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The occurrence of five pharmaceuticals (ibuprofen, naproxen, ketoprofen, diclofenac, and bezafibrate) in the influent and effluent water of a sewage treatment plant (STP) in the recipient river water and in a drinking water treatment plant (DWTP) located downstream from the STP was followed during three seasons: winter, spring, and summer. In the STP, the elimination of the pharmaceuticals decreased significantly (an average of 25% compared to spring and summer) in wintertime leading to increased concentrations of pharmaceuticals in the effluent water. The total concentration of all the studied pharmaceuticals in the effluent water was 3-5 times higher in wintertime (about 2500 ng L(-1)) than during the other seasons (about 500-900 ng L(-1)). Accordingly, the highest concentrations (up to 129 ng L(-1)) in the recipient river were measured in the wintertime. Pharmaceuticals were carried longer distances downstream from the STP when the river was covered by ice and snow. During a drastic increase in water flow rate (i.e., during snowmelting), a fast transportation of the pharmaceuticals was observed. The DWTP located downstream from the STP produced water that contained about 8 ng L(-1) of ibuprofen and ketoprofen in the winter sample, whereas in spring and summer the studied pharmaceuticals could not be detected in the drinking water. The results show that cold seasons in boreal areas can severely increase the environmental risk of pharmaceuticals and the risk for contamination of drinking water.

The occurrence of four beta blockers, one antiepileptic drug, one lipid regulator, four anti-inflammatories, and three fluoroquinolones was studied in a river receiving sewage effluents. All compounds but two of the fluoroquinolones were observed in the water above their limit of quantification concentrations. The highest concentrations (up to 107 ng L(-1)) of the compounds were measured during the winter months. The river water was passed to a pilot-scale drinking water treatment plant, and the elimination of the pharmaceuticals was followed during the treatment. The processes applied by the plant consisted of ferric salt coagulation, rapid sand filtration, ozonation, two-stage granular activated carbon filtration (GAC), and UV disinfection. Following the coagulation, sedimentation, and rapid sand filtration, the studied pharmaceuticals were found to be eliminated only by an average of 13%. An efficient elimination was found to take place during ozonation at an ozone dose of about 1 mg L(-1) (i.e., 0.2-0.4 mg of O3/ mg of TOC). Following this treatment, the concentrations of the pharmaceuticals dropped to below the quantification limits with the exception of ciprofloxacin. Atenolol, sotalol, and ciprofloxacin, the most hydrophilic of the studied pharmaceuticals, were not fully eliminated during the GAC filtrations. All in all, the treatment train was found to very effectively eliminate the pharmaceuticals from the rawwater. The only compound that was found to pass almost unaffected through all the treatment steps was ciprofloxacin.