Rheology of corn stover slurries at high solids concentrations – Effects of saccharification and particle size

Viamajala, Sridhar; McMillan, James D.; Schell, Daniel J.; Elander, Richard T.

doi:10.1016/j.biortech.2008.06.070

Cited by 173 publications

(150 citation statements)

References 28 publications

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“…Wiman et al [115] found that decreasing particle size by milling increased power law index to 7.1 from 5.0. Similar results were reported by Viamajala et al [117] where the power law index was increased from 3.0 to 4.0 as the particle size was reduced from 20 to 80 mesh. For wood pulp fibers, the power law index is reported in the narrower range of 2.3-3.6 [118].…”

Section: Rheology Of Lignocellulosic Biomasssupporting

confidence: 79%

“…For instance, at concentration of 20% (w/w), the volume fraction of dilute acid pretreated corn stover is approximately 40% [98]. Contrary to other studies, Viamajala et al [117] found that yield stress and viscosity reached a maximum point beginning from biomass concentration of 20% (w/w) depending on particle size and pre-treatment. At that point, the slurry was observed to be a wet granular material with little or no free water.…”

Section: Rheology Of Lignocellulosic Biomasscontrasting

confidence: 39%

“…According to data published by Ehrhardt et al [119], power law index decreased from 4.4 to 3.7 as pretreatment severity was increased. An opposite trend can be observed from data published by Viamajala et al [117], where pretreated samples had higher power law indices than untreated samples. Wiman et al [115] found that decreasing particle size by milling increased power law index to 7.1 from 5.0.…”

Section: Rheology Of Lignocellulosic Biomasscontrasting

confidence: 34%

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Biomass processing into ethanol: pretreatment, enzymatic hydrolysis, fermentation, rheology, and mixing

Volynets

Ein‐Mozaffari

Dahman

2016

Green Processing and Synthesis

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Alternate energy resources need to be developed to amend for depleting fossil fuel reserves. Lignocellulosic biomass is a globally available renewable feedstock that contains a rich sugar platform that can be converted into bioethanol through appropriate processing. The key steps of the process, pretreatment, enzymatic hydrolysis, and fermentation, have undergone considerable amount of research and development over the past decades nearing the process to commercialization. In order for the commercialization to be successful, the process needs to be operated at high dry matter content of biomass, especially in the enzymatic hydrolysis stage that influences ethanol concentration in the final fermentation broth. Biomass becomes a thick paste with challenging rheology for mixing to be effective. As the biomass consistency increases, yield stress increases which limits efficiency of mixing with conventional stirred tanks. The purpose of this review is to provide features and perspectives on processing of biomass into ethanol. Emphasis is placed on rheology and mixing of biomass in the enzymatic hydrolysis step as one of the forefront issues in the field.

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Section: Rheology Of Lignocellulosic Biomasssupporting

confidence: 79%

Section: Rheology Of Lignocellulosic Biomasscontrasting

confidence: 39%

Section: Rheology Of Lignocellulosic Biomasscontrasting

confidence: 34%

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Biomass processing into ethanol: pretreatment, enzymatic hydrolysis, fermentation, rheology, and mixing

Volynets

Ein‐Mozaffari

Dahman

2016

Green Processing and Synthesis

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“…The concentrations of both accumulated sugars and end products at an initial cellulose concentration of 100 g liter Ϫ1 were lower than those at an initial cellulose concentration of 80 g liter Ϫ1 , indicating that low bioconversion yields under 100 g liter Ϫ1 were not due to sugar accumulation and end product inhibition but mainly due to the inhibition of cellulose hydrolysis. In addition, under this high cellulose concentration, slurry rheological properties might undergo dynamic and dramatic changes as the conversion proceeded (30), and then mass transfer limitation became a main factor responsible for the low utilization rate (31), which might also contribute to the decrease in fermentation following the increase in initial cellulose concentrations from 80 g liter Ϫ1 to 100 g liter Ϫ1 in this study. The inhibitory effect of high cellulose concentrations suggested that cellulose concentrations for thermophilic fermentation by the cocultures LQRI and X514 should be controlled at levels not higher than 80 g liter Ϫ1 , which could be readily achieved by cyclic fedbatch operations (32).…”

