Aeration process quantitative evaluation method and system based on multi-region mass transfer model

Abstract

The invention relates to the technical field of sewage treatment, in particular to an aeration process quantitative evaluation method and system based on a multi-region mass transfer model. The aeration process quantitative evaluation method based on the multi-region mass transfer model comprises the following steps: S1, based on a physical structure and an operation mechanism of an aeration system, dividing the total volume involved in the aeration process into at least two physical regions with independent mass transfer characteristics in space; s2, determining key physical parameters of the oxygen mass transfer process based on the physical region, wherein the key physical parameters comprise equilibrium dissolved oxygen concentration; s3, calculating the oxygen transfer rate of the corresponding physical area based on the key physical parameters; s4, arithmetic addition is conducted on the oxygen transfer rates calculated in all the physical areas, the total oxygen transfer rate of the aeration system is obtained, the total oxygen transfer rate is the final quantitative evaluation result of the aeration process, and aeration can be accurately controlled through the total oxygen transfer rate.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method and system for quantitative evaluation of aeration processes based on a multi-zone mass transfer model. Background Technology

[0002] In municipal wastewater treatment, aeration is a crucial step in providing oxygen to aerobic microorganisms to remove organic matter and ammonia nitrogen, typically accounting for over 50% of the plant's total energy consumption. In the A² / O (anaerobic-anoxic-aerobic) process used in the third phase of the Chongqing Chayuan Wastewater Treatment Plant, the aerobic tank is the primary aeration site, and its operational efficiency directly affects whether the effluent quality meets standards and the overall operating costs of the plant. Figure 1 This describes the A² / O process flow and the functions of each component.

[0003] To achieve energy conservation, emission reduction, and stable nitrogen removal, precise quantitative evaluation of the aeration process efficiency is required. However, existing evaluation methods have significant limitations. Widely adopted industry standards, such as the American Society of Civil Engineers (ASCE) standard, are primarily based on a lumped-parameter first-order exponential model. This model treats the entire complex aeration process as a homogeneous black box, using a total volumetric mass transfer coefficient (kLa) for evaluation. The drawback of this method is that it fails to reflect the spatial variability present within the aerobic tanks of modern wastewater treatment processes (such as A² / O).

[0004] In actual operation, such as the aerobic tank of a tea plantation wastewater treatment plant, the flow direction is clearly divided into three functionally distinct zones: the inlet section, the intermediate section, and the outlet section. The inlet section primarily involves organic matter degradation with a high oxygen consumption rate, while the outlet section primarily involves ammonia nitrogen nitrification, exhibiting completely different oxygen requirements and objectives. Traditional lumped assessment methods conflate these functionally different zones, failing to reveal the true oxygen utilization efficiency of each zone. This results in crude assessments that cannot provide effective guidance for refined control of aeration systems (such as the "feedforward + feedback" zoned aeration control pursued by the tea plantation wastewater treatment plant). Furthermore, this method struggles to accurately quantify the impact of complex environmental factors such as air temperature and humidity on different mass transfer pathways (such as surface reoxygenation and underwater aeration).

[0005] Therefore, there is an urgent need for a more refined quantitative assessment method for aeration processes that can reflect the spatial heterogeneity of the process to meet the precise aeration control requirements of modern wastewater treatment plants. Summary of the Invention

[0006] The present invention aims to provide a quantitative evaluation method and system for aeration process based on a multi-region mass transfer model, which can accurately control aeration.

[0007] To address the aforementioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for quantitative evaluation of aeration processes based on a multi-region mass transfer model, comprising the following steps: S1: Based on the physical structure and operating mechanism of the aeration system, the total volume involved in the aeration process is spatially divided into at least two physical regions with independent mass transfer characteristics. S2: Determine the key physical parameters of the oxygen mass transfer process based on the physical region. The key physical parameters include the equilibrium dissolved oxygen concentration. S3: Calculate the oxygen transfer rate of the corresponding physical region based on key physical parameters; S4: Arithmetically sum the oxygen transfer rates calculated for all physical regions to obtain the total oxygen transfer rate of the aeration system. The total oxygen transfer rate is the final quantitative evaluation result of the aeration process.

[0008] By employing the aforementioned technical solution, the aeration system is divided into physical processes. This allows for the determination of the corresponding equilibrium dissolved oxygen concentration (OHSO) for different physical regions. The corresponding oxygen transfer rate is then calculated based on the OOH SO, and finally, a quantitative evaluation result is obtained based on the oxygen transfer rate. Through independent quantification of the aeration efficiency of each physical region, this method can clearly identify physical regions with uneven or inefficient aeration, providing direct data and feedback signals for achieving the "precise aeration" and "uniform and reasonable air volume distribution" sought by wastewater treatment plants like those in tea gardens. In this process, the mass transfer contribution of different mechanisms can be analyzed, and the final quantitative evaluation result is closer to physical reality and more accurate than traditional lumped parameter models, thus achieving precise control of aeration.

