MSBR limit denitrification method based on multi-stage and multi-section dissolved oxygen intelligent regulation and control

Abstract

The invention relates to the technical field of sewage treatment, in particular to an MSBR limit denitrification method based on multi-stage and multi-section dissolved oxygen intelligent regulation and control, which comprises the following steps: arranging physical partitions in a main aeration aerobic unit of an MSBR along a water flow direction, constructing a plurality of independent aeration areas, and forming a'high-medium-low 'dissolved oxygen concentration space gradient field through partition regulation and control; in combination with real-time monitoring data, constructing a dissolved oxygen trend prediction model, and dynamically optimizing a dissolved oxygen concentration gradient field form and a carbon source multi-point differential adding strategy according to a water inlet C / N ratio; and meanwhile, a graded impact judgment and quick response mechanism is established. Through cooperation of a physical configuration and an intelligent algorithm, coupling of multiple denitrification paths is achieved, the denitrification limit of a traditional activated sludge method is broken through, the total nitrogen in effluent of the MSBR is as low as 1.5 mg / L, the daily mean value is smaller than 4 mg / L, energy consumption and chemical consumption are remarkably reduced, the impact resistance of the system is enhanced, and an innovative solution is provided for deep denitrification of sewage.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an MSBR extreme denitrification method based on multi-stage and multi-segment intelligent control of dissolved oxygen. Background Technology

[0002] Nitrogen is a major cause of eutrophication in water bodies, and improving the nitrogen removal efficiency of wastewater treatment plants is crucial for mitigating eutrophication. Currently, widely researched biological nitrogen removal technologies include: deeply exploring the nitrogen removal potential of existing biological treatment processes, adding denitrifying biological filters for advanced treatment, developing short-cut denitrification coupled with anaerobic ammonia oxidation, and developing aerobic granular sludge processes. Considering the requirements for synergistic efficiency in pollution reduction and carbon reduction, and the maturity of process applications, deeply exploring the nitrogen removal potential of existing biological treatment processes remains the most practical and feasible technical solution. Numerous studies and engineering cases have shown that modified sequencing batch reactors (MSBRs) have advantages such as small footprint, high influent carbon source utilization, and good nitrogen and phosphorus removal effects. They are an advanced biological treatment process suitable for wastewater treatment plants with high discharge standards. Therefore, it is necessary to achieve iterative development of MSBR biological nitrogen removal towards higher efficiency, lower carbon emissions, and greater intelligence through refined design and intelligent control.

[0003] Currently, MSBR processes are mainly managed on-site based on the experience of technical personnel. For example, the overall dissolved oxygen (DO) concentration in the main aerobic unit is controlled according to traditional experience at 2-4 mg / L. This not only brings a large amount of dissolved oxygen to the sludge mixed liquor returned to the anoxic unit, affecting the anoxic environment of the anoxic unit and consuming some of the influent organic carbon source, but also increases the aeration energy consumption of the blower and the amount of external carbon source added. Furthermore, it is not conducive to the formation of the macro-environment and micro-environment for short-cut nitrification, simultaneous nitrification and denitrification in the main aerobic unit (an anoxic state exists inside the flocs). Therefore, the existing manual experience-based control mode of MSBR has drawbacks such as high energy consumption, high chemical consumption, inability to actively guide the synergistic coupling of multiple denitrification pathways, and lack of intelligent control, making it difficult to achieve the ultimate denitrification effect. Summary of the Invention

[0004] To address these issues, this invention provides a method for extreme nitrogen removal in MSBR based on multi-stage and multi-segment intelligent control of dissolved oxygen. This method overcomes the problems in existing technologies, such as the disconnect between the model and the MSBR process structure, the reliance on complex parameters leading to high implementation costs, the inability to actively guide the synergistic effect of multiple nitrogen removal pathways, and the lack of a foundation for achieving deep energy savings through physical structure.

[0005] To achieve the above objectives, this invention provides a MSBR extreme nitrogen removal method based on multi-stage, multi-segment intelligent control of dissolved oxygen, comprising:

[0006] Step S1: The main aerobic aeration unit of the MSBR reactor is physically separated along the water flow direction and divided into multiple independent aeration zones. Each aeration zone is equipped with an independent aeration pipeline and control valve.

[0007] Step S2: Based on the influent water quality characteristics of the MSBR tank, each aeration unit is independently aerated to actively form and maintain a spatial gradient field of dissolved oxygen concentration that changes continuously from "high-medium-low" along the water flow direction in the main aerobic aeration unit, thereby creating a multi-segment dissolved oxygen environment in the main aerobic aeration unit.

[0008] Step S3: Real-time monitoring of water quality parameters, water volume, water temperature, dissolved oxygen concentration, sludge concentration and microbial community characteristics in each zone of the main aeration aerobic unit in the influent and the MSBR reactor to form a multi-source monitoring dataset;

[0009] Step S4: Based on the acquired multi-source monitoring dataset, use intelligent control algorithms to dynamically adjust aeration intensity, sludge return ratio, sludge concentration, sludge discharge strategy and carbon source addition strategy to coordinate and regulate short-cut nitrification-denitrification, full-process nitrification-denitrification and simultaneous nitrification-denitrification denitrification pathways.

[0010] Step S5 involves passing the wastewater through the inherent multi-stage reaction environment of the MSBR tank, and achieving deep denitrification through the synergistic effect of the multi-segment dissolved oxygen gradient environment and intelligent control algorithm within the main aeration aerobic unit.

[0011] Furthermore, in step S1, the physical partition is a flow guide wall with regularly spaced water passages, used to guide the water flow sequentially through each zone aeration unit to suppress the mixing of successive water flows.

[0012] Further, step S4 includes:

[0013] Step S41: Sequentially obtain the dissolved oxygen concentration of each zone along the influent flow direction, determine and dynamically adjust the aeration intensity of each zone to stabilize the dissolved oxygen spatial gradient.

[0014] Step S42: Based on historical and real-time data, construct a dissolved oxygen trend prediction model, and based on the instantaneous change rate of influent flow and pollutant concentration monitored in real time, make a short-term shock risk assessment.

[0015] Step S43: Based on the real-time influent carbon-nitrogen ratio and pollutant load, the morphological parameters of the "high-medium-low" gradient field are optimized in a coordinated manner. At the same time, based on the carbon source requirements of the dominant denitrification pathway and the real-time feedback of the effluent nitrate nitrogen concentration, a carbon source on-demand, intermittent addition strategy is generated and executed in the first anoxic unit and / or the second anoxic unit, and the short-cut nitrification-denitrification, full-process nitrification-denitrification and simultaneous nitrification-denitrification denitrification pathways are coordinated and controlled.

[0016] Step S44: Based on the real-time feedback of water temperature changes, total nitrogen concentration in the effluent, and microbial community characteristics, adjust the sludge return ratio, system sludge concentration, and sludge discharge strategy in a coordinated manner.

[0017] Further, in step S42, the short-term shock risk assessment includes:

[0018] If the instantaneous change rate of the influent flow rate or the concentration of key pollutants exceeds the first preset threshold, it is determined to be a mild shock, and the aeration intensity of each zone aeration unit is immediately increased according to the preset ratio.

[0019] If the instantaneous change rate of the influent flow rate or the concentration of key pollutants exceeds the second preset threshold, it is determined to be a severe shock. At the same time, while increasing the aeration intensity, the control algorithm is switched to a higher frequency sampling and adjustment cycle.

[0020] Further, in step S42, the dissolved oxygen trend prediction model is constructed based on the theoretical oxygen consumption and the adaptive correction factor, wherein,

[0021] The theoretical oxygen demand is determined based on carbon oxidation oxygen demand, nitrification oxygen demand, denitrification recovered oxygen equivalent, and a comprehensive correction factor for hydraulic effects.

[0022] The adaptive correction factor is calculated based on the deviation between the predicted total oxygen demand (OTR) of the system and the actual oxygen demand (OTRa) of the system.

[0023] Further, step S43 includes:

[0024] When the influent chemical oxygen demand is below the third threshold, the spatial proportion of the "high" oxygen zone is narrowed, and the spatial proportion of the "low" oxygen zone and "medium" oxygen zone is significantly expanded, so as to form a wide range of anoxic / aerobic alternating microenvironment in the aerobic unit, enhance simultaneous nitrification and denitrification, and provide an advantageous environment for short-cut nitrification and denitrification.

