Running the Resin Sample Trial

Regeneration of Resin Bed
The simplest, most common regeneration method is co-flow (often referred to as co-current), where the regenerant passes down through the resin in the same direction as the service flow. In co-flow regeneration, the first stage of every regeneration cycle is to backwash the bed to relieve compaction and remove suspended matter.

Solutions (or water) above trace solids levels should be filtered before entering the test column. The regeneration solution is passed through the resin at a slow rate to allow adequate contact time.  This is followed by a slow displacement rinse and then a final fast rinse. In laboratory work, demineralized water is preferred for regenerant dilution and the rinsing stages. This will make capacity calculations easier and ensure there is no ionic loading of the resin.

A more efficient and thorough regeneration can be achieved using counter-flow regeneration (often referred to as counter-current or reverse flow). Counter-flow regeneration will produce lower leakage from the bed and better regenerant efficiency.  The regenerant passes in the opposite direction to the service flow. Counter-flow regeneration is somewhat difficult to set up in a laboratory, and parameters such as bed depth are more critical.

Additionally, it is vital to prevent the bed from fluidizing when the regenerant is passed in an up-flow direction. Place cotton or glass wool on top of the resin to fill the freeboard space to prevent fluidization. This will stabilize the column and prevent beads from rising. Guidance from a Purolite technical expert is recommended.

Suggested regeneration parameters:

Regenerant Flow Rate: 2-6 BV/h (2 BV/h typical)
Regenerant Contact Time: 15-60 minutes (> 30 minutes preferred)
Slow Rinse: Normally same flow rate and time as the regenerant.
Fast Rinse: Same flow rate as the service flow, typically 30 minutes.