Reverse osmosis (RO) has become the method of choice for reclaiming high quality water from municipal effluents. However small uncharged molecules, such as N-nitrosodimethylamine (NDMA), can pass through RO membranes and may require extra treatment.  Water of wastewater origin often exhibits a strong propensity for biological fouling even when pretreated by microfiltration. Fouling lowers the rejection of solutes. In this study 6 nitrosamines including NDMA were used to evaluate the effect of biofilm formation on organic solute rejection. Compound transmission was measured with flat-sheet test cells equipped with NF90 membranes. Membranes were covered with biofilms by inoculating the feed tank with a culture of Curvibacter sp. while recirculating minimal salt medium.  After 28h of incubation, the biofilm was ~80 �m thick and covered the entire sheet. The unfouled membrane rejected nitrosamines with efficiencies ranging from 24% for NDMA to 85% for N-nitrosodipropylamine.  The biofilm lowered nitrosamine rejection by 15-20%.

Transport of nitrosamines across biofouled reverse osmosis membranes

243rd National Meeting (2012)

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