This document summarizes research on treating flowback and produced water from hydraulic fracturing operations. It finds that electrocoagulation and chemical coagulation can effectively remove various contaminants from the water, including metals, calcium, barium, and turbidity. Electrocoagulation achieved similar or better removal rates than chemical coagulation and was most effective when used after softening the water through pH adjustment. Treating younger flowback water (within 1 hour) was also more effective than treating older flowback water. Future work should examine how treatability changes over time and evaluate additional treatment methods and chemical parameters.

1. Water Quality and Treatment of Frac Flowback and Produced Water
Nasim Esmaeilirad
Ryan Hutcherson
Colorado State University
August 12, 2013

2. Overview on produced water
• Oil and gas within underground in source rock referred as Formations.
• Geology of formations vary along with hydrocarbons characteristics.
• Different methods are used for different formations.
• While some oil and gas are produced by drilling a well and relying on the natural pressure to
come out to the surface, hydraulic fracking is used to extract some hydrocarbons .
• Hydraulic fracking: Injection of water along with chemicals and sand under high pressure
inside the ground.
• Produced water is a key byproduct comes out to the surface along with oil and gas.
• 250mbbr of produced water was generated per day in the world in 2009, corresponding to
80mbbrs of produced oil.
• 21mbbrs of PW was generated in the USA.
• About 90% of produced water is injected to the deep wells.
• Given this huge amount of produced water and growing demand of fresh water give a potential
source of water in replace of conventional source of water

3. Basic Water Use Model
Groundwater
Municipal Water
Surface Water
Drilling and
Hydraulic Fracturing
Flowback and
Produced Water
Deep Injection Well

4. Water Reuse Model
Groundwater
Municipal Water
Surface Water
Drilling and
Hydraulic Fracturing
Flowback and
Produced Water
Deep Injection Well
Treatment
Dilution

6. 0
50
100
150
200
250
0 20 40 60 80 100
Iron(mg/L)
Days
Frac Fluid ll Frac Fluid ll
0
50
100
0 2 4 6 8 10 12
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 20 40 60 80 100
Aluminum(mg/L)
Days
Frac Fluid ll Frac Fluid ll
0
2
4
6
0 2 4 6 8 10 12
Raw Water Quality

7. Raw Water Quality
0
50
100
150
200
250
300
350
400
0 20 40 60 80 100
Calcium(mg/L)
Frac Fluid l Frac Fluids ll
0
100
200
0 2 4 6 8 10 12
0
5
10
15
20
25
30
35
0 20 40 60 80 100
Barium(mg/L)
Days
Frac Fluid l Frac Fluid ll
0
2
4
6
0 2 4 6 8 10 12

8. Raw Water Quality
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
0 20 40 60 80 100
Chloride(mg/L)
Days
Frac Fluid l Frac Fluid ll
0
5000
10000
0 2 4 6 8 10 12
0
200
400
600
800
1000
1200
1400
0 20 40 60 80 100
Sulfate(mg/L)
Days
Frac Fluid l Frac Fluid ll
0
500
1000
1500
0 2 4 6 8 10 12

9. Raw Water Quality
1000
2000
3000
4000
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
TOC(mg/L)
Frac Fluid l Frac Fluid ll
0
5000
10000
15000
20000
25000
30000
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
TDS(mg/L)
Days
Frac Fluid l Frac Fluid ll
400
900
1400
1900
2400
2900
3400
3900
0 1 2 3 4

10. Raw Water Quality
0
1
2
3
4
5
6
7
8
9
0 20 40 60 80 100
pH
Frac Fluid ll Frac Fluid l

11. (1) Electrocoagulation => Softening => Solid-Liquid Separation
(2) Softening => Electrocoagulation => Solid-Liquid Separation
(3) Chemical coagulation => Softening => Solid-Liquid separation
Chemical and Electro Coagulation (EC) Processes Studied
Goals:
• Determine the point in time when flowback can be treated
effectively
• Determine what type of treatment and dosage is most effective on
early flowback
• Determine which water quality parameters could be used as
indicators of whether treatment will be successful

12. Chemical Coagulation
• Destabilize (charge neutralize) solid particles using tri-valent cations
• A blend of Aluminum and a polymer were used
• HCl was used to lower the raw water pH to 6 (increase hydration of floc blend)
• Each raw sample was treated with a dosage of 5 parts per thousand of Floc
Blend and stirred for approximately 2 minutes
• Floc Blend consists of a 1:1 ratio of Aluminum Chlorohydrate (ACH) and Poly-
aluminum Chloride (PACl)
• Aluminum dosage was approximately 449 mg/L
• Floc was allowed to settle for approximately 20 minutes
• Once settled water was decanted off the top softened at a pH of 10.2 (NaOH)
2.5μm glass fiber filters either with positive pressure or a vacuum were used
• HCl was then used to lower pH to neutral (~ 7)

13. Electrocoagulation
Insitu generating coagulants:
• Using electricity to dissolution and oxidation of
metal ions in anode: Aluminum or/and Iron plates/disc.
• Formation of hydroxyl ions(Aluminum hydroxide) and
hydrogen gas at the cathode.
• Reacting with the hydroxyl ion (from the cathode) to
form Aluminum hydroxide.
• The hydroxide flocculates and coagulates purifying
the water.

