In Situ Chemical
Reduction of
Chlorinated
Compounds
Josephine Molin
Technical Sales Manager
Air Pollution Control
FMC offers SOx and NOx abatement product technologies for coal-fired plants.
Natronx, LLC, EnProveTM sodium sorbents are engineered to remove SO2, SO3, HCl and HF
from stack gases.
FMC’s patented PerNOxide™ technology, licensed from NASA, uses H2O2 to oxidize nitrogen
oxide (NO) and elemental mercury (Hg˚) in flue gas into forms that can be captured by flue-
gas scrubbing devices.
Soil and Groundwater Remediation
FMC’s Klozur® persulfate, Daramend® bioremediation technology, and the EHC® family
of integrated carbon & ZVI technologies, are available globally to provide cost effective
solutions for the remediation of contaminated soil, groundwater, and sediments.
Water Treatment
FMC VigorOx® peracetic acid is a safe and environmentally-benign biocide. FMC can work
directly with customers to understand their unique challenges and develop turnkey solutions
tailored to meet their specific treatment needs while ensuring compliance with individual
state regulations. Our proven water treatment applications include the wastewater and the
oil services industries.
59-01-EIT-DL
ISCR Groundwater
Remediation
Technologies
EHC® family of integrated
carbon & ZVI technologies for
in situ chemical reduction
EHC® ISCR Reagent Composition
EHC is delivered as a dry powder and
includes the following:
• Micro-scale zero valent iron (standard ~40%)
• Controlled-release, food grade, complex
carbon (plant fibers) (standard ~60%)
• Major, minor, and micronutrients
• Food grade organic binding agent
• Sustainable Solution:
o scrap metal
o food production by-products
59-01-EIT-DL
Contaminants Treated
EHC® ISCR Reagent
• Chlorinated Solvents
o PCE, TCE, cDCE, 11DCE, VC
o 1122TeCA, 111TCA, 12DCA
o CT, CF, DCM, CM
• Pesticides
o Toxaphene, Chlordane, Dieldrin, Pentachlorophenol
• Energetics
o TNT, DNT, RDX, HMX, Perchlorate
EHC®-M ISCR Reagent for Metals
• Heavy Metals including As, Cr, Pb, Zn, Cd
59-01-EIT-DL
Mechanism Material Description
Direct Chemical Reduction
ZVI
•Redox reaction at iron surface where solvent gains electrons and iron donates electrons
•Abiotic reaction via beta-elimination
Indirect Chemical Reduction
ZVI •Surface dechlorination by magnetite and green rust precipitates from iron corrosion
Stimulated Biological Reduction
Carbon Substrate
•Anaerobic reductive dechlorination involving fastidious microorganisms
•Strongly influenced by nutritional status and pH of aqueous phase
Enhanced
Thermodynamic Decomposition
ZVI + Organic Carbon
•Energetics of dechlorination are more favorable under lower redox conditions generated by combination of ZVI and organic carbon
EHC® ISCR Treatment Mechanisms
59-01-EIT-DL
Direct Dechlorination Reactions
Figure
Courtesy P.
Tratnyek,
Oregon
Graduate
Institute
Reactions:
Fe0 Fe2+ + 2e-
2H2O 2H+ + 2OH-
2H+ + 2e- H2(g)
R-Cl + H+ + 2e- R-H + Cl-
Carbon Fermentation + ZVI Corrosion:
Multiple Dechlorination Mechanisms
Production of organic acids (VFAs):
•Serves as electron donor for microbial
reduction of CVOCs and other oxidized
species such as O2, NO3, SO4
•The release of acids keeps the pH down
and thereby serve to reduce precipitate
formation on ZVI surfaces
Favorable thermodynamic conditions
for dechlorination:
•Combined oxygen consumption from
carbon fermentation and iron oxidation
Strongly reduced environment
•High electron/H+ pressure
Corrosion H2 generation
Dissolved iron precipitates as reactive
minerals
Hydrocarbon generation
Material
Solid
Organic
Carbon
Iron
Metal
Oxide Film
Ferm
enta
tion
H+
VFA
Downgradient effects
• EHC zone of influence may significantly exceed the direct placement
zone.
• Elevated levels of TOC and Fe and changes to ORP has been
measured up to 70 ft away from the injection zone advection may
be a very important distribution mechanism at some sites.
