Like Reverse Osmosis, the mass transfer mechanism in Nanofiltration is diffusion. Though generally quite similar in terms of membrane chemistry, the Nanofiltration membrane allows the diffusion of certain ionic solutes (such as sodium and chloride), predominantly monovalent ions, as well as water. Larger ionic species, including divalent and multivalent ions, and more complex molecules are highly retained.

Since monovalent ions are diffusing through the Nanofiltration membrane along with the water, the osmotic pressure difference between the solutions on each side of the membrane is not as great and this typically results in somewhat lower operating pressure with Nanofiltration compared with Reverse Osmosis.

Some typical applications for Nanofiltration are:

  • Desalination of food, dairy and beverage products or byproducts
  • Partial Desalination of whey, UF permeate or retentate as required
  • Desalination of dyes and optical brighteners
  • Purification of spent clean-in-place (CIP) chemicals
  • Color reduction or manipulation of food products
  • Concentration of food, dairy and beverage products or byproducts
  • Fermentation byproduct concentration.

Dairy Industry

Segment Incoming Product Permeate Concentrate Results/Benefits
Cheese Salty Whey Salty wastewater Desalted concentrated whey Reduces transportation costs as well as recovery of lactose and whey protein solids.

 

Food & Beverage Industry

Segment Incoming Product Permeate Concentrate Results/Benefits
Baking Single strength later cook Water & salt minerals Gelatin Desalt gelatin for better whipping properties, and improve clear color.

 

Pharmaceutical Industry

Segment Incoming Product Permeate Concentrate Results/Benefits
Drug Industry Raw antibiotics Salty waste product Desalted, concentrated antibiotics Increases value of pharmaceutical product.

 

Industrial Industry

Segment Incoming Product Permeate Concentrate Results/Benefits
Textiles Slurry Mix Dyes Water, salts, BOD, COD and color Desalting dyes for a higher valued product.

Nanofiltration uses membranes to separate different fluids or ions.

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