speed decreases with increasing distance from the borehole (Strutz et al. 2016). The
relationship is hyperbolic in the radial direction (Fig. 30.4). Thus, a column with a
constant transport rate of the suspension does not simulate the conditions of a real
application. Therefore, a column with gradual flow rate reduction (cascade) was
designed to at least partially simulate the decrease in the speed of the injected nZVI
suspension. The connection with a real situation is demonstrated in Fig. 30.5.
The radial zone is divided into defined layers, with each layer is approximated by
one section of column with a constant flow. A cascade column allows performing the
entire measurement continuously by achieving a gradual reduction in the flow rate in
defined column sections.
Fig. 30.4 Decrease in
migration speed with
increasing distance from the
well (radius of the well
5 cm, pore speed on the shell
of the well 100 m/24 h)
Fig. 30.5 Schematic interpretation of the cascade column related to the situation in the treated area.
1—application well, 2—profile of the collector simulated by the cascade column, 3—decreasing
migration speed with increasing distance from the well
30 Tool I: Characterization of nZVI Mobility in 1D and Cascade. . .
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