Method for regranulating aerobic granular sludge

Abstract

The present application relates to the technical field of biological sewage treatment, and particularly relates to a method for regranulation of aerobic granular sludge. The method for regranulation of aerobic granular sludge provided by the present application uses aged aerobic granular sludge as seed sludge, first performs crushing treatment on the seed sludge, then uses the crushed seed sludge as a microbial growth and adhesion body to perform domestication culture, and further combines with low-intensity ultrasonic stimulation, so as to accelerate the granulation process of the granular sludge and effectively improve the denitrification and phosphorus removal performance of the granular sludge. The above method provided by the present application not only provides a new idea and a new strategy for the resource utilization of aged large-particle aerobic granular sludge, but also shortens the formation period of the granular sludge, makes the sludge granulate rapidly and successfully, solves the bottleneck problems of sludge granulation and large-particle sludge disintegration, and is very beneficial to promoting the industrial application process of the aerobic granular sludge.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biological sewage treatment, and particularly relates to a method for regranulation of aerobic granular sludge. BACKGROUND

[0002] Aerobic granular sludge (AGS) has a compact structure, excellent settling characteristics, diverse microbial populations, and high nutrient removal capacity, and is widely considered to be the most promising biological wastewater treatment technology. Aerobic granular sludge can degrade organic matter into inorganic matter under aerobic conditions through bacterial metabolism, and remove nitrogen and phosphorus pollution, thereby achieving wastewater purification, and having great advantages in effectively reducing carbon emissions and resource utilization. Sewage plants can rely on this technology to complete the technical iteration of existing traditional activated sludge processes. At present, AGS systems have been implemented in dozens of wastewater treatment plants (WWTPs) around the world, such as the Nereda® process operated by Royal HaskoningDHV. However, the long granulation startup time of granular sludge and the collapse of granular sludge systems after a long time of operation are still key bottlenecks that hinder the implementation of AGS technology worldwide.

[0003] Shortening the startup period of aerobic granular sludge is one of the keys to promoting its widespread application. According to research reports, cultivating aerobic granular sludge from activated sludge is a slow process: in full-scale wastewater treatment plants, the startup period of activated sludge granulation is as long as several months. The long startup period increases equipment occupancy, energy consumption, and labor costs. In order to accelerate granulation and improve the stability of AGS, scholars have conducted a large number of studies. Researchers have proposed four strategies to accelerate the formation of aerobic granular sludge: (1) adding metal ions: metal ions can directly potentially affect bacterial adhesion by affecting electrostatic interactions. At appropriate concentrations, Ca 2+ (10-80mg / L), Mg 2+ (0-20mg / L) and K + (20-80mg / L) can enhance microbial adhesion and accelerate granulation; (2) adding carriers or flocculants, such as porous material carriers with adsorption capacity, such as granular activated carbon and biochar, can increase the effective collision between co-polymers, thereby promoting the growth of granules; (3) changing the inoculated sludge: anaerobic granular sludge or crushed granules can be used as the attachment core of flocculation granules to maintain a large biomass during the granulation process to accelerate the formation of aerobic granules and complete granulation; (4) inoculation of special strains: by selecting strains with high cell surface hydrophobicity and microorganisms with rapid aggregation ability, the granulation time of microbial granules can be shortened.

[0004] Although the above four methods can accelerate granulation, these methods also have some obvious shortcomings. For example: the continuous addition of metal ions will increase the cost of reagents and sludge treatment, and will introduce foreign substances, accelerate the production of calcified granular sludge, and is not suitable for large-scale application, and will have a negative impact on subsequent advanced treatment; while the addition of carriers or flocculants can easily cause secondary pollution, increase the cost of sludge treatment, and the granules formed by this method do not belong to the traditional concept of granular sludge, but are similar to the biofilm on the suspended carrier. In addition, the above-mentioned methods involving changing the inoculated sludge and adding special strains are not suitable for large-scale promotion due to the scarcity and high transportation cost of these two types of sludge.

