Schwertmannite catalyze persulfate to remove oxytetracycline from wastewater under solar light or UV-254

Abstract

Oxytetracycline (OTC) pollution has become an important environmental issue. It is an obvious innovation in the field of OTC degradation to comprehensively explore the effect of Schwertmannite (Sch) catalyzed persulfate to degrade OTC under different light conditions, and apply the optimized parameters to remove OTC from actual aquaculture wastewater. Therefore, the effect of sodium persulfate (PS) on the removal of OTC catalyzed by Sch under solar light and UV-254 irradiation was investigated in this study, and the optimized parameters were applied to the OTC removal from actual aquaculture wastewater. The results showed that when 0.8 g/L Sch was added and the concentration of PS was 350 μmol/L, the removal rate of OTC (40 μmol/L) was 89.8% and 92.3% after 3 h and 6 h reactions in dark conditions, respectively. Furthermore, light significantly enhanced the removal efficiency of OTC. The removal rates of OTC in the Sch + PS + OTC system were 96.8% and 99.1% after 3 h and 6 h reactions under UV-254 irradiation, respectively. In addition, it was shown that light accelerated the removal of total organic carbon (TOC); the TOC removal rates after 3 h and 6 h under UV-254 in the Sch + PS + OTC system were 49.8% and 69.7%, respectively. In actual aquaculture wastewater, the removal rates of OTC after 6 h in the Sch + PS + OTC + UV-254 system were 21.7%, 22.7%, 46.1%, 55.1%, 74.1%, 94.5%, and 98.3%, respectively, when the COD concentrations in wastewater were 10,000 mg/L, 5000 mg/L, 2000 mg/L, 1000 mg/L, 500 mg/L, 200 mg/L, and 100 mg/L. The recovery rate of Sch after the reaction in actual aquaculture wastewater was 70.0–99.8%, and the pH after treatment remained neutral. These findings provide theoretical support for the treatment of OTC-containing wastewater via the advanced oxidation technology catalyzed by Sch.