Occurrence, drivers, and risk assessment of non-antibiotic pharmaceuticals in urban sewer systems

To explore the spatiotemporal distribution of non-antibiotic pharmaceuticals (Non-Anti-PHAs) in urban sewers, a segment of the sewers in Harbin, located in northeastern China was selected. Sewage samples were collected from 23 inspection wells during three sampling campaigns in winter (January), spring (May), and summer (August) of 2022. Results revealed the order of Non-Anti-PHAs average levels (ng/L) was Antidiabetic drugs (3170) > Stimulants (2440) > Antihypertensive drugs (1780) > Antipyretic & Analgesic drugs (AAs, 1760) > Stimulant metabolites (1020) > Lipid-lowering agents (106). No evident seasonal variations were observed for Stimulants and Antidiabetic drugs in sewer sewage. However, AAs, Antihypertensives, and Lipid-lowering agents showed a seasonal pattern with peak concentrations in summer, followed by spring, and the lowest levels in winter. The concentration distributions of Non-Anti-PHAs all followed a positive skewness (skewness >0), but significant differences in kurtosis and skewness were observed between drug categories, which may be linked to their different sources and transformation behaviors within the sewage system. Hospital wastewater could be an important point source of Non-Anti-PHAs in sewer sewage, with drug concentrations in sewage located further from hospitals being approximately 50 % of those near hospital areas. Population-normalized daily loads (PNDLs), calculated from drug concentrations, reflect local residents' medication consumption habits. The correlation between PNDLs of different Non-Anti-PHAs may be related to polypharmacy practices. A significant negative correlation was observed between metal ions (such as Sr²⁺, Ca²⁺, Mn²⁺, Ba²⁺, and Al³⁺) and Non-Anti-PHAs concentrations in the sewage, likely due to their shared adsorption to sediments in the sewers. Antihypertensive drugs in urban sewer sewage displayed ultra-high risks (100 ≤ RQ < 1000). The findings of this study provide key insights into the emerging trends of pollutants in sewer sewage and contribute valuable information for the establishment of wastewater management priorities.