14. EC/Softening (1) and Softening/EC (3) Schematics
Raw
water
EC
pH = 10.2
(NaOH)
pH = 7
(HCl)(1)
(2)
2.5 m
filter
Sample A
2.5 m
filter
Sample B
2.5 m
filter
DissolvedTotal
2.5 m
filter
2.5 m
filter
pH = 7
(HCl)
pH = 9.5
(NaOH)
Sample A Sample B Sample C
EC

15. EC (1) and Chemical Coagulation (2) Schematics
Raw
water
EC
pH = 10.2
(NaOH)
pH = 7
(HCl)(1)
(3)
2.5 m
filter
Sample A
2.5 m
filter
Sample B
Sample A Sample B Sample C
2.5 m
filter
DissolvedTotal
Chemical
Treatment
pH = 10.2
(NaOH)
2.5 m
filter
2.5 m
filter
pH = 7
(HCl)

16. Treated Water Quality (EC vs. CC)
50
55
60
65
70
75
80
85
90
95
100
0
50
100
150
200
250
300
350
400
450
500
1 2 26.5 69.5 90 153 161 183 1 2 70
%
Aluminum(mg/L)
Raw
Post-EC
Post-CC
% Removal-EC
% Removal-CC
Frac Fluid l (guar based, pH=10.2) Frac Fluid ll (non-guar, pH=5)
0
10
20
30
40
50
60
70
80
90
100
0
50
100
150
200
250
1 2 26.5 69.5 90 153 161 183 1 2 70
%
Iron(mg/L)
Raw
Post-EC
Post-CC
% Removal-EC
Series5

17. Treated Water Quality (EC vs. CC)
0
10
20
30
40
50
60
70
80
90
0
50
100
150
200
250
300
350
400
450
1 2 26.5 69.5 90 153 161 183 1 2 70
%
Calcium(mg/L)
Raw
Post-EC
Post-CC
% Removal-EC
% Removal-CC
0
10
20
30
40
50
60
70
80
90
100
0
5
10
15
20
25
30
35
1 2 26.5 69.5 90 153 161 183 1 2 70
%
Barium(mg/L)
Raw
Post-EC
Post-CC
% Removal-EC
% Removal-CC
Frac Fluid l (guar based, pH=10.2) Frac Fluid ll (non-guar, pH=5)

18. Treated Water Quality (EC vs. CC)
0
20
40
60
80
100
120
0
500
1000
1500
2000
2500
1 2 26.5 69.5 90 153 161 183 1 2 70
%
COD(mg/L)
Raw
Post-EC
Post-CC
% Removal-EC
% Removal-CC
0
20
40
60
80
100
120
0
500
1000
1500
2000
2500
1 2 26.5 69.5 90 153 161 183 1 2 70
%
TOC(mg/L)
Raw
Post-EC
Post-CC
% Removal-EC
% Removal-CC
Frac Fluid l (guar based, pH=10.2) Frac Fluid ll (non-guar, pH=5)

19. 0
20
40
60
80
100
120
0
500
1000
1500
2000
2500
3000
3500
4000
4500
1 2 26.5 69.5 90 153 161 183 1 2 70
%
Turbidity(NTU)
Raw
Post-EC
Post-CC
% Removal-EC
% Removal-CC
Treated Water Quality (EC vs. CC)
Frac Fluid l (guar based, pH=10.2) Frac Fluid ll (non-guar, pH=5)

20. Treated Water Quality (softening before/after EC)
-61.71
-38.43
-46.15
87.62
95.06 99.68 99.76 99.82 98.85 99.72 98.56
-150.00
-100.00
-50.00
0.00
50.00
100.00
150.00
0.00
500.00
1000.00
1500.00
2000.00
2500.00
3000.00
3500.00
4000.00
4500.00
1 1 2 2 30 60 60 90 153 161 183
Removal%
Turbidity(NTU)
Days
Turbidity
Raw EC
pH EC removal
pH removal

21. -500.00
0.00
500.00
1000.00
1500.00
2000.00
2500.00
3000.00
3500.00
4000.00
4500.00
0.00
500.00
1000.00
1500.00
2000.00
2500.00
3000.00
1 1 2 2 30 60 60 90 153 161 183
Turbidity(NTU)
TOC(mg/l)
Days
TOC Vs Turbidity
TOC TOC-EC TOC-pH Turbidity Turbidity-EC Turbidity-pH
Treated Water Quality (softening before/after EC)

22. 0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
450.00
1 1 2 2 30 60 60 90 153 161 183
Concentration(mg/)
Days
Hardness
Raw-Ca+2 EC-Ca+2 pH-Ca+2 Raw-Mg+2 EC-MG+2 pH-Mg+2
Treated Water Quality (softening before/after EC)

23. 0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
0.00
20.00
40.00
60.00
80.00
100.00
120.00
140.00
160.00
180.00
200.00
1 1 2 2 30 60 60 90 153 161 183
Al+3(mg/l)
Fe+2(mg/l)
Days
Al vs Fe
Fe+2 EC-Fe+2 pH-Fe+2
Al+3 EC-Al+3 pH-Al+3
Treated Water Quality (softening before/after EC)

24. Treatment Comparison after 1 hour
Treated Water Quality (softening before/after EC)

25. Comparison between EC Only and Increased pH before EC
Treated Water Quality (softening before/after EC)

26. Future Work
• Collect water samples for chemical treatability study
• 5 days, 10 days, 20 days
• Frac Fluid l and Frac Fluid ll
• Use same chemical treatment process
• Repeat flowback study
• Time intervals to be determined
• Treat samples with various coagulants and processes (i.e. Alum, Ferric
Chloride, 2 stage treatment)
• Measure change in dose-repose over the first month to better understand
treatability changes with time.
• Additional Analytical Parameters
• Detailed characterization of organics
• Seek a more simple measure of the class of organics which are found to be
most important (from a treatment point of view)