A high-precision UVCOD measurement method and measurement system based on three-dimensional coordinate system scanning

Abstract

The present invention discloses a high-precision UVCOD measurement method and measurement system based on three-dimensional coordinate system scanning, which establishes a three-dimensional coordinate system in the three-dimensional space to be measured. xyz Coordinate system, respectively, using multi-band turbidity compensation UVCOD measuring instrument scanning measurement now Coordinate plane and summer Coordinate plane, and obtain gridded detection data; based on now Coordinate plane and summer The detection concentration in three-dimensional space is calculated from the plane or single-dimensional detection data of the coordinate plane C UVCOD The UVCOD measuring instrument based on multi-band turbidity compensation of the present invention scans and measures the UVCOD of adjacent planes, further increasing the accuracy of single-point UVCOD data measurement. now Coordinate plane and summer The detection data of the coordinate plane is used to calculate the detection concentration in the three-dimensional space that reflects the overall measurement situation. C UVCOD It meets the high-precision requirements of UVCOD measurement in three-dimensional space, solves the limitations of single-point measurement, and has good practicality.

Description

Technical Field

[0001] The present invention belongs to the technical field of water quality detection, and in particular relates to a high-precision UVCOD measurement method and a measurement system based on three-dimensional coordinate system scanning. Background Art

[0002] Online COD detection typically includes potassium dichromate colorimetry, non-dispersive infrared absorption (TOC), and ultraviolet (UV) methods. Existing technologies generally use the UV method to characterize water COD. Specific dissolved organic matter in a water sample strongly absorbs ultraviolet light of a specific wavelength. The absorbance is measured and then converted to a COD value through correlation. This method is particularly suitable for water bodies free of suspended particles, with stable composition, and colorless and transparent. Ultraviolet-visible absorption spectroscopy (UVCOD) is an electronic absorption spectrum generated by transitions of the outer electrons or valence electrons of polyatomic molecules. The electron energy level interval typically ranges from 1 to 20 eV, which falls well within the UV-visible region. Each transition between electronic energy levels is accompanied by changes in the molecular vibrational and rotational energy levels. Consequently, the absorption lines of these electronic transitions become broad bands that encompass the fine molecular vibrational and rotational structure. This type of spectrum can be used for the analysis and study of compounds containing unsaturated bonds, particularly those containing conjugated systems.

[0003] There are many types of organic pollutants in water, including humic substances (such as humic acid and fulvic acid, which are formed by the decomposition of plant residues and have complex aromatic structures and conjugated double bonds), which are common macromolecular organic substances in natural water bodies; aromatic compounds with UV-absorbing properties (including benzene series, phenols, and polycyclic aromatic hydrocarbons (PAHs), which are commonly found in industrial and domestic wastewater); proteins and carbohydrates derived from animal and plant metabolites and human activities, which are easily degraded by microorganisms but can increase the COD value of water bodies at high concentrations; and oil and fat pollutants commonly found in industrial wastewater, including animal and plant oils and petroleum. In our UVCOD monitoring work at water plants, we pay special attention to organic substances with UV-absorbing properties that pose a significant threat to water quality safety. These organic substances mainly include: humic acid and fulvic acid, which are the main components of natural organic matter (NOM), which may promote the formation of disinfection by-products (such as trihalomethanes) and affect the safety of drinking water; phenolic compounds with strong ultraviolet absorption, which may come from industrial wastewater or non-point source pesticide pollution; some carcinogenic benzene series and polycyclic aromatic hydrocarbons (PAHs), whose concentrations need to be strictly controlled; and disinfection by-product precursors that are easily converted into harmful substances during chlorine disinfection, especially those containing conjugated structures.

[0004] However, when testing the chemical oxygen demand of water sources, turbidity will cause the light transmittance of the water sample to decrease, and suspended particles or suspended matter in the water may adsorb the chemical oxygen demand reagent, which will affect the results of the chemical oxygen demand test. In complex scenarios, especially in high turbidity environments, the colloids, suspended matter, flocs and other substances that produce turbidity in water are of various types and complex in composition. The values ​​of the Mie scattering factor and the chromaticity influencing factor will change with the different components of the water body. The maximum error of the ultraviolet (UV) method can exceed 50% when the water quality is relatively complex. Therefore, turbidity compensation is required, and monochromatic light of different bands (array compensation light source) is needed to eliminate the influence, eliminate the interference of turbidity on optical measurement and reagent reaction, and improve the reliability and accuracy of chemical oxygen demand detection.

[0005] For example, the ultraviolet absorption method (UV254) uses a wavelength of 254nm as the measurement light source. Its core mechanism is that most soluble organic matter (especially aromatic compounds containing structures such as conjugated double bonds and benzene rings) exhibit a strong absorption peak at this wavelength, and the absorbance is linearly related to the concentration. For example, large molecular organic matter such as humic acid and lignin has a stable absorption value that is suitable as a substitute for COD. In order to eliminate the interference of non-organic matter such as turbidity and suspended matter, this method uses dual-wavelength or multi-band measurement technology, with 254nm as the measurement wavelength and 550nm or 860nm as the reference wavelength (multi-band can be subdivided and selected according to the actual water body) to achieve interference compensation by comparing changes in light intensity. In addition, this method does not require chemical reagents, reduces secondary pollution, and can achieve real-time online monitoring with a response speed as fast as seconds.

