Lessons learned from 100 years of fermenting complex sugar sources

As one of relatively few traditional pulp and paper mills Borregaard has successfully transitioned to become an advanced biorefinery positioned within lignin performance chemicals, specialty cellulose, wood based vanillin and 2G ethanol produced from spruce. The spent sulfite liquor (SSL) generated during the sulfite cooking process contains hexose and pentose sugars originating from spruce hemicellulose. The hexose sugars are utilized in a continuous fermentation process yielding 20 million liters of ethanol yearly, which makes Borregaard the world’s largest producer of wood based ethanol. Borregaard has directed substantial resources towards development of the BALI™ biorefinery concept. The concept comprises a pretreatment of lignocellulosic biomass that yields a liquid SSL and a cellulose pulp. Subsequently, the pulp is hydrolysed enzymatically to monosaccharides. The sugars in the SSL and the pulp hydrolysate can then be fermented to ethanol, utilizing the fermentation know-how generated at the Borregaard sulfite ethanol plant.