Household Water Treatment and Safe Storage Factsheet: Source ...

Household Water Treatment for Fluoride Removal
Factsheet: Activated Alumina Filter
Activated alumina filters can also consist of a
domestic candle water filter with an additional
middle chamber holding a bag of activated
alumina. The filter could also simply be an
bucket, drum or column with a tap and
drainage pipe that is filled with activated
alumina (see illustration below).
The contact time of the filter is the amount of
time the fluoride contaminated water is in
contact with the activated alumina. Bulusu and
Nawlakhe (1988) conducted jar test
experiments to determine the effect of contact
time on fluoride removal. It was observed that
the optimum contact time to reduce the fluoride
level from 4.8 mg/L to 1 mg/L is 30 minutes.
This can be used as a recommendation, but as
of yet there is no formal recommendation for
contact time.
When the activated alumina media becomes
saturated, meaning there are no more places
for fluoride to adsorb to the media, the media
can be regenerated using HCl, H 2 SO 4 , alum or
NaOH. The wastewater created from this
process should be disposed of in an
appropriate manner away from water sources
and human contact.
Note: When 4% caustic soda (NaOH) is used
for regeneration it needs to be followed by a
neutralization step to remove residual NaOH
from the filter.
Three Common Household Units for Sorption Defluoridation
(Credit: WHO, 2006)