hydrothermal pretreatment

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The effect of pretreatment methods for improved biodegradability and biogas production of oil palm empty fruit bunches (EFB) and its co-digestion with palm oil mill effluent (POME) was investigated. The maximum methane potential of POME was 502 mL CH 4 /g VS-added corresponding to 33.2 m 3 CH 4 /ton POME and 98% biodegradability. Meanwhile, the maximum methane potential of EFB was 202 mL CH 4 /g VS-added corresponding to 79.1 m 3 CH 4 /ton EFB with 38% biodegradability. Co-digestion of EFB with POME enhanced microbial biodegradability and resulted in 25-32% higher methane production at mixing ratios of 0.4:1, 0.8:1 and 2.3:1 on VS basis than digesting EFB alone. The methane yield was 276-340 mL CH 4 /g VS-added for co-digestion of EFB with POME at mixing ratios of 0.4:1-2.3:1, while minor improvement was observed at mixing ratios of 6.8:1 and 11:1 (175-197 mL CH 4 /g VS-added). The best improved was achieved from co-digestion of treated EFB by NaOH presoaking and hydrothermal treatment with POME, which resulted in 98% improvement in methane yield comparing with co-digesting untreated EFB. The maximum methane production of co-digestion treated EFB with POME was 82.7 m 3 CH 4 /ton of mixed treated EFB and POME (6.8:1), corresponding to methane yield of 392 mL CH 4 /g VS-added. The electricity production of 1 ton mixture of treated EFB and POME would be 1190 MJ or 330 kW h of electricity. The study shows that there is a great potential to co-digestion treated EFB with POME for bioenergy production.

The aim of the present work was to determine the optimum operating conditions in hydrothermal pretreatments applied to canola seeds. The effect of these pretreatments on the canola oil extraction yield and quality was evaluated. Samples were characterized by proximate analysis. Acidity and peroxide value were studied as parameters for the determination of oil quality. Seeds were exposed to direct steam contact in an autoclave. Pretreatments were carried out using different temperatures (100, 120 and 130 8C), exposition times (5, 15 and 30 min) and seed granulometry (ground seeds, with a particle size in a range from 0.420 to 1.000 mm; broken seeds, with a particle size ranging from 1.000 to 1.410 mm, and entire seeds). After each hydrothermal pretreatment, oil extraction was carried out by the Soxhlet method (hexane). The Taguchi method was followed in order to explore the optimum operating conditions by using an L9 experimental design, and select the most favourable levels of each variable. Initial oil content was 44.2% dry basis (db). The selected optimum experiment, using a temperature of 120 8C, a time of 5 min and broken seeds, generated an oil yield increase of 20% compared with non-hydrothermally treated seeds, whereas quality parameters remained within the accepted values for trade standards.

In search to increase the offer of liquid, clean, renewable and sustainable energy in the world energy matrix, the use of lignocellulosic materials (LCMs) for bioethanol production arises as a valuable alternative. The objective of this work was to analyze and compare the performance of Saccharomyces cerevisiae, Pichia stipitis and Zymomonas mobilis in the production of bioethanol from coconut fibre mature (CFM) using different strategies: simultaneous saccharification and fermentation (SSF) and semisimultaneous saccharification and fermentation (SSSF). The CFM was pretreated by hydrothermal pretreatment catalyzed with sodium hydroxide (HPCSH). The pretreated CFM was characterized by X-ray diffractometry and SEM, and the lignin recovered in the liquid phase by FTIR and TGA. After the HPCSH pretreatment (2.5% (v/v) sodium hydroxide at 180 C for 30 min), the cellulose content was 56.44%, while the hemicellulose and lignin were reduced 69.04% and 89.13%, respectively. Following pretreatment, the obtained cellulosic fraction was submitted to SSF and SSSF. Pichia stipitis allowed for the highest ethanol yield e 90.18% e in SSSF, 91.17% and 91.03% were obtained with Saccharomyces cerevisiae and Zymomonas mobilis, respectively. It may be concluded that the selection of the most efficient microorganism for the obtention of high bioethanol production yields from cellulose pretreated by HPCSH depends on the operational strategy used and this pretreatment is an interesting alternative for add value of coconut fibre mature compounds (lignin, phenolics) being in accordance with the biorefinery concept.

