Residues For Ethanol Production Research Articles

Simulation and economic evaluation of process alternatives for biogas production and purification from sugarcane vinasse

Vinasse, which is the main residue of ethanol production, is a promising alternative for the generation of biogas, due to its high generation rate and limited application. The objective of the present work is to simulate and economically compare alternative processes for the production and treatment of biogas from the anaerobic digestion of vinasse. Different water, H2S and CO2 removal technologies were evaluated: condensation, membrane separation, washing, Pressure Swing Adsorption (PSA), adsorptions with silica gel, activated carbon and metallic oxides, absorptions with triethylene glycol (TEG), ethylenediaminetetraacetic acid iron (III) (Fe/EDTA) and diethylamine (DEA). It was shown that an anaerobic lagoon is preferable over a set of Upflow Anaerobic Sludge Blanket (UASB) reactors due to the large processing scale, reducing the capital costs. Among the 12 evaluated routes, the best process alternative for biogas treatment was water removal through silica gel adsorption, followed by simultaneous H2S and CO2 absorption in a Fe/EDTA solution. In the best scenario, the entire biomethane production plant would require an investment of US$ 3.6 million, resulting in an annual net profit of US$ 1.99 million, with payback in the first year of operation.

Microbiota profile in mesophilic biodigestion of sugarcane vinasse in batch reactors.

The vinasse is a residue of ethanol production with the potential for methane production, requiring an allochthonous inoculum. Several microorganisms act in the different phases of anaerobic digestion, and the identification of these microbial communities is essential to optimize the process. The characterization of the microbiota involved in the biodigestion of vinasse was observed in the initial stage (IS), at the peak of methane production (MS) and the end of the process (FS) of the best performance assay by high-throughput sequencing. The highest methane production was 0.78 mmolCH4.gVS.h-1 at 243.7 h in the substrate/inoculum ratio of 1.7, with consumption partial of acetic, propionic and isobutyric acids and an 82% reduction of chemical oxygen demand. High microbial diversity was found. The genera Clostridium, Acinetobacter, Candidatus Cloacamonas, Bacteroides, Syntrophomonas, Kosmotoga, the family Porphyromonadaceae and the class Bacteroidia were the most abundant in the maximum methane production. Methane production was driven by Methanobacterium and Methanosaeta, suggesting the metabolic pathways used were hydrogenotrophic and acetoclastic.

Comparison of hydrogen and volatile fatty acid production by Bacillus cereus, Enterococcus faecalis and Enterobacter aerogenes singly, in co-cultures or in the bioaugmentation of microbial consortium from sugarcane vinasse

Abstract Vinasse is a main residue of ethanol production, generated daily in large scale in Brazil. The anaerobic processing of vinasse can be a sustainable alternative for generation of fuel and co-products. The production of hydrogen and VFAs from different concentrations of sugarcane vinasse were evaluated by Bacillus cereus, Enterobacter aerogenes and Enterococcus faecalis singly, as cocultures, in bioaugmentation and by microbial consortium. The increase of vinasse concentration positively affected the production of hydrogen. B. cereus alone showed the higher hydrogen production using undiluted vinasse (100%) (85.41 mmol H 2 L−1) and higher yield (5.40 mmolH2 g−1COD), for both vinasse concentration (50, 70 and 100%). The performance of co-culture (B. cereus + E. aerogenes + E. faecalis) was similar (2.45 mmol H 2 g−1 COD) to the microbial consortium (2.59 mmol H 2 g−1 COD). The bioaugmentation of microbial consortium with B. cereus, E. aerogenes and E. faecalis separately did not increase hydrogen production. Total VFAs yield increased in the 30% vinasse concentration. The main metabolite produced was butyric acid for singly microorganisms and microbial consortium. Whereas acetic acid was predominant in both co-culture and bioaugmentation assays. This study showed the potential of isolated strain B. cereus in the production of hydrogen and VFAs, using vinasse as a substrate, giving a sustainable destination for the residue of high polluting risk.

