review of commercial innovative technologies for hazardous waste

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Review of Commercial Innovative Technologies for Hazardous Waste James J. Cudahy Focus Environmental, Inc., 9050 Executive Park Dr., Knoxville, TN 37923 A number of Innovative Technologieshave been developed since the late 1980kfor the treatment ofResource Conserva- tion and Recovery Act (RCRA) hazardous wastes The devel- opment of these technologzes has been encouraged by the Bwzronmental Protectzon Agency (EPA), the Department of Energ)’ (DOE) and the Department of Defense (DOD) As pwrt of the ruperfund Innovative Technology Evaluation program, the EPA has evaluated some of these technologies for the treatment of soils contaminated wath RCRA har- ardozis constituents The DOE has extensively studzed and eiuluated these technologiesfor the treatment of mixed (RCRA plus radioactztle) waste The DOD has also studzed these technologzesforthe chemical demzlztarizatzon of chem- ical uarfiire agents The technology experaence andperfor- mance oj fzue Innovative Technologies that have been demonstrated on a full-scale commercial basis are dts- LZISSed INTRODUCTION A number of medium and high temperature Innov- ative Technologies have been developed since the late 1980’s for the treatment of Resource Conservation and Recovery Act (RCRA) hazardous wastes. The deidopnient of these technologies has been encour- aged by the Environmental Protection Agency (EPA), the Department of Energy (DOE) and the Department of Defense CDOD). As part of the Superfund Innova- tive Technology Evaluation (SITE) program, the EPA has evaluated some of these technologies for the treat- ment of soils contaminated with RCRA hazardous con- stituents [1,2.31. The DOE has extensively studied and evaluated these technologies for the treatment of mixed (RCRA plus radioactive) waste [4,51. The DOD has also studied these technologies for the chemical demilitarization of chemical warfare agents [6,71. While most of the experience with these technologies is either on a bench or pilot-scale basis, the author has identified five of these medium and high temperature Innovative Technologies which have been demon- strated on a full-scale commercial basis. Descriptions and operating experience for these technologies have been obtained from the literature, vendor publica- tions, discussions with vendor representatives and the author’s involvement in DOE and DOD Innovative Technology Peer Review Panels. TECHNOLOGY DESCRIPTIONS AND EXPERIENCE The following five medium and high temperature Innovative Technologies for hazardous wastes have been demonstrated and operated on a full-scale com- mercial basis [Sl: Eco Logic Gas Phase Chemical Reduction Process GTS Duratek Electric, Joule-Heated Glass Melter Molten Metals Catalytic Extraction Process Retech Plasma Arc Centrifugal Treatment Process GTS Duratek Steam Reforming Process innovative technologies through January 1999 follow: Descriptions and experience summaries for the five Eco Logic Gas Phase Chemical Reduction Process The Eco Logic Gas Phase Chemical Reduction process treats organic hazardous waste in a non-oxida- tive hydrogen rich atmosphere at approximately 165O0F (9OOOC) and ambient pressure to produce a fuel gas as reaction products from the wastes [31. The process also employs steam reforming to enhance the hydrogenation reactions. The fuel gas which is pro- duced contains mostly carbon monoxide, methane and hydrogen [3]. The fuel gas is either burned on-site in a boiler associated with the Eco Logic process, used in the reactor or transported off-site for use as a fuel gas. Aqueous and organic liquid wastes are treated in the reactor. Organic contaminants in drums or bulk solid wastes are vaporized in a pretreatment operation such as the Eco Logic Thermal Reduction Batch Processor (TRBP). The TRBP is a high temperature chamber in which hot recirculation gases from the reactor, at up to about 1000°F (540’0, desorb organic contaminants and sweep them into the reactor “91. Contaminated soils are treated in a Thermal Reduction Mill (TRM) which is a ball mill heated by the reactor gas. The hot reactor recirculation gas desorbs organic contaminants and sweeps them into the reactor 1101. Environmental Progress (Vo1.18, No.4) Winter 1999 285

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Review of Commercial Innovative Technologies for Hazardous Waste James J. Cudahy Focus Environmental, Inc., 9050 Executive Park Dr., Knoxville, TN 37923

