9/25/2013
Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E. 1
Short Course: Water Management for Mining
Recommended Methodology and Processes for Mine Water Treatment
November 4, 2008
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Presentation Outline
Steps in Selecting a Treatment Process
Potential Treatment Technologies
Mine Water Applications
Specific Contaminants
Recommendations
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Steps in Selecting a Process
Explore/confirm design criteria
Review potential treatment technologies
Develop process flow sheet
Develop budgetary capital and operating
costs
Perform bench and/or pilot tests
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Design Criteria
1. Flow
Maximum (design capacity)
Average (for determining operating costs)
2. Influent concentrations
Are they already known?
How well can they be estimated/modeled?
3. Effluent concentrations
Are permit limits already established?
If not, can they be estimated?
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Potential Treatment Technologies
Physical
Chemical
Biological
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Physical Treatment Technologies
Clarification
Filtration
Membranes
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Clarification
Multiple processes to remove particles in
suspension:
Coagulation/flocculation
Settling
May use sludge recycle
Will not remove dissolved contaminants
Need a disposal site for sludge
Clarifier centerwell at Central Treatment Plant (Kellogg, ID)
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Mark Reinsel, Ph.D., P.E.
Clarifier overflow at Central Treatment Plant (Kellogg, ID)
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Filtration
Bag filters
Cartridge filters
Sand filters
Multimedia filters
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Multimedia Filters
Coarse but light on top, fine but heavy on
the bottom
Typically anthracite, sand and garnet
Automated operation
Downflow operation, upflow backwash
Backwash via DP, timer or manually
1000-gpm multimedia system at Lucky Friday Mine (Mullan, ID)
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Mark Reinsel, Ph.D., P.E.
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Membrane Processes
Microfiltration (MF)
Ultrafiltration (UF)
Nanofiltration (NF)
Reverse osmosis (RO)
Electrodialysis/electrodialysis reversal
(EDR)
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Microfiltration
Most common membrane process
Provides “sterile filtration”
Pore sizes are 0.05 to 3 microns
Removes most suspended solids but no
dissolved contaminants
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Ultrafiltration
Removes colloidal particles, polymers and
bio-molecules
Pore sizes are 0.003 to 0.1 micron
Pressure of 30-150 psi
Also does not remove dissolved
contaminants
500-gpm UF system at Montanore Mine (Libby, MT)
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Nanofiltration
Pore sizes are 0.001 to 0.006 microns
Feed pressure may be up to 200 psi
Removes solids, bacteria, high-MW
contaminants, and divalent or larger ions
(e.g., sulfate)
Will not remove monovalent ions (e.g.,
nitrate)
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Reverse Osmosis
Pore sizes are 0.0001 to 0.001 microns
Feed pressure may be up to 1000 psi
Removes solids, bacteria, viruses and
dissolved solids
Removes (“rejects”) 95-99% of inorganic
salts and charged organics
Higher-valence ions are better-rejected
Spiral Cartridge Configuration
CONCENTRATE
PRESSURE VESSEL BRINE
SEAL
COUPLING
FEED FLOW
PERMEATE PERMEATE
COLLECTION
TUBE
Schematic Cross-Section of Thin Film
Composite R.O. Membrane
Polyamide
Polysulfone
Ultrathin Barrier Layer
0.2 micron
40 micron
120 micron Reinforcing Fabric
Microporous
Polysulfone
RO Disadvantages
Produces high-volume, continuous waste stream
Can be energy-intensive
Removal of monovalent ions such as nitrate may
be limited
Will not remove dissolved gases (e.g., ammonia)
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Mark Reinsel, Ph.D., P.E.
Chemical Treatment
Technologies
Hydroxide precipitation
Sulfide precipitation
Oxidation/reduction
Ion exchange
Natural zeolites
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Mark Reinsel, Ph.D., P.E.
Hydroxide Precipitation
Typically use lime to increase pH
Can be hydrated lime or pebble lime (slaker)
Can also use caustic soda (liquid), soda ash or
magnesium hydroxide
pH target depends upon contaminants of
concern
Co-precipitation can increase removal
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Central Treatment Plant in Kellogg, Idaho
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Aeration Basin at Central Treatment Plant
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Sulfide Precipitation
Typically used as “polishing” step for low metals
concentrations
Will achieve lower levels than hydroxide ppt.
