An industrial wastewater internal circulation denitrification treatment system

Abstract

The utility model discloses an industrial wastewater internal circulation denitrification treatment system, its characterized in that, including anaerobic tank, aerobic tank, anoxic tank and sedimentation tank, install the submergence pump in the sedimentation tank, the output of submergence pump is connected with the water pumping pipe, the other end of water pumping pipe is immersed anaerobic tank, and submergence pump can pump from the sedimentation tank to anaerobic tank, the top of aerobic tank is installed with self -priming pump, and the both sides of self -priming pump are equipped with water inlet and water outlet respectively, and the water inlet is connected with the water inlet pipe, and the other end of water inlet pipe is immersed aerobic tank, and the water outlet is connected with the water outlet pipe, and the other end of water outlet pipe is immersed anaerobic tank, and self -priming pump can pump from aerobic tank to anaerobic tank, the water pumping pipe and water inlet pipe are connected through the communication pipe, and the communication pipe is controlled on-off through valve subassembly, the utility model discloses have the front nitrate removal effect, prevent the effect of jam, the long -term stable operation of internal circulation system.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment devices, and more specifically, to an industrial wastewater internal circulation denitrification treatment system. Background Technology

[0002] An industrial wastewater denitrification system is an environmentally friendly treatment device specifically designed to remove nitrogenous pollutants (such as ammonia nitrogen and nitrate nitrogen) from wastewater. Its core process typically follows the "anaerobic-aerobic" biological treatment principle, utilizing a series of multiple treatment tanks to achieve highly efficient denitrification through specific microbial communities. In the aerobic tank, nitrifying bacteria convert ammonia nitrogen into nitrate nitrogen; in the anaerobic tank, denitrifying bacteria reduce nitrate nitrogen to harmless nitrogen gas, which is then released into the atmosphere.

[0003] Existing denitrification systems typically employ a multi-tank continuous treatment approach, where wastewater is sequentially treated through multiple treatment tanks arranged side-by-side to achieve wastewater purification.

[0004] For example, in AOA's improved wastewater treatment technology, wastewater can be recycled through three stages: anaerobic, aerobic, and anoxic, with a sludge return system. First, the wastewater passes through an anaerobic tank to release phosphorus from the organic matter. Then, it passes through an aerobic tank to convert ammonia nitrogen into nitrate nitrogen while absorbing phosphorus. Next, it passes through an anoxic tank to reduce the nitrogen to harmless nitrogen gas, achieving deep denitrification. Finally, the wastewater passes through a sedimentation tank for sedimentation, and the sludge from the sedimentation tank is returned to the anaerobic tank for further treatment via a submersible pump.

[0005] To improve the efficiency of the anaerobic-aerobic two-stage reaction in the treatment process, an additional anaerobic-aerobic step is typically added, and two sets of anaerobic-aerobic reaction tanks are continuously installed to form a treatment cycle of "anaerobic 1 - aerobic 1 - anaerobic 2 - aerobic 2 - anoxic". This enhances the efficiency of the anaerobic-aerobic two-stage reaction and ultimately improves the wastewater treatment effect. However, adding anaerobic-aerobic reaction tanks increases the footprint and number of tanks in the entire treatment system.

[0006] Therefore, a new solution is needed to address this problem. Utility Model Content

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an industrial wastewater internal circulation denitrification treatment system that has a pre-denitrification effect, prevents clogging, and ensures long-term stable operation of the internal circulation system.

