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

•Simultaneous removal of OTC and P was inspected by O3/CaO2 advanced oxidation process.•The removal efficiency of OTC and P reached 98.0 % and 90.5 % respectively with 0.80 g/L CaO2 and 0.50 g/h O3.•·OH, ·O2−, 1O2 made major contribution to the degradation of OTC in O3/CaO2 system.•Two main degradation pathways of OTC were proposed based on LC-MS and DFT analysis.•The toxicity of co-pollution of OTC and P was significantly declined after O3/CaO2 treatment.