Predictive models for the degradation of 4 pharmaceutically active compounds in municipal wastewater effluents by the UV/H2O2 process

Abstract

Pharmaceutically active compounds (PhACs) have been frequently detected in aquatic environment and raised concerns because of their environmental persistence and potential ecological risk, especially carbamazepine (CBZ), erythromycin (ERY), atenolol (ATL) and clofibric acid (CA). The UV/H2O2 advanced oxidation process was considered as an effective process to remove pharmaceuticals in wastewater. Because of the diverse structure of pharmaceuticals and the various wastewater matrices, this study established two models to predict the degradation of 4 PhACs in wastewater by UV/H2O2. Besides, the degradation pathway and toxicity of 4 PhACs by UV/H2O2 were explored. The degradation of 4 PhACs by UV/H2O2 followed the pseudo first-order kinetics pattern. The degradation rate of pharmaceuticals decreased as CBZ > ATL > CA > ERY. A kinetic model combining the steady state concentrations of HO∙ successfully predicted the degradation process of pharmaceuticals in 14 secondary municipal wastewater effluents. Also, a water matrix prediction model by response surface methodology (RSM) was established to estimate the degradation of pharmaceuticals well. A detailed and systematic comparison of two models in the objectives of models, predicting target contaminants, types of wastewater and parameters of models was made. In addition, the tentative transformation pathways of 4 PhACs by UV/H2O2 were proposed. 4 PhACs after UV/H2O2 treatment enhanced the toxicity, and prolongation of treatment time can reduce the toxicity on the luminescence.