Low-carbon high-efficiency biochemical system control method and system

Abstract

The invention provides a low-carbon high-efficiency biochemical system control method and system. The 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, so that the effect of removing total nitrogen is achieved; the carbon source adding module is used for providing 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, so that the carbon source adding amount is accurately controlled; 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] The present invention relates to the field of sewage treatment, and in particular to a low-carbon and high-efficiency biochemical system control method and system. Background Technique

[0002] At present, the biochemical system control of most municipal sewage treatment plants adopts manual control, and experienced operation technicians are required to adjust according to the changes in water quality and water volume. Moreover, most of these adjustments are based on experience and are not refined. At the same time, there is also the situation that the manual response is not timely. In this case, it will cause waste of energy and chemicals and may also cause production accidents. Therefore, automatic intelligent control is the future development trend.

[0003] The mechanism of biological nitrogen removal technology is based on nitrification, denitrification, low DO (dissolved oxygen) nitrification, and simultaneous nitrification and denitrification (SND). Traditional biological nitrogen removal processes have problems such as unstable treatment effects caused by lagging regulation and slow response, large chemical losses and high energy waste caused by extensive management and rough control. Nitrifying bacteria have slow proliferation and it is difficult to maintain a high biological concentration. Especially in winter with low temperatures, the HRT (Hydraulic Retention Time) of the system is long, and a large aeration tank is required, increasing investment and operating costs; in order to maintain a high biological concentration and obtain good denitrification effects, the system must simultaneously carry out sludge and nitrification return liquid, increasing power consumption and operating costs; the system has weak shock resistance, and high-concentration NH 3 -N and NO 2 - wastewater will inhibit the growth of nitrifying bacteria; the acidity generated during nitrification needs to be neutralized with alkali, which not only increases the treatment cost but may also cause secondary pollution, etc.

[0004] Therefore, the key to the operation and management of the biochemical reaction tank lies in the precise control of details. Facing the fluctuations in water quality and water volume, flexibly adjusting the operation strategy, and the control variables include the air supply volume of the blower, the carbon source dosing volume, and the internal return flow rate, which can effectively respond to changes and ensure the effluent water quality. Summary of the Invention

[0005] The present invention provides a low-carbon and high-efficiency biochemical system control method and system, which solves the problem of automatically assigning parameters and automatically controlling the control variables of the biochemical reaction tank (AAO) with the goal of achieving feedback control in the end. The control variables include the air supply volume of the blower, the carbon source dosing volume, and the internal return flow rate, and the technical solutions are as follows:

[0006] A low-carbon and high-efficiency biochemical system control method includes the following steps:

[0007] S1: The control equipment installed in the biochemical reaction tank of the sewage treatment plant is started. The biochemical reaction tank of the sewage treatment plant includes an inlet end, an anaerobic tank, an anoxic tank, an aeration tank, a sedimentation tank, and a drainage end for sequentially performing biochemical treatment on sewage.

[0008] S2: Read the instrument data of the control equipment. The instruments are as follows:

[0009] The following are installed at the inlet end: an online total nitrogen analyzer for influent water, an online ammonia nitrogen analyzer for influent water, an online COD analyzer for influent water, and a biochemical online flowmeter.

[0010] The following are installed at the anoxic tank: an online ORP, a first online dissolved oxygen sensor, and a first online nitrate nitrogen analyzer.

[0011] The following are installed at the aeration tank: a pH meter, a second online nitrate nitrogen analyzer, an online ammonia nitrogen analyzer, a sludge concentration meter, a second online dissolved oxygen sensor, and a temperature sensor.

[0012] The following are installed at the effluent end: an online total nitrogen analyzer, an online ammonia nitrogen analyzer for effluent water, and an online COD analyzer for effluent water.

[0013] S3: Judge the online ammonia nitrogen value in the aeration tank and adjust the frequency of the aeration fan through the precise aeration module.

[0014] S4: Calculate the internal reflux flow rate according to the biochemical influent flow rate, the online total nitrogen in the influent water, and the total nitrogen requirement of the effluent water, and adjust the internal reflux frequency through the internal reflux control module.

[0015] S5: Adjust the carbon source dosage according to the value of the first online nitrate nitrogen analyzer in the anoxic tank through the carbon source dosing module.

[0016] S6: Maintain the operating state.

[0017] Further, the precise aeration module adjusts the frequency of the aeration fan, including the following steps:

[0018] S11: Start the control equipment.

[0019] S12: Read the instrument data, including the online ammonia nitrogen analyzer and the second online dissolved oxygen in the aeration tank.

[0020] S13: Judge the size of the monitored value of the online ammonia nitrogen analyzer. When it exceeds the set upper limit, the system alarms. When it does not exceed the upper limit value, step S14 is executed; the upper limit value is determined according to the required effluent index.

[0021] S14: Periodically compare the magnitude of |ΔNH 3 -N| to adjust the operating range of DO. All parameter values can be adjusted and an adjustment interface is reserved.

[0022] S15: Maintain the operating state.

[0023] Further, in step S14, the specific logic is as follows:

[0024] S141: Ensure that a ≤ DO, and the operating range of DO is a ≤ DO ≤ b, b < DO ≤ c, c < DO ≤ d. Initially, it is set as b < DO ≤ c;

[0025] S142: If |ΔNH 3 -N| < A, then maintain the operation of b < DO ≤ c;

[0026] S143: If ΔNH 3 -N ≥ A or ΔNH 3 -N > 0.1 for three consecutive cycles, then adjust DO to the next operating range until the operating range of DO ≤ 5. When DO > 5 mg / L, the system alarms and it is recommended to reduce the influent flow rate;

[0027] S144: When ΔNH 3 -N ≤ -A or ΔNH 3 -N < -0.1 for three consecutive cycles, adjust DO to the previous operating range until a ≤ DO ≤ b;

[0028] The value range description of the parameters in the above steps:

[0029] (1) The operating range and control limit of DO are adjusted according to the actual later operation. The values of a, b, c, and d are gradually determined according to the reaction mechanism of the biochemical reaction tank and the actual situation, and the values are 0.5 mg / L, 1 mg / L, 1.5 mg / L, and 2 mg / L in sequence; After DO exceeds 2 mg / L, each 0.5 mg / L is an operating range; The upper limit value of DO is controlled by ORP in the anoxic section without destroying the anoxic condition in the anoxic section. If there is no ORP in the anoxic section, set the upper limit value of DO not exceeding 5 mg / L;

[0030] (2) ΔNH 3 -N represents the difference between the average value of NH 3 -N within 1 hour and the average value of NH 3 -N in the previous cycle. The value of A is 0.3 mg / L, and one cycle is 1 hour.

