Water Science

Rejection efficiency of water quality parameters by reverse osmosis and nanofiltration membranes

You are viewing information about the paper Rejection efficiency of water quality parameters by reverse osmosis and nanofiltration membranes.

Journal: Environ Sci Technol 2003/10/24
Published: 2003
Authors: Peng, W.;Escobar, I. C.
Address: Department of Civil Engineering, University of Toledo, Toledo, Ohio 43606, USA.

The objective of this study was to evaluate the effectiveness of reserve osmosis (RO) and nanofiltration (NF) membranes, under various solution chemistries, on water quality. The effects of organic carbon, divalent and monovalent cations, bacteria, and permeate drag on the rejection efficiencies of three different membranes were investigated through a series of laboratory bench-scale experiments. Quantitative models were successfully developed to predict the rejection of turbidity, divalent and monovalent cations, ultraviolet absorbance at 253.7 nm (UV254), and dissolved organic carbon (DOC) by membrane filtration. It was found that mechanical sieving (measured as molecular weight cutoff, MWCO) and electrostatic interactions were the most significant parameters since they were found to be important in nearly all models developed. For negatively charged membranes, under high ionic strength solution environments that repress electrostatic interaction between charged compounds and membranes, passage of compounds was mainly a function of size exclusion (i.e. MWCO). Further, of the feedwater parameters tested, bacteria concentration was observed to be the most significant influence on UV254, divalent cation and monovalent cation rejections. The developed models revealed that interactions between feedwater composition and membrane properties impacted the rejection efficiency of membranes as significantly as water composition and membrane properties individually.

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