Savannah River Site Waste Management Final Environmental Impact Statement

Appendix D

SUMMARY

This appendix to the Waste Management Environmental Impact Statement (eis) provides summaries of innovative and emerging technologies being evaluated at Savannah River Site (SRS) and other locations that have the potential for treating hazardous, radioactive, or mixed (hazardous and radioactive) wastes at SRS. This eis considered 85 technologies, many of which were screened out during the options analysis process described in Section 2.3 of this eis. This appendix discusses many of those technologies that were eliminated from detailed consideration in Section 2.3 as well as some developing technologies that were not considered in Section 2.3.

Many of these technologies are either not commercially available, have not undergone demonstrations for the waste types at SRS, or have not been shown to be either economically or technically viable (i.e., have not achieved engineering breakthrough). However, some of the 26 emerging technologies described in this appendix may prove viable in the future and may be chosen for more detailed design and operations analyses based on the outcome of demonstrations. The in-depth options analysis used to select treatment technologies was biased towards choosing proven solutions to U.S. Department of Energy (DOE) waste management issues. As other technologies mature, these may warrant consideration.

The technologies summarized here treat contaminated matrices that contain plastic, paper (and other forest products), metals, aqueous liquids, and organic liquids. These waste matrices are generated through activities such as site operations, decontamination and decommissioning, or environmental restoration. Some technologies have been available for years, but application of the technology to waste management would be considered innovative.

The treatment summaries were prepared from a number of literature sources and interviews and have been grouped by categories of waste treatment: (1) biological, (2) chemical, (3) physical, (4) stabilization, and (5) thermal.

D.1 Background

This appendix provides summaries of 52 innovative and emerging technologies that have the potential for treating hazardous, radioactive, or mixed (hazardous and radioactive) wastes at SRS. Eighty-five technologies were considered, many of which were screened out during the options analysis process described in Section 2.3 of the eis. Table D-1 defines each of the technologies and identifies its purpose (volume reduction, stabilization, or decontamination). For the most part, the technologies discussed in this appendix are not commercially available, have not undergone full-scale demonstrations for the waste types present at SRS, or have not been shown to be either economically or technically viable. However, many of the emerging technologies described in this appendix may prove viable in the future and may be chosen for more detailed design and operations analyses based on the outcome of fullscale demonstrations, other commercial applications, or use by the U.S. Department of Energy (DOE) on similar wastes.

Section 2.3 of the eis evaluated 85 processes and technologies in 5 treatment categories. The treatment categories used in the prescreening process (biological, chemical, physical, stabilization, and thermal) are also used in this appendix for consistency. The treatment categories include both conventional and emerging processes and technologies. Some examples of conventional processes include evaporation, compaction, storage, and incineration. These types of processes are not addressed in this appendix. Examples of innovative technologies include electrodialysis, plasma torch, supercritical water oxidation, and white rot fungus. These types of innovative and emerging technologies are addressed in detail in this appendix.

Table D-2 provides a comparison of 26 innovative technologies included in Section 2.3 with those in Appendix D. Several of the process technologies identified in Section 2.3 are subdivided into more discrete technologies discussed in Appendix D. For example, Section 2.3 identified the technology process of fluidized bed incineration (number 13 on Table D-2); Appendix D identifies two specific subtypes of fluidized bed incineration. Appendix D also identifies six emerging technologies [acoustic barrier particle separator (D.5.1), high-energy electron irradiation (D.5.8), gas-phase chemical reduction (D.4.4), nitrate to ammonia and ceramic process (D.4.5), electrochemical oxidation (D.4.12), and mediated electrochemical oxidation (D.4.13)] that are not specifically addressed in Section 2.3.

Innovative technologies for treating radioactive, hazardous, and mixed wastes are currently being developed and demonstrated by DOE and the U.S. Environmental Protection Agency (EPA). DOE demonstrations generally focus on radioactive and mixed waste treatments and are funded by the DOE Office of Technology Development (EM-50) through the Mixed Waste and Landfill Focus Areas. Technologies are developed and demonstrated at the eight national laboratories.

EPA technology demonstrations are supported by the Risk Reduction Engineering Laboratory and the Superfund Innovative Treatment Evaluation program. Most Superfund Innovative Treatment Evaluation demonstrations focus on hazardous wastes generated at Superfund sites. Many of the technologies evaluated by the Superfund Innovative Treatment Evaluation program may be applicable to radioactive and mixed wastes.

SRS generates large quantities of solid low-level radioactive waste, and currently utilizes vault or shallow land disposal. Most solid low-level radioactive waste is job-control waste, a fraction of which is compacted on site prior to vault disposal. Several technologies described in this appendix can potentially be used to reduce the volume and stabilize solid low-level radioactive waste. Stabilization would minimize potential radionuclide migration following direct shallow land disposal. Hazardous wastes generated at SRS include organic and aqueous liquids, most of which are treated and taken off site for disposal. Mixed wastes, which include most of the matrices described above, are being stored until adequate treatment and disposal capacity is identified at SRS or offsite.

Wastes containing greater than 100 nanocuries per gram of transuranic alpha-emitting radionuclides with half-lives greater than 20 years are considered transuranic wastes. These wastes pose special handling, storage, and disposal problems due to the inhalation and ingestion risks posed by alpha particles and to long half-lives and potential criticality concerns from plutonium radionuclides. DOE plans to ship transuranic wastes for disposal at the Waste Isolation Pilot Plant, located near Carlsbad, New Mexico. The earliest projected date for the Waste Isolation Pilot Plant to begin disposing of these wastes is 1998. Although transuranic wastes are not required by law to be treated or stabilized, treatment and conversion of these wastes to a stabilized waste form (such as glass or slag) could reduce the volume of the wastes and minimize potential releases and human and environmental exposures during onsite storage, prior to disposal at the Waste Isolation Pilot Plant. Disposal of mixed transuranic wastes at the Waste Isolation Pilot Plant is dependent on a Resource Conservation and Recovery Act (RCRA) no-migration petition being granted by the State of New Mexico and EPA.

DOE is currently funding several technology development projects at SRS through the Savannah River Technology Center and the Vendor Forum program, both of which are managed by the Westinghouse Savannah River Company. Many Savannah River Technology Center projects are conducted jointly with universities (such as Clemson University and Georgia Institute of Technology) and industrial partners. Innovative technology programs funded at SRS include plasma arc treatment of solid low-level radioactive waste, vitrification of various waste forms using a portable vitrification unit, noble metal reclamation from electronic components, dechlorinating radioactive polychlorinated biphenyls (PCBs) in a solid matrix, extraction of uranium from contaminated soil, treatment of tritiated oils and groundwater, acoustic wave treatment, and waste stabilization using several different binders.

EPA and DOE recently collaborated at SRS on a Superfund Innovative Treatment Evaluation project to demonstrate the feasibility of treating contaminated groundwater with an electron beam. Contaminated groundwater was pumped past the beam to determine destruction efficiencies of hazardous organics at different electron beam dose rates.

Table D-1. Technologies considered for treatment of SRS waste.

Technology purpose
1^a	2^b	3^c	Technology and description
	_		Abrasive blasting - a process in which solids such as sand or dry ice pellets in a pressurized fluid matrix are sprayed against a radiologically contaminated surface to decontaminate the surface.
		_	Acid/base digestion, solids dissolution - a process to dissolve solids in an acid/base bath in the presence of a metal catalyst to remove contaminants. The dissolved metal solution would then be treated via chemical precipitation for removal of the metal.
_		_	Asphalt based microencapsulation - a thermally driven process to dewater a waste and trap the residual solids in a liquid asphalt matrix that solidifies for disposal.
		_	Absorption - the transfer of contamination that is mixed with one phase into another phase.
		_	Aerobic biotreatment - the use of aerobic bacteria in a bioreactor to remove aromatic organic contaminants from soilssoils, sediments, and sludges.
		_	Alkaline chlorination - an emerging application of the dechlorination technology. The technology involves dechlorination of halogenated compounds such as polychlorinated biphenyls and other chlorinated compounds by a substitution reaction. The secondary wastes from the reaction require disposal.
		_	Activated sludge - the use of an activated sludge material like an activated charcoal for the removal of organic materials from wastes.
		_	Anaerobic digestion - the use of nonaerobic bacteria (i.e., bacteria that do not require oxygen) in a bioreactor for the consumption of specific organic contaminants from aqueous wastes.
_		_	Advanced electrical reactor - a graphite electrode DC arc furnace in which two electrodes are attached to the waste being processed. A plasma arc is generated between the electrodes that generates 1700ºC temperatures, causing the soil/metal mixture to be stratified into a metal phase, a glass phase, and a gas phase. The phases are separated and treated separately.
		_	Air stripping - used for the removal of volatile organic compounds from aqueous waste streams. The liquid waste is intimately contacted with air resulting in mass transfer of the organic compound from liquid phase to the gas phase.
		_	AmalgamationAmalgamation - the property of mercurymercury in which it unites or alloys with other metals. This is used in the tritiumtritium production process where gold traps remove mercury.
		_	Alkali metal dechlorination - an emerging application of the dechlorination technology. The technology involves dechlorination of halogenated compounds such as polychlorinated biphenyls and other chlorinated compounds by a substitution reaction. The secondary wastes from the reaction require disposal.
		_	Alkali metal/polyethylene glycol - an emerging application of the dechlorination technology. The technology involves dechlorination of halogenated compounds such as polychlorinated biphenyls and other chlorinated compounds by a substitution reaction. The secondary wastes from the reaction require disposal.
		_	Blast furnaces - used together with reverberatory furnaces for the removal of lead from excavated materials. Also see smelting.

Table D-1. (continued).

Technology purpose
1	2	3	Technology and description
		_	Bio-reclamation - or bioremediation is a normally in situ process whereby biological agents that degrade hydrocarbons are mixed with organically contaminated soil to remove these contaminants from the soil.
		_	Carbon adsorption - the use of a bed of granular activated carbon or charcoal for the removal of chlorinated hydrocarbons, aromatic solvents, and fuels from an aqueous waste.
		_	Circulation bed combustion - uses high velocity air to entrain circulating solids and create a highly turbulent combustion zone that destroys toxic hydrocarbons such as PCBs.
		_	Catalytic dehydrochlorination - an emerging application of the dechlorination technology. The technology involves dechlorination of halogenated compounds such as polychlorinated biphenyls and other chlorinated compounds by a substitution reaction. The secondary wastes from the reaction require disposal.
		_	Cementation - a process in which contaminated wastewaterwastewater is mixed with cement to solidify and stabilize the contaminants for storage.
		_	Centrifugation - the use of a centrifuge to separate solids from a liquid waste for further processing.
		_	Chemical hydrolysis - the use of a reactive chemical species in water to detoxify or neutralize the hazardous constituents. This is usually used for the recovery of spent solvents.
		_	Chelation - an ion exchangeion exchange process in which the exchange media possesses unusually high selectivity for certain cations.
		_	Chemical oxidation/reduction - the use of a variety of oxidation or reduction processes for the removal of contaminants from waste materials/processes.
		_	Compaction - the use of a mechanical device, normally hydraulically operated, to reduce the volume of waste before its disposal. CompactorsCompactors generate less than 1,000 tons of compressive force.
		_	Chemical precipitation - removes dissolved hazardous metal species from water to permit conventional water disposal through a permitted outfall. The solution is mixed with chemical additives that cause the generation of insoluble compounds of the metal which can then be filtered.
		_	Crystallization - the removal of dissolved solids from solution by subcooling the solution either directly or indirectly to a temperature lower than the pure component freezing point of the dissolved solid. This may be accomplished with or without the addition of a diluent solvent.
		_	Dissolved air flotation - an adsorptive-bubble separation method in which dissolved air is used for the removal of solid particulate contaminants.
		_	Distillation - a process for the removal of solid contaminants from solution by separating the constituents of the liquid mixture via partial vaporization of the mixture and the separate recovery of the vapor and the solid contaminant residue.

Table D-1. (continued).

Technology purpose
1	2	3	Technology and description
		_	Electrodialysis - a process for the removal of dissolved ionic contaminants from solution by pumping the solution through very narrow compartments that are separated by alternating charged cation-exchange and anion-exchange electrode membranes which are selectively permeable to positive and negative ions, respectively.
		_	Evaporation - the removal of water via vaporization from aqueous solutions of nonvolatile substances, thus leaving the residual contaminant for further processing for disposal.
		_	Fluidized bed incinerator - an incinerator in which the solid waste particles are held in suspension via the injection of air at the bottom of the bed (complete destruction of the waste) or an incinerator in which a bed of limestone material is held in suspension as waste is incinerated to induce chemical capture to form stable compounds which can be readily disposed of.
		_	Filtration - the process in which fluid is passed through a medium which traps and thus removes solid particles from the fluid stream.
		_	Flocculation - the use of fine particles that are anionically or cationically charged for ion removal that aggregate into a larger mass, that can be filtered out, as the ion exchangeion exchange process occurs.
		_	High temperature metal recovery - the use of smelting or blast furnaces for the recovery of metals such as lead.
		_	Heavy media separation - a process that takes advantage of the presence of a waste constituent that is heavier than the others by using any of a number of available methodologies for segregation of the heavier constituent.
	_		High pressure water steam/spray - used for the decontamination of surfaces having loosely held contamination. One of these methods is commonly known as hydrolazing.
		_	Industrial boilers - used for the burning of permitted organic wasteorganic wastes for energy recovery.
		_	Ion exchangeIon exchange - a process in which a bed of solid resin material carrying an ionic charge (+ or -) accompanied by displaceable ions of opposite charge is used to displace metal ions dissolved in the solution flowing through the resin bed, thus removing the metals from the solution.
		_	Industrial kilns - see industrial boilers above.
		_	Lime-based pozzolans - a solidification and stabilization process that takes advantage of siliceous or aluminous materials that react chemically with lime at ordinary temperatures in the presence of moisture to produce a strong cement. The process is used for contaminated soilssoils, sludges, ashes, and other similar wastes.
		_	Liquid/liquid extraction - a process for separating components in solution via the transfer of mass from one immiscible liquid phase into a second immiscible liquid phase.
		_	Liquid injection incinerators - an incinerator used for the destruction of liquid organic wasteorganic wastes only.
		_	MacroencapsulationMacroencapsulation - the coating or containing of a solid waste form with another material to stabilize the waste form.

