Browsing by Author "Ribeiro, A. B."
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- Heavy metals in MSW incineration fly ashesPublication . Ferreira, Célia; Ribeiro, A. B.; Ottosen, Lisbeth M.Incineration is a common solution for dealing with the increasing amount of municipal solid waste (MSW). During the process, the heavy metals initially present in the waste go through several transformations, ending up in combustion products, such as fly ash. This article deals with some issues related to the combustion of MSW and the formation of fly ash, especially in what concerns heavy metals. Treatment of the flue gas in air pollution control equipment plays an important role and the basic processes to accomplis this are explained. Fly ash from a semi-dry flue gas treatment system is characterized regarding its physical-chemical properties : pH, solubility, chemical composition, and leaching, amongst others. Results indicate a high alkalinity and the presence oflarge amounts of calcium, chlorides, sulfates, carbonates, sodium and potassium. Metal concentrations in fly ash are : 6, 2 g/kg for zinc, 2, 4 g/kg for lead, 1, 7 gzkg fior iron, and 7, 9 g/kg for magnesium. Copper, manganese, chromium and cadmium are also present with 546, 338, 104 and 91 mg/kg ofBy ash, respectively. These results are extremely important in subsequent studies on the treatment of fly ash.
- A new approach to soil remediation: coupling nanotechnology with electrically induced particle transport (Electrokinetics)Publication . Gomes, H.; Ferreira, Célia; Ribeiro, A. B.; Loch, G.; Ottosen, Lisbeth M.Traditional remediation technologies for Persistent Organic Pollutants (POP) such as Polychlorinated Biphenyls (PCBs) have serious limitations and high costs. Zero valent iron nanoparticles (nZVI) represent a new generation of environmental remediation technologies that could provide cost-effective solutions. However, the limited transport of nZVI through soils has been identified to be a major drawback for in situ applications. The main research objective of this study is to find out if coupling electrokinetics and reactive iron nanoparticles can be an effective method for treating PCBs contaminated soils, through electrically induced nanoparticle transport. To understand the fundamental aspects of the coupled technology the authors suggest dividing the overall problem into three submodels (transport of nanoparticles by electroosmosis and by electrophoresis and degradation of PCB) which are then integrated into a macroscale transport/degradation numerical model. This paper presents the experimental approach suggested for each submodel under study. Testing this innovative solution using the suggested approach will allow for a deeper understanding of both the electrokinetically enhanced transport of nZVI and PCBs dechlorination.
- Possible applications for municipal solid waste fly ashPublication . Ferreira, Célia; Ribeiro, A. B.; Ottosen, Lisbeth M.The present study focuses on existing practices related to the reuse of Municipal Solid Waste (MSW) fly ash and identifies new potential uses. Nine possible applications were identified and grouped into four main categories: construction materials (cement, concrete, ceramics, glass and glass–ceramics); geotechnical applications (road pavement, embankments); “agriculture” (soil amendment); and, miscellaneous (sorbent, sludge conditioning). Each application is analysed in detail, including final-product technical characteristics, with a special emphasis on environmental impacts. A comparative analysis of the different options is performed, stressing the advantages but also the weaknesses of each option. This information is systemized in order to provide a framework for the selection of best technology and final products. The results presented here show new possibilities for this waste reuse in a short-term, in a wide range of fields, resulting in great advantages in waste minimization as well as resources conservation.