Method for improving biochemical treatment performance of activated sludge, in-situ expansion device of sewage treatment system and sewage treatment system

Abstract

The invention discloses a method for improving biochemical treatment performance of activated sludge, an in-situ expansion device of a sewage treatment system and the sewage treatment system. The method for improving the biochemical treatment performance of the activated sludge comprises the following steps: inputting the activated sludge into a first separation cavity of a first-stage separation unit so as to separate organic matters and inorganic matters in the activated sludge through spiral movement of the activated sludge in the first separation cavity, the concentration of inorganic matters in the activated sludge discharged from the first overflow port of the first-stage separation unit is reduced, and the concentration of organic matters is improved; and inputting the activated sludge discharged from the first overflow port into a second separation cavity of the second-stage separation unit, so as to recover the activated sludge enriched with nitrifying bacteria from a second underflow port of the second-stage separation unit through the spiral motion of the activated sludge in the second separation cavity. The method has good effects of removing inorganic particles in the activated sludge and recycling and enriching nitrifying bacteria, the treatment load of a sewage treatment system can be effectively improved, and in-situ synergy and capacity expansion of the sewage treatment system are achieved.

Description

Technical Field

[0001] The present application relates to the field of water treatment technology, and specifically to a method for improving the biochemical treatment performance of activated sludge, an in-situ expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge, and a sewage treatment system. Background Art

[0002] Since urban sewage has the water quality characteristics of high inorganic suspended solids concentration and low carbon-nitrogen ratio, the improvement of the operating efficiency of the activated sludge process still faces huge challenges. A large amount of inorganic particulate matter in sewage enters the biochemical treatment unit, which not only reduces the microbial share per unit volume, but also accelerates the wear of mechanical equipment, seriously affecting the performance and efficiency of the biochemical treatment unit. In addition, the existing activated sludge method has problems such as small treatment load, long sludge age, and unstable ammonia nitrogen removal rate, which are mainly attributed to the low content of nitrifying bacteria with long generation cycles in the sludge flocs. Therefore, it is urgent to develop a method to improve the biochemical treatment effect and treatment load of sewage treatment plants and promote the improvement of quality and efficiency of urban sewage treatment. Summary of the invention

[0003] The present application provides a method for improving the biochemical treatment performance of activated sludge to overcome the problems of low ratio of mixed liquor volatile suspended solids (MLVSS) to mixed liquid suspended solids (MLSS) and small proportion of nitrifying bacteria in the activated sludge of existing urban sewage treatment systems.

[0004] The present application provides a method for improving the biochemical treatment performance of activated sludge, comprising:

[0005] Inputting activated sludge from a first feed port of a first-stage separation unit into a first separation chamber of the first-stage separation unit, so that the organic matter and the inorganic matter in the activated sludge are separated by spiral motion of the activated sludge in the first separation chamber, so that the concentration of inorganic matter in the sludge discharged from a first underflow port of the first-stage separation unit is increased and the concentration of organic matter is decreased, and the concentration of inorganic matter in the activated sludge discharged from a first overflow port of the first-stage separation unit is decreased and the concentration of organic matter is increased;

[0006] The activated sludge discharged from the first overflow port of the first-stage separation unit is input into the second separation chamber of the second-stage separation unit from the second feed port of the second-stage separation unit, so that the activated sludge enriched with nitrifying bacteria can be recovered from the second underflow port of the second-stage separation unit through the spiral movement of the activated sludge in the second separation chamber.

[0007] The present application also provides an in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge, comprising:

[0008] A first-stage separation unit, comprising a first separation chamber, and a first feed port, a first underflow port and a first overflow port connected to the first separation chamber, wherein the first-stage separation unit is configured to separate organic matter from inorganic matter in the activated sludge by spiral motion of the activated sludge input into the first separation chamber from the first feed port, so that the concentration of inorganic matter in the activated sludge discharged from the first overflow port is reduced and the concentration of organic matter is increased; and

[0009] The second-stage separation unit has a second separation chamber, and a second feed port, a second underflow port and a second overflow port connected to the second separation chamber, and the first overflow port is connected to the second feed port. The second-stage separation unit is configured to recover the activated sludge enriched with nitrifying bacteria from the second underflow port through the spiral movement of the activated sludge input into the second separation chamber from the second feed port.

[0010] The present application also provides a sewage treatment system, including the above-mentioned sewage treatment system in-situ expansion device for improving the biochemical treatment performance of activated sludge.

[0011] Compared with the prior art, this application has the following technical effects:

[0012] 1. Based on the density and morphology differences between organic matter and inorganic matter, and using the composite principles of gravity, centrifugation, and expansion, the activated sludge is treated by the first-stage separation unit to achieve rapid separation of organic matter and inorganic matter in the activated sludge during the multiphase fluid flow process, thereby reducing the concentration of inorganic particles in the activated sludge, increasing the MLVSS in the activated sludge, and thereby increasing the share of microorganisms per unit volume, effectively improving the purification function of the biochemical treatment unit.

[0013] 2. The density of nitrifying bacteria is generally higher than that of conventional heterotrophic microorganisms, and their flocs show higher structural stability. Therefore, by taking advantage of the density difference between flocs, the activated sludge treated by the second-stage separation unit can increase the abundance of nitrifying bacteria in the activated sludge, improve the ammonia nitrogen removal efficiency in the aeration tank, and at the same time reduce the sludge age contradiction between nitrifying bacteria and phosphorus removal bacteria, thereby enhancing the denitrification and phosphorus removal performance of the activated sludge method.

[0014] 3. The two-stage separation units (first-stage separation unit and second-stage separation unit) are operated in series. The first-stage separation unit can separate inorganic matter from organic matter and improve the MLVSS / MLSS value in the activated sludge discharged from the first overflow port. In addition, the friction shearing effect between different particles and between the particles and the inner wall of the first separation chamber in the cyclone field of the first-stage separation unit can separate the bacterial flocs of different microorganisms from each other, which is beneficial to the enrichment of nitrifying bacteria in the second-stage separation unit. Therefore, the activated sludge discharged from the first overflow port of the first-stage separation unit is processed by the second-stage separation unit, and the abundance of nitrifying bacteria in the activated sludge discharged from the second underflow port of the second-stage separation unit can be further improved.

