Activated sludge selecting and concentrating device for sewage treatment

Abstract

The invention discloses an activated sludge selecting and concentrating device for sewage treatment, which belongs to the technical field of sludge treatment and comprises a gas dissolving system and a sludge selecting and concentrating machine. The gas dissolving system is used for carrying out gas dissolving on the activated sludge to be treated under high pressure to form gas-dissolved activated sludge; the sludge selecting and concentrating machine is used for decompressing the air-dissolved activated sludge and releasing bubbles; under the stirring action of a stirrer with the adjustable rotating speed, light-phase components in the sludge float out of the liquid level and are discharged from the top through the air flotation action of bubbles and rotational flow generated by stirring, heavy-phase components containing inorganic sludge are discharged from the bottom, and high-quality-phase sludge in the middle layer is collected from the middle and used for refluxing to a biochemical system. According to the invention, the separation of different phases of sludge can be efficiently, accurately and quickly realized, and the high activity of activated sludge is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of sludge treatment, and in particular to an activated sludge selection and concentration device for sewage treatment. Background Art

[0002] The activated sludge method for sewage treatment has been developed for many years. In addition to the traditional activated sludge methods such as A / O denitrification, A / O phosphorus removal, 2 In addition to nitrogen removal and phosphorus removal by / O, there are also oxidation ditches, SBR and related extended processes. No matter how the process evolves, the core is still to treat sewage with activated sludge. The activated sludge method uses artificial enhanced oxygenation to continuously mix and cultivate sewage and various microbial communities to form flocs containing a variety of microorganisms. The biological coagulation, adsorption and oxidation of activated sludge are used to decompose and remove organic pollutants in the water. Then the mud and water are separated through the secondary sedimentation tank, and most of the sludge is returned to the biological reactor, and the excess is discharged as residual sludge from the biochemical system.

[0003] In activated sludge, organic matter accounts for 75%-85% and inorganic matter accounts for 15%-25%. Organic matter is the main useful substance involved in biochemical reactions, while inorganic matter will reduce the activity of activated sludge when it accounts for a certain proportion. Especially for sewage plants with poor sludge settling performance or poor phosphorus removal effect, sometimes flocculants are added to the biochemical system for emergency treatment. Over time, the inorganicization of activated sludge becomes more serious, and the system eventually collapses.

[0004] Traditional sewage treatment plants use a periodic sludge discharge method, using a residual sludge pump for regular discharge to alleviate the problem of activated sludge inorganicization. However, this method discharges organic and inorganic sludge together indiscriminately. While reducing the inorganic sludge, it also discharges the organic sludge that is beneficial to the system. Therefore, it cannot solve the problem of activated sludge inorganicization. At present, an improved method has been developed based on the traditional periodic sludge discharge method, using an activated sludge screening device (the patent with application number 202223209625.8 discloses an activated sludge screening device for sewage treatment). Through the multi-stage series connection of the activated sludge screening device, the internal and external cyclones generated by the separation principle of the hydrocyclone are used to select the light phase sludge and the heavy phase sludge respectively. Although it increases the proportion of inorganic components in the discharged residual sludge to a certain extent compared with the traditional periodic sludge discharge method. However, it still has the following defects:

[0005] 1. Activated sludge is rich in sludge particles of various particle sizes. The particle size and mass change gradient between adjacent particle sizes is small, and the macroscopic distribution law is present. Unless it is operated under ideal operating conditions, in fact, there is a complete transition phase sludge between the heavy phase sludge and the light phase sludge. Therefore, the stratification and boundary of different phases of sludge are not clear when the sludge screening device is screening the sludge;

[0006] 2. Since the sludge particles have a huge surface area, there are interactions such as adsorption, agglomeration, and network filling between the sludge particles. The mutual interference between the sludge particles of different phases is serious, resulting in poor sludge screening effect;

[0007] 3. The sludge screening device screens the sludge based on the cyclone principle, but the cyclone speed cannot be accurately controlled by the hydraulic cyclone. If the speed is too large or too small, on the one hand, the cyclone screening standard cannot be controlled, that is, the desired sludge particles cannot be accurately screened out. On the other hand, the high-quality sludge particles will collide and rub against each other, causing the sludge particles to break into powdery sludge, which destroys the excellent morphology of the sludge.

