Vacuum-assisted production of hydrogen and volatile fatty acids from lignocellulosic biomass derived from energy-crops pruning

Abstract

Energy crops are promising sources of liquid biofuels, but large amounts of lignocellulosic biomass must be harvested from these cultivations, which have remained unexplored to produce additional chemicals and energy. In the present study, pruning derived from energy crops (Jatropha curcas and Ricinus communis) was evaluated, for the first time, as feedstock for the production of hydrogen (H2) and volatile fatty acids (VFA) by anaerobic sludge. The highest H2 production rate and yield were obtained with hydrolysate derived from J. curcas, producing up to 44.6 mL H2/L-h and 66.6 mL H2/g residue. Application of intermittent vacuum increased the production of H2 (up to 5-fold) and VFA (up to 3-fold) as compared to fermentations performed without vacuum. This study proposes an integrative exploitation of these energy crops, by harnessing their pruning to produce extra fuels and chemicals within a bio-refinery framework.