A control method and device for PAM dosing of an efficient sedimentation tank

Abstract

This invention relates to a control method and apparatus for PAM dosing in a high-efficiency sedimentation tank, comprising: acquiring the current PAM mass concentration and current influent process parameters; calculating the current basic PAM dosage based on the current PAM mass concentration, current influent flow rate, current influent suspended solids concentration, and current influent orthophosphate concentration; wherein the basic dosage is positively correlated with the current influent suspended solids concentration and the chemical precipitation solids load caused by changes in the current influent orthophosphate concentration; calculating the current PAM feedback correction amount based on a preset optimization objective function and constraints, according to the current effluent suspended solids concentration and current effluent total phosphorus concentration; determining the final PAM dosage based on the basic dosage and feedback correction amount, and controlling the PAM dosing accordingly, thereby solving the problems of floc settling deterioration and sludge loss caused by phosphorus load fluctuations during chemical phosphorus removal through the above-mentioned dual closed-loop control strategy.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a control method and apparatus for adding PAM to a high-efficiency sedimentation tank. Background Technology

[0002] In the chemical phosphorus removal process of urban wastewater treatment plants, high-efficiency sedimentation tanks (such as magnetic coagulation and high-density sedimentation tanks) typically employ a compound addition mode of "inorganic flocculants (such as polyaluminum chloride PAC and polyferric sulfate PFS) + organic polymeric coagulant aid (PAM)". Among them, PAM mainly acts as an adsorption bridging agent, promoting the aggregation of micro-flocs into large and dense flocs to accelerate sedimentation and prevent sludge loss.

[0003] Currently, existing technologies for controlling PAM dosing mainly fall into two categories: one is setting the PAM dosage to a fixed value or adding it only according to the influent flow rate; the other, in a few intelligent control devices, uses equipment such as floc imaging devices to sense the floc morphology and adjust the PAM accordingly. However, these methods have the following problems: existing control strategies generally focus on optimizing the dosage of main reagents (such as PAC and PFS), considering PAM to play only an auxiliary role, and neglecting the intelligent control of PAM. However, for wastewater treatment plants with severe sludge loss in the secondary sedimentation tank and large fluctuations in effluent suspended solids, the PAM dosage directly determines the settling performance of the flocs. Insufficient PAM dosage will lead to fine flocs and slow settling, causing sludge loss and resulting in excessive suspended solids and total phosphorus in the effluent; excessive PAM dosage will increase sludge viscosity, leading to dewatering difficulties and waste of reagents.

[0004] Therefore, how to achieve precise dynamic control of PAM dosing is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a control method and device for PAM addition in high-efficiency sedimentation tanks, which solves the technical problems of insufficient attention to PAM addition control and lack of precise dynamic adjustment in the prior art.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0009] In a first aspect, embodiments of the present invention provide a control method for PAM dosing in a high-efficiency sedimentation tank, comprising:

[0010] Obtain the current PAM mass concentration and current influent process parameters; wherein, the current influent process parameters include the current influent flow rate, the current influent suspended solids concentration, and the current influent orthophosphate concentration;

[0011] The basic dosage of PAM is calculated based on the current PAM mass concentration, current influent flow rate, current influent suspended solids concentration, and current influent orthophosphate concentration. The basic dosage is positively correlated with the current influent suspended solids concentration and the chemical precipitation solids load caused by changes in the current influent orthophosphate concentration.

[0012] Based on the preset optimization objective function and constraints, the feedback correction amount of the current PAM is calculated according to the current effluent suspended solids concentration and the current effluent total phosphorus concentration.

[0013] The final dosage of PAM is determined based on the base dosage and feedback correction, and the dosage of PAM is controlled accordingly.

[0014] Optionally, the formula for calculating the basic dosage is:

[0015] ;

[0016] In the formula, This represents the basic dosage; k1 and k2 are the PAM dosage coefficients corresponding to the influent suspended solids load; k3 represents the current influent suspended solids concentration; k3 is the PAM dosage coefficient corresponding to the phosphorus load. This represents the current orthophosphate concentration in the influent. This represents the current inflow rate; This represents the current PAM mass concentration.

[0017] Optionally, based on a preset optimization objective function and constraints, the feedback correction amount for the current PAM is calculated according to the current effluent suspended solids concentration and the current effluent total phosphorus concentration, including:

[0018] Establish a prediction model; wherein, the prediction model is used to predict the effluent suspended solids concentration and effluent total phosphorus concentration at future times based on the change sequence of PAM dosage correction.

[0019] Based on the prediction model, the optimization objective function is defined as minimizing the sum of squared errors between the predicted effluent suspended solids concentration and the predicted effluent total phosphorus concentration at future times and their respective set target values ​​within the prediction time domain, and minimizing the fluctuation of PAM dosage.

[0020] Constraints are set, including upper and lower limits for PAM dosage. In each control cycle, the current effluent suspended solids concentration and current effluent total phosphorus concentration are used as the initial state. Based on the prediction model, the PAM dosage correction sequence that satisfies the constraints and optimizes the objective function is resolved. According to the rolling optimization principle of MPC, the first value in the PAM dosage correction sequence is taken as the feedback correction for the current control cycle.

