Coupling Aerobic-Anaerobic Technology to Reduce Microbial Resistance and Maintain Efficient Degradation in Sewage Sludge Treatment

Sewage sludge treatment faces dual challenges of efficiency and safety, and conventional approaches rarely to address both simultaneously. Three aerobic and anaerobic coupling technologies—Anaerobic-Oxygen (AO), Oxygen-Short-term Anaerobic (OSA), and Oxygen-Long-term Anaerobic (OLA)—were evaluated through physicochemical, microbiological, functional enzymological and microbial resistance analyses. The results indicated that the OSA and OLA technologies displayed physicochemical properties comparable to aerobic composting (CK group), while the AO group lacked a crucial thermophilic stage. In these coupling systems, Streptomyces , Bacillus , Thermostaphylospora , and Paenibacillus were identified as the primary functional genera, contributing to substrate degradation and resistance gene removal. The OLA technology, integrating a 14-day anaerobic phase, maintained lignocellulose and nitrogen compounds degradation efficiency comparable to conventional composting, and reactivated endoglucanase and protease activities during the later stages. More importantly, this technology demonstrated superior performance in eliminating resistance genes and suppressing their rebound. The removal rate of antibiotic resistance genes in the OLA group (81.69%) was approximately twice that of the CK and AO groups, while the removal rates of heavy metal resistance genes (90.32%) and mobile genetic elements (96.47%) also outperformed those in all other groups. The enhanced elimination likely resulted from temperature-driven and aerobic/anaerobic transitions-induced bacterial community succession that disrupted resistance gene carriers. These findings reveal that the coupling sequence and anaerobic duration crucially influenced hybrid treatment performance. The optimal OLA technology provides an effective solution to the efficiency and safety issues in sewage sludge treatment and advances mechanistic understanding of microbial resistance variation in complicated aerobic-anaerobic systems, which broadens organic waste management strategies.