Chapter 4 Desalination: Reverse Osmosis and Membrane Distillation

Reverse osmosis (RO) and membrane distillation (MD), the two important applications associated with membrane-based desalination, are discussed in detail. Various RO process parameters, such as membrane synthesis, materials involved, and fouling control, play vital roles in the success of membrane filtration. The membrane synthesis process has a large influence on the physical and mechanical properties of the membrane. It also influences crucial filtration parameters such as pore size distribution and membrane strength. Furthermore, properties of the membrane are characteristic of the polymers used for membrane synthesis. Hydrophilicity and/or hydrophobicity, surface charge, and solute diffusion coefficients are all functions of the polymers used in membrane synthesis. Depending on the nature of feed waters, as well as available resources, an appropriate variation of these parameters results in an optimum desalination process. However, both RO and MD processes are deeply plagued by membrane fouling. Fouling is influenced by various parameters concerning the nature of both feedwater and polymeric membrane material. Careful understanding of process functioning can result in reducing the fouling problem. An assortment of fouling prevention and membrane cleaning techniques are discussed in this chapter.