Automatic control system for internal and external backflow in sewage treatment

Abstract

The invention relates to the technical field of sewage treatment, in particular to an internal and external backflow automatic control system for sewage treatment. The system comprises an internal reflux system and an external reflux system, and the internal reflux system adjusts the frequency of internal reflux pumps or the number of started internal reflux pumps by monitoring the change of water quality parameters such as nitrate nitrogen, nitrite nitrogen, ammonia nitrogen and dissolved oxygen so as to maintain the balance of nitrification and denitrification reactions; and the external reflux system adjusts the flow of an external reflux pump by monitoring the sludge concentration and the sludge level height so as to maintain the concentration and activity of microorganisms in the biological reaction tank. Besides, the system also adopts a mathematical model, a feedforward control strategy and a feedback control module, so that the response speed and the stability of the system are improved, the effective treatment of sewage is ensured, and the overall treatment efficiency and the effluent quality are improved.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and in particular to an automatic control system for internal and external reflux of sewage treatment. Background Art

[0002] Sewage treatment is an important part of environmental protection. With the acceleration of urbanization and the advancement of industrial development, the demand for sewage treatment is increasing. Traditional sewage treatment methods mainly rely on manual operation and experience judgment, and have problems such as low efficiency, high energy consumption and unstable treatment effect. In recent years, automatic control technology has been gradually applied to the field of sewage treatment, which has significantly improved the efficiency and stability of sewage treatment, reduced operating costs, and improved environmental quality.

[0003] In the sewage treatment process, the reasonable control of the internal and external reflow systems is essential to maintain the balance of nitrification and denitrification reactions. Existing solutions mainly include the following aspects: Water quality parameter monitoring: By installing ammonia nitrogen sensors, nitrate nitrogen sensors and other equipment, water quality parameters such as ammonia nitrogen (NH3-N), nitrate nitrogen (NO3⁻-N) and dissolved oxygen (DO) are monitored in real time at key locations. These parameters reflect the degree of nitrification and denitrification reactions, thereby guiding the adjustment of the working state of the internal reflow pump. Manual adjustment: The traditional method mainly relies on the experience of the operator to manually adjust the frequency or number of internal reflow pumps according to the test results. Although this method is simple and easy, due to the lack of real-time feedback and precise control, it is easy to lead to untimely or inadequate regulation, affecting the treatment effect.

[0004] Therefore, there is an urgent need for a control system that can provide real-time feedback based on water quality parameters and automatically adjust the working state of the internal reflux pump to improve the efficiency and stability of sewage treatment. Summary of the invention

[0005] The purpose of this application is to overcome the above technical problems and provide an automatic control system for internal and external reflux of sewage treatment An automatic control system for internal and external reflux of sewage treatment, comprising: The internal recirculation system is used to control the working status of the internal recirculation pump according to the feedback of water quality parameters. Specifically, by monitoring the changes of water quality parameters such as nitrate nitrogen (NO3⁻-N), nitrite nitrogen (NO2⁻-N), ammonia nitrogen (NH3-N) and dissolved oxygen (DO), the frequency or number of internal recirculation pumps opened is adjusted to maintain the balance of nitrification and denitrification reactions; The external reflow system is used to control the working status of the external reflow pump according to the feedback of the microbial concentration and activity and the operating status of the secondary sedimentation tank. Specifically, by monitoring the sludge concentration (MLSS) or volatile sludge concentration (MLVSS) and the mud level, the flow rate of the external reflow pump is adjusted to maintain the microbial concentration and activity in the biological reaction tank.

[0006] By adopting the above technical solutions, the internal reflow system can automatically adjust the working state of the internal reflow pump according to the real-time changes in water quality parameters, thereby accurately controlling the balance of nitrification and denitrification reactions and improving the sewage treatment effect and stability. The external reflow system can dynamically adjust the flow of the external reflow pump according to the changes in microbial concentration and activity and the operating conditions of the secondary sedimentation tank, effectively maintain the microbial concentration and activity in the biological reactor, and ensure the efficient operation of the system and sludge management.

[0007] Preferably, the internal reflux system comprises: Online water quality monitoring equipment, installed at key locations, is used to monitor water quality parameters such as ammonia nitrogen and nitrate nitrogen in real time; The controller is connected to the online water quality monitoring equipment and is used to adjust the speed or number of internal reflux pumps according to the preset water quality target value. When the concentration of ammonia nitrogen or nitrate nitrogen is detected to deviate from the target range, the controller automatically adjusts the speed or number of internal reflux pumps to restore the water quality to the set range as soon as possible.

[0008] By adopting the above technical solution, water quality parameters such as ammonia nitrogen and nitrate nitrogen can be monitored in real time, and the speed or number of internal reflux pumps can be automatically adjusted according to the preset water quality target values. This can quickly respond to water quality changes and ensure that water quality parameters always remain within the set range, thereby effectively maintaining the balance of nitrification and denitrification reactions and improving sewage treatment effects.

