Bioethanol production from a sub-product of pulping industry

A vida da sociedade atual é dependente dos recursos fósseis, tanto a nível de energia como de materiais. No entanto, tem-se verificado uma redução das reservas destes recursos, ao mesmo tempo que as necessidades da sociedade continuam a aumentar, tornando cada vez mais necessárias, a produção de biocombustíveis e produtos químicos. Atualmente o etanol é produzido industrialmente a partir da cana-de-açúcar e milho, matérias-primas usadas na alimentação humana e animal. Este fato desencadeou o aumento de preços dos alimentos em todo o mundo e, como consequência, provocou uma série de distúrbios sociais. Os subprodutos industriais, recursos independentes das cadeias alimentares, têm-se posicionado como fonte de matérias-primas potenciais para bioprocessamento. Neste sentido, surgem os subprodutos gerados em grande quantidade pela indústria papeleira. Os licores de cozimento da madeira ao sulfito ácido (SSLs) são uma matériaprima promissora, uma vez que durante este processo os polissacarídeos da madeira são hidrolisados originando açúcares fermentáveis. A composição dos SSLs varia consoante o tipo de madeira usada no processo de cozimento (de árvores resinosas, folhosas ou a mistura de ambas). O bioprocessamento do SSL proveniente de folhosas (HSSL) é uma metodologia ainda pouco explorada. O HSSL contém elevadas concentrações de açúcares (35-45 g.L-1), na sua maioria pentoses. A fermentação destes açúcares a bioetanol é ainda um desafio, uma vez que nem todos os microrganismos são capazes de fermentar as pentoses a etanol. De entre as leveduras capazes de fermentar naturalmente as pentoses, destaca-se a Scheffersomyces stipitis, que apresenta uma elevada eficiência de fermentação. No entanto, o HSSL contém também compostos conhecidos por inibirem o crescimento de microrganismos, dificultando assim o seu bioprocessamento. Neste sentido, o principal objetivo deste trabalho foi a produção de bioetanol pela levedura S. stipitis a partir de HSSL, resultante do cozimento ao sulfito ácido da madeira de Eucalyptus globulus. Para alcançar este objetivo, estudaram-se duas estratégias de operação diferentes. Em primeiro lugar estudou-se a bio-desintoxicação do HSSL com o fungo filamentoso Paecilomyces variotii, conhecido por crescer em resíduos industriais. Estudaram-se duas tecnologias fermentativas diferentes para a biodesintoxicação do HSSL: um reator descontínuo e um reator descontínuo sequencial (SBR). A remoção biológica de inibidores do HSSL foi mais eficaz quando se usou o SBR. P. variotii assimilou alguns inibidores microbianos como o ácido acético, o ácido gálico e o pirogalol, entre outros. Após esta desintoxicação, o HSSL foi submetido à fermentação com S. stipitis, na qual foi atingida a concentração máxima de etanol de 2.36 g.L-1 com um rendimento de 0.17 g.g-1. P. variotti, além de desintoxicar o HSSL, também é útil na produção de proteína microbiana (SCP) para a alimentação animal pois, a sua biomassa é rica em proteína. O estudo da produção de SCP por P. variotii foi efetuado num SBR com HSSL sem suplementos e suplementado com sais. A melhor produção de biomassa foi obtida no HSSL sem adição de sais, tendo-se obtido um teor de proteína elevado (82,8%), com uma baixa concentração de DNA (1,1%). A proteína continha 6 aminoácidos essenciais, mostrando potencial para o uso desta SCP na alimentação animal e, eventualmente, em nutrição humana. Assim, a indústria papeleira poderá integrar a produção de bioetanol após a produção SCP e melhorar a sustentabilidade da indústria de pastas. A segunda estratégia consistiu em adaptar a levedura S. stipitis ao HSSL de modo a que esta levedura conseguisse crescer e fermentar o HSSL sem remoção de inibidores. Operou-se um reator contínuo (CSTR) com concentrações crescentes de HSSL, entre 20 % e 60 % (v/v) durante 382 gerações em HSSL, com uma taxa de diluição de 0.20 h-1. A população adaptada, recolhida no final do CSTR (POP), apresentou uma melhoria na fermentação do HSSL (60 %), quando comparada com a estirpe original (PAR). Após esta adaptação, a concentração máxima de etanol obtida foi de 6.93 g.L-1, com um rendimento de 0.26 g.g-1. POP possuía também a capacidade de metabolizar, possivelmente por ativação de vias oxidativas, compostos derivados da lenhina e taninos dissolvidos no HSSL, conhecidos inibidores microbianos. Por fim, verificou-se também que a pré-cultura da levedura em 60 % de HSSL fez com que a estirpe PAR melhorasse o processo fermentativo em HSSL, em comparação com o ensaio sem pré-cultura em HSSL. No entanto, no caso da estirpe POP, o seu metabolismo foi redirecionado para a metabolização dos inibidores sendo que a produção de etanol decresceu.

