Have you ever asked yourself; what are the secrets of modelling wastewater treatment plants WWTPs? How to model WWTP? What is the meaning of modelling and simulation? Is it easy? How to start? What are the tools to be used? What is the information you need? What is the software applicable? What are the limitations! Here’s the solution. This thesis provides quick and advanced methods to help you model WWTPs. Try and don’t hesitate. After while, you can model any WWTP easily! You will be a unique pioneer in this field.