Denitrification bioreactor

Abstract

The invention discloses a denitrification bioreactor, which comprises a reactor body, a water inlet distribution system, a primary separator, a secondary separator, a circulating pump and a float sludge pump, the bottom of the side wall of the reactor body is provided with a first water inlet, a sludge port and a circulating connection port, the middle of the side wall is provided with a maneuvering port, the upper part of the side wall is provided with a first water outlet, and the top is provided with a breathing port; the water inlet distribution system is mounted at the bottom of the reactor body and adopts a perforated water distribution mode, and the diameter of an opening is about mm. Multiple measures are adopted to strengthen the degassing effect, the gas-liquid contact area is increased, free gas can escape from water to a gas phase, the gas is converted into a dissolved state by utilizing higher pressure at the lower part of the reactor, and the gas carrying amount of mixed liquid entering a precipitation module is reduced. Degassing is the premise of sludge settling, and enhanced degassing can improve the sludge settling speed from the source and ensure the sludge-water separation effect.

Description

Technical Field

[0001] The invention relates to the field of denitrification biotechnology, in particular to a denitrification bioreactor. Background Art

[0002] Denitrification is the final step of biological denitrification of wastewater. Its principle is to use denitrifying bacteria to reduce nitrates to nitrogen gas and remove them from wastewater. For common ammonia nitrogen wastewater, denitrification treatment must be combined with nitrification treatment to form a nitrification / denitrification system to achieve biological denitrification; the application of independent reactor bodies is not very common, but it still has practical significance in the following cases:

[0003] 1. For wastewater in which nitrogen in the incoming water exists in the form of nitrate, only denitrification treatment is required;

[0004] 2. The reactor usually adopts a larger height-to-diameter ratio, which saves floor space by increasing the water depth, and is a better choice under the condition of limited land use;

[0005] 3. By integrating mud-water separation, sludge return and nitrification liquid return in the reactor, the process flow is simplified and the device is made more optimized and compact.

[0006] In practical applications, the main problems that denitrification bioreactors need to overcome are the sludge running and floating sludge caused by sludge gasification. The reasons are as follows:

[0007] 1. Reaction mechanism factors: The final product of denitrification is nitrogen. Nitrogen bubbles are adsorbed on the surface or inside of the sludge, causing the sludge to be light, easy to float, and poor mud-water separation effect;

[0008] 2. Reactor structure factors: The reactor body generally has water inlet at the bottom and outlet at the top. During the upward flow of wastewater, the water pressure continues to decrease. According to Henry's law (p = H x), when the pressure p decreases, the solubility of the gas 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 float, which is similar to the principle of a flotation machine;

[0009] 3. Separator structure factors: The three-phase separator used in the existing reactor body is generally a hydraulic baffle degassing, that is, the mixed liquid is deflected downward by setting a baffle, and the bubble density is small and it is difficult to follow the water flow downward, thereby achieving gas-water separation; this separator has a good effect on separating free bubbles, but it is difficult to separate bubbles combined with sludge, and the sludge with gas is also blocked by the baffle, accumulating on the reactor liquid surface to form a floating mud layer;

[0010] 4. Limitations of existing measures: Some existing reactor bodies have taken measures to eliminate bubbles and floating mud, such as hydraulic spraying, hydraulic spraying + defoaming agent, aeration disturbance defoaming, etc., but these measures also have obvious disadvantages, such as the large amount of water used for hydraulic spraying, the toxicity of defoaming agents to microorganisms and the impact on the subsequent water reuse membrane, and the common proteins, oils, and surfactants in wastewater will make the aeration defoaming effect worse, etc. Moreover, these measures only temporarily break up the floating mud but do not discharge it. As mentioned above, since the cause of the floating mud is the inherent factor of the reactor body, the floating mud will continue to be produced, resulting in a gradual decline in the effectiveness of the above measures.

[0011] As mentioned above, we have designed a denitrification bioreactor to solve the above problems. Summary of the invention

[0012] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a denitrification bioreactor.

[0013] In order to achieve the above object, the present invention adopts the following technical solutions:

[0014] A denitrification bioreactor comprises a reactor body, a water inlet distribution system, a primary separator, a secondary separator, a circulation pump, and a floating mud pump.

