Role of Soil Biofilms in Clogging and Fate of Pharmaceuticals: A Laboratory-Scale Column Experiment

Contamination of groundwater with pharmaceutical activecompounds(PhACs) increased over the last decades. Potential pathways of PhACsto groundwater include techniques such as irrigation, managed aquiferrecharge, or bank filtration as well as natural processes such aslosing streams of PhACs-loaded source waters. Usually, these systemsare characterized by redox-active zones, where microorganisms growand become immobilized by the formation of biofilms, structures thatcolonize the pore space and decrease the infiltration capacities,a phenomenon known as bioclogging. The goal of this work is to gaina deeper understanding of the influence of soil biofilms on hydraulicconductivity reduction and the fate of PhACs in the subsurface. Forthis purpose, we selected three PhACs with different physicochemicalproperties (carbamazepine, diclofenac, and metoprolol) and performedbatch and column experiments using a natural soil, as it is and withthe organic matter removed, under different biological conditions.We observed enhanced sorption and biodegradation for all PhACs inthe system with higher biological activity. Bioclogging was more prevalentin the absence of organic matter. Our results differ from works usingartificial porous media and thus reveal the importance of utilizingnatural soils with organic matter in studies designed to assess therole of soil biofilms in bioclogging and the fate of PhACs in soils. This study reports biosorption for pharmaceuticalsof differentspeciation and a reduction of clogging in the presence of soil organicmatter.