I have googled myself to death. That is why I am here, hoping someone can help.
This is for a small (125 gpm) waste water application. The upstream water source is groundwater, treated with RO. The stream we are treating is the RO concentrate with less than 10 mg/l fluoride. There is no POTW to discharge to - there is a NPDES permit restricting the F to 3.3 mg/l.
The plan is to treat the water with AA filters, then treat the regenerant waste with CaCl2 to precipitate the CaF2. CaF2 would then be filter pressed and land filled; supernatant would be discharged via a NPDES permit.