Table D-1. (continued).

Technology purpose
1	2	3	Technology and description
_		_	Molten glass - the product resulting from the vitrificationvitrification process where waste solids are exposed to high temperatures. The molten glass is allowed to cool to a homogeneous, nonleachable solid for disposal.
_		_	Microwave solidification - a process which uses microwave energy to heat and melt homogeneous wet or dry solids into a vitrified final waste form that possesses high-density and leach-resistant attributes.
		_	Molten salt destruction - a process for destruction of organic wasteorganic waste constituents where the waste is injected into a molten bed of salt along with an oxidizing gas such as air. The organics are destroyed and the residual molten salts are drained and dissolved in water for further processing.
		_	Neutralization - normally the addition of an acid to an alkaline solution to initiate the precipitation of contaminants.
		_	Oxidation by hydrogen peroxide - an organic contaminant removal process that uses hydrogen peroxide to oxidize the contaminants for removal.
		_	Oil/water separation - the process by which a mechanical device removes oil from water by taking advantage of the density difference that causes it to float on water.
		_	Ozonation - a chemical oxidation process in which ozone, an oxidizing agent, is added to a waste to oxidize organic materials into carbon dioxide and water vapor. This offgas would be passed through a carbon bed for the removal of generated volatile organic vapors.
_		_	Polymerization - a thermally driven process to dewater a waste and trap the residual solids in a liquid polymer matrix that solidifies for disposal.
		_	Phase separation - any process that takes advantage of the presence of two phases in a waste stream or waste product to segregate one of the phases from the other.
_		_	Plasma arc torch - used as the heat source for a vitrificationvitrification process in which the waste is fed into a centrifuge in which the plasma torch is installed, where it is uniformly heated and mixed.
_		_	Pyrolysis - the use of extremely high temperatures for the destruction of organic contaminants and the fusion of inorganic waste into a homogeneous, nonleachable glass matrix.
		_	Rotating biocontactors - a bioremediation process in which the biological reactor body rotates to enhance the mixing and contact of the waste with the biological agents.
_			Recycle - the process by which any substance, material, or object is processed for reuse.
_			Repackaging/containerize - the process by which waste is resorted and placed in containers that result in increased space-efficiency and cost-effectiveness for disposal.
_		_	Rotary kiln incinerator - an incinerator that uses a rotating kiln body for the burning of the waste material being fed.
		_	Reverse osmosis - separates hazardous constituents from a solution by forcing the water to flow through a membrane by applying a pressure greater than the normal osmotic pressure.

Table D-1. (continued).

Technology purpose
1	2	3	Technology and description
		_	Roasting/retorting - the oxidation and driving off of solid contaminants via the use of high temperatures.
		_	Super critical extraction - a process for the extraction of organic contaminants from waste products via the use of a reactor in which the temperature and pressure are elevated to values greater than the triple point of water.
		_	Solvent extraction - a process whereby solvents or liquefied gases (such as propane or carbon dioxide) are used to extract organics from sludges, contaminated soilssoils, and waste water.
	_		Sealing - the process that is used to trap surface contamination to a surface from which it is not readily removable. The surface is coated with a matrix that seals the contamination in place.
		_	Sedimentation - the partial separation or concentration of suspended solid waste particles from a liquid by gravity settling.
		_	Soil flushing/washing - a process in which water and chemical additives are added to contaminated soil to produce a slurry feed to a scrubbing machine that removes contaminated silts and clay from granular soil particles.
	_		Scarification/grinding/planing - the use of a high speed rotating mechanical device for the removal of fixed surface contamination.
_			Shredding/size reduction - the process by which a shredder is used to cut contaminated paper, plastics, cardboard, etc. into smaller pieces to provide volume reduction prior to disposal.
		_	Smelting - used to treat stainless steel for the removal of radionuclides. The stainless steel is fed into reverberatory or blast furnaces with additives which serve to separate the radionuclides from the slag, leaving clean metal.
		_	Sorption - the selective transfer of one or more solutes or contaminants from a fluid phase to a batch of rigid particles.
	_		Spalling - the use of a mechanical impact device to chip away a contaminated surface. The surface is spalled to a depth that is no longer contaminated and the chipped debris is disposed of.
_			Sorting/reclassifying - the process by which waste is sorted to optimize the way in which it is disposed to provide for the most space efficient and cost effective packaging of the waste.
		_	Steam stripping - the use of superheated steam to oxidize complex organic compounds to carbon monoxide, carbon dioxide, water, hydrogen, and methane. The destruction of the organics is then completed at high temperature using an electrically heated reactor.
		_	Supercritical water oxidation - an aqueous phase oxidation treatment in which organic wasteorganic waste, water, and an oxidant (air or oxygen) are combined in a tubular reactor at temperatures above the critical point of water.
_			Supercompaction - the use of a compactor that has a capacity of greater than 1,000 tons compressive force for increased volume reduction and the compaction of items not effectively compacted by a normal compactor.

Table D-1. (continued).

Technology purpose
1	2	3	Technology and description
		_	Thermal desorption - a process used for the removal of organics from sludges at a temperature of 350 - 600ºF which is high enough to volatilize the organics for adsorption capture but low enough to prevent the emission of significant quantities of metals that can occur with incinerationincineration.
		_	UV photolysis - a process that removes organic contaminants from aqueous waste streams via the use of ultra-violet radiation to oxidize the contaminants.
	_		Vibratory finishing - the use of a mechanical vibratory tool for the decontamination of surfaces having fixed contamination.
_		_	VitrificationVitrification - a high temperature process by which waste is treated in a furnace at temperatures which drive off organics for further treatment and reduce the inorganic waste to a homogeneous, nonleachable glass slag that is discharged into a mold or drum for disposal.
		_	Wet air oxidation - a process in which the waste is heated and passed, along with compressed air, into an oxidation reactor where oxidation of the organic contaminants takes place.
		_	White rot fungus - a lignin-degrading fungi that is used to inoculate organic materials which are mechanically mixed with contaminated soilssoils to break down the contaminants.
	_		Water washing/spraying - the use of low pressure water to rinse contaminated surfaces for the removal of loosely held contamination.

a. Volume reduction.

b. Decontamination.

c. Immobilization/stabilization.

Table D-2. Comparison of Section 2.3 process technologies and Appendix D technologies.

Section 2.3		Corresponding Appendix D
Type/Technology		Type/Technology
1. Physical/Electrodialysis		Physical/Electrodialysis
2. Physical/Evaporation		Chemical/Evaporation and Catalytic Oxidation
3. Physical/Sedimentation and Flocculation		Physical/Binding, Precipitation, and Physical Separation
4. Physical/High Pressure H20 Steam/Spray		Physical/Pressure Washing and Hydraulic Jetting
5. Physical/Ion Exchange		Chemical/Resorcinol-Formaldehyde Ion Exchange Resin
6. Physical/Soil Flushing/Washing		Physical/Soil Washing
7. Physical/Steam Stripping		Physical/Steam Reforming
8. Physical/Filtration		Physical/Chemical Treatment, and Ultrafiltration; Heavy Metals and Radionuclide Polishing Filter; Membrane Microfiltration
9. Stabilization/Lime-Based Pozzolans		Stabilization/Pozzolaric Solidification
10. Stabilization/Polymerization		Stabilization/Polyethylene Encapsulation Stabilization/Vinyl/Ester Styrene Solidification
11. Stabilization/VitrificationVitrification		Thermal/Electric Melter VitrificationVitrification Thermal/Stirred Melter Vitrification Thermal/Modular Vitrification Thermal/In-Situ Vitrification Thermal//Vortec Process
12. Thermal/Advanced Electrical Reactor		Thermal/Graphite Electrode DC Arc Furnace Thermal/Packed Bed Reactor, Silent Discharge Plasma Apparatus
13. Thermal/Fluidized Bed Incinerator		Thermal/Fluidized Bed Cyclonic Agglomerating Incinerator Thermal/Catalytic Combustion in a Fluidized Bed Reactor
14. Thermal/High Temperature Metal Recovery		Thermal/Quantum-Catalytic Extraction Process
15. Thermal/Molten Glass		Thermal/Electric Melter VitrificationVitrification Thermal/Stirred Melter Vitrification Thermal/Modular Vitrification
16. Thermal/Molten Salt Destruction		Thermal/Molten Salt Oxidation and Destruction Process
17. Thermal/Infrared Incinerators		Thermal/Infrared Thermal Destruction
18. Thermal/Circulating Bed Combustion		Thermal/Cyclonic Furnace
19. Thermal/Supercritical Water Oxidation		Chemical/Supercritical Water Oxidation
20. Thermal/Wet Air Oxidation		Thermal/Wet Air Oxidation
21. Biological/Aerobic Biotreatment		Biological/Bioscrubber Biological/Biosoprtion
22. Biological/White Rot Fungus		Biological/White Rot Fungus
23. Chemical/Alkali Metal Dechlorination, Alkali metal/ Polyethylene glycol		Chemical/Dechlorination
24. Chemical/Catalytic Dehydrochlorination		Chemical/Aqueous Phase Catalytic Exchange Evaporation and Catalytic Oxidation Biocatalytic Destruction
25. Chemical/Crystallization		Physical/Freeze Crystallization
26. Chemical/Ultraviolet Photolysis		Physical/Ultraviolet Oxidation

D.2 Introduction

Table D-3 provides summary information by technology type, technology, the development status of the technology, the type of waste that can be treated by the technology, and the waste form generated by the technology for all technologies addressed in this appendix. Most of these technologies are still at the bench, pilot, or demonstration stage of development and are not commercially available. The technologies summarized here treat contaminated matrices that contain plastic, paper (and other forest products), metals, aqueous liquids, and organic liquids. These waste matrices are generated through activities such as site operations, decontamination and decommissioning, or environmental restoration. Some technologies, such as vitrification and plasma furnaces, have been available for years. Vitrification of liquid high-level radioactive waste is a proven technology.

D.3 Biological Treatment Technologies

Biological treatment methods have been used to treat organic wastes for years. These methods rely on microorganisms to degrade organic compounds to simpler compounds (such as carbon dioxide and water). Sanitary waste water treatment plants rely on biological methods to treat domestic waste water prior to its discharge to surface water. Several industrial wastewaters (such as phenolic and pulp and paper wastes) are also treated using biological methods. Complete degradation (mineralization) of complex hydrocarbons (such as PCBs or polyaromatic hydrocarbons) is more difficult to achieve. Degradation rates are controlled by energy available from breaking chemical bonds and factors affecting enzymatic activity (such as water solubility, pH, temperature, and metals concentration). In general, biological treatment methods are effective for many simple, water-soluble organics. Biological treatment of aqueous-phase organics in industrial wastes often results in the production of sludges contaminated with heavy metals (such as cadmium and lead). These technologies are generally most effective for relatively homogeneous wastes in dilute aqueous solutions.

Innovative approaches to biological treatments include in situ treatment of contaminated groundwater by alternating aerobic (in the presence of oxygen) and anaerobic (without oxygen) conditions using microorganisms (such as white rot fungus, which may be more effective for hydrophobic compounds), and special techniques (such as special reactor vessels, co-substrates, and nutrients) to select microorganisms for optimal degradation rates of compounds that are difficult to treat.

D.3.1 BIOSCRUBBER

The bioscrubber technology removes organic contaminants in air streams from soil, water, or air decontamination processes and is especially suited to wastes containing dilute aromatic solvents at relatively constant concentrations. The bioscrubber technology digests trace organic emissions using a filter with an activated carbon medium that supports microbial growth. The bioactive medium converts diluted organics into carbon dioxide, water, and other nonhazardous compounds. The filter provides biomass removal, nutrient supplement, and moisture addition. Recently developed bioscrubbers have a potential biodegradation efficiency 40 to 80 times greater than existing filters. A disadvantage of the bioscrubber is its inability to treat high concentrations of aromatics at a high capacity, as required by systems at SRS. A pilot-scale unit with a 4cubicfootperminute capacity is currently being field tested for the EPA's Superfund Innovative Treatment Evaluation Emerging Technology Program. The bench-scale bioscrubbers successfully removed trace concentrations of toluene at greater than a 95 percent removal efficiency (EPA 1993).

