A double sludge reflux sewage treatment device for enhancing denitrification and dephosphorization

Abstract

The application discloses a double-sludge reflux sewage treatment device for strengthening denitrification and phosphorus removal, and belongs to the sewage treatment equipment. The double-sludge reflux sewage treatment device for strengthening denitrification and phosphorus removal comprises a water inlet pipe, an original water pool, a sewage lifting pump, a water flow pipeline assembly system, a sewage treatment combined unit, two-stage solid-liquid separation zones, a sludge reflux, a discharge unit, a water outlet pipe and a device room PLC controller module assembly, and the sewage treatment combined unit is provided with a first-stage aerobic tank; the first-stage aerobic tank is provided with an oscillation device and a cloth-hanging biological carrier piece; the oscillation device is connected with the cloth-hanging biological carrier piece; and the cloth-hanging biological carrier piece is provided with biological fillers. The biological fillers are vibrated by the oscillation device to make the sludge on the surface of the biological fillers, which is aged and loses activity, fall off, so that the biological membrane on the biological fillers is renewed, sludge double reflux is realized, nitrification and phosphorus absorption reactions are more thorough, and the like.

Description

Technical Field

[0001] This invention relates to wastewater treatment equipment, and more particularly to a dual sludge return wastewater treatment equipment for enhanced nitrogen and phosphorus removal. Background Technology

[0002] With the acceleration of industrialization and urbanization, water pollution has become increasingly serious, with nitrogen and phosphorus pollution being particularly prominent. This not only concerns the sustainable use of water resources but also directly impacts our ecological environment. Consequently, some wastewater treatment equipment has emerged on the market, such as those with announcement numbers CN218058731U and CN214653942U. This type of wastewater treatment equipment is based on A... 2 Produced using process O, A 2 The O process combines A / O (Anoxic-Oxic) biological denitrification and A 2 / O (Anaerobic-Oxic) biological phosphorus removal features simultaneous nitrogen and phosphorus removal. However, when using this type of wastewater treatment equipment, there are problems. Aged sludge in the wastewater or sticky impurities in the influent can easily cover the biological packing material in the aerobic tank. As the amount of covered sludge increases, the contact between the aerobic bacteria and the wastewater is limited, which greatly reduces the wastewater treatment efficiency. It is necessary to regularly remove the aged sludge and adhering impurities on the biological packing material, which is difficult to handle.

[0003] And, A 2 In wastewater treatment processes, nitrogen and phosphorus removal involves multiple biochemical reactions such as nitrification, denitrification, phosphorus uptake and release. Each reaction has different requirements for environmental conditions, substrate type, and microbial composition. Polyphosphate-accumulating bacteria in anaerobic tanks and denitrifying bacteria in anoxic tanks are short-lived microorganisms. Short sludge age is beneficial for phosphorus removal and denitrification. However, autotrophic nitrifying bacteria in aerobic tanks have a slow growth rate and a long generation cycle. To make autotrophic nitrifying bacteria the dominant species, the aerobic stage needs a long sludge age of 20-30 days. However, a long sludge age results in insufficient discharge of phosphorus-containing sludge, and a higher sludge age may cause phosphorus to be released from the phosphorus-containing sludge again, which is not conducive to phosphorus removal in the system. During the denitrification and phosphorus removal process, denitrifying bacteria and polyphosphate-accumulating bacteria coexist and compete for carbon sources. Denitrifying bacteria will preferentially take up carbon sources. Insufficient carbon sources in the anaerobic stage will inhibit the release of phosphorus by polyphosphate-accumulating bacteria, thus leading to a poorer final phosphorus removal effect. In order to ensure a good phosphorus removal effect, the anaerobic stage needs to have sufficient carbon sources for polyphosphate-accumulating bacteria to absorb. Generally, the anaerobic tank (SP / SBOD) is controlled below 0.06, and the sludge load is controlled above 0.10 kg BOD5 / (kg MLSS·d).

[0004] A 2The main problems in the nitrogen and phosphorus removal process of the O process lie in the contradiction between the long sludge age of nitrification and the short sludge age of phosphorus release and denitrification, the contradiction in carbon source allocation between denitrification and phosphorus release, and the disruption of the anaerobic environment by sludge recirculation, which affects phosphorus removal. Since the three types of bacteria (nitrifying bacteria, denitrifying bacteria, and polyphosphate-accumulating bacteria) that perform different functions cannot grow under their respective optimal conditions, the carbon source contradiction and the NOx-N recirculation problem cannot be fundamentally solved. Nitrogen and phosphorus removal are mutually restrictive, and the nitrogen and phosphorus removal rates cannot simultaneously reach their highest levels. To solve these problems, this invention proposes a dual sludge recirculation wastewater treatment device and matching system for enhanced nitrogen and phosphorus removal, aiming to address the issue of aged sludge easily covering the biological packing material in traditional wastewater treatment equipment. Dual sludge recirculation makes nitrification and phosphorus uptake reactions more thorough. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal that can overcome or at least partially solve the above problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal includes an inlet pipe, a raw water tank, a wastewater lift pump, a water flow pipeline system, a wastewater treatment unit, a two-stage solid-liquid separation zone, a sludge return and discharge unit, a series of supporting testing instruments, an outlet pipe, and a PLC controller module in the equipment room. Wastewater flows into the raw water tank through the inlet pipe. The wastewater lift pump is located in the raw water tank. The wastewater lift pump and the water flow pipeline system lift the wastewater in the raw water tank and then flow it in stages into the wastewater treatment unit and the solid-liquid separation zone. The wastewater is treated, clarified, disinfected, and discharged through the outlet pipe. The wastewater treatment unit and the sludge return and discharge unit are connected through the water flow pipeline system.

[0008] The water flow pipeline assembly system includes water flow pipelines and flow meters and flow distribution regulating valves installed on water flow pipelines in different locations. The flow meters and flow distribution regulating valves are connected to the PLC controller module of the equipment room through electrical control lines. The sewage treatment combined unit has a first-stage aerobic tank, which is equipped with a cloth-type biological carrier and aeration facilities.

