In this work, two categories of thin film nanocomposite (TFN) membranes have been synthesized via in-situ and ex-situ aspects for grafting biocide Fe-0 nanoparticles on the membrane surface. A comparison between ex-situ and in-situ routes also was comprehensively studied. The membrane morphology and surface properties were also studied using contact angle measurements, FT-IR, AFM and SEM, along with desalination performance in terms of water flux and salt rejection. The permeate flux of NaCl solution was 12.93 L/m(2) h for the neat TFC while it was 13.9 and 13.6 L/m(2) h for the TFN obtained in in-situ and ex-situ aspects, respectively. The river water flux recovery of TFN membranes was about 89% in the long term filtration experiments, while it was 71.29% for the neat TFC membrane. To study the anti-bacterial properties of doped membrane, a new method for evaluation the killing effects of iron nanoparticles on bacteria was differently suggested. The results showed good anti-adhesion effects of TFN membrane containing zero-valent Fe nanoparticles on river or seawater natural bacteria. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.