Induced bank filtration is a key and well-established approach to provide drinking water supply to populated areas located along rivers or lakes and with limited access to groundwater resources. It is employed in several countries worldwide, with notable examples in Europe, the United States, and parts of Africa. Contamination of surface waters poses a serious threat to attaining drinking water standards. In this context, human pathogenic microorganisms such as some viruses and bacteria, originating from the discharge of wastewater treatment plants, form a major contaminant group. A detailed study at an induced bank filtration site along the Rhine river in Germany has now linked transport of bacteria to seasonal dynamics. Key results of the study show that floods should be considered as particular threats, because they can reduce the purification capacity of bank filtration, thus leading to an increase in the concentrations of bacteria in groundwater. Changes in properties of the riverbed sediments over the course of a year can markedly influence the purification capacity of bank filtration and these dynamics may need to be considered in risk assessment practices.
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Source: Phys.org