[0009] The first-stage aerobic tank is equipped with a shaking device, which is connected to the cloth-mounted biological carrier and can drive the cloth-mounted biological carrier to shake horizontally and laterally.

[0010] Furthermore, the wastewater treatment unit also includes a pre-denitrification tank, an anaerobic tank, a first-stage solid-liquid separation zone, an anoxic tank, a second-stage aerobic tank, and a second-stage solid-liquid separation zone, wherein the pre-denitrification tank, anaerobic tank, first-stage aerobic tank, first-stage solid-liquid separation zone, anoxic tank, second-stage aerobic tank, second-stage solid-liquid separation zone, and equipment room are arranged sequentially from front to back on the entire wastewater treatment device;

[0011] The sludge return and discharge unit is installed between the pre-denitrification tank, the first-stage solid-liquid separation zone, the anoxic tank, and the second-stage solid-liquid separation zone via sludge return pipe fittings.

[0012] The supporting series of testing instruments includes a dissolved oxygen detector, an oxidation-reduction potential detector, and a sludge concentration detector. Dissolved oxygen detectors are installed in both the first and second aerobic tanks of the anaerobic tank, oxidation-reduction potential detectors are installed in both the anaerobic and anoxic tanks of the pre-denitrification tank, and sludge concentration detectors are installed in both the pre-denitrification tank and the anoxic tank. The supporting series of testing instruments are connected to the PLC controller module of the equipment room through electrical control circuits. The PLC controller module of the equipment room and the supporting series of testing instruments are all connected to an external power supply through corresponding circuits.

[0013] Furthermore, the sludge return and discharge unit includes a first-stage solid-liquid separation zone sludge return pipe group, a first-stage solid-liquid separation zone sludge discharge pipe group, a first-stage solid-liquid separation zone sludge return internal carbon source pipe group, a second-stage solid-liquid separation zone sludge return pipe group, and a second-stage solid-liquid separation zone sludge discharge pipe group.

[0014] The sludge return pipe assembly of the first-stage solid-liquid separation zone is equipped with a pump and an electric valve. One end of the sludge return pipe assembly is connected to the first-stage solid-liquid separation zone through the pump and the electric valve, and the other end is connected to the pre-denitrification tank. The sludge return pipe assembly of the first-stage solid-liquid separation zone can return the sludge of the first-stage solid-liquid separation zone to the pre-denitrification tank.

[0015] The carbon source pipe assembly in the first-stage solid-liquid separation zone is equipped with a pump and an electric valve. One end of the carbon source pipe assembly in the first-stage solid-liquid separation zone is connected to the first-stage solid-liquid separation zone through the pump and the electric valve, and the other end is connected to the anoxic tank. The carbon source pipe assembly in the first-stage solid-liquid separation zone can return the carbon source in the sludge in the first-stage solid-liquid separation zone to the anoxic tank.

[0016] The sludge discharge pipe assembly of the first-stage solid-liquid separation zone is installed at the bottom of the first-stage solid-liquid separation zone. The first-stage solid-liquid separation zone sludge discharge pipe assembly is equipped with a pump and an electric valve, which can discharge the sludge in the first-stage solid-liquid separation zone to the outside.

[0017] The sludge return pipe assembly in the second-stage solid-liquid separation zone is equipped with a pump and an electric valve. One end of the sludge return pipe assembly is connected to the second-stage solid-liquid separation zone, and the other end is connected to the anoxic tank. The sludge return pipe assembly in the second-stage solid-liquid separation zone can return the sludge in the second-stage solid-liquid separation zone to the anoxic tank.

[0018] The sludge discharge pipe assembly for the second-stage solid-liquid separation zone is installed at the bottom of the second-stage solid-liquid separation zone. The sludge discharge pipe assembly for the second-stage solid-liquid separation zone is equipped with a pump and an electric valve, which can discharge the sludge in the second-stage solid-liquid separation zone to the outside.

[0019] Preferably, the oscillation device includes a cylinder assembly, a sliding support frame, a smooth inner rod, a support plate, and a rubber buffer pad. The support plate is installed on the left and right edges of the first-stage aerobic tank. Both ends of the smooth inner rod are installed on the support plate. The sliding support frame is installed on the smooth inner rod. One end of the sliding support frame is connected to the cylinder assembly, and the other end of the sliding support frame is equipped with a rubber buffer pad. The cylinder assembly can push the sliding support frame to slide laterally left and right on the smooth inner rod.

[0020] Furthermore, the sliding support frame has a crossbeam, and the cloth-hanging biological carrier can be a linear hanging biological carrier or a soft cloth-hanging biological carrier, which is vertically hung on the crossbeam of the sliding support frame.

[0021] Furthermore, the sliding support frame can also be equipped with an L-shaped stirring rod. One end of the L-shaped stirring rod is laterally connected to the sliding support frame, and the other end of the L-shaped stirring rod is equipped with a brush head. The installation area of ​​the brush head is located above the aeration head assembly in the bottom aeration facility of the first-stage aerobic tank.

[0022] Preferably, the aeration head assembly includes a microporous aeration head and a sludge collection component. The aeration head assembly is connected to the blower aeration equipment through an aeration pipe. The aeration pipe is equipped with a frequency conversion flow distribution regulating valve, which is connected to the PLC controller module of the equipment through an electrical control circuit. The end of the aeration pipe is connected to a microporous aeration head, and the sludge collection component is installed around the lower part of the microporous aeration head. The sludge collection component can collect or gather sludge and other debris that settles on the microporous aeration head.

[0023] Furthermore, the upper surface of the microporous aeration head is provided with a soft arc-shaped film element with aeration holes. When the aeration volume delivered to the microporous aeration head by the aeration pipe is adjusted by the frequency conversion flow distribution regulating valve, the soft arc-shaped film element on the microporous aeration head can be shaken, thereby shaking off the sludge and debris that have settled on the soft arc-shaped film element in the microporous aeration head. These sludge and debris can fall into the sludge collection element.

