UB - Artigos em revistas internacionais
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- Advancing Sustainable Production of High-Performance Cellulose PulpsPublication . Moran, Guadalupe; Costa Trigo, Iván; Bastida, Gabriela Adriana; Mazega, André; Duran, Josep; Domínguez, José Manuel; Vilaseca, FabiolaABSTRACT: Highlights What are the main findings? Enzymatic hydrolysis pretreatment of industrial pulps Pulp composition influencing the enzymatic performance Enhanced conditions for high-performance cellulose pulps What is the implication of the main finding? Sustainable methodology to produce cellulose pulps Lower environmental impact and alignment with circular economic principles Improvements in tensile strength, air permeability, hydrophobicity, and internal bondingHighlights What are the main findings? Enzymatic hydrolysis pretreatment of industrial pulps Pulp composition influencing the enzymatic performance Enhanced conditions for high-performance cellulose pulps What is the implication of the main finding? Sustainable methodology to produce cellulose pulps Lower environmental impact and alignment with circular economic principles Improvements in tensile strength, air permeability, hydrophobicity, and internal bondingAbstract With a growing demand for renewable resources in high-performance materials, sustainable methods are preferred for their lower environmental impact and alignment with circular economy principles. Among these, enzymatic hydrolysis remains relatively underexplored yet shows strong potential for cellulose fibrillation, offering a promising route that may lower energy requirements by minimizing the need for extensive refining compared to conventional mechanical or chemical approaches. In this study, enzyme cocktails rich in cellulase and xylanase were applied to three industrial pulps, sulphite, bleached Kraft eucalyptus and thermomechanical pine, to produce high-performance cellulose pulps. Treatments were carried out using varying enzyme loads (5-40 filter paper units per gram of dry pulp, FPU/gdp) and reaction times (1-16 h). The resulting chemical composition, structural morphology, and physical-mechanical properties were systematically evaluated. The findings revealed that pulp composition strongly influenced enzymatic treatment, affecting surface fibrillation, fibre aggregation, swelling, and fibre shortening. Under optimized conditions, enzymatic pretreatment significantly enhanced paper performance, with improvements in tensile strength, air permeability, hydrophobicity, and internal bonding. Overall, enzymatic hydrolysis represents a sustainable solution and a strategy which could reduce energy expenditures to high-performance cellulose pulps, suitable as reinforcing fibres in packaging applications.
- Improving Carbon Fixation and Acetate Production from Syngas Fermentation: On-Demand Versus Continuous FeedingPublication . Pacheco, Marta; Silva, Tiago; silva, carla; Moura, PatríciaABSTRACT: Syngas fermentation is a promising carbon capture and utilization (CCU) technology for producing carboxylic acids while transforming low-cost waste gas into high-value products. This study evaluates the two bioreactor feeding strategies for synthesis gas (syngas) fermentation by Eubacterium callanderi (formerly Butyribacterium methylotrophicum) strain Marburg-on-demand feeding (ODF) and continuous feeding (CF)-with a synthetic syngas mixture of 23 vol% CO2, 29 vol% CO, 32 vol% H2, and 16 vol% CH4, mimicking the syngas from lignocellulosic gasification. The ODF assay achieved a maximum syngas consumption rate of 112 mL/h, yielding 24.1 g/L acids, namely 22.9 g/L acetate and 1.3 g/L butyrate. CF of syngas at 223 mL/h required more gas (62.9 L) to produce 22.7 g/L total acids, from which 19.0 g/L acetate and 3.7 g/L butyrate were achieved. The CF-specific production rate (gproduct/gdry_cell_weight/hour) reached 0.5 g/gDCW/h (acetate) and 0.17 g/gDCW/h (butyrate), outperforming ODF with 0.3 and 0.02 g/gDCW/h, respectively. ODF minimized gas wastage and enabled CH4 accumulation inside the bioreactor up to approximately 78 vol%, while CF led to CO2 accumulation, indicating a need for more efficient CO2 utilization strategies, such as sequential fermentations. This work highlights the critical impact of the two feeding options studied with regard to scaling up the carbon-efficient production of carboxylic acids, and indicates that both strategies can have potential applications. ODF is ideal for increasing carbon fixation and achieving, simultaneously, gas cleaning, while CF fermentations are better suited to maximizing the acid production rate.