[0025] When the influent chemical oxygen demand is between the third and fourth thresholds, the spatial proportions of the "high", "medium" and "low" zones are maintained with significant differences and balance, so as to achieve the parallel and complementary functions of short-cut nitrification and denitrification, full-process nitrification and denitrification and simultaneous nitrification and denitrification in space, and to achieve efficient coupling of multiple denitrification mechanisms through gradient field morphology optimization.

[0026] When the influent chemical oxygen demand exceeds the fourth threshold, the proportion of the high-oxygen zone is increased while the proportion of the low-oxygen zone is reduced to ensure complete nitrification capacity under high organic load, while creating strict denitrification conditions for subsequent anoxic units, thus ensuring the efficient operation of the entire nitrification-denitrification pathway.

[0027] Further, step S44 includes:

[0028] Step S441, water temperature adaptive control: When the water temperature is detected to be continuously below the fifth threshold, the winter operation mode is activated to increase the sludge concentration in the system and increase the total amount of carbon source added as needed;

[0029] Step S442, effluent feedback closed-loop control: Based on the real-time measurement value of the total nitrogen concentration in the effluent, the overall dissolved oxygen level of the main aeration aerobic unit and the total amount of external carbon source added are adjusted in a closed loop.

[0030] Step S443, Sludge Age Optimization and Control: Based on the analysis results of microbial community characteristics, dynamically adjust the sludge discharge volume to optimize the sludge age of the system and maintain the dominant position of functional microorganisms.

[0031] Furthermore, the winter operation mode also includes adjusting the dissolved oxygen control range of each zone in the main aeration aerobic unit.

[0032] Furthermore, the comprehensive correction factor for hydraulic influence is determined based on the product of the flow load impact factor and the velocity / mixing efficiency factor, wherein,

[0033] The flow load impact factor is determined based on the deviation between the current flow rate and the recent average flow rate;

[0034] The flow rate / mixing efficiency factor is determined based on the actual flow rate or actual hydraulic residence time within the main aeration unit.

[0035] On the other hand, the present invention also provides a wastewater treatment system employing the aforementioned extreme nitrogen removal method based on multi-stage and multi-segment intelligent dissolved oxygen regulation, comprising:

[0036] The main aerobic aeration unit is a rectangular tank with physical partitions along its length, dividing it into multiple independent aeration zones. Each aeration zone is equipped with its own aeration pipeline and control valves.

[0037] A carbon source multi-point dosing unit includes at least one first dosing device disposed in a first anoxic unit or a second anoxic unit, and a second dosing device disposed downstream of the effluent of the main aeration aerobic unit in a first anoxic / aerobic unit or a second anoxic / aerobic unit.

[0038] The multi-parameter online monitoring unit includes an online analyzer for monitoring influent water quality, dissolved oxygen sensors and sludge concentration meters installed in each zone of the main aeration aerobic unit;

[0039] The intelligent control unit is communicatively connected to the multi-parameter online monitoring unit, the various air volume regulating valves of the partitioned main aeration aerobic unit, the carbon source multi-point dosing unit, and the sludge return and discharge device, in order to execute the above-mentioned extreme denitrification method based on multi-stage and multi-segment intelligent control of dissolved oxygen.

[0040] Compared with existing technologies, the beneficial effects of this invention are that it achieves extreme denitrification and high energy efficiency in MSBR processes under low C / N ratio conditions by constructing a main aeration unit partitioning and a multi-level dissolved oxygen gradient intelligent control system. Based on the physical construction and dynamic maintenance mechanism of the dissolved oxygen spatial gradient field, combined with a multi-path denitrification synergistic control model and a graded anti-shock control strategy, it fundamentally solves the technical bottlenecks of insufficient denitrification efficiency, serious carbon source waste, weak shock resistance, and high energy consumption in traditional processes. Through the stable biochemical environment formed by physical isolation and the refined synergy of intelligent algorithms, a composite advantage of "stable structure and superior algorithm performance" is formed, significantly improving the adaptability, economy, and reliability of the system under high-standard effluent requirements, providing an innovative technical solution for energy saving, consumption reduction, and upgrading of wastewater treatment.

[0041] Furthermore, this invention provides a physical basis for the stable existence of the dissolved oxygen gradient by setting physical partitions within the rectangular main aeration unit to form series zones. By independently controlling the aeration intensity of each zone, a "high-medium-low" dissolved oxygen spatial gradient field can be actively constructed and precisely maintained, enabling different denitrification pathways such as short-cut nitrification / denitrification, full-process nitrification / denitrification, and simultaneous nitrification / denitrification to obtain the optimal reaction environment in space.

[0042] Furthermore, this invention integrates a dissolved oxygen trend prediction model with an instantaneous shock judgment mechanism to form a graded and forward-looking shock-resistant control system. Trend prediction based on historical and real-time data enables proactive adaptation to medium- and long-term changes in influent load, while rapid judgment based on instantaneous change rate ensures timely response to sudden shocks. This allows the system to adjust operating parameters in advance to ensure stability when facing fluctuations in water quality and quantity, while avoiding energy waste caused by overreaction, significantly enhancing the robustness and economy of the process.

[0043] Furthermore, this invention establishes a dynamic decision-making and optimization mechanism for denitrification pathways based on the influent carbon-to-nitrogen ratio, enabling adaptive switching of operating modes. The system can automatically select and enhance the most suitable and advantageous denitrification pathways according to the influent water quality characteristics, and accordingly adjust dissolved oxygen gradient parameters and carbon source addition strategies. This ensures that the process prioritizes short-cut nitrification and denitrification to conserve carbon sources under low-carbon conditions, while ensuring complete nitrification and denitrification when carbon sources are sufficient, significantly improving treatment efficiency and resource utilization.

[0044] Furthermore, this invention forms a complete technical closed loop by integrating structured control, intelligent path optimization, and systematic anti-disturbance regulation. While achieving a long-term stable total nitrogen level below 2 mg / L in the effluent, the system's blower energy consumption can be reduced by approximately 40%, and the carbon source dosage by approximately 30%. Moreover, due to the stable high standards of the biological effluent, subsequent advanced treatment units can be simplified or even eliminated. This comprehensive improvement in technical performance, operating costs, and environmental benefits provides a practical solution for high-standard, low-carbon operation of urban wastewater treatment. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the planar structure of the main aeration unit for partitioned dissolved oxygen regulation in the MSBR extreme denitrification method based on multi-stage and multi-segment intelligent dissolved oxygen control according to the present invention.

[0046] Figure 2 This is a flowchart of the MSBR extreme denitrification method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to the present invention;

[0047] Figure 3 This is a flowchart of step S4 of the MSBR extreme denitrification method based on multi-stage and multi-segment intelligent control of dissolved oxygen in this invention;

[0048] Figure 4 This is a flowchart of step S44 of the MSBR extreme denitrification method based on multi-stage and multi-segment intelligent control of dissolved oxygen in this invention;

[0049] Figure 5 These are high-throughput sequencing results of the activated sludge microbial community.

[0050] Figure 6 Annotation results for the nitrogen cycle database of activated sludge metagenomic sequencing.

[0051] In the diagram: 1. Flow guide wall; 2. Water flow direction; 3. Zoned aeration unit. Detailed Implementation

[0052] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0053] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0054] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0055] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0056] Please see Figure 1-2 As shown, Figure 1 This is a schematic diagram of the DO planar structure of the main aeration unit of the MSBR extreme denitrification method based on multi-stage and multi-segment intelligent control of dissolved oxygen, as described in this invention. Figure 2 This invention relates to an MSBR extreme denitrification method based on multi-stage and multi-segment intelligent control of dissolved oxygen.

[0057] This invention relates to an MSBR-based extreme nitrogen removal method based on multi-stage, multi-segment intelligent dissolved oxygen regulation, applied to wastewater treatment. Specifically, it can be implemented as a wastewater treatment system, including:

[0058] The main aerobic aeration unit is a rectangular tank with physical partitions along its length, dividing it into multiple independent aeration zones. Each aeration zone is equipped with its own aeration pipeline and control valves.

