Softening of drinking water by ion exchange

The Danish waterworks Juelsminde has installed a central water softening system based on ion exchange. An important parameter for choosing ion exchange was the simple operation of the system and that it could be placed in the existing building of the waterworks.

In ion exchange, calcium and magnesium are removed from the water and replaced with sodium - which can be compared to common table salt. The residual product of ion exchange is salty water. Typically, the water would be discharged to the sewer, but as the waterworks of Juelsminde is located close to the sea, they have received approval to discharge the waste water into a canal 20 meters from the sea. Here it is mixed with already salty seawater. 

Juelsminde Waterworks has gone from a hardness of 19 °dH to 8 °dH. To achieve the desired hardness, a partial flow of up to 32 m3/h is softened and then mixed with hard water. This makes the solution flexible in relation to a change in hardness, e.g. when drilling a new well.