Bioenergia - UB
Permanent URI for this community
Browse
Browsing Bioenergia - UB by Author "Acien, Gabriel"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- Biostimulant potential of Scenedesmus obliquus grown in brewery wastewaterPublication . Navarro-Lopez, Elvira; Ruiz-Nieto, Angela; Ferreira, Alice; Acien, Gabriel; Gouveia, LuisaABSTRACT: Microalgae are microorganisms with the capacity to contribute to the sustainable and healthy food production, in addition to wastewater treatment. The subject of this work was to determine the potential of Scenedesmus obliquus microalga grown in brewery wastewater to act as a plant biostimulant. The germination index of watercress seeds, as well as the auxin-like activity in mung bean and cucumber, and in the cytokinin-like activity in cucumber bioassays were used to evaluate the biostimulant potential. Several biomass processes were studied, such as centrifugation, ultrasonication and enzymatic hydrolysis, as well as the final concentration of microalgal extracts to determine their influence in the biostimulant activity of the Scenedesmus biomass. The results showed an increase of 40% on the germination index when using the biomass at 0.1 g/L, without any pre-treatment. For auxin-like activity, the best results (up to 60% with respect to control) were obtained at 0.5 g/L of biomass extract, after a combination of cell disruption, enzymatic hydrolysis and centrifugation. For cytokinin-like activity, the best results (up to 187.5% with respect to control) were achieved without cell disruption, after enzymatic hydrolysis and centrifugation at a biomass extract concentration of 2 g/L.
- Exploring different pretreatment methodologies for allowing microalgae growth in undiluted piggery wastewaterPublication . Ferreira, Alice; Figueiredo, Daniel; Cardeiras, Rodrigo; Nabais, Rui; Ferreira, Francisca; Ribeiro, Belina; Cordovil, Cláudia; Acien, Gabriel; Gouveia, LuisaABSTRACT: 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.
- The role of microalgae in the bioeconomyPublication . Acien, Gabriel; Reis, Alberto; Wijffels, René H.; Barbosa, Maria; Verdelho, Vitor; Llamas, BernardoABSTRACT: The bioeconomy is a new and essential paradigm for reducing our dependence on natural resources and responding to the environmental threats that the Earth is currently facing. In this regard, microalgae offer almost unlimited possibilities for developing a modern bioeconomy given their metabolic flexibility and high biomass output rates, even when produced under harsh conditions, such as when treating wastewaters or using flue gases. In this article, the microalgal contribution to important economic activities such as the production of food and feed, cosmetics and health-related compounds is reviewed. Moreover, potential contributions of microalgae to emerging sectors are discussed, as in the production of biomaterials, agriculture-related products, biofuels and provision of services such as wastewater treatment and the clean-up of industrial gases. The different microalgal production technologies have also been analyzed to identify the main bottlenecks affecting microalgal use in different applications. Finally, the major challenges facing microalgal biotechnology in enlarging its contribution to the bioeconomy are evaluated, and future trends discussed.