What is a membrane?
Membrane processing is a technique that permits concentration and separation without the use of heat. Particles are separated on thebasis of their molecular size and shape with the use of pressure and specially designed semi-permeable membranes.
The material of which a membrane is usually built of:
1. Cellulose acetate 2.Aromatic polyamide 3. Thin-film composites 4. Other types of polymers
The membrane structure:
1. Cellulose acetate membrane Approximately 4mm thick and asymmetric in design
The thin layer is thesalt rejecting surface, while the thick, porous layer acts as a support layer only. Have limited chemical and physical stability.
2. polyamide membrane Outer diameter of 85 microns and an internaldiameter of approximately 42 microns Better stability to chemical and biological attack compared to cellulose acetate, Degraded by chlorine
Fibers are asymmetric in construction.
3. Thin filmcomposite membrane The membrane composite consists of three layers - a polyester support web, a microporous polysulphone inter-layer,And a ultra-thin barrier layer These membranes offer excellentchemical and biological stability. 4. Other types of materials: There are other membrane structures in the market depending on the uses and the application of the membrane.
There are 4 types ofmembranes differing by the size of the pores
1. Micro filtration: The membrane allow particles in the range of 0.2 to 2 micrometers to pass through Operating pressure is usually 10-100 psig.Applications: •Cranberry juice clarification •Wine filtration •Industrial Waste Water Treatment- Removes suspended solids and insoluble metal hydroxide solids from wastewater. •Fermentation broth clarification2. Ultra Filtration membranes: Operating pressure of 1-150 psig. Temperatures of 50-60°C
Applications: •Potable Water- removal of bacteria, and viruses from drinking water. •Oily Wastewater...