[0008] 4. If the pretreatment of the biochemical front end is not good, oil, residual scum, etc. will flow into the sludge screening device, and they will be discharged from the light phase outlet first, greatly reducing the activity of the recovered activated sludge;

[0009] 5. Due to the need for multiple series connections, the land occupied and investment required are very huge.

[0010] When any of the above situations occurs, the inorganic proportion of activated sludge cannot be controlled, the activity of the sludge will deteriorate, the biochemical treatment effect will be poor, and over time it may even lead to the collapse of the entire biochemical system.

[0011] Therefore, how to accurately screen out useful activated sludge, maintain the proportion of organic components in the activated sludge that promote biochemical reactions at a higher value, maintain the high activity of the sludge, and ensure economy while ensuring the screening effect is a technical problem that technical personnel in this field currently need to solve. Summary of the invention

[0012] In view of the shortcomings existing in the above problems, the present invention provides an activated sludge selection and concentration device for sewage treatment.

[0013] The invention discloses an activated sludge selection and concentration device for sewage treatment, comprising: a dissolved air system and a sludge selection and concentration machine;

[0014] The gas dissolving system is used to dissolve gas in the activated sludge to be treated under high pressure to form gas-dissolving activated sludge;

[0015] The sludge selection and thickening machine is used to decompress the dissolved air activated sludge and release the bubbles; and under the stirring action of the stirrer with adjustable speed, through the flotation effect of the bubbles and the vortex generated by the stirring, the light phase components in the sludge float to the liquid surface and are discharged from the top, the heavy phase components containing inorganic sludge are discharged from the bottom, and the high-quality phase sludge in the middle layer is collected from the middle for reflow to the biochemical system.

[0016] As a further improvement of the present invention, the dissolved gas pressure of the activated sludge to be treated is 0.3-0.5 MPa.

[0017] As a further improvement of the present invention, the air dissolving system comprises: a sludge pump, an air compressor and an air dissolving tank;

[0018] The sludge pump and the air compressor are both connected to the gas dissolving tank, and a pressure regulating valve is provided on the connecting pipeline between the gas dissolving tank and the sludge selection and thickening machine; the activated sludge to be treated is sucked by the sludge pump and pumped into the gas dissolving tank, and the air compressor provides a gas source with a pressure of 0.7-0.8MPa to enter the gas dissolving tank, and the gas-water mixed pressure in the gas dissolving tank is adjusted to 0.3-0.5MPa by adjusting the pressure regulating valve, and the activated sludge to be treated is dissolved to form dissolved activated sludge.

[0019] As a further improvement of the present invention, the sludge selection and thickening machine comprises: a cyclone thickening body;

[0020] The cyclone concentrator body is composed of an upper straight cylinder section and a lower conical bucket section;

[0021] A stirrer with adjustable speed is installed on the top of the straight cylinder section, and the blades of the stirrer are placed inside the straight cylinder section;

[0022] A mud inlet pipe is arranged at the upper part of the straight tube section, and the mud inlet pipe is connected to the dissolved gas system. A guide tube connected to the mud inlet pipe is arranged in the cyclone concentrator body;

[0023] A heavy phase sludge discharge port is provided at the bottom of the conical bucket section, a light phase sludge collecting weir is provided in the straight cylinder section, the light phase sludge collecting weir is higher than the paddles of the agitator, a light phase sludge discharge port connected to the light phase sludge collecting weir is provided on the straight cylinder section, and a mud outlet for collecting high-quality phase sludge is provided in the middle of the straight cylinder section.

[0024] As a further improvement of the present invention, the stirring shaft of the agitator is located on the axis of the cyclone concentrating body, the guide tube is coaxially arranged with the stirring shaft of the agitator, and the lower discharge port of the guide tube is higher than the upper blades of the agitator.

[0025] As a further improvement of the present invention, a mud scraper is provided in the conical bucket section.

[0026] As a further improvement of the present invention, a sludge discharge valve is provided on the heavy phase sludge discharge port.

[0027] As a further improvement of the present invention, a working bridge is welded on the top of the straight cylinder section, a reserved hole is set at the center of the working bridge, a prefabricated steel plate is welded on the reserved hole, and bolt holes are reserved on the prefabricated steel plate for fixing and installing the agitator.

