Browsing by Issue Date, starting with "2025-04"
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- Clustered patterns of household water consumption in Portuguese municipalities: do regional location and population trajectory matter?Publication . Jacinto, Gonçalo; Barreira, Ana PaulaPortugal faces water scarcity challenges, yet studies on per-household water consumption are limited. This study aims to address this gap by employing cluster analyses to assess how population trajectories, a previously overlooked aspect, and the regional location influence per-household monthly water consumption across 122 municipalities. Findings highlight higher consumption in the South despite lower prices. Municipalities experiencing population growth and those with long-term population declines show higher per-household water consumption but lower prices. Interestingly, while higher prices correlate with lower consumption, southern municipalities show increased prices without reduced consumption. Clustering reveals slight changes in consumption patterns from 2011 to 2020.
- Enhancing efficiency in solar non-intrusive desalination: solar still prototype optimization in Southwest EuropePublication . Pacheco, André; Sequeira, Claudia; Gomes Moreira da Silva, Manuela Fernanda; Serrão Sousa, VâniaAccess to freshwater is a pressing global challenge. Despite being irreplaceable freshwater is an increasingly scarce resource, especially in regions as Southern Europe, due to high human pressure and climate change. Solar desalination presents a low impact solution to produce freshwater from seawater, particularly in sun-rich regions. The main goal of this study was to develop a modular solar desalination system based on a non-intrusive approach, with simple assemblage, installation, and maintenance, to produce freshwater for non-potable purposes. The modular design was chosen to allow scalability and adaptability, enabling effective response to variable water demands in small island communities. The case study is a small island from Algarve, Portugal (Southwest Europe). The study evaluates the performance enhancements accomplished by transitioning from an initial prototype solar desalination unit, smaller and with a simple design, to an enhanced pilot-scale system designed to improve efficiency and water output. The research showed that both systems exhibit a high conductivity removal (higher than 99 %), demonstrating the potential of this technology to produce freshwater from seawater, delivering high-quality desalinated water, across different seasons. Prototype 1 demonstrated limited productivity, around 0.45 L/day.m2, while pilot-scale unit presented a productivity of approximately 6 L/day.m2 in summertime. This substantial improvement reflects the design modifications implemented in the pilot-scale unit, positioning it as a valuable option for water desalination in regions with abundant solar resources. These findings confirm the strong potential of solar desalination as a non-intrusive and effective solution and lays the groundwork for future advancements, focusing on maximising efficiency by exploring innovative materials to enhance solar energy absorption and optimizing operational conditions.
- Heterotrophic cultivation of Chlorella vulgaris yellow mutant on sidestreams: Medium formulation and process scale-upPublication . Trovão, Mafalda; Barros, Ana; Machado, Adriana; Reis, Ana; Pedroso, Humberto; Espírito Santo, Gonçalo; Correia, Nádia; Costa, Monya; Ferreira, Sara; Varela, João; Cardoso, Helena; Silva, Joana; Pereira, Hugo; Freitas, FilomenaMicroalgal protein is a promising feedstock to complement and/or replace other protein sources. Besides requiring less land and water usage, microalgae production is a more sustainable process, especially if industrial sidestreams are used as nutrient sources. Additionally, the heterotrophic cultivation of microalgae, such as Chlorella vulgaris, enables the achievement of much higher biomass productivity and lower areal footprint than autotrophic cultivation. Chlorophyll-deficient strains of C. vulgaris, as the yellow strain 7Y, provide microalgal biomass with improved sensory properties. In line with this, a waste-based medium was formulated to cultivate this strain, aiming at maximum biomass productivity. In this context, several industrial sidestreams were screened, and two food wastes and corn molasses were selected for their high nitrogen and glucose concentrations, respectively. The waste-based medium formulated was compared to the inorganic optimised medium at laboratory scale in Erlenmeyer flasks and 7-L reactors. The results obtained in the 7-L fermenters revealed that both conditions achieved similar biomass productivities and growth rates of approximately 14 g L-1 d-1 and 0.8 d-1, respectively. The biomass and protein productivities were further enhanced by supplying a higher nitrogen concentration in the feeding solution when the process was scaled-up to 200-L reactors, reaching 22 and 6.3 g L-1 d-1, respectively, thus validating the developed industrial waste-based medium for the efficient cultivation of C. vulgaris under heterotrophic conditions.