Antibiotic class-dependent degradation mechanisms and resistance gene elimination by dielectric barrier discharge cold plasma technology for wastewater treatment.

Antibiotic residues persisting in aquatic systems at sub-inhibitory concentrations actively drive the spread of antibiotic resistance genes (ARGs), contributing to 1.27 million deaths annually. Conventional treatment methods achieve only 6-37% antibiotic removal and fail to eliminate resistance determinants, establishing the need for advanced alternatives. Dielectric barrier discharge (DBD) cold plasma generates reactive oxygen and nitrogen species (RONS) at atmospheric pressure, enabling the degradation of parent antibiotics and the reduction of ARG abundance in a single treatment. Each antibiotic class degrades through a structurally distinct mechanism: β-lactams undergo rapid ring opening, fluoroquinolones require synergistic oxidative-reductive defluorination, tetracyclines follow stepwise hydroxylation and deamination, and sulfonamides and macrolides primarily undergo S-N and lactone bond cleavage. Removal efficiencies exceeding 90% have been reported for fluoroquinolones, tetracyclines and sulfonamides within 10-60 min under optimized conditions in deionized water; however, these efficiencies may be substantially lower in complex real wastewater matrices. For ARG elimination, DBD plasma achieves up to 15-log reductions in the qPCR-measured abundance of blaTEM-1, aac(3)-II, tetC, tetW, and intI-1 through direct DNA strand breakage and antibiotic-resistant bacteria (ARB) inactivation, though intracellular ARGs (i-ARGs) require 2.5-fold higher plasma energy doses than their extracellular counterparts. This review introduces a class-dependent plasma antibiotic reactivity mapping framework, critically evaluates reactor configurations and process optimization, and highlights the urgent need for studies at environmentally realistic concentrations to bridge the gap between laboratory performance and real-world application.