[0009] Optionally, when the aeration system is a surface aeration system, its physical area is divided into a droplet spray mass transfer zone and a liquid surface reoxygenation mass transfer zone; when the aeration system is a diffusion aeration system, its physical area is divided into a bubble dispersion mass transfer zone and a liquid surface reoxygenation mass transfer zone.

[0010] By adopting the above technical solutions, the contribution ratio of different mass transfer zones (such as spraying, liquid surface, and bubbles) to the overall performance can be clearly distinguished and quantified. This provides clear and quantifiable guidance for the design optimization of aeration equipment (e.g., whether to increase the spray volume or enhance liquid surface turbulence) and operation adjustment. It also allows for rapid adjustments to maintain stable operation.

[0011] Optionally, S2 includes: In the reoxygenation mass transfer zone at the liquid surface, the equilibrium dissolved oxygen concentration at the liquid surface is... The calculation reference temperature is determined to be the temperature of the main liquid.

[0012] Optionally, S2 includes: Equilibrium dissolved oxygen concentration in the droplet spray mass transfer zone The determination method includes using the wet-bulb temperature of the ambient air measured in real time as the equilibrium dissolved oxygen concentration at the droplet surface for calculation. The reference temperature.

[0013] By adopting the above technical solution, the "wet-bulb temperature of air" is creatively introduced as the calculation benchmark for the driving force of the droplet spraying area. This method has for the first time realized the scientific quantification of the influence of key environmental factors such as air temperature and humidity, and solved the problem that existing technologies cannot handle.

[0014] Optionally, S2 includes: Equilibrium dissolved oxygen concentration in the bubble dispersion mass transfer zone The calculation formula is: in, Represents the moment depth equilibrium dissolved oxygen concentration ; Equilibrium dissolved oxygen concentration under standard conditions ; Represents the moment depth Absolute pressure at the location; Represents saturated vapor pressure; Represents the moment depth The mole fraction of oxygen in the bubble; Represents standard atmospheric pressure; Represents standard temperature; Represents the mole fraction of oxygen in the atmosphere; With depth The change is determined by the material balance differential equation: in, Represents the volumetric mass transfer coefficient; Represents gas molar flux; Represents the horizontal cross-sectional area; This represents the average molar mass of the aeration gas. Represents the intrinsic time of the bubble dispersion mass transfer region Real-time dissolved oxygen concentration.

[0015] Optionally, S3 includes: The formula for calculating the oxygen transfer rate in the droplet spray mass transfer zone is: in, Represents the mass transfer region of droplet spraying at time The oxygen transfer rate; Represents the flow rate of the sprayed liquid; Represents the Murfried contact efficiency; Represents the mass transfer region of droplet spraying at time equilibrium dissolved oxygen concentration ; Represents the moment The dissolved oxygen concentration in the main liquid.

[0016] Optionally, a quantitative evaluation method for aeration processes based on a multi-zone mass transfer model further includes: The aeration process is evaluated by dividing it into time scales, including at least one of real-time time scale, process time scale, and operational time scale.

[0017] Optionally, the timescale assessment is performed by evaluating the total power consumption over the process cycle. Total influent ammonia nitrogen during the process cycle By integrating, the energy consumption of nitrification per cycle in the process can be calculated. : in, Represents the blower room at the point of integration. Total power; Represents the time of integration. The concentration of ammonia nitrogen in the influent; Represents the time of integration. Inflow rate; Represents the time of integration. The concentration of ammonia nitrogen in the effluent; Represents the time of integration. The outflow rate; Represents the time element; Represents the age of the sludge; Represents average water temperature; This represents the average pollution load.

[0018] Optionally, the final quantitative evaluation result in S4 also includes: By normalizing the oxygen transfer rate and corresponding aeration volume and energy consumption of each physical region, a set of spatially resolved evaluation indicators is obtained, including the power consumption per zone: in, Represents the unit power consumption of each zone; Represents the total number of physical regions; Represents the blower room at all times Total power; Represents physical region At any moment airflow; Represents all physical regions at time Total airflow; Represents physical region At any moment The total oxygen transfer rate.

[0019] Secondly, the present invention provides a quantitative evaluation system for aeration processes based on a multi-region mass transfer model, for implementing the quantitative evaluation method for aeration processes based on a multi-region mass transfer model described in the first aspect, comprising: a central processing unit, and a data acquisition unit and a result display unit electrically connected to the central processing unit respectively.