D.3.2 BIOSORPTION

Biosorption is a process by which specialized bacteria are used to biosorb radionuclides and metals. Biosorption consists of the separation and volume-reduction of dilute aqueous-phase radionuclides, metals, and nitrate salts. Liquids and salts are fed to a bioreaction system where radionuclides and metals are concentrated and supernated through biosorption by specialized bacteria. The microorganisms are grown in a bioreactor and are recycled to a biosorption tank where they are mixed with the liquids and salts. Microorganisms biosorb the metals and radionuclides and are removed by filtration to generate a biomass sludge that can be volume-reduced and stabilized through incineration or vitrification. The filtrate, which contains nitrate salts, organics, and low levels of metals, flows to the bioreactor where the nitrate salts are reduced to nitrogen gas and bicarbonate solution and any remaining metals are further adsorbed by the bacteria. After filtration, the effluent from the bioreactor is a salt solution. The process is anticipated to be safe (the system operates at standard temperature and pressure with natural bacteria), energy-efficient, and cost-effective. Uncertainties include potential toxic effects of radionuclides and metals on the bacteria and the volume and characteristics of the sludge. Biosorption of residual underground tank surrogate waste has been demonstrated in the laboratory and is currently in scale-up design for field demonstration at the Idaho National Engineering Laboratory (DOE 1993, 1994a, b).

D.3.3 WHITE ROT FUNGUS

White rot fungus (Phanerochaete chrysosporium) is used to degrade a variety of carbon-based contaminants, including PCBs, chlorinated solvents, hydrocarbons, and cyanide. The naturally occurring fungi degrade the contaminants to byproducts, such as inorganic salts, carbon dioxide and water. The ability of this fungus to biodegrade contaminants can be attributed, at least in part, to its natural lignin-degrading system that it uses to decay fallen trees to provide its primary food source, cellulose.

In order to support sustained degradation of chemicals, a carbon source for the fungi must be present and readily available. Examples of bulking agents that can serve as a carbon source include wood chips, corn cobs, and other complex carbohydrates. Degradation rates increase with pollutant chemical concentration, and the toxicity of the chemicals rarely affects the fungi. The microorganisms are able to survive and grow in many adverse conditions and substances, including used 20-weight motor oil and coal-tar-contaminated soils.

A waste treatment system based on white rot fungus can degrade many recalcitrant environmental organic pollutants. The white rot fungus treatment method offers the ability to treat a wide variety of chemical organic pollutants. This treatment method is still in research and development stages. However, experimental results indicate that high degradation of many common pollutants (including pesticides, herbicides, and dyes) is possible. However, the application of this technology to radioactive and mixed wastes may be limited due to potential radiological effects on the white rot fungus organism.

Bench-scale testing of white rot fungus treatment was conducted under a cooperative agreement with the EPA (Connors, no date; Bumpus et al. 1989).

D.4 Chemical Treatment Technology

Chemical treatment methods have traditionally been used to treat virtually all types of wastes. These methods can be applied to hazardous, radioactive, and mixed wastes and are compatible with liquids, solids, sludges, and gases.

There are two basic types of chemical treatment methods, chemical extraction and chemical destruction. Chemical extraction technologies separate the contaminants from the waste, while chemical destruction technologies either destroy the hazardous constituent or remove the hazardous characteristic. The type of chemical treatment method applied to a waste stream depends on its physical and chemical properties, regulatory requirements, secondary waste disposal options, and performance assessments.

Innovative approaches to chemical treatment include oxidation/reduction methods (such as supercritical water oxidation, ultraviolet oxidation, and low-temperature reduction of nitrate in ammonia) and the use of newly developed ion exchange resins.

Electrochemical treatment is a direct oxidation/reduction process that is used to treat liquid wastes containing recoverable metals or cyanide. This process involves immersing cathodes and anodes in a waste liquid and introducing a direct electric current. Electrolytic recovery of single metal species can be high and may yield pure or nearly pure forms. Process times are a function of variables such as purity desired, electrode potential, and current, electrode surface area, ionic concentrations, and agitation.

DOE is developing innovative electrochemical treatment processes to demonstrate oxidation of organics and the biocatalytic destruction of nitrate and nitrite salts.

D.4.1 AQUEOUS-PHASE CATALYTIC EXCHANGE FOR DETRITIATION OF WATER

The aqueous-phase catalytic exchange method was originally used to remove organics from waste streams in closed-environment systems. Aqueous-phase catalysis is also applicable to the detritiation of aqueous wastes, and experiments have shown that this process may be able to lower contaminated groundwater tritium levels by two orders of magnitude with an acceptable catalyst bed lifetime. DOE has recently proposed an expansion of its testing of aqueous-phase catalysis. A catalyst manufactured in the United States will be evaluated for use in detritiation of waste water from SRS and other DOE facilities. Performance comparisons will be made with a Canadian-manufactured catalyst (Sturm 1994).

D.4.2 BIOLOGICAL/CHEMICAL TReaTMENT

The biological/chemical treatment technology involves a two-stage process to treat wastes contaminated with organics and metals. The process includes chemical leaching of the waste to remove metals (this is similar to soil-washing techniques or mixed ore metals extraction) and bioremediation to remove organics and metals. The process results in an end product of recovered, salable metal or metal salts, biodegraded organic compounds, and stabilized residues. The incoming waste is first exposed to the leaching solution and filtered to separate oversized particles. The leaching solution disassociates metal compounds from the waste. The metal compounds form metal ions in the aqueous leachate and can be removed by liquid ion exchange, resin ion exchange, or oxidation/reduction. After the metals are extracted, the slurried waste is allowed to settle and neutralize. Next, the slurry is transferred to a bioreactor where micronutrients are added to support microbial growth and initiate biodegradation. The residual leaching solution and biodegradable organic compounds are aerobically degraded in the bioreactor. The combined metal leaching and bioremediation processes may be less expensive than separate processes. For treatment of organic compounds, chemical treatment may facilitate biological treatment, especially for PCBs. Bench-scale tests conducted for the EPA's Superfund Innovative Treatment Evaluation Emerging Technology Programs show that a variety of heavy metals and organic pollutants can be remediated by the process. Pilot-scale testing of the process is being conducted (EPA 1993).

D.4.3 DECHLORINATION

The Dechlor/KGME process involves the dechlorination of liquid-phase halogenated compounds, particularly PCBs. KGME, a proprietary reagent, is the active species in a nucleophilic substitution reaction in which the chlorine atoms on the halogenated compounds are replaced with fragments of the reagent. The products of the reaction are a substituted aromatic compound (which is no longer a PCB aroclor) and an inorganic chloride salt. These secondary wastes require treatment and disposal.

KGME is the potassium derivative of 2-methoxyethanol (glyme) and is generated in situ by adding stoichiometric quantities of potassium hydroxide (KOH) and glyme. The KOH and glyme are added to a reactor vessel along with the contaminated waste. The KGME is formed by slowly raising the temperature of the reaction mixture to about 110 °C, although higher temperatures can be beneficial.

The reaction product mixture is a fairly viscous solution containing reaction products and the unreacted excess reagent. After this mixture has cooled to about 93ºC (199ºF), water is added to help quench the reaction and extract the inorganic salts from the organic phase.

The DeChlor/KGME process is applicable to liquid-phase halogenated aromatic compounds, including PCBs, chlorobenzenes, polychlorinated dibenzodioxins, and polychlorinated dibenzofurans. Waste streams containing from less than 1 to up to 1,000,000 parts per million (100 percent) of PCBs can be treated. Laboratory tests have shown destruction removal efficiencies greater than 99.98 percent for materials containing 220,000 parts per million of PCBs (22 percent).

DOE has recently proposed to evaluate this process for treating solid waste contaminated with PCBs and radioactivity. Although this technology has been demonstrated for treatment of liquid PCB wastes, it has not been demonstrated for treating porous, fine-grained solids contaminated with PCBs.

PCB-contaminated radioactive wastes are currently stored at several DOE facilities. Due to the capacity limitations of the Oak Ridge incinerator regulated by the Toxic Substances Control Act and RCRA, the mixed wastes will be stored for more than 10 years before they can be disposed of. The Consolidated Incineration Facility at SRS is not permitted to incinerate PCB wastes; however, this is a viable option. The Dechlor/KGME process may be an alternative to incineration and long-term storage. However, some secondary wastes would still require disposal.

Laboratory testing will be conducted with nonradioactive surrogate materials, and if the results are acceptable, additional testing will be performed on representative radioactive waste samples. Pilot-scale testing of the Dechlor/KGME process can then be carried out to evaluate the efficiency of PCB destruction and the suitability of the process for treating nonradioactive surrogate waste (EPA 1991).

D.4.4 GAS-PHASE CHEMICAL REDUCTION

The gas-phase chemical reduction process uses a gas-phase reduction reaction of hydrogen with organic compounds at elevated temperatures. The process occurs at elevated temperatures to convert aqueous and oily hazardous contaminants to a gaseous, hydrocarbon-rich product. A mixture of atomized waste, steam, and hydrogen is injected into a specially designed reactor. The hydrogen must be specially handled to prevent any potential for explosion. The mixture swirls down the outer reactor wall and passes a series of electric heaters that raise the temperature to 850ºC (1,562ºF). The reduction reaction occurs as the gases travel toward the scrubber where hydrogen chloride, heat, water, and particulates partition out.

Gas-phase chemical reduction is suitable for the treatment of PCBs, dioxins, and chlorinated solvents. Demonstration tests were performed on wastewater containing an average PCB concentration of 4,600 parts per million and waste oil containing an average of 24.5 percent PCBs. Destructive removal efficiencies of 99.9999 percent were attained during the test runs that were conducted for the EPA's Superfund Innovative Treatment Evaluation Demonstration Program at a Toxic Substances Control Act/RCRA permitted landfill (EPA 1993).

D.4.5 NITRATE TO AMMONIA AND CERAMIC PROCESS

The nitrate to ammonia and ceramic process is used to destroy nitrates present in aqueous, mixed wastes. The process products are an insoluble ceramic waste form and ammonia, which can be further processed through a catalyst bed to produce nitrogen and water vapor. This technology includes a low-temperature process for the reduction of nitrate to ammonia gas in a stirred ethylene glycol-cooled reactor. The process uses an active aluminum (from commercial or scrap sources) to convert nitrate to ammonia gas with the liberation of heat. Silica is added to the reactor, depending on the sodium content of the waste. The aluminum-silica-based solids precipitate to the bottom of the reactor and are further processed by dewatering, calcination, pressing, and sintering into a ceramic waste form. The process results in a 70 percent volume reduction; however, the process is highly exothermic, so safety controls are required, and an inert gas is required to prevent a potential explosive reaction between the ammonia and hydrogen produced in the reactor.

Bench-top experiments at the Hanford Site have confirmed that the nitrate to ammonia and ceramic process will reduce the nitrate present in aqueous waste to ammonia and hydrated alumina. When silica is added, the reactor product can be used to produce an alumina-silica-based ceramic. Bench-top experiments also demonstrated process dependence on feed constituents and reaction rates. Determination of properties of the waste, such as leachability, is continuing (DOE 1994b).

D.4.6 RESORCINOL-FORMALDEHYDE ION EXCHANGE RESIN

Resorcinol-formaldehyde ion exchange resin beds can be used to remove ionic radionuclides (such as cesium) from high-level radioactive supernatant at 10 times the capacity of baseline phenol-formaldehyde resin beds. Resorcinol-formaldehyde ion exchange resin technology is applicable to highlevel wastes that contain high-alkalinity, cesium-supernatant salt solutions. The cesium in the waste is the result of reprocessing spent nuclear power reactor fuels. High-level waste supernatant can be processed through ion exchange columns where cesium undergoes selective sorption in the resorcinol-formaldehyde ion exchange resin and is effectively removed from the waste. After the columns become saturated, they can be removed from service so the cesium can be eluted from the resin with acid. The concentrated cesium can be sent for vitrification, while the regenerated column can be returned to service. The high-level radioactive supernatant that was originally sent through the ion exchange columns can then be stabilized. Spent exhausted resin can be rigorously eluted to lower its cesium content, followed by incineration or chemical destruction. Resorcinol-formaldehyde ion exchange resin has 10 times the capacity of baseline resins, and no volatile organic compounds are formed from radiolysis; however, offgas treatment may be necessary due to the formation of small quantities of hydrogen gas. This technology is fairly limited in its application. Additional contaminants, such as actinides, strontium-90, and mercury must be removed prior to stabilization of the supernatant.

Bench-scale testing has shown that resorcinol-formaldehyde ion exchange resin appears useful over a wide range of concentrations and temperatures. A system prototype is being developed for demonstration at the Hanford Site (DOE 1994a).

D.4.7 SUPERCRITICAL WATER OXIDATION

Supercritical water oxidation is an aqueous-phase oxidation treatment for organic wastes in which organic waste, water, and an oxidant (such as air or oxygen) are combined in a tubular reactor at temperatures and pressures above the critical point of water. The organic constituents are reduced to water, carbon dioxide, and various biodegradable acids. The process occurs above the critical point of water because the water in the liquid waste becomes an excellent solvent for the organic materials contained in the waste.

Supercritical water oxidation is a closed loop system with very small secondary waste generation. Although this process occurs at mild temperatures [400 to 650ºC (752 to 1,202ºF)] compared to incineration [1,000 to 1,200ºC (1,832 to 2,191ºF)], the high pressure creates a need for additional process containment, especially when treating radioactive waste. The process is limited to dilute liquid wastes and has not been demonstrated on solid wastes. This treatment method has been tested with a bench-scale system, using cutting oil containing a simulated radionuclide. During bench-scale testing, oxidation efficiencies greater than 99.99 percent were achieved; however, the resulting solid effluent contained levels of the simulated radionuclide that suggest that actual treatment effluent would require further treatment as a radiological hazard. DOE has completed benchscale testing using mixed waste surrogates, and has begun designing the hazardous waste pilot plant. The hazardous waste pilot plant will be used to identify additional technology needs and to demonstrate currently available technology using hazardous and surrogate mixed waste (DOE 1993, 1994c).

