Which material is used for removing fluorides from hard water containing 3ppm of fluorides?
(a) Lime
(b) Copper sulfate
(c) Synthetic tri-calcium phosphate
(d) Bone charcoal
I had been asked this question by my school principal while I was bunking the class.
This interesting question is from Fluoridation and Defluoridation topic in section Miscellaneous Treatment Methods of Environmental Engineering