This presentation will provide information on anaerobic biodegradation of PHCs. The effectiveness of this cost-effective technology and case studies will also be discussed.
Event Overview
It was once thought that aromatic hydrocarbons do not biodegrade under anaerobic conditions. However, the importance of naturally occurring anaerobic oxidation processes in the biodegradation of petroleum hydrocarbons (PHCs) is now firmly established and is considered to be the dominant driving force in natural attenuation of PHCs in the subsurface. This process occurs through the oxidation of the PHC with the reduction of inorganic terminal electron acceptor compounds such as nitrate, sulfate and iron (Van Stempvoort et al., 2007).
Sulfate reduction and methanogenesis appear to be the dominant natural degradation processes at most sites (Wiedemeier et al., 1999). A BP – EPA study on the median consumptions of electron acceptors at 74 sites concluded that most hydrocarbon plumes are anaerobic and depleted of sulfate. | |  |
Based on a solid body of published scientific evidence, adding electron acceptors such as EAS™ (U.S. Patent # 7,138,060) to groundwater will aid in increased degradation. EAS™ addition will stimulate biodegradation by providing a soluble, readily available electron acceptor. In the presence of elevated SO4-2, anaerobic groundwater bacteria use the PHCs for carbon and energy while mineralizing the hydrocarbons to CO2 and H2O. In addition, SO4-2 reduction consumes protons increasing the pH and enhancing methanogenesis.
References
Van Stempvoort, D.R., Armstrong, J., Mayer, B., 2007. Microbial reduction of sulfate injected to gas condensate plumes in cold groundwater. Journal of Contaminant Hydrology 92 (2007) 184–207.
Wiedemeier, T, Rifai, H, Newell, C and Wilson, J 1999, Natural Attenuation of Fuels and Chlorinated Solvents in the Subsurface, John Wiley & Sons, Inc. New York.