Membrane Distillation and Forward Osmosis: Advances in Membranes,

lthough membrane distillation (MD) and forward osmosis (FO) techniques have had a long gesta-tion, they are attracting renewed interest for future applications in reuse and desalination. Both processes are low pressure and well suited for using low-grade waste heat or solar energy, which enable low greenhouse-gas emissions per unit of water produced. However, both pro-cesses require specialized membranes for optimal perfor-mance; module design and operation also have unique challenges.