Induced granulation type oxidation ditch reactor for continuous flow aerobic granular sludge culture and use method thereof

Abstract

The invention relates to an induced granulation type oxidation ditch reactor for continuous flow aerobic granular sludge culture and a use method thereof, the induced granulation type oxidation ditch reactor comprises a reaction chamber, the reaction chamber is divided into an aerobic zone and an anoxic zone by a baffle plate, the top of the aerobic zone is connected with a support, a selector is arranged above the support, and the selector is communicated to the bottom of the aerobic zone through a selector water outlet pipe; the bottom of the side wall of one end of the selector is communicated with a sewage inlet pipe, a multi-tank sedimentation tank is arranged on one side in the anoxic zone and communicated with the selector through a gas stripping pipe, a sedimentation tank inlet is formed in one end of the multi-tank sedimentation tank, and a reactor water outlet pipe is arranged at the other end of the multi-tank sedimentation tank; the selector, the multi-tank sedimentation tank and the gas stripping system are integrated, sludge with different particle sizes or sedimentation properties is screened through the multi-tank sedimentation tank, and a sludge-water mixture directionally flows back to different positions in the selector in a gas stripping manner, so that the sludge with small particle sizes or poor sedimentation properties is mixed with high-matrix sewage to strengthen a satiation stage; and the large-particle-size sludge flows back to the low-matrix area, so that particle formation and stable operation of the system are promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to an induced granulation type oxidation ditch reactor for continuous flow aerobic granular sludge cultivation and a use method thereof. Background Art

[0002] Activated sludge technology is one of the most widely used wastewater treatment technologies, with a history of nearly a century. Early activated sludge processes primarily relied on suspended activated sludge systems, which produced flocculent sludge. Currently, most wastewater treatment plants still primarily utilize flocculent suspended sludge systems. However, with the acceleration of urbanization and increasingly stringent wastewater discharge standards, existing wastewater treatment facilities are facing increasing pressure to meet current emission targets for nitrogen and phosphorus removal. Therefore, there is an urgent need for technological upgrades in wastewater treatment plants to improve treatment efficiency and meet higher emission standards.

[0003] As a new biological wastewater treatment technology, aerobic granular sludge (AGS) technology is one of the ideal choices for upgrading wastewater treatment plants due to its advantages such as efficient organic matter and nutrient removal, high reactor volume load, small footprint, excellent sludge settling performance and strong resistance to shock loads.

[0004] However, in long-term applications, AGS technology mainly relies on sequencing batch reactors (SBRs) for cultivation and research. Although SBRs can effectively cultivate aerobic granular sludge, their operation and management are complex and are only suitable for sewage treatment plants with smaller water volumes. With the expansion of sewage treatment facilities and the increase in treatment capacity, many sewage treatment plants currently mainly use large-scale continuous flow systems. In this context, promoting sludge granulation through in-situ transformation rather than transforming into an SBR system has higher economic benefits and practical application value. Therefore, research on AGS technology in continuous flow reactors (CFRs) is particularly important and has practical significance.

[0005] The Chinese invention patent application number CN202410498211.6 discloses a method for treating wastewater and promoting sludge granulation by combining a granulation fluidized bed and a bioreactor process. This method uses front-end pretreatment to screen the raw water using reagents and crystal seeds, thereby providing the bioreactor with an environment suitable for the growth of granular sludge. In addition, the fluidized bed can enrich and recover insoluble substances that are difficult to biologically treat at the front end, further optimizing the sewage treatment process. However, although this technology can enhance the cultivation effect of granular sludge, in large-scale sewage treatment plants, the chemical agent addition and front-end treatment involved are relatively complicated, increasing operation and maintenance costs. Summary of the Invention

