| The safety of drinking water is of great importance.And it is extremely important to qualitatively and quantitatively detect the parameters of drinking water quality.DOM(Dissolved Organic Matter)is a typical parameter that reflects the content of organic matter in water.TDS(Total Dissolved Solids)is a typical parameter that reflects the content of ions and minerals in water.Fluorescence spectrum analysis technology can be used to detect DOM parameter because of its non-polluting and high efficiency.And TDS can be obtained by detecting the conductivity of water.In order to meet the needs of water quality parameters detection,this paper designed a small drinking water quality parameters detection system.Use a laser to excite the water sample to produce fluorescence.Then split the fluorescence to get the fluorescence spectrum.Finally,the relative value of DOM will be obtained based on the intensity of the characteristic fluorescence peak.TDS is calculated by conductivity.The above test results are displayed on the OLED screen.The specific research contents are as follows:(1)The fluorescence firstly passes through the collimation system,then the beam passes through the grating to be separated.Finally,the lens is used for focusing so that subsequent detectors can collect.(2)The hardware circuit mainly realizes the functions of laser drive,data acquisition and real-time display.The laser drive circuit can drive a 405 nm semiconductor laser to emit a stable laser.The acquisition and conversion circuit includes two parts.One part uses an analog CCD camera to acquire the fluorescence spectrum image,then the decoding chip decodes the analog video signal.The other part is the TDS detection circuit,which mainly detects the conductivity of water.MCU core circuit controls the entire acquisition,conversion and transmission process.The real-time display circuit is mainly to drive the OLED screen for real-time display.(3)The software design mainly includes three parts: driver,acquisition control flow,and data processing algorithm.Drivers include MCU peripheral configuration,decoding chip configuration and other peripheral circuit drivers.Using MCU’s interrupt and DMA functions to collect data according to reasonable timing.Converting the collected fluorescence spectrum images into spectrum curves,and calculating the relative intensity of DOM.In addition,the 12-bit ADC of the MCU is used to collect the relevant voltage of the TDS detection circuit,and the TDS value is calculated by the voltage division method.Experiments show that the small portable drinking water quality detection system studied in this paper can accurately and effectively detect the content of DOM and TDS in water samples.Compared with the traditional chemical method to detect the content of DOM,the fluorescence spectrum analysis technique used in this paper is more convenient and quicker,and it has no pollution to the water sample.Compared with common water quality detection pens on the market,generally only the inorganic substance parameters such as TDS can be detected,but the DOM detection function is lacking. |
