Sewage treatment carbon source addition control method and system based on dynamic nitrate nitrogen target value

Abstract

The invention belongs to the field of sewage treatment intelligent control, and particularly provides a sewage treatment carbon source adding control method and system based on a dynamic nitrate nitrogen target value. Dynamically calculating a nitrate nitrogen control value [NO3-N] control value at the tail end of the anoxic tank according to an effluent total nitrogen limit value, the effluent ammonia nitrogen concentration of the anoxic tank and an empirical correction value; the carbon source adding amount is adjusted by taking the control value of nitrate nitrogen at the tail end of the anoxic tank as a control target. According to the invention, the nitrate nitrogen control target of the anoxic tank can be dynamically set according to real-time water quality parameters, and accurate and optimized addition of a carbon source is realized through a feedforward-feedback double closed-loop control structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of intelligent control of sewage treatment, and particularly relates to a sewage treatment carbon source dosing control method and system based on a dynamic nitrate nitrogen target value. BACKGROUND

[0002] In the process of sewage treatment, the removal of total nitrogen (TN) is one of the key links to achieve the discharge standard. At present, sewage treatment plants generally adopt the method of dosing external carbon source (such as sodium acetate) in the anoxic tank, and convert nitrate nitrogen (NO3 － -N) into nitrogen through denitrification, so as to reduce the total nitrogen concentration of the effluent.

[0003] The traditional carbon source dosing control method mainly has the following defects: 1. Serious waste of carbon source: The existing control strategy mostly takes the "nitrate nitrogen at the end of the anoxic tank approaching 0" as the control target, ignoring the fluctuation of the influent ammonia nitrogen load. When the influent ammonia nitrogen concentration is low, excessive pursuit of nitrate nitrogen zero will result in that the total nitrogen of the effluent is far below the discharge standard, causing excessive dosing and waste of carbon source. For example, when the ammonia nitrogen concentration in the anoxic tank is 3 mg / L, if the nitrate nitrogen control target is still set to approach 0, the total nitrogen of the effluent may be as low as 4-5 mg / L, which is far below the discharge limit of 10 mg / L, and the carbon source utilization rate is low.

[0004] 2. Weak anti-interference ability: The fixed carbon-nitrogen ratio (C / N) dosing model cannot be associated with the real-time ammonia nitrogen concentration of the anoxic tank effluent, and cannot dynamically respond to the fluctuation of the influent water quality and quantity, so the system has poor anti-shock load capacity and is prone to unstable effluent quality.

[0005] 3. Large fluctuation of total nitrogen in the effluent: In actual operation, the total nitrogen concentration of the effluent usually fluctuates between 5 mg / L and 8 mg / L. Under the premise that the discharge standard is 10 mg / L, if it can be stably controlled at a level close to the standard limit (for example, 8.5 mg / L) instead of pursuing too low a value, the carbon source dosing amount can be theoretically significantly saved, but the traditional method lacks precise stable control means.

[0006] Therefore, there is an urgent need for an intelligent control method that can dynamically adjust the carbon source dosing strategy according to real-time operating conditions, to minimize carbon source consumption while ensuring that the total nitrogen in the effluent is stably up to standard. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a sewage treatment carbon source dosing control method and system based on a dynamic nitrate nitrogen target value, which can dynamically set the nitrate nitrogen control target of the anoxic tank according to real-time water quality parameters, and realize precise and optimized dosing of carbon source through a feedforward-feedback double closed-loop control structure.

[0008] To solve the above technical problems, the technical scheme adopted by the present application is: a sewage treatment carbon source dosing control method based on a dynamic nitrate nitrogen target value, comprising the following steps: Step one, ammonia nitrogen concentration of anoxic tank effluent is obtained; Step two, a dynamic calculation of anoxic tank end nitrate nitrogen control value [NO3 － -N] 控制值 is carried out according to the effluent total nitrogen limit value, the ammonia nitrogen concentration of the anoxic tank effluent and an empirical correction value. Step three, the carbon source dosing amount is adjusted with the anoxic tank end nitrate nitrogen control value [NO3 － -N] 控制值 as a control target.