[0020] By adopting the above technical solution In summary, the present invention has at least the following beneficial technical effects: This method and system employs an LSTM model to predict the required aeration volume for wastewater treatment tanks based on historical data. Key parameters of the wastewater treatment tank are collected in real-time by sensors, and combined with a feedback control model, the required aeration volume adjustment is calculated. Finally, the required aeration volume is determined, enabling precise control of the blower and valves. The method includes data acquisition, LSTM prediction, feedback adjustment, blower opening control, and valve opening adjustment. This method effectively optimizes the aeration process, reduces energy consumption, and improves wastewater treatment efficiency, making it suitable for scenarios such as urban wastewater treatment plants. Attached Figure Description

[0021] Figure 1 A schematic diagram of the A² / O process flow and the functions of its various parts; Figure 2 This is a flowchart illustrating a quantitative evaluation method for aeration processes based on a multi-region mass transfer model, as described in an embodiment of this application. Figure 3 This is a schematic block diagram of a quantitative evaluation system for aeration processes based on a multi-region mass transfer model, as described in an embodiment of this application.

[0022] Figure 4 This is a system architecture and data flow diagram of a quantitative evaluation system for aeration processes based on a multi-region mass transfer model, as described in an embodiment of this application.

[0023] Explanation of reference numerals in the attached diagram: 1. Central processing unit; 2. Data acquisition unit; 3. Result display unit. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] This invention provides a method for quantitatively evaluating the aeration process in wastewater treatment.

[0026] refer to Figure 2 A quantitative evaluation method for aeration processes based on a multi-region mass transfer model includes the following steps: S1: Based on the physical structure and operating mechanism of the aeration system, the total volume involved in the aeration process is spatially divided into at least two physical regions with independent mass transfer characteristics.

[0027] The aeration system is either a surface aeration system or a diffusion aeration system (such as a tea garden wastewater treatment plant).

[0028] For surface aeration systems, the physical area is divided into a droplet spray mass transfer zone and a surface reoxygenation mass transfer zone. For diffusion aeration systems, the physical area is divided into a bubble dispersion mass transfer zone and a surface reoxygenation mass transfer zone. Furthermore, based on process function, the bubble dispersion mass transfer zone is further divided into multiple independent evaluation areas such as the aerobic tank inlet section, intermediate section, and outlet section.

[0029] S2: Determine the key physical parameters of the oxygen mass transfer process based on the physical region, including the equilibrium dissolved oxygen concentration.

[0030] During aeration, the equilibrium dissolved oxygen concentration is the driving force for mass transfer in the corresponding physical region of the aeration system.

[0031] When the aeration system is a surface aeration system, the equilibrium dissolved oxygen concentration in its droplet spray mass transfer zone is... The determination method includes using the wet-bulb temperature of the ambient air measured in real time as the equilibrium dissolved oxygen concentration at the droplet surface for calculation. The reference temperature, not the temperature of the bulk liquid.

[0032] When the aeration system is a diffusion aeration system, the equilibrium dissolved oxygen concentration in its bubble diffusion mass transfer zone is... The methods for determining this include: balancing the dissolved oxygen concentration. The solution is established as a function of liquid depth, which takes into account both the hydrostatic pressure at that depth and the change in the mole fraction of oxygen within the bubble due to oxygen dissolution during the bubble's ascent. The equilibrium dissolved oxygen concentration at that depth is... The calculation formula is: in, Represents the moment depth equilibrium dissolved oxygen concentration ; Equilibrium dissolved oxygen concentration under standard conditions ; Represents the moment depth Absolute pressure at the location; Represents saturated vapor pressure; Represents the moment depth The mole fraction of oxygen in the bubble; Represents standard atmospheric pressure; Represents standard temperature; This represents the mole fraction of oxygen in the atmosphere.

[0033] With depth The change is determined by the material balance differential equation: in, Represents the volumetric mass transfer coefficient; Represents gas molar flux; Represents the horizontal cross-sectional area; The average molar mass of the aeration gas (air); Represents the intrinsic time of the bubble dispersion mass transfer region Real-time dissolved oxygen concentration.

[0034] Whether it's a surface aeration system or a diffusion aeration system, the equilibrium dissolved oxygen concentration at the liquid surface is maintained in the reoxygenation mass transfer zone. The calculation reference temperature is determined to be the temperature of the main liquid.

[0035] S3: Calculate the oxygen transfer rate (OTR) of the corresponding physical region based on key physical parameters.