- Assessment of piggery wastewater treatment in vertical flow constructed wetlands: role of plants and aerationPublication . de Oliveira Corrêa, Diego; Ferreira, Alice; Ribeiro, Belina; Gogoi, Jayanta; Karan, N.; Nalwad, A.; Ganguly, A.; Mutnuri, S.; Gouveia, LuisaABSTRACT: Piggery wastewater (PWW), rich in pollutants, poses significant environmental risks if not properly treated. Natural treatment processes, such as constructed wetlands (combined action of plants, substrates, and microbes) and microalgae cultivation, offer sustainable and low-cost alternatives for managing these effluents while enabling resource recovery. This study represents an initial step toward optimizing key operational conditions, such as aeration (passive and active), vegetation presence, and the use of single or sequential Vertical Flow Constructed Wetlands (VFCWs), for the treatment of piggery wastewater, using different experimental setups, at a laboratory scale. Indoor experiments were conducted over an 8-week period to optimize operational conditions for the treatment of PWW. The VFCWs, arranged in two stages and operated in series through gravity flow, were fed daily and monitored weekly. The best removal rates of total Kjeldahl nitrogen (42.9 %), ammoniacal nitrogen (50.3 %), and chemical oxygen demand (20.5 %), were observed in the second stage of VFCW without aeration and with plant. Nitrate and phosphorus levels increased during the experiment, likely due to microbial activity within the substrate and plant root zones. The final goal is to treat the piggery wastewater from a rural farm in India, produce electricity (by a Microbial Fuel Cell), to generate an effluent suitable for microalgae cultivation, with the produced biomass intended for use either as a biostimulant to enhance cereal crops included in pig diets or as a direct nutritional supplement in pig feed.
- Extraction and assessment of the colouring capacity of Arthrospira platensis-derived pigmentsPublication . Villaro-Cos, Silvia; Gouveia, Luisa; Vladic, Jelena; Sanchez-Zurano, Ana; Martínez-García, Irene; Lafarga, TomásABSTRACT: This study presents a zero-waste biorefinery approach for the sequential extraction of phycocyanin and chlorophyll from Arthrospira platensis, followed by the valorisation of the remaining biomass as a plant biostimulant. Natural deep eutectic solvents were screened for phycocyanin recovery, with the mixture proline:glycerol:sorbitol:water (1:1:1:13 molar ratio) showing the highest potential (1.15 g⋅100 g-1; p < 0.05). An initial ultrasound-assisted cell wall disruption step significantly enhanced phycocyanin yield by 400–450 % relative to the untreated control (p < 0.05). A response surface methodology optimised extraction achieved a recovery yield of 8.26 g⋅100 g-1 at 39.7 °C and 127.9 min. The phycocyanin-rich extract was used to mimic the blue colour of commercial blue gin, with a minimal colour difference (ΔE) of 4.53. Subsequent chlorophyll extraction from the phycocyanin leftovers yielded an extract that successfully coloured a commercial green alcohol-free apple liquor (ΔE = 3.93) and green gin (ΔE = 1.65). Finally, the residual biomass demonstrated a significant biostimulant capacity, increasing the germination index of various seeds by 80–150 % compared to water (p < 0.05). This work highlights the potential of A. platensis as a sustainable source for natural colourants and agricultural inputs.
- Pretreatment Tunes scCO2 Extract Composition and Bioactivity in Three Microalgae: Chemometric and Molecular Docking InsightsPublication . Vladic, Jelena; Radman, Sanja; Besu, Irina; Stanojkovic, Tatjana; Zloh, Mire; Jerkovic, Igor; Karadžić Banjac, Milica; Ivkovic, Milena; Pereira, Hugo; Gouveia, LuisaABSTRACT: This study explores the impact of enzymatic (ENZ), microwave (MW), and ultrasound (US) pretreatments on supercritical CO2 (scCO2) extraction efficiency, chemical composition, and cytotoxic activity of Tetraselmis sp., Tetradesmus obliquus, and Chlorococcum sp. Pretreatments significantly enhanced extraction yields, with ENZ being most effective for Tetraselmis and Chlorococcum, and MW for T. obliquus. UPLC-HRMS profiling revealed species- and pretreatment-specific shifts: ENZ and US improved pigment recovery in Tetraselmis, while MW enriched carotenoids and chlorophyll derivatives. In Chlorococcum, MW boosted pigment diversity, whereas ENZ and US favored fatty acid derivatives in the extracts. Multivariate analysis confirmed significant compositional changes, particularly after ENZ and MW pretreatments. Tetraselmis extracts, especially those pretreated with MW, exhibited the strongest cytotoxic activity and highest selectivity indices against HeLa and MDA-MB-453 cancer cell lines. Correlation analysis identified compounds such as 2,3-dihydroxypropyl stearate, fucoxanthin, and (3 beta)-3-hydroxystigmast-5-en-7-one as strongly linked to cytotoxicity. Molecular docking further showed that abundant compounds in Tetraselmis extracts have high predicted affinities for cancer-related targets (e.g., BCL2, EGFR, PDK1). The results suggest that cytotoxic effects arise from both specific bioactive compounds and their synergistic interactions. These findings show that pretreatments can purposefully tune scCO2 extracts and provide a data-driven basis for designing more sustainable microalgal extraction workflows.
