Paola C. Rúa-Gómez

The occurrence and removal efficiencies of the pharmaceuticals lidocaine (LDC), tramadol (TRA) and venlafaxine (VEN), and their major active metabolites monoethylglycinexylidide (MEGX), O-desmethyltramadol (ODT) and O-desmethylvenlafaxine (ODV) were studied at four wastewater treatment plants (WWTPs) equipped with activated sludge treatment technologies. In parallel to activated sludge treatment, the removal efficiency of the compounds in pilot- and full-scale projects installed at the WWTPs was investigated. Within these projects two different treatment methods were tested: adsorption onto powdered/granulated activated carbon (PAC/GAC) and ozonation. The metabolite MEGX was not detected in any sample. The concentrations of the target analytes in wastewater effluents resulting from activated sludge treatment ranged from 55 to 183 (LDC), 88 to 416 (TRA), 50 to 245 (ODT), 22 to 176 (VEN) and 77 to 520 ng L⁻¹ (ODV). In the pilot project with subsequent treatment with PAC/GAC, the mean concentrations of the analytes were between

The presence of the anesthetic lidocaine (LDC), the analgesic tramadol (TRA), the antidepressant venlafaxine (VEN) and the metabolites O-desmethyltramadol (ODT) and O-desmethylvenlafaxine (ODV) was investigated in wastewater treatment plant (WWTP) effluents, in surface waters and in groundwater. The analytes were detected in all effluent samples and in only 64% of the surface water samples. The mean concentrations of the analytes in effluent samples from WWTPs with wastewater from only households and hospitals were 107 (LDC), 757 (TRA), 122 (ODT), 160 (VEN) and 637 ng L⁻¹ (ODV), while the mean concentrations in effluents from WWTPs treating additionally wastewater from pharmaceutical industries as indirect dischargers were for some pharmaceuticals clearly higher. WWTP effluents were identified as important sources of the analyzed pharmaceuticals and their metabolites in surface waters. The concentrations of the compounds found in surface waters ranged from −1 (ODV) and were dependent on the concentrations of the compounds in the WWTP effluents, the proportion of wastewater in the recipient water, the mean flow rate of the surface water, and the proximity of the sampling point to the WWTP discharge point. The dependence of the concentrations of the target compounds in the surface water on the distance between the sampling points and the points of WWTP discharge into the recipient rivers and streams indicates possible degradation of the compounds in the surface waters. Infiltration of the target analytes into groundwater was not observed.

Some of the pharmaceuticals that are not extensively investigated in the aquatic environment are the anesthetic lidocaine (LDC), the analgesic tramadol (TRA), and the antidepressant venlafaxine (VEN). LDC metabolizes to 2,6-xylidine (2,6-DMA) and monoethylglycinexylidine (MEGX), TRA to O-desmethyltramadol (ODT), and VEN to O-desmethylvenlafaxine (ODV). Within this study, the distribution and behavior of these compounds in German wastewater treatment plants (WWTPs) were investigated. Samples of influents and effluents from WWTPs in Hesse, Germany were collected between January and September 2010. Analytes were extracted from wastewater samples by solid-phase extraction and from solid samples by sonication. Extracts were measured using gas chromatography/mass spectrometry. LDC, TRA, VEN, ODT, and ODV were detected in all analyzed influent and effluent samples. 2,6-DMA could not be identified. MEGX was not detected. TRA and ODV were present in untreated wastewater at the highest concentrations (max, 1,129 (TRA) and 3,302 ng L⁻¹ (ODV)), while the concentrations of LDC and VEN were all significantly lower (mean, 135 (LDC) and 116 ng L⁻¹ (VEN)). All of the analytes were only partially removed in the WWTPs. The mean ratios between the concentrations of the metabolites and their respective parent compounds in influents were 4.7 (ODV/VEN) and 0.7 (ODT/TRA). These values remain approximately constant comparing influents and effluents. LDC, TRA, VEN, ODT, and ODV are only partially removed from sewage water by WWTPs and thus are continuously discharged in respective recipient rivers. A further transformation of TRA and VEN into the known metabolites during treatment in the WWTPs is not observed.