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SIGNIFICANCE OF AN ANAEROBIC PROCESSES FOR THE INTRINSIC BIOREMEDIATION OF FUEL HYDROCARBONS
Citation:
Wiedemeier, T. H., R. N. Miller, J T. Wilson*, AND D H. Kampbell*. SIGNIFICANCE OF AN ANAEROBIC PROCESSES FOR THE INTRINSIC BIOREMEDIATION OF FUEL HYDROCARBONS. Petroleum Hydrocarbons & Organic Chemicals in Ground Water Conference, Houston, TX, 11/29-12/01/1995.
Description:
Intrinsic remediation is an innovative remedial approach that relies on natural attenuation to remediate contaminants dissolved in ground water. Mechanisms of natural attenuation of benzene, toluene, ethylbenzene, and xylene (BTEX) include advection, dispersion, dilution from recharge, sorption, volatilization and biodegradation. Of these processes, biodegradation is the only mechanism working to transform contaminants into innocuous byproducts. Intrinsic bioremediation causes measurable changes in ground water chemistry and occurs when indigenous microorganisms work to bring about a reduction in the total mass of contamination in the subsurface without the addition of nutrients. Specifically, concentrations of contaminants, dissolved oxyen, nitrate, iron (II), sulfate, and metnane in ground water change both temporally and spatially as biodegradation proceeds. Patterns and rates of intrinsic bioremediation can vary markedly from site to site depending on governing physical and chemical processes.
The United States Air Force Center for Environmental Excellence - Technology Transfer Division (AFCEE) has developed a protocol for documenting and quantifying intrinsic bioremediation. Based on work performed at 25 Air Force bases and numerous industrial sites using the AFCEE protocol, it is apparent that, on a mass basis, the importance of anaerobic biodegradation greatly exceeds aerobic respiration in the ground water environment over time. Of the anaerobic processes, methanogenesis and sulfate reduction appear to account for the greatest reduction in dissolved BTEX mass, with denitrificaation and iron reduction contributing somewhat less to BTEX attenuation. Ultimately, the relative importance of aerobic respiration, methanogenesis, sulfate reduction, denitrification, and iron reduction depends on the geochemical characteristics of the host ground water.