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Research Project
Development of agricultural bioproducts biofertilizers, biostimulants and biopesticides from piggery wastewater treatment-based microalgae
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Publications
Valorisation of microalga Tetradesmus obliquus grown in brewery wastewater using subcritical water extraction towards zero waste
Publication . Ferreira, Alice; Molnar Jazić, Jelena; Gouveia, Luisa; Maletić, Snežana; Tomić, Milan; Agbaba, Jasmina; Vladić, Jelena
n this study, green technology was applied for extraction of compounds from wastewater-grown microalga biomass with the final goal of obtaining microbiologically safe products within a sustainable biorefinery process with zero waste. Tetradesmus obliquus biomass resulting from brewery wastewater treatment, with (To-CO2) and without CO2 supplementation (To), was submitted to subcritical water extraction (SWE) at temperatures 120-220 degrees C for 10 min. The impact of the different SWE conditions in the obtained liquid extracts and solid residues were investigated for metal content and chemical and microbiological profiles. Gas chromatography-mass spectrometry analysis indicated that of T. obliquus extracts and residues are valuable sources of aliphatic saturated, unsaturated, and alkylated (mostly methylated) hydrocarbons, phenols, esters, and ketones. Polyphenolic content and antioxidant activity were enhanced approximately 4 times by increasing the temperature from 120 to 220 degrees C. Also, the content of polyphenols doubled when T. obliquus was supplemented with CO2 for all the tested temperatures (To: 0.249-1.016 mg GAE mL(-1); To-CO2: 0.437 - 1.767 mg GAE mL(-1)). The microbiological analysis determined that liquid extracts and residues represent safe sources of bioactive components that can be used in different industries. In addition, the lower content of heavy metals in residues suggests the possibility of using the solid waste as animal feed or soil conditioner in agricultural applications.
Supercritical CO2 extract from Microalga Tetradesmus obliquus: the effect of high-pressure pre-treatment
Publication . Vladić, Jelena; Jerković, Igor; Radman, Sanja; Molnar Jazić, Jelena; Ferreira, Alice; Maletić, Snežana; Gouveia, Luisa
High-pressure pre-treatment followed by supercritical carbon dioxide (ScCO2
) extraction (300 bar, 40 ◦C) was applied for the attainment of the lipophilic fraction of microalga Tetradesmus
obliquus. The chemical profile of supercritical extracts of T. obliquus was analyzed by ultra-highperformance liquid chromatography–high-resolution mass spectrometry with electrospray ionization
(UHPLC-ESI-HRMS). Moreover, the impact of ScCO2 on the microbiological and metal profile of the
biomass was monitored. The application of the pre-treatment increased the extraction yield approximately three-fold compared to the control. In the obtained extracts (control and pre-treated extracts),
the identified components belonged to triacylglyceroles, fatty acid derivatives, diacylglycerophosphocholines and diacylglycerophosphoserines, pigments, terpenes, and steroids. Triacylglycerols (65%)
were the most dominant group of compounds in the control extract. The pre-treatment decreased the
percentage of triacylglycerols to 2%, while the abundance of fatty acid derivatives was significantly
increased (82%). In addition, the pre-treatment led to an increase in the percentages of carotenoids,
terpenoids, and steroids. Furthermore, it was determined that ScCO2 extraction reduced the number
of microorganisms in the biomass. Considering its microbiological and metal profiles, the biomass
after ScCO2 can potentially be used as a safe and important source of organic compounds.
Algae as food in Europe: an overview of species diversity and their application
Publication . Mendes, Madalena; Navalho, Sofia; Ferreira, Alice; Paulino, Cristina; Figueiredo, Daniel; Silva, Daniel; Gao, Fengzheng; Gama, Florinda; Bombo, Gabriel; Jacinto, Rita; Aveiro, Susana; Schulze, Peter S.C.; Gonçalves, Ana Teresa; Pereira, Hugo; Gouveia, Luisa; Patarra, Rita F.; Abreu, Maria Helena; Silva, Joana L.; Navalho, João; Varela, João; Galileu Speranza, Lais
Algae have been consumed for millennia in several parts of the world as food, food supplements, and additives, due to their unique organoleptic properties and nutritional and health benefits. Algae are sustainable sources of proteins, minerals, and fiber, with well-balanced essential amino acids, pigments, and fatty acids, among other relevant metabolites for human nutrition. This review covers the historical consumption of algae in Europe, developments in the current European market, challenges when introducing new species to the market, bottlenecks in production technology, consumer acceptance, and legislation. The current algae species that are consumed and commercialized in Europe were investigated, according to their status under the European Union (EU) Novel Food legislation, along with the market perspectives in terms of the current research and development initiatives, while evaluating the interest and potential in the European market. The regular consumption of more than 150 algae species was identified, of which only 20% are approved under the EU Novel Food legislation, which demonstrates that the current legislation is not broad enough and requires an urgent update. Finally, the potential of the European algae market growth was indicated by the analysis of the trends in research, technological advances, and market initiatives to promote algae commercialization and consumption.
Exploring different pretreatment methodologies for allowing microalgae growth in undiluted piggery wastewater
Publication . Ferreira, Alice; Figueiredo, Daniel; Cardeiras, Rodrigo; Nabais, Rui; Ferreira, Francisca; Ribeiro, Belina; Cordovil, Cláudia M. d. S.; Acién, F. Gabriel; Gouveia, Luisa
The overapplication of manure on agricultural soils leads to nitrogen and phosphorus discharge into the aquatic environment, resulting in serious eutrophication problems and decreased water quality. Piggery wastewater (PWW) can be treated by microalgae to recycle nutrients, but the toxic levels of ammonia and organic matter hinder their growth. Fresh water is usually used to dilute PWW, but it is a scarce resource. The implementation of a pretreatment step before microalgae-based treatment could make PWW suitable for microalgae growth. Electrocoagulation, ammonia stripping, photo-Fenton, and constructed wetlands were evaluated as pretreatment methods to reduce ammonia, chemical oxygen demand (COD), color, and total suspended solids. Moreover, the pretreated PWWs were tested to grow the microalga Tetradesmus obliquus. Photo-Fenton showed the best results among the other pretreatments, achieving removal efficiencies above 90%, except for ammonia. This resulted in T. obliquus being capable of growing on undiluted PWW, even at higher ammonia levels, achieving similar biomass productivity to synthetic medium (66.4 ± 17.8 mg·L−1·day−1 and 60.1 ± 10.4 mg·L−1·day−1, respectively) almost doubling with pH control (116.5 mg·L−1·day−1). Thus, this pretreatment seems to be the most promising one to incorporate into microalgae-based treatment systems and must be further explored.
From piggery wastewater to wheat using microalgae towards zero waste
Publication . Ferreira, Alice; Figueiredo, Daniel; Ferreira, Francisca; Marujo, Ana; Bastos, Carolina; Martin-Atanes, Guillermo; Ribeiro, Belina; Štěrbová, Karolína; Marques-dos-Santos, Cláudia; Acién, F. Gabriel; Gouveia, Luisa
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.
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Funding agency
Fundação para a Ciência e a Tecnologia
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Funding Award Number
SFRH/BD/144122/2019