Distribution, removal and potential factors affecting antibiotics occurrence in leachate from municipal solid waste...

Leachate from municipal solid waste (MSW) incineration harbors a plethora of contaminants, including antibiotics and antibiotic resistance genes (ARGs). However, the understanding of such leachate is markedly scant in comparison to that of landfill leachate. In this study, the distribution and removal of 8 sulfonamides (SAs), 4 quinolones (FQs), and 4 macrolides (MLs) antibiotics in leachate from 14 MSW incineration plants in representative cities across different regions of China were investigated. In addition, potential factors affecting the contamination levels of antibiotics and ARGs in fresh leachate were evaluated. The results showed that the total concentration of target antibiotics in fresh leachate ranged from 4406.1 to 14,930.6 ng/L. Notably, the antibiotic distribution in leachate exhibited regional disparities, influenced by economic status, climatic conditions, and waste separation policies. The absolute abundance of total ARGs ranged from 1.3 × 10⁷-4.0 × 10⁸ copies/mL, with the mobile genetic elements intl1 facilitates the dissemination of qnrS, sul1 and sul2. No distinct regional distribution of the ARGs was observed among different cities. Antibiotic and ARGs distributions were significantly correlated with total organic carbon, pH, ammonia nitrogen, heavy metals, and microbial communities. Moreover, SAs were identified as contributors to the proliferation and spread of corresponding ARGs. Fourteen typical "anaerobic-anoxic/aerobic-anoxic/aerobic-ultrafiltration-nanofiltration " treatment processes removed the target antibiotics effectively (76.1 %-97.0 %). Biodegradation was considered to be the dominant antibiotic removal pathway, removing 62.0 %-90.9 % of antibiotics, while sludge adsorption removed only 1.0 %-11.7 %. This research furnishes valuable insights into the fate of antibiotics in MSW incineration leachate.