Chemicals Based
Technologies - An Improved Method of Fluoride Treatment
in Aqueous Effluent
Introduction
For human consumption, fluoride concentration
in water should be between 0.8 ppm to 1.5 ppm. Potable
water having fluoride less than 0.8 ppm is not good
for tooth, bone etc. Again, if the fluoride concentration
is more than 1.5 ppm, it causes a disease called "fluorosis",
which is a major problem in many villages of our country.
In industrial effluents, fluoride
concentration can be as high as 5%. This industrial
fluoride effluent can be of both acidic and alkaline
nature. If this high concentration of F- ion is not
treated properly before its disposal, it may lead to
serious environmental and public health hazard. So,
the fluoride waste is generally treated by the conventional
method of lime treatment before its final disposal.
By this method, though the fluoride concentration of
the effluent can be reduced, it can not be lowered to
less than 10-15 ppm. Further, solubility of CaO specially
in alkaline medium or in plain water is poor as a result
of which the whole process becomes very slow.
Process
As per the improved patented method
developed in Bhabha Atomic Research Centre, the process
consists of Calcium (Ca+2) treatment of effluent followed
by complexing the fluoride ion and pH control. This
method has been very effective to reduce the fluoride
concentration in both acidic and alkaline effluents,
down to 1.5 ppm. The process as such is relatively faster
also. The solid waste, primarily CaF2 generated out
of this process, can either be dried and used/sold or
disposed off as solid waste depending upon the specific
industrial activity.
Equipment
The standard chemical processing equipments
such as treatment tanks with agitator, settling tanks,
pumps , filter presses, pH meter, flow meters and fluoride
specific ion meter would be required.
Infra-Structure Requirement
Power : Power requirement
is only for pumps and agitators. Man power : Main man-hours are needed to weigh
and add reagents, cleaning filter press, process and
pack by-product for selling / disposal etc.
For further information please contact
:
Head,
Technology Transfer & Collaboration Division,
Bhabha Atomic Research Centre, Trombay,
Mumbai - 400 085
Tel : 091-022-25505337/25593897
Fax : 091-022-25505151
E-mail : headttcd@barc.gov.in