A number of Innovative Technologies have been developed since the late 1980kfor the treatment ofResource Conserva- tion and Recovery Act (RCRA) hazardous wastes The devel- opment of these technologzes has been encouraged by the Bwzronmental Protectzon Agency (EPA), the Department of Energ)’ (DOE) and the Department of Defense (DOD) As pwrt of the ruperfund Innovative Technology Evaluation program, the EPA has evaluated some of these technologies for the treatment of soils contaminated wath RCRA har- ardozis constituents The DOE has extensively studzed and eiuluated these technologies for the treatment of mixed (RCRA plus radioactztle) waste The DOD has also studzed these technologzesfor the chemical demzlztarizatzon of chem- ical uarfiire agents The technology experaence andperfor- mance oj fzue Innovative Technologies that have been demonstrated on a full-scale commercial basis are dts- LZISSed

INTRODUCTION A number of medium and high temperature Innov-

ative Technologies have been developed since the late 1980’s for the treatment of Resource Conservation and Recovery Act (RCRA) hazardous wastes. The deidopnient of these technologies has been encour- aged by the Environmental Protection Agency (EPA), the Department of Energy (DOE) and the Department of Defense CDOD). As part of the Superfund Innova- tive Technology Evaluation (SITE) program, the EPA has evaluated some of these technologies for the treat- ment of soils contaminated with RCRA hazardous con- stituents [1,2.31. The DOE has extensively studied and evaluated these technologies for the treatment of mixed (RCRA plus radioactive) waste [4,51. The DOD has also studied these technologies for the chemical demilitarization of chemical warfare agents [6,71. While most o f the experience with these technologies is either on a bench or pilot-scale basis, the author has identified five of these medium and high temperature Innovative Technologies which have been demon- strated on a full-scale commercial basis. Descriptions and operating experience for these technologies have

been obtained from the literature, vendor publica- tions, discussions with vendor representatives and the author’s involvement in DOE and DOD Innovative Technology Peer Review Panels.

TECHNOLOGY DESCRIPTIONS AND EXPERIENCE The following five medium and high temperature

Innovative Technologies for hazardous wastes have been demonstrated and operated on a full-scale com- mercial basis [Sl:

Eco Logic Gas Phase Chemical Reduction Process GTS Duratek Electric, Joule-Heated Glass Melter Molten Metals Catalytic Extraction Process Retech Plasma Arc Centrifugal Treatment Process GTS Duratek Steam Reforming Process

innovative technologies through January 1999 follow: Descriptions and experience summaries for the five

Eco Logic Gas Phase Chemical Reduction Process The Eco Logic Gas Phase Chemical Reduction

process treats organic hazardous waste in a non-oxida- tive hydrogen rich atmosphere at approximately 165O0F (9OOOC) and ambient pressure to produce a fuel gas as reaction products from the wastes [31. The process also employs steam reforming to enhance the hydrogenation reactions. The fuel gas which is pro- duced contains mostly carbon monoxide, methane and hydrogen [3]. The fuel gas is either burned on-site in a boiler associated with the Eco Logic process, used in the reactor or transported off-site for use as a fuel gas. Aqueous and organic liquid wastes are treated in the reactor. Organic contaminants in drums or bulk solid wastes are vaporized in a pretreatment operation such as the Eco Logic Thermal Reduction Batch Processor (TRBP). The TRBP is a high temperature chamber in which hot recirculation gases from the reactor, at up to about 1000°F (540’0, desorb organic contaminants and sweep them into the reactor “91. Contaminated soils are treated in a Thermal Reduction Mill (TRM) which is a ball mill heated by the reactor gas. The hot reactor recirculation gas desorbs organic contaminants and sweeps them into the reactor 1101.

Environmental Progress (Vo1.18, No.4) Winter 1999 285

A wet scrubbing system is used to remove particu- late, soot, metals, light hydrocarbons and inorganic gaseous reaction products such as carbon monoxide, carbon dioxide, hydrogen chloride and hydrogen sul- fide, from the fuel gas. Eco Logic's design for the treatment of polychlorinated biphenyls (PCBs) and chlorinated pesticides includes a four stage scrubbing system. A two stage water scrubber is used for the recovery and removal of hydrogen chloride, soot, par- ticulate and metals. The first stage of the water scrub- ber recovers concentrated hydrochloric acid and the second stage of the water scrubber is used for addi- tional removal of the hydrogen chloride. The third stage is a wash oil scrubber for the removal of soot and hydrocarbons such as benzene and naphthalene. The fourth stage is a monoethanolamine scrubber for removal of hydrogen sulfide, carbon monoxide and carbon dioxide [ll]. A block flow diagram of the Eco Logic system is shown in Figure 1.