[0021] Optionally, the control method further includes: when the increase in the current influent suspended solids concentration or the current influent orthophosphate concentration exceeds a preset threshold within a preset time, increasing the PAM addition coefficients k1 and k2 corresponding to the influent suspended solids load and the PAM addition coefficient k3 corresponding to the phosphorus load in the calculation expression of the basic addition amount.

[0022] Optionally, the control method further includes: when the current influent suspended solids concentration is detected to be lower than the preset lower limit and the current effluent suspended solids concentration and the current effluent total phosphorus concentration both meet the standards, multiplying the basic dosage by an energy-saving coefficient less than 1 to reduce PAM agent consumption.

[0023] Secondly, embodiments of the present invention provide a control device for PAM dosing in a high-efficiency sedimentation tank, comprising:

[0024] The acquisition module is used to acquire the current PAM mass concentration and the current influent process parameters; wherein, the current influent process parameters include the current influent flow rate, the current influent suspended solids concentration, and the current influent orthophosphate concentration;

[0025] The first calculation module is used to calculate the basic dosage of PAM based on the current PAM mass concentration, current influent flow rate, current influent suspended solids concentration, and current influent orthophosphate concentration; wherein, the basic dosage is positively correlated with the current influent suspended solids concentration and the chemical precipitation solids load caused by the change in the current influent orthophosphate concentration.

[0026] The second calculation module is used to calculate the feedback correction amount of the current PAM based on the current suspended solids concentration and the current total phosphorus concentration in the effluent, according to the preset optimization objective function and constraints.

[0027] The control module is used to determine the final dosage of PAM based on the basic dosage and feedback correction, and to control the dosage of PAM accordingly.

[0028] Optionally, the formula for calculating the basic dosage is:

[0029] ;

[0030] In the formula, This represents the basic dosage; k1 and k2 are the PAM dosage coefficients corresponding to the influent suspended solids load; k3 represents the current influent suspended solids concentration; k3 is the PAM dosage coefficient corresponding to the phosphorus load. This represents the current orthophosphate concentration in the influent. This represents the current inflow rate; This represents the current PAM mass concentration.

[0031] Optionally, the second calculation module is specifically used for: establishing a prediction model; wherein the prediction model is used to predict the effluent suspended solids concentration and the effluent total phosphorus concentration at future times based on the change sequence of PAM dosage correction; based on the prediction model, defining the optimization objective function as minimizing the sum of squared errors between the predicted effluent suspended solids concentration and the predicted effluent total phosphorus concentration at future times and their respective set target values ​​within the prediction time domain, and minimizing the fluctuation of the PAM dosage; setting constraints, including upper and lower limits of the PAM dosage, and in each control cycle, using the current effluent suspended solids concentration and the current effluent total phosphorus concentration as the initial state, resolving the PAM dosage correction sequence that satisfies the constraints and optimizes the objective function based on the prediction model, and taking the first value in the PAM dosage correction sequence as the feedback correction for the current control cycle according to the rolling optimization principle of MPC.

[0032] Optionally, the control device further includes: an amplification module, used to increase the PAM addition coefficients k1 and k2 corresponding to the influent suspended solids load and the PAM addition coefficient k3 corresponding to the phosphorus load in the calculation expression of the basic addition amount when the increase in the current influent suspended solids concentration or the current influent orthophosphate concentration within a preset time exceeds a preset threshold.

[0033] Optionally, the control device further includes a reduction module, which is used to multiply the basic dosage by an energy-saving coefficient less than 1 when the current influent suspended solids concentration is detected to be lower than a preset lower limit and the current effluent suspended solids concentration and the current effluent total phosphorus concentration both meet the standards, so as to reduce the consumption of PAM reagent.

[0034] Thirdly, embodiments of this application provide a storage medium storing a computer program, which, when executed by a processor, performs the method described in the first aspect or any optional implementation thereof.

[0035] Fourthly, embodiments of this application provide an electronic device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, they perform the method described in the first aspect or any optional implementation of the first aspect.

[0036] Fifthly, this application provides a computer program product that, when run on a computer, causes the computer to perform the method in the first aspect or any possible implementation thereof.

[0037] (III) Beneficial Effects

[0038] The beneficial effects of this invention are:

[0039] This application provides a control method and apparatus for PAM dosing in a high-efficiency sedimentation tank. The method involves acquiring the current PAM mass concentration and current influent process parameters. These parameters include the current influent flow rate, current influent suspended solids concentration, and current influent orthophosphate concentration. The basic PAM dosage is calculated based on these parameters. The basic dosage is related to the current influent suspended solids concentration and the negative chemical precipitation solids caused by changes in the current influent orthophosphate concentration. The loads are positively correlated. Based on the preset optimization objective function and constraints, the feedback correction amount of the current PAM is calculated according to the current effluent suspended solids concentration and the current effluent total phosphorus concentration. The final dosage of the current PAM is determined according to the basic dosage and the feedback correction amount, and the PAM dosage is controlled accordingly. By establishing a feedforward model based on the influent load (suspended solids, orthophosphate and flow rate) and a feedback correction mechanism based on the effluent indicators, the precise dynamic control of PAM dosage is achieved. Under the premise of ensuring that the effluent suspended solids and orthophosphate meet the standards, the consumption of reagents is minimized and sludge runoff is prevented. Attached Figure Description

[0040] Figure 1 A framework diagram of an online control system provided in an embodiment of this application is shown;

[0041] Figure 2 A flowchart of a control method for PAM dosing in a high-efficiency sedimentation tank, provided in an embodiment of this application, is shown.

