Membrane contactors for innovative sustainable desalination systems

Desalination, and in general water treatments and reuse, will become one of the most traditional processes in the next few years due to the increasing of the world population, growing standards of living, increasing necessity of removing from waters species not compatible with our biological and physiological mechanisms. Water treatments and specifically desalination will also have to be relatively of low cost and sustainable in their characteristics. Membrane operations are already having an important role in the world wide desalination engineering and the anticipations of their future role are quite positive. However, they have to show their capability in solving problems today existing as fouling and biofouling, brine disposal, cost reductions etc. The overall strategy of process intensification will have to be considered in realizing future large scale desalination systems, where automatization, remote controls, significant size reduction referred to their productivity etc., will have to be present. Integrated membrane systems based on UF, NF and RO all acting together have been already demonstrating their potentialities. Further improvements in desalination plants might be considered introducing new technologies for overcoming the exiting limits. Membrane contactors for controlling gases concentrations as CO2 , O2, etc. in the water; membrane distillation and membrane crystallizers for increasing the recovery factors of the NF and RO units, reducing also the brine problems by forming crystals of economic interest (such as MgSO4 p.e. in NF, or NaCl in RO) are typical cases under investigation. In this paper, experimental results reached in a possible integrated membrane desalination systems will be described where MF, NF, membrane strippers, RO and membrane crystallizers are working. A tentative cost and energetic analysis is also presented.