AAOAO process sewage treatment system based on endogenous optimization and micro-aerobic control

Abstract

The invention relates to an endogenous optimization and micro-aerobic control AAOAO process sewage treatment system. The system comprises an anaerobic zone, an anoxic zone, an aerobic zone, a facultative zone, a rear anoxic zone, a rear aerobic zone, a rectangular secondary sedimentation tank, a multi-point water inlet system, a mixed liquid reflux system, a multi-point sludge reflux system, a residual sludge system, an aeration system and an online water quality feedback system, the anaerobic zone comprises a 1 # zone and a 2 # zone, the front anoxic zone comprises a 3 # zone, the aerobic zone comprises a 4 # zone and a 5 # zone, the facultative zone comprises a 6 # zone, the rear anoxic zone comprises a 7 # zone and an 8 # zone, the rear aerobic zone comprises a 9 # zone, the rectangular secondary sedimentation tank comprises a 10 # zone, and sewage sequentially passes through the 1 # zone to the 10 # zone; wherein the hydraulic retention time ratio of the anaerobic zone to the anoxic zone to the aerobic zone to the facultative zone to the rear anoxic zone to the rear aerobic zone is 2: 2: 3: 1: 5: 2; through the multi-point water inlet system, the multi-point sludge return system, the mixed liquid return system and the residual sludge system, the multi-mode sewage treatment device has the characteristics of flexible multi-mode operation, strong impact load resistance, high pollutant removal efficiency and low operation energy consumption and chemical consumption.

Description

Technical Field

[0001] The invention relates to a sewage treatment system, and in particular to an AAOAO process sewage treatment system based on endogenous optimization and micro-oxygen control. Background Art

[0002] With the improvement of social living standards and the demand for a better life, many places have formulated more stringent local standards, gradually raising the discharge standards of sewage treatment plants from Class A to Class IV or even Class III requirements of surface water, which has brought great challenges to the selection of sewage treatment process technology routes. At present, the traditional or improved AAO process (Anaerobic-Anoxic-Oxic, anaerobic-anoxic-aerobic process) is still the mainstream of urban sewage treatment plants. Under the trend of stricter requirements for TN (total nitrogen content in water) and TP (total phosphorus content in water), the Bardenpho process has gradually become a hot spot for new sewage treatment plants and upgrading with its good denitrification performance. The Bardenpho process (pre-denitrification process for denitrification energy) is to add a separate AO enhanced denitrification unit on the basis of the traditional AAO process, and reserve a carbon source addition point to temporarily add an external carbon source at low temperature and low C / N (carbon-nitrogen ratio) to ensure a good denitrification effect.

[0003] In actual projects, when the traditional AAO process cannot meet the requirement of effluent below 10 mg / L, the end of the aerobic zone is often directly divided into a post-AO unit and a carbon source is added to operate in the Bardenpho process to improve the effluent quality. However, the addition of an external carbon source is tantamount to increasing the operating drug consumption and failing to achieve effective utilization of the influent carbon source. In addition, due to the common deviation between the designed influent and the actual influent COD (Chemical Oxygen Demand) during engineering design, the aeration volume in the aerobic zone is too large and the dissolved oxygen is too high, which also increases the loss of ineffective carbon sources, making it difficult to further improve the denitrification performance. Summary of the invention

[0004] Based on the above description, the present invention provides a method to solve the technical problems in the prior art.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: An AAOAO process sewage treatment system with endogenous optimization and micro-oxygen control, comprising an anaerobic zone, an anoxic zone, an aerobic zone, an anaerobic zone, a post-anoxic zone, a post-aerobic zone, a rectangular secondary sedimentation tank, a multi-point water inlet system, a mixed liquor return system, a multi-point sludge return system, a residual sludge system, an aeration system, and an online water quality feedback system; The anaerobic zone includes Zone 1# and Zone 2#, the pre-anoxic zone includes Zone 3#, the aerobic zone includes Zone 4# and Zone 5#, the facultative anoxic zone includes Zone 6#, the post-anoxic zone includes Zone 7# and Zone 8#, the post-aerobic zone includes Zone 9#, the rectangular secondary sedimentation tank includes Zone 10#, and the sewage passes through Zone 1# to Zone 10# in sequence; wherein, the hydraulic retention time ratio of the anaerobic zone, the anoxic zone, the aerobic zone, the facultative anoxic zone, the post-anoxic zone, and the post-aerobic zone is 2:2:3:1:5:2.

