title: Subcritical hydrothermal pretreatment of olive mill solid waste for biofuel production.
abstract: The hydrothermal pretreatment of olive mill solid waste amended with 0.6M organic acids was studied at temperatures between 100 and 170°C. Acetic and formic acids which are endogenous intermediates of hemiacetyl splitting at subcritical conditions were tested. Formic acid, with smaller molecular size and lower pKa, was found to be more effective than acetic in the entire range of temperatures tested. Yield of enzymatic hydrolysis was significantly enhanced (>2 folds) at temperatures above 140°C. Concentration of aldehyde byproducts in the medium increased with temperature and pressure and addition of organic acids, however, the highest concentration detected (ca 1g/L) did not surpass values reported as inhibitory of sugars fermentation to ethanol by either yeast or bacteria. Aldehyde production was more affected by temperature than by acid addition. Concluding, addition of formic acid to hydrothermal pretreatment at relatively mild temperatures (140-170°C) and pressure (10-13 atm) improved saccharification yield while saving energy.
authors.affiliation: Institute of Applied Research (Affiliated with University of Haifa), The Galilee Society, P.O. Box 437, Shefa-Amr 20200, Israel; University of Haifa, 199 Aba Khoushy Ave., Mount Carmel, Haifa, Israel. Electronic address: hebaabutayeh@yahoo.com.
authors.forename: Hiba
authors.initials: H
authors.lastname: Abu Tayeh
authors.affiliation: Division of Environmental, Water & Agriculture Engineering, Faculty of Civil and Environmental Engineering, Technion Institute, Haifa 32000, Israel.
authors.forename: Odelia
authors.initials: O
authors.lastname: Levy-Shalev
authors.affiliation: Institute of Applied Research (Affiliated with University of Haifa), The Galilee Society, P.O. Box 437, Shefa-Amr 20200, Israel; Tel Hai College, Upper Galilee, 12208, Israel. Electronic address: azaizeh1955@yahoo.com.
authors.forename: Hassan
authors.initials: H
authors.lastname: Azaizeh
authors.affiliation: Division of Environmental, Water & Agriculture Engineering, Faculty of Civil and Environmental Engineering, Technion Institute, Haifa 32000, Israel. Electronic address: carlosd@tx.technion.ac.il.
authors.forename: Carlos G
authors.initials: CG
authors.lastname: Dosoretz
mesh_terms: D056804:Biofuels / Q000032:analysis*; D001709:Biotechnology / Q000379:methods*; D002264:Carboxylic Acids / Q000494:pharmacology; D002482:Cellulose / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation / Q000187:drug effects; D005662:Furaldehyde / Q000031:analogs & derivatives / Q000378:metabolism; D006868:Hydrolysis; D031658:Olea / Q000737:chemistry*; D010084:Oxidation-Reduction / Q000187:drug effects; D011134:Polysaccharides / Q000378:metabolism; D011312:Pressure; D062611:Solid Waste; D013464:Sulfuric Acids / Q000494:pharmacology; D013696:Temperature; D014908:Triticum / Q000187:drug effects; D014867:Water / Q000737:chemistry*
chemical_list: D056804:Biofuels; D002264:Carboxylic Acids; D011134:Polysaccharides; D062611:Solid Waste; D013464:Sulfuric Acids; D014867:Water; D000431:Ethanol; C008046:5-hydroxymethylfurfural; C007916:hemicellulose; D002482:Cellulose; D005662:Furaldehyde; C033158:sulfuric acid
keywords: Bioethanol production; Lignocellulose hydrolysis; Liquid hot water; Olive mill solid wastes; Pretreatment