Second-generation bioethanol from industrial wood waste of South American species

There is a global interest in replacing fossil fuels with renewable sources of energy. The present review evaluates the significance of South-American wood industrial wastes for bioethanol production. Four countries have been chosen for this review, i.e., Argentina, Brazil, Chile, and Uruguay, based on their current or potential forestry industry. It should be noted that although Brazil has a global bioethanol market share of 25%, its production is mainly first-generation bioethanol from sugarcane. The situation in the other countries is even worse, in spite of the fact that they have regulatory frameworks in place already allowing the substitution of a percentage of gasoline by ethanol. Pines and eucalyptus are the usually forested plants in these countries, and their industrial wastes, as chips and sawdust, could serve as promising raw materials to produce second-generation bioethanol in the context of a forest biorefinery. The process to convert woody biomass involves three stages: pretreatment, enzymatic saccharification, and fermentation. The operational conditions of the pretreatment method used are generally defined according to the physical and chemical characteristics of the raw materials and subsequently determine the characteristics of the treated substrates. This article also reviews and discusses the available pretreatment technologies for eucalyptus and pines applicable to South-American industrial wood wastes, their enzymatic hydrolysis yields, and the feasibility of implementing such processes in the mentioned countries in the frame of a biorefinery.Fil: Vallejos, María Evangelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Kruyeniski, Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Area, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentin

Influencia del pretratamiento de residuos forestoindustriales sobre la producción de bioetanol