[0042] Figure 3 A structural block diagram of a control device for adding PAM to a high-efficiency sedimentation tank, provided in an embodiment of this application, is shown. Detailed Implementation

[0043] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Despite some progress in chemical phosphorus removal control, existing technologies still have the following significant shortcomings in the intelligent dosing control of PAM (coagulant aid):

[0045] Failure to accurately balance the complex relationship between PAM, influent suspended solids, and dosage:

[0046] The addition of PAM is not only related to the suspended solids (SS) in the influent, but also a complex process where "too much of a good thing can be bad." Existing algorithms often calculate based solely on a fixed charge ratio or simple concentration correlation, lacking consideration of the "marginal effect" of PAM dosage.

[0047] Specifically, if the amount of PAM added is too small relative to the influent suspended solids and generated chemical precipitates, the polymer chains cannot be fully adsorbed and bridged, resulting in fine flocs with poor settling performance. This easily leads to sludge runoff in the secondary settling tank, causing a simultaneous increase in effluent suspended solids and total phosphorus (TP). Conversely, if too much PAM is added, although the effluent becomes clearer, it will bring new problems: the formed flocs will be too dense, making sludge dewatering difficult, or the "protective colloid" effect of the polymer chains will cause the flocs to become unstable, increasing the cost of chemicals and the pressure of sludge disposal.

[0048] Lack of mechanistic coupling with the chemical phosphorus removal process:

[0049] Existing intelligent control systems (such as the intelligent magnetic coagulation wastewater treatment system and method disclosed in publication number CN121063659A) comprehensively control multiple agents, but their control logic is relatively complex, relying on expensive imaging equipment (ferruginous floc imagers), and mainly focusing on the special process of magnetic coagulation. In conventional high-efficiency sedimentation tanks or secondary sedimentation tanks, there is a lack of models that establish a direct algorithmic relationship between influent suspended solids concentration, orthophosphate concentration, and PAM dosage. In fact, the higher the influent phosphorus load, the more metal phosphate precipitates (AlPO4 or HFO) are generated, and the more floc nuclei need to be bridged, so the demand for PAM should increase. However, existing algorithms often ignore this chemical mechanism relationship.

[0050] The feedback mechanism is lagging and limited.

[0051] For PAM control, existing feedback largely relies on manual observation of the sludge interface or offline sludge volume index (SVI) testing, lacking real-time closed-loop feedback based on effluent suspended solids and total phosphorus. When the influent suspended solids load changes abruptly, fixed dosing or dosing based solely on influent flow rate ratios cannot respond promptly, resulting in poor system shock resistance.

[0052] In summary, existing technologies lack consideration of the impact mechanism of phosphorus load changes on PAM demand in chemical phosphorus removal processes, and also lack dynamic balance adjustment of the complex relationship between PAM dosage and suspended solids settling / dewatering performance. Therefore, they have technical problems of insufficient control precision and poor adaptability in dealing with phosphorus load fluctuations and preventing sludge runoff.

[0053] Based on this, embodiments of this application provide a control method and apparatus for PAM dosing in a high-efficiency sedimentation tank. This method involves acquiring the current PAM mass concentration and current influent process parameters. The current influent process parameters include the current influent flow rate, current influent suspended solids concentration, and current influent orthophosphate concentration. The basic PAM dosage is calculated based on these parameters. The basic dosage is related to the current influent suspended solids concentration and the chemical precipitation solids caused by changes in the current influent orthophosphate concentration. The loads are all positively correlated. Based on the preset optimization objective function and constraints, the feedback correction amount of the current PAM is calculated according to the current effluent suspended solids concentration and the current effluent total phosphorus concentration. The final dosage of the current PAM is determined according to the basic dosage and the feedback correction amount, and the PAM dosage is controlled accordingly. By establishing a feedforward model based on the influent load (suspended solids, orthophosphate and flow rate) and a feedback correction mechanism based on the effluent indicators, the precise dynamic control of PAM dosage is achieved. Under the premise of ensuring that the effluent suspended solids and orthophosphate meet the standards, the consumption of reagents is minimized and sludge runoff is prevented.

[0054] In other words, this invention proposes a dual closed-loop control strategy: First, based on the dual-matrix bridging mechanism of "suspended solids-metal phosphate precipitation", the influent orthophosphate concentration is introduced as an independent feedforward variable into the calculation of the basic PAM dosage, quantifying the incremental demand of precipitates for flocculants; Second, a multi-objective optimization function is constructed with the effluent suspended solids concentration (SS) and total phosphorus concentration (TP) meeting the standards as tracking targets and the upper and lower limits of PAM dosage as hard constraints, and the feedback correction is solved in real time. Thus, this application achieves precise dynamic control of PAM that balances efficient phosphorus removal, prevention of sludge runoff, and minimization of chemical consumption.

[0055] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0056] Please see Figure 1 , Figure 1 A framework diagram of an online control system provided in an embodiment of this application is shown. Figure 1 As shown, the online control system includes:

[0057] The online monitoring module includes: an online flow meter (Q_in), an online suspended solids concentration meter (SS_in), and an online orthophosphate analyzer (PO4_in) installed at the inlet; an online PAM flow meter (Qd) and a PAM mass concentration detector (C_PAM) installed at the dosing end; and an online total phosphorus analyzer (TP_out) and an online suspended solids concentration meter (SS_out) installed at the outlet.

