end of which is connected to the second return channel through a second outflow outlet, and one end of the second return channel is connected to the first end of the primary anoxic zone. At least one secondary anoxic zone, the first end of which is connected to the other end of the second reflux channel, a first reflux channel is provided in the secondary anoxic zone, and a second reflux device and a third outflow outlet are provided at the end of the secondary anoxic zone. The second reflux device is located at the end of the secondary anoxic zone and is connected to the first reflux channel. The output port of the first reflux channel is connected to the first end of the anaerobic zone. At least one secondary aerobic zone, the first end of which is connected to the end of the secondary anoxic zone through the third outflow outlet, the end of which is provided with a third reflux channel, the third reflux channel being adapted to connect the end of the secondary aerobic zone with the first end of the primary aerobic zone, and a third reflux device being provided in the third reflux channel; At least one three-phase separator is disposed at the top near the end of the secondary aerobic zone; The three-phase separator includes: The mud-water separation chamber has at least one water collection tank and at least one water outlet channel at its top. The end of the water outlet channel is connected to a water outlet pipe. The bottom of the mud-water separation chamber has a main gas collection hood and branch gas collection hoods. Multiple branch gas collection hoods are arranged in an alternating manner and stacked to form a gas collection structure. The cross-section of each branch gas collection hood is an inverted "V" shape, and gaps are formed between adjacent branch gas collection hoods. These gaps are connected to the secondary aerobic zone. The top of the main gas collection hood is connected to one end of an exhaust pipe, and the other end of the exhaust pipe is connected to the primary aerobic zone and / or the secondary aerobic zone.

2. The five-stage BioDopp biochemical reaction system according to claim 1, characterized in that, Both the primary anoxic zone and the secondary anoxic zone are equipped with flow guide walls, which are used to extend the average flow path of the mixture.

3. The five-stage BioDopp biochemical reaction system according to claim 1, characterized in that, The mud-water separation chamber is provided with a combination packing material for mud-water separation and a cleaning device for cleaning the combination packing material in the middle.

4. The five-stage BioDopp biochemical reaction system according to claim 1, characterized in that, The end of the secondary aerobic zone is connected to a sludge discharge pipe for discharging excess sludge.

5. The five-stage BioDopp biochemical reaction system according to claim 1, characterized in that, The end of the primary aerobic zone is equipped with a DO monitoring element and / or an ORP monitoring element for online monitoring.

6. The five-stage BioDopp biochemical reaction system according to claim 1, characterized in that, The horizontal inclination angle of the triangular inclined plate of the gas collection hood is greater than or equal to 45 degrees, the horizontal spacing between adjacent gas collection hoods on the same layer is greater than or equal to 80 mm, the horizontal overlap spacing between the edges of adjacent gas collection hoods on two layers is greater than or equal to 80 mm, and the width of the narrowest channel of the formed gap is greater than or equal to 80 mm.

7. A wastewater treatment method based on the five-stage BioDopp biochemical reaction system according to any one of claims 1 to 6, characterized in that, include: Wastewater is introduced into the anaerobic zone, where the high-quality carbon source in the wastewater is fully mixed with the secondary denitrification sludge mixture that is returned to the anaerobic zone from the end of the secondary anoxic zone, and an anaerobic phosphorus release reaction occurs to obtain an anaerobic phosphorus release sludge mixture. The anaerobic phosphorus-releasing sludge mixture enters the first end of the primary anoxic zone and mixes with a portion of the primary nitrifying sludge mixture returned from the end of the primary aerobic zone, and undergoes denitrification and dephosphorization reactions to obtain a primary denitrifying sludge mixture. The primary denitrifying sludge mixture enters the primary aerobic zone under the push of the first reflux device to undergo aerobic phosphorus uptake, aerobic carbon removal and nitrification reactions, and obtains primary nitrifying sludge mixture. A portion of the primary nitrifying sludge mixture enters the primary anoxic zone for circulation, while another portion enters the secondary anoxic zone, where, under the condition of a carbon source, a further denitrification reaction occurs to obtain a secondary denitrifying sludge mixture. A portion of the secondary denitrification sludge mixture is circulated in the anaerobic zone under the drive of the second reflux device, while another portion of the secondary denitrification sludge mixture enters the secondary aerobic zone to undergo further aerobic biochemical reactions, resulting in a secondary aerobic sludge mixture. A portion of the secondary aerobic sludge mixture enters a three-phase separator for gas, liquid, and solid separation. The separated clear water flows out, while the separated secondary aerobic sludge enters the secondary aerobic zone. At the end of the secondary aerobic zone, a portion of the secondary aerobic sludge is discharged, while the remaining portion is returned to the beginning of the primary aerobic zone for circulation under the impetus of a third reflux device.

8. The wastewater treatment method of the five-stage BioDopp biochemical reaction system according to claim 7, characterized in that, The sludge concentration at the end of the secondary aerobic zone is controlled between 3 g / L and 10 g / L.

9. The wastewater treatment method of the five-stage BioDopp biochemical reaction system according to claim 7, characterized in that, The DO at the end of the primary aerobic zone is ≤1.0 mg / L and / or ORP is ≤+100.0 mV.

10. The wastewater treatment method of the five-stage BioDopp biochemical reaction system according to claim 7, characterized in that, The recirculation ratio from the primary aerobic zone to the primary anoxic zone is greater than or equal to 300%, the recirculation ratio from the secondary anoxic zone to the anaerobic zone is less than or equal to 200%, and the recirculation ratio from the secondary aerobic zone to the primary aerobic zone is greater than or equal to 100%.

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