Continuous flow aerobic sludge granulation screening device and application

Abstract

The invention provides a continuous flow aerobic sludge granulation screening device and application. The whole structure of the device is divided into an upper part and a lower part; the upper part adopts a cylindrical or cubic structure, the lower part adopts an inverted conical structure, and the height-diameter ratio range is 1-10. The internal structure of the device is sequentially divided into an outflow area, a buffer area, a settling area and a sludge storage area from top to bottom. The hydraulic surface load range in the device is 1-9 m < 3 > / (m < 2 >. H). Wherein sludge separation facilities are arranged in the buffer area of the device, comprise but are not limited to inclined plates, inclined pipes, filter materials, baffles and the like, and are used for separating light floc and high-density coagulated sludge. The device can be directly mounted between a main flow biological reaction tank and a secondary sedimentation tank in a continuous flow sewage biological treatment process flow, and high-density sludge is screened through a sedimentation velocity selective pressure principle and a physical interception effect of a buffer area and is stably formed into granular sludge; the rapid transformation from flocculent sludge to granular sludge in a continuous flow biological sewage treatment process is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly relates to a continuous flow aerobic sludge granulation screening device and its application. Background Art

[0002] Aerobic granular sludge (AGS) is a granular sludge aggregate formed by the self-flocculation of activated sludge microorganisms under specific conditions. Compared with conventional activated sludge (CAS), AGS has a high biomass, excellent sedimentation performance, and strong pollutant removal ability. These characteristics enable it to operate efficiently with low energy consumption in a smaller occupied space, and can effectively inhibit operational problems such as sludge bulking and water quality fluctuations.

[0003] Currently, the engineering application of AGS technology mainly relies on sequencing batch reactors (SBR). In the SBR system, the formation of AGS can be promoted by creating an alternating "feast-starvation" environment, selective substrate supply, and selective scouring mechanisms. However, most of the current sewage biological treatment processes operate in the form of continuous flow flocculent sludge, and there is great potential for upgrading these processes to operate in the form of granular sludge. Therefore, developing AGS technology suitable for continuous flow processes has important practical significance.

[0004] In addition, by researching and developing a sludge granulation screening device and its application suitable for continuous flow sewage biological treatment processes, not only can the further development of AGS technology be promoted, but also its mature application can be obtained in a wider range of sewage treatment scenarios. The research and breakthrough of this technology will provide an efficient, economical, and sustainable solution for the sewage treatment industry. Summary of the Invention

[0005] An object of the present invention is to propose a continuous flow aerobic sludge granulation screening device and its application, providing a novel solution for sewage treatment technology to achieve continuous flow sewage biological treatment or capacity expansion operation (upgrading the process) or land saving (new process). The present invention can be directly embedded in the existing continuous flow sewage biological treatment process, and through the principle of sedimentation velocity selection pressure and buffer physical interception, the screening and stable formation of granular sludge are realized, so as to achieve the rapid transformation of flocculent sludge into granular sludge in the continuous flow sewage biological treatment process.

[0006] To achieve the above object of the present invention, the following technical solutions are specifically proposed:

[0007] A continuous-flow aerobic sludge granulation screening device, whose overall structure is divided into upper and lower parts; the upper part adopts a cylindrical or cubic structure, and the lower part is an inverted conical structure, with its height-diameter ratio designed in the range of 1 to 10. The internal structure of the device is successively divided into four functional zones from top to bottom: an effluent zone, a buffer zone, a sedimentation zone, and a sludge storage zone. The specific characteristics are as follows:

[0008] 1) An effluent weir is arranged at the upper part of the effluent zone of the device, which is convenient for the effluent and the overflow discharge of low-density sludge;

[0009] 2) A sludge physical interception device is arranged in the buffer zone of the device, including but not limited to forms such as inclined plates, inclined tubes, filter media, baffles, etc., which are used for physically intercepting high-density sludge with the potential to form granular sludge;

[0010] 3) The lower part of the sedimentation zone of the device is the water inlet point, and the water inlet method can be water inlet through a perforated flower wall or a central water inlet pipe;

[0011] 4) High-density sludge is enriched in the sludge storage zone of the device, and the latter can be refluxed through methods such as air-lift reflux, screw pump, axial flow pump, etc.;

[0012] 5) The designed range of the hydraulic surface load (upward flow velocity) in the device is 1 to 9 m 3 / (m 2 ·h), which is used to create a sedimentation velocity selection pressure environment, screen out flocculent sludge, and promote the formation and maintenance of stable granular sludge.

