On the Removal of Chlorinated Solvents from
Groundwater Aquifers
Just when we thought we had it all down pat…
Chlorinated solvents are the single largest environmental threat to
groundwater in the world. Chlorinated solvents have properties that make
them useful for degreasing fats, oils, waxes, and resins. Historically they
have been used widely in dry cleaning and industrial degreasing operations
and manufactured in large quantities. Some chlorinated solvents are
dichloromethane, tetrachloroethene, trichloroethane, and tricholoroethene.
The U.S. production of these compounds in 1980 was 255,000, 347,000,
314,000, and 121,000 metric tons, respectively.
Chlorinated solvents are harmful to human and ecological health. They can
cause or are suspected of causing cancer, and are toxic or harmful to aquatic
organisms.
Spills and leaks of chlorinated solvents have caused widespread subsurface
contamination in the environment. Because the density of these substances
is greater than water, they sink in groundwater systems (aquifers) in
complex dispersal and plume patterns, resulting in long-term sources in the
subsurface, and difficult cleanup. Commonly these contaminants are present
in the subsurface in the form of bulk chemical product also known as dense
non-aqueous phase liquids (DNAPL), as dissolved contaminants in ground
water, in contact (adsorption) to aquifer sediments, and as vapors in the
unsaturated zone.
The traditional method used to clean up chlorinated solvents in ground water
has been through pump and treat that is highly ineffective. For soils cleanup,
excavation and disposal at a special landfill has been used which is very
expensive and shifts the problem from one site to another. As these solvents
are volatile, a technology known as “soil-vapor extraction” has been used to
clean up soils that are permeable like various rock formations; however, this
technology does not work well in tight soils like various combinations of clay
and silt. Attenuation through natural anaerobic microbial processes has been
problematic insofar as it is very slow and the daughter products created
through the process, dichloroethene and Vinyl Chloride, are more toxic than
the original contaminates.
However, there is a new kid on the block…….
SMEcl Technology
Professor Alan Harker, PhD in microbiology from Brigham Young University,
has created a variant of a naturally occurring aerobic bacterium by inserting
an additional enzyme in it. It completely degrades chlorinated solvents and
leaves nothing but CO2, salt and water behind.
To utilize Dr. Harker’s special bug, we use a delivery system known as
Subsurface Metabolic Enhancement (SME), created by Mark Ellis of Lehi,
Utah, US patent #6,464,005. A grid work of pipes is developed into the
contaminated soil(s) and water. Air is then injected at a very low pressure so
as to saturate the substrate. What this does is turn the environment from
anaerobic to aerobic. Aerobic bacterial action is 15 to 20 times faster than
anaerobic. The bacteria and nutrients are also delivered through the grid
work. To keep the bugs healthy, we clean up after them by extracting their
CO2 waste product.
It is completely green, safe and fast. When coupled with the SME delivery
system created and patented by Mark Ellis, we achieve an optimal solution
to the most widespread groundwater contamination problem in the world.
Ami Adini & Associates, Inc., is licensed to use SMEcl.
For a brief overview of SME®, click here <hotlink>. For detailed
information on the science and application of SME® and the bacterium,
Ralstonia Eutropha variant, click here <hot link>. For case study data, click
here <hot link>.
For further information on the application of SME or SMEcl please contact
Paul Zumberge.
paul@amiadini.com
714-408-0418