[0009] Preferably, the controller further includes: The mathematical model module is used to establish a mathematical model between water quality parameters and internal reflow flow, and to correct the model parameters through feedback from historical data and real-time monitoring data. The historical data and real-time monitoring data are used to continuously optimize the model parameters and improve the accuracy and timeliness of control.

[0010] By adopting the above technical solutions, the mathematical model module can continuously optimize the mathematical model between water quality parameters and internal reflow flow based on historical data and real-time monitoring data, thereby improving the accuracy and timeliness of internal reflow control. This helps to more accurately adjust the working state of the internal reflow pump, ensure the balance of nitrification and denitrification reactions, and improve the sewage treatment effect.

[0011] Preferably, the flow feedforward control strategy of the internal reflux system includes: Flow meter, installed on the water inlet pipe, used to monitor the water inlet flow in real time; The feedforward controller is connected to the flow meter and is used to predict and adjust the output flow of the internal reflux pump in advance according to the change of the inlet flow. When the inlet flow increases, the feedforward controller increases the output flow of the internal reflux pump in advance; when the inlet flow decreases, the feedforward controller reduces the output flow of the internal reflux pump accordingly to ensure the denitrification effect of the system.

[0012] By adopting the above technical solution, the flow feedforward control strategy of the internal reflow system can predict and adjust the output flow of the internal reflow pump in advance according to the change of the inlet flow. When the inlet flow increases, the feedforward controller increases the output flow of the internal reflow pump in advance to ensure that sufficient nitrification liquid flows back to the anoxic zone to maintain the denitrification effect of the system; when the inlet flow decreases, the feedforward controller reduces the output flow of the internal reflow pump accordingly to avoid energy waste and hydraulic shock caused by excessive backflow. This feedforward control strategy improves the accuracy and timeliness of the internal reflow control, thereby better adapting to changes in the sewage inlet flow and improving the overall efficiency and stability of sewage treatment.

[0013] Preferably, the external reflux system comprises: Microbial concentration monitoring equipment, installed in the biochemical reaction tank and the secondary sedimentation tank, is used to monitor the sludge concentration (MLSS) or volatile sludge concentration (MLVSS) in real time; The controller is connected to the microbial concentration monitoring equipment and is used to adjust the flow of the external return pump according to the preset target sludge concentration range. When the MLSS or MLVSS is lower than the preset lower limit, the controller automatically increases the flow of the external return pump; when the MLSS or MLVSS is higher than the preset upper limit, the controller automatically reduces the flow of the external return pump to maintain the microbial concentration within an appropriate range.

[0014] By adopting the above technical solution, the external return system can monitor the sludge concentration of the biochemical reaction tank and the secondary sedimentation tank in real time, and automatically adjust the flow of the external return pump according to the preset target sludge concentration range. When MLSS or MLVSS is lower than the preset lower limit, the controller automatically increases the flow of the external return pump, thereby quickly replenishing the amount of microorganisms in the biological reaction tank to prevent the treatment effect from decreasing; when MLSS or MLVSS is higher than the preset upper limit, the controller automatically reduces the flow of the external return pump to avoid sludge aging and deterioration of sedimentation performance caused by excessive microbial concentration, thereby ensuring the stable operation of the system and efficient treatment effect.

[0015] Preferably, the controller further includes: The mud level monitoring device is installed in the secondary sedimentation tank to monitor the mud level height of the secondary sedimentation tank; The dynamic compensation module is used to dynamically adjust the external reflow ratio according to the mud level and other operating parameters. When the mud level is too high, the dynamic compensation module increases the external reflow ratio to lower the mud level; when the mud level is too low, the dynamic compensation module reduces the external reflow ratio to save energy and maintain stable operation of the system.

[0016] By adopting the above technical solution, the dynamic compensation module can adjust the external return ratio in real time according to the mud level height and other operating parameters of the secondary sedimentation tank. When the mud level is too high, increasing the external return ratio can effectively reduce the mud level and prevent sludge loss; when the mud level is too low, reducing the external return ratio can save energy and maintain stable operation of the system. This dynamic adjustment method improves the flexibility and adaptability of the system, ensuring that the sludge concentration and mud level height are always in the best state during the sewage treatment process, thereby improving the overall treatment effect and energy efficiency.

[0017] Preferably, the flow feedforward compensation control strategy of the external reflux system includes: The water inlet flow meter is installed on the water inlet pipe to monitor the water inlet flow in real time; The compensation controller is connected to the water inlet flow meter and is used to adjust the speed of the external return pump or the number of pumps turned on according to the change of the water inlet flow. When the water inlet flow increases, the compensation controller increases the speed of the external return pump in advance or turns on more pumps; when the water inlet flow decreases, the compensation controller reduces the speed of the external return pump or shuts down some pumps accordingly to prevent excessive dilution of the sludge concentration in the reaction tank.

