Polymer membranes produced by electrospinning have great potentials in the separation of oil/water emulsion under gravity. Removal of oils from the emulsion has been realized by superhydrophobic membranes due to selective penetration of oils. In this study, we demonstrate that blend electrospinning of polylactide (PLA) with a biodegradable and biocompatible polyester (P34HB) produces membranes with complete water permeability. In contrast, PLA membranes are highly hydrophobic and cannot be penetrated by water. The water permeability is correlated with more hydrophilicity of P34HB than PLA and especially with structural porosity of the membranes. The water-permeable membranes exhibit superior removal of water from the emulsion under gravity, exactly opposite to the situation encountered by superhydrophobic membranes. (C) 2015 Elsevier B.V. All rights reserved.