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Effect of Maize Biomass Composition on the Optimization of Dilute-Acid Pretreatments and Enzymatic Saccharification
Torres Salvador, A.F. ; Weijde, R.T. van der; Dolstra, O. ; Visser, R.G.F. ; Trindade, L.M. - \ 2013
Bio Energy Research 6 (2013)3. - ISSN 1939-1234 - p. 1038 - 1051.
cell-wall composition - bicolor l. moench - cellulosic ethanol - corn stover - sulfuric-acid - lignocellulosic biomass - technoeconomic analysis - reduces recalcitrance - lignin biosynthesis - biofuel production
At the core of cellulosic ethanol research are innovations leading to reductions in the chemical and energetic stringency of thermochemical pretreatments and enzymatic saccharification. In this study, key compositional features of maize cell walls influencing the enzymatic conversion of biomass into fermentable sugars were identified. Stem samples from eight contrasting genotypes were subjected to a series of thermal dilute-acid pretreatments of increasing severity and evaluated for glucose release after enzymatic saccharification. The biochemically diverse set of genotypes displayed significant differences in glucose yields at all processing conditions evaluated. The results revealed that mechanisms controlling biomass conversion efficiency vary in relation to pretreatment severity. At highly severe pretreatments, cellulose conversion efficiency was primarily influenced by the inherent efficacy of the thermochemical process, and maximum glucose yields were obtained from cellulosic feedstocks harboring the highest cellulose contents per dry gram of biomass. When mild dilute-acid pretreatments were applied, however, maximum bioconversion efficiency and glucose yields were observed for genotypes combining high stem cellulose contents, reduced cell wall lignin and highly substituted hemicelluloses. For the best-performing genotype, glucose yields under sub-optimal processing regimes were only 10 % lower than the genotype-set mean at the most stringent processing conditions evaluated, while furfural production was reduced by approximately 95 %. Our results ultimately established that cellulosic feedstocks with tailored cell wall compositions can help reduce the chemical and energetic intensity of pretreatments used in the industry and improve the commercial and environmental performance of biomass-to-ethanol conversion technologies.
The summertime Boreal forest field measurement intensive (HUMPPA-COPEC-2010): an overview of meteorological and chemical influences
Williams, J. ; Crowley, J. ; Fischer, H. ; Harder, H. ; Martinez, M. ; Ouwersloot, H.G. ; Vilà-Guerau de Arellano, J. ; Ganzeveld, L.N. ; Lelieveld, J. - \ 2011
Atmospheric Chemistry and Physics 11 (2011)20. - ISSN 1680-7316 - p. 10599 - 10618.
volatile organic-compounds - gas chromatography/mass spectrometry - acid-water nucleation - tropical rain-forest - sulfuric-acid - scots pine - boundary-layer - natural aerosol - phase microextraction - atmospheric particles
This paper describes the background, instrumentation, goals, and the regional influences on the HUMPPACOPEC intensive field measurement campaign, conducted at the Boreal forest research station SMEAR II (Station for Measuring Ecosystem-Atmosphere Relation) in Hyyti¨al¨a, Finland from 12 July–12 August 2010. The prevailing meteorological conditions during the campaign are examined and contrasted with those of the past six years. Back trajectory analyses show that meteorological conditions at the site in 2010 were characterized by a higher proportion of southerly flow than in the other years studied. As a result the summer of 2010 was anomalously warm and high in ozone making the campaign relevant for the analysis of possible future climates. A comprehensive land use analysis, provided on both 5 and 50 km scales, shows that the main vegetation types surrounding the site on both the regional and local scales are: coniferous forest (Scots pine and/or Norway spruce); mixed forest (Birch and conifers); and woodland scrub (e.g. Willows, Aspen); indicating that the campaign results can be taken as representative of the Boreal forest ecosystem. In addition to the influence of biogenic emissions, the measurement site was occasionally impacted by sources other than vegetation. Specific tracers have been used here to identify the time periods when such sources have impacted the site namely: biomass burning (acetonitrile and CO), urban anthropogenic pollution (pentane and SO2) and the nearby Korkeakoski sawmill (enantiomeric ratio of chiral monoterpenes). None of these sources dominated the study period, allowing the Boreal forest summertime emissions to be assessed and contrasted with various other source signatures
The European aerosol budget in 2006
Brugh, J.M.J. Aan de; Schaap, M. ; Vignati, E. ; Dentener, F. ; Kahnert, M. ; Sofiev, M. ; Huijnen, V. ; Krol, M.C. - \ 2011
Atmospheric Chemistry and Physics 11 (2011)3. - ISSN 1680-7316 - p. 1117 - 1139.
general-circulation model - evaluation program emep - light absorbing carbon - air-pollution - sulfuric-acid - sea-salt - tropospheric aerosols - 3-dimensional model - size distributions - particulate matter
This paper presents the aerosol budget over Europe in 2006 calculated with the global transport model TM5 coupled to the size-resolved aerosol module M7. Comparison with ground observations indicates that the model reproduces the observed concentrations quite well with an expected slight underestimation of PM10 due to missing emissions (e.g. resuspension). We model that a little less than half of the anthropogenic aerosols emitted in Europe are exported and the rest is removed by deposition. The anthropogenic aerosols are removed mostly by rain (95%) and only 5% is removed by dry deposition. For the larger natural aerosols, especially sea salt, a larger fraction is removed by dry processes (sea salt: 70%, mineral dust: 35%). We model transport of aerosols in the jet stream in the higher atmosphere and an import of Sahara dust from the south at high altitudes. Comparison with optical measurements shows that the model reproduces the Ångström parameter very well, which indicates a correct simulation of the aerosol size distribution. However, we underestimate the aerosol optical depth. Because the surface concentrations are close to the observations, the shortage of aerosol in the model is probably at higher altitudes. We show that the discrepancies are mainly caused by an overestimation of wet-removal rates. To match the observations, the wet-removal rates have to be scaled down by a factor of about 5. In that case the modelled ground-level concentrations of sulphate and sea salt increase by 50% (which deteriorates the match), while other components stay roughly the same. Finally, it is shown that in particular events, improved fire emission estimates may significantly improve the ability of the model to simulate the aerosol optical depth. We stress that discrepancies in aerosol models can be adequately analysed if all models would provide (regional) aerosol budgets, as presented in the current study
Comparison of dilute mineral and organic acid pretreatment for enzymatic hydrolysis of wheat straw
Kootstra, A.M.J. ; Beeftink, H.H. ; Scott, E.L. ; Sanders, J.P.M. - \ 2009
Biochemical Engineering Journal 46 (2009)2. - ISSN 1369-703X - p. 126 - 131.
corn stover - hemicellulose hydrolysis - cellulose hydrolysis - high-temperature - sulfuric-acid - pig diets - d-xylose - ethanol - degradation - inhibitors
The efficiencies of fumaric, maleic, and sulfuric acid in wheat straw pretreatment were compared. As a measure for pretreatment efficiency, enzymatic digestibility of the lignocellulose was determined. Monomeric glucose and xylose concentrations were measured after subsequent enzymatic hydrolysis, as were levels of sugar degradation products furfural and hydroxymethylfurfural after pretreatment. The influence of pretreatment temperature and of wheat straw loading was studied. It is shown that, at 150 °C and 20–30% (w/w) dry wheat straw, the pretreatment with dilute fumaric or maleic acid can be a serious alternative to dilute sulfuric acid pretreatment