[0015] The bottom of the side wall of the reactor body is provided with a first water inlet, a sludge inlet and a circulation 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, and the top is provided with a breathing port;

[0016] The water inlet distribution system is installed at the bottom of the reactor body, adopts a perforated water distribution form, and the opening diameter is ~mm. After the reactor inlet water flow is merged with the circulating flow from the circulating pump and the recovered floating mud from the floating mud pump, it is evenly distributed to the bottom of the reactor body;

[0017] The primary separator is located at the upper part of the reactor body, and is arranged outside the reactor or inside the reactor, and is used to collect the mixed liquid after the denitrification reaction and separate the nitrogen and floating mud therein;

[0018] The primary separator comprises an outer cylinder, an inner cylinder and a cyclone water distributor, the upper portion of the outer cylinder is cylindrical or prismatic, and is provided with a second water inlet, the lower portion of the outer cylinder is conical or pyramidal, and the bottom end is a second water outlet, and the outlet water flows to the secondary separator by gravity, and a water inlet trough and a sludge pipe inclined downward are also provided on the side wall of the primary separator;

[0019] The upper part of the outer cylinder is also provided with a cyclone water distributor, which is composed of a circle of umbrella-shaped plates, the angle between the plates and the umbrella-shaped cone generatrix is ​​10-60 degrees, the plates overlap, and there are gaps allowing liquid to pass through, and the cyclone water distributor makes the water flow splash and disperse into droplets;

[0020] The inner tube is concentric with the outer tube, with both ends open, the bottom end communicates with the outer tube, and the top end is 17200-800mm lower than the outer tube; a floating mud pipe is arranged on the upper part of the inner tube, with an angle of 30-60° downward, the floating mud pipe is connected to the floating mud pump, and a vent hole is arranged on the top of the first-stage separator;

[0021] The secondary separator is installed at the bottom of the reactor body.

[0022] Preferably, the reactor body is cylindrical or rectangular in shape, made of metal structure or reinforced concrete structure, with one of the diameter or side length set to 3 to 20 m, and the height 8 to 24 m.

[0023] Preferably, when the primary separator is installed outside the reactor body, an overflow water trough is installed on the upper part of the reactor body to collect overflow water from the top of the reactor body. An adjustable weir plate is adopted, and the end of the overflow water trough is connected to the overflow port on the side wall of the reactor body. The top of the reactor body is also provided with a waste gas connecting port.

[0024] Preferably, the surface load u of the primary separator is less than 0.5 m 3 / (m 2 .s).

[0025] Preferably, the secondary separator is a fully enclosed type, comprising a sedimentation module and a sludge hopper;

[0026] The top of the sedimentation module is provided with a top plate, on which a third water inlet is arranged, connected to the second water outlet of the primary separator;

[0027] In the sedimentation module, a longitudinal partition divides the sedimentation module into a water distribution area and a sedimentation area. The sedimentation area is provided with an inclined plate (length 0.6-2m, inclined plate inclination angle 50-60°, inclined plate spacing 50-150mm, sedimentation area surface load 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 outlet pipe on the side wall of the reactor body;

[0028] The precipitation module has a top plate on the top, on which a second water inlet is arranged, which is connected to the second water outlet of the first-stage separator; two side plates are arranged on the side, with an end plate 1 and an end plate 2 at each end, wherein a third water outlet is arranged on the end plate 1, which is connected to the first water outlet on the upper part of the side wall of the reactor body.

[0029] Preferably, the sludge hopper is below the sedimentation module, and 1 to 2 sludge hoppers are arranged along the length direction. The inclination angle of the sludge hopper is 1 to 2 degrees. Each sludge hopper is provided with a circulation port, which is controlled by an independent valve and connected to a circulation pump.

[0030] Preferably, one or more secondary separators may be installed at the bottom of the reactor body.

[0031] Preferably, the circulation pump is installed outside the reactor body, the pump suction port is connected to the circulation port of the secondary separator, and the pump outlet is connected to the water inlet distribution system of the reactor body to mix with the inlet water.

[0032] Preferably, the floating mud pump is installed outside the reactor body, the pump suction port is connected to the floating mud pipe of the primary separator, and the pump outlet has two destinations: one is a mud discharge pipe, which discharges the floating mud to the sludge treatment system; the other is a floating mud recovery pipe, which is connected to the water inlet distribution system of the reactor body and mixed with the inlet water.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The reactor adopts overflow discharge mode. After the floating sludge is generated, it will flow into the primary separator together with the water flow, and will not be retained in the reactor to form a floating sludge layer;

