High-precision UVCOD (Ultraviolet Chemical Oxygen Demand) measuring method and measuring system based on stereoscopic coordinate system scanning

Abstract

The invention discloses a high-precision UVCOD (Ultraviolet Chemical Oxygen Demand) measuring method and measuring system based on stereoscopic coordinate system scanning, a three-dimensional xyz coordinate system is established in a three-dimensional space to be measured, an xoz coordinate plane and a yoz coordinate plane are scanned and measured respectively by adopting a UVCOD measuring instrument with multiband turbidity compensation, and gridded detection data are obtained; and calculating the detection concentration CUVCOD in the three-dimensional space based on the plane or single-dimensional detection data of the xoz coordinate plane and the yoz coordinate plane. The UVCOD measuring instrument based on multi-band turbidity compensation scans and measures UVCOD of adjacent planes, and the accuracy of single-point UVCOD data measurement is further improved. According to the method, the detection data of the xoz coordinate plane and the yoz coordinate plane can be processed, the detection concentration CUVCOD of the three-dimensional space reflecting the overall measurement condition can be obtained through calculation, the requirement for high precision of UVCOD measurement of the three-dimensional space is met, the limitation of single-point measurement is solved, and good practicability is achieved.

Description

Technical Field

[0001] The 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 detection of COD usually includes potassium dichromate colorimetry, non-dispersive infrared absorption (TOC) and ultraviolet (UV) methods. The existing technology generally uses ultraviolet (UV) method to characterize water quality COD. Specific dissolved organic matter in water samples has strong absorption of ultraviolet light of specific wavelengths. After measuring the absorbance, it can be converted into COD value through correlation. It is more suitable for water bodies without suspended particles, stable composition and colorless and transparent. Ultraviolet-visible absorption spectrum (UVCOD) belongs to electronic absorption spectrum, which is produced by the transition of outer electrons or valence electrons of polyatomic molecules. Usually the electronic energy level interval is 1~20eV, and this energy falls exactly in the ultraviolet-visible light region. Each transition between electronic energy levels is accompanied by changes in the vibrational energy level and rotational energy level of the molecule. Therefore, the absorption line of the electronic transition becomes a wider spectral band containing the fine structure of molecular vibration and rotation. This spectrum can be used for the analysis and research of compounds containing unsaturated bonds, especially compounds containing conjugated systems.

[0003] There are many kinds of organic pollutants in water, mainly including macromolecular organic humus commonly found in natural water bodies (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); aromatic compounds with ultraviolet absorption characteristics (including benzene series, phenols, polycyclic aromatic hydrocarbons (PAHs), which are commonly found in industrial wastewater and domestic sewage); proteins and carbohydrates derived from animal and plant metabolites and human activities, which are easily degraded by microorganisms but will increase the COD value of water bodies at high concentrations; and oil pollutants commonly found in industrial wastewater, including animal and plant oils and petroleum. In the UVCOD monitoring work of the water plant, we pay special attention to those organic substances with ultraviolet absorption characteristics that pose a major 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 COD of water sources, turbidity will reduce the light transmittance of water samples, and suspended particles or suspended matter in the water may adsorb COD reagents, which will affect the results of COD testing. In complex scenarios, especially in high turbidity environments, there are many types of colloids, suspended matter, floccules and other substances that produce turbidity in water, and their composition is complex. 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 required to eliminate the influence, eliminate the interference of turbidity on optical measurement and reagent reaction, and improve the reliability and accuracy of COD 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 conjugated double bonds, benzene rings and other structures) show 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, their stable absorption value 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 (multiple bands can be subdivided and selected according to the actual water body) to achieve interference compensation by comparing the 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, the 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 of water bodies. Due to its 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 disturbance or pollutant diffusion. Taking rivers as an example, when the distribution of water microorganisms at different levels 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 vertical stratification or horizontal gridding continuous monitoring, 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, which adopts a multi-band turbidity compensation method to measure UVCOD, reduces the influence of turbidity on a single detection data, andnow Coordinate plane and summer The detection data of the coordinate plane is used to calculate the detection concentration in three-dimensional space, aiming to overcome the limitations of single-point measurement and significantly improve the detection accuracy of the space to be tested.

