Bioconversions of olive oil mill wastewaters blends

Abstract

The ability of the anaerobic mixed bacterial culture from an upflow anaerobic sludge blanket (UASB) bioreactor to convert blends of olive mill wastewaters (OMWs) with synthetic glucose medium or molasses into ethanol simultaneously with organic acids (OAs) was studied in the present work. All fermentations were conducted by free cells under non-aerated conditions at 37 °C and the effect of OMWs concentration on ethanol and OAs production was investigated. The highest amount of bioethanol (14.7 g L -1 ) was produced during fermentation of 45% v/v OMWs mixed with synthetic glucose medium (5% w/v) in only 28 hours. In mixtures of 30% v/v OMWs and molasses solution (3 °Be) 13.4 g L -1 of bioethanol were produced. Also, 16.2 g L -1 of succinic acid were produced, when 65% v/v OMWs mixed with synthetic glucose medium. Moreover, totally 11.6 g L -1 of varied OAs (succinic, malic, butyric and acetic) observed in mixtures of 35% OMWs with molasses. Finally, it has been shown that the 14 C-labelled glucose uptake rate (GUR) by biomass was strongly correlated to fermentation rate.