Water quality-based real time control of integrated urban drainage: a preliminary study from Copenhagen, Denmark

Global Real Time Control (RTC) of urban drainage systems is increasingly seen as cost-effective solution for responding to increasing performance demands. This study investigated the potential for including water-quality based RTC into the global control strategy which is under implementation in the Lynetten catchment (Copenhagen, Denmark). Two different strategies were simulated, considering: (i) water quality at the wastewater treatment plant (WWTP) inlet and (ii) pollution discharge to the bathing areas. These strategies were included in the Dynamic Overflow Risk Assessment (DORA) RTC strategy, which allows for prioritization of the discharge points in the systems according to their sensitivity. A conceptual hydrological model was used to assess the performance of the integrated control strategy over an entire year. The simulation results showed the benefits of the proposed approaches in reducing Combined Sewer Overflow (CSO) loads at the WWTP inlet and in an upstream location discharging to sensitive bathing waters for medium CSO events (i.e. those with greater potential for control). Furthermore, when looking at the overall performance across the entire catchment during the simulation period, no significant changes were observed. These preliminary results require further analysis by including detailed water quality measurements and simulations. Nevertheless, the potential for including water-quality RTC in global RTC schemes was unveiled, providing a further option to urban water managers to improve the performance of their systems.