Treatment of Co-Mingled PFAS and 1,4-Dioxane Contamination Using Flow Reversal Reverse Osmosis (FR-RO)

Flow reversal reverse osmosis (FR-RO) technology is evaluated for simultaneous removal of PFAS and 1,4-dioxane in a pilot study at the John F. Kennedy Water Treatment Plant expansion (14.7 to 26.7 MGD). The FR-RO system employs periodic flow reversal with block rotation technology to prevent membrane scaling while achieving 96% system recovery. Results demonstrate complete removal of regulated PFAS compounds (PFOA, PFOS, PFHxS, PFNA) to below detection limits and 1,4-dioxane removal within North Carolina’s health advisory limit of 0.35 µg/L. Stable performance was maintained over three months of pilot operation without chemical cleaning, with normalized salt rejection remaining >99% and differential pressure increasing <15%, indicating minimal fouling and low projected annual CIP frequency for full-scale deployment.