[0031] Further, in step S4, the control logic of the carbon source dosing module is as follows:

[0032] S21: Start the control device;

[0033] S22: Read the instrument data, including the biochemical on-line flowmeter at the influent end and the first on-line nitrate nitrogen analyzer in the anoxic tank;

[0034] S23: Periodically judge the value of the first on-line nitrate nitrogen analyzer, and calculate the carbon source dosing amount according to the value of the first on-line nitrate nitrogen analyzer and the biochemical influent flow rate,

[0035] All parameter values need to be adjustable, and adjustment interfaces should be reserved.

[0036] S24: Maintain the running state.

[0037] Furthermore, in step S23, the specific logic is as follows:

[0038] S231. When B < the first on-line nitrate nitrogen analyzer < Z, maintain the original dosing. When the first on-line nitrate nitrogen analyzer > Z, increase the carbon source dosing amount by {η*(the value of the first on-line nitrate nitrogen analyzer - Z) / Z}, observe for one cycle. If the value of the first on-line nitrate nitrogen analyzer returns to B < the first on-line nitrate nitrogen analyzer < Z, maintain the operation. If the first on-line nitrate nitrogen analyzer is still greater than Z, continue to increase the carbon source dosing amount until the value of the first on-line nitrate nitrogen analyzer returns to B < the first on-line nitrate nitrogen analyzer < Z. η is an adjustable coefficient, and one cycle is 2 hours; Z is the recommended control value of the first on-line nitrate nitrogen analyzer, and B is the minimum value of the first on-line nitrate nitrogen analyzer.

[0039] S232. When the first on-line nitrate nitrogen analyzer < B, adjust and reduce the carbon source dosing amount by { *(the value of the first on-line nitrate nitrogen analyzer - Z) / Z}, observe for one cycle. If the value of the first on-line nitrate nitrogen analyzer returns to B < the first on-line nitrate nitrogen analyzer < Z, maintain the operation. If the first on-line nitrate nitrogen analyzer is still less than B, continue to reduce the carbon source dosing amount until the value of the first on-line nitrate nitrogen analyzer returns to B < the first on-line nitrate nitrogen analyzer < Z. is an adjustable coefficient, and one cycle is 2 hours; Z is the recommended control value of the first on-line nitrate nitrogen analyzer, and B is the minimum value of the first on-line nitrate nitrogen analyzer.

[0040] S233. When the first on-line nitrate nitrogen analyzer is greater than the first set value, the system alarms and reduces the water inlet flow rate. The first set value is adjusted according to the actual effluent standard.

[0041] Furthermore, in step S5, the carbon source dosing amount is adjusted through the carbon source dosing module, including the following steps:

[0042] S31: Control the equipment to start.

[0043] S32: Read the instrument data, including the inlet online total nitrogen analyzer and the biochemical online flowmeter at the water inlet end.

[0044] S33: Periodically calculate the internal reflux flow rate according to the value of the inlet online total nitrogen analyzer, the biochemical inlet flow rate, and the total nitrogen requirement of the effluent. The specific logic is as follows:

[0045] S331: Set the initial internal reflux pump frequency according to the initial internal reflux ratio, and set the carbon source dosing flow rate according to the initial first on-line nitrate nitrogen analyzer.

[0046] S332. The internal reflux frequency is adjusted according to the total nitrogen TN in the influent water and the online nitrate nitrogen 2TNe, once per cycle. The adjustment relationship is: internal reflux pump frequency = ε * β * Q1 * (TN - TNe) / TNe, where ε is an adjustable coefficient, β is the relationship coefficient between the internal reflux pump frequency and the internal reflux pump flow rate; Q1 is the biochemical online flow rate; one cycle is 8 hours.

[0047] S33: Maintain the operating state.

[0048] A low-carbon and high-efficiency biochemical system control system includes an internal reflux control module, a carbon source dosing module, and a precise aeration module.

[0049] The internal reflux control module returns the nitrate nitrogen that needs to be denitrified to the anoxic tank for denitrification to achieve the effect of removing total nitrogen. According to the magnitude relationship of the influent flow rate, the total nitrogen in the influent water, and the total nitrogen in the effluent water, the corresponding internal reflux ratio is calculated, and the relationship coefficient between the frequency and the flow rate is calculated based on the internal reflux pump used on-site. The internal reflux frequency is output according to the required internal reflux flow rate to control the internal reflux flow rate.

[0050] The carbon source dosing module uses the online nitrate nitrogen analyzers installed in the anoxic tank and the aeration tank to give the current required drug dosage based on the comparison of the dynamic nitrate nitrogen value at the end of the anoxic tank and the comparison of the change trend, so as to achieve precise control of the carbon source dosing amount.

[0051] The precise aeration module reads the real-time ammonia nitrogen value at the end of the aeration tank, calculates the average value of the values per cycle, calculates the difference between the ammonia nitrogen average value of this cycle and the ammonia nitrogen average value of the previous cycle, and the calculation result is ΔNH 3 -N. According to the absolute value |ΔNH 3 -N|, the operating range of the dissolved oxygen is judged, and the dissolved oxygen value is made to operate within the operating range by adjusting the frequency of the aeration fan. 3

[0052] Furthermore, it also includes an accounting system and a big data simulation analysis and calculation system.

[0053] The accounting system is used to automatically calculate the required air volume and carbon source amount according to the values of the online monitoring instruments, and automatically calculate the nitrification liquid return flow rate according to the influent flow rate, the total nitrogen in the influent water, and the total nitrogen in the effluent water.

[0054] The big data simulation analysis and calculation system uses the air supply of the fan, the carbon source dosing amount, and the internal return flow control as control variables, and implements control through the feedback system.

