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The inexpensive production of sugars from lignocellulose is an essential step for the use of biomass to produce fuel ethanol. Olive cake is an abundant by-product of the olive oil industry and represents a potentially significant lignocellulosic source for bioethanol production in the Mediterranean basin. Furthermore, converting olive cake to ethanol could add further value to olive production. In the present study, olive cake was evaluated as a feedstock for ethanol production. To this end, the lignocellulosic component of the olive cake was dilute-acid pretreated at a 13.5% olive-cake loading with 1.75% (w/v) sulfuric acid and heating at 160°C for 10 min. This was followed by chemical elimination of fermentation inhibitors. Soluble sugars resulting from the pretreatment process were fermented using E. coli FBR5, a strain engineered to selectively produce ethanol. 8.1 g of ethanol/L was obtained from hydrolysates containing 18.1 g of soluble sugars. Increasing the pretreatment temperature to 180°C resulted in failed fermentations, presumably due to inhibitory by-products released during pretreatment. © KSBB

Olive mill wastewater (OMWW) is a by-product of the olive oil extraction industry. Its dumping creates severe environmental problems in the Mediterranean countries. The phytoxicity of OMWW is due to the phenolic substances and is evaluated through a genotoxicity method. An aerobic treatment of OMWW was conducted during 45 days. Different concentrations of raw and treated OMWW were tested using the Vicia faba micronuclei test. Results showed that raw OMWW induced significant micronuclei formation at 10% of OMWW dilution. At 20% of dilution, no mitosis was recorded. The 45 days aerobic treatment OMWW showed an important decrease in the genotoxicity and also in the toxicity that was observed at 10% and 20% OMWW dilution. This could be correlated with the biodegradation of 76% of the total phenols. Indeed, qualitative analysis by high performance liquid chromatography shows the disappearance of the majority of phenolic compounds after 45 days of treatment. This study was completed by an agricultural test with V. faba plant. Data showed significant growth yield of 36.3% and 29.9% after being irrigated with 5 and 10 t/ha, respectively. These results supported the positive role of aerobic treatment on OMWW and their capacity to ameliorate the agronomic potential of these effluents.