Browsing by Author "Viegas, Catarina"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- A circular approach for landfill leachate treatment: Chemical precipitation with biomass ash followed by bioremediation through microalgaePublication . Viegas, Catarina; Nobre, Catarina; Mota, Andre; Vilarinho, Candida; Gouveia, Luisa; Goncalves, MargaridaThe 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 energyPublication . Viegas, Catarina; Gouveia, Luisa; Goncalves, MargaridaThe 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.
- Evaluation of microalgae as bioremediation agent for poultry effluent and biostimulant for germinationPublication . Viegas, Catarina; Gouveia, Luisa; Gonçalves, MargaridaThis work addresses how a pre-treatment involving biomass ash influences the poultry effluent’s bioremediation using three microalga strains, such as Chlorella vulgaris, Chlorella protothecoides and Tetradesmus obliquus. The undiluted effluent served as the culture medium for the growth, both in batch and semi continuous modes, and the remediation efficiency and biomass production yield were quantified. The combination strategy in batch mode, allowed removal efficiency of 100% for total nitrogen, more than 80% for total phosphorus and over 70% for chemical oxygen demand. Average biomass productivities for 10 days of 94.9, 76.2 and 72.0 mg L−1 day−1 were obtained for T. obliquus, C. vulgaris and C. protothecoides, respectively. Regarding semi-continuous strategy (28 days), the biomass productivities achieved were 245 and 194 mg L−1 day−1 for T. obliquus and C. vulgaris, respectively. Remediation rates of 100% for total nitrogen and phosphorus, and over 92% for COD were attained. The microalga composition was assessed for protein, sugar, lipid, and ash contents. The produced biomasses were tested as biostimulant and showed a 147% increase in wheat germination index, for the C. vulgaris microalga. The use of the precipitate from the biomass ash pre-treatment as fertilizer in germination tests was also assessed and results in an increase of 26%, for 10% of precipitate incorporation.
- A produção oleira romana no AlgarvePublication . Bernardes, João Pedro; Viegas, CatarinaA produção oleira romana no Algarve encontra-se repartida por toda a região, ainda que se fixe no litoral e, na maior parte dos casos, em relação directa com os centros produtores de preparados piscícolas. Conhece-se cerca de uma dúzia de centros oleiros que produziram ânforas, cerâmica doméstica e de construção. A maior parte destes centros oleiros surgem a partir do século III, dedicando-se principalmente à produção de contentores para transporte de preparados de peixe, ainda que, nas olarias do Algarve oriental de S. Bartolomeu de Castro Marim e da Manta Rota, tenha ocorrido ainda no Alto Império. A produção tardia local deste tipo de recipientes tem sido relacionada com diversos factores, sendo sugerido que a região recorreu durante os primeiros séculos da nossa Era a ânforas oriundas da vizinha Bética para envasar os seus produtos piscícolas. Só a partir de então, como reacção ao incremento da exploração local dos recursos marinhos e ao declínio das olarias da Bética, é que os centros oleiros algarvios se afirmarão.Depois de se abordarem os tipos anfóricos produzidos na região bem como a distribuição dos respectivos centros oleiros, focam-se as estruturas de produção, nomeadamente a organização da olaria do Martinhal, a maior do Algarve,que produziu ânforas, cerâmica comum e cerâmica de construção até época tardia.
- Roman amphora production in the Algarve (Southern Portugal)Publication . Bernardes, João Pedro; Viegas, CatarinaDuring the Roman period, pottery production was disseminated across the Algarve region, mainly on the coast, and in most cases it has a direct connection with fish-salting units. Somewhat fewer than ten production sites are known to have manufactured amphorae and complementarily domestic pottery and building ceramics, although on only five of them have the fabrics been studied and published. The site at Martinhal on the westernmost part of the coast deserves to be specially highlighted, since it is the only one where the dimensions of the production area are better known, and there are features that allow the evaluation of the structures that supported the production. Most of these production centres began in the 3rd century AD and were dedicated mostly to the manufacture of amphorae to contain and transport fish products, such as types Almagro 50, Almagro 51c and Almagro 51a-b/Algarve 1. Local production prior to the 3rd century was rare, and the only workshops known were located in the eastern Algarve, in S. Bartolomeu de Castro Marim and in Manta Rota, where a late variant of type Dressel 14 was produced. The increase in fish salting from the 3rd century onward certainly contributed to the affirmation of the pottery production units in the region.