[0015] 4. The activated sludge is treated by two-stage cascade separation units, and the content of microorganisms and nitrifying bacteria in the activated sludge is effectively improved, which can increase the utilization rate of oxygen in the activated sludge, thereby reducing the aeration energy consumption of sewage treatment.

[0016] 5. The in-situ expansion device for the sewage treatment system of the embodiment of the present application has good universality and can be applied to all biochemical processes of the existing urban sewage treatment system. It has good operating effects on the removal of inorganic particulate matter in the activated sludge of different biochemical processes and the recovery and enrichment of nitrifying bacteria.

[0017] 6. The in-situ expansion device of the sewage treatment system of the embodiment of the present application has the advantages of simple structure, high separation efficiency, low operation and maintenance costs, and no need to add chemicals. It is an efficient, low-consumption and green in-situ expansion device for the sewage treatment system that improves the biochemical treatment performance of activated sludge.

[0018] Other features and advantages of the present application will be set forth in the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0020] Figure 1 A schematic diagram of a process for improving the biochemical treatment performance of activated sludge according to an embodiment of the present application;

[0021] Figure 2 This is a schematic structural diagram of an in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to an embodiment of the present application;

[0022] Figure 3 A schematic diagram of the working principle of an in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to an embodiment of the present application;

[0023] Figure 4This is a schematic diagram of the structure of a sewage treatment system according to an embodiment of the present application;

[0024] Figure 5 A schematic structural diagram of a sewage treatment system according to another embodiment of the present application;

[0025] Figure 6 This is a structural schematic diagram of a sewage treatment system according to another embodiment of the present application;

[0026] Figure 7 A comparison chart of the MLVSS / MLSS values ​​of activated sludge at the feed inlet and different discharge outlets of the in-situ expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to an embodiment of the present application;

[0027] Figure 8 A comparison chart of the absolute abundance of ammonia oxidizing bacteria and nitrite oxidizing bacteria in activated sludge at the feed inlet and different discharge outlets of an in-situ expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to an embodiment of the present application;

[0028] Fig. 9 It is a comparison chart of experimental results of the sewage treatment system of the embodiment of the present application and the sewage treatment system of the prior art.

[0029] Reference numerals:

[0030] 100-first stage separation unit, 200-second stage separation unit;

[0031] 1-outer cylinder, 11-partition wall, 111-communication hole, 12-first separation chamber, 13-second separation chamber, 14-first feed port, 15-first underflow port, 16-first overflow port, 17-second feed port, 18-second underflow port, 19-second overflow port, 110-discharge port;

[0032] 2-first inner cone, 21-first conical section, 22-first cylindrical section;

[0033] 3-second inner cone, 31-second conical section, 32-second cylindrical section;

[0034] 4-helical body, 41-columnar portion, 411-connecting cavity, 42-spiral blades, 43-spiral flow channel;

[0035] 5-biochemical treatment unit, 51-anaerobic zone, 52-first anoxic zone, 53-first aerobic zone, 54-second anoxic zone, 55-second aerobic zone, 56-membrane module;

[0036] 6-second sedimentation tank, 71-first internal return pipeline, 72-second internal return pipeline, 73-external return pipeline, 8-primary sedimentation tank. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present application more clear, the embodiments of the present application will be described in detail below. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0038] The present application is further described in detail below in conjunction with specific examples, but the examples should not be construed as limiting the present application.

[0039] like Figure 1 As shown, the embodiment of the present application provides a method for improving the biochemical treatment performance of activated sludge, comprising the following steps:

[0040] S102: Inputting activated sludge from a first feed port of the first separation unit into a first separation chamber of the first separation unit, so that the organic matter and the inorganic matter in the activated sludge are separated by spiral motion of the activated sludge in the first separation chamber, so that the concentration of inorganic matter in the sludge discharged from a first underflow port of the first separation unit is increased and the concentration of organic matter is decreased, and the concentration of inorganic matter in the activated sludge discharged from a first overflow port of the first separation unit is decreased and the concentration of organic matter is increased;

[0041] S104: The activated sludge discharged from the first overflow port of the first separation unit is input into the second separation chamber of the second separation unit through the second feed port of the second separation unit, so as to recover the activated sludge enriched with nitrifying bacteria from the second underflow port of the second separation unit through the spiral movement of the activated sludge in the second separation chamber.

[0042] The method for improving the biochemical treatment performance of activated sludge in the embodiment of the present application can be adopted Figure 2 The in-situ expansion device of the sewage treatment system for improving the biochemical treatment performance of activated sludge is realized as shown. In the process of improving the biochemical treatment performance of activated sludge, first, the activated sludge to be treated can be input into the first-stage separation unit 100, and the activated sludge is spirally moved in the first separation chamber 12 of the first-stage separation unit 100 to separate the organic matter and the inorganic matter in the activated sludge, so that compared with the activated sludge entering the first-stage separation unit 100 from the first feed inlet 14, the concentration of inorganic matter in the sludge discharged from the first underflow outlet 15 of the first-stage separation unit 100 is increased and the concentration of organic matter is reduced, while the concentration of inorganic matter in the sludge discharged from the first underflow outlet 15 of the first-stage separation unit 100 is increased and the concentration of organic matter is reduced. The concentration of inorganic matter in the activated sludge discharged from the first overflow port 16 of the unit 100 is reduced and the concentration of organic matter is increased; then, the activated sludge discharged from the first overflow port 16 of the first-stage separation unit 100 can be input into the second-stage separation unit 200, and the activated sludge can perform spiral motion in the second separation chamber 13 of the second-stage separation unit 200, so that the second-stage separation unit 200 can enrich nitrifying bacteria to increase the abundance of nitrifying bacteria in the activated sludge discharged from the second underflow port 18 of the second-stage separation unit 200.

[0043] After the activated sludge is treated by the two-stage separation units (the first-stage separation unit 100 and the second-stage separation unit 200), the activated sludge discharged from the second underflow port 18 of the second-stage separation unit 200 is transported to the biochemical treatment unit 5 of the sewage treatment system for sewage treatment; the sludge discharged from the first underflow port 15 of the first-stage separation unit 100 and the second overflow port 19 of the second-stage separation unit 200 is transported to the sludge thickening tank of the sewage treatment system to reduce the volume of the sludge, thereby reducing the subsequent treatment cost of the sludge and the impact on the environment.