D.4.8 WET AIR OXIDATION

The wet air oxidation process is a treatment method used to destroy organic contaminants in liquid waste streams. Oxidizing organic substances can degrade them into carbon dioxide and water. The waste is heated and passed, along with compressed air, into the oxidation reactor where the chemical reactions take place.

Commercially available wet air oxidation methods are limited to treating dilute (less than 10 percent by weight organics) liquid wastes; however, the addition of a metal catalyst can drastically alter the treatability of the waste. A metal catalyst may allow degradation of halogenated aromatic compounds (such as PCBs) and condensed-ring compounds. A method that uses a metal catalyst to assist in the waste treatment process is currently being bench-scale tested for hazardous, radioactive, and mixed wastes. This method has been successful in treating liquid wastes as well as solid wastes. The benchscale studies have been performed using a batch oxidation reactor and a continuous oxidation reactor; both showing promising results.

The bench-scale tests have proven that sufficient oxidation rates can be achieved using wet oxidation methods with the addition of a metal catalyst. Experiments showed that oxidation rates for organic solids are highly dependent on surface area of the solid and the interfacial contact area in the reaction vessels; therefore, efficient mixing is very important. A scheme has been identified to allow separation of radioactive and toxic metals from the process solution (DOE 1993; Wilks 1989).

D.4.9 WET CHEMICAL OXIDATION (ACID DIGESTION)

Wet chemical oxidation uses nitric acid, air, and a catalyst to oxidize liquid and solid organic wastes. The wet chemical oxidation, or acid digestion, process is currently under investigation at SRS for its applicability for treating hazardous and mixed wastes. An advantage of such a process is that it requires only moderate temperatures and pressures; however, several parameters are still under investigation. Research on operating temperatures and catalyst and oxidant concentrations must be completed before initiating feasibility studies on the various applications. Early experiments, however, showed promising results for treating specific waste types.

Because this technology is still in initial bench-scale development, the applicability of the system to a variety of wastes is difficult to predict. Theoretically, however, this process should be able to successfully treat many hazardous, low-level radioactive, and mixed wastes. The current system could produce large amounts of secondary waste products, such as spent acids, that would require additional treatment (DOE 1993; Apte 1993).

D.4.10 EVAPORATION AND CATALYTIC OXIDATION

The evaporation and catalytic oxidation system treats a variety of hazardous liquid wastes by reducing the waste volume and oxidizing volatile contaminants. The proprietary technology combines evaporation with catalytic oxidation to concentrate and destroy contaminants, producing a nontoxic product condensate. The system consists of (1) an evaporator that reduces the influent volume, (2) a catalytic oxidizer that oxidizes the volatile contaminants in the vapor, (3) a scrubber that removes acid gases produced during oxidation, and (4) a condenser that condenses the vapor leaving the scrubber. The treatment would be most effective on liquid wastes containing mixtures of metals, volatile and nonvolatile organics, volatile inorganics, and radionuclides. The technology destroys contaminants and produces a nontoxic product condensate without using expensive reagents or increasing the volume of the total waste. A pilot-scale facility at the Clemson Technical Center has been developed for treating radioactive, hazardous, and mixed wastes under EPA's Superfund Innovative Treatment Evaluation Demonstration Program. Secondary wastes streams such as evaporator bottoms and sludges would still require disposal. Limitations include potential heavy metal effects on catalysts and a fairly narrow applicability. A commercial system is in operation in Hong Kong (EPA 1993).

D.4.11 BIOCATALYTIC DESTRUCTION

DOE is developing an enzyme-based reactor system to treat aqueous mixed and low-level radioactive wastes that have high nitrate and nitrite concentrations. The process involves the use of both electrical potential and enzymes to convert the nitrates and nitrites to nitrogen and water. The use of enzymes generates large specific catalytic activity without the need for additional chemical reagents or the production of secondary waste streams.

Removal of nitrates and nitrites from aqueous mixed waste and low-level radioactive waste by the biocatalytic destruction process can be used to pretreat waste in preparation for stabilization by solidification. Laboratory testing, consisting of immobilization of enzymes necessary for reducing nitrates to nitrogen and water, is being conducted by DOE's Argonne National Laboratory (DOE 1994b).

D.4.12 ELECTROCHEMICAL OXIDATION

Electrochemical treatment of hazardous, mixed, and low-level radioactive waste is a direct oxidation process. Oxidation of the organic constituents of the waste can occur in the electrochemical cell through two methods. The process can take place at the cell anode by direct oxidation or with the addition of an oxidizing agent to react with the organics in the cell. This process is limited to the treatment of relatively homogeneous liquid wastes and has been limited to lab-scale demonstrations. Pilotscale and commercial systems are being developed, and large-scale experiments using a commercially available industrial electrochemical cell have been performed at Lawrence Livermore National Laboratory. A bench-scale electrochemical oxidation unit for destroying waste benzene was developed and demonstrated at SRS (Moghissi et al. 1993; DOE 1993).

D.4.13 MEDIATED ELECTROCHEMICAL OXIDATION

Mediated electrochemical oxidation is a method that was originally developed to treat an insoluble form of plutonium, and it later proved to be an effective method to treat combustible materials. The process utilizes a strong oxidizing agent (a form of silver), which chemically destroys combustible materials and converts the waste into carbon dioxide and water. Mediated electrochemical oxidation can effectively dissolve metals, has a very efficient destruction rate, and operates at near-ambient conditions. The process could produce a secondary waste containing a form of silver that would pose disposal problems.

Bench-scale and pilot-scale testing at DOE's Rocky Flats Plant have shown that the mediated electrochemical oxidation process is capable of achieving high destruction efficiencies for selected, nonradioactive surrogate materials (Moghissi et al. 1993).

D.5 Physical Treatment Technologies

Physical treatment methods are diverse and rely on physical properties, such as electromagnetic or particulate radiation, high pressure, or gravity. Innovative physical treatment technologies include the use of sound waves to separate particulates from aqueous-phase liquids, the use of electron beams to treat hazardous organics in groundwater, the use of pressure filters to remove metals and radionuclides, and the use of precipitation following coagulation and chemical binding. Several physical treatment technologies, such as the electron beam and filtration methods, are energy intensive.

D.5.1 ACOUSTIC BARRIER PARTICULATE SEPARATOR

This technology is a treatment method for high-temperature, high-throughput offgas streams. The offgas is injected into the separation chamber where an acoustic wave is produced and directed against the flow of the gas. The acoustic wave causes particulates in the offgas to move opposite the gas flow and toward the chamber wall. There, the particulates collect and precipitate into a collection hopper and are removed from the system. Applications include the separation and removal of particles. The process has the potential for high removal efficiencies at high throughput; however, high temperatures must be maintained for condensation and particulate precipitation. Additional treatment, such as the use of high efficiency particulate air filters, may be necessary for some wastes. A pilot-scale system is currently in the design and construction phase under EPA's Superfund Innovative Treatment Evaluation Emerging Technology Program (EPA 1993).

D.5.2 CHEMICAL BINDING/PRECIPITATION/PHYSICAL SEPARATION OF RADIONUCLIDES

Chemical binding/precipitation/physical separation of radionuclides is an innovative technology used to treat contaminated low-level radioactive and mixed waste water, sludges, and soils. The treatment combines a chemical binding process and a physical separation process. The initial step of the combined treatment process involves rapid mixing of the waste with a fine powder containing reactive binding agents, such as complex oxides. The binding agents react with most of the radionuclides and heavy metals in the waste by absorption, adsorption, or chemisorption. The reactions yield precipitates or coagulum in the processed slurry.

Water is then separated from the solids. This involves a two-stage process that combines clarifier technology, microfiltration (to separate solid material by particle size and density), and dewatering using a sand filter. The resulting waste contains radionuclides, heavy metals, and other solids that can be stabilized for disposal. The demonstrated technology should produce a dewatered sludge that meets toxicity characteristic leaching procedure criteria; however, adding reagents tends to increase the production of waste product. This process may be limited by the quality of the water separated from the solids. Demonstrations under EPA's Superfund Innovative Treatment Evaluation Demonstration Program are expected to show the technology's applicability to wastes containing radium, thorium, uranium, man-made radionuclides, and heavy metals (EPA 1993).

D.5.3 CHEMICAL TReaTMENT AND ULTRAFILTRATION

The chemical treatment and ultrafiltration process is used to remove trace concentrations of dissolved metals from waste water. The process produces a volume-reduced water stream that can be treated ultimately for disposal. Waste water is passed through a prefilter to remove suspended particles. The prefiltered waste water is sent to a conditioning tank for pH adjustment and addition of water-soluble macromolecular compounds that form complexes with heavy metal ions. Next, a polyelectrolyte is added to achieve metal particle enlargement by forming metal-polymer complexes. The chemically treated waste water is circulated through a cross-flow ultrafiltration membrane. The filtered water is drawn off, while the contaminants are recycled through the ultrafiltration membrane until the desired concentration is reached. The concentrated stream can be withdrawn for further treatment, such as solidification. Initial bench and pilot-scale tests were successful; however, field demonstrations at Chalk River Laboratories, Ontario, indicated that pretreatment methods need further evaluation.

DOE is currently considering alternative methods of waste water pretreatment for ultrafiltration, including the use of water-soluble chelating polymers for actinide removal and the use of reagents and polymeric materials that exhibit selectivity for cations of heavy metals. Bench-scale tests have been conducted at DOE's Rocky Flats Plant in collaboration with the EPA's Superfund Innovative Treatment Evaluation Demonstration Program (EPA 1992a).

D.5.4 HeaVY METALS AND RADIONUCLIDE POLISHING FILTER

The heavy metals and radionuclide polishing filter uses a colloidal sorption method to remove ionic colloidal, complexed, and chelated heavy metal radionuclides from waste water streams. This technology must be combined with an oxidation process in order to treat waste water that is also contaminated with hydrocarbons, hazardous organics, or radioactive mixed wastes. This technology consists of a colloidal sorption unit that contains a high-efficiency, inorganic, pressure-controlled filter bed. Pollutants are removed from the waste water via surface sorption and chemical complexing in which trace inorganics, metals, transuranic, and low-level wastes can be efficiently treated. The polishing filter can be used for batch or continuous flow processing. Bench tests at DOE's Rocky Flats Plant were conducted for the removal of uranium-234 and -238, plutonium-239, and americium-241 with successful results; however, a measurable analysis was not possible due to the low activity levels of the radionuclide. Bench-scale testing is being conducted under EPA's Superfund Innovative Treatment Evaluation Demonstration Program in collaboration with DOE's Rocky Flats Plant (EPA 1993).

D.5.5 MEMBRANE MICROFILTRATION

The membrane microfiltration system is designed to remove solid particles from liquid wastes. Specifically, this technology can treat hazardous waste suspensions and process wastewaters containing heavy metals. The system uses an automatic pressure filter with a special Tyvek filter material (Tyvek T980) made of spunbonded olefin. The material is a thin, durable plastic fabric with tiny openings that allow water and smaller particles (less than one-ten-millionth meter in diameter) to pass, while larger particles accumulate on the filter to form a filtercake. The filtercake can be collected for further treatment prior to disposal. This technology is best suited for liquid waste containing less than 5,000 parts per million solids; however, the system is capable of treating wastes containing volatile organics because the system is enclosed. The technology was demonstrated with encouraging results, including removal efficiencies from 99.75 to 99.99 percent and filtercake that passed RCRA toxicity characteristic leaching procedure standards. The technology is being demonstrated under the EPA's Superfund Innovative Treatment Evaluation Demonstration Program at the Palmorton Zinc Superfund Site (EPA 1993).

D.5.6 ELECTRODIALYSIS

This technology is used for metals recovery in aqueous liquid wastes generated in a production process. Electrodialysis uses membrane technology for selective removal of contaminants from a liquid waste. The liquid waste is usually aqueous with contaminants in ionic form. A direct current electrical potential is used to selectively transport the ions through a membrane where the ionic contaminants can be collected for further treatment.

This technology is not appropriate for treating liquid organic wastes; however, recovery of hazardous metals such as cadmium, nickel, zinc, copper, and chromium is possible. Limitations include operating in a batch mode using reagent-grade chemicals. Electrodialysis technology is commercially available and several membrane technologies suitable for use with an electrodialysis system are being developed under EPA's Superfund Innovative Treatment Evaluation Emerging Technology and Demonstration program (Apte 1993; DOE 1993).

D.5.7 FREEZE CRYSTALLIZATION

Freeze crystallization technology is based on differences in the freezing points of waste components. During freeze crystallization, a liquid waste is cooled using a refrigerant. As the phase changes from liquid to solid, crystals of solvent and contaminant solutes form separately. These crystals can then be gravity separated.

Freeze crystallization can be used to treat liquid mixed wastes containing inorganics, organics, heavy metals, and radionuclides in which the freezing temperatures of the various constituents differ significantly. The technology offers some advantages over other processes. For example, the process offers high decontamination and volume reduction factors, it requires no additives, and it operates at low temperatures and pressures, making it intrinsically safe. However, the technology is limited to those wastes that contain contaminants that crystallize easily. This project is being developed for DOE applications and is in the small pilot-scale development and demonstration stage. The technology will be demonstrated at the proprietor's pilot plant in Raleigh, North Carolina (DOE 1994b).