[0006] Secondly, existing UVCOD sensors use a single-point detection method, which has obvious spatial limitations. Traditional fixed UVCOD sensors, such as pipe-embedded or submerged probes, can only obtain local data from water bodies. Due to their limited monitoring range, it is difficult to capture the three-dimensional spatial COD gradient changes in the water body caused by factors such as suspended particle sedimentation, turbulent disturbances, or pollutant diffusion. Taking rivers as an example, when the distribution of microorganisms in different layers of water bodies is different, the COD difference between the surface and deep layers of the water body is significant. At this time, the data obtained by single-point detection can easily lead to misjudgment of the overall water quality. On the other hand, the concentration of water bodies is affected by a combination of factors such as flow rate, temperature, and biological activity, showing dynamic uneven characteristics. Existing UVCOD sensors are difficult to achieve continuous monitoring in vertical stratification or horizontal gridding, and thus cannot fully and accurately reflect the dynamic changes of COD in water bodies. Summary of the Invention

[0007] The purpose of the present invention is to provide a high-precision UVCOD measurement method and measurement system based on three-dimensional coordinate system scanning. The multi-band turbidity compensation method is used for UVCOD measurement, which reduces the influence of turbidity on single detection data. The detection concentration in three-dimensional space is calculated by the detection data of adjacent xoz coordinate planes and yoz coordinate planes, aiming to overcome the limitations of single-point measurement and significantly improve the detection accuracy of the space to be measured.

[0008] The present invention is mainly achieved through the following technical solutions:

[0009] A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning includes the following steps:

[0010] Step T1: Establish a three-dimensional xyz coordinate system in the three-dimensional space to be measured;

[0011] Step T2: using a multi-band turbidity compensation UVCOD measuring instrument to scan and measure the xoz coordinate plane and the yoz coordinate plane, and obtaining gridded detection data;

[0012] Step T3: Based on the plane or single-dimensional detection data of the xoz coordinate plane and the yoz coordinate plane, calculate the detection concentration C in three-dimensional space UVCOD .

[0013] Preferably, the UVCOD measuring instrument performs spatial scanning measurement based on Cartesian coordinates.

[0014] In order to better implement the present invention, further, step T3 includes the following steps:

[0015] Step A1: Based on the plane detection data of the xoz coordinate plane, calculate the UVCOD average value of the xoz coordinate plane

[0016] Step A2: Based on the plane detection data of the yoz coordinate plane, calculate the UVCOD average value of the yoz coordinate plane

[0017] Step A3: Based on steps A1 and A2, calculate the detection concentration C in three-dimensional space UVCOD for:

[0018]

[0019] in:

[0020]

[0021] Where: w xoz is the UVCOD weighting coefficient of the xoz coordinate plane;

[0022] w yoz is the UVCOD weighting coefficient of the yoz coordinate plane;

[0023] is the UVCOD mean deviation in the xoz coordinate plane;

[0024] is the average UVCOD deviation in the yoz coordinate plane.

[0025] In order to better implement the present invention, further, in step A1, the UVCOD average value of the xoz coordinate plane for:

[0026]

[0027] In step A2, the UVCOD average value of the yoz coordinate plane for:

[0028]

[0029] Where: l is the number of subdivision steps on the x-axis;

[0030] m is the number of subdivision steps on the y-axis;

[0031] n is the number of subdivision steps on the z axis;

[0032] C ij It is the detection data corresponding to the xoz coordinate plane or the yoz coordinate plane.

[0033] In order to better implement the present invention, further, in step A3, the uncertainty u caused by the plane detection data measurement is UVCOD for:

[0034]

[0035] In order to better implement the present invention, further, step T3 includes the following steps:

[0036] Step B1: Based on the detection data of the x dimension of the xoz coordinate plane, calculate the concentration value C of the xoz coordinate plane xoz :

[0037]

[0038] Where: w xi is the weighting coefficient of the i-th x dimension of the xoz coordinate plane;

[0039] is the single-dimensional UVCOD scan average value of the xoz coordinate plane;

[0040] n is the number of subdivision steps on the z axis;

[0041] Step B2: Based on the detection data of the y dimension of the yoz coordinate plane, calculate the concentration value C of the yoz coordinate plane yoz :

[0042]

[0043] Where: w yi is the weighting coefficient of the i-th y dimension of the yoz coordinate plane;

[0044] is the single-dimensional UVCOD scan average value of the yoz coordinate plane;

[0045] Step B3: Based on steps B1 and B2, calculate the detection concentration C in three-dimensional space UVCOD for:

[0046]

[0047] In order to better implement the present invention, further, in step B3, the uncertainty u caused by the measurement of the detection data based on the x dimension and the y dimension is UVCOD for:

[0048]

[0049] in:

[0050]

[0051] Where: u xoz is the concentration value C on the xoz coordinate plane xoz uncertainty;

[0052] u yoz is the concentration value C on the yoz coordinate plane yoz uncertainty.

