Carolina Parra

Characterization of white zones produced on Pinus radiata wood chips by Ganoderma australe and Ceriporiopsis subvermispora

White zones produced on biodegraded Pinus radiata wood chips were characterized by micro-localized-FTIR (Fourier Transformed Infra Red) spectroscopy and scanning electron microscopy. Both techniques permitted assignment of the white zones to a selective lignin removal process. Although both fungi studied have degraded lignin selectively in these restricted superficial areas, chemical analysis of the wood chips indicated that Ganoderma australe removed 16% of the initial amount of glucan at the 20% weight loss level. Ceriporiopsis subvermispora did not remove glucan at weight loss values below 17%. Prolonged biodegradation resulted in reduction of white zones by G. australe, and increased white zones from C. subvermispora decayed samples.

Occurrence of iron-reducing compounds in biodelignified “palo podrido” wood samples

Abstract Palo podrido (literally, rotted log) and iron chelating compounds associated with it were characterized. Field-collected samples taken from palo podrido were sorted visually into three groups representing early, and two stages of advanced delignification (termed as EDS, ADS1 and ADS2, respectively). Lignin contents in these samples were 22.3%, 5.1% and 4.6%, respectively. Ethyl acetate extracts from ADS1 and ADS2 samples contained several aromatic carboxylic acids. Dihydroxyterephtalic acid was detected as the major compound in ADS1 extract and was found at low concentrations in ADS2 extract. Only the ADS1 extract exhibited a significant iron reduction activity, reducing 3.1% of an initial 500 μM Fe 3+ solution after the first minute of reaction. After 10 min reaction, 9.5% of the initial Fe3+ was reduced. Reduction activity expressed on the basis of extracted dry mass of ADS1 was 12.5 μmol of Fe3+ reduced/min/kg of dry wood.

Biodegradation of Chilean native wood species, Drimys winteri and Nothofagus dombeyi, by Ganoderma australe

Drimys winteri and Nothofagus dombeyi, two native Chilean wood species with high potential for pulp production, were biodegraded by Ganoderma australe. This fungus is known to provoke extensive and selective biodelignification of these wood species in the field. Under laboratory conditions, N. dombeyi underwent higher weight and component losses than D. winteri. In neither case was the lignin removal selective, because glucan loss was almost simultaneous with lignin degradation. The decayed wood chips became progressively discoloured throughout the biodegradation time. The brightness increase was only partly reversed in thermal reversion assays. Nothofagus dombey solubility in 1% NaOH increased by 13.7% after 9 weeks of biodegradation, while D. winteri solubility increased by 14.2% in a shorter period (6 weeks). In both cases, the solubility increase was proportional to the liquor absorbance increase at 272 nm, which indicates that the wood solubility in 1% NaOH was dependent of lignin solubilization.

β-Glucosidase immobilisation on synthetic superparamagnetic magnetite nanoparticles and their application in saccharification of wheat straw and Eucalyptus globulus pulps

β-Glucosidase from Trichoderma reesei was immobilised on synthetic superparamagnetic magnetite (Fe3O4) nanoparticles with a mean diameter of 10 nm and were used to supplement cellulase in the enzymatic hydrolysis of three substrates: wheat straw pretreated by steam explosion, Eucalyptus globulus pretreated by hydrothermolysis and E. globulus pretreated by hydrothermolysis followed by alkaline extraction. The hydrolysis yields for each pretreated material, using immobilised β-glucosidase (I-βG) and free cellulase, were 76.1%, 83.6% and 75.6%, respectively, and resulted in an improved hydrolysis yields compared with only cellulase. These yields were at most 10% lower than yields reached with free enzymes. The (I-βG) was magnetically recovered and successfully reused twice. The differences in the hydrolysis yields were not significant (p > 0.05) in the case of steam-exploded wheat straw and E. globulus pretreated by hydrothermolysis followed by alkaline extraction. The immobilisation of enzymes provides an opportunity to reduce the costs of enzymes in the bioethanol production process.

