UB - Artigos em revistas internacionais
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- Alternative feedstocks for high-quality biodiesel: Lipid production from eucalyptus bark hydrolysate by Yarrowia lipolytica W29 using different cultivation modesPublication . Dias, Bruna; Lopes, Marlene; Marques, Susana; Gírio, Francisco; Belo, IsabelABSTRACT: Microbial lipids produced by yeasts from lignocellulosic biomass are a promising feedstock for the biodiesel industry, providing a renewable energy source as an alternative to traditional fossil fuels. This study investigated the potential of Yarrowia lipolytica W29 to produce lipid-rich biomass from undetoxified sugar-concentrated eucalyptus bark hydrolysate (EBH). The lipid concentrations achieved in batch cultures (13.4 g L-1) were the highest for wild-type Y. lipolytica strains in lignocellulosic hydrolysates. Different two-stage cultivation modes (repeated batch, continuous-feeding fed-batch, and pulse fed-batch) were studied to enhance biomass and lipid production. The cell and lipid mass was higher in pulse fed-batch and continuous-feeding fed-batch cultures than batch cultures. Production of citric acid, a side product of industrial interest, was improved in the continuous-feeding fed-batch culture. Microbial lipids produced by Y. lipolytica W29 were highly unsaturated and mainly composed of oleic acid (50% to 53%). The estimated properties of the biodiesel that would be obtained from these intracellular lipids would meet the international biodiesel standards EN 14214 and ASTM D6751. This study demonstrates the feasibility of using EBH for Y. lipolytica lipid production and promotes the sustainable production of high-quality biodiesel from lignocellulosic feedstocks.
- Bridging gaps in biorefineries: The unexplored role of social dimension in life cycle assessment researchPublication . Ortigueira, Joana; Lopes, TiagoABSTRACT: This review examines the disregarded role of social dimensions in Life Cycle Assessment (LCA) within biorefinery implementation, addressing the question: "How can the inclusion of social factors in LCA improve sustainability assessments, and what are the implications of the limited Social Life Cycle Assessment (S-LCA) studies in biorefineries?" A systematic literature review was conducted using Web of ScienceTM, focusing on studies that integrate social dimensions in LCA. Bibliometric analysis using the bibliometrix R-package and VOSviewer identified key trends, influential papers, and research gaps. Results revealed a significant gap in incorporating social dimensions into biorefinery LCA, with most studies focusing primarily on environmental and economic impacts. Limited attention is given to social aspects such as community well-being, labor rights, and social equity. Case studies that included social factors demonstrated a more comprehensive sustainability assessment, emphasizing the importance of stakeholder engagement and social acceptability in biorefinery projects. This review highlights the need for standardized social indicators and methodologies to integrate social dimensions effectively. The lack of S-LCA in biorefinery implementation reflects a critical gap in sustainability assessments. Addressing this requires developing a unified S-LCA methodology, fostering interdisciplinary collaboration, and encouraging stakeholder participation to ensure diverse perspectives are considered. Ultimately, incorporating social dimensions is essential for achieving a more balanced and comprehensive evaluation of biorefinery sustainability.
- Design optimisation of five pilot-scale two-stage vertical flow-constructed wetlands for piggery wastewater treatmentPublication . Karan, N.; Gogoi, Jayanta; Ganguly, Anasuya; Brito, António; Marques dos Santos, C.; de Oliveira Corrêa, Diego; Gouveia, Luisa; Mutnuri, SrikanthABSTRACT: With growing pig farming, sustainable piggery wastewater treatment methods are essential for environmental protection. This study evaluated five pilot-scale two-stage vertical flow-constructed wetlands (VFCWs) with varying configurations of aeration, plantation, and saturation zones. Three VFCW configurations (1VFCW, 2VFCW, and 3VFCW) were unsaturated, while 4VFCW and 5VFCW were saturated in the second stage (up to 60 and 90 cm, respectively). The 5VFCW featured a stacked configuration with no space between its two stages. Passive aeration was selectively applied in 2VFCW, 3VFCW, 4VFCW, and 5VFCW, while plants were present in most configurations except the control. Saturated 4VFCW achieved the highest removal efficiency for TN (77.03 ± 16.24%) and NO3− (46.06 ± 45.96%), while the stacked 5VFCW showed the highest removal for chemical oxygen demand (COD) (94.17 ± 4.85%) and Total ammoniacal nitrogen (TOC) (86.35 ± 6.78%). Unsaturated 1VFCW excelled in TAN removal (98.89 ± 0.33%), and the control system (C) showed the highest removal efficiency for PO43− (90.38 ± 6.52%) and TOC (87.52 ± 9.83%). Overall, 4VFCW emerged as the most balanced and effective system, supported by an optimal combination of aerobic and anaerobic conditions that facilitated sequential nitrification and denitrification, along with an extended hydraulic retention time due to saturation.
