Effects of Iron Additives on the Removal of Antibiotics and Antibiotic Resistance Genes in Anaerobic Fermentation of Food Waste

Anaerobic fermentation is an effective method for resource utilization of food waste. However, the presence of antibiotics and antibiotic resistance genes (ARGs) in food waste poses potential contamination risks to the products of anaerobic fermentation. Previous studies have reported the reduction effects of iron additives on antibiotics and antibiotic resistance genes. However, the effects of 500- and 50-nm zero-valent iron (ZVI) and magnetite on antibiotics and antibiotic resistance genes during anaerobic fermentation are still unknown. This study was based on a 7-day anaerobic fermentation experiment of food waste. It found that 500-nm magnetite effectively reduced the amount of tetracyclines at a rate of 81.04%, whereas 500-nm ZVI effectively reduced the amount of cefotaxime at a rate of 89.90%. Furthermore, both 500- and 50-nm ZVI reduced the types and abundance of heavy metal resistance and virulence genes. Also, 500-nm ZVI reduced the antibiotic resistance genes at a rate of 50%. Although 500-nm magnetite reduced the types of ARGs, it did not reduce their abundance. The findings of this study provided data support for addressing antibiotic contamination and antibiotic resistance issues during the anaerobic fermentation of food waste