Photocatalytic degradation of pharmaceutically active compounds (PhACs) in urban wastewater treatment plants effluents under controlled and natural solar irradiation using immobilized TiO2

Abstract The degradation of pharmaceutically active compounds (PhACs) under controlled and natural solar irradiation using immobilized TiO2 was studied in model solution and real urban wastewater effluents. The TiO2 coatings were prepared via the sol–gel method with two different configurations, using simple (thin films) and the “sandwich” approach. Prepared coatings were characterized employing X-ray diffraction (XRD), scanning electron microscopy (SEM), ellipsometry and UV–Vis diffuse reflectance spectroscopy. Decomposition of PhACs detected in urban wastewater effluents (diclofenac, carbamazepine, atenolol, propranolol, albuterol, ofloxacin, ciprofloxacin, azithromycin, erythromycin, hydrochlorothiazide, and furosemide) was monitored using Ultra Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry (UPLC-QqQ-MS/MS). Among detected PhACs three are included in the Watch List (EU Decision 2018/840). The “sandwich” coatings (deposited on frosted support) with the following structure: anatase layer, TiO2 P25 nanoparticles and anatase layer (sealing film) demonstrated the highest photocatalytic activity among all tested TiO2 coatings and were used for elimination of PhACs from real urban wastewater effluents. Photocatalytic treatment of urban wastewater effluents under controlled and natural solar irradiation led to moderate and high removal (>40%) of all detected PhACs except carbamazepine and atenolol, for which poor removal efficiency was observed (~20%). Some of the PhACs compounds present in wastewater effluents, such as diclofenac, ofloxacin, ciprofloxacin, hydrochlorothiazide and furosemide were sensitive to solar photolysis. The efficiency of solar photocatalytic inactivation of Escherichia coli present in urban wastewater effluent was similar to that of solar disinfection (SODIS).