Recent Advances in Membrane Characterization, Fabrication and

Process Technology at the Singapore Membrane Technology Center

William B. Krantz, Ph.D., P.E.

Professor Emeritus & Presidentâ??s Teaching Scholar Department of Chemical & Biological Engineering University of Colorado

Boulder, Colorado 80309-0424 U.S.A.

An overview will be given of advances in membrane characterization, fabrication and process technology developed and patented by the Singapore Membrane Technology Center (SMTC). These include: evapoporometry (EP) for characterizing the pore-size distribution (PSD) of membranes; novel silver nanoparticle-impregnated hydrogels for the production of potable water in disaster-relief applications; and a hybrid membrane process that can achieve a higher recovery at a lower pressure and a lower specific energy consumption (SEC) than conventional single-stage reverse osmosis (SSRO). EP is based on the principle that the vapor pressure is affected by the curvature of a volatile liquid contained in a porous material, which is described by the Kelvin equation. Application of EP to characterize the PSD of flat sheet and hollow fiber membranes as well as biofilms will be discussed as well as its use to assess internal pore fouling. The novel silver nanoparticle-impregnated hydrogels developed by the SMTC can sorb
100 times their weight in water while achieving a 6-log reduction in biocontaminants. Potable water then can be recovered by simple compression of the swollen hydrogels. The SMTC has
also develop a novel energy-efficient reverse osmosis (EERO) process for water desalination
that combines single-stage reverse osmosis (SSRO) with a countercurrent membrane cascade with recycle (CMCR). By the judicious combination of SSRO and a CMCR while employing countercurrent flow of the retentate and permeate, permeate recycle, and retentate recycling made possible by the use of at least one NF membrane stage, this EERO process can achieve an overall water recovery as high as 75% at a significantly reduced osmotic pressure differential and reduced specific energy consumption (SEC) relative to SSRO.