Browsing by Issue Date, starting with "2025-03"
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- Piggery wastewater treatment by solar photo-Fenton coupled with microalgae productionPublication . Ferreira, Alice; Attar, Solaima Belachqer-El; Villaro-Cos, Silvia; Ciardi, Martina; Soriano-Molina, Paula; López, Jose Luis Casas; Lafarga, Tomás; Santos, Cláudia Marques dos; Acién, F. Gabriel; Gouveia, LuisaABSTRACT: Pig farming generates highly polluted wastewater that requires effective treatment to minimize environmental damage. Microalgae can recover nutrients from piggery wastewater (PWW), but excessive nutrient and turbidity levels inhibit their growth. Solar photo-Fenton (PF) offer a sustainable and cost-effective pretreatment to allow microalgal growth for further PWW treatment. This study optimized the concentrations of PF reagents to minimise water and nutrient inputs while maintaining microalgae-based treatment efficiency. PF trials were conducted in pilot-scale raceway ponds under solar radiation, testing different concentrations of FeSO4 (4.48 and 8.95 mM) and H2O2 (77, 154, and 309 mM). Following PF, Tetradesmus obliquus was used in a biological treatment of PWW to recover the remaining nutrients. PF achieved high removal efficiencies for turbidity (97.6-99.5 %), total organic carbon (59.2-77.1 %), and chemical oxygen demand (83.8-94.7 %), but ammonium was not significantly removed. Phosphorus was almost completely removed through iron precipitation during neutralisation. Lowering the H2O2 concentration from 309 to 77 mM did not compromise removal efficiency but reducing FeSO4 below 8.95 mM negatively affected the process. Consequently, 8.95 mM FeSO4 and 77 mM H2O2 were selected for microalgae production. The pretreated PWW could be recycled at least once for microalgal production, without nutrient supplementation, improving biomass productivity and PWW treatment, especially targeting ammonium. Phosphorus supplementation, however, did not significantly boost biomass productivity or treatment efficiency. Moreover, the iron sludge generated from PF pretreatment contained enough NPK to be repurposed as an organic fertilizer boosting sustainable agricultural practices. These findings encourage further investigation of this emerging combined technology towards wastewater treatment at large-scale.
- Detection of corrosion on silvered glass reflectors via image processingPublication . Wiesinger, Florian; Baghouil, Sarah; Le Baron, Estelle; Collignon, Romain; Santos, Filipa; Cunha Diamantino, Teresa; Catarino, Isabel; Facão, Jorge; Ferreira, Cristina; Páscoa, Soraia; Sutter, Florian; Fernández-García, Aránzazu; Wette, JohannesABSTRACT: A novel characterization technique based on image analysis is presented, intended to complement state-of-the-art reflectometer measurements. The technique is developed by experts from different laboratories (OPAC, AGC, CEA and LNEG), which subsequently conduct two Round Robin experiments on corroded solar reflectors for validation. Regarding the inter-comparability, it is found that parameters like the corrosion spot density or the penetration maximum on coated edges exhibit an average coefficient of variation of 62.6 % and 54.9 %. Better agreement is found for parameters like the total corroded area and the maximum edge corrosion penetration, with coefficients of variation of 14.3 % and 13.4 %, respectively. The developed methodology is further applied during a 68-month lasting outdoor exposure campaign of two types of solar reflectors at two representative sites, one exhibiting corrosivity class C2 and the other C3. On the commercial coating RL1, a total corroded area of 59 mm2 and 426 mm2 is measured after the outdoor exposure on the C2 and the C3 site, respectively, while on the novel low-lead coated reflector RL3 corresponding values are 280 mm2 and 1308 mm2. This shows the superior quality of the coating RL1 in terms of corrosion resistance. Furthermore, the analysis highlights the importance of proper edge sealing for corrosion protection, since corrosion penetration is increased by a factor between 1.3 and 4.0 if the edges are unprotected. The reflectance decrease after the outdoor exposure is regarded as negligible (0.000 - 0.005), thus not permitting any of the conclusions that are made from the novel image analysis technique.
