A denitrifying bioreactor

Abstract

The application discloses a denitrification biological reactor, which comprises a reactor body, a water inlet distribution system, a primary separator, a secondary separator, a circulating pump and a floating sludge pump. The bottom of the side wall of the reactor body is provided with a first water inlet, a sludge inlet and a circulating connection port; the middle of the side wall is provided with a motor port; the upper part of the side wall is provided with a first water outlet; the top is provided with a breathing port. The water inlet distribution system is installed at the bottom of the reactor body and adopts a perforated water distribution form with a hole diameter of 15-50 mm. The application adopts multiple measures to strengthen the degassing effect, increases the gas-liquid contact area, is beneficial to the escape of free gas from water to the gas phase, converts the gas into dissolved state by using the higher pressure of the lower part of the reactor, and reduces the gas amount of the mixed liquid entering the sedimentation module. The degassing is the prerequisite for sludge sedimentation, the strengthened degassing can improve the sludge sedimentation speed from the source and ensure the sludge-water separation effect.

Description

Technical Field

[0001] This invention relates to the field of denitrification biotechnology, and more particularly to a denitrification bioreactor. Background Technology

[0002] Denitrification is the final step in biological nitrogen removal from wastewater. Its principle is to use denitrifying bacteria to reduce nitrates to nitrogen gas, thus removing them from the wastewater. For common ammonia nitrogen wastewater, denitrification treatment must be combined with nitrification treatment to form a nitrification / denitrification system to achieve biological nitrogen removal. While stand-alone reactors are not widely used, they still have practical significance in the following situations: For wastewater in which nitrogen exists in the form of nitrate, only denitrification treatment is required. Reactors typically employ a larger height-to-diameter ratio to save floor space by increasing water depth, making them a better choice when land is scarce. By integrating mud-water separation, sludge recirculation, and nitrification liquor recirculation into the reactor, the process flow is simplified, making the equipment more optimized and compact.

[0003] In practical applications, the main problem that denitrification bioreactors need to overcome is the issue of sludge runoff and floating caused by air carryover in the sludge, for the following reasons: 1. Reaction mechanism factors: The final product of denitrification is nitrogen gas. Nitrogen gas bubbles are adsorbed on the surface or inside of the sludge, resulting in light sludge that is easy to float and poor sludge-water separation effect. 2. Reactor structural factors: The reactor body is generally bottom inlet and top outlet. As the wastewater flows upward, the water pressure continuously decreases. According to Henry's Law (p=H·x), when the pressure p decreases, the solubility of the gaseous solute in the liquid decreases accordingly, causing the gas to continuously transfer from the dissolved state to the gas phase, forming bubbles that escape and carry the sludge to the surface, which is similar to the principle of an air flotation machine. 3. Separator structural factors: The three-phase separators used in existing reactor bodies are generally hydraulic baffle degassing, that is, by setting baffles to deflect the mixed liquid downwards, the low density of bubbles makes it difficult for them to follow the water flow downwards, thus achieving gas-liquid separation. This type of separator is effective in separating free bubbles, but it is difficult to separate bubbles bound to sludge. Instead, the sludge carrying gas is also blocked by the baffles, accumulating on the reactor liquid surface to form a floating sludge layer. 4. Limitations of Existing Measures: Some existing reactors employ measures to eliminate bubbles and floating sludge, such as hydraulic spraying, hydraulic spraying combined with defoamers, and aeration disturbance defoaming. However, these measures also have obvious drawbacks. For example, hydraulic spraying requires a large amount of water; defoamers are toxic to microorganisms and affect subsequent wastewater reuse membranes; and common substances in wastewater such as proteins, oils, and surfactants can worsen the aeration and defoaming effect. Furthermore, these measures only temporarily disperse the floating sludge and do not remove it. As mentioned earlier, since the cause of floating sludge is inherent to the reactor itself, floating sludge will continue to be generated, leading to a gradual decline in the effectiveness of the aforementioned measures.

