A worker samples polluted mud in a test pit. Researchers are trying to break down contaminants in the mud using electrical charges. A German company developed the technology, which U.S. officials hope will be cheaper than dredging polluted sediments.
Photo courtesy of MPR.
One of the biggest challenges facing Great Lakes water quality comes from polluted harbors. Scores of underwater sites have been identified, but cleanup has been painfully slow. Now, some people are taking a new approach – they’re using an electrical charge to clean up pollutants. It’s the first test in this country of the system. Supporters say it’s cheaper and faster than conventional methods. The Great Lakes Radio Consortium’s Bob Kelleher reports:
One of the biggest challenges facing Great Lakes water quality comes from
polluted harbors. Scores of underwater sites have been identified, but
cleanup has been painfully slow. Now, some people are taking a new
approach – they’re using an electrical charge to clean up pollutants. It’s
the first test in this country of the system. Supporters say it’s cheaper
and faster than conventional methods. The Great Lakes Radio Consortium’s
Bob Kelleher reports:
Stryker Bay is a lovely little cove alongside the St. Louis River, near Lake
Superior, in Duluth, Minnesota. It’s a gentle water with ducks in the
summer; and a shady hiking path along the shore.
Tim Leland lives along the shore. From his home, he sees waterfowl, and
“Stryker Bay is a shallow bay. It’s six foot at the most of water.
But there’s a silt that’s underneath it, and all this tar and stuff that’s
coming up. Summertime there we do have a lot of oil that makes the surface
The bottom of Stryker Bay is a biological time bomb. Under the sand, are
pools of oily stuff – that experts call polynuclear aromatic-hydrocarbons,
or PAH’s. For nearly a century, Stryker Bay was an industrial sewer. PAH’s
were first identified under the bay in the 1970’s. That tar like stuff is
still there. There’s not enough money and little agreement how to get rid
But what if you could make pollution go away by throwing a switch? That’s
essentially what a German based company promises. And U.S. officials are
listening. The first underwater test in the United States of
Electrochemical-GeoOxidation treatment is underway in Duluth. And early
results show promise. It’s a simple concept, according to Ken Whittle with
Electro Petroleum Inc., who describes the process underway behind him in a
pair of water-filled pits.
“It’s a pretty simple kind of thing. If you want to look at it;
if you have a battery charger at home, you plug the battery charger in, you
take the two leads and you connect them to the terminals on a battery. Well,
that’s pretty analogous to what’s going on here.”
Each pit is filled with polluted mud and covered with water. Metal pipes
are sunken into the muck. In one pit, a carefully controlled electrical
charge pushes electrons through the sediment between the pipes. It’s
supposed to break the electron bonds of dangerous molecules; like PAH’s.
What’s left is harmless – like carbon and water.
The test is financed by the Environmental Protection Agency and the U.S. Army
Corps of Engineers: the agency responsible for dredging shipping lanes.
Dealing with polluted sediment is a huge expense, according to Army Corps
researcher Tommy Myers.
“It’s a real big problem for us to dispose of that material. We
can’t put it back into the water. And, typically, we confine it in what we
call a confined disposal facility, and just store the material into
perpetuity and let it break down by natural processes, if it will.”
Officials would rather destroy pollutants than store them, but conventional
methods are expensive, smelly, and noisy. And they all require dredging,
and that’s expensive.
“In this particular technology, it wouldn’t necessarily require
dredging. There’s very little noise or gaseous emissions associated with
it. The main thing is it could be applied in situ; that means in the water,
without having to dredge.”
Proponents say Electrochemical-GeoOxidation is a bargain. Pollution
officials say conventional methods might cost as much as 200 dollars to
clean up a single cubic yard of sediment from Stryker Bay. But, according
to David Bowman with the Army Corps of Engineers in Detroit, electrical
cleanup might cost a quarter of that.
“Our goal with this project was to find a technology that would
work for around one hundred dollars per cubic yard. The vendor talked about
that they might be able to treat material for around forty five to fifty
dollars per cubic yard at Duluth Harbor.”
And the contractor claims the process works fast. A typical site can be
cleaned in just a few months. It’s also supposed to work on metals, like
mercury, which attach to the electrodes, which can then be disposed of in a
hazardous waste facility.
In the Duluth test, PAH’s have decreased by forty five percent in about a
month. That’s promising, although far from conclusive. The process
won’t get every molecule, but it’s intended to reduce contaminants below
Tests began in Duluth this summer, but results are several months away.
For the Great Lakes Radio Consortium, I’m Bob Kelleher.