A magnetic nanocomposite (NC), Fe3O4@PPy-MAA, was synthesized via in situ oxidative polymerization of the pyrrole monomer in a thioglycolic (mercaptoacetic) acid solution (as a dopant), in the presence of iron oxide (Fe3O4). The newly developed NC was characterized for physical and chemical properties. The performance of the NC for silver ion (Ag+) adsorption was carried out through batch studies as a function of pH, adsorbent dose, temperature and initial Ag+ concentration. The maximum adsorption capacity of Ag+ was determined to be 806.45 mg/g at 25 °C using Langmuir adsorption isotherm at a solution pH of 5.6 and adsorbent dose of 0.5 g/L. The adsorption kinetics studies indicated that the Ag+ adsorption onto the Fe3O4@PPy-MAA NC surface was rapid within the initial 40 min and was well described by the pseudo-second-order kinetics equation. Also, the present study emphasized the re-usability of silver-adsorbed waste material for the disinfection of microorganisms, which was demonstrated through the excellent antimicrobial activity of the NC against Escherichia coli and Salmonella in both synthetic and natural water samples. Therefore, the as-prepared Fe3O4@PPy-MAA NC has an excellent ability to successfully remove Ag+ ions from aqueous solutions and subsequently, the Ag-loaded waste material could be used as a potential candidate disinfectant.Preliminary continuous fixed-bed column studies for E. coli inactivation echoed the findings in batch studies.