[0009] In the preferred scheme, the formula for dynamically calculating the nitrate nitrogen target value in step two is: [NO3 － -N] 控制值 =[TN] 出水 -[NH3-N] 缺氧池 -K 出水 . Among them, [NO3 － -N] 控制值 is the nitrate nitrogen target value allowed to remain in the anoxic tank; [TN] 出水 is the effluent total nitrogen limit value; [NH3-N] 缺氧池 is the real-time ammonia nitrogen concentration of the anoxic tank effluent; K 出水 is an empirical correction value.

[0010] In the preferred scheme, the empirical correction value K 出水 ranges from 0.5 to 4.0 mg / L.

[0011] In the preferred scheme, the adjustment of the carbon source dosing amount in step three includes feedforward control and feedback control: the feedforward control calculates the theoretical carbon source dosing amount based on the influent chemical oxygen demand, external reflux, internal reflux and nitrate nitrogen concentration; the feedback control adjusts the dosing amount according to the deviation between the measured value of the anoxic tank end nitrate nitrogen and the anoxic tank end nitrate nitrogen control value.

[0012] In the preferred scheme, the feedforward control includes the following steps: The nitrate nitrogen load of the anaerobic tank and the anoxic tank is calculated; The total amount of nitrate nitrogen that can be removed by the influent biochemical oxygen demand is calculated; The total amount of nitrate nitrogen that needs to be removed by the dosed carbon source is calculated; The carbon source dosing amount is calculated according to the total amount of nitrate nitrogen that needs to be removed by the dosed carbon source.

[0013] In the preferred scheme, the calculation formula of the nitrate nitrogen load of the anaerobic tank and the anoxic tank is: ; Where A represents the nitrification nitrogen load of the anaerobic-anoxic tank; Q represents the influent flow rate; C1 represents the influent nitrification nitrogen concentration; C2 represents the end nitrification nitrogen concentration of the aerobic tank or the total effluent nitrification nitrogen concentration; R represents the external recirculation ratio; and r represents the internal recirculation ratio.

[0014] In the preferred embodiment, the formula for calculating the total amount of nitrate nitrogen that can be removed by the influent biochemical oxygen demand is as follows: ; Wherein, B represents the total amount of nitrate nitrogen that can be removed by the influent biochemical oxygen demand; C3 represents the concentration of influent chemical oxygen demand; f represents the ratio coefficient for converting influent chemical oxygen demand to influent biochemical oxygen demand; Q represents the influent flow rate; and K1 represents the nitrate nitrogen parameter that can be removed by influent biochemical oxygen demand.

[0015] In a preferred embodiment, the ratio coefficient f for converting the influent chemical oxygen demand (COD) to the influent biochemical oxygen demand (BOD) ranges from 0.3 to 0.6, and the nitrification nitrogen parameter K1 that the influent BOD can remove ranges from 3 to 6.

[0016] In the preferred embodiment, the formula for calculating the total amount of nitrate nitrogen to be removed by adding a carbon source is as follows: ; Among them, the total amount of nitrate nitrogen that needs to be removed by adding carbon source; A represents the nitrification nitrogen load of the anaerobic-anoxic tank; B represents the total amount of nitrate nitrogen that can be removed by the influent biological oxygen demand; [NO3] － -N] 控制值 This represents the target value for the residual nitrate nitrogen in the anoxic pond.

[0017] In the preferred embodiment, the formula for calculating the amount of carbon source added is: D = C × K² / D S ; in, D K is the carbon source dosage; K2 is the parameter for nitrate nitrogen removal by the carbon source; D S This is the COD equivalent of the carbon source solution.

[0018] In a preferred embodiment, the value of parameter K2 is in the range of 4 to 7.

[0019] In a preferred embodiment, the feedback control operation method is as follows: If [NO3] － -N] 实际值 >[NO3 － -N] 控制值+δ, where δ is the control dead zone, then the carbon source dosage increases. The dosage is added according to the proportional coefficient, which is between 1.1 and 1.5, that is, the dosage is calculated according to 1.1G~1.5G. If [NO3] － -N] 实际值 <[NO3 － -N] 控制值 -δ, the carbon source dosage decreases, and the dosage is added according to the proportional coefficient, which is between 0.7 and 0.9, that is, the dosage is calculated according to 0.6G~0.9G; If [NO3] － -N] 实际值值 =[NO3 － -N] 控制值 Maintain the current injection level.

[0020] In a preferred embodiment, the value of δ ranges from 0.2 to 0.5 mg / L.

