minewater treatment for direct discharge 081212

Minewater Treatment for Direct Discharge Using Media-based Engineered Treatment SolutionsSeptember 12, 2012

Clean water. Clean earth. That’s our promise.TM l wrtnet.com

Direct Discharge under NPDES Permit

NPDES Program requirements now include specific contaminant limits based on the receiving water in-stream water quality criteria. Recent initiatives are directed toward ensuring

pollution discharge levels are met on a watershed basis.

This means that Federal, State and Tribal derived limits for some constituents can be, and many times are, specified lower than typical drinking water standards. Extreme examples are trace level requirements for

arsenic, radium and selenium below the allowable drinking water concentrations for these metals.

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Sorption Media Treatment

Primary Targeted Contaminants suitable for media sorption. Metals: Arsenic, Molybdenum, Lead, Mercury, Selenium,

Copper, Chromium, Cadmium, Thallium Radionuclides: Uranium, Radium, Gross Alpha emitters

Why. Concentrations of these constituents in most waste

waters are low enough to provide reasonable service volumes between media exchanges.

Media sorption provides the best opportunity to reduce effluent concentrations to extremely low trace levels.

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Zeolite-based Media Systems

Natural zeolite ion exchange properties are well documented and studied. Cation exchange directly allows removal of lead, zinc,

cadmium and copper. Raw natural zeolites for once-through processing of

waste water is very cost effective compared to synthetic ion exchange materials or other adsorbants where removal performance is similar.

Surface modified zeolites have shown effective removal of oxy-anion metal complexes of selenium, manganese, arsenic and chrome from waste streams.

Natural zeolites are easily processed to facilitate their use in water treatment systems.


Natural Zeolite-based Media Systems

Natural zeolites are readily available. The resources are large, well tested and consistent in performance.

There are a number of available technologies that improve sorbent selectivity or increase capacity for specific contaminants.

Technology is proven in municipal and drinking water, nuclear, and industrial water treatment applications and is becoming more common in polishing mine effluents prior to discharge.


Applications

Water Treatment Products Clinoptilolite and chabazite

based products for ion exchange applications

SCM proprietary functionalized mineral based zeolites are fast, reliable, low-cost water treatment alternatives to chemical treatment and activated carbon

NSF 60 Certified for Potable Water Treatment Systems

NSF 50 products for swimming pools

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Types of Zeolites

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St. Cloud Mining Company

Bowie Chabazite

Ash Meadows Clinoptilolite


TYPICAL PROPERTIES

Form Powder or Granules

Color Dark Brown (Dry Brightness 40)

Ring Members 8

Crystal Size - Chabazite Less than 1 micron

Crystallinity + 90%

Density 1.73 g/cm3

Pore Size 4.1 by 3.7 Angstroms

Effective Pore Diameter 4.3 Angstroms

Cavity Size 11.0 by 6.6 Angstroms

Total Pore Volume .468 cm3/g

Surface Area 520.95 m2/g

Crystal Void Volume .47 cm3/cm3

Packing Density Approx. 513kg/m3 (32 lbs/ft3)

SiO2/Al2O3 Ratio Approx. 4:1

MOH's Hardness -5

Moisture as packaged Less than 12% by weight

pH of 1% Dispersion 8.5

Stability pH of 3 through 12

Ion Exchange Capacity 2.50 meq/g

Sorption Capacity Greater than 15 wt.% H2O at 10% R.H.

Anhydrous Sodium Aluminosilicate-Chabazie Zeloite (Powder and Granules)


TYPICAL CHEMICAL ANALYSIS

EXCHANGE OF HEAVY METAL IONS

Weight Percent of Heavy Metals Retained in anhydrous CABSORB After Ion Exchange from a .10 mg/ml solution AgNO3, Pb(NO3)2, CoSO4 and a 0.025 mg/ml solution of CuSO4 at the initial pH indicated for each solution.

SiO2 Al2O3 Fe2O3 CaO MgO Na2O K2O DominantCation

68.10 18.59 2.84 0.27 0.75 8.32 1.12 Na

EXCHANGE SELECTIVITIES

Tl+>Cs+>K+>Ag+>Rb+>NH4+>Pb2+>Na+ = Ba2+>Sr2+>Ca2+>Li+

Anhydrous Sodium Aluminosilicate-Chabazie Zeloite (Powder and Granules)


Hydrous Sodium AluminosilicateClinoptilolite Zeolite

TYPICAL PROPERTIES

Form Granules Color Tan – Green Pore Diameter 4.0 Angstroms Pore Volume 15% Specific Surface Area 40m.2/g. Bulk 45-80 lbs/ft3

760 - 1283 Kg/m3

Solid Density 100 lbs/ft3 1603 Kg/m3

Alkali Stability pH of 7 - 10 Acid Stability ph of 3 - 7 Thermal Stability 1202 degrees F

650 degrees C Ion Exchange Capacity 1.85 milliequivalents/g.


