Miscanthus-Derived Boiethanol: Experience of Primary Set-Up

Abstract

In industrial chemistry, there is a growing demand for the precursors obtained by bioengineering methods; particularly, bioethanol can be used for the production of ethylene. In this study, Miscanthus sacchariflorus was used for the first time as a feedstock for the production of bioethanol. The step of miscanthus chemical treatment with a 4 wt.% solution of nitric acid was successfully scaled up under the conditions of pilot-plant production; the product of nitric acid treatment (PNAT) was obtained with the yield of 37.4 % and the content of hydrolyzed components equal to 96.0 %. It was shown that the chemical pretreatment of miscanthus with nitric acid, irrespective of its breed, makes it possible to obtain substrates with close chemical compositions. The goal of the study was to perform the primary scale-up of the joint saccharification-fermentation of miscanthus-derived PNAT in an 11 L fermenter (at a scaling factor 1 : 8) with increasing the PNAT concentration from 60.0 to 90.0 g/L. Saccharification was carried out using the commercially available enzymatic preparations Cellolux-A and Bruzyme BGX, and fermentation – using the VKPM yeast strain Saccharomyces сerevisiae Y-1693. It was found that as the substrate concentration is raised from 60.0 to 90.0 g/L, the concentration of bioethanol increases by 9.5 g/L; the substrate concentration of 90.0 g/L was recommended for use in the process scale-up for the pilot-plant production. A scheme of bioethanol production yielding 202 L of bioethanol from ton of miscanthus was proposed.