Cheese whey is a yellowish liquid remaining after milk coagulates during cheese production. It is a by-product of the manufacture of cheese and has several commercial uses.

Cheese whey is produced in huge amounts and is a significant environmental problem due to the high levels of organic matter content (Kosikowski, 1979). Cheese whey represents a biochemical oxygen demand (BOD) of 30-50 g/l and a chemical oxygen demand (COD) of 60-80 g/l lactose is largely responsible for the high BOD and COD, since protein recovery reduces only about 12% of the whey COD (Domingues et al., 1999a; Siso, 1996; Siso et al., 1996).