[0006] In order to overcome the deficiencies of the above-mentioned prior art, the object of the present invention is to provide an induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation and a method for using the same. The reactor is an integrated reactor, in which a selector, a multi-trough sedimentation tank and an air lift pipe are integrated in the reaction chamber. The sludge with different sedimentation performance or particle size is screened through the multi-trough sedimentation tank, and the mud-water mixture is returned to different positions in the selector through the air lift pipe. The activated sludge can be screened and differentially returned based on the sludge particle size or sedimentation performance, so that small-particle sludge or sludge with poor sedimentation performance can be enhanced in the satiation stage in the high substrate concentration area, and large-particle sludge or sludge with good sedimentation performance can be satiation in the low substrate area, thereby inducing the sludge to accelerate granulation. The reactor has the advantages of compact structure, high particle formation efficiency, strong operation stability, saving investment and land occupation, etc.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] An induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation includes a reaction chamber 1, which is divided into an aerobic zone 15 and an anoxic zone 16 that are interconnected by a baffle 2. A plurality of horizontal supports 14 are connected to the top of the aerobic zone 15, and a selector 3 is provided above the support 14. The selector 3 is connected to the bottom of the aerobic zone 15 through a selector outlet pipe 7. The bottom of one end side wall of the selector 3 is connected to the sewage inlet pipe 5. A multi-trough sedimentation tank 4 is provided on one side of the anoxic zone 16. The multi-trough sedimentation tank 4 is connected to the selector 3 through an air stripping pipe 10. A sedimentation tank inlet 9 is provided above one end side wall of the multi-trough sedimentation tank 4, and a reactor outlet pipe 13 is provided above the other end side wall of the multi-trough sedimentation tank 4.

[0009] A plurality of evenly arranged triangular baffles 6 are provided between the inner walls of the selector 3 . The top of one side wall of the selector 3 is connected to the inlet end of the selector outlet pipe 7 . The selector outlet 8 of the selector outlet pipe 7 is connected to the bottom of the aerobic zone 15 .

[0010] A plurality of sedimentation tanks 12 are provided at the bottom of the multi-tank sedimentation tank 4, and an air lift pipe 10 is provided above each sedimentation tank 12. The air lift pipe 10 is fixed on the inner wall of the multi-tank sedimentation tank 4, and the bottom end of the air lift pipe 10 is connected to the top of the gas injection pipe 11. The bottom end of the gas injection pipe 11 is connected to the top of the bottom of the sedimentation tank 12. The top of the air lift pipe 10 is bent and connected to the top of the selector 3. A bottom inclined pipe 17 corresponding to the air lift pipe 10 is provided below each sedimentation tank 12, and the bottom inclined pipe 17 is connected to the anoxic zone 16.

[0011] The selector 3 is configured to be rectangular.

[0012] The selector 3 is a plug flow reactor.

[0013] The present invention also provides a method for using an induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation, comprising the following steps:

[0014] Step 1: The sewage to be treated enters the selector 3 through the bottom sewage inlet pipe 5 and flows through the triangular baffle 6. At the same time, a portion of the mud-water mixture in the sedimentation tank 12 flows back into the selector 3 through the air stripping pipe 10, mixes with the sewage to be treated, and then flows into the bottom of the aerobic zone 15 through the selector outlet pipe 7;

[0015] In step 2, the mud-water mixture in the reaction chamber 1 undergoes biochemical reactions in the aerobic zone 15 and the anoxic zone 16 under the action of water thrust, and then enters the multi-tank sedimentation tank 4 from the sedimentation tank inlet 9 to screen the sludge with different particle sizes or sedimentation properties. Due to the action of water thrust and gravity, the sludge sinks into the sedimentation tank 12, and solid-liquid separation is carried out in the sedimentation tank 12. A part of the mud-water mixture flows into the bottom of the anoxic zone 16 through the bottom inclined pipe 17 of the sedimentation tank 12, and the other part of the mud-water mixture flows back to the selector 3 through the air stripping pipe 10. After the mud and water separation is achieved through the multi-tank sedimentation tank 4, the treated sewage is discharged from the reaction chamber 1 through the reactor outlet pipe 13.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. Screening of sludge of different particle sizes or settling properties. The present invention utilizes a multi-tank sedimentation tank 4. When the sludge-water mixture flows into the multi-tank sedimentation tank 4, gravity causes a sorting and clarification process. Sludge deposited in the sedimentation tank 12 at the inlet of the multi-tank sedimentation tank 4 has a larger particle size or better settling properties, while sludge deposited in the sedimentation tank 12 near the outlet typically has a smaller particle size or poorer settling properties. The multi-tank sedimentation tank 4 effectively screens sludge by particle size or settling properties.