TYPICAL CHEMICAL ANALYSIS

MAJOR EXCHANGEABLE CATIONS

Hydrous Sodium AluminosilicateClinoptilolite Zeolite

SiO2 Al2O3 Fe2O3 CaO MgO Na2O K2O MnO TiO2

69.1 11.9 .7 .8 .4 3.5 3.8 0.02 0.1

Rb+ Na+ Ba+2 Mg+2 Li+ Ag+ Sr+2 Fe+3 K+ Cd+2

Cu+2 Co+3 Cs+ Pb+2 Ca+2 Al+3 NH+4 Zn+2 Hg+2 Cr+3


Typical removal rates for Copper and Zinc.

0.98

0.982

0.984

0.986

0.988

0.99

0.992

0.994

0.996

0.998

0 5 10 15 20 25 30 35 40 45

Volume (L)

Per

cen

t A

dso

rbed

(%

)

Copper Zinc

Adsorption from solution of copper and zinc obtained with Chabazite in once through column operation


Media Sorption Treatment Systems

Media sorption systems are well suited to mining water treatment. Conceptually the process selectively removes

contaminants onto a solid phase media material for safe and convenient disposal, creating no or minimal additional waste streams.

Can be designed to treat small and large (greater than 10.0 MM gal/day treatment streams.−Designs can accommodate long-term and temporary

installations Media sorption can implemented as a complimentary

treatment to existing or additional treatment processes as BACT to assure very low compliance requirements.

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Project Oriented Approach to Water Treatment Problems

Implementing a project approach to particular water treatment objectives. We use typical project cost estimates for determining

whether sorptive media systems are an effective alternative for specific mine water treatment.− Costs associated with initial equipment installations.− Costs of operations and maintenance of the system.− Costs for media disposal.

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The Project Approach to Media-based Treatment

System Configuration Media process vessels

−Flow configurations to match process specific needs• Upflow and Downflow• Pressure vessels and atmospheric vessels• Vertical and horizontal cylindrical vessels

−Media retaining systems• Hydraulic distribution • Uniform media contaminant loading • Bed-depth and media contact time

−Single and multiple treatment stages• Sensitivity of discharge excursions• Maximizing media loading rates

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Operating and Maintenance Minimal pressure requirements Pretreatment to control water quality at inlet to the

process media vessel−Total Suspended Solids handling.• Disposition and disposal of collected solids.

−pH and oxidation/reduction potential.• Changes can drastically affect media removal efficiency and

metal compound solubilities.

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Media disposal Residuals management

−RCRA requirements for Arsenic, Cadmium, Chromium (total), Lead, Mercury and Selenium.• Leachate testing using TCLP

−California disposal options are more stringent.• California WET test procedure for toxicity leachate.

−Media disposal preparation meeting dewatering criteria.• Disposal of solid media generally must meet no free moisture

requirement.• Paint filter test

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Getting a Project Started

Testing various media systems for selection in full-scale. Laboratory-scale tests

−Equilibrium sorptive capacity testing• Stirred batch tests• CEC Testing for select cation contaminants

−Purpose:• Determine the relative sorptive capacity for removal of select

contaminants from solution under equilibrium conditions.• Determines the removal ability of the selected media using

actual test water sampled from the source.−Limitations:• Will not determine the kinetic removal capacity for the media.

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Laboratory Testing

Small-scale column testing Column tests for removal capacity and to determine

potential break-through volumes. Testing is performed by operating a simulated column

and sampling discharge treated water at various throughput increments.

To accelerate the laboratory testing, Rapid Small-scale Column Tests (RSSCT) can be used to reduce total testing times in many cases.−Depending upon the specific media being tested, smaller

size particles are used to duplicate similar diffusion rates for contaminant mass transfer onto the solid phase.

Tests can usually be completed within a weeks time frame to obtain results.

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Small-scale Column Tests

Water In

Feed

1.4

4m

0.4

2m

0.4

2m

E-4

0.4

2m

0.0

7m

0.4

1m

Outlet Tank

F

Distributor plate

Solids Drain

Rotameter

RecycleWater from tap


Small-scale column Tests

Test results can determine expected sorption capacity, removal efficiency under specific contact time, and develop isotherm curves with expected break-through volumes. The data obtained through laboratory column tests is

used to develop scale-up testing to conduct on-site pilot testing.

The data can eliminate media types not suitable for further testing.

Can help to establish the expected dynamic removal rate using a packed column. −This rate is usually the best removal the media will be

expected to achieve in controlled conditions.

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On-site Pilot Testing

Pilot-scale testing is best performed on site Provides site specific results using real-time raw water

samples from the source. Volume requirements for testing a pilot-scale unit usually

prohibit remote testing. Testing of media systems that appear to offer the

best option design of full-scale system. The pilot test should be designed to resemble and partially

simulate full-scale conditions including:−Media operating contact time and hydraulic loading rates.−Number of operating stages to allow comparative data to

estimate full-scale bed depths.− Column design should include media retaining screen design

similar to that envisioned for the full-scale design. −Pretreatment systems operated to provide expected media inlet

conditions.22



Total media contact time estimated from laboratory small-scale column tests. Using isotherm curves developed from the testing, bed depths

can be estimated using design effluent concentrations. On-site pre-treatment used to maximize removal

efficiency of contaminant(s). This usually includes some type of filtration to remove

suspended material from the water stream that will potentially foul sorption media systems.

