Enhancing ¹O₂ pathway via ultrasound-coupled iron-carbon activated persulfate for improving sludge dehydration and reducing antibiotics mutagenicity

The massive use of antibiotics had induced gene mutations in microbial communities within waste sludge. It was necessary for environment treatment to co-disposal of sludge and antibiotic-containing residues. In this paper, ultrasonic (US) coupling of iron carbon (Fe-C) activated persulfate (PDS) demonstrated exceptional efficacy for sludge conditioning with the dehydration efficiency (88 %), the bound water content reduction (28 %) and the sludge reduction efficiency (25 %). The contents of characteristic organic matter were effectively degraded, such as humic acid (C1), tryptophan-protein-like (C2) and fulvic acid-like (C3) in sewage sludge. The free radical capture and EPR were utilized to determine reactive oxygen species (ROS) in the US/Fe-C/PDS system, where concentration of singlet oxygen (¹O₂) was as high as 1.2 × 10⁻¹⁰ mol/L to enhance the non-radical attack pathways. In addition, the degradation efficiency of model antibiotic - ciprofloxacin (CIP) was as high as 71 % in the sludge conditioning process. The CIP degradation pathways were speculated to attacked mainly by free radical (4C- quinolones) and ¹O₂ (11N- piperazine ring and 8C- quinolones) to degrade small molecules. TEST analytical results confirmed that ¹O₂-mediated degradation of CIP significantly reduced both ecotoxicological effects and mutagenic potential, as validated through comprehensive toxicity evaluation assays.