[0005] In addition to the long start-up period of aerobic granular sludge, the industrialization of aerobic granular sludge also faces the problem of easy disintegration after a long time of operation. This is mainly because as the system runs, the particle size of aerobic granular sludge will change continuously, and the stability of the sludge will also fluctuate. As an important indicator of granular sludge, particle size affects the mass transfer effect between different structures within the granule. When the particle size of granular sludge is 1-2 mm, the granular sludge often has better mass transfer efficiency and larger specific surface area, and the microbial activity within the granule is higher; while aerobic granular sludge larger than 3 mm has a large internal space that can couple multiple bacterial populations, but when mineral accumulation and granule size further increase, causing the mass transfer channel to be blocked, the diffusion limitation of oxygen and nutrients will cause the outer layer of microorganisms to consume a large amount of nutrients, and the metabolic activity of the inner layer of cells will deteriorate, thus causing the granule to disintegrate under the action of shear force, and the system to collapse. Researchers have found that when the particle size is >4 mm, the granular sludge cannot withstand the external shear force and the bacterial richness and diversity within the granule will decrease as the particle size increases.

[0006] However, the existence of large-particle-size granular sludge is not just disintegration: this large granular sludge often contains a large amount of metal ions such as calcium, iron, and a large amount of nitrogen and phosphorus nutrients absorbed and assimilated during long-term operation; not only that, it also contains a large amount of high-value substances such as proteins, polysaccharides, and humic acid. If large-particle-size granular sludge can be recycled, it can also increase the overall value of the aerobic granular sludge system while recycling energy in a rational manner.

[0007] The current state of the art has reported a number of related methods for accelerating the granulation of aerobic granular sludge, but there are few related studies on the resource utilization of large-particle-size granular sludge. In addition to the certain shortcomings of the above granulation methods, the current state of the art has not been able to solve the problems of granular sludge stability and resource utilization after system disintegration. In order to promote the industrialization process of aerobic granular sludge, it is currently urgent to propose effective strategies to shorten the formation period of granular sludge, make the sludge granulate quickly, and find a way to resourcefully utilize large-particle-size granular sludge.

[0008] Therefore, a new granulation technology of granular sludge is developed, so as to solve the two technical bottlenecks of granulation and disintegration at one time, not only can realize the rationalization of energy reuse, but also can increase the overall value of aerobic granular sludge, and promote the industrialization process of granular sludge. SUMMARY

[0009] In view of the deficiencies of the prior art, the main purpose of the present application is to provide a method for re-granulating aerobic granular sludge, which can not only realize the reuse of aged aerobic granular sludge, but also accelerate the granulation process of granular sludge and enhance the denitrification and phosphorus removal performance of granular sludge.

[0010] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0011] A method for re-granulating aged aerobic granular sludge, comprising the following steps:

[0012] (1) Taking the aged aerobic granular sludge as seed sludge, crushing the seed sludge, and then inoculating the crushed seed sludge into an SBR reactor for acclimation culture; wherein the particle size of the aged aerobic granular sludge is 3-6 mm; the concentration of the inoculated seed sludge is 2-4 g / L during the acclimation culture;

[0013] (2) After 2-3 days of acclimation culture, all the sludge is taken out from the SBR reactor, and after adjusting the sludge concentration, ultrasonic treatment is carried out, the ultrasonic intensity is 0.1-0.2 W / mL, the ultrasonic time is 3-10 min, and after the ultrasonic treatment is completed, the sludge is transferred to the SBR reactor for continuous acclimation culture; then every 2-3 days is an ultrasonic cycle, and the ultrasonic treatment step is repeated;

[0014] (3) After acclimation culture for 14-20 days, the acclimation culture is stopped, and the re-granulated aerobic granular sludge is obtained.

[0015] Further preferably, the crushing is carried out by physical crushing.

