The rejection of endocrine disrupting and pharmaceutically active compounds by NF and RO membranes as a function of compound and water matrix properties

This study examined the rejection of 22 endocrine disrupting compounds (EDCs) and pharmaceutically active compounds (PhAC) from raw and 5-μm filtered Lake Ontario water, membrane bioreactor effluent and laboratory-grade water (Milli-Q®) by ‘loose’ and ‘tight’ nanofiltration (NF) membranes and a reverse osmosis (RO) membrane. Rejection by the ‘tight’ NF membrane was most strongly correlated with compound log Kow and water solubility with the more hydrophobic compounds showing higher rejection. The RO membrane provided efficient EDC and PhAC removal (>90%). Conversely, in general, the ‘loose’ NF membrane offered poor and variable compound removal. Fouling and the presence of organic matter likely contributed to higher rejections of EDCs and PhACs while higher concentrations of divalent ions appeared to result in lower EDC and PhAC rejection by the membranes.