You are here:
Some Environmental Consequences of a Release of Ethanol to Ground Water
Citation:
WILSON, J. T. Some Environmental Consequences of a Release of Ethanol to Ground Water. Presented at The 14th International Petroleum Environmental Conference, Houston, TX, November 06 - 09, 2007.
Impact/Purpose:
To present information at the 14th International Petroleum Environmental Conference
Description:
Estimates on the concentration of ethanol in ground water as a result of a spill of gasoline containing 10% to 15% ethanol vary from approximately 4,000 mg/L to 15,000 mg/L. Published data on the rate of ethanol biodegradation vary from 2 mg/L per day to greater than 500 mg/L per day. The median rate is near 20 mg/L per day. Under typical conditions, 5,000 mg/L of ethanol would persist from 56 to 500 days. Ethanol degradation will be rapid in the context of ground water flow. Ethanol in ground water can be degraded by sulfate reducing bacteria; biodegradation of 100 mg/liter ethanol will consume 313 mg/L sulfate. Once sulfate is consumed, ethanol can be fermented to produce hydrogen, acetate, and eventually methane; fermentation of 100 mg/liter ethanol can produce 35 mg/L methane. At most ethanol spill sites available concentrations of sulfate, nitrate, and oxygen in ground water will be exhausted. Methane will be the dominant degradation product. Methane concentrations will exceed their solubility in water, and methane will escape to the unsaturated zone. Benzene plumes may be longer when ethanol is also present in the ground water. However, at many spill sites, the increased plume length may be acceptable from the point of view of risk management.