| Water is the source of life and the basic guarantee of industrial production and social life.How to ensure the safety of water environment and prevent water pollution is a hot topic in today’s society.Water quality detection undertakes the basic work in the prevention and control of water pollution and is an important means to ensure the safety of water environment.It is undoubtedly of great significance to carry out the research on the principle,technology and equipment of water quality detection.At present,the traditional water quality detection methods based on chemical method have some defects,such as complex operation,secondary pollution and long detection period.In recent years,UV-vis spectroscopy has been rapidly popularized in the field of water quality detection,and it has the advantages of rapid detection,no secondary pollution,real-time in-situ and so on.However,how to use industrial light source and spectrometer to build a feasible water quality detection system,how to remove spectral noise,and how to quickly and accurately predict water quality parameters are still problems in UV-vis water quality detection.Based on this,this paper is supported by the National Natural Science Foundation of China(61805029),Chongqing Science and Technology Commission technological Innovation and Application Development Project(cstc2021jscxgksb X0056)and Chongqing Natural Science Foundation(cstc2020jcyj-msxm X0553).The key technologies of water quality detector based on UV-vis spectroscopy are studied in this paper.the main work is as follows:(1)The research status of UV-vis spectrum water quality detector at home and abroad is analyzed,the overall design scheme of the water quality detector is determined,and the core components are selected.A set of water quality detection system based on UV-vis spectrum is designed,the modules of spectrum signal acquisition,transmission,processing and analysis are built,and a set of water quality detection and analysis software based on Py Qt5 is developed to realize the control of water quality detection system and the processing and analysis of spectrum data.(2)A spectral signal denoising algorithm based on fully adaptive noise set empirical mode decomposition(CEEMDAN)and dual-tree complex wavelet transform(DT-CWT)is proposed.The algorithm uses CEEMDAN to decompose the signal into intrinsic mode function(IMF),and makes linear correlation analysis through normalized autocorrelation function and cross-correlation number to determine the boundary between high-frequency noise components and low-frequency signal components.Then the noisy high-frequency IMF component is processed by DT-CWT threshold denoising algorithm,and the signal-to-noise ratio of spectral signal is effectively improved by reconstructing the IMF high-frequency component after DTCWT processing and the low-frequency component of IMF demarcated by CEEMDAN.(3)Aiming at the calculation of chemical oxygen demand(COD)parameters,the experiments of several groups of standard solutions with different concentrations(potassium hydrogen phthalate solution)and measured water samples were carried out,and the prediction of water quality COD based on UV-vis absorption spectroscopy was studied.Through the particle swarm optimization algorithm to reduce the dimension of the original spectral data,select the characteristic wavelength information,combined with the linear regression algorithm to predict the water sample COD,and obtain the calculated water quality COD value.The experimental results show that the designed water quality detection system can realize the rapid detection of specific water samples and the effective solution of COD and other parameters. |
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