Nonlinear fuzzy control of the dissolved oxygen in activated sludge processes

Wastewater treatment plant is generally a complex, multivariable, time varying and nonlinear large scale industrial system. Moreover, interactions between the components are very strong. The dissolved oxygen tracking problem is one of the most complex and fundamental issues of biological processes. Air for the aerated tanks is supplied by aeration system (blowers, pipes, diffusers). It is a complex dynamic system. The new control strategy for dissolved oxygen tracking in activated sludge processes is proposed. The nonlinear fuzzy PI control system based on Internal Model Control structure is investigated. The inverse model of an aeration system is used for control system design. A control strategy is tested by simulation based on real data records from a case study plant. Promising results are obtained.