The Importance of Reverse Osmosis in Removal of Notification Level Chemicals and Selected Endocrine Disrupting Chemicals - A Pilot Study

Information regarding rejection capabilities of RO to “DHS notification level chemicals” and EDCs is very limited. In this study, a pilot scale MF/RO receiving secondary treated wastewater effluent from Big Bear Area Regional Water Agency (BBARWA) WWTP was tested to determine the rejection capabilities of the RO membranes for specific non-regulated compounds and CDHS specified EDCs. Due to domestic nature of BBARWA wastewater and the degree of secondary treatment provided, with the exception of boron and chlorate, all DHS notification level compounds were below their detection limits in the RO feed water. For the detected compounds, the RO exhibited 94 percent rejection capability to chlorate while rejecting boron only 44 percent. EDC testing results have shown that with the exception of 4-methyl phenol, the RO exhibited very good rejections to the tested EDCs. In this study a very good correlation between RO rejection and molecular size, polarity and solubility of the compounds. On the other hand, no good correlation between RO rejection and octanol water partition coefficient (Kow) of compounds was found thereby suggesting that Kow alone is not sufficient to describe rejection of non-polar compounds by the RO membranes.