[0059] The carbon source multi-point dosing unit includes at least one first dosing device located at the inlet or anaerobic unit, and a second dosing device located at the front end of the sequencing unit downstream of the effluent of the main aeration aerobic unit.

[0060] The multi-parameter online monitoring unit includes an online analyzer for monitoring influent water quality, a dissolved oxygen sensor, a sludge concentration meter, a flow meter, and a thermometer installed in each zone of the main aeration aerobic unit;

[0061] The intelligent control unit is communicatively connected to the multi-parameter online monitoring unit, the various air volume regulating valves of the partitioned main aerobic aeration unit, the carbon source multi-point dosing unit, and the sludge return and discharge device, in order to execute the extreme denitrification method based on multi-stage and multi-segment intelligent control of dissolved oxygen.

[0062] Specifically, an embodiment of the present invention provides an MSBR extreme nitrogen removal method based on multi-stage, multi-segment intelligent control of dissolved oxygen, comprising:

[0063] Step S1: The main aerobic aeration unit of the MSBR reactor is physically separated along the water flow direction and divided into multiple independent aeration zones. Each aeration zone is equipped with an independent aeration pipeline and control valve.

[0064] It is understandable that the MSBR tank includes anaerobic, anoxic, main aerobic, and sequencing batch reactor units. The above-mentioned partitioned structure modification is a core innovation without changing the main MSBR process flow, aiming to create a gradient dissolved oxygen environment within the main aerobic unit.

[0065] Specifically, within the existing rectangular main aerobic aeration unit, two parallel flow-guiding partitions are added along its length. These partitions physically divide the main aerobic aeration unit into three independent aeration zones connected in series: a front zone, a middle zone, and a rear zone. The partitions effectively guide the water flow to cover the entire area, suppressing mixing between the initial and subsequent water flows. The original uniformly distributed aeration pipe network is transformed into three independent aeration branch loops, each serving one of the three zones. Each branch is equipped with a regulating valve and a flow meter, and connected to a variable frequency blower to achieve independent and precise control of the aeration volume in each zone. Dissolved oxygen (DO) online sensors are installed in each zone; sludge concentration (MLSS) online monitors and total nitrogen (TN) online analyzers are installed at the end of the aerobic unit and the system's main outlet, respectively; and sodium acetate precision dosing devices are added at the front end of the first or second anoxic unit, or the first / second anoxic / aerobic unit. By integrating all the aforementioned sensors and actuators, the intelligent control software described in this invention is deployed. This software includes core modules such as a dissolved oxygen trend prediction model, a denitrification path decision logic, and an anti-impact regulation algorithm.

[0066] Step S2: Based on the influent water quality characteristics of the MSBR tank, each aeration unit is independently aerated to actively form and maintain a spatial gradient field of dissolved oxygen concentration that changes continuously from "high-medium-low" along the water flow direction in the main aerobic aeration unit, thereby creating a multi-segment dissolved oxygen environment in the main aerobic aeration unit.

[0067] Specifically, after the system starts up, based on the characteristics of the influent water quality (C / N≈5.7), differentiated dissolved oxygen control targets are set for the three zones: front zone: 2 mg / L; middle zone: 1.8 mg / L; and rear zone: 0.5 mg / L. By independently adjusting the air volume regulating valves of each zone, the system quickly establishes and stably maintains a spatial gradient field of "high-medium-low" dissolved oxygen concentration within the main aeration unit.

[0068] By forming a spatial gradient field of dissolved oxygen concentration, the effective residence time of water flow in the main aerobic aeration unit is increased, allowing water to pass through high-oxygen (front section), medium-oxygen (middle section), and low-oxygen (rear section) environments in sequence to achieve synergistic denitrification through pathways such as short-cut nitrification and denitrification, full-process nitrification and denitrification, and simultaneous nitrification and denitrification.

[0069] Step S3: Real-time monitoring of water quality parameters, water volume, water temperature, dissolved oxygen concentration, sludge concentration and microbial community characteristics in each zone of the main aeration aerobic unit in the influent and the MSBR reactor to form a multi-source monitoring dataset;

[0070] Data such as influent flow rate, COD, NH4⁺-N concentration, DO value of each zone (dissolved oxygen), mixed liquor sludge concentration (MLSS), and total nitrogen value (TN) of effluent are continuously collected and integrated in a 1-minute cycle to form a multi-source real-time monitoring dataset containing time-series characteristics for intelligent decision-making.

[0071] Step S4: Based on the multi-source real-time monitoring dataset, dynamically adjust the aeration intensity, sludge return ratio, sludge concentration, sludge discharge strategy and carbon source addition strategy to coordinate and regulate the short-cut nitrification-denitrification, full-process nitrification-denitrification and simultaneous nitrification-denitrification denitrification pathways.

[0072] Please see Figure 3 The diagram shows a flowchart of step S4 of the MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to the present invention; specifically, step S4 includes:

[0073] Step S41: Sequentially obtain the dissolved oxygen concentration of each zone along the influent flow direction, determine and dynamically adjust the aeration intensity of each zone to ensure the stability of the dissolved oxygen spatial gradient.

[0074] Specifically, based on the dissolved oxygen concentration of each zone in the multi-source monitoring dataset, the real-time deviation between the concentration and the preset target gradient ("high-medium-low") is calculated, and the aeration intensity of the corresponding zone is dynamically adjusted according to the deviation.

[0075] In one specific embodiment, the target DO for the front section is 2 mg / L, for the middle section it is 1.8 mg / L, and for the rear section it is 0.5 mg / L. When the sensor detects that the instantaneous DO value of the front section is lower than 0.8 mg / L, the controller determines to increase the opening of the gas volume regulating valve for that section, so that it recovers to 2 mg / L within 2 to 3 minutes.

[0076] In another specific embodiment, the dissolved oxygen concentration of each zone is obtained sequentially along the influent flow direction, the water flow path-dissolved oxygen concentration curves are constructed for each time series, and the correspondence between the water flow path position and the dissolved oxygen concentration is obtained, so as to dynamically adjust the aeration intensity of each zone.

[0077] Specifically, based on the current water flow velocity, the dissolved oxygen concentration of each zone is obtained sequentially along the inlet flow direction. The average dissolved oxygen concentration of the front zone is set as DO1, the average dissolved oxygen concentration of the middle zone is set as DO2, and the average dissolved oxygen concentration of the rear zone is set as DO3.

[0078] The average flow path length from the previous zone to the target zone is calculated based on the flow velocity of each zone. At this time, the centroid migration path of the fluid segment is used as the motion path. The liquid lag time of the adjacent zone is obtained as the motion path / flow velocity. Based on the change of dissolved oxygen (DO) in the previous zone, the dissolved oxygen (DO) of the target zone is compensated and regulated after the liquid lag time.

[0079] Specifically, for example, if the average dissolved oxygen concentration (DO1) of the front section is greater than the target DO10 of the front section, the dissolved oxygen (DO) of the middle section is regulated based on the rate of change of DO1 detected over time, after a liquid lag time. The regulation amount is the sum of the current gas volume of the section and the gas volume adjustment amount corresponding to the difference between DO10 and DO1. The regulation rate is the same as the rate of change of DO1, but the regulation direction is opposite. That is, if the detected rate of change of DO1 is increasing, the regulation rate is decreasing.

[0080] Step S42: Based on historical and real-time data, construct a dissolved oxygen trend prediction model, and based on the instantaneous change rate of influent flow and pollutant concentration monitored in real time, make a short-term shock risk assessment.

[0081] Specifically, the dissolved oxygen trend prediction model is a dynamic calculation model based on the real-time changes in influent characteristics and hydraulic conditions. The core of the model calculation is the dynamic theoretical oxygen consumption rate, as shown in the following formula:

[0082] OTR=(O C +O N -O D )*f

[0083] Where OTR is the predicted total oxygen demand of the system (kgO2 / h), O COxygen demand for carbon oxidation (kgO2 / h), O N Oxygen demand for nitrification (kgO2 / h) D denoted as the oxygen equivalent recovered by denitrification (kgO2 / h), and f is the comprehensive correction factor for hydraulic impact.

