Aeration-stirring coupling operation method of aerobic tank of sewage treatment based on load dynamic regulation and operation method thereof

Abstract

The present application belongs to the technical field of sewage treatment, and specifically provides a sewage treatment aerobic tank aeration-stirring coupling operation method based on load dynamic regulation and control and an operation method. Water quality parameters are collected; the load level is determined according to the water quality parameters, and the aeration-stirring coupling operation mode of the end region of the aerobic tank is selected correspondingly, the operation mode including a high load mode, a conventional load mode and a low load mode; a gradually decreasing aeration strategy is implemented on the microporous aeration device at the front, middle and end of the aerobic tank; based on the selected operation mode, the start-stop state of the microporous aeration device and the mechanical stirring device at the end region is controlled; the dissolved oxygen value at the end of the aerobic tank and the final effluent quality are monitored, and the microporous aeration device is adjusted so that the end DO is stabilized in the target range and the effluent quality meets the standard. Through the gradually decreasing aeration design and the intelligent operation strategy of aeration-stirring coupling, the control of the dissolved oxygen at the end of the aerobic tank is realized, and the aeration energy consumption of the sewage treatment plant is significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically, it relates to a method for coupled aeration-stirring operation of an aerobic tank for wastewater treatment based on dynamic load control, and the operation method thereof. Background Technology

[0002] The secondary biological treatment stage is the core of energy consumption in a wastewater treatment plant, with its aeration system accounting for 40%-60% of the total energy consumption, making energy waste a particularly prominent issue. Under low-load conditions, maintaining excessively long hydraulic retention times and excessively high dissolved oxygen (DO, typically >2.0 mg / L) according to design parameters will result in huge energy losses.

[0003] While existing technologies have introduced energy-saving measures such as variable frequency blowers and precision aeration, most remain limited to uniformly controlling the dissolved oxygen (DO) levels throughout the entire aerobic tank, failing to precisely match the oxygen demand patterns of pollutant degradation along the tank's length. Particularly at the end of the aerobic tank, where pollutant concentrations are significantly reduced and the microbial oxygen consumption rate (OUR) has decreased markedly, the aeration intensity under traditional uniform aeration modes is severely mismatched with actual oxygen demand, inevitably leading to inefficient energy consumption. Furthermore, simply reducing DO to excessively low levels (e.g., <0.3 mg / L) can also cause risks such as deterioration of sludge settling performance and inhibition of nitrification, affecting the stability of effluent quality.

[0004] Therefore, there is an urgent need for a technical solution that can precisely control the aerobic tank according to the dynamic changes in the influent load, and achieve maximum energy saving while ensuring stable and compliant treatment results. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and operation method for aeration-stirring coupled operation of aerobic tank in sewage treatment based on dynamic load control. Through the intelligent operation strategy of gradually decreasing aeration design and aeration-stirring coupling, the dissolved oxygen at the end of the aerobic tank can be controlled, which significantly reduces the aeration energy consumption of sewage treatment plants.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an aeration-stirring coupled system for aerobic tanks in wastewater treatment based on dynamic load regulation, comprising: The wastewater treatment system includes an anaerobic tank, an anoxic tank, and an aerobic tank connected in sequence. The aerobic tank is divided into three areas: a front section, a middle section, and a terminal section. The gradual reduction aeration system includes microporous aeration devices arranged along the water flow direction of the aerobic tank; A mixing system is provided, with a mechanical mixing device installed at the end of the aerobic tank. Online instruments: At least online DO meters and mixed liquor suspended solids concentration meters should be installed at the front, middle and end of the aerobic tank, and online water quality analyzers should be installed at the inlet and outlet of the wastewater treatment system; Intelligent control platform: Receives data from the detection system, uses the influent pollutant load as the feedforward signal and the DO at the end of the aerobic tank and the effluent water quality as feedback signals, and dynamically regulates the start and stop of the microporous aeration device and the mechanical stirring device.

[0007] In the preferred embodiment, the aerobic tank is divided into a front section, a middle section, and an end section in a 4:3:3 ratio.

[0008] In the preferred embodiment, the aerator arrangement density of the microporous aeration devices in the front, middle and end sections of the gradually decreasing aeration system decreases sequentially.

[0009] In the preferred embodiment, in the gradually decreasing aeration system, the aerator pore size and arrangement density of the microporous aeration device are optimized based on a model relating air volume per unit aeration area to oxygen mass transfer efficiency. The calculation formula is as follows: d=k1 (Q / (S θ))¹ / ³+k2; Where d is the bubble diameter; Q / (S θ) represents the air volume per unit aeration area, Q is the influent flow rate, and S is the aeration area; θ refers to the hydraulic retention time; k1 and k2 are coefficients obtained through experiments. Based on the varying properties of activated sludge mixed liquor from different wastewater treatment plants, k1 ranges from 1.3 to 1.5 × 10⁻⁶. 4 The value of k2 ranges from 1.4 to 1.6 × 10⁻⁶. 4 .