[0055] Furthermore, an in-line total nitrogen analyzer for influent water, an in-line ammonia nitrogen analyzer for influent water, an in-line COD analyzer for influent water, and a biochemical in-line flowmeter Q1 are provided at the influent end of the biochemical reaction tank; the total nitrogen, ammonia nitrogen, and COD in the influent water of the biochemical reaction tank are monitored online, and the influent volume of the biochemical reaction tank is measured in real time;

[0056] An online ORP, a first online dissolved oxygen analyzer, and a first online nitrate nitrogen analyzer are provided in the anoxic tank; the online monitoring instruments provided monitor the ORP in the anoxic tank, the dissolved oxygen at the end of the anoxic tank, and the nitrate nitrogen value in real time;

[0057] A pH meter, a second online nitrate nitrogen analyzer, an online ammonia nitrogen analyzer, a sludge concentration meter, a second online dissolved oxygen analyzer, and a temperature sensor are provided in the aeration tank; the corresponding instruments monitor and feedback the pH, nitrate nitrogen, ammonia nitrogen, dissolved oxygen, temperature at the end of the aeration tank, and the sludge concentration in the aeration tank in real time;

[0058] An in-line total nitrogen analyzer for effluent water, an in-line ammonia nitrogen analyzer for effluent water, and an in-line COD analyzer for effluent water are provided in the sedimentation tank. The total nitrogen, ammonia nitrogen, and COD in the effluent of the biochemical system are monitored online.

[0059] Furthermore, at the initial stage of starting the control system, the initial assignments of DO, carbon source dosage, and internal reflux flow rate are completed according to the analyzed historical data values.

[0060] The low-carbon and high-efficiency biochemical system control method and system creatively utilize big data simulation technology to track and analyze the operating parameters and operating status of the sewage biochemical system, respectively establish control strategies between the removal of "COD (Chemical Oxygen Demand) and nitrogen (ammonia nitrogen, nitrate nitrogen)" and biochemical oxygen demand, carbon source dosage, internal reflux flow rate, external reflux flow rate, and excess sludge discharge amount, and form a complete set of control methods and systems for the low-carbon and high-efficiency operation of the biochemical system. The purpose of the present invention is to achieve the low-carbon, high-efficiency, and precise control of the biochemical system, realize on-demand aeration, add external carbon source, and control internal reflux.

[0061] The present invention has the following beneficial effects:

[0062] (1) In the low-carbon biochemical system control method of the present invention, the formation of aerobic and anoxic microenvironments in microbial flocs is closely related to the dissolved oxygen concentration. The average dissolved oxygen in the aerobic tank is controlled at 1 - 1.5 mg / L, which is only about 50% of the theoretical value of the dissolved oxygen (2 mg / L) in the traditional activated sludge process.

[0063] (2) For the carbon source addition of the present invention, according to the size of the feedback value, the front-end carbon source addition ratio is adjusted in a timely manner to achieve the effect of on-demand addition and carbon source saving.

[0064] (3) The present invention controls the frequency of the internal reflux pump by outputting it periodically according to the calculation results. Before the system was used, the internal reflux in the sewage treatment plant adopted all fixed-frequency reflux, with the set frequency being 40 Hz. After the system was put into operation, the frequencies of the two internal reflux pumps corresponding to a single series would operate between 20 and 40 Hz according to the influent flow rate (Q1), the influent online total nitrogen (TN), and the effluent total nitrogen (TNe). The average operating frequency was 30 Hz, and the effluent total nitrogen reached the standard stably, with the power consumption saved by about 25%.

[0065] (4) The present invention can self-learn and optimize the operation, greatly reducing the operating energy consumption and chemical consumption, significantly improving the operation and management level, and achieving the goal of improving the quality and efficiency of sewage treatment operation with reliable operation, low carbon, high efficiency, power saving, and chemical saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a schematic structural diagram of the control system of the low-carbon and high-efficiency biochemical system;

[0067] Figure 2 is a working flowchart of the control method of the low-carbon and high-efficiency biochemical system;

[0068] Figure 3 is a schematic diagram of the precise aeration adjustment process;

[0069] Figure 4 is a schematic diagram of the carbon source dosing process;

[0070] Figure 5 is a graph showing the change trends of ammonia nitrogen and dissolved oxygen in a certain series of biochemical ditches. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] As Figure 1 shown, the control system of the low-carbon and high-efficiency biochemical system is installed in the biochemical reaction tank part of the sewage treatment plant. The biochemical reaction tank of the sewage treatment plant includes an influent end, an anaerobic tank, an anoxic tank, an aeration tank, a sedimentation tank, and a drainage end for sequentially performing biochemical treatment on sewage; the control system of the low-carbon and high-efficiency biochemical system includes:

[0072] An internal reflux control module calculates the corresponding internal reflux ratio according to the magnitude relationship of the influent flow rate, the influent online total nitrogen, and the effluent total nitrogen values, calculates the relationship coefficient between the frequency and the flow rate according to the internal reflux pump used on site, and outputs the internal reflux frequency according to the required internal reflux flow rate to control the internal reflux flow rate.

[0073] Carbon source dosing module. The total nitrogen in the effluent of the biochemical reaction tank is mainly composed of nitrate nitrogen (nitrate). Controlling the nitrate nitrogen in the effluent of the biochemical reaction tank can effectively ensure the total nitrogen in the effluent. The change of the carbon source dosing amount and the amount of internal reflux directly affect the nitrate nitrogen in the effluent. In the process control, on-line nitrate nitrogen analyzers are respectively set in the anoxic tank and the aeration tank. According to the comparison of the dynamic nitrate nitrogen values and the change trend comparison in the anoxic tank and the aeration tank, the program gives the adjustment of the internal reflux amount and the current required drug dosage to achieve precise control of the carbon source dosing amount.

