EP-4343307-B1 - WATER QUALITY TESTING METHOD AND WATER QUALITY TESTING APPARATUS

EP4343307B1EP 4343307 B1EP4343307 B1EP 4343307B1EP-4343307-B1

Inventors

FENG, JUNJIE
SUN, BING
JIANG, Huiyun
JIN, YAN
XIAO, Anshan
WANG, Haozhi
WANG, Shiqiang

Dates

Publication Date: 20260513
Application Date: 20220525

Claims (12)

A water quality testing method, comprising: obtaining a test sample, the test sample comprising a target test substance; determining a reference substance corresponding to the test sample; determining a third chromaticity of the reference substance under a first environment, and a fourth chromaticity of the reference substance under a second environment; obtaining a chromaticity-concentration mapping relationship characterizing a mapping relationship between the chromaticity of the test sample under the second environment and the concentration of the target test substance; determining an absolute value of the chromaticity difference between the fourth chromaticity and the third chromaticity, and o if an absolute value of the chromaticity difference between the fourth chromaticity and the third chromaticity is greater than a pre-set deviation threshold: constructing a chromaticity correction model by a neural network algorithm or a multivariate non-linear fitting method according to a chromaticity difference between the fourth chromaticity and the third chomaticity; acquiring a first chromaticity of the test sample under the first environment; determining a second chromaticity of the test sample under the second environment based on the first chromaticity and the chromaticity correction model; and determining a concentration of the target test substance based on the determined second chromaticity and the chromaticity-concentration mapping relationship; and o in a case where the absolute value of the chromaticity difference between the fourth chromaticity and the third chromaticity is less than or equal to the pre-set deviation threshold, the method further comprises: acquiring the chromaticity of the test sample under the first and obtaining the concentration of the target test substance in the test sample based on the chromaticity-concentration mapping relationship and the chromaticity of the test sample under the first environment, wherein the first environment is a test site environment in which the test sample is located; and the second environment is a laboratory standard environment.
The water quality testing method according to claim 1, characterized in that obtaining the test sample comprises: judging whether an aqueous solution of the target test substance is colored or not, and judging whether the aqueous solution of the target test substance has an interference color or not; taking the aqueous solution of the target test substance as a test sample if the aqueous solution of the target test substance is colored and has no interference color; selecting a corresponding test reagent according to the target test substance if the aqueous solution of the target test substance is colorless or has an interference color, and fusing the selected test reagent with the aqueous solution of the target test substance to obtain a test sample, preferably, wherein the test reagent corresponding to the target test substance is a test reagent that undergoes a chromogenic reaction upon fusion with an aqueous solution of the target test substance.
The water quality testing method according to claim 1, characterized in that determining the third chromaticity of the reference substance under the first environment, and the fourth chromaticity of the reference substance under the second environment comprises: acquiring color image information of the reference substance under the second environment, and performing color image information processing according to a preset image algorithm; performing chromaticity extraction on the processed color image information of the reference substance under the second environment to obtain a fourth chromaticity of the reference substance under the second environment; acquiring color image information of the reference substance under a first environment, and performing color image information processing according to a preset image algorithm; performing chromaticity extraction on the processed color image information of the reference substance under the first environment to obtain a third chromaticity of the reference substance under the first environment, preferably, wherein the preset image algorithm comprises at least: image transformation, key region selection, edge testing, noise reduction, smoothing and chromaticity enhancement, more preferably, wherein the color image information chromaticity extraction under the second environment and the color image information chromaticity extraction under the first environment are performed under a same chromaticity system, and the chromaticity system is any one of: RGB, HSV, CMYK, CIE, and LAB.
The water quality testing method according to claim 1, characterized in that when the chromaticity correction model construction is performed, the chromaticity correction model construction is performed using a neural network algorithm and a multivariate non-linear fitting method respectively, and the two constructed chromaticity correction models are trained respectively based on a certain selected reference substance, and training results of the two chromaticity correction models are obtained; the training results of the two chromaticity correction models are compared: when an absolute value of a difference between the two is less than a preset threshold, one chromaticity correction model is optionally selected as a final chromaticity correction model; when an absolute value of a difference between the two is greater than or equal to a preset threshold value, the two are compared with a standard chromaticity of the selected reference substance, respectively, and a chromaticity correction model corresponding to a training result having a smaller absolute value of a difference with the standard chromaticity of the selected reference substance is selected as a final chromaticity correction model.
The water quality testing method according to claim 3, characterized in that before performing color image information processing on the color image information of the reference substance according to the preset image algorithm, the method further comprises: determining that the color image information of the reference substance meets a testing requirement, and determining that the color image information of the test sample meets the testing requirement, preferably, wherein the testing requirement comprises at least: image pixels, illumination intensity and light uniformity of a color image.
The water quality testing method according to claim 1, characterized in that obtaining a chromaticity-concentration mapping relationship comprises: constructing the chromaticity-concentration mapping relationship comprising: selecting a plurality of aqueous solutions containing the target test substance, wherein the concentration of the target test substance in each aqueous solution is known and different; acquiring chromaticities of the plurality of aqueous solutions comprising the target test substance under the second environment; obtaining a function relationship between the concentration of the target test substance and the chromaticity of the aqueous solution of the target test substance under the second environment based on the concentration of the target test substance in each aqueous solution and the corresponding chromaticity of each aqueous solution under the second environment, and obtaining the chromaticity-concentration mapping relationship from the function relationship.
