Transcript MERCURY CLEANUP THROUGH THE USE OF ELECTROCHEMICAL

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P2-Soil Remediation, Inc.
Electro Petroleum Inc.
MERCURY CLEANUP THROUGH
THE USE OF
ELECTROCHEMICAL
REMEDIATION TECHNOLOGIES
presentation at
“Breaking the Mercury Cycle” Conference
Boston, Massachusetts
May 1–3, 2002
prepared by
Falk Doering, Ph.D., & Niels Doering—P2 Soil Remediation, Inc.
Joe L. Iovenitti, Donald J. Hill, Ph.D., & William A. McIlvride—
Weiss Associates
J. Kenneth Wittle—ElectroPetroleum, Inc.
For additional information, please contact Joe L. Iovenitti
Telephone (510) 450-6141 Fax (510) 547-5043 e-mail [email protected]
DIRECT CURRENT TECHNOLOGIES
Direct Current Technologies
(DCTs)
ElectroChemical Remediation
ElectroChemicalGeoOxidation
(ECGO)
Carbon Dioxide Vacuum Stripping
Wells with Electrolytic Destruction
(CVS-II)
ElectroKinetics
Induced Complexation
(IC)
Geotechnical
Applications
Electro-Kinetic Aided Remediation
(EKAR)
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INDUCED REDOX REACTIONS

How Do They Occur?
Electrodes are placed in the sediment where a low voltage
and low amperage coupled DC/AC field is imposed
 An Induced Polarization (IP) field is created

 the soil acts as a capacitor, discharging and charging
electricity
 electrical discharge cycle causes reduction
 electrical charging cycle causes oxidation
 REDOX reactions occur at a high frequency throughout the
matrix
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INDUCED REDOX REACTIONS

Where Do They Occur?

In the soil under Ex-Situ or In-Situ conditions
Reactions take longer in gravel than fine sand, fine sand
takes longer than clay


Reaction rate is inversely proportional to grain size
At the Pore Scale
Theory = Reactions occur at any and all interfaces within
the soil-water-contaminant system
No pumping or addition of chemicals required
during ECRTs-ECGO or ECRTs-IC.
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ELECTRICAL ENERGY INPUT
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ECRTs—ECGO ELECTRICAL DISCHARGES
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ECRTs PORE SCALE REDOX MODEL
Sorbed water molecule
Soil Particle
or Colloid
Hydrated Anion
Hydrated Cation
Diffuse layer
A zone of redox reaction
Outer Helmholtz Plane
Inner Helmholtz Plane
Hygroscopic Water—
serves as a dielectric
Capacitor Structure
REDOX reactions occur at any and all
interfaces and are believed to result from
electrolysis of water.
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UNION CANAL, SCOTLAND
 Water TDS: ~ 3.5 g/l
mainly sodium chloride
 Main Pollutants:
Elemental and methyl
Hg
 Electrodes: Steel pipes
192 mm OD, each 8 m
long
 Power input: 5.6 kW
 Sediment: silts
 Initial Average Total Hg Concentration: 243 mg\kg
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UNION CANAL, SCOTLAND
220 m3
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UNION CANAL, SCOTLAND
Results (all figures in mg Hg/kg dm)
Sample Location
 After 26 days of remediation 168 lbs
[mg/kg d.m.]
of mostly mercury was deposited on
both electrodes
 Post-remediation average total Hg
Concentration = 6 mg/kg; cleanup
objective was 20 mg/kg
900
800
700
600
500
400
300
200
100
0
T1 anode
T6 anode
T3 middle
T5 middle
T2 cathode
T4 cathode
Outside
Average Concentration
1
33
218
102
282
98
156
809
Remediation Time (days)
12
204
417
36
48
45
9
73
26
11
9
11
6
4
0.7
4
243
119
6.5
Hg
T 1 anode
T 6 anode
T 3 middle
T 5 middle
T 2 cathode
T 4 cathode
outside
0
2
4
6
8
10
12
14
16
18
20
22
days
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26
MONTLUÇON, FRANCE
 350 T of
Sewage Treatment
Plant Sludge Contaminated with
Hg from Dental Amalgams
 Pretreatment
Hg Concentration
= 15 mg\kg to 54 mg/kg;
Cleanup Level = 5 mg/kg
.
 Ex-Situ
Treatment with 2.3 kW
Power Input over 7 Days; Total
Project Electrical Cost ~$40 @
$0.10 \ kW-hr
 Final
Hg concentrations = 0.02
to 0.35 mg/kg, Significantly
Below the Cleanup Level
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Y-12 PLANT, OAK RIDGE
ECRTs Mercury Remediation Laboratory Test
 Soil box: 90 cm x 50 cm x
45 cm with 150 L of
saturated (fresh water)
Y-12 contaminated clay
loam
 Plate electrodes:
80 cm x 32 cm
 Initial Hg concentration:
252 mg/kg
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Y-12 PLANT, OAK RIDGE
ECRTs Laboratory Test

