Antibiotics quinolones removal using supported catalysts : Application on hospital wastewaters

L'usage excessif des antibiotiques en médecine humaine et animale pose de graves problèmes environnementaux et de santé publique. L’objectif de cette thèse était d’éliminer deux types d’antibiotiques quinolones pouvant être détectés dans des eaux usées ou effluents hospitaliers. Dans un premier temps, nous avons évalué la réactivité d’oxydes métalliques (fer ou zinc) pour promouvoir des réactions d’oxydation avancée, en présence d’oxydants comme le peroxyde d’hydrogène, le persulfate ou le peroxymonosulfate, et sous irradiation (UVA ou visible). Les oxydes réactifs étaient supportés sur des membranes en acétate de cellulose ou polyester, peu coûteux, respectueux de l’environnement, ce qui permet de fonctionner dans des réacteurs en flux continu à recirculation. L’influence des différents paramètres opératoires (type et quantité de catalyseur, type et quantité d’oxydant, pH, etc.) a été étudiée. L’impact de mélange avec d’autres antibiotiques sur la performance d’élimination a été évalué vis-à-vis de la réactivité de chaque composé avec les espèces radicalaires. Les essais menés sur des effluents hospitaliers ont permis d’identifier des effets compétitifs voir inhibitifs provenant des composants principaux des eaux usées comme les matières organiques, les phosphates et les sulfates ou les chlorures. Les performances observées dans les eaux réelles usées ainsi que les résultats d’évaluation de la réutilisation des solides supportés sont encourageants. Cette étude ouvre la voie à l’application de ce type de réacteur à recirculation intégrant de catalyseurs supportés dans des technologies de traitement des effluents contaminés.The excessive use of antibiotics in human and animal medicine poses serious environmental and public healthissues. The aim of this thesis was to remove two types of quinolone antibiotics that can be detected in wastewater or hospital effluents. Initially, we evaluated the reactivity of metal oxides (iron or zinc) to promote advanced oxidation reactions, in the presence of oxidants such as hydrogen peroxide, persulfate or peroxymonosulfate, and under irradiation (UVA or visible ). The reactive oxides were supported on inexpensive, environmentally friendly cellulose acetate membranes or polyester, which made it possible to operate on a recirculating continuous flow reactor. The influence of the various operating parameters (type and concentration of catalyst, type and concentration of oxidant, pH, etc.) was studied. The impact of mixing with other antibiotics on the removal performance was evaluated with respect to the reactivity of each compound with the radical species. The tests carried out on hospital effluents made it possible to identify competitive or even inhibitory effects coming from the main components of wastewater such as organic matter, phosphates and sulphates or chlorides. The observed performance in the real wastewater as well as the evaluation results of the reuse of the supported solids are encouraging. This study has important implications for possible application of recirculation reactor with supported catalysts in wastewater treatment technologies

Nano-sized iron oxides supported on polyester textile to remove fluoroquinolones in hospital wastewater

International audienceIn this study, we examined the removal kinetics of two fluoroquinolones (FQs), flumequine (FLU) and ciprofloxacin (CIP), in synthetic wastewater (SWW) and real hospital wastewater (RHW) using FeOx thin films, peroxymonosulfate (PMS) and visible light. Nano-sized iron oxides (FeOx) supported on polyester textile (PES) were synthesized by a novel high-power impulse magnetron sputtering (HiPIMS) method. The O-2/Ar ratio is an important factor to tune Fe oxidation, which controls the composition of the thin film and thus the capability of the resulting FeOx for PMS activation. Based on scavenging experiments, sulfate radicals were shown to be predominantly involved in the heterogeneous oxidation reaction. Competitive effects with reactive species could explain the lower degradation rate constants in mixtures relative to those in single systems. In contrast to chlorides, organic matter, sulfates and phosphates commonly found in RHW dramatically decreased the removal performance of both target compounds, FLU and CIP. However, increasing the PMS concentration to 3 mM improved considerably the degradation and mineralization, even in real wastewater. The good stability and reusability of the FeOx/PES material have been confirmed in hospital wastewater over five successive oxidation cycles

Red mud-activated peroxymonosulfate process for the removal of fluoroquinolones in hospital wastewater

International audienceIn this study, a novel peroxymonosulfate (PMS) activation method, which combines a solid waste (i.e., red mud, RM) and a reducing agent (i.e., hydroxylamine, HA), for the oxidative degradation of fluoroquinolones (FQs; i.e., flumequine (FLU) and ciprofloxacin (CIP)) in hospital wastewater (HW) was developed. The addition of HA into the PMS/RM suspension significantly enhanced FLU removal, owing to its ability to enhance the Fe(III)/Fe(II) cycle on the RM surface. The results of the quenching experiments suggested the predominance of SO over OH in the PMS/RM/HA system. Moreover, owing to the greater reactivity between CIP and SO, CIP removal was more effective than FLU removal. Additionally, the liquid chromatography-mass spectroscopy (LC-MS) analysis revealed that the oxidation of CIP and FLU by PMS/RM/HA occurred via sequential and separate processes, involving ring cleavage, hydroxylation, decarbonylation, and defluorination. Surprisingly, the wastewater components exhibited contrasting effects on FLU removal in HW. Natural organic matter, nitrate and sulfate showed a slight impact on the removal performance of FLU, whereas chloride improved the oxidation extent. However, phosphate significantly inhibited the FLU removal because of its competitive binding at the RM surface and its scavenging effect towards SO. This inhibitory effect was overcome by increasing the PMS concentration and its sequential addition, thus guaranteeing successful mineralization of FLU in HW. These results show that the RM/HA system can be utilized to activate PMS for the removal of antibiotics in wastewater