[0035] (2) Multiple measures are adopted to enhance the degassing effect: First, in the primary separator, the cyclone water distributor disperses the incoming water into droplets, increasing the gas-liquid contact area and facilitating the escape of free gas 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 bubbles carried on the sludge surface; third, for the bubbles in the sludge that have not been removed in the first two steps, the characteristics of the gas-carrying sludge with low density and easy floating are used to make it gather in the inner cylinder, and then the gas is discharged through the shearing action of the floating mud 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 in the mixed liquid entering the sedimentation module. Degassing is a prerequisite for sludge sedimentation. Strengthening degassing can increase the sludge sedimentation rate from the source and ensure the mud-water separation effect;

[0036] (3) The floating sludge collected in the inner tube can be returned to the reactor or discharged from the system as needed, combining the residual sludge discharge with the floating sludge removal, killing two birds with one stone, thereby avoiding the accumulation of floating sludge and keeping the floating sludge amount in a balanced and controllable state;

[0037] (4) The secondary separator adopts inclined plate sedimentation, which has a compact structure and occupies a small area.

[0038] (5) The bottom flow of the secondary separator is returned to the reactor inlet water through a circulation pump. The hydraulic agitation provided by the circulation flow ensures the rising flow rate and stirring energy required for the mixing effect of the reactor, replacing mechanical agitation and avoiding the maintenance inconvenience caused by the submerged agitator.

[0039] (6) The circulation flow comes from the bottom of the water distribution area and does not pass through the inclined plate sedimentation area. Therefore, the circulation flow can be adjusted according to process needs without affecting the sedimentation effect of the secondary separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the structure of a denitrification bioreactor proposed by the present invention;

[0041] Figure 2 This is a schematic diagram of the structure of a primary separator of a denitrification bioreactor proposed by the present invention;

[0042] Figure 3 This is a schematic diagram of the structure of a secondary separator of a denitrification bioreactor proposed by the present invention;

[0043] Figure 4 This is a schematic diagram of the structure of a primary separator of a denitrification bioreactor proposed by the present invention;

[0044] Figure 5 This is a schematic structural diagram of a built-in primary separator of a denitrification bioreactor proposed by the present invention.

[0045] In the figure: 1 reactor body, 2 water inlet distribution system, 3 overflow outlet trough, 4 primary separator, 5 secondary separator (5), 6 circulation pump, 7 floating mud pump, 8 first water inlet, 9 sludge outlet, 10 circulation connection port, 11 motor port, 12 first water outlet, 13 overflow port, 14 breathing port, 15 exhaust gas connection port, 16 circulation port, 17 outer cylinder, 18 inner cylinder, 19 cyclone water distributor, 20 water inlet trough, 21 second water outlet, 22 floating mud 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 1, 33 end plate 2, 34 second water inlet, 35 third water outlet. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0047] Reference Figure 1-Figure 5 , a reactor body, comprising: a reactor body (1), a water inlet distribution system, a primary separator, a secondary separator, a circulation pump, and a floating mud pump;

[0048] The reactor body (1) is cylindrical or rectangular in shape, made of metal structure or reinforced concrete structure, with a diameter (or side length) of 3 to 20 m and a height of 8 to 24 m. A water inlet, a sludge inlet and a circulation inlet are provided at the bottom of the side wall, a motor port is provided in the middle of the side wall, a water outlet is provided at the top of the side wall, and a breathing port is provided at the top.

[0049] The inlet water distribution system 2 is installed at the bottom of the reactor and adopts a perforated water distribution form with a hole diameter of 15 to 50 mm. After the reactor inlet water flow is merged with the circulating flow from the circulating pump and the recovered floating mud from the floating mud pump, it is evenly distributed to the bottom of the reactor body.

[0050] The primary separator is installed at the upper part, and can be located outside the reactor or inside the reactor, and is used to collect the mixed liquid after the denitrification reaction and separate the nitrogen and floating mud therein.

[0051] The first-stage separator includes: an outer cylinder, an inner cylinder and a cyclone water distributor.

[0052] The upper part of the outer cylinder is cylindrical or prismatic, and water enters from the upper part; the lower part is conical or pyramidal, and the bottom end is the water outlet, and the water flows to the secondary separator by gravity; a cyclone water distributor is set on the upper part of the outer cylinder, which is composed of a circle of umbrella-shaped plates, and the angle between the plates and the umbrella-shaped cone generatrix is ​​10-60°. There is overlap between the plates, and there are gaps that allow liquid to pass through. The cyclone water distributor makes the water flow splash and disperse into droplets, increasing the gas-liquid contact area, and the inertial collision between the droplets and the umbrella-shaped plates can effectively remove free gas and bubbles carried on the sludge surface. The inner cylinder is concentric with the outer cylinder, with openings at both ends, the bottom end is connected to the outer cylinder, and the top end is 200-800mm lower than the outer cylinder. During the downward flow of water between the outer cylinder and the inner cylinder, the sludge that has not been degassed will float up and gather on the surface of the inner cylinder due to its lighter specific gravity. A floating mud pipe is arranged on the upper part of the inner tube, with an angle of 30 to 60 degrees downward, and the floating mud pipe is connected to the floating mud pump. There is a vent at the top of the first-stage separator.

