Environmental Engineering Reference
In-Depth Information
1.2
1.0
0.8
0.6
Zone of
stagnant high
PWP for 28 days
Zone of
stagnant high
PWP for 28 days
0.4
0.2
34 hrs
143 hrs
397 hrs
83 hrs
203 hrs
866 hrs
6 hrs
118 hrs
250 hrs
0.0
0.0
0.2
0.4
0.6
0.8
1.0
Normalized distance from anode end, x/L
Figure 2.39 Spatial and temporal distribution of normalized pore water pressure (PWP)
between adjacent probes at select times during EK (Muraoka et al., 2011)
attributed to streaming potential and migrating fronts of ions in the high
salinity environment. The resistance to pore water pressure dissipation was
attributed to compression and polarization of particle DDL in the direc-
tion of the electric field. The combined consequence of these phenomena is
the competing pressure gradients that keep the clay particles from settling
and dewatering (Muraoka et al., 2011).
2.3.3 Electrokinetially-Aided Containment
Containment in this publication is defined as causing controlled accu-
mulation of a toxic substance by sorption in a small volume of substrate
(i.e., permeable barrier), which can be flushed and regenerated for further
use. Electrokinetic containment may be accomplished by causing electro-
migration or electroosmotic transport of the contaminants to a reactive
permeable barrier (Rael et al., 1995; Blowes et al., 1995), strategically sit-
uated between the electrodes, where they are attenuated and the filtered
water is allowed to pass through (Hansen, 1995; Weeks and Pamukcu,
1996). In actual field applications, such permeable structures could be
installed in multiples at various configurations throughout a contaminated
site serving as primary and secondary treatment locations.
Pre-contaminated kaolinite samples with lead, Pb(II) (from Pb(NO 3 ) 2
salt) were tested to determine the effectiveness of using permeable reactive
caps to contain heavy metals adjacent to the electrode chambers. The reac-
tive permeable caps (GS caps) were comprised of 50% glauconite (green
sand), 30% zeolite, and 20 % bentonite clay by mass. The average particle
 
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