Sustainability metrics of pretreatment processes in a waste derived lignocellulosic biomass biorefinery

Islam, Khairul; Wang, Huaimin; Rehman, Shazia; Dong, Chengyu; Hsu, Hsien‐Yi; Lin, Carol Sze Ki; Leu, Shao‐Yuan

doi:10.1016/j.biortech.2019.122558

Cited by 115 publications

(53 citation statements)

References 128 publications

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“…Simultaneous and efficient utilization of hexoses and pentoses derived from lignocellulosic biomass is a critical bottleneck to the complete utilization of substrates [7]. Lignocellulosic hydrolysates are composed of 50-70% cellodextrins and glucose, 20-30% xylose, 0-25% lignin, some extractives (such as terpenes alkaloids, fats, and waxes), and reaction by-products, of which the types and proportion of sugars vary significantly among biomass and pretreatment methods [8,9]. Current biorefinery processes have successfully applied hexoses for lactic acid fermentation [10], but utilization of pentoses is still challenging due to the metabolic regulation of carbon catabolite repression (CCR) [11].…”

mentioning

confidence: 99%

Dynamic simulation of continuous mixed sugar fermentation with increasing cell retention time for lactic acid production using Enterococcus mundtii QU 25

Wang

Chan

Abdel-Rahman

et al. 2020

Biotechnol Biofuels

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Background: The simultaneous and effective conversion of both pentose and hexose in fermentation is a critical and challenging task toward the lignocellulosic economy. This study aims to investigate the feasibility of an innovative cofermentation process featuring with a cell recycling unit (CF/CR) for mixed sugar utilization. A l-lactic acid-producing strain Enterococcus mundtii QU 25 was applied in the continuous fermentation process, and the mixed sugars were utilized at different productivities after the flowing conditions were changed. A mathematical model was constructed with the experiments to optimize the biological process and clarify the cell metabolism through kinetics analysis. The structured model, kinetic parameters, and achievement of the fermentation strategy shall provide new insights toward whole sugar fermentation via real-time monitoring for process control and optimization. Results: Significant carbon catabolite repression in co-fermentation using a glucose/xylose mixture was overcome by replacing glucose with cellobiose, and the ratio of consumed pentose to consumed hexose increased significantly from 0.096 to 0.461 by mass. An outstanding product concentration of 65.2 g L −1 and productivity of 13.03 g L −1 h −1 were achieved with 50 g L −1 cellobiose and 30 g L −1 xylose at an optimized dilution rate of 0.2 h −1 , and the cell retention time gradually increased. Among the total lactic acid production, xylose contributed to more than 34% of the mixed sugars, which was close to the related contents in agricultural residuals. The model successfully simulated the transition of sugar consumption, cell growth, and lactic acid production among the batch, continuous process, and CF/CR systems. Conclusion: Cell retention time played a critical role in balancing pentose and hexose consumption, cell decay, and lactic acid production in the CF/CR process. With increasing cell concentration, consumption of mixed sugars increased with the productivity of the final product; hence, the impact of substrate inhibition was reduced. With the validated parameters, the model showed the highest accuracy simulating the CF/CR process, and significantly longer cell retention times compared to hydraulic retention time were tested.

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mentioning

confidence: 99%

Dynamic simulation of continuous mixed sugar fermentation with increasing cell retention time for lactic acid production using Enterococcus mundtii QU 25

Wang

Chan

Abdel-Rahman

et al. 2020

Biotechnol Biofuels

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“…To better visualize the potential applications of the long CRT operation, the dynamic model was simpli ed to steady state expressions as the numerical strategy used in Leu et al [27]. The expressions were derived by eliminating the accumulation terms (i.e., dX/dt and dS/dt) in Equations (7) and (8), and followed by a series of algebraic operations as presented in supplementary information (Equations (S1) to (S12)). The sugar and cell concentrations as functions of the key control parameters are presented in the following equations: (see Equations 10 and 11 in the Supplementary FIles)…”