Typically ECRTs Can Not Be Tested in the Laboratory
Due to the Electrical System Resistance

Y-12 Plant Soil Contains 12,000 mg\kg Iron Making It
Highly Electrically Conductive Allowing the ECRTs-IC
Phenomena to Occur

Evidence for the ECRTs-IC Phenomena Is Indicated by
the Migration of Mercury to the Anode which Can Only
Occur Through the Formation of Negative Hg Complexes


Hg concentration increase is >100% at anode
Hg concentration decrease is 60% at cathode
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Y-12 PLANT, OAK RIDGE
 Sampling after 81, 450,
Approximate
Plate Electrode
Positions
and 741 hrs of operation
at sites between anode
and cathode electrodes
 Sampling Locations at
the Anode Face, Quarter
Point, Mid-Point, Three
Quarter Point, and
Cathode Face
Sampling the Test Array
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Y-12 PLANT, OAK RIDGE TEST DATA
ECRTs Laboratory Test—Change in Total Mercury Concentration
600
Total Mercury Concentration (mg/kg)
Pre-Test Concentration
After 81 hr of Operation
500
After 450 hr of Operation
After 741 hr of Operation
400
300
200
100
0
Anode Face
Quarter Point
M id-Point
Three-Quarter Point
Cathode Face
Sampling Location between Anode and Cathode Electrodes
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Y-12 PLANT, OAK RIDGE TEST DATA
ECRTs Laboratory Test—Percent Change in Mercury
Concentration Based on Aqua Regia Leach Test
120%
Baseline
After 81 hrs of Operation
80%
% Change
After 450 hrs of Operation
After 741 hrs of Operation
40%
0%
-40%
-80%
Anode Face
Quarter Point
Mid-Point
Three-Quarter Point
Cathode Face
Sampling Locations between Anode and Cathode Electrodes
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Y-12 PLANT, OAK RIDGE TEST DATA
ECRTs Laboratory Test—TCLP Data
1400
Pre-Test Concentration
After 741 hr of Operation
TCLP Leachate Concentration (mg/L)
1200
Clean-Up Target
1000
800
600
400
200
0
Anode Face
Quarter Point
Mid-Point
Three-Quarter Point
Cathode Face
Sampling Locations between Anode and Cathode Electrodes
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Y-12 PLANT, OAK RIDGE
LABORATORY TEST RESULTS

Hg Contaminated Soils Saturated with Fresh Water
Were Successfully Treated to below the DOE Site
Imposed TCLP Cleanup Level

Mercury species reported by DOE Site to be present include:



mercury chloride, mercury nitrate, mercury sulfide, elemental
mercury, and methyl mercury
No detailed Hg speciation conducted during test reported herein
Laboratory Results Corroborate Fresh and Brackish
Water Field Remediation Results
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Y-12 PLANT, OAK RIDGE
ACKNOWLEDGEMENTS

Work conducted for the U.S. Department of Energy
(DOE) National Environmental Technology
Laboratory (NETL) in cooperation with DOE Oak
Ridge Operations Office and Bechtel Jacobs, LLC,
the DOE Oak Ridge environmental site contractor.

Work completed with assistance from TPG Applied
Technology, ADA Technologies, Inc., and Hazen
Research.
© Weiss Associates, 2002. Reproduction or transmittal in any form or by any means, with prior written permission only.
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FUNDED ECRTs PROJECTS

PCBs in Soils/Sediment at an Upland Site, New
York

Hg, Phenols, PCBs and PAH in Marine Sediments,
Puget Sound, Washington (USEPA SITE Program
Project)

Chlorinated Volatile Organic Compounds in Soil
and Ground Water, NAS Dallas, Texas

PAHs in Lake Superior Fresh Water Sediments,
Minnesota
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