Environmental Engineering Reference
In-Depth Information
luoride, and aluminum parameters were also studied for deluoridation of water. The
maximum luoride removal eficiency of adsorbent was optimized. The study recom-
mended that aluminum oxalate can be used as a potential deluoridating agent in soil pots
as a green chemical approach without much environmental impacts.
17.7.8.5.1 Domestic Deluoridation Method by IISc (Indian Institute of Science)
Bangalore, India (adopted from http://civil.iisc.ernet.in/~msrao/
iles/applicationIIScmethod.pdf, with permission from IISc)
The IISc's method relies on a magnesium oxide-based precipitation-sedimentation-
iltration technique to reduce luoride concentrations in water to permissible levels (<1.5
ppm). It uses a domestic deluoridation unit (DDU) to implement the chemical treatment
procedure. The magnesium oxide method for luoride removal is reported to have several
advantages. Magnesium oxide has limited solubility in water and therefore does not add
to the TDS. All chemicals used in the process are nontoxic. The alkaline pH of the mag-
nesium oxide-treated water is easily neutralized by addition of sodium bisulfate solution.
The method does not involve any recharge process and thus avoids generation of corro-
sive and toxic wastes. The method is designed to treat luoride-contaminated groundwater
with varied ionic composition. Technology for reuse of sludge into stabilized mud blocks
has also been developed.
A simple-to-use 15- and 100-L DDU treats luoride-contaminated water using the IISc
method. The 100-L DDU is composed of a 100-L-capacity polyvinyl chloride
(PVC) drum
and is equipped with a heavy-duty electrical stirrer. The 15-L DDU is composed of a
20-25-L-capacity SS drum and is equipped with a light-duty electrical stirrer or a hand-
operated mechanical stirrer. The units serve as a mixing-cum-sedimentation unit. Taps
are ixed above the base of the containers to drain the treated water. To trap any escaping
sludge particles from the unit, a cotton cloth ilter is tied to the tap of the upper unit. The
cost of treating 1 L of luoride-contaminated water by the IISc method is 17-27 paise/L
(~0.4 cents) (Figure 17.10).
FIGURE 17.10
Field implementation of IISc method in Shola village, Laxmangarh district, Rajasthan, by Dr. Kushal Quango,
Modi Institute of Technology, Rajasthan. (Copyright permission from IISC.)
