Environmental aspects of UV-C-based processes for the treatment of oxytetracycline in water

This study is focused on oxytetracycline (OTC) degradation by direct photolysis (UVeC) and photobased advanced oxidation processes (AOPs) (UVeC/H2O2 and UV-C/S2O82-). OTC degradation pathways were revealed by LC-MS/MS and GC-MS/MS analyses. The evolution/degradation profiles of 12 detected byproducts were correlated with changes in biodegradability and toxicity toward Vibrio fischeri recorded during the treatment. Both photobased AOPs yielded higher OTC degradation and mineralization rates than direct photolysis. The OTC degradation pathway was found to be rather specific regarding the main reactive species (HO center dot or SO4 center dot(-))/mechanism, yielding different patterns in toxicity changes, while biodegradability profiles were less affected. Biodegradability was correlated with the observed degradation and mineralization kinetics. The recorded toxicity changes indicate that byproducts formed by initial OTC degradation are more toxic than the parent pollutant. The prolonged treatment resulted in the formation of byproducts that contributed to a decrease in toxicity and an increase in biodegradability, as particularly emphasized in the case of UV-C/S2O82-. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the degradation of oxytetracycline (OTC) using direct photolysis (UV/C) and photobased advanced oxidation processes (AOPs) (UV/C/H2O2 and UV-C/S2O82-). Results showed that AOPs were more effective in OTC degradation compared to direct photolysis. The byproducts formed during degradation had varying impacts on toxicity towards Vibrio fischeri, while the biodegradability was less affected.