[0018] By adopting the above technical solution, the flow feedforward compensation control strategy of the external return system can monitor the changes in the inlet flow in real time, and adjust the speed or number of external return pumps in advance according to the changes. When the inlet flow increases, the compensation controller increases the speed of the external return pump or opens more units in advance to prevent excessive dilution of the sludge concentration in the reaction tank, ensuring that the concentration and activity of microorganisms in the biological reaction tank are maintained within an appropriate range, thereby improving the sewage treatment effect. When the inlet flow decreases, the compensation controller reduces the speed of the external return pump or shuts down some pumps accordingly to avoid unnecessary energy waste and maintenance costs, while ensuring the stable operation of the system.

[0019] Preferably, the nitrogen balance feedback control of the internal reflux system includes: The nitrate nitrogen generation calculation module is used to calculate the actual nitrate nitrogen generation according to the inlet ammonia nitrogen concentration (IN_NH3-N), the effluent ammonia nitrogen concentration (OUT_NH3-N), the nitrate nitrogen concentration at the end of the aerobic pool (NO3⁻-N_O) and the nitrate nitrogen concentration at the inlet of the anoxic pool (NO3⁻-N_A), using the formula R = (NO3⁻-N_O - NO3⁻-N_A) / NO3⁻-N_A * 100%, where R is the internal reflux ratio; The denitrification removal calculation module is used to calculate the amount of nitrate nitrogen removed by denitrification based on the above concentration parameters, using the formula QR = QIN * R, where QR is the internal reflow flow rate and QIN is the influent flow rate; The adjustment module is used to adjust the internal reflux ratio according to the deviation of the actual nitrate nitrogen concentration from the target range. When the actual nitrate nitrogen concentration deviates from the target range, the adjustment module adjusts the internal reflux ratio according to the deviation to restore it to the target range.

[0020] By adopting the above technical solution, the nitrogen balance feedback control of the internal recirculation system can calculate the actual nitrate nitrogen generation and denitrification removal in real time based on the inlet ammonia nitrogen concentration, the effluent ammonia nitrogen concentration, the nitrate nitrogen concentration at the end of the aerobic tank and the nitrate nitrogen concentration at the inlet of the anoxic tank. When the actual nitrate nitrogen concentration deviates from the target range, the system automatically adjusts the internal recirculation ratio to quickly restore the nitrate nitrogen concentration to the set range, thereby ensuring the efficient and stable operation of nitrification and denitrification reactions during sewage treatment.

[0021] Preferably, the sludge balance feedback control of the external reflow system includes: The biological reactor mixed liquor sludge concentration calculation module is used to calculate the sludge growth according to the mixed liquor sludge concentration of the biochemical reactor (MLSSR), the sludge concentration of the secondary sedimentation tank (MLSSS) and the influent flow (QIN), using the formula RE = (MLSSR - MLSSS) / MLSSS * 100%, where RE is the external reflow ratio; The target sludge concentration setting module is used to set the target sludge concentration range in the biochemical reaction tank, and the target sludge concentration range is determined according to the treatment process and water quality requirements; The adjustment module is used to adjust the external reflow ratio according to the deviation of the actual sludge concentration from the target range. When the actual sludge concentration deviates from the target range, the adjustment module adjusts the external reflow ratio according to the deviation to restore it to the target range.

[0022] By adopting the above technical solutions, precise control of the external reflow system can be achieved to ensure that the concentration of microorganisms in the biochemical reaction tank is always in the best state. Specifically, the mixed liquor sludge concentration calculation module of the biological reaction tank can monitor and calculate the sludge growth in real time, the target sludge concentration setting module sets a reasonable sludge concentration range according to the treatment process and water quality requirements, and the adjustment module automatically adjusts the external reflow ratio according to the deviation of the actual sludge concentration, thereby effectively maintaining the stability of the system and the treatment effect. This closed-loop control method not only improves the efficiency and reliability of sewage treatment, but also reduces energy consumption and operating costs.

[0023] Preferably, the flow feedforward compensation control of the external reflux system further includes: An empirical relationship database stores the empirical relationship between the inlet flow rate and the external return flow rate under different working conditions; The proportional coefficient dynamic adjustment module is used to dynamically adjust the proportional coefficient K according to the real-time monitored water inlet flow and empirical relationship. When the water inlet flow changes, the proportional coefficient dynamic adjustment module adjusts the value of K according to experience and current working conditions, and then uses the formula QRE = K * QIN to calculate the external return flow.