[0053] In order to better implement the present invention, further, in step T2, the detection concentration of the UVCOD measuring instrument using multi-band turbidity compensation is:

[0054]

[0055] Among them: A 254 is the absorbance measured by UV254;

[0056] The wavelength is λ i The absorbance corresponding to the turbidity compensation light;

[0057] The wavelength is λ i The turbidity compensation coefficient corresponding to the turbidity compensation light;

[0058] r is the type of monochromatic light turbidity compensation light;

[0059] b is the optical path or solution thickness;

[0060] ε UVCOD It is the equivalent UV254 molar absorptivity, or the calibrated molar absorptivity coefficient.

[0061] In order to better realize the present invention, further, the detection concentration of the UVCOD measuring instrument using 550nm and 890nm dual-band turbidity compensation is:

[0062]

[0063] Among them: A 550 The absorbance is compensated for turbidity at 550 nm.

[0064] A 890 The absorbance is compensated for turbidity at 890 nm;

[0065] k 550 is the turbidity compensation coefficient of 550nm band;

[0066] k 890 It is the turbidity compensation coefficient of 890nm band.

[0067] In order to better implement the present invention, further, the determination of the turbidity compensation coefficient includes the following steps:

[0068] Step S1: preparing a standard turbidity solution using hexamethylenetetramine and hydrazine sulfate, and preparing a standard COD solution using potassium hydrogen phthalate;

[0069] Step S2: using a standard turbidity solution and a standard COD solution, a mixed solution with the same turbidity but different COD is prepared; measuring the absorbance of the 254 nm band and the absorbance of each compensation band;

[0070] The absorbance measured at 254 nm is:

[0071]

[0072] Among them: A (254)n is the absorbance measured at 254 nm of the nth group of mixed solutions;

[0073] The absorbance measured in each compensation band is:

[0074]

[0075] Among them: A Sn is the λ of the nth mixed solution r The UVCOD measured in the compensation band is converted to the corresponding absorbance;

[0076] is the λ of the nth mixed solution r absorbance measured in the compensation band;

[0077] Step S3: Establish the turbidity compensation coefficient matrix for each compensation band:

[0078]

[0079] Where: k s =0;

[0080] is λ r Turbidity compensation coefficient of compensation band;

[0081] Through matrix operations we get:

[0082] W=(X T X) -1 X T y;

[0083] Step S4: Change the turbidity and repeat steps S2-S3; wherein the absorbance corresponding to the solutions with different turbidity is:

[0084]

[0085] Among them: A sn is the absorbance corresponding to the nth group of turbidity solutions;

[0086] The turbidity compensation coefficients of each compensation band corresponding to different turbidity solutions are:

[0087]

[0088] The piecewise linear relationship between the turbidity compensation coefficient and absorbance of each compensation band is obtained as follows:

[0089]

[0090] Step S5: The formula for obtaining the turbidity compensation coefficient and the corresponding absorbance of each compensation band by polynomial fitting is:

[0091] k λ =z n x n +…+z2x 2 +z1x+e,

[0092] Where: x is the absorbance measured corresponding to the compensation band light source;

[0093] z n is the n-th power fitting coefficient of the λ band;

[0094] e is the constant term of the fitting.

[0095] In order to better implement the present invention, further, when using 550nm and 890nm dual-band turbidity compensation, the turbidity compensation coefficients of the 550nm and 890nm bands are respectively:

[0096] k 550 =a n x n +…+a2x 2 +a1x+c,

[0097] k 890 =b n x n +…+b2x 2 +b1x+d,

[0098] Among them: a n and b n are the n-th power fitting coefficients of the 550nm band and the 890nm band respectively;

[0099] c and d are both constant terms of the fitting.

[0100] The present invention is mainly achieved through the following technical solutions:

[0101] A high-precision UVCOD measurement system based on stereo coordinate system scanning is based on the above-mentioned high-precision UVCOD measurement method based on stereo coordinate system scanning, comprising a UVCOD measuring instrument and a data processing unit. The UVCOD measuring instrument comprises a 254nm light source, a compensation light source array, and a detector module. The detector module is used to obtain the intensity of the transmitted light of the 254nm light source and the compensation light source array.

[0102] The data processing unit includes a UVCOD compensation processing unit, a three-dimensional data acquisition unit, a plane processing unit and a single-dimensional processing unit;

[0103] The compensation UVCOD processing unit is used to obtain UVCOD measurement data using multi-band turbidity compensation;

[0104] The three-dimensional data acquisition unit is used to collect gridded detection data of three-dimensional scanning;

[0105] The plane processing unit is used to calculate the detection concentration C in the three-dimensional space based on the detection data of the xoz coordinate plane and the yoz coordinate plane. UVCOD ;

[0106] The single-dimensional processing unit is used to calculate the detection concentration C in the three-dimensional space based on the single-dimensional detection data of the xoz coordinate plane and the yoz coordinate plane. UVCOD .