[0004] Based on the above, we have designed a denitrification bioreactor to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a denitrification bioreactor.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A denitrification bioreactor includes a reactor body, an influent distribution system, a primary separator, a secondary separator, a circulation pump, and a sludge pump. The reactor body has a first water inlet, a sludge outlet and a circulation connection port at the bottom of the side wall, a motor port in the middle of the side wall, a first water outlet at the top of the side wall, and a vent at the top. The water inlet distribution system is installed at the bottom of the reactor body and adopts a perforated water distribution form with an opening diameter of 15~50mm. After the reactor inlet water flow, the circulating flow from the circulating pump and the recovered floating mud from the floating mud pump are combined, the water is evenly distributed to the bottom of the reactor body. The primary separator is located at the top of the reactor body, either outside or inside the reactor, and is used to collect the mixture after the denitrification reaction and separate nitrogen and sludge from it. The primary separator includes an outer cylinder, an inner cylinder, and a vortex distributor. The upper part of the outer cylinder is cylindrical or prismatic and has a second inlet. The lower part of the outer cylinder is conical or pyramidal and has a second outlet at the bottom. The water flows by gravity to the secondary separator. The side wall of the primary separator is also provided with an inlet trough and a downwardly inclined sludge pipe. The upper part of the outer cylinder is also provided with a vortex water distributor, which is composed of a ring of umbrella-shaped plates. The angle between the plates and the generatrix of the umbrella cone is 10~60°. The plates overlap and have gaps that allow liquid to pass through. The vortex water distributor causes the water flow to be splashed and dispersed into droplets. The inner cylinder is concentric with the outer cylinder, open at both ends, with the bottom end communicating with the outer cylinder and the top end being 17200~800mm lower than the outer cylinder; the upper part of the inner cylinder is provided with a mud-floating pipe at an angle of 30~60° downwards, the mud-floating pipe is connected to the mud-floating pump, and the top of the primary separator has a vent hole. The secondary separator is installed at the bottom of the reactor body.

[0007] Preferably, the reactor body is cylindrical or cuboid in shape, made of metal or reinforced concrete, with a diameter or side length of 3-20m and a height of 8-24m.

[0008] Preferably, when the primary separator is installed outside the reactor body, an overflow trough is installed on the upper part of the reactor body to collect the overflow water from the top of the reactor body. An adjustable weir plate is used. The end of the overflow trough is connected to the overflow port on the side wall of the reactor body. An exhaust gas connection port is also provided on the top of the reactor body.

[0009] Preferably, the surface load u of the primary separator is less than 0.5m. 3 / (m 2 .s).

[0010] Preferably, the secondary separator is a fully enclosed type, including a sedimentation module and a sludge hopper; The sedimentation module has a top plate with a third water inlet on the top plate, which is connected to the second water outlet of the primary separator. Within the sedimentation module, a longitudinal partition divides it into a water distribution zone and a sedimentation zone. The sedimentation zone is equipped with inclined plates (length 0.6~2m, inclination angle 50~60°, spacing 50~150mm, surface loading of the sedimentation zone 0.2~0.75m). 3 / (m 2 .h); The clear liquid above the inclined plate flows out of the sedimentation module and flows out of the reactor body through the water outlet on the side wall of the reactor body; The sedimentation module has a top plate with a second inlet connected to the second outlet of the primary separator. It also has two side plates with an end plate and an end plate at each end. The end plate has a third outlet connected to the first outlet on the upper side wall of the reactor body.

[0011] Preferably, 1 to 3 sludge hoppers are arranged along the length of the sedimentation module below the sedimentation module. The inclination angle of the sludge hoppers is 50 to 60°. Each sludge hopper is equipped with a circulation port, which is controlled by an independent valve and connected to a circulation pump.

[0012] Preferably, one or more secondary separators may be installed at the bottom of the reactor body.

[0013] Preferably, the circulating pump is installed outside the reactor body, with the pump inlet connected to the circulation port of the secondary separator and the pump outlet connected to the inlet water distribution system of the reactor body to mix with the inlet water.

[0014] Preferably, the sludge pump is installed outside the reactor body, with the pump inlet connected to the sludge pipe of the primary separator, and the pump outlet having two destinations: one is a sludge discharge pipe, which discharges the sludge to the sludge treatment system; the other is a sludge recovery pipe, which is connected to the inlet water distribution system of the reactor body and mixes with the inlet water.

[0015] Compared with the prior art, the beneficial effects of the present invention are: (1) The reactor adopts an overflow discharge method. After the floating mud is generated, it will enter the primary separator along with the water flow and will not remain in the reactor to form a floating mud layer. (2) Multiple measures are adopted to enhance the degassing effect: First, in the primary separator, the hydrocyclone distributor disperses the influent into droplets, increasing the gas-liquid contact area, which is conducive to the free gas escaping from the water to the gas phase; Second, the inertial collision of the water flow on the surface of the umbrella-shaped plate promotes the separation of air bubbles carried on the sludge surface; Third, for the air bubbles bound in the sludge that were not removed in the first two steps, the characteristics of the air-bearing sludge being low in density and easy to float are utilized to make it accumulate in the inner cylinder, and then the gas is discharged by the shearing action of the sludge pump, and returned to the reactor or discharge system as needed; Fourth, the higher pressure at the bottom of the reactor is used to convert the gas into a dissolved state, reducing the amount of gas carried by the mixed liquid entering the sedimentation module. Degassing is a prerequisite for sludge settling, and strengthening degassing can improve the sludge settling speed from the source and ensure the sludge-water separation effect; (3) The floating sludge collected in the inner cylinder can be returned to the reactor or discharged from the system as needed, combining the discharge of residual sludge with the removal of floating sludge, achieving two goals at once, thereby avoiding the accumulation of floating sludge and keeping the amount of floating sludge in a balanced and controllable state. (4) The secondary separator adopts inclined plate sedimentation, which has a compact structure and a small footprint.

