Accurate carbon source adding system for sewage plant and control method of accurate carbon source adding system

Abstract

The invention discloses a sewage plant carbon source accurate adding system and a control method thereof, and relates to the technical field of sewage treatment. A sewage plant carbon source accurate adding system comprises a sewage treatment unit, a chemical adding unit and a control unit, the sewage treatment unit comprises a biological tank and a secondary sedimentation tank, an outer backflow pipeline is arranged between the biological tank and the secondary sedimentation tank, the secondary sedimentation tank is communicated with the biological tank through the outer backflow pipeline, and the chemical adding unit is connected with the control unit. Wherein the biological tank comprises an anaerobic tank, an anoxic tank and an aerobic tank; based on the control unit, the theoretical dosage is calculated according to the nitrate nitrogen load needing to be removed by the external carbon source in the anoxic zone, feedforward calculation is performed on the effluent nitrate nitrogen target value of the anoxic zone, feedback calculation is performed according to the deviation between the actual measurement value and the target value of the effluent nitrate nitrogen of the anoxic zone, and the dosage is adjusted by combining feedforward and feedback calculation results. Therefore, accurate dosing of the sewage treatment unit is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a precise carbon source dosing system for a sewage treatment plant and a control method thereof. Background Art

[0002] At present, due to the rapid development of society and the intensification of urbanization construction, the operation of urban sewage treatment plants has entered a period of efficient operation. With the improvement of economic levels in various places, environmental pressure has increased, emission standards have been raised, and environmental law enforcement has been strengthened, especially the emission requirements of TN and TP, which are too high to cause eutrophication of water bodies. The pressure of meeting emission standards faced by sewage treatment plants has increased. At the same time, they are facing the need to increase efficiency and develop in the direction of energy conservation and consumption reduction, responding to the social energy conservation and emission reduction goals. The denitrification process of urban sewage treatment plants mainly sets up anoxic tanks, denitrification filters, etc., so that ammonia nitrogen is denitrified after nitrification, and denitrification occurs in the above process section to produce N2 to achieve the purpose of denitrification. The carbon source in sewage can generally meet the denitrification needs, but to meet the requirements of high emission standards, it is usually necessary to add an external carbon source. The external carbon source added is generally acetic acid or sodium acetate. The addition method is mainly constant addition, and it is manually adjusted according to the treatment effect. It often occurs that TN exceeds the standard due to untimely adjustment of water quality and water volume fluctuations, and the addition amount is too large. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a sewage treatment plant carbon source precision dosing system and a control method thereof which can overcome the above problems or at least partially solve the above problems.

[0004] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is: a precise carbon source dosing system for a sewage treatment plant, including a sewage treatment unit, a dosing unit and a control unit, and also includes: the sewage treatment unit includes a biological pool and a secondary sedimentation tank, an external return pipe is arranged between the biological pool and the secondary sedimentation tank, and the secondary sedimentation tank is connected with the biological pool through the external return pipe, wherein the biological pool includes an anaerobic pool, an anoxic pool and an aerobic pool, an internal return pipe is arranged between the anoxic pool and the aerobic pool, and a nitrate concentration meter is arranged at the outlet of the anoxic pool, an internal return flow meter is arranged on the internal return pipe, and an external return flow meter is arranged on the external return pipe, an inlet flow meter, a COD meter and an inlet ammonia nitrogen meter are arranged at the water inlet of the sewage treatment unit, and an outlet total nitrogen meter is arranged at the total outlet of the sewage treatment unit.

[0005] Preferably, a carbon source addition point is provided at the front end of the anoxic tank, and the carbon source tank is connected to the carbon source addition point of the anoxic tank through a pipeline.

[0006] Furthermore, it includes a feedforward control unit and a feedback control unit, the feedforward control unit includes a feedforward signal acquisition and calculation unit, the feedforward signal acquisition unit is used to acquire the signal required for feedforward control, and the feedforward built-in calculation unit is used to calculate the dosage according to the acquired feedforward signal; and the feedback control unit includes a feedback signal acquisition and calculation unit, the feedback signal acquisition unit is used to acquire the signal required for feedback control, and the feedback built-in calculation unit is used to calculate the dosage adjustment value according to the acquired feedback signal.

