Feasibility of sulfate-calcined eggshells for removing pathogenic bacteria and antibiotic resistance genes from landfill leachates

摘要

High abundance of human pathogen and antibiotic resistance genes (ARGs) in landfill leachate has become an emerging threat against human health. Therefore, sulfate- and calcination-modified eggshells as green agricultural bioresource were applied to test the feasibility of removing pathogenic bacteria and ARGs from leachate. The highest removal of Escherichia coli (£. coil) and gentamycin resistant gene (gmrA) from artificial contaminated landfill leachate was achieved by the application of eggshell with combined treatment of sulfate and calcination. The 16S and gmrA gene copies of E. coil declined significantly from 1.78E8 ± 8.7E6 and 4.12E8 ± 5.9E6 copies mL~(-1) to 1.32E7 ± 2.6E6 and 2.69E7±7.2E6 copies mL~(-1), respectively, within 24 h dynamic adsorption equilibrium process (p<0.05). Moreover, according to the Langmuir kinetic model, the greatest adsorption amount (1.56 x 10~9 CFU E. coil per gram of modified eggshells) could be obtained at neutral pH of 7.5. The optimal adsorption eggshells were then screened to the further application in three typical landfill leachates in Nanjing, eastern China. Significant decrease in species and abundance of pathogenic bacteria and ARGs (tet, sul, erm, qnr, and ampC) indicated its great efficiency to purify landfill leachates. This study demonstrated that sulfate-calcined eggshells can be an environmentally-friendly and highly efficient bioadsorbent to the management of reducing dissemination risk of pathogen and ARGs in landfill leachate.