Analysis, Reinforcement and Estimation of Self-Purification of Polluted Rivers: A System-theoretic Approach

Abstract

A state space model is derived for the water quality equation which describes the behaviors of the BOD and DO concentrations in a river. The water quality equation is given by a couple of second-order linear differential equations with forced terms due to multiple pollutions. Their characteristic equations have both stable and unstable elementary solutions; hence the solutions given by the state space representation should be carefully investigated in order to reflect the natural boundary conditions. Analysis, control and estimation of the self-purification of polluted rivers are investigated with simulation studies.