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Water Fluoridation


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    Dr shabeelpn
  • 2.
    • Dean and co-workers in USA
    • 3. Decreased F- caries; Increased F-Dental fluorosis
    • 4. Normal F content- 1-1.5mg of fluoride/litre
  • 5. Defined as the upward adjustment of the concentration of fluoride ion in a public health water supply such a way that concentration of fluoride ion in water may be consistently maintained at one part per million by weight to prevent dental caries with minimum possibility of causing dental fluorosis.
  • 6.
    • In temperate regions – 1ppm.
    Optimal fluoride concentration & climatic conditions.
  • 7.
    • For colder climates where the mean annual maximum air temperature is lower than 10 degree celcius fluoride concentration in water as high as 1.3 ppm must be considered safe and beneficial
    • Irrigation water – 10 mg/l
    • 8. Aquatic life - 1.5 mg/l
    • 9. Industrial water supply – 1.0 mg/l
    Levels of fluoride used.
  • 10. Before fluoridation , the following factors should be taken into account
    Daily fluoride concentration of the water supply
    Baseline dental caries prevalence
    Index of enamel fluorosis and post fluoridation data of the same population.
  • 11. Japanese limit their fluoride content since they eat fish which is rich in fluorides.
  • 12.
    • 500 ml of water is taken in a clean dry polythene container
    • 13. 2cc of 6 N HCl is added to inhibit growth/enzymatic change
    • 14. Store at 4 degree celsius for analysis.
    Sample collection for fluoride estimation.
  • 15. Fluoride concentration can be estimated by
    Fluoride electrode coupled with standard pH meter.
    Scot- Sanchis method
  • 16. Universally acceptable, quick, simple, economic.
    pH meter is used in conjuction with a fluoride electrode & electrode potentials of the sample is calculated.
    Two pH meters are used-Orion901 & Orion 407
    Ion meter is one that has inbuilt facility of converting the electrode potentials into concentration of fluoride in ppm
    Fluoride electrode coupled with standard pH meter
  • 17. The unknown concentration of fluoride is calculated by
    Typical calibration curve
    Applying electrode potential difference by equation
    Direct ppm reading.
  • 18. Scot – Sanchis method
    • Based on reaction between fluoride and red zirconium alizarine lake.
    • 19. Fluoride forms a colourless complex ion-ZrF6 & liberates free alizarinesulphuric acid(yellow)
    • 20. As the amount of fluoride increases, the colour varies from yellow to red.
    • 21. Fluoride level is determined by comparing the colour with that of standards.
    • 22. No longer used.
  • 50 percent of population in rural areas.
    Centralised water distribution system is lacking.
    Limitations of community water fluoridation.
  • 23.
    • Should be adapted to local conditions & needs of water network
    • 24. Must be efficacious, safe &precise in all climatic conditions
    • 25. Of standard type-maintenance easily provided.
    • 26. Choice of distributor should be based on the quantity & type of fluoride bearing product used
    • 27. Equipment should have well defined precision limits i.e not more than 5 percent error in the
    Choice of equipment & chemical for water fluoridation.
  • 28. Whole system whatever variation in quantity of water
    It should have a safety mechanism that automatically stops the addition of fluoride if the flow through the treatment plant is suddenly reduced
    Adjustment must be easy and rapid
    Apparatus should operate between 20 & 80 percent of total capacity
  • 29. In each fluoridation system, an antisiphon mechanism should be installed in pipes distribute fluoride solution into water, to avoid a concentrated solution of fluoride entering the system.
  • 30. Fluorspar-
    mineral containing varying amounts of CaF2
    b) Sodium fluoride-
    white, odorless,free flowing material available either as a powder or a mixture of various crystals
    - expensive source of fluorides
    c) Silicofluoride-
    obtained as by product of purification of phosphate rocks
    Fluoride compounds used in water fluoridation
  • 31. d)Sodium silicofluoride
    - Most popular
    - Low cost, cheapest form of fluoride
    - Solutions are corrosive.
    e)Hydrofluosilic acid
    - More expensive
    f)Ammonium silicofluoride
    - Produced by neutralisingfluosilic acid with either aqueous ammonia or ammonia in gaseos form
  • 32. The saturator system
    The dry feeder system
    The solution feeder system
    Types of equipment for water fluoridation
  • 33. Principle – 4 percent solution of sodium fluoride is produced and injected at the desired concentration at the water distribution source with the aid of a pump.
