Experimental and Numerical Study of the Performance of Various Non‐Pumping Reactive Well Configurations for Iron Remediation in Groundwater

This study examines the performance of various configurations of non‐pumping reactive wells (NPRWs) using both experimental and numerical models. Six different NPRW configurations, including single, double, and staggered transects, arranged at well spacing of 11 and 16 cm, packed with 2:1 sawdust to sand reactive material, were examined in a sandbox with dimensions of 1.4 m × 0.4 m × 0.4 m under a 10 cm water head difference between upstream and downstream reservoirs. Experimental trials demonstrated that, in the case of 16 cm well spacing, arranging wells in a staggered pattern achieved the highest iron decontamination with a removal efficiency of 98.47%, compared to 93.76% for double transect and 91.87% for single transect. Conversely, under 11 cm well spacing, the single transect achieved a remarkable performance by achieving 97.3% removal efficiency, outperforming both staggered (95.35%) and double transect (93.90%), suggesting that excessive well density in complex NPRWs configurations may reduce removal effectiveness due to flow interference and limited interaction between the reactive material and the contaminated plume. Groundwater modeling using the MT3DMS model produced simulated results that align with the experimental results, confirming the superior plume attenuation represented by a staggered pattern across 16 cm spacing, while a clear discrepancy between experimental and numerical results is observed in the case of 11 cm spacing, highlighting the limitation of numerical models to real‐world heterogeneities and field constraints.