Biodegradation and Bioremediation of Petroleum Pollutants in Soil

Abstract

Petroleum and its derived fuels, as a result of their widespread worldwide use, are probably the most ubiquitous organic pollutants found in soil. Each year, approximately 40,000 barrels or equivalently 1,680,000 gallons of crude oil are spilled on land due to pipeline failures (Salani-tro 2001). There are more than 200,000 underground storage tanks in the US alone that have leaked gasoline and other fuels into vadose zone soils (Bedient et al. 1994). A variety of physical and chemical treatment technologies such as incineration, thermal desorption, soil washing, and solvent extraction have been developed and tested for removing petroleum hydrocarbons from soils (Stegmann et al. 2001). Despite the fact that these technologies are successful in cleaning contaminated soils, they not only often destroy the soil structure or render the soil biologically impoverished, sometimes even completely sterile, but also are usually cost-prohibitive. By contrast, biological soil treatment technologies such as land farming, composting or biopile treatment, slurry bioremediation, and bioventing are not only cost-effective, but generally reduce hydrocarbon pollutant levels sufficiently to bring about a significant improvement in soil quality as indicated by marked reductions in ecotoxicity. As a result, bioremediation is the most commonly used treatment technology for petroleum polluted soils (Alexander 1994; Baker and Herson 1994; Cookson 1995).