[0007] Preferably, a liquid level meter is provided on the carbon source storage tank of the dosing unit for measuring the liquid level of the carbon source in the carbon source storage tank; a diaphragm metering pump is provided between the carbon source storage tank and the carbon source addition point for conveying the carbon source; and an electric valve and a dosing flow meter are provided at the water outlet of the diaphragm metering pump for controlling the dosing flow.

[0008] Preferably, a method for controlling a precise carbon source dosing system in a sewage treatment plant comprises the following specific steps:

[0009] S10, collecting signals of water inlet flow rate, water inlet total nitrogen meter monitoring value, water inlet COD meter monitoring value, nitrate concentration meter, total effluent total nitrogen value, internal reflux flow rate, external reflux flow rate, dosing pump frequency, drug storage tank liquid level, dosing pump flow rate and dosing room equipment operation status through the signal acquisition unit in the control unit;

[0010] S20, using the feedforward control unit and the feedback control unit in the model calculation unit to calculate the signal collected in step S10 as the dosage or dosage adjustment value through the built-in calculation unit;

[0011] S30, converting the calculated dosage or dosage adjustment value into the operating frequency of the dosing pump through the dosing pump control unit, and then converting it into a control signal output to the programmable logic controller to control the operation of the dosing pump to achieve accurate dosing.

[0012] Furthermore, the specific process of step S20 is: using the feedforward signal acquisition unit in the feedforward control unit to acquire the signal required for the feedforward control, the feedforward built-in calculation unit in the feedforward control unit calculates the dosage, using the feedback signal acquisition unit in the feedback control unit to acquire the signal required for the feedback control, and the feedback built-in calculation unit in the feedback control unit calculates the dosage adjustment value; wherein, an inlet flow meter and a COD meter are provided at the water inlet of the sewage treatment unit, and the theoretical dosage is calculated according to the nitrate nitrogen load and the COD load entering the anoxic tank, and the nitrate nitrogen concentration control target value at the outlet of the anoxic tank is calculated; the feedback control includes providing a nitrate concentration meter at the outlet of the anoxic tank, and performing feedback adjustment according to the deviation of the nitrate nitrogen concentration at the outlet of the anoxic tank from the target value.

[0013] Further, in step S20, the feedforward control unit calculates the dosage based on the nitrate nitrogen concentration of the anoxic tank effluent, the COD concentration of the inlet water, the inlet flow rate, the internal reflux flow rate, and the external reflux flow rate as follows:

[0014] q=0.02027×α×β1×(0.006×S COD -0.12)×Q

[0015] Where: q——dosing pump flow rate, L / h;

[0016] Q——water inlet flow, m 3 / h;

[0017] S COD ——Influent COD concentration, mg / L;

[0018] β1——feedforward dosing coefficient;

[0019] α——Safety factor, 1.05~1.20.

[0020] Further, in step S20, the feedback control unit performs feedback adjustment based on the deviation of the nitric nitrogen concentration at the outlet of the anoxic tank and the target value:

[0021]

[0022] in: ——Nitrates nitrogen concentration in the effluent of the anoxic pool, mg / L;

[0023] S NO,sp ——Target value of nitrate nitrogen concentration at the outlet of anoxic pool, mg / L;

[0024] Q——water inlet flow, m 3 / h;

[0025] Q1——Internal reflux flow, m 3 / h;

[0026] Q2——external return flow, m 3 / h;

[0027] β2——Feedback dosing coefficient.

[0028] Preferably, in step S30, the dosing pump control unit is adjusted using a closed-loop automatic control technology, and a trial-and-error method is used to determine PID parameters, thereby adjusting the frequency of the dosing pump to stabilize the flow rate of the dosing pump near the set flow rate.

