Natural attenuation of pharmaceuticals and personal care products percolating through rocky substrates – an example based on the Káraný waterworks

This survey focused on a detailed analysis of the ability of fluvial Quaternary sediments to remove pharmaceuticals and personal care products (PPCPs) from drinking water. Thirty-eight PPCPs were detected in the Jizera River, which is used after infiltration to produce drinking water by the Káraný waterworks. Several PPCPs occurred in the water at concentrations exceeding 100 ng/l, some of which are not possible to remove (oxypurinol, acesulfame). The presence of PPCPs was monitored after infiltration and during passage through sandy gravels to the receiving well (total distance of 180 m) at monthly intervals in 2022–2023. PPCPs can be divided into different groups based on the results. Iohexol, iopromide, metoprolol, cetirizine, valsartan and clarithromycin were already below the established threshold after passing through 60 m of gravel. Other substances were gradually attenuated and a diverse group of PPCPs remained in the groundwater even after passing through 180 m of subsoil. Surprisingly, the PPCP with a high degree of attenuation, such as metformin, whose concentration drops from the original value of 677 ng/l to 16 ng/l, was in this group. The member of this group with lowest degree of attenuation was sulfamethoxazole with a value of 9%. Five substances (benzotriazole, propylparaben, bisphenol S, hydrochlorothiazide, ibuprofen-2-hydroxy) were identified as the most problematic since they passed through the quaternary fluvial aquifer practically unchanged and the process of qualitative treatment using artificial infiltration appears to be ineffective.