| Water is an integral part of human life,and drinking clean and safe water is essential to maintaining good health.The multi-parameter water quality test of urban pipe network water and daily drinking water is of great significance to ensure that residents’ drinking water does not contain harmful pollutants and is safe to drink.To solve the problems of water quality detection at the end of urban pipe networks and daily drinking water quality detection,and improve the accuracy,sensitivity,and stability of the multi-parameter water quality detection system,the thesis analyzes the domestic and foreign online multi-parameter water quality detection system technology and development status,on this basis,for high precision,high sensitivity,high reliability,intelligent,digital,networking and multi-parameter requirements,An online multi-parameter water quality detection system is designed around four water quality parameters,namely turbidity,residual chlorine,PH value,and temperature.The main work is as follows:Analyze the sensor detection principle and interference problems,and formulate corresponding solutions and structural design.The detection principle of turbidity,residual chlorine,PH value,and the temperature was analyzed.The water turbidity was detected by the scattering method,aiming at the interference problems such as the influence of ambient light,the influence of bubbles in the pipeline,and the serious scattering of the light beams in the detection process of the scattering method.Turbidity detection structure black seal structure design to solve the impact of environmental light,pressure type bubble removal device to solve the impact of pipeline bubble,single and double lens combined beam calibration to solve the serious beam scattering problem;The residual chlorine in the water was detected by electrochemical method.In view of the influence of electrochemical environment temperature on diffusion rate,the stability design of residual chlorine parameter temperature compensation was proposed.The PH value and temperature of water quality are tested by integrated sensor design.The temperature sensor is integrated into the PH sensor to optimize the sensor structure.The key mechanical structure of the multi-parameter water quality test system is designed and the key technologies needed to improve the test accuracy are determined.Design the sensor hardware circuit to improve the accuracy and stability of multi-parameter water quality detection.According to the principle of water quality multi-parameter detection,the driving circuit of the constant light source and the receiving circuit of the light source is designed for turbidity detection.The polarization voltage circuit and the residual chlorine amplification circuit are designed.The PH detection circuit,temperature detection circuit,and central control circuit are integrated and modular design.To realize the real-time transmission and upload of the collected data,this thesis designs a 4G DTU module circuit,which is used to realize the network of the system.Design software programming,drive hardware circuits,and realize data collection and upload.According to the principle of hardware circuit design and detection,the system software is designed to drive the hardware circuit.RT Thread real-time operating system architecture is used to manage and drive task threads,and intelligent design of the detection system is realized.The design of the multi-parameter water quality monitoring platform of the upper computer was studied and realized.The data collected by water quality parameters were received and analyzed and displayed through 4G network,which ensured the intellectualization,digitalization,and network realization of the whole system.Simulate the application scenario of the end flow of the actual pipe network,and conduct calibration and experimental research on the multi-parameter of water quality.The experimental results show that the resolution of turbidity accuracy is 0.001 NTU and the error range is less than 1%.The precision resolution of the residual chlorine sensor is 0.003 mg/L,and the error range is less than 1%.The error range of temperature and PH sensors is less than 0.5%.The online multi-parameter water quality detection system realizes the high precision and stability detection of turbidity,residual chlorine,PH,and temperature,which conforms to the national water quality detection standards of various key technology water quality parameters,and has a good effect on the interference problems and temperature compensation in water quality detection,meeting the application requirements of multi-parameter water quality detection. |
