Evaluation of the Potential for Complete Bioremediation of NAPL-Contaminated Soils Containing Polycyclic Aromatic Hydrocarbons(PAHs):
Catherine A. Peters , Princeton University.


Goal:


The goal of this study is to investigate the bioavailability and biodegradation of multicomponent non-aqueous phase liquid contaminants(NAPLs) containing polycyclic aromatic hydrocarbons (PAHs). This information is used to evaluate bioremediation, via natural attenuation, on the basis of risk reduction.


Rationale:


Polycyclic aromatic hydrocarbons (PAHs) are commonly associated with multicomponent organic contaminants such as coal tar, creosote, and diesel fuel, which exist in the form of non-aqueous phase liquids (NAPLs). The development and widespread application of bioremediation is limited by a lack of full understanding of the chemical, physical, and microbiological interactions that govern the behavior of a multiphase and chemically heterogeneous organic contaminant. This lack of knowledge hinders efficient design of redemption schemes, and inhibits our ability to make predictions of process effectiveness and assess reduction in risk.


Approach:


This project was designed to study the interactions between the physical, chemical, and microbiological processes in two-phase systems containing water and a multicomponent NAPL containing PAHs. The project had three tracks:

  1. Study of multisubstrate biodegradation kinetics for PAHs in aqueous phase aerobic systems,
  2. A thermodynamic analysis of PAH-NAPL phase stability, and
  3. Study of long term composition dynamics and risk assessment in multicomponent NAPL/water systems subject to dissolution, biodegradation, flushing, and precipitation. A novel aspect of this work is the use of synthetic NAPLs as model organic liquids to simulate multicomponent contaminants such as coal tar, which permits control in experimental design and analytical characterization.

Status:


This project will be completed in January 1997. Two years of funding from the NHSRC has been requested for continuation and extension of this work in a new project, R-69 "Toward a Risk-Based Model for Bioremediation of Multicomponent NAPL Contaminants". This project is designed to extend the current work by

  1. Integrating recent biodegradation and thermodynamic parameters into a comprehensive model, and by
  2. Account for subsurface transport modeling to more realistically reflect risk.

Clients/
Users:


The information gained from this study will ultimately serve useful in design of redemption technologies and risk assessment. This information is valuable to the practitioners in the environmental industry, as well as to regulators.