2011 Salinity Summit Contributions to Permeation Resistance in a VSEP RO System Treating Brackish Water or Brine Mark Benjamin and Wei Shi Department of Civil and Environmental Engineering, University of Washington, Seattle, WA 98195

Reverse Osmosis (RO) Reverse Osmosis (RO): Increasingly used in treatment of brackish water and brine for potable water Fouling: Production Time Pressure Time Constant Pressure Constant Production

VSEP Vibratory Shear Enhanced Processing Source: New Logic Research Inc. Emeryville, CA Shear

VSEP Applications Landfill Leachate Manure Management Mining Petroleum Processing Pulp and Paper Desalination

VSEP Operation Amplitude: 13° Frequency: 55Hz TMP: 140 psi

RO Feed Composition Brackish water* Brine: 10 times as concentrated pH8.0Cl175 Ca275 as CaCO 3 Ba25 Mg100 as CaCO 3 Si5 SO 4 350Fe0.5 Na175Alk150 as CaCO 3 TDS1050 * All units in mg/L, except for pH

Permeate Flux Brackish solution Brackish solution

Permeate Flux Brine

Resistance Breakdown RmRm R TOT RπRπ RFRF RFRF = R TOT –R m –R CP –R π R CP

Contributions to Resistance w/ w/o vibration Brackish solution Brackish solution

inlet outlet S1 S2 S3 S4 w/o Vibration w/ Vibration Higher Shear

Painted Membrane Tests Shaded Area Ring for permeation (Jaffrin et al. 2002) r A

Painted Membrane Tests

Mechanisms to Generate Shear Membrane Rotation Ultrasound Longitudinal Vibration Shear- fouling relationship Shear- fouling relationship Torsional Vibration

Conclusions Membrane vibration  Increases permeate flux  Reduces the contribution of fouling to the total resistance  Changes scale morphology into more porous structures Shear Rate  Governs fouling of RO membranes  Facilitate the design of similar systems for fouling prevention/reduction

Acknowledgements This work was supported by the Water Research Foundation (WRF) *. The authors thank New Logic Research, Inc., for providing the test unit. Yujung Chang and Pierre Kwan of HDR, Inc., and Sommer Carter of NLR provided valuable technical assistance during the project. *The views expressed are those of the authors and do not necessarily reflect those of WRF.

RO Membranes inlet outlet 0.9 cm 10.0 cm cm MembraneBW-30FE MWCO (da)5030 MaterialPolyamide pH T max ( o C)7060 Cl 2 Tolerance (mg/L) <0.1 Flux* (L/m 2 ‑ h) 7190 VendorFilmtecSaehan *At a TMP of 2068 kPa

Solute Rejections Brackish solution Brackish solution Brine

Solid Precipitation EDAX spectrum of scales on the membrane surface

Gypsum Aragonite Solid Precipitation - XRD XRD spectrum of precipitates in the feed solution