[0044] In the method for improving the biochemical treatment performance of activated sludge, the first-stage separation unit 100 is used to remove inorganic particulate matter in the activated sludge to reduce the concentration of inorganic particulate matter in the activated sludge and improve the MLVSS in the activated sludge; the second-stage separation unit 200 is used to recover and enrich nitrifying bacteria in the activated sludge to increase the proportion of microorganisms in a unit volume of activated sludge, thereby effectively improving the purification function of the biochemical treatment unit 5.

[0045] In some exemplary embodiments, the pressure of the activated sludge input into the first feed port 14 of the first-stage separation unit 100 is 0.2 MPa to 0.5 MPa.

[0046] In some exemplary embodiments, the concentration of the activated sludge input into the first feed port 14 of the first-stage separation unit 100 is in a range of 2.0 g / L to 50.0 g / L.

[0047] By coordinating the pressure and concentration range of the activated sludge input into the first-stage separation unit 100, the two-stage separation unit can be used to achieve efficient and effective treatment of the activated sludge, so as to improve the biochemical treatment performance of the activated sludge after treatment by the two-stage separation unit.

[0048] Of course, the pressure and concentration range of the activated sludge input into the first-stage separation unit 100 are not limited to the above ranges, and can also be adjusted according to actual needs.

[0049] like Figure 2-Figure 3 As shown, the embodiment of the present application also provides an in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge, including: a first-stage separation unit 100 and a second-stage separation unit 200.

[0050] The first-stage separation unit 100 has a first separation chamber 12, and a first feed port 14, a first underflow port 15 and a first overflow port 16 connected to the first separation chamber 12. The first-stage separation unit 100 is configured to separate organic matter from inorganic matter in the activated sludge through the spiral movement of the activated sludge input into the first separation chamber 12 from the first feed port 14, so that the concentration of inorganic matter in the activated sludge discharged from the first overflow port 16 is reduced and the concentration of organic matter is increased.

[0051] The second-stage separation unit 200 has a second separation chamber 13, and a second feed port 17, a second underflow port 18 and a second overflow port 19 connected to the second separation chamber 13, and the first overflow port 16 is connected to the second feed port 17. The second-stage separation unit 200 is configured to recover the activated sludge enriched with nitrifying bacteria from the second underflow port 18 through the spiral movement of the activated sludge input into the second separation chamber 13 from the second feed port 17.

[0052] In the in-situ expansion device for the sewage treatment system, the first overflow port 16 of the first-stage separation unit 100 is connected to the second feed port 17 of the second-stage separation unit 200, so that the first-stage separation unit 100 and the second-stage separation unit 200 are connected in series.

[0053] When the in-situ expansion device of the sewage treatment system is working, the activated sludge to be treated can be input into the first separation chamber 12 of the first-stage separation unit 100 from the first feed port 14, and can perform spiral motion in the first separation chamber 12 to separate the organic matter and inorganic matter in the activated sludge, so that compared with the activated sludge entering from the first feed port 14, the concentration of inorganic matter in the sludge discharged from the first underflow port 15 is increased and the concentration of organic matter is decreased, while the concentration of inorganic matter in the activated sludge discharged from the first overflow port 16 is decreased and the concentration of organic matter is increased.

[0054] The activated sludge discharged from the first overflow port 16 can be input into the second separation chamber 13 of the second separation unit 200 from the second feed port 17 and can perform spiral motion in the second separation chamber 13 to increase the abundance of nitrifying bacteria in the activated sludge discharged from the second underflow port 18 of the second separation unit 200.

[0055] By means of the in-situ expansion device of the sewage treatment system, the MLVSS in the activated sludge can be increased, thereby increasing the proportion of microorganisms per unit volume, so as to effectively improve the sewage purification function of the biochemical treatment unit 5 of the sewage treatment system.

[0056] In some exemplary embodiments, Figure 2 and Figure 3 As shown, the in-situ expansion device for the sewage treatment system also includes an outer cylinder 1, a first inner cone 2 and a second inner cone 3.

[0057] A partition wall 11 is provided inside the outer cylinder 1 to separate the space inside the outer cylinder 1 into a first separation chamber 12 and a second separation chamber 13. The outer cylinder 1 may be a cylindrical cylinder. Of course, the outer cylinder 1 may also be a non-cylindrical cylinder.

[0058] The first inner cone 2 is disposed in the first separation chamber 12 , with the small end of the first inner cone 2 facing the side where the first feed port 14 and the first overflow port 16 are located, and the first underflow port 15 is close to the large end of the first inner cone 2 .

[0059] The second inner cone 3 is disposed in the second separation chamber 13 , with the small end of the second inner cone 3 facing the side where the second feed port 17 and the second overflow port 19 are located, and the second underflow port 18 is close to the large end of the second inner cone 3 .

[0060] The activated sludge enters the first separation chamber 12 from the first feed port 14 and performs spiral motion. The activated sludge rotates in the first separation chamber 12 to generate a spiral flow. Under the action of the first inner cone 2, the spiral flow is divided into two parts. One part of the spiral flow (such as Figure 3 The outer spiral flow (shown as M1 in FIG. 1 ) moves toward the first bottom flow port 15 and is discharged from the first bottom flow port 15. The other part of the spiral flow (shown as M1 in FIG. 1 ) moves toward the first bottom flow port 15 and is discharged from the first bottom flow port 15. Figure 3 In the first separation chamber 12, there are both an outer spiral flow M1 moving downward and an inner spiral flow M2 moving upward. In the first separation chamber 12, the basic principle of separation of inorganic particles and organic particles is centrifugal sedimentation. Due to the large centrifugal force, inorganic particles move toward the inner wall of the outer cylinder 1 and are discharged from the first bottom flow port 15 along with the outer spiral flow M1; organic particles are discharged from the first overflow port 16 along with the inner spiral flow M2 before they can settle due to the small centrifugal force, thereby separating the organic matter from the inorganic matter in the activated sludge.

