In contrast to chlorides and sulfates, fluorides are toxic to biota even at low concentrations (Stevens et al. 2000; Palmieri et al. 2014). Fluoride concentration was analyzed in the leachate, as it may be present in foundry waste. Organic binders are the main source of fluorides in foundry waste leachate (http://life-foundrysand.com). The fluoride concentration was low in all tested leachate. Plant resistance to fluoride depends on the plant species. Stevens et al. (1998) report the toxic for p
Letter
Since it has been established that the dental disease in man known as "mottled enamel" is due to the drinking of water containing fluorine, the removal of fluorides by filtration has become an important problem.
I have found that a contact filter 15 cm high, made of river sand passing a screen 60 to the inch, to which has been added 2 per cent. by weight of powdered aluminium, will remove the fluoride from a solution containing 30 parts per million of sodium fluoride. The absence of f
