Persulfate Transport in Two Low-permeability Soils

by MARISSA C. MERKER, M.S.C.E. Washington State University August 2010 Chair: Richard J. Watts Persulfate is a promising in situ chemical oxidation treatment (ISCO) for the remediation of low-permeability strata because it is more stable in the subsurface and can rapidly degrade recalcitrant contaminants compared to other technologies. ISCO technologies include catalyzed hydrogen peroxide propagations (CHP), ozone, permanganate and persulfate treatments. Persulfate is a strong oxidant similar to CHP; however, it has a wider range of influence due to its longevity in the subsurface. Diffusion is the dominant mechanism of solute transport in finegrained, or low-permeability, soils and can be estimated mathematically with an analytical solution to Fick’s first or second law of diffusion. Knowledge of persulfate diffusion is important the remediation of fine-grained soils. The objective of this research was to use column studies to investigate the transport of persulfate in two low-permeability soils: kaolin and Palouse loess. Persulfate was detected in the kaolin throughout the column length (approximately 4 cm) after an 82 d testing period. For the Palouse loess columns, 1 M solution of persulfate was detected the length of approximately 12 cm over 70 d and the 0.1 M solution reached an approximate depth of 6-7 cm over 85 d. The transport of persulfate generally increased with concentration and time, despite decomposition.