Granular sludge biological selector based on short-cut nitrification and anammox and wastewater treatment method and application thereof

Abstract

The present application provides a kind of short-range nitrification anaerobic ammonia oxidation based granular sludge biological selector and wastewater treatment method and application.The selector includes: water collecting pool, water inlet pipe and sludge return pipe, the inlet end of the water inlet pipe is used to access wastewater, the outlet end is inserted into the bottom of the water collecting pool;The bottom of the water collecting pool is provided with aeration disc, and the upper portion of the aeration disc is provided with a sedimentation tank;Gas pipe is passed into the sedimentation tank from the upper portion, and the middle portion of the sedimentation tank is provided with a water collecting tank, and the bottom of the water collecting tank is connected with a water outlet pipe leading to the outside of the water collecting pool;The inlet end of the sludge return pipe is inserted into the bottom of the sedimentation tank, and the outlet end is inserted into the bottom of the water collecting pool;Wherein, the number of the sludge return pipe is multiple, and the outlet end of multiple sludge return pipes is arranged in the form of vortex, to increase the shear force of water flow to facilitate granulation, so that sewage and sludge are uniformly mixed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, and particularly relates to a granular sludge biological selector based on short-cut nitrification and anaerobic ammonia oxidation, a wastewater treatment method and application. BACKGROUND

[0002] Partial nitrification / anaerobic ammonia oxidation (PN / A) process is a resource-saving alternative for removing nitrogen from municipal wastewater. Compared with traditional biological denitrification process, PN / A process avoids the use of organic carbon source for denitrification, reduces sludge by about 85%, and saves about 60% of oxygen supply, thereby reducing energy demand. It can make the wastewater treatment plant closer to energy balance, so PN / A technology is first applied to high-concentration ammonia-nitrogen wastewater with insufficient carbon source.

[0003] The process is effective mainly because the dense structure of granules has excellent biomass retention capacity and superior denitrification performance. Although the importance of PN / A is increasing worldwide, its utilization is still difficult, and the enrichment of anaerobic ammonia-oxidizing bacteria (AnAOB) is still one of the main bottlenecks. In the operation of sewage treatment plants, the performance of granule-based PN / A is highly affected by AnAOB and its co-community, and the stable aggregation of granular biomass is particularly important for effective removal of nutrients in mainstream wastewater treatment. The low growth rate of AnAOB and its obvious sensitivity to various environments have used many strategies to enrich slow-growing AnAOB and promote biomass culture, among which sludge granulation is a feasible and economical method.

[0004] The initial stage of sludge granulation is determined by different forces and properties of biomass, including high fluid dynamic shear force, diffusion, cell surface properties, and reactor height-diameter ratio and settling time of selecting dense microbial aggregates. The enrichment of AnAOB during the granulation process is attributed to the unique physical properties of granular sludge. Specifically, granular sludge has higher biomass density and settling velocity than floccules, thereby providing longer biomass retention time to avoid AnAOB being washed out. It is currently found that AnAOB cells cultured in an upflow column reactor will self-aggregate. Anaerobic ammonia oxidation granulation can be obtained by high specific surface area, however, in actual engineering applications, a large reactor volume is required for high specific surface area, which will make the sewage treatment plant expand capacity and space utilization is not high. SUMMARY

[0005] To solve the above technical problems, the present application provides a granular sludge biological selector based on short-cut nitrification and anaerobic ammonia oxidation and a wastewater treatment method and application.

[0006] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0007] The present application provides a kind of short-range nitrification anaerobic ammonia oxidation based granular sludge biological selector, the selector includes: water collecting pool, water inlet pipe and sludge return pipe, the inlet end of the water inlet pipe is used to access wastewater, the outlet end is inserted into the bottom of the water collecting pool;The bottom of the water collecting pool is provided with aeration disc, and the aeration disc is provided with a sediment tank above;The sediment tank is connected with air pipe from top, and the middle part of the sediment tank is provided with a water collecting tank, and the bottom of the water collecting tank is connected with water outlet pipe leading to the outside of the water collecting pool;The inlet end of the sludge return pipe is inserted into the bottom of the sediment tank, and the outlet end is inserted into the bottom of the water collecting pool;Wherein, the number of the sludge return pipe is multiple, and the outlet end of multiple sludge return pipe is arranged in vortex form, to increase the shear force of water flow to facilitate granulation, so that sewage and sludge are uniformly mixed.