[0024] Furthermore, both the first-stage aerobic tank and the second-stage aerobic tank are equipped with slag-blocking sleeve assemblies at their outlets. The slag-blocking sleeve assembly consists of an outer sleeve, an inner sleeve, and an adapter. The outer sleeve is fixedly installed on the outside of the inner sleeve by a fixed bracket. The adapter is installed on the inner sleeve, and the inner sleeve is equipped with an outlet pipe. This design can effectively prevent scum, foam, and other debris on the surface of the aerobic tank from flowing into the solid-liquid separation zone.

[0025] Preferably, the bottom of the outer sleeve is funnel-shaped, and the bottom end of the funnel-shaped inner sleeve is connected to a water outlet pipe.

[0026] Furthermore, submersible mixing components are installed in the pre-denitrification tank, anaerobic tank, and anoxic tank. The submersible mixing components include a support, a guide rod, and a submersible mixer. The support is installed on the pre-denitrification tank, anaerobic tank, and anoxic tank. One side of the guide rod is installed on the support, and the submersible mixer is installed on the other side of the guide rod. The support is provided with a U-shaped groove. By rotating the guide rod in the U-shaped groove, the orientation of the submersible mixer can be changed. This design can prevent the substances in the pre-denitrification tank, anaerobic tank, and anoxic tank from eccentrically accumulating, which would make the center of gravity of the entire dual sludge return wastewater treatment device unstable and cause it to tilt or deviate.

[0027] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0028] 1. By installing a pre-denitrification tank before the anaerobic tank in the AO process of wastewater treatment, the organic matter in some of the influent can reduce NO in the returned sludge. X -N denitrification can reduce NO X -N competes with the carbon source for phosphorus release by polyphosphate-accumulating bacteria in the anaerobic zone, resulting in better anaerobic conditions in the anaerobic tank and enhanced phosphorus removal.

[0029] Biological phosphorus removal and biological nitrogen removal adopt an independent sludge return and discharge system to resolve the contradiction of sludge age in the original sewage treatment equipment for nitrogen and phosphorus removal;

[0030] Arranging biological packing material in the first-stage aerobic tank is beneficial for enriching nitrifying bacteria with short generation cycles and enhancing the nitrification reaction effect.

[0031] The segmented influent design allows for adjustable influent ratios. Part of the influent enters the pre-denitrification tank to remove nitrate nitrogen carried by the returned sludge, which can disrupt the anaerobic phosphorus release environment. Another part enters the anaerobic zone, where organic matter is converted into intermediates such as volatile fatty acids (VFA) by microorganisms under anaerobic conditions, and synthesized into internal carbon sources such as polyhydroxyalkanoates (PHA), which are stored within the microorganisms. The influent then enters the first-stage aerobic zone. Due to abundant dissolved oxygen and ammonia nitrogen matrix, nitrification primarily occurs in this zone, converting ammonia nitrogen into nitrate nitrogen. A small portion of organic matter is oxidized here, while most remains in the system. This organic matter is then returned to the anoxic tank along with some of the carbon sources from the returned sludge in the first-stage solid-liquid separation zone. In the anoxic tank, denitrification (using the internal carbon sources (PHA, etc.) stored in the anaerobic zone) reduces nitrate nitrogen to nitrogen gas, achieving denitrification. Because the anoxic zone utilizes the internal carbon sources stored in the anaerobic zone for denitrification, it achieves efficient utilization of organic matter and reduces the need for external carbon sources.

[0032] Furthermore, the first-stage aerobic tank converts most of the ammonia nitrogen in the influent into nitrate nitrogen. The anoxic tank follows, with the nitrate nitrogen carried by the effluent from the first-stage aerobic tank flowing into the anoxic tank by gravity, eliminating the need for nitrification liquor recirculation and saving energy. The purpose of setting up a second-stage aerobic tank after the anoxic tank is to further remove ammonia nitrogen from the water. Subsequently, the mixed liquor enters the second-stage solid-liquid separation zone. The sludge return pipe group in the second-stage solid-liquid separation zone returns the nitrate nitrogen produced in the second-stage aerobic section and the sludge from the second-stage solid-liquid separation zone to the anoxic section, maintaining the biomass in the system. It can also bring the internal carbon source in the microorganisms back to the anoxic section, further reducing the need for external carbon sources.

[0033] 2. By installing a shaking device in the first-stage aerobic tank, the sludge on the biological carrier can be shaken off by the shaking device. This can prevent aging sludge from adhering to the surface of the biofilm, which would affect the contact between aerobic bacteria and wastewater and reduce the reaction efficiency. At the same time, the shaking of the biological carrier is conducive to the contact between aerobic bacteria and wastewater, which can increase the nitrification reaction effect.

[0034] The design of the inner and outer sleeve type slag-blocking sleeve assembly can intercept scum, foam and other debris on the surface of the aerobic tank within the aerobic tank. Wastewater flows from the bottom of the outer sleeve into the inner sleeve and then into the next process. This design can prevent impurities in the wastewater from flowing into the outlet pipe of the subsequent pipeline and causing blockage, and can also prevent impurities in the wastewater from flowing into the next process and affecting the treatment effect.

[0035] 3. By installing sludge collection components around the lower part of the microporous aeration head, the sludge collection components can collect or gather the sludge and other debris that settles on the microporous aeration head, which can prevent sludge from accumulating on the microporous aeration head and prevent the air outlet of the microporous aeration head from being blocked by sludge.

[0036] By adjusting the aeration volume delivered from the aeration pipe to the microporous aeration head through the variable frequency flow distribution regulating valve, the soft arc-shaped film on the microporous aeration head can be shaken, thereby shaking off the sludge and debris that have settled on the soft arc-shaped film in the microporous aeration head. These sludge and debris can fall into the sludge collection device, which can effectively prevent sludge from settling on the aeration head.

[0037] The L-shaped stirring rod and brush head installed on the support rod can agitate the sewage on the microporous aeration head, which can better clean the sludge on the microporous aeration head and ensure its excellent aeration effect.

