Sorption and transformation of polar pharmaceuticals during wastewater treatment studied by hollow fiber liquid phase microextraction

Abstract: This thesis addresses the application of hollow fiber liquid phase microextraction as a simple, efficient and environmentally friendly tool to study the fate of four common anti-inflammatory drugs (ketoprofen, naproxen, diclofenac and ibuprofen) during wastewater treatment. Initial experiments verified that this technique is applicable on aqueous as well as suspensions of solid samples, thus greatly simplifying the sample preparation. Initial studies showed that all four of the NSAIDs were present in the influent to Källby wastewater treatment plant (WWTP), city of Lund, Sweden, and analysis in the different sludge fractions revealed that only a minor part (1-13 %) of the analytes partitioned into the sludge. No difference between the partitioning into primary, secondary and tertiary sludge could be observed. However, naproxen and ibuprofen were still efficiently removed, thus indicating major biotransformation. In further studies it was shown that high amounts of eight human NSAID metabolites were present in the WWTP influent, in most cases significantly higher than the NSAIDs themselves. Rather low removal was observed for all compounds in the primary treatment. However, parent compounds as well as metabolites were efficiently removed (> 90 %) during the secondary treatment. Effluent con-centrations were non-detectable or < 1 μg/L for all compounds. Consequently, no indication of formation of the investigated metabolites in the activated sludge process could be found, meaning that the fate of NSAIDs is still unknown. Further work also showed the presence of the four NSAIDs in digested sludge from the same WWTP at the ng/g level. After six months storage, only diclofenac and ibuprofen could be detected in the sludge. When applying this sludge as a fertilizer in the recommended as well as twice the recommended amount, no uptake of these pharmaceuticals into wheat or soybean could be shown. The general conclusion is hence that the major environmental risk associated with NSAIDs is the potential formation of toxic transformation products during wastewater treatment why further studies should be directed towards this field.