Continuous flow sludge rapid granulation system and process based on particle size separation

Abstract

The continuous flow sludge rapid granulation system based on particle size separation comprises a micro-aerobic tank, an aerobic tank, a precipitation device and a particle size separation device, the micro-aerobic tank is communicated with the aerobic tank, the precipitation device and the particle size separation device are both installed on the upper portion of the aerobic tank, the bottoms of the precipitation device and the particle size separation device are both communicated with the aerobic tank, the micro-aerobic tank is communicated with the precipitation device, and the particle size separation device is communicated with the precipitation device. And the precipitation device is communicated with the particle size separation device. Wherein the particle size separation device realizes screening and enrichment of granular sludge, and a continuous flow aerobic granular sludge system with a high granulation ratio is rapidly formed; the precipitation device can accelerate the formation of the granular sludge, and long-term stable operation of the granular sludge is ensured by coexistence of the precipitation device and the granular sludge; the outer-layer aerobic and inner-layer anoxic / anaerobic microenvironment can be used for synchronously removing phosphorus by nitrification and denitrification. The continuous flow aerobic granular sludge which operates stably for a long time and has good carbon, nitrogen and phosphorus removal performance can be rapidly cultured, in addition, investment is small, compatibility is easy, the occupied area and operation energy consumption are saved, and the method has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular, relates to a continuous flow sludge rapid granulation system and process based on particle size separation. Background Art

[0002] Aerobic granular sludge is a granular activated sludge formed by microorganisms under specific conditions. It has the advantages of large particle size, fast sedimentation rate, and simultaneous removal of carbon, nitrogen and phosphorus. Compared with the traditional activated sludge process, the aerobic granular sludge process can reduce land use by 25-75% and energy consumption by 20-50%. It is considered to be one of the most environmentally friendly wastewater biological treatment processes with the greatest potential to dominate the next century.

[0003] At present, the industrial application of aerobic granular sludge is concentrated in sequencing batch reactors, among which the Delft University of Technology and Royal Haskoning DHV launched Technology dominates. So far, The technology has been applied in more than 100 sewage treatment plants. The technology can only be applied to sequencing batch reactors, and has the disadvantages of complex operation and control, small processing volume, low equipment utilization rate, and incompatibility with the continuous flow operation mode of existing sewage treatment plants, which limits the promotion and application of aerobic granular sludge technology. The continuous flow aerobic granular sludge process is easy to operate and control and can be directly applied to existing sewage treatment plants. Therefore, how to quickly cultivate aerobic granular sludge in continuous flow is of great significance.

[0004] The research on continuous flow aerobic granular sludge mostly adopts an upflow reactor with a large aspect ratio and a sedimentation column with a short residence time to achieve granulation, but this is incompatible with the structures of existing sewage treatment plants, and the aerobic granular sludge cultivated has a large particle size and insufficient stability, and often disintegrates after long-term operation, making it difficult to apply in actual projects. To this end, the present invention provides a continuous flow sludge rapid granulation system and process based on particle size separation, which is well compatible with existing sewage treatment facilities, has simple operation control, large processing capacity, can operate stably and continuously for a long time, and can significantly reduce the existing sewage treatment plant footprint and operating energy consumption, and has good application prospects. Summary of the invention

[0005] In order to solve the above-mentioned problems existing in the prior art, the present invention provides a continuous flow sludge rapid granulation system and process based on particle size separation, which adopts a particle size separation device to screen and enrich the granular sludge, improves the particle size and proportion of the system granular sludge, and adopts a sedimentation device to accelerate the formation of aerobic granular sludge, thereby achieving the purposes of rapid granulation of sludge under continuous flow, simultaneous removal of carbon, nitrogen and phosphorus, and ensuring effluent water quality.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0007] A continuous flow sludge rapid granulation system based on particle size separation comprises a microaerobic tank, an aerobic tank, a sedimentation device and a particle size separation device. The bottom of the microaerobic tank and the bottom of the aerobic tank are connected by a channel. The sedimentation device and the particle size separation device are both installed on the upper part of the aerobic tank and the bottoms are connected to the aerobic tank. The microaerobic tank is connected to the sedimentation device, and the sedimentation device is connected to the particle size separation device.

[0008] The micro-aerobic pool comprises a micro-aerobic pool body, a water distribution channel, a water distribution pipe and an aeration device installed at the bottom of the micro-aerobic pool body; the water distribution channel is installed on one side of the micro-aerobic pool body; the water distribution pipe is connected to the water distribution channel and extends to the bottom of the micro-aerobic pool body.

