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Sodium Carbonate (Na2CO3), usually known as Soda Ash, is commonly used in water treatment to increase the pH of acidic water.  Soda ash systems are employed to act as first a pH adjuster with the added benefit of softening of the water.  Soda ash systems are typically used as a point-of-entry injection system.  Corrosion-resistant chemical feed pumps will discharge the soda ash solution into the water to raise the pH.  Alternatively, the solution can be delivered by gravity by utilizing an overflow weir and trough to deliver the soda ash solution to the point of application. 


The carbonate ion is utilized to precipitate out the hardness in water. The primary advantage to using soda ash is that it acts as a water softener, since carbonate can precipitate the calcium and magnesium ions present in "hard" water.  


Soda ash can be used in tandem with a lime treatment system as the lime slurry will remove chemicals associated with carbonate hardness while the soda ash solution will handle the remaining chemicals that cause non-carbonate hardness. These harness causing chemicals precipitate out and are then removed by conventional processes of coagulation/flocculation, sedimentation, and filtration.  This dual treatment method can reduce the amount of CO2 needed to re-carbonate  water to bring the pH of the water down to a stable level and increases cost savings due to the reduced lime usage.

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