Device and method for rapidly culturing aerobic granular sludge and treating low-carbon-ratio municipal sewage
Technical Field
The invention relates to a device and a method for quickly culturing aerobic granular sludge and treating low-carbon-nitrogen-ratio urban sewage, belonging to the field of biological sewage treatment.
Background
As a novel sewage biological treatment technology with great application potential, compared with the traditional activated sludge method, the aerobic granular sludge has the advantages of compact physical structure, excellent settling property, large biological retention, functional flora coupling and the like, has obvious technical advantages in the aspects of improving sludge-water separation, strengthening decontamination performance, reducing engineering investment and the like, is expected to solve the problems of unstable effluent quality, high operation energy consumption, larger occupied area and the like of the existing sewage biological treatment process, and provides a new mode for upgrading and modifying of urban sewage treatment plants. However, for the water quality characteristics of low C/N in China, the main bottlenecks of the engineering application of the technology at present are that the aerobic granular sludge granulation time is slow, the structure is easy to destabilize, and the operation is limited.
Many researchers have fast granulation time of granular sludge cultured by high C/N, but the granules are loose and easy to swell and disintegrate, and cannot stably run for a long time. Meanwhile, the economic and efficient realization of nitrogen and phosphorus removal of low C/N ratio municipal sewage has many difficulties: further improving the effluent quality, fully utilizing the carbon source of the raw water, contradicting various functional bacteria in the sludge age, competing the functional bacteria for dissolved oxygen and the like.
Therefore, research and development of an efficient and energy-saving synchronous nitrogen and phosphorus removal process suitable for low C/N ratio municipal sewage are urgently needed. According to the invention, by adopting an anaerobic/aerobic/anoxic operation mode, glycan bacteria, phosphorus accumulating bacteria, ammonia oxidizing bacteria, nitrite oxidizing bacteria, denitrifying phosphorus accumulating bacteria and denitrifying glycan bacteria which grow slowly are screened, and under the condition of higher water conservancy shearing force generated by high aeration speed of an aerobic section through medium-speed stirring in an anaerobic section and an anoxic section, stable aerobic granular sludge is quickly formed under the condition of continuously shortening the settling time and increasing hydraulic selective pressure. An anaerobic section: PAOs and GAOs convert volatile fatty acids in water which are easily utilized by microorganisms into internal carbon source substances stored in cells, and PAOs is accompanied with phosphorus release phenomenon; an aerobic section: due to the micro-ecological environment of AGS, AOB, NOB, PAOs, DNPAOs and DNGAOs cooperate to carry out synchronous nitrification and excessive phosphorus absorption; an anoxic section: DNPAOs and DNGAOs utilize the residual nitrite and nitrate nitrogen in the aerobic section as electron acceptors to perform denitrification dephosphorization and endogenous denitrification, and finally achieve deep denitrification dephosphorization in sewage.
Disclosure of Invention
The invention aims to provide a device and a method for quickly culturing aerobic granular sludge and treating low-carbon-ratio urban sewage, which realize efficient and energy-saving synchronous nitrogen and phosphorus removal of the low-carbon-nitrogen-ratio urban sewage based on the aerobic granular sludge cultured under the combined regulation and control of selected slow-growing microorganisms and hydraulic selective pressure, solve the problems of insufficient carbon source, poor phosphorus removal effect, incapability of achieving the optimal effect of nitrogen and phosphorus removal under the same condition and the like in the traditional nitrogen and phosphorus removal process, have simple process flow, save aeration quantity and reduce operation cost. The stability of system operation can be effectively maintained.
