Optimization of high solids fed-batch saccharification of sugarcane bagasse based on system viscosity changes

Liu, Yunyun; Xu, Jingliang; Zhang, Yu; Yuan, Zhenhong; Xie, Jun

doi:10.1016/j.jbiotec.2015.06.422

Cited by 56 publications

(38 citation statements)

References 25 publications

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“…Enzymolysis at high solid loading can contribute to gaining high sugars concentration while cutting the cost of a lignocellulose biorefinery due to fewer devices, less energy and water consumption. However, high solid loading may definitely reduce the enzymolysis efficiency because of high viscosity, poor mass transfer and lower contact between biomass and cellulase . Based on the superiorities of AHP‐ILW pretreatment, further study of enzymolysis with high solid loading is essential.…”

Section: Resultssupporting

confidence: 82%

“…It was speculated that fermentation inhibitors such as various organic acids accumulated gradually during the process of SScF and the high viscosity could also cause loss of efficiency. An effective method for high solids fed‐batch enzymolysis of sugarcane bagasse based on system viscosity changes has been developed and could alleviate the high viscosity problem . Therefore, the optimization of SScF processes such as with fed‐batch schemes at high solid loadings is worth further study.…”

Section: Resultsmentioning

confidence: 99%

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Improved enzymatic hydrolysis and ethanol production by combined alkaline peroxide and ionic liquid‐water mixtures pretreatment of rice straw

Hong

Wang²,

Zhu³

et al. 2019

J of Chemical Tech & Biotech

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BACKGROUND Rice straw (RS), one of the most plentiful lignocellulosic wastes worldwide, has been considered a potential candidate to produce bioethanol. The object of this work was to develop an efficient and feasible pretreatment process for RS with alkaline peroxide combined with ionic liquid (IL)–water mixtures, reveal the mechanism, and achieve biomass valorization. RESULTS Alkaline peroxide pretreatment under mild conditions combined with IL–water mixtures pretreatment at a water content of 30 wt% was established, leading to a maximum lignin removal of 63.8% with an enzymolysis efficiency of 92.1% and a simultaneous saccharification and co‐fermentation efficiency of 91.0%. Furthermore, the recycled IL also showed good performance with the established pretreatment process, resulting in 251.6 g L−1 of reducing sugar and 91.9 g L−1 ethanol at high solid loading. The alkaline peroxide pretreatment enhanced lignin extraction and disrupted the RS structure to facilitate the dissolution of amorphous components by the IL–water mixtures. CONCLUSION A simple and efficient pretreatment was successfully established. The IL was successfully recycled for further pretreatments, and high concentrations of reducing sugars and ethanol were achieved using the pretreated RS. The effectiveness of the pretreatment process suggested potential application in future biorefineries. © 2018 Society of Chemical Industry

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Improved enzymatic hydrolysis and ethanol production by combined alkaline peroxide and ionic liquid‐water mixtures pretreatment of rice straw

Hong

Wang²,

Zhu³

et al. 2019

J of Chemical Tech & Biotech

View full text Add to dashboard Cite

show abstract

“…Liu et al [30], for example, reported laboratory (small scale 250 mL) studies on batch-fed saccharification of sugarcane bagasse, and achieved 135 g/L glucose (13 % w/v) using cellulase loadings of 8.5 FPU/g substrate. Their pretreatment required high levels of hot alkali (equivalent to 200 kg NaOH per tonne bagasse).…”

Section: Resultsmentioning

confidence: 99%

Comparison of saccharification and fermentation of steam exploded rice straw and rice husk