[0016] (5) The underflow of the secondary separator is returned to the reactor inlet through the circulation pump. The hydraulic stirring provided by the circulation flow ensures the upward flow rate and stirring energy required for the mixing effect of the reactor, replacing mechanical stirring and avoiding the maintenance inconvenience caused by the submersible stirrer.

[0017] (6) The circulating flow rate comes from the bottom of the water distribution zone and does not pass through the inclined plate sedimentation zone. Therefore, the circulating flow rate can be adjusted according to process requirements without affecting the sedimentation effect of the secondary separator. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a denitrification bioreactor proposed in this invention; Figure 2This is a schematic diagram of the primary separator structure of a denitrification bioreactor proposed in this invention; Figure 3 This is a schematic diagram of the secondary separator structure of a denitrification bioreactor proposed in this invention; Figure 4 This is a schematic diagram of the internal structure of the primary separator in a denitrification bioreactor proposed in this invention; Figure 5 This is a schematic diagram of the built-in primary separator of a denitrification bioreactor proposed in this invention.

[0019] In the diagram: 1 Reactor body, 2 Inlet water distribution system, 3 Overflow outlet tank, 4 Primary separator, 5 Secondary separator, 6 Circulation pump, 7 Floating sludge pump, 8 First inlet, 9 Sludge outlet, 10 Circulation connection port, 11 Motorized port, 12 First outlet, 13 Overflow port, 14 Breathing port, 15 Waste gas connection port, 16 Circulation port, 17 Outer cylinder, 18 Inner cylinder, 19 Swirl distributor, 20 Inlet tank, 21 Second outlet, 22 Floating sludge pipe, 25 Sedimentation module, 26 Sludge hopper, 27 Water distribution area, 28 Sedimentation area, 29 Inclined plate, 30 Top plate, 31 Side plate, 32 End plate one, 33 End plate two, 34 Second inlet, 35 Third outlet. Detailed Implementation

[0020] 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.

[0021] Reference Figures 1-5 A reactor body includes: reactor body 1, inlet water distribution system, primary separator, secondary separator, circulating pump, and sludge pump; The reactor body 1 is cylindrical or cuboid in shape, made of metal or reinforced concrete, with a diameter (or side length) of 3~20m and a height of 8~24m. The bottom of the side wall is provided with an inlet, a sludge outlet and a circulation outlet, the middle of the side wall is provided with a motor outlet, the upper part of the side wall is provided with an outlet, and the top is provided with a vent.

[0022] The water inlet distribution system 2 is installed at the bottom of the reactor. It adopts a perforated water distribution method with an opening diameter of 15~50mm. After the reactor inlet water flow, the circulating flow from the circulating pump and the recovered floating mud from the floating mud pump are combined, the water is evenly distributed to the bottom of the reactor body.

[0023] The primary separator is installed at the top, either outside or inside the reactor, to collect the mixture after the denitrification reaction and separate nitrogen and sludge.

[0024] The primary separator includes an outer cylinder, an inner cylinder, and a vortex distributor.

[0025] The upper part of the outer cylinder is cylindrical or prismatic, with water entering from the top; the lower part is conical or pyramidal, with the outlet at the bottom, and the effluent flows by gravity to the secondary separator. A vortex distributor is installed at the top of the outer cylinder, consisting of a ring of umbrella-shaped plates. The angle between the plates and the generatrix of the umbrella cone is 10-60°, with overlap between the plates and gaps allowing liquid to pass through. The vortex distributor disperses the water flow into droplets, increasing the gas-liquid contact area. Combined with the inertial collision of the droplets with the umbrella-shaped plates, it effectively removes free gas and air bubbles carried on the sludge surface. The inner cylinder is concentric with the outer cylinder, open at both ends, with its bottom connected to the outer cylinder and its top 200-800mm lower than the outer cylinder. As the water flows downwards between the outer and inner cylinders, the sludge that has not been degassed, being lighter, floats to the surface of the inner cylinder. The upper part of the inner cylinder is equipped with a sludge-floating pipe at an angle of 30-60° downwards, which is connected to a sludge-floating pump. The top of the primary separator has an air vent.

