Thermal plasma technology for the treatment of wastes: a critical review

Our plain-English summary of Thermal plasma technology for the treatment of wastes: a critical review, by E. Gomez, D.A. Rani, C.R. Cheeseman, et al (Journal of Hazardous Materials, 2009).

The study

• Authors: E. Gomez, D.A. Rani, C.R. Cheeseman, D. Deegan, M. Wise, A.R. Boccaccini
• Journal: Journal of Hazardous Materials
• Published: 2009;161(2-3):614-26
• Type of article: Review
• Cited by: 96 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This review describes the current status of waste treatment using thermal plasma technology. A comprehensive analysis of the available scientific and technical literature on waste plasma treatment is presented, including the treatment of a variety of hazardous wastes, such as residues from municipal solid waste incineration, slag and dust from steel production, asbestos-containing wastes, health care wastes and organic liquid wastes. The principles of thermal plasma generation and the technologies available are outlined, together with potential applications for plasma vitrified products. There have been continued advances in the application of plasma technology for waste treatment, and this is now a viable alternative to other potential treatment/disposal options. Regulatory, economic and socio-political drivers are promoting adoption of advanced thermal conversion techniques such as thermal plasma technology and these are expected to become increasingly commercially viable in the future.

In plain English

This article was a review, not a new study. The authors, from Imperial College London and the UK company Tetronics Ltd., surveyed published scientific and technical reports on using thermal plasma to treat hazardous wastes. Thermal plasma is an electrically generated gas heated to very high temperatures. The wastes covered included incinerator ash and air pollution control residues, steelmaking dust and slag, healthcare wastes, and asbestos-containing wastes. No people were studied and no health outcomes were measured. In its asbestos section, the review described earlier experiments in which several kinds of asbestos were melted in an experimental argon plasma facility. Those reports gave volume and weight reductions of 51% and 70%, which the reviewers said suggested only a partial treatment. The review also described a commercial plasma facility in France (INERTAM) and UK work by Tetronics Limited, where an independent government laboratory detected no asbestos fibres in the final product, the reactor or the downstream duct work. The authors concluded that plasma was a promising alternative to conventional thermal processes, but that it was not clear that large-scale plasma treatment of wastes was economically viable.

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: Review of published scientific and technical literature on thermal plasma treatment of hazardous wastes
• Who was studied: No human population. The review covered published reports on many types of waste treated by plasma, including municipal incinerator ash and residues, asbestos-containing wastes, healthcare wastes, steelmaking wastes, electroplating sludge, aluminium dross, carbon- and chlorine-containing wastes.
• Exposure: Not a health exposure study. Among the wastes reviewed were asbestos-containing wastes treated by plasma melting in experimental and commercial facilities.
• Main results:
  • In earlier experiments the review cited, plasma treatment of asbestos gave a volume reduction of 51% and a weight reduction of 70%. The reviewers attributed this to removal of water from the wet removal process and said it suggested only a partial treatment.
  • The same cited experiments reported that asbestos could be converted into a rocklike structure (hardness of 6 Mohs) by reducing sample thickness and melting.
  • The review described a commercial facility in France (INERTAM) that treats asbestos waste by high-temperature plasma vitrification, using air as the plasma gas, to give a product described as inert, non-leachable and fibre-free.
  • In UK work by Tetronics Limited cited in the review (a conference paper whose authors include two of this review's authors), a transferred arc plasma furnace converted asbestos-containing materials into a gehlenite-akermanite monolith. An independent government laboratory detected no asbestos fibres in the final wasteform, the reactor or the downstream duct work.
• The authors' conclusion: The authors concluded that technical feasibility had been shown for several hazardous wastes but that it was not clear large-scale plasma treatment was economically viable. They also concluded that thermal plasma was a promising alternative to conventional thermal processes.
• Limitations the authors state:
  • The authors stated that few cost estimates for plasma arc treatment exist and that such early-stage estimates tend to be highly inaccurate.
  • The authors stated that the main disadvantage of the plasma process is its use of electricity, an expensive energy source.

Related studies

• Mechanochemical treatment to recycling asbestos-containing waste — P. Plescia, D. Gizzi, et al. (2003)
• Microwave thermal inertisation of asbestos containing waste and its recycling in traditional ceramics — C. Leonelli, P. Veronesi, et al. (2006)
• Neutralization of cement-asbestos waste by melting in an arc-resistance furnace — J. Witek, R. Kusiorowski (2017)
• The Self-sustained High temperature Synthesis (SHS) technology as novel approach in the management of asbestos waste — L. Gaggero, M. Ferretti (2018)
• A study of silicon carbide synthesis from waste serpentine — T.W. Cheng, C.W. Hsu (2006)
• A review of mechanochemistry applications in waste management — X. Guo, D. Xiang, et al. (2010)

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