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Percorrer CCMAR por Objetivos de Desenvolvimento Sustentável (ODS) "07:Energias Renováveis e Acessíveis"
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- Assessment of cell disruption methods in an integrated multi-product biorefinery for Nannochloropsis Oceanica: from process design to economic analysis.Publication . Cunha, Pedro; Carvalho, Bernardo; Kholany, Mariam; Pereira, Hugo; Varela, JoãoMicroalgae are bioresources with significant potential within a sustainable, circular, bio-economy. However, high production costs have limited the widespread use of algae biomass. This study aimed to develop a multi-product biorefinery for Nannochloropsis oceanica that generates multiple revenue streams from the biomass, thereby enhancing the economic viability of algal production. The effectiveness of cell wall disruption using high-pressure homogenization and enzymatic hydrolysis was evaluated. Enzymatic hydrolysis solubilized nearly half (48.2 ± 1.5%) of the dry cell weight, compared to only 27.3 ± 3.2% with high-pressure homogenization, resulting in more concentrated water-soluble fractions and significantly higher protein extraction yields. Lipid extracts obtained after enzymatic hydrolysis had higher lipid (72.0 ± 5.3% w/w) and eicosapentaenoic acid (28.1 ± 6.9% w/w) contents than those from high-pressure homogenization (38.8 ± 6.1% w/w lipids; 9.1 ± 0.6% w/w eicosapentaenoic acid), despite similar lipid extraction yields (around 30%). Increasing the ethanol volumetric ratio from 58% to 75% v/v significantly improved lipid extraction yields (57.4 ± 3.1%) in the enzymatic hydrolysis-based biorefinery, with even higher yields observed upon scaling up (70.1%). All fractions, including lipid extracts, exhibited a balanced essential amino acid profile that exceeded the WHO/FAO/UNU-recommended values. A preliminary economic analysis indicated that lipid production was more cost-effective when cells were permeabilized by enzymatic hydrolysis than by high-pressure homogenization.
- Resources recovery from domestic wastewater by a combined process: anaerobic digestion and membrane photobioreactorPublication . Ferrera, Elvira; Ruigómez, Ignacio; Rebelo de Vela Bastos, Carolina; Ferreira, Alice; Gouveia, Luisa; Vera, LuisaAnaerobic and membrane technologies are a promising combination to decrease the energy consumption associated with wastewater treatment, allowing the recovery of resources: organic matter as biomethane, nutrient assimilation by microalgae and reclaimed water. In this study, domestic wastewater was treated using a combination of an upflow anaerobic sludge blanket sludge reactor (UASB) and a membrane photobioreactor (MPBR). The outdoor facilities were operated continuously for three months under unfavourable environmental conditions such as lack of temperature control, winter season with lower solar irradiation and lower daylight hours which was a challenge for the present work, not previously described. The energetic valorisation of the organic matter present in the wastewater by biomethane produced in the UASB would contribute to reducing overall facilities' energy requirements. The ultrafiltration (UF) membrane facilitated the harvesting of biomass, operating at 10 L·h-1·m-2 during the experimental period. Although the main contribution to fouling was irreversible, chemical cleanings were not necessary due to effective fouling control, which prevented the final TMP from exceeding 25 kPa. In addition, microalgae-bacterial consortium developed without prior inoculation were harvested from the MPBR using membrane assistance. The obtained biomass was also successfully tested as a biostimulant for corn germination/growth, as well as a biopesticide against Rhizoctonia solani and Fusarium oxysporum.