Influence of different Ag/ZnO heterostructures on the removal efficiency of multidrug-resistant Enterococcus faecium harboring multiple resistance genes from tap water

The adsorption efficiency of different Ag/ZnO heterostructures was investigated for the removal of multidrug-resistant Enterococcus faecium (MDR_EF) harboring multiple resistance genes from tap-water. The concentration of the precursors influences the microstructures of the adsorbents; however, it did not significantly affect the adsorption efficiency. The maximum adsorption capacity, q(e), (34.11 CFU/g), was obtained for Ag1Zn3.5. The kinetic studies revealed that Ag1Zn1 and Ag1Zn2 adsorbents agreed to the pseudo-first-order kinetic equation and adsorbents Ag2Zn1, Ag3.5Zn1 and Ag1Zn3.5 agreed to the pseudo-second-order kinetic equation. Initial tap-water pH range was beneficial for the adsorption and the pH of the treated tap-water was within the WHO tap water recommendation (6.5-8.5), whereas the effect of ionic strength, anionic and cationic interference was insignificant in the adsorption of MDR_EF onto the different heterostructure. Interestingly, the MDR_EF could retain its cell membrane integrity and resistance genes, suggesting that surface adsorption was the primary mechanism for the removal.