El interés global por el uso y la producción de biocombustibles ha crecido significativamente en la última década enfocado en la reducción de gases de efecto invernadero. Existen políticas nacionales e internacionales que contemplan subsidios y exención de impuestos, así como directivas respecto a las mezclas que influyen en la producción de biocombustibles. Una biorrefinería forestal puede procesar residuos lignocelulósicos (aserrín, corteza, trozos de madera) para producir energía, productos químicos y biomateriales, análogamente a las refinerías de petróleo. En la región Noreste de Argentina (NEA) la industria de la madera es muy importante y el aserrín (de pino y eucaliptus) es uno de los principales desechos de su industrialización primaria. Se estima que hay 1,5 millones de toneladas secas al año de residuos que no son debidamente aprovechados. La producción de bioetanol de segunda generación a partir de la celulosa (presente en el residuo lignocelulósico) involucra tres etapas básicas: fraccionamiento o pretratamiento, hidrólisis enzimática y fermentación. La primera etapa tiene como objetivo extraer hemicelulosas y lignina, evitando la formación de subproductos inhibidores para la hidrólisis y/o fermentación y abrir la estructura del material para mejorar la accesibilidad a los componentes restantes (principalmente celulosa) en las posteriores etapas de procesamiento. Las enzimas (empleadas en la hidrólisis) y el substrato (material pretratado) son los principales factores que influyen en la hidrólisis enzimática, directamente relacionada con el pretratamiento al cual es sometido el material.La hipótesis de este trabajo es que la calidad del material fibroso (específicamente, celulosa de diferente calidad y pureza proveniente de aserrines pretratados) tiene influencia sobre su conversión a bioetanol.El objetivo general de este trabajo es encontrar los requisitos de calidad que debe poseer el material lignocelulósico pretratado para maximizar la conversión a bioetanol mediante procesos técnicamente viables y económicamente y ambientalmente sostenibles.Para esto se empleó aserrín de pino sometido a diferentes pretratamientos, como ser: desresinación alcalina, hidrólisis ácida diluida, soda-AQ (antraquinona), soda-AQ-oxígeno, Kraft-AQ, explosión de vapor (EV, con o sin lavado alcalino posterior), soda-etanol, soda, etanol y combinaciones de algunos de los tratamientos mencionados. El aserrín sin pretratar también fue sometido a hidrólisis enzimática. Luego de determinar la digestibilidad de los materiales, se seleccionaron ocho muestras (en base a su composición química y rendimiento de la hidrólisis enzimática) y se evaluó su cristalinidad y porosidad, por medio de rayos X y termoporosimetría, respectivamente.Todos los pretratamientos aplicados aumentaron el rendimiento de la hidrólisis enzimática (digestibilidad) frente a la hidrólisis del aserrín sin pretratamiento. Los pretratamientos realizados para extraer hemicelulosas o extractivos, como hidrólisis ácida diluida, explosión de vapor y desresinación alcalina, no mejoraron significativamente la digestibilidad. El máximo rendimiento alcanzado fue del 25% a las 72 h con EV, demostrando que la extracción de hemicelulosas participa con un rol menor en la digestibilidad.Por el contrario, los tratamientos fuertemente alcalinos que promovieron mayor remoción de lignina, mejoraron la accesibilidad del material a la acción enzimática. En concordancia, se obtuvieron altos valores de cristalinidad de la celulosa (IC alrededor de 75-76%). Los ensayos de termoporosimetría mostraron que los pretratamientos aumentaron el número de poros pero no su diámetro. El orden de porosidades fue: aserrín sin pretratamientoThe global interest for the use and production of biofuels has significantly increased in the last decade, with special focus on the reduction of greenhouse gases emission. There are national and international policies which include subsidies and taxes exemption as well as directives regarding the mixtures that influence the production of biofuels. A forest biorefinery can process lignocellulosic waste (sawdust, bark, wood chip) to produce energy, chemical products and biomaterials, similar to petroleum refineries. In the Northeast region of Argentina (NEA), the wood industry is very important and sawdust (mainly from pine and eucalyptus) is one of the main wastes of its primary industrialization. It is estimated that there are 1.5 million dry tons per year of waste that are not properly used. The production of second generation bioethanol from cellulose (present in the lignocellulosic waste) involves three basic stages: fractionation or pretreatment, enzymatic hydrolysis and fermentation. The aim of the first stage is to extract hemicelluloses and lignin, avoiding the formation of inhibitory by-products for hydrolysis and / or fermentation and to open the structure of the material to improve the accessibility to the remaining components (mainly cellulose) during the downstream processes.The enzymes (used in hydrolysis) and the substrate (pretreated material) are the main factors that influence the enzymatic hydrolysis, being the last one closely relatedto the pretreatment to which the material is subjected. The hypothesis of this work is that the quality of the fibrous material (specifically, cellulose of different quality and purity from pre-treated sawdust) has an influence on its conversion to bioethanol. The general objective of this work is to find the quality requirements that the lignocellulosic pretreated material must have to maximize their conversion to bioethanol, using processes technically viable and economically and environmentally sustainable. For this purpose pine sawdust was used and subjected to different pretreatments, such as alkaline deresination, diluted acid hydrolysis, soda-AQ (anthraquinone), soda-AQ-oxygen, Kraft-AQ, steam explosion (SE, with and without a posterior alkaline wash), soda-ethanol, soda, ethanol and a combination of some treatments. The untreated sawdust was also subjected to enzymatic hydrolysis. After determining the digestibility of the materials, eight samples were selected (based on their chemical composition and enzymatic hydrolysis yield) and their crystallinity and porosity were evaluated by means of X-rays and thermoporosimetry respectively. All studied pretreatments increased the enzymatic hydrolysisyield (digestibility) when compared to the hydrolysis of sawdust without pretreatment. The pretreatments accomplished to extract hemicelluloses or extractives as diluted acid hydrolysis, steam explosion, and alkaline deresination did not significantly improve the digestibility. The maximum yield reached was 25% at 72 h with EV, demonstrating that the extraction of hemicelluloses plays a minor role in digestibility. On the contrary, strongly alkaline treatments, which promoted greater lignin removal, improved the accessibility of the material to the enzymatic action. In agreement, high values of crystallinity index (CrI of around 75-76%) were obtained. The thermoporosity studies showed that all pretreatments increased the number of pores but not their diameter. The order found was: sawdust without pretreatmentFil: Kruyeniski, Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentin

Biomass Waste as Sustainable Raw Material for Energy and Fuels

Sustainable development is the common goal of the current concepts of bioeconomy and circular economy. In this sense, the biorefineries platforms are a strategic factor to increase the bioeconomy in the economic balance. The incorporation of renewable sources to produce fuels, chemicals, and energy, includes sustainability, reduction of greenhouse gases (GHG), and creating more manufacturing jobs fostering the advancement of regional and social systems by implementing the comprehensive use of available biomass, due to its low costs and high availability. This paper describes the emerging biorefinery strategies to produce fuels (bio-ethanol and γ-valerolactone) and energy (pellets and steam), compared with the currently established biorefineries designed for fuels, pellets, and steam. The focus is on the state of the art of biofuels and energy production and environmental factors, as well as a discussion about the main conversion technologies, production strategies, and barriers. Through the implementation of biorefineries platforms and the evaluation of low environmental impact technologies and processes, new sustainable production strategies for biofuels and energy can be established, making these biobased industries into more competitive alternatives, and improving the economy of the current value chains.Fil: Clauser, Nicolás Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: González, Roxana Giselle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Mendieta, Carolina Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Kruyeniski, Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Area, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Vallejos, María Evangelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Materiales de Misiones; Argentin

