A continuous flow aerobic granular sludge biochemical system transformed from a sedimentation tank

Abstract

The present application discloses a continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation, which can be used to transform the sedimentation tank of an existing sewage treatment plant without the need for additional land or a new sewage treatment system, and can greatly reduce the cost of upgrading and transforming the sewage treatment plant. A number of independent treatment units are formed by setting high and low baffles, and the aeration volume and dissolved oxygen concentration can be controlled separately. The number of high and low baffles can also be flexibly increased to adjust the height-to-diameter ratio of the system, which can promote the formation of aerobic particles and the granulation degree of the granular sludge system, reduce ineffective aeration, and greatly reduce power consumption. The transformed biochemical system can fully meet the increasingly stringent drainage requirements.

Description

Technical Field

[0001] The present application relates to a continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation, belonging to the field of biological sewage treatment. Background Art

[0002] Currently, 55% of the world's population lives in urban areas; this figure is expected to increase to 68% by 2050. This will overwhelm existing municipal wastewater treatment plants and lack space to allow them to expand. In addition, many countries have gradually tightened the removal or recovery targets for nutrients (nitrogen and phosphorus) in sewage, and the traditional process design of existing wastewater treatment plants cannot flexibly increase functions to adapt to increased flow and more stringent effluent discharge standards. Moreover, the aging infrastructure exacerbates this problem.

[0003] Aerobic granular sludge (AGS) is mostly yellow-brown or white, and is a special form of biofilm structure, because they do not need to attach to any carrier to grow, but are formed by self-aggregation and aggregation. The surface of mature granular sludge is smooth and regular in shape, mostly spherical or ellipsoidal. It aggregates under certain conditions to form a compact structure, regular in shape, and good sedimentation microbial aggregates. The sedimentation rate is 10 to 15 times that of traditional flocculent sludge. Based on this, flocculent sludge can be selectively discharged (Wash out) from the system to enrich granular sludge and improve the sedimentation and separation efficiency of mud and water. Compared with the traditional activated sludge method, it has more advantages, such as small footprint, good sedimentation performance, high biomass concentration, high resistance to organic load and not easy to cause sludge swelling, and a single aerobic granular sludge can form aerobic zone, anoxic zone and anaerobic zone, which is conducive to biological nitrogen and phosphorus removal, and produces less sludge, etc. It is one of the most promising biological treatment technologies for sewage and wastewater.

[0004] The majority of aerobic granular sludge processes currently used in the market are This process was developed by Royal Haskoning DHV of the Netherlands in cooperation with Delft University of Technology in the Netherlands. The process is actually an intermittent sewage treatment process, which belongs to the SBR process. The existing aerobic granular sludge process is mainly concentrated in the SBR reactor, but the reactor has intermittent water inlet and outlet and cannot operate continuously. If it is to operate continuously, at least two or three SBR reactors must work in parallel. This method has low working efficiency and increases the floor space. At present, most sewage treatment projects adopt continuous flow processes. The existing intermittent aerobic granular sludge process is not conducive to promotion, especially for large-scale sewage treatment projects. In addition to technical reasons, the application of aerobic granular sludge engineering is not easy to integrate into existing continuous flow sewage treatment plants that rely on secondary sedimentation tanks to complete mud and water separation based on the SBR operation mode. The shortcomings of the process also include the water inlet stage. The process is introduced. The water intake and drainage are carried out simultaneously. During this process, the aeration is turned off, and the water is then introduced to push the water above out and overflow to the next treatment unit. The shortcoming here is that the water intake stage can be regarded as an anaerobic process, but because of the need for drainage, the anaerobic process cannot be stirred. Therefore, in this process, only a small part of the sludge can have a rich process, and only a small part of the sludge can absorb the organic matter in the sewage. There is also a lot of sludge that cannot absorb sufficient organic matter in the sewage during this water intake process, which makes the denitrification and denitrification effect weak in the anaerobic process and the polyphosphate bacteria cannot fully release phosphorus under anaerobic conditions, which is not conducive to the anaerobic growth of polyphosphate bacteria at this stage and the phosphorus absorption process in the aerobic stage, affecting the denitrification and dephosphorization effect of sewage.

