Demineralization Plants

Additional Details

A standard dual bed ion exchange unit consists of a strong acid cation resin that exchanges hydrogen for positively charged cations present. The second step is a strong basic anion resin that exchanges hydroxide for negatively charged anions present in the water stream. The hydrogen (H+) from the cation exchanger and hydroxide (OH-) from the anion exchanger create the HOH or deionized water to be reused in the process.

There are certain processes that generate an abundance of either a cation or an anion. If this occurs, a more selective weak acid cation can be used to exchange the multi-divalent heavy metals that are in abundance. This "pretreating" of the heavy metals will assist in the exchanging of the mono-divalent cations. A weak basic anion before the strong basic anion can be implemented to assist in better deionizing the water fed back to the process.

The cation ion exchange resin is regenerated with an acid to exchange the hydrogen back onto the cation resin beads. The anion is regenerated with sodium hydroxide to exchange the hydroxide back onto the anion resin beads. The cost and wastewater associated with the regeneration of the ion exchange media is minimal.