- Phenological Development, Productivity, and Oil Profiles of Different Safflower Cultivars for Biofuel ProductionPublication . Silva, Raimunda Adlany Dias; Gouveia, Luisa; Rocha, Thomaz Gabriel Barros; Gondim, Amanda Duarte; Lichston, Juliana Espada; Santos, Nataly AlbuquerqueABSTRACT: The production of oilseed biomass to meet the demand of the energy sector is constrained by several factors, including regional soil and climate conditions, phenological and production issues, such as yield and oil profile, and the compatibility of these factors with the requirements of the energy sector. Safflower is a small oilseed, and its brief phenological cycle and high productivity, concentration, and oil profile distinguish it as a notable candidate for research on energy applications. The objective of this study was to analyze the germination, seed vigor, yield, and oil profile parameters of safflower cultivars (IMAmt 1470, IMAmt 894, and IMAmt S525) with a view to determining their potential as biomass for the biofuel production chain, especially biodiesel and renewable aviation hydrocarbons. Safflower cultivars displayed high germination rates and germination vigor after 12 months of storage. They also met the production standards of 6797.7 kg ha-1 in 2021. The cultivar IMAmt-S525 exhibited a high oil content of 35%. The oil compositions of the safflower cultivars included in this study were found to be 9.7% palmitic acid (IMAmt1470), 71.82% linoleic acid (IMAmt 894), and 41% oleic acid (IMAmt 894 harvest 2022). It is recommended that the following cultivars be selected for production: IMAmt 894, IMAmt-S525, and IMAmt 1470, taking into consideration the physiological, production, and oil composition parameters. Since all three cultivars have high standards of physiological quality, productivity, and oil yield, they have the potential to be used as biomass to diversify oilseed matrices for biofuels.
- A solar panel-origin microalga, Coelastrella thermophila D14, with high potential for wastewater biotechnologyPublication . Baldanta, Sara; Ferreira, Alice; Vinuesa, Arantxa Marco; García-García, Isabel; Gouveia, Luisa; Llorens, Juana Maria Navarro; Guevara, GovindaABSTRACT: Extremophilic environments are rich reservoirs for discovering microorganisms with vast biotechnological potential. Among these, microalgae stand out for their pivotal role in sustainable wastewater treatment and nutrient recycling. This study introduces Coelastrella thermophile D14, a microalga isolated from a solar panel, identified through morphological studies and genomic sequencing. The genus Coelastrella has been characterized and classified as highly productive strains valuable for biofuel and bioproduct generation as well as for their ability to produce significant amounts of carotenoids. Experiments revealed the extraordinary resilience of this strain to prolonged desiccation and high-strength piggery wastewater. Notably, D14 cultivated in 10% pig effluent exhibited biostimulant properties, achieving a germination index 23% higher than the control on Lepidium sativum. In a groundbreaking development, we have successfully established an Agrobacterium-mediated transformation protocol for C. thermophila D14, optimizing key parameters for effective T-DNA transfer. This marks a pioneering achievement within the genus Coelastrella. These findings highlight the significant potential of D14 as a robust platform for future biotechnological applications, opening new opportunities for innovative solutions, especially in environmental protection and sustainable agriculture.Key points center dot First microalga from solar panel biofilm: Coelastrella sp. D14 isolated and characterized.center dot Strain D14 tolerates prolonged desiccation and grows well in piggery wastewater.center dot Stable Agrobacterium-mediated transformation enables future metabolic engineering.Key points center dot First microalga from solar panel biofilm: Coelastrella sp. D14 isolated and characterized.center dot Strain D14 tolerates prolonged desiccation and grows well in piggery wastewater.center dot Stable Agrobacterium-mediated transformation enables future metabolic engineering.Key points center dot First microalga from solar panel biofilm: Coelastrella sp. D14 isolated and characterized.center dot Strain D14 tolerates prolonged desiccation and grows well in piggery wastewater.center dot Stable Agrobacterium-mediated transformation enables future metabolic engineering.
