abstract
Biofuels are suitable alternatives to conventional and fossil fuels that pose serious environmental adverse effects to society. Bioethanol is the most promising biofuel and can be generated from lignocellulosic biomasses. Forest residues are outside the human food chain and inexpensive raw materials, but they need a previous pretreatment, in order to improve the cellulose accessibility for further bioconversion. The study of bioethanol production from rockrose pretreated by steam explosion (SE) was carried out employing separate enzymatic hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF) approaches. Saccharification of untreated rockrose attained only 0.9% of sugars yield. However, the steam explosion pretreatment promoted the disruption of interfibrillar surfaces of fibers with partial degradation of lignin thus enhancing the accessibility of polysaccharides toward enzymatic hydrolysis. Alkaline extraction after steam explosion pretreatment of rockrose residue (R-SE-OH) led to the partial removal of lignin, hemicelluloses, and other degradation products from fibre surface allowing an increase of 75% in the glucose yield. Bioethanol production in SSF mode was faster and slightly more efficient process than SHE providing the best results: ethanol concentration of 16.1 g L-1, fermentation efficiency of 69.8% and a yield of 22.1 g ethanol/100 g R-SE-OH. (C) 2015 Elsevier B.V. All rights reserved.
keywords
ETHANOL-PRODUCTION; ENZYMATIC-HYDROLYSIS; WHEAT-STRAW; ACID PRETREATMENT; CORN STOVER; LIGNOCELLULOSIC BIOMASS; OLIVE STONES; OPTIMIZATION; FRACTIONATION; CELLULOSE
subject category
Biotechnology & Applied Microbiology; Engineering
authors
Ferro, MD; Fernandes, MC; Paulino, AFC; Prozil, SO; Gravitis, J; Evtuguin, DV; Xavier, AMRB
our authors
Ana Maria Rebelo Barreto Xavier
Assistant Professor
Dmitry Evtyugin
Associate Professor with Aggregation
Sónia Oliveira Prozil
Research Fellowshipacknowledgements
This research was co-financed by INALENTEJO 2007-2013/QREN, within the project BioEcos-Valorizacao Integrada de Biomassa. CICECO is Associated Laboratory of the Portuguese Ministry of Science, Technology and Higher Education, being partially supported by FCT, the Portuguese Foundation for Science and Technology by Pest-C/CTM/LA0011/2013 contract. The authors would like to thank Associacao de Defesa do Patrimonio de Mertola (ADPM), for kindly supplying the Cistus ladanifer. The steam explosion treatment of biomass has been supported by the Latvian National Research Programme