Aerobic Composting of Antibiotic-contaminated Manure: Degradation Processes and Their Effects on Greenhouse Gas Emissions

Introduction: The widespread use of antibiotics in livestock production results in significant excretion of unmetabolized residues in manure, posing risks such as the emergence of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), and elevated greenhouse gas (GHG) emissions. Composting has emerged as a promising strategy to mitigate these risks. Aims: This review formed a foundation for manure incubation regarding the fate and effects of three antibiotics – Tylosin, Enrofloxacin, and Oxytetracycline on manure GHG ammonia (NH3) emissions, and fertilizer quality. It synthesizes existing evidence on antibiotic degradation during composting, highlighting the influence of composting conditions, additives, and their effects on greenhouse gas emissions. Methods: A comprehensive literature search was done following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Systematic searches were performed in three databases: Web of Science, PubMed, and Scopus, for original articles using a combination of Query terms and an established inclusion and exclusion criteria. Results: The 66 studies that met the criteria were from 21 countries. Outcomes show that composting conditions (temperature, aeration, moisture), additive types (e.g., biochar, zeolite), and microbial inoculants play critical roles in antibiotic degradation and GHG emission dynamics. Thermophilic composting promotes degradation of labile antibiotics, while persistent compounds may require extended treatment. Overall, the review identified that physicochemical and microbial processes drive antibiotic degradation, suggesting that specific additives enhance these pathways, influencing GHG emissions. Conclusion: Composting is a viable strategy for managing antibiotic-laden manure and calls for further research into advanced treatments, bioaugmentation, and integration with other waste management technologies.