D.5.8 HIGH-ENERGY ELECTRON IRRADIATION

Electron irradiation process equipment consists of an electron accelerator that accelerates a beam of electrons to 95 percent of the speed of light. The beam is directed into a thin stream of waste water or sludge where free radicals are produced to react with the hazardous organics. Although the electron beam is a form of ionizing radiation, the process does not produce activated radioisotopes.

High-energy electron irradiation of aqueous solutions and sludges removes various hazardous organic compounds from aqueous wastes containing 8 percent solids. The process of irradiation produces large quantities of free radicals in the form of aqueous electrons, hydrogen radicals, and hydroxyl radicals. The hydroxyl ions can recombine to form hydrogen peroxide. These very reactive chemical species react with organic contaminants, oxidizing them to nontoxic byproducts, such as carbon dioxide, water, and salts.

Electron irradiation may be suitable for the treatment of halocarbons, aromatics, and nitrates. Disadvantages of this process include high power requirements and interferences from solids. The process produces low concentrations of aldehydes and formic acid; however, at these concentrations those compounds are not toxic. Both a full-scale facility and a mobile demonstration unit have been developed. The process is currently being demonstrated for the treatment of volatile organic compounds at SRS through EPA's Superfund Innovative Treatment Evaluation Demonstration Program. In addition, DOE's Los Alamos National Laboratory is evaluating the suitability of electron irradiation for treating aqueous mixed wastes and sludges contaminated with organics and nitrates (DOE 1994b; EPA 1993, 1994).

D.5.9 ULTRAVIOLET OXIDATION

Ultraviolet oxidation uses ultraviolet radiation, ozone, and hydrogen peroxide to destroy toxic organic compounds in water. Ultraviolet oxidation is a common treatment for industrial and municipal waste water. Although commercial systems are available for dilute waste forms, destruction of high organic concentrations requires additional oxidizing agents, such as ozone and hydrogen peroxide. Ultraviolet radiation breaks down the hydrogen peroxide to products that chemically convert organic materials into carbon dioxide and water. This technology operates at near-ambient conditions and generates a very small amount of secondary waste but operates at a slower destruction rate than other technologies. System demonstrations with contaminated groundwater met regulatory standards for volatile organic compounds.

Pilot-scale demonstrations were completed under the EPA's Superfund Innovative Treatment Evaluation Demonstration Program. The technology is fully commercial and is used by various industries as well as DOE for site cleanup activities. The units operate at waste flow rates ranging from 5 to 1,050 gallons per minute (EPA 1993).

D.5.10 PRESSURE WASHING AND HYDRAULIC JETTING

Pressure washing and hydraulic jetting decontamination techniques effectively remove surface contamination from solid materials. These techniques are applicable for decontamination of equipment and in the recovery of reusable or recyclable materials.

Pressure washing consists of a combination of pressurized water washing and chemical cleaning. During pressure washing, an alkaline solvent is used to remove the surface oxide, and an acidic solvent is used to dissolve any remaining residue. Liquid wastes produced from this process can be concentrated into a sludge waste form for further treatment.

The hydraulic jetting process uses a high-pressure hydrolaser to remove surface contaminants. An abrasive additive can be used to remove more persistent contaminants. This process produces a secondary liquid waste that requires further treatment by solidification.

SRS plans to demonstrate washing and jetting technologies for the treatment of low-level lead shielding. The decontaminated lead shielding can be released for reuse, while the process liquid wastes would be concentrated and solidified into a waste form that meets toxicity characteristic leaching procedure standards (Scientific Ecology Group, Inc. 1993).

D.5.11 SOIL-WASHING

Soil-washing consists of deagglomeration, density separation, particle-sizing, and water-rinsing of contaminated soils. Process water can be containerized, recirculated, and treated to remove suspended and dissolved contaminants. Soil washing technologies are being tested using bench-scale commercial equipment to provide equipment costs and operating estimates. Experiments are also being conducted to develop secondary soil treatment technologies that reduce contaminant levels below the levels already achievable with standard attrition, extraction, and leaching procedures.

The soil-washing process has been used to separate uranium from soil at the Fernald Environmental Management Project. The multi-phase soil-washing process begins with a soil and leachate mixture, which is fed into an attrition scrubber to solubilize the uranium from the soil. Next, the mixture flows into a mineral jig where fine uranium particles and contaminated solutions are separated from the soil. The contaminated materials overflow from the jig while the clean soils exit from the bottom. The bottom soils are then screened and washed to remove any uranium residuals. The overflow slurry is collected for appropriate disposal. The bench-scale unit can treat both solid and liquid wastes. Each waste form, however, must be fed into the attrition scrubber separately. Limitations of this technology include handling and disposal of secondary wastes. A bench-scale soil-washing demonstration is being planned at SRS, and several demonstrations are being conducted by the EPA's Superfund Innovative Treatment Evaluation Demonstration Program (EPA 1993).

D.5.12 STeaM REFORMING

Steam reforming consists of a waste evaporation system in which liquid or slurried low-level radioactive and mixed wastes are gasified by exposure to super-heated steam. The gasified organic materials are sent to an electrically heated detoxification reactor where they are converted to nontoxic vapors by thermal decomposition. The detoxified gases are then fed to adsorber beds to remove trace organics, metals, and halogens and are oxidized to carbon dioxide and water and vented to the atmosphere. Steam reforming is currently being tested for its applicability to mixed wastes and may prove to be a viable alternative to incineration. A current project includes demonstration tests corroborated by Sandia National Laboratories and Synthetica Technologies. The project focuses on destruction of organics, nitrate decomposition, and mercury processing and uses a commercial steam reforming unit. Commercial steam reforming has been shown to destroy most of the organic solvents and polymeric organics commonly found in mixed wastes.

A commercial steam reforming unit, the synthetic detoxifier, is currently being tested at SRS. The SRS system has produced destruction and removal efficiencies greater than 99.9 percent for simulated benzene wastes; however, carbon formations caused prohibitive pressure drops in the system. The current acceptable waste is limited to low-heating-value organics because of carbon limitations. Waste acceptance may also be limited to aqueous liquids and small, dry, heterogeneous solids (DOE 1993, 1994a, b).

D.6 Stabilization Technologies

Stabilization and solidification treatment methods are used to immobilize radionuclides and other hazardous inorganic compounds (such as heavy metals) using matrices (such as low sulfur cement or other grouting compounds, polyethylene and other thermoplastics, or bitumen). Stabilization and solidification can effectively immobilize wastes, and costs are lower than other methods, such as vitrification and plasma arc technologies. The primary disadvantage is that waste volumes are increased by the addition of the binding agent. Also, the final waste form is not as leach-resistant as glass or slag. Although cement can result in an effective stabilization matrix, a lack of effective process and quality controls can cause major problems (e.g., failure to cure properly). Both the Oak Ridge Reservation and the Rocky Flats Plant experienced incidents when mixtures of waste and cement failed to cure properly.

At SRS, liquid low-level radioactive waste is currently being stabilized in a grout matrix at the Saltstone Facility. Stabilization is also being considered at SRS for wastes (such as ash and blowdown) from the Consolidated Incineration Facility.

D.6.1 POLYETHYLENE ENCAPSULATION

High-level and low-level mixed wastes containing heavy metals and chloride salts that cannot be stabilized by incineration or vitrification may be incorporated into the polyethylene encapsulation system. Encapsulation technologies provide a physical matrix to stabilize wastes, and are generally not affected by chemical reactions with the waste. Polymeric encapsulation can be used to stabilize a variety of wastes, including incinerator ash, sludges, aqueous concentrates, dry solids, and ion exchange resins. The result is a final waste form that exhibits extremely low leachability characteristics. During polyethylene encapsulation, the pretreated waste, binder, and additives are precisely metered and volumetrically fed to a polyethylene single-screw extruder, which produces the final waste form. Optimization of the polymer matrix is achieved by adjusting density, molecular weight, and melt index. The process extrudes a molten, homogeneous mixture of waste and polyethylene binder into a suitable mold. A transient infrared spectrometer system is used to confirm waste loading.

The technology was successfully applied to the treatment of hazardous and mixed wastes, such as sodium nitrate salt and sludges. Limitations include potential matrix effects by wastes containing excess water, potential biological reactions, potential hydrogen gas generation, and potential fire hazards in closed spaces. Recently, a full-scale demonstration was successfully completed at Brookhaven National Laboratory (DOE 1994b).

D.6.2 POZZOLANIC SOLIDIFICATION AND STABILIZATION

Pozzolanic solidification and stabilization is a technology used to treat soils, sludges, and liquid wastes that are contaminated with organics and metal-bearing wastes. The technology uses a proprietary reagent that chemically bonds with contaminants in the waste. The waste and reagent mixture is combined with a pozzolanic cement mixture to form a stable matrix. Prior to processing, the waste must be characterized for treatability to determine the type and quantities of reagents used in the process. The process begins with waste material sizing during which large debris is removed from the waste. The waste is mixed with the proprietary reagent in a high-shear mixer; then pozzolanic, cementitious materials are added. Limitations include potential setup problems with the waste and reagent mixtures. The technology has been commercially applied to treat wastes contaminated with organics and mixed wastes, and DOE's Brookhaven National Laboratory is continuing testing and demonstration of solidification technologies (EPA 1993).

D.6.3 VINYL ESTER STYRENE SOLIDIFICATION

Vinyl ester styrene solidification has been demonstrated commercially for the emulsification of ion exchange resins. The binder is pulled down through the resin packing bed with a vacuum, and the binder is allowed to solidify into a matrix that will pass toxicity characteristic leaching procedure testing. The emulsified waste forms have been accepted for burial at various sites, and DOE's Hanford Site has recently approved a vinyl ester waste form for inclusion on the Waste Form Acceptance List. DOE plans to demonstrate the viability of vinyl ester styrene solidification for low-level silver-coated packing material (Diversified Technologies 1993).

D.7 Thermal Treatment Technologies

Thermal treatment technologies use moderate or high temperatures to vaporize organics or high temperatures to convert organic waste constituents primarily to carbon dioxide and water vapor. Inorganic waste constituents (such as heavy metals and radionuclides) are concentrated into secondary wastes (such as ash, slag, glass, or blowdown) or captured in offgas treatment systems (such as high-efficiency particulate air filters or baghouses). Some volatile compounds are emitted through the stack. Removal efficiencies for metals are dependent on the chemical and thermodynamic properties of the element or compound. Mercury and cesium are considered volatile metals. Incineration technologies (such as rotary kilns and controlled air systems) have been used traditionally to destroy the organic portion of hazardous wastes, and incineration is the EPA-specified best demonstrated available technology for many hazardous organics (such as solvents and PCBs).

Alternatives to conventional incineration methods are being considered for treating wastes containing metals and radionuclides, including alpha-contaminated and transuranic wastes. Innovative technologies for these types of wastes include vitrification (which immobilizes inorganic contaminants in a glass matrix), plasma arc technology (which uses extremely high temperatures to produce a molten slag), and molten salt oxidation (which oxidizes organics into a molten salt solution). Vitrification and plasma arc technologies generally require secondary combustion chambers to destroy hazardous organics. These technologies have the advantage of producing final waste forms that are extremely leach-resistant, with very small environmental effects following final disposal. Disadvantages include high costs of startup and operation. In some cases, a combination of conventional and innovative technologies can be appropriate, such as vitrifying radionuclide-contaminated ash from a conventional incinerator.

DOE is supporting two full-scale vitrification projects at SRS: (1) the Defense Waste Processing Facility, a joule-heated melter which will be used to vitrify high level wastes, and (2) the M-Area Vendor Treatment Facility, which will be used to vitrify electroplating sludges contaminated with radionuclides. Research and development projects related to vitrification are ongoing at SRS, universities (such as Clemson University), and other outside facilities. Plasma arc technology is being demonstrated at the Idaho National Engineering Laboratory, where soils and metals contaminated with transuranic radionuclides will be converted into a glassy slag. Studies related to molten salt oxidation are ongoing at Lawrence Livermore National Laboratory.

At SRS, thermal treatment technologies would be effective in reducing the volume of solid low-level radioactive waste, such as job-control waste, prior to final disposal. Alternative technologies (such as vitrification and plasma arc technology) would be effective in treating and stabilizing other waste forms (such as liquids and sludges and metal-bearing wastes).

D.7.1 FLAME ReaCTOR

The flame reactor is a patented, hydrocarbon-fueled, flash-smelting system that treats residues and wastes that contain metals. The reactor operates at temperatures exceeding 2,000 °C, at a capacity of 1 to 3 tons per hour. The wastes are processed with reducing gas that is produced by the combustion of solid or gaseous hydrocarbon fuels. Volatile metals are captured in a product dust collection system, while nonvolatile metals are separated as a molten alloy or encapsulated in the slag. Organic compounds are destroyed by thermal decomposition.

The unit has a high waste throughput; however, the wastes must be dry and fine enough that the reducing reaction can occur rapidly or efficiency of metal recovery is decreased. The flame reactor technology is applicable to specific waste forms, such as granular solids, soil, flue dusts, slag, and sludges containing heavy metals. The end products are a glass-like slag that passes the toxicity characterization leaching procedure criteria and a potentially recyclable heavy metal oxide. The technology is being developed under the EPA's Superfund Innovative Treatment Evaluation Demonstration Program (EPA 1992a, b, 1993).