[0008] Further, DO probe and pH probe controlled by WTW host are arranged in the water collecting pool and outside the sediment tank.

[0009] Further, the water inlet pipe is also connected with pH regulator storage tank.

[0010] Further, liquid flow meter is arranged between the pH regulator storage tank and the water inlet pipe.

[0011] Further, the outlet of the pH regulator storage tank is also provided with a dosing pump, and the dosing pump is controlled by the control system.

[0012] Further, the bottom of the water collecting pool is connected with the air outlet of the air blower, and air flow meter is arranged between the air blower and the water collecting pool;The air blower is controlled by the control system.

[0013] Further, the air pipe is also connected with air blower, and air flow meter is arranged between the air blower and the air pipe;The air blower is controlled by the control system.

[0014] The present application also provides a wastewater treatment method, which is applied to the short-range nitrification anaerobic ammonia oxidation based granular sludge biological selector as described above, and the method comprises the following steps: wastewater enters the water collecting pool through the water inlet pipe, the aeration disc is aerated to remove most of the COD, and ammonia nitrogen (NH4 + -N) is converted into nitrite (NO2 - -N);The wastewater in the water collecting pool enters the sediment tank in the form of upflow as the water flows in;The granular sludge in the wastewater is separated to the bottom through the sediment tank, and the treated wastewater enters the water outlet pipe from the water collecting tank and is discharged;The sludge at the bottom of the sediment tank enters the sludge return pipe through the airflow difference generated by the air pipe and returns to the bottom of the water collecting pool.

[0015] Further, the method further comprises: the DO probe 15 and the pH probe 16 perform real-time monitoring on the sewage in the water collecting pool, the DO of the sewage is controlled to be less than 0.5, and the pH value is controlled to be between 6 and 9; when the sewage quality does not meet the requirement, the control system starts the pH regulator storage tank, and the dosing pump is controlled to add the medicine into the sewage through the liquid flow meter; and / or air is blown into the sewage through the air flow meter and the air blower.

[0016] The application also provides application of the granular sludge biological selector based on short-cut nitrification and anaerobic ammonia oxidation in the field of high-ammonia-nitrogen wastewater treatment.

[0017] Compared with the prior art, the technical scheme provided by the application has at least the following advantages:

[0018] The short-cut nitrification and anaerobic ammonia oxidation (PN / A) method is used for granulation, and compared with the traditional wastewater treatment technology, the aeration energy consumption is only 55-60% of that of the traditional process, which is very favorable for reducing operation cost and reducing energy consumption, the anaerobic ammonia oxidation process does not need to add additional carbon source, thereby reducing the dependence on organic matter and the emission of greenhouse gases, the coupling process also reduces the complexity and energy consumption of the traditional biological denitrification process to a certain extent, and the stability of the system and the nitrogen removal efficiency are improved by optimizing the reaction conditions.

[0019] Compared with the traditional reactor with a large height-diameter ratio, the reactor used in the application has a relatively high packing density, the microorganisms and the substrate are in more sufficient contact, the load of the reactor is improved, the hydrodynamic conditions are more stable, and good mixing performance is easily achieved. Moreover, the reactor has a small footprint, flexible operation, low investment and operation cost, although the reactor with a large height-diameter ratio has certain application advantages in some cases, the reactor used in the application has certain advantages in mixing performance, operation flexibility, start-up and recovery time, monitoring and management, investment and operation cost and adaptability.

[0020] The gas stripping process is used for granulation. The application of the gas stripping process in granulation has the advantages of improving efficiency, reducing energy consumption, reducing wear, improving uniformity, strong adaptability, safety, environmental protection and flexible control. The high fluidity of the gas can quickly and effectively transfer the granular materials from one place to another, improving the lifting efficiency of the materials. Compared with the traditional mechanical lifting mode, the gas stripping process usually has lower energy consumption because the energy required for gas flow is lower than that required for mechanical movement.

