Final Report: Experimental and Detailed Mathematical Modeling of Diffusion of Contaminants in Fluids

EPA Grant Number: R825513C031
Subproject: this is subproject number 031 , established and managed by the Center Director under grant R825513
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: HSRC (1989) - South and Southwest HSRC
Center Director: Reible, Danny D.
Title: Experimental and Detailed Mathematical Modeling of Diffusion of Contaminants in Fluids
Investigators: Omojola, J. O. , Thibodeaux, Louis J.
Institution: Dillard University , Louisiana State University - Baton Rouge
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 1995 through January 1, 1997
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text |  Recipients Lists
Research Category: Hazardous Substance Research Centers , Land and Waste Management


The research objectives for this work were:
1. Construct basic mathematical model of contaminants in fluids by using two compartment method.
2. Examine effectiveness of thin layer caps on contaminated bed sediment.

Summary/Accomplishments (Outputs/Outcomes):

The method used was a two-compartment model made up of the contaminant and water or soil enclosed in a contained structure. The rate of transport of the contaminants was modeled by a system of first order differential equations.

In the course of this project, we studied the relevant modes of fate and transport processes of contaminants such as molecular diffusion, dispersion, adsorption. description, chemical reaction, biodegradation, sediment deposition and resuspension, advection, erosion, and bioturbation. In addition, the effects of density, thermal, pressure, and concentration gradients were examined. This aspect of our work is to enable us determine the order of importance of these processes as they pertain to the medium in which the transport is taking place.

An alternative to conventional in-situ capping of contaminated bed-sediment was proposed. The
method proposed entails periodically distributing (at 3-month intervals) a thin layer (about 1 cm. in thickness) of silt particles' onto the contaminated bed. Lake Swaytoe in Russia, contaminated with Cesium 137, is used for the case study on theoretical model calculations. Due to Cs-137 adsorption on the silt the cap acts as a barrier, reducing the concentration in the porewater; burial of contaminated solids also occurs with subsequent application of layers. Over time, bioturbation enhanced particle transport mixes clean sediment with contaminated sediment thereby reducing the effectiveness of the cap. Particle interchange is modeled over time to predict concentration levels and to adjust the appropriate time interval for putting on a new layer. The results indicate bed surface porewater Cs-137 concentration can be reduced by over 65% in the first year after four applications of thin layers.

A diagram of our mathematical model appears in Figure 1 while a plot of our calculations for the base case of 1 cm. cap added every three months to a 5 cm. layer of contaminated sediment is shown in Figure 2. It was further demonstrated that the effectiveness of the cap could be further enhanced either with an increase in the cap thickness or the partition coefficient of cap material.

Figure 1
Figure 2

Journal Articles:

No journal articles submitted with this report: View all 2 publications for this subproject

Supplemental Keywords:

contaminated sediments, modeling, and capping., RFA, Scientific Discipline, Air, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Chemical Engineering, air toxics, Contaminated Sediments, Environmental Chemistry, Monitoring/Modeling, Analytical Chemistry, Hazardous Waste, Ecology and Ecosystems, Hazardous, Environmental Engineering, vaporization, environmental technology, sediment treatment, hazardous waste management, hazardous waste treatment, risk assessment, volatile air toxics, contaminated sediment, air pollution, air qialty model, chemical contaminants, contaminated soil, airborne metals, Volatile Organic Compounds (VOCs)

Progress and Final Reports:

Original Abstract
  • 1995

  • Main Center Abstract and Reports:

    R825513    HSRC (1989) - South and Southwest HSRC

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R825513C001 Sediment Resuspension and Contaminant Transport in an Estuary.
    R825513C002 Contaminant Transport Across Cohesive Sediment Interfaces.
    R825513C003 Mobilization and Fate of Inorganic Contaminant due to Resuspension of Cohesive Sediment.
    R825513C004 Source Identification, Transformation, and Transport Processes of N-, O- and S- Containing Organic Chemicals in Wetland and Upland Sediments.
    R825513C005 Mobility and Transport of Radium from Sediment and Waste Pits.
    R825513C006 Anaerobic Biodegradation of 2,4,6-Trinitrotoluene and Other Nitroaromatic Compounds by Clostridium Acetobutylicum.
    R825513C007 Investigation on the Fate and Biotransformation of Hexachlorobutadiene and Chlorobenzenes in a Sediment-Water Estuarine System
    R825513C008 An Investigation of Chemical Transport from Contaminated Sediments through Porous Containment Structures
    R825513C009 Evaluation of Placement and Effectiveness of Sediment Caps
    R825513C010 Coupled Biological and Physicochemical Bed-Sediment Processes
    R825513C011 Pollutant Fluxes to Aquatic Systems via Coupled Biological and Physicochemical Bed-Sediment Processes
    R825513C012 Controls on Metals Partitioning in Contaminated Sediments
    R825513C013 Phytoremediation of TNT Contaminated Soil and Groundwaters
    R825513C014 Sediment-Based Remediation of Hazardous Substances at a Contaminated Military Base
    R825513C015 Effect of Natural Dynamic Changes on Pollutant-Sediment Interaction
    R825513C016 Desorption of Nonpolar Organic Pollutants from Historically Contaminated Sediments and Dredged Materials
    R825513C017 Modeling Air Emissions of Organic Compounds from Contaminated Sediments and Dredged Materials title change in last year to "Long-term Release of Pollutants from Contaminated Sediment Dredged Material"
    R825513C018 Development of an Integrated Optic Interferometer for In-Situ Monitoring of Volatile Hydrocarbons
    R825513C019 Bioremediation of Contaminated Sediments and Dredged Material
    R825513C020 Bioremediation of Sediments Contaminated with Polyaromatic Hydrocarbons
    R825513C021 Role of Particles in Mobilizing Hazardous Chemicals in Urban Runoff
    R825513C022 Particle Transport and Deposit Morphology at the Sediment/Water Interface
    R825513C023 Uptake of Metal Ions from Aqueous Solutions by Sediments
    R825513C024 Bioavailability of Desorption Resistant Hydrocarbons in Sediment-Water Systems.
    R825513C025 Interactive Roles of Microbial and Spartina Populations in Mercury Methylation Processes in Bioremediation of Contaminated Sediments in Salt-Marsh Systems
    R825513C026 Evaluation of Physical-Chemical Methods for Rapid Assessment of the Bioavailability of Moderately Polar Compounds in Sediments
    R825513C027 Freshwater Bioturbators in Riverine Sediments as Enhancers of Contaminant Release
    R825513C028 Characterization of Laguna Madre Contaminated Sediments.
    R825513C029 The Role of Competitive Adsorption of Suspended Sediments in Determining Partitioning and Colloidal Stability.
    R825513C030 Remediation of TNT-Contaminated Soil by Cyanobacterial Mat.
    R825513C031 Experimental and Detailed Mathematical Modeling of Diffusion of Contaminants in Fluids
    R825513C033 Application of Biotechnology in Bioremediation of Contaminated Sediments
    R825513C034 Characterization of PAH's Degrading Bacteria in Coastal Sediments
    R825513C035 Dynamic Aspects of Metal Speciation in the Miami River Sediments in Relation to Particle Size Distribution of Chemical Heterogeneity