1. Integrated Electrodialysis
Membrane Stability Results for
Cost-Effective CBM Produced
Water Demineralization
Paula Moon and Seth Snyder
Argonne National Laboratory
Thomas Hayes, Gas Technology Institute
Presentation at the 13th International
Petroleum Environmental Conference
Oct 17-20, 2006

2. 2
Overall Objective
Develop Electrodialysis for a cost-effective and reliable
demineralization of produced waters for beneficial use purposes.
Beneficial Use Examples:
Irrigation
Livestock
Groundwater Aquifer Recharge
Habitat Maintenance/Surface Discharge

3. 3
Laboratory Evaluation Phase
1. Pretreatment to Remove Membrane Fouling factors (e.g. suspended
solids)
2. Compare CBM Produced Water Electrodialysis Process Performance
Using Selective (CMX-S) and non Selective (CMX) Cation Membranes to
Minimize Fouling Factors
3. Evaluate Electrodialysis Membranes Back Diffusion Effect of a Dilute
CBM Produced Water Feed and a large Salt Solution Concentration
4. Post Demineralization Treatment to adjust the Sodium Adsorption Ratio
(SAR) to Levels Suited to Beneficial Use
5. Perform Long Term Membrane Stability Test with non Selective
Membranes and a large Sodium Bicarbonate Solution in the Concentrate

4. 4
Electrodialysis Technology
Feed

5. 5
Schematic of Electrodialysis Stack

6. 6
Performance Characteristics of ED
Strengths
Applicable to low to moderate
TDS
Energy costs excessive at
TDS above 20,000 mg/l
Does not remove BTEX or
PAH’s like naphthalene
High water recoveries
> 92%
Low pressure operation
< 25 psi
Reduced precipitate
formation in process
Resistant to fouling
– ED Reversal (EDR)
– CIP approaches
Also removes volatile acids
Limitations

7. 7
ED Experiments Conducted
Wyoming CBM Produced Water
– Constant Current Density and non selective cation
(CMX) membranes
– Constant Current Density and selective cation
(CMX-S) membranes
– Constant Current Density, non selective cation
membrane and concentrate with a high salt
concentration of approximate 300 g/L sodium chloride
– Constant Current Density, non selective cation
membrane and 50 g/L sodium bicarbonate

8. 8
Process Flow Diagram- Produced Water Lab-Scale ED System

9. 9
Produced Water Laboratory Scale Electrodialysis System
ED Membrane

10. 10
Key Conditions for ED Lab Pilot in This Effort
Stack:
10 cell pairs
Membranes:
AMX/CMX and AMX/CMX-S
ED Unit:
Batch configuration
Constant Current
Average Voltage Drop per cell <1.5 volts

11. 11
Wyoming CBM Produced Water Concentration
CBM Produced Water Conditions
pH = 8.4
Conductivity = 1783 uS/cm
Volume = 10 L
Concentrate Solutions
5 g/L, 300 g/L sodium chloride and 50 g/L sodium
bicarbonate
Parameter Units Influent
Sodium mg/L 670
Calcium mg/L 6.7
Magnesium mg/L 2.3
Chloride mg/L 7
Alkalinity mg/L as CaCO3 1300

12. 12
Cation Membranes Characteristics
CMX CMX-S
Non Selective Membrane
Allow transport of monovalent and
divalent cations
Good Mechanical Strength Good Mechanical Strength
$500/m2 for laboratory scale $500/m2 for laboratory scale
2 yrs membrane lifetime
Selective Membrane (monoselective)
Reject >90% Calcium
Reject >90% Magnesium
2 yrs membrane lifetime

13. 13
Variation of pH and Effuent Conductivity with non
Selective CMX Cation Membranes
0
500
1000
1500
2000
2500
3000
3500
0 10 20 30 40 50 60 70
Time (min)
Conductivity(us/cm)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
pH
Conductivity
pH
CD = 4 mAmps/cm2

14. 14
Wyoming CBM Produced Water Divalent Ion
Concentration Changes and % Desalting with non
Selective CMX Membranes
0
1
2
3
4
5
6
7
IonConcentration,mg/L
0 52 57 65
Time, min
Calcium
Magnesium
CD = 4 mAmps/cm2
92% 92% 87%87% 87%
87%

15. 15
Variation of pH and Effluent Conductivity with Selective
CMX-S Cation Membranes
0
500
1000
1500
2000
2500
3000
0 10 20 30 40 50 60
Time (min)
Conductivity(us/cm)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
pH
Conductivity CMX-S
pH CMX-S
CD = 4 mAmps/cm2