[0006] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: The AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control provided in the present application has the characteristics of flexible multi-mode operation, strong resistance to shock loads, high pollutant removal efficiency, and low operating energy and drug consumption through a multi-point water inlet system, a multi-point sludge return system, a mixed liquor return system, and a residual sludge system.

[0007] Based on the above technical solution, the present invention can also be improved as follows.

[0008] Furthermore, vertical turbine mixers are provided in the 1# zone and the 2# zone, flow promoters are provided in the 3# zone, the 5# zone, the 7# zone, the 8# zone and the 9# zone; and submersible mixers are provided in the 4# zone and the 6# zone.

[0009] Furthermore, biological carrier fillers are arranged in area 1#, area 2#, area 3#, area 7# and area 8#.

[0010] Furthermore, the multi-point water inlet system is distributed to areas 1#, 3#, 6#, and 7# through the water inlet pipe through the water distribution well and the water inlet distribution channel. The distribution ratio is adjusted through the weir valve according to the inlet water quality.

[0011] Furthermore, mixed liquid reflux pumps are provided in Zone 5# and Zone 6#, and the mixed liquid is refluxed from Zone 5# or Zone 6# to Zone 3# through the mixed liquid reflux pumps. When Zone 6# operates in an aerobic manner, the mixed liquid reflux pump in Zone 6# is turned on; when Zone 6# operates in an anoxic manner, the mixed liquid reflux pump in Zone 5# is turned on.

[0012] Furthermore, the multi-point sludge return system C includes a sludge return pump, a sludge return well, a scraper, a sludge collecting tank, a sludge well and a sludge discharge pipe. The sludge settled in area 10# is pushed into the sludge collecting tank by the scraper. Under the action of hydrostatic pressure, the bottom sludge enters the sludge discharge tank through the sludge discharge pipe and flows into the sludge well. It is lifted to the sludge return well by the sludge return pump and distributed to areas 1#, 6#, 7# and 9# through the sludge return channel.

[0013] Furthermore, the aeration system is composed of a slat-type microporous aerator and a blower, wherein the 4# zone and the 9# zone are high aeration zones, and the 5# zone and the 6# zone are low aeration zones.

[0014] Furthermore, the online water quality feedback system includes an online instrument sampling tube, which is arranged in the water outlet well of the 10# zone.

[0015] Furthermore, when the water temperature is higher than a predetermined water temperature threshold, the system is in a summer operation mode, the facultative anoxic zone is adjusted to an anoxic state, the water inlet ratio is 1:2, and the hydraulic retention time ratios of the anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone are 2:2:3:6:2; the mixed liquor reflow ratio is 100%, and a two-point sludge reflow method is adopted, and the sludge reflow ratios are 100% and 100%; when the water temperature is lower than a predetermined water temperature threshold, the system is in a winter operation mode, the facultative anoxic zone is adjusted to an aerobic state, the water inlet ratio is 1:2, and the hydraulic retention time ratios of the anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone are 2:2:4:5:2, and a three-point sludge reflow method is adopted, and the sludge reflow ratios are 100%, 100%, and 50%~100%.

[0016] Furthermore, when the BOD5 / TN in the influent is greater than 3.5, the system adopts an energy-saving operation mode, the facultative anoxic zone is adjusted to an aerobic state, the influent ratio is 2:1, and the hydraulic retention time ratio of the anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone is 2:2:4:5:2; the mixed liquor return ratio is 100%, a single-point sludge return method is adopted, and the sludge return ratio is 100%; when the BOD5 / TN in the influent is less than 3.5, the system adopts a high-performance operation mode, the facultative anoxic zone is adjusted to an anoxic state, the influent ratio is 1:2:1, the hydraulic retention time ratio of the anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone is 2:2:3:6:2, the mixed liquor return ratio is 200%, a two-point return method is adopted, and the sludge return ratio is 100%:100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A process flow chart of an AAOAO process sewage treatment system with endogenous optimization and micro-oxygen control provided by an embodiment of the present invention; Figure 2 A structural plan view of an AAOAO process sewage treatment system with endogenous optimization and micro-oxygen control provided by an embodiment of the present invention; Figure 3 for Figure 2 A schematic cross-sectional view along the 1-1 direction; Figure 4 for Figure 2 A schematic cross-sectional view along the 2-2 direction; Figure 5 This is a process flow chart of the summer operation mode of an embodiment of the present application; Figure 6 This is a process flow chart of the winter operation mode of an embodiment of the present application; Figure 7 This is a process flow chart of the energy-saving operation mode of an embodiment of the present application; Figure 8 This is a process flow chart of the high-performance operation mode of an embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0020] It will be appreciated that spatial relationship terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It will be appreciated that, in addition to the orientations shown in the figures, spatial relationship terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, an element or feature described as "under other elements" or "under it" or "under it" will be oriented as "on" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90° or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0021] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. The "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0022] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0023] like Figure 1 As shown, the present application provides an AAOAO process sewage treatment system with endogenous optimization and micro-oxygen control; it includes an anaerobic zone, an anoxic zone, an aerobic zone, an anaerobic zone, a post-anoxic zone, a post-aerobic zone, a rectangular secondary sedimentation tank, a multi-point water inlet system A, a mixed liquor return system B, a multi-point sludge return system C, a residual sludge system D, an aeration system E, and an online water quality feedback system F.

