Use of Oil-Eating Bacteria on Spills Is Successful but Short of a Cure-All

The use of oil-eating microbes has become an accepted and safe method of cleaning up oil spills, but not a panacea, researchers say.

Scientists who used fertilizers to speed the biological degradation of Alaska’s massive oil spill are pleased with the way bioremediation worked there.

They are skeptical at best, however, about claims of overnight success on a spill in the Gulf of Mexico and the performance of laboratory-grown, rather than natural, bacteria.

“It’s not a magic cure,” said James Clark, an aquatic biologist at the U.S. Environmental Protection Agency lab in this Panhandle barrier island community. “There are times when it won’t be very effective.”

Clark represents EPA in a joint program with Exxon and the Alaska Department of Environmental Conservation. It began last year after the tanker Exxon Valdez spilled about 11 million gallons of crude oil in Alaskan waters.

In 1989, fertilizers were applied to 74 miles of Alaskan shoreline to make oil-eating microbes already there grow and devour the crude faster.

It was the first time bioremediation had been used on a U.S. spill and the largest such project ever undertaken. Previous uses have included treatment of sewage and hazardous wastes.

“The monitoring and research show that it had no adverse ecological effects. We saw no algae blooms, no toxicity to the fish,” Clark said. “The basic understanding of increasing the bacteria by adding nutrients is going to be an accepted technique.”

Bioremediation, however, represented only a fraction of the cleanup effort in Alaska, where 1,245 miles of coastline had been coated with oil.

Studies show that nitrogen and phosphorous fertilizer, some of it just like that used on lawns and gardens, increased the degradation rate by 30% to 50%, Clark said.

That still means that it could take from a few weeks to four years, depending upon the amount of oil present, to complete the decomposition, he said.

The next step in the laboratory and at spill sites is to see how bioremediation strategies may vary. “We may have to use different kinds of fertilizers or do something different in the Gulf of Mexico than Alaska,” Clark said.

Texas officials in July claimed a major success for bioremediation. They applied 100 pounds of laboratory-produced microbes to one acre of an oil slick in the gulf from the June 8 explosion of the supertanker Mega Borg, 57 miles off Galveston.

It was the first time bioremediation had been used in open water. Texas Land Commissioner Garry Mauro said surface oil was reduced by 30% in some samples a day after the application, while no such reduction was found in an untreated portion of the slick.

But Clark said he is skeptical.

“Our studies have shown oil degradation occurs in the course of days and weeks, not hours,” he said. “It’s very hard for us to understand how it would degrade overnight.”

Clark called the controversy “a touchy issue” for EPA, which officially says more research is needed about bioremediation at sea.

A blunter assessment came from Jim Mueller, a microbiologist for Southern BioProducts, an Atlanta-based bioremediation company EPA has hired to help with research.

“I don’t think it worked. I think they sank the oil,” Mueller said. “Studies we have done with very high concentrations of organism, optimum nutrient, optimum temperature, (show) it still takes days and weeks.”

Experiments are under way with two brands of commercially grown microbes, but preliminary evidence shows they are no better than natural bacteria, Clark and Mueller said.

On the other hand, research on new ways to apply fertilizers has been promising.

In Alaska, a special oil-attracting fertilizer known as Inipol EAP 22, made only by the French company Elfe Aquitaine, was sprayed in liquid form. Garden-variety water-soluble fertilizer was applied in granular form with lawn spreaders.

While Inipol has been more effective in cleaning up visible oil, water-soluble fertilizers are better at seeping below the surface.

Mueller is experimenting with simply hosing down oil-tainted shores with water-soluble fertilizer.

“Potentially what we can do is get on a boat with a fire hose and just blast the beaches with soluble nutrient, let the rocks bathe in it during low tide,” he said.

That would make application simpler and cheaper. Bioremediation already costs less than most other cleanup methods.

Bioremediation has cost about 25% as much as incineration for cleaning up hazardous waste sites, Mueller said. Clark figured the price difference would be at least that much for oil cleanups in which the alternatives include physically wiping off rocks or dumping them in landfills.