A Whole-Slurry Fermentation Approach to High-Solid Loading for Bioethanol Production from Corn Stover

Pablo G Del Río,Gil Garrote,F.R Rebelo,Patricia Gullón,Aloia Romaní,Beatriz Gullón

doi:10.3390/agronomy10111790

Abstract

Corn stover is the most produced byproduct from maize worldwide. Since it is generated as a residue from maize harvesting, it is an inexpensive and interesting crop residue to be used as a feedstock. An ecologically friendly pretreatment such as autohydrolysis was selected for the manufacture of second-generation bioethanol from corn stover via whole-slurry fermentation at high-solid loadings. Temperatures from 200 to 240 °C were set for the autohydrolysis process, and the solid and liquid phases were analyzed. Additionally, the enzymatic susceptibility of the solid phases was assessed to test the suitability of the pretreatment. Afterward, the production of bioethanol from autohydrolyzed corn stover was carried out, mixing the solid with different percentages of the autohydrolysis liquor (25%, 50%, 75%, and 100%) and water (0% of liquor), from a total whole slurry fermentation (saving energy and water in the liquid–solid separation and subsequent washing of the solid phase) to employing water as only liquid medium. In spite of the challenging scenario of using the liquor fraction as liquid phase in the fermentation, values between 32.2 and 41.9 g ethanol/L and ethanol conversions up to 80% were achieved. This work exhibits the feasibility of corn stover for the production of bioethanol via a whole-slurry fermentation process.

Highlights

Environmental, social, and economic issues worldwide regarding overpopulation and the excessive usage of fossil-related fuels are leading to the search for new, alternative, and sustainable kinds of energy [1,2]
High values of glucan-to-glucose conversion (GGC) of 86.7–94.1% at 72 h, becoming a suitable almost quantitative conversions glucan to glucose when solid achieved for the subsequent fermentation process.of Romaní in etenzymatic al. (2010)hydrolysis achieved almost employing temperatures of autohydrolysis of
These results demonstrate faster and higher ethanol production when employing the solid and liquid phase from autohydrolysis at 230 ◦ C

Summary

Introduction

Environmental, social, and economic issues worldwide regarding overpopulation and the excessive usage of fossil-related fuels are leading to the search for new, alternative, and sustainable kinds of energy [1,2]. In this context, the employment of promising lignocellulosic materials (LCM) as a renewable source for the production of biofuels, following a biorefinery approach, is essential in a circular economy point of view [3,4,5]. Corn stover is the Agronomy 2020, 10, 1790; doi:10.3390/agronomy10111790 www.mdpi.com/journal/agronomy

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