[0074] Precision aeration module, which is connected to the aeration tank through the fan adjustment module; effectively solves the oxidation-reduction relationship in the process of sewage treatment microorganisms removing COD, ammonia nitrogen, and TN, and realizes the organic balance of oxidation-reduction. The precision aeration module is used to measure the aeration of the biochemical reaction tank, and the aeration intensity is controlled according to the ammonia nitrogen treatment situation. Generally, it can meet the requirements of COD removal and ammonia nitrogen removal at the same time, and also take into account the removal of part of TP (total phosphorus). The control of the aeration module in this project operates with the treatment of ammonia nitrogen as the indicator. There is a positive relationship between ammonia nitrogen and the level of dissolved oxygen, and a negative relationship between nitrate nitrogen and the level of dissolved oxygen. Therefore, an on-line ammonia nitrogen analyzer is added to the aeration tank. The process control program can timely detect the change trend of ammonia nitrogen according to the on-line feedback signal of ammonia nitrogen, automatically judge by the program to adjust the dissolved oxygen tracking interval range and the corresponding target value, and real-time adjust the air volume variable value of the aeration fan. The dissolved oxygen is set between 0.5 and 5 (the upper limit is controlled according to the ORP at the end of the anoxic tank to avoid destroying the anoxic environment) mg / L, ensuring that COD, ammonia nitrogen, and nitrate nitrogen all meet the standards continuously and have a safety margin at a relatively low dissolved oxygen level.

[0075] Recording and analysis system, on-line monitoring instruments are set at the inlet end, anoxic tank, aeration tank, and sedimentation tank for data collection;

[0076] At the inlet end of the biochemical reaction tank, an on-line total nitrogen analyzer for inlet water, an on-line ammonia nitrogen analyzer for inlet water, an on-line COD analyzer for inlet water, and a biochemical on-line flowmeter Q1 are set; on-line monitoring of the total nitrogen, ammonia nitrogen, and COD in the influent of the biochemical reaction tank, and real-time measurement of the influent volume of the biochemical reaction tank. The monitored and measured data serve as the control basic data for the low-carbon and high-efficiency biochemical system control system;

[0077] In the anoxic tank, an on-line ORP, a first on-line dissolved oxygen, and a first on-line nitrate nitrogen analyzer are set; the on-line monitoring instruments set monitor the ORP in the anoxic tank, the dissolved oxygen at the end of the anoxic tank, and the nitrate nitrogen value in real time, and the real-time values serve as the control basic data for the low-carbon and high-efficiency biochemical system control system;

[0078] A pH meter, a second on-line nitrate nitrogen analyzer, an on-line ammonia nitrogen analyzer, a sludge concentration meter, a second on-line dissolved oxygen meter and a temperature sensor are installed in the aeration tank. The corresponding instruments monitor and feedback the pH, nitrate nitrogen, ammonia nitrogen, dissolved oxygen, temperature at the end of the aeration tank and the sludge concentration in the aeration tank in real time, and the real-time values serve as the control basic data for the low-carbon and high-efficiency biochemical system control system.

[0079] An on-line total nitrogen analyzer for effluent, an on-line ammonia nitrogen analyzer for effluent and an on-line COD analyzer for effluent are installed in the sedimentation tank. The total nitrogen, ammonia nitrogen and COD in the effluent of the biochemical system are monitored on-line, and the measured data serve as the control basic data for the low-carbon and high-efficiency biochemical system control system.

[0080] The accounting system, based on nitrification, denitrification, low-DO nitrification, simultaneous nitrification and denitrification (SND), achieves the intelligent operation goal of automatic quantification and automatic adjustment of the operating parameters of the biochemical reaction tank. Among them, the automatic design and calculation of the calculation parameters of the biochemical reaction tank are based on, for example, automatically calculating the required air volume and carbon source amount according to the values of the on-line monitoring instruments, and automatically calculating the nitrified liquid return flow according to data such as the influent flow rate, influent on-line total nitrogen and effluent total nitrogen values.

[0081] The big data simulation analysis and calculation system, based on the activated sludge series models of COD and nitrogen removal theories such as nitrification and denitrification, simultaneous nitrification and denitrification; with the blower air supply volume, carbon source dosage, internal return flow control as control variables, and implements control through the feedback system.

[0082] This system relies on the existing biochemical reaction tank (AAO) of the sewage treatment plant as the basis, and realizes automatic intelligent control through the values of the on-line COD of the influent, on-line total nitrogen of the influent, on-line ammonia nitrogen of the influent, influent flow rate, ORP of 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, on-line COD of the effluent, on-line total nitrogen of the effluent, on-line ammonia nitrogen of the effluent monitoring instruments; at the initial stage of system startup, the initial assignments of DO, carbon source dosage and internal return flow are completed according to the analysis of historical data values, and during operation, the key effluent indicators are used as the control boundaries and are continuously adjusted automatically.

[0083] As Figure 2 shown, the control method of the low-carbon and high-efficiency biochemical system includes the following steps:

[0084] S1: Equipment startup;

[0085] S2: Read instrument data, including:

[0086] Inlet end: On-line total nitrogen analyzer for influent, on-line ammonia nitrogen analyzer for influent, on-line COD analyzer for influent, biochemical on-line flowmeter;

[0087] Anoxic tank: On-line ORP, first on-line dissolved oxygen meter, first on-line nitrate nitrogen analyzer;

[0088] Aeration tank: pH meter, second on-line nitrate nitrogen analyzer, on-line ammonia nitrogen analyzer, sludge concentration meter, second on-line dissolved oxygen sensor and temperature sensor;

[0089] Outlet end: on-line total nitrogen analyzer, outlet on-line ammonia nitrogen analyzer and outlet on-line COD analyzer.

[0090] S3: Interpret the on-line ammonia nitrogen value in the aeration tank and adjust the frequency of the aeration fan;

[0091] S4: Calculate the internal reflux flow rate according to the biochemical influent flow rate, influent on-line total nitrogen and outlet total nitrogen requirements, and adjust the internal reflux frequency;

[0092] S5: Adjust the carbon source dosage according to the value of the first on-line nitrate nitrogen analyzer in the anoxic tank;

[0093] S6: Maintain the operating state.

[0094] As Figure 3 shown, the aeration logic of the precise aeration module is as follows:

[0095] This system requires the corresponding instruments of the original biochemical reaction tank (AAO). The required instruments include the on-line ammonia nitrogen analyzer at the end of the aeration tank, the second on-line dissolved oxygen sensor at the end of the aeration tank, and the on-line ORP in the anoxic tank; read the real-time value of ammonia nitrogen (NH 3 -N) at the end of the aeration tank, calculate the average value of the values in each cycle, calculate the difference between the ammonia nitrogen average value of this cycle and the ammonia nitrogen average value of the previous cycle, and the calculation result is ΔNH 3 -N. According to the absolute value |ΔNH 3 -N| of ΔNH 3 -N, judge the operating range of dissolved oxygen (DO), and adjust the frequency of the aeration fan to achieve the effect that the dissolved oxygen value operates in the operating range, so as to achieve on-demand aeration and save power consumption.

