Desalination...sand filtration...help?

Question

A new resort on an island in the sea is being built and the designers would like to pump water from the sea and send it through a home made sand filter. Can anyone help me find some information/research on this cost efficient method or any other low tech solutions? thanks a lot!

Answer 1

If you pump sea water through a sand filter; no matter how well it is made; all you'll get will be very clear salt water.  You need to either distill the water to remove the salt; or use a system incorporating ion exchange resins that will absorb the salt.  Both are rather expensive operations.

Answer 2

the sand filter would only clear the water, it would not affect the salinity of the water.  sand filters are commonly used in  wastewater treatment to remove the solids from the wastewater, thus producing a clear effluent.

to remove the salts, you would have to use reverse osmosis or distill the water.  neither option is low cost as great amounts of electricity would need to be used for either.