Non-intrusive sewage pH measuring method and system based on electrical impedance chromatography technology

Abstract

The invention discloses a non-intrusive sewage pH measuring method based on an electrical impedance tomography technology, which comprises the following steps of: based on an electromagnetic field theory, acquiring a sewage boundary electric signal through the electrical impedance tomography technology, establishing theoretical correlation between pH and electrode potential by combining a Nernst equation, constructing a constitutive equation, and finally, inverting a pH value by measuring the boundary electric signal, so as to measure the pH value of the sewage. Therefore, a measurement mode which does not need to intrude into a pipeline and avoids pollution and interference is realized, the defects that a traditional electrode is fragile and difficult to miniaturize, and an optical fiber sensor is easily disturbed by the environment and is complex in high-precision assembly are overcome, the influence of the complex environment of a water body is avoided, and the measurement and calculation precision of the pH is improved.

Description

Technical Field

[0001] This invention belongs to the field of pH measurement technology in sewage pipelines, and relates to a non-invasive method and system for measuring pH in sewage based on electrical impedance tomography. Background Technology

[0002] The detection of process parameters for domestic sewage quality has always been a hot research topic in the field of industrial measurement. It directly affects not only energy consumption issues such as reagent usage in subsequent domestic sewage treatment processes, but also the operation of sewage pipe networks. Among the many sewage quality parameters in sewage pipe networks, pH (Pondus Hydrogenii) is a crucial indicator. It helps researchers understand the acidity or alkalinity of the water in the pipes. The pH level not only affects coagulation, sedimentation, and filtration, thus influencing the impurity content of the water, but also the service life of the sewage pipe network. Therefore, the measurement of pH in pipe water has increasingly attracted the attention of scholars. In recent decades, researchers have conducted many active explorations in the measurement of pH in pipes, proposing a series of detection methods that have achieved good results.

[0003] Common methods for monitoring pH in pipeline wastewater include potentiometry and fiber optic detection. Potentiometry is an electrochemical analysis method that determines the concentration of an analyte based on the relationship between electrode potential and the concentration of the analyte in the solution; it is also known as the galvanic cell method. Fiber optic pH sensors are highly sensitive sensors capable of continuous and automated measurement. Due to their small size, thin structure, resistance to harsh environments, immunity to electromagnetic interference, and application in remote areas, they are superior to similar technologies in pH monitoring. However, potentiometry electrodes are fragile and cannot be miniaturized, while fiber optic detection offers high sensitivity but is easily affected by environmental changes and physical disturbances. Furthermore, the sensor fabrication process is more complex, making assembly difficult for applications requiring high precision.

[0004] To address the limitations of the aforementioned pH measurement methods, this invention proposes a novel non-invasive pH measurement method based on electrical impedance tomography (ERT). This method, grounded in electromagnetic field theory, offers advantages such as non-invasiveness, multi-parameter measurement, fast response, and visualization. Based on the principles of ERT and the conductivity characteristics of ions in solution, a constitutive equation relating pH value to the ERT boundary measurement value is derived. The feasibility of the measurement method is verified through theoretical derivation and simulated wastewater network experiments. Summary of the Invention

[0005] The purpose of this invention is to solve the problems in the prior art where the electrodes are easily damaged and difficult to miniaturize when measuring pH value by potentiometric method, and the pH value measurement by fiber optic method is easily interfered with and difficult to assemble with high precision, all of which affect the pH value test. The invention provides a non-invasive wastewater pH measurement method and system based on electrical impedance tomography.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A non-invasive wastewater pH measurement method based on electrical impedance chromatography includes the following steps: Obtain boundary measurements of the solution being tested; Establish the correlation between the pH value of the solution and the electrode potential in the test solution; Based on the correlation between solution pH and electrode potential, a constitutive equation for solution pH and boundary measurement values ​​is constructed by combining the principle of electrical impedance tomography. The pH value of the solution is calculated based on the constitutive equation and the obtained boundary measurements of the tested solution.

