Evaluation of ammonia fibre expansion (AFEX) pretreatment for enzymatic hydrolysis of switchgrass harvested in different seasons and locations

Abstract

BackgroundWhen producing biofuels from dedicated feedstock, agronomic factors such as harvest time and location can impact the downstream production. Thus, this paper studies the effectiveness of ammonia fibre expansion (AFEX) pretreatment on two harvest times (July and October) and ecotypes/locations (Cave-in-Rock (CIR) harvested in Michigan and Alamo harvested in Alabama) for switchgrass (Panicum virgatum).ResultsBoth harvest date and ecotype/location determine the pretreatment conditions that produce maximum sugar yields. There was a high degree of correlation between glucose and xylose released regardless of the harvest, pretreatment conditions, or enzyme formulation. Enzyme formulation that produced maximum sugar yields was the same across all harvests except for the CIR October harvest. The least mature sample, the July harvest of CIR switchgrass, released the most sugars (520 g/kg biomass) during enzymatic hydrolysis while requiring the least severe pretreatment conditions. In contrast, the most mature harvest released the least amount of sugars (410 g/kg biomass). All hydrolysates were highly fermentable, although xylose utilisation in the July CIR hydrolysate was poor.ConclusionsEach harvest type and location responded differently to AFEX pretreatment, although all harvests successfully produced fermentable sugars. Thus, it is necessary to consider an integrated approach between agricultural production and biochemical processing in order to insure optimal productivity.

Ethanol Production from Hydrothermally-Treated Biomass from West Africa

“…Moreover, the coconut husk was observed to have the highest lignin and extractives content, and the cellulose content (21.3%) was comparable to those (18.19 to 21.26%) obtained by Ding et al (2012) but considerably lower than the value (32%) observed by van Dam et al (2006). These differences were expected, since the components of biomass vary with species, location, and time/season of harvest, among others (Bals et al 2010). The lignin content was very low for elephant grass, at 12.4%, while the ash content was the highest, at 7.9%.…”

Pretreatment strategies for delignification of sugarcane bagasse: a review

“…Ammonia fiber expansion (AFEX) is a process in which liquid ammonia is added to the biomass under moderate pressure (100 to 400 psi) and temperature (70 to 200°C) before rapidly releasing the pressure (Bals et al 2010). This process decrystallizes the cellulose, hydrolyses hemicellulose, removes and depolymerises lignin and increases the size and number of micropores in the cell wall, thereby significantly increasing the rate of enzymatic hydrolysis (Mosier et al 2005).…”

Substrate-Specific Development of Thermophilic Bacterial Consortia by Using Chemically Pretreated Switchgrass

“…Samples were transported to the lab at room temperature and inoculated within 24 h. The ionic-liquid (IL)-pretreated switchgrass was prepared by heating switchgrass with 1-ethyl-3-methylimidazolium acetate as previously described and washed with water to remove the ionic liquid (11). Ammonium fiber expansion (AFEX)-pretreated switchgrass was prepared as previously described and washed with water after pretreatment to remove readily solubilized compounds (14). Untreated switchgrass was extracted with water and ethanol to remove soluble compounds (6).…”