- LNEG-LCOH - Calculadora do Custo Nivelado do Hidrogénio: Descrição e Relatório MetodológicoPublication . Portillo, Juan C. C.; Simoes, SofiaRESUMO: Este documento descreve a metodologia utilizada para a implementação da ferramenta LNEG-LCOH versão 01.2024, a descrição dos módulos, incluindo exemplos de uso e valores de referência. O objetivo da LNEG-LCOH - Calculadora do Custo Nivelado do Hidrogénio (ferramenta LNEG-LCOH) é fornecer um serviço gratuito para a estimativa rápida dos custos em diferentes componentes da cadeia de valor do hidrogénio. A ferramenta está pensada para proporcionar flexibilidade de acordo com as necessidades dos utilizadores e fornecer valores referenciais com base nas tendências atuais. Espera-se que a ferramenta evolua ao longo do tempo para considerar mais componentes e satisfazer as necessidades que possam surgir dos utilizadores.
- LNEG-LCOH - Levelised Cost of Hydrogen Calculator: Description and Methodological ReportPublication . Portillo, Juan C. C.; Simoes, SofiaABSTRACT: This document describes the methodology used for the implementation of the LNEG-LCOH tool version 01.2024, the description of the modules, including examples of use and reference values. The purpose of the LNEG-LCOH - Levelised Cost of Hydrogen Calculator (LNEG-LCOH Tool) is to provide a free service for the quick estimation of costs over different components of the hydrogen’s value chain. The tool is envisioned to provide flexibility according to the needs of the users and to provide referential values based on current trends. It is expected the tool will evolve over time to consider more components and to satisfy needs that may arise from users.
- Opportunities and challenges in a world-class mining district, the Iberian Pyrite BeltPublication . Castelo Branco, José M.ABSTRACT: A summary is made on the exploration work carried out in the Iberian Pyrite Belt (IPB) and an attempt is made to describe the evolution of the exploration methods and strategies applied in the field which led to the discovery of the main deposits. Finally, a reference is made to the good potential for new discoveries in the IPB, giving clues about new exploration models to be pursued. Being undoubtedly a world-class metallogenic province, the IPB naturally deserves a special mention regarding the mining history and on the evolution of the exploration techniques, adjusted to the new paradigms, namely in the need to search at ever greater depths. The most recent cases of successful new discoveries in the IPB are described, largely resulting from the refining of geological, geophysical and geochemical prospecting methodologies, and clues that are expected to lead to the discovery of new concealed deposits are equated.
- Benchmarking commercially available value-added fractions with potential for production via microalgae-based biorefineries: is it worth it?Publication . Ferreira, Flávio; Reis, Alberto; Ortigueira, Joana; Lopes, TiagoABSTRACT: The urgent need to mitigate climate change requires finding sustainable and efficient alternatives to fossil fuel-based materials. Biosequestration by microalgae has been suggested as a potential method for climate change mitigation due to its environmentally friendly nature and ability to produce high-value compounds. However, the large-scale application of microalgal biorefineries faces significant challenges, particularly in the harvest and processing stages, which are often costly and energy-intensive. This study aims to benchmark value-added fractions that can be produced via microalgae-based biorefineries against their commercially available counterparts. A systematic review was conducted using the Web of Science™ database to identify current commercial sources of proteins, lipids, polyunsaturated fatty acids and pigments, this study identified key sectors and applications for each fraction, as well as potential market competitors. The results highlight substantial cost differences across production systems, with traditional agricultural sources demonstrating lower CAPEX but greater environmental challenges. Meanwhile, microalgal systems, although associated with higher CAPEX, offer advantages such as reduced land and water dependency, potentially leading to long-term economic resilience and environmental sustainability. By pinpointing research trends, key sectors and optimization opportunities, this work offers valuable insights into the profitability and competitiveness of microalgal systems, providing a benchmark for future optimization efforts. The novelty of this research lies in its comprehensive comparison of microalgae-based and traditional production systems, establishing a clear benchmark for microalgal production and suggesting focus areas for enhancement.
