• Thin polyamide films with controlled thickness are deposited directly on electrodes.

  • EIS measurements are made with varying polyamide film thicknesses and salt solutions.

  • Impedance spectra are fit with equivalent circuits containing resistors and capacitors.

  • Polyamide films exhibit a characteristic low-frequency impedance response.​

  • Salt permeability is calculated from the characteristic polyamide membrane resistance.

  • Membrane transport behavior is directly observed during forward osmosis permeation.

  • Incomplete wetting of membrane polysulfone support layer is visually confirmed.

  • Draw solute concentration is quantified across feed and draw solution channels.

  • Permeation models are evaluated for describing observed concentration polarization.

  • Polyamide films and membranes are fabricated by molecular layer-by-layer deposition.

  • Polyamide surface chemistry is enriched with amine or carboxyl functional groups.

  • Gypsum scaling is compared for homogeneous and heterogeneous nucleation conditions.

  • Long-term gypsum scaling is similar for polyamide with different surface chemistry.

     

  • Commercial forward osmosis membranes are modified for organic fouling resistance.

  • Modification conditions for the poly(ethylene glycol) block copolymer are optimized.

  • Membranes show fouling resistance with an aggressive organic foulant mixture.

  • This post-fabrication technique compares favorably to other modification methods.

  • We present a critical review of the current state of forward osmosis (FO).

  • We analyze the energy efficiency of FO and emphasize relevant applications.

  • We discuss the key required membrane properties for FO and future implications.

  • We highlight fouling reversibility of FO and relevant benefits and applications.

  • We discuss applications where FO outperforms current technologies.

  • We present a low-fouling thin-film composite forward osmosis membrane.

  • An amine-rich polyamide active layer facilitates surface functionalization with PEG.

  • Improved organic fouling resistance at high (250 mg/L) alginate feed concentration

     

     

  • An analysis of an integrated forward and reverse osmosis desalination process is presented.

  • Integrated process can achieve boron and chloride levels suitable for agricultural irrigation.

  • Integrated forward and reverse osmosis process consumes less energy than a conventional two-pass RO process.

  • Challenges to further development of the integrated process are discussed.