Research In Water Quality COD Detection Technology Based On UV-Vis Spectrum Analysis

Water is the source of life and is an indispensable material foundation for all life.The ancients believed that water is the gift of Heaven to mankind and it's inexhaustible.However,we know that it is not the case.The total amount of global water resources is about 1.386 billion cubic kilometers,but freshwater resources only account for 2.5% of the total and 69.5% of the global freshwater resources are in the form of glaciers and cannot be used by humans.In addition,the imbalance in the distribution of fresh water resources and the waste of water resources have led to that more than 60% of the world's regions lack water.China is also facing a great water crisis.The number of people in our country has gradually increased,and the supply of water has also increased.In addition,the indiscriminate discharge of wastewater has led to frequent water cuts in many areas.With the development of industrialization,water pollution has occurred frequently,and directly affecting human survival and development.Water quality detection is one of the necessary tasks to protect water resources.In the field of water quality detection,ultraviolet-visible spectrum analysis is an important research method.It is a purely physical method that does not require chemical reagents.This method can analyze different types of water and detect a variety of water quality parameters,which has been developing rapidly in recent years.In the water quality detection,a very important water quality parameter is the chemical oxygen demand.Detecting the content of COD and evaluating the detection results can help to understand the pollution status of the water quality and facilitate the treatment.This paper is based on water samples collected from the Dianchi Lake.The spectral data was collected by self-made ZW-11 W ultraviolet-visible spectrometer.The absorbance of the solution was measured according to the principle of ultraviolet-visible absorption spectroscopy.In addition,a mobile APP based on water quality monitoring of Android system is designed for water quality monitoring.It contains 7 modules of real-time map,water quality query,water quality analysis,water quality,water quality warning,environmental report and system management,which is conducive to monitoring water environment.The spectral data is processed by different method,which include principal component regression,partial least squares regression,and ridge regression.The processing results were compared.Fitting predictions show that the prediction results of principal component regression and partial least squares regression are more accurate than those of the ridge regression.And in the prediction of the results within the detection limit,the partial least squares regression prediction results are better than the principal component regression results.However,in the prediction of the results outside the detection limit,the principal component regression prediction results are better than the partial least squares regression results.This paper is only a preliminary experimental result based on Dianchi water,and it is necessary to further improve the adaptability and accuracy of the detection.