The purpose of the invention is solved based on the following technical scheme:
the utility model provides a device of quick cultivation aerobic granule mud and processing low carbon ratio municipal sewage which characterized in that includes: the system comprises a domestic sewage inlet water bucket (1), a water inlet peristaltic pump (2), a synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3), an online automatic control system (4) and an outlet water bucket (5);
an interlayer with a water area temperature control is arranged on the outer surface of the AGSBR reactor (3) main body for synchronously nitrifying and internally denitrifying and dephosphorizing, and the lower part of the interlayer with the water area temperature control is connected with a constant temperature water bath water return valve (3.9) at the upper part of the interlayer with the water area temperature control through a constant temperature water bath water outlet valve (3.6) in sequence via a constant temperature water bath peristaltic pump (3.7) and a low temperature constant temperature bath (3.8);
the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) is cylindrical, the height-diameter ratio is 20, for example, the height is 1.7m, the inner diameter is 8cm, and the effective volume is 8L. The high height-diameter ratio (H/D is 20) provided by the reactor is combined with high aeration rate in the aerobic section, so that the granular sludge has a long enough hydraulic flow state in the reactor, and the granulation of the sludge is facilitated; the AGSBR reactor (3) for synchronously nitrifying and dephosphorizing the endogenous denitrification phosphorus is provided with a digital display constant speed stirrer (3.2), a pH probe (3.13) and a DO probe (3.14), wherein the pH probe (3.13) and the DO probe (3.14) are connected with a pH and DO tester (3.12); the sampling ports (3.10) are arranged at different positions of the upper part and the lower part of the side surface of the AGSBR reactor (3) for synchronously nitrifying the endogenous denitrifying phosphorus removal; an aeration disc (3.3) is arranged at the bottom in the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3), and an aeration pump (3.4) is connected with the aeration disc (3.3) through a gas flowmeter (3.5);
the online automatic control system (4) comprises a computer (4.1) and an online automatic controller (4.2); the computer (4.1) is connected with the on-line automatic controller (4.2), the on-line automatic controller (4.2) is respectively connected with the digital display constant speed stirrer (3.2) and the pH and DO measuring instrument (3.12), and the on-line automatic controller (4.2) is also connected with the aeration pump (3.4), the water inlet peristaltic pump (2) and the electromagnetic valve (3.11);
the domestic sewage inlet water bucket (1) is connected with a built-in water inlet valve (3.1) at the lower part of the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) through a water inlet peristaltic pump (2), and a water outlet at the middle part of the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) is connected with an outlet water bucket (5) through an electromagnetic valve (3.11).
Further, the on-line automatic controller (4.2) comprises an aeration pump relay (4.3), an electromagnetic valve relay (4.4), a water inlet peristaltic pump relay (4.5), a stirrer relay (4.6) and a data signal interface (4.7) of a pH and DO measuring instrument; aeration pump relay (4.3) is connected with aeration pump (3.4) correspondingly, solenoid valve relay (4.4) is connected with solenoid valve (3.11) correspondingly, intake peristaltic pump relay (4.5) is connected with intake peristaltic pump (2) correspondingly, agitator relay (4.6) is connected with digital display constant speed agitator (3.2) correspondingly, pH, DO apparatus data signal interface (4.7) is connected with pH, DO apparatus (3.12) correspondingly.
The online automatic controller (4.2) is in data connection with the computer (4.1) through a network by utilizing a built-in 4G card, and further controls the parameter setting.
Sludge particles are arranged in the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3).
