Fresh, chilled, pasteurized dairy whey is either piped or delivered to the facility in specially designed tankers. After quality checks, the accepted whey is processed through ultra-filtration (UF) membranes which separate the fat & protein fractions of the whey from the remaining lactose, minerals and water.
The membranes are essentially very fine filters, and because the fat and protein molecules are larger than the other constituents, they are retained in the retentate stream, while the small molecules pass through the membrane to the Permeate stream.
As more and more of the permeate is removed, the protein content of the retentate is increased allowing the production of WPC with differing compositions. Once the desired protein content has been achieved the retentate is then evaporated under vacuum, and spray dried to form a protein powder that can be used for many food and nutritional applications.
The permeate stream is passed through Reverse Osmosis (RO) membranes, which are finer than the UF membranes, therefore retaining the lactose and some of the larger mineral molecules, and allowing the water to pass through. The water is then further filtered using even finer membranes and is used as processing and cleaning water for the facility. In fact around 75% of the incoming whey volume is converted to clean water. As this is in excess of the factory requirements, the plant is actually a net producer of water.
The concentrated permeate stream containing the lactose is then evaporated under vacuum to a stream of very high solids. This stream is then crystallized by pumping the product into crystallization vessels, which lower the temperature slowly, causing the solution to become saturated and form lactose crystals. Over time, these crystals grow large enough so that they can be washed to remove surface impurities and dried into lactose monohydrate.