[0096] The specific control logic is as follows:

[0097] S11: Equipment startup;

[0098] S12: Read the instrument data, including

[0099] Aeration tank: on-line ammonia nitrogen analyzer, second on-line dissolved oxygen;

[0100] S13: Judge the size of the monitoring value of the on-line ammonia nitrogen analyzer. When it exceeds the set upper limit, the system alarms. When it does not exceed the upper limit value, the next step is executed; the upper limit value is determined according to the required effluent index;

[0101] S14: Periodically compare the size of |ΔNH 3 -N|, so as to adjust the operating range of DO. The specific logic is as follows:

[0102] S141. Ensure that a ≤ DO, and the operating range of DO is a ≤ DO ≤ b, b < DO ≤ c, c < DO ≤ d. Initially, set b < DO ≤ c;

[0103] S142. If |ΔNH 3 -N| < A, then maintain the operation of b < DO ≤ c;

[0104] S143. If ΔNH 3 -N ≥ A or ΔNH 3 -N > 0.1 for three consecutive cycles, then adjust DO to the next operating range until the operating range of DO ≤ 5. When DO > 5 mg / L, the system alarms and it is recommended to reduce the influent flow rate;

[0105] S144. When ΔNH 3 -N ≤ -A or ΔNH 3 -N < -0.1 for three consecutive cycles, adjust DO to the previous operating range until a ≤ DO ≤ b.

[0106] Explanation of parameter value settings:

[0107] (1) The operating range and control limit of DO can be adjusted according to the actual operation in the later stage. In this scheme, the values of a, b, c, and d are 0.5 mg / L, 1 mg / L, 1.5 mg / L, and 2 mg / L respectively (which can be gradually determined according to the reaction mechanism of the biochemical reaction tank and the actual situation); after DO exceeds 2 mg / L, each 0.5 mg / L is an operating range; the upper limit value of DO is controlled by ORP in the anoxic section, based on not destroying the anoxic condition in the anoxic section; if there is no ORP in the anoxic section, set the upper limit value of DO not exceeding 5 mg / L;

[0108] (2) ΔNH 3 -N represents the difference between the average value of NH 3 -N within 1 hour and the average value of NH 3 -N in the previous cycle. In this scheme, the value of A is 0.3 mg / L. One cycle is 1 hour.

[0109] All parameter values need to be adjustable, and adjustment interfaces are reserved.

[0110] S15: Maintain the operating state.

[0111] As Figure 4 shown, the dosing logic of the carbon source dosing module is as follows:

[0112] Carbon source dosing module. The total nitrogen in the effluent of the biochemical reaction tank is mainly composed of nitrate nitrogen. Controlling the nitrate nitrogen in the effluent of the biochemical reaction tank can effectively ensure the total nitrogen in the effluent. The amount of carbon source dosing directly affects the nitrate nitrogen in the effluent. In the process control, according to the comparison of the dynamic nitrate nitrogen value at the end of the anoxic tank and the change trend comparison, the system then gives the current required dosage of medicine to achieve precise control of the carbon source dosing amount. The initial carbon source dosing amount and the internal reflux flow are designed and started by the debugging personnel according to the influent carbon-nitrogen ratio, and are adjusted according to the actual water quality changes after startup.

[0113] This system requires the corresponding instruments of the original biochemical reaction tank (AAO). The required instrument is the nitrate nitrogen at the end of the anoxic tank; read the real-time value of the nitrate nitrogen at the end of the anoxic tank: the first on-line nitrate nitrogen analyzer. According to the size of the first on-line nitrate nitrogen analyzer, judge the change ratio of the required carbon source to be dosed, and output the carbon source dosing value to achieve the effect of precise carbon source dosing.

[0114] Control logic:

[0115] S21: Equipment startup;

[0116] S22: Read instrument data, including

[0117] Inlet end: Biochemical on-line flowmeter;

[0118] Anoxic tank: The first on-line nitrate nitrogen analyzer;

[0119] S23: Periodically judge the size of the value of the first on-line nitrate nitrogen analyzer, and calculate the carbon source dosing amount according to the size of the value of the first on-line nitrate nitrogen analyzer and the biochemical influent flow. The specific logic is as follows:

[0120] S231. When B < the first on-line nitrate nitrogen analyzer < Z, maintain the original dosing. When the first on-line nitrate nitrogen analyzer > Z, increase the carbon source dosing amount by {η*(the value of the first on-line nitrate nitrogen analyzer - Z) / Z}, observe for one cycle. If the value of the first on-line nitrate nitrogen analyzer returns to B < the first on-line nitrate nitrogen analyzer < Z, then maintain the operation. If the first on-line nitrate nitrogen analyzer is still greater than Z, continue to increase the carbon source dosing amount until the value of the first on-line nitrate nitrogen analyzer returns to B < the first on-line nitrate nitrogen analyzer < Z. η is an adjustable coefficient, and in this scheme, η is taken as 0.2; one cycle is 2 hours;

[0121] S232. When the first on-line nitrate nitrogen analyzer < B, adjust and reduce the carbon source dosing amount by { *(the value of the first on-line nitrate nitrogen analyzer - Z) / Z}, observe for one cycle. If the value of the first on-line nitrate nitrogen analyzer returns to B < the first on-line nitrate nitrogen analyzer < Z, then maintain the operation. If the first on-line nitrate nitrogen analyzer is still less than B, continue to reduce the carbon source dosing amount until the value of the first on-line nitrate nitrogen analyzer returns to B < the first on-line nitrate nitrogen analyzer < Z, is an adjustable coefficient, and in this scheme, it is taken as 0.2; one cycle is 2 hours;

[0122] S233. When the first online nitrate nitrogen analyzer is greater than 5 mg / L (this value can be adjusted according to the actual effluent standard), the system alarms, and it is recommended to reduce the influent flow rate.

