Membrane operates without heating and therefore uses less energy than conventional thermal separation processes such as distillation, sublimation or crystallization. The separation process is purely physical and both fractions (permeate and retentate) can be used. Cold separation using membrane technology is widely used in the food technology, biotechnology and pharmaceutical industries. Furthermore, using membranes enables separations to take place that would be impossible using thermal separation methods.

Membrane operations:

Pressure driven operations-

• microfiltration
• ultrafiltration
• nanofiltration
• reverse osmosis

Concentration driven operations-

• dialysis
• pervaporation
• forward osmosis
• artificial lung
• gas separation

Operations in an electric potential gradient-

• electrodialysis
• membrane electrolysis e.g. chloralkali process
• electrodeionization
• electrofiltration
• fuel cell

Operations in a temperature gradient-

• membrane distillation