Enzymatic hydrolyses of pretreated eucalyptus residues, wheat straw or olive tree pruning, and their mixtures towards flexible sugar-based biorefineries

Eucalyptus residues, wheat straw, and olive tree
pruning are lignocellulosic materials largely available in
Southern Europe and have high potential to be used solely
or in mixtures in sugar-based biorefineries for the production
of biofuels and other bio-based products. Enzymatic hydrolysis
of cellulose is commonly used in this context, but its high
efficiency is mandatory for cost-competitive biorefineries.
The influence of pretreatment severity (hydrothermal at
210–230 °C), enzyme dosage (8–24 FPU/gsolids), and solid
loading (5–20 % w/v) as key factors on enzymatic hydrolysis
efficiency was studied by 23 complete factorial central composite
design followed by response surface methodology
analysis, towards the optimization of glucose recovery from
individual feedstock or their mixtures. Optimized conditions
for enzymatic hydrolysis at 20 % (w/v) solids reached glucose
recoveries between 80 and 110 g/L for individual feedstock
and 85–92 g/L for mixtures and yields over 80 %.