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- Jet-loop reactor with cross-flow ultrafiltration membrane system for treatment of olive mill wastewaterPublication . Ribeiro, Belina; Torrado, Ivone; Di Berardino, Santino; Paixão, Susana M.; Rusan, M. J.; Amer, A. Bani; Zuraiqi, S.; Eusebio, AnaABSTRACT: Olive oil extraction is one of the ancient agricultural industries all over the Mediterranean area and even today it is of fundamental economic importance for many industries found over the whole Mediterranean. However, this industry generates large amounts of olive mill wastewater (OMW) and due to its physicochemical characteristics it causes severe environmental concerns and management problems in the Mediterranean area, which is facing water scarcity. Technologies to reuse this wastewater will have a high impact at the economic and environmental level. The work presented aims to improve the use of jet-loop reactors technology for the aerobic biotreatment of OMW. A jet-loop reactor (100 L) coupled with an ultrafiltration (UF) membrane (MBR) system (JACTO.MBR_100 L) were tested for the influence of hydraulic parameters on OMW degradation and scale-up to 1,000 L. Chemical oxygen demand and total phenols (TP) decreased notably (up to 85% and 80% removal efficiency, respectively) after the biological treatment. The treated OMW (UF permeate) was evaluated as a source for irrigation and its impact on the soil and plant growth and their quality parameters.
- Production of Oligosaccharides from Pine Nut Shells by AutohydrolysisPublication . Torrado, Ivone; Dionísio, Ana; Fernandes, M. C.; Roseiro, Luisa B.; Carvalheiro, Florbela; Pereira, Helena; Duarte, Luís C.ABSTRACT: Pinus pinea nuts are commercial relevant Mediterranean edible forest nuts, with an increasing production and market value, whose industrial processing yields a lignocellulosic by-product, the pine nut shells, currently only used for combustion. Little research has been done on pine nut shells that could support a value-added application for this residue. This work studies for the first time the production of oligosaccharides by autohydrosis, and aims at an integrated upgrade within the biorefinery framework. Autohydrolysis was explored in the temperature range between 150 and 230 degrees C (corresponding to severity factors 2.13-4.63). Oligosaccharides, mainly xylo-oligosaccharides (95% of the total), were the key soluble products, reaching 28.7 g/100 g of xylan of the feedstock at the optimal conditions (log R-0 4.01). Other products were monosaccharides and phenolic compounds that reached 7.8 and 4.7 g/L, respectively, under the most severe conditions. The stability of the oligosaccharides at different temperatures (room, 37 degrees C and 100 degrees C) and pH (between 1 and 11) grant them significant market potential in the food and pharma sectors. The pre-treated pine nut shells by autohydrolysis presented an improved, although low, enzymatic digestibility (14%), and an improved high-heating value, therefore advising their further valorization by thermochemical pathways.
- Detoxification of hemicellulosic hydrolysates from extracted olive pomace by diananofiltrationPublication . Brás, Teresa; Guerra, Vera; Torrado, Ivone; Lourenço, Pedro; Carvalheiro, Florbela; Duarte, Luís C.; Neves, Luísa A.Xylitol can be obtained from the pentose-rich hemicellulosic fraction of agricultural residues, such as extracted olive pomace, by fermentation. Dilute acid hydrolysis of lignocellulosic materials, produces the release of potential inhibitory compounds mainly furan derivatives, aliphatic acids, and phenolic compounds. In order to study the potential on the increase of the hydrolysate fermentability, detoxification experiments based on diananofiltration membrane separation processes were made. Two membranes, NF270 and NF90, were firstly evaluated using hydrolysate model solutions under total recirculation mode, to identify the best membrane for the detoxification. NF270 was chosen to be used in the diananofiltration experiment as it showed the lowest rejection for toxic compounds and highest permeate flux. Diananofiltration experiments, for hydrolysate model solutions and hydrolysate liquor, showed that nanofiltration is able to deplete inhibitory compounds and to obtain solutions with higher xylose content. Conversely to non-detoxified hydrolysates, nanofiltration detoxified hydrolysates enabled yeast growth and xylitol production by the yeast Debaryomyces hansenii, clearly pointing out that detoxification is an absolute requirement for extracted olive pomace dilute acid hydrolysate bioconversion.