[0026] The surface load u of the first-stage separator is less than 0.5m. 3 / (m 2 .s).

[0027] A single reactor body can be equipped with one or more primary separators.

[0028] The secondary separator is installed at the bottom of the reactor body and is used for solid-liquid separation of the effluent from the primary separator. The pressure at the bottom of the reactor is equal to the sum of atmospheric pressure and liquid level pressure, which is higher than the pressure at the top of the reactor. According to Henry's Law, gas solubility is directly proportional to pressure. Nitrogen gas transforms from a gaseous state to a dissolved state, reducing the amount of gas in the mixed liquor and granular sludge, thus ensuring effective sedimentation and separation.

[0029] The secondary separator is fully enclosed and includes a sedimentation module and a sludge hopper. The sedimentation module has a top plate with an inlet connected to the outlet of the primary separator. The sedimentation module is divided into a distribution zone and a sedimentation zone. Influent flows downwards and is evenly distributed in the distribution zone, then flows upwards through the sedimentation zone. The sedimentation zone is equipped with inclined plates, with a length of 0.6–2 m, an inclination angle of 50–60°, and a spacing of 50–150 mm. The surface loading of the sedimentation zone is 0.2–0.75 m³ / s. 3 / (m 2 (h). Under gravity, the denitrifying sludge settles to the surface of the inclined plate and slides down the plate into the sludge hopper at the bottom. The clear liquid above the inclined plate flows out of the sedimentation module and exits the reactor by gravity through the effluent outlet on the side wall of the reactor. One to three sludge hoppers are located below the sedimentation module, running along the length of the reactor. The inclination angle of the sludge hoppers is 50 to 60 degrees. Each sludge hopper has a circulation port with an independent valve control, connected to a circulation pump.

[0030] One or more secondary separators can be installed at the bottom of the reactor.

[0031] The circulating pump is installed outside the reactor. The pump inlet is connected to the circulation port of the secondary separator, and the pump outlet is connected to the reactor inlet water distribution system to mix with the inlet water. The circulation backflow makes the reactor's upward flow velocity reach 2~8m / h, ensuring full contact between wastewater and denitrification sludge. It also provides the upward flow velocity and stirring energy required to ensure the mixing effect of the reactor, eliminating the need for a separate mechanical agitator and nitrification liquid return pump.

[0032] The sludge pump is installed outside the reactor. The pump inlet is connected to the sludge pipe of the primary separator. The pump outlet has two destinations: one is a sludge discharge pipe, which discharges the sludge to the sludge treatment system; the other is a sludge recovery pipe, which is connected to the reactor influent distribution system and mixes with the influent.

[0033] Example 1

[0034] like Figure 1 As shown, a denitrification bioreactor includes: a reactor body 1, an influent distribution system 2, an overflow effluent tank 3, a primary separator 4, a secondary separator 5, a circulation pump 6, and a sludge pump 7.

[0035] In this embodiment, the reactor body 1 is cylindrical in shape, with a carbon steel anti-corrosion structure, a diameter of 7.5m and a height of 15m. The bottom of the side wall is provided with a first water inlet 8, a sludge inlet 9 and a circulation connection port 10, the middle of the side wall is provided with a motor port 11, the upper part of the side wall is provided with a first water outlet 12 and an overflow port 13, and the top is provided with a vent 14 and an exhaust gas connection port 15.

[0036] The water inlet distribution system 2 is installed at the bottom of the reactor body 1. It adopts a perforated water distribution form with an opening diameter of 22mm. After the water inlet from the first water inlet 8 is combined with the circulating water delivered by the circulating pump 6 and the recovered floating mud delivered by the floating mud pump 7, it is evenly distributed to the bottom of the reactor body 1.

[0037] An overflow trough 3 is installed on the upper part of the reactor body 1 to collect the overflow water from the top of the reactor body 1. It adopts the form of an adjustable weir plate, and the end of the overflow trough 3 is connected to the overflow port 13 on the side wall of the reactor body 1.

[0038] The primary separator 4 is installed outside the reactor body 1 to collect the water, gas, and sludge mixture after the denitrification reaction and to separate the biogas and floating sludge, as shown in the attached diagram. Figure 2 As shown in (a) and (b).

[0039] The primary separator 4 includes: an outer cylinder 17, an inner cylinder 18, a vortex distributor 19, and an inlet tank 20.