Many mine water systems are outside nominal range of pH ideally suited to sorption media.

−pH reagents should be carefully selected to reduce the potential for scale formation, of insoluble salts. • Insoluble salt formation invariably co-precipitates metal complexes and

will ultimately reduce sorption on media systems.

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Length of test should be sufficient to establish an operating expectation for changes in water conditions throughout the operating season. Impoundment temperature inversions Blending changes between potential sources Variations in:

−Ambient temperature−Contaminant concentrations−General water quality

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Test results establish the expected full-scale performance of the media for contaminant removal and in many cases the media expected break-through volume. Results are analyzed with two primary objectives:

−To compare and verify original expected results from laboratory based data

−Develop full-scale design parameters for use in system design

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Results from Third Zeolite Pilot Test for Thallium Removal at Hilger Mine

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Tl Conc. (mg/L)

Date Influent Col. 1 Col. 3

5-Dec 1.4 0.005 0.002

10-Dec 2.4 0.015 0.002

16-Dec 0.48 0.75 0.056

17-Dec 0.75 0.86 0.086

19-Dec 1.4 0.96 0.13

22-Dec 2.9 1.2 0.27

24-Dec 3.2 0.87 0.13

26-Dec 2.4 1.3 0.26

29-Dec 1.5 1.7 0.4

31-Dec 0.68 1.7 0.48

2-Jan 1 1.6 0.56

5-Jan 0.5 1.3 0.77

1-Mar

AVERAGE 1.8 0.850 0.148

% RED. 53 92

Det. Limit1 0.003


Pilot Testing for SR-90 Removal

Filter Flow Technology Inc CPFM SystemFlow Rate = 5.7 Liters/minuteResidence = 9.9 minutes

.5 C/Co breakthrough

0

0.5

1

1.5

2

0 500 1000 1500 2000 2500 3000

Column Volume

C/Co

90Sr C/Co

Ca C/Co

Mg C/Co


Pilot Testing for Zinc and Copper Removal

Adsorption results obtained with column when operated in re-circulating mode

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0 50 100 150 200 250

Volume Processed (L)

Rel

ati

ve

Co

nce

ntr

atio

n (

C/C

o)

Copper - Clinoptilolite Zinc - Clinoptilolite

Copper - Chabazite

Zinc - Chabazite


Full-scale Media Removal System Design

Full-scale media designs usually include various features: Multiple treatment stages for consistent water treatment

discharge results Service vessels sized for requisite media contact time and

recommended hydraulic loading rates Service vessels are configured for either upflow or downflow

depending upon specific process requirements Vessels designed to facilitate media removal and

replacement. Many applications are a part of a complete water

treatment system to compliment other treatment technologies or further “polish” treated water to assure trace level effluent values

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Full-scale Media Treatment System


Thallium removal setup at CR Kendall Hilger Mine Montana


Full-scale Media Removal System Design

Pretreatment equipment is incorporated into the design to meet specific media system inlet conditions. Typically pH adjustment and suspended solids removal

systems are employed.

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Spent Media Removal Operation

Media-based treatment systems generally require minimal monitoring and process input changes to maintain consistent operating performance.

Regular effluent sampling for compliance and system performance is used to assess the on-going operation. Obtaining operating data to anticipate future media

exchange frequency. Develops long-term operating trends and notifies

changes to inlet conditions Establishes data necessary to estimate future cost

assessments.

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Media Exchange and Disposal

Media exchanges accomplished with direct transfer of wetted media from service vessel to transport container using pressure or vacuum.

Replacement media fill using similar conveyance systems as removal

Most cases require an up-flow and downflow pre-service rinse operation. Pre-service rinsing accomplished at or near service

flow rate.

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Media Unloading


Media Replacement and Fill



Preparation of media for transport Suitable DOT container with linings depending upon

site disposal requirements−Bag liners−Roll-off dumpsters−Dewatering bins

Waste acceptance criteria documentation Includes TCLP testing results to verify non-hazardous

waste disposal Manifest of media contents

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Preparation for Transportation

Dewatering Packaging



No free moisture requirement for land fill disposal less than 1 percent by volume water

Dewatering Moisture lock and absorbents can be used On-site free moisture draining

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Media Exchange and DisposalRadionuclide Laden Media

Radionuclide laden media disposal requires additional preparation Estimated radionuclide activity determinations Disposal is limited to select disposal locations Special DOT requirements for radioactive waste

material transportation −DOT Class 7 for waste material exceeding specific

radionuclide activity and total activity thresholds

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Media Transportation and Disposal


Thanks for Attending.


Questions and Contact Information

James Arnold, P.E.WRT, [email protected]

Daniel T. EydeSt. Cloud [email protected]

mailto:[email protected]

mailto:[email protected]

minewater treatment for direct discharge 081212

Engineering

clean water

clean earth

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