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Final Report: Fully utilizing biomass for biofuels and chemicals

EPA Grant Number: SU839320
Title: Fully utilizing biomass for biofuels and chemicals
Investigators: Wang, Donghai , Sun, Susan Xiuzhi , Benitez, Chris , Li, Jun , Brown, Nathaniel , Pradyawong, Sarocha , Xu, Youjie
Institution: Kansas State University
EPA Project Officer: Page, Angela
Phase: I
Project Period: February 1, 2018 through January 31, 2019
Project Amount: $14,964
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2017) RFA Text |  Recipients Lists
Research Category: P3 Awards , Sustainable and Healthy Communities , P3 Challenge Area - Air Quality

Objective:

 Available energy is essential to a continued healthy U.S. economy. Due to finite reserves, non-uniform distribution, and environmental issues with fossil fuels, we must explore eco-friendly and renewable energy to support sustainable economic development with respect to people, prosperity, and the planet. Bioethanol, a biofuel produced from lignocellulosic biomass, is one of the solutions. Major challenges to commercializing cellulosic biofuel are low fermentation efficiency and low ethanol concentration, and lack of technology to fully utilize byproducts from the bioconversion process such as lignin which has been underutilized. To overcome these technical barriers, we have designed a novel biorefining process to fully utilize each component of lignocellulosic biomass for biofuels and bio-chemicals production. The novel biorefining process involves green technologies such as hydrothermal and organosolv pretreatments to produce a cellulose-rich solid with good recovery of clean lignin as well as xylose remaining in the aqueous phase. Enzymatic saccharification and fermentation of cellulose-rich solids is critical to increase fermentable sugar and ethanol concentration to reduce ethanol distillation cost as minimum ethanol concentration of 40 g/L is required for economical distillation. Utilization of solvent-extracted lignin for value-added products such as bio-based adhesives would allow us to achieve integrated biorefining optimization.

The goal of this research was to develop a novel biorefining process to achieve high ethanol fermentation efficiency with high ethanol concentration and utilize lignin for bio- chemicals production with a focus on bio-adhesives. The specific objectives were: 1) to increase fermentable sugars (primarily glucose) yield through two-step pretreatment: hydrothermal and organosolv; 2) to achieve high-gravity ethanol fermentation and high ethanol titer through integrated novel processes; and 3) to develop protein-lignin polymers for bio-based adhesive application.

Summary/Accomplishments (Outputs/Outcomes):

During Phase I, we obtained the following major results:
1. Modified simultaneous saccharification and fermentation (nSSF) process was developed to enhance ethanol concentration and ethanol yield. Enzymatic hydrolysis of hydrothermal and organosolv treated samples improved glucose concentration from 35.8 g/L to 50.4 g/L as compared to hydrothermal treated only samples.
 
2. The mSSF achieved higher ethanol concentration of 58.5 g/L and ethanol yield of 83.5% as compared to the traditional SSF process (49.9 g/L and 71.1%) at the biomass loadings of 20% (w/v). The modified simultaneous saccharification and fermentation process also enabled higher ethanol concentration of 72.3 g/L at higher loadings of 30% (w/v) with yields of 70.0%. As compared to published high-gravity fermentation, ethanol concentration of 72.3 g/L achieved in this study was the highest in the lab-scale process, which proved that the proposed modified simultaneous saccharification and fermentation process was an effective process to increase ethanol titers without sacrificing ethanol yields.
 
3. Depolymerized lignin can be used for biogased adhesive application. Initial results showed the interaction of lignin and plant protein and lignin-protein cross-link enhanced the wet strength of soy protein adhesives. The wet adhesion strength of lignin-protein adhesive is 53% higher than that of soy protein adhesive. This result indicates lignin has a great potential to enhance adhesion properties of protein-based adhesives, which will be the focus of our Phase II study.

Conclusions:

The results in this project indicated high ethanol titer and ethanol yield as well as byproduct utilization through the proposed biorefining process could significantly accelerate the commercialization of cellulosic biofuel production, which provides a solid foundation for Phase II which will aim to develop lignin-plant protein-based adhesives to optimize the performance of soy protein and lignin adhesives.
 

Proposed Phase II Objectives and Strategies:

The overall goal of the phase II project is to develop a cost-effective, pollution-prevention, water- saving technology to produce bio-adhesives from lignin and plant protein based on the successful implementation of the Phase I results. The specific phase II objectives are: 1) to develop an innovative biomass pathway to depolymerize lignin into targeted molecules for biochemical applications using supercritical fluids; 2) to investigate chemical pathways of lignin-protein polymers at monomer, oligomer and polymer levels, 3) to develop and characterize lignin-protein adhesives with high water resistance. In this project, we will develop and demonstrate technologies to convert lignin produced in the integrated biorefinery to high value adhesives. Supercritical fluids with dispersed catalyst systems will be utilized to depolymerize lignin to phenolic intermediates which react with plant-derived proteins to produce lignin-protein based adhesives. The best chemical pathways of lignin-protein polymer will be identified. The lignin and protein will be modified to enhance the chemical reactions and adhesive strength.


Journal Articles on this Report : 2 Displayed | Download in RIS Format

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Other project views: All 2 publications 2 publications in selected types All 2 journal articles
Publications
Type Citation Project Document Sources
Journal Article Pradyawong S, Qi G, Li N, Sun XS, Wang D. Adhesion properties of soy protein adhesives enhanced by biomass lignin. International Journal of Adhesion and Adhesives 2017;75:66-73. SU839320 (Final)
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    • Journal Article Xu Y, Li J, Zhang M, Wang D. Modified simultaneous saccharification and fermentation to enhance bioethanol titers and yields. Fuel 2018;215:647-654. SU839320 (Final)
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    • Supplemental Keywords:

    waste to fuel, environmental education, bio-adhesives

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