From hazardous asbestos containing wastes (ACW) to new secondary raw material through a new sustainable inertization process: A multimethodological mineralogical study

Our plain-English summary of From hazardous asbestos containing wastes (ACW) to new secondary raw material through a new sustainable inertization process: A multimethodological mineralogical study, by N.M. Marian, G. Giorgetti, C. Magrini, et al (Journal of Hazardous Materials, 2021).

The study

• Authors: N.M. Marian, G. Giorgetti, C. Magrini, G.C. Capitani, L. Galimberti, A. Cavallo, R. Salvini, C. Vanneschi, C. Viti
• Journal: Journal of Hazardous Materials
• Published: 2021;413:125419
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Nowadays, asbestos-containing wastes (ACW) still represent an important environmental problem and a severe health hazard due to the well known pulmonary diseases derived from asbestos fibers inhalation. Except for a very few cases, ACW are currently confined in controlled landfills, giving rise to increasingly high amounts of still hazardous wastes. A promising alternative to landfill confinement is represented by ACW inertization, but the high cost of the inertization processes so far proposed by the scientific community have hampered the creation of actually operative plants. In this paper, we explore the possibility to use an innovative process that ensures the obtainment of asbestos-free inert material in an exceptionally short processing time, thus greatly reducing cost-related problems. The efficacy of the inertization process has been verified through accurate mineralogical investigations on both chrysotile and crocidolite de-activated fibers, through X-ray diffraction, scanning and transmission electron microscopy. Overall mineralogical, microstructural and granulometric characteristics of the inert bulk material suggest that it could be successfully re-used as a secondary raw material in ceramic industries. This innovative inertization procedure could therefore provide an effective and economically sustainable solution for ACW management.

Copyright © 2021 Elsevier B.V. All rights reserved.

In plain English

This study tested a patented heat treatment to destroy asbestos in waste fiber-cement roofing panels. The authors first examined panels from 26 industrial and civil buildings in Tuscany, Italy. Of these, 39% contained chrysotile and crocidolite, 27% chrysotile alone, 19% chrysotile plus man-made vitreous fibers, and 4 (15%) no asbestos. Four panels with both fiber types were heated at an industrial pilot plant to 1100 degrees C for about 15 minutes. These were then analyzed in the laboratory by X-ray and electron microscopy methods. The treated material was mostly glassy, about 55 to 78% by weight. Chrysotile was replaced by olivine and pyroxene nanocrystals 10 to 150 nanometers in size. Crocidolite was replaced by olivine, pyroxenes and glassy material. Both became brittle. Decomposed chrysotile fell apart very easily, but decomposed crocidolite was tough and harder to extract. The authors concluded that all asbestos fibers were irreversibly eliminated and the product could be reused as raw material. They called the safety of the resulting nanoparticles a legitimate concern, with cell tests planned. The study did not measure health effects in people.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Mineralogical study of asbestos-cement waste before and after a patented short thermal inertization (heat treatment). The treatment was carried out at an industrial pilot plant, and the materials were then analyzed with laboratory techniques.
• Who was studied: Fiber-cement roofing panels from 26 industrial and civil buildings in Tuscany, Italy, supplied by two asbestos-removal companies. Four panels (TEC1 to TEC4) were selected for the inertization tests at the Scame Forni Industriali pilot plant in Treviso, Italy.
• Exposure: Eternit-like asbestos-cement panels containing chrysotile and crocidolite, heated to 1100 degrees C for about 15 minutes without prior grinding
• Main results:
  • Of the 26 panels examined, 39% contained both chrysotile and crocidolite, 27% chrysotile alone, and 19% chrysotile plus man-made vitreous fibers. 4 panels (15%) were asbestos-free and contained only man-made vitreous fibers.
  • In the four treated panels, amorphous (glassy) material was the dominant phase, ranging from about 55 to 78% by weight. The calcium silicate larnite ranged from about 15 to 31% by weight.
  • In the treated panels, chrysotile was replaced by olivine and pyroxene nanocrystals 10 to 150 nm in size, held in amorphous material. The original fibrous outline was kept as a pseudomorph.
  • In the treated panels, crocidolite was replaced by fayalitic olivine, pyroxenes and silica-rich amorphous material.
  • Both decomposed fiber types were brittle. Decomposed chrysotile disaggregated very easily, whereas decomposed crocidolite was tough and more difficult to extract from the bulk material.
• The authors' conclusion: The authors concluded that their investigations demonstrated the effectiveness of the inertization process and the irreversible disappearance of all asbestos fibers. They also concluded that the treated waste appears promising for recycling as a secondary raw material.
• Limitations the authors state:
  • The treatment produces particles partly in the nanoparticle range. The authors said the safety of these nanomaterials for human health is a legitimate concern, and that in vitro experiments on biological effects are only planned.
  • A detailed economic analysis (cost-benefit and Life Cycle Assessment) had not been completed and was to be presented elsewhere.

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Crocidolite, X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM).

Related studies

• Dark fermentation process as pretreatment for a sustainable denaturation of asbestos containing wastes — D. Spasiano (2018)
• Development of a testing method for asbestos fibers in treated materials of asbestos containing wastes by transmission electron microscopy — T. Yamamoto, A. Kida, et al. (2014)
• Sustainable bio-hydrothermal sequencing treatment for asbestos-cement wastes — D. Spasiano, V. Luongo, et al. (2019)
• Leaching behaviour of hazardous demolition waste — N. Roussat, J. Méhu, et al. (2008)
• Health effects of hazardous waste — S.M. Dearwent, M.M. Mumtaz, et al. (2006)
• Human exposure to trace elements and PCDD/Fs around a hazardous waste landfill in Catalonia (Spain) — M. Herrero, J. Rovira, et al. (2020)

Browse more research in Journal of Hazardous Materials, or return to medical research.