Lignocellulosic ethanol: From science to industry

Viikari, Liisa; Vehmaanperä, Jari; Koivula, Anu

doi:10.1016/j.biombioe.2012.05.008

Cited by 234 publications

(127 citation statements)

References 67 publications

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“…With high ethanol yields, final ethanol concentrations for cost-efficient downstream processing can be reached with relatively low WIS loads. In this study, we obtained ethanol concentrations above 40 g L , which is generally regarded as the lower limit for costeffective recovery of ethanol [45,46], with a WIS load of 10 wt%. The improved xylose utilization and overall ethanol yield are also expected to benefit the overall process economics [3,4].…”

Section: Process Considerationsmentioning

confidence: 99%

Sequential Targeting of Xylose and Glucose Conversion in Fed-Batch Simultaneous Saccharification and Co-fermentation of Steam-Pretreated Wheat Straw for Improved Xylose Conversion to Ethanol

et al. 2017

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Efficient conversion of both glucose and xylose in lignocellulosic biomass is necessary to make secondgeneration bioethanol from agricultural residues competitive with first-generation bioethanol and gasoline. Simultaneous saccharification and co-fermentation (SSCF) is a promising strategy for obtaining high ethanol yields. However, with this method, the xylose-fermenting capacity and viability of yeast tend to decline over time and restrict the xylose utilization. In this study, we examined the ethanol production from steampretreated wheat straw using an established SSCF strategy with substrate and enzyme feeding that was previously applied to steam-pretreated corn cobs. Based on our findings, we propose an alternative SSCF strategy to sustain the xylose-fermenting capacity and improve the ethanol yield. The xylose-rich hydrolyzate liquor was separated from the glucose-rich solids, and phases were co-fermented sequentially. By prefermentation of the hydrolyzate liquor followed fedbatch SSCF, xylose, and glucose conversion could be targeted in succession. Because the xylose-fermenting capacity declines over time, while glucose is still converted, it was advantageous to target xylose conversion upfront. With our strategy, an overall ethanol yield of 84% of the theoretical maximum based on both xylose and glucose was reached for a slurry with higher inhibitor concentrations, versus 92% for a slurry with lower inhibitor concentrations. Xylose utilization exceeded 90% after SSCF for both slurries. Sequential targeting of xylose and glucose conversion sustained xylose fermentation and improved xylose utilization and ethanol yield compared with fed-batch SSCF of whole slurry.

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Section: Process Considerationsmentioning

confidence: 99%

Sequential Targeting of Xylose and Glucose Conversion in Fed-Batch Simultaneous Saccharification and Co-fermentation of Steam-Pretreated Wheat Straw for Improved Xylose Conversion to Ethanol

et al. 2017

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“…Portanto, em analogia aos ensaios que não sofreram deslignificação, não houve divergência significativa entre os seus resultados e os resultados obtidos após etapa de deslignificação, visto que nos ensaios em que a biomassa não sofreu tratamento alcalino foram obtidos rendimentos similares. Viikari et al, (2012) [19] afirmaram que a hidrólise mostra-se significativamente melhorada após PTH, a despeito da presença da lignina, efeito que esteve em acordo com os resultados obtidos nesse trabalho.…”

Section: Experimentos De Hidrólise Realizados Com Carga De Sólidos Deunclassified

“…Porém, perspectivas positivas são apresentadas por Viikari et al (2012) [19], no qual os autores relataram que os custos associados a etapa de hidrólise enzimática tendem a diminuir significativamente nos próximos anos. Oliveira et al (2014) [7] avaliaram um processo combinado (pré-tratamento hidrotérmico seguido de deslignificação alcalina e posterior hidrólise enzimática) para a produção de bioetanol a partir da palha de cana-de-açúcar.…”

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Otimização de parâmetros operacionais do pré-tratamento da palha de cana-de-açúcar

