A precise phosphorus removal control method based on an efficient sedimentation tank with a magnetic medium

Abstract

The present invention discloses a precise phosphorus removal control method based on an efficient sedimentation tank with a magnetization medium, which relates to the technical field of sewage phosphorus removal. It includes four steps: real-time collection of influent parameters for the magnetic powder dosing tank, mixing tank, flocculation tank and efficient sedimentation tank, collaborative calculation of the chemical dosing amount through multi-variable dynamic modeling, chemical dosing, and feedback adjustment of effluent parameters; real-time monitoring of the influent flow rate, total phosphorus concentration and suspended solid concentration, combining the interaction formed by the sequential mixing reaction of magnetic powder, flocculant and coagulant aid with sewage, establishing a quadratic polynomial model of the total phosphorus removal rate, and dynamically calculating the theoretical dosing amounts of the three chemicals; monitoring and feedback of the total phosphorus concentration and suspended solid concentration of the effluent at the effluent end, and dynamically adjusting the chemical dosing amount accordingly; realizing precise dosing of the phosphorus removal chemicals, improving the phosphorus removal effect, reducing the operating cost and enhancing the automation level; solving the problems that the existing sewage sedimentation phosphorus removal process has difficulty in precisely controlling the chemical dosing amount and low automation degree.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage phosphorus removal, and particularly relates to a precise phosphorus removal control method based on an efficient sedimentation tank with magnetic medium addition. Background Art

[0002] In the field of sewage treatment, the effective removal of phosphorus is of great significance for preventing water eutrophication and ensuring ecological safety.

[0003] At present, the methods for sewage treatment plants to remove phosphorus from sewage mainly include biological phosphorus removal and chemical phosphorus removal.

[0004] Among them, biological phosphorus removal reduces the phosphorus content in sewage through the enrichment of polyphosphate-accumulating organisms, which has the advantages of economy and environmental protection. However, in actual operation, it is difficult to stably achieve the discharge standard that the total phosphorus (TP) data of the effluent is lower than 0.5 mg / L solely relying on biological phosphorus removal. Therefore, usually, after the biological phosphorus removal treatment process, a chemical phosphorus removal treatment process is supplemented to ensure that the effluent quality at the end meets the standard.

[0005] Chemical phosphorus removal mainly realizes the removal of phosphorus by adding agents such as aluminum salts or iron salts to sewage to form insoluble precipitates with dissolved phosphorus in water.

[0006] In recent years, the development of the magnetic coagulation sedimentation technology has provided a new solution for the advanced treatment of sewage. In this technology, magnetic media are introduced during the processes of coagulation, flocculation, and sedimentation, making them the core particles of the flocs, enhancing the floc density, accelerating the sedimentation speed, and significantly improving the sedimentation efficiency and hydraulic load of the sedimentation tank. The magnetic coagulation sedimentation technology has been applied to the advanced treatment unit of sewage treatment plants and used in conjunction with phosphorus removal agents to further reduce the TP data and suspended solid concentration of the effluent.

[0007] However, currently, the control of the dosage of phosphorus removal agents in magnetic coagulation sedimentation tanks mostly relies on the empirical method, that is, operators infer the dosage of phosphorus removal agents based on the effluent situation of the front-end process and the TP data at the discharge port. This method has problems such as strong subjectivity and response lag, and it is difficult to achieve precise control.

[0008] Therefore, some sewage treatment plants introduce an automatic dosing system to estimate the dosage of agents based on the TP data of the effluent and the influent flow rate, and make corrections according to the commissioning experience. Due to the data lag in on-line TP detection and the lack of full consideration of the interaction between agents, the system often needs to overdose phosphorus removal agents and magnetic media to ensure that the effluent quality at the end meets the standard, but this operation directly increases the process cost of sewage sedimentation and phosphorus removal.

[0009] In addition, most existing automatic chemical dosing systems rely on a single parameter, such as the TP concentration, as the control basis, lacking the collaborative consideration of multiple parameters of the sewage, and it is difficult to cope with the impact brought by the fluctuation of the influent water quality, making it impossible to accurately control the dosing amounts of phosphorus removal agents and magnetic media. For example, the BOD / TP ratio in the sewage has a significant impact on the biological phosphorus removal effect. When this ratio is imbalanced, the biological phosphorus removal efficiency decreases, and it is necessary to compensate by accurately dosing carbon sources or adjusting the dosing amount of chemical phosphorus removal agents; however, the existing automatic chemical dosing systems have limited control capabilities in this regard and are difficult to achieve dynamic adjustment.

[0010] The existing technology has multiple technical problems:

[0011] 1. The lag of data feedback leads to insufficient accuracy in dosing amount control: The chemical dosing control relies on experience or the lagging online detection data of the effluent at the back end, and it is difficult to achieve real-time and accurate adjustment of the chemical dosing link at the front end;

[0012] 2. The coupling effect of multiple variables is not effectively considered: The existing control strategies do not systematically quantify the interaction effects among multiple parameters such as the dosing amount of magnetic media, the type of chemical agents, and hydraulic conditions, and it is impossible to achieve the collaborative optimization of multiple factors, making it difficult to cope with the impact brought by the fluctuation of the influent water quality;

[0013] 3. The excessive dosing of chemical agents leads to an increase in operating costs: The interaction between chemical agents is not fully considered, and there is an excessive dosing phenomenon. Although the conservative excessive dosing strategy can ensure the compliance of the effluent, it significantly increases the chemical agent consumption, magnetic media loss, and sludge disposal costs, restricting the process economy and increasing the operating costs;

[0014] 4. The degree of automation is low: The automation degree of the system is not high, and the operation is complex, increasing the difficulty of operation and management.

[0015] In summary, it is found that the existing technology has at least the following technical problems:

[0016] The existing sewage sedimentation and phosphorus removal process has technical problems such as low accuracy in dosing amount control of chemical agents, inability to achieve the collaborative optimization of multiple parameters such as the dosing amount of magnetic media, the type of chemical agents, and hydraulic conditions, and excessive dosing of chemical agents caused by low automation degree. Summary of the Invention

[0017] The purpose of the present invention is to provide a precise phosphorus removal control method based on a high-efficiency sedimentation tank with magnetic media addition to solve the technical problems of the existing sewage sedimentation and phosphorus removal process, such as low accuracy in dosing amount control of chemical agents, inability to achieve the collaborative optimization of multiple parameters such as the dosing amount of magnetic media, the type of chemical agents, and hydraulic conditions, and excessive dosing of chemical agents caused by low automation degree.

