Efficient denitrification reactor

Abstract

The invention discloses an efficient denitrification reactor which comprises a main reactor, a front-end sludge interception tank arranged at the front end of the main reactor and a rear-end sludge interception tank arranged at the rear end of the main reactor, and the front-end sludge interception tank is used for carrying out sludge interception and dissolved oxygen consumption on sewage before the sewage enters the main reactor; the rear-end sludge interception tank is used for carrying out sludge interception on sewage discharged from the main reactor, and the main reactor is used for culturing denitrification exclusive sludge and is provided with a micro-aerobic supply device. The high-efficiency denitrification reactor can be applied to sewage treatment processes with front nitrification and rear denitrification, so that an anoxic working condition does not depend on high-power backflow of nitrification liquid any more, the anoxic working condition is effectively prevented from being interfered by other reactions, and the high-efficiency denitrification reactor has the advantages of high reaction efficiency, low working condition control difficulty and the like.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a high-efficiency denitrification reactor. Background Technology

[0002] Municipal wastewater is often treated using the A / O process. In the traditional A / O process (anaerobic-anoxic-aerobic), sludge circulates throughout the system through nitrification liquor recirculation and sludge recirculation. Therefore, the sludge from each reaction unit is mixed, rather than strictly separated. This means that the sludge from the anaerobic, anoxic, and aerobic units is mixed together, but the different environmental conditions in each reaction unit lead to different growth advantages for different bacterial communities. For example, nitrifying bacteria in the aerobic tank are active under aerobic conditions, while denitrifying bacteria in the anoxic tank are active under anoxic conditions, but sludge recirculation causes the bacterial communities to mix.

[0003] Therefore, in traditional A / O processes, each reaction unit uses mixed sludge instead of dedicated sludge. For example, in the anoxic tank, denitrifying bacteria account for 5-10% of the total sludge, while in the aerobic tank, nitrifying bacteria account for only about 10-30% of the total sludge. This results in a low reaction rate for each reaction unit, making it susceptible to interference from other reactions. It also makes it difficult to control sludge age and concentration, and the operating conditions are very challenging.

[0004] In the treatment of organic wastewater, conventional nitrification and denitrification processes mostly employ an A / O process with denitrification pre-treatment. However, in wastewater with high NH3-N (TN) concentrations, high-level recirculation of the nitrified liquor is necessary to ensure efficient removal during pre-nitrification. This high recirculation inevitably compromises the effective maintenance of anoxic conditions. Therefore, designing a highly efficient denitrification reactor that can be used as a post-treatment without relying on high-level recirculation of the nitrified liquor has become a pressing technical challenge in this field. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a high-efficiency denitrification reactor that can be applied in wastewater treatment processes with pre-nitrification and post-nitrification. This eliminates the need for high-level reflux of nitrification liquid under anoxic conditions, effectively ensuring that the anoxic conditions are not affected by other reactions. It has the advantages of high reaction efficiency and low difficulty in controlling the operating conditions.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A high-efficiency denitrification reactor includes a main reactor, a front-end sludge interception tank located at the front end of the main reactor, and a rear-end sludge interception tank located at the rear end of the main reactor. The front-end sludge interception tank is used to intercept sludge and consume dissolved oxygen in the wastewater before it enters the main reactor. The rear-end sludge interception tank is used to intercept sludge in the wastewater exiting the main reactor. The main reactor cultivates denitrification-specific sludge and is equipped with a micro-oxygen supply device.

[0008] Furthermore, the front-end sludge interception tank adopts an inclined tube sedimentation tank or a vertical flow sedimentation tank, and the rear-end sludge interception tank adopts an inclined tube sedimentation tank or a vertical flow sedimentation tank.

[0009] Furthermore, the front-end sludge interception tank is connected to a front-end sludge discharge facility for discharging the sludge intercepted in the tank, and the rear-end sludge interception tank is connected to a rear-end sludge discharge facility for discharging the sludge intercepted in the tank.

[0010] Furthermore, the rear-end sludge discharge facility is connected to a sludge return facility, which is used to return the sludge discharged from the rear-end sludge discharge facility to the main reactor.

[0011] Furthermore, the main reactor is a tubular reactor, which employs multiple sets of pipes, each set of pipes being vertically arranged, with a height of 2.5m to 4.5m and a diameter of Ø300 to Ø1200.