[0053] The surface load of the first-stage separator u<0.5m 3 / (m 2 .s).

[0054] A single reactor body can be equipped with one or more primary separators.

[0055] The secondary separator is installed at the bottom of the reactor body to separate the solid and liquid from the effluent of the primary separator. The pressure at the bottom of the reactor is equal to the superposition 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 proportional to pressure. Nitrogen is converted from gaseous state to dissolved state, and the amount of gas in the mixed liquid and granular sludge decreases, thus ensuring the sedimentation separation effect.

[0056] The secondary separator is a fully enclosed type, including a sedimentation module and a sludge hopper. There is a top plate on the top of the sedimentation module, and a water inlet is set on the top plate, which is connected to the water outlet of the primary separator; the sedimentation module is divided into a water distribution area and a sedimentation area. The incoming water flows downward in the water distribution area and is evenly distributed, and then turns upward to pass through the sedimentation area. The sedimentation area is equipped with an inclined plate with a length of 0.6 to 2m, an inclination angle of 50 to 60°, a spacing of 50 to 150mm, and a surface load of 0.2 to 0.75m 3 / (m 2 .h). The denitrification sludge settles to the surface of the inclined plate under the action of gravity, and slides down the inclined plate into the bottom sludge hopper. The clear liquid above the inclined plate flows out of the sedimentation module and flows out of the reactor through the outlet pipe on the side wall of the reactor. The sludge hopper is below the sedimentation module. 1 to 3 sludge hoppers are set along the length direction. The inclination angle of the sludge hopper is 50 to 60 degrees. Each sludge hopper is equipped with a circulation port, which is controlled by an independent valve and connected to the circulation pump.

[0057] One or more secondary separators can be installed at the bottom of the reactor.

[0058] The circulation pump is installed outside the reactor, the pump suction port is connected to the circulation port of the secondary separator, and the pump outlet is connected to the reactor water inlet distribution system to mix with the inlet water. The circulation reflux makes the reactor's upward flow rate reach 2 to 8 m / h, ensuring sufficient contact between the wastewater and the denitrification sludge. At the same time, it also provides the upward flow rate and stirring energy required to ensure the mixing effect of the reactor, without the need for a separate mechanical agitator and nitrification liquid reflux pump.

[0059] The floating mud pump is installed outside the reactor, and the pump suction port is connected to the floating mud pipe of the first-stage separator. The pump outlet has two destinations: one is the mud discharge pipe, which discharges the floating mud to the sludge treatment system; the other is the floating mud recovery pipe, which is connected to the reactor water inlet distribution system and mixed with the inlet water.

[0060] Example 1

[0061] like Figure 1 As shown, a denitrification bioreactor comprises: a reactor body 1, a water inlet distribution system 2, an overflow water tank 3, a primary separator 4, a secondary separator 5, a circulation pump 6, and a floating mud pump 7.

[0062] In this embodiment, the reactor body 1 is cylindrical in shape, with a carbon steel anti-corrosion structure, a diameter of 7.5m, a height of 15m, a first water inlet 8, a sludge outlet 9 and a circulation connection port 10 at the bottom of the side wall, a motor port 11 in the middle of the side wall, a first water outlet 12 and an overflow port 13 at the upper part of the side wall, and a breathing port 14 and an exhaust gas connection port 15 at the top.

[0063] The water inlet distribution system 2 is installed at the bottom of the reactor body 1 and adopts a perforated water distribution form with a hole diameter of 22 mm. After the inlet water flow from the first water inlet 8 is merged with the circulating water flow 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.

[0064] The overflow water tank 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 water tank 3 adopts an adjustable weir plate. The end of the overflow water tank 3 is connected to the overflow port 13 on the side wall of the reactor body 1 .

[0065] The primary separator 4 is installed outside the reactor body 1 and is used to collect the water, gas and mud mixture after the denitrification reaction and separate the biogas and floating mud therein. Figure 2 As shown in (a) and (b).