Dimethyl Ether Production from Sugarcane Vinasse: Modeling and Simulation for a Techno-economic Assessment

Industrialization and energy demand increase are highlighted as consequences of world population growth for decades. Thereby, aiming to contribute to sustainable processes capable of mitigating the effects resulting from this process, biofuels have been intensively researched, produced and used in recent years. Among the possibilities, dimethyl ether (DME) stands out with great prospects replacing liquefied petroleum gas and diesel due to its potential as clean fuel. This work aims to conjoin the production of DME, a biofuel with great prospects for technical performance, safety, and economy, with a favorable destination for vinasse, the most worrying residue of ethanol production, due to its high polluting potential and large production volume in several countries. A rigorous and robust simulation of direct synthesis of DME from vinasse-derived syngas is performed using Aspen Hysys and its supplements, evaluating the technical and economic aspects of its production in ethanol distilleries. Results of the proposed scenario point that the process is technically feasible, reaching a purity of 99.9%, respecting the minimum required by standard norms. In addition, the designed process achieved yields of 1 kg of DME for each 1.6 kg of syngas. The simulated process presented a total capital cost of 47.1 millions of dollars, operating costs of 14.1 millions of dollars per year, and utilities cost of 11.2 millions of dollars per year. Considering energy cogeneration, an economy of 9.2% was reached, resulting in a production cost of simulated stage of 98.36 US$/tonne of DME and, considering a complete scenario, an accumulated cost of 233.48 US$/tonne of DME. It demonstrates an economic competitiveness for the DME price and ensures a considerable profit margin for the process. Consequently, the investigated DME production scenario emerges as a promising diesel substitute in a realistic scenario.

New Proposal for Sugarcane Vinasse Treatment by Hydrothermal Carbonization: An Evaluation of Solid and Liquid Products

Vinasse is a residue of ethanol production from sugarcane. In view of the problems associated with its disposal, this study aimed to propose a treatment for vinasse by hydrothermal carbonization. The influence of temperature (100 to 200 oC), acidity (1.7 to 8.3%) and reaction time (12 to 48 h) on the hydrothermal treatment was evaluated, as well the characteristics of the solid (hydrochar) and liquid (process water) products. For the solid product, two hydrothermal carbonization conditions stood out as leading to higher carbonization and yields. These conditions were 200 oC, 8.3% acidity and times of 12 and 48 h. For the process water, the carbonization reaction at 200 oC, 8.3% acidity and 48 h produced the highest discoloration and 77% reduction of total organic carbon. Thus, hydrothermal carbonization proved to be an efficient method to treat vinasse, and the hydrochar presents potential for use as fertilizers / soil conditioners, and also the process water after pre-treatment.

Liquid-hot-water pretreatment of palm-oil residues for ethanol production: An economic approach to the selection of the processing conditions

Liquid Hot Water pretreatment (LHW) was evaluated on empty palm fruit bunch (EPFB) at 160–210 °C, residence time of 0–60 min and solid loadings of 5–25% wt. The effects of these conditions on ethanol yield and potential profit were determined. The “potential profit” was used as response variable to approach the economic feasibility because it helps to dismiss those experiments without economic sense, a task that the yield by itself is not capable. Ethanol yields between 109.6 and 172.1 L/ton dry fed biomass were obtained, the highest ethanol yield was obtained at conditions of 0 min, 5% of solids and 185 °C. Ethanol yield was favored at intermediate temperatures, low residence times and low solid loads. The potential profit was favored at intermediate temperature, lower residence times and high solid loads. The conditions for the optimal ethanol yield did not correspond to the conditions for the optimal potential profit. In fact, the experiment with the highest ethanol yield was not the one with the highest potential profit. Several other experimental conditions that led to moderate ethanol yields exhibited higher potential profits. These higher potential profits are mainly a consequence of higher ethanol concentrations obtained by working with high solid loading, which implies lower distillation costs. The best pretreatment conditions were 30 min, 15% solids and 185 °C because they led to the highest potential profit due to a synergetic effect of a high yield and a high concentration of ethanol.