[0024] Among them, combined Figure 2-4 As shown, the anaerobic zone includes Zone 1# and Zone 2#, the pre-anoxic zone includes Zone 3#, the aerobic zone includes Zone 4# and Zone 5#, the facultative anoxic zone includes Zone 6#, the post-anoxic zone includes Zone 7# and Zone 8#, the post-aerobic zone includes Zone 9#, the rectangular secondary sedimentation tank includes Zone 10#, and the sewage passes through Zone 1# to Zone 10# in sequence; among which, the hydraulic retention time ratio (volume ratio) of the anaerobic zone, anoxic zone, aerobic zone, facultative anoxic zone, post-anoxic zone, and post-aerobic zone is 2:2:3:1:5:2.

[0025] By setting up an anaerobic zone, the aerobic / anoxic state can be adjusted according to the seasonal changes in the inlet water quality and water temperature, thereby increasing the hydraulic retention time of the overall aerobic or anoxic zone of the system, promoting aerobic reactions or denitrification reactions in a targeted manner, and meeting the effluent water quality requirements.

[0026] Specifically, according to the adjustment of the facultative anoxic zone, the residence time of each reaction zone can be controllably adjusted to 2:2:3:6:2 and 2:2:4:5:2 to meet the needs of different water quality and seasonal regulation; the residence time in the aerobic zone is shorter than that in the traditional biochemical pond, which helps to reduce the ineffective oxidation of carbon sources in the raw water, preserve more carbon sources for the subsequent anoxic zone, and enhance the denitrification efficiency.

[0027] The secondary sedimentation tank adopts a rectangular secondary sedimentation tank, which can be built together with the biochemical tank to reduce the floor space. It uses hydrostatic pressure to discharge mud, which is simple to operate and requires less equipment. The surface of the secondary sedimentation tank is equipped with an electric skimming pipe, and a slag discharge trough is opened on its side to discharge floating slag through timed rotation. Preferably, vertical turbine mixers 5 are provided in the 1# zone and the 2# zone, and the anaerobic zone adopts a vertical turbine mixer, which has a better mixing effect than the conventional plug flow type and avoids short-flow and dead zone phenomena.

[0028] Flow promoters 7 are provided in 3#, 5#, 7#, 8# and 9# areas; submersible mixers 9 are provided in 4# and 6# areas to improve mixing effect and prevent sludge sedimentation and short-circuiting; aeration systems E are provided in 4#, 5#, 6# and 9# areas.

[0029] Biological carrier fillers 32 are provided in 1#, 2#, 3#, 7#, and 8# zones. By adding biological carrier fillers 32 to the anaerobic and anoxic zones, a mud film composite process is formed to increase the amount of microorganisms in the reaction zone, promote anaerobic phosphorus release and anoxic denitrification efficiency, and set a screen in front of the outlet hole to prevent the biological carrier fillers from flowing into the next reaction zone. A screen 8 is provided in front of the corresponding outlet hole; a sludge scraper 29, an electric slag skimmer 30, a sludge collecting tank 23, and a sludge discharge pipe 24 are provided in 10# zone, wherein the sludge collecting tank 23 is set according to a predetermined slope, and the effluent from 9# zone passes through the outlet weir 16 into the water distribution tank 17, enters the sedimentation zone under the steady flow action of the water distribution hole 18 and the water retaining plate 19, and after sludge sedimentation, the effluent passes through the slag retaining plate 22 and the triangular weir 21, enters the outlet tank 20, and merges into the outlet well 23, and finally enters the next treatment unit through the outlet pipe 28.

