Low-carbon high-efficiency biochemical system control system

Abstract

The utility model provides a low-carbon high-efficiency biochemical system control system. The low-carbon high-efficiency biochemical system control system comprises an internal reflux control module, a carbon source adding module and a precise aeration module, the internal reflux control module is used for refluxing nitrate nitrogen required to be denitrified to the anoxic tank for denitrification; the carbon source adding module is used for giving the current required dosage through online nitrate nitrogen instruments arranged in an anoxic tank and an aeration tank according to dynamic nitrate nitrogen value comparison and variation trend comparison at the tail end of the anoxic tank; and the accurate aeration module reads the real-time numerical value of ammonia nitrogen at the tail end of the aeration tank, performs mean value calculation on the numerical value in each period, performs difference value calculation on the average value of ammonia nitrogen in the current period and the average value of ammonia nitrogen in the last period, and reaches the numerical value of dissolved oxygen through frequency adjustment of an aeration fan to run in a required operation interval. The control method of the low-carbon high-efficiency biochemical system aims to realize low-carbon high-efficiency accurate control of the biochemical system, aeration as required, addition of an external carbon source and control of internal reflux.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment, and in particular to a low-carbon, high-efficiency biochemical system control system. Background Technology

[0002] Currently, most municipal wastewater treatment plants rely on manual control of their biochemical systems. This requires experienced operators to make adjustments based on changes in water quality and quantity. Moreover, these adjustments are mostly based on experience and lack precision. Furthermore, there are instances where manual responses are not timely. This can lead to waste of energy and chemicals and may even cause production accidents. Therefore, automated and intelligent control is the future trend.

[0003] Biological nitrogen removal technology is based on nitrification, denitrification, low-DO (dissolved oxygen) nitrification, and simultaneous nitrification-denitrification (SND). Traditional biological nitrogen removal processes suffer from unstable treatment effects due to lag in regulation and slow response, as well as problems such as high reagent consumption and energy waste due to extensive management and loose control. Nitrifying bacteria proliferate slowly, making it difficult to maintain a high biological concentration, especially in cold winters when the system's HRT (hydraulic retention time) is long, requiring a large aeration tank and increasing investment and operating costs. To maintain a high biological concentration and achieve good denitrification, the system must simultaneously process sludge and nitrified liquor, increasing power consumption and operating costs. The system has weak shock resistance; high concentrations of NH3-N and NO2- in wastewater inhibit the growth of nitrifying bacteria. The acidity generated during nitrification requires neutralization with alkali, which not only increases treatment costs but may also cause secondary pollution.

[0004] Therefore, the key to the operation and management of biochemical reactors lies in the precise control of details. In the face of fluctuations in water quality and quantity, the operation strategy should be flexibly adjusted, and the control variables should include the air supply of the blower, the amount of carbon source added, and the internal return flow rate. This can effectively cope with changes and ensure the quality of the effluent. Utility Model Content

[0005] This invention provides a low-carbon, high-efficiency biochemical system control system, which solves the problem of automating parameter assignment and control of biochemical reactor (AAO) control variables with the ultimate goal of achieving feedback control. The control variables include fan air supply, carbon source dosage, and internal recirculation flow. The technical solution is as follows:

[0006] A low-carbon, high-efficiency biochemical system control system is disclosed. This control system is installed in the biochemical reaction tank of a wastewater treatment plant. The biochemical reaction tank includes an inlet end for sequential biochemical treatment of wastewater, an anaerobic tank, an anoxic tank, an aeration tank, a sedimentation tank, and an outlet end. The control system includes an internal recirculation control module, a carbon source dosing module, and a precision aeration module. The internal recirculation control module recirculates the nitrate nitrogen requiring denitrification back to the anoxic tank for denitrification. The carbon source dosing module, using online nitrate nitrogen meters installed in the anoxic and aeration tanks, determines the required dosage based on comparisons of dynamic nitrate nitrogen values ​​and trends at the end of the anoxic tank. The precision aeration module adjusts the frequency of the aeration blowers to ensure dissolved oxygen levels are within the appropriate operating range.