[0018] The many technical effects that can be produced by the preferred technical solutions provided by the present invention are described in detail below.

[0019] To solve the above technical problems, the present invention provides the following technical solutions:

[0020] The present invention provides a precise phosphorus removal control method based on a magnetic medium high-efficiency sedimentation tank, which includes successively arranging a magnetic powder dosing tank, a mixing tank, a flocculation tank, and a high-efficiency sedimentation tank along the direction from sewage inlet to outlet, and a controller is arranged in the sedimentation phosphorus removal process machine room; during the precise phosphorus removal process, the controller collects data, calculates the dosing amount of chemicals according to the precise phosphorus removal steps, and controls the dosing of magnetic powder, flocculant, and coagulant aid to the magnetic powder dosing tank, mixing tank, and flocculation tank in a way of dynamically limiting the dosing amount, so as to precisely control the dosing amounts of magnetic powder, flocculant, and coagulant aid to achieve precise phosphorus removal;

[0021] Among them, the precise phosphorus removal steps are as follows: S1. Real-time collection of influent parameters: An influent flowmeter, an influent total phosphorus concentration analyzer, and an influent online suspended solids concentration analyzer are arranged at the sewage inlet end of the magnetic powder dosing tank to respectively and real-time collect the influent flow rate, influent total phosphorus concentration, and influent suspended solids concentration at the inlet end;

[0022] S2. Multivariable dynamic modeling and collaborative calculation of chemical dosing amounts: Based on the interaction relationship of the magnetic powder dosing amount A, the flocculant dosing amount B, and the coagulant aid dosing amount C, a quadratic polynomial model of the total phosphorus removal rate is established; according to the influent flow rate, influent total phosphorus concentration, and the preset effluent total phosphorus concentration limit value, the controller solves the quadratic polynomial model of the total phosphorus removal rate to dynamically calculate the theoretical dosing amounts A0, B0, and C0 of magnetic powder, flocculant, and coagulant aid;

[0023] S3. Chemical dosing: The magnetic powder is dosed into the magnetic powder dosing tank according to A0, the flocculant is dosed into the mixing tank according to B0, and the coagulant aid is dosed into the flocculation tank according to C0. The chemicals are successively mixed with the flowing sewage in each tank, and flocculation is completed in the flocculation tank, and finally precipitation is completed in the high-efficiency sedimentation tank;

[0024] S4. Feedback regulation of effluent parameters: An effluent flowmeter, an effluent total phosphorus concentration analyzer, and an effluent online suspended solids concentration analyzer are arranged at the effluent end of the high-efficiency sedimentation tank to real-time monitor the effluent total phosphorus concentration and effluent suspended solids concentration at the effluent end; the controller compares the measured effluent total phosphorus concentration with the effluent total phosphorus concentration limit value to judge whether the effluent is qualified: if the effluent total phosphorus concentration > the effluent total phosphorus concentration limit value, it is judged that the effluent is unqualified, and then the effluent total phosphorus fluctuation value is obtained according to the deviation value between the effluent total phosphorus concentration and the effluent total phosphorus concentration limit value, and the dosing amounts of A, B, and C are dynamically corrected with a preset adjustment range; if the effluent total phosphorus concentration ≤ the effluent total phosphorus concentration limit value, it is judged that the effluent is qualified, and the fluctuation range of the effluent total phosphorus fluctuation value is lower than the preset effluent total phosphorus fluctuation value threshold, then the current chemical dosing amount is maintained.

[0025] In one embodiment, the quadratic polynomial model of the total phosphorus removal rate is: Total phosphorus removal rate = a + b×B - c×C + d×A - e×B×C + f×B×A + g×C×A - h×B 2 + i×C 2 - j×A 2 ;

[0026] In the formula, a is the safety coefficient, and b to j are the interaction influence coefficients of magnetic powder, flocculant, and coagulant aid.

[0027] In one embodiment, the value of the safety coefficient a is 8.80 - 8.95, which is set by the maximum value of the measured error of the recorded historical influent flow rate and total phosphorus concentration, and is used to compensate for the prediction error of the total phosphorus removal rate caused by the deviation of influent data collection.

[0028] In one embodiment, the coefficients b to j of the quadratic polynomial model of the total phosphorus removal rate are determined by orthogonal experiments and multiple regression analysis, including: within the range of influent total phosphorus concentration of 1 - 4 mg / L, multiple groups of experiments are carried out by changing the dosing amount combinations of A, B, and C, the total phosphorus removal rate data are recorded, and the values of each coefficient b to j are obtained by least squares fitting.

[0029] In one embodiment, in step S4, the adjustment amplitude has a piecewise linear relationship with the effluent total phosphorus fluctuation value: when the effluent total phosphorus fluctuation value ≤ 0.1 mg / L, the adjustment amplitude is 2 - 5% of the theoretical dosing amount; when 0.1 mg / L < effluent total phosphorus fluctuation value ≤ 0.3 mg / L, the adjustment amplitude is 5 - 10% of the theoretical dosing amount; when the effluent total phosphorus fluctuation value > 0.3 mg / L, the adjustment amplitude is 10 - 15% of the theoretical dosing amount.

[0030] In one embodiment, in step S3, the stirring intensities of the magnetic powder dosing tank, mixing tank, and flocculation tank are linked to the dosing amounts of A, B, and C respectively: the stirring speed of the magnetic powder dosing tank is positively correlated with A, the stirring speed of the mixing tank is positively correlated with B, and the stirring speed of the flocculation tank is negatively correlated with C.

[0031] In one embodiment, in step S2, the effluent total phosphorus concentration limit value is 0.3 - 0.5 mg / L, and the controller automatically selects a preset chemical dosing priority strategy according to the difference between the influent total phosphorus concentration and the effluent total phosphorus concentration limit value: when the influent total phosphorus concentration > 3 mg / L, the dosing proportion of the flocculant B is preferentially increased; when 1 mg / L ≤ influent total phosphorus concentration ≤ 3 mg / L, the synergistic dosing amounts of the magnetic powder A and the coagulant aid C are preferentially optimized.

[0032] In one embodiment, the influent suspended solids concentration analyzer and the effluent suspended solids concentration analyzer are used to obtain the influent suspended solids concentration and the effluent suspended solids concentration, which are used to correct the interaction coefficients g and i in the quadratic polynomial model of the total phosphorus removal rate in step S2: when the influent suspended solids concentration > 50 mg / L, the coefficient g is increased by 10 - 20%, and the coefficient i is decreased by 5 - 10%; when the influent suspended solids concentration ≤ 50 mg / L, the coefficients g and i maintain the reference values.