[0084] O C =Q i *(COD i -COD s )*f COD / 1000

[0085] Among them, Q i The influent flow rate (m³ / h) and COD i The influent COD concentration (mg / L), COD s The expected effluent COD concentration (mg / L) set for the system, f COD The oxidation oxygen consumption coefficient (kgO2 / kgCOD) is determined using historical data and typically ranges from 0.4 to 0.6.

[0086] O N =Q i *(NH4 + -N i -NH4 + -N s )*4.57 / 1000

[0087] Among them, NH4 + -N i The influent ammonia nitrogen concentration (mg / L) and NH4+ concentration are given. + -N s The set effluent ammonia nitrogen concentration (mg / L) is given, and 4.57 is the theoretical oxygen consumption coefficient (kgO2 / kgN) for complete nitrification of ammonia nitrogen.

[0088] O D =Q i *(TN i -TN s )*2.86*η DN / 1000

[0089] Among them, TN i The total nitrogen concentration (mg / L) in the influent is TN. s η represents the set total nitrogen concentration in the effluent (mg / L), 2.86 is the oxygen equivalent recovery factor for denitrification (kgO2 / kgN), and η is the oxygen equivalent recovery factor for denitrification. DN The denitrification efficiency correction factor (between 0 and 1) is dynamically adjusted based on real-time feedback from the ORP (oxidation-reduction potential) or nitrate concentration of the anoxic unit.

[0090] The comprehensive hydraulic impact correction factor f is a dynamic correction factor used to quantify the influence of changes in influent flow rate and reactor velocity / mixing state on the actual oxygen consumption process. Its calculation comprehensively considers the following two points:

[0091] Flow load impact factor (f1):

[0092] f1=1+β*(ΔQ / Q avg )

[0093] The deviation between the current flow rate and the recent average flow rate: ΔQ = Q i -Q avg

[0094] In the formula, Q avg The average flow rate over the past 2 hours is given, and β is an empirical coefficient (fitted from historical data, ranging from 0.2 to 0.5).

[0095] When the flow rate increases dramatically, i.e., ΔQ > ΔQA and f1 > 1, it indicates that the rate at which pollutants enter per unit volume accelerates, and the oxygen demand rate of microorganisms is higher; ΔQA is usually set as Q. avg 5% to 10%.

[0096] Conversely, when the flow rate drops sharply, ΔQ < -ΔQA and f1 < 1, indicating that the rate at which pollutants enter per unit volume slows down and the oxygen demand of microorganisms decreases.

[0097] Flow rate / mixing efficiency factor (f2):

[0098] This factor is related to the actual flow velocity or actual hydraulic retention time (HRT) within the main aeration unit. Since the tank structure is fixed, HRT is related to Q. i Inversely proportional: HRT = V / Q i .

[0099] f2=(HRT d / HRT)^γ

[0100] f2=(Q i / Q d )^γ

[0101] Among them, HRT d Q is the preset hydraulic residence time (h). d Preset processing flow rate (m 3 / h), where γ is the exponential coefficient, typically 0.1-0.3, calibrated through tracer experiments or CFD simulations;

[0102] When Q i >Q dWhen the HRT (Heat Reduction Time) is shortened, f2 > 1, indicating more vigorous mixing and faster oxygen mass transfer interface renewal. This results in higher usable dissolved oxygen at the same aeration rate. However, it also requires the aeration system to keep up with the increased mixing rate to prevent localized hypoxia. Therefore, f2 actually affects the assessment of the effective DO (Dissolved Oxygen) supply capacity. Typically, f2 is taken as the value that deviates furthest from 1 among the two values ​​calculated using the above two methods.

[0103] The comprehensive hydraulic influence factor can be expressed as:

[0104] f=f1*f2

[0105] It explicitly states the influent flow rate (Q) i The change in f1 is converted into a correction for the pollutant load shock, and the change in f2 is converted into a correction for the change in mixing and mass transfer conditions in the reactor.

[0106] To compensate for the shortcomings of pure mechanistic models in terms of dynamic response and unknown disturbances, an adaptive correction factor (α) is introduced. t ).

[0107] In one specific embodiment, the adaptive correction factor α t The calculation is performed using a lightweight LSTM network, and its output is determined based on the deviation between the theoretical model output and the actual output. The input X of the lightweight LSTM network is... t This includes the deviation sequence between the recently predicted total oxygen demand (OTR) calculation and the actual aeration rate, the water temperature trend, the deviation sequence of derived characteristics of microbial activity indicators, water temperature, microbial activity, and the recent trend and current value of the comprehensive hydraulic influence factor f.

[0108] In another specific embodiment, the adaptive correction factor α t Based on historical data, the deviation between the predicted total oxygen demand (OTR) and the actual oxygen demand (OTRa) of the system under stable environmental conditions is calculated, i.e., α. t =The mean of OTR / OTRa. When the environment changes, such as when the ambient temperature is adjusted by more than 3°C, the adaptive correction factor α is recalculated. t Understandably, the actual oxygen demand of the system is calculated based on historical data.

[0109] Final Predicted Oxygen Demand (OTR) p =α t *OTR;

[0110] The system is based on the predicted total oxygen demand (OTR). p Combined with the weights of the currently running "high-medium-low" gradient mode, the weights are allocated to each partition and converted into adjusted estimated values ​​of the DO settings.

[0111] Zonal oxygen demand distribution:

[0112] OTR f =w f *OTR p

[0113] OTR m =w m *OTR p

[0114] OTR r =w r *OTR p

[0115] Among them, w f ,w m ,w r Assign weights to the oxygen demand of each partition, and w f +w m +w r =1. The weight is not fixed, but dynamically adjusted according to the denitrification pathway. Preferably, the oxygen demand allocation weight w for the upstream section is... f The oxygen demand allocation weight w for the middle section is set to 0.32. m The oxygen demand allocation weight w for the latter section is set to 0.52. r Set to 0.16.

[0116] DO Adjustment Estimate Calculation:

[0117] ΔDO seti ≈(OTR i / V i ) / KLa i

[0118] Where, ΔDO seti Recommended adjustment amount (mg / L) for dissolved oxygen setpoint of zone i, OTR i For the predicted oxygen demand (kgO2 / h) allocated to partition i, KLa i V is the total oxygen transfer coefficient, a function of aeration intensity and fluid turbulence (i.e., flow velocity / mixing conditions). i The effective volume (m) of partition i 3 A more precise representation could be:

[0119] KLa i =f(Air ratei U i )

[0120] Among them U i The characteristic flow velocity or turbulence intensity (m / s) representing the i-zone, Air rateiThe aeration intensity of zone i (Nm³ air / (h·m)) 3 Pool capacity), can be determined by Q i It can be obtained through deduction or computational fluid dynamics (CFD) models.

[0121] Instantaneous rate of change: for flow rate (Q), COD, NH4 + -N, calculate its first-order forward difference:

[0122] R(t)=[P(t)-P(t-Δt)] / (P(t-Δt)*Δt),

[0123] Where Δt is the sampling interval (e.g., 1 minute), and P represents the parameter value, which can be set to flow rate (Q), COD, NH4+, etc. + Any parameter in -N.

[0124] Comprehensive impact index: I(t) = max(λ*abs(R) Q(t) ),abs(R COD(t) ),abs(R NH4(t) ));

[0125] Where λ is the flow impact weighting factor, usually set to 1.2≤λ≤2.0; abs() is the absolute value function, R Q(t) R is the instantaneous rate of change of influent flow rate at time t. COD(t) R is the instantaneous change rate of influent chemical oxygen demand (COD) at time t. NH4(t) ammonia nitrogen (NH4) at time t + The instantaneous rate of change of N concentration;

[0126] Two impact thresholds are set: the first preset threshold θ1 = 0.1 min. -1 The second preset threshold θ2 = 0.2 min -1 ;

[0127] In this embodiment, the main aerobic aeration unit (Unit 6) of a certain MSBR wastewater treatment plant has completed its zoning modification, and its key design and operating parameters are as follows:

[0128] Total effective volume of unit: V = 10850m³ 3

[0129] Preset processing flow rate: Q d =1667m 3 / h

[0130] Preset hydraulic residence time: HRT d =6.51h

[0131] Zoning setup: Divided into three independent aeration zones along the water flow direction: front, middle, and rear, each zone with a volume V. f=V m =V r ≈3617m 3

[0132] Current operational target: effluent TN ≤ 5 mg / L. Set effluent water quality target value: COD s =30mg / L, NH4 + -N s =1.5mg / L, TN s =5mg / L.

