**7. Summary**

PEG, its derivatives, and copolymers are water soluble depending on their molecular weights, terminal, and copolymer blocks. They have widely been utilized in membrane fabrications and performance tests of some membranes due to the nature of hydrophilicity of these polymers. This chapter focuses on PEG applications in two emerging membrane technologies FO and MD. With regard to FO, PEG can not only be integrated into some draw solutes for easy draw solute recovery but can also be applied to the support and active layers for improving membrane antifouling properties. On the other hand, PEG is mainly used as pore-forming additive in the MD membrane fabrication. Compared to the control membranes in the various studies which are summarized here, PEG-assisted FO and MD membranes exhibit better overall performance for wastewater treatment and desalination according to water flux, flux recovery after cleaning, and antifouling behaviors.