[0012] Furthermore, the multiple sets of pipes are arranged side by side and connected end to end.

[0013] Furthermore, the tubular reactor is equipped with a wastewater circulation device, one end of which is connected to the outlet at the rear end of the tubular reactor, and the other end of which is connected to the inlet at the front end of the tubular reactor.

[0014] Furthermore, the main reactor is a tower reactor, which has multiple layers of trays inside, each tray having a packing layer. The micro-oxygen supply device is located at the bottom of the tower reactor, and a water distribution system is also provided at the bottom of the tower reactor, which is connected to the water inlet of the tower reactor.

[0015] Furthermore, the tower reactor is equipped with a wastewater circulation device, which is connected to the water distribution system.

[0016] Furthermore, the high-efficiency denitrification reactor also includes an online monitoring system and an automatic control system. The online monitoring system includes a temperature sensor, pH meter, sludge concentration meter, flow meter, and COD meter. CrSensors, including dissolved oxygen, nitrate nitrogen, and total nitrogen sensors, are used in an automatic control system to monitor temperature, pH, sludge concentration, flow rate, and COD. Cr Automatic regulation of dissolved oxygen, nitrate nitrogen, and total nitrogen.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] Unlike traditional A / O processes that pre-denitrification, the high-efficiency denitrification reactor of this invention can be applied to wastewater treatment processes with pre-nitrification and post-denitrification, achieving unidirectional flow of wastewater between nitrification and denitrification, thus eliminating the need for high-level reflux of nitrification liquid under anoxic conditions. To achieve unidirectional flow of wastewater between nitrification and denitrification, the denitrification reactor must have a high level of reaction efficiency and anti-interference capability to achieve a high level of NH3-N(TN) removal.

[0019] Therefore, in the high-efficiency denitrification reactor of this invention, a front-end sludge interception tank is set at the front end of the main reactor. The wastewater from the pre-nitrification unit (i.e., the aerobic zone) will first enter the front-end sludge interception tank. The effluent from the aerobic zone carries sludge and high concentrations of dissolved oxygen. Therefore, before the wastewater enters the main reactor, the front-end sludge interception tank is needed to intercept sludge and consume dissolved oxygen. On this basis, in order to avoid the main reactor becoming anaerobic due to excessively low dissolved oxygen concentration, the main reactor needs to be equipped with a micro-oxygen supply device. The micro-oxygen supply device is used to supply a low level of oxygen to the water in the main reactor to avoid excessively high dissolved oxygen concentration due to excessive aeration, so that the dissolved oxygen concentration in the main reactor is suitable for anoxic conditions (usually dissolved oxygen DO: 0.2~0.6 mg / L). In addition, the sludge interception tank at the rear end of the main reactor can intercept the sludge from the effluent of the main reactor. This ensures that the sludge from the effluent of the main reactor will not affect the next stage of treatment. The intercepted sludge can be returned to the main reactor for continued use. The setting of the front and rear sludge interception tanks can facilitate the management of sludge concentration and sludge age, as well as improve the anti-interference ability.

[0020] Because sludge does not circulate between reaction units at each level, each reaction unit can use dedicated sludge. This is a key factor in improving reaction efficiency and resistance to interference. In the traditional A / O process, denitrifying bacteria account for 5-10% of the total sludge in the anoxic tank. The low proportion of denitrifying bacteria is caused by the return of nitrifying liquor and the mixed return of sludge. However, in the main reactor of this invention, denitrification-specific sludge is cultivated (i.e., the proportion of denitrifying bacteria in the sludge is extremely high or only denitrifying bacteria, theoretically reaching 90%~100%). The cultivation and use of denitrification-specific sludge significantly increases reaction efficiency (up to 10 times or more) and also greatly reduces interference from other reactions. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the high-efficiency denitrification reactor according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of a tower reactor in an embodiment of the present invention.