[0008] To achieve the above objectives, this utility model adopts the following technical solution: an industrial wastewater internal circulation denitrification treatment system, comprising an anaerobic tank, an aerobic tank, an anoxic tank, and a sedimentation tank. The anaerobic tank and the aerobic tank are separated by a partition plate 1, with a flow channel 1 at the upper end of the partition plate 1. The aerobic tank and the anoxic tank are separated by a partition plate 2, with a flow channel 2 at the upper end of the partition plate 2. The anoxic tank and the sedimentation tank are separated by a partition plate 3, with a flow channel 3 at the upper end of the partition plate 3. The sedimentation tank is equipped with... The system is equipped with a submersible pump, the output end of which is connected to a pumping pipe, the other end of which is immersed in the anaerobic tank. The submersible pump can pump water from the sedimentation tank into the anaerobic tank. A self-priming pump is installed above the aerobic tank. The self-priming pump has an inlet and an outlet on both sides. The inlet is connected to an inlet pipe, the other end of which is immersed in the aerobic tank. The outlet is connected to an outlet pipe, the other end of which is immersed in the anaerobic tank. The self-priming pump can pump water from the aerobic tank into the anaerobic tank.

[0009] By adopting the above scheme, constructing a multi-stage biological treatment unit of "anaerobic-aerobic-anoxic-sedimentation," and designing a dual-circuit internal circulation architecture composed of a submersible pump and a self-priming pump, the technical problem of incomplete nitrogen removal in traditional denitrification processes is effectively solved. Specifically, the self-priming pump returns the nitrate-rich mixed liquor from the aerobic tank to the anaerobic tank, achieving pre-denitrification; simultaneously, the submersible pump returns the concentrated sludge from the sedimentation tank to the front end of the system, maintaining high biomass and achieving deep removal of nitrate nitrogen and sludge recycling through the connection of the connecting pipe and the self-priming pump circuit. This invention is further configured such that the pumping pipe and the inlet pipe are connected by a connecting pipe, which is controlled by a valve assembly.

[0010] By adopting the above technical solution, water pumped by the submersible pump can be delivered to the inlet side of the self-priming pump through the connecting pipe, allowing water to fill the self-priming pump and the inlet pipe, thus enabling the self-priming pump to pump smoothly. Furthermore, the valve assembly installed in the connecting pipe allows the system to flexibly control the internal circulation flow and its on / off state.

[0011] The present invention is further configured such that a first end of the connecting pipe is fixedly connected to a T-connector 1, and the second end of the connecting pipe is connected to a water pumping pipe through the T-connector 1; a second end of the connecting pipe is fixedly connected to a T-connector 2, and the second end of the connecting pipe is connected to a water inlet pipe through the T-connector 2.

[0012] By adopting the above scheme, a compact and reliable "I"-shaped pipeline hub is constructed by fixing a connecting pipe between T-connector 1 and T-connector 2, connecting the pumping pipe of the submersible pump with the inlet pipe of the self-priming pump. This design not only achieves smooth merging and unified transportation of sludge return liquid and nitrification liquid in the internal circulation system, effectively simplifying the pipeline layout, reducing installation complexity and equipment space occupation, but also enhances the system's sealing and integrity through standardized pipe fitting connections, effectively preventing leakage risks.

[0013] The present invention is further configured such that a valve assembly is installed inside the connecting pipe, the valve assembly including a valve stem, a valve block and a retaining ring, the valve stem being slidably installed inside the connecting pipe, the valve block being fixedly installed in the middle of the valve stem, the retaining ring being fixedly connected to the inner side of the connecting pipe, the valve block sliding with the valve stem and cooperating with the retaining ring to open or close the fluid passage.

[0014] By adopting the above scheme, and by installing an integrated valve assembly consisting of a valve stem, a valve block, and a retaining ring inside the connecting pipe, reliable opening, closing, and regulation of the internal circulation channel are achieved. The sliding valve stem drives the valve block to seal against the fixed retaining ring, forming a compact and easy-to-operate direct-flow shut-off function, which can effectively control the backflow of the sedimentation tank mixed liquor to the aerobic tank.

[0015] The present invention is further configured such that the valve block has a sealing conical surface part one on the side facing the retaining ring, and the inner circumference of the retaining ring has a sealing conical surface part two, wherein the sealing conical surface part one and the sealing conical surface part two are adapted to each other.