[0107] The beneficial effects of the present invention are as follows:

[0108] The present invention obtains gridded detection data of adjacent xoz coordinate planes and yoz coordinate planes through plane scanning measurement of the UVCOD measuring instrument, and calculates the detection concentration C in three-dimensional space based on the plane detection data or single-dimensional detection data. UVCOD , which effectively improves the accuracy of UVCOD measurement, solves the limitations of single-point measurement, and has good practicality.

[0109] The present invention uses a multi-band turbidity compensation method for UVCOD measurement, further increasing the accuracy of single-point UVCOD data measurements. Furthermore, the turbidity compensation coefficient obtained through fitting can be dynamically adjusted based on the absorbance of the corresponding compensation wavelength, further accounting for dynamic changes in the monitoring environment and significantly improving the accuracy of compensation.

[0110] The present invention processes the UVCOD data of the xoz coordinate plane and the yoz coordinate plane by a plane calculation method, and can quickly calculate the detection concentration C in the three-dimensional space reflecting the overall measurement situation. UVCOD On the other hand, the present invention can process the UVCOD data of the xoz coordinate plane and the yoz coordinate plane by a single-dimensional calculation method, and can more accurately calculate the detection concentration C in the three-dimensional space. UVCOD , which meets the high-precision requirements of UVCOD measurement in three-dimensional space and has good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0111] Figure 1 This is the principle block diagram of the UVCOD measuring instrument with multi-band turbidity compensation;

[0112] Figure 2 This is a flow chart of the high-precision UVCOD measurement method based on three-dimensional coordinate system scanning in Example 1;

[0113] Figure 3 Flow chart of the high-precision UVCOD measurement method based on three-dimensional coordinate system scanning in Example 2;

[0114] Figure 4 This is a principle block diagram of the high-precision UVCOD measurement system based on three-dimensional coordinate system scanning of the present invention. DETAILED DESCRIPTION

[0115] Example 1:

[0116] A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning is proposed. A three-dimensional xyz coordinate system is established in the three-dimensional space to be measured. A multi-band turbidity compensation UVCOD measuring instrument is used to scan and measure the xoz coordinate plane and the yoz coordinate plane, and gridded detection data are obtained. The detection concentration C in the three-dimensional space is calculated based on the plane detection data of the xoz coordinate plane and the yoz coordinate plane. UVCOD .like Figure 2 As shown, the specific steps include:

[0117] Step 1: Data Scan:

[0118] The UVCOD measuring instrument is used to perform step-by-step plane scanning. The plane scanning process first performs the x-axis motion scanning process, then the y-axis motion scanning process, then moves the z-axis, and then repeats the plane scanning.

[0119] The xoz coordinate plane scanning data is obtained through spatial scanning:

[0120]

[0121] Obtain YOZ coordinate plane scanning data through spatial scanning:

[0122]

[0123] Where: l is the number of subdivision steps on the x-axis;

[0124] m is the number of subdivision steps on the y-axis;

[0125] n is the number of subdivision steps on the z-axis.

[0126] Step 2: Calculate the detection concentration C in three-dimensional space UVCOD :

[0127] UVCOD uses the plane calculation method to calculate the detection concentration C UVCOD : Calculate all the data in the plane and calculate the arithmetic mean, standard deviation, average deviation, weighting coefficient and the detection concentration C in three-dimensional space in turn UVCOD .

[0128] Step A1: Calculate the UVCOD average value of the xoz coordinate plane based on the plane detection data of the xoz coordinate plane

[0129] 1) Calculate the arithmetic mean of UVCOD scan data in the xoz coordinate plane:

[0130]

[0131] C ijis the detection data of the xoz coordinate plane or the yoz coordinate plane, C ij∈ C nl ;

[0132] i and j are process data and have no practical meaning;

[0133] l is the subdivision on the x-axis;

[0134] n is the number of subdivision steps on the z-axis.

[0135] 2) Calculate the standard deviation:

[0136]

[0137] Where: xoz is the standard deviation of UVCOD in the xoz coordinate plane;

[0138] is the arithmetic mean of UVCOD scanning data in the xoz coordinate plane;

[0139] C ij is the process operation data, C ij∈ C nl ;

[0140] ij is process data and has no practical meaning;

[0141] l is the number of subdivision steps on the x-axis;

[0142] n is the number of subdivision steps on the z axis;

[0143] 3) Calculate the average deviation:

[0144]

[0145] Where: xoz is the standard deviation of UVCOD in the xoz coordinate plane;

[0146] is the average deviation of UVCOD in the xoz coordinate plane;

[0147] l is the number of subdivision steps on the x-axis;

[0148] n is the number of subdivision steps on the z-axis.

[0149] Step A2: Calculate the UVCOD average value of the yoz coordinate plane based on the plane detection data of the yoz coordinate plane

[0150] 1) Calculate the arithmetic mean of UVCOD scanning data in the yoz coordinate plane:

[0151]

[0152] Where: C ij is the process operation data, C ij∈ C mn ;

[0153] The ij process data has no practical meaning;

[0154] m is the number of subdivision steps on the y-axis;

[0155] n is the number of subdivision steps on the z-axis.

