Technical Applications Manager: ISCO
Dr. Brant Smith is the Technical Applications Manager for In Situ Chemical Oxidation (ISCO) technologies at PeroxyChem. With over 15 years of experience, Dr. Smith has designed and implemented numerous field applications and bench scale tests involving ISCO, in situ bioremediation, in situ chemical reduction, and metals stabilization. He has been an author on over 70 presentations at national and international conferences and his research have been published in journals including Environmental Science and Technology, Journal of Contaminant Hydrology, Environmental Toxicology and Chemistry, Journal of Environmental Science and Health, and Journal of Environmental Engineering. Dr. Smith has been a co-Principal Investigator for a research grant (ER-2132) awarded by through the Strategic Environmental Research and Development Program (SERDP) and is a chapter co-author for the book In Situ Chemical Oxidation for Groundwater Remediation (Siegrist, et al., 2011). Dr. Smith obtained a Bachelor's of Science with the majors of Civil and Environmental Engineering and Economics from Worcester Polytechnic Institute, and a Master of Science and Ph.D in Civil Engineering from Washington State University. He is a registered Professional Engineer in Washington State.
FLASH POSTER PRESENTATION
Treatment of 1,4-Dioxane Comingled with TCA and DCA Using Both Oxidative and Reductive Pathways
In situ chemical oxidation (ISCO) has been applied at thousands of sites to treat a wide assortment of environmental contaminants of concern. Part of ISCO's wide spread appeal is that research has shown that specific ISCO technologies including catalyzed hydrogen peroxide (i.e. Fenton's reagent) and certain types of activated persulfate will create both oxidative and reductive pathways. This has allowed these types of ISCO technologies to be able to treat contaminants including 1,1,1-trichloroethane (TCA) and carbon tetrachloride in addition to compounds that are typically degraded using the oxidative pathway such as BTEX, PAHs and chlorinated ethenes.
The industrial additive 1,4-dioxane is an example of a compound that is readily treated by ISCO using the oxidative pathway when either the hydroxyl and sulfate radical is generated. However, a common issue associated with treating 1,4-dioxane is that it is often comingled with compounds such as TCA or daughter products including dichloroethanes (DCA), both of which are primarily degraded using the reductive pathway.
While sodium persulfate has been applied at thousands of sites, potassium persulfate is new to North America having primarily been applied in Europe and Canada. The benefits of potassium persulfate are its low solubility allowing for extended persistence in the subsurface compared to sodium persulfate.
Activated potassium persulfate was selected for several studies as it was intended to be used as a permeable reactive barrier (PRB) to treat dilute contaminant plumes containing 1,4-dioxane comingled with TCA or DCA at multiple sites. Longevity tests showed potassium persulfate persisted for 65 pore volumes at 20 C and 180 pore volumes at 4 C. The rate of release of potassium persulfate was linear for most of this duration allowing prediction of PRB persistence of months to years depending upon aquifer temperature and linear groundwater velocity. The data also showed treatment of 1,4-dioxane to below the detection limits with any of the activators used. However, the TCA and DCA daughter products were only treated to below the detection limits when the reductive degradation pathway was created. Multiple compounds were used to create these reductive conditions including calcium peroxide and hydrated lime.