Proof of Concept for Enhanced Sugar Yields and Inhibitors Reduction from Aspen Biomass via Novel, Single-Step Nitrogen Explosive Decompression (NED 3.0) Pretreatment Method

Damaris Okafor (), Lisandra Rocha-Meneses, Vahur Rooni and Timo Kikas ()
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Damaris Okafor: Chair of Biosystems Engineering, Institute of Forestry and Engineering, Estonian University of Life Sciences, Fr. R. Kreutzwaldi 56, 51006 Tartu, Estonia
Lisandra Rocha-Meneses: Chair of Biosystems Engineering, Institute of Forestry and Engineering, Estonian University of Life Sciences, Fr. R. Kreutzwaldi 56, 51006 Tartu, Estonia
Vahur Rooni: Chair of Biosystems Engineering, Institute of Forestry and Engineering, Estonian University of Life Sciences, Fr. R. Kreutzwaldi 56, 51006 Tartu, Estonia
Timo Kikas: Chair of Biosystems Engineering, Institute of Forestry and Engineering, Estonian University of Life Sciences, Fr. R. Kreutzwaldi 56, 51006 Tartu, Estonia

Energies, 2025, vol. 18, issue 15, 1-37

Abstract: The transition to sustainable energy sources has intensified interest in lignocellulosic biomass (LCB) as a feedstock for second-generation biofuels. However, the inherent structural recalcitrance of LCB requires the utilization of an effective pretreatment to enhance enzymatic hydrolysis and subsequent fermentation yields. This manuscript presents a novel, single-step, and optimized nitrogen explosive decompression system (NED 3.0) designed to address the critical limitations of earlier NED versions by enabling the in situ removal of inhibitory compounds from biomass slurry and fermentation inefficiency at elevated temperatures, thereby reducing or eliminating the need for post-treatment detoxification. Aspen wood ( Populus tremula ) was pretreated by NED 3.0 at 200 °C, followed by enzymatic hydrolysis and fermentation. The analytical results confirmed substantial reductions in common fermentation inhibitors, such as acetic acid (up to 2.18 g/100 g dry biomass) and furfural (0.18 g/100 g dry biomass), during early filtrate recovery. Hydrolysate analysis revealed a glucose yield of 26.41 g/100 g dry biomass, corresponding to a hydrolysis efficiency of 41.3%. Fermentation yielded up to 8.05 g ethanol/100 g dry biomass and achieved a fermentation efficiency of 59.8%. Inhibitor concentrations in both hydrolysate and fermentation broth remained within tolerable limits, allowing for effective glucose release and sustained fermentation performance. Compared with earlier NED configurations, the optimized system improved sugar recovery and ethanol production. These findings confirm the operational advantages of NED 3.0, including reduced inhibitory stress, simplified process integration, and chemical-free operation, underscoring its potential for scalability in line with the EU Green Deal for bioethanol production from woody biomass.

Keywords: bioethanol; biomass; enzymatic hydrolysis; inhibitor reduction; single-step pretreatment; in situ detoxification; lignocellulose (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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