[0008] The present invention is mainly achieved through the following technical solutions: A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning includes the following steps: Step T1: Create a three-dimensional space in the three-dimensional space to be tested xyz Coordinate system; Step T2: Scan and measure using a multi-band turbidity compensation UVCOD meter now Coordinate plane and summer Coordinate plane, and obtain gridded detection data; Step T3: Based on now Coordinate plane and summer The plane or one-dimensional detection data of the coordinate plane is used to calculate the detection concentration in three-dimensional space C UVCOD .

[0009] Preferably, the UVCOD measuring instrument performs spatial scanning measurement based on Cartesian coordinates.

[0010] In order to better implement the present invention, further, step T3 includes the following steps: Step A1: Based on now The plane detection data of the coordinate plane is calculated now UVCOD average value on the coordinate plane ; Step A2: Based on summer The plane detection data of the coordinate plane is calculated summer UVCOD average value on the coordinate plane ; Step A3: Based on step A1 and step A2, calculate the detection concentration in three-dimensional space C UVCOD for: , in: , , in: w xoz for now UVCOD weighting coefficients in the coordinate plane; w yoz for summer UVCOD weighting coefficients in the coordinate plane; for now UVCOD mean deviation of the coordinate plane; for summer UVCOD mean deviation of the coordinate plane.

[0011] In order to better implement the present invention, further, in the step A1, now UVCOD average value on the coordinate plane for: , In the step A2, summer UVCOD average value on the coordinate plane for: , in: l for x The number of subdivision steps on the axis; m for y The number of subdivision steps on the axis; n for z The number of subdivision steps on the axis; C ij for now Coordinate plane or summer The detection data corresponding to the coordinate plane.

[0012] In order to better implement the present invention, further, in step A3, the uncertainty caused by the plane detection data measurement is for: .

[0013] In order to better implement the present invention, further, step T3 includes the following steps: Step B1: Based on now Coordinate plane x The detection data of the dimension is calculated now Concentration values ​​on the coordinate plane C xoz : , in: w xi for now The coordinate plane i indivual x The weighting coefficient of the dimension; for nowSingle-dimensional UVCOD scan average of the coordinate plane; n is the number of subdivision steps on the z-axis; Step B2: Based on summer Coordinate plane y The detection data of the dimension is calculated summer Concentration values ​​on the coordinate plane C yoz : , in: w yi for summer The coordinate plane i indivual y The weighting coefficient of the dimension; for summer Single-dimensional UVCOD scan average of the coordinate plane; Step B3: Based on step B1 and step B2, calculate the detection concentration in three-dimensional space C UVCOD for: .

[0014] In order to better implement the present invention, further, in step B3, based on x Dimensions and y Uncertainty caused by measurement of dimensional inspection data for: , in: , , in: for now Concentration values ​​on the coordinate plane C xoz The uncertainty of for summer Concentration values ​​on the coordinate plane C yoz uncertainty.

[0015] 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: , in: is the absorbance measured by UV254; The wavelength is The absorbance corresponding to the turbidity compensation light; The wavelength is The turbidity compensation coefficient corresponding to the turbidity compensation light; r The type of light that compensates for the turbidity of monochromatic light; b is the optical path or solution thickness; It is the equivalent UV254 molar absorption, or the calibrated molar absorption coefficient.

[0016] 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: , in: Absorbance compensated for turbidity in the 550nm band; Absorbance compensated for turbidity at 890 nm; is the turbidity compensation coefficient of 550nm band; It is the turbidity compensation coefficient of 890nm band.

