Simultaneous degradation of antibiotic and removal of phosphate in water by a O3/CaO2 advanced oxidation process

The simultaneous presence of antibiotics and phosphate (P) in wastewater will threaten human health and ecological security. The purpose of this study is to study the simultaneous removal of oxytetracycline (OTC) and P in water by O3/CaO2 advanced oxidation process. With enhancing CaO2 dosage, the degradation efficiency of OTC first improved and then declined, whereas the removal efficiency of P kept increasing. Increasing the amount of O3 increased the removal efficiency of OTC, but had little effect on the removal efficiency of P. With 0.80 g/L CaO2 and 0.50 g/h O3, the removal efficiency of OTC and P reached 98.0 % and 90.5 % respectively. The lower OTC concentration was beneficial to OTC degradation and P precipitation. The P concentration has no effect on OTC degradation, but it would affect itself precipitation. Alkaline environment was conducive to OTC degradation and P removal. ·OH, ·O2−, 1O2 made major contribution to the degradation of OTC, which was verified by ESR technique and free radical capture experiment. During the degradation of OTC and P removal, TOC and COD values decreased, while pH and conductivity showed a downward trend. Based on UV–Vis spectrum, 3D EEMF spectrum and LC-MS analysis, two main degradation pathways of OTC were proposed. Toxicity analysis of intermediates showed that their toxicity was significantly lower than that of OTC. The O3/CaO2 system can be considered as an efficient and prospective method for the simultaneous removal of OTC and P in water.