In Situ Chemical
Oxidation:
Performance, Practice, and Pitfalls
Richard A. Brown, Ph.D.
ERM , Inc.
February 25, 2003
ISCO Presentation Topics
Word Slide Sample (36pt)
Overview of ISCO (In Situ Chemical Oxidation)
What oxidants are available
How are they applied
How to decide which to use
Cost
Performance
Designing an ISCO Project
Promoting Readiness through Environmental Stewardship
2
Available Oxidants
Word Slide Sample (36pt)
Ozone
Hydrogen Peroxide
Calcium Peroxide
Sodium Persulfate
Sodium/Potassium Permanganate
Promoting Readiness through Environmental Stewardship
Stewardship
3
Ozone
Word Slide Sample (36pt)
Molecular Weight - 48g Equiv. Weight - 24g
Solubility - 600 mg/L
Availability – On site generation
3-5% Air
8-12% O2
Reactions
Oxidation
O3 + 2H + + 2e - fi O2 + H2O Eo = 2.07v
2OH. + 2H+ + 2e- fi 2H2O Eo = 2.76v
Hydroxyl Radical Formation
O3 + H2O fi O2 + 2OH . (Slow)
2O3 + 3H 2O2 fi 4O2 + 2OH. + 2H2O (Fast)
Decomposition
2O3 fi 3O2
4HO. fi 2H2O + O 2
Promoting Readiness through Environmental Stewardship
4
Hydrogen Peroxide
Word Slide Sample (36pt)
Molecular Weight- 34g Equiv. Weight - 17g, 34g (OH•)
Solubility - Miscible
Availability - 30%, 50% Solutions
Reactions
Oxidation
2OH. + 2H+ + 2e- fi 2H2O Eo = 2.76v
H2O2 + 2H + + 2e- fi 2H2O Eo = 1.77v
HO2- + H2O + 2e- fi 3OH- Eo = 0.88v
Hydroxyl Radical Formation
H2O2 + Fe+2 fi Fe+3 + OH. + OH­
2O3 + 3H 2O2 fi 4O2 + 2OH. + 2H2O
Decomposition
2H2O2 fi 2H2O + O2 + D (Above 11% steam is formed)
4HO. fi 2H2O + O2
Promoting Readiness through Environmental Stewardship
Stewardship
5
Calcium Peroxide
Word Slide Sample (36pt)
Molecular Weight- 72g Equiv. Weight - 36g
Solubility – Slightly Soluble
Availability – Powder 75% Purity
Reactions
Oxidation
CaO2 + 2H2O + 2e - fi Ca(OH)2 + 2OH- Eo = 0.9
HO2- + H2O + 2e- fi 3OH- Eo = 0.88v
Reduction:
HO2- + OH- fi O2 + H2O + 2e ­
Hydrolysis
CaO2 + H2O + OH-fi Ca(OH)2 + HO2
-
Decomposition
2CaO 2 + 2H2O fi 2Ca(OH)2 + O2 + D
Promoting Readiness through Environmental Stewardship
Stewardship
6
Sodium Persulfate
Word Slide Sample (36pt)
Molecular Weight- 238.05g Equiv. Weight - 119.02g
Solubility - 56 g/100 mL
Availability – Crystalline Solid
Reactions
Oxidation
S2O8= + 2e- fi 2SO4= Eo 2.01v
HSO5- + 2H+ + 2e - fi HSO4- + H 2O Eo 1.8v EST
Sulfate Radical Formation
SO4-. + e- fi SO4= Eo = 2.5vEST
S2O8= fi 2SO4-.
