integrated electrodialysis membrane stability results for cost-effective cbm produced water...
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Integrated Electrodialysis Membrane Stability Results for Cost-Effective CBM Produced
Water Demineralization
Paula Moon and Seth Snyder Argonne National LaboratoryThomas Hayes, Gas Technology Institute
Presentation at the 13th International Petroleum Environmental ConferenceOct 17-20, 2006
2
Overall Objective
Develop Electrodialysis for a cost-effective and reliable demineralization of produced waters for beneficial use purposes.Beneficial Use Examples:
IrrigationLivestockGroundwater Aquifer RechargeHabitat Maintenance/Surface Discharge
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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
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Electrodialysis Technology
Feed
5
Schematic of Electrodialysis Stack
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Performance Characteristics of EDStrengths
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 psiReduced precipitate formation in processResistant to fouling– ED Reversal (EDR)– CIP approaches
Also removes volatile acids
Limitations
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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
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Process Flow Diagram- Produced Water Lab-Scale ED System
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Produced Water Laboratory Scale Electrodialysis System
ED Membrane
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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 CurrentAverage Voltage Drop per cell <1.5 volts
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Wyoming CBM Produced Water Concentration
CBM Produced Water Conditions pH = 8.4Conductivity = 1783 uS/cmVolume = 10 L
Concentrate Solutions5 g/L, 300 g/L sodium chloride and 50 g/L sodium bicarbonate
Parameter Units InfluentSodium mg/L 670Calcium mg/L 6.7Magnesium mg/L 2.3Chloride mg/L 7Alkalinity mg/L as CaCO3 1300
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Cation Membranes Characteristics
CMX CMX-SNon 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
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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)
Con
duct
ivity
(us/
cm)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
pH
ConductivitypH
CD = 4 mAmps/cm2
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Wyoming CBM Produced Water Divalent Ion Concentration Changes and % Desalting with non Selective CMX Membranes
0
1
2
3
4
5
6
7
Ion
Con
cent
ratio
n, m
g/L
0 52 57 65
Time, min
CalciumMagnesium
CD = 4 mAmps/cm2
92% 92% 87%87% 87%87%
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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)
Con
duct
ivity
(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-SpH CMX-S
CD = 4 mAmps/cm2
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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
Ion
Con
cent
ratio
n, m
g/L
0 40 50 55Time, sec
CalciumMagnesium37%
22%
52%
72%63%
62%
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Power Consumption as a function of % Desalting, Cation Membrane Type and SAR
0.00
0.05
0.10
0.15
0.20
0.25
Pow
er C
onsu
mpt
ion,
kW
hr/lb
NaC
l equ
iv.
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
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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.
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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
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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)
Effl
uent
Con
duct
ivity
(us/
cm)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
pH
ConductivitypH
AMX/CMX membranes and CD= 4 mAmps/cm2
0.53 kWh/lb NaCl equiv.and 92 % desalting
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Wyoming CBM Produced Water Concentration
CBM Produced Water ConditionspH = 8.6Conductivity = 2780 uS/cmVolume = 10 L
Concentrate Solution50 g/L sodium bicarbonate
Parameter Units InfluentSodium mg/L 840Calcium mg/L 6.7Magnesium mg/L 2.7Chloride mg/L 39Alkalinity mg/L as CaCO3 1400
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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)
Effl
uent
Con
duct
ivity
(us/
cm)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Cel
l Vol
tage
(vol
ts)
ConductivityCell Voltage
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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 20Time (hr)
pH
Effluent pHConcentrate pH
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Concentrate Solution @ 20 hrs of Membrane Stability Test with AMX/CMX Membranes
Parameter Units ConcentrateSodium mg/L 16000Calcium mg/L 14Magnesium mg/L 49Chloride mg/L 440Alkalinity mg/L as CaCO3 36000
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ConclusionsProduced 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 theconcentrate perform well in long term membrane test
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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