Using colloidal deposition to mobilize immiscible contaminants from porous groundwater aquifers

Abstract:

More than 40% of the United States receives its drinking water from porous groundwater aquifers that are susceptible to contamination from industrial processes. The persistence of these contaminants after their initial introduction frequently requires cost- and energy-intensive specialized remediation techniques. Here, we present a simple remediation strategy; we find that injection of colloidal particles improves contaminant removal from a porous medium compared to ambient flow alone. Specifically, by tailoring colloidal properties and injection conditions, we find that particles deposit onto the solid surfaces of the porous medium, enhancing the local fluid pressure and pushing out trapped non-aqueous contaminants. We also develop a model to describe how changing permeability impacts mobilization and compare the model’s predictions to experimental results. Importantly, this approach avoids the need for repeated pumping and treatment, representing a major advancement in simplicity and cost over current approaches.