Purpose Section 121(b) of the Comprehensive Environmental Re- sponse, Compensation, and Liability Act (CERCLA) mandates the Environmental Protection Agency (EPA) to select remedies that "utilize permanent solutions and alternative treatment technologies or resource recovery technologies to the maxi- mum extent practicable" and to prefer remedial actions in which treatment "permanently and significantly reduces the volume, toxicity, or mobility of hazardous substances, pollut- ants and contaminants as a principal element." The Engineer- ing Bulletins are a series of documents that summarize the latest information available on selected treatment and site remedia- tion technologies and related issues. They provide summaries of and references for the latest information to help remedial project managers, on-scene coordinators, contractors, and other site cleanup managers understand the type of data and site characteristics needed to evaluate a technology for poten- tial applicability to their Superfund or other hazardous waste site. Those documents that describe individual treatment tech- nologies focus on remedial investigation scoping needs. This document is an update of the original bulletin published in May 1991 [1].* Abstract Thermal desorption is an ex situ means to physically separate volatile and some semivolatile contaminants from soil, sediments, sludges, and filter cakes by heating them at temper- atures high enough to volatilize the organic contaminants. For wastes containing up to 10 percent organics or less, thermal desorption can be used in conjunction with offgas treatment for site remediation. It also may find applications in conjunc- tion with other technologies at a site. Thermal desorption is applicable to organic wastes and generally is not used for treating metals and other inorganics. The technology thermally heats contaminated media, gener- ally between 300 to 1,000°F, thus driving off the water, volatile contaminants, and some semivolatile contaminants from the contaminated solid stream and transferring them to a gas stream. The organics in the contaminated gas stream are then treated by being burned in an afterburner, condensed in a single- or multi-stage condenser, or captured by carbon ad- sorption beds. The use of this well-established technology is a site-specific determination. Thermal desorption technologies are the se- lected remedies at 31 Superfund sites [2]. Geophysical investi- gations and other engineering studies need to be performed to identify the appropriate measure or combination of measures to be implemented based on the site conditions and constitu- ents of concern at the site. Site-specific treatability studies may be necessary to establish the applicability and project the likely performance of a thermal desorption system. The EPA contact indicated at the end of this bulletin can assist in the identifica- tion of other contacts and sources of information necessary for such treatability studies. This bulletin discusses various aspects of the thermal desorption technology including applicability, limitations of its use, residuals produced, performance data, site requirements, status of the technology, and sources of further information. Technology Applicability Thermal desorption has been proven effective in treating organic-contaminated soils, sediments, sludges, and various filter cakes. Chemical contaminants for which bench-scale through full-scale treatment data exist include primarily volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), polychlorinated biphenyls (PCBs), pentachloro- phenols (PCPs), pesticides, and herbicides [1][3][4][5][6][7]. The technology is not effective in separating inorganics from the contaminated medium. Extremely volatile metals may be removed by higher temperature thermal desorption systems. However, the tem- perature of the medium produced by the process generally does not oxidize the metals present in the contaminated medium [8, p. 85]. The presence of chlorine in the waste can affect the volatilization of some metals, such as lead. Generally, as the chlorine content increases, so will the likelihood of metal volatilization [9]. * [reference number, page number] Printed on Recycled Paper ------- The technology is also applicable for the separation of organicsfrom refinery wastes, coal tar wastes, wood-treating wastes, creosote-contaminated soils, hydrocarbon- contaminated soils, mixed (radioactive and hazardous) wastes, synthetic rubber processing wastes, and paint wastes [4][1 0, Table 1 RCRA Codes for Wastes Treated by Thermal Desorption Performance data presented in this bulletin should not be considered directly applicable to other Superfund sites. A number of variables, such as concentration and distribution of contaminants, soil particle size, and