Adaptive lambda-tracking control of activated sludge processes

An adaptive controller for activated sludge processes is introduced. The co ntrol objective is to keep, in the presence of input constraints, the conce ntration of the biomass proportional to the influent flow rate, where a pre specified small tracking error of size lambda is tolerated. This is achieve d by the so called lambda -tracker which is simple in its design, relies on ly on structural properties of the process and weak feasibility properties, and does not invoke any estimation or identification mechanism or probing signals. lambda -Tracking is proved for a model of an activated sludge proc ess with unknown reaction kinetics and including unknown time-varying proce ss parameters. It is illustrated by simulations that the lambda -tracker wo rks successfully, and even under practical circumstances which go beyond wh at we can prove mathematically, it can cope with 'white noise' corrupting t he measurement and periodically acting disturbances.