Abstract
A procedure is described for designing a digital controller for maintaining the level of dissolved oxygen in a polluted river. The controller generates discrete-time profiles for aeration input and rate of effluent discharge which are used as the controls. Simulation results show that the digital controller performs quite well compared to the continuous-time controllers described in an earlier paper (Gourishankar and Ramar 1977). Computer simulation results are presented to show that the digital controller, designed on the basis that the river system model parameters are constant, performs well with seasonal temperature variations which affect the model parameters.