[0038] In summary, this invention, through its oscillation device design, avoids the adhesion of aged sludge to the surface of the biological packing material; the use of a sludge-blocking sleeve design prevents blockage of the effluent pipe; and the sludge collection device outside the microporous aeration head collects sludge and other debris that settles on the aeration head. Furthermore, by optimizing the wastewater treatment process and corresponding parameters throughout the entire wastewater treatment device, such as influent carbon source distribution, hydraulic retention time (HRT), sludge age (SRT), and dissolved oxygen (DO) concentration, this invention significantly improves the removal efficiency of nitrogen and phosphorus from wastewater. Additionally, the device or system utilizes an internal carbon source for denitrification, reducing the need for external carbon sources, resulting in relatively low sludge production and lower operating costs. Attached Figure Description

[0039] Figure 1 This is a three-dimensional schematic diagram of a dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal proposed in this invention.

[0040] Figure 2 This is a schematic diagram of the process flow of a dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal proposed in this invention.

[0041] Figure 3 This is a front view of a horizontal longitudinal section of a dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal proposed in this invention, viewed from the left front to the right.

[0042] Figure 4 This is a three-dimensional schematic diagram of the location of the oscillation device in a dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal proposed in this invention.

[0043] Figure 5 This is a three-dimensional schematic diagram of the microporous aeration head area in a dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal proposed in this invention.

[0044] Figure 6 This is a partial three-dimensional schematic diagram of the sliding support rod with an L-shaped stirring rod and a brush head component added laterally in a dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal proposed in this invention.

[0045] Figure 7 This is a three-dimensional schematic diagram of the sludge-returning sleeve area in a dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal proposed in this invention.

[0046] Figure 8 This is a top view of the sludge-returning sleeve area in a dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal proposed in this invention.

[0047] In the diagram: 1. Raw water tank; 2. Sewage lift pump; 3. Water flow pipeline assembly system; 4. Sludge return and discharge unit; 5. Flow meter; 6. Flow distribution regulating valve; 7. First-stage aerobic tank; 8. Hanging cloth biological carrier; 9. Shaking device; 10. Pre-denitrification tank; 11. Anaerobic tank; 12. Anoxic tank; 13. Second-stage aerobic tank; 14. Cylinder assembly; 15. Sliding support frame; 16. Smooth inner rod; 17. Rebar buffer pad; 18. Crossbeam; 19. L-shaped stirring rod; 20. Brush head; 21. Microporous aeration head; 22. Sludge collection device; 23. Outer sleeve; 24. Inner sleeve; 25. Outlet pipe; 26. Submersible mixer; 27. First-stage solid-liquid separation zone; 28. Second-stage solid-liquid separation zone. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0049] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "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 this 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 this invention.

[0050] Example 1:

[0051] Reference Figures 1-3A dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal includes a raw water tank 1, a wastewater lift pump 2, a water flow pipeline assembly system 3, a flow meter 5, a flow distribution regulating valve 6, a pre-denitrification tank 10, an anaerobic tank 11, a first-stage aerobic tank 7, a first-stage solid-liquid separation zone, an anoxic tank 12, and a second-stage aerobic tank 13. The device includes sludge return from the first-stage solid-liquid separation zone, sludge discharge from the first-stage solid-liquid separation zone, carbon source in the returned sludge from the first-stage solid-liquid separation zone, sludge return from the second-stage solid-liquid separation zone, sludge discharge from the second-stage solid-liquid separation zone, aeration in the first-stage aerobic tank 7, aeration in the second-stage aerobic tank 13, a dissolved oxygen (DO) detector in the anaerobic tank 11, a dissolved oxygen (DO) detector in the first-stage aerobic tank 7, a dissolved oxygen (DO) detector in the second-stage aerobic tank 13, and an oxidation-reduction electrode in the pre-denitrification tank 10. The system consists of an ORP (Oxidation-Reduction Potential) detector, an ORP detector for anaerobic tank 11, an ORP detector for anoxic tank 12, a sludge concentration (MLSS) detector for pre-denitrification tank 10, and a sludge concentration (MLSS) detector for anoxic tank 12. Wastewater from raw water tank 1 is pumped by wastewater lift pump 2 and then enters pre-denitrification tank 10 and anaerobic tank 11 in stages for treatment. Simultaneously, sludge returned from the first-stage solid-liquid separation zone also enters pre-denitrification tank 10. The effluent from the first-stage aerobic tank 7, after passing through the first-stage solid-liquid separation zone, flows by gravity into anoxic tank 12 and second-stage aerobic tank 13 for treatment. Simultaneously, carbon sources from the sludge returned from the second-stage solid-liquid separation zone and the sludge returned from the first-stage solid-liquid separation zone also enter anoxic tank 12. The effluent from the second-stage aerobic tank 13, after clarification in the second-stage solid-liquid separation zone, is disinfected and discharged.

[0052] The sewage lift pump 2 is a submersible sewage pump with variable frequency and adjustable flow rate. The sewage lift pump 2 is connected to the inlet pipe, and a flow meter 5 is installed on the inlet pipe. The frequency of the sewage lift pump 2 is automatically adjusted to maintain a relatively constant value by associating the inlet flow rate value set by the system with the flow meter 5 and the programmable controller (PLC) module. The inlet pipe enters the system in two sections, one section enters the pre-denitrification tank 10 and the other section enters the anaerobic tank 11. The inlet ratio can be adjusted by the flow distribution regulating valve 6.

[0053] The pre-denitrification tank 10 has a top-feed water intake method. A submersible mixer 26 is installed inside the pre-denitrification tank 10. The submersible mixer 26 can be one of the paddle type, propeller type, or turbine type. An oxidation-reduction potential (ORP) detector and a sludge concentration (MLSS) detector are installed inside the pre-denitrification tank 10. The oxidation-reduction potential (ORP) of the pre-denitrification tank 10 does not exceed 50mV. The mixed liquor suspended solids (MLSS) concentration of the pre-denitrification tank 10 is 2-4g / L. The hydraulic retention time of the pre-denitrification tank 10 is 1-2h. The pre-denitrification tank 10 is connected to the anaerobic tank 11 through a baffle with openings at the bottom. The effluent flows into the anaerobic tank 11 by gravity.