[0029] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0030] 1. The precise carbon source dosing system of the sewage treatment plant is equipped with an online nitrate nitrogen monitor at the outlet of the aerobic pool, flow meters at the internal return pipe and the external return pipe, and flow meters and COD meters at the water inlet of the sewage treatment plant. The theoretical dosage is calculated according to the nitrate nitrogen load and COD load entering the anoxic zone, and the nitrate nitrogen concentration control target value at the anoxic outlet is calculated; an online nitrate nitrogen monitor is installed at the outlet of the anoxic pool, and feedback adjustment is performed according to the deviation of the nitrate nitrogen concentration at the anoxic outlet from the target value.

[0031] 2. The precise carbon source dosing system of the sewage treatment plant calculates the feedforward dosage according to the nitrate nitrogen load of the influent of the anoxic tank and the target value of the nitrate nitrogen concentration at the outlet of the anoxic tank; the feedback control component automatically adjusts the dosage according to the deviation between the nitrate nitrogen concentration at the outlet of the anoxic tank and the target value, so that the nitrate nitrogen concentration in the effluent is stabilized near the control value, thus saving the dosage of the agent to the greatest extent.

[0032] 3. The precise carbon source dosing system of the sewage treatment plant not only solves the problem of rough addition of external carbon sources to the sewage treatment plant, but also increases the stability of effluent, and solves the problem of lag between dosing and effluent quality reaching the standard to the greatest extent, making the sewage treatment plant management move towards refinement.

[0033] The parts not involved in the precise carbon source dosing system of the sewage treatment plant are the same as the prior art or can be implemented by the prior art. The present invention can calculate the theoretical dosage and perform feedforward calculation on the target value of nitrate nitrogen in the effluent of the anoxic section based on the nitrate nitrogen load that needs to be removed by adding an external carbon source in the anoxic section based on the control unit, perform feedback calculation based on the deviation between the actual measured value of nitrate nitrogen in the effluent of the anoxic section and the target value, and adjust the dosage based on the feedforward and feedback calculation results, thereby realizing precise dosing of the sewage treatment unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of a flow chart of a carbon source precise dosing system for a sewage treatment plant and a control method thereof proposed by the present invention;

[0035] Figure 2 This is a structural schematic diagram of a dosing unit of a sewage treatment plant carbon source precise dosing system and a control method thereof proposed by the present invention;

[0036] Figure 3 The present invention provides a structural schematic diagram of a sewage treatment plant carbon source precise dosing system and a control method control unit thereof. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0038] Example 1: Reference Figure 1-Figure 3 , a precise carbon source dosing system for a sewage treatment plant, comprising a sewage treatment unit, a dosing unit and a control unit, and also comprising: the sewage treatment unit comprises a biological pool and a secondary sedimentation tank, an external return pipe is arranged between the biological pool and the secondary sedimentation tank, the secondary sedimentation tank is connected with the biological pool through the external return pipe, wherein the biological pool comprises an anaerobic pool, an anoxic pool and an aerobic pool, an internal return pipe is arranged between the anoxic pool and the aerobic pool, a nitrate concentration meter is arranged at the outlet of the anoxic pool, an internal return flow meter is arranged on the internal return pipe, an external return flow meter is arranged on the external return pipe, an inlet flow meter, a COD meter and an inlet ammonia nitrogen meter are arranged at the water inlet of the sewage treatment unit, and an outlet total nitrogen meter is arranged at the total outlet of the sewage treatment unit.

[0039] In the present invention, Figure 1 As shown, the sewage treatment unit includes an anaerobic tank, an anoxic tank, an aerobic tank, and a secondary sedimentation tank. The carbon source addition point is set at the front end of the anoxic tank. In the sewage treatment unit, the number of the anaerobic tank, the anoxic tank, the aerobic tank, and the secondary sedimentation tank can be set to one or more according to specific needs. A nitrate concentration meter is set at the outlet of the anoxic tank, an internal reflux flow meter is set on the internal reflux pipe, and an external reflux flow meter is set on the external reflux pipe. In addition, an inlet flow meter, a COD meter, and an inlet total nitrogen meter are set at the water inlet of the sewage treatment unit of the sewage plant, and an outlet total nitrogen meter is set at the total outlet of the sewage treatment unit.

[0040] When in use, the sewage to be treated passes through the anaerobic tank, the anoxic tank, the aerobic tank, and the secondary sedimentation tank in sequence, and then is discharged after deep treatment and disinfection.

