Effect of Coexisting Natural Organic Matters (NOM) on the Rejection of Endocrine Disrupting Chemicals (EDCs) by a Low Pressure Reverse Osmosis (LPRO) Membrane

The coexisting natural organic matters (NOM) in the water environment are expected to influence rejections of endocrine disrupting chemicals (EDCs) in membrane filtration. However, such influences and rejection mechanisms are not well understood. This paper aims to elucidate on the rejection of three representative EDCs: Bisphenol A (BPA), 17~-estradiol (F2) and 4-Nonylphenol (NP) by a LPRO membrane (UTC-60) with and without three representative NOM: humic acid (HA), fulvic acid (FA) and effluent organic matters (EfOM) in solutions by laboratory experiments. The EDCs rejections were enhanced with increasing solution pH and negative membrane zeta potential as a result of decreased membrane pore size. Adsorption of the EDCs on membrane surface and size exclusion were the most likely rejection mechanisms in absence of the NOM. Coexistence of the NOM in solutions, in general, enhanced the EDCs rejections. However, no specific trends in rejection were observed possibly due to diffusion of the adsorbed NOM and EDCs molecules through the membrane pores, physicochemical properties of the EDCs and several types of NOM molecules present in EfOM. The EDCs adsorption on NOM molecules and their adsorption on the membrane surface and/or retention by size exclusion were the most likely rejection mechanisms.