The sewage treatment process in the device comprises the following steps: after the domestic sewage enters a synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3), medium-speed anaerobic stirring is firstly carried out, laboratory experiments show that a lower stirring speed (less than 50r/min) cannot provide enough hydraulic shearing force to enable the sludge to be rapidly granulated and is not beneficial to the sufficient contact of the sludge and the sewage, a higher stirring speed (more than 200r/min) can enable the sludge to be continuously in a floc state and cannot be granulated, then PAOs carries out anaerobic phosphorus release, the PAOs and the GAOs convert volatile fatty acid which is easy to be utilized by microorganisms in the water into an internal carbon source substance PHAs stored in cells, and along with the decomposition of glycogen, denitrifying bacteria use enough carbon sources to denitrify the residual nitrite and nitrate in the previous period; then, carrying out an aerobic state, wherein PAOs arranged on the outer layer of the particles use dissolved oxygen as an electron acceptor, excessive aerobic phosphorus absorption is carried out by utilizing an internal carbon source stored in an anaerobic section, AOB and NOB complete nitration reaction, ammonia nitrogen is converted into nitrite and nitrate, DNPAOs and DNGAOs arranged on the inner layer of the particles use a carbon source stored in cells to carry out denitrification phosphorus removal and endogenous denitrification so as to convert the nitrite and the nitrate into nitrogen, the aeration amount of the aerobic section is larger, the provided water conservancy shearing force is also larger, and a good water conservancy condition is provided for the formation of aerobic granular sludge; in the anoxic stage, PAOs consume the residual dissolved oxygen in the reactor to absorb phosphorus, DNPAOs utilize the carbon source stored in the cells to accumulate orthophosphate in the water into the cells by taking nitrite and nitrate as electron acceptors, and DNGAOs also utilize the carbon source stored in the cells to carry out endogenous denitrification by taking nitrite and nitrate as electron acceptors so as to convert the carbon source into nitrogen; and finally, carrying out precipitation drainage.
The invention also provides a method for rapidly culturing aerobic granular sludge and treating low-carbon-ratio urban sewage, which comprises the following steps:
1) water is fed into the water inlet barrel:
and (3) a granular sludge culture period: running a synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) at 25 ℃, adopting municipal sewage with high C/N ratio, feeding water with COD of 459.6-645 mg/L, TN concentration of 43-79 mg/L, TP concentration of 4-9 mg/L and pH value of 6.8-7.4;
the stable operation period of the process: running a synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) at 25 ℃, adopting municipal sewage with low C/N ratio, feeding water with COD (chemical oxygen demand) of 165.5-358.1 mg/L, TN (total nitrogen) concentration of 50.5-65.05 mg/L, TP (total phosphorus) concentration of 4-9 mg/L and pH value of 6.8-7.4;
2) sludge inoculation: the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) is inoculated with sludge from the return sludge of the secondary sedimentation tank of the sewage plant; adding the retrieved sludge into domestic sewage for smoldering for 1-2 days, taking a certain amount of smoldered sludge for inoculation, and after inoculation, synchronously nitrifying the sludge concentration in an endogenous denitrification dephosphorization AGSBR reactor (3) to be 3000-3500 mg/L, wherein the average grain size of the inoculated sludge is 52.78 microns;
3) culturing aerobic granular sludge: the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) runs for 4 periods every day, and each period is 6 hours; the method specifically comprises the following steps: the method comprises the following steps that (1) inflow water of a high C/N sewage inflow water barrel (1) firstly enters a synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) through an inflow peristaltic pump (2) and an inflow valve (3.1), and meanwhile, a stirrer (3.2) is started to carry out anaerobic stirring for 2 hours at the speed of 100 plus one year (120 r/min), so that a certain water shearing force is provided by stirring action to facilitate sludge granulation, sludge can be fully contacted with COD (chemical oxygen demand) in water, and internal carbon source storage is enhanced; then starting an aeration pump (3.4) to carry out aerobic aeration for 2 hours, controlling the flow rate of aeration to be more than 3L/min through a gas flowmeter (3.5), controlling the hydraulic shearing force to be more than 1.2cm/s and controlling the dissolved oxygen to be 7-9 mg/L; then 100 and 120r/min anoxic stirring is carried out for 95-113 min; then 20-2 min of precipitation is carried out, water is drained for 3min through an electromagnetic valve (3.11), and 2min is left unused, wherein the drainage ratio is 50%; in addition, the settling time is shortened by 1 minute every 6 cycles until the settling time is 2min, and hydraulic selective pressure can be formed by continuously shortening the settling time to elutriate the sludge with poor settling property and screen the sludge with good settling property; the reactor adopts an anaerobic/aerobic/anoxic operation mode, enriches slow-growing functional bacteria, is beneficial to densification of a particle structure, forms smaller particles, and shows relatively higher stability in the aspects of specific gravity, sedimentation performance and cell hydrophobicity. During the culture period, special sludge discharge is not carried out, and the sludge concentration in the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) is maintained within the range of 3000-5000 mg/L;
