The invention is directed to a nanosieve composite membrane, a method for preparing a nanosieve composite membrane, a roll-to-roll apparatus for carrying out the method, and a method for separating a feed flow with particulate matter. The nanosieve composite of the invention comprises an inorganic nanosieve layer supported on a porous polymer membrane substrate and a metallic adhesion layer or underlayer between the inorganic nanosieve layer and the polymer substrate, wherein said polymer membrane comprises an inorganic coating such that the polymeric support is sandwiched between the inorganic coating and the inorganic sieve layer, and wherein said inorganic nanosieve layer has an average pore diameter as determined by scanning electron microscopy of 200 nm or less.