[0007] An online total nitrogen meter, an online ammonia nitrogen meter, an online COD meter, and an online biochemical flow meter Q1 are installed at the inlet of the biochemical reaction tank. The total nitrogen, ammonia nitrogen, and COD in the inlet of the biochemical reaction tank are monitored online, and the inlet flow rate of the biochemical reaction tank is measured in real time.

[0008] The anoxic tank is equipped with online ORP, first online dissolved oxygen, and first online nitrate nitrogen meters; the online monitoring instruments monitor the ORP, dissolved oxygen, and nitrate nitrogen levels at the end of the anoxic tank in real time.

[0009] The aeration tank is equipped with a pH meter, a second online nitrate nitrogen meter, an online ammonia nitrogen meter, a sludge concentration meter, a second online dissolved oxygen and temperature sensor. The corresponding instruments monitor and provide feedback on the pH, nitrate nitrogen, ammonia nitrogen, dissolved oxygen, temperature and sludge concentration at the end of the aeration tank in real time.

[0010] The sedimentation tank is equipped with an online total nitrogen meter, an online ammonia nitrogen meter, and an online COD meter to monitor the total nitrogen, ammonia nitrogen, and COD in the effluent from the biological treatment system online.

[0011] It also includes an accounting system, which is used to automatically calculate the required air volume and carbon source based on the online monitoring instrument values, and to automatically calculate the nitrification liquid return flow based on the influent flow rate, online total nitrogen in the influent and total nitrogen in the effluent.

[0012] It also includes a big data simulation analysis and calculation system, which uses the fan air supply, carbon source addition, and internal return flow control as control variables and implements control through a feedback system.

[0013] The precision aeration module reads the real-time ammonia nitrogen value at the end of the aeration tank, calculates the average value for each cycle, and calculates the difference between the average ammonia nitrogen value of the current cycle and the average ammonia nitrogen value of the previous cycle. The result is ΔNH3-N. Based on the absolute value of ΔNH3-N, |ΔNH3-N|, the range of dissolved oxygen that should be maintained is determined. The frequency of the aeration blower is adjusted to ensure that the dissolved oxygen value is within the range of the required operating range.

[0014] The internal recirculation control module calculates the corresponding internal recirculation ratio based on the relationship between the influent flow rate, the online total nitrogen in the influent, and the total nitrogen in the effluent. It also calculates the relationship coefficient between the frequency and flow rate of the internal recirculation pump used on site, and outputs the internal recirculation frequency according to the required internal recirculation flow rate to control the internal recirculation flow rate.

[0015] During the initial startup of the control system, the initial values ​​of DO, carbon source dosage, and internal return flow are assigned based on the analysis of historical data.

[0016] The low-carbon, high-efficiency biochemical system control system aims to achieve low-carbon, high-efficiency, and precise control of the biochemical system, enabling on-demand aeration, addition of external carbon sources, and control of internal reflux.

[0017] This utility model has the following beneficial effects:

[0018] (1) In the low-carbon biochemical system control system described in this utility model, the formation of aerobic and hypoxic microenvironment in microbial flocs is closely related to the dissolved oxygen concentration. The average dissolved oxygen in the aerobic tank is controlled at 1 to 1.5 mg / L, which is only about 50% of the theoretical value of dissolved oxygen (2 mg / L) in the traditional activated sludge process.

[0019] (2) This utility model adjusts the carbon source addition ratio in a timely manner according to the feedback value, so as to achieve the effect of adding carbon source as needed and saving carbon source.

[0020] (3) The frequency of the internal return pump is controlled by the periodic output of the calculation results. Before the use of this system, the internal return of the sewage treatment plant adopted a fixed frequency return, which was set at 40Hz. After the system is put into operation, the frequency of the two internal return pumps in a single series will operate between 20 and 40Hz depending on the influent flow rate (Q1), the influent online total nitrogen (TN), and the effluent total nitrogen (TNe). The average operating frequency is 30Hz, the effluent total nitrogen is stably up to standard, and the power consumption is reduced by ~25%. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the control system of the low-carbon, high-efficiency biochemical system. Detailed Implementation