[0010] In a preferred embodiment, the intelligent control platform is configured to execute one of the following operating modes: High-load mode: When the concentration of pollutants in the influent exceeds the first set threshold, the microporous aeration device is activated in the front, middle and terminal sections, the mechanical stirring device is activated at the same time, and the DO at the terminal is controlled at 1.6-2.5 mg / L.

[0011] Normal load mode: When the influent pollutant concentration is between the first and second set thresholds, the microporous aeration devices are turned on in the front, middle and end sections, and the mechanical stirring device can be turned on intermittently to control the terminal DO at 0.8-1.6 mg / L.

[0012] Low load mode: When the concentration of pollutants in the influent is lower than the second set threshold, the microporous aeration device is turned on in the front and middle sections and turned off in the terminal section. The mechanical stirring device is turned on to control the terminal DO to be maintained at 0.3-0.5 mg / L.

[0013] This invention also provides a method for coupled aeration-stirring operation of an aerobic tank in wastewater treatment based on dynamic load control, comprising the following steps: S1. Real-time monitoring and load calculation: Influent water quality parameters are collected through online instruments; S2. Determine the load level and select the operating mode: Determine the load level based on the influent water quality parameters, and select the corresponding aeration-stirring coupled operating mode for the end area of ​​the aerobic tank. The operating modes include high load mode, normal load mode and low load mode. S3. Implement zoned control and equipment start-up and shutdown: Implement a gradual reduction aeration strategy for the microporous aeration devices in the front, middle and end sections of the aerobic tank, and control the start-up and shutdown status of the microporous aeration devices and mechanical stirring devices in the end area based on the selected operating mode. S4. Feedback Fine-tuning and Stable Operation: Continuously monitor the dissolved oxygen value at the end of the aerobic tank and the final effluent quality, compare the monitoring results with the target value, and adjust the microporous aeration device to ensure that the terminal DO is stable within the target range and the effluent quality meets the standards.

[0014] In a preferred embodiment, in step S1, the influent water quality parameters include chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) concentrations. The online instruments include an online influent water quality monitoring instrument installed in the influent pipeline, and online dissolved oxygen monitoring instruments installed at the front and rear of the aerobic tank.

[0015] In a preferred embodiment, in step S2, the condition for determining the high-load mode is that the concentration of pollutants in the influent is higher than a first set threshold; the condition for determining the normal-load mode is that the concentration of pollutants in the influent is between the first set threshold and the second set threshold; and the condition for determining the low-load mode is that the concentration of pollutants in the influent is lower than the second set threshold.

[0016] In a preferred embodiment, during the high-load mode, the influent pollutant concentration is higher than the first set threshold, including influent COD > 250 mg / L or influent NH3-N > 25 mg / L; during the normal-load mode, the influent pollutant concentration is between the first and second set thresholds, i.e., influent COD is in the range of 150-250 mg / L and influent NH3-N is in the range of 15-25 mg / L; the low-load mode is determined by influent COD < 150 mg / L or influent NH3-N < 15 mg / L.

[0017] In a preferred embodiment, in step S3, the operation method for controlling the start / stop status of the microporous aeration device and the mechanical stirring device in the terminal area based on the selected operating mode is as follows: In high-load mode, the microporous aeration devices are turned on in the front, middle and end sections of the aerobic tank, and the mechanical stirring device is turned on in the terminal area at the same time; in normal-load mode, the microporous aeration devices are turned on in the front, middle and end sections of the aerobic tank, and the mechanical stirring device is turned on intermittently in the terminal area; in low-load mode, the microporous aeration devices are turned on in the front and middle sections of the aerobic tank, the microporous aeration devices at the end of the aerobic tank are turned off, and only the mechanical stirring device is turned on.

[0018] In the preferred embodiment, in step S3, the gradual reduction aeration strategy is as follows: the aerobic tank is set up with front, middle and end sections, and the aerator arrangement density of the microporous aeration devices in the front, middle and end sections decreases sequentially.

[0019] In a preferred embodiment, the aerator arrangement density ratio of the microporous aeration device in the front, middle and end regions is 10:(7-8):(3-5).

[0020] In a preferred embodiment, in step S4, the control target for the high-load mode is to control the DO at the end of the aerobic tank at 1.6-2.0 mg / L; the control target for the normal-load mode is to control the DO at the end of the aerobic tank at 0.8-1.6 mg / L; and the control target for the low-load mode is to maintain the DO at the end of the aerobic tank at 0.3-0.5 mg / L.