[0016] By adopting the above scheme, and by setting mutually compatible sealing cone sections one and two on the valve block and retaining ring respectively, a high-performance conical seal is formed. This conical seal design can achieve a tight fit when the valve block is closed, improving the sealing reliability of the valve assembly in the closed state and effectively preventing internal leakage of the mixture.

[0017] The present invention is further configured such that a filter screen is installed inside the connecting pipe, and the filter screen is used to filter impurities in the wastewater.

[0018] By adopting the above solution and integrating a filter screen inside the connecting pipe, suspended solids and particulate impurities carried in the internal circulating mixture can be continuously intercepted and removed, effectively preventing blockage and wear of the pump body, pipelines and subsequent biochemical treatment units caused by the accumulation of impurities.

[0019] The present invention is further configured such that the filter screen is fixedly installed on the valve stem, and the filter screen and the valve block are respectively located on both sides of the retaining ring; the filter screen is located at one end of the connecting pipe near the water pumping pipe.

[0020] By adopting the above solution, the filter screen is fixedly installed on the valve stem, and positioned on both sides of the retaining ring and near the inlet end of the connecting pipe close to the pumping pipe, the filtration and valve control functions are integrated. This structural design allows the axial movement of a single valve stem to synchronously drive the displacement of the filter screen and the opening and closing of the valve block. This not only simplifies the mechanism and saves space, but also ensures that the filter screen is always located at the front end of the fluid, effectively intercepting suspended particles contained in the mixed liquid drawn from the sedimentation tank and preventing impurities from entering subsequent pipelines and the pump body.

[0021] The present invention is further configured such that the valve stem has a first position and a second position during axial movement. In the first position, the valve block and the retaining ring press and seal against each other, the flow channel of the connecting pipe is closed, and the filter screen extends from the end of the connecting pipe. In the second position, the valve block and the retaining ring separate, the flow channel of the connecting pipe is opened, and the filter screen retracts into the connecting pipe.

[0022] By adopting the above scheme and limiting the valve stem to two distinct axial working positions, the linkage function of "shutdown-filtration" and "opening-self-cleaning" is realized. When the valve stem is in the first position, the system closes the flow channel and pushes the filter screen out of the connecting pipe, exposing it to the cavity of the three-way connector. At this time, the incoming flow can effectively backwash the filter screen. When the valve stem is in the second position, the flow channel is opened and the filter screen retracts into the pipe. The system performs normal filtration and backflow, effectively solving the problem of easy clogging in the internal circulation system.

[0023] The present invention is further configured such that a sealing sleeve is fixedly provided at the lower end of the two-way connector, and the valve stem is slidably inserted into the inner hole of the sealing sleeve, and the valve stem and the sealing sleeve slide and seal.

[0024] By adopting the above solution, a sealing sleeve is fixedly installed at the lower end of the tee connector, allowing the valve stem to slide within its inner bore and maintain a dynamic seal, thus providing axial guidance and radial sealing for the valve stem assembly. This design not only effectively prevents leakage of the mixture in the connecting pipe along the valve stem gap, ensuring the stability of system pressure and flow, but also reduces friction and wobbling during valve stem movement.

[0025] The present invention is further configured such that a valve is installed on the pumping pipe, the valve being located on the side of the pumping pipe near the anaerobic tank and downstream of the connecting pipe.

[0026] By adopting the above scheme, a valve is installed on the pumping pipe, downstream of the connecting pipe and close to the anaerobic tank, to control the sludge return path. This design allows operators to independently adjust the sludge return flow between the settling pump and the anaerobic tank without affecting the nitrification liquor return operation of the self-priming pump.

[0027] The present invention is further configured such that corresponding packing modules are installed in the anaerobic tank, the aerobic tank and the anoxic tank, the anaerobic tank is filled with anaerobic packing, the aerobic tank is filled with aerobic packing, and the anoxic tank is filled with anoxic packing.