Decomposition
2Na2S2O8 + 2H 2O fi O2 + 2H2SO4 + 2Na2SO4
Hydrolysis
Na2S2O8 + H 2O fi NaHSO4 + NaHSO5
Promoting Readiness through Environmental Stewardship
7
Permanganate (Na/K)
Word Slide Sample (36pt)
Molecular Weight- 158.04g K; 141.9 Na
Equivalent Weight - 52.6g K; 47.3 Na
Solubility - K 64g/l @ 20oC; Na >400 g/L @ 20oC
Availability K Purple Crystalline Solid;
Na – 40% Solution
Reactions
Oxidation
MnO4- + 4H + + 3e - fi MnO2 + 2H2O Eo = 1.695v
Decomposition
4KMnO 4 + 4H+ fi 3O2 +2H 2O + 4MnO 2 + 4K+
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8
Application Methods
Word Slide Sample (36pt)
Circulation
Emplacement
Oxidant
Oxidant
Groundwater Flow
T1
T2
T3
T4
Injection Radius
T5
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9
Circulation Methods
Word Slide Sample (36pt)
�
Injection Only
�
Galleries
� Wells
�
�
Vertical
Horizontal
�
Injection & Recovery
�
Galleries & Wells
� Trenches
� Conventional Wells
�
�
Trenches
� Direct injection
�
�
Vertical
Horizontal
Recirculation Wells
Promoting Readiness through Environmental Stewardship
Stewardship
10
Emplacement Methods
Word Slide Sample (36pt)
�
Soil mixing
�
�
�
�
Power
Back-hoe, Excavator
� MITU (Trencher)
� Augers
Pressurized well injection
Geoprobe injection
Pneumatic fracturing
�
Channel creation
� Direct injection
�
Hydraulic fracturing
�
Channel creation
� Direct injection
Jet grouting
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Stewardship
11
Push Tool Injection
Word Slide Sample (36pt)
Sequential Injection
Injection Tip Detail
1.25-inch Drive Stem
Upper Hollow Packer
12-inches
Perforated Drive
Stem
24-inches
10-Slot Continuous
Wire Wound Screen
Drive Point
3-inches
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Stewardship
12
Reactivity of Oxidants
Word Slide Sample (36pt)
Peroxide, Old
Fenton's
Amenable
CVOC's
PCE, TCE,
DCE, VC, CB
Peroxide, New
Fenton's
Calcium
Peroxide
PCE, TCE,
DCE, VC, CB
PCE,TCE,
DCE, VC, CB
Oxidant
Potassium
Permanganate
PCE, TCE,
DCE, VC,
Sodium
Permanganate
PCE, TCE,
DCE, VC,
Sodium
Persulfate, Fe
PCE, TCE,
DCE, VC, CB
Reluctant
CVOCs
DCA, CH2Cl2
DCA, CH2Cl2
TCA, CH2Cl2
Recalcitrant
CVOCs
TCA, CT,
CHCl3
TCA, CT,
CHCl3
CT, CHCl 3
TCA, CT,
CHCl3, DCA,
CB, CH2Cl 2
TCA, CT,
CHCl3, DCA,
CB, CH2Cl 2
DCA, CH2Cl2,
CHCl3
TCA, CT
Sodium
All CVOCs
Persulfate, Heat
Promoting Readiness through Environmental Stewardship
Stewardship
13
Reactivity of Oxidants
Word Slide Sample (36pt)
Peroxide, Old Fenton's
Peroxide, New Fenton's
Potassium Permanganate
Sodium Permanganate
Sodium Persulfate, Fe
Sodium Persulfate, Heat
Ozone
B
H
H
NR
NR
H
H
M
TEX
H
H
H
H
H
H
M
PAHs
M
M
H
H
M
H
H
Phenols Explosives
H
M
H
M
H
H
H
H
H
M
H
H
H
H
PCBs
L
L
L
L
L
H
H
Pesticides
L
L
M
M
M
H
H
Heated Persulfate is the most reactive oxidant
Promoting Readiness through Environmental Stewardship
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14
Oxidant Usage
Word Slide Sample (36pt)
[Oxidant]Required =
[Stoichiometric Demand]Contaminant +
[Soil Oxidant Demand] +
[Metals]Red
[Organic Carbon]Oxidizable
�
[Decomposition]Oxidant
Decomposition and SOD are critical
and often overlooked factors
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15
Soil Demand (Ave), Kg/m3
SOD Soil Oxidant Demand
Word Slide Sample (36pt)
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
O3
S2O8
H2O2
OH.
