BIOREMEDIATION TESTS SHOW PROMISE

First bioremediation tests in major spills yield encouraging results and no harm to environment. Exxon to continue Prince William Sound program. Mega Borg spill test, first in open seas, supported by Port Aransas, Tex., laboratory tests.

Tests of bioremediation's effectiveness in cleaning up spilled oil onshore and at sea apparently support laboratory test successes.

Here are some examples of what's happening:

Seven hr after the first open sea application of bioremediation, a mix of microbes and fertilizer significantly decreased oil concentrations in water samples collected after the June 8 Mega Borg tanker spill in the Gulf of Mexico.
Officials overseeing cleanup of Prince William Sound shorelines contaminated by the Mar. 24, 1989, Exxon Valdez tanker spill reported that naturally occurring microbes consumed oil three times faster when treated with liquid and granular fertilizers.
A controlled demonstration test last October at the University of Texas Marine Science Institute, Port Aransas, Tex., showed microbes reduced oil concentration by 99.99% in a column of seawater.

"The results show we are close to having a tool that cleans up oil spills," said Texas General Land Office Commissioner Garry Mauro. He was commenting on preliminary findings of bioremediation tests related to the Mega Borg spill.

Bioremediation is unlike skimmer vessels, which under the best conditions typically recover about 20% of an oil spill, Mauro said.

The June 15 and 18 Mega Borg bioremediation tests were the first use of microbes to clean up spilled oil in open seas, said officials of the land office and Texas Water Commission, which cooperated in the experiments.

Texas officials said the uncontrolled June 15 test on a 40 acre oil slick coming from the Mega Borg showed microbes can be used effectively at sea on large spills and can be applied rapidly in large volumes.

In a controlled application June 18, researchers attempted to quantify reductions of oil on the surface and in the water column. Officials said the experiments confirmed, as did results of the Port Aransas test, that microbial agents are not harmful to marine life.

OPEN SEA TEST

In the first Mega Borg spill bioremediation test, researchers aboard a U.S. Coast Guard vessel applied 110 lb of a commercial microbial agent in a concentration of 1 trillion bacteria/g dry weight combined with nitrogen and phosphorous.

The microbial agent, Alpha Biosea Process (ABP) developed by Alpha Environmental, Austin, Tex., was mixed with fertilizer and seawater in a 55 gal drum and sprayed on the surface of the slick in a slurry of about 3 lb/acre. Treatment took about 30 min.

Although quantitative data weren't obtained, oil treated by the microbes changed from a continuous brown film and sheen to discrete areas of mottled brown and yellow material, the test report said.

Aerial reconnaissance 16 hr later revealed no sign of oil in the treatment area. However, researchers were uncertain whether that was due mainly to bioremediation, wind and wave action, or skimming.

In the later, controlled test, researchers deployed and marked a test and a control float around each of two oil water mousse streamers.

They collected pretreatment samples and spread 3.5 lb of microbes and 1.5 lb of inorganic nutrient as a dry powder across the surface of the test streamer.

Four times at about 2 hr intervals, researchers took samples of surface mousse, surface water, shallow subsurface water, and deep water.

Open sea conditions resulted in widely variable pretreatment samples, so researchers discounted statistical validity of the tests. But, they said, treatment area samples consistently showed lesser oil concentrations than comparative samples obtained from control areas.

"While not conclusive, the preliminary results confirm the capacity of the product used in the application for degrading oil and the absence of either toxic byproducts or damage to the nutrient balance of the natural marine environment," the report said.

EXXON RESULTS

In Alaska, successful stimulation of oil degrading microbes in tests beginning early in May has paved the way for Exxon Corp. to finish fertilizing about 400 relatively small sites previously targeted for bioremedial cleanup along Prince William Sound shorelines.

About 200 of those sites have been treated. Three treated sites were monitored for a 6 week period by the Coast Guard, Environmental Protection Agency, National Atmospheric & Oceanic Administration, Alaska Department of Environmental Conservation (ADEC), and Exxon.

"The results of this program also will serve as the basis for possible recommendations regarding the need and appropriate timing for a reapplication of fertilizers," said Bob Mastracchio, Exxon technical manager in Alaska.

A panel of scientists continued reviewing test results.

ADEC Commissioner Dennis Kelso said data showed bioremediation, if applied properly, could be used successfully to clean shorelines where oil concentrations were less than 5 parts per thousand. Where useful, beaches are to be treated every 30 days with fertilizer until there is no more oil for microbes to degrade, he said.

Officials also concluded that using measured doses of fertilizer on shorelines poses no threat to fish or wildlife.

"It works, it's helpful, and it doesn't harm the environment," said Exxon spokesman Joe Tucker.

Exxon has advocated bioremediation in selected cases to clean up oiled shores in the sound. Its spreading of fertilizer on 70 miles of shoreline was the first use of the technology in a major spill.

Tests at Exxon's Clinton, N.J., research laboratory showed that nutrients and oxygen penetrate to depths of as much as 2 ft in some high energy shorelines-deep enough to allow microbes to degrade subsurface oil.

PORT ARANSAS DEMONSTRATION

The Port Aransas demonstration suggested bioremediation can reduce the effect of marine oil spills.

For that test, crude oil was applied to the surface of seawater in two open concrete tanks at concentrations of 2 bbl/acre. One tank was the test vessel, the other control. To avoid confusing evaporation with effects of bioremediation, the oil was aerated for 24 hr prior to application.

Immediately after the oil was released into the test tank, it was inoculated with ABP at a concentration of 5.22 million bacteria/sq cm. Both tanks were aerated by multiple aquarium bubblers.

To demonstrate effects of the treatment on native marine life, oysters, shrimp, and mullet were introduced to both tanks and monitored for toxic effects. Shrimp are motile water column filter feeders, mullet grazers, and oysters sessile, bottom dwelling filter feeders.

The Lower Colorado River Authority (LCRA) throughout the test collected samples of water, oil, and sediment from both tanks. Samples involved surface phase (filter absorbed), water column phase, and sediment phase (particulate fallout).

LCRA collected samples at the outset and after various times during the test.

ARANSAS TEST RESULTS

After 6 hr, surface phase oil concentration in the test tank decreased 65% compared with a control concentration, water phase concentrations in both tanks were unchanged, and test sediment decreased by 96.4% vs. control sediment.

After 24 hr, surface concentration of oil in the test tank had decreased by 80% compared with 48% control concentration, and water column phase oil concentration had plunged by 99.99% compared with 56.8% control concentration.

Because new bottles were used 6 hr into the experiment to collect sediment samples, that resulted in an 18 hr sample for the sediment phase. This sampling procedure found decreases of 91.9% in test sediments and 82.1% in control sediments.

Testing personnel reported early changes in appearance of the test tank, where oil turned into a mousse-like substance on which shrimp and mullet fed.

The same feeding behavior was seen in 10 gal test aquariums.

Also, residues collected by finger testing of both tanks behaved differently. While residue from the control tank couldn't be removed easily by rinsing with water, residue from the test tank appeared to be easily water soluble.