[0024] By adopting the above technical solution, the flow feedforward compensation control of the external return system can dynamically adjust the flow of the external return pump according to different influent flow rates, ensuring that the concentration of microorganisms in the biological reactor is always in the optimal state. Specifically, when the influent flow rate increases, the system will increase the output flow of the external return pump in advance to prevent the sludge from being diluted and ensure that enough microorganisms participate in the treatment process; and when the influent flow rate decreases, the output flow of the external return pump is reduced accordingly to avoid unnecessary energy waste and sludge loss. This intelligent control method not only improves the efficiency and stability of sewage treatment, but also significantly reduces operating costs.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. It realizes real-time feedback control based on water quality parameters. By monitoring the changes of parameters such as nitrate nitrogen, nitrite nitrogen, ammonia nitrogen and dissolved oxygen, it automatically adjusts the frequency or number of internal reflux pumps to effectively maintain the balance of nitrification and denitrification reactions, thereby improving the treatment effect and system stability; 2. A flow feedforward control strategy was introduced to predict and adjust the output flow of the internal reflux pump in advance according to the change of the inlet flow, ensuring that a stable denitrification effect can be maintained when the inlet flow fluctuates, avoiding energy waste and hydraulic shock caused by flow changes; 3. Combined with the feedback control of the secondary sedimentation tank operation status and microbial concentration, the flow of the external return pump is automatically adjusted by monitoring the sludge concentration and mud level to maintain the microbial concentration and activity in the biological reaction tank, prevent sludge aging and deterioration of sedimentation performance, and ensure the long-term stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a principle block diagram of the automatic control system for internal and external reflow of sewage treatment in Example 1 of the present application.

[0027] Figure 2 This is a schematic diagram of the automatic control system for internal and external reflux of sewage treatment in Example 2 of the present application. DETAILED DESCRIPTION The following is combined with Figure 1-Figure 2 This application is described in further detail.

[0028] Embodiment 1: Reference Figure 1, the sewage treatment internal and external reflow automatic control system provided in the embodiment of the present application includes an internal reflow system and an external reflow system. The internal reflow system is used to control the working state of the internal reflow pump according to the feedback of water quality parameters, specifically by monitoring the changes of water quality parameters such as nitrate nitrogen (NO3⁻-N), nitrite nitrogen (NO2⁻-N), ammonia nitrogen (NH3-N) and dissolved oxygen (DO), and adjusting the frequency or number of internal reflow pumps to maintain the balance of nitrification and denitrification reactions; the external reflow system is used to control the working state of the external reflow pump according to the feedback of microbial concentration and activity and the operating status of the secondary sedimentation tank, specifically by monitoring the sludge concentration (MLSS) or volatile sludge concentration (MLVSS) and mud level, and adjusting the flow of the external reflow pump to maintain the concentration and activity of microorganisms in the biological reaction tank.

[0029] Specifically, the internal reflow system includes online water quality monitoring equipment and controllers. The online water quality monitoring equipment is set at key locations to monitor water quality parameters such as ammonia nitrogen and nitrate nitrogen in real time. For example, a nitrate nitrogen sensor can be installed at the outlet of the aerobic pool, and an ammonia nitrogen sensor can be installed at the entrance of the anoxic pool. These sensors can be electrochemical sensors or optical sensors with high sensitivity and long-term stability. In addition, a dissolved oxygen probe can be installed inside the aerobic pool to more fully understand the status of the nitrification reaction.

[0030] The controller is connected to the online water quality monitoring equipment to adjust the speed or number of internal reflow pumps according to the preset water quality target value. When the concentration of ammonia nitrogen or nitrate nitrogen is detected to deviate from the target range, the controller automatically adjusts the speed or number of internal reflow pumps to restore the water quality to the set range as soon as possible. For example, when the nitrate nitrogen concentration at the outlet of the aerobic pool increases, the controller will increase the frequency of the internal reflow pump or turn on more internal reflow pumps to transport more nitrate nitrogen to the anoxic pool for denitrification. On the contrary, if the nitrate nitrogen concentration is low, the internal reflow ratio will be appropriately reduced to avoid excessive reflow, resulting in energy waste and adverse effects on the anoxic pool environment.

[0031] In addition, the controller also includes a mathematical model module, which is used to establish a mathematical model between water quality parameters and internal reflow flow, and to correct the model parameters through feedback from historical data and real-time monitoring data. For example, by collecting historical data for one month, the relationship between nitrate nitrogen concentration and internal reflow flow can be analyzed to establish a preliminary mathematical model. Then, combined with real-time monitoring data, the model parameters are continuously optimized to improve the accuracy and timeliness of control.

[0032] The flow feedforward control strategy of the internal recirculation system is also very important. The flow meter is installed on the water inlet pipe to monitor the water inlet flow in real time. The feedforward controller is connected to the flow meter to predict and adjust the output flow of the internal recirculation pump in advance according to the change of the water inlet flow. When the water inlet flow increases, the feedforward controller increases the output flow of the internal recirculation pump in advance; when the water inlet flow decreases, the feedforward controller reduces the output flow of the internal recirculation pump accordingly to ensure the denitrification effect of the system.