[0041] Example 2: Reference Figure 1-Figure 3 , a precise carbon source dosing system for a sewage treatment plant, which is basically the same as Example 1, and further: a carbon source dosing point is set at the front end of the anoxic tank, and the carbon source tank is connected to the carbon source dosing point of the anoxic tank through a pipeline; it includes a feedforward control unit and a feedback control unit, the feedforward control unit includes a feedforward signal acquisition and calculation unit, the feedforward signal acquisition unit is used to acquire the signal required for feedforward control, and the feedforward built-in calculation unit is used to calculate the dosage according to the acquired feedforward signal; and the feedback control unit includes a feedback signal acquisition and calculation unit, the feedback signal acquisition unit is used to acquire the signal required for feedback control, and the feedback built-in calculation unit is used to calculate the dosage adjustment value according to the acquired feedback signal; a liquid level meter is set on the carbon source storage tank of the dosing unit, which is used to measure the liquid level of the carbon source in the carbon source storage tank; a diaphragm metering pump is set between the carbon source storage tank and the carbon source dosing point, which is used to transport the carbon source; and an electric valve and a dosing flowmeter are set at the water outlet of the diaphragm metering pump, which are used to control the dosing flow.

[0042] like Figure 2As shown, the dosing unit includes a carbon source storage tank, a liquid level meter, a diaphragm metering pump, an electric valve and a dosing flow meter. The carbon source storage tank is connected to the carbon source dosing point at the front end of the anoxic tank through a pipeline. The carbon source storage tank is provided with a liquid level meter for measuring the liquid level of the carbon source in the carbon source storage tank. A diaphragm metering pump is provided between the carbon source storage tank and the carbon source dosing point for conveying the carbon source, and an electric valve and a dosing flow meter are provided at the water outlet of the diaphragm metering pump for controlling the dosing flow. The dosing pump flow is adjusted by a fixed stroke frequency modulation. The carbon source is selected as a composite carbon source. It is worth noting that other types of carbon sources, such as glucose, can also be selected.

[0043] Example 3: Reference Figure 1-Figure 3 , a method for controlling a precise carbon source dosing system in a sewage treatment plant, the specific steps of which include:

[0044] S10, collecting signals of water inlet flow rate, water inlet total nitrogen meter monitoring value, water inlet COD meter monitoring value, nitrate concentration meter, total effluent total nitrogen value, internal reflux flow rate, external reflux flow rate, dosing pump frequency, drug storage tank liquid level, dosing pump flow rate and dosing room equipment operation status through the signal acquisition unit in the control unit;

[0045] S20, using the feedforward control unit and the feedback control unit in the model calculation unit to calculate the signal collected in step S10 as the dosage or dosage adjustment value through the built-in calculation unit;

[0046] S30, converting the calculated dosage or dosage adjustment value into the operating frequency of the dosing pump through the dosing pump control unit, and then converting it into a control signal output to the programmable logic controller to control the operation of the dosing pump to achieve accurate dosing.

[0047] In the present invention, the sewage to be treated is sequentially treated in an anaerobic tank, an anoxic tank, an aerobic tank and a secondary sedimentation tank, and then discharged after a deep treatment process and disinfection; a total nitrogen online monitor arranged at a water inlet and a water outlet monitors the total nitrogen concentration value in water in real time, and transmits the values ​​of the inlet total nitrogen concentration and the outlet total nitrogen concentration to a main controller respectively; a COD meter arranged at the water inlet monitors the COD concentration value in water in real time, and transmits the inlet COD concentration value to the main controller; a nitrate concentration meter arranged at the outlet of the anoxic tank monitors the nitrate nitrogen concentration in water in real time, and transmits the detected nitrate nitrogen concentration to the main controller; a carbon source dosing point is the front end of the anoxic tank, the carbon source used is sodium acetate, the mass fraction of the effective component is 26.8%, and the feedforward dosing amount is determined according to the nitrate nitrogen concentration of the aerobic tank outlet, the inlet COD concentration, the inlet flow rate, the internal reflux flow rate and the external reflux flow rate.

