Chapter 15 - Membrane distillation technology applied in water resources

Abstract

Membrane technology for water purification has made tremendous progress during the last decade. Membrane distillation (MD) is a nonisothermal membrane separation process, a thermally driven vapor transport through a porous hydrophobic membrane with a vapor pressure difference between the two sides of the membrane pores as the driving force. MD has a high rejection factor, an extremely high concentration rate, a most straightforward configuration, and is suitable for desalination and removal of volatile compounds from aqueous solution. Furthermore, MD is beneficial for chemical recovery, such as ammonia from dye manufacturing. The application of MD in various configurations is a topic of interest among researchers and is examined by the industry. However, a clear understanding of MD's mechanism and the process is needed to distinguish between MD and osmotic distillation (OD) or pervaporation (PV). Membrane properties and characterization are essential for MD's operations. Despite MD's advantages, this system has some disadvantages that need to be improved. Furthermore, MD's prospects and future directions need to be discussed.