D.7.2 THERMAL DESORPTION PROCESS

The thermal desorption process is a low-temperature thermal and physical separation process designed to separate organic contaminants from soils, sludges, and other media without decomposition. Contaminated solids are fed into an externally heated rotary dryer where temperatures range from 400 to 500 °C. A recirculatory inert carrier gas that is maintained at less than 4 percent oxygen to prevent combustion is used to transport volatilized contaminants from the dryer. Solids leaving the dryer are -sprayed with cooling water to help reduce dusting. The inert carrier gas is treated to remove and recover particulates, organic vapors, and water vapors. Organic vapors are condensed and treated separately; water is treated by carbon adsorption and used to cool and reduce dusting from treated solids or is discharged.

A full-scale system is being used to treat soils contaminated with PCBs. The system can treat up to 240 tons of soil per day and reduce it to a concentration of less than 2 parts per million. Two laboratoryscale systems are being used to treat hazardous and mixed wastes. A 7-ton-per-day soil treatment pilot-scale facility is also being used to treat different types of PCB contaminated soils under the EPA's Superfund Innovative Treatment Evaluation Demonstration Program.

The technology advantages include low temperature operation and treatment levels below 1 part per million. Disadvantages include concentrations of extremely hazardous organic compounds, generation of incomplete combustion products (such as dioxin), and the need to transport and/or treat recovered organic liquids (EPA 1993).

D.7.3 UNVENTED THERMAL PROCESS

The unvented thermal process is a high-temperature treatment process that destroys organic contaminants without releasing gaseous combustion products to the environment. The primary treatment unit is a fluidized-bed processor. The processor contains a bed of calcined limestone, which reacts with the offgases produced during the oxidation of organic constituents in the waste. Such gases include carbon dioxide, sulfur dioxide, and hydrogen dioxide. The resulting water vapor is collected and removed through a condenser, and the remaining gases (mostly nitrogen) are mixed with oxygen and returned to the oxidizer. The spent resin from the fluidized bed can then be treated and stabilized.

This process does not release gas from the system and so could attain better public acceptance than conventional thermal treatment technologies. Remaining hazardous byproducts would be mixed with cement-making materials to form a solid cement.

The unvented system favors certain types of wastes, depending on the availability of oxygen and emission limits. Potential wastes include those containing chlorinated hydrocarbons, solid and liquid mixed wastes, and hospital wastes. Mixed waste treatment is suited to the unvented system because it prevents radionuclide emissions.

The unvented thermal process for treating mixed wastes is under development at Argonne National Laboratories. The laboratory-scale experiments have not been completed. Work remains on sorption kinetics and recyclability of the limestone bed as well as verification of total organic destruction. The unvented thermal process could be viable for future use (International Incineration Conference 1993; DOE 1993).

D.7.4 MOLTEN SALT OXIDATION AND DESTRUCTION PROCESS

The molten salt oxidation and destruction process is a two-stage process for treating hazardous and mixed wastes by destroying the organic constituent of the waste. The treatment method involves injection of the waste into a molten bed of salt (specifically, a mixture of sodium-, potassium-, and lithium-carbonates). This pyrolysis stage is designed to operate at between 700 and 950 °C depending on the type of salt and the ash content of the waste. Oxidation occurs in the molten-salt bed because of the injection of an oxidizing gas (such as air) into the waste and molten salt mixture. This oxidation stage can occur at greater than 700 °C, if necessary. Heteroatom constituents of the waste (such as sodium chloride) are retained in the melt. Radioactive actinides are also retained in the melt. The lower operating temperature of this process (compared to incineration at 1,000 to 1,200 °C) decreases actinide volatilization. At the end of a run, the molten salt is drained out of the reactor and dissolved in water. The oxides and stable salts of the actinides precipitate and are filtered out for disposal as low-level radioactive or hazardous waste.

Treatable wastes that are appropriate for this method include organic liquids containing chlorinated solvents and PCBs, combustible low-ash solids, organic sludges, explosives, chemical warfare agents, rubbers, and plastics. Process uncertainties that must be resolved include the effects of ash and stable salt buildup on melt stability and spent salt processing, retention of particulates in the molten salt bed, and the process's tolerance to variations in operating conditions.

Although this system is not commercially available, it does exist as a pilot-scale project at the Lawrence Livermore National Laboratory. A conceptual design report for a full-scale demonstration facility has been issued. Construction is expected to start in 1996 (Moghissi et al. 1993; DOE 1993).

D.7.5 QUANTUM-CATALYTIC EXTRACTION PROCESS

The quantum-catalytic extraction process is a proprietary technology that allows organic and inorganic wastes to be recycled into useful resources of commercial value. The process involves the destruction of hazardous components and controlled partitioning of radionuclides into a solid, nonleachable waste form. The technology consists of a molten metal bath that acts as a catalyst and a solvent that breaks the molecular bonds of the waste compounds. Upon introduction into the molten metal bath, the waste dissociates into its constituent elements and goes into metal solution. Once the constituent elements are dissolved, proprietary co-reactants are added to enable reformation and partitioning of desired products. The catalytic processing unit (the reactor that holds the molten metal bath) can handle most waste forms, including gases, pumpable liquids and slurries, fine solids, and bulk solids. The process is also equipped with an offgas system and allows injection of co-feeds (such as oxygen) to enhance oxidation of radioactive components.

Bench-scale experiments were conducted using surrogate radioactive materials to demonstrate the oxidation and partitioning of the radionuclides between the metal and vitreous phases and to optimize operating conditions. Decontamination of the metal was greater than 99 percent, and detection of trace amounts of surrogate radionuclides was limited by the analytical detection limit. The quantum-catalytic extraction process is currently being bench-tested to demonstrate ion exchange resin processing capabilities.

Technology development and demonstration efforts are being conducted under a DOE Planned Research and Development Agreement. The scope of work includes theoretical design of quantum-catalytic extraction process systems, radionuclide partitioning, optimization of the vitreous phase for stabilization of radionuclides, testing of waste regulated by RCRA, and conceptual design and development for treatment and recycling of heavily contaminated scrap metal.

A demonstration facility is under development at DOE's Oak Ridge Reservation. The demonstration facility targets the disposal of mixed waste that is regulated under RCRA land disposal restrictions and the Federal Facilities Compliance Act (Herbst et al. 1994; DOE 1994b).

D.7.6 INFRARED THERMAL DESTRUCTION

Infrared thermal destruction uses electrically powered silicon carbide rods to heat organic wastes to combustion temperatures. Any remaining combustibles must be incinerated in an afterburner. The technology is suitable for treating soils and sediments with organic contaminants and liquid wastes after pre-mixing with sand or soil.

The process consists of three components: (1) an electric-powered infrared primary chamber, (2) a gasfired secondary combustion chamber, and (3) an emissions control system. Waste is fed to the primary chamber where it is heated to 1,000°C by exposure to infrared radiant heat. A blower delivers air to the chamber to control the oxidation rate of the waste feed. Ash material from the primary chamber is quenched and conveyed to a hopper for later sampling and subsequent disposal. Volatile gases from the primary chamber flow to the secondary chamber where they undergo further oxidation at higher temperatures and a longer residence time. Gases from the secondary chamber are sent through an emissions control system for particulate separation and neutralization.

The system is capable of high throughput, but at a cost of high-power consumption. Process uncertainties requiring resolution include emission control system inefficiencies and retention of lead in the incinerated ash. Demonstrations have shown that the process should be capable of meeting RCRA and Toxic Substances Control Act standards for particulate and air emissions and PCB remediation.

Two evaluations of the infrared thermal destruction system were conducted under EPA's Superfund Innovative Treatment Evaluation Demonstration Program. Organics, PCBs, and metals were the target waste compounds during the full-scale demonstration at the Peak Oil Site in Tampa, Florida, and a pilot-scale demonstration at the Rose Township Demode Road Superfund Site in Michigan (EPA 1993).

D.7.7 PLASMA HeaRTH PROCESS

Plasma technologies use a flowing gas between two electrodes to stabilize an electrical discharge, or arc. As an electric current flows through the plasma, energy is dissipated in the form of heat and light, resulting in joule heating of the process materials, forming a leach-resistant slag that can be modified by adding such materials as soil. The plasma hearth process relies on a stationary, refractory-lined primary chamber to produce and contain the high temperatures necessary for producing the slag.

The plasma hearth process begins when the waste, either solid or liquid, is fed into the primary plasma chamber where the heat from the plasma torch allows the organic compounds in the waste to be volatilized, oxidized, pyrolyzed, or decomposed. The remaining inorganic material is then fed to the secondary combustion chamber for high-temperature melting, producing a molten slag. Cooling and solidification of the slag provide a nonleachable high-integrity waste form. Offgas volumes are lower than those from conventional incineration units.

The plasma hearth process has undergone bench-scale testing by DOE at Argonne National Laboratories West and is currently undergoing demonstration-scale testing at Ukiah, California, to evaluate potential treatment of solid mixed wastes.

Advantages of plasma technologies include the ability to feed high amounts of metal-bearing wastes, including whole drums. The resulting slag requires no additional stabilization. The technology is extremely robust and can accept waste forms, including papers, plastics, metals, soils, liquids, and sludges. Based on these characteristics, very small characterization data are needed. In non-plasma vitrification technologies, combustion of the paper and plastics can produce soot and result in offgas problems (unless a primary burner is placed upstream of the vitrification unit).

A proof-of-principle demonstration has established the process's ability to treat a wide range of waste types in a single processing step that results in a final vitrified form. Ongoing projects for the plasma hearth process involve major hardware development and the determination of the level of characterization required of mixed waste prior to processing. The plasma hearth process is being developed at DOE's Idaho National Engineering Laboratory (International Incineration Conference 1994; DOE 1994b).

D.7.8 PLASMA ARC CENTRIFUGAL TReaTMENT

The plasma arc centrifugal treatment furnace uses the plasma arc process with an internal rotating drum to treat hazardous, mixed, and transuranic wastes. In this process, the waste is fed into a molten bath (1,650 °C) created by a plasma arc torch. The feed material and molten slag are held in the primary chamber by centrifugal force. Within the plasma furnace, all water and organic waste material are volatilized. The organic material is also fully oxidized to carbon dioxide, water vapor, and acid gases, including sulfur dioxide and hydrochloric acid vapor.

Offgas is then treated by conventional treatment methods. Offgas streams pass through a wet filter to remove heat, humidity, and dust. Next, the offgas is treated in a caustic wet scrubber to remove sulfur oxides and halogen acids, a catalyst bed oxidizes nitric acid to nitrogen dioxide, and a catalytic wet scrubber removes nitrogen dioxide from the offgas. Finally, the cleansed gas stream passes through charcoal and high efficiency particulate air filters before being exhausted to the atmosphere. Nonvolatile waste material is fully oxidized and uniformly melted by the high-power electric arc and collected as molten slag which is then discharged as a nonleachable homogeneous glassy residue. The centrifugal action of the furnace keeps the slag toward the inner walls of the furnace until the rotation is slowed, which allows the slag to move toward the center. The slag then drains from the center of the furnace and is collected in a mold or a drum and allowed to cool and solidify.

This technology has been demonstrated to be applicable for the treatment of various waste types and forms, including hazardous, mixed, and transuranic wastes containing heavy metals and organic contaminants. Demonstration results showed a minimum destructive removal efficiency greater than 99.99 percent, organic and inorganic material concentrations that met toxicity concentration leaching procedure standards, and offgas treatment that exceeded regulatory standards.

A full-scale demonstration of this process is being planned for the Idaho National Engineering Laboratory to remediate soils and debris contaminated with transuranic radionuclides.

SRS has plans to demonstrate a small-scale arc melter vitrification system that would meet all regulatory low-level mixed waste disposal requirements. The system provided will be used to establish operating costs and offgas/secondary waste characteristics for further evaluation and analysis. The operating temperatures of the plasma arc system are expected to allow a variety of low-level mixed wastes to be vitrified in a way that minimizes secondary waste generation and allows regulatory approved disposal of the resulting glassy slag (Feizollahi and Shropshire 1994; International Incineration Conference 1993, 1994; DOE 1993; EPA 1993, 1992c).

D.7.9 GRAPHITE ELECTRODE DC ARC FURNACE

The graphite electrode DC arc furnace has been demonstrated to be a useful alternative in processing lowlevel radioactive and mixed wastes that contain a high-weight-fraction of metals. The graphite electrode DC arc delivers thermal energy, using an arc of ionized gas (plasma), that is developed between two electrodes attached to the material being processed. Temperatures in excess of 1,700 °C are generated by the process, which causes the soil and metal mixture to be stratified into a metal phase, a glass phase, and a gas phase. The final metal and glass waste forms are highly densified. The high temperatures in the vicinity of the DC arc also serve to destroy organics, which results in greatly reduced offgas production relative to combustion treatments. A bench-scale furnace was successfully demonstrated for the DOE's Pacific Northwest Laboratory using a variety of soil mixtures containing metals, combustibles, sludges, and high-vapor-pressure metals. A pilot-scale furnace has been constructed, which includes provisions for containing alpha-emitting radionuclides, continuous waste processing, and the capability to separate the glass phase from the metal phase. Process uncertainties that evolved from the bench-scale testing include graphite electrode consumption and offgas system operations (International Incineration Conference 1993; DOE 1993).

D.7.10 PACKED BED ReaCTOR/SILENT DISCHARGE PLASMA APPARATUS

The packed bed reactor/silent discharge plasma apparatus is a two-stage oxidation system for destroying hazardous liquid wastes. The system may also be applicable for the destruction of PCB contaminated mixed waste. The treatment method combines a thermal oxidation process in an excess air stream and a process to destroy the organic constituents from the reactor exhaust. The packed bed reactor provides thermal oxidation, and the silent discharge plasma unit provides the organic destruction. The plasma unit is operated at ambient temperature and pressure.