[0048] Example 4: Reference Figure 1-Figure 3, a precise carbon source dosing system for a sewage treatment plant, which is basically the same as Example 3, and further: the specific process of step S20 is: using the feedforward signal acquisition unit in the feedforward control unit to acquire the signal required for the feedforward control, the feedforward built-in calculation unit in the feedforward control unit calculates the dosage, using the feedback signal acquisition unit in the feedback control unit to acquire the signal required for the feedback control, and the feedback built-in calculation unit in the feedback control unit calculates the dosage adjustment value; wherein, an inlet flow meter and a COD meter are arranged at the water inlet of the sewage treatment unit, and the theoretical dosage is calculated according to the nitrate nitrogen load and COD load entering the anoxic tank, and the nitrate nitrogen concentration control target value at the outlet of the anoxic tank is calculated; the feedback control includes setting a nitrate concentration meter at the outlet of the anoxic tank, and performing feedback adjustment according to the deviation of the nitrate nitrogen concentration at the outlet of the anoxic tank and the target value.

[0049] In the present invention, by real-time monitoring of the nitrate concentration at the outlet of the anoxic tank and comparing it with the target value, the system can accurately calculate the adjustment value of the dosage. This adjustment method based on actual operation data helps to ensure that the effluent quality continues to meet the standard, and when the inlet water quality or treatment conditions change, the system can quickly sense and make corresponding adjustments, thereby effectively responding to various emergencies and reducing water quality fluctuations.

[0050] The theoretical dosage is calculated based on the nitrate nitrogen load and COD load entering the anoxic pool, and the nitrate nitrogen concentration control target value at the outlet of the anoxic pool is calculated. Then, the deviation between the nitrate nitrogen concentration at the outlet of the anoxic pool and the target value is compared. Through such feedback regulation, the system can avoid excessive addition of carbon sources. Excessive addition will not only increase operating costs, but may also have an adverse effect on subsequent treatment units. Therefore, accurate addition helps to reduce overall operating costs and optimize resource utilization. The feedback control mechanism makes the utilization of resources such as carbon sources more efficient, which helps to maximize the utilization of resources.

[0051] By setting the control target value of the nitrate nitrogen concentration at the outlet of the anoxic tank, the system can adjust the dosage of the carbon source in a targeted manner to ensure that the nitrate nitrogen concentration in the effluent is stable within a reasonable range. This precise control helps to reduce water quality fluctuations and improve the stability of effluent water quality. The setting of the control target value is usually based on national or local emission standards. By ensuring that the nitrate nitrogen concentration at the outlet of the anoxic tank does not exceed the control target value, the system can ensure that the final effluent meets the relevant emission standards and avoid the risk of exceeding the emission standard.

[0052] Furthermore, the control target value of the nitric nitrogen concentration at the outlet of the anoxic tank is determined as follows:

[0053]

[0054] S NO，sp =C in ×(1-R)

[0055] in: ——Nitrates nitrogen concentration in the effluent of the anoxic pool, mg / L;

[0056] S NO,sp ——Target value of nitrate nitrogen concentration at the outlet of anoxic pool, mg / L;

[0057] C in ——Nitrates nitrogen concentration in anoxic pool inlet, mg / L

[0058] R——Nitrates nitrogen removal rate.

[0059] Example 5: Reference Figure 1-Figure 3 , a precise carbon source dosing system for a sewage treatment plant, which is basically the same as Example 4, and further: in step S20, the feedforward control unit calculates the dosage based on the nitrate nitrogen concentration of the anoxic tank effluent, the COD concentration of the influent, the influent flow rate, the internal reflow flow rate, and the external reflow flow rate as follows:

[0060] q=0.02027×α×β1×(0.006×S COD -0.12)×Q

[0061] Where: q——dosing pump flow rate, L / h;

[0062] Q——water inlet flow, m 3 / h;

[0063] S COD ——Influent COD concentration, mg / L;

[0064] β1——Feedforward dosing coefficient (determined by experiment);

[0065] α——Safety factor, 1.05~1.20.

