Design Advantages for SWRO Using Advanced Membrane Technology

Abstract

Seawater desalination technology has been growing rapidly during the past five years, partly because significantly improved membranes that can lower permeate salinity and operating pressure are available. Optimum design with recently developed low-pressure seawater elements should be carefully considered. This article analyzes such membranes. For lower feed temperatures and salinities, low-energy seawater elements can provide sufficiently low permeate salinity, generally less than 500 mg/L. Alternatively, designers can use hybrid designs, in which high-rejection, high-energy consumption elements are used in the front of the vessel and low-energy elements are used in the back of the vessel. These products can yield as much as 1 kW?h/kgal of energy savings. In addition, lower permeable lead elements have lower flux, resulting in a more balanced element flux distribution. Alternatively, these new membranes can be used in configurations having as much as 440 ft² of membrane area. Greater area can result in about 0.1/gpd in capital costs savings. However, detailed analysis is needed to select the optimum element and configuration.