Reducing water consumption in beet distilleries by recycling the condensates to the fermentation phase

Recycling the stillage condensates produced in beet distilleries into the fermentation phase, would enable both water consumption and wastewater rejection to be reduced. However, it has been demonstrated that at least eight compounds in these condensates caused the inhibition of alcohol production. Their retention by a reverse osmosis (RO) process and preparative chromatography was thus considered. The reverse osmosis treatment led to high rejection coefficients for all neutral compounds whatever the pH, but had to be carried out at basic pH to obtain an almost complete retention of the small acids. Adsorption isotherm measurements carried out on various chromatographic supports showed that acidic compounds were best retained on a weak anionic exchanger and other solutes on a non-polar adsorbent. The coupling of the RO process and chromatography could therefore be a viable alternative for the treatment of these effluents. (c) 2007 Elsevier Ltd. All rights reserved.