[0066] In the present invention, the sewage to be treated is introduced into the sewage treatment unit, and the sewage is processed in sequence through the pretreatment area, anaerobic tank, anoxic tank, aerobic tank, and secondary sedimentation tank, and then discharged after deep treatment and disinfection; the total nitrogen online monitor arranged at the water inlet and the water outlet transmits the values ​​of the total nitrogen concentration of the inlet and the total nitrogen concentration of the outlet to the main controller respectively; the COD meter arranged at the water inlet transmits the COD concentration value of the inlet to the main controller; the nitrate concentration meter arranged at the outlet of the anoxic tank transmits the detected nitrate nitrogen concentration to the main controller; the carbon source dosing point is the front end of the anoxic tank, the carbon source used is sodium acetate, the mass fraction of the effective component is 26.8%, and the feedforward dosing amount is based on the nitrate nitrogen concentration of the aerobic tank outlet, the COD concentration of the inlet, the inlet flow rate, the internal reflux flow rate, and the external reflux flow rate;

[0067] Among them, the value range of β1 is: 0~6;

[0068] In another embodiment, Figure 3 As shown, the control component includes a signal acquisition unit, a model calculation unit and a control signal output module; the signal acquisition unit collects signals of inlet flow rate, inlet total nitrogen meter monitoring value, inlet COD meter monitoring value, anoxic pool effluent nitric nitrogen meter monitoring value, aerobic pool effluent nitric nitrogen meter monitoring value, total effluent total nitrogen value, internal reflux flow rate, external reflux flow rate, dosing pump frequency, dosing pump stroke, storage tank liquid level, dosing pump flow rate and dosing room equipment operating status; wherein, the inlet flow meter signal is used to monitor the inlet flow rate, the internal reflux flow meter is used to monitor the internal reflux flow rate, and the external reflux flow meter is used to monitor the external reflux flow rate; the inlet COD meter signal, the anoxic pool effluent nitric nitrogen target value; the anoxic pool effluent nitric acid The salt concentration meter signal is used to adjust the carbon source dosage; the inlet total nitrogen and outlet total nitrogen signals are used to calibrate the nitrate concentration meter of the anoxic tank outlet; the dosing pump frequency and stroke signals are used to monitor the operating parameters of the dosing pump; the dosing pump flow signal is used to monitor the dosing flow; the liquid level signal of the storage tank is used to monitor the liquid level of the dosing tank; the dosing room equipment operation status signal is used to monitor whether the equipment is running. The model calculation unit includes a feedforward model and a feedback control model, and calculates the dosing pump amount based on the signal collected by the signal acquisition unit and the built-in model; the control signal output unit converts the dosing amount calculated by the model calculation unit into the dosing pump operating frequency, and then converts it into a control signal output to the PLC to control the operation of the dosing pump group;

[0069] It is further supplemented that the water inlet online flow meter is electrically connected to the control device; the feedforward nitrate nitrogen online instrument is electrically connected to the control device; the feedback nitrate nitrogen online instrument is electrically connected to the control device; the variable frequency dosing pump and the dosing flow meter are both electrically connected to the control device; the control device can adjust the frequency of the variable frequency dosing pump according to the water inlet volume signal fed back by the water inlet online flow meter and the nitrate nitrogen feedforward signal fed back by the feedforward nitrate nitrogen online instrument, as well as the nitrate nitrogen feedback signal fed back by the feedback nitrate nitrogen online instrument, and adjust the carbon source dosage to the sewage treatment system according to the carbon source dosage feedback signal of the dosing flow meter.

[0070] Example 6: Reference Figure 1-Figure 3 , a precise carbon source dosing system for a sewage treatment plant, which is basically the same as Example 5, and further: in step S20, the feedback control unit performs feedback adjustment based on the deviation of the nitric nitrogen concentration at the outlet of the anoxic tank and the target value:

[0071]

[0072] in: ——Nitrates nitrogen concentration in the effluent of the anoxic pool, mg / L;

[0073] S NO,sp ——Target value of nitrate nitrogen concentration at the outlet of anoxic pool, mg / L;

[0074] Q——water inlet flow, m3 / h;

[0075] Q1——Internal reflux flow, m 3 / h;

[0076] Q2——external return flow, m 3 / h;

[0077] β2——Feedback dosing coefficient (determined by experiments).

