The Role of Biofilm on the Fate of Emerging Organic Compounds: Numerical Modelling of Column Experiments

Managed Aquifer Recharge (MAR) is a technology to deal with water stress and water scarcity worldwide. Depending on the origin and degree of prior treatment, the water inflow in MAR facilities contains measurable concentrations of Emerging Organic Compounds (EOCs). Understanding the processes that influence the fate of EOCs in the aquifer is therefore a key point for evaluating and predicting contaminant plumes and risk assessment. Such fate is clearly linked to the presence of biofilms that develop mainly in the first centimeters of the aquifer. Yet, the link between microorganisms, the development of biofilm and the fate of contaminants is not well understood. The spatial distribution into different redox states and thus the taking place of the different redox reactions, which significantly influence the degradation of pollutants as well as the sorption of these substances, is an important point. Sorption takes place in two different phases, the sediment and the biofilm. We have used the results of some conducted column experiments to create a numerical model, with which the processes taking place can be viewed in a differentiated manner and investigated further. The results show that biofilm plays an important role as a sorption phase and should therefore not be neglected when investigating and evaluating the fate of pollutants.