Recovery of materials from the wastewater from wine distilleries by drying the mixture of solid and liquid wastes

Abstract

INTRODUCTION THE PRODffCT[ON of 1 million hectolitres of wine gives 20,000-25,000 tons of by-products, an average of 6000 tons of wine dregs and 16,000 tons of (pressed grapes), containing 55-60 per cent of moisture. One ton of marc is composed of 249 kg of rafles,~. 225 kg of grape stones and 425 kg of grape pellicles. After distillation the pressed grapes are in general dried and the grape stones are separated from the stalks and pellicles, then ground to extract their content of edible oil, about 10 per cent of their weight. The dry stalks and pellicles constitute the mould. Distillation of pressed grapes and of wine dregs separates alcohol from wastes. When 1 ton of pressed grapes is treated by a diffusion process, the volume of effluent reaches 1-1.300 m 3 but by repeated recycling (15-20 times) the volume of spent wine is much lessened and does not exceed 50-70 1. ton-1 of marc. The wine dregs are first dried in order to separate the tartar, then diluted to facilitate their flow through the distillation pipes; the volume of water is one and a half or two times that of the dregs distilled. From 1 ton of pressed-grapes 200 kg of mould dried to a percentage of 10 per cent humidity are obtained. The mould and dregs in the waste are in the relative propor t ion0f 1:5 to 4:5. Until recently the effluent of wine dregs distillation was disposed of by lagooning or discharging it to a water-course. Undiluted waste has a BOD5 of more than 100,000. A wine distillery discharging 100 m 3 effluent per day produces a level of pollution equal to that of a town of 200,000 inhabitants.