[0028] As a further improvement of the present invention, a plurality of mud outlet branch pipes are connected in parallel to the feed end of the mud outlet, and the plurality of mud outlet branch pipes are respectively connected to different heights of the straight tube section, and each mud outlet branch pipe is provided with a mud outlet branch pipe valve and a mud outlet sampling valve.

[0029] As a further improvement of the present invention, samples at different heights are taken for testing through the mud sampling valve, and the optimal mud branch pipe is determined based on the test results; then, the mud branch pipe valve on the optimal mud branch pipe is opened and the mud branch pipe valves on the remaining mud branch pipes are closed to collect high-quality sludge.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention can further remove oil, scum and the like remaining in the activated sludge, and can set a precise rotation speed to accurately separate sludge of different phases by utilizing the effect of cyclone, thereby avoiding mutual interference between sludge particles of different phases and solving the problem of sludge accumulation in the cyclone cone bucket; the activity of the returned activated sludge is completely improved, and the cost performance is very high. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of the activated sludge selection and concentration device for sewage treatment disclosed in the present invention;

[0033] Figure 2 for Figure 1 Cross-section diagram of medium sludge selection and thickener;

[0034] Figure 3 for Figure 1 Top plan view of the medium sludge selection and thickener;

[0035] Figure 4 for Figure 3 Schematic diagram of the reserved and embedded parts of the middle working bridge.

[0036] Explanation of symbols:

[0037] A. Dissolved air system; B. Sludge selection and thickener;

[0038] 100, sludge pump; 200, air compressor; 300, dissolved gas tank; 301, pressure regulating valve; 401, sludge inlet pipe; 402, guide tube; 403, agitator; 404, light phase sludge collection weir; 405, light phase sludge discharge port; 406, heavy phase sludge discharge port; 407, sludge outlet; 408, upper layer sludge outlet branch valve; 409, middle layer sludge outlet branch valve; 410 , lower layer mud outlet branch valve; 411, upper layer mud outlet sampling valve; 412, middle layer mud outlet sampling valve; 413, lower layer mud outlet sampling valve; 414, support leg; 415, paddle; 416, mud scraper; 417, working bridge; 418, cyclone thickening body; 419, mud discharge valve; 501, reserved hole; 502, prefabricated steel plate 502, prefabricated steel plate; 503, bolt hole. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0041] The present invention provides an activated sludge selection and concentrating device for sewage treatment, which can be widely applicable to new construction, renovation and upgrading project scenarios, scenarios with poor pretreatment effects, scenarios with frequent sludge swelling, scenarios with serious activated sludge inorganicization, scenarios with the need to improve the treatment efficiency of the biochemical system, scenarios with the need to reduce the investment in the sludge thickening tank, and scenarios with high intensive requirements and tight land use.

[0042] like Figure 1 As shown, the activated sludge selection and concentrating device for sewage treatment of the present invention comprises a dissolving gas system A and a sludge selection and concentrator B. The dissolving gas system A pre-treats the activated sludge to be treated (nitrification liquid containing a large amount of activated sludge), that is, the activated sludge to be treated is dissolved by gas under high pressure (greater than normal pressure) through the dissolving gas system A to form dissolved gas activated sludge; the dissolved gas activated sludge is decompressed and released in the sludge selection and concentrator B, and under the stirring action of the stirrer with adjustable speed, the light phase expanded sludge, oil or scum is floated to the liquid surface through the flotation and cyclone principles, the inorganic heavy phase sludge is discharged from the bottom, and the high-quality phase sludge is collected and refluxed from the middle layer, so that the separation of different phases of sludge is achieved efficiently, accurately and quickly, and the activity of the returned activated sludge is improved.