[0007] A further improvement of the present invention is that: The acquisition of boundary measurement values ​​of the solution under test includes: An electrical impedance tomography system is set outside the container holding the solution to be tested. The electrical impedance tomography system includes several electrode sensors. Apply an excitation electrode to any one of the electrode sensors in the electrical impedance tomography system, and measure the boundary voltage signals of the other remaining electrode sensors. Repeat this process, gradually applying an excitation electrode to each of the other electrode sensors, until all electrode sensors have been excited once. All the boundary voltage signals collected are the boundary measurement values.

[0008] The establishment of the correlation between the pH value of the solution and the electrode potential in the test solution includes: Based on the Nernst equation in electrochemistry, a quantitative relationship between the hydrogen ion activity in solution and the electrode potential is established:

[0009] Where F is the Faraday constant; R is the gas constant; and T is the absolute temperature. Let n be the standard electrode potential, and n represent the number of charges. If the oxidized state of the substance is H+, determine the values ​​of parameters F, R, T, and n to obtain: .

[0010] The constitutive equation relating the solution pH and boundary measurements is expressed by the following equation:

[0011] Among them, E F The electric potential detected for the flow field formed by the directional movement of charges; The electrode potential generated by hydrogen ions; Types of ions; The stoichiometric coefficients of the reactants in the positive electrode reaction; This is a constant, representing the standard electrode potential of 0.037V. The charge number of the ion; It is a constant, which is 0.0592 in this case.

[0012] The potential E detected in the flow field formed by the directional movement of charges F Expressed by the following formula:

[0013] The types of cations k in the solution and The following linear relationship is satisfied: E F =0.02369*(sin(k-π))-0.0001435*(k-10) 2 +0.1154 The process of constructing the constitutive equation for the solution pH value and boundary measurement values ​​includes: Based on the Nernst equation and related physical principles, construct the initial inequalities:

[0014] Where E1, E2, ..., E15 represent boundary measurement values; This represents the electric potential detected when the directional movement of charges forms a flow field. In this case, the number of electrons gained and lost at the anode and cathode is the same, and the anode reaction potential is equal to the cathode reaction potential, which is equal to the total reaction potential.

[0015] In this process, the ions in the cathode reaction are cations, let H... + The electrode potential generated by cations other than E is 其他 ,get:

[0016] in:

[0017]

[0018] in, The standard electrode potential of the first type of ion, The standard electrode potential of the k-th ion, The molar concentration of the first substance The number of charges carried by the first substance, The stoichiometric coefficient of the first substance in the positive electrode reaction. The charge number of the k-th substance, The stoichiometric coefficient of the k-th substance in the positive electrode reaction. Let be the molar concentration of the k-th substance; Based on the electrode material properties, we obtain ,get: .

[0019] A non-invasive wastewater pH measurement system based on electrical impedance chromatography technology includes: Boundary measurement value acquisition module, used to acquire boundary measurement values ​​of the solution being tested; The module for analyzing the correlation between solution pH and electrode potential is used to establish the correlation between the solution pH and electrode potential in the tested solution. The constitutive equation construction module is used to construct constitutive equations for solution pH and boundary measurements based on the relationship between solution pH and electrode potential, combined with the principle of electrical impedance tomography. The solution pH value acquisition module is used to calculate the solution pH value based on the constitutive equation and the acquired boundary measurement values ​​of the solution being tested.

[0020] A computer program product includes a computer program that, when executed by a processor, implements any one of the methods described.

[0021] A terminal device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of any of the methods described above.

[0022] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of any of the methods described herein.

