Bioremediation Treatability Studies for Soils Containing Herbicides, Chemicals, and Petroleum Products

Leaking underground storage tanks are widespread throughout the United States. It is estimated that there are 1.4 million underground gasoline storage tanks in the United States, with as many as 75,000 to 100,000 that may be leaking. In Indiana alone, more than 3,500 of the 15,000 registered underground storage tank facilities have reported leaks. Conventional remediation methods often involve pump-and-treat schemes for contaminated water, and excavation and burial of contaminated soil in hazardous waste landfills. These methods increase the risk of exposure to pollutants for workers and local residents. Furthermore, these methods merely involve the transfer of pollutants from one environmental compartment to another, and are rather costly. Bioremediation is another method available for the restoration of contaminated sites. Advantages of bioremediation include competitive cost, pollutant destruction, and minimal environmental disturbance. By biodegrading organic pollutants on site, exposure to pollutants is minimized and costs are reduced. Bioremediation can potentially be an effective, low-cost, and terminal solution for remediation of sites contaminated with organic pollutants. The goal of bioremediation is to accelerate the biodegradation rates of naturally occurring microorganisms that utilize organic pollutants as a food source. The overall objective of this study was to determine whether bioremediation is a feasible treatment option for contaminated INDOT soils. All INDOT solids tested had three things in common. First, a thriving heterotrophic microbial population existed. Second, bacteria capable of degrading benzoate (a toluene surrogate) were present in all soils. Finally, toluene evidence that physical, rather than microbial, parameters control biological processes in soil. Based on these results as a whole, we conclude that in-situ bioremediation of petroleum hydrocarbons is a treatment option which should have increased utilization