[0030] The multi-point water inlet system A is distributed to areas 1#, 3#, 6# and 7# by the water inlet pipe 1 through the water distribution well 2 (with a water weir 3 inside to ensure the overall water level stability) and the water inlet distribution channel 4. The distribution ratio can be adjusted through the weir valve 12 according to the water quality of the inlet water.

[0031] Through the multi-point water inlet system, the organic carbon source in the raw water is preferentially distributed to the anoxic zone to supplement the denitrification carbon source, improve the utilization rate of the carbon source in the inlet water, and promote the improvement of denitrification denitrification efficiency.

[0032] The mixed liquor reflux system B refluxes from zone 5# or zone 6# to zone 3# through the mixed liquor reflux pump 15. When zone 6# operates in aerobic mode, the mixed liquor reflux pump 15 in zone 6# is turned on. When zone 6# operates in anoxic mode, the mixed liquor reflux pump in zone 5# is turned on.

[0033] The multi-point sludge return system C includes a sludge return pump 11, a sludge return well 13, a scraper 29, a sludge collecting tank 23, a sludge well 26 and a sludge discharge pipe 24. The sludge deposited in area 10# is pushed into the sludge collecting tank 23 by the scraper 29. Under the action of hydrostatic pressure, the bottom sludge enters the sludge discharge tank 25 through the sludge discharge pipe 24 and flows into the sludge well 26. It is lifted to the sludge return well 13 by the sludge return pump 11 and distributed to areas 1#, 6#, 7# and 9# by the sludge return channel 14. The total return ratio can be 200%, and the distribution ratio can be adjusted through the weir valve 12 according to the inlet water quality.

[0034] Through multi-point sludge return, sludge is returned to the anaerobic zone, post-anoxic zone, and post-aerobic zone respectively, the sludge concentration is increased, and the reaction rate is increased when the temperature is low in winter and the raw water carbon source is insufficient; among them, the mixed liquid return and sludge return are both channeled and through-the-wall pumped, without pipelines, which can avoid the blockage of pipelines and valves, facilitate maintenance and management, and save operation and maintenance costs The residual sludge system D includes a residual sludge pipe 27, which passes from the sludge well 26 in area 10# to the sludge treatment system.

[0035] The aeration system E is composed of a slat-type microporous aerator 10 and a blower, wherein the 4# and 9# zones are high aeration zones, and the 5# and 6# zones are low aeration zones. The slat-type microporous aerator 10 has high oxygenation efficiency and can realize dissolved oxygen control under low aeration volume; wherein, the aerobic zone is divided into a low aeration zone and a high aeration zone, and the low aeration zone realizes micro-oxygen control to reduce the ineffective consumption of carbon sources in the raw water and prevent sludge sedimentation; the high aeration zone is conventionally controlled for dissolved oxygen to ensure that the effluent ammonia nitrogen meets the standard; micro-oxygen operation is conducive to the realization of synchronous nitrification and denitrification and short-range nitrification and denitrification reactions, reduces the amount of carbon source required for denitrification per unit of total nitrogen, and improves the denitrification performance when the carbon source in the raw water is limited.

[0036] The online water quality feedback system F includes an online instrument sampling tube 33, which is arranged in the outlet well 23 of the 10# zone and is used for online ammonia nitrogen and COD detection. According to the outlet water quality, the blower aeration volume is automatically adjusted to achieve dissolved oxygen control and energy-saving operation.

[0037] The effluent from the 10# area of ​​the secondary sedimentation tank is equipped with an online water quality feedback system F, which can judge the aerobic reaction performance based on the effluent ammonia nitrogen and COD. On the premise of ensuring that the ammonia nitrogen and COD meet the standards, the aeration volume is reduced as much as possible, micro-aerobic operation is maintained, the denitrification and nitrogen removal efficiency is improved, water quality improvement and energy conservation and consumption reduction are promoted, thereby reducing carbon emissions.

[0038] When the AAOAO process sewage treatment system provided by the present application is used, the sewage passes through the water inlet pipe 1, the water distribution well 2, and the water inlet distribution channel 4 to be distributed to the 1# area, the 3# area, the 6# area, and the 7# area; anaerobic phosphorus release reaction is carried out in the 1# area and the 2# area. Anoxic denitrification reaction is carried out in the 3# area, the 7# area, and the 8# area; aerobic organic matter and ammonia nitrogen oxidation reaction is carried out in the 4# area, the 5# area, and the 9# area; and aerobic or anoxic reaction is carried out in the 6# area.