[0023] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a non-invasive wastewater pH measurement method based on electrical impedance tomography (EIT). Based on electromagnetic field theory, it acquires the boundary electrical signal of wastewater using EIT, establishes a theoretical correlation between pH and electrode potential using the Nernst equation, and constructs a constitutive equation. Finally, the pH value is retrieved by measuring the boundary electrical signal. This method achieves a measurement that does not require intrusion into pipes, avoids pollution and interference, and overcomes the shortcomings of traditional methods such as fragile and difficult-to-miniaturize electrodes, susceptibility to environmental disturbances in fiber optic sensors, and complex high-precision assembly. Furthermore, it is unaffected by complex aquatic environments, thus improving the accuracy of pH measurement and calculation. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1a is a diagram illustrating the problem of electrical impedance tomography technology disclosed in the embodiments of the present invention; Figure 1b is an illustration of the inverse problem of electrical impedance tomography technology disclosed in an embodiment of the present invention; Figure 2a is a schematic diagram of the electrical impedance tomography detection system disclosed in an embodiment of the present invention; Figure 2b is a schematic diagram of the sensor array disclosed in an embodiment of the present invention; Figure 3 This is a schematic diagram of a primary battery disclosed in an embodiment of the present invention; Figure 4 This is a diagram showing the proportion of major components of soluble pollutants disclosed in an embodiment of the present invention; Figure 5a This is a diagram of the pH experimental setup used in the experiment exploring the relationship between boundary measurement values ​​and pH, as disclosed in an embodiment of the present invention. Figure 5b This is a sampling diagram of the experimental solution in the experiment exploring the relationship between boundary measurement values ​​and pH disclosed in an embodiment of the present invention; Figure 6a This is a pH error diagram of lettuce in the comparison between the actual and predicted pH values ​​of a single substance disclosed in the embodiments of the present invention. Figure 6b This is a pH error diagram of cola in the comparison between the actual and predicted pH values ​​of a single substance disclosed in the embodiments of the present invention. Figure 6c This is a diagram showing the pH error of potatoes in the comparison between the actual and predicted pH values ​​of a single substance disclosed in this embodiment of the invention. Figure 6d This is a pH error diagram of meat in the comparison between the actual and predicted pH values ​​of a single substance disclosed in an embodiment of the present invention. Figure 6e This is a pH error diagram showing the actual and predicted pH values ​​of a single substance disclosed in an embodiment of the present invention. Figure 7a This is a pH error diagram of lettuce and cola in the actual and estimated pH values ​​of the mixed substances disclosed in the embodiments of the present invention. Figure 7b This is a pH error diagram of cola meat in the actual and estimated pH values ​​of the mixed substances disclosed in the embodiments of the present invention. Figure 7c This is a pH error diagram of meat and lettuce in the actual and estimated pH values ​​of the mixed substances disclosed in the embodiments of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0032] The present invention will now be described in further detail with reference to the accompanying drawings: Referring to Figure 1, this embodiment of the invention discloses a non-invasive wastewater pH measurement method based on electrical impedance tomography (EIT). This method, grounded in electromagnetic field theory, offers advantages such as non-invasiveness, multi-parameter measurement, fast response, and visualization. Based on the principles of EIT and the conductivity characteristics of ions in solution, a constitutive equation relating pH value to the EIT boundary measurement value is derived. The feasibility of the measurement method is verified through theoretical derivation and simulated wastewater network experiments.

[0033] The purpose of this invention is to provide a non-invasive method for measuring pH values ​​inside sewage pipes, overcoming the problems of water pollution, operational complexity, and low accuracy caused by the intrusion of the measuring probe into the water body in water quality testing. To achieve the above objective, this invention proposes a novel non-invasive pH measurement method based on electrochromatography technology, the method comprising the following steps: Step 1: Measurement of solution electrical signals based on electrical impedance tomography (ERT) The mathematical foundation of electrical impedance tomography (EIT) lies in the Radon transform and inverse Radon transform, while the physical basis for constructing the mathematical model of EIT is the quasi-steady field theory in electromagnetic fields. Based on the Radon transform, inverse Radon transform, and quasi-steady field theory, EIT can be summarized as a process of solving a forward problem and an inverse problem.

[0034] like Figure 1a and Figure 1b As shown, the forward problem of electrical impedance tomography (ERT) refers to the process of solving for the distribution of electric potential and electromagnetic field within a measured field, given the distribution of electrical characteristic parameters in the measured field and applying known boundary conditions to the sensitive field. The inverse problem is the opposite process, solving for the distribution of matter within the sensitive field. The basic theory of ERT obeys Maxwell's equations, and its differential form is: (1) Where B = μH, D = εE, and J = σE. In the formula, D is the electric displacement vector, ρ is the charge density, E is the electric field strength, B is the magnetic induction intensity, H is the magnetic field strength, J is the current density vector, and μ, ε, and σ are the permittivity, permeability, and conductivity, respectively.