[0013] A method for promoting the formation of granular sludge, which is based on the above-mentioned continuous-flow aerobic sludge granulation screening device, and includes the following steps:

[0014] S1. Determine the size of the above-mentioned continuous-flow aerobic sludge granulation screening device according to the water treatment volume and sludge reflux volume of the continuous-flow sewage biological treatment process, and carry out processing;

[0015] S2. Install the processed continuous-flow aerobic sludge granulation screening device in step S1 after the biological reaction tank and before the secondary sedimentation tank in the continuous-flow sewage biological treatment process as a granular sludge screening device. Specifically, the muddy water mixture flowing out of the mainstream biological reaction tank flows into the above-mentioned continuous-flow aerobic sludge granulation screening device, and its effluent flows into the subsequent secondary sedimentation tank, and the high-density sludge enriched in the sludge storage zone of the above-mentioned continuous-flow aerobic sludge granulation screening device is refluxed to the mainstream biological reactor. The secondary sedimentation tank in the continuous-flow sewage biological treatment process no longer undertakes the sludge reflux function, but only collects the low-density flocculent sludge flowing out of the above-mentioned continuous-flow aerobic sludge granulation screening device;

[0016] S3. During the operation of the continuous-flow sewage biological treatment process, the sludge-water mixture flowing out of the mainstream biological reaction tank enters the described continuous-flow aerobic sludge granulation screening device. Under the screening effect of a relatively high hydraulic surface load (upward flow velocity) on the sludge in the device, the high-density sludge continuously deposits in the sludge storage area; the sludge with a sub-high density but the potential to form granular sludge is physically intercepted in the buffer area and gradually precipitates to the sludge storage area; the low-density flocculent sludge flows out of the system through the buffer area and the outflow area and directly enters the secondary sedimentation tank.

[0017] By continuously enriching the high-density sludge and removing the low-density sludge, the complete transformation of flocculent sludge into granular sludge is ultimately achieved, thereby increasing the sludge concentration in the continuous-flow sewage biological treatment process and operating efficiently. Through the above method, the formation of granular sludge can be effectively promoted, and the continuous-flow granular sludge biological treatment process can be realized.

[0018] Further optimizing the technical solution, the described continuous-flow aerobic sludge granulation screening device can achieve synchronous operation of multiple groups in a modular parallel manner, and during the startup process, the sedimentation velocity selection pressure and the degree of sludge granulation are gradually increased by gradually reducing the number of operating module groups, thereby further ensuring the stable transformation of flocculent sludge into granular sludge morphology and the stable operation effect in the continuous-flow sewage biological treatment process.

[0019] The present invention has the following advantages and effects:

[0020] (1) The continuous-flow aerobic sludge granulation screening device proposed by the present invention is an in-situ transformation device for the existing continuous-flow sewage biological treatment process, which can be directly installed between the mainstream biological reaction tank and the secondary sedimentation tank without significantly modifying the existing process.

[0021] (2) The buffer layer arranged inside the continuous-flow aerobic sludge granulation screening device proposed by the present invention can effectively intercept the sludge with the potential to form granular sludge while screening out the low-density flocculent sludge. This can not only significantly shorten the sludge granulation period but also avoid the problem of excessive sludge loss during the rapid granulation process.

[0022] (3) The continuous-flow aerobic sludge granulation screening device and its application proposed by the present invention can effectively ensure the uninterrupted operation of the process and good and stable effluent while achieving rapid granulation.

[0023] (4) The continuous-flow aerobic sludge granulation screening device and its application proposed by the present invention can achieve the rapid cultivation of aerobic granular sludge in the continuous-flow sewage biological treatment process and stable, efficient, and low-cost continuous operation. Description of the Drawings

[0024] To more clearly illustrate the specific embodiments of the present invention or the solutions in the prior art, the following provides a brief introduction to the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 Schematic diagram of a continuous-flow aerobic sludge granulation screening device provided by an embodiment of the present invention;

[0026] Figure 2 Schematic diagram of the application of a sludge granulation screening device suitable for continuous-flow sewage biological treatment process to the oxidation ditch process provided by an embodiment of the present invention;

