Fundamentals of Aqueous Pretreatment of Biomass

Mosier, Nathan S.

doi:10.1002/9780470975831.ch7

Cited by 23 publications

(11 citation statements)

References 59 publications

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“…Liquid hot water pretreatment is also termed as hot water pretreatment, hot compressed water pretreatment, and hydrothermal pretreatment. Since the pretreatment does not use any other chemicals, it is an environmentally friendly method with low operation and capital costs compared to chemical pretreatment [ 34 ]. However, hot water pretreatment requires 20–50 °C higher temperatures and 5–15 min longer residence times compared to dilute acid pretreatment to gain the same cellulose conversion yields.…”

Section: One-step Pretreatmentmentioning

confidence: 99%

Promise of combined hydrothermal/chemical and mechanical refining for pretreatment of woody and herbaceous biomass

Kim

Dien

2016

Biotechnol Biofuels

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Production of advanced biofuels from woody and herbaceous feedstocks is moving into commercialization. Biomass needs to be pretreated to overcome the physicochemical properties of biomass that hinder enzyme accessibility, impeding the conversion of the plant cell walls to fermentable sugars. Pretreatment also remains one of the most costly unit operations in the process and among the most critical because it is the source of chemicals that inhibit enzymes and microorganisms and largely determines enzyme loading and sugar yields. Pretreatments are categorized into hydrothermal (aqueous)/chemical, physical, and biological pretreatments, and the mechanistic details of which are briefly outlined in this review. To leverage the synergistic effects of different pretreatment methods, conducting two or more pretreatments consecutively has gained attention. Especially, combining hydrothermal/chemical pretreatment and mechanical refining, a type of physical pretreatment, has the potential to be applied to an industrial plant. Here, the effects of the combined pretreatment (combined hydrothermal/chemical pretreatment and mechanical refining) on energy consumption, physical structure, sugar yields, and enzyme dosage are summarized.

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Section: One-step Pretreatmentmentioning

confidence: 99%

Promise of combined hydrothermal/chemical and mechanical refining for pretreatment of woody and herbaceous biomass

Kim

Dien

2016

Biotechnol Biofuels

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“…Formic acid and acetic acid are released from dissociation of hemicellulose/cellulose/ lignin inter-polymeric linkages. 58,59 And oligomers can directly degrade into various as yet not fully characterized compounds. 18,60 Lignin is believed to depolymerize and form micelles via both homolytic and acidolytic cleavage into low molecular weight lignin globules.…”

Section: Fundamentals Of Hydrothermal Processing Effects On Biomassmentioning

confidence: 99%

Strengths, challenges, and opportunities for hydrothermal pretreatment in lignocellulosic biorefineries

Yang

Tao

Wyman

2017

Biofuels Bioprod Bioref

117

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Pretreatment prior to or during biological conversion is required to achieve high sugar yields essential to economic production of fuels and chemicals from low cost, abundant lignocellulosic biomass. Aqueous thermochemical pretreatments achieve this performance objective from pretreatment coupled with subsequent enzymatic hydrolysis, but chemical pretreatment can also suffer from additional costs for exotic materials of construction, the need to recover or neutralize the chemicals, introduction of compounds that inhibit downstream operations, and waste disposal, as well as for the chemicals themselves. The simplicity of hydrothermal pretreatment with just hot water offers the potential to greatly improve the cost of the entire conversion process if sugar degradation during pretreatment, production of un-fermentable oligomers, and the amount of expensive enzymes needed to obtain satisfactory yields from hydrothermally pretreated solids can be reduced. Biorefi nery economics would also benefi t if value could be generated from lignin and other components that are currently fated to be burned for power. However, achieving these goals will no doubt require development of advanced hydrothermal pretreatment confi gurations. For example, passing water through a stationary bed of lignocellulosic biomass in a fl owthrough confi guration achieves very high yields of hemicellulose sugars, removes more than 75% of the lignin for potential valorization, and improves sugar release from the pretreated solids with lower enzyme loadings. Unfortunately, the large quantities of water needed to achieve this performance result in very dilute sugars, high energy costs for pretreatment and product recover, and large amounts of oligomers. Thus, improving our understanding of 126

