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Calcium Hydroxapatite for the removal of heavy metals and fluoride

Calcium Hydroxapatite for the removal of heavy metals and fluoride

Fluoride adsorption by calcium hydroxyapatite
Posted at 19:18 By

Calcium Hydroxyapatite for heavy metals and fluoride removal from potable and waste water.

Hydroxyapatite is a naturally occurring form of the mineral calcium apatite—calcium, phosphorous, and oxygen—that grows in hexagonal crystals. Hydroxyapatite is the main mineral of which tooth enamel and dentine are composed off, as well as bones .Calcium Hydroxyapatite has the formula Ca5(PO4)3(OH), but it is usually written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two entities. The OHion can be replaced by fluoride, chloride or carbonate, producing fluorapatite or chlorapatite.

The natural Calcium Hydroxypatite limestone based media is chemically activated in conjunction with aluminium. The media is typically supplied as a moist media with particle size of average 1 mm. Pacific Water Technology has proven this media for various commercial applications for the removal of contaminants from potable and waste water. Fluoride is removed from aqueous solutions by fluoride ions displacing the hydroxide group in the mineral . This process is reversible, therefor enabling this media to be regenerated. Heavy metals are also adsorbed by the media , therefor making it a very versatile filtration media for removal of various contaminants. The Calcium hydroxyapatite media has superior performance to other media including bone char , fluoride specific ion exchange resins and activated alumina.

Hydroxyapatite Features and Benefits

  • High capacity and shorter contact time
  • Very safe to use; no dissolution of toxic and hazardous substances
  • High efficiency, NEWDEF®1 can remove up to 99% fluoride in raw water.
  • Limited inhibition by other competing ions
  • Lower regeneration cost and simple regeneration process
  • Not only restricted to Fluoride ,but can remove iron and manganese as well
  • Can be regenerated. More:

 

Below are the results from a trial performed with the media , using a two minute contact time . The water was spiked with various contaminant levels ,exceeding what you would typically find in natural or potable water sources.

Contaminant: Percentage Reduction:

Fluoride 99%

Lead 98%

Copper 99%

Arsenic 96%

Manganese 99%

Zinc 99%

The required contact time compared to activated alumina is significantly shorter , therefor making this media much more practical and economical for water filtration applications.

 

 

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