[0033] In one embodiment, it further includes step S5, optimizing the magnetic powder recovery efficiency: the controller dynamically adjusts the dosage of A according to the magnetic powder content value of the bottom sludge of the high-efficiency sedimentation tank obtained, so that the mass ratio of the recovered magnetic powder to the newly added magnetic powder is controlled within 1:0.3 - 1:0.8.

[0034] In one embodiment, a pH sensor and a temperature sensor are further arranged in the high-efficiency sedimentation tank; in step S2, the controller accesses the pH sensor and the temperature sensor arranged in the high-efficiency sedimentation tank, and according to the pH value and water temperature data of the high-efficiency sedimentation tank obtained in real time; when it is detected that the pH value exceeds the range of 6.5 - 8.0, the coefficients e and h in the quadratic polynomial model of the total phosphorus removal rate are dynamically corrected according to the pH deviation value: if the pH deviation value > 0.5, the coefficient e is increased by 10 - 15%, and the coefficient h is decreased by 5 - 10%; if the pH deviation value < -0.5, the coefficient e is decreased by 10 - 15%, and the coefficient h is increased by 5 - 10%; at the same time, when the water temperature is lower than 10 °C, the coefficients b and d are respectively increased by 20 - 30% to compensate for the decrease in the flocculation reaction rate caused by low temperature.

[0035] The beneficial effects of the present invention are as follows:

[0036] The present technical solution provides a precise phosphorus removal control method based on a high-efficiency sedimentation tank with a magnetic medium, and has advantages in multiple aspects such as the control accuracy of chemical agent dosing, the coordinated optimization of multiple water quality parameters for chemical agent dosing, the reduction of operating costs, and the improvement of the automation level of the sewage treatment process, thereby effectively solving the technical problems existing in the existing sewage sedimentation and phosphorus removal processes, such as low control accuracy of chemical agent dosage, inability to achieve multi-parameter coordinated optimization of magnetic medium dosage, chemical agent types, and hydraulic conditions, and excessive chemical agent dosing caused by low automation level:

[0037] (1) Improve the control accuracy of chemical agent dosing: By arranging an influent flow meter, an influent total phosphorus concentration analyzer, and an influent on-line suspended solids concentration analyzer at the sewage inlet end of the magnetic powder dosing tank on the sewage inlet side, the influent flow rate, influent total phosphorus concentration, and influent suspended solids concentration are collected in real time. Combining with the quadratic polynomial model of the total phosphorus removal rate based on multi-variable dynamic modeling, the theoretical dosing amounts of magnetic powder, flocculant, and coagulant aid are accurately calculated, effectively avoiding the problems of dosing lag and inaccuracy caused by estimating the dosing amount by the traditional empirical method, and improving the accuracy and real-time performance of chemical agent dosing control.

[0038] (2) Achieve multi-parameter collaborative optimization control: Construct a quadratic polynomial model of the total phosphorus removal rate based on the interaction of magnetic powder, flocculant, and coagulant aid. Comprehensively consider the non-linear coupling relationship between different chemicals and hydraulic conditions, so that the dosage of chemicals can dynamically respond to the fluctuation of influent water quality, realize multi-variable collaborative regulation and optimization, improve the stability and reliability of phosphorus removal efficiency, and avoid excessive dosing to control the phosphorus removal cost.

[0039] (3) Reduce operating costs: Through precise calculation and dynamic adjustment mechanism, effectively avoid the phenomenon of excessive dosing of chemicals commonly existing in traditional automatic dosing systems, reduce the usage of chemicals and magnetic powder, reduce the sludge production and treatment costs, and improve the economy of the entire phosphorus removal process.

[0040] (4) Improve the automation level of the magnetic medium high-efficiency sedimentation tank system: Through the influent flowmeter, influent total phosphorus concentration analyzer, influent online suspended solid concentration analyzer, effluent flowmeter, effluent total phosphorus concentration analyzer, and effluent online suspended solid concentration analyzer, conduct multi-point online monitoring of the sewage phosphorus removal process, and form a closed-loop feedback control system with the controller. Combining the preset effluent limit value and fluctuation threshold, dynamically correct the chemical dosage, significantly improve the automation and intelligence level of the system, reduce the frequency of manual intervention, simplify the operation process, and enhance the convenience and efficiency of operation management.

[0041] In summary, the precise phosphorus removal control method provided in this technical solution has significantly improved in terms of phosphorus removal effect, operating cost control, and process automation control compared with the existing sewage sedimentation phosphorus removal technology, and is applicable to the construction of an automatic control system for the advanced phosphorus removal process in sewage treatment plants. Brief Description of the Drawings

[0042] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for implementation will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0043] Figure 1 It is a schematic structural diagram of the magnetic medium high-efficiency sedimentation tank of the present invention.

[0044] Among them, the reference numerals are as follows:

[0045] 1. Magnetic powder dosing tank; 11. Influent flowmeter; 12. Influent total phosphorus concentration analyzer; 13. Influent online suspended solid concentration analyzer;

[0046] 2. Mixing tank;

[0047] 3. Flocculation tank;

[0048] 4. High - efficiency sedimentation tank; 41. Effluent flowmeter; 42. Effluent total phosphorus concentration analyzer; 43. Effluent online suspended solid concentration analyzer;

[0049] 5. Controller;

[0050] 6. pH sensor;

[0051] 7. Temperature sensor;

[0052] 8. Magnetic powder content detection device. Specific implementation manners

[0053] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0054] A precise phosphorus removal control method based on a high - efficiency sedimentation tank with magnetic medium addition is provided in the specific implementation manners. It is applicable to the advanced phosphorus removal process in the sewage treatment field. Through four steps of real - time collection of influent parameters, multi - variable dynamic modeling and collaborative calculation of chemical dosing amounts, chemical dosing, and feedback regulation of effluent parameters for the magnetic powder dosing tank 1, mixing tank 2, flocculation tank 3, and high - efficiency sedimentation tank 4; real - time monitoring of the influent flow rate, total phosphorus concentration, and suspended solid concentration, combined with the interaction formed by the sequential mixing of magnetic powder, flocculant, and coagulant aid with sewage, establishing a quadratic polynomial model of the total phosphorus removal rate, dynamically calculating the theoretical dosing amounts of the three chemicals; monitoring and feedback of the total phosphorus concentration and suspended solid concentration of the effluent at the effluent end, and dynamically adjusting the chemical dosing amounts accordingly; realizing precise dosing of magnetic powder, flocculant, and coagulant aid for phosphorus removal, improving the phosphorus removal effect, reducing the operating cost, and enhancing the automation level; effectively solving the technical problems existing in the existing sewage sedimentation and phosphorus removal processes, such as low control accuracy of chemical dosing amounts, inability to achieve multi - parameter collaborative optimization of magnetic medium dosing amounts, chemical types, and hydraulic conditions, and excessive chemical dosing caused by low automation level.

