Silvia Jimenez Herrera, ingeniera de I+D en ACCIONA Agua, presenta la ponencia “Novel Process for Produced Water Polishing: Enhanced Flotation Combined With Advanced Oxidation Processes’ durante la conferencia anual que la asociación europea de desalación ha celebrado en Roma entre los días 22-26 de mayo de 2016.

1. © 2016 Acciona Agua S.A.U. All rights reserved.
Novel Process for Produced Water Polishing: Enhanced
Flotation Combined With Advanced Oxidation Processes
S. Jiménez, M. Arnaldos, C. Bayona, M. M. Micó, E. Ferrero, J. Malfeito, S.
Contreras
23/05/2016, Rome

2. INDEX
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3. 1. INTRODUCTION
1.1. ORIGIN OF PRODUCED WATER
PW:
Formation water (trapped underground) under HC that comes to the surface
when oil and gas are extracted
+
Injection water (oil and gas extraction causes a reduction of the P in the
reservoir and water is injected to maintain hydraulic P and improve the
recovery of oil).
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4. 1. INTRODUCTION
1.2. CONVENTIONAL TREATMENT TRAIN OF PRODUCTION FLUIDS
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~ 550 ppm O&G
15-100 ppm O&G
• Limits Legislation for
discharge (PW from
offshore operation)
~ 30-40 ppm O&G
• Reutilization of PW
Advanced water
treatment
technologies
(Polishing)

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5. 1. INTRODUCTION
1.3. POLISHING TECHNOLOGIES
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 Enhanced flotation using glass microspheres (EFM)
 EFM combined with conventional DAF (Dissolved Air Flotation)
COAGULATION-FLOCCULATION stage (FeCl3) flocs separated from the aqueous phase
by the above treatments.
Next step: To polish even further O&G content of the effluent and to take advantage of
residual iron after these treatments AOPs

6. 2. MATERIALS AND METHODS
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2.1. COMPOSITION OF SYNTHETIC PRODUCED WATER EMULSION IN A
SEAWATER MATRIX
(Filtered seawater + 100 mg/L of gasoline lubricant + 50 mg/L of olive oil (~150 ppm of O&G) + 5
ppm phenol + 15 µL of Triton-X-100 surfactant as an emulsifier. This mixture was stirred at 1600
rpm for 10 min).
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Water Quality Parameter Value
COD (mg/L) 342,5
Turbidity (NTU) 120
Phenols (mg/L) 5
O&G (mg/L) 167,8

7. 2. MATERIALS AND METHODS
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2.2. ENHANCED FLOTATION USING MICROSPHERES (EFM) AND EFM COMBINED
WITH CONVENTIONAL DAF
(DAF Jar Tester)
COAGULATION-FLOCCULATION: 2 min at 200 rpm + 15 min at 90 rpm or 40 rpm
[FeCl3]: 0-58 ppm;
[Microspheres]: 50-300 ppm;
pH: free pH
EFM-DAF:
P air injection: 6 bar
Recycle rate: 15 %
Flotation time: 2 min
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8. 3. RESULTS
3.1. ENHANCED FLOTATION USING GLASS MICROSPHERES
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Standardized Pareto Chart for Turbidity removal, %
0 1 2 3 4 5
Standardized effect
AC
A:[Microspheres]
C:Flocculation rate
AB
+
-
86,2% of turbidity removal using 300 ppm microspheres, 20 ppm Fe
(FeCl3) and flocculation rate of 40 rpm (without air injection).
A: Microspheres
concentration.
B: Fe concentration.
C: Flocculation rate.

9. 3. RESULTS
3.2. ENHANCED FLOTATION USING GLASS MICROSPHERES COMBINED WITH
CONVENTIONAL DAF
P air injection: 6 bar
Recycle rate: 15 %
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Standardized Pareto Chart for Turbidity removal, %
0 0,4 0,8 1,2 1,6 2 2,4
Standardized effect
AC
BC
C:Flocculation rate
AA
A:[Microspheres]
B:[Fe]
AB +
-
Turbidity removal is lower (maximum 69%) than using microspheres without
microbubbles (86,2%) because air injection destabilizes formed flocs.

