RO Processes Offer Water Supply Options

Abstract

wo rapidly growing reverse osmosis (RO) applications are seawater desalination and municipal wastewater reclamation. As water shortages increase, enhanced technology is improving the reliability of desalination processes and making produced water more affordable. RO Benefits RO technology continues to increase its market share in the desalination market because of the technology’s improved reliability and reduced energy requirements. Even in seawater applications, where high feed salinity requires high-pressure RO operation, energy requirements for RO processes are lower than the combined energy requirements of distillation processes (see figure below). In seawater desalination applications, high water permeability of today’s RO membranes, combined with increasingly higher salt rejection, enables users to optimize system operating parameters to minimize energy requirements. Additional energy reductions are possible with advanced energy recovery systems. However, further energy reductions will be minimal because of pressure limitations of the RO process and osmotic pressure of the concentrate stream. RO Options Forward osmosis (FO) is an emerging membrane desalination technology that does not have such pressure limitations. Although FO development is still in its early stages, the technology promises to significantly lower ener