SGS-Polymers (Application fields) - Waste-free Water Softening -

Waste-free watersoftening
Drinking water purification
Purification of aqueous solutions containing dissolved and emulsified organic compounds
Removal of zinc, lead, copper, cadmium and mercury from waste water
Removal of arsenic from wash solutions of the sulphuric acid production

There are several methods for the removal of water hardness forming calcium and magnesium salts from drinking and industrial used water. A frequently used method for water softening is the ion exchange.

Normally, columns filled with granular cation exchanger (Na⁺-charged) are applied in ion exchange processes. While the water runs through the ion exchanger bed sodium ions are exchanged against hardness forming calcium and magnesium ions. The used flow rate differs between 5 and 30 m/h. If the ion exchanger is charged with calcium and magnesium ions, it is regenerated with 5 -10 % solution of common salt (sodium chloride). This procedure has some considerable disadvantages:
 

• low throughputs (10 - 50 bed volumes per hour),
• large facilities,
• coming up of huge amounts of salt containing eluate.

If SGS-polymers are used for ion exchanging  processes due to their high exchange rate

• the efficiency of the processes can be increased,
• a nearly waste-free process can be realised
• and the used apparatuses can be simplified.

In this procedure sodium sulphate is used for the regeneration of the charged ion exchanger. Slightly soluble sulphates of hardness forming cations are precipitated during the regeneration. The deposition happens in a separate precipitator and not in the filter element because throughputs of 2000 l/h can be realised. A clear solution of sodium sulphate is received in the precipitator within 20 to 30 min. This solution can be re-used in the regeneration process.
 
 

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Last Update: October 2001

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