Design Of Small Mobile Water Quality Information Monitoring System Based On Spectrometer

In recent years,our country attaches great importance to water resources management.The quality of water resources is related to the national economy and people's livelihood.Water quality parameter testing is the basis for water resources management and prevention,and is an important means to understand the quality of water.In terms of conventional water quality testing,COD,turbidity,temperature,and pH are important parameters for water quality.For turbidity,temperature,and pH,it can be detected by physical methods.For the detection of COD,most of the domestic methods are still analyzed by traditional chemical methods.The chemical method detection is not only poor in real-time performance,but also has a single detection parameter.The detected waste liquid is difficult to handle,and it is easy to cause secondary pollution.In order to realize green and real-time monitoring of water quality parameters,this thesis proposes and designs a multi-parameter water quality monitoring system equipped with ultraviolet-visible band spectrometer.The multiparameter water quality monitoring prototype developed by this subject can not only realize the on-line measurement of COD and turbidity by absorption spectroscopy,but also use sensor data acquisition technology to simultaneously collect temperature,pH and GPS geographic location.This water quality monitoring prototype has a good market application prospect.This subject mainly studies and trials the multi-parameter water quality monitoring prototype.The research content mainly includes two parts of hardware and software.A set of optical path systems and circuit systems are designed on the hardware.The optical path system is mainly composed of low-voltage tungsten light source,cuvette,fiber optic spectrometer,etc.,and is responsible for absorbance experiment and spectral data acquisition.The circuit system is mainly composed of STM32 MCU and various sensors and peripherals,and is responsible for controlling data acquisition and data transmission and reception.The software part mainly studies the program design and function implementation under the two development environments of Keil and LabVIEW.Based on the program design in the Keil development environment,the lower computer is used for data acquisition,reception and transmission through the controller.The program design based on LabVIEW development environment realizes the command transmission and data receiving,processing,display and saving functions of the lower computer.In this thesis,the absorbance test of different concentrations of potassium hydrogen phthalate solution was carried out,and the relationship model between the COD concentration and the absorbance of the solution at 254 nm was established.The turbidity influencing factors were analyzed experimentally.The absorbance characteristics of turbidity and turbidity liquid at 254 nm and 546 nm were established by the absorbance characteristics of diatomite turbidity liquid at 254 nm and 546 nm.The effects of temperature and pH changes on the absorbance of potassium hydrogen phthalate solution,humus soil solution and field water samples were investigated,and a dual-wavelength detection model with turbidity compensation was established for the detection of chemical oxygen demand parameters.The water samples from different sources were tested by using the prototype developed by this subject,and the measured values of COD and turbidity were compared with the results of the national standard method.The results show that the instrument is for general surface water.The COD value and the turbidity value have more accurate measurement results.Finally,the field work was tested using a prototype and the source of the error was analyzed.The prototype developed by this project has the advantages of multi-parameter synchronous monitoring,green environmental protection,miniaturization,etc.It is suitable for river water quality monitoring,municipal water supply monitoring and other occasions.