[0055] The first embodiment of the precise phosphorus removal control method based on a high - efficiency sedimentation tank with magnetic medium addition is as Figure 1 shown. It includes a magnetic powder dosing tank 1, a mixing tank 2, a flocculation tank 3, and a high - efficiency sedimentation tank 4 arranged in sequence along the direction of sewage influent to effluent, and a controller 5 is provided in the sedimentation and phosphorus removal process machine room; during the precise phosphorus removal process, the controller 5 collects data, calculates the chemical dosing amounts according to the precise phosphorus removal steps, and controls the dosing of magnetic powder, flocculant, and coagulant aid to the magnetic powder dosing tank 1, mixing tank 2, and flocculation tank 3 in a way of dynamically limiting the dosing amounts, so as to precisely control the dosing amounts of magnetic powder, flocculant, and coagulant aid to achieve precise phosphorus removal;

[0056] Among them, the precise phosphorus removal steps are as follows: S1. Real-time collection of influent parameters: An influent flowmeter 11, an influent total phosphorus concentration analyzer 12, and an influent online suspended solid concentration analyzer 13 are set at the sewage inlet end of the magnetic powder dosing tank 1 to respectively collect the influent flow rate, the influent total phosphorus concentration, and the influent suspended solid concentration at the inlet end in real time;

[0057] S2. Multivariable dynamic modeling for collaborative calculation of chemical dosing amounts: Based on the interaction relationship among the magnetic powder dosing amount A, the flocculant dosing amount B, and the coagulant aid dosing amount C, establish a quadratic polynomial model for the total phosphorus removal rate;

[0058] According to the influent flow rate, the influent total phosphorus concentration, and the preset effluent total phosphorus concentration limit value, solve the quadratic polynomial model of the total phosphorus removal rate through the controller 5 to dynamically calculate the theoretical dosing amounts A0, B0, and C0 of the magnetic powder, the flocculant, and the coagulant aid;

[0059] S3. Chemical dosing: Add the magnetic powder to the magnetic powder dosing tank 1 according to A0, add the flocculant to the mixing tank 2 according to B0, and add the coagulant aid to the flocculation tank 3 according to C0. The chemicals are sequentially mixed with the flowing sewage in each tank, and flocculation is completed in the flocculation tank. Finally, precipitation is completed in the high-efficiency sedimentation tank 4;

[0060] S4. Feedback regulation of effluent parameters: An effluent flowmeter 41, an effluent total phosphorus concentration analyzer 42, and an effluent online suspended solid concentration analyzer 43 are set at the effluent end of the high-efficiency sedimentation tank 4 to monitor the effluent total phosphorus concentration and the effluent suspended solid concentration at the effluent end in real time;

[0061] The controller 5 compares the measured effluent total phosphorus concentration with the effluent total phosphorus concentration limit value to judge whether the effluent is qualified:

[0062] If the effluent total phosphorus concentration > the effluent total phosphorus concentration limit value, it is judged that the effluent is unqualified. Then, according to the deviation value between the effluent total phosphorus concentration and the effluent total phosphorus concentration limit value, obtain the effluent total phosphorus fluctuation value, and dynamically correct the dosing amounts of A, B, and C at a preset adjustment amplitude;

[0063] If the effluent total phosphorus concentration ≤ the effluent total phosphorus concentration limit value, it is judged that the effluent is qualified, and the fluctuation amplitude of the effluent total phosphorus fluctuation value is lower than the preset effluent total phosphorus fluctuation value threshold, then maintain the current chemical dosing amount.

[0064] Step S5. Optimization of magnetic powder recovery efficiency: According to the magnetic powder content value of the bottom sludge in the high-efficiency sedimentation tank 4, dynamically adjust the dosing amount of A to control the mass ratio of the recovered magnetic powder to the newly added magnetic powder within 1:0.3 to 1:0.8.

[0065] During application, as Figure 1 shown, a magnetic powder content detection device 8 is set in the high-efficiency sedimentation tank 4 to detect the magnetic powder content value of the bottom sludge in the high-efficiency sedimentation tank.

[0066] For the above step S4, regarding the total phosphorus concentration of the effluent and the limit value of the total phosphorus concentration of the effluent, the limit value of the total phosphorus concentration of the effluent is the maximum total phosphorus limit value for the effluent parameters required at the effluent end of the high-efficiency sedimentation tank 4 to achieve qualified total phosphorus concentration. When the total phosphorus concentration of the effluent does not exceed the limit value of the total phosphorus concentration of the effluent, the effluent is qualified.

[0067] Among them, the fluctuation range of the total phosphorus fluctuation value in step S4 and the preset threshold value of the total phosphorus fluctuation value of the effluent are used to judge the system stability of the phosphorus removal process. The preset threshold value of the total phosphorus fluctuation value of the effluent can be specifically set according to the required stable state amplitude of the actual operating phosphorus removal process.

[0068] With the precise phosphorus removal steps in cooperation with the magnetic powder dosing tank 1, mixing tank 2, flocculation tank 3 and high-efficiency sedimentation tank 4, and the influent flowmeter 11, influent total phosphorus concentration analyzer 12, influent online suspended solid concentration analyzer 13 set at the sewage influent end, and the effluent flowmeter 41, effluent total phosphorus concentration analyzer 42, effluent online suspended solid concentration analyzer 43 set at the effluent end, the control process achieved is as follows: Refer to Figure 1 and the precise phosphorus removal steps;

[0069] First, the controller 5 collects the influent flow rate, influent total phosphorus concentration and influent suspended solid concentration data collected at the sewage influent end before the magnetic powder dosing tank according to step S1, and then inputs the collected influent data into the quadratic polynomial model of the total phosphorus removal rate established in advance in step S2 to dynamically calculate the theoretical dosing amounts of magnetic powder, flocculant and coagulant aid.