[0027] Figure 3 For an A provided by an embodiment of the present invention for a sludge granulation screening device suitable for continuous-flow sewage biological treatment process 2 / O process schematic diagram;

[0028] Figure 4 Schematic diagram of the application of a continuous-flow aerobic sludge granulation screening device provided by an embodiment of the present invention to the UCT process;

[0029] Figure 5 Schematic diagram of the application of a continuous-flow aerobic sludge granulation screening device provided by an embodiment of the present invention to the membrane module in the alternative MBR process. Specific embodiments

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the present invention, rather than all the embodiments. The components and devices of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the present invention to be protected, but only represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0031] The present invention will be further described below with reference to the drawings and specific embodiments.

[0032] A continuous-flow aerobic sludge granulation screening device, characterized in that the overall structure of the device is divided into upper and lower parts; the upper part adopts a cylindrical or cubic structure, and the lower part is an inverted conical structure, and its height-diameter ratio (H / D) ranges from 1 to 10, including but not limited to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. The internal structure of the device is divided into four functional areas from top to bottom: an effluent area, a buffer area, a sedimentation area, and a sludge storage area.

[0033] The above-mentioned continuous-flow aerobic sludge granulation screening device is characterized in that a weir is arranged at the upper part of the effluent area to facilitate the effluent and the overflow of low-density sludge.

[0034] The above-mentioned continuous-flow aerobic sludge granulation screening device is characterized in that a sludge physical interception facility is arranged in the buffer area, including but not limited to forms such as inclined plates, inclined tubes, filter media, baffles, etc., for physically intercepting high-density sludge with the potential to form granular sludge.

[0035] The above-mentioned continuous-flow aerobic sludge granulation screening device is characterized in that the lower part of the sedimentation area is the water inlet point, and the water inlet method can be water inlet through a perforated flower wall or a central water inlet pipe.

[0036] The above-mentioned continuous-flow aerobic sludge granulation screening device is characterized in that high-density sludge is enriched in the sludge storage area, and the latter can be refluxed by means such as air-lift reflux, screw pump, axial flow pump, etc.

[0037] The above-mentioned continuous-flow aerobic sludge granulation screening device is characterized in that the hydraulic surface load (upward flow velocity) in the device is designed in the range of 1 to 9 m 3 / (m 2 ·h), including but not limited to 1 m 3 / (m 2 ·h), 2 m 3 / (m 2 ·h), 3 m 3 / (m 2 ·h), 4 m 3 / (m 2 ·h), 5 m 3 / (m 2 ·h), 6 m 3 / (m 2 ·h), 7 m 3 / (m 2 ·h), 8 m 3 / (m 2 ·h), 9 m 3 / (m 2 ·h).

[0038] Example 1: General application method of a continuous-flow aerobic sludge granulation screening device

[0039] Based on the above-mentioned continuous-flow aerobic sludge granulation screening device (as Figure 1 shown), the present embodiment discloses a method for promoting the formation of granular sludge, comprising the following steps:

[0040] S1. Determine the size of the above-mentioned continuous-flow aerobic sludge granulation screening device according to the water treatment capacity and sludge return flow rate of the continuous-flow sewage biological treatment process, and carry out processing;

[0041] S2. Install the processed continuous-flow aerobic sludge granulation screening device in step S1 after the biological reaction tank and before the secondary sedimentation tank in the continuous-flow sewage biological treatment process as a granular sludge screening device. Specifically, the muddy water mixture flowing out of the mainstream biological reaction tank flows into the above-mentioned continuous-flow aerobic sludge granulation screening device, and its effluent flows into the subsequent secondary sedimentation tank, and the high-density sludge enriched in the sludge storage area of the above-mentioned continuous-flow aerobic sludge granulation screening device is returned to the mainstream biological reactor. The secondary sedimentation tank in the continuous-flow sewage biological treatment process no longer undertakes the sludge return function, but only collects the low-density flocculent sludge flowing out of the above-mentioned continuous-flow aerobic sludge granulation screening device;

