Q.8. What is fluoride problem in drinking
water? (AKTU. - 2009 - 10)
Related Questions -
Q. Write explanatory note on fluoride
problem in drinking water. (AKTU. - 2008 - 09)
Q. Discuss the fluoride problem in
India. Discuss its effect on human health. (AKTU. - 2010 - 11)
Q. Write an essay on fluoride problem
in drinking water. (AKTU. - 2012 - 13)
Ans. Fluoride Problem In Drinking Water: -
Under normal use of water resources, the
fluoride problem would not have become such a widespread issue. Fluoride
contamination began only when we went deeper and deeper into the ground to
extract increasing amounts of water.
Excess intake of fluoride leads
to fluorosis; dental, skeletal, or non-skeletal. Dental fluorosis results in
blackened, mottled, or cracked teeth. Skeletal fluorosis means permanent and
severe bone and joint deformities. Non-skeletal fluorosis leads to
gastro-intestinal and neurological problems.
High fluoride concentration in
groundwater occurs naturally in a number of countries. While fluorosis is most
severe and widespread in India and China, it is endemic in at least 25
countries across the globe. The Indian geology is such that the bedrock
contains mineral with high fluoride content. When the bedrock weathers, the
fluoride leaches into the water and soil.
In India, fluorosis has wiped
out the economy of whole villages by disabling most of the inhabitants. To
women, the disease brings social stigma. Normally, the disease does not lead to
death, but to extreme suffering. As someone put it, ‘It neither allows a person
to live nor to die.’
Q.9. Discuss the importance of flouride in
drinking water. (AKTU. - 2009 - 10)
Ans. Fluoride is one of the important elements which is essential for
man as well as for animals. Most adults take fluoride between 1.0 to 3.0 mg
daily. The main source is usually drinking water which is contain 1.0 ppm of
fluoride, will supply 1.0 - 2.0 mg/day. Soft waters usually contain no
fluoride, while very hard waters may contain over 10.0 ppm. The regular
presence of fluoride in minute amounts in human bones and teeth and its
influence on the prevention of dental carries justifies its inclusion as an
element of importance in human nutrition.
Fluoride is a double edged
sword. On one side, it is an essential element in human nutrition as it
prevents dental carries, on the other hand, if its intake is excessive, its is
toxic and cause dental and skeletal fluorosis.
Q.10. What is dam. Discuss the benefits and problems
of dam. (AKTU. - 2005 - 06)
Ans. Dam
is the structure of concrete constructed to retain water which creates ponds,
Lakes. It acts like a barrier across the river. This water now can be utilized
for various purposes. But is creates some problems.
Benefits
of dam:
1. The water stored can be used for
generation of electricity.
2. Water can be used in drought-prone areas.
3. Water can also be utilized for irrigation
purpose.
4. Dam construction provides employment to
many people.
5. It promotes navigation and fishery.
Problems
due to dam:
1. Deforestation is followed for the
construction of dam.
2. Destruction of life.
3. Tribal people lose their habitat.
4. Chances of earthquake.
5. Increase humidity over a large area causes
deterioration of the monuments.
Q.11. Briefly discuss
‘Nalgonda Technique’ of defluoridation of water to control the problem of
fluorosis. (AKTU. - 2009 - 10)
Ans. Nalgonda Technique: -
Defluoridation
is removal of excess fluorides from water. Removal is achievable either by
precipitation and complexation process (Nalgonda Technique) or by fixed bed
generatable Activated Alumina process. The recommended defluoridation method is
Nalgonda Technique.
Mechanism Of Defluoridation By Nalgonda Technique: -
Nalgonda
Technique is combination of several unit operations and process incorporating
rapid mixing, chemical interaction, flocculation, sedimentation, filtration,
disinfection and sludge concentration to recover water and aluminum salt .
Rapid Mix: -
Provides
thorough mixing of alkali, aluminium salts and bleaching powder with the water.
The chemicals are added just when the water enters the system.
Flocculation: -
Flocculators
provide subsequent gentle agitation before entry to the sedimentation tank. The
flocculation period permits close contact between the fluoride in water and
polyalumenic species formed in the system. The interaction between fluoride and
aluminium species attains equilibrium.
The chemical
reaction involving fluorides and aluminium species is complex. It is a
combination of polyhydroxy aluminium species complexation with fluorides and
their adsorption on polymeric aluminium hydroxides (floc).
Sedimentation: -
Permits
settleable floc loaded with fuorides, turbidity, bacteria, and other impurities
to be deposited and thus reduces concentration of suspended solids that must be
removed by filters. Sedimentation theory is complex and of little avail,
because floc is not uniform and hence its basic sedimentation properties cannot
be given quantitative values and because the influence of eddy currents cannot
be predicated. Hence, various factors which influence sedimentation in relation
to design and operation rely largely on experience
Filtration: -
Rapid gravity
sand filters are suggested to receive caugulated and settled water. In these
filters unsettled gelatinous floc is retained. Residual fluorides and bacteria
are absorbed on the gelatinous floc retained on the filter bed.
Disinfection and Distribution: -
The filtered water collected in the
storage water tank is rechlorinated with bleaching powder before distribution.