[0021] The vortex is used for granulation at the bottom of the biological selection pool. The vortex increases the shear force of the water flow, and the advantages of the vortex for granulation mainly include improving the uniformity and production efficiency of the particles, promoting the mixing and reaction speed of the materials, and improving the shape of the particles. BRIEF DESCRIPTION OF DRAWINGS

[0022] One or more embodiments are illustrated by way of example in the figures that form a part of this disclosure and which are shown by way of illustration in which, unless otherwise specified, the figures are not necessarily drawn to scale.

[0023] Figure 1 is an anaerobic ammonia oxidation biological selector diagram;

[0024] Figure 2 is a sedimentation tank detail drawing;

[0025] Figure 3 is an anaerobic ammonia oxidation biological selector control diagram.

[0026] In the figure, the water inlet pipe 1, the sludge return pipe 2, the gas pipe 3, the water collecting tank 4, the water outlet pipe 5, the sedimentation tank 6, the aeration disc 7, the control system 8, the dosing pump 9, the pH regulator storage tank 10, the liquid flow meter 11, the air flow meter 12, the air blower 13, the WTW main machine 14, the DO probe 15, and the pH probe 16. DETAILED DESCRIPTION

[0027] At present, the reactor granular sludge granulation technology mainly includes aerobic granular sludge technology, anaerobic granular sludge technology, fluidized bed sludge granulation technology, biofilm granular sludge technology, multiphase flow granular sludge technology, and mixed sludge granulation technology. The use of PN / A for granulation of high COD and ammonia-nitrogen wastewater reduces the aeration in the nitrification stage, and does not need to add an organic carbon source. The operation energy consumption of the PN / A process is low. The space is saved, and the reactor volume can be reduced. The PN / A process can achieve high ammonia-nitrogen removal efficiency, especially under high COD conditions, the performance of the Anammox reaction is improved through the pre-nitrification stage. Compared with the reactor with a large height-diameter ratio, such as the EGSB reactor used to cultivate anaerobic granular sludge in “A method for improving the efficiency of anaerobic sludge granulation” (CN107352647A), the actual organic wastewater ammonia-nitrogen is only 368±54 mg / L, and an exogenous signal molecule needs to be added. The “Urban sewage low-carbon denitrification and phosphorus removal device and method based on partial return sludge deep anaerobic treatment” (CN113998783A) is not convenient for actual engineering operation and has insufficient ammonia-nitrogen removal capacity.

[0028] Therefore, the present application adopts a tank body nesting device to suck the sludge at the bottom of the sedimentation tank into the return sludge pipe through the gas return device, and the sludge is discharged in the form of vortex from the pipe, thereby strengthening the granulation effect of the sludge, improving the ammonia-nitrogen removal rate, and reducing the floor area of the tank.

[0029] In order to facilitate the understanding of the embodiments of the present application, further explanation and description will be made below, and each embodiment does not constitute a limitation on the embodiments of the present application.

[0030] Embodiment 1: The present application provides a short-cut nitrification-based granular sludge biological selector for anaerobic ammonia oxidation, as shown in Figure 1 and Figure 2 The selector comprises a water collecting pool, a water inlet pipe 1 and a sludge return pipe 2, the inlet end of the water inlet pipe 1 is used for accessing wastewater, and the outlet end extends into the bottom of the water collecting pool; the bottom of the water collecting pool is provided with an aeration disc 7, and the aeration disc 7 is provided above a sedimentation tank 6; the sedimentation tank 6 is provided with a water collecting tank 4 in the middle, and the bottom of the water collecting tank 4 is connected with a water outlet pipe 5 leading out of the water collecting pool; the inlet end of the sludge return pipe 2 extends into the bottom of the sedimentation tank 6, and the outlet end extends into the bottom of the water collecting pool; wherein the number of the sludge return pipe 2 is multiple, and the outlet ends of the multiple sludge return pipes 2 are arranged in the form of vortex to increase the shear force of water flow and facilitate granulation, so that the wastewater and the sludge are uniformly mixed.