[0070] Then enter step S3. In the first-round chemical dosing, the corresponding chemicals are dosed into each magnetic powder dosing tank 1, mixing tank 2 and flocculation tank 3 in sequence according to the calculated theoretical dosing amounts of magnetic powder, flocculant and coagulant aid and are dosed within the limit of the theoretical dosing amount. The chemicals are mixed and superimposed with the flowing sewage in the magnetic powder dosing tank 1, mixing tank 2 and flocculation tank 3 in sequence, and the processes of flocculation in the flocculation tank 3 and sedimentation in the high-efficiency sedimentation tank 4 are completed, and then the effluent is achieved at the effluent end of the high-efficiency sedimentation tank 4.

[0071] Then, enter step S4. By monitoring the water quality at the effluent end of the high-efficiency sedimentation tank 4, the effluent total phosphorus concentration and effluent suspended solid concentration data are obtained. The controller 5 compares the measured effluent total phosphorus concentration with the limit value of the effluent total phosphorus concentration, and according to the preset rules, corrects or maintains the dosing amounts of magnetic powder, flocculant and coagulant aid, and takes the dosing amount data corrected or maintained in step S4 as the priority and directly enters step S3 to control the dosing amount of the next-round chemical dosing.

[0072] When there are significant changes in the influent flow rate, influent total phosphorus concentration, and influent suspended solid concentration measured at the sewage inlet end of the magnetic powder dosing tank 1, and the controller 5 determines that the current chemical dosing amount data can no longer meet the requirement for precise phosphorus removal, it is necessary to re-enter step S2 with the measured data of the influent flow rate, influent total phosphorus concentration, and influent suspended solid concentration at the sewage inlet end of the magnetic powder dosing tank 1 to recalculate the new theoretical chemical dosing amount, and then sequentially enter steps S3 and S4 for implementation in sequence;

[0073] Among them, when the controller 5 implements steps S1 to S4, it also synchronously collects the magnetic powder content value of the bottom sludge of the high-efficiency sedimentation tank 4 through the magnetic powder content detection device 8, and controls the ratio of the magnetic powder recovered in the high-efficiency sedimentation tank 4 and the newly added magnetic powder in the magnetic powder dosing tank 1 according to the collected magnetic powder content value data, that is, the mass ratio of the recovered magnetic powder to the newly added magnetic powder is controlled within 1:0.3 to 1:0.8, and directly finally corrects the magnetic powder dosing amount in step S3.

[0074] The specific setting of the above quadratic polynomial model for total phosphorus removal rate is: Total phosphorus removal rate = a + b×B - c×C + d×A - e×B×C + f×B×A + g×C×A - h×B 2 +i×C 2 -j×A 2 ;

[0075] In the formula, a is the safety factor, and b to j are the interaction influence coefficients of magnetic powder, flocculant, and coagulant aid.

[0076] For the safety factor a: The value range of a is 8.80 to 8.95; the safety factor a is set based on the maximum value of the historical influent flow rate and total phosphorus concentration measurement errors recorded, and is used to compensate for the acquisition deviation of the influent flow rate, influent total phosphorus concentration, or influent suspended solid concentration of the influent data, so as to avoid prediction errors in the total phosphorus removal rate.

[0077] For the interaction influence coefficients b to j: In the multi-variable dynamic modeling collaborative calculation of chemical dosing amount in step S2, the coefficients b to j are determined through orthogonal experiments and multiple regression analysis, including: within the range of influent total phosphorus concentration of 1 to 4 mg / L, multiple groups of experiments are carried out by changing the dosing amount combinations of A, B, and C, the total phosphorus removal rate data are recorded, and the numerical values of the b to j coefficients are obtained by least squares fitting.

[0078] The interaction relationship and interaction formed by the mutual influence among magnetic powder, flocculant, and coagulant aid:

[0079] (1)The interaction between magnetic powder and flocculant

[0080] Positive impacts: Flocculants (such as PAC and PAM) wrap suspended solids on the surface of magnetic powder through charge neutralization and bridging effects, forming high-density magnetic flocs and enhancing the sedimentation rate.

[0081] Potential problems:

[0082] Excessive flocculant covering magnetic powder: If the dosage of flocculant is excessive, it may completely cover the surface of magnetic powder, preventing the direct adsorption of pollutants (suspended solids) by magnetic powder and reducing the magnetic recovery rate;

[0083] Charge conflict: The surface of magnetic powder is positively charged, while flocculants are anionic (such as some PAMs), which may lead to a decrease in adsorption efficiency due to charge repulsion.

[0084] (2) Interaction between flocculant and coagulant aid

[0085] Synergistic effect: The coagulant aid enhances the network structure formed by the flocculant by filling the gaps in the flocs, making the flocs denser.

[0086] Negative impacts:

[0087] Incorrect dosing sequence: If the coagulant aid is dosed first, it may preferentially adsorb suspended particles, occupying the active sites of the flocculant and weakening the charge neutralization effect;

[0088] Chemical incompatibility: The coagulant aid may change the pH of the water body, causing the hydrolysis of the flocculant (such as PAM) and rendering it ineffective.

[0089] (3) Interaction between magnetic powder and coagulant aid

[0090] Adsorption competition: Magnetic powder may adsorb the active components in the coagulant aid, resulting in a decrease in the effective concentration of the coagulant aid and the need for additional dosing of the coagulant aid.

[0091] Therefore, since the magnetic powder, flocculant, and coagulant aid are successively mixed with the sewage and the superimposed reactions form interaction effects, synchronously restricting the treatment effect of sewage and the dosing amounts of the magnetic powder, flocculant, and coagulant aid, the establishment of the quadratic polynomial model for the total phosphorus removal rate in step S2 needs to follow the interaction relationship among the magnetic powder, flocculant, and coagulant aid.

[0092] In step S2, the limit value of the total phosphorus concentration in the effluent is 0.3 - 0.5 mg / L, and the controller 5 automatically selects a preset chemical dosing priority strategy according to the difference between the total phosphorus concentration in the influent and the limit value of the total phosphorus concentration in the effluent: when the total phosphorus concentration in the influent > 3 mg / L, the dosing ratio of flocculant B is preferentially increased; when 1 mg / L ≤ the total phosphorus concentration in the influent ≤ 3 mg / L, the synergistic dosing amounts of magnetic powder A and coagulant aid C are preferentially optimized.

