Strong Base Anion vs Weak Base Anion

We often are asked “what is the difference between Strong Base Anion (SBA) and Weak Base Anion (WBA) when fed with municipal water?”

From an operational standpoint, when combined with a Strong Acid Cation (SAC) before the SBA or WBA the main difference is run length, quality of water produced and pH of the water produced.

A SAC-WBA combination produces more water at a lower quality than a SAC-SBA. However, the SAC-WBA does not remove weak acids such as silicic acid or carbonic acid. Therefore, the pH of water produced from a SAC-WBA will be slightly lower than neutral.

A SAC-SBA combination produces less water at a higher quality when compared to a SAC-WBA. This combination also removes weak acids and CO2 and in theory should produce purely deionized water with a neutral pH but falls short due to inevitable sodium leakage. This sodium leakage from the SAC combines with OH- from the SBA and produces a small amount of NaOH (Caustic) which is a base and therefore increases the pH slightly over neutral.

It is common for a SAC-SBA set to be placed before a Mixed Bed to remove the bulk of dissolved solids when an RO is not feasible.

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