[0021] In a preferred embodiment, step S4 includes the following steps: Step 1: Calculate the theoretical air supply GsL based on the influent water quality and quantity, and perform aeration through a microporous aeration device; Step 2: Calculate the decrease in DO at the end of the aerobic tank, ΔDO, over a set historical time period. Step 3: Adjust the blower opening according to ΔDO in stages until the DO at the end of the aerobic tank is controlled within the target range.

[0022] In the preferred embodiment, the formula for calculating the theoretical gas supply volume GsL is: ; in: Q This refers to the influent flow rate; COD in , TN in , Tp in These are the influent COD, influent TN, and influent TP, respectively. Bc For B / C; Y This is the sludge yield coefficient; T The reaction temperature; DO The current DO in the mixture; OTEFor oxygen transfer efficiency; TN o The effluent is TN.

[0023] In the preferred embodiment, in step 3, if ΔDO < 0.15 mg / L, the blower opening is fixed at 3%; when 0.15 ≤ ΔDO ≤ 0.3 mg / L, the blower opening adjustment is max{[( Gs L - Gs 0) / 420 / 4×5%],5%}, the maximum shall not exceed 10%; if ΔDO>0.3mg / L, the blower opening adjustment amount = max{[( Gs L - Gs 0) / 420 / 6×5%],3%}, with a maximum not exceeding 6%, where Gs0 is the current actual gas supply.

[0024] The present invention provides a coupled aeration-stirring operation method and operation procedure for aerobic tanks in wastewater treatment based on dynamic load control, which has the following beneficial effects: 1. This invention employs a gradually decreasing aeration design to match the oxygen demand gradient of wastewater degradation along the tank length, avoiding the energy waste caused by traditional uniform aeration. Combined with a coupling strategy of shutting down end-stage micro-pore aeration and only activating low-power mechanical stirring under low-load mode, it utilizes simultaneous nitrification and denitrification to naturally maintain low DO levels, significantly reducing aeration energy consumption. The intelligent control platform adjusts the blower opening in stages based on DO change trends, reducing ineffective air supply and further optimizing energy consumption.

[0025] 2. This invention uses influent COD and NH3-N concentrations as feedforward signals to dynamically switch between high, normal, and low operating modes, precisely controlling the final dissolved oxygen (DO). This satisfies the oxygen demand of biochemical reactions under different loads while avoiding the decrease in treatment efficiency caused by excessively high or low DO levels. Specifically, in low-load mode, DO is precisely maintained at 0.3-0.5 mg / L, effectively avoiding the risks of sludge settling and nitrification inhibition. Closed-loop control with zoned regulation and feedback fine-tuning ensures that the effluent NH3-N consistently meets the standard (<1.5 mg / L), significantly improving the removal efficiency of pollutants such as COD.

[0026] 3. This invention addresses the common problem in domestic wastewater treatment plants of "large design redundancy and actual influent load lower than design value." It covers a wide load range for influent COD from <150mg / L to >250mg / L and NH3-N from <15mg / L to >25mg / L, dynamically switching between three operating modes to adapt to different influent load fluctuations. This system is suitable for the initial design of newly built wastewater treatment plants and can also be applied to the renovation of existing wastewater treatment plants through aerator density adjustments, the addition of mixing devices, and upgrades to the automatic control system. It requires no major reconstruction of existing facilities, demonstrating strong adaptability and effectively solving the operational dilemma of "oversized equipment for undersized loads."

[0027] 4. The collaboration between online instruments and intelligent control platforms enables real-time monitoring, automatic regulation, and feedback fine-tuning, reducing manual intervention and lowering operation and maintenance costs. At the same time, the DO remains stable within the target range during system operation, and equipment start-up, shutdown, and adjustment are smooth, extending equipment lifespan and improving overall operational reliability. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a flowchart of the air volume adjustment process for a microporous aeration device under normal load conditions. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0030] Example 1: This embodiment provides an aeration-stirring coupled system for aerobic tanks in wastewater treatment based on dynamic load control. The system includes the following core components: 1. Wastewater treatment system: including an anaerobic tank, an anoxic tank and an aerobic tank connected in sequence. The aerobic tank is divided into three areas, namely the front section, the middle section and the end section, in a ratio of 4:3:3. This division ratio can accurately match the oxygen demand gradient distribution of pollutants in the wastewater as they are gradually degraded along the water flow direction.

