Acceleration of Groundwater Remediation by Rapidly Pulsed Pumping: Laboratory Column Tests

Groundwater contamination is expensive to remediate, primarily because of the treatment time required. Increased treatment time can be caused by several contributing factors, such as sequestration in low-permeability regions of an aquifer, which can cause tailing and rebound phenomena. One such region consists of dead-end pores. Once a contaminant enters the dead-end pores, it remains in an eddy and only moves back into well-connected pores, from which it can be advected away, by molecular diffusion. A previous study with computational fluid dynamics suggested that rapidly pulsed flow demonstrated the potential to accelerate contaminant removal from dead-end pores. Here, we tested the recovery of a dissolved contaminant under steady and rapidly pulsed flow from a porous media column with crushed glass, which should have naturally formed dead-end pores. This test simulated the fluid dynamics in a flow constrained by a column without sorption; therefore, this tested the dynamics in the dead-end pores but did not include the complete dynamics of a remediation scheme. The results showed accelerated removal under rapidly pulsed flow, which is consistent with results from the computational model; however, there may be additional or alternative sources of the sequestered contaminant.