[0017] In order to better implement the present invention, further, the determination of the turbidity compensation coefficient includes the following steps: Step S1: preparing a standard turbidity solution with hexamethylenetetramine and hydrazine sulfate, and preparing a standard COD solution with potassium hydrogen phthalate; Step S2: using the standard turbidity solution and the standard COD solution, preparing a mixed solution with the same turbidity and different COD; measuring the absorbance of the 254nm band and the absorbance of each compensation band; The absorbance measured at 254nm is: , in: 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: , in: A Sn is the nth group of mixed solutions The UVCOD measured in the compensation band is converted to the corresponding absorbance; is the nth group of mixed solutions The absorbance measured in the compensation band; Step S3: Establish the turbidity compensation coefficient matrix of each compensation band: , in: k s =0; for Turbidity compensation coefficient of compensation band; Through matrix operations we get: ; Step S4: Change the turbidity and repeat steps S2-S3; wherein the absorbance corresponding to the solutions with different turbidity is: , in: 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: , in: x To compensate for the absorbance measured by the light source in the wavelength band; z n for Band n Power fitting coefficient; e is the constant term of the fitting.

[0018] In order to better realize 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: , , in: a n and b n They are 550nm and 890nm respectively. n Power fitting coefficient; c and d are all constant terms of the fitting.

[0019] The present invention is mainly achieved through the following technical solutions: A high-precision UVCOD measurement system based on three-dimensional coordinate system scanning is based on the above-mentioned high-precision UVCOD measurement method based on three-dimensional coordinate system scanning, comprising a UVCOD measuring instrument and a data processing unit, wherein the UVCOD measuring instrument comprises a 254nm light source, a compensation light source array and a detector module, wherein 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 based on now Coordinate plane and summer The detection data of the plane of the coordinate plane is used to calculate the detection concentration in three-dimensional space C UVCOD ; The single-dimensional processing unit is used based on now Coordinate plane and summer The single-dimensional detection data of the coordinate plane is used to calculate the detection concentration in three-dimensional space C UVCOD .

[0020] The beneficial effects of the present invention are as follows: The present invention obtains adjacent now Coordinate plane and summer The gridded detection data of the coordinate plane is used to calculate the detection concentration in three-dimensional space based on the plane detection data or the single-dimensional detection data. C UVCOD , which effectively improves the accuracy of UVCOD measurement, solves the limitations of single-point measurement, and has good practicality.

[0021] The present invention adopts a multi-band turbidity compensation method to measure UVCOD, which further increases the accuracy of single-point UVCOD data measurement. Furthermore, the turbidity compensation coefficient obtained based on fitting can be dynamically adjusted according to the absorbance of the corresponding compensation wavelength, further considering the dynamic changes of the monitoring environment, and significantly improving the accuracy of compensation.

[0022] The present invention processes the now Coordinate plane and summerThe UVCOD data on the coordinate plane can quickly calculate the detection concentration in three-dimensional space that reflects the overall measurement situation. C UVCOD On the other hand, the present invention can be processed by a single-dimensional calculation method now Coordinate plane and summer UVCOD data on the coordinate plane can more accurately calculate the detection concentration in three-dimensional space C UVCOD , which meets the high-precision requirements of UVCOD measurement in three-dimensional space and has good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] tú1 The principle block diagram of the UVCOD measuring instrument with multi-band turbidity compensation; tú2 This is a flow chart of the high-precision UVCOD measurement method based on three-dimensional coordinate system scanning in Example 1; tú3 This is a flow chart of the high-precision UVCOD measurement method based on three-dimensional coordinate system scanning in Example 2; tú4 The schematic diagram of the high-precision UVCOD measurement system based on three-dimensional coordinate system scanning of the present invention is shown in FIG. DETAILED DESCRIPTION

[0024] Embodiment 1: A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning is established in the three-dimensional space to be measured. xyz Coordinate system, respectively, using a multi-band turbidity compensation UVCOD measuring instrument to scan and measure now Coordinate plane and summer Coordinate plane, and obtain gridded detection data; based on now Coordinate plane and summer The plane detection data of the coordinate plane is calculated to obtain the detection concentration in three-dimensional space C UVCOD .like tú2 As shown, the specific steps include: Step 1: Data Scanning: Use UVCOD measuring instrument to perform step-by-step plane scanning. The plane scanning process first x The process of axis motion scanning is then y The axis movement scans the process and then moves z axis, and then repeat the plane sweep.