[0039] The nitrate produced by the aerobic reaction in the 5# or 6# zone is refluxed to the 3# zone for denitrification through the mixed liquid reflux pump 15; the effluent from the 9# zone enters the 10# zone for mud and water separation, and the effluent passes through the outlet trough 20, flows into the outlet well 23, and finally enters the next treatment unit through the outlet pipe 28.

[0040] The sludge in the 10# zone is pushed into the sludge collecting tank 23 by the scraper 29. Under the action of hydrostatic pressure, the bottom sludge enters the sludge discharge tank 25 through the sludge discharge pipe 24. The sludge on the surface of the secondary sedimentation tank is enriched in the electric skimming pipe 30 under the plugging action of the scraper 29. The sludge discharge tank is opened on the side thereof, and the sludge discharge function is achieved through timed rotation. The sludge flows into the sludge discharge tank 25 through the pipeline. The sludge in the sludge discharge tank 25 flows into the sludge well 26, is lifted to the sludge return well 13 by the sludge return pump 11, and is distributed to the 1# zone, the 6# zone, the 7# zone, and the 9# zone by the sludge return channel 14. At the same time, the remaining sludge in the sludge well 26 is discharged to the sludge treatment unit through the remaining sludge pipe 27.

[0041] It can also realize multi-mode operation under different water inlet conditions: (1) When the water temperature is higher than 16℃, Figure 5 As shown in the figure, this is the summer operation mode, during which multi-point water inlet and micro-oxygen control can be adopted (DO at the end of the aerobic zone is controlled at about 1.0 mg / L, and DO at the end of the post-aerobic zone is controlled at about 2.0 mg / L), effectively improving the utilization rate of carbon sources in the inlet water, strengthening the denitrification effect of the two anoxic zones before and after, and achieving effluent TN of 7-9 mg / L, meeting the surface water level Class IV standard, while reducing the operating energy consumption by about 2.5%; the hydraulic retention time ratio (volume ratio) of the anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone is 2:2:3:6:2, the inlet ratio is 1:2, the mixed liquor return ratio is 100%, and the multi-point sludge return ratios are 100% and 100%.

[0042] (2) When the water temperature is below 16°C, Figure 6 As shown, this is the winter operating condition. By increasing the internal recirculation, extending the sludge age and increasing the aeration volume; the DO at the end of the aerobic zone is controlled at about 2.0 mg / L to enhance the efficiency of aerobic reaction and ensure that the effluent quality is better than the Class A discharge standard; the hydraulic retention time ratio (volume ratio) of the anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone and post-aerobic zone is 2:2:4:5:2, the inlet ratio is 1:2, the mixed liquor return ratio is 150%~200%, and the multi-point sludge return ratios are 100%, 100% and 50%~100%.

[0043] (3) If the carbon source in the influent is sufficient and the BOD5 / TN (ratio of biochemical oxygen demand to total nitrogen in 5 days) is greater than 3.5, the energy-saving operation mode can be adopted; Figure 7 As shown, the hydraulic retention time ratio (volume ratio) of the anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone is 2:2:4:5:2, the inlet ratio is 2:1, the mixed liquor return ratio is 100%, and the multi-point sludge return ratio is 100%.

[0044] (4) If the carbon source in the influent is insufficient and BOD5 / TN is less than 3.5, a high-performance operation mode can be adopted, such as Figure 8As shown, multi-point water inlet and micro-aerobic control are adopted (DO at the end of aerobic zone is controlled at about 1.0 mg / L, and DO at the end of post-aerobic zone is controlled at about 2.0 mg / L); the hydraulic retention time ratio (volume ratio) of anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone and post-aerobic zone is 2:2:3:6:2, the inlet ratio is 1:2:1, the mixed liquor return ratio is 200%, and the multi-point sludge return ratio is 100%:100%.

[0045] The following is a detailed description of the present application system in combination with two test scenarios in actual use.

[0046] The first test was conducted on a pilot scale in a sewage treatment plant in Wuhan, Hubei, with a sewage treatment capacity of 4.5 m³ / d (cubic meters per day). The process flow and treatment system settings of the test were consistent with the invention patent applied for, which was "AAOAO process sewage treatment system based on endogenous optimization and micro-oxygen control". The raw water for the test was taken from the effluent of the plant's grit chamber. The design parameters and operating parameters are as follows: (1) HRT (total hydraulic retention time) is 15 h, including 2 h in the anaerobic zone, 2 h in the anoxic zone, 3 h in the aerobic zone, 1 h in the facultative anoxic zone, 5 h in the post-anoxic zone, and 2 h in the post-aerobic zone.