[0016] Further preferably, the average particle size of the crushed seed sludge is 0.15-0.30 mm.

[0017] The structure of the SBR reactor used for sludge culture is not particularly limited in the present application, and the skilled person can use conventional reactor types in the field. Further preferably, the height-diameter ratio of the SBR reactor is (4-10):1.

[0018] Further preferably, the acclimation culture is carried out by the way of bottom water inlet and middle water outlet.

[0019] Further preferably, the pH of the influent is 7.0-8.5, and the influent is natural wastewater or artificial wastewater.

[0020] Further preferably, the COD concentration in the influent is 800-1000 mg / L, the NH4 + concentration is 20-60 mg / L, and the PO4 3- concentration is 5-20 mg / L.

[0021] Further preferably, during the domestication culture, the dissolved oxygen concentration in the SBR reactor is 2-10 mg / L, and the temperature is 20-35 DEG C.

[0022] Further preferably, in step (2), the sludge concentration is adjusted to 3-5 g / L by using pure water.

[0023] Further preferably, in step (3), the average particle size of the obtained aerobic granular sludge after the regranulation is 0.8-2 mm.

[0024] The above technical scheme of the present application has the following beneficial effects:

[0025] The method for regranulating aged aerobic granular sludge provided by the present application uses the aged aerobic granular sludge as seed sludge, first performs a crushing treatment on the seed sludge, then uses the crushed seed sludge as a microbial growth and attachment body to perform a domestication culture, and further combines a low-intensity ultrasonic stimulation, thereby accelerating the granulation process of the granular sludge and effectively improving the denitrification and phosphorus removal performance of the granular sludge.

[0026] In the present application, the aged aerobic granular sludge after application is used as seed sludge, and the most obvious feature of the aged aerobic granular sludge is an increased particle size, which leads to a reduced wastewater treatment performance and a deteriorated application performance. However, the aged aerobic granular sludge is essentially a microbial aggregate, and contains more proteins, polysaccharides and other substances than the original seed sludge inoculated by ordinary granulation, and also contains a large amount of metal ions such as iron and calcium. These substances can accelerate the granulation process in the initial granulation stage, and there is no need to add exogenous substances such as metal ions, carriers or flocculants, which is conducive to reducing the granulation cost. Moreover, the aged large-particle aerobic granular sludge is essentially a carrier for microbial attachment, and contains a variety of microorganisms. Therefore, the crushed aerobic granular sludge used in the present application is conducive to maintaining a large biomass during the sludge granulation process, and is rich in safe microbial strains with high cell aggregation ability, thereby shortening the time for the formation of microbial granules. In particular, after the crushed aerobic granular sludge is used as seed sludge, the present application further couples a low-intensity ultrasonic wave, which provides sufficient shear stress, changes the sludge aggregation ability, affects the mass transfer channel, stimulates the microbial activity, and the like, thereby effectively coupling with the inoculated granular sludge to jointly accelerate the granulation process.

[0027] Therefore, the above method provided by the present application can not only provide a new idea and a new strategy for the resource utilization of the aged aerobic granular sludge, but also shorten the formation period of the granular sludge, make the aged granular sludge granulate successfully quickly, synchronously solve the bottleneck problems of sludge granulation and large-particle-size sludge disintegration, and be very beneficial to promoting the industrial application process of the aerobic granular sludge. DETAILED DESCRIPTION

[0028] The technical solutions of the present application are further described below in combination with specific embodiments, but the present application is not limited to the scope of the described embodiments. In the following examples, the used methods are all conventional methods in the art unless otherwise specified. In the following examples, the used materials are all conventional materials in the art unless otherwise specified, and can be obtained from conventional channels.