[0025] Obtained through spatial scanning now Coordinate plane scan data: Obtained through spatial scanning summer Coordinate plane scan data: in: l for x The number of subdivision steps on the axis; m for y The number of subdivision steps on the axis; n for z The number of subdivision steps on the axis.

[0026] Step 2: Calculate the detection concentration in three-dimensional space C UVCOD : UVCOD uses plane calculation method to calculate the detection concentration C UVCOD : Calculate all the data on the plane, and calculate the arithmetic mean, standard deviation, average deviation, weighting coefficient and detection concentration in three-dimensional space in turn C UVCOD .

[0027] Step A1: Based on now Plane detection data of coordinate plane, calculation now UVCOD average value on the coordinate plane ; 1) Calculate UVCOD at now Arithmetic mean of coordinate plane scan data: C ij for now Coordinate plane or summer Detection data of the coordinate plane, C ij∈ C nl ; i and j The process data has no practical meaning; l is the subdivision on the x-axis; n for z The number of subdivision steps on the axis.

[0028] 2) Calculate the standard deviation: in: For UVCOD now Standard deviation of the coordinate plane; For UVCOD now The arithmetic mean of the coordinate plane scan data; C ij For process operation data, C ij∈ C nl ; work The process data has no practical meaning; l is the number of subdivision steps on the x-axis; n is the number of subdivision steps on the z-axis; 3) Calculate the average deviation: in: For UVCOD now Standard deviation of the coordinate plane; For UVCOD now Mean deviation of the coordinate plane; l is the number of subdivision steps on the x-axis; n is the number of subdivision steps on the z-axis.

[0029] Step A2: Based on summer Plane detection data of coordinate plane, calculation summer UVCOD average value on the coordinate plane ; 1) Calculate UVCOD at y The arithmetic mean of the scan data in the oz coordinate plane: in: C ij For process operation data, C ij∈ C mn ; work Process data has no practical meaning; m is the number of subdivision steps on the y-axis; n is the number of subdivision steps on the z-axis.

[0030] 2) Calculate the standard deviation: 3) Calculate the average deviation: Calculation method of weighting coefficient: w xoz For turbidity now Weighting coefficients of the coordinate plane; w yoz For turbidity summer Weighting coefficients for the coordinate plane.

[0031] Step A3: Based on step A1 and step A2, calculate the detection concentration in three-dimensional space C UVCOD : Step 3: Weighted average uncertainty assessment: Uncertainty caused by measurement (Class A).

[0032] Embodiment 2: A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning is established in the three-dimensional space to be measured. xyz Coordinate system, respectively, using a multi-band turbidity compensation UVCOD measuring instrument to scan and measure now Coordinate plane and summer Coordinate plane, and obtain gridded detection data; based on now Coordinate plane and summer The single-dimensional detection data of the coordinate plane is calculated to obtain the detection concentration in three-dimensional space C UVCOD .like tú3 As shown, the specific steps include: Step 1: Data scanning is the same as that described in Example 1, so it will not be repeated here.

[0033] Step 2: Calculate the detection concentration using a single-dimensional calculation method C UVCOD , use the detection data of the x-axis and y-axis for 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 calculations on different single-dimensional data to obtain the detection concentration in three-dimensional space C UVCOD .

[0034] The single-dimensional calculation model is: 1. Calculate the arithmetic mean in: gis the number of subdivision steps in a single dimension, g ∈{ l m}; It is the arithmetic mean obtained from a single scan in a single dimension; C i Calculates data for the subdivision measurement process of single-dimensional scanning. C i ∈ C nl ∪ C nm ; i The process data has no practical meaning.

[0035] 2. Calculate the standard deviation in: is the standard deviation of turbidity in a single dimension.

[0036] 3. Calculate the average deviation in: is the average deviation of turbidity in a single dimension.