[0066] The primary separator 4 comprises an outer cylinder 17 , an inner cylinder 18 , a cyclone water distributor 19 and a water inlet tank 20 .

[0067] The upper part of the outer cylinder 17 is cylindrical, and there are a water inlet pipe 21 and a water inlet groove 20 on the side wall. The water inlet pipe 21 is connected to the water from the overflow port 13 of the reactor, and is distributed to the top of the cyclone water distributor 19 through the water inlet groove 20; the cyclone water distributor 19 is composed of a circle of umbrella-shaped plates, the angle between the plates and the umbrella cone generatrix is ​​40°, there is overlap between the plates, and there is a gap allowing liquid to pass through, and the top of the cyclone water distributor 19 is provided with a vent, which is connected to the top space of the outer cylinder; the top of the outer cylinder 17 is provided with an exhaust port, which is connected to the exhaust gas connection port 15 at the top of the reactor body 1; the lower part of the outer cylinder 17 is conical, and a second water outlet 21 is arranged 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 cylindrical concentric with the outer cylinder 17, which is used to collect floating mud, the top opening of the inner cylinder is 600mm lower than the outer cylinder, and the bottom opening is connected to the outer cylinder 17. A floating mud pipe 22 is provided at the upper part of the inner tube 18 at an angle of 45° downward, and the floating mud pipe 22 is connected to the floating mud pump 7 .

[0068] In this embodiment, a primary separator 4 is installed outside the reactor body 1. The outer cylinder 17 has a diameter of 800 mm, an inner cylinder has a diameter of 300 mm, and a total height of 1800 mm. Surface load u = 0.007 m 3 / (m 2 .s).

[0069] The secondary separator 5 is installed at the bottom of the reactor body 1 and is used to precipitate and separate the denitrification sludge in the effluent of the primary separator 4. Figure 3 As shown in (a), (b) and (c).

[0070] The secondary separator 5 is a fully enclosed type, consisting of an upper sedimentation module 25 and a lower sludge hopper 26. In the sedimentation module 25, a longitudinal partition 32 divides the sedimentation module 25 into a water distribution area 27 and a sedimentation area 28. The sedimentation area is provided with an inclined plate 29 with a length of 1.6m, an inclined plate angle of 55°, an inclined plate spacing of 100mm, and a surface load of 0.5m 3 / (m 2 .h). The top of the sedimentation module 25 is provided with a top plate 30, on which a water inlet 34 is arranged, which is connected to the second water outlet 21 of the primary separator 4; the side is provided with two side plates 31, and the two ends are provided with an end plate 32 and 33 respectively, wherein the end plate 32 is provided with a water outlet 35, which is connected to the first water outlet 12 at the upper part of the side wall of the reactor body 1.

[0071] The sludge hopper 26 is below the sedimentation module 25. In this embodiment, the secondary separator is provided with two sludge hoppers, and the inclination angle of the sludge hopper is 55°. A circulation port 16 is provided at the bottom of the sludge hopper 26, and each circulation port is connected to a circulation pump through an independent valve control.

[0072] In this embodiment, a secondary separator 5 is installed in the reactor body 1, with an outer dimension of 4900×2100×3800 mm, and is fixed to the side wall of the reactor body 1 through ear seats and support beams.

[0073] The circulation pump 6 is installed outside the reactor body 1, the pump suction port is connected to the circulation port 16 at the bottom of the secondary separator 5, and the pump outlet is connected to the reactor inlet water distribution system 2 to mix with the inlet water. The circulation flow returns to the reactor inlet water, ensuring sufficient contact between the wastewater and the denitrification sludge, and also provides the rising flow rate and stirring energy required to ensure the mixing effect of the reactor. In this embodiment, the rated flow rate of the circulation pump is 255m 3 / h, and the corresponding reactor rising velocity is 6m / h.

[0074] The floating mud pump 7 is installed outside the reactor body 1, the pump suction port is connected to the floating mud 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 set at the pump outlet to discharge the remaining sludge to the sludge treatment system.

