Reclamation of Oilfield Produced Water using a Hydrophilic Pervaporative Membrane

May Sule (PhD Candidate)*, Dr Michael R. Templeton (Supervisor)

Department of Civil and Environmental Engineering, Imperial College London

m.sule08@imperial.ac.uk

Project Aims

• Experimentally evaluate and model the removal of salts, petroleum hydrocarbon compounds (benzene, toluene, xylene, ethylbenzene) and arsenic from water by a pervaporative hydrophilic membrane.

• Assess the practicability of using the pervaporative membrane for treating oilfield produced water and possibly as an irrigation pipe technology for use in water-scarce regions.

Why oilfield produced water?

Oilfield produced water is by far the largest waste stream in the oil and gas industry worldwide

Composition:• Salts (sodium chloride ≈ 80%, i.e. 70-300 g/l), • Dissolved or suspended hydrocarbons, VOCs (aromatic hydrocarbons of BTEX 0.068-578 mg/l)• Total dissolved solids TDS (100mg/l -300,000 mg/l)• Heavy metals (Arsenic etc) • Cations (sodium, calcium, magnesium, potassium)• Anions (chloride, sulphate, bicarbonate)

http://www.amcol.com/http://www.jccp.or.jp/english/ ;

Current treatment methodsCurrent treatment methods:

• Physical, chemical ,biological, reinjection*

Disadvantages of current treatments:

• Mechanical parts

• High energy requirements

• High cost of chemicals

• High operational & maintenance costs

• Managing chemical residuals

• Tackling high TDS concentrations

• Environmental implications

• Injectivity decline

http://www.unep.org/conflictsanddisasters/ ; www.veoliawaterst.com

What is Pervaporation?

Membrane

Evaporation

Permeate

vapour

Feed

liquid

Dissolution

δ

Diffusion

Pervaporation theory

1. Property of polymer materialAvailability of holes in the polymer is an intrinsic property of the polymer material and depend on

• Polymer structure• Crosslink density • Morphology

Polymer property determines permeability and selectivity of membrane material

2. Transport mechanisms in polymersJump event and concept of free volumeMolecular dynamics simulationsHopping motionPenetrants in cavities

Ref: Mullerplathe, 1994

Schematic representation of penetration of solvent molecules in the polymer matrix

Pervaporation theory

Physical properties of solvents at 25oC

Material Molecular weight (g/mol)

Solubility in water(mg/L)

Molar volume (cm3/G.Mole)

Water BenzeneTolueneEthylbenzeneo-Xylenem-Xylenep-Xylene1,1,1-Trichloroethane1,1,2-TrichloroethaneTrichloroethylene

1878.1192.13106.17106.17106.17106.17133133132

1,7805151521751961901,3201,3181,100

1889.11106.847123.064121.193123.456123.91999.292.490.4

Ref: Haxo and Lahey, 1988, Peng et al., 2003, Islam and Rowe, 2009

H-bonding, polar and dispersion coefficients

Comparison of polar and dispersion contribution of solvents

Grouped organics in terms of the two-dimensional solubility parameter

Ref: Shao and Huang, 2007

Hansen solubility parameters HSP δ2 = (δD)2 + (δP)2 + (δH)2

Current study

Pipes are made with a unique hydrophilic DuPont polymer that allows water vapour—which cannot carry salts—to diffuse through the pipe walls, while the contaminants are retained within the pipes.Trials by DTI - allow plant growth with similar salted/brackish water.Highly effective, no chemical use, no energy required, environmentally friendly, simple in design, operationally convenient.

Illustration : Lindsay Todman

Methodology

immersion/sorption tests (bottle tests)

permeation/diffusion tests

Initial Results

Sorption curve for polymer membrane immersed in deionised water indicating Fickian pattern

Ave water uptake=4.51 x 10-4 m3/m2/d

Diffusion coefficient = 3.3 x 10-3 m2/d

=

Initial Results

Volume sorbed using NaCl

Volume sorbed using humic acid solution

Volume sorbed using MgCl2

Volume sorbed using NaCl

Initial Results

Current / Future work

• Further bench-experiments based on solution-diffusion to determine transport properties on oilfield contaminants (BTEX, salts, arsenic)

• Assess the operational performance of the pipe technology for treating oilfield produced water by investigating the impact of ambient conditions (i.e. the composition/constituents, concentration, temperature, humidity, soil homogeneity) on water flux and water quality using soil columns.

• Use of scanning electron microscopy (SEM) to further determine polymer characteristics in its swelled (water-carrying) state

• Mathematical modelling to describe the mass transfer rate and relate it to the water quality parameters i.e concentrations of relevant constituents, temperature and membrane proportions for successful treatment implementation at geographically diverse field sites.

References

HAXO, H. E. & LAHEY, T. P. 1988. TRANSPORT OF DISSOLVED ORGANICS FROM DILUTE AQUEOUS-SOLUTIONS THROUGH FLEXIBLE MEMBRANE LINERS. Hazardous Waste & Hazardous Materials, 5, 275-294.

ISLAM, M. Z. & ROWE, R. K. 2009. Permeation of BTEX through Unaged and Aged HDPE Geomembranes. Journal of Geotechnical and Geoenvironmental Engineering, 135, 1130-1140

MULLERPLATHE, F. 1994. PERMEATION OF POLYMERS - A COMPUTATIONAL APPROACH. Acta Polymerica, 45, 259-293.

PENG, M., VANE, L. M. & LIU, S. X. 2003. Recent advances in VOCs removal from water by pervaporation. Journal of Hazardous Materials, 98, 69-90.

SHAO, P. & HUANG, R. Y. M. 2007. Polymeric membrane pervaporation. Journal of Membrane Science, 287, 162-179.

Websites: www.veoliawaterst.com ; http://www.jccp.or.jp/english/ ; http://www.amcol.com/OilfieldProducedWaterTreatment.aspx ; http://www.oilplus.co.uk/ ; http://www.unep.org/conflictsanddisasters/

Questions???