[0021] In the preferred embodiment, when [NH3-N] 缺氧池 +K 出水 [TN] 出水 At that time, forced [NO3] － -N] 控制值 The concentration is set to 0 mg / L. At this point, the amount of carbon source added in step three is increased to 115-150% of the theoretical amount of carbon source added.

[0022] The present invention also provides a wastewater treatment carbon source dosing control system based on a dynamic nitrate nitrogen target value, for executing the above-described control method, comprising: An online ammonia nitrogen analyzer is used to monitor the ammonia nitrogen concentration in the effluent of anoxic ponds. Nitrate nitrogen sensor, used to monitor nitrate nitrogen concentration at the end of aerobic tank and / or the end of anoxic tank; The program module is used to perform the calculation of carbon source dosage; The PLC controller is used to implement the carbon source dosing control logic. A carbon source dosing actuator is used to perform carbon source dosing operations.

[0023] In a preferred embodiment, the PLC controller is configured as follows: If [NO3] － -N] 实际值 >[NO3 － -N] 控制值 +δ, where δ is the control dead zone, then the carbon source dosage increases. The dosage is added according to the proportional coefficient, which is between 1.1 and 1.5, that is, the dosage is calculated according to 1.1G~1.5G. If [NO3] － -N] 实际值<[NO3 － -N] 控制值 -δ, the carbon source dosage decreases, and the dosage is added according to the proportional coefficient, which is between 0.7 and 0.9, that is, the dosage is calculated according to 0.6G~0.9G; If [NO3] － -N] 实际值 =[NO3 － -N] 控制值 Maintain the current injection level.

[0024] The present invention provides a wastewater treatment carbon source addition control method and system based on dynamic nitrate nitrogen target value, which has the following beneficial effects: 1. By introducing a dynamic nitrate nitrogen target value, the anoxic tank is allowed to retain an appropriate amount of nitrate nitrogen when the ammonia nitrogen load is low, thus avoiding unnecessary carbon source consumption.

[0025] 2. The feedforward-feedback dual closed-loop control structure effectively resists influent load fluctuations, enabling the total nitrogen in the effluent to be stably controlled near the set value (e.g., 8.0 mg / L), reducing the range of water quality fluctuations and improving the reliability of system operation.

[0026] 3. The dynamic target value mechanism and real-time feedback adjustment work together to enable the system to respond quickly and adapt to changes in water quality and quantity, demonstrating excellent robustness.

[0027] 4. Negative value protection strategy: When [NH3-N] 缺氧池 +K 出水 When >TN, force [NO3] - When -N] is 0, an emergency dosing mode is triggered. The built-in negative value protection strategy can automatically activate the emergency mode under high load shocks to maximize the removal of nitrate nitrogen and ensure that the effluent meets the standards, thereby reducing operational risks. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0029] Example 1: A wastewater treatment carbon source dosing control method based on dynamic nitrate nitrogen target values ​​includes the following steps: Step 1: Obtain the ammonia nitrogen concentration in the effluent from the anoxic tank. The ammonia nitrogen concentration [NH3-N] in the effluent of the anoxic tank was obtained through real-time monitoring using an online ammonia nitrogen analyzer. 缺氧池 As an alternative, the influent ammonia nitrogen concentration, internal reflux ratio (r), and external reflux ratio (R) can be used to determine the concentration of [NH3-N] using the formula [NH3-N]. 缺氧池=[NH3-N] 进水 The calculation is performed using / (1+r+R) to estimate the value.

[0030] Acquiring real-time ammonia nitrogen data from the anoxic tank provides a core input variable for dynamically calculating the target value of nitrate nitrogen, ensuring that the control strategy can respond to changes in influent load.

[0031] Step 2: Dynamically calculate the control value of nitrate nitrogen at the end of the anoxic tank. Based on the set total nitrogen limit [TN] in the effluent 出水 The ammonia nitrogen concentration [NH3-N] in the effluent from the anoxic tank obtained in step one. 缺氧池 and the experience correction value K 出水 The target value of nitrate nitrogen [NO3] allowed to remain at the end of the anoxic tank is dynamically calculated using the following formula. － -N] 控制值 : [NO3 － -N] 控制值 =[TN] 出水 -[NH3-N] 缺氧池 -K 出水 ; Among them, [NO3] － -N] 控制值 [TN] represents the target value for residual nitrate nitrogen in anoxic ponds. 出水 This refers to the total nitrogen limit for effluent; [NH3-N] 缺氧池 Real-time ammonia nitrogen concentration in the effluent from the anoxic tank; K 出水 This is an empirically corrected value.

