Existence of Pharmaceutical Compounds in Tertiary Treated Urban Wastewater that is Utilized for Reuse Applications

Research on the effects of chemical pollution in the environment that is related to urban wastewaters?? discharge and reuse until recently was focused almost exclusively on conventional pollutants. During the last several years though there has been a growing level of concern related to the hypothesis that various chemicals may exhibit endocrine disrupting effects. In addition, thousands of tons of pharmacologically active substances are used annually ending up in the wastewaters. In many countries facing prolonged droughts and implementing wastewater reuse schemes for irrigation and groundwater discharge, the existence of xenobiotic compounds in the tertiary treated wastewaters constitutes a new concern. This study describes the application of a recently developed multi-residue method for the determination of 29 multi-class pharmaceuticals using off line solid phase extraction followed by liquid chromatography?Ctriple quadrupole mass spectrometry (LC?CMS?CMS). The method was applied for the analysis of pharmaceutical residues at three sewage treatment plants in Cyprus serving major coastal Mediterranean cities. The presence of 19 pharmaceuticals was confirmed. For some of the compounds high concentrations were obtained for the final effluents (e.g. ofloxacin: 4.82 ??g/L, diclofenac: 5.51 ??g/L, carbamazepine: 27.27 ??g/L, metoprolol: 9.59 ??g/L). Concerning the elimination potential, what was derived from the study is that the biological treatment step contributes the most to the removal of the compounds while sand filtration and chlorination steps reduce slightly the residual concentrations.     

Effects of selective water withdrawal schemes on thermal stratification in Kouris Dam in Cyprus

Thermal stratification and its seasonal variations in Kouris Dam in Cyprus were simulated, and the impact of five different water withdrawal schemes was studied, using the 2‐D, laterally averaged CE‐QUAL‐W2 reservoir model. Based on the model simulations, it was found that the thermal stratification of the reservoir is significant for most of the year. Most importantly, a complete mixing of the water column, triggered by seasonal variations in meteorological conditions, occurs in late‐January. Predicted thermal stratification and water temperature profiles in the reservoir are noticeably affected by water withdrawal schemes. It was found that deep‐water withdrawals tend to facilitate heat transfer in the water column and deepen the water mixing layer (epilimnion), especially from September to the following January. These study results suggest that it is prudent for Kouris Dam to integrate selective water withdrawal schemes into reservoir management by using the water withdrawal effects on thermal stratification for different water quality management strategies.