[0061] The activated sludge discharged from the first overflow port 16 enters the second separation chamber 13 through the second feed port 17 and performs spiral motion. The activated sludge rotates in the second separation chamber 13 to generate a spiral flow. Under the action of the second inner cone 3, the spiral flow is divided into two parts. One part of the spiral flow (such as Figure 3 The outer spiral flow (shown as M3 in FIG. 1 ) moves toward the second bottom flow port 18 and is discharged from the second bottom flow port 18, and the other part of the spiral flow (shown as M3 in FIG. 1 ) moves toward the second bottom flow port 18 and is discharged from the second bottom flow port 18. Figure 3 The inner spiral flow (inner spiral flow shown in M4) moves to the second overflow port 19 and is discharged from the second overflow port 19. Since the density of nitrifying bacteria in the activated sludge is higher than the density of conventional heterotrophic microorganisms, the activated sludge discharged from the second underflow port 18 is enriched with nitrifying bacteria.

[0062] In some exemplary embodiments, Figure 2As shown, the small heads of the first inner cone 2 and the second inner cone 3 are both facing the partition wall 11, the first feed port 14, the first bottom flow port 15 and the second bottom flow port 18 are all arranged on the side wall of the outer cylinder 1, and the first feed port 14 and the first overflow port 16 are located on the side of the first separation chamber 12 close to the partition wall 11, the first bottom flow port 15 is located on the side of the first separation chamber 12 away from the partition wall 11, the second feed port 17 is arranged on the side of the second separation chamber 13 close to the partition wall 11, and the partition wall 11 is provided with a connecting hole 111 connecting the first overflow port 16 and the second feed port 17.

[0063] The small ends of the first inner cone 2 and the second inner cone 3 are both facing the partition wall 11, so that the first inner cone 2 and the second inner cone 3 can be arranged basically symmetrically. The first feed port 14 can be located in the middle of the outer cylinder 1; the first underflow port 15 can be located at the lower part of the outer cylinder 1, the first underflow port 15 and the second overflow port 19 can be connected to the sludge thickening tank of the sewage treatment system, and the second underflow port 18 can be located above the outer cylinder 1 and can be connected to the biochemical treatment unit 5 of the sewage treatment system.

[0064] The in-situ expansion device for the sewage treatment system has a simple and compact structure, a small volume and a low cost.

[0065] In some exemplary embodiments, Figure 2 As shown, the first inner cone 2 includes a first conical section 21 and a first cylindrical section 22, one end of the first cylindrical section 22 is connected to the large end of the first conical section 21, and the other end of the first cylindrical section 22 is connected to one end wall of the outer cylinder 1; the second inner cone 3 includes a second conical section 31 and a second cylindrical section 32, one end of the second cylindrical section 32 is connected to the large end of the second conical section 31, and the other end of the second cylindrical section 32 is connected to the other end wall of the outer cylinder 1. Among them, the first conical section 21 and the second conical section 31 can be conical, and the first cylindrical section 22 and the second cylindrical section 32 can be cylindrical.

[0066] In some exemplary embodiments, Figure 2 As shown, the in-situ expansion device of the sewage treatment system also includes a spiral body 4, which is arranged in the second separation chamber 13 and close to the partition wall 11. The spiral body 4 includes a cylindrical portion 41 and a spiral blade 42. The spiral blade 42 is arranged between the outer wall surface of the cylindrical portion 41 and the inner wall surface of the outer cylinder 1 to form a spiral flow channel 43. The second feed port 17 is connected to the inlet of the spiral flow channel 43, and the outlet of the spiral flow channel 43 is close to the small head end of the second inner cone 3.

[0067] A spiral body 4 is provided in the second separation chamber 13, and an annular cavity is provided between the cylindrical portion 41 of the spiral body 4 and the inner wall of the outer cylinder 1. The annular cavity is divided into a spiral flow channel 43 by spiral blades 42, and the inlet of the spiral flow channel 43 is connected to the second feed port 17, and the outlet of the spiral flow channel 43 is close to the small head end of the second inner cone 3, so that the activated sludge entering from the second feed port 17 first enters the spiral flow channel 43 to perform a spiral motion, so that the activated sludge can realize the enrichment of nitrifying bacteria in the second separation chamber 13, and the activated sludge enriched with nitrifying bacteria can be recovered through the second bottom flow port 18.

[0068] In some exemplary embodiments, Figure 2 As shown, a connecting cavity 411 is provided in the cylindrical portion 41 of the spiral body 4, a discharge port 110 is provided on the side wall of the outer cylinder 1, and the second overflow port 19 is provided in the cylindrical portion 41 and communicates with the discharge port 110 through the connecting cavity 411. The discharge port 110 may be located on the opposite side of the first feed port 14.

[0069] A connecting cavity 411 is provided in the cylindrical portion 41 of the spiral body 4, and the second overflow port 19 can be connected with the discharge port 110 on the side wall of the outer cylinder 1 through the connecting cavity 411, so that the sludge overflowing from the second overflow port 19 can be discharged from the discharge port 110 after passing through the connecting cavity 411.

[0070] In some exemplary embodiments, Figure 2 As shown, the size of the in-situ expansion device of the sewage treatment system meets at least one of the following requirements:

[0071] The inner diameter D of the outer cylinder 1 is: 50mm≤D≤250mm;

[0072] The distance L between the partition wall 11 and the large end of the first tapered section 21 is 1 3.0D≤L 1 ≤6.0D, the distance L between the partition wall 11 and the large end of the second tapered section 31 2 3.0D≤L 2 ≤6.0D;

[0073] The diameter d of the first feed port 14 is: d≤0.25D;

[0074] Diameter U of the first bottom flow port 15 1 For: U 1 ≤0.15D, diameter U of the second underflow port 18 2 For: U 2 ≤0.15D;

[0075] The diameter O of the first overflow port 16 1 For: 1 ≤0.25D, diameter O of the second overflow port 192 For: 2 ≤0.25D;

[0076] The diameter F of the discharge port 110 is: F ≥ O 2 ;

[0077] One end of the first overflow port 16 extends into the first separation chamber 12, and the length l of the first overflow port 16 extending into the first separation chamber 12 1 =0.4D≤l 1 ≤0.8D, one end of the second overflow port 19 extends into the second separation chamber 13, and the length l extending into the second separation chamber 13 2 =0.4D≤l 2 ≤0.8D;

