Minnesota Public Radio
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 in Duluth 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.
Duluth's Stryker Bay is a lovely
little cove alongside the St. Louis River. It's a gentle
water with ducks in the summer and a shady hiking path
along the shore.
Tim Leland lives along Stryker Bay.
From his home, he sees waterfowl, and fouled water.
"Stryker Bay is a shallow bay. It's
six foot, at the most. But there's a silt that's underneath
it, and all this tar and stuff that's coming up. (In)
summertime we do have a lot of oil that comes up to the
surface," says Leland.
The bottom of Stryker Bay is a biological
Under the sand are pools of oily stuff
experts call polynuclear aromatic-hydrocarbons, or PAHs.
For nearly a century, Stryker Bay was an industrial sewer.
PAHs were first identified under the bay in the 1970s.
They're still there. There's not enough money, and little
agreement, on how to get rid of them.
But what if you could make pollution,
like PAHs, 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 geo-oxidation treatment is underway
The early results show promise. It's
a simple concept, according to Ken Whittle of Electro
Petroleum Inc., who describes the process going on in
a pair of water-filled pits behind him.
"It's a pretty simple kind of thing,"
Whittle says. "If you have a battery charger at home,
you plug the battery charger in, you take the two leads
so you connect them to the terminals on the battery. That's
pretty analagous to what's going on here."
Each pit is filled with polluted mud
and covered with several feet of water. Metal pipes are
sunk 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 PAHs. 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," Myers says. "We confine it in what we call a confined
disposal facility, and just store the material into perpetuity
and let it break down into 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.
"In this particular technology, it
wouldn't necessarily require dredging," Myers says. "There's
very little noise or gaseous emissions associated with
it. The main thing is, it could be applied ... in the
water, without having to dredge."
Proponents say electrochemical geo-oxidation
is a bargain. Pollution officials say conventional methods
might cost $200 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 one-fourth as much.
"Our goal with this project was to
find a technology that would work for around $100 a cubic
yard," says Bowman. "The vendor talked about that they
might be able to treat material for around $45 to $50
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. In the Duluth test, PAHs have decreased by 45
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 dangerous
It's also supposed to work on metals,
like mercury, which can be drawn to the electrodes. Even
radioactive isotopes can be collected, according to the
The test begun in Duluth this summer
is winding down now that cold weather has arrived. Final
results are several months away. Meanwhile, the company
has set up a second demonstration, under the waters of
Puget Sound, off the coast of Washington state.