Performance of Ultraviolet (UV), O₃, and Their Combined Processes for the Antibiotic Resistance Abatement from Swine Wastewater

Swine wastewater is considered one of the major pollution sources of antibiotic resistance to the environment. In this study, the elimination of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) through various treatment processes, including ultraviolet (UV), O-3, and their combined processes, in biotreated swine wastewater was investigated. The combination modes of UV and O-3 were optimized, and the mechanisms underlying ARG removal were explored by assessing the destruction of intracellular ARGs (i-ARGs) and extracellular ARGs (e-ARGs). The results indicated that the synchronous exposure to UV and O-3 (i.e., the UV/O-3 process) was the optimal combination mode, which could accelerate the removal of ARB and enhance the elimination of target ARGs (i.e., tetA, ermA, and intI1) by a maximum of 0.9-1.3 and 0.4-0.8 logs, respectively, when compared to the single ozonation and UV treatments. The concurrent destruction of i-ARGs and e-ARGs implied that the advanced oxidation properties of the UV/O-3 process compensated for the limitations of ozonation in a complex wastewater matrix and capitalized on the strengths of both UV and ozonation in damaging ARGs. Overall, UV/O-3 is a feasible polishing process, subsequent to biological treatment, for effectively abating antibiotic resistance from swine wastewater.