[0018] 2. Directed cultivation of sludge with different particle sizes or sedimentation properties. As described in the first point of the beneficial effect, the sludge characteristics in different sedimentation tanks 12 are different. An air lift pipe 10 is designed above each sedimentation tank 12. After the sludge is air lifted and returned to the selector 3, it is mixed with sewage in the selector 3. Since the selector 3 is a plug flow reactor, the concentration of the matrix and microorganisms varies with space, and the concentration of the sewage matrix is ​​different at different positions. Therefore, after the sludge in different sedimentation tanks 12 is air lifted and returned, it is mixed with sewage with different matrix concentrations. The sludge in the sedimentation tank 12 near the water outlet is usually smaller in particle size or has poor sedimentation performance. When this part of the sludge is returned to the selector 3, there is no other sludge at the front end to react with the sewage. Therefore, the sewage matrix concentration it contacts is the highest. Under anoxic conditions, the satiation stage of the microorganisms is enhanced, and the granulation of small sludge is promoted. Similarly, the sedimentation tank 12 near the inlet of the multi-tank sedimentation tank 4 typically returns sludge with larger particle sizes or better settling properties. After this sludge returns, it is close to the outlet of the selector 3, where the COD concentration in the substrate is low, the sludge residence time is short, and the starvation phase is short. This allows sludge with smaller particle sizes or poorer settling properties to come into contact with more substrate, while sludge with larger particle sizes or better settling properties comes into contact with less substrate. This allows for targeted cultivation of sludge with different characteristics, optimizes the particle size distribution in the reactor, enhances system stability, and promotes sludge granulation.

[0019] 3. In addition to the characteristics of general oxidation ditches, the present invention also has the following advantages: by integrating a multi-tank sedimentation tank 4, sludge sedimentation is achieved. The process flow is short, with fewer structures and equipment, and no primary sedimentation tank, regulating tank, or separate secondary sedimentation tank is required. The solid-liquid separation effect is better than that of a traditional secondary sedimentation tank, which is conducive to the stable operation of the system within a larger flow rate or concentration range. The mud-water mixture in the multi-tank sedimentation tank 4 is refluxed through the integrated air lift pipe 10, and there is no need to set up a separate reflux pump room, thus avoiding the need to build a sludge pump station and supporting pipeline network. It significantly saves investment costs and floor space, and improves the adaptability and economic characteristics of the project.

[0020] 4. The present invention uses a multi-tank sedimentation tank 4 to screen sludge of different particle sizes or settling properties, and returns the sludge with different characteristics to the selector 3 through the air lift pipe 10, directionally strengthening the satiation stage of different sludges, promoting sludge granulation, and maintaining system stability.

[0021] In summary, the present invention integrates a selector 3, a multi-tank sedimentation tank 4, and an air lift pipe 10 within a reaction chamber 1, establishing a sorting and directional recirculation mechanism based on differences in sludge particle size or settling performance. This allows small-sized sludge or sludge with poor settling performance to undergo an enhanced satiation phase in high-substrate concentration areas, while large-sized sludge or sludge with good settling performance is satiationed in low-substrate areas, thereby inducing accelerated sludge granulation. This system offers the advantages of a simple process flow, high particle formation efficiency, strong operational stability, and reduced investment and space requirements. It is suitable for the efficient cultivation and engineering application of aerobic granular sludge under continuous flow conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a front view of the overall structure of the present invention.

[0023] Figure 2 It is a top view of the overall structure of the present invention.

[0024] Figure 3 It is a three-dimensional diagram of the overall structure of the present invention.

[0025] Figure 4 is a pollutant removal capability diagram of an embodiment of the present invention; wherein, Figure 4 (a) is ammonia nitrogen (NH4 + -N) removes the capability graph, Figure 4 (b) is nitrite nitrogen (NO2 - -N) removes the capability graph, Figure 4 (c) is nitrate nitrogen (NO3 - -N) removes the capability graph, Figure 4 (d) is the COD removal capacity diagram.

[0026] Figure 5 is the particle size distribution of the embodiment of the present invention.

