The “hardness” in water is caused by the presence of any polyvalent metallic cation. While several type of cations can be present in the water, typically manganese and calcium represent the predominant majority of minerals found in water. Total water hardness is defined as the addition of these elements and is generally represented as milligrams/liter of Calcium Carbonate.
Hard water needs to be softened in order to reduce scale-forming tendencies, remove radium 226 and 228 and other minerals as well as reducing the turbidity.
There are two main processes for water softening:
1) Chemical Precipitation Lime Softening Process: On this method lime is utilized as water softener, this compound reacts with carbon dioxide and carbonate hardness in order to precipitate calcium carbonate and magnesium hydroxide. This process involves several complicated and dynamic chemical reactions. Nonetheless, there are some simplified methods do obtain the required lime dosing.
The Lime softening process can be: Straight Lime, Excess Lime and Split Treatment. This method has been almost totally replaced by the ion/exchange process, however some specific applications still use lime softening.
2) Ion-Exchange: Nowadays, Ion-Exchange is the most common process for water softening. It also represents the most popular ion-exchange application.
Typically a strong acid cation (SAC) resin is used due to is capacity to remove carbonate and noncarbonate hardness besides, they can operate over a wide pH range. Sulphide-based resins are normally used. Being a reversible reaction, the regeneration of the resin is achieved utilizing an excess of HCL or NaCl depending on the resin type.
An efficient water softening system combines an accurate process selection and design in order to meet the requirements of the client. With over 2950 projects worldwide and more than 300 years of combined experience let Napier-Reid be your single solution for water softening.