[0054] The anaerobic tank 11 is fed into the bottom. A submersible mixer 26 is installed inside the anaerobic tank 11. The submersible mixer 26 can be one of the following: paddle type, propeller type, or turbine type. An oxidation-reduction potential (ORP) detector and a dissolved oxygen (DO) detector are installed inside the anaerobic tank 11. The hydraulic retention time of the anaerobic tank 11 is 1-2 hours. The ORP of the anaerobic tank 11 is not higher than -100mV. The dissolved oxygen of the anaerobic tank 11 is not higher than 0.2mg / L. The anaerobic tank 11 is connected to the guide tube of the first-stage aerobic tank 7 through a baffle with openings at the top. The effluent flows into the first-stage aerobic tank 7 by gravity from the bottom.

[0055] The first-stage aerobic tank 7 has a top-inlet water intake method. The first-stage aerobic tank 7 is equipped with aeration head components and biological packing materials. The aeration head components can be one or more of the following: disc type, pipe type, and flexible hose type. The biological packing materials can be one or more of the following: combined fiber packing materials, soft fiber packing materials, porous suspended ball packing materials, inclined suspended porous suspended packing materials, and PPC polyurethane sponge packing materials. The first-stage aerobic tank 7 is equipped with a dissolved oxygen (DO) detector. The hydraulic retention time of the first-stage aerobic tank 7 is 5-8 hours. The dissolved oxygen in the first-stage aerobic tank 7 is not less than 2 mg / L. The first-stage aerobic tank 7 has a top-outlet water outlet. The outlet water is connected to the first-stage solid-liquid separation zone through a water collection pipe with a slag-blocking sleeve and a baffle plate. The outlet water flows into the first-stage solid-liquid separation zone by gravity.

[0056] The first-stage solid-liquid separation zone can be either vertical flow or radial flow. The radial flow solid-liquid separation zone is equipped with sludge scraping and slag scraping devices. The bottom sludge collection area of ​​the first-stage solid-liquid separation zone is equipped with a sludge pump, a sludge return electric valve, a sludge discharge electric valve, and a sludge return carbon source electric valve. After the sludge and water are separated in the first-stage solid-liquid separation zone, the clear water is collected by the water collection weir and then flows by gravity through the baffle from the top into the anoxic tank 12.

[0057] The anoxic tank 12 is fed from the top. A submersible mixer 26 is installed inside the anoxic tank 12. The submersible mixer 26 can be one of the following: paddle type, propeller type, or turbine type. An oxidation-reduction potential (ORP) meter and a sludge concentration (MLSS) meter are installed inside the anoxic tank 12. The hydraulic retention time of the anoxic tank 12 is 6-9 hours. The ORP of the anoxic tank 12 is not higher than 50mV. The MLSS concentration of the mixed liquor in the anoxic tank 12 is 3.5-5g / L. The anoxic tank 12 is connected to the second-stage aerobic tank 13 through a bottom opening and a baffle. The effluent flows into the second-stage aerobic tank 13 by gravity.

[0058] The second-stage aerobic tank 13 is fed into the bottom. It is equipped with aeration head components, which can be one or more of disc, pipe, and flexible hose types. A dissolved oxygen (DO) detector is installed in the second-stage aerobic tank 13. The hydraulic retention time of the second-stage aerobic tank 13 is 2-4 hours. The dissolved oxygen in the second-stage aerobic tank 13 is not less than 2 mg / L. The water exits from the top of the second-stage aerobic tank 13. The water exits through a collection pipe with a slag-blocking sleeve and is connected to the second-stage solid-liquid separation zone through a baffle. The water then flows into the second-stage solid-liquid separation zone by gravity.

[0059] The second-stage solid-liquid separation zone can be vertical flow type, with good sludge thickening effect. The bottom sludge collection zone is equipped with a sludge pump, a return sludge electric valve, and a sludge discharge electric valve. After the sludge and water are separated in the second-stage solid-liquid separation zone, the clear water is collected by the water collection weir and flows into the disinfection unit for disinfection before being discharged.

[0060] Example 2:

[0061] A dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal includes an inlet pipe, a raw water tank 1, a wastewater lift pump 2, a water flow pipeline system 3, a wastewater treatment unit, a sludge return and discharge unit 4, a series of supporting testing instruments, an outlet pipe, and a PLC controller module in the equipment room. Wastewater flows into the raw water tank 1 through the inlet pipe. The wastewater lift pump 2 is located in the raw water tank 1. The wastewater lift pump 2 and the water flow pipeline system 3 lift the wastewater in the raw water tank 1 and then flow it in sections into the wastewater treatment unit and the two-stage solid-liquid separation zone. The wastewater is treated, clarified, disinfected, and discharged through the outlet pipe.

[0062] The water flow pipeline assembly system 3 includes water flow pipelines and flow meters 5 and flow distribution regulating valves 6 installed on water flow pipelines in different locations. Flow meters 5 and flow distribution regulating valves 6 are connected to the PLC controller module of the equipment room through electrical control lines. The sewage treatment combined unit includes a first-stage aerobic tank 7. The first-stage aerobic tank 7 is equipped with a cloth-type biological carrier 8 and aeration facilities.

[0063] The first-stage aerobic tank 7 is equipped with a shaking device 9, which is connected to the hanging biological carrier 8. The shaking device 9 can drive the hanging biological carrier 8 to shake horizontally and laterally. The hanging biological carrier 8 is equipped with biological packing material. The shaking of the hanging biological carrier 8 by the shaking device 9 can prevent aged sludge from adhering to the surface of the biofilm, which would affect the contact between aerobic bacteria and sewage and reduce the reaction efficiency. At the same time, the shaking of the hanging biological carrier 8 is conducive to the contact between aerobic bacteria and sewage, which can increase the nitrification reaction effect.

[0064] This invention is a dual sludge recirculation wastewater treatment device for enhanced nitrogen and phosphorus removal. By using an oscillation device to drive the hanging biological carrier to vibrate, the aging and inactive sludge on the surface of the biological packing is shaken off. This solves the problem that aging sludge and impurities carried by the influent in the original wastewater treatment equipment are difficult to remove from the surface of the biological packing. It is beneficial to the growth and renewal of the biofilm on the biological packing and realizes dual sludge recirculation to make the nitrification and phosphorus absorption reactions more thorough.

