Water Quality Detection Method And Portable Instrument Development Based On Multispectral Sensor

The world is facing water crisis,water pollution problems are becoming more and more serious,the traditional instruments for testing water quality are bulky and complex in structure.In order to simplify the instrument design and improve the measurement accuracy,multi-spectral portable water quality detection instruments are developed.Therefore,this paper proposes a method of applying multi-wavelength sensors to detect pollutants in water,and designs a portable water quality testing instrument based on visible multi-wavelength spectral sensors.The instrument selects the best absorption measurement wavelength according to the degree of light absorption of the solution,then processes the experimental results and establishes the detection model,and compares the experimental results with the spectrophotometer measurement results,analyzes the accuracy of the method,and conducts independent sample t-test for both methods,proves that the method is not significantly different from the standard detection method,and can be applied to the detection of other substances content in water.The main research contents and conclusions are as follows:（1）Based on the research and analysis of the current status of water quality detection,in order to simplify the structure of water quality detection instruments and improve the effectiveness of water quality measurement methods,combined with the research status of water quality detection methods and portable instruments,a water quality detection method based on multispectral sensors is proposed.（2）A water quality detection device based on multi spectral sensor is designed.The device uses LED with color temperature of 5700 k as the light source,collects the light intensity data of each channel of the solution through the multi spectral sensor,calculates the absorbance value by combining the upper computer software designed and developed based on Visual Studio platform,and uses the least square method to fit the experimental data to obtain the corresponding standard curve of each substance.（3）The designed device is used to measure the contents of ammonia nitrogen,sulfide,dissolved oxygen,nitrite nitrogen and iron in water.The optimal wavelength corresponding to each substance is obtained according to the solution absorbance and the detection model is established.Comparing the measurement results with the spectrophotometer measurement results,the measurement results of the experimental device in this paper have less error than those measured by the spectrophotometer,which indicates that the accuracy is high.Through independent sample t-test（p>0.05）,it is proved that there is no significant difference between the measurement results and the traditional visible spectrophotometer,which verifies the feasibility of multi spectral sensor for substance measurement.（4）Complete the design of portable water quality testing instrument.The instrument is based on multi spectral sensor and LED light source,and adopts raspberry Pico for data processing.The intelligent serial port screen displays the standard curve and measurement results to realize the rapid detection of water quality.The reliability and precision of the instrument are verified through the measurement of actual water samples.The software for downloading water quality multi parameter measurement project based on Windows platform developed by the instrument can realize the selection of a variety of measuring substances.