Reducing TDS without RO

[sree555]

Is there any method apart from RO by which the TDS could be reduced? For example I have got a well containing 7000ppm TDS and 2000ppm Total Hardness. I would like to utilise this well for industrial purpose for this the TDS should be below 2000ppm and the total hardness <1000ppm. Kindly suggest any method by which TDS could be reduced.

 

[bewdley]

You may think of a precipitation of insolubles (e. g. precipitation of Mg using Ca(OH)2, then Ca using soda ash - it's a classic). Or you may consider crystallisation as in ZED plants. However, economics of these processes are much worse than RO : unless you have something poisoning the membranes, I would suggest to revert to good old osmosis.

 

[bimr]

You can use an evaporator with steam or electricity as the driving force. An evaporator may be more feasible than RO considering your high hardness level. The high hardness level may require pretreatment.

You may also consider Electrodialysis (ED).

It is unlikely that any precipitation process by itself is feasible. Most of the salts are probably as chloride and the precipitation process will have no effect on the chloride ion.

 

[cub3bead]

If your alkalinity is greater than the hardness then you can do a dandy job of reducing the TDS with a weak acid cation (HCl regeneration!)exchanger and a decarbonator. You may not make it to the 2000 TDS spec'ed but you would well down the road.