Nancy Van Prooyen looks at some of the new technology that is being used to clean up the BP oil spill.
|A worker cleans up oily waste on Elmer’s Island, just west of Grand Isle, La., in May. Photo credit: U.S. Coast Guard Petty Officer 3rd Class Patrick Kelley.
On April 20, an explosion in the Gulf of Mexico, off the coast of Louisiana, rocked the Deepwater Horizon oil rig. Colossal environmental damage caused by the oil spill has continued since this incident dominated headlines around the world. British Petroleum, the oil giant that operated the rig, has come under relentless public pressure and mounting criticism for its ineffectual handling of this ecological tragedy. Even now, hundreds of thousands of barrels of oil are spilling into the ocean each day and are carried inward by currents to delicate marshes and wetlands. The coastal wetlands already suffer from overpopulation, pollution and lingering effects from Hurricane Katrina. It will take years for us to realize the true impact of the spill on the surrounding ecosystems.
Unfortunately, the United States coastline is no stranger to catastrophic oil spills. Although the BP spill is now the largest ever, the previous holder of this dubious distinction was the Exxon-Valdez spill of 1989. Currently, BP is implementing crude and outdated methods inherited from past spills for the offshore cleanup.
There are three conventional methods that are used widely to collect or clean up oil from water:
1. Water-oil separation: BP has employed hundreds of vessels, including some of the largest skimmers in the world, to skim the surface of the water and manually collect floating oil. Although this method works well in calm, isolated water, strong ocean currents largely render it ineffective. BP also uses centrifuges to separate oil from the gathered seawater. However, these centrifuges have varying efficiency in removing the oil, making this a rather costly procedure in terms of time, effort and money.
2. Controlled burns: In a more extreme attempt to remove the oil, BP is burning large areas of oil on the sea surface. This releases greenhouse gases such as sulfur dioxide, nitrous oxides and methane into the air. The thick black clouds are then carried into the lungs of workers and residents in the coastal communities. People with asthma or serious heart problems are particularly susceptible to the toxic burn-off. Tragically, large numbers of marine wildlife that live near the water surface often are corralled into the areas demarcated for combustion, and are, quite literally, burned alive.
3. Chemical dispersants: The third main method BP is using to clean up oil involves sprinkling large amounts of chemical dispersants by boat, aircraft and workers on the shore. Dispersants cause the oil to break up into smaller droplets, which become miscible in water. However, these dispersants may result in more ecological harm than good. The chemicals contain nonbiodegradable toxins that can kill fish and migrate great distances. Dispersants also are blamed for the massive oil plumes several hundreds of feet underwater, harmful to all aquatic life, especially fish larvae and filter feeders. Moreover, because of the large volume of oil that has been spilled, the amount of dispersant required and the amount of oil dispersed simply suppresses the problem, rather than solving it.
|Health, safety and environment workers contracted by BP clean up oil on a beach in Port Fourchon, La. Photo credit: U.S. Coast Guard Petty Officer 3rd Class Patrick Kelley.
The most high-profile and promising new technology available to clean up the oil spill is bioremediation, which potentially could remove the oil in a harmless manner, from even the most intractable and messy environments, where it has sunk into beaches and mangrove swamps, and even in underwater oil plumes. Some naturally occurring microbes that process crude oil are known to exist in the ocean. However, the amount of oil gushing into the ocean as a result of the BP oil spill is far more than the natural habitat can handle. Thus, many companies have turned to bioremediation, which is any process that utilizes bacteria, fungi, green plants or enzymes to naturally remove contaminants.
Potential bioremediation applications for an oil spill mainly fall into two categories: biostimulation and biofermentation. Biostimulation involves modifying the environment to stimulate the indigenous bacteria capable of bioremediation. Many biotech companies are pursuing novel ways of boosting the natural flora to help remove the excess oil. One product accidently discovered by National Aeronautics and Space Administration scientists is called “Petroleum Remediation Product,” now distributed by the Pittsburgh-based Universal Remediation Inc. PRP is a powder that contains thousands of beeswax microspheres with hollow centers. The 0.25- to 0.65-μm spheres are impervious to water, but oil is absorbed in their centers as they float on the water surface. The capsules can absorb up to 20 times their weight in oil. The beeswax attracts naturally occurring microorganisms, which eat the wax and oil, safely biodegrading the petroleum and PRP. After the PRP and oil are consumed, the expanded microbe population dies off. Thus, the oil is removed, the bacterial bloom is controlled, and the natural environment is restored.
PRP products also can contain Pseudomonas bacteria that eat hydrocarbons found in crude oil. This combination of introducing oil-eating bacteria and providing a food source for native bacteria effectively can speed the rate of oil decomposition. PRP is extremely useful in ecologically-sensitive regions, such as wetlands, marshes, nesting areas and grasslands, where conventional methods are impossible.
Biofermentation uses genetically engineered microbes that metabolize oil at a rapid rate, which can dramatically speed up the rate of oil cleanup. However, often when these designer bacteria are introduced into diverse and hostile environments, they are outcompeted by native bacteria. Evolugate, a bioremediation company in Gainesville, Fla., is working to increase the oil-consuming efficiency of naturally occurring bacteria through adaptive pressure. Scientists at Evolugate isolate natural oil-consuming bacteria found in the Gulf and place selective pressure on the microbes to improve their oil-eating abilities. Each time the bacteria divide, their genomes mutate. Providing oil as their only food source creates a strong selective pressure that enhances bacterial evolution. And, because the designer bacteria are derived from native flora, they have a better chance of surviving when reintroduced into the Gulf.
The superbacteria are dispersed in large quantities, using biofermentors to build up dense growths for immediate dispersal into the sea water. This way, the targeted delivery of relatively high concentrations of oil-eating bacteria near the biggest oil spills prevents them from being outcompeted for oxygen and nutrients by the local flora. These large biofermentors also can be mounted on boats for a ready supply of healthy oil-digesting bacteria.
As the monetary value of the oil collected by centrifugation is miniscule in comparison to the money being spent containing the spill, the main focus of the cleanup effort should now be to rapidly and efficiently scrub the oil from the sea surface, the underground oil plumes and the coastlines where the oil has washed ashore. To effectively clean up a disaster of this magnitude, we need to use a multitude of techniques, and green remedies that use bioremediation should be part of the solution.
Nancy Van Prooyen (firstname.lastname@example.org) is a postdoctoral fellow at the National Cancer Institute.