In a combined sewer, the sewer system collects both wastewater and surface runoff (rainwater). If there is strong rain and the wastewater treatment plant cannot treat all the wastewater (mixed with rain water), part of the wastewater will be discharged directly to the nearby streams, rivers, and other water bodies. This is called combined sewer overflow (CSO). In Europe, people are allowed to swim in certain rivers. However, after periods of intense rain the water quality is expected to be not suitable for swimming due to CSO and microbiological contamination. It is therefore of research interest to study when the river water is clean again after intense rainfall.
Fecal indicator bacteria (FIB) such as Escherichia coli (E. coli), are accepted indicators of microbiological contamination and can be used to evaluate the microbial water quality after rainfall. There are still knowledge gaps surrounding the hydraulic parameters on the fate and transport of E.coli.
- build a proper experimental setup,
- perform several experiments to understand the influence of hydraulic and some physico-chemical parameters on
the survival rate, suspension and sedimentation of E.coli.