Performance of commercial seawater membranes

This paper evaluates the membrane parameters which should be considered in order to project the performance of reverse osmosis seawater systems. In addition to the manufacturer's nominal membrane data and well-known dependence of permeate flux on net driving pressure and feedwater temperature, these parameters should also include the effects of feed salinity on water flux and feed temperature on salt transport. In RO systems equipped with spiral-wound membrane elements the feed pressure, one of the most important system operating parameters, has been customarily limited to 1000 psi (70 bars). An evaluation of the technical feasibility of the customary pressure limit for spiral-wound membrane systems at representative sites is contained in this paper. Improved salt rejection of the currently available seawater membrane elements enables operation at high recovery rates. This paper also evaluates and compares the relative advantages of single and two concentrate-staged membrane element array configurations for high recovery seawater systems.