Environmental Engineering Reference
In-Depth Information
2500
Fig. 1.7
Uranium
accumulation in SRB biofilms
in reactors filled with various
minerals. The
continuous line
shows the cumulative amount
of uranium delivered to each
reactor (or maximum possible
uranium accumulation).
Modified from reference [87].
Reprinted with permission
from Marsili et al. [87].
Copyright 2007 American
Chemical Society
U(VI) delivered to the column
2000
1500
1000
Calcite
Dolomite
Hematite
500
0
0
50
100
150
Time (day)
periplasmic space. However, we do not currently know the quantitative contribution
of the EPS and the cells to uranium immobilization in biofilms.
Based on the results obtained, possible mechanisms contributing to U removal
by SRB biofilms grown on minerals have been proposed and are schematically
shown in Fig. 1.10. Although the figure shows biofilms grown on hematite only,
similar mechanisms should be active in biofilms grown on other redox-sensitive
surfaces, including calcite, dolomite and natural sediments. In U immobilization
using biofilms grown on Mn-bearing minerals, Mn(II) and Mn(IV) may have effects
similar to those of Fe(II) and Fe(III) (Fig. 1.11).
A
B
Fig. 1.8
TEM images of thin
cross sections of biofilms
deposited in the reactors filled
with (
a
) a redox-insensitive
surface, quartz, and
redox-sensitive surfaces: (
b
)
calcite, (
c
) dolomite and (
d
)
hematite. Reprinted with
permission from Marsili et al.
[87]. Copyright 2007
American Chemical Society
C
D