[0027] Figure 6 Graph showing particle size distribution in each sedimentation tank according to an embodiment of the present invention.

[0028] Among them, 1. reaction chamber; 2. baffle; 3. selector; 4. multi-tank sedimentation tank; 5. water inlet pipe; 6. triangular baffle; 7. selector outlet pipe; 8. selector outlet; 9. sedimentation tank inlet; 10. gas lift pipe; 11. gas injection pipe; 12. sedimentation tank; 13. reactor outlet pipe; 14. bracket; 15. aerobic zone; 16. anoxic zone; 17. bottom inclined pipe. DETAILED DESCRIPTION

[0029] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are therefore only examples and are not intended to limit the scope of protection of the present invention.

[0030] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0031] In the description of this application, it should be understood that terms such as "above", "left", "right", "bottom", "top", and "inside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not simply mean or imply that the device or element referred to must have a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0032] In addition, the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features.

[0033] In the description of this invention, there are no fixed requirements for the size and structure of the selector. The core purpose of the selector used in this invention is to ensure that the sludge from different sedimentation tanks can be exposed to different concentrations of substrate when it is returned to the selector. Those skilled in the art will be able to modify the size and structure of the selector according to specific circumstances. The selector sizes and structures given in this application are merely for the purpose of facilitating and simplifying the description of the invention and should not be construed as limiting the invention.

[0034] In the description of the present invention, "a plurality" means more than two, unless otherwise specifically defined. The number of sedimentation tanks 12 of the multi-tank sedimentation tank 4 is not fixed to 5, and is only 5 in the embodiment of this application.

[0035] In this application, unless otherwise specified or limited, the terms "connection" and "fixed" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0036] The present invention provides an induced granulation oxidation ditch reactor for continuous-flow aerobic granular sludge cultivation and its use method. A multi-tank sedimentation tank is built into a reaction chamber 1, and sludge is returned to a selector 3 via an air stripping pipe 10. The sludge is screened in the multi-tank sedimentation tank 4. After air stripping and return, sludge of different particle sizes or settling properties is exposed to substrates of varying concentrations, enhancing the sludge's satiation stage and achieving targeted sludge cultivation.

[0037] like Figure 1 、 Figure 2As shown, an induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation includes a reaction chamber 1, which is divided into an aerobic zone 15 and an anoxic zone 16 that are interconnected by a baffle 2. A plurality of horizontal supports 14 are connected to the top of the aerobic zone 15, and a selector 3 is provided above the support 14. The selector 3 is connected to the bottom of the aerobic zone 15 through a selector outlet pipe 7. The bottom of one end side wall of the selector 3 is connected to the sewage inlet pipe 5. A multi-trough sedimentation tank 4 is provided on one side of the anoxic zone 16. The multi-trough sedimentation tank 4 is connected to the selector 3 through an air lift pipe 10. A sedimentation tank inlet 9 is provided above the side wall of one end of the multi-trough sedimentation tank 4, and a reactor outlet pipe 13 is provided above the side wall of the other end of the multi-trough sedimentation tank 4.

[0038] like Figure 3 As shown, a plurality of evenly arranged triangular baffles 6 are provided between the inner walls of the selector 3 , the top of the side wall at one end of the selector 3 is connected to the inlet end of the selector outlet pipe 7 , and the selector outlet 8 of the selector outlet pipe 7 is connected to the bottom of the aerobic zone 15 .

[0039] The triangular baffle 6 is used to enhance the hydraulic shear force in the selector 3, increase the mixing reaction time of the activated sludge and the sewage to be treated, strengthen the satiation stage, and promote the granulation of the activated sludge.

[0040] A plurality of sedimentation tanks 12 are provided at the bottom of the multi-tank sedimentation tank 4, and an air lift pipe 10 is provided above each sedimentation tank 12. The air lift pipe 10 is fixed on the inner wall of the multi-tank sedimentation tank 4, and the bottom end of the air lift pipe 10 is connected to the top of the gas injection pipe 11. The bottom end of the gas injection pipe 11 is connected to the top of the bottom of the sedimentation tank 12. The top of the air lift pipe 10 is bent and connected to the top of the selector 3. A bottom inclined pipe 17 corresponding to the air lift pipe 10 is provided below each sedimentation tank 12, and the bottom inclined pipe 17 is connected to the anoxic zone 16.