[0009] The aerobic pool comprises an aerobic pool body and an aeration device installed at the bottom of the aerobic pool body.

[0010] The sedimentation device is provided with a three-phase separator, a water outlet weir and an air lift sludge return device. The top of the three-phase separator is provided with an air collecting port. One end of the air lift sludge return device leads to the bottom of the sedimentation device and the other end leads to a water distribution channel.

[0011] The particle size separation device comprises an air lift sludge device and a hydrocyclone; one end of the air lift sludge device is connected to the hydrocyclone, the connection point is a feed port, and the other end extends to the bottom of the sedimentation device. The top of the hydrocyclone is provided with an overflow port, and the bottom is provided with an underflow port connected to an aerobic tank.

[0012] A continuous flow sludge rapid granulation process based on particle size separation comprises the following steps:

[0013] Step 1: Inoculate activated sludge to make the sludge concentration in the microaerobic tank and the aerobic tank (measured in mixed liquor suspended solid concentration MLSS) 2-4 g / L;

[0014] Step 2: The sewage enters the micro-aerobic pool through the water distribution channel and the water distribution pipe. Under the weak aeration conditions of the micro-aerobic pool, the granular sludge forms a micro-environment with an aerobic outer layer and an anoxic / anaerobic inner layer, and simultaneous nitrification, denitrification and phosphorus removal occur;

[0015] Step 3: After the reaction in the micro-aerobic pool is completed, the mixed liquid of the micro-aerobic pool mud and water enters the aerobic pool body through the bottom channel of the micro-aerobic pool, and the residual organic matter and ammonia nitrogen are removed under the strong aeration conditions of the aerobic pool;

[0016] Step 4: After the reaction in the aerobic tank is completed, the aerobic tank mud-water mixture enters the sedimentation device through the bottom channel of the sedimentation device, and realizes gas-liquid-solid separation under the action of the three-phase separator; the separated gas enters the gas recovery device through the gas collecting port, and the effluent enters the next treatment unit through the effluent weir, and the sludge returns to the aerobic tank through the bottom channel of the sedimentation device; the air lift sludge reflux device returns the aerobic tank mud-water mixture to the water distribution channel in the micro-aerobic tank, and after mixing with sewage in the water distribution channel, it enters the micro-aerobic tank through the water distribution pipe, so as to achieve the purpose of system circulation and continuous and stable operation;

[0017] Step 5: The mud-water mixture at the bottom of the sedimentation device is transported to the particle size separation device by the air lift sludge device, and enters the hydrocyclone through the feed port to complete the particle size separation. The flocculent sludge with small particle size enters the sludge treatment unit through the overflow port, and the granular sludge with large particle size returns to the aerobic tank through the bottom flow port, thereby achieving the purpose of screening and enriching the granular sludge.

[0018] The flow rate of the air lift sludge return device in step 4 is 0.5 to 2 times the sewage flow rate.

[0019] The sludge discharge amount at the overflow port of the hydrocyclone in step 5 is the residual sludge amount.

[0020] The continuous flow sludge rapid granulation system and process based on particle size separation of the present invention has the following characteristics and beneficial effects:

[0021] The present invention adopts a particle size separation device to screen and enrich granular sludge, eliminates flocculent sludge, increases the particle size and proportion of system granular sludge, and can quickly form a continuous flow aerobic granular sludge system with a high granulation ratio; a sedimentation device is arranged in an aerobic tank to provide a stronger hydraulic shear force for the sludge, promotes the collision and aggregation of microorganisms and the secretion of extracellular polymers, and accelerates the formation of aerobic granular sludge; under the screening and enrichment of the particle size separation device and the high shear force of the aerobic tank, the granular sludge continuously forms and enriches new granular sludge while aging and decomposing, thereby ensuring the long-term stable operation of the granular sludge; under the weak aeration condition of the micro-aerobic tank, the granular sludge forms an outer aerobic layer and an inner anoxic / anaerobic microenvironment, which can cause synchronous nitrification, denitrification and phosphorus removal, and the effluent water quality is good.

