Continuous Ethanol Production from Molasses via Immobilized Saccharomyces cerevisiae on Different Carriers on Pilot Scale

Abstract

IMMOBILIZATION of yeast cells for continuous ethanol production has been extensively studied worldwide during the past few years because it showed significant advantages compared to the production by free cell system. Using renewable substrates such as Egyptian cane and beet molasses becomes necessary to reduce food crops for bioethanol production. This study investigates the immobilization of commercial strain of Saccharomyces cerevisiae on different carriers (sugarcane bagasse, rice straw, wheat straw, and Na-alginate) for continuous ethanol production on a pilot scale. The results demonstrated that sugarcane bagasse was the best carrier for yeast cell immobilization. This substrate produced 66.30g/ L ethanol, 2.76g/ L/ hr as ethanol productivity, and 81% fermentation efficiency from the theoretical value, using a mixture of Egyptian cane and beet molasses with 16% initial sugar at 30°C and pH 4.5. Also, the production process is retained until 18 days continuously. From this study, it was clear that lignocellulosic materials provide suitable, cheap, and renewable carriers for immobilization of yeast cells used in the continuous ethanol production process.