My Research internship, in the context of a Transnational BRISK2 “Biofuels Research Infrastructure for Sharing Knowledge 2”project, was achieved during April 2018 in ENEA – Italian National agency for new technologies, Energy and sustainable economic development – Centro Ricerche Trisaia – Italy. 

The application to the BRISK2 was very easy and simple with the collaboration of Dr. Francesco Zimbardi from the “Bioenergy, Biorefinery and Green Chemistry Division” in ENEA. 

The ENEA Centro Ricerche Trisaia is very well equipped in terms of pretreatments facilities in lab and full scales, viz.: Batch Steam Explosion Reactor; Steam Explosion Full Scale Plant; High pressure and temperature batch reactor.   

 The work target was to compare the efficiency of two physico-chemical pretreatments, viz.: Steam Explosion (SE) and Hot Water/OrganoSolv (OS) towards acid fractionation of OWW and enzymatic digestibility of the cellulosic residue. In fact, the olive woody waste (OWW) is a promising feedstock for biorefineries in the Mediterranean region. In fact, for each ton of olive oil produced, 4 tons of OWW are generated. Thus, this feedstock is considered as a potential lignocellulosic feedstock for 2G sugars production. In order to valorize this lignocellulosic residue, a pretreatment is necessary to fractionate its components and to improve the cellulose enzymatic hydrolyzability.  

The Steam Explosion was performed with a batch reactor of 10 L, coupled with a 125 kW boiler. The Hot Water/OrganoSolv was carried out a batch reactor (PARR) of a 0.5 l vessel with adjustable internal stirrer and heat control. After SE and OS pretreatments the materials were extracted by water to remove the soluble hemicellulose as monomers and oligomers as well the inhibitors; the solid residue was saccharified at the solids loading of 5% (w/v), 50°C and pH 4.8 for 72h with a stirring speed of 180 rpm.  

This research emphasized that for OWW Steam Explosion allowed slight higher recovery of glucose sugars by aqueous extraction, also because of a lower production of inhibitors. On the other side, the Hot Water/OrganoSolv pretreatment showed better performances in terms of hemicellulose sugars recovery and enzymatic hydrolysis yield. 

The work was very fruitful. The main results of this work were presents in the 26th European Biomass Conference and Exhibition –EUBCE from 14 to 18 May 2018 in Copenhagen – Denmark.  

Acknowledgements 

I’m very grateful for the team of the “Bioenergy, Biorefinery and Green Chemistry Division” in ENEA Centro Ricerche Trisaia, especially to: Dr.Francesco Zimbardi, Dr. Egidio Viola, Dr. Nadia Cerone, Dr. Vito Valerio and Dr. Assunta Romanelli for their help, availability and collaboration in a very nice teamwork atmosphere. 

I would like also to express my thankfulness to the EC in the frame of H2020 program, through the BRISK2 project, contract 731101, for the financial support to achieve this work.