[0022] The present invention does not require large-scale changes to existing facilities of the sewage treatment plant, has a small investment and is easily compatible; it eliminates the secondary sedimentation tank and saves the nitrification liquid backflow, significantly reducing the footprint and operating energy consumption of the existing sewage treatment plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a continuous flow sludge rapid granulation system based on particle size separation according to an embodiment of the present invention;

[0024] Numbers in the figure: 1 is the micro-aerobic tank body, 2 is the aerobic tank body, 3 is the sedimentation device, 4 is the particle size separation device, 5 is the water distribution channel, 6 is the water distribution pipe, 7 is the aeration device, 8 is the three-phase separator, 9 is the gas collecting port, 10 is the water outlet weir, 11 is the air lift sludge return device, 12 is the air lift sludge device, 13 is the hydrocyclone, 14 is the feed port, 15 is the overflow port, and 16 is the underflow port. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0026] like Figure 1 As shown, a continuous flow sludge rapid granulation system based on particle size separation of the present invention comprises a microaerobic tank, an aerobic tank, a sedimentation device 3 and a particle size separation device 4, the bottom of the microaerobic tank and the bottom of the aerobic tank are connected by a channel, the sedimentation device 3 and the particle size separation device 4 are both installed on the upper part of the aerobic tank, and the bottoms are connected to the aerobic tank, the microaerobic tank is connected to the sedimentation device 3, and the sedimentation device 3 is connected to the particle size separation device 4;

[0027] The micro-aerobic pool comprises a micro-aerobic pool body 1, a water distribution channel 5, a water distribution pipe 6 and an aeration device 7 installed at the bottom of the micro-aerobic pool body 1; the water distribution channel 5 is installed on one side of the micro-aerobic pool body 1; the water distribution pipe 6 is connected to the water distribution channel 5 and extends to the bottom of the micro-aerobic pool body 1;

[0028] The aerobic pool comprises an aerobic pool body 2 and an aeration device 7 installed at the bottom of the aerobic pool body 2;

[0029] The sedimentation device 3 is provided with a three-phase separator 8, a water outlet weir 10 and an air-lift sludge return device 11. The top of the three-phase separator 8 is provided with an air collecting port 9. One end of the air-lift sludge return device 11 is connected to the bottom of the sedimentation device 3, and the other end is connected to the water distribution channel 5.

[0030] The particle size separation device 4 includes an air lift sludge device 12 and a hydrocyclone 13; one end of the air lift sludge device 12 is connected to the hydrocyclone 13, and the connection point is a feed port 14, and the other end extends to the bottom of the sedimentation device 3. The top of the hydrocyclone 13 is provided with an overflow port 15, and the bottom is provided with an underflow port 16 connected to the aerobic tank.

[0031] A continuous flow sludge rapid granulation process based on particle size separation comprises the following steps:

[0032] Step 1: Inoculate activated sludge to make the sludge concentration in the microaerobic tank and the aerobic tank (measured in mixed liquor suspended solid concentration MLSS) to be 2-4 g / L;

[0033] Step 2: The sewage enters the micro-aerobic tank body 1 through the water distribution channel 5 and the water distribution pipe 6. Under the weak aeration condition of the micro-aerobic tank, the granular sludge forms a micro-environment with an aerobic outer layer and an anoxic / anaerobic inner layer, and simultaneous nitrification and denitrification and phosphorus removal occur;

[0034] Step 3: After the reaction in the microaerobic pool is completed, the microaerobic pool mud-water mixture enters the aerobic pool body 2 through the bottom channel of the microaerobic pool, and the residual organic matter and ammonia nitrogen are removed under the strong aeration condition of the aerobic pool;

[0035] Step 4: After the reaction in the aerobic tank is completed, the aerobic tank mud-water mixture enters the sedimentation device 3 through the bottom channel of the sedimentation device 3, and realizes gas-liquid-solid separation under the action of the three-phase separator 8; the separated gas enters the gas recovery device through the gas collecting port 9, and the effluent enters the next treatment unit through the effluent weir 10, and the sludge returns to the aerobic tank through the bottom channel of the sedimentation device 3; the air lift sludge reflux device 11 returns the aerobic tank mud-water mixture to the water distribution channel 5 in the micro-aerobic tank, and after mixing with sewage in the water distribution channel 5, it enters the micro-aerobic tank through the water distribution pipe 6, so as to achieve the purpose of system circulation and continuous and stable operation;

[0036] Step 5: The mud-water mixture at the bottom of the sedimentation device 3 is transported to the particle size separation device 4 by the air lift sludge device 12, and enters the hydrocyclone 13 through the feed port 14 to complete the particle size separation. The flocculent sludge with small particle size enters the sludge treatment unit through the overflow port 15, and the granular sludge with large particle size returns to the aerobic tank through the underflow port 16, so as to achieve the purpose of screening and enriching the granular sludge.

[0037] In the step 4, the flow rate of the air lift sludge return device 11 is 0.5 to 2 times of the sewage flow rate.

