Porous membranes in pressure-assisted forward osmosis: Flux behavior and potential applications

In this work, pressured-assisted forward osmosis (PAFO) was performed using porous membranes to achieve higher fluxes. The effects of additional pressure and membrane orientation on membrane performance were investigated. When ultralow additional pressure (0.04 bar) was applied, the water flux at AL-FS orientation (i.e. active layer facing the feed solution) was observed to double. Reverse solute diffusion was also inhibited dramatically at both membrane orientations in PAFO. Filtration tests revealed that porous membranes with ultralow pressure in FO were more applicable than ultrafiltration (UF) because mild condition (i.e., 0.12 bar versus 1.25 bar) is conducive to preserving microalgae cell integrity.