Bioconversion of hemicellulosic materials into ethanol by yeast, Pichia kudriavzevii 2-KLP1, isolated from industrial waste

In the present work, a yeast strain Pichia kudriavzevii was identified on the basis of 18S rDNA, showing maximum growth at 30°C and pH 7.0. Among all the complex polysaccharides used, wheat bran proved to be the best substrate as indicated by the maximum growth of the yeast strain. The yeast isolate was capable of producing xylanase both intra- and extra-cellularly, the dominant form being extracellular. The maximum enzyme activity was determined at pH 5.0 and at 50°C. Na+, Mg2+ and Fe2+ presence caused a substantial increase in enzyme activity while a slight decrease (4.5%) was observed in the presence of Mn2+, Zn2+ and Cu2+. Pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activities were assayed to confirm the presence of the ethanol pathway and PDC activity was much more pronounced (73%) compared to ADH activity (51%). The yeast strain can be employed to utilize hemicellulose containing agroindustrial residues for ethanol production.

Evaluation of Lignin-Modifying Enzyme Activity of Trametes spp. (Agaricomycetes) Isolated from Georgian Forests with an Emphasis on T. multicolor Biosynthetic Potential.

In this study, a wide diversity in lignin-modifying enzyme (LME) secretion by 11 Trametes spp. strains isolated from the forests of Georgia was revealed in their submerged cultivation in both synthetic and lignocellulose-based media. Among them, T. multicolor BCC 511 was distinguished by simultaneous production of laccase, manganese peroxidase (MnP), and lignin peroxidase (LiP) in the presence of high carbon and nitrogen concentrations. Mannitol at the concentration of 15 g/L provided an accumulation of 23.7 U/mL laccase and 0.56 U/mL MnP. Significant modulation of LME activity by lignocellulosic substrates, metals, aromatic compounds, and their concentrations was established. Mandarin peels manifold increased the fungus laccase and LiP activities, while the ethanol production residue and banana peels activated manganese-oxidizing and Phenol Red-oxidizing manganese peroxidases, respectively. The addition of 2 mM of copper sulfate to the control medium induced the laccase production 28-fold and did not significantly affect the MnP and LiP activities. Fe2+ at a concentration of 0.1 mM enhanced the fungus volumetric and specific laccase activities almost 8-fold; at a concentration of 0.25-0.5 mM, there was a 2-fold increase in the MnP activity. Mn2+ appeared to be an effective inducer of the Mn-oxidizing MnP, increasing specific activity of the enzyme 14-fold. Supplementation of the copper-containing medium with 1 mM veratryl alcohol or guaiacol favored laccase and MnP production. The high yields of laccase (110 U/mL), MnP (0.62 U/mL), and LiP (0.71 U/mL) obtained in a laboratory fermenter make T. multicolor 511 useful for industrial and environmental applications.

Characterization and compositional analysis of agricultural crops and residues for ethanol production in California

This study was carried out in order to analyze characteristic and composition of crops, crop wastes, and residues including a variety of sugar beets and melons, tomato, Jose tall wheatgrass, wheat hay, and wheat straw in California. Ethanol potential was estimated from different scenarios in using carbon sources of feedstock during fermentation, including the new information of using pectin–derived galacturonic acid for ethanol production. Sugar beet appears more favorable than other feedstocks because of its high sugar content (67–75% dry basis, db) and the highest crop yield, resulting in the greatest ethanol potential of 591 m3 Gg−1 db when all carbohydrates are used during fermentation, with the California area–based potential of 1273 m3 km−2. Fermentation of polygalacturonic acid can increase the ethanol potential of sugar beet leaves up to 30% over the fermentation of hexoses alone, increasing the theoretical ethanol potential to 340 m3 Gg−1 and the area–based yield of 497 m3 km−2. Melons and tomato containing 42–69% by mass of soluble sugars showed ethanol potentials in a range of 448–545 m3 Gg−1 db and the area–based yield of 25–53 m3 km−2. The theoretical ethanol yield from lignocellulosic feedstocks tested can be maximized up to 470–533 m3 Gg−1 db and 291–300 m3 km−2 when the primary components from cellulose (27–39% db) and hemicellulose (26–30% db) are utilized. The information on composition and ethanol potential is important for determining biofuel feedstock and developing technology for efficient use of bioresource.