[0035] From the perspective of practical measurement and application, the above equations require the following assumptions: (1) The ERT sensitive field is approximately a quasi-stable field, that is, it is assumed that B / t ≈0, D / t≈0, ignoring the effects of magnetoelectricity and electromagnetism; in fact, current ERT measurement systems use low-frequency weak current excitation; therefore, the corresponding electromagnetic field is a quasi-static field; thus, constitutive relations can be established and solved by analogy with constant electric field, electrostatic field and constant magnetic field. (2) The changes in electrical parameters follow a linear relationship.

[0036] The change in the electrical parameters (conductivity, permeability, and permittivity) of any unit (pixel) in an ERT field is essentially nonlinear in relation to the measured value of the field boundary response; however, such a relationship is difficult to realize in both applied measurement and computational solutions. Therefore, it is usually assumed that the change in electrical parameters is very small and thus approximated as a linear relationship.

[0037] The ERT measurement used in this embodiment is an inverse problem solution. Known boundary conditions are applied to the sensitive field, and the content and distribution of each ion in the solution are deduced through the boundary electrical signal of the solution in the measured field.

[0038] This embodiment uses a classic 16-electrode ERT system to illustrate the measurement principle.

[0039] The electrical impedance tomography system consists of a host computer, a data acquisition system, and sensors. (See attached document.) Figure 2a This system is a single-excitation 16-electrode measurement system; see [link / reference]. Figure 2b In the measurement field Ω, the data acquisition system applies an excitation voltage "V" to electrode 1 and acquires the boundary measurement values ​​of the remaining 15 electrodes. Since there are resistors connected to the outside of the electrodes, the actual measured value is the voltage value, denoted as E_boundary. These measurement values ​​are then uploaded by the data acquisition system to the host computer for storage, which is convenient for later data analysis. The above process is repeated until all 16 electrodes are excited, resulting in 16 × 15 = 240 boundary measurement values.

[0040] Let σ be the conductivity distribution function in the measurement field Ω. According to electromagnetic field theory, for any Ω in the measurement field... The relationship between the measured values ​​σ and E at Ω follows the Poisson equation, i.e.: (2) Step 2: Analysis of the conductivity and pH characteristics of ions in the solution. The Nernst equation is a crucial equation in electrochemistry that links chemical energy to the electrode potential of a galvanic cell. This equation describes the relationship between electrode potential and ionic activity in solution, and can be used to calculate the equilibrium voltage of a given redox pair at the electrode relative to the standard potential. See also... Figure 3 The specific principles are explained as follows: For a battery reaction involving two reactants: (3) X1 and X2 are the stoichiometric coefficients of reactants and products in the positive electrode reaction, and Y1 and Y2 are the stoichiometric coefficients of reactants and products in the negative electrode reaction. ox Indicates an oxidized form, a Red The substance is reduced, and n represents the stoichiometric number of electrons gained or lost. The principle is similar for battery reactions involving three, four, or more reactants. The battery reaction (3) is split into two electrode reactions, and it is assumed that both the positive and negative electrodes undergo reduction reactions that gain electrons. The high-valence substance acts as the reactant, and the low-valence substance acts as the product. The reaction is then balanced, i.e.: (1) (2) Based on the electrode reactions at the positive and negative electrodes, write the Nernst equations for the electrode potentials at the positive and negative electrodes, respectively.