[0028] By adopting the above scheme, a multi-stage immobilized biofilm system was constructed by filling the anaerobic, aerobic, and anoxic tanks with specialized packing materials. The anaerobic packing material provided a suitable growth carrier for hydrolytic acidifying and denitrifying bacteria, the aerobic packing material enriched with a high concentration of nitrifying bacteria, and the anoxic packing material enhanced the efficiency of the denitrification process. This hierarchical packing material layout improved the retention and activity of microorganisms in each functional unit, forming a composite process of synergistic action between suspended sludge and biofilm. This not only significantly improved the system's nitrogen removal load and treatment efficiency but also enhanced overall operational stability and resistance to shock loads, ensuring long-term stable compliance of effluent quality.

[0029] In summary, this utility model has the following beneficial effects:

[0030] 1. The system uses a self-priming pump to return the nitrified liquid from the aerobic tank to the anaerobic tank, thus achieving pre-denitrification. At the same time, the sludge mixture from the sedimentation tank is combined with the nitrified liquid and returned together by a submersible pump. This not only completes sludge return and maintains the system's biomass, but also achieves deep removal of nitrate nitrogen.

[0031] 2. The valve assembly and filter screen integrated in the connecting pipe realize the linkage control of flow channel opening and closing and impurity filtration. In the closed state, the filter screen can be automatically backwashed to effectively prevent clogging and ensure the long-term stable operation of the internal circulation system. Attached Figure Description

[0032] Figure 1 This is a plan view of an industrial wastewater internal circulation denitrification treatment system in this embodiment;

[0033] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0034] Figure 3 This is a cross-sectional view of the valve stem in the first position in this embodiment.

[0035] Figure labels: Anaerobic tank 1; Baffle 101; Flow channel 102; Aerobic tank 2; Baffle 21; Flow channel 22; Anoxic tank 3; Baffle 31; Flow channel 32; Sedimentation tank 4; Submersible pump 5; Pumping pipe 51; Valve 52; Self-priming pump 6; Inlet 61; Outlet 62; Inlet pipe 63; Outlet pipe 64; Filter module 65; Connecting pipe 7; T-connector 1 701; T-connector 2 702; Valve stem 71; Valve block 72; Sealing cone section 1 73; Filter screen 74; Retaining ring 75; Sealing cone section 2 751; Sealing sleeve 76; Anaerobic packing material 81; Aerobic packing material 82; Anoxic packing material 83. Detailed Implementation

[0036] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0037] This embodiment discloses an industrial wastewater internal circulation denitrification treatment system, referring to... Figures 1-3 As shown, it includes an anaerobic tank 1, an aerobic tank 2, an anoxic tank 3, and a sedimentation tank 4 connected in series. Each of the anaerobic tank 1, aerobic tank 2, and anoxic tank 3 is equipped with a corresponding biological packing module. The anaerobic tank 1 is filled with anaerobic packing 81, the aerobic tank 2 is filled with aerobic packing 82, and the anoxic tank 3 is filled with anoxic packing 83, so as to construct an immobilized biofilm environment that adapts to the growth and metabolic needs of different microbial communities.

[0038] Each treatment unit is separated by partitions and equipped with an upper flow channel to achieve hydraulic connection. Specifically, anaerobic tank 1 and aerobic tank 2 are separated by partition 101, with a flow channel 102 at the upper end of partition 101; aerobic tank 2 and anoxic tank 3 are separated by partition 21, with a flow channel 22 at the upper end of partition 21; and anoxic tank 3 and sedimentation tank are separated by partition 31, with a flow channel 32 at the upper end of partition 31.

[0039] During system operation, wastewater is filtered through a screen to remove large particles and then pumped to anaerobic tank 1 by a lift pump in the equalization tank. The wastewater undergoes hydrolysis, acidification, and phosphorus release reactions, releasing phosphorus from the organic matter in the wastewater through anaerobic processes. Subsequently, it overflows into aerobic tank 2 through channel 102 to undergo nitrification of ammonia nitrogen, converting ammonia nitrogen into nitrate nitrogen and completing the absorption of phosphorus. The nitrified liquid enters anoxic tank 3 through channel 22, where denitrification is completed under anoxic conditions, reducing nitrate nitrogen to harmless nitrogen gas. Finally, the mixed liquid enters sedimentation tank 4 through channel 32, achieving sludge-water separation.

