Dual Embossment Modes During Pilot-Scale Ultra-High Pressure Reverse Osmosis of Hypersaline Oilfield-Produced Water: Preferential Scalant Accumulation Along Imprints of Intruded Permeate Spacers

Abstract Desalination of hypersaline brines is garnering increasing interest, which demands novel technologies. To this effect, we report a comprehensive autopsy of pilot-scale ultra-high pressure reverse osmosis (UHPRO) membranes operated in batch mode harvested from a produced water beneficial reuse treatment plant in the Permian Basin, Texas. Physical-chemical alterations of membranes due to operation at 1,650 psi, including dissimilar embossment behavior on either side of the permeate spacer, were diagnosed. On one side, the ridge and valley morphology created by the knitted spacer filaments caused inelastic wavelike membrane deformation. On the other side, spacer filaments were in-plane with each other, which only embossed membranes and did not cause substantial or permanent deformation. Scalants appeared to be preferentially accumulated alongside imprints, suggesting this was an artifact of membrane deformation. In extreme cases, the membranes even developed microcracks. Inorganic scaling and (bio)organic fouling were low, which was attributed to effective pretreatment and judicious UHPRO operation. Aluminosilicates were the dominant inorganic scale, and iodine was evenly distributed across the membrane surfaces. Low amounts of chromium, calcium, magnesium, barium, and iron were heterogeneously deposited across the membranes. Results pointed to the need to develop novel spacers and membrane polymers and to update concentration polarization models, accounting for potential flow heterogeneities introduced by embossment.