[0038] The sludge discharge amount from the overflow port 15 of the hydrocyclone 13 in step 5 is the residual sludge amount.

[0039] The dissolved oxygen concentrations in the microaerobic pool and the aerobic pool are both adjusted by the aeration device 7. The dissolved oxygen concentration in the microaerobic pool is lower than 0.5 mg / L, and the dissolved oxygen concentration in the aerobic pool is 0.5-5.0 mg / L.

[0040] Taking the transformation of the traditional AAO-oxidation ditch process into a continuous flow sludge rapid granulation process based on particle size separation of the present invention as an example, the original anoxic tank can be transformed into a micro-aerobic tank in the present invention by adding an aeration device, and the sedimentation device and the particle size separation device are installed on the upper part of the aerobic tank. The original internal reflux is transformed into an airlift sludge reflux device; the original anaerobic tank and the secondary sedimentation tank are cancelled to save land, and the original external reflux is omitted to reduce the operating energy consumption. The operation process is divided into a startup stage and a stable operation stage.

[0041] Start-up phase: Inoculate flocculent activated sludge to make the sludge concentration in the micro-aerobic tank and aerobic tank reach 2-4g MLSS / L. Under the high hydraulic shear force of the aerobic tank and the sludge screening and enrichment of the particle size separation device, the inoculated activated sludge is transformed into granular sludge, forming a mixed system of flocculent sludge and granular sludge with a particle size of >200μm accounting for more than 30%. The startup time is about 15-30 days. The effluent quality in the startup phase maintains the effluent quality of the original activated sludge process.

[0042] Stable operation stage: At this time, the proportion of granular sludge with a particle size of >200μm is as high as 60% to 80%, forming a continuous flow aerobic granular sludge system. Under the screening and enrichment of the particle size separation device and the high shear force of the aerobic tank, the granular sludge is aged and decomposed while continuously forming and enriching new granular sludge, ensuring the long-term stable existence of granular sludge. In the stable operation stage, the chemical oxygen demand of the effluent is <30mg / L, ammonia nitrogen <1.0mg / L, total nitrogen <10mg / L, total phosphorus <0.5mg / L, and suspended solids <10mg / L. Without the need to add additional carbon sources and dephosphorizers, the Class A standard in the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" (GB 18918-2002) can be met.

[0043] The present invention adopts a particle size separation device to screen and enrich granular sludge, eliminates flocculent sludge, increases the particle size and proportion of system granular sludge, and can quickly form a continuous flow aerobic granular sludge system with a high granulation ratio; by arranging a sedimentation device in the aerobic tank, the aeration area can be reduced, the aeration intensity can be increased, stronger hydraulic shear force can be provided for the sludge, the collision aggregation of microorganisms and the secretion of extracellular polymers can be promoted, and the formation of aerobic granular sludge can be accelerated; under the screening and enrichment of the particle size separation device and the high shear force of the aerobic tank, the granular sludge is decomposed during aging. At the same time, new granular sludge is continuously formed and enriched, ensuring the long-term stable operation of granular sludge; the airlift sludge return device is used to avoid mechanical crushing of granular sludge; under the weak aeration conditions of the micro-aerobic tank, the granular sludge forms an outer aerobic and inner anoxic / anaerobic microenvironment, which can cause simultaneous nitrification and denitrification phosphorus removal, without the need for additional carbon source and phosphorus removal agent. Among the various indicators of effluent, the chemical oxygen demand of effluent is <30mg / L, ammonia nitrogen <1.0mg / L, total nitrogen <10mg / L, total phosphorus <0.5mg / L, and suspended solids <10mg / L. It can meet the Class A standard in the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" (GB 18918-2002).

[0044] The present invention does not require large-scale changes to existing facilities in sewage treatment plants, has a small investment and is easily compatible; it eliminates the secondary sedimentation tank and saves the nitrification liquid backflow, has simple operation and control, a large processing capacity, and significantly reduces the footprint and operating energy consumption of existing sewage treatment plants.

[0045] The above embodiments are preferred implementation modes of the present invention, but are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A continuous flow sludge rapid granulation system based on particle size separation, characterized by: The invention comprises a microaerobic pool, an aerobic pool, a sedimentation device (3) and a particle size separation device (4). The bottom of the microaerobic pool and the bottom of the aerobic pool are connected by a channel. The sedimentation device (3) and the particle size separation device (4) are both installed on the upper part of the aerobic pool and the bottoms are connected to the aerobic pool. The microaerobic pool is connected to the sedimentation device (3), and the sedimentation device (3) is connected to the particle size separation device (4).