[0123] Description of parameter value selection:

[0124] (1) Z is the recommended control value of the first online nitrate nitrogen analyzer. In this scheme, it is taken as 2 mg / L (this value can be adjusted according to the actual effluent standard);

[0125] (2) B is the minimum value of the first online nitrate nitrogen analyzer. In this scheme, it is taken as 1 mg / L (this value can be adjusted according to the actual effluent standard).

[0126] All parameter values need to be adjustable, and adjustment interfaces are reserved.

[0127] S24: Maintain the operating state.

[0128] In the internal reflux control module, the internal reflux, as the way of digestive fluid reflux, mainly functions to reflux the nitrate nitrogen that needs to be denitrified to the anoxic tank for denitrification, and finally achieve the effect of removing total nitrogen. This system will control the internal reflux flow rate according to the magnitude relationship of the influent flow rate (Q1), the influent online total nitrogen (TN), and the effluent total nitrogen (TNe) values.

[0129] Control logic:

[0130] S31: Equipment startup;

[0131] S32: Read instrument data, including

[0132] Inlet end: Influent online total nitrogen analyzer, biochemical online flowmeter;

[0133] S33: Periodically calculate the internal reflux flow rate according to the influent online total nitrogen analyzer value, the biochemical influent flow rate, and the effluent total nitrogen requirement. The specific logic is as follows:

[0134] S331: Set the initial internal reflux pump frequency according to the initial internal reflux ratio, and set the carbon source dosing flow rate according to the initial first online nitrate nitrogen analyzer;

[0135] S332: Adjust the internal reflux frequency according to the influent online total nitrogen TN and the online nitrate nitrogen 2TNe. It is adjusted once per cycle, and the adjustment relationship is internal reflux pump frequency = ε * β * Q1 * (TN - TNe) / TNe, where ε is an adjustable coefficient, and β is the internal reflux pump frequency and internal reflux pump flow coefficient; one cycle is 8 hours.

[0136] S33: Maintain the operating state.

[0137] In the embodiment, the specific implementation manner of the present invention will be further described below in combination with the embodiment.

[0138] The designed total treatment capacity of a sewage treatment plant is 100,000 m 3 / d. The biochemical ditch part is divided into 4 series, and one of the series is taken as a pilot. The designed scale of this series of biochemical ditch is 25,000 m 3 / d. The actual influent water quality and the implemented effluent water quality indexes of the project are shown in Table 1.

[0139] Table 1 Actual influent water quality and implemented effluent water quality indexes of a sewage treatment project:

[0140]

[0141] According to the requirements of the control system, it is necessary to equip on-line monitoring instruments such as on-line COD of influent water, on-line total nitrogen of influent water, on-line ammonia nitrogen of influent water, influent water flow, ORP of anoxic tank, nitrate nitrogen at the end of anoxic tank, dissolved oxygen (temperature) at the end of aeration tank, ammonia nitrogen at the end of aeration tank, nitrate nitrogen at the end of aeration tank, on-line COD of effluent water, on-line total nitrogen of effluent water, on-line ammonia nitrogen of effluent water, etc., and connect to the frequency control interface of aeration blower (aeration electric valve), control of carbon source dosing pump, and frequency control interface of internal reflux pump.

[0142] Precision aeration module:

[0143] It is necessary to read the on-line ammonia nitrogen analyzer and the real-time value of the second on-line dissolved oxygen in the aeration tank;

[0144] The specific control process is as follows:

[0145] The water plant has a corresponding blower for this biochemical ditch and an electric valve (regulating type) is installed on the main aeration pipeline. The control is carried out from two aspects. The required dissolved oxygen can be controlled by the frequency of the blower, or the dissolved oxygen can be controlled by the opening of the electric valve (regulating type).

[0146] During the initial commissioning, the operating conditions of the water plant are taken as the starting point. After putting into operation, calculations are carried out through the real-time value of ammonia nitrogen (NH 3 -N) at the end of the aeration tank read. The average value of each cycle is calculated, and then the difference between the average value of ammonia nitrogen in this cycle and the average value of ammonia nitrogen in the previous cycle is calculated. According to the size of the difference, the operating interval range of dissolved oxygen (DO) is judged. The frequency of the aeration blower is adjusted or the electric valve (regulating type) is used to achieve the effect that the dissolved oxygen value operates within the operating interval. When the dissolved oxygen needs to be increased, the frequency of the blower is increased or the opening of the electric valve (regulating type) is enlarged. When the dissolved oxygen needs to be decreased, the frequency of the blower is decreased or the opening of the electric valve (regulating type) is reduced. Through on-site commissioning, the dissolved oxygen can reach the required operating interval within basically 30 minutes, and the ammonia nitrogen in the effluent always meets the effluent standard requirements.

[0147] The change trend chart of ammonia nitrogen and dissolved oxygen can be seen in the appendix Figure 5During the process where the ammonia nitrogen value at the end of the aeration tank increased from 0.04 mg / L to 0.14 mg / L and then to 0.19 mg / L, the system automatically judged the change value of ammonia nitrogen and timely 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 adjustment of the dissolved oxygen operating range, the ammonia nitrogen value gradually decreased, and then the dissolved oxygen operating range also gradually decreased, not only saving the operating power consumption but also avoiding the situation of excessive ammonia nitrogen in the effluent.

[0148] The carbon source dosing module needs to read the biochemical on-line flowmeter at the inlet end and the first on-line nitrate nitrogen analyzer in the anoxic tank; the specific control process is as follows:

[0149] This system controls the front-end carbon source dosing in real time according to the reading of the first on-line nitrate nitrogen analyzer at the end of the anoxic tank. In this system, the lowest value and the recommended control value are set for the first on-line nitrate nitrogen analyzer. The values are given based on the original operating experience of the water plant combined with the process principle. When the real-time value is between the lowest value and the recommended control value, the original dosing is maintained. When the real-time value is less than the lowest value, the carbon source dosing amount is reduced proportionally. When the real-time value is greater than the recommended control value, the carbon source dosing amount is increased proportionally; during the initial commissioning, the operating conditions of the water plant are used as the starting point, and the system automatically completes the control of carbon source dosing according to the change of the real-time value, achieving the effect of dosing carbon source on demand.

