| Water is the source of life and nature’s precious asset to mankind.Because of the irrational use of human and the destruction of the ecological environment,the sustainable use of water resources is facing great challenges.The per capita water resources in China are low,the water resources are unevenly distributed,and the water pollution is increasing year by year.This not only exacerbated the shortage of water resources,but also seriously threatened people’s drinking water safety and health.Water pollution and its prevention is no longer a simple environmental problem,but a strategic issue related to the long-term development of our country.Grasp the pollution of water effectively is an important prerequisite for us to draw up practical and effective water treatment plans and take effective measures to protect water areas.Therefore,it is of great significance to improve the water quality on-line monitoring technology and improve the water resources monitoring system.At present,the water quality on-line monitoring is about Station and Buoy,the former develops earlier and is widely used in our country.Its detection principle is mainly Chemical reagent method and it can detect a variety of water quality parameters in real time.But there are many problems,such as complex system,high investment and construction cost,large maintenance,energy consumption and easy to cause two pollution;The buoy type water quality on-line monitoring mainly adopts the spectrum method and the electrode method,It has the advantages of automatic monitoring,less power consumption,low maintenance cost,convenient delivery and no two pollution.Although the buoy type water quality on-line monitoring develop lately,but it grows up rapidly.In this paper,the technical research and design of buoy water quality on-line monitoring sensor have been carried out,and use the spectral analysis method for water quality detection.According to the difference of light absorption characteristics,get the relation between concentration and absorbance of water quality parameters by Lambert-Bill law.And make quantitative analysis of some water quality parameters.The method is very suitable for on-line rapid detection of water quality with no chemical pretreatment,simple operation,short measuring period,especially no two pollution to the environment.Choosing UV-Vis absorption spectrum method for experiments and researches,because the absorption wavelength of many ions in water is in the range of UV visible light.It discussed the influence of turbidity,temperature,other ions and environmental factors on the spectrum detection and studied the the design theory of the sensor signal conditioning circuit.Mechanical structure of single light source and double light source is designed by the function of spectrum,A new method is proposed to adjust the power of the light source by changing the duty cycle to change the range of the sensor.This method changes the traditional method of adjusting the range by changing the optical path of the mechanical structure.A series of experiments were carried out about four kinds of water quality parameters,COD,TP,TN,TOC.Such as signal test experiment,calibration experiment,prototype performance test and actual water sample comparison.The results of experiments are as follows:COD detection’s accuracy in-7.4%-8.1%;TP’s in-5.6%-9.4%;TN’s in-9.0%-9.0%;TOC’s in-4.3%-5.4%;The accuracy of four kinds of water quality parameters is lower than 10%,which basically meets the technical requirements of inspection and the requirements of the national environmental protection standards.Finally,the paper summarized the research work of this subject,and analyzed and prospected the deficiencies. |
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