Low-carbon circular economy strategies within the whiskey industry necessitate minimal use of fossilbased energy including heat and electricity. Renewable energy generated from process by-products such as draff and pot ale offers opportunities for circular bioeconomy systems. However, such a system is yet to be defined and assessed in detail. In this study, biological valorization (dark hydrogen fermentation and anaerobic digestion) of whiskey by-products was comparatively evaluated in terms of fundamental principles and thermodynamics of biochemical reactions. Four scenarios based on a whiskey plant size of 2 million L/a were evaluated to determine the potential energy recovery (in the form of electricity and heat) and CO 2 emissions reduction. The recommended scenario with anaerobic digestion of pretreated by-products resulted in a biogas production of 1.72 million m 3 (containing 1.03 million m 3 biomethane, corresponding to an energy yield of 10,300 MWh). If the produced biogas is used for producing heat and electricity in a combined heat and power system, 446% of the annual electricity demand (740 MW e h) and 25% of the heat demand (4,230 MW th h) of the traditional distillery can be covered, leading to a reduction in energy related CO 2 emissions of 61% from whiskey production (2,300 ton CO 2). Preliminary economic analysis shows that the proposed system has an annual net income of V741,176 with a payback period of 3.94 years. Net present value of the system is V4,933,456 with a discounted payback period of 4.77 years. Future research on a detailed techno-economic feasibility and life cycle assessment of such a system should be investigated before practical implementation.

The effect of a hydrothermal pretreatment on the solvent extraction of oil and minor compounds (tocopherols) from high stearic high oleic sunflower seeds (HSHO), partially dehulled and undehulled, was analyzed. Samples of sunflower seeds of different origins and oil contents (high oil, 43.0% d.b., and low oil 35.1% d.b.) were used. The oil yield increased significantly due to the hydrothermal pretreatment (p ≤ 0.05) for HSHO samples with high oil content, both partially dehulled and undehulled. The pretreated HSHO samples with low oil content did not show significant differences in oil yield compared to the untreated samples. The effective diffusion coefficients for the hydrothermally pretreated seeds (2.12.10 −11 m 2 s −1) and the untreated samples (7.07.10 −12 m 2 s −1) were determined based on the oil extraction from the partially dehulled high oil HSHO samples. For both types of partially dehulled HSHO seeds, a significant increase in tocopherol content in the oils extracted from the pretreated samples was observed.

The effect of the combined hydrothermal-microwave (HT-MW) pretreatment operating conditions on the oil extraction yield by cold pressing was evaluated, as well as its canolol and tocopherols content. Entire and broken canola seeds were subjected to hydrothermal pretreatment at different temperatures (110°C and 130°C), then they were irradiated in a microwave oven until reaching a moisture content of 6.5% (dry basis), that it is a safe storage moisture and it is adequate for the pressing process. Entire seeds exposed at a HT temperature of 130°C and microwaved for 2.98 min exhibited the best canola oil expression yield (34.9%, d.b) and the highest amount of canolol (533 µg/g oil), maintaining the total tocopherol content invariant with respect to oil from samples subjected to the other pretreatment operating conditions and from untreated seeds. However, individual tocopherol isomers presented different contents when varying pretreatment conditions, showing a differential extraction due to the factors analysed (seeds granulometry/breakage and HT temperature). At the optimum conditions quality as means of acidity, peroxide index and p-Anisidine value were determined. Acidity index slightly increased due to the pretreatment and peroxide index significantly diminished, being both value below the limits preestablished by the Alimentarius Codex. Meanwhile, p-Anisidine value notably increased, slightly affecting TOTOX value.

In order to identify the effects of different chemical pretreatment methods on structure changes of corncobs and their subsequent pyrolysis characteristics, the chemical pretreatment of corncobs was performed using different concentrations of sodium hydroxide (NaOH), sulfuric acid (H 2 SO 4), and hydrogen peroxide (H 2 O 2) solutions. The structure changes of corncobs were characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). The pyrolysis characteristics of raw and pretreated corncobs were conducted on thermogravimetric analyzer (TGA) and pyrolysisegas chromatography/mass spectrometry (PyeGC/MS). TG/DTG analysis of raw and pretreated corncobs demonstrated that the rank order for the ease of pyrolysis was untreated < 1% NaOH < 1% H 2 O 2 < 2% NaOH < 2% H 2 SO 4 < 1% H 2 SO 4. PyeGC/MS analysis showed that chemical pretreatment can effectively promote the production of furans and levoglucosan (LG) and inhibit the formation of acetic acid, ketones and phenols. The rank order of LG yields from untreated and pretreated corncobs was untreated < 1% NaOH < 2% NaOH < 1% H 2 O 2 < 1% H 2 SO 4 < 2% H 2 SO 4. The maximum yield of LG (15.01%) was obtained by fast pyrolysis of corncobs pretreated using 2% H 2 SO 4. It was 18.53 times the yield of LG from untreated corncobs. The results could be mainly attributed to the passivation of alkali metal and alkali earth metal and the removal of hemicellulose and lignin fractions during pretreatment.