[0040] The upper part of the outer cylinder 17 is cylindrical, with an inlet pipe and an inlet trough 20 on the side wall. The inlet pipe connects to the water from the reactor overflow port 13 and distributes it to the top of the cyclone distributor 19 through the inlet trough 20. The cyclone distributor 19 is composed of a ring of umbrella-shaped plates with an angle of 40° between the plates and the generatrix of the umbrella cone. The plates overlap and have gaps that allow liquid to pass through. The top of the cyclone distributor 19 has a vent that communicates with the top space of the outer cylinder. The top of the outer cylinder 17 has an exhaust port that is connected to the exhaust port 15 at the top of the reactor body 1. The lower part of the outer cylinder 17 is conical, with a second outlet 21 at the bottom, which is connected to the secondary separator 5 through the motor port 11 in the middle of the reactor side wall. The inner cylinder 18 is a cylinder concentric with the outer cylinder 17 and is used to collect floating sludge. The top opening of the inner cylinder is 600mm lower than that of the outer cylinder, and the bottom opening communicates with the outer cylinder 17. The inner cylinder 18 is equipped with a mud-floating pipe 22 at the upper part, which is angled downward at 45°. The mud-floating pipe 22 is connected to the mud-floating pump 7.

[0041] In this embodiment, a primary separator 4 is installed outside the reactor body 1. The outer cylinder 17 has a diameter of 800 mm, the inner cylinder has a diameter of 300 mm, and the total height is 1800 mm. The surface loading u = 0.007 m. 3 / (m 2 .s).

[0042] The secondary separator 5 is installed at the bottom of the reactor body 1 and is used to separate the denitrifying sludge in the effluent of the primary separator 4 by sedimentation, as shown in the attached diagram. Figure 3 As shown in (a), (b), and (c).

[0043] The secondary separator 5 is a fully enclosed type, consisting of an upper sedimentation module 25 and a lower sludge hopper 26. Inside the sedimentation module 25, a longitudinal partition divides it into a water distribution zone 27 and a sedimentation zone 28. The sedimentation zone is equipped with inclined plates 29, each 1.6m long, at a 55° angle, with a spacing of 100mm. The surface loading of the sedimentation zone is 0.5m³. 3 / (m 2 The sedimentation module 25 has a top plate 30 on top, with an inlet 34 on the top plate 30, which is connected to the second outlet 21 of the primary separator 4; there are two side plates 31 on the side, with an end plate 32 and 33 at each end, with an outlet 35 on the end plate 32, which is connected to the first outlet 12 on the upper side wall of the reactor body 1.

[0044] The sludge hopper 26 is located below the sedimentation module 25. In this embodiment, the secondary separator is equipped with two sludge hoppers with an inclination angle of 55°. The bottom of the sludge hopper 26 is provided with a circulation port 16, and each circulation port is connected to the circulation pump through an independent valve.

[0045] In this embodiment, a secondary separator 5 with external dimensions of 4900×2100×3800mm is installed inside the reactor body 1 and is fixed to the side wall of the reactor body 1 by means of lugs and support beams.

[0046] A circulating pump 6 is installed outside the reactor body 1. Its suction port is connected to the bottom circulation port 16 of the secondary separator 5, and its outlet is connected to the reactor inlet distribution system 2 to mix with the inlet water. The circulating flow returns to the reactor inlet, ensuring sufficient contact between the wastewater and the denitrifying sludge, while also providing the upward flow velocity and stirring energy required to ensure effective mixing in the reactor. In this embodiment, the rated flow rate of the circulating pump is 255 m³ / h. 3 / h, corresponding to a reactor upflow velocity of 6m / h.

[0047] The sludge pump 7 is installed outside the reactor body 1. The pump inlet is connected to the sludge pipe 22 of the primary separator 4, and the pump outlet is connected to the reactor inlet water distribution system 2 to mix with the inlet water. A bypass is provided at the pump outlet to discharge the remaining sludge to the sludge treatment system.

[0048] During use, the water entering the reactor body 1 is lifted by the water inlet pump, and after merging with the circulating flow from the circulating pump 6 and the recovered floating sludge from the floating sludge pump 7, it is evenly distributed to the bottom cross section of the reactor via the water inlet distribution system 2 at the bottom of the reactor body 1, and then flows upward through the denitrifying sludge bed, where the nitrates in the wastewater are converted into nitrogen by denitrifying bacteria. At the top of the reactor body 1, the denitrified mixture flows into the overflow effluent tank (3), and through the overflow port 13 into the primary separator 4 to separate the gas and floating sludge. The separated gas flows to the top of the reactor body 1 through the connecting pipe and is led out of the reactor through the breather port 14. The floating sludge is discharged as residual sludge, and the rest is returned to the influent distribution system 2 through the floating sludge pump 7. The effluent from the primary separator 4 flows by gravity through the pipe to the secondary separator 5 at the bottom of the reactor body 1. The secondary separator is a fully enclosed inclined plate sedimentation tank. The mud-water mixture enters from the top of the secondary separator 5, is distributed to the bottom of the sedimentation zone through the water distribution zone, and flows upward through the inclined plate sedimentation zone. The effluent after sludge separation flows out from the secondary separator and is discharged from the reactor body 1 through the first outlet 12. The denitrified sludge is collected in the sludge hopper 26 of the secondary separator 5 and is connected to the circulation pump 6 through the circulation port 16 together with the circulating flow, and returned to the influent distribution system 2.

