The contribution of soil passage in removing pharmaceutical compounds from infiltrated surface water

Climate change is expected to result in reduced discharge volumes, especially during summer and autumn. Consequently, an increase in pharmaceutical concentrations is expected in surface waters. In addition, an increase in the concentrations of current and newly developed pharmaceuticals is expected following a consumption increase due to population ageing. In many cases, current treatment plants that rely (in part) on surface water for the production of drinking water are facing difficulties removing pharmaceuticals and their transformation products from the water. It is known that part of the removal of these compounds already occurs during soil passage, e.g. during riverbank or dune filtration. The degree to which these substances are removed will depend on the compound characteristics and the site-specific conditions for soil passage, such as redox system and travel times. However, insight into the quantitative extent to which this aquifer-treatment contributes to overall removal and how this varies for various compounds at varying location-specific conditions have been largely lacking so far. In our study, a large database of pharmaceutical concentrations from 5 different recharge systems was used to make a comprehensive estimate of the removal of pharmaceuticals along soil passage after bank or basin filtration.