moisture content, can all affect system performance. A thorough characterization of the site and well-designed and conducted treatability studies of all potential treatment technologies are highly recommended. Table 1 lists the codes for the specific Resource Conserva- tion and Recovery Act (RCRA) wastes that have been treated by this technology [4][10, p.7][11]. The indicated codes were derived from vendor data where the objective was to determine thermal desorption effectiveness for these specific industrial wastes. The effectiveness of thermal desorption on general con- taminant groups for various matrices is shown in Table 2. Examples of constituents within contaminant groups are pro- vided in 'Technology Screening Guide For Treatment of CERCLA Soils and Sludges" [8, p. 1 0]. This table has been updated and is based on the current available information or professional judgment where no information was available. The proven effectiveness of the technology for a particular site or waste does not ensure that it will be effective at all sites or that the treatment efficiencies achieved will be acceptable at other sites. For the ratings used for this table, demonstrated effectiveness means that, at some scale, treatability was tested to show the technology was effective for that particular contaminant and medium. The ratings of potential effectiveness or no expected effectiveness are both based upon expert judgment. Where potential effectiveness is indicated, the technology is believed capable of successfully treating the contaminant group in a particular medium. When the technology is not applicable or will likely not work for a particular combination of contaminant group and medium, a no expected effectiveness rating is given. Another source of general observations and average re- moval efficiencies for different treatability groups is contained in the Superfund Land Disposal Restrictions (LDR) Guide #6A, "Obtaining a Soil and Debris Treatability Variance for Remedial Actions," (OSWER Directive 9347.3-06FS, September 1990) [12] and Superfund LDR Guide #6B, "Obtaining a Soil and Debris Treatability Variance for Removal Actions," (OSWER Directive 9347.3-06BFS, September 1990) [13]. A further source of information is the U.S. EPA's Risk Reduction Engineering Laboratory Treatability Database (ac- cessible via ATTIC). Technology Limitations Inorganic constituents or metals that are not particularly volatile will unlikely be effectively removed by thermal desorp- tion. If there is a need to remove a portion of them, a vendor Wood Treating Wastes K001 Dissolved Air Flotation K048 Stop Oil Emulsion Solids K049 Heat Exchanger Bundles Cleaning Sludge K050 American Petroleum Institute (API) Separator Sludge K051 Tank Bottoms (leaded) K052 Table 2 Effectiveness of Thermal Desorption on General Contaminant Groups for Soil, Sludge, Sediments, and Filter Cakes Contaminant Croups o cT •tt e 1* 5 „ jj QC Halogenated volatiles Halogenated semivolatiles Nonhalogenated volatiles Nonhalogenated semivolatiles PCBs Pesticides Dioxins/Furans Organic cyanides Organic corrosives Volatile metals Nonvolatile metals Asbestos Radioactive materials Inorganic corrosives Inorganic cyanides Oxidizers Reducers Effectiveness Sedl- Filter Soil Sludge merits Cokes T G • G G G G G G G T • T T T T V T G V G G G G G G G T V V T • T V T G T G Q G G G G Q • • • • T T T T G T G G G G G G Q • Demonstrated E ffectiveness: Successful treatability test at some scale completed V Potential Effectiveness: Expert opinion that technology will work Q No Expected Effectiveness; Expert opinion that technology will not work process with a very high bed temperature is recommended due to the fact that a higher bed temperature will generally result in a greater volatilization of contaminants. If chlorine or another chlorinated compound is present, some volatilization of inorganic constituents in the waste may also occur [14, p.8]. The contaminated medium must contain at least 20 per- cent solids to facilitate placement of the waste material into the desorption equipment [3, p. 9]. Some systems specify a minimum of 30 percent solids [15, p. 6]. Engineering Bulletin: Thermal Desorption Treatment ------- As the medium is heated and passes through the kiln or desorber, energy is consumed in heating moisture contained in the contaminated soil. A very high moisture content may result in low contaminant volatilization, a need to recycle the soil through the desorber, or a need to dewater the material prior to treatment to reduce the energy required to volatilize the water. Material handling of soils that are tightly aggregated or largely clay can result in poor processing performance due to caking. Rock fragments or particles greater than 1 to 2 inches may have to be prepared by being