[0133] Key empirical coefficients (calibrated using historical data):

[0134] COD oxidation oxygen consumption coefficient: f COD =0.5kgO2 / kgCOD

[0135] Empirical coefficient for flow impact: β = 0.3

[0136] Mixing efficiency index: γ = 0.15

[0137] Impact judgment threshold: Warning threshold θ1 = 0.2 min -1 θ2=0.4min -1 Traffic weighting factor λ = 1.5.

[0138] In one specific embodiment, on a weekday afternoon, the ambient temperature was 20°C, and the system was operating stably. The measured flow rate Q was: i =1800m 3 / h, Chemical Oxygen Demand (COD) i =220 mg / L, ammonia (NH4) + -N i =28 mg / L, total nitrogen TN i =35mg / L. Average flow rate Q over the past 2 hours avg =1700m 3 / h. The denitrification efficiency η is calculated based on feedback from the anoxic zone sensor. DN =0.85. The lightweight LSTM network outputs the current adaptive correction factor α based on recent operational status. t =1.05.

[0139] Oxygen Demand for Carbon Oxidation C :

[0140] O C =1800*(220-30)*0.5 / 1000=171.0kgO2 / h

[0141] Nitrification Oxygen Demand (NOD):

[0142] ON =1800*(28-1.5)*4.57 / 1000≈218.0kgO2 / h

[0143] Denitrification recovers oxygen equivalent O D :

[0144] O D =1800*(35-5)*2.86*0.85 / 1000≈131.5kgO2 / h

[0145] Calculate the hydraulic influence factor f:

[0146] Flow deviation ΔQ = 1800 - 1700 = 100m 3 / h

[0147] The flow impact factor f1 = 1 + 0.3 * (100 / 1700) ≈ 1.0176

[0148] Actual hydraulic retention time HRT = 10850 / 1800 ≈ 6.028h

[0149] The mixing efficiency factor f2 = (6.51 / 6.028)^0.15 ≈ 1.0116

[0150] The comprehensive hydraulic influence factor f = 1.0176 * 1.0116 ≈ 1.0294

[0151] OTR=(171.0+218.0-131.5)*1.0294≈265.1kgO2 / h

[0152] Calculate the final predicted oxygen demand:

[0153] OTR p =1.05*265.1≈278.4kgO2 / h

[0154] Mapping to the DO settings of each partition to adjust the estimated value:

[0155] The current system operates on a combined short-range and full-range nitrification-denitrification pathway, with the oxygen demand allocation weights for each zone set as follows: w in the front zone f =0.25, middle zone w m =0.45, back zone w r =0.30.

[0156] OTR f =0.25*278.4≈69.6kgO2 / h

[0157] OTR m =0.45*278.4≈125.3kgO2 / h

[0158] OTRr =0.30*278.4≈83.5kgO2 / h

[0159] Based on the total oxygen transfer coefficient (KLa) under the current operating conditions of each zone f =8.0h -1 KLa m =10.0h -1 KLa r =6.0h -1 Estimate DO adjustment amount:

[0160] ΔDO setf ≈(69.6 / 3617) / 8.0≈0.00241kgO2 / m 3 ≈2.41 mg / L

[0161] ΔDO setm ≈(125.3 / 3617) / 10.0≈0.00346kgO2 / m 3 ≈3.46mg / L

[0162] ΔDO setr ≈(83.5 / 3617) / 6.0≈0.00385kgO2 / m 3 ≈3.85mg / L

[0163] Based on model predictions, to cope with current and future short-term inflow loads, it is recommended to adjust the DO settings for each zone from their current levels. Upon receiving this prediction, the controller, guided by theoretical values ​​and considering the stability of real-time DO feedback, will gradually and tentatively increase the DO settings for each zone over the next 30-45 minutes: In the next 30 minutes, the DO setting for the front zone will be gradually increased from the current 1.0 mg / L to 1.5 mg / L, the middle zone from 1.8 mg / L to 2.5 mg / L, and the rear zone from 0.5 mg / L to 1.0 mg / L. This proactive increase aims to enhance the metabolic capacity of the microbial community before it experiences load stress.

[0164] Ten minutes after the model adjustment command was executed, the influent monitoring system detected a sudden data change. The data at time t is compared with the data from one minute prior (time t-1) as follows:

[0165] flow:

[0166] Q(t) = 1900m 3 / h, Q(t-1)=1800m 3 / h

[0167] COD:

[0168] COD(t)=250mg / L, COD(t-1)=220mg / L

[0169] Calculate the instantaneous rate of change:

[0170] R Q =(1900-1800) / (1800*1)=0.0556min -1

[0171] R COD =(250-220) / (220*1)=0.1364min -1

[0172] Calculate the comprehensive impact index:

[0173] I=max(1.5*abs(0.0556),abs(0.1364))=max(0.0834,0.1364)=0.1364min -1

[0174] If I=0.1364)≥θ1=0.10 and<θ2=0.25, the system immediately interrupts the original gradual adjustment process and, based on the existing aeration rate, instructs all zones to synchronously and instantaneously increase the aeration intensity by 10%. If the current total aeration rate is 5000 Nm³, ... 3 / h, then immediately increases to 5500Nm 3 / h. Temporarily switch the control loop cycle from 60 seconds to 30 seconds to achieve faster monitoring and adjustment.

[0175] This shock lasted approximately 15 minutes. The system continuously monitored I values ​​for five cycles (2.5 minutes) that were all below the recovery threshold θ1 = 0.10 min. -1 Afterwards, the impact was determined to have ended. The system then reduced the aeration intensity from 5500 Nm³ / h in an exponential decay manner over 20 minutes. 3 The system smoothly recovers to near the optimized trajectory set by the trend prediction model and adjusts the control cycle back to 60 seconds.

[0176] Step S43: Based on the real-time influent carbon-nitrogen ratio and pollutant load, the morphological parameters of the "high-medium-low" gradient field are optimized in a coordinated manner. At the same time, based on the carbon source requirements of the dominant denitrification pathway and the real-time feedback of the effluent nitrate nitrogen concentration, a carbon source on-demand, intermittent addition strategy is generated and executed in the first anoxic unit and / or the second anoxic unit, and the short-cut nitrification-denitrification, full-process nitrification-denitrification and simultaneous nitrification-denitrification denitrification pathways are coordinated and controlled.

[0177] After model prediction and shock buffering in step S42, the system enters the steady-state optimization stage. At this time, the influent water quality tends to stabilize, and the intelligent control system performs dynamic decision-making on the denitrification path and precise carbon source addition optimization based on the latest monitoring data.

[0178] Known real-time data:

[0179] Influent Chemical Oxygen Demand (COD) i : 245 mg / L (stable monitoring value)

[0180] Influent ammonia nitrogen (NH4) + + -N i ): 26mg / L

[0181] Total nitrogen (TN) in the influent i ): 33mg / L

[0182] Inlet flow rate (Q) i ): 1750m 3 / h (has recovered from the shock and stabilized)

[0183] Nitrate nitrogen in effluent 6.5 mg / L

[0184] Preset C / N: 3.5

[0185] The current stable DO settings for each zone of the main aeration unit are: front zone 2.6 mg / L, middle zone 2.2 mg / L, and rear zone 0.8 mg / L.

[0186] Step S43 includes:

[0187] When the influent chemical oxygen demand is below the third threshold, the spatial proportion of the "high" oxygen zone is narrowed, and the spatial proportion of the "low" oxygen zone and "medium" oxygen zone is significantly expanded, so as to form a wide range of anoxic / aerobic alternating microenvironment in the aerobic unit, enhance simultaneous nitrification and denitrification, and provide an advantageous environment for short-cut nitrification and denitrification.

[0188] When the influent chemical oxygen demand is between the third and fourth thresholds, the spatial proportions of the "high", "medium" and "low" zones are maintained with significant differences and balance, so as to achieve the parallel and complementary functions of short-cut nitrification and denitrification, full-process nitrification and denitrification and simultaneous nitrification and denitrification in space, and to achieve efficient coupling of multiple denitrification mechanisms through gradient field morphology optimization.

