Towards a simultaneous combination of ozonation and biodegradation for enhancing tetracycline decomposition and toxicity elimination

In this study, a new intimately coupling technology of advanced oxidation and biodegradation was proposed, called simultaneous combination of ozonation and biodegradation (SCOB), which uses ozonation in place of traditional photocatalysis. SCOB was evaluated for its ability to degrade and detoxify tetracycline hydrochloride (TCH). Biodegradation alone only resulted in negligible TCH removal, while ozone alone caused less effective performance, with TCH degradation rate constants of 29–171% lower than those of SCOB. The optimal ozone dose was 2.0 mg-O₃/(L·h), and it contributed to remove 97% of the TCH within 2 h under SCOB operation. The SCOB effluent was not toxic to S. aureus after 8 h of exposure. During six SCOB operation cycles, the biomass in the biofilm remained stable, and cell structure was relatively intact. SCOB significantly improved TCH degradation and reduced toxicity of the effluent.