Research Of UV Photoelectric Sensing System On Chemical Oxygen Demand Of Water

In recent years, the attendant environmental problems have become increasinglyprominent as rapid sociol-economic development and the intensification of waterpollution has become a serious threat to people’s lives and living environment. Organicpollution is one of the most serious in the various types of water pollution，it directlyaffects the safety of marine ecology and life, and the most direct reflection of thedegree of pollution among the water quality indicator is the chemical oxygen demand(COD). COD reflects the degree of contamination reducing substances (organiccompounds, nitrites, ferrous salts) in water. It has great practical significance throughdetecting the change of COD to measure the degree of water pollution in the field ofwater quality testing. The paper makes the research based on the principle of CODspectral absorption optical detection theory and develops on the optical sensingsysterm of COD in this paper.The main content of this article includes:Firstly, the paper analyzes the current development of traditional andspectroscopy methods on measuring COD, and presents the principle of the method forthe near-infrared and UV absorption in the measurements of COD，and summariescommonly used algorithms in the processing of spectral data.Secondly, through experiments the paper sets up the UV and NIR quantitativeanalysis model based on standard solution of COD and verifies the accuracy throughpredictive analysis on the test set，establishes UV spectroscopy optical sensing systemfor the design of programs by contrast. The paper studys the influence of turbidity、pH、nitrate and temperature on ultraviolet absorption spectrum and discusses themethods of compensating for the effects.Thirdly, based on the principle of ultraviolet sensor the paper designs the CODonline monitor, describes the optical path and circuit of sensor. The optical design isconsist of the ultraviolet light source，the detector and the light path structure of theproduction. The circuit portion introduces the source driving circuit, the signalamplification circuit, A/D conversion and the liquid crystal display circuit, etc. At last, the paper sets up ultraviolet COD optical sensing system.Finally, the paper builds the quantitative analysis model mainly included lakewater and realised the real-time detection of COD for the actual water samples withthe system of laboratory. Many experimental results verify the feasibility of thesystem.