Pervaporation of the low ethanol content extracting stream generated from the dealcoholization of red wine by membrane osmotic distillation

This paper presents as main contribution the combination of membrane osmotic distillation (OD) to dealcoholize red wine with hydrophobic-hydrophilic pervaporation (PV) carried out to add value to the wastewater (extracting water) produced in OD, recycling water and generating bioethanol. Membrane OD with a commercial polypropylene hollow fiber module was applied to partially dealcoholize red wine from 14.0 to 11.0 v/v% ethanol. The OD extracting water, containing only ca. 5.3 wt% ethanol, was treated by sequential PV with both hydrophobic (PDMS or zeolite silicalite-1) and hydrophilic (zeolites mordenite or faujasite) membranes. This hydrophobic-hydrophilic PV produced two main products: bioethanol (recovering 88% of the ethanol removed from the wine) and a 99.4 wt% water-rich product. This water-rich product, with a very low ethanol content, was used as extracting water in the OD, giving rise to an analogous partially dealcoholized wine, in terms of aroma contents (as determined by gas chromatography for 25 compounds), to that achieved when using fresh water.