Model reduction and robust control of the Activated Sludge Process

The Activated Sludge Model no. 1 (ASM1) [6], which is the most widely accepted model of wastewater treatment plants (WWTPs), is used to describe the biotrans-formation processes of nitrification-denitrification. Due to its complexity and nonlinearity, this model is however not well-suited to the design of a control structure. The objective of this work is threefold: (1) to reduce the ASM1, (2) to linearize the reduced model, and (3) to design a robust control algorithm, in order to improve the plant performance and reject disturbances. This procedure is illustrated with data from the COST benchmark [7].