Biochemical effects of ethanol on oreochromis mossambicus (Peters)

The present study dealt with the haematological, biochemical and istopathological impacts of different sub lethal concentrations of ethanol on a euryhaline teleost Oreochromis In05.s‘ambicu.5' (Peters).Studies carried out using GC indicated an increase in blood ethanol oncentration of the fish which mainly arose due to fishes entering into a state of hypoxia which explains ethanol production as an ubiquitous “anaerobic” end product, which gets accumulated whenever metabolic demand exceeds the mitochondrial oxidative potential. The very low amount of ethanol detected in the control group ofO mossambicns was mainly due to the activity of microorganisms in the gut ofO. Nzossambicus.Oedcma observed in the present study, is a defense mechanism that reduces the branchial superficial area of the fish which comes in contact with the external milieu. These mechanisms also increase the diffusion barrier to the pollutant. Dilation of the blood vessels is due to increased permeability helping in the free passage of ethanol into the blood stream. Telangiectasis observed explains the state of asphyxia of the fish when subjected to ethanol toxicity indicating acute respiratory distress. Gill aneurysm observed indicates impaired respiratory function. This is related to the rupture of the pillar cells which results in an increased blood flow inside the lamellae, causing dilation of the blood vessel or even aneurysm of gill.The present findings warrant future studies to explore A'T'Pases as possible biomarkers of pollutant exposure in ecotoxicology. This study indicated that O. mossambicus when exposed for 7 and 21 days to ethanol was under tremendous stress and parameters employed in this study can be adapted for future investigations as biomarkers of damage caused by ethanol to aquatic organisms. The present study revealed that O. mossambicus is sensitive to sub lethal concentrations of ethanol.

Brazil and the USA: rethinking the future of ethanol for stronger mutual wns

A produção de etanol e a dominação da indústria, historicamente, tem sido uma fonte de discórdia para seus dois principais produtores. Os EUA com seu etanol de milho e o Brasil com sua etanol de cana, são os dois maiores produtores mundiais de etanol (1º EUA; 2º Brasil) e tem competido pela participação de mercado mundial há décadas. A partir de Dezembro de 2011, os EUA levantaram as tarifas e os subsídios que foram instalados para proteger sua indústria de etanol, o que muda o campo de jogo da produção mundial de etanol para o futuro. Atualmente em todo o mundo, o etanol é usado em uma proporção muito menor comparativamente a outros combustíveis. Esta pesquisa analisa o nível potencial de colaboração entre os EUA e o Brasil, facilitando um diálogo entre os stakeholders em etanol. A pesquisa consiste principalmente de conversas e entrevistas, com base em um conjunto de perguntas destinadas a inspirar conversas detalhadas e expansivas sobre os temas de relações Brasil-EUA e etanol. Esta pesquisa mostra que o etanol celulósico, que é também conhecido como etanol de segunda geração, oferece mais oportunidades de parceria entre os EUA e o Brasil, como há mais oportunidades para pesquisa e desenvolvimento em conjunto e transferência de tecnologia nesta área. Enquanto o etanol de cana no Brasil ainda é uma indústria próspera e crescente, o milho e a cana são muito diferentes geneticamente para aplicar as mesmas inovações exatas de um etanol de primeira geração, por outro. As semelhanças entre os processos de fermentação e destilação entre as matérias-primas utilizadas nos EUA e no Brasil para o etanol de segunda geração torna o investimento conjunto nesta área mais sensível. De segunda geração é uma resposta para a questão "alimentos versus combustíveis". Esta pesquisa aplica o modelo de co-opetição como um quadro de parceria entre os EUA e o Brasil em etanol celulósico. A pesquisa mostra que enquanto o etanol pode não ser um forte concorrente com o petróleo no futuro imediato, ele tem melhores perspectivas de ser desenvolvido como um complemento ao petróleo, em vez de um substituto. Como os EUA e o Brasil tem culturas de misturar etanol com petróleo, algo da estrutura para isso já está em vigor, a relação de complementaridade seria fortalecido através de uma política de governo clara e de longo prazo. A pesquisa sugere que apenas através desta colaboração, com toda a partilha de conhecimentos técnicos e estratégias econômicas e de desenvolvimento, o etanol celulósico será um commodity negociado mundialmente e uma alternativa viável a outros combustíveis. As entrevistas com os interessados em que esta pesquisa se baseia foram feitas ao longo de 2012. Como a indústria de etanol é muito dinâmica, certos eventos podem ter ocorrido desde esse tempo para modificar ou melhorar alguns dos argumentos apresentados.