crushed, screened, or shredded in order to meet the minimum treatment size. However, one advantage to soil preparation is that the con- taminated medium is mixed and exhibits a more uniform moisture and BTU content. If a high fraction of fine silt or clay exists in the matrix, fugitive dusts will be generated [8, p. 83], and a greater dust loading will be placed on the downstream air pollution control equipment [15, p. 6]. The treated medium will typically contain less than 1 percent moisture. Dust can easily form in the transfer of the treated medium from the desorption unit, but can be mitigated by water sprays. Normally, clean water from air pollution control devices can be used for this purpose. Some type of enclosure may be required to control fugitive dust if water sprays are not effective. Although volatile and semivolatile organics are the primary target of the thermal desorption technology, the total organic loading is limited by some systems to 10 percent or less [16, p. 11-30]. As in most systems that use a reactor or other equipment to process wastes, a medium exhibiting a very high pH (greater than 11) or very low pH (less than 5) may corrode the system components [8, p. 85]. There is evidence with some system configurations that polymers may foul or plug heat transfer surfaces [3, p. 9]. Laboratory/field tests of thermal desorption systems have docu- mented the deposition of insoluble brown tars (presumably phenolic tars) on internal system components [16, p. 76]. Caution should be taken regarding the disposition of the treated material, since treatment processes may alter the physical properties of the material. For example, this material could be susceptible to such destabilizing forces as liquefaction, where pore pressures are able to weaken the material on sloped areas or places where materials must support a load (i.e., roads for vehicles, subsurfaces of structures, etc.). To achieve or increase the required stability of the treated material, it may have to be mixed with other stabilizing materials or compacted in multiple lifts. A thorough geotechnical evaluation of the treated product would first be required [14, p.8]. There is also a possibility, that during the cleanup process at a particular site dioxins and furans may form and be released from the exhaust stack into the environment. The possibility of this occurring should be determined on a case-by-case basis. Technology Description Thermal desorption is a process that uses either indirect or direct heat exchange to heat organic contaminants to a tem- perature high enough to volatilize and separate them from a contaminated solid medium. Air, combustion gas, or an inert gas is used as the transfer medium for the vaporized compo- nents. Thermal desorption systems are physical separation processes that transfer contaminants from one phase to an- other. They are not designed to provide high levels of organic destruction, although the higher temperatures of some sys- tems will result in localized oxidation or pyrolysis. Thermal desorption is not incineration, since the destruction of organic contaminants is not the desired result. The bed temperatures achieved and residence times used by thermal desorption systems will volatilize selected contaminants, but usually not oxidize or destroy them. System performance is usually mea- sured by the comparison of untreated solid contaminant levels with those of the processed solids. The contaminated medium is typically heated to 300 to 1,000°F, based on the thermal desorption system selected. Figure 1 is a general schematic of the thermal desorption process. Material handling (1) requires excavation of the contam- inated solids or delivery of filter cake to the system. Typically, large objects (greater than 2 inches in diameter) are screened, crushed, or shredded and, if still too large, rejected. The material to be treated is then delivered by gravity to the desorber inlet or conveyed by augers to a feed hopper [6, p. 1 ]. Desorption (2) of contaminants can be effected by use of a rotary dryer, thermal screw, vapor extractor (fluidized bed), or distillation chamber [15]. As the waste is heated, the contaminants vaporize, and are then transferred to the gas stream. An inert gas, such as nitrogen, may be injected as a sweep stream to prevent contaminant combustion and to aid in vaporizing and remov- ing the contaminants [4][10, p. 1 ]. Other systems simply direct the hot gas stream from the desorption unit [3, p. 5][5]. The actual bed temperature and residence time are pri- mary factors affecting performance in the desorption stage. These factors are controlled in the desorption unit by using a series of increasing temperature zones [10, p. 1], multiple passes of the medium through the desorber where the operat- ing temperature is