Eco Logic has operated two full-scale hazardous waste processing systems. The first system was estab- lished in 1995 in Kwinana, Western Australia, for the commercial disposal of PCBs and chlorinated pesti- cide wastes for clients throughout Australia. The facili- ty operates 24 hours per day, seven days per week [la]. Since January 1997, 855 tons (777 tonnes) of PCB contaminated wastes which were mainly capacitors and PCB oil and 166 tons (150 tonnes) of DDT and other chlorinated pesticides have been treated at the Kwinana facility [11]. During a demonstration test in Australia the Eco Logic unit successfully treated 2.4

Reduction Batch

Processor (TRBP)

tons ( 2 . 2 tonnes) of a high strength solution of dicliloro-diphenyl-trichloroethane (DDT) and toluene during a 24 hour sustained rate test. The Destruction and Removal Efficiency (DRE) obtained for the DDT was greater than 99.9999% 1131. As a result of design improvements implemented in the spring of 1998, the Thermal Reduction Batch Processor has a treatment capacity o f approximately 80 tons (73 tonnes) per month of bulk solid wastes and about 12 tons (11 tonnes) of bulk wastes per batch 1111.

The second system was operated at a General Motors of Canada Limited foundry in St. Catherines, Ontario, Canada. In the fall of 1997. Eco Logic com- pleted a full-scale denionstration at St. Catherines. During this project, which started in February 1996, over 1,000 tons (909 tonnes) of PCB contaminated material was treated, including PCB oils containing chlorobenzenes and dioxins [11,141.

-

GTS Duratek Electric, Joule-Heated Glass Melter The GTS Duratek process uses glass making tech-

nology to encapsulate waste constituents into a glass matrix which has excellent leach resistance. Pilot data as well as full-scale processing on DOE wastes has shown that the GTS Duratek process produces a glass with very good leach resistance when tested with the EPA's Toxic Characteristic Leaching Procedure test [li,l61. The Duratek process uses an electric. joule- heated, refractory lined glass melter which is typically operated at about 2100°F (1150°C). The molten glass bath is operated oxidatively with an air bubbling sys-

Recirculation Gas Heater (RGH) -

Monoethanolamine (MEA)

9 I 1 I I \

Treated Solids

rcaus"cl ~

-

Cl- Filters

Weak Tank Acid

FIGURE 1. Eco Logic Ilrocess Flow Diagram

*El-*El-- Release

286 Winter 1999

tem which distributes air throughout the glass bath. The waste feed is deposited on the surface of the molten glass bath where heat from the glass bath evaporates water from the waste, oxidizes organic waste constituents and fuses the inorganic con- stituents into the glass melt [171.

GTS Duratek operates one full-scale glass melter, the DuraMelter 5000A, which is in commercial opera- tion at the DOE’S Savannah River Site (SRS). The DuraMelter 5000A has a melt basin that holds approxi- mately 550 gallons (2,080 liters) of molten glass. The glass bath is heated by three parallel submerged elec- trodes and is controlled to a temperature of 2100°F (1 150T) . The molten glass is discharged through either of two side exiting pour spouts. This melter has a nominal production rate of 5 tons (4.5 tonnes) of glass per day while processing the SRS waste [161 The glass can hold varying amounts of waste ash con- stituents, depending on the type of inorganic com- pounds being treated and glass quality considerations. An air pollution control system is required for the Duratek system for the removal of particulate, metals, hydrogen chloride and nitric oxides. The air pollution control system at the SRS includes a water spray quench . two packed bed scrubbers operating in series. two high efficiency mist eliminators operating

GLASS FORMING CHEMICALS

1

in parallel, a baghouse and a high efficiency particu- late air filter (HEPA) [16,171. A block flow diagram of the GTS Duratek system is shown in Figure 2.

At the SRS, the DuraMelter 5000A was used to treat approximately 660,000 gallons (2,500,000 liters) of a hazardous and radioactive aqueous waste sludge con- taining nickel and uranium. From October 1996 to March 1997, the DuraMelter 5000A had treated about 100,000 gallons (378,500 liters) of this sludge [MI. This is a throughput rate of about 850 tons (773 tonnes) of waste per year. On March 27, 1997, GTS Duratek sus- pended operation of the DuraMelter 5000A at the SRS and decided to undertake extensive repairs and facili- ty modifications, including melter box replacement, before resumption of waste processing (18). The DuraMelter 5000A unit became operational again in December 1997 and completed processing the majori- ty of the waste inventory by September 1998 at a rate of over 3,000 tons (2,727 tonnes) of waste per year. In that time, over 990 tons (900 tonnes) of glass in approximately 2,800 71-gallon (269 liter) drums was produced [161. All of the glass that was produced passed the EPA’s Toxic Characteristic Leaching Proce- dure (TCLP) test procedure. From October 1998 to January 1999, GTS Duratek has clean closed eight of the nine waste storage tanks at the SRS [161.

