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Distribution and removal of antibiotic resistance genes in a landfill leachate treatment process

ABSTRACT Domestic waste landfills have been regarded as the main source of antibiotic resistance genes (ARGs) which are considered to be emerging environmental contaminants. Fluorescent quantitative PCR detection was used to determine the occurrence and abundance of ARGs in a landfill leachate treatment system. Fourteen ARGs were detected initially in the leachate influents. The most abundant ARGs were IntI1, followed by sulI, sulII, sulIII, tetC and tetW. The abundance of ARGs increased in the biological treatment unit and then decreased in the effluent of ultrafiltration membrane treatment. The absolute abundance of ARGs in effluent was 1.05–1.94 orders of magnitude lower than that in influent. There was a very significant strong correlation between various ARGs and heavy metals, especially Zn, Pb, Cu, Cd and As, indicating that there may be obvious co-selection between heavy metals and ARGs. Although the leachate treatment process could effectively reduce the abundance of ARGs, its effect on reducing the number of species of ARGs was relatively limited, which may have potential environmental health risks to the urban sewage plant receiving leachate effluent and the final receiving water body.