[0075] When in use, the influent of the reactor body 1 is lifted by the influent pump, and after merging with the circulating flow from the circulating pump 6 and the recovered sludge from the sludge pump 7, it is evenly distributed to the bottom cross section of the reactor through the influent distribution system 2 at the bottom of the reactor body 1, and then flows upward through the denitrifying sludge bed, and the nitrate in the wastewater is converted into nitrogen by the denitrifying bacteria. At the top of the reactor body 1, the mixed liquid after denitrification treatment flows into the overflow outlet tank (3), and flows into the primary separator 4 through the overflow port 13 to separate the gas and floating sludge therein. 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 breathing port 14. The floating sludge part is discharged as residual sludge, and the rest is returned to the water inlet distribution system 2 through the floating sludge pump 7; the effluent of the primary separator 4 flows through the pipeline to the secondary separator 5 at the bottom of the reactor body 1, which is in the form of a fully enclosed inclined plate sedimentation tank. The mud-water mixed liquid enters from the top of the secondary separator 5, is distributed to the bottom of the sedimentation area through the water distribution area, and flows upward through the inclined plate sedimentation area. The effluent after the sludge is separated flows out of 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 circulation flow, and returns to the water inlet distribution system 2.

[0076] Application Example 1

[0077] Example 1 was used to treat nitrate wastewater from a photovoltaic industry. The reactor was designed to have an inlet flow rate of 250 m 3 / d,NO 3 - -N concentration is 1000mg / L. Flocculent sludge is inoculated in the reactor. The treatment effect is shown in Table 1:

[0078] Table 1. Actual operation results of Example 1

[0079]

[0080]

[0081] In this application example, the reactor body maintained a TN removal rate of more than 83%, and the reactor effluent SS was below 200 mg / L, which is very low for a flocculent sludge denitrification system, reflecting the superior sludge separation effect. At the same time, there was no floating sludge on the reactor liquid surface, the operation effect was stable, and it had good shock load resistance.

[0082] Example 2

[0083] like Figure 4 As shown, a denitrification bioreactor comprises: a reactor body 1, a water inlet distribution system 2, a primary separator 4, a secondary separator 5, a circulation pump 6, and a floating mud pump 7.

[0084] In this embodiment, the reactor body 1 is a rectangular parallelepiped with a steel concrete structure, 10 m long, 8 m wide and 12 m high, with a water inlet 8, a sludge outlet 9 and a circulation connection port 10 at the bottom of the side wall, a motor port 11 in the middle of the side wall, a first water outlet 12 at the upper part of the side wall and a breathing port 14 at the top.

[0085] The water inlet distribution system 2 is installed at the bottom of the reactor body 1 and adopts a perforated water distribution form with a hole diameter of 26 mm. After the inlet water flow from the water inlet 8 is merged with the circulating water flow 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.

[0086] The built-in primary separator 4 is installed on the upper part of the reactor body 1 to collect the water, gas and mud mixture after the denitrification reaction and separate the nitrogen and floating mud therein. Figure 5 As shown in (a) and (b).

[0087] The primary separator 4 includes an outer cylinder 17 , an inner cylinder 18 and a cyclone water distributor 19 .

[0088] The upper part of the outer cylinder 17 is cylindrical, with an overflow water inlet at the top; the lower part is conical, with a water outlet 21 at the bottom; the cyclone water distributor 19 is installed in the outer cylinder 17, and is composed of a circle of umbrella-shaped plates, the angle between the plates and the umbrella-shaped cone generatrix is ​​45°, there is overlap between the plates, and there is a gap allowing liquid to pass through, and there is a vent at the top of the cyclone water distributor 19. The inner cylinder 18 is a cylindrical shape concentric with the outer cylinder 17, the top opening is 400mm lower than the outer cylinder, and the bottom opening is connected to the outer cylinder 17. A floating mud pipe is set at the upper part of the inner cylinder 18, with an angle of 45° downward, and the floating mud pipe passes through the outer cylinder and is connected to the floating mud port in the middle of the side wall of the reactor body 1.

[0089] In this embodiment, a total of 4 primary separators 4 are installed in 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. Surface load u = 0.013 m 3 / (m 2 .s).

[0090] The secondary separator 5 is installed at the bottom of the reactor body 1 and is used to precipitate and separate the denitrification sludge in the effluent of the primary separator 4. Figure 3 As shown in (a), (b) and (c).

[0091] In this embodiment, the external dimensions and internal structure of the secondary separator 5 are the same as those of embodiment 1. A total of four secondary separators 5 are installed in the reactor body 1, with external dimensions of 5700×2000×4200 mm, and are fixed to the bottom plate of the reactor body 1 by brackets. The surface load of the sedimentation zone of the secondary separator is 0.48 m 3 / (m 2 .h).