[0049] Application Example 1 Example 1 was used to treat nitrate wastewater from the photovoltaic industry. The reactor was designed with an influent flow rate of 250 m³ / h. 3 / d, NO3 - -N concentration 1000 mg / L. Flocculent sludge was inoculated into the reactor. Treatment results are shown in Table 1. Table 1. Actual operating results of Example 1

[0050] In this application example, the reactor body maintained a TN removal rate of over 83%, and the SS in the reactor effluent was below 200 mg / L, which is very low for a flocculent sludge denitrification system, reflecting a superior sludge separation effect. At the same time, there was no floating sludge on the reactor surface, the operation was stable, and it had good resistance to shock loads.

[0051] Example 2

[0052] like Figure 4 As shown, a denitrification bioreactor includes: reactor body 1, influent distribution system 2, primary separator 4, secondary separator 5, circulation pump 6, and sludge pump 7.

[0053] In this embodiment, the reactor body 1 is a cuboid with a reinforced concrete structure, 10m long, 8m wide, and 12m high. The bottom of the side wall is provided with an inlet 8, a sludge outlet 9, and a circulation connection 10. The middle of the side wall is provided with a motor outlet 11. The upper part of the side wall is provided with a first outlet 12. The top is provided with a vent 14.

[0054] The water inlet distribution system 2 is installed at the bottom of the reactor body 1. It adopts a perforated water distribution form with an opening diameter of 26mm. After the water inlet from the inlet 8 is combined with the circulating water delivered by the circulating pump 6 and the recovered floating mud delivered by the floating mud pump 7, it is evenly distributed to the bottom of the reactor body 1.

[0055] The built-in primary separator 4 is installed on the upper part of the reactor body 1 to collect the water, gas, and sludge mixture after the denitrification reaction and to separate the nitrogen and floating sludge, as shown in the attached diagram. Figure 5 As shown in (a) and (b).

[0056] The primary separator 4 includes an outer cylinder 17, an inner cylinder 18, and a vortex distributor 19.

[0057] The outer cylinder 17 has a cylindrical upper part with an overflow inlet at the top and a conical lower part with an outlet 21 at the bottom. A vortex distributor 19 is installed inside the outer cylinder 17 and consists of a ring of umbrella-shaped plates. The angle between the plates and the generatrix of the umbrella cone is 45°. The plates overlap and have gaps allowing liquid to pass through. The top of the vortex distributor 19 has a vent. The inner cylinder 18 is a cylinder concentric with the outer cylinder 17, with its top opening 400mm lower than the outer cylinder and its bottom opening communicating with the outer cylinder 17. A sludge-floating pipe is installed at the top of the inner cylinder 18, angled downwards at 45°. The sludge-floating pipe passes through the outer cylinder and connects to a sludge-floating port in the middle of the side wall of the reactor body 1.

[0058] In this embodiment, four primary separators 4 are installed inside the reactor body 1. The outer cylinder has a diameter of 800 mm, the inner cylinder has a diameter of 300 mm, and the total height is 1800 mm. The top surface of the outer cylinder is flush with the liquid level. The surface loading u = 0.013 m.3 / (m 2 .s).

[0059] The secondary separator 5 is installed at the bottom of the reactor body 1 and is used to separate the denitrifying sludge in the effluent of the primary separator 4 by sedimentation, as shown in the attached diagram. Figure 3 As shown in (a), (b), and (c).

[0060] In this embodiment, the external dimensions and internal structure of the secondary separator 5 are the same as in Embodiment 1. A total of four secondary separators 5, each with external dimensions of 5700×2000×4200mm, are installed inside the reactor body 1 and fixed to the bottom plate of the reactor body 1 by supports. The surface loading of the sedimentation zone of the secondary separator is 0.48m². 3 / (m 2 .h).