[0042] S3. During the operation of the continuous-flow sewage biological treatment process, the muddy water mixture flowing out of the mainstream biological reaction tank enters the above-mentioned continuous-flow aerobic sludge granulation screening device. Under the screening effect of a relatively high hydraulic surface load (upward flow velocity) on the sludge in the device, the high-density sludge continuously deposits in the sludge storage area; the sludge with the second highest density but having the potential to form granular sludge is physically intercepted in the buffer area and gradually settles to the sludge storage area; the low-density flocculent sludge flows out of the system through the buffer area and the effluent area and directly enters the secondary sedimentation tank;

[0043] By continuously enriching the high-density sludge and removing the low-density sludge, the complete transformation of flocculent sludge into granular sludge is finally realized, thereby increasing the sludge concentration in the continuous-flow sewage biological treatment process and operating efficiently. Through the above method, the formation of granular sludge can be effectively promoted, and the continuous-flow granular sludge biological treatment process can be realized.

[0044] The method for promoting the formation of granular sludge is characterized in that in step S2, the above-mentioned continuous-flow aerobic sludge granulation screening device can be operated synchronously in multiple groups in a modular parallel manner, and during the start-up process, the sedimentation velocity selection pressure and the degree of sludge granulation are gradually increased by gradually reducing the number of operating module groups, so as to further ensure the smooth transformation of flocculent sludge into granular sludge form and the stable operation effect in the continuous-flow sewage biological treatment process.

[0045] Example 2: Application of a continuous-flow aerobic sludge granulation screening device to the oxidation ditch process

[0046] As a simple and mature variant of the activated sludge process, the oxidation ditch process has become one of the main continuous-flow treatment processes adopted for urban sewage in China. This process usually presents in the form of a closed annular ditch, forming a circulating flow through internal aeration and pushing devices, so that pollutants such as suspended impurities, organic matter and ammonia nitrogen in the sewage are removed under the action of hydraulic scouring and microbial degradation.

[0047] The sludge granulation screening device can be introduced into the oxidation ditch process, such as Figure 2 shown. Under the action of the sedimentation velocity selection pressure created by the device, low-density flocculent sludge is continuously screened out into the secondary sedimentation tank and enters the subsequent sludge treatment process. The remaining high-density granular sludge is then refluxed into the oxidation ditch. This can not only continuously enrich granular sludge in the oxidation ditch process by physical means, but also further promote the self-aggregation of flocculent sludge to form granular sludge. More importantly, during the granulation process, the sludge physical interception facilities set in the buffer zone of the device can promote the formation of aerobic granular sludge by intercepting sludge with the potential to form granular sludge, and avoid the system collapse problem caused by excessive sludge loss. This can ensure the smooth transformation of flocculent sludge to granular sludge morphology and the stable operation effect in the oxidation ditch process. Finally, after successfully constructing the oxidation ditch aerobic granular sludge process, the sludge sedimentation performance, biomass and pollutant treatment efficiency in the process will be greatly improved, thereby reducing the process operation cost, chemical consumption and energy consumption.

[0048] Example 3: Application of a continuous-flow aerobic sludge granulation screening device to A 2 / O process

[0049] Anaerobic-anoxic-aerobic process (A 2 / O process) is a commonly used continuous-flow sewage denitrification and phosphorus removal process, which includes three parts: anaerobic section, anoxic section and aerobic section, as Figure 3 shown. The A 2 / O process constructs an anaerobic, anoxic and aerobic environment for sewage. This enables microorganisms with different survival condition requirements and metabolic functions to grow and reproduce simultaneously in the process flow, and achieve the removal of pollutants in the sewage, especially the denitrification and phosphorus removal effect.

[0050] The sludge granulation screening device can be introduced into the A 2 / O process, such as Figure 3 shown. Under the action of the sedimentation velocity selection pressure created by the device, low-density flocculent sludge is continuously screened out into the secondary sedimentation tank and enters the subsequent sludge treatment process. The remaining high-density granular sludge is then refluxed into the biological reaction tank. This can not only in A 2In the A / O process, granular sludge is continuously enriched by physical means, and it can further promote the self-aggregation of flocculent sludge to form granular sludge. More importantly, during the granulation process, the sludge physical interception facility set in the buffer zone of the device can promote the formation of aerobic granular sludge by intercepting the sludge with the potential to form granular sludge, and avoid the system collapse problem caused by excessive sludge loss. This can ensure the smooth transformation of flocculent sludge into granular sludge and the stable operation effect of the A / O process. Finally, after successfully constructing the A / O aerobic granular sludge process, the sludge sedimentation performance, biomass, and pollutant treatment efficiency in the process will be greatly improved, thereby reducing the process operation cost, chemical consumption, and energy consumption. 2 In the A / O process, the smooth transformation of flocculent sludge into granular sludge and the stable operation effect of the process. 2 After successfully constructing the A / O aerobic granular sludge process, the sludge sedimentation performance, biomass, and pollutant treatment efficiency in the process will be greatly improved, thereby reducing the process operation cost, chemical consumption, and energy consumption.