4) the stable operation of the synchronous nitrification endogenous denitrification dephosphorization process: the process adopts an anaerobic/aerobic/anoxic operation mode and aims to strengthen the storage effect of an internal carbon source of the polyphosphate accumulating bacteria and the glycan bacteria in the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3); the reactor was operated for 4 cycles per day, each cycle being 6 hours; the method specifically comprises the following steps: the inflow water of the low C/N sewage inflow water barrel (1) firstly enters the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) through the inflow pump (2) and the inflow valve (3.1), and simultaneously the stirrer (3.2) is started to carry out anaerobic stirring for 2 hours at the speed of 140 plus one year and 160r/min, so that the sludge can be fully contacted with COD in the water under the stirring action, and the storage of an internal carbon source is enhanced; then starting an aeration pump (3.4) to carry out aerobic aeration for 2 hours, controlling the flow rate of aeration to be below 0.8L/min through a gas flowmeter (3.5), controlling the hydraulic shearing force to be less than 0.03cm/s and controlling the dissolved oxygen to be below 3mg/L, wherein the lower dissolved oxygen can increase the nitrogen loss of an aerobic section and improve the denitrification efficiency; then 140 plus 160r/min anoxic stirring is carried out for 113min, the stirring speed in the process stabilization period is higher than that in the culture period, because the aeration quantity in the process stabilization period is reduced, the hydraulic shearing force generated in the aerobic section is smaller, and the anaerobic section and the anoxic section improve the stirring speed to maintain a higher hydraulic shearing force, which is favorable for the stable operation of the aerobic granular sludge; the next 2min of precipitation, 3min of water drainage through the solenoid valve (3.11), and 2min of idle, the drainage ratio is 50%; the sludge concentration in the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) is maintained within the range of 3000-5000 mg/L;
after the system is started for 25 days, the floc sludge is completely granulated, and the average particle size of the mature granular sludge is 600-700 mu m. The effluent water reaches the first grade A standard in the whole operation process.
The device and the method for quickly culturing aerobic granular sludge and treating low-carbon-ratio urban sewage have the following advantages:
1) the selection of the slow-growing microorganism is beneficial to the densification of the particle structure, the particle size of the formed particles is small, the average particle size is 600-700 mu m, and the particles show relatively high stability in the aspects of specific gravity, sedimentation performance and cell hydrophobicity. The high height-diameter ratio (H/D ═ 20) provided by the reactor is combined with high aeration rate in the aerobic section to enable the granular sludge to have a sufficiently long hydraulic flow state in the reactor, and then is combined with high hydraulic shearing force generated by medium-speed stirring in the anaerobic and anoxic section and hydraulic selective pressure generated by continuously shortening the sedimentation time to realize rapid granulation of the sludge, so that main functional floras (PAOs, GAOs, DNPAOs, DNGAOs, AOB) are enriched, the decontamination effect is stronger, the amount of the generated sludge is less, the reduction of residual sludge is facilitated, and the energy consumption and resources are saved.
2) The synchronous nitrification endogenous denitrification dephosphorization process comprises the processes of internal storage of an anaerobic section, anaerobic phosphorus release, aerobic phosphorus absorption, synchronous nitrification endogenous denitrification, denitrification dephosphorization and the like. On the basis of fully utilizing and storing the organic carbon source of the raw water, the process improves the denitrification efficiency by synchronously nitrifying the internal source denitrification through the aerobic granular sludge, avoids the addition of the external carbon source and ensures the quality of the effluent water through the post-internal source denitrification. Therefore, the process can effectively reduce the oxygen consumption and the energy consumption in the municipal sewage treatment process.
Drawings
FIG. 1 is a schematic structural view of an apparatus for rapidly culturing aerobic granular sludge and treating low carbon ratio municipal sewage according to the present invention.