[0041] The selector 3 is configured to be rectangular.

[0042] The selector 3 is a plug flow reactor.

[0043] The number of sedimentation tanks 12, air stripping pipes 10 and bottom inclined pipes 17 in the multi-tank sedimentation tank 4 can be the same, and the specific number is not fixed. The number of sedimentation tanks 12, air stripping pipes 10 and bottom inclined pipes 17 can be set appropriately according to the specific situation.

[0044] There is no fixed requirement for the internal structure of the selector 3, and the structure of the selector 3 can be modified according to specific circumstances.

[0045] In addition, the multi-tank sedimentation tank 4 of the present invention can be modified as an assembled equipment with a simple process and a short construction period. By adding it, the sewage treatment plant can be upgraded.

[0046] The present invention also provides a method for using an induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation, comprising the following steps:

[0047] Step 1: The sewage to be treated enters the selector 3 through the bottom sewage inlet pipe 5 and flows through the triangular baffle 6. At the same time, a portion of the mud-water mixture in the sedimentation tank 12 flows back into the selector 3 through the air stripping pipe 10, mixes with the sewage to be treated, and then flows into the bottom of the aerobic zone 15 through the selector outlet pipe 7;

[0048] In step 2, the mud-water mixture in the reaction chamber 1 undergoes biochemical reactions in the aerobic zone 15 and the anoxic zone 16 under the action of water thrust, and then enters the multi-tank sedimentation tank 4 from the sedimentation tank inlet 9 to screen the sludge with different particle sizes or sedimentation properties. Due to the action of water thrust and gravity, the sludge sinks into the sedimentation tank 12, and solid-liquid separation is carried out in the sedimentation tank 12. A part of the mud-water mixture flows into the bottom of the anoxic zone 16 through the bottom inclined pipe 17 of the sedimentation tank 12, and the other part of the mud-water mixture flows back to the selector 3 through the air stripping pipe 10. After the mud and water separation is achieved through the multi-tank sedimentation tank 4, the treated sewage is discharged from the reaction chamber 1 through the reactor outlet pipe 13.

[0049] Example

[0050] In this embodiment, five sedimentation tanks are provided in the multi-tank sedimentation tank.

[0051] The reactor operating parameters are as follows:

[0052] Table 1 Oxidation ditch system and its operating conditions

[0053]

[0054]

[0055] During the operation of the reactor, the gas flow rate of the five gas stripping processes was controlled at 1±0.2L / min. After 46 days of operation, the water quality was as follows: Figure 4 In this embodiment, ammonia nitrogen (NH4 + -N) and chemical oxygen demand (COD) removal performance was stable. The effluent concentration of ammonia nitrogen remained at a low level throughout the experiment. On the third day, the effluent concentration was 0.25 mg / L, showing an extremely high removal efficiency. As the operation time increased, the removal rate of ammonia nitrogen remained above 95%. On the 46th day, the effluent concentration dropped to 0.02 mg / L, achieving a nearly complete removal effect. Figure 4 (a) shows that the system of the present invention can stably and efficiently remove ammonia nitrogen and meet the requirements of sewage treatment. For the removal of COD, Figure 4As shown in (b), the influent COD concentration was maintained between 370-403 mg / L. After treatment, the effluent COD concentration was below 50 mg / L, and the maximum removal rate could reach 89.85%. On some days, especially on the 35th day, the COD removal rate fluctuated and dropped to 57.16%. However, overall, the COD removal effect was still stable and efficient, fully meeting the requirements of wastewater treatment. At the same time, nitrite nitrogen (NO2 - -N) and nitrate nitrogen (NO3 - -N) removal is more complicated. The nitrite nitrogen concentration in the effluent reached 1.6 mg / L and 1.8 mg / L on the 23rd and 35th days respectively, indicating that there are certain fluctuations in the removal of nitrite nitrogen during the treatment process. Figure 4 (c) As shown. The nitrate nitrogen concentration in the effluent is relatively high, as shown in Figure 4 (d) shows that the highest is 6.31 mg / L (day 46). In summary, the system in this embodiment shows excellent stability and efficiency in the removal of ammonia nitrogen and COD, while there are certain fluctuations in the removal of nitrite nitrogen and nitrate nitrogen, which may be related to factors such as the biological reaction conditions in the reactor and changes in sewage water quality. Overall, the reactor of the present invention can effectively deal with the removal of multiple pollutants and meet the needs of daily sewage treatment.

