Using Biodegradation as a Remediation Tool

Article excerpt

Throughout the world, environmental engineers and consultants apply natural biodegradation (i.e., natural attenuation or intrinsic biodegradation) as an accepted form of remediation for many contaminated-soil sites. In the United States, there are, however, several challenges in presenting this type of remediation to the U.S. Environmental Protection Agency (U.S. EPA) and other regulatory agencies. For example, how does one determine what favorable conditions are required for biodegradation? Which type of monitoring indicates that natural attenuation is actually taking place? U.S. EPA and the Air Force Center of Excellence have assisted by publishing documents that may soon become industry standards for demonstrating natural attenuation.

After completion of site characterization and contaminant identification the next step is to assess the presence of natural bacteria by testing a soil sample. A heterotrophic-plate-count (SM9215B) analysis indicates the number of bacteria able to grow, and a most-probable-number (SM9223B) coliform analysis assesses the presence of aerobes such as nitrate and sulfate reducers and methanogens. Also, the hydrocarbon-degrading-bacterial-plate-count (ASM) analysis can enumerate populations of bacteria that have the ability to degrade gasoline, diesel, jet fuel, and other hydrocarbons. …