ELECTRIC HEATERS

L I

FIGURE 2. GTS Duratek Glass Melter Process Flow Diagram

Environmental Progress (Vo1.18, No.4) Winter 1999 287

GTS Duratek and British Nuclear Fuels have teamed to win the Tank Waste Remediation System (TWRS) contract at the DOE’S Hanford site in Rich- land, Washington. The TWRS project involves the vitri- fication of the j 4 million gallons (204 million liters) of radioactive waste created during the production of nuclear weapons . As part of this project, the DuraMelter technology will be employed to stabilize the waste. GTS Duratek will design three melters, each capable of producing 10 tons (9.1 tonnes) of glass per day, to process the majority of the waste. One 1.5 ton (1.4 tonnes) per day melter will also be designed to stabilize a highly radioactive fraction of the waste inventory 1161.

.

Molten Metals Catalytic Extraction Process The Molten Metals Catalytic Extraction Process

(CEP) is a process that recycles organic and inorganic hazardous waste in a non-oxidative refractory lined molten metal bath. The molten metal can be iron, nickel or copper, but iron is typically used. In the CEP, liquid wastes, finely divided solids or pumpable slur- ries, are fed to a sealed molten metal reactor through bottom entering tuyeres. Oxygen and methane are also fed to the metal bath either through a top enter- ing lance or a bottom entering tuyere [71. The molten metal bath and the wastes are heated to 2400 to 3000°F (1350 to 1650°C) by an electric induction coil embedded within the refractory lining.

Tapping ports in the vessel sidewalls allow recov- ery of the metal and slag phases generated during operation 191. The high temperature and catalytic properties of the molten metal break down the wastes and produce a reaction gas, a ceramic slag and a recy- clable metal such as iron [171. In order to produce a

HEPA THERMAL FILTER OXIDIZER

GAS

SCRUBBER BAGHOUSE - QUENCH - GAS

COOLER -.+

fuel gas, air pollution control equipment is required to remove inorganic impurities from the reaction gas. Typical impurities which are either removed and/or recycled from the reaction gas are particulate, soot, metals. hydrogen chloride. hydrogen cyanide, ammo- nia and hydrogen sulfide [91. The purified fuel gas contains mostly carbon monoxide and hydrogen and can be either burned on-site in a co-generation boiler associated with the Molten Metals process or trans- ported off-site for use as a fuel gas or as a feedstock for niethanol production 191. A block flow diagram of the Molten Metals system is shown in Figure 3.

On December 3, 1997, Molten Metals filed for reor- ganization under Chapter 11 bankruptcy proceedings [ZO]. In November, 1798, Allied Technology Group, Inc. (ATG) of Frernont, CA bought part of Molten Met- als‘ assets [21,221.

Prior to the bankruptcy, Molten Metals had three full-scale units in operation which were in the early stages of commercial operation. The largest reactor, which is located in Molten Metal’s Fall River Massa- chusetts Research Center, contains about 3 tons (2.7 tonnes) of metal . This unit was used mainly for research and did short batch runs on wastes. Molten Metal is reported to have performed a 93 hour com- mercial scale test in this unit on biological sludge and chlorinated hydrocarbon liquids at an operating factor of 90 percent and at feed injection rates that met unspecified commercial operation requirements [7].

The second largest reactor is located in Molten Metal’s Oak Ridge, TN Technical Center and contains about 1.5 tons (1 .4 tonnes) of metal. This unit was used for research and for commercial operation on a batch basis. The Oak Ridge Technical Center was shut down in early 1998.