[0058] Data Acquisition and Processing Module: This module cleans and processes the data collected by the online monitoring module, providing reliable input to the decision control module. Data cleaning includes: removing outliers that are significantly outside the reasonable range due to instrument malfunctions or communication anomalies (e.g., negative values ​​or exceeding the upper limit of the influent suspended solids concentration); smoothing high-frequency noise signals using moving average or median filtering methods; and performing linear interpolation to complete transient data gaps. Data calculation includes: unifying the dimensions and converting the units of the data collected by each instrument.

[0059] Decision control module: Based on the control method for PAM dosing in high-efficiency sedimentation tanks of this application, the module processes the data after it has been processed by the data collection and processing module to output the PAM dosing flow rate. The specific process of this control method can be found in the relevant description below.

[0060] Dynamic execution module: Converts the PAM dosing flow rate into a pump frequency control signal, and adjusts the PAM dosing amount according to the control signal.

[0061] Human-machine interface: Displays online instrument monitoring data, decision control module decision data, and control signal data, and supports data viewing, retrieval, and input.

[0062] See also Figure 2 , Figure 2 A flowchart illustrating a control method for PAM dosing in a high-efficiency sedimentation tank, provided in an embodiment of this application, is shown. It should be understood that this control method can be executed by a control device for PAM dosing in a high-efficiency sedimentation tank, and the specific device can be configured according to actual needs; this embodiment is not limited thereto. For example, the control device can be a computer or a server, etc. Specifically, the control method includes:

[0063] Step S210: Obtain the current PAM mass concentration and current influent process parameters. The current influent process parameters include the current influent flow rate, current influent suspended solids concentration, and current influent orthophosphate concentration related to phosphorus load.

[0064] Specifically, the current PAM mass concentration C_PAM can be obtained using a PAM mass concentration detector installed at the dosing end; the current influent flow rate Q_in, current influent suspended solids concentration SS_in, and current influent orthophosphate concentration PO4_in can be obtained using an online flow meter, an online suspended solids concentration meter, and an online orthophosphate analyzer installed at the influent end.

[0065] Step S220: Calculate the current basic PAM dosage based on the current PAM mass concentration, current influent flow rate, current influent suspended solids concentration, and current influent orthophosphate concentration. The basic dosage is positively correlated with both the current influent suspended solids concentration and the chemical precipitation solids load caused by changes in the current influent orthophosphate concentration.

[0066] It should be understood that the calculation formula for the basic dosage of PAM can be set according to actual needs, and the embodiments of this application are not limited thereto.

[0067] Optionally, based on the chemical phosphorus removal mechanism, the metal phosphate precipitates and hydrated oxides generated after PAC addition require PAM for bridging and flocculation. Therefore, the basic dosage of PAM... It is positively correlated with both influent suspended solids (bridging matrix) and influent phosphorus (chemical precipitate).

[0068] Furthermore, based on the current PAM mass concentration, current influent flow rate, current influent suspended solids concentration, and influent orthophosphate concentration related to phosphorus load, the current solids / flocculation load of the system is estimated, and the current basic PAM dosage is calculated accordingly. The formula for calculating the current basic PAM dosage is as follows:

[0069] ;

[0070] In the formula, The basic dosage is indicated; k1 and k2 are the PAM dosage coefficients corresponding to the influent suspended solids load, where k1 is the proportional coefficient and k2 is the exponential coefficient. k3 represents the current influent suspended solids concentration; k3 is the PAM dosage coefficient corresponding to the phosphorus load. This represents the current orthophosphate concentration in the influent. This represents the current inflow rate; This represents the current PAM mass concentration.

[0071] According to this formula, the higher the suspended solids in the influent, the more bridging agent is needed; the higher the phosphorus in the influent (and the corresponding added PAC), the more inorganic precipitate nuclei are generated, requiring more PAM to encapsulate and aggregate them into large flocs.

[0072] It's important to note that in chemical phosphorus removal processes, the basic dosage of PAM (Polyphosphate Acetate) is not solely related to the suspended solids (SS) in the influent, but also depends on the amount of chemical precipitates generated by the orthophosphate concentration. Specifically, the influent suspended solids are the direct target of PAM bridging and flocculation; the more suspended solids, the more PAM is needed to agglomerate these particles into large flocs. Therefore, the dosage is positively correlated with the SS concentration. On the other hand, when the orthophosphate concentration in the wastewater is high, more inorganic flocculants such as PAC (polyaluminum chloride) are needed to react with it, generating a large amount of phosphate precipitates (such as aluminum phosphate) and hydrated metal oxide particles. These tiny chemical precipitates also require the adsorption and bridging effect of PAM to be effectively captured, aggregated into large flocs, and settled. In other words, the higher the orthophosphate concentration, the greater the resulting chemical precipitate solids load, and the greater the amount of PAM required. Therefore, the basic dosage of PAM is positively correlated with both the influent suspended solids concentration and the chemical precipitate solids load determined by the orthophosphate concentration.

[0073] Step S230: Based on the preset optimization objective function and constraints, calculate the feedback correction amount of the current PAM according to the current effluent suspended solids concentration and the current effluent total phosphorus concentration.

