Ex situ vitrification

Geotech Development Corporation offers a proprietary Cold Top ex situ vitrification process for the treatment of contaminated soil. The system melts the soil using an electric resistance furnace that can operate at temperatures of up to 5200°F. The vendor claims that wastes are transformed into an essentially monolithic, vitrified mass. The process is termed cold top vitrification because soil is added to the top of the melt to act as an insulator and to minimize the loss of volatile metals into the off-gas treatment system. The technology has been evaluated in a pilot-scale facility and is commercially available. 

MeItTran, Inc. (MeItTran), has developed the Ultimate Solution, an ex situ vitrification technology that uses a direct current (DC) arc system to treat hazardous wastes. The vendor claims that organic materials are destroyed by the technology and that inorganic materials are melted and cooled into a leach-resistant final waste form. RIMS were unable to obtain information from the vendor in regards to performance or commercial availability. 

Vitrification technologies may be ex situ or in situ. In ex situ vitrification, any soils, sediments, or buried wastes are excavated. After possible pretreatment to reduce arsenic volatilization, the materials are placed in a furnace and melted at temperatures as high as 2000 °C. The heat may be generated by fossil fuels, electricity, plasma torches, or microwaves (US EPA), 2002a, 5.1). 

Soil treatment, 25 834-843, 843-845 bioremediation, 25 835-836 electrokinetics, 25 843-844 ex situ bioremediation, 25 836, 842-843 in situ air stripping, 25 844 in situ bioremediation, 25 836-842 plume containment, 25 835 soil flushing, 25 844 soil vapor extraction, 25 844 sulfur use in, 23 591 vitrification, 25 844-845 Soil-vapor extraction defined, 3 759t... 

Electro-Pyrolysis, Inc. (EPI) has developed the direct current (DC) graphite arc furnace vitrification technology for the ex situ treatment of wastes. The arc furnace can be operated as an oxidation or reduction process. The vendor states that DC arc melter treatment produces a leach-resistant solid and reduces the volume of wastes that require disposal. 

EM C Engineering Associates markets the Vitriflux vitrification system for the treatment of hazardous wastes. The vendor claims that the unique feature of this vitrification system is that fluxing material is added to achieve vitrification at relatively low temperatures. Although this technology has only been tested as an ex situ process, the developer claims that in situ treatment is possible. 

Ex Situ Joule-Heated Vitrification, Envitco, Inc In undated vendor literature supplied in 1997, Davis estimates that treating a hazardous waste incinerator waste stream would cost from 131.30 to 266.90 per ton of dry waste treated. This cost estimate is summarized in Table 1. Costs vary depending on feed rate and the degree of waste reduction achieved during treatment. The estimate... 

Plasma vitrification systems can heat the waste in one of two ways either as a nontransferred arc or as a transferred arc. A nontransferred arc uses two internal electrodes. A small column of injected gas is heated by the electric arc, creating a plasma flow that extends beyond the tip of the torch. Nontransferred arcs heat by conduction and produce a dispersed heat that heats both the waste and the gas around the waste. Nontransferred arc melters can operate as in situ or ex situ processes (D11008N, pp. 3-7, 3-11). 

The RIMS library/database contains many technologies that can be operated in a pyrolysis mode. They include both in situ and ex situ methods, vitrification techniques, as well as technologies used for gasification. A list of these technologies can be found by searching under the technology category pyrolysis. ... 

Electrokinetic method Refers to an in situ, and sometimes an ex situ, technology that removes contaminants from wet soils and sediments by passing electric currents through them. Unlike in situ vitrification, the currents in electrokinetic methods are too low to melt the materials. Instead, the electric currents cause contaminant ions and charged particles in aqueous solutions within the solid materials to migrate towards the electrodes, where they may be collected or otherwise treated. 

Metal(loid)-contaminated soil can be remediated by chemical, physical, or biological techniques (or a combination of all three). The technology applied is often specific to the metal(loid) contaminant to be removed and the site characteristics and may be further classified into in situ and ex situ categories. In situ remediation takes place on site and does not require excavation of the contaminated soil, limiting the exposure pathways to other organisms, including humans. Many in situ teclmiques aim to stabilize the metal(loid) fraction in the soil via specific soil amendments (e g., lime), vitrification, electrokinetics, solidification (thermal treatments) or passive remediation methods. Such techniques do not reduce the total... 

Certain site requirements are necessary to prepare the contaminated area for vitrification. Measures include site preparation for the equipment, which may include clearing vegetation and any overburden. Regardless of whether the application is performed in or ex situ, backfill will be required, because the vitreous mass is smaller than the original waste volume. 

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