Introduction

 

Chloride-cycle dealkalization is an ion exchange-based process designed to remove alkalinity from pre-softened water (i.e., a reliable zeolite softening process is required upfront).  Strong Base Anion (SBA), Type II resin is used to provide ion exchange removal of the alkalinity (HCO₃ and CO₃). 

Strong acid salts, such as sulfate (SO₄) ions and nitrate (NO₃) ions will be removed via this ion exchange process as well.  The resin is regenerated with sodium chloride (NaCl) or with a combination of NaCl and sodium hydroxide (NaOH). Including a small amount of NaOH in the regeneration can significantly improve process efficiency.  Figure one illustrates the ion exchange process as it occurs in the system.