Abstract
A signal processing algorithm for the real-time monitoring of nitrate ions using UV absorption spectrophotometry was developed and applied to the on-site monitoring of nitrate ions in effluent from a sewage treatment plant and influent to a gravel filtration plant for a few months. The algorithm developed can detect a change in the absorption spectrum by interfering substances at UV absorbances of 225,230 and 235nm and correct it in real time by a sequential processing. As the results of the on-site monitoring, this algorithm achieved reliable real-time monitoring of nitrate ions without any additional pretreatment and cleansing of the flow cell. The prediction error during the on-site monitoring was about 1.4 - 4.6 times smaller than that of the conventional method. Turbidity and cloudiness of the optical cell can be apparently regarded as absorption substances. Accordingly, the effects of turbidity and cloudiness of the cell are cancelled by the algorithm developed. Thus, the algorithm developed was considered to be applicable to the real-time monitoring of nitrate ions in terms of high accuracy and easy maintenance.
