Comprehensive evaluation of pharmaceuticals and personal care products (PPCPs) in urban sewers: Degradation, intermediate products and environmental risk

The release of pharmaceuticals and personal care products (PPCPs) is one of the most concern issues which affect the stability of environment. In this study, the transformation, typical metabolites and risk evaluation of five dominating PPCPs (acetaminophen, triclosan, caffeine, N,N-diethyl-m-toluamide and sulfamethoxazole) were investigated in a pilot sewer. Firstly, the mass balance analysis indicated, although the PPCPs have the peculiarity of degradation-resistant, the biodegradation of PPCPs still plays a more important role in sewers, and then, liquid chromatography coupled to mass spectrometry (UHPLC-Q Exactive MS) methods were utilized to reveal their fate during pipeline transportation. In total, six transformation products (TPs) were detected and identified. The transformation occurring in sewers involved rearrangement of the aminobenzene moiety, ether bond breaking, hydrolysis of hydroxy compounds and dealkylation. Finally, risk(s) were estimated by calculating risk quotients (RQs). TCS is “high risk” (RQ > 200), SMX is “minimal risk” (RQ < 0.3), and the other compounds examined are “low or medium risk” and vary widely (RQ ≈ 3.75–98.19). Thus, based on this investigation, insights into PPCPs bioconversions in sewers were revealed, which could improve the understanding of subsequent treatment process of the wastewater treatment plant (WWTP) and reduced environmental risks caused by micropollutants.