Advances and Developments in Strategies to Improve Strains of Saccharomyces cerevisiae and Processes to Obtain the Lignocellulosic Ethanol-A Review

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development of rapidly fermenting strains of saccharomyces-diastaticus for direct conversion of starch and dextrins to ethanol

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Anaerobic digestion of stillage to produce bioenergy in the sugarcane-to-ethanol industry

Stillage is the main wastewater from ethanol production, containing a high chemical oxygen demand in addition to acidic and corrosive characteristics. Though stillage may be used as a soil fertilizer, its land application may be considered problematic due its high polluting potential. Anaerobic digestion represents an effective alternative treatment to reduce the pollution load of stillage. In addition, the methane gas produced within the process may be converted to energy, which can be directly applied to the treatment plant. The objective of this paper was to investigate the energetic potential of anaerobic digestion applied to stillage in the sugarcane ethanol industry. An overall analysis of the results indicates energy recovery capacity (ERC) values for methane ranging from 3.5% to 10%, respectively, for sugarcane juice and molasses. The processes employed to obtain the fermentable broth, as well as the distillation step, represent the main limiting factors to the energetic potential feasibility. Considering financial aspects the annual savings could reach up to US$ 30 million due to anaerobic digestion of stillage in relatively large-scale distilleries (365,000 m3 of ethanol per year). The best scenarios were verified for the association between anaerobic digestion of stillage and combustion of bagasse. In this case, the fossil fuels consumption in distilleries could be fully ceased, such the ERC of methane could reach values ranging from 140% to 890%. © 2013 Taylor & Francis.

Thermodynamic and economic analysis of hydrogen production integration in the Brazilian sugar and alcohol industry

One of the biggest challenges today is to develop clean fuels, which do not emit pollutant and with viable implementation. One of the options currently under study is the hydrogen production process. In this context, this work aims to study the technical and economical aspects of the incorporation process of hydrogen producing by ethanol steam reforming in the sugar cane industry and MCFC (molten carbonate fuel cell) application on it to generate electric power. Therefore, it has been proposed a modification in the traditional process of sugar cane industry, in order to incorporate hydrogen production, besides the traditional products (sugar, ethylic, hydrated and anhydric alcohol). For this purpose, a detailed theoretical study of the ethanol production process, describing the considerations to incorporate the hydrogen production will be performed. After that, there will be a thermodynamic study for analysing the innovation of this production chain, as well as a study of economic engineering to allocate the costs of products of the new process, optimising it and considering the thermoeconomics as being as an analysis tool. This proposal aims to improve Brazil's position in the ranking of international biofuels, corroborating the nation to be a power in the hydrogen era. (C) 2013 Elsevier Ltd. All rights reserved.

Greenhouse gas balance associated with sugarcane production in South-Central Brazil, considering the management and expansion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Physical characterization of particleboard produced with waste from ethanol and sugar mill

The problem of proper disposal of solid waste generated in different industrial processes is one of worldwide environmental concerns nowadays. Thus, this study aimed to establish a new alternative for the disposal of two agro-industrial residues employing them to produce particleboard for different purposes in building construction. The focus was given to the reuse of the sugarcane bagasse (SB) originated during the processing of Saccharum officinarum for sugar and ethanol production, and bamboo stem leaves of Dendrocalamus giganteus(BB). For this, six particleboards were produced in the following compositions: with 100% SB, 75% SB + 25% BB, 50% SB+50% BB, 40% SB +60 BB, 25% SB+ 75% BB and 100% BB in the total mass of the composites. The particleboards physical characterization followed Brazilian Standard ABNT NBR 14810-3 to density, moisture content and water absorption. Results showed these raw materials are compatible to particleboard production.

