Sulfate Enhanced Bioremediation
Electron Acceptor Solution (EAS™)
Paradigm Shift in the Remediation of Petroleum Hydrocarbons -Sulfate Enhanced Technology, U.S. Patent No. 7,138,060
Soil and groundwater clean-up is critical to sustainable business practices across many industries. Since 2002, EOS Remediation has provided site owners and engineers with innovative, environmentally responsible solutions to remediation challenges through its R&D, products and technologies.
In 2009, EOS Remediation commercialized EAS™, a sulfate-enhanced technology for in situ remediation of contaminated groundwater. The conventional wisdom for remediation of aquifers contaminated with petroleum hydrocarbons (PHCs) is to add oxygen. EAS™ stimulates biodegradation by providing a soluble, readily available electron acceptor. In the presence of elevated sulfate, anaerobic groundwater bacteria use the PHCs for carbon and energy while mineralizing the hydrocarbons to carbon dioxide and water. EAS™ is a “Green Technology” that accelerates site cleanup. EAS™ enhances natural conditions and reduces carbon foot print when compared to conventional remediation – a socially responsible approach to remediation.
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. Sulfate reduction and methanogenesis appear to be the dominant natural degradation processes at most sites (Wiedemeier et al., 1999). A recent British Petroleum/EPA study has concluded that most hydrocarbon plumes are anaerobic and depleted of sulfate. Other studies have drawn comparable conclusions. This process occurs when terminal electron acceptor compounds such as nitrate, sulfate and iron react to reduce PHC concentrations. 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).
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. The following equation illustrates this concept using toluene as the PHC and “B” representing bacterial metabolism.
The reaction results in complete degradation of the BTEX components.
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
†Exclusive license agreement under U.S. Patent No. 7,138,060.