[0005] In the past few decades, pilot studies and practical application cases have mainly focused on SBR reactors. However, this reactor has intermittent water inlet and discharge, cannot operate continuously, has a long aeration time, high energy consumption, and sludge disintegration will occur after a long operation time. At the same time, the amount of water treated is small, which is not suitable for large-scale sewage treatment engineering applications. In contrast, the continuous flow reactor has a simpler operation control system and low installation cost. At the same time, its continuous flow mode can treat a large amount of water and has low operating costs. At present, most large sewage treatment plants use continuous flow technology, and the research on AGS under continuous flow state has important application value. At the same time, there are few reports on continuous flow aerobic granular sludge reactors, especially fewer transformation projects for practical applications. Continuous flow AGS technology has received more and more attention in the field of sewage and wastewater treatment. On the one hand, it is because continuous flow treatment of sewage and wastewater is still the water inlet operation mode selected by most urban sewage treatment plants in my country. On the other hand, the continuous flow AGS cultivation has low operating costs and high economic benefits.

[0006] In contrast, the continuous flow reactor has a simpler operation control system, and the installation and modification costs are low. At the same time, its continuous flow mode can process a large amount of water and has low operating costs. At present, most large sewage treatment plants adopt continuous flow technology. The research on aerobic granular sludge under continuous flow state has important application value, reducing the modification costs of existing sewage treatment projects, which is more conducive to promotion. However, there are few reports on reactors for continuous flow aerobic granular sludge, especially fewer modification projects for practical applications. The existing continuous flow aerobic granular sludge technology patent, a continuous flow aerobic granular sludge sludge biochemical system (CN 114380395 A), the disadvantage of this technical solution is that most of the aerobic granular sludge does not go through the anaerobic stage, resulting in the low stability of these granular sludge. According to the formation conditions of aerobic granular sludge, the granulation degree of aerobic granular sludge in this technical solution is not high. According to the abundant influent stage in Mark van Loosdrech's starvation-abundance theory, anaerobic influent can promote the release of phosphorus by polyphosphate bacteria, provide an anaerobic environment for the slow growth of polyphosphate bacteria, and provide key environmental conditions for the formation of aerobic granular sludge.

[0007] The aerobic granular sludge system currently used in the market is an intermittent sewage treatment system, which is inconsistent with the continuous flow sewage treatment system of existing sewage treatment plants. In addition, the intermittent aerobic granular sludge treatment system is complicated to operate, has a small sewage treatment capacity, requires a large area to treat the same amount of sewage, has a low reactor utilization rate, has high requirements for instruments and equipment, and has a higher daily operation and management cost than the continuous flow aerobic granular sludge system. However, there are few process designs and practical applications for continuous flow aerobic granular sludge. Summary of the invention

[0008] According to one aspect of the present application, a continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation is provided, which can transform the sedimentation tank of an existing sewage treatment plant without the need for additional land and a new sewage treatment system, and can greatly reduce the cost of upgrading the sewage treatment plant. The transformed biochemical system can fully meet the increasingly stringent drainage requirements.

[0009] This application adopts the following technical solutions:

[0010] A continuous flow aerobic granular sludge biochemical system transformed from a sedimentation tank, comprising an anoxic tank, wherein the anoxic tank is surrounded by N-level sewage treatment tanks, 2≤N≤30; each level of sewage treatment tank is arranged around the sewage treatment tank of the previous level;

[0011] The sewage treatment tanks at each level are separated by partitions to form K treatment units arranged in sequence, 4≤K≤50;

[0012] The first treatment unit in each level of the sewage treatment tank is configured as a connection unit;

[0013] The anoxic tank is connected to the connection unit of the first-level sewage treatment tank, and the adjacent sewage treatment tanks are connected by the last treatment unit in the upper-level sewage treatment tank and the connection unit in the lower-level sewage treatment tank;

[0014] Except for the last treatment unit in the Nth-stage sewage treatment pool, the bottoms of the remaining treatment units and connecting units are all provided with M aeration holes, 1≤M≤100.