[0023] In the picture:

[0024] 100. Front-end sludge interception tank; 101. Front-end sludge discharge facility; 200. Main reactor; 201. Micro-oxygen supply device; 202. Wastewater circulation device; 203. Packing layer; 204. Water distribution system; 300. Back-end sludge interception tank; 301. Back-end sludge discharge facility; 302. Sludge return facility. Detailed Implementation

[0025] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0026] This invention provides a high-efficiency denitrification reactor. The high-efficiency denitrification reactor includes a main reactor 200, a front-end sludge retention tank 100 located at the front end of the main reactor 200, and a rear-end sludge retention tank 300 located at the rear end of the main reactor 200. The front-end sludge retention tank 100 is used to retain sludge and consume dissolved oxygen in the wastewater (here referring to the effluent from the aerobic zone / nitrification unit) before it enters the main reactor 200. The rear-end sludge retention tank 300 is used to retain sludge from the wastewater effluent from the main reactor 200. The main reactor 200 cultivates denitrification-specific sludge and is equipped with a micro-aerobic supply device 201. The effluent from the front-end sludge retention tank 100 can enter the main reactor 200 through natural flow or a pump, and the effluent from the main reactor 200 can enter the rear-end sludge retention tank 300 through natural flow or a pump.

[0027] In the high-efficiency denitrification reactor of this invention embodiment, the front-end sludge interception tank 100 can be an inclined tube sedimentation tank or a vertical flow sedimentation tank, and the rear-end sludge interception tank 300 also adopts an inclined tube sedimentation tank or a vertical flow sedimentation tank. The front-end sludge interception tank 100 adopts a sedimentation tank, specifically to achieve solid-liquid separation through gravity sedimentation to intercept suspended sludge. The microorganisms in the sludge layer at the bottom of the sedimentation tank will consume a large amount of dissolved oxygen through endogenous respiration.

[0028] In the high-efficiency denitrification reactor of this embodiment, the front-end sludge interception tank 100 is connected to a front-end sludge discharge facility 101 for discharging the sludge intercepted in the tank, and the rear-end sludge interception tank 300 is connected to a rear-end sludge discharge facility 301 for discharging the sludge intercepted in the tank. The front-end sludge discharge facility 101 and the rear-end sludge discharge facility 301 can be connected to a wastewater treatment system.

[0029] In the high-efficiency denitrification reactor of this embodiment of the invention, the downstream sludge discharge facility 301 may be connected to a sludge return facility 302, which is used to return the sludge discharged by the downstream sludge discharge facility 301 to the main reactor 200; specifically, the sludge return ratio may be 1-3 times.

[0030] Regarding the structure of the main reactor 200, it can be either a tubular reactor or a tower reactor. A tubular denitrification reactor is suitable for treating water volumes less than 200 m³. 3 A wastewater treatment system with a capacity of / d, featuring a tower-type denitrification reactor suitable for treating water volumes greater than 200m³. 3 / d of wastewater treatment system.

[0031] Specifically, when the main reactor 200 is a tubular reactor, the design flow rate of the tubular reactor is v>3m / h to prevent sludge settling and pipe scaling. For specific structural details, please refer to [reference needed]. Figure 1 The tubular reactor employs multiple sets of pipes, each set arranged vertically, with a height of 2.5m to 4.5m and a diameter of Ø300 to Ø1200. These multiple sets of pipes are arranged side-by-side and connected end-to-end. Furthermore, the tubular reactor is equipped with a wastewater circulation device 202. One end of the wastewater circulation device 202 is connected to the outlet at the rear end of the tubular reactor, and the other end is connected to the inlet at the front end of the tubular reactor. The internal circulation ratio here can be 3-5 times.

[0032] When the main reactor 200 is a tower reactor, the specific structure can be found in [reference needed]. Figure 2 The tower reactor has multiple trays inside, each tray containing a packing layer 203 with a specific gravity of 0.8-1.0 and a height of 500-800 mm. A micro-oxygen supply device 201 is located at the bottom of the tower reactor, and a water distribution system 204 is also installed at the bottom of the tower reactor, which is connected to the inlet of the tower reactor. In addition, the tower reactor is equipped with a wastewater circulation device (in... Figure 2 (omitted), and the wastewater circulation device is connected to the water distribution system 204, with an internal circulation ratio of 3-5 times. Specifically, the design flow velocity v of the inlet and outlet of the tower reactor is >0.7 m / h, and the flow velocity v inside the tower is >3 m / h.