[0037] 4. Single Dimension Weighting Coefficient Preferably, the specific steps of the one-dimensional calculation method are as follows: Step B1: Based on now Coordinate plane x The detection data of the dimension is calculated now Concentration values ​​on the coordinate plane C xoz : (1) The unit dimension calculation model is used to obtain now Coordinate plane x The dimension data is: Calculate the arithmetic mean as: The standard deviation is: The weighting coefficient is: (2) The unit dimension calculation model is used to obtain summer Coordinate plane y The dimension data is: The arithmetic mean is: The standard deviation is: Weighting coefficient: (3) Calculation now Concentration values ​​on the coordinate plane C xoz : 1) UVCOD data: in: w xi for now The coordinate plane i indivual x The weighting coefficient of the dimension; C xoz for now Concentration values ​​on the coordinate plane; n is the number of subdivision steps on the z-axis.

[0038] for now Single-dimensional UVCOD scan average of the coordinate plane; 2) Uncertainty data: in: for now Concentration values ​​on the coordinate plane C xoz The uncertainty of against summer The coordinate plane is processed as follows: Step B2: Based on summer Coordinate plane y The detection data of the dimension is calculated summer Concentration values ​​on the coordinate plane C yoz : 1) UVCOD data: in: C yoz for summer Concentration values ​​on the coordinate plane; w yi for summer The coordinate plane i indivual y The weighting coefficient of the dimension; : summer Single-dimensional UVCOD scan average of the coordinate plane; n is the number of subdivision steps on the z-axis.

[0039] 2) Uncertainty data: for summer Concentration values ​​on the coordinate plane C yoz uncertainty.

[0040] Step B3: Based on step B1 and step B2, calculate the detection concentration in three-dimensional space C UVCOD for: Uncertainty Assessment: in: for summer Concentration values ​​on the coordinate plane C yoz uncertainty.

[0041] Embodiment 3: This embodiment is optimized on the basis of embodiment 1 or 2, and adopts the UVCOD measuring instrument scanning measurement of the dual-band turbidity compensation method of 550nm (visible light band) and 860nm (near infrared band) now Coordinate plane and summer Coordinate plane and obtain gridded detection data.

[0042] The UVCOD detection data using dual-band turbidity compensation is: in: is the absorbance measured by UV254; Absorbance compensated for turbidity in the 550nm band; Absorbance compensated for turbidity at 890 nm; is the turbidity compensation coefficient of 550nm band; is the turbidity compensation coefficient of 890nm band; b is the optical path or solution thickness; It is the equivalent UV254 molar absorption, or the calibrated molar absorption coefficient.

[0043] in: Deformation gives: in: The absorbance corresponding to UVCOD conversion.

[0044] Preferably, the turbidity compensation coefficient k The calculation method is as follows: 1. Prepare the stock solution of standard substances 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).

[0045] 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 254nm light source to compensate the absorbance of 550nm and 890nm light sources; 254nm light source absorbance: Turbidity compensation light source absorbance: Establish the turbidity compensation factor: The weight value is obtained through matrix operation: because is a constant phase, so the result of the operation is ; 3. Prepare turbidity solutions of different concentrations to obtain compensation coefficients for 550nm and 890nm light sources at different concentrations.

[0046] Absorbance coefficients corresponding to different turbidity solutions: Turbidity compensation coefficients corresponding to different turbidity solutions: 4. Obtain the functional relationship between compensation coefficient and concentration COD solution 1) Using piecewise linear relationship: The absorbance is obtained by polynomial fitting: , , a n and b n They are 550nm and 890nm respectively. n Power fitting coefficient; c and d All are constant terms of the fitting n The number of fits is determined by the engineer.

[0047] The other parts of this embodiment are the same as those of the above-mentioned embodiment 1 or 2, and thus will not be described in detail.

[0048] Embodiment 4: This embodiment is optimized based on embodiment 1 or 2. tú1 As shown, the UVCOD measuring instrument includes a 254nm light source, a multi-band light source array and a detector module, and measures the UV254 measurement value and the compensated turbidity array. Scanning measurement of the UVCOD measuring instrument using the multi-band turbidity compensation method now Coordinate plane and summer Coordinate plane and obtain gridded detection data.

