Biomedical Engineering Reference
In-Depth Information
FIGURE 5.10
Schematic of a reactive biofilm barrier. Depending on the goal of the barrier
(reduction in permeability [groundwater flow] and degradation of contami-
nants or only degradation of contaminants but no hydraulic manipulation) a
different degree of permeability reduction, and thus biofilm growth, is desired.
The barrier can be established through the injection of nutrients (carbon
source, electron donor, electron acceptor, etc.) and bacteria (if necessary).
Contaminant transformation, sorption, and precipitation will all play a role
in the ultimate fate of the contaminants.
field situations. Zero-valent iron-based barriers are probably the most common
type of permeable subsurface barrier employed (Gould 1982; Cantrell et al.
1995; O'Hannesin and Gillham 1998; Fiedor et al . 1998; Scherer et al . 2000;
Wilkin et al . 2003), and the influence of attached microorganisms on their
performance has been noted (Gerlach et al . 2000; Gu et al . 2002; Shin et al .
2007). Furthermore, biologically active permeable reactive barriers for the
control and treatment of acidic mine wastewater have been proposed and
demonstrated in the field (Waybrant et al . 1998; Benner et al . 1999; Ludwig
et al . 2002; Golab et al . 2006; Davis et al . 2007). Chemical in situ redox
manipulation has also been demonstrated in situations where trench and fill
methods are impractical owing to depth limitations (Istok et al . 1999; Seaman
et al . 1999).
On the basis of the success and relative ease of implementation of these
technologies, combined with the possibility of establishing biologically active
zones in the deep subsurface through the careful control of distribution
and activity of microorganisms, the development of permeable subsurface
biofilm barriers has immense economical potential. Especially the possibil-
ity of employing such treatment strategies in the deep subsurface through the
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