[0156] 2) Calculate the standard deviation:

[0157]

[0158] 3) Calculate the average deviation:

[0159]

[0160] Calculation method of weighting coefficient:

[0161]

[0162] w xoz is the weighting coefficient of turbidity in the xoz coordinate plane;

[0163] w yoz is the weighting coefficient of turbidity in the yoz coordinate plane.

[0164] Step A3: Based on steps A1 and A2, calculate the detection concentration C in three-dimensional space UVCOD :

[0165]

[0166] Step 3: Weighted average uncertainty assessment:

[0167]

[0168] u UVCOD Uncertainty caused by measurement (Class A).

[0169] Example 2:

[0170] A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning is proposed. A three-dimensional xyz coordinate system is established in the three-dimensional space to be measured. A multi-band turbidity compensation UVCOD measuring instrument is used to scan and measure the xoz coordinate plane and the yoz coordinate plane, and gridded detection data is obtained. The detection concentration C in the three-dimensional space is calculated based on the single-dimensional detection data of the xoz coordinate plane and the yoz coordinate plane. UVCOD .like Figure 3As shown, the specific steps include:

[0171] Step 1: Data scanning is the same as that described in Example 1, so it will not be repeated here.

[0172] Step 2: Calculate the detection concentration C using a single-dimensional calculation method UVCOD , use the detection data of x-axis and y-axis to perform subdivision calculation, and then perform overall calculation. The specific steps are: complete the single-dimensional calculation arithmetic mean, standard deviation, average deviation, and weighting coefficient in sequence; perform comprehensive calculation on different single-dimensional data to obtain the detection concentration C in three-dimensional space UVCOD .

[0173] The single-dimensional calculation model is:

[0174] 1. Calculate the arithmetic mean

[0175]

[0176] Where: g is the number of subdivision steps in a single dimension, g∈{lm};

[0177] It is the arithmetic mean obtained from a single scan of a single dimension;

[0178] C i Calculates data for the subdivision measurement process of single-dimensional scanning, C i ∈C nl ∪C nm ;

[0179] i is process data and has no practical meaning.

[0180] 2. Calculate the standard deviation

[0181]

[0182] Where: g is the standard deviation of turbidity in a single dimension.

[0183] 3. Calculate the average deviation

[0184]

[0185] in: is the average deviation of turbidity in a single dimension.

[0186] 4. Single dimension weighting coefficient

[0187]

[0188] Preferably, the specific steps of the one-dimensional calculation method are as follows:

[0189] Step B1: Based on the detection data of the x dimension of the xoz coordinate plane, calculate the concentration value C of the xoz coordinate plane xoz :

[0190] (1) The x-dimensional data on the xoz coordinate plane is obtained through the unit dimension calculation model:

[0191] Calculate the arithmetic mean as:

[0192]

[0193] The standard deviation is:

[0194] [σ 1x σ 2x … σ nx ]

[0195] The weighting coefficient is:

[0196] [w 1x w 2x … w nx ]

[0197] (2) The y-dimensional data on the yoz coordinate plane is obtained through the unit dimension calculation model:

[0198] The arithmetic mean is:

[0199]

[0200] The standard deviation is:

[0201] [σ 1y σ 2y … σ ny ]

[0202] Weighting coefficient:

[0203] [w 1y w 2y … w ny ]

[0204] (3) Calculate the concentration value C on the xoz coordinate plane xoz :

[0205] 1) UVCOD data:

[0206]

[0207] Where: w xi is the weighting coefficient of the i-th x dimension of the xoz coordinate plane;

[0208] C xoz is the concentration value of the xoz coordinate plane;

[0209] n is the number of subdivision steps on the z-axis.

[0210] is the single-dimensional UVCOD scan average value of the xoz coordinate plane,

[0211] 2) Uncertainty data:

[0212]

[0213] Where: u xoz is the concentration value C on the xoz coordinate plane xoz uncertainty;

[0214] For the yoz coordinate plane, the processing is as follows:

[0215] Step B2: Based on the detection data of the y dimension of the yoz coordinate plane, calculate the concentration value C of the yoz coordinate plane yoz :1) UVCOD data:

[0216]

[0217] Where: C yoz is the concentration value of the yoz coordinate plane;

[0218] w yi is the weighting coefficient of the i-th y dimension of the yoz coordinate plane, w yi ∈w yn ;

[0219] Single-dimensional UVCOD scan average value of the yoz coordinate plane,

[0220] n is the number of subdivision steps on the z-axis.

[0221] 2) Uncertainty data:

[0222]

[0223] u yoz is the concentration value C on the yoz coordinate plane yoz uncertainty.

[0224] Step B3: Based on steps B1 and B2, calculate the detection concentration C in three-dimensional space UVCOD for:

[0225]

[0226] Uncertainty assessment:

[0227]

[0228] Where: u yoz is the concentration value C on the yoz coordinate plane yoz uncertainty.

[0229] Example 3:

[0230] This embodiment is optimized based on embodiment 1 or 2, and uses a UVCOD measuring instrument with a dual-band turbidity compensation method of 550nm (visible light band) and 860nm (near infrared band) to scan and measure the xoz coordinate plane and the yoz coordinate plane, and obtain gridded detection data.

