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Natural attenuation of BTEX compounds: model development and field-scale application
1Department of Geology, The University of Alabama, P.O. Box 870338, Tuscaloosa, AL 35487, USA.
Ground Water
|January 8, 2009
Summary
Natural attenuation of benzene, toluene, ethyl benzene, and xylene (BTEX) in groundwater is driven by microbial degradation. This study models BTEX transport and transformation, revealing key factors influencing natural cleanup at petroleum-contaminated sites.
Area of Science:
- Environmental Science
- Hydrogeology
- Environmental Microbiology
Background:
- Petroleum, oil, and lubricants (POL) facilities can release benzene, toluene, ethyl benzene, and xylene (BTEX) into groundwater.
- BTEX compounds are contaminants of concern due to their toxicity and mobility in aquifers.
- Natural attenuation processes, driven by microbial activity, are crucial for remediating BTEX-contaminated sites.
Purpose of the Study:
- To investigate the transport and transformation of dissolved BTEX compounds under natural conditions in a sandy aquifer.
- To develop and apply a reactive flow and transport model to simulate BTEX degradation.
- To quantify the rates of various microbial degradation pathways and identify key factors controlling natural attenuation.
Main Methods:
- Development of a reactive flow and transport model incorporating biochemical multispecies interactions.
- Calibration of the model using field observations of BTEX, oxygen, nitrate, Fe(II), sulfate, and methane plumes.
- Estimation of first-order biodegradation rate constants for aerobic respiration, denitrification, Fe(III) reduction, sulfate reduction, and methanogenesis.
- Sensitivity analysis to identify critical parameters influencing BTEX natural attenuation.
Main Results:
- Model simulations showed good agreement with field observations of BTEX and related plumes.
- Estimated biodegradation rate constants varied across different electron-accepting processes.
- Saturated aquifer thickness, hydraulic conductivity, and reaction rate constants were identified as critical parameters for BTEX natural attenuation.
- Hydraulic conductivity and aquifer thickness significantly impacted the restoration of electron acceptors.
Conclusions:
- Multispecies reactive transport modeling provides a quantitative assessment of BTEX natural attenuation.
- The study highlights the importance of multiple microbial degradation pathways in BTEX remediation.
- Findings are relevant to understanding and managing natural attenuation at numerous petroleum-contaminated sites globally.
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