Section: Importance Of Cell Retention Time (Crt)mentioning

confidence: 99%

“…Simultaneous and e cient utilization of hexoses and pentoses derived from lignocellulosic biomass is a critical bottleneck to the complete utilization of substrates [7]. Lignocellulosic hydrolysates are composed of 50-70% cellodextrins and glucose, 20-30% xylose, 0-25% lignin, some extractives (such as terpenes alkaloids, fats, and waxes), and reaction by-products, of which the types and proportion of sugars vary signi cantly among biomass and pretreatment methods [8,9]. Current biore nery processes have successfully applied hexoses for lactic acid fermentation [10], but utilization of pentoses is still challenging due to the metabolic regulation of carbon catabolite repression (CCR) [11].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Simulation of Continuous Mixed Sugar Fermentation with Increasing Cell Retention Time for Lactic Acid Production using Enterococcus mundtii QU 25

Wang

Chan

Abdel-Rahman

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Background: The simultaneous and effective conversion of both pentose and hexose in fermentation is a critical and challenging task towards the lignocellulosic economy. This study aims to investigate the feasibility of an innovative co-fermentation process featuring with a cell recycling unit (CF/CR) for mixed sugar utilization. A l-lactic acid producing strain Enterococcus mundtii QU 25, was applied in the continuous fermentation process, and the mixed sugars were utilized at different productivities after the flowing conditions were changed. A numerical platform was constructed with the experiments to optimize the biological process and clarify the cell metabolism through kinetics analysis. The structured model, kinetic parameters, and achievement of the fermentation strategy shall provide new insights towards whole sugar fermentation via real-time monitoring for process control and optimization. Results: Significant carbon catabolite repression in co-fermentation using a glucose/xylose mixture was overcome by replacing glucose with cellobiose, and the ratio of consumed pentose to consumed hexose increased significantly from 0.096 to 0.461 by mass. An outstanding product concentration of 65.2 g·L-1 and productivity of 13.03 g·L-1·h-1 were achieved with 50 g·L-1 cellobiose and 30 g·L-1 xylose at an optimized dilution rate of 0.2 h-1, and the cell retention time gradually increased. Among the total lactic acid production, xylose contributed to more than 34% of the mixed sugars, which was close to the related contents in agricultural residuals. The model successfully simulated the transition of sugar consumption, cell growth, and lactic acid production among the batch, continuous process, and CF/CR systems. Conclusion: Cell retention time played a critical role in balancing pentose and hexose consumption, cell decay, and lactic acid production in the CF/CR process. With increasing cell concentration, consumption of mixed sugars increased with the productivity of the final product; hence, the impact of substrate inhibition was reduced. With the validated parameters, the model showed the highest accuracy simulating the CF/CR process, and significantly longer cell retention times compared to hydraulic retention time were tested.

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“…A secondary experiment revealed that the cell lipid production increase from 5% to 49.5% in the presence of the three different PPCPs. Islam et al (2019) studied the sustainability metrics and operational risk of various pretreatment techniques used during urbanization. They proposed green indexes which include chemical recyclability, fractionation outputs, safety factors, and operational profile.…”

Section: Microalgaementioning

confidence: 99%

Bioenergy from biofuel residues and waste

Sheehan

Murray

et al. 2020

Water Environment Research

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Sustainability metrics of pretreatment processes in a waste derived lignocellulosic biomass biorefinery

Cited by 115 publications

References 128 publications

Dynamic simulation of continuous mixed sugar fermentation with increasing cell retention time for lactic acid production using Enterococcus mundtii QU 25

Dynamic simulation of continuous mixed sugar fermentation with increasing cell retention time for lactic acid production using Enterococcus mundtii QU 25

Dynamic Simulation of Continuous Mixed Sugar Fermentation with Increasing Cell Retention Time for Lactic Acid Production using Enterococcus mundtii QU 25

Bioenergy from biofuel residues and waste

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