[0015] Optionally, the aeration holes are evenly dispersed.

[0016] The evenly dispersed aeration holes can flexibly add multiple aeration head controllers to control the dissolved oxygen concentration of the sewage treatment unit between the high and low partitions, forming aerobic, anoxic and even anaerobic pools, which can promote the denitrification and phosphorus removal effects, improve the stability of the aerobic granular sludge system and the degree of granulation. These controllers can also be used to adjust the aeration intensity, reduce ineffective aeration, and save energy.

[0017] The muddy sewage in the anoxic tank enters the connecting unit in the first-stage sewage treatment tank, then flows through each treatment unit of this stage in turn, and then flows from the last treatment unit of this stage into the connecting unit of the next-stage sewage treatment tank and continues to flow; the muddy sewage flows through each treatment unit in turn, and finally enters the sedimentation tank, where it is separated and discharged.

[0018] Optionally, the partition includes a first partition, a high partition and a low partition.

[0019] Optionally, the first partition is arranged between the connecting unit and the last treatment unit in each stage of the sewage treatment tank, and the remaining treatment units are formed by staggered isolation of high partitions and low partitions.

[0020] Optionally, a water outlet hole is provided at the bottom of the high partition.

[0021] Optionally, the muddy sewage flows alternately through the outlet holes at the bottom of the high baffles and the top of the low baffles.

[0022] The muddy sewage flows alternately through the outlet holes at the bottom of the high baffle and overflows from the top of the low baffle to the next treatment unit.

[0023] Specifically, the muddy sewage flows into the connecting unit of the first-level sewage treatment tank from the overflow port between the anoxic tank and the first-level connecting unit, then flows into the next treatment unit from the outlet hole at the bottom of a high partition of the connecting unit, and then overflows from the top of the low partition in the next treatment unit to the next unit. The muddy sewage flows circumferentially through each treatment unit in the above manner until it flows into the last treatment unit from the outlet hole at the bottom of the high partition, and then flows into the connecting unit in the second-level sewage treatment tank from the overflow port between the last treatment unit of the first-level sewage treatment tank and the connecting unit of the second-level sewage treatment tank, and continues to flow in the same manner as above until it flows into the last treatment unit in the Nth sewage treatment tank.

[0024] Optionally, an overflow port is provided at the top of the inner wall of the connection unit.

[0025] Optionally, in each stage of the sewage treatment tank, muddy sewage flows into the connecting unit from the overflow port.

[0026] Optionally, the height of the lower partition is 1-10% of the height of the high partition, and the number K of the processing units is an even number.

[0027] Optionally, the anoxic pool is surrounded by three-level sewage treatment pools, each of which is circular; each level of sewage treatment pool is separated by a partition to form 12 treatment units arranged in sequence.

[0028] Optionally, the aeration holes are all connected to an aeration blower through a compressed air pipeline; and each processing unit independently controls the aeration amount through the aeration holes.

[0029] The aeration blower can flexibly control the aeration intensity of the aeration holes, and control the aeration intensity and dissolved oxygen concentration in each treatment unit between the high and low partitions, thereby forming aerobic, anoxic and even anaerobic areas, which is very beneficial to the denitrification and phosphorus removal of sewage. Since the high and low partitions can be regarded as a small sewage treatment unit, by flexibly controlling the aeration intensity of these small sewage treatment units and reducing ineffective aeration, the power consumption can be greatly reduced. In addition, the alternation of aerobic, anoxic and even anaerobic areas is conducive to promoting the formation of aerobic granular sludge and improving stability.

[0030] Optionally, 2 to 10 submersible agitators are arranged on the inner wall of the anoxic tank.

[0031] Optionally, a water distribution system is provided at the bottom of the anoxic pool, and 2 to 100 water inlets are provided on the water distribution system.

[0032] Optionally, the water inlets are evenly distributed, and muddy sewage enters the biochemical system from the water inlets from bottom to top, which is conducive to flushing up the sludge at the bottom and mixing it evenly under the action of the submersible mixer.

