Optimal Initial Configuration of Treatment Solution for In Situ Remediation of Contaminated Groundwater Using Engineered Injection and Extraction

Groundwater constitutes about 30 percent of the available freshwater on earth; however, it is often contaminated by industrial or agricultural sources. The efficiency of current groundwater remediation methods must be improved, especially given that global consumption of water and energy continues to rise. During in situ remediation, a treatment solution (often a chemical oxidant) is injected into the contaminated aquifer to degrade the groundwater contaminant. Simulations have shown that spreading of treatment solution through a series of engineered injection and extractions (EIE) of clean water at wells surrounding the contaminated region increases the contact area between the treatment solution and contaminant, thereby enhancing contaminant degradation reactions. Previous studies have evaluated the amount of reaction during EIE in simulations where the initial injection of treatment solution was modeled as a circular, filled plume. This study alters the initial configuration of treatment solution by injecting clean water at the center of the treatment solution plume to produce a donut-shaped plume; thereby reducing the total quantity of treatment solution that is used. An optimal initial radius of the interior clean water plume that minimizes the amount of treatment solution injected and maximizes the amount of contaminant degraded is determined. As conservation of materials is important to any engineering project, this study also evaluates the trade-off between the cost of treatment solution and the impact of less contaminant degradation, as the interior clean water plume increases.