Antibiotic contaminated water treated by photo driven advanced oxidation processes: Ultraviolet/H2O2vs ultraviolet/peracetic acid

The release of antibiotics in aquatic ecosystems from the effluents of wastewater treatment plants (WTPs) is of great concern due to possible chronic toxic effects as well as contribution to antibiotic resistance spread. In the present work, the degradation of the antibiotic chloramphenicol (CAP) by ultraviolet (UV)/peracetic acid (PAA) (an advanced oxidation process that has been poorly investigated so far) and UV/H2O2processes as well as its transformation products were studied under different light sources. UV-C/PAA process was found to be effective in the degradation of CAP (half life time (t1/2) = 20 min, initial CAP concentration 25 mg/L), but not effective when solar radiation was used as light source. It is worthy to note that the presence of H2O2in the commercial PAA solution significantly affected the removal efficiency of CAP by UV-C/PAA process. When H2O2was quenched by catalase addition, t1/2increased to 99 min, meaning that PAA can still produce hydroxyl radicals but at a lower rate compared to H2O2. Moreover, process efficiency further decreased in the presence of both solar simulated and natural solar irradiation, being CAP removal also the result of thermal decomposition. The transformation products detected during CAP degradation by UV-C/PAA were different respect to those produced during UV-C/H2O2process. In particular, after 120 min most of the compounds detected presented a molecular weight >300 m/z., meaning that UV-C/PAA process needs more time to degrade the transformation products.