[0092] The circulation pump 6 is installed outside the reactor body 1, the pump suction port is connected to the circulation port 16 at the bottom of the secondary separator 5, and the pump outlet is connected to the reactor water inlet distribution system 2 to mix with the inlet water. The circulation flow returns to the reactor inlet water, ensuring sufficient contact between the wastewater and the denitrification sludge, and also provides the rising flow rate and stirring energy required to ensure the mixing effect of the reactor. In this embodiment, a total of 1 circulation pump is provided, with a rated flow rate of 220m 3 / h, and the corresponding reactor rising velocity is 4m / h.

[0093] The floating mud pump 7 is installed outside the reactor body 1, the pump suction port is connected to the floating mud pipe of the primary separator 4, and the pump outlet is connected to the reactor water inlet distribution system 2 to mix with the inlet water; a bypass is set at the pump outlet to discharge the remaining sludge to the sludge treatment system. In this embodiment, a floating mud pump is set with a rated flow of 10m 3 / h.

[0094] When in use, the influent of the reactor body 1 is lifted by the influent pump, and after merging with the circulating flow from the circulating pump 6 and the recovered sludge from the sludge pump 7, it is evenly distributed to the bottom cross section of the reactor through the influent distribution system 2 at the bottom of the reactor body 1, and then flows upward through the denitrifying sludge bed, and the nitrate in the wastewater is converted into nitrogen by the denitrifying bacteria. At the top of the reactor body 1, the mixed liquid after denitrification overflows into the primary separator 4 to separate the gas and floating sludge therein. The separated gas is collected at the top of the reactor body 1 and led out of the reactor through the breathing port 14. The floating sludge is connected to the floating sludge pump 7 through the 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 water inlet distribution system 2 through the floating sludge pump 7; the effluent of the primary separator 4 flows through the pipeline to the secondary separator 5 at the bottom of the reactor body 1, which is in the form of 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 area through the water distribution area, and flows upward through the inclined plate sedimentation area. The effluent after the sludge is separated flows out of the secondary separator and is discharged from the reactor body 1 through the first water 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 circulation flow, and returns to the water inlet distribution system 2.

[0095] Application Example 2

[0096] Example 2 was used to treat nitrate wastewater from an electronics industry. The reactor was designed to have an inlet flow rate of 360 m 3 / d,NO 3 - -N concentration is 870mg / L. Flocculent sludge is inoculated in the reactor. The treatment effect is shown in Table 2:

[0097] Table 2. Actual operation results of Example 2

[0098] Operation parameters unit Operational data Water treatment capacity <![CDATA[m 3 / d]]> 290～380 Reactor effective volume <![CDATA[m 3 ]]> 880 Inlet TN mg / L 812～960 Water TN mg / L 107～159 TN removal rate ％ 83～87 Volumetric load <![CDATA[kgN / (m 3 .d)]]> 0.29～0.39 Average sludge concentration g / L 4～6 Outlet SS mg / L 70～180 Floating mud phenomenon none

[0099] As described above, in the present invention, the wastewater is lifted by the water inlet pump, and after merging with the circulating flow from the circulating pump and the recovered floating sludge from the floating sludge pump, it is evenly distributed to the bottom of the reactor through the water inlet distribution system, and then flows upward through the denitrification sludge bed, and the nitrate in the wastewater is converted into nitrogen by the denitrifying bacteria. At the upper part of the reactor, the mixed solution after denitrification treatment overflows into the primary separator, effectively separating the gas and floating sludge therein, and the separated gas is led out of the reactor through the breathing port at the top of the reactor. After the floating sludge is discharged from the gas by the shearing action of the floating sludge pump, a part of it is discharged from the reactor as residual sludge, and the rest returns to the reactor to mix with the influent water; the effluent of the primary separator flows through the pipeline to the secondary separator at the bottom of the reactor, which is in the form of a fully enclosed inclined plate sedimentator, and the mud-water mixture flows through the water distribution area and the sedimentation area in turn, and the denitrification sludge is separated by gravity sedimentation, and the clear liquid effluent is discharged from the reactor through the outlet pipe; the separated sludge and the circulating flow are mixed with the reactor influent through the circulating pump to ensure the rising flow rate and stirring energy required for the mixing effect of the reactor.

