Hybrid configuration of membrane distillation: Vacuum multi-effect membrane distillation

Vacuum membrane distillation (VMD) has been gaining attention as a cost-competitive membrane separation technology due to its advantages, which include low conductive heat loss and reduced mass transfer resistance. Vacuum multi-effect membrane distillation (V-MEMD) is an advanced hybrid configuration that achieves additional system enhancements, such as heat recovery, by operating multiple stages within a VMD system. These enhancements to the VMD configuration overcome many of the limitations faced by other membrane distillation (MD) configurations. The Memsys V-MEMD configuration is an example of a highly efficient commercialized system that combines both vacuum and multi-effect distillation to achieve enhancements in both mass transfer and heat recovery. In this chapter, an assessment of system availability and the application of hybrid MD configurations (particularly V-MEMD) is presented. In particular, the evolution of membrane distillation configurations is discussed up to the point where V-MEMD was introduced and commercialized as an advanced hybrid configuration. In addition, we present theoretical and technical discussion of the working principle and performance indicators of the commercial Memsys V-MEMD module. A number of pilot and full-scale applications of V-MEMD systems for different industrial applications, mainly by Memsys and CSRE, are reviewed with a focus on system performance.