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Application of the electrodialytic process for tungsten recovery and arsenic removal from mine tailings
Publication . Rosário, Ana Rita Adrião; Almeida, Joana; Ribeiro, Alexandra
Mining tailings (MT) deposited in open dams can cause environmental problems. On the other hand, these residues can be seen as a secondary source of critical raw materials. The present dissertation is the first attempt to study the efficiency of the application of the electrodialytic process (ED) for tungsten (W) recovery and arsenic (As) removal from Panasqueria mine residues (Covilhã, Portugal).
Nine experiments were performed, some in duplicate, using cells with two (2C) and three (3C) compartments, in the presence of cation (CAT) and anion (AN) exchange membranes, with current intensities between 0 and 100 mA and durations between 7 and 14 days. The MT sample was placed in the central cell compartment in the 3C setup and directly in the anode or cathode compartment in a 2C cell.
The results show that the 2C cell setup with an AN presented the highest W recovery (0.15 %) and As removal (23.51 ± 21.33 %). When a CAT was applied to the same cell configuration, W and As migration from the sample to the electrolyte compartment was not verified, and no elements recovery or removal occurred. Further preliminary tests were carried out adding three adjuvants to the sample. The 2C cell setup with a CAT was applied since the 2C AN cell showed to be instable. When the adjuvant B was added, the recovery of W achieved 0.64 % and the removal of As 9.48 %.
The higher the current intensity applied the better the W recovery and the As removal obtained. However, W recovery was lower than the As due to the presence of sulfates in the sample that promote the formation of W complexes. Future experimental work should be carried out to optimize the ED conditions, not obtained in the present dissertation.
Overview of electronic tongue sensing in environmental aqueous matrices: Potential for monitoring emerging organic contaminants
Publication . Magro, Cátia; Mateus, Eduardo P.; Raposo, Maria; Ribeiro, Alexandra B.; CENSE - Centro de Investigação em Ambiente e Sustentabilidade; DCEA - Departamento de Ciências e Engenharia do Ambiente; DF – Departamento de Física; CeFITec – Centro de Física e Investigação Tecnológica; National Research Council of Canada
Emerging organic contaminants (EOC) are synthetic or naturally occurring chemicals that have the potential to enter the environment and cause known or suspected adverse ecological and human health effects. Despite not being commonly monitored, EOC are often detected in effluents and water bodies because of their inefficient removal in conventional wastewater treatment plants. There is a growing concern about the presence and impact of EOC as well as the need for reliable and effective water monitoring using sensors capable of detecting the target molecules in complex media. Due to their specificities, such as fast response times, low cost, portability and user-friendly operation, electronic tongue (e-tongue) systems present some advantages over the traditional analytical techniques (e.g., chromatographic systems) used for environmental monitoring. We reviewed e-tongue sensors, focusing on their ability for real-time environmental monitoring. A bibliometric evaluation was carried out, along with a study of the status of the existing e-tongue systems, how they worked, and their applications in different fields. The potential of e-tongue sensors to detect organic contaminants in aqueous environmental matrices is discussed, with a particular focus on EOC.
Why, how and what do organizations achieve with the implementation of environmental management systems? Lessons from a comprehensive review on the Eco-Management and Audit Scheme
Publication . Tourais, Patrícia; Videira, Nuno; CENSE - Centro de Investigação em Ambiente e Sustentabilidade; DCEA - Departamento de Ciências e Engenharia do Ambiente; Molecular Diversity Preservation International (MDPI)
The Eco-Management and Audit Scheme (EMAS) was established in 1993 in the European Union as a voluntary instrument facilitating the implementation of organisational environmental policies and management of environmental aspects. We present a comprehensive literature review on EMAS research, organized according to three broad questions: Why do organisations choose EMAS? How is the scheme implemented and adapted to organisational characteristics? And what results are achieved? We have built analysis matrices to critically review 80 articles published over the past two decades and to identify the recurrent research themes addressing each question. We found that the decision to adopt EMAS is motivated by a set of internal and external factors, compounded by the potential of an organisation to combine the scheme with other EMS standards and environmental management tools. These themes are the ones most extensively covered by existing literature. To answer the question on how organisations implement and adapt to the scheme, two themes have been identified covering EMS planning and operation issues and sectoral approaches. Results show that the focus has been put on development of methods for assessing the significance of environmental aspects, implementing environmental policies and developing indicators for tracking performance and elaborating environmental statements. The development of sectoral approaches that adapt EMAS to characteristics of different economic activity sectors is also emerging as a critical research development. Finally, the themes addressing results achieved with EMAS implementation have only recently surfaced in the literature. The achievement of sustained environmental performance improvements through EMAS adoption is both contested and supported in the reviewed studies. On the other hand, improvements in the relationships with stakeholders arise as one of the most important intangible outcomes of the scheme. We conclude our review by advancing a systematic set of future research opportunities in this field.
Sustainability of construction materials: Electrodialytic technology as a tool for mortars production
Publication . Magro, C.; Paz-garcia, J. M.; Ottosen, L. M.; Mateus, E. P.; Ribeiro, A. B.; DCEA - Departamento de Ciências e Engenharia do Ambiente; CENSE - Centro de Investigação em Ambiente e Sustentabilidade; Elsevier
The reduction of tap water consumption in all activity sectors, including the building industry, is crucial to the sustainability of water resources. Effluents from wastewater treatment plants have the potential to replace freshwater in the construction sector but they contain a critical mixture of impurities, which hampers their use in mortars production. In this work, the viability of using effluent as an alternative to potable water for the production of mortars, after electrodialytic treatment, was assessed. Electrodialytic technology (ED-T) is a proven technique for decontamination of porous and aqueous matrices. ED-T experiments were conducted with 500 mL of effluent for 6, 12 and 24 h, with a current intensity of 25 mA. The results showed that after ED-T 6 h, the removal efficiencies of critical components were above 85% of their initial concentrations. Mortar properties such as setting time, workability, flexural strength, compressive strength and morphology were obtained for 100% effluent and tap water/effluent mixtures (50:50) with and without ED-T pre-treatment. The mortars with the ED-T treated effluent showed similar initial setting times and workability, higher flexural and compressive strength compared to the mortars reference.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
5876
Número da atribuição
UID/AMB/04085/2013