[0189] When the influent chemical oxygen demand is higher than the fourth threshold, the proportion of the high-oxygen zone is increased while the proportion of the low-oxygen zone is reduced to ensure complete nitrification capacity under high organic load, and at the same time create strict denitrification conditions for the subsequent anoxic unit, ensuring the efficient operation of the entire nitrification and denitrification pathway.

[0190] Third threshold (COD1): 200 mg / L (to distinguish between low-carbon and medium-carbon)

[0191] Fourth threshold (COD2): 350 mg / L (to distinguish between medium and high carbon)

[0192] The system takes the average COD of the influent over the past 15 minutes. avg =245mg / L, to eliminate the interference of instantaneous fluctuations.

[0193] COD avg (245mg / L)>COD1 (200mg / L)

[0194] COD avg (245mg / L) <CODth2(350mg / L)

[0195] The system determines that the current influent is in the "medium carbon" range. Based on the preset mapping relationship, the system decides that the preferred nitrogen removal pathway to be strengthened is: "a composite pathway that is compatible with both short-cut nitrification and denitrification and full-process nitrification and denitrification".

[0196] After determining the composite pathway, the system fine-tunes the morphological parameters of the "high-medium-low" dissolved oxygen gradient field to better adapt to the biochemical requirements of the pathway.

[0197] The gradient pattern was optimized from the relatively loose “high (2.6)-medium (2.2)-low (0.8)” to the more precise “high (2.4)-medium (2.1)-low (0.8)”, which better meets the biochemical requirements of the complex denitrification pathway.

[0198] The system is based on the current decision-making "composite path" and real-time water output. The concentration (6.5 mg / L) is used to calculate the carbon source requirement for denitrification. The system's built-in carbon source dosing model, combined with the influent C / N ratio, target effluent TN, and denitrification efficiency, calculates the required carbon source for the effluent. If the temperature drops below the target, the carbon source dosage needs to be increased during the next anoxic period. Since the combined pathway needs to consider both the initial and subsequent denitrification stages, the system maintains a strategy of keeping both the first and second dosing points active.

[0199] The first addition point primarily provides a carbon source for denitrification and partially participates in anabolism. In a complex pathway, the demands of the preceding and following stages must be balanced.

[0200] The second addition point is mainly used to enhance denitrification during the anoxic period of the sequencing batch, which is key to deep nitrogen removal.

[0201] Depending on the additional removal required Volume (approximately 1.5 mg / L) and current flow rate (1750 m³) 3The calculated additional carbon source required (in terms of COD) is approximately 1.5 * 1750 / 1000 * 3.5 ≈ 9.2 kg COD / h.

[0202] The additional carbon source is added in pulses at the second dosing point. The system instructs the metering pump at the second dosing point to increase the dosing rate to the corresponding level during the 30-minute anoxic period. At the same time, the baseline dosing amount at the first dosing point remains unchanged.

[0203] After completing the above adjustments, the system enters a period of observation and fine-tuning.

[0204] Performance monitoring: During the subsequent 1-2 operating cycles (approximately 4-8 hours), focus on monitoring the NH4 content of the effluent. + -N、 And the changes in TN.

[0205] If NH4 is released from the water + An increase in -N indicates insufficient nitrification, and the system will increase the DO in the foreground.

[0206] If water comes out If the temperature does not decrease or even increases, it indicates insufficient denitrification, and the system may need to further adjust the carbon source ratio or increase the DO in the downstream zone.

[0207] If the effluent TN decreases steadily and meets the standard, the current path decision and parameter adjustment are confirmed to be effective, and the system will maintain this operating mode.

[0208] In this embodiment, after adjustment, the NH4 in the effluent... + -N remained stable below 0.8 mg / L. After 4 hours, the concentration dropped to 4.2 mg / L, and the effluent total nitrogen (TN) stabilized at around 1.8 mg / L. The system determined that the path decision and coordinated adjustment were successful and maintained this "composite path" operation mode until a significant change in the influent water quality triggered a new decision.

[0209] Step S44: Based on the real-time feedback of water temperature changes, total nitrogen concentration in the effluent, and microbial community characteristics, adjust the sludge return ratio, system sludge concentration, and sludge discharge strategy in a coordinated manner.

[0210] After completing the path optimization in step S43, the system enters the long-term stable operation phase. This step aims to address changes in the external environment (such as seasonal water temperature fluctuations) and internal state evolution (such as microbial community turnover), and to continuously optimize operating parameters through closed-loop feedback to maintain the long-term stability of the ultimate nitrogen removal efficiency.

[0211] Known background and real-time data:

[0212] Season and Environment: As the operating period enters November, the ambient temperature continues to drop.

[0213] Key real-time monitoring data:

[0214] Inlet water temperature (T) i Temperature: 14.2°C (24-hour average, showing a downward trend)

[0215] Total nitrogen (TN) in effluent: 2.1 mg / L (average over the last 4 hours)

[0216] System sludge concentration (MLSS): 4800 mg / L

[0217] Microbial community characteristics (weekly monitoring report): The total relative abundance of nitrifying bacteria (mainly ammonia oxidizing bacteria AOB and nitrite oxidizing bacteria NOB) was 18%, and the relative abundance of denitrifying bacteria was 12%. The report noted that the abundance of NOB decreased slightly compared to last week.

[0218] Specifically, please refer to Figure 4 The diagram shows a flowchart of step S44 of the MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to the present invention. Step S44 includes:

[0219] Step S441, water temperature adaptive control: When the water temperature is detected to be continuously below the third threshold, the winter operation mode is activated to increase the sludge concentration in the system and increase the total amount of carbon source added as needed;

[0220] The system detected that the water temperature had been below the low-temperature threshold T for 48 consecutive hours. l =15℃, and the trend forecast predicts that it will remain below this threshold for the next week. The system will automatically trigger and execute the "winter operation mode".

[0221] Sludge concentration increase control:

[0222] Understandably, to prevent a decrease in microbial activity due to low temperatures, it is necessary to increase biomass to maintain treatment capacity. The MLSS control target for winter operation mode is set at 5500 mg / L.

[0223] In this embodiment, the system immediately reduces the amount of excess sludge discharged. Through dynamic calculation, the discharge rate is gradually reduced from 90 m³ / d to 80 m³ / d. It is expected that through 3-5 days of net sludge growth, the MLSS will gradually increase from 4800 mg / L to the target value. The system simultaneously slightly increases the sludge return ratio to 85% to accelerate the redistribution and stabilization of sludge concentration.

[0224] Carbon source input compensation and regulation:

[0225] Understandably, low temperatures slow down microbial metabolism, reduce substrate utilization efficiency, and make denitrification rates more sensitive to temperature. Therefore, it is necessary to increase carbon sources to ensure sufficient denitrification.

[0226] The system detected a drop in water temperature and water output. There is an upward trend (from 4.2 mg / L to 5.8 mg / L). To compensate for the decrease in denitrification rate caused by low temperature, the system, based on the existing on-demand dosing mode, activates the water temperature compensation algorithm system. The second dosing point... The control setpoint was temporarily adjusted from 5.0 mg / L to 4.5 mg / L to trigger carbon source dosing earlier; simultaneously, the dosing pulse duration was extended from the original 30 minutes to 40 minutes upon triggering dosing. After this adjustment, the system observed improved effluent quality. The gradual decrease in concentration indicates that the denitrification process has been strengthened, achieving an adaptive match between the carbon source dosage and the actual biochemical requirements under low-temperature conditions.

[0227] In winter operation mode, the dissolved oxygen control range is optimized and adjusted (while also considering energy consumption):

[0228] Understandably, oxygen saturation concentration increases at low temperatures, and the activity of nitrifying bacteria is limited. Therefore, while ensuring nitrification efficiency, the DO setting can be appropriately reduced to save aeration energy consumption.

[0229] In this embodiment, the system performs minor optimization on the DO setting value of the main aeration unit.

[0230] Front-end partition: The target value was slightly reduced from 2.4 mg / L to 2.3 mg / L, with the allowable fluctuation range remaining at ±0.2 mg / L.

