A novel class of microfiltration membrane, based on a two-layered nanoscale polyacrylonitrile (PAN)/microscale polyethylene terephthalate (PET) fibrous scaffold containing infused ultra-fine functional cellulose nanofibers (diameter about 5 nm), was demonstrated. These membranes can simultaneously remove bacteria, viruses and/or toxic heavy metal ions. To be specific, the demonstrated membrane was capable of completely removing Escherichia coli (by size extrusion), reaching a LRV of 4 for MS2 virus removal and having the adsorption capability of 100 mg Cr (VI) or 260 mg Pb (II) per gram of cellulose nanofiber, while maintaining a high permeation rate (1300 L/m(2)h/psi). The development of these membranes was based on the creation of a web-like structure with very high charge density and large surface area per unit volume for adsorption of contaminant molecules. (C) 2013 Elsevier B.V. All rights reserved.