[0029] In the following examples of the present application, the aged aerobic granular sludge is cultured from anaerobic granular sludge as the original seed sludge. The anaerobic granular sludge (original seed sludge) is from a sewage treatment plant in Zhengzhou, and nutrients are added to the influent to maintain the activity of microorganisms during the cultivation process. After a long time of water flow and aeration cultivation, the aerobic granular sludge with increased particle size and aging is obtained under the action of shear force. The nutrient content in the influent used in the cultivation of the anaerobic granular sludge is COD 1000 mg / L, ammonia nitrogen (NH4 + ) 50 mg / L, and phosphorus (PO4 3- ) 10 mg / L.

[0030] In the following examples of the present application, SS and VSS are unit indexes frequently used in sludge systems. SS is the abbreviation of MLSS, which represents the suspended matter content in the activated sludge; and VSS represents the organic matter content in the sludge. EXAMPLE

[0031] This embodiment 1 provides a method for re-granulating the aged aerobic granular sludge, which comprises the following steps:

[0032] (1) Selecting the aged aerobic granular sludge with a particle size of 5-6 mm (sludge cultivation time 300 days) as the seed sludge;

[0033] It is tested that the particle size of the above aerobic granular sludge before aging is 2-3 mm, and the removal rates of nitrogen (NH4 + ) and phosphorus (PO4 3- ) are both above 95%. After aging, the particle size of the aerobic granular sludge is increased to 5-6 mm, and the removal rates of ammonia nitrogen (NH4 + ) and phosphorus (PO4 3-The removal rates were 70.29% and 40.13%, respectively. After aging, the particle size of the sludge increased significantly compared to that before aging, and the performance decreased significantly. Further testing showed that in the above-mentioned aged aerobic granular sludge: the calcium content was 15 mg / g SS, the iron content was 11 mg / g SS, the total phosphorus content was 12.33 mg / g VSS, of which the inorganic phosphorus content accounted for 68.37%, and the extracellular polymeric substance content was 79.3 mg / g VSS.

[0034] (2) The seed sludge obtained in step (1) is crushed by a physical method (grinding rod grinding), and the crushed seed sludge is sieved by a screen to obtain sludge with an average particle size of 0.21 mm. Then the crushed sludge is inoculated into the SBR reactor for acclimation culture, and the volume of the inoculated sludge accounts for 5% of the total volume of the reactor. The sludge concentration after inoculation is 2000 mg / L;

[0035] The process conditions for acclimating and culturing the crushed sludge in the SBR reactor are as follows: the inner diameter of the reactor is 10 cm, the effective height is 40 cm, the effective volume is 1.6 L, the height-diameter ratio is 4:1, the reactor operation cycle is 8 hours, including 30 min of water inflow, 30 min of anaerobic, 165 min of aerobic aeration, 5 min of standing and 10 min of water outflow. The above process is repeated twice every operation cycle, and 3 cycles are operated every day. The water inflow is from the bottom and the water outflow is in the middle, and the volume exchange rate is 50%. The inflow pH is controlled at 7.0-8.5, the inflow uses artificial simulated wastewater, the COD concentration of the inflow is 1000 mg / L, the ammonia nitrogen (NH4 + ) concentration is 50 mg / L, and the phosphorus (PO4 3- ) concentration is 10 mg / L.

[0036] (3) At the end of every 3-day water inflow cycle, all the sludge in the SBR reactor is taken out, the sludge concentration is diluted to 4 g / L by pure water, and then ultrasonic treatment is performed, the ultrasonic intensity is 0.15 W / mL (0.15 W of ultrasonic intensity corresponds to each mL of sludge solution), the ultrasonic time is 4 min, after ultrasonic treatment, the sludge is poured back into the SBR reactor for further acclimation culture, and the ultrasonic treatment cycle is every 3 days. After 15 days of operation, the reactor successfully completes granulation, the sludge concentration (MLSS) reaches 4000 mg / L, and by the 20th day, the average particle size of the granular sludge is strengthened from 0.21 mm at the time of inoculation to 0.93 mm, thus obtaining the aerobic granular sludge after regranulation of Example 1.

