The challenge

With approximately 40% of the sewers in the city of Gothenburg being combined sewers, rainfall events cause large variations in the hydraulic loading to the Rya water resource recovery facility (WRRF). To fulfil new regulatory requirements, the wastewater treatment plant (WWTP) needed to manage issues related to sewer overflows and to reduce storm weather impacts on the WRRF.

1. Gryaab AB, owner and operator of the Rya WRRF, implemented Future City Flow to increase confidence in decision making, as the effects of control strategy changes can quickly be visualized.
2. An algorithm suggests hourly optimized pumping schemes designed to achieve as stable an inflow to the WRRF as possible.
3. Future City Flow employs data assimilation to adjust the forecast according to identified deviations between measured and simulated values. This is to avoid discrepancies between measured flows and water levels in the sewer network and pumping stations and the corresponding values in the digital twin.
4. After the implementation, Gryaab AB gained a much better understanding of the dynamic behaviour of the tunnel system during high flow events, which helps the operators to make better decisions during critical loading situations, thus helping to comply with regulatory targets. Smart use of the tunnel system reduces combined sewer overflow in the region and will also postpone significant capital investments.