Ammonia Fiber Expansion (Afex) Treatment of Wheat Straw for Production of Bioethanol

Ammonia Fiber Expansion (AFEX) treatment is a technique that is able to enhance the enzymatic hydrolysis yield of lignocellulosic materials. In this technique, lignocellulosic materials are treated by liquid ammonia under pressure followed by rapid release of pressure that expands the fiber structure and increases enzyme access to lignocellulose polysaccharides. However, the AFEX treatment variables such as the mass ratio of ammonia to lignocellulosic biomass, moisture of lignocellulose (moisture content of biomass), temperature, and residence time need to be evaluated to find the maximum efficiency of this treatment. The efficiency of the AFEX pretreatment was quantified by the yield of released sugars during enzymatic hydrolysis of the AFEX-treated wheat straw. The optimal treatment conditions for wheat straw were found to be: ammonia-to-wheat straw ratio, 1:1; temperature, 95°C; moisture content of wheat straw, 70% (dry weight basis); and residence time, 5 minutes. Under these conditions, almost 89% of the theoretical sugars were released by enzymatic hydrolysis of the AFEX-treated wheat straw. The enzymatic hydrolysis results showed the significance of AFEX pretreatment of wheat straw when compared to untreated wheat straw with released sugars yield of only 26 %.

Ammonia Fiber Expansion (Afex) Treatment of Wheat Straw for Production of Bioethanol

Ammonia Fiber Expansion (AFEX) treatment is a technique that is able to enhance the enzymatic hydrolysis yield of lignocellulosic materials. In this technique, lignocellulosic materials are treated by liquid ammonia under pressure followed by rapid release of pressure that expands the fiber structure and increases enzyme access to lignocellulose polysaccharides. However, the AFEX treatment variables such as the mass ratio of ammonia to lignocellulosic biomass, moisture of lignocellulose (moisture content of biomass), temperature, and residence time need to be evaluated to find the maximum efficiency of this treatment. The efficiency of the AFEX pretreatment was quantified by the yield of released sugars during enzymatic hydrolysis of the AFEX-treated wheat straw. The optimal treatment conditions for wheat straw were found to be: ammonia-to-wheat straw ratio, 1:1; temperature, 95°C; moisture content of wheat straw, 70% (dry weight basis); and residence time, 5 minutes. Under these conditions, almost 89% of the theoretical sugars were released by enzymatic hydrolysis of the AFEX-treated wheat straw. The enzymatic hydrolysis results showed the significance of AFEX pretreatment of wheat straw when compared to untreated wheat straw with released sugars yield of only 26 %.

Selecting a Biomass Pelleting Processing Depot Using a Data Driven Decision-Making Approach

Bioenergy is one of the potential solutions to satisfy the extensive demand for energy and reduce fossil fuel dependency. For biomass to be an efficient source of bioenergy, it must be converted to a usable form, one of which is pellets. This study compares three commonly used methods to produce pellets in a biomass depot and presents a framework to select the most effective and economic pelleting processes. The comparison is performed using a data driven decision-making method called the Preference Index Selection Method (PSI). We considered three main pelletization technologies and compared four of their most critical attributes. The three popular biomass pellet processing methods used for this study are the conventional pelleting process (CPP), the high moisture pelleting process (HMPP), and the ammonia fiber expansion (AFEX). These processes were evaluated from both economic and environmental perspectives. We used the state of Mississippi as a testing ground for our analyses. The results obtained through the PSI method were validated with the Grey relational analysis (GRA) method. The results revealed that of the three available pelleting processes, the conventional pelleting process and the high moisture pelleting process were the most economic and environmentally friendly.

Pretreatment of crop residues by ammonia fiber expansion (AFEX) alters the temporal colonization of feed in the rumen by rumen microbes

ABSTRACT This study examines the colonization of barley straw (BS) and corn stover (CS) by rumen bacteria and how this is impacted by ammonia fiber expansion (AFEX) pre-treatment. A total of four ruminally cannulated beef heifers were used to investigate in situ microbial colonization in a factorial design with two crop residues, pre-treated with or without AFEX. Crop residues were incubated in the rumen for 0, 2, 4, 8 and 48 h and the colonizing profile was determined using 16 s rRNA gene sequencing. The surface colonizing community clustered based on incubation time and pre-treatment. Fibrobacter, unclassified Bacteroidales, and unclassified Ruminococcaceae were enriched during late stages of colonization. Prevotella and unclassified Lachnospiraceae were enriched in the early stages of colonization. The microbial community colonizing BS-AFEX and CS was less diverse than the community colonizing BS and CS-AFEX. Prevotella, Coprococcus and Clostridium were enriched in both AFEX crop residues, while untreated crop residues were enriched with Methanobrevibacter. Several pathways associated with simple carbohydrate metabolism were enriched in the primary colonizing community of AFEX crop residues. This study suggests that AFEX improves the degradability of crop residues by increasing the accessibility of polysaccharides that can be metabolized by the dominant taxa responsible for primary colonization.

Effect of ammonia fiber expansion-treated wheat straw and a recombinant fibrolytic enzyme on rumen microbiota and fermentation parameters, total tract digestibility, and performance of lambs

The objective of this study was to evaluate the effect of ammonia fiber expansion (AFEX)-treated wheat straw pellets and a recombinant fibrolytic enzyme on the rumen microbiome, rumen fermentation parameters, total tract diet digestibility, and performance of lambs. Eight rumen cannulated wethers and 60 lambs (n = 15 per diet, 8 rams and 7 ewes) were used in a replicated 4 × 4 Latin square design digestibility study and a complete randomized growth performance study, respectively. Four treatment diets were arranged in a 2 × 2 factorial structure with AFEX wheat straw (0% or 30% AFEX straw pellets on a dietary DM basis replacing alfalfa hay pellets) and fibrolytic enzyme (with or without XYL10C, a β-1,4-xylanase, from Aspergillus niger) as main factors. Enzyme was applied at 100 mg/kg of diet DM, 22 h before feeding. Rumen bacteria diversity Pielou evenness decreased (P = 0.05) with AFEX compared with the control diet and increased (P < 0.01) with enzyme. Enzyme increased (P ≤ 0.02) the relative abundancies of Prevotellaceae UCG-004, Christensenellaceae R-7 group, Saccharofermentans, and uncultured Kiritimatiellaeota. Total protozoa counts were greater (P ≤ 0.04) in the rumen of lambs fed AFEX compared with control, with enzyme reducing (P ≤ 0.05) protozoa counts for both diets. Digestibility of DM did not differ (P > 0.10) among diets, but digestibility of CP was reduced (P = 0.001), and digestibility of NDF and ADF increased (P < 0.05) as AFEX replaced alfalfa. Compared with control, AFEX promoted greater DMI (P = 0.003) and improved ADG up to 42 d on feed (P = 0.03), but not (P = 0.51) over the full ~94-d experiment. Consequently, overall G:F was reduced (P = 0.04) for AFEX when compared with control (0.188 vs. 0.199), but days on feed were lower (P = 0.04) for AFEX (97 vs. 91 d). Enzyme improved DMI of AFEX up to day 70 (P = 0.01), but did not affect DMI of the control diet. Enzyme addition improved ADG of lambs fed both diets in the first 28 d (P = 0.02), but not over the entire feeding period (P ≥ 10). As a result, G:F was improved with enzyme for the first 28 d (P = 0.04), but not overall (P = 0.45). This study shows that AFEX-treated wheat straw can replace alfalfa hay with no loss in lamb growth performance. Additionally, the enzyme XYL10C altered the rumen microbiome and improved G:F in the first month of the feeding.