Control and operation of wastewater treatment plants (I)

This tutorial is the first part of a review of the problems arising with the control and operation of wastewater treatment plants (WWTP) for urban wastewater. This first part will concentrate in the modelling and simulation steps whereas the second part will cover the control and operation issues. This treatment is carried out, mainly, by biological processes. Specifically, by the so-called activated sludge process. Dealing with a biological process entails a high complexity both from the viewpoint of modelling and, of course, from what matters to control and operation. In order to properly locate the problem, a characterisation of the urban wastewater and the associated treatment needs are presented. Control and operation rely heavily on the availability of appropriate models and, today, of proved reliability. The models of the ASM family are presented; placing special emphasis on the ASM1 that is described in more detail; as well as the characteristics of other process units like the settler and its interconnection. These models highlight the BSM benchmarking environments, which have been essential for all subsequent development in the control and operation activity.