VOC removal from contaminated groundwater through membrane pervaporation. (II): 1,1,1-trichloroethane-SDS surfactant...

The conventional "pump-and-treat" technology for subsurface remediation of groundwater contaminated with volatile organic compounds (VOCs) such as 1,1,1-trichloroethane (TCA), a common chlorinated organic solvent, has limitation of prohibitively long treatment time due to extremely low water solubility of the VOCs. Surfactant-based soil remediation has emerged as the effective technology that substantially reduces the treatment time. In order to make the whole process economical, the surfactant used in soil washing has to be recovered and reused. This study examined the recovery of anionic surfactant, sodium dodecyl sulfate (SDS), from soil remediation fluids containing TCA, using a bench-scale membrane pervaporation unit. The effects of high TCA concentration, surfactant dosage, and flow rate on permeation flux and selectivity (alpha value) of the process were evaluated. In general, higher surfactant concentration yielded lower TCA flux and constant water flux, resulting in declining a values; higher flow rate of TCA feed stream results in higher VOC flux and selectivity, an indication of the effect of concentration polarization; higher TCA feed concentration produces higher TCA permeation across the membrane, however, the selectivity was virtually unchanged unless the total TCA concentration exceeded 2000 ppm.