Wood

Cao

Tran

et al. 2016

Biotechnol Biofuels

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BackgroundRice cultivation produces two waste streams, straw and husk, which could be exploited more effectively. Chemical pretreatment studies using rice residues have largely focussed on straw exploitation alone, and often at low substrate concentrations. Moreover, it is currently not known how rice husk, the more recalcitrant residue, responds to steam explosion without the addition of chemicals.ResultsThe aim of this study has been to systematically compare the effects of steam explosion severity on the enzymatic saccharification and simultaneous saccharification and fermentation of rice straw and husk produced from a variety widely grown in Vietnam (Oryza sativa, cv. KhangDan18). Rice straw and husk were steam exploded (180–230 °C for 10 min) into hot water and washed to remove fermentation inhibitors. In both cases, pretreatment at 210 °C and above removed most of the noncellulosic sugars. Prolonged saccharification at high cellulase doses showed that rice straw could be saccharified most effectively after steam explosion at 210 °C for 10 min. In contrast, rice husk required more severe pretreatment conditions (220 °C for 10 min), and achieved a much lower yield (75 %), even at optimal conditions. Rice husk also required a higher cellulase dose for optimal saccharification (10 instead of 6 FPU/g DM). Hemicellulase addition failed to improve saccharification. Small pilot scale saccharification at 20 % (w/v) substrate loading in a 10 L high torque bioreactor resulted in similarly high glucose yields for straw (reaching 9 % w/v), but much less for husk. Simultaneous saccharification and fermentation under optimal pretreatment and saccharification conditions showed similar trends, but the ethanol yield from the rice husk was less than 40 % of the theoretical yield.ConclusionsDespite having similar carbohydrate compositions, pretreated rice husk is much less amenable to saccharification than pretreated rice straw. This is likely to attenuate its use as a biorefinery feedstock unless improvements can be made either in the feedstock through breeding and/or modern biotechnology, or in the pretreatment through the employment of improved or alternative technologies. Physiological differences in the overall chemistry or structure may provide clues to the nature of lignocellulosic recalcitrance.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0599-6) contains supplementary material, which is available to authorized users.

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“…Furthermore, after a certain level of hydrolysis is achieved, a pulsed feed of new pretreated biomass can be administered to the reactor. Such a fed-batch process can be effective only when care is taken that the new batch of hygroscopic biomass does not create enzyme mass transfer issues (Liu et al, 2015). With phase angle data from our rheological testing, along with further optimization, it will be possible to identify a suitable time for administering the new batch.…”

Section: Perspectivementioning

confidence: 99%

In Situ Rheological Method to Evaluate Feedstock Physical Properties Throughout Enzymatic Deconstruction

et al. 2018

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Feedstock physical properties determine not only downstream flow behavior, but also downstream process yields. Enzymatic treatment of pretreated feedstocks is greatly dependent on upstream feedstock physical properties and choice of pre-processing Technologies. Currently available enzyme assays have been developed to study biomass slurries at low concentrations of ≤1% w/w. At commercially relevant biomass concentrations of ≥15% w/w, pretreated feedstocks have sludge-like properties, where low free water restricts movement of unattached enzymes. This work is an account of the various steps taken to develop a method that helps identify the time needed for solid-like biomass slurries transition into liquid-like states during enzymatic hydrolysis. A pre-processing technology that enables feedstocks in achieving this transition sooner will greatly benefit enzyme kinetics and thereby overall process economics. Through this in situ rheological properties determining method, we compared a model feedstock, Avicel ® PH101 cellulose, with acid pretreated corn stover. Novozymes Cellic ® CTec2 (80 mg protein/g glucan) can reduce 25% (w/w) Avicel from solid-like to liquid-like state in 5.5 h, as the phase angles rise beyond 45 • at this time. The same slurry needed 5.3 h to achieve liquid-like state with Megazyme endoglucanase (40 mg protein/g glucan). After 10.8 h, CTec2 slurry reached a phase angle of 89 • or complete liquid-like state but Megazyme slurry peaked only to 64.7 • , possibly due to inhibition by cello-oligomers. Acid pretreated corn stover at 30% (w/w) with a CTec2 protein loading of 80 mg/g glucan exhibited a solid-like to liquid-like transition at 37.8 h, which reflects the combined inhibition of low water activity and presence of lignin. The acid pretreated slurry also never achieved complete liquid-like state due to the presence of biomass residue. This method is applicable in several scenarios comparing varying combinations of pre-processing technologies, feedstock types, pretreatment chemistries, and enzymes. Using this method, we can generate a process chain with optimal flow behavior at commercially-relevant conditions.

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Optimization of high solids fed-batch saccharification of sugarcane bagasse based on system viscosity changes

Cited by 56 publications

References 25 publications

Improved enzymatic hydrolysis and ethanol production by combined alkaline peroxide and ionic liquid‐water mixtures pretreatment of rice straw

Improved enzymatic hydrolysis and ethanol production by combined alkaline peroxide and ionic liquid‐water mixtures pretreatment of rice straw

Comparison of saccharification and fermentation of steam exploded rice straw and rice husk

In Situ Rheological Method to Evaluate Feedstock Physical Properties Throughout Enzymatic Deconstruction

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