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Fluoridation - Coggle Diagram
Fluoridation
Distillation
How it works ?
3) liquid water produced from the condensed steam contains very little dissolved material
require energy to heat the water
2) steam contains very little of the dissolved matter present in the water
1) convert liquid water to steam and collect the condensed steam for use
remove fluoride up to 99% from water
effectiveness not affected by pH of water
Advantages
any failure will become very obvious as no water will come out
does not become exhausted
type of fluoride compounds used:
fluorosilicic acid
inexpensive
liquid by product of phosphate fertiliser
available in varying strengths (contains more water )
shipping = expensive
most commonly used additive for water fluoridation
hexafluorosilicic, hexafluosilicic, hydrofluosilicic, and silicofluoric acid.
sodium fluorosilicate
sodium silicofluoride
powder or very fine crystal
easier to ship
sodium fluoride
more expensive
white, odourless powder or crystal
minimise dust
first compound used and the reference standard
easy to handle
toxic in gram quantities by ingestion or inhalation
Implementation
not affect
taste
smell
appearance
Definition:
Addition of fluorides to drinking-water, aimed at lowering tooth decay rate of general population.
1 ppm of fluorine ions in water is effective in reducing dental cavities
high amount : fluorisis
Fluoride removal
defluoridation
type of filters
remove 90% of fluoride
reverse osmosis
depends on chemistry of the water and the material from which the membrane is made
can be filtered 85% to 95% of the fluoride
effectiveness of the membrane is not affected by the pH of the water
How it works ?
uses a membrane with very fine pores
to remove dissolved substances from the water
water molecules are forced through the pores under pressure
the size of dissolved molecules in the water determines how easily they will go through the pores
only a small fraction of the water passes through the pores and available at the outlet of the filter
the rest of the water with high concentration of dissolved substances goes to waste
Energy is needed to pressurise the water (air pump)
the removal not specific to a particular substances
deionizers
activated alumina
aluminium oxide
highly porous and adsorbent material
most effective: acidic pH of 5.0
85% to 95% of fluoride may be removed
does not have endless capacity to adsorb fluoride
once fitler cannoy adsorb anymore, need to be replaced
How it works ?
activated carbon filter is used after the activated alumina
to remove taste from the water
water that contais fluoride passes through it, fluoride adsorbs onto the alumina
household treatment units cannot adjust the pH of the water
this level of fluoride removal may not be reached
Objective:
to prevent tooth decay