Antidepressants in urban wastewater treatment plant: occurrence, removal and risk assessment

In this study, an analytical methods for determination of antidepressants including (diazepam (DZP), lorazepam (LZP), carbamazepine (CBZ), fluoxetine (FLU)) was developed. The concentration of antidepressants was monitored in Konya Urban Wastewater Treatment Plant influent and effluent samples for one years.  Environmental risk assessment was performed with detected concentration with treatment plant effluent wastewater by hazard quotient (HQ) methods. Oasis HLB cartridges with SPE system was used for extraction of wastewater samples. The effect of sample volume and pH, different analyte concentration, pretreatment and matrix on efficiency of cartridges were optimized. Quantitative analyses of the target compounds were performed by LC/MS-MS system. Recoveries of antidepressant compounds from fortified wastewater were over 87% for three different fortification levels. The limits of detection were determined between 0.006 and 0.118 ng l-1. CBZ, FLU and LZP concentration in influent varied from 6.3 to 135.6 ng l-1, <dl to 2.6 ng l-1, <dl to 4.8 ng l-1, respectively, while DZP was not detected. CBZ, DZP, FLU and LZP concentrations in the effluent was determined as <dl-245.1 ng l-1, <dl-0.21 ng l-1, <dl-2.7 ng l-1, <dl-2.2 ng l-1, respectively. Antidepressants were generally removed in January, February, and August. The high removal was determined for CBZ compounds as %100 at January. The low removal was determined for FLU compounds as %2.4 at January.

While the HQ values for DZP, LZP, CBZ were determined below 0.1 which means insignificant risk to aquatic organisms, HQ values for FLU determined above 0.1 which means low risk to aquatic organism