Catalytic ozonation performance and mechanisms of Cu-Co/γ-Al2O3 to achieve antibiotics and ammonia simultaneously removal in aquaculture wastewater

Antibiotics and ammonia are generally co-existed in aquaculture tailwater; moreover, ammonia would also be produced from during ozonation, and should be simultaneously removed before discharge or reuse. In this study, catalyst Cu-Co/γ-Al 2 O 3 was screened from a variety of metal oxides and applied in catalytic ozonation of three kinds of antibiotics and NH + 4 -N. Factors that affected their removal, including catalyst dosages, O 3 concentration, initial pH as well as co-existing ions, were investigated. Moreover, the mechanisms were probed by exploring free radicals’ role as well as intermediates identification; and the characteristics of catalysts before and after use were evaluated using SEM, EDS, XRD, XPS, and BET. Results demonstrated that Cu-Co/γ-Al 2 O 3 could significantly stimulate the degradation of the selected antibiotics and NH + 4 -N during ozonation. The degradation efficiencies of ciprofloxacin (CIP), tetracycline (TC), sulfamethoxazole (SMX) and NH + 4 -N can reach up to 95.0 %, 100.0 %, 96.2 %, and 75.7 %, respectively. Plenty of oxygen vacancy (O vs ) and sufficient alkaline sites on the surface of catalyst facilitated the adsorption of pollutants. Furthermore, the transformation of metal ions Cu + /Cu 2+ and Co 2+ /Co 3+ enhanced the electron transfer capacity and favored the formation of reactive oxygen species (ROS) during catalytic ozonation reaction, and their roles in catalytic ozonation has also been verified. The radical quenching experiments demonstrated that ·OH was the main contributor for enhancing pollutants removal. The results of Gaussian calculation coincided with those intermediates detected by UPLC-Q-TOF-MS, the pollutants’ removal mechanisms by catalytic ozonation were proposed basing on them. The overall toxicities were compared for ozone only/catalytic ozonation by zebrafish embryo experiment. The results of this study would provide new a feasible way for treating antibiotics and NH + 4 -N simultaneously in aquaculture wastewater.