Laboratory for Process Engineering, Environment, Biotechnology and Energy

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Publications

Symbiotic co-culture of Scenedesmus sp. and Azospirillum brasilense on N-deficient media with biomass production for biofuels

Publication . Contreras, José R.; Mata, Teresa M.; Cuellar-Bermudez, Sara P.; Caetano, Nídia S.; Chandra, Rashmi; Garcia-Perez, J. Saul; Muylaert, Koenraad; Parra-Saldivar, Roberto

The 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.

2019Journal article

Open access

Strategies for Enhancing Soil Phytoremediation and Biomass Valorization

Publication . Marques, Ana P. G. C.; Caetano, Nídia; Castro, Paula M. L.

The information available in the literature on options for biofuel production from biomass derived from the phytoremediation of metal-contaminated soils is scarce; however, the existing studies have reported a considerable degree of success. In addition to the described advantages for energy production, it is important to remember that the production of biomass in such as soil erosion control through the establishment of a plant cover in an otherwise barren soil, carbon dioxide sequestering by the established crops or environmental justice through compliance with the law by owners of polluted land. Therefore, it seems that this can be an important research pathway to follow. It is important to state that the HM soil remediation process does not end with the phytoremediation and subsequent harvesting of the implemented crops and sometimes not even at the end of the processing for biomass conversion into energy, as metals are non-degradable elements. However, some of these proposed alternatives offer a safe way to turn a potentially harmful residue into a useful resource.

2020Book part

Restricted access

Evaluation of Areca palm renewable options to replace disposable plastic containers using life cycle assessment methodology

Publication . Gautam, Anirudh; Mata, Teresa M.; Martins, António A.; Caetano, Nídia

In spite of raising awareness of the environmental impacts associated to the production and utilization of plastics, in many situations, the use of plastics is advantageous, and options are still unavailable or under development, representing an opportunity to develop more sustainable options, such as less energy intensive solutions. In this work, the LCA methodology is used to evaluate the environmental impacts of boxes, bowls and plates produced using Areca palm (Areca catechu) sheath, a waste material common in southern India. The inventory is a combination of primary data from a company in India, complemented with secondary data from the Ecoinvent v2.1 (Simapro V7.3). Results show that the main contributors to the potential environmental impact categories and the most energy intensive life cycle steps, are transportation, shipping and electricity generation. Carbon footprints of 1180, 1033 and 1090 kg CO2eq/ton were obtained for Areca boxes, plates and bowls, respectively. Plates made from Areca palm sheath have lower environmental impacts than plastic plates, except in the ozone layer depletion and terrestrial toxicity impact categories.

2019Conference object

Open access