[0033] The external reflow system includes a microbial concentration monitoring device and a controller. The microbial concentration monitoring device is installed in the biochemical reaction tank and the secondary sedimentation tank to monitor the sludge concentration (MLSS) or volatile sludge concentration (MLVSS) in real time. For example, a suspended solids concentration meter can be installed at the front end of the biochemical reaction tank and the middle of the secondary sedimentation tank to regularly sample and measure MLSS and MLVSS. These instruments can use ultrasonic sensors or infrared spectrum sensors with high accuracy and reliability.

[0034] The controller is connected to the microbial concentration monitoring device to adjust the flow of the external return pump according to the preset target sludge concentration range. When the MLSS or MLVSS is lower than the preset lower limit, the controller automatically increases the flow of the external return pump; when the MLSS or MLVSS is higher than the preset upper limit, the controller automatically reduces the flow of the external return pump to maintain the microbial concentration within the appropriate range. For example, when it is found that the MLSS is lower than 3000 mg / L, the controller will increase the flow of the external return pump to replenish the amount of microorganisms; when the MLSS exceeds 5000 mg / L, the controller will reduce the flow of the external return pump to avoid sludge aging and decreased sedimentation performance.

[0035] In addition, the controller also includes a mud level monitoring device and a dynamic compensation module. The mud level monitoring device is set in the secondary sedimentation tank to monitor the mud level height of the secondary sedimentation tank. The dynamic compensation module dynamically adjusts the external reflow ratio according to the mud level height and other operating parameters. When the mud level is too high, the dynamic compensation module increases the external reflow ratio to reduce the mud level; when the mud level is too low, the dynamic compensation module reduces the external reflow ratio to save energy and maintain stable operation of the system. For example, when the mud level reaches the warning line, the dynamic compensation module will immediately increase the external reflow ratio and quickly reduce the mud level; when the mud level is lower than the safety line, the dynamic compensation module will reduce the external reflow ratio to save energy.

[0036] The flow feedforward compensation control strategy of the external return system is also very critical. The inlet flow meter is installed on the inlet pipe to monitor the inlet flow in real time. The compensation controller is connected to the inlet flow meter to adjust the speed of the external return pump or the number of units turned on according to the change of the inlet flow. When the inlet flow increases, the compensation controller increases the speed of the external return pump or turns on more units in advance; when the inlet flow decreases, the compensation controller reduces the speed of the external return pump or shuts down some pumps accordingly to prevent excessive dilution of the sludge concentration in the reaction tank. For example, when the inlet flow increases by 20%, the compensation controller will immediately increase the speed of the external return pump by 10%; when the inlet flow decreases by 10%, the compensation controller will immediately reduce the speed of the external return pump by 5%.

[0037] The implementation principle of this embodiment is: by real-time monitoring of water quality parameters and microbial concentrations, combined with advanced automatic control technology and mathematical models, accurate control of the internal and external return systems is achieved. This system not only improves the efficiency and stability of sewage treatment, but also greatly reduces operating costs and improves environmental quality. It is particularly worth mentioning that the application of flow feedforward control and dynamic compensation mechanism enables the system to quickly respond to changes in water quality and flow, ensuring the continuous stability of the treatment effect.

[0038] Embodiment 2: Reference Figure 2 The difference between this embodiment and the above embodiment is that nitrogen balance feedback control of the internal reflow system and sludge balance feedback control of the external reflow system are added.

[0039] The nitrogen balance feedback control of the internal reflow system includes a nitrate nitrogen generation calculation module, a denitrification removal calculation module and an adjustment module. The nitrate nitrogen generation calculation module calculates the actual nitrate nitrogen generation based on the inlet ammonia nitrogen concentration (IN_NH3-N), the effluent ammonia nitrogen concentration (OUT_NH3-N), the nitrate nitrogen concentration at the end of the aerobic pool (NO3⁻-N_O) and the nitrate nitrogen concentration at the inlet of the anoxic pool (NO3⁻-N_A). The specific method is: use the formula R = (NO3⁻-N_O - NO3⁻-N_A) / NO3⁻-N_A *100%, where R is the internal reflow ratio.

[0040] The denitrification removal calculation module calculates the amount of nitrate nitrogen removed by denitrification based on the above concentration parameters. The specific method is: use the formula QR = QIN * R, where QR is the internal reflow flow rate and QIN is the influent flow rate. These two modules work together to ensure the balance of nitrification and denitrification reactions.

[0041] The adjustment module adjusts the internal reflux ratio according to the deviation of the actual nitrate nitrogen concentration from the target range. The specific method is: when the actual nitrate nitrogen concentration deviates from the target range, the adjustment module adjusts the internal reflux ratio according to the deviation to restore it to the target range. For example, when the actual nitrate nitrogen concentration is 10% higher than the target range, the adjustment module will immediately increase the internal reflux ratio by 5%; when the actual nitrate nitrogen concentration is 10% lower than the target range, the adjustment module will immediately reduce the internal reflux ratio by 5%.

