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- Métodos de fraccionamento de biomassa para as biorrefinariasPublication . Carvalheiro, Florbela; Duarte, Luís C.; Lukasik, Rafal M.; Moniz, PatriciaO desenvolvimento de processos que permitam o fraccionamento eficiente da biomassa (tradicionalmente designados por pré-tratamentos) constitui uma parte muito significativa do esforço científico que tem sido feito para a transformação das biorrefinarias numa realidade industrial. Este artigo apresenta uma breve revisão dos processos de fraccionamento, sendo dada particular atenção a processos emergentes, discutindo também as suas possíveis vantagens e limitações.
- The role of heterotrophic microalgae in waste conversion to biofuels and bioproductsPublication . Silva, Teresa Lopes da; Moniz, Patricia; Silva, Carla; Reis, AlbertoABSTRACT: In the last few decades, microalgae have attracted attention from the scientific community worldwide, being considered a promising feedstock for renewable energy production, as well as for a wide range of high value-added products such as pigments and poly-unsaturated fatty acids for pharmaceutical, nutraceutical, food, and cosmetic markets. Despite the investments in microalgae biotechnology to date, the major obstacle to its wide commercialization is the high cost of microalgal biomass production and expensive product extraction steps. One way to reduce the microalgae production costs is the use of low-cost feedstock for microalgae production. Some wastes contain organic and inorganic components that may serve as nutrients for algal growth, decreasing the culture media cost and, thus, the overall process costs. Most of the research studies on microalgae waste treatment use autotrophic and mixotrophic microalgae growth. Research on heterotrophic microalgae to treat wastes is still scarce, although this cultivation mode shows several benefits over the others, such as higher organic carbon load tolerance, intracellular products production, and stability in production all year round, regardless of the location and climate. In this review article, the use of heterotrophic microalgae to simultaneously treat wastes and produce high value-added bioproducts and biofuels will be discussed, critically analyzing the most recent research done in this area so far and envisioning the use of this approach to a commercial scale in the near future.
- Green Fractionation Approaches for the Integrated Upgrade of Corn CobsPublication . Fialho, João; Moniz, Patricia; Duarte, Luís C.; Carvalheiro, FlorbelaABSTRACT: Corn cob is an abundant agricultural residue worldwide, with high potential and interesting composition, and its valorization still needs to be studied. Selectively fractionating its structural components (hemicellulose, cellulose, and lignin), value-added products can be produced, eliminating waste. In this work, integrated fractionation approaches were developed and evaluated. First, an organosolv process was optimized (ethanol:water, 50:50, w/w). Then, as a comparative method, alkaline delignification (using NaOH, 1-2%) was also studied. The organosolv process allowed a significant delignification of the material (79% delignification yield) and, at the same time, a liquid phase containing a relevant concentration (14.6 g/L) of xylooligosaccharides (XOS). The resulting solid fraction, rich in cellulose, showed an enzymatic digestibility of 90%. The alkaline process increased the delignification yield to 94%, producing a solid fraction with a cellulose enzymatic digestibility of 83%. The two later techniques were also used in a combined strategy of hydrothermal processing (autohydrolysis) followed by delignification. The first allowed the selective hydrolysis of hemicellulose to produce XOS-rich hydrolysates (26.8 g/L, 67.3 g/100 g initial xylan). The further delignification processes, alkaline or organosolv, led to global delignification yields of 76% and 93%, respectively. The solid residue, enriched in glucan (above 75% for both combined processes), also presented high enzymatic saccharification yields, 89% and 90%, respectively. The fractionation strategies proposed, and the results obtained are very promising, enabling the integrated upgrading of this material into a biorefinery framework.