[0231] The UVCOD detection data using dual-band turbidity compensation is:

[0232]

[0233] Among them: A 254 is the absorbance measured by UV254;

[0234] A 550 The absorbance is compensated for turbidity at 550 nm.

[0235] A 890 The absorbance is compensated for turbidity at 890 nm;

[0236] k 550 is the turbidity compensation coefficient of 550nm band;

[0237] k 890 is the turbidity compensation coefficient of 890nm band;

[0238] b is the optical path or solution thickness;

[0239] ε UVCOD It is the equivalent UV254 molar absorptivity, or the calibrated molar absorptivity coefficient.

[0240] in:

[0241] A S =A 254 -k 550 A 550 -k 890 A 890

[0242] The deformation is:

[0243] A 254 =A S +k 550 A 550 +k 890 A 890

[0244] Among them: A S Convert the corresponding absorbance to UVCOD.

[0245] Preferably, the turbidity compensation coefficient k is calculated as follows:

[0246] 1. Prepare standard substance stock solution

[0247] Hexamethylenetetramine (C6H 12 N4) and hydrazine sulfate (N2H6SO4) are used to prepare a highly concentrated standard turbidity solution (hereinafter referred to as turbidity mother solution), and potassium hydrogen phthalate (C8H5KO4) is used to prepare a highly concentrated standard COD solution (hereinafter referred to as COD mother solution).

[0248] 2. Use turbidity mother solution and COD mother solution to prepare: a series of mixed solutions with fixed turbidity and different concentrations; use the device to measure the absorbance of 254nm light source to compensate the absorbance of 550nm and 890nm light sources;

[0249] 254nm light source absorbance:

[0250]

[0251] Turbidity compensation light source absorbance:

[0252]

[0253] Establish the turbidity compensation factor:

[0254]

[0255] The weight value is obtained through matrix operation:

[0256] W=(X T X) -1 X T y;

[0257] Because A S is a constant phase, so the result of the operation k s =0;

[0258] 3. Prepare turbidity solutions of different concentrations to obtain the compensation coefficients for 550nm and 890nm light sources at different concentrations. The absorbance coefficients corresponding to different turbidity solutions are:

[0259]

[0260] Turbidity compensation coefficients corresponding to different turbidity solutions:

[0261]

[0262] 4. Obtain the functional relationship between compensation coefficient and COD solution concentration

[0263] 1) Using piecewise linear relationship:

[0264]

[0265] The absorbance is obtained using polynomial fitting:

[0266] k 550 =a n x n +…+a2x 2 +a1x+c,

[0267] k 890 =b n x n +…+b2x 2 +b1x+d,

[0268] a n and b n are the n-th power fitting coefficients of the 550nm band and the 890nm band respectively;

[0269] c and d are both constant terms of the fitting

[0270] n is the number of fits, determined by the engineer.

[0271] The rest of this embodiment is the same as that of the above-mentioned embodiment 1 or 2, and thus will not be described in detail.

[0272] Example 4:

[0273] This embodiment is optimized based on embodiment 1 or 2. Figure 1 As shown, the UVCOD meter includes a 254nm light source, a multi-band light source array, and a detector module to measure UV254 values ​​and compensated turbidity arrays. The UVCOD meter, which uses a multi-band turbidity compensation method, scans and measures the xoz coordinate plane and the yoz coordinate plane to obtain gridded detection data.

[0274] The UVCOD detection data using multi-band turbidity compensation is:

[0275]

[0276] Among them: A 254 is the absorbance measured by UV254;

[0277] The wavelength is λ i The absorbance corresponding to the turbidity compensation light;

[0278] The wavelength is λi The turbidity compensation coefficient corresponding to the turbidity compensation light;

[0279] b is the optical path or solution thickness;

[0280] ε UVCOD It is the equivalent UV254 molar absorptivity, or the calibrated molar absorptivity coefficient.

[0281] in:

[0282]

[0283] The deformation is:

[0284]

[0285] Among them: A s Convert the corresponding absorbance to UVCOD;

[0286] The wavelength is λ r The absorbance corresponding to the turbidity compensation light;

[0287] The wavelength is λ r The turbidity compensation coefficient corresponding to the turbidity compensation light;

[0288] λ r Compensate light wavelength for monochromatic turbidity;

[0289] r is the type of monochromatic light turbidity compensation light.

[0290] Preferably, the turbidity compensation coefficient is calculated as follows:

[0291] 1. Prepare standard substance stock solution

[0292] Hexamethylenetetramine (C6H 12 N4) and hydrazine sulfate (N2H6SO4) are used to prepare a highly concentrated standard turbidity solution (hereinafter referred to as turbidity mother solution), and potassium hydrogen phthalate (C8H5KO4) is used to prepare a highly concentrated standard COD solution (hereinafter referred to as COD mother solution).