[0078] The outer diameter N of the cylindrical portion 41 is: N≤0.80D;

[0079] The number of turns of the spiral blade 42 is: 2-6;

[0080] The helical angle β of the helical blade 42 is: 0°≤β≤30°;

[0081] The diameter D of the large end of the first tapered section 21 1 For: D 1 ≤0.80D, the diameter D of the large end of the second tapered section 31 2 For: D 2 ≤0.80D;

[0082] The height h of the first tapered section 21 1 =2.0D≤h 1 ≤3.5D, height h of the second tapered section 31 2 =2.0D≤h 2 ≤3.5D;

[0083] The cone angle θ of the first cone section 21 1 =16°≤θ 1 ≤24°, the cone angle θ of the second cone section 31 2 =16°≤θ 2 ≤24°;

[0084] The height G of the first cylindrical section 22 1 =0.5D 1 ≤G 1 ≤1.5D 1 , the height G of the second cylindrical section 32 2 =0.5D 2 ≤G 2 ≤1.5D 2 .

[0085] Of course, the dimensions of the in-situ expansion device of the sewage treatment system are not limited to the above ranges and can be adjusted according to actual needs.

[0086] It should be understood that the above-mentioned "diameter" may refer to the diameter when the components, structures, etc. are cylindrical or circular, or may refer to the equivalent diameter when the components, structures, etc. are non-cylindrical or non-circular.

[0087] In a specific embodiment, the inner diameter D of the outer cylinder 1 is 80 mm; the diameter d of the first feed port 14 is 20 mm; the diameter D of the large end of the first conical section 21 is 1 The diameter D of the large end of the second tapered section 31 is 64 mm. 2 The diameter of the first overflow port 16 is 60 mm; 1 is 16 mm, and the diameter O of the second overflow port 19 is 2 The overflow discharge port 110 has a diameter F of 20 mm; the diameter U of the first bottom flow port 15 is 1 is 8 mm, and the diameter U of the second bottom flow port 18 is 2 The length of the first overflow port 16 extending into the first separation chamber 12 is l 1 The length l of the second overflow port 19 extending into the second separation chamber 13 is 55 mm. 2 35mm; the length L of the first separation chamber 12 1 is 320 mm, and the length L of the second separation chamber 13 is 2 The height h of the first conical section 21 is 250 mm; 1 is 230 mm, and the height h of the second tapered section 31 is 2 The cone angle θ of the first conical section 21 is 170 mm; 1 is 16°, and the cone angle θ of the second cone section 31 is 2 The number of turns of the spiral blade 42 is 4; the spiral angle β of the spiral blade 42 is 10°; the outer diameter N of the cylindrical portion 41 is 64 mm; the height G of the first cylindrical section 22 1 is 40 mm, and the height G of the second cylindrical section 32 is 2 It is 35mm.

[0088] In some exemplary embodiments, the first feed port 14 is arranged tangentially to the first separation chamber 12 so that the activated sludge forms a spiral motion in the first separation chamber 12 to achieve separation of organic matter and inorganic matter.

[0089] Of course, the first feed port 14 and the first separation chamber 12 may also be arranged to be non-tangential, and the spiral movement of the activated sludge in the first separation chamber 12 is achieved by arranging a spiral flow channel in the first separation chamber 12 (such as: similar to the spiral flow channel 43 in the second separation chamber 13).

[0090] In some exemplary embodiments, the in-situ expansion device for the sewage treatment system further includes a delivery pump (not shown), the outlet of the delivery pump is connected to the first feed port 14, and the delivery pump is configured so that the pressure of the activated sludge input into the first feed port 14 is 0.2 MPa to 0.5 MPa. The delivery pump device for applying working pressure to the activated sludge can be a mechanical device for conveying fluids, such as a submersible pump and a rotor pump.

[0091] In a specific embodiment, the sewage treatment system in-situ expansion device is applied to Figure 4 The sewage treatment system shown adopts the anaerobic-anoxic-aerobic activated sludge method and is arranged in the first internal return pipe 71. The conveying pump device can use a rotor pump. The pressure of the activated sludge input to the first feed port 14 can be 0.3MPa, and the concentration of the activated sludge input to the first feed port 14 can be 3.2g / L.

[0092] In some exemplary embodiments, the first underflow port 15, the second underflow port 15 and the discharge port 110 are all equipped with electric valves to adjust the sludge discharge flow rate.

[0093] In some exemplary embodiments, the material of the sewage treatment system in-situ expansion device is cast iron or stainless steel. Of course, according to actual conditions, the sewage treatment system in-situ expansion device can also be made of other materials.

[0094] In some exemplary embodiments, the axis of the outer cylinder 1 is perpendicular to the horizontal plane, and the first separation chamber 12 is located below the second separation chamber 13, so as to realize the normal installation of the in-situ expansion device of the sewage treatment system. Figure 2 and Figure 3 As shown; or, the axis of the outer cylinder 1 is inclined relative to the horizontal plane to achieve oblique installation of the in-situ expansion device of the sewage treatment system; or, the axis of the outer cylinder 1 is parallel to the horizontal plane to achieve flat installation of the in-situ expansion device of the sewage treatment system.

[0095] An embodiment of the present application also provides a sewage treatment system, comprising an in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to any of the above embodiments.

[0096] The in-situ expansion device of the sewage treatment system has a good effect on the removal of inorganic particulate matter in the activated sludge and the recovery and enrichment of nitrifying bacteria. It can effectively increase the treatment load of the sewage treatment system and realize the in-situ efficiency enhancement and expansion of the sewage treatment system.

