Permeable Reactive Barriers for Treatment of Dissolved Metals

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Permeable Reactive Barriers for Treatment of
Dissolved Metals
University of Waterloo D. Blowes, C. Ptacek, L.
Eckel, L. Spink, T. Cihula, S.-W. Jeen École
Polytechnique, Montréal R. Samson, G. Zagury,
I. Cocos University of British Columbia U.
Mayer, R. Williams, R. Amos

• November 24, 2005
• Kananaskis Researcher Retreat

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Overall Goal

• Development of effective methods for passive
  groundwater remediation to protect groundwater
  and surface water resources
• Focus is on dissolved metals

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Research Team

• University of Waterloo
• D. Blowes, C. Ptacek, L. Eckel, L. Spink, T.
  Cihula, S.-W.Jeen
• Ecole Polytechnique (Montreal)
• G. Zagury, R. Samson, I. Cocos, V. Kalnieks,
• University of British Columbia
• U. Mayer, R. Williams, R. Amos

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Key Challenges/Goals

• What materials will provide best performance
  (treatment rate, longevity, costs)?
• What tools are available to assess long-term
  performance?
• What tools are available to assess long-term
  economic advantages?

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Relevant State-of-The-Research

• Permeable reactive barriers for treating
  dissolved metals
• Technology developed at UW (several international
  patents)
• An area of intense international research
• This project is at the leading edge of the field

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Approach

• Develop a laboratory protocol for screening
  reactive materials
• Evaluate performance of reactive materials in the
  field
• Monitor long term performance in the laboratory
  and field using multiple methods
• Develop reactive transport model and simulate
  laboratory and field results
• Develop and apply economic forecasting model

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Stage of Research

• Laboratory testing
• Advanced stage experimental protocols developed
  and being applied
• Field evaluation
• Advanced stage large-scale systems in place and
  long-term monitoring underway
• Modelling
• Advanced stage numerical simulator developed and
  being applied to field systems
• Assessment of long-term limitations to
  technology
• Preliminary stage initial assessments under way
• Evaluation of new reactive mixtures
• Preliminary lab testing underway, field testing
  planned
• Financial Evaluation
• Preliminary economic forecasting model completed
  and demonstration scenarios being developed

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Key Findings/ObservationsMaterial
Characterization

• Low efficiency
• Single carbon source
• Maximum efficiency
• Mixed organic carbon source
• Characterization of organic substrates on an
  individual basis provides insight on carbon
  composition and solubility, but not on ability to
  promote sulfate-reduction and metal removal

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Key Findings/ObservationsField Monitoring
Dissolved Gas Analysis

• Gas exsolution is occurring (N2 and Ar degassing)
• Sulfate reduction is dominant and methanogenesis
  is insignificant
• Gases can be used as indicator for preferential
  flow

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Key Findings/ObservationsLong Term Monitoring
Sulfide Accumulation in Nickel Rim PRB

• Treatment efficiency
• Rapid initial decrease
• Maintained long term at a steady rate

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Key Findings/ObservationsField Monitoring and
Reactive Transport Modeling
distance m

• Simulations are well constrained by combined use
  of pore water, solid phase extraction, and
  dissolved gas data
• Long term evolution can be simulated using a
  multi-modal organic carbon model

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Key Findings/ObservationsEconomic Evaluation
Methods

• Real costs are dependent on a large number of
  factors including
• All internal costs
• Income tax impacts
• Cost of capital
• Image social costs
• Corporate risk management considerations
• Corporate cash flow considerations
• Corporate reporting considerations
• Considering these costs makes PRBs a more
  attractive choice

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Insights on Knowledge Transfer

• Tendency to employ existing approaches, rather
  than innovative technologies, even when it is
  known that the older approaches will not solve
  the problem
• Regulatory acceptability
• Challenges in communicating with clients and
  regulators
• Lower perceived risk
• Larger corporations more open to new technologies

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Opportunities

• Technology application in the resource and
  industrial sectors
• Application of reactive transport modeling to a
  broad range of projects
• Application of dissolved gas method to a broad
  range of projects
• Application of financial decision making software

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Collaborative Interests

• Implementation of new reactive materials
  identified through the CWN project and other
  concurrent research projects
• More extensive application of reactive transport
  modeling for design of remedial systems
• Use of dissolved gases as reaction and transport
  tracers
• Application of the financial decision making
  software in project planning