Integrated membrane operations for seawater desalination

Reverse osmosis is widely applied to water desalination because of the relatively low cost of the process. Besides the well defined role that this technology plays in the desalination scenario, in the last years, from all over the world, demand for lower costs and higher quality of water has been advanced. Integrated membrane processes represent an attractive opportunity because of the synergic effects that can be reached, the simplicity of these units, and the possibility of advanced levels of automatisation and remote control. Moreover, the integration of different membrane units represents an interesting way for reaching the process intensification goals due to the possibility of overcoming the limits of the single units and, thus, to improve the performance of the overall operation.

In this work the potentialities of an integrated membrane desalination system have been experimentally verified. The achieved results confirm the interest in operating by combining different membrane units. In particular, the presence of the NF as pretreatment allows to increase the water recovery of the RO unit up to 50%. Moreover, introduction of a membrane crystallizer leads to a 100% recovery and elimination of the brine disposal problem, representing the pure crystals produced a valuable product. From this preliminary analysis, adoption of integrated membrane systems appears an interesting possibility for improving desalination operations and meeting the increasing pure water demand.