Author(s): Kordula Schwarzwalder; Minh Duc Bui; Peter Rutschmann
Linked Author(s): Peter Rutschmann
Keywords: Fecal indicator bacteria; Numerical simulation; Water quality
Abstract: Water quality has been an important point since some time, but we get even a tighter focus on it due to climate change. Also the EU-Water Framework Directive enhanced the interest in this topic. Even in rivers with a good quality we can have some incidents, like an inlet of untreated wastewater, which can decrease the quality. After heavy rainfalls we can find a noticeable amount of fecal indicator bacteria (FIB) in rivers due to an overflow of combined sewer systems. In this kind of sewer system e. g. a thunderstorm can cause an intake of mixed rainwater, urban runoff and wastewater directly into the river system. A high amount of bacteria is discharged and the water quality in the river therefore is decreasing. Better information about the processes and the development of tools to describe these processes are necessary to achieve a better prediction of water quality. Our approach is to get more knowledge about the fate and transport of bacteria in the river Isar, especially the interaction with the biofilm, which has a major influence on the processes. The bacteria we focus on are E. Coli and Enterococci. Both are very common in urban wastewater and therefor FIB. As part of this research work we did experiments in a flume in the outside area of our laboratory, the Oskar von Miller institute, to get more information about the sedimentation and resuspention of the FIB under natural conditions. This also includes UV inactivation and other real life influences. The data we received in our experiments is used in our computational model to simulate and subsequently predict the fate and transport of the FIB. We use Flow3D for the simulation of hydraulics.