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EHC® Granules
Client Testimonial: Oregon Site
"Our client needed an in situ remedy that could selectively
remove TCE from groundwater in the presence of hydrocarbon
DNAPL. Bench trials demonstrated that EHC outperformed other
technologies (emulsified oil and lactate-based). The subsequent
pilot tests included creating a bioaugmented EHC permeable
reactive barrier at depths ranging from 50 to 130 feet below
ground, using traditional direct-push equipment. Five months
following injection, the concentrations of TCE were reduced
from approximately 100,000 ppb to below method reporting
limits with sustained, negative redox conditions, and no
accumulation of catabolites. Because of the relative cost,
ease of implementation, and safety of the product, we expect
to recommend future installations of EHC at this and many
other sites."
-James Peale, Senior Hydrogeologist Maul Foster & Alongi,
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EHC® Environmental Remediation
Products
EHC® technology describes a family of remediation products
used for the in situ treatment of groundwater and
saturated soil impacted by heavy metals and persistent organic
compounds such as chlorinated solvents, pesticides and energetics.
The technology is a modification of our DARAMEND® technology
which has been used since 1992 to treat over 3,600,000 tons
of similarly effected soil and sediment. Both EHC® and
DARAMEND® are the subjects of numerous patents owned
by Adventus Intellectual Properties, Inc. (Adventus).
EHC® is a controlled-release, integrated carbon and
zero valent iron (ZVI) source that yields redox potential
(Eh) in the -500 to -650 mV range. This Eh is significantly
lower than that achieved when using either organic materials
(lactate, molasses, and sugars) or reduced metal alone. Eh
potentials in this range facilitate the timely and effective
removal of normally recalcitrant chlorinated organics (e.g.,
CT, PCE) and other persistent compounds (e.g., perchlorate)
without the formation of potentially problematic intermediates,
such as DCE/VC from the anaerobic degradation of PCE/TCE
or CF/DCM from the anaerobic degradation of CT.
Watch this video to see the simulated effects of EHC injected
as a PRB; plume cut-off of Carbon Tetrachloride. Site: Grain
Silo Facility, Kansas USA.
EHC® Formulations
EHC® comes in a variety of formulations to meet the
requirements unique to each site. Standard EHC® is a
solid material available in pellets, granules or powders.
EHC® can be applied via a variety of construction methods
providing in situ source area treatment or plume
management (Permeable Reactive Barriers).
- EHC-M® is specially
prepared for treatment of heavy metals.
- EHC-O® contains
a slow-release oxygen source for rapid removal of petroleum
hydrocarbons and other compounds that are amenable to aerobic
biodegradation processes.
- EHC-A® is
a liquid formulation provided as a suspendable solid or
an aqueous solution for easy application to existing wells
or other networks.
The organic component of EHC (fibrous organic material)
is nutrient-rich, hydrophilic, and has high surface area;
thus, it is an ideal support for growth of bacteria in the
groundwater environment. As they grow on EHC particle surfaces,
indigenous heterotrophic bacteria consume dissolved oxygen,
thereby reducing the redox potential in groundwater. In addition,
as the bacteria grow on the organic particles, they ferment
carbon and release a variety of volatile fatty acids (VFAs,
for example acetic, propionic, butyric), which diffuse from
the site of fermentation into the groundwater plume and serve
as electron donors for other bacteria, including dehalogenators
and halorespiring species. Finally, the soluble ferrous sulfate
particles provide substantial reactive surface area that
stimulates direct chemical dechlorination and an additional
drop in the redox potential of the groundwater via chemical
oxygen scavenging. These physical, chemical, and biological
processes combine to create an extremely reduced environment
that stimulates chemical and microbiological dechlorination
of otherwise persistent compounds
1. Comparison of Commercially Available In Situ Groundwater
Treatment Products
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