The method according to claim 1, characterized in that the reference substance is a standard color card; a plurality of color regions exist on the standard color card, when performing reference substance color degree extraction, chromaticities of all the color regions on the standard color card are simultaneously extracted to obtain a first chromaticity set; the first chromaticity set is subjected to chromaticity correction model construction as a training sample, or the reference substance is a paper microfluidic chip, a color card, a microchannel chip or a color developing apparatus; the reference substance is colored by any one of the following modes: an intrinsic color of the reference substance, dye addition, addition of a color reaction system.
A water quality testing device for use with a reference substance, comprising: a mixing module configured to obtain a test sample, the test sample comprising a target test substance; an acquisition module configured to determine a reference substance corresponding to the test sample, and acquire a first chromaticity of the test sample under the first environment, a third chromaticity of the reference substance under a first environment, and a fourth chromaticity of the reference substance under a second environment; a correction model construction module configured to: determine an absolute value of the chromaticity difference between the fourth chromaticity and the third chromaticity, compare the determined absolute value of the chromaticity difference to a pre-set deviation threshold, and if the absolute value of the chromaticity difference is greater than a preset deviation threshold, construct a chromaticity correction model by a neural network algorithm or a multivariate non-linear fitting method according to a chromaticity difference between the fourth chromaticity and the third chromaticity, a revision module configured to determine the second chromaticity of the test sample under a second environment based on the first chromaticity and the chromaticity correction model constructed by the correction model construction module; and a target test substance concentration determining module configured to determine a concentration of the target test substance based on a pre-set chromaticity-concentration mapping relationship and on the second chromaticity determined by the revision module, wherein in a case where the absolute value of the chromaticity difference between the fourth chromaticity and the third chromaticity is determined to be less than or equal to the pre-set deviation threshold, the target test substance concentration determining module further configured to obtain the concentration of the target test substance in the test sample based on the pre-set chromaticity-concentration mapping relationship and the chromaticity of the test sample under the first environment, wherein the pre-set chromaticity-concentration mapping relationship reflects a mapping relationship between the chromaticity of the test sample under the second environment and the concentration of the target test substance, and wherein the first environment is a test site environment in which the test sample is located; and the second environment is a laboratory standard environment.
The water quality testing device according to claim 8, wherein the mixing module is configured to judge whether an aqueous solution of the target test substance is colored or not, and whether the aqueous solution of the target test substance has an interference color or not, such that, in use, the aqueous solution of the target test substance is taken as a test sample if the aqueous solution of the target test substance is colored and has no interference color; or a corresponding test reagent according to the target test substance is selected if the aqueous solution of the target test substance is colorless or has an interference color, and the selected test reagent is fused with the aqueous solution of the target test substance to obtain a test sample.
The water quality testing device according to claim 8, wherein to acquire the third chromaticity of the reference substance under the first environment and the fourth chromaticity of the reference substance under the second environment, the acquisition module is configured to acquire color image information of the reference substance under the second environment, and to perform color image information processing according to a preset image algorithm; to perform chromaticity extraction on the processed color image information of the reference substance under the second environment to obtain the fourth chromaticity of the reference substance under the second environment; to acquire color image information of the reference substance under the first environment, and to perform color image information processing according to a preset image algorithm; to perform chromaticity extraction on the processed color image information of the reference substance under the first environment to obtain the third chromaticity of the reference substance under the first environment, preferably, the preset image algorithm comprises at least: image transformation, key region selection, edge testing, noise reduction, smoothing, and chromaticity enhancement.
The water quality testing device according to claim 10, characterized in that , the acquisition module is further configured to determine whether the color image information of the reference substance meets a testing requirement, and determine whether the color image information of the test sample meets the testing requirement; in a case where the color image information of the reference substance is determined to meet the testing requirement, and the color image information of the test sample is determined to meet the testing requirement, color image information processing is performed on the color image information of the reference substance and on the color image information of the test sample according to a preset image algorithm, preferably, the acquisition module comprises: an image acquisition module, configured to acquire color image information of the reference substance under a second environment; and acquire color image information of the reference substance and color image information of the target test substance under a first environment; an image processing module, configured to perform color image information processing on the color image information of the reference substance and the color image information of the target test substance according to a preset image algorithm, and perform chromaticity extraction on the processed color image information, more preferably, the image acquisition module comprises a camera, a cell phone, a camera, a scanner or a monitoring apparatus.
A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon instructions that, when run on the device of any one of claims 8-11, cause the device to perform the water quality testing method according to any one of claims 1-7.

