The Effect of Pretreatment to Seawater Reverse Osmosis SWRO: A Detailed Molecular Weight Distributio

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The Effect of Pretreatment to Seawater Reverse
Osmosis (SWRO) A Detailed Molecular Weight
Distribution (MWD)

• H. K. Shon
• Faculty of Engineering, University of Technology,
  Sydney, P.O. Box 123, Broadway, NSW 2007,
  Australia

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INTRODUCTION
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History of Water Resources
1st generation
2nd
3rd
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• John F. Kennedy said If we could produce fresh
  water from salt water at a low cost, that would
  indeed be a service to humanity, and would dwarf
  any other scientific accomplishment (1962)

• Barry Nelson said Ten years ago, desalination
  was the crazy aunt in the attic. Thats changed.
  It is now entering the mainstream and being taken
  seriously (2003)

Adapted from MEDINA, 2006
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Importance of SWRO

• Effective in treating water of any salinity

• The cost is getting cheaper (0.5/m3)

• Simple operation

• High reliability

• Large flexibility

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RO Membrane

• Membranes composite - Cellulose acetate
  membrane - Composite polyamide membrane

• Driving force pressure (60 70 bar)

• Both size exclusion and charge effect
  (solution-diffusion)

• Sublayer 150 µm and toplayer 1 µm

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Fouling Mechanism of RO

• Use of RO alone severe fouling

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asd
Types of Membrane Foulant in SWRO
Khedr et al., 2000
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Foulant Types
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Strategies of Fouling Reduction
Retentate
Feed
Pretreatment
Membrane
Permeate
Mulder, 1996
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Pretreatment of SWRO

• Conventional pretreatment

RO
Permeate tank
Feed tank
Flocculation

• Advanced pretreatment

Feed tank
RO
Permeate tank
MF/UF/NF
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Approaches of Foulant Characteristics
DOC removal and flux decline
Retentate
Feed
Membrane
Pretreatment
Membrane characterization
Permeate
MWD
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Objective
Huber, 1998
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Objectives

• Effect of seawater organic matter (SWOM) on the
  RO membrane with and without pretreatment

• A detailed characterization of SWOM foulants
  with/without pretreatment in terms of MWD

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Experimental
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Seawater
N35º456, E126º2626 almap program
used Map adapted from lonelyplanet
www.lonelyplanet.com)
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Characteristics of Hampyeong Seawater
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Characterization of Activated Carbon
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MF (0.45 µm), UF (10000 Da) and NF (1000 Da)
Pretreatment

• Pressure 4.5 bar Temp. 20 ºC
  Effective surface area 41.8 cm2

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Crossflow NF unit
1. Effective membrane area 0.006 m22. Pressure
60 bar3. Cross-flow velocity 0.5 m/s4.
Laminar flow
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Characteristics of Membranes used
MWCO molecular weight cut off PWP pure
water permeability
Lee et al., 2000
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Molecular Weight Distribution
UVA
Eluent
HPLC
Computer
Molecular weight (MW) distribution was measured
using high performance size exclusion
chromatography (HPSEC) using a SEC column
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Results and Discussion
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SWOM Characteristics
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SWOM Removal by Different Pretreatments
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Hydrophilic, Transphilic and Hydrophobic
Concentration by Different Pretreatments
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MWD with Different Water Sources
Drinking water
General component
Wastewater
Seawater
www.doc-labor.de
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MWD with Different Pretreatments of Loose NF
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ne
MWD with Different Fractions
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MWD after Flocculation and Adsorption
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MWD after UF and NF
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Pretreatment to SWRO
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Flux Variation of SWRO
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SWOM Variations of SWRO Concentrate with Time
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MWD of the RO Permeate
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MWD of SWRO Concentrates after MF Pretreatment
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MWD of SWRO Concentrates after PAC Pretreatment
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MWD of SWRO Concentrates after UF Pretreatment
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MWD of SWRO Concentrates after FeCl3 Pretreatment
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Conclusions
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Acknowledgements

• Many thanks to Prof. J. Cho, Prof. In S. Kim and
  Dr. S. Kim for facilitating my stay and giving me
  a special care

• Many thanks to E.K. Lee for measuring inorganic
  compounds

• Many thanks to G.M. Chon and S.J. Kim for
  sharing talks and food

• Many thanks to N.E. Park, Sarp and Hanh for
  enjoying daily life during my stay