I am looking to remove an heavy metal by ion exchange column. The concentration of heavy metal in the water is only 25 ppb. I had already got the equilibrium isotherm capacity at 25 ppb. Assuming the operating capacity as 50% isotherm capacity, at a specific flow rate of 10 BV/hr, the column exhaustion time is 150 days.
Is there any way where I can reduce the experiment running time ?. I have to maintain the same specific flow rate as it can be used for scale up.
Dear Ms. Rajalakshmi,
this a very good question. We had the same problem when designing lab column trials using our iron-based adsorbent material GEH (Granular Ferric Hydroxide) for arsenic removal from drinking water. When considering the same specific throughput (e.g. 10 BV/hour), the duration of the lab test is the same as of the planned full-scale plant.
We used successfully the method "Rapid Small Column Test RSSCT" to accelarate the testing. This method was originally developed for Granular Activated Carbon filters by Crittenden et al (1991).
Reference: Article Predicting GAC Performance with Rapid Small-Scale Test Columns
The method was applied by Westerhoff et al for iron-based adsorbents
Article Rapid Small-Scale Column Tests for Arsenate Removal in Iron ...
The idea of this method is to use a smaller particle size of the adsorbent, which enables a higher filter velocity / shorter Empty Bed Contact Time (i.e. higher specific throughput). Dependig on design of the RSSCT, you can significantly shorten the testing time.
But I am not sure, if the RSSCT method is already successfully applied for Ion Exchange Resins (as used in your project). When using GAC or GEH adsorbents, it is very easy to have a smaller grain size (by grinding and sieving the material). But this is probably not possible for IEX resins. Perhaps the IEX supplier could provide you with a finer fraction of the IEX resin?
Best regards
Carsten
Thanks Carsten for your elaborate answer. Grinding the resin would cause the loss of functional groups / Ion exchange capacity. I checked with my resin supplier, there is no method established for speeding up of break thru experiment.
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