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-AC04-94AL SAND No P

Introduction Water treatment processes Materials science for water infrastructure Membrane technology- polymeric Micro and ultrafiltration (MF and UF) Nanofiltration and reverse osmosis (NF and RO) Recent RO membrane advances 2

3 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

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5 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) Alyson Sagle and Benny D. Freeman,

Coagulation Flocculation Sedimentation and or filtration 6 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 7 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

8 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: Zeeweed Source : Pall

Lumen Permeate Feed UF and MF membranes can be “inside-out” or “outside in” Skin Porous membranes can be backflushed and cleaned. Mean pore size ~ size rating of filter ( micron) 9 Source: Koch Membranes

10 Cross-flow membrane operation Dead-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

Non-porous membranes: nanofiltration, reverse osmosis-thin film composite (TFC)* Thin ( 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 membranes 11 Journal of Membrane Science, 158 (1999) Seung-Yeop Kwak, Dae Woo Ihm

EDS Conference, Halkidiki, Greece Craig Bartels*, Mashiko Hirose, Hiroki Fujioka *Hydranautics

13 RO Plant concentration dependent, membranes susceptible to fouling, pre-treatment required, polyamide membranes degraded by Cl 2. dense polyamide membrane porous polymer mechanical support Thin film composite membrane polyamide saline feed pre- treatment high pressure pump post- treatment fresh water concentrate disposal membrane

 Salt rejection,  Water permeability,  Fouling (multifaceted),  Chlorine tolerance. 14 Journal of Membrane Science, 370(2011) Kah Peng Lee, Tom C. Arnot, Davide Mattia Salt Rejection Normalized water permeability m 3 /(m 2  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, TiO 2 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) Kah Peng Lee, Tom C. Arnot, Davide Mattia 15

Energy consumption and membrane costs have been reduced by new membrane formulations. 16 Journal of Membrane Science, 370 (2011) Kah Peng Lee, Tom C. Arnot, Davide Mattia Salt Passage (%) Year Membrane cost per volume water Energy required (kWh/m 3 )

17 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) Sanchuan Yu, Zhenhua Lu, Zhihai Chen, Xuesong Liu, Meihong Liu, Congje Gao Contact angle (°) Coating solution (mg/L)

Membrane smoothness has an effect on membrane fouling Journal of Membrane Science188 (2001) Eric M. Vrijenhoek, Seungkwan Hong, Menachem Elimelech Smoother membrane surface leads to less fouling 18

19 dense polyamide membrane porous polymer mechanical support Thin film composite membrane Journal of Membrane Science, 300 (2007) 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 20

Polymer science and composite fabrication have lead to increased use of membranes and advanced materials in water treatment. 21 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.