EXPOSURE ASSESSMENT OF PHARMACEUTICALS IN WASTEWATERS AND SURFACE WATER - THE CASE STUDY OF THE CATCHMENT AREA OF FERRARA

This study deals with the occurrence (exposure assessment) of 11 antibiotics for human use and an anti-epileptic drug in raw and treated urban wastewater and in surface water. The monitored compounds were: clarithromycin, azithromycin, roxythromycin, erythromycin, ciprofloxacin, norfloxacin, ofloxacin, doxycycline, tetracycline, metronidazole, trimethoprim and carbamazepine. The area selected for the study was the catchment area of the wastewater treatment plant (WWTP) of Ferrara (Northern Italy), and the receiving water body for the treated effluent from the WWTP. WWTP Ferrara is a conventional activated sludge plant that releases effluent into a local surface water body network used for irrigation purposes. The monitoring study was carried out in March 2010 and in May 2011 in order to investigate the occurrence (i.e. measured environmental concentrations - MECs) of the selected compounds in the three sampling points: influent and effluent of the WWTP and the receiving surface water body. Besides, predicted environmental concentrations (PECs) of the compounds, for the same sampling points, were estimated based on local consumption of pharmaceuticals as suggested by European Medicine Evaluation Agency (EMEA, 2006). Main Results and Brief Summary of the Discussion Topics All the se lected compounds, except doxycycline and tetracycline, have been detected in the influent and effluent samples in concentrations ranging from 42-2212 ng/L and 23-638 ng/L, respectively. Only five compounds were detected above their detection limits in the surface water samples: clarithromycin, azithromycin, ciprofloxacin, trimethoprim and carbamazepine; where they were present in concentrations between 2 and 25 ng/L. The comparison between predicted and measured concentrations shows that quite often, in the influent and in the effluent of the WWTP, PEC is higher than MEC, with few exceptions: PEC provides a good approximation for 4 out of 12 compounds (i.e. azythromycin, roxythromycin, ciprofloxacin, norfloxacin). While PEC for erythromycin, ofloxacin, metronidazole were two orders of magnitude lower than the corresponding MEC, PECs for clarithromycin, trimethorpim and carbamazepine were always one-two orders of magnitude higher than the corresponding MEC in influent an d effluent wastewater. Surface water PECs were always about 1-2 orders of magnitude higher than the corresponding MECs. This study also discusses the reasons for such discrepancies between PECs and MECs and presents a comparison with the results obtained in similar studies in some European countries. Moreover it focuses on the importance of the characteristics of the receiving water body and how environmental characteristics may contribute in mitigating the impact of the release of these recalcitrant compounds. Finally the removal of the target compounds in the WWTP has been discussed, as well, and compared with available literature data