[0037] The performance of the aerobic granular sludge after regranulation of Example 1 was tested. Among them, the ammonia nitrogen content test adopts the Nash reagent spectrophotometry method, the phosphorus content test adopts the ammonium molybdate spectrophotometry method, the extracellular polymeric substance is extracted by the hot alkali method and then determined by the Lowery method and the improved phenol-sulfuric acid method, and the ammonia-oxidizing bacteria activity test adopts the method of measuring the ammonia nitrogen concentration degraded by unit mass of sludge per unit time. The test results show that the aerobic granular sludge prepared by Example 1 finally exhibits good denitrification and phosphorus removal performance, and the removal rates of ammonia nitrogen (NH4 + ) and phosphorus (PO4 3- ) are 90.2% and 86.2% respectively. At this time, the extracellular polymeric substance content is 165.45 mg / g VSS, and the ammonia-oxidizing bacteria activity increases by 45.65% compared with before treatment. Therefore, the application significantly improves the application performance of the aged granular sludge by regranulation, and realizes the reuse of the aged granular sludge. Example

[0038] This embodiment 2 provides a method for regranulating aged aerobic granular sludge, which comprises the following steps:

[0039] (1) Selecting aged aerobic granular sludge with a particle size of 4-5 mm (sludge cultivation time 200 days) as seed sludge;

[0040] It is tested that the particle size of the above-mentioned aerobic granular sludge before aging is 1.6-2.2 mm, and the removal rates of ammonia nitrogen (NH4 + ) and phosphorus (PO4 3- ) are both above 90%. The particle size of the aged aerobic granular sludge reaches 4-5 mm, and the removal rates of ammonia nitrogen (NH4 + ) and phosphorus (PO4 3- ) are 75.62% and 70.10% respectively. Further tests show that in the above-mentioned aged aerobic granular sludge: the calcium content is 13 mg / g SS, the iron content is 8 mg / g SS, the total phosphorus content is 15.77 mg / g VSS, and the inorganic phosphorus content accounts for 58.34%, and the extracellular polymeric substance content is 74.9 mg / g VSS.

[0041] (2) The seed sludge is crushed by a physical method (grinding rod grinding), the crushed seed sludge is sieved by a screen mesh to obtain sludge with an average particle size of 0.22 mm, and then the crushed sludge is inoculated in an SBR reactor for acclimation cultivation, the volume of the inoculated sludge accounts for 10% of the total volume of the reactor, and the sludge concentration after inoculation is 2800 mg / L;

[0042] The process conditions for domesticating and culturing the broken sludge in the SBR reactor are as follows: the inner diameter of the reactor is 20 cm, the effective height is 80 cm, the effective volume is 3.2 L, the height-diameter ratio is 4:1, the operation cycle of the reactor is 8 hours, including 25 min of water feeding, 40 min of anaerobic, 160 min of aerobic aeration, 5 min of standing and 10 min of water discharging, the above process is repeated twice every operation cycle, and 3 operation cycles are performed every day. The water is fed from the bottom and discharged in the middle, and the volume exchange rate is 50%. During the operation of the reactor, the dissolved oxygen in the reactor is controlled to be 2.5 mg / L, the temperature is 30 ℃, and the settling time is 3 min. The pH of the influent is controlled to be 7.0-8.5, the influent is artificial simulated wastewater, the COD concentration of the influent is 800 mg / L, the ammonia nitrogen (NH4 + ) concentration is 50 mg / L, and the phosphorus (PO4 3- ) concentration is 10 mg / L.

