Pilot-Scale Evaluation of Spiral-Wound Modules in Osmotically Assisted Reverse Osmosis

The osmotically assisted reverse osmosis (OARO) process is gaining attention for cost-effective aqueous solution concentration. However, there is a lack of pilot-scale studies. This research used two spiral-wound modules in a pilot-scale plant. The first one, an adapted commercial reverse osmosis module, showed no positive results, likely due to excessive membrane thickness and high internal concentration polarization. In contrast, the second one consisting of a novel forward osmosis prototype demonstrated promising outcomes, achieving water fluxes exceeding 2 L m⁻² h⁻¹ even at high salt concentrations (50 g L⁻¹) and relatively low applied pressures (above 12 bar). The study highlights OARO potential, underscores limitations, and emphasizes the need for dedicated module design.