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Research Project
Mechanical Engineering and Resource Sustainability Center
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Publications
A circular approach for landfill leachate treatment: chemical precipitation with biomass ash followed by bioremediation through microalgae
Publication . Viegas, Catarina; Nobre, Catarina; Mota, André; Vilarinho, Cândida; Gouveia, Luisa; Gonçalves, Maria Margarida
ABSTRACT: The aim of this work was to study an integrated approach for landfill leachate remediation comprising chemical precipitation with biomass bottom ash as a pre-treatment to reduce color and turbidity followed by bioremediation through microalgae treatment for effluent disposal. Optimal pre-treatment conditions were determined through batch experiments and were found to be 160 g L-1 ash dose, 96 h of contact time, overhead agitation at 15 rpm and ash particle size below 500 mu m. These conditions led to removal efficiencies of 74.3% for chemical oxygen demand and 98.5% for color. Large quantities of sludge containing excess biomass ash and precipitated compounds were formed during the pre-treatment. To minimize solid disposal, this sludge was tested as a raw material for cementitious and aggregate substitute in mortar formulations. Following the pre-treatment, the leachate was inoculated with six different microalgae species to evaluate their ability to grow in such a recalcitrant effluent and remediate it. After a period of 27 days biomass concentration from 0.4 to 1.2 g L-1 were achieved for the tested microalgae. Removal efficiencies were in the range of 18-62% for COD, 63-71% for N, and 15-100% for P. At the end of the treatment, algal biomass was characterized regarding protein, lipid, fatty acids, carbohydrate, and ash contents. This approach allows a low-cost remediation of these recalcitrant effluents when compared with the present options that include inverse osmosis, and the valorization of ash-rich precipitates and microalgae biomass improves the sustainability of the overall process.
Aquaculture wastewater treatment through microalgal: biomass potential applications on animal feed, agriculture, and energy
Publication . Viegas, Catarina; Gouveia, Luisa; Gonçalves, Maria Margarida
ABSTRACT: The use of microalgae to remediate raw effluent from brown crab aquaculture was evaluated by performing batch mode growth tests using separately the microalgae Chlorella vulgaris (Cv), Scenedesmus obliquus (Sc), Isochrysis galbana (Ig), Nannocloropsis salina (Ns), and Spirulina major (Sp). Removal efficiencies in batch growth were 100% for total nitrogen and total phosphorus for all microalgae. Chemical oxygen demand (COD) remediations were all above 72%. Biomass productivity varied from 20.9 mg L-1 day- 1 (N. salina) to 146.4 mg L-1 day- 1 (C. vulgaris). The two best performing algae were C. vulgaris and S. obliquus and they were tested in semicontinuous growth, reaching productivities of 879.8 mg L-1 day- 1 and 811.7 mg L-1 day- 1, respectively. The bioremediation of the effluent was tested with a transfer system consisting of three independent containers and compared with the use of a single container. The single container had the same capacity and received weekly the same volume of effluent as the three containers together. The remediation capacity of the 3 containers was much higher than the single one. The supplementation with NaNO3 was tested to improve the nutrient removal microalgae? capacity, with positive results. The removal efficiencies were 100% for total nitrogen and total phosphorus and higher than 96% for COD. The obtained C. vulgaris and S. obliquus biomass were composed of 31 and 35% proteins, 6 and 8% lipids, 39 and 30% carbohydrates, respectively. The composition of these biomass suggest that it can be used as novel and sustainable ingredients in aquaculture feeds. The algal biomass of Cv and Sc were used as biostimulants in the germination of wheat and watercress, and very promising results were attained, with increases in the germination index for Cv and Sc of 175% and 48% in watercress and 84% and 98% in wheat, respectively. The biomasses of Cv and Sc were also subjected to a torrefaction process with 72.5 ? 1.7% char yields. The obtained biochars were tested as biostimulants for germination seeds (wheat and watercress) and as bio-adsorbent of dye solutions.