sequentially increased, separate compart- ments where the heat transfer fluid temperature is higher, or sequential processing into higher temperature zones [17][18]. Heat transfer fluids used include hot combustion gases, hot oil, steam, and molten salts. Offgas from desorption is typically processed (3) to re- move particulates that were entrained into the gas stream during the desorption step. Volatiles in the offgas may be burned in an afterburner, collected on activated carbon, or recovered in condensation equipment. The selection of the gas treatment system will depend on the concentrations of the Engineering Bulletin: Thermal Desorption Treatment ------- Clean Offgas 1 Excavation Material Handling (1) Desorption (2) ized Rejects Paniculate Removal/Gas Treatment System (3) Partic It ulates I Treated Medium -»*- S — ^- c c l ~^ \ 1 1 1 1 1 ^---1 Spent Carbon Concentrated Contaminants Water Figure 1 Schematic Diagram of Thermal Desorption contaminants, air emission standards, and the economics of the offgas treatment system(s) employed. Some methods commonly used to remove the particulates from the gas stream are cyclones, wet scrubbers, and baghouses. In a cyclone, particulates are removed by centrifugal force. In a wet scrub- ber, the contaminated gas stream passes upward through water sprays, causing the particulates to be washed out at the bottom of the scrubber. In a baghouse, particulates are caught by bags and discharged out of the system. Process Residuals Operation of thermal desorption systems may create up to six process residual streams: treated medium; oversized me- dium and debris rejects; condensed contaminants and water; spent aqueous and vapor phase activated carbon; particulate dust; and clean offgas. Treated medium, debris, and oversized rejects may be suitable for return onsite. The vaporized organic contaminants can be captured by condensation or passing the offgas through a carbon adsorp- tion bed or other treatment system. Organic compounds may also be destroyed by using an offgas combustion chamber or a catalytic oxidation unit [14, p.5]. When offgas is condensed, the resulting water stream may contain significant contamination depending on the boiling points and solubility of the contaminants and may require further treatment (i.e., carbon adsorption). If the condensed water is relatively clean, it may be used to suppress the dust from the treated medium. If carbon adsorption is used to remove contaminants from the offgas or condensed water, spent carbon will be generated, and is either returned to the supplier for reactivation/incineration or regenerated onsite [14, p.5]. Offgas from a thermal desorption unit will contain partic- ulates from the medium, vaporized organic contaminants, and water vapor. Particulates are removed by conventional equip- ment such as cyclones, wet scrubbers, and baghouses. Collect- ed particulates may be recycled through the thermal desorp- tion unit or blended with the treated medium, depending on the concentration of organic contaminants present on the particulates. Very small particles (<1 micron) can cause a visible plume from the stack [14, p.5]. When offgas is destroyed by a combustion process, com- pliance with incineration emission standards may be required. Obtaining the necessary permits and demonstrating compli- ance may be advantageous, however, since the incineration process would not leave residuals requiring further treatment. [14, p.5]. Site Requirements Thermal desorption systems typically are transported on specifically adapted flatbed semitrailers. Most systems consist of three components (desorber, particulate control, and gas treatment). Space requirements onsite are typically less than 150 feet by 150 feet, exclusive of materials handling and decontamination areas. Standard 440V, three-phase electrical service is needed. Water must be available at the site. The quantity of water needed is vendor- and site-specific. Treatment of contaminated soils or other waste materials require that a site safety plan be developed to provide for personnel protection and special handling measures. Storage should be provided to hold the process product streams until they have been tested to determine their acceptability for disposal or release. Depending upon the site, a method to store waste that has been prepared for treatment may also be necessary. Storage capacity will depend on waste volume. Onsite analytical equipment capable of determining the re- Engineering Bulletin: Thermal Desorption Treatment ------- sidual concentration of organic compounds in process residuals makes the operation more efficient and provides better informa- tion for process control. Performance Data Performance data in this bulletin are included as a general guideline to the performance of the