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SITE TECHNOLOGY CAPSULE: TERRA-KLEEN SOLVENT EXTRACTION TECHNOLOGY
Citation:
Engle, S. SITE TECHNOLOGY CAPSULE: TERRA-KLEEN SOLVENT EXTRACTION TECHNOLOGY. EPA/540/R-94/521a (NTIS 95-213617), 1995.
Impact/Purpose:
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Description:
Remediation of PCBs in soils has been difficult to implement on a full-scale, cost-effective basis. The Terra-Kleen solvent extraction system has overcome many of the soil handling, contaminant removal, and regulatory restrictions that have made it difficult to implement a cost-effective PCB soil treatment system. The Terra-Kleen system is a batch process that operates at ambient temperatures and removes organic contaminants from soils using proprietary solvents. After soils are washed with solvent, contaminated solvent passes through a recovery unit, where contaminants are separated from the solvent and concentrated, reducing the contaminant volume for disposal. The reclaimed solvent is then reused in the process. Terra-Kleen demonstrated the technology during a treatability study in October 1993 and a pilot-scale demonstration in June 1994. The demonstrations were conducted by the EPA SITE Program with the assistance of PRC Environmental Management, Inc. (PRC). In October 1993, the SITE Program obtained 1-ton batches of soil from each of 3 PCB-contaminated sites and shipped the soil to Terra-Kleen’s testing facility in Okmulgee, OK. Soils were obtained from Sites 4 and 6 at NASNI near San Diego, California, and from a third site in Anchorage, Alaska. Analyses of all demonstration soils revealed that Aroclor 1260 was the only PCB mixture present. Successful removal of PCBs during the treatability study led to a pilot-scale demonstration at NASNI in June 1994. The Naval Environmental Leadership Program (NELP) contracted TerraKleon to treat 5 tons of soil from Site 4 at NASNI. An agreement between the SITE Program and NELP was also established to help implement the pilot-scale demonstration. The primary objective of both the treatability study and pilot- scale demonstration was to determine the Terra-Kleen technology’s effectiveness at removing PCBs from soil. The target treatment level for system evaluation was the Toxic Substance Control Act’s (TSCA) incineration equivalency performance guidance level of 2 milligrams per kilogram (mg/kg) of PCBs in soil. PCB removal from soils and solvent was documented using on-site and off-site analytical tests. During the treatability study, soil was analyzed on site for PCBs using enzyme immunoassay (EIA) test kits, and during the pilot-scale demonstration using an on-site gas chromatograph (GC) with an electron capture detector. These analytical procedures permitted rapid (1-hr) evaluation of system performance dLring treatment. Split samples of untreated soil, treated soil, and regenerated solvent were sent to an off-site laboratory to confirm the system’s performance. PCB concentrations in untreated soils for both demonstrations ranged from 17 to 640 mg/kg. The removal efficiency for both tests ranged from 95% to 99%. Treated soil concentrations for the NASNI Site 4 demonstration were consistently below 2 mg/ kg. Only off-site laboratory data were reported, as these were subjected to the more stringent quality control review specified in the project quality assurance project plan. The Terra-Kleen solvent extraction technology was evaluated based on the nine criteria used for decision making in the Superfund feasibility study process. Results of the evaluation are summarized in Table 1. Under current TSCA regulations, only incinerators and Resource Conservation Recovery Act (RCRA) subtitle C-certified landfills have been permitted to dispose of PCB-contaminated soils. The SITE demonstration successfully demonstrated the Terra-Kleen system’s ability to reduce the PCB concentration in soils to less than 2 mg/kg in accordance with EPA TSCA guidelines. The EPA Office of Pollution Prevention and Toxics (administrative authority for TSCA) is reviewing Terra-Kleen’s permit application to treat PCB-contaminated soils. TSCA permit approval will enable Terra-Kleen to operate at RCRA, CERCLA, and private sites to remediate PCB-contaminated soils and provide owners of sites with an alternative to conventional disposal options. Development of the Terra-Kleen system has continued into full- scale remedial operations. A full-scale system began operating in July 1994 on DDT-contaminated soils at NCS-Stockton. Information on full-scale operations and the evaluation of demonstration results will be published in the Innovative Technology Evaluation Report (ITER), which will be available from EPA.