[0033] The high-efficiency denitrification reactor of this invention also includes an online monitoring system and an automatic control system. The online monitoring system includes a temperature sensor, a pH meter, a sludge concentration meter, a flow meter, and a COD meter. Cr Sensors, including dissolved oxygen, nitrate nitrogen, and total nitrogen sensors, are used in an automatic control system to monitor temperature, pH, sludge concentration, flow rate, and COD. Cr Automatic adjustment of dissolved oxygen, nitrate nitrogen, and total nitrogen. Taking the main reactor 200 as a tubular reactor as an example, refer to... Figure 1 The front-end sludge interception tank 100 should be equipped with a total nitrogen sensor ( Figure 1 TN and COD Cr sensor( Figure 1 The COD (chemical oxygen demand) in the sludge retention tank 300 at the back end is also equipped with a total nitrogen sensor and a COD sensor. Cr A flow meter should be installed at the inlet of the main reactor 200. Figure 1 In addition to the Q mentioned above, the main reactor 200 also needs to be equipped with a dissolved oxygen sensor (DO), a temperature sensor (T), a pH meter, a sludge concentration meter (MLSS), and a nitrate nitrogen sensor. This embodiment of the invention ensures fully automatic and stable operation of the denitrification reactor through an online monitoring system and an automatic adjustment system.

[0034] The main reactor 200 of this embodiment of the invention has the following operating parameters:

[0035] Design reaction temperature: 15~35℃. Dissolved oxygen (DO): 0.2~0.6 mg / L. pH: 6.5~8.0. Sludge concentration: 5000 mg / L~20000 mg / L. Sludge loading: 0.3~0.8 kg NO3 - -N / (kg MLSS·d). Sludge age: 12d~18d. The amount of carbon source added should ensure a reactor C / TKN ratio of 4~7. Hydraulic retention time: 6~8h. Denitrification efficiency: 85%~95%.

[0036] The high-efficiency denitrification reactor of this invention is more suitable for operation in wastewater with high NH3-N(TN), such as wastewater with total nitrogen TN > 300 mg / L.

[0037] The advantages of the embodiments of the present invention compared with the prior art are as follows:

[0038] Unlike traditional A / O processes that pre-denitrification, the high-efficiency denitrification reactor of this invention can be applied to wastewater treatment processes with pre-nitrification and post-denitrification, achieving unidirectional flow of wastewater between nitrification and denitrification, thus eliminating the need for high-level reflux of nitrification liquid under anoxic conditions. To achieve unidirectional flow of wastewater between nitrification and denitrification, the denitrification reactor must have a high level of reaction efficiency and anti-interference capability to achieve a high level of NH3-N(TN) removal.

[0039] Therefore, in the high-efficiency denitrification reactor of the present invention, a front-end sludge interception tank 100 is provided at the front end of the main reactor 200. The wastewater from the pre-nitrification unit (i.e., the aerobic zone) will first enter the front-end sludge interception tank 100. The effluent from the aerobic zone carries sludge and high concentrations of dissolved oxygen. Therefore, before the wastewater enters the main reactor 200, the front-end sludge interception tank 100 needs to intercept sludge and consume dissolved oxygen. On this basis, in order to avoid the main reactor 200 becoming anaerobic due to excessively low dissolved oxygen concentration, the main reactor 200 needs to be equipped with a micro-oxygen supply device 201. The micro-oxygen supply device 201 is used to supply a low level of oxygen to the water in the main reactor 200, so as to avoid both anaerobic conditions and excessively high dissolved oxygen concentration due to excessive aeration, so that the dissolved oxygen concentration in the main reactor 200 is suitable for anoxic conditions (usually dissolved oxygen DO: 0.2~0.6 mg / L). In addition, the sludge interception tank 300 at the rear end of the main reactor 200 can intercept the sludge from the effluent of the main reactor 200. This ensures that the sludge from the effluent of the main reactor 200 will not affect the next stage of treatment. The intercepted sludge can be returned to the main reactor 200 for continued use. The setup of the front sludge interception tank 100 and the rear sludge interception tank 300 can facilitate the management of sludge concentration and sludge age, as well as improve the anti-interference ability.