WASTE

HANDLING r ATMOSPHERE

T

!4CL RECOVERY SULFUR RECOVERY

I I

RECOVERY - CATALYTIC PROCESSING

OXYGEN

NATURAL GAS

METAL 8 1 CERAMIC 1 HANDLING

CERAMIC METAL

FIGURE 3. Molten ILIetals CEP Process Flom Dlagrarn

288 Winter 1999 Environmental Progress ( V d . 18, No.4)

The third reactor is located in Molten Metal's Bear Creek, TN facility and contains about o n e ton of metal. This facility was dedicated to the recycling of radioactive ion-exchange resins from the nuclear power industry. The unit has a design capacity of 130,000 cubic feet (3,683 cubic meters) of resin per year, which is a feed rate of about 84 5 pounds (384 kilograms) per hour [81. The Bear Creek facility processed about 52,000 cubic feet (1,473 cubic meters) of ion-exchange resins in 1997 [231. ATG is now operating this process for the treatment of low level spent ion exchange resins [221.

Molten Metals had finished building a permitted full-scale commercial facility which is located in Bay City, Texas. This unit was designed to treat chlorinat- ed vent gas from a Hoechst Celanese Chemical plant and chlorinated organic liquid wastes from industry. The unit was designed to produce a synthesis gas which would have been sold to Hoechst Celanese and to recover hydrochloric acid which would have been sold to area companies. A second phase reactor was planned which would be designed for Celanese's bio- logical sludge solids and increase capacity to 35,000 tons (31,820 tonnes) [241. The Bay City facility was scheduled for start up in November 1997 [241, but was not started up because of the bankruptcy and is up for sale.

Retech Plasma Arc Centrifugal Treatment Process The Retech Plasma Arc Centrifugal Treatment

(PACT) process treats inorganic and organic waste using a plasma torch located in a melter chamber. The energy supplied by the plasma torch melts and vitri-

fies inorganic constituents in the waste and vaporizes and destroys the organic constituents [251. In the melter chamber, a rotating crucible contains waste that is kept molten by a plasma gas created by dissociating and partially ionizing nitrogen to form a hot gas stream to transfer energy into the molten waste. The rotating crucible helps to distribute the plasma energy evenly into the waste and causes the molten waste to form a large available surface for better melting and mixing [26]. Melt temperatures in the crucible are generally in the 2400 to 3000°F (1350 to 1650°C) range. The average gas temperature in the melter chamber can range from 2000 to 2400°F (1095 to 1315°C).

The gas from the melter flows to a secondary com- bustion chamber where organic oxidation is essential- ly completed at temperatures of 2000 to 2200°F (1095 to 1205°C). Following the secondary combustion chamber, the gas flows through an air pollution con- trol system to remove particulate, soot, metals, hydro- gen chloride and any other acid gases which may be present. Operational experience has shown that 1 to 2% of the metal oxides in the feed stream will exit the primary chamber and must be captured in the off-gas system. The carbon content of the slag product is very low, typically less than 0.015 per cent by weight 1271. A process schematic diagram of the Retech PACT sys- tem is shown in Figure 4.

Retech, which is a wholly owned subsidiary of Lockheed Martin Corporation, has four PACT units in commercial operation. A PACT pilot system in France, with an inside diameter of two feet (PACT-2), has been treating surrogates for low level radioactive

Recycle or

Disposal

FIGURE 4. Plasma Arc Centrifugal Treatment System Process Flow Diagram

Environmental Progress (Vol. 18, N0.4 ) Winter 1999 289

wastes since 1994 [81. The unit with the most opera- tional history is a PACT-8 system at the Moser-Glacer Company (MCG) in Switzerland which has been treat- ing hazardous wastes since 1991. This unit, which was initially used for research and demonstration purpos- es, has been permitted for commercial operation on 13 categories of hazardous waste since 1993 [271. A PACT-2 system has also been operating at the MGC Company in Switzerland on hazardous wastes. A PACT-6 pilot unit has been operational since 1989 in Butte, Montana doing research on both radioactive and hazardous wastes [25]. As of January 1998, a PACT-8 system is being installed in Munster, Germany by MCG for the treatment of military wastes. A PACT-8 unit is being assembled in Ukiah, CA and will be shipped to the Norfolk Naval Shipyard, in the summer of 1999, for the treatment of shipyard wastes [271.

