Fe-functionalized sewage sludge biochar coupled with H2O2 for efficient antibiotic removal and potential pathogen reduction in wastewater

: The overuse and misuse of antibiotics have led to their increasing release into aquatic ecosystems, promoting the selection and spread of antibiotic-resistant bacteria and potentially pathogenic microorganisms. In this study, biochars derived from sewage sludge and spent coffee grounds were produced, functionalized with iron, and coupled with H2O2 for the treatment of real municipal wastewater containing levofloxacin, doxycycline, and ampicillin. Response Surface Methodology identified sewage sludge biochar produced at 650 °C as the most effective material, and the optimized heterogeneous oxidation conditions were 30 g L-1 Fe-SSBC650 and 120 mg L-1 H2O2. Under these conditions, the Fe-SSBC650/H2O2 system achieved near-complete removal of the selected parent antibiotics after 60 min, with Ct/C0 decreasing to 0.03 ± 0.02, corresponding to approximately 97% removal. In the validation experiment, antibiotic concentrations followed the trend UW > WP > FeBC > BP, with the BP treatment achieving >99% abatement of the target compounds. The optimized treatment also strongly affected bacterial community composition and significantly reduced the relative abundance of potentially pathogenic bacteria compared with untreated wastewater and control treatments. Conversely, antibiotic resistance genes and class 1 integrons showed inconsistent responses, indicating that parent-antibiotic removal did not necessarily correspond to a parallel reduction in antibiotic resistance markers. These findings indicate that Fe-functionalized sewage-sludge-derived biochar coupled with H2O2 is a promising preliminary platform for parent-antibiotic removal and bacterial community modulation in real wastewater, while further optimization is required to improve catalyst management, assess transformation products, and address antibiotic resistance mitigation.