Description

Field of the Invention The present disclosure relates to the technical field of environmental monitoring, in particular, to a water quality testing method and a water quality testing device. Background of the Invention The quantitative measurement of a target substance in a body of water is widely used in processes such as industrial water quality testing, environmental testing, biochemical analysis, accident investigation, domestic water testing, sewage treatment, and relates to the fields of industrial production, medical health, and daily life. Water quality testing techniques mainly include chemical analysis methods and instrumental analysis methods and the like, such as gravimetric analysis, titration analysis, optical analysis, electrochemical analysis, chromatography, mass spectrometry and the like. Many of the conventional testing methods have a large apparatus volume, a slow analysis speed, low work efficiency and a large amount of reagents, which are difficult to adapt to the on-site and field working environment conditions and difficult for portable use. While the development of large and sophisticated monitoring systems continues, there is a growing interest in the development of small, portable, self-continuous, simple and rapid monitoring techniques. To address the problems of inefficient testing and harsh monitoring conditions of existing water body target substance quantitative determination methods, there is a need to create a water quality testing method based on digital image processing according to a small portable testing apparatus. Carvalho, Pedro H., et al. "Estimation of sulfonamides concentration in water based on digital colourimetry" in: Iberian Conference on Pattern Recognition and Image Analysis. Cham: Springer International Publishing, 2019. S. 355-366, describes a method of determining the concentration of sulfonamides concentration in water. In the proposed method, photographs of samples next to a colour reference target are acquired to build a dataset. An algorithm is used to detect the reference target, based on binarisation algorithms, in order to standardise the collected images using a colour correction matrix converting from RGB to XYZ, providing a necessary colour constancy between photographs from different devices. Afterwards, the sample is extracted through edge detection and Hough transform algorithms. Finally, the sulfonamide concentration is estimated resorting to an experimentally designed calibration curve, which correlates the concentration and colour information. Lopez-Ruiz Nuria, et al. "Smartphone-based simultaneous pH and nitrite colorimetric determination for paper microfluidic devices" in Analytical chemistry, 2014, 86. Jg., Nr. 19, S. 9554-9562, describes an Android application for measurement of nitrite concentration and pH determination in combination with a low-cost paper-based microfluidic device. The application uses seven sensing areas, containing the corresponding immobilized reagents, to produce selective color changes when a sample solution is placed in the sampling area, and a reference area used to normalise the color coordinates of the sensing areas. Under controlled conditions of light, using the flash of the smartphone as a light source, the image captured with the built-in camera is processed using a customized algorithm for multidetection of the colored sensing areas. Summary of the Invention The present disclosure provides a water quality testing method and a water quality testing device aiming at the technical problems in the prior art that a complex testing apparatus is required, the testing application range is narrow and the testing environment is high. The method is simple, the testing speed is fast, the application range is wide, the method does not depend on specific photographing conditions, the method has good applicability to different photographing apparatuses, light sources and photographing methods, and the testing accuracy is high. In order to achieve the above object, the present invention provides a water quality testing method according to claim 1, the method comprising: obtaining a test sample, the test sample comprising a target test substance; determining a reference substance corresponding to the test sample;determining a third chromaticity of the reference substance under a first environment, and a fourth chromaticity of the reference substance under a second environment;obtaining a chromaticity-concentration mapping relationship characterizing a mapping relationship between the chromaticity of the test sample under the second environment and the concentration of the target test substance;determining an absolute value of the chromaticity difference between the fourth chromaticity and the third chromaticity, and if an absolute value of the chromaticity difference between the fourth chromaticity and the third chromaticity is greater than a preset deviation threshold: constructing a chromaticity correction model by a