[0061] A circulating pump 6 is installed outside the reactor body 1. Its suction port is connected to the bottom circulation port 16 of the secondary separator 5, and its outlet is connected to the reactor inlet distribution system 2 to mix with the inlet water. The circulating flow returns to the reactor inlet, ensuring sufficient contact between the wastewater and the denitrifying sludge, while also providing the necessary upward flow velocity and stirring energy to guarantee the reactor's mixing effect. In this embodiment, one circulating pump with a rated flow rate of 220 m³ / h is used. 3 / h, corresponding to a reactor upflow velocity of 4m / h.

[0062] The sludge pump 7 is installed outside the reactor body 1. Its suction port is connected to the sludge pipe of the primary separator 4, and its outlet is connected to the reactor inlet water distribution system 2 to mix with the inlet water. A bypass is provided at the pump outlet to discharge the remaining sludge to the sludge treatment system. In this embodiment, one sludge pump is used, with a rated flow rate of 10 m³ / h. 3 / h.

[0063] During use, the water entering the reactor body 1 is lifted by the water inlet pump, and after merging with the circulating flow from the circulating pump 6 and the recovered floating sludge from the floating sludge pump 7, it is evenly distributed to the bottom cross section of the reactor via the water inlet distribution system 2 at the bottom of the reactor body 1, and then flows upward through the denitrifying sludge bed, where the nitrates in the wastewater are converted into nitrogen by denitrifying bacteria. At the top of reactor body 1, the denitrified mixture overflows into primary separator 4 to separate the gas and sludge. The separated gas collects at the top of reactor body 1 and exits the reactor through breather 14. The sludge is connected to sludge pump 7 through motor port 11 on the side wall of the reactor. After the gas is discharged by the shearing action of the pump, part of it is discharged as residual sludge, and the rest is returned to the influent distribution system 2 through sludge pump 7. The effluent from primary separator 4 flows by gravity through pipe to secondary separator 5 at the bottom of reactor body 1. It is a fully enclosed inclined plate sedimentation tank. The mud-water mixture enters from the top of secondary separator 5, is distributed to the bottom of sedimentation zone through water distribution zone, and flows upward through inclined plate sedimentation zone. The effluent after sludge separation flows out from secondary separator and is discharged from reactor body 1 through first outlet 12. The denitrified sludge is collected in sludge hopper 26 of secondary separator 5 and is connected to circulation pump 6 through circulation port 16 along with the circulating flow, returning to influent distribution system 2.

[0064] Application Example 2 Example 2 was used to treat nitrate wastewater from the electronics industry. The reactor was designed with an influent flow rate of 360 m³ / h. 3 / d, NO3 - -N concentration 870 mg / L. Flocculent sludge was inoculated into the reactor. Treatment results are shown in Table 2. Table 2. Actual operating results of Example 2

[0065] As described above, in this invention, wastewater is pumped up by an influent pump and merged with the circulating flow from the circulation pump and the recovered floating sludge from the floating sludge pump. It is then evenly distributed to the bottom of the reactor via an influent distribution system, and flows upward through the denitrifying sludge bed. Nitrates in the wastewater are converted into nitrogen by denitrifying bacteria. At the top of the reactor, the denitrified mixture overflows into a primary separator, effectively separating the gas and floating sludge. The separated gas is led out of the reactor through a vent at the top, while the floating sludge, after being sheared by the floating sludge pump to expel gas, has a portion discharged as residual sludge, and the remainder returned to the reactor to mix with the influent. The effluent from the primary separator flows by gravity through a pipe to the secondary separator at the bottom of the reactor, which is a fully enclosed inclined plate settler. The sludge-water mixture flows sequentially through the distribution zone and the sedimentation zone. The denitrifying sludge is separated by gravity sedimentation, and the clear effluent is discharged from the reactor through an outlet pipe. The separated sludge and the circulating flow are mixed with the reactor influent via a circulation pump, ensuring the required upward flow velocity and stirring energy for the reactor's mixing effect.

