Seasonal variations of steroid hormones released by wastewater treatment plants to river water and sediments: Distribution between particulate and dissolved phases.

Extensive environmental monitoring was conducted in an urban river impacted by multiple combined sewer overflows (CSOs) and wastewater treatment plant (WWTP) discharge points. Temporal and spatial distributions of dissolved and particulate steroids (progesterone (Prog), testosterone (Testo), medroxyprogesterone (MDRXY-Prog), levonorgestrel (Levo), norethindrone (Nore), estrone (E1), estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2)) were investigated in sewage, WWTP effluents, receiving river water and sediments, and in drinking water plant (DWP) intakes. Steroids were detected in both dissolved and particulate phases with mean concentrations from 21ngL-1 to 389ngL-1 in raw sewage and from 10ngL-1 to 296ngL-1 in treated wastewater. The particle-associated steroids represented 0-82% of their total concentration as some steroids like E1 and E3 were detected only in the dissolved phase while MDRXY-Prog (81%), Nore (71%), and EE2 (>75%) were primarily detected in the particulate phase. Particle-associated steroids were detected in spring samples from river water with mean concentrations ranging from 5.4ngL-1 to 35.7ngL-1 compare to 3ngL-1 to 6.8ngL-1 in summer samples. Levels of particle-associated Testo, Nore, E2 and Levo in DWP intakes (406.2-13,149.1ngg-1) were similar to those found in raw sewage (336.6-7628.8ngg-1), indicating their persistence in the suspended phase from discharge points. Total steroids measured in sediments were in the range of 7-1213ngg-1, 5-25ngg-1, and 22-226ngg-1 in autumn, spring, and summer, respectively. Our findings confirm the presence and seasonal variation of a mixture of particle-associated steroids in drinking water sources. The presence of high concentrations of a mixture of particle-associated steroids in DWP intakes highlight the need for highly effective particle-removal processes to eliminate these recalcitrant compounds during drinking water production. Finally, the detected concentrations raise concerns about their potential environmental effects.