The Process of Model Building and Simulation of Ill-Defined Systems: Application to Wastewater Treatment

In recent years, there has been a growing awareness of the ill-defined nature of environmental processes. To provide a frame of reference for discussions regarding ill-defined systems, a taxonomy and terminology of the modelling and simulation of systems is presented. Due to the complexity of ill-defined systems, it is not only necessary to describe the nature of models, but also to describe modelling procedures. This enables the modeller to obtain the model which best fits his goals (optimal model). For meaningful description of models, different model formalisms will be presented. Furthermore, modelling procedures will be described at a generic level and different model formalisms will be presented. Throughout this paper, Waste-Water Treatment Plants and processes occurring within these plants will illustrate the definitions given.