Waste control by waste: A new approach for antibiotic removal and metal reuse from livestock wastewater using ascorbic acid-enhanced CaO2/Cu(II) system.

Aiming at the coexistence of antibiotics and Cu(II) in livestock wastewater, a novelty strategy for the simultaneous removal of antibiotics and Cu ions by in-situ utilization of Cu(II) (i.e., CP/Cu(II) and CP/Cu(II)/ascorbic acid (AA) systems) was proposed. The removal rate of florfenicol (FF) in the CP/Cu(II)/AA system was 6.9 times higher than that of the CP/Cu(II) system. CP/Cu(II)/AA system was also effective in removing antibiotics from real livestock tailwater. Simultaneously, the removal of Cu ions in CP/Cu(II) and CP/Cu(II)/AA systems could reach 54.5 % and 15.7 %, respectively. The added AA could significantly enhance the antibiotics degradation but inhibit the Cu ions removal. HO^•, O₂^•-, Cu(III), and ^•C-R were detected in the CP/Cu(II)/AA system, in which HO^• was confirmed as the predominant contributor for FF degradation, and Cu(III) and ^•C-R also participated in FF elimination. The role of AA could accelerate HO^• production and Cu(I)/Cu(II)/Cu(III) cycle, and form ^•C-R. The degradation products and pathways of FF in the CP/Cu(II)/AA system were proposed and the toxicity of the degradation products was evaluated by the toxicity analysis software (T.E.S.T). The results of this work suggest that without introducing complex catalysts, the feasibility of in-situ utilization of Cu(II) inherently or artificially introduced in livestock wastewater activating CP for antibiotic degradation and Cu ions removal was verified.