[0293] 2. Use turbidity mother solution and COD mother solution to configure: fixed turbidity, a series of mixed solutions of different concentrations; use the device to measure the absorbance of the 254nm light source and the absorbance of the turbidity compensation light source;

[0294] 254nm light source absorbance:

[0295]

[0296] Turbidity compensation light source absorbance:

[0297]

[0298] Establish the turbidity compensation factor:

[0299]

[0300] The weight value is obtained through matrix operation:

[0301] W=(X T X) -1 X T y;

[0302] 3. Prepare turbidity solutions of different concentrations to obtain the compensation coefficients of the compensation light source at different concentrations. The absorbance coefficients corresponding to different turbidity solutions are:

[0303]

[0304] Turbidity compensation coefficients corresponding to different turbidity solutions:

[0305]

[0306] 4. Obtain the functional relationship between compensation coefficient and COD solution concentration

[0307] 1) Using piecewise linear relationship:

[0308]

[0309] 2) Obtain absorbance using polynomial fitting

[0310] k λ =z n x n +…+z2x 2 +z1x+e

[0311] Where: x is the absorbance measured corresponding to the compensation band light source;

[0312] z n is the n-th power fitting coefficient of the λ band;

[0313] e is the constant term of the fitting.

[0314] The rest of this embodiment is the same as that of the above-mentioned embodiment 1 or 2, and thus will not be described in detail.

[0315] Example 5:

[0316] A high-precision UVCOD measurement system based on three-dimensional coordinate system scanning, such as Figure 1 and Figure 4As shown, the high-precision UVCOD measurement method based on stereo coordinate system scanning is used, including a UVCOD measuring instrument and a data processing unit. The UVCOD measuring instrument includes a 254nm light source, a compensation light source array and a detector module. The detector module is used to obtain the intensity of the transmitted light of the 254nm light source and the compensation light source array;

[0317] The data processing unit includes a UVCOD compensation processing unit, a three-dimensional data acquisition unit, a plane processing unit and a single-dimensional processing unit;

[0318] The compensation UVCOD processing unit is used to obtain UVCOD measurement data using multi-band turbidity compensation;

[0319] The three-dimensional data acquisition unit is used to collect gridded detection data of three-dimensional scanning;

[0320] The plane processing unit is used to calculate the detection concentration C in the three-dimensional space based on the detection data of the xoz coordinate plane and the yoz coordinate plane. UVCOD ;

[0321] The single-dimensional processing unit is used to calculate the detection concentration C in the three-dimensional space based on the single-dimensional detection data of the xoz coordinate plane and the yoz coordinate plane. UVCOD .

[0322] The present invention obtains gridded detection data of adjacent xoz coordinate planes and yoz coordinate planes through plane scanning measurement of the UVCOD measuring instrument, and calculates the detection concentration C in three-dimensional space based on the plane detection data or single-dimensional detection data. UVCOD , effectively improving the accuracy of UVCOD measurements, overcoming the limitations of single-point measurements, and possessing good practicality. Secondly, the present invention employs a multi-band turbidity compensation method for UVCOD measurements, further increasing the accuracy of single-point UVCOD data measurements. Furthermore, the turbidity compensation coefficient obtained through fitting can be dynamically adjusted based on the absorbance of the corresponding compensation wavelength, further accounting for dynamic changes in the monitoring environment and significantly improving the accuracy of compensation.

[0323] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning, characterized in that: The following steps are involved: Step T1: Establish a three-dimensional xyz coordinate system in the three-dimensional space to be measured; Step T2: using a multi-band turbidity compensation UVCOD measuring instrument to scan and measure the xoz coordinate plane and the yoz coordinate plane, and obtaining gridded detection data; Step T3: Based on the detection data of the xoz coordinate plane and the yoz coordinate plane, the detection concentration C in the three-dimensional space is calculated. UVCOD ; The following steps are involved: Step A1: Based on the plane detection data of the xoz coordinate plane, calculate the UVCOD average value of the xoz coordinate plane Step A2: Based on the plane detection data of the yoz coordinate plane, calculate the UVCOD average value of the yoz coordinate plane Step A3: Based on steps A1 and A2, calculate the detection concentration C in three-dimensional space UVCOD for: in: Where: w xoz is the UVCOD weighting coefficient of the xoz coordinate plane; w yoz is the UVCOD weighting coefficient of the yoz coordinate plane; is the UVCOD mean deviation in the xoz coordinate plane; is the UVCOD average deviation in the yoz coordinate plane; Alternatively, step T3: Based on the single-dimensional detection data of the xoz coordinate plane and the yoz coordinate plane, the detection concentration C in the three-dimensional space is calculated. UVCOD ; including the following steps: Step B1: Based on the detection data of the x dimension of the xoz coordinate plane, calculate the concentration value C of the xoz coordinate plane xoz : Where: w xi is the weighting coefficient of the i-th x dimension of the xoz coordinate plane; is the single-dimensional UVCOD scan average value of the xoz coordinate plane; n is the number of subdivision steps on the z axis; Step B2: Based on the detection data of the y dimension of the yoz coordinate plane, calculate the concentration value C of the yoz coordinate plane yoz : Where: w yi is the weighting coefficient of the i-th y dimension of the yoz coordinate plane; is the single-dimensional UVCOD scan average value of the yoz coordinate plane; Step B3: Based on steps B1 and B2, calculate the detection concentration C in three-dimensional space UVCOD for:

2. A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 1, characterized in that, In step A1, the average UVCOD value of the xoz coordinate plane for: In step A2, the UVCOD average value of the yoz coordinate plane for: Where: l is the number of subdivision steps on the x-axis; m is the number of subdivision steps on the y-axis; n is the number of subdivision steps on the z axis; C ij It is the detection data corresponding to the xoz coordinate plane or the yoz coordinate plane.

