Impact of in-sewer transformation on 43 pharmaceuticals in a pressurized sewer under anaerobic conditions

Abstract

The occurrence of 43 pharmaceuticals and 2 metabolites of ibuprofen was evaluated at the inlet and the outlet of a pressure sewer pipe in order to asses if in-sewer processes affect the pharmaceutical concentrations during their pass through the pipe. The target compounds were detected at concentrations ranging from low ng/L to a few μg/L, which are in the range commonly found in municipal wastewater of the studied area. The changes in concentrations between two sampling points were negligible for most compounds, i.e. from -10 to 10%. A higher decrease in concentrations (25-60 %) during the pass through the pipe was observed for diltiazem, citalopram, clarithromycin, bezafibrate and amlodipine. Negative removal was calculated for sulfamethoxazole (-66±15%) and irbesartan (-58±25%), which may be due to the conversion of conjugates back to their parent compounds in the sewer. The results show that microbial transformation of pharmaceuticals begins in sewer, albeit to different extents for different compounds. Therefore, the in-sewer transformation of pharmaceuticals should be assessed especially when their concentrations are used to estimate and refine the estimation of their per capita consumption in a catchment of interest in the sewage epidemiology approach