Solid Particle Bacteria
• Low redox
• Controlled pH
• VFAs, Nutrients
• Ferrous iron
• Hydrogen
ß–Elimination: Main Pathway
Biogenolysis/Hydrogenolysis: Minor Pathway
• Reaction is abiotic reductive dehalogenation; minimizes/eliminates DCE/VC
• Requires direct contact with ZVI surface
• β-elimination is the dominant abiotic pathway (~90%); ZVI generates hydrogen so
some biotic reductive reactions are supported
Direct Chemical Reduction
CVOC Dechlorination Pathways with ZVI
59-01-EIT-DL
EHC® ISCR Installation Methods
Injection Methods
• Direct injection
• Hydraulic fracturing
• Pneumatic fracturing
• Well injections (EHC-L)
Direct Placement
• Trenching
• Excavations
• Deep soil mixing
59-01-EIT-DL
EHC Installation Methods – Direct Placement
Installation of EHC PRB
Placement at bottom of excavation to
treat standing groundwater.
EHC® ISCR Installation Methods
Direct Injection & ChemGrout Mixing
ChemGrouts CG-500 used for mixing and
injections (rated at 20 GPM at 1,000 psi).
59-01-EIT-DL
Preparation of slurry using grout mixer
EHC mixed with water into 30% slurry.
Injection probe with check valve
Allows for either top-down or
bottom-up injection and directs
the slurry laterally into the
subsurface.
A key feature of this probe is that it acts
as a backflow preventer, keeping injection
material IN the ground and not ON the
ground!
59-01-EIT-DL
EHC Conceptual Designs
Source Area/
Hotspot Treatment
Injection PRB for
Plume Control Plume
Treatment
- Dosing: 0.15 to 1% wt/wt
- Spacing: 2 to 5m (DPT)
- Dosing: 0.4 to 1% wt/wt
- Spacing: 2 to 3 m (DPT)
- Dosing: 0.05 to 0.2% wt/wt
-Line Spacing: depends on
linear gw velocity
EHC Case Study – Source Area Treatment
Former Dry Cleaner, Oregon
• Primary CVOCs included chlorinated
ethenes at concentrations up to:
– PCE ~ 22,000 ug/L
– TCE ~ 1,700 ug/L
– DCE ~ 3,100 ug/L
– VC ~ 7 ug/L
• Site-Specific Challenges:
– Low permeability lithology – high degree
of sorbed impacts expected
– Large seasonal variation in groundwater
table (range from ca 2.1 to 4.6 m bgs)
2.5 m smear zone
– Groundwater flow direction change with
season
Test Injection – EHC Injection Distribution Validation
EHC
injection
point
Sampling
locations
Test Injection Soil Cores with EHC Fractures
Injection layout and sampling locations
Figure from Hart Crowser.
-A total of 10,000 lbs (4,649 kg) of EHC was injected into 32 injection points
targeting an area measuring 77 m2 x 6 m deep (from 3 to 9 m bgs).
-Application rate of 0.6% EHC to soil mass.
Source Area Treatment
Results - EHC® Indicator Parameters
0
500
1,000
1,500
2,000
2,500
3,000
0 3 6 9 12 15 18 21 24 27 30 33 36 39
Conc.
(mg/L
)
Time post EHC injection (months)
Total Organic Carbon
0
20
40
60
80
100
120
140
0 3 6 9 12 15 18 21 24
Conc.
(mg/L
)
Time post EHC injection (months)
Ferrous Iron
NW sampling cluster NE sampling cluster
SW sampling cluster SE sampling cluster•Sharp increase in TOC and Fe(II) following injections
confirms effective product placement.
•Dissolved concentrations have gradually decreased over
time but remain above background levels.
•TOC ranging from 3.3 to 18.6 mg/L after 40 months, which
is above the baseline range of <0.8 to 1.8 mg/L.
59-01-EIT-DL
Source Area Treatment Results
Redox indicator parameters
NWsamplingcluster
NEsamplingcluster
SWsamplingcluster
SEsamplingcluster0
510152025303540
0 5 10 15 20 25 30 35 40
Conc.
(mg/L
)
Time post EHC injection (months)
Sulfate
0
5
10
15
20
25
0 5 10 15 20 25 30 35 40
Conc.
