Variation of soil hydraulic conductivity by anionic surfactants in soil column

Abstract

Remediation techniques using surfactants to flush hydrophobic organic contaminants from soils have recently been investigated. However, less attention has been given to evaluating the effects of surfactants on the hydraulic properties of porous media. The objective of this study was to investigate the effects on saturated hydraulic conductivity of the interactions between soil type (sand, clay loam) and anionic surfactants (DOSL, SLS, TDCA). Saturated hydraulic conductivities of two Iowa soils, Fruitfield sand and Webster clay loam, were measured in constant-head laboratory columns. The two soils were leached with solution of 4% (v/v) sodium diphenyl oxide disulfonate (DOSL, trade name Dowfax 8390) or 4% (w/v) sodium lauryl sulfate (SLS, trade name SLS) or 4% (v/v) trideceth-19-carboxylic acid (TDCA, trade name Sandopan JA36). As controls, soils were also leached with deionized water. Reductions in hydraulic conductivity due to surfactant leaching ranged from 9% to 85% relative to the initial values measured with deionized water. The most severe reductions in saturated hydraulic conductivity occurred in Webster soil leached with solution of TDCA. For three surfactants, more clogging occurred in the Webster clay loam than the Fruitfield sand. For both soils, the least clogging occurred with DOSL. Doubling the DOSL concentration to 8.2% did not change its effect on hydraulic conductivity for either soil. Results of this study suggest that the surfactant DOSL is a good candidate for surfactant-assisted remediation based on its relatively small effects on soil hydraulic conductivity. These results indicate that potential surfactant-assisted hydraulic conductivity losses should be considered prior to in-situ surfactant remediation.