thermal desorption technol- ogy and may not always be directly transferable to other Superfund sites. Thorough site characterization and treatability studies are essential in determining the potential effectiveness of the technology at a particular site. Most of the data on thermal desorption come from studies conducted for EPA's Risk Reduc- tion Engineering Laboratory under the Superfund Innovative Technology Evaluation (SITE) Program. Seaview Thermal Systems (formerly T.D.I. Services, Inc.) conducted a pilot-scale test of their HT-5 thermal desorption system at the U.S. DOE's Y-12 plant at Oak Ridge, Tennessee. The test was run to evaluate the capability of the unit to remove and recover mercury from a soil matrix. Initial mercury concen- trations in the soil were 1,140 mg/kg. The mercury was removed to concentrations of 0.19 mg/kg with a detection limit of 0.03 mg/kg. A full-scale cleanup (80 tons per day) using the HT-5 system, was conducted for Chevron U.S.A. at their El Segundo Refinery, The primary contaminants and their initial and final concentrations are indicated in Table 3 [20]. In September 1992, an EPA SITE demonstration was per- formed at a confidential Arizona pesticide site using Canonic Environmental's Low Temperature Thermal Aeration (LTTA®) system. The unit had a 35-ton-per-hour capacity. Approximate- ly 1,180 tons of pesticide-contaminated soil were treated during the demonstration over three 10-hour replicate runs. The primary pesticides were di(chlorophenyl) trichloroethane (DDT), di(chlorophenyl)dichloroethene (DDE), di(chlorophenyl) dichloroethane (ODD), and toxaphene. Concentrations of pesticides in contaminated soils ranged from 7,080 |ig/kg to 1,540,000 ^ig/kg. The LTTA® system obtained pesticide re- moval efficiencies ranging from 82.4 percent to greater than 99.9 percent. All pesticides, with the exception of DDE, were removed to near or below method detection limits in the soil. Table 4 presents a summary of four case studies involving full- scale applications of the LTTA® process [21]. An EPA SITE demonstration was performed at the Anderson Development Company (ADC) Superfund site in Adrian, Michi- gan using Roy F. Weston's Low Temperature Thermal Treatment (LT3®) system. The untt had a 2.1-ton-per-hour capacity. Approximately 80 tons of contaminated sludge were treated during the demonstration which consisted of six 6-hour repli- cate tests. The lagoon sludge was primarily contaminated with VOCsand SVOCs, including 4,4'-methylenebis(2-chloroaniline) (MBOCA). Initial VOC concentrations ranged from 35 to 25,000 pg/kg. In the treated sludge, VOC concentrations were below method detection limits (less than 30 ng/kg) for most compounds. MBOCA concentrations in the untreated sludge ranged from 43.6 to 960 ing/kg. The treated sludge ranged in concentration from 3 to 9.6 mg/kg. The LT3® system also decreased the concentration of all SVOCs present in the sludge, with two exceptions: chrysene and phenol. The increase of Table 3 Full-Scale Cleanup Results of the H-T-5 System [20] Feed Soil Concentration Contaminant (mg/kg) Toluene Benzene Ethylbenzene Xylenes Naphthalene 2-Methylnaphthalene Acenaphthlene Phenanthrene Anthracene Pyrene Benzo(a)Anthracene Chrysene Styrene 30 38 93 290 550 1400 57 320 320 38 36 45 13 Treated Soil Removal Contentration Efficiency (W/kg) (%) <620 <620 <620 <620 <620 <330 <330 <330 <330 <330 <330 <330 <620 <97.93 <98.36 <99.79 <99.78 <99.89 <99.98 <99.42 <99.90 <99.90 <99.13 <99.08 <99.27 <99.23 chrysene concentration was likely caused by a minor leak of heat transfer fluid. Chemical transformations during heating likely caused the phenol concentrations to increase. PCDDs and PCDFs were formed in the system, but were removed from the exhaust gas by the unit's vapor-phase carbon column with removal efficiencies, varying with congener, from 20 to 100 percent. Particulate concentrations in the stack gas ranged from less than 8.5 x 10"4 to 6.7 x 1O'3 grains per dry standard cubic meter (gr/dscm) and particulate emissions ranged from less than 1.2 x 10"4 to 9.2 x 10"4 pounds per hour. Table 5 presents a summary of three case studies involving pilot- and full-scale applications of the LT3® system [22]. In May 1991, an EPA SITE demonstration was performed at the Wide Beach Development site in Brand, New York using Soil Tech's Anaerobic Thermal Processor (ATP) system. Approxi- mately 104 tons of contaminated soil were treated during three replicate test runs. The soil and sediment at the site were primarily contaminated with PCBs, along with VOCs and SVOCs. The average total PCB concentration was reduced from 28.2 mg/kg in the contaminated soil and sediment to 0.043 mg/kg in the treated soil (a 99.8 percent removal efficiency). The test indicated that an average concentration of 23.1 ng/dscm