Steam pretreatment of dry and ensiled industrial hemp for ethanol production

Abstract

International audienceBiomass can be converted into liquid and gaseous biofuels with good efficiency. In this study, the conversion of industrial hemp ( L.), a biomass source that can be cultivated with a high biomass yield per hectare, was used. Steam pretreatment of dry and ensiled hemp was investigated prior to ethanol production. The pretreatment efficiency was evaluated in terms of sugar recovery and polysaccharide conversion in the enzymatic hydrolysis step. For both materials, impregnation with 2% SO followed by steam pretreatment at 210°C for five minutes were found to be the optimal conditions leading to the highest overall yield of glucose. Simultaneous saccharification and fermentation experiments carried out with optimised pretreatment conditions resulted in ethanol yields of 163 g kg ensiled hemp (dry matter) (71% of the theoretical maximum) and 171 g kg dry hemp (74%), which corresponds to 206-216 l Mg ethanol based on initial dry material

Thermal behavior of native, washed and steam exploded lignocellulosic biomass samples

“…The yields of these molecules significantly decreased from the steam exploded sample that indicates the reduction of the hemicellulose component during the steam explosion in agreement with the literature data [4,[24][25][26][27][28]. This finding has been confirmed by the TG/MS curves of the samples (Fig.…”

“…The experimental conditions of the steam explosion pretreatments are given in Table 1. The pretreatment conditions have been selected based on optimization for increased enzymatic degradability (highest glucose conversion in enzymatic hydrolysis) for each biomass in earlier studies [4,[32][33][34][35]. The severity factor (R 0 ), introduced by Overend and Chornet [36], is given in Table 1 for each steam exploded sample.…”

“…Plants with high cellulose content can be used as raw materials in the second generation bioethanol process [2][3][4][5] to produce the ethanol ecologically more competitive in comparison with the starch-and sugar-based ethanol production [6].…”

“…Cellulose can be converted to its building monomer -glucose -by cellulase enzyme complex [2][3][4][5]. The main function of hemicellulose and lignin is to make the cell wall more consistent and to protect cellulose fibrils against the attack of the cellulose degrading microorganisms.…”

Sulfur Trioxide Micro-Thermal Explosion for Rice Straw Pretreatment

“…Therefore, various pretreatments remove or alter the hemicellulose or lignin and decrease the crystallinity of cellulose to enhance enzymatic hydrolysis efficiency (Goering, et al, 1970;Mosier et al, 2005;Zhao et al, 2009). The major methods include pretreatment by milling (Sato et al, 2009;Delgenés et al, 2002;Chang and Holtzapple, 2000;Palmowski and Muller, 1999), acid (Keikhosro K, 2006;Nguyen, Q, 2004;Ye and Jay, 2005;Taherzadeh and Karimi, 2007;Iranmahboob, F, 2002), steam explosion (Mukhopadhyay and Fangueiro, 2009;Brownell et al, 1986;Negro et al, 1992), liquid hot water (Liu and Wyman, 2005), alkali (Das and Chakraborty, 2009;Goswami et al, 2009;Fengel and Wegener, 1984;Laser et al, 2002), wet oxidation (Palonen and Thomsen, 2004;Kumar and Wyman, 2009), ammonia fiber explosion (AFEX) (Taherzadeh and Karimi, 2008;Li et al, 2009;Zheng et al, 1998;Wu et al, 1999), SO2 catalyzed steam explosion (Balint and Emma, 2010) etc. Although these common pretreatments have made great successes in recycling cellulose from lignocellulosic biomass, they are not appropriate enough for biofuel production by industrialization if considering the disadvantages of them such as low efficient, huge energy consumption, high requirements for conditions of operations, environment pollution and so on.…”