Annual Meeting Preliminary Program - Full Brochure (PDF) - SME

TECHNICAL PROGRAM
3:25 PM
Microbial Ecology of Iron Cycling in Mined Environments
L. Kirk, L. Bozeman and M. Kozubal; Enviromin, Inc.,
Bozeman, MT
Biogeochemical cycling of iron is critically important to effective management of
acid rock drainage, trace element attenuation, and carbon cycling in mined environments,
but its control requires better understanding of microbial community
structure and metabolism. A data mining approach has been employed to compile
and characterize the geomicrobiology of iron cycling in mining environments
worldwide where geochemistry, microbial populations and metabolic data
have been published. Results show important differences in microbial ecology depending
on mineralogy, aqueous chemistry, pH, and temperature, and suggest
that conceptual geochemical models of iron cycling can be significantly expanded
through inclusion of microbiological data. Analysis of isolate and environmental
genomes is especially valuable in characterizing the metabolic potential
of in situ microbial communities. This work also indicates important gaps in
understanding of geomicrobiology in mining environments, and offers insight
into methods need to address gaps in knowledge about biogeochemical processes
of critical importance to the mining industry.
chair:
2:00 PM
Introductions
environmental:
Mine Water treatment I
2:00 PM • Tuesday, February 26
M. Mierzejewski, CH2MHill, Richmond, VA
2:05 PM
Thermodynamic Constraints on Arsenic and Heavy Metals
Removal from Water with Limestone-Based Material
A. Davis 1 , C. Webb 2 , J. Sorensen 3 and D. Dixon 4 ; 1 Geological
Engineering, South Dakota School of Mines and Technology,
Rapid City, SD; 2 Chemistry Dept., Western Kentucky University,
Bowling Green, KY; 3 RESPEC, Rapid City, SD and 4 Chemical and
Biological Engineering, South Dakota School of Mines and
Technology, Rapid City, SD
Limestone-based material is effective for reducing arsenic concentrations below
the current limit of 10 parts per billion for drinking water, typically resulting in
final concentrations of about 4 to 6 ppb. However, in laboratory and field testing,
further reductions to the 1 ppb range are difficult to achieve with limestone. The
removal mechanism appears to be the formation of a low-solubility precipitate of
hydrated calcium arsenate. Likely reactions and thermodynamic data indicate a
theoretical removal limit of about 2 to 4 ppb for arsenic. Limestone also can reduce
concentrations of cadmium and lead below 1 ppb, resulting in >99% removal
efficiency. Thermodynamic constraints appear to be favorable for reactions
involving the formation of hydrocerussite during lead removal and the formation
of otavite during cadmium removal.
2:25 PM
Targeted Removal of Molybdenum, Radium, Uranium and
Selenium from a Mining
H. Liang and J. Tamburini; Tetra Tech, Denver, CO
Although uranium, radium, molybdenum, and selenium occur naturally and can
be found in waters throughout many parts of the world, ingesting water containing
these substances above established concentrations is considered harmful to
human health and can also harm aquatic life. Therefore, successful treatment and
removal of these toxicants is crucial to protecting human and environmental
health. This presentation will highlight research conducted at a water treatment
plant where optimization of conventional treatment processes such as lime softening
and ferric coagulation led to the successful treatment of all four inorganic
contaminants to their target levels. Because uranium, molybdenum, and selenium
all undergo complex speciation chemistry in aqueous solution, much of the
presentation will focus on details of the water chemistry and speciation considerations
for optimizing the removal of these contaminants. Both bench scale tests
and full scale water treatment plant data and analyses will be presented, and the
rationales for the refinement of the inorganic contaminants removal treatment
processes will be discussed.
2:45 PM
Design and Construction of Twin-PRBs to Intercept Arsenic in a
Former Arroyo
J. Horst 1 , G. Leone 2 and A. Griffin 3 ; 1 ARCADIS, Newtown, PA;
2
ARCADIS, Denver, CO and 3 ARCADIS, Seattle, WA
The 100+ year history of operation at a former lead and copper smelter has resulted
in groundwater across most of the site footprint being impacted primarily
with arsenic. The highest concentrations of arsenic and the majority of groundwater
flow are both focused along former (now buried) arroyos. These features
represent the greatest contribution of contaminant mass flux toward off- site receptors,
and are the key to an integrated strategy for groundwater restoration.
With groundwater seepage velocities ranging between approximately 4 and 10
feet per day, one part of that strategy involved the use of sequential permeable reactive
barriers to reduce contaminant flux toward off-site receptors. This presentation
will review the pre-design, design, and final configuration of a pair of test
barriers. It will also review the construction of the barriers and present some
post-construction performance data.
3:05 PM
Successful Negotiation of Natural Attenuation for Arsenic Using
the EPA Framework
J. Horst 1 and M. Gentile 2 ; 1 ARCADIS, Newtown, PA and
2
ARCADIS, San Francisco, CA
EPA recently released a new framework for supporting natural attenuation
demonstrations associated with metals and other inorganics. This framework
was applied for a site with an arsenic plume in groundwater, sourced by the flushing
of residual organics from beneath a former waste repository. Natural
biodegradation of these organics resulted in an anaerobic environment and
caused naturally occurring arsenic in the aquifer matrix to dissolve into groundwater
via reductive dissolution. This presentation will review the details of a
phased biogeochemical evaluation that included geochemical analysis of aquifer
solids and identification of precedents at other EPA-lead sites, and summarize
the demonstration that supported EPA approval of a change in remedy from
pump and treat to MNA.
3:25 PM
Constructed Wetland Treatment Systems for Mine Drainage Can
They Really Provide Green and Sustainable Solutions?
P. Eger 1 and C. KairiesBeatty 2 ; 1 Global Minerals Engineering,
Hibbing, MN and 2 Winona State University, Winona, MN
The use of wetlands to treat mine drainage has become increasingly common.
They offer the promise of a green and sustainable solution, but how long will
they really work? Treatment lifetime is a function of the metal removal processes.
In surface flow wetlands, trace metals can be removed from neutral mine
drainage by reactions with the organic substrate. Over 90% of the copper and
nickel have been removed in these systems in Minnesota. The primary removal
processes include adsorption, ion exchange and complexation. These processes
are finite since they depend on the existence of suitable removal sites. Removal
will cease unless new removal sites are generated. Two wetlands in northeastern
Minnesota have been treating mine drainage for almost 20 years and are believed
to be the oldest wetlands treating metal mine drainage in the United States.
Treatment lifetime has been estimated to exceed a hundred years. At one of the
wetlands, the annual production of new removal sites has been estimated to be
equal to the annual metal input. As a result, metal removal should theoretically
continue indefinitely resulting in a green and sustainable solution.
This is the Technical Program as of September 1, 2012. IT IS SUBJECT TO CHANGE.
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Please see the Onsite Program for final details.