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Slag Quality and Air Emissions from Plasma Arc Gasification of MSW
Project Description:
Plasma technology has been proposed for municipal solid waste (MSW) treatment in several municipalities in Florida.
Although a limited number of small-scale projects utilize plasma technology for MSW and other wastes in different parts of the
world, this technology has not been used at the large scale being proposed in Florida. In this treatment process, MSW is heated
to a very high temperature using a plasma arc in an oxygen-free or oxygen-starved environment producing syngas
(used for electricity production) and a molten slag which, upon cooling, converts to a vitreous material. Promoters of this technology
claim that this vitreous slag is less likely to leach contaminants and thus may be beneficially used as a construction aggregate
(and not require landfilling). Limited leaching data available concerning Toxicity Characteristic Leaching Procedure (TCLP) testing
on this material show that while leaching is reduced, some elements (e.g., As, Cd, Pb, Cr and Zn) may leach above groundwater
risk thresholds (FDEP, 2007; Lin and Chang, 2006). While helping the formation of vitreous slag, the high temperature plasma arc also
enhances vaporization of metals which later on condense to form ultrafine metal aerosol and exhaust as particulate matter (PM) emission.
Additional data is needed on the emissions and risks associated with solid and gaseous products of this technology.
This research proposes to meet the following specific objectives:
(1) Using a bench-scale plasma arc gasification system designed under
a previous Hinkley Center project, create a suite of vitreous slag material using a plasma arc torch,
(2) Characterize the leaching potential of contaminant chemicals from the vitrified slag samples,
(3) Characterize the air emissions associated with the plasma treatment of the aforementioned wastes, and
(4) Assess the potential for plasma arc slag to be beneficially reused in Florida. Report:
Status: A laboratory-scale plasma system for thermal treatment of solid waste
is currently being developed and installed at the Polk County North Central Landfill with funding from the Hinkley Center.
The system consists of a plasma torch assembly and a furnace with a water-cooled housing, two sample feeding units,
a unit to deliver vitrified material from the furnace, and a gas sample port. Vitrified materials and gas exhaust will be collected and
characterized from different experimental runs on different materials.
Investigators:
Timothy Townsend
(PI),
Chan-yu Wu (Co-PI),
Jae Hac Ko (Post Doctoral
Associate),
Wes Oehming(Student)
Sponsored by:
Hinkley Center for Solid and Hazardous Waste Management
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