[0031] The short-cut nitrification-based granular sludge biological selector for anaerobic ammonia oxidation, the working process is as shown in Figure 3 , and specifically as follows:

[0032] The wastewater from the last unit enters the water collecting pool through the water inlet pipe 1, and most of the COD is removed through the aeration disc 7, so as to promote the microorganisms to convert NH4 + -N into NO2 - -N, and part of the organic matter is decomposed into carbon dioxide and energy. This process can improve the biodegradability of the wastewater and provide the required nitrite for the anaerobic ammonia oxidation (Anammox) reaction. The present application is provided with a control system 8, which is monitored in real time by a DO probe 15 and a pH probe 16, so that DO < 0.5 and the pH value is usually controlled between 6-9 to promote the accumulation of NO2 - -N. When the water quality does not meet the requirements, the control system 8 starts the pH regulator storage tank 10, and the dosing pump 9 is controlled by the liquid flow meter 11 to add the medicine. If the DO does not meet the requirements, the air flow meter 12 is read by the control system to start the air blower 13, and the size of the air flow of the air blower 13 is adjusted to control the DO.

[0033] Wherein, the DO probe 15 and the pH probe 16 are also connected with the WTW host 14, and the WTW host 14 is used for displaying the DO value and the pH value.

[0034] The anaerobic ammonia oxidation microorganisms directly convert NH4 + -N and NO2 -- N is converted to nitrogen gas (N2). This process does not require oxygen, so it is carried out under anaerobic conditions, greatly reducing the amount of aeration required. The optimal pH value for the Anammox reaction is between 7.5-8.0, and the temperature is between 30-38℃. The aeration amount of the process is shown in Table 1-1. The wastewater enters the sedimentation tank 6, and the sludge and water are separated in the sedimentation tank. The air pipe 3 blows air into the sludge, which is returned to the sump through the sludge return pipe 2, and the air blown by the air pipe 3 can also further remove NH4 + - N in the wastewater.

[0035] Table 1-1 Anammox air requirement

[0036]

[0037] Example 2: The present application provides a granular sludge biological selector based on short-cut nitrification and anammox, wastewater enters the sump through the influent pipe 1, part of the sludge deposits at the bottom of the sump, and the light sludge and wastewater are separated in the sedimentation tank. The sludge is returned to the sump through the sludge return pipe 2 by air blowing through the air pipe 3 using the pressure difference. The return amount of sludge is designed according to 20 times the influent amount, and the overall lifting height is 0.09m. The submerged water depth of the lifting pipe is 0.39m. The total air consumption of the air-lift part is 0.22m 3 / h. The outlets of the 4 sludge return pipes 2 form a vortex, increasing the hydraulic shear force.

[0038] In the early stage of granular domestication, the low-speed vortex flow rate is set to be between 0.1m / s to 1m / s. Within this range, the vortex is sufficient to generate sufficient shear force and turbulence to promote collisions and aggregation between particles, but not too intense to cause particle breakage. Low-speed vortex is conducive to the formation of larger particles while maintaining the sphericity and uniformity of the particles. The temperature of the reactor is controlled at 30-35℃, the pH is in the range of 6-9, and the hydraulic retention time is set to 13.55h. Particle size detection is performed every 3-5 days. After 20 days of operation, the particle size of the sludge is increased from 104um to 215um. Further increase the outlet flow rate of the sludge return pipe 2 to 1m / s to 5m / s. The medium-speed vortex can provide stronger turbulent conditions, which is conducive to the rapid growth and formation of particles. The flow rate in this range can promote effective collisions between particles without causing excessive breakage of particles. Other conditions remain unchanged, and after 34 days, the particle size gradually increases and stabilizes at 1.65mm.

[0039] Example 3: The present application provides a granular sludge biological selector based on short-cut nitrification and anammox, the specific operation steps are as follows:

[0040] The initial design of the reactor is 0.088m 3 / d, into the collection tank. The reactor temperature was controlled at 35±1℃, the pH was controlled between 6.0-9.0, and the hydraulic retention time was 13.55h. The initial influent concentration was COD=3000mg / L, NH4 + -N=900mg / L, TN=1000mg / L, and the preliminary cultivation of PN / A sludge was carried out. After 25 days of operation, the removal rate of COD gradually stabilized at 83%, NH4 + -N and TN was 80%, 80%, respectively.