[0022] like Figure 1 As shown, the low-carbon, high-efficiency biochemical system control system is installed in the biochemical reaction tank section of the wastewater treatment plant. The wastewater treatment plant biochemical reaction tank includes an inlet end for sequential biochemical treatment of wastewater, an anaerobic tank, an anoxic tank, an aeration tank, a sedimentation tank, and an outlet end. The low-carbon, high-efficiency biochemical system control system includes:

[0023] The internal recirculation control module calculates the corresponding internal recirculation ratio based on the relationship between the influent flow rate, the online total nitrogen in the influent, and the total nitrogen in the effluent. It also calculates the relationship coefficient between the frequency and flow rate of the internal recirculation pump used on site, and outputs the internal recirculation frequency according to the required internal recirculation flow rate to control the internal recirculation flow rate.

[0024] The carbon source dosing module is crucial because the total nitrogen in the effluent from the biological reaction tank is primarily composed of nitrate nitrogen (nitrate form). Controlling the nitrate nitrogen level in the effluent effectively ensures the total nitrogen level. Changes in the carbon source dosage and the amount of internal recirculation flow directly affect the effluent nitrate nitrogen. Online nitrate meters are installed in both the anoxic and aeration tanks. Based on the comparison of dynamic nitrate nitrogen values ​​and trends in the anoxic and aeration tanks, the program adjusts the internal recirculation flow and the required dosage, achieving precise control of the carbon source dosage.

[0025] The precision aeration module, connected to the aeration tank via a blower adjustment module, effectively resolves the redox relationship in the microbial removal of COD, ammonia nitrogen, and TN in wastewater treatment, achieving an organic balance between redox and TN. This precision aeration module measures the aeration in the biochemical reaction tank, controlling the aeration intensity based on ammonia nitrogen treatment levels. It generally meets both COD and ammonia nitrogen removal requirements simultaneously, while also considering some TP (total phosphorus) removal. In this project, the aeration module is controlled based on ammonia nitrogen treatment as the indicator. Ammonia nitrogen is positively correlated with dissolved oxygen levels, while nitrate nitrogen is inversely correlated. Therefore, by adding an online ammonia nitrogen meter to the aeration tank, the process control program can promptly detect ammonia nitrogen changes based on the online feedback signal. The program automatically adjusts the dissolved oxygen tracking range and corresponding target value, and adjusts the airflow variable value of the aeration blower in real time. The dissolved oxygen is set between 0.5 and 5 mg / L (the upper limit is controlled based on the ORP at the end of the anoxic tank to avoid disrupting the anoxic environment). This ensures that COD, ammonia nitrogen, and nitrate nitrogen all continuously meet the standards with a safety margin even under low dissolved oxygen conditions.

[0026] It also includes a recording and analysis system, with online monitoring instruments installed at the inlet, anoxic tank, aeration tank, and sedimentation tank for data collection;

[0027] An online total nitrogen meter, an online ammonia nitrogen meter, an online COD meter, and an online biochemical flow meter Q1 are installed at the inlet of the biochemical reaction tank. The total nitrogen, ammonia nitrogen, and COD in the inlet of the biochemical reaction tank are monitored online, and the inlet flow of the biochemical reaction tank is measured in real time. The monitored and measured data serve as the control basis data for the control system of the low-carbon and high-efficiency biochemical system.

[0028] An online ORP, first online dissolved oxygen, and first online nitrate nitrogen meter are installed in the anoxic tank. The online monitoring instruments monitor the ORP, dissolved oxygen, and nitrate nitrogen values ​​at the end of the anoxic tank in real time. The real-time values ​​serve as the basic control data for the low-carbon and high-efficiency biochemical system control system.

[0029] The aeration tank is equipped with a pH meter, a second online nitrate nitrogen meter, an online ammonia nitrogen meter, a sludge concentration meter, a second online dissolved oxygen and temperature sensor. The corresponding instruments monitor and provide feedback on the pH, nitrate nitrogen, ammonia nitrogen, dissolved oxygen, temperature and sludge concentration at the end of the aeration tank in real time. The real-time values ​​serve as the control basis data for the low-carbon and high-efficiency biochemical system control system.