Whole-genome sequencing of the efficient industrial fuel-ethanol fermentative Saccharomyces cerevisiae strain CAT-1

The Saccharomyces cerevisiae strains widely used for industrial fuel-ethanol production have been developed by selection, but their underlying beneficial genetic polymorphisms remain unknown. Here, we report the draft whole-genome sequence of the S. cerevisiae strain CAT-1, which is a dominant fuel-ethanol fermentative strain from the sugarcane industry in Brazil. Our results indicate that strain CAT-1 is a highly heterozygous diploid yeast strain, and the similar to 12-Mb genome of CAT-1, when compared with the reference S228c genome, contains similar to 36,000 homozygous and similar to 30,000 heterozygous single nucleotide polymorphisms, exhibiting an uneven distribution among chromosomes due to large genomic regions of loss of heterozygosity (LOH). In total, 58 % of the 6,652 predicted protein-coding genes of the CAT-1 genome constitute different alleles when compared with the genes present in the reference S288c genome. The CAT-1 genome contains a reduced number of transposable elements, as well as several gene deletions and duplications, especially at telomeric regions, some correlated with several of the physiological characteristics of this industrial fuel-ethanol strain. Phylogenetic analyses revealed that some genes were likely associated with traits important for bioethanol production. Identifying and characterizing the allelic variations controlling traits relevant to industrial fermentation should provide the basis for a forward genetics approach for developing better fermenting yeast strains.

Steam explosion pretreatment reproduction and alkaline delignification reactions performed on a pilot scale with sugarcane bagasse for bioethanol production

This work was focused on the steam explosion pretreatment reproduction and alkaline delignification reactions on a pilot scale for the ethanol production, through different varieties of natural sugarcane bagasse, pretreated bagasse and delignified pretreated bagasse (cellulosic pulp). The possible chemical composition differences of the various types of bagasse, as well as the chemical composition variations of the materials in the 20 processes of pretreatment and delignification on the pilot scale were verified. The analytical results of the 20 samples of most diverse varieties and origins of natural sugarcane bagasse considering planting soils, planting periods and weather; show no significant chemical differences. It is evident that only with the chemical composition it is not possible to verify the differences between the varieties of sugarcane bagasses. The research results may offer some evidences of these varieties, but it is not a reliable parameter. The pilot process of steam explosion pretreatment and the alkaline delignification process of pretreated material showed through analytical results a good capacity of reproduction, as the standard differences were below 2.7. The average allowed in the pretreatment and alkaline delignification processes were 66.1 +/- 0.8 and 51.5 +/- 2.6 respectively, ensuring an excellent reproduction capacity of the processes obtained through chemical characterizations. (C) 2011 Elsevier B.V. All rights reserved.

Exergy efficiency analysis of chemical and biochemical stages involved in liquid biofuels production processes

Liquid biofuels can be produced from a variety of feedstocks and processes. Ethanol and biodiesel production processes based on conventional raw materials are already commercial, but subject to further improvement and optimization. Biofuels production processes using lignocellulosic feedstocks are still in the demonstration phase and require further R&D to increase efficiency. A primary tool to analyze the efficiency of biofuels production processes from an integrated point of view is offered by exergy analysis. To gain further insight into the performance of biofuels production processes, a simulation tool, which allows analyzing the effect of process variables on the exergy efficiency of stages in which chemical or biochemical reactions take place, were implemented. Feedstocks selected for analysis were parts or products of tropical plants such as the fruit and flower stalk of banana tree, palm oil, and glucose syrups. Results of process simulation, taking into account actual process conditions, showed that the exergy efficiencies of the acid hydrolysis of banana fruit and banana pulp were in the same order (between 50% and 60%), lower than the figure for palm oil transesterification (90%), and higher that the exergy efficiency of the enzymatic hydrolysis of flower stalk (20.3%). (C) 2011 Elsevier Ltd. All rights reserved.