[0231] Mid-range zoning: The target value was slightly reduced from 2.1 mg / L to 2.0 mg / L, and the lower control limit was reduced from 2.0 mg / L to 1.9 mg / L.

[0232] For the later stage: the target value remains unchanged at 0.8 mg / L.

[0233] To ensure ammonia nitrogen removal rate (via real-time NH4) + Under the premise that the total power of the blower does not decrease (as verified by monitoring), a decrease of about 3-5% was observed in the total power of the blower.

[0234] Step S442, effluent feedback closed-loop control: Based on the real-time measurement value of the total nitrogen concentration in the effluent, the overall dissolved oxygen level of the main aeration aerobic unit and the total amount of external carbon source added are adjusted in a closed loop.

[0235] The system detected that the average TN (total nitrogen) in the effluent over four consecutive hours (2.1 mg / L) exceeded the target threshold TN. lim = 2.0 mg / L, triggering the effluent index feedback control program.

[0236] Recent data from system correlation analysis:

[0237] NH4 in the water + The fact that -N is stable below 0.5 mg / L indicates that the nitrification process is normal.

[0238] Out of water The increase in (nitrate + nitrite) from 4.2 mg / L to 5.8 mg / L suggests that the denitrification process may be limited.

[0239] The stable C / N ratio in the influent indicates that the carbon source is relatively sufficient.

[0240] The decrease in water temperature may be the main limiting factor for the denitrification rate (consistent with the judgment in step S441).

[0241] Based on the diagnosis, the system executes closed-loop regulation aimed at enhancing denitrification:

[0242] The system decision-making process mainly involves implementing the enhanced dosing during the anoxic period (second dosing point) of the sequencing unit, as this is a critical step in deep denitrification.

[0243] Dosage calculation: The system calculates the amount of additional material to be removed. Based on the volume and real-time flow rate, combined with the preset C / N ratio requirement, the carbon source requirement for this enhanced addition is dynamically calculated to be approximately 5-7 kg COD per cycle.

[0244] Dosing mode: The calculated carbon source is not added at a constant hourly flow rate, but is instead converted into a high-intensity "compensation pulse" that is injected at the start of the anoxic period of the next sequencing batch unit.

[0245] Optimize the anoxic environment: Adjust the DO in the downstream zone of the main aeration unit to 0.9 mg / L, and instruct the downstream anoxic / aerobic units to strengthen stirring and reduce micro-aeration during the anoxic period to ensure a more stringent anoxic environment.

[0246] Increase denitrification biomass: Slightly increase the sludge return ratio to 88%, returning more sludge containing denitrifying bacteria to the front of the system to increase their absolute number in the anoxic zone.

[0247] After implementing the above adjustments, the system will closely monitor the effluent for the next 6-12 hours. And TN. Observed The concentration gradually decreased to 4.5 mg / L, and the effluent TN decreased to 1.9 mg / L. When the TN remained below 2.0 mg / L for 6 consecutive hours, the system determined that this round of feedback adjustment was successful and maintained the adjusted parameters.

[0248] Step S443, Sludge Age Optimization and Control: Based on the analysis results of microbial community characteristics, dynamically adjust the sludge discharge volume to optimize the sludge age of the system and maintain the dominant position of functional microorganisms.

[0249] The system incorporates weekly microbial community monitoring reports for targeted regulation.

[0250] This week's report shows that the total abundance of nitrifying bacteria (Nitrospirota) (18%) is still within an acceptable range, but the abundance of nitrite-oxidizing bacteria (NOB) has decreased. This may be a result of the combined effects of low temperature, low dissolved oxygen (DO), and the system's recent tendency towards short-pathway nitrification. While this is beneficial for short-pathway nitrification and denitrification, the risk of nitrite accumulation due to excessive NOB suppression should be noted.

[0251] Figure 5 In this embodiment of the invention, after the multi-stage, multi-segment intelligent dissolved oxygen control method was stabilized, high-throughput sequencing results of the activated sludge microbial community showed that Pseudomonadota and Chloroflexota remained the dominant phyla throughout multiple consecutive sampling stages (e.g., III_5A to I_J). These two groups contain the vast majority of known key functional genera for nitrification, denitrification, simultaneous nitrification and denitrification, and carbon metabolism. Their stable dominance forms the microbial ecological foundation for the efficient nitrogen removal and carbon source utilization of this process. Throughout the entire operating cycle, key functional phyla closely related to the nitrogen cycle were successfully enriched and maintained stably. Among them, Nitrospirota, as the main carrier of anaerobic ammonia oxidation (Anammox) and partial nitrification processes, provides the possibility for deep nitrogen removal due to its stable presence.

[0252] Phylums such as Bacteroidota and Actinomycetota, which play important roles in the decomposition of recalcitrant organic matter and the formation of bacterial flocs, also account for a considerable proportion.

[0253] This indicates that the core microbial community structure remained highly stable from the early stages to the long-term stable operation period, proving that the dissolved oxygen gradient field and intelligent regulation strategy constructed in this invention can shape and maintain a stable microbial ecosystem dominated by composite denitrification function. This stable ecosystem makes the process highly resistant to shocks.

[0254] Figure 6This figure shows the annotation results of the nitrogen cycle database from the metagenomic sequencing of activated sludge in this invention. The height of the bars in the figure represents the number of sequences annotated to that functional gene category. The results indicate that the sludge microbial community possesses a strong genetic potential and complete metabolic pathway integrity for the complete reduction of nitrate / nitrite nitrogen to nitrogen gas. The annotation results also show a large number of functional genes related to assimilation of nitrate reduction, dissimilation of nitrate reduction, nitrification, and denitrification, such as glnA, nirS, nosZ, nmo, nirK, narH, ureC, and asnB. This directly confirms, at the molecular biological level, the coexistence and active microscopic mechanism of multiple nitrogen removal pathways—including short-cut nitrification / denitrification, full-process nitrification / denitrification, and simultaneous nitrification / denitrification—in the process of this invention.

[0255] By appropriately optimizing the sludge age and fine-tuning the microbial community structure while maintaining overall nitrification capacity (ensuring AOB), excessive NOB washing is avoided. After system calculation, the excess sludge discharge rate is further fine-tuned from 90 m³ / d in the winter operation mode to 80 m³ / d.

[0256] This measure aims to slightly extend the average sludge age of the system, providing a longer residence time for slower-growing nitrifying bacteria (including NOB) and stabilizing their population.

[0257] Due to the reduced discharge volume, the system's MLSS will increase more rapidly, helping to offset the impact of decreased activity at low temperatures. The system records this microbial characteristic and provides a reference for subsequent DO control. Sludge age optimization is a slow process. The system will combine effluent quality (especially nitrite concentration) and microbial community reports from the next 2-3 weeks to evaluate the effectiveness of this sludge discharge strategy adjustment and decide whether to proceed with further optimization.

[0258] Step S5 involves passing the wastewater through the inherent multi-stage reaction environment of the MSBR tank, and achieving deep denitrification through the synergistic effect of the multi-segment dissolved oxygen gradient environment and intelligent control algorithm within the main aeration aerobic unit.

[0259] It is understood that the aforementioned intelligent control algorithm refers to the specific methods for dynamically adjusting aeration intensity, sludge return ratio, sludge concentration, sludge discharge strategy, and carbon source addition strategy in steps S1-S4 above.

[0260] The MSBR system (treatment capacity 40,000 m³ / d) was evaluated as a complete cycle of 180 days of continuous and stable operation (covering summer, autumn, and winter). During this period, the influent water quality exhibited typical characteristics of urban wastewater with seasonal fluctuations (such as summer rainstorms and winter low temperatures). The daily average influent total nitrogen (TN) was 29.74 mg / L, and the water volume varied daily and fluctuated during holidays. The test results are shown in Table 1.