[0032] Among them, K 出水 This represents the empirical value of the concentration of nitrogen in the effluent other than ammonia nitrogen and nitrate nitrogen (mainly organic nitrogen), typically ranging from 0.5 to 4.0 mg / L, preferably from 1.0 to 2.5 mg / L. This value can be dynamically corrected by averaging the difference between the measured total nitrogen and nitrate nitrogen and ammonia nitrogen values ​​over multiple days.

[0033] Breaking away from the traditional mindset that nitrate nitrogen must be close to zero, this approach directly links control targets to achieving the required total nitrogen level in the effluent. When ammonia nitrogen levels are low in the anoxic tank, higher nitrate nitrogen levels are allowed to be maintained to avoid wasting carbon sources; conversely, when ammonia nitrogen levels are high in the anoxic tank, lower nitrate nitrogen levels are required to prevent the effluent from exceeding the standard. This achieves "on-demand control."

[0034] Step 3: Adjust the carbon source dosage based on dynamic target values The [NO3] calculated in step two － -N] 控制值 With the goal of adjusting the amount of carbon source added, a feedforward-feedback dual closed-loop control structure is used.

[0035] 1. Feedforward control Feedforward control predictively calculates the theoretical carbon source dosage based on the system influent load and return flow conditions, specifically including: 1) Calculate the nitrate nitrogen loading (A) in the anaerobic-anoxic tank: ; Where A represents the nitrification nitrogen load of the anaerobic-anoxic tank; Q represents the influent flow rate; C1 represents the influent nitrification nitrogen concentration; C2 represents the end nitrification nitrogen concentration of the aerobic tank or the total effluent nitrification nitrogen concentration; R represents the external recirculation ratio; and r represents the internal recirculation ratio.

[0036] The total nitrate nitrogen load entering the anoxic zone was accurately quantified, providing a basis for carbon source demand forecasting.

[0037] 2) Calculate the total amount of nitrate nitrogen (B) that can be removed by the influent BOD: ; Wherein, B represents the total amount of nitrate nitrogen that can be removed by the influent biochemical oxygen demand; C3 represents the concentration of influent chemical oxygen demand; f represents the ratio coefficient for converting influent chemical oxygen demand to influent biochemical oxygen demand (range 0.3~0.6); Q represents the influent flow rate; K1 represents the nitrate nitrogen parameter that can be removed by influent biochemical oxygen demand (range 3~6, ​​theoretical value 2.86).

[0038] By making full use of the internal carbon source in the influent for denitrification, dependence on external carbon sources is reduced, thus lowering operating costs.

[0039] 3) Calculate the total amount of nitrate nitrogen (C) that needs to be removed by adding a carbon source: ; Among them, the total amount of nitrate nitrogen that needs to be removed by adding carbon source; A represents the nitrification nitrogen load of the anaerobic-anoxic tank; B represents the total amount of nitrate nitrogen that can be removed by the influent biological oxygen demand; [NO3] － -N] 控制值 This represents the target value for the residual nitrate nitrogen in the anoxic pond.

[0040] This calculation is the first to incorporate the dynamic target value of nitrate nitrogen [NO3]. － -N] 控制值 By introducing a feedforward model, not only is the nitrate nitrogen load (AB) that needs to be removed considered, but the amount of nitrate nitrogen that the system is allowed to retain is also deducted, making the calculation of carbon source addition more accurate and avoiding excessive addition from the source.

[0041] 4) Calculate the carbon source dosage (D): D = C × K² / D S ; in, DK2 is the amount of carbon source added; D is the denitrification coefficient (range 4~7) of the added carbon source (such as sodium acetate). S The COD equivalent of the carbon source solution (e.g., 200,000 mg / L or 500,000 mg / L).

[0042] The amount of nitrate nitrogen to be removed is converted into a specific carbon source dosage, parameters K2 and D. S It can be calibrated according to the actual type and concentration of carbon source, which improves the applicability and accuracy of control.