Bioremediation of cattle manure using microalgae after pre-treatment with biomass ash
Publication . Viegas, Catarina; Gouveia, Luisa; Margarida Gonçalves, Maria
ABSTRACT: In this work, cattle manure was diluted and pre-treated with biomass ash to yield a liquid fraction and a solid precipitate. Microalgae grown in the liquid fraction, in batch and semi-continuous mode, achieved maximum biomass productivities of 522.9 and 554.3 mg L−1 day−1 (12 days) for Chlorella protothecoides and Tetradesmus obliquus, respectively. Nutrient removal efficiency was highest for the semicontinuous mode with replacement of 10% of reactor volume every 48 h. The produced algal biomass was characterized for its nutrient composition. Both, algal biomass, and precipitate aqueous extracts, were evaluated as biostimulants for wheat and watercress seeds Increments in the germination index were 177% for wheat with Chlorella protothecoides and 34% for watercress with Tetradesmus obliquus. The strategy adopted in this work is coherent with circular economy principles, combining effluent treatment with the production of added-value materials that could be used as biostimulants or animal feed additives.
Low indirect land use change (ILUC) energy crops to bioenergy and biofuels: a review
Publication . Abreu, Mariana; Silva, Luís; Ribeiro, Belina; Ferreira, Alice; Alves, Luís; Paixão, Susana M.; Gouveia, Luisa; Moura, Patrícia; Carvalheiro, Florbela; Duarte, Luís C.; Fernando, Ana Luisa; Reis, Alberto; Gírio, Francisco
ABSTRACT: Energy crops are dedicated cultures directed for biofuels, electricity, and heat production. Due to their tolerance to contaminated lands, they can alleviate and remediate land pollution by the disposal of toxic elements and polymetallic agents. Moreover, these crops are suitable to be exploited in marginal soils (e.g., saline), and, therefore, the risk of land-use conflicts due to competition for food, feed, and fuel is reduced, contributing positively to economic growth, and bringing additional revenue to landowners. Therefore, further study and investment in R&D is required to link energy crops to the implementation of biorefineries. The main objective of this study is to present a review of the potential of selected energy crops for bioenergy and biofuels production, when cultivated in marginal/degraded/contaminated (MDC) soils (not competing with agriculture), contributing to avoiding Indirect Land Use Change (ILUC) burdens. The selected energy crops are Cynara cardunculus, Arundo donax, Cannabis sativa, Helianthus tuberosus, Linum usitatissimum, Miscanthus × giganteus, Sorghum bicolor, Panicum virgatum, Acacia dealbata, Pinus pinaster, Paulownia tomentosa, Populus alba, Populus nigra, Salix viminalis, and microalgae cultures. This article is useful for researchers or entrepreneurs who want to know what kind of crops can produce which biofuels in MDC soils
Evaluation of the potential of biomass to energy in Portugal : conclusions from the CONVERTE project
Publication . Abreu, Mariana; Reis, Alberto; Moura, Patrícia; Fernando, Ana Luisa; Luís, Gabriel; Quental, Lídia; Patinha, Pedro; Gírio, Francisco
ABSTRACT: The main objective of the Portuguese project "CONVERTE-Biomass Potential for Energy" is to support the transition to a low-carbon economy, identifying biomass typologies in mainland Portugal, namely agri-forest waste, energy crops and microalgae. Therefore, the aim was to design and construct a georeferenced (mapping) database for mainland Portugal, to identify land availability for the implementation of energy crops and microalgae cultures, and to locate agricultural and forestry production areas (including their residues) with potential for sustainable exploitation for energy. The ArcGIS software was used as a Geographic Information System (GIS) tool, introducing the data corresponding to the type of soil, water needs and edaphoclimatic conditions in shapefile and raster data type, to assess the areas for the implantation of the biomass of interest. After analysing the data of interest in each map in ArcGIS, the intersection of all maps is presented, suggesting adequate areas and predicting biomass productions for the implementation of each culture in mainland Portugal. Under the conditions of the study, cardoon (72 kha, 1085 kt), paulownia (81 kha, 26 kt) and microalgae (29 kha, 1616 kt) presented the greater viability to be exploited as biomass to energy in degraded and marginal soils.
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Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
6817 - DCRRNI ID
Funding Award Number
UIDP/04077/2020