Most hazardous waste destruction occurs in the packed bed reactor by heat provided externally (that is, without an open flame). The reactor exhaust is treated in a cold plasma that is generated by electrical discharges in the silent discharge plasma unit. The contents of the plasma include hydroxide and phosphite radicals that react with the organics in the exhaust.

Uncertainties encountered during recent bench-scale tests include the proper packed bed reactor construction materials to resist corrosion and a silent discharge plasma dielectric that is capable of increased reactor exhaust flow.

Bench-scale tests have predicted a destruction removal efficiency greater than 99.9 percent for PCBs using this combined system for treating liquid waste. The production of hydroxide gas through the oxidation process could, however, cause severe corrosion problems if the current system is operated for an extended period of time. This could also produce a secondary waste containing corrosion byproducts contaminated with other potential waste constituents, such as tritium. Changes to the current system to help alleviate these problems are being studied at SRS's soil vapor extraction installation and Los Alamos National Laboratory (International Incineration Conference 1994).

D.7.11 ELECTRIC MELTER VITRIFICATION

Vitrification processes convert contaminated materials into oxide glasses. Suitable feed materials include frit, soils, sediments, and sludges. One vitrification process uses an electric melter to generate the heat needed to create molten glass; this is currently under development for pilot-scale tests. The melter is being evaluated on its ability to determine offgas composition, and to treat wastes using glass compositions that are tailored to the particular type of waste being treated.

In an electric melter, the glass can be kept molten through joule heating because the molten glass is an ionic conductor of relatively high electrical resistivity. As waste is fed into the vitrification unit from the top, the molten glass phase in the center of the unit heats the cold feed. Such a unit has a thick layer of cold feed product on top of the molten glass, which acts as a counter-flow scrubber that limits volatile emissions. This is an advantage over the exposed molten glass surfaces of fossil fuel melters.

The electric melter is expected to treat hazardous, mixed, and low-level radioactive wastes that have lower emissions of toxic offgases than conventional vitrification fossil fuel melters. The Defense Waste Processing Facility at SRS is a full-scale, joule-heated, vitrification unit that will immobilize high-level waste within a stable borosilicate glass matrix. An electric melter for vitrifying nonradioactive, hazardous wastes is being developed under the EPA's Superfund Innovative Treatment Evaluation Emerging Technology Program (EPA 1992d, 1993).

D.7.12 STIRRED MELTER VITRIFICATION

The Savannah River Technology Center has tested the application of a newly developed stirred tank melter for treatment and vitrification of mixed and low-level radioactive wastes (i.e., cesium-contaminated ion exchange resins). Two major problems in existing ion exchange resin melters led to the new technology development. First, the resins had a tendency to form a crust on the surface of the melt, allowing the cesium more opportunity to volatilize due to the increased time needed for the waste feed to be incorporated into the melt. Second, the organic resin caused significant reducing conditions in the melt which could increase the volatility of alkali metals (such as cesium) and affect glass quality.

The stirred melter could eliminate these problems. Because the melter is equipped with an impeller to agitate the melt, the crust formation could be reduced by continuous mixing and drawing of the surface into the melt. Increased oxygen exchange between the melt and the vapors above the surface of the melt could also reduce the negative effects of a reduced melt and could lower the amount of volatilized cesium and alkali metals.

Test results from a study conducted by Clemson University, in collaboration with DOE, show that vitrification of ion exchange resins, mixed, and low-level wastes in a stirred tank melter is operationally feasible (International Incineration Conference 1993, 1994; Moghissi and Benda 1991).

D.7.13 MODULAR VITRIFICATION

The modular vitrification technology is a vitrification process developed to stabilize mixed and low-level radioactive waste.

The system is composed of several stages to treat the various waste forms. First, aqueous wastes, sludges, and slurries enter an evaporator to eliminate excess water from the waste feed. Next the dried solids from the evaporator as well as other solids enter a two-section melter. The upper section, a gasification plenum, contains the solid waste, which feeds the lower section. In the lower cold-wall crucible, molten glass supplies heat to evaporate residual water from the waste and gasifies the organic constituents. The heat also melts the inorganic components, which dissolve into the glass matrix.

Next, vitrified waste is formed and allowed to cool into solidified glass marbles. The marble form is used because of its convenience in handling, sampling, and annealing. Molten liquid metals are also tapped from the crucible and formed into metal cubes. Offgases are treated using conventional methods. Additional testing is necessary to verify system design parameters and to ensure compliance with all air emissions and other regulatory requirements.

Applicable waste forms for the modular vitrification system include dry active wastes, ion exchange resins, inorganic sludges and slurries, and mixed wastes. Full-scale testing and commercial operation of the system by VECTRA Technologies and Batelle Memorial Institute are expected in 1995 (Mason, no date; EPA 1992d).

D.7.14 VORTEC PROCESS

The vortec process is an oxidation and vitrification process for the remediation of soils, sediments, and sludges that are contaminated with organics and heavy metals. In the first step of the process, the slurried waste stream is introduced into a vertical vortex precombustor where water is vaporized, and the oxidation of organics is initiated. The waste stream is then fed to a counter-rotating vortex combustor, which provides suspension heating of the waste and secondary combustion of volatiles emitted from the precombustor. The preheated solid materials are delivered to a cyclone melter where they are separated to the chamber walls to form a vitrified waste product. The vitrified product and process exhaust gases are separated; after which, the exhaust gases are sent to process heat recovery and pollution control subsystems. The advantages of the vortec process include the ability to process waste contaminated with organics and heavy metals, recycle the pollution-control-system waste, and provide a vitrified product that passes toxicity characterization leaching procedure standards. A 20-ton-per-day, pilot-scale facility, located at an EPA-funded site, has operated successfully since 1988, producing a vitrified product that passes toxicity characterization leaching procedure standards. Transport systems are currently being designed for the treatment of DOE mixed wastes (EPA 1993).

D.7.15 IN SITU SOIL VITRIFICATION

In situ soil vitrification uses an electric current to melt and stabilize inorganic waste components while destroying organic waste components by pyrolysis. The process begins by inserting an array of electrodes into the ground. A starter path for electrical current is provided by placing flaked graphite and frit on the ground surface between the electrodes (because of the low initial conductivity of the soil). As power is applied, the melt travels downward into the soil at a slow rate. The final waste form consists of a vitrified monolith with positive strength and leachability characteristics. Offgases are captured in a hood that is maintained at a negative pressure. Offgas treatment consists of quenching, scrubbing, mist elimination, heating, particulate filtration, and activated carbon adsorption.

The in situ soil vitrification process has successfully destroyed organic pollutants by pyrolysis and incorporated inorganic pollutants within a glass-like vitrified mass. The process, however, is limited by the physical characteristics of the soil (including void volume size, soil chemistry, rubble content, and the amount of combustible organics in the soil). The process has been operated in pilot-scale and full-scale tests at DOE's Hanford Site, Oak Ridge National Laboratory, and Idaho National Engineering Laboratory (EPA 1993).

D.7.16 ReaCTIVE ADDITIVE STABILIZATION PROCESS

The reactive additive stabilization process uses a high-surface-area additive to enhance the vitrification of SRS nickel electroplating sludges and incinerator wastes.

The additive used in the reactive additive stabilization process is a reactive high-surface-area silica. This additive was found to increase bonding of the waste species by increasing the solubility and tolerance of borosilicate and soda-lime-silica glass formulations. The silica also lowers the glassification temperature and allows large waste volume reductions due to increased waste loadings. The final glass is in compliance with applicable EPA standards.

The reactive additive stabilization process increases the rates of dissolution and retention of hazardous, mixed, and heavy metal species in the vitrified product. Volatility concerns are reduced because the reactive additive stabilization process lowers the melting temperatures of the waste due to the addition of the highly reactive, high-surface-area silica additive. The process typically reduces the waste volume by 86 to 97 percent and thus maximizes cost savings.

The reactive additive stabilization process is an acceptable method for vitrifying radioactive materials, transuranic wastes, incinerator ash, waste sludges, and other solid and aqueous wastes. Laboratory-scale studies at SRS have demonstrated that the reactive additive stabilization process is a viable process for treating hazardous and mixed wastes by achieving large waste-loading percentages, large volume-reduction percentages, and large cost savings (Moghissi et al. 1993).

D.7.17 CYCLONIC FURNACE

The cyclonic furnace is designed to treat solid, liquid, soil slurry, or gaseous wastes by high-temperature combustion and vitrification. The high turbulence in the combustion chamber helps ensure that temperatures are high enough (1,300 to 1,650°C) to melt high-ash-content feed material. Highly contaminated inorganic hazardous wastes and soils that contain heavy metals and organic constituents are the primary waste forms targeted by this technology. The processes can also be applied to mixed wastes containing lower-volatility radionuclides, such as strontium and transuranic elements.

The waste that enters the cyclonic furnace is melted, and the organics are destroyed in the resulting gas phase or in the molten slag layer that forms on the inner wall of the furnace barrel. Organics, heavy metals, and radionuclides are captured in the slag that exits the furnace from a tap at the cyclone throat. The slag then solidifies, rendering its hazardous constituents nonleachable.

This technology has been tested in pilot-scale demonstrations. Results showed that almost 95 percent of the noncombustible synthetic soil matrix is incorporated into the slag, and simulated radionuclides are immobilized. Current demonstrations are being performed under the EPA's Superfund Innovative Treatment Evaluation Demonstration Program (Roy 1992a, b; EPA 1993).

D.7.18 FLUIDIZED BED CYCLONIC AGGLOMERATING INCINERATOR

Fluidized bed technology uses a catalyst to facilitate complete destruction of hazardous species at low temperatures. The fluidized bed cyclonic agglomerating incinerator consists of a two-stage process in which solid, liquid, and gaseous organic wastes can be efficiently destroyed while solid, nonvolatile inorganic contaminants can be agglomerated into a pellet-sized, vitrified waste form. In the first stage, a fluidized bed reactor operates as a low-temperature desorption unit or a high-temperature agglomeration unit. Fuel, oxidant, and waste is fed to the fluidized bed reactor where the waste undergoes rapid gasification and combustion. Inorganic and metallic solids will be agglomerated into glassy pellets that will meet the requirements of the toxicity characteristic leaching procedure. Gases from the fluidized bed (which consist of products of both complete and incomplete combustion) are fed to the second stage of the process (which consists of a cyclonic combustor that will oxidize carbon monoxide and organics to carbon dioxide and water). Volatilized metals are collected in a downstream scrubber. This technology has undergone bench-scale demonstration. Toxicity characteristic leaching procedure test results, however, have been inconclusive to date. Design and construction of a pilot plant were completed, and testing is in progress.

The low operating temperatures of the fluidized bed process are not conducive to nitrogen oxide formation. Volatilization of radionuclides and heavy metals and acidic offgas can be treated in situ. Offgases can be treated with high efficiency particulate air filters. Fluidized bed technology is compatible with a wide range of wastes, including combustible and non-combustible solids, liquids, and sludges. From these wastes, the fluidized bed produces a secondary solid waste from catalyst attrition that requires further treatment. These solids are collected and solidified by other methods (e.g., polymer solidification, microwave solidification, or cementation) to produce a final waste form.

DOE and EPA are currently developing hybrid fluidization systems, such as the fluidized bed cyclonic agglomeration. Los Alamos National Laboratory is researching new techniques for monitoring radionuclides and heavy metals in the offgas stream. DOE is considering a project to demonstrate the feasibility of a fluidized bed unit to treat a radioactive solvent waste. The unit under consideration will include a patented combustion process that captures contaminants in-bed and prevents the formation of glass deposits as seen with conventional combustion techniques (EPA 1993).

D.7.19 CATALYTIC COMBUSTION IN A FLUIDIZED BED ReaCTOR

Catalytic combustion in a fluidized bed reactor is a low-temperature (525 to 600 °C) treatment for lowlevel mixed waste; it is currently in an active research and development stage. The anticipated waste for this process, however, is one primarily made of cellulosic matter, such as paper, latex, wood, and polyvinyl chlorides. Such wastes present processing problems because some compounds thermally degrade to yield toxic byproducts. For example, polyvinyl chloride degradation produces hydrochloric acid vapors, which can react to form chlorinated hydrocarbons. The addition of sorbants may, therefore, be required to implement in situ capture of chlorinated hydrocarbons.

Several advantages are offered by combining flameless fluidized bed combustion with catalytic afterburning, rather than by using high-temperature incineration. Two advantages are elimination of (1) the need for refractory lining in the reactor and (2) the emission of radioactive material from the fluidized bed. Radioactive material generally does not volatilize at temperatures below 800 °C.

Research at the Colorado School of Mines has been conducted to determine the catalysts that best contribute to the destruction of toxic (chemically hazardous) waste material. Tests have shown that catalysts containing chromia are the most successful in achieving high destruction and removal percentages. Research has also shown that this method could be a viable alternative method for volumetric reduction of low-level mixed waste. The studies have also shown that these methods may be applicable to transuranic wastes (Murray 1993; International Incineration Conference 1994).