[0043] Specific:

[0044] The gas dissolving system A of the present invention comprises a sludge pump 100, an air compressor 200 and a gas dissolving tank 300. The sludge pump 100 and the air compressor 200 are connected in series with the gas dissolving tank 300. The activated sludge to be treated (nitrification liquid containing a large amount of activated sludge) is sucked and pumped into the gas dissolving tank 300 by the sludge pump 100. The air compressor 200 provides a gas source with a pressure of 0.7 to 0.8 MPa to enter the gas dissolving tank 300. The gas-water mixture pressure in the gas dissolving tank 300 is adjusted to 0.4 MPa by adjusting the pressure regulating valve 301. The activated sludge to be treated is gasified to form gas-dissolved activated sludge. The gas-dissolved activated sludge (gas-water mixture) after gas dissolution is sent to the sludge selection and concentrator B through a connecting pipeline. Furthermore, a manhole and an air vent are sequentially provided on the left side wall of the dissolved gas tank 300 from top to bottom, a first sight glass, a second sight glass and a liquid level meter are sequentially provided on the right side wall of the dissolved gas tank 300 from top to bottom, and an emptying valve is provided at the bottom of the dissolved gas tank 300.

[0045] Further references Figure 2 The sludge selection and thickening machine B of the present invention comprises a cyclone thickening machine body 418 and a speed-adjustable agitator 403 arranged at the axis of the cyclone thickening machine body 418. The cyclone thickening machine body 418 is composed of an upper straight cylinder section and a lower conical bucket section. The agitator 403 is composed of a motor, a stirring shaft and a paddle 415 arranged on the stirring shaft. The motor can drive the paddle 415 to rotate at different speeds through the stirring shaft; a mud inlet pipe 401 is arranged on the upper part of the cyclone thickening machine body 418, and a guide tube 402 connected to the mud inlet pipe 401 is arranged in the cyclone thickening machine body 418. Preferably, the mud inlet pipe 401 crosses the side wall of the cyclone thickening machine body 418 and is vertically connected to the guide tube 402. Preferably, the guide tube 402 is coaxially arranged with the stirring shaft of the agitator 403, and the lower discharge port of the guide tube 402 is higher than the paddle 415 of the agitator 403; after The activated sludge after high-pressure aeration flows into the guide tube 402 through the mud inlet pipe 401, and is guided to the middle and lower part of the straight section of the cyclone thickening body 418 and enters the cyclone thickening body 418. A large number of extremely tiny bubbles are released under low pressure conditions to improve the density gradient between different phases of the activated sludge. Driven by the agitator 403, the blades 415 stir the mud and water in the cyclone thickening body 418, and the mud and water are cyclone-stratified in the conical bucket section at the lower part of the cyclone thickening body 418, so that the heavy phase sludge with mostly inorganic components is discharged from the system from the bottom heavy phase sludge discharge port 406, and the light phase sludge with mostly oil, scum and expanded sludge components is collected to the light phase sludge collecting weir 404 and then discharged from the system through the light phase sludge discharge port 405. The high-quality activated sludge is collected by the mud outlet 407 set in the middle of the body for return to the biochemical system.

[0046] Furthermore, the mud outlet 407 can take the upper, middle and lower layers of sludge, and each layer of sludge branch pipe is respectively provided with a sampling port (a sampling valve is respectively provided at the sampling port, which is the upper layer mud sampling valve 411, the middle layer mud sampling valve 412, and the lower layer mud sampling valve 413) and a branch pipe valve (which is the upper layer mud branch pipe valve 408, the middle layer mud branch pipe valve 409, and the lower layer mud branch pipe valve 410). Take samples from each layer respectively to measure the SVI (sludge volume index) of each sample or use other methods to detect sludge activity to determine the most suitable mud outlet height.

[0047] Further references Figures 3-4 A working bridge 417 is arranged on the top of the cyclone concentrating body 418, and the working bridge 417 is coaxially welded and fixed with the cyclone concentrating body 418. A reserved hole 501 is arranged at the center of the working bridge 417, and a prefabricated steel plate 502 is welded on the reserved hole 501. Bolt holes 503 are reserved on the prefabricated steel plate 502 for fixing and installing the agitator 403.

[0048] Further references Figure 2 A scraper 416 is provided in the conical bucket section of the cyclone thickening body 418, the agitator 403 is located in the straight cylinder section, and the scraper 416 is located below the agitator 403. The scraper 416 is used to prevent sludge from adhering to the side wall of the conical bucket section and accelerate the separation and collection of heavy phase sludge.

[0049] Furthermore, a mud discharge valve 419 is provided on the heavy phase mud discharge port 406, and the heavy phase sludge concentrated by the cyclone thickening body 418 is discharged from the system by opening the mud discharge valve 419 at the bottom.