of PCBs was discharged from the unit's stack to the atmosphere. The high PCB concentrations in the emissions may have been caused by low removal efficiencies in the unit's vapor phase carbon system, high particulate loadings (0.467 gr/dscm) in the stack, or a combination of the two. Low levels of dioxins and furans were present in the feed soil, but none were detected in the treated soils, baghouse fines, or the cyclone's flue gas. The 2,3,7,8-TCDD toxicity equivalents (TEQ) of the stack gas ranged from 0.0106 to 0.0953 ng/dscm [23]. In June 1991, an EPA SITE demonstration test was per- formed at the Waukegan Harbor Superfund site in Waukegan Harbor, IL. The site was primarily contaminated with PCBs, along with VOCs, SVOCs, and metals. Approximately 253 tons Engineering Bulletin: Thermal Desorption Treatment ------- Table 4 Full-Scale Cleanup Results of the LIT A* System [21] Site South Kearney McKin Ottati and Goss Cannon Bridgewater Former Spencer Kellogg Facility Volume/Mass Treated 16,000 tons 11,500 cubic yards 4,500 cubic yards 11, 300 tons 6,500 tons Primary Contaminant(s) Total VOCs SVOCs VOCs SVOCs 1, 1, 1 TCA TCE Tetrachloroethene Toluene Ethylbenzene Total Xylenes VOCs Total VOCs SVOCs Feed Soil Concentration (mg/kg) 308.2 0.7- 15 2.7- 3,310 0.44 - 1.2 12-470 6.5 - 460 4.9-1200 >87 - 3,000 >50 - 440 >170->1100 5.30b 5.42 0.15-4.7 Treated Soil Contentration (mg/kg) 0.51 ND- 1.0 <0.05a <0.33-0.51 <0.025 <0.025 <0.025 <0.025-0.11 <0.025 <0.025 -0.14 <0.025 0.45 0.042 - <0.39 Average concentration Maximum concentration Table 5 Full-Scale Cleanup Results of the LT3® System [22] Volume/Mass Site Treated Confidential 1,000 cubic feet Tinker AFB, OK 3,000 cubic yards Letterkenny Army Depot 7.5 tons Primary Contaminant(s) Benzene Toluene Xylene Ethylbenzene Napthalene PAHs Volatiles Semivolatiles Benzene Trichloroethene Tetrachloroethene Xylene Other VOCs Feed Soil Concentration 1 ppm 24 ppm 110 ppm 20 ppm 4.9 ppm 0.890 - <6ppm 18^/kg- 37,250 ^g/kg 90 ng/kg - 53,000 ng/kg 590 ppm 2,680 ppm 1,420 ppm 27,200 ppm 39 ppm Treated Soil Contentration 5.2 ppb 5.2 ppb <1.0 ppb 4.8 ppb <0.33 ppm <330 - 590 ppb 0.1 ng/L-2.3ng/L 6 ng/L - <500 jig/L 0.73 ppm 1.8 ppm 1.4 ppm 0.55 ppm BDL BDL Below detection limits Engineering Bulletin: Thermal Desorption Treatment ------- of contaminated soil were treated during four runs using Soil Tech's ATP thermal desorption system. The system used was a combination thermal desorption and dechlorination process. The average PCB concentration in the feed soil was 9,173 mg/ kg; the average final concentration was 2 mg/kg, which is a 99.98 percent removal efficiency. The concentration of PCBs in the stack gas was 0.834 ^ig/dscm (a 99.999987 percent removal efficiency). Tetrachlorinated dibenzofurans were the only dioxins and furans detected in the stack gas at an average concentration of 0.0787 ng/dscm. The total concentration of SVOCs in the feed soil was 61.8 mg/kg. In the treated soils SVOC concentrations totaled only 8.52 mg/kg; only two samples were identified below the detection limit. In the contaminated soil, VOC concentrations totaled 17 mg/kg; while in the treated soil the total was only 0.03 mg/kg. Concentrations of metals were approximately the same in both the contaminated and treated soil. This was because the unit does not operate at temperatures high enough to significantly remove metals. The pH of the soil rose from 8.59 in the contaminated soil to 11.35 in the treated soil. This was likely due to the addition of sodium bicarbonate used to reduce PCB emissions [23]. In May 1992, an EPA SITE demonstration was performed at the Re-Solve Superfund site in North Dartmouth, Massachu- setts using the Chemical Waste Management X*TRAX™ sys- tem. The unit had a capacity of 4.9 tons per hour. Approxi- mately 215 tons of contaminated soil were treated over a period of three duplicate 6-hour tests. The soil is primarily contaminated with PCBs, along with some oil and grease and metals. Initial PCB concentrations ranged from 181 to 515 mg/ kg. The PCB concentration in the treated soil was less than 1.0 mg/kg with an average concentration of 0.25 mg/kg (a 99.9 percent removal efficiency). PCDDs and PCDFs were not formed during the demonstration. Concentrations of oil and grease, total recoverable petroleum hydrocarbons, and tetra- chloroethane were reduced to below detectable levels. Metal concentrations were not reduced during the test. This was expected because the unit does not operate at temperatures high enough to significantly remove metals [24]. RCRA LDRs that require treatment of wastes to best dem- onstrated available technology (BOAT) levels prior to land disposal may sometimes be determined to be applicable or relevant and appropriate requirements for CERCLA response actions. Thermal desorption