Membrane based separation processes have been one of the most promising techniques in water and wastewater treatment. However, membrane fouling due to the accumulation of contaminants on the membrane surface or within its pores has remained a big challenge toward the wide application of this technology. Fouling results in a decreased membrane performance, costly cleaning procedures, and frequent membrane replacements. As such, the development of membranes with enhanced antifouling and rejection performance is of crucial importance.In this work, a facile novel membrane modification method was developed to promote membrane applicability to synthetic and field produced water (PW) treatment. Commercially available ceramic membranes with different pore sizes were decorated with in situ generated iron oxide nanoparticles (NPs). Characterization showed successful incorporation of uniformly distributed ?-Fe_2 O_3 NPs of 4 – 15 nm on the membrane surface and within the active layer. Relative to as-received (AR) membranes, modified (MM) membranes exhibited higher intrinsic hydraulic resistance, lower surface roughness, and enhanced surface and pore hydrophilicity.A novel dimensionless number calculated based on permeate flux and contaminant rejection captured higher membrane efficiency (up to 3 times) with slight/no decrease in permeate flux for membranes having low NPs content. Higher NPs loading, however, decreased the membrane performance owing to pore plugging and organic adsorption. In addition, MM membranes exhibited enhanced antifouling characteristics in terms of flux decline (reduced 4 – 60 %) and fouling reversibility (increased 4 – 30 %). Modification impacted loose membranes to a greater extent, where with optimized NPs loading, larger pore size MM membranes rejected organics to the same extent as tight membranes while providing higher permeate flux.A combined stream of organic (humic acid, HA) – inorganic (silica, Si) colloidal contaminants contributed to more severe combined fouling for all membranes, while organic rejection was not considerably affected by Si. Intermolecular adhesion energies between the contaminants and the membrane surface successfully predicted the enhanced antifouling characteristics. The accuracy of combined fouling extent prediction, however, was not adequate probably since fouling mechanisms other than adsorption, including pore restriction, are not accounted for in the model.Overall, a facile, inexpensive, and efficient membrane modification method was developed. The modified membranes offered significantly enhanced performance and antifouling characteristics toward synthetic and field PW.