- Thermoelectric Properties of Tetrahedrites Produced from Mixtures of Natural and Synthetic MaterialsPublication . Santos, Beatriz; Esperto, Luís; Figueira Vasques, Isabel; Mascarenhas, João; Lopes, E.B.; Salgueiro, Rute; Silva, Teresa; Correia, Jose B.; de Oliveira, Daniel Pipa Soares; Pereira Gonçalves, Antonio; Neves, FilipeABSTRACT: Thermoelectric materials have considerable potential in the mitigation of the global energy crisis, through their ability to convert heat into electricity. This study aims to valorize natural resources, and potentially reduce production costs, by incorporating tetrahedrite-tennantite (td) ores from the Portuguese Iberian Pyrite Belt into synthetic samples. The ore samples were collected in a mine waste at Barrig & atilde;o and as "dirty-copper" pockets of ore from the Neves Corvo mine. Subsequently, high-energy ball milling and hot pressing were employed in the production of thermoelectric materials. These are characterized by XRD, SEM/EDS, and thermoelectrical properties. The complete dissolution of the dump material sulfides with the synthetic tetrahedrite constituents led to an increase in the amount of the tetrahedrite-tennantite phase, which was made up of a tetrahedrite-tennantite-(Fe) solid solution. The thermoelectric characterization of these materials is provided, revealing that most of the combined synthetic ore samples displayed better results than the pristine tetrahedrite, mostly due to higher Seebeck coefficient values. Furthermore, the best thermoelectric performance is achieved with 10% of ore, where a power factor of 268 mu W.K-2.m-1 is reached at room temperature.
- A Machine Learning Model for Procurement of Secondary Reserve Capacity in Power Systems with Significant vRES PenetrationsPublication . dos Santos, Joao; Algarvio, HugoABSTRACT: The growing investment in variable renewable energy sources is changing how electricity markets operate. In Europe, players rely on forecasts to participate in day-ahead markets closing between 12 and 37 h ahead of real-time operation. Usually, transmission system operators use a symmetrical procurement of up and down secondary power reserves based on the expected demand. This work uses machine learning techniques that dynamically compute it using the day-ahead programmed and expected dispatches of variable renewable energy sources, demand, and other technologies. Specifically, the methodology incorporates neural networks, such as Long Short-Term Memory (LSTM) or Convolutional neural network (CNN) models, to improve forecasting accuracy by capturing temporal dependencies and nonlinear patterns in the data. This study uses operational open data from the Spanish operator from 2014 to 2023 for training. Benchmark and test data are from the year 2024. Different machine learning architectures have been tested, but a Fully Connected Neural Network (FCNN) has the best results. The proposed methodology improves the usage of the up and down secondary reserved power by almost 22% and 11%, respectively.
- 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.
- A new species of Acitheca (Psaroniaceae, Marattiales) with exceptionally and three-dimensionally preserved sporangia from the Buçaco Carboniferous Basin, western central PortugalPublication . Correia, Pedro; Pereira, Sofia; Šimunek, Zbynek; Sá, Artur A.; Pereira, ZéliaABSTRACT: A new fern fossil-species Acitheca machadoi sp. nov. is erected under the family Psaroniaceae (Marattiales), based on adpression fossil remains of fertile foliage from the Monsarros Formation (upper Stephanian C, upper Gzhelian) of the Buçaco Carboniferous Basin, in western central Portugal. Acitheca machadoi comprises relatively narrow and long fertile pinnules bearing exceptionally and three-dimensionally preserved sporangia with in situ spores. These sporangia are elongate (fusiform) and one of the smallest documented for the genus, with a triangular pyramid-like shape in the upper part and rounded to hexagonal-like attachment base. Its occurrence within an assemblage dominated by mesophytes to hygrophytes, with fewer drought-tolerant forms, suggests a wetland environment with a seasonal climate, framed in the transition from humid to dry conditions in western Iberia during the Late Pennsylvanian–early Permian. This palaeobotanical finding provides new insights on the palaeoecology and species diversity of Acitheca, whose currently known fossil record is certainly underestimated.