- Shining a light on outdoor algal systems for wastewater treatment: How artificial light enhancement impacts biomass costs and life cyclePublication . Magalhães, Iara; Jesus Junior, Maurino Magno; França, Bruna Thomazinho; Silva, Thiago; Saleme Aona de Paula Pereira, Alexia; Souza, Lucas Cescon de Almeida; Rodrigues, Fábio de Ávila; Reis, Alberto; Peixoto Assemany, Paula; Calijuri, Maria LuciaABSTRACT: Microalgae-based wastewater treatment is increasingly viewed as a cleaner production strategy, combining nutrient removal and biomass generation for high-value applications. However, productivity constraints remain a critical barrier to broader implementation. This study examines the viability of integrating light-emitting diodes (LEDs) into outdoor bubble column reactors for domestic wastewater treatment and biomass production, focusing on environmental impacts and techno-economic performance. Three lighting regimes—natural light only (control), 12-h LED cycles, and 24-h LED cycles—were experimentally evaluated and scaled up using Aspen Plus® simulation. Life cycle assessments (LCA) were conducted to quantify environmental impacts (ReCiPe, 2016 method), and a detailed techno-economic analysis determined minimum biomass selling prices. Compared to the control, LED-assisted systems increased biomass yields by 24–34 %, yet capital and operational costs offset productivity gains. Under grid electricity, minimum selling prices considering capital and operational costs ranged from 80.76 to 91.37 USD/kg for LED systems versus 68.85 USD/kg for the control. Photovoltaic (PV) integration reduced operational costs by up to 16.89 %, but LED scenarios remained more expensive. LCA findings highlighted substantially higher environmental impacts (78–149 times) for LED systems, partly alleviated by PV-powered operations. Sensitivity analysis identified nutrient availability, process scale, and reactor costs as pivotal factors influencing the feasibility of LED-enhanced wastewater treatment. Overall, while LED technology offers notable productivity benefits, its economic and environmental trade-offs underscore the need for integrated approaches—ranging from material innovations to policy incentives—to achieve truly sustainable wastewater-based microalgal production.
- Modulating microalgal metabolism and its integration into dark fermentation: Challenges and opportunities with wastewater-grown biomassPublication . Ferreira, Jessica; Silva, Thiago; Saleme Aona de Paula Pereira, Alexia; Reis, Alberto; Zaiat, Marcelo; ; Calijuri, Maria LuciaABSTRACT: Microalgae represent a promising feedstock for the sustainable production of bioproducts and bioenergy, due to their versatile biochemical composition and environmental adaptability. Given the wide range of bioproducts that can be derived from their biomass, its biochemical composition suggests more favorable conversion routes and can be enhanced through cultivation conditions focused on the synthesis of one (or more) metabolites of interest to the biotechnology market. Accordingly, this review focuses on approaches for modulating microalgal metabolism, such as nutrient depletion and reactor configuration characteristics, among others, as well as on key outcomes obtained through two-stage cultivation, which combine phases of high biomass and metabolite productivity. From a resource recovery perspective, emphasis was placed on approaches that are more readily applicable to wastewater treatment plants. Furthermore, as energy-oriented routes are more suitable for valorizing of biomass grown in wastewater and considering that biohydrogen has been shown to be an emerging product of scientific relevance, this review also analyzes the limitations and strategies for integrating its production via dark fermentation. Pretreatment techniques and co-fermentation approaches were discussed as strategies to overcome the challenges associated with the anaerobic fermentation/digestion of microalgae due to their characteristics and biochemical composition. Finally, biorefinery configurations that integrate these processes were discussed from a scale-up perspective.
- Pilot-Scale cultivation of microalgae in blended effluents: C/N ratio management to boost biomass and biofuel precursorsPublication . Saleme Aona de Paula Pereira, Alexia; Silva, Thiago; Magalhães, Iara; Santos, Weller Gabriel da Silva; Oliveira, Mateus Soares de; Reis, Alberto; Couto, Eduardo de Aguiar; Calijuri, Maria LuciaABSTRACT: Algal biotechnology offers a sustainable pathway for wastewater treatment and resource recovery. However, the low carbon-to-nitrogen (C/N) ratio in domestic wastewater often limits microalgal productivity, which may compromise process viability and, consequently, limit its application in bioproduct valorization routes. This study evaluated the effects of blending municipal wastewater (MW) with industrial wastewater from juice processing (IWJ) at different ratios on biomass production, biochemical composition, and pollutant removal. Pilot-scale experiments in outdoor high-rate algal ponds, operated without external carbon dioxide (CO2) supply (relying on inorganic carbon present in the wastewater and passive diffusion from air). These experiments tested three blends: T1 (60 % MW + 40 % IWJ, C/N 9.25), T2 (40 % MW + 60 % IWJ, C/N 25.31), and T3 (20 % MW + 80 % IWJ, C/N 52.71). T1 achieved the highest biomass productivity and lipid content (14.44 %, p < 0.05), while T3 presented the highest levels of saturated fatty acids C16:0 (40.39 %) and C18:0 (10.08 %), supporting its biodiesel potential. Carbohydrate accumulation was enhanced in T2 (18.44 %) and T3 (21.09 %) under nitrogen-limited conditions. Microalgal species composition varied significantly with the C/N ratio, indicating selective adaptation. Additionally, dissolved organic carbon removal followed first-order kinetics across treatments, confirming model applicability. These findings underscore the effectiveness of effluent blending and C/N adjustment to enhance biomass quality, pollutant removal, and suitability for biofuel production in integrated algal-based wastewater treatment systems.