Bioavailability and Biostabilization of Multicomponent Nonaqueous Phase Liquids in the Subsurface

EPA Grant Number: R825961
Title: Bioavailability and Biostabilization of Multicomponent Nonaqueous Phase Liquids in the Subsurface
Investigators: Illangasekare, Tissa , Bielefeldt, Angela , Ramaswami, Anuradha
Institution: University of Colorado at Boulder
Current Institution: University of Colorado at Boulder , Colorado School of Mines , University of Colorado at Denver
EPA Project Officer: Lasat, Mitch
Project Period: October 1, 1997 through September 30, 2000
Project Amount: $433,441
RFA: EPA/DOE/NSF/ONR - Joint Program On Bioremediation (1997) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management


Traditional environmental strategies have been found to be technologically impracticable at times contaminated with high molecular weight, multi component dense non-aqueous phase liquids (DNAPLs) due to the problems associated with complete mobilization/dissolution of the organic-phase liquid from heterogeneous subsurface systems. This project evaluates the potential of achieving risk reduction at DNAPL-contaminated sites through biological stabilization processes that focus on containing the extent of DNAPL contamination without requiring complete destruction of all the hydrophobic organic components (HOCs) derived from the DNAPL.

The overall goal of this study is to understand key factors that control the bioavailability of high molecular-weight organic contaminants sequestered within multi component DNAPLs entrapped in heterogeneous soil systems, and to optimize these factors for design of an engineered biostabilization system that may be employed to control DNAPL contamination in field situations.


The research will be accomplished in two phases: The first phase will develop rapid screening techniques to define the end-point of DNAPL biostabilization based upon four criteria: microbial biomass, aqueous-phase concentrations of multiple HOCS, aggregate toxicity of the aqueous phase, and composition of the DNAPL residue. The screening tests will also be employed to model biodegradation kinetics for individual HOCs, in the absence of mass transfer constraints, incorporating toxic/inhibitory effects of the DNAPL mixture and its degradation products. The second phase will focus on bioavailability phenomena that control overall biostabilization rates for DNAPLs in the field. The concurrent mass transfer and bioavailability of multiple DNAPL-deprived contaminants will be assessed in independent mass transfer and biotransformation tests. The tests will be conducted at two different spatial scales (l-dimensional bench-scale column and 2-dimensional pilot-scale tank) such that generalized engineering protocols may be developed for the scale-up of bioavailability and biotransformation models from the laboratory to the field. Experimental studies and mathematical models will integrate mass transfer, bioavailability and biokinetic phenomena, all of which can constrain biotransformation rates. The studies will use two real-world DNAPLs, coal tar and a disparate PCB-oil mixture, obtained from field sites at Maryland and at the McClelland Air Force Base, California, respectively. Site-specific soils and geologic data will be used in the column-scale and tank-scale tests, enabling extrapolation to field conditions.

Expected Results:

The proposed research will provide basic knowledge about coupled physical, chemical and microbial processes that control the fate and stabilization of DNAPL-derived contaminants in subsurface environments. The study will result in the development of protocols for scaling-up multi-component bioavailability and biotransformation models from the laboratory to the field. Fundamental research in these areas will enable development of experimental and engineering procedures for implementing biostabilization at field sites contaminated with complex multi component DNAPLs.

Publications and Presentations:

Publications have been submitted on this project: View all 36 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 4 journal articles for this project

Supplemental Keywords:

groundwater and soil contamination, bioavailability, risk management, DNAPL, Bioremediation, modeling, treatment, restoration, innovative technology., RFA, Scientific Discipline, Toxics, Waste, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Bioavailability, Environmental Chemistry, Chemistry, State, HAPS, Fate & Transport, Environmental Microbiology, Microbiology, chemical mixtures, Bioremediation, Groundwater remediation, Engineering, Environmental Engineering, fate and transport, risk-based decisions, NAPL, DNAPL, biostabilization, contaminated sediment, biodegradation, multicomponent nonaqueous phase liquids, chemical transport, subsurface systems, HOCs, contaminants in soil, Maryland (MD), chemical releases, contaminant release, sediments, California (CA)

Progress and Final Reports:

  • 1998 Progress Report
  • 1999 Progress Report
  • Final Report