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Column model

I would be very grateful for a response to the following problem:
I am modelling  F- removal with calcite in a column packed with granular calcite (12 moles or ~1.2kg). The influent concentration of F- is 2300 mg/L (as NaF) using ADVECTION with 40 cells & 600 shifts (15 pore volumes).
On analysis of the results I find that the entire amount of calcite is used up within 6 pore volumes!!! and therefore 455.4 GRAMS of fluoride are precipitated which would require about 200 litres of my solution.
I believe this is a due to the fact that the area of the column is not specified (or controlled) and therefore the actual volume (and hence F mass) passing through the column is much greater than it should be.
Is there a way of limiting the volume of the influent solution passing through the column or programming PHREEQ so that the surface area can be taken into account??
I am using PHREEQC Interactive Alpha version 2.4.2
Brett Turner.

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