[0056] like Figure 5As shown in the figure, the sludge particle size distribution reflects the changes in the sludge morphology and structure within the reactor. It can be seen that the average particle size of the inoculum sludge was 46.91 μm, with particles primarily concentrated in the 10-50 μm range. The proportion of sludge larger than 100 μm was relatively low, at only 6.02%. This indicates that the particles in the inoculum sludge were relatively small, with the majority falling within the smaller particle size range. As the operation progressed, the particle size gradually increased. On the fourth day, the average particle size increased to 57.29 μm. The proportion of sludge 10-50 μm remained significant, but the proportion of sludge larger than 100 μm increased to 10.68%, indicating the beginning of granulation. By the 12th day, the average particle size had further increased to 65.44 μm, and the proportion of sludge larger than 100 μm had further increased to 15.62%, indicating the gradual emergence of granulation. When the system was running for 39 days, the average particle size reached 85.22μm, and the proportion of sludge larger than 100μm was 21.65%, and the proportion of large particles increased significantly. On the 42nd day, although the average particle size dropped slightly to 78.82μm, the proportion of sludge larger than 100μm remained at 20.81%. On the 43rd and 46th days, the average particle size reached 94.55μm and 92.55μm respectively, and the proportion of sludge larger than 100μm was 23.06% and 22.45% respectively, indicating that the granulation process was further strengthened in the later stage and the proportion of large-size particles increased significantly. Overall, as the reactor operation time increased, the average particle size of the sludge gradually increased, and the proportion of sludge larger than 100μm increased significantly, reflecting the stable cultivation process of granulated sludge in the system. Finally, on the 46th day, the proportion of particles larger than 100μm was 22.45%, indicating that the reactor of the present invention achieves the cultivation of granular sludge.

[0057] At the same time, if Figure 6Figure 2 shows the particle size distribution at different locations within the reactor on day 40. Sludge sampling locations 1-5 are numbered 1, near the inlet of the multi-tank sedimentation tank, and 5, near the outlet. In sedimentation tank 1, the average sludge particle size was 89.98 μm, and particles larger than 100 μm accounted for 21.45%, indicating larger sludge particle size and a high degree of granulation at this location. The average sludge particle size in sedimentation tanks 2 and 3 increased further, reaching 86.23 μm and 90.76 μm, respectively. The proportions of sludge larger than 100 μm were 21.12% and 22.32%, respectively, indicating stable sludge granulation at these locations. In contrast, the average sludge particle size in sedimentation tank 4 was 81.11 μm, with sludge larger than 100 μm accounting for 19.72%. While the particle size decreased slightly, the granulation level remained high. While the sludge in sedimentation tank 5 had an average particle size of 67.75 μm and sludge smaller than 50 μm accounted for 42.12%, sludge larger than 100 μm accounted for 14.69%, indicating a certain degree of granulation. Compared to the sludge in the sedimentation tank, the sludge particle sizes in the selector and aerobic zones showed significant differences. The average particle size in the selector was 72.83 μm, and the proportion of sludge larger than 100 μm was 16.87%, indicating a low degree of sludge granulation in this location. In contrast, the average particle size in the aerobic zone was 86.55 μm, and the proportion of sludge larger than 100 μm was 21.12%, demonstrating a higher degree of granulation, indicating that the granulation level in the aerobic zone is more stable and mature than in other locations. Overall, the sludge particle size distribution varied significantly between different locations within the reactor, with the aerobic zone exhibiting the highest degree of granulation, while the selector and other sedimentation tanks showed lower granulation levels, reflecting differences in the granulation process and stability of the sludge at different locations.

