Sludge coagulation conditioning dosage prediction system based on mathematical regression model

Abstract

The invention discloses a sludge coagulation conditioning dosage prediction system based on a mathematical regression model, and belongs to the technical field of ecological environment protection. According to the method, the mathematical regression model is used for predicting the optimal coagulant dosage for sludge coagulation conditioning, the dosage is used as an independent variable, the ds / fc derivative parameters are used as dependent variables, the coagulation conditioning dosage and the electrochemical parameter ds / fc data of the corresponding sludge are used for simulation, and the optimal coagulant dosage is determined. According to the invention, sludge indexes can be monitored in real time, the dosing amount when the sludge dewatering performance is optimal can be predicted, automatic control of the dosing metering pump by the PC end can be realized, and sludge reduction can be assisted.

Description

Technical Field

[0001] The invention relates to a sludge coagulation conditioning dosage prediction system based on a mathematical regression model, belonging to the technical field of ecological environment protection. Background Art

[0002] With the acceleration of my country's urbanization process, cities, as the center of economic growth, have attracted a lot of investment and capital, the national economy has flourished, and the urban population has increased. Urban development has shifted from rapid expansion in quantity to high-quality development. Sludge, as a by-product of sewage treatment, has a significant positive correlation between its production and disposal volume and sewage discharge. Reduction, stabilization, harmlessness, and resource utilization are the basic principles of sludge treatment and disposal in my country. Among them, reduction is the basis for the other three transformations and the key to sludge treatment and disposal. Therefore, doing a good job in sludge reduction is crucial for my country's sludge treatment and disposal.

[0003] In the sludge treatment process, dehydration is an essential procedure to minimize the sludge volume, facilitate subsequent transportation, and reduce the space requirements during the disposal process. Due to the different sources of sewage in sewage treatment plants, the sewage properties are different, which leads to great differences in the properties of sludge distributed in different time and space, which is manifested in the physicochemical properties, rheological properties, structural properties and other aspects of the sludge. Ultimately, it is difficult to determine the dosage parameters to ensure the best dehydration effect.

[0004] In the context of the increasing amount of sludge generated, flocculation conditioning is the key to help reduce sludge. The problems of my country's current flocculation conditioning technology mainly remain in the difficulty of controlling the amount of flocculants added and cost-effectiveness. Therefore, the development of real-time monitoring of sludge indicators, predicting the dosage when the sludge dewatering performance reaches the best, and realizing automatic control of the dosing metering pump on the PC side is the development trend of sludge conditioning and dewatering technology. Summary of the invention

[0005] To solve the above problems, the present invention uses a mathematical regression model to predict the optimal coagulant dosage for sludge coagulation conditioning, takes the dosage as the independent variable and the ds / fc derived parameter as the dependent variable, and uses the coagulation conditioning dosage and the corresponding sludge electrochemical parameter ds / fc data for simulation to determine the optimal coagulant dosage.

[0006] In addition, the steps of the present invention to better realize the system function through a specific mathematical regression model are as follows:

[0007] (1) Use an electrochemical impedance spectroscopy instrument connected to a conductivity electrode probe to perform a frequency sweep test on the sludge to extract d s / f c Value, denoted as W 1 , detected W 1After that, the control system turns on the dosing pump, adds 1-10 mg / g of dry mud agent, and then turns off the dosing pump;

[0008] (2) Repeat the above operation n times, where n should be greater than 3, to obtain W 1 , W 2 , W 3 , W 4 ,……,W n , the data were smoothed using local polynomial regression (Lowess method);

[0009] In particular, n=3-5 is preferred;

[0010] At the same time, the Lowess method calculation formula is:

[0011]

[0012] Where yi' is the smoothed value of the ith data point; x i and i are the independent and dependent variable values ​​of the i-th data point, respectively; n is the total number of data points; K is the kernel function; b n is the bandwidth, usually chosen as a fraction of the data range, which controls the degree of smoothing of the local polynomial regression;