2. A continuous flow sludge rapid granulation system based on particle size separation according to claim 1, characterized in that: The micro-aerobic pool comprises a micro-aerobic pool body (1), a water distribution channel (5), a water distribution pipe (6), and an aeration device (7) installed at the bottom of the micro-aerobic pool body (1); the water distribution channel (5) is installed at one side of the micro-aerobic pool body (1); the water distribution pipe (6) is connected to the water distribution channel (5) and extends to the bottom of the micro-aerobic pool body (1).

3. The continuous flow sludge rapid granulation system based on particle size separation according to claim 1 is characterized by: The aerobic pool comprises an aerobic pool body (2) and an aeration device (7) installed at the bottom of the aerobic pool body (2).

4. The continuous flow sludge rapid granulation system based on particle size separation according to claim 1 is characterized by: The sedimentation device (3) is provided with a three-phase separator (8), a water outlet weir (10) and an air lift sludge return device (11); a gas collecting port (9) is provided at the top of the three-phase separator (8); one end of the air lift sludge return device (11) is connected to the bottom of the sedimentation device (3) and the other end is connected to the water distribution channel (5).

5. The continuous flow sludge rapid granulation system based on particle size separation according to claim 1 is characterized by: The particle size separation device (4) comprises an air-lift sludge device (12) and a hydrocyclone (13); one end of the air-lift sludge device (12) is connected to the hydrocyclone (13), and the connection point is a feed port (14), and the other end extends to the bottom of the sedimentation device (3); the top of the hydrocyclone (13) is provided with an overflow port (15), and the bottom is provided with an underflow port (16) connected to the aerobic tank.

6. A continuous flow sludge rapid granulation process based on particle size separation, characterized in that: The steps include: Step 1: Inoculate activated sludge to make the sludge concentration in the microaerobic tank and the aerobic tank (measured in mixed liquor suspended solid concentration MLSS) 2-4 g / L; Step 2: The sewage enters the micro-aerobic pool body (1) through the water distribution channel (5) and the water distribution pipe (6). Under the weak aeration conditions of the micro-aerobic pool, the granular sludge forms a micro-environment with an aerobic outer layer and an anoxic / anaerobic inner layer, and simultaneous nitrification, denitrification and phosphorus removal occur; Step 3: After the reaction in the microaerobic pool is completed, the microaerobic pool mud-water mixture enters the aerobic pool body (2) through the bottom channel of the microaerobic pool, and the residual organic matter and ammonia nitrogen are removed under the strong aeration condition of the aerobic pool; Step 4: After the reaction in the aerobic tank is completed, the aerobic tank mud-water mixture enters the sedimentation device (3) through the bottom channel of the sedimentation device (3), and gas-liquid-solid separation is achieved under the action of the three-phase separator (8); the separated gas enters the gas recovery device through the gas collecting port (9), the effluent enters the next treatment unit through the effluent weir (10), and the sludge returns to the aerobic tank through the bottom channel of the sedimentation device (3); the air lift sludge return device (11) returns the aerobic tank mud-water mixture to the water distribution channel (5) in the micro-aerobic tank, and after mixing with sewage in the water distribution channel (5), it enters the micro-aerobic tank through the water distribution pipe (6), thereby achieving the purpose of system circulation and continuous and stable operation; Step 5: The mud-water mixture at the bottom of the sedimentation device (3) is transported to the particle size separation device (4) by the air lift sludge device (12), and enters the hydrocyclone (13) through the feed port (14) to complete the particle size separation. The flocculent sludge with small particle size enters the sludge treatment unit through the overflow port (15), and the granular sludge with large particle size returns to the aerobic tank through the bottom flow port (16), thereby achieving the purpose of screening and enriching the granular sludge.

7. A continuous flow sludge rapid granulation process based on particle size separation according to claim 6, characterized in that: In step 4, the flow rate of the air lift sludge return device (11) is 0.5 to 2 times the sewage flow rate.

8. The continuous flow sludge rapid granulation process based on particle size separation according to claim 6, characterized in that: The amount of sludge discharged from the overflow port (15) of the hydrocyclone (13) in step 5 is the amount of residual sludge.

9. The continuous flow sludge rapid granulation process based on particle size separation according to claim 6, characterized in that: The particle size of the granular sludge is >200 μm, accounting for 60% to 80%.

10. The continuous flow sludge rapid granulation process based on particle size separation according to claim 6, characterized in that: The weak aeration means that the dissolved oxygen concentration is ≤0.5 mg / L, and the strong aeration dissolved oxygen concentration is controlled at 0.5-5.0 mg / L.

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