Comparative Assessment of Injection Strategies for Highly Concentrated Nano Fe/Cu Particles into Sand Columns

The transport of bimetallic nano-Fe/Cu particles through coarse sand-packed columns was investigatedsimulating particle transport under 25 injection strategy scenarios. The considered transport mechanisms included retention on and release from the solid grains, modeled by a dual-site advection-dispersion-deposition equation, and clogging of the porous medium. The transport kinetics and parameters used in this study were calibrated against experimental data, previously reported, and simulated using E-MNM1D. The influence of the injected particle concentration(2 to 12 g/l), flow rate (43.2 to 172.8 m/d), duration,and eventual alternation of injection and flushing periods was analyzed. The impact of each scenario was quantified in terms of particle mobility, porous medium clogging, water pressure, and uniformity of distribution of the particles in the porous medium.The results of this study indicate that, when injecting under conditions typical of a full-scale aquifer remediation, nanoparticle mobility and distribution are optimized and clogging is minimized by using high flow rates, low concentrations, and frequent injection steps without intermediate flushing.