Sustainable on-farm strategy for the disposal of antibiotic fermentation residue: Co-benefits for resource recovery and resistance mitigation

Abstract

Antibiotic fermentation residue is a key issue for the sustainable operation of pharmaceutical companies, and its improper disposal may cause antibiotic resistance transfer in the environment. However, little is known about the resource recycling strategy of this pharmaceutical waste. Herein, we used hydrothermal spray-dried (HT+SD) and multi-plate dryer (MD) methods to produce bio-organic fertilizers and applied them to an internal recycling model of a field trial. The concentrations of antibiotics (penicillin, cephalosporin, and erythromycin) in the bio-fertilizer, wastewater, and exhaust gas were in the range of 0.002–0.68 mg/kg, ≤ 0.35 ng/mL, and 0.03–0.89 ng/mL, respectively. The organic matter and total nitrogen, phosphorus, and potassium contents were approximately 80% and 10%, respectively. The soil bacterial community was similar among the fertilizer treatments in the same crop cultivation. A total of 233 antibiotic resistance genes (ARGs) and 43 mobile genetic elements (MGEs) were detected, including seven Rank I ARGs and five Rank II ARGs. Random forest analysis showed that gene acc(3)-Via and plasmid trb-C were biomarkers, for which the resistance and the transfer mechanisms were antibiotic inactivation and conjugation, respectively. The results imply that AFR recycling disposal mode is a promising prospect for pharmaceutical waste management.