Abstract:
Water sources in specific regions of dry zone in Sri Lanka naturally contain high fluoride
level than the maximum requirement level of drinking water. The intake of excessive
amounts of fluoride in water causes different human health issues. This study was
intended to identify the potential of using the biomaterials for an integrated water
filtration system to improve the water quality. Based on the literature records, production
cost and availability of biomaterials, Areca nut (Areca catechu) husk fiber, Coconut
(Cocos nucifera) spathe charcoal and Snake Cucumber (Cucumis melo) seeds were used
to identify the fluoride removal rate in water. Fluoride rich natural water was subjected to
different biomaterial weight and treatment time combinations during preliminary trials.
Based on the results of preliminary trials, the final experiment was conducted in the
column systems using four types of integrated water filter setups at different weight ratios
between areca nut husk fiber: coconut spathe charcoal {Experimental setups: A (1:1,
25g:25g), B (1:2, 25g:50g), C (1:1, 50g:50g), D (2:1, 50g:25g)} with 3 layers of sand.
Equal treatment period (1½ hrs) was used for all 4 column experimental setups since the
adsorption capacity of biomaterials depends on the contact time. Fluoride removal
efficiency and other water quality parameters were measured in each filter setup.
Biomaterials amount in the filter setups had a significant effect on the fluoride level, pH,
and Total Dissolved Solids in water (p<0.05). The fluoride removal rate of filter setups
was 27.90%, 28.80%, 34.49%, and 43.15% in the A, B, C, and D systems respectively.
Although the same biomaterial ratio (1:1) had for the A and C experimental setups, the
fluoride removal efficiency was significantly different due to the variations of
biomaterials dose in two systems (A: 25g, C: 50g). The most effective filter setup was
identified as the integrated system with 50g of areca nut husk fiber and 25g of coconut
spathe charcoal considering Sri Lanka Standards for potable water (SLS 614:2013).
Turbidity, nitrate, nitrite, phosphate, sulphate, iron, and chloride level of water had
recorded the acceptable levels as meeting with drinking water standards after 1½ hrs of
the treatment period. The pH of all the filter setup was recorded at the range of 7.1-8.1
within the permissible level for drinking water. In conclusion, areca nut husk fiber and
coconut spathe charcoal act as effective, low-cost biomaterials in removing the fluoride
from water while maintaining the quality of water.
Keywords: Water quality, Biomaterials, Integrated water filter system, Fluoride removal
rate, Fluorosis
