5.14.2 Reverse osmosis
This technique, explained in Section 3.8.1, is rapidly becoming a major means of desalination, with research producing membranes with lower operating pressures (and hence lower operating costs). Originally a pressure of 14 × 106 Pa was needed to separate pure water from sea water but with newer membranes only half this pressure is required. Reverse osmosis membranes operate at ambient temperature, in contrast to multistage flash distillation, and this lower temperature minimises scaling and corrosion problems. To prevent problems with organic fouling of the membrane, pretreatment of the feed water is required.