[0041] The electrode potential of the positive electrode is: (6) The electrode potential of the negative electrode is: (7) Equations (6) and (7) are the Nernst equations for the positive and negative electrode potentials, respectively, which represent the relationship between the electrode potentials and the concentrations of various substances in the reaction system under standard and non-standard conditions. This is a non-standard electrode potential; For the standard electrode potential, [ ]、[ ] represent the molar concentrations of the oxidized and reduced forms of the substance in the reduction reaction, respectively. F (96500 C / mol) is the Faraday constant, R (8.314 J / mol) is the gas constant, and T is the absolute temperature. If a gas participates in the reaction, it is expressed as the relative partial pressure (p / pθ). It should be noted that for pure solids, the concentration is "1", which can be omitted in the Nernst equation. At the same time, if the oxidized form of the substance is H+, then equation (6) can be transformed into the following: (8) Substituting the parameter values ​​into the above formula yields: (9) Equation (9) plays a crucial role in the working principle of a pH meter. It can quantitatively describe the relationship between the logarithm of hydrogen ion activity (i.e., pH value) and the electrode potential of the galvanic cell, thus making it possible to determine the pH of a solution by measuring the electrode potential.

[0042] Furthermore, based on the ERT measurement principle and the Nernst equation, this invention establishes a constitutive equation with 240 boundary measurements and solution pH, and inverts the solution pH value through the boundary measurements.

[0043] Step 3: Based on the ERT measurement principle and the conductivity characteristics of ions in the solution, derive the constitutive equation for the pH value and the boundary measurement value of ERT. Based on the Nernst equation and common sense physics, this embodiment establishes a mathematical model for electrochromatographic measurement of pH values. First, 15 boundary measurement values ​​E1, E2, ..., E15 are defined, each consisting of two parts: (1) Charges accumulate towards the excitation electrode or receiving electrode under the action of an electric field. The directional movement of charges forms a flow field, thereby detecting the potential. In this embodiment, E is used. F This represents this portion of the electric potential.

[0044] (2) The excitation electrode is positively charged, and the other receiving electrodes are negatively charged. Cations or anions accumulate at the positive and negative electrodes to form a galvanic cell and generate an electrochemical reaction, thereby detecting the electrode potential. In this embodiment, E is used. N This indicates this part of the content.

[0045] Based on the above assumptions, the following equation can be obtained: (10) According to the principle of galvanic cell reaction, the anode and cathode gain and lose the same number of electrons, the anode reaction potential equals the cathode reaction potential, and the total reaction potential equals the total reaction potential. 11 (11) Furthermore, because the ions in the cathode reaction are cations, including H+... + Ca 2+ Let H be an example. + The electrode potential generated by cations other than E is 其他 Then the above formula can also be expressed as: (12) From equations (8) and (9), it can be seen that H participates in the cathode reaction + The electrode potentials generated by other cation reactions are as follows: (13) (14) Since the electrode material is iron, Therefore, equation (14) can also be expressed as: (15) Based on prior information, we know that the dissolution time T of a substance is related to... Both pH and pH have a linear relationship, and the results can be obtained by substitution. The value of . From now on, in this embodiment, the left side of the equation will be represented by E. 边界 Therefore, equation (10) can be expressed as: (16) Among them, E F The electric potential detected in the flow field formed by the directional movement of charges can be obtained according to the law of conservation of charge: (17) Here, cations in the solution, such as H+, are used. + Ca 2+ This portion of the potential is represented by the directional movement of the electrons. Analysis shows that this potential is related to the types of cations in the solution. Calculations show that the number of cation types (k) in the solution is related to E. F The following linear relationship is approximately satisfied: E F =0.02369*(sin(k-π))-0.0001435*(k-10) 2 +0.1154 (18) Step 4: Based on the constitutive equation, propose a pH measurement method. (1) Identify the substance and determine the type of ion k, thereby obtaining E. F ; (2) Substitute the prior information into formulas (13) and (14) to obtain the result. and E N ; (3) E F and E N Substituting into the formula, we get E 边界 Relationship with pH; (4) Measure E 边界 It is worthwhile to obtain real-time pH data.

[0046] This embodiment also discloses a specific embodiment: The simulation test in this embodiment was conducted in the laboratory by simulating the types of substances in a sewage pipe to explore the relationship between boundary measurements and pH, verify the accuracy of the model, and thus prove the feasibility of the proposed method.

