RESUMO
Antibiotic contamination in drinking water has attracted widespread attention. The pollution condition of six macrolide antibiotics (erythromycin-H2[KG-*2/5]O, clarithromycin, oleandomycin, roxithromycin, leucomycin, and tylosin) in two drinking water treatment plants was monitored, and the reaction mechanism of tylosin, a typical macrolide antibiotic, during chlorination disinfection treatment was investigated. The results showed that the six macrolide antibiotics can be widely detected in the drinking water treatment processes; however, their concentrations were generally very low. The concentrations of macrolide antibiotics in the influents and effluents ranged from 0.18 ng·L-1 to 3.97 ng·L-1 and 0.02 ng·L-1 to 1.91 ng·L-1, respectively. The removal rates of the six macrolides in the drinking water treatment were different, ranging from 18% (oleandomycin) to 100% (erythromycin- H2[KG-*2/5]O). The degradation of the six macrolides during chlorination was slow and greatly affected by water quality parameters. The chlorination degradation of tylosin followed the second-order reaction kinetic mode, with the kinetic rate constant of 0.77 L·(mol·s)-1 at pH 7.0. Nine chlorination degradation products of tylosin were detected, and the reaction pathways primarily included tertiary amine hydroxylation, aromatic oxidation, and epoxy addition.