Pilot Plant Design and Operation Using a Hydrothermal Pretreatment: Bioenercel Experience

Over the last century, the world has depended on the oil industry to provide the greatest majority of the raw material necessary for the production of chemical products, textiles, pharmaceuticals, and fuels. Countries with no oil reserves have the necessity to seek new cleaner and sustainable technologies to fulfill its requirements. Lignocellulosic biomass has the potential to replace oil as the raw material to produce chemicals and fuels under a biorefinery concept. To develop this new concept of industry, Bioenercel, a Chilean Consortium, was created to design a strategy to obtain sugars and lignin from wood as raw materials for the production of fuels and high-value products: bioethanol or bio-oil production from sugar fermentation and generation of biomaterials from lignin. This strategy includes a pilot plant design and operation. The plant was designed to handle a variety of feedstocks; the process stages are batched to optimize each step individually and the process as a whole. It also considers a wide range of operation options for process flexibility. The equipment includes a wood digester for biomass pretreatment, a disc refiner, a high consistency horizontal mixer (pre-hydrolyzer) and a hydrolyzer for the enzymatic hydrolysis, a fermenter, and a distillation column. Pre-hydrolyzer, hydrolyzer, and fermenter are combined with a filter press to adjust the operation to a simultaneous saccharification and fermentation process or to a separate hydrolysis and fermentation process. Additionally, all the complimentary equipment is in place for this pilot plant to successfully mimic a biorefinery. This work shows a pilot plant experience using hardwood (eucalyptus wood) to obtain ethanol using autohydrolysis pretreatment and simultaneous saccharification and fermentation with high solid loads.

NIR SPECTROSCOPY APPLIED TO THE CHARACTERIZATION AND SELECTION OF PRE-TREATED MATERIALS FROM MULTIPLE LIGNOCELLULOSIC RESOURCES FOR BIOETHANOL PRODUCTION

Lignocellulosic biomass (LB) has been recognized as potential raw for bioethanol production. To facility LB bioconversion a pretreatment is applied, followed by simultaneous or separated saccharification and fermentation (SSF or SHF, respectively) steps. Characterization of pretreated materials, needed to evaluate their ethanol yields, involves laborious and destructive methodologies. Therefore, saccharification is also time consuming and expensive step and some pretreated samples have not suitable characteristics to obtain high ethanol yields. Since bioethanol production aims to be a multivariable process respect to lignocellulosic resources, this work attempts to use NIR spectroscopy as alternative to wet chemical analysis to characterize samples from multiple pretreatments and lignocellulosic resources simultaneously and estimate their ethanol yield after a SSF process using multivariate calibration. Selection of suitable samples to obtain high ethanol yields using a classification method is also evaluated. Partial least squares (PLS) and discriminant partial least squares (PLS-DA) were used as calibration and classification techniques, respectively. Results showed ability of NIR spectroscopy to predict the chemical composition of samples and their ethanol yields, even if different lignocellulosic materials were used in the models, with low prediction errors and high correlation coefficients with reference methods (r>0,96) in PLS models and low misclassification rates (20- 30%) in classification models. Use of these models could facility the fast selection of high number of samples with suitable characteristics to obtain high ethanol yields and as predictive tool of these ethanol yields after a SSF process under controlled conditions.

CHEMICAL AND MICROSTRUCTURAL CHANGES IN EUCALYPTUS GLOBULUS FIBERS SUBJECTED TO FOUR DIFFERENT PRETREATMENTS AND THEIR INFLUENCE ON THE ENZYMATIC HYDROLYSIS

In order to understand the relation between chemical composition, microscopic structure and enzymatic digestibility, different Eucalyptus globulus Wood pretreated samples were examined. Pretreated materials obtained by steam explosion and autohydrolysis were compared with those obtained by organosolv and kraft processes. Chemical analyses of pretreated materials showed a decrease in the content of xylans, except in the kraft pulp. FT-IR spectra showed that the residual lignin in autohydrolysis pulp had experienced greater changes compared to those in steam explosion and organosolv pulps, whereas minor changes in lignin kraft pulp were observed. The fiber morphology indicated that autohydrolysis pretreatment was the most aggressive treatment. Reduction in the content of lignin and its redistribution on the fiber wall were confirmed through confocal laser microscopy. The formation of discrete lignin droplets deposited on the surface of the fibers was observed in all pretreatments, with a higher frequency in organosolv followed by steam explosion. A significant increase in enzymatic accessibility was achieved in organosolv, autohydrolysis and steam explosion pulps, due to xylans removal combined with lignin redistribution. Homogeneous lignin distribution and higher xylan content may be related to the low enzymatic hydrolysis efficiency in kraft pulp.

BIOETHANOL POTENTIAL FROM HIGH DENSITY SHORT ROTATION WOODY CROPS ON MARGINAL LANDS IN CENTRAL CHILE

Cellulosic ethanol is one of the most important biotechnological products to mitigate the consumption of fossil fuels and to increase the use of renewable r...