3. The high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 1, characterized in that: In step A3, the uncertainty u caused by the plane detection data measurement UVCOD for:

4. The high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 1, characterized in that: In step B3, the uncertainty u caused by the measurement of the detection data in the x-dimension and the y-dimension UVCOD for: in: Where: u xoz is the concentration value C on the xoz coordinate plane xoz uncertainty; u yoz is the concentration value C on the yoz coordinate plane yoz uncertainty.

5. A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to any one of claims 1 to 4, characterized in that: In step T2, the detection concentration of the UVCOD measuring instrument using multi-band turbidity compensation is: Among them: A 254 is the absorbance measured by UV254; The wavelength is λ i The absorbance corresponding to the turbidity compensation light; The wavelength is λ i The turbidity compensation coefficient corresponding to the turbidity compensation light; r is the type of monochromatic light turbidity compensation light; b is the optical path or solution thickness; ε UVCOD It is the equivalent UV254 molar absorptivity, or the calibrated molar absorptivity coefficient.

6. The high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 5, characterized in that: The detection concentration of the UVCOD meter using 550nm and 890nm dual-band turbidity compensation is: Among them: A 550 The absorbance is compensated for turbidity at 550 nm. A 890 The absorbance is compensated for turbidity at 890 nm; k 550 is the turbidity compensation coefficient of 550nm band; k 890 It is the turbidity compensation coefficient of 890nm band.

7. The high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 5, characterized in that: Determination of the turbidity compensation coefficient comprises the following steps: Step S1: preparing a standard turbidity solution using hexamethylenetetramine and hydrazine sulfate, and preparing a standard COD solution using potassium hydrogen phthalate; Step S2: using a standard turbidity solution and a standard COD solution, a mixed solution with the same turbidity but different COD is prepared; measuring the absorbance of the 254 nm band and the absorbance of each compensation band; The absorbance measured at 254 nm is: Among them: A (254)n is the absorbance measured at 254 nm of the nth group of mixed solutions; The absorbance measured in each compensation band is: Among them: A Sn is the λ of the nth mixed solution r The UVCOD measured in the compensation band is converted to the corresponding absorbance; is the λ of the nth mixed solution r absorbance measured in the compensation band; Step S3: Establish the turbidity compensation coefficient matrix for each compensation band: Where: k s =0; is λ r Turbidity compensation coefficient of compensation band; Through matrix operations we get: W=(X T X) -1 X T y; Step S4: Change the turbidity and repeat steps S2-S3; wherein the absorbance corresponding to the solutions with different turbidity is: Among them: A sn is the absorbance corresponding to the nth group of turbidity solutions; The turbidity compensation coefficients of each compensation band corresponding to different turbidity solutions are: The piecewise linear relationship between the turbidity compensation coefficient and absorbance of each compensation band is obtained as follows: Step S5: The formula for obtaining the turbidity compensation coefficient and the corresponding absorbance of each compensation band by polynomial fitting is: k λ =z n x n +…+z2x 2 +z1x+e, Where: x is the absorbance measured corresponding to the compensation band light source; z n is the n-th power fitting coefficient of the λ band; e is the constant term of the fitting.

8. The high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 7, characterized in that: When using 550nm and 890nm dual-band turbidity compensation, the turbidity compensation coefficients of the 550nm and 890nm bands are: k 550 =a n x n +…+a2x 2 +a1x+c, k 890 =b n x n +…+b2x 2 +b1x+d, Among them: a n and b n are the n-th power fitting coefficients of the 550nm band and the 890nm band respectively; c and d are both constant terms of the fitting.

9. A high-precision UVCOD measurement system based on three-dimensional coordinate system scanning, based on the high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to any one of claims 1 to 8, characterized in that: It includes a UVCOD measuring instrument and a data processing unit. The UVCOD measuring instrument includes a 254nm light source, a compensation light source array and a detector module. The detector module is used to obtain the intensity of the transmitted light of the 254nm light source and the compensation light source array; The data processing unit includes a UVCOD compensation processing unit, a three-dimensional data acquisition unit, a plane processing unit and a single-dimensional processing unit; The compensation UVCOD processing unit is used to obtain UVCOD measurement data using multi-band turbidity compensation; The three-dimensional data acquisition unit is used to collect gridded detection data of three-dimensional scanning; The plane processing unit is used to calculate the detection concentration C in the three-dimensional space based on the detection data of the xoz coordinate plane and the yoz coordinate plane. UVCOD ; The single-dimensional processing unit is used to calculate the detection concentration C in the three-dimensional space based on the single-dimensional detection data of the xoz coordinate plane and the yoz coordinate plane. UVCOD .

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