Interval aeration sludge single-reflux continuous flow AOA process and device

Abstract

The invention discloses an interval aeration sludge single-reflux continuous flow AOA process and an interval aeration sludge single-reflux continuous flow AOA device, and belongs to the field of biological sewage treatment and recycling. The device comprises a water inlet tank, an interval aeration continuous flow AOA reactor and a secondary sedimentation tank. Raw water is firstly pumped into an anaerobic section of a reactor through a water inlet pump, internal carbon source storage is performed, then the raw water enters an interval aeration section, aeration nitrification is performed in an aerobic section, denitrification is performed by utilizing the stored carbon source in an anoxic section, the raw water enters two aerobic sections and two anoxic sections, and nitrification and internal source denitrification processes are repeated, and a second grid in the section is provided with an anoxic-aerobic alternating grid chamber. According to the method, the carbon source is fully utilized, aerobic and anoxic time is reasonably distributed for interval aeration, internal carbon source loss caused by aeration is reduced, internal source denitrification utilization is promoted, the carbon source adding cost is saved, resource utilization is reasonable, and the development of carbon neutralization in urban sewage treatment is powerfully promoted.

Description

Technical Field

[0001] The present invention relates to an AOA process technology and device for single-return continuous flow of interval aeration sludge, which belongs to the application field of biological treatment of sewage and rationalization of resource consumption reduction. It has the advantages of rationally allocating carbon source utilization of AOA process, reducing internal carbon source waste, deep denitrification and phosphorus removal, reducing raw water carbon source demand and sludge production, and is suitable for technical fields such as urban sewage treatment plants. Background Art

[0002] With the rapid development of society in recent years, the development of urban sewage treatment has been moving closer to high efficiency, greenness and energy saving. The increasing level of emission technology has made it difficult for traditional sewage treatment technology to meet the development needs. Therefore, the development of energy-saving and consumption-reducing environmentally friendly sewage treatment technology has been put on the agenda. Interval aeration divides the original long-distance aerobic section into multiple small sections. While not affecting the nitrification effect, it reduces the internal carbon source loss caused by long-term continuous aeration in the aerobic section. The anoxic cells inserted in the aerobic section of the interval aeration play a role in quickly utilizing the carbon source stored in the cell, which reduces the NO3 produced by nitrification. - Timely denitrification removal can be carried out to minimize carbon source waste; the aerobic switching grid can be flexibly adjusted according to the influent water quality, cleverly dealing with the residual pollutants caused by water quality fluctuations, and removing NH4 in aerobic mode + , ensuring that there is no residual ammonia nitrogen in the effluent, prolonging the overall anoxic hydraulic retention time in the anoxic mode, and assisting in denitrification of NO3 - Multifunctional role of removal.

[0003] Compared with the traditional A 2 Compared with the AOA operation mode, the AOA operation mode moves the aerobic stage forward, eliminating the need for digestion liquid reflux, making full use of the carbon source in the raw water without additional investment, and the operation mode is simpler and more convenient. The AOA operation mode can reduce the additional carbon source addition rate in actual sewage treatment plants by 100%, and the main operating cost expenditure focuses on the power consumption generated by aeration. AOA is different from traditional A 2 There is no significant difference in aeration between the two operating modes. The AOA process stores internal carbon sources in the initial anaerobic stage until denitrification is performed in the anoxic stage. The aerated aerobic stage in between consumes the carbon sources stored in the anaerobic stage, causing a waste of carbon sources and increasing the pressure of endogenous denitrification by denitrification. It is worthwhile to further study the aeration method and aeration pathway of the aerobic stage of the AOA process.

