The membrane distillation process is a membrane process that uses a porous hydrophobic membrane to effectively remove highly volatile components from a liquid mixture, and the permeation separation mechanism is as follows.
- The porous hydrophobic membrane is used to suppress the permeation of feed liquid (aqueous liquid) through pores, and allows the permeation of volatile components or water vapors.

The membrane distillation process can be mainly classified into DCMD (Direct Contact MD), AGDCMD (Air Gap DCMD), VMD (Vacuum MD), etc., and is selected and used according to the characteristics of feed mixture and separation process.

SepraTek™ membrane distillation membrane is a porous PP hollow fiber membrane and is available in two types of membranes: hollow fiber membrane with braided spacer and hollow fiber without spacer. The PP hollow fiber membrane without spacer is available in a variety of diameters, pore sizes, and porosities, depending on its application area, and the PP hollow fiber membrane with spacer is made by braiding it with a high-strength polymer fiber on its outer surface. The braid acts as a spacer between the hollow fibers, giving room to transfer a vacuum to each fiber and thereby providing a path of water vapor through each hollow fiber. Therefore, the membrane distillation module can effectively remove the water vapor that has penetrated through each hollow fiber membrane. Membrane distillation separation system is designed and engineered through systematic simulation and a series of groundworks to maximize the membrane performance as well as the economical value of the membrane process.

SepraTek offers a complete set of optimized membrane distillation systems as a turn-key base to meet the requirements for the economics and separation performance, and the specific requests of its customers.