Tuesday, April 20, 2010
LL Conference Facility (Hilton Clearwater Beach)
The mechanical grinding of biomass as pretreatment for subsequent bioconversion, such as the enzymatic hydrolysis, is an efficient method but in the case of lignocellulosic biomass it is not so convenient due to the high energy consumption. The concept at the basis of this work is that torrified biomass is brittle and has higher grindability than fibrous biomass; this property can be exploited to achieve particle size reduction with lower energy input. The aim of the carried out experiments has been to preliminary investigate the overall effectiveness of coupling torrefaction and grinding in terms of sugar and ethanol yields. Biomass obtained from olive pruning has been torrified at different conditions, namely at 180 - 280°C for 60 -120 min. , grinded with mill having sieve of 50 mesh (0.32 mm), and used as substrate in SSF experiments. The bioconversion has been carried out at flask scale using a mix of cellulosolytic, hemicellulosolitic and β-glucosidase enzymes, and a commercial strain of Saccharomyces cerevisiae. The comparison between the bioconversion yields achieved using grinded biomass or torrified + grinded biomass highlighted that: 1) Mild torrefaction conditions limit sugar degradation within 5-10 percent; 2) Torrified biomass do not lead to enzymatic and fermentation inhibition. How a torrefaction step could be integrated in an ethanol production process has been preliminary estimated, above all as regard the energy integration. The new developed concept has been patented.