[0093] As one of the optional implementation manners:

[0094] Regarding the assistance of the stirring intensity in each pool during the dosing of the agent in step S3 above to the reaction of the agent, in order to make the reaction effects of magnetic powder, flocculant, and coagulant aid in the pool better, achieve the expected effects in all links of sewage phosphorus removal, and save the dosing amounts of magnetic powder, flocculant, and coagulant aid.

[0095] During application, in step S3, the stirring intensities of the magnetic powder dosing tank 1, mixing tank 2, and flocculation tank 3 are controlled in linkage with the dosing amounts of A, B, and C respectively: the stirring speed of the magnetic powder dosing tank 1 is positively correlated with A, the stirring speed of the mixing tank 2 is positively correlated with B, and the stirring speed of the flocculation tank 3 is negatively correlated with C.

[0096] Regarding the specific setting of the adjustment range in step S4 above, in the feedback adjustment of the effluent parameters in step S4, the adjustment range has a piecewise linear relationship with the fluctuation value of the total phosphorus in the effluent: when the fluctuation value of the total phosphorus in the effluent ≤ 0.1 mg / L, the adjustment range is 2 - 5% of the theoretical dosing amount; when 0.1 mg / L < the fluctuation value of the total phosphorus in the effluent ≤ 0.3 mg / L, the adjustment range is 5 - 10% of the theoretical dosing amount; when the fluctuation value of the total phosphorus in the effluent > 0.3 mg / L, the adjustment range is 10 - 15% of the theoretical dosing amount.

[0097] During application, the adjustment range is the single - correction range for dynamically adjusting the dosing amount of the agent according to the fluctuation value of the total phosphorus in the effluent. Through the piecewise proportional control strategy, precise and progressive adjustment of the dosing amount of the agent is achieved, avoiding water quality fluctuations caused by over - dosing or under - dosing.

[0098] Among them: when the fluctuation value of the total phosphorus in the effluent is small, through small - step progressive adjustment, it prevents the drastic fluctuation of the total phosphorus concentration in the effluent caused by sudden dosing, playing a role in suppressing overshoot; when the fluctuation value of the total phosphorus in the effluent is large, through large - step adjustment, the adjustment time of the dosing amount of the agent is shortened to achieve rapid response; by judging the fluctuation value of the total phosphorus in the effluent and selecting different adjustment strategies, it can avoid blind over - dosing, reduce the waste of the agent, achieve energy conservation and consumption reduction in the dosing of the agent, and reduce the cost of the sewage phosphorus removal process.

[0099] Regarding the correction of the interaction influence coefficients g and i in the quadratic polynomial model of the total phosphorus removal rate in step S2 above:

[0100] As Figure 1 shown, according to the influent suspended solid concentration data measured by the influent online suspended solid concentration analyzer 13 and the effluent suspended solid concentration data measured by the effluent online suspended solid concentration analyzer 43, the interaction coefficients g and i in the quadratic polynomial model of the total phosphorus removal rate in step S2 are corrected. When the influent suspended solid concentration > 50 mg / L, the coefficient g is increased by 10 - 20%, and the coefficient i is decreased by 5 - 10%; when the influent suspended solid concentration ≤ 50 mg / L, the coefficients g and i maintain the reference values.

[0101] AsFigure 1 As shown, a pH sensor 6 and a temperature sensor 7 are also provided in the high-efficiency sedimentation tank 4.

[0102] During application, in step S2, the controller 5 accesses the pH sensor 6 and the temperature sensor 7 provided in the high-efficiency sedimentation tank 4 to obtain the pH value and water temperature data in the high-efficiency sedimentation tank 4 in real time.

[0103] Correction of the interaction influence coefficients e and h: When the controller 5 detects that the pH value exceeds the range of 6.5 - 8.0 according to the pH value data in the high-efficiency sedimentation tank 4, it dynamically corrects the interaction coefficients e and h according to the pH deviation value. If the pH deviation value > 0.5, the coefficient e increases by 10 - 15%, and the coefficient h decreases by 5 - 10%; if the pH deviation value < -0.5, the coefficient e decreases by 10 - 15%, and the coefficient h increases by 5 - 10%.

[0104] At the same time, when the water temperature in the high-efficiency sedimentation tank 4 obtained by the controller 5 is lower than 10°C, the coefficients b and d are respectively increased by 20% - 30% to compensate for the decrease in the flocculation reaction rate caused by the low temperature.

[0105] Based on the second embodiment of the precise phosphorus removal control method for the high-efficiency sedimentation tank with magnetic medium addition, the difference between this embodiment and the first embodiment is that in step S2, the limit value of the total phosphorus concentration in the effluent is 0.3 - 0.5 mg / L, and the controller 5 automatically selects a preset chemical dosing priority strategy according to the difference between the total phosphorus concentration in the effluent and the limit value of the total phosphorus concentration in the effluent: when the total phosphorus concentration in the influent > 3 mg / L, the dosing proportion of flocculant B is preferentially increased; when 1 mg / L ≤ the total phosphorus concentration in the influent ≤ 3 mg / L, the synergistic dosing amount of magnetic powder A and coagulant aid C is preferentially optimized.

[0106] Specifically, for the feedback regulation at the influent end:

[0107] When the total phosphorus concentration in the influent > 3 mg / L, the dosing adjustment of flocculant B is as follows:

[0108] Whenever the total phosphorus concentration in the influent is detected to increase by 0.5 mg / L, the dosing proportion of flocculant B is increased by 5 - 8%, and at the same time, the dosing proportion of magnetic powder A is decreased by 3 - 5%, and the dosing proportion of coagulant aid C is decreased by 2 - 3%;

[0109] If the increase amplitude of the total phosphorus concentration in the influent continuously > 5 mg / L exceeds 30 minutes, the upper limit of the dosing proportion of flocculant B is increased to 80%, and the lower limits of the proportions of magnetic powder A and coagulant aid C are respectively decreased to 15% and 5%.

[0110] When 1 mg / L ≤ the total phosphorus concentration in the influent ≤ 3 mg / L, the dosing adjustment of magnetic powder A and coagulant aid C is as follows:

[0111] If the influent suspended solid concentration > 50 mg / L, the proportion of magnetic powder A is increased by 10 - 15%, and the proportion of coagulant aid C is decreased by 10 - 15%.

[0112] If the influent suspended solid concentration ≤ 50 mg / L, the proportion of magnetic powder A and coagulant aid C is evenly distributed at 1:1.

