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- LCA: A tool to develop sustainable microalgal biorefineriesPublication . Caetano, N.S.; Corrêa, P.S.; Morais Júnior, W. G.; Mata, T.M.; Martins, A.A.A.; Branco Vieira, M.Microalgae biorefineries, similar to oil refineries, are planned to exploit and maximize the value of microalgae biomass, producing as many products as possible. The biorefinery flowsheet can take different configurations, depending on the target products and the technologies to be applied. Due to the diversity of microalgae composition and strain phenotypic plasticity, some constraints can be faced for choosing the ideal candidate species. However, there are several alternatives to explore the potentiality of a strain that can make the biorefinery economically viable, environmentally friendly, and socially acceptable. Life cycle assessment (LCA) is a tool that allows evaluating the environmental impacts of a product, process, or system, and should be used to assess the environmental performance of a planned biorefinery. When combined with life cycle costing (LCC) evaluation and social life cycle assessment (S-LCA), LCA allows to take informed decisions on the most adequate biorefinery to implement. Nevertheless, and although many of the processes used in microalgae-based biorefineries are common to those used in other well-established industries, the biorefinery is an emerging area where usually novel technologies are required, some of them applied only on a pilot or a laboratory scale, making the available data limited or highly sensitive to variations. This chapter discusses the application of LCA to biorefineries, the potential hurdles, and limitations.
- Symbiotic co-culture of Scenedesmus sp. and Azospirillum brasilense on N-deficient media with biomass production for biofuelsPublication . Contreras, José R.; Mata, Teresa M.; Cuellar-Bermudez, Sara P.; Caetano, Nídia S.; Chandra, Rashmi; Garcia-Perez, J. Saul; Muylaert, Koenraad; Parra-Saldivar, RobertoThe treatment of nitrogen-deficient agriculture wastewater, arising from the vegetable and fruit processing, is a significant problem that limits the efficiency of its biological treatment. This study evaluates the effectiveness of the symbiotic co-culture of Azospirillum brasilense and Scenedesmus sp., under two nitrogen levels (8.23 mg L−1 and 41.17 mg L−1) and mixing systems (aeration and magnetic stirring), aiming to simultaneously use the N-deficient media for their growth while producing biomass for biofuels. Microalgae growth and biomass composition, in terms of protein, carbohydrate and fatty acid contents, were evaluated at the end of the exponential growth phase (15 days after inoculation). Results show that the symbiotic co-culture of microalgae-bacteria can be effectively performed on nitrogen-deficient media and has the potential to enhance microalgae colony size and the fatty acid content of biomass for biofuels. The highest biomass concentration (103 ± 2 mg·L−1) was obtained under aeration, with low nitrogen concentration, in the presence of A. brasilense. In particular, aeration contributed to, on average, a higher fatty acid content (48 ± 7% dry weight (DW)) and higher colony size (164 ± 21 µm2) than mechanical stirring (with 39 ± 2% DW and 134 ± 21 µm2, respectively) because aeration contribute to better mass transfer of gases in the culture. Also, co-culturing contributed in average, to higher colony size (155 ± 21 µm2) than without A. brasilense (143 ± 21 µm2). Moreover, using nitrogen deficient wastewater as the culture media can contribute to decrease nitrogen and energy inputs. Additionally, A. brasilense is approved and already extensively used in agriculture and wastewater treatment, without known environmental or health issues, simplifying the biomass processing for the desired application.
- Sustainable energy and biorefineries from biowastesPublication . Caetano, Nídia; Balu, Alina M.; Costa, Mário; Gouveia, Luisa; Parthiba Karthikeyan, Obulisamy; Mata, TeresaWhile renewable energy is usually considered environmentally friendly, its sustainability must be demonstrated, especially when produced from biomass sources. Moreover, there is an ongoing effort towards the development of increasing circular economy models, instead of the conventional linear economy models. This movement has opened new opportunities for the sustainable production of energy from various sources, in particular from biowaste resulting from food production and consumption, a significant source of waste that needs to be properly treated instead of disposed of. This special issue of Sustainability, with the theme Sustainable Energy and Biorefineries from Biowastes, aims to publish research or review articles dealing with the energy valorization of biowaste from various sources, mainly for producing energy or energy carriers.
- Life cycle analysis of a particleboard based on cardoon and starch/chitosanPublication . Mata, Teresa Margarida; Freitas, Clara; Silva, Gabriela Ventura; Monteiro, Sandra; Martins, Jorge Manuel; Carvalho, Luísa Hora de; Silva, Luís Manuel; Martins, Antonio AreosaThis work analyzes the life cycle environmental impacts of producing a particleboard based on cardoon fibers and a starch/chitosan adhesive from a “cradle-to-gate” perspective, considering the following life cycle steps: raw material production, adhesive preparation (component mixing and heating), cardoon fiber preparation (crushing and sieving), adhesive and fiber mixing, hot-pressing and final processing. The functional unit is a particleboard with the dimensions of 220 × 220 × 16 mm3. For the life cycle inventory, experimental data obtained from the production of particleboard on a pilot scale were used. The Aspen Plus V9 software was used to simulate the heating process in the manufacture of the biological adhesive and obtain the data associated with this stage. Portuguese or European conditions were considered for the background processes, using data from the EcoInvent V3.5 LCI database. The environmental impacts were quantified using the RECIPE methodology. To complement the study, the VOCs present in the panel were analyzed using the “active headspace” technique. The results show that for most of the environmental impact categories, energy consumption is dominant, followed by starch and chitosan production. Using fully renewable electricity produced in photovoltaic panels, instead of the Portuguese electricity mix, significantly reduces the impacts in most of the environmental impact categories, for example, the carbon footprint is reduced by 34%. Future studies will analyze how the environmental impacts can be further reduced, and how process scale-up may influence them.
- Microalgae for pigments and cosmeticsPublication . Caetano, Nídia S.; Corrêa, Priscila S.; Morais Júnior, Wilson G. de; Oliveira, Gisela M.; Martins, Antonio A.A.; Branco-Vieira, Monique; Mata, Teresa M.Microalgae are among the most promising cell factories of the near future. Their renewable nature, and ability to rely on photosynthesis to use CO2 or nutrients from wastewater to grow and multiply, make them an emergent source of valuable natural compounds. Although in the past, a few of these microalgae have been known for their value as a source of proteins, carbohydrates, exopolysaccharides, polyunsaturated fatty acids, omega 3 and omega 6 fatty acids, recently they have also been found increasingly important sources of more valuable compounds such as carotenoids, of which astaxanthin, lutein and β-carotene are of extreme importance in food, feed and cosmeceutical industries, and phycobiliproteins, chlorophylls, that are finding their place in the commercial market. There are still various challenges to be addressed to make sustainable the production of some of these valuable bioproducts. However, the circular economy and the biorefinery approach are at the center of the whole process to make the microalgae-based industry one of the most dynamic, modern and profitable industries. In this chapter it will be presented the potential microalgae sources of these valuable compounds, existing industrial applications, as well as the major ongoing research projects, and their contribution driving the blue bioeconomy.