[0066] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention, all of which fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A denitrification bioreactor, comprising a reactor body (1), an influent distribution system (2), a primary separator (4), a secondary separator (5), a circulation pump (6), and a sludge pump (7), characterized in that, The reactor body (1) has a first inlet (8), a sludge inlet (9) and a circulation connection inlet (10) at the bottom of the side wall, a motor inlet (11) in the middle of the side wall, a first outlet (12) at the top of the side wall, and a vent (14) at the top. The water inlet distribution system (2) is installed at the bottom of the reactor body (1). It adopts a perforated water distribution form with an opening diameter of 15~50mm. After the reactor inlet water flow, the circulating flow from the circulating pump (6), and the recovered floating mud from the floating mud pump (7) are combined, the water is evenly distributed to the bottom of the reactor body (1). The primary separator (4) is located at the top of the reactor body (1), either outside or inside the reactor, and is used to collect the mixture after the denitrification reaction and separate nitrogen and sludge from it. The primary separator (4) includes an outer cylinder (17), an inner cylinder (18), and a vortex distributor (19). The upper part of the outer cylinder (17) is cylindrical or prismatic, and a second inlet is provided at the upper part. The lower part of the outer cylinder (17) is conical or pyramidal, and a second outlet (21) is provided at the bottom. The water flows by gravity to the secondary separator (5). The side wall of the primary separator (4) is also provided with an inlet trough (20) and a downwardly inclined sludge pipe (22). The outer cylinder (17) is also provided with a vortex water distributor (19) at the top. The vortex water distributor (19) is higher than the inner cylinder (18) and is located between the inner cylinder (18) and the outer cylinder (17). The vortex water distributor (19) is composed of a ring of umbrella-shaped plates. The angle between the plates and the generatrix of the umbrella cone is 10~60°. The plates overlap and have gaps that allow liquid to pass through. The vortex water distributor (19) makes the water flow splash and disperse into droplets. The inner cylinder (18) is concentric with the outer cylinder (17), with open ends. The bottom end is connected to the outer cylinder (17), and the top end is 200~800mm lower than the outer cylinder (17). The upper part of the inner cylinder (18) is provided with a mud-floating pipe at an angle of 30~60° downward. The mud-floating pipe is connected to the mud-floating pump (7). The top of the primary separator (4) has a vent hole. The secondary separator (5) is installed at the bottom of the reactor body (1). The secondary separator (5) is fully enclosed and includes a sedimentation module (25) and a sludge hopper (26).

2. The denitrification bioreactor according to claim 1, characterized in that, The reactor body (1) is cylindrical or cuboid in shape, made of metal or reinforced concrete, with a diameter or side length of 3~20m and a height of 8~24m.

3. A denitrification bioreactor according to claim 1, characterized in that, When the primary separator (4) is installed outside the reactor body (1), an overflow outlet trough (3) is installed on the upper part of the reactor body (1) to collect the overflow water from the top of the reactor body (1). The overflow outlet trough (3) is in the form of an adjustable weir plate. The end of the overflow outlet trough (3) is connected to the overflow port (13) on the side wall of the reactor body (1). The top of the reactor body (1) is also provided with an exhaust gas connection port (15).

4. A denitrification bioreactor according to claim 1, characterized in that, The surface load u of the primary separator (4) is less than 0.5m. 3 / (m 2 .s).

5. A denitrification bioreactor according to claim 1 or 3, characterized in that, Inside the sedimentation module (25), a longitudinal partition divides the sedimentation module (25) into a water distribution zone (27) and a sedimentation zone (28). The sedimentation zone (28) is equipped with inclined plates (29), the length of which is 0.6~2m, the inclination angle of which is 50~60°, the spacing of which is 50~150mm, and the surface load of the sedimentation zone (28) is 0.2~0.75m. 3 / (m 2 .h); The clear liquid above the inclined plate (29) flows out of the sedimentation module (25) and flows out of the reactor body (1) by itself through the water outlet on the side wall of the reactor body (1); The sedimentation module (25) has a top plate (30) on top, and a second inlet (34) is provided on the top plate (30), which is connected to the second outlet (21) of the first stage separator (4); two side plates (31) are provided on the side, and there is an end plate one (32) and an end plate two (33) at each end. The end plate one (32) is provided with a third outlet (35), which is connected to the first outlet (12) on the upper side wall of the reactor body (1).

6. A denitrification bioreactor according to claim 5, characterized in that, The sludge hopper (26) is located below the sedimentation module (25). There are 1 to 3 sludge hoppers (26) along the length direction. The inclination angle of the sludge hopper (26) is 50 to 60°. Each sludge hopper (26) is equipped with a circulation port (16) with an independent valve control and connected to the circulation pump (6).

7. A denitrification bioreactor according to claim 1, characterized in that, One or more secondary separators (5) can be installed at the bottom of the reactor body (1).

8. A denitrification bioreactor according to claim 1, characterized in that, The circulating pump (6) is installed outside the reactor body (1). The pump inlet is connected to the circulation port (16) of the secondary separator (5), and the pump outlet is connected to the water inlet distribution system (2) of the reactor body (1) to mix with the inlet water.

9. A denitrification bioreactor according to claim 1, characterized in that, The sludge pump (7) is installed outside the reactor body (1). The pump inlet is connected to the sludge pipe (22) of the primary separator (4). The pump outlet has two destinations: one is a sludge discharge pipe, which discharges the sludge to the sludge treatment system; the other is a sludge recovery pipe, which is connected to the water inlet distribution system (2) of the reactor body (1) and mixes with the water inlet.

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