M. Son, W. Yang, S.S. Bucs, M.F. Nava-Ocampo, J.S. Vrouwenvelder, B.E. Logan
Environmental Science & Technology, volume 5, Issue 9, pp. 584-590, (2018)
Reverse osmosis (RO) membranes inevitably foul because of the accumulation of material on the membrane surface. Instead of trying to reduce membrane fouling by chemically modifying the membrane, we took a different approach based on adding a sacrificial coating of two polyelectrolytes to the membrane. After membrane fouling, this coating was removed by flushing with a highly saline brine solution, and a new coating was regenerated in situ to provide a fresh protective layer (PL) on the membrane surface. The utility of this approach was demonstrated by conducting four consecutive dead-end filtration experiments using a model foulant (alginate, 200 ppm) in a synthetic brackish water (2000 ppm of NaCl). Brine removal and regeneration of the PL coating restored the water flux to an average of 97 ± 3% of its initial flux, compared to only 83 ± 3% for the pristine membrane. The average water flux for the PL-coated membranes was 15.5 ± 0.6 L m–2 h–1 until the flux was decreased by 10% versus its initial flux, compared to 13.4 ± 0.5 L m–2 h–1 for the nontreated control. The use of a sacrificial PL coating could therefore provide a more sustainable approach for addressing RO membrane fouling.