[0261] Table 1. Overall operating results of the MSBR extreme nitrogen removal method based on the present invention (180-day operating cycle)

[0262]

[0263] As shown in the table above, the MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent dissolved oxygen control of this invention significantly improves the system's treatment efficiency and operational performance, and reduces the COD of the effluent from the secondary MSBR process. Cr The main indicators such as BOD5 and ammonia nitrogen consistently meet the Class IV surface water standard, and the daily average total nitrogen can be stably controlled below 4 mg / L, ultimately reducing the unit treatment energy consumption to 0.28 kWh / m³. 3 The following improvements were achieved through optimized operation modes, resulting in a reduction of over 10% in overall energy consumption, approximately 30% in carbon source dosage, and significant reductions in energy and chemical consumption for filter backwashing. Operational data demonstrates that the multi-stage light oxygen-limited nitrogen removal technology employed in the technical upgrade program has surpassed the limitations of traditional activated sludge methods for total nitrogen removal. The results in controlling operating costs exceeded expectations, and system stability and reliability were significantly improved. This achieved the dual goals of enhanced treatment efficiency and reduced operating costs, resulting in significant environmental and economic benefits.

[0264] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen, characterized in that, include: Step S1: The main aerobic aeration unit of the MSBR reactor is physically separated along the water flow direction and divided into multiple independent aeration zones. Each aeration zone is equipped with an independent aeration pipeline and control valve. Step S2: Based on the influent water quality characteristics of the MSBR tank, each aeration unit is independently aerated to actively form and maintain a spatial gradient field of dissolved oxygen concentration that changes continuously from "high-medium-low" along the water flow direction in the main aerobic aeration unit, thereby creating a multi-segment dissolved oxygen environment in the main aerobic aeration unit. Step S3: Real-time monitoring of water quality parameters, water volume, water temperature, dissolved oxygen concentration, sludge concentration and microbial community characteristics in each zone of the main aeration aerobic unit in the influent and the MSBR reactor to form a multi-source monitoring dataset; Step S4: Based on the acquired multi-source monitoring dataset, dynamically adjust the aeration intensity, sludge return ratio, sludge concentration, sludge discharge strategy and carbon source addition strategy to synergistically regulate the short-cut nitrification-denitrification, full-process nitrification-denitrification and simultaneous nitrification-denitrification denitrification pathways. Step S5 involves passing the wastewater through the inherent multi-stage reaction environment of the MSBR tank, and achieving deep denitrification through the synergistic effect of the multi-segment dissolved oxygen gradient environment and intelligent control algorithm within the main aeration aerobic unit.

2. The MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to claim 1, characterized in that, In step S1, the physical partition is a flow guide wall with regularly spaced water passages, used to guide the water flow sequentially through each zone aeration unit to suppress the mixing of successive water flows.

3. The MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to claim 1, characterized in that, Step S4 includes: Step S41: Sequentially obtain the dissolved oxygen concentration of each zone along the influent flow direction, determine and dynamically adjust the aeration intensity of each zone to stabilize the dissolved oxygen spatial gradient. Step S42: Based on historical and real-time data, construct a dissolved oxygen trend prediction model, and based on the instantaneous change rate of influent flow and pollutant concentration monitored in real time, make a short-term shock risk assessment. Step S43: Based on the real-time influent carbon-nitrogen ratio and pollutant load, the morphological parameters of the "high-medium-low" gradient field are synergistically optimized. At the same time, based on the carbon source requirements of the dominant denitrification pathway and the real-time feedback of the effluent nitrate nitrogen concentration, an on-demand, intermittent carbon source addition strategy is generated and executed in the first anoxic unit and / or the second anoxic unit, and the short-cut nitrification-denitrification, full-process nitrification-denitrification, and simultaneous nitrification-denitrification denitrification pathways are synergistically controlled. Step S44: Based on the real-time feedback of water temperature changes, total nitrogen concentration in the effluent, and microbial community characteristics, adjust the sludge return ratio, system sludge concentration, and sludge discharge strategy in a coordinated manner.

4. The MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to claim 3, characterized in that, In step S42, the short-term shock risk assessment includes: If the instantaneous change rate of the influent flow rate or the concentration of key pollutants exceeds the first preset threshold, it is determined to be a mild shock, and the aeration intensity of each zone aeration unit is immediately increased according to the preset ratio. If the instantaneous change rate of the influent flow rate or the concentration of key pollutants exceeds the second preset threshold, it is determined to be a severe shock. At the same time, while increasing the aeration intensity, the control algorithm is switched to a higher frequency sampling and adjustment cycle.

5. The MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to claim 3, characterized in that, In step S42, the dissolved oxygen trend prediction model is constructed based on the theoretical oxygen consumption and the adaptive correction factor, wherein, The theoretical oxygen demand is determined based on carbon oxidation oxygen demand, nitrification oxygen demand, denitrification recovered oxygen equivalent, and a comprehensive correction factor for hydraulic effects. The adaptive correction factor is calculated based on the deviation between the predicted total oxygen demand (OTR) of the system and the actual oxygen demand (OTRa) of the system.

6. The MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to claim 3, characterized in that, Step S43 includes: When the influent chemical oxygen demand is below the third threshold, the spatial proportion of the "high" oxygen zone is narrowed, and the spatial proportion of the "low" oxygen zone and "medium" oxygen zone is significantly expanded, so as to form a wide range of anoxic / aerobic alternating microenvironment in the aerobic unit, enhance simultaneous nitrification and denitrification, and provide an advantageous environment for short-cut nitrification and denitrification. When the influent chemical oxygen demand is between the third and fourth thresholds, the spatial proportions of the "high", "medium" and "low" zones are maintained with significant differences and balance, so as to achieve the parallel and complementary functions of short-cut nitrification and denitrification, full-process nitrification and denitrification and simultaneous nitrification and denitrification in space, and to achieve efficient coupling of multiple denitrification mechanisms through gradient field morphology optimization. When the influent chemical oxygen demand exceeds the fourth threshold, the proportion of the high-oxygen zone is increased while the proportion of the low-oxygen zone is reduced to ensure complete nitrification capacity under high organic load, while creating strict denitrification conditions for subsequent anoxic units, thus ensuring the efficient operation of the entire nitrification-denitrification pathway.

7. The MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to claim 3, characterized in that, Step S44 includes: Step S441, water temperature adaptive control: When the water temperature is detected to be continuously below the third threshold, the winter operation mode is activated to increase the sludge concentration in the system and increase the total amount of carbon source added as needed. Step S442, effluent feedback closed-loop control: Based on the real-time measurement value of the total nitrogen concentration in the effluent, the overall dissolved oxygen level of the main aeration aerobic unit and the total amount of external carbon source added are adjusted in a closed loop. Step S443, Sludge Age Optimization and Control: Based on the analysis results of microbial community characteristics, dynamically adjust the sludge discharge volume to optimize the sludge age of the system and maintain the dominant position of functional microorganisms.

8. The MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to claim 7, characterized in that, The winter operation mode also includes adjusting the dissolved oxygen control range of each zone in the main aeration aerobic unit.

9. The MSBR extreme nitrogen removal method based on multi-stage and multi-segment intelligent control of dissolved oxygen according to claim 5, characterized in that, The comprehensive correction factor for hydraulic impact is determined based on the product of the flow load impact factor and the velocity / mixing efficiency factor, wherein, The flow load impact factor is determined based on the deviation between the current flow rate and the recent average flow rate; The flow rate / mixing efficiency factor is determined based on the actual flow rate or actual hydraulic residence time within the main aeration unit.

10. A wastewater treatment system employing the extreme nitrogen removal method based on multi-stage, multi-segment intelligent dissolved oxygen regulation as described in any one of claims 1-9, characterized in that, include: The main aerobic aeration unit is a rectangular tank with physical partitions along its length, dividing it into multiple independent aeration zones. Each aeration zone is equipped with its own aeration pipeline and control valves. A carbon source multi-point dosing unit includes at least one first dosing device disposed in a first anoxic unit or a second anoxic unit, and a second dosing device disposed downstream of the effluent of the main aeration aerobic unit in a first anoxic / aerobic unit or a second anoxic / aerobic unit. The multi-parameter online monitoring unit includes an online analyzer for monitoring influent water quality, dissolved oxygen sensors and sludge concentration meters installed in each zone of the main aeration aerobic unit; The intelligent control unit is communicatively connected to the multi-parameter online monitoring unit, the various air volume regulating valves of the partitioned main aeration aerobic unit, the carbon source multi-point dosing unit, and the sludge return and discharge device, in order to execute the extreme denitrification method based on multi-stage and multi-segment intelligent control of dissolved oxygen as described in any one of claims 1-9.

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