[0047] (2) Summer operating conditions (water temperature 8~10℃) The facultative anoxic zone adopts anoxic operation, and the anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone adopt 2:2:3:6:2; Multi-point water inlet system: distributed to Zone 1# and Zone 3# by the water inlet pipe, with a distribution ratio of 1:2, and the water inlet volumes are: Zone 1# (1.5 m³ / d), Zone 3# (3.0 m³ / d); Mixed liquid reflux system: refluxes from the end of the aerobic zone to the beginning of the anoxic zone, that is, from zone 5# to zone 3#, with a mixed liquid reflux pump, the reflux ratio is 100%, and the reflux volume is 4.5 m³ / d; Multi-point sludge return system: from the secondary sedimentation tank to the anaerobic zone and the facultative aerobic zone, i.e., Zone 1# and Zone 6#, the total return ratio is 200%, the distribution ratio is 1:1, and the sludge return volumes are: Zone 1# (4.5 m³ / d), Zone 6# (4.5 m³ / d); Sludge concentration: anaerobic zone 3120 mg / L, anoxic zone 2840 mg / L, aerobic zone 3230 mg / L, post-anoxic zone 3550 mg / L, post-aerobic zone 2630 mg / L; Residual sludge system: from the sludge well in area 10# to the sludge treatment system, the discharge volume is 2 L / d (sludge age is 7 days); Aeration system: The aeration system in zones 4# and 9# is a high aeration zone (dissolved oxygen is 1.5 mg / L), and zone 5# is a low aeration zone (dissolved oxygen is 0.8 mg / L).

[0048] Rectangular sedimentation tank: surface load is 0.6 m3 / m2·h and area is 0.3 m2.

[0049] (3) Winter operating conditions (water temperature 16~26℃) The facultative anoxic zone adopts anoxic operation, and the anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone adopt 2:2:4:5:2; Multi-point water inlet system: distributed to Zone 1# and Zone 3# by the water inlet pipe, with a distribution ratio of 1:2, and the water inlet volumes are: Zone 1# (1.5 m³ / d), Zone 3# (3.0 m³ / d); Mixed liquid reflux system: refluxes from the end of the anoxic zone to the beginning of the anoxic zone, that is, from zone 6# to zone 3#, with a mixed liquid reflux pump, the reflux ratio is 200%, and the reflux volume is 9.0 m³ / d; Multi-point sludge return system: from the secondary sedimentation tank to the anaerobic zone, anoxic zone and post-aerobic zone, i.e. Zone 1#, Zone 7# and Zone 9#, the total return ratio is 250%, the distribution ratio is 2:2:1, and the sludge return volumes are: Zone 1# (4.5 m³ / d), Zone 7# (4.5 m³ / d) and Zone 9# (2.25 m³ / d); Sludge concentration: anaerobic zone 3510 mg / L, anoxic zone 3070 mg / L, aerobic zone 2820 mg / L, post-anoxic zone 4170 mg / L, post-aerobic zone 3830 mg / L; Residual sludge system: from the sludge well in area 10# to the sludge treatment system, the discharge volume is 1.4 L / d (sludge age is 10 days); Aeration system: The aeration system in zones 4# and 9# is a high aeration zone (dissolved oxygen is 2.0 mg / L), and zone 5# is a low aeration zone (dissolved oxygen is 1.5 mg / L).

[0050] Rectangular sedimentation tank: surface load is 0.6 m3 / m2·h and area is 0.3 m2.

[0051] The water quality of the inlet and outlet water after three months of operation is as shown in Table 1:

[0052] Test conclusion: In this pilot test, the summer effluent COD, BOD, ammonia nitrogen and total phosphorus all meet the Class IV water body standards in the "Surface Water Environmental Quality Standard" GB 3838-2002, and the total nitrogen is better than the Class A standard in the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants". In winter, COD and ammonia nitrogen all meet the Class IV water body standards in the "Surface Water Environmental Quality Standard" GB 3838-2002, and the other indicators meet the Class A standard.