    The saturator system
  • 34. Factors limiting the utilisation –
    a high hard water level ( total hardness of over 75 mg/l)
    Recommendation –
    for small town with a total requirement of less than 3.8 million litres/ day
  • 35. Principle – Sodium fluoride or silicofluoride in the form of powder is introduced into a dissolving basin with the aid of an automatic mechanism
    The dry feeder
  • 36. Factor limiting utilisation –
    the need for care of handling of fluoride, obstruction of pipes, compacting of fluoride while stacked in humid atmosphere.
    Recommendation –
    in medium sized town- 3.8 -19 million l/day
  • 37. Principle- Volumetric pump permitting the addition of a given quantity of hydrofluosilic acid in proportion to amounts of water treated.
    The solution feeder
  • 38. Factors limiting utilisation –
    resistant to attack by hydrofluosilic acid
    Recommendation –
    in medium and large towns
    Capacity more than 7.6 million/ day
  • 39. These three systems incorporate electrical and mechanical devices that require maintenance by capable operators.
    The Venturifluoridatorsystem and the saturation suspension cone are the two systems which do not suffer from these drawbacks.
  • 40.
    • Non electrical system developed by J N Leo
    • 41. Activated by the flow of water in the main water line and there no possibility of accidental overdosing by surges of fluoride when the main water pump stops
    • 42. The tank containing fluoride is made of clear acrylic thermoplastic(plexiglass)
    Venturifluoridator system
  • 43. Simple to install
    Cost is only three-fourths even though same amount of chemicals are used
    Non electrical system
    Operator can make visual inspection of the level of chemicals
  • 44. Consists of an upside down cone charged with a bag of sodium silicofluoride through which a constant flow of water percolates
    The solution is collected at the top by a horizontal perforated plastic pipe which forms the outlet
    Saturation suspension cone
  • 45. A cone 0.91m high and 0.91m in diameter, mounted upside down
    An elevated constant head tank(7-10m head) for feeding water to prepare a constant volume of solution
    A 2cm diameter connecting pipe from the constant head tank to the lower end of the cone
    A surface collector consisting of a horizontal perforated 2.5 cm diameter pipe collects the solution and discharges into a wide mouth funnel which is connected to the pipe
    Parts of installation
  • 46. The cone must be built of a corrosion resistant material such as stainless steel or fibreglass
    The cone is charged with a 45 kg bag of sodium silicofluoride
    The quantity of salt in the cone be never less than 25 kg
  • 47. Maintenance and control
    • The fluoridation system must be carefully maintained to ensure maximum efficiency
    • 48. Uniform concentration of fluoride ions should be maintained
    Technical considerations of water fluoridation
  • 49. Control at the water treatment plans
    • Any difference in the fluoride content of water should be checked
    • 50. The analysis should be done several times a day
  • Control of the quality of analysis
    • The responding authority should send three blind samples each month for analysis at the water treatment plant which should be returned to the responsible authority within 48 hrs
    • 51. If any difference known, technical assistance should be sought
  • d) Control of the quality of water in the network
    • Personnel from the water plant should take samples from the network once a week and send them for analysis
    • 52. Fluctuations in concentrations should be noted
  • e) Control of the quality of fluorides used
    • Each time the delivery of fluorides is received, the samples should be analysed to verify whether they correspond to the criteria of quality approved by the responsible authorities.
  • a) Hourly check of he weight of the chemical fed into the hopper.
    b) Calorimetric chemical testing through addition of zirconium alizarin reagent and the results to be compared with the standards
    c) Less frequent calorimetric testing is advisable(at weekly intervals) upon water at various parts of the distribution system
    d) Continuous electronic measuring and controlling of fluoride concentration in water
    Monitoring of fluoridated water
  • 53.
    • To reduce the fluoride concentration to optimal level
    • 54. Reduce occurrence of dental fluorosis.
    • 55. Avoid other adverse effects.
    Partial removal of fluoride
  • 56. At a central water treatment plant by absorption of fluoride in a suitable medium by means of an ion exchange process
    By the use of smaller units using similar principles, installed at home and other places where drinking water is made available for children
    By bringing of water of lower fluoride content from other sources to mix with and dilute the high fluoride water.
    Achieved by
  • 57. 4) By providing bottled lower fluoride water separately to homes and other places where children drink water
  • 58.