[0043] 2. Feedback control Feedback control is based on the measured value of nitrate nitrogen sensor at the end of the anoxic tank [NO3]. － -N] 实际值 With the target value [NO3] － -N] 控制值 To address the deviation, the feedforward-calculated dosage D is fine-tuned in real time. If [NO3] － -N] 实际值 >[NO3 － -N] 控制值 +δ, where δ is the control dead zone, 0.2~0.5 mg / L, then the dosage should be increased proportionally (proportioning coefficient 1.1~1.5).

[0044] If [NO3] － -N] 实际值 <[NO3 － -N] 控制值 If -δ is applied, the dosage will be reduced proportionally (proportion coefficient 0.6~0.9).

[0045] If the deviation is within the dead zone, maintain the current dosage.

[0046] Preferably, when [NH3-N] 缺氧池 +K 出水 [TN] 出水 At that time, forced [NO3] － -N] 控制值 The concentration is set to 0 mg / L. At this point, the amount of carbon source added in step three is increased to 115-150% of the theoretical amount of carbon source added.

[0047] Feedback control can overcome feedforward model errors and unforeseen process disturbances, and make real-time and accurate corrections to the dosage, ensuring that the system operates stably near the set dynamic target value, thus significantly improving the system's anti-interference capability and control accuracy.

[0048] Example 2: A municipal wastewater treatment plant with a capacity of 80,000 tons / day (effluent TN standard ≤10mg / L) To ensure a safe margin for effluent discharge, a control target [TN] is set. 出水 =8.0 mg / L. An empirical correction value K was determined through long-term monitoring. 出水 =1.3 mg / L. At a certain moment, the online ammonia nitrogen analyzer measured the ammonia nitrogen concentration [NH3-N] in the effluent of the anoxic tank. 缺氧池 =4.5mg / L.

[0049] 1. Dynamically calculate the nitrate nitrogen control value: [NO3 － -N] 控制值 =8.0-4.5-1.3=2.2 mg / .

[0050] Traditional methods require a control value of <0.5 mg / L, while this invention allows it to be maintained at 2.2 mg / L, saving a significant amount of carbon source.

[0051] 2. Feedforward calculation of carbon source dosage: Based on the real-time influent flow rate Q, COD concentration C3, nitrate nitrogen concentration C1, nitrate nitrogen at the end of the aerobic tank C2, and reflux ratios R and r, combined with parameters f=0.5, K1=4.0, K2=4.0, and Ds=200000mg / L, the baseline carbon source dosage D is calculated.

[0052] Feedback adjustment: The measured value of nitrate nitrogen at the end of the anoxic tank was 2.6 mg / L, and the control dead zone δ = 0.3 mg / L. Since 2.6 mg / L > (2.2 + 0.3) mg / L, the dosage was increased by a proportionality factor of 1.2, and the actual dosage was 1.2D.

[0053] Under this control, the carbon source dosage of the plant was reduced from the traditional 10 tons / day to 3 tons / day, and the total nitrogen in the effluent was stabilized at around 8.2 mg / L, achieving a significant saving of carbon source and stable compliance with effluent standards.

[0054] Example 3: At a certain moment, the system detected a sharp increase in the ammonia nitrogen concentration [NH3-N] in the effluent from the anoxic tank. 缺氧池 =7.0 mg / L, K 出水 Still at 1.3 mg / L, [TN] 出水 =8.0 mg / L.

[0055] 1. Dynamically calculate the nitrate nitrogen control value: [NO3 － -N] 控制值 =8.0-7.0-1.3=−0.3 mg / L. The system triggers negative value protection and forces a setting of [NO3]. － -N] 控制值 =0 mg / L.

[0056] 2. Controlling actions: The system implements emergency control, increasing the carbon source dosage to 130% of the feedforward baseline value D, and continuously monitors it. If the measured nitrate nitrogen is still above 0, the dosage is further increased through the feedback loop.

[0057] This mechanism effectively addresses high ammonia nitrogen load shocks by maximizing carbon source addition and denitrification efficiency, striving to control total nitrogen in the effluent to within limits, and ensuring operational safety.

[0058] Example 4: Scenario 1: Low ammonia nitrogen condition, with total nitrogen in the effluent controlled at 8 mg / L, [NH3-N] 缺氧池 =3.2mg / L.

[0059] [NO3 － -N] 控制值 =8-3.2-1.3=3.5 mg / L, and the carbon source dosage is calculated according to the formula in Example 1.

