1,720,987 research outputs found
The Critical Raw Materials Potential of Anthropogenic Deposits: Insights from Solid Residues of Municipal Waste Incineration
No full textDue to the current and foreseen global growth of raw material demand, the sustainable supply of minerals and metals for high-tech applications, the so-called critical raw materials (Co, Cr, Ga, Nb, Rare Earth Elements, Sb, W, Platinum Group Elements), is of general concern. Industrial wastes have the potential to become an alternative source (flow) of strategic metals and, consequently, their valorisation can be seen as a move towards resources efficiency and circular economy.
In this 3-years study I aimed to decipher the critical raw materials potential from solid residues produced by Municipal Solid Waste Incineration (MSWI), namely bottom and fly ashes. These solid residues, coming from different leading companies of MSWI in northern Italy, have been selected because they can be accounted for urban mining purposes and represent high elements flows, still poorly explored. In the present work I address the potential of MSWI solid residues as an alternative source of critical raw materials by studying the material chemistry, its resources flow and the evaluation of metals upgrading and recovery. Finally, I tackle some environmental and economic issues
The potential impact of municipal solid waste incinerators ashes on the anthropogenic osmium budget
No full textOsmium release from Municipal Solid Waste Incinerators (MSWI), even if acknowledged to occur at least over the last fifteen years, remains overlooked in the majority of recent studies. We present the osmium concentration and (187)Os/(188)Os isotopic measurements of different kinds of bottom and fly ash samples from MSWI plants and reference materials of incinerator fly ash (BCR176 and BCR176R). The analysis of the unknown ash samples shows a relatively wide range of (187)Os/(188)Os ratios (0.24-0.70) and Os concentrations (from 0.026ng/g to 1.65ng/g). Osmium concentrations and isotopic signatures differ from those of other known Os sources, either natural or manmade, suggesting a mixture of both contributions in the MSWI feedstock material. Furthermore, the comparison between the BCR176 and the renewed BCR176R indicates a decrease in Os concentration of one order of magnitude over the years (from 1 to 0.1ng/g) due to improved recycling efficiency of Os-bearing waste. The estimated annual amount of Os from a typical incinerator (using average Os values and MSWI mass balance) is 13.4g/a. The osmium potentially released from MSWI smokestacks is predicted to be from 16 to 38ng Os/m(2)/a, considering a medium size country having 50 MSWI facilities; therefore much higher than the naturally transported osmium from continental dust in the atmosphere (about 1pg Os/m(2)/a). MSWI systems are considered one of the best options for municipal solid waste management in industrialised countries, but their contribution to the Os budget can be significant
Sediment quality of the Ridracoli fresh water reservoir in Italy: Insights from aqua regia digestion and sequential extractions
No full textThe inter-element relationships and the forms in which metals exist strongly influence their mobility and, in turn, have a signature on the environment and human health. Located in the northern Apennines within the Emilia-Romagna re-gion, the Ridracoli artificial lake is one of Italy's most important reservoirs that provides drinking water for about one million people. This work characterized the reservoir sediments by ICP-MS after aqua regia digestion (ARD), compar-ing the limits by law to assess environmental compliance and XRF data from the same sample-set taken as total con-centrations. The Degree of Extraction (DE) from pseudo-total concentrations of ARD analysis allows assessing elements mobility and the associated environmental risk. Principal Component Analysis (PCA) on the obtained data helped to investigate inter-element relationships better; for example, we observed carbonate-sourced sediments, many trace elements (e.g., Ni, Zn) linked to FeMn oxyhydroxides, the importance of the grain size in elements distri-bution, and the central role of the organic matter in element partitioning. In addition, a Sequential Extraction Proce-dure (SEP) was applied to the sediment samples to understand the partitioning of many analytes, including Potentially Harmful Elements (PHE) such as Fe, Mn, Cu, Cr, Ni, Pb, and Zn. The results indicated that the most easily mobilized forms were predominant in the area near the dam, in correspondence to sediments affected by the formation of a seasonal anoxic layer
The rare earth elements in municipal solid waste incinerators ash and promising tools for their prospecting
Full text linkBottom and fly ashes from Municipal Solid Waste Incinerators (MSWI) are hazardous products that present concern for their safe management. An attractive option to reduce their impact both on the environment and the financial commitment is turning MSWI ashes into secondary raw materials. In this study we present the REE content and distribution of bottom and fly ashes from MSWI after a highly effective digestion method and samples analysis by ICP-MS. The chondrite-normalised REE patterns of MSWI bottom and fly ash are comparable with that of crustal averages, suggesting a main geogenic source. Deviations from typical crustal pattern (e.g., Eu, Tb) disclose a contribution of likely anthropogenic provenance. The correlation with major elements indicates possible sources for REE and facilitates a preliminary resource assessment. Moreover, magnetic susceptibility measurements can be a useful prospecting method in urban ores made of MSWI ashes. The relationship between REE and some influencing parameters (e.g., Pricing Influence Factor) emphasises the importance of MSWI ash as alternative source of REE and the need of further efforts for REE recovery and purification from low concentrations but high flows waste
Metal recovery from municipal solid waste incinerators fly ash by sulphuric acid leaching and bioleaching
No full textMunicipal solid waste incinerators (MSWI) ashes are being investigated in order to understand recovery opportunities with the final aim of diversifying sourcing and partly overcoming raw materials shortage. Turning waste into resource in the most efficient way is challenging, especially when secondary critical raw materials are the final objectives of recovery. The advances on bio- and hydrometallurgy are crucial for enhanced metals recovery and mitigation of environmental risks directly associated with the treatment of solid waste.
Here we present preliminary results of bio- and hydrometallurgical experiments for critical metals recovery from MSWI fly ash and a comparison of the performance characteristics between acid leaching and acid bioleaching. Sulphuric acid leaching showed the advantage of reduction and mobilisation of Ca, thus improving the quality of the final product. Conversely, bioleaching experiments were performed in a mixed culture of T. ferrooxidans and T. thiooxidans and their efficiency was evaluated over a period of several weeks; reagents involved are lower than those needed for acid leaching thus making the process economically feasible and more environmental friendly. The influence of the experimental parameters will be discussed for both acid leaching and acid bioleaching procedures
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Grain size and mineralogical constraints on leaching in the bottom ashes from municipal solid waste incineration: a comparison of five plants in northern Italy
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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