Whey is a highly polluting by-product of cheese and casein powder manufacture with worldwide production of whey estimated at around 190 × 106 ton/year and growing. Historically whey was considered a burdensome, environmentally damaging by-product. In the last decades however, much research has gone into finding viable alternatives for whey rather than just disposing of it. Multiple biotechnological avenues have been explored and in some cases exploited to turn this waste product into a valuable commodity. Avenues explored include traditional uses of whey as both an animal and human food to the more advanced uses such as the use of whey protein as health promoters and the potential of whey to be used as a feed stock to manufacture a whole range of useful substances e.g. ethanol.