Degradation of pharmaceuticals in municipal wastewater effluents by ozone-based advanced oxidation processes During the last 20 years, the occurrence of pharmaceutical compounds in water bodies has been gaining great scientific attention. Nowadays, there is widespread recognition of their consideration as a relevant environmental problem [1]. As contaminants of emerging concern (CECs), pharmaceuticals are characterized to be biologically active at low concentrations, and once entered into the environment, they can facile bioaccumulate and become potentially hazardous to the aquatic ecosystem and human health [2]. Sources of these compounds usually come from human excretion, where the administered pharmaceutical are passed through the human body unaltered as active ingredients or metabolites [3], and they subsequently enter into the water cycle via wastewater treatment plants (WWTPs). Unfortunately, conventional activated sludge processes employed in WWTPs are not adequate enough to reach high removal efficiencies of pharmaceuticals and, therefore, can be released into the aquatic environment [4]. To minimize their potential impacts, the on-site retention and pre-treatment of HWW have been considered and implemented in developing countries as a solution to decrease the number of pharmaceuticals entering WWTPs. Nonetheless, in many other countries, including Colombia, WWTPS are discharged directly into urban sewerage systems without preliminary treatment. In a worst-case scenario, a common practice is directly discharging raw effluent into surface rivers [8]. Among technologies evaluated for WWTP effluent treatment, ozonation has been demonstrated to be an effective means for the abatement of many pharmaceutical residues. This oxidizing agent has the ability to attack organic compounds directly and selectively at low pH or can undergo decomposition via a chain reaction mechanism that produces hydroxyl radicals (HO•) at high pH [9]. However, due to ozone selectivity, some reaction intermediates are not easily destroyed by this oxidant, leading to very limited mineralization of organic compounds [10]. To overcome this shortcoming, the coupling of ozone with other oxidants, or the combination with a catalyst and/or irradiation, appears to be a promising alternative to increase the mineralization rates and the rate of removal of pharmaceuticals [11]. The thesis proposal attempts to contribute to new results and fill knowledge gaps in the fundamental and practical aspects of ozone-based processes applied for wastewaters treatments plants.