10. 3. RESULTS
3.3. O&G REMOVAL
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• The turbidity of PW was correlated to its O&G concentration:
Max turbidity removal, % Max O&G removal, %
Microspheres 86 94
Microspheres+DAF 69 75
 Enhanced flotation using microspheres is suitable for O&G removal (with the advantage of
reducing energy consumption required in the DAF), but soluble organic compounds as phenol
are not eliminated AOP
Microspheres Microspheres & Microspheres+DAF
Final O&G content 10
ppm (<30 ppm
legislation).
Phenol is not removed

11. 4. AOPS
4.1. FENTON
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 Using H2O2 and Fe2+ (FeSO4·7H2O) at pH 3 and magnetic stirring

12. 4. AOPS
4.1. FENTON
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Time reaction: 6 hours:
[H2O2]: 283-2660 ppm; (H2O2/COD (w): 2,1-20)
[Fe2+]: 28,3-5320 ppm
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Max 48 %
of O&G
removal
• Synthetic PW:
Water Quality Parameter Concentration
COD (mg/L) 160
Phenols (mg/L) 5
O&G (mg/L) 40

13. 4. AOPS
4.1. FENTON
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Time reaction: 24 hours:
[H2O2]: 283-1409 ppm;
(H2O2/COD (w): 2,1-10,6)
[Fe2+]: 5,65-704 ppm
70% phenol removal (50% in
the first 2 min)
70% phenol removal (50%
Max 55 % of O&G
removal

14. 4. AOPS
4.2. PHOTO-FENTON
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 Solarbox with a 2500 W Xenon lamp and an outdoor light filter (allowing 290-800
nm wavelength to pass through) to simulate solar radiation. Irradiance: 250 W·m-2
Time reaction: 3 hours:
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 H2O2 was consumed after 3 hours of reaction
 Similar O&G removal to the Fenton process with lower reagents
doses
 92% of phenol removal

15. 5. CONCLUSIONS
 Flotation process based on the use of glass microspheres (EFM) is suitable for
turbidity and O&G removals in PW but not for soluble compounds elimination, as
phenol:
 EFM removed turbidity of PW to levels higher than 85%, with a coagulation step of 2
minutes at 200 rpm, followed by an optimal flocculation rate of 40 rpm during 15
minutes with an iron dose of 20 mg/L and microspheres concentration of 300 mg/L.
 The turbidity of PW was correlated to its O&G concentration, and up to 90 % of O&G
removal was achieved, (resulting a concentration lower than the effluent
requirements).
 Air injection (which also implies energy consumption) is not suitable because
microbubbles cause floc breakup.
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16. 5. CONCLUSIONS
 In order to remove the phenol and to take advantage of residual iron, Fenton and
photo-Fenton reactions were essayed:
Phenol is eliminated but O&G content is difficult to remove due to the high amount
of salts containing this water (some ions, such as chlorides, reduce the efficiency in
oxidation systems employing oxidizing agent such as hydroxyl radicals) and because
of the heterogeneous mixture of this PW that can prevent Fenton reagents do not
mix well:
 Fenton reaction did not show substantial degradation of O&G with different dose of
reagents and reaction times (a maximum removal of 48 %) although phenol was
eliminated in a 70 % in the first minutes of reaction.
 Photo Fenton process during 3 hours, showed similar removal of O&G but phenol was
almost completely eliminated.
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17. © 2016 Acciona Agua S.A.U. All rights reserved.
Thank you for your attention
ACKNOWLEDGEMENTS
The presented research has been carried out in the framework of an Industrial Doctorate Programme (2013 DI 037)
with the support of the ‘Secretaria d’ Universitats i Recerca del Departament d’Economia i Coneixement de la
Generalitat de Catalunya’