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Browsing UB - Artigos em revistas internacionais by Author "Acién, F. Gabriel"
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- Algaeculture for agriculture: from past to futurePublication . Ferreira, Alice; Bastos, Carolina R. V.; Santos, Cláudia Marques dos; Acién, F. Gabriel; Gouveia, LuisaABSTRACT: The continuous growth of the world population has imposed major challenges on agriculture. Consequently, farmers generalized the overuse of synthetic fertilizers and pesticides to meet the global food demand. Although these products have helped many developing countries increase their crop yield, they have simultaneously resulted in many issues, mainly the decline of soil fertility and degradation of local ecosystems due to soil, water, and air contamination, combined with their non-renewable nature and increased costs. For agriculture to become more sustainable, the use of alternative biological products, with recognized beneficial effects on plant yield and health, must be expanded. In this context, microalgae and cyanobacteria are rich sources of nutrients and bioactive metabolites, which have been gaining attention from researchers and companies for their ability to improve plant nutrition, growth, and tolerance to stress. This review gives an overview of the research work that has been done in the last two decades, regarding the use of microalgae and cyanobacteria (blue-green algae) as biofertilizers, biostimulants, and biopesticides. This work identified trends and challenges and highlights the use of microalgae to recycle the nutrients from wastewater to improve plant productivity while reducing the fertilizer and water footprint for more sustainable agriculture practices.
- Bioprocess to produce biostimulants/biofertilizers based on microalgae grown using piggery wastewater as nutrient sourcePublication . Ferreira, Alice; Corrêa, D. O.; Ribeiro, Belina; Silva, Teresa Lopes da; Santos, Cláudia Marques dos; Acién, F. Gabriel; Gouveia, LuisaABSTRACT: In the present work, two downstream processes - high-pressure homogenization at 100 (HPH-100) and 1200 bar (HPH-1200), and enzymatic hydrolysis (EH) - were tested to produce biostimulant extracts from Tetradesmus obliquus grown in piggery wastewater at two concentrations (12.8 and 88.3 g/L). Extracts before and after centrifugation (C) were evaluated in four bioassays using garden cress (germination), mung bean (auxin-like activity), and cucumber (auxin- and cytokinin-like activity) relative to distilled water. The initial microalgal culture, without any treatment, had the best germination results (162 % at 0.2 g/L) and the only one that showed cytokinin-like activity (141 % at 0.5 g/L). In both auxin-like bioassays, the HPH-1200 + C and EH + C originated high values (186 and 155 % for cucumber, 290 and 285 % for mung bean, respectively). For mung bean, the HPH-1200 achieved the highest auxin-like effect (378 %). Finally, the extracted biomass contained essential nutrients for biofertilization, complementing the biostimulant extracts for sustainable agriculture application.
- From piggery wastewater to wheat using microalgae towards zero wastePublication . Ferreira, Alice; Figueiredo, Daniel; Ferreira, Francisca; Marujo, Ana; Bastos, Carolina R. V.; Martin-Atanes, Guillermo; Ribeiro, Belina; Štěrbová, Karolína; Santos, Cláudia Marques dos; Acién, F. Gabriel; Gouveia, LuisaABSTRACT: Microalgae production is still expensive, driving the need to lower costs while strengthening the industry's environmental sustainability. Microalgae are recognized tools for efficient wastewater treatment, offering the recycling of nutrients and water for agriculture, and producing biomass rich in growth-promoting compounds to improve plant productivity and resistance to adverse conditions. The use of wastewater can reduce cultivation costs as it is a source of nutrients and water. Alternative low-cost methods can significantly decrease harvesting costs, which represents one of the most expensive steps of the whole process.The goal of this work was to evaluate the potential of wastewater-grown microalga biomass for agriculture purposes. To reduce production costs, the microalga Tetradesmus obliquus was produced in pre-treated photo-Fenton (PF) piggery wastewater in combination with the use of different harvesting techniques - electro-coagulation, flocculation, and centrifugation, and different combinations. From the wastewater treatment pro-cess, two fractions (biomass and supernatant) were evaluated for germination and growth of wheat (Triticum aestivum L.) plants and compared to non-harvested microalga culture (MC), distilled water, and Hoagland (synthetic) solution. The concentrated resulting from PF was also tested as a biofertilizer.The results confirm that both biomass and supernatants are useful for agricultural applications. The obtained biomass elicited a 20-105 % increase in germination index compared to the control, while supernatants were inhibiting. The opposite trend was observed at later stages of wheat growth, where the nutrient-enriched su-pernatants and the PF concentrate (PF-CC) increased the number of tillers (3-5) and leaves (30-42) after 83 days. Wheat plants treated with MC and PF-CC produced similar number of ears (3.4 & PLUSMN; 0.5 and 6.0 & PLUSMN; 4.1 ears per plant, respectively) than the synthetic control (5.7 & PLUSMN; 1.4) after 182 days. All fractions obtained from the process can be used in a zero-waste process.
- Innovative approach in sustainable agriculture: Harnessing microalgae potential via subcritical water extractionPublication . Ferreira, Alice; Vladic, Jelena; Corrêa, D. O.; Butzke, Valéria Louzada Leal; Martins, Pedro L.; Ribeiro, Belina; Santos, Cláudia Marques dos; Acién, F. Gabriel; Gouveia, LuisaABSTRACT: Microalgae can contribute to sustainable agriculture and wastewater treatment. This study investigated Tetradesmus obliquus, grown in piggery wastewater (To-PWW), as a biostimulant/biofertilizer compared to biomass grown in synthetic medium (To-B). Subcritical water extraction was tested for disruption/hydrolysis of wet biomass, at three temperatures (120, 170, and 220 °C) and two biomass loads (1:10 and 1:80 (g dry biomass/mL water)). Extracts were evaluated for germination, and root formation/expansion. Residues were quantified for nutrient composition to assess their biofertilizer potential and tested for their affinity to oil compounds for bioremediation. The best germination was achieved by To-B extracts at 170 °C (1:10: 148 % at 0.2 g/L, 1:80: 145 % at 0.5 g/L). Only To-PWW extracts at 0.2 g/L had a significant germination effect (120 °C: 120–123 % for both loads; 170 °C: 115 % for 1:80). To-PWW extract at 120 °C and 1:10 significantly affected cucumber and mung bean root formation (224 and 268 %, respectively). Most extracts significantly enhanced root expansion, with all To-B extracts at 1:10 showing the best results (139–181 %). The residues contained essential nutrients (NPK), indicating their biofertilizer potential, helping decrease synthetic fertilizers demands. To-B residues had high affinity to toluene and diesel but lower to used cooking and car oils. To-PWW showed very low affinity to all oil compounds. Finally, all residues were only able to form stable emulsions with the used car oil. This study fully exploits the use of microalgal biomass in sustainable agriculture, producing biostimulant extracts, and residues for biofertilizer and bioremediation, from a low-cost wastewater source.
- 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.