[0033] The outer wall of the last treatment unit in the Nth-stage sewage treatment pool is provided with a 25% drainage hole, a 50% drainage hole, a 75% drainage hole, and a sludge discharge pipe in sequence from top to bottom.

[0034] The 25% drainage holes, 50% drainage holes, and 75% drainage holes distribution mean that the maximum amount of water that can be discharged from the sedimentation tank is The larger the value of 25% sewage, 50% sewage and 75% sewage by volume, the faster the drainage flow rate and the shorter the sludge settling time. By selecting different drainage holes, the sludge with a slower settling speed in the sewage can be discharged out of the system, and the sludge concentration of the system can also be controlled.

[0035] Optionally, a sump pump is included.

[0036] The upper sewage treatment unit is connected to the sewage pump via a pipeline with a valve.

[0037] The sewage pump is connected to the water distribution system through a mud-water mixed water inlet pipe.

[0038] The sludge discharge pipe is communicated with the sewage pump.

[0039] The sewage pump also includes a mud discharge pipeline.

[0040] The last treatment unit of the Nth-level sewage treatment pool can be regarded as a small sedimentation tank because there is no aeration hole. The sludge discharge pipe at the bottom of the unit can regularly discharge the residual sludge. Due to the anaerobic effect, the sludge is easier to dehydrate, saving the cost of dehydration agents. Overall, the sludge disposal cost is lower. At the same time, the residual sludge contains a large amount of alginate, which is conducive to resource recovery.

[0041] Optionally, after the sludge from the last treatment unit in the Nth-level sewage treatment pool enters the sewage pump through the sludge discharge pipe, part of the sludge is mixed with the sewage from the upper sewage treatment unit flowing into the sewage pump, and then flows into the water distribution system through the mud-water mixing inlet pipe; the other part of the sludge is discharged through the sludge discharge pipe on the sewage pump.

[0042] This application uses the rapid sedimentation and high solid concentration characteristics of AGS to integrate the sedimentation unit into the treatment unit, thereby eliminating the large secondary sedimentation tank and energy-intensive return facilities, which can greatly reduce the footprint of the entire plant and enhance the reactor operation treatment effect.

[0043] Due to the large volume of aerobic granular sludge, oxygen and substances in the water cannot all enter and penetrate into the core of the granules, thus forming a concentration gradient in the radial direction of the granules. For example, the closer to the sludge surface, the higher the oxygen concentration, forming an oxygen-rich zone near the surface; inward, it forms an anoxic zone and gradually transitions to the anaerobic zone in the core. In different partitions, there are respective dominant microbial populations, which has been confirmed by fluorescence in situ hybridization analysis. The structure and unique properties of the above-mentioned aerobic granular sludge enable it to achieve efficient removal of COD, total nitrogen, total phosphorus, etc. on one granular sludge.

[0044] The beneficial effects of this application include:

[0045] (1) The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation provided in this application can directly transform the existing sedimentation tank without increasing the civil construction area or additional land, which can greatly save the transformation cost. It is especially suitable for the transformation of large-scale sewage treatment projects with radial flow sedimentation tanks. Because it is a continuous flow aerobic granular biochemical process, after the transformation, the aerobic granular sludge concentration can reach 6-13g / L, and the sludge volume index SVI 30 It can reach below 50mL / g, has excellent sedimentation rate, and can greatly reduce the area of ​​sedimentation tank. The particle size of the aerobic granular sludge formed is between 0.2 and 2.5mm, and anaerobic zone, anoxic zone and aerobic zone can be formed from the inside to the outside of the particle size at one time. Different bacteria are distributed in different areas. Under the combined action of these bacteria, the denitrification and phosphorus removal effect of the sludge can be greatly improved. At the same time, due to the high sludge concentration, it can effectively resist the impact load of sewage and improve the efficiency and stability of sewage treatment. In addition, the amount of sludge produced by this aerobic granular sludge biochemical system is less than that of the traditional activated sludge biochemical system, which is conducive to reducing the subsequent sludge treatment costs.

