The Treatment of Fluoride Wastes
WALTER ZABBAN, Partner
The Chester Engineers
Pittsburgh, Pennsylvania
H. W. JEWETT. Engineer
Corning Glass Works
Corning, New York
INTRODUCTION
Fluoride compounds are found in the waste discharges from those glass surface
treatment processes which utilize the reactivity of hydrofluoric acid for toe removal of minute cracks and flaws, or for the production of a frosted surface, as in
the case of light bulbs.
The glass manufacturing industry is not the only industry that discharges fluoride wastes. Typical of industries that discharge fluorides are the fertilizer, the
pesticide, the steel and aluminum industries. By far the greatest amount of fluoride, and more specifically silicon tetrafluoride, is discharged in the manufacture
of fertilizer from phosphate rock. One of toe major ingredients of that naturally
occurring phosphate compound is apatite which contains fluorine.
Although not all of toe waste effluents from the above-mentioned manufacturing operations are entirely of the aqueous type, airborne fluoride compounds
become waterborne after they have been scrubbed with water or with aqueous
alkaline reagents.
As regards toe effect of fluoride compounds on animals and on vegetation, it
is appropriate to differentiate between aqueous and airborne fluorides. Perhaps
toe strictest requirement affecting the discharge of aqueous fluorides to bodies of
water is that which is based on the 1962 Public Health Service Drinking Water
Standards. The "Standards" limit toe fluoride concentration to a range of 0.7 to
1.2 mg/1 as toe annual average of maximum daily air temperature varies between
90.5 and 50 F. The effect of fluorides in drinking water for animals should be
analogous to those for human beings. This is verified in the literature survey published in Water Quality Criteria (1).
The literature data (2,3,4,5) on the effects of fluorides on fish life appear to
confirm the fact that the toxic limits for eggs, fingerlings and adult fish are
greater than the limits set by toe Public Health Service Drinking Water Standards
(1962).
As regards toe effects of aqueous inorganic fluorides on vegetation, a concentration of 10 mg/1 of fluoride is not known to have caused injury to peach,
tomato and buckwheat plants; however, a concentration of 100 mg/1 has severely
injured peach and buckwheat plants in three days (1). Even though toe data on
toe effect of aqueous fluorides on irrigated vegetation are not as reliable as on the
effects of airborne fluorides, it appears that toe toxic limits are well above those
stipulated by the Public Health Service Drinking Water Standards.
A description of toe effects of inorganic fluorides on animals has been furnished by J. W. Suttie (6), based on damage to animals which graze on vegetation
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