[0004] Interval aeration splits the original long-distance continuous aeration section, splits and advances the original anoxic section at the front and rear ends while ensuring that the overall aerobic time remains unchanged. The unchanged aerobic time ensures that ammonia nitrogen is completely oxidized and removed. At the same time, the short-distance aeration section can reduce the loss of internal carbon sources compared to long-distance continuous aeration, and maximize the utilization rate of internal carbon sources, thereby realizing the redistribution and full utilization of carbon sources in the AOA process. At the same time, due to the difference in the activity of nitrifying bacteria, interval aeration may have a certain promoting effect on the realization of short-range nitrification, and combined with anaerobic ammonia oxidation technology, it has a broad development prospect.

[0005] Therefore, in the process of treating urban sewage with low C / N ratio and large fluctuation of water quality, more carbon source needs to be added, and the effluent NO3 - In order to solve the problems of incomplete removal, slow endogenous denitrification rate, and difficulty in meeting effluent standards when water quality fluctuates, an operation mode of interval aeration in continuous flow is proposed. The functions and appropriate lengths of each functional section are reasonably configured, and the flexibility of water treatment quality is improved by cleverly utilizing the anoxic and anaerobic switching. The process is optimized in the AOA continuous flow process, and efficient, stable and deep denitrification of urban sewage is achieved. Summary of the invention

[0006] Based on the current continuous flow treatment of low C / N domestic sewage with insufficient carbon source and effluent NO3 - In order to solve the problems of incomplete removal, slow endogenous denitrification rate and loss of internal carbon source in aerobic denitrification of AOA process, an interval aerated sludge single recirculation continuous flow AOA process and device were proposed.

[0007] The invention discloses an intermittent aerated sludge single-return continuous flow AOA process and device, which is characterized by comprising an inlet water tank (1), an intermittent aerated continuous flow AOA reactor (2), and a secondary sedimentation tank (3).

[0008] The intermittent aeration continuous flow AOA reactor (2) comprises 15 cells in total, which are divided into three parts along the water flow direction: a front anaerobic section, an intermittent aeration section and an anoxic section, wherein the length ratio of the three sections is 2:6:7, and the alternating ratio of aerobic and anoxic in the intermittent aeration section is 1:1:1, which are aerobic, anoxic and aerobic respectively; the inlet water tank (1) is connected to the first cell (2.1) of the intermittent aeration continuous flow AOA reactor (2) through an inlet pipe (1.1) and an inlet pump (1.2), wherein the first cell (2.1) and the second cell (2.2) are anaerobic cells, and the third cell (2.1) is an anaerobic cell. .3), the fourth cell (2.4) is an aerobic cell, the fifth cell (2.5) and the sixth cell (2.6) are anoxic cells, the seventh cell (2.7) and the eighth cell (2.8) are aerobic cells, the ninth cell (2.9) is anoxic cell, the tenth cell (2.10) is anoxic / aerobic switching cell, the eleventh cell (2.11), the twelfth cell (2.12), the thirteenth cell (2.13), the fourteenth cell (2.14) and the fifteenth cell (2.15) are all anoxic cells, and adjacent cells are connected through water holes (2.18) to prevent back-mixing and short-flow phenomena. The fifteenth cell (2.15) is connected to the secondary sedimentation tank (3) through an outlet pipe (2.17). The sludge in the sludge hopper of the secondary sedimentation tank (3) is returned to the first cell (2.1) through a sludge return pump (3.1) and a return pipe (3.2). This is a single return mode. The remaining sludge in the secondary sedimentation tank is discharged through a remaining sludge pipe (3.3), and the effluent from the secondary sedimentation tank is discharged through an outlet pipe (3.4). The aerobic cells in the aerated aerobic section are all equipped with an aeration pump (2. 19) is connected to the aeration plate (2.19.2) through an aeration pipe (2.19.1) for aeration, and each aeration plate is connected to a rotor flowmeter (2.19.3) to control the aeration volume; the anaerobic section and the anoxic section in the interval aeration continuous flow AOA reactor (2) are equipped with a stirring paddle (2.16) for uninterrupted stirring, and the aerobic grid is equipped with a WTW probe to detect the dissolved oxygen in the aerobic zone, and the aeration volume is regulated by the PLC control system.

