revised_Application technology hardening in the Water utilities sector

Hardening with CO2 and lime

Adjust hardness and buffer capacity


The natural water component CO2 is an indispensable auxiliary in the targeted hardening of drinking water. The most economical method for increasing water hardness is the use of lime milk or lime water with equilibrium amounts of CO2.


Ca(OH)2 + 2 CO2 ⇔ Ca2+ + 2 HCO3 -

The injection of lime milk and CO2 must be designed in such a way that no scale precipitation occurs at the injection precipitated.

In smaller waterworks, the increase of hardness is often achieved by filtration over a marble filter.

 CaCO3(s) + CO2 + H2O ⇔ Ca2+ + 2 HCO3-

The CO2 required for hardening is added to the water prior to filtration.


No corrosive water
Low operating costs
No scale formation


For the rapid and complete dissolution of CO2, Messer supplies diverse, widely tested technologies, varying from fine-bubble injection directly into the main flow to complete dissolution in a side stream under hydraulically defined conditions. In each project, we specify and offer injection technology that best fits the local conditions. Additionally, we calculate the required CO2-dose

revised_Customer process hardening in the Water utilities sector


Adjusting water hardness

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