High gain observer for nonlinear system: Application to system of waste water treatment

In this paper, observers design for a class of nonlinear systems has been investigated. Over the last decades, tremendous research activities focus on observer design for nonlinear systems can be shown through the vast literature in this field. Also, waste water treatment process models have become a major tool to design control schemes. So, a model of waste water treatment plants was developed to describe the concentration's behavior. And the nonlinear observer is applied to estimate the states in system of waste water treatment plants whose substrate concentration and biomass concentration.