Fluoride is found in
wastewater from glass etching operations, semiconductor manufacturing and metal
The most common method of treatment is the precipitation of calcium fluoride
using calcium from either lime or calcium chloride. This method reduces the
dissolved fluoride concentration to 10 mg/l.
lf the water is retreated with aluminum hydroxide, the fluoride can be reduced
to 5 mg/l.
Typical fluoride limits are 17 mg/l.