[birdzoom (OP)]

I am writing some sci-fiction stuff and would like to know about the possibility of removing Na-Cl from seawater or somehow breaking it down to something else with the help of microorganisms. How possible is it?

[birdzoom (OP)]

Or some kind of Algae that would convert the Na-Cl in sea water with the help of sunlight to some energetic compound....

[Joe L. Ogan]

It does seem extremely unlikely.  Thanks for comments.  Joe L. Ogan

[RD]

These links may be of use

http://en.wikipedia.org/wiki/Bioremediation

http://en.wikipedia.org/wiki/Halophile

[CliffordK]

Your problem with a bacteria approach is that you have to do something with the Sodium Chloride.  And, since it is an ubiquitous salt, it will be hard to put it somewhere better.  And, it would be difficult for a bug to precipitate it out (without making something else like calcium chloride).

Some other chemicals can be fed to micro-organisms, then filter out the micro-organisms.  This might work to some extent, but it wouldn't be very efficient, in part because of osmosis.

And...  no "bug" could force a nuclear reaction to convert Sodium/Chloride into something else.

One could imagine a bug that could eat NaCl and release Cl₂ gas, but you would still have the Sodium to get rid of, and they won't like sodium metal.

Other than distillation, another "real" method of getting rid of Sodium Chloride is an osmotic filter.

[imatfaal]

How does osmosis help filter salt from water.  My hazy recollection is that water passes through the semi-permeable membrane down the water gradient to attempt to equalize the the concentration on both side. 

So at the start you have
100ml clean water | 100ml salty water 
and at the end you have
<100ml clean water| >100ml slightly less salty water

I must be missing something as this seems to give you less clean water and more brine.  I could see desalination working through REVERSE osmosis - but this is by no means passive and requires energy input

[CliffordK]

Ahh... yes...
"Reverse Osmosis" using a pressure difference to form the gradient across an "osmotic barrier".

http://en.wikipedia.org/wiki/Reverse_osmosis

Whew...  apparently it takes 600-1000 PSI to overcome the osmotic gradient in seawater.  I didn't realize it was so high.

Which then brings up the off-topic question on whether the gradient could be utilized to generate power.  And, apparently someone has already thought of that   [xx(]

http://en.wikipedia.org/wiki/Osmotic_power

I suppose that osmosis is the reason why it would be difficult to get a "bug" to desalinate something like sea water, as they can not fully overcome the osmotic gradient in their cell walls.