Optimization of the operating conditions for the removal of alcoholic insoluble compounds contained in sugar beet vinasse
Résumé
The purification of sugar beet distillery vinasse, a by-product of bioethanol manufacturing, was studied
with a view to removing the insoluble compounds by precipitation in ethanol. Two influential operating
parameters, i.e. temperature and ethanol:vinasse (w/w) ratio of the precipitation, were optimized by a
simplex method. An optimum was reached for a weight ratio of 4.6 at 21 ◦C, that allowed 52.4% of the
vinasse dry matter to be separated. Additional experiments were then carried out to establish a secondorder
polynomial model from a Doehlert design and measure theweight of solid removed as a function of
temperature and ethanol:vinasse (w/w) ratio used. In the experimental domain studied, results showed
the veryweak positive influence of temperature and theweak negative influence of ethanol:vinasse (w/w)
ratio onweight of precipitate obtained. In addition, the statistical model enables to determine the response
surface in order to predict the variation in response when the values of variables are modified. Lastly,
the sugar beet precipitation was successfully scaled up, enabling a mass balance of the process to be
established. Results showed that a large proportion of proteins and pectins were separated during the
process.