MnO4
Promoting Readiness through Environmental Stewardship
16
Decomposition, %/Day
Decomposition Rates
Word Slide Sample (36pt)
100
90
80
70
60
50
40
30
20
10
0
HO.
H2O2
O3
S2O8
MnO4
Promoting Readiness through Environmental Stewardship
Stewardship
17
Comparison of Oxidants
Word Slide Sample (36pt)
Oxidant
Wt of
Oxidant Cost
1000 Chief Advavantage
Cost
$/1000Equiv
Equiv, Lb
$/Lb
Limitations
Equivalent
Weight
Peroxide, Old
Fenton's
Stability (10-95%
decomp/hr), low pH
34
$0.75
$56
75
Reactivity, costs
Peroxide, New
Fenton's
Stability
(10-50% decomp/hr)
34
$0.75
$56
75
Reactivity, costs, pH
Calcium
Peroxide
Potassium
Permanganate
Sodium
Permanganate
Not Soluble,
Reaction Speed
36
$3.00
$237
105.7
Stability
Soil oxidant demand
52.6
$1.40
$162
115.8
Ease of use,
Soil oxidant demand
47.3
$5.95
$620
104.2
Ease of use,
Sodium
Persulfate, Fe
Stability (10-25%
decomp/wk), low pH
119
$1.08
$283
262
No SOD, reactivity
Stability (20-50%
decomp/wk), low
pH, heating costs
119
$283
262
Reactivity
Oxidant
Sodium
Persulfate, Heat
$1.08
Promoting Readiness through Environmental Stewardship
Stewardship
18
Comparison of Oxidants
Word Slide Sample (36pt)
Oxidant
Cost/1000
Equivalents
Hydrogen Peroxide
Potassium Permanganate
Sodium Permaganate
Sodium Persulfate
Calcium Peroxide
Ozone
$56
$162
$619
$262
$237
$42
Cost @ Max Cost @ Min
Decomp
Decomp
$1,120
$165
$625
$350
$249
$55
$70
$162
$619
$284
$239
$45
Peroxide is cheapest oxidant if it is stable.
Promoting Readiness through Environmental Stewardship
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19
Comparison of Oxidants
Word Slide Sample (36pt)
Impact of SOD on Costs
Oxidant
Cost
$/Lb.
Sodium Persulfate, Low SOD
Sodium Persulfate, High SOD
Potassium Permanganate, Low SOD
Potassium Permanganate, High SOD
1.10
1.10
1.50
1.50
10 mg/L
0.58
0.58
0.40
6.00
Chemical Cost, $/yd 3
(Xylene)
50 mg/Kg 1000 mg/Kg
8.70
164
8.70
164
3.59
92.1
9.19
97.2
Notes: Low SOD 0.1 g/kg, High SOD 3 g/kg
High SOD affects Permanganate economics
Promoting Readiness through Environmental Stewardship
20
Comparison of Oxidants
Word Slide Sample (36pt)
Oxidant
Solubility
Hydrogen Peroxide
Miscible
Potassium Permanganate
6.40%
Sodium Permaganate
40%
Sodium Persulfate
56%
Calcium Peroxide
Insol.