[0065] The wastewater treatment unit also includes a pre-denitrification tank 10, an anaerobic tank 11, a first-stage solid-liquid separation zone 27, an anoxic tank 12, a second-stage aerobic tank 13, and a second-stage solid-liquid separation zone 28. These components are arranged sequentially from front to back within the entire wastewater treatment system.

[0066] The sludge return and discharge unit 4 is installed between the pre-denitrification tank 10, the first-stage solid-liquid separation zone 27, the anoxic tank 12, and the second-stage solid-liquid separation zone 28 via sludge return and discharge pumps and piping.

[0067] The supporting series of testing instruments includes a dissolved oxygen detector, an oxidation-reduction potential detector, and a sludge concentration detector. Dissolved oxygen detectors are installed in anaerobic tank 11, the first-stage aerobic tank 7, and the second-stage aerobic tank 13. Oxidation-reduction potential detectors are installed in pre-denitrification tank 10, anaerobic tank 11, and anoxic tank 12. Sludge concentration detectors are installed in pre-denitrification tank 10 and anoxic tank 12. The supporting series of testing instruments are connected to the PLC controller module in the equipment room through electrical control lines. The PLC controller module in the equipment room and the supporting series of testing instruments are all connected to the external power supply through corresponding lines.

[0068] The sludge return and discharge unit 4 includes a sludge return pipe group for the first-stage solid-liquid separation zone, a sludge discharge pipe group for the first-stage solid-liquid separation zone, a carbon source pipe group for the sludge return from the first-stage solid-liquid separation zone, a sludge return pipe group for the second-stage solid-liquid separation zone, and a sludge discharge pipe group for the second-stage solid-liquid separation zone.

[0069] The sludge return pipe assembly of the first-stage solid-liquid separation zone is equipped with a pump and an electric valve. One end of the sludge return pipe assembly is connected to the first-stage solid-liquid separation zone 27 through the pump and the electric valve, and the other end is connected to the pre-denitrification tank 10. The sludge return pipe assembly of the first-stage solid-liquid separation zone can return the sludge of the first-stage solid-liquid separation zone 27 into the pre-denitrification tank 10.

[0070] The carbon source pipe assembly in the first-stage solid-liquid separation zone is equipped with a pump and an electric valve. One end of the carbon source pipe assembly in the first-stage solid-liquid separation zone is connected to the first-stage solid-liquid separation zone 27 through the pump and the electric valve, and the other end is connected to the anoxic tank 12. The carbon source pipe assembly in the first-stage solid-liquid separation zone can return the carbon source in the sludge in the first-stage solid-liquid separation zone to the anoxic tank 12.

[0071] The sludge discharge pipe assembly of the first-stage solid-liquid separation zone is installed at the bottom of the first-stage solid-liquid separation zone 27. The first-stage solid-liquid separation zone sludge discharge pipe assembly is equipped with a pump and an electric valve, which can discharge the sludge in the first-stage solid-liquid separation zone 27 to the outside.

[0072] The sludge return pipe assembly in the second-stage solid-liquid separation zone is equipped with a pump and an electric valve. One end of the sludge return pipe assembly is connected to the second-stage solid-liquid separation zone 28, and the other end is connected to the anoxic tank 12. The sludge return pipe assembly in the second-stage solid-liquid separation zone can return the sludge in the second-stage solid-liquid separation zone 28 to the anoxic tank 12.

[0073] The sludge discharge pipe assembly of the second-stage solid-liquid separation zone is installed at the bottom of the second-stage solid-liquid separation zone 28. The sludge discharge pipe assembly of the second-stage solid-liquid separation zone is equipped with a pump and an electric valve, which can discharge the sludge in the second-stage solid-liquid separation zone 28 to the outside.

[0074] Among them, the pumps on the carbon source pipe group and sludge discharge pipe group in the first-stage solid-liquid separation zone and the sludge return pipe group in the second-stage solid-liquid separation zone are shared with the sludge return.

[0075] The oscillation device 9 includes a cylinder assembly 14, a sliding support frame 15, a smooth inner rod 16, a support plate, and a rubber buffer pad 17. The support plate is installed on the left and right edges of the first-stage aerobic tank 7. The two ends of the smooth inner rod 16 are installed on the support plate. The sliding support frame 15 is installed on the smooth inner rod 16. One end of the sliding support frame 15 is connected to the cylinder assembly 14, and the other end of the sliding support frame 15 is equipped with the rubber buffer pad 17. The cylinder assembly 14 can push the sliding support frame 15 to slide horizontally and left and right on the smooth inner rod 16.

[0076] The sliding support frame 15 has a crossbeam 18. The cloth-hanging biological carrier 8 can be a linear hanging biological carrier or a soft cloth-hanging biological carrier. The cloth-hanging biological carrier 8 is vertically hung on the crossbeam 18 of the sliding support frame 15. Biological fillers can be loaded on the cloth-hanging biological carrier 8.

[0077] An L-shaped stirring rod 19 can also be provided on the sliding support frame 15. One end of the L-shaped stirring rod 19 is connected to the side of the sliding support frame 15, and the other end of the L-shaped stirring rod 19 is provided with a brush head 20. The installation area of ​​the brush head 20 is located above the aeration head assembly in the bottom aeration facility of the first-stage aerobic tank 7. The L-shaped stirring rod 19 and the brush head 20 provided on the support rod can agitate the sewage on the microporous aeration head 21, which can better clean the sludge on the microporous aeration head 21 and ensure its excellent aeration effect.

[0078] The aeration head assembly includes a microporous aeration head 21 and a sludge collection component 22. The aeration head assembly is connected to the blower aeration equipment through an aeration pipe. The aeration pipe is equipped with a frequency conversion flow distribution regulating valve, which is connected to the PLC controller module of the equipment through an electrical control circuit. The end of the aeration pipe is connected to the microporous aeration head 21. The sludge collection component 22 is installed around the lower part of the microporous aeration head 21. The sludge collection component 22 can collect or gather the sludge and debris that settles on the microporous aeration head 21.

[0079] The top surface of the microporous aeration head 21 is provided with a soft arc-shaped film element with aeration holes. When the aeration volume delivered to the microporous aeration head 21 by the aeration pipe is adjusted by the frequency conversion flow distribution regulating valve, the soft arc-shaped film element on the microporous aeration head 21 can be shaken, thereby shaking off the sludge and debris that have settled on the soft arc-shaped film element in the microporous aeration head 21. These sludge and debris can fall into the sludge collection part 22.