[0150] The internal reflux module needs to read the inlet on-line total nitrogen analyzer and the biochemical on-line flowmeter at the inlet end; the specific control process is as follows:

[0151] Calculate the corresponding internal reflux ratio according to the size relationship of the biochemical influent flow rate (Q1), the inlet on-line total nitrogen (TN), and the effluent total nitrogen (TNe) values, and calculate the relationship coefficient between the frequency and the flow rate according to the internal reflux pump used on site. Output the internal reflux frequency according to the required internal reflux flow rate to control the internal reflux flow rate; the design capacity of the sewage treatment plant is 100,000 m 3 / d. Before using this system, the internal reflux adopted all fixed-frequency reflux, and the set frequency was 40 Hz. After this system was put into operation, the frequencies of the 2 internal reflux pumps corresponding to a single series would operate between 20 - 40 Hz according to the different values of the influent flow rate (Q1), the inlet on-line total nitrogen (TN), and the effluent total nitrogen (TNe). The average operating frequency was 30 Hz, and the effluent total nitrogen index did not exceed the standard. While meeting the denitrification requirements, the power consumption was saved.

[0152] For the low-carbon and high-efficiency biochemical control system, the accuracy of the instruments is the basis for the implementation of the system. The overall control system needs to operate according to the real-time feedback of the corresponding instruments. Therefore, after the system is implemented, attention should also 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 finally achieve the low-carbon and high-efficiency control of the biochemical system.

[0153] The low-carbon and high-efficiency biochemical system control method and system creatively utilize big data simulation technology to track and analyze the operating parameters and states of the sewage biochemical system, establish control strategies between the removal of "COD (Chemical Oxygen Demand) and nitrogen (ammonia nitrogen, nitrate nitrogen)" and biochemical oxygen demand, carbon source dosage, internal reflux flow rate, external reflux flow rate, and excess sludge discharge amount respectively, and form a complete set of control methods and systems for the low-carbon and high-efficiency operation of the biochemical system. The purpose of the present invention is to achieve the low-carbon, high-efficiency and precise control of the biochemical system, realize on-demand aeration, add external carbon source, and control internal reflux.

Claims

1. A low-carbon and high-efficiency biochemical system control method, comprising the following steps: S1: The control equipment installed in the biochemical reaction tank of the sewage treatment plant is started. The biochemical reaction tank of the sewage treatment plant includes the water inlet end, anaerobic tank, anoxic tank, aeration tank, sedimentation tank and discharge end for biochemical treatment of sewage in sequence; S2: Read the instrument data of the control device, the instrument is as follows: The water inlet end is equipped with: an inlet water online total nitrogen meter, an inlet water online ammonia nitrogen meter, an inlet water online COD meter, and a biochemical online flow meter; The anoxic tank is equipped with: online ORP, first online dissolved oxygen, first online nitric nitrogen meter; The aeration tank is equipped with: a pH meter, a second online nitric nitrogen meter, an online ammonia nitrogen meter, a sludge concentration meter, a second online dissolved oxygen sensor and a temperature sensor; The outlet end is equipped with: an online total nitrogen meter, an outlet water online ammonia nitrogen meter and an outlet water online COD meter; S3: Determine the online ammonia nitrogen value of the aeration tank and adjust the aeration fan frequency through the precise aeration module; S4: According to the biochemical inlet flow rate, inlet online total nitrogen and outlet total nitrogen requirements, the internal reflux flow rate is calculated through the internal reflux control module, and the internal reflux frequency is adjusted; S5: According to the value of the first online nitric nitrogen meter in the anoxic tank, the carbon source dosage is adjusted through the carbon source dosage module; S6: Keep running.

2. The low-carbon and high-efficiency biochemical system control method according to claim 1, characterized in that: In step S3, the precise aeration module adjusts the aeration fan frequency, including the following steps: S11: Control device startup; S12: Read instrument data, including the online ammonia nitrogen meter and the second online dissolved oxygen meter of the aeration tank; S13: Determine the value monitored by the online ammonia nitrogen meter. If the value exceeds the set upper limit, the system alarms. If the value does not exceed the upper limit, run step S14. The upper limit is determined according to the required water output index. S14: Periodically compare the size of |ΔNH3-N| to adjust the operating range of DO. All parameter values ​​are adjustable and an adjustment interface is reserved. S15: Keep running.

3. The low-carbon and high-efficiency biochemical system control method according to claim 2 is characterized in that: In step S14, the specific logic is as follows: S141: Ensure that a≤DO, the DO operation range is a≤DO≤b, b<DO≤c, c<DO≤d, and the initial setting is b<DO≤c; S142: If |ΔNH3-N|<A, keep b<DO≤c; S143: If ΔNH3-N≥A or ΔNH3-N>0.1 for three consecutive cycles, adjust DO to the next operating range until DO≤5 operating range. When DO>5mg / L, the system alarms and it is recommended to reduce the water intake. S144: When ΔNH3-N≤-A or ΔNH3-N<-0.1 for three consecutive cycles, adjust DO to the previous operation range until a≤DO≤b; Description of parameter values ​​for the above steps: (1) The DO operating range and control limit are adjusted according to the actual operation in the later stage. The a, b, c, and d are gradually determined according to the reaction mechanism of the biochemical reaction tank and the actual situation, and the values ​​are 0.5 mg / L, 1 mg / L, 1.5 mg / L, and 2 mg / L respectively; after DO exceeds 2 mg / L, each 0.5 mg / L is an operating range; the DO upper limit is controlled by the ORP of the anoxic section, and the anoxic conditions of the anoxic section are not destroyed. If there is no ORP in the anoxic section, the DO upper limit is set to no more than 5 mg / L; (2) ΔNH3-N represents the difference between the average NH3-N value within one hour and the average NH3-N value in the previous cycle. A is taken as 0.3 mg / L, and one cycle is 1 hour.

4. The low-carbon and high-efficiency biochemical system control method according to claim 1 is characterized in that: In step S4, the control logic of the carbon source addition module is as follows: S21: Control device startup; S22: Read instrument data, including the biochemical online flow meter at the water inlet and the first online nitric nitrogen meter in the anoxic tank; S23: Periodically judge the value of the first online nitric nitrogen meter, and calculate the carbon source dosage according to the value of the first online nitric nitrogen meter and the biochemical water flow rate. All parameter values ​​must be adjustable, and an adjustment interface must be reserved. S24: Keep running.