Ozone
600 mg/L
Maxium Mass
Delivery, Kg/1000 L
Maxium Mass Delivery,
K Eq/1000 L
100 (11%)
64
400
560
100 (Slurry)
0.6
3
1.2
9.36
4.7
2.7
0.025
Mass delivery is a function of solubility and
equivalent weight
Promoting Readiness through Environmental Stewardship
Stewardship
21
Comparison of Oxidants
Word Slide Sample (36pt)
Oxidant
Hydrogen Peroxide*
Calcium Peroxide
Potassium Permanganate
Sodium Permaganate
Sodium Persulfate
Ozone
Oxidant
Hydrogen Peroxide
Calcium Peroxide
Potassium Permanganate
Sodium Permaganate
Sodium Persulfate
Ozone
T 1/2 @ Max
Decomp
10 Hrs
10 Days
50 Days
50 Days
17 Days
10 Days
Max Travel Distance, m
Max Decomp, GW Flow @ 0.5 m/day
1.2
NA - Solid
125
125
42.5
NA - Depends on gas Flow
Stability,
% Loss/day
10 - 95+
1-5
0.1 - 1.0
0.1 - 1.0
1-3
1-5
Speed of
Reaction
6-12 Hrs
2 - 7 Days
1 - 3 Days
1 - 3 Days
2 - 7 Days
1 - 2 Hours
T 1/2 @ Min
Decomp
5 Days
50 Days
500 Days
500 Days
50 Days
50 Days
Max Travel Distance, m
Min Decomp, GW Flow @ 0.5 m/day
12.5
NA - Solid
1250
1250
125
NA - Depends on gas Flow
Permanganate is the most stable oxidant
Promoting Readiness through Environmental Stewardship
Stewardship
22
Design Approach
Word Slide Sample (36pt)
Select an oxidant
Reactivity
Cost
Speed
Select application method
Circulation
Emplacement
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23
Oxidant Selection – Cost
Word Slide Sample (36pt)
Choose
Different
Technology
Note: If oxidant is non-reactive
go to next oxidant
No
Select
Oxidant
Soil
Samples
Is
Conduct
Contaminant Unknown
Oxidant
Oxidizable
Screening
?
Is
Peroxide
Stable
?
Screen
Peroxide
No
Yes
Yes
Screen
Ozone
Can
Ozone be
Managed
?
Continue
Design
Process
Screen
Permanganate
Is SOD
Too High
?
No
Continue
Design
Process
Yes
Screen
Persulfate
Is
Persulfate
Stable
?
Choose
Different
Technology
Yes
No
Promoting Readiness through Environmental Stewardship
Stewardship
24
Oxidant Selection – Speed
Word Slide Sample (36pt)
Choose
Different
Technology
Note: If oxidant is non-reactive
go to next oxidant
No
Select
Oxidant
Soil
Samples
Is
Conduct
Contaminant Unknown
Oxidant
Oxidizable
Screening
?
Screen
Permanganate
Is SOD
Too High
?
No
Yes
Yes
Screen
Peroxide
Speed is a function of
Reactivity
Mass delivery
Is
Peroxide
Stable
?
Continue
Design
Process
Screen
Persulfate
Is
Persulfate
Stable
?
No
Continue
Design
Process
Yes
Screen
Ozone
Can
Ozone be
Managed
?
Choose
Different
Technology
No
Yes
Promoting Readiness through Environmental Stewardship
Stewardship
25
Application Method Selection
Word Slide Sample (36pt)
Select
Oxidant
Determine
T1/2
T1/2 >
Yes
2x Reaction
?
No
T1/2 >
10m travel
?
No
Yes
Long
Treatment
Time OK
?
Yes
Select
Circulation
Method
No
Select
Emplacement
Method
Promoting Readiness through Environmental Stewardship
26
Selecting an Emplacement Method
Word Slide Sample (36pt)
Site
Conditions
Determine
Contaminant
Distribution
Is
Contaminant
<2 m?
Yes
Choose
Soil Mixing
Method
No
Are
No
Existing Wells
OK?
Is
Contaminant
>30 m?
Yes
Design
Injection
Program
Yes
Design
Fracturing
Injection
Program
No
No
Design
Geoprobe
Injection
Program
Tight or
Layered
Soils?
Yes
Design
Fracturing
Injection
Program
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27
Overview of ISCO
Word Slide Sample (36pt)
ISCO Costs
Permiting
Application
Management
Chemicals
Analytical
ISCO Success
Permiting
Application
Management
Chemicals
Analytical
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28
ISCO Summary
Word Slide Sample (36pt)
�
�
�
Many oxidants are available
A wide range of contaminants are treatable
Selecting the right oxidant is important
Reactivity
Cost
Competing reactions
�
Good design ensures success
Choose the best application method
�
�
Push Tools are an important application method
There is still room for development
Promoting Readiness through Environmental Stewardship
Stewardship
29