- Energy potential of elephant grass broth as biomass for biogas productionPublication . da Silva, Guilherme Henrique; Renato, Natalia dos Santos; Coelho, Felipe Ferreira; Donato, Thiago Paiva; Otenio, Marcelo; Machado, Juarez; Delgado dos Reis, Alberto JoséABSTRACT: The growing demand for clean energy has highlighted plant biomass as a valuable alternative, supporting sustainable development goals. Elephant grass (EG) is a promising feedstock due to its adaptability to diverse soils and climates, high dry matter production, and substantial energy yield. This study aimed to evaluate and characterize six selected EG genotypes (BRS Capia & ccedil;u, T_23.1, T_23.2, T_41.2, T_47.1, and T_51.5) based on their broth productivity and energy yield. Analysis of the broth's yield and physicochemical properties revealed that the by-product extracted from the biomass had a high residual energy value. Additionally, extracting the broth reduces the grass's biomass moisture content, enhancing its calorific value and improving the bagasse quality for combustion in boilers, thus optimizing energy production. This study demonstrates that the promising EG genotypes T_47.1, T_41.2, and T_23.1 presented relevant energy values ranging from 4248.12 to 4304.06 kcal kg- 1 of bagasse and thus are suitable for energy production through direct combustion. The extracted broth is a valuable residual energy source that can be utilized industrially after anaerobic digestion. Future research should focus on the environmental and economic effectiveness of EG broth as an energy source from waste and its potential for biogas production.
- Production of sustainable aviation fuel precursors using the oleaginous yeast Rhodotorula toruloides PYCC 5615 cultivated on eucalyptus bark hydrolysatePublication . Saraiva Lopes da Silva, Maria Teresa; Dutra, Francisca; Gomes, Miguel; Costa, Paula; Paradela, Filipe; Ferreira, Frederico Castelo; Torres Faria, Nuno Ricardo; Mugica, Paula; Pinheiro, Helena M.; Sá-Correia, Isabel; Gírio, Francisco; Marques, SusanaABSTRACT: Sustainable aviation fuels (SAF) obtained from renewable sources of carbon can reduce carbon dioxide emissions and contribute for mitigating climate changes. In the present study, the yeast Rhodotorula toruloides PYCC 5615 was found to be highly promising for the bioconversion of eucalyptus bark hydrolysate and the accumulation of intracellular lipids which were further thermochemically processed to bioenergy intermediaries for SAF production. Two growth medium formulations were tested. Eucalyptus bark hydrolysate, obtained by steam explosion followed by enzymatic hydrolysis, was supplemented with yeast nitrogen base medium or with corn steep liquor and mineral medium. The latter produced the highest fatty acid content and productivity (30 % w/w and 0.11 g/ (L.h) respectively). Thereafter, the whole yeast biomass (WB) and the de-oiled biomass (DOB), obtained after lipid extraction, were processed into Bio-crude using a hydrothermal liquefaction (HTL) reactor, with a yield of approximate to 40 % (w/w). The two obtained Bio-crude fractions and the yeast lipids fraction (YL) were further upgraded by hydrodeoxygenation (HDO), to remove oxygen atoms and increase the hydrocarbon content, resulting in a Bio-crude composed of linear long-chain fatty acids suitable for processing to SAF. The best Bio-crude characteristics was observed for WB and YL fractions, with 34.8 % and 40.7 % of hydrocarbons, respectively. Both WB and YL hydrocarbons were composed of C15-C17 compounds. These results demonstrate the potential of an integrated process based on microbial oils from R. toruloides PYCC 5615 to produce SAF precursors from Eucalyptus bark residues, contributing for the sustainable jetfuel bioproduction process.