16. 16
Wyoming CBM Produced Water Divalent Ion
Concentration Changes and % Desalting with Selective
CMX-S Membranes
CD = 4 mAmps/cm2
0
1
2
3
4
5
6
7
IonConcentration,mg/L
0 40 50 55
Time, sec
Calcium
Magnesium37%
22%
52%
72%
63%
62%

17. 17
Power Consumption as a function of % Desalting, Cation
Membrane Type and SAR
0.00
0.05
0.10
0.15
0.20
0.25
PowerConsumption,kWhr/lbNaClequiv.
AMX/CMX, 95% AMX/CMX, 96% AMX/CMX-S, 88% AMX/CMX-S, 92%
SAR
10.2
SAR
9.3
SAR
10.9
SAR
8.3
CD= 4 mAmps/cm2

18. 18
Effect of Amount of Sodium in the Soil
USDA Agriculture Handbook # 60, Diagnosis and
Improvement of Saline and Alkali Soils, page 80, 1954
Irrigation water with excess amount of sodium can adversely impact soil structure
and plant growth.

19. 19
Wyoming CBM Produced Water with AMX/CMX-S
Membranes at CD = 4 mAmps/cm2 and Post Demineralization
Treatment
Parameter Units Influent Effluent Adjusted SAR Adjusted SAR Adjusted SAR
w/limestone w/CaCO3
w/CaSO4
Sodium mg/L 670 56 55 56 57
Calcium mg/L 6.7 1.9 18 17 690
Magnesium mg/L 2.3 0.9 1.6 2.7 1.0
Alkalinity mg/L CaCO3
1300 350 180 210 140
Chloride mg/L 140 7 11 13 11
Conductivity us/cm 2650 331 333 324 2820
SAR 56.2 8.3 3.3 3.3 0.6
pH 8.3 7.0 8.3 8.3 7.9
Level Suited to Beneficial Use

20. 20
Back Diffusion observed at the beginning of the ED run
with a salt concentration greater than 300 g/L NaCl
0
500
1000
1500
2000
2500
3000
0 20 40 60 80 100 120 140 160 180
Time (min)
EffluentConductivity(us/cm)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
pH
Conductivity
pH
AMX/CMX membranes and CD= 4 mAmps/cm2
0.53 kWh/lb NaCl equiv.
and 92 % desalting

21. 21
Wyoming CBM Produced Water Concentration
CBM Produced Water Conditions
pH = 8.6
Conductivity = 2780 uS/cm
Volume = 10 L
Concentrate Solution
50 g/L sodium bicarbonate
Parameter Units Influent
Sodium mg/L 840
Calcium mg/L 6.7
Magnesium mg/L 2.7
Chloride mg/L 39
Alkalinity mg/L as CaCO3 1400

22. 22
Effuent Conductivity and Cell Voltage Profiles for Long
Term Membrane Stability Test
with AMX/CMX Membranes and CD= 3 mAmps/cm2
0
500
1000
1500
2000
2500
3000
3500
0 2 4 6 8 10 12 14 16 18 20
Time ( hr)
EffluentConductivity(us/cm)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
CellVoltage(volts)
Conductivity
Cell Voltage

23. 23
Effluent and Concentrate pH Profiles for Long Term
Membrane Stability Test with AMX/CMX membranes and
CD= 3 mAmps/cm2
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
0 2 4 6 8 10 12 14 16 18 20
Time (hr)
pH
Effluent pH
Concentrate pH

24. 24
Concentrate Solution @ 20 hrs of Membrane Stability
Test with AMX/CMX Membranes
Parameter Units Concentrate
Sodium mg/L 16000
Calcium mg/L 14
Magnesium mg/L 49
Chloride mg/L 440
Alkalinity mg/L as CaCO3 36000

25. 25
Conclusions
Produced water recovery efficiency >90 %
Modest energy input: 0.14 – 0.20 kWh/lb NaCl equiv. removed
Achieves 92% removal of dissolved solids
New selective membrane CMX-S reduces scaling potential
Back diffusion observed for concentrate solutions greater than 300
g/L NaCl
Non selective membrane with a sodium bicarbonate solution in the
concentrate perform well in long term membrane test

26. 26
Acknowledgments
This Work was Supported with Funding from
DOE/NETL-NPTO
Thanks to Brian A. Hodgson
from Marathon Oil Company for supplying the CBM
Produced Water to run these experiments