[0041] The influent NH4 + -N concentration was increased to 2000mg / L, COD=3000mg / L, TN=2500mg / L, and the hydraulic retention time was 13.55h. After 32 days of operation, the removal rates of COD, NH4 + -N and TN gradually stabilized at 83%, 80%, 78%, respectively. The influent concentration was further increased to COD=3000mg / L, NH4 + -N=3000mg / L, TN=3500mg / L, and the influent amount was increased to 9.34m 3 / d. After 35 days of operation, the effluent COD=500mg / L, NH4 + -N=600mg / L, TN=700mg / L. Finally, the granular sludge capable of removing high COD, NH4 + -N was obtained. The sewage was discharged to the next unit through the effluent pipe 5 for deep denitrification, and the final effluent met the Synthetic Ammonia Industrial Water Pollutant Discharge Standard (GB 13458-2013):

[0042] Table 1.2 Synthetic Ammonia Industrial Water Pollutant Discharge Standard

[0043]

[0044] Compared with the EGSB reactor, the present application has the following advantages: (1) Good mixing performance: The present application reduces the height of the upper space of the reactor, and the fluid dynamics is more stable, so that good mixing performance is easily achieved. The reactor with a high aspect ratio is prone to form a horizontal vortex at the bottom due to the large height, resulting in uneven mixing. (2) Flexible operation: The packing density is relatively high, and the microorganisms and substrates are in more sufficient contact, thereby improving the reaction efficiency. At the same time, it is easier to perform manual control and fine adjustment, such as adjusting pH, temperature and oxidation-reduction potential, etc. (3) Short start-up and recovery time: The present application requires less biomass, so the time for starting a new reaction system or recovering when problems occur is relatively short. (4) Low investment and operating cost: The construction and operation cost of the present application is generally lower, and it is more suitable for pilot or small-scale production applications.

[0045] In addition, the present application uses a gas stripping process to return the granular sludge, and the water flow at the outlet of the sludge return pipe 2 is designed in the form of a vortex. Compared with "Hydrodynamic circulation enhanced pneumatic flocculation integrated wastewater treatment device" (CN118084166A) and "Biological selector for cultivating aerobic granular sludge" (CN221093924U), the present application does not need to add additional flocculants and reduces the aeration amount. The micro-bubbles generated during the removal of COD aeration can increase the collision between the small particles. Since the reactor uses a plug flow rising, the sludge is separated from the sewage in the sedimentation tank 6, which will not adversely affect the sludge sedimentation. Compared with other granulation reactors, the present application has the following advantages: (1) Improved efficiency: The gas stripping process utilizes the high fluidity of gas to quickly and effectively transfer granular materials from one place to another, improving the lifting efficiency of the materials. (2) Reduced energy consumption: Compared with traditional mechanical lifting methods, the gas stripping process generally has lower energy consumption because the energy required for gas flow is lower than that for mechanical movement. (3) The gas stripping process can achieve uniform lifting of materials, which helps to maintain the uniformity of the materials during the granulation process, thereby improving the quality of the granules. Strong adaptability: The gas stripping process can adapt to different types and shapes of granular materials. (4) Improved particle uniformity: The vortex water flow can provide higher shear force, which helps to better mix and disperse the raw material particles in water, thereby improving the uniformity of the particles during the granulation process. (5) Promote material mixing: During the granulation process, the vortex water flow can effectively mix different components of the material together, which helps to form a uniform granular structure. (6) Reduce particle size difference: By controlling the intensity of the vortex water flow, the difference in particle size during the granulation process can be reduced, making the granular product more uniform. (7) Reduce energy consumption: Although the vortex increases the shear force of the water flow, by optimizing the vortex design, the granulation effect can be improved without significantly increasing the energy consumption.

[0046] Those skilled in the art can understand that the above embodiments are specific examples of implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, therefore the protection scope of the present application should be limited by the scope defined in the claims.