Pretreatment of sugarcane top leaves by ozonation as a promotion of susceptibility to hidrolysis

Studies about Ozone (O 3 ) application in sugarcane residues for ethanol production are ongoing. This study was undertaken to evaluate the use of ozone as a pretreatment to facilitate hydrolysis of sugarcane top leaves. In the first experimentation, sugarcane top leaves were subjected to ozone (62.37 mg O 3 min -1 over a three hour period) and water only (control). Following ozonation, the material was separated into a liquid and solid fraction. The analysis of liquid fraction showed that phenolic concentration and soluble solids did not vary. However, there was a decrease in pH and an increase in reducing sugars. This treatment increased saccharification. During the second treatment, ozone was added by direct infusion in a suspension of sugarcane top leaves and distilled water at a ratio of 1:10 (w.v -1 ). Additionally, the lignocellulosic analysis showed a positive relationship between the dose of ozone and decomposition of lignin and an increase in the proportion of cellulose and hemicellulose in the material. All aspects are good signs for the use of ozone in pretreatment of lignocelullosic feedstocks.

Substract and temperature effect on xylanase production by aspergillus fumigatus using low cost agricultural wastes

This study reports the optimization of xylanase production under solid state fermentation (SSF) by a thermotolerant Aspergillus fumigatus strain (SCB4) isolated from sugarcane bagasse piles of Brazilian Cerrado. Different combinations of low-cost agricultural byproducts in SSF were evaluated: sugarcane bagasse and wheat bran (1:1), sugarcane bagasse and corn straw (1:1) and only sugarcane bagasse. The enzyme biosynthesis by SSF was carried out at different temperatures (40, 45, 50 and 55 o C). The maximum levels of xylanase activity were obtained after 24 h at 45 °C using a culture medium containing sugarcane bagasse and wheat bran (1:1). Under optimal conditions, the fungal culture produced 574 U g -1 of xylanase (units/g of dry substrate). The crude enzyme showed optimal activity at 60 °C and pH 4.5. It exhibited thermostability up to 55 °C, wide range of pH stability and tolerance to ethanol, xylose and glucose. The physicochemical properties shown by this enzyme are appropriate for its application in hydrolysis of lignocellulosic residues for ethanol production and other bioproducts.

Comparative Evaluation of Three Sugarcane Supply Strategies in Colombia: Logistics, Energy and GHG Emissions

Sugarcane-based ethanol in Colombia has a prospective opportunity to explore the production of ethanol from lignocellulosic biomass taking into account that a large amount of generated residues (between 50 and 100 t/ha) are left on the field after green harvesting. The use of sugarcane green harvesting residues for ethanol production could be considered as a feasible solution but it is facing high supply costs. A bottom-up engineering cost model was used to estimate the green harvesting residues supply cost for three collection strategies. The model took into account the investment and operation costs of the residues collection, processing, delivery, and machineries including depreciations, repair and maintenance, and labor cost. Overall energy consumptions and life-cycle GHG emissions of the three strategies were analyzed. The integral harvesting showed the best performance in costs (6.01 USD/dry-t), energy consumptions (125.32 MJ/dry-t), and GHG emissions (7.74 kg CO2-eq/dry-t), followed by the baled and chopped residues.

Exploring soil microbial 16S rRNA sequence data to increase carbon yield and nitrogen efficiency of a bioenergy crop

AbstractCrop residues returned to the soil are important for the preservation of soil quality, health, and biodiversity, and they increase agriculture sustainability by recycling nutrients. Sugarcane is a bioenergy crop that produces huge amounts of straw (also known as trash) every year. In addition to straw, the ethanol industry also generates large volumes of vinasse, a liquid residue of ethanol production, which is recycled in sugarcane fields as fertilizer. However, both straw and vinasse have an impact on N2O fluxes from the soil. Nitrous oxide is a greenhouse gas that is a primary concern in biofuel sustainability. Because bacteria and archaea are the main drivers of N redox processes in soil, in this study we propose the identification of taxa related with N2O fluxes by combining functional responses (N2O release) and the abundance of these microorganisms in soil. Using a large‐scale in situ experiment with ten treatments, an intensive gas monitoring approach, high‐throughput sequencing of soil microbial 16S rRNA gene and powerful statistical methods, we identified microbes related to N2O fluxes in soil with sugarcane crops. In addition to the classical denitrifiers, we identified taxa within the phylum Firmicutes and mostly uncharacterized taxa recently described as important drivers of N2O consumption. Treatments with straw and vinasse also allowed the identification of taxa with potential biotechnological properties that might improve the sustainability of bioethanol by increasing C yields and improving N efficiency in sugarcane fields.

