N-Nitrosodimethylamine (NDMA) Precursors Leach from Nanofiltration Membranes

摘要

Membrane filtration processes have been widely used as effective means of providing safe and reliable water for both potable and nonpotable purposes. In our laboratory, we have observed that N- nitrosodimethylamine (NDMA) precursors leach from virgin mem- branes. Therefore, in this study, we aimed to examine (i) the potential leaching of NDMA precursors from different types of nanofiltration membranes and (ii) membrane cleaning techniques using different types of background solutions to prevent the leaching. The results showed that for three different types of nanofiltration membranes, leaching of high levels of NDMA precursors (～180-450 ng/L) was observed. Leaching continued even after membranes had been washed with ～3900 L of distilled deionized water/m2 . Among various cleaning techniques, washing the membrane with a 1 mg/L Cl2 solution was found to be the most effective for reducing the extent of NDMA precursor leaching.