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- Monitoring C. vulgaris Cultivations Grown on Winery Wastewater Using Flow CytometryPublication . Lopes da Silva, Teresa; Silva, Thiago; França, Bruna Thomazinho; Ribeiro, Belina; Reis, AlbertoABSTRACT: Winery wastewater (WWW), if released untreated, poses a serious environmental threat due to its high organic load. In this study, Chlorella vulgaris was cultivated in diluted WWW to assess its suitability as a culture medium. Two outdoor cultivation systems-a 270 L raceway and a 40 L bubble column-were operated over 33 days using synthetic medium (control) and WWW. A flow cytometry (FC) protocol was implemented to monitor key physiological parameters in near-real time, including cell concentration, membrane integrity, chlorophyll content, cell size, and internal complexity. At the end of cultivation, the bubble column yielded the highest cell concentrations: 2.85 x 106 cells/mL (control) and 2.30 x 106 cells/mL (WWW), though with lower proportions of intact cells (25% and 31%, respectively). Raceway cultures showed lower cell concentrations: 1.64 x 106 (control) and 1.54 x 106 cells/mL (WWW), but higher membrane integrity (76% and 36% for control and WWW cultures, respectively). On average, cells grown in the bubble column had a 22% larger radius than those in the raceway, favouring sedimentation. Heterotrophic cells were more abundant in WWW cultures, due to the presence of organic carbon, indicating its potential for use as animal feed. This study demonstrates that FC is a powerful, real-time tool for monitoring microalgae physiology and optimising cultivation in complex effluents like WWW.
- Fractionation of macroalgae carbohydrates using hydrothermal and dilute inorganic salt pretreatments to produce oligosaccharides and furansPublication . Martins, Pedro L.; Andrade, Cristiana; Duarte, Luís; Reis, Alberto; Pereira, Helena; Carvalheiro, FlorbelaABSTRACT: Furans are among the most important compounds derived from biomass, providing conversion pathways for sustainable alternatives to petroleum-based fuels and materials. Furfural, 5-hydroxymethylfurfural (5-HMF), and 5-methylfurfural (5-MF) are furans that can be obtained by carbohydrate dehydration under acidic conditions at elevated temperature and pressure. One of the mechanisms to produce these compounds from lignocellulosic materials relies on prior fractionation of biomass carbohydrates and further dehydration catalysis. However, this is a costly and technically challenging method and it would be advantageous to develop a one-pot conversion mechanism that facilitates simultaneous biomass fractionation and conversion to furans. Ulva lactuca is an alga that has the advantage of being lignin-free and rich in glucose, rhamnose, and xylose, which are ideal for producing 5-HMF, 5-MF, and furfural, respectively. The high diversity of sugar constituents is also relevant for the production of added-value oligosaccharides. Catalysis with inorganic salts has been reported as a successful tool for biomass upgrading to furans when combined with hydrothermal pretreatments, and could provide a cheap and environmentally friendly one-step methodology for furan production. This study therefore aimed to investigate the effect of hydrothermal and dilute acid pretreatments, as well as treatment with inorganic salt solutions (ferric chloride, ferric nitrate, and aluminium nitrate) on U. lactuca biomass to produce oligosaccharides, monosaccharides, and furans (furfural, 5-HMF, and 5-MF). These methods resulted in a maximum sugar solubilization of 65% in non-salt-assisted hydrothermal pretreatments and 84% in salt-assisted hydrothermal pretreatments, with inorganic salt catalysis also resulting in 100% xylose, 36% glucose, and 46% rhamnose conversion to the respective furans.
- Integrating social aspects in microalgal biorefineries: a Product Social Impact Life Cycle Assessment (PSILCA) approachPublication . Ortigueira, Joana; Lopes, Tiago; Reis, Alberto; Gírio, FranciscoABSTRACT: The ongoing climate change phenomenon requires the reduction of atmospheric CO2 concentrations. Microalgal biorefineries, which convert atmospheric CO2 into chemical energy, offer a viable alternative to fossil fuel-based industrial systems. This study assesses the social impacts of microalgal biorefineries using the Product Social Impact Life Cycle Assessment database approach, focusing on an industrial facility located in P & oacute;voa de Santa Iria, Vila Franca de Xira, Portugal. The foreground system involves the production of microalgae in cascade raceway systems, followed by their refinement into protein, lipid and carbohydrate fractions. Dedicated surveys were distributed to the local community to collect social data, which was then analyzed using the Product Social Impact Life Cycle Assessment (PSILCA) database and a newly designed evaluation schema. Preliminary data from approximately 300 valid responses indicated that the local community faces a medium risk of being unfamiliar with the concept of microalgae or its benefits but acknowledged the high probability of local economic benefits and job creation upon implementation. The study highlights a general lack of familiarity with microalgae among the local community, which could affect the acceptance of the biorefinery. Although the PSILCA approach identifies social hotspots effectively, reliance on generic data may not accurately represent the local context. The study underscores the need for enhanced information dissemination to improve community acceptance and support for microalgal biorefineries. Preliminary data collection and analysis highlight the potential for social benefits, but further research is required to address the identified limitations.
- Como o trabalho do LNEG apoia a concretização do PNEC: Plano Nacional de Energia e Clima - Conheça 10 dos trabalhos do LNEG que contribuem para a concretização do PNECPublication . Simoes, Sofia; Simões, Teresa; Barbosa, Juliana Pacheco; Rodrigues, Carlos; Azevedo, Pedro; Cardoso, João; Facão, Jorge; Costa, Paula Silva; Justino, Paulo Alexandre; Gírio, Francisco; Reis, Alberto; Passarinho, Paula; Duarte, Luís; Moura, Patrícia; Abreu, Mariana; Estanqueiro, Ana; Couto, António; Oliveira, Paula; Quental, Lídia; Patinha, Pedro; Catarino, Justina; Picado, Ana; Ramalho, Elsa; de Oliveira, Daniel Pipa Soares; Filipe, Augusto; Albardeiro, Luís; Santos, Sara; Gonçalves, Pedro
- 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.
- 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.
- 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.