Dr. David Major, Ph.D., BCES, is the Managing Director of Savron, a division of Geosyntec Consultants, Inc, and Associate Editor of Ground Water Monitoring and Remediation. He has helped develop and commercialize remediation technologies such as zero-valent iron (ZVI) permeable reactive barriers, molecular biomarkers, bioaugmentation cultures, and currently Savron’s smouldering-based combustion technology (STAR). Dr. Major has served on various national scientific advisory boards including the U.S. EPA Expert Panel on DNAPL Remediation (The DNAPL Remediation Challenge: Is There a Case for Source Depletion), and the U.S. National Research Council Committee on Geological and Geotechnical Engineering in the New Millennium. He has co-developed and taught ITRC course on monitored natural attenuation, accelerated bioremediation, and bioremediation of DNAPLs. He has received several awards including: University of Waterloo Faculty of Science Alumni of Honour Award (2007) in recognition of his professional accomplishments; Space Hall of Fame® (2007) for helping NASA commercialize “Products from Space Benefiting Planet Earth”; ASTM C.A. Hogentogler Award (2015) and ICE Telford Premium (2016) awards for papers on ground improvement technology. He can be reached at Savron, 130 Stone Road West, Guelph, Ontario, N1G3Z2, (519) 515-0860, and by email at firstname.lastname@example.org.
A Smoldering Solution to PFASDavid Major (Savron, Guelph, ON, Canada), Alexandra Duchesne, Josh Brown, Jason Gerhard, Josh Brown (University of Western Ontario, London, ON, Canada), David Patch, Kela Weber (Royal Military College of Canada), David Reynolds (Geosyntec Consultants International), and Gavin Grant (Savron, Guelph ON, Canada)
A study conducted under the US Department of Defense (DoD) Strategic Environmental Research Program (SERDP) explored the application of smoldering combustion (STAR) to treat per- and polyfluoroalkyl substances (PFAS)-impacted soils and media.
Smoldering combustion is a low-cost / low-energy thermal technique for the treatment of contaminated soils. This approach is commercially available as the STAR (in situ), and STARx (ex-situ) technologies and is ideally suited to the treatment of heavy hydrocarbons. The process is self-sustaining following a short duration, low energy input ‘ignition event’ for low volatility, high energy compounds such as petroleum hydrocarbons. The energy that is released pre-heats and combusts contaminants in the adjacent area. Providing a constant supply of air will cause the self-sustaining combustion front to propagate vertically upward through the contaminated media. PFAS are not contaminants that can support smoldering combustion in and of themselves, and their high thermal stability requires temperatures greater than 900°C for them to start to decompose. Therefore, surrogate fuel is required. We explored the use of granular activated carbon (GAC) as a surrogate fuel source because it is often a by-product of water treatment and can contain PFAS. This study examined treating: (1) PFAS-impacted soils amended with a surrogate fuel (GAC); (2) PFAS-impacted liquid by absorbing the PFAS in the liquid to solid surrogate fuel (e.g., GAC); and, (3) co-treatment of PFAS contaminated soils with PFAS containing GAC.
Tests established that the addition of GAC at relatively low amounts to sand created smoldered at temperatures higher than 900°C. Post-treatment concentrations of PFAS in the remaining sand, soil, and ash were below detection limits (0.05 µg/kg). Initial emission analysis indicated the release of fluorine as HF with only small amounts of PFAS emitted, which could be subsequently captured by activated carbon and treated. Results to date are promising, suggesting STARx may provide an effective remediation technique for PFAS-impacted soils and IDW.