often can produce a treated waste that meets treatment levels set by BOAT but may not reach these treatment levels in all cases. The ability to meet required treatment levels is dependent upon the specific waste constit- uents, the waste matrix, and the thermal desorption system operating parameters. In cases where thermal desorption does not meet these levels, it still may, in certain situations, be selected for use at the site if a treatability variance establishing alternative treatment levels is obtained. Treatability variances are justified for handling complex soil and debris matrices. The following guides describe when and how to seek a treatability variance for soil and debris: Superfund LDR Guide #6A, "Obtaining a Soil and Debris Treatability Variance for Remedial Actions" (OSWER Directive 9347.3-06FS, September 1990) [12], and Superfund LDR Guide #6B, "Obtaining a Soil and Debris Treatability Variance for Removal Actions" (OSWER Directive 9347.3-06BFS, September 1990) [13]. Technology Status Several firms have experience in implementing this tech- nology. Therefore, there should not be significant problems of availability. The engineering and configuration of the systems are similarly refined, so that once a system is designed full-scale, little or no prototyping or redesign is generally required. An EPA SITE demonstration took place at the end of 1993 at the Niagara Mohawk Power Corporation site in Utica, New York. The facility is a former gas manufacturing plant. Approxi- mately 800 tons of contaminated soils were treated during the demonstration. The soil is primarily contaminated with polyaromatic hydrocarbons (PAHs); benzene, toluene, ethylbenzene, and xylenes (BTEXs); lead; arsenic; and cyanide. An EPA Innovation Technology Evaluation Report will be de- veloped to evaluate the performance of and the cost to implement the system. Thermal desorption technologies are the selected reme- dies at 31 Superfund sites. Table 6 presents the status of selected Superfund sites employing the thermal desorption technology [2], Several vendors have experience in the operation of this technology and have documented processing costs per ton of feed processed. The overall range varies from approximately $100 to $400 (1993 dollars) per ton processed. Caution is recommended in using costs out of context because the base year of the estimates varies. Costs also are highly variable due to the quantity of waste to be processed, terms of the remedia- tion contract, moisture content, organic constituency of the contaminated medium, and cleanup standards to be achieved. Similarly, cost estimates should include such items as prepara- tion of Work Plans, permitting, excavation, processing, QA/QC verification of treatment performance, and reporting of data. EPA Contacts Technology-specific questions regarding thermal desorp- tion may be directed to: Paul dePercin U.S. Environmental Protection Agency Risk Reduction Engineering Laboratory 26 W. Martin Luther King Drive Cincinnati, Ohio 45268 (513)569 7797 James Yezzi U.S. Environmental Protection Agency Risk Reduction Engineering Laboratory Releases Control Branch 2890 Woodbridge Avenue Building 10(MS-104) Edison, Nj 08837 •7 Engineering Bulletin: Thermal Desorption Treatment ------- Selected Superfund Sites Specifying ThermS Desorption as the Remediation Technology [2] . — VOCs (Benzene, TCE, Toluene, McKin il Jfctati & Goss ifj 'Wide Beach Development f ^tetaltec/Aerosystems rCaJdwell Trucking McKin, ME (1) New Hampshire (1) Brandt, NY (2) Franklin Borough, N) (2) Fairfield, N] (2) VOCs (TCE, BTX) Site remediated 2/87 VOCs, (TCE, PCE, 1,2-DCE, Benzene) Site remediated 9/89 hQutboard Marlne/Waukegan Harbor Waukegan Harbor, IL (5) PCBs VOCs (TCE) VOCs (TCE, PCE, TCA) PCBs Dover Township, NJ (2) VOCs (TCE, PCE, TCA), SVOCs North Dartmouth, MA (1) PCBs Site remediated 6/92 Design completed Design completed Site remediated 6/92 Pre-design Pilot study completed 5/9 New Jersey (2) Burton, SC (4) Fulton, NJ (2) Adrian, Ml (5) VOCs (TCE, PCE), Metals (Cadimum, Design completed Chromium) VOCs, BTX VOCs (Xylene, TCE, Benzene, DCE) VOCs, SVOCs In design In design Site remediated 12/92 Anderson Development Company •••"••••••^ The two Stauffer Chemical sites in Table 10 of the original Engineering Bulletin are not included in this table because EPA's Ine ^w •*au'T .. „__„ tu.»... ,i ^.orrrtinn u/iil no onocr be molemented aunerCnemcal sites in laoie iuui uieuiiyn.a, u,-a».—-^ --..—.