[0031] 2. Gradual Decreasing Aeration System: This system includes microporous aeration devices arranged along the water flow direction in the aerobic tank. The aerator density of the microporous aeration devices decreases sequentially in the front, middle, and end sections, with a density ratio of 10:(7-8):(3-5). The aerator pore size and density of the microporous aeration devices are optimized based on a model relating air volume per unit aeration area to oxygen mass transfer efficiency. The calculation formula is: d=k1 (Q / (S θ))¹ / ³+k2; where d is the bubble diameter; (Q / (S θ) represents the air volume per unit aeration area, Q is the influent flow rate, and S is the aeration area; θ refers to the hydraulic retention time; k1 and k2 are coefficients obtained through experiments. Based on the varying properties of activated sludge mixed liquor in different wastewater treatment plants, k1 ranges from 1.3 to 1.5 × 10⁻⁶. 4; the value of k2 ranges from 1.4 to 1.6 × 10⁻⁶. 4.

[0032] 3. Mixing system: A mechanical mixing device is installed at the end of the aerobic tank. The mechanical mixing device is a large impeller low-power submersible mixer or a hyperboloid submersible mixer, with a power density of 3-10W / m³, preferably 5-8W / m³.

[0033] 4. Online instruments: At least online DO meters and mixed liquor suspended solids concentration meters shall be installed at the front, middle and end of the aerobic tank, and online water quality analyzers shall be installed at the inlet and outlet of the wastewater treatment system; among them, the online water quality monitoring instrument for the inlet pipeline and the online dissolved oxygen monitoring instrument for the front and end of the aerobic tank are the core monitoring equipment.

[0034] 5. Intelligent control platform: Receives data collected by online instruments, uses the influent pollutant load as the feedforward signal, and the DO at the end of the aerobic tank and the effluent water quality as feedback signals to dynamically regulate the start and stop of the microporous aeration device and the mechanical stirring device; the intelligent control platform is configured to execute three operating modes: high load mode, normal load mode, and low load mode.

[0035] Example 2: Based on Example 1, a method for coupled aeration-stirring operation of an aerobic tank in wastewater treatment based on dynamic load control is provided, including the following steps: S1. Real-time monitoring and load calculation: Influent water quality parameters are collected through online instruments, including chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) concentrations. The pollutant load of the current influent is calculated based on the collected parameters.

[0036] S2. Determine the load level and select the operating mode: Determine the load level based on the influent water quality parameters, and select the corresponding aeration-stirring coupled operating mode for the aerobic tank terminal area; where: The criteria for determining the high-load mode are that the concentration of pollutants in the influent is higher than the first set threshold, i.e., influent COD > 250 mg / L or influent NH3-N > 25 mg / L; The criteria for determining the normal load mode are that the concentration of pollutants in the influent is between the first and second set thresholds, that is, the influent COD is in the range of 150-250 mg / L and the influent NH3-N is in the range of 15-25 mg / L. The criteria for determining the low-load mode are that the concentration of pollutants in the influent is lower than the second set threshold, namely, influent COD < 150 mg / L or influent NH3-N < 15 mg / L.

[0037] S3. Implement zoned control and equipment start / stop: Implement a gradual reduction aeration strategy for the microporous aeration devices in the front, middle, and end sections of the aerobic tank, that is, adjust the aeration rate by successively decreasing the density of aerators in the front, middle, and end sections. Based on the selected operating mode, control the start / stop status of the microporous aeration devices and mechanical stirring devices in the end area. The control strategy is shown in the table below:

[0038] Specifically as follows: In high-load mode, the microporous aeration device and the mechanical stirring device are turned on simultaneously in the end area of ​​the aerobic tank; During normal load mode, the microporous aeration device is turned on at the end of the aerobic tank, and the mechanical stirring device is turned on intermittently. In low-load mode, turn off the microporous aeration device at the end of the aerobic tank and only turn on the mechanical stirring device.

[0039] In all three modes, the microporous aeration device is activated in both the front and middle sections of the aerobic tank without any adjustments.

[0040] S4. Feedback Fine-tuning and Stable Operation: Continuously monitor the dissolved oxygen (DO) value at the end of the aerobic tank and the final effluent quality. Compare the monitoring results with the target values ​​and adjust the microporous aeration device to ensure that the DO at the end is stable within the target range and the effluent quality meets the standards; among which: The target for terminal DO control in high-load mode is 1.6-2.0 mg / L; The target for terminal DO control under normal load conditions is 0.8-1.6 mg / L; The target for terminal DO control in low-load mode is 0.3-0.5 mg / L; The specific fine-tuning steps are as follows: Step 1: Calculate the theoretical air supply GsL based on the influent water quality and quantity, and perform aeration using a microporous aeration device; theoretical air supply... Gs L The calculation formula is: ; in: Q This refers to the influent flow rate; COD in , TN in , Tp in These are the influent COD, influent TN, and influent TP, respectively. Bc The ratio is B / C, where B refers to Biochemical Oxygen Demand (BOD) and C refers to Chemical Oxygen Demand (COD). Bc This is the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD), with a default value of 0.5. Y This is the sludge yield coefficient; T The reaction temperature; DO The current DO in the mixture; OTE For oxygen transfer efficiency; TN o The effluent is TN.

