Resumen de Removal of pharmaceuticals in wastewater combining different treatment technologies: suspect screening identification and risk assessment of transformation products
The low efficiency of conventional wastewater treatment plants to achieve the complete removal of micropollutants present, including pharmaceuticals, has motivated the development of alternative water technologies to improve their efficiency, sustainability, and operational costs.
However, even when the complete elimination of these emerging contaminants is attained, these substances can be transformed into new and unknown intermediates which might be even more persistent and toxic than their parent compounds. Up to now, most of the monitoring studies have focused on the removal of pharmaceuticals during wastewater treatments. However, less attention has been paid to the identification of the transformation products generated, their potential environmental effects and their removal. The main inconvenience for their consideration relies on the lack of advanced analytical methods and commercial analytical standards for confirmation of their presence in treated samples. The use of advanced analytical instrumentation based on highresolution mass spectrometry has allowed to cope with this issue providing a simultaneous detection of thousands of substances in a single sample analysis. In this doctoral thesis, the development of advanced suspect screening methodologies has been applied for automatic identification of a wide proportion of the transformation products generated in treated effluents along biological and physical and/or chemical treatments. Additionally, in silico methods and in vitro bioassays based on quantitative structure-activity relationships models, statistical tools and effect-directed analyses were integrated to evaluate the potential environmental effects of transformation products in treated effluents. Finally, these methodologies were applied for monitoring the removal efficiency of pharmaceuticals and their hazardous transformation products in combined treatment technologies. This doctoral thesis demonstrates that target analysis does not provide complete information to draw conclusions about the most efficient water treatment to be applied. The use of advanced suspect screening methodologies for identification of the intermediates generated is highly required. Moreover, this work evidences the high importance of considering their environmental effects of the intermediates generated since some of them may still remain in treated effluents. In conclusion, multidisciplinary research combining analytical chemistry (target and suspect screening analysis), environmental risk assessment and chemical engineering is needed to properly evaluate the best treatment technology to be used.