Sugar cane vinasse in water bodies: Impact assessed by liver histopathology in tilapia

Aquatic ecosystems are the main receptors of toxic substances from human activities. With the increase in sugar cane production, vinasse – the main residue of ethanol production – is a potential contaminant of water resources, due to its high organic matter content. This study was aimed at evaluating the toxicity of vinasse by examining the liver of the fish Oreochromis niloticus exposed to different dilutions of sugar cane vinasse (1%, 2%, 5%, 5% and 10%) in laboratory bioassays. Portions of liver were collected and fixed for histological and histochemical techniques to detect total proteins, polysaccharides and lipids. In the histological analysis, the groups treated with vinasse exhibited significant alterations, such as loss of cytoplasmic integrity, loss of cell limit and tissue disorganization. Protein and lipid profiles were not altered. Higher accumulation of polysaccharides was detected in fish exposed to lower concentrations of vinasse, with a gradual decrease in animals treated with vinasse in higher concentrations. We concluded that vinasse has a dose-dependent toxic and cytotoxic potential in water bodies and that the liver is strongly affected when acutely exposed to this contaminant.

Modulation of Cerrena unicolor laccase and manganese peroxidase production.

Among seven carbon sources tested, glycerol and glucose favored the Cerrena unicolor laccase production (18.8-20.3 U/mL); in addition, glycerol ensured the highest manganese peroxidase (MnP) activity (2 U/mL). Substitution of glycerol with the ethanol production residue (EPR) gave the highest laccase (90.1 U/mL) activity, while the walnut pericarp provided the highest MnP activity (7.4 U/mL). Supplementation of medium with 1 mM copper and 1 mM xylidine at appropriate time caused significant additive effect on laccase expression (333.2 U/mL) in shake-flask experiments. Overproduction of laccase activity (507 U/mL) and secretion of MnP activity was obtained when C. unicolor was cultivated in stirred-tank fermenter. C. unicolor showed several distinctive and attractive technological features: it is capable to synthesize high levels of oxidases under high carbon and high nitrogen conditions and it secretes high laccase activity during trophophase.

Alkaline and alkaline peroxide pretreatments at mild temperature to enhance enzymatic hydrolysis of rice hulls and straw

The current study explores alkaline and alkaline peroxide pretreatments in order to achieve a method to improve saccharification of agricultural residues for ethanol production. The effects of reagent concentration and pretreatment time at 30°C and atmospheric pressure on biomass dissolution after the pretreatment and enzymatic hydrolysis of the pretreated biomass were investigated. In fact, although all pretreatments tested improved enzymatic hydrolysis of native residues, the best results were not achieved for the highest biomass loss. The maximum conversions to reducing sugars in the hydrolysis stage of 77.5% and 92.6% were obtained for rice hulls and straw pretreated by alkaline peroxide (4%, 24h) and alkaline (1%, 48h) methods, respectively. For both pretreated residues, the reduction to more than half the recommended enzyme loading allowed obtaining more than 94% the reducing sugars attained with the recommended dose.

Características nutricionais e utilização do resíduo de batata-doce em dietas de frangos de crescimento lento