Can use sodium sulfide or hydrosulfide (NaHS)
Need little reagent and low retention time
Perform at neutral-to-alkaline pH to avoid H2S
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Oxidation/Reduction
May be required to transform contaminants into
less-soluble form
Arsenic: Add oxidizing agents such as chlorine,
hydrogen peroxide, ozone, permanganate
Chromium, selenium: Add reducing agents such
as sodium bisulfite or metabisulfite
Reaction is quite rapid
Will add TDS
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Ion Exchange (IX)
Specific resins available for dissolved metals,
arsenic, nitrate
Sodium and chloride are exchanged for
contaminants removed
Several resin manufacturers available
Resin is expensive but can be regenerated (on-
site or off-site)
Waste stream is typically much less than RO
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
WATER SOFTENER
RESIN IN THE Ca+2 FORM
RESIN IN THE Mg+2 FORM
RESIN IN THE Na+ FORM
WATER W/ CaCl2, NaHCO3,
MgSO4
WATER W/ NaCl, NaHCO3,
Na2SO4
Typical Ion Exchange Resin
Capacities
Weak Acid Cation - 45-60 kgr/ft3
Strong Acid Cation - 12-30 kgr/ft3
Weak Base Anion - 19-28 kgr/ft3
Strong Base Anion I - 10-18 kgr/ft3
Strong Base Anion II - 18-22 kgr/ft3
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
IX Regeneration
Regenerate with acid, base and/or salt,
depending on the resin
Frequency depends upon contaminants,
feed water quality and discharge limits
Use co-current or countercurrent
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Natural Zeolites
Can be used for ammonia removal
Also have a high selectivity for thallium
Much less expensive than IX resin
Regenerate with salt
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Biological Treatment
Can be used for the following contaminants:
Organics
Ammonia
Nitrate
Selenium
Sulfate
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Biological Treatment Technologies
Attached growth systems
Suspended growth systems
Membrane bioreactors
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Attached Growth Systems
Bacteria are attached to a surface or media
Biofilm provides a very robust process
Very resilient to changes in flow, pH,
concentrations, etc.
Best choice for high concentrations
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Suspended Growth Systems
Commonly used in municipal treatment
systems (activated sludge)
Often used for nutrient removal (N and P)
Nitrification and denitrification
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Membrane Bioreactors
Combine suspended growth biological
treatment with MF or UF
Membrane replaces clarifier and/or
multimedia filters
High biomass concentration/small footprint
Becoming more popular
Biological treatment system at Key Mine (Republic, WA)
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Biological nitrate removal system at Stillwater Mine (Nye, MT)
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
0
5
10
15
20
25
30
35
10/10/06 1/18/07 4/28/07 8/6/07 11/14/07 2/22/08 6/1/08 9/9/08
mg
/l
Date
Nitrate levels at the Key bio-treatment system
NO3- in NO3- out
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Mark Reinsel, Ph.D., P.E.
0
200
400
600
800
1000
1200
10-Oct-06 18-Jan-07 28-Apr-07 6-Aug-07 14-Nov-07 22-Feb-08 1-Jun-08 9-Sep-08
mg
/l
Date
Sulfate levels at the Key bio-treatment system
SO4 in
SO4 out
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Typical Contaminants of Concern in Mining Waters
Suspended metals
Dissolved metals
Nitrate
Ammonia
Arsenic
Sulfate
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Flow Sheet and Costs
Could develop for more than one option
Capital costs
Operating costs
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Bench/Pilot Testing
Will determine whether selected technology
can meet discharge limits
Can provide valuable information for full-
scale capital and operating costs
May be required by agencies
Bench testing is simpler, shorter and less
expensive than pilot testing
Jar tests or column tests?
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Possible Jar Tests
Chemical precipitation
Coagulation/flocculation
IX
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Possible Column Tests
Leach testing for nitrate/ammonia
IX
Biological
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Apex Engineering, PLLC
Mark Reinsel, Ph.D., P.E.
Recommendations Dissolved metals
Hydroxide ppt. or sulfide ppt. or IX
Nitrate
Denitrification (attached growth) in almost all cases
Ammonia
Nitrification or zeolites or breakpoint chlorination
Arsenic
Iron addition/filtration or iron adsorption or IX
Sulfate
Biological (attached growth) or NF