Effect of Persulfate Formulations on Soil Permeability

by MIAO YU, M.S. Washington State University August 2010 Chair: Richard J. Watts In situ chemical oxidation (ISCO) using persulfate is a promising technique for the remediation of soil and groundwater contaminants. Persulfate activated by iron (III)-EDTA or sodium hydroxide can accelerate the degradation of contaminants. However, in previous studies of ISCO remediation processes, the application of ISCO chemicals has been limited by low permeability zones. Three persulfate process conditions typically used in the field were used in laboratory studies to investigate the effect of unactivated and activated persulfate formulations on the permeability of a suite of subsurface solids. Column tests were conducted via a falling head permeameter for commercial silica sand and a flexible wall permeameter was used for kaolinite and two natural soils to quantify changes in hydraulic conductivity after the application of persulfate formulations. Unactivated persulfate and iron (III)-EDTA-activated persulfate had minimal effect on the permeability of all four soils. Base-activated-persulfate increased the permeability of kaolinite and the natural soils, but decreased the permeability of sand. Changes in soil dispersion, flocculation, and surface charge may have contributed to changes in soil permeability. X-ray computed tomography (XRCT) was used to investigate the effect of persulfate formulations