[0058] According to the above experimental data, the sludge can be screened by particle size or sedimentation performance through the multi-tank sedimentation tank 4, so that the saturation stage of different sludges can be strengthened through air stripping reflux, thereby improving system stability and accelerating sludge granulation.

[0059] The above description is merely a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto. Sludge screening in multiple sedimentation tanks and recirculation to different inlet locations enhances the satiation phase and accelerates sludge granulation. Any modifications or substitutions readily conceivable by those skilled in the art within the technical scope of this invention are intended to be encompassed within the scope of this invention.

Claims

1. An induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation, characterized in that: The invention comprises a reaction chamber (1), wherein the reaction chamber (1) is divided into an aerobic zone (15) and an anoxic zone (16) which are interconnected by a baffle (2); a plurality of horizontal brackets (14) are connected to the top of the aerobic zone (15); a selector (3) is arranged above the bracket (14); the selector (3) is connected to the bottom of the aerobic zone (15) through a selector outlet pipe (7); the bottom of one end side wall of the selector (3) is connected to a sewage inlet pipe (5); a multi-trough sedimentation tank (4) is arranged on one side inside the anoxic zone (16); the multi-trough sedimentation tank (4) is connected to the selector (3) through an air stripping pipe (10); a sedimentation tank inlet (9) is arranged above one end side wall of the multi-trough sedimentation tank (4); and a reactor outlet pipe (13) is arranged above the other end side wall of the multi-trough sedimentation tank (4).

2. The induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation according to claim 1, characterized in that: A plurality of evenly arranged triangular baffles (6) are provided between the inner walls of the selector (3); the top of one side wall of the selector (3) is connected to the inlet end of the selector outlet pipe (7); and the selector outlet (8) of the selector outlet pipe (7) is connected to the bottom of the aerobic zone (15).

3. The induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation according to claim 1, characterized in that: A plurality of sedimentation tanks (12) are provided at the bottom of the multi-tank sedimentation tank (4), and an air stripping pipe (10) is provided above each sedimentation tank (12). The air stripping pipes (10) are fixed on the inner wall of the multi-tank sedimentation tank (4), and the bottom end of the air stripping pipe (10) is connected to the top end of the gas injection pipe (11). The bottom end of the gas injection pipe (11) is connected to the top of the bottom of the sedimentation tank (12), and the top end of the air stripping pipe (10) is bent and connected to the top of the selector (3). A bottom inclined pipe (17) corresponding to the air stripping pipe (10) is provided below each sedimentation tank (12), and the bottom inclined pipe (17) is connected to the anoxic zone (16).

4. An induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation according to claim 1, 2 or 3, characterized in that: The selector (3) is configured in a rectangular shape.

5. An induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation according to claim 1, 2 or 3, characterized in that: The selector (3) is a plug flow reactor.

6. A method for using an induced granulation oxidation ditch reactor for continuous flow aerobic granular sludge cultivation, characterized in that: The following steps are involved: Step 1: The sewage to be treated enters the selector (3) through the bottom sewage inlet pipe (5) and flows through the triangular baffle (6). At the same time, a portion of the mud-water mixture in the sedimentation tank (12) flows back into the selector (3) through the air stripping pipe (10), mixes with the sewage to be treated, and then flows into the bottom of the aerobic zone (15) through the selector outlet pipe (7); In step 2, the mud-water mixture in the reaction chamber (1) undergoes biochemical reactions in the aerobic zone (15) and the anoxic zone (16) under the action of the water flow thrust, and then enters the multi-trough sedimentation tank (4) from the sedimentation tank inlet (9), where sludge with different particle sizes or sedimentation properties is screened. Due to the action of the water flow thrust and gravity, the sludge sinks into the sedimentation tank (12), where solid-liquid separation is performed in the sedimentation tank (12). A portion of the mud-water mixture flows into the bottom of the anoxic zone (16) through the bottom inclined pipe (17) of the sedimentation tank (12), and the other portion of the mud-water mixture flows back to the selector (3) through the air stripping pipe (10). After the mud-water separation is achieved through the multi-trough sedimentation tank (4), the treated sewage is discharged from the reaction chamber (1) through the reactor outlet pipe (13).

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