[0097] In some exemplary embodiments, Figure 4As shown, the sewage treatment system is a system adopting an anaerobic-anoxic-aerobic activated sludge method, and also includes a primary sedimentation tank 8, a biochemical treatment unit 5 and a secondary sedimentation tank 6. The primary sedimentation tank 8, the biochemical treatment unit 5 and the secondary sedimentation tank 6 are connected in sequence. The biochemical treatment unit 5 is provided with an anaerobic zone 51, a first anoxic zone 52 and a first aerobic zone 53 in sequence. A first internal return pipeline 71 is provided between the first aerobic zone 53 and the first anoxic zone 52. An external return pipeline 73 is provided between the secondary sedimentation tank 6 and the anaerobic zone 51. The in-situ expansion device of the sewage treatment system is provided in at least one of the external return pipeline 73 and the first internal return pipeline 71. When the in-situ expansion device of the sewage treatment system is arranged in the external return pipeline 73, the first feed port 14 and the second underflow port 18 of the in-situ expansion device of the sewage treatment system are both connected to the external return pipeline 73; when the in-situ expansion device of the sewage treatment system is arranged in the first internal return pipeline 71, the first feed port 14 and the second underflow port 18 of the in-situ expansion device of the sewage treatment system are both connected to the first internal return pipeline 71.

[0098] In some other exemplary embodiments, Figure 5 As shown, the sewage treatment system is a system using a membrane bioreactor method, and also includes a primary sedimentation tank 8 and a biochemical treatment unit 5. The primary sedimentation tank 8 and the biochemical treatment unit 5 are connected. The biochemical treatment unit 5 includes a membrane bioreactor. A first anoxic zone 52 and a first aerobic zone 53 are sequentially arranged in the membrane bioreactor. A membrane assembly 56 is arranged in the first aerobic zone 53. A first internal reflux pipeline 71 is arranged between the first aerobic zone 53 and the first anoxic zone 52. The in-situ expansion device of the sewage treatment system is arranged in the first internal reflux pipeline 71, that is, the first feed port 14 and the second underflow port 18 of the in-situ expansion device of the sewage treatment system are both connected to the first internal reflux pipeline 71.

[0099] In some other exemplary embodiments, Figure 6As shown, the sewage treatment system is a system adopting a two-stage anoxic-aerobic activated sludge method, and also includes a primary sedimentation tank 8, a biochemical treatment unit 5 and a secondary sedimentation tank 6. The primary sedimentation tank 8, the biochemical treatment unit 5 and the secondary sedimentation tank 6 are connected in sequence. The biochemical treatment unit 5 is provided with a first anoxic zone 52, a first aerobic zone 53, a second anoxic zone 54 and a second aerobic zone 55 in sequence. A first internal return pipeline 71 is provided between the first aerobic zone 53 and the first anoxic zone 52, a second internal return pipeline 72 is provided between the second aerobic zone 55 and the second anoxic zone 54, an external return pipeline 73 is provided between the secondary sedimentation tank 6 and the first anoxic zone 52, and an in-situ expansion device of the sewage treatment system is provided in at least one of the external return pipeline 73, the first internal return pipeline 71 and the second internal return pipeline 72. When the in-situ expansion device of the sewage treatment system is arranged in the external return pipeline 73, the first feed port 14 and the second underflow port 18 of the in-situ expansion device of the sewage treatment system are both connected to the external return pipeline 73; when the in-situ expansion device of the sewage treatment system is arranged in the first internal return pipeline 71, the first feed port 14 and the second underflow port 18 of the in-situ expansion device of the sewage treatment system are both connected to the first internal return pipeline 71; when the in-situ expansion device of the sewage treatment system is arranged in the second internal return pipeline 72, the first feed port 14 and the second underflow port 18 of the in-situ expansion device of the sewage treatment system are both connected to the second internal return pipeline 72.

[0100] In some other exemplary embodiments, the sewage treatment system is a system that adopts a sequencing batch activated sludge process (not shown). The system integrates functions such as homogenization, biodegradation, and sedimentation in one pool, has no sludge return system, and is divided into five stages in time sequence: water inlet, aeration, sedimentation, drainage, and standby. The in-situ expansion device of the sewage treatment system is arranged in the sludge discharge pipeline of the system, that is, the first feed port 14 of the in-situ expansion device of the sewage treatment system is connected to the sludge discharge pipeline of the system, and the sludge of the second underflow port 18 is discharged back to the sewage treatment system.

[0101] The in-situ expansion device of the sewage treatment system of the embodiment of the present application can be used in systems utilizing biochemical treatment processes such as the anaerobic-anoxic-aerobic activated sludge process, the two-stage anoxic-aerobic activated sludge process, the membrane bioreactor process, and the sequencing batch activated sludge process.

[0102] The activated sludge is treated by the in-situ expansion device of the sewage treatment system. The changes of MLVSS / MLSS in the sludge are as follows: Figure 7 As shown in Figure 2, the abundance of ammonia oxidizing bacteria and nitrite oxidizing bacteria in sludge changes as shown in Figure 2. Figure 8 It should be noted that Figure 7-Figure 9 In the figure, “feed port” refers to the first feed port 14 , “discharge port I” refers to the first underflow port 15 and the discharge port 110 , and “discharge port II” refers to the second underflow port 18 .

[0103] Depend on Figure 7 and Figure 8It can be seen that compared with the sludge at the feed port, the MLVSS / MLSS in the sludge at the discharge port I decreased by about 18.6%, and the MLVSS / MLSS in the sludge at the discharge port II increased by about 5.6%; the absolute abundance of ammonia oxidizing bacteria in the sludge at the discharge port I decreased by about 13.6%, and the absolute abundance of ammonia oxidizing bacteria in the sludge at the discharge port II increased by about 17.9%; the absolute abundance of nitrite oxidizing bacteria in the sludge at the discharge port I decreased by about 8.5%, and the absolute abundance of nitrite oxidizing bacteria in the sludge at the discharge port II increased by about 27.5%.

[0104] In terms of pollutant removal, the sewage treatment system in-situ expansion device enhances the treatment efficiency of the biochemical treatment unit 5, wherein the COD (Chemical Oxygen Demand) removal rate can be increased by about 5.4%, the ammonia nitrogen removal rate can be increased by about 9.6%, and the aeration energy consumption can be reduced by about 15.2%. In addition, under the premise of ensuring that other operating parameters remain unchanged, the sewage inflow of the sewage treatment system increases by 15%, and the effluent of the biochemical treatment unit 5 can still meet the standard of qualified discharge.

