Modeling for Surfactant-Enhanced Groundwater Remediation Processes at DNAPLs-Contaminated Sites

In this study, a numerical modeling technique for simulating surfactant-enhanced groundwater remediation processes is introduced. The model could not only examine the physicochemical behaviour of a multiphase system due to surfactant injection through considering balance equations for all phases, but also explain the solubilization and mobilization mechanisms for removing entrapped residual DNAPL due to introduction of surfactant solutions. The model is applied to a hypothetical PCE-contaminated site for simulating the surfactant-flushing process. The application indicates that, given some approximate information of initial PCE distribution and layering, surfactant-enhanced remediation can be simulated by the model to a reasonable degree of certainty. The modeling results show that the surfactant has the significant potential to improve remediation efficiency, reduce remediation time, and lower down remediation costs in comparison with conventional pump-and-treat remediation measure. This study demonstrates the model's capability in simulating the remediation processes and effectiveness in interpreting surfactant enhancement effect. It is indicated that modeling studies could not only help gain insights of the remediation processes but also provide scientific bases for decision and design of site-specific remediation plans.