Foram realizados três experimentos, para determinar o valor energético e nutricional do resíduo da produção de etanol a partir da batata-doce (RBD) e a sua utilização em dietas para frangos de crescimento lento. No primeiro experimento foi realizado um ensaio metabólico a fim de determinar a energia metabolizável aparente (EMA) e a corrigida para o balanço de nitrogênio (EMAn), bem como os coeficientes de metabolizabilidade aparente do resíduo, utilizando o método de coleta total de excretas, num delineamento inteiramente casualizado, com dois tratamentos: ração referência e ração teste (70% ração referência + 30% de inclusão do resíduo da batata-doce), quatro repetições e dez frangos de crescimento lento por unidade experimental. O RBD apresentou: 24,64% de proteína bruta, 2732kcal/kg e 2547kcal/kg EMA e EMAn na matéria natural. Os demais experimentos foram realizados para avaliar níveis de inclusão (0%, 6%, 12% e 18%) do RBD em dietas de aves de crescimento lento, em um delineamento inteiramente casualizado, com quatro tratamentos e cinco repetições e 10 aves por unidade experimental, avaliando o desempenho e metabolismo das rações. Os níveis de inclusão não afetaram o consumo de ração, mas houve redução no ganho de peso (GP) e piora na conversão alimentar (CA). Os coeficientes de metabolizabilidade do nitrogênio e matéria mineral apresentaram efeito quadrático com pontos máximos de 6,38% e 5,17% respectivamente. O RBD pode ser incluído nas rações de aves de crescimento lento até o nível de 1,041%.

Evaluation of the tolerance of acetic acid and 2-furaldehyde on the growth of Pichia stipitis and its respiratory deficient

The use of lignocellulosic residues for ethanol production is limited by toxic compounds in fermenting yeasts present in diluted acid hydrolysates like acetic acid and 2-furaldehyde. The respiratory deficient phenotype gives the cell the ability to resist several toxic compounds. So the aim of this work was to evaluate the tolerance to toxic compounds present in lignocellulosic hydrolysates like acetic acid and 2-furaldehyde in Pichia stipitis and its respiratory deficient strains. The respiratory deficient phenotype was induced by exposure to chemical agents such as acriflavine, acrylamide and rhodamine; 23 strains were obtained. The selection criterion was based on increasing specific ethanol yield (gethanolg(-1)biomass) with acetic acid and furaldehyde tolerance. The screening showed that P. stipitis NRRL Y-7124 ACL 2-1RD (lacking cytochrome c), obtained using acrylamide, presented the highest specific ethanol production rate (1.82gg(-1)h(-1)). Meanwhile, the ACF8-3RD strain showed the highest acetic acid tolerance (7.80gL(-1)) and the RHO2-3RD strain was able to tolerate up to 1.5gL(-1) 2-furaldehyde with a growth and ethanol production inhibition of 23 and 22%, respectively. The use of respiratory deficient yeast phenotype is a strategy for ethanol production improvement in a medium with toxic compounds such as hydrolysed sugarcane bagasse amongst others.

Supercritical water gasification of ethanol production waste over graphite supported ruthenium catalyst

Supercritical water gasification of ethanol production residue from eucalyptus powder was studied over a graphite-supported 5wt% ruthenium catalyst (Ru/G) in a batch reaction system. The complete gasification of 0.1g of the residue proceeded over 0.05g of Ru/G at 673K in supercritical water with 0.5gcm−3 water density. The gasification behavior of the residue from eucalyptus was compared with that from Japanese cedar to evaluate the potential of fuel gas production from bioethanol production residue. The gasification profiles (gaseous yield and selectivity) of the resides were well reproduced by the linear combination of those of woody biomass fractions (lignin and cellulose).

Olive tree pruning as an agricultural residue for ethanol production. Fermentation of hydrolysates from dilute acid pretreatment

The use of agricultural residues for ethanol production constitutes one of the most promising alternatives from an environmental point of view for substituting fossil fuels in the transport sector. This work deals with the fermentability of hydrolysates obtained from olive tree pruning biomass and the influence of the pH of the culture medium. Hydrolysates of olive tree biomass were obtained by dilute acid pre-treatment of the raw material at 180ºC and 1% (w/v) sulfuric acid concentration. After pretreatment, solid residue and liquid were separated by filtration. The liquid fraction (hydrolysate) was then submitted to detoxification (overliming) before being used as fermentation medium. Pichia stipitis and Pachysolen tannophilus were compared as fermenting microorganisms. Different initial pH values were also tested. The best results in terms of ethanol yield were obtained by P. tannophilus with values as high as 0.44 g ethanol g-1 sugar, and all liquids were fermented, to a different extent. P. stipitis could not ferment hydrolysates with initial pH below 6.5. It was also determined that ethanol production did not improve once glucose in the medium was totally converted, even if other sugars (xylose) were also consumed.