[0050] Furthermore, a support leg 414 is provided on the outer side of the conical bucket section of the cyclone concentrating body 418, and the support leg 414 can be welded to the embedded iron reserved on the foundation ground or connected and fixed by anchor bolts.

[0051] The present invention provides a method for using an activated sludge selection and concentration device for sewage treatment, comprising:

[0052] Step 1, first open the pressure regulating valve 301 to 100%, start the air compressor 200 to build up the pressure to 0.8MPa, then start the sludge pump 100 to pump the nitrification liquid containing a large amount of activated sludge into the dissolving tank 300, and at the same time open the air outlet valve of the air compressor 200 to introduce the gas into the dissolving tank 300, and adjust the pressure regulating valve 301 to adjust the pressure gauge on the dissolving tank 300 to 0.4MPa, dissolve the activated sludge to be treated to form dissolved activated sludge, and send the dissolved activated sludge into the cyclone concentrator body 418 through the connecting pipeline.

[0053] Step 2, after the activated sludge with dissolved gas enters the cyclone thickening body 418, the activated sludge with dissolved gas releases a large number of extremely tiny bubbles under low pressure conditions (the cyclone thickening body 418 is a normal pressure environment) to improve the density gradient between different phases of the activated sludge, and preliminary stratification is performed by flotation. When the liquid level is above the uppermost blade, the agitator 403 is turned on to form a slow cyclone with a fixed speed in the body of the activated sludge with dissolved gas, and the different phases of sludge are accurately stratified by the effects of flotation and cyclone stratification.

[0054] Step 3. When the liquid level is about to cover the light phase sludge collecting weir 404, the sludge inlet is closed, and the light phase sludge mainly composed of oil, scum and expanded sludge is collected to the light phase sludge collecting weir 404 and then discharged from the system through the light phase sludge discharge port 405; then the upper layer mud sampling valve 411, the middle layer mud sampling valve 412, and the lower layer mud sampling valve 413 are opened respectively, and samples from the upper, middle and lower layer mud outlets are taken, and MLVSS / MLSS, SVI are tested respectively, or other methods for detecting sludge activity are used to determine the optimal mud outlet among the upper, middle and lower layer mud outlets.

[0055] Step 4: After determining the optimal mud outlet, start the mud outlet, open the corresponding upper mud outlet branch valve 408, middle mud outlet branch valve 409 or lower mud outlet branch valve 410, return the high-quality activated sludge to the biochemical system, and at the same time open the mud discharge valve 419 on the heavy phase sludge discharge port 406 to discharge the heavy phase sludge.

[0056] Further explanation based on steps 1 to 4:

[0057] In step 1, the air source pressure of the air compressor 100 can be set in the range of 0.6 to 0.8 MPa, the air-water volume ratio is 0.05 to 0.1, and the dissolved gas pressure can be set in the range of 0.3 to 0.5 MPa;

[0058] In step 2, the agitator 403 is a variable frequency agitator, and the speed can be adjusted by setting the operating frequency. The speed can be set at 3 to 50 rpm, and the appropriate speed is determined according to the sludge activity measured at the sludge outlet;

[0059] In steps 1 to 4, only perform the above steps 1 to 4 when the equipment is turned on for the first time or after it is emptied. After normal operation, you only need to turn on / off the mud inlet.

[0060] The advantages of the present invention are:

[0061] The present invention can be applied to the quality improvement scenarios of biochemical systems with poor pretreatment effect, sludge swelling and serious sludge inorganicization; it can completely solve the problem of poor separation effect of cyclone for sludge particle change gradient; it is multifunctional and can not only accurately and efficiently select high-quality activated sludge, but also concentrate the remaining sludge, reducing the investment in additional sludge concentration tanks; it can be made into modular standardized production and assembly equipment, and can also be made into small integrated mobile emergency equipment, which is easy to install; it can select and concentrate the activated sludge of the original system as an additional system without changing the original process route or stopping production; it has low investment cost, simple operation, small footprint, wide range of use, and high economy, flexibility and ecological and environmental protection value.

