Grape Winery Waste as Feedstock for Bioconversions: Applying the Biorefinery Concept

Grape wine is among the most important alcoholic beverages in the globe, with a continuously rising world demand, currently sizing at 25 billion litres. Such a large and heavily industrialised market calls for the maintenance of a steady production of raw materials to end products. Consequently, intensive cultivation of land, harvesting of the goods and manufacturing for the production of commercially available products are being implemented. Wine making is a timed, multistage process producing a large amount of organic and inorganic waste. It has been calculated that during cultivation and harvesting about 5 tonnes of solid waste are generated per hectare per year, while the winery wastewater varies according to the production size from 650,000 m3 (Greece) to over 18,000,000 m3 (Spain) per year. Conventional treatments of winery waste are becoming increasingly expensive, demanding significant amounts of effort, resources and energy for safe waste discharge. Therefore, the need to recycle, reuse and recover energy and valuable chemicals from winery waste and wastewater becomes apparent. Valorisation of winery waste is possible when introducing the concept of biorefinery, i.e. the use of winery waste as bioconversions feedstock in order to produce platform chemicals, biofuels, heat and energy.