Enzymatic hydrolysis and fermentation strategies for the biorefining of pine sawdust

This work aims to evaluate second-generation bioethanol production from the soda-ethanol pulp of pine sawdust via two strategies: separate hydrolysis and fermentation and simultaneous saccharification and fermentation. A kinetics study of the enzymatic hydrolysis of separate hydrolysis and fermentation was included as a design tool. Three soda-ethanol pulps (with different chemical compositions), Cellic® Ctec2 cellulolytic enzymes, and Saccharomyces cerevisiae IMR 1181 (SC 1181) yeast were employed. The obtained kinetic parameters were as follows: an apparent constant (k) of 11.4 h-1, which represents the link frequency between cellulose and cellulase; a Michaelis-Menten apparent constant (KM) of 23.5 gL-1, that indicates the cellulose/cellulase affinity; and the apparent constant of inhibition between cellulose-glucose and cellulase (KI), which was 2.9 gL-1, 3.1 gL-1, and 6.6 gL-1 for pulps 1, 2, and 3, respectively. The kinetic model was applicable, since the calculated glucose values fit the experimental values. High bioethanol yields were obtained for pulp 3 in the separate hydrolysis and fermentation and simultaneous saccharification and fermentation processes (89.3% and 100% after 13 h and 72 h, respectively).Fil: Mendieta, Carolina Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Felissia, Fernando Esteban. Universidad Nacional de Misiones; ArgentinaFil: Arismendy Pabón, Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Kruyeniski, Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Area, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentin

Pretreatment soda-ethanol of pine and its influence on enzymatic hydrolysis

The production of second-generation bioethanol using pine sawdust involves pretreatment, enzymatic hydrolysis (EH) and fermentation. One of the most influencing factor in the cellulose hydrolysis is the chemical composition of the substrate, which is directly linked with the kind and conditions of the applied pretreatment to biomass. The aim of this work was to study the enzymatic digestibility of pine sawdust submitted to alkaline - ethanol pretreatments. In the experiments, we varied alkaline charges and time at maximum temperature. Laboratory Analytical Procedures (LAPs,NREL) were used for the chemical characterization of the material, the enzymatic activity and the hydrolysis. The pretreated materials presented different chemical compositions. Only the effect of alkaline charge on yield was significant. Ethanol and soda exhibited a positive synergy effect on yield. Results suggest the existence of a negative correlation between EH yield and lignin content.La obtención de bioetanol de segunda generación a partir de aserrín de pino incluye: pretratamiento, hidrólisis enzimática (HE) y fermentación. Uno de los factores más influyentes en la hidrólisis es la composición química del sustrato, directamente relacionada con las condiciones y tipo de pretratamiento al cual es sometido el material. El objetivo fue estudiar la digestibilidad enzimática del aserrín de pino sometido a un pretratamiento etanol-soda. En el experimento se varió la carga alcalina y el tiempo a temperatura máxima. Para la caracterización del material, la actividad enzimática y la hidrólisis se usaron los Procedimientos Analíticos de Laboratorio (LAPs, NREL). Los materiales pretratados presentaron diferente composición química. Solo el efecto de la carga alcalina sobre el rendimiento de la HE fue significativo. Etanol y soda exhibieron una sinergia positiva con respecto al rendimiento. Los resultados sugieren una correlación negativa entre el rendimiento de la HE y el contenido de lignina.Fil: Kruyeniski, Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Felissia, Fernando Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Area, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentin

Modelling of the Simultaneous Saccharification and Fermentation for a Pine Sawdust Biorefinery