[0049] The UVCOD detection data using multi-band turbidity compensation is: in: is the absorbance measured by UV254; The wavelength is The absorbance corresponding to the turbidity compensation light; The wavelength is The turbidity compensation coefficient corresponding to the turbidity compensation light; b is the optical path or solution thickness; It is the equivalent UV254 molar absorption, or the calibrated molar absorption coefficient.

[0050] in: Deformation gives: in: Convert the corresponding absorbance to UVCOD; The wavelength is The absorbance corresponding to the turbidity compensation light; The wavelength is The turbidity compensation coefficient corresponding to the turbidity compensation light; Compensate light wavelength for monochromatic turbidity; r It is the type of light that compensates the turbidity of monochromatic light.

[0051] Preferably, the turbidity compensation coefficient is calculated as follows: 1. Prepare the stock solution of standard substances 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).

[0052] 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; 254nm light source absorbance: Turbidity compensation light source absorbance: Establish the turbidity compensation factor: The weight value is obtained through matrix operation: 3. Prepare turbidity solutions of different concentrations to obtain the compensation coefficients of the compensation light sources at different concentrations.

[0053] Absorbance coefficients corresponding to different turbidity solutions: Turbidity compensation coefficients corresponding to different turbidity solutions: 4. Obtain the functional relationship between compensation coefficient and concentration COD solution 1) Using piecewise linear relationship: 2) Obtain absorbance using polynomial fitting in: x To compensate for the absorbance measured by the light source in the wavelength band; z n for Bandn Power fitting coefficient; e is the constant term of the fitting.

[0054] The other parts of this embodiment are the same as those of the above-mentioned embodiment 1 or 2, and thus will not be described in detail.

[0055] Embodiment 5: A high-precision UVCOD measurement system based on stereo coordinate system scanning, such as tú1 and tú4 As 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, and 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 based on now Coordinate plane and summer The detection data of the plane of the coordinate plane is used to calculate the detection concentration in three-dimensional space C UVCOD ; The single-dimensional processing unit is used based on now Coordinate plane and summer The single-dimensional detection data of the coordinate plane is used to calculate the detection concentration in three-dimensional space C UVCOD .

[0056] The present invention obtains adjacent now Coordinate plane and summer The gridded detection data of the coordinate plane is used to calculate the detection concentration in three-dimensional space based on the plane detection data or the single-dimensional detection data. C UVCOD , effectively improving the accuracy of UVCOD measurement, solving the limitation of single-point measurement, and having good practicality. Secondly, the present invention adopts a multi-band turbidity compensation method to measure UVCOD, further increasing the accuracy of single-point UVCOD data measurement. Furthermore, the turbidity compensation coefficient obtained based on fitting can be dynamically adjusted with the absorbance of the corresponding compensation wavelength, further considering the dynamic changes of the monitoring environment, and significantly improving the accuracy of compensation.

[0057] 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 protection scope 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: Create a three-dimensional space in the three-dimensional space to be tested xyz Coordinate system; Step T2: Scan and measure using a multi-band turbidity compensation UVCOD meter xoz Coordinate plane and yoz Coordinate plane, and obtain gridded detection data; Step T3: Based on xoz Coordinate plane and yoz The plane or one-dimensional detection data of the coordinate plane is used to calculate the detection concentration in three-dimensional space C UVCOD .

2. A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 1, characterized in that: The step T3 comprises the following steps: Step A1: Based on xoz The plane detection data of the coordinate plane is calculated xoz UVCOD average value on the coordinate plane ; Step A2: Based on yoz The plane detection data of the coordinate plane is calculated yoz UVCOD average value on the coordinate plane ; Step A3: Based on step A1 and step A2, calculate the detection concentration in three-dimensional space C UVCOD for: ， in: , ， in: w xoz for xoz UVCOD weighting coefficients in the coordinate plane; w yoz for yoz UVCOD weighting coefficients in the coordinate plane; for xoz UVCOD mean deviation of the coordinate plane; for yoz UVCOD mean deviation of the coordinate plane.