[0043] (3) At the end of every 3-day water feeding cycle, all the sludge in the SBR reactor is taken out, the sludge concentration is diluted to 4 g / L by pure water, and then ultrasonic treatment is performed, the ultrasonic intensity is 0.15 W / mL, the ultrasonic time is 4 min, after the ultrasonic treatment, the sludge is poured back into the SBR reactor for domestication and cultivation, and the ultrasonic treatment cycle is every 3 days. After 14 days of operation, the reactor successfully completes granulation, the sludge concentration (MLSS) reaches 5600 mg / L, and by the 20th day, the average particle size of the granular sludge is strengthened from 0.22 mm at the time of inoculation to 1.29 mm, thereby obtaining the aerobic granular sludge after regranulation of example 2.

[0044] The performance of the aerobic granular sludge after regranulation of example 2 is tested by the test method of reference example 1. The test results show that the aerobic granular sludge obtained in example 2 exhibits good nitrogen and phosphorus removal performance, and the removal rates of ammonia nitrogen (NH4 + ) and phosphorus (PO4 3- ) are 88.2% and 89.2% respectively. At this time, the content of extracellular polymeric substance is 93.2 mg / g VSS, and the activity of ammonia oxidizing bacteria increases by 40.55% compared with the aged seed sludge. Therefore, it is proved that the application performance of the aged granular sludge is significantly improved by regranulation, and the aged granular sludge is reused.

[0045] Comparative example 1

[0046] The comparative example 1 provides a granulation method of aerobic granular sludge under the action of ultrasound, the preparation method of which is basically the same as that of the example 1, the difference being that in step (3), all the sludge is taken out from the SBR reactor at the end of every 3-day feeding cycle and directly put back into the reactor without ultrasonic treatment, and the rest of the conditions are the same as those of the example 1. After 30 days of operation, the reactor successfully completes granulation, and the MLSS concentration reaches 6000 mg / L. By the 30th day, the average particle size of the granular sludge is strengthened from 0.3 mm at the time of inoculation to 0.804 mm. The granular sludge exhibits good nitrogen and phosphorus removal performance, and the removal rates of ammonia nitrogen (NH4 + ) and phosphorus (PO4 3- ) can reach 80.2% and 73.2%, respectively. It can be seen that if the granular sludge is not treated by ultrasound, the granulation process of the granular sludge will be significantly slowed down, and the nitrogen and phosphorus removal performance of the granular sludge will also be reduced.

[0047] Comparative Example 2

[0048] The comparative example 2 provides a granulation method of activated sludge under the action of ultrasound, the preparation method of which is basically the same as that of the example 1, the difference being that in step (1), activated sludge is directly used as the inoculated sludge, and the activated sludge is from a reactor cultured in the laboratory for 300 days, but no conditions such as shear force for forming the sludge into spheres are provided during the culture process. The average particle size of the activated sludge is 0.088 mm, the culture conditions are that the COD concentration of the influent is 1000 mg / L, the ammonia nitrogen (NH4 + ) concentration is 50 mg / L, and the phosphorus (PO4 3- ) concentration is 10 mg / L. The activated sludge is directly inoculated into the SBR reactor without being broken, and the rest of the steps and conditions are the same as those of the example 1. After 28 days of operation, the reactor completes granulation, and the maximum particle size reaches 0.495 mm. The MLSS concentration in the reactor reaches 5000 mg / L. The granular sludge exhibits good nitrogen and phosphorus removal performance, and the removal rates of ammonia nitrogen (NH4 + ) and phosphorus (PO4 3- ) are 78.2% and 59.1%, respectively. It can be seen that directly domesticating and culturing the activated sludge that has not formed into spheres in combination with ultrasound treatment is not ideal for improving the nitrogen and phosphorus removal performance.

[0049] Comparative Example 3

[0050] The comparative example 3 provides a granulation method of large-particle-size aerobic granular sludge under the action of ultrasound, the preparation method of which is basically the same as that of the example 1, the difference being that in step (3), the granular sludge is treated by ultrasound under the condition of an ultrasonic intensity of 0.5 W / mL, and the rest of the conditions are the same as those of the example 1. After 40 days of operation, the reactor still does not complete granulation, and the MLSS concentration still remains at the original level. The sludge exhibits poor nitrogen and phosphorus removal performance, and the removal rates of ammonia nitrogen (NH4+ ) and phosphorus (PO4 3- ) removal rates were 56.43% and 38.19%, respectively. It can be seen that the use of high-intensity ultrasonic treatment is not conducive to the improvement of the granulation process, and the effect of improving the sludge denitrification and phosphorus removal performance is also limited.

