Modelling and real-time control of the integrated urban wastewater system

In the European Union, the Water Framework Directive (WFD) enforces a good ecological and chemical status of all surface waters. In-stream (immission) concentrations and populations need to comply with certain standards. In order to deal with this new legislation, integrated urban water management is an important issue. Real-time control (RTC) is one approach that may be used to improve the performance of the system. Immission-based RTC has been suggested as a proper instrument to help fulfilling the WFD requirements. In order to design and tune an immission-based RTC scheme and to judge the overall effect on the receiving water, an integrated mathematical model of the urban wastewater system is necessary. Several problems are encountered when creating such a model and solutions are discussed in this paper. With this integrated model, an immission-based control strategy is developed for a particular case study and is shown to be able to improve the water quality compared to the uncontrolled case. In the final part, the robustness of this control strategy is tested, as an important additional measure of performance. It can be concluded that there are tools available to help dealing with the operational consequences of the WFD.