[0041] Step 2: Calculate the decrease in DO at the end of the aerobic tank, ΔDO, over a set historical time period. Step 3: Adjust the blower opening according to the ΔDO levels until the DO at the end of the aerobic tank is controlled within the target range, as shown in Table 2. Specifically, if ΔDO < 0.15 mg / L, adjust the blower opening by 3%; when 0.15 ≤ ΔDO ≤ 0.3 mg / L, the blower opening adjustment amount = max{[( Gs L - Gs 0) / 420 / 4×5%],5%}, the maximum shall not exceed 10%; if ΔDO>0.3mg / L, the blower opening adjustment amount = max{[( Gs L - Gs [0) / 420 / 6×5%],3%}, with a maximum not exceeding 6%, of which Gs 0 represents the current actual gas supply.

[0042]

[0043] Taking the normal load mode as an example, see the flowchart below. Figure 1 .

[0044] The control trigger condition is: when the online DO value is <0.8mg / L or >1.6mg / L, the system starts the air volume adjustment program.

[0045] The specific control logic and process are as follows: Step 1: Calculate the short-term trend of DO. After the adjustment is triggered, the system monitors the decrease in DO (ΔDO) over the past 40 minutes. 0-40min ): If ΔDO < 0.15 mg / L → slight fluctuation, fine-tune the airflow; if 0.15 ≤ ΔDO ≤ 0.3 mg / L → moderate change, moderate adjustment; if ΔDO > 0.3 mg / L → significant decrease, large adjustment.

[0046] Step 2: Calculate the theoretical gas supply.

[0047] Step 3: Determine the air volume adjustment range and adjust the blower opening according to ΔDO levels.

[0048] Step 4: Execution and Feedback Adjust the opening by only 1% each time, gradually approaching the target and avoiding drastic fluctuations; Continuous monitoring of DO after adjustment; Stop adjusting when DO returns to the range of 0.8–1.6 mg / L.

[0049] Example 3: This example illustrates the application of a newly built wastewater treatment plant.

[0050] (I) System Configuration A newly built 100,000-ton / day wastewater treatment plant adopts the aeration-stirring coupled system of the present invention, with the following specific configuration: The wastewater treatment system consists of anaerobic, anoxic, and aerobic tanks connected sequentially. The total effective volume of the aerobic tanks is 30,000 m³, divided into the first section (12,000 m³) and the second section (3,000 m³) in a 4:3:3 ratio. 3 ), middle section (9000 m) 3 ), end (9000 m) 3 ); Gradual aeration system: Microporous aeration devices are arranged along the water flow direction of the aerobic tank, with aeration densities of 9 devices / m³ at the front, middle, and end sections. 2 7 units / m 2 4 units / m 2 (Ratio 10:7.8:4.4, conforming to the range of 10:(7-8):(3-5)), the aerator orifice diameter is determined by the formula d=k1. (Q / (S θ)) 1 / 3 +k2 optimization calculation, where k1 is taken as 1.4×10 4 k2 is taken as 1.5 × 10 4 Q is 100,000 tons / day, S is the aeration area of ​​the aerobic tank, and θ is the hydraulic retention time of 8 hours. Mixing system: Six large-impeller, low-power submersible mixers with a power density of 6W / m³ are installed at the end of the aerobic tank (between 3-10W / m³). 3 Preferred range: 5-8 W / m 3 Inside); Online instruments: One online DO meter and one mixed liquor suspended solids concentration meter are installed at the front, middle and end of the aerobic tank. One online influent water quality monitoring instrument (monitoring COD and NH3-N) is installed on the influent pipeline, and one online water quality analyzer is installed at the outlet. Intelligent control platform: Signal connection to all online instruments and equipment, configured with control logic for three operating modes: high, normal, and low.

[0051] (II) Operation Process The wastewater treatment plant has an actual influent average COD of 180 mg / L and NH3-N of 18 mg / L, which falls under the conventional load mode. The operating process is as follows: S1 Real-time Monitoring and Load Calculation: The influent water quality is monitored in real time by the online monitoring instrument, which collects COD=182mg / L and NH3-N=17.5mg / L. Combined with the influent flow rate of 100,000 tons / day, the current influent pollutant load is calculated. S2 Load Level Judgment and Mode Selection: Based on monitoring data, COD is in the range of 150-250 mg / L and NH3-N is in the range of 15-25 mg / L, so it is judged as a normal load mode, and the terminal DO control target is set at 1.2 mg / L; S3 Zone Control and Equipment Start-up / Stop: Gradually reduce aeration in the front, middle and end sections, and adjust the aeration volume according to the preset density ratio; activate the microporous aeration device in the end area and intermittently activate the mechanical stirring device (pause for 10 minutes every 30 minutes of operation). S4 Feedback Fine-tuning and Stable Operation: Continuously monitor the terminal DO value and calculate the DO decrease over the past 40 minutes ΔDO = 0.2 mg / L (between 0.15-0.3 mg / L). Calculate the theoretical air supply using the formula, and obtain the blower opening adjustment amount = max{[(GsL-14000) / 420 / 4×5%],5%} = 6%. Adjust the blower opening according to this amount, and the terminal DO will eventually stabilize at 1.2 ± 0.1 mg / L.