[0100] The basic principles, main features and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A denitrification bioreactor, comprising a reactor body (1), a water inlet distribution system (2), a primary separator (4), a secondary separator (5), a circulation pump (6), and a floating mud pump (7), characterized in that: The reactor body (1) is provided with a first water inlet (8), a sludge outlet (9) and a circulation connection port (10) at the bottom of the side wall, a motor port (11) at the middle of the side wall, a first water outlet (12) at the upper part of the side wall, and a breathing port (14) at the top; The water inlet distribution system (2) is installed at the bottom of the reactor body (1) and adopts a perforated water distribution form with a hole diameter of 15 to 50 mm. After the reactor inlet water flow is merged with the circulating flow from the circulating pump (6) and the recovered floating mud from the floating mud pump (7), it is evenly distributed to the bottom of the reactor body (1); The primary separator (4) is located at the upper part of the reactor body (1), and is arranged outside the reactor or inside the reactor, and is used to collect the mixed liquid after the denitrification reaction and separate the nitrogen and floating mud therein; The primary separator (4) comprises an outer cylinder (17), an inner cylinder (18) and a cyclone water distributor (19); the upper portion of the outer cylinder (17) is cylindrical or prism-shaped, and is provided with a second water inlet; the lower portion of the outer cylinder (17) is conical or pyramid-shaped, and is provided with a second water outlet (21) at the bottom, and the outlet water flows to the secondary separator (5) by gravity; the side wall of the primary separator (4) is also provided with a water inlet trough (20) and a sludge pipe (22) inclined downward; The outer cylinder (17) is also provided with a cyclone water distributor (19) on the upper part. The cyclone water distributor (19) is composed of a circle of umbrella-shaped plates. The angle between the plates and the umbrella-shaped cone generatrix is ​​10 to 60 degrees. The plates overlap and have gaps to allow liquid to pass through. The cyclone water distributor (19) causes the water flow to be splashed and dispersed into droplets. The inner tube (18) is concentric with the outer tube (17), with both ends open, the bottom end communicates with the outer tube (17), and the top end is 200 to 800 mm lower than the outer tube (17); a floating mud pipe is arranged on the upper part of the inner tube (18), with an angle of 30 to 60 degrees downward, and the floating mud pipe is connected to the floating mud pump (7); and a vent hole is arranged on the top of the primary separator (4); The secondary separator (5) is installed at the bottom of the reactor body (1).

2. A denitrification bioreactor according to claim 1, characterized in that: The reactor body (1) is cylindrical or rectangular in shape, made of metal structure or reinforced concrete structure, with one of the diameter or side length being 3 to 20 m, and the height being 8 to 24 m.

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 water trough (3) is installed on the upper part of the reactor body (1) to collect overflow water from the top of the reactor body (1). An adjustable weir plate is used. The end of the overflow water 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 0.5 m 3 / (m 2 .s).

5. A denitrification bioreactor according to claim 1 or 3, characterized in that: The secondary separator (5) is a fully enclosed type, comprising a sedimentation module (25) and a sludge hopper (26); The top of the sedimentation module (25) is provided with a top plate (30), and a third water inlet (34) is arranged on the top plate (30) and is connected to the second water outlet (21) of the primary separator (4); In the sedimentation module (25), a longitudinal partition (32) divides the sedimentation module (25) into a water distribution area (27) and a sedimentation area (28). The sedimentation area (28) is provided with an inclined plate (29). The inclined plate (29) has a length of 0.6 to 2 m, an inclination angle of 50 to 60°, a spacing of 50 to 150 mm, and a surface load of 0.2 to 0.75 m 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) through the outlet pipe on the side wall of the reactor body (1); The precipitation module 25 has a top plate (30) on the top, and a second water inlet (34) is arranged on the top plate 30, which is connected to the second water outlet (21) of the primary separator (4); two side plates (31) are arranged on the side, and an end plate 1 (32) and an end plate 2 (33) are arranged at each end, wherein a third water outlet (35) is arranged on the end plate 1 (32), which is connected to the first water outlet (12) on the upper part of the 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), and 1 to 3 sludge hoppers (26) are arranged along the length direction. The inclination angle of the sludge hopper (26) is 50 to 60 degrees. Each sludge hopper (26) is provided with a circulation port (16), which is controlled by an independent valve and connected to a circulation pump (6).

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

8. A denitrification bioreactor according to claim 1, characterized in that: The circulation pump (6) is installed outside the reactor body (1), the pump suction port is connected to the circulation port (10) 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 floating mud pump (7) is installed outside the reactor body (1), and the pump suction port is connected to the floating mud pipe (22) of the primary separator (4). The pump outlet has two destinations: one is a mud discharge pipe, which discharges the floating mud to the sludge treatment system; the other is a floating mud recovery pipe, which is connected to the water inlet distribution system (2) of the reactor body (1) and mixed with the inlet water.

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