(222c) Membrane Distillation Processes for Water Desalination

Membrane distillation for desalination employs heated brine in contact with a porous hydrophobic membrane to generate water vapor which is recovered in a variety of ways on the other side of the membrane. Direct contact membrane distillation (DCMD) employs colder distilled water on the other side to condense the water vapor. Air gap membrane distillation (AGMD) devices utilize a cold surface to condense the water vapor and generate the distillate. This presentation will focus primarily on hollow fiber membrane-based devices for DCMD as well as AGMD. For AGMD the colder condensation surface is provided by a solid nonporous hollow fiber. Novel two hollow fiber-based AGMD devices will be illustrated and the relation of AGMD to DCMD will be explored. For DCMD an overview of the device performance, resistance to scaling, concentration cascades and energy requirements will be provided for a variety of brines. Results of studies with brine and produced water will be provided for feeds at temperatures in the range of 100 C-130 C as well. The relative performances of a variety of polymeric and ceramic membranes will be discussed.