Overview of Desalination Technologies

摘要

The objective of this work is to present an overview of current and future technologies applied in therndesalination of brackish and seawater to produce fresh water for supplementing drinking water supplies. Thernthree basic categories of water desalination are membrane technologies, thermal technologies, and chemicalrnapproaches (Younos & Tulou, 2005). Membrane technologies are the most common technology of desalinationrnin the United States, while thermal technologies are commonly practiced in areas with abundant fossil fuelrnwith low cost such as Middle East (Watson et al., 2003). Chemical approaches include processes such as ionrnexchange, which is considered impractical for treating waters with high levels of dissolved solids. Chemicalrnapproaches have the potential of implementation in future and currently are mostly under research andrndevelopment for possible applications to desalination.rnMembrane treatment processes can be categorized to pressure-driven and electrical-driven technologies.rnPressure-driven membrane technologies include reverse osmosis, nano-filtration, ultrafiltration, andrnmicrofiltration (Duranceau, 2001). Electrical-driven membrane technologies that are effective with saltrnremoval include Electrodialysis, Electrodialysis Reversal and Electro-deionization (Brunner, 1990). Thermalrntechnologies are based on the concept of evaporation/distillation physical processes. These technologies arernapplied to desalination of seawater. Some common processes include multi-stage flush, vapor compressionrnand some variation of those technologies. The ion exchange technologies for water treatment are oftenrnused for water softening among other applications. The ion-exchange system can best be described as therninterchange of ions between a solid phase and a liquid phase surrounding the solid (Arden, 1968; Wachinski,rn1997; Sengupta, 1995). Several new technologies are being researched with potential for future applications torndesalination. New technologies include Membrane Distillation, Freeze Separation, Freezing with Hydrates,rnVacuum Distillation are also based on thermal technology (http://en.wikipedia.org/wiki/Desalination). All ofrnthese technologies are applied as a desalination method to increase the availability of potable water.