- 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.
- Recovery of Nd3+ and Dy3+ from E-Waste Using Adsorbents from Spent Tyre Rubbers: Batch and Column Dynamic AssaysPublication . Nogueira, Miguel; Matos, Inês; Bernardo, Maria; Pinto, Filomena; Fonseca, Isabel Maria; Lapa, NunoABSTRACT: This paper investigates the use of spent tyre rubber as a precursor for synthesising adsorbents to recover rare earth elements. Through pyrolysis and CO2 activation, tyre rubber is converted into porous carbonaceous materials with surface properties suited for rare earth element adsorption. The study also examines the efficiency of leaching rare earth elements from NdFeB magnets using optimised acid leaching methods, providing insights into recovery processes. The adsorption capacity of the materials was assessed through batch adsorption assays targeting neodymium (Nd3+) and dysprosium (Dy3+) ions. Results highlight the superior performance of activated carbon derived from tyre rubber following CO2 activation, with the best-performing adsorbent achieving maximum uptake capacities of 24.7 mg.g(-1) for Nd3+ and 34.4 mg.g(-1) for Dy3+. Column studies revealed efficient adsorption of Nd3+ and Dy3+ from synthetic and real magnet leachates with a maximum uptake capacity of 1.36 mg.g(-1) for Nd3+ in real leachates and breakthrough times of 25 min. Bi-component assays showed no adverse effects when both ions were present, supporting their potential for simultaneous recovery. Furthermore, the adsorbents effectively recovered rare earth elements from e-waste magnet leachates, demonstrating practical applicability. This research underscores the potential of tyre rubber-derived adsorbents to enhance sustainability in critical raw material supply chains. By repurposing waste tyre rubber, these materials offer a sustainable solution for rare earth recovery, addressing resource scarcity while aligning with circular economy principles by diverting waste from landfills and creating value-added products.
- New Insights on Gordonia alkanivorans Strain 1B Surface-Active Biomolecules: Gordofactin PropertiesPublication . Tavares, João; Paixão, Susana M.; Silva, Tiago; Alves, LuísABSTRACT: Biosurfactants/bioemulsifiers (BSs/BEs) can be defined as surface-active biomolecules produced by microorganisms with a broad range of applications. In recent years, due to their unique properties like biodegradability, specificity, low toxicity, and relative ease of preparation, these biomolecules have attracted wide interest as an eco-friendly alternative for several industrial sectors, escalating global microbial BS/BE market growth. Recently, Gordonia alkanivorans strain 1B, a bacterium with significant biotechnological potential, well known for its biodesulfurizing properties, carotenoid production, and broad catabolic range, was described as a BS/BE producer. This study focuses on the characterization of the properties of the lipoglycopeptide BSs/BEs produced by strain 1B, henceforth referred to as gordofactin, to better understand its potential and future applications. Strain 1B was cultivated in a chemostat using fructose as a carbon source to stimulate gordofactin production, and different purification methods were tested. The most purified sample, designated as extracted gordofactin, after lyophilization, presented a specific emulsifying activity of 9.5 U/mg and a critical micelle concentration of 13.5 mg/L. FT-IR analysis revealed the presence of basic hydroxyl, carboxyl, ether, amine/amide functional groups, and alkyl aliphatic chains, which is consistent with its lipoglycopeptide nature (60% lipids, 19.6% carbohydrates, and 9% proteins). Gordofactin displayed remarkable stability and retained emulsifying activity across a broad range of temperatures (30 degrees C to 80 degrees C) and pH (pH 3-12). Moreover, a significant tolerance of gordofactin emulsifying activity (EA) to a wide range of NaCl concentrations (1 to 100 g/L) was demonstrated. Although with a great loss of EA in the presence of NaCl concentrations above 2.5%, gordofactin could still tolerate up to 100 g/L NaCl, maintaining about 16% of its initial EA for up to 7 days. Furthermore, gordofactin exhibited growth inhibition against both Gram-positive and Gram-negative bacteria, and it demonstrated concentration-dependent free radical scavenging activity for 2,2-diphenyl-1-picrylhydrazyl (IC50 approximate to 1471 mg/L). These promising features emphasize the robustness and potential of gordofactin as an eco-friendly BS/BE alternative to conventional surfactants/emulsifiers for different industrial applications.
