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[fseipel]

I have experience with distillation, but not much with stripping.  I'm trying to assess performance of an existing air stripper meant to remove BTEX from a wastewater stream using air.  Countercurrent, with random packing.

 

It currently has a RECYCLE that takes water from the column bottom sump, where it joins with fresh contaminated wastewater, and is then sprayed on the packing.  Before the fresh feed joins into this stream, is the product water take-off.  My questions are: Is it better to not recycle at all across packing, to keep concentration gradient the highest?  And secondly, how is the air-to-liquid ratio calculated when you have recycle?  The articles I've read on this topic don't seem to address recycle or have recycle, hence this question.  Recycle flow rate is several times feed flow rate.