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In Situ
Biogeochemical Stabilization ( ISBS ) with
RemOx® EC Stabilization
Reagent
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The efficiency and costs
associated with the remediation of both dense non
aqueous phase liquids (DNAPL) and light nonaqueous
phase liquids (LNAPL) have been a long-standing
environmental remediation challenge. Some of
the technologies currently being used to recover or
destroy (NAPL) nonaqueous phase liquids include thermal-enhanced recovery,
surfactant flooding, and steam-and temperature-enhanced
extraction, and others. Experience shows that the
effectiveness of NAPL removal is site-dependent
and inversely related to NAPL saturation.
Saturations decline with each gallon of NAPL removed
from the formation until their residual saturation
is reached where, by definition, NAPLs can no longer
flow to a well or trench. Although some
technologies may be capable of recovering a small
percentage of the residual NAPLs, it is technically
and often economically impractical to recover a
significant percentage of the remaining NAPL.
An alternative to residual NAPL recovery is in
situ NAPL management. In situ
biogeochemical stabilization (ISBS) involves the use
of RemOx® EC Stabilization Reagent, a
proprietary permanganate solution, that is flushed through an
aquifer zone containing residual NAPLs. RemOx®
EC is different than standard in situ
chemical oxidation (ISCO) because the oxidant is not
meant to chemically remove the NAPL mass entirely.
Rather, the oxidant migrates through the targeted
source area where (bio)geochemical reactions
occur between both organic and inorganic constituents of
concern (COCs). The oxidant causes the
destruction and stabilization of NAPL via a two-step process: i) limited oxidation and ii)
encapsulation. The biogeochemical oxidation
process destroys COCs present in the dissolved
phase, thereby increasing the dissolution of COCs
from the NAPL into groundwater. The more water
soluble, lower-molecular-weight (LMW), NAPL
constituents are then released and chemically
oxidized at a proportionally higher rate, thus
leading to a "hardening" or "chemical weathering" of
the residual NAPL mass. The selective removal of
the more labile constituents causes a net increase
in the viscosity of the NAPL, yielding a more stable
NAPL source that is less susceptible to dissolution
processes. In addition, the oxidation from the permanganate portion of the RemOx EC formulation
precipitates manganese dioxide (MnO2) and
results in the formation of a "chemical shell" or
encapsulation which further isolates the "weathered"
NAPLs. As such, the flux of COCs into the dissolved
phase is decreased. By reducing the volume of NAPL
in the groundwater, the toxicity of the NAPL to the microbes is reduced,
allowing the microbial populations to flourish and
the natural attenuation processes to more
effectively manage COC plumes.
The merits of any type of treatment technology can
be assessed in terms of effectiveness, ease of use,
and cost. The use of RemOx EC for in situ
biogeochemical stabilization is fast, effective and
results in NAPL management. RemOx EC
is readily available from Carus Corporation who will
instruct and supply information for safe handling.
RemOx EC can be mixed and injected at the
site. The equipment needed is moderately
inexpensive compared to other technologies.
Figure 1: Chemical Shell |
Applying RemOx® EC for In Situ
Biogeochemical Stabilization |
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The application of RemOx EC Stabilization
Reagent will be very similar in terms of design,
equipment requirements, and costs to the application
of ISCO with permanganate. RemOx EC is a
liquid with some solids suspended in solution. RemOx EC Stabilization Reagent is injected into the
aquifer via a variety of application
techniques. With RemOx EC the goal is not to chemically oxidize all of the
carbon from the environment resulting in the actual volume of
reagents required being less than a typical ISCO
injection. A great side benefit of RemOx EC is the ease of application
and reduction in the delivery costs, making this
technology even more economically attractive. |
Economic Evaluation
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To get the
greatest impact, it is important to determine the
scope and limits of the RemOx EC application.
Time, resources, plume size, climate,
concentration of contaminants, and geology are
some of the variables that will factor into the cost
of a site. A specially-designed calculator has
been created and can be utilized by you and your Carus
Representative to determine the economic viability
of each given site. |
This technology is being jointly developed with
Adventus.
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