[0046] (2) Compared with the traditional continuous flow, the continuous flow aerobic granular sludge biochemical system of the sedimentation tank transformation provided in the present application can flexibly increase the number of high and low baffles to adjust the height-to-diameter ratio of the system. Under the same aeration intensity, the larger the height-to-diameter ratio, the greater the shear force obtained by the sludge, which is more conducive to the formation of aerobic granular sludge. At the same time, there is a screening effect under the action of gravity. The heavier sludge particles are retained, while the lighter sludge is discharged with the water flow and enters the next treatment unit. Continuous screening is beneficial to improve the granulation degree of the aerobic granular sludge system.

[0047] (3) The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation provided by the present application can flexibly control the aeration intensity between the high and low partitions, thereby controlling the dissolved oxygen concentration of the sewage treatment units between the partitions, so that these sewage treatment units are aerobic, anoxic or even anaerobic, which greatly promotes nitrogen and phosphorus removal, promotes water quality to meet standards, and has strong impact resistance. Since the high and low partitions can be regarded as a small sewage treatment unit, by flexibly controlling the aeration intensity of the aeration holes in these small sewage treatment units and reducing ineffective aeration, power consumption can be greatly reduced.

[0048] (4) In the continuous flow aerobic granular sludge biochemical system of the sedimentation tank transformation provided in the present application, the sludge return and sewage inflow can be in the same pipeline, so that the sewage has a pushing and flushing effect on the sludge in the pipeline, which can prevent the sludge in the pipeline from being blocked, and at the same time also reduces the number of sewage pumps and saves energy consumption.

[0049] (5) In the circular pool at the center of the aerobic sludge granular biochemical system transformed from the sedimentation tank, anaerobic upflow water is introduced. At the same time, under the stirring action of the submersible agitator, the sludge and sewage can be almost completely mixed, perfectly meeting the abundant water inflow stage in Mark van Loosdrech's hunger-abundance theory, which is conducive to the release of phosphorus by polyphosphate bacteria, provides an anaerobic environment for the growth of polyphosphate bacteria, and provides key environmental conditions for the formation of aerobic granular sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the structure of the continuous flow aerobic granular sludge biochemical system for the sedimentation tank transformation in Example 1 of the present application;

[0051] Figure 2 This is a top view of the continuous flow aerobic granular sludge biochemical system of the sedimentation tank modification in Example 1 of the present application.

[0052] Reference numerals

[0053] 1. Upstream sewage treatment unit; 2. Aerobic granular sludge biochemical system for sedimentation tank transformation; 3. Aeration blower; 4. Valve; 5. Sewage pump; 6. Sludge discharge pipe; 7. Water inlet; 8. Submersible mixer; 9. Overflow port A; 10. Aeration hole; 11. High partition; 12. Water outlet; 13. Low partition; 14. Overflow port B; 15. Overflow port C; 16.25% drainage hole; 17.50% drainage hole; 18.75% drainage hole; 19. Sludge discharge pipe; 20. Mud-water mixed water inlet pipe; 21. Compressed air pipeline; 22. Small sedimentation tank; 23. Anoxic tank. DETAILED DESCRIPTION

[0054] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0055] Unless otherwise specified, the raw materials and in the examples of this application were purchased through commercial channels.

[0056] In the present application, the height-to-diameter ratio refers to the ratio of the height of the treatment unit to the bottom width. Under the same aeration intensity, the larger the height-to-diameter ratio, the stronger the shear force obtained by the sludge, which is conducive to promoting the particle formation of the sludge and improving the degree of granulation of the sludge.

