Superfund Research Program

Coupled Processes in Bioavailability: Enhanced Pollutant Desorption Kinetics in Porous Media Mediated by Bacterial Extracellular Polymers

Project Leaders: Michael L. Shuler, Leonard W. Lion
Grant Number: P42ES005950
Funding Period: 1995 - 2000

Project-Specific Links

Final Progress Reports

Year:   1999 

Toxic metals and polynuclear aromatic hydrocarbon (PAH) compounds are persistent contaminants at many Superfund sites. Project investigators developed a mathematical model to describe PAH desorption, transport and biodegration in porous media. The initial model assumed a gamma distribution of desorption release rate constants and has been expanded so that the size distribution of soil aggregates can be considered. Napthalene and phenanthrene have been used as model PAH compounds. This work has revealed that bacterial polymers have the unusual capacity to simultaneously bind both trace metals and hyrophobic organic compounds. This result suggests that biopolymers will enhance contaminant solubilization in soils contaminated with mixed wastes. The investigators have also demonstrated that soil-bound PAHs are mobilized by amphiphilic polyurethane (APU) polymer nanoparticles. The APU particles are engineered to have hydrophilic exterior and a hydrophobic interior. This enables high mobility in soil, high PAH sorptive capacity and high recovery of APU particles. The experimental systems and mathematical model developed for bacterial polymers are directly applicable to evaluation of the PAH mobilization capabilities of alternative formulations of synthetic nanoparticles.