Another PACT-8 system has been designed and built by Retech for the Pit 9 remediation at the Idaho National Engineering Laboratory (INEL). This unit uses a 1500 k w plasma torch. Recent modeling based on data from the two MGC PACT units indicates that the full scale, PACT-8 unit is capable of a throughput of 1558 pounds (708 kilograms) per hour of waste feed at 23 percent organic content. Lockheed Martin is hopeful that throughput enhancements are possible which will result in waste feedrates to the PACT-8 of over 2000 pounds (909 kilograms) per hour [261. Cur- rently, the combustible organic content of the waste is the limiting parameter on throughput based on com- bustion gas flowrate limitations to the air pollution control system. Lockheed Martin also believes that the current operational availability of 43 percent can be potentially improved to about 80 percent [261. The air pollution control system for the Pit 9 system is designed for the capture of radioactive metals, other particulate, soot, hydrogen chloride, and sulfur diox- ide. The system includes a cyclone, spray quench

S T E M REFORMING SYSTW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

tower, packed bed absorber, a Hydrosonics scrubber, a chiller to cool the gas to 105°F (40°C) for mercury removal, cyclone and mesh mist eliminators, a flue gas reheater. prefilters and HEPA filters [261. As of Jan- uary 1999, the unit is still being stored at the Retech facility in Ukiah, awaiting the outcome of contract negotiations between Lockheed Martin and the DOE about the Pit 9 project [271.

GTS DURATEK STEAM REFORMING PROCESS In April 1997, GTS Duratek acquired the Scientific

Ecology Group (SEG) radioactive waste treatment facility in Oak Ridge, TN [28]. At the Oak Ridge facility SEG operated a steam reforming process, which was formerly known as the Synthetica Detoxifier, to treat inorganic and organic wastes in two stages. During the first stage. hydrocarbons in the waste are evapo- rated in a waste feed evaporator using superheated steam. The steam reforming of the hydrocarbons starts to occur at temperatures of 600 to 1100°F (315 to 59 5°C) and converts the hydrocarbons to a fuel gas. The fuel gas typically contains carbon monoxide. hydrogen, some light hydrocarbons such as methane, carbon dioxide and water. The gases from the evapo- rator are fed to the second stage detoxification reactor where electrical heating and additional superheated steam are used t o raise the temperature of the gases to about 2100 to 2200°F (1150 to 1200°C) where the steam reforming reaction is essentially completed [291. The fuel gas can either be burned on-site in a boiler, transported off-site for use as a fuel gas, or treated in an air pollution control system.

GTS Duratek employs one full scale commercial Steam Reforming unit at its Oak Ridge, TN treatment facility and has operated mobile full scale units at the Palo Verde, A 2 nuclear power plant and the Trojan nuclear power plant in Rainier, O R . The Oak Ridge unit can process three to four drums of high organic

