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


Waste-free watersoftening zu: Abfallfreie Wasserenthärtung
Drinking water purification zu: Trinkwasserreinigung
Purification of aqueous solutions containing
dissolved and emulsified organic compounds
zu: Reinigung wäßriger Lösungen von gelösten und emulgierten Organika
Removal of zinc, lead, copper, cadmium and mercury
from waste water
zu: Abtrennung von Zink, Blei, Kupfer, Cadmium und Quecksilber aus Abwasser
Removal of arsenic from wash solutions of the
sulphuric acid production
zu: Abtrennung von Arsen aus Waschlösungen der Schwefelsäureproduktion


Waste-free Water Softening


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:

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

Throughputs of 1200 - 1500 bed volumes per hour can be realised for both the sorption and the regeneration process. The process is carried out by application of the cation exchanger SGS-polymer type 80. A water hardness of 27.6° dH
(4.93 mmol/l) can be reduced by 95 - 98 % using this SGS-polymer and the capacity reaches values up to 2 mVal/g.

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.


Pattern of structure and function of a device for waste-free water softening


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Last Update:
October 2001
Design by
Steffen Bock Weiland and Roland Kühne  mail