[0074] Specifically, the system acquires the current effluent suspended solids concentration SS_out and the current effluent total phosphorus concentration TP_out at fixed control cycles (e.g., 5-30 minutes). Since PAM dosing has significant nonlinear characteristics and constraints—insufficient dosing leads to poor floc settling (sludge runoff), while excessive dosing leads to sludge floating or dewatering difficulties (waste)—this application employs a rolling time-domain optimization-based model predictive control (MPC) algorithm to achieve optimal chemical consumption control while ensuring effluent compliance. In each control cycle, the system calculates the feedback correction ΔD based on the deviation between the current effluent indicators and the set target values ​​(SSset, TPset).

[0075] Specifically, the steps of the MPC algorithm include: establishing a prediction model; wherein the prediction model is used to predict the effluent suspended solids concentration and effluent total phosphorus concentration at future times based on the change sequence of PAM dosage correction; based on the prediction model, defining the optimization objective function as minimizing the sum of squared errors between the predicted effluent suspended solids concentration and the predicted effluent total phosphorus concentration at future times and their respective set target values ​​within the prediction time domain, and minimizing the fluctuation of the PAM dosage; setting constraints, including upper and lower limits for the PAM dosage, and in each control cycle, using the current effluent suspended solids concentration and current effluent total phosphorus concentration as the initial state, resolving the PAM dosage correction sequence that satisfies the constraints and optimizes the objective function based on the prediction model, and taking the first value in the PAM dosage correction sequence as the feedback correction ΔD for the current control cycle according to the rolling optimization principle of MPC. This process is executed automatically in each control cycle, without the need to separately determine whether the effluent indicators deviate from the set values.

[0076] First, in the decision control module, a simplified dynamic model capable of predicting future effluent water quality is established. The input to this model is the current sequence of PAM dosage correction increments, and the output is the effluent suspended solids and total phosphorus within the future prediction time domain N (e.g., the next 6 control cycles).

[0077] This model can be implemented using the following autoregressive moving average (ARX) or state-space equation:

[0078] ;

[0079] In the formula, This represents the effluent index vector at time k+1 (including effluent suspended solids concentration SS_out and effluent total phosphorus concentration TP_out); A, B, and C are model parameters, which can be identified through historical data or updated adaptively online. This represents the effluent index vector at time k (including effluent suspended solids concentration SS_out and effluent total phosphorus concentration TP_out).

[0080] Secondly, the optimal value is obtained by optimizing the objective function to minimize the effluent error and reagent consumption in the future prediction time domain. Minimizing these effluent error and reagent consumption means simultaneously pursuing two control objectives while ensuring effluent quality meets standards: first, minimizing the sum of squared errors between the predicted effluent suspended solids concentration and predicted effluent total phosphorus concentration and their respective set target values ​​in the future prediction time domain, thus ensuring stable effluent quality compliance; second, minimizing the fluctuation of PAM dosage, i.e., suppressing drastic changes in dosage to avoid reagent waste and system instability caused by large fluctuations in dosage. It should be noted that "minimizing reagent consumption" here does not mean minimizing the absolute value of PAM dosage, but rather reducing ineffective consumption and waste caused by excessive dosage by suppressing dosage fluctuations. The objective function is defined as follows:

[0081] ;

[0082] In the formula, J represents the objective function value; N represents the prediction time domain (the number of control cycles for future prediction). Indicates the weighting coefficient for suspended matter; SS represents the predicted suspended solids concentration in the effluent at time k+j; set This indicates the set target value for the concentration of suspended solids in the effluent; Weighting coefficients representing the total phosphorus concentration in the effluent; TP represents the predicted total phosphorus concentration in the effluent at time k+j. set This indicates the target value for the total phosphorus concentration in the effluent; This indicates the control weight, used to suppress drastic fluctuations in PAM dosage and prevent reagent waste; This represents the change in the PAM dosage correction at time k+j (or the correction value relative to the base dosage at time k+j).

[0083] In addition, for systems with high requirements for preventing mud leakage, increase For systems with stringent requirements for total phosphorus standards, increase... .

[0084] In addition, to address the issue that "adding too much PAM can also have an impact (waste, floating)," explicit constraints are added during the optimization process:

[0085] ;

[0086] In the formula, the lower limit constraint ( ): Ensure that the PAM dosage is not negative to maintain basic flocculation protection;

[0087] Upper limit constraint ( ): To prevent excessive PAM addition from causing sludge in the secondary sedimentation tank to float or form a "colloidal protective layer," which would make sludge dewatering difficult.

[0088] Furthermore, the above-mentioned constrained optimization problem can be solved using a nonlinear programming solver in a Python program.

[0089] Input: Current effluent suspended solids concentration, total phosphorus concentration deviation, and current basic dosage. ;

[0090] Output: The optimal correction sequence in the future prediction time domain [ΔD] t+1 ,ΔD t+2 ,...,ΔD t+N ];

[0091] Execution: Based on the rolling optimization principle of MPC, only the first value ΔD in the sequence is taken. t+1 This serves as the current feedback correction amount.

[0092] Step S240: Determine the final dosage of PAM based on the basic dosage and feedback correction, and control the dosage of PAM accordingly.

[0093] Specifically, the formula for calculating the final dosage is as follows:

[0094] ;

[0095] In the formula, This indicates the final dosage.