- Biopolymers Derived from Forest Biomass for the Sustainable Textile IndustryPublication . Dias, J. C.; Marques, Susana; Branco, Pedro C.; Rodrigues, Thomas; Torres, Cristiana A.V.; Freitas, Filomena; Evtuguin, Dmitry; Silva, CarlaABSTRACT: In line with environmental awareness movements and social concerns, the textile industry is prioritizing sustainability in its strategic planning, product decisions, and brand initiatives. The use of non-biodegradable materials, obtained from non-renewable sources, contributes heavily to environmental pollution throughout the textile production chain. As sustainable alternatives, considerable efforts are being made to incorporate biodegradable biopolymers derived from residual biomass, with reasonable production costs, to replace or reduce the use of synthetic petrochemical-based polymers. However, the commercial deployment of these biopolymers is dependent on high biomass availability and a cost-effective supply. Residual forest biomass, with lignocellulosic composition and seasonably available at low cost, constitutes an attractive renewable resource that might be used as raw material. Thus, this review aims at carrying out a comprehensive analysis of the existing literature on the use of residual forest biomass as a source of new biomaterials for the textile industry, identifying current gaps or problems. Three specific biopolymers are considered: lignin that is recovered from forest biomass, and the bacterial biopolymers poly(hydroxyalkanoates) (PHAs) and bacterial cellulose (BC), which can be produced from sugar-rich hydrolysates derived from the polysaccharide fractions of forest biomass. Lignin, PHA, and BC can find use in textile applications, for example, to develop fibers or technical textiles, thus replacing the currently used synthetic materials. This approach will considerably contribute to improving the sustainability of the textile industry by reducing the amount of non-biodegradable materials upon disposal of textiles, reducing their environmental impact. Moreover, the integration of residual forest biomass as renewable raw material to produce advanced biomaterials for the textile industry is consistent with the principles of the circular economy and the bioeconomy and offers potential for the development of innovative materials for this industry.
- Optimizing bacterial nanocellulose production from eucalyptus bark: A circular approach to wastewater management and resource recoveryPublication . Rodrigues, Ana Cristina; Martins, Daniela; Duarte, Maria Salomé; Marques, Susana; Gama, Miguel; Dourado, Fernando; Carvalho, Ricardo; Cavaleiro, AnaABSTRACT: The production cost of bacterial nanocellulose (BNC) is a major limitation to its widespread use. However, this limitation can be addressed by using alternative low-cost substrates and high-yield strains. Agro-industrial wastederived substrates offer a cost-effective and sustainable solution, but their high organic load often requires additional downstream wastewater treatments. Here, we optimized static BNC production using eucalyptus bark hydrolysate (EBH) as a low-cost carbon source and proposed a circular approach for wastewater management. Optimization was performed using response surface methodology - central composite design. The optimized EBH medium yielded a 39.7-fold increase compared to standard medium, with a maximum BNC production of 8.29 f 0.21 g/L. Fermentation wastewater only (WaF) and combined with BNC washing streams (WaW) revealed high levels of organic matter, namely chemical oxygen demand (COD) of 159.0 f 2.0 and 41.1 f 0.3 g/L, and volatile solids (VS) of 99.5 f 0.9 and 26.3 f 0.2 g/L, respectively, requiring treatment before disposal. A sequential anaerobic-aerobic digestion was investigated for wastewater treatment and valorisation. Anaerobic digestion proved to be effective in treating the wastewater: methanization percentages over 87 % were achieved, and methane productions of 486 f 2 and 544 f 30 L/kg VS were obtained from WaF and WaW, respectively. Subsequent aerobic treatment was unsuccessful in further reducing COD levels (approximately 1.5 g/L). Notably, treated wastewater was recycled into the production process up to 45 % without affecting the BNC yield. This study provides valuable insights into the optimization of BNC production from lignocellulosic biomass and the management of wastewater streams, contributing to the development of a more sustainable and economically viable process.