In the figure, 1 is a domestic sewage inlet bucket, 2 is an inlet peristaltic pump, 3 is a synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor, 4 is an online automatic control system, and 5 is an outlet bucket; 3.1 is a water inlet valve, 3.2 is a digital display constant speed stirrer, 3.3 is an aeration disc, 3.4 is an aeration pump, 3.5 is a gas flowmeter, 3.6 is a constant temperature water bath water outlet valve, 3.7 is a constant temperature water bath peristaltic pump, 3.8 is a low temperature constant temperature tank, 3.9 is a constant temperature water bath water return valve, 3.10 is a sampling port, 3.11 is an electromagnetic valve, 3.12 is a pH and DO determinator, 3.13 is a pH probe, and 3.14 is a DO probe; 4.1 is a computer, 4.2 is an online automatic controller, 4.3 is an aeration pump relay, 4.4 is an electromagnetic valve relay, 4.5 is a water inlet peristaltic pump relay, 4.6 is a stirrer relay, and 4.7 is a data signal interface of a pH and DO measuring instrument.
FIG. 2 is a-e are morphology diagrams corresponding to aerobic granular sludge at days 0, 5, 29, 38 and 42, respectively, and f-k are scanning electron micrographs of mature aerobic granular sludge.
FIG. 3 is a graph of contaminant removal data during reactor operation; a (COD), b (NH)4 +-N)、c(PO4 3--P)、d(TN)。
Detailed Description
The invention will be further described with reference to the following figures and examples, but the invention is not limited to the following examples.
Example 1
As shown in figure 1, the device and the method for rapidly culturing aerobic granular sludge and treating low-carbon-ratio municipal sewage mainly comprise a domestic sewage inlet water bucket (1), an inlet water peristaltic pump (2), a synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3), an online automatic control system (4) and an outlet water bucket (5); wherein the domestic sewage inlet water bucket (1) is connected with the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) through an inlet water peristaltic pump (2), and the outlet water bucket (5) is connected with the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) through an electromagnetic valve (3.11);
the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) is cylindrical, the height is 1.7m, the inner diameter is 8cm, the height-diameter ratio is 20, and the effective volume is 8L. A water inlet valve (3.1), a digital display constant speed stirrer (3.2), an aeration disc (3.3), an aeration pump (3.4), a gas flowmeter (3.5), a constant temperature water bath water outlet valve (3.6), a constant temperature water bath peristaltic pump (3.7), a low temperature constant temperature tank (3.8), a constant temperature water bath water return valve (3.9), a sampling port (3.10), an electromagnetic valve (3.11), a pH and DO determinator (3.12), a pH probe (3.13) and a DO probe (3.14) are arranged in the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3);
the online automatic control system (4) comprises a computer (4.1) and an online automatic controller (4.2); the on-line automatic controller (4.2) comprises an aeration pump relay (4.3), an electromagnetic valve relay (4.4), a water inlet peristaltic pump relay (4.5), a stirrer relay (4.6) and a data signal interface (4.7) of a pH and DO measuring instrument; the online automatic controller (4.2) is in data connection with the computer (4.1) through a network by utilizing a built-in 4G card, and further controls the parameter setting.