[0036] When the aeration system is a surface aeration system, the formula for calculating the oxygen transfer rate in its droplet spray mass transfer zone is: in, Represents the mass transfer region of droplet spraying at time The oxygen transfer rate; Represents the flow rate of the sprayed liquid; Represents the Murfried contact efficiency; Represents the mass transfer region of droplet spraying at time equilibrium dissolved oxygen concentration ; Represents the moment The dissolved oxygen concentration in the main liquid.

[0037] When the aeration system is a diffusion aeration system, the oxygen transfer rate in its bubble diffusion mass transfer zone is obtained by integrating the local mass transfer rate that varies with depth throughout the entire region.

[0038] Regardless of whether it is a surface aeration system or a diffusion aeration system, the oxygen transfer rate in the liquid surface reoxygenation mass transfer zone... The calculation is performed based on the liquid surface area, surface mass transfer coefficient, and mass transfer driving force calculated based on the bulk liquid temperature.

[0039] S4: Arithmetically sum the oxygen transfer rates calculated for all physical regions to obtain the total oxygen transfer rate (OTR) of the aeration system. Total The total oxygen transfer rate is the final quantitative evaluation result of the aeration process.

[0040] A quantitative evaluation method for aeration processes based on a multi-region mass transfer model further includes: dividing the aeration process into multiple time scales for evaluation during the quantitative evaluation process. The time scales include at least a real-time time scale, a process time scale, and an operational time scale.

[0041] Real-time timescales are evaluated in minutes to obtain the instantaneous operating status and efficiency of the system. Process timescales are evaluated in hours, in conjunction with hydraulic retention time (HRT), to assess the overall effectiveness of a complete treatment cycle. Operational timescales are evaluated in days or weeks, in conjunction with sludge age (SRT), to analyze long-term performance trends and establish an operational baseline.

[0042] Among them, the time-scale assessment is based on the total power consumption during the process cycle. Total influent ammonia nitrogen during the process cycle By integrating, the energy consumption of nitrification per cycle in the process can be calculated. : in, Represents the blower room at the point of integration. Total power; Represents the time of integration. The concentration of ammonia nitrogen in the influent; Represents the time of integration. Inflow rate; Represents the time of integration. The concentration of ammonia nitrogen in the effluent; Represents the time of integration. The outflow rate; Represents the time element; Represents the age of the sludge; Represents average water temperature; This represents the average pollution load.

[0043] A quantitative evaluation method for aeration processes based on a multi-region mass transfer model, wherein the final quantitative evaluation result in S4 further includes: obtaining a set of spatially resolved evaluation indicators by normalizing the oxygen transfer rate and corresponding aeration volume and energy consumption of each physical region, including the power consumption per zone. in, Represents the unit power consumption of each zone; Represents the total number of physical regions; Represents the blower room at all times Total power; Represents physical region At any moment airflow; Represents all physical regions at time Total airflow; Represents physical region At any moment The total oxygen transfer rate.

[0044] This invention also provides a quantitative evaluation system for wastewater treatment aeration processes.

[0045] refer to Figure 3-4 A quantitative evaluation system for aeration processes based on a multi-region mass transfer model includes: a central processing unit 1, and a data acquisition unit 2 and a result display unit 3, which are electrically connected to the central processing unit 1 respectively.

[0046] The data acquisition unit 2 includes multiple sensors deployed in different physical areas. Each sensor is used to collect real-time operating data such as dissolved oxygen concentration, air flow, pressure, temperature, and water quality.

[0047] Central processing unit 1 is used to execute the above-described quantitative evaluation method for wastewater treatment aeration processes. Result display unit 3 is used to display the final quantitative evaluation results digitally or graphically.

[0048] The various variations and specific examples of the methods provided in the above embodiments are applicable to the wastewater treatment aeration process quantitative evaluation system of this embodiment. Through the foregoing detailed description of the wastewater treatment aeration process quantitative evaluation method, those skilled in the art can clearly understand the implementation method of the wastewater treatment aeration process quantitative evaluation system of this embodiment. For the sake of brevity, it will not be described in detail here.

[0049] The above description of the embodiments is only used to provide a detailed introduction to the technical solution of the present invention. However, the description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention, and should not be construed as a limitation of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for quantitatively evaluating aeration processes based on a multi-region mass transfer model, characterized in that, Includes the following steps: S1: Based on the physical structure and operating mechanism of the aeration system, the total volume involved in the aeration process is spatially divided into at least two physical regions with independent mass transfer characteristics. S2: Determine the key physical parameters of the oxygen mass transfer process based on the physical region. The key physical parameters include the equilibrium dissolved oxygen concentration. S3: Calculate the oxygen transfer rate of the corresponding physical region based on key physical parameters; S4: Arithmetically sum the oxygen transfer rates calculated for all physical regions to obtain the total oxygen transfer rate of the aeration system. The total oxygen transfer rate is the final quantitative evaluation result of the aeration process.

