Synergistic effect on sludge disintegration and antibiotic resistance genes removal during sludge treatment by combined plasma-calcium peroxide

Excess sludge generated during wastewater treatment serves as a major reservoir of antibiotic resistance genes (ARGs), posing environmental and public health risks. In this study, a combined plasma-calcium peroxide (Plasma-CaO₂) treatment was proposed to simultaneously enhance sludge disintegration and ARGs removal. Compared with solo treatment, Plasma-CaO₂ significantly improved sludge disintegration, as evidenced by a higher disintegration rate (9.7%), more markedly increased lactate dehydrogenase (LDH) release (656.9%), and more fragmented flocs. The treatment also promoted the release of intracellular and floc-embedded organics, leading to substantial increases in soluble and tightly bound extracellular polymeric substances (S-EPS and TB-EPS), with S-EPS responding first during the reaction. Alongside with the sludge disintegration, an evident synergistic effect on ARGs removal was observed, particularly for tetW with a 2.4-log reduction. This decline might be attributed to the release of ARGs into liquid, followed by oxidative degradation via ROS. Significant negative correlations between ARGs and LDH, S-EPS further confirmed the role of sludge disintegration in facilitating ARGs removal. Co-occurrence analysis indicated family Burkholderiaceae as a potential host for bla_TEM-1, tetC and aac(3)-Ⅱ. ¹O₂ was proven as the most critical ROS driving sludge disintegration and ARGs removal. Summarily, the combined Plasma-CaO₂ system offers a promising strategy in sludge pre-treatment.