Senior Vice President, Director of Quality Control
EA Engineering, Science, and Technology, Inc., PBC
Dr. Barranco is Senior Vice President and Director of Quality Control of EA Engineering, Science, and Technology, Inc., PBC, located in Hunt Valley, Maryland. He has a B.S. in Geology from Duke University, an M.S. in Geology from University of Texas Arlington, and a Ph.D. in Environmental Science and Engineering from The Colorado School of Mines. His professional focus relates to contaminant fate and transport in groundwater, source area and groundwater cleanup of chlorinated solvents and other DNAPLs, and innovative in situ and ex situ cleanup of traditional and emerging contaminants. Dr. Barranco has worked with federal, municipal, and commercial clients across the country, directing work and serving in an engineering capacity on the assessment and remediation of hydrocarbon impacts to groundwater, soil, and fractured bedrock.
Evaluation of Indirect Thermal Desorption Coupled with Thermal Oxidation (ITD/TO) Technology to Treat Solid PFAS-impacted Investigation-Derived Waste (IDW)
Previous studies have shown that thermal technology (including Indirect Thermal Desorption [ITD]) can reduce PFAS levels in soil, combust PFAS contained in commercial products or mineralize PFAS-based industrial chemicals. However, uncertainties remain regarding ITD parameterization for application to treatment of specific PFAS-impacted waste as well as the destruction removal efficiency (DRE) that can be achieved through off-gas treatment by thermal oxidation (TO). The overall objective of this study was to advance the current understanding of ITD/TO’s effectiveness for the treatment of soil containing a typical suite of PFASs found in, but not limited to, Aqueous Film Forming Foam (AFFF) formulations manufactured and heavily utilized prior to 2002. During this study two phases of thermal treatment were evaluated to determine destruction efficiencies with respect to PFAS. Phase 1 treatment consisted of a pilot-scale thermal desorption unit used to treat PFAS-spiked soils and AFFF-spiked soils at two different temperatures (500°C and 650°C). Phase 2 treatment consisted of the TO operating at 1000°C to treat off-gas emissions from the ITD unit. A series of ten tests were conducted on sand spiked with PFAS compounds at concentrations ranging from approximately 6,000 to 19,000 micrograms per kilogram (ug/kg). Spiked feed soil samples and thermally treated soil samples were collected for each test run. All of the soil samples were analyzed for PFAS using EPA Method 537. For the test runs spiked with AFFF, soil samples were also analyzed for Total Oxidizable Precursor Assay (TOP). On four of the ten tests, the air from the thermal desorption unit was passed through a TO operating at a nominal temperature of 1000°C and air samples were collected from the exhaust gas. Four comparative test runs were conducted with two test runs analyzing the TO exhaust gas for PFAS compounds via EPA Method 0010/Method 537 and two test runs analyzing the exhaust gas for Hydrogen Fluoride (HF) via EPA Method 26A. The demonstration tests show conclusively that at 650°C the ITD technology will remediate PFAS in soil to a concentration of less than 1 to 10 micrograms per kilogram, and that a TO can achieve a DRE of greater than 99.9997% for off-gas emissions from ITD- treated PFAS feed material. Test results also demonstrated that ITD technology effectively desorbs PFAS precursors when treating AFFF-contaminated soils. The knowledge of how PFAS behaves in combustion or thermal processes is scarce. One of the more important aspects of this study was to advance the understanding of ITD/TO’s (at the temperatures tested) capability to achieve “irreversible destruction” of PFAS containing materials (including IDW) and if other unintentional degradation products may have been formed during the process. During the tests where the TO was used and the exhaust gas was analyzed for PFAS compounds and HF, a mass balance was performed on fluorine to demonstrate/confirm the destruction of the PFAS compounds. The extremely low detection of PFAS in the treated exhaust at (part per trillion levels and F mass balance confirmed the destruction of PFAS compounds.