[0051] Example 4: A continuous-flow aerobic sludge granulation screening device is applied to the UCT process

[0052] As described in Example 2, 2 In the A / O process, phosphorus removal from sewage is achieved through the characteristics of polyphosphate-accumulating organisms of "anaerobic phosphorus release" and "aerobic phosphorus uptake"; sewage denitrification is achieved by returning the mixed liquor / nitrified liquid in the aerobic section to the anoxic section; and a part of the sludge concentrated in the secondary sedimentation tank is returned to the anaerobic section to maintain the microbial concentration and reaction activity in the process. However, the nitrate carried in the returned sludge will destroy the anaerobic environment in the anaerobic section, induce the competition for carbon sources between denitrifying bacteria and polyphosphate-accumulating organisms, and thus weaken the biological phosphorus removal ability. Therefore, in the UCT process, the sludge is returned to the anoxic section, and the return of the mixed liquor from the anoxic section to the anaerobic section is increased, as Figure 4 shown. This can not only ensure the good phosphorus release ability of polyphosphate-accumulating organisms in the anaerobic section, but also enhance the alternating cycle of anaerobic and anoxic environments in the process and improve the denitrifying phosphorus removal ability.

[0053] The sludge granulation screening device can be introduced into the UCT process, as Figure 4 shown. Under the action of the sedimentation velocity selection pressure created by the device, the low-density flocculent sludge is continuously screened out and sent to the secondary sedimentation tank and enters the subsequent sludge treatment process. The remaining high-density granular sludge is returned to the biological reaction tank. This can not only continuously enrich granular sludge by physical means in the UCT process, but also further promote the self-aggregation of flocculent sludge to form granular sludge. More importantly, during the granulation process, the sludge physical interception facility set in the buffer zone of the device can promote the formation of aerobic granular sludge by intercepting the sludge with the potential to form granular sludge, and avoid the system collapse problem caused by excessive sludge loss. This can ensure the smooth transformation of flocculent sludge into granular sludge and the stable operation effect of the UCT process. Finally, after successfully constructing the UCT aerobic granular sludge process, the sludge sedimentation performance, biomass, and pollutant treatment efficiency in the process will be greatly improved, thereby reducing the process operation cost, chemical consumption, and energy consumption.

[0054] Example 5: An apparatus for screening continuous-flow aerobic sludge granulation is applied to replace the membrane separation module in the MBR process

[0055] A membrane bioreactor (MBR) is a new type of sewage treatment process that combines membrane separation with traditional sewage biological treatment technology, as Figure 5 shown. This technology replaces the secondary sedimentation tank in the traditional activated sludge process through efficient membrane separation, and at the same time realizes the separation of mud and water and sludge concentration, aiming to solve the problems of low efficiency of mud and water separation and difficulty in maintaining a high concentration of system biomass in the traditional activated sludge process. However, although the MBR process has advantages such as good effluent quality and small footprint, it has practical problems that cannot be ignored in actual applications, such as high cost, high energy consumption, and membrane fouling.

[0056] In this regard, an apparatus for screening continuous-flow aerobic sludge granulation can be applied to replace the membrane separation module in the MBR process, as Figure 5 shown. Under the condition of the sedimentation velocity selection pressure created by the apparatus and the action of the sludge physical interception facility, the flocculent sludge in the continuous-flow sewage biological treatment process can be quickly transformed into the form of granular sludge. Finally, after successfully constructing the continuous-flow aerobic granular sludge process, the sludge sedimentation performance, biomass, and pollutant treatment efficiency in the process will be greatly improved. This can not only improve the efficiency of mud and water separation and sludge concentration from the perspective of the sludge itself, thereby improving the effluent quality, reducing the land occupation and sludge production, but also avoid the unnecessary problems of high cost, high energy consumption, and membrane fouling in the MBR process, and realize the sustainable upgrade of the continuous-flow sewage treatment process.

