The performance of cyclodextrin (CD)-enhanced push-pull (PP) and line-drive (LD) approaches to remediation of a site contaminated with a multicomponent dense nonaqueous phase liquid (DNAPL) present in a surficial sandy aquifer was evaluated in this field study. The treatment techniques were compared to each other and to the projected performance of a conventional water-flushing system. Performance was assessed based on contaminant mass removed per unit volume of extraction solution and per unit time of operation. As expected, the CD-enhanced LD and PP approaches to remediation were more efficient than conventional flushing with water. Between the two techniques, the PP approach performed 1.5 to 2 times better than the LD approach, particularly for higher DNAPL saturation of the source zone. This result suggests that forcing the flushing solution directly into and through the DNAPL source zone minimized flow bypassing and consequently resulted in a more efficient transfer of contaminant mass between the DNAPL phase and the flushing solution. Nonuniform treatment zone contaminant concentrations and changes in contaminant composition influenced the treatment performances, but these effects were small and still permitted the comparison of successive tests. Although CD was used as the solubility-enhancing flushing agent in this study, it is likely that the results can be transferred to other chemically enhanced flushing technologies that use, for example, surfactants or alcohols.
ASJC Scopus subject areas
- Water Science and Technology