Pit Lake Characterization Project, Phase III
The research associated with this project was designed to study
and characterize several aspects of the Berkeley Pit Lake system
to gain a better understanding of pit lake systems as a whole. The
project included the following four sub-projects: Bioremediation
Potential of Chromulina Freiburgensis in Culture from the Berkeley
Pit; Berkeley Pit Lake Organic Carbon Remediation Potential; Evaluation
of Potential Impacts by Flooding of the Berkeley Pit on Water Levels
in the Adjacent Alluvial Aquifer; and Photoassisted Electron Transfer
Reactions of Application to Mine Wastewater Cleanup: Selective Recovery
of Metal Values from ARD.
Bioremediation Potential of Chromulina Freiburgensis in
Culture from the Berkeley Pit
Principal Investigator: Dr. Grant Mitman
gmitman@mtech.edu
Although algae are non-detectable in natural Berkeley Pit water
samples, nutrient enriched samples have produced six algae species.
These are Euglena mutabilis Schmitz, Chlorella ellipsoidea Gerneck,
Chromulina freiburgensis Dofl., Chlorella vulgaris Beijerinck, Chlamydomonas
acidophila Negoro, and Pinnularia obscura Krasske var. obscura.
Based on the population potential shown in previous work this project
concentrated on the bioremediation potential of Chromulina freiburgensis.
With nutrient addition, Chromulina freiburgensis reached cell densities
of 1 x 107 algae/mL, which in turn beneficially affected the surrounding
environment. In the nutrient enriched Berkeley Pit water samples,
both bacteria counts and pH increased over a 90 day period. The
algae were not shown to decrease metal ion concentrations in the
water over a 90 day period; however, metal ion concentrations did
decrease over a shorter time frame (24 hours).
Berkeley Pit Lake Organic Carbon Remediation Potential
Principal Investigator: Dr. Douglas Cameron
dcameron@mtech.edu
This portion of the project evaluated readily available organic
waste materials in terms of remediation capacity of Berkeley Pit
water. Four organic amendments were used, and they were sawdust,
lawn clippings, aspen leaves, and treated sewage sludge. Of the
four, the treated sewage sludge showed the greatest bioremediation
potential. Copper was used as a model of soluble metals, and a 1:10
mass ratio of sewage sludge to pit water had greater than 99% removal
efficiency within two days. Neither sulfate, nor iron reached these
removal efficiencies. Iron removal was complicated by oxidation-reduction
reactions of the soluble iron. Further exploration would be required
to fully understand sequestering of soluble iron.
Evaluation of Potential Impacts by Flooding of the Berkeley
Pit on Water Levels in the Adjacent Alluvial Aquifer
Principal Investigator: Dr. John Metesh
jmetesh@mtech.edu
A detailed ground water flow model was constructed to assess impacts
to the alluvial aquifer from the rising water level in the Berkeley
Pit. Should water levels within the Berkeley Pit be left unchecked,
the Pit will cease to act as a sink, but will act as a source instead,
eventually impacting the Silver Bow Creek Basin. A critical water
level of 5,410 feet was established by the EPA, the Montana Department
of Environmental Quality, and the Potentially Responsible Parties.
Upon reaching the critical water level, Berkeley Pit water will
be put through a pump and treat system. As with any system, several
factors affect the alluvial aquifer in the vicinity of the Berkeley
Pit. Along with influences ordinarily input to a groundwater model,
this model focused on leach pads and tailings dams in the vicinity
of the pit, the bedrock aquifer, water level within the Berkeley
Pit, and the two main creeks in the basin, Silver Bow and Blacktail
Creeks. A comparison of modeled to observed data demonstrated that
the model was well calibrated, in spite of working with a very complicated,
dynamic system.
Photoassisted Electron Transfer Reactions of Application
to Mine Wastewater Cleanup: Selective Recovery of Metal Values from
ARD
Principal Investigator: Dr. Courtney Young
cyoung@mtech.edu
Earlier work, (MWTP Activity IV, Projects 3, 3A, and 3B) along with
an interest in exploring interactions of UV light (i.e. sunlight)
led to this study. A bench-scale five stage process was used in
an effort to remove metal ions from Berkeley Pit water. In Stage
I, arsenic, iron, and manganese removal were attempted with selective
UV photooxidation in the presence of H2O2. Arsenic and iron removals
were successful, but it was necessary to add permanganate to oxidize
the manganese. Stage II concentrated on removal of manganese permanganate
formed in Stage I, and it was recommended that other oxidants be
explored to avoid formation of the manganese compound. Sulfide precipitation
successfully removed copper in Stage III, and cadmium in Stage IV.
Zinc removal in Stage IV was not adequate to meet EPA drinking water
standards. Stage V consisted of aluminum precipitation as a hydroxide,
and that too was not adequate to meet drinking water standards.
Activity IV, Project 16
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