AWWA MTC61149

The objective of this study was to examine some of the mechanisms responsible for the passage of organic and inorganic solutes through nanofiltration/reverse osmosis (NF/RO) membranes by running permeation tests, developing hydraulic model and characterizing relevant membrane properties. The materials used included Rhodamine-WT, a chemical with molecular weight of 480 Daltons and approved for use as a tracer chemical in drinking water. It was used as a surrogate for organic solutes. The inorganic solute studied was sodium arsenite, a relatively common water contaminant, which is hard to remove by most conventional water treatment techniques. Permeation tests involved lab-scale experiments performed with a closed-loop system consisting of two flatleaf cells connected in series. Analytical methods involved measuring R-WT concentration using a Bowman Series 2 Luminescence Spectrometer. An excitation wavelength of 555 nm and an emission wavelength of 585 nm were used. The minimum detection level was 50 ng/L. Partition experiments and Rutherford Backscattering (RBS) are discussed. Includes 4 references, tables, figures.