Abstract
The winemaking industry generates a significant amount of waste annually, including wine lees, a by-product rich in bioactive compounds such as polyphenols. These compounds, known for their antioxidant and healthpromoting properties, present an opportunity for the valorisation of wine residues into high-value products for the food, cosmetic, and pharmaceutical industries. To achieve a more sustainable management of these residues, the use of green technologies, such as membrane technology, offers a solvent-free alternative for polyphenol recovery. This study focuses on optimising the ultrafiltration process for the treatment of wine lees, aiming to obtain a clarified effluent suitable for further concentration with nanofiltration or reverse osmosis. Ceramic membranes (10 and 1 kDa) and a polymeric membrane (5 kDa) were tested to assess their effectiveness in polyphenol rejection and fouling behaviour during filtration. The 5 kDa step exhibited the highest rejection rates (RTyrosol = 48 %, RGallic Acid = 66 %, RTrolox = 44 %), suggesting pore blockage by larger molecules, making it crucial for effluent purification before further filtration. The 10 kDa membrane showed lower rejection (RTyrosol = 27 %, RGallic Acid = 29 %, RTrolox = 25 %), while the 1 kDa membrane also presented low rejection (RTyrosol = 24 %, RGallic Acid = 30 %, RTrolox = 11). Ceramic membranes demonstrated better permeability recovery after chemical cleaning (95 % for 10 kDa and 94 % for 1 kDa), while the polymeric membrane had poor recovery (26 %). Fouling analysis using Hermia's models revealed intermediate and complete blocking as prevailing mechanisms.