(mg/L
)
Time post EHC injection (months)
Methane
-300-250-200-150-100-50
050
100150
0 5 10 15 20 25 30 35 40
OR
P (
mV
)
Time post EHC injection (months)
ORP
0
1
2
3
4
5
6
0 5 10 15 20 25 30 35 40
Conc.
(mg/L
)
Time post EHC injection (months)
Dissolved Oxygen
59-01-EIT-DL
Source Area Treatment Results
CVOCs
0
2,000
4,000
6,000
8,000
1 5 8 12 14 18 22 24 31 34
Conc.
(ug/L
)
Time post injections (months)
SE sampling cluster
0
2,000
4,000
6,000
8,000
10,000
12,000
1 5 8 12 14 18 22 24 31 34
Conc.
(ug/L
)
Time post injections (months)
SW sampling cluster
0
5,000
10,000
15,000
20,000
25,000
30,000
-18 0 1 5 8 12 14 18 22 24 31 34
Conc.
(ug/L
)
Time post injections (months)
NW sampling cluster
0
1,000
2,000
3,000
4,000
5,000
6,000
-18 0 1 5 8 12 14 18 22 24 31 34
Conc.
(ug/L
)
Time post injections (months)
NE sampling cluster
VC
CA
c-DCE
TCE
PCE
59-01-EIT-DL
25
Total CVOCs and Fluctuations in
Groundwater Table 0
1
2
3
4
5
6
7
8
9
101
10
100
1,000
10,000
100,000D
ec-0
6
Ap
r-0
7
Au
g-0
7
Dec
-07
Ap
r-0
8
Au
g-0
8
Dec
-08
Ap
r-0
9
Au
g-0
9
Dec
-09
Depth
to G
roundw
ate
r (m b
gs)
Tota
l C
VO
C C
onc.
(ug/L
)
CVOCs - NW CVOCs - NE CVOCs - SW CVOCs - SE
GW Table - NW GW Table - NE GW Table - SW GW Table - SE
Max: 151 ppb
Max: 54 ppb
Max: 418 ppb
Source Area Treatment
Degradation End Products
0
100
200
300
400
500
600
700
800
0 3 6 9 12 15 18 21 24 27 30 33 36 39
Co
nc.
(ug
/L)
Time post EHC injection (months)
Ethene - NW
Ethane - NW
Ethene - NE
Ethane - NE
Ethene - SW
Ethane - SW
Ethene - SE
Ethane - SE
•An increase in ethene and ethane levels confirms that complete dehalogenation is occurring.
•Ethene levels of up to 760 ug/L were measured in July 2007 (11-month data) 96 percent increase
compared with maximum baseline levels.
•A correlation has been observed between total CVOC concentrations and ethene plus ethane measured
in groundwater following an initial acclimatization period of 7 months.
59-01-EIT-DL
Economics
• A total of 10,000 lbs of EHC was applied at a product cost of $20,000.
• The material cost of using EHC was $1.24/ft3 ($44/m3).
• The injections were completed in 5 days.
• Results of this pilot study have shown that ISCR using the EHC technology offers a safe, effective and cost-efficient remedial solution for dry cleaning and related sites.
• Plume extends 2,600 ft / 800
m from grain elevators.
• Discharges into small creek.
• The bedrock rises to an
elevation of ca 9 ft / 3 m above
the present day water table at
the presumed source area.
• PRB installed down-gradient of
suspected source area in April
2005.
• The PRB is installed as a line
of injection points spaced
approximately 10 ft / 3 m
apart.
• The PRB extends across the
width of the plume and
measures ca 270 ft / 90 m
long.
EHC® PRB Case Study
Plume Treatment Carbon Tet Site - Kansas
Figure courtesy of Malcolm Pirnie Inc.
