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Bioavailability of Aromatic Hydrocarbons in Saturated Porous Media: The Effects of Chemical Aging and Mass Transfer

EPA Grant Number: R825406
Title: Bioavailability of Aromatic Hydrocarbons in Saturated Porous Media: The Effects of Chemical Aging and Mass Transfer
Investigators: Bouwer, Edward J. , Ball, William P.
Institution: Johns Hopkins University
EPA Project Officer: Stelz, Bill
Project Period: December 6, 1996 through December 5, 1999 (Extended to December 5, 2001)
Project Amount: $439,725
RFA: Environmental Fate and Treatment of Toxics and Hazardous Wastes (1996)
Research Category: Hazardous Waste/Remediation

Description:

The objective of this project is to evaluate, quantify and model the effects of sorption/desorption processes and diffusional mass transfer on the biodegradation of hydrophobic organic contaminants (HOCs) under conditions where aquifer solids and impermeable aggregates of such solids have been exposed to long-term contamination (chemical aging). Furthermore, it is the objective of this research to predict the intrinsic rates of bioremediation of aged compounds based on sorbent and sorbate properties using a coupled desorption/biodegradation model. A series of abiotic and biotic batch and column studies will be conducted to determine and evaluate mass transfer and biodegradation rate parameters. Sorbates proposed for this investigation are: 1,2-dichlorobenzene, naphthalene, and phenanthrene. The proposed sorbents are: organic-free quartz sand (oven fired Ottawa sand), a microporous carbonate aquifer material (Borden sand), and a silty clay loam aquitard material. Batch studies will be used to determine equilibrium isotherms for all sorbate/sorbent combinations and to obtain sorption/desorption rates and biological degradation rates. In these cases, rates will be determined for samples that have been abiotically "aged" for different periods. The kinetics, stoichiometry and bioavailability of the target substrates will then be investigated in column studies which will be used to verify batch data from the sand systems and to obtain rate data in the clay systems. Abiotic and biotic column studies will be conducted using the three model sorbents. Three types of abiotic and biotic columns will be constructed with the chemically aged sorbents: 1) oven fired Ottawa sand, 2) Borden sand, and 3) oven fired Ottawa sand with a uniform distribution of clay spheres. The experimental results will be interpreted by applying appropriate models which incorporate abiotic and biotic rate limitations into the transport and transformation of HOCs in a saturated heterogeneous porous media. The results of this research will complement and augment present knowledge on the qualitative and quantitative effects of chemical aging and mass transfer limited desorption on the bioavailability of HOCs in groundwater aquifers and will provide a framework to better predict groundwater contaminant fate and transport under conditions more representative of actual field conditions. Additionally, data generated from this research will aid those confronted with evaluating the feasibility and efficacy of intrinsic and engineered in situ bioremediation systems. Finally, this research should provide information relevant to establishing proper protocols for estimating biodegradation rate constants that are applicable to field sites.

Publications and Presentations:

Publications have been submitted on this project: View all 11 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 3 journal articles for this project

Supplemental Keywords:

Ecosystem Protection/Environmental Exposure & Risk, Toxics, Scientific Discipline, Waste, HAPS, Bioavailability, Ecological Risk Assessment, Chemistry, Fate & Transport, Environmental Chemistry, National Recommended Water Quality, Bioremediation, soils, sorption kinetics, biodegradation of hydrophobic organic contaminants, biodegradation, fate and transport, toxicity, hydrophobic organic contaminants, environmental toxicant, chemical transport, hydrocarbon, saturated porous material, groundwater, harmful environmental agents, kinetic studies, Phenanthrene, adsorption, contaminated aquifers, hydrocarbon desorption kinetics, mass transfer, bioremediation model, contaminants in soil, Naphthalene, field studies, 1, 2-Dichlorobenzene, aging, soil characterization, aquifer sediments, chemical speciation, saturated porous media, hazardous waste cleanup, mobility

Progress and Final Reports:
1997 Progress Report
1998 Progress Report
1999 Progress Report
2000 Progress Report
Final Report

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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