[0062] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An activated sludge selection and concentration device for sewage treatment, characterized in that: include: dissolved air systems and sludge selection and thickeners; The gas dissolving system is used to dissolve gas in the activated sludge to be treated under high pressure to form gas-dissolving activated sludge; The sludge selection and thickening machine is used to decompress the dissolved air activated sludge and release the bubbles; Under the stirring action of the agitator with adjustable speed, the light phase components in the sludge float to the surface of the liquid and are discharged from the top through the flotation effect of bubbles and the vortex generated by stirring, the heavy phase components containing inorganic sludge are discharged from the bottom, and the high-quality phase sludge in the middle layer is collected from the middle for return to the biochemical system.

2. The activated sludge selection and concentration device for sewage treatment according to claim 1, characterized in that: The dissolved gas pressure of the activated sludge to be treated is 0.3-0.5MPa.

3. The activated sludge selection and concentration device for sewage treatment according to claim 1 or 2, characterized in that: The air dissolving system comprises: a sludge pump, an air compressor and an air dissolving tank; The sludge pump and the air compressor are both connected to the gas dissolving tank, and a pressure regulating valve is provided on the connecting pipeline between the gas dissolving tank and the sludge selection and thickening machine; the activated sludge to be treated is sucked by the sludge pump and pumped into the gas dissolving tank, and the air compressor provides a gas source with a pressure of 0.7-0.8MPa to enter the gas dissolving tank, and the gas-water mixed pressure in the gas dissolving tank is adjusted to 0.3-0.5MPa by adjusting the pressure regulating valve, and the activated sludge to be treated is dissolved to form dissolved activated sludge.

4. The activated sludge selection and concentration device for sewage treatment according to claim 1, characterized in that: The sludge selection and thickening machine comprises: a cyclone thickening machine body; The cyclone concentrator body is composed of an upper straight cylinder section and a lower conical bucket section; A stirrer with adjustable speed is installed on the top of the straight cylinder section, and the blades of the stirrer are placed inside the straight cylinder section; A mud inlet pipe is arranged at the upper part of the straight tube section, and the mud inlet pipe is connected to the dissolved gas system. A guide tube connected to the mud inlet pipe is arranged in the cyclone concentrator body; A heavy phase sludge discharge port is provided at the bottom of the conical bucket section, a light phase sludge collecting weir is provided in the straight cylinder section, the light phase sludge collecting weir is higher than the paddles of the agitator, a light phase sludge discharge port connected to the light phase sludge collecting weir is provided on the straight cylinder section, and a mud outlet for collecting high-quality phase sludge is provided in the middle of the straight cylinder section.

5. The activated sludge selection and concentration device for sewage treatment according to claim 4, characterized in that: The stirring shaft of the stirrer is located on the axis of the cyclone concentrating body, the guide tube is coaxially arranged with the stirring shaft of the stirrer, and the lower discharge port of the guide tube is higher than the upper blades of the stirrer.

6. The activated sludge selection and concentration device for sewage treatment according to claim 4, characterized in that: A mud scraper is arranged in the conical bucket section.

7. The activated sludge selection and concentration device for sewage treatment according to claim 4, characterized in that: The heavy phase sludge discharge port is provided with a sludge discharge valve.

8. The activated sludge selection and concentration device for sewage treatment according to claim 4, characterized in that: A working bridge is welded on the top of the straight cylinder section, a reserved hole is arranged at the center of the working bridge, a prefabricated steel plate is welded on the reserved hole, and bolt holes are reserved on the prefabricated steel plate for fixing and installing the agitator.

9. The activated sludge selection and concentration device for sewage treatment according to claim 4, characterized in that: A plurality of mud outlet branch pipes are connected in parallel to the feed end of the mud outlet, and the plurality of mud outlet branch pipes are respectively connected to different heights of the straight tube section, and each mud outlet branch pipe is provided with a mud outlet branch pipe valve and a mud outlet sampling valve.

10. The activated sludge selection and concentration device for sewage treatment according to claim 9, characterized in that: Samples at different heights are taken for testing through the mud sampling valve, and the optimal mud branch pipe is determined based on the test results; then, the mud branch pipe valve on the optimal mud branch pipe is opened and the mud branch pipe valves on the remaining mud branch pipes are closed to collect high-quality sludge.

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