[0078] In actual operation, the inlet water quality is often affected by various factors and fluctuates. The above feedback adjustment mechanism enables the system to better cope with such fluctuations, maintain the stability of the outlet water quality, and improve the system stability. Through real-time feedback and precise adjustment, the stability of the system is significantly improved. Even in the face of large impact loads, the system can quickly recover and maintain stable operation.

[0079] Moreover, this precise dosing system based on feedforward and feedback is an important part of realizing smart water services. Through automated and intelligent control methods, it improves the efficiency and accuracy of sewage treatment. The system can collect and process a large amount of data in real time, providing managers with a scientific basis for decision-making. Through data analysis, it can continuously optimize the system's operating parameters and control strategies, further improving the overall performance of the system.

[0080] It is worth noting that if Figure 3 As shown, the initial dosage is calculated by feedforward control, that is, the theoretical dosage is calculated based on the influent COD and the nitrate nitrogen in the aerobic tank effluent; during the operation of the system, the dosage is adjusted using feedforward + feedback, and the feedback is used to adjust the dosage based on the deviation between the nitrate nitrogen concentration in the anoxic tank effluent and the target value;

[0081] Among them, the value range of β2 is: 0~5.

[0082] Example 7: Reference Figure 1-Figure 3 , a precise carbon source dosing system for a sewage treatment plant, is basically the same as Example 6, and further: in step S30, the dosing pump control unit adopts closed-loop automatic control technology for adjustment, and uses trial and error method to determine the PID parameters, and then adjusts the frequency of the dosing pump to stabilize the dosing pump flow rate near the set flow rate.

[0083] In the present invention, the dosing pump control adopts PID regulation, and the PID parameters are determined by trial and error method; firstly, the operation law of the dosing pump is roughly calculated by adjusting the dosing pump, and then the initial parameters are estimated according to the result, and then the frequency of each adjustment of the dosing pump and the flow meter reading feedback are observed, and the P, I, and D coefficients are increased or decreased accordingly, so that the control effect of the dosing pump tends to be stable;

[0084] The frequency of the dosing pump is adjusted to stabilize the flow rate of the dosing pump near the set flow rate. The PID adjustment method is adopted, and the PID parameters are determined by trial and error.

[0085] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the present invention can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A precise carbon source dosing system for a sewage treatment plant, comprising a sewage treatment unit, a dosing unit and a control unit, characterized in that: Also includes: The sewage treatment unit includes a biological pool and a secondary sedimentation tank, an external return pipe is arranged between the biological pool and the secondary sedimentation tank, and the secondary sedimentation tank is connected with the biological pool through the external return pipe, wherein the biological pool includes an anaerobic pool, an anoxic pool and an aerobic pool, an internal return pipe is arranged between the anoxic pool and the aerobic pool, and a nitrate concentration meter is arranged at the outlet of the anoxic pool, an internal return flow meter is arranged on the internal return pipe, and an external return flow meter is arranged on the external return pipe, an inlet flow meter, a COD meter and an inlet ammonia nitrogen meter are arranged at the water inlet of the sewage treatment unit, and an outlet total nitrogen meter is arranged at the total outlet of the sewage treatment unit.

2. A sewage treatment plant carbon source precise dosing system according to claim 1, characterized in that: A carbon source adding point is arranged at the front end of the anoxic pool, and the carbon source tank is connected to the carbon source adding point of the anoxic pool through a pipeline.

3. A sewage treatment plant carbon source precise dosing system according to claim 2, characterized in that: It includes a feedforward control unit and a feedback control unit, wherein the feedforward control unit includes a feedforward signal acquisition and calculation unit, the feedforward signal acquisition unit is used to acquire the signal required for feedforward control, and the feedforward built-in calculation unit is used to calculate the dosage according to the acquired feedforward signal; and the feedback control unit includes a feedback signal acquisition and calculation unit, the feedback signal acquisition unit is used to acquire the signal required for feedback control, and the feedback built-in calculation unit is used to calculate the dosage adjustment value according to the acquired feedback signal.