[0030] The sedimentation tank is equipped with online total nitrogen meters, online ammonia nitrogen meters, and online COD meters for the effluent. The total nitrogen, ammonia nitrogen, and COD in the effluent from the biological treatment system are monitored online, and the measured data serve as the basic control data for the low-carbon, high-efficiency biological treatment system control system.

[0031] It also includes an accounting system that, based on nitrification, denitrification, low-DO nitrification, and simultaneous nitrification-denitrification (SND), automatically quantifies and adjusts the operating parameters of the biological reactor to achieve intelligent operation. The automated design and calculation of the biological reactor's parameters are fundamental, such as automatically calculating the required airflow and carbon source based on online monitoring instrument readings, and automatically calculating the nitrified liquor return flow rate based on data such as influent flow rate, online total nitrogen in the influent, and total nitrogen in the effluent.

[0032] It also includes a big data simulation and analysis system, a series of activated sludge models based on COD and nitrogen removal theories such as nitrification-denitrification and simultaneous nitrification-denitrification; and controls the system through a feedback system using the blower air supply, carbon source dosage, and internal return flow as control variables.

[0033] This system is based on the existing biochemical reactor (AAO) of the wastewater treatment plant. It achieves automated and intelligent control by monitoring the values ​​of online COD, online total nitrogen, online ammonia nitrogen, influent flow rate, ORP in the anoxic tank, nitrate nitrogen at the end of the anoxic tank, dissolved oxygen (temperature) at the end of the aeration tank, ammonia nitrogen at the end of the aeration tank, nitrate nitrogen at the end of the aeration tank, and online COD, online total nitrogen, and online ammonia nitrogen in the effluent. In the initial stage of system startup, the initial values ​​of DO, carbon source dosage, and internal return flow are assigned based on the analysis of historical data. During operation, the system continuously and automatically adjusts itself with the key effluent indicators as the control boundary.

[0034] In the embodiments, the specific implementation of this utility model will be further described below with reference to the embodiments.

[0035] A wastewater treatment plant is designed with a total treatment capacity of 100,000 m³. 3 / d, the biochemical trench section is divided into 4 series, with one series selected as a pilot project. The design scale of this series of biochemical trenches is 25,000 m³. 3 / d, the actual influent water quality and the implemented effluent water quality indicators of the project are shown in Table 1.

[0036] Table 1. Actual influent water quality and effluent water quality standards of a wastewater treatment plant project:

[0037]

[0038] According to the control system requirements, online monitoring instruments are needed for influent COD, influent total nitrogen, influent ammonia nitrogen, influent flow rate, anoxic tank ORP, anoxic tank terminal nitrate nitrogen, aeration tank terminal dissolved oxygen (temperature), aeration tank terminal ammonia nitrogen, aeration tank terminal nitrate nitrogen, effluent online COD, effluent online total nitrogen, and effluent online ammonia nitrogen. These instruments should be connected to the aeration blower frequency control (aeration electric valve) interface, carbon source dosing pump control, and internal return pump frequency control interface.

[0039] Precision aeration module:

[0040] It is necessary to read the following data from the aeration tank: online ammonia nitrogen meter and second online dissolved oxygen real-time value;

[0041] The specific control process is as follows:

[0042] The water plant has a corresponding blower for this biological ditch and an electric valve (regulating type) is installed on the main aeration pipeline. The control is carried out in two ways: the required dissolved oxygen can be controlled by the frequency of the blower, and the dissolved oxygen can also be controlled by the opening degree of the electric valve (regulating type).

[0043] During initial commissioning, the water plant's operating conditions were used as the starting point. After commissioning, the real-time ammonia nitrogen (NH3-N) values ​​at the end of the aeration tank were read for calculation. The average value for each cycle was calculated, and then the difference between the average ammonia nitrogen value of the current cycle and the average ammonia nitrogen value of the previous cycle was calculated. Based on the magnitude of the difference, the appropriate operating range for dissolved oxygen (DO) was determined. The dissolved oxygen value was kept within the appropriate operating range by adjusting the frequency of the aeration blower or by adjusting the electric valve (regulating type). When it was necessary to adjust the dissolved oxygen range upward, the blower frequency was increased or the opening of the electric valve (regulating type) was increased. When it was necessary to adjust the dissolved oxygen range downward, the blower frequency was decreased or the opening of the electric valve (regulating type) was decreased. After on-site commissioning, the dissolved oxygen could be brought to the required operating range within 30 minutes, and the ammonia nitrogen in the effluent always met the effluent standard requirements.

