(691a) Fouling and Cleaning Behavior of Forward Osmosis Membrane (keynote)

Forward osmosis (FO) is considered a promising process in sea/brackish water desalination and wastewater reuse. FO membrane process uses natural osmotic pressure generated by a concentrated draw solution to pull water across a semi-permeable membrane from the feed solution. The diluted draw solution is then reconcentrated to recycle the draw solution as well as to produce purified water.  Compared to conventional pressure-driven membrane processes (i.e. reverse osmosis/nanofiltration), FO process has the potential to reduce energy consumption and generate less brine discharge.  In addition, our study found that the lack of hydraulic pressure in FO membrane operation is advantageous in terms of minimizing irreversible membrane fouling.  Many types of membrane fouling (e.g., alginate fouling, gypsum scaling) in FO processes can be fully reversed by rinsing with pure water without using chemical cleaning reagents.  This talk will focus on the fouling and cleaning behavior of single foulants (alginate, BSA, gypsum) as well as that of combined foulants in FO membrane processes.  A microsope-equipped direct observation setup is used to monitor fouling layer formation on membrane surfaces through a glass window to characterize the kinetics of membrane fouling and cleaning. The adhesion force between foulant and membrane surface is determined by atomic force microscopy (AFM) to better understand the fouling mechanisms.