[0096] Then the system will The signal is converted into a control signal (such as 4-20mA or 0-10V) and sent to the PAM dosing pump frequency converter to adjust the dosing pump speed.

[0097] To cope with different water quality shocks, this method also includes the following adaptive logic:

[0098] When the increase in the current influent suspended solids concentration or the current influent orthophosphate concentration exceeds the preset threshold within a preset time, the PAM addition coefficients k1 and k2 corresponding to the influent suspended solids load and the PAM addition coefficient k3 corresponding to the phosphorus load in the calculation expression of the basic addition amount are increased.

[0099] It should be understood that the specific time and the specific value of the preset threshold can be set according to actual needs, and the embodiments of this application are not limited thereto. For example, when the current influent suspended solids concentration or the current influent orthophosphate concentration is detected to increase by more than the set threshold (e.g., 50%) within a short period of time (e.g., 5 minutes), the system automatically activates the "emergency flocculation mode" to instantly increase the k1 and k2 coefficients in the feedforward calculation in order to quickly form large flocs and prevent sludge loss.

[0100] It should also be understood that the specific adjustment process of k1 and the specific adjustment process of k2 can be set according to actual needs, and the embodiments of this application are not limited thereto.

[0101] For example, the adjustment formulas for k1 and k2 are as follows:

[0102] ;

[0103] ;

[0104] ;

[0105] ;

[0106] In the formula, and Let k1 and k2 be the adjusted values, respectively. and These are the base multiplication factor and base exponent factor used under normal operating conditions, respectively. Used to linearly scale the contribution of influent suspended solids concentration to PAM dosage. Used to control the degree of nonlinear influence of influent suspended solids concentration, when When the ratio is 1, it is a linear relationship; when it is greater than 1, it is an exponential growth relationship. This represents the sensitivity coefficient of k1 to the impact intensity of suspended solids in the influent, such as... It can be 0.3~0.8; This represents the sensitivity coefficient of k1 to the impact intensity of orthophosphate in the influent, such as... It can be 0.2~0.5; This represents the sensitivity coefficient of k2 to the impact intensity of suspended solids in the influent, such as... It can be 0.05~0.15; This represents the sensitivity coefficient of k2 to the impact intensity of influent orthophosphate, such as... It can be 0.02~0.08; The excess shock intensity factor (the portion exceeding the preset threshold) represents the concentration of suspended solids in the influent. The excess impact factor (the portion exceeding a preset threshold) represents the orthophosphate concentration; t represents time. This indicates a preset time window, such as 5 minutes. This indicates the threshold for the increase in SS, such as 0.5, which is equivalent to 50%. This indicates the PO4 increase threshold, such as 0.5.

[0107] In addition, when the current influent suspended solids concentration is detected to be lower than the preset lower limit and the current effluent suspended solids concentration and current effluent total phosphorus concentration both meet the standards, the basic dosage will be multiplied by an energy-saving coefficient less than 1.

[0108] It should be understood that the specific values ​​of the preset lower limit and the basic dosage can be set according to actual needs, and the embodiments of this application are not limited thereto.

[0109] For example, when the concentration of suspended solids in the influent is lower than the set lower limit (e.g., 10 mg / L) and the effluent meets the standards, the system automatically reduces the calculation weight of the basic dosage to maintain a minimum level of flocculation protection and prevent excessive flocculation from causing the sludge in the secondary sedimentation tank to float.

[0110] Therefore, by means of the above technical solution, this application has the following technical effects:

[0111] First, this application uses feedforward calculation and strong feedback control based on effluent suspended solids (SS) to adjust the PAM dosage in real time according to the influent SS load, ensuring that the formed flocs have excellent settling performance in the sedimentation tank, thereby effectively solving the problem of sludge runoff in the secondary sedimentation tank or high-efficiency sedimentation tank and ensuring that the effluent SS meets the standards stably.

[0112] Secondly, this application incorporates the influent orthophosphate concentration into the PAM feedforward model, enhancing the entrapment effect of PAM on phosphorus-containing precipitates and assisting PAC in improving the total phosphorus removal rate. Especially during influent load shocks, it can rapidly form large and dense flocs, effectively trapping tiny phosphorus-containing particles and preventing instantaneous exceedances of total phosphorus (TP) in the effluent, significantly enhancing the robustness of the chemical phosphorus removal process.

[0113] Furthermore, this application avoids the problems of overdosing (leading to difficulties in sludge dewatering and increased costs) or underdosing (leading to sludge runoff) caused by traditional fixed dosing or manual adjustment. Moreover, through feedforward and feedback synergistic optimization, PAM chemical consumption can be reduced by 20% to 50% while ensuring effluent quality meets standards, thereby reducing sludge disposal pressure and achieving a balance between economic and environmental benefits.

[0114] In addition, in the face of sudden increases in SS in influent during the rainy season or phosphorus load shocks caused by industrial wastewater, this application uses a feedforward model to quickly respond to changes in influent load and supplements it with an emergency flocculation mode to adaptively adjust the dosing coefficient. This can quickly stabilize the system operation, avoid water quality exceeding standards due to shock loads, and significantly improve the ability of wastewater treatment plants to cope with complex operating conditions.

