Degradation of the Micropollutant Amoxicillin using Enzymatic Treatment and Evaluation of Resulting Byproducts

Current Brazilian legislation for the treatment of drinking water does not require analysis for micropollutants such as the antibiotic amoxicillin. However, the presence of these compounds in the environment is directly linked to bacterial resistance, and the development of methodologies focusing on their removal is necessary. A few alternatives, such as Advanced Oxidative Processes, have already been proposed and, more recently, studies have shown that certain enzymes, like peroxidases, have the ability to degrade micropollutants in the presence of hydrogen peroxide (H2O2). In this sense, the present study aims to evaluate the enzymatic degradation of 25 mg L-1 amoxicillin using peroxidase. For the specific method, amoxicillin solutions were fed to a batch reactor and different concentrations of peroxidase combined with varying H2O2 concentrations (0.5, 1.0, and 2.5 mmol L-1) were added. Reactions occurred for 9 hours. All samples were analyzed by liquid chromatography coupled with mass spectrometry, and the residual toxicity was assessed using Daphnia magna. The results showed around 50% degradation of the drug, and byproducts originating from amoxicillin were identified. Toxicological tests indicated that the byproducts were minimally toxic to the microcrustacean, highlighting the importance of evaluating the safety of proposed treatments.