Reducing energy for cellulose ethanol production by the use of sterilising agents in lieu of steam

The use of sterilising agents in lieu of energy intensive steam sterilisation was investigated for cellulose ethanol fermentations. Sodium metabisulphite and hydrogen peroxide were added to a number of simultaneous saccharification and fermentations of wheat straw to ethanol and their effects on acetic acid, lactic acid, glucose and ethanol production were measured. Hydrogen peroxide and sodium metabisulphite both limited the growth of acetic and lactic acid bacteria, without adversely impacting on cellulase performance. At the higher dosage of sodium metabisulphite (2.14 g/L) there was some evidence of inhibition of yeast action. A dosage of 5.44 g/L hydrogen peroxide resulted in a 52% reduction in acetic acid, complete elimination of lactic acid, and a 20% increase in ethanol production. Hydrogen peroxide is hence considered a potential alternative to steam for scale-up.