[0052] (III) Operational Results After the newly built plant was operated using the method of this invention, the terminal DO was stably controlled within the target range, with COD ≤ 40 mg / L and NH3-N ≤ 1.5 mg / L in the effluent, meeting the Class A discharge standard. Compared with the traditional uniform aeration mode, the aeration energy consumption was reduced by 22%, saving an average of about 3,200 yuan in electricity costs per day.

[0053] Example 4: This embodiment illustrates the application of retrofitting existing wastewater treatment plants.

[0054] (I) Renovation Plan A wastewater treatment plant with a capacity of 50,000 tons / day originally had an aerobic tank with a uniform aeration design, which resulted in excessive aeration energy consumption. This invention was used for the renovation, and the renovation details are as follows: Aerobic tank zoning: The original aerobic tank is divided into front section, middle section and end section in a 4:3:3 ratio, and the zoned water flow is achieved by setting up guide walls; Modification of the gradual reduction aeration system: Adjust the arrangement density of the original microporous aeration devices. Maintain the original density at the front (8 aerators / m²), remove 30% of the aerators in the middle section (density 5.6 aerators / m²), and remove 55% of the aerators at the end (density 3.6 aerators / m²), forming a density ratio of 10:7:4.5 (within the range of 10:(7-8):(3-5)); adjust the aerator pore size according to the optimized formula, with k1 set to 1.35 × 10⁻⁶. 4. k2 is taken as 1.45 × 10 4; New mixing system: Four hyperboloid submersible mixers with a power density of 5W / m³ were added to the end area of ​​the aerobic tank; Online instrumentation upgrade: Online DO meters were added at the front and end of the aerobic tank, and online COD and NH3-N monitors were added at the inlet. The intelligent control platform was upgraded and control programs for three operating modes were added.

[0055] (II) Operation Process After the renovation, the influent load of the wastewater treatment plant fluctuated significantly. At one time, the influent COD was 280 mg / L and NH3-N was 27 mg / L (high load mode), while at another time, the influent COD was 130 mg / L and NH3-N was 12 mg / L (low load mode). The operating process is as follows: High load mode operation: S1: Monitoring of influent COD=280mg / L, NH3-N=27mg / L, influent flow rate 50,000 tons / day; S2: Determined to be in high-load mode, terminal DO control target set at 1.8 mg / L; S3: The front, middle and end sections are supplied with air according to the gradually decreasing aeration strategy, and the microporous aeration device and mechanical stirring device are turned on at the end. S4: The monitoring terminal DO decrease ΔDO=0.35mg / L (>0.3mg / L), the theoretical gas supply GsL=50000×(R-AY) / (0.28×OTE), the current Gs0=8000m³ / h, the blower opening adjustment amount=max{[(GsL-8000) / 420 / 6×5%],3%}=5%, after adjustment the terminal DO stabilizes at 1.8mg / L, the effluent COD=45mg / L, NH3-N=1.2mg / L.

[0056] Low load mode operation: S1: Monitoring of influent COD=130mg / L, NH3-N=12mg / L, influent flow rate 50,000 tons / day; S2: Determined to be in low-load mode, the terminal DO control target is set to 0.4 mg / L; S3: The front and middle sections are supplied with air according to the gradually decreasing aeration strategy, and the microporous aeration device is closed at the end, with only the mechanical stirring device turned on. S4: At the monitoring terminal, DO=0.42mg / L, ΔDO=0.12mg / L (<0.15mg / L), no need to adjust the blower opening, DO is stable between 0.38-0.43mg / L, effluent COD=38mg / L, NH3-N=1.0mg / L.

[0057] (III) Operational Results After the renovation, the existing wastewater treatment plant improved pollutant removal efficiency by 12% during high-load periods, reduced aeration energy consumption by 38% during low-load periods, and reduced energy consumption by 25% during normal-load periods. Before the renovation, the total power of the blowers was 450kW, while after the renovation, the blower power was 360kW during high-load periods and only 280kW during low-load periods. The total power of the newly added mixer was 20kW, resulting in an overall reduction of 18%-30% in total power consumption and annual energy cost savings of approximately 1.2 million yuan. At the same time, the stability of the effluent water quality was significantly improved.