[0009] The treatment process of urban sewage in this process is as follows: the urban sewage is pumped from the water inlet tank into the front anaerobic section through the water inlet pump. In the front anaerobic section, the denitrifying polysaccharide bacteria (DGAOs) and denitrifying polyphosphate bacteria (DPAOs) in the sludge absorb the available organic matter in the sewage into the cells and store it as the internal carbon source PHA. Then the mixed liquid enters the interval aeration section. Under the action of aeration, part of the NH4 + Oxidized to NO3 by ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) - DPAOs absorb phosphate. Then it enters the anoxic cell for a short time, and DGAOs uses the stored PHA and glycogen (Gly) as electron donors and nitrate as electron acceptor to perform denitrification and remove the generated NO3 -Then continue to the aerobic zone of the aeration section for nitrification, discharge sludge at the aerobic end, discharge DPAOs for phosphorus removal, and finally enter the anoxic section. The long distance gives enough time for endogenous denitrification to completely remove NO3 in the water. - With NO2 - , completely remove nitrogen and achieve deep denitrification effect.

[0010] The method of the interval aeration sludge single return continuous flow AOA process of the present invention is characterized by:

[0011] 1) Dissolved oxygen regulation and anoxic grid switching strategy:

[0012] The precise aeration system is arranged in the third cell (2.3), the fourth cell (2.4), the seventh cell (2.7), the eighth cell (2.8) and the anoxic switching cell (2.10) of the aerobic cell. The permanent operation mode of the anoxic switching cell is the anoxic mode. The ammonia nitrogen concentration in the anoxic switching cell is controlled at 0.1-1 mg / L by an ammonia nitrogen online monitor, and the dissolved oxygen concentration in the aerobic section of the interval aeration section is controlled at 1-2 mg / L by an dissolved oxygen online detector. When the ammonia nitrogen concentration in the anoxic switching grid is greater than 1 mg / L or the average dissolved oxygen concentration in the aerobic grid is lower than 1 mg / L, the aeration of the anoxic switching grid is turned on through the PLC control system, and the operation mode is changed to aerobic. If the ammonia nitrogen concentration is still higher than 1 mg / L, the aeration volume is gradually increased by 0.1 L / min by adjusting the rotor flowmeter (2.19.3) through the aeration device; when the ammonia nitrogen concentration in the anoxic switching grid is less than 0.1 mg / L or the average dissolved oxygen concentration in the aerobic grid is higher than 2 mg / L, the aeration of the anoxic switching grid is turned off through the PLC control system, and the operation mode is changed or maintained to anoxic. If the ammonia nitrogen concentration is still lower than 0.1 mg / L, the aeration volume is gradually reduced by 0.1 L / min by adjusting the rotor flowmeter through the aeration device.

[0013] 2) Sludge single return bio-augmentation strategy:

[0014] Due to the effect of interval aeration, the carbon source of the raw water is sufficient to completely remove nitrogen from the water body, and a single sludge return strategy is adopted. The precise aeration system includes MLSS analyzers set in the front anaerobic section and the anoxic section. The MLSS analyzer controls the sludge concentration of the first compartment (2.1) of the front anaerobic section to be above 5500mg / L, and the sludge concentration of the fifteenth compartment (2.15) of the anoxic section to be below 7000mg / L. The overall reactor sludge concentration is stably maintained at 5500-7000mg / L. The sludge single return ratio is 100%. When the MLSS analyzer monitors that the sludge concentration of the anoxic section is higher than 7000mg / L, the PLC control system is controlled to adjust the sludge return ratio to 70-85%; when the MLSS analyzer monitors that the sludge concentration of the front anaerobic section is lower than 5500mg / L, the PLC control system is controlled to control the sludge return ratio to between 120-150% to ensure that the overall sludge concentration of the reactor is balanced and in a state conducive to microbial growth.