[0040] Because sludge does not circulate between reaction units at each level, each reaction unit can use dedicated sludge. This is a key factor in improving reaction efficiency and resistance to interference. In traditional A / O processes, denitrifying bacteria account for 5-10% of the total sludge in the anoxic tank. The low proportion of denitrifying bacteria is caused by the return of nitrifying liquid and the mixed return of sludge. However, in the main reactor 200 of this invention, dedicated denitrification sludge is cultivated, meaning that the proportion of denitrifying bacteria in the sludge is extremely high or only denitrifying bacteria. Theoretically, the proportion of denitrifying bacteria can reach 90% to 100%. The cultivation and use of dedicated denitrification sludge significantly increases reaction efficiency (up to 10 times or more) and also greatly reduces interference from other reactions. Using dedicated sludge can significantly increase sludge concentration without worrying about sludge bulking, effectively reducing the risk of sludge bulking.

[0041] In summary, the high-efficiency denitrification reactor of the present invention can be applied in wastewater treatment processes with pre-nitrification and post-nitrification, so that the anoxic conditions no longer rely on high-multiplier reflux of nitrification liquid, effectively ensuring that the anoxic conditions are not disturbed by other reactions, and has the advantages of high reaction efficiency and low difficulty in operating conditions control.

[0042] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A high-efficiency denitrification reactor, characterized in that, It includes a main reactor, a front sludge interception tank located at the front end of the main reactor, and a rear sludge interception tank located at the rear end of the main reactor. The front sludge interception tank is used to intercept sludge and consume dissolved oxygen in the wastewater before it enters the main reactor. The rear sludge interception tank is used to intercept sludge in the wastewater coming out of the main reactor. The main reactor cultivates denitrification-specific sludge and is equipped with a micro-oxygen supply device.

2. The high-efficiency denitrification reactor as described in claim 1, characterized in that, The front-end sludge interception tank adopts an inclined tube sedimentation tank or a vertical flow sedimentation tank, and the rear-end sludge interception tank adopts an inclined tube sedimentation tank or a vertical flow sedimentation tank.

3. The high-efficiency denitrification reactor as described in claim 1, characterized in that, The front-end sludge interception tank is connected to a front-end sludge discharge facility for discharging the sludge intercepted in the tank, and the rear-end sludge interception tank is connected to a rear-end sludge discharge facility for discharging the sludge intercepted in the tank.

4. The high-efficiency denitrification reactor as described in claim 3, characterized in that, The rear-end sludge discharge facility is connected to a sludge return facility, which is used to return the sludge discharged from the rear-end sludge discharge facility to the main reactor.

5. The high-efficiency denitrification reactor as described in claim 1, characterized in that, The main reactor is a tubular reactor, which uses multiple sets of pipes. Each set of pipes is vertically arranged, with a height of 2.5m to 4.5m and a diameter of Ø300 to Ø1200.

6. The high-efficiency denitrification reactor as described in claim 5, characterized in that, The multiple sets of pipes are arranged side by side and connected end to end.

7. The high-efficiency denitrification reactor as described in claim 6, characterized in that, The tubular reactor is equipped with a wastewater circulation device. One end of the wastewater circulation device is connected to the outlet at the rear end of the tubular reactor, and the other end of the wastewater circulation device is connected to the inlet at the front end of the tubular reactor.

8. The high-efficiency denitrification reactor as described in claim 1, characterized in that, The main reactor is a tower reactor, which has multiple trays inside. Each tray has a packing layer. The micro-oxygen supply device is located at the bottom of the tower reactor, and a water distribution system is also provided at the bottom of the tower reactor. The water distribution system is connected to the water inlet of the tower reactor.

9. The high-efficiency denitrification reactor as described in claim 8, characterized in that, The tower reactor is equipped with a wastewater circulation device, which is connected to the water distribution system.

10. The high-efficiency denitrification reactor as described in claim 1, characterized in that, The high-efficiency denitrification reactor also includes an online monitoring system and an automatic control system. The online monitoring system includes a temperature sensor, pH meter, sludge concentration meter, flow meter, and COD meter. Cr Sensors, including dissolved oxygen, nitrate nitrogen, and total nitrogen sensors, are used in an automatic control system to monitor temperature, pH, sludge concentration, flow rate, and COD. Cr Automatic regulation of dissolved oxygen, nitrate nitrogen, and total nitrogen.

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