[0047] Based on prior information, the soluble pollutants in the sewage pipes mainly fall into five categories: leafy vegetables, root vegetables, meat scraps, staple foods, and inorganic pollutants, accounting for 38.65%, 15.13%, 8.45%, 3.09%, and 34.67% respectively. Figure 4As shown in the figure. In order to simulate the environment inside a sewage pipe, this embodiment selects one common substance from each of the five categories as a representative, and prepares the substance according to the proportion of each component in the sewage pipe. The substances are 212g of lettuce, 83g of potato, 50g of meat, 17g of rice, and 190g of cola. These substances are then put into a simulated pipe filled with tap water for the experiment.

[0048] All experiments used the ERT system developed in the laboratory. For example... Figure 5a and Figure 5b As shown, 16 electrodes are uniformly installed in a cylindrical container simulating a sewage pipe. The sampling rate of the ERT system is 25 sets / second, and each set obtains 15*16=240 measurement values. These measurement values ​​will be transmitted to the host computer for storage. In order to avoid noise interference and bad values ​​caused by measurement errors, this embodiment will take the average of the 240*n sets of data as the boundary measurement true value for the experiment.

[0049] The experiment investigates the functional relationship between boundary measurement values ​​and pH, and mainly consists of two parts: (1) Establishment and verification of the relationship between the boundary measurement value of a single substance and the pH value; (2) Establishment and verification of the relationship between boundary measurements of the mixture and pH value; When measuring the functional relationship of pH value, the ion type K needs to be determined according to the steps in Table 1. Here, based on prior information, the types of ions generated after the substances used in the experiment are dissolved in water are summarized in the following table: Table 1. Types of ions in the impurity solution

[0050] Establishment and verification of the relationship between boundary measurements and pH value: First, a single substance Following the steps in Table 1, this embodiment uses lettuce as an example to illustrate how to establish a functional relationship between boundary measurement values ​​and pH values. To simulate the dissolution process of kitchen waste in sewage pipes, 212g of cooked lettuce was crushed using a blender and poured into a measuring field containing tap water. The solution was stirred for 20 minutes using a magnetic stirrer and then stopped. After the solution settled, boundary measurement values ​​were collected using an ERT device. Then, 25ml of the solution was measured in a test tube to measure the pH value. The above stirring and data collection process was repeated eight times to obtain eight sets of experimental data. These eight sets of data can basically cover the entire process of lettuce residue dissolving in water. Next, the eight sets of data are divided into two parts. The first part of four sets serves as prior information to identify the coefficients in the expression, and the second part of the last four sets is used to verify the validity of the expression.

[0051] (1) Expression creation According to Table 1, the number of ions in lettuce is K=8. Substituting this into equation (18), we can obtain... =0.1042 Based on the four sets of prior information values, we can obtain... =0.1333T-1.419 Will , Substituting K into equation (16) yields: = + =-0.0085 2 +0.1153 -0.2535 Furthermore, the expressions for cola, potatoes, meat, and rice can be obtained as follows: =-0.0014 2 +0.0152 +0.0557 =-0.0014 2 +0.0182 +0.0368 =0.0033 2 -0.0412 +0.2244 =0.002 2 -0.0266 +0.1805 (2) Data validation Figure 6a , Figure 6b , Figure 6c , Figure 6d and Figure 6e The estimated values ​​of pH for lettuce, cola, potatoes, meat, and rice are plotted on the same graph as their actual values. Table 2 shows the error between the estimated and actual pH values. Table 2. pH value error table for a single substance

[0052] Analysis of Figure 6 shows that the estimated pH values ​​of the five substances generally follow the same trend as the actual values. Except for the second estimated value in Figure 6a and... Figure 6dThe fourth estimated value was obtained, while the estimated values ​​for other measurement points almost coincided with the actual values. Table 2 shows that the average error rates for the five substances were 0.1919%, 0.0715%, 0.2270%, 0.2108%, and 0.1305%, respectively. For lettuce, except for the second point, the error range was [0.0660%, 0.1382%], with the 0.4574% error at the second point possibly due to the solution not being completely still during measurement or measurement error. For cola, the error range was [0.0071%, 0.1252%], with no outliers compared to the average. For potatoes, the error range was [0.1699%, 0.2701%], with no outliers compared to the average. For meat, except for the fourth point, the error range was [0.0305%, 0.2057%], with the 0.4264% error at the fourth point possibly due to slight saturation of the substance in the water. Except for the fourth point, the error range for the rice samples is [0.0160%, 0.0986%]. The 0.3582% error in the fourth point may be due to slight saturation of the substance in the water. Overall, the estimated values ​​have good consistency with the actual values, and the errors are all within three decimal places, proving that the method is effective.

