Introduction. The purpose of this project was to convert a dairy waste into value-added products, whey protein concentrate and fuel ethanol. Evangelista applied three technologies---ultrafiltration, reverse osmosis, and immobilized-cell fermentation---to do the transformation.
Ultrafiltration. Ultrafiltration allowed the small water, salts, and lactose molecules to pass through or permeate its membrane, and retained or concentrated the larger molecules of protein behind the membrane. The retained protein was whey protein concentrate, one of today’s “superfoods.” The ultrafiltration permeate went to reverse osmosis for further processing.
Reverse Osmosis. Reverse osmosis, a "tighter" semi-permeable membrane, allowed the very small water molecules to pass through or permeate, and retains or concentrates the larger salts and lactose behind the membrane. Reverse osmosis made a pure water permeate that could be discharged directly to the environment. The retentate or concentrate, called whey permeate concentrate, was sent to immobilized yeast fermentation.
Immobilized Yeast Fementation. Yeast were fixed inside a media and placed into a bioreactor to metamorphose lactose into ethanol. The immobilized yeast bioreactors had the distinct advantages of rapidly converting whey permeate concentrate into ethanol.
More Information. Conversion of Membrane Processed Whey into Protein and Ethanol using Immobilized Yeast Fermentation. R. Evangelista, Prepared for the U.S. Department of Energy.
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