[0115] It should be understood that the above-described control method for PAM dosing in high-efficiency sedimentation tanks is merely exemplary, and those skilled in the art can make various modifications based on the above method, and such modified solutions also fall within the protection scope of this application.

[0116] Please see Figure 3 , Figure 3This diagram illustrates a structural block diagram of a control device 300 for PAM dosing in a high-efficiency sedimentation tank, according to an embodiment of this application. It should be understood that the control device 300 is capable of executing the steps described in the above method embodiments. The specific functions of the control device 300 can be found in the description above; detailed descriptions are omitted here to avoid repetition. The control device 300 includes at least one software function module that can be stored in a memory or embedded in the operating system (OS) of the control device 300 in the form of software or firmware. Specifically, the control device 300 includes:

[0117] The acquisition module 310 is used to acquire the current PAM mass concentration and the current influent process parameters; wherein, the current influent process parameters include the current influent flow rate, the current influent suspended solids concentration and the current influent orthophosphate concentration;

[0118] The first calculation module 320 is used to calculate the basic dosage of PAM based on the current PAM mass concentration, the current influent flow rate, the current influent suspended solids concentration, and the current influent orthophosphate concentration; wherein the basic dosage is positively correlated with the current influent suspended solids concentration and the chemical precipitation solids load caused by the change in the current influent orthophosphate concentration;

[0119] The second calculation module 330 is used to calculate the feedback correction amount of the current PAM based on the current effluent suspended solids concentration and the current effluent total phosphorus concentration, according to the preset optimization objective function and constraints.

[0120] The control module 340 is used to determine the final dosage of PAM based on the basic dosage and the feedback correction, and to control the dosage of PAM accordingly.

[0121] Optionally, the formula for calculating the basic dosage is:

[0122] ;

[0123] In the formula, This represents the basic dosage; k1 and k2 are the PAM dosage coefficients corresponding to the influent suspended solids load; k3 represents the current influent suspended solids concentration; k3 is the PAM dosage coefficient corresponding to the phosphorus load. This represents the current orthophosphate concentration in the influent. This represents the current inflow rate; This represents the current PAM mass concentration.

[0124] Optionally, the second calculation module 330 is specifically used for: establishing a prediction model; wherein the prediction model is used to predict the effluent suspended solids concentration and the effluent total phosphorus concentration at future times based on the change sequence of PAM dosage correction; based on the prediction model, defining the optimization objective function as minimizing the sum of squared errors between the predicted effluent suspended solids concentration and the predicted effluent total phosphorus concentration at future times and their respective set target values ​​within the prediction time domain, and minimizing the fluctuation of the PAM dosage; setting constraints, including upper and lower limits of the PAM dosage, and in each control cycle, using the current effluent suspended solids concentration and the current effluent total phosphorus concentration as the initial state, resolving the PAM dosage correction sequence that satisfies the constraints and optimizes the objective function based on the prediction model, and taking the first value in the PAM dosage correction sequence as the feedback correction for the current control cycle according to the rolling optimization principle of MPC.

[0125] Optionally, the control device 300 further includes an amplification module (not shown), used to increase the PAM addition coefficients k1 and k2 corresponding to the influent suspended solids load and the PAM addition coefficient k3 corresponding to the phosphorus load in the calculation expression of the basic addition amount when the increase in the current influent suspended solids concentration or the current influent orthophosphate concentration within a preset time exceeds a preset threshold.

[0126] Optionally, the control device 300 further includes a reduction module (not shown) for multiplying the basic dosage by an energy-saving coefficient less than 1 when the current influent suspended solids concentration is detected to be lower than a preset lower limit and the current effluent suspended solids concentration and the current effluent total phosphorus concentration both meet the standards, so as to reduce the consumption of PAM reagent.

[0127] Since the apparatus described in the above embodiments of the present invention is an apparatus used to implement the methods of the above embodiments of the present invention, those skilled in the art can understand the specific structure and variations of the apparatus based on the methods described in the above embodiments of the present invention, and therefore will not be described again here. All apparatuses used in the methods of the above embodiments of the present invention fall within the scope of protection of the present invention.

[0128] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0129] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions.

[0130] It should be noted that any reference numerals placed between parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In claims that enumerate several means, several of these means may be embodied by the same hardware. The use of the terms first, second, third, etc., is merely for convenience of expression and does not indicate any order. These terms can be understood as part of the component names.

[0131] Furthermore, it should be noted that in the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0132] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims should be interpreted to include both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0133] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, then this invention should also include these modifications and variations.

Claims

1. A control method for PAM dosing of an efficient sedimentation tank, characterized in that, The control method comprises the following steps: obtaining a current PAM mass concentration and current influent process parameters; wherein the current influent process parameters comprise a current influent flow rate, a current influent suspended solids concentration and a current influent orthophosphate concentration related to phosphorus load; calculating a basic PAM dosage of the current PAM according to the current PAM mass concentration, the current influent flow rate, the current influent suspended solids concentration and the current influent orthophosphate concentration; wherein the basic PAM dosage is positively correlated with the current influent suspended solids concentration and a chemical precipitation solid load caused by a change in the current influent orthophosphate concentration; calculating a feedback correction amount of the current PAM according to a current effluent suspended solids concentration and a current effluent total phosphorus concentration based on a preset optimization objective function and constraint condition; determining a final PAM dosage of the current PAM according to the basic PAM dosage and the feedback correction amount, and controlling the dosage of PAM according to the final PAM dosage.

