Interval Observer-Based Monitoring of River Water Quality

The monitoring of river water quality plays an important role in the management of the integrated urban water resource. The high non-linearity, time-variability and uncertainty in river systems as well as the problems of high cost and low reliability caused by on-line sensors make it inconvenient to implement online sensors for monitoring river water quality. An interval observer is robust against uncertainties on the kinetics of the process and the additional disturbances on a system. Based on the River Water Quality Model no. 1 (RWQM1) issued by the International Water Association, a software sensor aimed at river water quality was constructed by adopting interval observers, and the operation of the river water quality interval observers were simulated. Simulation shows that this software sensor may give reasonable dynamical bounds respected by the true values of the non-measured variables and realize online accurate monitoring of river water quality even though there exists uncertainty in river inputs caused by the urban wastewater system.