[0013] (3) Perform polynomial fitting on the smoothed data and calculate the derivative value of the polynomial within a certain range. When the derivative value is within a certain interval, find the derivative value and corresponding coordinate value that first appears in the interval:

[0014] ① If the derivative value is in the range of -0.001-0.001, the optimal coagulant dosage is the corresponding coordinate value of the derivative value that first appears in this interval;

[0015] ② If the derivative value is not in the range of -0.001-0.001, continue to look for the corresponding coordinate value of the derivative value that first appears in the range of -0.05-0.05. The corresponding coordinate value at this time is the optimal coagulant dosage.

[0016] The reagents include polyaluminium chloride, aluminium chloride and its hydrate, aluminium salt and its hydrate, ferric salt and its hydrate, ferric salt and its hydrate, and polyferric sulfate. The time interval between two consecutive frequency scans performed by the electrochemical impedance spectroscopy is 1.5-5 minutes. The sinusoidal voltage applied during the frequency scan of the electrochemical impedance spectroscopy is in the range of 1-1000 mV, and the scanning frequency range is 0.1 Hz-10 MHz. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Attached Figure 1 It is a flow chart of the present invention.

[0018] Attached Figure 2 It is the function graph obtained after polynomial fitting, where the ordinate is the ds / fc derivative parameter and the abscissa is the dosage.

[0019] Attached Figure 3 It is the overall schematic diagram of the present invention. In the figure: 1-PC terminal, 2-electrochemical impedance meter, 3-conductivity electrode probe, 4-stirring instrument, 5-dosing metering pump, 6-drug. Specific implementation plan

[0020] The present invention is described in detail below in conjunction with embodiments, but the drawings and embodiments involved are only exemplary and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the protection scope of the present invention.

[0021] Example 1:

[0022] The residual activated sludge was taken from the anaerobic / aerobic biological reaction process of a Beijing reclaimed water plant with a daily water treatment capacity of 1 million tons. The sludge concentration was 20.2 g / L. The dosing pump was controlled to add a certain amount of Fe in stages to the sludge. 2 (SO 4 ) 3 Coagulant liquid, use an electrochemical impedance meter connected to a conductivity electrode probe to perform a frequency sweep test on the sludge, and predict the optimal coagulant dosage based on the dynamic changes of ds / fc. Parallel experiments were carried out, and the optimal coagulant dosage predicted by the three systems was finally obtained, with an average value of 59.6 mg / g. The optimal dosage indicated by the traditional manual conditioning to evaluate the sludge dewatering performance is 65 mg / g, and the relative difference between the dosage average value predicted by the three systems is 8.31%. At the same time, the average value of the traditional offline indicator CST for feedback on the sludge dewatering performance was measured to be 32.1s, while the average value of the CST measured by traditional manual conditioning at the optimal dosage was 33.9s, with a relative difference of 5.31%. This shows that the sludge coagulation conditioning dosage prediction system can effectively and quickly condition the sludge to the optimal state of dehydration.

[0023] Example 2:

[0024] The residual activated sludge was taken from the anaerobic / aerobic biological reaction process of a Beijing reclaimed water plant with a daily water treatment capacity of 1 million tons. The sludge concentration was 14.1 g / L. The dosing pump was controlled to add a certain amount of Fe in stages to the sludge. 2 (SO 4 ) 3Coagulant liquid, use an electrochemical impedance meter connected to a conductivity electrode probe to perform a frequency sweep test on the sludge, and predict the optimal coagulant dosage based on the dynamic changes of ds / fc. Parallel experiments were carried out, and the optimal coagulant dosage predicted by the system was finally obtained three times, with an average value of 55.2 mg / g. The optimal dosage indicated by the traditional manual conditioning to evaluate the sludge dewatering performance is 60 mg / g, and the relative difference between the dosage and the average value of the three system predictions is 8%. At the same time, the average value of the traditional offline indicator CST for feedback on sludge dewatering performance was measured to be 12.9s, while the average value of CST measured by traditional manual conditioning at the optimal dosage was 13.8s, and the relative difference between it and the CST corresponding to the system prediction was 6.52%. This shows that the sludge coagulation conditioning dosage prediction system can effectively and quickly condition the sludge to the optimal state of dehydration.

