Large amounts of whey produced is posing a serious problem all over the world for its proper utilization. Only a few countries have succeeded in utilizing their total whey production [147]. Whey is rich in lactose, a dimer of glucose and galactose unit, and can be fermented only by a selected number of yeasts. Because glucose and galactose are readily fermentable sugars, it is suggested that b-galactosidase treated whey could make a better substrate for industrial fermentation than untreated whey.

9.2.3 Spent Sulfite Liquor

The sulfite process involving the delignification of wood with acid bisulfite is widely used by mills in Europe and North America. While the lignin part is solubilized by combining with HSO3, the wood cellulose largely remains unde­graded. The hemicelluloses are hydrolyzed into monosaccharides. Spent sulfite liquor (SSL), which consists of lignin sulfonates, hexoses and pentoses, polysaccharides, galacturonic and acetic acid, some resins and unconsumed bisulfite, and ash, creates a major pollution problem when discharged into receiving water. Being the source of different types of carbohydrates, it has the potential for conversion into ethanol.

9.2.4 Bioethanol from Algae

The production of motor fuel from algae has been subjected to research for dec­ades. Now, there is an opportunity to produce bioethanol simultaneous to the third — generation biofuel—algae diesel (Oligae). Carbohydrates in algae oil can still be converted into starch that can be used for ethanol production after hydrolysis into simple sugars.