Environmental Engineering Reference
In-Depth Information
site is 1.56. Thus, at a groundwater flow velocity of 1 m/a, TCE transported
is 0.64 m/a.
[
]
C
100
100
%×
K
org
oc
(4.1)
K
=
D
R =+
⎛
1K
D
×
ρ
θ
⎞
⎟
(4.2)
⎜
In the second model (model II, detailed model), the annular space of the
extraction well system at the tip of the plume was reproduced to scale, in
order to simulate passive remediation which occurs after the pumping has
ceased. For the reactive material Remat™, batch and column experiments
have been carried out by CRC CARE. As a result, adsorption isotherms and
breakthrough curves were provided by chemists at CERAR, University of
South Australia, and the results are considered in the model. Concerning
adsorption, the Freundlich isotherm gave the best correlation to the mea-
sured values and was used for the simulations as shown in Figure 4.4.
The column experimental study showed that the breakthrough curve of
TCE was a straight line over the entire trial. This indicates that the adsorption
process is controlled by kinetics and increases with time, and also that the
material being investigated has a very high capacity for retaining TCE. The
adsorption of TCE on Remat™ might be controlled by the slow diffusion of
the contaminant toward the inner surfaces of the organic material. We deter-
mined the adsorption parameters from the breakthrough curve using the
software Stanmod (Simunek et al., 1999). The two-site-nonequilibrium sorp-
tion model (Wagenet and Van Genuchten, 1989) fits the experimental points
best. The parameters used in the numeric simulations rather underestimate
2.5
ReMat20 Freudlich isotherms
2.4
y = 0.6659x + 0.3031
2.3
R
2
= 0.9621
2.2
2.1
2
1.9
2.5
2.6
2.7
2.8
Log C
e
2.9
3
3.1
FIGURE 4.4
Freundlich adsorption isotherm for ReMAT™ from batch experiments.
Search WWH ::
Custom Search