Alternating Aeration Control And Optimization In Activated Sludge Processes

The optimization and control of wastewater treatment plants is a very important and challenging issue in modern society. Model based control strategies are developed to control the aeration of an intermittently operated municipal wastewater treatment plant. A hierarchical control framework with two layers is implemented where the lower layer ensures the intermittent aeration sequencing by maintaining the aeration fraction coefficient at the value provided by the optimization level and uses a PID controller to control the concentration of the dissolved oxygen. The higher level uses a model predictive control algorithm to determine the optimal value for the aeration fraction of the aeration cycle. Compared to traditional control systems, the new control techniques exhibit good performances for both setpoint tracking and disturbance rejection within the imposed constraints as well as maintaining the aeration fraction within its constraints.