Why it is so expensive? What is the technological bottleneck? What is the current state-of-the-art technology and membrane used?
Is there any good paper to read? Thanks!
Because both capital and operating costs are too high. Reverse osmosis membranes are only able to obtain 50% water recovery which makes it not very economically viable. Evaporation technologies requires a very high operating cost since one should provide the water latent heat to evaporate the water and crystallize the salt.
Bottleneck is the nature of the sea water (high TDS, fouling and scaling material, etc.).
Zero liquid discharge technologies such as crystallization, or membrane distillation are among the best candidates for this purpose. However, still not economical. You may check GE ZLD technology.
Forward osmosis is not able to get high water recovery. So the only membrane technology that can offer high water recovery is membrane distillation (to my knowledge).
Many thanks for your answer. Do you have some good reference to suggest?
and another article with I don't manage to upload:
J of Polymer Science Part B: Polymer Physics, Vol 48(2010) p 1685-1715, DOI: 10.1002/polb.22037
Good luck
Michael
Dear Baohua: The cycle of water in earth is a natural phenomenon. From an Engineering point of view, already exist relatively good technologies, particularly with Reverse Osmosis and with thermal desalinization. It is mainly a matter of cost of energy required and productivity when water has to be desalinated at a large scale. Renewable energies can be used and with Reverse Osmosis turbines can be installed to recover energy that would be wasted in the process. Current unitary costs, particularly for drinking water, frequently are not excessively costly. Much fresh water is frequently wasted in the systems of water supply before even reaching the consumers, reaching sometimes losses of 30% to 50% or more from the volumes of production, particularly in old systems, or systems badly constructed. Bad habits of consumers sometimes also do not help, particularly when the cost of water is maintained artificially low.
Thanks António Manuel Abreu Freire Diogo for your answer! If there is a portable system that could produce fresh water serving the local community needs, would it solve the problem?
By saying potable I mean a smaller system that requires less resources to establish the facility and it can be used to recycle water rather than use seawater. Therefore it can be installed in the local community.
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