D.7.20 MICROWAVE SOLIDIFICATION

Microwave solidification uses microwave energy to heat and melt homogeneous wet or dry solids into a vitrified final waste form that possesses high-density and leach-resistant attributes. The system includes an "in-drum" melting cavity that isolates the molten waste and the drum from the process equipment. Glass-forming frit is added to the waste contained in the drum, which is then exposed to high-energy microwaves to produce a vitrified final waste form that is suitable for land disposal. Advantages of microwave processing over conventional thermal treatment include an elimination of the need for heating elements or electrodes in direct contact with the waste, potential to reduce volatile radionuclide emissions, and a significant volume reduction.

The process is energy efficient and controllable because of direct coupling between the microwave energy and the waste. The results of bench-scale experiments at DOE's Rocky Flats Plant are encouraging and support the potential use of microwave technology in the production of vitrified waste forms. Further work is being done to optimize critical process parameters, including waste loading and borax concentration in the glass-forming frit (International Incineration Conference 1994; DOE 1994b).

D.7.21 MIXED WASTE TReaTMENT PROCESS

The mixed waste treatment process treats contaminated soils by separating the hazardous and radioactive contaminants into organic and inorganic phases. This process is an integration of individually demonstrated technologies, including thermal desorption, gravity separation, water treatment, and chelant extraction. The initial treatment step involves sizing the incoming waste, after which volatile organics are removed by indirectly heating the waste in a rotating chamber. The volatilized organics and water are separately condensed, and the volatile organics are decanted for further treatment and disposal. The waste is rehydrated and inorganic constituents are removed by gravity separation, chemical precipitation, and chelant extraction. Gravity separation is used to separate higher density particles, a potassium ferrite formulation is added to precipitate radionuclides, and the insoluble radionuclides are removed through chelant extraction. The chelant solution then passes through an ion exchange resin to remove the radionuclides and is recycled to the process. The contaminants from all waste processes are collected as concentrates for recovery or disposal.

This technology has been developed for processing soil contaminated with organics, inorganics, and radioactive material. Bench-scale and pilot-scale testing for individual components of the treatment process is ongoing under EPA's Superfund Innovative Treatment Evaluation Emerging Technology Program using DOE, U.S. Department of Defense, and commercial wastes. Thermal separation has been shown to remove and recover PCBs, gravity separation of radionuclides has been successfully demonstrated, and chelant extraction has long treated surface contamination in the nuclear industry (EPA 1993).

Table D-3. Summary of emerging technologies.

Technology type	Technology	Development statusa	Waste typeb	Waste form
Biological	Bioscrubber	Bench	Off-gas/Organics	Liquid and Gas
Biological	Biosorption	Pilot	HLW/Mixed	Supernatant/Saltcake
Biological	White Rot Fungus	Bench	Carbon-Based	Solid and Liquid
Chemical	Aqueous Phase Catalytic Exchange	Bench	Tritiated Water	Liquid
Chemical	Biological/Chemical Treatment	Pilot	Heavy Metal	Solid
Chemical	Dechlorinization	Bench	Mixed/PCB	Solid and Soil
Chemical	Gas-Phase Chemical Reduction	Full	PCBs, Dioxins	Liquid and Sludge
Chemical	Nitrate to Ammonia and Ceramic Process	Bench	Mixed	Aqueous
Chemical	Resorcinol-Formaldehyde Ion Exchange Resin	Bench	HLW	Supernatant
Chemical	Supercritical Water Oxidation	Bench	Mixed	Solid and Liquid
Chemical	Wet Air Oxidation	Bench	LLW/Mixed	Solid and Liquid
Chemical	Wet Chemical Oxidation (Acid Digestion)	Bench	Mixed	Solid and Liquid
Chemical	Evaporation and Catalytic Oxidation	Full	VOC/PCB/Mixed	Solid and Sludge
Chemical	Biocatalytic Destruction	Bench	LLW/Mixed	Aqueous
Chemical	Electrochemical Oxidation	Pilot	Mixed	Solid and Liquid
Chemical	Mediated Electrochemical Oxidation	Pilot	Mixed	Solid and Oils
Physical	Acoustic Barrier Particulate Separator	Pilot	Off-Gas	Particulate
Physical	Chemical Binding/Precipitation/Physical Separation	Pilot	LLW/Mixed	Water/Sludge/Soil
Physical	Chemical Treatment and Ultrafiltration	Pilot	Heavy Metal	Liquid
Physical	Heavy Metals and Radionuclide Polishing Filter	Bench	LLW/Heavy Metal	Liquid
Physical	Membrane Microfiltration	Pilot	Heavy Metal	Solid and Liquid
Physical	Electrodialysis	Full	Metals	Liquid
Physical	Freeze Crystallization	Pilot	Mixed	Liquid
Physical	High-Energy Electron Irradiation	Full	Organics	Liquid and Sludge
Physical	Ultraviolet Oxidation	Full	Organics	Liquid
Physical	Pressure Washing and Hydraulic Jetting	Full	LLW	Solid
Physical	Soil Washing	Bench	LLW	Solid and Soil
Physical	Steam Reforming	Full	Mixed	Solid/Liquid/Sludge
Stabilization	Polyethylene Encapsulation	Full	Mixed	Solid and Sludge
Stabilization	Pozzolanic Solidification and Stabilization	Full	LLW/Mixed	Solid and Sludge
Stabilization	Vinyl Ester Styrene Solidification	Full	LLW/Mixed	Solid
Thermal	Flame Reactor	Full	Organics/Metals	Solid/Sludge/Soil
Thermal	Thermal Desorption Process	Full	LLW/Mixed	Liquid
Thermal	Unvented Thermal Process	Bench	Mixed	Solid and Liquid
Thermal	Molten Salt Oxidation and Destruction Process	Pilot	Mixed	Solid and Liquid
Thermal	Quantum-Catalytic Extraction Process	Bench	Mixed/Metals	Solid/Liquid/Gas
Thermal	Infrared Thermal Destruction	Full	Organic/Metal	Solid/Liquid
Thermal	Plasma Hearth Process	Bench	LLW/TRU/Mixed	Solid and Liquid
Thermal	Plasma Arc Centrifugal Treatment	Pilot	Mixed	Solid/Liquid/Gas

Table D-3. (continued).

Technology type	Technology	Development statusa	Waste typeb	Waste form
Thermal	Graphite Electrode DCc Arc Furnace	Pilot	LLW/TRU/Mixed	Solid
Thermal	Packed Bed Reactor/Silent Discharge Plasma Apparatus	Bench	PCB/Mixed	Liquid
Thermal	Electric Melter Vitrification	Bench	HLW/LLW/Mixed	Solid and Sludge
Thermal	Stirred Melter Vitrification	Bench	LLW/Mixed	Solid and Sludge
Thermal	Modular Vitrification	Pilot	LLW/Mixed	Solid and Sludge
Thermal	Vortec Process	Pilot	Mixed	Solid and Liquid
Thermal	In Situ Soil Vitrification	Full	TRU/Mixed	Buried and Soil
Thermal	Reactive Additive Stabilization Process	Bench	Mixed/LLW/TRU	Solid and Liquid
Thermal	Cyclonic Furnace	Pilot	Mixed	Solid/Liquid/Gas
Thermal	Fluidized Bed Cyclonic Agglomerating Incinerator	Pilot	Mixed	Solid/Liquid/Gas
Thermal	Catalytic Combustion in a Fluidized Bed Reactor	Bench	Mixed	Solid and Liquid
Thermal	Microwave Solidification	Pilot	Mixed	Wet and Dry Solids
Various	Mixed Waste Treatment Process	Pilot	Mixed	Soil

a. Bench - Technology is being proven on a bench-scale level.

Pilot - Technology has been proven on a bench-scale level and is being tested and evaluated on a pilot-scale level.

Full - Technology is being demonstrated for full-scale commercial or government application.

b. HLW = High-level radioactive waste.

LLW = Low-level radioactive waste.

PCB = Polychlorinated biphenyls.

TRU = Transuranic.

VOC = Volatile organic compounds.

c. DC = Direct current.

D.8 References

Apte, N., 1993, "Hazardous Waste Treatment Technologies - An Inventory," Hazmat World, Vol. 6, No. 8, pp. 27-32.

Bumpus, J. A., T. Fernando, M. Jurek, G. J. Mileski, and S. D. Aust, 1989, "Biological Treatment of Hazardous Waste by Phanerochaete chrysosporium," in Proceedings of the Engineering Foundation Conference, Lewandowski, G., P. Armenante, and B. Baltzis, eds., Long Boat Key, Florida, pp. 167183.

Connors, R., no date, "Bioremediation Utilizing White Rot Fungi," Earthfax Engineering, Inc.

Diversified Technologies, 1993, "Treatment of Silver-Coated Packing Material," Diversified Technologies Proposal No. P-323, WSRC Special Consolidated Solicitation No. E10600-E1, Aiken, South Carolina.

DOE (U.S. Department of Energy), 1993, Savannah River Site Consolidated Incineration Facility Mission Need and Design Capacity Review, Draft B, Savannah River Operations Office, Aiken, South Carolina, July 7.

DOE (U.S. Department of Energy), 1994a, Technology Catalog, First Edition, DOE/EM-0138P, Office of Environmental Management and Office of Technology Development, Washington, D.C.

DOE (U.S. Department of Energy), 1994b, Mixed Waste Integrated Program (MWIP), Technology Summary, DOE/EM-0125P, Office of Environmental Management and Office of Technology Development, Washington, D.C.

DOE (U.S. Department of Energy), 1994c, Supercritical Water Oxidation Program (SCWOP), Technology Summary, DOE/EM-0121P, Office of Environmental Management and Office of Technology Development, Washington, D.C.

EPA (U.S. Environmental Protection Agency), 1991, The Superfund Innovative Technology Evaluation Program, Technology Profiles, EPA/504/5-91/008, Fourth Edition, Washington, D.C., November.

EPA (U.S. Environmental Protection Agency), 1992a, The Superfund Innovative Technology Evaluation Program, Technology Profiles, EPA/540/R-92/077, Fifth Edition, Washington, D.C., November.

EPA (U.S. Environmental Protection Agency), 1992b, Horsehead Resource Development Company, Inc. Flame Reactor Technology, Applications Analysis Report, EPA/540/A5-91/005, Washington, D.C.

EPA (U.S. Environmental Protection Agency), 1992c, Retech, Inc., Plasma Centrifugal Furnace, Applications Analysis Report, EPA/540/A5-91/007, Washington, D.C.

EPA (U.S. Environmental Protection Agency), 1992d, Vitrification Technologies for Treatment of Hazardous and Radioactive Waste Handbook, EPA/625/R-92/002, Washington, D.C.

EPA (U.S. Environmental Protection Agency), 1993, The Superfund Innovative Technology Evaluation Program, Technology Profiles, EPA/540/R-93/526, Sixth Edition, Washington, D.C., November.

EPA (U.S. Environmental Protection Agency), 1994, "Demonstration of the High Voltage Environmental Applications, Inc. High Voltage Electron Beam Technology," SITE Program Fact Sheet, August.

Feizollahi, F. and D. Shropshire, 1994, Interim Report: Waste Management Facilities Cost Information for Mixed and Low-Level Waste, EGG-WM-10962, Idaho National Engineering Laboratory and EG&G Idaho, Inc.

Herbst, C. A., E. P. Loewen, C. J. Nagel, A. Protopapas, 1994, "Quantum-Catalytic Extraction Process Application to Mixed Waste Processing," prepared for Molten Metal Technology, Inc., Waltham, Massachusetts.

International Incineration Conference, 1993, Thermal Treatment of Radioactive, Hazardous Chemical, Mixed, Energetic, Chemical Weapon, and Medical Waste, Knoxville, Tennessee, May 3-7.

International Incineration Conference, 1994, Thermal Treatment of Radioactive, Hazardous Chemical, Mixed, Munitions, and Pharmaceutical Wastes, Houston, Texas, May 9-13.

Mason, J. B., no date, Modular Enviroglass Vitrification Technology for Low-Level Radioactive and Mixed Wastes, VECTRA Document No. SP-5010-01, Revision 2, Richland, Washington.

Moghissi, A. A. and G. A. Benda, eds., 1991, Mixed Waste: Proceedings of the First International Symposium, Baltimore, Maryland, August 26-29.

Moghissi, A. A., R. R. Blauvelt, G. A. Benda, and N. E. Rothermich, eds., 1993, Mixed Waste: Proceedings of the Second International Symposium, Baltimore, Maryland, August.

Murray, J. R., 1993, "Demonstration of Fluidized-Bed Combustion for Treatment of Solvent Tank Liquid Waste," WSRC Special Consolidated Solicitation No. E10600-E1, Advanced Science, Inc., Oak Ridge, Tennessee, September 29.

Roy, K. A., 1992a, "Cyclonic Combustor Treats Wide Range of Industrial Wastestreams," Hazmat World, Vol. 5, No. 12, pp. 84-85.

Roy, K. A., 1992b, "Thermo-Chemical Reduction Process Destroys Complex Compounds," Hazmat World, Vol. 5, No. 12, pp. 77-79.

Scientific Ecology Group, Inc., 1993, "Treatment of Low-Level Waste Lead," Technical Abstract Number SW-03, Westinghouse Savannah River Company Special Consolidated Solicitation Number E10600-E1, Aiken, South Carolina.

Sturm, H. F., 1994, "DOE's Efforts in Identification and Development of Innovative Technologies: Vendor Forum," presented at SPECTRUM '94, Atlanta, Georgia.

Wilks, J. P., 1989, "Wet Oxidation of Mixed Organic and Inorganic Radioactive Sludge Wastes from a Water Reactor," in 1989 Incineration Conference Proceedings, May.

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Appendix D