[0042] The sludge balance feedback control of the external recirculation system includes a biological reactor mixed liquor sludge concentration calculation module, a target sludge concentration setting module and an adjustment module. The biological reactor mixed liquor sludge concentration calculation module calculates the sludge growth according to the mixed liquor sludge concentration of the biochemical reactor (MLSSR), the secondary sedimentation tank sludge concentration (MLSSS) and the influent flow (QIN). The specific method is: use the formula RE = (MLSSR - MLSSS) / MLSSS * 100%, where RE is the external recirculation ratio.

[0043] The target sludge concentration setting module is used to set the target sludge concentration range in the biochemical reaction tank. The specific method is: determine the target sludge concentration range according to the treatment process and water quality requirements. For example, the target sludge concentration range can be set to 3000-5000 mg / L according to local environmental protection standards and the actual situation of the factory.

[0044] The adjustment module adjusts the external reflow ratio according to the deviation of the actual sludge concentration from the target range. The specific method is: when the actual sludge concentration deviates from the target range, the adjustment module adjusts the external reflow ratio according to the deviation to restore it to the target range. For example, when the actual sludge concentration is 10% lower than the target range, the adjustment module will immediately increase the external reflow ratio by 5%; when the actual sludge concentration is 10% higher than the target range, the adjustment module will immediately reduce the external reflow ratio by 5%.

[0045] The implementation principle of this embodiment is: by introducing nitrogen balance feedback control and sludge balance feedback control, the refined management level of sewage treatment is further improved. These two feedback control mechanisms can not only monitor and adjust the operating status of the internal and external return systems in real time, but also effectively respond to sudden changes in water quality to ensure the efficient and stable operation of the entire system. Especially for complex and changeable sewage treatment scenarios, this refined control strategy can significantly improve the treatment effect and economic benefits.

[0046] Embodiment 3: The difference between this embodiment and the above-mentioned embodiment lies in that an empirical relationship database and a proportional coefficient dynamic adjustment module are added to the flow feedforward compensation control strategy of the external reflow system.

[0047] The flow feedforward compensation control strategy of the external reflow system includes an inlet flow meter and a compensation controller. The inlet flow meter is installed on the inlet pipe to monitor the inlet flow in real time. The compensation controller is connected to the inlet flow meter to adjust the speed of the external reflow pump or the number of pumps turned on according to the change of the inlet flow. When the inlet flow increases, the compensation controller increases the speed of the external reflow pump in advance or turns on more pumps; when the inlet flow decreases, the compensation controller reduces the speed of the external reflow pump or shuts down some pumps accordingly to prevent excessive dilution of the sludge concentration in the reaction tank.

[0048] In addition, the strategy also includes an empirical relationship database and a proportional coefficient dynamic adjustment module. The empirical relationship database stores the empirical relationship between the inlet flow rate and the external return flow rate under different working conditions. For example, it can be concluded through historical data analysis that when the inlet flow rate increases by 1 m³ / min, the external return flow rate needs to increase by 0.5 m³ / min to maintain the best treatment effect. These empirical relationships can be stored in the database for subsequent use.

[0049] The proportional coefficient dynamic adjustment module dynamically adjusts the proportional coefficient K according to the real-time monitored inlet flow and the empirical relationship. The specific method is: when the inlet flow changes, the proportional coefficient dynamic adjustment module adjusts the value of K according to experience and current working conditions, and then uses the formula QRE = K * QIN to calculate the external return flow. For example, when the inlet flow increases from 10 m³ / min to 12 m³ / min, the proportional coefficient dynamic adjustment module will adjust the value of K according to the empirical relationship library. Assuming that K is adjusted from 0.5 to 0.6, the new external return flow is QRE = 0.6 * 12 = 7.2 m³ / min.

[0050] The implementation principle of this embodiment is: by introducing the empirical relationship database and the proportional coefficient dynamic adjustment module, the flexibility and adaptability of the external return system are further enhanced. This dynamic adjustment mechanism can adaptively adjust the external return flow under different working conditions to ensure that the system is always in the optimal operating state. This is very useful for dealing with seasonal changes, emergencies, etc., and can significantly improve the reliability and economy of sewage treatment.

[0051] Embodiment 4: The difference between this embodiment and the above-mentioned embodiment lies in that various types of sensors and technical means are used to improve the robustness and accuracy of the system.

[0052] The online water quality monitoring equipment in the internal recirculation system can not only use traditional electrochemical sensors and optical sensors, but also introduce new wireless sensor network technology. For example, a nitrate nitrogen sensor with Bluetooth communication function is installed at the outlet of the aerobic pool, and an ammonia nitrogen sensor with multi-channel data acquisition function is installed at the entrance of the anoxic pool. These sensors can transmit data to the central controller through a wireless network, reducing the complexity of wiring and the difficulty of maintenance.