[0040] To achieve deep denitrification and sludge recirculation, this system is equipped with a dual-circulation internal structure. One circuit is for nitrification liquid recirculation. A self-priming pump 6 is installed above the aerobic tank 2. The self-priming pump 6 has an inlet 61 and an outlet 62 on both sides. The inlet 61 is connected to an inlet pipe 63, the other end of which is immersed in the aerobic tank 2. The outlet 62 is connected to an outlet pipe 64, the other end of which is immersed in the anaerobic tank 1. The self-priming pump 6 can pump from the aerobic tank 2 to the anaerobic tank 1. Some of the wastewater in the aerobic tank 2 is drawn out through the inlet pipe 63 and transported to the front end of the anaerobic tank 1 through the outlet pipe 64 for secondary treatment, realizing the pre-denitrification of nitrate nitrogen.

[0041] The other route is sludge return. A submersible pump 5 is installed in the sedimentation tank 4. The output end of the submersible pump 5 is connected to a pumping pipe 51. The other end of the pumping pipe 51 is immersed in the anaerobic tank 1. The submersible pump 5 can pump from the sedimentation tank 4 to the anaerobic tank 1. The concentrated sludge is returned to the anaerobic tank 1 for treatment through the submersible pump 5. Finally, the treated wastewater enters the purification tank in sequence along the flow channel. After purification by adding purification agent, it is discharged after reaching the standard.

[0042] The submersible pump 5 is immersed in the bottom of the sedimentation tank 4, and can smoothly pump water from the bottom of the tank during operation. The self-priming pump 6, however, needs to be filled with water to operate. After standing for a period of time, air may enter the self-priming pump 6, preventing the formation of pumping pressure and hindering circulation. Typically, water needs to be manually added to the self-priming pump 6 to fill its internal cavity before it can operate normally. To maintain the convenience of the self-priming pump 6, a connecting pipe can be installed between the suction pipe 51 and the inlet pipe 63, allowing some of the water pumped by the submersible pump 5 to be introduced into the self-priming pump 6, reducing the need for manual water addition.

[0043] Reference Figure 2 As shown, the pumping pipe 51 and the inlet pipe 63 are connected by a connecting pipe 7. A T-connector 701 is fixedly connected to the first end of the connecting pipe 7, and the second end of the connecting pipe 7 is connected to the pumping pipe 51 via the same T-connector 701. A second T-connector 702 is also fixedly connected to the second end of the connecting pipe 7, and the second end of the connecting pipe 7 is connected to the inlet pipe 63 via the same T-connector 702. The T-connector 701 has three ports, two of which are connected to the pumping pipe 51, and the third port is integrally connected to the first end of the connecting pipe 7, thus connecting the first end of the connecting pipe 7 to the pumping pipe 51 to form a three-way branch.

[0044] A valve assembly is installed inside the connecting pipe 7, and the opening and closing of the connecting pipe 7 is controlled by the valve assembly. The valve assembly includes a valve stem 71, a valve block 72, and a retaining ring 75. The valve stem 71 is partially slidably installed inside the connecting pipe 7, and the valve block 72 is fixedly installed in the middle of the valve stem 71. The retaining ring 75 is fixedly connected to the inner side of the connecting pipe 7. The valve block 72 slides with the valve stem 71 and cooperates with the retaining ring 75 to open or close the fluid passage.

[0045] The valve block 72 has a sealing conical surface 73 on the side facing the retaining ring 75, and a second sealing conical surface 751 on the inner circumference of the retaining ring 75. The first sealing conical surface 73 and the second sealing conical surface 751 are adapted to each other. When the fluid passage is closed, the first sealing conical surface 73 and the second sealing conical surface 751 are tightly fitted together. A valve 52 is installed on the pumping pipe 51. The valve 52 is located on the side of the pumping pipe 51 near the anaerobic tank 1 and downstream of the connecting pipe 7. It can control the on / off state and flow rate of the water in the pumping pipe 51.

