Reducing the hazard of sewage overflows

Using CFD to minimise sewage and storm water contamination of the environment

Like many large cities, the storm water runoff and sewage of Aarhus, Denmark, flow together in a combined drainage system. When a big storm hits the city, some of the excess wastewater goes to the Trøjborg retention basin for storage, until the wastewater treatment plant is able to process it. The Trøjborg basin, however, is situated near the Aarhus Harbour – a popular swimming site. During a severe storm, the contaminants from the wastewater may spill from the basin into the harbour. As part of a research project, we used Computational Fluid Dynamics (CFD) to examine the ability of the Trøjborg basin to settle contaminants in the wastewater. Furthermore, we investigated ways to improve the settling efficiency of the retention basin.