Residual banana bulbs (RBB) were characterized and assessed as a potential starch and cellulose-based feedstock for bioethanol production. To facilitate the enzymatic digestibility, hydrothermal pretreatment was performed on RBB prior to simultaneous saccharification and fermentation (SSF) with Saccharomyces cerevisiae. Composition of RBB was similar to traditional starch and cellulose-based feedstocks with high glucan (60 g/100 gDM) and relatively low lignin content (7 g/100 gDM). Both amylase and cellulase were needed to efficiently hydrolyze RBB. The highest ethanol yield (310 kg EtOH/ton_DM_RBB, 93% of theoretical production based on total available glucose) was obtained with non-pretreated RBB. SSF can be carried out at lower RBB concentrations. Hydrothermal pretreatment affected negatively the bioethanol potential due to the loss of fermentable carbohydrates. In a case study of an African leading producer of bananas and plantains (Cameroon), the energy derived from bioethanol was 80 GWh ethanol/year and corresponded to 1.6% of the annual transportation requirement. This study shows that RBB is a promising alternative feedstock for bioethanol production.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The effect of the combined hydrothermal-microwave (HT-MW) pretreatment operating conditions on the oil extraction yield by cold pressing was evaluated, as well as its canolol and tocopherols content. Entire and broken canola seeds were subjected to hydrothermal pretreatment at different temperatures (110°C and 130°C), then they were irradiated in a microwave oven until reaching a moisture content of 6.5% (dry basis), that it is a safe storage moisture and it is adequate for the pressing process. Entire seeds exposed at a HT temperature of 130°C and microwaved for 2.98 min exhibited the best canola oil expression yield (34.9%, d.b) and the highest amount of canolol (533 μg/g oil), maintaining the total tocopherol content invariant with respect to oil from samples subjected to the other pretreatment operating conditions and from untreated seeds. However, individual tocopherol isomers presented different contents when varying pretreatment conditions, showing a differential extraction d...

The aim of the present work was to determine the optimum operating conditions in hydrothermal pretreatments applied to canola seeds. The effect of these pretreatments on the canola oil extraction yield and quality was evaluated. Samples were characterized by proximate analysis. Acidity and peroxide value were studied as parameters for the determination of oil quality. Seeds were exposed to direct steam contact in an autoclave. Pretreatments were carried out using different temperatures (100, 120 and 130 8C), exposition times (5, 15 and 30 min) and seed granulometry (ground seeds, with a particle size in a range from 0.420 to 1.000 mm; broken seeds, with a particle size ranging from 1.000 to 1.410 mm, and entire seeds). After each hydrothermal pretreatment, oil extraction was carried out by the Soxhlet method (hexane). The Taguchi method was followed in order to explore the optimum operating conditions by using an L9 experimental design, and select the most favourable levels of each variable. Initial oil content was 44.2% dry basis (db). The selected optimum experiment, using a temperature of 120 8C, a time of 5 min and broken seeds, generated an oil yield increase of 20% compared with non-hydrothermally treated seeds, whereas quality parameters remained within the accepted values for trade standards.

Η παγκόσμια κατανάλωση ενέργειας προβλέπεται να αυξηθεί περίπου 35% για την περίοδο 2010-2040 ενώ για την ίδια περίοδο ο παγκόσμιος πληθυσμός θα φτάσει τα 9 δις ανθρώπους. Σήμερα οι αυξημένες ενεργειακές ανάγκες συνεχίζουν να καλύπτονται κυρίως από τα ορυκτά καύσιμα (μη ανανεώσιμες πηγές ενέργειας). Η μείωση των αποθεμάτων των ορυκτών καυσίμων, το αυξημένο κόστος εξόρυξής τους καθώς και οι δυσμενείς επιπτώσεις στο περιβάλλον εξαιτίας των αυξημένων εκπομπών CO2, οδηγούν στην ανεύρεση άλλων πηγών ενέργειας όπως είναι οι ανανεώσιμες. Η λιγνοκυτταρινούχα βιομάζα, η οποία αποτελείται από τρία βασικά δομικά συστατικά, την κυτταρίνη, τις ημικυτταρίνες και τη λιγνίνη, αποτελεί μια υποσχόμενη ανανεώσιμη πηγή για την παραγωγή ενέργειας, βιοκαυσίμων και χημικών ενώσεων υψηλής προστιθέμενης αξίας. Μια από τις βασικές διεργασίες για την αξιοποίηση της λιγνοκυτταρινούχας βιομάζας είναι η βιοχημική οδός, όπου μέσω των σταδίων της προεπεξεργασίας της βιομάζας, της ενζυμικής υδρόλυσης της κυτταρίνης...