BENCH-SCALE TESTING OF SURFACTANT-MODIFIED REVERSE OSMOSIS NANOFILTRATION MEMBRANES/

An homologous series of polyethylene-oxide surfactants, with either oc tylphenol or polypropylene oxide ''head'' groups, were applied to comm ercial cellulose acetate blend (CA) and polyamide (PA) reverse osmosis (RO) and nanofiltration (NF) membranes. The pressure-normalized perme ate flow (NPF) and salt rejection were evaluated before and after foul ing with a vegetable protein broth. Surface changes were characterized using atomic force microscopy and electro-kinetic analysis. The trans port results from both the swatch and element testing were used in a s imple economic model to assess operating costs. Results indicate that cost savings are possible based on the changes in NPF and salt rejecti on.