et al. 2017

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O compromisso de atender as necessidades do presente sem comprometer a possibilidade de suprir as necessidades das gerações futuras, torna a diversificação da matriz energética brasileira e mundial fator cada vez mais compulsório. Diante disso, o uso de biomassas lignocelulósicas para obtenção de combustíveis mais limpos do ponto de vista ambiental é amplamente discutido na atualidade. O etanol combustível pode ser obtido a partir de fontes alternativas de energia, como as biomassas lignocelulósicas. Esse tipo de matéria-prima possui elevado teor de açúcares fermentescíveis em sua composição. Porém, esses não se encontram diretamente disponíveis, sendo necessárias etapas adicionais para sua obtenção. Este trabalho teve como objetivo a otimização da etapa de pré-tratamento da palha de cana-de-açúcar, por meio de um delineamento experimental 2 2 com três repetições no ponto central. As variáveis de estudo foram: a razão palha/água (m/v) na etapa de pré-tratamento hidrotérmico e a temperatura reacional do pré-tratamento alcalino sequencial ao hidrotérmico. O estudo mostrou que a deslignificação não promoveu melhora significativa na conversão da celulose em glicose na hidrólise enzimática, o que não justifica a realização dessa etapa adicional, nas condições avaliadas. Já o pré-tratamento hidrotérmico apresentou bons resultados, alcançando na etapa de hidrólise conversões superiores a 85%, em especial para as razões palha/água 1:6,7 e 1:20 (m/v).Palavras-chave: palha de cana-de-açúcar, otimização, pré-tratamento sequencial, pré-tratamento hidrotérmico, bioetanolThe commitment to meeting the needs of the present without compromising the ability to meet the needs of future generations makes the diversification of the Brazilian and the global energy matrix a compulsory factor. Thus, the use of lignocellulosic biomass to obtain cleaner fuels from an environmental point of view is widely discussed today. Fuel ethanol has been obtained from alternative energy sources, as lignocellulosic biomass. This type of biomass has high content of fermentable sugars. However, these sugars were not directly available, which need to include additional steps in the process to achieve this goal. This study aims to carry out an operational parameters optimization in the sugarcane straw pretreatment through a 2 2 experimental design with three replications at the central point. The study variables were: straw-water ratio (m/v) in the hydrothermal pretreatment and the temperature reaction in the alkaline pretreatment, sequential to hydrothermal. The study reveals that the delignification did not promote significant improvements in glucose conversion during the enzymatic hydrolysis. Thus, this addition step was not justified, under the evaluated conditions. Furthermore, the hydrothermal pretreatment showed good results reaching conversions higher than 85% in the hydrolysis step, in particular for the straw-water ratios 1:6.7 and 1:20 (m/v).

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“…Cellulolytic fungi (T. reesei, Aspergillus spp., Fusarium spp., Rhizopus spp.) including thermophilic fungi, such as T. emersonii and T. aurantiacus, produce a high concentration of cellulase enzymes to digest lignocellulose efficiently, assimilate all ligno-cellulosic sugars and convert these sugars to ethanol, showing that they naturally possess all pathways for the conversion of lignocellulose to bioethanol [39]. The efficiencies of the degradation of cellulose were dependent on the nature and concentration of the compounds added in the SSF system.…”

Section: Multi-enzymes Production Studies In Single Tray Solid State mentioning

confidence: 99%

Multi-enzymes Production Studies in Single Tray Solid State Fermentation with Opened and Closed System

Manan¹,

Webb²

2016

JLS

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Abstract:The robustness of A. awamori and A. oryzae as enzyme producers is exploited in fungal fermentation on agricultural solid waste. High-level production of extracellular glucoamylase, protease, cellulase and xylanase has been achieved. Three different types of 'waste' solids (wheat bran, soybean hulls and rapeseed meal) have been used in studies of solid state fermentation (SSF). The enzymes could be produced in significant levels by continuously supplying oxygen (O 2 ) through the tray system known as "closed" and "opened" tray systems. A perforated tray system was developed in this study that permits direct access to O 2 . Testing the tray system with different perforated mesh aperture sizes in this study did not yield different results in growth performance of A. awamori and A. oryzae. A. awamori and A. oryzae can be very versatile in producing various enzymes with different substrates with different starch, protein, hemicellulose and cellulose contents. These studies indicate that A. awamori is more suitable for the efficient production of multiple enzymes in the closed system including xylanase and cellulase, while the production of glucoamylase and protease is superior in the opened system. A. oryzae is more suitable for the efficient production of protease and cellulase in the closed system, while the production of protease is more favourable the opened system. A. awamori efficiently consumed starch in wheat bran medium and produced very high glucoamylase activity, and after that, the fungus efficiently produced other enzymes to degrade other complex nutrients such as protein, hemicellulose and cellulose. Meanwhile, A. oryzae efficiently consumed protein in rapeseed meal and produced very high protease activity. The ability of both filamentous fungi, to convert biomass through SSF bioconversion will have a great impact on food and agro-industry in every aspect of life from food and medicine to fuel.

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Lignocellulosic ethanol: From science to industry

Cited by 234 publications

References 67 publications

Sequential Targeting of Xylose and Glucose Conversion in Fed-Batch Simultaneous Saccharification and Co-fermentation of Steam-Pretreated Wheat Straw for Improved Xylose Conversion to Ethanol

Sequential Targeting of Xylose and Glucose Conversion in Fed-Batch Simultaneous Saccharification and Co-fermentation of Steam-Pretreated Wheat Straw for Improved Xylose Conversion to Ethanol

Otimização de parâmetros operacionais do pré-tratamento da palha de cana-de-açúcar

Multi-enzymes Production Studies in Single Tray Solid State Fermentation with Opened and Closed System

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