5. The low-carbon and high-efficiency biochemical system control method according to claim 4 is characterized in that: In step S23, the specific logic is as follows: S231. When B<first online nitrate nitrogen meter<Z, keep the original dosage. When the first online nitrate nitrogen meter>Z, increase the carbon source dosage of {η*(first online nitrate nitrogen meter value-Z) / Z}, observe for one cycle, if the first online nitrate nitrogen meter value recovers to B<first online nitrate nitrogen meter<Z, keep running, if the first online nitrate nitrogen meter is still greater than Z, continue to increase the carbon source dosage until the first online nitrate nitrogen meter value recovers to B<first online nitrate nitrogen meter<Z, η is the adjustable coefficient, 1 cycle is 2 hours; Z is the recommended control value of the first online nitrate nitrogen meter, and B is the minimum value of the first online nitrate nitrogen meter; S232, when the first online nitric nitrogen meter <B adjustment decreases { *(the value of the first online nitrate nitrogen meter - Z) / Z}, observe for a period of time, if the value of the first online nitrate nitrogen meter recovers to B<the first online nitrate nitrogen meter<Z, keep running, if the first online nitrate nitrogen meter is still less than B, continue to reduce the carbon source dosage until the value of the first online nitrate nitrogen meter recovers to B<the first online nitrate nitrogen meter<Z, is the adjustable coefficient, 1 cycle is 2 hours; Z is the recommended control value of the first online nitric nitrogen meter, and B is the minimum value of the first online nitric nitrogen meter; S233, when the value of the first online nitric nitrogen meter is greater than the first set value, the system alarms and reduces the water intake. The first set value is adjusted according to the actual water outlet standard.

6. The low-carbon and high-efficiency biochemical system control method according to claim 1, characterized in that: In step S5, the carbon source addition amount is adjusted by the carbon source addition module, including the following steps: S31: Control device startup; S32: Read instrument data, including the online total nitrogen meter and biochemical online flow meter at the water inlet end; S33: The internal reflow flow is periodically calculated based on the value of the inlet water online total nitrogen meter, the biochemical inlet flow rate and the outlet water total nitrogen requirement. The specific logic is as follows: S331, setting the initial internal reflux pump frequency according to the initial internal reflux ratio, and setting the carbon source addition flow rate according to the initial first online nitric nitrogen meter; S332, the internal reflux frequency is adjusted according to the online total nitrogen TN of the influent and the online nitric nitrogen 2TNe, and is adjusted once in each cycle. The adjustment relationship is internal reflux pump frequency = ε*β*Q1*(TN-TNe) / TNe, where ε is an adjustable coefficient and β is the coefficient of internal reflux pump frequency and internal reflux pump flow rate; Q1 is the biochemical online flow rate; 1 cycle is 8 hours; S33: Keep running.

7. A low-carbon and high-efficiency biochemical system control system, characterized by: Including internal reflow control module, carbon source addition module and precise aeration module; The internal reflow control module returns the nitric nitrogen that needs to be denitrified to the anoxic tank for denitrification to achieve the effect of removing total nitrogen. According to the relationship between the inlet flow rate, the online total nitrogen of the inlet water, and the total nitrogen of the outlet water, the corresponding internal reflow ratio is calculated, and the relationship coefficient between the frequency and the flow rate is calculated according to the internal reflow pump used on site. The internal reflow frequency is output according to the required internal reflow volume to control the flow rate of the internal reflow; The carbon source dosing module uses the online nitric nitrogen meter set in the anoxic tank and the aeration tank to compare the dynamic nitric nitrogen value and change trend at the end of the anoxic tank, and then gives the current required dosage to achieve accurate control of the carbon source dosage; The precise aeration module reads the real-time value of ammonia nitrogen at the end of the aeration tank, calculates the average of the value in each cycle, and calculates the difference between the average ammonia nitrogen in this cycle and the average ammonia nitrogen in the previous cycle. The calculation result is ΔNH3-N. The range of the dissolved oxygen to be operated is determined according to the absolute value |ΔNH3-N| of ΔNH3-N, and the frequency of the aeration fan is adjusted to ensure that the dissolved oxygen value is operating in the range to be operated.

8. The low-carbon and high-efficiency biochemical system control system according to claim 7 is characterized by: It also includes accounting systems and big data simulation analysis and computing systems; The calculation system is used to automatically calculate the required air volume and carbon source amount according to the values ​​of the online monitoring instrument, and automatically calculate the nitrification liquid reflux amount according to the inlet flow rate, the inlet online total nitrogen and the outlet total nitrogen values; The big data simulation analysis and calculation system uses the fan air supply, carbon source dosage, and internal recirculation volume control as control variables and implements control through a feedback system.

9. The low-carbon and high-efficiency biochemical system control system according to claim 7 is characterized by: At the water inlet of the biochemical reaction tank, an inlet online total nitrogen meter, an inlet online ammonia nitrogen meter, an inlet online COD meter, and a biochemical online flow meter Q1 are installed; Online monitoring of total nitrogen, ammonia nitrogen and COD in the biochemical reaction pool influent, and real-time measurement of the biochemical reaction pool influent volume; The anoxic tank is equipped with online ORP, first online dissolved oxygen, and first online nitric nitrogen meters; The online monitoring instrument is used to monitor the ORP in the anoxic tank, the dissolved oxygen and nitrate nitrogen values ​​at the end of the anoxic tank in real time; 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 provide real-time monitoring and feedback of the pH, nitrate nitrogen, ammonia nitrogen, dissolved oxygen, temperature at the end of the aeration tank and the sludge concentration in the aeration tank; An online effluent total nitrogen meter, an online effluent ammonia nitrogen meter and an online effluent COD meter are installed in the sedimentation tank. Online monitoring of total nitrogen, ammonia nitrogen and COD in the effluent from the biochemical system.

10. The low-carbon and high-efficiency biochemical system control system according to claim 7, characterized in that: At the initial start-up of the control system, the initial assignment of DO, carbon source dosage, and internal reflux volume is completed based on the analysis of historical data values.

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