Sustainable fermentation processing of two revalorized agro-industrial discards: carrot and brewer's yeast

Abstract

An integrated and sustainable fermentation process was developed which enabled both the revalorization of two regional agro-industrial discards as well as by-product reuse. Carrot and brewer's yeast, which are commonly used for animal feed, were processed to obtain 77.5 L of ethanol, 450 kg of solid waste called bagasse, 970 L of liquid effluent called vinasse, and 39.8 kg CO2 per each ton of discarded carrot. Results showed that the obtained bagasse was suitable for feeding 55 animals (calfs). The dilution of vinasse with fresh water (1:5) satisfied the requirements necessary to be used as beverage for the same number of animals, leaving a remnant which could be newly diluted (1:5) and used to irrigate a 0.025-ha carrot crop, the land dimension required to grow 1 ton of carrot.