Desalination: Filter System for Well Water

Reverse osmosis works just fine. Town water membrane, a small pump doing about 15 bar, a bit of pipe, etc., etc....

thanks, but wouldn't a r.o. unit use a lot of filter cartridges for sodium level of 1700+ PPM

thanks joe

1500 ppm = .15%, so 20 GPM = 300,000 pounds/day x .15% = 450 pounds/day of salt removed.

reverse osmosis on clean water does not consume the membrane. It justs uses pump power., so you waste the pump energy of 300,000 pounds/day times a drop of 450 feet (the pressure drop of 15 bar).

ion exchange might be cheaper, with a + and - ion stripper that are rcharged by HCl and KOH. You would have to look up what the amount of +and - resins needed.

Might be cheaper.

Thanks for your suggestion on ion exchange. will look into it

joe

That's a lot of salt. Just remember that you're going to have to get rid of the higher salinity water on the "bad" side of the R/O membrane or backwash the ion exchange media a lot. So that's going to add to the stress on the pump and the well's ability to replenish.

I hate to say it but do you have a well or a salt mine?

1700 is not too bad, that would be brackish water desalination. I would go to the web and look up brackish water desalination. RO is typical in western societies. You will generate brine waste that will need to be considered, but all deslaination processes generate brine waste. Depending on the compounds in the waste product, it may be easily disposed of. If you have a more typical ground water problem of very high calcium and magnesium this will not hurt the soil.

May be both

Pre treatment (Pressure Sand Filter) followed Cation Exchange Resin System plus Anion Exchange Resin System

or

Pre treatment (Pressure Sand Filter) followed by RO

will work.

For better economy you may consider both ion exchange + RO together though initial capital cost may be higher.

For pre treatment adding a cogulant may help Sand filter to be more efficient.

To give a more detailed proposal you should give complete chemical & physical properties of water and also the intended use after treatment. (Remember treating water is not very cheap!)