[0080] Example 3:

[0081] Reference Figures 4-6 Based on Example 2, the difference is that both the first-stage aerobic tank 7 and the second-stage aerobic tank 13 are equipped with a slag-blocking sleeve assembly at their outlets. The slag-blocking sleeve assembly consists of an outer sleeve 23, an inner sleeve 24, and an adapter. The outer sleeve 23 is fixedly installed on the outside of the inner sleeve 24 by a fixed bracket. The adapter is installed on the inner sleeve 24. The inner sleeve 24 is equipped with an outlet pipe 25 after slag blocking.

[0082] The bottom of the inner sleeve 24 is funnel-shaped, and the bottom end of the funnel-shaped inner sleeve 24 is connected to the water outlet pipe 25. Except for the fixed bracket, the area between the outer sleeve 23 and the inner sleeve 24 is hollowed out.

[0083] By using the design of the slag-blocking sleeve, scum, foam and other debris on the surface of the aerobic tank can be intercepted inside the tank. Wastewater flows from the bottom of the outer sleeve into the inner sleeve and then into the next process through the outlet pipe 25. This design can prevent scum, foam and other debris from flowing into the outlet pipe 25 and causing blockage, and can also prevent scum, foam and other debris from flowing into the next process and affecting the reaction efficiency.

[0084] Example 4:

[0085] Reference Figure 5 Based on Example 2, the difference is that: submersible mixing components are provided in the pre-denitrification tank 10, anaerobic tank 11 and anoxic tank 12. The submersible mixing components include a support, a guide rod and a submersible mixer 26. The support is installed on the pre-denitrification tank 10, anaerobic tank 11 and anoxic tank 12. One side of the guide rod is installed on the support and the submersible mixer 26 is installed on the other side of the guide rod. The support is provided with a U-shaped groove. By rotating the guide rod in the U-shaped groove, the orientation of the submersible mixer 26 can be changed.

[0086] This design prevents substances from unilaterally accumulating in the pre-denitrification tank 10, anaerobic tank 11, and anoxic tank 12, thus preventing the entire dual sludge return wastewater treatment device from becoming unstable and tilting or deviating.

[0087] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A dual sludge return sewage treatment device for enhanced nitrogen and phosphorus removal, comprising an inlet pipe, a raw water tank (1), a sewage lift pump (2), a water flow pipeline assembly system (3), a sewage treatment combined unit, a first-stage solid-liquid separation zone (27), a second-stage solid-liquid separation zone (28), a sludge return and discharge unit (4), a series of supporting testing instruments, an outlet pipe, and a PLC controller module assembly in the equipment room. Sewage flows into the raw water tank (1) through the inlet pipe. The sewage lift pump (2) is located in the raw water tank (1). The sewage lift pump (2) and the water flow pipeline assembly system (3) lift the sewage in the raw water tank (1) and then enter the sewage treatment combined unit in sections. The treated sewage is finally clarified in the second-stage solid-liquid separation zone (28), disinfected to meet the standards, and then discharged through the outlet pipe. The water flow pipeline assembly system (3) includes water flow pipelines and flow meters (5) and flow distribution regulating valves (6) installed on water flow pipelines in different locations. The flow meters (5) and flow distribution regulating valves (6) are connected to the PLC controller module assembly in the equipment room through electrical control lines. The sewage treatment combined unit includes a first-stage aerobic tank (7). The first-stage aerobic tank (7) is equipped with a hanging biological carrier (8) and aeration facilities. Its features are, The first-stage aerobic tank (7) is equipped with an oscillation device (9), which is connected to the hanging biological carrier (8) and can drive the hanging biological carrier (8) to vibrate horizontally.

2. The enhanced nitrogen and phosphorus removal dual sludge return wastewater treatment device according to claim 1, characterized in that, The wastewater treatment unit also includes a pre-denitrification tank (10), an anaerobic tank (11), a first-stage aerobic tank (7), a first-stage solid-liquid separation zone (27), an anoxic tank (12), a second-stage aerobic tank (13), and a second-stage solid-liquid separation zone (28). The pre-denitrification tank (10), anaerobic tank (11), first-stage aerobic tank (7), first-stage solid-liquid separation zone (27), anoxic tank (12), second-stage aerobic tank (13), and second-stage solid-liquid separation zone (28) are arranged sequentially from front to back on the entire wastewater treatment device. The sludge return and discharge unit (4) is installed between the pre-denitrification tank (10), the first-stage solid-liquid separation zone (27), the anoxic tank (12), and the second-stage solid-liquid separation zone (28) via a sludge return and discharge pump and piping. The supporting series of testing instruments includes a dissolved oxygen detector, an oxidation-reduction potential detector, and a sludge concentration detector. Dissolved oxygen detectors are installed in the anaerobic tank (11), the first-stage aerobic tank (7), and the second-stage aerobic tank (13). Oxidation-reduction potential detectors are installed in the pre-denitrification tank (10), the anaerobic tank (11), and the anoxic tank (12). Sludge concentration detectors are installed in the pre-denitrification tank (10) and the anoxic tank (12). The supporting series of testing instruments are connected to the PLC controller module of the equipment room through electrical control lines. The PLC controller module of the equipment room and the supporting series of testing instruments are connected to the external power supply through corresponding lines.

