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The technical viability was investigated for the conversion of Pinus pinaster stumps to value-added products via a chain of pretreatments and simultaneous saccharification and fermentation (SSF) steps to obtain bioethanol. Sequential steam explosion (SE), organosolv (OS) pretreatment and soda-anthraquinone pulping (Na/AQ) were performed resulting in an unbleached pulp (UBP), which was successfully converted via SSF to bioethanol with concentrations up to 79 g l−1, which corresponds to a conversion yield of 97% and productivity of 1.09 g l−1 h−1 at 15% total solids. Accordingly, delignification steps by oxygen bleaching are not necessary for bioethanol production. Different industrial softwood (SW) pulps were also tested as reference materials. Total lignin contents up to 4.5% in SW-based pulps had no adverse effects on SSF efficiency.

The concept of bioeconomy has been promoted worldwide in order to replace fossil-based resources and to find new strategies for waste management, by converting biomass into energy, chemicals, and value-added products, in a sustainable way. Despite the efforts that have been made in this area, there are still some unexplored raw materials globally, namely from agricultural and forestry industries. Therefore, the aim of this work was to characterize four abundant residues from the Portuguese agroforestry industry, including pruning residues (pine branches, PB) and stumps (PS), tomato waste (TW), and winery wastewater (WW), for analyzing their potential within the biorefinery context. Volatiles were analyzed by gas-chromatography, and compounds with repellent/attractant properties were found for PB and PS, while flavor-enhancers were particularly identified in agrowastes. Composition analysis revealed that both TW and WW had the potential for biogas generation (BMP ∼340 and ∼250 NL CH4/kg VS, respectively), whereas forestry residues (PS and PB) can be recovered for thermal energy (HHV ∼20 MJ/kg) and bioethanol production (∼0.3−0.4 L/kg). Among all the aqueous extracts that were obtained, PS showed both the highest antioxidant activity (IC 50 ∼6 μg/mL) and total phenolic content (∼400 mg GAE/g extract). All residues were demonstrated to be promising for the Portuguese biobased economy.

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Primary sludge, from different pulp and paper mills, was used as feedstock in simultaneous saccharification and fermentation (SSF) processes to produce ethanol. SSF was carried out with Saccharomyces cerevisiae ATCC 26602 yeast and NS 22192 enzymatic extract using 150gL(-1) of carbohydrates (CH) from primary sludge. The effect of sterilization, reduction of enzyme dosage and fed-batch vs. batch conditions were studied. The removal of sterilization can be considered since no contamination or atypical by-products were observed, although SSF efficiency slightly decreased. The reduction of the enzyme dosage from 35 to 15FPUgCH(-1) was successful. Despite of initial mixing difficulties, batch SSF enabled higher ethanol concentration (41.7gL(-1)), conversion yield (48.9%) and productivity (0.78gL(-1)h(-1)), compared to the fed-batch process at the same conditions of low enzyme dosage of 5FPUgCH(-1) and high solids content of 21.7%, rarely found in literature.

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Primary sludge is a lignocellulosic residue from pulp and paper mills consisting of cellulosic fibers and ash. However, the high ash content (35%, mainly CaCO 3 ) and pH value affect the enzymatic hydrolysis of cellulosic fibers. Several pretreatments were used to reduce the CaCO 3 content and to adjust the pH. Enzymatic hydrolysis of primary sludge was enhanced when it was pretreated with HCl or spent acid (another residual stream of the same plant). Cellulosic fibers were converted to monomeric sugars by Cellic CTec2 cellulase with a dosage of 35 FPU g CH −1 for a carbohydrate concentration of 46 g L −1. This conversion was enhanced from 20% to 88% for primary sludge pretreated with HCl and to 72% for samples pretreated with spent acid. The fermentation of 27 g L −1 of available sugars with Pichia stipitis led to ethanol concentrations of up to 10.5 g L −1 with a yield of 0.39 g EtOH g sug −1 .

Article in press -uncorrected proof Prehydrolysis of Eucalyptus globulus Labill. hemicelluloses prior to pulping and fermentation of the hydrolysates with the yeast Pichia stipitis 10 th EWLP, AbstractThe aim of this work was to evaluate the potential of Eucalyptus globulus hemicelluloses, mainly xylan, for bioethanol production. Hemicelluloses have been removed prior to pulping by auto-hydrolysis and an acidcatalysed hydrolysis. As the hydrolysates obtained were rich in xylose, the yeast Pichia stipitis was selected for fermentation. It was confirmed that the yeast performance is strongly dependent on pH and the presence of inhibitors, such as lignin. The addition of Ca(OH) 2 was successful for lowering the concentration of inhibitors and adjusting the pH. The strain was grown in culture media with increasing volumetric percentages of treated hydrolysates up to 100% (v/v), supplemented with nutrients other than the carbon and energy source. This methodology shortened the lag phase of fermentation and improved the performance of yeast. Maximum ethanol concentration (12 g eth l -1 ), productivity (0.22 g eth l -1 h -1 ), and yield (0.48 g eth g xyl eqs -1 ) were achieved with treated acid-hydrolysates. These results are similar to those obtained by a synthetic medium with an equivalent xylose concentration.