Efficient removal of pharmaceuticals from wastewater: Comparative study of three advanced oxidation processes

As the global consumption of pharmaceuticals increases, so does their release into water bodies. The effects, although not fully understood, can be detrimental to aquatic ecosystems and human health. The new Urban Wastewater Treatment Directive (UWWTD) in European Union requires implementation of quaternary wastewater treatment processes to limit the loads of pharmaceuticals reaching water bodies. In this work, we investigated first the fate of pharmaceutically active compounds (PhACs) in a local wastewater treatment plant (100,000 PE) and their concentrations in effluents during three sampling campaigns. We further assessed removal of these pharmaceuticals by quaternary treatments as well as their energy efficiency. Total concentration of PhAC (27 detected compounds) in influent wastewater was around to 263 μg L^-1, while after wastewater treatment it dropped to 14 μg L^-1 (26 detected compounds). The wastewater treatment plant was effective in removing paracetamol, ibuprofen, naproxen, quetiapine, and ketoconazole, with an efficiency higher than 90%. Nevertheless, post-treatment of its effluents with quaternary treatment technologies will be necessary according to UWWTD. Therefore, we investigated performance of three advanced oxidation processes, i.e. photocatalysis, ozonation and gas-phase pulsed corona discharge-based oxidation (PCD). All methods reached removal efficiency above 90 % for all detected PhACs. PCD process showed the best energy efficiency 0.28 kWh m^-3, followed by ozonation with 0.55 kWh m^-3, while photocatalysis cannot compete with 47 kWh m^-3 of energy required to obtain 90 % removal. PCD was tested for the removal of PhACs mentioned in the new UWWTD. 95 % removal was reached for six selected substances at the delivered energy dose 500 Wh m^-3.