Water Fluridation & Defluridation

T R E A T M E N T O F W A T E R |

F LU O R I D AT I O N &

D E F LU O R I D AT IO N

B U I L D I N G S E R V I C E S W A T E R S U P P L Y A N D S A N I T A T I O N

F L U O R I N E• Fluorine is the 13th most

abundant naturally occurring element in the Earth’s crust and is the lightest member of the halogens. It is the most electronegative and reactive of all the elements and as a result, elemental fluorine does not occur in nature but found as a fluoride mineral complexes.

B U I L D I N G S E R V I C E S - W A T E R S U P P L Y A N D S A N I T A T I O N

W AT E R• Water is frequently

referred to as a universal solvent, because it has the ability to dissolve almost all substance; that comes in its contact. Some elements are essential in trace amount for human being while higher concentration of the same can cause toxic effects. Fluoride is one of them.


C O N C E R N F O R W A T E R T R E A T M E N T• Due to rapid urbanization and growth of modern industries

(anthropogenic source of fluoride) as well as geo chemical dissolution of fluoride bearing minerals (natural source of fluoride), fluoride concentration is increasing in the environment including water resources. The high concentration in the drinking water leads to destruction of enamel of teeth and causes a number of conditions referred to collectively as fluorosis.


H E A L T H I M P A C T SV A R I O U S H E A L T H I M P A C T S O F F L U O R I D E

• Fluoride inhibits enzymes that breed acid-producing oral bacteria whose acid eats away tooth enamel.

• Fluoride ions bind with calcium ions, strengthening tooth enamel as it forms in children.

• Dental fl uorosis


F L U O R I D AT I O N• Water fluoridation is the process of

adding fluoride to the water supply so the level reaches approximately 0.7 ppm, or 0.7 milligrams of fluoride per liter of water; this is the optimal level for preventing tooth decay

• Fluoridation is a safe, effective, and economical process endorsed by the American Dental Association, the American Water Works Association, and public health groups worldwide.


W H AT I S W AT E R F L U O R I D AT I O N ?

• Small amounts of fluoride are present naturally in all water sources. • Water fluoridation is the precise adjustment of the

natural fluoride concentration in a public water supply up to the level recommended for preventing tooth decay.

• The common compounds which are added to water are NaF (Sodium Fluoride), Na2SiF6 (Sodium Silica Fluoride) e.t.c


• Fluoridation does not affect the

appearance, taste, or smell of drinking

water. It is normally accomplished by

adding one of three compounds to the

water.

D E F L U O R I D AT I O N• The process of water treatment that reduce the

concentration of fluoride in the water, in order to make it safe for human consumption is DEFLUORIDATION.

• Some water treatments that have the capacity of reducing the fluoride concentration along with most other anions, or anions and cations, in the water, are not considered as Defluoridation methods. Thus general demineralising methods like distillation, reverse osmosis and electro dialysis which are able to remove fluoride fully or partly from the water, are not considered as Defluoridation methods.


• On the other hand methods that only remove fluoride without any addition or reduction of other parameters are not yet discovered. That's why the expression “fluoride removal” lacks precision.

• Defluoridation is used to characterise methods that reduce the fluoride ion specifically, without major other changes to the quality of the treated water.


B A S I C R E Q U I R E M E N T S

Defluoridation devices should meet a number of the following requirements:

• Modest investment• Low maintenance cost• Simple design• Operable by villagers• Able to reduce fluoride content, e.g.

from 5 to 0.5 mg/L• Improve water quality in general


M E T H O D S O F D E F LU O R I DAT I O N• The activated carbons prepared from

various materials can be used as Defluoridation agents.

• During lime-soda process of water softening, the fluorides are also removed along with the removal of magnesium.

• The materials such as Calcium Phosphate, Bone charcoal, synthetic tricalcium phosphate, etc. may be added for the removal of excess fluoride content in water.

• The water may be allowed to pass through fi lter beds containing fluoride retaining materials.


C H A L L E N G E SMost of the above methods of

Defluoridation suffer from one or other disadvantages such as:

• High Initial Cost• Expensive regeneration• Poor Fluoride removal capacity• Hard to maintain


M O D E R N T E C H N I Q U E S

• THE NALGONDA TECHNIQUE (named after the village in India where the method was pioneered) employs flocculation principle. Nalgonda technique is a combination of several unit operations and the process involves rapid mixing, chemical interaction, flocculation, sedimentation, fi ltration, disinfection and sludge concentration to recover waters and aluminium salts.


A C T I V A T E D A L U M I N A

• Activated Alumina (Al2O3) has been activated to become adsorptive. The method of activation is done through dehydration of aluminium hydroxides at temperatures of 300-600oC


• Acti vated alumina is used in an adsorpti on process with very high fl uoride removal effi ciency. Though it has been used successfully to treat water for a number of contaminants, it has the advantage of having a very high selecti vity for fl uoride.


B O N E C H A R• Bone char is the oldest known

technology for water Defluoridation, being successfully used since the 1940s.

• Bone char has also been used successfully in the removal of arsenic from water.


• Bone char is produced with animal bones that have passed through calcination process. Though raw bones have some Defluoridation value, it is small and limited by the various organics obstructing the interfaces where chemical reactions with the fluoride take place.


• In order to produce bone char, animal bones must fi rst be collected. These bones can be collected from a variety of sources including butchers, restaurants, ranchers, etc. This can create an entirely new market by giving value to what was previously viewed primarily as a waste material.

• Once the bones are collected, they are often washed, rinsed, boiled, or sun dried to remove much of the organics before they are actually charred to be used as fi lter media.


C O N C L U S I O N• Fluoride in drinking water can cause beneficial or

detrimental effects depending on it concentration and the total amount ingested.

• The Defluoridating materials being used at present are relatively costlier. The investigations of feasible low materials for fluoride removal are needed.

• Preliminary investigations provided an encouragement to use the animal bone powder for further detailed investigations. Animal bone powder is comparatively cheap material available in abundant in nearby areas.


B I B L I O G R A P H Y

• Water Supply & Sanitary Engineering – G.S. Birdie, J.S. Birdie

• Water Supply & Sanitary Engineering – Rangwala.• www.de-fluoride.net/defluoridation.html• www.appropedia.org/Water_defluoridation

• http://en.wikipedia.org/wiki/Water_fluoridation


T H A N K Y O U


ANSIF K HABIBROLL 5SEMESTER 3

Water Fluridation & Defluridation

Education

Transcript of Water Fluridation & Defluridation