An Autopsy Study of a Fouled Reverse Osmosis Membrane Used for Ultrapure Water Production

Abstract

This study investigated the fouling and cleaning behaviors of reverse osmosis (RO) membranes in a lab–scale ultrapure water (UPW) production system via membrane autopsies and characterization of dissolved organic matter (DOM) and membrane foulants. Most of DOM were effectively removed by the MFC filter, with the exception of the peak at 150 Da. The RO membranes were effective in reducing conductivity, DOM, total nitrogen (TN), and ultraviolet A (UVA254nm) concentration; the polishing stage using IER filter resulted in ultra-trace levels of all these parameters required for semiconductor manufacturing (> 18.2 ΩM). The quantity of the desorbed RO membrane foulants, in terms of dissolved organic carbon (DOC), varied considerably depending on the type of desorbing agents: 0.1 N NaCl (65.12 mgC m−2) > 0.1 N NaOH (46.14 mgC m−2) > deionized water (25.39 mgC m−2) > 0.1 N HCl (15.95 mgC m−2). The high cleaning efficiency of the salt solution (0.1 N NaCl) was attributed to the efficient desorption of hydrophilic DOM foulants from the RO membrane surfaces. These results demonstrate that the salt cleaning may provide a promising option to recover the performance of the RO membranes fouled primarily by hydrophilic DOM fractions.