Adding value to the Brazilian sisal: acid hydrolysis of its pulp seeking production of sugars and materials

The present work is inserted into the broad context of the upgrading of lignocellulosic fibers. Sisal was chosen in the present study because more than 50% of the world's sisal is cultivated in Brazil, it has a short life cycle and its fiber has a high cellulose content. Specifically, in the present study, the subject addressed was the hydrolysis of the sisal pulp, using sulfuric acid as the catalyst. To assess the influence of parameters such as the concentration of the sulfuric acid and the temperature during this process, the pulp was hydrolyzed with various concentrations of sulfuric acid (30-50%) at 70 A degrees C and with 30% acid (v/v) at various temperatures (60-100 A degrees C). During hydrolysis, aliquots were withdrawn from the reaction media, and the solid (non-hydrolyzed pulp) was separated from the liquid (liquor) by filtering each aliquot. The sugar composition of the liquor was analyzed by HPLC, and the non-hydrolyzed pulps were characterized by viscometry (average molar mass), and X-ray diffraction (crystallinity). The results support the following conclusions: acid hydrolysis using 30% H2SO4 at 100 A degrees C can produce sisal microcrystalline cellulose and the conditions that led to the largest glucose yield and lowest decomposition rate were 50% H2SO4 at 70 A degrees C. In summary, the study of sisal pulp hydrolysis using concentrated acid showed that certain conditions are suitable for high recovery of xylose and good yield of glucose. Moreover, the unreacted cellulose can be targeted for different applications in bio-based materials. A kinetic study based on the glucose yield was performed for all reaction conditions using the kinetic model proposed by Saeman. The results showed that the model adjusted to all 30-35% H2SO4 reactions but not to greater concentrations of sulfuric acid. The present study is part of an ongoing research program, and the results reported here will be used as a comparison against the results obtained when using treated sisal pulp as the starting material.

Fermentation medium and oxygen transfer conditions that maximize the xylose conversion to ethanol by Pichia stipitis

The xylose conversion to ethanol by Pichia stipitis was studied. In a first step, the necessity of supplementing the fermentation medium with urea. MgSO(4) x 7H(2)O, and/or yeast extract was evaluated through a 2(3) full factorial design. The simultaneous addition of these three nutritional sources to the fermentation medium, in concentrations of 2.3, 1.0, and 3.0 g/l, respectively, showed to be important to improve the ethanol production in detriment of the substrate conversion to cell. In a second stage, fermentation assays performed in a bioreactor under different K(L)a (volumetric oxygen transfer coefficient) conditions made possible understanding the influence of the oxygen transfer on yeast performance, as well as to define the most suitable range of values for an efficient ethanol production. The most promising region to perform this bioconversion process was found to be between 2.3 and 4.9 h(-1), since it promoted the highest ethanol production results with practically exhaustion of the xylose from the medium. These findings contribute for the development of an economical and efficient technology for large scale production of second generation ethanol. (C) 2011 Elsevier Ltd. All rights reserved.

Biotechnological Utilization of Biodiesel-Derived Glycerol for the Production of Ribonucleotides and Microbial Biomass

Ten yeast strains were evaluated concerning their capabilities to assimilate biodiesel-derived glycerol in batch cultivation. The influence of glycerol concentration, temperature, pH and yeast extract concentration on biomass production was studied for the yeast selected. Further, the effect of agitation on glycerol utilization by the yeast Hansenula anomala was also studied. The yeast H. anomala CCT 2648 showed the highest biomass yield (0.30 g g(-1)) and productivity (0.19 g L-1 h(-1)). Citric acid, succinic acid, acetic acid and ethanol were found as the main metabolites produced. The increase of yeast extract concentration from 1 to 3 g L-1 resulted in high biomass production. The highest biomass concentration (21 g L-1), yield (0.45 g g(-1)) and productivity (0.31 g L-1 h(-1)), as well as ribonucleotide production (13.13 mg g(-1)), were observed at 700 rpm and 0.5 vvm. These results demonstrated that glycerol from biodiesel production process showed to be a feasible substrate for producing biomass and ribonucleotides by yeast species.