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“…As is common with acid-based pretreatments, increased pretreatment severity successively increased the solubilization of hemicellulose from the plant cell wall matrix, thus enriching the pretreated solids in cellulose and lignin for both bagasse and CLM [ 30 , 33 ]. Within the evaluated conditions, the highest combined sugar yield for bagasse was obtained at intermediate severity (Log R 0 = 4.22), amounting to 55.3 kg sugar/100 kg RDM (77% of the theoretical maximum).…”

Section: Resultsmentioning

confidence: 99%

“…During the pretreatment process, there is selective fractionation of hemicellulose, partial cleavage of lignin–carbohydrate complex ester linkages and increased substrate accessibility toward hydrolytic enzymes [ 29 – 32 ]. Advantages of StEx pretreatment for integration in sugar mill operations include the use of water as a green solvent, relatively low capital investment, moderate energy requirements and the ability to use high-moisture content biomass (such as bagasse) [ 31 , 33 ]. However, due to pretreatment severities required for obtaining high cellulose digestibility, StEx generates hemicellulose and cellulose-derived degradation products that are inhibitory to downstream enzymatic hydrolysis and fermentation [ 34 ].…”

Section: Introductionmentioning

confidence: 99%

Ethanol production potential from AFEX™ and steam-exploded sugarcane residues for sugarcane biorefineries

Mokomele

Sousa

Balan

et al. 2018

Biotechnol Biofuels

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BackgroundExpanding biofuel markets are challenged by the need to meet future biofuel demands and mitigate greenhouse gas emissions, while using domestically available feedstock sustainably. In the context of the sugar industry, exploiting under-utilized cane leaf matter (CLM) in addition to surplus sugarcane bagasse as supplementary feedstock for second-generation ethanol production has the potential to improve bioenergy yields per unit land. In this study, the ethanol yields and processing bottlenecks of ammonia fibre expansion (AFEX™) and steam explosion (StEx) as adopted technologies for pretreating sugarcane bagasse and CLM were experimentally measured and compared for the first time.ResultsEthanol yields between 249 and 256 kg Mg−1 raw dry biomass (RDM) were obtained with AFEX™-pretreated sugarcane bagasse and CLM after high solids loading enzymatic hydrolysis and fermentation. In contrast, StEx-pretreated sugarcane bagasse and CLM resulted in substantially lower ethanol yields that ranged between 162 and 203 kg Mg−1 RDM. The ethanol yields from StEx-treated sugarcane residues were limited by the aggregated effect of sugar degradation during pretreatment, enzyme inhibition during enzymatic hydrolysis and microbial inhibition of S. cerevisiae 424A (LNH-ST) during fermentation. However, relatively high enzyme dosages (> 20 mg g−1 glucan) were required irrespective of pretreatment method to reach 75% carbohydrate conversion, even when optimal combinations of Cellic® CTec3, Cellic® HTec3 and Pectinex Ultra-SP were used. Ethanol yields per hectare sugarcane cultivation area were estimated at 4496 and 3416 L ha−1 for biorefineries using AFEX™- or StEx-treated sugarcane residues, respectively.ConclusionsAFEX™ proved to be a more effective pretreatment method for sugarcane residues relative to StEx due to the higher fermentable sugar recovery and enzymatic hydrolysate fermentability after high solids loading enzymatic hydrolysis and fermentation by S. cerevisiae 424A (LNH-ST). The identification of auxiliary enzyme activities, adequate process integration and the use of robust xylose-fermenting ethanologens were identified as opportunities to further improve ethanol yields from AFEX™- and StEx-treated sugarcane residues.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1130-z) contains supplementary material, which is available to authorized users.

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Fundamentals of Aqueous Pretreatment of Biomass

Cited by 23 publications

References 59 publications

Promise of combined hydrothermal/chemical and mechanical refining for pretreatment of woody and herbaceous biomass

Promise of combined hydrothermal/chemical and mechanical refining for pretreatment of woody and herbaceous biomass

Strengths, challenges, and opportunities for hydrothermal pretreatment in lignocellulosic biorefineries

Ethanol production potential from AFEX™ and steam-exploded sugarcane residues for sugarcane biorefineries

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