[0057] According to an implementation method of the present application

[0058] The aerobic granular sludge biochemical system of the sedimentation tank transformation is transformed from the existing radial flow sedimentation tank of the sewage treatment plant. The water inlet method remains unchanged and adopts the bottom-up water inlet method. By enclosing the center of the radial flow sedimentation tank into a circle, only one overflow port is retained, and the sewage overflows from the top to the outer ring. Several submersible mixers are installed on the inner wall of the central circle. The bottom of the central circle is the water distribution system. The sewage and the return sludge are mixed and enter from the water distribution system. Under the action of the submersible mixer, they are evenly dispersed inside the central circle and then continuously inlet. The sewage overflows into the outer ring. There are high and low partitions in the outer ring. There are several aeration heads between the high partition and the low partition. Aeration is continuously provided to provide shear force for the sludge. When the distance between the partitions is smaller, the height-to-diameter ratio is larger, and the shear force provided under the same aeration intensity is greater, which is conducive to the formation of aerobic granular sludge. At the bottom of the high partition, there are holes for sewage to flow through, and the sewage flows into the next stage. Between the high partition and the low partition, the sewage does not pass through the low partition and enters the next stage. The sewage flows from bottom to top and then from top to bottom, and the aeration intensity can be flexibly controlled. The aerobic and anoxic conditions between the partitions can be controlled, which is beneficial to the nitrification and denitrification of bacteria, thereby reducing the concentration of ammonia nitrogen and total nitrogen in the sewage.

[0059] Sewage flows in from the bottom of the high partition and out from the top of the low partition, continuously flowing in and out of the small compartments inside the circle, and then enters the next circle through the overflow port between the rings, and repeats the cycle. The center of the radial flow sedimentation tank is the center of the circle. The flow trajectory of the water can be regarded as a circle, and the radius of the circle is constantly increasing. When it finally reaches the outermost layer, it flows in from the bottom hole of the high partition. At this time, there is no aeration system in the area where it flows in. At this time, the area is equivalent to a small sedimentation tank. Since aerobic granular sludge can settle quickly, and sewage flows from bottom to top at the same time, the supernatant can remain clear, and the treated clean water is discharged to the next treatment unit through the drainage hole. After the sludge is precipitated, it follows the sewage of the upper sewage treatment unit under the action of the sewage pump and enters the bottom of the radial flow sedimentation tank again, thus repeating the cycle.

[0060] Example 1

[0061] As attached Figure 1 and2 As shown, the continuous flow aerobic granular sludge biochemical system of the sedimentation tank transformation includes the aerobic granular sludge biochemical system of the sedimentation tank transformation (2) and the upper sewage treatment unit (1)

[0062] The aerobic granular sludge biochemical system (2) transformed from a sedimentation tank comprises an anoxic tank (23), and four submersible agitators (8) are arranged on the inner wall of the anoxic tank (23);

[0063] The anoxic pool (23) is surrounded by three levels of sewage treatment pools. As shown in the figure, each level of sewage treatment pool is arranged around the upper level of sewage treatment pool. Each level of sewage treatment pool is separated by a high partition (11) and a low partition (13) to form 12 treatment units arranged in sequence.

[0064] The first treatment unit in each stage of the sewage treatment pool is configured as a connection unit, and an overflow port is provided at the top of the inner wall of the connection unit. The overflow ports in each stage are overflow port A (9), overflow port B (14), and overflow port C (15). The partition between the first and twelfth treatment units is a high partition (11) without a water outlet (12), and the bottoms of the remaining high partitions (11) are all provided with a water outlet (12);

[0065] The anoxic tank (23) is connected to the connection unit of the first-stage sewage treatment tank, the 12th treatment unit of the first-stage sewage treatment tank is connected to the connection unit of the second-stage sewage treatment tank, and the 12th treatment unit of the second-stage sewage treatment tank is connected to the connection unit of the third-stage sewage treatment tank;

[0066] The last treatment unit in the third-stage sewage treatment pool can be regarded as a small sedimentation tank (22). Except for this treatment unit, the bottoms of the remaining treatment units and connecting units are provided with 3 to 6 evenly distributed aeration holes (10), and the aeration holes (10) are connected to the aeration blower (3) through a compressed air pipeline (21).

