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Looking Ahead to 2005
During FY05, the following new projects will be funded under the Mine Waste Technology Program (MWTP).
SUSTAINABILITY OF SUBSTRATES IN SRB BIOREACTORS (MSE)
The key step in sulfate-reducing bioreactor systems is the conversion of sulfate to sulfide and the subsequent precipitation of metal sulfides. The treatment of metal-containing waters in systems that rely on sulfate reduction include wetlands, bioreactors, and permeable reactive barriers. Long-term sustainability has been a key issue for systems based on sulfate reduction. Recent advances in understanding critical components of sulfate-reducing systems has allowed the MWTP to develop a better sulfate-reducing bioreactor system that considers the issues of sustainability of sulfate-reducing activity, flow distribution, maintenance, and placement at remote sites. A modular reactive cartridge design developed by MSE Technology Applications, Inc., and a substrate material developed at the Colorado School of Mines will be evaluated during this project.
PASSIVE TREATMENT TECHNOLOGIES FOR REDUCING METAL LOADING (MSE)
Historical mining practices and the naturally occurring geochemistry in the Coeur d’Alene Basin have resulted in contamination of soil, sediment, surface water, and groundwater. The purpose of this study is to evaluate passive treatment systems side-by-side while treating similar contaminated source water(s). The proposed work will: 1) identify media that will effectively reduce metals loading in Coeur d’Alene Basin; 2) start development of a chemistry based framework for matching media to contaminated water sources; and 3) provide performance data to support scale-up and economic evaluation of technologies. The information generated in this study will aid the U.S. Environment Protection Agency Region 10, Coeur d’Alene Basin Commission, and Idaho Department of Environmental Quality to evaluate and select passive treatment system designs for future implementation.
MODIFIED FERRIHYDRITE FOR ENHANCED REMOVAL OF HEAVY METALS FROM MINE WASTEWATER (MONTANA TECH)
Enhanced removal by adsorption on aluminum-modified ferrihydrite of heavy metals such as cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) will be the focus of this proposed study. Ferrihydrite adsorption is widely used for removing heavy metals from waste and groundwater. A series of laboratory experiments will be conducted to evaluate the adsorptive properties of aluminum modified ferrihydrite with respect to heavy metals. The primary research objectives of the study are as follows: 1) investigate the coprecipitation/adsorption characteristics of ferrihydrite and "aluminum modified ferrihydrite" for the heavy metals Cd, Cu, Ni, and Zn; and 2) investigate the relative stability of the products (compared to unmodified ferrihydrite) that were most effective in removing the heavy metals.
VISUALIZATION OF IN-SITU DOUGLAS FIR ROOTS AND ECTOMYCORRHIZAE IN THE CONTEXT OF PHYTO-REMEDIATION OF ACID MINE WASTES (MONTANA TECH)
Douglas fir (Pseudotsuga menziesii) is a coniferous evergreen tree with the capacity to colonize harsh and severe environments. Douglas fir may have physiological attributes allowing it to survive while being exposed to the potentially toxic levels of metals and low soil pH of acid mine wastes. These attributes may include fine root respiration rates indicative of an active metabolism, root turnover rates, resistance to metal toxicity, and/or ectomycorrhizal fungi associated with Douglas fir roots. For this project, the physiology of ectomycorrhizal Douglas fir will be investigated in the context of contaminated mine wastes and low soil pH. Ultimately, ectomycorrhizal fungi from the Douglas fir tree may be used in biological remediation processes and as a stabilizing agent for mine wastes. The objectives of this research are: 1) to define physiological attributes of Douglas fir trees that allow it to tolerate toxic soils; 2) to determine whether the addition of ectomycorrhizal fungi provides a growth advantage for trees in these types of soils; and 3) to install a minirhizotron to assess the development of Douglas fir root systems.
DUAL ECOSYSTEM ENHANCEMENT: IN-SITU PITLAKE REMEDIATION BY SLAG-SILICATE ADDITION (MONTANA TECH)
This project will investigate the potential for treating acid rock drainage using smelter slag from various inactive smelter sites in Montana. Thermodynamic calculations show that the silicates within basic smelter slags will increase the pH and, thereby, induce precipitation reactions; however, the level of remediation is dependent on the slag-silicates that are used. Because of their different compositions, three smelter slags in particular will be examined: the fayalite slag from the Anaconda Copper Company in Anaconda; the pseudowallastonite/ rankanite slag from Stauffer Chemical near Ramsey; and the olivine slag from ASARCO in East Helena. The initial overall objectives of this research project will be to collect representative slag samples from the three sources, experimentally verify that slag-silicates can be used to remediate acid rock drainage, and determine if the resulting equilibrium pH concurs with the free energy calculations. Kinetics of the reactions need to be relatively fast to be effective.
USE OF BIOMONITORS FOR STUDYING CONTAMINATION IN RESIDENTIAL AREAS AND EFFICACY OF REMEDIATION (MONTANA TECH)
Nearly a century of mining and smelting activities in the Butte/Anaconda area of Montana resulted in widespread contamination throughout southwest Montana. Some of the mining impacted areas have been investigated and remediated as a direct result of the National Priorities List designations of sites in the area. Little is known, however, about the long-term health impact for residential populations exposed to contaminants on a daily basis. This project will perform a novel type of environmental health research to improve our understanding of actual, long-term exposure to widespread elevated metals concentrations in residential areas. This project will use domestic dogs as sentinel species to provide information on exposure patterns. While the overall goal is to improve our understanding of exposure to elevated metals in the environment, the following main objectives have been identified for this project: 1) to develop a simple, inexpensive biomonitoring system to characterize existing exposure patterns to contaminants in the community of Butte, Montana; and 2) to help document the efficacy of localized remediation efforts using the biomonitors.