[0044] The system automatically judged the changes in ammonia nitrogen and dissolved oxygen during the process of ammonia nitrogen levels rising from 0.04 mg / L to 0.14 mg / L and then to 0.19 mg / L at the end of the aeration tank. It promptly adjusted the dissolved oxygen (DO) operating range from 1.3–1.7 mg / L to 1.7–2.1 mg / L and then to 2.1–2.5 mg / L. After the DO operating range was adjusted, the ammonia nitrogen level gradually decreased, and the DO operating range also gradually decreased. This not only saved operating power consumption but also prevented the effluent ammonia nitrogen from exceeding the standard.

[0045] The carbon source dosing module needs to read data from the online biochemical flow meter at the inlet and the first online nitrate meter in the anoxic tank; the specific control process is as follows:

[0046] This system controls the addition of carbon source in real time based on the reading of the first online nitrification meter at the end of the anoxic tank. The system is set with the minimum and recommended control values ​​of the first online nitrification meter. The values ​​are given based on the water plant's original operating experience and process principles. When the real-time value is between the minimum and recommended control values, the original addition is maintained. When the real-time value is less than the minimum value, the carbon source addition is reduced proportionally. When the real-time value is greater than the recommended control value, the carbon source addition is increased proportionally. During the initial commissioning, the water plant's operating conditions are used as the starting point. The system automatically controls the addition of carbon source according to the changes in real-time values, achieving the effect of adding carbon source on demand.

[0047] The internal reflux module needs to read data from the online total nitrogen meter and the online biochemical flow meter at the inlet end; the specific control process is as follows:

[0048] The internal recirculation ratio is calculated based on the relationship between the influent biochemical flow rate (Q1), the influent online total nitrogen (TN), and the effluent total nitrogen (TNe). The relationship coefficient between the frequency and flow rate of the internal recirculation pump used on-site is then calculated. The internal recirculation frequency is output according to the required internal recirculation flow rate to control the internal recirculation flow rate. The wastewater treatment plant has a design capacity of 100,000 m³ / h. 3 Before using this system, the internal recirculation was all fixed-frequency recirculation, with a set frequency of 40Hz. After this system was put into operation, the frequency of the two internal recirculation pumps in each series will operate between 20 and 40Hz depending on the influent flow rate (Q1), the influent online total nitrogen (TN), and the effluent total nitrogen (TNe). The average operating frequency is 30Hz, and the effluent total nitrogen index has not exceeded the standard. While meeting the denitrification requirements, it saves power consumption.

[0049] For low-carbon and high-efficiency biochemical control systems, the accuracy of instruments is the foundation for the implementation of the system. The entire control system needs to operate based on the real-time feedback of the corresponding instruments. Therefore, after the system is implemented, attention should be paid to the regular maintenance and calibration of the instruments to ensure the accuracy of the instrument monitoring values. On this basis, the control system can accurately, timely, stably and precisely control the biochemical system, and ultimately achieve low-carbon and high-efficiency control of the biochemical system.

[0050] The described low-carbon, high-efficiency biochemical system control method and system creatively utilizes big data simulation technology to track and analyze the operating parameters and status of the wastewater biochemical system. It establishes control strategies for the removal of COD (Chemical Oxygen Demand) and nitrogen (ammonia nitrogen, nitrate nitrogen) in relation to biochemical oxygen demand, carbon source dosage, internal recirculation flow, external recirculation flow, and excess sludge discharge. This forms a complete set of control methods and systems for the low-carbon, high-efficiency operation of the biochemical system. This invention aims to achieve precise, low-carbon, high-efficiency control of the biochemical system, enabling on-demand aeration, external carbon source addition, and controlled internal recirculation.

