Application of SR-AOP for treatment of pharmaceutical wastewater: an interdisciplinary approach for unraveling the full degradation mechanism of representative compounds.

There is a growing concern on the ecological impact of different classes of recalcitrant organic pollutants in natural waters. Many of these organics are toxic and bio-refractory. Pharmaceutical micro-pollutants are regarded as a special threat to ecosystems due to their specific biological effect and the potential of inducing drug-resistant bacteria. Drug residues are only partially removed in a classical wastewater treatment plant and traces are still detected in effluents, surface waters and ground waters.
Some of the major technologies that are currently in the picture for an efficient removal of emerging pollutants are Advanced Oxidation Processes (AOP), which are based on the oxidation of organics by OH-radicals (*OH). Over the past decades, a large amount of experimental data has been generated on the use of these techniques for the degradation of a myriad of organic molecules. More recently, the use of sulphate radical (SO4*-) based oxidation processes (SR-AOP) has gained attention as an innovative alternative for typical AOP processes because of some distinct advantages such as better selectivity and very fast reaction between SO4*- and organic molecules.  SO4*- can be generated via the radical precursors peroxymonosulphate (PMS, HSO5-) and persulphate (PS, S2O82-). To actually generate the radicals (termed activation), different methods have been proposed such as thermal, UV, ultrasound and catalytic (using metal salts) activation.
Information on the actual degradation mechanisms, the influence of the process conditions and the type of radicals involved in degradation by SR-AOP, is scarce and incomplete. Therefore, the main objective of this PhD is to elucidate the full mechanisms behind the degradation of key pharmaceutical products in wastewater by SR-AOP. The approach aims at filling the current knowledge gaps towards degradation of complex organic molecules by employing a combination of process technological research and the development of novel analytical tools/approaches for the identification of the degradation products. This interdisciplinary approach will allow to fully characterize the influence of PMS/PS activation and process conditions on the radical generation and subsequent degradation mechanism. This will pave the way towards an optimization of SR-AOP.