2. The quantitative evaluation method for aeration processes based on a multi-region mass transfer model as described in claim 1, characterized in that, When the aeration system is a surface aeration system, its physical area is divided into a droplet spray mass transfer zone and a liquid surface reoxygenation mass transfer zone; when the aeration system is a diffusion aeration system, its physical area is divided into a bubble dispersion mass transfer zone and a liquid surface reoxygenation mass transfer zone.

3. The quantitative evaluation method for aeration processes based on a multi-region mass transfer model as described in claim 2, characterized in that, S2 includes: In the reoxygenation mass transfer zone at the liquid surface, the equilibrium dissolved oxygen concentration at the liquid surface is... The calculation reference temperature is determined to be the temperature of the main liquid.

4. The quantitative evaluation method for aeration processes based on a multi-region mass transfer model as described in claim 3, characterized in that, S2 includes: Equilibrium dissolved oxygen concentration in the droplet spray mass transfer zone The determination method includes using the wet-bulb temperature of the ambient air measured in real time as the equilibrium dissolved oxygen concentration at the droplet surface for calculation. The reference temperature.

5. The quantitative evaluation method for aeration processes based on a multi-region mass transfer model as described in claim 3, characterized in that, S2 includes: Equilibrium dissolved oxygen concentration in the bubble dispersion mass transfer zone The calculation formula is: in, Represents the moment depth equilibrium dissolved oxygen concentration ; Equilibrium dissolved oxygen concentration under standard conditions ; Represents the moment depth Absolute pressure at the location; Represents saturated vapor pressure; Represents the moment depth The mole fraction of oxygen in the bubble; Represents standard atmospheric pressure; Represents standard temperature; Represents the mole fraction of oxygen in the atmosphere; With depth The change is determined by the material balance differential equation: in, Represents the volumetric mass transfer coefficient; Represents gas molar flux; Represents the horizontal cross-sectional area; This represents the average molar mass of the aeration gas. Represents the intrinsic time of the bubble dispersion mass transfer region Real-time dissolved oxygen concentration.

6. The quantitative evaluation method for aeration processes based on a multi-region mass transfer model as described in claim 4, characterized in that, S3 includes: The formula for calculating the oxygen transfer rate in the droplet spray mass transfer zone is: in, Represents the mass transfer region of droplet spray at time The oxygen transfer rate; Represents the flow rate of the sprayed liquid; Represents the Murfried contact efficiency; Represents the mass transfer region of droplet spraying at time equilibrium dissolved oxygen concentration ; Represents the moment The dissolved oxygen concentration in the main liquid.

7. A method for quantitatively evaluating an aeration process based on a multi-region mass transfer model as described in any one of claims 1-6, characterized in that, Also includes: The aeration process is evaluated by dividing it into time scales, including at least one of real-time time scale, process time scale, and operational time scale.

8. The quantitative evaluation method for aeration processes based on a multi-region mass transfer model as described in claim 7, characterized in that, The timescale assessment is based on the total power consumption over the process cycle. Total influent ammonia nitrogen during the process cycle By integrating, the energy consumption of nitrification per cycle in the process can be calculated. : in, Represents the blower room at the point of integration. Total power; Represents the time of integration. The concentration of ammonia nitrogen in the influent; Represents the time of integration. Inflow rate; Represents the time of integration. The concentration of ammonia nitrogen in the effluent; Represents the time of integration. The outflow rate; Represents the time element; Represents the age of the sludge; Represents average water temperature; This represents the average pollution load.

9. The quantitative evaluation method for aeration processes based on a multi-region mass transfer model as described in claim 8, characterized in that, The final quantitative evaluation results in S4 also include: By normalizing the oxygen transfer rate and corresponding aeration volume and energy consumption of each physical region, a set of spatially resolved evaluation indicators is obtained, including the power consumption per zone: in, Represents the unit power consumption of each zone; Represents the total number of physical regions; Represents the blower room at all times Total power; Represents physical region At any moment airflow; Represents all physical regions at time Total airflow; Represents physical region At any moment The total oxygen transfer rate.

10. A quantitative evaluation system for aeration processes based on a multi-region mass transfer model, characterized in that, The method for quantitative evaluation of aeration process based on a multi-region mass transfer model as described in any one of claims 1-9 includes: a central processing unit (1), and a data acquisition unit (2) and a result display unit (3) electrically connected to the central processing unit (1).

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