3. The enhanced nitrogen and phosphorus removal dual sludge return wastewater treatment device according to claim 2, characterized in that, The sludge return and discharge unit (4) includes a first-stage solid-liquid separation zone sludge return pipe group, a first-stage solid-liquid separation zone sludge discharge pipe group, a first-stage solid-liquid separation zone sludge return carbon source pipe group, a second-stage solid-liquid separation zone sludge return pipe group, and a second-stage solid-liquid separation zone sludge discharge pipe group. The sludge return pipe assembly of the first-stage solid-liquid separation zone is equipped with a pump and an electric valve. One end of the sludge return pipe assembly is connected to the first-stage solid-liquid separation zone (27) through the pump and the electric valve, and the other end is connected to the pre-denitrification tank (10). The sludge return pipe assembly of the first-stage solid-liquid separation zone can return the sludge of the first-stage solid-liquid separation zone (27) to the pre-denitrification tank (10). The carbon source tube assembly in the return sludge of the first-stage solid-liquid separation zone is equipped with a pump and an electric valve. One end of the carbon source tube assembly in the return sludge of the first-stage solid-liquid separation zone is connected to the first-stage solid-liquid separation zone (27) through the pump and the electric valve, and the other end is connected to the anoxic tank (12). The carbon source tube assembly in the return sludge of the first-stage solid-liquid separation zone can return the carbon source in the sludge of the return sludge of the first-stage solid-liquid separation zone to the anoxic tank (12). The first-stage solid-liquid separation zone sludge discharge pipe assembly is installed at the bottom of the first-stage solid-liquid separation zone (27). The first-stage solid-liquid separation zone sludge discharge pipe assembly is equipped with a pump and an electric valve, which can discharge the sludge in the first-stage solid-liquid separation zone (27) to the outside. The sludge return pipe assembly of the second-stage solid-liquid separation zone is equipped with a pump and an electric valve. One end of the sludge return pipe assembly is connected to the second-stage solid-liquid separation zone (28), and the other end is connected to the anoxic tank (12). The sludge return pipe assembly of the second-stage solid-liquid separation zone can return the sludge in the second-stage solid-liquid separation zone (28) to the anoxic tank (12). The sludge discharge pipe assembly of the second-stage solid-liquid separation zone is installed at the bottom of the second-stage solid-liquid separation zone (28). The sludge discharge pipe assembly of the second-stage solid-liquid separation zone is equipped with a pump and an electric valve, which can discharge the sludge in the second-stage solid-liquid separation zone (28) to the outside.

4. The dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal according to claim 1, characterized in that, The oscillation device (9) includes a cylinder assembly (14), a sliding support frame (15), a smooth inner rod (16), a support plate, and a ribbed buffer pad (17). The support plate is installed on the left and right edges of the first-stage aerobic tank (7). The two ends of the smooth inner rod (16) are installed on the support plate. The sliding support frame (15) is installed on the smooth inner rod (16). One end of the sliding support frame (15) is connected to the cylinder assembly (14). The other end of the sliding support frame (15) is equipped with a ribbed buffer pad (17). The cylinder assembly (14) can push the sliding support frame (15) to slide horizontally and left and right on the smooth inner rod (16).

5. The enhanced nitrogen and phosphorus removal dual sludge return wastewater treatment device according to claim 4, characterized in that, The sliding support frame (15) has a crossbeam (18), and the hanging cloth biological carrier (8) can be a linear hanging biological carrier or a soft hanging cloth biological carrier. The hanging cloth biological carrier (8) is vertically hung on the crossbeam (18) of the sliding support frame (15).

6. The enhanced nitrogen and phosphorus removal dual sludge return wastewater treatment device according to claim 5, characterized in that, The sliding support frame (15) can also be provided with an L-shaped stirring rod (19). One end of the L-shaped stirring rod (19) is connected to the side of the sliding support frame (15), and the other end of the L-shaped stirring rod (19) is provided with a brush head (20). The installation area of ​​the brush head (20) is located above the aeration head assembly in the bottom aeration facility of the first-stage aerobic tank (7).

7. The enhanced nitrogen and phosphorus removal dual sludge return wastewater treatment device according to claim 6, characterized in that, The aeration head assembly includes a microporous aeration head (21) and a sludge collection component (22). The aeration head assembly is connected to the blower aeration equipment through an aeration pipe. A variable frequency flow distribution regulating valve is provided on the aeration pipe. The variable frequency flow distribution regulating valve is connected to the PLC controller module assembly between the equipment through an electrical control line. The end of the aeration pipe is connected to the microporous aeration head (21). The sludge collection component (22) is installed around the lower part of the microporous aeration head (21). The sludge collection component (22) can collect or gather the sludge and debris that settles on the microporous aeration head (21).

8. The enhanced nitrogen and phosphorus removal dual sludge return wastewater treatment device according to claim 7, characterized in that, The microporous aeration head (21) has a soft arc-shaped film on its top surface. The soft arc-shaped film has aeration holes. When the aeration volume delivered to the microporous aeration head (21) by the aeration pipe is adjusted by the frequency conversion flow distribution regulating valve, the soft arc-shaped film on the microporous aeration head (21) can be shaken, thereby shaking off the sludge and debris that have settled on the soft arc-shaped film in the microporous aeration head (21). These sludge and debris can fall into the sludge collection device (22).

9. A dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal according to claim 1, characterized in that, Both the first-stage aerobic tank (7) and the second-stage aerobic tank (13) are equipped with a slag-blocking sleeve assembly at their outlets. The slag-blocking sleeve assembly consists of an adapter, an outer sleeve (23), and an inner sleeve (24). The outer sleeve (23) is fixedly installed on the outside of the inner sleeve (24) by a fixed bracket. The adapter is installed on the inner sleeve (24). The water treated by the first-stage aerobic tank (7) and the second-stage aerobic tank (13) flows into the outer sleeve (23) from the bottom and then flows into the inner sleeve (24) from the top. The bottom of the inner sleeve (24) is equipped with an outlet pipe (25) after slag blocking.

10. A dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal according to claim 9, characterized in that, The bottom of the inner sleeve (24) is funnel-shaped, and the bottom end of the funnel-shaped inner sleeve (24) is connected to the water outlet pipe (25).

11. A dual sludge return wastewater treatment device for enhanced nitrogen and phosphorus removal according to claim 2, characterized in that, Submersible mixing components are provided in the pre-denitrification tank (10), anaerobic tank (11) and anoxic tank (12). The submersible mixing components include a support, a guide rod and a submersible mixer (26). The support is installed on the pre-denitrification tank (10), anaerobic tank (11) and anoxic tank (12). One side of the guide rod is installed on the support and the submersible mixer (26) is installed on the other side of the guide rod. The support is provided with a U-shaped groove. By rotating the guide rod in the U-shaped groove, the orientation of the submersible mixer (26) can be changed.

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