Method for applying the device according to claim 1, characterized in that it comprises the following steps:
1) water is fed into the water inlet barrel:
and (3) a granular sludge culture period: running a synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) at 25 ℃, wherein the municipal sewage with high C/N ratio has the influent COD of 459.6-645 mg/L, the TN concentration of 43-79 mg/L, the TP concentration of 4-9 mg/L and the pH value of 6.8-7.4;
the stable operation period of the process: running a synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) at 25 ℃, wherein the low C/N ratio municipal sewage has influent COD of 165.5-358.1 mg/L, TN concentration of 50.5-65.05 mg/L, TP concentration of 4-9 mg/L and pH value of 6.8-7.4;
2) sludge inoculation: the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) is inoculated with sludge from the return sludge of the secondary sedimentation tank of the sewage plant; adding the retrieved sludge into domestic sewage for smoldering for 1-2 days, taking a certain amount of smoldered sludge for inoculation, and after inoculation, synchronously nitrifying the sludge concentration in an endogenous denitrification dephosphorization AGSBR reactor (3) to be 3000-3500 mg/L, wherein the average grain size of the inoculated sludge is 52.78 microns;
3) culturing aerobic granular sludge: the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) runs for 4 periods every day, and each period is 6 hours; the method specifically comprises the following steps: the method comprises the following steps that (1) inflow water of a high C/N sewage inflow water barrel (1) firstly enters a synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) through an inflow peristaltic pump (2) and an inflow valve (3.1), and meanwhile, a stirrer (3.2) is started to carry out anaerobic stirring for 2 hours at the speed of 100 plus one year (120 r/min), so that a certain water shearing force is provided by stirring action to facilitate sludge granulation, sludge can be fully contacted with COD (chemical oxygen demand) in water, and internal carbon source storage is enhanced; then starting an aeration pump (3.4) to carry out aerobic aeration for 2 hours, controlling the flow rate of aeration to be more than 3L/min through a gas flowmeter (3.5), controlling the hydraulic shearing force to be more than 1.2cm/s and controlling the dissolved oxygen to be 7-9 mg/L; then 100 and 120r/min anoxic stirring is carried out for 95-113 min; then 20-2 min of precipitation is carried out, water is drained for 3min through an electromagnetic valve (3.11), and 2min is left unused, wherein the drainage ratio is 50%; in addition, the settling time is shortened by 1 minute every 6 cycles until the settling time is 2min, and hydraulic selective pressure can be formed by continuously shortening the settling time to elutriate the sludge with poor settling property and screen the sludge with good settling property; the reactor adopts an anaerobic/aerobic/anoxic operation mode, enriches slow-growing functional bacteria, is beneficial to densification of a particle structure, forms smaller particles, and shows relatively higher stability in the aspects of specific gravity, sedimentation performance and cell hydrophobicity. During the culture period, special sludge discharge is not carried out, and the sludge concentration in the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) is maintained within the range of 3000-5000 mg/L;
4) the stable operation of the synchronous nitrification endogenous denitrification dephosphorization process: the process adopts an anaerobic/aerobic/anoxic operation mode and aims to strengthen the storage effect of an internal carbon source of the polyphosphate accumulating bacteria and the glycan bacteria in the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3); the reactor was operated for 4 cycles per day, each cycle being 6 hours; the method specifically comprises the following steps: the inflow water of the low C/N sewage inflow water barrel (1) firstly enters the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) through the inflow pump (2) and the inflow valve (3.1), and simultaneously the stirrer (3.2) is started to carry out anaerobic stirring for 2 hours at the speed of 140 plus one year and 160r/min, so that the sludge can be fully contacted with COD in the water under the stirring action, and the storage of an internal carbon source is enhanced; then starting an aeration pump (3.4) to carry out aerobic aeration for 2 hours, controlling the flow rate of aeration to be below 0.8L/min through a gas flowmeter (3.5), controlling the hydraulic shearing force to be less than 0.03cm/s and controlling the dissolved oxygen to be below 3mg/L, wherein the lower dissolved oxygen can increase the nitrogen loss of an aerobic section and improve the denitrification efficiency; then stirring for 113min under oxygen deficiency at 140-160 r/min; the next 2min of precipitation, 3min of water drainage through the solenoid valve (3.11), and 2min of idle, the drainage ratio is 50%; the sludge concentration in the synchronous nitrification endogenous denitrification dephosphorization AGSBR reactor (3) is maintained within the range of 3000-5000 mg/L;
after the system is started for 25 days, the floc sludge is completely granulated, and the average particle size of the mature granular sludge is 600-700 mu m. FIG. 2 shows a morphology chart of aerobic granular sludge granulation stage and an electron microscope image after maturation. The effluent reached the first class a standard throughout the run, as shown in fig. 3, which is a data graph of contaminant removal at the entire stage of the invention.