The Boom in In Situ Bioremediation

Brubaker, Gaylen R.; ,

The Boom in In Situ Bioremediation

by Gaylen R. Brubaker, Principal; Remediation Technologies, Inc., Chapel Hill, NC,

Serial Information: Civil Engineering—ASCE, 1995, Vol. 65, Issue 10, Pg. 38-41

Document Type: Feature article

Abstract:

In situ bioremediation was first applied in 1972 when a subsurface release of high-octane gasoline threatened the water supply of a small town in Pennsylvania. Soluble inorganic nutrients and aeration accelerated the biodegradation of hydrocarbons. Since then, research and applications have increased. The method is increasingly being used now, principally to decontaminate or to protect ground water. In recent years, there have been improvements in oxygen delivery, new hydrogeological strategies, and the industry has improved its ability to forecast performance. Remediation processes involve the reduction of molecular oxygen to water while an organic compound is oxidized to create energy, cell mass and carbon dioxide. Oxygen transport has been the limiting factor. Recently scientists have explored the use of hydrogen peroxide to deliver greater quantities of oxygen. Air sparging, or injecting oxygen, is also described. Solid-phase oxygen release systems are a newer method in which a relatively insoluble oxygen in a matrix gradually releases oxygen when exposed to water. Bioavailability, or the rate of constituent dissolution, is also discussed. This is a problem with dense aqueous phase liquids, and the best strategy may be to prevent migration of dissolved constituents beyond the source zone. Intrinsic biodegradation or the natural unassisted biodegradation of contaminants is also being studied. The use of zero valent iron to reduce contaminants, especially chlorinated solvents, and nitrate reducing bacteria are also discussed. In the future, we are likely to see in situ bioremediation of chlorinated solvents by anaerobic methods, although this will be limited because of cost and complexity.

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