[0058] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A coupled aeration-stirring system for an aerobic tank in wastewater treatment based on dynamic load control, characterized in that, include: The wastewater treatment system includes an anaerobic tank, an anoxic tank, and an aerobic tank connected in sequence. The aerobic tank is divided into three areas: a front section, a middle section, and a terminal section. The gradual reduction aeration system includes microporous aeration devices arranged along the water flow direction of the aerobic tank; A mixing system is provided, with a mechanical mixing device installed at the end of the aerobic tank. Online instruments: At least online DO meters and mixed liquor suspended solids concentration meters should be installed at the front, middle and end of the aerobic tank, and online water quality analyzers should be installed at the inlet and outlet of the wastewater treatment system; Intelligent control platform: Receives data from the detection system, uses the influent pollutant load as the feedforward signal and the DO at the end of the aerobic tank and the effluent water quality as feedback signals, and dynamically regulates the start and stop of the microporous aeration device and the mechanical stirring device.

2. The aeration-stirring coupled system for aerobic tanks in wastewater treatment based on dynamic load control according to claim 1, characterized in that, The aerobic tank is divided into a front section, a middle section, and an end section in a 4:3:3 ratio.

3. The aeration-stirring coupled system for aerobic tanks in wastewater treatment based on dynamic load control according to claim 1, characterized in that, In the gradually decreasing aeration system, the aerator arrangement density of the microporous aeration device decreases sequentially in the front, middle and end sections.

4. The aeration-stirring coupled system for aerobic tanks in wastewater treatment based on dynamic load control according to claim 1, characterized in that, In the decreasing aeration system, the aerator pore size and arrangement density of the microporous aeration device are optimized based on a model relating air volume per unit aeration area to oxygen mass transfer efficiency. The calculation formula is as follows: d=k1 (Q / (S θ))¹ / ³+k2; Where d is the bubble diameter; Q / (S θ) represents the air volume per unit aeration area, Q is the influent flow rate, and S is the aeration area; θ refers to the hydraulic retention time; k1 and k2 are coefficients obtained through experiments. Based on the varying properties of activated sludge mixed liquor from different wastewater treatment plants, k1 ranges from 1.3 to 1.5 × 10⁻⁶. 4 The value of k2 ranges from 1.4 to 1.6 × 10⁻⁶. 4 .

5. The aeration-stirring coupled system for aerobic tanks in wastewater treatment based on dynamic load control according to claim 1, characterized in that, The intelligent control platform is configured to execute one of the following operating modes: High-load mode: When the concentration of pollutants in the influent exceeds the first set threshold, the microporous aeration device is activated in the front, middle and terminal sections, the mechanical stirring device is activated at the same time, and the DO at the terminal is controlled at 1.6-2.5 mg / L. Normal load mode: When the influent pollutant concentration is between the first and second set thresholds, the microporous aeration devices are turned on in the front, middle and end sections, and the mechanical stirring device can be turned on intermittently to control the terminal DO at 0.8-1.6 mg / L. Low load mode: When the concentration of pollutants in the influent is lower than the second set threshold, the microporous aeration device is turned on in the front and middle sections and turned off in the terminal section. The mechanical stirring device is turned on to control the terminal DO to be maintained at 0.3-0.5 mg / L.

6. A method for coupled aeration-stirring operation of an aerobic tank in wastewater treatment based on dynamic load control according to claim 1, characterized in that, Includes the following steps: S1. Real-time monitoring and load calculation: Influent water quality parameters are collected through online instruments; S2. Determine the load level and select the operating mode: Determine the load level based on the influent water quality parameters, and select the corresponding aeration-stirring coupled operating mode for the end area of ​​the aerobic tank. The operating modes include high load mode, normal load mode and low load mode. S3. Implement zoned control and equipment start-up and shutdown: Implement a gradual reduction aeration strategy for the microporous aeration devices in the front, middle and end sections of the aerobic tank, and control the start-up and shutdown status of the microporous aeration devices and mechanical stirring devices in the end area based on the selected operating mode. S4. Feedback Fine-tuning and Stable Operation: Continuously monitor the dissolved oxygen value at the end of the aerobic tank and the final effluent quality, compare the monitoring results with the target value, and adjust the microporous aeration device to ensure that the terminal DO is stable within the target range and the effluent quality meets the standards.

7. The aeration-stirring coupled operation method for aerobic tanks in wastewater treatment based on dynamic load control according to claim 6, characterized in that, In step S1, the influent water quality parameters include chemical oxygen demand (COD) and ammonia nitrogen (NH3-N). The online instruments include an online influent water quality monitoring instrument installed in the influent pipeline, and online dissolved oxygen monitoring instruments installed at the front and end of the aerobic tank.

