Enhancement of Ethanol Production from Napiergrass (<i>Pennisetum purpureum</i> Schumach) by a Low-Moisture Anhydrous Ammonia Pretreatment

Abstract

Napiegrass (Pennisetum purpureum Schumach) was treated with a low-moisture anhydrous ammonia (LMAA) pretreatment by adding an equal weight of water and keeping it under atmospheric ammonia gas at room temperature for four weeks. After the removal of ammonia and washing with water, a simultaneous saccharification and fermentation (SSF) was conducted for the LMAA-pretreated napiergrass (1.33 g) in a buffer solution (8 mL) using a mixture of a cellulase (80 mg) and a xylanase (53 mg) as well as the cell suspension (0.16 mL) of Saccharomyces cerevisiae. Ethanol and xylose resulted in 91.2% and 62.9% yields, respectively. The SSF process was scaled up using LMAA-pretreated napiergrass (100.0 g) to give ethanol (77.2%) and xylose (52.8%). After the removal of ethanol, the pentose fermentation of the SSF solution (40 mL), which contained 1.00 g of xylose, using cell suspension of Escherichia coli KO11 (70 mL) gave 86.3% yield of ethanol. Total ethanol yield reached 68.9% based on xylan (21.4 wt%) and glucan (39.7 wt%) of the LMAA-pretreated napiergrass.

Modelling and optimization of xylose and glucose production from napier grass using hybrid pre-treatment techniques

“…The experimental validation gave 15.1 gL À1 and 2.4 gL À1 of xylose and glucose yields respectively, thus a 6:1 xylose to glucose concentration ratio. These results showed an improvement on an earlier report by Yasuda et al [22], where 32 mg L À1 and 150 mg L 1 glucose and xylose production respectively was observed when Napier grass was treated with low moisture anhydrous ammonia (LMAA). The observed ratios of xylose to glucose were similar for both optimized hybrid pre-treatments.…”

“…This low production of fermentable sugars can be attributed to the short pre-treatment duration applied in this study (maximum 3 h) and low alkaline concentrations (maximum 5% NaOH). These findings differ from the report of Liong et al [21] who obtained a glucose yield of 7.3 gL À1 from Napier grass pretreated with 7% NaOH for 4 h at 35 C. Yasuda et al [22] observed 807 mg xylose yield when 100 g Napier grass was treated with low-moisture anhydrous ammonia (LMAA) at room temperature for 4 weeks. Wongwatanapaiboon et al [20] reported 4.14 gL À1 total reducing sugar yield when Napier grass was treated with 7.5% alkaline peroxide at 35 C for 24 h. According to Moiser et al [23], alkaline pre-treatment yields high sugar concentrations under long resident time (measured in days) at ambient temperature.…”

Variation of Morpho-Agronomic and Biomass Quality Traits in Elephant Grass for Energy Purposes According to Nitrogen Levels

“…Recently, because of its high biomass production potential, another use for elephant grass has been proposed: its transformation into firewood [1], which may replace the wood extracted in a predatory manner from native forests, thus preventing environmental damage such as ravaging of forests, erosion, siltation, and death of several rivers. The biomass has gained great attention as a new source of sustainable energy alternative to petroleum-based fuels [2], in addition to also working in the carbon sequestration [3].…”

Fuelization of Italian Ryegrass and Napier Grass through a Biological Treatment and Photocatalytic Reforming

“…The LMAA pretreatment was performed by modifying the Kim method where LMAA pretreatment was performed at 80˚C for 86 h [13]. In our LMAA-pretreatment [14], the moist powdered lignocellulose was kept under NH 3 gas atmosphere at room temperature for four weeks. After the treatment, the NH 3 was removed with an evaporator.…”

“…The SSF was performed using a mixture of cellulase and xylanase as well as S. cerevisiae under the conditions optimized for Napier grass [14] as follows. The LMAA-and AL-pretreated Italian ryegrass and Napier grass (3.0 g) were dispersed in an acetate buffer solution (10 mL, pH 5.0, 0.1 M).…”