[0053] Second, mixtures 212g of lettuce, 190g of cola, and 50g of meat were chopped and mixed in pairs. Data were collected following the experimental procedure for studying a single substance. The derivation of the expression was the same as for a single substance. The relationship between the boundary measurement values ​​and pH values ​​of the pairwise mixtures of lettuce and cola, cola and meat, and meat and lettuce is as follows: Lettuce and Coke: =0.0052 2 -0.0688 +0.3680 Cola Meat: =0.0588 2 -0.7933 +2.7535 Meat and lettuce: =-0.005 2 +0.0748 +0.0557 Figure 7a , Figure 7b and Figure 7c The estimated values ​​of lettuce with cola, cola with meat, and meat with lettuce are plotted on the same graph as their actual values. Table 3 shows the error between the estimated and actual pH values.

[0054] Table 3 pH value error table for mixed substances

[0055] Analysis of Figure 7 shows that the estimated pH values ​​of the three mixtures generally follow the same trend as the actual values. Except... Figure 7c The fourth estimated value was obtained, while the estimated values ​​at other measurement points almost perfectly matched the actual values. Table 3 shows that the average error rates for the three substances were 0.1165%, 0.0663%, and 0.2565%, respectively. The error range for lettuce + cola was [0.0442%, 0.2467%], with no outliers compared to the average. The error range for cola + meat was [0.0147%, 0.1329%], with no outliers compared to the average. For lettuce + meat, except for the fourth point, the error range was [0.1124%, 0.2546%]. The 0.4241% error at the fourth point might be due to slight saturation of the substance in water. Overall, the estimated values ​​showed good correlation with the actual values, and the errors were all within two decimal places, proving the method's effectiveness.

[0056] This invention discloses a non-invasive wastewater pH measurement system based on electrical impedance chromatography, comprising: Boundary measurement value acquisition module, used to acquire boundary measurement values ​​of the solution being tested; The module for analyzing the correlation between solution pH and electrode potential is used to establish the correlation between the solution pH and electrode potential in the tested solution. The constitutive equation construction module is used to construct constitutive equations for solution pH and boundary measurements based on the relationship between solution pH and electrode potential, combined with the principle of electrical impedance tomography. The solution pH value acquisition module is used to calculate the solution pH value based on the constitutive equation and the acquired boundary measurement values ​​of the solution being tested.

[0057] The method disclosed in this invention can achieve non-invasive measurement without entering the pipeline, thus not affecting the aquatic environment or being interfered with by the water body, and has high measurement stability. This method is based on mechanism modeling and derives mathematical equations, resulting in high measurement accuracy.

[0058] A schematic diagram of a terminal device according to an embodiment of the present invention. The terminal device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the various method embodiments described above. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the various device embodiments described above.

[0059] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.

[0060] The terminal device can be a desktop computer, laptop computer, cloud server, or other device with strong computing power. The terminal device may include, but is not limited to, a processor and memory.

[0061] The optimal choice for the processor is a multi-core high-speed central processing unit (CPU).

[0062] The memory can be used to store the computer program and / or module. The processor implements various functions of the terminal device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0063] If the modules / units integrated into the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0064] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A non-invasive sewage pH measurement method based on electrical impedance tomography technology, characterized in that, The method comprises the following steps: obtaining boundary measurement values of the measured solution; establishing a correlation between the solution PH value and the electrode potential in the measured solution; constructing a constitutive equation of the solution PH value and the boundary measurement values based on the correlation between the solution PH value and the electrode potential and combining the electrical impedance tomography measurement principle; calculating the solution PH value based on the constitutive equation and the obtained boundary measurement values of the measured solution.