[0015] A sludge discharge mechanism is set at the bottom of the eighth compartment (2.8) of the interval aeration section and the secondary sedimentation tank (3), which is controlled by the PLC system. A sludge discharge channel is set in the eighth compartment (2.8) of the interval aeration AOA reactor, and the sludge discharge volume is 1L / d. When the data returned by the MLSS analyzer in the fifteenth compartment (2.15) of the anoxic section is higher than 7000mg / L, the sludge discharge volume is increased to 1.5L / d. If the sludge concentration monitored by the MLSS analyzer is still higher than 7000mg / L within five days, the sludge discharge volume is increased to 1.75L / d, and subsequently the sludge discharge volume is increased by 0.25L as a gradient according to whether the sludge concentration of the reactor is higher than 700 0mg / L to increase or decrease the sludge discharge volume; when the data returned by the MLSS analyzer of the first cell (2.1) of the front anaerobic cell is lower than 5500mg / L, the sludge discharge volume is reduced to 0.5L / d. If the sludge concentration monitored by the MLSS analyzer is still lower than 5500mg / L within five days, the sludge discharge channel of the eighth cell (2.8) is closed to maintain the sludge concentration in the tank body; the residual sludge in the secondary sedimentation tank is discharged through the residual sludge channel (3.3). When the height of the sludge in the secondary sedimentation tank exceeds 1 / 4 of the height of the cylindrical tank body after standing for 1.5h, the residual sludge is discharged. If it does not reach 1 / 4 of the height, the residual sludge will not be discharged.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The operation mode of the main AOA eliminates the need for digestate reflux, and the front anoxic section stores the internal carbon source of DGAOs, making full use of the raw water carbon source, making rational use of resources and reducing waste.

[0018] (2) The continuous long aerobic section is split and the aeration mode is changed to intermittent aeration. Under the premise of maintaining the original aeration volume to ensure complete nitrification, the internal carbon source consumption caused by aeration in the aerobic section is reduced. The anoxic sections interspersed between the aeration sections make timely use of the internal carbon source, minimize the waste of carbon source, and further reduce the minimum C / N threshold of deep denitrification in the AOA process.

[0019] (3) The proportions of anaerobic, aerobic and anoxic functional sections are reasonably and accurately arranged. The overall ratio of anaerobic, aerobic and anoxic is 2:4:9 or 2:5:8, which maintains sufficient time for nitrification and endogenous denitrification, and fits the optimal operation state of AOA. A sludge discharge channel is set at the end of the aerated aerobic zone for sludge discharge and phosphorus removal, and an anoxic section is set with an anoxic and anoxic switching grid to cope with the fluctuation of influent water quality with a more flexible operation mode, which has the multifunctional role of improving nitrification capacity and endogenous denitrification capacity, and improves the deep denitrification and phosphorus removal capacity of the AOA process.

[0020] (4) Due to the effect of interval aeration, the carbon source in the raw water is redistributed and reasonably utilized, and the carbon source required by the reactor is sufficient. Therefore, the secondary sludge recirculation device set up at the beginning of the anoxic stage in the AOA process to enhance denitrification is omitted, and a single recirculation operation mode is adopted to simplify the process operation, which is conducive to the transformation and optimization of the actual sewage treatment plant.