8. The aeration-stirring coupled operation method for aerobic tanks in wastewater treatment based on dynamic load control according to claim 6, characterized in that, In step S2, the judgment condition for the high load mode is that the concentration of pollutants in the influent is higher than the first set threshold; the judgment condition for the normal load mode is that the concentration of pollutants in the influent is between the first set threshold and the second set threshold; and the judgment condition for the low load mode is that the concentration of pollutants in the influent is lower than the second set threshold.

9. A method for coupled aeration-stirring operation of an aerobic tank in wastewater treatment based on dynamic load control, as described in claim 6, is characterized in that... In the high-load mode, the influent pollutant concentration is higher than the first set threshold, including influent COD > 250 mg / L or influent NH3-N > 25 mg / L; in the normal-load mode, the influent pollutant concentration is between the first and second set thresholds, i.e., influent COD is in the range of 150-250 mg / L and influent NH3-N is in the range of 15-25 mg / L; the low-load mode is determined by influent COD < 150 mg / L or influent NH3-N < 15 mg / L.

10. A method for coupled aeration-stirring operation of an aerobic tank in wastewater treatment based on dynamic load control, as described in claim 6, is characterized in that... In step S3, based on the selected operating mode, the operation method for controlling the start and stop status of the microporous aeration device and the mechanical stirring device in the terminal area is as follows: In high-load mode, the microporous aeration devices are turned on in the front, middle and end sections of the aerobic tank, and the mechanical stirring device is turned on in the terminal area at the same time; In normal-load mode, the microporous aeration devices are turned on in the front, middle and end sections of the aerobic tank, and the mechanical stirring device is turned on intermittently in the terminal area; In low-load mode, the microporous aeration devices are turned on in the front and middle sections of the aerobic tank, the microporous aeration devices at the end of the aerobic tank are turned off, and only the mechanical stirring device is turned on.

11. The aeration-stirring coupled operation method for aerobic tanks in wastewater treatment based on dynamic load control according to claim 6, characterized in that, In step S3, the gradual reduction aeration strategy is as follows: the aerobic tank is set up with front, middle and end sections, and the aerator arrangement density of the microporous aeration device in the front, middle and end sections decreases sequentially.

12. The aeration-stirring coupled operation method for aerobic tanks in wastewater treatment based on dynamic load control according to claim 6, characterized in that, The aerator arrangement density ratio of the microporous aeration device in the front, middle and end regions is 10:(7-8):(3-5).

13. The aeration-stirring coupled operation method for aerobic tanks in wastewater treatment based on dynamic load control according to claim 6, characterized in that, In step S4, the control target for the high-load mode is to control the DO at the end of the aerobic tank at 1.6-2.0 mg / L; the control target for the normal-load mode is to control the DO at the end of the aerobic tank at 0.8-1.6 mg / L; and the control target for the low-load mode is to maintain the DO at the end of the aerobic tank at 0.3-0.5 mg / L.

14. The aeration-stirring coupled operation method for aerobic tanks in wastewater treatment based on dynamic load control according to claim 6, characterized in that, Step S4 includes the following steps: Step 1: Calculate the theoretical air supply GsL based on the influent water quality and quantity, and perform aeration through a microporous aeration device; Step 2: Calculate the decrease in DO at the end of the aerobic tank, ΔDO, over a set historical time period. Step 3: Adjust the blower opening according to ΔDO in stages until the DO at the end of the aerobic tank is controlled within the target range.

15. A method for coupled aeration-stirring operation of an aerobic tank in wastewater treatment based on dynamic load control, as described in claim 14, is characterized in that... The theoretical gas supply Gs L The calculation formula is: ； in: Q This refers to the influent flow rate; COD in , TN in , Tp in These are the influent COD, influent TN, and influent TP, respectively. Bc For B / C; Y This is the sludge yield coefficient; T The reaction temperature; DO The current DO in the mixture; OTE For oxygen transfer efficiency; TN o The effluent is TN.

16. The aeration-stirring coupled operation method for aerobic tanks in wastewater treatment based on dynamic load control according to claim 14, characterized in that, In step 3, if ΔDO < 0.15 mg / L, the blower opening is fixed at 3%. When 0.15≤ΔDO≤0.3mg / L, the blower opening adjustment amount = max{[( Gs L - Gs 0) / 420 / 4×5%],5%}, the maximum shall not exceed 10%; if ΔDO>0.3mg / L, the blower opening adjustment amount = max{[( Gs L - Gs 0) / 420 / 6×5%],3%}, with a maximum not exceeding 6%, where Gs0 is the current actual gas supply.

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