[0113] For the feedback regulation at the effluent end: When the difference between the value of the total phosphorus concentration in the effluent and the specified value of the total phosphorus concentration in the effluent ≤ 0.1 mg / L, the dosing ratio of magnetic powder A and coagulant aid C is temporarily adjusted to 2:1 until the total phosphorus concentration in the effluent is stably lower than the specified value of the total phosphorus concentration in the effluent.

[0114] Through the precise phosphorus removal control method based on the high - efficiency sedimentation tank with magnetic medium, in terms of the dosing control accuracy of chemicals, the coordinated optimization of multiple water quality parameters for dosing control, the reduction of operating costs, and the improvement of the automation level of the sewage treatment process, it has the following advantages:

[0115] Improve the dosing control accuracy of chemicals. By setting an influent flowmeter 11, an influent total phosphorus concentration analyzer 12, and an influent on - line suspended solid concentration analyzer 13 at the sewage inlet end of the magnetic powder dosing tank 1 on the sewage inlet side, the influent flow rate, influent total phosphorus concentration, and influent suspended solid concentration are collected in real - time. Combining with the quadratic polynomial model of the total phosphorus removal rate based on multivariable dynamic modeling, the theoretical dosing amounts A0, B0, and C0 of magnetic powder, flocculant, and coagulant aid are accurately calculated, which can effectively avoid the problems of dosing lag and inaccuracy caused by estimating the dosing amount by the traditional empirical method, and improve the accuracy and real - time performance of dosing control of chemicals.

[0116] Achieve coordinated optimization control of multiple parameters. Construct a quadratic polynomial model of the total phosphorus removal rate based on the interaction of magnetic powder, flocculant, and coagulant aid, and comprehensively consider the non - linear coupling relationship between different chemicals and hydraulic conditions, so that the dosing amount of chemicals can dynamically respond to the fluctuation of influent water quality, realize multivariable coordinated regulation and optimization, improve the stability and reliability of the phosphorus removal efficiency, and avoid over - dosing to control the phosphorus removal cost.

[0117] Reduce the operating costs: Through accurate calculation and dynamic adjustment mechanism, effectively avoid the phenomenon of over - dosing of chemicals commonly existing in the traditional automatic chemical dosing system, reduce the usage amount of chemicals and magnetic powder, reduce the sludge production and treatment cost, and improve the economy of the entire phosphorus removal process.

[0118] Improve the automation level of the magnetic medium enhanced sedimentation tank system. Through the influent flowmeter 11, influent total phosphorus concentration analyzer 12, influent online suspended solids concentration analyzer 13, effluent flowmeter 41, effluent total phosphorus concentration analyzer 42 and effluent online suspended solids concentration analyzer 43, multi-point online monitoring is carried out for the sewage phosphorus removal process, and a closed-loop feedback control system is formed with the controller 5. Combining the preset effluent limit value of the effluent total phosphorus concentration and the threshold value of the effluent total phosphorus fluctuation value, the chemical dosing amount is dynamically corrected, which can significantly improve the automation and intelligence level of the system, reduce the frequency of manual intervention, simplify the operation process, and enhance the convenience and efficiency of operation management.

[0119] In summary, the precise phosphorus removal control method provided in this technical solution has significantly improved in terms of phosphorus removal effect, operation cost control and process automation control compared with the existing sewage sedimentation phosphorus removal technology, and is applicable to the construction of an automation control system for the advanced phosphorus removal process in sewage treatment plants.

[0120] By implementing the precise phosphorus removal control method in the magnetic medium enhanced sedimentation tank, in practical applications, the influent of the magnetic powder dosing tank 1 is the effluent of the previous secondary sedimentation tank. After long-term stable operation, the total phosphorus concentration of the effluent of the secondary sedimentation tank is 1.158 mg / L.

[0121] The magnetic powder used is Fe3O4, the flocculant is aluminum sulfate, and the coagulant aid is PAM.

[0122] The set effluent total phosphorus limit value is 0.35 mg / L, and the effluent suspended solids concentration is 8 mg / L.

[0123] After implementing the experiment, the quadratic polynomial expression of the total phosphorus removal rate is determined as:

[0124] Total phosphorus removal rate = 8.875 + 2.01498×B - 181.83×C + 16.6745×A - 0.215×B×C + 0.00025×B×A + 9.95×C×A - 0.01433×B 2 +282.8×C 2 -2.572×A 2 ;

[0125] The controller 5 calculates the theoretical dosing amounts as A0 = 3.75 mg / L, B0 = 0.054 mg / L, and C0 = 0.39 mg / L respectively through the quadratic polynomial expression according to the data of the influent flowmeter 11 and the influent total phosphorus concentration analyzer 12.

[0126] After processes such as magnetic powder addition, mixing, flocculation, and sedimentation, the total phosphorus concentration in the effluent and the suspended solid concentration in the effluent collected by the total phosphorus concentration analyzer 42 and the on-line suspended solid concentration analyzer 43 of the effluent are 0.195 mg / L and 4 mg / L respectively, meeting the requirements of the effluent limit value and the effluent discharge limit value.

[0127] Among them, the theoretical total phosphorus removal rate predicted by the quadratic polynomial model of the total phosphorus removal rate is 81.65%, the actually measured total phosphorus removal rate is 81.11%, and the deviation rate is 0.6%.

[0128] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described.