4. A sewage treatment plant carbon source precise dosing system according to claim 2, characterized in that: The carbon source liquid storage tank of the dosing unit is provided with a liquid level meter for measuring the liquid level of the carbon source in the carbon source liquid storage tank; a diaphragm metering pump is provided between the carbon source liquid storage tank and the carbon source addition point for conveying the carbon source; and an electric valve and a dosing flow meter are provided at the water outlet of the diaphragm metering pump for controlling the dosing flow.

5. A method for controlling a precise carbon source dosing system in a sewage treatment plant, characterized in that: The precise carbon source dosing system for a sewage treatment plant according to any one of claims 1 to 4 is used for control, and the specific steps include: S10, collecting signals of water inlet flow rate, water inlet total nitrogen meter monitoring value, water inlet COD meter monitoring value, nitrate concentration meter, total effluent total nitrogen value, internal reflux flow rate, external reflux flow rate, dosing pump frequency, drug storage tank liquid level, dosing pump flow rate and dosing room equipment operation status through the signal acquisition unit in the control unit; S20, using the feedforward control unit and the feedback control unit in the model calculation unit to calculate the signal collected in step S10 as the dosage or dosage adjustment value through the built-in calculation unit; S30, converting the calculated dosage or dosage adjustment value into the operating frequency of the dosing pump through the dosing pump control unit, and then converting it into a control signal output to the programmable logic controller to control the operation of the dosing pump to achieve accurate dosing.

6. A method for controlling a precise carbon source dosing system in a sewage treatment plant according to claim 5, characterized in that: The specific process of step S20 is: using the feedforward signal acquisition unit in the feedforward control unit to collect the signal required for feedforward control, the feedforward built-in calculation unit in the feedforward control unit calculates the dosage, using the feedback signal acquisition unit in the feedback control unit to collect the signal required for feedback control, and the feedback built-in calculation unit in the feedback control unit calculates the dosage adjustment value; wherein, an inlet flow meter and a COD meter are provided at the water inlet of the sewage treatment unit, and the theoretical dosage is calculated according to the nitrate nitrogen load and COD load entering the anoxic tank, and the nitrate nitrogen concentration control target value at the outlet of the anoxic tank is calculated; the feedback control includes providing a nitrate concentration meter at the outlet of the anoxic tank, and performing feedback adjustment according to the deviation of the nitrate nitrogen concentration at the outlet of the anoxic tank and the target value.

7. A method for controlling a precise carbon source dosing system in a sewage treatment plant according to claim 5, characterized in that: In step S20, the feedforward control unit calculates the dosage based on the nitrate nitrogen concentration of the anoxic tank effluent, the COD concentration of the inlet water, the inlet flow rate, the internal reflux flow rate, and the external reflux flow rate as follows: q=0.02027×α×β1×(0.006×S COD -0.12)×Q Where: q——dosing pump flow rate, L / h; Q——water inlet flow, m 3 / h; S COD ——Influent COD concentration, mg / L; β1——feedforward dosing coefficient; α——Safety factor, 1.05~1.

20.

8. A method for controlling a precise carbon source dosing system in a sewage treatment plant according to claim 5, characterized in that: In step S20, the feedback control unit performs feedback adjustment based on the deviation of the nitric nitrogen concentration at the outlet of the anoxic tank and the target value: in: ——Nitrates nitrogen concentration in the effluent of the anoxic pool, mg / L; ——Target value of nitrate nitrogen concentration at the outlet of anoxic pool, mg / L; Q——water inlet flow, m 3 / h; Q1——Internal reflux flow, m 3 / h; Q2——external return flow, m 3 / h; β2——Feedback dosing coefficient.

9. A method for controlling a precise carbon source dosing system in a sewage treatment plant according to claim 5, characterized in that: In step S30, the dosing pump control unit is adjusted by closed-loop automatic control technology, and the PID parameters are determined by trial and error, and then the frequency of the dosing pump is adjusted to stabilize the flow rate of the dosing pump near the set flow rate.

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