D STACK

FIGURE 5. GTS Duratek S t e a m Reforrning Process Flow Diagram

En"iron*nental Prc>grrss ( V d . 1.3. Nc1 .4 ) 290 Winter 1999

~~~~~~~~ ~~ ~ ~ ~

Table 1. Full-Scale Experience of Innovative Technologies

Technology Full-scale Capacity Rad/Mixed Haz Waste PCBs operation since (Tons/yr)(a)

______ ~ _ _ _ _ ~ - -

Eco Logic gas phase reduction May-95 1,000 X X

GTS Duratek glass melter Oct-96 3,000 X

Molten Metals Dec-96 1,000 X

(a) - To convert to tonnedyr, multiply by 0.909

content waste per day or about 20 pounds (9 kilo- grams) per hour [161. About 120,000 pounds (54,545 kilograms) of wastes have been treated by the Steam Reforming units at Oak Ridge through April 1997 [161. The unit primarily processed low level radioactive waste such as dry active waste (DAW) and laboratory animals. Several treatability studies were also success- fully conducted on mixed waste sludges. A process flow diagram for the Oak Ridge unit is shown in Fig- ure 5 . The fixed base Oak Ridge unit was designed primarily to process and return volume reduced wastes to the customer and was shut down when other disposal options became available for dry active waste (DAW) [161.

The Palo Verde unit featured a continuous screw feed evaporator and had a throughput of 1340 pounds (609 kilograms) per day. About 500,000 pounds (227,273 kilograms) of spent ethylene diamine tetra- acetic acid (EDTA) cleaning solution were treated dur- ing the life of the project in 1993 and 1994 [161. The steam reforming unit was in operation at the Trojan plant from July 1997 to about mid November 1997 treating highly radioactive debris, spent fuel pellets and sludges from the spent fuel pool. During this operation, the steam reforming process treated about 900 pounds (409 kilograms) of waste, reducing the hydrogen content of the waste to prevent explosive mixtures of hydrogen gas from forming in the storage capsules 116,301.

CONCLUSIONS All five of the innovative technologies discussed in

this paper are promising hazardous waste treatment or recycling technologies. Compared to rotary kiln incineration for example, which has been used for the treatment of hazardous wastes since 1948 [311, all five of the innovative technologies discussed in this paper are still in the early stages of commercial development. The technology with the most full-scale operational experience, Retech plasma, has been treating wastes since 1991. Table 1 summarizes the full-scale operational experience of the five technolo- gies.

All of these innovative technologies have relatively low waste throughput capacities. The waste through- put capacities range from 60 tons (55 tonnes) per

year for steam reforming to about 4,000 tons (3,636 tonnes) per year for plasma arc centrifugal treatment. Table 1 summarizes the throughput capacities of the five technologies. Because of these low waste throughput capacities, the operating costs of these technologies are relatively high when compared, for example, to a 60,000 ton (54,545 tonne) per year commercial hazardous waste incinerator. Conse- quently, four of these technologies have been used primarily in the radioactive and mixed waste market niches where waste disposal prices are higher than for RCRA and PCB wastes. The Eco Logic process is the only one of the five technologies to primarily treat PCB and RCRA hazardous wastes. Table 1 sum- marizes the full-scale waste treatment market niches for the five technologies.

There is very little published information available on operating costs or market prices for these technologies. In 1994, GTS Duratek was awarded a contract for $14 million to build the DuraTherm 5000 glass melter to treat 660,000 gallons (204 million liters) of radioactive sludge at the DOE’S Savannah River Site [321. Eco Logic has stated that its costs are $265 to $529 per ton ($292 to $582 per tonne) of soil and $1323 to $1654 per ton ($1,455 to $1,819 per tonne) for PCB contaminated oil and equipment [331.

In general, because of competitive pressures, devel- opers of innovative technologies are reluctant to make technology market prices public. Care must be taken in evaluating published costs because early contracts won by innovative technology companies are often won with bid prices that are below operating costs in order to obtain full-scale operating experience. In some cases, innovative technology developers will publish costs that are extrapolated to design throughput capacities even though the technology has not yet obtained these design capacities in full-scale operation.

The Retech plasma and GTS Duratek glass melter processes have an advantage over conventional treat- ment processes for radioactive wastes because these processes vitrify the radioactive constituents of the waste ash. In order to compete successfully long term in the United States hazardous waste and PCB disposal markets, these and other innovative technologies will need to continue to reduce their operating costs by improving their throughput capacities and their ability to treat sludges, drummed solids and bulk solid wastes.

Environmental Progress (Vol. 18, No.4) Winter 1999 291

LITERATURE CITED 1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14. 15.

16.

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National Research Council, “Review and Evalua- tion of Alternative Chemical Disposal Technolo- gies,” National Academy Press, Washington, D.C.. (1 996). Eli Eco Logic, Inc., “Technology Update,” Rock- wood, Ontario, Canada, Qanuary 1996). Kummling, B. and D. Gray, Eco Logic, Inc., per- sonal communication to J. Cudahy, Focus Environ- mental, Inc., (February 1 and March 10, 1999). “Australia’s World-Leading Solution for Hazardous Waste Destruction,” Australasian Pollution & Waste Management, Issue 6, pp 36-37 (1998) Eli Eco Logic, Inc., “Media Release”, Rockwood. Ontario, Canada, (February 9. 1996). Eli Eco Logic, Inc., 1996 annual report, page 1 Pegg, I., “MAWS: A Program for the Development and Demonstration of an Integrated, Multiple- Technology, Multiple-waste-stream Treatment Sys- tem for the Fernald Site,” Mixed Waste Proceed- ings, 2nd International Symposium, (1993). Cage, M., GTS Duratek, personal communication to J. Cudahy, Focus Environmental, Inc., (February 19, 1999).

(May 15, 1997).

292 Winter 1999

17. Davidson, Michael, I. Howard and W. Veronee, Jr., “Development and Implementation of a Site Radiation Protection Program for a Radioactive Waste Vitrification and RCRA Clean Closure Project at the Savannah River Site,” Proceedings of Waste Management 96, Tucson, AZ, (February 27, 19961.

18. Pope, J. and D. Macias, “Melter Replacement for M-Area Facility,” In Site, GTS Duratek Newsletter, 15, page 5, (First Quarter 1797).

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Fiivironmentzil Progress (Vol. 18, No.4)