[0053] The second test was conducted on a pilot scale in a sewage treatment plant in Wuhan, with a sewage treatment capacity of 120 m³ / d. The process flow and treatment system settings of the test were consistent with the invention patent applied for, which was "AAOAO process sewage treatment system based on endogenous optimization and micro-oxygen control". The test raw water was taken from the effluent of the plant's grit chamber, and the main data was collected in summer. The water temperature was 18~25℃, and the design parameters and operation parameters were as follows: (1) HRT (total hydraulic retention time) = 16.5 h, including 2.2 h in anaerobic zone, 2.2 h in anoxic zone, 3.3 h in aerobic zone, 1.1 h in facultative anoxic zone, 5.5 h in post-anoxic zone, and 2.2 h in post-aerobic zone.

[0054] (2) The facultative anoxic zone adopts anoxic operation, and the anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone adopt 2:2:3:6:2; Multi-point water inlet system: distributed to 1# zone, 3# zone and 6# zone by the water inlet pipe, with the distribution ratio of 1:2:1, and the water inlet volume is: 1# zone (30 m³ / d), 3# zone (60 m³ / d), 6# zone (30 m³ / d); (3) Mixed liquid reflux system: refluxes from the end of the aerobic zone to the beginning of the anoxic zone, i.e., zone 5# to zone 3#. A mixed liquid reflux pump is provided. The reflux ratio is 200% and the reflux volume is 240 m³ / d. (4) Multi-point sludge return system: from the secondary sedimentation tank to the anaerobic zone and the facultative aerobic zone, i.e., Zone 1# and Zone 6#, the total return ratio is 200%, the distribution ratio is 1:1, and the sludge return volumes are: Zone 1# (120 m³ / d), Zone 6# (120 m³ / d); (5) Sludge concentration: anaerobic zone 3650 mg / L, anoxic zone 2870 mg / L, aerobic zone 2650 mg / L, post-anoxic zone 3910 mg / L, post-aerobic zone 3220 mg / L; (6) Residual sludge system: from the sludge well in area 10# to the sludge treatment system, the discharge volume is 40 L / d (sludge age is 7 days); (7) Aeration system: The aeration system in zones 4# and 9# is a high aeration zone (dissolved oxygen is 1.3 mg / L), and zone 5# is a low aeration zone (dissolved oxygen is 0.7 mg / L).

[0055] (8) Rectangular sedimentation tank: surface load is 1.25 m3 / m2·h and area is 4 m2.

[0056] The inlet and outlet water conditions of the pilot test after 3 months of operation are as follows:

[0057] In this pilot test, the influent BOD5 / TN was 2~3, less than 3.5, and the raw water carbon source was insufficient.

[0058] Test conclusion: The COD, BOD, ammonia nitrogen and total phosphorus of the effluent in summer all meet the Class IV water body standards in the "Surface Water Environmental Quality Standards" GB 3838-2002, and the total nitrogen is better than the Level A standard in the "Pollutant Discharge Standards for Urban Wastewater Treatment Plants".

[0059] In summary, compared with the conventional AAO process and Bardenpho process, the AAOAO process sewage treatment system with endogenous optimization and micro-oxygen control provided in this application has the longest residence time in the post-anoxic zone, and can achieve 100% of the nitrate produced in the aerobic zone to enter the anoxic zone for full denitrification and denitrification, which is not affected by the mixed liquor reflow ratio and can break through the limitation of the theoretical denitrification rate limit value; compared with the traditional biochemical pool, different operation control methods can be adopted under different water quality and seasons to adjust the residence time in the aerobic zone and the post-anoxic zone, dissolved oxygen control, multi-point water inlet ratio, multi-point sludge return ratio, mixed liquor return point, etc., so as to achieve the requirements of Class IV surface water level standards (TN=7~9 mg / L) for effluent in summer and Class A discharge standards for effluent in winter; energy-saving operation when the influent carbon source is sufficient, and high-performance operation when the carbon source is insufficient, so as to achieve synergistic and efficient pollution reduction and carbon reduction.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control, characterized in that: Including anaerobic zone, anoxic zone, aerobic zone, facultative anoxic zone, post-anoxic zone, post-aerobic zone, rectangular secondary sedimentation tank, multi-point water inlet system, mixed liquor return system, multi-point sludge return system, excess sludge system, aeration system, online water quality feedback system; The anaerobic zone includes Zone 1# and Zone 2#, the pre-anoxic zone includes Zone 3#, the aerobic zone includes Zone 4# and Zone 5#, the facultative anoxic zone includes Zone 6#, the post-anoxic zone includes Zone 7# and Zone 8#, the post-aerobic zone includes Zone 9#, the rectangular secondary sedimentation tank includes Zone 10#, and the sewage passes through Zone 1# to Zone 10# in sequence; wherein, the hydraulic retention time ratio of the anaerobic zone, the anoxic zone, the aerobic zone, the facultative anoxic zone, the post-anoxic zone, and the post-aerobic zone is 2:2:3:1:5:

2.