[0105] The properties of sludge produced by different biochemical processes in sewage treatment systems are also different. Fig. 9 The results show the effect of removing inorganic matter (such as inorganic sand, etc.) and enriching nitrifying bacteria in the sludge of the sewage treatment system in sludge treatment system using different types of activated sludge methods by the in-situ expansion device of the sewage treatment system of the present application. Fig. 9It can be seen that for the sewage treatment system using the anaerobic-anoxic-aerobic activated sludge method, compared with the sludge at the feed inlet of the in-situ expansion device of the sewage treatment system, the absolute abundance of MLVSS / MLSS, ammonia oxidizing bacteria and nitrite oxidizing bacteria in the sludge returned to the biochemical treatment unit 5 from the discharge port II increased by approximately 4.0%, 9.4% and 11.4%, respectively; for the sewage treatment system using the two-stage anoxic-aerobic activated sludge method, compared with the sludge at the feed inlet of the in-situ expansion device of the sewage treatment system, the absolute abundance of MLVSS / MLSS, ammonia oxidizing bacteria and nitrite oxidizing bacteria in the sludge returned to the biochemical treatment unit 5 from the discharge port II increased by approximately 3.8%, 9.3%, respectively. and 10.5%; for the sewage treatment system using the membrane bioreactor method, compared with the sludge at the feed inlet of the sewage treatment system in-situ expansion device, the MLVSS / MLSS, ammonia oxidizing bacteria and nitrite oxidizing bacteria in the sludge returned from the discharge port II to the biochemical treatment unit 5 increased by about 3.3%, 9.9% and 11.3% respectively; for the sewage treatment system using the sequencing batch activated sludge method, compared with the sludge at the feed inlet of the sewage treatment system in-situ expansion device, the MLVSS / MLSS, ammonia oxidizing bacteria and nitrite oxidizing bacteria in the sludge returned from the discharge port II to the biochemical treatment unit 5 increased by about 3.7%, 8.4% and 10.6% respectively. The results show that the sewage treatment system in-situ expansion device for improving the biochemical treatment performance of activated sludge provided in the embodiment of the present application can achieve the removal of inorganic sand and the enrichment of nitrifying bacteria in the activated sludge, and has a certain universality.

[0106] In some exemplary embodiments, a plurality of in-situ expansion devices for the sewage treatment system are provided, and the plurality of in-situ expansion devices for the sewage treatment system are connected in parallel.

[0107] According to the processing capacity of activated sludge, multiple in-situ expansion devices of the sewage treatment system can be operated in parallel to increase the processing capacity of activated sludge, thereby improving the sewage treatment performance of the sewage treatment system.

[0108] In some exemplary embodiments, the operation time and frequency of the in-situ expansion device of the sewage treatment system can be linked and adjusted according to the parameters of the sludge age of the biochemical process of the sewage treatment system.

[0109] In some exemplary embodiments, the sewage treatment system also includes a sludge thickening tank (not shown), and the first underflow port 15 and the second overflow port 19 (or the discharge port 110) of the in-situ expansion device of the sewage treatment system are both connected to the sludge thickening tank to transport the sludge discharged from the first underflow port 15 of the first-stage separation unit 100 and the second overflow port 19 (or the discharge port 110) of the second-stage separation unit 200 to the sludge thickening tank of the sewage treatment system.

[0110] In the description of the present application, it should be understood that the terms "length", "up", "down", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0111] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0112] In the description of the present application, “plurality” means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0113] In this application, unless otherwise clearly specified and limited, the term "connection" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0114] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0115] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0116] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for improving the biochemical treatment performance of activated sludge, characterized in that: include: Inputting activated sludge from a first feed port of a first-stage separation unit into a first separation chamber of the first-stage separation unit, so that the organic matter and the inorganic matter in the activated sludge are separated by spiral motion of the activated sludge in the first separation chamber, so that the concentration of inorganic matter in the sludge discharged from a first underflow port of the first-stage separation unit is increased and the concentration of organic matter is decreased, and the concentration of inorganic matter in the activated sludge discharged from a first overflow port of the first-stage separation unit is decreased and the concentration of organic matter is increased; The activated sludge discharged from the first overflow port of the first-stage separation unit is input into the second separation chamber of the second-stage separation unit from the second feed port of the second-stage separation unit, so that the activated sludge enriched with nitrifying bacteria can be recovered from the second underflow port of the second-stage separation unit through the spiral movement of the activated sludge in the second separation chamber.

2. The method for improving the biochemical treatment performance of activated sludge according to claim 1, characterized in that: The pressure of the activated sludge input into the first feed inlet of the first-stage separation unit is 0.2 MPa to 0.5 MPa; and / or The concentration of the activated sludge input into the first feed inlet of the first-stage separation unit ranges from 2.0 g / L to 50.0 g / L.

3. The method for improving the biochemical treatment performance of activated sludge according to claim 1 or 2, characterized in that: Also includes: The sludge discharged from the first underflow outlet of the first-stage separation unit and the second overflow outlet of the second-stage separation unit is transported to the sludge thickening tank of the sewage treatment system, and the activated sludge discharged from the second underflow outlet of the second-stage separation unit is transported to the biochemical treatment unit of the sewage treatment system.

4. An in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge, characterized in that: include: A first-stage separation unit comprises a first separation chamber, a first feed port, a first underflow port and a first overflow port connected to the first separation chamber, wherein the first-stage separation unit is configured to separate organic matter from inorganic matter in the activated sludge by spiral motion of the activated sludge input into the first separation chamber from the first feed port, so that the concentration of inorganic matter in the activated sludge discharged from the first overflow port is reduced and the concentration of organic matter is increased; and The second-stage separation unit has a second separation chamber, and a second feed port, a second underflow port and a second overflow port connected to the second separation chamber, and the first overflow port is connected to the second feed port. The second-stage separation unit is configured to recover the activated sludge enriched with nitrifying bacteria from the second underflow port through the spiral movement of the activated sludge input into the second separation chamber from the second feed port.

5. The in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to claim 4 is characterized in that: Also includes: An outer cylinder body, wherein a partition wall is provided inside the outer cylinder body to divide the space inside the outer cylinder body into the first separation chamber and the second separation chamber; A first inner cone is disposed in the first separation chamber, with a small end of the first inner cone facing the side where the first feed port and the first overflow port are located, and the first underflow port is close to a large end of the first inner cone; and A second inner cone is disposed in the second separation chamber, with the small end of the second inner cone facing the side where the second feed port and the second overflow port are located, and the second underflow port is close to the large end of the second inner cone; Wherein, the axis of the outer cylinder is perpendicular to the horizontal plane, and the first separation chamber is located below the second separation chamber; or, the axis of the outer cylinder is inclined relative to the horizontal plane; or, the axis of the outer cylinder is parallel to the horizontal plane.

