Comparing oxidative and dilute acid wet explosion pretreatment of Cocksfoot grass at high dry matter concentration for cellulosic ethanol production

Abstract

The choice of a suitable pretreatment method and the adjustment of the pretreatment parameters for efficient conversion of biomass are crucial for a successful biorefinery concept. In this study, cocksfoot grass, a suitable lignocellulosic biomass with a potential for large-scale production was investigated for cellulosic ethanol production. The biomass raw materials were pretreated using wet explosion (WEx) at 25% dry matter concentration with addition of oxygen or dilute sulfuric acid. The enzymatic hydrolysis of cellulose was significantly improved after pretreatment. The highest conversion into cellulose monomeric C6 sugars was achieved for WEx condition AC-E (180°C, 15 min, and 0.2% sulfuric acid). For that condition, the highest ethanol yield of 197 g/kg DM (97% of theoretical maximum value) was achieved for SSF process by Saccharomyces cerevisiae. However, the highest concentration of hemicellulose C5 sugars was found for WEx pretreatment condition O2-A (160°C, 15 min, and 6 bar O 2 ) which means that the highest potential ethanol yield was found at this moderate pretreatment condition with oxygen added. Increasing the pretreatment temperature to 180-190°C with addition of oxygen or dilute sulfuric acid significantly degrades the solubilized hemicellulose sugars and thus, achieved the highest formation of by-products.

Structural Analysis of Alkaline Pretreated Rice Straw for Ethanol Production

“…The value of the theoretical ethanol yield in this study is comparable to previous report on SSF with S. cerevisiae [30,31].…”

“…The yeast S. cerevisiae was activated to the exponential growth phase prior to SSF and the relatively high amount of yeast cells was used, thus resulting in no lag phase over 96 h SSF ( Figure 6) and improving ethanol yield [30,32]. In addition, the yeast strain has been reported to tolerate towards fermentation inhibitors and efficiently ferments glucose to ethanol [33].…”

Increasing the Production of Volatile Fatty Acids from Corn Stover Using Bioaugmentation of a Mixed Rumen Culture with Homoacetogenic Bacteria

“…Unlike conventional pretreatment methods, this method uses no harsh chemicals that can be detrimental to microbes during fermentation. Only low concentrations of inhibitory degradation products like furfural and hydroxymethylfurfural are produced during WEx, and the pretreated material is ready for further processing by enzymes and/or microbes [ 7 ].…”

Effects of the liquid vapor oxygen transfer coefficient (kLα) on ethanol production from cassava residue and analysis of the fermentation kinetics

“…Ethanol produced from biomass, and the main components of it including cellulose, hemicellulose, and lignin , as a new energy source is currently a major research area for sustainable development. The main product of cellulose hydrolysis is glucose, and hemicellulose hydrolysates are mainly xylose .…”