- Contribution to "Deliverable 4: Activity 6: Pilot Demonstrations: Pilot testing, 2nd milling campaign"Publication . Ribeiro, Belina; Torrado, Ivone; Penedo, Céu; Eusebio, Ana
- Produção de xilitol: uma via alternativa de valorização do bagaço de azeitona extratadoPublication . Duarte, Luís C.; Carvalheiro, Florbela; Torrado, Ivone; Guerra, Vera; Morais, Ana Rita C.; Ferreira, Cátia; Roseiro, Luisa B.; C. Fernandes, M.; Neves, Luísa A.; Brás, Teresa; Lourenço, Pedro; Lukasik, Rafal M.; Pinto, Filomena
- Microwave-assisted hydrothermal processing of pine nut shells for oligosaccharide productionPublication . Torrado, Ivone; Neves, Beatriz Guapo; Fernandes, M. C.; Carvalheiro, Florbela; Pereira, Helena; Duarte, Luís C.ABSTRACT: Pine nut shells, a biomass residue from the Mediterranean Pinus pinea pine nut industrial processing, were treated by microwave-assisted autohydrolysis to produce xylo-oligosaccharides. Microwave-assisted processes provide alternative heating that may reduce energy input and increase overall process efficiency. The autohydrolysis treatments were performed under isothermal and non-isothermal operations within a wide range of operational conditions (temperature/reaction times) covering several severity regimes (as measured by the log R-0 severity factor). The composition of the autohydrolysis liquors was determined in terms of oligo- and monosaccharides, aliphatic acids and degradation compounds. The process was highly selective towards hemicelluloses hydrolysis and liquid streams containing a mixture of oligomeric compounds (mainly xylo-oligosaccharides) could be obtained under relatively mild operation conditions (190 degrees C, 30 min) with a maximal oligosaccharides' concentration of 18.48 g/L. The average polymerization degree of the obtained oligosaccharides was characterised by HPLC, showing that for the optimal conditions a mixture of oligomers with DPs from 2 to 6.
- Influence of Inhibitors Generated in Lignocellulosic Hydrolysates from Group of Acids on the Growth of Strains TG1 and Tuner of Escherichia coliPublication . Gaspar, Suelen S.; Alves Ferreira Caturra, Júnia Aparecida; Moniz, Patricia; Silva-Fernandes, Talita; Silvestre, Adriana I. R; Torrado, Ivone; Pesce, Gaetano R.; Carvalheiro, Florbela; Duarte, Luís; Fernandes, Maria da ConceiçãoABSTRACT: Concerns over fossil fuels are of increasing interest in biorefineries that utilize lignocellulosic residues. Besides sugars, inhibitors are formed during biomass pretreatment, including acetic acid (AI) and formic acid (FI), which can hinder microbial fermentation. The TG1 and Tuner strains of Escherichia coli were subjected to various acid concentrations. Samples were taken during fermentation to monitor growth, sugar consumption, biomass yield, and product yield. With increasing AI, the TG1 strain maintained stable growth (0.102 1/h), while xylose consumption decreased, and product formation improved, making it better suited for high-acetic-acid industrial applications. In contrast, the Tuner strain performed better under low-inhibitor conditions but suffered metabolic inhibition at high AI levels, compensating by increasing lactic acid production-an adaptation absent in TG1. However, Tuner showed greater resistance to formic acid stress, sustaining higher growth and ethanol production, whereas TG1 experienced a greater metabolic decline but maintained stable acetic acid output. Both strains experienced inhibition in formic acid metabolism, but TG1 had a higher yield despite its lower overall robustness in formic acid conditions. The use of TG1 for value-added compounds such as ethanol or formic acid may help to avoid the use of chemicals that eliminate acetic acid. Tuner could be used for lactic acid production, especially in hydrolysates with under moderate concentration.
- Xylitol Production by Debaryomyces hansenii in Extracted Olive Pomace Dilute-Acid HydrolysatePublication . Morais, Ana Rita C.; Duarte, Luís C.; Lourenço, Pedro; Torrado, Ivone; Brás, Teresa; Neves, Luísa, A.; Carvalheiro, FlorbelaABSTRACT: The extracted olive pomace (EOP) is an industrial lignocellulosic by-product of olive pomace oil extraction, currently mainly used for energy production through combustion. In this work, the hemicellulosic fraction of EOP was selectively hydrolyzed by diluted acid hydrolysis to obtain pentose-rich hydrolysates that can potentially be upgraded by Debaryomyces hansenii, targeting xylitol production. The monosaccharides and degradation by-products released along the pre-treatment were quantified and several detoxification methods for the removal of potentially toxic compounds were evaluated, including pH adjustment to 5.5, the use of anion-exchange resins, adsorption into activated charcoal, concentration by evaporation, and membrane techniques, i.e., nanofiltration. The latter approach was shown to be the best method allowing the full removal of furfural, 41% of 5-hydroxymethylfurfural, 54% of acetic acid, and 67% of the phenolic compounds present in the hydrolysate. The effects of the supplementation of both non-detoxified and detoxified hydrolysates were also assessed. The non-detoxified hydrolysate, under aerobic conditions, supported the yeast growth and xylitol production at low levels. Supplementation with the low-cost corn steep liquor of the nanofiltration detoxified hydrolysate showed a higher xylitol yield (0.57 g/g) compared to the non-detoxified hydrolysate. The highest xylitol productivity was found in hydrolysate detoxified with anionic resins (0.30 g/L-h), which was 80% higher than in the non-detoxified culture medium. Overall, the results showed that EOP dilute acid hydrolysates can efficiently be used for xylitol production by D. hansenii if detoxification, and supplementation, even with low-cost supplements, are performed.