A Process To Treat High-Strength Brewery Wastewater via Ethanol Recovery and Vinasse Fermentation

Certain wastewaters from breweries (purges from fermentation processes, discarded beer, etc.) can exhibit a chemical oxygen demand (COD) as high as 170 000 mg of O₂/L, which is due to the ethanol and carbohydrates remnants from the fermentation process. These effluents can represent up to 3% of the volume of beer produced and must be treated prior to their discharge into the environment, which is currently accomplished in conventional treatment plants that typically have anaerobic reactors (e.g., upflow anaerobic sludge blanket, UASB) and use a follow-up aerobic treatment. In this work, a process that distills ethanol contained in these effluents and ferments vinasses to enhance the ethanol production was developed, and its technical–economic feasibility was studied. The process allows the organic load to be depleted by 88% at a rate that is 15 times faster than that of conventional processes. In addition, a valuable product, i.e., ethanol, is produced