The decline in world oil reserves evidences the need to diversify the sources of equivalent raw materials. The use of biomass is one of the most explored alternatives. This work evaluates the second-generation bioethanol (2G) production from a pine sawdust soda-ethanol pulp by simultaneous hydrolysis and fermentation (SSF) to obtain the best conditions for scaling up the process. Experimental designs have been used to find mathematical models that define the complex situation jointly varying time with other variables (enzyme load and temperature). Time periods in the full model varied from 0 h to 72 h. Given the results (curve shape differences), it was decided to split the design in two, covering periods from 0 h to 24 h (Model I) and from 24 to 72 h (Model II). The pulp chemical composition was 80.2% glucans, 7.2% xylans, 0.3% galactans, 8.4% mannans, 3.7% lignin. Cellic® Ctec2 cellulolytic enzymes were used for saccharification and Saccharomyces cerevisiae IMR 1181 (SC 1181) yeast for fermentation. The best conditions found in the two designs were 30 FPU g−1 glucans, 39°C, 24 h for Model I, and 30 FPU g−1 glucans, 35°C, 72 h for Model II. Fermentation optimal values were 63.23 and 81.93 for Models I and II, respectively.Fil: Mendieta, Carolina Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Kruyeniski, Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Felissia, Fernando Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Area, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentin

Physical and chemical characteristics of pretreated slash pine sawdust influence its enzymatic hydrolysis

The aim of this work was to evaluate the effect of different pretreatments applied to industrial slash pine sawdust (Pinus elliottii) on its enzymatic hydrolysis. NREL laboratory analytical procedures for standard biomass analysis were used to characterize the thirty one fibrous materials produced. Eight pretreated materials were selected considering both the chemical composition and the enzymatic hydrolysis yield to further evaluate crystallinity and porosity, determined by X-ray diffraction and thermoporosimetry, respectively. Diluted acid, steam explosion, and slight alkali treatments revealed to be not effective to enhance enzymatic hydrolysis of resinous pines since a maximum yield value of only 25% was achieved. On the contrary, strong alkali treatments promoted the lignin removal, thus increasing the accessibility of the material for enzymatic hydrolysis. In accordance, the highest values of the cellulose crystallinity (about 75–76%) were also obtained. No correlation was found between the porosity and the enzymatic hydrolysis yield. It was concluded that to enhance enzymatic hydrolysis the lignin content of the pretreated material should below. As for the hemicelluloses content, only its interaction with the lignin content is significant, as revealed by the regression model obtained

Kinetic study of the extraction of hemicellulosic carbohydrates from sugarcane bagasse by hot water treatment

Sugarcane bagasse is a lignocellulosic agro-industrial waste, which is usually burned in the sugar and bio-ethanol mills to produce heat and electricity. This work presents the kinetic study of the carbohydrates extracted from the mild hot water pretreatment of sugarcane bagasse, to explain the variation of hemicellulosic carbohydrates during the treatment. This could allow the selection of optimum conditions to obtain the desired products in spent liquors, as high concentration of xylans and low concentrations of fermentation inhibitors. Sugarcane bagasse was hydrothermally treated under isothermal conditions at 160, 170, and 180 ◦C, using a liquid to solid ratio of 14:1. Glucans, xylans, arabans, xylose, glucose, arabinose, acetic acid, formic acid, HMF and furfural were first identified in the spent liquor. A kinetic model was applied, considering the direct extraction of xylose and oligomers from the solid, xylose production from the oligomers, and furfural generation from xylose. It was supposed that the reaction rate constants have first-order kinetics. The fractionation by hydrothermal treatment has proven to be effective for hemicelluloses removal. Most glucans were retained in the solid, and a partial delignification (at 180 ◦C, 9.8% and 36.3% of the initial lignin at 20 and 240 min, respectively) was achieved. The maximum concentration of xylans in spent liquors with the low furfural content (0.5% on oven dry bagasse) was achieved at 180 ◦C and 20 min of treatment (17.6% on oven dry bagasse, about 74% of the initial amount). An activation energy of 128.8 kJ mol−1 has been obtained for the fast hydrolysis of xylans from sugar cane bagasse. The maximal concentration of xylans + xylose in liquors was obtained with a P-factor of 800.Fil: Vallejos, María Evangelina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; Argentina. Universidad Nacional de Misiones; ArgentinaFil: Felissia, Fernando Esteban. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; Argentina. Universidad Nacional de Misiones; ArgentinaFil: Kruyeniski, Julia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; Argentina. Universidad Nacional de Misiones; ArgentinaFil: Area, Maria Cristina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; Argentina. Universidad Nacional de Misiones; Argentin