A Novel Monitoring System for COD Using Optical Ultraviolet Absorption Method

At present, the monitoring for chemical oxygen demand (COD) is mostly based on the chemical methods. Those instruments are not only with various chemical reagents exhausted, but also long time consumed, the operation procedure and the modification are much professional. This paper reported a novel COD monitoring system using UV-VIS spectrometry. It consists of pulsed xenon lamp, concave holographic grating and the spectral scanning structure, which can obtain any spectral information of water sample in the range of 200-720 nm, corresponding to the COD concentration from 30 to 1000 mg/L through calculating the UV absorbance. With the sample flow cell opened, the instrument can be directly thrown into target water area, without pipeline and control system needed. By using wireless data communications, the system can work continuously at time interval about five minutes. Above all, this instrument is capable of real-time and online monitoring COD and its variations for the surface water such as lakes, rivers and wastewaters.