Claims

1. A granular sludge biological selector based on short-cut nitrification and anaerobic ammonium oxidation, characterized in that, The selector includes: a water collection tank, an inlet pipe (1) and a sludge return pipe (2). The inlet end of the inlet pipe (1) is used to connect to wastewater, and the outlet end extends into the bottom of the water collection tank. An aeration disc (7) is provided at the bottom of the water collection tank, and a sedimentation tank (6) is provided above the aeration disc (7). The sedimentation tank (6) is located in the water collection tank. An air pipe (3) is introduced into the sedimentation tank (6) from the top. A water collection tank (4) is located in the middle of the sedimentation tank (6). A water outlet pipe (5) leading to the outside of the water collection tank is connected to the bottom of the water collection tank (4). The inlet end of the sludge return pipe (2) extends into the bottom of the sedimentation tank (6), and the outlet end extends into the bottom of the water collection tank; wherein, there are multiple sludge return pipes (2), and the outlet ends of the multiple sludge return pipes (2) are arranged in a vortex form to increase the shear force of the water flow to facilitate granulation and to make the sewage and sludge mix evenly.

2. The granular sludge biological selector based on short-cut nitrification and anaerobic ammonium oxidation according to claim 1, characterized in that, The water collection tank and the sedimentation tank (6) are equipped with a DO probe (15) and a pH probe (16) controlled by the WTW host (14).

3. The granular sludge biological selector based on short-cut nitrification and anaerobic ammonium oxidation according to claim 2, characterized in that, The water inlet pipe (1) is also connected to a pH adjuster storage tank (10).

4. The granular sludge biological selector based on short-cut nitrification and anaerobic ammonium oxidation according to claim 3, characterized in that, A liquid flow meter (11) is installed between the pH adjuster storage tank (10) and the water inlet pipe (1).

5. The granular sludge biological selector based on short-cut nitrification and anaerobic ammonium oxidation according to claim 4, characterized in that, The pH adjuster storage tank (10) is also equipped with a dosing pump (9) at its outlet, and the dosing pump (9) is controlled by the control system (8).

6. The granular sludge biological selector based on short-cut nitrification and anaerobic ammonium oxidation according to claim 5, characterized in that, The bottom of the water collection tank is connected to the air outlet of the blower (13), and an air flow meter (12) is installed between the blower (13) and the water collection tank; the blower (13) is controlled by the control system (8).

7. The granular sludge biological selector based on short-cut nitrification and anaerobic ammonium oxidation according to claim 6, characterized in that, The air pipe (3) is also connected to a blower (13), and the blower (13) and the air pipe (3) are equipped with an air flow meter (12); the blower (13) is controlled by the control system (8).

8. A wastewater treatment method, characterized in that, This method is applied in a granular sludge biological selector based on short-cut nitrification anaerobic ammonium oxidation as described in any one of claims 1 to 7, the method comprising: Wastewater enters the collection tank through the inlet pipe (1), where aeration discs (7) aerate to remove most of the COD and ammonia nitrogen (NH4+). + -N) is converted into nitrite (NO2) - -N); The sewage in the collection tank enters the sedimentation tank (6) in an upflow manner along with the water flow; The particulate sludge in the sewage is separated to the bottom through the sedimentation tank (6), and the treated sewage enters the outlet pipe (5) from the collection tank (4) and is discharged. The sludge at the bottom of the sedimentation tank (6) enters the sludge return pipe (2) through the airflow difference generated by the aeration of the air pipe (3) and returns to the bottom of the collection tank.

9. The wastewater treatment method according to claim 8, characterized in that, The method also includes: a DO probe (15) and a pH probe (16) to monitor the sewage in the collection tank in real time, and control the DO of the sewage to be less than 0.5 and the pH value to be between 6 and 9; When the wastewater quality does not meet the requirements, the control system (8) starts the pH adjuster storage tank (10), controls the dosing pump (9) to add chemicals to the wastewater through the liquid flow meter (11), and / or ventilates the wastewater through the air flow meter (12) and the blower (13).

10. The application of the granular sludge biological selector based on short-cut nitrification anaerobic ammonium oxidation as described in any one of claims 1 to 7 in the field of high ammonia nitrogen wastewater treatment.

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