[0021] (5) The aeration mode of interval aeration is conducive to the realization and maintenance of short-term nitrification; the anoxic zone in the anoxic section and the interval aeration section can continue to add anaerobic ammonium oxidation filler to couple anaerobic ammonium oxidation and short-term nitrification, which has a relatively broad development prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of the AOA process technology and device for single-return continuous flow of interval aerated sludge. Figure 1In the figure: 1 is the water inlet tank, 1.1 is the water inlet pipe, 1.2 is the water inlet pump, 2 is the interval aeration continuous flow AOA reactor, 2.1 is the first cell of the reactor, 2.2 is the second cell, 2.3 is the third cell, 2.4 is the fourth cell, 2.5 is the fifth cell, 2.6 is the sixth cell, 2.7 is the seventh cell, 2.8 is the eighth cell, 2.9 is the ninth cell, 2.10 is the tenth cell, 2.11 is the eleventh cell, 2.12 is the twelfth cell, 2.13 is the thirteenth cell, 2.14 is the fourteenth cell, and 2.15 is the fifteenth cell; 2.1- 2.2 is the pre-anoxic section, 2.3-2.8 are the interval aeration sections, 2.9-2.15 are the anoxic sections, 2.16 is the stirring device, 2.17 is the outlet pipe, 2.18 is the water hole, 2.19 is the aeration air pump, 2.19.1 is the aeration pipe, 2.19.2 is the aeration air disc, 2.19.3 is the rotor flowmeter, 2.20 is the aerobic final sludge discharge channel, 2.21 is the sludge single return channel; 3 is the secondary sedimentation tank, 3.1 is the sludge return pump, 3.2 is the sludge return pipe, 3.3 is the residual sludge pipe, and 3.4 is the outlet pipe. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. The intermittent aeration sludge single recirculation continuous flow AOA process and device is characterized in that the whole comprises an inlet water tank (1), an intermittent aeration continuous flow AOA reactor (2), and a secondary sedimentation tank (3). The intermittent aeration continuous flow AOA reactor (2) comprises a total of 15 cells, which are divided into three parts along the water flow direction: a front anaerobic section, an intermittent aeration section, and an anoxic section, wherein the length ratio of the three sections is 2:6:7, and the alternating ratio of aerobic and anoxic in the intermittent aeration section is 1:1:1, which are aerobic, anoxic, and aerobic respectively; the inlet water tank (1) is connected to the first cell (2.1) of the intermittent aeration continuous flow AOA reactor (2) through an inlet pipe (1.1) and an inlet pump (1.2), wherein the first cell (2.1) and the second cell (2.2) are anaerobic cells, and the third cell (2 .3), the fourth cell (2.4) is an aerobic cell, the fifth cell (2.5) and the sixth cell (2.6) are anoxic cells, the seventh cell (2.7) and the eighth cell (2.8) are aerobic cells, the ninth cell (2.9) is anoxic cell, the tenth cell (2.10) is anoxic / aerobic switching cell, the eleventh cell (2.11), the twelfth cell (2.12), the thirteenth cell (2.13), the fourteenth cell (2.14) and the fifteenth cell (2.15) are all anoxic cells, and adjacent cells are connected through water holes (2.18) to prevent back-mixing and short-flow phenomena. The fifteenth cell (2.15) is connected to the secondary sedimentation tank (3) through an outlet pipe (2.17). The sludge in the sludge hopper of the secondary sedimentation tank (3) is returned to the first cell (2.1) through a sludge return pump (3.1) and a return pipe (3.2). This is a single return mode. The remaining sludge in the secondary sedimentation tank is discharged through a remaining sludge pipe (3.3), and the effluent from the secondary sedimentation tank is discharged through an outlet pipe (3.4). The aerobic cells in the aerated aerobic section are all equipped with an aeration pump (2. 19) is connected to the aeration plate (2.19.2) through an aeration pipe (2.19.1) for aeration, and each aeration plate is connected to a rotor flowmeter (2.19.3) to control the aeration volume; the anaerobic section and the anoxic section in the interval aeration continuous flow AOA reactor (2) are equipped with a stirring paddle (2.16) for uninterrupted stirring, and the aerobic grid is equipped with a WTW probe to detect the dissolved oxygen in the aerobic zone, and the aeration volume is regulated by the PLC control system.

[0024] The septic tank wastewater from a family area of ​​a university in Beijing was used as the treatment object. The specific water quality during operation was as follows: COD was 150-250 mg / L, NH4 + -N is 55-80mg / L, NO3 - -N≤1mg / L, NO2 - -N≤0.5mg / L, PO4 3- -P is 7.5-9.5mg / L. Test system such as Figure 1As shown, the effective volume of the interval aeration continuous flow AOA process reactor is 86.6L, which is divided into 15 grids, each grid has the same width, and the effective volume of the secondary sedimentation tank is 20.4L, all of which are made of acrylic sheets.