[0067] A water distribution system is provided at the bottom of the anoxic pool (23), and 50 water inlets (7) are provided on the water distribution system. The sewage pump (5) is connected to the water distribution system through a mud-water mixed water inlet pipe (20);

[0068] The outer wall of the last treatment unit in the third-stage sewage treatment pool is provided with a 25% drainage hole (16), a 50% drainage hole (17), a 75% drainage hole (18), and a sludge discharge pipe (19) from top to bottom, and the sludge discharge pipe (19) is connected to the sewage pump (5).

[0069] The upper sewage treatment unit (1) is connected to the sewage pump (5) via a pipeline with a valve (4). The sewage pump is also provided with a mud discharge pipeline (6).

[0070] The working process of the continuous flow aerobic granular sludge biochemical system transformed from the above sedimentation tank is as follows:

[0071] After the sewage is treated by the upper sewage treatment unit, it passes through the valve and the sewage pump mixes the sewage and the sludge discharged from the sedimentation tank, and then enters the aerobic granular sludge biochemical system of the sedimentation tank transformation through the mud-water mixing inlet pipe. Sewage and sludge enter from the bottom of the aerobic granular sludge biochemical system, and pass through the water distribution system at the bottom. Sewage comes out from 28 water inlets and enters the anoxic tank. Under the action of the submersible agitator on the inner wall of the anoxic tank, the sewage and the sludge at the bottom of the tank are fully mixed. After the anaerobic process, the sewage enters the connecting unit of the first-level sewage treatment tank on the periphery through the overflow port A under the action of continuous water inflow and submersible agitator. The aeration holes at the bottom of the connecting unit are continuously aerated to provide shear force to the sewage and promote the formation of aerobic granular sludge. Then, when the sewage flows between the partitions, it flows into the second treatment unit from the water outlet hole at the bottom of the high partition. Under the action of the water flow and the continuous aeration of the aeration holes at the bottom of the treatment unit, the sewage submerges the top of the low partition, and then flows to the next treatment unit. In the above manner, it flows through the treatment units between the high partition and the low partition one after another. Each treatment unit is aerated independently, and the sewage flows to the 12th treatment unit of the first-level sewage treatment tank. After the treatment unit, it flows into the connecting unit of the second-stage sewage treatment tank through the overflow port B, repeating the same sewage flow process as the first-stage sewage treatment tank. After the sewage flows to the 12th treatment unit of the second-stage sewage treatment tank, it flows into the connecting unit of the third-stage sewage treatment tank through the overflow port C, repeating the same sewage flow process as the first-stage sewage treatment tank. After the sewage flows to the 12th treatment unit of the third-stage sewage treatment tank, the treatment unit is not aerated, and the aerobic granular sludge in the sewage can be quickly precipitated. The supernatant can be discharged to the lower-level water treatment unit through three drainage holes of different heights, namely, 25% drainage hole, 50% drainage hole, and 75% drainage hole. After precipitation, the sludge flows into the sewage pump through the pipeline. Under the action of the sewage pump, part of the sludge follows the sewage of the upper sewage treatment unit to enter the anoxic tank of the continuous flow aerobic granular sludge biochemical system transformed from the sedimentation tank again, and the other part of the sludge is discharged through the sludge discharge pipe on the sewage pump.

[0072] Among them, the muddy sewage in the anoxic tank forms an anaerobic state due to the lack of air entering, which is conducive to the release of phosphate by polyphosphate bacteria in the return sludge. At the same time, polyphosphate bacteria absorb organic matter in sewage and promote the slow growth of polyphosphate bacteria. Polyphosphate bacteria use volatile organic acids and other organic matter in sewage to form poly-β-hydroxybutyrate under anaerobic conditions, which is conducive to the subsequent decomposition of poly-β-hydroxybutyrate under aerobic conditions, providing energy for polyphosphate bacteria to absorb phosphate, and reducing the phosphate content in the sewage supernatant, thereby achieving phosphorus removal. At the same time, in an anaerobic environment, the slow growth of polyphosphate bacteria can be promoted, and the polyphosphate bacteria at this time can provide a nucleus for the growth of aerobic granular sludge. Aerobic granular sludge with polyphosphate bacteria as the core will be more solid and stable, and in the subsequent sewage treatment process, the aerobic granular sludge will not flocculate.