Claims

1. A sludge coagulation conditioning dosage prediction system based on mathematical regression model, characterized in that: The mathematical regression model is used to predict the optimal coagulant dosage for sludge coagulation conditioning. The dosage is taken as the independent variable and the ds / fc derived parameter is taken as the dependent variable. The coagulation conditioning dosage and the corresponding sludge electrochemical parameter ds / fc data are simulated to determine the optimal coagulant dosage.

2. A sludge coagulation conditioning dosage prediction system based on a mathematical regression model, characterized in that: The system consists of six parts, including a PC terminal (1), an electrochemical impedance spectroscopy instrument (2), a conductivity electrode probe (3), a stirrer (4), a dosing metering pump (5), and a reagent (6).

3. The mathematical regression model according to claim 1, characterized in that: The models used include polynomial regression, linear regression, logistic regression, etc. The steps to predict the optimal dosage based on the polynomial regression model are as follows: (1) Use an electrochemical impedance spectroscopy instrument connected to a conductivity electrode probe to perform a frequency sweep test on the sludge to extract d s / f c Value, recorded as W1, after detecting W1, the control system turns on the dosing pump, adds 1-10 mg / g dry mud agent, and then turns off the dosing pump; (2) Repeat the above operation n times, where n should be greater than 3, to obtain W1, W2, W3, W4, ..., W n , use local polynomial regression (Lowess method) to smooth the data, the calculation formula is: Where yi' is the smoothed value of the ith data point; x i and i are the independent and dependent variable values ​​of the i-th data point, respectively; n is the total number of data points; K is the kernel function; b n is the bandwidth, usually chosen as a fraction of the data range, which controls the degree of smoothing of the local polynomial regression. (3) Perform polynomial fitting on the smoothed data and calculate the derivative value of the polynomial within a certain range. When the derivative value is within a certain interval, find the derivative value and corresponding coordinate value that first appears in the interval: ① If the derivative value is in the range of -0.001-0.001, the optimal coagulant dosage is the corresponding coordinate value of the derivative value that first appears in the interval; ② If the derivative value is not in the range of -0.001-0.001, continue to look for the corresponding coordinate value of the derivative value that first appears in the range of -0.05-0.

05. The corresponding coordinate value at this time is the optimal coagulant dosage.

4. A sludge coagulation conditioning dosage prediction system based on a mathematical regression model according to claim 1 or 2, characterized in that: The types of sludge include municipal surplus sludge, digested sludge, industrial wastewater sludge, river and lake bottom mud, pipeline sediment, fecal sludge, organic biogas residue, and pharmaceutical residue. The sludge concentration ranges from 1 to 100 g / L.

5. A sludge coagulation conditioning dosage prediction system based on a mathematical regression model according to claim 1 or 2, characterized in that: The medicaments include polyaluminium chloride, aluminium chloride and its hydrate, aluminium salt and its hydrate, ferric salt and its hydrate, ferric salt and its hydrate, ferrous salt and its hydrate, and polyferric sulfate.

6. A sludge coagulation conditioning dosage prediction system based on a mathematical regression model according to claim 1 or 2, characterized in that: The time interval between two consecutive frequency scans performed by the electrochemical impedance spectroscopy instrument is 1.5-5 minutes.

7. A sludge coagulation conditioning dosage prediction system based on a mathematical regression model according to claim 1 or 2, characterized in that: The sinusoidal voltage applied during the frequency scanning process of the electrochemical impedance spectroscopy is in the range of 1-1000 mV, and the scanning frequency is in the range of 0.1 Hz-10 MHz.

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