Changes in Nitrogen and Humus During Aerobic Composting Under Antibiotic Composite Pollution

Antibiotic residues have significantly effects on aerobic composting process. This study was targeted at antibiotic composite pollutants (e.g., sulfanilamides, tetracyclines, and quinolones) and probed into the effects of pollution levels on aerobic composting. With higher initial antibiotic concentrations, the NH4+ –N and NO3− –N concentrations at the end of composting were higher, but TN content decreased, which may be due to the inhibition effects of antibiotics on nitrogen-fixing bacteria and thus were unfavorable for nitrogen accumulation. Antibiotic pollution obviously delayed composting maturity, and the antibiotics at initial concentration above 306.12 mg/kg were significantly toxic to seeds. Analysis of structural changes in dissolved organic matter (DOM) showed the humification after treatments CK and AT100 mainly occurred at the high-temperature stage (day 2–14) and later lower-temperature maturity stage (day 21–36). Humification after treatment AT300 mainly happened at the high-temperature stage (day 2–14), and that in AT600 mainly occurred at the early temperature rise and high-temperature stage (day 2–7). This study comprehensively evaluated the effect of antibiotic composite pollution on the maturity of aerobic compost, and provided a theoretical basis for the treatment of antibiotic composite pollution materials in practical production.