[0046] Furthermore, when the submersible pump 5 replenishes water to the self-priming pump 6, some sludge from the bottom will mix in, resulting in a certain amount of muddy water entering the self-priming pump 6, which may affect the normal operation of the self-priming pump. A filter screen 74 is installed inside the connecting pipe 7, which can remove most of the impurities from the muddy water; additionally, a filter module 65 can be installed at the connection between the inlet of the self-priming pump 6 and the inlet pipe to supplement the filtered water.

[0047] Furthermore, the filter screen inside the filter screen 74 can also adopt a movable structure. The filter screen 74 can be fixedly installed on the top of the valve stem 71, and the filter screen 74 and the valve block 72 are respectively located on both sides of the retaining ring 75. The filter screen 74 is located at the end of the connecting pipe 7 near the water pumping pipe 51, and is used to filter impurities in the wastewater.

[0048] Reference Figure 2 , Figure 3 As shown, valve stem 71 has a first position and a second position during axial movement. In the first position, valve block 72 and retaining ring 75 are pressed together and sealed, the flow channel of connecting pipe 7 is closed, and filter screen 74 extends from the end of connecting pipe 7. At this time, valve 52 is opened, and the sedimentation pump in sedimentation tank 4 pumps the settled wastewater into pumping pipe 51 to backwash the filter screen. In the second position, valve block 72 separates from retaining ring 75, the flow channel of connecting pipe 7 is opened, and filter screen 74 retracts into connecting pipe 7, allowing the system to perform normal internal circulation. Wastewater in pumping pipe enters self-priming pump 6 through connecting pipe and fills inlet pipe 63, thus enabling the wastewater in aerobic tank 2 to be pumped to anaerobic tank 1 for secondary treatment.

[0049] By moving the filter screen 74, impurities adhering to its surface can be shaken off to a certain extent, reducing prolonged static deposition. Furthermore, when the filter screen 74 enters the flow channel of the pumping pipe 51, the flow direction of the pipe is roughly parallel to that of the filter screen 74, preventing blockage. Any small amount of sludge adhering to the sides of the filter screen 74 will be filtered and separated by the second filtration module when the filter screen 74 needs to perform its filtration function.

[0050] A sealing sleeve 76 is fixedly installed at the lower end of the tee connector 2 (702). The valve stem 71 can slide through the inner hole of the sealing sleeve 76, and the valve stem 71 maintains a dynamic seal with the sealing sleeve 76 while sliding up and down. By fixing the sealing sleeve 76 at the lower end of the tee connector 2, the valve stem 71 slides in its inner hole and maintains a dynamic seal, providing axial guidance and radial sealing for the valve stem assembly. This design not only effectively prevents leakage of the mixture in the connecting pipe 7 along the valve stem gap, ensuring the stability of system pressure and flow, but also reduces friction and shaking of the valve stem 71 during movement.

[0051] This system significantly improves denitrification efficiency and operational stability through the synergistic effect of multi-stage biochemical treatment and dual-circuit circulation, combined with integrated valve-controlled filtration and self-cleaning functions, achieving efficient deep treatment and resource reuse of industrial wastewater.

[0052] The above description is merely a preferred embodiment of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are protected. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should also be considered within the protection scope of this utility model.