[0051] In summary, the method for re-granulating aged aerobic granular sludge provided by the present application uses aged large-particle aerobic granular sludge as seed sludge, first crushes the seed sludge, then uses the crushed seed sludge as a microbial growth and attachment body for domestication culture, and further combines low-intensity ultrasonic stimulation to accelerate the granulation process of the granular sludge and effectively improve the denitrification and phosphorus removal performance of the granular sludge. The above method provided by the present application not only provides a new idea and strategy for the resource utilization of aged aerobic granular sludge, but also shortens the formation cycle of the granular sludge, makes the sludge granulate quickly, solves the bottleneck problems of sludge granulation and large-particle sludge disintegration, and is very conducive to promoting the industrialization application process of aerobic granular sludge.

[0052] The above is only the preferred embodiment of the present application, and it should be noted that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A method for re-granulating aerobic granular sludge, characterized in that, Includes the following steps: (1) Using aged aerobic granular sludge as seed sludge, the seed sludge is crushed and then inoculated into an SBR reactor for acclimatization and cultivation; wherein, the particle size range of the aged aerobic granular sludge is 3~6mm; and the concentration of the inoculated seed sludge during acclimatization and cultivation is 2~4g / L. (2) After acclimatization and cultivation for 2-3 days, all sludge was removed from the SBR reactor, and the sludge concentration was adjusted before ultrasonic treatment. The ultrasonic intensity was 0.1-0.2 W / mL and the ultrasonic time was 3-10 min. After ultrasonic treatment, the sludge was transferred to the SBR reactor for continued acclimatization and cultivation. Then, every 2-3 days was an ultrasonic cycle, and the ultrasonic treatment steps were repeated. (3) After acclimatization and cultivation for 14 to 20 days, the acclimatization and cultivation were stopped, and aerobic granular sludge after regranulation was obtained.

2. The method for re-granulating aerobic granular sludge according to claim 1, characterized in that, The crushing is performed using physical methods.

3. The method for re-granulating aerobic granular sludge according to claim 1, characterized in that, The average particle size of the crushed seed sludge is 0.15~0.30mm.

4. The method for re-granulating aerobic granular sludge according to claim 1, characterized in that, The height-to-diameter ratio of the SBR reactor is (4~10):

1.

5. The method for regranulating aerobic granular sludge according to any one of claims 1 to 4, characterized in that, The acclimatization and cultivation process uses a bottom-inlet water intake and middle-outlet water drainage method.

6. The method for regranulating aerobic granular sludge according to claim 5, characterized in that, The pH of the influent is 7.0~8.5, and the influent can be natural wastewater or artificial wastewater.

7. The method for re-granulating aerobic granular sludge according to claim 5, characterized in that, The COD concentration in the influent is 800~1000 mg / L, and the NH4+ concentration is... + Concentration of 20~60 mg / L, PO4 3- Concentration 5~20mg / L.

8. The method for re-granulating aerobic granular sludge according to any one of claims 1 to 4, characterized in that, During acclimatization and cultivation, the dissolved oxygen concentration in the SBR reactor is 2~10 mg / L, and the temperature is 20~35℃.

9. The method for re-granulating aerobic granular sludge according to any one of claims 1 to 4, characterized in that, In step (2), the sludge concentration is adjusted to 3~5 g / L using pure water.

10. The method for regranulating aerobic granular sludge according to any one of claims 1 to 4, characterized in that, In step (3), the average particle size of the aerobic granular sludge obtained after regranulation is 0.8~2mm.