Soil flushing of residual transmission fluid: Application of Colloidal Gas Aphron suspensions and conventional surfactant solutions

An innovative technology using Colloidal Gas Aphrons (CGAs) is applied in this study to flush residual levels of a light non-aqueous phase liquid (LNAPL) such as automatic transmission fluid (ATF) from a Superfund site soil. Performance of CGA suspensions is compared with that of conventional aqueous anionic surfactant solutions under both gravity stable (downflow) and gravity unstable (upflow) conditions. CGA suspensions were found to be more effective in washing ATF under both downflow and upflow modes. The displacement of ATF from the soil pores seems to be the mechanism of removal in the case of water floods. Increasing the surfactant concentration did not increase the removal rate correspondingly. The pressure required to pump the CGA suspension was much lower than that required for conventional surfactant solutions or water flood. Results show enough promise that more research should be directed at this potential technology for in situ remediation of contaminated aquifers.