[0025] The specific operations are as follows:

[0026] The dissolved oxygen control and anoxic grid switching strategy are adopted: the precise aeration system is set in the third cell (2.3), the fourth cell (2.4), the seventh cell (2.7), the eighth cell (2.8) and the anoxic switching cell (2.10) of the aerobic cell. The permanent operation mode of the anoxic switching cell is the anoxic mode. The ammonia nitrogen concentration in the anoxic switching cell is controlled at 0.1-1 mg / L by the online ammonia nitrogen monitor, and the dissolved oxygen concentration in the aerobic section of the interval aeration section is controlled at 1-2 mg / L by the online dissolved oxygen detector. When the ammonia nitrogen concentration in the anoxic switching grid is greater than 1 mg / L or the average dissolved oxygen concentration in the aerobic grid is lower than 1 mg / L, the aeration of the anoxic switching grid is turned on through the PLC control system, and the operation mode is changed to aerobic. If the ammonia nitrogen concentration is still higher than 1 mg / L, the aeration volume is gradually increased by 0.1 L / min by adjusting the rotor flowmeter (2.19.3) through the aeration device; when the ammonia nitrogen concentration in the anoxic switching grid is less than 0.1 mg / L or the average dissolved oxygen concentration in the aerobic grid is higher than 2 mg / L, the aeration of the anoxic switching grid is turned off through the PLC control system, and the operation mode is changed or maintained to anoxic. If the ammonia nitrogen concentration is still lower than 0.1 mg / L, the aeration volume is gradually reduced by 0.1 L / min by adjusting the rotor flowmeter through the aeration device.

[0027] Adopting the strategy of single sludge return bio-enhancement: Due to the effect of interval aeration, the carbon source of raw water is sufficient to completely remove nitrogen from the water body, and the strategy of single sludge return is adopted. The precise aeration system includes MLSS analyzers set in the front anaerobic section and the anoxic section. The MLSS analyzer controls the sludge concentration of the first compartment (2.1) of the front anaerobic section to be above 5500mg / L, and the sludge concentration of the fifteenth compartment (2.15) of the anoxic section to be below 7000mg / L. The sludge concentration of the overall reactor is stably maintained at 5500-7000mg / L. The single sludge return ratio is 100%. When the MLSS analyzer monitors that the sludge concentration in the anoxic section is higher than 7000 mg / L, the sludge return ratio is adjusted to 70-85% through the PLC control system; when the MLSS analyzer monitors that the sludge concentration in the front anaerobic section is lower than 5500 mg / L, the sludge return ratio is controlled by the PLC control system to be between 120-150% to ensure that the overall sludge concentration of the reactor is balanced and in a state that is conducive to the growth of microorganisms.

[0028] A sludge discharge mechanism is set at the bottom of the eighth compartment (2.8) of the interval aeration section and the secondary sedimentation tank (3), which is controlled by the PLC system. A sludge discharge channel is set in the eighth compartment (2.8) of the interval aeration AOA reactor, and the sludge discharge volume is 1L / d. When the data returned by the MLSS analyzer in the fifteenth compartment (2.15) of the anoxic section is higher than 7000mg / L, the sludge discharge volume is increased to 1.5L / d. If the sludge concentration monitored by the MLSS analyzer is still higher than 7000mg / L within five days, the sludge discharge volume is increased to 1.75L / d, and subsequently the sludge discharge volume is increased by 0.25L as a gradient according to whether the sludge concentration of the reactor is higher than 700 0mg / L to increase or decrease the sludge discharge volume; when the data returned by the MLSS analyzer of the first cell (2.1) of the front anaerobic cell is lower than 5500mg / L, the sludge discharge volume is reduced to 0.5L / d. If the sludge concentration monitored by the MLSS analyzer is still lower than 5500mg / L within five days, the sludge discharge channel of the eighth cell (2.8) is closed to maintain the sludge concentration in the tank body; the residual sludge in the secondary sedimentation tank is discharged through the residual sludge channel (3.3). When the height of the sludge in the secondary sedimentation tank exceeds 1 / 4 of the height of the cylindrical tank body after standing for 1.5h, the residual sludge is discharged. If it does not reach 1 / 4 of the height, the residual sludge will not be discharged.