---- al Report indicates that thermal desorption will no longer be implemented (908)321-6703 ,f This updated bulletin was prepared for the U.S. Environ- mental Protection Agency, Office of Research and Develop- tnent (ORD), Risk Reduction Engineering Laboratory (RREL), Cincinnati Ohio, by Science Applications International Corpo- nfon (SAIQ under Contract No. 68-CO-0048. Mr. Eugene Harris served as the EPA Technical Project Monitor. Mr. Jim lUwe(SAIC) was the Work Assignment Manager. He and Mr. %fc Saytor (SAIQ co-authored the revised bulletin. The authors are especially grateful to Mr. Paul dePercin of EPA-RREL, who loiltributed significantly by serving as a technical consultant during the development of this document. The authors also f|pwnt to acknowledge the contributions of those who partici- pated in the development of and are listed in the original bulletin. The following other contractor personnel have contrib- uted their time and comments by participating in the expert review of the document: Mr. William Troxler Focus Environmental, Inc. Dr. Steve Lanier Energy and Environmental Research Corp. Engineering Bulletin: Thermal Desorption Treatment ------- REFERENCES 6. 7. Thermal Desorption Treatment. Engineering Bulletin. U.S. Environmental Protection Agency, EPA/540/2-91/ 008, May 1991. Innovative Treatment Technologies. Semi-Annual Status Report (Fourth Edition), U.S. Environmental Protection Agency, EPA/542/R-92/011, October 1992. Abrishamian, Ramin. Thermal Treatment of Refinery Sludges and Contaminated Soils. Presented at American Petroleum Institute, Orlando, Florida, 1990. Swanstrom, C, and C. Palmer. X*TRAX™ Transportable Thermal Separator for Organic Contaminated Solids. Presented at Second Forum on Innovative Hazardous Waste Treatment Technologies: Domestic and Interna- tional, Philadelphia, Pennsylvania, 1990. Canonic Environmental Services Corp. Low Temperature Thermal Aeration (LTTA®) Marketing Brochures, circa 1990. VISITT Database, U.S. Environmental Protection Agency, 1993. Nielson, R., and M. Cosmos. Low Temperature Thermal Treatment (LT3®) of Volatile Organic Compounds from Soil: A Technology Demonstrated. Presented at the American Institute of Chemical Engineers Meeting, Den- ver, Colorado, 1988. Technology Screening Guide for Treatment of CERCLA Soils and Sludges. U.S. Environmental Protection Agency, EPA/540/2-88/004, 1988. Considerations for Evaluating the Impact of Metals Parti- tioning During the Incineration of Contaminated Soils from Superfund Sites. Superfund Engineering Issue. U.S. Environmental Protection Agency, EPA/540/S-92/014, September 1992. 10. T.D.I. Services. Marketing Brochures, circa 1990. 11. Cudahy, j., and W. Troxler. 1990. Thermal Remediation Industry Update - II. Presented at Air and Waste Man- agement Association Symposium on Treatment of Con- taminated Soils, Cincinnati, Ohio, 1990. 12. Superfund LDR Guide #6A: (2nd Edition) Obtaining a Soil and Debris Treatability Variance for Remedial Ac- tions. Superfund Publications 9347.3-06FS, U.S. Envi- ronmental Protection Agency, 1990. 13. Superfund LDR Guide #6B: Obtaining a Soil and Debris 8. 9. Treatability Variance for Removal Actions. Superfund Publications 9347.3-06BFS, U.S. Environmental Protec- tion Agency, 1990. 14. Guide for Conducting Treatability Studies under CERCLA: Thermal Desorption Remedy Selection, In- terim Guidance. U.S. Environmental Protection Agency, EPA/540/R-92/074A, September 1992. 15. Recycling Sciences International, Inc., DAVES Marketing Brochures, circa 1990. 16. The Superfund Innovative Technology Evaluation Pro- gram- Progress and Accomplishments Fiscal Year 1989, A Third Report to Congress. U.S. Environmental Pro- tection Agency, EPA/540/5-90/001, 1990. 17. Superfund Treatability Clearinghouse Abstracts. U.S. Environmental Protection Agency, EPA/540/2-89/001, 1989. 18. Soil Tech, Inc. AOSTRA - Taciuk Processor Marketing Brochure, circa 1990. 19. Ritcey, R., and F. Schwartz. Anaerobic Pyrolysisof Waste Solids and Sludges - The AOSTRA Taciuk Process System. Presented at Environmental Hazards Confer- ence and Exposition, Seattle, Washington, 1990. 20. Seaview Thermal Systems. Marketing Brochures, circa 1993. 21. Low Temperature Thermal Treatment Aeration (LTTA®) Technology. Canonic Environmental Services Corpora- tion. Applications Analysis Report, U.S. Environmental Protection Agency (Draft-March 1993). 22. Roy F. Weston, Inc. Low Temperature Thermal Treat- ment (LT3®) System. Applications Analysis Report. Anderson Development Company Site. U.S. Environ- mental Protection Agency, EPA/540/AR-92/019, Decem- ber 1992. 23. Soil Tech ATP Systems, Inc. Anaerobic Thermal Proces- sor. Applications Analysis Report. Wide Beach Develop- ment Site and Outboard Marine Corporation Site. U.S. Environmental Protection Agency (Preliminary Draft- February 1993). 24. X*TRAX™ Model 200 Thermal Desorption System. Chemical Waste Management, Inc. Demonstration Bul- letin, U.S. Environmental Protection Agency, EPA/540/ MR-93/502, February 1993. Engineering Bulletin: Thermal Desorption Treatment .S. GOVERNMENT PRINTING OFFICE: 19*4 - 550-0*7/80195 ------- |