- Evaluating low-cost substrates for Crypthecodinium cohnii lipids and DHA production, by flow cytometryPublication . Taborda, Tiago; Moniz, Patricia; Reis, Alberto; Silva, Teresa Lopes daABSTRACT: Crypthecodinium cohnii growth was studied on pure carbon sources (glucose, acetate, glycerol) and low-cost complex carbon sources (sugarcane molasses, crude glycerol and vinegar effluent) for lipid and DHA production. Among the pure substrates, glucose induced the highest lipid content (14.75% w/w DCW) and DHA content (7.14 mg g(-1) DCW). Among the low-cost substrates, the highest lipid and DHA content were observed for the crude glycerol assay (14.7% w/w DCW and 6.56 mg g(-1), respectively). Molasses induced the highest proportion of DHA of total fatty acids (49.58% w/w TFA) among all the substrates studied. Flow cytometric analysis revealed that the vinegar effluent induced the highest proportion of C. cohnii cells with injured membrane (92.8%). These results foresee the possibility of using these low-cost substrates at a larger scale for C. cohnii DHA and biodiesel production, aiming at zero wastes and process costs reduction.
- Hydrothermal processing of corn residues:process optimisation and products characterisationPublication . Moniz, Patricia; Gírio, Francisco; Carvalheiro, Florbela; Pereira, HelenaHydrothermal processing was used as pre-treatment method for the selective solubilisation of hemicellulose from corn residues (leaves and stalks). The raw material was treated at a liquidto- solid ratio of 10 g/g, under non-isothermal conditions (150-240ºC) and the effect of treatment on the composition of both liquid and solid phases was evaluated. The yields of solid residue and soluble products, e.g., oligosaccharides, monosaccharides, acetic acid and degradation compounds, such as furfural, hydroxymethylfurfural are presented and interpreted using the severity factor (log R0). The operational conditions leading to the maximum recovery of XOS (53% of initial (arabino)xylan) and for highest glucan content of the solid residue (64%) were established for log R0 of 3.75 and 4.21, respectively. Under the severest condition 95% of xylan was selectively solubilised and 90% of initial glucan was recovered on the solid residue, making it very attractive for further processing in a biorefinery framework.
- Fractionation of hemicelluloses and lignin from rice straw by combining autohydrolysis and optimised mild organosolv delignificationPublication . Moniz, Patricia; Lino, João; Duarte, Luís C.; Roseiro, Luisa B.; Boeriu, Carmen G.; Pereira, Helena; Carvalheiro, FlorbelaAn integrated strategy was followed to valorise rice straw, one of the most relevant biomass feedstocks available worldwide, to selectively recover solubilised hemicelluloses and lignin. The pathway encompassed the use of autohydrolysis to hydrolyse the hemicelluloses and an ethanol-based organosolv process to solubilise lignin. Several autohydrolysis conditions were assayed with the best results obtained at 210 ºC (log R0 4.15), which enabled high removal of hemicelluloses, yielding an oligosaccharide-rich hydrolysate and a treated biomass with low content of hemicelluloses and enriched in cellulose and lignin. The effects of ethanol concentration (5 to 75%), and reaction time (0 to 24 h) on lignin removal under mild temperature (30 ºC) were studied. In optimal conditions (60.5% ethanol, 24h) the delignification yield reached 42%, where as glucan solubilisation was below 17%. Lignin solubilisation yield was not influenced by the organosolv treatment duration while ethanol concentration favored the delignification up to 60.5% ethanol. The organosolv liquors contained economic interesting ligninderived compounds such as vanillin, ferulic, and coumaric acids. The chemical composition and enzymatic digestibility of the treated biomass from autohydrolysis and organosolv delignification were compared, with the latter presenting an almost 10% higher enzymatic digestibility than the former.
- Hydrothermal production and gel filtration purification of xylo-oligosaccharides from rice strawPublication . Moniz, Patricia; Pereira, Helena; Duarte, Luís C.; Carvalheiro, FlorbelaHydrothermal treatment (autohydrolysis) is an advantageous alternative to fractionate biomass that was not yet explored for rice straw. In this work, the process was optimised and proved to be highly selective towards hemicellulose. Hydrolysates containing a mixture of oligomeric compounds (mainly xylo-oligosaccharides, XOS), could be obtained under relatively mild operation conditions (210 degrees C, logR(0) = 3.59), yielding a maximum of 40.1 g/100 g of initial xylan. The produced XOS were separated by molecular mass using gel filtration chromatography (GFC). Different fractions of purified XOS were obtained ranging from small polysaccharides and high DP oligosaccharides (DP >= 23), to medium and low DP oligosaccharides (DP >= 3), and separated fractions of by-products (acetic acid, furan derivatives and phenols) as well as di-, and monosaccharides. GFC was an efficient purification method enabling the recovery of interesting categories of XOS that can have potential applications to the pharma, food and feed industries.