[0029] The experimental results show that: the reactor is operated with a hydraulic retention time of 12 hours. After stable operation, the effluent COD of urban low C / N domestic sewage after passing through the interval aeration continuous flow AOA process technology and device is 25-35 mg / L, NH4 + -N is lower than 0.5mg / L, NO3 - -N is lower than 2mg / L, NO2 - -N is lower than 0.5mg / L, PO4 3 -P is lower than 0.5mg / L, total nitrogen is lower than 5mg / L, reaching the ultimate denitrification level, effluent COD, NH4 + -N, TN, PO4 3 -P and other indicators have all reached the national Class A sewage treatment emission standards.

[0030] The above is a specific implementation case of this experiment, which is convenient for technicians in this technical field to better understand and apply the present invention, but the implementation of the present invention is not limited to this. Therefore, simple improvements made to the present invention by technicians in this technical field are within the scope of protection of the present invention.

Claims

1. The device used in the interval aeration sludge single return continuous flow AOA process is characterized by: The whole system comprises a water inlet tank (1), an interval aeration continuous flow AOA reactor (2), and a secondary sedimentation tank (3); The intermittent aeration continuous flow AOA reactor (2) comprises 15 cells in total, which are divided into three parts along the water flow direction: a front anaerobic section, an intermittent aeration section and an anoxic section, wherein the length ratio of the three sections is 2:6:7, and the alternating ratio of aerobic and anoxic in the intermittent aeration section is 1:1:1, which are aerobic, anoxic and aerobic respectively; the inlet water tank (1) is connected to the first cell (2.1) of the intermittent aeration continuous flow AOA reactor (2) through an inlet pipe (1.1) and an inlet pump (1.2), wherein the first cell (2.1) and the second cell (2.2) are anaerobic cells, the third cell (2.3) and the fourth cell (2.4) are aerobic cells, the fifth cell (2.5) and the sixth cell (2.6) are anoxic cells, the seventh cell (2.7) and the eighth cell (2.8) are aerobic cells. The ninth cell (2.9) is anoxic, the tenth cell (2.10) is anoxic / aerobic switching cell, the eleventh cell (2.11), the twelfth cell (2.12), the thirteenth cell (2.13), the fourteenth cell (2.14) and the fifteenth cell (2.15) are all anoxic cells, and adjacent cells are connected through water holes (2.18); the fifteenth cell (2.15) is connected to the secondary sedimentation tank (3) through an outlet pipe (2.17), and the sludge in the sludge hopper of the secondary sedimentation tank (3) is returned to the first cell (2.1) through a sludge return pump (3.1) and a return pipe (3.2), which is a single return mode, and the remaining sludge in the secondary sedimentation tank is discharged through a remaining sludge pipe (3.3), and the effluent of the secondary sedimentation tank is discharged through an outlet pipe (3.4); The aerobic cells in the intermittent aeration aerobic section are all aerated by an aeration pump (2.19) connected to an aeration plate (2.19.2) through an aeration pipe (2.19.1), and each aeration plate is connected to a rotor flow meter (2.19.3) to control the aeration volume; the anaerobic section and the anoxic section in the intermittent aeration continuous flow AOA reactor (2) are both provided with a stirring paddle (2.16), and the aerobic cells are all provided with a WTW probe to detect the dissolved oxygen in the aerobic zone, and the aeration volume is regulated by a PLC control system.

