Membrane Distillation Process

Membrane distillation (MD) is a thermally driven separation process in which separation is driven by phase change. A hydrophobic membrane presents a barrier for the liquid phase, allowing the vapour phase (e.g. water vapour) to pass through the membrane's pores.

Membrane Distillation (MD) is a relatively new and promising separation technology that is an alternative to more energy intensive methods such as reverse osmosis or distillation. MD is a thermally driven process where only vapor molecules transfer through a hydrophobic (water repellent), microporous membrane.

A typical membrane distillation technique features a membrane filter sandwiched between cold solution on one side and hot solution on the other side. The driving force of the MD process is the partial vapor pressure difference induced by the temperature difference across the hydrophobic membrane. The vapor then condenses on the cold side to produce the distillate

MEMBRANE DISTILLATION APPLICATIONS

MD membranes are suited for applications where water is the major component, including desalination, purification, and treatment of process water or for temperature-sensitive industrial products such as the following:

1. Concentration of aqueous solutions in food industries
2. Concentration of a range of dairy streams, such as whole milk, skim milk and whey
3. Concentrating acid solutions or regenerating acids or separating acids
4. Removal of volatile organics

ADVANTAGES OF MEMBRANE DISTILLATION

Compared to conventional membrane processes, MD has the following benefits: 

1. Low temperature (max 88°C/190°F) compared to conventional distillation
2. Low hydraulic pressure (max 100 psi) compared to pressure driven membrane separations
3. Less expensive membrane compared to reverse osmosis
4. Ability to use waste heat or solar energy