Claims

1. A low-carbon, high-efficiency biochemical system control system, characterized in that: The low-carbon, high-efficiency biochemical system control system is installed in the biochemical reaction tank of the wastewater treatment plant. The biochemical reaction tank includes an inlet end for sequential biochemical treatment of wastewater, an anaerobic tank, an anoxic tank, an aeration tank, a sedimentation tank, and an outlet end. The low-carbon, high-efficiency biochemical system control system includes an internal recirculation control module, a carbon source dosing module, and a precision aeration module. The internal recirculation control module recirculates the nitrate nitrogen requiring denitrification back to the anoxic tank for denitrification. The carbon source dosing module, through online nitrate nitrogen meters installed in the anoxic and aeration tanks, determines the required dosage based on comparisons of dynamic nitrate nitrogen values ​​and trends at the end of the anoxic tank. The precision aeration module adjusts the frequency of the aeration blowers to ensure dissolved oxygen levels are within the appropriate operating range.

2. The low-carbon, high-efficiency biochemical system control system according to claim 1, characterized in that: An online total nitrogen meter, an online ammonia nitrogen meter, an online COD meter, and a biochemical online flow meter Q1 are installed at the inlet end of the biochemical reaction tank. The total nitrogen, ammonia nitrogen, and COD in the influent to the biochemical reactor are monitored online, and the influent flow rate to the biochemical reactor is measured in real time.

3. The low-carbon, high-efficiency biochemical system control system according to claim 1, characterized in that: The anoxic tank is equipped with online ORP, first online dissolved oxygen, and first online nitrate nitrogen meter; The installed online monitoring instruments monitor the ORP, dissolved oxygen, and nitrate nitrogen levels at the end of the anoxic tank in real time.

4. The low-carbon, high-efficiency biochemical system control system according to claim 1, characterized in that: The aeration tank is equipped with a pH meter, a second online nitrate nitrogen meter, an online ammonia nitrogen meter, a sludge concentration meter, a second online dissolved oxygen and temperature sensor. The corresponding instruments monitor and provide feedback on the pH, nitrate nitrogen, ammonia nitrogen, dissolved oxygen, temperature and sludge concentration at the end of the aeration tank in real time.

5. The low-carbon, high-efficiency biochemical system control system according to claim 1, characterized in that: The sedimentation tank is equipped with an online total nitrogen meter, an online ammonia nitrogen meter, and an online COD meter to monitor the total nitrogen, ammonia nitrogen, and COD in the effluent from the biological treatment system online.

6. The low-carbon, high-efficiency biochemical system control system according to claim 1, characterized in that: It also includes an accounting system, which automatically calculates the required air volume and carbon source based on the values ​​of online monitoring instruments, and automatically calculates the nitrification liquor return flow rate based on the influent flow rate, online total nitrogen in the influent, and total nitrogen in the effluent.

7. The low-carbon, high-efficiency biochemical system control system according to claim 1, characterized in that: It also includes a big data simulation analysis and calculation system, which uses the fan air supply, carbon source addition, and internal return flow control as control variables and implements control through a feedback system.

8. The low-carbon, high-efficiency biochemical system control system according to claim 1, characterized in that: The precision aeration module reads the real-time ammonia nitrogen value at the end of the aeration tank, calculates the average value for each cycle, and calculates the difference between the average ammonia nitrogen value of the current cycle and the average ammonia nitrogen value of the previous cycle. The result is ΔNH3-N. Based on the absolute value of ΔNH3-N, |ΔNH3-N|, the range of dissolved oxygen that should be maintained is determined. The frequency of the aeration blower is adjusted to ensure that the dissolved oxygen value is within the range of the required operating range.

9. The low-carbon, high-efficiency biochemical system control system according to claim 1, characterized in that: The internal recirculation control module calculates the corresponding internal recirculation ratio based on the relationship between the influent flow rate, the online total nitrogen in the influent, and the total nitrogen in the effluent. It also calculates the relationship coefficient between the frequency and flow rate of the internal recirculation pump used on site, and outputs the internal recirculation frequency according to the required internal recirculation flow rate to control the internal recirculation flow rate.

10. The low-carbon, high-efficiency biochemical system control system according to claim 1, characterized in that: During the initial startup of the control system, the initial values ​​of DO, carbon source dosage, and internal return flow are assigned based on the analysis of historical data.

Images