    • There is municipal water supply reaching a reasonable number of homes
    • 59. People drink this water rather than water from individual wells or tanks
    • 60. Suitable equipment is available in a treatment plant or pumping station
    • 61. A supply of a suitable fluoride chemical is assured
    • 62. There are workers in the water treatment plant able to maintain the system
    Practical aspects of water fluoridation
  • 63.
    • There is sufficient money available for the initial installation and running costs
    But with increase in dental caries, it is urged that water fluoridation be considered soon as safe drinking water
  • 64. Medical investigations shown that optimal concentration of fluoride is safe and does not impair general health
    In cases of excessive fluoride intake either in areas of high concentration or in industrially polluted drinking water , secondary effects might appear in the form of dental and skeletal fluorosis.
    Evaluation and safety of water fluoridation
  • 65. Attained by the country of a fair level of economic development.
    Availability of municipal water supplies reaching a large number of homes.
    Evidence that people drink water from the municipal supply rather than from wells or tanks.
    Availability of the requisite equipment needed in a treatment plant.
    Availability of reliable supply of fluoride
    Requirements for introducing community water fluoridation
  • 66. Availability of trained workers who are able to maintain the system.
    Availability of sufficient money.
    A level of dental caries in the community that is high or firm indicating that caries level is increasing.
    Appropriate legisation authorizing community water fluoridation
  • 67. Several methods have been suggested
    Based upon ion exchange process or adsorption and
    Based upon addition of chemicals to water during treatment.
    In India, the first work on defluoridation was done by the National Environmental Engineering Research Institute (NEERI) at Nagpur in 1961.
    Defluoridation of water
  • 68. Defluoron 1 : A sulphonated raw dust impregnated with 2 percntalim solution.
    Carbion: Used on sodium and hydrogen cycles
    Magnesia: It removed the excess fluoride but pH of treated water was beyond 10 and its correction by acidification and recarbonation was necessary.
    Defluoron 2 : It is a sulphonated coal and works on aluminium cycles
    Cation Exchange Resins
  • 69. Involves addition of two readily available chemicals
    Addition of sodium aluminate or lime, bleaching powder and filter alum to the fluoride water followed by flocculation, sedimentation and filtration.
    Useful for domestic and community water supplies.
    Nalgonda technique of defluoridation
  • 70.
    • These are stainless steel candle filters adopting Nalgonda technique
    • 71. Consists of water filters of any size and make fitted with candle filters and an additional mixing device
    Domestic defluoridation filters
  • 72. Rapid mix: Is an operation by which the coagulant is rapidly and uniformly dispersed throughout single or multiple phase system
    Helps in formation of microflocs and results in proper utilization of chemical coagulant, preventing localisation of concentration and premature formation of hydroxides.
    Mechanism of defluoridation by Nalgonda technique
  • 73. Flocculation:
    Second stage of the formation of settable particles(flocs) from destabilised colloidal sized particles and is achieved by gentle and prolonged mixing.
    • Sedimentation:
    Separation from the water by gravitational setting of suspended particles that are heavier than water
  • 74. Factors influencing sedimentation
    Size, shape,density and nature of the particles
    Viscosity, density and temperature of water
    Surface overflow rate
    Velocity of flow
    Effective depth of setting zone
  • 75. Filtration
    It is a process for separating suspended and colloidal impurities from water by passage through porous media.
  • 76. Fill 22 litres of test water in the upper chamber
    Add the required dose of aluminium salt solution
    Mix it rapidly for a period for 30-60 seconds with a speed of 10 – 20 rpm
    On chemical reaction tiny flocs are formed
    Then mix for a period of 10-15 min with a speed of 2-4 rpm
    Water is allowed to settle and filter through
    Operation and maintenance of Nalgonda technique
  • 77. earth candles overnight
    Salient features of Nalgonda technique
    • No regeneration of media
    • 78. No handling of caustic acids and alkalies
    • 79. Readily available chemicals used in conventional municipal water treatment are only required
    • 80. Adaptable to domestic use
    • 81. Simplicity of design, construction, operation and maintenance
    • Highly efficient removal of fluoride
    • 82. Little wastage of water
    • 83. Minimum mehanical and electrical equipment
    • 84. No energy except muscle power required
  • Absence of acceptable,alternate low fluoride source within transportable distance
    Total dissolved solids are below 1500mg/l; desalination may be necessary
    Raw water fluoride ranging from 1.5mg to 20 mg F/l
  • 85. THANK YOU