2. The AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control according to claim 1 is characterized in that: The 1# zone and the 2# zone are provided with vertical turbine mixers, the 3# zone, the 5# zone, the 7# zone, the 8# zone and the 9# zone are provided with flow promoters; the 4# zone and the 6# zone are provided with submersible mixers.

3. The AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control according to claim 1 is characterized in that: Biological carrier fillers are installed in Area 1#, Area 2#, Area 3#, Area 7# and Area 8#.

4. The AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control according to claim 1 is characterized in that: The multi-point water inlet system is distributed to Area 1#, Area 3#, Area 6#, and Area 7# through the water inlet pipe through the water distribution well and the water inlet distribution channel. The distribution ratio is adjusted through the weir valve according to the inlet water quality.

5. The AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control according to claim 1 is characterized in that: Mixed liquid reflux pumps are installed in Zone 5# and Zone 6#. The mixed liquid flows back from Zone 5# or Zone 6# to Zone 3# through the mixed liquid reflux pumps. When Zone 6# operates in aerobic mode, the mixed liquid reflux pump in Zone 6# is turned on. When Zone 6# operates in anoxic mode, the mixed liquid reflux pump in Zone 5# is turned on.

6. The AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control according to claim 1 is characterized in that: The multi-point sludge return system C includes a sludge return pump, a sludge return well, a scraper, a sludge collecting tank, a sludge well and a sludge discharge pipe. The sludge settled in area 10# is pushed into the sludge collecting tank by the scraper. Under the action of hydrostatic pressure, the bottom sludge enters the sludge discharge tank through the sludge discharge pipe and flows into the sludge well. It is lifted to the sludge return well by the sludge return pump and distributed to areas 1#, 6#, 7# and 9# through the sludge return channel.

7. The AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control according to claim 1 is characterized in that: The aeration system is composed of a slat-type microporous aerator and a blower, wherein the 4# zone and the 9# zone are high aeration zones, and the 5# zone and the 6# zone are low aeration zones.

8. The AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control according to claim 1 is characterized in that: The online water quality feedback system includes an online instrument sampling tube, which is arranged in the water outlet well of the 10# zone.

9. The AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control according to claim 1 is characterized in that: When the water temperature is higher than the preset water temperature threshold, the system is in the summer operation mode, the facultative anoxic zone is adjusted to the anoxic state, the water inlet ratio is 1:2, the hydraulic retention time ratio of the anoxic zone, the aerobic zone, the post-anoxic zone, and the post-aerobic zone is 2:2:3:6:2, the mixed liquor return ratio is 100%, and a two-point sludge return method is adopted, and the sludge return ratio is 100% and 100%; when the water temperature is lower than the preset water temperature threshold, the system is in the winter operation mode, the facultative anoxic zone is adjusted to the aerobic state, the water inlet ratio is 1:2, the hydraulic retention time ratio of the anoxic zone, the aerobic zone, the post-anoxic zone, and the post-aerobic zone is 2:2:4:5:2, and a three-point sludge return method is adopted, and the sludge return ratio is 100%, 100% and 50%~100%.

10. The AAOAO process wastewater treatment system based on endogenous optimization and micro-oxygen control according to claim 1 is characterized in that: When the BOD5 / TN in the influent is greater than 3.5, the system adopts the energy-saving operation mode, the anoxic zone is adjusted to the aerobic state, the inlet ratio is 2:1, the hydraulic retention time ratio of the anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone is 2:2:4:5:2, the mixed liquor return ratio is 100%, and a single-point sludge return method is adopted, and the sludge return ratio is 100%; when the BOD5 / TN in the influent is less than 3.5, the system adopts the high-performance operation mode, the anoxic zone is adjusted to the anoxic state, the inlet ratio is 1:2:1, the hydraulic retention time ratio of the anaerobic zone, anoxic zone, aerobic zone, post-anoxic zone, and post-aerobic zone is 2:2:3:6:2, the mixed liquor return ratio is 200%, a two-point return method is adopted, and the sludge return ratio is 100%:100%.

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