Section: Discussionmentioning

confidence: 77%

Continuous Cellulosic Bioethanol Fermentation by Cyclic Fed-Batch Cocultivation

Jiang

et al. 2013

Appl Environ Microbiol

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f Cocultivation of cellulolytic and saccharolytic microbial populations is a promising strategy to improve bioethanol production from the fermentation of recalcitrant cellulosic materials. Earlier studies have demonstrated the effectiveness of cocultivation in enhancing ethanolic fermentation of cellulose in batch fermentation. To further enhance process efficiency, a semicontinuous cyclic fed-batch fermentor configuration was evaluated for its potential in enhancing the efficiency of cellulose fermentation using cocultivation. Cocultures of cellulolytic Clostridium thermocellum LQRI and saccharolytic Thermoanaerobacter pseudethanolicus strain X514 were tested in the semicontinuous fermentor as a model system. Initial cellulose concentration and pH were identified as the key process parameters controlling cellulose fermentation performance in the fixed-volume cyclic fed-batch coculture system. At an initial cellulose concentration of 40 g liter ؊1 , the concentration of ethanol produced with pH control was 4.5-fold higher than that without pH control. It was also found that efficient cellulosic bioethanol production by cocultivation was sustained in the semicontinuous configuration, with bioethanol production reaching 474 mM in 96 h with an initial cellulose concentration of 80 g liter ؊1 and pH controlled at 6.5 to 6.8. These results suggested the advantages of the cyclic fed-batch process for cellulosic bioethanol fermentation by the cocultures. Bioethanol remains an important renewable energy alternative to petroleum-based liquid transportation fuels (1). While bioethanol derived from food crops such as corn and sugarcane has dominated the current biofuel market, recent efforts have focused on the conversion of lignocellulosic biomass to bioethanol, i.e., cellulosic bioethanol, which is considered to be socioeconomically and environmentally more sustainable (2, 3).However, the recalcitrance of cellulosic feedstock to bioconversion has posed a major challenge to the development of effective processes for cellulosic bioethanol, which typically include separate steps of enzymatic cellulose hydrolysis and microbial ethanologenic fermentation. One strategy to improve the cellulose utilization efficiency and then the ethanol production rate is the development of microbial consortia capable of simultaneously carrying out both cellulose hydrolysis and ethanologenic fermentation, representing an implementation of the consolidated bioprocessing (CBP) concept (4). Indeed, it has been demonstrated in earlier studies that cocultivation of cellulolytic and saccharolytic microbial populations could be successfully developed in batch cultures to improve cellulose utilization and ethanol production (5-7). Subsequent studies further identified metabolic mutualism, such as the supply of growth factors and utilization of excess metabolites, as the mechanism contributing to these improvements in ethanolic cellulose fermentation by cocultivation (5,8,9), further supporting the potential of cocultivation for enhancing cellulosic bi...

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“…However, solids loadings higher than 10% w/w are required to obtain cost-effective concentrations of sugars (Wingren et al, 2003). Due to the high water-holding capacity of solids, the reaction medium cannot be efficiently sheared and mixed at solids loadings higher than 10% w/w (Viamajala et al, 2009). In addition, conversion at increasing solids loadings exhibits a general decreasing trend (Kristensen et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Continuous and Semicontinuous Reaction Systems for High-Solids Enzymatic Hydrolysis of Lignocellulosics

Gonzalez‐Quiroga

Bula

Padilla

et al. 2015

Braz. J. Chem. Eng.

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-An attractive operation strategy for the enzymatic hydrolysis of lignocellulosics results from dividing the process into three stages with complementary goals: continuous enzyme adsorption at low-solids loading (5% w/w) with recycling of the liquid phase; continuous liquefaction at high-solids content (up to 20% w/w); and, finally, continuous or semicontinuous hydrolysis with supplementation of fresh enzymes. This paper presents a detailed modeling and simulation framework for the aforementioned operation strategies. The limiting micromixing situations of macrofluid and microfluid are used to predict conversions. The adsorption and liquefaction stages are modeled as a continuous stirred tank and a plug flow reactor, respectively. Two alternatives for the third stage are studied: a train of five cascading stirred tanks and a battery of batch reactors in parallel. Simulation results show that glucose concentrations greater than 100 g L -1 could be reached with both of the alternatives for the third stage.

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Rheology of corn stover slurries at high solids concentrations – Effects of saccharification and particle size

Cited by 173 publications

References 28 publications

Biomass processing into ethanol: pretreatment, enzymatic hydrolysis, fermentation, rheology, and mixing

Biomass processing into ethanol: pretreatment, enzymatic hydrolysis, fermentation, rheology, and mixing

Continuous Cellulosic Bioethanol Fermentation by Cyclic Fed-Batch Cocultivation

Continuous and Semicontinuous Reaction Systems for High-Solids Enzymatic Hydrolysis of Lignocellulosics

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