New insights into wine waste management: Zero waste discharge-driven full energy/resource recovery strategy

Abstract

This study developed an innovative strategy for wine waste management towards zero-waste discharge with full energy and resource recovery. Waste grape seed, as one of the most typical wine wastes, was first treated by aqueous ethanol, after that the grape seed oil and polyphenols were recycled, and the rest of solid residues were subjected to anaerobic digestion for methane production. It was found that the obtained grape seed oil was rich in about 82% of unsaturated fatty acids, of which all the parameters met the vegetable oil standard, this in turn suggested that the harvested grape seed oil was a high value-added and safe edible oil. While the produced polyphenols with outstanding antioxidant and antibacterial activity respectively verified by DPPH and ABTS radical scavenging assays and MIC and agar well diffusion assays could be used as food additives. Furthermore, the generated digestate after anaerobic digestion could meet all the requirements for organic fertilizer standard. Based on the obtained data from aqueous ethanol extraction and anaerobic digestion, it was estimated that about 122.2 kg of grape seed oil, 23.8 kg of polyphenols, 109.3 m3 of methane and 352.3 kg of organic fertilizer could be produced from 1 ton of grape seed by adopting the proposed strategy. As such, it is expected that this study may lead to the paradigm shift in wine waste management with the ultimate target of zero waste discharge.