2. The non-invasive wastewater pH measurement method based on electrical impedance tomography technique according to claim 1, characterized in that, The step of obtaining the boundary measurement values of the measured solution comprises: arranging an electrical impedance tomography measurement system outside a container in which the measured solution is placed, the electrical impedance tomography measurement system comprising a plurality of electrode sensors; applying an excitation electrode to any one of the electrode sensors in the electrical impedance tomography measurement system, measuring the boundary voltage signals of the remaining electrode sensors, and repeating the step to apply an excitation electrode to each of the other electrode sensors until all the electrode sensors are excited once, and collecting all the boundary voltage signals as the boundary measurement values.

3. The non-invasive wastewater pH measurement method based on electrical impedance tomography technique according to claim 1, characterized in that, The step of establishing the correlation between the solution PH value and the electrode potential in the measured solution comprises: establishing a quantitative relationship between the hydrogen ion activity and the electrode potential in the solution according to the Nernst equation in electrochemistry: where F is Faraday's constant; R is the gas constant; and T is the absolute temperature; is the standard electrode potential, and n represents the number of charges carried; if the oxidized species is H+, the values of the parameters F, R, T, and n are determined, and the following is obtained: 。 4. The non-invasive wastewater pH measurement method based on electrical impedance tomography technique according to claim 3, characterized in that, The constitutive equation of the solution PH value and the boundary measurement values is expressed by the following formula: where E F is the potential detected by the flow field of the directed movement of charges; is the electrode potential generated by hydrogen ions; is the ion species; is the stoichiometric number of reactants in the positive electrode reaction; is a constant; is the number of charges carried by the ion; is a constant.

5. The non-invasive wastewater pH measurement method based on electrical impedance tomography technique according to claim 4, characterized in that, The electric potential E detected by the flow field formed by the directed movement of electric charges F is expressed by the following formula: The cationic species k in solution and satisfy the following linear relationship: E F = 0.02369 * (sin(k - π)) - 0.0001435 * (k - 10) 2 + 0.1154.

6. The non-invasive wastewater pH measurement method based on electrical impedance tomography technique according to claim 4, characterized in that, The construction process of the constitutive equation of the solution PH value and the boundary measurement values comprises: constructing an initial inequality according to the Nernst equation and related physical principles: wherein E1, E2,..., E15 represent boundary measurements; represents the potential detected when the directed movement of charges forms a flow field; wherein the number of electrons lost and gained by the anode and the cathode is the same, and the anode reaction potential is equal to the cathode reaction potential, which is equal to the total reaction potential, i.e. wherein the ions of the cathode reaction are cations, and let H + be the electrode potential generated by cations other than H 其他 , and we obtain: wherein: wherein E0,1 is the standard electrode potential of the first ion, E0,k is the standard electrode potential of the kth ion, c1 is the molar concentration of the first substance, z1 is the number of charges carried by the first substance, n1 is the stoichiometric number of the first substance in the anodic reaction, zk is the number of charges carried by the kth substance, nk is the stoichiometric number of the kth substance in the anodic reaction, ck is the molar concentration of the kth substance; According to the electrode material properties, we get , we get: 。 7. A non-invasive sewage pH measurement system based on electrical impedance tomography technology, characterized in that, comprises: a boundary measurement value acquisition module configured to obtain the boundary measurement values of the measured solution; a solution PH value and electrode potential correlation analysis module configured to establish the correlation between the solution PH value and the electrode potential in the measured solution; a constitutive equation construction module configured to construct the constitutive equation of the solution PH value and the boundary measurement values based on the correlation between the solution PH value and the electrode potential and combining the electrical impedance tomography measurement principle; a solution PH value acquisition module configured to calculate the solution PH value based on the constitutive equation and the obtained boundary measurement values of the measured solution.

8. A computer program product comprising a computer program, characterized in that, The computer program is executed by the processor to implement the method of any one of claims 6-7.

9. A terminal device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program to implement the steps of the method of any one of claims 6-7.

10. A computer-readable storage medium storing a computer program, the computer-readable storage medium comprising: The computer program is executed by the processor to implement the steps of the method of any one of claims 6-7.

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