Study On Determination Of Chemical Oxygen Demand By UV Absorption Spectrum And BP Artificial Neural Networks

At present, the principle of design for COD automatic on-line monitoring instruments are mostly based on the national standard method in China. That is to simulate traditional wet chemical method to make analytical process become on-line analysis. The analytical period is long for the sample still has to be heated and digested before; what's more, many reagents are used in these methods and pipelines and volves are introduced in this system, which are complex and difficult to operate and maintain; furthermore, eluting waste water causes terrible second pollution. So , it is of great significance to develop quick simple and convenient water COD automatic on-line monitoring instrument.The concentration of COD in waste water depends mainly on the composition and concentration of its organic substances. Some researches had indicated that most organic substances have strong absorption at ultraviolet region. Under certain conditions, the absorption and the COD of organic substances have good correlation which can be used to determinate COD directly by UV absorption. It is a quick and simple measuring method, in which chemical reagents are not used and samples need't to be heated.This paper starts with organic substance's ultraviolet absorption spectrum and chose some organic substances which have certain representativeness. The correlation between ultraviolet absorption law and organic matter content are disscuseed and BP-ANN (Back Propagation Artificial Neural Network) are used to...