[0073] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A continuous flow aerobic granular sludge biochemical system transformed from a sedimentation tank, characterized in that: It includes an anoxic pool, and the anoxic pool is surrounded by N-level sewage treatment pools, 2≤N≤30; each level of sewage treatment pool is arranged around the sewage treatment pool of the previous level; The sewage treatment tanks at each level are separated by partitions to form K treatment units arranged in sequence, 4≤K≤50; The first treatment unit in each level of the sewage treatment tank is configured as a connection unit; The anoxic tank is connected to the connection unit of the first-level sewage treatment tank, and the adjacent sewage treatment tanks are connected by the last treatment unit in the upper-level sewage treatment tank and the connection unit in the lower-level sewage treatment tank; Except for the last treatment unit in the N-th level sewage treatment pool, the bottoms of the remaining treatment units and connecting units are all provided with M aeration holes, 1≤M≤100; the last treatment unit in the N-th level sewage treatment pool is used as a small sedimentation tank; The muddy sewage in the anoxic tank enters the connecting unit in the first-stage sewage treatment tank, then flows through each treatment unit of this stage in turn, and then flows from the last treatment unit of this stage into the connecting unit of the next-stage sewage treatment tank to continue flowing; the muddy sewage flows through each treatment unit in turn, and finally enters the small sedimentation tank, and then the muddy sewage is separated and discharged.

2. The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation according to claim 1, characterized in that: The partition includes a first partition, a high partition and a low partition; The first partition is arranged between the connection unit and the last treatment unit in each stage of the sewage treatment tank, and the remaining treatment units are formed by staggered isolation of high partitions and low partitions; A water outlet hole is provided at the bottom of the high partition; The muddy sewage flows alternately through the outlet holes at the bottom of the high partition and the top of the low partition.

3. The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation according to claim 2, characterized in that: An overflow port is provided on the top of the inner wall of the connecting unit; In each stage of sewage treatment tank, muddy sewage flows into the connection unit from the overflow port.

4. The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation according to claim 2, characterized in that: The height of the low partition is 1-10% of the height of the high partition, and the number K of the processing units is an even number.

5. The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation according to claim 1, characterized in that: The anoxic pool is surrounded by a three-stage sewage treatment pool, and the sewage treatment pool is circular; Each level of sewage treatment tank is separated by partitions to form 12 treatment units arranged in sequence.

6. The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation according to claim 1, characterized in that: The aeration holes are all connected to the aeration blower through a compressed air pipeline; and each processing unit independently controls the aeration volume through the aeration holes.

7. The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation according to claim 1, characterized in that: 2 to 10 submersible agitators are arranged on the inner wall of the anoxic tank.

8. The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation according to claim 1, characterized in that: A water distribution system is provided at the bottom of the anoxic pool, and 2 to 100 water inlets are provided on the water distribution system; The outer wall of the last treatment unit in the Nth-stage sewage treatment pool is provided with a 25% drainage hole, a 50% drainage hole, a 75% drainage hole, and a sludge discharge pipe from top to bottom.

9. The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation according to claim 8, characterized in that: Also includes sump pump; The upper sewage treatment unit of the continuous flow aerobic granular sludge biochemical system transformed from the sedimentation tank is connected to the sewage pump through a pipeline with a valve; The sewage pump is connected to the water distribution system through a mud-water mixed water inlet pipe; The sludge discharge pipe is connected to the sewage pump; The sewage pump also includes a mud discharge pipeline.

10. The continuous flow aerobic granular sludge biochemical system for sedimentation tank transformation according to claim 9, characterized in that: After the sludge from the last treatment unit in the Nth-level sewage treatment pool enters the sewage pump through the sludge discharge pipe, part of the sludge is mixed with the sewage from the upper sewage treatment unit flowing into the sewage pump, and then flows into the water distribution system through the mud-water mixing inlet pipe; the other part of the sludge is discharged through the sludge discharge pipe on the sewage pump.

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