integrated , sequential stages of nanofiltration , forward osmosis , and reverse osmosis and related membranes provide an integrated osmosis structure , systems and methods . by optimally placing and using the desired characteristics of each membrane , performance and cost effectiveness not attainable individually is obtained . integrated osmosis systems provide high diffusive and osmotic permeability , high rejection , low power consumption , high mass transfer , and favorable peclet number , by manipulating convection , advection and diffusion , low concentration polarization gradients , low reverse salt flux and effective restoration of performance after cleaning fouled membranes . benefits include increased permeate recovery and decreased waste concentrate volume from reverse osmosis processes or other elevated osmotic pressure solutions . integrated osmosis first employs nanofiltration for selective harvesting of solutes , proffering a reduced osmotic pressure permeate . forward osmosis dewaters the lowered osmotic pressure permeate generating a dilute draw solution which serves as feed to a reverse osmosis process . reverse osmosis permeate provides freshwater and concentrate provides draw solution for the forward osmosis process .