[0053] In the external recirculation system, in addition to conventional suspended solids measuring instruments, laser scattering and fluorescent labeling technology can also be introduced. Laser scattering can provide higher resolution particle size distribution data, which helps to more accurately determine MLSS and MLVSS. Fluorescent labeling technology can be used to track the migration path of specific components and evaluate the activity and health status of sludge.

[0054] The implementation principle of this embodiment is: by introducing various types of new technologies and sensors, the robustness and accuracy of the system are greatly improved. These new technologies can not only provide data support in more dimensions, but also simplify the maintenance and management of the system. Especially in complex sewage treatment environments, this comprehensive technical means can significantly improve the overall performance and reliability of the system.

[0055] Embodiment 5: The difference between this embodiment and the above-mentioned embodiment is that the fault diagnosis and early warning functions of the system are strengthened to improve the safety of the system.

[0056] Both the internal and external reflow systems are equipped with fault diagnosis modules. The fault diagnosis module is responsible for real-time monitoring of the operating status of each component, such as whether the sensor is working properly, whether the pump has abnormal vibration, whether the circuit is short-circuited, etc. Once a potential fault point is detected, the fault diagnosis module will immediately issue a warning signal and record the relevant fault log.

[0057] In addition, the system also has an intelligent early warning function. The intelligent early warning module predicts possible failure trends by analyzing historical data and real-time data. For example, when the nitrate nitrogen concentration shows an upward trend for several consecutive days, the intelligent early warning module will remind the operator to check the aeration system of the aerobic tank to prevent serious nitrification deficiency. Similarly, when the sludge concentration suddenly drops, the intelligent early warning module will prompt the operator to check for possible leaks or emptying problems.

[0058] To further improve the safety of the system, all sensors and controllers are designed with redundancy. Each key node has a backup device. When the main device fails, the backup device can immediately take over the task to ensure the uninterrupted operation of the system. For example, two independent nitrate nitrogen sensors and ammonia nitrogen sensors are installed at each important location, one for the main function and the other for the backup function. When the main sensor fails, the backup sensor will automatically switch to ensure the normal operation of the system through seamless connection.

[0059] The implementation principle of this embodiment is: by integrating fault diagnosis and intelligent early warning functions, the safety and reliability of the system are greatly improved. These advanced functions can not only detect and handle potential faults in a timely manner, but also prevent major accidents and ensure the stable operation of the sewage treatment system. Especially in large sewage treatment plants, this comprehensive safety measure is particularly important and can significantly improve the overall operation and maintenance level and user experience.

[0060] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An automatic control system for internal and external reflux of sewage treatment, characterized in that: include: The internal recirculation system is used to control the working status of the internal recirculation pump according to the feedback of water quality parameters. Specifically, by monitoring the changes of water quality parameters such as nitrate nitrogen (NO3⁻-N), nitrite nitrogen (NO2⁻-N), ammonia nitrogen (NH3-N) and dissolved oxygen (DO), the frequency or number of internal recirculation pumps opened is adjusted to maintain the balance of nitrification and denitrification reactions; The external reflow system is used to control the working status of the external reflow pump according to the feedback of the microbial concentration and activity and the operating status of the secondary sedimentation tank. Specifically, by monitoring the sludge concentration (MLSS) or volatile sludge concentration (MLVSS) and the mud level, the flow rate of the external reflow pump is adjusted to maintain the microbial concentration and activity in the biological reaction tank.

2. The automatic control system for internal and external reflux of sewage treatment according to claim 1 is characterized in that: The internal reflux system comprises: Online water quality monitoring equipment, installed at key locations, is used to monitor water quality parameters such as ammonia nitrogen and nitrate nitrogen in real time; The controller is connected to the online water quality monitoring equipment and is used to adjust the speed or number of internal reflux pumps according to the preset water quality target value. When the concentration of ammonia nitrogen or nitrate nitrogen is detected to deviate from the target range, the controller automatically adjusts the speed or number of internal reflux pumps to restore the water quality to the set range as soon as possible.

3. The automatic control system for internal and external reflux of sewage treatment according to claim 2 is characterized in that: The controller further comprises: The mathematical model module is used to establish a mathematical model between water quality parameters and internal reflow flow, and to correct the model parameters through feedback from historical data and real-time monitoring data. The historical data and real-time monitoring data are used to continuously optimize the model parameters and improve the accuracy and timeliness of control.

4. The automatic control system for internal and external reflux of sewage treatment according to claim 3 is characterized in that: The flow feedforward control strategy of the internal reflux system includes: Flow meter, installed on the water inlet pipe, used to monitor the water inlet flow in real time; The feedforward controller is connected to the flow meter and is used to predict and adjust the output flow of the internal reflux pump in advance according to the change of the inlet flow. When the inlet flow increases, the feedforward controller increases the output flow of the internal reflux pump in advance; when the inlet flow decreases, the feedforward controller reduces the output flow of the internal reflux pump accordingly to ensure the denitrification effect of the system.