6. The in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to claim 5 is characterized in that: The small heads of the first inner cone and the second inner cone are both facing the partition wall, the first feed port, the first bottom flow port and the second bottom flow port are all arranged on the side wall of the outer cylinder, and the first feed port and the first overflow port are located on the side of the first separation chamber close to the partition wall, the first bottom flow port is located on the side of the first separation chamber away from the partition wall, the second feed port is arranged on the side of the second separation chamber close to the partition wall, and the partition wall is provided with a connecting hole connecting the first overflow port and the second feed port.

7. The in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to claim 5, characterized in that: Also includes: A spiral body is arranged in the second separation chamber and close to the partition wall. The spiral body includes a cylindrical portion and spiral blades. The spiral blades are arranged between the outer wall surface of the cylindrical portion and the inner wall surface of the outer cylinder to form a spiral flow channel. The second feed port is connected to the inlet of the spiral flow channel, and the outlet of the spiral flow channel is close to the small head end of the second inner cone.

8. The in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to claim 7, characterized in that: A communication cavity is provided in the cylindrical portion, a discharge port is provided on the side wall of the outer cylinder, and the second overflow port is provided in the cylindrical portion and communicates with the discharge port through the communication cavity.

9. The in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to claim 8, characterized in that: The first inner cone includes a first conical section and a first cylindrical section, one end of the first cylindrical section is connected to the large end of the first conical section, and the other end of the first cylindrical section is connected to an end wall of the outer cylinder; The second inner cone includes a second conical section and a second cylindrical section, one end of the second cylindrical section is connected to the large end of the second conical section, and the other end of the second cylindrical section is connected to the other end wall of the outer cylinder.

10. The in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to claim 9, characterized in that: The size of the in-situ expansion device of the sewage treatment system meets at least one of the following requirements: The inner diameter D of the outer cylinder is: 50mm≤D≤250mm; The distance L1 between the partition wall and the large end of the first tapered section is: 3.0D≤L1≤6.0D, and the distance L2 between the partition wall and the large end of the second tapered section is: 3.0D≤L2≤6.0D; The diameter d of the first feed port is: d≤0.25D; The diameter U1 of the first underflow port is: U1≤0.15D, and the diameter U2 of the second underflow port is: U2≤0.15D; The diameter O1 of the first overflow port is: O1≤0.25D, and the diameter O2 of the second overflow port is: O2≤0.25D; The diameter F of the discharge port is: F ≥ O2; One end of the first overflow port extends into the first separation chamber, and the length l1 extending into the first separation chamber is: 0.4D≤l1≤0.8D; one end of the second overflow port extends into the second separation chamber, and the length l2 extending into the second separation chamber is: 0.4D≤l2≤0.8D; The outer diameter N of the cylindrical portion is: N≤0.80D; The number of turns of the spiral blade is: 2-6; The helical angle β of the spiral blade is: 0°≤β≤30°; The diameter D1 of the large end of the first tapered section is: D1≤0.80D, and the diameter D2 of the large end of the second tapered section is: D2≤0.80D; The height h1 of the first tapered section is: 2.0D≤h1≤3.5D, and the height h2 of the second tapered section is: 2.0D≤h2≤3.5D; The cone angle θ1 of the first cone section is: 16°≤θ1≤24°, and the cone angle θ2 of the second cone section is: 16°≤θ2≤24°; The height G1 of the first columnar segment is: 0.5D1≤G1≤1.5D1, and the height G2 of the second columnar segment is: 0.5D2≤G2≤1.5D2.

11. A sewage treatment system, characterized in that: An in-situ capacity expansion device for a sewage treatment system for improving the biochemical treatment performance of activated sludge according to any one of claims 4 to 10; There is one in-situ capacity expansion device for the sewage treatment system; or, there are multiple in-situ capacity expansion devices for the sewage treatment system, and the multiple in-situ capacity expansion devices for the sewage treatment system are connected in parallel.

12. The sewage treatment system according to claim 11, characterized in that: The sewage treatment system is a system using an anaerobic-anoxic-aerobic activated sludge process, and further comprises a biochemical treatment unit and a secondary sedimentation tank, wherein an anaerobic zone, a first anoxic zone and a first aerobic zone are sequentially arranged in the biochemical treatment unit, a first internal return pipeline is arranged between the first aerobic zone and the first anoxic zone, an external return pipeline is arranged between the secondary sedimentation tank and the anaerobic zone, and the sewage treatment system in-situ expansion device is arranged in at least one of the external return pipeline and the first internal return pipeline; or The sewage treatment system is a system using a membrane bioreactor method, and further includes a biochemical treatment unit, the biochemical treatment unit includes a membrane bioreactor, a first anoxic zone and a first aerobic zone are sequentially arranged in the membrane bioreactor, a membrane assembly is arranged in the first aerobic zone, a first internal reflux pipeline is arranged between the first aerobic zone and the first anoxic zone, and the sewage treatment system in-situ expansion device is arranged in the first internal reflux pipeline; or The sewage treatment system is a system adopting a two-stage anoxic-aerobic activated sludge process, and further comprises a biochemical treatment unit and a secondary sedimentation tank, wherein a first anoxic zone, a first aerobic zone, a second anoxic zone and a second aerobic zone are sequentially arranged in the biochemical treatment unit, a first internal return pipeline is arranged between the first aerobic zone and the first anoxic zone, a second internal return pipeline is arranged between the second aerobic zone and the second anoxic zone, an external return pipeline is arranged between the secondary sedimentation tank and the first anoxic zone, and the sewage treatment system in-situ expansion device is arranged in at least one of the external return pipeline, the first internal return pipeline and the second internal return pipeline; or The sewage treatment system is a system that adopts a sequencing batch activated sludge process, which integrates homogenization, biodegradation, and sedimentation functions in one pool. The sewage treatment system in-situ expansion device is arranged in the sludge discharge pipeline of the system.

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