An effective acid pretreatment of agricultural biomass residues for the production of second-generation bioethanol

Abstract

Currently, the potential for energy recovery of plant biomass by biotechnological processes is a preferred solution for the use of agricultural products of low commercial value in order to produce bioenergy that is alternative to fossil fuels. The objective of this study was to obtain second-generation bioethanol by valorization of sugar beet and common dates of low quality. This involved separate hydrolysis and anaerobic fermentation process using the yeast strain Saccharomyces cerevisiae. Physicochemical and biochemical analyzes were carried out on beet and date substrates before and after alcoholic fermentation to determine their effect on yeast activity. The results showed that palm date was a good substrate for the microorganisms in contrast to sugar beet which required a high pretreatment in order to hydrolyze sucrose into fermentable sugars. After distillation, it was possible to recover bioethanol with a quality and a concentration depending on the substrate nature. For an initial sugar concentration of 12.0 °Brix, 74.7 g/kg DM of bioethanol (92.4 g/L) was produced by Saccharomyces from date syrup. In the presence of concentrated date syrup (22.2 °Brix), a lower efficiency of ethanol production was observed (78.2 g/L). It can be conclude that the diluted date substrate led to a good quality bioethanol with a high production yield. Statement of noveltyIn this project, we tried to valorize agricultural residues (Algerian sugar beet and palm date of low quality) for the production of bioethanol which can substitute fossil energies. Algeria is considered as one of the major producers and exporters of palm dates in the world, and thousands of tons of dates remain unused. Thus, these agricultural by-products could be recovered instead of being released into the environment by polluting it. In order to produce bioethanol, an effective pretreatment and optimal fermentation conditions were used. This project is part of a strategy to increase the feedstock exploitation and decrease the residues while producing clean and renewable energy.* Nabila Khellaf, khellafdaas@yahoo.fr |