The Unexpected Performance of Highly Permeable SWRO Membranes at High Temperatures

Abstract

Development of new seawater reverse osmosis (SWRO) elements has recently focused on maximizing membrane area and membrane permeability. Such developments led to a new generation of SWRO elements with significantly increased permeate flows and lower pressures. When tested at the same pressures and temperatures, SWRO membranes produce nearly twice as much permeate today as they produced 10 years ago. Using highly permeable membranes in SWRO plants leads to less energy consumption and lower operating costs. This article reviews the theory behind the competing influences of membrane permeability and osmotic pressure on overall feed pressure and demonstrates how advancements in SWRO permeability have increased the influence of osmotic pressure on membrane performance. Membrane performance tests identify temperature ranges and membrane permeabilities with the least and greatest influence on SWRO system operating costs.