2. The control method according to claim 1, characterized by, The calculation expression of the basic PAM dosage is as follows: ； In the formula, represents the base dosage; k1 and k2 are PAM dosage coefficients corresponding to the influent suspended matter load; is the current influent suspended matter concentration; k3 is a PAM dosage coefficient corresponding to the phosphorus load; is the current influent orthophosphate concentration; is the current influent flow rate; is the current PAM mass concentration.

3. The control method according to claim 1, characterized by, The calculation of the feedback correction amount of the current PAM according to the current effluent suspended solids concentration and the current effluent total phosphorus concentration based on the preset optimization objective function and constraint condition comprises the following steps: establishing a prediction model; wherein the prediction model is used to predict an effluent suspended solids concentration at a future time and an effluent total phosphorus concentration at the future time according to a sequence of PAM dosage correction amount changes; defining an optimization objective function as a sum of squares of errors between a predicted effluent suspended solids concentration at a future time and a predicted effluent total phosphorus concentration at the future time and respective set target values in a prediction time domain, and minimizing fluctuations in PAM dosage, based on the prediction model; setting constraint conditions, wherein the constraint conditions comprise an upper limit and a lower limit of PAM dosage, and in each control period, taking the current effluent suspended solids concentration and the current effluent total phosphorus concentration as initial states, re-solving a sequence of PAM dosage correction amounts that satisfy the constraint conditions and make the optimization objective function optimal based on the prediction model, and taking a first value in the sequence of PAM dosage correction amounts as the feedback correction amount in the current control period according to a rolling optimization principle of MPC.

4. The control method according to claim 2, characterized by, The control method further comprises the following steps: when detecting that a rise in the current influent suspended solids concentration or the current influent orthophosphate concentration within a preset time exceeds a preset threshold, increasing PAM dosage coefficients k1 and k2 corresponding to influent suspended solids load and a PAM dosage coefficient k3 corresponding to phosphorus load in the calculation expression of the basic PAM dosage.

5. The control method according to claim 2, characterized by, The control method further comprises the following steps: when detecting that the current influent suspended solids concentration is lower than a preset lower limit and the current effluent suspended solids concentration and the current effluent total phosphorus concentration both meet the standards, multiplying the basic PAM dosage by an energy-saving coefficient less than 1 to reduce PAM agent consumption.

6. A control device for PAM dosing of an efficient sedimentation tank, characterized in that, The control method comprises the following steps: an acquisition module is configured to acquire a current PAM mass concentration and current influent process parameters; wherein the current influent process parameters comprise a current influent flow rate, a current influent suspended solids concentration and a current influent orthophosphate concentration; The first calculation module is used to calculate the basic dosage of PAM based on the current PAM mass concentration, the current influent flow rate, the current influent suspended solids concentration, and the current influent orthophosphate concentration; wherein the basic dosage is positively correlated with the current influent suspended solids concentration and the chemical precipitation solids load caused by the change in the current influent orthophosphate concentration; The second calculation module is used to calculate the feedback correction amount of the current PAM based on the current suspended solids concentration and the current total phosphorus concentration in the effluent, according to the preset optimization objective function and constraints. The control module is used to determine the final dosage of PAM based on the base dosage and the feedback correction amount, and control the dosage of PAM accordingly.

7. The control device of claim 6, wherein The formula for calculating the basic dosage is: ； In the formula, represents the base dosage; k1 and k2 are PAM dosage coefficients corresponding to the influent suspended matter load; is the current influent suspended matter concentration; k3 is a PAM dosage coefficient corresponding to the phosphorus load; is the current influent orthophosphate concentration; is the current influent flow rate; is the current PAM mass concentration.

8. The control device of claim 6, wherein The second calculation module is specifically used for: establishing a prediction model; wherein the prediction model is used to predict the effluent suspended solids concentration and the effluent total phosphorus concentration at future times based on the change sequence of PAM dosage correction; based on the prediction model, defining the optimization objective function as minimizing the sum of squared errors between the predicted effluent suspended solids concentration and the predicted effluent total phosphorus concentration at future times and their respective set target values ​​within the prediction time domain, and minimizing the fluctuation of the PAM dosage; setting constraints, including upper and lower limits for the PAM dosage, and in each control cycle, using the current effluent suspended solids concentration and the current effluent total phosphorus concentration as the initial state, resolving the PAM dosage correction sequence that satisfies the constraints and optimizes the objective function based on the prediction model, and taking the first value in the PAM dosage correction sequence as the feedback correction for the current control cycle according to the rolling optimization principle of MPC.

9. The control device of claim 7, wherein The control device further includes: The increasing module is used to increase the PAM addition coefficients k1 and k2 corresponding to the influent suspended solids load and the PAM addition coefficient k3 corresponding to the phosphorus load in the calculation expression of the basic addition amount when the increase of the current influent suspended solids concentration or the current influent orthophosphate concentration within a preset time exceeds a preset threshold.

10. The control device of claim 7, wherein The control device further includes: The reduction module is used to multiply the basic dosage by an energy-saving coefficient less than 1 when the current influent suspended solids concentration is detected to be lower than a preset lower limit and the current effluent suspended solids concentration and the current effluent total phosphorus concentration both meet the standards, so as to reduce the consumption of PAM reagent.

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