5. The automatic control system for internal and external reflux of sewage treatment according to claim 1 is characterized in that: The external reflux system comprises: Microbial concentration monitoring equipment, installed in the biochemical reaction tank and the secondary sedimentation tank, is used to monitor the sludge concentration (MLSS) or volatile sludge concentration (MLVSS) in real time; The controller is connected to the microbial concentration monitoring equipment and is used to adjust the flow of the external return pump according to the preset target sludge concentration range. When the MLSS or MLVSS is lower than the preset lower limit, the controller automatically increases the flow of the external return pump; when the MLSS or MLVSS is higher than the preset upper limit, the controller automatically reduces the flow of the external return pump to maintain the microbial concentration within an appropriate range.

6. The automatic control system for internal and external reflux of sewage treatment according to claim 5 is characterized in that: The controller further comprises: The mud level monitoring device is installed in the secondary sedimentation tank to monitor the mud level height of the secondary sedimentation tank; The dynamic compensation module is used to dynamically adjust the external reflow ratio according to the mud level and other operating parameters. When the mud level is too high, the dynamic compensation module increases the external reflow ratio to lower the mud level; when the mud level is too low, the dynamic compensation module reduces the external reflow ratio to save energy and maintain stable operation of the system.

7. The automatic control system for internal and external reflux of sewage treatment according to claim 6 is characterized in that: The flow feedforward compensation control strategy of the external reflux system includes: The water inlet flow meter is installed on the water inlet pipe to monitor the water inlet flow in real time; The compensation controller is connected to the water inlet flow meter and is used to adjust the speed of the external return pump or the number of pumps turned on according to the change of the water inlet flow. When the water inlet flow increases, the compensation controller increases the speed of the external return pump in advance or turns on more pumps; when the water inlet flow decreases, the compensation controller reduces the speed of the external return pump or shuts down some pumps accordingly to prevent excessive dilution of the sludge concentration in the reaction tank.

8. The automatic control system for internal and external reflux of sewage treatment according to claim 7 is characterized in that: The nitrogen balance feedback control of the internal reflux system includes: The nitrate nitrogen generation calculation module is used to calculate the actual nitrate nitrogen generation based on the inlet ammonia nitrogen concentration (IN_NH3-N), the effluent ammonia nitrogen concentration (OUT_NH3-N), the nitrate nitrogen concentration at the end of the aerobic pool (NO3⁻-N_O) and the nitrate nitrogen concentration at the inlet of the anoxic pool (NO3⁻-N_A). The formula is used R=(NO3⁻-N_O-NO3⁻-N_A) / NO3⁻-N_A*100%, where R is the internal reflux ratio; The denitrification removal calculation module is used to calculate the amount of nitrate nitrogen removed by denitrification based on the above concentration parameters, using the formula QR=QIN*R, where QR is the internal reflux flow and QIN is the water inlet flow; The adjustment module is used to adjust the internal reflux ratio according to the deviation of the actual nitrate nitrogen concentration from the target range. When the actual nitrate nitrogen concentration deviates from the target range, the adjustment module adjusts the internal reflux ratio according to the deviation to restore it to the target range.

9. The automatic control system for internal and external reflux of sewage treatment according to claim 8, characterized in that: The sludge balance feedback control of the external reflow system includes: The biological reactor mixed liquor sludge concentration calculation module is used to calculate the sludge growth according to the mixed liquor sludge concentration of the biochemical reactor (MLSSR), the sludge concentration of the secondary sedimentation tank (MLSSS) and the influent flow (QIN), using the formula RE=(MLSSR-MLSSS) / MLSSS*100%, where RE is the external reflow ratio; The target sludge concentration setting module is used to set the target sludge concentration range in the biochemical reaction tank, and the target sludge concentration range is determined according to the treatment process and water quality requirements; The adjustment module is used to adjust the external reflow ratio according to the deviation of the actual sludge concentration from the target range. When the actual sludge concentration deviates from the target range, the adjustment module adjusts the external reflow ratio according to the deviation to restore it to the target range.

10. The automatic control system for internal and external reflux of sewage treatment according to claim 9, characterized in that: The flow feedforward compensation control of the external reflux system also includes: An empirical relationship database stores the empirical relationship between the inlet flow rate and the external return flow rate under different working conditions; The proportional coefficient dynamic adjustment module is used to dynamically adjust the proportional coefficient K according to the real-time monitored water flow and empirical relationship. When the water flow changes, the proportional coefficient dynamic adjustment module adjusts the value of K according to experience and current working conditions, and then uses the formula QRE=K*QIN Calculate the external return flow rate.

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