Study And Design On Chemical Oxygen Demand Measurement Based On Ultraviolet Absorption

With the emergence of adverse environmental problems,people pay more and more attention to the environment.The depletion of natural water resources,the increasing population,the increasing demand for industrial water and household water and other problems,so that the water supply system and water quality is facing severe challenges.Untreated mixed wastewater may be mixed with surface water or used for agricultural irrigation,which poses a serious threat to the entire ecosystem and human health.At present,the incident of small enterprises is serious,resulting in river water pollution,water environment has been seriously damaged,leading to river pollution and a large number of aquatic life,water ecological environment is seriously damaged.Environmental protection departments to determine the focus of centralized regulation and river water on-line monitoring parameters to focus on the secondary control of water pollution.Different enterprises discharge industrial pollutants mixed,so that the water pollutants increased,the water composition becomes more complex,increasing the degree of water pollution.In order to effectively manage the incident of small polluters in sewage,it is necessary to carry out on-line monitoring of sewage pipes in different enterprises within the river basin to monitor whether the waste water discharged from enterprises reaches the national standard comprehensive discharge standard.Therefore,it is necessary to develop more rapid and reliable monitoring technology to replace the traditional water quality parameter measurement.The goal of pollutant discharge control can be achieved by combining the intelligent monitoring technology with the traceability technology and the establishment of a chemical fingerprint information database of emissions related enterprises in the salme basin.This paper introduces the background of the research on the measurement method of chemical oxygen demand,the present situation of the development of the sewage detection,the principle of measurement,and the physical detection method,the method of ultraviolet absorption to detect the chemical oxygen demand.The method is a non-chemical reagent secondary pollution detection method.In this paper,we focus on the detection of chemical oxygen demand by UV absorption method.In this paper,we focus on the detection of chemical oxygen demand by UV absorption method.First,we introduce the measurement principle of UV absorption method.secondly we presents an on-line UV detection method using Czerny-Turner orthogonal double grating structure built optical detection system,the design of optical path and circuit is given,reduces the volume of the measurement system,combines and uses STM32F103 as the core processing chip,proposed and designed a set of chemical oxygen demand concentration detection system,including photoelectric conversion circuit,signal amplifying and filtering circuit and other peripheral circuit.The COD value of the sample was measured by measuring the absorbance value of 254nm and the linear relationship between the concentration of COD and the concentration.Finally,the calibration results of the chemical oxygen demand detection system are analyzed.At the same time,the test and error analysis of the chemical oxygen demand detection system are carried out to improve the accuracy by turbidity and chromaticity compensation.The experimental results show that the COD measurement upper limit is extended to 1 000mg/L,which can overcome the problem of weak light signal and unstable output signal,and realize the accurate measurement of COD in the range of range.Using the results of American Hach Company COD test system,the COD test system has the average measurement error of 8.7%and the reproducibility of COD test system compared with the results of COD detection system of American Hach Company.The range is 0?1000mg/L,the resolution is 0.01 mg/L.The study can achieve the daily drinking water,wastewater treatment of chemical oxygen demand concentration detection and river water pollutants on-line detection.