Chapter 17 - Forward Osmosis

Abstract

Forward osmosis (FO) is a widely used separation process utilizing the osmotic pressure difference induced by the solute concentration difference between the feed and draw solutions. This chapter discusses solute and water transport through an asymmetric FO membrane, taking into account the mass transfer resistance of all transport layers, namely the membrane active and support layers, as well as the external fluid boundary layers. The resistance-in-series layered model is applied to it (Nagy, 2014). It also discusses the effect of the membrane structural parameter on the transport rates, the interface concentrations, and the overall mass transfer coefficient. In the second part of this study the effect of the cake layer is briefly discussed. The solute transport model of the cake layer (Tow and Lienhard, 2016) is integrated into the resistance-in-series model, and this new unique model is applied to predict the effect of the fouling layer on the water and solute transport process. This unique model is shown how strongly can reduce the cake layer the water flux.