Perspectives for membrane contactors application in water treatment

The possibility to redesign important industrial production cycles by combining various membrane operations is emerging as an attractive opportunity for the rationalisation of chemical productions. The field of applicability of traditional pressure driven membrane operations is today widened by novel membrane systems, such as membrane contactors. Potentialities of these devices have been discussed in the strategic sector of desalination and water treatment; here, despite the great success of membrane technology, some crucial problems still remains unsolved. Membrane absorbers and strippers can be used to control the amount of dissolved gases, thus reducing corrosion phenomena (02 removal), improving water agreeability (H2S removal), adjusting pH (limitation of scaling potential, enhancement of rejection towards boron, control of polymorphism of precipitated species, etc.). Membrane distillation is able to overcome limitations suffered by RO operation, mainly due to concentration polarization phenomenon; as a result, the total water recovery factor can be drastically increased. Membrane crystallizers demonstrate interesting potentialities in the production of crystals from supersaturated solutions showing good structural properties. In addition, the design of the integrated membrane processes well satisfy the requirements for an advanced process intensification approach that, in perspective, promises to surmount the existing limits of industrial processing lines.