Agriculture Reference
In-Depth Information
1600
Webster
1400
1200
1000
800
600
Initial Zn = 80 ppm
Initial Zn = 100 ppm
Initial Zn = 150 ppm
Sorption
Sorption simulated
Desorption simulated
400
200
Zn-Hysteresis (P = 0)
0
0
2
4
6
8
10
12
1600
Webster
1400
1200
1000
800
600
Initial Zn = 80 ppm
Initial Zn = 100 ppm
Initial Zn = 150 ppm
Sorption
Sorption simulated
Desorption simulated
400
200
Zn-Hysteresis (P = 100)
0
0
1
2
3
4
5
6
7
Zn Concentration (mg/L)
FIGURE 7.24
Adsorption and desorption isotherms for Webster soil with different P concentration. The
solid and dashed curves depict results of multireaction (MRM) model simulations for sorption
and desorption.
volumes, 55% of applied Zn was retained in the presence of P compared to
31% retention without P. Overall Zn concentration in the effluent decreased
in the presence of P without a change in the relative position of the BTC;
for example, arrival of the Zn front in the effluent solution. Such behavior
is indicative of increased irreversible Zn retention in the presence of P. It is
clear that the presence of P resulted in a lower peak concentration and less
overall Zn recovery in the effluent when compared to column 1 BTCs where
P was absent. The transport data are consistent with retention and clearly
indicate that the presence of P increases the amount of Zn sorbed. Moreover,
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