The manufacture of ethanol from whey
The disposal of whey is a worldwide problem. Large quantities of whey are produced as a by-product during the manufacture of cheese and casein, and this must be disposed of or processed in an environmentally acceptable way. Since most of the components are of small molecular weight and soluble, they can quickly deplete oxygen levels in natural water systems: the COD (Chemical Oxygen Demand) of raw whey is about 60 kg m-3.
The key to the utilisation of this resource has been changing the perception of whey from a 'waste material' to an 'opportunity' for further processing. The success of the NZ Whey Corporation in turning whey products into a multi million dollar profit centre for the New Zealand dairy industry is evidence of the success of the change in perception. Deproteinated whey, or serum derived from the Whey Corporation plant, was seen as an opportunity for ethanol production. Sweet wheys, such as those derived from the production of cheese, were already being used to make lactose powders (see article). Acid wheys from the production of lactic and sulphuric casein are not suitable for this (as they contain high levels of sulphate ions and lactose acid), but it was seen that they could be used to ferment the lactose to ethanol.