Geographical and environmental factors in pharmaceuticals and personal care products removal from drinking water plants

Pharmaceuticals and personal care products (PPCPs) are unintentionally released into the environment from treated and untreated wastewater, agricultural runoff, and stormwater, and enter drinking water treatment plants (DWTPs). However, very little is known about the occurrence of PPCPs and their removal effectiveness during the drinking water treatment processes (conventional or advanced treatment) in multiple DWTPs, especially within the same geographical area. To address this important knowledge gap, source and finished drinking water samples were collected monthly from May to September in 2018 and 2019 from four DWTPs in Northern Ohio, USA. The total and individual PPCP concentrations varied among DWTPs and sampling dates in both source and finished water. Despite the site and time differences, caffeine and 17-beta-estradiol were detected at a frequency of 100% in all four DWTPs on all dates, while acetaminophen, estrone and nicotine consistently were not detected. Significant correlations were identified between the source water PPCPs and some environmental variables, such as dissolved organic carbon (DOC), temperature and pH. The PPCP removal efficiency from finished water samples varied depending on DWTP (61.2–84.2%), sampling month (28.3–89.7%), and different PPCP compounds (31.2% and 99.3%). Overall, this study demonstrated that PPCPs were consistently present in low concentrations (ng/L) in the freshwater systems; conventional treatment methods could only partially mitigate PPCP contaminants, while advanced techniques, such as UV-peroxide treatment, provided better removal efficiencies. PPCP removal also depended on the season, with summer demonstrating the highest removal in all four treatment plants.