[0060] Adjust the carbon source dosage according to the nitrification nitrogen concentration in the anoxic tank. If [NO3] － -N] 实际值 >3.5, increase the amount of carbon source added, if [NO3] － -N] 实际值 <3.5, reduce the amount of carbon source added.

[0061] Scenario 2: High ammonia nitrogen conditions, with total nitrogen in the effluent controlled at 8 mg / L.

[0062] [NH3-N] 缺氧池 =7mg / L, nitrate nitrogen control value in anoxic pond [NO3] － -N] 控制值 =8-7-1.3=-0.3mg / L, calculate the carbon source dosage according to the formula in Example 1. If the anoxic tank [NO3] － -N] 实际值 >0, increase the amount of carbon source added, if [NO3] － -N] 实际值 <0, reduce the amount of carbon source added.

[0063] Table 1 compares the effects of the present invention with those of traditional methods.

[0064]

[0065] Data from the examples show that, compared to the traditional method of adding 10 tons of carbon source per day, the present invention can reduce the addition amount to about 3 tons per day, saving 70%, while the total nitrogen in the effluent remains stable at 8.2 mg / L, consistently meeting the standard.

[0066] Example 5: The present invention also provides a control system for performing the above method, comprising: Online ammonia nitrogen analyzer: used for real-time monitoring of ammonia nitrogen concentration in the effluent of anoxic ponds.

[0067] Nitrate nitrogen sensors: installed at the end of the aerobic tank and the end of the anoxic tank respectively, to monitor nitrate nitrogen concentration.

[0068] Program module: Embedded in the PLC or host computer, used to execute all the above calculation logic.

[0069] PLC controller: Receives sensor signals and calculation results from program modules, executes control logic, and outputs control commands.

[0070] Carbon source dosing actuator: such as a metering pump, which receives PLC commands and accurately adds carbon source.

[0071] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value, characterized in that, Includes the following steps: Step 1: Obtain the ammonia nitrogen concentration in the effluent from the anoxic tank; Step 2: Based on the total nitrogen limit in the effluent, the ammonia nitrogen concentration in the effluent from the anoxic tank, and the empirical correction value, dynamically calculate the nitrate nitrogen control value [NO3] at the end of the anoxic tank. － -N] 控制值 ; Step 3: Control the nitrate nitrogen content at the end of the anoxic tank [NO3] － -N] 控制值 To control the target, the amount of carbon source added is adjusted.

2. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 1, characterized in that, In step two, the formula for dynamically calculating the target value of nitrate nitrogen is: [NO3 － -N] 控制值 =[TN] 出水 -[NH3-N] 缺氧池 -K 出水 ; Among them, [NO3] － -N] 控制值 [TN] represents the target value for residual nitrate nitrogen in anoxic ponds. 出水 This refers to the total nitrogen limit for effluent; [NH3-N] 缺氧池 Real-time ammonia nitrogen concentration in the effluent from the anoxic tank; K 出水 This is an empirically corrected value.

3. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 2, characterized in that, The empirical correction value K 出水 The value range is 0.5~4.0 mg / L.

4. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 1, characterized in that, In step three, the adjustment of carbon source dosage includes feedforward control and feedback control: feedforward control calculates the theoretical carbon source dosage based on influent chemical oxygen demand, external reflux, internal reflux, and nitrate nitrogen concentration; feedback control adjusts the dosage according to the deviation between the measured value of nitrate nitrogen at the end of the anoxic tank and the controlled value of nitrate nitrogen at the end of the anoxic tank.

5. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 4, characterized in that, The feedforward control includes the following steps: Calculate the nitrate nitrogen load in the anaerobic and anoxic tanks; Calculate the total amount of nitrate nitrogen that can be removed by the influent biochemical oxygen demand; Calculate the total amount of nitrate nitrogen that needs to be removed by adding a carbon source; The amount of carbon source to be added is calculated based on the total amount of nitrate nitrogen to be removed by the carbon source.

6. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 5, characterized in that, The formula for calculating the nitrate nitrogen load in the anaerobic and anoxic tanks is as follows: ； Where A represents the nitrification nitrogen load of the anaerobic-anoxic tank; Q represents the influent flow rate; C1 represents the influent nitrification nitrogen concentration; C2 represents the end nitrification nitrogen concentration of the aerobic tank or the total effluent nitrification nitrogen concentration; R represents the external recirculation ratio; and r represents the internal recirculation ratio.

7. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 5, characterized in that, The formula for calculating the total amount of nitrate nitrogen that can be removed by the influent biochemical oxygen demand is as follows: ； Wherein, B represents the total amount of nitrate nitrogen that can be removed by the influent biochemical oxygen demand; C3 represents the concentration of influent chemical oxygen demand; f represents the ratio coefficient for converting influent chemical oxygen demand to influent biochemical oxygen demand; Q represents the influent flow rate; and K1 represents the nitrate nitrogen parameter that can be removed by influent biochemical oxygen demand.

8. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 7, characterized in that, The ratio of the influent chemical oxygen demand (COD) to influent biochemical oxygen demand (BOD) is in the range of 0.3 to 0.6, and the nitrification parameter K1 that can be removed by the influent biochemical oxygen demand is in the range of 3 to 6.

9. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 5, characterized in that, The formula for calculating the total amount of nitrate nitrogen that needs to be removed by adding a carbon source is as follows: ； Among them, the total amount of nitrate nitrogen that needs to be removed by adding carbon source; A represents the nitrification nitrogen load of the anaerobic-anoxic tank; B represents the total amount of nitrate nitrogen that can be removed by the influent biological oxygen demand; [NO3] － -N] 控制值 This represents the target value for the residual nitrate nitrogen in the anoxic pond.

10. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 5, characterized in that, The formula for calculating the amount of carbon source added is as follows: D=C×K2 / D S ; in, D K is the carbon source dosage; K2 is the parameter for nitrate nitrogen removal by the carbon source; D S This is the COD equivalent of the carbon source solution.

11. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 10, characterized in that, The value of parameter K2 ranges from 4 to 7.

12. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 4, characterized in that, The feedback control operation method is as follows: If [NO3] － -N] 实际值 >[NO3 － -N] 控制值 +δ, where δ is the control dead zone, then the carbon source dosage increases. The dosage is added according to the proportional coefficient, which is between 1.1 and 1.5, that is, the dosage is calculated according to 1.1G~1.5G. If [NO3] － -N] 实际值 <[NO3 － -N] 控制值 -δ, the carbon source dosage decreases, and the dosage is added according to the proportional coefficient, which is between 0.7 and 0.9, that is, the dosage is calculated according to 0.6G~0.9G; If [NO3] － -N] 实际值 =[NO3 － -N] 控制值 Maintain the current injection level.

13. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 12, characterized in that, The value of δ ranges from 0.2 to 0.5 mg / L.

14. The wastewater treatment carbon source addition control method based on dynamic nitrate nitrogen target value according to claim 4, characterized in that, When [NH3-N] 缺氧池 +K 出水 [TN] 出水 At that time, forced [NO3] － -N] 控制值 The concentration is set to 0 mg / L. At this point, the amount of carbon source added in step three is increased to 115-150% of the theoretical amount of carbon source added.

15. A wastewater treatment carbon source dosing control system based on dynamic nitrate nitrogen target values, characterized in that, For performing the control method according to any one of claims 1 to 13, comprising: An online ammonia nitrogen analyzer is used to monitor the ammonia nitrogen concentration in the effluent of anoxic ponds. Nitrate nitrogen sensor, used to monitor nitrate nitrogen concentration at the end of aerobic tank and / or the end of anoxic tank; The program module is used to perform the calculation of carbon source dosage; The PLC controller is used to implement the carbon source dosing control logic. A carbon source dosing actuator is used to perform carbon source dosing operations.

16. A wastewater treatment carbon source dosing control system based on a dynamic nitrate nitrogen target value as described in claim 15, characterized in that, The PLC controller is configured as follows: If [NO3] － -N] 实际值 >[NO3 － -N] 控制值 +δ, where δ is the control dead zone, then the carbon source dosage increases. The dosage is added according to the proportional coefficient, which is between 1.1 and 1.5, that is, the dosage is calculated according to 1.1G~1.5G. If [NO3] － -N] 实际值 <[NO3 － -N] 控制值 -δ, the carbon source dosage decreases, and the dosage is added according to the proportional coefficient, which is between 0.7 and 0.9, that is, the dosage is calculated according to 0.6G~0.9G; If [NO3] － -N] 实际值 =[NO3 － -N] 控制值 Maintain the current injection level.

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