59-01-EIT-DL
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
0 27 54 81 108 135 162 189 216 243 270
Distance from SBE [ft]
Inje
cti
on
de
pth
[ft
]
EHC® PRB – Plume
Treatment Injection Layout
59-01-EIT-DL
44<1
<1
120067
25<1 <1
19
1575
16
72<1
5.825
<1
EHC Treatment Zone
Monitoring well andCT concentration (ug/L)
N
Property Line
0 300 600
SCALE IN FEET
May 2010
60<1
<1
57062
31<1 <1
21
1635
21
120<1
1334
<1
EHC Treatment Zone
Monitoring well andCT concentration (ug/L)
N
Property Line
0 300 600
SCALE IN FEET
October 2009
70<1
<1
1400130
29<1 <1
21
2117
62
260<1
1589
<1
EHC Treatment Zone
Monitoring well andCT concentration (ug/L)
N
Property Line
0 300 600
SCALE IN FEET
April 2009
150<1
<1
620170
49<1 <1
37
1254
110
490<1
28170
<1
EHC Treatment Zone
Monitoring well andCT concentration (ug/L)
N
Property Line
0 300 600
SCALE IN FEET
October 2008
82<1
<1
1400300
57<1 <1
13
1946
380
650<1
25280
<1
EHC Treatment Zone
Monitoring well andCT concentration (ug/L)
N
Property Line
0 300 600
SCALE IN FEET
April 2008
98<1
<1
1600170
27<1 <1
14
94140
610
540<1
82190
<1
EHC Treatment Zone
Monitoring well andCT concentration (ug/L)
N
Property Line
0 300 600
SCALE IN FEET
August 2007
36<1
<1
2700620
33<1 <1
17
150380
610
410<1
2.485
<1
EHC Treatment Zone
Monitoring well andCT concentration (ug/L)
N
Property Line
0 300 600
SCALE IN FEET
February 2007
47<1
<1
770140
100011 <1
140
49067
280
4606.4
3798
<1
EHC Treatment Zone
Monitoring well andCT concentration (ug/L)
N
Property Line
0 300 600
SCALE IN FEET
March 2005
EHC® PRB - Plume Treatment Results
59-01-EIT-DL
EHC® PRB – Plume Treatment Economics
• A total of 48,000 lbs / 21,800 kg of
EHC was used to create the 270 ft / 90
m long PRB at a product cost of less
than $100,000 $37/ft2 ($395/m2) of
PRB cross-section.
• The installation was completed in 12
days using direct injection.
• So far, the PRB has treated a total of
ca. 2,500,000 ft3 (73,000 m3) of
groundwater during its life-time at a
product cost of $0.04/ft3 ($1.32/m3).
59-01-EIT-DL
EHC®-L – Soluble ISCR Reagent
• EHC -L is a cold-water soluble formulation
of EHC specially designed for injection via
existing wells or hydraulic injection networks.
• EHC -L is delivered in two parts:
(i) a liquid organic carbon emulsion and
(ii) an organo-iron powder.
59-01-EIT-DL
Part 2
Part 1
• Water content will vary with
desired injection volume and
physical conditions.
EHC-M Controlled-release carbon with sulfide, nutrients & micro-scale ZVI
EHC®–M ISCR Reagent for Metals
59-01-EIT-DL
• Reducible metals are
present in natural waters as
anions and oxyanions (e.g.
Cr, As, Se, Mo, U)
• Immobilized via reductive
precipitation with iron
oxides and oxyhydroxides
• Puls and Su, EPA Research
Lab, OK:
Reductive precipitation of
chromium and arsenic
treatment with ZVI PRBs.
Previous Research on In-situ Reductive
Treatment of Dissolved Metals
• Metal cations are present in
natural waters as divalent
cations (e.g. Cu, Zn, Cd, Pb,
Hg, Ni)
• Precipitate as metal sulfides.
• Various carbon substrates used
to microbially mediate
reduction of sulfate present in
the groundwater
• Blowes et al., University of
Waterloo: Organic substrate
PRBs for sulfate reduction and
trace metals treatment in acid
mine drainage.
Amended aquifer
zone.
Solid carbon
source could be
saw dust, wood
chips, plant
fibers.
Previous Research on In-situ Reductive
Treatment of Dissolved Metals
EHC-M Composition
Contains controlled-release organic carbon, micro-scale zero valent iron (ZVI), a source of sulfate and other additives
Treats dissolved trace metals and mixed plumes containing cVOCs and metals
Summary of Treatment Efficiencies
Observed in Internal Lab Tests
Compound Influent
Concentration Range (ug/L)
Observed Removal Efficiency (%)
Antimony 24,500 >99
Arsenic 500 98
Cadmium 11 >99
Chromium 200 >99
Cobalt 210 >99
Copper 86 >99
Lead 64,000 >99
Nickel 350 >99
Zinc 50,400 92
November 5, 2012
www.environmental.fmc.com
Josephine Molin
Technical Sales Manager
FMC Environmental Solutions
Phone: 773.991.9615
www.environmental.fmc.com
Any Questions?
59-01-EIT-DL