Assessing bacterial infiltration through reverse osmosis membrane

The attenuation of pathogenic microorganisms in potable water reuse is critical to ensure recycled water safety. Thus, this study sought to identify bacterial communities capable of passing through a commercial reverse osmosis (RO) membrane as well as to characterize the passage of these bacteria through the membranes. Three-quarters of the bacteria in the RO permeate were found to belong to the Burkholderiaceae family, although this family only accounted for 0.2% of the RO feed (i.e., ultrafiltration-treated wastewater) bacterial composition. The infiltration routes of bacteria through the RO membranes was also evaluated using a unique approach—capturing bacteria-sized surrogates (i.e., 0.5 μm fluorescent (FL) microspheres) with a track-etched micro-filter after passing through the RO membrane. Our results demonstrated that a considerable number of FL particles passed through the membranes that were obtained from an RO membrane element. Overall, it was determined that certain bacterial families in wastewater could pass through the passage located in the entire surface of the RO membrane rather than in localized areas. Thus, this study highlights the need to reinforce RO membrane integrity in order to ensure the safety of recycled water for potable water reuse.