[0057] It should be noted that the embodiments of the present invention are not limited to the examples given, and other processes with the same principle also belong to the protection scope. The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features therein. These modifications or replacements do not cause the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention in essence.

Claims

1. A continuous flow aerobic sludge granulation screening device, characterized in that: The overall structure of the device is divided into two parts: the upper part adopts a cylindrical or cubic structure, and the lower part is an inverted cone structure, with a height-to-diameter ratio (H / D) ranging from 1 to 10. The internal structure of the device is divided into four functional areas from top to bottom: outflow area, buffer area, sedimentation area and mud storage area.

2. The continuous flow aerobic sludge granulation screening device according to claim 1, characterized in that: A water outlet weir is arranged at the upper part of the outflow area to facilitate the discharge of water and overflow of low-density sludge.

3. The continuous flow aerobic sludge granulation screening device according to claim 1, characterized in that: The buffer zone is provided with a sludge physical retention device, including but not limited to inclined plates, inclined tubes, filter materials, baffles, etc., for physically retaining high-density sludge with the potential to form granular sludge.

4. The continuous flow aerobic sludge granulation screening device according to claim 1, characterized in that: The lower part of the sedimentation area is the water inlet point, and the water inlet method can be perforated wall water inlet or central water inlet pipe water inlet.

5. The continuous flow aerobic sludge granulation screening device according to claim 1, characterized in that: High-density sludge is enriched in the sludge storage area, and the latter can be returned through air lift reflux, screw pump, axial flow pump, etc.

6. According to claim 1, the hydraulic surface load (upward flow velocity) of the continuous flow aerobic sludge granulation screening device is designed to be within a range of 1 to 9 m 3 / (m 2 h), to create a sedimentation velocity selective pressure environment to screen out flocculent sludge and promote the formation and stability of granular sludge.

7. A method for promoting the formation of granular sludge, the method is based on the continuous flow aerobic sludge granulation screening device, comprising the following steps: S1. Determine the size of the continuous flow aerobic sludge granulation screening device according to the water volume and sludge return volume of the continuous flow sewage biological treatment process, and process it; S2. Install the continuous flow aerobic sludge granulation screening device processed in step S1 after the biological reaction tank and before the secondary sedimentation tank in the continuous flow sewage biological treatment process as a granular sludge screening device. Specifically, the mud-water mixture flowing out of the mainstream biological reaction tank flows into the continuous flow aerobic sludge granulation screening device, and the effluent is made to flow into the subsequent secondary sedimentation tank, and the high-density sludge enriched in the sludge storage area of ​​the continuous flow aerobic sludge granulation screening device is returned to the mainstream bioreactor. The secondary sedimentation tank in the continuous flow sewage biological treatment process no longer has the function of sludge return, but is only used to collect low-density flocculent sludge flowing out of the continuous flow aerobic sludge granulation screening device; S3. During the operation of the continuous flow sewage biological treatment process, the sludge-water mixture flowing out of the mainstream biological reaction tank enters the continuous flow aerobic sludge granulation screening device. In the device, under the screening effect of the higher hydraulic surface load (upward flow velocity) on the sludge, high-density sludge is continuously deposited in the sludge storage area; the sludge with the second highest density but the potential to form granular sludge is physically intercepted in the buffer zone and gradually precipitated to the sludge storage area; the low-density flocculent sludge flows directly into the secondary sedimentation tank through the buffer zone and the outflow zone outflow system; By continuously enriching high-density sludge and removing low-density sludge, the complete transformation of flocculent sludge into granular sludge is finally achieved, thereby increasing the sludge concentration in the continuous flow sewage biological treatment process and operating it efficiently. The above method can effectively promote the formation of granular sludge and realize the continuous flow granular sludge biological treatment process.

8. A method for promoting the formation of granular sludge according to claim 7, characterized in that: In step S2, the continuous flow aerobic sludge granulation screening device can realize multiple groups of synchronous operation in a modular parallel manner, and during the startup process, the sedimentation velocity selection pressure and the sludge granulation degree are gradually improved by gradually reducing the number of operating module groups, thereby further ensuring the smooth transition of flocculent sludge to granular sludge form in the continuous flow sewage biological treatment process and the stability of the process operation effect.

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