Claims

1. A precise phosphorus removal control method based on an intensified magnetic medium high - efficiency sedimentation tank, characterized in that: It includes a magnetic powder dosing tank, a mixing tank, a flocculation tank, and a high - efficiency sedimentation tank arranged in sequence along the direction from sewage inlet to outlet, and a controller is set in the sedimentation phosphorus removal process room; during the precise phosphorus removal process, the controller collects data, calculates the dosing amount of chemicals according to the precise phosphorus removal steps, and controls the dosing of magnetic powder, flocculant, and coagulant aid to the magnetic powder dosing tank, mixing tank, and flocculation tank in a way of dynamically limiting the dosing amount, so as to precisely control the dosing amount of magnetic powder, flocculant, and coagulant aid to achieve precise phosphorus removal; Among them, the precise phosphorus removal steps are: S1. Real - time collection of influent parameters: An influent flowmeter, an influent total phosphorus concentration analyzer, and an influent online suspended solid concentration analyzer are set at the sewage inlet end of the magnetic powder dosing tank to respectively collect the influent flow rate, influent total phosphorus concentration, and influent suspended solid concentration at the inlet end in real time; S2. Multivariable dynamic modeling and collaborative calculation of chemical dosing amount: Based on the interaction relationship of the magnetic powder dosing amount A, flocculant dosing amount B, and coagulant aid dosing amount C, a quadratic polynomial model of total phosphorus removal rate is established; According to the influent flow rate, influent total phosphorus concentration, and the preset effluent total phosphorus concentration limit value, the controller solves the quadratic polynomial model of total phosphorus removal rate to dynamically calculate the theoretical dosing amounts A0, B0, and C0 of magnetic powder, flocculant, and coagulant aid; S3. Chemical dosing: The magnetic powder is dosed into the magnetic powder dosing tank according to A0, the flocculant is dosed into the mixing tank according to B0, and the coagulant aid is dosed into the flocculation tank according to C0. The chemicals are mixed with the flowing sewage in each tank in sequence, and flocculation is completed in the flocculation tank, and finally sedimentation is completed in the high - efficiency sedimentation tank; S4. Feedback regulation of effluent parameters: An effluent flowmeter, an effluent total phosphorus concentration analyzer, and an effluent online suspended solid concentration analyzer are set at the effluent end of the high - efficiency sedimentation tank to monitor the effluent total phosphorus concentration and effluent suspended solid concentration at the effluent end in real time; The controller judges whether the effluent is qualified by comparing the measured effluent total phosphorus concentration with the effluent total phosphorus concentration limit value: If the effluent total phosphorus concentration > the effluent total phosphorus concentration limit value, it is judged that the effluent is unqualified, then the effluent total phosphorus fluctuation value is obtained according to the deviation value between the effluent total phosphorus concentration and the effluent total phosphorus concentration limit value, and the dosing amounts of A, B, and C are dynamically corrected with a preset adjustment range; If the effluent total phosphorus concentration ≤ the effluent total phosphorus concentration limit value, it is judged that the effluent is qualified, and the fluctuation range of the effluent total phosphorus fluctuation value is lower than the preset effluent total phosphorus fluctuation value threshold, then the current chemical dosing amount is maintained; The quadratic polynomial model for the total phosphorus removal rate is: Total phosphorus removal rate = a + b×B - c×C + d×A - e×B×C + f×B×A + g×C×A - h×B 2 + i×C 2 - j×A 2 ; where a is the safety coefficient, and b to j are the interaction influence coefficients of magnetic powder, flocculant, and coagulant aid; The value of the safety factor a is 8.80 - 8.95, which is used to compensate for the prediction error of the total phosphorus removal rate caused by the deviation of influent data collection; The coefficients b to j of the quadratic polynomial model of total phosphorus removal rate are determined by orthogonal experiment and multiple regression analysis, including: within the range of influent total phosphorus concentration of 1 - 4mg / L, multiple groups of experiments are carried out by changing the dosing amount combinations of A, B, and C, the total phosphorus removal rate data are recorded, and the values of each coefficient b to j are obtained by least - squares fitting.

2. The precise phosphorus removal control method based on a magnetized medium high-efficiency sedimentation tank according to claim 1, wherein In step S4, the adjustment range has a piece - wise linear relationship with the effluent total phosphorus fluctuation value: when the effluent total phosphorus fluctuation value ≤ 0.1mg / L, the adjustment range is 2 - 5% of the theoretical dosing amount; When 0.1 mg / L < the fluctuation value of the total phosphorus in the effluent ≤ 0.3 mg / L, the adjustment range is 5 - 10% of the theoretical dosage; When the fluctuation value of the total phosphorus in the effluent > 0.3 mg / L, the adjustment range is 10 - 15% of the theoretical dosage.

3. The precise phosphorus removal control method based on a magnetized medium high-efficiency sedimentation tank according to claim 1, characterized in that, In step S3, the stirring intensities of the magnetic powder dosing tank, the mixing tank, and the flocculation tank are linked and controlled respectively with the dosages of A, B, and C: the stirring speed of the magnetic powder dosing tank is positively correlated with A, the stirring speed of the mixing tank is positively correlated with B, and the stirring speed of the flocculation tank is negatively correlated with C.

4. The precise phosphorus removal control method based on a magnetic medium high-efficiency sedimentation tank according to claim 1, characterized in that, In step S2, the limit value of the total phosphorus concentration in the effluent is 0.3 - 0.5 mg / L, and the controller automatically selects a preset chemical dosing priority strategy according to the total phosphorus concentration in the influent: When the total phosphorus concentration in the influent > 3 mg / L, the dosing proportion of the flocculant B is preferentially increased; When 1 mg / L ≤ the total phosphorus concentration in the influent ≤ 3 mg / L, the co-dosage of the magnetic powder A and the coagulant aid C is preferentially optimized.

5. The precise phosphorus removal control method based on a magnetization medium high-efficiency sedimentation tank according to claim 2, wherein The data of the influent suspended solid concentration analyzer, the influent suspended solid concentration, is used to correct the interaction coefficients g and i in the quadratic polynomial model of the total phosphorus removal rate in step S2: When the influent suspended solid concentration > 50 mg / L, the coefficient g is increased by 10 - 20%, and the coefficient i is decreased by 5 - 10%; When the influent suspended solid concentration ≤ 50 mg / L, the coefficients g and i maintain the reference values.

6. The precise phosphorus removal control method based on an intensified magnetic medium high-efficiency sedimentation tank according to claim 1, wherein It also includes step S5, optimization of the magnetic powder recovery efficiency: the controller dynamically adjusts the dosage of A according to the magnetic powder content value of the bottom sludge in the high-efficiency sedimentation tank, so that the mass ratio of the recovered magnetic powder to the newly added magnetic powder is controlled within 1:0.3 - 1:0.

8.

7. The precise phosphorus removal control method based on a magnetic medium high-efficiency sedimentation tank according to claim 2, characterized in that A pH sensor and a temperature sensor are also provided in the high-efficiency sedimentation tank; In the said step S2, the controller obtains the pH value and the water temperature data in the high-efficiency sedimentation tank in real time according to the pH sensor and the temperature sensor; When it is detected that the pH value exceeds the range of 6.5 - 8.0, the coefficients e and h in the quadratic polynomial model of the total phosphorus removal rate are dynamically corrected according to the pH deviation value: If the pH deviation value > 0.5, the coefficient e is increased by 10 - 15%, and the coefficient h is decreased by 5 - 10%; If the pH deviation value < -0.5, the coefficient e is decreased by 10 - 15%, and the coefficient h is increased by 5 - 10%; Meanwhile, when the water temperature is lower than 10 °C, the coefficients b and d are respectively increased by 20 - 30% to compensate for the decrease in the flocculation reaction rate caused by the low temperature.

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