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

4. A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 2, characterized in that: In step A3, the uncertainty caused by the plane detection data measurement for: 。 5. The high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 1 is characterized in that: The step T3 comprises the following steps: Step B1: Based on xoz Coordinate plane x The detection data of the dimension is calculated xoz Concentration values ​​on the coordinate plane C xoz : ， in: w xi for xoz The coordinate plane i indivual x The weighting coefficient of the dimension; for xoz Single-dimensional UVCOD scan average of the coordinate plane; n is the number of subdivision steps on the z-axis; Step B2: Based on yoz Coordinate plane y The detection data of the dimension is calculated yoz Concentration values ​​on the coordinate plane C yoz : ， in: w yi for yoz The coordinate plane i indivual y The weighting coefficient of the dimension; for yoz Single-dimensional UVCOD scan average of the coordinate plane; Step B3: Based on step B1 and step B2, calculate the detection concentration in three-dimensional space C UVCOD for: 。 6. A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 5, characterized in that: In step B3, based on x Dimensions and y Uncertainty caused by measurement of dimensional inspection data for: ， in: , ， in: for xoz Concentration values ​​on the coordinate plane C xoz The uncertainty of for yoz Concentration values ​​on the coordinate plane C yoz uncertainty.

7. A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to any one of claims 1 to 6, characterized in that: In step T2, the detection concentration of the UVCOD measuring instrument using multi-band turbidity compensation is: ， in: is the absorbance measured by UV254; The wavelength is The absorbance corresponding to the turbidity compensation light; The wavelength is The turbidity compensation coefficient corresponding to the turbidity compensation light; r The type of light that compensates for the turbidity of monochromatic light; b is the optical path or solution thickness; It is the equivalent UV254 molar absorption, or the calibrated molar absorption coefficient.

8. A high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 7, characterized in that: The detection concentration of the UVCOD measuring instrument using 550nm and 890nm dual-band turbidity compensation is: ， in: Absorbance compensated for turbidity in the 550nm band; Absorbance compensated for turbidity at 890 nm; is the turbidity compensation coefficient of 550nm band; It is the turbidity compensation coefficient of 890nm band.

9. The high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 7, characterized in that: The determination of the turbidity compensation coefficient comprises the following steps: Step S1: preparing a standard turbidity solution with hexamethylenetetramine and hydrazine sulfate, and preparing a standard COD solution with potassium hydrogen phthalate; Step S2: using the standard turbidity solution and the standard COD solution, preparing a mixed solution with the same turbidity and different COD; measuring the absorbance of the 254nm band and the absorbance of each compensation band; The absorbance measured at 254nm is: ， in: 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: ， in: A Sn is the nth group of mixed solutions The UVCOD measured in the compensation band is converted to the corresponding absorbance; is the nth group of mixed solutions The absorbance measured in the compensation band; Step S3: Establish the turbidity compensation coefficient matrix of each compensation band: ， in: k s =0; for Turbidity compensation coefficient of compensation band; Through matrix operations we get: ； Step S4: Change the turbidity and repeat steps S2-S3; wherein the absorbance corresponding to the solutions with different turbidity is: ， in: 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: ， in: x To compensate for the absorbance measured by the light source in the wavelength band; z n for Band n Power fitting coefficient; e is the constant term of the fitting.

10. The high-precision UVCOD measurement method based on three-dimensional coordinate system scanning according to claim 9, characterized in that: When using 550nm and 890nm dual-band turbidity compensation, the turbidity compensation coefficients of the 550nm and 890nm bands are: ， ， in: a n and b n They are 550nm and 890nm respectively. n Power fitting coefficient; c and d are all constant terms of the fitting.

11. 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 10, 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 based on xoz Coordinate plane and yoz The detection data of the plane of the coordinate plane is used to calculate the detection concentration in three-dimensional space C UVCOD ; The single-dimensional processing unit is used based on xoz Coordinate plane and yoz The single-dimensional detection data of the coordinate plane is used to calculate the detection concentration in three-dimensional space C UVCOD .

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