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Bioenergia - UB

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http://hdl.handle.net/10400.9/22

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Percorrer Bioenergia - UB por Objetivos de Desenvolvimento Sustentável (ODS) "06:Água Potável e Saneamento"

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  • Enhancing microalgal biohydrogen production: Unlocking higher yields with hydrothermal pretreatment with niobium phosphate
    Publication . Silva, Thiago; Jesus Junior, Maurino Magno; Neves de Araujo, Matheus; Castro, Laressa Santos; Fuess, Lucas Tadeu; Rodrigues, Fábio de Ávila; Zaiat, Marcelo; Reis, Alberto; Calijuri, Maria Lucia
    ABSTRACT: Microalgae cultivated in wastewater hold promise as a substrate for biohydrogen (bioH2) production. However, their rigid cell walls pose a challenge to fermentability. In this context, this study evaluated hydrothermal pretreatment with niobium phosphate (NbP) at 100-180 degrees C for 0-70 min, using up to 75 % NbP (relative to the dry weight of microalgal biomass). The hydrothermal pretreatment at 180 degrees C for 10 min with 75 % NbP released 7431 mg total carbohydrates (CHt) L-1, increasing the availability of fermentable substrates in subsequent dark fermentation (DF). When this pretreated biomass was subsequently fermented at pH 5.0 (sample PB5), bioH2 production reached 1.03 mmol H2 mol-1 CHt, with a maximum cumulative output of 0.17 mmol H2 and a CHt conversion efficiency of 83.6 %. In contrast, pH 5.5 and 6.0 reduced bioH2 yields and promoted methanogenic activity, while no pH control resulted in negligible bioH2 evolution. In conclusion, hydrothermal pretreatment with niobium phosphate and pH improvement synergize to enhance hydrogenogenesis, integrating wastewater treatment and renewable biohydrogen production.
    2026-03Artigo científico Acesso aberto Ver mais
  • Reducing nutrient requirement using nitrogen-fixing bacteria for microalgae cultivation
    Publication . Melkonyan, Lusine; Ferreira, Alice; Bastos, Carolina R. V.; Figueiredo, Daniel; Lopes da Silva, Teresa; Avetisova, Gayane; Karapetyan, Zh.; Toplaghaltsyan, A.; Gouveia, Luisa
    ABSTRACT: In environments, microalgae have been observed to coexist with bacteria. Different nitrogen-fixing bacteria (NFB) were isolated from Armenian soils and their growth was evaluated in co-cultivation with the microalga Tetradesmus obliquus and cyanobacteria Synechocystis sp. PCC 6803. The most effective mutualistic consortium was T. obliquus-NFB5 (Sphingobacterium sp. L13G8). This resulted an increase in both populations, chlorophyll fluorescence, biomass protein, carbohydrate content, an effect on lipid metabolism, without the need for external nitrogen. The findings demonstrated the significance of employing NFB for microalga growth, as they facilitate the essential nitrogen provision in N-free Bristol medium. Moreover, in mutualistic consortia, microalgae facilitate the exudation of dissolved organic carbon and O2 to bacteria, which, in turn, become available for bacteria, thereby reducing the necessity for energy-consuming aeration processes in co-cultivation. In return, the bacteria provide the microalgae with CO2, B vitamins and demineralize N2, P, S, thereby further supporting the growth of microalgae.
    2025-09Artigo científico Acesso aberto Ver mais