Claims

1. An industrial wastewater internal circulation denitrification treatment system, characterized in that, It includes an anaerobic tank (1), an aerobic tank (2), an anoxic tank (3) and a sedimentation tank (4). The anaerobic tank (1) and the aerobic tank (2) are separated by a partition (101), and a flow channel (102) is provided at the upper end of the partition (101). The aerobic tank (2) and the anoxic tank (3) are separated by a partition (21), and a flow channel (22) is provided at the upper end of the partition (21). The anoxic tank (3) and the sedimentation tank are separated by a partition (31), and a flow channel (32) is provided at the upper end of the partition (31). A submersible pump (5) is installed in the sedimentation tank (4). The output end of the submersible pump (5) is connected to a pumping pipe (51). The other end of the pumping pipe (51) is immersed in the anaerobic tank (1). The submersible pump (5) can pump water from the sedimentation tank (4) to the anaerobic tank (1). A self-priming pump (6) is installed above the aerobic tank (2). The self-priming pump (6) has an inlet (61) and an outlet (62) on both sides. The inlet (61) is connected to an inlet pipe (63), and the other end of the inlet pipe (63) is immersed in the aerobic tank (2). The outlet (62) is connected to an outlet pipe (64), the other end of which is immersed in the anaerobic tank (1). The self-priming pump (6) can pump water from the aerobic tank (2) to the anaerobic tank (1).

2. The industrial wastewater internal circulation denitrification treatment system according to claim 1, characterized in that, The water pumping pipe (51) and the water inlet pipe (63) are connected by a connecting pipe (7), which is controlled by a valve assembly.

3. The industrial wastewater internal circulation denitrification treatment system according to claim 2, characterized in that, The first end of the connecting pipe (7) is fixedly connected to a three-way connector (701), and the second end of the connecting pipe (7) is connected to a water pumping pipe (51) through the three-way connector (701). The second end of the connecting pipe (7) is fixedly connected to a three-way connector (702), and the second end of the connecting pipe (7) is connected to the water inlet pipe (63) through the three-way connector (702).

4. The industrial wastewater internal circulation denitrification treatment system according to claim 3, characterized in that, A valve assembly is installed inside the connecting pipe (7). The valve assembly includes a valve stem (71), a valve block (72), and a retaining ring (75). The valve stem (71) is partially slidably installed inside the connecting pipe (7). The valve block (72) is fixedly installed in the middle of the valve stem (71). The retaining ring (75) is fixedly connected to the inside of the connecting pipe (7). The valve block (72) slides with the valve stem (71) and cooperates with the retaining ring (75) to open or close the fluid passage.

5. The industrial wastewater internal circulation denitrification treatment system according to claim 4, characterized in that, The valve block (72) has a sealing cone surface one (73) on the side facing the retaining ring (75), and the retaining ring (75) has a sealing cone surface two (751) on its inner circumference. The sealing cone surface one (73) and the sealing cone surface two (751) are adapted to each other.

6. The industrial wastewater internal circulation denitrification treatment system according to claim 4, characterized in that, The connecting pipe (7) is equipped with a filter screen (74) for filtering impurities in the wastewater.

7. The industrial wastewater internal circulation denitrification treatment system according to claim 6, characterized in that, The filter screen (74) is fixedly installed on the valve stem (71), and the filter screen (74) and the valve block (72) are located on both sides of the retaining ring (75); the filter screen (74) is located at one end of the connecting pipe (7) near the water pumping pipe (51).

8. The industrial wastewater internal circulation denitrification treatment system according to claim 7, characterized in that, The valve stem (71) has a first position and a second position during axial movement. In the first position, the valve block (72) and the retaining ring (75) press against each other to seal, the flow channel of the connecting pipe (7) is closed, and the filter screen (74) extends out from the end of the connecting pipe (7). In the second position, the valve block (72) and the retaining ring (75) separate, the flow channel of the connecting pipe (7) is opened, and the filter screen (74) retracts into the connecting pipe (7).

9. The industrial wastewater internal circulation denitrification treatment system according to claim 8, characterized in that, The lower end of the three-way connector (702) is fixedly provided with a sealing sleeve (76), and the valve stem (71) can slide through the inner hole of the sealing sleeve (76), and the valve stem (71) and the sealing sleeve (76) slide and seal.

10. The industrial wastewater internal circulation denitrification treatment system according to claim 1, characterized in that, A valve (52) is installed on the pumping pipe (51). The valve (52) is located on the side of the pumping pipe (51) close to the anaerobic tank (1) and downstream of the connecting pipe (7).

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