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Project 3 Abstract
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Metal Removal Capabilities of
Passive Bioreactor Systems:
Effects of Organic Matter and Microbial Population Dynamics
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| Investigator(s): Linda Figueroa, Associate Professor of Environmental
Science and Engineering; Dianne Ahmann, Assistant Professor of Environmental
Science and Engineering; Thomas Wildeman, Professor of Chemistry and Geochemistry;
David Blowes, Professor of Earth Sciences; Kenneth Reardon, Professor of
Chemical Engineering; Kenneth Carlson, Assistant Professor of Civil Engineering;
Charles Shackleford, Professor of Civil Engineering; Nancy DuTeau, Research
Assistant Professor of Microbiology; Sandra Woods, Professor of Civil Engineering |
| Institutions: Colorado School of Mines and Colorado State University |
| EPA Project Officer: Mitch Lasat |
| Project Period: October 1, 2001 - September 30, 2003 |
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| The ability of passive bioreactor systems (anaerobic
wetlands, passive bioreactors and permeable reactive barriers) to
reduce metals from mine drainage has been demonstrated. However, problems
arise with the performance of some passive bioreactor systems. Some
of these problems are cold temperature and stress effects, stable
long-term performance, variable effluent metal concentrations and
nitrate effects on performance. Improvements in performance can be
achieved by a better understanding of how the organic substrate affects
the microbial population distribution and microbial activity, and
the nature of the microbial products (e.g., organic matter), as well
as how the produced OM itself affects metal fate (beneficially or
deleteriously). |
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Dr. Linda Figueroa
presents
at the TMW '02 conference. |
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| Objectives: The overall goal of this project is to evaluate the
effect of organic matter characteristic and types on organic products produced
by the microbial populations, on microbial population distributions and
metal speciation and complexation. To achieve this goal, a research plan
with the following objectives will be followed: 1. To evaluate the physical,
chemical and biological composition of the components used to create the
PBR mixtures, 2. To determine if the organic substrate characteristics affect
the character and concentration of soluble organic matter and metal speciation
and concentration, 3. To determine the variation of microbial population
with time and location, 4. To evaluate the use of mathematical models to
relate metal removal and transport to various system parameters. |
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| Approach: The approach will utilize experimental study in batch
and column systems to test the proposed hypotheses and meet the project
objectives. The project tasks are: 1. Solid phase organic and inorganic
material characterization (physical, chemical and microbial); 2. Batch studies
on the effect of different PBR mixtures; 3. Column studies on the effect
of substrate mixtures and perturbations; 4. Field sampling of anaerobic
wetland and passive bioreactor systems; and 5. Fate and transport modeling. |
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| Expected Results: This project will result in improved designs
of passive bioreactor systems to achieve target metal concentrations to
protect aquatic and human health. |
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| Supplemental Keywords: passive bioreactor, metal, sulfate-reducing
bacteria, microbiology, remediation, mining |