- Fermentation Wastes from Chrypthecodinium cohnii Lipid Production for Energy Recovery by Anaerobic DigestionPublication . Eusebio, Ana; Moniz, Patricia; Silva, Teresa Lopes da; Marques, Isabel PaulaABSTRACT: Wastes generated during the cultivation of marine microalga Crypthecodinium cohnii and after the lipid extraction process, were energetically valorized into biogas production through anaerobic digestion (AD). The tested wastes were extracted microalgae (Ae) with hexane (AeH) using supercritical extraction methods (AeS) and the supernatant obtained after culture medium centrifugation (M). The digestion of the algae biomass in the admixture with the supernatant medium (AeH+M+I and AeS+M+I) provided a higher methane content and a higher methane yield (582 and 440 L CH4/kg VS) than the substrates Ae and M, individually digested (155 and 96 L CH4/kg VS, respectively). Flow cytometry monitoring processes during AD indicated that the yield of the accumulated biogas was influenced by the operating conditions. The mixture of AeH+M+I was the only assay with a proportion of cells with less damaged membranes after AD, providing the highest methane yield and productivity (582 L CH4/kg VS and 31 L CH4/kg VS.d, respectively) and the highest energetic potential of 5.8 KWh/kg VS of all the substrates. From the results, AD integration to lipid production by C. cohnii to recover energy from the generated wastes enhanced the sustainability of the entire process and promoted the practice of zero waste.
- A face escura da biotecnologia de microalgas : a biorefinaria de microalgas heterotróficas direcionada para a produção de lípidos ricos em compostos Ω-3 e biocombustíveisPublication . Silva, Teresa Lopes da; Moniz, Patricia; Reis, AlbertoRESUMO: As microalgas podem crescer em substratos de baixo custo, como subprodutos ou efluentes industriais, conseguindo remover poluentes e, simultaneamente, produzir biocompostos com interesse comercial, contribuindo, desta forma, para o desenvolvimento da bioeconomia mundial. As microalgas autotróficas utilizam o dióxido de carbono como fonte de carbono, e necessitam de luz para se desenvolverem. As microalgas heterotróficas não necessitam de luz e utilizam carbono orgânico para se desenvolverem. A não sazonalidade, a não dependência de luz e das condições climáticas são alguns dos pontos fortes da tecnologia de cultivo das microalgas heterotróficas, particularmente adequada para países localizados em latitudes elevadas, como os países da União Europeia. Algumas destas microalgas produzem altos teores de lípidos que podem ser extraídos e fraccionados em compostos ω-3 (utilizados nas indústrias farmacêutica e alimentar) e em biodiesel, num conceito de biorefinaria da biomassa algal. Esta comunicação apresenta as diferentes estratégias que recentemente têm sido utilizadas para cultivar microalgas heterotróficas para produção de lípidos, enfatizando a importância de um sistema integrado que valorize todas as frações lipídicas da biomassa algal para diversas aplicações, tendo em vista um processo sustentável assente nos conceitos da bioeconomia circular.
- Pulp properties resulting from different pretreatments of wheat straw and their influence on enzymatic hydrolysis ratePublication . Rosseberg, Christine; Steffien, Doreen; Bremer, Martina; Koening, Swetlana; Carvalheiro, Florbela; Duarte, Luís C.; Moniz, Patricia; Hoernicke, Max; Bertau, Martin; Fischer, SteffenWheat straw was subjected to three different processes prior to saccharification, namely alkaline pulping, natural pulping and autohydrolysis, in order to study their effect on the rate of enzymatic hydrolysis. Parameters like medium concentration, temperature and time have been varied in order to optimize each method. Milling the raw material to a length of 4 mm beforehand showed the best cost–value-ratio compared to other grinding methods studied. Before saccharification the pulp can be stored in dried form, leading to a high yield of glucose. Furthermore the relation of pulp properties (i.e. intrinsic viscosity, KLASON-lignin and hemicelluloses content, crystallinity, morphology) to cellulose hydrolysis is discussed.