New bio- remediation agent: A Bacterium
That Gobbles Up Poison
October 19, 2003
By JONATHAN MILLER
AIRFIELD, N.J. The Caldwell Trucking Superfund site, a few miles west of the
Willowbrook Mall, is a nine-acre repository of poison-laced sewage, hauled here and dumped
until the 1970's, when the threat of drinking-water contamination was recognized.
About 50 private wells and two public wells had to be shut down, and even more drinking
water was threatened as contamination spread toward the Passaic River. The contamination
has now mostly been contained, but the latest cleanup stage has progressed fitfully at
And so three years ago, the federal Environmental Protection Agency started a daring
project to pump into the ground a mysterious and little- understood bacterium that munches
on the type of pollutants to be found here.
By all accounts, the use of the half-micron-long bacterium with the official name
Dehalococcoides ethenogenes has been a success. Technically, the bacterium a few
thousand could fit on the head of a pin ingests the toxic chemicals the way that
people breathe oxygen.
"It looks like the process is really working," said Tom Porucznik, remedial
project manager for the E.P.A. The agency will be looking at more results throughout the
fall, and will likely decide sometime in the spring whether to continue with the
The bacterium was discovered in 1997 by a team of scientists at Cornell University. They
found that it had a strange natural affinity for devouring dangerous industrial chemicals
like the one found at Caldwell Trucking trichlorethylene, or TCE, which was often
used as a heavy cleaner and is suspected of being a carcinogen. The bacteria have an
unusual cell wall, and are tiny even by bacterial standards. "They're really weird
organisms," said Dr. Stephen H. Zinder, the chairman of the microbiology department
at Cornell University.
Using the "bugs" as both he and others refer to D. ethenogenes is
a vast improvement over the pump-and-treat method, a tactic used at many polluted sites
that essentially pumps water to the surface in the hope of removing contamination.
"The bugs flow where the contamination is, because they're following the water,"
said Peter Herzberg, a lawyer for eight companies responsible for the cleanup at the
Caldwell site. "And you're getting to places where you couldn't get to mechanically
with a pump-and-treat system."
Once they get where they are going, the bugs find the TCE or other poisons and begin
devouring the chlorines from the molecules, leaving as a byproduct a harmless substance
called ethene. The procedure, called bioremediation, has been used in pilot programs in
California, Delaware, Texas and elsewhere to battle potential groundwater contaminants.
Many sites lie near Air Force bases, where a mixture of jet fuel and TCE often seeped into
the ground. Here, scientists and government officials have watched with surprise as the
bacterium has significantly reduced the levels of TCE, in some places by 90 to 95 percent.
To those who may wonder about replacing poisons with bacteria in groundwater,
officials and scientists say that thus far they see no ill effects. David W. Major, a
scientist for GeoSyntec, a company that produces a widely used strain of the bacteria used
at the site, said that once the feeding of D. ethenogenes stops, the organism simply dies,
with little impact on the environment. Still, Dr. Zinder of Cornell, who along with James
M. Gossett discovered the organism, said that unintended consequences were always a
"I'd say, you never know for sure, which makes people nervous," he said,
"but I think as technologies go, I wouldn't consider these pathogens. There's just no
In fact, over the past decade, bio- remediation has been used a number of times.
Fertilizer has been used to attack oil spills. In phytoremediation, plants are used to
clean up toxic metals.
On a clear, bright day, a little chilly by early October standards, a single propeller
plane passes overhead on its way to Essex County Airport,
and it seems that little is detectably wrong at this nine-acre spot in northern New
Jersey. But the whine of a generator and the site of seven milky-white 55-gallon drums
rising from the ground quickly dispel that notion.
These drums are a kind of feed bag for the bacteria. Each day, Joe Huffman, a geologist,
sends a concoction of nutrients, including lactate, into the ground. "It's like a
buffet for the homeless," he said.
Chris Young, a project manager for the site, is stomping over what was once the
"central lagoon," where the heaviest contamination from the
septic sludge remains. Now, millions of poison-munching bacteria are burrowing into the
soil's convoluted pathways where only a bacterium
"In those tortuous paths," Mr. Young said, "we're just trying to get these
nutrients down, get them feeding the organism in place, and get these
Obviously, the more they increase, the more they eat.
Copyright 2003 The New York Times Company