2. The device as claimed in claim 1 is used to carry out the AOA process of single-return continuous flow of interval aeration sludge, characterized in that: 1) Dissolved oxygen regulation and anoxic grid switching strategy: The precise aeration system is set in the third cell (2.3), the fourth cell (2.4), the seventh cell (2.7), the eighth cell (2.8) and the anoxic switching cell of the aerobic cell. The permanent operation mode of the anoxic switching cell is the anoxic mode. The ammonia nitrogen concentration in the anoxic switching cell is controlled at 0.1-1 mg / L by the online ammonia nitrogen monitor, and the dissolved oxygen concentration in the aerobic section of the interval aeration section is controlled at 1-2 mg / L by the online dissolved oxygen detector. When the ammonia nitrogen concentration in the anoxic switching cell is greater than 1 mg / L or the average dissolved oxygen concentration in the aerobic cell is lower than 1 mg / L, the anoxic switching cell is turned on by the PLC control system. Switch the grid for aeration and change the operation mode to aerobic. If the ammonia nitrogen concentration is still higher than 1 mg / L, the aeration device is used to adjust the rotor flow meter (2.19.3) to gradually increase the aeration volume by 0.1 L / min. When the ammonia nitrogen concentration in the anoxic switching grid is less than 0.1 mg / L or the average dissolved oxygen concentration in the aerobic grid is higher than 2 mg / L, the aeration of the anoxic switching grid is closed through the PLC control system, and the operation mode is changed or maintained to anoxic. If the ammonia nitrogen concentration is still lower than 0.1 mg / L, the aeration device is used to adjust the rotor flow meter to reduce the aeration volume by 0.1 L / min. 2) Sludge single return bio-augmentation strategy: The precise aeration system includes MLSS analyzers arranged in the front anaerobic section and the anoxic section. The MLSS analyzer is used to control the sludge concentration in the first compartment (2.1) of the front anaerobic section to be above 5500 mg / L, and the sludge concentration in the fifteenth compartment (2.15) of the anoxic section to be below 7000 mg / L. The sludge concentration of the overall reactor is stably maintained at 5500-7000 mg / L; the sludge single reflow ratio is 100%. When the MLSS analyzer monitors that the sludge concentration in the anoxic section is higher than 7000 mg / L, the sludge reflow ratio is adjusted to 70-85% through the PLC control system; when the MLSS analyzer monitors that the sludge concentration in the front anaerobic section is lower than 5500 mg / L, the sludge reflow ratio is controlled to be between 120-150% through the PLC control system.

3. The process according to claim 2, characterized in that: A sludge discharge mechanism is set at the bottom of the eighth compartment (2.8) of the interval aeration section and the secondary sedimentation tank (3), which is controlled by the PLC system. A sludge discharge channel is set in the eighth compartment (2.8) of the interval aeration AOA reactor, and the sludge discharge volume is 1L / d. When the data returned by the MLSS analyzer in the fifteenth compartment (2.15) of the anoxic section is higher than 7000mg / L, the sludge discharge volume is increased to 1.5L / d. If the sludge concentration monitored by the MLSS analyzer is still higher than 7000mg / L within five days, the sludge discharge volume is increased to 1.75L / d, and subsequently the sludge discharge volume is increased by 0.25L as a gradient according to whether the sludge concentration of the reactor is higher than 700 0mg / L to increase or decrease the sludge discharge volume; when the data returned by the MLSS analyzer of the first cell (2.1) of the front anaerobic cell is lower than 5500mg / L, the sludge discharge volume is reduced to 0.5L / d. If the sludge concentration monitored by the MLSS analyzer is still lower than 5500mg / L within five days, the sludge discharge channel of the eighth cell (2.8) is closed to maintain the sludge concentration in the tank body; the residual sludge in the secondary sedimentation tank is discharged through the residual sludge channel (3.3). When the height of the sludge in the secondary sedimentation tank exceeds 1 / 4 of the height of the cylindrical tank body after standing for 1.5h, the residual sludge is discharged. If it does not reach 1 / 4 of the height, the residual sludge will not be discharged.

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