Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,for the United States Department of Energy’s National Nuclear Security Administration
under contract DE-AC04-94AL85000.
The Role of Chemistry and Materials Science in
Advanced Water Treatment
SAND No. 2011-5958P
Materials science is an essential part of water treatment infrastructure
IntroductionWater treatment processesMaterials science for water infrastructure
Membrane technology- polymericMicro and ultrafiltration (MF and UF)Nanofiltration and reverse osmosis (NF and RO)Recent RO membrane advances
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Materials science has a dramatic effect on water treatment infrastructure
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Glass reinforced plastics - corrosion
Pump coatings - friction reduction
Pipe lining – trenchless technology
Composite pumps – corrosion resistant
Steel alloys (Duplex SS)- corrosion resistant
Polymers, resins, additives- treatment
Polymeric membranes- porous: water purification, nonporous: desalination- pressure driven
Source : U.S. Filter
Membranes have revolutionized water treatment
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http://www.ionics.com/technologies/ro/index.htm#
http://www.gewater.com/products/equipment/mf_uf_mbr/zeeweed_500.jsp
http://www.pall.com/power_34168.asp
Membrane separation spectrum
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Dissolved salts Nonporous
BacteriaVirus
Suspended solids/ DOM Porous
Porous: Filtration by size - molecular weight cutoff (MWCO). Nonporous: Solution diffusion separation – hydrated ions.Removal: Salinity can be reduced only by RO/NF membrane treatment.
The Future of Desalination in Texas:Texas Water Development Board 2,(2004) 137-154Alyson Sagle and Benny D. Freeman,
CoagulationFlocculation
Sedimentation and or filtration
Basic water treatment removes particles and dissolved organics
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Coagulant
•Removal of particles and natural organic matter (NOM), color, disinfection byproducts (DBP), iron, manganese, arsenic, taste, odor.
•Granular activated carbon can be used as a filter and adsorber, but regeneration may be different than sand media.
Coagulation Flocculation
Microfiltration or Ultrafiltration
Microfiltration (MF) and ultrafiltration (UF) can be used instead of sand filters
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Coagulant
•Membrane filtration normally uses hollow fiber bundles that can be submerged or pressurized.
•These membranes can be air scoured , backflushed and cleaned and are not usually sensitive to chlorine.
concentrate
Hollow fiber units consist of tube bundles (UF-MF)
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Pressurized in housing
Submerged in cassette
•Asymmetric membranes are formed by phase inversion and produces anisotropic material.
Membrane Polymers•Polysulfone (PSF),•Polyethersulfone,•Poly(vinylidene fluoride),•Polyacrylonitrile,•Polypropylene.
Source: ZeeweedSource : Pall
Lumen
Permeate
Feed
UF and MF membranes can be “inside-out” or “outside in”
SkinPorous membranes can be backflushed and cleaned.
Mean pore size ~ size rating of filter (.01 -10 micron)
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Source:Koch Membranes
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Cross-flow membrane operationDead-end membrane operation
feed permeate
Primary difficulty with membranes is fouling
permeate
feed
Crossflow operation scours the surface and reduces stagnation near membrane surface.
∆P∆P
Non-porous membranes: nanofiltration, reverse osmosis-thin film composite (TFC)*
Thin (100 - 200 nm) polyamide membrane
Porous support (polysulfone UF membrane)
Woven mechanical support
Surface morphology
thin, dense polymer coating on porous support (composites)
* Discussion will not focus on cellulose acetate asymmetric membranes11
Journal of Membrane Science, 158 (1999) 143-153.Seung-Yeop Kwak, Dae Woo Ihm
Spiral wound membrane has multiple flat sheet “leafs”
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2007 EDS Conference, Halkidiki, GreeceCraig Bartels*, Mashiko Hirose, Hiroki Fujioka*Hydranautics
Reverse osmosis primarily uses polyamide TFC membranes
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RO Plant
•concentration dependent,• membranes susceptible to fouling,• pre-treatment required,
• polyamide membranes degraded by Cl2.
dense polyamide membraneporous polymermechanical support
Thin film composite membrane
polyamide
O
NH
O
NH
NH2
O
saline feedpre-treatment
high pressure pump
post-treatment
fresh water
concentrate disposal
membrane
Reverse osmosis membrane performance measured by four factors
Salt rejection, Water permeability, Fouling (multifaceted), Chlorine tolerance.
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Journal of Membrane Science, 370(2011) 1-22.Kah Peng Lee, Tom C. Arnot, Davide Mattia
Salt
Reje
ctio
n
Normalized water permeability m3/(m2 bar day)
•Modification of PSF substrate• Increase hydrophilicity
•Control of interfacial polymerization• Crosslinking• Membrane thickness• Increase hydrophilicity• Increased chlorine tolerance
•Surface post treatment• Modify surface charge
•Membrane morphology• Surface roughness
•New thin film nanocomposite studies• Polymer with zeolite, Ag, TiO2
Active research topics in RO membrane science and desalination
J. Mater. Chem., 20 (2010) 4551–4566. Dan Li and Huanting Wang
Journal of Membrane Science, 370 (2011) 1-22.Kah Peng Lee, Tom C. Arnot, Davide Mattia
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Materials science has provided major breakthroughs in water treatment
Energy consumption and membrane costs have been reduced by new membrane formulations.
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Journal of Membrane Science, 370 (2011) 1-22.Kah Peng Lee, Tom C. Arnot, Davide Mattia
Salt
Pass
ag
e (
%)
Year
Year
Year
Mem
bra
ne
cost
per
volu
me w
ate
r
En
erg
y r
equir
ed
(kW
h/m
3)
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Membrane surface hydrophilicity enhanced by
surface modification
Surface modification leads to decrease in contact angle;
Less fouling potential, somewhat reduced water permeability
Journal of Membrane Science 371 (2001)293-306.Sanchuan Yu, Zhenhua Lu, Zhihai Chen, Xuesong Liu, Meihong Liu, Congje Gao
Conta
ct a
ngle
(°
)
Coating solution (mg/L)
Membrane smoothness has an effect on
membrane fouling
Journal of Membrane Science188 (2001)115-128.Eric M. Vrijenhoek, Seungkwan Hong, Menachem Elimelech
Smoother membrane surface leads to less fouling
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Membrane degradation by chlorine
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dense polyamide membraneporous polymermechanical support
Thin film composite membrane
Journal of Membrane Science, 300 (2007) 165-171. Guo-Dong Kang, Cong-Jie Gao, Wei-Dong Chen, Xing-Ming Jie, Yi-Ming Cao, Quan Yuan
Membrane degradation proceeds by chlorination of the amide followed by ring chlorination
Chlorine tolerant membranes being studied
A new polymer formulation holds promise as a chlorine tolerant RO membrane.
Angew. Chem. 120 (2008), 6108 –6113.Ho Bum Park, Benny D. Freeman, Zhong-Bio Zhang, Mehmet Sankir, James E. McGrath
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Conclusion
Polymer science and composite fabrication have lead to increased use of membranes and advanced materials in water treatment.
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Microfiltration and Ultrafiltration membranes have provided compact, efficient means of removing suspended solids and wastewater contaminants.
Nanofiltration and RO membranes provide lower energy alternatives for water desalination.
