Process optimization of the removal of mercury, cobalt and nickel in mixture by the living macroalgae Ulva lactuca

• Autor(a) principal: Morais, Tiago Fernando Teixeira
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/31957
• topic: Sorption; Biomarkers; Potentially toxic elements; Water; Surface response methodology; Biotechnology

Factors such as populational and economic growth, and climate changes have consequences and are threats to aquatic systems, leading to water contamination, that contributes to its scarce as a resource. This work aimed to study the capacity of the living macroalgae Ulva lactuca to act as a biosorbent in the removal of mercury, cobalt and nickel from real saline water. A first toxicity evaluation study showed that these three elements cause biochemical changes in mussel Mytilus galloprovincialis, being responsible for activating antioxidant defenses, reducing metabolic activity, and spending energy reserves. These results reinforce the importance of developing efficient and sustainable techniques to remove these contaminants from water. In the trials performed, the macroalgae under study showed promising results int the removal of the three elements, presenting at the end of exposure (120 h) removals in the range of 65 – 98 % for mercury, 83 – 97 % for cobalt and 78 – 95 % for nickel, being that these ranges of removal percentages include different initial conditions. Through the surface response methodology, combined with the experimental design of Box-behnken, the operational conditions were optimized in terms of initial macroalgae dosage, water salinity, and initial concentration of elements. In terms of time, it was concluded that, to the tested conditions, the extension of the process from 48 to 120 h does not present relevant advantages in terms of efficiency. Globally, this work provides an important complement to the literature in terms of removed contaminants, used matrices and mixture studied.