ONLINE ESTIMATION OF THE RESPIRATION RATE IN AN ACTIVATED-SLUDGE PROCESS

In this paper, a novel approach to estimate the respiration rate in an activated sludge process is developed. The proposed estimator for the respiration rate is simple to implement and can be used during normal closed loop control of the dissolved oxygen. The basic idea is to use a two step procedure where in the first step, a model of the oxygen transfer rate K(L)a is estimated from a data set. The nonlinear K(L)a function is modelled with a static, constrained, piecewise linear model. In the second step, the respiration rate is estimated from measurements of dissolved oxygen concentration and air flow rate using the K(L)a model obtained in step 1.